Gear shifting executing mechanism with self-locking function

Abstract

The invention relates to a gear shifting executing mechanism with a self-locking function. The device comprises a driving motor used for providing torque; the transmission assembly is connected with the output end of the driving motor to transmit the output torque of the driving motor; the gear self-locking assembly comprises an input gear locking gear and an output gear locking gear, the input gear locking gear receives the torque transmitted by the transmission assembly, and the input gear locking gear and the output gear locking gear have an engaged state, a disengaged state and a gear locking state; in the meshing state, the input gear locking gear drives the output gear locking gear to rotate when rotating. In the disengagement state, the input gear locking gear is disengaged from the output gear locking gear; in the gear locking state, the input gear locking gear blocks rotation of the output gear locking gear. The output shaft is connected with the output lock gear and can rotate along with the output lock gear; and the gear shifting fork is connected with the output shaft and performs a gear shifting function. The problem that the shifting fork is out of gear when the gearbox is twisted can be effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of automobile transmission, in particular to a self-locking gear shifting actuator. Background Art

[0002] The shift actuator is a major component in the automobile transmission system, which drives the gear shift according to the instructions issued by the shift controller.

[0003] At present, the gear shift actuator mainly drives the shift fork in the gearbox to change the gear position through air pressure, hydraulic pressure, traditional mechanical methods, etc.

[0004] After the shift actuator with the original internal structure of gears drives the transmission to shift into place, the transmission begins to increase the driving torque to accelerate the vehicle. During this process, the transmission will generate a reverse thrust on the shift fork. Under the influence of the reverse thrust, the shift fork transmits the reverse thrust to the shift actuator. Because the conventional gear shift actuator cannot self-lock, the shift fork can easily disengage from the original gear during acceleration, resulting in transmission torque interruption. Summary of the invention

[0005] To this end, the present invention provides a self-locking shift actuator, which can effectively solve the problem of the shift fork being out of gear when the gearbox is torqued, and at the same time makes the gear shift control simpler, ensures the stable performance of the gearbox shifting process, ensures the safe and smooth operation of the vehicle on the line, and makes driving control more comfortable.

[0006] In order to solve the above technical problems, the present invention provides a self-locking gear shift actuator, comprising: A drive motor for providing torque; A transmission assembly connected to the output end of the drive motor to transmit the output torque of the drive motor; The gear self-locking assembly comprises an input lock gear and an output lock gear, wherein the input lock gear receives the torque transmitted by the transmission assembly, and the input lock gear and the output lock gear have a meshing state, a disengaging state and a locking state; wherein in the meshing state, the input lock gear drives the output lock gear to rotate when rotating; in the disengaging state, the input lock gear is disengaged from the output lock gear; in the locking state, the input lock gear blocks the rotation of the output lock gear; An output shaft connected to the output lock gear and capable of rotating with the output lock gear; The shift fork is connected to the output shaft and performs a shifting function.

[0007] In one embodiment of the present invention, when the input lock gear rotates along the first rotation direction, the input lock gear and the output lock gear are sequentially transformed from the meshing state, the disengaging state and the locking state; When the input lock gear rotates along the second rotation direction, the input lock gear and the output lock gear are sequentially transformed from the lock state, the disengagement state and the meshing state; The first rotation direction and the second rotation direction are clockwise or counterclockwise respectively, and the rotation directions are opposite.

[0008] In one embodiment of the present invention, the input locking gear comprises a first gear body and a first tooth distributed along a portion of the outer circumference of the first gear body, and first locking structures are respectively arranged at both ends of the first tooth, and the first locking structure comprises a first locking tooth 1 located at the boundary of the first tooth and a second locking tooth 1 spaced apart from the first locking tooth 1, and a locking groove is formed between the first locking tooth 1 and the second locking tooth 1; The output locking gear comprises a second gear body and a second tooth distributed along a portion of the outer circumference of the second gear body and meshing with the first tooth, and a second locking structure is respectively provided at both ends of the second tooth, and the second locking structure comprises a first locking tooth 2 spaced apart from the boundary of the second tooth and a second locking tooth 2 spaced apart from the first locking tooth 2; Among them, when the input locking gear rotates along the first rotation direction, the first locking tooth 2 enters the locking groove, the input locking gear is disengaged from the output locking gear, and the input locking gear continues to rotate along the first rotation direction by a predetermined angle and then stops. When the input locking gear stops rotating and the output locking gear has a tendency to rotate, the second locking tooth 2 abuts against the second locking tooth 1 or the tooth at the boundary of the second tooth abuts against the first locking tooth 1 to enter the locking state.

