Gear support structure, intermediate shaft transmission and mid-motor

Abstract

The utility model belongs to the technical field of transmission, especially relates to a gear bearing structure, central shaft transmission and centrally -placed motor, the utility model discloses a gear bearing structure is used for central shaft transmission, and central shaft transmission includes the transmission mechanism of setting in the shell, and the transmission mechanism includes sun gear, planet carrier, planetary gear and ring gear, and planet carrier is connected with the central shaft, and planetary gear rotatably bears in planet carrier, and planetary gear is engaged with sun gear outside, and ring gear is engaged with planetary gear inside, and the shell is provided with the supporting portion, and sun gear is supported on the supporting portion, the gear bearing structure of the application, and the shell of central shaft transmission is provided with the supporting portion, and sun gear is supported on the supporting portion. The central shaft can not produce interference even if producing slight deformation, so can not produce abnormal sound.

Description

Technical Field

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

[0002] Chinese patent document CN215883967U discloses a three-speed gearbox for a mid-drive motor and its mid-drive motor. The output sun gear is supported on the bushing by a sun gear support bearing, and the bushing is supported on the bottom bracket by a bushing support bearing. However, the strong pedaling force applied to the bottom bracket by the rider during pedaling will cause it to deform slightly, and the bottom bracket and bushing will interfere with each other, causing abnormal noise and affecting the riding experience. Utility Model Content

[0003] The purpose of this application is to provide a gear support structure, a bottom-shaft derailleur, and a mid-mounted motor that will not produce abnormal noise and improve the riding experience.

[0004] To solve the above-mentioned technical problems, this application provides a gear support structure for a central shaft transmission. The central shaft transmission includes a transmission mechanism disposed within a housing. The transmission mechanism includes a sun gear, a planet carrier, planet gears, and a ring gear. The planet carrier is connected to the central shaft. The planet gears are rotatably supported on the planet carrier. The planet gears externally mesh with the sun gear, and the ring gear internally meshes with the planet gears. The housing is provided with a support portion, and the sun gear is supported on the support portion.

[0005] Furthermore, the support portion is cylindrical, and the inner diameter of the support portion is larger than the outer diameter of the central shaft.

[0006] Furthermore, a bearing is provided between the support portion and the sun gear.

[0007] Furthermore, the bearing is a rolling bearing.

[0008] Furthermore, the rolling bearing is a needle roller bearing.

[0009] Furthermore, adjacent bearings are arranged in an axially staggered manner.

[0010] Furthermore, the outer casing includes an outer casing body, a first end cap, and a second end cap, the first end cap and the second end cap being fastened to both sides of the outer casing body, and the support portion being disposed on the first end cap.

[0011] Furthermore, the sun gear is integrally formed with the bushing, and the bearing is installed between two adjacent bushings. This application also provides a mid-shaft transmission, including the above-described gear support structure, and further comprising:

[0012] A center axle, which is rotatably supported on the frame, and from which torque is input;

[0013] A transmission mechanism having at least two transmission ratios;

[0014] A shifting mechanism, linked to the transmission mechanism, is used to change the transmission ratio of the transmission mechanism;

[0015] A drive unit is connected to the gear shifting mechanism;

[0016] The output component is connected to the transmission mechanism to output torque.

[0017] This application also provides a mid-drive motor, including the aforementioned mid-shaft gearbox, and further including an assist motor, the assist motor being connected to the mid-shaft or the transmission mechanism.

[0018] As can be seen from the above, in the gear support structure of this application, the housing of the central shaft gearbox is provided with a support portion, and the sun gear is supported on the support portion. Even if the central shaft undergoes slight deformation, there will be no interference, and therefore no abnormal noise will be generated.

[0019] 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

[0020] Figure 1 This is a 3D view of the central shaft transmission.

[0021] Figure 2 This is a cross-sectional view of the central shaft transmission.

[0022] Figure 3 A perspective view of the central shaft gearbox (with the housing, output components, and crankshaft hidden).

[0023] Figure 4 This is a three-dimensional view of the central shaft gearbox (with the housing, output components, and crankshaft hidden).

[0024] Figure 5 This is a simplified structural diagram of the central shaft transmission.

