Differential feeding mechanism, sewing machine and control method

Abstract

According to the differential feeding mechanism, the sewing machine and the control method, the differential feeding mechanism comprises a lower differential tooth, a collar strip opening module and an upper differential tooth, and the lower differential tooth is used for conveying a collar strip; the collar strip opening module comprises two supporting wheels, and the two supporting wheels are arranged on the two opposite sides of the lower differential tooth and used for opening a collar strip. Moreover, the distance between the two supporting wheels can be actively adjusted, and the distance between the two supporting wheels is used for adjusting the opening distance of the collar strip; the upper differential teeth are arranged above the lower differential teeth in the vertical direction and used for conveying the body cloth, and the movement amount of the upper differential teeth can be actively adjusted and used for adjusting the feeding amount of the body cloth; when the motion amount of the upper differential teeth is adjusted, the distance between the two supporting wheels is actively adjusted. Therefore, on one hand, the sewing flatness of the round collar can be improved, and the product quality is effectively guaranteed; and on the other hand, the dependence on the operating skills of workers can be greatly reduced, the difficulty of the sewing process is simplified, meanwhile, the production efficiency is improved, and dual optimization of quality and productivity is achieved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field related to collar sewing, in particular to a differential feeding mechanism, a sewing machine and a control method. BACKGROUND

[0002] When sewing a collar, different positions of the collar have different requirements for the feeding position to ensure the flatness, fit and aesthetics of the overall collar.

[0003] In the existing sewing process, the feeding position control of collar sewing relies heavily on manual assistance. Since different parts of the collar (such as the front collar center and the shoulder line turning point) have different requirements for the feeding position, workers need to adjust the feeding rhythm of the body cloth and the stretching degree of the collar strip by hand. This operation method requires a high degree of skill for workers, not only increasing the difficulty of sewing, but also easily leading to a decline in product consistency due to human factors, affecting overall quality and production efficiency. SUMMARY

[0004] Therefore, it is necessary to provide a differential feeding mechanism, a sewing machine and a control method for solving the above technical problems.

[0005] A differential feeding mechanism is applied to a sewing machine for conveying a collar strip and a body cloth, the collar strip is sewn on the body cloth and forms a collar; the differential feeding mechanism comprises:

[0006] a lower differential tooth for conveying the collar strip;

[0007] a collar strip stretching module comprising two support wheels, the two support wheels are arranged on the two opposite sides of the lower differential tooth for stretching the collar strip, and the distance between the two support wheels can be actively adjusted to adjust the stretching distance of the collar strip;

[0008] an upper differential tooth arranged above the lower differential tooth in the vertical direction for conveying the body cloth, and the movement amount of the upper differential tooth can be actively adjusted to adjust the feeding amount of the body cloth;

[0009] wherein the distance between the two support wheels is actively adjusted when the movement amount of the upper differential tooth is adjusted.

[0010] It can be understood that by synchronously adjusting the stretching distance of the collar strip and the feeding amount of the body cloth, the collar strip can dynamically adapt to different states of the body cloth. This self-adaptive adjustment mechanism can not only significantly improve the flatness of collar sewing and effectively ensure product quality, but also greatly reduce the dependence on worker operation skills, simplifying the sewing process difficulty, improving production efficiency, and achieving double optimization of quality and capacity.

[0011] In one of the embodiments, the movement amount of the upper differential tooth and the distance between the two supporting wheels are simultaneously reduced.

[0012] It can be understood that, by simultaneously reducing the movement amount of the upper differential tooth and the distance between the two supporting wheels, the collar sewn by the sewing machine can achieve the best sewing effect at the position where it needs to be straightened and stretched.

[0013] In one of the embodiments, the movement amount of the upper differential tooth and the distance between the two supporting wheels are simultaneously increased.

[0014] It can be understood that, by simultaneously increasing the movement amount of the upper differential tooth and the distance between the two supporting wheels, the large body cloth can achieve the best sewing effect when it is shrunk.

[0015] In one of the embodiments, the two supporting wheels are arranged on the opposite sides of the collar strip in the conveying direction of the collar strip.

