Bicycle center-mounted transmission

Abstract

To provide a center-mounted transmission for a bicycle. [Solution] A center-mounted transmission device comprising an outer case, an output shaft, a motor, and a clutch unit. The clutch unit is disposed within the outer case and comprises a drive gear, a clutch gear, an output gear, and an actuating mechanism. The drive gear is connected to the motor, the clutch gear is axially movably installed within the drive gear and comprises a magnetically attractable material, the output gear is connected to the output shaft and is detachably connected to the clutch gear. The actuating mechanism has magnetic attraction and comprises a housing, an actuator axially movable within the housing, and an elastic member that biases the actuating mechanism and the housing. When the actuator is rotated and moved, the clutch gear engages with the output gear, and then the elastic member and the actuating mechanism return the actuator to its original position. After the clutch gear and the output gear are separated, the actuating mechanism returns the clutch gear to its original position.

Description

[Technical Field]

[0001] The present invention relates to transmissions, and more particularly to center-mounted transmissions for bicycles. [Background technology]

[0002] An electrically assisted bicycle is a vehicle that uses an on-board electric motor to assist the rider in pedaling. The electric motor can be mounted on the front or rear wheel of the bicycle, or in different positions on the frame. Among these are center-mounted motors (also called mid-drive units or mid-shipped electric motors) that are mounted around the crankshaft (bottom bracket) of the bicycle, which allows the auxiliary power from the motor to be transmitted directly to the crankshaft of the bicycle, improving transmission efficiency and enabling more effective pedaling assistance.

[0003] According to the Road Traffic Act, the maximum speed of an electrically assisted bicycle is limited, and when the speed reaches the legal limit, the power supply to the motor must be automatically cut off, thereby ceasing the pedaling assist. However, since the motor's transmission is still connected at this time, the driven member within the transmission reversely drives the driving member. This can cause the pedaling to suddenly become heavy, particularly in the case of a center-mounted motor, and can be a significant drain on the rider's physical strength. Therefore, it is necessary to equip the bicycle with a clutch mechanism that separates the driving member and driven member of the transmission when the power supply to the motor is cut off. Such a clutch mechanism can prevent the above problem and also reduce wear on the components within the transmission.

[0004] Furthermore, because the transmission device of a center-mounted motor is attached to the bicycle crankshaft, it is constantly subjected to vibrations caused by the rider's pedaling. Furthermore, while the center-mounted motor transmission device has a compact structure, it incorporates a complex multi-stage reduction mechanism. The current challenge facing the industry has been how to design a clutch mechanism that can withstand continuous vibrations and function stably in such a limited space. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. US11993343B1 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention was made in consideration of the shortcomings of the prior art, and aims to provide a center-mounted transmission device for bicycles that has a simple structure, is resistant to vibration, operates stably, and is equipped with a clutch mechanism that can properly separate and join the driving and driven members of the transmission device. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention proposes a bicycle center-mounted transmission device, which includes an outer shell case having two opposing side surfaces, an output shaft that passes through the two opposing side surfaces of the outer shell case, a motor installed within the outer shell case, and a clutch unit installed within the outer shell case that connects the output shaft and the motor, the output shaft has transmission teeth formed so as to protrude from its outer circumferential surface, The clutch unit includes a drive gear, a clutch gear, an output gear, and an operating mechanism, of which the drive gear is connected to the motor and driven by the motor, an outer peripheral gear connected to the motor is formed on the outer peripheral surface of the drive gear, and an inner peripheral gear is formed on the inner peripheral surface of the drive gear, The clutch gear is installed within the drive gear so as to be movable along the axial direction of the drive gear, and includes a magnetically attractable material; an outer peripheral surface of the clutch gear is formed with a toothed portion that meshes with an inner peripheral gear of the drive gear; one end surface of the clutch gear is formed with a plurality of first meshing claws that are formed so as to surround the center of rotation of the clutch gear and are connected to each other; and the other end surface of the clutch gear is formed with a first abutment portion; the output gear is rotatably connected to the output shaft and detachably connected to the clutch gear, an output gear portion that meshes with the transmission teeth portion of the output shaft is formed on the outer circumferential surface of the output gear, a plurality of second meshing claws are formed on the end surface of the output gear that faces the clutch gear, the plurality of second meshing claws are formed so as to surround the rotation center of the output gear and are connected to each other, and the plurality of second meshing claws and the plurality of first meshing claws can be selectively meshed with each other, The actuation mechanism is disposed on the side of the clutch gear opposite to the side facing the output gear, has a magnetic attraction force, and includes a housing, an actuator, and an elastic member, the housing including a surrounding storage space, an opening facing the clutch gear and communicating with the storage space, an inner bottom wall surface located in the storage space and facing the opening, and a first sliding portion formed on the inner bottom wall surface, the actuator is installed in the storage space movably along the axial direction of the housing, and includes a second abutment portion and a second sliding portion. the second abutment portion is formed on a side surface of the actuator facing the opening and detachably abuts against the first abutment portion, and the second abutment portion and the first abutment portion are connected so as to abut against each other, thereby causing the clutch gear to rotate and drive the actuator; the second sliding portion is formed on a side surface of the actuator facing the inner bottom wall surface and is slidable relative to the first sliding portion; and the elastic member is disposed within the accommodating space and biases the actuator and the housing so as to abut against the periphery of the opening. [Effects of the Invention]

