Assist drive unit

Abstract

To provide an assist drive unit in which an assist motor is located coaxially with a pedal crank shaft and related components are compactly arranged.SOLUTION: An assist drive unit comprises: a first one-way clutch 26 which transmits a torque when a pedal crank shaft 3 normally rotates with respect to a unit output member 19, and does not transmit a load when the pedal crank shaft 3 reversely rotates with respect to the unit output member 19; and a second one-way clutch 28 which transmits an assist torque when an assist output member 47 normally rotates with respect to the unit output member 19. The first one-way clutch 26 and the second one-way clutch 28 are arranged coaxially with the pedal crank shaft 3 and are arranged side by side in an axial direction of the pedal crank shaft 3, and further, are arranged at a position where the clutches overlap with the assist motor 15 when viewed from a radian direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an assist drive unit. [Background technology]

[0002] In a conventional drive unit for an electric-power-assisted bicycle that applies an assist torque from an electric motor in response to the pedaling force of a rider, Patent Document 1, for example, discloses a drive unit 9 that includes an input-side one-way clutch 44 that transmits a human-powered driving force F1 from the pedal crankshaft 15 to the input rotor 23 but does not transmit a force in the opposite direction (auxiliary driving force F2 from the motor 8) from the input rotor 23 to the pedal crankshaft 15, and an output-side one-way clutch 45 that is provided in the rotation transmission path between the input rotor 23 and the rotation output part 17 (between the outer periphery of the cylindrical part 23b of the input rotor 23 and the inner periphery of the rotation output part 17). Gear teeth on the outer periphery of the input rotor 23 are connected to the motor 8, which is a separate shaft from the pedal crankshaft 15. For example, Patent Document 2 discloses a drive unit 20 in which a motor 31, a planetary roller reducer 40, and a one-way clutch 58 are arranged coaxially with a pedal crankshaft 39, and a one-way clutch 55 and a gear shaft 54 ​​are arranged on a separate shaft from the pedal crankshaft 39. The manual driving force is transmitted to the drive sprocket 4 via the one-way clutch 58, which is coaxial with the pedal crankshaft 15, and the motor driving force is transmitted to the sprocket 4 via the one-way clutch 55 and the gear shaft 54, which are on a separate shaft from the pedal crankshaft 15. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-135022 [Patent Document 2] Japanese Patent Application Publication No. 11-79060 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described assist drive unit, if the assist motor is mounted on a separate shaft from the pedal crankshaft, the overall length of the unit increases and the weight tends to increase. On the other hand, if the assist motor is mounted coaxially with the pedal crankshaft, the single-shaft structure requires that the components be arranged compactly.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an assist drive unit in which an assist motor is arranged coaxially with the pedal crankshaft and related components are arranged compactly. [Means for solving the problem]

[0006] As a means for solving the above problem, a first aspect of the present invention is an assist drive unit (10) that applies assist torque to a pedal crankshaft (3) from an assist motor (15) that is arranged coaxially with the pedal crankshaft (3), the assist drive unit (10) including a unit output member (19) that is arranged coaxially with the pedal crankshaft (3) and outputs a drive force to the outside of the unit, and a first one-wheel mechanism that can transmit torque when the pedal crankshaft (3) rotates relative to the unit output member (19) in the vehicle traveling direction, and that spins idly and cannot transmit torque when the pedal crankshaft (3) rotates relative to the unit output member (19) in the direction opposite to the vehicle traveling direction. The vehicle is equipped with a one-way clutch (26), an assist output member (47) arranged coaxially with the unit output member (19) and which outputs the assist torque of the assist motor (15), and a second one-way clutch (28) which enables the assist torque to be transmitted when the assist output member (47) rotates in the vehicle travel direction relative to the unit output member (19). The first one-way clutch (26) and the second one-way clutch (28) are arranged coaxially with the pedal crankshaft (3), are arranged side by side in the axial direction of the pedal crankshaft (3), and are further arranged in a position overlapping with the assist motor (15) when viewed radially. According to this configuration, the first one-way clutch, which allows the pedal crankshaft to rotate in the reverse direction, and the second one-way clutch for transmitting assist torque are arranged coaxially, and both one-way clutches are arranged within the axial width of the assist motor, thereby enabling the related parts to be arranged compactly and the overall unit to be made smaller.

