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

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 assist bicycle and electric assist bicycle

technical field

The present invention relates to a drive unit and an electric-assisted bicycle which are mounted on an electric-assisted bicycle that can travel by applying a power-assisted driving force generated by an electric motor to a human-powered driving force from a pedaling force.

Background technique

There is known an electric power-assisted bicycle (also referred to as an electric bicycle), which includes a battery as a power source and a drive unit including an electric motor that is powered from the battery, and which applies a human drive force generated by a pedaling force applied to a pedal. Electric power-assisted bicycles (also called electric bicycles) that can easily travel even when going uphill or the like by assisting the driving force (assistance) have been widely known.

In this electric power-assisted bicycle, a drive unit having a built-in electric motor or the like is arranged at a portion where the crankshaft is provided. In the electric assist bicycle with such an arrangement structure, the heavy drive unit is disposed at a lower position in the center of the electric assist bicycle in the front-rear direction (ie, in the middle between the front wheel and the rear wheel). Therefore, the electric assist bicycle of this arrangement has the following advantages compared to the electric assist bicycle in which the motor is built in the hub of the front wheel or the hub of the rear wheel, that is, the front wheel and the rear wheel are easily lifted, even if there are steps on the running road, It is also possible to easily go over, etc., the handling of the vehicle body is good, and the running stability is also good.

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 a motor are mounted. Since this substrate mounts large electronic components such as FETs or many electronic components, it has a large area. In addition, as shown in Japanese Patent Laid-Open No. 2016-203735 and the like, for example, this substrate is also arranged around the crankshaft when viewed from the side (viewed from the direction of the crankshaft center).

However, in recent years, the distance from the crankshaft to the rear wheel or the front wheel of an electric power-assisted bicycle does not change much from that of a normal bicycle, and it is sometimes expected that the function as a bicycle can also be satisfactorily exhibited. However, when a drive unit in which a base plate is arranged around the crankshaft is used, the following problem arises. As the base plate becomes larger, a larger area is required around the crankshaft, and the drive unit also increases in size. Even if the arrangement of the drive unit is considered, The axle distance from the crankshaft to the rear wheel is also long.

SUMMARY OF THE INVENTION

The present invention is an invention to solve the above-mentioned problems, and an object of the present invention is to provide a drive unit for an electric-assisted bicycle that can minimize the area around the crankshaft, etc., can be reduced in size, and can function well as a bicycle, and an electric power-assisted bicycle including the drive unit. Assist the bike.

In order to solve the above-mentioned problems, a drive unit of an electric assist bicycle of the present invention is mounted on an electric assist bicycle that can travel by applying an auxiliary driving force of an electric motor to a human driving force from a pedaling force, and includes the electric motor, characterized in that: It has: a mounting part, which is mounted on the middle part between the front wheel and the rear wheel of the electric power-assisted bicycle; a crankshaft penetration area, which is penetrated by a crankshaft that transmits the human driving force from the pedal; a driving force output wheel A body that outputs driving force, the crankshaft and the electric motor are arranged at mutually different axes, and a substrate is arranged inside the drive unit so as to overlap with the stator of the electric motor when viewed along the side of the crankshaft part of the way configuration. 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 is the substrate having the largest area among the plurality of substrates.

According to this structure, the board|substrate is arrange|positioned so that it may have the part which overlaps with the stator of a motor, when it sees from a side, a board|substrate with a sufficiently large area can be used as a board|substrate. In addition, even in the case where the substrate (an additional substrate or a part of the substrate) is also arranged around the crankshaft, the area of the substrate around the crankshaft can be suppressed to a small extent. Therefore, by considering the arrangement of the drive unit, etc., the The distance from the crankshaft to the axle of the rear wheel is close to that of a normal bicycle.

Moreover, it is preferable that the said board|substrate is arrange|positioned so that the area|region more than half of the stator of an electric motor may overlap when viewed from the side. In addition, the substrate may be arranged so as to overlap from the region where the stator of the motor is arranged to the region around the crankshaft when viewed from the side.

In addition, a motor rotation sensor for reading the rotation of the motor or a crankshaft rotation sensor for reading the rotation of the crankshaft may be mounted on the substrate, thereby reducing the number of parts and the trouble of installation.

In addition, it is preferable that the rotation of the electric motor is transmitted to the driving force output wheel that outputs the driving force through the secondary reduction mechanism, and the ratio of the rotation speed of the electric motor to the rotation speed of the driving force output wheel, that is, the reduction ratio becomes 30 to 37 forms. In addition, it is preferable that the minimum radius around the crankshaft is 50 mm or less.

In addition, the present invention provides an electric power-assisted bicycle provided with a drive unit, characterized in that a reduction mechanism having a plurality of pairs of reduction gears is provided, the reduction mechanism having: an intermediate shaft arranged in parallel with the crankshaft; a plurality of The intermediate shaft reduction gear, which is arranged on the intermediate shaft; the crankshaft reduction gear, which is arranged on the outer circumference of the crankshaft so as to rotate freely, and transmits the human driving force and the boosting driving force; the motor shaft reduction gear, which is arranged on the motor shaft has an intermediate shaft bearing that rotatably supports the intermediate shaft, the intermediate shaft is disposed between the crankshaft and the motor shaft with respect to the front-rear direction, and when the motor shaft is disposed forward of the crankshaft, the intermediate shaft The intermediate shaft is disposed below the straight line connecting the crankshaft and the motor shaft, and when the motor shaft is disposed behind the crankshaft, the intermediate shaft is disposed above the straight line connecting the crankshaft and the motor shaft.

In this case, it is preferable that the line connecting the axis of the crankshaft and the axis of the intermediate shaft is relative to the axis of the crankshaft when viewed from the right side in the traveling direction of the electric assist bicycle. The crankshaft, the motor shaft, and the intermediate shaft are arranged so that the intersection angle with the axis line of the motor shaft is within 30 degrees to 70 degrees in the clockwise rotation direction.

In this configuration, a reaction force is generated when the reduction gears mesh with each other, and a large reaction force acts on the intermediate shaft. Therefore, at least one of the intermediate shaft bearings that rotatably supports the intermediate shaft is used that can support a large force. As a result of a large-sized bearing, the drive unit tends to increase in size (especially, the width direction dimension of the drive unit tends to increase).

