JP2022066490A - Power-assisted bicycle and driving unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power-assisted bicycle capable of relatively reducing a diameter of a fitted part between a crank shaft 7a and a human power transmission body 28 to which a torque sensor 31 is mounted while the diameter of the connection fitted part of the crank shaft 7a with the crank arm 7b is set to be a size capable of obtaining sufficient connection strength.

SOLUTION: The power-assisted bicycle includes a crank shaft 7a to which human power driving force is transmitted from a pedal through a crank arm 7b and a human power transmission body 28 fitted to an outer periphery of the crank shaft 7a through concave-convex parts 7c, 28b and having a distortion generation unit of a torque sensor 31 formed at the outer periphery. A difference A1 in a radial direction between an outer diameter of a portion fitted with the crank arm 7b and an outer diameter of a portion fitted with the human power transmission body 28 in the crank shaft 7a is smaller than a difference B1 in a radial direction between the concave-convex parts 7c, 28b formed on an inner surface of a portion of the human power transmission body 28 fitted with the crank shaft 7a.

SELECTED DRAWING: Figure 5

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to an electrically assisted bicycle capable of traveling by adding an auxiliary driving force generated by a motor to a human-powered driving force generated by pedaling force from a pedal, and a drive unit attached to the electrically assisted bicycle.

It has a battery as a power source and a drive unit equipped with a motor supplied from this battery, and by adding an auxiliary drive force (assist force) of the drive unit to a human-powered drive force by a pedaling force applied to a pedal. Electric assisted bicycles (also called electric bicycles) that can easily run uphill are already widely known.

In this electrically power assisted bicycle, there is one in which a drive unit having a built-in motor or the like is arranged at a place where a crank shaft is provided. In the electrically assisted bicycle having such an arrangement configuration, the relatively heavy drive unit is arranged at a low position in the center of the electrically assisted bicycle in the front-rear direction (that is, between the front wheels and the rear wheels). Therefore, the electrically power assisted bicycle with this arrangement is easier to lift the front and rear wheels than the motor built in the hub of the front wheels and the hub of the rear wheels, and it is easier even if there is a step in the running path. It has the advantages of good maneuverability of the vehicle body and good running stability, such as being able to overcome the problem.

As described above, a structure in which the drive unit is arranged at the center position in the front-rear direction of the electrically power assisted bicycle is disclosed in, for example, Patent Document 1. As shown in FIG. 21, the drive unit 110 is rotatably supported by bearings 103 and 104 in a posture in which the crank shaft 101 penetrates in the left-right direction. The left and right side portions of the crank shaft 101 project to the left and right from the drive unit 110, and a pedal (not shown) to which a pedaling force is applied is rotatably attached via the crank arm 102.

Inside the drive unit 110, a motor 111 as a drive source, a plurality of pairs of reduction gears 121 to 126 that transmit the driving force from the motor 111 while decelerating (that is, increase the torque from the motor 111), and the like. A deceleration mechanism 120, a torque sensor (human power detection unit) 112 for detecting a human power driving force, and the like are provided. Note that 116 is an intermediate shaft arranged in parallel with the crank shaft 101 and the rotation shaft 111a of the motor 111 inside the drive unit 110. The intermediate shaft 116 is provided with a large-diameter reduction gear 122, a small-diameter reduction gear 123, 124, and the like.

A tubular human-powered transmitter 113 rotates integrally on a part of the outer circumference of the crank shaft 101 (a portion on the left side in FIG. 21) inside the drive unit 110 via a concavo-convex portion 101a such as a spline or serration. It is fitted in the state. Further, a concavo-convex portion 113a such as a spline or serration is also formed at a portion corresponding to the concavo-convex portion 101a of the crank shaft 101 on the inner circumference of the human power transmission body 113. That is, the uneven portion of the human power transmission body 113 meshes with the uneven portion 101a of the crank shaft 101.

Further, a magnetostriction generating portion 112b imparted with magnetic anisotropy is formed on the outer peripheral surface of the human-powered transmitter 113. A coil 112a is arranged on the outer periphery of the magnetostriction generating portion 112b of the human-powered transmitter 113 through a constant gap (space), and the magnetostriction type torque sensor 112 is configured by the magnetostriction generating portion 112b and the coil 112a. Then, the human-powered driving force transmitted from the crank shaft 101 to the human-powered transmission body 113 via the splines (or serrations) 101a and 113a is detected by the torque sensor 112.

Further, in the drive unit 110, an interlocking cylinder 114, a resultant force transmission body 115, or the like is provided with respect to the crank shaft 101 on a part of the outer peripheral side of the crank shaft 101 (the portion on the right side in FIG. 20) inside the drive unit 110. Is rotatably arranged. The resultant force transmission body 115 combines the human power driving force transmitted from the human power transmission body 113 via the interlocking cylinder 114 and the like and the auxiliary driving force transmitted from the motor 111 via the deceleration mechanism 120. Then, the end portion of the resultant force transmission body 115 is projected from the drive unit 110, and the resultant force (driving force in which human-powered driving force and auxiliary driving force are combined) is transmitted from the drive sprocket 105 attached to the protruding portion via the chain 106. Is transmitted to the rear wheel side.

When assembling the drive unit 110, the drive unit 110 is assembled by fitting the human-powered transmission body 113 to which the torque sensor 112 is assembled into the bearing 103 in a state of being fitted to the crank shaft 101. Be done. After that, the crank arm 102 is fitted and attached to the end of the crank shaft 101. Therefore, the diameter of the crank shaft 101 is simply enlarged in FIG. 22 and emphasized in FIG. 22 so that such an assembly work can be performed without any trouble. The diameter d2 of the portion 101c received by the bearing 103 is larger than the diameter (specifically, the diameter of the outer peripheral portion having the maximum diameter) d1, and the portion (spline (or serration) 101a) to which the resultant force transmitter 115 is fitted is. It is formed so that the diameter (specifically, the diameter of the outer peripheral portion having the maximum diameter) d3 of the formed portion) becomes large. That is, the crank shaft 101 is formed in a so-called two-step stepped shape (a shape in which the stepped portion becomes thicker in order).

Further, as described above and as briefly shown in FIG. 23, the spline (or serration) 101a in which the human power transmission body 113 is fitted in the crank shaft 101 has a convex portion 101aa having an outer diameter (mountain portion) and an inward portion. A recessed recess (valley) 101ab is formed. Correspondingly, as simply shown in FIG. 24, the spline (or serration) 113a in which the crank shaft 101 is fitted in the human power transmission body 113 has a convex portion 113aa protruding inward and a concave portion outward. A recess (valley) 113ab is formed.

Then, as shown in FIGS. 23 and 24, the outer diameter of the portion (connecting fitting portion) 101b of the crank shaft 101 where the crank arm 102 is fitted and the portion where the human power transmission body 115 is fitted (spline (or spline)). Serration)) The radial difference (difference from the axis) A from the outer diameter of 101a is the convex portion 113aa on the inner surface of the place (spline (or serration) 113a) where the crank shaft 101 is fitted in the human power transmission body 113. It is formed larger than the radial dimensional difference (so-called height difference) B from the recess 113ab.

International Publication WO2015 / 186159 Gazette

By the way, it may be desired to make such a drive unit 110 smaller and closer to a general bicycle (so-called sports type bicycle or the like). However, the diameter d1 of the connecting fitting portion 101b with the crank arm 102 in the crank shaft 101 must secure a certain dimension and maintain a sufficient strength as the connecting strength at this portion. That is, as shown in FIG. 22, the diameter d2 of the portion 101c received by the bearing 103 is larger than the diameter d1 of the connecting fitting portion 101b of the crank shaft 101 with the crank arm 102, and the resultant force transmitter 115 is further formed. The diameter d3 of the fitted portion (the portion where the spline (or serration) 101a is formed) is gradually thicker in the stepped portion. Further, as shown in FIGS. 23 and 24, the outer diameter of the portion (connecting fitting portion) 101b of the crank shaft 101 where the crank arm 102 is fitted and the portion where the human power transmission body 115 is fitted (spline (or serration)). )) The radial difference A from the outer diameter of 101a is the radial dimensional difference (spline (or serration) 113a) between the convex portion 113aa and the concave portion 113ab at the position (spline (or serration) 113a) in which the crank shaft 101 is fitted in the human power transmission body 113. It is formed larger than the so-called height difference) B. If this structure is adopted, the torque sensor 112 also becomes large correspondingly. Therefore, if the torque sensor 112 and the large-diameter reduction gear 122 assembled to the intermediate shaft 116 are arranged so as not to come into contact with each other, the distance between the crank shaft 101 and the intermediate shaft 116 must be increased to some extent. As a result, there is a problem that the drive unit 110 cannot be miniaturized.

In recent years, as a standard for the bottom bracket (around the crank shaft) of a bicycle, there are standards such as the ISIS standard (International Spline Interface Standard) in which the diameter of the connecting fitting part with the crank arm on the crank shaft is relatively large. There is a tendency for sports-type bicycles that comply with various standards to be preferred. As described above, when the diameter of the connecting fitting portion of the crank shaft with the crank arm is large, the crank shaft has sufficient durability (strength) even when a larger force is applied to the crank shaft, thus improving reliability. However, in this case, the diameter R3 of the crank shaft 101 where the resultant force transmitter 115 is fitted and the torque sensor 112 also become large, so that the crank shaft 101 and the intermediate shaft 116 are further increased. The distance between the shafts and the shaft becomes larger, and the drive unit 110 cannot be miniaturized.

The present invention solves the above-mentioned problems, and human power to attach a torque sensor on the crank shaft while setting the diameter of the connection fitting portion with the crank arm on the crank shaft to a size capable of obtaining sufficient connection strength. It is an object of the present invention to provide an electrically assisted bicycle and a drive unit capable of relatively reducing the diameter of a fitting portion with a transmitter.

In order to solve the above problems, the electrically assisted bicycle of the present invention is an electrically assisted bicycle capable of traveling by adding an auxiliary driving force by a motor to a human-powered driving force by pedaling force from a pedal, and is manually driven by a pedal. It has a crank shaft in which force is transmitted via a crank arm, and a human-powered transmission body in which a strain generating portion of a torque sensor is formed on the outer periphery of the crank shaft, which is fitted to the outer periphery of the crankshaft via a concave-convex portion. A radial difference between the outer diameter of the shaft where the crank arm is fitted and the outer diameter of the place where the human power transmitter is fitted is formed on the inner surface of the place where the crank shaft of the human power transmitter is fitted. It is characterized in that it is smaller than the difference in the radial direction of the uneven portion.

