BACKGROUND OF THE INVENTION This invention relates to a unique transmission which is able to transmit higher torque levels than prior art transmissions. Moreover, this invention extends to a combined transmission system that transmits an oscillating input into a single direction output. Moreover, inventive methods for starting a vehicle and braking a vehicle utilizing the inventive systems are disclosed in this application. Transmissions are utilized to transmit rotation for a variety of purposes. The term "transmission" as utilized in this application, is not as narrow as a vehicle transmission, although it would extend to such transmissions. Rather, this invention extends to any system wherein a source of movement is transmitted through a driving member to move a driven member. Prior ar transmissions have not successfully transmitted high torque levels.

One common type of transmission is a one-way clutch. In these known systems, rollers, or other drive members are engaged within notches or openings in a driven member. The rollers engage and move the driven member when rotation is transmitted is a first direction, but will slip when rotation is transmitted in a second direction. These types of clutches have enjoyed wide usage, but have been unable to transmit high torque loads. One proposal suggests using a pair of such clutches with an oscillating input to perform as a vehicle transmission. Due to the low torque load, this system would be impractical.

In one system disclosed in a Russian inventor certificate granted to the inventor of this invention, a self-locking transmission is utilized to transmit rotation. In the disclosed system, a worm and worm gear combination are utilized to transmit

rotation. The rotation is transmitted utilizing the engaged teeth and thread of the gears such that there is no relative movement between the two gear members during this rotation. With such a system, many valuable benefits result. In particular, one is able to accurately and efficiently transmit rotation through the self-locking transmission.

In addition, the standard power supply utilized with such systems has difficulty allowing any of the structure to freely turn about 360 degrees. Instead, electrical supply lines have typically limited the operative members to a restricted range of rotation. This is, of course, undesirable. The term "self-locking" as is utilized in this application to describe the inventive worm and worm gear combination, requires that the teeth of the worm gear when in contact with the thread of the worm, are capable of rotating the worm about the axis of the worm gear. The teeth do not slip on the thread causing the thread to rotate about its own axis. By carefully selecting the material of the respective teeth and threads, and the respective angles, a worker of ordinary skill in the art would be able to achieve this goal.

There are some deficiencies in the system disclosed in the prior inventor's certificate, however, and this invention and a related co-pending application of the same inventor, serial no. 08/353,797, and PCT International Application No. PCT/US95/ 15938, disclose improvements to the prior art system.

SUMMARY OF THE INVENTION

In one feature of the present invention, a worm and worm gear combination utilized to transmit rotation have a smaller ratio of worm gear teeth to worm threads. In the past, it has been believed that at least 18 teeth are required for a worm gear to be used with a worm combination. This has typically been required since the standard worm and worm gear combination utilizes the threads and teeth rotation to drive the driven member.

The inventive system utilizes the engaged teeth and thread of the two gear members to drive the driven member. Typically, the driven member is driven about an axis other than its axis of rotation. As such, the teeth are not performing their ordinary function, but rather are providing abutting surfaces. Moreover, as disclosed in more detail in the above cited co-pending applications, it is often desirable to allow the driving members to return to an initial position after the driving stroke. In such a system, a second motor may be placed for rotating one of the gear members relative to the other to allow a return to an original position without any further transmission of motion. In a worm and worm gear combination having a high tooth to thread ratio, the motor would have to turn the worm at an undesirably high rate of rotation to achieve the return movement. In addition, in a system disclosed in this application, it is sometimes desirable to rotate the worm relative to the worm gear without any interaction between the teeth and threads. Again, if the worm and worm gear combination had a high tooth to thread ratio, the motor would have to turn at an undesirably high rate. To this end, in one aspect of this invention, a self-locking worm/worm gear combination has a worm gear to

worm thread ratio that is preferably less than 10. In one most preferred embodiment, it is preferably three, or even two.

