[DESCRIPTION]

[invention Title]

CONTINUOUSLY VARIABLE TRANSMISSION

[Technical Field] The present invention relates, in general, to continuously variable transmissions and, more particularly, to a continuously variable transmission which can function as a clutch to control speed and has an integrated structure, so that it can be used in various fields, for example, in a machining device, a vehicle, etc.

[Background Art]

Generally, in apparatuses using power, for example, in vehicles, machining devices, etc., power transmitted from a power source is changed in speed and torque by a transmission before it is output, rather than having the power be directly used.

Hitherto, as mechanical continuously variable transmissions having the above-mentioned functions, belt or chain mechanical continuously variable transmissions have been mainly used.

However, the belt or chain type mechanical continuously variable transmissions have the problems

below.

In the case of the belt transmission, if the belt tension is relatively low, a slipping phenomenon is probable. If the tension of the belt is excessive, overload is induced, and contact surfaces between pulleys and the belt become worn. Furthermore, a foreign substance may be undesirably interposed between the pulley and the belt, with the result that power loss is caused by slip therebetween. In the case of the chain transmission, because connection between a chain and pulleys is discontinuous, impulsive sound attributable to contact between the chain and the pulleys is induced. In addition, due to the weight of the chain, centrifugal force is increased when the chain rotates. Thus, there is a limit when it comes to increasing the speed or the size thereof.

Meanwhile, as mechanical continuously variable transmissions, there is also a method involving changing speed using a rotating conical plate and a ring which are in contact with each other, in addition to a method involving changing speed using the viscosity of oil between disks. However, in these cases, an apparatus is overly enlarged and a separate body is required, so that the installation space thereof is also increased. As well, the efficiency of power transmission is relatively low.

[Disclosure] [Technical Problem]

Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a continuously variable transmission in which elements for restraining or controlling speed to be transmitted have an integrated structure, thus reducing the volume and weight of the transmission and preventing a drive unit from being damaged by overload.

Another object of the present invention is to provide a continuously variable transmission which has a reduced installation space in an electric motor, thus reducing the entire size of the electric motor, and enhancing the efficiency of power transmission.

A further object of the present invention is to provide a continuously variable transmission which further includes a speed control unit for controlling speed, so that depending on manipulation of the speed control unit, it can be used for controlling speed of a device of large capacity, and output which is precisely changed in relation to the speed can be obtained.

[Technical Solution]

In order to accomplish the above objects, the

present invention provides a continuously variable transmission, including a housing, a gearshift control unit, a speed change unit, an input unit and an output unit. The speed change unit includes: first and second outer raceways; first and second inner raceways; and rotary members in contact with the first and second outer raceways and the first and second inner raceways. The rotary members change the speed depending on adjustment of distances between the first and second outer raceways and between the first and second inner raceways.

Here, each of the rotary members may include a rod- shaped rotary member body having a conical contact surface on each of opposite ends thereof.

Furthermore, each of the rotary members may include: a rod-shaped rotary member body having a space in a medial portion thereof; a central shaft provided in the space of the rotary member body; and a roller provided around the central shaft. A conical contact surface may be formed on each of opposite ends of the rotary member body.

In addition, each of the rotary members may have a spherical ball shape.

The rotary member may have a concave shape. As well, surfaces of the first and second outer raceways and the first and second inner raceways which are in contact with the rotary members may be convex to

correspond to the concave shapes of the rotary members .

The contact surfaces of the rotary members may be convex .

The first and second outer raceways and the first and second inner raceways may have concave surfaces corresponding to the contact surfaces of the rotary members .

The gearshift control unit may include: a cylindrical body coupled to the input unit; the first and second outer raceways coupled to the cylindrical body so as to be rotatable along with the cylindrical body, the first and second outer raceways being provided on a circumferential inner surface of the input unit, each of the first and second outer raceways having an annular shape; the first and second inner raceways having outer diameters less than inner diameters of the first and second outer raceways, the first and second inner raceways being provided around an outer surface of the output unit, wherein the first and second inner raceways are threaded to each other, and each of the first and second inner raceways has an annular shape; the rotary members provided between the first and second outer raceways and the first and second inner raceways, wherein the rotary members are in contact with the first and second outer raceways and the first and second inner raceways depending on adjustment of the distance between the first and second

inner raceways, thus conducting planetary motion; and a compression unit coupled to an inner surface of the cylindrical body and disposed in front of the speed change unit. Here, one of the first and second inner raceways which is disposed adjacent to the input unit may be integrated with an input shaft of the input unit.

The first and second inner raceways may be respectively integrally provided on the input shaft and an output shaft of the output unit.

The compression unit may include a support member fastened to the cylindrical body, and an elastic member provided between the support member and the speed change unit. The gearshift control unit may include: a cylindrical body fastened to a circumferential inner surface of the housing; the first and second outer raceways provided on a circumferential inner surface of the cylindrical body, wherein one of the first and second outer raceways is integrated with the cylindrical body, and a remaining one of the first and second outer raceways is threaded into the circumferential inner surface of the cylindrical body; a tubular shaft to which an input shaft of the input unit is fastened; the first and second inner raceways coupled to the tubular shaft so as to be rotatable along with the tubular shaft, the first and

second inner raceways being provided around a circumferential outer surface of the input unit, each of the first and second inner raceways having an annular shape, wherein one of the first and second inner raceways is integrated with the tubular shaft, and a remaining one of the first and second inner raceways is coupled to the tubular shaft so as to be movable; the rotary members provided between the first and second outer raceways and the first and second inner raceways, wherein the rotary members are in contact with the first and second outer raceways and the first and second inner raceways depending on adjustment of the distance between the first and second inner raceways, thus conducting planetary motion; and a speed control unit surrounding an outer circumference of the input unit having an elastic member for compressing the first and second inner raceways, with a worm wheel provided around an outer circumference of the speed control unit, the worm wheel engaging with a worm gear.

The continuously variable transmission may further include a fastening unit having a fastening pin for coupling the worm wheel to one of the first and second outer raceways .

The first and second outer raceways may be coupled to an inner circumference of the housing. One of the first and second outer raceways may be coupled to the housing using a key so as to be movable in a horizontal

direction, and a remaining one of the first and second outer raceways may engage with a thread formed in a circumferential inner surface of the housing. The continuously variable transmission may further include a tubular shaft to which an input shaft of the input unit is fastened, wherein the first and second inner raceways are fastened to a circumferential outer surface of the tubular shaft, wherein one of the first and second inner raceways may be integrated with the tubular shaft, and a remaining one of the first and second inner raceways may be threaded over the circumferential outer surface of the tubular shaft.

The first and second outer raceways may be coupled to an inner circumference of the housing. The first and second outer raceways may be coupled to the housing using a key so as to be movable in a horizontal direction. The continuously variable transmission may further include a tubular shaft to which an input shaft of the input unit is fastened, wherein one of the first and second inner raceways may be threaded over a circumferential outer surface of the tubular shaft, and a remaining one of the first and second inner raceways may be integrated with the tubular shaft .

Here, a coupling part having a thread may be provided on a circumferential outer surface of one of the first and second outer raceways which is disposed adjacent

to the output unit. The coupling part may be threaded to a worm wheel .

The continuously variable transmission may further include a speed control unit provided adjacent to the output unit, with a worm wheel provided around an outer circumference of the speed control unit, the worm wheel engaging with a worm gear.

Here, the worm wheel may be connected to one of the first and second outer raceways using a pin such that the worm wheel is operated in conjunction with the corresponding outer raceway.

Furthermore, a coupling part may be provided on one of the first and second outer raceways and fastened to the worm wheel using a key. Meanwhile, a support member may be fastened to the circumferential inner surface of the cylindrical body by one of a threaded coupling method or a force-fitting method.

The continuously variable transmission may further include a speed control unit, having: a mounting pipe coupled to the output unit, with the first and second inner raceways provided around one end of the mounting pipe; a rotating pipe provided around a circumferential outer surface of the mounting pipe, the rotating pipe coupled at a first end thereof to one of the first and second inner raceways, with a worm wheel provided around a

second end of the rotating pipe; a gearshift shaft having a worm gear engaging with the worm wheel, the gearshift shaft extending a predetermined length such that opposite ends thereof protrude outside of the housing; and a motor connected to one of the opposite ends of the gearshift shaft.

The speed change unit may include: a cylindrical body fastened to an inner circumference of the housing; the first and second outer raceways fastened in the cylindrical body; the first and second inner raceways provided inside the first and second outer raceways at positions corresponding to each other; and a tubular shaft to which an input shaft of the input unit is fastened, wherein one of the first and second inner raceways is threaded over a circumferential outer surface of the tubular shaft, and a remaining one of the first and second inner raceways is integrated with the tubular shaft.

The speed change unit may include: an inner casing installed in the housing, with a first gear provided on a circumferential outer surface of the inner casing; a cylindrical body fastened in the inner casing; the first and second inner raceways provided inside the first and second outer raceways at positions corresponding to each other; and a support shaft provided in the inner casing, the support shaft being fastened at one end thereof to the housing, wherein one of the first and second inner

raceways is threaded over a circumferential outer surface of the support shaft, and a remaining one of the first and second inner raceways is integrated with the support shaft. The speed change unit may include: an inner casing installed in the housing; a cylindrical body fastened in the inner casing; the first and second inner raceways provided inside the first and second outer raceways at positions corresponding to each other; and a support shaft provided in the inner casing, the support shaft being fastened at one end thereof to the housing, wherein one of the first and second inner raceways is threaded over a circumferential outer surface of the support shaft, and a remaining one of the first and second inner raceways is integrated with the support shaft.

Here, the first inner raceway may have an extension having a predetermined length, and a speed control unit may be provided on an outer circumference of the extension of the first inner raceway. The speed control unit may include a worm wheel engaging with a worm gear.

Furthermore, the input unit may include: a connection pipe supported at opposite ends thereof by the housing, the connection pipe having a first gear disposed adjacent to the inner casing, with a second gear engaging with the first gear; and an input shaft fastened to the connection pipe to rotate the connection pipe.

The continuously variable transmission may further include an electric motor to operate the speed change unit using external power, the electric motor including a rotor fastened to the inner casing, and a stator fastened to a circumferential inner surface of the housing and provided around the rotor.

