[DESCRIPTION]

[Invention Title]

COUNTER ROTATING DRIVE MECHANISM

[Technical Field]

The present invention relates to a counter rotating drive mechanism for counter rotation of two shafts, and more particularly to a counter rotating drive mechanism having a structure for rotating two coaxial shafts in opposite directions via simple gear combination.

[Background Art]

A counter rotating drive mechanism enables a driven shaft arranged coaxially with a main shaft to rotate in an opposite direction to the main shaft when the main shaft is rotated by a driving source, and has recently been proposed for application to cooling fans, ventilation fans, blowers, manufacturing industries of ships or airplanes, etc. For example, a ship propulsion system, called a counter/contra rotating propeller (CRP), includes two propellers provided coaxially and rotating in opposite directions. Such a ship propulsion system uses a fluid-mechanical interaction between a front propeller and a back propeller so that rotational energy of water thrown away into sea can be recovered, thereby enhancing propulsion efficiency of a ship.

In a conventional CRP ship propulsion system, two shafts are rotatably fitted to form one double-shaft, and two motors rotate the double-shaft in opposite directions, so that two propellers connected to the double-shaft can rotate in opposite directions. However, the conventional CRP ship propulsion system has problems of high costs and bulky size due to installation of the two motors, as well as a complicated structure.

Accordingly, there has been proposed a device using a bevel gear to rotate

two shafts in opposite directions as disclosed in US Patent No. 5890938. In this device, two shafts, rotatably fitted with respect to each other, are formed with bevel teeth, so that a bevel gear engaging with the bevel teeth can rotate the two shafts in opposite directions.

[Disclosure]

[Technical Problem]

However, the conventional device has problems of a complicated structure, high manufacturing costs for components constituting main elements, and significant limitation to design of two counter rotating shafts. Accordingly, the present invention has been made in view of the above problems, and an aspect of the present invention is to provide a counter rotating drive mechanism of a compact structure enabling two coaxial shafts, i.e. a main shaft and a driven shaft, to rotate in opposite directions via simple combination of gears disposed between a pair of panels.

[Technical Solution]

In accordance with an aspect of the present invention, the above and other aspects can be accomplished by the provision of a counter rotating drive mechanism for rotating a main shaft and a driven shaft in opposite directions, the counter rotating drive mechanism including: first and second panels facing each other while rotatably supporting the main shaft and the driven shaft; a driving member disposed between the first and second panels and integrally formed with the main shaft; a transmission member connected to the driving member to transmit rotation of the driving member; a counter rotating member connected to the transmission member to reverse rotation of the transmission member; and a driven member connected to the counter rotating member to transmit rotation of the counter rotating member and integrally formed with the driven shaft, wherein the main shaft and the driven shaft are rotatably fitted to each other, and a connection part between the driving member and the transmission member and a connection part between the driven member and the

counter rotating member are provided with vibration preventing members to prevent the transmission member and the counter rotating member from vibrating in an axial direction.

The vibration preventing member may include flanges projecting from circumferences of the driving member and the driven member; and vibration preventing grooves formed in circumferences of the transmission member and the counter rotating member so that the flanges are inserted into the vibration preventing grooves.

According to another aspect of the present invention, a counter rotating drive mechanism for rotating a main shaft and a driven shaft in opposite directions includes: first and second panels facing each other while rotatably supporting the main shaft and the driven shaft; a driving member disposed between the first and second panels and integrally formed with the main shaft; a transmission member connected to the driving member to transmit rotation of the driving member; a counter rotating member connected to the transmission member to reverse rotation of the transmission member; and a driven member connected to the counter rotating member to transmit rotation of the counter rotating member and integrally formed with the driven shaft, wherein the main shaft and the driven shaft are coaxially provided and separated from each other, and a connection part between the driving member and the transmission member and a connection part between the driven member and the counter rotating member are provided with vibration preventing members to prevent the transmission member and the counter rotating member from vibration in an axial direction.

The vibration preventing member may include flanges projecting from circumferences of the driving member and the driven member; and vibration preventing grooves formed in circumferences of the transmission member and the counter rotating member so that the flanges are inserted into the vibration preventing grooves.

