Drive unit and electric vehicle

Abstract

To miniaturize a drive unit.SOLUTION: A drive unit 20 for use in an electric vehicle, comprises: a motor 40 including a rotor 42 having an opening at a rotation center thereof; a housing 31 that accommodates the motor 40; a crankshaft 30 rotatably attached to the housing 31; a sprocket that outputs a rotational force of the motor 40; and a power transmission mechanism 50 that decelerates or accelerates a rotational force of the motor 40 and transmits the rotational force to the sprocket. The power transmission mechanism 50 includes at least one gear provided with a tooth portion on a surface thereof. The rotor 42 and the tooth portion are disposed at positions overlapping each other in an axial direction of the crankshaft 30. At least a portion of the gear is disposed inside the opening.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a drive unit and an electric vehicle equipped with the drive unit. [Background technology]

[0002] BACKGROUND ART Conventionally, a drive unit that includes a motor and a power transmission mechanism that transmits the rotational force of the motor to a sprocket has been known as a drive unit used in an electric vehicle (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7246001 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a demand for miniaturization of drive units. In Patent Document 1, the motor included in the drive unit and the circuit board connected to the motor are arranged close to each other to thereby miniaturize the drive unit. However, conventional technologies including Patent Document 1 still have room for improvement in terms of miniaturization of the drive unit. [Means for solving the problem]

[0005] A drive unit according to one aspect of the present disclosure is a drive unit used in an electric vehicle, and comprises: a motor including a rotor with an opening at its center of rotation; a housing that accommodates the motor; a crankshaft rotatably attached to the housing; a sprocket that outputs the rotational force of the motor; and a power transmission mechanism that slows or speeds up the rotational force of the motor and transmits it to the sprocket, wherein the power transmission mechanism includes at least one gear having teeth on its surface, the rotor and the teeth are positioned so as to overlap in the axial direction of the crankshaft, and at least a portion of the gear is positioned inside the opening.

[0006] Furthermore, a drive unit that is one aspect of the present disclosure is a drive unit used in an electric vehicle, and comprises: a motor including a rotor with an opening at its center of rotation; a housing that accommodates the motor; a crankshaft that is rotatably attached to the housing and rotatable by manual driving force; a first sprocket that outputs the rotational force of the motor; a second sprocket that outputs the rotational force of the manual driving force; and a power transmission mechanism that slows down or speeds up the rotational force of the motor and transmits it to the first sprocket, wherein the power transmission mechanism includes at least one gear with teeth on its surface, the rotor and the teeth are positioned so as to overlap in the axial direction of the crankshaft, and at least a portion of the gear is positioned inside the opening.

[0007] Furthermore, a drive unit that is one aspect of the present disclosure is a drive unit used in an electric vehicle, and comprises: a motor including a rotor with an opening at its center of rotation; a housing; a crankshaft rotatably attached to the housing; a sprocket that outputs the rotational force of the motor; and a power transmission mechanism that slows down or speeds up the rotational force of the motor and transmits it to the sprocket, wherein the power transmission mechanism includes at least one gear with teeth on its surface, the rotor and the teeth are positioned so as to overlap in the axial direction of the crankshaft, and the rotational axis of the rotor and the rotational axis of the crankshaft are arranged coaxially.

[0008] Furthermore, a drive unit that is one aspect of the present disclosure is a drive unit used in an electric vehicle, and includes a motor, a housing that accommodates the motor, a crankshaft rotatably attached to the housing, a sprocket that outputs the rotational force of the motor, a power transmission mechanism that slows down or speeds up the rotational force of the motor and transmits it to the sprocket, and a rotation detection unit that detects the rotation of the crankshaft or a member that rotates integrally with the crankshaft, wherein the rotation detection unit rotates integrally with the crankshaft.

[0009] Furthermore, a drive unit according to one aspect of the present disclosure is a drive unit used in an electric vehicle, comprising: a motor; a housing that accommodates the motor; a crankshaft rotatably attached to the housing; a sprocket that outputs the rotational force of the motor; and a power transmission mechanism that slows or speeds up the rotational force of the motor and transmits it to the sprocket, wherein the motor includes a motor shaft that is an output shaft, a stator fixed to the housing, and a rotor that is fixed to the motor shaft and has a magnet, the rotor being positioned to face the stator in a direction along the rotational axis of the motor shaft, and the power transmission mechanism includes at least one gear having teeth on its surface, and the stator and the teeth are positioned to overlap in the axial direction of the crankshaft. [Effects of the Invention]

[0010] The drive unit according to the present disclosure can be made smaller. Despite its small size, the drive unit according to the present disclosure exhibits sufficient output characteristics as a drive source for an electric vehicle. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing the appearance of an electrically assisted bicycle according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view of the drive unit of the first embodiment. [Figure 3] FIG. 2 is a cross-sectional view of the drive unit of the first embodiment, showing an enlarged view of the vicinity of the motor. [Figure 4] FIG. 2 is a cross-sectional view of a one-way clutch that constitutes the drive unit of the first embodiment. [Figure 5] FIG. 10 is a cross-sectional view of a drive unit according to a second embodiment. [Figure 6] FIG. 10 is a cross-sectional view of a drive unit according to a second embodiment, showing an enlarged view of the vicinity of a motor. [Figure 7] FIG. 10 is a cross-sectional view of a drive unit according to a third embodiment. [Figure 8] FIG. 10 is a cross-sectional view of a drive unit according to a third embodiment, showing an enlarged view of the vicinity of a motor. [Figure 9] FIG. 10 is a cross-sectional view of a drive unit according to a fourth embodiment. [Figure 10] FIG. 10 is a cross-sectional view of a drive unit according to a fourth embodiment, showing an enlarged view of the vicinity of a motor. [Figure 11] FIG. 10 is a cross-sectional view of a drive unit according to a fifth embodiment. [Figure 12] FIG. 10 is a cross-sectional view of a drive unit according to a fifth embodiment, showing an enlarged view of the vicinity of a motor. [Figure 13] FIG. 13 is a cross-sectional view of a drive unit according to a sixth embodiment. [Figure 14] FIG. 13 is a cross-sectional view of a drive unit according to a seventh embodiment. [Figure 15] FIG. 13 is a cross-sectional view of a drive unit according to a seventh embodiment, showing an enlarged view of the vicinity of the motor. [Figure 16] FIG. 13 is a cross-sectional view of a drive unit according to an eighth embodiment. [Figure 17] FIG. 13 is a cross-sectional view of a drive unit according to an eighth embodiment, showing an enlarged view of the vicinity of the motor. [Figure 18] FIG. 13 is a cross-sectional view of a drive unit according to a ninth embodiment. [Figure 19] FIG. 23 is a cross-sectional view of a drive unit according to a tenth embodiment. [Figure 20] FIG. 23 is a cross-sectional view of a drive unit according to an eleventh embodiment. [Figure 21]FIG. 23 is a cross-sectional view of a drive unit according to an eleventh embodiment, showing an enlarged view of the vicinity of the motor. [Figure 22] FIG. 23 is a cross-sectional view of a drive unit according to a twelfth embodiment. [Figure 23] FIG. 23 is a cross-sectional view of a drive unit according to a twelfth embodiment, showing an enlarged view of the vicinity of the motor. DETAILED DESCRIPTION OF THE INVENTION

[0012] The following describes in detail embodiments of the drive unit and the electric vehicle equipped with the drive unit according to the present disclosure. The embodiments described below are merely examples, and the present disclosure is not limited to the following embodiments. Furthermore, the present disclosure also includes configurations that selectively combine multiple embodiments and modified examples described below.

[0013] [First embodiment] A first embodiment of a drive unit and an electric vehicle according to the present disclosure will be described below with reference to FIGS.

[0014] FIG. 1 is a right side view showing the appearance of an electrically assisted bicycle 1, which is an electric vehicle according to a first embodiment. The electrically assisted bicycle of the present disclosure is not limited to the electrically assisted bicycle 1, but may be any electrically assisted vehicle that runs on the power of a motor. Furthermore, the electrically assisted bicycle 1 of the present disclosure is not limited to a sports bicycle as shown in FIG. 1, but may be, for example, a city bicycle or a folding bicycle. Hereinafter, the terms "front / back," "left / right," and "up / down" in the embodiments of the present disclosure refer to the front / back, left / right, and up / down directions based on a state in which a rider is seated on the saddle 5 of the electrically assisted bicycle 1 facing the handlebars 4.

[0015] As shown in FIG. 1, the electrically assisted bicycle 1 includes a frame 2, a front wheel 3A, a rear wheel 3B, a handlebar 4, and a saddle 5, similar to a typical bicycle.

[0016] The frame 2 is a framework that connects a front wheel 3A, a rear wheel 3B, a handlebar 4, a saddle 5, etc. The frame 2 is made up of multiple pipes, including a head pipe 2A, a front fork 2B, a top pipe 2C, a down pipe 2D, a seat pipe 2E, a seat stay 2F, and a chain stay 2G.

[0017] The electrically assisted bicycle 1 further includes a drive unit 20 and a power storage device 10 that supplies power to the drive unit 20. The electrically assisted bicycle 1 has the function of assisting the driving force (human-powered driving force) generated by the pedaling force of the rider with the power of a motor 40 of the drive unit 20 (see FIG. 2 described below).

[0018] As will be described in detail later, a portion of the drive unit 20 is housed inside the down pipe 2D. Note that the drive unit 20 may be attached to the outside of the frame 2 without being housed inside the down pipe 2D.

[0019] The drive unit 20 includes a pair of crank arms 6, each with a pedal 7 attached. One crank arm 6 is provided on each side of the electrically assisted bicycle 1. The other ends of the pair of crank arms 6 are connected to each other by a crank shaft 30 (see FIG. 2).

[0020] The drive unit 20 also includes a sprocket 70. The electrically assisted bicycle 1 includes a chain 8 as a mechanism for transmitting the rotational force of the sprocket 70 to the rear wheel 3B. The chain 8 connects the sprocket 70 to a rear wheel sprocket 11 provided on the rear wheel 3B. The sprocket 70 and the rear wheel sprocket 11 may also be connected by a belt or shaft drive.

[0021] The power storage device 10 is a power supply device that supplies power to the drive unit 20. In the example shown in FIG. 1 , the power storage device 10 is attached to the outside of the down pipe 2D. The position of the power storage device 10 is not limited to the down pipe 2D, and the power storage device 10 may be attached to the top pipe 2C or the seat pipe 2E. The power storage device 10 may also be housed inside the frame 2.

[0022] It is preferable to use a secondary battery as the battery housed in the power storage device 10, but a primary battery may also be used. The voltage of the power storage device 10 is, for example, 12 V or more, 48 V. The power storage device 10 may also be provided with a voltage conversion circuit. The voltage conversion circuit may be provided inside the power storage device 10 or may be provided outside the power storage device 10.

[0023] Next, the drive unit 20 of the first embodiment will be described with reference to Fig. 2. Fig. 2 is a cross-sectional view of the drive unit 20.

[0024] 2, the drive unit 20 has a motor 40 that applies a rotational force to assist the pedal force of the pedal 7 (see FIG. 1), a housing 31 that accommodates the motor 40, and a crankshaft 30 that is rotatably attached to the housing 31. The drive unit 20 is a so-called center unit type drive unit.

[0025] The drive unit 20 further includes a human power transmission body 61 that is attached to rotate integrally with the crankshaft 30 and rotates by human driving force, an output body 62 that outputs the rotational force of the motor 40, a sprocket 70 that outputs the rotational force of the output body 62, and a power transmission mechanism 50 that reduces the rotational force of the motor 40 and transmits it to the sprocket 70 via the output body 62.

[0026] As will be described in detail later, the output body 62 functions as a combiner body that combines the rotational force due to the manual drive force and the rotational force of the motor 40. In this embodiment, the power transmission mechanism 50 is composed of a two-stage reduction mechanism, and includes a planetary gear mechanism (first power transmission mechanism) 51 that is the first-stage reduction mechanism, and a second reduction mechanism (second power transmission mechanism) 52 that is the second-stage reduction mechanism.

[0027] 2, the motor 40 includes a stator 41, a rotor 42, and a motor shaft 43 that rotates integrally with the rotor 42. In this embodiment, the motor 40 is an inner rotor type motor. The motor 40 is accommodated in the housing 31 as described above.

[0028] The stator 41 is fixed inside the housing 31 by press fitting, adhesive, or pins. The rotor 42 has an annular shape with a circular opening 44 (see FIG. 3) at the center of rotation, and is disposed inside the stator 41. As will be described in detail later, a sun gear 511, an internal gear 512, a planetary gear 513, and a planetary gear shaft 514, which are gears that constitute the planetary gear mechanism 51, are disposed radially inside the opening 44.

[0029] The motor shaft 43 is the output shaft of the motor 40, and is disposed so that its rotation axis is aligned with the axial direction of the crankshaft 30. The motor shaft 43 is rotatably supported relative to the housing 31 by bearings 320, 321, and 322 provided inside the housing 31. The rotor 42 and the motor shaft 43 are fixed together by, for example, serrations.

[0030] The housing 31 is a member that constitutes the outer shell of the drive unit 20. The housing 31 is mainly made of a metal such as aluminum, stainless steel, or magnesium, but a non-metal may also be used, and the material of the housing 31 is not particularly limited.

[0031] The housing 31 includes a first divided body 311 that constitutes the right half of the housing 31, and a second divided body 312 that constitutes the left half of the housing 31. The first divided body 311 and the second divided body 312 are joined together with fastening members 34 such as bolts. By joining the first divided body 311 and the second divided body 312, the hollow housing 31 is formed. Note that the size, shape, thickness, etc. of the housing 31 are not particularly limited. Furthermore, the space formed inside the housing 31 may or may not be sealed.