The input unit may include an input shaft protruding outside of the housing, and a connection part integrally provided on the input shaft and disposed in the housing, so that input unit transmits the external power to the gearshift control unit.

The output unit may include: an output shaft coaxially provided with the input unit, such that a first end of the output shaft protrudes outside of the housing and a second end thereof is movably coupled to the input unit; and a flange provided on the second end of the output shaft, the flange having power transmission arms extending between the rotary members .

The flange may be integrally provided on the output shaft of the output unit.

Here, a roller may be provided on each of the power transmission arms of the flange. The roller may be in contact with the corresponding rotary members .

Furthermore, a contact member may protrude from each of the power transmission arms of the flange. The contact member may contact and support the corresponding

rotary members .

[Advantageous Effects]

In the present invention having the above-mentioned construction, power transmission between rotary members and raceways using frictional force therebetween can be precisely adjusted by controlling a worm wheel and a worm gear. Thus, output rotating force (changes in speed) can be controlled.

Furthermore, even while shifting gears, rotating speed and revolution speed of the rotary members which conduct planetary motion can be precisely controlled by adjusting a distance between the raceways using the worm wheel and the worm gear.

In addition, even when the speed is controlled, an elastic member maintains elastic force constant, so that torque can be maintained constant. As well, the present invention has a function as a clutch. Thus, a separate clutch is not required, thereby reducing the volume and weight of the transmission. Moreover, the transmission of the present invention can be simply connected to various types of input or output units, so that it can be used for a variety of purposes.

The transmission of the present invention further includes a speed control unit for controlling speed, so that it can be used for controlling the speed of a device

of large capacity, and output which is precisely changed in speed can be obtained.

[Description of Drawings]

FIG. 1 is a sectional view illustrating a continuously variable transmission, according to a first embodiment of the present invention;

FIG. 2 is a sectional view taken along the line A-A of FIG. 1;

FIG. 3 is a plan view of the continuously variable transmission according to the first embodiment of the present invention;

FIGS. 4a and 4b are enlarged views showing a method for controlling gearshift according to the first embodiment; FIG. 5 is a view showing another example of a rotary member according to the present invention;

FIG. 6 is a sectional view showing the rotary members of FIG. 5;

FIG. 7 is a sectional view illustrating a continuously variable transmission, according to a second embodiment of the present invention;

FIG. 8 is a sectional view illustrating a continuously variable transmission, according to a third embodiment of the present invention; FIG. 9 is a sectional view illustrating a

continuously variable transmission, according to a fourth embodiment of the present invention;

FIG. 10 is a sectional view illustrating a continuously variable transmission, according to a fifth embodiment of the present invention;

FIG. 11 is a view showing another example of a rotary member according to the fifth embodiment of the present invention;

FIG. 12 is a view showing a further example of a rotary member according to the fifth embodiment of the present invention;

FIG. 13 is a view showing yet another example of a rotary member according to the fifth embodiment of the present invention; FIG. 14 is a view showing still another example of a rotary member according to the fifth embodiment of the present invention;

FIG. 15 is a view showing still another example of a rotary member according to the fifth embodiment of the present invention;

FIG. 16 is a view showing still another example of a rotary member according to the fifth embodiment of the present invention;

FIG. 17 is a sectional view illustrating a continuously variable transmission, according to a sixth embodiment of the present invention;

FIG. 18 is a sectional view illustrating a continuously variable transmission, according to a seventh embodiment of the present invention; and

FIG. 19 is a sectional view illustrating a continuously variable transmission, according to an eighth embodiment of the present invention.

[Best Mode]

Hereinafter, a continuously variable transmission according to the present invention will be described in detail with reference to the attached drawings. [First embodiment]

FIG. 1 is a sectional view illustrating a continuously variable transmission, according to a first embodiment of the present invention. FIG. 2 is a sectional view taken along the line A-A of FIG. 1. FIG. 3 is a plan view of the continuously variable transmission according to the first embodiment of the present invention.

As shown in FIGS. 1 through 3, the continuously variable transmission 10 according to the first embodiment of the present invention includes a housing 100 which has a cylindrical structure which has an internal space 102 therein and is open on the opposite ends thereof. The open ends of the cylindrical housing 100 are covered with covers 110. The continuously variable transmission 10 further

includes a gearshift control unit 200 which is installed in the internal space 102 of the housing 100 and controls the speed of the transmission using external power.

The gearshift control unit 200 includes a cylindrical body 210 which has a cylindrical shape and is open on opposite ends thereof. Furthermore, a stop protrusion 212 is provided on the circumferential inner surface of the cylindrical body 210. In addition, a depression 214 is formed in the circumferential inner surface of the cylindrical body 210 at a position adjacent to the stop protrusion 212. An internal thread 216 having a predetermined depth is formed in a portion of the circumferential inner surface of the cylindrical body 210 which is outside the areas of the stop protrusion 212 and the depression 214.

Furthermore, a speed change unit 220 is installed in the cylindrical body 210 to change the speed of the transmission.

The speed change unit 220 includes first and second outer annular raceways 221 and 221a which respectively have convex inner surfaces 222 and 222a having arc-shaped cross-sections. The first and second outer raceways 221 and 221a are installed in the depression 214 using a retaining bar 218 such that they can be rotated along with the cylindrical body 210.

Here, the first outer raceway 221 is closely

fastened to the stop protrusion 212 of the cylindrical body 210 and is thus prevented from moving. The second outer raceway 221a is provided such that it is movable on the depression 214 of the cylindrical body 210 in the longitudinal direction of the cylindrical body 210 under the guidance of the retaining bar 218.

The speed change unit 220 further includes first and second inner annular raceways 223 and 223a which respectively have outer diameters less than the inner diameters of the first and second outer raceways 221 and 221a. Convex surfaces 224 and 224a are respectively formed on the circumferential outer surfaces of the first and second inner raceways 223 and 223a. Furthermore, the first and second inner raceways 223 and 223a are threaded to each other such that they can approach and move away from each other.

In detail, the convex surfaces 224 and 224a are respectively formed in the first and second inner raceways 223 and 223a at positions adjacent to each other and corresponding to the convex surfaces 222 and 222a of the first and second outer raceways 221 and 221a. Therefore, when the first and second outer raceways 221 and 221a and the first and second inner raceways 223 and 223a are installed in the cylindrical body 210, the convex surfaces 222, 222a, 224 and 224a form a "+" shape. When one of the first and second inner raceways 223 and 223a rotates, the

first and second inner raceways 223 and 223a approach or move away from each other because of the threaded coupling structure.

A plurality of protrusions 223b is provided on one surface of one of the first and second inner raceways 223 and 223a. It is preferable that the protrusions 223b are provided on the first inner raceway 223a.

Furthermore, a plurality of rotary members 226, which have high hardness and stiffness, is installed in an annular space that is formed by the convex surfaces 222, 222a, 224 and 224a of the first and second outer raceways 221 and 221a and the first and second inner raceways 223 and 223a.

Here, each of the rotary members 226 includes a rod-shaped rotary member body 22βa. Conical contact surfaces 22βb are formed on opposite ends of the rotary member body 226a.

The contact surfaces 226b have concave shapes corresponding to the convex surfaces 222, 222a, 224 and 224a of the first and second outer raceways 221 and 221a and the first and second inner raceways 223 and 223a.

Meanwhile, a compression unit 230 is installed in the cylindrical body 210 and disposed in front of the speed change unit 220. The compression unit 230 includes an elastic member

232 which is in contact with the side of the second outer

raceway 221a and elastically compresses the second outer raceway 221a towards the first outer raceway 221. The compression unit 230 further includes a support member 234 which has an external thread 235 on the circumferential outer surface thereof and is threaded to the circumferential inner surface of the cylindrical body 210 to support the elastic member 232.

Preferably, the elastic member 232 is formed by overlapping several disk-shaped springs (disk springs) , the central portions of which protrude in one direction, in order to ensure high elasticity. However, the elastic member 232 is not limited to the disk springs, and any spring can be used as the elastic member 232, so long as it has relatively high elasticity. Furthermore, in the present invention, a speed control unit 240, a portion of which is coupled to the speed change unit 220, is provided in front of the compression unit 230.

The speed control unit 240 includes a mounting pipe 242 and a rotating pipe 244. The first and second inner raceways 223 and 223a are seated onto the circumferential outer surface of a first end of the mounting pipe 242. The rotating pipe 244 surrounds the circumferential outer surface of the mounting pipe 242. In order to movably couple the rotating pipe 244 to the mounting pipe 242, the support member 234 is coupled to the circumferential outer

surface of the rotating pipe 244, and protrusions 244a which alternate with the protrusions 223b of the second inner raceway 223a are provided on the rotating pipe 244. As well, a worm wheel 245 is provided on the circumferential outer surface of a second end of the rotating pipe 244.

In addition, the speed control unit 240 further includes a worm gear 246 which engages with the worm wheel 245 of the rotating pipe 244. A gearshift shaft 247 which protrudes outside of the housing 100 is provided on the two opposite ends of the worm gear 246. A motor 248 for rotating the rotating pipe 244 is coupled to one end of the gearshift shaft 247.

As well, an input unit 300 is provided on a longitudinal center axis of the housing 100, so that external power is input to the gearshift control unit 200 through the input unit 300 to rotate the cylindrical body 210.

Here, the input unit 300 includes an input shaft part 310, which is supported by the corresponding cover 110 of the housing 100. One end of the input shaft part 310 extends outside and is coupled to a drive unit (not shown) which is separately provided outside of the transmission. The input unit 300 further includes a connection part 320 which is disposed in the housing 100 and is coupled to the cylindrical body 210 using a

coupling means.

Furthermore, an output unit 400 is coaxially provided at a position opposite the input unit 300. Power input from the input unit 300 is output through the output unit 400 after it is changed in speed in the gearshift control unit 200.

Here, the output unit 400 comprises an output shaft 410 which is fitted into the mounting pipe 242. One end of the output shaft 410 extends outside of the housing 100, and the other end thereof is rotatably coupled to the input unit 300.

Furthermore, a flange 420 is provided on the output shaft 410 at a predetermined position adjacent to the input 300, so that the output shaft 410 is connected to the speed change unit 220 through the flange 420.

