Speed change device

Abstract

The invention discloses a speed change device, and relates to the field of riding vehicles. According to the technical scheme, the gearbox comprises a speed change mechanism, a gear shifting executing mechanism, a main gear shifting driving mechanism, an auxiliary gear shifting driving mechanism and an output shell. The gear shifting executing mechanism comprises a gear shifting rotating sleeve, a transmission base linked with the gear shifting rotating sleeve in the circumferential direction, a transmission ring and a transmission torsional spring arranged between the transmission base and the transmission ring. The speed changing device comprises a single-mechanism gear shifting driving working condition and a double-mechanism gear shifting driving working condition. On the basis of the main gear shifting driving mechanism, the auxiliary gear shifting driving mechanism is adopted, the torque from the speed change device can be automatically provided to assist in driving the gear shifting rotating sleeve to rotate when gear shifting is blocked, so that smooth execution of the gear shifting action is promoted, and the user experience is optimized; the auxiliary gear shifting driving mechanism bears the internal driving force of the speed change device, extra control is not needed, the structure can be greatly simplified, cost is reduced, and arrangement is convenient.

Description

Technical Field

[0001] The present invention relates to the field of riding vehicles, and more particularly to a speed changing device. Background Art

[0002] In a speed change mechanism of a bicycle, multiple pawls are usually used to achieve gear switching.

[0003] The existing Chinese patent with authorization announcement number CN221477422U discloses a hub motor with an integrated speed change mechanism, which includes a shift adjustment assembly, which includes a plurality of pawls respectively embedded in the central shaft and a shift sleeve sleeve mounted on the central shaft, and the shift sleeve is used to control the pawls to pop up or retract; the shift adjustment assembly also includes a drive sleeve connected to the shift sleeve, and a cable plate mounted on the drive sleeve, and a flexible connection is achieved between the cable plate and the drive sleeve through an elastic member.

[0004] However, when climbing a slope or accelerating, the pawl is under stress, and the resistance to shifting gears is very large. The gears may not be switched, affecting the riding experience. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a speed transmission device, which adopts an auxiliary shift drive mechanism on the basis of the main shift drive mechanism, which can automatically provide torque from the speed transmission device itself to assist in driving the shift sleeve to rotate when the gear shift is blocked, thereby promoting the smooth execution of the gear shift action and optimizing the user experience; the auxiliary shift drive mechanism takes over the internal driving force of the speed transmission device itself, does not require additional control, can greatly simplify the structure, reduce costs, and is convenient for layout.

[0006] To achieve the above object, the present invention provides the following technical solutions: A speed change device includes a speed change mechanism, a shift actuator, a main shift drive mechanism, and an output housing; The shift actuator includes a shift sleeve, a transmission seat circumferentially linked to the shift sleeve, a transmission ring, and a transmission torsion spring disposed between the transmission seat and the transmission ring; The speed change device further includes an auxiliary shift drive mechanism, wherein the auxiliary shift drive mechanism includes an engaged state and a disengaged state; The speed change device includes a single-mechanism shift drive working condition and a dual-mechanism shift drive working condition; Single-mechanism shift drive working condition: The main shift drive mechanism controls the rotation of the transmission ring, and then drives the transmission seat to rotate through the transmission torsion spring; at this time, the auxiliary shift drive mechanism is in a disengaged state; Dual-mechanism shift drive working condition: the main shift drive mechanism controls the rotation of the transmission ring, and the driving force of the transmission torsion spring is less than the resistance of the transmission seat, so that the transmission ring rotates relative to the transmission seat, thereby switching the auxiliary shift drive mechanism from the disengaged state to the engaged state; then, the torque of the speed change mechanism or the output housing is transmitted to the transmission seat via the auxiliary shift drive mechanism; after the shift is completed, the auxiliary shift drive mechanism switches to the disengaged state.

[0007] Furthermore, the auxiliary shift drive mechanism includes a shift clutch assembly and a clutch control member; The shift clutch assembly includes a clutch inner ring, a plurality of clutch members, and a clutch outer ring; the clutch inner ring is linked to the transmission seat along the circumferential direction, and the clutch outer ring is used to receive torque from the speed change mechanism or the output housing; The clutch control member is used to open or close the clutch member, so that the auxiliary shift drive mechanism switches between an engaged state and a disengaged state.

