A central shaft transmission and a centrally located motor

Abstract

The utility model belongs to the technical field of transmission, especially relates to a middle axle transmission and middle -placed motor. The middle axle transmission and middle -placed motor of the present application, through torque sensor collection through the torque of middle axle, the positive rotation of middle axle and drive the gear shifting mechanism to shift when drive arrangement drives the gear shifting mechanism to shift in below or equal to the preset value, can avoid the larger bite of the ratchet and gear locking groove when shifting, and execute the gear shifting at the smaller time, make the normal rotation of rotation control spare, to improve the gear shifting success rate and the smoothness.

Description

Technical Field

[0001] This utility model belongs to the field of transmission technology, and specifically relates to a central shaft transmission and a centrally mounted motor. Background Technology

[0002] Chinese patent document CN119617107A discloses a gear shifting device and a transmission, including a bushing with several mounting holes, one end of which has a mounting groove; several shift gears, which are rotatably mounted on the bushing and correspond to the positions of ratchet pawls; the inner rings of the shift gears are all provided with circumferential internal tooth grooves, which are arc-shaped tooth grooves; the number of ratchet pawls is equal to the total number of shift gears, one end of which has a protrusion and the other end has a sliding part, and the middle part of the ratchet rotatably mounts in the mounting groove; the shift gears include shift gears M for meshing with the input gear and shift gears N for meshing with the output gear, the total number of shift gears M and shift gears N is equal to the number of available gears plus one; each shift gear M... The tip circle diameter increases in the direction of power input, while the tip circle diameter of each gear N decreases in the direction of power input. On the bushing, the pawl corresponding to gear M and the pawl corresponding to gear N are arranged in opposite directions. The spindle has a gear drive section on its outer wall along the axial direction. The gear drive section includes several first drive sections and second and third drive sections located at both ends of the first drive sections. Adjacent first drive sections are evenly distributed at an angle along the circumference of the spindle. The total number of first, second, and third drive sections matches the number of gears. An elastic element is provided between the bottom of the pawl protrusion and the mounting groove to spring up the end and slide the pawl into the rotation path of the gear drive section.

[0003] When the spindle rotates, the pawl slides into the corresponding gear drive unit, and the protrusion of the pawl pops up and engages with the corresponding internal tooth groove; when the pawl slides into the outer wall of the spindle, the protrusion disengages from the internal tooth groove.

[0004] During the upshifting process, starting from first gear, as the pawl corresponding to the third drive unit slides within the third drive unit, the shift gear M engages with its corresponding pawl one by one in the direction away from the power input; as the pawl corresponding to the second drive unit slides within the second drive unit, the shift gear N engages with its corresponding pawl one by one in the direction away from the power input, thereby achieving a gradual increase in the speed ratio of each gear during upshifting.

[0005] Although shifting can be made smoother and riding more comfortable by engaging the next gear and disengaging the previous gear, as well as by improving the ratchet mechanism, situations where shifting is impossible can still occur during uphill riding or high-speed riding.

[0006] Therefore, existing technologies need to be improved and developed. Utility Model Content

[0007] The purpose of this application is to provide a central shaft transmission and a centrally mounted motor to improve shift success rate and smoothness.

[0008] This application provides a mid-shaft transmission, comprising:

[0009] The center axle is rotatably supported on the frame, and torque is input from the center axle;

[0010] The secondary shaft is hollow and parallel to the central shaft;

[0011] The transmission mechanism is connected to the central shaft and the secondary shaft respectively, and has at least two transmission ratios;

[0012] A drive unit, connected to the shifting mechanism, is located on the outside of the secondary shaft;

[0013] A shifting mechanism, linked to the transmission mechanism, is used to change the transmission ratio of the transmission mechanism;

[0014] The output component, fixed to the transmission mechanism, outputs torque;

[0015] A torque sensor detects the torque passing through the central shaft. When the central shaft rotates in the positive direction and the torque is lower than or equal to a preset value, the drive device drives the shifting mechanism to perform a shift.

[0016] Furthermore, the preset value is 10 Nm.

[0017] Furthermore, the gear shift is performed when the preset value is 0 Nm.