[0007] A second aspect of the present invention is the first aspect described above, further comprising a sensor shaft (18) arranged coaxially with the pedal crankshaft (3) and axially adjacent to the unit output member (19), wherein one axial end of the sensor shaft (18) is supported by the pedal crankshaft (3) so as to be rotatable integrally with the pedal crankshaft (3), and the other axial end is supported by the pedal crankshaft (3) via a needle bearing (27) so as to be rotatable relative to the pedal crankshaft (3), and a first one-way clutch (26) is supported on the outer periphery of the other axial end of the sensor shaft (18). According to this configuration, a sensor shaft is provided with one axial end fixed to the pedal crankshaft and the other axial end supported via a needle bearing, and by supporting a first one-way clutch on the outer periphery of the other axial end of the sensor shaft, the first one-way clutch is supported with high rigidity and torsion between the two axial ends of the sensor shaft is not hindered, allowing for good torque detection based on torsion of the sensor shaft.

[0008] A third aspect of the present invention is the first or second aspect, which is provided with a reducer (40) located on the inner periphery of the assist motor (15) and positioned so as to overlap with the assist motor (15) when viewed radially. According to this configuration, the reducer is disposed on the inner periphery of the assist motor and within the axial width of the assist motor, thereby enabling the related parts to be disposed compactly and the overall unit to be made smaller.

[0009] In a fourth aspect of the present invention, in the third aspect, the assist motor (15) is an inner rotor type, and an internal gear (41) of the reducer (40) is provided on the inner periphery of the rotor (15a) of the assist motor (15). With this configuration, the internal gear of the reducer is provided on the inner periphery of the inner rotor of the assist motor, so that the input shaft for the reducer can be used as well as the rotor shaft to which the magnets of the assist motor are attached. Also, by using a common material such as S45C for the rotor, it can be used as a back yoke for the magnetic path of the electromagnetic part.

[0010] In a fifth aspect of the present invention, in the fourth aspect, the reducer (40) includes a pair of axially adjacent internal planetary gear reducers (40a), and the internal gears (41) of the pair of internal planetary gear reducers (40a) are supported on the inner periphery of the integral rotor (15a) via respective eccentric oscillation bearings (42), and thrust receivers (40b) are attached to both axial sides of the inner periphery of the rotor (15a) to restrict axial movement of the eccentric oscillation bearings (42). With this configuration, when a pair of axially adjacent internal planetary gear reducers operate, a precession force is generated, which applies a thrust force to the output gear. This may cause the eccentric oscillation bearing provided on the input gear (internal gear) to come loose from the input gear. To mitigate this effect, for example, ordinary circlips can be provided on both axial sides of the eccentric oscillation bearing as thrust receivers, thereby suppressing the impact of the thrust force on the output gear. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide an assist drive unit in which an assist motor is arranged coaxially with a pedal crankshaft and related components are arranged compactly. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a left side view of a bicycle according to an embodiment of the present invention. [Figure 2] 3 is a cross-sectional view of the bicycle's assist drive unit taken along the axial direction. FIG. [Figure 3] FIG. 2 is a perspective view of a rotor of an assist motor of the assist drive unit. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, directions such as front, rear, left, and right are the same as directions in the vehicle described below unless otherwise specified. In addition, an arrow FR indicating the front of the vehicle, an arrow LH indicating the left side of the vehicle, and an arrow UP indicating the top of the vehicle are shown in appropriate locations in the drawings used in the following description. The term "middle" used in this embodiment refers not only to the center between both ends of an object, but also to the range inside the both ends of an object. In the following description, it is assumed that the body of the vehicle is in an upright position without tilting left or right.

[0014] FIG. 1 is a left side view of a bicycle 1 according to an embodiment. The bicycle 1 shown in Figure 1 is an electrically assisted bicycle equipped with an assist motor 15 that generates assist power in response to the force applied to pedals 2. Bicycle 1 is equipped with an assist drive unit 10 mounted around pedal crankshaft 3 that runs along the left-right direction, and a battery 5 mounted, for example, along body frame 4. In the figure, reference numerals 6, 7, 8, 9, 2a, 2b, 2c, and C1 indicate the central axis of rotation of pedal crankshaft 3. Hereinafter, the direction along axis C1 will be referred to as the axial direction, the direction perpendicular to axis C1 as the radial direction, and the direction around axis C1 as the circumferential direction.

