Gear shift actuator with self-locking

Abstract

The present application relates to a kind of gear shifting actuators with self-locking.The present application includes drive motor, for providing torque;Transmission assembly, connected with the output end of drive motor to transmit the output torque of drive motor;Gear self-locking assembly, including input lock gear and output lock gear, input lock gear receives the torque transmitted by transmission assembly, input lock gear and output lock gear have meshing state, disengagement state and lock state;In meshing state, input lock gear drives output lock gear to rotate when rotating;In disengagement state, input lock gear is disengaged with output lock gear;In lock state, input lock gear blocks the rotation of output lock gear;Output shaft, connected with output lock gear, and can rotate with output lock gear;Gear shifting fork, connected with output shaft, and perform gear shifting function.It can effectively solve the problem of gear shifting fork disengagement when gearbox is twisted.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of automobile transmission technology, in particular to a gear shifting actuator with self-locking. BACKGROUND

[0002] The gear shifting actuator is a main component in the automobile transmission system, which drives the gear shifting according to the instructions from the gear shifting controller.

[0003] At present, the gear shifting actuator mainly drives the shift fork in the gearbox to change the gear position through the air pressure, hydraulic pressure, traditional mechanical type and other ways.

[0004] The original gear shifting actuator with internal gear structure drives the gearbox to shift to the position, and then the gearbox starts to increase the driving torque to accelerate the vehicle. In this process, the gearbox generates a reverse thrust on the shift fork. Influenced by the reverse thrust, the shift fork transmits the reverse thrust to the gear shifting actuator. Because the conventional gear shifting actuator cannot be self-locked, the shift fork is easy to disengage from the original gear position during the acceleration process, resulting in the interruption of the gearbox torque. SUMMARY

[0005] Therefore, the present application provides a gear shifting actuator with self-locking, which can effectively solve the problem of shift fork disengagement when the gearbox increases the torque, and make the gear shifting control simpler, ensure the performance stability of the gearbox shifting process, ensure the safe and stable operation of the vehicle on the road, and make the driving more comfortable.

[0006] To solve the above technical problems, the present application provides a gear shifting actuator with self-locking, comprising:

[0007] A driving motor for providing torque;

[0008] A transmission assembly connected to the output end of the driving motor to transmit the output torque of the driving motor;

[0009] A gear self-locking assembly including an input lock gear and an output lock gear, the input lock gear receiving the torque transmitted by the transmission assembly, the input lock gear and the output lock gear having a meshing state, a disengaging state and a lock 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 lock state, the input lock gear blocks the rotation of the output lock gear;

[0010] An output shaft connected to the output lock gear and capable of rotating with the output lock gear;

[0011] A gear shifting fork connected to the output shaft and performing the gear shifting function.

[0012] In one embodiment of the present application, when the input lock gear rotates in a first rotational direction, the input lock gear and the output lock gear are sequentially shifted from the engaged state, the disengaged state and the locked state;

[0013] When the input lock gear rotates in a second rotational direction, the input lock gear and the output lock gear are sequentially shifted from the locked state, the disengaged state and the engaged state.

[0014] The first rotational direction and the second rotational direction are clockwise or counterclockwise, and the two rotational directions are opposite.

[0015] In one embodiment of the present application, the input lock gear comprises a first gear body and first teeth distributed along a part of the outer periphery of the first gear body, both ends of the first teeth are respectively provided with a first lock structure, the first lock structure comprises a first lock tooth one located at the boundary of the first tooth and a second lock tooth one spaced apart from the first lock tooth one, a lock groove is formed between the first lock tooth one and the second lock tooth one.

[0016] The output lock gear comprises a second gear body and second teeth distributed along a part of the outer periphery of the second gear body and engaged with the first teeth, both ends of the second teeth are respectively provided with a second lock structure, the second lock structure comprises a first lock tooth two spaced apart from the boundary of the second tooth and a second lock tooth two spaced apart from the first lock tooth two.

[0017] When the input lock gear rotates in a first rotational direction, the first lock tooth two enters the lock groove, the input lock gear and the output lock gear are disengaged, the input lock gear continues to rotate in the first rotational direction for a predetermined angle and then stops, when the input lock gear stops rotating and the output lock gear has a tendency to rotate, the second lock tooth two abuts against the second lock tooth one or the tooth at the boundary of the second tooth abuts against the first lock tooth one, so as to enter the locked state.