[0016] The two supporting wheels are arranged as a first supporting wheel and a second supporting wheel, the first supporting wheel is fixedly arranged, and the second supporting wheel can actively move relative to the lower differential tooth in the conveying direction of the collar strip.

[0017] It can be understood that, by adopting the structure that the first supporting wheel is fixed and the second supporting wheel is movable, the stretching distance of the collar strip can be controlled, so that the collar strip stretching module can achieve dynamic control of the stretching distance of the collar strip by adjusting the displacement amount of the second supporting wheel. This not only makes the operation simple and intuitive, but also ensures that the collar strip and the large body cloth always maintain the best matching state at different sewing stages, thereby effectively improving the flatness and process stability of the collar sewing.

[0018] In one of the embodiments, the collar strip stretching module further comprises a driving member and a transmission assembly, the driving member is in transmission connection with the second supporting wheel through the transmission assembly, and is used to provide power for the movement of the second supporting wheel.

[0019] When the driving member drives the second supporting wheel to move, the moving stroke can be adjusted.

[0020] It can be understood that, by adopting the driving member in cooperation with the transmission assembly to control the movement of the second supporting wheel, the arrangement of the structure required for the movement adjustment of the second supporting wheel in the sewing machine can be facilitated, and the control of the moving stroke of the second supporting wheel when it moves can be facilitated.

[0021] In one of the embodiments, the differential feeding mechanism further comprises a control panel, the control panel can control the multiple conveyance of the large body cloth by the upper differential tooth, and the control panel can adjust the feeding amount of the large body cloth each time it is conveyed.

[0022] The control panel is electrically connected with the driving member, and is used for controlling the working of the driving member.

[0023] In one of the embodiments, the control panel has an input module, which can be inputted with a first control signal and a second control signal.

[0024] The first control signal is used for setting the number of transmissions of the upper differential tooth and the feeding amount in each transmission.

[0025] The second control signal is used for setting the moving stroke of the second supporting wheel.

[0026] It can be understood that, by manually inputting different control signals through the input module, the sewing machine can intelligently identify and automatically adapt to the sewing process requirements of different types of round collars, and realize optimal sewing control. This programmable input control system can significantly improve the process adaptability of the sewing machine, so that the sewing machine can meet the standardized production of basic round collars, and can also quickly adapt to the sewing requirements of special collar types such as deep U collars and boat collars through parameter adjustment, effectively expanding the processing range and application scenarios of the sewing machine, and providing technical support for flexible production of multiple varieties and small batches.

[0027] The application also provides a sewing machine comprising the differential feeding mechanism.

[0028] The application also provides a control method, which comprises the following steps:

[0029] providing the differential feeding mechanism;

[0030] controlling the upper differential tooth to transmit the body cloth, and controlling the lower differential tooth to transmit the collar strip;

[0031] adjusting the movement amount of the upper differential tooth and the distance between the two supporting wheels.

[0032] In one of the embodiments, the step of adjusting the movement amount of the upper differential tooth and the distance between the two supporting wheels comprises:

[0033] The movement amount of the upper differential tooth and the distance between the two supporting wheels are both reduced; or the movement amount of the upper differential tooth and the distance between the two supporting wheels are both increased.

[0034] Due to the application of the above technical solutions, the application has the following advantages compared with the prior art:

[0035] The differential feeding mechanism, sewing machine and control method claimed in the application can dynamically adapt the collar strip to the different states of the body fabric by synchronously adjusting the collar strip opening distance and the body fabric feeding amount, which can significantly improve the flatness of the round collar sewing, effectively guarantee the product quality, and greatly reduce the dependence on the operation skills of workers, thereby simplifying the sewing process difficulty, improving the production efficiency, and realizing the dual optimization of quality and capacity. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0037] Figure 1 The structure schematic diagram of the sewing machine provided by the present application.

[0038] Figure 2 The structure schematic diagram of the sewing machine provided by the present application. Figure 1 The enlarged view of A part in the figure.

[0039] Figure 3 The structure schematic diagram of the sewing machine provided by the present application. The structure schematic diagram of the sewing machine provided by the present application.

[0040] The structure schematic diagram of the sewing machine provided by the present application. Figure 4 The enlarged view of B part in the figure. Figure 3 The flow chart of the control method provided by the present application.