According to this configuration, the difference in the radial direction between the outer diameter of the place where the crank arm is fitted and the outer diameter of the place where the human power transmission body is fitted in the crank shaft is the difference in the radial direction, and the crank shaft of the human power transmission body is fitted. Since it is smaller than the radial difference of the uneven portion formed on the inner surface of the portion, the human-powered transmitter on the crank shaft has a relatively large diameter at the portion where the rank arm is fitted on the crank shaft. The outer diameter of the mated portion can be kept small, and the size (diameter) of the torque sensor can also be kept small.

Further, in the electrically assisted bicycle of the present invention, the outer diameter of the portion where the crank arm is fitted on the crank shaft is larger than the outer diameter of the portion where the human power transmission body is fitted, and the crank shaft of the human power transmission body is formed. It is characterized by being smaller than the diameter of the valleys of splines or serrations formed on the inner surface of the mating site.

According to this configuration, in the fitting portion between the crank shaft and the human power transmission body, the portion having the outer diameter of the portion where the crank arm is fitted in the crank shaft and the corresponding portion in the human power transmission body (opposing each other). It is possible to form a gap (so-called play) with the location). As a result, at the fitting point between the crank shaft and the human power transmission body, the force that tries to bend the crank shaft (that is, the torque detection of the torque sensor) is compared with the case where the crank shaft is fitted without a gap by press fitting or the like. It is possible to reduce the transmission of (forces that may have an adverse effect) to the human-powered transmitter.

Further, in the electrically assisted bicycle of the present invention, the portion of the crank shaft where the crank arm is fitted and the portion where the human-powered transmitter is fitted are located in a radial direction and a mountain portion protruding in the radial direction, respectively. On the other hand, the diameter of the valley, which is the diameter of the portion of the crank shaft where the valley of the crank arm is fitted, is the diameter of the valley where the human-powered transmitter is fitted. It is characterized in that it is equal to or less than the diameter of the valley, which is the diameter of the place where the valley is provided.

Further, in the electrically assisted bicycle of the present invention, the portion of the crank shaft where the crank arm is fitted and the portion where the human power transmitter is fitted are located in the radial direction and the mountain portion protruding in the radial direction, respectively. In each part of the mountain part and the valley part, there is a valley part which is recessed, and between the part where the human power transmission body is fitted in the crank shaft and the place where the crank shaft is fitted in the human power transmission body. , Each has a gap.

According to this configuration, a gap is formed in each portion of the mountain portion and the valley portion between the portion where the human power transmission body is fitted in the crank shaft and the portion where the crank shaft is fitted in the human power transmission body. Can be (have so-called play). As a result, at the fitting point between the crank shaft and the human power transmission body, the force that tries to bend the crank shaft (that is, the torque detection of the torque sensor) is compared with the case where the crank shaft is fitted without a gap by press fitting or the like. It is possible to reduce the transmission of (forces that may have an adverse effect) to the human-powered transmitter.

Further, the electrically assisted bicycle of the present invention is characterized in that splines or serrations are formed at a portion of the crank shaft where the crank arm is fitted and a portion where the human power transmitter is fitted, respectively. ..

Further, in the drive unit of the present invention, the portion of the crank shaft between the portion where the crank arm is fitted and the portion where the human power transmission body is fitted is rotatably supported by a bearing, and the crank shaft has a portion. The difference in the radial direction between the outer diameter of the part supported by the bearing, the outer diameter of the part where the human-powered transmitter is fitted, and the outer diameter of the part where the crank arm is fitted is determined by the crank shaft of the human-powered transmitter. It is characterized in that it is smaller than the difference in the radial direction of the uneven portion formed on the inner surface of the fitted portion. In this case, it is preferable that restricting members for positioning the bearing in the axial direction are fitted on both sides of the crank shaft in the axial direction of the bearing. Further, an oil sealing material may be arranged between the crank shaft and the bearing.

Further, the electrically assisted bicycle of the present invention is characterized in that a drive unit having a motor is provided and a crank shaft is arranged so as to penetrate the drive unit. Further, in this case, it is preferable that an intermediate shaft that rotates at an axis different from the crank shaft is provided, and a reduction gear is attached to the intermediate shaft. According to this configuration, the distance between the crank shaft and the intermediate shaft can be minimized, and the drive unit can be miniaturized.

Further, the drive unit of the present invention is a drive unit provided with the motor, which is attached to an electrically assisted bicycle capable of traveling by adding an auxiliary driving force by a motor to a human-powered driving force by a pedaling force from a pedal. The crank shaft, which is arranged through the unit and transmits the human-powered driving force from the pedal via the crank arm, is fitted to the outer periphery of the crank shaft in the drive unit via a concave-convex portion, and the torque sensor is fitted on the outer periphery. There is a radial difference between the outer diameter of the crank shaft where the crank arm is fitted and the outer diameter of the place where the human power transmitter is fitted. It is characterized in that it is smaller than the difference in the radial direction of the uneven portion formed on the inner surface of the portion where the crank shaft of the human power transmitter is fitted.

According to the present invention, the difference in the radial direction between the outer diameter of the place where the crank arm is fitted and the outer diameter of the place where the human power transmitter is fitted in the crank shaft is such that the crank shaft of the human power transmitter is fitted. By making it smaller than the difference in the radial direction of the uneven portion formed on the inner surface of the portion, even if the diameter of the portion where the crank arm is fitted on the crank shaft is relatively large, human power transmission on the crank shaft is performed. The outer diameter of the place where the body is fitted can be kept small, and the size (diameter) of the torque sensor can also be kept small. Further, when a drive unit equipped with such a torque sensor or a motor is provided, the distance between the crank shaft and the intermediate shaft can be kept small, and the drive unit can be miniaturized. Will be.

Overall left side view of the electrically power assisted bicycle according to the first embodiment of the present invention. A plan sectional view of a drive unit of an electrically power assisted bicycle according to the same embodiment. Simple left side sectional view of the drive unit Enlarged plan view of the main part of the drive unit Enlarged plan view of the main part of the drive unit Left side view of the fitting part of the crank shaft of the same drive unit with the crank arm Side sectional view of the fitting portion of the crank shaft of the drive unit with the human power transmission body. Side sectional view of the fitting portion of the human-powered transmitter of the same drive unit with the crank shaft. Side sectional view of the fitting portion of the human-powered transmitter and the crank shaft of the drive unit. Enlarged side sectional view of the main part of the fitting point of the human power transmission body and the crank shaft of the drive unit. Enlarged side view of the main part of the drive unit in which the fitting points of the human-powered transmitter and the crank shaft are further enlarged. Enlarged plan view of the main part of the modified example of the drive unit of the same embodiment. Side sectional view of the fitting portion of the human-powered transmitter and the crank shaft of the modified example of the drive unit. Enlarged side view of the main part of the fitting part of the human-powered transmitter and the crank shaft of the modified example of the drive unit. An enlarged side sectional view of a main part in which the fitting portion of the human-powered transmitter and the crank shaft of the modified example of the drive unit is further enlarged. A plan sectional view of a drive unit or the like according to another embodiment of the present invention (second embodiment). Overall right side view of the electrically power assisted bicycle according to the third embodiment of the present invention. Right side view of the main part of the electrically power assisted bicycle An exploded perspective view of the hanger and crank unit of the electrically power assisted bicycle Vertical cross-sectional view of the hanger of the electrically power assisted bicycle and the location near the hanger Plane cross-sectional view of the drive unit of a conventional electrically power assisted bicycle Enlarged plan view of the main part of the crank shaft of the conventional electrically power assisted bicycle Enlarged side view of the main part of the crank shaft of the conventional electrically power assisted bicycle Enlarged side view of the main part of the human power transmission body of the conventional electrically power assisted bicycle

Hereinafter, the electrically power assisted bicycle and the drive unit according to the embodiment of the present invention will be described with reference to the drawings. In the following description, the left-right direction and the front-back direction refer to the direction in which the electrically power assisted bicycle is in the traveling direction. Further, the configuration of the present invention is not limited to the configuration described below.

1 in FIG. 1 is an electrically assisted bicycle according to an embodiment of the present invention. As shown in FIG. 1, the electrically assisted 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 standing pipe 2d, a chain stay 2e, a seat stay 2f, and the like. The front wheel 3 rotatably attached to the lower end of the front fork 2b, the rear wheel 4 rotatably attached to the rear end of the chain stay 2e, the handle 5 for changing the direction of the front wheel 3, and the passenger are seated. Includes a saddle 6, a crank 7 and a pedal 8 to which a human-powered driving force consisting of pedaling force is applied, an electric motor 21 (see also FIG. 2) as a driving source for generating an auxiliary driving force (assisting force), and this motor 21. A drive unit 20 provided with a control unit or the like for performing various electrical controls, a battery 12 including a secondary battery for supplying power for driving to the motor 21, and a passenger attached to a handle 5 or the like. The hand-operated unit 18 that can be operated such as, and can switch the power supply of the electrically assisted bicycle 1 and change the setting of the running mode, etc. And, it is attached to the drive sprocket (also called front sprocket, crank sprocket or front gear) 13 as a drive force output wheel body that outputs the resultant force combined with the auxiliary drive force, and the hub (also called rear hub) 9 of the rear wheel 4. As a rear sprocket (sometimes also referred to as a rear gear) 14 as a rear wheel body, and as an endless driving force transmitter wound endlessly over the drive sprocket 13 and the rear sprocket 14 in a rotatable state. It is equipped with a chain 15 and the like.

The electrically assisted bicycle 1 can travel by adding the auxiliary driving force generated by the motor 21 to the human-powered driving force generated by the pedaling force from the pedal 8, and the resultant force obtained by adding the auxiliary driving force to the human-powered driving force drives the bicycle. It is transmitted from the sprocket 13 to the rear wheel 4 via the chain 15 and the rear sprocket 14.

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

As shown in FIG. 1, in the electrically power assisted bicycle 1, the drive unit 20 is arranged at an intermediate position between the front wheels 3 and the rear wheels 4, more specifically, at a position where the crank shaft 7a is penetrated. With such an arrangement, the drive unit 20 having a relatively large weight is arranged at the center of the electrically power assisted bicycle 1 in the front-rear direction. As a result, the front wheels 3 and the rear wheels 4 can be easily lifted, and even if there is a step on the running path, it can be easily overcome. The sex is also good.