However, according to the above-mentioned configuration (arrangement structure of the crankshaft, the motor shaft, and the intermediate shaft), the reaction forces to the intermediate shaft that are generated when the reduction gears mesh with each other can be suppressed to cancel each other and be minimized. As a result, the intermediate shaft bearing can be reduced in size (in the width direction and in the radial direction), and further, the drive unit can be reduced in size (for example, the drive unit can be reduced in size in the width direction).

In addition, the present invention provides a drive power supply device for an electric power-assisted bicycle, characterized by including the drive unit and an accumulator for supplying electric power to the drive unit.

In addition, an electric assist bicycle of the present invention is characterized by comprising the drive unit of the electric assist bicycle described in any one of the above or the drive power supply device.

According to the present invention, by arranging the substrate 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, and the substrate (an additional substrate or a part of the substrate) can be arranged around the crankshaft. Even in the case of , the area of the substrate around the crankshaft can be kept small. Therefore, by examining the arrangement of the drive unit, etc., the distance from the crankshaft to the axle of the rear wheel can be made close to that of a normal bicycle. In addition, by arranging the substrate so as to have a portion overlapping with the stator of the electric motor when viewed from the side, there is also a so-called sound insulating effect that the sound generated by the electric motor can be blocked by the substrate.

In addition, according to the present invention, the rotation of the motor is transmitted to the driving force output wheel body attached to the drive unit through the secondary reduction mechanism, and the speed reduction ratio is the ratio of the rotation speed of the motor to the rotation speed of the driving force output wheel body. With the configuration of 30 to 37, a smaller diameter gear can be used as the reduction gear coaxial with the crankshaft, and the diameter (radius and diameter) of the drive unit around the crankshaft can be reduced. Thereby, the distance from the crankshaft to the axle of the rear wheel can be made close to that of a normal bicycle (for example, a so-called sports bicycle).

In addition, by setting the minimum radius around the crankshaft (around the crankshaft) of the drive unit to 50 mm or less, the distance from the crankshaft to the axle of the rear wheel can be closer to that of a normal bicycle (for example, a so-called sports 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 closer to the straight line connecting the crankshaft and the motor shaft. Below, when the motor shaft is arranged behind the crankshaft, the intermediate shaft is arranged above the straight line connecting the crankshaft and the motor shaft, or the crankshaft is connected when the drive unit is viewed from the right side in the traveling direction. The crankshaft and the motor shaft are arranged so that the intersection angle between the axis of the crankshaft and the axis of the intermediate shaft relative to the 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. , Intermediate shaft. With this configuration, it is possible to suppress the reaction forces to the intermediate shaft which are generated when the reduction gears mesh with each other and minimize them, thereby reducing the size of the intermediate shaft bearing and thus the drive unit (for example, reducing the size of the drive unit in the width direction or the like). change). As a result, the distance between the crank arms can be made close to that of a normal bicycle (for example, a so-called sports bicycle).

Description of drawings

FIG. 1 is an overall left side view of an electric assist bicycle to which a drive unit according to an embodiment of the present invention is mounted.

2 is a plan cross-sectional view of a drive unit of the electric assist bicycle according to the same embodiment (first embodiment).

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

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

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

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

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

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

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

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

11 is a simplified plan view showing a motor shaft, an intermediate shaft, a crankshaft, and a reduction gear assembled to the drive unit of the electric assist bicycle according to the first embodiment of the present invention.

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

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

14 is a plan cross-sectional view of a drive unit of an electric assist bicycle according to a third embodiment of the present invention.

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

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

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

Detailed ways

(first embodiment)

Hereinafter, a drive unit of an electric assist bicycle according to an embodiment of the present invention and an electric assist bicycle to which the drive unit is mounted will be described based on the drawings. In addition, the left-right direction and the front-back direction in the following description refer to the direction which faces the traveling direction and a person rides on the electric assist bicycle 1 . In addition, the structure of this invention is not limited to the structure described below.

1 in FIG. 1 is an electric assist bicycle to which a drive unit according to an embodiment of the present invention is mounted. As shown in FIG. 1 , the electric assist bicycle 1 includes a metal frame 2 including a head tube 2a, a front fork 2b, a top tube 2c, a down tube 2g, a seat tube 2d, a chain frame 2e, a seat fork 2f, and the like Structure: front wheel 3, which is rotatably mounted on the lower end of the front fork 2b; rear wheel 4, which is rotatably mounted on the rear end of the chain frame 2e; handlebar 5, which changes the direction of the front wheel 3; saddle 6 , which is used for the passenger to sit; the crank 7 and the pedal 8 to which the human driving force composed of the pedaling force is applied; A drive unit (drive unit device) 20 including a control unit that controls various electrical components including the electric motor 21, and the like; a battery 12 composed of a secondary battery that supplies electric power for driving to the electric motor 21; The part 18 is mounted on the handlebar 5, etc., and can be operated by the rider, etc., and can switch the power supply of the electric assist bicycle 1, set and change the driving mode, etc.; (referred to as front sprocket, crank sprocket and front gear) 13, which are installed to rotate integrally through the same axis as the crankshaft 7a, and output the combined force of the human driving force and the assist driving force; as a rear wheel body The rear sprocket 14 (sometimes also referred to as rear gear) is mounted on the hub (also referred to as rear hub) 9 of the rear wheel 4; the chain 15 as an endless driving force transmission body, which can be used throughout the driving sprocket 13 and the rear sprocket 14 are wound in a ring shape or the like while rotating. In addition, a drive power supply device (drive unit module) is constituted by the drive unit 20 and the battery 12 .

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

In addition, although the battery 12 is an example of a storage battery, a secondary battery is preferable, but the said storage battery may be a capacitor|condenser or the like. The crank 7 is composed of crank arms 7 b provided on the left and right, respectively, and a crank shaft 7 a connecting the left and right crank arms 7 b to each other, and a pedal 8 is rotatably attached to the end of the crank arms 7 b.

As shown in FIG. 1 , in the electric power-assisted bicycle 1 , the drive unit 20 is arranged at an intermediate position between the front wheel 3 and the rear wheel 4 , and more specifically, at a portion where the crankshaft 7 a penetrates. Furthermore, by adopting such an arrangement structure, the drive unit 20 having a large weight is arranged in the center in the front-rear direction of the electric assist bicycle 1 . As a result, the front wheel 3 and the rear wheel 4 can be easily lifted, and even if there are steps on the running road, it can be easily passed over, etc., the handling of the body (frame 2, etc.) of the electric assist bicycle 1 is good, and the running stability is also good. .