[0032] The first divided body 311 has a protruding portion 3111 that protrudes to the left. An internal gear 512 that constitutes the planetary gear mechanism 51 is fitted into the protruding portion 3111.

[0033] In addition to the motor 40, the housing 31 accommodates a power transmission body 61, a part of the output body 62, the planetary gear mechanism 51, and the second reduction mechanism 52. The housing 31 also has through holes 314 and 315 at both ends, through which the crankshaft 30 passes.

[0034] In this embodiment, a portion of the housing 31 is housed inside the down pipe 2D. A heat dissipation member 33 that transfers heat from the housing 31 to the down pipe 2D is disposed between the housing 31 and the down pipe 2D (frame 2). That is, the heat from the housing 31 is transferred to the down pipe 2D via the heat dissipation member 33. Generally, the temperature of the housing 31 tends to rise due to heat from the motor 40 and other components housed in the housing 31. By disposing the heat dissipation member 33 between the housing 31 and the down pipe 2D as in this embodiment, the temperature of the housing 31 can be lowered, thereby improving the reliability of the drive unit 20. Note that the heat from the housing 31 may be transferred via the heat dissipation member 33 to a component other than the down pipe 2D.

[0035] The heat dissipation member 33 may be, for example, a compressible elastic body having a higher thermal conductivity than general resin. One example of a suitable heat dissipation member 33 is a heat dissipation sheet made of flexible resin and thermally conductive filler dispersed in the resin. The thickness of the heat dissipation member 33 is, for example, 0.3 mm or more and 2 mm or less. Conventionally known materials may be used for the heat dissipation member 33.

[0036] The heat dissipation member 33 may be adhesive and may be attachable to the surface of the housing 31 or the down pipe 2D, etc. If the heat dissipation member 33 is attachable to the surface of the housing 31 or the down pipe 2D, etc., the heat dissipation member 33 can be easily installed. The heat dissipation member 33 may be attached to the surface of the housing 31 or the down pipe 2D, etc., using an adhesive, adhesive tape, etc.

[0037] The crankshaft 30 is a cylindrical member that is rotationally driven by a manual drive force. The crankshaft 30 rotates relative to the drive unit 20. In this embodiment, the crankshaft 30 is made of a hollow member, but it may also be made of a solid member.

[0038] Both ends of the crankshaft 30 protrude outward from the housing 31, and a pair of crank arms 6 (see FIG. 1) are provided on each end of the crankshaft 30. The crankshaft 30 is rotatably supported with respect to the housing 31 (frame 2) by bearings 324 and 325. The bearings 324 and 325 are formed, for example, by ball bearings.

[0039] The power transmission mechanism 50 is a mechanism that reduces the speed of the rotational force of the motor 40 and transmits the rotational force of the motor 40 to the sprocket 70 via the output body 62. In this embodiment, the power transmission mechanism 50 is composed of a two-stage reduction mechanism and includes a planetary gear mechanism 51 that is the first-stage reduction mechanism and a second reduction mechanism 52 that is the second-stage reduction mechanism. Note that the power transmission mechanism 50 may also include a speed-up mechanism.

[0040] As will be described in detail later, the planetary gear mechanism 51 has the motor shaft 43 as a sun gear 511, an internal gear 512 arranged concentrically with the sun gear 511, planetary gears 513 meshing with the sun gear 511 and the internal gear 512, a planetary gear shaft 514, and a planet carrier 515 as an output shaft. The internal gear 512 is fitted into a protrusion 3111 of the housing 31, and is thereby fixed non-rotatably relative to the housing 31. The rotational force of the motor 40 output from the planet carrier 515 is transmitted to the second reduction mechanism 52 via the one-way clutch 53.

[0041] When a rotational force is applied to the planetary carrier 515 in a direction that accelerates the power-assisted bicycle 1 in the direction of travel (hereinafter referred to as the "forward direction"), the one-way clutch 53 transmits this rotational force to the first transmission gear 521 that constitutes the second reduction mechanism 52. Furthermore, when a rotational force is applied to the planetary carrier 515 in a direction opposite to the forward direction, the one-way clutch 53 does not transmit this rotational force to the first transmission gear 521. Furthermore, when a rotational force in the forward direction is applied to the first transmission gear 521, the one-way clutch 53 does not transmit this rotational force to the planetary carrier 515.

[0042] The second reduction gear mechanism 52 has a first transmission gear 521 and a second transmission gear 522. The rotation axis of the first transmission gear 521 is positioned coaxially with the rotation axis of the sun gear 511, and the rotation axis of the second transmission gear 522 is positioned coaxially with the rotation axis of the crankshaft 30. In other words, the outer diameter of the second transmission gear 522 is larger than the outer diameter of the first transmission gear 521. In addition, the number of teeth of the second transmission gear 522 is larger than the number of teeth of the first transmission gear 521.

[0043] The first transmission gear 521 is disposed radially outside the planetary carrier 515, and the rotational force of the motor 40 is transmitted to the first transmission gear 521 via a one-way clutch 53. The first transmission gear 521 is rotatably supported with respect to the housing 31 by a bearing 323 (first bearing).

[0044] The second transmission gear 522 meshes with teeth provided on the outer circumferential surface of the output body 62. As a result, the rotational force of the motor 40 transmitted to the second transmission gear 522 is transmitted to the output body 62.

[0045] Here, the bearing 323 (first bearing) that rotatably supports the first transmission gear 521 and the one-way clutch 53 are arranged at positions that overlap in the axial direction of the crankshaft 30. This makes it easy to reduce the size of the drive unit 20.

[0046] In addition, the second reduction gear mechanism 52 and the bearing 320 (second bearing) that is provided at the tip (right end) of the motor shaft 43 as the sun gear 511 and rotatably supports the motor shaft 43 are arranged at positions that overlap in the axial direction of the crankshaft 30. This makes it easy to reduce the size of the drive unit 20.

[0047] In this embodiment, the second reduction gear mechanism 52 is configured by two gears, the first transmission gear 521 and the second transmission gear 522, but the number of gears may be one, or three or more. Also, the power transmission mechanism 50 may be a one-stage reduction mechanism, or a three- or more-stage reduction mechanism.

[0048] The power transmission body 61 is a cylindrical member extending along the axial direction of the crankshaft 30, and is disposed on the outer periphery of the crankshaft 30 inside the housing 31. The power transmission body 61 rotates integrally with the crankshaft 30. In this embodiment, the power transmission body 61 is divided into a first power transmission body 611 and a second power transmission body 612. Note that the power transmission body 61 may be formed from a single member.

[0049] The first power transmission body 611 is connected to the crankshaft 30. The inner peripheral surface of the first power transmission body 611 is formed with splines or serrations that fit with the crankshaft 30. Note that a portion where the first power transmission body 611 and the crankshaft 30 fit together may be provided with missing teeth. This allows for positioning in the assembly direction and facilitates assembly. The first power transmission body 611 and the crankshaft 30 may also be fitted together by press-fitting or screws.

[0050] The second power transmission body 612 is disposed to the right of the first power transmission body 611 in the axial direction of the crankshaft 30. The second power transmission body 612 is connected to the first power transmission body 611 and transmits rotational force to the output body 62.

[0051] In this embodiment, the outer peripheral surface of the right end of the first power transmission body 611 is formed with splines or serrations that mate with the inner peripheral surface of the left end of the second power transmission body 612. This connects the first power transmission body 611 and the second power transmission body 612.

[0052] The lengths of the first and second manual power transmission members 611 and 612 in the axial direction of the crankshaft 30 are not particularly limited as long as they can transmit the rotational force of the manual driving force to the output member 62, and are, for example, 5% to 40% of the axial length of the crankshaft 30, respectively. In this embodiment, the length of the first manual power transmission member 611 in the axial direction of the crankshaft 30 is longer than the length of the second manual power transmission member 612. Note that the length of the first manual power transmission member 611 in the axial direction of the crankshaft 30 may be shorter than the length of the second manual power transmission member 612.

[0053] The output body 62 is a cylindrical member extending along the axial direction of the crankshaft 30, and is disposed on the outer periphery of the crankshaft 30. The rotation axis of the output body 62 is positioned coaxially with the rotation axis of the crankshaft 30.

[0054] The length of the output body 62 in the axial direction of the crankshaft 30 is shorter than the length of the crankshaft 30, for example, 10% to 50% of the axial length of the crankshaft 30. The right end of the output body 62 passes through a through-hole 314 provided in the housing 31 and protrudes to the outside of the housing 31. The output body 62 is rotatably supported with respect to the housing 31 by a bearing 324.

[0055] The output body 62 has an outer peripheral surface provided with teeth that mesh with the teeth of the second transmission gear 522. As a result, the rotational force of the motor 40 is transmitted to the output body 62 via the second transmission gear 522.

[0056] In this embodiment, a one-way clutch 63 is provided between the second power transmission body 612 and the output body 62. When a rotational force in the forward direction is applied to the second power transmission body 612, the one-way clutch 63 transmits the rotational force to the output body 62. When a rotational force in the opposite direction to the forward direction is applied to the second power transmission body 612, the one-way clutch 63 does not transmit the rotational force to the output body 62. When a rotational force in the forward direction is applied to the output body 62 via the power transmission mechanism 50, the one-way clutch 63 does not transmit the rotational force to the second power transmission body 612. The one-way clutch 63 also functions as a bearing and rotatably supports the output body 62. The configuration of the one-way clutch 63 will be described later.

[0057] A spline or serration that fits with the sprocket 70 is formed on the portion of the output body 62 that protrudes outside the housing 31. This allows the sprocket 70 to rotate integrally with the output body 62. Note that an elastic member may be disposed between the output body 62 and the sprocket 70 to restrict movement of the sprocket 70.

[0058] In this embodiment, the human power transmission body 61 and the output body 62 are provided separately, but they may also be configured as an integrated unit. For example, it is possible to provide only the output body 62 without providing the human power transmission body 61. In this case, the rotational force of the crankshaft 30 caused by the human driving force is transmitted to the output body 62, thereby moving the electrically assisted bicycle 1 forward.

[0059] A one-way clutch may be disposed between the output body 62 and the sprocket 70. When a rotational force in the forward direction is applied to the output body 62, the one-way clutch transmits the rotational force to the sprocket 70. When a rotational force in the direction opposite to the forward direction is applied to the output body 62, the one-way clutch does not transmit the rotational force to the sprocket 70.

[0060] Here, the power transmission path in the drive unit 20 will be described. First, the power transmission path of the human-powered driving force applied to the pedals 7 will be described. When the rider pedals 7 of the power-assisted bicycle 1, the crankshaft 30 rotates in the forward direction. When the crankshaft 30 rotates in the forward direction, the human-power transmission body 61, which fits onto the outer periphery of the crankshaft 30, rotates in the forward direction together with the crankshaft 30. The rotational force of the human-power transmission body 61 rotating in the forward direction is then transmitted to the output body 62, which outputs the rotational force of the motor 40. The output body 62 and the sprocket 70 fixed to the output body 62 then rotate in the forward direction together. When the sprocket 70 rotates in the forward direction, a rotational force in the forward direction is applied to the rear wheel sprocket 11 via the chain 8, causing the rear wheel sprocket 11 and the rear wheel 3B to rotate in the forward direction. This moves the power-assisted bicycle 1 forward.

[0061] Next, the power transmission path of the rotational force of motor 40 will be described. When motor shaft 43 of motor 40 rotates in the forward direction, the rotational force is transmitted to output body 62 via power transmission mechanism 50, which includes planetary gear mechanism 51 and second reduction mechanism 52. In other words, output body 62 functions as a combiner body that combines the rotational force from human power transmission body 61 due to the aforementioned manual driving force with the rotational force of motor 40. The rotational force of motor 40 transmitted to output body 62 is transmitted to rear wheel 3B via the same power transmission path as the aforementioned manual driving force, and the electrically assisted bicycle 1 moves forward.

[0062] The drive unit 20 includes a torque detector 80 that detects the torque of the manual driving force, and a control board 81 on which a control device (not shown) is mounted to control the output of the motor 40 according to the detected torque and realize an appropriate electric assist function. The drive unit 20 also includes a rotation detector 82 that detects the rotation of the crankshaft 30.

[0063] The torque detection unit 80 is provided on the outer periphery of the first power transmitting body 611 and detects strain applied to the first power transmitting body 611. For example, a strain sensor that detects physical strain or a strain sensor that detects magnetic strain can be used as the torque detection unit 80. Alternatively, for example, a paint that emits light in response to a mechanical stimulus can be applied to the outer periphery of the power transmitting body 611, and the light can be detected by an optical sensor.

[0064] In this embodiment, the drive unit 20 has two torque detectors 80, one on each side, at positions facing each other in the circumferential direction on the outer periphery of the first power transmission body 611. Only one torque detector 80 may be provided on the outer periphery of the first power transmission body 611, or three or more torque detectors 80 may be provided. Furthermore, the installation location of the torque detector 80 is not limited to the outer periphery of the first power transmission body 611, and it may also be located on the outer periphery of the second power transmission body 612 or the crankshaft 30, for example.

[0065] The control device is disposed on a control board 81, and controls the rotation of the motor 40 based on the torque detected by the torque detection unit 80. The control device also controls the rotation of the motor 40 based on the detection information of the rotation detection unit 82. The control device may be configured in a conventional manner.

[0066] Communication between the torque detection unit 80 and the rotation detection unit 82 and the control device may be performed using signal lines or wireless signals. When communication is performed using wireless signals, cables connecting the torque detection unit 80 and the rotation detection unit 82 and the control device are not required, making it easier to reduce the size of the drive unit 20.

[0067] In this embodiment, the control board 81 is made up of a single board having through holes through which the crankshaft 30 and the motor 40 pass. The control boards 81 are each arranged so that the direction approximately normal to the surface (thickness direction) is aligned with the axial direction of the crankshaft 30. Note that the control board 81 may be made up of multiple boards.