As shown in FIG. 2, in the drive unit 20, an outer shell portion and the like are configured by a unit case 22 composed of first to third cases 22a to 22c, and the drive unit 20 (in this embodiment, the rear portion of the drive unit 20). ), The crank shaft 7a penetrates left and right. Further, mounting bolts (not shown) or the like are inserted through a part of the first and second cases 22a and 22b, and the drive unit 20 is placed in the frame 2 (near the lower end portion of the lower pipe 2g or in a standing position). A mounting portion 22d to be attached to a portion near the lower end portion of the pipe 2d, a portion near the front end portion of the chain stay 2e, etc.) is provided. Further, a substantially tubular human power transmission body 28 to which the human power driving force from the crank shaft 7a is transmitted, and an interlocking cylinder 23 to which the human power driving force from the human power transmission body 28 is transmitted to the outer periphery of the crank shaft 7a. The human-powered driving force from the interlocking cylinder 23 is transmitted via a one-way clutch (one-way clutch for cutting the auxiliary driving force) 30, and the resultant force of the human-powered driving force and the auxiliary driving force from the motor 21 is combined. A resultant force transmitter 29 that transmits to the drive sprocket 13 is arranged. Further, the crank shaft 7a, the human power transmission body 28, the interlocking cylinder 23, the resultant force transmission body 29, and the like are arranged coaxially.

Further, in the unit case 22 of the drive unit 20, there is a deceleration mechanism 25 that decelerates the rotation of the motor 21 and transmits it to the resultant force transmission body 29 side (intermediate shaft 40 in this embodiment), and an auxiliary drive force (assist force). ) A motor 21 as a drive source is arranged. In the unit case 22 of the drive unit 20, a board (also referred to as a drive board or a main board) 24 provided with electronic components that perform various electrical controls is also arranged, and is mounted on the board 24 and this board. The control unit is composed of electronic parts and the like. As shown in FIGS. 2 and 3, the axis of the rotating shaft 21a of the motor 21, the axis of the crank shaft 7a, and the axis of the intermediate shaft 40 described later are different from each other. Further, in this embodiment, the rotary shaft 21a, the intermediate shaft 40, and the crank shaft 7a of the motor 21 are arranged in order from the front. However, the present invention is not limited to this, and the rotary shaft 21a, the intermediate shaft 40, and the crank shaft 7a of the motor 21 may be arranged in opposite directions in the front-rear direction.

Further, in the drive unit 20 (specifically, in the unit case 22 of the drive unit 20), a portion excluding both ends of the crank shaft 7a, a human power transmission body 28, an interlocking cylinder body 23, a resultant force transmission body 29, a deceleration mechanism 25, A motor 21, a torque sensor 31, a rotation detector 11, a rotation detector (rotation sensor) 10, and the like, which will be described later, are provided. The human-powered driving force and the auxiliary driving force are combined in the drive unit 20, and the combined combined force is generated from the drive sprocket 13 provided outside the drive unit 20 (specifically, outside the unit case 22 of the drive unit 20). It is output.

The drive unit 20 will be described in more detail. As shown in FIGS. 2 and 3, the crank shaft 7a is rotatably arranged by bearings (crank shaft bearings) 26 and 27 in a state of penetrating the rear portion of the drive unit 20 to the left and right. A cylindrical human-powered transmitter 28 is fitted to the outer periphery of the left side portion of the crank shaft 7a in a state of being integrally rotated with the crank shaft 7a via a spline (or serration) 7c as an uneven portion. A spline (or serration) 28b as an uneven portion is also formed at a portion corresponding to the spline (or serration) 7c of the crank shaft 7a on the inner circumference of the human power transmission body 28, and the spline (or serration) 7c of the crank shaft 7a is formed. Is in mesh with.

On the outer peripheral surface of the human power transmitter 28, a magnetostrictive generation portion 31a imparted with magnetic anisotropy is formed. Further, the coil 31b is arranged on the outer periphery of the magnetostriction generating portion 31a through a constant gap (space). The magnetostrictive generation unit 31a and the coil 31b constitute a magnetostriction type torque sensor (human power detection unit) 31. As a result, the human-powered driving force from the crank shaft 7a is transmitted to the human-powered transmission body 28, and the human-powered driving force is detected by the torque sensor 31. Further, in the magnetostriction type torque sensor 31, the magnetostriction generating portion 31b is formed in a spiral shape having, for example, +45 degrees and −45 degrees with respect to the axial direction of the human power transmitter 28. When the human-powered driving force is transmitted to the human-powered transmission body 28, the magnetostrictive generation portion 31b on the surface of the human-powered transmission body 28 is distorted to generate an increase portion and a decrease portion of the magnetic permeability. It is configured so that the magnitude of torque (human-powered driving force) can be detected by measuring the inductance difference. In the present embodiment, a magnetostrictive torque sensor is used as the torque sensor 31, but a strain-sensing torque sensor in which a strain sensor for detecting the physical strain of the human-powered conductor 28 is arranged on the outer peripheral surface of the human-powered conductor 28 is used. A sensor may be used.

The interlocking cylinder 23 is arranged on the outer periphery of the crank shaft 7a at a position adjacent to the right side of the human power transmission body 28 in a state of being rotatable with respect to the crank shaft 7a. A spline (or serration) 28a formed on the outer periphery of the right end portion of the human power transmission body 28 and a spline (or serration) 23a formed on the inner circumference of the left end portion of the interlocking cylinder 23 are fitted to each other to form the interlocking cylinder 23. Rotates integrally with the human power transmitter 28. In this embodiment, a spline (or serration) 23a formed on the inner circumference of the left end portion of the interlocking cylinder 23 is fitted to the spline (or serration) 28a of the human power transmission body 28 from the outside.

Further, in this embodiment, a rotation detecting body 11 for detecting the rotational state of the interlocking cylinder 23 is attached to the outer periphery of the left side portion of the interlocking cylinder 23. Further, a rotation detector (rotation sensor) 10 as a crank shaft rotation sensor is attached and fixed to the unit case 22 side so that the rotation detector 11 faces from the outer peripheral side. For example, in the rotation detector 10, optical sensors having an emitting unit and a light receiving unit are arranged in the rotation direction of the rotation detector 11 (not shown). The rotation detector 11 has a large number of tooth portions extending to the right in the shape of a comb tooth at a portion on the outer peripheral side thereof. Then, when there is a tooth portion of the rotation detector 11, the emitted light is reflected by the tooth portion and received by the rotation detector 10. As a result, the incident state and non-incident state of light are electrically detected by the light receiving unit of the rotation detector 10, and this signal is input by the control unit to rotate the rotation speed (rotation amount) and rotation of the interlocking cylinder 23. Detect the direction. In addition, instead of the optical sensor, a magnetic sensor such as a Hall IC may be provided to detect the rotation speed (rotation amount) and the rotation direction of the interlocking cylinder 23. Here, the interlocking cylinder 23 rotates integrally with the human power transmission body 28, and the human power transmission body 28 rotates integrally with the crank shaft 7a. As a result, the rotation amount and rotation direction of the interlocking cylinder 23 can be detected, and the rotation speed (rotation amount) and rotation direction of the crank shaft 7a and the pedal 8 can also be detected.

Further, a resultant force transmission body 29 is arranged on the outer periphery of the right side portion of the interlocking cylinder 23 via a one-way clutch (one-way clutch for cutting auxiliary driving force) 30. Then, when the pedal 8 is pedaled to move forward, the human-powered driving force transmitted to the interlocking cylinder 23 is transmitted to the resultant force transmission body 29 via the one-way clutch 30.

The rotary shaft 21a and the rotor 21b of the motor 21 are rotatably supported by the motor shaft bearings 32 and 33. Further, the rotating shaft 21a of the motor 21 is projected to the right side, and a motor shaft reduction gear 39 described later is formed on the outer periphery of the protruding portion.

The reduction gear 25 includes an intermediate shaft 40 arranged in parallel with the crank shaft 7a, and a large-diameter reduction gear (first reduction gear: crank shaft side reduction gear) 36 formed on the left side portion of the resultant force transmission body 29. It has two pairs of reduction gears 36 to 39 including the above, and constitutes a two-stage reduction mechanism. Then, the deceleration mechanism 25 combines the human-powered driving force transmitted through the crank shaft 7a and the auxiliary driving force transmitted from the motor 21, and the resultant force formed by combining the human-powered driving force and the auxiliary driving force. Is transmitted to the resultant force transmitter 29.

The intermediate shaft 40 is arranged so as to extend left and right in the central portion of the drive unit 20 in the front-rear direction and to be rotatably supported by bearings (intermediate shaft bearings) 34 and 35 in a posture parallel to the crank shaft 7a. .. A second intermediate shaft reduction gear 37 having a large diameter, a third intermediate shaft reduction gear 38 having a small diameter, and a one-way clutch 42 for cutting a human-powered driving force are attached to the intermediate shaft 40.

The one-way clutch 42 for cutting the human-powered driving force is arranged between the outer circumference of the intermediate shaft 40 and the inner circumference of the second intermediate shaft reduction gear 37 to cut off the human-powered driving force from the pedal 8. belongs to. That is, when the motor 21 is not driven by the one-way clutch 42 and the auxiliary driving force is not generated, the human-powered driving force from the pedal 8 is disengaged by the one-way clutch 42 for cutting the human-powered driving force. Therefore, it is not necessary to rotate the rotor 21b of the motor 21. On the other hand, when the 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 are connected. 37 and 38 rotate integrally with the intermediate shaft 40.

Then, 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, the motor 21 is rotated and an auxiliary driving force is output. In this case, the rotation of the motor 21 is decelerated, and the torque of the auxiliary driving force from the motor 21 is amplified and transmitted to the intermediate shaft 40 side. Further, since the small diameter third intermediate shaft 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 auxiliary driving force transmitted to the intermediate shaft 40 Is further amplified and transmitted to the first reduction gear 36. Then, in the resultant force transmission body 29 in which the first reduction gear 36 is integrally formed, the human-powered driving force and the auxiliary driving force from the motor 21 are combined and output from the driving sprocket 13 as the driving force output wheel body. To.