[0018] In one embodiment of the present application, in the locked state and when the output lock gear has a tendency to rotate, the second lock tooth two abuts against the tooth top of the second lock tooth one or the tooth at the boundary of the second tooth abuts against the tooth top of the first lock tooth one.

[0019] In an embodiment of the present application, the tooth width of the first tooth and the tooth width of the second tooth are equal, the tooth width of the first lock tooth one and the tooth width of the second lock tooth one are both greater than the tooth width of the first tooth, the tooth width of the first lock tooth two and the tooth width of the second lock tooth two are both greater than the tooth width of the second tooth, and the tooth width of the first lock tooth two is less than the lock slot width.

[0020] In an embodiment of the present application, the transmission assembly comprises a first bevel gear connected to the output end of the driving 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.

[0021] In an embodiment of the present application, a buffer assembly is arranged between the second bevel gear and the input end of the planetary gear set.

[0022] In an embodiment of the present application, a magnet mounting seat provided with a magnet is arranged at the middle part of the input lock gear, and one side of the magnet mounting seat is provided with a position sensor matched with the magnet.

[0023] In an embodiment of the present application, an upper shell, a lower shell and a motor shell are further included, the driving 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.

[0024] In an embodiment of the present application, a first bearing, a second bearing, a third bearing and an oil seal are further included, the second bevel gear is installed in the upper shell through the first bearing, one end of the output shaft passes through the output lock gear and is installed in the upper shell through the second bearing, and the other end is installed in the lower shell through the third bearing and the oil seal.

[0025] Compared with the prior art, the above technical solution of the present application has the following advantages:

[0026] The gear self-locking assembly is arranged in the gear shifting execution mechanism with self-locking according to the present application, gear self-locking is realized after gear shifting is completed, it is ensured that the shift fork will not be separated from the original gear position when it is subjected to reverse thrust, and the problem that the shift fork is easily separated from the gear in the process of torque increase of the transmission box in the traditional gear shifting execution mechanism is solved. The introduction of the self-locking mechanism makes the gear shifting control logic simpler, only the lock operation needs to be performed when the gear shifting is completed, a complex control strategy is not needed, and the reliability and response speed of the system are improved.

[0027] The application adopts a planetary gear set for torque transmission, the planetary gear set has a large transmission ratio and a small volume, can realize efficient torque transmission in a limited space, improves the performance of the overall gear shifting execution mechanism, ensures stable and reliable gear shifting action in the gear shifting process, avoids gear shifting failure or abnormality caused by external torque change, and improves the driving safety and stability of the vehicle under various road conditions.

[0028] The application does not need to rely on long-time motor blockage to realize the anti-clutch-out function due to the existence of the self-locking gear mechanism, reduces the energy consumption and heating of the motor, and improves the overall efficiency of the system and the service life of the motor. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to make the content of the application more easily understood, the application will be further described in detail below according to specific embodiments of the application and in combination with the drawings.

[0030] Figure 1 is the overall structure schematic diagram of the gear shifting execution mechanism with self-locking of the application.

[0031] Figure 2 is Figure 1 the local enlarged schematic diagram of

[0032] Figure 3 is the structure schematic diagram of the gear self-locking assembly of the application.

[0033] DESCRIPTION OF DRAWINGS

[0034] 1, driving motor;

[0035] 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;

[0036] 3, input lock gear; 31, first gear body; 32, first tooth; 33, first lock tooth one; 34, second lock tooth one; 35, lock groove; 36, 37, 38,

[0037] 4, output lock gear; 41, second gear body; 42, second tooth; 43, first lock tooth two; 44, second lock tooth two;

[0038] 5, output shaft; 51, driving gear;

[0039] 6, magnet mounting seat;

[0040] 7, position sensor;

[0041] 81, upper housing; 82, lower housing; 83, motor housing; 84, first bearing; 85, second bearing; 86, third bearing; 87, oil seal. DETAILED DESCRIPTION

[0042] The present application will be further described below in conjunction with the drawings and specific embodiments so that those skilled in the art can better understand and implement the present application, but the embodiments are not intended to limit the present application.

[0043] In the present application, if the direction (up, down, left, right, front and back) is described, it is only for the convenience of describing the technical solutions of the present application, and is not intended to indicate or imply that the indicated technical features must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0044] In the present application, the meaning of "several" is one or more, the meaning of "multiple" is two or more, and "greater than", "less than", "exceeding" and the like are understood as not including the number; "above", "below", "within" and the like are understood as including the number. In the description of the present application, if "first" and "second" are described, they are 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 indicated technical features or implicitly indicating the sequence of indicated technical features.