[0025] Figure 6 This is an exploded view of the gear shifting mechanism.

[0026] Figure 7 This is a cross-sectional view of the gear shifting process of the gear shifting mechanism.

[0027] Figure 8 A 3D view of the locking components, bushings, and sun gear before assembly.

[0028] Figure 9 A 3D view of the locking components, bushings, and sun gear after assembly.

[0029] Figure 10 This is a three-dimensional view of the gear support structure.

[0030] Figure 11 This is a cross-sectional view of the gear support structure.

[0031] Figure 12 This is a 3D view of the gear shifting mechanism in the first gear position.

[0032] Figure 13 This is a 3D view of the shift mechanism in the second gear position.

[0033] Figure 14 This is a 3D view of the gear shift mechanism in the third gear position.

[0034] Figure 15 This is a 3D view of the gear shift mechanism in the fourth gear position.

[0035] Figure 16 This is a power transmission path diagram for the first gear of the central shaft transmission.

[0036] Figure 17 This is a diagram showing the power transmission path for the second gear of the central shaft transmission.

[0037] Figure 18 This is a power transmission path diagram for the third gear of the central shaft transmission.

[0038] Figure 19 This is a power transmission path diagram for the fourth gear of the central shaft transmission.

[0039] Figure 20 This is a 3D view of a mid-drive motor (with the housing, output components, and crank hidden).

[0040] Figure 21 This is a 3D view of the mid-drive motor (without housing, output components, or crank).

[0041] Figure 22 This is a simplified structural diagram of a mid-drive motor.

[0042] Explanation of reference numerals in the attached figures:

[0043] 1-Outer shell, 11-Outer shell body, 12-First end cap, 13-Second end cap, 14-Support part,

[0044] 2-Central axis,

[0045] 3-Input component, 31-Left crank, 32-Right crank

[0046] 4-Output components,

[0047] 5-Transmission mechanism, 51-Planet carrier, 52-Sun gear, 521-First sun gear, 522-Second sun gear, 523-Third sun gear, 53-Planet gear, 531-First planet gear, 532-Second planet gear, 533-Third planet gear, 54-Ring gear, 55-First clutch assembly, 56-Second clutch assembly

[0048] 6-Shifting mechanism, 61-Pawl, 611-First pawl, 612-Second pawl, 613-Third pawl, 61A-Locking part, 61B-Control part, 61C-Rotating shaft part, 62-Rotation control component, 621-Control groove, 622-Gear tooth, 63-Locking component, 631-First locking component, 632-Second locking component, 633-Third locking component, 63A-Locking groove, 64-Busset, 641-First bushing, 642-Second bushing, 643-Third bushing, 65-Bracket, 66-Bearing, 661-First bearing, 662-Second bearing, 663-

[0049] Third bearing,

[0050] 7-Drive unit,

[0051] 8-First reduction gear, 9-Assist motor

[0052] 10-Second deceleration mechanism. Detailed Implementation

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] The following disclosure provides many different embodiments or examples for implementing various structures of this invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0058] Figure 1 This is a 3D view of the central shaft transmission. Figure 2 This is a cross-sectional view of the central shaft transmission. Figure 3 This is a perspective view of the central shaft transmission (with housing 1, output component 4, and crankshaft hidden). Figure 4 This is a perspective view of the bottom bracket derailleur (with housing 1, output component 4, and cranks hidden) from another angle. The bottom bracket derailleur of this application is fixedly mounted at the bottom center of the vehicle frame. The derailleur includes housing 1, bottom bracket 2, transmission mechanism 5, shifting mechanism 6, drive unit 7, and output component 4. Housing 1 is fixed to the frame. Except for the output component 4, all other parts are concealed inside housing 1. Both ends of bottom bracket 2 extend from housing 1 and are rotatably supported on the frame. Input components 3 are fixedly connected to both ends of bottom bracket 2. Input components 3 include a left crank 31 and a right crank 32. The cranks are rotatably connected to pedals. The rider transmits the torque generated by pedaling to bottom bracket 2, which is then input to transmission mechanism 5. Transmission mechanism 5 is used to adjust the gear ratio and output speed. Different gears are switched by changing the meshing relationship of different planetary gears. Output component 4 is fixed to transmission mechanism 5 and is used to output torque. Output component 4 then inputs torque to the flywheel via chain drive, belt drive, or shaft drive, driving the rear wheel of the vehicle to rotate.