[0068] A portion of the control board 81 is joined to the motor 40. By joining a portion of the control board 81 to the motor 40 and arranging the control board 81 and the motor 40 close to each other, the cable connecting the control board 81 and the motor 40 can be shortened, making it easier to make the drive unit 20 smaller.

[0069] A portion of the control board 81 is joined to the second divided body 312. In this embodiment, the control board 81 and the second divided body 312 are joined via a heat dissipation member 35. The heat dissipation member 35 may have the same configuration as the heat dissipation member 33 interposed between the housing 31 and the down pipe 2D.

[0070] The control board 81 may be provided with, for example, a rotor rotation detection unit 85 for detecting the rotation of the rotor 42. The rotor rotation detection unit 85 has, for example, a Hall element. The Hall element detects fluctuations in the magnetic field caused by the rotation of the rotor 42, thereby measuring the rotation speed of the rotor 42. Note that the magnetic force detected by the Hall element may be the magnetic force of a member that rotates together with the rotor 42.

[0071] A cable 83 extending from the outside of the drive unit 20 is connected to the control board 81 via a connector 84. The connector 84 is separate from the drive unit 20. The cable 83 is connected to, for example, the power storage device 10 (see FIG. 1 ) and supplies power to electronic devices arranged on the control board 81.

[0072] Here, the connector 84 includes a first portion 841 that extends substantially normal to the surface of the control board 81, and a second portion 842 that extends in a direction inclined relative to the substantially normal to the surface of the control board 81. In this embodiment, the second portion 842 is configured to be substantially perpendicular to the first portion 841. In other words, the connector 84 is bent substantially perpendicularly. This allows the length of the connector 84 in the left-right direction to be shortened, and the drive unit 20 to be made more compact.

[0073] The rotation detector 82 detects the rotation speed of the crankshaft 30. The rotation detector 82 has, for example, a built-in Hall element and is disposed at a position overlapping with the magnet 86 provided on the outer periphery of the first power transmitting body 611. The Hall element detects fluctuations in the magnetic field of the magnet caused by the rotation of the crankshaft 30, thereby measuring the rotation speed of the crankshaft 30. Note that the configuration of the rotation detector 82 is not limited to this. The rotation detector 82 may be, for example, an inertial sensor such as an acceleration sensor or a gyro sensor.

[0074] In this embodiment, the rotation detector 82 is arranged on the control board 81. By arranging the rotation detector 82 on the control board 81, the rotation detector 82 can be arranged without increasing the number of boards, which makes it easier to reduce the size of the drive unit 20.

[0075] Next, the motor 40 and the gears that make up the planetary gear mechanism 51 will be described in detail with further reference to Fig. 3. Fig. 3 is an enlarged view of the vicinity of the motor 40 in Fig. 2.

[0076] As shown in FIG. 3, the motor 40 includes a stator 41, a rotor 42, and a motor shaft 43 that rotates integrally with the rotor 42.

[0077] The stator 41 is fixed inside the housing 31 by press-fitting, adhesive, screwing, or pins. In this case, an elastic member such as a rubber member or urethane may be provided between the stator 41 and the housing 31. By providing an elastic member, vibration of the stator 41 can be reduced. Also, a heat dissipation sheet or heat dissipation paste (thermal grease, heat dissipation gel, etc.) may be provided between the stator 41 and the housing 31. This improves the heat dissipation of the motor 40 and suppresses overheating and vibration of the motor 40.

[0078] The outer diameter of the stator 41 is preferably 100 mm or less, and more preferably 90 mm or less. Setting the outer diameter of the stator 41 to 100 mm or less makes it easier to further reduce the size of the drive unit 20. The lower limit of the outer diameter of the stator 41 is, for example, 60 mm.

[0079] The rotor 42 has an annular shape with a circular opening 44 at its center of rotation, and is disposed inside the stator 41. The inner diameter of the rotor 42 is preferably 30 mm or more, and more preferably 40 mm or more. By making the inner diameter of the rotor 42 30 mm or more, it becomes easy to dispose the gears that constitute the planetary gear mechanism 51 radially inside the opening 44 of the rotor 42. The upper limit of the inner diameter of the rotor 42 is, for example, 100 mm.

[0080] The motor shaft 43 is a cylindrical shaft member that extends along the axial direction (left-right direction) of the crankshaft 30, and rotates integrally with the rotor 42. The motor shaft 43 is disposed so that its rotation axis is along the axial direction of the crankshaft 30. The motor shaft 43 is rotatably supported relative to the housing 31 by bearings 320, 321, and 322 provided inside the housing 31.

[0081] The rotor 42 and the motor shaft 43 are fixed together by serrations. The rotor 42 and the motor shaft 43 may also be fixed together by press fitting, shrink fitting, cold fitting, or the like. When fixing the rotor 42 and the motor shaft 43 together, an elastic member such as a rubber member or urethane may be provided between the rotor 42 and the motor shaft 43.

[0082] The motor shaft 43 is disposed so that its central axis of rotation passes through the center of an internal gear 512 that constitutes the planetary gear mechanism 51, which will be described later, and passes through the internal gear 512. In addition, a toothed portion 43A that meshes with a toothed portion 513A of a planetary gear 513 that constitutes the planetary gear mechanism 51 is provided on the surface of the motor shaft 43. The motor shaft 43 constitutes a sun gear 511 of the planetary gear mechanism 51. Note that the toothed portion in this specification refers to the tooth profile provided on the surface of a gear, and also includes an area that does not mesh with the toothed portion of another gear.

[0083] As shown in FIG. 3, the planetary gear mechanism 51 has a motor shaft 43 as a sun gear 511, an internal gear 512 arranged concentrically with the sun gear 511, planetary gears 513 meshing with the sun gear 511 and the internal gear 512, a planetary gear shaft 514, and a planetary carrier 515 as an output shaft.

[0084] The internal gear 512 has an annular shape, and teeth 512A are formed over the entire inner circumferential surface. The internal gear 512 is fitted into a protrusion 3111 of the housing 31, and is thereby fixed to the housing 31 so as not to be rotatable.

[0085] The planetary gear 513 has teeth 513A formed along its entire circumference and meshes with the sun gear 511 and the internal gear 512, respectively. The planetary gear shaft 514 passes through the center of the planetary gear 513 and rotatably supports the planetary gear 513. A bushing 38 having an L-shape in an axial cross section is disposed radially outward of the planetary gear shaft 514, allowing the planetary gear shaft 514 to rotate. Note that the bushing 38 alone may be provided without providing the bearing 323. The planetary carrier 515 supports the planetary gear 513 so that it can revolve freely. The rotation axis of the planetary carrier 515 is coaxial with the rotation axis of the sun gear 511. The planetary carrier 515 is rotatably supported by a bearing 323 provided in the housing 31. The bearing 323 is, for example, a ball bearing.

[0086] 3, the rotor 42, the teeth 43A of the motor shaft 43 (sun gear 511), the teeth 512A of the internal gear 512, and the teeth 513A of the planetary gear 513 are arranged at positions that overlap with each other in the axial direction of the crankshaft 30. This allows the drive unit 20 to be made smaller in size in the axial direction of the crankshaft 30. Note that the teeth 43A of the motor shaft 43 (sun gear 511), the teeth 512A of the internal gear 512, and the teeth 513A of the planetary gear 513 may be arranged at positions that overlap with the stator 41 in the axial direction of the crankshaft 30, instead of with the rotor 42. In this case, the drive unit 20 can also be made smaller.

[0087] Furthermore, at least a portion of the teeth 43A of the motor shaft 43, the teeth 512A of the internal gear 512, and the teeth 513A of the planetary gear 513 are arranged radially inside the opening 44 of the rotor 42. This allows the drive unit 20 to be further miniaturized.

[0088] Metal gears and resin gears can be used for the gears that make up the planetary gear mechanism 51. Using resin gears can reduce the weight of the drive unit 20 and also reduce noise during driving. Examples of resin materials that can be used include polyacetal, nylon 46, nylon 66, PEEK, thermosetting resin, and super engineering plastics.

[0089] The gears that make up the planetary gear mechanism 51 may be spur gears or helical gears. By using helical gears, noise during running can be reduced. Furthermore, it is preferable that the gears that make up the planetary gear mechanism 51 are lubricated with grease. Note that the gears that make up the planetary gear mechanism 51 may also be lubricated with lubricating oil. Furthermore, each gear may have a non-circular arc shape that imitates the shape of a gear.

[0090] Next, the one-way clutch 63 will be described with further reference to Figure 4. Figure 4 is a cross-sectional view of the one-way clutch 63.

[0091] 2, the one-way clutch 63 is disposed between the second power transmission member 612 and the output member 62. In addition, the one-way clutch 63 is disposed closer to the sprocket 70 than the axial center of the crankshaft 30 in the axial direction. As described above, when a rotational force in the forward direction is applied to the second power transmission member 612, the one-way clutch 63 transmits this rotational force to the output member 62. In addition, when a rotational force in the direction opposite to the forward direction is applied to the second power transmission member 612, the one-way clutch 63 does not transmit this rotational force to the output member 62.

[0092] As shown in Fig. 4, the one-way clutch 63 includes an inner race 63A and an outer race 63B that covers the outer periphery of the inner race 63A. The inner race 63A is provided on the outer periphery of the second human power transmission body 612. The inner race 63A may be formed integrally with the second human power transmission body 612. The outer race 63B is provided on the inner periphery of the output body 62. The outer race 63B may be formed integrally with the output body 62.

[0093] Sprags 63C are disposed between the inner race body 63A and the outer race body 63B as engaging elements. In other words, the one-way clutch 63 is a so-called sprag-type one-way clutch. The sprags 63C are stretched between the inner race body 63A and the outer race body 63B, thereby enabling the transmission of rotational force. On the other hand, the sprags 63C slide between the inner race body 63A and the outer race body 63B, thereby preventing the transmission of rotational force. The shape of the sprags 63C is not limited to the form shown in FIG. 4 and may be, for example, cylindrical.

[0094] Balls 64D are further disposed between the inner race 63A and the outer race 63B as rolling elements. Therefore, when the outer race 63B is rotatable relative to the inner race 63A, that is, when rotational force cannot be transmitted, the one-way clutch 63 receives the radial load, functions as a bearing, and rotatably supports the second power transmission body 612. In the example shown in FIG. 4, the one-way clutch 63 includes four balls 64D, which are arranged at approximately equal intervals in the circumferential direction. The rolling elements are not limited to balls 64D, and may be cylindrical members.

[0095] [Second embodiment] Next, a second embodiment of the drive unit of the present disclosure will be described with reference to Figures 5 and 6. Figure 5 is a cross-sectional view of drive unit 20A of the second embodiment, and Figure 6 is an enlarged view of the vicinity of motor 40A in Figure 5. Below, the same reference numerals are used for components common to the first embodiment, and redundant explanations will be omitted, and differences from the first embodiment will mainly be described.

[0096] 5, the drive unit 20A has a motor 40A that applies a rotational force to assist the pedal force on the pedal 7, a housing 31 that accommodates the motor 40A, and a crankshaft 30 that is rotatably attached to the housing 31. The drive unit 20A is a so-called center unit type drive unit, similar to the drive unit 20 of the first embodiment.

[0097] Furthermore, similar to the drive unit 20 of the first embodiment, the drive unit 20A is attached so as to rotate integrally with the crankshaft 30 and further includes a human power transmission body 61 that rotates by human driving force, an output body 62 that outputs the rotational force of the motor 40A, a sprocket 70 that outputs the rotational force of the output body 62, and a power transmission mechanism 50 that reduces the rotational force of the motor 40A and transmits it to the sprocket 70 via the output body 62.

[0098] 6, the motor 40A of the drive unit 20A of the second embodiment is a so-called outer rotor type motor in which a rotor 42A is disposed radially outside a stator 41A. By using an outer rotor type motor, it becomes easier to output high torque compared to an inner rotor type motor.

[0099] 6, rotor 42A, toothed portion 43A of motor shaft 43, toothed portion 512A of internal gear 512, and toothed portion 513A of planetary gear 513 are arranged in overlapping positions in the axial direction of crankshaft 30. This allows drive unit 20A to be made smaller in size in the axial direction of crankshaft 30 even when an outer rotor type motor is used.

[0100] [Third embodiment] Next, a third embodiment of the drive unit of the present disclosure will be described with reference to Figures 7 and 8. Figure 7 is a cross-sectional view of drive unit 20B of the third embodiment, and Figure 8 is an enlarged view of the vicinity of motor 40 in Figure 7. Below, the same reference numerals are used for components common to the first embodiment, and redundant explanations will be omitted, and differences from the first embodiment will mainly be described.

[0101] As shown in FIG. 7, the drive unit 20B, like the drive unit 20 of the first embodiment, has a motor 40 that applies a rotational force to assist the force applied to the pedal 7, a housing 31 that accommodates the motor 40, and a crankshaft 30 rotatably attached to the housing 31.

[0102] Drive unit 20B further includes a human power transmission body 61 that is attached to rotate integrally with crankshaft 30 and rotates by human driving force, an output body 62 that outputs the rotational force of motor 40, a sprocket 70 that outputs the rotational force of output body 62, and a power transmission mechanism 50B that reduces the rotational force of motor 40 and transmits it to sprocket 70 via output body 62. Power transmission mechanism 50B is composed of a two-stage reduction mechanism and includes a planetary gear mechanism 51 that is a first-stage reduction mechanism and a second reduction mechanism 52 that is a second-stage reduction mechanism.

[0103] 8, the configuration of the planet carrier 515B that constitutes the planetary gear mechanism 51 is different from the planet carrier 515 of the drive unit 20 of the first embodiment. Specifically, the planet carrier 515B has a hollow portion 5151 at the center of the rotation axis, and the protruding member 36 and the bearing 326 are arranged in the hollow portion 5151.

