CN111372841B

CN111372841B - Drive unit of electric power-assisted bicycle and electric power-assisted bicycle

Info

Publication number: CN111372841B
Application number: CN201880075692.2A
Authority: CN
Inventors: 川上将史
Original assignee: Panasonic Intellectual Property Management Co Ltd
Current assignee: Panasonic Intellectual Property Management Co Ltd
Priority date: 2017-11-24
Filing date: 2018-11-21
Publication date: 2022-09-20
Anticipated expiration: 2038-11-21
Also published as: JP2024028573A; JP7454790B2; JPWO2019103022A1; DE112018006005T5; WO2019103022A1; CN111372841A

Abstract

The invention provides a small-sized driving unit capable of restraining the area around a crankshaft to the minimum and an electric power-assisted bicycle with the driving unit. A drive unit (20) provided with an electric motor is arranged at a middle position between a front wheel and a rear wheel, a crankshaft (7a) and the electric motor (21) are arranged in the drive unit (20) at different axes, a substrate (24) is arranged in the drive unit (20), and the substrate (24) is arranged in a manner of having a part overlapped with a stator (21c) of the electric motor (21) when the drive unit (20) is observed along the side surface of the crankshaft (7 a).

Description

Drive unit of electric power-assisted bicycle and electric power-assisted bicycle

Technical Field

The present invention relates to a drive unit mounted on an electric power-assisted bicycle that can travel by applying an assist drive force generated by an electric motor to a manual drive force of a pedal force from a pedal, and to the electric power-assisted bicycle.

Background

There is known an electric power-assisted bicycle (also referred to as an electric bicycle) which has a battery as a power source and a drive unit including an electric motor supplied with power from the battery, and which is capable of easily traveling even on an uphill slope or the like by applying an auxiliary drive force (assist force) of the drive unit to a manual drive force generated by a pedaling force applied to pedals.

In this electric power-assisted bicycle, a drive unit incorporating a motor and the like is disposed at a portion where a crankshaft is provided. In the electric power-assisted bicycle having such an arrangement structure, the drive unit having a large weight is arranged at a lower position in the center in the front-rear direction of the electric power-assisted bicycle (i.e., in the middle between the front wheel and the rear wheel). Therefore, the electric bicycle having this arrangement structure has advantages such as easy lifting of the front wheel and the rear wheel, easy passing even if there is a step on the traveling road, good handling of the vehicle body, and good traveling stability, compared to an electric bicycle in which the electric motor is built in the hub of the front wheel or the hub of the rear wheel.

The drive unit incorporates a board (also referred to as a main board or a drive board) on which various electronic components for driving or controlling the motor are mounted. This substrate has a large area because a large electronic component such as an FET or many electronic components are mounted thereon. The substrate is also disposed around the crankshaft in a side view (in a view from the crankshaft center) as shown in, for example, japanese patent application laid-open No. 2016-203735.

However, in recent years, in an electric power-assisted bicycle, the distance from the crankshaft to the rear wheel or the front wheel does not change much from that of a normal bicycle, and it is sometimes desired that the electric power-assisted bicycle can function well as a bicycle. However, when the drive unit in which the base plate is disposed around the crankshaft is employed, there are problems in that a larger area is required around the crankshaft as the base plate becomes larger, the size of the drive unit becomes larger, and the distance from the crankshaft to the axle of the rear wheel becomes longer even when the arrangement of the drive unit is studied.

Disclosure of Invention

The present invention has been made to solve the above problems, and an object of the present invention is to provide a drive unit for an electric power-assisted bicycle, which can be reduced in size by minimizing the area around a crankshaft, and which can function well as a bicycle, and an electric power-assisted bicycle provided with the drive unit.

In order to solve the above problem, a drive unit for an electric power-assisted bicycle according to the present invention is an electric power-assisted bicycle that is attached to the electric power-assisted bicycle and capable of traveling by applying an auxiliary drive force of an electric motor to a manual drive force from a pedal force, and includes the electric motor, the drive unit including: an attachment portion attached to a middle portion between a front wheel and a rear wheel of the electric power-assisted bicycle; a crankshaft insertion region through which a crankshaft to which a manual driving force from the pedal is transmitted is inserted; and a driving force output wheel for outputting the driving force, wherein the crankshaft and the motor are arranged at different axial centers, and a substrate having a portion overlapping with a stator of the motor when viewed along a side surface of the crankshaft is arranged inside the driving unit. In addition, a plurality of substrates may be provided inside the drive unit, and in this case, the substrate having a portion overlapping with the stator of the motor may be a substrate having a largest area among the plurality of substrates.

According to this configuration, since the substrate is disposed so as to have a portion overlapping with the stator of the motor when viewed from the side, a substrate having a sufficiently large area can be used as the substrate. In addition, even when the substrate (additional substrate or part of the substrate) is disposed around the crankshaft, the area of the substrate around the crankshaft can be reduced, and therefore, the distance from the crankshaft to the axle of the rear wheel can be made closer to that of a normal bicycle by studying the disposition of the drive unit and the like.

Preferably, the substrate is disposed so as to overlap with at least half of an area of a stator of the motor in a side view. In addition, the substrate may be disposed so as to overlap a region where a stator of the motor is disposed to a region around the crankshaft when viewed from the side.

Further, a motor rotation sensor for reading rotation of the motor or a crank rotation sensor for reading rotation of the crank shaft may be mounted on the substrate, whereby the number of parts and the number of mounting steps can be reduced.

Preferably, the electric motor is configured such that rotation of the electric motor is transmitted to the driving force output wheel body that outputs the driving force via the two-stage reduction mechanism, and the reduction ratio, which is a ratio of the rotational speed of the electric motor to the rotational speed of the driving force output wheel body, is 30 to 37. Further, the minimum radius around the crankshaft is preferably 50mm or less.

Further, the present invention provides an electric power-assisted bicycle including a drive unit, wherein a speed reduction mechanism having a plurality of pairs of reduction gears is provided, the speed reduction mechanism including: an intermediate shaft disposed in parallel with the crankshaft; a plurality of counter shaft reduction gears provided to the counter shaft; a crankshaft reduction gear which is rotatably disposed on an outer periphery of the crankshaft and transmits a manual driving force and an assist driving force; and a motor shaft reduction gear provided to the motor shaft and having an intermediate shaft bearing rotatably supporting the intermediate shaft, the intermediate shaft being disposed between the crankshaft and the motor shaft with respect to the front-rear direction, the intermediate shaft being disposed below a straight line connecting the crankshaft and the motor shaft when the motor shaft is disposed forward of the crankshaft, and the intermediate shaft being disposed above the straight line connecting the crankshaft and the motor shaft when the motor shaft is disposed rearward of the crankshaft.

In this case, the crankshaft, the motor shaft, and the intermediate shaft are preferably arranged such that an intersection angle of a line connecting the axis of the crankshaft and the axis of the intermediate shaft with respect to a line connecting the axis of the crankshaft and the axis of the motor shaft is within 30 degrees to 70 degrees in the clockwise direction when viewed from the right side in the traveling direction of the electric power-assisted bicycle.