[0008] In the center-mounted bicycle transmission device of the present invention, which has the above technical means, when the power supply to the motor is cut off and the provision of pedaling assist power stops, the clutch gear and the output gear can be properly separated, thereby preventing the phenomenon of sudden heavy pedaling and reducing wear on the clutch gear and the output gear. Meanwhile, when the power supply to the motor is resumed and the provision of pedaling assist power resumes, the actuator is activated and the clutch gear and the output gear are engaged, thereby rotating the output shaft. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is an external perspective view of the present invention. [Figure 2] FIG. 2 is a perspective view of the exterior of the present invention after the outer shell case has been removed. [Figure 3] FIG. 1 is a top view of the present invention. [Figure 4] FIG. 1 is an exploded perspective view of the present invention. [Figure 5] 1 is an external perspective view showing a clutch unit according to the present invention; [Figure 6] FIG. 2 is an exploded perspective view of the clutch unit of the present invention. [Figure 7] FIG. 4 is an exploded perspective view of the clutch unit of the present invention as viewed from another angle. [Figure 8] FIG. 2 is a schematic cross-sectional side view showing an operating state of the clutch unit of the present invention. [Figure 9] FIG. 2 is a schematic cross-sectional side view showing an operating state of the clutch unit of the present invention. [Figure 10] FIG. 2 is a schematic cross-sectional side view showing an operating state of the clutch unit of the present invention. [Figure 11] FIG. 2 is an enlarged cross-sectional view of a local portion of the clutch unit of the present invention, showing a state in which the first contact portion and the second contact portion are connected so as to contact each other. [Figure 12] 3 is an enlarged cross-sectional view of a portion of the clutch unit of the present invention, showing a state in which the first meshing claws and the second meshing claws are meshed with each other. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] Figures 1 to 4 show a bicycle center-mounted transmission device according to the present invention, and according to these drawings, the bicycle center-mounted transmission device according to the present invention includes an outer shell case 10, an output shaft 20, a motor 30, and a clutch unit 40.

[0011] The outer case 10 has two opposing side surfaces, and the output shaft 20 is installed to pass through both opposing side surfaces of the outer case 10. The output shaft 20 has transmission teeth 21 formed to protrude from its outer circumferential surface, and the transmission teeth 21 is housed within the outer case 10. In this embodiment, the transmission teeth 21 is preferably a helical gear, but is not limited to this. The motor 30 and a clutch unit 40 are housed within the outer case 10, and the output shaft 20 and the motor 30 are connected by the clutch unit 40. In this embodiment, the motor 30 is connected to the clutch unit 40 via a connecting gear set 31, which is composed of a plurality of helical gears, but is not limited to this.

[0012] As shown in FIGS. 4 to 7, the clutch unit 40 includes a drive gear 41, a clutch gear 42, an output gear 43, an operating mechanism 44, a shaft 45, and a bearing 46.

[0013] As shown in FIGS. 4 to 8, the drive gear 41 is connected to the motor 30 and rotates when driven by the motor 30 . The drive gear 41 includes an outer peripheral gear 411 , an inner peripheral gear 412 , and an annular protrusion 413 .