[0018] Furthermore, the gear shift is immediately performed when the central axis rotates in the opposite direction.

[0019] Furthermore, the torque sensor includes a force-sensitive element, a first circuit module connected to the force-sensitive element, and a second circuit module wirelessly connected to the first circuit module. The force-sensitive element is disposed on the secondary shaft, and the first circuit module rotates synchronously with the secondary shaft.

[0020] Furthermore, the shifting mechanism includes at least two pawls, a reset member, and a rotation control member. A groove is provided on the secondary shaft, and the pawl is rotatably installed in the groove. One end of the reset member abuts against the secondary shaft, and the other end of the reset member abuts against the pawl. A control groove is provided on the outer peripheral surface of the rotation control member, and the pawl is located on the outside of the rotation control member.

[0021] When the rotation angle between the rotary control component and the countershaft deflects, one end of the pawl falls into the control groove, fixing the gear of the shifting mechanism to the countershaft to change the transmission ratio.

[0022] Furthermore, the rotation control component is disposed on the inner side of the sub-shaft, and the drive device is disposed on the outer side of the rotation control component.

[0023] Furthermore, the control groove is at least two spirally arranged through grooves, which are opened along the circumference of the rotation control member, and adjacent through grooves are not connected.

[0024] Furthermore, the torque passing through the central axle includes the torque generated by the rider's pedaling.

[0025] This application also provides a mid-drive motor, including the aforementioned mid-shaft gearbox, and further including an assist motor and an assist motor reduction mechanism, wherein the assist motor is connected to the transmission mechanism through the assist motor reduction mechanism.

[0026] Furthermore, the torque passing through the central axis includes the torque generated by the rider pedaling and the torque generated by the assist motor.

[0027] As can be seen from the above, the central shaft gearbox and centrally mounted motor of this application collect the torque passing through the central shaft through a torque sensor. When the central shaft rotates in the forward direction and the torque is lower than or equal to a preset value, the drive device drives the shifting mechanism to shift gears. This can avoid shifting when there is a large biting force between the pawl and the locking groove of the gear, and instead perform shifting when the force is small, so that the rotation control component can rotate normally, thereby improving the success rate and smoothness of shifting.

[0028] Other features and advantages of this application will be set forth in the following description and will be apparent in part from the description or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings. Attached Figure Description

[0029] Figure 1 This is a perspective view of the shaft transmission in this application.

[0030] Figure 2 This is a perspective view of the shaft transmission (with housing, output components, and crankshaft hidden) in this application.

[0031] Figure 3 for Figure 2 Top view.

[0032] Figure 4 for Figure 3 Cross-sectional view.

[0033] Figure 5A schematic diagram of the assembly of the countershaft and shifting mechanism.

[0034] Figure 6 This is a schematic diagram of the gear shifting process of the gear shifting mechanism.

[0035] Figure 7 This is a cross-sectional view of the gear shifting process of the gear shifting mechanism.

[0036] Figure 8 This is a 3D view of the rotation control component.

[0037] Figure 9 This is a schematic diagram of a speed mixing mechanism.

[0038] Figure 10 This is a 3D view of the torque sensor.

[0039] Figure 11 This is an exploded view of the torque sensor.

[0040] Figure 12 This is a schematic diagram of the crank angle.

[0041] Figure 13 A graph of the torque collected by the torque sensor.

[0042] Figure 14 This is a schematic diagram of the structure of the motor in this application.

[0043] Label Explanation:

[0044] 1-Outer shell,

[0045] 2-Central axis,

[0046] 3-Secondary shaft, 31-Groove,

[0047] 4-Transmission mechanism, 41-First gear set, 411-First driving gear, 412-First driven gear, 42-Second gear set, 421-Second driving gear, 4211-Locking groove, 422-Second driven gear

[0048] 5-Shifting mechanism, 51-Pawl, 52-Reset component, 53-Rotation control component, 531-Control slot,

[0049] 6-Drive unit,

[0050] 7-Speed ​​mixing mechanism, 71-First ring gear, 72-First sun gear, 73-Planet carrier, 74-Multi-planetary gear, 741-Double planetary gear, 7411-First planetary gear, 7412-Second planetary gear, 75-Second sun gear, 76-Second ring gear