In this configuration, since a reaction force is generated when the reduction gears mesh with each other and a large reaction force acts on the intermediate shaft, a large-sized bearing capable of supporting a large force is used as at least one of the intermediate shaft bearings rotatably supporting the intermediate shaft, and as a result, the drive unit tends to be easily increased in size (particularly, the drive unit tends to be increased in size in the width direction).

However, according to the above configuration (arrangement of the crankshaft, the motor shaft, and the intermediate shaft), it is possible to minimize reaction forces to the intermediate shaft generated when the reduction gears are engaged with each other while canceling each other. As a result, the intermediate shaft bearing can be downsized (downsized in the width direction and the radial direction), and further, the drive unit can be downsized (for example, the drive unit can be downsized in the width direction and the like).

The present invention also provides a driving power supply device for an electric power-assisted bicycle, including the driving unit and an electric storage device for supplying electric power to the driving unit.

Further, the electric bicycle according to the present invention is characterized by including the drive unit or the drive power supply device of the electric bicycle described in any one of the above.

According to the present invention, by disposing the substrate so as to have a portion overlapping the stator of the motor when viewed from the side, a substrate having a sufficiently large area can be used as the substrate, and the area of the substrate around the crank shaft can be suppressed to be small even when the substrate (an additional substrate or a part of the substrate) is disposed around the crank shaft. Thus, by studying the arrangement of the drive unit, the distance from the crankshaft to the axle of the rear wheel can be made closer to that of a normal bicycle. Further, by disposing the substrate so as to have a portion overlapping the stator of the motor when viewed from the side, a so-called sound insulation effect is obtained in which sound generated by the motor can be blocked by the substrate.

Further, according to the present invention, the rotation of the motor is transmitted to the driving force output wheel body attached to the driving unit via the two-stage speed reduction mechanism, and the reduction ratio, which is the ratio of the rotational speed of the motor to the rotational speed of the driving force output wheel body, is 30 to 37. This makes it possible to make the distance from the crankshaft to the axle of the rear wheel close to that of a normal bicycle (e.g., a so-called sport bicycle).

Further, by setting the minimum radius of the driving unit around the crankshaft (around the crankshaft) to 50mm or less, the distance from the crankshaft to the axle of the rear wheel can be made closer to that of a normal bicycle (for example, a so-called sport bicycle).

Further, according to the present invention, when the intermediate shaft is disposed between the crankshaft and the motor shaft with respect to the front-rear direction and the motor shaft is disposed forward of the crankshaft, the intermediate shaft is disposed below a straight line connecting the crankshaft and the motor shaft, and when the motor shaft is disposed rearward of the crankshaft, the intermediate shaft is disposed above the straight line connecting the crankshaft and the motor shaft, or further, when the drive unit is viewed from the right side surface in the traveling direction, the crankshaft, the motor shaft, and the intermediate shaft are disposed such that the angle of intersection of a line connecting the axis of the crankshaft and the axis of the intermediate shaft with respect to a line connecting the axis of the crankshaft and the axis of the motor shaft is within 30 degrees to 70 degrees in the clockwise rotation direction. With this configuration, it is possible to minimize reaction forces to the intermediate shaft generated when the reduction gears mesh with each other while suppressing the reaction forces to the intermediate shaft from canceling each other, and it is possible to reduce the size of the intermediate shaft bearing and thus the drive unit (for example, to reduce the size of the drive unit in the width direction or the like). As a result, the distance between the crank arms can be made close to that of a normal bicycle (for example, a so-called sport bicycle).

Drawings

Fig. 1 is an overall left side view of an electric power-assisted bicycle to which a drive unit according to an embodiment of the present invention is mounted.

Fig. 2 is a plan sectional view of a drive unit of an electric power assisted bicycle according to the same embodiment (first embodiment).

Fig. 3 is a simple right side sectional view of the same drive unit.

Fig. 4 is a plan sectional view of a drive unit according to a first modification of the first embodiment of the present invention.

Fig. 5 is a plan sectional view of a drive unit according to a second modification of the first embodiment of the present invention.

Fig. 6 is a plan sectional view of a drive unit of an electric power assisted bicycle according to a second embodiment of the present invention, in which a high speed clutch is in a non-coupled state.

Fig. 7 is a simple right side sectional view of the same drive unit with the high speed clutch in a connected state.

Fig. 8 is an enlarged plan sectional view of a main portion of an intermediate shaft of the same drive unit and its vicinity, and the high-speed clutch is in a non-connected state.

Fig. 9 is a plan sectional view of the same drive unit, with the high speed clutch in a connected state.

Fig. 10 is an enlarged plan sectional view of a main portion of an intermediate shaft of the common drive unit and its vicinity, and the high-speed clutch is in a connected state.

Fig. 11 is a simple plan view showing a motor shaft, an intermediate shaft, a crankshaft, and reduction gears assembled to these shafts of a drive unit of an electric power-assisted bicycle according to a first embodiment of the present invention.

Fig. 12 is a simple right side cross-sectional view showing a force vector (reaction force) acting on a contact portion of the gear with the driving unit.

Fig. 13 is a simple right side cross-sectional view showing a state in which the force vector (reaction force) acts on the intermediate shaft with the drive unit.

Fig. 14 is a plan sectional view of a drive unit of an electric power assisted bicycle according to a third embodiment of the present invention.

Fig. 15 is a simple right side cross-sectional view showing a force vector (reaction force) acting on a contact portion of the gear with the driving unit.

Fig. 16 is a simple right side cross-sectional view showing a state in which a force vector (reaction force) acts on the intermediate shaft with the drive unit.

Fig. 17 is a right side sectional view of a drive unit according to a modification of the third embodiment of the present invention.

Detailed Description

(first embodiment)

Hereinafter, a drive unit of an electric bicycle according to an embodiment of the present invention and an electric bicycle equipped with the drive unit will be described with reference to the drawings. In the following description, the left-right direction and the front-rear direction refer to directions in a traveling direction in a state where a person rides on the electric power-assisted bicycle 1. The structure of the present invention is not limited to the structure described below.

Fig. 1 shows an electric power-assisted bicycle in which a drive unit according to an embodiment of the present invention is mounted. As shown in fig. 1, the electric power bicycle 1 includes: a metal frame 2 including a head pipe 2a, a front fork 2b, an upper pipe 2c, a lower pipe 2g, a riser pipe 2d, a chain cage 2e, and a rear upper fork 2 f; a front wheel 3 rotatably attached to a lower end of the front fork 2 b; a rear wheel 4 rotatably attached to a rear end of the chain frame 2 e; a handlebar 5 that changes the direction of the front wheel 3; a seat 6 for seating a rider; a crank 7 and a pedal 8 to which a manual driving force is applied, the manual driving force being a pedaling force; an electric motor 21 (see also fig. 2) as a driving source for generating an assist driving force (assist force), and a driving unit (driving unit device) 20 provided with a control unit and the like for controlling various electric components including the electric motor 21; a battery 12 including a secondary battery for supplying driving power to the motor 21; a hand operation portion 18 that is attached to the handlebar 5 or the like, is operable by a rider or the like, and is capable of switching the power supply of the electric power-assisted bicycle 1 and setting a running mode to be changed; a drive sprocket (also referred to as a front sprocket, a crank sprocket, and a front gear) 13 as a drive force output wheel body that is attached so as to rotate integrally with the crankshaft 7a on the same axis, and that outputs a resultant force combining a manual drive force and an assist drive force; a rear sprocket 14 (also referred to as a rear gear) as a rear wheel body attached to a hub (also referred to as a rear hub) 9 of the rear wheel 4; the chain 15 as an endless driving force transmission body is wound in an endless shape or the like in a state of being rotatable over the driving sprocket 13 and the rear sprocket 14. In addition, a driving power supply device (driving unit module) is configured by the driving unit 20 and the battery 12.