[0014] The outer gear 411 is formed on the outer peripheral surface of the drive gear 41 and is connected to the connecting gear set 31 of the motor 30, and the inner gear 412 is formed on the inner peripheral surface of the drive gear 41. In this embodiment, the drive gear 41 has opposite end surfaces, and the annular protrusion 413 protrudes from the end surface and is formed to surround the rotation center of the drive gear 41, but this is not limited to this, and in other embodiments, the drive gear 41 may not have the annular protrusion 413.

[0015] 6 to 8, 11, and 12, the clutch gear 42 is disposed within the drive gear 41 and is movable relative to the drive gear 41 along the axial direction of the drive gear 41. In this embodiment, the material constituting the clutch gear 42 includes, but is not limited to, a magnetically attractable material. The clutch gear 42 includes a separable tooth portion 421, a plurality of first meshing claws 422, a first connecting portion 423, and a first abutting portion 424.

[0016] The separable teeth portion 421 is formed on the outer peripheral surface of the clutch gear 42 and is connected to mesh with the internal gear 412 of the drive gear 41. With this arrangement, the clutch gear 42 rotates when the drive gear 41 is driven. In this embodiment, the separable teeth portion 421 is preferably a helical gear, but is not limited to this. The clutch gear 42 has opposite end surfaces in the axial direction, and the plurality of first meshing claws 422 are formed on the end surface facing the output gear 43. Specifically, in this embodiment, the first connecting portion 423 is formed to protrude from the clutch gear 42 toward the output gear 43. In other words, the side surface of the first connecting portion 423 facing the output gear 43 is the end surface of the clutch gear 42 facing the output gear 43, and the plurality of first meshing claws 422 are located on the side surface of the first connecting portion 423 facing the output gear 43.

[0017] The plurality of first meshing pawls 422 are formed so as to surround the center of rotation of the clutch gear 42, and the first meshing pawls 422 are connected to each other. As shown in Fig. 12, in this embodiment, the first meshing pawls 422 are ratchet teeth and have a first tooth surface 4221 and a second tooth surface 4222 that are connected to each other, and the first tooth surface 4221 and the second tooth surface 4222 extend in a direction toward the output gear 43 and are inclined in a tangential direction to the rotation direction of the clutch gear 42.

[0018] The first contact portion 424 is formed so as to protrude from the end face of the clutch gear 42 facing the operating mechanism 44. In this embodiment, the first contact portion 424 has a plurality of rib protrusions extending along the radial direction of the clutch gear 42, and these rib protrusions are arranged at intervals in the circumferential direction of the clutch gear 42, but this is not limitative, and the type of the first contact portion 424 can be arbitrarily modified in design as needed.

[0019] Furthermore, in this embodiment, the clutch gear 42 has an extension portion 425 that protrudes from its end face facing the operating mechanism 44 and is formed to surround the center of rotation of the clutch gear 42, and the first abutment portion 424 is arranged on the extension portion 425, but this is not limited to this, and in other embodiments, the clutch gear 42 may not have the extension portion 425.

[0020] 4 to 7 and 12, the output gear 43 is rotatably connected to the output shaft 20 and is detachably connected to the clutch gear 42. With this configuration, the clutch gear 42 can selectively rotate the output gear 43. Furthermore, the output gear 43 includes an output gear portion 431, a plurality of second meshing pawls 432, and a second connecting portion 433.

[0021] The output gear portion 431 is formed on the outer peripheral surface of the output gear 43 and meshes with the transmission teeth portion 21 of the output shaft 20. In this embodiment, the output gear portion 431 is preferably a helical gear, but is not limited to this. The output gear 43 has both end surfaces that face each other in the axial direction, and the plurality of second meshing claws 432 are formed on the end surface facing the clutch gear 42. In this embodiment, the second connecting portion 433 is formed to protrude from the output gear 43 toward the clutch gear 42. In other words, the side surface of the second connecting portion 433 facing the clutch gear 42 is the end surface of the output gear 43 facing the clutch gear 42, and the plurality of second meshing claws 432 are located on the side surface of the second connecting portion 433 facing the clutch gear 42.

[0022] The plurality of second meshing claws 432 are formed so as to surround the rotation center of the output gear 43, and the second meshing claws 432 are connected to one another, and the plurality of second meshing claws 432 can selectively mesh with the first meshing claws 422. In this embodiment, the second meshing claws 432 are ratchet teeth, and the shape of the second meshing claws 432 corresponds to the shape of the first meshing claws 422, but the present invention is not limited to this.