The flange 420 includes a plurality of power transmission arms 422 which extend between the rotary members 226 that are installed in the convex surfaces 222, 222a, 224 and 224a of the first and second outer raceways 221 and 221a and the first and second inner raceways 223 and 223a of the speed change unit 220. A roller 424 which is in rolling contact with side contact surfaces 226a of the corresponding rotary members 226 is provided on the end of each power transmission arm 422. Therefore, when the cylindrical body 210 and the first and second outer raceways 221 and 221a are rotated

by power input from the input unit 300, the rotary members 226 planetarily move around the first and second inner raceways 223 and 223a along the convex surfaces 224 and 224a thereof. Then, power changed in speed by contact between the rotary members 226 and the convex surfaces 222, 222a, 224 and 224a is output through the flange 420 and the output shaft 410.

Meanwhile, oil is charged into space in the cylindrical body 210. For this, oil passages 243 are formed between the mounting pipe 242 and the rotating pipe 244. Preferably, the oil passages 243 are formed in the outer surface of the mounting pipe 242.

Furthermore, in the continuously variable transmission 10, bearings are preferably provided between the elements that are rotatably coupled to each other, thus making the rotation of the elements smooth. In addition, a sealing member for preventing leakage of oil is preferably provided at a position at which oil is supplied into the transmission. The operation of the continuously variable transmission according to the first embodiment of the present invention having the above-mentioned construction will be explained below.

The input shaft 310 is connected to the external drive unit (not shown) . The input shaft 310 is rotated by the drive unit.

The cylindrical body 210 and the first and second outer raceways 221 and 221a which are connected to the input shaft 310 are rotated together by the rotation of the input shaft 310. The rotary members 226, which are disposed between the convex surfaces 222 and 222a of the first and second outer raceways 221 and 221a and the convex surfaces 224 and 224a of the first and second inner raceways 223 and 223a, are planetarily moved along the convex surfaces 222, 222a, 224 and 224a. Power, which is changed in speed by the planetary movement of the rotary members 226, is output through the output shaft 410.

That is, rotating force by the planetary movement of the rotary members 226 is transmitted to the flange 420 through the power transmission arms 422, thus rotating the flange 420. Then, the output shaft 410 is rotated by the rotation of the flange 420. As a result, power changed in speed is output outside of the transmission.

Therefore, in the first embodiment of the present invention, desired torque and speed can be obtained in such a way that the elastic member 232 is compressed or loosened by moving the support member 234 threaded to the cylindrical body 210.

The continuously variable transmission of the present invention is operated by the above-mentioned motion of the elements thereof. The gearshift of the

continuously variable transmission will be explained below.

FIGS. 4a and 4b are enlarged views showing a method for controlling the gearshift of the continuously variable transmission according to the first embodiment of the present invention.

As shown in FIG. 4a, in the state in which the rotary members 226 planetarily move between the first and second outer raceways 221 and 221a and the first and second inner raceways 223 and 223a, when the motor 248 of the speed control unit 240 is operated, the gearshift shaft 247 is rotated. Then, the rotating pipe 244 rotates in one direction along the circumferential outer surface of the mounting pipe 242 because of engagement between the worm gear 246 and the worm wheel 245.

At this time, the second inner raceway 223a rotates, because the protrusions 223b provided on the second inner raceway 223a are alternately coupled to the protrusions 224a provided on the rotating pipe 244. As such, when the second inner raceway 223a rotates, the second inner raceway 223a moves towards the first inner raceway 223, because they are threaded to each other. Thereby, a distance between the first and second inner raceways 223 and 223a is reduced. Furthermore, as shown in FIG. 4b, when a distance between the first and second outer raceways 221 and 221a

is increased by adjusting the compression unit 230, contact positions between the rotary members 226 and the outer and inner raceways 221, 221a, 223 and 223a are changed from Pl to P2. Therefore, the revolution trajectory of the rotary members 226, each of which perform planetary motion, that is, the revolution around the center axis of the transmission and the rotation on its own axis, is reduced, so that the rotating speed of the rotary members 226 is reduced. The rotation of the rotary members 226 which has been reduced in speed is transmitted to the output shaft 410 through the power transmission arms 422. Therefore, the speed of the output shaft 410 is reduced. Meanwhile, the gearshift operation for increasing speed can be implemented by adjusting the positions of the rotary members 226 in the direction opposite that of the above-mentioned gearshift operation for reducing speed.

Meanwhile, the interior of the cylindrical body 210 is filled with oil. Thus, the contact surfaces between the rotary members 226 and the outer and inner raceways 221, 221a, 223 and 223a are coated with the oil. Therefore, sufficient frictional force is provided between the elements, so that power transmission can be reliably ensured. In addition, oil is injected into the cylindrical body 210 through one of the two oil passages 243 which are formed in the outer surface of the mounting

pipe 242, and the oil is discharged from the cylindrical body 210 through the remaining one of the two oil passages 243. Hence, replacement of oil and the operation of cooling the rotary members 226 and the outer and inner raceways 221, 221a, 223 and 223a can be conducted at the same time. Thereby, power loss is prevented from occurring due to variation in physical properties of the oil. As well, the rotary members 226 and the outer and inner raceways 221, 221a, 223 and 223a can be cooled despite not using a separate cooling device.

FIG. 5 is a view illustrating another example of the rotary member, according to the present invention. FIG. 6 is a sectional view illustrating the rotary members of FIG. 5. As shown in FIGS. 5 and 6, in the continuously variable transmission 10 of the present invention, each of the rotary members 226 which are seated into seating holes 422a of power transmission arms 422 provided on the flange 420 includes a rotary member body 22βa which has a rod shape and has a space 22 βc in a medial portion thereof. The rotary member 226 further includes a central shaft 226d which is provided in the space 226c of the rotary member body 22 βa, and a roller 226e which is provided on the central shaft 22βd. Conical contact surfaces 22βb are formed on the opposite ends of the rotary member body 226a. Each of the contact surfaces 22βb has a concave

shape .

The diameter of the roller 22βe is greater than that of the rotary member body 22βa such that the outer surface of the roller 22βe protrudes outside of the rotary member body 226a.

Furthermore, contact members 422b protrude into the seating holes 422a of the power transmission arms 422 of the flange 420. The roller 266e is in contact with the opposite surfaces of the corresponding contact members 422b in the direction in which the rotary members 266 are rotated.

The operation of the continuously variable transmission of this example having the above-mentioned construction is almost the same as that of the prior embodiment, therefore further explanation is deemed unnecessary.

Only, the rollers 736 of the rotary members 730 are in rolling contact with the contact members 342a of the power transmission members 342 of the flange 340, thus operating the flange 340.

Therefore, power changed in speed by the rotary members 730 is output outside through the flange 340 and the output shaft 410.

[Second embodiment] FIG. 7 is a sectional view illustrating a continuously variable transmission, according to a second

embodiment of the present invention.

As shown in FIG. 7, the continuously variable transmission 10a according to the second embodiment of the present invention includes a housing 1100 which has a cylindrical structure which has an internal space 1102 therein and is open on the opposite ends thereof. One of the open ends of the cylindrical housing 1100 is covered with a cover 1110, and a remaining one is covered with a support member 1234. The support member 1234 is threaded into the circumferential inner surface of the housing 1100. Therefore, the support member 1234 moves in the longitudinal direction of the housing 1100 depending on tightening or loosening of the support member 1234 into or from the housing 1100.

The continuously variable transmission 10a further includes a gearshift control unit 1200 which is installed in the internal space 1102 of the housing 1100 and controls the speed of the transmission using external power.

The gearshift control unit 1200 includes a cylindrical body 1210 which has a cylindrical shape and is open on the opposite ends thereof. A depression 1214 is formed in a first end of the circumferential inner surface of the cylindrical body 1210. A thread 1216 is formed in a second end of the circumferential inner surface of the

cylindrical body 1210. The cylindrical body 1210 is. fastened to the circumferential inner surface of the housing 1100.

Furthermore, a speed change unit 1220 is installed in the cylindrical body 1210 to change the speed of the transmission.

The speed change unit 1220 includes a first outer annular raceway 1221 which has a convex inner surface 1222 having an arc-shaped cross-section. The first outer raceway 1221 is installed in the depression 1214 using a retaining bar 1218 such that the first outer raceway 1221 can be rotated along with the cylindrical body 1210.- The speed change unit 1220 further includes a second outer annular raceway 1221a which has a convex inner surface 1222a having an arc-shaped cross-section and corresponds to the first outer raceway 1221 and is threaded into the circumferential inner surface of the cylindrical body 1210.

In other words, the first outer raceway 1221 is fastened to the depression 1214 of the cylindrical body 1210 using the retaining bar 1218 such that it is stationary. The second outer raceway 1221a is threaded into the circumferential inner surface of the cylindrical body 1210 so as to be movable in the longitudinal direction of the cylindrical body 1210.

The speed change unit 1220 further includes first

and second inner annular raceways 1223 and 1223a which respectively have outer diameters less than the inner diameters of the first and second outer raceways 1221 and 1221a. Convex surfaces 1224 and 1224a are respectively formed on the circumferential outer surfaces of the first and second inner raceways 1223 and 1223a. Furthermore, the first and second inner raceways 1223 and 1223a are constructed such that they can approach and move away from each other. Of the first and second inner raceways, the first inner raceway 1223 is coupled to an input shaft 1310 and fastened to a tubular shaft 1314 which is installed along the center axis of the housing 1100. The second inner raceway 1223a is coupled to the circumferential outer surface of the tubular shaft 1314 using a retaining bar 1316 so as to be movable in the longitudinal direction of the tubular shaft 1314.

Furthermore, a plurality of rotary members 1226 having high hardness and stiffness is installed between the first and second outer raceways 1221 and 1221a and the first and second inner raceways 1223 and 1223a.

Here, each rotary member 1226 includes a rod-shaped rotary member body 1226a. Conical contact surfaces 1226b are formed on opposite ends of the rotary member body 1226a. The conical contact surfaces 1226b are in contact with the convex surfaces 1222, 1222a, 1224 and 1224a of

the first and second outer raceways 1221 and 1221a and the first and second inner raceways 1223 and 1223a.