[0041] Figure 5 The structure schematic diagram of the sewing machine provided by the present application.

[0042] Figure 6 The structure schematic diagram of the sewing machine provided by the present application.

[0043] Reference signs: 100, sewing machine; 10, lower differential tooth; 20, collar strip opening module; 21, support wheel; 211, first support wheel; 212, second support wheel; 2121, mounting plate; 2122, tooth pressure plate; 22, driving piece; 23, transmission assembly; 231, synchronous belt; 30, upper differential tooth; 40, needle plate; 50, sewing table; 60, presser foot. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present application will be clearly and completely described with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0045] It should be noted that when an element is referred to as being "arranged on" another element, it can be directly arranged on the other element or there can be a middle element. When an element is referred to as being "arranged on" another element, it can be directly arranged on the other element or there can be a middle element. When an element is referred to as being "fixed on" another element, it can be directly fixed on the other element or there can be a middle element.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terminology used in the description of the present application only for the purpose of describing a specific embodiment and is not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more related items listed.

[0047] The differential feeding mechanism claimed in the present application is applied to a sewing machine 100 for conveying a collar (not shown in the figure) and a body cloth (not shown in the figure), the collar being sewn to the body cloth to form a round collar; here, the collar is annular and has a certain elastic extension.

[0048] As shown in Figure 1 , Figure 2 The differential feeding mechanism provided by the present application includes a lower differential tooth 10, a collar opening module 20 and an upper differential tooth 30, the lower differential tooth 10 being used for conveying the collar; the collar opening module 20 includes two supporting wheels 21 arranged on two opposite sides of the lower differential tooth 10 for opening the collar; and the distance between the two supporting wheels 21 can be actively adjusted for adjusting the opening distance of the collar; the upper differential tooth 30 is arranged above the lower differential tooth 10 in the vertical direction Z for conveying the body cloth, and the movement amount of the upper differential tooth 30 can be actively adjusted for adjusting the feeding amount of the body cloth; wherein when the movement amount of the upper differential tooth 30 is adjusted, the distance between the two supporting wheels 21 is actively adjusted. Here, the feeding amount of the body cloth refers to the conveying length of the body cloth when it is conveyed by the upper differential tooth 30. It should be noted that the other structural components of the differential feeding mechanism and the working principle of how the lower differential tooth 10 and the upper differential tooth 30 realize the respective conveying of the collar and the body cloth can adopt the conventional manner of the prior art, which will not be described here.

[0049] From the above, the differential feeding mechanism of the present application can dynamically adapt the collar to the different states of the body fabric by synchronously adjusting the collar opening distance and the body fabric feeding amount, which can significantly improve the flatness of the round collar sewing and effectively ensure product quality, and can also greatly reduce the dependence on worker operation skills, thereby simplifying the sewing process difficulty, improving production efficiency, and achieving double optimization of quality and capacity.

[0050] It should be noted that since the distance between the two support wheels 21 can be actively adjusted, when the collar is fitted to the two support wheels 21 and the lower differential tooth 10, and the round collar obtained by sewing is removed from the two support wheels 21, the distance between the two support wheels 21 can be first controlled to be the smallest, so that the collar can be easily disassembled on the two support wheels 21.

[0051] When the position of the round collar sewn by the sewing machine 100 needs to be straightened, the differential feeding mechanism can control the two support wheels 21 to reduce the opening distance of the collar, thereby reducing the stretching ratio of the collar, and control the upper differential tooth 30 to reduce the movement amount, thereby reducing the feeding amount of the body fabric, so that the round collar sewn by the sewing machine 100 can achieve the best sewing effect at the position that needs to be straightened. When the body fabric is wrinkled, the differential feeding mechanism can control the two support wheels 21 to increase the opening distance of the collar, thereby increasing the stretching ratio of the collar, and control the upper differential tooth 30 to increase the movement amount, thereby increasing the feeding amount of the body fabric, so that the round collar sewn by the sewing machine 100 can achieve the best sewing effect at the position that needs to be straightened, so that the sewing machine 100 can achieve the best sewing effect when the body fabric in the wrinkled state is sewn with the collar according to the position of the round collar.