More preferably, the worm and worm gear combination is incorporated into a system wherein the worm is mounted for rotation in a rotor. The rotor surrounds a driving worm gear. A rotational input is applied to the worm gear. The worm gear teeth engage the thread on the worm, the worm and the rotor rotate about the axis of the worm gear. This rotation is without relative movement between the engaged teeth of the worm and worm gear. The rotor movement is utilized as work. An auxiliary motor is preferably mounted on the rotor, and rotates the worm relative to the worm gear to either return the worm gear to its original position, or allow the worm gear to move relative to the worm when an oscillating input is utilized. When subjected to an oscillating input, the worm and rotor act as a mechanical diode, resulting in a single direction output. The motor may include electrical components associated with the rotor, and the worm may include a conductive material such that it can be rotated as a magnet. Alternatively, a separate drive motor may be mounted on the motor and associated with the worm.

In further features, counterbalances may be applied to the worm and to the rotor to insure that the rotation of the tube is smooth and desirable. In another feature, a rotating electrical supply may be associated with the input shaft to deliver electrical power to the secondary motors for driving the worm. Due to this, there is no problem connecting the electrical connections to the operative members, even when the operative members freely rotate about 360 degrees.

In further aspects of this invention, two of the worms, and worm gears and rotor combinations are mounted in combination. An oscillating input is applied to the two worm gears. One of the worms is driven by one sign or direction of the oscillating input, while the second of the worms is rotated relative to its worm gear to avoid any rotation during this first direction. The rotor associated with the driven worm is thus driven to rotate above the axis of the worm gear. When the second rotation direction is applied to the input shaft, the first worm, which was originally driven, is now rotated about its axis such that it is no longer driven by the first worm gear. The first worm gear thus rotates relative to the first worm during this rotation direction. At that time, the second worm is driven by the second worm gear. A mechanical connection preferably connects the two worm and worm gear sets such that the rotation of both associated rotors results in a single directional rotation on an output shaft.

With such a system, the above-described features of each worm and worm gear combination become particularly important. An auxiliary motor must drive each worm during one half of the operation to allow the worm gear to rotate relative to the worm without any interaction. For such a result to occur, the worm effectively has to rotate at a rate which is equal to the ratio of the gear teeth and thread of the worm gear and worm. As mentioned above, with this invention a ratio of three or less is preferred. Thus the worm gear must be driven by the auxiliary motor at a speed which is three times the input speed to the worm gear. In the prior art worm and worm gear systems which have had a number of teeth on the order of 18, the necessary rotational speed to the worm would be impractically high.

In further features of this invention, the system provided by the two worm

and worm gear sets described above can be utilized as a part of a vehicle transmission with an oscillating transmission. When this system is utilized as part of a vehicle transmission with an oscillating transmission, a method of starting a vehicle includes the steps of rotating both of the worms with an auxiliary motor when starting the vehicle. This reduces the load on the vehicle engine during starting as no torque will be transmitted. Instead, both of the worms will be rolling along the worm gears during both of the oscillating input directions. No rotation will be transmitted to the output shaft until the motor has started up sufficiently such that the torque may be engaged. At that time, the method described above will begin.

In a method of braking a vehicle utilizing such a transmission, when an indication is made that it is desirable to reduce the speed of the vehicle, the input speed to the worm gears is reduced. At the same time, the auxiliary motors driving the worms are also actuated to cause the worms to rotate opposite to the normal driving orientation. Positive torque will not be transmitted to the worms, and thus to the rotors. Instead, the worms are controlled such that they utilize rotation that is opposed to the typical driving direction. Thus, the worms are driven by their respective auxiliary motors, not at positive torque, but rather to add negative torque to the output shaft. This method will assist in the rapid braking of the vehicle speed.

These and other features of the present invention may be best understood from the following specification and drawings, of which the following is a brief description.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a cross-sectional view of a worm and worm gear combination incorporating the present invention.

Figure 2 is a cross-sectional view through the system of Figure 1 along a different plane. Figure 3 shows one feature of the present invention.

Figure 4 shows a worm incorporated into the present invention.

Figure 5 is an end view of the gear shown in Figure 4.

Figure 6 shows a further detail of one embodiment of the inventive system.

Figure 7 shows an end view of the embodiment shown in Figure 6. Figure 8 shows one embodiment of a clutch incorporated into the present invention.

Figure 9 shows an alternative clutch.