The contact surfaces 1226b of the rotary member

1226 have concave shapes corresponding to the convex surfaces 1222, 1222a, 1224 and 1224a of the first and second outer raceways 1221 and 1221a and the first and second inner raceways 1223 and 1223a.

Meanwhile, a compression unit 1230 which compresses the second inner raceway 1223a of the speed change unit 1220 is installed in the cylindrical body 1210.

The compression unit 1230 includes an elastic member 1232 which is in contact with the side of the second inner raceway 1223a and elastically compresses the second inner raceway 1223a towards the first inner raceway 1223. The elastic member 1232 is supported by the support member 1234.

Preferably, the elastic member 1232 is formed by overlapping several disk-shaped springs (disk springs) , the central portions of which protrude in one direction, in order to ensure high elasticity. However, the elastic member 1232 is not limited to the disk springs, and any spring can be used as the elastic member 1232, so long as it has relatively high elasticity.

Furthermore, a speed control unit 1240 is connected to the speed change unit 1220 and disposed outside of the compression unit 1230.

The speed control unit 1240 includes a worm wheel 1245 which is provided between the first and second outer raceways 1221 and 1221a, the first and second inner raceways 1223 and 1223a and the support member 1234 and has a shape surrounding the elastic member 1232. A worm gear 1246 which protrudes outside of the sidewall of the housing 1100 engages with the worm wheel 1245. The worm gear 1246 is provided on a gearshift shaft 1247 which is coupled at one end thereof to a motor. Furthermore, the support member 1234, the worm gear

1246 and the outer raceway 1221a are coupled to each other by a pin 1235.

In detail, through holes 1234a and 1246a are respectively formed in the support member 1234 and the worm gear 1246 in the same line. An insert hole 1221b is formed in the second outer raceway 1221a at a position corresponding to the through holes 1234a and 1246a. The pin 1235 is fitted into the through holes 1234a and 1246a and the insert hole 1221b. Thereby, the support member 1234, the worm gear 1246 and the outer raceway 1221a are fastened to each other.

The continuously variable transmission further includes an input unit 1300 which is fastened to the tubular shaft 1314 provided along the central axis of the housing 1100. The input unit 1300 transmits external power to the gearshift control unit 1200.

Here, the input unit 1300 includes an input shaft part 1310, which is coupled to the tubular shaft 1314, and one end of which extends outside and is coupled to a drive unit (not shown) which is separately provided outside of the transmission.

Furthermore, an output unit 1400 is coaxially provided at a position opposite the input unit 1300. Power input from the input unit 1300 is output through the output unit 1400 after it is changed in speed in the gearshift control unit 1200.

Here, the output unit 1400 is coupled to the cover 1110. One end of the output unit 1400 extends outside of the housing 1100, and the other end thereof is disposed in the housing 1100. Furthermore, a flange 1420 is provided on one end of an output shaft 1410 of the output unit 1400 at a position adjacent to the input 1300, so that the output shaft 1410 is connected to the speed change unit 1220 through the flange 420. The flange 1420 includes a plurality of power transmission arms 1422 which extend between the rotary members 1226 that are installed between the first and second outer raceways 1221 and 1221a and the first and second inner raceways 1223 and 1223a of the speed change unit 1220. A roller 1424 which is in rolling contact with the outer surfaces of the member bodies 1226a of the

corresponding rotary members 1226 is provided on the end of each power transmission arm 1422.

Therefore, when the tubular shaft 1314 is rotated by power input into the input unit 1300, the first and second inner raceways 1223 and 1223a also rotate. The rotary members 1226 conduct planetary motion because of the rotation of the first and second inner raceways 1223 and 1223a. Then, power changed in speed by contact between the rotary members 1226 and the first and second inner raceways 1223 and 1223a is output through the flange 1420 and the output shaft 1410.

The operation, that is, the shifting method, of the continuously variable transmission according to the second embodiment having the above-mentioned construction is the same as that of the first embodiment, therefore further explanation will be skipped.

Only, unlike the first embodiment, in the second embodiment, power input into the input shaft 1310 rotates the first and second inner raceways 1223 and 1223a through the tubular shaft 1314, so that the rotary members 1226 revolve round the center axis of the transmission and rotate their own axes. To control torque, when the worm gear 1246 is rotated in one direction, the support member 1234 and the second outer raceway 1221a which are coupled to each other by the pin 1234a are threadedly moved towards the output unit 1400 by the rotation of the worm

wheel 1245. When the worm gear 1246 is rotated in the reverse direction, the support member 1234 and the second outer raceway 1221a are threadedly moved towards the input shaft 1310. The torque of the transmission can be controlled by the above-mentioned operation. To move the second inner raceway 1221a towards the output unit 1400, after the pin 1234a is completely removed from the second outer raceway 1221a, the worm gear 1246 is rotated such that the support member 1234 is moved towards the output unit 1400. Then, the second inner raceway 1223a can be moved towards the output unit 1400.

In addition, the high speed torque and the low speed torque can be embodied. As well, because the support member 1234 is threaded to the housing 1100 such that it is operated in conjunction with the worm wheel 1245 through the pin 1235, a pressure at which the support member 1234 compresses the elastic member 1232 can be adjusted when controlling the torque of the transmission. [Third embodiment]

FIG. 8 is a sectional view illustrating a continuously variable transmission, according to a third embodiment of the present invention.

As shown in FIG. 8, the continuously variable transmission 10b according to the third embodiment of the present invention includes a housing 2100 which has a

cylindrical structure which has an internal space 2102 therein and is open on the opposite ends thereof. One open end of the cylindrical housing 2100 is covered with a cover 2110. Furthermore, a speed change unit 2220 is installed in the internal space 2102 of the housing 2100 to change the speed of power transmitted from the outside.

The speed change unit 2220 includes first and second outer annular raceways 2221 and 2221a which include convex inner surfaces 2222 and 2222a having arc-shaped cross-sections. The first and second outer raceways 2221 and 2221a are installed using a retaining bar 2106 in a depression 2104 which is formed in the circumferential inner surface of the housing 2100 in the longitudinal direction of the housing 2100. The first and second outer raceways 2221 and 2221a are threaded to each other.

In other words, the first outer raceway 2221 is fastened to the circumferential inner surface of the housing 2100 using the retaining bar 2106. The second outer raceway 2221a is threaded into the circumferential inner surface of the first outer raceway 2221 so as to be threadedly movable in the longitudinal direction of the housing 2100.

The speed change unit 2220 further includes first and second inner annular raceways 2223 and 2223a which respectively have outer diameters less than the inner

diameters of the first and second outer raceways 2221 and 2221a. Convex surfaces 2224 and 2224a are respectively formed on the circumferential outer surfaces of the first and second inner raceways 2223 and 2223a. Furthermore, the first and second inner raceways 2223 and 2223a are provided around the circumferential outer surface of a tubular shaft 2314 which is provided in the housing 2100 adjacent to an input unit 2300.

Here, the first inner raceway 2223 is threaded over the circumferential outer surface of the tubular shaft 2314 so as to be movable in the longitudinal direction of the tubular shaft 2314. The second inner raceway 2223a may be integrally provided on the tubular shaft 2314 at a position corresponding to the first inner raceway 2223 or, alternatively, it may be coupled to the tubular shaft 2314 using a separate coupling means.

Moreover, the first inner raceway 2223 includes an elastic member 2232 which is fitted into the circumferential outer surface of the tubular shaft 2314. The first inner raceway 2223 is supported by the elastic member 2232.

When the first and second outer raceways 2221 and 2221a and the first and second inner raceways 2223 and 2223a are installed in the housing 2100, they form a "+" shape. When one of the first and second outer raceways 2221 and 2221a rotates, for example, in this embodiment,

when the second outer raceway 2221a rotates, it moves along a thread 222b of the first outer raceway 2221. Thereby, the first and second outer raceways 2221 and 2221a approach or move away from each other. Furthermore, a plurality of rotary members 2226 having high hardness and stiffness is installed between the first and second outer raceways 2221 and 2221a and the first and second inner raceways 2223 and 2223a.

Here, each rotary member 2226 includes a rod-shaped rotary member body 2226a. Conical contact surfaces 2226b are formed on opposite ends of the rotary member body 2226a. The contact surfaces 2226b have concave shapes and are in contact with the convex surfaces 2222, 2222a, 2224 and 2224a of the first and second outer raceways 2221 and 2221a and the first and second inner raceways 2223 and 2223a.

In addition, a speed control unit 2240 which operates the second outer raceway 2221a is provided between the speed change unit 2220 and the cover 2110. The speed control unit 2240 includes a worm wheel

2245, the outer surface of which engages with a worm gear 2246. The worm wheel 2245 is connected to the second outer raceway 2221a by a pin 2245a. Thus, the second outer raceway 2221a moves towards or away from the first outer raceway 2221 depending on the rotation of the worm wheel 2245.

The worm gear 2246 is formed on a gearshift shaft

2247. The opposite ends of the gearshift shaft 2247 protrude outside of the sidewall of the housing 2100. One of the opposite ends of the gearshift shaft 2247 is coupled to a motor.

Furthermore, an input unit 2300 which transmits external power to the speed change unit 2220 is fastened to the tubular shaft 2314 which is provided on the center axis of the housing 2100. Here, the input unit 2300 comprises an input shaft 2310 which is fastened to the tubular shaft 2314, and one end of it protrudes outside of the housing 2100 and is connected to a drive unit (not shown) .

As well, an output unit 2400 is provided at a position opposite the input unit 2300 to receive power from the input unit 2300 and output torque changed in speed by the speed change unit 2220.

The output unit 2400 comprises an output shaft 2410 which is coupled to the cover 2110. Here, a first end of the output shaft 2410 extends outside of the housing 2100, and a second end thereof is disposed inside the housing

2100.

Furthermore, a flange 2420 is provided on the second end of the output shaft 2410 adjacent to the input unit 2300, so that the output shaft 2410 is connected to the speed change unit 2220 through the flange 2420.