As shown in FIG. 2 , the drive unit 20 is constituted by a unit casing 22 including first to third casings 22a to 22c as a casing and the like, and a crankshaft 7a connects the drive unit 20 (in the present embodiment, provided in the drive unit 20 The crankshaft insertion area 16) in the rear part penetrates along the left and right sides. In addition, the unit case 22 is integrally formed with an attachment portion 22d for attaching the drive unit 20 to an intermediate portion between the front wheel and the rear wheel in the above-described electric power-assisted bicycle. In addition, on the outer periphery of the crankshaft 7a, a substantially cylindrical manpower transmission body 28 that transmits the manpower driving force from the crankshaft 7a, an interlocking cylinder 23 that transmits the manpower driving force from the manpower transmitting body 28, and an interlocking cylinder 23 are provided. The human driving force of the body 23 is transmitted via the one-way clutch (one-way clutch for cutting off the assisting driving force) 30 and the like, and the resultant force which combines the human driving force and the assisting driving force from the electric motor 21 is transmitted to the driving sprocket 13 . body 29.

In addition, in the unit case 22 of the drive unit 20, a speed reduction mechanism 25 for decelerating the rotation of the electric motor 21 and transmitting it to the side of the resultant force transmission body 29 (in this embodiment, the intermediate shaft 40), and a power-assisted driving force ( A motor 21 that is a power assist) drive source, and a board (also referred to as a drive board or a main board) 24 on which electronic components for various electrical controls are provided is also provided. The control unit is constituted by the substrate 24 and electronic components (FET (Field Effect Transistor) 24a, a capacitor, a microcomputer, etc.) mounted on the substrate. In addition, as shown in FIGS. 2 and 3 , the positions of the axis of the rotating shaft 21a of the electric motor 21, the axis of the crankshaft 7a, and the axis of the intermediate shaft 40 described later are different from each other. In addition, in this embodiment, the rotating shaft 21a of the electric 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 the straight line connecting the crankshaft 7a and the motor shaft 21a. In addition, in the drive unit 20 (specifically, in the unit case 22 of the drive unit 20 ), parts other than both ends of the crankshaft 7 a , the human power transmission body 28 , the interlocking cylinder 23 , and the resultant force transmission body are provided. 29. The speed reduction mechanism 25, the electric motor 21, the torque sensor 31 to be described later, the rotation detector 11, the rotation detector (rotation sensor) 10, and the like. Then, the human driving force and the assist driving force are combined in the drive unit 20, and the combined combined force is configured to be output from the drive sprocket 13 provided outside the drive unit 20 (specifically, outside the unit case 22 of the drive unit 20). .

The drive unit 20 will be described in more detail. As shown in FIGS. 2 and 3 , the crankshaft 7a is rotatably arranged by bearings (crankshaft bearings) 26 and 27 while penetrating the rear portion of the drive unit 20 along the left and right. Then, on the outer periphery of the left side portion of the crankshaft 7a, a cylindrical human power transmission body 28 is fitted through a serration portion (or a spline portion) 7c while rotating integrally with the crankshaft 7a. In addition, a serrated portion (or spline portion) 28b is also formed on the inner circumference of the human power transmission body 28 at a portion corresponding to the serrated portion (or spline portion) 7c of the crankshaft 7a, and is aligned with the serrated portion (or spline portion) of the crankshaft 7a. part) 7c engage.

A magnetostriction generating portion 31b to which magnetic anisotropy is imparted is formed on the outer peripheral surface of the human power transmitting body 28, and a coil 31a is arranged on the outer periphery through a certain gap (space), and these magnetostriction generating portions 31b and The coil 31 a constitutes a magnetostrictive torque sensor (human force detection unit) 31 . Thereby, the human driving force from the crankshaft 7 a is transmitted to the human power transmitting body 28 , and the human driving force is detected by the torque sensor 31 . In addition, in this magnetostrictive torque sensor 31 , the magnetostriction generating portion 31 b is formed in a spiral shape of +45 degrees and -45 degrees, for example, with respect to the axial center direction of the human power transmission body 28 . Then, when the human power driving force is transmitted to the human power transmission body 28, strain is generated in the magnetostriction generating portion 31b on the surface of the human power transmission body 28, and an increase portion and a decrease portion of the magnetic permeability are generated. Therefore, the measurement coil 31a is configured to pass The inductance difference is able to detect the magnitude of torque (human driving force).

The interlocking cylindrical body 23 is arranged in a state of being rotatable with respect to the crankshaft 7a at a portion adjacent to the right side of the human power transmission body 28 on the outer periphery of the crankshaft 7a. Furthermore, the serrated portion (or spline portion) 28a formed on the outer periphery of the right end portion of the human power transmission body 28 and the serrated portion (or splined portion) 23a formed on the inner periphery of the left end portion of the interlocking cylindrical body 23 are fitted with each other, and the interlocking The cylindrical body 23 rotates integrally with the human power transmission body 28 . In addition, in this embodiment, the serrations (or splines) 23a formed on the inner periphery of the left end portion of the interlocking cylinder 23 are fitted to the serrations (or splines) 28a of the human power transmission body 28 from the outside.

In addition, in this embodiment, the rotation detection body 11 for detecting the rotation state of the interlocking cylindrical body 23 is attached to the outer periphery of the left part of the interlocking cylindrical body 23 . In addition, a rotation detector (rotation sensor) 10 serving as a crankshaft rotation sensor is attached and fixed to the unit case 22 side so as to face the rotation detector 11 from the outer peripheral surface. For example, the photosensors of the rotation detector 10 having an emitting part and a light receiving part are arranged in a line along the rotation direction of the rotation detector 11 (not shown), and the rotation detector 11 has a comb ( Comb) tooth-like a plurality of teeth. Furthermore, in the case of having the tooth portion of the rotation detector 11, by reflecting and receiving the emitted light, the light receiving portion of the rotation detector 10 electrically detects the incident state and the non-incident state of the light, and detects the light incident state and the non-incident state. The received signal is input to the control unit to detect the rotational speed (rotation amount) and the rotational direction of the interlocking cylinder 23 . In addition, instead of the optical sensor, a magnetic sensor such as a Hall IC may be provided to detect the rotational speed (rotation amount) and the rotational direction of the interlocking cylinder 23 . Here, the interlocking cylindrical body 23 rotates integrally with the human power transmitting body 28, and the manpower transmitting body 28 rotates integrally with the crankshaft 7a. Therefore, the crankshaft 7a can also be detected by detecting the rotation amount and the rotational direction of the interlocking cylindrical body 23. and the rotation speed (rotation amount) and rotation direction of the pedal 8 .