[0059] 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.

[0060] The outer casing 1 includes a main body 11, a first end cap 12, and a second end cap 13. The main body 11 has a columnar structure with openings on both sides. The first end cap 12 and the second end cap 13 are respectively fastened to both sides of the main body 11, that is, the first end cap 12 and the second end cap 13 are installed at the openings on both sides by screws to achieve internal sealing. Providing two end caps facilitates the assembly of internal parts. The main body 11 can also be integrally formed with the first end cap 12 or the second end cap 13 to increase structural strength.

[0061] Planetary gear drives are compact and can transmit high torque in limited spaces, making them particularly suitable for applications requiring high torque and a compact design. Bicycles have high requirements for space utilization of components; larger components can affect rider maneuverability. Therefore, using a planetary gear mechanism can reduce the overall size of the bottom bracket derailleur.

[0062] In this embodiment, the transmission mechanism 5 is a planetary gear mechanism, including a planet carrier 51, planetary gears 53, a sun gear 52, and a ring gear 54. The planetary gears 53 are rotatably supported on the planet carrier 51. The planetary gears 53 externally mesh with the sun gear 52, and the ring gear 54 internally meshes with the planetary gears 53. Multiple planetary gears 53 and sun gears 52 are provided; the more planetary gears 53 and sun gears 52 there are, the more gears the transmission mechanism 5 has. To achieve four gears in the central shaft transmission, such as... Figure 5 As shown, the transmission mechanism 5 specifically includes a planetary carrier 51, a first sun gear 521, a second sun gear 522, a third sun gear 523, a gear ring 54, a first planetary gear 531, a second planetary gear 532, and a third planetary gear 533. The connection and meshing relationships of the various parts of the planetary gear mechanism are as follows:

[0063] The first planetary gear 531, the second planetary gear 532, and the third planetary gear 533 are fixedly connected and rotatably supported on the planet carrier 51. The first sun gear 521, the second sun gear 522, and the third sun gear 523 are all rotatably supported on the central shaft 2. The planet carrier 51 is fixedly connected to the central shaft 2. The first planetary gear 531 meshes externally with the first sun gear 521, the second planetary gear 532 meshes externally with the second sun gear 522, and the third planetary gear 533 meshes externally with the third sun gear 523. The gear ring 54 meshes internally with the third planetary gear 533 and is fixedly connected to the output component 4.

[0064] A first clutch assembly 55 is provided between the planetary carrier 51 and the ring gear 54. The first clutch assembly 55 is configured to engage when the rotational speed of the ring gear 54 is lower than or equal to the rotational speed of the planetary carrier 51, causing the ring gear 54 to rotate synchronously with the planetary carrier 51; and disengage when the rotational speed of the ring gear 54 is higher than the rotational speed of the planetary carrier 51, causing the planetary carrier 51 to stop rotating with the ring gear 54. The first clutch assembly 55 can be a roller clutch, a wedge clutch, a pawl clutch, a friction clutch, an electromagnetic clutch, etc.

[0065] To achieve gear shifting, the shifting mechanism 6 locks or releases the sun gear 52 of the planetary gear mechanism. For example... Figures 6-7As shown, the shifting mechanism 6 includes at least two pawls 61, at least two rotary control members 62, an elastic member (not shown), a bracket 65, and a locking member 63. The rotary control member 62 has a cylindrical structure with a control groove 621 on its outer circumference and a locking member 63 installed on its inner side. The locking member 63 has a disc-shaped structure with a locking groove 63A on its outer circumference. Pawls 61 are installed between the locking member 63 and the rotary control member 62. The pawls 61 are rotatably mounted on the bracket 65, and the bracket 65 is fixed to the outer casing 1.

[0066] Specifically, each pawl 61 has a locking part 61A, a control part 61B, and a rotating shaft part 61C. The rotating shaft part 61C is a circular through hole, which is fitted onto a rotating shaft to allow the pawl 61 to rotate around the shaft. Both the control part 61B and the locking part 61A of the pawl 61 protrude along the thickness direction of the pawl 61. The control part 61B is located on the side opposite to the locking part 61A, and the locking part 61A is used to lock or release with the locking groove 63A of the locking member 63.