The flange 2420 includes a plurality of power transmission arms 2422 which extend between the rotary- members 2226 that are installed between the first and second outer raceways 2221 and 2221a and the first and second inner raceways 2223 and 2223a of the speed change unit 2220. A roller 2424 which is in rolling contact with the outer surfaces of the member bodies 2226a of the corresponding rotary members 2226 is provided on the end of each power transmission arm 2422. Therefore, when the tubular shaft 2314 is rotated by power input into the input unit 2300, the first and second inner raceways 2223 and 2223a also rotate. The rotary members 2226 conduct planetary motion because of the rotation of the first and second inner raceways 2223 and 2223a. Then, power changed in speed by contact between the rotary members 2226 and the first and second inner raceways 2223 and 2223a is output through the flange 2420 and the output shaft 2410.

The operation, that is, the shifting method, of the continuously variable transmission according to the third embodiment having the above-mentioned construction is the same as that of the prior embodiment (the second embodiment) , therefore further explanation is deemed unnecessary. Meanwhile, in the third embodiment, a torsion spring is used as the elastic member 2232 and fastened to

the outer surfaces of the first inner raceway 2223 and the tubular shaft 2314. Therefore, a separate element for supporting the elastic member 2232 is not required, thus increasing space utilization, in other words, reducing installation space of the elements. As a result, the continuously variable transmission 10b can have a compact structure.

[Fourth embodiment]

FIG. 9 is a sectional view illustrating a continuously variable transmission, according to a fourth embodiment of the present invention.

As shown in FIG. 9, the continuously variable transmission 10c according to the fourth embodiment of the present invention includes a housing 3100 which has an internal space 3102 therein. One open end of the housing

3100 is covered with a cover 3110.

The continuously variable transmission 10c of the fourth embodiment further includes a gearshift control unit 3200 which is installed in the internal space 3102 of the housing 3100 and controls the torque of the transmission using external power.

The gearshift control unit 3200 includes a cylindrical body 3210 which has a cylindrical shape and is open on the opposite ends thereof. A thread 3216 is formed in a first end of the circumferential inner surface of the cylindrical body 3210. A recess 3218 is formed in

a second end of the cylindrical body 3210. The cylindrical body 3210 is fastened to the circumferential inner surface of the housing 3100. Here, a depression 3104 is longitudinally formed in the circumferential inner surface of the housing 3100. Thus, the cylindrical body 3210 is fastened to the depression 3140 using a retaining bar 3106.

Furthermore, a speed change unit 3220 is installed in the cylindrical body 3210 to change speed of the torque of power input into the transmission.

The speed change unit 3220 includes first and second outer annular raceways 3221 and 3221a which include convex inner surfaces 3222 and 3222a having arc-shaped cross-sections. The first and second outer raceways 3221 and 3221a are fastened to the cylindrical body 3210.

In detail, the first outer raceway 3221 is threaded to the thread 3216 formed in the circumferential inner surface of the cylindrical body 32210. The second outer raceway 3221a is fastened to the recess 3218 of the cylindrical body 3210 using a retaining bar 3219.

The speed change unit 3220 further includes first and second inner annular raceways 3223 and 3223a which respectively have outer diameters less than the inner diameters of the first and second outer raceways 3221 and 3221a. Convex surfaces 3224 and 3224a are respectively formed on the circumferential outer surfaces of the first

and second inner raceways 3223 and 3223a such that they correspond to each other.

Here, the first inner raceway 3223 is threaded over a circumferential outer surface of a tubular shaft 3314 which is provided adjacent to an input unit 3300. The second inner raceway 3223a is firmly fastened to the circumferential outer surface of a tubular shaft 3314 using a fastening means.

Furthermore, a plurality of rotary members 3226 having high hardness and stiffness is installed between the first and second outer raceways 3221 and 3221a and the first and second inner raceways 3223 and 3223a.

Here, each rotary member 3226 includes a rod-shaped rotary member body 3226a. Conical contact surfaces 3226b are formed on opposite ends of the rotary member body 3226a. The contact surfaces 3226b are in contact with the convex surfaces 3222, 3222a, 3224 and 3224a of the first and second outer raceways 3221 and 3221a and the first and second inner raceways 3223 and 3223a. The contact surfaces 3226b of the rotary member

3226 have concave shapes corresponding to the convex surfaces 3222, 3222a, 3224 and 3224a of the first and second outer raceways 3221 and 3221a and the first and second inner raceways 3223 and 3223a. Furthermore, an elastic member 3232 elastically compresses and supports the first inner raceway 3223 of

the speed change unit 3220 which is installed in the cylindrical body 3210.

Here, the elastic member 3232 is inserted at a first end thereof into the circumferential outer surface of the tubular shaft 3314. A second end of the elastic member 3232 supports the side of the first inner raceway

3223.

In addition, a speed control unit 3240 which is coupled to the speed change unit 3220 is provided adjacent to the input unit 3300 into which power is input.

The speed control unit 3240 includes a worm wheel 3245 which is disposed outside of the elastic member 3232. A gearshift shaft 3247 is provided adjacent to the worm wheel 3245. The opposite ends of the gearshift shaft 3247 protrude outside of the sidewall of the housing 3100. One end of the gearshift shaft 3247 is coupled to a motor. A worm gear 3246 which engages with the worm wheel 3245 is formed on the circumferential outer surface of the gearshift shaft 3247. As well, a through hole 3245a is formed through the worm wheel 3245, and an insert hole 332b is formed in the first outer raceway 3221 at a position corresponding to the through hole 3245a. A pin 3245b is inserted into the through hole 3245a and the insert hole 3222b. Thus, the worm wheel 3245 and the first outer raceway 3221 are operated in conjunction with each other.

The input 3300 which transmits external power to the gearshift control unit 3240 is fastened to the tubular shaft 3314 which is provided along the center axis of the housing 3100. Here, the input unit 3300 comprises an input shaft

3310 which is fastened to the tubular shaft 3314, and one end of which protrudes outside of the housing 3100 and is connected to a drive unit (not shown) .

In addition, an output unit 3400 is provided at a position opposite the input unit 3300 to receive power from the input unit 3300 and output torque changed in speed by the gearshift control unit 3200.

The output unit 3400 comprises an output shaft 3410 which is coupled to the cover 3110. Here, a first end of the output shaft 3410 extends outside of the housing 3100, and a second end thereof is disposed inside the housing

3100.

Furthermore, a flange 3420 is provided on the second end of the output shaft 3410 adjacent to the input 3300, so that the output shaft 3410 is connected to the speed change unit 3220 through the flange 3420.

The flange 3420 includes a plurality of power transmission arms 3422 which extend between the rotary members 3226 that are installed between the first and second outer raceways 3221 and 3221a and the first and second inner raceways 3223 and 3223a of the speed change

unit 3220. A roller 3424 which is in rolling contact with the outer surfaces of the member bodies 3226a of the corresponding rotary members 3226 is provided on the end of each power transmission arm 3422. Therefore, when the tubular shaft 3314 is rotated by power input into the input unit 3300, the first and second inner raceways 3223 and 3223a also rotate. The rotary members 3226 conduct planetary motion because of the rotation of the first and second inner raceways 3223 and 3223a. Then, power changed in speed by contact between the rotary members 3226 and the first and second inner raceways 3223 and 3223a is output through the flange 3420 and the output shaft 3410.

Meanwhile, in the fourth embodiment, a torsion spring is used as the elastic member 3232 and fastened to the outer surfaces of the first inner raceway 3223 and the tubular shaft 3314. Therefore, a separate element for supporting the elastic member 3232 is not required, thus increasing space utilization, in other words, reducing installation space of the elements. As a result, the continuously variable transmission 10c can have a compact structure .

[Fifth embodiment]

FIG. 10 is a sectional view illustrating a continuously variable transmission, according to a fifth embodiment of the present invention.

As shown in FIG. 10, the continuously variable transmission 1Od according to the fifth embodiment of the present invention includes a housing 4100 which has an internal space 4102 therein and is open on the opposite ends thereof. One open end of the housing 4100 is covered with a cover 4110.

The continuously variable transmission 1Od further includes a speed change unit 4220 which is installed in the internal space 4102 of the housing 4100 to receive power transmitted from the outside and changes in speed of torque thereof.

The speed change unit 4220 includes first and second outer annular raceways 4221 and 4221a which include convex inner surfaces 4222 and 4222a having arc-shaped cross-sections. A depression 4104 is formed in the circumferential inner surface of the housing 4100 in the longitudinal direction of the housing 4100. The first and second outer raceways 4221 and 4221a are installed in the depression 4104 of the housing 4100 using a retaining bar 4106.

The speed change unit 4220 further includes first and second inner annular raceways 4223 and 4223a which respectively have outer diameters less than the inner diameters of the first and second outer raceways 4221 and 4221a. Convex surfaces 4224 and 4224a are respectively formed on the circumferential outer surfaces of the first

and second inner raceways 4223 and 4223a. Furthermore, the first and second inner raceways 4223 and 4223a are provided around the circumferential outer surface of a tubular shaft 4314 which is provided in the housing 4100 adjacent to an input unit 4300. One of the first and second inner raceways 4223 and 4223a is integrally provided on the tubular shaft 4314.

In this embodiment, the first inner raceway 4223 is provided on the circumferential outer surface of the tubular shaft 4314 so as to be movable in the longitudinal direction of the tubular shaft 4314. The second inner raceway 4223a is integrally provided on the tubular shaft 4314 at a position corresponding to the first inner raceway 4223. Here, the second inner raceway 4223a may be movably coupled to the tubular shaft 4314 using a separate coupling means (not shown) .

Furthermore, a support member 4315 is provided on the circumferential outer surface of the tubular shaft 4314. An elastic member 4323 is provided between the first inner raceway 4223 and the support member 4315 to elastically support the first inner raceway 4223.

When the first and second outer raceways 4221 and 4221a and the first and second inner raceways 4223 and 4223a are installed in the housing 4100, they form a "+" shape. One of the first and second outer raceways 4221

and 4221a, for example, in this embodiment, the second outer raceway 4221a can approach or move away from the first outer raceway 4221 under guidance of the retaining bar 4106. Furthermore, a plurality of rotary members 4226 having high hardness and stiffness is installed between the first and second outer raceways 4221 and 4221a and the first and second inner raceways 4223 and 4223a.