The electric power-assisted bicycle 1 can travel by adding an assist driving force generated by the electric motor 21 to a manual driving force of a pedaling force from the pedals 8, and a resultant force of the assist driving force applied to the manual driving force is transmitted from the driving sprocket 13 to the rear wheel 4 via the chain 15, the rear sprocket 14, and the like.

The battery 12 is an example of an electric storage device, and preferably a secondary battery, but the electric storage device may be a capacitor or the like. The crank 7 is composed of crank arms 7b provided on the left and right sides, respectively, and a crankshaft 7a connecting the crank arms 7b to each other, and a pedal 8 is rotatably attached to an end of the crank arm 7 b.

As shown in fig. 1, in the electric bicycle 1, the driving unit 20 is disposed at an intermediate position between the front wheel 3 and the rear wheel 4, more specifically, at a portion through which the crankshaft 7a penetrates. By adopting such an arrangement, the drive unit 20 having a large weight is arranged at the center in the front-rear direction of the electric power-assisted bicycle 1. This makes it easy to lift the front wheel 3 and the rear wheel 4, and to get over easily even if there is a step on the traveling road, and the electric power-assisted bicycle 1 has good handling of the body (the frame 2, etc.) and good traveling stability.

As shown in fig. 2, the drive unit 20 includes a unit case 22 including first to third cases 22a to 22c, for example, an outer shell, and the crankshaft 7a penetrates the drive unit 20 (in the present embodiment, the crankshaft insertion region 16 provided at the rear of the drive unit 20) in the left-right direction. The unit case 22 is integrally formed with a mounting portion 22d for mounting the drive unit 20 to an intermediate portion between the front wheel and the rear wheel in the electric power-assisted bicycle. Further, on the outer periphery of the crankshaft 7a, there are disposed: a substantially cylindrical human power transmission body 28 that transmits the human power from the crankshaft 7a, an interlocking cylinder 23 that transmits the human power from the human power transmission body 28, and a resultant power transmission body 29 that transmits the resultant force of the human power and the assist power from the electric motor 21 to the drive sprocket 13 by transmitting the human power from the interlocking cylinder 23 via a one-way clutch (one-way clutch for interrupting the assist power) 30 or the like.

In addition, a reduction mechanism 25 that reduces the rotation speed of the motor 21 and transmits the rotation speed to the resultant force transmission body 29 side (in this embodiment, the intermediate shaft 40) and the motor 21 that is an assist driving force (assist) driving source are arranged in the unit case 22 of the drive unit 20, and a board (also referred to as a driving board or a main board) 24 on which electronic components for performing various kinds of electric control are provided is also arranged. The control unit is constituted by a substrate 24 and electronic components (FET (field effect transistor) 24a, a capacitor, a microcomputer, and the like) mounted on the substrate. As shown in fig. 2 and 3, the position of the axial center of the rotating shaft 21a of the motor 21, the axial center of the crankshaft 7a, and the axial center of the intermediate shaft 40 described later are different from each other. In this embodiment, the rotary shaft 21a of the motor 21, the intermediate shaft 40, and the crankshaft 7a are arranged in this order from the front, and the intermediate shaft 40 is arranged below a straight line connecting the crankshaft 7a and the motor shaft 21 a. Further, the drive unit 20 (more specifically, the unit case 22 of the drive unit 20) is provided with a portion excluding both end portions of the crankshaft 7a, a human power transmission body 28, an interlocking cylinder 23, a resultant force transmission body 29, a speed reduction mechanism 25, a motor 21, a torque sensor 31, a rotation detection body 11, a rotation detector (rotation sensor) 10, and the like, which will be described later. The manual driving force and the assist driving force are combined in the driving unit 20, and the combined force is configured to be output from the driving sprocket 13 provided outside the driving unit 20 (specifically, outside the unit case 22 of the driving unit 20).

The drive unit 20 will be described in more detail. As shown in fig. 2 and 3, the crankshaft 7a is rotatably disposed by bearings (crank bearings) 26 and 27 in a state of penetrating the rear portion of the drive unit 20 in the left and right directions. Further, a cylindrical human force transmission body 28 is fitted to the outer periphery of the left side portion of the crankshaft 7a via serrations (or spline portions) 7c in a state of rotating integrally with the crankshaft 7 a. Further, serrations (or spline portions) 28b are formed on the inner periphery of the human power transmission body 28 at positions corresponding to the serrations (or spline portions) 7c of the crankshaft 7a, and mesh with the serrations (or spline portions) 7c of the crankshaft 7 a.

A magnetostrictive generation part 31b to which magnetic anisotropy is applied is formed on the outer peripheral surface of the human force transmitting body 28, a coil 31a is disposed on the outer periphery thereof with a certain gap (space) therebetween, and a magnetostrictive torque sensor (human force detection part) 31 is configured by the magnetostrictive generation part 31b and the coil 31 a. Thereby, the man-power driving force from the crankshaft 7a is transmitted to the man-power transmission body 28, and the man-power driving force is detected by the torque sensor 31. In the magnetostrictive torque sensor 31, the magnetostrictive generation part 31b is formed in a spiral shape that forms, for example, +45 degrees and-45 degrees with respect to the axial direction of the human force transmitter 28. Further, since strain is generated in the magnetostrictive generation part 31b on the surface of the human power transmission body 28 when the human power driving force is transmitted to the human power transmission body 28, and an increase part and a decrease part of the magnetic permeability are generated, the magnitude of the torque (human power driving force) can be detected by measuring the inductance difference of the coil 31 a.

The interlocking cylinder 23 is disposed at a position adjacent to the right side of the human power transmission body 28 on the outer periphery of the crankshaft 7a in a rotatable state with respect to the crankshaft 7 a. Further, the serration (or spline) 28a formed on the outer periphery of the right end portion of the manual power transmission body 28 and the serration (or spline) 23a formed on the inner periphery of the left end portion of the interlocking cylinder body 23 are fitted to each other, and the interlocking cylinder body 23 and the manual power transmission body 28 rotate integrally. In this embodiment, the serration (or spline) 23a formed on the inner periphery of the left end portion of the interlocking cylinder 23 is fitted to the serration (or spline) 28a of the human power transmission body 28 from the outside.