[0052] As shown in FIG. 6, the two support wheels 21 are arranged on the same axis, and the lower differential tooth 30 is arranged between the two support wheels 21. Figure 2As shown in the drawings, in an embodiment, two supporting wheels 21 are arranged on two opposite sides of the lower differential tooth 10 in the collar conveying direction X; wherein the two supporting wheels 21 are defined as a first supporting wheel 211 and a second supporting wheel 212, the first supporting wheel 211 is fixedly arranged, and the second supporting wheel 212 is capable of being actively moved relative to the lower differential tooth 10 in the collar conveying direction X. That is to say, the collar stretching module 20 of this embodiment adopts the adjusting structure of the fixed first supporting wheel 211 and the movable second supporting wheel 212 to control the stretching distance of the collar, so that the collar stretching module 20 can realize dynamic control of the stretching distance of the collar by adjusting the displacement amount of the second supporting wheel 212, which not only is simple and intuitive to operate, but also can ensure that the collar and the body fabric are always in the best matching state at different sewing stages, thereby effectively improving the flatness and process stability of the round collar sewing. Here, the first supporting wheel 211 is arranged on the outer side of the lower differential tooth 10, and the second supporting wheel 212 is arranged on the inner side of the lower differential tooth 10; and both the first supporting wheel 211 and the second supporting wheel 212 are capable of free rolling, so that the friction between the first supporting wheel 211 and the second supporting wheel 212 and the collar is rolling friction when the lower differential tooth 10 conveys the collar, which can reduce the friction resistance of the first supporting wheel 211 and the second supporting wheel 212 on the lower differential tooth 10 when conveying the collar.

[0053] As shown in the drawings, Figure 3 , Figure 4 As shown in the drawings, in an embodiment, the collar stretching module 20 further comprises a driving member 22 and a transmission assembly 23, the driving member 22 is in transmission connection with the second supporting wheel 212 through the transmission assembly 23, and is used for providing power for the movement of the second supporting wheel 212; and the movement stroke of the second supporting wheel 212 driven by the driving member 22 to move can be adjusted. That is to say, this embodiment adopts the mode of the driving member 22 cooperating with the transmission assembly 23 to control the movement of the second supporting wheel 212, which can facilitate the arrangement of the structure required for the movement adjustment of the second supporting wheel 212 in the sewing machine 100, and facilitate the control of the movement stroke of the second supporting wheel 212 when moving.

[0054] In this embodiment, the second supporting wheel 212 is rotatably installed on the mounting plate 2121 through a connecting shaft (not shown), the driving member 22 is configured as a motor, the transmission assembly 23 is configured as a synchronous belt transmission structure, and the mounting plate 2121 is installed on the synchronous belt 231 of the synchronous belt transmission structure through the toothed pressure plate 2122, so that the motor can drive the second supporting wheel 212 to move in the collar conveying direction X through the synchronous belt 231. It can be understood that in other embodiments, the driving member 22 can also be configured as a rotary air cylinder or a rudder; or the driving member 22 is configured as a hydraulic cylinder or a telescopic motor, and the transmission assembly 23 is configured as a connecting plate connecting the mounting plate 2121 and the telescopic part of the driving member 22, which will not be described here.

[0055] AsFigure 6 As shown, in an embodiment, the differential feeding mechanism further comprises a control panel (not shown in the figure), which is capable of controlling the upper differential tooth 30 to convey the body fabric multiple times, and is capable of adjusting the feeding amount of each time of conveying the body fabric. That is, the differential feeding mechanism of this embodiment realizes the conveying of the collar and the body fabric by adopting a multi-segment conveying mode to meet the use requirements of sewing a round collar. Here, the control panel controls the upper differential tooth 30 to convey the body fabric by adopting a six-segment mode, wherein each segment of conveying the body fabric by the upper differential tooth 30 corresponds to different positions of the round collar to meet the requirement that different positions of the round collar have different capacities. It can be understood that in other embodiments, the control panel can also control the upper differential tooth 30 to convey the body fabric by adopting a five-segment, seven-segment, etc. mode, which can be used and improved according to the sewing process requirements of different types of round collars. It should be noted that the sewing machine 100 needs to be sewn in multiple segments according to different positions of the round collar during the sewing of the round collar, which is a conventional way of the existing garment round collar sewing process, which will not be expanded here. Here, the control panel is electrically connected with the driving member 22 for controlling the working of the driving member 22.