Here, each of the rotary members 4226 has a rod- shaped rotary member body 4226a. Conical contact surfaces 4226b are formed on opposite ends of the rotary member body 4226a. The contact surface 4226b have concave shapes and are in contact with the convex surfaces 4222, 4222a, 4224 and 4224a of the first and second outer raceways 4221 and 4221a and the first and second inner raceways 4223 and 4223a.

In addition, a speed control unit 4240 which operates the second outer raceway 4221a is provided between the speed change unit 4220 and the cover 4110. The speed control unit 4240 includes a worm wheel 4245, the outer surface of which engages with a worm gear 4246. A coupling part 4221b is provided on the second outer raceway 4221a. The worm wheel 4245a is threaded to the coupling part 4221b of the second outer raceway 4221a, so that the second outer raceway 4221a is moved towards or away from the first outer raceway 4221 by the rotation of

the worm wheel 4245a.

The worm gear 4246 is formed on a gearshift shaft

4247. The opposite ends of the gearshift shaft 4247 protrude outside of the sidewall of the housing 4100. One of the opposite ends of the gearshift shaft 4247 is coupled to a motor (not shown) .

Furthermore, an input unit 4300 is provided on the center axis of the housing 4100 to transmit external power to the speed change unit 4220. Here, the input unit 4300 comprises an input shaft 4310 which is protruded at a first end thereof outside of the housing 4100 and coupled at a second end thereof to the tubular shaft 4314.

As well, an output unit 4400 is provided at a position opposite the input unit 4300 to receive power from the input unit 4300 and output torque changed in speed by the speed change unit 4220.

The output unit 4400 comprises an output shaft 4410 which is coupled to the cover 4110. Here, a first end of the output shaft 4410 extends outside of the housing 4100, and a second end thereof is disposed inside the housing

4100.

Furthermore, a flange 4420 is provided on the second end of the output shaft 4410. The flange 4420 includes a plurality of power transmission arms 4422 which extend between the first and second outer raceways 4221

and 4221a and the first and second inner raceways 4223 and 4223a. A roller 4424 which is in rolling contact with the corresponding rotary members 4226 is provided on the end of each power transmission arm 4422. The flange 4420 is integrated with the output shaft

4410 which outputs the torque changed in speed.

Therefore, the rollers 4424 of the flange 4420 are disposed between the rotary members 4226 and thus guide the planetary motion of the rotary members 4226. Torque changed in speed by contact between the rotary members 4226 and the rollers 4424 is output through the power transmission arms 4422 of the flange 4420 and the output shaft 4410.

The operation of the continuously variable transmission of the fifth embodiment having the above- mentioned construction is the same as that of the prior embodiments, therefore further explanation is deemed unnecessary.

FIG. 11 is a view showing another example of the rotary member according to the fifth embodiment of the present invention.

As shown in the drawing, the general construction of the continuously variable transmission 1Od of FIG. 11 remains the same as that of FIG. 10. However, unlike the embodiment of FIG. 10, the rotary member 4226 includes a cylindrical rotary member body 4226a. Contact surfaces

4226b having concave shapes are formed on the opposite ends of the rotary member body 4226a. Furthermore, a space 4226c is formed in the central portion of the rotary member body 4226a. A central shaft 4226d is provided in the space 4226c. In addition, a roller 4226e is provided around the central shaft 4226d.

Here, it is preferable that the diameter of the roller 4226e be greater than that of the rotary member body 4226a. Furthermore, contact members 4422a protrude from the flange 4420. The sidewall of each contact member 4422a is in contact with the rollers 4226e of the corresponding rotary members 4226 in the direction in which the rotary members 4226 rotate. The operation of the continuously variable transmission of FIG. 11 having the above-mentioned construction is the same as that of the prior embodiment, therefore further explanation will be skipped.

Only, unlike the prior embodiments, in the embodiment of FIG. 11, the rollers 4226e of the rotary members 4226 are in rolling contact with the contact members 4422a of the flange 4420 and thus guide the planetary motion of the rotary members 4226.

Therefore, torque changed in speed by the rotary members 4226 is transmitted to the output shaft 4410 and is output to the outside of the transmission through the

output shaft 4410.

FIG. 12 is a view showing a further example of the rotary member according to the fifth embodiment of the present invention. As shown in the drawing, the general construction of the continuously variable transmission 1Od of FIG. 11 remains the same as that of FIG. 10. However, unlike the embodiment of FIG. 10, concave surfaces 4222, 4222a, 4224 and 4224a are respectively formed in facing surfaces of the first and second outer raceways 4221 and 42221a and the first and second inner raceways 4223 and 4223a.

Furthermore, the rotary member 4227 includes a cylindrical rotary member body 4227a which has contact surfaces 4227b on the opposite ends thereof. The contact surfaces 4227b are in contact with the concave surfaces 4222, 4222a, 4224 and 4224a of the first and second outer raceways 4221 and 42221a and the first and second inner raceways 4223 and 4223a. Each contact surface 4227b has a convex shape corresponding to the corresponding concave surfaces 4222, 4222a, 4224 and 4224a.

The operation of the continuously variable transmission of FIG. 12 having the above-mentioned construction is the same as that of the prior embodiment, therefore further explanation will be skipped. FIG. 13 is a view showing yet another example of a rotary member according to the fifth embodiment of the

present invention.

As shown in the drawing, the general construction of the continuously variable transmission 1Od of FIG. 13 remains the same as that of FIG. 12. However, unlike the embodiment of FIG. 12, the rotary member 4227 includes a cylindrical rotary member body 4227a. Furthermore, contact surfaces 4227b having convex shapes are formed on the opposite ends of the rotary member body 4227a. A space 4227c is formed in the central portion of the rotary member body 4227a. In addition, a central shaft 4227d is provided in the space 4227c. A roller 4227e is provided around the central shaft 4227d.

Here, it is preferable that the diameter of the roller 4227e be greater than that of the rotary member body 4227a.

Furthermore, contact members 4422a protrude from the flange 4420. The sidewall of each contact member 4422a is in contact with the rollers 4227e of the corresponding rotary members 4227 in the direction in which the rotary members 4227 rotate.

The operation of the continuously variable transmission of FIG. 13 having the above-mentioned construction is the same as that of the prior embodiment, therefore further explanation will be skipped. FIG. 14 is a view showing a still another example of the rotary member according to the fifth embodiment of

the present invention.

As shown in the drawing, the general construction of the continuously variable transmission 1Od of FIG. 14 remains the same as that of FIG. 10. In this example, concave surfaces 4222, 4222a, 4224 and 4224a are respectively formed in facing surfaces of the first and second outer raceways 4221 and 42221a and the first and second inner raceways 4223 and 4223a.

Furthermore, the rotary member 4228 includes a cylindrical rotary member body 4228a which has contact surfaces 4228b on the opposite ends thereof. The contact surfaces 4228b are in contact with the convex surfaces 4222, 4222a, 4224 and 4224a of the first and second outer raceways 4221 and 42221a and the first and second inner raceways 4223 and 4223a. Each contact surface 4228b which is in contact with the corresponding convex surfaces 4222, 4222a, 4224 and 4224a has a linear cross-section.

The operation of the continuously variable transmission of FIG. 14 having the above-mentioned construction is the same as that of the prior embodiment, therefore further explanation will be skipped.

FIG. 15 is a view showing still another example of the rotary member according to the fifth embodiment of the present invention. As shown in the drawing, the general construction of the continuously variable transmission 1Od of FIG. 15

remains the same as that of FIG. 10. However, unlike the embodiment of FIG. 10, the rotary member 4228 includes a cylindrical rotary member body 4228a. Furthermore, contact surfaces 4228b having convex shapes are formed on the opposite ends of the rotary member body 4228a. A space 4228c is formed in the central portion of the rotary member body 4228a. In addition, a central shaft 4228d is provided in the space 4228c. A roller 4228e is provided around the central shaft 4228d. Here, it is preferable that the diameter of the roller 4228e be greater than that of the rotary member body 4228a.

Furthermore, contact members 4422a protrude from the flange 4420. The sidewall of each contact member 4422a is in contact with the rollers 4228e of the corresponding rotary members 4228 in the direction in which the rotary members 4228 rotate.

The operation of the continuously variable transmission of FIG. 15 having the above-mentioned construction is the same as that of the prior embodiment, therefore further explanation will be skipped.

FIG. 16 is a view showing still another example of the rotary member according to the fifth embodiment of the present invention. As shown in the drawing, the general construction of the continuously variable transmission 1Od of FIG. 16

remains the same as that of FIG. 10. In this example, concave surfaces 4222, 4222a, 4224 and 4224a are respectively formed in facing surfaces of the first and second outer raceways 4221 and 42221a and the first and second inner raceways 4223 and 4223a.

The rotary members 4228 are disposed between the first and second outer raceways 4221 and 42221a and the first and second inner raceways 4223 and 4223a. Each rotary member 4228 has a spherical ball shape which is in contact with the concave surfaces 4222, 4222a, 4224 and 4224a, and conducts planetary motion.

The operation of the continuously variable transmission of FIG. 16 having the above-mentioned construction is the same as that of the prior embodiment, therefore further explanation will be skipped. [Sixth embodiment]

FIG. 17 is a sectional view illustrating a continuously variable transmission, according to a sixth embodiment of the present invention. As shown in the drawing, the continuously variable transmission 1Oe according to the sixth embodiment of the present invention includes a housing 5100 which has an internal space 5102 therein and is open on opposite ends thereof. The opposite open ends of the housing 5100 are covered with respective covers 5110.

Furthermore, a cylindrical body 5120 is installed

in the internal space 5102 of the housing 5100. Here, the cylindrical body 5120 is fastened to the circumferential inner surface of the housing 5100 using a retaining bar 5122. Bent parts 5120a which extend predetermined lengths inwards are provided on the opposite ends of the cylindrical body 5120.

In addition, a speed change unit 5220 is installed in the cylindrical body 5210 of the housing 5100 to receive power transmitted from the outside and change in the speed of torque thereof.

The speed change unit 5220 includes first and second outer annular raceways 5221 and 5221a which include convex inner surfaces 5222 and 5222a having arc-shaped cross-sections. The first and second outer raceways 5221 and 5221a are fastened to the circumferential inner surface of the cylindrical body 5210 using a retaining bar 5104.