[0067] By providing an elastic element on the rotating shaft, the control part 61B of the pawl 61 can be kept in contact with the inner wall of the rotation control member 62. The elastic element can be a torsion spring, with one end of the torsion spring abutting one end of the pawl 61 and the other end of the torsion spring abutting the bracket 65. The torsion spring applies a torque toward the rotation control member 62 to the pawl 61.

[0068] In order to achieve the rotation of the rotary control component 62, an electric shift mechanism is used for driving in this embodiment. The electric shift mechanism includes a drive device 7, which is an encoder motor. The encoder motor can obtain information such as the position, speed and angle of the motor movement in real time through the encoder, and has high measurement accuracy and precision, which is suitable for application scenarios with high requirements for position, speed and angle precision.

[0069] The output end of the drive device 7 is connected to a first reduction mechanism 8, which can be a multi-stage gear reducer. The first reduction mechanism 8 reduces the rotational speed of the drive device 7 and increases the torque, making it easier to overcome the resistance of the pawl 61 to the rotational control member 62 and drive the rotational control member 62 to rotate. The outer circumferential surface of the rotational control member 62 is also provided with gear teeth 622. The first reduction mechanism 8 meshes with the gear teeth 622 of the rotational control member 62 to realize transmission.

[0070] It should be noted that, in addition to the electric shift mechanism, a manual shift mechanism can also be used to drive the rotary control component 62 for shifting.

[0071] Since there are three sun gears 52, there are also three pawls 61, including a first pawl 611, a second pawl 612, and a third pawl 613. The first pawl 611 is closer to the output component 4, and the third pawl 613 is farther away from the output component 4. The first pawl 611, the second pawl 612, and the third pawl 613 are staggered in the circumferential direction. When the rotation control component 62 rotates to a certain angle, only one end of the pawl 61 falls into the control groove 621 and bounces up, while the other pawls 61 remain retracted.

[0072] The number of locking elements 63 corresponds to the number of sun gears 52. There are three locking elements 63, namely the first locking element 631, the second locking element 632 and the third locking element 633. The outer diameters of the first locking element 631, the second locking element 632 and the third locking element 633 are the same, and the inner diameters decrease sequentially.

[0073] Locking element 63 is fixedly connected to the sun gear 52 of transmission mechanism 5. For ease of assembly, such as... Figure 8 and Figure 9 As shown, a bushing 64 is provided between the locking member 63 and the sun gear 52. The bushing 64 is a hollow shaft-like part, and its number corresponds to that of the locking member 63. Specifically, the bushing 64 includes a first bushing 641, a second bushing 642, and a third bushing 643. The lengths of the first bushing 641, the second bushing 642, and the third bushing 643 increase sequentially, while their outer diameters decrease sequentially. The three bushings 64 can rotate relative to each other. A bearing 66 can be provided between two adjacent bushings 64 to reduce rolling resistance and ensure load-bearing capacity.

[0074] Bearing 66 includes rolling bearings and sliding bearings. Rolling bearings reduce friction by using rolling elements (such as balls, cylindrical rollers, tapered rollers, needle rollers, etc.) rolling between inner and outer rings. They are characterized by a large radial dimension, a low coefficient of friction, and high transmission efficiency. Sliding bearings support the rotating shaft through sliding contact between smooth surfaces (such as bearing shells and journals). They are characterized by a small radial dimension and high friction and wear. Since riders require high transmission efficiency, rolling bearings with high transmission efficiency are selected in this embodiment.

[0075] Rolling bearings are classified into ball bearings and roller bearings according to the type of rolling elements. Bearings with spherical rolling elements are called ball bearings; bearings with rolling elements, including cylindrical rollers, tapered rollers, barrel rollers, helical rollers, and needle rollers, are called roller bearings.

[0076] Needle roller bearings have a large number of needles and a large contact area, allowing them to withstand greater radial loads than ball bearings of the same dimensions. They also offer high load-carrying capacity. Furthermore, needle roller bearings save space due to their small radial dimensions and low cross-sectional height, enabling them to provide high load-carrying capacity within a limited space. Therefore, needle roller bearings are the preferred choice for rolling bearings.