In this embodiment, a rotation detector 11 for detecting the rotation state of the interlocking cylinder 23 is attached to the outer periphery of the left side portion of the interlocking cylinder 23. A rotation detector (rotation sensor) 10 as a crank rotation sensor is attached and fixed to the unit case 22 side so as to face the rotation detection body 11 from the outer peripheral side. For example, the optical sensor of the rotation detector 10 having the emitting portion and the light receiving portion is configured to be arranged along the rotation direction of the rotation detection body 11 (not shown), and the rotation detection body 11 has a plurality of teeth portions extending in a comb (comb) tooth shape to the right side at an outer peripheral side portion thereof. When the tooth portion of the rotation detector 11 is provided, the light receiving unit of the rotation detector 10 electrically detects the incident state and the non-incident state of the light by reflecting and receiving the emitted light, and the control unit inputs the detected signal to detect the rotation speed (rotation amount) and the rotation direction of the interlocking cylinder 23. Instead of the optical sensor, a magnetic sensor such as a hall IC may be provided to detect the rotation speed (rotation amount) and rotation direction of the interlocking cylinder 23. Here, since the interlocking cylinder 23 and the manual power transmission body 28 rotate integrally and the manual power transmission body 28 and the crankshaft 7a rotate integrally, the rotational speed (rotational amount) and rotational direction of the crankshaft 7a and the pedals 8 can be detected by detecting the rotational amount and rotational direction of the interlocking cylinder 23.

Further, a resultant force transmitting body 29 is disposed on the outer periphery of the right side portion of the interlocking cylinder 23 via a one-way clutch (one-way clutch for power-assisted driving force cutoff) 30. When the pedal 8 is stepped on and advanced, the manual driving force transmitted to the interlocking cylinder 23 is transmitted to the resultant force transmitting body 29 via the one-way clutch 30.

The motor 21 rotatably supports a rotating shaft 21a and a rotor 21b thereof by

motor shaft bearings

32 and 33. The rotary shaft 21a of the motor 21 projects rightward, and a motor shaft reduction gear 39, which will be described later, is formed on the outer periphery of the projecting portion.

The speed reduction mechanism 25 includes an intermediate shaft 40 disposed parallel to the crankshaft 7a, two pairs of reduction gears 36 to 39 including a large-diameter reduction gear (first reduction gear: crankshaft side reduction gear) 36 formed in the left portion of the resultant force transmission body 29, and the like, and constitutes a two-stage speed reduction mechanism. The speed reduction mechanism 25 combines the manual driving force transmitted through the crankshaft 7a and the assist driving force transmitted from the motor 21, and transmits a resultant force obtained by combining the manual driving force and the assist driving force to the resultant force transmission member 29.

The intermediate shaft 40 extends to the left and right in the central portion in the front-rear direction of the drive unit 20, and is disposed in a state of being supported rotatably by bearings (intermediate shaft bearings) 34 and 35 in a posture parallel to the crankshaft 7 a. A large-diameter second intermediate shaft reduction gear 37, a small-diameter third intermediate shaft reduction gear 38, and a one-way clutch 42 for disconnecting the manual driving force are attached to the intermediate shaft 40.

The manual driving force cutoff one-way clutch 42 is disposed between the outer periphery of the counter shaft 40 and the inner periphery of the second counter shaft reduction gear 37, and cuts off the manual driving force from the pedal 8. That is, when the motor 21 is not driven and the assist driving force is not generated, the one-way clutch 42 is configured such that the manual driving force from the pedal 8 is cut off by the one-way clutch 42 for cutting off the manual driving force, and it is not necessary to rotate the rotor 21b of the motor 21. On the other hand, when the electric motor 21 is driven and rotated, the counter shaft 40 and the second counter shaft reduction gear 37 are connected via the one-way clutch 42, and the second and third counter shaft reduction gears 37 and 38 rotate integrally with the counter shaft 40.

Since the small-diameter motor shaft reduction gear 39 formed on the rotary shaft 21a of the motor 21 meshes with the large-diameter second intermediate shaft reduction gear 37, when the motor 21 rotates and outputs the assist driving force, the rotation of the motor 21 is reduced, and the torque of the assist driving force from the motor 21 is amplified and transmitted to the intermediate shaft 40 side. Further, since the small-diameter third counter reduction gear 38 meshes with the large-diameter first reduction gear 36 integrally formed with the resultant force transmission body 29, the torque of the assist driving force transmitted to the counter shaft 40 is further amplified and transmitted to the first reduction gear 36. In the resultant force transmission body 29 integrally formed with the first reduction gear 36, the manual driving force is synthesized with the assist driving force from the motor 21 and is output from the drive sprocket 13 as the driving force output wheel body. Here, the reduction ratio, which is the ratio of the rotation speed of the motor 21 to the rotation speed of the drive sprocket 13, is 30 to 37(30 or more and 37 or less). The minimum radius of the drive unit 20 around the crankshaft 7a (around the crankshaft) is set to 50mm or less.

In this embodiment, only one large-area substrate 24 is provided as a substrate in the unit case 22 of the drive unit 20. The substrate 24 is disposed so as to have a portion overlapping with a stator 21c of the motor 21 (more specifically, a region of the stator of the motor 21 where the stator core is provided) as shown in fig. 3 when the drive unit 20 is viewed along the side surface of the crankshaft 7a (when viewed along the axial center direction side surface of the crankshaft 7 a). In this embodiment, the substrate 24 is disposed so that at least half of the area of the stator 21c of the motor 21 overlaps. In this embodiment, the substrate 24 is disposed so as to overlap a region of the motor 21 where the stator 21c is disposed to a region around the crankshaft 7 a.

In this embodiment, as shown in fig. 3, the substrate 24 is also provided in a region overlapping the rotor 21b of the motor 21 when viewed from the side. The substrate 24 is disposed so that more than half of the area of the rotor 21b of the motor 21 overlaps. That is, in this embodiment, as shown in fig. 3, the substrate 24 is also provided in a region overlapping the motor 21 (the entire motor) in a side view, and the substrate 24 is disposed so that an area of half or more of the motor 21 overlaps.

In this embodiment, as shown in fig. 3, the substrate 24 is also provided in a region where the first reduction gear 36 and the stator 21c of the motor 21 do not overlap each other when viewed from the side. As shown in fig. 2, the substrate 24 is disposed between the motor 21 and the first reduction gear 36, the resultant force transmission member 29, and the interlocking cylinder 23 in a plan view (or a front view). In addition, when viewed from the front (when viewed in the front-rear direction), the substrate 24 is provided in a region overlapping the human force transmitters 28 as schematically shown in fig. 2. In this embodiment, when viewed from the side, the substrate 24 is provided in a region not overlapping the second reduction gear 37 as shown in fig. 3. In addition, in a front view (a view along the front-rear direction), as schematically shown in fig. 2, the base plate 24 is provided in a region not overlapping with the second reduction gear 37. However, the present invention is not limited to this case, and may be provided so that a part of the second reduction gear 37 overlaps the substrate 24 when viewed from the side.

In this embodiment, a rotation detector (rotation sensor) 10 (more specifically, a leg portion for connection of the rotation detector (rotation sensor) 10) as a crank rotation sensor for reading the rotation of the crankshaft is attached to the base plate 24. In this embodiment, as shown in fig. 2, the substrate 24 is provided between the rotation detecting body 11 or the rotation detector (rotation sensor) 10 and a bearing 26 (a bearing 26 supported from the side opposite to the side of the crankshaft 7a on which the drive sprocket 13 is provided) or a torque sensor 31 that supports the crankshaft 7a and the like in a plan view.