Furthermore, an elastic member 5323 which is supported by one bent part 5120a of the cylindrical body 5120 is provided between the second outer raceway 5221a and the bent part 5120a of the cylindrical body 5120 in order to elastically support the second outer raceway 5221a.

The speed change unit 5220 further includes first and second inner annular raceways 5223 and 5223a which respectively have outer diameters less than the inner

diameters of the first and second outer raceways 5221 and 5221a. Convex surfaces 5224 and 5224a are respectively formed on the circumferential outer surfaces of the first and second inner raceways 5223 and 5223a. The first and second inner raceways 5223 and 5223a are provided around a circumferential outer surface of a tubular shaft 5314 which is provided adjacent to an input unit 5300 such that a portion of the tubular shaft 5314 protrudes outside of the housing 5100. One of the first and second inner raceways 5223 and 5223a is integrally provided around the tubular shaft 5314, and a remaining one is threaded over the circumferential outer surface of the tubular shaft 5314 such that one end thereof protrudes outside of the corresponding cover 5110. In this embodiment, the first inner raceway 5223 is threaded over the circumferential outer surface of the tubular shaft 5314 in the longitudinal direction of the tubular shaft 5314. The second inner raceway 5223a is integrally provided on the tubular shaft 5314 at a position corresponding to the first inner raceway 5223.

Here, the second inner raceway 5223a may be movably coupled to the tubular shaft 5314 using a separate coupling means (not shown) .

When the first and second outer raceways 5221 and 5221a and the first and second inner raceways 5223 and 5223a are installed in the housing 5100, they form a "+"

shape. When one of the first and second inner raceways 5223 and 5223a, for example, in this embodiment, when the first inner raceway 5223 rotates, the second inner raceway 5223a can threadedly move towards or away from the first inner raceway 5223.

Furthermore, a plurality of rotary members 5226 having high hardness and stiffness is installed between the first and second outer raceways 5221 and 5221a and the first and second inner raceways 5223 and 5223a. Each rotary member 5226 includes a cylindrical rotary member body 5226a. Contact surfaces 5226b having concave shapes are formed on the opposite ends of the rotary member body 5226a. A space 5226c is formed in the central portion of the rotary member body 5226a. A central shaft 5226d is provided in the space 5226c. A roller 5226e is provided around the central shaft 5226d.

Preferably, the diameter of the roller 5226e is greater than that of the rotary member body 5226a.

In addition, a speed control unit 5240 is provided around the first inner raceway 5223 of the speed change unit 5220. In detail, the speed control unit 5240 is provided around the circumferential outer surface of the outer end of the first inner raceway 5223 that protrudes outside of the housing 5100. The speed control unit 5240 includes a worm wheel

5245a which is provided on the circumferential outer

surface of the outer end of the first inner raceway 5223, and a worm gear 5246 which engages with the worm wheel 5245a. Thus, when the worm gear 5246 rotates, the first inner raceway 5223 is rotated by the rotation of the worm wheel 5245a. Thereby, the second inner raceway 5223a which is threaded over the first inner raceway 5223 moves forwards or backwards.

Moreover, the worm gear 5246 is provided on a gearshift shaft 5247. The opposite ends of the gearshift shaft 5247 are supported by a separate support means (not shown) . A motor (not shown) is connected to one of the opposite ends of the gear shift shaft 5247 which are supported by the separate support means.

Furthermore, the input unit 5300 is provided along the center axis of the housing 5100 to transmit external power to the speed change unit 5220.

Here, the input unit 5300 includes an input shaft 5310, a first end of which protrudes outside of the housing 5100. A second end of the input shaft 5310 is fastened to the tubular shaft 5314.

In addition, an output unit 5400 is coaxially provided at a position opposite the input unit 5300 to receive power transmitted from the input unit 5300 and output torque changed in speed by the speed change unit 5220.

The output unit 5400 comprises an output shaft 5410

which is coupled to the corresponding cover 5110. A first end of the output shaft 5410 extends outside of the housing 5100, and a second end thereof is disposed inside the housing 5100. Furthermore, a flange 5420 is provided on the second end of the output shaft 5410. The flange 5420 includes a plurality of power transmission arms 5422 which extends between the first and second outer raceways 5221 and 5221a and the first and outer inner raceways 5223 and 5223a. A contact member 5422a is provided on each of the power transmission arms 5422. The contact member 5422a is disposed between the adjacent rotary members 5226 and is in contact with the rollers 5226e of the corresponding rotary members 5226. The flange 5420 may be integrally provided on the output shaft 5410. Alternatively, the flange 5420 may be separately provided from the output shaft 5410. In this case, the flange 5420 is coupled to the output shaft 5410 using a coupling means (not shown) . Torque transmitted to the flange 5420 is output to the outside through the output shaft 5410.

As such, the contact members 5422a of the flange 5420 are disposed between the rotary members 5226 and thus guide the planetary motion of the rotary members 5226. Torque changed in speed by contact between the rotary members 5226 and the contact members 5422a is output

through the power transmission arms 5422 of the flange 5420 and the output shaft 5410.

The operation of the continuously variable transmission of the sixth embodiment having the above- mentioned construction is the same as that of the prior embodiments, therefore further explanation is deemed unnecessary.

[Seventh embodiment]

FIG. 18 is a sectional view illustrating a continuously variable transmission, according to a seventh embodiment of the present invention.

As shown in the drawing, the continuously variable transmission 1Of according to the seventh embodiment of the present invention includes a housing 6100 which has an internal space 6102 therein and is open on one end thereof. The open end of the housing 6100 is covered with a cover 6110.

Furthermore, a speed change unit 6200 is installed in the internal space 6102 of the housing 6100 to change speed of power transmitted from the outside.

In detail, the speed change unit 6200 includes an inner casing 6210 which has a space therein and is open on the opposite ends thereof. A cylindrical body 6212 is fastened to the circumferential inner surface of the inner casing 6210 using a retaining bar 6213.

In addition, bent parts 6212a which extend

predetermined lengths inwards are provided on the opposite ends of the cylindrical body 6212.

The speed change unit 6200 further includes first and second outer annular raceways 6221 and 6221a which include convex inner surfaces 6222 and 6222a having arc- shaped cross-sections . The first and second outer annular raceways 6221 and 6221a are fastened to the circumferential inner surface of the cylindrical body 6212 using a retaining bar 6212b. Furthermore, an elastic member 6323 is supported by one of the bent parts 6212a of the cylindrical body 6212. Preferably, the elastic member 6323 is disposed between the second outer raceway 6221a and the bent part 6212a which is disposed adjacent to a position at which torque changed in speed is output.

The speed change unit 6200 further includes first and second inner annular raceways 6223 and 6223a which respectively have outer diameters less than the inner diameters of the first and second outer raceways 6221 and 6221a. Convex surfaces 6224 and 6224a are respectively formed on the circumferential outer surfaces of the first and second inner raceways 6223 and 6223a.

As well, a support shaft 6314 is provided along the central axis of the cylindrical body 6212. A first end of the support shaft 6314 is fastened to the housing 6100. Furthermore, one of the first and second inner raceways

6223 and 6223a is integrally provided on a second end of the support shaft 6314, and a remaining one is threaded over the circumferential outer surface of the support shaft 6314. In this embodiment, the first inner raceway 6223 is threaded over the circumferential outer surface of the support shaft 6314, such that one end of the first inner raceway 6223 protrudes outside of the cylindrical body 6212. The second inner raceway 6223a is integrally provided at a position corresponding to the first inner raceway 6223 on the second end of the support shaft 6314 which is disposed inside the cylindrical body 6212.

Here, the second inner raceway 6223a may be fastened to the support shaft 6314 using a separate fastening means.

When the first and second outer raceways 6221 and 6221a and the first and second inner raceways 6223 and 6223a are installed in the inner casing 6210, they form a "+" shape. When one of the first and second inner raceways 6223 and 6223a, for example, in this embodiment, when the first inner raceway 6223 rotates, it threadedly moves on the support shaft 6314 towards or away from the second inner raceway 6223a.

Furthermore, a plurality of rotary members 6226 having high hardness and stiffness is installed between the first and second outer raceways 6221 and 6221a and the

first and second inner raceways 6223 and 6223a.

Each rotary member 6226 includes a cylindrical rotary member body 6226a. Contact surfaces 6226b having concave shapes are formed on the opposite ends of the rotary member body 6226a. A space 6226c is formed in the central portion of the rotary member body 6226a. A central shaft 6226d is provided in the space 6226c. A roller 6226e is provided around the central shaft 6226d.

Preferably, the diameter of the roller 622βe is greater than that of the rotary member body 6226a.

In addition, a speed control unit 6240 is provided around the first inner raceway 6223 of the speed change unit 6200. In detail, the speed control unit 6240 is provided around the circumferential outer surface of the outer end of the first inner raceway 6223 that protrudes outside of the inner casing 6210.

The speed control unit 6240 includes a worm wheel

6245a which is provided on the circumferential outer surface of the outer end of the first inner raceway 6223, and a worm gear 6246 which engages with the worm wheel

6245a. Thus, when the worm gear 6246 rotates, the first inner raceway 6223 is rotated by the rotation of the worm wheel 6245a. Thereby, the first inner raceway 6223 which is threaded over the support shaft 6314 moves forwards or backwards.

Moreover, the worm gear 6246 is provided on a

gearshift shaft 6247. The opposite ends of the gearshift shaft 6247 are supported by a separate support means (not shown) . A motor (not shown) is connected to one of the opposite ends of the gear shift shaft 6247 which are supported by the separate support means .

Meanwhile, an input unit 6300 which transmits external power to the speed change unit 6200 is provided in the internal space 6102 of the housing 6100.

The input unit 6300 includes a first gear 6302 which is circumferentially provided on the circumferential outer surface of the inner casing 6212, and a connection pipe 6306 which is disposed adjacent to the inner casing

6212. The connection pipe 6306 has a second gear 6304 which engages with the first gear 6302 and is oriented in the same direction as that of the first gear 6302.

Furthermore, a coupling hole 6306a is formed in one end of the connection pipe 6306. An input shaft 6310 is fitted into the coupling hole 6306a such that a portion of the input shaft 6310 protrudes outside of the housing 6100.