[0009] In one embodiment of the present invention, in the locking state and when the output locking gear tends to rotate, the second locking tooth 2 abuts against the tooth top of the second locking tooth 1 or the tooth at the boundary of the second tooth abuts against the tooth top of the locking tooth 1.

[0010] In one embodiment of the present invention, the tooth width of the first tooth is equal to the tooth width of the second tooth, the tooth width of the first locking tooth one and the tooth width of the second locking tooth one are both greater than the tooth width of the first tooth, the tooth width of the first locking tooth two and the tooth width of the second locking tooth two are both greater than the tooth width of the second tooth, and the tooth width of the first locking tooth two is smaller than the width of the locking groove.

[0011] In one embodiment of the present invention, the transmission assembly includes a first bevel gear connected to the output end of the drive motor, a second bevel gear meshing with the first bevel gear, and a planetary gear set connected to the second bevel gear, and the input lock gear is connected to the output end of the planetary gear set.

[0012] In one embodiment of the present invention, a buffer assembly is provided between the second bevel gear and the input end of the planetary gear set.

[0013] In one embodiment of the present invention, a magnet mounting seat with a magnet mounted thereon is disposed in the middle of the input lock gear, and a position sensor cooperating with the magnet is disposed on one side of the magnet mounting seat.

[0014] In one embodiment of the present invention, it also includes an upper shell, a lower shell and a motor shell, the drive motor is installed in the motor shell, the motor shell, the position sensor and the planetary gear set are all installed in the upper shell, and the output shaft is installed between the upper shell and the lower shell.

[0015] In one embodiment of the present invention, it also includes a first bearing, a second bearing, a third bearing and an oil seal. The second bevel gear is installed in the upper housing through the first bearing. One end of the output shaft passes through the output lock gear and is installed on the upper housing through the second bearing, and the other end is installed on the lower housing through the third bearing and the oil seal.

[0016] The above technical solution of the present invention has the following advantages compared with the prior art: The self-locking gear shift actuator described in the present invention realizes gear self-locking after the gear shift is in place by setting a gear self-locking component, ensuring that the shift fork will not be disengaged from the original gear position when subjected to reverse thrust, thereby solving the problem that the traditional gear shift actuator is prone to causing the shift fork to be disengaged during the torque addition process of the gearbox. The introduction of the self-locking mechanism makes the gear shift control logic simpler, and only needs to perform the gear lock operation when the gear shift is in place, without the need for complex control strategies, thereby improving the reliability and response speed of the system.

[0017] The present invention adopts a planetary gear set for torque transmission. The planetary gear set has a large transmission ratio and a small volume, and can achieve efficient torque transmission in a limited space, thereby improving the performance of the overall shift actuator, ensuring that the shift action is stable and reliable during the shift process, avoiding shift failure or abnormality caused by external torque changes, and improving the driving safety and stability of the vehicle under various road conditions.

[0018] Due to the existence of the self-locking gear mechanism, the present invention does not need to rely on the motor to be locked for a long time to achieve the anti-shifting function, thereby reducing the energy consumption and heat generation of the motor and improving the overall efficiency of the system and the service life of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0020] Figure 1 It is a schematic diagram of the overall structure of the self-locking gear shift actuator of the present invention.

[0021] Figure 2 yes Figure 1 A partial enlarged schematic diagram of .

[0022] Figure 3 It is a structural schematic diagram of the gear self-locking assembly of the present invention.

