TW202229094A - Electric assist driving unit and bicycle capable of facilitating assembly of components at the time of manufacture - Google Patents

Abstract

The electric auxiliary drive unit includes a crankshaft, a housing, an electric motor and a reduction gear. The housing is radially supported on the crankshaft via the first bearing. The electric motor and the reduction gear are arranged in the space between the crankshaft and the housing. Electric motors have stators and rotors. The stator is fixed to the housing. The rotor is radially supported on the crankshaft via a second bearing. The rotor rotates according to the load applied to the crankshaft. The speed reducer decelerates the rotation of the rotor and outputs it to the crankshaft.

Description

Electric Auxiliary Drive Units and Bicycles

The present invention relates to an electric auxiliary drive unit and a bicycle.

Conventionally, bicycles including an electric auxiliary drive unit having an electric motor and a speed reducer are known. The electric auxiliary drive unit drives the electric motor to assist the rotation of the pedals when the load on the user is large, such as when the bicycle is started or when the bicycle is running uphill. A conventional electric auxiliary drive unit is described in, for example, Japanese Patent Application Laid-Open No. 6637997.

The electric auxiliary drive unit has a structure in which an electric motor and a speed reducer are accommodated in a space between a crankshaft connected to a pedal of a bicycle and a housing of the electric auxiliary drive unit. However, in the structure of the conventional electric auxiliary drive unit, the rotor of the electric motor is supported with respect to the casing. As a result, the assembly structure of the electric motor and the speed reducer with respect to the crankshaft and the housing becomes complicated. In addition, since the diameter of the bearing supporting the rotor with respect to the casing is large, it is difficult to reduce the size and weight of the electric auxiliary drive unit.

An object of the present invention is to provide an electric auxiliary drive unit which is easy to assemble components at the time of manufacture, and which can be easily reduced in size and weight.

An exemplary embodiment of the present invention is an electric auxiliary drive unit that utilizes a driving force of an electric motor to assist rotation by human power, including: a crank shaft that is rotated around a central axis by human power; and a housing that The crankshaft is supported in the radial direction via a first bearing, and an electric motor and a speed reducer are arranged in a space between the crankshaft and the housing. The electric motor includes a stator fixed to the housing; a circuit board that supplies a drive current to the stator in accordance with a load applied to the crankshaft; and a rotor that is rotated by the drive current from the stator The magnetic field rotates around the above-mentioned central axis. The speed reducer decelerates the rotation of the rotor and outputs the output to the crankshaft, and the rotor is radially supported by the crankshaft via a second bearing.

An exemplary embodiment of the present invention is a bicycle in which the above-described electric auxiliary drive unit is included.

According to the exemplary embodiment of the present invention, the electric auxiliary drive unit can be easily manufactured. In addition, it is easy to reduce the size and weight of the electric auxiliary drive unit. Furthermore, a bicycle including the above-described electric auxiliary drive unit can be realized. Therefore, the electric auxiliary drive unit mounted on the bicycle can be easily manufactured. In addition, it is easy to reduce the size and weight of the electric auxiliary drive unit mounted on the bicycle.

The foregoing and other features, elements, steps, features, and advantages of the present invention may be more clearly understood in light of the following detailed description of preferred embodiments of the present invention, with reference to the accompanying drawings.

Exemplary embodiments of the present invention will be described below with reference to the accompanying drawings.

＜1. About bicycles＞ FIG. 1 is a schematic diagram of a bicycle 100 including an electrically assisted drive unit 1 according to an embodiment of the present invention. As shown in FIG. 1 , the bicycle 100 includes a front wheel 110 , a rear wheel 120 , a pedal 130 and a roller chain 140 . The pedals 130 are respectively arranged on both side surfaces of the bicycle 100 . Hereinafter, one of the rotational directions of the pedal 130 is referred to as a "forward direction". When the user pushes the pedal 130 in the forward direction, the rotational motion of the pedal 130 is transmitted to the rear wheel 120 via the roller chain 140 . Thereby, the rear wheel 120 rotates, and the bicycle 100 travels forward by the rotation of the rear wheel 120 and the front wheel 110 .

In addition, the bicycle 100 includes the electric auxiliary drive unit 1 . Thereby, the electric auxiliary drive unit 1 mounted on the bicycle 100 can be easily manufactured. In addition, it is easy to reduce the size and weight of the electric assist drive unit 1 mounted on the bicycle 100 . The electric auxiliary drive unit 1 is arranged between pedals 130 arranged on both sides of the bicycle 100 . In addition, the electric auxiliary drive unit 1 is arranged inside the chain cover 141 which covers the roller chain 140 . When the load on the pedal 130 is large, such as at the time of starting or running uphill, the electric auxiliary drive unit 1 supplies the pedal 130 with a rotational driving force in the forward direction. As a result, the user's force of stepping on the pedal 130 is reduced. As a result, the user can drive the bicycle 100 with ease.

<2. Electric auxiliary drive unit> Next, the configuration of the electric assist drive unit 1 will be described.

FIG. 2 is a side view of the electric auxiliary drive unit 1 . FIG. 3 is a longitudinal sectional view of the electric auxiliary drive unit 1 . The electric assist drive unit 1 is a device that assists the rotational movement of the pedal 130 by human power using the driving force of the electric motor 40 . That is, the electric assist drive unit 1 assists the rotation by human power using the driving force of the electric motor 40 . The electric auxiliary drive unit 1 includes a crankshaft 10 , a housing 20 , an electric motor 40 and a speed reducer 50 . As shown in FIGS. 2 and 3 , the electric auxiliary drive unit 1 includes a crankshaft 10 , a housing 20 , a torque sensor 30 , a motor 40 , a speed reducer 50 , a one-way clutch 60 and a sprocket 70 .

Hereinafter, a direction parallel to the central axis of the crankshaft 10 is referred to as an “axial direction”, a direction orthogonal to the central axis is referred to as a “radial direction”, and a direction along an arc centering on the central axis is referred to as called "circumferential". However, the above-mentioned "parallel direction" also includes a substantially parallel direction. In addition, the above-mentioned "orthogonal direction" also includes a substantially orthogonal direction.

The crankshaft 10 is a cylindrical member extending along the central axis 9 . Both ends in the axial direction of the crankshaft 10 protrude to the outside of the housing 20 . The crankshaft 10 is rotatably supported with respect to the frame 150 . In the present embodiment, as shown in FIG. 2 , the crankshaft 10 is rotatably supported by the frame 150 of the bicycle 100 via a pair of bearings 80 . Further, pedals 130 are fixed to both ends of the crankshaft 10 in the axial direction, respectively. The electric auxiliary drive unit 1 is attached to the bicycle 100 having the pedals 130 , and the crankshaft 10 is rotated by the pedaling force from the pedals 130 . More specifically, when the user of the bicycle 100 pedals the pedals 130 , the pedals 130 and the crankshaft 10 rotate around the center axis 9 by the pedaling force (human power). That is, the crankshaft 10 is rotated around the central axis 9 by manpower. Thereby, the electric assist mechanism can be realized in the bicycle 100 .

The casing 20 is a case that accommodates the electric motor 40 and the reduction gear 50 therein. As shown in FIGS. 2 and 3 , the housing 20 includes a motor housing 21 , a speed reducer housing 22 and an end cover 23 . The end cover 23 is located on one side in the axial direction of the motor case 21 . The speed reducer housing 22 is located on the other side in the axial direction than the motor housing 2121 . The motor case 21 , the reducer case 22 and the end cover 23 are fixed to each other by bolts 24 .

In addition, the housing 20 of this embodiment has the partition part 27 . The partition plate portion 27 expands radially inward from the inner peripheral surface of the housing 20 . The partition part 27 has a plate shape and an annular shape. The motor 40 is located on one side in the axial direction of the diaphragm portion 27 . The speed reducer 50 is located on the other side in the axial direction of the partition plate portion 27 .