Figure 10 shows a first embodiment for transmitting an oscillating input into a single directional rotation. Figure 11 shows a second embodiment transmission.

Figure 12 shows a third embodiment transmission.

Figure 13 shows another arrangement of the inventive system for transmitting particularly high torque loads.

Figure 14 schematically shows some of the functions of the inventive

transmission.

Figure 15 shows an application of the inventive system.

Figure 16 shows another application of the inventive system.

Figure 17 shows yet another application of the inventive system.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A worm and worm gear combination is illustrated in Figure 1. As shown, an enveloping worm gear 1 engages an enveloping worm 2. An auxiliary motor 3 is associated with the worm gear through a clutch 7 to drive the worm under certain conditions. Clutch 7 as shown in this figure may be an electromagnetic clutch which is associated with the transmission between motor 3 and worm 2. As shown, worm 2 is journaled in bearings in rotor 8. An output shaft 9 is shown centered on the rotational axis of the worm gear 1, but as will be shown below, is independent of the worm gear 1. As is further shown, a counterweight 36 may be inserted into the rotor 8 where appropriate. As shown in Figure 2, an input shaft 4 drives worm gear 1. Output shaft 9 rotates with rotor 8. A fixed or primary coil 6 is mounted to a fixed housing 28, and associated with a moving coil 5 to transmit electrical energy to the motor 3. The connection is shown schematically, however, the coils are of a known type wherein electrical power is supplied to the fixed coil 6, and

transmits electrical power to the moving coil 5. As an alternative to the rotating coil 5 and fixed coil 6, a brush commutator connection could be utilized. Again, such structure is known in the electrical arts, but has not been utilized for the inventive purpose described in this application. During operation of the system shown in this figure, rotor 8 rotates relative to the primary fixed coil 6. Moving coil 5 rotates with the rotor 8. The primary coil 6 can transmit power to the coil 5 at any relative location, and thus there will be no interruption in power between the coil 6 and the motor 3 or the clutch 7.

As shown in Figure 3, the worm 2 has a single thread in a preferred embodiment. The worm gear 1 has three teeth spaced about the circumference of

the worm gear 1. As shown, a gap G exists between any tooth on worm gear 1 and

the thread on worm 2. With the gears 1 and 2 in the position shown in Figure 3, further rotation of the worm gear 1 about its axis causes the worm 2 to rotate about the axis of worm gear 1. Rotor 8 moves along with worm 2 during this rotation.

In this way, rotation of the output shaft 9 is achieved. This rotation is without relative movement between the gears 1 and 2. That is, the teeth of the worm gear

1 directly engage the thread on the worm 2, and there is no relative movement during this transmission. This rotation is provided by a normal force from the worm gear teeth against the thread on the worm. There is no relative movement, and thus the efficiency is maximum. This rotation is achieved if the teeth and threads are designed to be "self-locking" as described above. A worker of ordinary skill in the art would recognize how to design a self-locking gear set.

Although various combinations of this basis system are within the scope of this invention, one main feature of this invention is for utilizing such combinations as a pair and transmitting an oscillating input into a single direction output. For such cases, the input to the worm gear 1 switches between two directions. It is only desirable to have that input rotate the worm 2, and hence rotor 8, during one half of the oscillating input. When it is not desirable to have the worm gear 1 rotating the worm 2, the system rotates worm 2 through motor 3. This rotation is provided such that the thread on the worm 2 avoids any forces from the teeth on worm gear 1, thus avoiding any transmission of rotation to the worm 2, and rotor 8. This benefit will be explained in more detail below. As explained in more detail in the above-referenced co-pending U.S. applications, it is also desirable to have some gap between the teeth on the worm gear 1 and the worm 2. Gap G is taken up prior to any transmission of rotation, and it is desirable that the contact be initially taken up

at a low torque load. These features are explained in more detail in the above-referenced co-pending application.