[0045] In the present application, unless otherwise explicitly limited, the words "set", "install", "connect" and the like should be broadly understood, for example, they can be directly connected, or indirectly connected through an intermediate medium; can be fixedly connected, or can be detachably connected, or can be integrally formed; can be mechanically connected, or can be electrically connected or capable of communicating with each other; can be the communication or interaction relationship between two elements or the interaction relationship between two elements. The skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical solutions.

[0046] Referring to Figure 1 The gear shifting actuator with self-locking of the present application comprises:

[0047] The driving motor 1 is used to provide torque;

[0048] The transmission assembly 2 is connected to the output end of the driving motor 1 to transmit the output torque of the driving motor 1;

[0049] The gear self-locking assembly comprises an input lock gear 3 and an output lock gear 4, 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 lock state; wherein, in the meshing state, the input lock gear 3 drives the output lock gear 4 to rotate when the input lock gear 3 rotates; in the disengaging state, the input lock gear 3 is disengaged from the output lock gear 4; in the lock state, the input lock gear 3 blocks the rotation of the output lock gear 4;

[0050] An output shaft 5 is connected with the output lock gear 4 and can rotate with the output lock gear 4;

[0051] A shift fork is connected with the output shaft 5 and performs a shift function.

[0052] Specifically, when the input lock gear 3 rotates in a first rotation direction, the input lock gear 3 and the output lock gear 4 are sequentially changed from the meshing state, the disengaging state and the lock state;

[0053] When the input lock gear 3 rotates in a second rotation direction, the input lock gear 3 and the output lock gear 4 are sequentially changed from the lock state, the disengaging state and the meshing state;

[0054] The first rotation direction and the second rotation direction are clockwise or counterclockwise, and the rotation directions are opposite.

[0055] In one embodiment, referring to Figure 3 The input lock gear 3 comprises a first gear body 31 and first teeth 32 distributed along a part of the outer periphery of the first gear body 31, both ends of the first teeth 32 are respectively provided with a first lock structure, the first lock structure comprises a first lock tooth I 33 located at the boundary of the first teeth 32 and a second lock tooth I 34 arranged at intervals with the first lock tooth I 33, and a lock groove 35 is formed between the first lock tooth I 33 and the second lock tooth I 34;

[0056] The output lock gear 4 comprises a second gear body 41 and second teeth 42 distributed along a part of the outer periphery of the second gear body 41 and meshing with the first teeth 32, both ends of the second teeth 42 are respectively provided with a second lock structure, the second lock structure comprises a first lock tooth II 43 arranged at intervals with the boundary of the second teeth 42 and a second lock tooth II 44 arranged at intervals with the first lock tooth II 43;

[0057] When the input lock gear 3 rotates in the first direction, the first lock gear teeth 43 enter the lock groove 35, the input lock gear 3 is disengaged from the output lock gear 4, the input lock gear 3 continues to rotate in the first direction for a predetermined angle and then stops, and when the output lock gear 4 has a tendency to rotate, the second lock gear teeth 44 abut the second lock gear teeth 34 or the teeth at the boundary of the second teeth 42 abut the first lock gear teeth 33 to enter the lock state.

[0058] The above arrangement helps to precisely control the engagement and disengagement of the input lock gear 3 and the output lock gear 4, ensuring the reliability and accuracy of the lock process.

[0059] It can be understood that when the output lock gear 4 rotates to the shift-in position, the engagement state between the input lock gear 3 and the output lock gear 4 gradually changes to a disengagement state, and finally enters the lock state. In the lock state, the input lock gear 3 blocks the reverse rotation of the output lock gear 4, that is, even if the transmission produces a reverse thrust during the torque increase process, the output lock gear 4 cannot drive the input lock gear 3 in reverse, thereby maintaining the stability of the shift action and the lock state. When it is necessary to unlock or perform a shift operation, the driving motor 1 rotates in reverse, causing the output lock gear 4 to rotate in reverse, so that it re-engages with the input lock gear 3, thereby removing the lock 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 shift action.