A pair of first bearings 81 are sandwiched radially between the crankshaft 10 and the housing 20 . The housing 20 is supported by the crankshaft 10 via the first bearing 81 . That is, the housing 20 is supported by the crankshaft 10 via the first bearing 81 in the radial direction. Therefore, the housing 20 and the crankshaft 10 can rotate relative to each other. In addition, as shown in FIG. 2 , the housing 20 has a rotation preventing portion 25 . The anti-rotation portion 25 protrudes radially outward from the outer peripheral surface of the housing 20 . When the bicycle 100 is running, the anti-rotation portion 25 is in contact with the frame 150 in the circumferential direction. That is, the housing 20 has the anti-rotation portion 25 that is in contact with the frame 150 . Thereby, the rotation of the housing 20 about the center axis 9 is stopped.

In this way, in the configuration of the present embodiment, the crankshaft 10 is directly supported by the frame 150 without passing through the casing 20 . Therefore, the housing 20 is not required to have strength for supporting the crankshaft 10 . Therefore, a lower strength material can be used for the housing 20 . For example, the case 20 may be made of resin to reduce the weight of the case 20 . However, the material of the casing 20 may be metal such as aluminum.

The torque sensor 30 is a sensor that detects the load applied to the crankshaft 10 . The torque sensor 30 is provided at the radially inner end portion of the motor housing 21 . The torque sensor 30 detects the skew of the crankshaft 10 in a non-contact manner, and converts the skew amount into a torque value. The torque sensor 30 inputs a detection signal indicating the torque value of the crankshaft 10 to the circuit board 42 to be described later. That is, the electric auxiliary drive unit 1 has the torque sensor 30 which detects the torque of the crankshaft 10 and inputs the detection signal to the circuit board 42 .

The electric motor 40 is a power source that generates a driving force for assisting human power. The electric motor 40 is arranged in the space between the crankshaft 10 and the housing 20 . The motor 40 is located on one side of the speed reducer 50 in the axial direction. As shown in FIG. 3 , the motor 40 includes a stator 41 , a circuit board 42 and a rotor 43 .

The stator 41 is the stator of the electric motor 40 . The stator 41 is fixed to the casing 20 . In the present embodiment, the stator 41 is fixed to the motor casing 21 . The stator 41 has a stator core 411 and a plurality of coils 412 . The stator core portion 411 is formed of a magnetic body such as a laminated steel plate. The stator core portion 411 has a plurality of pole teeth protruding radially outward. The plurality of pole teeth are arranged at equal intervals in the circumferential direction. The coil 412 is composed of a wire wound around the pole teeth.

The circuit board 42 is a board on which a circuit for supplying a drive current to the coil 412 of the stator 41 is mounted. The circuit board 42 is electrically connected to the coil 412 , the torque sensor 30 , and a battery (not shown). The circuit board 42 acquires a detection signal representing the torque of the crankshaft 10 from the torque sensor 30 . In addition, a preset torque threshold value is stored in a memory mounted on the circuit board 42 .

The circuit board 42 does not supply the drive current to the coil 412 when the torque value indicated by the detection signal acquired from the torque sensor 30 is smaller than the aforementioned threshold value. The circuit board 42 supplies a drive current to the stator 41 when the torque indicated by the detection signal is equal to or greater than a predetermined threshold value. More specifically, when the torque value indicated by the detection signal acquired from the torque sensor 30 becomes equal to or greater than the above-described threshold value, the circuit board 42 generates a drive current corresponding to the torque value using the electric power supplied from the battery, and supplies it to the coil 412. That is, the circuit board 42 supplies a drive current to the stator 41 according to the load applied to the crankshaft 10 . Thereby, the torque can be controlled by the electric assist drive unit 1 .

The rotor 43 is the rotor of the electric motor 40 . A second bearing 82 is radially interposed between the crankshaft 10 and the rotor 43 . The rotor 43 is supported by the crankshaft 10 via the second bearing 82 . That is, the rotor 43 is supported by the crankshaft 10 via the second bearing 82 in the radial direction. Therefore, the rotor 43 can be rotated around the central axis 9 at a rotational speed different from that of the crankshaft 10 .

The rotor 43 has a rotor yoke 431 and a plurality of magnets 432 fixed to the rotor yoke 431 . The rotor yoke portion 431 is formed of a magnetic body such as iron. The plurality of magnets 432 are permanent magnets. The plurality of magnets 432 are located radially outside the stator 41 . That is, the electric motor 40 of this embodiment is an outer rotor type electric motor. The plurality of magnets 432 are arranged annularly so that N poles and S poles are alternately arranged in the circumferential direction. The radially outer end surface of the pole teeth and the radially inner surface of the magnet 432 face each other with a small gap in the radial direction. Since the electric motor 40 is an outer rotor type electric motor, the inertia moment of the electric motor 40 can be increased, and stable rotation can be realized.

When the motor 40 is driven, a drive current is supplied from the circuit board 42 to the coils 412 of the stator 41 . Thereby, a rotating magnetic field is generated in the stator core portion 411 . Then, a circumferential torque is generated between the stator 41 and the rotor 43 due to the magnetic attraction force and the magnetic repulsion force between the stator core 411 and the plurality of magnets 432 . As a result, the rotor 43 rotates about the center axis 9 . That is, the rotor 43 is rotated around the central axis 9 by the rotating magnetic field generated from the stator 41 by the drive current.

The speed reducer 50 is a mechanism that decelerates the rotational motion of the rotor 43 and outputs it to the crankshaft 10 . FIG. 4 is a cross-sectional view of the electric auxiliary drive unit 1 viewed from the A-A position in FIG. 3 . In order to avoid complicating the drawing, in FIG. 4 , the hatching showing the cross section and the illustration of the teeth of each gear are omitted. The speed reducer 50 is arranged in the space between the crankshaft 10 and the housing 20 . The speed reducer 50 has an intermediate rotating body 51 , a fixed member, and an output rotating body 55 . In the present embodiment, as shown in FIGS. 3 and 4 , the speed reducer 50 includes an intermediate rotating body 51 , a plurality of planetary gears 52 , a fixed internal gear 53 , a movable internal gear 54 , and an output rotating body 55 .

The intermediate rotating body 51 is an annular member centered on the central axis 9 . The intermediate rotating body 51 is located on the other side in the axial direction of the rotor 43 . A third bearing 83 is radially interposed between the crankshaft 10 and the intermediate rotating body 51 . The intermediate rotating body 51 is supported by the crankshaft 10 via the third bearing 83 . Therefore, the intermediate rotating body 51 can be rotated around the central axis 9 at a rotational speed different from that of the crankshaft 10 .

In addition, the electric auxiliary drive unit 1 of the present embodiment includes the oil seal 28 . The oil seal 28 is located between the radially inner end portion of the partition plate portion 27 and the outer peripheral surface of the intermediate rotating body 51 . In this way, the lubricating oil used in the speed reducer 50 can be prevented from entering the motor 40 side.

The intermediate rotating body 51 is fixed to the rotor 43 . In the present embodiment, the rotor 43 and the intermediate rotating body 51 are fixed to each other by the bolts 56 . Therefore, when the motor 40 is driven, the intermediate rotating body 51 rotates around the central axis 9 together with the rotor 43 . The above-mentioned second bearing 82 and third bearing 83 are arranged at intervals in the axial direction. Thereby, the rotational postures of the rotor 43 and the intermediate rotating body 51 with respect to the crankshaft 10 are stabilized.

The plurality of planetary gears 52 are arranged at equal intervals in the circumferential direction on the radially outer side of the crankshaft 10 . As shown in FIG. 4 , in the speed reducer 50 of the present embodiment, eight planetary gears 52 are arranged around the crankshaft 10 . However, the number of planetary gears 52 included in the speed reducer 50 is not limited to eight. Each of the planetary gears 52 is supported by a planetary shaft 511 fixed to the intermediate rotating body 51 . The planetary shafts 511 extend in the axial direction. In addition, the fourth bearing 84 is interposed between the planetary shaft 511 and the planetary gear 52 . Therefore, the planetary gear 52 can rotate around the planetary shaft 511 . In addition, the planetary gear 52 revolves around the central axis 9 with the rotation of the intermediate rotating body 51 .