Here, as shown in an enlarged manner in FIGS. 4 to 10, the outer diameter (specifically, the diameter of the outer peripheral portion) D1 of the crank shaft 7a where the crank arm 7b is fitted and the human-powered transmitter 28 are fitted. A radial difference (difference in radial dimension from the axis X of the crank shaft 7a) A1 with the outer diameter D2 of the fitted portion is formed on the inner surface of the portion where the crank arm 7b of the human power transmission body 28 is fitted. It is made smaller than the radial difference (so-called height difference of the uneven portion) B1 of the spline (or serration) 28b as the uneven portion. Further, in this embodiment, a spline (or serration) 7d as an uneven portion is also formed at a position where the crank arm 7b of the crank shaft 7a is fitted, and correspondingly, the crank shaft of the crank arm 7b is formed. A spline (or serration) 7e as an uneven portion is also formed at the fitting portion of the 7a.

That is, the portion where the human power transmission body 28 in the crank shaft 7a is fitted and the portion where the crank shaft 7a in the human power transmission body 28 is fitted correspondingly are peaks protruding in the radial direction, respectively. Splines (or serrations) 7c and 28b are formed as uneven portions having a portion and a valley portion recessed in the radial direction. Further, in the place where the human power transmission body 28 is fitted in the crank shaft 7a and the place where the crank shaft 7a in the crank arm 7b is fitted, there are mountain portions protruding in the radial direction and a radial portion in the radial direction, respectively. On the other hand, splines (or serrations) 7d and 7e are formed as uneven portions in which recessed valley portions are provided at predetermined angles. Further, the outer diameter D1, which is the diameter of the portion of the crank shaft 7a where the mountain portion of the spline (or serration) 7d fitted to the crank arm 7b is provided, is a spline fitted to the human-powered transmitter 28 of the crank shaft 7a. (Or serration) On the inner surface of the portion (spline (or serration) 7d) where the crank shaft 7a of the human power transmitter 27 is fitted, which is larger than the outer diameter D2 which is the diameter of the portion where the peak portion of 7c is provided. It is formed smaller than the formed inner diameter (diameter between the splines of the human power transmitter 27 or the valley of the serration 7d). Then, as described above, the radial difference between the outer diameter D1 of the place where the crank arm 7b is fitted and the outer diameter D2 of the place where the human power transmission body 28 is fitted (from the axial center X of the crank shaft 7a). Radial difference) A1 is the radial difference of the spline (or serration) 28b as the uneven portion formed on the inner surface of the place where the crank arm 7b of the human power transmission body 28 is fitted (the height of the so-called uneven portion). Difference) It is smaller than B1.

Further, as shown in an enlarged scale in FIG. 11, a mountain portion is formed between the portion where the human power transmission body 28 in the crank shaft 7a is fitted and the portion where the crank shaft 7a in the human power transmission body 28 is fitted. And each part of the valley part is formed so as to have a gap (so-called play). The preferred size of this gap is m (module) = d (reference circle diameter) / at the location where the splines (or serrations) 7c and 28b, which are the fitting portions of the crank shaft 7a and the human power transmission body 28, are provided. When indicated by z (number of teeth), the gap E between the mountain portion of the crank shaft 7a and the corresponding portion of the human power transmission body 28 is 0 to 0.25 m (for example, 0.001 m larger than 0). The above) and 0.25 m or less) are suitable. Further, the gap F between the valley portion of the crank shaft 7a and the corresponding portion of the human power transmission body 28 is 0 to 0.1 m (greater than 0 (for example, 0.001 m or more), 0.1 m or less). Suitable. The height (radial dimension) of the spline (or serration) 7c where the human power transmission body 28 is fitted in the crank shaft 7a is set to, for example, 2.25 m, but the height is not limited to this.

Further, the spline (or serration) 7c formed at the portion of the crank shaft 7a where the human-powered transmitter 28 is fitted is extended to the portion where the human-powered transmitter 28 is fitted with the bearing 26. That is, the portion of the crank shaft 7a between the place where the human power transmission body 28 is fitted (spline (or serration) 7c) and the place where the crank arm 7b is fitted (spline (or serration) 7d) is a bearing. It is rotatably supported by (bearing arranged on the left side in this embodiment) 26. Then, the outer diameter D3 of the portion of the crank shaft 7a supported by the bearing 26, the outer diameter D2 of the portion (spline (or serration)) to which the human power transmission body 28 is fitted, and the crank arm 7b are fitted. The crank arm 7b of the human-powered transmitter 28 is fitted with a radial difference (difference in radial dimension from the axial center X of the crank shaft 7a) with the outer diameter D1 of the location (spline (or serration) 7d). The difference in the radial direction (so-called height difference of the uneven portion) B1 of the spline (or serration) 28b as the uneven portion formed on the inner surface of the portion is made smaller. In this embodiment, the outer diameter D3 of the portion of the crank shaft 7a supported by the bearing 26 is the same as the outer diameter D2 of the portion (spline (or serration) 7c) to which the human power transmission body 28 is fitted. However, it is not limited to this.

However, as shown in FIGS. 9 and 10, the diameter (valley diameter) T1 of the portion of the crank shaft 7a where the valley portion where the crank arm 7b is fitted is provided is the human power transmission in the crank shaft 7a. It is smaller than the diameter (valley diameter) T2 of the portion where the valley portion of the portion where the body 28 is fitted is provided. In this way, the diameter (valley diameter) T1 of the portion of the crank shaft 7a where the crank arm 7b is fitted is provided, and the portion of the crank shaft 7a where the human-powered transmitter 28 is fitted. When the diameter (valley diameter) of the portion where the valley portion is provided is T2 or less, it is easy to process the valley portion on the crank shaft. Further, in this embodiment, the number of ridges and valleys of the crank shaft 7a where the human-powered transmitter 28 is fitted is the same as the number of ridges and valleys of the crank shaft 7a where the crank arm 7b is fitted. The number of parts is doubled, and the mountain part of the crank shaft 7a where the crank arm 7b is fitted is the mountain part of the crank shaft 7a where the human power transmitter 28 is fitted. It is formed to correspond to. That is, in this embodiment, every other mountain portion of the crank shaft 7a where the crank arm 7b is fitted is every other mountain portion of the crank shaft 7a where the human power transmission body 28 is fitted. (That is, adjacent peaks are formed at double angles in the circumferential direction).

Further, as shown in FIGS. 4 and 5, in this embodiment, splines (splines (or serrations) 7c) peaks are formed on both sides (left side and right side) of the bearing 26 in the crank shaft 7a in the axial direction. The outer peripheral side portion is shaved to form a groove portion 7f, and a regulating member 43 for positioning the bearing 26 so as not to move in the axial direction (that is, in the left-right direction) is fitted in each of the groove portions 7f. It has been combined. Also, in the axial direction (that is, in the left-right direction), at the intermediate point between both regulating members 43, in the circumferential direction at the same depth as the valley portion of the spline (spline (or serration) 7c). A groove portion 7g is formed, and an oil sealing material 44 that seals between the crank shaft 7a and the human power transmission body 28 in the radial direction is arranged in the groove portion 7g. The oil sealing material 44 can prevent water and mud from entering the inside of the unit case 22 from the outside. Further, the lubricating oil applied to the reduction gears 36 to 39 and the like is prevented from leaking from the inside of the drive unit 20 to the outside of the drive unit 20 through the gap between the crank shaft 7a and the human power transmission body 28. It has become.

In this embodiment, a flange-shaped portion 7i projecting to the inner peripheral side is integrally formed adjacent to the spline (or serration) 7d that fits with the spline (or serration) 7d of the crank shaft 7a in the crank arm 7b. Has been done. When assembling the crank arm 7b to the crank shaft 7a, the flange-shaped portion 7i of the crank arm 7b is fitted to the crank shaft 7a from the side until it abuts from the side, and then the fixing member 45 is attached from the outside of the crank arm 7b. The male screw portion 45a is screwed into the female screw portion 7h formed on the inner circumference of the end portion of the crank shaft 7a, and the crank arm 7b is fixed so as not to come off. The 46 is a washer sandwiched between the crank arm 7b and the fixing member 45, and may be provided as needed.

According to the above configuration, in the crank shaft 7a, the outer diameter D1 of the place where the crank arm 7b is fitted (spline (or serration) 7d) and the place where the human power transmission body 28 is fitted (spline (or serration) 7c). ) The difference A1 in the radial direction from the outer diameter D2 is larger than the difference in the radial direction B1 of the spline (or serration) 7c as the uneven portion formed on the inner surface of the portion where the crank shaft 7a of the human power transmitter 28 is fitted. small. Further, in the present embodiment, the outer diameter D3 of the portion of the crank shaft 7a supported by the bearing 26 is also the outer diameter D2 of the portion (spline (or serration) 7c) to which the human power transmission body 28 is fitted. It is the same. Therefore, even when the diameter (outer diameter) of the portion (spline (or serration) 7d) where the crank arm 7b is fitted in the crank shaft 7a is relatively large, the human-powered transmitter 28 in the crank shaft 7a is fitted. The outer diameter D2 of the location (spline (or serration) 7c) can be kept small, and the size (diameter) of the torque sensor 31 can also be kept small. As a result, the distance between the crank shaft 7a and the intermediate shaft 40 can be kept small, and the drive unit 20 can be miniaturized.

In the crank shaft 7a, the outer diameter D1 of the place where the crank arm 7b is fitted (spline (or serration) 7d) and the outer diameter of the place where the human power transmitter 28 is fitted (spline (or serration) 7c). The radial difference A1 from D2 is within 90% of the radial difference B1 of the spline (or serration) 28b as an uneven portion formed on the inner surface of the portion where the crank shaft 7a of the human power transmission body 28 is fitted. It is preferable, and more preferably 50% or less is more preferable.

Further, in the above embodiment, the outer diameter D3 of the portion of the crank shaft 7a supported by the bearing 26 and the outer diameter D2 of the portion (spline (or serration)) where the human power transmission body 28 is fitted and the crank arm 7b. Radial difference A1 from the outer diameter D1 of the place where is fitted is the radial direction of the spline (or serration) 28b as an uneven portion formed on the inner surface of the place where the crank shaft 7a of the human power transmission body 28 is fitted. The difference is smaller than B1. Also by this, even when the diameter (outer diameter) of the portion (spline (or serration) 7d) where the crank arm 7b is fitted in the crank shaft 7a is relatively large, it is supported by the bearing 26 in the crank shaft 7a. The outer diameter D3 of the bearing portion and the outer diameter D2 of the portion where the human power transmission body 28 is fitted (spline (or serration) 7c) in the crank shaft 7a can be suppressed to a small size, and the size (diameter) of the torque sensor 31 can be suppressed. ) Can also be kept small. As a result, the distance between the crank shaft 7a and the intermediate shaft 40 can be kept small, and the drive unit 20 can be miniaturized.