[0023] As shown in Figures 6 to 8 and 11, the operating mechanism 44 is arranged on the side of the clutch gear 42 opposite to the side facing the output gear 43, has magnetic attraction force, and includes a housing 441, an actuator 442, an elastic member 443, a first magnetic member 444, and a second magnetic member 445.

[0024] The housing 441 includes an accommodating space 4411 formed to surround the housing 441, an opening 4412 that communicates with the accommodating space 4411 and faces the clutch gear 42, an inner bottom wall surface 4413 that is located within the accommodating space 4411 and faces the opening 4412, and a first sliding portion 4414 that is formed on the inner bottom wall surface 4413. In this embodiment, a plurality of first sliding portions 4414 are formed on the inner bottom wall surface 4413, and these first sliding portions 4414 are arranged at intervals in the circumferential direction of the inner bottom wall surface 4413. Each first sliding portion 4414 has a groove-like structure that is recessed into the inner bottom wall surface 4413, and has a groove bottom surface 4415 that is inclined with respect to the inner bottom wall surface 4413. Specifically, the groove bottom surface 4415 is inclined in a direction toward the clutch gear 42 along the rotational direction of the clutch gear 42, but is not limited to this, and in other embodiments, the first sliding portion 4414 may not have a groove-shaped structure.

[0025] The actuator 442 is installed in the accommodation space 4411 so as to be movable along the axial direction of the housing 441. In this embodiment, the actuator 442 is a disk-shaped structure made of a magnetically attractable material, but the actuator 442 is not limited to this and the type of the actuator 442 can be arbitrarily designed as needed. The actuator 442 also includes a second contact portion 4421 and a second sliding portion 4422.

[0026] The second abutment portion 4421 is formed on a side surface of the actuator 442 facing the opening 4412, and is in separable abutment with the first abutment portion 424. As a result, when the second abutment portion 4421 and the first abutment portion 424 are connected to each other so as to abut against each other, the clutch gear 42 can rotate the actuator 442. In this embodiment, the second abutment portion 4421 has a plurality of rib protrusions extending along the radial direction of the actuator 442, and these rib protrusions are formed to protrude from the side surface of the actuator 442 facing the clutch gear 42, and are arranged at intervals in the circumferential direction of the actuator 442. On the other hand, since the multiple rib protrusions of the first abutment portion 424 are formed on the side of the clutch gear 42 facing the actuator 442, when the actuator 442 and the clutch gear 42 come into contact, the first abutment portion 424 presses the second abutment portion 4421 in the rotational direction of the clutch gear 42, thereby causing the clutch gear 42 to rotate and drive the actuator 442.

[0027] In addition, in this embodiment, the clutch gear 42 is drilled into the opening 4412 of the housing 441 via the extension portion 425, thereby allowing the clutch gear 42 to move smoothly within the drive gear 41, smoothly perform separation and contact operations with the actuator 442, and reliably perform the abutment and connection operations between the first abutment portion 424 and the second abutment portion 4421.

[0028] The second sliding portion 4422 is formed on a side surface of the actuator 442 facing the inner bottom wall surface 4413, and is slidable relative to the first sliding portion 4414. In this embodiment, the actuator 442 has a plurality of second sliding portions 4422, and the number and positions of these second sliding portions 4422 correspond to the number and positions of the first sliding portions 4414, and each second sliding portion 4422 has a protrusion structure, is housed in the corresponding first sliding portion 4414, and slides while contacting the groove bottom surface 4415 thereof.

[0029] The elastic member 443 is disposed within the storage space 4411 and is installed to abut against the actuator 442 and the periphery of the opening 4412 of the housing 441, thereby forcing the actuator 442 against the inner bottom wall surface 4413.

[0030] In this embodiment, the actuating mechanism 44 includes a first magnetic member 444 disposed around the opening 4412 of the housing 441. Specifically, the actuating mechanism 44 includes a plurality of first magnetic members 444, which are spaced apart around the periphery of the opening 4412, and the arrangement of the first magnetic members 444 enables the actuating mechanism 44 to provide a magnetic attraction force that attracts the clutch gear 42. Similarly, a plurality of second magnetic members 445 are disposed at intervals around the inner bottom wall 4413 of the actuating mechanism 44, and the arrangement of the second magnetic members 445 enables the actuating mechanism 444 to provide a magnetic attraction force that attracts the actuator 442 toward the inner bottom wall 4413. However, the arrangement of these magnetic members is not limited to this.