[0023] Description of the Figures in the Specification: 1. Drive motor; 2. Transmission assembly; 21. First bevel gear; 22. Second bevel gear; 23. Planetary gear set; 231. First planetary gear; 232. Planet carrier; 24. Buffer assembly; 241. First coupling; 242. Second coupling; 3. Input lock gear; 31. First gear body; 32. First tooth; 33. First lock gear 1; 34. Second lock gear 1; 35. Lock groove; 36; 37; 38; 4. Output lock gear; 41. Second gear body; 42. Second tooth; 43. First lock gear second; 44. Second lock gear second; 5. Output shaft; 51. Driving gear; 6. Magnet mounting base; 7. Position sensor; 81. Upper housing; 82. Lower housing; 83. Motor housing; 84. First bearing; 85. Second bearing; 86. Third bearing; 87. Oil seal. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0025] In the present invention, if directions (up, down, left, right, front and back) are described, it is only for the convenience of describing the technical solution of the present invention, and does not indicate or imply that the technical features referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, it cannot be understood as a limitation of the present invention.

[0026] In the present invention, "several" means one or more, "multiple" means more than two, "greater than", "less than", "exceed" and the like are understood to exclude the number itself; "above", "below", "within" and the like are understood to include the number itself. In the description of the present invention, if there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0027] In the present invention, unless otherwise clearly defined, the words "set", "install", "connect" and the like should be understood in a broad sense, for example, they can be directly connected or indirectly connected through an intermediate medium; they can be fixedly connected or detachably connected or integrally formed; they can be mechanically connected or electrically connected or able to communicate with each other; they can be the internal connection of two elements or the interaction relationship between two elements. Those skilled in the art can reasonably determine the specific meanings of the above words in the present invention in combination with the specific content of the technical solution.

[0028] Reference Figure 1 As shown, a self-locking shift actuator of the present invention comprises: A driving motor 1, for providing torque; A transmission assembly 2, connected to an output end of the drive motor 1 to transmit an output torque of the drive motor 1; The gear self-locking assembly comprises an input lock gear 3 and an output lock gear 4, wherein the input lock gear 3 receives the torque transmitted by the transmission assembly 2, and the input lock gear 3 and the output lock gear 4 have a meshing state, a disengaging state and a locking state; wherein in the meshing state, the input lock gear 3 drives the output lock gear 4 to rotate when rotating; in the disengaging state, the input lock gear 3 is disengaged from the output lock gear 4; in the locking state, the input lock gear 3 blocks the rotation of the output lock gear 4; An output shaft 5 is connected to the output lock gear 4 and can rotate with the output lock gear 4; The shift fork is connected to the output shaft 5 and performs a shifting function.

[0029] Specifically, when the input lock gear 3 rotates along the first rotation direction, the input lock gear 3 and the output lock gear 4 are sequentially transformed from the meshing state, the disengaging state and the locking state; When the input lock gear 3 rotates along the second rotation direction, the input lock gear 3 and the output lock gear 4 are sequentially transformed from the lock state, the disengagement state and the meshing state; The first rotation direction and the second rotation direction are clockwise or counterclockwise respectively, and the rotation directions are opposite.

[0030] In one embodiment, referring to Figure 3 As shown, the input locking gear 3 includes a first gear body 31 and a first tooth 32 distributed along a portion of the outer circumference of the first gear body 31, and first locking structures are respectively provided at both ends of the first tooth 32, and the first locking structure includes a first locking tooth 33 located at the boundary of the first tooth 32 and a second locking tooth 34 spaced from the first locking tooth 33, and a locking groove 35 is formed between the first locking tooth 33 and the second locking tooth 34; The output locking gear 4 includes a second gear body 41 and a second tooth 42 distributed along a portion of the outer circumference of the second gear body 41 and meshing with the first tooth 32, and a second locking structure is respectively provided at both ends of the second tooth 42, and the second locking structure includes a first locking tooth 43 spaced apart from the boundary of the second tooth 42 and a second locking tooth 44 spaced apart from the first locking tooth 43; Among them, when the input locking gear 3 rotates along the first rotation direction, the first locking tooth 2 43 enters the locking groove 35, the input locking gear 3 is disengaged from the output locking gear 4, and the input locking gear 3 continues to rotate along the first rotation direction by a predetermined angle and then stops. When the input locking gear 3 stops rotating and the output locking gear 4 has a rotation tendency, the second locking tooth 2 44 abuts against the second locking tooth 1 34 or the tooth at the boundary of the second tooth 42 abuts against the first locking tooth 1 33 to enter the locking state.