[0060] Specifically, in the lock state and when the output lock gear 4 has a tendency to rotate, the second lock gear teeth 44 abut the tooth top of the second lock gear teeth 34 or the teeth at the boundary of the second teeth 42 abut the tooth top of the lock gear teeth 1.

[0061] Referring to Figure 3 As shown in the figure, the tooth width of the first teeth 32 and the tooth width of the second teeth 42 are equal, the tooth width of the first lock gear teeth 33 and the tooth width of the second lock gear teeth 34 are both greater than the tooth width of the first teeth 32, the tooth width of the first lock gear teeth 43 and the tooth width of the second lock gear teeth 44 are both greater than the tooth width of the second teeth 42, and the tooth width of the first lock gear teeth 43 is less than the width of the lock groove 35.

[0062] The above arrangement enhances the lock effect, improves the friction and blocking ability during locking, prevents the output lock gear 4 from reversing when subjected to a reverse force, and ensures that the output lock gear 4 can still be stably locked under high torque.

[0063] In one embodiment, 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 engaged with the first bevel gear 21, and a planetary gear set 23 connected to the second bevel gear 22, and the input lock-up gear 3 is connected to the output end of the planetary gear set 23.

[0064] It should be noted that the planetary gear set 23 can be two stages for transmitting the torque of the drive motor 1 to the input lock-up gear 3. Each stage of the planetary gear set 23 comprises a sun gear, a plurality of first planetary gears 231, and a carrier 232.

[0065] Referring to Figure 2 As 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 comprises coaxially arranged first and second shaft couplings 241 and 242, the first shaft coupling 241 is arranged on the second bevel gear 22, and the second shaft coupling 242 is arranged on the input gear (sun gear of the first stage) of the planetary gear set 23, the first shaft coupling 241 comprises first connecting teeth arranged in a ring shape, the second shaft coupling 242 comprises second connecting teeth arranged in a ring shape and extending into the gaps between adjacent first connecting teeth, and a gap is formed between the first connecting teeth and the second connecting teeth in the rotation direction, and an elastic member is arranged in the gap; the elastic member comprises rubber or polyurethane elastomer, and a spring can also be used. It can be understood that the rotation of the first shaft coupling 241 can drive the second shaft coupling 242 to rotate synchronously. The arrangement of the elastic member can effectively ensure the transmission of the rotation torque and also play a buffering role. During gear shifting, the vibration of the electric drive axle or the transmission may have a reverse impact on the actuator, causing impact and abnormal noise inside the actuator. However, through the arrangement of the elastic member, the impact and abnormal noise inside the actuator can be effectively alleviated, and the driving comfort can be improved.

[0066] By arranging the buffer assembly 24, the reverse impact caused by the vibration of the electric drive axle or the transmission during gear shifting can be effectively alleviated, the impact and abnormal noise inside the actuator can be reduced, and the driving comfort can be improved.

[0067] In one embodiment, a magnet mounting seat 6 provided with a magnet is arranged at the middle part of the input lock-up gear 3, one side of the magnet mounting seat 6 is provided with a position sensor 7 matched with the magnet, and the rotation angle of the input lock-up gear 3 can be detected.

[0068] By arranging the magnet on the input lock-up gear 3 and the matched position sensor 7, the rotation angle of the input lock-up gear 3 can be detected in real time, the accurate control of the gear shifting position can be ensured, and the accuracy and reliability of the gear shifting can be improved.

[0069] In one embodiment, further comprising an upper housing 81, a lower housing 82 and a motor housing 83, the driving 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.

[0070] Further comprising 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, the components are reasonably arranged, and the upper and lower housings 82 are integrated, effectively saving space.

[0071] Exemplarily, in order to realize the shift function, a driving gear 51 is arranged at the end of the output shaft 5, and a rack cooperating with the driving gear 51 is arranged on the shift fork, 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 shift shaft sleeve of the transmission, and the shift is performed when the shift fork moves.

[0072] Working principle: the control system sends a shift command, the driving motor 1 receives the command, the first bevel gear 21 drives the second bevel gear 22, 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 perform the shift action, when the output lock gear 4 is driven to the successful position of the input gear, the input lock gear 3 and the output lock gear 4 are driven to disengage, 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 by a certain angle to complete the lock, so that the output lock gear 4 cannot be driven in reverse when receiving a reverse force, and is kept in the successful position of the input gear, realizing the lock function.