[0056] In this embodiment, the control panel has an input module, which can be inputted with a first control signal and a second control signal; the first control signal is used to set the conveying times of the upper differential tooth 30, the feeding amount of each time of conveying; and the second control signal is used to set the moving stroke of the second supporting wheel 212 when moving, and specifically controls the working of the driving member 22. That is, the differential feeding mechanism of this embodiment can manually input different control signals through the input module, so that the sewing machine 100 can intelligently recognize and automatically adapt to the sewing process requirements of different types of round collars to realize the optimal sewing control. This programmable input control system can significantly improve the process adaptability of the sewing machine 100, so that the sewing machine 100 can meet the standardized production of basic round collars, and can also quickly adapt to the sewing requirements of special collar types such as deep U collar and boat collar through parameter adjustment, effectively expanding the processing range and application scene of the sewing machine 100, and providing technical support for flexible production of multiple varieties and small batches.

[0057] Here, the first control signal specifically refers to the corresponding parameters of the conveying times of the upper differential tooth 30 and the feeding amount of each time of conveying, so that the upper differential tooth 30 can convey the body fabric under the above parameters when the differential feeding mechanism works; similarly, the second control signal specifically refers to the parameter of the moving stroke of the second supporting wheel 212 when moving, so that the differential feeding mechanism can control the displacement of the second supporting wheel 212 according to the conveying requirements of the body fabric by the upper differential tooth 30.

[0058] As Figure 1 , Figure 3As shown, the present application also provides a sewing machine 100, including the differential feeding mechanism described above. If necessary, the other structural components of the sewing machine 100 and the working method of sewing the collar strip onto the body fabric can adopt conventional methods of the prior art, which will not be elaborated here.

[0059] like Figure 5 As shown, the present application also provides a control method, which includes the following steps:

[0060] Providing the differential feeding mechanism described above;

[0061] Control the upper differential gear 30 to deliver the body fabric, and control the lower differential gear 10 to deliver the collar strip;

[0062] Adjust the movement of the upper differential gear 30 and the distance between the two support wheels 21.

[0063] Among them, the above step of "adjusting the movement amount of the upper differential tooth 30 and the distance between the two support wheels" includes: the movement amount of the upper differential tooth 30 and the distance between the two support wheels 21 are both reduced; or, the movement amount of the upper differential tooth 30 and the distance between the two support wheels 21 are both increased.

[0064] like Figure 6 As shown, the sewing machine 100 of the present application divides the crew neck into six sections, each corresponding to an optimal feed rate for the main body fabric and a desired collar extension distance. Furthermore, the movement of the upper differential gear 30 and the displacement of the second support wheel 212 are displayed on the control panel. When sewing a crew neck, the collar strip contacts the needle plate 40 and the sewing table 50, while the main body fabric contacts the presser foot 60 and the upper differential gear 30.

[0065] When the collar finds the bone position, the second support wheel 212 moves to the set position.

[0066] When the sewing machine 100 is sewing the first section of a crew neck, the driver 22 operates, causing the second support wheel 212 to move to a predetermined position. Simultaneously, the differential motor (not shown) operates, adjusting the movement of the upper differential teeth 30 to the predetermined first differential setting position. When the sewing machine 100 is sewing the second, third, fourth, fifth, and sixth sections of a crew neck, the second support wheel 212 moves to a predetermined position, and the movement of the upper differential teeth 30 is adjusted to the corresponding differential setting position, following the control method used for the first section.

[0067] During the sewing process, if the process requires the second section of the crew neck to be stretched straight, the differential feed mechanism can reduce the distance between the two support wheels 21, thereby reducing the movement of the upper differential teeth 30. When sewing is completed, the collar strip and the main body fabric of the crew neck are both free. The collar strip can accommodate less main body fabric per unit distance, which will cause the crew neck fabric to stretch more straight.