[0008] Furthermore, the clutch inner ring and the transmission seat are integrally formed.

[0009] Furthermore, the multiple clutch components include a forward clutch component and a reverse clutch component; in the dual-mechanism shift drive working condition, the main shift drive mechanism controls the transmission ring to rotate forward or reverse, and the shift clutch assembly is in an engaged state through the forward clutch component or the reverse clutch component.

[0010] Furthermore, the shift clutch assembly also includes a drive ring connected to the speed change mechanism or the output housing, and a flexible transmission member arranged between the drive ring and the clutch outer ring; through the flexible transmission member, the drive ring and the clutch outer ring include a transmission state and an overrunning state.

[0011] Furthermore, the flexible transmission part includes a transmission retaining spring; the outer side wall of the transmission retaining spring is provided with a plurality of transmission protrusions, and the drive ring is provided with a transmission retaining groove that cooperates with the transmission protrusions; the inner side wall of the transmission retaining spring is provided with a plurality of transmission teeth, and the outer side wall of the clutch outer ring is provided with a transmission gear ring that cooperates with the transmission teeth.

[0012] Furthermore, the number of the transmission teeth is smaller than the number of tooth grooves of the transmission gear ring.

[0013] Furthermore, the clutch control member and the transmission ring are linked in the circumferential direction to open or close the clutch member.

[0014] Furthermore, the clutch control component includes a limit ring located between the clutch inner ring and the clutch outer ring, and the limit ring is provided with a plurality of release holes arranged at intervals along the circumferential direction; when shifting gears, the clutch component is opened through the release holes; after the gear shift is completed, the limit ring closes the clutch component.

[0015] Furthermore, the outer side wall of the transmission seat is provided with an annular cavity, and the two opposite inner side walls of the annular cavity are respectively provided with a first arc groove and a second arc groove; The transmission torsion spring is arranged in the annular cavity, and the two ends of the transmission torsion spring are respectively provided with a first blocking rod extending into the first arc groove and a second blocking rod extending into the second arc groove; The inner side wall of the transmission ring is respectively provided with a first boss for cooperating with the first gear lever, and a second boss for cooperating with the second gear lever; When the transmission ring rotates forward, the first boss drives the first shift lever to rotate, and the second shift lever contacts the inner end surface of the second arc groove under the action of elastic force, and drives the transmission seat to rotate forward; When the transmission ring rotates reversely, the second boss drives the second shift lever to rotate, and the first shift lever contacts the inner end surface of the first arc groove under the action of elastic force, and drives the transmission seat to reverse.

[0016] In summary, the present invention has the following beneficial effects: 1. Use transmission torsion springs to achieve bidirectional flexible transmission, which can improve the smoothness of gear shifting and reduce the risk of damage to electric drive components; 2. Based on the main shift drive mechanism, an auxiliary shift drive mechanism is adopted. It can automatically provide torque from the transmission itself to assist in driving the shift sleeve to rotate when shifting is blocked, thereby promoting smooth shifting and optimizing the user experience. The auxiliary shift drive mechanism takes over the internal driving force of the transmission itself and does not require additional control, which can greatly simplify the structure, reduce costs, and facilitate layout. 3. After the structure of the circlip is improved, a transmission circlip is formed, which can be arranged in a narrow space to achieve flexible transmission, protect the mechanism, and facilitate assembly; 4. Using a small number of transmission teeth in conjunction with a full circle of transmission gear ring is conducive to entering the overtaking state while ensuring torque transmission, and can quickly switch from the overtaking state to the transmission state. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the structure of the speed change device in the embodiment Figure 1 ; Figure 2 Schematic diagram of the structure of the speed change device in the embodiment Figure 2 ; Figure 3 Schematic diagram of the structure of the shift actuator, main shift drive mechanism and auxiliary shift drive mechanism in the embodiment Figure 1 ; Figure 4 Schematic diagram of the structure of the shift actuator, main shift drive mechanism and auxiliary shift drive mechanism in the embodiment Figure 2; Figure 5 Schematic diagram of the structure of the shift actuator, main shift drive mechanism and auxiliary shift drive mechanism in the embodiment Figure 3 ; Figure 6 Schematic diagram of the structure of the shift actuator, main shift drive mechanism and auxiliary shift drive mechanism in the embodiment Figure 4 ; Figure 7 Schematic diagram of the structure of the speed change mechanism and the auxiliary shift drive mechanism in the embodiment.