According to a further aspect of the present invention, a counter rotating drive mechanism for rotating a main shaft and a driven shaft in opposite directions includes: first and second panels facing each other while rotatably supporting the

main shaft and the driven shaft; a driving member disposed between the first and second panels and integrally formed with the main shaft; a transmission member connected to the driving member to transmit rotation of the driving member; a counter rotating member connected to the transmission member to reverse rotation of the transmission member; and a driven member connected to the counter rotating member to transmit rotation of the counter rotating member and integrally formed with the driven shaft, wherein the main shaft and the driven shaft are rotatably fitted to each other, each of the transmission member and the counter rotating member has a spacing projection formed thereon, and an outer rim of the spacing projection has an auxiliary flange proj ected outward.

The auxiliary flange may be inserted into a vibration preventing groove formed in circumferences of the transmission member and the counter rotating member to prevent the transmission member and the counter rotating member from vibrating in an axial direction. According to yet another aspect of the present invention, a counter rotating drive mechanism for rotating a main shaft and a driven shaft in opposite directions includes: first and second panels facing each other while rotatably supporting the main shaft and the driven shaft; a driving member disposed between the first and second panels and integrally formed with the main shaft; a transmission member connected to the driving member to transmit rotation of the driving member; a counter rotating member connected to the transmission member to reverse rotation of the transmission member; and a driven member connected to the counter rotating member to transmit rotation of the counter rotating member and integrally formed with the driven shaft, wherein the main shaft and the driven shaft are coaxially provided and separated from each other, each of the transmission member and the counter rotating member has a spacing projection formed thereon, and an outer rim of the spacing projection has an auxiliary flange projected therefrom.

The auxiliary flange may be inserted into a vibration preventing groove formed in circumferences of the transmission member and the counter rotating member to prevent the transmission member and the counter rotating member from vibrating in an axial direction.

The driving member, the transmission member, the counter rotating member and the driven member may include gears or general friction rollers.

The driving member may circumscribe the transmission member, and the driven member may inscribe the counter rotating member. The driving member may inscribe the transmission member, and the driven member may circumscribe the counter rotating member.

[Advantageous Effects]

As described above, a counter rotating drive mechanism according to an embodiment of the present invention enables two coaxial shafts to rotate in opposite directions via simple and compact gear combination, so that it can be highly useful for various propulsion systems or the like.

Further, only simple gears such as spur gears, axes of which are parallel, are used to drive two shafts to rotate in opposite directions, reducing costs of manufacturing and installing the counter rotating drive mechanism. Also, a vibration preventing member is provided for preventing a transmission member and a counter rotating member from vibrating in an axial direction, so that malfunction can be prevented, thereby enhancing reliability.

In addition, each of the transmission member and the counter rotating member is provided with a spacing projection at one side thereof, so that each shaft can be shortened to reduce bending moment or twisting moment applied to the shaft, improving total durability.

[Description of Drawings]

Fig. 1 is an exploded perspective view of a counter rotating drive mechanism according to an embodiment of the present invention. Fig. 2 is an assembled perspective view of the counter rotating drive mechanism according to the embodiment of the present invention.

Fig. 3 is a plan view of the counter rotating drive mechanism according to

the embodiment of the present invention, in which a driving member and a transmission member are shown.

Fig. 4 is a sectional view taken along line A-A of Fig. 2.

Fig. 5 is an exploded perspective view of the counter rotating drive mechanism according to the embodiment of the present invention, in which an auxiliary flange is shown.

Fig. 6 is an assembled sectional view of Fig. 5.

Fig. 7 is a sectional view of the counter rotating drive mechanism according to the embodiment of the present invention, in which a main shaft and a driven shaft are separately provided.

Fig. 8 is a plan view of a counter rotating drive mechanism according to another embodiment of the present invention.

[Best Mode]

Below, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

Further, the following embodiments do not limit the scope of the present invention but are exemplarily. Herein, like elements refer to like numerals or names throughout.

Fig. 1 is an exploded perspective view of a counter rotating drive mechanism according to an embodiment of the present invention; Fig. 2 is an assembled perspective view of the counter rotating drive mechanism according to the embodiment of the present invention; Fig. 3 is a plan view of the counter rotating drive mechanism according to the embodiment of the present invention, in which a driving member and a transmission member are shown; Fig. 4 is a sectional view taken along line A-A of Fig. 2; Fig. 5 is an exploded perspective view of the counter rotating drive mechanism according to the embodiment of the present invention, in which an auxiliary flange is shown; Fig. 6 is an assembled sectional view of Fig. 5; and Fig. 7 is a sectional view of the counter rotating drive mechanism according to the embodiment of the present invention, in which a main shaft and a driven shaft are

separately provided.