Hence, when external power is transmitted to the connection pipe 6306 through the input shaft 6310, the rotating force of the connection pipe 6306 is transmitted to the speed change unit 6200 via the first and second gears 6302 and 6304 which engage with each other.

In addition, an output unit 6400 receives external

power from the input unit 6300 and outputs torque changed in speed by the gearshift control unit 6200.

The output unit 6400 includes an output shaft 6410 which is coaxially provided with respect to the support shaft 6314 and coupled to the corresponding cover 6110. A first end of the output shaft 6410 extends outside of the housing 6100, and a second end thereof is disposed inside the housing 6100.

Furthermore, a flange 6420 is provided on the second end of the output shaft 6410. The flange 6420 includes a plurality of power transmission arms 6422 which extends between the first and second outer raceways 6221 and 6221a and the first and outer inner raceways 6223 and 6223a. A contact member 6422a is provided on each of the power transmission arms 6422. The contact member 6422a is disposed between the adjacent rotary members 6226 and is in contact with the rollers 6226e of the corresponding rotary members 6226.

The flange 6420 may be integrally provided on the output shaft 6410. Alternatively, the flange 6420 may be provided separately from the output shaft 6410. In this case, the flange 6420 is coupled to the output shaft 6410 using a coupling means (not shown) . Torque transmitted to the flange 6420 is output to the outside through the output shaft 6410.

The operation of the continuously variable

transmission of the seventh embodiment having the above- mentioned construction is the same as that of the prior embodiments, therefore further explanation is deemed unnecessary. Only, unlike the prior embodiments, in the seventh embodiment, the input unit 6300 is separately provided outside of the gearshift control unit 6200. External power applied to the input unit 6300 is transmitted to the gearshift control unit 6200 through the first and second gears 6302 and 6304.

As such, power transmitted from the input unit 6300 is changed in speed, and torque changed in speed is output to the outside through the flange 6420 and the output shaft 6410. Furthermore, in the continuously variable transmission 1Of, because the input unit 6300 having a predetermined transmission gear ratio is separately provided from the gearshift control unit 6200, a reduction gear ratio can be further increased. Moreover, as necessary, a speed ratio of the output to the input can be controlled by adjusting a gear ratio between the first and second gears 6302 and 6304. [Eighth embodiment] FIG. 19 is a sectional view illustrating a continuously variable transmission, according to an eighth embodiment of the present invention.

As shown in the drawing, the continuously variable transmission 1Og according to the eighth embodiment of the present invention includes a housing 7100 which has an internal space 7102 therein and is open on the opposite ends thereof. The open ends of the housing 7100 are covered with covers 7110.

Furthermore, a speed change unit 7200 is installed in the internal space 7102 of the housing 7100 to change the speed of power transmitted from the outside. In detail, the speed change unit 7200 includes an inner casing 7210 which has a space therein and is open on the opposite ends thereof. A cylindrical body 7212 is fastened to the circumferential inner surface of the inner casing 7210 using a retaining bar 7213. In addition, bent parts 7212a which extend predetermined lengths inwards are provided on the opposite two ends of the cylindrical body 7212.

The speed change unit 7200 further includes first and second outer annular raceways 7221 and 7221a which include convex inner surfaces 7222 and 7222a having arc- shaped cross-sections. The first and second outer annular raceways 7221 and 7221a are fastened to the circumferential inner surface of the cylindrical body 7212 using a retaining bar 7212b. Furthermore, an elastic member 7323 is supported by one of the bent parts 7212a of the cylindrical body 7212.

Preferably, the elastic member 7323 is disposed between the second outer raceway 7221a and the bent part 7212a which is disposed adjacent to a position at which torque changed in speed is output. The speed change unit 7200 further includes first and second inner annular raceways 7223 and 7223a which respectively have outer diameters less than the inner diameters of the first and second outer raceways 7221 and 7221a. Convex surfaces 7224 and 7224a are respectively formed on the circumferential outer surfaces of the first and second inner raceways 7223 and 7223a.

As well, a support shaft 7314 is provided along the central axis of the cylindrical body 7212. A first end of the support shaft 7314 is fastened to the housing 7100. Furthermore, one of the first and second inner raceways 7223 and 7223a is integrally provided on a second end of the support shaft 7314, and a remaining one is threaded over the circumferential outer surface of the support shaft 7314. In this embodiment, the first inner raceway 7223 is threaded over the circumferential outer surface of the support shaft 7314, such that one end of the first inner raceway 7223 protrudes outside of the cylindrical body 7212. The second inner raceway 7223a is integrally provided at a position corresponding to the first inner raceway 7223 on the second end of the support shaft 7314

which is disposed inside the cylindrical body 7212.

Here, the second inner raceway 7223a may be fastened to the support shaft 7314 using a separate fastening means. When the first and second outer raceways 7221 and

7221a and the first and second inner raceways 7223 and 7223a are installed in the inner casing 7210, they form a "+" shape. When one of the first and second inner raceways 7223 and 7223a, for example, in this embodiment, when the first inner raceway 7223 rotates, it threadedly moves on the support shaft 7314 towards or away from the second inner raceway 7223a.

Furthermore, a plurality of rotary members 7226 having high hardness and stiffness is installed between the first and second outer raceways 7221 and 7221a and the first and second inner raceways 7223 and 7223a.

Each rotary member 7227 includes a cylindrical rotary member body 7226a. Contact surfaces 7226b having concave shapes are formed on the opposite ends of the rotary member body 7226a. A space 7226c is formed in the central portion of the rotary member body 7226a. A central shaft 7226d is provided in the space 7226c. A roller 7226e is provided around the central shaft 7226d.

Preferably, the diameter of the roller 7226e is greater than that of the rotary member body 7226a.

In addition, a speed control unit 7240 is provided

around the first inner raceway 7223 of the speed change unit 7200. In detail, the speed control unit 7240 is provided around the circumferential outer surface of the outer end of the first inner raceway 7223 that protrudes outside of the inner casing 7210.

The speed control unit 7240 includes a worm wheel 7245a which is provided on the circumferential outer surface of the outer end of the first inner raceway 7223, and a worm gear 7246 which engages with the worm wheel 7245a. Thus, when the worm gear 7246 rotates, the first inner raceway 7223 is rotated by the rotation of the worm wheel 7245a. Thereby, the first inner raceway 7223 which is threaded over the support shaft 7314 moves forwards or backwards . Moreover, the worm gear 7246 is provided on a gearshift shaft 7247. The opposite ends of the gearshift shaft 7247 are supported by a separate support means (not shown) . A motor (not shown) is connected to one of the opposite ends of the gear shift shaft 7247 which are supported by the separate support means.

Furthermore, an electric motor 7300 which is selectively operated is installed in the housing 7100. The electric motor 7300 is fitted over the outer surface of the inner casing 7210 of the speed change unit 7200. In detail, the electric motor 7300 includes a stator 7302 which is fastened to the circumferential inner

surface of the housing 7100, and a rotor 7304 which is provided inside the stator 7302. The rotor 7304 has a cylindrical shape which is open on one end thereof, and is fastened, using bolts 7306, to a portion of the inner casing 7210 adjacent to a position at which torque is output. The electric motor 7300 is provided with a separate battery (not shown) for operating the rotor 7304.

As well, when the rotor 7304 is fastened to the inner casing 7210, a mounting member 7308 is further provided, which has therein a bearing to make the rotation of the rotor 7304 smooth. The mounting member 7308 is coupled to the rotor 7304 using the bolts 7306 such that the rotor 7304 can be supported by the mounting member 7308. Meanwhile, an output unit 7400 receives external power from the electric motor 7300 and outputs torque changed in speed by the gearshift control unit 7200.

The output unit 7400 includes an output shaft 7410 which is coaxially provided with respect to the support shaft 7314 and coupled to the corresponding cover 7110. A first end of the output shaft 7410 extends outside of the housing 7100, and a second end thereof is disposed inside the housing 7100.

Furthermore, a flange 7420 is provided on the second end of the output shaft 7410. The flange 7420 includes a plurality of power transmission arms 7422 which

extends between the first and second outer raceways 7221 and 7221a and the first and outer inner raceways 7223 and 7223a. A contact member 7422a is provided on each of the power transmission arms 7422. The contact member 7422a is disposed between the adjacent rotary members 7226 and is in contact with the rollers 722 βe of the corresponding rotary members 7226.

The flange 7420 may be integrally provided on the output shaft 7410. Alternatively, the flange 7420 may be separately provided from the output shaft 7410. In this case, the flange 7420 is coupled to the output shaft 7410 using a coupling means (not shown) . Torque transmitted to the flange 7420 is output to the outside through the output shaft 7410. The operation of the continuously variable transmission of the eighth embodiment having the above- mentioned construction is the same as that of the prior embodiments, therefore further explanation is deemed unnecessary. Only, unlike the prior embodiments, in the eighth embodiment, the electric motor 7300 generates power and transmits the power to the speed change unit 7200. Torque is changed in speed by the speed change unit 7200, and the torque changed in speed is output to the outside through the output shaft 7410.

The continuously variable transmission 1Og can

output low torque of low speed or high torque of high speed and thus is suitable for an energy saving motor. In the case of a conventional motor, the speed thereof cannot be optionally changed, so that a separate inverter is required to change the speed of the motor. However, because the inverter is an electric device, there are electric problems such as noise, distortion of harmony, etc. In addition, in the conventional art, typically, a frequency of 60hz is converted into another value, with the result that several problems are induced. However in the present invention, because a frequency of 60hz is directly used, and because the gearshift can be conducted by the continuously variable transmission 1Og, the conventional problems can be solved. Therefore, the reliability of the product is increased. As well, the present invention can be applied to a motor of high pressure and large capacity. Furthermore, the present invention can substitute for the conventional high pressure and large capacity inverter which is very expensive. A device which can conduct continuously variable transmission can be realized only by replacing the motor without requiring separate system construction work.

Although the preferred embodiments of the continuously variable transmission according to the present invention have been disclosed for illustrative

purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims .

[industrial Applicability]

As described above, the present invention provides a continuously variable transmission which can function as a clutch to control speed and has an integrated structure, so that it can be used in various fields, for example, in a machining device, a vehicle, etc.