[0104] The protruding member 36 is fitted into a recess 3112 formed in the first divided body 311, and is fixed so as not to rotate relative to the first divided body 311. There are no particular limitations on the material that makes up the protruding member 36, but it is made of, for example, a metal material whose main component is iron or aluminum. Providing the protruding member 36 can stabilize the rotation of the planet carrier 515B.

[0105] The bearing 326 rotatably supports the planet carrier 515B relative to the housing 31. By providing the bearing 326 in the hollow portion 5151 of the planet carrier 515B, the drive unit 20 can be made smaller.

[0106] [Fourth embodiment] Next, a fourth embodiment of the drive unit of the present disclosure will be described with reference to Figures 9 and 10. Figure 9 is a cross-sectional view of a drive unit 20C of the fourth embodiment, and Figure 10 is an enlarged view of the vicinity of the motor 40 in Figure 9. Below, the same reference numerals are used for components common to the first embodiment, and redundant explanations will be omitted, and differences from the first embodiment will mainly be described.

[0107] As shown in Figure 9, the drive unit 20C, like the drive unit 20 of the first embodiment, has a motor 40 that applies rotational force to assist the force applied to the pedal 7, a housing 31 that accommodates the motor 40, and a crankshaft 30 rotatably attached to the housing 31.

[0108] The drive unit 20C further includes a human power transmission body 61 that is attached to rotate integrally with the crankshaft 30 and rotates by human driving force, an output body 62 that outputs the rotational force of the motor 40, a sprocket 70 that outputs the rotational force of the output body 62, and a power transmission mechanism 50C that reduces the rotational force of the motor 40 and transmits it to the sprocket 70 via the output body 62. The power transmission mechanism 50C is composed of a two-stage reduction mechanism and includes a planetary gear mechanism 51 that is a first-stage reduction mechanism and a second reduction mechanism 52 that is a second-stage reduction mechanism.

[0109] As shown in FIG. 10, the power transmission mechanism 50C of the drive unit 20C includes an output member 516 that meshes with a planet carrier 515C that constitutes the output shaft of the planetary gear mechanism 51. The output member 516 is a solid cylindrical member that extends along the axial direction of the crankshaft 30. The output member 516 is arranged so that the rotation axis of the output member 516 is positioned coaxially with the rotation axis of the planet carrier 515C. The provision of the output member 516 makes it possible to stabilize the rotation of the planet carrier 515C.

[0110] A convex portion 5161 that protrudes radially outward from the output member 516 is formed around the entire circumference of the output member 516 at the axial center of the output member 516. The output member 516 and the planet carrier 515C mesh together in the region to the left of the convex portion 5161. In other words, the output member 516 and the planet carrier 515C do not mesh together in the region to the right of the convex portion 5161.

[0111] The output member 516 has a small diameter portion 5162 formed in a region to the right of the protrusion 5161, the small diameter portion 5162 having a smaller diameter than the other portions. A bearing 327 (third bearing) that rotatably supports the output member 516 with respect to the housing 31 is disposed radially outward of the small diameter portion 5162. This allows the output member 516 to be rotatably supported with respect to the housing 31 without increasing the size of the drive unit 20C. Furthermore, the bearing 327 (third bearing) and the first transmission gear 521 are disposed at positions where they overlap in the axial direction of the crankshaft 30. This makes it easy to reduce the size of the drive unit 20C.

[0112] [Fifth embodiment] Next, a fifth embodiment of the drive unit of the present disclosure will be described with reference to Figures 11 and 12. Figure 11 is a cross-sectional view of a drive unit 20D of the fifth embodiment, and Figure 12 is an enlarged view of the vicinity of a motor 40D in Figure 11. Below, the same reference numerals will be used for components common to the fourth embodiment, and redundant explanations will be omitted, and differences from the fourth embodiment will mainly be described.

[0113] 11, the drive unit 20D has a motor 40D that applies a rotational force to assist the pedal force on the pedal 7, a housing 31 that accommodates the motor 40D, and a crankshaft 30 that is rotatably attached to the housing 31. The drive unit 20D is a so-called center unit type drive unit, similar to the drive unit 20C of the fourth embodiment.

[0114] Furthermore, like the drive unit 20C of the fourth embodiment, the drive unit 20D is attached so as to rotate integrally with the crankshaft 30 and further includes a human power transmission body 61 that rotates by human driving force, an output body 62 that outputs the rotational force of the motor 40A, a sprocket 70 that outputs the rotational force of the output body 62, and a power transmission mechanism 50C that reduces the rotational force of the motor 40D and transmits it to the sprocket 70 via the output body 62.

[0115] On the other hand, as shown in FIG. 12 , the drive unit 20D of the fifth embodiment differs from the drive unit 20C of the fourth embodiment in the configuration of the motor 40D. Specifically, the motor 40D includes a motor shaft 43D, which is an output shaft, a stator 41D fixed to the housing 31, and a rotor 42D fixed to the motor shaft 43D and having a magnet 45D. The rotor 42D is disposed to face the stator 41D in the direction along the rotation axis of the motor shaft 43D. In other words, the motor 40D is a so-called axial gap motor. By using an axial gap motor, the motor 40D can be made smaller than an inner rotor type or outer rotor type motor, making it easier to make the drive unit 20D smaller.

[0116] In this embodiment, the rotor 42D is disposed on only one side (the left side) of the stator 41D in the direction along the rotation axis of the motor shaft 43D. This allows the motor 40D to be made smaller, making it easier to make the drive unit 20D smaller. Note that the rotor 42D may also be disposed on both sides of the stator 41D in the direction along the rotation axis of the motor shaft 43D.

[0117] The motor shaft 43D is rotatably supported by bearings 320 and 321 relative to the housing 31. The bearings 320 and 321 are spaced apart from each other in the direction along the rotation axis of the motor shaft 43D.

[0118] 12, the stator 41D, the toothed portion 43A of the motor shaft 43D, the toothed portion 512A of the internal gear 512, and the toothed portion 513A of the planetary gear 513 are arranged in overlapping positions in the axial direction of the crankshaft 30. This allows the drive unit 20D to be made smaller in size in the axial direction of the crankshaft 30 even when an axial gap motor is used.

[0119] [Sixth embodiment] Next, a sixth embodiment of the drive unit of the present disclosure will be described with reference to Fig. 13. Fig. 13 is a cross-sectional view of a drive unit 20E according to the second embodiment. Below, the same reference numerals will be used for configurations common to the first embodiment, and duplicated explanations will be omitted, with differences from the first embodiment being mainly described.

[0120] As shown in FIG. 13, the drive unit 20E has a motor 40 that applies a rotational force to assist the pedal force on the pedal 7, a housing 31E that accommodates the motor 40, and a crankshaft 30 that is rotatably attached to the housing 31E.

[0121] Furthermore, similar to the drive unit 20 of the first embodiment, the drive unit 20E further includes a human power transmission body 61 that is attached to rotate integrally with the crankshaft 30 and rotates by human driving force, an output body 62 that outputs the rotational force of the motor 40, a sprocket 70 that outputs the rotational force of the output body 62, and a power transmission mechanism 50 that reduces the rotational force of the motor 40 and transmits it to the sprocket 70 via the output body 62.

[0122] The housing 31E includes a first divided body 311E that forms the right outer shell of the housing 31E, a second divided body 312E that forms the left outer shell of the housing 31E, and a third divided body 313E that is sandwiched between the first divided body 311E and the second divided body 312E. The first divided body 311E and the third divided body 313E are joined by fastening members 341 such as bolts, and the second divided body 312E and the third divided body 313E are joined by fastening members 342 such as bolts. By constructing the housing 31E from three divided bodies, the construction of each divided body can be simplified and productivity can be improved. The number of divided bodies that constitute the housing may be four or more. Furthermore, the space formed inside the housing 31E may be sealed or not sealed.

[0123] The third divided body 313E has a protruding portion 3131 that protrudes to the left. An internal gear 512 that constitutes the planetary gear mechanism 51 is fitted into the protruding portion 3131.

[0124] [Seventh embodiment] Next, a seventh embodiment of the drive unit of the present disclosure will be described with reference to Figures 14 and 15. Figure 14 is a cross-sectional view of a drive unit 20F of the seventh embodiment, and Figure 15 is an enlarged view of the vicinity of the motor 40 in Figure 14. Below, the same reference numerals will be used for components common to the first embodiment, and duplicate explanations will be omitted, and differences from the first embodiment will mainly be described.

[0125] 14, the drive unit 20F has a motor 40 that applies a rotational force to assist the pedal force of the pedal 7, a housing 31F that accommodates the motor 40, and a crankshaft 30 that is rotatably attached to the housing 31F. Similar to the housing 31E of the fifth embodiment, the housing 31F is composed of three divided bodies, a first divided body 311F, a second divided body 312F, and a third divided body 313F.

[0126] The drive unit 20F further includes a human power transmission body 61 that is attached to rotate integrally with the crankshaft 30 and rotates by human driving force, an output body 62 that outputs the rotational force of the motor 40, a sprocket 70 that outputs the rotational force of the output body 62, and a power transmission mechanism 50F that reduces the rotational force of the motor 40 and transmits it to the sprocket 70 via the output body 62. The power transmission mechanism 50F is composed of a two-stage reduction mechanism and includes a planetary gear mechanism 51F that is the first-stage reduction mechanism and a second reduction mechanism 52 that is the second-stage reduction mechanism.

[0127] As shown in FIG. 15, the planetary gear mechanism 51F has a motor shaft 43 as a sun gear 511F, an internal gear 512F arranged concentrically with the sun gear 511F and as an output shaft, a planetary gear 513F meshing with the sun gear 511F and the internal gear 512F, respectively, and a planetary gear shaft 514F as a fixed shaft.

[0128] The internal gear 512F has an annular shape and includes an annular portion 5121 having teeth formed on its inner circumferential surface to mesh with the planetary gear 513F, a connecting portion 5122 connected to the annular portion 5121 and extending radially inward, and a tubular portion 5123 connected to the connecting portion 5122 and extending along the axial direction of the crankshaft 30. The annular portion 5121, the connecting portion 5122, and the tubular portion 5123 rotate integrally.

[0129] The rotational force of the motor 40 is transmitted to a first transmission gear 521 constituting the second reduction gear mechanism 52 via the cylindrical portion 5123. A one-way clutch 53 is provided between the cylindrical portion 5123 and the first transmission gear 521.

[0130] The planetary gear shaft 514F is fitted into a recess 3132 provided in the third divided body 313F. This prevents the planetary gear shaft 514F from rotating relative to the housing 31F. In the example shown in FIGS. 14 and 15, the planetary gear shaft 514F is fixed to the third divided body 313F, but the planetary gear shaft 514F may be fixed to the second divided body 312F. In the example shown in FIGS. 14 and 15, the housing 31F is made up of three divided bodies, but it may also be made up of two divided bodies.

[0131] [Eighth embodiment] Next, an eighth embodiment of a drive unit according to the present disclosure will be described with reference to Figures 16 and 17. Figure 16 is a cross-sectional view of a drive unit 20G according to the eighth embodiment, and Figure 17 is an enlarged view of the vicinity of the motor 40 in Figure 16. Below, the same reference numerals will be used for components common to the first embodiment, and redundant explanations will be omitted, and differences from the first embodiment will mainly be described.

[0132] As shown in Figure 16, the drive unit 20G, like the drive unit 20 of the first embodiment, has a motor 40 that applies rotational force to assist the force applied to the pedal 7, a housing 31 that accommodates the motor 40, and a crankshaft 30 rotatably attached to the housing 31.

[0133] The drive unit 20G further includes a human power transmission body 61 that is attached to rotate integrally with the crankshaft 30 and rotates by human driving force, an output body 62 that outputs the rotational force of the motor 40, a sprocket 70 that outputs the rotational force of the output body 62, and a power transmission mechanism 50G that reduces the rotational force of the motor 40 and transmits it to the sprocket 70 via the output body 62.

[0134] 17, the power transmission mechanism 50G is a parallel-shaft gear mechanism having a first transmission gear 541 that meshes with the motor shaft 43, which is the output shaft of the motor 40, and whose rotation axis is arranged parallel to the rotation axis of the motor shaft 43. The power transmission mechanism 50G has the first transmission gear 541, a gear shaft 542, and a second transmission gear 543, and is a mechanism that transmits the rotational force of the motor 40 to the output body 62 via the first transmission gear 541, the gear shaft 542, and the second transmission gear 543.

[0135] The first transmission gear 541 is disposed radially inside the opening of the rotor 42. The first transmission gear 541 has teeth 541A that mesh with teeth 43A provided on the motor shaft 43. The rotor 42, the teeth 43A of the motor shaft 43, and the teeth 541A of the first transmission gear 541 are disposed in positions that overlap in the axial direction of the crankshaft 30. This allows the drive unit 20G to be made smaller in the axial direction of the crankshaft 30. In addition, splines or serrations that engage with the gear shaft 542 are formed on the inner circumferential surface of the first transmission gear 541. The first transmission gear 541 may be insert-molded onto the gear shaft 542.

[0136] The gear shaft 542 is disposed along the axial direction of the crankshaft 30. The gear shaft 542 rotates integrally with the first transmission gear 541. The length of the gear shaft 542 is not particularly limited, but is, for example, 5% to 50% of the axial length of the crankshaft 30. In addition, a tooth portion 542A is formed on the right end side of the gear shaft 542.

[0137] The second transmission gear 543 meshes with a toothed portion 542A formed on the right end side of the gear shaft 542. The rotation axis of the second transmission gear 543 is positioned coaxially with the rotation axis of the crankshaft 30.

[0138] A one-way clutch 53G is provided between the second transmission gear 543 and the output body 62. That is, the rotational force of the motor 40 output from the second transmission gear 543 is transmitted to the output body 62 via the one-way clutch 53G.