The planetary gear 52 has a plurality of first external teeth 521 and a plurality of second external teeth 522 on the outer peripheral surface. The plurality of first external teeth 521 are located on one side in the axial direction of the plurality of second external teeth 522 . The diameter of the first outer teeth 521 is larger than the diameter of the second outer teeth 522 . The number of the first external teeth 521 of the planetary gear 52 is different from the number of the second external teeth 522 of the planetary gear 52 .

The fixed internal tooth gear 53 is an annular gear centered on the central axis 9 . The fixed internally toothed gear 53 is an example of a "fixed member". The fixed internally toothed gear 53 is fixed to the inner peripheral surface of the housing 20 via a key 532 . That is, the fixing member is fixed to the casing 20 . Therefore, the fixed internally toothed gear 53 cannot rotate relative to the housing 20 . The fixed internal tooth gear 53 has a plurality of first internal teeth 531 on the inner peripheral surface. The first external teeth 521 of the planetary gear 52 mesh with the first internal teeth 531 of the fixed internal tooth gear 53 .

The movable internally toothed gear 54 is an annular gear centered on the central axis 9 . The movable internal-tooth gear 54 is located on the other side in the axial direction of the fixed internal-tooth gear 53 . In addition, the inner diameter of the movable internally toothed gear 54 is smaller than the inner diameter of the fixed internally toothed gear 53 . The movable internal tooth gear 54 has a plurality of second internal teeth 541 on the inner peripheral surface. The second outer teeth 522 of the planetary gear 52 mesh with the second inner teeth 541 of the movable inner tooth gear 54 . The number (number of teeth) of the first internal teeth 531 of the fixed internal tooth gear 53 is different from the number (number of teeth) of the second internal teeth 541 of the movable internal tooth gear 54 .

When the electric motor 40 is driven, the rotor 43 and the intermediate rotating body 51 rotate around the central axis 9 at the first rotational speed before deceleration. Along with this, the plurality of planetary gears 52 revolve around the central axis 9 in the circumferential direction. That is, the speed reducer 50 has the planetary gears 52 which mesh with the fixed internal gear 53 and the movable internal gear 54 and revolve around the central axis 9 with the rotation of the intermediate rotating body 51 . Thereby, the differential gear reducer can be attached to the electric auxiliary drive unit 1 . At this time, since the first outer teeth 521 of each planetary gear 52 mesh with the first inner teeth 531 of the fixed inner gear 53 , the planetary gears 52 rotate around the planetary shaft 511 . In addition, since the second external teeth 522 of each planetary gear 52 mesh with the second internal teeth 541 of the movable internal tooth gear 54 , the number of teeth of the first external teeth 521 and the first internal teeth 531 and the second external teeth 522 and The difference in the number of teeth of the second internal teeth 541 causes the movable internal tooth gear 54 to rotate about the central axis 9 with respect to the fixed internal tooth gear 53 . The rotational speed of the movable internally toothed gear 54 is a second rotational speed lower than the above-described first rotational speed.

The output rotor 55 is an annular member centered on the central axis 9 . The output rotor 55 has a flange 551 and a bush 552 . The flange 551 extends in a disk shape on the other side in the axial direction of the plurality of planetary gears 52 . The bush 552 protrudes in the axial direction from the radially inner end portion of the flange 551 toward the motor 40 side. The bush 552 has a cylindrical shape centered on the central axis 9 . That is, the output rotor 55 has the cylindrical bush 552 protruding toward the motor 40 in the axial direction. The bushing 552 is located radially inward of the plurality of planetary gears 52 . The radially outer end of the flange 551 and the movable internally toothed gear 54 are fixed to each other by bolts 57 . Therefore, the output rotor 55 rotates at the second rotational speed after deceleration around the central axis 9 together with the movable internally toothed gear 54 . That is, the output rotor 55 rotates at the decelerated rotational speed around the central axis 9 . In other words, with the rotation of the intermediate rotating body 51 , the output rotating body 55 rotates at a lower rotational speed than the intermediate rotating body 51 with respect to the fixed member. That is, the speed reducer 50 has a movable internal tooth gear 54 which has an annular shape centered on the central axis 9 and rotates together with the output rotary body 55 . In addition, the movable internally toothed gear 54 and the output rotary body 55 may be a single member.

The one-way clutch 60 is a mechanism that allows the relative rotation of the output rotor 55 with respect to the crankshaft 10 to be directed in only one direction. The one-way clutch 60 is located between the bush 552 of the output rotor 55 and the crankshaft 10 in the radial direction. That is, in the configuration of the present embodiment, the one-way clutch 60 is provided on the radially inner side of the bush 552 that is turned back toward the motor 40 of the output rotor 55 . That is, the electric auxiliary drive unit 1 further includes the one-way clutch 60 that transmits only one-way rotation about the center axis 9 between the output rotor 55 and the crankshaft 10 . Thereby, the electric auxiliary drive unit 1 can be miniaturized in the axial direction.

When the forward rotation speed of the crankshaft 10 is greater than the forward rotation speed of the output rotor 55 , the one-way clutch 60 allows the rotation. Therefore, when the motor 40 is not driven, the user of the bicycle 100 can rotate the crankshaft 10 via the pedal 130 without receiving resistance from the motor 40 .

However, the one-way clutch 60 prohibits the forward rotation speed of the output rotor 55 from being higher than the forward rotation speed of the crankshaft 10 . Therefore, when the motor 40 is driven and the forward rotation speed of the output rotor 55 catches up with the forward rotation speed of the crankshaft 10 , the crankshaft 10 rotates in the forward direction at the same rotation speed as the output rotor 55 . In this way, the one-way clutch 60 transmits only the one-way rotational movement centered on the central axis 9 from the output rotor 55 to the crankshaft 10 .

The sprocket 70 is a member for transmitting the rotation of the crankshaft 10 to the roller chain 140 . The sprocket 70 has a disk shape centered on the central axis 9 . The sprocket 70 is located outside the housing 20 . In addition, the sprocket 70 is fixed to the crankshaft 10 . The sprocket 70 has a plurality of external teeth 71 on the outer peripheral portion. The sprocket 70 is engaged with the roller chain 140 of the bicycle 100 via the external teeth 71 . That is, the electric auxiliary drive unit 1 has the sprocket 70 engaged with the chain of the bicycle 100 . When the crankshaft 10 is rotated by the pedaling force from the pedal 130 or the driving force from the electric motor 40 , the sprocket 70 also rotates about the center axis 9 . Thereby, the roller chain 140 is rotated between the sprocket 70 and the rear wheel 120 .

As described above, when the load on the crankshaft 10 is large, the electric auxiliary drive unit 1 drives the electric motor 40 and supplies the driving force to the crankshaft 10 . At this time, the speed reducer 50 decelerates the rotational motion output from the electric motor 40 , thereby increasing the torque and transmitting the torque to the crankshaft 10 . Thereby, the rotation of the crankshaft 10 by manpower can be assisted.

In particular, in the structure of this embodiment, the housing 20 is supported by the crankshaft 10 via the first bearing 81 . In addition, the rotor 43 of the electric motor 40 is also supported by the crankshaft 10 via the second bearing 82 . Therefore, each component can be assembled centering on the crankshaft 10 . Therefore, the electric auxiliary drive unit 1 can be easily manufactured.

In addition, in the structure of this embodiment, the rotor 43 is supported by the crankshaft 10 via the 2nd bearing 82, rather than being supported by the housing 20. In this way, compared with the case where the rotor 43 is supported by the casing 20 via the bearing, the second bearing 82 having a smaller diameter can be used. Therefore, it is easy to reduce the size and weight of the electric assist drive unit 1 .