In recent years, as a standard for the bottom bracket (around the crank shaft) of a bicycle, there are standards such as the ISIS standard (International Spline Interface Standard) in which the diameter of the connecting fitting part with the crank arm on the crank shaft is relatively large. In order to comply with various standards, the diameter of the connecting fitting portion of the crank shaft 7a with the crank arm 7b is made relatively large, and sufficient durability (strength) is sufficient even if a larger force is applied from the crank arm 7b to the crank shaft 7a. ), As described above, the outer diameter D2 of the crank shaft 7a where the human power transmission body 28 is fitted (spline (or serration) 7c) can be suppressed to a small size, and the torque can be suppressed. The size (diameter) of the sensor 31 can be kept small, and the drive unit 20 can be miniaturized.

Further, according to the above configuration, a place where the human power transmission body 28 in the crank shaft 7a is fitted (spline (or serration) 7c) and a place where the crank shaft 7a in the human power transmission body 28 is fitted (spline (or serration) 7c). Gap E and F are formed in each of the mountain portion and the valley portion between the serration) 28b). As a result, at the fitting portion between the crank shaft 7a and the human power transmission body 28, a force for bending the crank shaft 7a (that is, a torque sensor 31) as compared with the case where the crank shaft 7a is fitted without a gap by press fitting or the like. It is possible to reduce the transmission of the force (a force that may adversely affect the torque detection) to the human power transmission body 28.

That is, when the pedal 8 is stepped on, a force for bending the crank shaft 7a in a direction orthogonal to the axis X acts in addition to a force for twisting the crank shaft 7a in the axis rotation direction. Without the gaps E and F, the force for bending the crank shaft 7a is directly transmitted to the magnetostriction generating portion 31a of the torque sensor 31 via the human power transmission body 28. The force that tries to bend the crank shaft 7a becomes noise when detecting the torque (force that twists in the shaft rotation direction) of the torque sensor 31, which adversely affects the detection accuracy of the torque sensor 31.

On the other hand, a place where the human power transmission body 28 in the crank shaft 7a is fitted (spline (or serration) 7c) and a place where the crank shaft 7a in the human power transmission body 28 is fitted (spline (or serration) 28b). ), By providing the gaps E and F, the force for bending the crank shaft 7a is reduced to be transmitted to the human power transmission body 28, and the detection accuracy of the torque sensor 31 is less likely to decrease. As a result, the reliability of the electric bicycle 1 can be improved.

Further, according to the above configuration, the number of peaks and valleys where the human-powered transmitter 28 is fitted on the crank shaft 7a is the number of peaks and valleys where the crank arm 7b is fitted on the crank shaft 7a. The number of parts is doubled, and the part that becomes the mountain part of the crank shaft 7a where the crank arm 7b is fitted is the mountain part of the crank shaft 7a where the human power transmitter 28 is fitted. The human-powered driving force (treading force) acting on the crank shaft 7a is transmitted to the human-powered transmitter 28 through the spline (or serration) 7c in which many peaks and valleys are formed. Therefore, the torque can be detected with good sensitivity by the torque sensor 31 in which the magnetic strain generating portion 31b is formed on the outer periphery of the human power transmission body 28. That is, the shape of the spline (or serration) 7c where the human power transmission body 28 on the crank shaft 7a is fitted is the shape of the spline (or serration) 7d where the crank arm 7b on the crank shaft 7a is fitted. Even when the shape is the same, it is possible to fit the human power transmission body 28 to the crank shaft 7a, but the peaks and valleys of the parts of the crank shaft 7a where the human power transmission body 28 is fitted are If the number is larger, the torque can be detected with good sensitivity (accuracy), and the reliability is improved.

Further, by making the number of peaks of the fitting portion of the human power transmission body 28 and the fitting portion of the crank arm 7b on the crank shaft 7a different from each other, or by making the diameter of the valley portion different, the crank arm 7b It is also possible to perform assembly by restricting the position of the crank shaft 7a in the axial direction (left-right direction in this embodiment).

Further, according to the above configuration, by providing the oil sealing material 44 that seals between the crank shaft 7a and the human power transmission body 28 in the radial direction, the lubricating oil applied to the reduction gears 36 to 39 and the like can be removed. It is possible to satisfactorily prevent leakage from the inside of the drive unit 20 to the outside of the drive unit 20 through the gap between the crank shaft 7a and the human power transmission body 28.

Further, in the above embodiment, the outer diameter D1, which is the diameter of the portion of the crank shaft 7a where the mountain portion of the spline (or serration) 7d fitted to the crank arm 7b is provided, is the human power transmission body in the crank shaft 7a. The case where the outer diameter D2, which is the diameter of the portion where the mountain portion of the spline (or serration) 7c to be fitted to 28 is provided, is formed larger than the outer diameter D2 has been described, but the present invention is not limited to this. That is, the outer diameter D1, which is the diameter of the portion of the crank shaft 7a where the mountain portion of the spline (or serration) 7d fitted to the crank arm 7b is provided, is the spline fitted to the human-powered transmitter 28 of the crank shaft 7a. (Or serration) It may be formed smaller than the outer diameter D2, which is the diameter of the portion where the peak portion of 7c is provided.

Further, as shown in FIGS. 12 to 15, the outer diameter D1 (specifically, the diameter of the outer peripheral portion) of the crank shaft 7a where the crank arm 7b is fitted is fitted with the human power transmission body 28. The outer diameter D2 of the portion may be the same as the dimension (a modification of the first embodiment). That is, the outer diameter D1 which is the diameter of the portion of the crank shaft 7a where the mountain portion of the spline (or serration) 7d fitted to the crank arm 7b is provided, and the spline fitted to the human-powered transmitter 28 on the crank shaft 7a. (Or serration) The outer diameter D2, which is the diameter of the portion where the peak portion of 7c is provided, has the same dimensions.

Further, the portion of the crank shaft 7a between the place where the human power transmission body 28 is fitted (spline (or serration) 7c) and the place where the crank arm 7b is fitted (spline (or serration) 7d) is a bearing. Although it is rotatably supported by (the bearing arranged on the left side in this embodiment) 26, the human power transmission body 28 is also fitted to the outer diameter D3 of the portion supported by the bearing 26 in the crank shaft 7a. It is the same as the outer diameter D2 of the place where the crank arm 7b is fitted (spline (or serration) 7c) and the outer diameter D1 of the place where the crank arm 7b is fitted (spline (or serration) 7d).

According to the above configuration, the outer diameter D1 of the crank shaft 7a where the crank arm 7b is fitted (spline (or serration) 7d) and the location where the human power transmitter 28 is fitted (spline (or serration)). 7c) is the same as the outer diameter D2 (in the present embodiment, the outer diameter D3 of the portion supported by the bearing 26 in the crank shaft 7a is also the same). Therefore, even when the diameter (outer diameter) of the portion (spline (or serration) 7d) where the crank arm 7b is fitted in the crank shaft 7a is relatively large, the human-powered transmitter 28 in the crank shaft 7a is fitted. The outer diameter D2 of the location (spline (or serration) 7c) can be minimized, and the size (diameter) of the torque sensor 31 can also be minimized. As a result, the distance between the crank shaft 7a and the intermediate shaft 40 can be minimized, and the drive unit 20 can be miniaturized.

Further, in the above embodiment, the human-powered driving force and the auxiliary driving force are combined in the drive unit 20, and the combined resultant force is outside the drive unit 20 (specifically, outside the unit case 22 of the drive unit 20). Although the case of the configuration (so-called uniaxial drive unit 20) output from the drive sprocket 13 provided in the above is described, the present invention is not limited to this.

As shown in FIG. 16, in this embodiment, the auxiliary driving force from the motor 21 is rotatably supported in a state of being exposed to the outside of the drive unit 20'via the reduction gear 37 of the reduction mechanism 25 and the like. It is output to the auxiliary sprocket 61. That is, it is a so-called biaxial drive unit 20'. Then, only the human-powered driving force input to the pedal 8 is output from the drive sprocket 13 that is rotatable at the coaxial center with the crank shaft 7a, and the chain 15 as the driving force transmitting means assists the human-powered driving force and the motor 21. The driving force is combined and output to the rear wheel 4 side. In the embodiment shown in FIG. 15, a drive sprocket 13 that outputs a human-powered driving force is attached to the auxiliary interlocking cylinder 23B in which the rotation of the interlocking cylinder 23A is transmitted via the one-way clutch.

Also in this embodiment, the configuration of the fitting portion of the crank shaft 7a and the driving force transmission body 28 provided with the torque sensor, and the configuration of the fitting portion of the crank shaft 7a and the crank arm 7b are the above-described embodiments. Is similar to. The same reference numerals are given to the members having the same operation as that of the above embodiment.

Further, as in the above embodiment, also in this embodiment (second embodiment), as shown in FIGS. 16 and 6 to 11, the crank arm 7b in the crank shaft 7a is fitted. Radial difference between the outer diameter (specifically, the diameter of the outer peripheral portion) D1 and the outer diameter D2 of the place where the human power transmitter 28 is fitted (difference in radial dimension from the axial center X of the crank shaft 7a). ) A1 is larger than the radial difference (so-called height difference of the uneven portion) B1 of the spline (or serration) 28b as the uneven portion formed on the inner surface of the portion where the crank arm 7b of the human power transmission body 28 is fitted. It has been made smaller. Further, a spline (or serration) 7d as an uneven portion is also formed at a portion of the crank shaft 7a where the crank arm 7b is fitted, and correspondingly, a spline (or serration) 7d is formed at the fitting portion of the crank shaft 7a of the crank arm 7b. A spline (or serration) 7e is formed as an uneven portion.