In this embodiment, a plurality of magnets are arranged in a circumferential direction so that the magnetic poles of adjacent magnets are different from each other in the rotor 21b of the motor 21, but a substantially cylindrical magnetism applying member 21d having the same magnetic pole as the magnetic pole is arranged. The outer peripheral portion of the magnetism applying member 21d is formed to protrude rightward, and a motor rotation sensor 43 for reading the rotation of the motor 21 is disposed so as to face the end portion 21da of the protruding magnetism applying member 21 d. The motor rotation sensor 43 is attached to the substrate 24.

The magnetism applying member 21d may apply magnetism only to the end 21da thereof in the same manner as the arrangement of the rotor 21b of the motor 21. In this embodiment, the magnetism imparting member 21d also serves as a partition member for partitioning a region (speed reducing mechanism arrangement region) in which the speed reducing mechanism 25 having the plurality of speed reducing gears 36 to 39 and the like is arranged from a region (motor arrangement region) in which the motor 21 is arranged. Further, it is desirable not to cause grease or the like that reduces friction between the reduction gears 36 to 39 to enter the motor 21 side, but this is not the only case. In fig. 2, 21ca denotes a connection line for supplying current to the coil of the stator 21 c.

In the above configuration, if the pedal 8 is depressed during forward travel, a manual driving force based on a depression force applied to the pedal 8 is transmitted from the crankshaft 7a to the manual power transmission body 28, the interlocking cylinder 23, and the resultant force body 29, and the manual driving force is detected by the torque sensor 31 provided in the manual power transmission body 28. The auxiliary driving force corresponding to the manual driving force is transmitted to the resultant force transmission body 29 via the speed reduction gear 36 of the speed reduction mechanism 25, and the resultant force combined in the resultant force transmission body 29 is transmitted from the drive sprocket 13 to the rear wheel 4 via the chain 15. Thus, the vehicle can easily travel even on an uphill or the like by applying the assist driving force (assist force) of the electric motor 21 corresponding to the manual driving force.

Further, according to the above configuration, since the substrate 24 is disposed to have a portion overlapping the stator 21c of the motor 21 in a side view, a substrate having a sufficiently large area can be used as the substrate 24. Further, as in this embodiment, even when the base plate 24 is disposed around the crankshaft 7a, the area of the region of the base plate 24 around the crankshaft 7a can be kept small, and therefore, by studying the disposition of the drive unit 21 (for example, disposing the motor 21 on the front side of the crankshaft 7a) or the like, the distance from the crankshaft 7a to the axle of the rear wheel 4 can be made closer to that of a normal bicycle (for example, a so-called sport bicycle).

As described above, the substrate 24 is disposed so that the area passing through half or more of the stator 21c of the motor 21 overlaps when viewed from the side, and thus the area of the region around the crankshaft 7a in the substrate 24 can be minimized. Therefore, the distance from the crankshaft 7a to the axle of the rear wheel 4 of the electric bicycle 1 can be made closer to that of a normal bicycle (for example, a so-called sport bicycle). Further, by disposing the substrate 24 so as to have a portion overlapping the stator 21c of the motor 21 when viewed from the side, the sound generated in the motor 21 can be blocked by the substrate 24. That is, as described above, the substrate 24 is disposed so as to overlap with at least half of the area of the stator 21c of the motor 21, and the sound insulation effect can be further improved.

In the above embodiment, the motor rotation sensor 43 that reads the rotation of the motor 21 and the rotation detector 10 that is a crank rotation sensor that reads the rotation of the crank shaft 7a are mounted on the substrate 24. With this configuration, the number of components of the substrate 24 itself in the drive unit 20 can be reduced to only one, and the number of components and the trouble of mounting the substrate can be reduced. Further, in the present invention, as schematically shown in fig. 2, since the substrate 24 is provided between the motor 21 and the first reduction gear 36 or the resultant force transmission body 29 and the interlocking cylinder 23 in a plan view (or a front view), there is an advantage that the motor rotation sensor 43 and the rotation detector 10 as the crank rotation sensor can be easily attached to the substrate 24. Further, as shown in fig. 2, since the substrate 24 is provided so as to overlap the rotor 21b of the motor 21 or the magnetism applying member 21d in a side view, there is an advantage that the motor rotation sensor 43 can be easily attached to the substrate 24.

However, not limited to this, as shown in fig. 4, the crank rotation sensor assist substrate 24A on which the rotation detector 10 as the crank rotation sensor is mounted may be provided separately from the substrate (main substrate) 24, and the crank rotation sensor assist substrate 24A may be connected to the substrate (main substrate) 24 (first modification of the first embodiment). As shown in fig. 5, the motor rotation detection assist substrate 24B on which the motor rotation sensor 43 is mounted may be provided separately from the substrate (main substrate) 24, and the motor rotation detection assist substrate 24B may be connected to the substrate (main substrate) 24 (second modification of the first embodiment). In this embodiment, as shown in fig. 4 and 5, the substrate (main substrate) 24 is provided between the rotation detecting body 11 or the rotation detector (rotation sensor) 10 and the bearing 26 (the bearing 26 on the side opposite to the side of the crankshaft 7a on which the drive sprocket 13 is provided) supporting the crankshaft 7a or the like or the torque sensor 31 in plan view. In these cases, the base plate (main base plate) 24 is preferably larger (larger in area) than the crank rotation sensor booster base plate 24A or the motor rotation detection booster base plate 24B.

The rotation of the motor 21 is transmitted to the drive sprocket 13 as a drive force output wheel body via the two-stage reduction mechanism 25, and the reduction ratio, which is the ratio of the rotation speed of the motor 21 to the rotation speed of the drive sprocket 13, is 30 to 37. Thus, a gear having a small diameter can be used as the first reduction gear 36 coaxial with the crankshaft 7 a. As a result, the diameter (radius and diameter) around the crankshaft 7a in the drive unit 20 can be reduced, and the distance from the crankshaft 7a to the axle of the rear wheel 4 can be made closer to that of a normal bicycle (for example, a so-called sport bicycle) by studying the arrangement of the drive unit 21 (for example, arranging the motor 21 on the front side of the crankshaft 7 a).

Further, by setting the minimum radius of the driving unit 20 around the crankshaft 7a (around the crankshaft) to 50mm or less, the distance from the crankshaft 7a to the axle of the rear wheel 4 can be made closer to that of a normal bicycle (for example, a so-called sport bicycle). Further, by setting the minimum radius of the driving unit 20 around the crankshaft 7a (around the crankshaft) to 45mm or less, the distance from the crankshaft 7a to the axle of the rear wheel 4 can be made further closer to that of a normal bicycle (e.g., a so-called sport bicycle).

(second embodiment)

In the above embodiment, the case where the reduction ratio of the reduction mechanism 25 is constant has been described, but the present invention is not limited thereto, and the reduction mechanism 25A having a gear shift function capable of selectively switching a plurality of reduction ratios (in the present embodiment, two gear shift stages) may be provided in the drive unit 20.