[0018] In the figure: 1. middle shaft; 2. output housing; 3. speed change mechanism; 31. planetary carrier; 4. shift actuator; 41. shift pawl; 42. shift sleeve; 43. transmission seat; 431. annular cavity; 432. first arc groove; 433. second arc groove; 44. transmission ring; 441. first boss; 442. second boss; 45. transmission torsion spring; 451. first gear lever; 452. second gear lever; 5. main shift drive mechanism; 6. auxiliary shift drive mechanism; 61. clutch inner ring; 62. clutch member; 63. clutch retaining ring; 64. clutch outer ring; 641. transmission ring gear; 65. drive ring; 651. transmission retaining groove; 66. transmission retaining spring; 661. transmission protrusion; 662. transmission tooth; 67. limit ring; 671. release hole. DETAILED DESCRIPTION

[0019] The present invention will be further described in detail below with reference to the accompanying drawings.

[0020] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed. However, as long as such modifications are within the scope of the claims of the present invention, they are protected by patent law. Example

[0021] A speed change device, referring to Figures 1 to 7 , which includes a central shaft 1, an output housing 2, a speed change mechanism 3, a shift actuator 4, a main shift drive mechanism 5 and an auxiliary shift drive mechanism 6; the central shaft 1 is fixed, and the torque is input from the speed change mechanism 3 and then output through the output housing 2; the speed change mechanism 3 has multiple gears, and the shift actuator 4 directly cooperates with the speed change mechanism 3 to perform gear switching. The main shift drive mechanism 5 and the auxiliary shift drive mechanism 6 respectively provide power to the shift actuator 4; among them, the main shift drive mechanism 5 can adopt a manual drive mechanism or an electric drive mechanism, which is not limited here; in this embodiment, the main shift drive mechanism 5 is an electric drive mechanism, which is directly arranged in the output housing 2.

[0022] Reference Figures 1 to 7Specifically, the shift actuator 4 includes a shift sleeve 42, a transmission seat 43 circumferentially linked to the shift sleeve 42, a transmission ring 44, and a transmission torsion spring 45 arranged between the transmission seat 43 and the transmission ring 44; the shift actuator 4 also includes a plurality of shift actuators, such as a shift pawl 41 embedded on the central shaft 1; the shift sleeve 42 controls the actions of the shift actuators respectively by rotating, thereby realizing gear switching; wherein, the shift sleeve 42 and the transmission seat 43 rotate synchronously, and the transmission ring 44 and the transmission seat 43 realize circumferential transmission through the transmission torsion spring 45.

[0023] Reference Figures 1 to 7 In this embodiment, the main shift drive mechanism 5 includes a drive motor and a drive gear, and the drive gear is engaged with the transmission ring 44; then, the main shift drive mechanism 5 controls the transmission ring 44 to rotate forward or reverse, and then drives the transmission seat 43 and the shift sleeve 42 to rotate forward or reverse through the transmission torsion spring 45, thereby performing gear switching; the use of the transmission torsion spring 45 can achieve bidirectional flexible transmission, which can improve the smoothness of gear shifting and reduce the risk of damage to the electric drive components.

[0024] Reference Figures 1 to 7 Specifically, the outer wall of the transmission seat 43 is provided with an annular cavity 431, the transmission ring 44 is sleeved on the transmission seat 43, and the inner wall of the transmission ring 44 is provided with a limiting convex ring embedded in the annular cavity 431; wherein, the transmission ring 44 can rotate relative to the transmission seat 43, and the limiting convex ring can realize axial limitation between the transmission ring 44 and the transmission seat 43; the two opposite inner walls of the annular cavity 431 are respectively provided with a first arc groove 432 and a second arc groove 433; the transmission torsion spring 45 is provided in the annular cavity 431, and the two ends of the transmission torsion spring 45 are respectively provided with a first blocking rod 451 extending into the first arc groove 432, and a second blocking rod 452 extending into the second arc groove 433; the inner wall of the transmission ring 44 is respectively provided with a first boss 441 cooperating with the first blocking rod 451, and a second boss 442 cooperating with the second blocking rod 452.