In addition, on the outer periphery of the right side portion of the interlocking cylindrical body 23 , a resultant force transmitting body 29 is disposed via a one-way clutch (one-way clutch for cutting off the assist driving force) 30 . Then, when the pedal 8 is stepped on to advance, the human driving force transmitted to the interlocking cylindrical body 23 is transmitted to the resultant force transmission body 29 via the one-way clutch 30 .

The motor 21 is rotatably supported by the motor shaft bearings 32 and 33 to support the rotation shaft 21 a and the rotor 21 b. Moreover, the rotating shaft 21a of the electric motor 21 protrudes rightward, and the motor shaft reduction gear 39 mentioned later is formed in the outer periphery of this protruding part.

The speed reduction mechanism 25 includes an intermediate shaft 40 arranged in parallel with the crankshaft 7 a , and two pairs of reduction gears including a large-diameter reduction gear (first reduction gear: crankshaft side reduction gear) 36 formed on the left portion of the resultant force transmission body 29 . 36 to 39, etc., constitute a secondary deceleration mechanism. The speed reduction mechanism 25 combines the human driving force transmitted through the crankshaft 7 a and the assist driving force transmitted from the electric motor 21 , and transmits the resultant force obtained by combining the human driving force and the assist driving force to the combined force transmission body 29 .

The intermediate shaft 40 extends leftward and rightward at the center portion in the front-rear direction of the drive unit 20, and is rotatably supported by bearings (intermediate shaft bearings) 34 and 35 in a posture parallel to the crankshaft 7a. A large-diameter second counter-shaft reduction gear 37 , a small-diameter third counter-shaft reduction gear 38 , and a one-way clutch 42 for cutting off the human driving force are attached to the counter shaft 40 .

The one-way clutch 42 for cutting off the human driving force is disposed between the outer circumference of the intermediate shaft 40 and the inner circumference of the second intermediate shaft reduction gear 37 , and cuts off the human driving force from the pedal 8 . That is, the one-way clutch 42 is configured so that, when the electric motor 21 is not driven and the assist driving force is not generated, the human driving force from the pedal 8 is cut off by the one-way clutch 42 for cutting off the human driving force, and is not The rotor 21b of the electric motor 21 needs to be rotated. On the other hand, when the electric motor 21 is driven and rotated, the intermediate shaft 40 and the second intermediate shaft reduction gear 37 are connected via the one-way clutch 42 , and the second and third intermediate shaft reduction gears 37 and 38 are connected to the intermediate shaft 40 . rotate together as one.

Further, the small-diameter motor shaft reduction gear 39 formed on the rotating shaft 21 a of the electric motor 21 meshes with the large-diameter second counter shaft reduction gear 37 . Therefore, when the electric motor 21 rotates and outputs the assist driving force, the rotation of the electric motor 21 The speed is reduced, and the torque of the booster driving force from the electric motor 21 is amplified and transmitted to the intermediate shaft 40 side. In addition, since the small-diameter third countershaft 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 booster driving force transmitted to the countershaft 40 is further amplified and directed toward the first reduction gear 36. The reduction gear 36 transmits. Further, in the resultant force transmission body 29 in which the first reduction gear 36 is integrally formed, the human driving force and the assisting driving force from the electric motor 21 are combined and output from the drive sprocket 13 as the driving force output wheel body. Here, the ratio of the rotational speed of the electric motor 21 to the rotational speed of the drive sprocket 13 , that is, the reduction ratio is set to 30 to 37 (30 or more and 37 or less). In addition, the minimum radius around the crankshaft 7a (around the crankshaft) of the drive unit 20 is set to 50 mm or less.

In addition, in this embodiment, in the unit case 22 of the drive unit 20, only one substrate 24 having a relatively large area is provided as a substrate. Further, the base plate 24 is arranged such that when the drive unit 20 is viewed from the side of the crankshaft 7a (when viewed from the side in the axial direction of the crankshaft 7a), as shown in FIG. The stator (more specifically, the area|region in which the stator core is provided in the stator of the electric motor 21) 21c overlaps. In addition, in this embodiment, the board|substrate 24 is arrange|positioned so that half or more of the area of the stator 21c of the electric motor 21 may overlap. In addition, in this embodiment, the board|substrate 24 is arrange|positioned so that it may overlap from the area|region where the stator 21c of the electric motor 21 is arrange|positioned to the area|region surrounding the crankshaft 7a.

In addition, in this embodiment, when viewed from the side, as shown in FIG. 3 , the substrate 24 is also provided in a region overlapping the rotor 21 b of the motor 21 . Further, the substrate 24 is arranged so that more than half of the area of the rotor 21b of the motor 21 overlaps. That is, in this embodiment, when viewed from the side, as shown in FIG. 3 , the substrate 24 is also provided in a region overlapping with the motor 21 (the entire motor), and the substrate 24 overlaps more than half of the area of the motor 21 . configuration.

In addition, in this embodiment, when viewed from the side, as shown in FIG. 3 , the substrate 24 is also provided in a region where the first reduction gear 36 and the stator 21 c of the electric motor 21 do not overlap. In addition, as shown in FIG. 2 , in plan view (or front view), the base plate 24 is provided between the motor 21 and the first reduction gear 36 , the resultant force transmission body 29 , and the interlocking cylinder 23 . In addition, when viewed from the front (when viewed in the front-rear direction), as schematically shown in FIG. In addition, in this embodiment, when viewed from the side, as shown in FIG. 3 , the base plate 24 is provided in a region that does not overlap with the second reduction gear 37 . In addition, when viewed from the front (when viewed in the front-rear direction), as schematically shown in FIG. 2 , the base plate 24 is provided in a region that does not overlap with the second reduction gear 37 . However, it is not limited to this case, and when the base plate 24 is viewed from the side, it may be provided so as to partially overlap the second reduction gear 37 .