As shown in fig. 6 to 10, the speed reduction mechanism 25A provided in the drive unit 20 of this embodiment has a plurality of selectable gear shift stages (two-stage gear shift stages of a low speed stage and a high speed stage in this embodiment) having different gear ratios on the outer peripheral side and the right side of the interlocking cylinder 23 via a one-way clutch (one-way clutch for power-assist drive-force cutoff) 30, and transmits drive force to the resultant force transmission member 29.

The speed reduction mechanism 25A includes: a rotation transmission tube 49 rotatably disposed on the outer periphery of the crankshaft 7a, and configured to transmit the rotation of the interlocking tube body 23 via a one-way clutch (one-way clutch for assisting driving force cutoff) 30; a low speed stage transmission gear (also referred to as a crankshaft side low speed stage transmission gear) 36A integrally formed to extend radially outward from a right cylindrical portion of the rotation transmission cylinder 49; a low clutch 51 disposed between the rotation transmission cylinder 49 and the resultant force transmission member 29 and capable of transmitting the driving force of the crankshaft side low speed transmission gear 36A to the resultant force transmission member 29; a high-speed-stage transmission gear (also referred to as a crankshaft-side high-speed-stage transmission gear) 36B rotatably disposed on the outer periphery of the resultant force transmission member 29; a low-speed stage speed change gear (also referred to as a counter shaft-side low-speed stage speed change gear) 38A that is formed integrally with the counter shaft 40 and meshes with the crankshaft-side low-speed stage speed change gear 36A; an intermediate shaft tooth portion 40a formed integrally with the intermediate shaft 40 and meshing with a tooth portion (or a serration portion or a spline portion) 55b formed on an inner peripheral side of a high-speed clutch 55 described later; a high-speed clutch 55 provided on the outer periphery of the intermediate shaft tooth portion 40a of the intermediate shaft 40 and in the right side region thereof and capable of transmitting the resultant force from the intermediate shaft 40 to the crankshaft-side high-speed transmission gear 36B and the resultant force transmission member 29; a high-speed-stage transmission gear portion (an intermediate-shaft-side high-speed-stage transmission gear portion, i.e., a so-called engagement pawl portion of the high-speed clutch 55) 38B configured by an engagement pawl that is freely retractable from the high-speed clutch 55 (specifically, a main body portion 55a of the high-speed clutch 55) to the outer peripheral side and is freely engageable with and disengageable from the crankshaft-side high-speed-stage transmission gear 36B (see fig. 9 and 10); a shift speed switching member 61 that is freely engageable with and disengageable from a right portion of the intermediate shaft-side high-speed shift tooth portion 38B from an outer peripheral side and moves in accordance with a selected shift speed; and a shift movement arm 62 or the like that engages with the gear shift stage switching body 61 and moves the gear shift stage switching body 61 in the crankshaft direction.

When the pedal 8 advances, the manual driving force transmitted to the interlocking cylinder 23 is transmitted to the rotation transmission cylinder 49. In this embodiment, the high-speed clutch 55 is disposed on the outer peripheral side of the intermediate shaft 40 so as to be movable in the same axial direction as the axial center of the intermediate shaft 40.

Here, the diameter of the crankshaft side low speed stage speed gear 36A is larger than that of the crankshaft side high speed stage speed gear 36B, and the diameter of the intermediate shaft side low speed stage speed gear 38A is smaller than that of the intermediate shaft side high speed stage speed gear portion 38B. Accordingly, the rotational force of the intermediate shaft 40 is transmitted to the crankshaft side low speed change gear 36B and the rotation transmission cylinder 49 at a low speed rotation, and is transmitted to the crankshaft side high speed change gear 36B at a high speed rotation.

The shift movement arm 62 is preferably driven by an electric transmission 51 (shown in fig. 7) provided inside the drive unit 20 (or outside the drive unit), and for example, a switch for switching the gear position is preferably provided in the manual operation portion 18, so that the gear position can be switched. However, the present invention is not limited to this, and the shift movement arm (shift portion that moves via a wire or the like) 62 may be provided near the handlebar.

When the low speed stage is selected, as shown in fig. 6 and 8, the shift speed switching member 61 is moved to the left by the shift movement arm 62, and the intermediate shaft side high speed stage transmission gear portion 38B formed of the engagement claws of the high speed stage clutch 55, which are freely retractable, is pushed down and separated from the crankshaft side high speed stage transmission gear 36B. Therefore, the manual driving force transmitted from the interlocking cylinder 23 side through the one-way clutch (one-way clutch for cutting off the assist driving force) 30 and the assist driving force transmitted from the motor side through the intermediate shaft 40 or the intermediate shaft side low speed gear 38A are transmitted to the rotation transmission tube 49 in a low rotation state and combined, and the rotational driving force (combined force) is output from the drive sprocket 13 through the low speed clutch 51 and the combined force transmission body 29.

When the high speed stage is selected, as shown in fig. 9, 10, etc., the shift speed switching member 61 is moved to the right by the shift movement arm 62, and a claw portion engageable with the crankshaft side high speed transmission gear 36B of the high speed clutch 55 (specifically, a tooth portion of the crankshaft side high speed transmission gear 36B) can stand up, and the rotation of the crankshaft side high speed transmission gear 36B can be transmitted to the resultant force transmitting member 29. Therefore, the manual driving force transmitted from the interlocking cylinder 23 side through the one-way clutch (one-way clutch for cutting off the assist driving force) 30 is transmitted to the counter shaft 40 through the crankshaft side low speed ratio speed change gear 36A and the counter shaft side low speed ratio speed change gear 38A, and the assist driving force is combined to become a resultant force. The resultant force is transmitted to the resultant force transmitting body 29 via the intermediate shaft-side high-speed change gear 38B and the crankshaft-side high-speed change gear 36B and is output from the drive sprocket 13 via the high-speed clutch 55 in a state of high-speed rotation. At this time, the resultant force transmission member 29 rotates at a higher speed than the rotation transmission cylinder 49, and therefore, the low clutch 51 idles.

Thus, by using this drive unit 20, the shift stages can also be switched within the drive unit 20. In this embodiment, the same operational effects can be obtained by disposing the substrate 24 and the like as in the above-described embodiment. Further, by configuring the reduction ratio, which is the ratio of the rotation speed of the motor 21 to the rotation speed of the drive sprocket 13 at the low speed stage, to be 30 to 37 and the reduction ratio at the high speed stage to be the following, gears having a small diameter can be used as the crankshaft side low speed stage transmission gear 36A (and the crankshaft side high speed stage transmission gear 36B) coaxial with the crankshaft 7a, and the same operational effects can be obtained.

In the above embodiment, the case where the high speed clutch 55 is provided on the outer periphery of the intermediate shaft 40 has been described, but the present invention is not limited thereto, and may be provided in the outer peripheral region of the crankshaft 7 a. Further, similarly to the above-described embodiment, the crank rotation sensor assist base plate 24A on which the rotation detector 10 as the crank rotation sensor is mounted may be provided separately from the base plate (main base plate) 24, and the crank rotation sensor assist plate 24A may be connected to the base plate (main base plate) 24. Further, the motor rotation detection assist substrate 24B on which the motor rotation sensor 43 is mounted may be provided separately from the substrate (main substrate) 24, and the motor rotation detection assist substrate 24B may be connected to the substrate (main substrate) 24.