[0015] FIG. 2 is a cross-sectional view of the assist drive unit 10 of the bicycle 1 taken along the axial direction. 2, the assist drive unit 10 includes an assist motor 15 arranged coaxially with the pedal crankshaft 3, a reducer 40 also arranged coaxially with the pedal crankshaft 3 and transmitting the driving force (torque) of the assist motor 15 to the pedal crankshaft 3, and a unit case 11 that houses the assist motor 15 and the reducer 40 and is supported by the body frame 4. The assist drive unit 10 is a compact, single-axis electric drive unit in which the assist motor 15 and the reducer 40 are arranged coaxially with the pedal crankshaft 3, and is a drive unit that can be suitably used in an electrically assisted bicycle.

[0016] The unit case 11 is divided into left and right case bodies 12, 13 in the vehicle width direction. The left case body 12 is formed in a cylindrical shape with a bottom that opens to the right, and the right case body 13 is formed in a cylindrical shape with a bottom that opens to the left. The right case body 13 is deeper in the vehicle width direction than the left case body 12. An assist motor 15 and a reducer 40 are housed in a closed space formed by the left and right case bodies 12, 13 butting their open portions against each other. In particular, the assist motor 15 and the reducer 40 are housed inside the right case body 13, and control system components such as a control board 36 and a sensor 37 are housed inside the left case body 12. The left and right case bodies 12, 13 are each integrally formed as a cast part made of, for example, an aluminum alloy.

[0017] The left case body 12 has a left side wall 12a facing the left side of the vehicle, and a left outer peripheral wall 12b extending rightward (toward the right case body 13) from the outer periphery of the left side wall 12a. A left bearing portion 22 is provided in the center of the left side wall 12a to support the left side of the pedal crankshaft 3 and a sensor shaft 18 (described later) via a left bearing 22a. The right case body 13 includes a right side wall 13a facing the right side of the vehicle, and a right outer peripheral wall 13b extending leftward (toward the left case body 12) from the outer periphery of the right side wall 13a. A right bearing portion 23 is provided in the center of the right side wall 13a to support the right side of the pedal crankshaft 3 and an output shaft (unit output member) 19 (described later) via a right bearing 23a. The left and right bearings 22a, 23a can be ball bearings of the same configuration, and costs can be reduced by using common parts.

[0018] The assist motor 15 is an inner rotor type motor and includes a cylindrical stator 15b fixed to the inside of the right outer peripheral wall 13b of the right case body 13, and a similarly cylindrical rotor 15a disposed on the inner periphery of the stator 15b. The assist motor 15 in this embodiment is, for example, a DC motor, but the type of motor is not particularly limited. FIG. 3 is a perspective view of the rotor 15a. Referring also to FIG. 3, a plurality of permanent magnets 15a1 are fixed to the outer periphery of the rotor 15a and arranged in the circumferential direction. An input gear 41 of a reducer 40 is supported on the inner periphery of the rotor 15a via an eccentric oscillation bearing 42. The reducer 40 is composed of, for example, a pair of axially adjacent internal planetary gear mechanisms 40a. The pair of internal planetary gear mechanisms 40a are arranged so as to fit within the overall width of the assist motor 15 in the axial direction and so as to overlap the assist motor 15 as viewed in the radial direction. Each internal planetary gear mechanism 40a is a mechanism including an input gear (ring gear, internal gear) 41 and an output gear (planetary gear, external gear) 45 that meshes with the inner gear teeth of the input gear 41. For example, a mechanism disclosed by the present applicant in Japanese Patent Publication No. 6910197 can be suitably used.