[0051] 8-Input component, 81-Left crank, 82-Right crank

[0052] 9-Output assembly, 91-Transmission sleeve, 92-Output component, 93-One-way clutch,

[0053] 10-Assist motor,

[0054] 11-Assisted motor reduction mechanism,

[0055] 12-Torque sensor, 121-Force-sensitive element, 122-First circuit module, 123-Second circuit module, 124-First housing, 125-Second housing, 126-Connecting block. Detailed Implementation

[0056] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0057] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0058] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0059] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0060] The central shaft transmission of this application is fixedly installed at the bottom center of the vehicle frame. The central shaft transmission includes a housing 1, a central shaft 2, a countershaft 3, a transmission mechanism 4, a drive unit 6, a shifting mechanism 5, and an output component 92. The housing 1 is fixed to the frame, and the countershaft 3 is rotatably supported within the housing 1. Except for the exposed output component 92, all other parts are concealed within the housing 1. Both ends of the central shaft 2 extend from the housing 1 and are rotatably supported on the frame. Input components 8 are fixedly connected to both ends of the central shaft 2. The input components 8 include a left... Crank 81 and right crank 82 are connected to the pedals by rotating the cranks. The rider transmits the torque generated by pedaling to the bottom bracket 2, and then from the bottom bracket 2 to the transmission mechanism 4. The shift mechanism 5 is linked with the transmission mechanism 4. The transmission mechanism 4 is used to change the gear ratio and output speed. Different gears are switched by changing the meshing relationship of different gears. The output component 92 is fixed on the transmission mechanism 4 and is used to output torque. The output component 92 then inputs the torque to the flywheel through chain drive or belt drive, which drives the rear wheel of the vehicle to rotate.

[0061] This device can be used on bicycles, folding bicycles, ebikes, electric-assisted bicycles, electric vehicles, electric motorcycles, electric cargo vehicles, tricycles, scooters, electric scooters, and other vehicles.

[0062] Figure 1 This is a perspective view of the shaft transmission in this application. Figure 2 This is a perspective view of the shaft transmission (housing 1, output component 92, and crank are hidden) in this application. Figure 3 for Figure 2 Top view. Figure 4 for Figure 3The cross-sectional view shows the transmission mechanism 4, which includes a first gear set 41 and a second gear set 42. The first gear set 41 includes a first driving gear 411 and a first driven gear 412 that mesh with each other. The first driving gear 411 is fixed to the central shaft 2, and the first driven gear 412 is fixed to the countershaft 3. The first driving gear 411 is driven to rotate by the central shaft 2, which in turn drives the first driven gear 412 to rotate the countershaft 3. In this embodiment, the number of teeth of the first driving gear 411 is greater than the number of teeth of the first driven gear 412. Therefore, the transmission ratio of the first gear set 41 is less than 1, which is a speed-increasing transmission.

[0063] The rotation of the countershaft 3 is transmitted to the second gear set 42, which includes a second driving gear 421 and a second driven gear 422 that mesh with each other. The second driving gear 421 is movably connected to the countershaft 3, and the second driven gear 422 is fixedly connected to a transmission sleeve 91, which is movably connected to the central shaft 2. The second driving gear 421 is fixed or movable relative to the countershaft 3 through a shifting mechanism 5 to perform gear shifting. The transmission sleeve 91 and the output component 92 are collectively referred to as the output assembly 9.

[0064] In this embodiment, the second gear set 42 is provided with seven second driving gears 421 and seven second driven gears 422. Figure 4 As can be seen, the number of teeth on the second driving gear 421 decreases progressively from left to right, while the number of teeth on the second driven gear 422 increases progressively from left to right. Therefore, the second gear set 42 could be either a speed-increasing or speed-reducing transmission. This central shaft transmission has seven gears.