The counter rotating drive mechanism 100 according to the embodiment of the present invention enables a main shaft 112 and a driven shaft 114 to rotate in opposite directions. The counter rotating drive mechanism 100 includes first and second panels 120, 122 facing each other while rotatably supporting the main shaft 112 and the driven shaft 114; a driving member 130 disposed between the first and second panels 120 and 122 and integrally formed with the main shaft 112; a transmission member 140 engaging with the driving member 130 to transmit rotation of the driving member 130; a counter rotating member 150 engaging with the transmission member 140 to reverse rotation of the transmission member 140; and a driven member 160 engaging with the counter rotating member 150 to transmit rotation of the counter rotating member 150 and integrally formed with the driven shaft 114.

The main shaft 112 and the driven shaft 114 are coaxially and rotatably fitted to each other. For this purpose, the driven shaft 114 has a hollow shape so that the main shaft 112 can be rotatably fitted into the driven shaft 114.

Further, each of the first and second panels 120 and 122 has a circular shape and is formed with a center hole 124 to which the main shaft 112 and the driven shaft

114 are rotatably coupled while passing therethrough, and a shaft hole 126 to which shafts 142 and 152 of the transmission member 140 and the counter rotating member

50 are rotatably coupled.

The driving member 130, the transmission member 140, the counter rotating member 150, and the driven member 160 may be realized by a gear, a general friction roller or other various power transmission elements. In the case of the gear, various gears such as a spur gear, a helical gear, a double-helical gear, or the like can be used, and a gear ratio may be 1 : 1 or greater.

Herein, the gears are used as the driving member 130, the transmission member 140, the counter rotating member 150, and the driven member 160 as shown in the accompanying drawings. In this embodiment, the mechanism includes three transmission members

130 and three counter rotating members 150. The driving member 130, the

transmission members 140, the counter rotating members 150, and the driven member 160 partially engage with each other in this sequence between the first and second panels 120 and 122. The number of transmission members 130 is equal to the number of counter rotating members 150, and each of the transmission member 130 and the counter rotating member 150 may be provided in plural.

Further, vibration preventing members 170 are provided to a connection part between the driving member 130 and the transmission member 140, and to a connection part between the driven member 160 and the counter rotating member

150, preventing the transmission member 140 and the counter rotating member 150 from vibrating in an axial direction.

The vibration preventing members 170 include flanges 172 projecting from circumferences of the driving member 130 and the driven member 160, and vibration preventing grooves 174 formed in circumferences of the transmission member 140 and the counter rotating member 150 so that the flanges 172 are inserted into the vibration preventing grooves 174.

In detail, the flanges 172 are provided as two stages at top and bottom sides of the driving member 130 and at top and bottom sides of the driven member 160, as shown in Fig. 1.

The flanges 172 may be provided to the bottom side of the driving member 130 and the top side of the driven member 160, and be inserted into the vibration preventing grooves 174 of the transmission members 140 and the counter rotating members 150.

Here, the height of the flange 172 may be equal to the height of gear teeth formed on the circumferences of the driving member 130 and the driven member 160, or may be higher or lower than the gear teeth of the driving member 130 and the driven member 160.

Further, spacing projections 180 are projected from the bottom sides of the transmission members 140 and the top sides of the counter rotating members 150.

As shown in Fig. 5 or 6, auxiliary flanges 190 may protrude from outer rims of the spacing projections 180 formed at the bottom side of the transmission member 140 and at the top side of the counter rotating member 150.

The auxiliary flange 190 of the transmission member 140 is inserted into the vibration preventing groove 174 of the counter rotating member 150, and the auxiliary flange 190 of the counter rotating member 150 is inserted into the vibration preventing groove 174 of the transmission member 140, thereby preventing the transmission members 140 and the counter rotating members 150 from vibrating in the axial direction.

Here, the flange 172 of the vibration preventing member 170 may be used independent of the auxiliary flange 190.

As shown in Fig. 7, the main shaft 112 and the driven shaft 114 may be coaxially provided and separated from each other. In this case, the main shaft 112 and the driven shaft 114 may be separately used.

In Figs. 1 to 7, the driving member 130 circumscribes the transmission member 140, while the driven member 160 circumscribes the counter rotating member 150, thereby transmitting power. Meanwhile, as shown in Fig. 8, according to another embodiment of the present invention, the driving member 130 may inscribe the transmission member 140. In this embodiment, reference numerals indicate like elements of the above embodiment.

Although not shown in the drawings, the counter rotating member 150 may inscribe the driven member 160.