[0031] The above arrangement helps to precisely control the engagement and disengagement of the input lock gear 3 and the output lock gear 4, thereby ensuring the reliability and accuracy of the lock process.

[0032] It is understandable that when the output lock gear 4 rotates to the shift position, the meshing state between the input lock gear 3 and the output lock gear 4 gradually changes to a disengaged state, and finally enters a locked state. In the locked state, the input lock gear 3 blocks the reverse rotation of the output lock gear 4. Even if the gearbox generates a reverse thrust during the torque application process, the output lock gear 4 cannot reversely drive the input lock gear 3, thereby maintaining the stability and locked state of the shifting action. When unlocking or disengaging is required, the drive motor 1 rotates in the reverse direction, causing the output lock gear 4 to rotate in the reverse direction, causing it to re-engage with the input lock gear 3 and release the locked state. At the same time, the output lock gear 4 drives the output shaft 5 to rotate, realizing the linear motion of the shift fork and completing the disengaging action.

[0033] Specifically, in the locking state and when the output locking gear 4 has a tendency to rotate, the second locking tooth 2 44 abuts against the tooth top of the second locking tooth 1 34 or the tooth at the boundary of the second tooth 42 abuts against the tooth top of the locking tooth 1.

[0034] Reference Figure 3 As shown, the tooth width of the first tooth 32 is equal to the tooth width of the second tooth 42, the tooth width of the first locking tooth 33 and the tooth width of the second locking tooth 34 are both larger than the tooth width of the first tooth 32, the tooth width of the first locking tooth 43 and the tooth width of the second locking tooth 44 are both larger than the tooth width of the second tooth 42, and the tooth width of the first locking tooth 43 is smaller than the width of the locking groove 35.

[0035] The above arrangement enhances the locking effect, improves the friction and blocking ability during locking, prevents the output locking gear 4 from reversing when subjected to a reverse force, and ensures that the output locking gear 4 can still be stably locked under high torque conditions.

[0036] In one embodiment, the transmission assembly 2 includes a first bevel gear 21 connected to the output end of the drive motor 1, a second bevel gear 22 meshing with the first bevel gear 21, and a planetary gear set 23 connected to the second bevel gear 22, and the input lock gear 3 is connected to the output end of the planetary gear set 23.

[0037] It should be noted that the planetary gear set 23 may be two-stage, for transmitting the torque of the drive motor 1 to the input lock gear 3. Each stage of the planetary gear set 23 includes a sun gear, a plurality of first planetary gears 231 and a planet carrier 232.

[0038] Reference Figure 2As shown, a buffer assembly 24 is provided between the second bevel gear 22 and the input end of the planetary gear set 23. Specifically, the buffer assembly 24 includes a first coupling 241 and a second coupling 242 which are coaxially arranged. The first coupling 241 is arranged on the second bevel gear 22, and the second coupling 242 is arranged on the input gear (the first-stage sun gear) of the planetary gear set 23. The first coupling 241 includes first connecting teeth arranged at intervals along the circumferential direction, and the second coupling 242 includes second connecting teeth arranged along the circumferential direction and extending between adjacent first connecting teeth. A gap is formed between the first connecting teeth and the second connecting teeth in the rotation direction, and an elastic member is provided in the gap; the elastic member includes rubber, or polyurethane elastomer, or a spring. It can be understood that the rotation of the first coupling 241 can drive the second coupling 242 to rotate synchronously. The provision of the elastic member can not only effectively ensure the transmission of the rotational torque, but also play a buffering role. During the gear shifting process, the vibration of the electric drive axle or gearbox may have a reverse impact on the actuator, causing collisions inside the actuator and generating abnormal noise. The setting of elastic parts can effectively alleviate this impact and reduce the occurrence of abnormal noise.

[0039] By providing the buffer assembly 24, the reverse impact caused by the vibration of the electric drive axle or the gearbox during the gear shifting process can be effectively alleviated, the impact and abnormal noise inside the actuator can be reduced, and the driving comfort can be improved.