[0031] 5 to 7, in this embodiment, the clutch unit 40 includes a shaft 45 that is installed to pass through the clutch gear 42, the output gear 43, and the operating mechanism 44, and the clutch gear 42, the output gear 43, and the operating mechanism 44 can each rotate about the shaft 45. More specifically, in this embodiment, the clutch gear 42, the output gear 43, and the actuator 442 of the operating mechanism 44 are coaxially arranged, and the shaft 45 is drilled at the rotation center position of the clutch gear 42, the output gear 43, and the actuator 442, thereby ensuring a predetermined relative positional relationship between the clutch gear 42, the output gear 43, and the actuator 442 and preventing positional deviation during operation, but the present invention is not limited to this, and the shaft 45 may not be provided in other embodiments.

[0032] Furthermore, this embodiment further includes a bearing 46 attached to the drive gear 41; that is, the bearing 46 is mounted on the annular protrusion 413 of the drive gear 41 and supports the drive gear 41 rotatably, thereby preventing misalignment during operation; however, this is not limited to this, and in other embodiments, the bearing 46 may not be provided.

[0033] The operating state of the clutch unit of the present invention will be described below with reference to Figures 8 to 12. As shown in Figure 8, when the motor 30 is not running, the clutch gear 42 is separated from the output gear 43 by the magnetic attractive force of the first magnetic member 444 and is magnetically attracted so as to abut against the actuator 442. Meanwhile, the actuator 442 is pressed against the inner bottom wall surface 4413 by the biasing force of the elastic member 443 so that the second sliding portion 4422 is housed within the first sliding portion 4414.

[0034] 9 and 11, when the motor 30 starts, it rotates the drive gear 41 via the outer gear 411. At this time, the drive gear 41 is supported by the bearing 46 via the annular protrusion 413 and rotates stably within the bearing 46. Furthermore, the drive gear 41 rotates the clutch gear 42 via the inner gear 412. At this time, the first abutment portion 424 of the clutch gear 42 and the second abutment portion 4421 of the actuator 442 are connected so as to abut against each other, so that the actuator 442 also begins to rotate. When the actuator 442 rotates, the second sliding portion 4422 slides along the groove bottom surface 4415 of the first sliding portion 4414, thereby moving the actuator 442 toward the opening 4412 of the housing 441 and, at the same time, moving the clutch gear 42 toward the output gear 43. As shown in Figure 12, the clutch gear 42 moves until the first meshing claw 422 meshes with the second meshing claw 432, causing the output gear 43 to rotate, and the output gear 43 transmits power from the motor 30 to the output shaft 20 through the output gear portion 431 which meshes with the transmission tooth portion 21, thereby assisting the rider in pedaling.

[0035] In this series of operations, the first tooth surface 4221 and the second tooth surface 4222 of each first meshing claw 422 are inclined in the tangential direction to the rotational direction of the clutch gear 42, and therefore when the first meshing claw 422 and the second meshing claw 432 mesh with each other, the clutch gear 42 moves further toward the output gear 43, and as a result, the clutch gear 42 is no longer in contact with the actuator 442. At this time, as shown in Fig. 10, the biasing force of the elastic member 443 and the magnetic attractive force of the second magnetic member 445 return the actuator 442 to the state it was in before the motor 30 was started.

[0036] On the other hand, if the power supply to the motor 30 is stopped or the rotational speed of the clutch gear 42 becomes lower than the rotational speed of the output gear 43 due to some other reason, the first tooth surface 4221 and the second tooth surface 4222 of each first meshing claw 422 are inclined in the tangential direction of the rotational direction of the clutch gear 42, so that the first meshing claw 422 separates from the second meshing claw 432 and the meshed state between them is released.Furthermore, because the first tooth surface 4221 is inclined, when the clutch gear 42 and the output gear 43 begin to separate, the tip portion of the second meshing claw 432 pushes the clutch gear 42 slightly along the first tooth surface 4221 toward the operating mechanism 44, completely separating the clutch gear 42 and the output gear 43. Conversely, unless the rotational speed of the output gear 43 becomes higher than the rotational speed of the clutch gear 42, the meshing state between the first meshing claw 422 and the second meshing claw 432 is maintained, and power from the motor 30 continues to be transmitted to the output gear 43 continuously.