[0139] When a rotational force in the forward direction is applied to the second transmission gear 543, the one-way clutch 53G transmits this rotational force to the output body 62. When a rotational force in the direction opposite to the forward direction is applied to the second transmission gear 543, the one-way clutch 53G does not transmit this rotational force to the output body 62. When a rotational force in the forward direction is applied to the output body 62 via the human power transmission body 61, the one-way clutch 53G does not transmit this rotational force to the second transmission gear 543.

[0140] [Ninth embodiment] Next, a ninth embodiment of a drive unit of the present disclosure will be described with reference to Fig. 18. Fig. 18 is a cross-sectional view of a drive unit 20H of the ninth embodiment. In the following, the same reference numerals will be used for configurations common to the first embodiment, and duplicated explanations will be omitted, and differences from the first embodiment will mainly be described.

[0141] As shown in FIG. 18, the drive unit 20H has a motor 40H that applies a rotational force to assist the pedal force on the pedal 7, a housing 31H that accommodates the motor 40H, and a crankshaft 30 that is rotatably attached to the housing 31H.

[0142] The drive unit 20H further includes a human power transmission body 61H that is attached to rotate integrally with the crankshaft 30 and rotates by human driving force, an output body 62H that outputs the rotational force of the motor 40H, a sprocket 70 that outputs the rotational force of the output body 62H, and a power transmission mechanism 50H that reduces the rotational force of the motor 40H and transmits it to the sprocket 70 via the output body 62H.

[0143] The motor 40H includes a stator 41H and a rotor 42H having an opening at the center of rotation. In this embodiment, the motor 40H does not include a motor shaft that rotates integrally with the rotor 42H. The motor 40H may be an outer rotor type or an axial gap type motor. The motor 40H is formed with a recess 46H into which a planetary gear shaft 504H that constitutes a power transmission mechanism 50H (described later) fits.

[0144] Similar to the first embodiment, the housing 31H includes a first divided body 311H that constitutes the right half of the housing 31H and a second divided body 312H that constitutes the left half of the housing 31H. The first divided body 311H and the second divided body 312H are joined together with fastening members 34 such as bolts. The inner surface of the first divided body 311H is formed with splines or serrations that mate with a first internal gear 5021H that constitutes the power transmission mechanism 50H, which will be described later. The first divided body 311H and the first internal gear 5021H may be engaged with each other using screws.

[0145] The power transmission mechanism 50H is a planetary gear mechanism including an internal gear 502H, a planetary gear 503H, and a planetary gear shaft 504H. The power transmission mechanism 50H reduces the rotational force of the motor 40H and transmits it to the sprocket 70 via the output body 62H. In this embodiment, the planetary gear 503H is a stepped planetary gear including two gears with different outer diameters.

[0146] The internal gear 502H includes a first internal gear 5021H and a second internal gear 5022H. The first internal gear 5021H meshes with a large diameter portion of the planetary gear 503H, and the second internal gear 5022H meshes with a small diameter portion of the planetary gear 503H.

[0147] The first internal gear 5021H is fitted into the inner surface of the first divided body 311H that constitutes the housing 31H, and is thereby fixed so as not to be rotatable relative to the housing 31H. In other words, the first internal gear 5021H functions as a fixed shaft of the planetary gear mechanism.

[0148] On the other hand, the second internal gear 5022H functions as an output shaft of the planetary gear mechanism, and the rotational force of the second internal gear 5022H is transmitted to the output body 62H via the one-way clutch 53H. The second internal gear 5022H is rotatably supported with respect to the housing 31H by a bearing 320H.

[0149] As described above, the planetary gear 503H is a stepped planetary gear including two gears with different outer diameters. The planetary gear shaft 504H passes through the center of the planetary gear 503H and rotatably supports the planetary gear 503H. The left end of the planetary gear shaft 504H is fitted into a recess 46H formed in the motor 40H. This allows the planetary gear shaft 504H to rotate integrally with the motor 40H. The planetary gear 503H does not have to be stepped and may be composed of a single gear. In this case, the outer and inner diameters of the first internal gear 5021H and the second internal gear 5022H are approximately the same, but the number of teeth of each gear can be changed by making the addendum shift coefficients of the gear specifications different. This configuration simplifies the shape of the planetary gear 503H and improves the assembly ease of the drive unit 20H.

[0150] The power transmission body 61H is a cylindrical member extending along the axial direction of the crankshaft 30, and is disposed inside the housing 31H on the outer periphery of the crankshaft 30. The power transmission body 61H rotates integrally with the crankshaft 30. In this embodiment, the power transmission body 61H is formed of a single member, but may be formed of a plurality of members, as in the first embodiment.

[0151] The output body 62H is a cylindrical member extending along the axial direction of the crankshaft 30 and is disposed on the outer periphery of the crankshaft 30. The rotational axis of the output body 62H is coaxial with the rotational axis of the crankshaft 30. The output body 62H is rotatably supported relative to the housing 31H by bearings 321H and 322H. A reduction gear system such as the drive unit 20H of this embodiment tends to have poor power transmission efficiency and generate heat at low rotational speeds. Therefore, oil lubrication is preferable to facilitate heat dissipation. Oil lubrication reduces the friction coefficient of the gear tooth surface and suppresses heat generation. Furthermore, oil lubrication allows oil to circulate around the housing 31H, enabling efficient heat dissipation from the housing 31H. Furthermore, oil application to the motor 40H also allows the motor 40H to efficiently dissipate heat.

[0152] [Tenth embodiment] Next, a tenth embodiment of the drive unit of the present disclosure will be described with reference to Fig. 19. Fig. 19 is a cross-sectional view of a drive unit 20J of the tenth embodiment. Below, the same reference numerals will be used for configurations common to the first embodiment, and duplicated explanations will be omitted, and differences from the first embodiment will mainly be described.

[0153] As shown in FIG. 19, the drive unit 20J has a motor 40J that applies a rotational force to assist the pedal force on the pedal 7, a housing 31J that accommodates the motor 40J, and a crankshaft 30 that is rotatably attached to the housing 31J.

[0154] The drive unit 20J also includes an output body 62J that outputs the rotational force of the motor 40H, a sprocket 70 that outputs the rotational force of the output body 62J, and a power transmission mechanism 50J that reduces the speed of the rotational force of the motor 40J and transmits it to the sprocket 70 via the output body 62J. The drive unit 20J does not include a power transmission body, and the rotational force of the crankshaft 30 is transmitted directly to the output body 62J. By not including a power transmission body, the components that make up the power transmission mechanism 50J can be located closer to the crankshaft 30, making it easier to reduce the size of the drive unit 20J.

[0155] The motor 40J includes a stator 41J and a rotor 42J having an opening at its rotation center. In this embodiment, the motor 40J does not include a motor shaft that rotates integrally with the rotor 42J. The motor 40J may be an outer rotor type motor or an axial gap type motor. The motor 40J is formed with a recess 46J into which a planetary gear shaft 504J that constitutes a power transmission mechanism 50J (described later) fits.

[0156] Similar to the first embodiment, the housing 31J includes a first divided body 311J constituting the right half of the housing 31J and a second divided body 312J constituting the left half of the housing 31J. The first divided body 311J and the second divided body 312J are joined by fastening members 34 such as bolts. The inner surface of the first divided body 311J is formed with splines or serrations that mate with a first internal gear 5021J constituting the power transmission mechanism 50J (described later). The first divided body 311J also has a partition wall 3111J extending toward the crankshaft 30. The partition wall 3111J abuts against the radially outer side of the bearing 322J and holds the bearing 322J. The partition wall 3111J may be formed of a component (e.g., an insulator) of the stator 41J.

[0157] The interior of the housing 31J is divided by a partition wall 3111J. The motor 40J and the power transmission mechanism 50J are disposed in the space to the right of the partition wall 3111J, and the control board 81J is disposed in the space to the left of the partition wall 3111J. Lubricating oil is contained in the space to the right of the partition wall 3111J. This lubricates the gears that make up the power transmission mechanism 50J, improving durability and quietness. Note that no lubricating oil is provided in the space where the control board 81J is disposed.

[0158] From the viewpoint of suppressing leakage of the lubricating oil contained in the space to the right of the partition wall 3111J, it is preferable to provide an elastic member such as an O-ring between the stator 41J and the housing 31J (first segment 311J). It is also preferable to provide an oil seal 37J on the outer periphery of the crankshaft 30. In this case, it is preferable to provide a bushing 38J made of a metal such as iron between the oil seal 37J and the motor 40J. This makes it possible to suppress leakage of the lubricating oil contained in the space to the right of the partition wall 3111J while suppressing wear caused by contact of the lip portion of the oil seal 37J with the motor 40J.

[0159] The power transmission mechanism 50J is a planetary gear mechanism including an internal gear 502J, a planetary gear 503J, and a planetary gear shaft 504J. The power transmission mechanism 50J reduces the rotational force of the motor 40J and transmits it to the sprocket 70 via the output body 62J. In this embodiment, the planetary gear 503J is a stepped planetary gear including two gears with different outer diameters.

[0160] The internal gear 502J includes a first internal gear 5021J and a second internal gear 5022J. The first internal gear 5021J meshes with a large diameter portion of the planetary gear 503J, and the second internal gear 5022J meshes with a small diameter portion of the planetary gear 503J.

[0161] The first internal gear 5021J is fitted into the inner surface of a first divided body 311J that constitutes the housing 31J, and is thereby fixed so as not to be rotatable relative to the housing 31J. In other words, the first internal gear 5021J functions as a fixed shaft of the planetary gear mechanism.

[0162] On the other hand, the second internal gear 5022J functions as an output shaft of the planetary gear mechanism, and the rotational force of the second internal gear 5022J is transmitted to the output body 62J via the one-way clutch 53J. The second internal gear 5022J is rotatably supported with respect to the housing 31J by a bearing 320J.

[0163] As described above, the planetary gear 503J is a stepped planetary gear including two gears with different outer diameters. The planetary gear shaft 504J passes through the center of the planetary gear 503J and rotatably holds the planetary gear 503J. The left end of the planetary gear shaft 504J is fitted into a recess 46J formed in the motor 40J. This allows the planetary gear shaft 504J to rotate integrally with the motor 40J. The bearing provided between the planetary gear 503J and the planetary gear shaft 504J may be a ball bearing or a plain bearing.

[0164] The output body 62J is a cylindrical member extending along the axial direction of the crankshaft 30 and is disposed on the outer periphery of the crankshaft 30. The rotation axis of the output body 62J is positioned coaxially with the rotation axis of the crankshaft 30. In this embodiment, as described above, no human power transmission body is provided. Therefore, the rotational force of the crankshaft 30 is transmitted to the output body 62J via the one-way clutch 63J. The one-way clutch 63J also functions as a bearing and rotatably supports the output body 62J.

[0165] The drive unit 20J is provided with a plurality of strain sensors 80J (e.g., two to four) as torque detectors. The strain sensors 80J are disposed radially outward of the bearing 321J and measure the load acting on the bearing 321J. The bearing 321J supports the crankshaft 30 on the opposite side of the crankshaft 30 from the side where the sprocket 70 is disposed in the axial direction of the crankshaft 30, and is therefore less susceptible to the influence of chain tension. This allows the strain sensors 80J to perform accurate detection. The control board 81J is also provided with a rotation detector 82J that detects the rotation of the crankshaft 30. The rotation detector 82J may, for example, incorporate a Hall element and be positioned so as to overlap a magnet 86J disposed on the outer periphery of the crankshaft 30. The Hall element detects fluctuations in the magnetic field of the magnet 86J due to the rotation of the crankshaft 30, thereby measuring the rotation speed of the crankshaft 30. The configuration of the rotation detector 82J is not limited to this.

[0166] [Eleventh embodiment] Next, an eleventh embodiment of the drive unit of the present disclosure will be described with reference to Figures 20 and 21. Figure 20 is a cross-sectional view of drive unit 120 of the eleventh embodiment, and Figure 21 is an enlarged view of the vicinity of motor 140 in Figure 20. Below, the same reference numerals are used for configurations common to the first embodiment, and redundant explanations will be omitted, and differences from the first embodiment will mainly be described.

[0167] As shown in FIG. 20, the drive unit 120 has a motor 140 that applies a rotational force to assist the force applied to the pedal 7, a housing 131 that accommodates the motor 140, and a crankshaft 130 that is rotatably attached to the housing 131.

[0168] The drive unit 120 is attached to rotate integrally with the crankshaft 130 and includes a human power transmission body 161 that rotates due to human-powered driving force, a first output body 162 that outputs the rotational force of the motor 140, and a second output body 163 that outputs the rotational force due to the human-powered driving force. The drive unit 120 also includes a first sprocket 171 that outputs the rotational force of the first output body 162, a second sprocket 172 that outputs the rotational force of the second output body 163, and a planetary gear mechanism 150 as a power transmission mechanism that reduces the rotational force of the motor 140 and transmits it to the first sprocket 171 via the first output body 162. In other words, the first sprocket 171 outputs the rotational force of the motor 140, and the second sprocket 172 outputs the rotational force of the human-powered driving force.

[0169] The motor 140 includes a stator 141, a rotor 142, and a motor shaft 143 that rotates integrally with the rotor 142. In this embodiment, the motor 140 is an inner rotor type motor. However, the motor 140 may also be an outer rotor type motor.

[0170] The rotor 142 has an annular shape with a circular opening 144 (see FIG. 21) at the center of rotation, and is disposed inside the stator 141. Disposed radially inside the opening 144 are a sun gear 1501, an internal gear 1502, a planetary gear 1503, and a planetary gear shaft 1504, which are gears that constitute the planetary gear mechanism 150.

[0171] The rotor 142 and the motor shaft 143 are fixed together by serrations. The rotor 142 and the motor shaft 143 may also be fixed together by press fitting, shrink fitting, cold fitting, or the like. When fixing the rotor 142 and the motor shaft 143 together, an elastic member such as a rubber member or urethane may be provided between the rotor 142 and the motor shaft 143.