In addition, in the configuration of the present embodiment, the intermediate rotating body 51 is also supported by the crankshaft 10 via the third bearing 83 instead of being supported by the casing 20 . In this way, compared with the case where the intermediate rotating body 51 is supported by the housing 20 via the bearing, the third bearing 83 having a smaller diameter can be used. Therefore, it is easy to reduce the size and weight of the electric assist drive unit 1 .

In addition, the electric auxiliary drive unit 1 of the present embodiment includes the one-way clutch 60 between the output rotor 55 and the crankshaft 10 . Therefore, when the load of the crankshaft 10 is smaller than the threshold value, the crankshaft 10 can be rotated only by human power without receiving resistance from the electric motor 40 . In addition, the circuit board 42 drives the electric motor 40 only when the load on the crankshaft 10 becomes equal to or greater than the threshold value. Therefore, when no assistance is required, the electric motor 40 can be stopped to suppress consumption of the battery.

<3. Modifications> An embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment. Hereinafter, various modification examples will be described. In addition, below, it demonstrates centering on the difference from the said embodiment. For the same parts as those in the above-described embodiment, overlapping descriptions are omitted.

<3-1. First modification example> FIG. 5 is a vertical cross-sectional view of the electric auxiliary drive unit 1 according to the first modification. The structure of the electric motor 40 of the electric auxiliary drive unit 1 of FIG. 5 is different from that of the above-described embodiment.

In the structure of FIG. 5 , the stator core portion 411 of the electric motor 40 has a plurality of pole teeth protruding radially inward. The plurality of pole teeth are arranged at equal intervals in the circumferential direction. The coil 412 is composed of a wire wound around the pole teeth. The plurality of magnets 432 are fixed to the outer peripheral surface of the rotor yoke 431 . The plurality of magnets 432 are located radially inside the stator 41 . The plurality of magnets 432 are arranged annularly so that N poles and S poles are alternately arranged in the circumferential direction. The radially inner end surface of the pole teeth and the radially outer surface of the magnet 432 face each other with a small gap in the radial direction.

As described above, the electric motor 40 of the electric auxiliary drive unit 1 may be an inner rotor type electric motor in which the magnet 432 of the rotor 43 is located radially inward of the stator 41 . Thereby, the electric motor 40 with good responsiveness can be installed in the electric auxiliary drive unit 1 .

<3-2. Second modification example> FIG. 6 is a longitudinal cross-sectional view of the electric auxiliary drive unit 1 according to the second modification. The structures of the electric motor 40 and the speed reducer 50 of the electric auxiliary drive unit 1 of FIG. 6 are different from those of the above-described embodiment.

In the structure of FIG. 6 , the stator 41 of the electric motor 40 has a substantially disk shape centered on the central axis 9 . The stator 41 has a plurality of coils (not shown) arranged in the circumferential direction. The magnetic core of each coil faces the axial direction. The rotor 43 includes a first rotor yoke 431a, a second rotor yoke 431b, a first magnet 432a, and a second magnet 432b. The first rotating yoke portion 431 a extends in the shape of a disk on one axial side of the stator 41 with the center axis 9 as the center. The second rotating yoke portion 431b extends in a disk shape with the center axis 9 as the center on the other side in the axial direction of the stator 41 .

The first magnet 432a is fixed to the surface on the other side in the axial direction of the first rotor yoke 431a. The second magnet 432b is fixed to the surface on one side in the axial direction of the second rotor yoke 431b. The first magnet 432a and the second magnet 432b are respectively in annular shapes centered on the central axis 9 . The surface of the first magnet 432a is axially opposed to the surface on one side of the stator 41 in the axial direction with a slight gap therebetween. The surface of the second magnet 432b is axially opposed to the surface on the other side in the axial direction of the stator 41 with a slight gap therebetween. On the surfaces of the first magnet 432a and the second magnet 432b, N poles and S poles are alternately magnetized in the circumferential direction.

In this way, the motor 40 of the electric auxiliary drive unit 1 may also be an axial gap type motor in which the magnets 432a and 432b of the stator 41 and the rotor 43 are axially opposed to each other. By using the electric motor 40 as an axial gap type, the axial dimension of the electric motor 40 can be suppressed as compared with the case where an outer rotor type or an inner rotor type electric motor having the same performance is used.

In particular, the motor 40 of the present embodiment has two magnets 432a and 432b arranged to sandwich the stator 41 therebetween. Thereby, the torque output from the electric motor 40 can be increased compared with the case where the magnets are arranged only on one side of the stator 41 .

The speed reducer 50 of the electric auxiliary drive unit 1 of FIG. 6 includes an intermediate rotating body 51 , a plurality of planetary rollers 52 , a non-rotating ring 53 , a rotatable ring 54 , and an output rotating body 55 .

The plurality of planetary rollers 52 are arranged at equal intervals in the circumferential direction on the radially outer side of the crankshaft 10 . Each of the planetary rollers 52 is supported by a planetary shaft 511 fixed to the intermediate rotating body 51 . The planetary shafts 511 extend in the axial direction. Each of the planetary rollers 52 can rotate around the planetary shaft 511 . In addition, the planetary rollers 52 revolve around the central axis 9 with the rotation of the intermediate rotating body 51 .

The planetary roller 52 has a first inclined surface 521 and a second inclined surface 522 on the outer peripheral surface. The first inclined surface 521 is located on one side in the axial direction of the second inclined surface 522 . The first inclined surface 521 is an inclined surface whose diameter decreases toward one side in the axial direction. The second inclined surface 522 is an inclined surface whose diameter decreases toward the other side in the axial direction.

The non-rotating ring 53 is an annular member centered on the central axis 9 . The non-rotating ring 53 is an example of a "fixed member". The non-rotating ring 53 is arranged along the inner peripheral surface of the housing 20 . The non-rotating ring 53 cannot rotate relative to the housing 20 . The inner peripheral surface of the non-rotating ring 53 includes a third inclined surface 531 . The third inclined surface 531 is an inclined surface whose diameter decreases toward one side in the axial direction.

The speed reducer 50 has a pressing mechanism 58 on one axial side of the non-rotating ring 53 . The pressing mechanism 58 presses the non-rotating ring 53 in the axial direction toward the rotatable ring 54 side. In the structure of FIG. 6 , the pressing mechanism 58 is constituted by a spring which can expand and contract in the axial direction and a pressure regulating cam which applies a pressing force proportional to the load torque. However, any one of the spring and the pressure regulating cam may be omitted. In addition, as the pressing mechanism 58, an elastic member other than a spring may be used. Due to the pressing force of the pressing mechanism 58 , the third inclined surface 531 of the non-rotating ring 53 is in contact with the first inclined surface 521 of the planetary roller 52 .

A thrust bearing 59 is arranged in a gap between the flange 551 of the output rotor 55 and the reducer housing 22 in the axial direction. The thrust bearing 59 supports the pressing force and reaction force in the axial direction of the pressing mechanism 58 through the housing 20 . Therefore, the pressing force of the pressing mechanism 58 does not affect members other than the above-described inclined surfaces.

The rotatable ring 54 is an annular member centered on the central axis 9 . The rotatable ring 54 is located on the other side in the axial direction of the non-rotatable ring 53 . The inner peripheral surface of the rotatable ring 54 includes a fourth inclined surface 541 . The fourth inclined surface 541 is an inclined surface whose diameter decreases toward the other side in the axial direction. The second inclined surface 522 of the planetary roller 52 is in contact with the fourth inclined surface 541 of the rotatable ring 54 . The inner diameter of the non-rotating ring 53 is slightly different from the inner diameter of the rotatable ring 54 .