[0065] In order to achieve gear shifting, a gear shifting mechanism 5 is set up, which can fix one of the six second drive gears 421 to the countershaft 3. Figure 5 A schematic diagram of the assembly of the countershaft 3 and the shifting mechanism 5. Figure 6 This is a schematic diagram of the shifting process of the shifting mechanism 5. The shifting mechanism 5 includes at least two pawls 51, a reset member 52, and a rotation control member 53. A groove 31 is formed along the circumference of the countershaft 3, and a rotating shaft is installed in the groove 31. At least two pawls 51 are arranged in a row along the axial direction of the countershaft 3 and are rotatably installed in the groove 31 after being mounted on the rotating shaft. The outer diameter of the rotation control member 53 is smaller than the outer diameter of the countershaft 3. The rotation control member 53 is hollow, and a control groove 531 is provided on the outer circumferential surface of the rotation control member 53. The pawls 51 are located on the outside of the rotation control member 53. One end of the reset member 52 abuts against the countershaft 3, and the other end of the reset member 52 abuts against the pawl 51. The reset member 52 presses down one end of the pawl 51, keeping it abutting against the outer circumferential surface of the rotation control member 53. It should be noted that the rotation control member 53 is not stationary; it rotates synchronously with the countershaft 3.

[0066] When the rotation angle between the rotation control component 53 and the secondary shaft 3 deviates, such as Figure 7 As shown, one end of the pawl 51 falls into the control groove 531, and the other end of the pawl 51 springs up and gets into the locking groove 4211 of the second drive gear 421, so that the second drive gear 421 of the shift mechanism 5 is fixed to the countershaft 3 to change the transmission ratio.

[0067] In this embodiment, as Figure 8 As shown, the control groove 531 provided on the outer peripheral surface of the rotary control component 53 consists of at least two spirally arranged through grooves. The cross-section of the through groove is rectangular, and the length and width of the cross-section are adapted to the length and width of the pawl 51, respectively. The through grooves are opened along the circumference of the rotary control component 53, and adjacent through grooves are not connected. When one end of the pawl 51 falls into the control groove 531, the groove wall will restrict the axial movement of one end of the pawl 51, preventing the force of the gear of the transmission mechanism 4 on the pawl 51 from causing the other end of the pawl 51 to disengage from the locking groove 4211 of the second drive gear 421, ensuring that there is no gear skipping and guaranteeing the accuracy of gear shifting.

[0068] In this embodiment, six pawls 51 are provided. The second driving gear 421 with the fewest teeth is fixed to the countershaft 3. A one-way clutch 93 is provided between the second driven gear 422 with the largest number of teeth and the transmission sleeve 91. This design can save the need to set up a pawl 51 to control the second driving gear 421 with the fewest teeth. The principle is as follows: when none of the pawls 51 fall into the control groove 531 of the rotation control member 53, the one-way clutch 93 engages, and the second driving gear 421 with the fewest teeth meshes with the second driven gear 422 with the largest number of teeth for transmission. When one of the pawls 51 falls into the control groove 531 of the rotation control member 53, the second driving gear 421, except for the one with the fewest teeth which is fixed to the countershaft 3, rotates at a speed higher than the second driven gear 422 with the largest number of teeth, and the one-way clutch 93 disengages.

[0069] The one-way clutch 93 can be a roller clutch, wedge clutch, pawl clutch, friction clutch, electromagnetic clutch, etc.

[0070] The rotation control component 53 is located inside the sub-shaft 3, and the drive device 6 is located outside the rotation control component 53. This location on the outside facilitates heat dissipation for the drive device 6 and also makes its assembly easier. The rotation control component 53 can be directly controlled by the drive device 6, but the drive device 6 needs to acquire the rotational speed of the sub-shaft 3 and maintain it at the same speed as the rotation control component 53, which results in significant power consumption.

[0071] To facilitate the control of the rotation control element 53 of the shift mechanism 5, a speed mixing mechanism 7 is provided. Figure 9This is a schematic diagram of the speed mixing mechanism 7. The speed mixing mechanism 7 is connected to the shifting mechanism 5, the countershaft 3, and the drive device 6. When the drive device 6 does not perform a shifting operation, that is, when the drive device 6 does not input rotation to the speed mixing mechanism 7, the speed mixing mechanism 7 causes the rotation control element 53 of the shifting mechanism 5 and the countershaft 3 to rotate synchronously. When the drive device 6 performs a shifting operation, the speed mixing mechanism 7 causes the rotation angle of the rotation control element 53 of the shifting mechanism 5 and the countershaft 3 to deflect.