[0172] Motor shaft 143 is a cylindrical shaft member that extends in the left-right direction and rotates integrally with rotor 142. Motor shaft 143 is disposed so that its rotation axis is aligned with the axial direction of crankshaft 130. Motor shaft 143 is rotatably supported relative to housing 131 by bearings 1320, 1321, and 1322 provided within housing 131.

[0173] 21 , the motor shaft 143 is disposed so that its central axis of rotation passes through the center of the internal gear 1502 that constitutes the planetary gear mechanism 150, and passes through the internal gear 1502. In addition, a toothed portion 143A that meshes with a toothed portion 1503A of the planetary gear 1503 that constitutes the planetary gear mechanism 150 is provided on the surface of the motor shaft 143. The motor shaft 143 constitutes the sun gear 1501 of the planetary gear mechanism 150.

[0174] The size, shape, etc. of the motor 140 can be appropriately adopted from the size, shape, etc. of the motor 40 of the first embodiment.

[0175] The housing 131 is a member that constitutes the outer shell of the drive unit 120, and houses the motor 140. The housing 131 is mainly made of a metal such as aluminum or stainless steel, but a non-metal may also be used, and the material of the housing 131 is not particularly limited.

[0176] The housing 131 includes a first divided body 1311 that constitutes the right half of the housing 131, and a second divided body 1312 that constitutes the left half of the housing 131. The first divided body 1311 and the second divided body 1312 are joined together by fastening members 134 such as bolts. By joining the first divided body 1311 and the second divided body 1312, the hollow housing 131 is formed. Note that the size, shape, thickness, etc. of the housing 131 are not particularly limited. Furthermore, the space formed inside the housing 131 may or may not be sealed.

[0177] The first divided body 1311 has a protruding portion 13111 that protrudes to the left. An internal gear 1502 that constitutes the planetary gear mechanism 150 is fitted into the protruding portion 13111.

[0178] A plurality of grooves 1312A are formed in the wall surface of second divided body 1312. This increases the area of ​​the portion of second divided body 1312 that is in contact with the outside air. As a result, the temperature of housing 131 can be lowered, improving the reliability of drive unit 120. Note that instead of or in addition to the wall surface of second divided body 1312, grooves may be formed in the wall surface of first divided body 1311.

[0179] In addition to the motor 140, the housing 131 accommodates the human power transmission body 161, a portion of the first output body 162, a portion of the second output body 163, and the planetary gear mechanism 150. The housing 131 also has through holes 1314 and 1315 through which the crankshaft 130 passes. The housing 131 also has a through hole 1316 through which the first output body 162 passes.

[0180] In this embodiment, the housing 131 is attached to the outside of the frame 2, but similar to the housing 31 of the first embodiment, it may be housed inside the frame 2. When the housing 131 is housed inside the frame 2, a heat dissipation member that transfers heat from the housing 131 to the frame 2 may be arranged between the housing 131 and the frame 2.

[0181] The crankshaft 130 is a cylindrical member that is rotated by manual driving force. The crankshaft 130 may be made of a hollow member or a solid member.

[0182] A pair of crank arms (not shown) are provided on both ends of the crankshaft 130. Both ends of the crankshaft 130 protrude outward from the housing 131. The crankshaft 130 is rotatably supported with respect to the housing 131 (frame 2) by bearings 1324 and 1325. The bearings 1324 and 1325 are formed of, for example, ball bearings.

[0183] The planetary gear mechanism 150 is a mechanism that reduces the speed of the rotational force of the motor 140 and transmits it to the first sprocket 171 via the first output body 162. In this embodiment, the planetary gear mechanism 150 has a motor shaft 143 as a sun gear 1501, an internal gear 1502 that is arranged concentrically with the sun gear 1501, planetary gears 1503 that mesh with the sun gear 1501 and the internal gear 1502, a planetary gear shaft 1504, and a planetary carrier 1505 as an output shaft.

[0184] The internal gear 1502 has an annular shape, and teeth 1502A are formed over the entire inner peripheral surface. The internal gear 1502 is fitted into a protrusion 13111 of the housing 131, and is fixed to the housing 131 so as not to be rotatable.

[0185] The planetary gear 1503 is a stepped planetary gear including two gears with different outer diameters. The planetary gear 1503 has teeth 1503A formed around the entire circumference. A small diameter portion of the planetary gear 1503 meshes with the internal gear 1502, and a large diameter portion of the planetary gear 1503 meshes with the sun gear 1501. By using the stepped planetary gear 1503, it becomes easy to increase the reduction ratio of the planetary gear mechanism 150. Note that the planetary gear 1503 does not have to be a stepped planetary gear, as in the first embodiment.

[0186] The planetary gear shafts 1504 pass through the centers of the planetary gears 1503 and rotatably support the planetary gears 1503. The planetary carrier 1505 supports the planetary gears 1503 so that they can revolve freely. The rotation axis of the planetary carrier 1505 is positioned coaxially with the rotation axis of the sun gear 1501.

[0187] 12, rotor 142, tooth portion 143A of motor shaft 143, tooth portion 1502A of internal gear 1502, and tooth portion 1503A of planetary gear 1503 are arranged in overlapping positions in the axial direction of crankshaft 130. This allows drive unit 120 to be made smaller in size in the axial direction of crankshaft 130.

[0188] Furthermore, at least a portion of the teeth 143A of the motor shaft 143, the teeth 1502A of the internal gear 1502, and the teeth 1503A of the planetary gear 1503 are arranged radially inside the opening 144 of the rotor 142. This allows the drive unit 120 to be further miniaturized.

[0189] The shape, size, material, etc. of the gears of the planetary gear mechanism 150 may be appropriately the same as those of the planetary gear mechanism 51 of the first embodiment.

[0190] The rotational force of the motor 140 output from the planetary gear mechanism 150 is transmitted to the first output body 162 via the one-way clutch 153. When a rotational force in the forward direction is applied to the planetary carrier 1505, the one-way clutch 153 transmits this rotational force to the first output body 162. When a rotational force in the direction opposite to the forward direction is applied to the planetary carrier 1505, the one-way clutch 153 does not transmit this rotational force to the first output body 162.

[0191] The manual power transmission body 161 is a cylindrical member extending along the axial direction of the crankshaft 130, and is disposed on the outer periphery of the crankshaft 130 inside the housing 131. The manual power transmission body 161 rotates integrally with the crankshaft 130. In this embodiment, the manual power transmission body 161 is divided into a first manual power transmission body 1611 and a second manual power transmission body 1612. Note that the manual power transmission body 161 may be formed from a single member.

[0192] The first power transmission body 1611 is connected to the crankshaft 130. The inner peripheral surface of the first power transmission body 1611 is formed with splines or serrations that fit with the crankshaft 130. Note that a portion where the first power transmission body 1611 and the crankshaft 130 fit together may be provided with missing teeth. This allows for positioning in the assembly direction, facilitating assembly. The first power transmission body 1611 and the crankshaft 130 may also be fitted together by press-fitting or screws.

[0193] The second manual power transmission body 1612 is disposed to the right of the first manual power transmission body 1611 in the axial direction of the crankshaft 130. The second manual power transmission body 1612 is connected to the first manual power transmission body 1611 and transmits rotational force to the second output body 163.

[0194] In this embodiment, the outer peripheral surface of the right end of the first manual force transmission body 1611 is formed with splines or serrations that fit with the inner peripheral surface of the left end of the second manual force transmission body 1612. This connects the first manual force transmission body 1611 and the second manual force transmission body 1612.

[0195] The first output body 162 is a shaft member that extends along the axial direction of the crankshaft 130 and to which the rotational force of the motor 140 is transmitted. The rotational axis of the first output body 162 is positioned coaxially with the rotational axis of the motor shaft 143 (sun gear 1501). The rotational force of the motor 140, which is output from the planetary gear mechanism 150, is transmitted to the first output body 162 via the one-way clutch 153.

[0196] In the axial direction of the crankshaft 130, the length of the first output body 162 is shorter than the length of the crankshaft 130, and is, for example, 10% to 50% of the axial length of the crankshaft 130. In addition, the right end of the first output body 162 passes through a through-hole 1316 provided in the housing 131 and protrudes to the outside of the housing 131. The first output body 162 is rotatably supported with respect to the housing 131 by a bearing 1326.

[0197] A spline or serration that fits with the first sprocket 171 is formed on the portion of the first output body 162 that protrudes outside the housing 131. This allows the first sprocket 171 to rotate integrally with the first output body 162.

[0198] The second output body 163 is a cylindrical member extending along the axial direction of the crankshaft 130, and is disposed on the outer periphery of the crankshaft 130. The rotation axis of the second output body 163 is positioned coaxially with the rotation axis of the crankshaft 130.

[0199] The second output body 163 has splines or serrations formed on the inner peripheral surface at the left end thereof that fit with the outer peripheral portion of the second manual power transmission body 1612. This allows the second output body 163 to rotate integrally with the second manual power transmission body 1612. In other words, the rotational force due to the manual driving force output from the manual power transmission body 161 is transmitted to the second output body 163.

[0200] In the axial direction of the crankshaft 130, the length of the second output body 163 is shorter than the length of the crankshaft 130, and is, for example, 10% to 50% of the axial length of the crankshaft 130. In addition, the right end of the second output body 163 passes through a through-hole 1314 provided in the housing 131 and protrudes to the outside of the housing 131. The second output body 163 is rotatably supported with respect to the housing 131 by a bearing 1324.

[0201] The portion of the second output body 163 that protrudes outside the housing 131 is formed with splines or serrations that mate with the second sprocket 172. This allows the second sprocket 172 to rotate integrally with the second output body 163.

[0202] First sprocket 171 is disposed rearward of second sprocket 172. A chain (not shown) is hung between first sprocket 171 and second sprocket 172. The distance between the center of first sprocket 171 and the center of second sprocket 172 is, for example, 150 mm or less, and may be 135 mm or less.

[0203] The second sprocket 172 has a larger outer diameter than the first sprocket 171. The second sprocket 172 also has more teeth than the first sprocket 171.

[0204] [Twelfth embodiment] Next, a twelfth embodiment of a drive unit according to the present disclosure will be described with reference to Figures 22 and 23. Figure 22 is a cross-sectional view of a drive unit 220 according to the twelfth embodiment, and Figure 23 is an enlarged view of the vicinity of the motor 240 in Figure 22. Below, the same reference numerals will be used for components common to the first embodiment, and redundant explanations will be omitted, and differences from the first embodiment will mainly be described.

[0205] 22, the drive unit 220 has a motor 240 that applies a rotational force to assist the pedal force of the pedal 7, a housing 231 that forms part of the outer shell of the drive unit 220, and a crankshaft 230 that is rotatably attached to the housing 231. As will be described in detail later, the rotational shaft of the motor 240 and the rotational shaft of the crankshaft 230 are arranged coaxially.

[0206] The drive unit 220 further includes a pair of hollow crank arms 6, a human power transmission body 261 that is attached to rotate integrally with the crankshaft 230 and rotates by human driving force, an output body 262 that outputs the rotational force of the motor 240, a sprocket 270 that outputs the rotational force of the output body 262, and a power transmission mechanism 250 that reduces the rotational force of the motor 240 and transmits it to the sprocket 270 via the output body 262. As will be described in detail later, the power transmission mechanism 250 is made up of a two-stage reduction mechanism and includes a first planetary gear mechanism (first power transmission mechanism) 251 that is a first-stage reduction mechanism and a second planetary gear mechanism (second power transmission mechanism) 252 that is a second-stage reduction mechanism.

[0207] The crankshaft 230 is a hollow cylindrical member with both ends open. At least a part of the power transmission mechanism 250 is disposed inside the crankshaft 230. This allows the drive unit 220 to be made smaller. The crankshaft 230 is also provided with a through-hole 2301 through which a planetary gear 2523 (described later) passes. The crankshaft 230 is rotatably supported relative to the housing 231 (frame 2) by bearings 2320 and 2321. The bearings 2320 and 2321 are formed of, for example, ball bearings.

[0208] Both ends of the crankshaft 230 protrude outward from the housing 231. The right crank arm 6A is connected to the right end of the crankshaft 230. The right crank arm 6A forms the majority of the right crank arm 6A and includes a base 6A1 having an opening on the left side, and a lid 6A2 that closes the opening. The base 6A1 and the lid 6A2 are joined by a fastening member 6A3 such as a bolt. By joining the base 6A1 and the lid 6A2, a hollow right crank arm 6A is formed.

[0209] The internal space of the crankshaft 230 and the internal space of the right crank arm 6A are connected. The left end of the crankshaft 230 passes through the left crank arm 6B, and an electricity storage device 10 is attached to the left end of the crankshaft 230. As will be described in detail later, the electricity storage device 10 is configured to be detachable from the left end of the crankshaft 230.

[0210] The crankshaft 230 has an inner peripheral surface on the right end side formed with splines or serrations that mate with an internal gear 2512 that constitutes a first planetary gear mechanism 251, which will be described later.

[0211] The housing 231 is a cylindrical member that extends along the axial direction of the crankshaft 230 and covers the central portion of the crankshaft 230. The housing 231 is fixed to the inside of a bottom bracket (not shown), for example. The human power transmission body 261 and a part of the output body 262 are housed inside the housing.

[0212] The inner peripheral surface of the right end of the housing 231 is formed with splines or serrations that mate with an internal gear 2522 that constitutes the second planetary gear mechanism 252, which will be described later.

[0213] 23, the motor 240 includes a stator 241, a rotor 242, and a motor shaft 243 that rotates integrally with the rotor 242. In this embodiment, the motor 240 is an inner rotor type motor. However, the motor 240 may also be an outer rotor type or an axial gap type motor.