[0037] After the clutch gear 42 and the output gear 43 are separated, the clutch gear 42 is attracted toward the operating mechanism 44 by the magnetic attraction force of the first magnetic member 444 on the operating mechanism 44, and returns to the state before the motor 30 was started, as shown in Figure 8.

[0038] In the center-mounted transmission device for a bicycle of the present invention, when motor 30 begins to output pedaling assist power, actuator 442 in operating mechanism 44 presses clutch gear 42 to engage with output gear 43, but then immediately disengages and returns to its initial position.

[0039] On the other hand, when the motor 30 stops outputting the pedaling assist power, the clutch gear 42 is completely separated from the output gear 43, eliminating continuous contact and preventing wear between the first meshing pawl 422 and the second meshing pawl 432. In this way, by completely separating the clutch gear 42 from the output gear 43, it is possible to prevent the rider from rotating the motor 30 in the opposite direction when pedaling, thereby reducing the rider's physical exertion and also reducing wear on the components, thereby extending the service life.

[0040] Furthermore, by installing the shaft 45, the output gear 43, clutch gear 42 and actuator 442 are all arranged coaxially, ensuring a predetermined relative positional relationship between them, and by installing the bearing 46, the drive gear 41 and clutch gear 42 can be separated and joined smoothly and stably, thereby reducing positional deviation during operation and being able to withstand continuous vibrations caused by pedaling by the rider, and furthermore, the structure of the entire clutch unit 40 can be made more compact.

[0041] The present invention is designed so that the combination of drive gear 41 and clutch gear 42 places the driving member on the outside and the driven member on the inside, thereby efficiently utilizing the limited internal space of the center-mounted motor and increasing space efficiency.In addition, the design of the first connecting portion 423 of clutch gear 42 and the second connecting portion 433 of output gear 43 ensures structural strength while shortening the travel distance of clutch gear 42 and reducing the axial length and overall volume of drive gear 41, thereby making maximum use of the limited internal space of the center-mounted motor.

[0042] In short, the clutch unit 40 of the present invention has a very compact structure, yet is suitable for the narrow internal space of a center-mounted motor, and is designed to withstand the continuous vibrations caused by the rider's pedaling and to prevent misalignment of parts, thereby achieving stable operation. Furthermore, by designing the clutch gear 42 and output gear 43 to be completely separable, the rider can avoid rotating the motor 30 in the opposite direction when the motor 30 stops outputting auxiliary power, thereby reducing physical exertion and wear on the clutch gear 42 and output gear 43. [Explanation of symbols]

[0043] 10 Outer case 20 Output shaft 21 Transmission teeth 30 motor 31 Connecting gear set 40 Clutch unit 41 Drive gear 411 Peripheral gear 412 Internal gear 413 Annular protrusion 42 Clutch gear 421 Separating tooth part 422 First interlocking claw 4221 1st tooth surface 4222 2nd tooth surface 423 1st connection part 424 1st contact part 425 Extension section 43 Output gear 431 Output gear section 432 Second interlocking claw 433 2nd connection part 44 Operating mechanism 441 Housing 4411 Containment Space 4412 Opening 4413 Inner bottom wall 4414 First sliding part 4415 Groove bottom surface 442 Actuator 4421 Second contact part 4422 Second sliding part 443 Elastic Members 444 First magnetic member 445 Second magnetic member 45 shaft 46 Bearings