Also, the driving member 130 may inscribe the transmission member 140, while the driven member 160 may inscribe the counter rotating member 150.

Operation and effects of the counter rotating drive mechanism according to an embodiment of the present invention will be described hereinafter. The driving member 130, the driven member 160, the transmission members

140, and the counter rotating members 150 are disposed between the first and second panels 120 and 122, in which three transmission members 140 are provided around the driving member 130 and partially engage with one another. Further, each of the counter rotating members 150 is disposed between the transmission members 140, so that the transmission members 140 partially engage with the counter rotating members 150. The counter rotating members 150 partially engage with the driven

member 160, so that the main shaft 112 and the driven shaft 114 can rotate in opposite directions.

In more detail, as shown in Fig. 3, the main shaft 112 and the driving member 130 rotate in the clockwise direction, and the transmission member 140 gearing with the driving member 130 transmits power from the main shaft 112 while rotating in the counterclockwise direction.

Then, the counter rotating members 150 partially gearing with the transmission members 140 rotate in the clockwise direction depending on the rotation of the transmission members 140. The driven member 160 partially gearing with the counter rotating member 150 rotates in the counterclockwise direction depending on the rotation of the counter rotating members 150, so that the driven shaft 114 integrally formed with the driven member 160 can rotate in the counterclockwise direction, i.e., in the opposite direction to the rotation of the main shaft 112. At this time, the flanges 172 protruding from the top and bottom circumferences of the driving member 130 and from the top and bottom circumferences of the driven member 160 are inserted into the vibration preventing grooves 174 formed on the middle circumferences of the transmission members 140 and the counter rotating members 150, so that the transmission members 140 and the counter rotating members 150 are prevented from vibrating in the axial direction, thereby preventing malfunction during operation of the mechanism while enhancing reliability thereof.

Also, the spacing projections 180 are formed at one side of the transmission member 140 and the counter rotating member 150, so that the engagement between the respective members 130, 140, 150 and 150 can be precisely secured. Further, the shafts 142 and 152 are so short that the twisting moment or the bending moment applied to the shafts 142 and 152 can be reduced, thereby improving durability of the counter rotating drive mechanism 100.

As shown in Fig. 7, the main shaft 112 and the driven shaft 114 are separated from each other. Thus, additional brackets (not shown) may be attached to the main shaft 112 and the driven shaft 114 so as to be rotated in opposite directions, so that

they can be used for athletic equipment.

Meanwhile, according to another embodiment of the present invention shown in Fig. 8, a driving member 130' and a driven member (not shown) have inward gear teeth, so that the gear teeth of the transmission member 140 inscribe the gear teeth of the driving member 130' and the gear teeth of the counter rotating members 150 inscribe the gear teeth of the driven member.

As described above, the counter rotating drive mechanism according to the present invention enables a main shaft and a driven shaft to rotate in opposite directions via simple combination of a driving member, transmission members, counter rotating members, and a driven member. Further, the transmission members and the counter rotating members are integrally formed and rotatably supported between the first and second panels, so that the length of the shafts can be shortened, thereby allowing the counter rotating drive mechanism to have a compact structure. Also, twisting moment or bending moment applied to the shafts is reduced, thereby improving durability of the counter rotating drive mechanism.

Moreover, the counter rotating drive mechanism uses an inexpensive and simple gear structure such as a spur gear structure, axes of which are parallel. Thus, there is no need to use an expensive gear structure such as the conventional bevel gear structure.

In the counter rotating drive mechanism, a driving means such as a motor is connected to an input end of the main shaft, and each output end of the main shaft and the driven shaft is provided with a pair of propellers such that the propellers can be rotated in opposite directions, thereby enhancing propulsion efficiency in fluids such as gases and liquids.

When the counter rotating drive mechanism is applied to a ventilation fan and a blower, the propeller may be easily replaced by a fan.

Further, the main shaft and the driven shaft are separately provided and mounted to rotate in opposite directions, so that the counter rotating drive mechanism can be employed in athletic equipment having a pedal, or the like.

Although not specifically described herein, the gear ratio of the gears

engaging with each other may be varied to change the rotating directions and rotation speeds of the main shaft and the driven shaft.

Although the exemplary embodiments of the present invention have been disclosed with reference to the accompanying drawings for illustrative purposes, it should be understood that the present invention is not limited to these embodiments, and that various modifications, additions and substitutions can be made without departing from the scope and spirit of the present invention as disclosed in the accompanying claims.