[0019] When a precession force is generated in the internal planetary gear mechanism 40a, a thrust force is generated in the output gear 45. Due to the influence of this thrust force, there is a risk that the swing bearing 42 provided on the input gear 41 will come off the input gear 41. In particular, in an output range with a large torque exceeding 50 Nm, the thrust force of the output gear 45 is large, and the above-mentioned influence also becomes large. In this embodiment, as a means for suppressing the influence of the thrust force of the output gear 45, thrust receivers (e.g., circlips) 40b that restrict axial movement of the swing bearing 42 are attached to both axial sides of the inner periphery of the rotor 15a.

[0020] The rotor 15a is attached to the right case body 13 via a pair of support rings 16 in the axial direction. The rotor 15a is supported by the left and right support rings 16 via rotor bearings 16a, respectively. A pair of swing bearings 42 are arranged axially between the pair of rotor bearings 16a. Axially adjacent rotor bearings 16a and swing bearings 42 are in contact with each other via thrust plates 16b. A thrust receiver 40b attached to the inner periphery of the rotor 15a is arranged axially outward of each rotor bearing 16a. Each thrust receiver 40b is in contact with the adjacent rotor bearing 16a from the axial outside, thereby receiving the thrust force of the swing bearing 42 via the rotor bearing 16a and thrust plate 16b.

[0021] The pedal crankshaft 3 has base ends of left and right pedal crank arms 2a fixed to its left and right ends so as to rotate integrally with it. The shafts of the left and right pedals 2 are fixed to the distal ends of the left and right pedal crank arms 2a, respectively. A cylindrical transmission tube 17 is supported on the outer periphery of the pedal crankshaft 3. The transmission tube 17 is divided axially within the right case body 13. The left side of the transmission tube 17 serves as a sensor shaft 18 that is inserted into the left case body 12, and the right side of the transmission tube 17 serves as an output shaft (unit output member) 19 that is inserted into the right case body 13.

[0022] An expanded diameter portion 19a is formed at the left end of the output shaft 19, surrounding the outer periphery of the right end of the sensor shaft 18 with a gap therebetween. Reference numeral 19b in the figure denotes a flange-shaped stepped wall formed radially at the base end (right end) of the expanded diameter portion 19a. A first one-way clutch 26 is disposed between the inner circumferential surface of the expanded diameter portion 19a and the outer circumferential surface of the right end of the sensor shaft 18. The right end of the output shaft 19 protrudes to the right of the right bearing portion 23 (outside the case), and a drive sprocket 31 is attached to this right end so as to rotate integrally with the right end. The drive sprocket 31, together with a driven sprocket 32 ​​attached to the rear wheel 7 (drive wheel) and an endless drive chain 33 wound around both sprockets 31, 32, are included in a chain-type power transmission mechanism 34 that connects the pedal crankshaft 3 and the rear wheel 7.

[0023] The inner periphery of the left end (one axial end) of the sensor shaft 18 is supported by being fitted to the outer periphery of the left side of the pedal crankshaft 3 by a spline or the like. The sensor shaft 18 can rotate integrally with the pedal crankshaft 3 in both forward and reverse rotation directions. The inner periphery of the right end (the other axial end) of the sensor shaft 18 is supported via a needle bearing 27 on the outer periphery of a left-right intermediate portion (not limited to the center portion) of the pedal crankshaft 3 so as to be relatively rotatable. The needle bearing 27 is located in the intermediate portion of the pedal crankshaft 3 in the axial direction (lengthwise direction) and between the outer peripheral protrusions of the pedal crankshaft 3, and therefore has a half-split structure and is attached to the pedal crankshaft 3. By disposing the needle bearing 27 between the end of the sensor shaft 18 and the pedal crankshaft 3, runout of the end of the sensor shaft 18 is suppressed, improving the accuracy of torque detection (described later) and the accuracy of operation of the first one-way clutch 26. The right end of the sensor shaft 18 is disposed inside the expanded diameter portion 19a of the output shaft 19. The outer periphery of the right end of the sensor shaft 18 is supported on the inner periphery of the expanded diameter portion 19a of the output shaft 19 via a first one-way clutch 26.