In addition, in this embodiment, the rotation detector (rotation sensor) 10 (more specifically, the connection leg of the rotation detector (rotation sensor) 10 is mounted as a crankshaft rotation sensor that reads the rotation of the crankshaft is mounted on the substrate 24 . department). In addition, in this embodiment, as shown in FIG. 2 , in plan view, the substrate 24 is provided on the rotation detector 11 or the rotation detector (rotation sensor) 10 and the bearing 26 supporting the crankshaft 7a and the like (driven from the crankshaft 7a) Between the bearing 26 ) or the torque sensor 31 supported on the opposite side of the sprocket 13 .

In addition, in this embodiment, in the rotor 21b of the electric motor 21, a plurality of magnets are arranged in the circumferential direction so that the magnetic poles of the adjacent magnets are different, but a substantially cylindrical shape having the same magnetic pole as the magnetic pole is arranged. Shaped magnetism imparting member 21d. The outer peripheral portion of the magnetism imparting member 21d has a shape protruding to the right, and a motor rotation sensor 43 for reading the rotation of the motor 21 is disposed so as to face the end 21da of the protruding magnetism imparting member 21d. Furthermore, the motor rotation sensor 43 is mounted on the substrate 24 .

In addition, only the end portion 21da of the magnetism imparting member 21d may impart magnetism in the same manner as the arrangement of the rotor 21b of the electric motor 21 . In addition, in this embodiment, the magnetism imparting member 21d also serves as a region where the reduction mechanism 25 having the plurality of reduction gears 36 to 39 and the like is arranged (the reduction mechanism arrangement region) and the region where the electric motor 21 is arranged ( Partitioning parts that separate the motor arrangement area). Furthermore, it is intended to prevent grease or the like that reduces the friction between the reduction gears 36 to 39 from entering the side of the electric motor 21 , but it is not limited to this case. In addition, 21ca in FIG. 2 is a connection wire for energizing the coil of the stator 21c.

In the above configuration, when the pedal 8 is stepped on during forward travel, the human driving force based on the pedaling force applied to the pedal 8 is transmitted from the crankshaft 7a to the human power transmission body 28, the interlocking cylinder 23, and the resultant force body 29. The above-mentioned The human driving force is detected by the torque sensor 31 provided in the human power transmitting body 28 . Then, the auxiliary driving force corresponding to the above-mentioned human driving force is transmitted to the resultant force transmission body 29 via the reduction gear 36 of the reduction mechanism 25 and the like, 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 . . Thereby, even when going up a slope or the like, it is possible to travel easily by applying the assisting driving force (assistance) of the electric motor 21 corresponding to the human driving force.

In addition, according to the above configuration, the substrate 24 is disposed so as to have a portion overlapping with the stator 21c of the motor 21 when viewed from the side, so that a substrate 24 having a sufficiently large area can be used. In addition, even when the substrate 24 is arranged around the crankshaft 7a as in this embodiment, the area of the region around the crankshaft 7a of the substrate 24 can be kept small. The distance from the crankshaft 7a to the axle of the rear wheel 4 can be made close to that of an ordinary bicycle (for example, a so-called sports bicycle).

In addition, as described above, the substrate 24 is disposed so as to overlap more than half of the area of the stator 21c of the motor 21 when viewed from the side, thereby minimizing the area of the substrate 24 around the crankshaft 7a. Therefore, the distance from the crankshaft 7a to the axle shaft of the rear wheel 4 of the electric assist bicycle 1 can be made closer to the distance of an ordinary bicycle (for example, a so-called sports bicycle). In addition, by arranging the substrate 24 so as to have a portion overlapping with the stator 21 c of the motor 21 in side view, the substrate 24 can block the sound generated in the motor 21 . That is, as mentioned above, the board|substrate 24 is arrange|positioned so that half or more of the area of the stator 21c of the electric motor 21 may overlap, and the sound insulation effect can be improved further.

In the above-described embodiment, the motor rotation sensor 43 for reading the rotation of the motor 21 and the rotation detector 10 as a crankshaft rotation sensor for reading the rotation of the crankshaft 7 a 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. Furthermore, in the present invention, as schematically shown in FIG. 2 , in plan view (or front view), the base plate 24 is provided between the motor 21 and the first reduction gear 36 , the resultant force transmission body 29 , and the interlocking cylindrical body 23 , Therefore, there is an advantage that the motor rotation sensor 43 and the rotation detector 10 serving as the crankshaft rotation sensor can be easily mounted on the substrate 24 . 2 , the substrate 24 is provided so as to overlap the rotor 21b or the magnetism imparting member 21d of the motor 21 when viewed from the side. Therefore, there is an advantage that the motor rotation sensor 43 can be easily mounted on the substrate 24 .

However, it is not limited to this, and as shown in FIG. 4 , the crankshaft rotation sensor assist board 24A to which the rotation detector 10 serving as the crankshaft rotation sensor is mounted may be provided separately from the board (main board) 24 , and the The assist board 24A for the crankshaft rotation sensor is connected to the board (main board) 24 (a first modification of the first embodiment). Alternatively, as shown in FIG. 5 , the motor rotation detection power assist board 24B on which the motor rotation sensor 43 is mounted may be provided separately from the board (main board) 24, and the motor rotation detection power assist board 24B may be provided. It is connected to a substrate (main substrate) 24 (a second modification of the first embodiment). In addition, in this embodiment, as shown in FIGS. 4 and 5 , when viewed from above, the substrate (main substrate) 24 is provided on the rotation detector 11 or the rotation detector (rotation sensor) 10 and the bearing 26 (crankshaft) that supports the crankshaft 7a and the like. 7a is provided between the bearing 26) or the torque sensor 31 on the opposite side to the side where the drive sprocket 13 is provided. In addition, even in these cases, the substrate (main substrate) 24 is preferably larger (larger area) than the assist substrate 24A for crankshaft rotation sensor or the assist substrate 24B for motor rotation detection.