Moreover, since it is desirable to rotate the worm to avoid the worm gear

1 teeth, it is desirable to increase the size of the gap G to reduce the required rotational speed motor 3 must impart to worm 2. As an example, worm 2 as shown in Figure 3 must be rotated by motor 3 at a speed which is three times the input speed to the worm gear 1 : This is equal to the ratio of gear teeth on worm gear 1 to the threads on worm 2. As shown in this figure, the ratio is 3 to 1. It is typically assumed that the ratio need be at least 18 for an effective worm and worm gear combination. Such a ratio would require an auxiliary motor 3 turning the worm 2 to avoid interaction with the teeth on worm gear 1 that would be impractical when the input speed is very high. In the present invention, it is preferred that the ratio of teeth on the worm gear 1 relative to the threads on worm 2 is less than 10 to 1. Most preferably, the ratio is three as shown, or even less. It is possible that only 2 teeth need be utilized on the worm gear 1. The teeth could actually be more akin to stops than standard gear teeth. As explained above, the transmission of power from the worm gear 1 to the worm 2 occurs without relative movement as is typically the case with the worm and worm gear combination. Rather, the teeth of the worm gear 1 are brought into contact with the thread on the worm 2, and the worm gear 2 is prevented from rotation about its own axis. A force is applied to the worm gear 1 which drives the worm 2 about the axis of the worm gear 1 , thus imparting rotation to the rotor 8.

Since the worm and worm gears are not utilized as in standard gears to have inter-engaging teeth and threads, the material selected for the members is different

than that which has been utilized in the past. In the past, the worm and worm gears have been formed of materials having low coefficients of friction and a lubricant is typically utilized. In this invention, no lubricant would be desirable typically. Moreover, the worm and worm wheel are made from a strong material such as steel. The shape of the teeth and threads and the worm and worm gears are preferably as shown in the drawings. Even so, a worker of ordinary skill in the art would recognize that other shapes would come within the scope of this invention. In addition, a material that actually increases the friction may be placed on the teeth and threads. Again, it is a goal to achieve the self-locking property, rather than any smooth movement between the worm and worm gear. The reduction of the number of teeth on the worm gear also reduce the inertia of the worm gear, thus increasing the speed at which the worm gear can shift between its oscillating inputs. Finally, rather than simply reducing the number of worm gear teeth, the thickness of the worm thread could be reduced to result in an acceptable gap. As shown in Figure 4, it may be desirable to include counterweights 10 and

11 at the end of the worm 2. The counterweights may be formed by cutouts or holes in the worm 2. Figure 5 shows further details of the counterweight 10 at one end of worm 2.

As shown in Figures 6 and 7, as an alternative to the separate motor 3, a stator 12 and a core 13 may be incorporated into the rotor 8. With such a system, the worm 2 is preferably made of a conductive material. By controlling the electrical energy to the motor 12 and 13, the system can provide rotation of the worm 2 to replace the auxiliary motor 3 as described above. The preferred motor

is an asynchronous motor having a relatively low torque.

With either the separate motor 3, or the motor 12 and 13 as shown in

Figures 6 and 7, the auxiliary motor will be of a relatively low torque. The motor's function is to turn the worm without any interaction relative to the teeth of the worm gear. Thus, a high torque motor need not be utilized. For that reason, only a low power load is required to operate the auxiliary motor.

Figures 8 and 9 show alternative clutches to replace the electromagnetic clutch 7 as shown in Figures 1 and 2. In one clutch 7a shown in Figure 8, a pair of disks 14 and 15 are held into contact by a spring 16. As shown in Figure 9, a clutch 7b can incorporate a strong spring 17 connecting a motor shaft 3 to the worm 2. With either clutch, should the resistance to rotation on the worm 2 exceed the force of the springs, the members will be allowed to slip relative to each other.

Figure 10 shows a transmission 19 which may be utilized to take an oscillating input on shaft 4 and transmit the oscillating input into a single directional rotation on shaft 9. Such a system is desirable in that each of the worm and worm gear combinations described above can transmit very high torque loads when compared to prior art transmissions.