[0024] When the pedal crankshaft 3 attempts to rotate relative to the output shaft 19 in the forward direction (the direction that moves the bicycle 1 forward), the first one-way clutch 26 enables torque to be transmitted from the pedal crankshaft 3 to the output shaft 19, allowing the bicycle 1 to travel using the rider's pedaling force. On the other hand, when the output shaft 19 attempts to rotate relative to the pedal crankshaft 3 in the forward direction (i.e., when the pedal crankshaft 3 attempts to rotate relative to the output shaft 19 in the reverse direction), the cam built into the first one-way clutch 26 does not engage and the first one-way clutch 26 spins freely, making it impossible to transmit torque.

[0025] A cylindrical reducer output member 47 that supports an output gear 45 of the reducer 40 is disposed on the inner peripheral side of the reducer 40. The reducer output member 47 is either formed integrally with the output gear 45 or has a configuration in which a separate output gear 45 is fixed integrally thereto. The reducer output member 47 is disposed so as to surround the outer periphery of the output shaft 19 with a gap therebetween. A second one-way clutch 28 is disposed between the inner peripheral surface of the reducer output member 47 and the outer peripheral surface of the output shaft 19.

[0026] The second one-way clutch 28 enables the assist torque of the assist motor 15 to be transmitted from the reducer output member 47 to the output shaft 19. When the reducer output member 47 attempts to rotate relative to the output shaft 19 in the forward direction (the direction that moves the bicycle 1 forward), the cam built into the second one-way clutch 28 engages, enabling the torque to be transmitted to the output shaft 19. This makes it possible to impart the assist torque of the assist motor 15 to the output shaft 19. On the other hand, if the output shaft 19 attempts to rotate at a speed exceeding the legally permitted speed (for example, 24 km / h), a command is output from the control board 36 to the assist motor 15 not to generate torque. As a result, the rotor 15, the reducer 40, and the reducer output member 47 do not rotate, the built-in cam of the second one-way clutch 28 does not engage and spins freely, and the assist motor 15 does not assist the pedal force.

[0027] When a rider pedals 2 to ride bicycle 1, the driving force of pedal crankshaft 3 is transmitted in this order to sensor shaft 18, first one-way clutch 26, and output shaft 19, and then to rear wheel 7 via chain transmission mechanism 34. At this time, when assist motor 15 rotates forward, the driving force is transmitted to reducer output member 47 via reducer 40, and then to output shaft 19 via second one-way clutch 28, assisting in reducing the pedal effort.

[0028] In the assist drive unit 10, it is possible to use one-way clutches 26, 28 of the same type and shape but with different capacities, which not only reduces costs but also makes it possible to provide an electric drive unit 10 with a compact single-axis structure by arranging a pair of one-way clutches 26, 28 in double rows. The first one-way clutch 26 and the second one-way clutch 28 are arranged side by side in the axial direction (adjacent to each other with the step wall 19b of the expanded diameter portion 19a sandwiched between them). The first one-way clutch 26 and the second one-way clutch 28 are arranged so as to fit within the overall width of the assist motor 15 in the axial direction. The first one-way clutch 26 and the second one-way clutch 28 are arranged so that their entirety overlaps with the assist motor 15 when viewed in the radial direction.

[0029] When the bicycle 1 coasts with the pedals 2 stopped, the chain transmission mechanism 34 does not rotate due to a one-way clutch located on the shaft of the rear wheel 7. When the bicycle 1 is stopped coasting and attempts are made to rotate the pedal crankshaft 3 in the reverse direction relative to the pedals 2, the built-in cam of the first one-way clutch 26 does not engage and spins freely, making it impossible to transmit torque.

[0030] A magnetic alloy ribbon 35a is wound integrally around the outer circumferential surface of the axially intermediate portion of the sensor shaft 18. A torque detection coil 35b, supported by the left case body 12, is disposed on the outer circumferential side of the ribbon 35a. The ribbon 35a and the torque detection coil 35b constitute a magnetostrictive torque sensor 35. That is, a torque difference between both axial ends of the sensor shaft 18 generates shear strain in the ribbon 35a, and the torque detection coil 35b detects a change in the magnetic permeability of the ribbon 35a due to this strain, thereby detecting the torque acting on the sensor shaft 18.