[0025] Reference Figures 1 to 7When the transmission ring 44 rotates forward, the first boss 441 drives the first gear rod 451 to rotate. The second gear rod 452 contacts the inner end surface of the second arc groove 433 under the action of elastic force, and drives the transmission seat 43 to rotate forward, and the transmission seat 43 drives the shift sleeve 42 to rotate forward. When the transmission ring 44 rotates backward, the second boss 442 drives the second gear rod 452 to rotate. The first gear rod 451 contacts the inner end surface of the first arc groove 432 under the action of elastic force, and drives the transmission seat 43 to rotate backward, and the transmission seat 43 drives the shift sleeve 42 to rotate backward. In this embodiment, the transmission torsion spring 45 is in a pre-stressed state when installed, and there is a pre-stressed elastic force, which can make the first gear rod 451 and the second gear rod 452 respectively in a state of conflict, so that they can follow the rotation in time to ensure the accuracy of the gear position. In this embodiment, the transmission torsion spring 45 is used to achieve bidirectional flexible transmission, which can improve the smoothness of gear shifting and reduce the risk of damage to the electric drive component.

[0026] Reference Figures 1 to 7 Based on the main shift drive mechanism 5 and the auxiliary shift drive mechanism 6, the speed change device in this embodiment includes a single-mechanism shift drive condition and a dual-mechanism shift drive condition; when the shift resistance is small, the single-mechanism shift drive condition is executed, and the shift can be smoothly achieved only by the main shift drive mechanism 5 providing the driving force, while the auxiliary shift drive mechanism 6 does not provide the driving force; when the shift resistance is large, the auxiliary shift drive mechanism automatically intervenes and provides the driving force, cooperating with the main shift drive mechanism to execute the dual-mechanism shift drive condition, thereby promoting the smooth execution of the shift action.

[0027] Reference Figures 1 to 7 In the single-mechanism shifting drive condition, the shifting resistance is small, the main shifting drive mechanism controls the transmission ring 44 to rotate, and then drives the transmission seat 43 to rotate through the transmission torsion spring 45, and the transmission seat 43 drives the shift sleeve 42 to rotate, thereby performing the shifting action; it can be understood that when the shifting resistance is small, the transmission torsion spring 45 has almost no twisting, which is equivalent to the transmission ring 44, the transmission torsion spring 45 and the transmission seat 43 rotating synchronously.

[0028] During the dual-mechanism shifting drive working condition, the shifting resistance is large, and the main shifting drive mechanism controls the transmission ring 44 to rotate, but the driving force of the transmission torsion spring 45 is less than the resistance received by the transmission seat 43, and the transmission seat 43 cannot be driven to rotate, so that the transmission ring 44 rotates relative to the transmission seat 43, and the transmission torsion spring 45 is torsion-prone; the rotation of the transmission ring 44 relative to the transmission seat 43 causes the auxiliary shifting drive mechanism 6 to switch from a disengaged state to an engaged state; then, the torque of the speed change mechanism 3 or the output housing 2 is transmitted to the transmission seat 43 through the auxiliary shifting drive mechanism 6; the transmission seat 43 is respectively subjected to the driving force of the transmission torsion spring 45 and the driving force of the auxiliary shifting drive mechanism 6. Under the action of the dual driving forces, it can promote the transmission seat 43 to overcome the resistance and rotate, thereby smoothly executing the shifting action; after the shifting is completed, the auxiliary shifting drive mechanism 6 switches to a disengaged state.