When the electric motor 40 is driven, the rotor 43 and the intermediate rotating body 51 rotate around the central axis 9 at the first rotational speed before deceleration. Along with this, the plurality of planetary rollers 52 revolve in the circumferential direction around the central axis 9 . That is, the speed reducer 1 further includes the planetary rollers 52 which are in contact with the non-rotating ring 53 and the rotatable ring 54 and revolve around the central axis 9 with the rotation of the intermediate rotating body 51 . Therefore, a traction reducer can be installed in the electric auxiliary drive unit 1 . At this time, since the first inclined surface 521 of each planetary roller 52 is in contact with the third inclined surface 531 of the non-rotating ring 53 , the planetary roller 52 rotates around the planetary shaft 511 . In addition, since the second inclined surface 522 of each planetary roller 52 is in contact with the fourth inclined surface 541 of the rotatable ring 54, the second inclined surface 522 passes through the contact portion of the first inclined surface 521 and the third inclined surface 531. And the diameter difference of the contact part of the 4th inclined surface 541, the rotatable ring 54 rotates with respect to the non-rotatable ring 53 centering on the central axis 9. The rotational speed of the rotatable ring 54 is a second rotational speed lower than the above-described first rotational speed.

Furthermore, the rotatable ring 54 and the output rotating body 55 are fixed to each other. Therefore, the output rotor 55 rotates at the second rotational speed after deceleration around the center axis 9 together with the rotatable ring 54 . That is, the speed reducer 50 has a rotatable ring 54 which has an annular shape centered on the central axis 9 and rotates together with the output rotor 55 . In addition, the rotatable ring 54 and the output rotary body 55 may be a single member.

In addition, in the example of FIG. 6 , the first inclined surface 521 of the planetary roller 52 is in contact with the third inclined surface 531 of the non-rotating ring 53 . However, the structure is not limited to such a structure in which the inclined surfaces are in contact with each other, and a structure in which the inclined surfaces and the protrusions are in contact may be used. That is, in the contact portion of the planetary roller 52 and the non-rotating ring 53 , at least one surface of the planetary roller 52 and the non-rotating ring 53 may be an inclined surface whose diameter decreases as the distance from the rotatable ring 54 increases.

In addition, in the example of FIG. 6 , the second inclined surface 522 of the planetary roller 52 is in contact with the fourth inclined surface 541 of the rotatable ring 54 . However, the structure is not limited to such a structure in which the inclined surfaces are in contact with each other, and a structure in which the inclined surfaces and the protrusions are in contact may be used. That is, in the contact portion of the planetary roller 52 and the rotatable ring 54 , at least one of the surfaces of the planetary roller 52 and the rotatable ring 54 may be an inclined surface whose diameter decreases as it moves away from the non-rotating ring 53 . Thereby, the rotatable ring 54 can be relatively rotated with respect to the non-rotatable ring 53 .

<3-3. Third modification example> FIG. 7 is a vertical cross-sectional view of the electric auxiliary drive unit 1 according to the third modification. FIG. 8 is a cross-sectional view of the electric auxiliary drive unit 1 viewed from the position B-B in FIG. 7 . In order to avoid complicating the drawing, hatching representing the cross section is omitted in FIG. 8 . The structures of the electric motor 40 and the speed reducer 50 of the electric auxiliary drive unit 1 of FIGS. 7 and 8 are different from those of the above-described embodiment. However, since the structure of the electric motor 40 is the same as that of the second modification, the repeated description is omitted.

The speed reducer 50 of the electric auxiliary drive unit 1 of FIGS. 7 and 8 has an intermediate rotating body 51 , a flexible externally-toothed gear 52 , a fixed internal-toothed gear 53 , a movable internal-toothed gear 54 , and an output rotating body 55 .

The intermediate rotating body 51 of this modification includes a cam 512 . In FIG. 8 , the shape of the outer peripheral surface of the cam 512 when viewed in the axial direction is an ellipse. However, the shape of the outer peripheral surface of the cam 512 is not necessarily limited to an oval shape. The cam 512 may have a non-circular outer peripheral surface whose outer diameter (distance from the central axis 9 ) varies depending on the position in the circumferential direction. That is, the intermediate rotating body 51 includes the non-circular cam 512 whose outer diameter differs depending on the position in the circumferential direction.

The flexible externally toothed gear 52 is a thin-walled gear that can be flexibly deformed. The flexible externally toothed gear 52 has an annular shape and is located radially outside of the cam 512 . The flexible externally toothed gear 52 has a plurality of external teeth 523 on the outer peripheral surface. In addition, a flexible bearing 85 is interposed between the outer peripheral surface of the cam 512 and the flexible externally toothed gear 52 . The flexible bearing 85 is a bearing that can flexibly deform. Therefore, by the rotation of the cam 512 , the flexible externally toothed gear 52 is deflected in the radial direction via the flexible bearing 85 .

The fixed internal tooth gear 53 is an annular gear centered on the central axis 9 . The fixed internally toothed gear 53 is an example of a "fixed member". The fixed internally toothed gear 53 is fixed to the inner peripheral surface of the casing 20 . Therefore, the fixed internally toothed gear 53 cannot rotate relative to the housing 20 . The fixed internal tooth gear 53 has a plurality of first internal teeth 531 on the inner peripheral surface.

The movable internally toothed gear 54 is an annular gear centered on the central axis 9 . The movable internal-tooth gear 54 is located on the other side in the axial direction of the fixed internal-tooth gear 53 . The movable internal tooth gear 54 has a plurality of second internal teeth 541 on the inner peripheral surface. The number (number of teeth) of the first internal teeth 531 of the fixed internal tooth gear 53 is different from the number (number of teeth) of the second internal teeth 541 of the movable internal tooth gear 54 .

The inner ring of the flexible bearing 85 is in contact with the outer peripheral surface of the cam 512 . The outer ring of the flexible bearing 85 is in contact with the inner peripheral surface of the flexible externally toothed gear 52 . The flexible bearing 85 is deformed into an oval shape along the outer peripheral surface of the cam 512 . Therefore, the flexible externally toothed gear 52 is also deformed into an elliptical shape along the outer peripheral surface of the cam 512 . As a result, at two locations corresponding to both ends of the long axis of the ellipse, a part of the external teeth 523 of the flexible externally toothed gear 52 is pressed by the outer peripheral surface of the cam 512 via the flexible bearing 85 , thereby connecting with the fixed inner teeth. The first inner teeth 531 of the toothed gear 53 mesh with the second inner teeth 541 of the movable inner tooth gear 54 . At other positions in the circumferential direction, the outer teeth 523 do not mesh with the first inner teeth 531 and the second inner teeth 541 . That is, the speed reducer 50 further includes a ring-shaped externally toothed gear that is pressed by the outer peripheral surface of the cam 512 to flex and deform, and meshes with the fixed internal toothed gear 53 and the movable internal toothed gear 54 in a part of the circumferential direction . As a result, the electric auxiliary drive unit 1 can be equipped with the speed reducer 50 having the differential wave deceleration mechanism.

When the electric motor 40 is driven, the rotor 43 and the intermediate rotating body 51 rotate around the central axis 9 at the first rotational speed before deceleration. Along with this, the cam 512 also rotates at the first rotational speed around the central axis 9 . Then, the long axis of the above-mentioned ellipse of the flexible externally toothed gear 52 also rotates at the first rotational speed. Therefore, the meshing position of the external teeth 523 of the flexible externally-toothed gear 52 and the first internal teeth 531 of the fixed internal-toothed gear 53 also moves at the first rotational speed in the circumferential direction. In addition, the external teeth 523 of the flexible externally toothed gear 52 are also meshed with the second internal teeth 541 of the movable internal tooth gear 54. Therefore, due to the difference in the number of teeth between the first internal teeth 531 and the second internal teeth 541, the movable internal tooth gear 54 It rotates about the center axis 9 with respect to the fixed internally toothed gear 53 . The rotational speed of the movable internally toothed gear 54 is a second rotational speed lower than the above-described first rotational speed.

The movable internally toothed gear 54 and the output rotary body 55 are fixed to each other by bolts 57 . Therefore, the output rotor 55 rotates at the second rotational speed after deceleration around the central axis 9 together with the movable internally toothed gear 54 . That is, the speed reducer 50 has a movable internal tooth gear 54 which has an annular shape centered on the central axis 9 and rotates together with the output rotary body 55 . In addition, the movable internally toothed gear 54 and the output rotary body 55 may be a single member.