[0040] In one embodiment, a magnet mounting seat 6 with a magnet mounted thereon is disposed in the middle of the input lock gear 3 , and a position sensor 7 cooperating with the magnet is disposed on one side of the magnet mounting seat 6 to detect the rotation angle of the input lock gear 3 .

[0041] By installing a magnet and a matching position sensor 7 on the input lock gear 3, the rotation angle of the input lock gear 3 can be detected in real time, ensuring accurate control of the shift position and improving the accuracy and reliability of the shift.

[0042] In one embodiment, it also includes an upper shell 81, a lower shell 82 and a motor shell 83, the drive motor 1 is installed in the motor shell 83, the motor shell 83, the position sensor 7 and the planetary gear set 23 are all installed in the upper shell 81, and the output shaft 5 is installed between the upper shell 81 and the lower shell 82.

[0043] In addition, it also includes a first bearing 84, a second bearing 85, a third bearing 86 and an oil seal 87. The second bevel gear 22 is installed in the upper housing 81 through the first bearing 84. One end of the output shaft 5 passes through the output lock gear 4 and is installed in the upper housing 81 through the second bearing 85, and the other end is installed in the lower housing 82 through the third bearing 86 and the oil seal 87. The internal structure of the shift actuator is compact, and each component is reasonably arranged and integrated in the upper and lower housings 82, which effectively saves space.

[0044] For example, in order to realize the shifting function, a driving gear 51 is provided at the end of the output shaft 5, and a rack matched with the driving gear 51 is installed on the shift fork, and the driving gear 51 drives the rack of the shift fork to realize the linear motion of the shift fork. It can be understood that the shift fork can cooperate with the electric drive axle or the gearbox shift shaft sleeve to shift gears when it moves through it.

[0045] Working principle: the control system sends out a shift command, the drive motor 1 receives the command and drives the second bevel gear 22 from the first bevel gear 21, the second bevel gear 22 transmits torque to the planetary gear set 23 through the buffer assembly 24, the planetary gear set 23 drives the input lock gear 3, the input lock gear 3 drives the output lock gear 4 to rotate, the output lock gear 4 drives the output shaft 5 to rotate to shift gears, when the output lock gear 4 is driven to the position of successful gear entry, the input lock gear 3 and the output lock gear 4 drive meshing disengagement, the input lock gear 3 cannot continue to drive the output lock gear 4, at this time the input lock gear 3 continues to rotate a certain angle to complete the lock, so that when the output lock gear 4 receives the reverse force, it cannot reversely drive the input lock gear 3, and remains in the successful gear entry position to achieve the lock function.

[0046] When unlocking is required, the driving motor 1 rotates in the reverse direction to drive the first bevel gear 21, and the first bevel gear 21 transmits torque to the planetary gear set 23 through the buffer. The planetary gear set 23 drives the output lock gear 4 to rotate in the reverse direction to a position meshing with the input lock gear 3, thereby releasing the lock and driving the output lock gear 4 to drive the output shaft 5 to rotate, thereby realizing the linear movement of the shift fork and completing the gear disengagement action.

[0047] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A self-locking gear shift actuator, characterized in that: include: A drive motor (1) for providing torque; A transmission assembly (2) connected to an output end of the drive motor (1) to transmit an output torque of the drive motor (1); The gear self-locking assembly comprises an input lock gear (3) and an output lock gear (4), wherein the input lock gear (3) receives the torque transmitted by the transmission assembly (2), and the input lock gear (3) and the output lock gear (4) are in a meshing state, a disengaging state and a locking state; wherein in the meshing state, the input lock gear (3) drives the output lock gear (4) to rotate when rotating; in the disengaging state, the input lock gear (3) is disengaged from the output lock gear (4); and in the locking state, the input lock gear (3) blocks the rotation of the output lock gear (4); An output shaft (5) connected to the output lock gear (4) and capable of rotating along with the output lock gear (4); A shift fork is connected to the output shaft (5) and performs a shifting function.