[0214] The motor 240 is housed inside the crank arm 6 (right crank arm 6A) and inside the crankshaft 230. Specifically, the stator 241 and the rotor 242 are housed inside the right crank arm 6A, and the motor shaft 243 is housed inside the crankshaft 230. By housing the motor 240 inside the crank arm 6 and inside the crankshaft 230, the drive unit 220 can be made smaller.

[0215] The rotor 242 has an annular shape with a circular opening 244 at its rotation center, and is disposed inside the stator 241. Disposed radially inside the opening 244 are a sun gear 2511, an internal gear 2512, a planetary gear 2513, and a part of a planetary gear shaft 2514, which are gears that constitute the first planetary gear mechanism 251.

[0216] The rotor 242 and the motor shaft 243 are fixed together by serrations. The rotor 242 and the motor shaft 243 may also be fixed together by press fitting, shrink fitting, cold fitting, or the like. When fixing the rotor 242 and the motor shaft 243 together, an elastic member such as a rubber member or urethane may be provided between the rotor 242 and the motor shaft 243.

[0217] The motor shaft 243 is a cylindrical shaft member that extends in the left-right direction and rotates integrally with the rotor 242. The motor shaft 243 is disposed so that its rotation axis is aligned with the axial direction of the crankshaft 230. The motor shaft 243 is rotatably supported with respect to the crankshaft 230 and the right crank arm 6A by a bearing 2322 provided in the right crank arm 6A.

[0218] The motor shaft 243 is disposed so that its central axis of rotation passes through the center of the internal gear 2512 that constitutes the first planetary gear mechanism 251, and passes through the internal gear 2512. In addition, a toothed portion 243A that meshes with a toothed portion 2513A of the planetary gear 2513 that constitutes the first planetary gear mechanism 251 is provided on the surface of the motor shaft 243. In other words, the motor shaft 243 functions as a sun gear 2511 of the first planetary gear mechanism 251, and constitutes a gear of the first planetary gear mechanism 251.

[0219] The size, shape, etc. of the motor 140 can be appropriately adopted from the size, shape, etc. of the motor 40 of the first embodiment.

[0220] The power transmission mechanism 250 is a mechanism that reduces the speed of the rotational force of the motor 240 and transmits it to the sprocket 270 via the output body 262. In this embodiment, the power transmission mechanism 250 is composed of a two-stage reduction mechanism, and includes a first planetary gear mechanism 251 that is the first-stage reduction mechanism and a second planetary gear mechanism 252 that is the second-stage reduction mechanism. Note that the power transmission mechanism 250 may also be composed of a single-stage reduction mechanism.

[0221] As shown in FIG. 23, the first planetary gear mechanism 251 has a motor shaft 243 as a sun gear 2511, an internal gear 2512 arranged concentrically with the sun gear 2511, planetary gears 2513 meshing with the sun gear 2511 and the internal gear 2512, respectively, a planetary gear shaft 2514, and a planetary carrier 2515 as an output shaft.

[0222] The internal gear 2512 has an annular shape, and teeth 2512A are formed over the entire area of ​​the inner peripheral surface. The internal gear 2512 is fitted with the inner peripheral surface of the crankshaft 230, and is thereby fixed to the crankshaft 230 so as not to be rotatable.

[0223] Teeth 2513A are formed around the entire circumference of the planetary gear 2513. Planetary gear shafts 2514 pass through the centers of the planetary gears 2513 and rotatably support the planetary gears 2513. A planetary carrier 2515 supports the planetary gears 2513 so that they can revolve freely. The rotation axis of the planetary carrier 2515 is coaxial with the rotation axis of the sun gear 2511.

[0224] 23, rotor 242, tooth portion 243A of motor shaft 243, tooth portion 2512A of internal gear 2512, and tooth portion 2513A of planetary gear 2513 are arranged at overlapping positions in the axial direction of crankshaft 230. This allows drive unit 220 to be made smaller in size in the axial direction of crankshaft 230.

[0225] Furthermore, at least a portion of teeth 243A of motor shaft 243, teeth 2512A of internal gear 2512, and teeth 2513A of planetary gear 2513 are arranged radially inside opening 244 of rotor 242. This allows drive unit 220 to be further miniaturized.

[0226] The rotational force of the motor 240 output from the first planetary gear mechanism 251 is transmitted to the second planetary gear mechanism 252 via the one-way clutch 253. When a rotational force in the forward direction is applied to the planetary carrier 2515, the one-way clutch 253 transmits this rotational force to the sun gear 2521, which is the input shaft of the second planetary gear mechanism 252. When a rotational force in the direction opposite to the forward direction is applied to the planetary carrier 2515, the one-way clutch 253 does not transmit this rotational force to the sun gear 2521.

[0227] As shown in Figure 23, the second planetary gear mechanism 252 has a sun gear 2521 which is an input shaft, an internal gear 2522 which is arranged concentrically with the sun gear 2521, a planetary gear 2523 which meshes with the sun gear 2521 and the internal gear 2522, respectively, and a planetary gear shaft 2524.

[0228] The sun gear 2521 has a rotation axis that is coaxial with the rotation axis of the crankshaft 230. As described above, the rotational force of the motor 240 output from the first planetary gear mechanism 251 is transmitted to the sun gear 2521 via the one-way clutch 253. The sun gear 2521 is rotatably supported with respect to the crankshaft 230 by a bearing 2323 provided on the left end side.

[0229] The internal gear 2522 has an annular shape, and teeth 2522A are formed over the entire area of ​​the inner peripheral surface. The internal gear 2522 is fitted into the inner peripheral surface of the housing 231, and is fixed to the housing 231 so as not to be rotatable.

[0230] The planetary gear 2523 is a stepped planetary gear including two gears with different outer diameters. The planetary gear 2523 has teeth 2523A formed around the entire circumference. A small diameter portion of the planetary gear 2523 meshes with the internal gear 2522, and a large diameter portion of the planetary gear 2523 meshes with the sun gear 2521. Use of the stepped planetary gear 2523 makes it easy to increase the reduction ratio of the second planetary gear mechanism 252. Note that the planetary gear 2523 does not have to be a stepped planetary gear, as in the first embodiment.

[0231] The planetary gear shaft 2524 passes through the center of each planetary gear 2523 and rotatably holds the planetary gears 2523. The planetary gear shaft 2524 is inserted into and fitted into a through hole formed in the output body 262. This allows the rotational force of the motor 240 output from the second planetary gear mechanism 252 to be transmitted to the output body 262.

[0232] The shapes, sizes, materials, etc. of the gears of the first planetary gear mechanism 251 and the second planetary gear mechanism 252 can be appropriately adapted from the shapes, sizes, materials, etc. of the gears of the planetary gear mechanism 51 of the first embodiment.

[0233] 22, the power transmission body 261 is a cylindrical member extending along the axial direction of the crankshaft 230, and is disposed on the outer periphery of the crankshaft 230 inside the housing 231. The power transmission body 261 rotates integrally with the crankshaft 230. In this embodiment, the power transmission body 261 is formed of one member, but may be formed of multiple members, as in the first embodiment.

[0234] The power transmission body 261 is connected to the crankshaft 230. A spline or serration that engages with the crankshaft 230 is formed on the inner peripheral surface of the left end of the power transmission body 261. The power transmission body 261 and the crankshaft 230 may be engaged by press fitting or threading. In the axial direction of the crankshaft 230, the length of the power transmission body 261 is shorter than the length of the crankshaft 230, for example, 10% to 50% of the axial length of the crankshaft 230. The drive unit 220 does not necessarily have to include the power transmission body 261. In this case, the output body 262 and the crankshaft 230 are engaged by a spline or the like, and the rotational force of the crankshaft 230 is transmitted to the output body 262. In addition, if the power transmission body 261 is not provided, the strain of the crankshaft 230 may be detected by a strain sensor or the like attached to the outer peripheral surface of the crankshaft 230 to detect the power input torque. Furthermore, the manual input torque may be detected by using a strain sensor to detect the load on the outer ring side of bearing 2321. This eliminates the need for manual power transmission body 261, making it easier to make drive unit 220 smaller and lighter.

[0235] The right end of the manual power transmission body 261 has teeth on its outer periphery that mesh with teeth on the inner periphery of the output body 262. This allows the rotational force generated by the manual driving force to be transmitted to the output body 262 via the manual power transmission body 261. A one-way clutch may be provided between the manual power transmission body 261 and the output body 262.

[0236] The output body 262 is a cylindrical member extending along the axial direction of the crankshaft 230, and is disposed on the outer periphery of the crankshaft 230. The rotation axis of the output body 262 is positioned coaxially with the rotation axis of the crankshaft 230.

[0237] In the axial direction of crankshaft 230, the length of output body 262 is shorter than the length of crankshaft 230, and is, for example, 10% to 50% of the axial length of crankshaft 230. Output body 262 is rotatably supported relative to housing 231 by bearing 2320.

[0238] The right end of the output body 262 passes through a through-hole 2311 provided in the housing 231 and protrudes outside the housing 231. A spline or serration that fits with the sprocket 270 is formed on the portion of the output body 262 that protrudes outside the housing 231. This allows the sprocket 270 to rotate integrally with the output body 262.

[0239] In this embodiment, the human power transmission body 261 and the output body 262 are provided separately, but they may also be configured as an integrated unit. For example, the human power transmission body 261 may not be provided, and only the output body 262 may be provided. In this case, the rotational force of the crankshaft 230 caused by the human driving force is transmitted to the output body 262, thereby moving the power-assisted bicycle 1 forward.

[0240] A one-way clutch may be disposed between the output body 262 and the sprocket 270. When a rotational force in the forward direction is applied to the output body 262, the one-way clutch transmits the rotational force to the sprocket 270. When a rotational force in the direction opposite to the forward direction is applied to the output body 262, the one-way clutch does not transmit the rotational force to the sprocket 270.

[0241] 22, the drive unit 220 includes a torque detector 280 that detects the torque of the manual driving force, and a control board 281 on which a control device (not shown) is mounted to control the output of the motor 240 in accordance with the detected torque and realize an appropriate electric assist function. The drive unit 220 also includes a rotation detector 282 that detects the rotation of the crankshaft 230.

[0242] The torque detection unit 280 is provided on the outer periphery of the power transmitting body 261 and detects strain applied to the power transmitting body 261. For example, a strain sensor that detects physical strain can be used as the torque detection unit 280. Alternatively, for example, a paint that emits light in response to a mechanical stimulus can be applied to the outer periphery of the power transmitting body 261, and the light can be detected by an optical sensor.

[0243] When torque is detected using a strain sensor, the drive unit 220 is provided with two torque detectors 280, one on each side, at positions facing each other in the circumferential direction on the outer periphery of the power transmitting body 261. Only one torque detector 280 may be provided on the outer periphery of the power transmitting body 261, or three or more torque detectors 280 may be provided. Furthermore, the installation location of the torque detector 280 is not limited to the outer periphery of the power transmitting body 261, and it may be disposed on the outer periphery of the crankshaft 230, for example.

[0244] The control device is disposed on a control board 281, and controls the rotation of the motor 240 based on the torque detected by the torque detection unit 280. The control device also controls the rotation of the motor 240 based on the detection information of the rotation detection unit 282. A conventionally known configuration can be adopted as the configuration of the control device. Communication between the torque detection unit 280 and the control device may be performed using a signal line or a wireless signal. Note that the control board 281 on which the control device is disposed may also be disposed near the motor 240, as shown in FIG. 22 . The control board 281 disposed near the motor 240 may be provided with, for example, a rotor rotation detection unit for detecting the rotation of the rotor 242.

[0245] In this embodiment, the control board 281 is housed inside the right crank arm 6A. That is, the control board 281 rotates integrally with the crankshaft 230. By housing the control board 281 inside the right crank arm 6A, it becomes easier to make the drive unit 220 more compact.

[0246] The rotation detection unit 282 detects the number of rotations of the crankshaft 230. The rotation detection unit 282 is, for example, an inertial sensor such as an acceleration sensor or a gyro sensor. However, the configuration of the rotation detection unit 282 is not limited to this.

[0247] In this embodiment, at least a portion of the rotation detection unit 282 is disposed on the control board 281. That is, at least a portion of the rotation detection unit 282 rotates integrally with the crankshaft 230. This facilitates downsizing of the drive unit 220. Note that at least a portion of the rotation detection unit 282 may be disposed on the crankshaft 230 or the human power transmitting body 261.

[0248] Communication between the rotation detector 282 and the control device may be via a signal line, but it is preferable to use a wireless signal. This saves space for accommodating the signal line connecting the rotation detector 282 and the control device, making it easier to miniaturize the drive unit 220.

[0249] 22, the electricity storage device 10 is attached to the left end of the crankshaft 230. In other words, the electricity storage device 10 rotates integrally with the crankshaft 230.

[0250] The electricity storage device 10 includes a housing 10A that houses a storage battery 10C and is disposed outside the crankshaft 230, and a connector 10B that is connected to the housing 10A. The housing 10A and the connector 10B are joined with a fastening member 10D such as a bolt. The housing 10A has a recess 10E into which the crankshaft 230 fits. A control board 10H that controls the electricity storage device 10 is provided inside the housing 10A.

[0251] The power storage device 10 is configured to be detachable from the crankshaft 230. Specifically, a key mechanism 10F is provided on the outer side of the housing 10A in the radial direction of the rotation axis of the crankshaft 230. When the key mechanism 10F is unlocked, the convex portion 10G retreats from the engagement portion, loosening the fastening of the concave portion 10E, allowing the power storage device 10 to be removed from the crankshaft 230. Furthermore, by locking the key mechanism 10F with the crankshaft 230 fitted in the concave portion 10E, the convex portion 10G engages with the engagement portion, fastening the crankshaft 230 with the concave portion 10E, and fixing the power storage device 10 to the crankshaft 230. The configuration of the key mechanism 10F is not particularly limited as long as it is configured to allow the power storage device 10 to be detachable from the crankshaft 230. For example, the key mechanism 10F may be disposed axially of the crankshaft 230.