In addition, the rotation of the electric motor 21 is configured so that the rotation of the electric motor 21 is transmitted to the driving sprocket 13 as the driving force output wheel body through the secondary reduction mechanism 25, and the ratio of the rotation speed of the electric motor 21 to the rotation speed of the driving sprocket 13, that is, the reduction ratio becomes 30 to 37 forms. Thereby, as the first reduction gear 36 coaxial with the crankshaft 7a, a gear having a small diameter can be used. As a result, the diameter (radius and diameter) around the crankshaft 7a in the drive unit 20 can be reduced, and further, by considering the arrangement of the drive unit 21 (for example, arranging the electric motor 21 on the front side of the crankshaft 7a), etc., the The distance from the crankshaft 7a to the axle of the rear wheel 4 is close to that of an ordinary bicycle (for example, a so-called sports bicycle).

In addition, by setting the minimum radius around the crankshaft 7a (around the crankshaft) of the drive unit 20 to 50 mm or less, the distance from the crankshaft 7a to the axle of the rear wheel 4 can be made closer to that of an ordinary bicycle (for example, a so-called sports bicycle). . Furthermore, by setting the minimum radius around the crankshaft 7a (around the crankshaft) of the drive unit 20 to 45 mm or less, the distance from the crankshaft 7a to the axle of the rear wheel 4 can be made closer to that of an ordinary bicycle (for example, a so-called sports bicycle) .

(Second Embodiment)

In the above-described embodiment, the case where the speed reduction ratio of the speed reduction mechanism 25 is constant has been described, but the present invention is not limited to this, and a device having a speed change function that can selectably switch between a plurality of speed reduction ratios (in this embodiment, two speed shift stages) may be used. The speed reduction mechanism 25A is provided in the drive unit 20 .

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

The speed reduction mechanism 25A includes: a rotation transmission cylinder 49 which is rotatably arranged on the outer periphery of the crankshaft 7a, and which transmits the rotation of the interlocking cylinder 23 via a one-way clutch (one-way clutch for cutting off the assist driving force) 30; a low-speed speed change gear (also referred to as a crankshaft-side low-speed speed change gear) 36A, which extends radially outward from the right cylindrical portion of the rotation transmission tube 49 and is integrally formed; Between the bodies 29, the driving force of the crankshaft-side low-speed speed change gear 36A can be transmitted to the resultant force transmission body 29; A low-speed speed change gear (also referred to as an intermediate shaft-side low-speed speed change gear) 38A, which is integrally formed with the intermediate shaft 40 and meshes with the crankshaft-side low-speed speed change gear 36A; The shaft 40 is integrally formed, and meshes with a tooth portion (or a sawtooth portion or a spline portion) 55b formed on the inner peripheral side of the high-speed clutch 55 to be described later; the high-speed clutch 55 is provided on the intermediate shaft teeth of the intermediate shaft 40 The outer circumference of the portion 40a and its right side region can transmit the resultant force from the intermediate shaft 40 to the crankshaft side high-speed speed change gear 36B and the resultant force transmission body 29; An engaging pawl portion) 38B of the high-speed clutch 55 is composed of an engaging pawl removably retractable to the outer peripheral side from the high-speed clutch 55 (specifically, the main body portion 55a of the high-speed clutch 55), and is connected to the crankshaft side high speed The speed change gear 36B can be freely engaged and disengaged (see FIGS. 9 and 10 ); the speed change body 61 can be freely engaged and disengaged from the right side of the intermediate shaft side high speed speed change tooth portion 38B from the outer peripheral side, and is selected according to the selection. The shift stage movement; the shift movement arm 62 and the like, which engage with the shift stage switching body 61 and move the shift stage switching body 61 in the crankshaft direction.

Then, when the pedal 8 is advanced, the human driving force transmitted to the interlocking cylinder 23 is transmitted to the rotation transmission cylinder 49 . In addition, in this embodiment, the high-speed clutch 55 is arranged 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 speed change gear 36A is larger than the diameter of the crankshaft-side high-speed speed change gear 36B, and the diameter of the intermediate shaft side low-speed speed change gear 38A is smaller than the diameter of the intermediate shaft side high-speed speed change gear portion 38B. Thereby, the rotational force of the intermediate shaft 40 is transmitted to the crankshaft-side low-speed speed change gear 36B and the rotation transmission tube 49 at a low speed, and is transmitted to the crankshaft side high speed speed change gear 36B at a high speed.

In addition, it is preferable that the arm 62 for shifting movement is driven by the electric shifting device 51 (shown simply in FIG. 7 ) provided inside the drive unit 20 (or outside the drive unit), and for example, it is preferable to set the shift stage on the operation unit 18 at hand. The switch for switching is configured to switch the gear stage. However, it is not limited to this, and the shift moving arm (shift portion that moves via a lead wire or the like) 62 may be provided in the vicinity of the handlebar.

When the low speed stage is selected, as shown in FIGS. 6 and 8 , the shift stage switching body 61 is moved to the left position by the shift moving arm 62 , and the engagement claw of the high stage clutch 55 is freely retractable. The intermediate shaft-side high-speed speed change gear portion 38B is constructed so as to be pushed down and separated from the crankshaft-side high-speed speed change gear 36B. Therefore, the human driving force transmitted from the interlocking cylinder 23 side via the one-way clutch (one-way clutch for cutting off the booster driving force) 30 and the assisting force transmitted from the motor side via the intermediate shaft 40 or the intermediate shaft side low-speed transmission gear 38A The driving force is transmitted to and combined with the rotation transmission cylinder 49 in a state of low rotation, and this rotation driving force (resultant force) is output from the drive sprocket 13 via the low-speed clutch 51 and the resultant force transmission body 29 .

When the high-speed stage is selected, as shown in FIGS. 9 and 10 , the shift-stage switching body 61 is moved to the right position by the shift-moving arm 62 , and can be shifted with the crankshaft side high-speed stage of the high-speed clutch 55 . The claws engaged with the gear 36B (specifically, the teeth of the crank-side high-speed speed change gear 36B) can stand up, and the rotation of the crank-side high-speed speed change gear 36B can be transmitted to the resultant force transmission body 29 . Therefore, the human driving force transmitted from the side of the interlocking cylinder 23 via the one-way clutch (one-way clutch for cutting off the booster driving force) 30 is transmitted to the intermediate shaft via the crank-side low-speed transmission gear 36A and the intermediate-shaft side low-speed transmission gear 38A. 40 is transmitted, and the auxiliary driving force is combined to form a resultant force. Then, the resultant force is transmitted to the resultant force transmission body 29 via the high-speed clutch 55 via the intermediate shaft side high-speed speed change gear 38B and the crankshaft side high-speed speed change gear 36B, and is output from the drive sprocket 13 while rotating at a relatively high speed. In addition, at this time, since the resultant force transmission body 29 rotates at a higher speed than the rotation transmission cylinder 49, the low-speed clutch 51 is idling.