[0072] The speed mixing mechanism 7 includes a first ring gear 71, a first sun gear 72, a planet carrier 73, a multi-planet gear 74, a second ring gear 76, and a second sun gear 75. The multi-planet gear 74 is rotatably connected to the planet carrier 73 and meshes with the first ring gear 71, the first sun gear 72, the second ring gear 76, and the second sun gear 75 respectively. The first ring gear 71 is connected to the rotation control element 53 of the shifting mechanism 5, the second ring gear 76 is connected to the countershaft 3, the first sun gear 72 is connected to the drive device 6, and the second sun gear 75 is connected to the housing 1.

[0073] The first gear ring 71 and the rotation control component 53 can be either separate or integrated. Separate components are easier to manufacture, while integrated components have higher structural strength. Figure 8 As shown, the first gear ring 71 and the rotation control component 53 are integrally formed.

[0074] The multi-planetary gear 74 can be a double, triple, or more planetary gear set. The more planetary gears there are, the larger the transmission ratio the speed mixing mechanism 7 can achieve. The larger the transmission ratio of the speed mixing mechanism 7, the less torque the drive unit 6 needs to provide under the same load.

[0075] In this embodiment, the multi-planetary gear 74 is a double-planetary gear 741, such as... Figure 9 As shown, the double planetary gear 741 includes a first planetary gear 7411 and a second planetary gear 7412 with the same number of teeth. The first planetary gear 7411 meshes with the first ring gear 71 and the first sun gear 72, respectively, and the second planetary gear 7412 meshes with the second ring gear 76 and the second sun gear 75, respectively. The double planetary gear 741 has a simple structure and is easy to assemble. Since the transmission ratio of the speed mixing mechanism 7 is small, the drive device 6 needs to be a high-torque model.

[0076] When no gear shifting operation is performed, i.e. the drive device 6 does not rotate, the first sun gear 72 is essentially fixed due to the resistance of its output shaft. Since the first planetary gear 7411 and the second planetary gear 7412 of the double planetary gear 741 have the same number of teeth, the rotation control component 53 will be driven by the countershaft 3 and rotate in the same direction and at the same speed.

[0077] When a gear shift is required, the drive unit 6 rotates a certain number of revolutions in either the forward or reverse direction. The speed of the countershaft 3 and the speed of the first sun gear 72 are mixed and output to the rotation control unit 53. Specifically, when the speed of the first sun gear 72 and the speed of the countershaft 3 are in the same direction, the speed of the rotation control unit 53 is the sum of the speeds of the countershaft 3 and the first sun gear 72; when the speeds of the first sun gear 72 and the countershaft 3 are in opposite directions, the speed of the rotation control unit 53 is the difference between the speeds of the countershaft 3 and the first sun gear 72. After the gear shift is completed, the rotation control unit 53 resumes synchronous rotation with the countershaft 3.

[0078] The drive unit 6 is a shift motor, preferably an encoder motor. Encoder motors can acquire real-time information such as the motor's position, speed, and angle through an encoder, offering high measurement accuracy and suitability for applications requiring high precision in position, speed, and angle. The shift motor is fixedly connected to the housing 1, eliminating the need for it to rotate with the countershaft 3, thus avoiding power supply issues and reducing maintenance complexity.

[0079] The torque sensor 12 includes a force-sensitive element 121, a first circuit module 122 connected to the force-sensitive element 121, and a second circuit module 123 wirelessly connected to the first circuit module 122. The second circuit module 123 is used to wirelessly power the first circuit module 122, and the first circuit module 122 is used to wirelessly transmit data to the first circuit module 122. The structure of the first circuit module 122 and the second circuit module 123 is consistent with that of the applicant's patent application CN202422083293.6, and will not be described again here. The first circuit module 122 and the second circuit module 123 are respectively installed in a first housing 124 and a second housing 125 with sealed cavities. Both the first housing 124 and the second housing 125 are annular plastic housings. The second housing 125 is fixed to the outer shell 1 and remains stationary. The first circuit module 122 and the first housing 124 are fixed to the outer circumference of the sub-shaft 3 and rotate with the sub-shaft 3. A gap is left between the first housing 124 and the second housing 125 to allow them to rotate relative to each other. The first housing 124 and the second housing 125 serve to isolate the lubricant of the transmission mechanism 4.