<3-4. Fourth modification example> FIG. 9 is a vertical cross-sectional view of the electric auxiliary drive unit 1 according to the fourth modification. The structures of the electric motor 40 and the speed reducer 50 of the electric auxiliary drive unit 1 of FIG. 9 are different from those of the above-described embodiment. However, since the structure of the electric motor 40 is the same as that of the first modification, the repeated description is omitted.

The speed reducer 50 of the electric auxiliary drive unit 1 of FIG. 9 has an intermediate rotating body 51 , a flexible externally toothed gear 52 , an internal toothed gear 53 , and an output rotating body 55 .

The intermediate rotating body 51 of this modification includes a cam 512 . The shape of the outer peripheral surface of the cam 512 when viewed in the axial direction is elliptical. However, the shape of the outer peripheral surface of the cam 512 is not necessarily limited to an oval shape. The cam 512 may have a non-circular outer peripheral surface whose outer diameter (distance from the central axis 9 ) varies depending on the position in the circumferential direction. That is, the speed reducer 50 includes the intermediate rotating body 51 fixed to the rotor 43 and including the non-circular cam 512 whose outer diameter varies depending on the position in the circumferential direction.

The flexible externally toothed gear 52 is a thin-walled gear that can be flexibly deformed. The flexible externally toothed gear 52 has a substantially cup-shaped outer shape. That is, the flexible externally toothed gear 52 has a cylindrical portion 524 and a circular plate portion 525 . The cylindrical portion 524 is located radially outward of the cam 512 . The circular plate portion 525 extends radially inward from the end portion on the other axial side of the cylindrical portion 524 .

The cylindrical portion 524 has a plurality of external teeth 523 . The cylindrical portion 524 has a plurality of external teeth 523 on the outer peripheral surface. In addition, a flexible bearing 85 is interposed between the outer peripheral surface of the cam 512 and the inner peripheral surface of the cylindrical portion 524 . The flexible bearing 85 is a bearing that can flexibly deform. Therefore, by the rotation of the cam 512 , the cylindrical portion 524 of the flexible externally toothed gear 52 is deflected in the radial direction via the flexible bearing 85 .

The internally toothed gear 53 is an annular gear centered on the central axis 9 . The internally toothed gear 53 is fixed to the casing 20 . More specifically, the internally toothed gear 53 is fixed to the inner peripheral surface of the casing 20 . Therefore, the internal gear 53 cannot rotate relative to the housing 20 . The internally toothed gear 53 has a plurality of internal teeth 531 on the inner peripheral surface. The number (number of teeth) of the external teeth 523 of the flexible externally toothed gear 52 is different from the number (number of teeth) of the internal teeth 531 of the internally toothed gear 53 .

The inner ring of the flexible bearing 85 is in contact with the outer peripheral surface of the cam 512 . The outer ring of the flexible bearing 85 is in contact with the inner peripheral surface of the cylindrical portion 524 of the flexible externally toothed gear 52 . The flexible bearing 85 is deformed into an oval shape along the outer peripheral surface of the cam 512 . Therefore, the cylindrical portion 524 of the flexible externally toothed gear 52 is also deformed into an elliptical shape along the outer peripheral surface of the cam 512 . As a result, at two locations corresponding to both ends of the long axis of the ellipse, a part of the external teeth 523 of the flexible externally toothed gear 52 is pressed by the outer peripheral surface of the cam 512 via the flexible bearing 85 , and thus interacts with the internal teeth. The inner teeth 531 of the gear 53 mesh with each other. At other positions in the circumferential direction, the outer teeth 523 do not mesh with the inner teeth 531 . That is, the speed reducer 50 has an externally-toothed gear that is pressed by the outer peripheral surface of the cam 512 to flex and deform, and meshes with the internally-toothed gear 53 in a part of the circumferential direction.

When the electric motor 40 is driven, the rotor 43 and the intermediate rotating body 51 rotate around the central axis 9 at the first rotational speed before deceleration. Along with this, the cam 512 also rotates at the first rotational speed around the central axis 9 . Then, the long axis of the above-mentioned ellipse of the cylindrical portion 524 of the flexible externally toothed gear 52 also rotates at the first rotational speed. Therefore, the meshing position of the external teeth 523 of the flexible externally toothed gear 52 and the internal teeth 531 of the internally toothed gear 53 also moves in the circumferential direction at the first rotational speed. In addition, the number of the external teeth 523 of the flexible externally toothed gear 52 is different from the number of the internal teeth 531 of the internally toothed gear 53 . Therefore, by this difference in the number of teeth, the flexible externally toothed gear 52 rotates about the center axis 9 with respect to the internally toothed gear 53 . The rotational speed of the flexible externally toothed gear 52 is a second rotational speed lower than the above-described first rotational speed.

The flexible externally toothed gear 52 and the output rotary body 55 are fixed to each other by bolts 57 . Therefore, the output rotary body 55 rotates together with the externally toothed gear. More specifically, the output rotor 55 rotates at the second rotational speed after deceleration around the central axis 9 together with the flexible externally toothed gear 52 . In addition, the flexible externally toothed gear 52 and the output rotary body 55 may be a single member. Thereby, a cup-shaped externally toothed gear can be realized in the speed reducer 50 .

<3-5. Fifth modification example> FIG. 10 is a vertical cross-sectional view of the electric auxiliary drive unit 1 according to the fifth modification. The structure of the speed reducer 50 of the electric auxiliary drive unit 1 of FIG. 10 is different from that of the above-described embodiment.

The speed reducer 50 of the electric auxiliary drive unit 1 of FIG. 10 has an intermediate rotating body 51 , a flexible externally-toothed gear 52 , an internal-toothed gear 53 , and an output rotating body 55 .

The intermediate rotating body 51 of this modification includes a cam 512 . The shape of the outer peripheral surface of the cam 512 when viewed in the axial direction is elliptical. However, the shape of the outer peripheral surface of the cam 512 is not necessarily limited to an oval shape. The cam 512 may have a non-circular outer peripheral surface whose outer diameter (distance from the central axis 9 ) varies depending on the position in the circumferential direction.

The flexible externally toothed gear 52 is a thin-walled gear that can be flexibly deformed. The flexible externally toothed gear 52 has a substantially hat-shaped outer shape. That is, the flexible externally toothed gear 52 has a cylindrical portion 524 and a circular plate portion 525 . The cylindrical portion 524 is located radially outward of the cam 512 . The circular plate portion 525 extends radially outward from the end portion on the one side in the axial direction of the cylindrical portion 524 . The disc portion 525 is fixed to the casing 20 . More specifically, the radially outer end portion of the disk portion 525 is fixed to the housing 20 .

The cylindrical portion 524 has a plurality of external teeth 523 . More specifically, the cylindrical portion 524 has a plurality of external teeth 523 on the outer peripheral surface. In addition, a flexible bearing 85 is interposed between the outer peripheral surface of the cam 512 and the inner peripheral surface of the cylindrical portion 524 . The flexible bearing 85 is a bearing that can flexibly deform. Therefore, by the rotation of the cam 512 , the cylindrical portion 524 of the flexible externally toothed gear 52 is deflected in the radial direction via the flexible bearing 85 .

The internally toothed gear 53 is an annular gear centered on the central axis 9 . A crossed roller bearing 86 is radially interposed between the housing 20 and the internally toothed gear 53 . The internally toothed gear 53 is supported by the casing 20 via the crossed roller bearing 86 . Therefore, the internally toothed gear 53 can rotate about the center axis 9 . The internally toothed gear 53 has a plurality of internal teeth 531 on the inner peripheral surface. The number (number of teeth) of the external teeth 523 of the flexible externally toothed gear 52 is different from the number (number of teeth) of the internal teeth 531 of the internally toothed gear 53 .