[0029] When the driving force of the transmission torsion spring 45 is less than the resistance of the transmission seat 43 and the transmission seat 43 cannot be driven to rotate, it is usually necessary to wait for the resistance of the transmission seat 43 to become smaller than the driving force of the transmission torsion spring 45, so as to drive the transmission seat 43 to rotate; if the resistance of the transmission seat 43 is always greater than the driving force of the transmission torsion spring 45, the gear shifting action cannot be performed, affecting the riding experience; in this case, in this embodiment, an auxiliary gear shifting drive mechanism 6 is added to provide additional driving force to promote the rotation of the transmission seat 43, so that the gear shifting action is performed quickly and smoothly, and the user experience is optimized.

[0030] Reference Figures 1 to 7 The main shift drive mechanism 5 adopts manual or electric operation, which belongs to external driving force; in this embodiment, the auxiliary shift drive mechanism 6 takes over the torque from the speed change mechanism 3 or the output housing 2, which belongs to internal driving force; that is, when the gear shift is blocked, the auxiliary shift drive mechanism 6 automatically forms an auxiliary torque transmission path acting on the transmission seat 43, and after the gear shift is completed, the auxiliary torque transmission path is automatically cut off.

[0031] Reference Figures 1 to 7 On the basis of the main shift drive mechanism 5, the auxiliary shift drive mechanism 6 is adopted in this embodiment, which can automatically provide torque from the transmission device itself to assist in driving the shift sleeve 42 to rotate when the gear shift is blocked, thereby promoting the smooth execution of the gear shift action and optimizing the user experience; the auxiliary shift drive mechanism 6 takes over the internal driving force of the gear shift device itself, does not require additional control, can greatly simplify the structure, reduce costs, and is convenient for layout.

[0032] Reference Figures 1 to 7In this embodiment, the auxiliary shift drive mechanism 6 includes a shift clutch assembly and a clutch control member; specifically, the shift clutch assembly in this embodiment is a ratchet pawl assembly, which includes a clutch inner ring 61, multiple clutch members 62, a clutch retaining ring 63, a clutch outer ring 64, a drive ring 65 and a flexible transmission member; wherein, the clutch inner ring 61 is linked with the transmission seat 43 in the circumferential direction; preferably, the clutch inner ring 61 and the transmission seat 43 are integrally formed, thereby simplifying the structure, reducing the number of parts and assembly procedures; in this embodiment, the auxiliary shift drive mechanism 6 takes over the torque from the speed change mechanism 3, thereby facilitating the arrangement; specifically, the speed change mechanism 3 includes a planetary carrier 31, and the drive ring 65 is fixed to the end of the planetary carrier 31 by bolts, thereby bearing the torque from the speed change mechanism; of course, in other optional embodiments, the drive ring 65 can also be connected to other rotating parts of the speed change mechanism 3, which is not limited here.

[0033] Reference Figures 1 to 7 , a flexible transmission part is used, so that the drive ring 65 and the clutch outer ring 64 include a transmission state and an overrunning state; when the clutch outer ring 64 encounters a large resistance and cannot rotate smoothly, the drive ring 65 and the flexible transmission part rotate together relative to the clutch outer ring 64 and enter the overrunning state, which plays a protective role and prevents damage to the mechanism.

[0034] Reference Figures 1 to 7 Specifically, the flexible transmission part includes a transmission clamping spring 66; the outer side wall of the transmission clamping spring 66 is provided with a plurality of transmission protrusions 661, and the drive ring 65 is provided with a transmission slot 651 that cooperates with the transmission protrusions 661; the inner side wall of the transmission clamping spring 66 is provided with a plurality of transmission teeth 662, and the outer side wall of the clutch outer ring 64 is provided with a transmission gear ring 641 that cooperates with the transmission teeth 662; when the transmission protrusion 661 is embedded in the transmission slot 651, the transmission clamping spring 66 rotates synchronously with the drive ring 65; when the transmission teeth 662 are embedded in the tooth grooves of the transmission gear ring 641, the transmission clamping spring 66 rotates synchronously with the clutch outer ring 64; in the overtaking state, the transmission clamping spring 66 is deformed, causing the transmission teeth 662 to slide relative to the transmission gear ring 641, thereby playing a protective role.