[0080] like Figure 10 and Figure 11As shown, the first circuit module 122 and the second circuit module 123 are positioned at the left end of the sub-shaft 3 for easy assembly and maintenance. The second circuit module 123 is located radially outside the first circuit module 122, utilizing the radial space of the sub-shaft 3 to avoid excessive axial width. A connecting block 126 is fixed on the sub-shaft 3 and is fitted onto the first driven gear 412. Since the first driving gear 411 meshes with the first driven gear 412, the torque of the central shaft 2 is transmitted to the first driven gear 412 through the first driving gear 411 and then to the sub-shaft 3. During the torque transmission process, the connecting block 126 will deform. Therefore, a force-sensitive element 121 is provided on the surface of the connecting block 126. The first circuit module 122 is connected to the force-sensitive element 121 via a cable or contact.

[0081] Force-sensitive element 121 is a sensor element capable of sensing and responding to changes in external force, converting mechanical force (such as pressure, tension, pressure difference, etc.) into electrical signals. Force-sensitive element 121 includes strain gauges, piezoelectric sensors, piezoresistive sensors, force-sensitive resistors, capacitive sensors, etc. In this embodiment, strain gauges are selected as force-sensitive element 121. Strain gauges have high accuracy, small size, and low cost, and can be directly pasted onto the surface of connecting block 126 or embedded into connecting block 126, which can reduce manufacturing costs compared to existing technologies.

[0082] When the torque is transmitted from the central shaft 2 to the secondary shaft 3, the sensitive grid of the strain gauge will undergo slight deformation, thereby changing its resistance. After the torque sensor 12 collects the torque of the secondary shaft 3, it calculates the torque passing through the central shaft 2 based on the transmission ratio of the first driving gear 411 and the first driven gear 412.

[0083] Figure 12 This is a schematic diagram of the crank angles. Let 0 degrees be when the right crank 82 is directly above and the left crank 81 is directly below; 90 degrees be when the right crank 82 is directly to the right and the left crank 81 is directly to the left; 180 degrees be when the right crank 82 is directly below and the left crank 81 is directly above; 270 degrees be when the right crank 82 is directly to the left and the left crank 81 is directly to the right; and 360 degrees be when the right crank 82 is directly above and the left crank 81 is directly below. This is a complete cycle.

[0084] Figure 13This is a graph of the torque collected by torque sensor 12. The process of the rider maintaining a constant pedaling frequency is as follows: When the bottom bracket 2 rotates from 0 degrees forward (D1 direction) to 90 degrees, the pedaling force of the rider's right foot on the pedal and right crank 82 gradually increases, while the left foot does not produce pedaling force on the pedal and left crank 81; when rotating from 90 degrees forward to 180 degrees, the pedaling force of the rider's right foot on the pedal and right crank 82 gradually decreases, while the left foot does not produce pedaling force on the pedal and left crank 81; when rotating from 180 degrees forward to 270 degrees, the pedaling force of the rider's left foot on the pedal and left crank 81 gradually increases, while the right foot does not produce pedaling force on the pedal and right crank 82; when rotating from 270 degrees forward to 360 degrees, the pedaling force of the rider's left foot on the pedal and left crank 81 gradually decreases, while the right foot does not produce pedaling force on the pedal and right crank 82.

[0085] Ultimately, it is reflected in Figure 13 The middle axis represents a sinusoidal wave function, with the expression: T = A |sin(θ)|, and a period of 180 degrees. The vertical axis represents the torque T (Torque) passing through the central axis 2, and the horizontal axis represents the rotation angle θ of the central axis 2. Tmin represents the minimum torque, which occurs at angles of 0 degrees, 180 degrees, 360 degrees, etc.; Tmax represents the maximum torque, which occurs at angles of 90 degrees, 270 degrees, 450 degrees, etc.