The inner ring of the flexible bearing 85 is in contact with the outer peripheral surface of the cam 512 . The outer ring of the flexible bearing 85 is in contact with the inner peripheral surface of the cylindrical portion 524 of the flexible externally toothed gear 52 . The flexible bearing 85 is deformed into an oval shape along the outer peripheral surface of the cam 512 . Therefore, the cylindrical portion 524 of the flexible externally toothed gear 52 is also deformed into an elliptical shape along the outer peripheral surface of the cam 512 . As a result, at two locations corresponding to both ends of the long axis of the ellipse, a part of the external teeth 523 of the flexible externally toothed gear 52 is pressed by the outer peripheral surface of the cam 512 via the flexible bearing 85 , and thus interacts with the internal teeth. The inner teeth 531 of the gear 53 mesh with each other. At other positions in the circumferential direction, the outer teeth 523 do not mesh with the inner teeth 531 .

When the electric motor 40 is driven, the rotor 43 and the intermediate rotating body 51 rotate around the central axis 9 at the first rotational speed before deceleration. Along with this, the cam 512 also rotates at the first rotational speed around the central axis 9 . Then, the long axis of the above-mentioned ellipse of the cylindrical portion 524 of the flexible externally toothed gear 52 also rotates at the first rotational speed. Therefore, the meshing position of the external teeth 523 of the flexible externally toothed gear 52 and the internal teeth 531 of the internally toothed gear 53 also moves in the circumferential direction at the first rotational speed. In addition, the number of the external teeth 523 of the flexible externally toothed gear 52 is different from the number of the internal teeth 531 of the internally toothed gear 53 . Therefore, by this difference in the number of teeth, the internally toothed gear 53 rotates about the center axis 9 with respect to the flexible externally toothed gear 52 . The rotational speed of the internally toothed gear 53 is a second rotational speed lower than the above-described first rotational speed.

The speed reducer 50 has an output rotary body 55 that rotates at a decelerated rotational speed around the central axis 9 . The internally toothed gear 53 and the output rotary body 55 are fixed to each other by bolts 57 . Therefore, the output rotary body 55 rotates together with the internally toothed gear 53 . More specifically, the output rotor 55 rotates at the second rotational speed after deceleration around the central axis 9 together with the internally toothed gear 53 . In addition, the flexible externally toothed gear 52 and the output rotary body 55 may be a single member. Thereby, the wave gear mechanism can be realized in the electric auxiliary drive unit 1 .

In the above-described fourth modification example, the internally-toothed gear 53 is fixed to the housing 20 , and the flexible externally-toothed gear 52 is rotated relative to the internally-toothed gear 53 at the second rotational speed after deceleration. On the other hand, in the fifth modification, the flexible externally toothed gear 52 is fixed to the housing 20 , and the internal toothed gear 53 is rotated relative to the flexible externally toothed gear 52 at the second rotational speed after deceleration. In this way, when the flexible externally-toothed gear 52 is used in the speed reducer 50 , either one of the flexible externally-toothed gear 52 and the internal-toothed gear 53 may be fixed to the housing 20 . Further, the other of the flexible externally toothed gear 52 and the internally toothed gear 53 may rotate at the second rotational speed together with the output rotary body 55 . Here, the second rotational speed is a rotational speed lower than that of the intermediate rotating body 51 . Thereby, the wave gear mechanism can be realized in the electric auxiliary drive unit 1 .

<3-6. Sixth modification example> FIG. 11 is a transverse cross-sectional view of the electric auxiliary drive unit 1 according to the sixth modification. The structures of the electric motor 40 and the speed reducer 50 of the electric auxiliary drive unit 1 of FIG. 11 are different from those of the above-described embodiment. However, the structure of the electric motor 40 is the same as that of the above-described second modification. In addition, the structure of the speed reducer 50 is the same as that of the above-mentioned fifth modification. In this way, the type of the electric motor 40 and the type of the reduction gear 50 can be arbitrarily combined.

<3-7. Seventh modification example> FIG. 12 is a side view of the electric auxiliary drive unit 1 of the seventh modification. The support structure of the electric auxiliary drive unit 1 of FIG. 12 with respect to the frame 150 of the bicycle 100 is different from that of the above-described embodiment.

In the example of FIG. 12 , the housing 20 is secured to the frame 150 of the bicycle 100 by means of bolts 26 . Thereby, the casing 20 is fixed to the frame 150 , and the casing 20 is supported by the frame 150 . As in the above-described embodiment, the first bearing 81 (see FIG. 3 ) is interposed in the radial direction between the crankshaft 10 and the housing 20 . The crankshaft 10 is supported by the casing 20 via the first bearing 81 . In the structure of this modification, since the housing 20 supports the crankshaft 10, the housing 20 needs strength compared with the above-mentioned embodiment. However, if the configuration of this modification is adopted, the bearing 80 of the above-described embodiment can be omitted. Therefore, the structure of the electric auxiliary drive unit 1 can be simplified.

<3-8. Other modifications> In the above-described embodiment and modification examples, the electric auxiliary drive unit 1 mounted on the bicycle 100 has been described. However, the electric auxiliary drive unit 1 of the present invention may also be installed in equipment other than a bicycle. For example, in an auxiliary suit, a reel of a fishing rod, etc., in order to assist manpower, the electric auxiliary drive unit of the present invention may be installed.

In addition, the shape of the fine part of the electric auxiliary drive unit may be different from the shape shown in each drawing of the present invention. In addition, the respective elements appearing in the above-described embodiments or modified examples may be appropriately combined within the range that does not cause inconsistency.

The invention can be used, for example, for electric auxiliary drive units and bicycles.

1: Electric auxiliary drive unit 9: Central axis 10: Crankshaft 20: Shell 21: Motor housing 22: reducer housing 23: End cap 24: Bolts 25: Anti-rotation part 26: Bolts 27: Partition 28: Oil seals 30: Torque sensor 40: Motor 41: Stator 411: stator core 412: Coil 42: circuit substrate 43: Rotor 431: Rotor yoke 431a: First rotor yoke 431b: Second rotor yoke 432: Magnet 432a: first magnet 432b: Second magnet 50: reducer 51: Intermediate rotating body 511: Planetary shaft 512: Cam 52: Planetary gear/flexible external gear/planet roller 521: First external tooth/first inclined surface 522: Second external tooth/second inclined surface 523: External teeth 524: Cylinder 525: Disc Department 53: Fixed internal gear/internal gear/non-rotating ring 531: First internal tooth/internal tooth/third inclined surface 532:Key 54: Movable internal gear/rotatable ring 541: Second inner tooth/fourth inclined surface 55: Output rotating body 551: Flange 552: Bushing 56: Bolts 57: Bolts 58: Pressing mechanism 59: Thrust bearing 60: One-way clutch 70: Sprocket 71: External teeth 80: Bearing 81: The first bearing 82: Second bearing 83: The third bearing 84: Fourth bearing 85: Flexible bearing 86: Crossed Roller Bearings 100: Bike 110: Front Wheel 120: rear wheel 130: Pedal 140: Roller chain 141: Chain Cover 150: Frame

FIG. 1 is a schematic diagram of a bicycle including an electric auxiliary drive unit. FIG. 2 is a side view of the electric auxiliary drive unit. 3 is a longitudinal sectional view of the electric auxiliary drive unit. FIG. 4 is a cross-sectional view of the electric auxiliary drive unit viewed from the A-A position in FIG. 3 . 5 is a vertical cross-sectional view of an electric auxiliary drive unit according to a first modification. 6 is a longitudinal cross-sectional view of an electric auxiliary drive unit according to a second modification. 7 is a vertical cross-sectional view of an electric auxiliary drive unit according to a third modification. FIG. 8 is a cross-sectional view of the electric auxiliary drive unit viewed from the position B-B in FIG. 7 . 9 is a longitudinal cross-sectional view of an electric auxiliary drive unit according to a fourth modification. 10 is a vertical cross-sectional view of an electric auxiliary drive unit according to a fifth modification. 11 is a transverse cross-sectional view of an electric auxiliary drive unit according to a sixth modification. 12 is a side view of an electric auxiliary drive unit of a seventh modification.