[0035] Reference Figures 1 to 7 Preferably, the number of transmission teeth 662 is smaller than the number of tooth grooves of the transmission gear ring 641; specifically, in this embodiment, the inner side wall of the transmission retaining spring 66 is provided with four transmission teeth 662 evenly distributed along the circumferential direction, and the transmission gear ring 641 is arranged on the entire outer circumferential surface of the clutch outer ring 64; a small number of transmission teeth 662 are used in conjunction with the full circle of the transmission gear ring 641, which is conducive to entering the overtaking state while ensuring torque transmission, and can quickly switch from the overtaking state to the transmission state.

[0036] Reference Figures 1 to 7The retaining spring usually acts as an axial limiter, but in this embodiment, the retaining spring is structurally improved to form a transmission retaining spring 66, which can be arranged in a small space to achieve flexible transmission and is easy to assemble.

[0037] Reference Figures 1 to 7 In this embodiment, the shift clutch assembly includes two clutch members 62. The two clutch members 62 are arranged in opposite directions and serve as a forward clutch member and a reverse clutch member respectively to match the forward rotation and reverse rotation of the transmission ring 44. When shifting, the main shift drive mechanism 5 controls the forward rotation or reverse rotation of the transmission ring 44, and the auxiliary shift drive mechanism is in an engaged state through the forward clutch member or the reverse clutch member.

[0038] Reference Figures 1 to 7 Preferably, in this embodiment, the clutch control member and the transmission ring 44 are linked in the circumferential direction to open or close the clutch member 62; when shifting, the main shift drive mechanism 5 directly controls the transmission ring 44 to rotate, and the transmission ring 44 then drives the clutch control member to rotate, which can realize the automatic intervention of the auxiliary shift drive mechanism 6, ensure consistency with the main shift drive mechanism 5, and simplify the structure.

[0039] Reference Figures 1 to 7 Preferably, in this embodiment, the clutch control component includes a limit ring 67 located between the clutch inner ring 61 and the clutch outer ring 64, and the limit ring 67 is provided with a plurality of release holes 671 arranged at intervals along the circumferential direction; when the gear shift is blocked, the main gear shift drive mechanism 5 controls the transmission ring 44 to rotate, and the transmission ring 44 then drives the limit ring 67 to rotate, opening the clutch member 62 through the release hole 671, so that the auxiliary gear shift drive mechanism 6 automatically switches to the engaged state, providing auxiliary driving force for the gear shift; after the gear shift is completed, the transmission seat 43 rotates into place, so that the clutch member 62 is closed by the limit ring 67, and the auxiliary gear shift drive mechanism 6 automatically switches to the disengaged state; preferably, the limit ring 67 is integrally formed on the end face of the transmission ring 44, so as to simplify the structure, reduce the number of parts, and facilitate layout; the position and length of the release hole 671 can be adjusted according to the gear position, and are not limited here.

[0040] Reference Figures 1 to 7, in the single-mechanism shifting driving condition, the transmission ring 44, the limiting ring 67, the transmission seat 43 and the clutch 62 rotate synchronously, and the limiting ring 67 keeps the clutch 62 in a closed state, and the auxiliary shifting driving mechanism 6 does not provide driving force; in the dual-mechanism shifting driving condition, the transmission ring 44 rotates relative to the transmission seat 43, and the limiting ring 67 rotates synchronously with the transmission ring 44, then the limiting ring 67 rotates relative to the clutch 62, so that the release hole 671 is opposite to the clutch 62, thereby opening the clutch 62, so that the auxiliary shifting driving mechanism 6 provides additional driving force to the transmission seat 43; after the transmission seat 43 rotates, it drives the shift sleeve 42 to rotate, thereby smoothly executing the shifting action; in this process, the transmission seat 43 rotates relative to the transmission ring 44, and the clutch 62 rotates synchronously with the transmission seat 43, then the clutch 62 rotates relative to the limiting ring 67, so after the shifting is completed, the clutch 62 rotates to be closed by the limiting ring 67.