[0086] During uphill climbing or high-speed riding, the rider generates a large torque, with Tmax exceeding 80 Nm. If shifting is performed at a high torque, the large meshing force between the pawl 51 and the locking groove 4211 of the second drive gear 421 will hinder the rotation of the rotary control component 53, causing the rotary control component 53 to fail to rotate normally and thus preventing normal shifting. Furthermore, the drive device 6 that drives the rotary control component 53 may become stalled and burn out.

[0087] To avoid the above situation, the torque sensor 12 collects the torque passing through the central shaft 2. When the central shaft 2 rotates in the forward direction and the torque is lower than or equal to the preset value, the drive device 6 drives the shift mechanism 5 to shift gears. This avoids shifting when there is a large biting force between the pawl 51 and the locking groove 4211 of the second drive gear 421, and instead performs shifting when the force is small, so that the rotation control component 53 can rotate normally, thereby improving the success rate and smoothness of shifting.

[0088] When only a bottom bracket derailleur is used, the torque passing through bottom bracket 2 includes the torque generated by the rider's pedaling, and Tmin = 0 Nm. By limiting the torque to between Tmin and Tx for gear shifting, the success rate and smoothness of gear shifting are improved. Preferably, the preset value is 10 Nm, meaning gear shifting is performed within the range of 0-10 Nm. This range accounts for a large proportion of the entire cycle, balancing shift response speed and shift success rate. Alternatively, the preset value can be set to 0 Nm, meaning gear shifting is performed at 0 Nm, only when the rotation angle reaches 0 degrees, 180 degrees, 360 degrees, etc. This results in a slower shift response speed but a higher shift success rate.

[0089] When both a bottom bracket derailleur and an assist motor 10 (mentioned below) are present, the torque passing through the bottom bracket 2 includes the torque generated by the rider's pedaling and the torque generated by the assist motor 10. The torque generated by the assist motor 10 usually changes with the torque generated by the rider's pedaling, and the value of Tmax increases accordingly, while Tmin can be 0 Nm or greater than 0 Nm, depending on the assist mode. Similar to when only a bottom bracket derailleur is present, gear shifts are performed between Tmin and Tx.

[0090] During riding, the rider may pedal backwards. During this backwards pedaling process, the bottom bracket 2 rotates in the opposite direction (D2 direction). At this time, the one-way clutch 93 is disengaged, and the torque sensor 12 collects a torque of 0 Nm. Meanwhile, the meshing force between the pawl 51 and the locking groove 4211 of the second drive gear 421 is small. Therefore, regardless of the angle to which the bottom bracket 2 rotates in the opposite direction, gear shifting can be performed, which can improve the shifting response speed.

[0091] This application also provides a mid-drive motor, including the aforementioned mid-shaft gearbox, enabling the mid-drive motor to have both shifting and electric assist functions. For example... Figure 14 As shown, the difference from the central shaft gearbox is that an auxiliary motor 10 and an auxiliary motor reduction mechanism 11 are added. The auxiliary motor 10 is connected to the transmission mechanism 4. Specifically, the axis of the output shaft of the auxiliary motor 10 is parallel to the axis of the central shaft 2. The auxiliary motor 10 is connected to the first gear set 41 of the transmission mechanism 4 through the auxiliary motor reduction mechanism 11.

[0092] When the assist motor 10 is working, in addition to the torque generated by the rider pedaling, there is also the torque generated by the assist motor 10. The combined torque of the two is output to the output component 92, enabling the rider to achieve higher riding speed or longer riding distance in a less strenuous way.

[0093] A mid-drive motor with shifting function, compared to a rear-drive motor (hub motor) with shifting function, has a shifting structure on the frame instead of the rear wheel. When impacted on rough roads, the impact is not directly transmitted to the hub through the rim and spokes, but is transmitted through the frame. The frame has a certain vibration absorption function, which greatly reduces the impact force. It is relatively less affected by external forces and less prone to bumps, making the mid-drive motor more durable.