In this way, by using the drive unit 20 , it is also possible to switch the gear stage within the drive unit 20 . In addition, in this embodiment, by disposing the substrate 24 and the like in the same manner as in the above-described embodiment, the same effect can be obtained. In addition, the ratio of the rotation speed of the electric motor 21 to the rotation speed of the drive sprocket 13 in the low speed stage, that is, the reduction ratio is 30 to 37, and the reduction ratio in the high speed stage is constituted so as to be less than or equal to that, and the crankshaft 7a is concentric with the crankshaft 7a. The crankshaft-side low-speed speed change gear 36A (and the crankshaft-side high-speed speed change gear 36B) can use a gear with a smaller diameter, and the same effect can be obtained.

Further, in the above-described 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 to this, and may be provided in the outer peripheral region of the crankshaft 7a. Also, as in the above-described embodiment, the crankshaft rotation sensor assist board 24A to which the rotation detector 10 serving as the crankshaft rotation sensor is mounted may be provided separately from the board (main board) 24, and the crankshaft may be The rotation sensor power 24A is connected to the substrate (main substrate) 24 . Alternatively, the assisting board 24B for motor rotation detection on which the motor rotation sensor 43 is mounted may be provided separately from the board (main board) 24 , and the assisting board 24B for motor rotation detection may be connected to the board (main board) 24 . .

In the above-described embodiments (first and second embodiments), the motor shaft (rotating shaft 21a of the motor 21 ) is disposed forward of the crankshaft 7a, and the intermediate shaft 40 is disposed below the straight line connecting the crankshaft 7a and the motor shaft 21a. . In addition, the second and third intermediate shaft reduction gears 37 and 38 attached to the intermediate shaft 40, the motor shaft reduction gear 39 attached to the motor shaft 21a, and the first reduction gear (crankshaft side reduction gear) arranged on the outer periphery of the crankshaft 7a 36 As shown in Fig. 11, all of them are made of helical (helical tooth) gears to achieve quietness. 11 corresponds to the first embodiment. In addition, when the motor 21 is driven to output the assist driving force, the motor shaft 21 a and the motor shaft reduction gear 39 rotate in the clockwise direction (clockwise direction) when viewed from the right side. The second countershaft reduction gear 37 , the countershaft 40 , and the third countershaft reduction gear 38 rotate in the counterclockwise direction (counterclockwise direction) when viewed from the right side, and the first countershaft reduction gear 38 meshes with the third countershaft reduction gear 38 . The crankshaft side reduction gear 36 rotates in the clockwise direction (clockwise direction) when viewed from the right side.

In this configuration, as shown in FIG. 12 , when the reduction gears 36 to 39 of the reduction mechanism 25 mesh with each other, force vectors (reaction forces) V1 to P6 are generated and act on the intermediate shaft 40 as shown in FIG. 13 . 12 shows the force vector (reaction force) acting on the contact portion of the gear (finally, the force vector (reaction force) related to the intermediate shaft 40 ), and FIG. 13 shows the state in which the force vector (reaction force) acts on the intermediate shaft 40 (The state where the force vector is concentrated on the axis of the intermediate shaft 40).

In FIGS. 12 and 13 , V1 is the connection force vector to the intermediate shaft bearing 35 generated by the meshing of the motor shaft reduction gear 39 and the second intermediate shaft reduction gear 37 , and V2 is the motor shaft reduction gear 39 and the second intermediate shaft reduction gear. The separation force vector to the countershaft bearing 35 by the meshing of 37 , V3 is the load vector of the thrust to the countershaft bearing 35 by the meshing of the motor shaft reduction gear 39 and the second countershaft reduction gear 37 . In addition, V4 is the connection force vector to the intermediate shaft bearing 35 generated by the meshing of the first reduction gear (crankshaft side reduction gear) 36 with the third countershaft reduction gear 38 , and V5 is the first reduction gear (crankshaft side reduction gear) 36 The separation force vector to the countershaft bearing 35 generated by the meshing with the third countershaft reduction gear 38, V6 is the separation force vector generated by the meshing of the first reduction gear (crankshaft side reduction gear) 36 with the third countershaft reduction gear 38 to the countershaft The load vector of the thrust force of the bearing 35 , V7 is the reaction force (resultant force) vector acting on (merging) the intermediate shaft 40 .

According to the above arrangement, the force vectors V1 to P6 on the intermediate shaft 40 generated when the reduction gears 36 to 39 are meshed with each other are less likely to cancel each other out, and therefore, the force vectors V1 to P6 act on the intermediate shaft 40 relatively in a state where these force vectors V1 to P6 are combined. Great force vector V7. Therefore, the intermediate shaft bearings 34 and 35 of the intermediate shaft 40 are rotatably supported, and in particular, the intermediate shaft bearing 35 on the right side is closer to the third intermediate shaft reduction gear 38 that meshes with the first crank-side reduction gear 36 that transmits the resultant force. Since a large reaction force is received, a large-sized gear that can withstand a large force is used, and as a result, the drive unit 20 is enlarged in size (especially in the present embodiment, the width of the portion of the drive unit 20 where the intermediate shaft 40 is arranged) direction size becomes larger).

In this way, when the size of the drive unit 20 is increased and the dimension in the width direction of the drive unit 20 is increased, the distance L1 (see FIG. 2 ) between the left and right crank arms 7b is greatly increased compared to a normal bicycle (for example, a so-called sports bicycle) , and therefore, there is a difficulty in that it is difficult to approach the function as an ordinary bicycle (for example, a so-called sports bicycle).