Claims

1. A speed change device comprising a speed change mechanism, a shift actuator, a main shift drive mechanism, and an output housing; The shift actuator includes a shift sleeve, a transmission seat circumferentially linked to the shift sleeve, a transmission ring, and a transmission torsion spring disposed between the transmission seat and the transmission ring; Its characteristics are: The speed change device further includes an auxiliary shift drive mechanism, wherein the auxiliary shift drive mechanism includes an engaged state and a disengaged state; The speed change device includes a single-mechanism shift drive working condition and a dual-mechanism shift drive working condition; Single-mechanism shift drive working condition: The main shift drive mechanism controls the rotation of the transmission ring, and then drives the transmission seat to rotate through the transmission torsion spring; at this time, the auxiliary shift drive mechanism is in a disengaged state; Dual-mechanism shift drive working condition: the main shift drive mechanism controls the rotation of the transmission ring, and the driving force of the transmission torsion spring is less than the resistance of the transmission seat, so that the transmission ring rotates relative to the transmission seat, thereby switching the auxiliary shift drive mechanism from the disengaged state to the engaged state; then, the torque of the speed change mechanism or the output housing is transmitted to the transmission seat via the auxiliary shift drive mechanism; after the shift is completed, the auxiliary shift drive mechanism switches to the disengaged state.

2. The speed change device according to claim 1, characterized in that: The auxiliary shift drive mechanism includes a shift clutch assembly and a clutch control member; The shift clutch assembly includes a clutch inner ring, a plurality of clutch members, and a clutch outer ring; the clutch inner ring is linked to the transmission seat along the circumferential direction, and the clutch outer ring is used to receive torque from the speed change mechanism or the output housing; The clutch control member is used to open or close the clutch member, so that the auxiliary shift drive mechanism switches between an engaged state and a disengaged state.

3. The speed change device according to claim 2, characterized in that: The clutch inner ring and the transmission seat are integrally formed.

4. The speed change device according to claim 2, characterized in that: The plurality of clutch members include a forward clutch member and a reverse clutch member; In the dual-mechanism shift drive mode, the main shift drive mechanism controls the transmission ring to rotate forward or reverse, and the auxiliary shift drive mechanism is in an engaged state through the forward clutch or the reverse clutch.

5. The speed change device according to claim 2, characterized in that: The shift clutch assembly also includes a drive ring connected to the speed change mechanism or the output housing, and a flexible transmission member arranged between the drive ring and the clutch outer ring; through the flexible transmission member, the drive ring and the clutch outer ring include a transmission state and an overrunning state.

6. The speed change device according to claim 5, characterized in that: The flexible transmission part includes a transmission retaining spring; the outer side wall of the transmission retaining spring is provided with multiple transmission protrusions, and the drive ring is provided with a transmission retaining groove that cooperates with the transmission protrusions; the inner side wall of the transmission retaining spring is provided with multiple transmission teeth, and the outer side wall of the clutch outer ring is provided with a transmission gear ring that cooperates with the transmission teeth.

7. The speed change device according to claim 6, characterized in that: The number of the transmission teeth is smaller than the number of tooth grooves of the transmission gear ring.

8. The speed change device according to claim 2, characterized in that: The clutch control member is linked to the transmission ring along the circumferential direction to open or close the clutch member.

9. The speed change device according to claim 8, characterized in that: The clutch control component includes a limit ring located between the clutch inner ring and the clutch outer ring, and the limit ring is provided with a plurality of release holes arranged at intervals along the circumferential direction; when shifting, the clutch component is opened through the release holes; after the shifting is completed, the limit ring closes the clutch component.

10. The speed change device according to claim 1, characterized in that: The outer side wall of the transmission seat is provided with an annular cavity, and the two opposite inner side walls of the annular cavity are respectively provided with a first arc groove and a second arc groove; The transmission torsion spring is arranged in the annular cavity, and the two ends of the transmission torsion spring are respectively provided with a first blocking rod extending into the first arc groove and a second blocking rod extending into the second arc groove; The inner side wall of the transmission ring is respectively provided with a first boss for cooperating with the first gear lever, and a second boss for cooperating with the second gear lever; When the transmission ring rotates forward, the first boss drives the first shift lever to rotate, and the second shift lever contacts the inner end surface of the second arc groove under the action of elastic force, and drives the transmission seat to rotate forward; When the transmission ring rotates reversely, the second boss drives the second shift lever to rotate, and the first shift lever contacts the inner end surface of the first arc groove under the action of elastic force, and drives the transmission seat to reverse.

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