[0094] Furthermore, vehicles equipped with a mid-drive motor are also equipped with a speed feedback system. For example, a GPS chip is added to obtain location information and calculate the vehicle's speed. In automatic mode, the rider does not need to operate the vehicle; the mid-drive gearbox performs gear shifting operations based on the vehicle's speed. For instance, when the vehicle speed reaches 10 kilometers per hour, it automatically shifts from first to second gear; conversely, when the vehicle speed drops below 10 kilometers per hour, it automatically shifts from second to first gear. Riders can switch to manual mode to freely change gears according to actual road conditions, increasing riding flexibility, or switch to free mode for automatic gear shifting, improving riding comfort.

[0095] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with the described embodiment or example is included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0096] The above descriptions are merely some embodiments of this utility model. For those skilled in the art, various modifications and improvements can be made without departing from the inventive concept of this utility model, and all such modifications and improvements fall within the protection scope of this utility model.

[0097] The above are all preferred embodiments of the present invention / utility model, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A mid-shaft transmission, characterized in that, include: The central axle (2) is rotatably supported on the frame, and torque is input from the central axle (2); The secondary shaft (3) is hollow and parallel to the central shaft (2); The transmission mechanism (4) is connected to the central shaft (2) and the secondary shaft (3) respectively, and has at least two transmission ratios; The drive unit (6) is connected to the shifting mechanism (5) and is located on the outside of the subshaft (3); The shifting mechanism (5) is linked with the transmission mechanism (4) and is used to change the transmission ratio of the transmission mechanism (4); The output component (92) is fixed to the transmission mechanism (4) and outputs torque; A torque sensor (12) detects the torque passing through the central shaft (2). When the central shaft (2) rotates in the positive direction and is below or equal to a preset value, the drive device (6) drives the shifting mechanism (5) to perform a shift.

2. The central shaft transmission according to claim 1, characterized in that, The preset value is 10 Nm.

3. The central shaft transmission according to claim 1, characterized in that, The gear shift is performed when the preset value is 0 Nm.

4. The central shaft transmission according to claim 2, characterized in that, The central shaft (2) rotates in the opposite direction to immediately perform a gear shift.

5. The central shaft transmission according to claim 1, characterized in that, The torque sensor (12) includes a force-sensitive element (121), a first circuit module (122) connected to the force-sensitive element (121), and a second circuit module (123) wirelessly connected to the first circuit module (122). The force-sensitive element (121) is disposed on the sub-shaft (3), and the first circuit module (122) rotates synchronously with the sub-shaft (3).

6. The central shaft transmission according to claim 1, characterized in that, The shifting mechanism (5) includes at least two pawls (51), a reset member (52), and a rotation control member (53). The sub-shaft (3) has a groove (31). The pawl (51) is rotatably installed in the groove (31). One end of the reset member (52) abuts against the sub-shaft (3), and the other end of the reset member (52) abuts against the pawl (51). The outer circumferential surface of the rotation control member (53) is provided with a control groove (531), and the pawl (51) is located on the outside of the rotation control member (53). When the rotation angle between the rotation control component (53) and the countershaft (3) deflects, one end of the pawl (51) falls into the control groove (531), fixing the gear of the shifting mechanism (5) to the countershaft (3) to change the transmission ratio.

7. The central shaft transmission according to claim 6, characterized in that, The rotation control element (53) is located inside the sub-shaft (3), and the drive device (6) is located outside the rotation control element (53).

8. The central shaft transmission according to claim 6, characterized in that, The control slot (531) consists of at least two spirally arranged through slots, which are opened along the circumference of the rotation control member (53), and adjacent through slots are not connected.

9. The central shaft transmission according to claim 6, characterized in that, The torque passing through the central axis (2) includes the torque generated by the rider's pedaling.

10. A mid-drive motor, comprising a mid-shaft gearbox as described in any one of claims 1-9, characterized in that, It also includes a power assist motor (10) and a power assist motor reduction mechanism (11), wherein the power assist motor (10) is connected to the transmission mechanism (4) through the power assist motor reduction mechanism (11).

11. The mid-drive motor according to claim 10, characterized in that, The torque passing through the central shaft (2) includes the torque generated by the rider's pedaling and the torque generated by the power assist motor (10).

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