Thus, in a typical vehicle application, the normal output of the engine is passed through a mechanical transformer that would transform the single directional output into an oscillating output. The transformers may be of known construction. The oscillating output is then communicated to the input shaft 4. As shown in Figure 10, the worm and worm gear combination 1 and 2 is provided with a second worm and worm gear combination 18 and 19. A second auxiliary motor 20 and clutch 21 are also included as is a second rotor 22. Electrical connections 6 and 5 are associated with both of the worm and worm gear sets. The worm and worm

gear subset 1 and 2 is driven by the input 4 as described above during one half of the oscillating cycle on the input 4. As shown, a gear 23 rotates with a rotor 22 and engages another gear 24. Gear 24 drives a gear 25 which in turn drives an idler gear 26. Idler gear 26 drives a gear 27 which is associated with the output shaft 9. Now, the operation will be described during one cycle of an oscillating input when applied to the input shaft 4. During a first direction of movement, the worm gear 1 drives the worm 2, to in turn drive its rotor 8 and apply a rotation to output shaft 9. At that time, the auxiliary motor 20 rotates worm 19 such that its thread avoids the teeth on the worm gear 18. Again, the ratio of the worm gear teeth to the threads on the worm is preferably selected to be low such that the auxiliary motor 20 need not rotate at a very high rate of speed. Once that direction of oscillating input has ended, and the other direction begins, motor 20 is stopped. Rotation is next transmitted from the worm gear 19 to the worm 19. At the same time, the auxiliary motor 3 is actuated to roll the teeth of worm 2 relative to the teeth on worm gear 1 , avoiding any interaction. The rotation of the worm 19 causes corresponding rotation of rotor 20, and rotation through gear 23 to gear 24 and gear 25. Gear 25 in turn drives idler gear 26, which drives gear 27 thus applying rotation to shaft 9. In this way, the oscillating input 2 to input shaft 4 is transmitted into a single directional rotational force on output shaft 9. The two worm and worm gear combinations, each individually transmit a high torque. The overall system 19 is thus able to transmit a very high torque load.

The inventive systems shown in Figure 10-12 also allow the starting and braking of a vehicle incorporating this system as its transmission. In operating the system to start a vehicle, both auxiliary motors 3 and 20 are rotated to avoid any

96/31714 PCMJS96/02918

-14- interaction between their respective worms and the worm wheels. In this way, there is no torque load transmitted to the input shaft 4. Rather, the input shaft 4 may build up to its operating speed without having to overcome any torque load. Once a required period of time has expired, or once a torque meter recognizes that the input shaft 4 is now capable of transmitting torque, one of the auxiliary motors 3 and 20 is stopped such that torque will then be transmitted to its respective worm

2 or 19.

In a method of braking a vehicle, the torque to the input shaft 4 is reduced upon receipt of a signal that it is desirable to brake the vehicle. At that time, the normal operation of the auxiliary motors 3 and 20 is switched. The auxiliary motor that would typically be driven to avoid any driving interaction between its worm and respective worm gear during a particular direction of rotation of the oscillating input is switched such that it does achieve such a connection. The worm that would typically be providing the driving connection in that first direction is switched such that it avoids any connection. In this way, there is no positive torque delivered to the output shaft. Instead, there is a negative torque delivered to slow the rotational speed of the output shaft 9.

Figure 11 shows an alternative embodiment wherein the connection between the two worm and worm gear combinations is replaced by a bevel gears 29, 30 and 31 to drive output shaft 9 when worm 19 is driving rotor 22. Other than this aspect, the operation of the system proceeds as with the earlier embodiment.

As shown in Figure 12, a planetary gear transmission can replace the transmission shown in Figures 10 and 11. In the planetary transmission, a cage 35 rotates with the rotor 8. A sun gear 33 is mounted on the input shaft 4. A central

gear 32 rotates about input shaft 4, and is driven to rotate with the rotor 22. Thus, when worm 18 rotates about the axis of worm gear 19, the gear 32 is also rotated.

A double satellite 34 rotates about gears 32 and 33, and rotates cage 35. The operation of the system proceeds as with the above-described systems, and results in a single directional output at output shaft 9.

Figure 13 shows a further refinement of the basic worm and worm gear system for transmitting particularly high torque loads. In this system, each worm gear 1 is provided with two worms 2 and 36. The worms are each provided with clutches 7 and 38, and auxiliary motors 3 and 37. The operation of the auxiliary worm 36 is identical to that of worm 2 during the entire operation of this system. Such a dual worm system is able to transmit a higher torque load than the single worm system. Two of these systems can be incorporated into a transmission such as shown in Figures 10-12, or may be utilized as a single set.