Claims

1. A center-mounted transmission for a bicycle, comprising: an outer shell case having two opposing side surfaces; an output shaft passing through the two opposing side surfaces of the outer shell case; a motor installed within the outer shell case; and a clutch unit installed within the outer shell case and connecting the output shaft and the motor. the output shaft has transmission teeth formed so as to protrude from its outer circumferential surface, The clutch unit includes a drive gear, a clutch gear, an output gear, and an operating mechanism, of which the drive gear is connected to the motor and driven by the motor, an outer peripheral gear connected to the motor is formed on the outer peripheral surface of the drive gear, and an inner peripheral gear is formed on the inner peripheral surface of the drive gear, The clutch gear is installed within the drive gear so as to be movable along the axial direction of the drive gear, and includes a magnetically attractable material. An engaging and disengaging tooth portion that meshes with an internal gear of the drive gear is formed on an outer circumferential surface of the clutch gear. A plurality of first meshing claws are formed on one end surface of the clutch gear, and the plurality of first meshing claws are formed so as to surround the center of rotation of the clutch gear and are connected to each other. A first abutment portion is formed on the other end surface of the clutch gear. the output gear is rotatably connected to the output shaft and detachably connected to the clutch gear, an output gear portion that meshes with the transmission teeth portion of the output shaft is formed on the outer circumferential surface of the output gear, a plurality of second meshing claws are formed on the end surface of the output gear that faces the clutch gear, the plurality of second meshing claws are formed so as to surround the rotation center of the output gear and are connected to each other, and the plurality of second meshing claws and the plurality of first meshing claws can be selectively meshed with each other, The operating mechanism is arranged on the side of the clutch gear opposite to the side facing the output gear, has a magnetic attraction force, and includes a housing, an actuator, and an elastic member, of which the housing includes an accommodation space formed to surround the clutch gear, an opening facing the clutch gear and communicating with the accommodation space, an inner bottom wall surface located within the accommodation space and facing the opening, and a first sliding part formed on the inner bottom wall surface, the actuator is installed within the accommodation space so as to be movable along the axial direction of the housing, and includes a second abutment part and a second sliding part, a second abutment portion formed on a side surface of the actuator facing the opening and separably abutting against the first abutment portion, the second abutment portion and the first abutment portion being connected so as to abut against each other, thereby causing the clutch gear to rotate the actuator; the second sliding portion formed on a side surface of the actuator facing the inner bottom wall surface and being slidable relative to the first sliding portion; and the elastic member disposed within the storage space and biasing the actuator so as to abut against the periphery of the opening of the housing.

2. 2. The bicycle center-mounted transmission device according to claim 1, wherein the clutch unit includes a shaft that passes through the clutch gear, the output gear, and the operating mechanism, and the clutch gear, the output gear, and the operating mechanism are each rotatable relative to the shaft.

3. 2. The bicycle center-mounted transmission device according to claim 1, wherein the clutch unit includes a bearing attached to the drive gear, the drive gear having an annular protrusion protruding from one end face of the drive gear and formed to surround the center of rotation of the drive gear, and the clutch unit is rotatably supported by the bearing via the annular protrusion.

4. a first connecting portion is formed to protrude from a side of the clutch gear facing an output gear, and the plurality of first engagement claws are arranged on a side surface of the first connecting portion facing the output gear, 2. The bicycle center-mounted transmission device according to claim 1, wherein a second connecting portion is formed to protrude from the output gear toward the clutch gear, and the plurality of second engagement pawls are disposed on a side of the second connecting portion facing the clutch gear.

5. the first sliding portion is a groove-shaped structure formed to be recessed in the inner bottom wall surface, and has a groove bottom surface inclined with respect to the inner bottom wall surface, 5. The bicycle center-mounted transmission device according to claim 1, wherein the second sliding portion has a protruding structure that is housed within the first sliding portion so as to contact the bottom surface of the groove and is slidable along the bottom surface of the groove.

6. 5. A center-mounted transmission device for a bicycle according to claim 1, wherein each of the first and second engaging pawls is a ratchet tooth, and the shape of each of the second engaging pawls corresponds to the shape of each of the first engaging pawls.

7. 7. The bicycle center-mounted transmission device according to claim 6, wherein each of the first engaging pawls has a first tooth surface and a second tooth surface that are connected to each other, the first tooth surface and the second tooth surface extending toward the output gear and inclined in a tangential direction to the rotational direction of the clutch gear.

8. 5. A center-mounted transmission device for a bicycle as described in any one of claims 1 to 4, characterized in that the first abutment portion protrudes from a side of the clutch gear facing the actuator, and the second abutment portion protrudes from a side of the actuator facing the clutch gear, and when the first abutment portion and the second abutment portion are connected so as to abut, the first abutment portion presses against the second abutment portion in the rotational direction of the clutch gear.

9. 5. The bicycle center-mounted transmission device according to claim 1, wherein the actuating mechanism includes a first magnetic member disposed around the opening in the housing.

10. the actuator includes a magnetically attractable material; A center-mounted transmission device for a bicycle as described in any one of claims 1 to 4, characterized in that a second magnetic member is installed on the inner bottom wall surface of the operating mechanism, and the actuator is attracted by the magnetic attraction force of the second magnetic member.

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