[0077] The bushing 64 can be integrally formed with the sun gear 52 or the locking member 63. In this embodiment, the bushing 64 is integrally formed with the sun gear 52, which ensures the strength of the sun gear 52. The bushing 64 and the locking member 63 are fixed by a spline connection, that is, a spline groove is provided on the inner side of the locking member 63, and a spline is provided on the end of the bushing 64, and the two are assembled together. The bushing 64 and the locking member 63 can also be fixed by other methods, such as square hole connection, threaded connection, etc.

[0078] When cyclists ride at high cadence or climb steep hills, the bottom bracket 2 needs to withstand high torque, resulting in slight bending and torsional deformation. If the bottom bracket 2 directly supports the sun gear 52, interference will occur between the bottom bracket 2 and the sun gear 52, producing abnormal noise. To solve this problem, such as... Figure 11 and Figure 12 As shown, the outer casing 1 is provided with a support portion 14, on which the sun gear 52 is supported. Specifically, the support portion 14 is cylindrical, which is easy to process. The inner diameter of the support portion 14 is larger than the outer diameter of the central shaft 2, and there is a certain gap between the support portion 14 and the central shaft 2. Through this gear support structure, even if the central shaft 2 undergoes a slight deformation, it will not interfere, and therefore will not produce abnormal noise.

[0079] The support part 14 can be set on the first end cover 12. The support part 14 is first fixed to the first end cover 12 with screws, and then the first end cover 12 is fixed to the outer shell body 11 with screws. This can reduce the assembly difficulty and simplify the assembly process.

[0080] In addition to the bearing 66 being provided between two adjacent bushings 64, a bearing 66 is also provided between the support portion 14 and the third sun gear 523.

[0081] The assembly process of the three bushings 64 and the three locking parts 63 is as follows:

[0082] Step 1: Fit the second bushing 642 onto the third bushing 643 and install the second bearing 662; fit the first bushing 641 onto the second bushing 642 and install the third bearing 663. Step 2: Assemble the first locking member 631 onto the first bushing 641; assemble the second locking member 632 onto the second bushing 642; assemble the third locking member 633 onto the third bushing 643. Step 3: Fit the support part 14 onto the third bushing 643 and install the first bearing 661. After assembly, the positional relationship of the parts from the inside out is as follows: central shaft 2, support part 14, first bearing 661, third bushing 643 and third sun gear 523, second bearing 662, second bushing 642 and second sun gear 522, third bearing 663, first bushing 641 and first sun gear 521. This assembly method ensures the compactness of the structure.

[0083] Adjacent bearings 66 are arranged in an axially staggered manner, meaning that the first bearing 661 and the second bushing 642 do not overlap in the radial region, and the second bushing 642 and the third bushing 643 also do not overlap in the radial region. This arrangement of bearings 66 can avoid stress concentration and reduce the deformation of the support portion 14. It should be noted that the first bearing 661 and the third bushing 643 may or may not overlap in the radial region.

[0084] The shift mechanism 6 is in the following states during the shifting process: In the initial position, the shift mechanism 6 is in the first gear, such as... Figure 12 As shown, the first pawl 611, the second pawl 612, and the third pawl 613 have not fallen into the control slot 621; the drive device 7 drives the first reduction mechanism 8 to drive the rotation control component 62 of the shift mechanism 6 to rotate counterclockwise, and the shift mechanism 6 is in the second gear position, as shown. Figure 13 As shown, the first pawl 611 and the second pawl 612 did not fall into the control groove 621, only the third pawl 613 fell into the control groove 621; the rotation control component 62 continued to rotate counterclockwise by a certain angle, and the shifting mechanism 6 was in the third gear position, as shown. Figure 14 As shown, the first pawl 611 and the third pawl 613 did not fall into the control groove 621, only the second pawl 612 fell into the control groove 621; the rotation control component 62 continued to rotate counterclockwise by a certain angle, and the shifting mechanism 6 was in the fourth gear position, as shown. Figure 15 As shown, the second pawl 612 and the third pawl 613 did not fall into the control groove 621, only the first pawl 611 fell into the control groove 621. The above process is the upshifting process, and the rotation control component 62 rotates in the opposite direction during the downshifting process.