In the above-described embodiments (first and second embodiments), the motor shaft (the rotary shaft 21a of the motor 21) is disposed forward of the crankshaft 7a, and the intermediate shaft 40 is disposed downward of a straight line connecting the crankshaft 7a and the motor shaft 21 a. As shown in fig. 11, the second and third counter reduction gears 37 and 38 attached to the counter shaft 40, the motor shaft reduction gear 39 attached to the motor shaft 21a, and the first reduction gear (crankshaft-side reduction gear) 36 disposed on the outer periphery of the crankshaft 7a are each a helical gear to reduce noise. Fig. 11 corresponds to the first embodiment. When the motor 21 is driven and the assist driving force is output, the motor shaft 21a and the motor shaft reduction gear 39 rotate in the clockwise direction (clockwise direction) in a state seen from the right side surface, the second intermediate shaft reduction gear 37, the intermediate shaft 40, and the third intermediate shaft reduction gear 38 that mesh with the motor shaft reduction gear 39 rotate in the counterclockwise direction (counterclockwise direction) in a state seen from the right side surface, and the first crankshaft side reduction gear 36 that meshes with the third intermediate shaft reduction gear 38 rotate in the clockwise direction (clockwise direction) in a state seen from the right side surface.

In this configuration, as shown in fig. 12, when the reduction gears 36 to 39 of the reduction mechanism 25 are meshed with each other, force vectors (reaction forces) V1 to P6 are generated and act on the intermediate shaft 40 as shown in fig. 13. Fig. 12 shows a force vector (reaction force) acting on the contact portion of the gear (force vector (reaction force) ultimately relating to the intermediate shaft 40), and fig. 13 shows a state in which the force vector (reaction force) acts on the intermediate shaft 40 (a state in which the force vector is concentrated on the axial center of the intermediate shaft 40).

In fig. 12 and 13, V1 is a coupling force vector to the counter shaft bearing 35 generated by the engagement of the motor shaft reduction gear 39 and the second counter shaft reduction gear 37, V2 is a separating force vector to the counter shaft bearing 35 generated by the engagement of the motor shaft reduction gear 39 and the second counter shaft reduction gear 37, and V3 is a load vector of a thrust force to the counter shaft bearing 35 generated by the engagement of the motor shaft reduction gear 39 and the second counter shaft reduction gear 37. V4 is a coupling force vector to the counter bearing 35 generated by the engagement of the first reduction gear (crankshaft-side reduction gear) 36 and the third counter reduction gear 38, V5 is a separating force vector to the counter bearing 35 generated by the engagement of the first reduction gear (crankshaft-side reduction gear) 36 and the third counter reduction gear 38, V6 is a load vector of a thrust force to the counter bearing 35 generated by the engagement of the first reduction gear (crankshaft-side reduction gear) 36 and the third counter reduction gear 38, and V7 is a reaction force (resultant force) vector acting on (merging) the counter shaft 40.

According to the above arrangement, the force vectors V1 to P6 generated when the reduction gears 36 to 39 mesh with each other are less cancelled out by each other toward the counter shaft 40, and therefore, a large force vector V7 acts on the counter shaft 40 in a state where these force vectors V1 to P6 are combined. Therefore, the

counter bearings

34 and 35 that rotatably support the counter shaft 40, particularly the counter bearing 35 on the right side closer to the third counter reduction gear 38 that meshes with the first crankshaft reduction gear 36 that transmits the resultant force, receive a large reaction force, and therefore a large gear that can receive a large force is used, which results in an increase in the size of the drive unit 20 (particularly, in the present embodiment, the size in the width direction of the portion of the drive unit 20 where the counter shaft 40 is disposed is increased).

As described above, when the drive unit 20 is increased in size and the width-directional dimension of the drive unit 20 is increased, the distance L1 (see fig. 2) between the left and right crank arms 7b is significantly increased as compared with a conventional bicycle (e.g., a so-called sport bicycle), and therefore, it is difficult to access the function as a conventional bicycle (e.g., a so-called sport bicycle).

To cope with such a problem, in the drive unit 20 of the electric power-assisted bicycle according to the third embodiment of the present invention shown in fig. 14 to 16, the rotary shaft 21a of the motor 21, the intermediate shaft 40, and the crankshaft 7a are arranged in this order from the front (the arrangement is the same as in the above-described embodiment), but unlike the above-described embodiment, the intermediate shaft 40 is arranged above the straight line connecting the crankshaft 7a and the motor shaft 21 a. In this case, in a state where the drive unit 20 is oriented in the traveling direction and viewed from the right side, as shown in fig. 15, the crankshaft 7a, the motor shaft 21a, and the intermediate shaft 40 are arranged such that an angle α at which a line connecting the axis of the crankshaft 7a and the axis of the intermediate shaft 40 intersects with a line a connecting the axis of the crankshaft 7a and the axis of the motor shaft 21a is within 30 degrees to 70 degrees in the clockwise direction of rotation.

The drive unit 20 of the electric power-assisted bicycle according to the third embodiment is different from the drive unit 20 according to the first embodiment mainly in the arrangement of the intermediate shaft 40, the crankshaft 7a, and the motor shaft 21a and the structure (size, etc.) of the bearings associated with the arrangement, and the other structure is the same as the drive unit 20 according to the first embodiment. That is, the second and third counter reduction gears 37 and 38 attached to the counter shaft 40, the motor shaft reduction gear 39 attached to the motor shaft 21a, and the first reduction gear (crankshaft-side reduction gear) 36 disposed on the outer periphery of the crankshaft 7a are all bevel (helical) gears as shown in fig. 11, thereby achieving sound reduction. When the motor 21 is driven and the assist driving force is output, the motor shaft 21a and the motor shaft reduction gear 39 rotate in the clockwise direction (clockwise direction) in a state seen from the right side surface, the second intermediate shaft reduction gear 37, the intermediate shaft 40, and the third intermediate shaft reduction gear 38 that mesh with the motor shaft reduction gear 39 rotate in the counterclockwise direction (counterclockwise direction) in a state seen from the right side surface, and the first crankshaft side reduction gear 36 that meshes with the third intermediate shaft reduction gear 38 rotate in the clockwise direction (clockwise direction) in a state seen from the right side surface.

In this configuration, when the reduction gears 36 to 39 of the reduction mechanism 25 are engaged with each other as shown in fig. 15, force vectors (reaction forces) V11 to P16 are generated and act on the intermediate shaft 40 as shown in fig. 16. Fig. 15 shows a force vector (reaction force) acting on the contact portion of the gear (final force vector (reaction force) related to the intermediate shaft 40), and fig. 16 shows a state where the force vector (reaction force) acts on the intermediate shaft 40 (state where the force vector is concentrated on the axial center of the intermediate shaft 40).