That is, the portion where the human power transmission body 28 in the crank shaft 7a is fitted and the portion where the crank shaft 7a in the human power transmission body 28 is fitted correspondingly are peaks protruding in the radial direction, respectively. Splines (or serrations) 7c and 28b are formed as uneven portions having a portion and a valley portion recessed in the radial direction. Further, in the place where the human power transmission body 28 is fitted in the crank shaft 7a and the place where the crank shaft 7a in the crank arm 7b is fitted, there are mountain portions protruding in the radial direction and a radial portion in the radial direction, respectively. On the other hand, splines (or serrations) 7d and 7e are formed as uneven portions in which recessed valley portions are provided at predetermined angles. Further, in this embodiment, the outer diameter D1, which is the diameter of the portion of the crank shaft 7a where the mountain portion of the spline (or serration) 7d fitted to the crank arm 7b is provided, is a human-powered transmitter in the crank shaft 7a. A location (spline (or serration)) where the crank shaft 7a of the human-powered transmitter 27 is fitted, which is larger than the outer diameter D2, which is the diameter of the portion of the spline (or serration) 7c that fits 28. ) 7d) is formed smaller than the inner diameter (diameter between the splines of the human power transmitter 27 or the valley of the serration 7d) formed on the inner surface. Further, the connecting structure of the other crank shaft 7a, the human power transmission body 28, the torque sensor 31, and the crank arm is the same as that of the first embodiment and the second embodiment described above.

Further, as shown in an enlarged scale in FIG. 15, a mountain portion is formed between the portion where the human power transmission body 28 in the crank shaft 7a is fitted and the portion where the crank shaft 7a in the human power transmission body 28 is fitted. And each part of the valley part is formed so as to have a gap (so-called play).

That is, even in this configuration, the outer diameter D1 of the crank shaft 7a where the crank arm 7b is fitted (spline (or serration) 7d) and the human-powered transmitter 28 are fitted (spline (or serration)). The difference in the radial direction from the outer diameter D2 of 7c) is from the difference in the radial direction of (spline (or serration) 7c) as the uneven portion formed on the inner surface of the portion where the crank shaft 7a of the human power transmitter 28 is fitted. Is also small. With this configuration, even when the diameter (outer diameter) of the portion (spline (or serration) 7d) where the crank arm 7b is fitted in the crank shaft 7a is relatively large, the human power transmission body 28 in the crank shaft 7a can be used. The outer diameter D2 of the mated portion (spline (or serration) 7c) can be kept small, and the size (diameter) of the torque sensor 31 can also be kept small. As a result, the distance between the crank shaft 7a and the intermediate shaft 40 can be kept small, and the drive unit 20 can be miniaturized.

In the first and second embodiments, the case where the crank shaft 7a has a structure that penetrates the inside of the drive unit 20 provided with the motor 21 that generates the auxiliary driving force has been described, but the present invention is limited to this. It's not a thing.

17 to 20 show the electrically power assisted bicycle 50 according to the third embodiment of the present invention. As shown in FIG. 17, in the electrically power assisted bicycle 50 of this embodiment, the electric motor 21 is a front wheel. It is arranged inside the hub (also referred to as a front hub) 16 of 3. Further, although the control unit (not shown) is arranged near the mounting portion of the battery 12, the control unit may be arranged at another location such as the hand operation unit. The electric motor 10 may be disposed inside the hub (rear hub) of the rear wheel 4 instead of being disposed inside the front hub 16. The same components as those of the electrically power assisted bicycle 1 according to the first embodiment are designated by the same reference numerals.

In this embodiment, the drive unit that generates the auxiliary driving force is provided inside the front hub 16 (or the rear hub), and the auxiliary driving force is applied from the front hub 16 of the front wheel 3 or the rear hub of the rear wheel 4. It is supposed to be done. On the other hand, the structure of the torque sensor 31 itself that detects the human-powered driving force due to the pedaling force is the same as that of the above-described embodiment.

As briefly shown in FIG. 18, in this embodiment, the rear end portion of the lower pipe 2g, the lower end portion of the vertical pipe 2d, and the front end portion of the chain stay 2e are arranged in a state of being connected by a hanger 2h. Has been done. Then, as shown in FIGS. 19 and 20, the crank shaft 7a is rotatably arranged inside the hanger 2h via the bearings 26 and 27, and the torque sensor 31 detects the force corresponding to the pedaling force. Are arranged. Note that, in FIG. 9, regarding the drive sprocket 13, only the portion of the drive sprocket 13, which is also referred to as a spider, that supports the gear portion 13a is shown.

As shown in FIG. 20, in this embodiment, a metal middle cylinder 51 is arranged inside the hanger 2h, and a crank shaft 7a and the like are provided via bearings 26 and 27 provided inside the middle cylinder 51. It is rotatably supported. On the outer periphery of the crank shaft 7a, a cylindrical human-powered transmission body 28, an interlocking cylinder 23 interlocking with the drive sprocket 13, and the like are arranged. Reference numeral 52 in FIGS. 19 and 20 is a fixed cylinder that is fitted and fixed from the left side with the middle cylinder or the like inserted in the hanger 2h.

As shown in FIG. 20, similarly to the above embodiment, the crank shaft 17 is a spline (or serration) in which a human power transmission body 28 for transmitting human power driving force is fitted from the outer periphery in an intermediate portion in the axial direction. 7c is formed, and correspondingly, a spline (or serration) 28b that fits into the spline (or serration) 7c of the crank shaft 17 is also formed on the inner circumference of the left side portion of the human power transmission body 28. There is. Further, the human power transmission body 28 and the interlocking cylinder 23 are configured to be integrally interlocked with each other via the spline (or serration) 23a and 28a, and further, the interlocking cylinder 23 and the drive sprocket 13 are both splined (or serration) 23b. , 13b are configured to be integrally interlocked with each other, whereby the rotational driving force (human power driving force) of the crank shaft 7a is transmitted to the drive sprocket 13 via the human power transmission body 28 and the interlocking cylinder 23. Further, it is configured to be transmitted to the rear wheel 4 side via the chain 15. The interlocking cylinder 23 is rotatably arranged on the outer periphery of the crank shaft 7a, and the interlocking cylinder 23 and the crank shaft 7a are rotatably arranged by the bearing 27 assembled on the outer periphery of the interlocking cylinder 23. It is supported.

Also in the above configuration, the outer diameter D1 of the crank shaft 7a where the crank arm 7b is fitted (spline (or serration) 7d) and the location where the human power transmitter 28 is fitted (spline (or serration) 7c)). Radial difference from the outer diameter D2 (difference in radial dimension from the axis X of the crank shaft 7a) A1 is an uneven portion formed on the inner surface of the portion where the crank arm 7b of the human power transmission body 28 is fitted. The radial difference is smaller than the radial difference (so-called height difference of the uneven portion) B1 of the uneven portion formed on the inner surface of the portion where the crank shaft 7a of the human power transmission body 28 is fitted (so-called uneven portion height difference). (See FIGS. 9 to 11 and the like). Therefore, even when the diameter (outer diameter) of the portion (spline (or serration) 7d) where the crank arm 7b is fitted in the crank shaft 7a is relatively large, the human-powered transmitter 28 in the crank shaft 7a is fitted. The outer diameter D2 of the location (spline (or serration) 7c) can be kept small, and the size (diameter) of the torque sensor 31 can also be kept small. As a result, the crank shaft 7a and the torque sensor 31 can be arranged in the hanger 2h without any trouble without increasing the diameter of the hanger 2h.

In recent years, as a standard for the bottom bracket (around the crank shaft) of a bicycle, there are standards such as the ISIS standard (International Spline Interface Standard) in which the diameter of the connecting fitting part with the crank arm on the crank shaft is relatively large. In order to comply with various standards, the diameter of the connecting fitting portion of the crank shaft 7a with the crank arm 7b is made relatively large, and sufficient durability (strength) is sufficient even if a larger force is applied from the crank arm 7b to the crank shaft 7a. ), As described above, the outer diameter D2 of the crank shaft 7a where the human power transmission body 28 is fitted (spline (or serration) 7c) can be suppressed to a small size, and the torque can be suppressed. The size (diameter) of the sensor 31 can also be kept small, and the crank shaft 7a and the torque sensor 31 can be arranged in the hanger 2h without any trouble.

Further, according to the above configuration, the number of peaks and valleys where the human-powered transmitter 28 is fitted on the crank shaft 7a is the number of peaks and valleys where the crank arm 7b is fitted on the crank shaft 7a. The number of parts is doubled, and the part that becomes the mountain part of the crank shaft 7a where the crank arm 7b is fitted is the mountain part of the crank shaft 7a where the human power transmitter 28 is fitted. The human-powered driving force (treading force) acting on the crank shaft 7a is transmitted to the human-powered transmitter 28 through the spline (or serration) 7c in which many peaks and valleys are formed. Therefore, the torque can be detected with good sensitivity by the torque sensor 31 in which the magnetic strain generating portion 31b is formed on the outer periphery of the human power transmission body 28. That is, the shape of the spline (or serration) 7c where the human power transmission body 28 on the crank shaft 7a is fitted is the shape of the spline (or serration) 7d where the crank arm 7b on the crank shaft 7a is fitted. Even when the shape is the same, it is possible to fit the human power transmission body 28 to the crank shaft 7a, but the peaks and valleys of the parts of the crank shaft 7a where the human power transmission body 28 is fitted are If the number is larger, the torque can be detected with good sensitivity (accuracy), and the reliability is improved.

Further, by making the number of peaks of the fitting portion of the human power transmission body 28 and the fitting portion of the crank arm 7b on the crank shaft 7a different from each other, or by making the diameter of the valley portion different, the crank arm 7b It is also possible to perform assembly by restricting the position of the crank shaft 7a in the axial direction (left-right direction in this embodiment).

The present invention is applicable to various electrically assisted bicycles capable of traveling by adding an auxiliary driving force generated by a motor to a human-powered driving force generated by pedaling force from a pedal, and various drive units attached to the electrically assisted bicycle. ..

1 Electric assist bicycle 2 Frame 3 Front wheel 4 Rear wheel 5 Handle 7 Crank 7a Crank shaft 7b Crank arm 7c, 7d Spline (or serration) (uneven part)
8 Pedal 12 Battery (capacitor)
13 Drive sprocket (driving force output wheel)
14 Rear sprocket 15 Chain (endless driving force transmitter)
20 Drive unit 21 Motor 23 Interlocking cylinder 28 Human-powered transmitter 28b Spline (or serration) (concavo-convex part)
40 Intermediate axis

The present invention relates to an electrically assisted bicycle capable of traveling by adding an auxiliary driving force generated by a motor to a human-powered driving force generated by pedaling force from a pedal, and a drive unit attached to the electrically assisted bicycle.