[0031] Torque is input to the left end of the sensor shaft 18 by the pedal crankshaft 3, and this torque is output from the right end of the sensor shaft 18 to the output shaft 19 via the first one-way clutch 26. At this time, if the magnetostrictive torque sensor 35 detects torque equal to or greater than a specified value, the assist motor 15 is driven to apply an assist torque to the output shaft 19. This reduces the rotational torque of the pedal crankshaft 3 and, ultimately, the pedaling force.

[0032] The drive of the assist motor 15 is controlled by a control device 36, which includes an MCU (Management Controller Unit) and PDU (Power Drive Unit), housed in the left case body 12. The control device 36 outputs a control signal to the PDU to drive the assist motor 15 based on inputs from a magnetostrictive torque sensor 35 and a rotation sensor (not shown) that detects the rotation of the pedal crankshaft 3. When the speed of the bicycle 1 is below a specified value and a predetermined or greater forward torque of the pedal crankshaft 3 is detected, the control device 36 drives the assist motor 15 to assist the pedaling force.

[0033] As explained above, the assist drive unit 10 in the above embodiment is an assist drive unit 10 that applies assist torque to the pedal crankshaft 3 from the assist motor 15 that is arranged coaxially with the pedal crankshaft 3, and includes a unit output member 19 that is arranged coaxially with the pedal crankshaft 3 and outputs driving force to the outside of the unit, and is capable of transmitting torque when the pedal crankshaft 3 rotates in the vehicle traveling direction relative to the unit output member 19 (relative rotation in the forward direction), and when the pedal crankshaft 3 rotates in the direction opposite to the vehicle traveling direction relative to the unit output member 19 (relative rotation in the reverse direction), the unit output member 19 rotates idly and transmits torque. the first one-way clutch 26 and the second one-way clutch 28 are arranged coaxially with the pedal crankshaft 3, and are arranged side by side in the axial direction of the pedal crankshaft 3, and are further arranged so as to overlap with the assist motor 15 when viewed radially. According to this configuration, the first one-way clutch 26, which allows the pedal crankshaft 3 to rotate in the reverse direction, and the second one-way clutch 28, which transmits assist torque, are arranged coaxially with each other, and both one-way clutches are arranged within the axial width of the assist motor 15, which allows the related parts to be arranged compactly and the entire unit to be made smaller.

[0034] The assist drive unit 10 is provided with a sensor shaft 18 that is arranged coaxially with the pedal crankshaft 3 and adjacent to the unit output member 19 in the axial direction, and one axial end of the sensor shaft 18 is supported by the pedal crankshaft 3 so as to be rotatable integrally with it, and the other axial end is supported by the pedal crankshaft 3 via a needle bearing 27 so as to be rotatable relative to it, and a first one-way clutch 26 is supported on the outer periphery of the other axial end of the sensor shaft 18. According to this configuration, the sensor shaft 18 is provided with one axial end fixed to the pedal crankshaft 3 and the other axial end supported via a needle bearing 27, and by supporting the first one-way clutch 26 on the outer periphery of the other axial end of the sensor shaft 18, the first one-way clutch 26 is supported with high rigidity and twisting between the two axial ends of the sensor shaft 18 is not hindered, allowing for good torque detection based on the twisting of the sensor shaft 18.

[0035] The assist drive unit 10 is provided with a reducer 40 that is positioned on the inner periphery of the assist motor 15 and that is arranged at a position that overlaps with the assist motor 15 when viewed in the radial direction. According to this configuration, the reducer 40 is disposed on the inner periphery of the assist motor 15 and within the axial width of the assist motor 15, thereby allowing the related parts to be disposed compactly and the overall unit to be made smaller.

[0036] In the assist drive unit 10, the assist motor 15 is an inner rotor type, and an internal gear 41 of a reducer 40 is provided on the inner periphery of a rotor 15a of the assist motor 15. According to this configuration, the internal gear 41 of the reducer 40 is provided on the inner periphery of the inner rotor 15a of the assist motor 15, so that the input shaft for the reducer 40 can also be used as the rotor shaft to which the magnets are attached in the assist motor 15. Furthermore, by using a general material such as S45C as the material for the rotor 15a, it can be used as a back yoke for the magnetic path of the electromagnetic part.