In fig. 15 and 16, V11 is a coupling force vector to the counter bearing 35 generated by the engagement of the motor shaft reduction gear 39 and the second counter reduction gear 37, V12 is a separating force vector to the counter bearing 35 generated by the engagement of the motor shaft reduction gear 39 and the second counter reduction gear 37, and V13 is a load vector of a thrust force to the counter bearing 35 generated by the engagement of the motor shaft reduction gear 39 and the second counter reduction gear 37. V14 is a coupling force vector to the counter bearing 35 generated by the engagement of the first reduction gear (crankshaft-side reduction gear) 36 and the third counter reduction gear 38, V15 is a separating force vector to the counter bearing 35 generated by the engagement of the first reduction gear (crankshaft-side reduction gear) 36 and the third counter reduction gear 38, V16 is a load vector of a thrust force to the counter bearing 35 generated by the engagement of the first reduction gear (crankshaft-side reduction gear) 36 and the third counter reduction gear 38, and P17 is a (combined) reaction force (resultant force) vector acting on the counter shaft 40.

According to the above arrangement, V11 to P16 generated in the intermediate shaft 40 when the reduction gears 36 to 39 mesh with each other cancel each other out, and the reaction force (resultant force) P17 finally acting on the intermediate shaft becomes small, so that a small-sized bearing (a bearing that is small in the width direction or the radial direction) capable of supporting a small load can be used as the intermediate shaft bearing 35, and further, the drive unit 20 can be downsized (for example, the drive unit 20 can be downsized in the width direction or the like). As a result, the distance L2 between the crank arms can be made close to the distance between the crank arms of a normal bicycle (e.g., a so-called sport bicycle).

In addition, in this embodiment, although a sprocket having a shape in which the center side bulges to the right side is used as the drive sprocket 13, by using a small-sized bearing as the intermediate shaft bearing 35, the intermediate shaft bearing 35 or the portion of the first housing 22a holding the intermediate shaft bearing 35 can be disposed so as to enter the bulging portion of the drive sprocket 13, and the drive unit 20 can be further downsized (for example, the drive unit 20 can be downsized in the width direction or the like). As a result, the distance L2 between the crank arms can be made closer to a conventional bicycle (e.g., a so-called sport bicycle).

In the drive unit 20 of the electric power-assisted bicycle according to the third embodiment, the intermediate shaft 40 is disposed below the straight line connecting the crankshaft 7a and the motor shaft 21a when the motor shaft (the rotating shaft of the motor 21) 21a is disposed forward of the crankshaft 7a, but the present invention is not limited thereto. That is, as shown in fig. 17, when the motor shaft 21a is disposed rearward of the crankshaft 7a, the intermediate shaft 40 may be disposed above a straight line connecting the crankshaft 7a and the motor shaft 21 a.

In any case, such as when the intermediate shaft 40 is disposed on the right side or the left side of the line connecting the crankshaft 7a and the motor shaft 21a, the crankshaft 7a, the motor shaft 21a, and the intermediate shaft 40 are preferably disposed such that the angle of intersection of the line connecting the axis of the crankshaft 7a and the axis of the intermediate shaft 40 with respect to the line connecting the axis of the crankshaft 7a and the axis of the motor shaft 21a is within 30 degrees to 70 degrees in the clockwise direction, with the drive unit 20 being oriented in the direction of travel and viewed from the right side.

The same operational effects can be obtained by applying the same arrangement structure to the drive unit 20 incorporating the speed change mechanism as in the drive unit 20 of the electric power assisted bicycle according to the second embodiment.

Industrial applicability

The present invention is applicable to a drive unit for various electric power-assisted bicycles that can travel by applying an assist drive force generated by an electric motor to a manual drive force of a pedal force from a pedal, and to such an electric power-assisted bicycle.

Claims

1. A drive unit of an electric power-assisted bicycle, which is attached to an electric power-assisted bicycle capable of traveling by applying an assist drive force of an electric motor to a manual drive force of a pedaling force from pedals, and which is provided with the electric motor,

comprising: an attachment portion that is attached to a middle portion between a front wheel and a rear wheel of the electric power-assisted bicycle; a crankshaft insertion region through which a crankshaft to which a manual driving force from the pedal is transmitted is inserted; a driving force output wheel body that outputs a driving force,

the crankshaft and the motor are disposed at different axial centers from each other,

a base plate is disposed inside the drive unit, the base plate being disposed so as to have a portion overlapping with a stator of the motor when viewed along a side surface of the crankshaft,

the substrate is arranged so as to overlap with at least half of the area of the stator of the motor when viewed from the side,

the base plate is disposed between the motor and the first reduction gear.

2. The drive unit for an electric assist bicycle according to claim 1,

the substrate is disposed so as to overlap a region of the motor where the stator is disposed and a region around the crankshaft when viewed from the side.

3. The drive unit of an electric assist bicycle according to claim 1 or 2, wherein a motor rotation sensor that reads rotation of the motor is mounted on the base plate.

4. The drive unit of an electric power-assisted bicycle according to claim 1 or 2, wherein a crankshaft rotation sensor that reads rotation of a crankshaft is mounted on the base plate.

5. The drive unit of an electric power assisted bicycle according to claim 1 or 2,

a motor rotation sensor that reads rotation of the motor and a crankshaft rotation sensor that reads rotation of the crankshaft are mounted on the substrate.

6. The drive unit of an electric power assisted bicycle according to claim 1 or 2,

a plurality of substrates are provided, and the substrate having a portion overlapping with a stator of the motor is the substrate having the largest area among the plurality of substrates.

7. The drive unit of an electric power assisted bicycle according to claim 1 or 2,

the rotation of the motor is transmitted to a driving force output wheel body for outputting driving force via a two-stage speed reduction mechanism,

the reduction ratio, which is the ratio of the rotation speed of the motor to the rotation speed of the driving force output wheel body, is 30-37.

8. A drive unit for an electrically assisted bicycle according to claim 1 or 2, wherein the minimum radius around the crankshaft is 50 mm.

9. An electric power-assisted bicycle having a drive unit,

a reduction mechanism having a plurality of pairs of reduction gears is provided,

the speed reduction mechanism includes: an intermediate shaft disposed in parallel with the crankshaft; a plurality of counter shaft reduction gears provided to the counter shaft; a crankshaft-side reduction gear that is rotatably disposed on an outer periphery of the crankshaft and transmits a manual driving force and an assist driving force; a motor shaft reduction gear provided to the motor shaft,

has an intermediate shaft bearing for rotatably supporting the intermediate shaft,

the intermediate shaft is disposed between the crankshaft and the motor shaft with respect to the front-rear direction, and is disposed below a straight line connecting the crankshaft and the motor shaft when the motor shaft is disposed forward of the crankshaft, and is disposed above the straight line connecting the crankshaft and the motor shaft when the motor shaft is disposed rearward of the crankshaft,

the crankshaft, the motor shaft, and the intermediate shaft are arranged such that a line connecting the axis of the crankshaft and the axis of the intermediate shaft has an intersection angle of 30 to 70 degrees in the clockwise direction with respect to a line connecting the axis of the crankshaft and the axis of the motor shaft when viewed from the right side in the direction of travel of the electric power-assisted bicycle,

the base plate is disposed between the motor and the first reduction gear.

10. A driving power supply device comprising a driving unit of an electric power-assisted bicycle according to any one of claims 1 to 8 and an electric storage device for supplying electric power to the driving unit.

11. An electric power-assisted bicycle comprising the drive unit for an electric power-assisted bicycle according to any one of claims 1 to 8 or the drive power supply device according to claim 10.