[0073] When unlocking is needed, the driving motor 1 rotates in reverse to drive the first bevel gear 21, 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 reverse to the meshing position of the input lock gear 3, thereby unlocking, and at the same time driving the output lock gear 4 to rotate the output shaft 5, realizing the linear motion of the shift fork and completing the gear shifting action.

[0074] Finally, it should be noted that the above detailed description is merely illustrative of the technical solutions of the present application and is not limiting, and although the present application has been described in detail with reference to the examples, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present application, and all should be covered in the scope of the claims of the present application.

Claims

1. A shift actuator with self-locking, characterized by, The utility model relates to a kind of gear shifters, including: Driving motor (1) for providing torque; Transmission assembly (2) is connected with the output end of the driving motor (1) to transmit the output torque of the driving motor (1); Gear self-locking assembly, including input lock gear (3) and output lock gear (4), the input lock gear (3) receives the torque transmitted by the transmission assembly (2), the input lock gear (3) and the output lock gear (4) have meshing state, disengaging state and lock 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 with the output lock gear (4);In the lock state, the input lock gear (3) blocks the rotation of the output lock gear (4); Output shaft (5) is connected with the output lock gear (4), and can rotate with the output lock gear (4); Shift fork is connected with the output shaft (5), and performs shift function; The input lock gear (3) includes first gear body (31) and first tooth (32) distributed along part of the outer periphery of the first gear body (31), both ends of the first tooth (32) are respectively provided with first lock structure, the first lock structure includes first lock tooth one (33) located at the boundary of the first tooth (32) and second lock tooth one (34) spaced apart from the first lock tooth one (33), lock groove (35) is formed between the first lock tooth one (33) and the second lock tooth one (34); The output lock gear (4) includes second gear body (41) and second tooth (42) distributed along part of the outer periphery of the second gear body (41) and meshing with the first tooth (32), both ends of the second tooth (42) are respectively provided with second lock structure, the second lock structure includes first lock tooth two (43) spaced apart from the boundary of the second tooth (42) and second lock tooth two (44) spaced apart from the first lock tooth two (43); Wherein, when the input lock gear (3) rotates along the first rotation direction, the first lock tooth two (43) enters the lock groove (35), the input lock gear (3) is disengaged with the output lock gear (4), the input lock gear (3) continues to rotate by a predetermined angle along the first rotation direction and stops, when the input lock gear (3) stops rotating and the output lock gear (4) has a rotating trend, the second lock tooth two (44) abuts against the second lock tooth one (34) or the tooth at the boundary of the second tooth (42) abuts against the first lock tooth one (33), to enter the lock state.

2. A shift actuator with self-locking according to claim 1, characterized in that 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 changed by the meshing state, the disengaging state and the lock 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 sequentially changed from the lock state, the disengaged state and the engaged state. The first rotation direction and the second rotation direction are clockwise or counterclockwise, and the rotation directions are opposite.

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

4. The shift actuator with self-locking according to claim 1, characterized in that, The tooth width of the first gear tooth (32) and the tooth width of the second gear tooth (42) are equal, the tooth width of the first lock gear tooth one (33) and the tooth width of the second lock gear tooth one (34) are both greater than the tooth width of the first gear tooth (32), the tooth width of the first lock gear tooth two (43) and the tooth width of the second lock gear tooth two (44) are both greater than the tooth width of the second gear tooth (42), and the tooth width of the first lock gear tooth two (43) is less than the width of the lock groove (35).

5. The shift actuator with self-locking according to claim 1, characterized in that, The transmission assembly (2) comprises a first bevel gear (21) connected to the output end of the driving motor (1), a second bevel gear (22) engaged 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).

6. A shift actuator with self-locking according to claim 5, characterized in that A buffer assembly (24) is arranged between the second bevel gear (22) and the input end of the planetary gear set (23).

7. A shift actuator with self-locking according to claim 6, characterized in that A magnet mounting seat (6) provided with a magnet is arranged at the middle part of the input lock gear (3), and one side of the magnet mounting seat (6) is provided with a position sensor (7) matched with the magnet.

8. A shift actuator with self-locking according to claim 7, characterized in that Further comprising an upper shell (81), a lower shell (82) and a motor shell (83), the driving 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).

9. A shift actuator with self-locking according to claim 8, characterized in that Further comprising 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 shell (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 shell (81) through the second bearing (85), and the other end is installed in the lower shell (82) through the third bearing (86) and the oil seal (87).

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