2. A self-locking shift actuator according to claim 1, characterized in that: When the input lock gear (3) rotates in the first rotation direction, the input lock gear (3) and the output lock gear (4) are transformed in sequence from the meshing state, the disengaging state and the locking state; When the input lock gear (3) rotates in the second rotation direction, the input lock gear (3) and the output lock gear (4) are transformed in sequence from the lock state, the disengagement state and the meshing state; The first rotation direction and the second rotation direction are clockwise or counterclockwise respectively, and the rotation directions are opposite.

3. A self-locking shift actuator according to claim 2, characterized in that: The input locking gear (3) comprises a first gear body (31) and a first tooth (32) distributed along a portion of the outer circumference of the first gear body (31), and first locking structures are respectively arranged at both ends of the first tooth (32), and the first locking structure comprises a first locking tooth (33) located at the boundary of the first tooth (32) and a second locking tooth (34) arranged at a distance from the first locking tooth (33), and a locking groove (35) is formed between the first locking tooth (33) and the second locking tooth (34); The output locking gear (4) comprises a second gear body (41) and a second tooth (42) distributed along a portion of the outer circumference of the second gear body (41) and meshing with the first tooth (32), and second locking structures are respectively provided at both ends of the second tooth (42), and the second locking structure comprises a first locking tooth (43) spaced from the boundary of the second tooth (42) and a second locking tooth (44) spaced from the first locking tooth (43); When the input lock gear (3) rotates in the first rotation direction, the first lock gear 2 (43) enters the lock groove (35), the input lock gear (3) is disengaged from the output lock gear (4), and the input lock gear (3) continues to rotate in the first rotation direction by a predetermined angle and then stops. When the input lock gear (3) stops rotating and the output lock gear (4) has a tendency to rotate, the second lock gear 2 (44) abuts against the second lock gear 1 (34) or the tooth at the boundary of the second tooth (42) abuts against the first lock gear 1 (33), so as to enter the locking state.

4. A self-locking shift actuator according to claim 3, characterized in that: In the locking state and when the output locking gear (4) has a tendency to rotate, the second locking tooth 2 (44) abuts against the tooth top of the second locking tooth 1 (34), or the tooth at the boundary of the second tooth (42) abuts against the tooth top of the locking tooth 1.

5. A self-locking shift actuator according to claim 3, characterized in that: The tooth width of the first tooth (32) is equal to the tooth width of the second tooth (42); the tooth width of the first locking tooth (33) and the tooth width of the second locking tooth (34) are both greater than the tooth width of the first tooth (32); the tooth width of the first locking tooth (43) and the tooth width of the second locking tooth (44) are both greater than the tooth width of the second tooth (42); and the tooth width of the first locking tooth (43) is smaller than the width of the locking groove (35).

6. A self-locking shift actuator according to claim 1, characterized in that: The transmission assembly (2) comprises a first bevel gear (21) connected to the output end of the drive motor (1), a second bevel gear (22) meshing with the first bevel gear (21), and a planetary gear set (23) connected to the second bevel gear (22), and the input lock gear (3) is connected to the output end of the planetary gear set (23).

7. A self-locking shift actuator according to claim 6, characterized in that: A buffer assembly (24) is provided between the second bevel gear (22) and the input end of the planetary gear set (23).

8. A self-locking shift actuator according to claim 7, characterized in that: A magnet mounting seat (6) on which a magnet is mounted is provided in the middle of the input lock gear (3), and a position sensor (7) cooperating with the magnet is provided on one side of the magnet mounting seat (6).

9. A self-locking shift actuator according to claim 8, characterized in that: The invention also comprises an upper housing (81), a lower housing (82) and a motor housing (83), wherein the drive motor (1) is installed in the motor housing (83), the motor housing (83), the position sensor (7) and the planetary gear set (23) are all installed in the upper housing (81), and the output shaft (5) is installed between the upper housing (81) and the lower housing (82).

10. A self-locking shift actuator according to claim 9, characterized in that: It also includes a first bearing (84), a second bearing (85), a third bearing (86) and an oil seal (87); the second bevel gear (22) is mounted in the upper housing (81) via the first bearing (84); one end of the output shaft (5) passes through the output lock gear (4) and is mounted on the upper housing (81) via the second bearing (85); and the other end is mounted on the lower housing (82) via the third bearing (86) and the oil seal (87).

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