[0252] Connector 10B is disposed inside crankshaft 230 and configured to be insertable into the left end of an internal connector 284 inside crankshaft 230. The outer diameter of connector 10B is configured to be smaller than the inner diameter of crankshaft 230. A cable 283 that supplies power to components that configure drive unit 220, such as motor 240, is connected to the right end of internal connector 284. In the example shown in FIG. 22 , cable 283 passes through crankshaft 230 and is connected to control board 81 that is disposed inside right crank arm 6A.

[0253] The method of supplying power to the components that make up the drive unit 220 is not limited to this. For example, the power storage device 10 may be attached to the frame 2, and power may be supplied to the drive unit 220 using a slip ring. For example, the drive unit 220 includes a power receiving unit that rotates integrally with the crankshaft 230, and a power supply unit that is fixed to the frame 2 and has a brush that supplies power to the power receiving unit. A slip ring is provided in the power receiving unit, and the tip of the brush comes into contact with and slides as the slip ring rotates, and power is supplied from the brush to the slip ring. The method of supplying power using a slip ring is not limited to the above-mentioned embodiment.

[0254] The above-described embodiments may be modified as needed within the scope of the present disclosure. For example, while the above-described embodiments describe an electrically assisted bicycle 1 in which crank arms 6 are provided on both ends of the crankshaft 30, 130, 230, the present invention may also be applied to an electrically assisted vehicle in which crank arms 6 are not provided on both ends of the crankshaft 30, 130, 230. In other words, the present invention may also be applied to an electrically assisted vehicle that moves forward not by human drive force but by the rotational force of a motor. [Explanation of symbols]

[0255] 1 Electrically assisted bicycle, 2 Frame, 2A Head pipe, 2B Front fork, 2C Top pipe, 2D Down pipe, 2E Seat pipe, 2F Seat stay, 2G Chain stay, 3A Front wheel, 3B Rear wheel, 4 Handlebar, 5 Saddle, 6 Crank arm, 6A Right crank arm, 6A1 Base, 6A2 Lid, 6A3 Fastening member, 6B Left crank arm, 7 Pedal, 8 Chain, 10 Power storage device, 10A Container, 10B Connector, 10C Storage battery, 10D Fastening member, 10E Recess, 10F Key mechanism, 10G Protrusion, 10H Control board, 11 Rear wheel sprocket, 20, 20A, 20B, 20C, 20D, 20E, 20F, 20G, 120, 220 Drive unit, 30, 130, 230 Crankshaft, 31, 31E, 31F, 131, 231 Housing, 33 Heat dissipation member, 34, 134, 341, 342 Fastening member, 35 Heat dissipation member, 36 Protruding member, 40, 40A, 40D, 140, 240 Motor, 41, 41A, 41D, 141, 241 Stator, 42, 42A, 42D, 142, 242 Rotor, 43, 43D, 143, 243 Motor shaft, 43A, 143A, 243A, 512A, 513A, 541A, 542A, 1502A, 1503A, 2512A, 2513A, 2522A, 2523A Teeth, 44, 144, 244 Opening, 50, 50B, 50C, 50F, 50G, 250 Power transmission mechanism, 51, 51B, 51F, 150, 251 Planetary gear mechanism, 52 Second reduction mechanism, 53, 53G, 63, 153, 253 One-way clutch, 61, 161, 162 Power transmission body, 62, 262 Output body, 70, 270 Sprocket, 80, 280 Torque detection unit, 81, 281 Control board, 82, 282 Rotation detection unit, 83, 283 Cable, 84 Connector, 85 Rotor rotation detection unit, 86, 86J Magnet, 162 First output body, 163 Second output body, 171 First sprocket, 172 Second sprocket, 251 First planetary gear mechanism, 252 Second planetary gear mechanism, 284 Internal connector, 311, 311E, 311F, 1311 First division body, 312, 312E, 312F, 1312 Second division body, 313E, 313F Third division body, 314, 315, 1314, 1315, 1316, 2301, 2311 Through hole, 320, 321,322, 323, 324, 325, 326, 327, 1329, 1321, 1322, 1324, 1325, 1326, 2320, 2321, 2322, 2323 Bearings, 511, 511F, 1501, 2511, 2521 Sun gears, 512, 512F, 1502, 2512, 2522 Internal gears, 513, 513F, 1503, 2513, 2523 Planet gears, 514, 514F, 1504, 2514, 2524 Planet gear shafts, 515, 515B, 515C, 515F, 1505, 2515 Planet carriers, 516 Output members, 521, 541 First transmission gear, 522, 543 Second transmission gear, 542 Gear shaft, 611, 1611 First human power transmission body, 612, 1612 Second human power transmission body, 841 First part, 842 Second part, 1312A Groove, 3111, 3131, 13111 Protrusion, 3112, 3132 Recess, 5121 Annular part, 5122 Connecting part, 5123 Cylindrical part, 5151 Hollow part, 5161 Convex part, 5162 Small diameter part

Claims

1. A drive unit for use in an electric vehicle, a motor including a rotor having an opening at its center of rotation; a housing that accommodates the motor; a crankshaft rotatably mounted relative to the housing; a sprocket that outputs the rotational force of the motor; a power transmission mechanism that reduces or increases the rotational force of the motor and transmits the rotational force to the sprocket; Equipped with the power transmission mechanism includes at least one gear having teeth on a surface thereof, the rotor and the tooth portion are arranged at positions where they overlap in the axial direction of the crankshaft, At least a portion of the gear is disposed inside the opening.

2. A drive unit for use in an electric vehicle, a motor including a rotor having an opening at its center of rotation; a housing that accommodates the motor; a crankshaft rotatably attached to the housing and rotatable by manual drive; a first sprocket that outputs the rotational force of the motor; a second sprocket for outputting the rotational force of the manual driving force; a power transmission mechanism that reduces or increases the rotational force of the motor and transmits the rotational force to the first sprocket; Equipped with the power transmission mechanism includes at least one gear having teeth on a surface thereof, the rotor and the tooth portion are arranged at positions where they overlap in the axial direction of the crankshaft, At least a portion of the gear is disposed inside the opening.

3. The crankshaft is rotatable by manual driving force, a torque detection unit that detects a manual driving force applied to the crankshaft; a control device that controls the rotation of the motor based on the detection information of the torque detection unit; The drive unit according to claim 1 or 2, further comprising:

4. 3. The drive unit according to claim 1, wherein the power transmission mechanism includes a planetary gear mechanism having a planetary gear, a planetary gear shaft, and a planetary carrier.

5. The drive unit according to claim 4 , wherein the gears of the planetary gear mechanism include helical gears.

6. 5. The drive unit according to claim 4, wherein the planetary gear mechanism further includes an internal gear, the internal gear being fixed non-rotatably relative to the housing.

7. 5. The drive unit according to claim 4, wherein the planetary gear mechanism further includes a sun gear, the sun gear being fixed non-rotatably relative to the housing.

8. The drive unit according to claim 4 , wherein the planet carrier is fixed non-rotatably relative to the housing.

9. the power transmission mechanism is a mechanism that reduces or increases the rotational force of the motor in multiple stages, a first power transmission mechanism; a second power transmission mechanism that is located downstream of the first power transmission mechanism in a transmission path and to which the rotational force of the first power transmission mechanism is transmitted; Including, a first bearing that rotatably supports a gear that constitutes the second power transmission mechanism with respect to the housing; a one-way clutch provided between the first power transmission mechanism and the second power transmission mechanism; Furthermore, 3. The drive unit according to claim 1, wherein the first bearing and the one-way clutch are arranged at positions where they overlap in the axial direction of the crankshaft.

10. the power transmission mechanism reduces or increases the rotational force of the motor in multiple stages; The power transmission mechanism includes: a first power transmission mechanism having a sun gear, planet gears, a planet carrier, and an internal gear; a second power transmission mechanism that is located downstream of the first power transmission mechanism in a transmission path and to which the rotational force of the first power transmission mechanism is transmitted, a second bearing is provided at one end of the sun gear within the housing to support the sun gear rotatably relative to the housing; the second bearing and the second power transmission mechanism are disposed at positions where they overlap in the axial direction of the crankshaft, 3. The drive unit according to claim 1, wherein the rotation axis of the rotor and the rotation axis of the crankshaft are arranged on different axes.

11. the power transmission mechanism includes a cylindrical output member that meshes with an output shaft of the planetary gear mechanism, the output member has a small diameter portion formed to have a smaller diameter than other portions, The drive unit according to claim 5 , further comprising a third bearing disposed radially outward of the small diameter portion, the third bearing supporting the output member rotatably relative to the housing.

12. 3. The drive unit according to claim 1, wherein the power transmission mechanism includes a parallel shaft gear mechanism having a gear that meshes with a motor shaft that is an output shaft of the motor and whose rotation axis is arranged parallel to the rotation axis of the motor shaft.

13. a control board on which a control device for controlling the rotation of the motor is disposed; 3. The drive unit according to claim 1, wherein the control board is joined to the motor.

14. the motor includes a stator; 3. The drive unit according to claim 1, wherein the outer diameter of the stator is 100 mm or less.

15. the motor includes a stator; 3. The drive unit according to claim 1, wherein the outer diameter of the stator is 90 mm or less.

16. 3. The drive unit according to claim 1, wherein the rotor has an inner diameter of 30 mm or more.

17. 3. The drive unit according to claim 1, wherein the rotor has an inner diameter of 40 mm or more.

18. Further, a rotation detection unit that detects the rotation of the crankshaft is provided, The drive unit according to claim 3 , wherein at least a part of the rotation detector is disposed on a substrate on which the control device is disposed.

19. The drive unit according to claim 18 , wherein the torque sensing portion is disposed on the substrate.

20. A cable extending from outside the drive unit is connected to the board on which the control device is disposed via a connector, 4. The drive unit of claim 3, wherein the connector includes a first portion extending along a direction approximately normal to the surface of the substrate, and a second portion extending along a direction inclined relative to the direction approximately normal to the surface of the substrate.

21. The torque detector rotates integrally with the crankshaft, The drive unit according to claim 3 , wherein the torque detector and the control device communicate with each other by radio signals.

22. the housing is fixed to a frame of the electric vehicle; 3. The drive unit according to claim 1, wherein the housing has a heat dissipation portion that transfers heat to the frame.

23. The interior of the housing is divided into at least two spaces, 3. The drive unit according to claim 1, wherein a lubricant is stored in the space in which the power transmission mechanism is disposed.

24. A drive unit for use in an electric vehicle, a motor including a rotor having an opening at its center of rotation; Housing and a crankshaft rotatably mounted relative to the housing; a sprocket that outputs the rotational force of the motor; a power transmission mechanism that reduces or increases the rotational force of the motor and transmits the rotational force to the sprocket; Equipped with the power transmission mechanism includes at least one gear having teeth on a surface thereof, the rotor and the tooth portion are arranged at positions where they overlap in the axial direction of the crankshaft, a drive unit in which the rotation axis of the rotor and the rotation axis of the crankshaft are arranged coaxially.

25. The crankshaft has a hollow structure, 25. The drive unit of claim 24, wherein at least a portion of the power transmission mechanism is housed within the crankshaft.

26. further comprising a power storage device that supplies power to the motor; 25. The drive unit according to claim 24, wherein the power storage device rotates integrally with the crankshaft.

27. a one-way clutch disposed between the crankshaft and the power transmission mechanism, 25. The drive unit of claim 24, wherein the one-way clutch is radially loaded.

28. 28. The drive unit according to claim 27, wherein the one-way clutch is disposed closer to the sprocket than an axial center portion of the crankshaft in the axial direction of the crankshaft.

29. A drive unit for use in an electric vehicle, A motor; a housing that accommodates the motor; a crankshaft rotatably mounted relative to the housing; a sprocket that outputs the rotational force of the motor; a power transmission mechanism that reduces or increases the rotational force of the motor and transmits the rotational force to the sprocket; a rotation detection unit that detects rotation of the crankshaft or a member that rotates integrally with the crankshaft; Equipped with The rotation detection unit is a drive unit that rotates integrally with the crankshaft.

30. a control device that controls the rotation of the motor based on the detection information of the rotation detection unit; 30. The drive unit according to claim 29, wherein the rotation detector and the control device communicate with each other by wireless signals.

31. The drive unit according to claim 30, wherein the rotation detector and the control device are arranged on the same substrate.

32. A drive unit for use in an electric vehicle, A motor; a housing that accommodates the motor; a crankshaft rotatably mounted relative to the housing; a sprocket that outputs the rotational force of the motor; a power transmission mechanism that reduces or increases the rotational force of the motor and transmits the rotational force to the sprocket; Equipped with The motor a motor shaft serving as an output shaft; a stator fixed to the housing; a rotor fixed to the motor shaft and having a magnet; Including, the rotor is disposed to face the stator in a direction along the rotation axis of the motor shaft, the power transmission mechanism includes at least one gear having teeth on a surface thereof, The drive unit is arranged such that the stator and the tooth portion overlap in the axial direction of the crankshaft.

33. 33. The drive unit according to claim 32, wherein the rotor is disposed on only one side of the stator in a direction along the rotation axis of the motor shaft.

34. The motor shaft further includes a plurality of bearings that rotatably support the motor shaft relative to the housing, 33. The drive unit according to claim 32, wherein the plurality of bearings are spaced apart in a direction along the rotation axis of the motor shaft.

35. 33. The drive unit according to claim 1, further comprising a bearing for rotatably supporting the crankshaft, and detecting a load acting on the bearing.

36. An electric vehicle comprising a drive unit according to any one of claims 1, 2, 24, 29 and 32.

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