[0068] In the sewing process, if the third section of the body fabric is required to be shrunk, the differential feeding mechanism can increase the movement of the upper differential tooth 30 by increasing the distance between the two supporting wheels 21. When the collar strip and the body fabric are both in a free state after the sewing is completed, the body fabric contained in the unit distance of the collar strip will increase, so that the fabric of the collar tends to shrink more.

[0069] The technical features of the above embodiments can be combined in any manner. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combinations of the technical features do not contradict, they should be considered as falling within the scope of the present disclosure.

[0070] Those skilled in the art should recognize that the above embodiments are used to illustrate the present application, but not as a limitation of the present application, and as long as the changes and variations of the above embodiments are within the spirit and scope of the present application, they fall within the scope of the present application.

Claims

1. A differential feeding mechanism, used in a sewing machine (1000), for conveying a collar strip and a body fabric, wherein the collar strip is sewn to the body fabric to form a round collar; characterized in that: The differential feeding mechanism includes: A lower differential tooth (10) for transmitting the collar strip; A collar strip stretching module (20) comprises two support wheels (21), the two support wheels (21) being arranged on two opposite sides of the lower differential tooth (10) and being used to stretch the collar strip, and the spacing between the two support wheels (21) being actively adjustable to adjust the stretching distance of the collar strip; An upper differential tooth (30) is arranged above the lower differential tooth (10) in the vertical direction and is used to convey the body fabric, and the movement amount of the upper differential tooth (30) can be actively adjusted to adjust the feeding amount of the body fabric; When the upper differential tooth (30) adjusts the amount of movement, the distance between the two support wheels (21) is actively adjusted.

2. The differential feeding mechanism according to claim 1, characterized in that: The movement amount of the upper differential tooth (30) and the distance between the two support wheels (21) are reduced simultaneously.

3. The differential feeding mechanism according to claim 1, characterized in that: The movement amount of the upper differential tooth (30) and the distance between the two support wheels (21) increase simultaneously.

4. The differential feeding mechanism according to claim 1, characterized in that: The two support wheels (21) are arranged on two opposite sides of the lower differential tooth (10) in the collar strip transmission direction; The two support wheels (21) are configured as a first support wheel (211) and a second support wheel (212), wherein the first support wheel (211) is fixedly arranged, and the second support wheel (212) can actively move relative to the lower differential tooth (10) in the collar strip transmission direction.

5. The differential feeding mechanism according to claim 4, characterized in that: The collar strip stretching module (20) further comprises a driving member (22) and a transmission assembly (23), wherein the driving member (22) is connected to the second support wheel (212) via the transmission assembly (23) for providing power for the movement of the second support wheel (212); When the driving member (22) drives the second supporting wheel (212) to move, the movement stroke can be adjusted.

6. The differential feeding mechanism according to claim 5, characterized in that: The differential feeding mechanism further comprises a control panel, wherein the control panel is capable of controlling the upper differential teeth (30) to transmit the body fabric multiple times, and the control panel is capable of adjusting the feeding amount each time the body fabric is transmitted; The control panel is electrically connected to the driving member (22) and is used to control the operation of the driving member (22).

7. The differential feeding mechanism according to claim 6, characterized in that: The control panel has an input module, and the input module can be input with a first control signal and a second control signal; The first control signal is used to set the number of transmissions of the upper differential tooth (30) and the feeding amount of each transmission; The second control signal is used to set the movement stroke of the second support wheel (212) when it moves.

8. A sewing machine, characterized in that: A differential feeding mechanism comprising any one of claims 1 to 7.

9. A control method, characterized in that: The control method includes the following steps: Providing a differential feeding mechanism according to any one of claims 1 to 7; Controlling the upper differential teeth (30) to transmit the main body fabric, and controlling the lower differential teeth (10) to transmit the collar strip; Adjust the movement of the upper differential gear (30) and the distance between the two support wheels (21).

10. The control method according to claim 9, characterized in that: The step of "adjusting the movement of the upper differential gear (30) and the spacing between the two support wheels (21)" includes: The movement amount of the upper differential tooth (30) and the distance between the two support wheels (21) are both reduced; or, the movement amount of the upper differential tooth (30) and the distance between the two support wheels (21) are both increased.

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