[0085] Figures 16-19 The rectangular frame of the first clutch assembly 55 is blacked out to indicate that it is in the engaged state, and uncolored to indicate that it is in the disengaged state; the rectangular frame of the pawl 61 is blacked out to indicate that it is in the locked state, and uncolored to indicate that it is in the released state.

[0086] Figure 16 The power transmission path diagram for the first gear of the central shaft transmission is shown.

[0087] As shown in the figure, the shifting mechanism 6 does not lock the sun gear 52, and the first sun gear 521, the second sun gear 522, and the third sun gear 523 can all rotate. The planet carrier 51 and the ring gear 54 rotate at the same speed. The first clutch assembly 55 is engaged, and the torque passes through the central shaft 2, the planet carrier 51, the first clutch assembly 55, the ring gear 54, and the output component 4 in sequence. At this time, the transmission ratio of the transmission mechanism 5 is 1.

[0088] Figure 17 The power transmission path diagram for the second gear of the central shaft transmission is shown.

[0089] As shown in the figure, the shifting mechanism 6 locks the third sun gear 523, while the first sun gear 521 and the second sun gear 522 can rotate. The planetary carrier 51 is the driving gear, the first sun gear 521 is fixed, and the ring gear 54 is the driven gear. This is a speed-increasing transmission with a transmission ratio less than 1. The rotational speed of the ring gear 54 is higher than that of the planetary carrier 51, and the first clutch assembly 55 disengages. The torque passes sequentially through the central shaft 2, planetary carrier 51, third planetary gear 533, third sun gear 523, ring gear 54, and output component 4.

[0090] Figure 18 The diagram shows the power transmission path for the third gear of the central shaft transmission.

[0091] As shown in the figure, the shifting mechanism 6 locks the second sun gear 522, while the first sun gear 521 and the third sun gear 523 can rotate. The planetary carrier 51 is the driving gear, the second sun gear 522 is fixed, and the ring gear 54 is the driven gear. This is a speed-increasing transmission. The transmission ratio of the third gear is less than that of the second gear, and the rotational speed of the ring gear 54 is higher than that of the planetary carrier 51. The first clutch assembly 55 disengages. The torque passes sequentially through the central shaft 2, planetary carrier 51, second planetary gear 532, second sun gear 522, third planetary gear 533, ring gear 54, and output component 4.

[0092] Figure 19 The diagram shows the power transmission path for the fourth gear of the central shaft transmission.

[0093] As shown in the figure, the shifting mechanism 6 locks the first sun gear 521, while the second sun gear 522 and the third sun gear 523 can rotate. The planetary carrier 51 is the driving gear, the first sun gear 521 is fixed, and the ring gear 54 is the driven gear. This is a speed-increasing transmission. The transmission ratio of the fourth gear is less than that of the third gear, and the rotational speed of the ring gear 54 is higher than that of the planetary carrier 51. The first clutch assembly 55 disengages. The torque passes sequentially through the central shaft 2, planetary carrier 51, first planetary gear 531, first sun gear 521, third planetary gear 533, ring gear 54, and output component 4.

[0094] 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... Figures 20-22 As shown, the difference from the central shaft gearbox lies in the addition of an assist motor 9 and a second reduction mechanism 10. The assist motor 9 can be connected to the central shaft 2 or to the transmission mechanism 5. The connection method can be any of chain drive, belt drive, or gear drive. In this embodiment, the assist motor 9 and the transmission mechanism 5 are connected via gear drive. Specifically, the axis of the output shaft of the assist motor 9 is parallel to the axis of the central shaft 2. The parallel arrangement structure is simple and easy to assemble and maintain. The assist motor 9 can be directly connected to the transmission mechanism 5, or it can be connected to the gear ring 54 of the transmission mechanism 5 through the second reduction mechanism 10. The second reduction mechanism 10 can be a planetary gear reduction mechanism.