[0037] In the above-mentioned assist drive unit 10, the reducer 40 comprises a pair of axially adjacent internal planetary gear reducers 40a, and the internal gears 41 of each of the pair of internal planetary gear reducers 40a are supported on the inner periphery of the integral rotor 15a via respective eccentric oscillation bearings 42, and thrust receivers 40b that restrict axial movement of the eccentric oscillation bearings 42 are attached to both axial sides of the inner periphery of the rotor 15a. With this configuration, operation of a pair of axially adjacent internal planetary gear reducers 40a generates a precession force, which acts on the output gear 45. This influence may cause the eccentric oscillation bearing 42 provided on the input gear 41 (internal gear 41) to come out of the input gear 41. As a means for suppressing this influence, for example, ordinary circlips may be provided as thrust receivers 40b on both axial sides of the eccentric oscillation bearing 42, thereby suppressing the influence of the thrust force of the output gear 45.

[0038] The present invention is not limited to the above-described embodiment. For example, the assist device of the embodiment may be mounted on a type of bicycle (including three-wheeled and four-wheeled) different from that shown in FIG. The configurations in the above-described embodiments are merely examples of the present invention, and various modifications are possible within the scope of the gist of the present invention, such as replacing the components of the embodiments with well-known components. [Explanation of symbols]

[0039] 1. Bicycle 3 pedal crankshaft 10 Assist drive unit 15 Assist motor 15a rotor 18 Sensor shaft 19 Output shaft (unit output member) 26 First one-way clutch 27 needle bearing 28 Second one-way clutch 40 Reducer 40a internal planetary gear reducer 41 Internal gear 42 bearings 47 Reducer output member (assist output member)

Claims

1. An assist drive unit (10) that applies an assist torque to a pedal crankshaft (3) from an assist motor (15) that is arranged coaxially with the pedal crankshaft (3), a unit output member (19) arranged coaxially with the pedal crankshaft (3) and outputting a driving force to the outside of the unit; a first one-way clutch (26) that enables torque transmission when the pedal crankshaft (3) rotates relative to the unit output member (19) in the vehicle traveling direction, and that idles and disables torque transmission when the pedal crankshaft (3) rotates relative to the unit output member (19) in the direction opposite to the vehicle traveling direction; an assist output member (47) that is arranged coaxially with the unit output member (19) and outputs the assist torque of the assist motor (15); a second one-way clutch (28) that can transmit the assist torque when the assist output member (47) rotates relative to the unit output member (19) in the vehicle traveling direction, The first one-way clutch (26) and the second one-way clutch (28) are arranged coaxially with the pedal crankshaft (3), arranged side by side in the axial direction of the pedal crankshaft (3), and further arranged in a position overlapping with the assist motor (15) when viewed radially, forming an assist drive unit.

2. a sensor shaft (18) arranged coaxially with the pedal crankshaft (3) and adjacent to the unit output member (19) in the axial direction; 2. An assist drive unit as described in claim 1, wherein one axial end of the sensor shaft (18) is supported on the pedal crankshaft (3) so as to be rotatable integrally therewith, and the other axial end is supported on the pedal crankshaft (3) so as to be rotatable relative to the pedal crankshaft (3) via a needle bearing (27), and the first one-way clutch (26) is supported on the outer periphery of the other axial end of the sensor shaft (18).

3. 3. The assist drive unit according to claim 1, further comprising a reducer (40) located on the inner periphery of the assist motor (15) and arranged in a position overlapping with the assist motor (15) when viewed from the radial direction.

4. The assist motor (15) is an inner rotor type, 4. The assist drive unit according to claim 3, wherein an internal gear (41) of the reducer (40) is provided on the inner periphery of a rotor (15a) of the assist motor (15).

5. The reducer (40) includes a pair of internal planetary gear reducers (40a) adjacent to each other in the axial direction, The internal gear (41) of each of the pair of internal planetary gear reducers (40a) is supported on the inner periphery of the integral rotor (15a) via an eccentric swing bearing (42), 5. An assist drive unit according to claim 4, wherein thrust bearings (40b) for restricting axial movement of the eccentric swing bearing (42) are attached to both axial sides of the inner periphery of the rotor (15a).

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