The system is actually a bit simplified in its description to this point. In fact, a control for the combined systems must accurately turn the auxiliary motors at a rate such that the worm avoids interaction with the worm gear teeth. In the systems disclosed in Figures 10-12, both rotors will be rotating in the same direction at all times. This is due to the mechanical connection. Thus, with reference to Figures 10 and 14 as an example, when the worm 19 is not being utilized to actually transmit torque to the rotor 22, but rather the worm 2 is transmitting the torque to the rotor 8, the worm 19 must avoid contact with the worm gear 18. The worm 19 will be rotating at the rotational speed of the rotor 22, and in this case, the worm gear 18 will be rotating in an opposed direction. Thus, as shown schematically in Figure 14a, the rotation S _g from the worm wheel 1 is in an opposed direction to the

rotation of the rotor , which is, of course, applied to the worm 2. This would be the rotation during the normal operation of the system showing Figure 10-12, when the other combination is actually transmitting torque. During such a situation, the speed s„ at which the worm is turned by the auxiliary motor 3 must be selected to insure that the threads on the worm 2 avoid the teeth on the worm gear 1.

Alternatively, as shown in Figure 14b, during the braking or starting of the system as described above, there will be situations when the direction of rotation of the rotor s _f is in the same direction as the rotation of the worm gear s., and yet it would still be desirable to avoid interaction between the thread on the worm 2 teeth on the worm gear 1. In that situation, the speed of the worms' rotation s must be selected to insure no interaction when it is rotating in the same direction as the worm gear. An appropriate control could be designed by a worker of ordinary skill in this art. When the opposite sign of the oscillating input begins, the initial movement is of the worm gear away from the worm. This provides an unloading of the driving connection between the two, and assists the worm in easily moving freely to roll about the worm gear teeth. Moreover, even if the control does not ensure that the worm is out of engagement with the worm wheel, but is rotating in an opposed direction, the worm wheel motor will be able to overcome the low torque worm auxiliary motor, and thus, there will be no binding between the two. Figure 15 shows an alternative arrangement for the inventive system. An input at shaft 102 drives worm gear 104. Worm gear 104 engages a worm 106, provided with a motor 108 operated on the principles described above. When worm 106 is driven to rotate by the worm gear 104 it will in turn rotate the single housing 110. When housing 110 rotates it rotates worm 112. Worm 112 is also provided

with a motor 114, also operated generally on the principles as described above.

Worm 112 drives worm gear 116 to in turn drive output shaft 118. This arrangement reduces the necessary speed ratio between the input and output shafts.

The input and output speed may differ under certain driving conditions. The output could begin to rotate faster than the input. The motors 108 and 114 have to accommodate that ratio. The speed ratio may be divided between the two motors

108 and 114.

Figure 16 shows a system 130 wherein the input shaft 132 drives the housing

134. Housing 134 drives a worm 136 and its motor 138. Motor 138 is operated according to the principles described above. Worm 136 drives worm gear 140 which drives shaft 142. Shaft 142 rotates housing 144. When housing 144 rotates it rotates worm 146. Worm 146 is controlled by motor 148, again according the principles described above. Worm 146 engages worm gear 150 to drive output shaft 152. This arrangement also assists the motors 138 and 148 to accommodate a speed ratio.

Figure 17 shows yet another system 160. In system 160, input shaft 162 rotates housing 164. Worm 166 rotates with housing 164. Motor 168 controls the worm 166 as with the above described systems. Worm gear 170 is driven by the worm 166, and rotates a shaft 172. Shaft 172 drives a worm gear 174, which in turn drives worm 176. A motor 177 controls the rotation of worm 176. When worm 176 is rotated it drives housing portion 180 to in turn drive output shaft 178. Again, the arrangement assists motors 168 and 177 to accommodate the speed ratio.

Figures 15-17 show that the basic inventive system can be reconfigured into many different mechanical transmissions. Those that are illustrated are by no means exhaustive of all of the possible combinations.

Several embodiments of the present invention have been disclosed. A worker of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.