[0095] A second clutch assembly 56 is provided between the assist motor 9 and the gear ring 54. The assist motor 9 is connected to a second reduction mechanism 10. The second clutch assembly 56 can be located between the second reduction mechanism 10 and the gear ring 54. The second clutch assembly 56 is configured to engage when the speed of the gear ring 54 is lower than or equal to the speed of the second reduction mechanism 10, causing the gear ring 54 to rotate synchronously with the second reduction mechanism 10. When the speed of the gear ring 54 is higher than the speed of the second reduction mechanism 10, the clutch assembly 56 disengages, and the second reduction mechanism 10 does not rotate with the gear ring 54. The function of the second clutch assembly 56 is that when the battery supplying power to the assist motor 9 is depleted, the assist motor 9 does not work, the speed of the second reduction mechanism 10 is zero, the second clutch assembly 56 disengages, and the rider's pedaling will only drive the transmission mechanism 5 to rotate, not the assist motor 9 and the second reduction mechanism 10, thus reducing riding resistance.

[0096] When the assist motor 9 is working, in addition to the torque generated by the rider's pedaling, there is also the torque generated by the assist motor 9. The combined torque of the two is output to the output component 4, enabling the rider to achieve higher riding speed or longer riding distance in a less strenuous way.

[0097] 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.

[0098] The weight of a rear-mounted motor is concentrated on the rear wheel, which is not conducive to the vehicle's take-off and jumping. In contrast, the weight of a mid-mounted motor is concentrated on the lower part of the frame's center of gravity, which has less impact on the overall balance of the vehicle and can greatly improve handling performance.

[0099] Vehicles equipped with a mid-mounted gearbox also feature 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 requires no operation; the mid-mounted gearbox shifts gears based on the vehicle's speed. For instance, when the speed reaches 10 km / h, it automatically shifts from first to second gear; conversely, when the speed drops below 10 km / h, it automatically shifts from second to first gear. Riders can switch to manual mode to freely change gears based on actual road conditions, increasing riding flexibility, or switch to free mode for automatic gear changes, enhancing riding comfort.

[0100] 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.

[0101] 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.

Claims

1. A gear support structure for a central shaft transmission, characterized in that, The central shaft transmission includes a transmission mechanism (5) disposed within a housing (1). The transmission mechanism (5) includes a sun gear (52), a planet carrier (51), planet gears (53), and a ring gear (54). The planet carrier (51) is connected to the central shaft (2). The planet gears (53) are rotatably supported on the planet carrier (51). The planet gears (53) mesh externally with the sun gear (52), and the ring gear (54) meshes internally with the planet gears (53). The housing (1) is provided with a support portion (14), and the sun gears (52) are supported on the support portion (14).

2. The gear support structure according to claim 1, characterized in that, The support part (14) is cylindrical, and the inner diameter of the support part (14) is larger than the outer diameter of the central shaft (2).

3. The gear support structure according to claim 2, characterized in that, A bearing (66) is provided between the support (14) and the sun gear (52).

4. The gear support structure according to claim 3, characterized in that, The bearing (66) is a rolling bearing.

5. The gear support structure according to claim 4, characterized in that, The rolling bearing is a needle roller bearing.

6. The gear support structure according to claim 3, characterized in that, The two adjacent bearings (66) are arranged alternately in the axial direction.

7. The gear support structure according to claim 1, characterized in that, The outer shell includes an outer shell body (11), a first end cap (12) and a second end cap (13), the first end cap (12) and the second end cap (13) are respectively fastened to both sides of the outer shell body (11), and the support part (14) is disposed on the first end cap (12).

8. The gear support structure according to claim 3, characterized in that, The sun gear (52) is integrally formed with the bushing (64), and the bearing (66) is installed between two adjacent bushings (64).

9. A central shaft transmission, characterized in that, Including the gear support structure as described in any one of claims 1-8, further comprising: A central axle (2) is rotatably supported on the frame, and torque is input from the central axle (2); A transmission mechanism (5) having at least two transmission ratios; The shifting mechanism (6) is linked with the transmission mechanism (5) and is used to change the transmission ratio of the transmission mechanism (5); The drive unit (7) is connected to the shifting mechanism (6); The output component (4) is connected to the transmission mechanism (5) to output torque.

10. A mid-drive motor, characterized in that, The system includes the central shaft transmission as described in claim 9, and also includes a power assist motor (9) connected to the central shaft (2) or the transmission mechanism (5).

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