1: Electric auxiliary drive unit

9: Central axis

10: Crankshaft

20: Shell

21: Motor housing

22: reducer housing

23: End cap

24: Bolts

27: Partition

28: Oil seals

30: Torque sensor

40: Motor

41: Stator

411: stator core

412: Coil

42: circuit substrate

43: Rotor

431: Rotor yoke

432: Magnet

50: reducer

51: Intermediate rotating body

511: Planetary shaft

52: Planetary gear/flexible external gear/planet roller

521: First external tooth/first inclined surface

522: Second external tooth/second inclined surface

53: Fixed internal gear/internal gear/non-rotating ring

531: First internal tooth/internal tooth/third inclined surface

532:Key

54: Movable internal gear/rotatable ring

541: Second inner tooth/fourth inclined surface

55: Output rotating body

551: Flange

552: Bushing

56: Bolts

57: Bolts

60: One-way clutch

81: The first bearing

82: Second bearing

83: The third bearing

84: Fourth bearing

Claims (23)

An electric auxiliary drive unit, which utilizes the driving force of an electric motor to assist the rotation realized by manpower, including: a crankshaft, which is rotated around the central axis by manpower; a housing that is radially supported on the crankshaft via a first bearing; and an electric motor and a reducer, the electric motor and the reducer are arranged in the space between the crankshaft and the casing, The electric motor has: a stator, the stator is fixed to the housing; a circuit substrate that supplies a drive current to the stator according to a load applied to the crankshaft; and a rotor that rotates around the central axis by a rotating magnetic field generated from the stator by the drive current, It is characterized in that, The speed reducer decelerates the rotation of the rotor and outputs it to the crankshaft, The rotor is radially supported on the crankshaft via a second bearing. The electric auxiliary drive unit of claim 1, wherein, The reducer has: an intermediate rotating body, the intermediate rotating body is fixed to the rotor; a fixing member fixed to the housing; and an output rotating body, the output rotating body is centered on the central axis and rotates at a decelerated rotational speed, Along with the rotation of the intermediate rotating body, the output rotating body rotates with respect to the fixed member at a rotational speed lower than that of the intermediate rotating body. The electric auxiliary drive unit of claim 2, wherein, The fixed member is an annular fixed internal tooth gear centered on the central axis, The speed reducer has a movable internal tooth gear, and the movable internal tooth gear is in the shape of an annular shape centered on the central axis, and rotates together with the output rotating body, The number of teeth of the fixed internal gear is different from the number of teeth of the movable internal gear, The speed reducer further includes a planetary gear that meshes with the fixed internal gear and the movable internal gear and revolves around the central axis with rotation of the intermediate rotating body. The electric auxiliary drive unit of claim 2, wherein, The fixed member is an annular non-rotating ring centered on the central axis, The speed reducer has a rotatable ring, the rotatable ring is annular with the center axis as the center, and rotates together with the output rotating body, the inner diameter of the rotatable ring is different from the inner diameter of the non-rotating ring, The speed reducer further includes planetary rollers that are in contact with the non-rotating ring and the rotatable ring and revolve around the central axis as the intermediate rotating body rotates. The electric auxiliary drive unit of claim 4, wherein, In the contact portion between the non-rotating ring and the planetary roller, at least one of the surfaces of the non-rotating ring and the planetary roller is an inclined surface whose diameter decreases as it moves away from the rotatable ring, In the contact portion between the rotatable ring and the planetary roller, at least one of the surfaces of the rotatable ring and the planetary roller is an inclined surface whose diameter decreases as the distance from the non-rotating ring increases. The electric auxiliary drive unit of claim 5, wherein, The speed reducer further has a pressing mechanism that presses the non-rotating ring in the axial direction toward the rotatable ring side. The electric auxiliary drive unit of claim 2, wherein, The fixed member is an annular fixed internal tooth gear centered on the central axis, The speed reducer has a movable internal tooth gear, and the movable internal tooth gear is in the shape of an annular shape centered on the central axis, and rotates together with the output rotating body, The number of teeth of the fixed internal gear is different from the number of teeth of the movable internal gear, The intermediate rotating body includes a non-circular cam whose outer diameter varies depending on the position in the circumferential direction, The speed reducer further includes a ring-shaped externally toothed gear that is pressed by the outer peripheral surface of the cam and is flexibly deformed, and is connected to the fixed internal toothed gear and the movable internal toothed gear in a part of the circumferential direction. Tooth gear meshes. The electric auxiliary drive unit of claim 1, wherein, The reducer has: an intermediate rotating body, the intermediate rotating body is fixed to the rotor and includes a non-circular cam whose outer diameter varies depending on the position in the circumferential direction; an annular internal gear, the internal gear is centered on the central axis; an externally-toothed gear that is pressed by an outer peripheral surface of the cam and is flexibly deformed, and meshes with the internally-toothed gear in a part of the circumferential direction; and an output rotating body, the output rotating body is centered on the central axis and rotates at a decelerated rotational speed, Either one of the internal gear and the external gear is fixed to the housing, The other of the gear with internal teeth and the gear with external teeth rotates around the central axis at a rotational speed lower than that of the intermediate rotary body together with the output rotary body. The electric auxiliary drive unit of claim 8, wherein, the internal gear is fixed to the casing, The external gear has: a cylindrical portion having a plurality of external teeth; and a circular plate portion extending radially inward from an end portion in the axial direction of the cylindrical portion, The output rotary body rotates together with the externally toothed gear. The electric auxiliary drive unit of claim 8, wherein, The external gear has: a cylindrical portion having a plurality of external teeth; and a disk portion that expands radially outward from an end portion in the axial direction of the cylindrical portion, The circular plate portion is fixed to the housing, The output rotary body rotates together with the internally toothed gear. The electric auxiliary drive unit of claim 10, wherein, The internally toothed gear is supported by the housing via a crossed roller bearing. An electric auxiliary drive unit as claimed in any one of claims 2 to 11, It also includes a one-way clutch that transmits only one-way rotation about the central axis between the output rotary body and the crankshaft. The electric auxiliary drive unit of claim 12, wherein, The output rotor has a cylindrical bush that protrudes in the axial direction toward the motor, The one-way clutch is located radially between the bushing and the crankshaft. The electric auxiliary drive unit of any one of claims 1 to 13, wherein, The electric motor is an axial gap electric motor in which the magnets of the stator and the rotor are axially opposed. The electric auxiliary drive unit of any one of claims 1 to 13, wherein, The electric motor is an outer rotor type electric motor in which the magnet of the rotor is located radially outside of the stator. The electric auxiliary drive unit of any one of claims 1 to 13, wherein, The electric motor is an inner rotor type electric motor in which the magnet of the rotor is located radially inward of the stator. The electric auxiliary drive unit of any one of claims 1 to 16, wherein, the crankshaft is rotatably supported relative to the frame, the housing has a rotation stop part in contact with the frame, The rotation of the housing about the center axis is stopped by the contact of the rotation stopper with the frame. The electric auxiliary drive unit of any one of claims 1 to 16, wherein, The housing is supported on the frame, The housing is fixed to the frame. The electric auxiliary drive unit of any one of claims 1 to 18, wherein, The casing is made of resin. An electric auxiliary drive unit as claimed in any one of claims 1 to 19, also includes a torque sensor that detects the torque of the crankshaft and inputs a detection signal to the circuit substrate, The circuit board supplies the drive current to the stator when the torque indicated by the detection signal is equal to or greater than a predetermined threshold value. An electric auxiliary drive unit as claimed in any one of claims 1 to 20, installed on a bicycle with pedals, The crankshaft is rotated by the pedaling force from the pedals. An electric auxiliary drive unit as claimed in claim 21, Also includes a sprocket, the sprocket is engaged with the bicycle chain, The sprocket is fixed to the crankshaft. A bicycle characterized in that, Comprising the electric auxiliary drive unit of any one of claims 1 to 22.

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