In order to deal with this difficulty, in the drive unit 20 of the electric power-assisted bicycle according to the third embodiment of the present invention shown in FIGS. 14 to 16 , the rotating shaft 21 a of the electric motor 21 , the intermediate shaft 40 , the crank shaft 7 a ( This arrangement is the same as the above-mentioned embodiment), but unlike the above-mentioned embodiment, the intermediate shaft 40 is arranged above the straight line connecting the crankshaft 7a and the motor shaft 21a. In this case, as shown in FIG. 15 , with the drive unit 20 facing the traveling direction and viewed from the right side, the line connecting the axis of the crankshaft 7 a and the axis of the intermediate shaft 40 is relative to the The crankshaft 7a, the motor shaft 21a, and the intermediate shaft 40 are arranged so that the angle α intersecting the line A connecting the axis of the crankshaft 7a and the axis of the motor shaft 21a is within 30 to 70 degrees in the clockwise rotation direction.

In addition, compared with the drive unit 20 of the first embodiment described above, the drive unit 20 of the electric assist bicycle according to the third embodiment mainly includes the arrangement of the intermediate shaft 40, the crankshaft 7a, the motor shaft 21a, and the structure of the bearing accompanying the arrangement. (size, etc.) are different, and other structures are the same as those of the drive unit 20 of the above-described first embodiment. That is, the second and third intermediate shaft reduction gears 37 and 38 attached to the intermediate shaft 40, the motor shaft reduction gear 39 attached to the motor shaft 21a, and the first reduction gear (crankshaft side reduction gear) arranged on the outer periphery of the crankshaft 7a 36 As shown in Figure 11, they are all set as helical (helical) gears to achieve quietness. In addition, when the motor 21 is driven to output the assist driving force, the motor shaft 21 a and the motor shaft reduction gear 39 rotate in the clockwise direction (clockwise direction) when viewed from the right side. The second countershaft reduction gear 37 , the countershaft 40 , and the third countershaft reduction gear 38 rotate in the counterclockwise direction (counterclockwise direction) when viewed from the right side, and the first countershaft reduction gear 38 meshes with the third countershaft reduction gear 38 . The crankshaft side reduction gear 36 rotates in the clockwise direction (clockwise direction) when viewed from the right side.

In this structure, as shown in FIG. 15 , when the reduction gears 36 to 39 of the reduction mechanism 25 mesh with each other, force vectors (reaction forces) V11 to P16 are generated, which act on the intermediate shaft 40 as shown in FIG. 16 . 15 shows the force vector (reaction force) acting on the contact portion of the gear (the force vector (reaction force) related to the intermediate shaft 40 in the end), and FIG. 16 shows the state in which the force vector (reaction force) acts on the intermediate shaft 40 (The state where the force vector is concentrated on the axis of the intermediate shaft 40).

In FIGS. 15 and 16, V11 is the connection force vector to the intermediate shaft bearing 35 generated by the meshing of the motor shaft reduction gear 39 and the second intermediate shaft reduction gear 37, and V12 is the motor shaft reduction gear 39 and the second intermediate shaft reduction gear The separation force vector to the countershaft bearing 35 by the meshing of the gear 37, V13 is the load vector of the thrust to the countershaft bearing 35 by the meshing of the motor shaft reduction gear 39 and the second countershaft reduction gear 37. In addition, V14 is the connection force vector to the countershaft bearing 35 generated by the meshing of the first reduction gear (crankshaft side reduction gear) 36 with the third countershaft reduction gear 38 , and V15 is the first reduction gear (crankshaft side reduction gear) 36 The separation force vector to the countershaft bearing 35 generated by the meshing with the third countershaft reduction gear 38 , V16 is the separation force vector generated by the meshing of the first reduction gear (crankshaft side reduction gear) 36 with the third countershaft reduction gear 38 to the countershaft The load vector of the thrust of the bearing 35 , P17 is the (combined) reaction force (resultant force) vector acting on the intermediate shaft 40 .

According to the above arrangement, V11 to P16 on the intermediate shaft 40 generated when the reduction gears 36 to 39 mesh with each other cancel each other out, and the reaction force (result force) P17 finally acting on the intermediate shaft becomes small. Therefore, the intermediate shaft bearing 35 can be used as the intermediate shaft bearing 35 . By adopting a small bearing (bearing reduced in size in the width direction or in the radial direction) that can support a small load, the drive unit 20 can be reduced in size (eg, the drive unit 20 can be reduced in size in the width direction). 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 (for example, a so-called sports bicycle).

In addition, in this embodiment, as the drive sprocket 13, a sprocket of a shape in which the center side bulges to the right is used, but as the intermediate shaft bearing 35, by using a small bearing, the intermediate shaft bearing 35 or the first The position of the housing 22a holding the intermediate shaft bearing 35 is arranged so as to enter the bulging portion of the drive sprocket 13, and the drive unit 20 can be further reduced in size (for example, the drive unit 20 can be reduced in size in the width direction). As a result, the distance L2 between the crank arms can be made closer to a normal bicycle (for example, a so-called sports bicycle).

In addition, in the drive unit 20 of the electric assist bicycle according to the third embodiment, when the motor shaft (rotating shaft of the electric motor 21) 21a is arranged in front of the crankshaft 7a, the intermediate shaft 40 is arranged in front of the connecting crankshaft 7a. The case where the straight line with the motor shaft 21a is located below is not limited to this. 17 , when the motor shaft 21a is arranged rearward of the crankshaft 7a, the intermediate shaft 40 may be arranged above the straight line connecting the crankshaft 7a and the motor shaft 21a.

In addition, even when the intermediate shaft 40 is arranged on the right side or the left side of the straight line connecting the crankshaft 7a and the motor shaft 21a, etc., it is preferable to view the drive unit 20 from the right side with the drive unit 20 facing the traveling direction. In this state, the intersection angle of the line connecting the axis of the crankshaft 7a and the axis of the intermediate shaft 40 relative to the line connecting the axis of the crankshaft 7a and the axis of the motor shaft 21a is 30° to 30° in the clockwise direction. The crankshaft 7a, the motor shaft 21a, and the intermediate shaft 40 are arranged within 70 degrees.

In addition, as in the drive unit 20 of the electric power-assisted bicycle according to the second embodiment, the same effect can be obtained by applying the same arrangement structure to the drive unit 20 with a built-in speed change mechanism.

Industrial Availability

The present invention is applicable to drive units for various types of electric-assisted bicycles that can travel by applying a power-assisted driving force generated by an electric motor to a human-powered driving force from a pedaling force, and such electric-assisted bicycles.

Claims (11)

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,

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.

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.

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