It has a battery as a power source and a drive unit equipped with a motor supplied from this battery, and by adding an auxiliary drive force (assist force) of the drive unit to a human-powered drive force by a pedaling force applied to a pedal. Electric assisted bicycles (also called electric bicycles) that can easily run uphill are already widely known.

In this electrically power assisted bicycle, there is one in which a drive unit having a built-in motor or the like is arranged at a place where a crank shaft is provided. In the electrically assisted bicycle having such an arrangement configuration, the relatively heavy drive unit is arranged at a low position in the center of the electrically assisted bicycle in the front-rear direction (that is, between the front wheels and the rear wheels). Therefore, the electrically power assisted bicycle with this arrangement is easier to lift the front and rear wheels than the motor built in the hub of the front wheels and the hub of the rear wheels, and it is easier even if there is a step in the running path. It has the advantages of good maneuverability of the vehicle body and good running stability.

As described above, a structure in which the drive unit is arranged at the center position in the front-rear direction of the electrically power assisted bicycle is disclosed in, for example, Patent Document 1. As shown in FIG. 21, the drive unit 110 is rotatably supported by bearings 103 and 104 in a posture in which the crank shaft 101 penetrates in the left-right direction. The left and right side portions of the crank shaft 101 project to the left and right from the drive unit 110, and a pedal (not shown) to which a pedaling force is applied is rotatably attached via the crank arm 102.

Inside the drive unit 110, a motor 111 as a drive source, a plurality of pairs of reduction gears 121 to 126 that transmit the driving force from the motor 111 while decelerating (that is, increase the torque from the motor 111), and the like. A deceleration mechanism 120, a torque sensor (human power detection unit) 112 for detecting a human power driving force, and the like are provided. Note that 116 is an intermediate shaft arranged in parallel with the crank shaft 101 and the rotation shaft 111a of the motor 111 inside the drive unit 110. The intermediate shaft 116 is provided with a large-diameter reduction gear 122, a small-diameter reduction gear 123, 124, and the like.

A tubular human-powered transmitter 113 rotates integrally on a part of the outer circumference of the crank shaft 101 (a portion on the left side in FIG. 21) inside the drive unit 110 via a concavo-convex portion 101a such as a spline or serration. It is fitted in the state. Further, a concavo-convex portion 113a such as a spline or serration is also formed at a portion corresponding to the concavo-convex portion 101a of the crank shaft 101 on the inner circumference of the human power transmission body 113. That is, the uneven portion of the human power transmission body 113 meshes with the uneven portion 101a of the crank shaft 101.

Further, a magnetostriction generating portion 112b imparted with magnetic anisotropy is formed on the outer peripheral surface of the human power transmitter 113. A coil 112a is arranged on the outer periphery of the magnetostriction generating portion 112b of the human-powered transmitter 113 through a constant gap (space), and the magnetostriction type torque sensor 112 is configured by the magnetostriction generating portion 112b and the coil 112a. Then, the human-powered driving force transmitted from the crank shaft 101 to the human-powered transmission body 113 via the splines (or serrations) 101a and 113a is detected by the torque sensor 112.

Further, in the drive unit 110, an interlocking cylinder 114, a resultant force transmission body 115, or the like is provided with respect to the crank shaft 101 on a part of the outer peripheral side of the crank shaft 101 (the portion on the right side in FIG. 20) inside the drive unit 110. Is rotatably arranged. The resultant force transmission body 115 combines the human power driving force transmitted from the human power transmission body 113 via the interlocking cylinder 114 and the like and the auxiliary driving force transmitted from the motor 111 via the deceleration mechanism 120. Then, the end portion of the resultant force transmission body 115 is projected from the drive unit 110, and the resultant force (driving force in which human-powered driving force and auxiliary driving force are combined) is transmitted from the drive sprocket 105 attached to the protruding portion via the chain 106. Is transmitted to the rear wheel side.

When assembling the drive unit 110, the drive unit 110 is assembled by fitting the human-powered transmitter 113 to which the torque sensor 112 is assembled into the bearing 103 in a state where the torque sensor 112 is fitted to the crank shaft 101. Be done. After that, the crank arm 102 is fitted and attached to the end of the crank shaft 101. Therefore, the diameter of the crank shaft 101 is simply enlarged in FIG. 22 and emphasized in FIG. 22 so that such an assembly work can be performed without any trouble. The diameter d2 of the portion 101c received by the bearing 103 is larger than the diameter (specifically, the diameter of the outer peripheral portion having the maximum diameter) d1, and the portion (spline (or serration) 101a) to which the resultant force transmitter 115 is fitted is. It is formed so that the diameter (specifically, the diameter of the outer peripheral portion having the maximum diameter) d3 of the formed portion) becomes large. That is, the crank shaft 101 is formed in a so-called two-step stepped shape (a shape in which the stepped portion becomes thicker in order).

Further, as described above and as briefly shown in FIG. 23, the spline (or serration) 101a in which the human power transmission body 113 is fitted in the crank shaft 101 has a convex portion 101aa having an outer diameter (mountain portion) and an inward portion. A recessed recess (valley) 101ab is formed. Correspondingly, as simply shown in FIG. 24, the spline (or serration) 113a in which the crank shaft 101 is fitted in the human power transmission body 113 has a convex portion 113aa protruding inward and a concave portion outward. A recess (valley) 113ab is formed.

Then, as shown in FIGS. 23 and 24, the outer diameter of the portion (connecting fitting portion) 101b of the crank shaft 101 where the crank arm 102 is fitted and the portion where the human power transmission body 115 is fitted (spline (or spline)). Serration)) The radial difference (difference from the axis) A from the outer diameter of 101a is the convex portion 113aa on the inner surface of the place (spline (or serration) 113a) where the crank shaft 101 is fitted in the human power transmission body 113. It is formed larger than the radial dimensional difference (so-called height difference) B from the recess 113ab.

International Publication WO2015 / 186159 Gazette

By the way, it may be desired to make such a drive unit 110 smaller and closer to a general bicycle (so-called sports type bicycle or the like). However, the diameter d1 of the connecting fitting portion 101b with the crank arm 102 in the crank shaft 101 must secure a certain dimension and maintain a sufficient strength as the connecting strength at this portion. That is, as shown in FIG. 22, the diameter d2 of the portion 101c received by the bearing 103 is larger than the diameter d1 of the connecting fitting portion 101b of the crank shaft 101 with the crank arm 102, and the resultant force transmitter 115 is further formed. The diameter d3 of the fitted portion (the portion where the spline (or serration) 101a is formed) is gradually thicker in the stepped portion. Further, as shown in FIGS. 23 and 24, the outer diameter of the portion (connecting fitting portion) 101b of the crank shaft 101 where the crank arm 102 is fitted and the portion where the human power transmission body 115 is fitted (spline (or serration)). )) The radial difference A from the outer diameter of 101a is the radial dimensional difference (spline (or serration) 113a) between the convex portion 113aa and the concave portion 113ab at the position (spline (or serration) 113a) in which the crank shaft 101 is fitted in the human power transmission body 113. It is formed larger than the so-called height difference) B. If this structure is adopted, the torque sensor 112 also becomes large correspondingly. Therefore, if the torque sensor 112 and the large-diameter reduction gear 122 assembled to the intermediate shaft 116 are arranged so as not to come into contact with each other, the distance between the crank shaft 101 and the intermediate shaft 116 must be increased to some extent. As a result, there is a problem that the drive unit 110 cannot be miniaturized.

In recent years, as a standard for the bottom bracket (around the crank shaft) of a bicycle, there are standards such as the ISIS standard (International Spline Interface Standard) in which the diameter of the connecting fitting part with the crank arm on the crank shaft is relatively large. There is a tendency for sports-type bicycles that comply with various standards to be preferred. As described above, when the diameter of the connecting fitting portion of the crank shaft with the crank arm is large, the crank shaft has sufficient durability (strength) even when a larger force is applied to the crank shaft, thus improving reliability. However, in this case, the diameter R3 of the crank shaft 101 where the resultant force transmitter 115 is fitted and the torque sensor 112 also become large, so that the crank shaft 101 and the intermediate shaft 116 are further increased. The distance between the shafts and the shaft becomes larger, and the drive unit 110 cannot be miniaturized.

The present invention solves the above-mentioned problems, and the diameter of the connection fitting portion with the crank arm on the crank shaft is set to a size capable of obtaining sufficient connection strength, and the fitting with the human power transmission body on the crank shaft. It is an object of the present invention to provide an electrically assisted bicycle and a drive unit capable of making the diameter of the joint portion relatively small.

In order to solve the above problems, the present invention is a drive unit provided with the motor, which is attached to an electrically assisted bicycle capable of traveling by adding an auxiliary driving force by a motor to a human-powered driving force by pedaling force from a pedal. The crank shaft is arranged so as to penetrate the drive unit, and the human-powered driving force from the pedal is transmitted via the crank arm, and is fitted to the outer periphery of the crank shaft in the drive unit via a concave-convex portion. It has a combined human power transmission body and a driving force output wheel body to which the rotation of the human power transmission body is transmitted, and the human power driving force from the crank shaft outputs the driving force through the human power transmission body. The radial difference between the outer diameter of the part of the crank shaft where the crank arm is fitted and the outer diameter of the place where the human power transmission body is fitted is the difference in the radial direction of the crank of the human power transmission body. It is characterized in that it is smaller than the difference in the radial direction of the uneven portion formed on the inner surface of the portion where the shaft is fitted.

According to this configuration, the difference in the radial direction between the outer diameter of the place where the crank arm is fitted and the outer diameter of the place where the human power transmission body is fitted in the crank shaft is such that the crank shaft of the human power transmission body is fitted. Since it is smaller than the radial difference of the uneven portion formed on the inner surface of the portion, the human-powered transmitter on the crank shaft has a relatively large diameter at the portion where the crank arm is fitted. The outer diameter of the mated portion can be kept small.

Further, in the drive unit of the present invention, the uneven portion thereof is composed of splines or serrations, and the outer diameter of the portion of the crank shaft where the crank arm is fitted is outside the portion where the human power transmitter is fitted. It is characterized by being larger than the diameter and smaller than the diameter of the valley of the spline or serration formed on the inner surface of the portion where the crank shaft of the human power transmitter is fitted.

According to this configuration, in the fitting portion between the crank shaft and the human power transmission body, the portion having the outer diameter of the portion where the crank arm is fitted in the crank shaft and the corresponding portion in the human power transmission body (opposing each other). It is possible to form a gap (so-called play) with the location). As a result, at the fitting point between the crank shaft and the human power transmission body, the force that tries to bend the crank shaft (that is, the torque detection of the torque sensor) is compared with the case where the crank shaft is fitted without a gap by press fitting or the like. It is possible to reduce the transmission of (forces that may have an adverse effect) to the human-powered transmitter.

Further, in the drive unit of the present invention, the portion of the crank shaft to which the crank arm is fitted and the portion to which the human-powered transmitter is fitted have a mountain portion and a diameter protruding in the radial direction, respectively. The diameter of the valley, which is the diameter of the portion of the crank shaft where the valley where the crank arm is fitted is provided, has a valley that is recessed in the direction. It is characterized in that it is equal to or less than the diameter of the valley portion, which is the diameter of the portion where the valley portion of the mated portion is provided.

Further, in the drive unit of the present invention, the portion of the crank shaft to which the crank arm is fitted and the portion to which the human power transmission body is fitted have a mountain portion and a diameter protruding in the radial direction, respectively. It has a valley portion that is recessed in the direction, and a mountain portion is provided between a portion of the crank shaft to which the human power transmission body is fitted and a portion of the human power transmission body to which the crank shaft is fitted. It is characterized by having a gap in each portion of the valley portion and the valley portion.

According to this configuration, a gap is formed in each portion of the mountain portion and the valley portion between the portion where the human power transmission body is fitted in the crank shaft and the portion where the crank shaft is fitted in the human power transmission body. Can be (have so-called play). As a result, at the fitting point between the crank shaft and the human power transmission body, the force that tries to bend the crank shaft (that is, the torque detection of the torque sensor) is compared with the case where the crank shaft is fitted without a gap by press fitting or the like. It is possible to reduce the transmission of (forces that may have an adverse effect) to the human-powered transmitter.

Further, the drive unit of the present invention is characterized in that splines or serrations are formed at a portion of the crank shaft where the crank arm is fitted and a portion where the human-powered transmitter is fitted, respectively. And.

Further, in the drive unit of the present invention, a portion of the crank shaft between a portion where the crank arm is fitted and a portion where the human power transmission body is fitted is rotatably supported by a bearing. The radial difference between the outer diameter of the portion of the crank shaft supported by the bearing, the outer diameter of the portion where the human-powered transmitter is fitted, and the outer diameter of the portion where the crank arm is fitted is the above . It is characterized in that it is smaller than the difference in the radial direction of the uneven portion formed on the inner surface of the portion where the crank shaft of the human power transmitter is fitted. In this case, it is preferable that the restricting members for positioning the bearing in the axial direction are fitted on both sides of the crank shaft in the axial direction of the bearing. Further, an oil sealing material may be arranged between the crank shaft and the bearing.

Further, the drive unit of the present invention is characterized in that a resultant force obtained by combining the human-powered driving force with the auxiliary driving force by the motor is transmitted to the driving force output wheel body .
Further, the drive unit of the present invention is provided with an intermediate shaft that rotates at an axis different from that of the crank shaft, and the intermediate shaft has a reduction gear and an auxiliary sprocket that meshes with an endless driving force transmitter. Attached, the auxiliary driving force of the motor is transmitted to the auxiliary sprocket via the reduction gear.

Further, the present invention is an electrically assisted bicycle provided with the drive unit.
The drive unit is disposed at an intermediate position between the front wheels and the rear wheels.

According to the present invention, the difference in the radial direction between the outer diameter of the place where the crank arm is fitted and the outer diameter of the place where the human power transmission body is fitted in the crank shaft is such that the crank shaft of the human power transmission body is fitted. By making it smaller than the difference in the radial direction of the uneven portion formed on the inner surface of the portion, even if the diameter of the portion where the crank arm is fitted on the crank shaft is relatively large, human power transmission on the crank shaft is performed. The outer diameter of the place where the body is fitted can be kept small. As a result, the distance between the crank shaft and the intermediate shaft can be kept small, and the drive unit can be miniaturized.

Overall left side view of the electrically power assisted bicycle according to the first embodiment of the present invention. A plan sectional view of a drive unit of an electrically power assisted bicycle according to the same embodiment. Simple left side sectional view of the drive unit Enlarged plan view of the main part of the drive unit Enlarged plan view of the main part of the drive unit Left side view of the fitting part of the crank shaft of the same drive unit with the crank arm Side sectional view of the fitting portion of the crank shaft of the drive unit with the human power transmission body. Side sectional view of the fitting portion of the human-powered transmitter of the same drive unit with the crank shaft. Side sectional view of the fitting portion of the human-powered transmitter and the crank shaft of the drive unit. Enlarged side sectional view of the main part of the fitting point of the human power transmission body and the crank shaft of the drive unit. Enlarged side view of the main part of the drive unit in which the fitting points of the human-powered transmitter and the crank shaft are further enlarged. Enlarged plan view of the main part of the modified example of the drive unit of the same embodiment. Side sectional view of the fitting portion of the human-powered transmitter and the crank shaft of the modified example of the drive unit. Enlarged side view of the main part of the fitting part of the human-powered transmitter and the crank shaft of the modified example of the drive unit. An enlarged side sectional view of a main part in which the fitting portion of the human-powered transmitter and the crank shaft of the modified example of the drive unit is further enlarged. A plan sectional view of a drive unit or the like according to another embodiment of the present invention (second embodiment). Overall right side view of the electrically power assisted bicycle according to the third embodiment of the present invention. Right side view of the main part of the electrically power assisted bicycle An exploded perspective view of the hanger and crank unit of the electrically power assisted bicycle Vertical cross-sectional view of the hanger of the electrically power assisted bicycle and the location near the hanger Plane cross-sectional view of the drive unit of a conventional electrically power assisted bicycle Enlarged plan view of the main part of the crank shaft of the conventional electrically power assisted bicycle Enlarged side view of the main part of the crank shaft of the conventional electrically power assisted bicycle Enlarged side view of the main part of the human power transmission body of the conventional electrically power assisted bicycle

Hereinafter, the electrically power assisted bicycle and the drive unit according to the embodiment of the present invention will be described with reference to the drawings. In the following description, the left-right direction and the front-back direction refer to the direction in which the electrically power assisted bicycle is in the traveling direction. Further, the configuration of the present invention is not limited to the configuration described below.

1 in FIG. 1 is an electrically assisted bicycle according to an embodiment of the present invention. As shown in FIG. 1, the electrically assisted 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 standing pipe 2d, a chain stay 2e, a seat stay 2f, and the like. The front wheel 3 rotatably attached to the lower end of the front fork 2b, the rear wheel 4 rotatably attached to the rear end of the chain stay 2e, the handle 5 for changing the direction of the front wheel 3, and the passenger are seated. Includes a saddle 6, a crank 7 and a pedal 8 to which a human-powered driving force consisting of pedaling force is applied, an electric motor 21 (see also FIG. 2) as a driving source for generating an auxiliary driving force (assisting force), and this motor 21. A drive unit 20 provided with a control unit or the like for performing various electrical controls, a battery 12 including a secondary battery for supplying power for driving to the motor 21, and a passenger attached to a handle 5 or the like. The hand-operated unit 18 that can be operated such as, and can switch the power supply of the electrically assisted bicycle 1 and change the setting of the running mode, etc. And, it is attached to the drive sprocket (also called front sprocket, crank sprocket or front gear) 13 as a drive force output wheel body that outputs the resultant force combined with the auxiliary drive force, and the hub (also called rear hub) 9 of the rear wheel 4. As a rear sprocket (sometimes also referred to as a rear gear) 14 as a rear wheel body, and as an endless driving force transmitter wound endlessly over the drive sprocket 13 and the rear sprocket 14 in a rotatable state. It is equipped with a chain 15 and the like.

The electrically assisted bicycle 1 can travel by adding the auxiliary driving force generated by the motor 21 to the human-powered driving force generated by the pedaling force from the pedal 8, and the resultant force obtained by adding the auxiliary driving force to the human-powered driving force drives the bicycle. It is transmitted from the sprocket 13 to the rear wheel 4 via the chain 15 and the rear sprocket 14.

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

As shown in FIG. 1, in the electrically power assisted bicycle 1, the drive unit 20 is arranged at an intermediate position between the front wheels 3 and the rear wheels 4, more specifically, at a position where the crank shaft 7a is penetrated. With such an arrangement, the drive unit 20 having a relatively large weight is arranged at the center of the electrically power assisted bicycle 1 in the front-rear direction. As a result, the front wheels 3 and the rear wheels 4 can be easily lifted, and even if there is a step on the running path, it can be easily overcome. The sex is also good.

As shown in FIG. 2, in the drive unit 20, an outer shell portion and the like are configured by a unit case 22 composed of first to third cases 22a to 22c, and the drive unit 20 (in this embodiment, the rear portion of the drive unit 20). ), The crank shaft 7a penetrates left and right. Further, mounting bolts (not shown) or the like are inserted through a part of the first and second cases 22a and 22b, and the drive unit 20 is placed in the frame 2 (near the lower end portion of the lower pipe 2g or in a standing position). A mounting portion 22d to be attached to a portion near the lower end portion of the pipe 2d, a portion near the front end portion of the chain stay 2e, etc.) is provided. Further, a substantially tubular human power transmission body 28 to which the human power driving force from the crank shaft 7a is transmitted, and an interlocking cylinder 23 to which the human power driving force from the human power transmission body 28 is transmitted to the outer periphery of the crank shaft 7a. The human-powered driving force from the interlocking cylinder 23 is transmitted via a one-way clutch (one-way clutch for cutting the auxiliary driving force) 30, and the resultant force of the human-powered driving force and the auxiliary driving force from the motor 21 is combined. A resultant force transmitter 29 that transmits to the drive sprocket 13 is arranged. Further, the crank shaft 7a, the human power transmission body 28, the interlocking cylinder 23, the resultant force transmission body 29, and the like are arranged coaxially.

Further, in the unit case 22 of the drive unit 20, there is a deceleration mechanism 25 that decelerates the rotation of the motor 21 and transmits it to the resultant force transmission body 29 side (intermediate shaft 40 in this embodiment), and an auxiliary drive force (assist force). ) A motor 21 as a drive source is arranged. In the unit case 22 of the drive unit 20, a board (also referred to as a drive board or a main board) 24 provided with electronic components that perform various electrical controls is also arranged, and is mounted on the board 24 and this board. The control unit is composed of electronic parts and the like. As shown in FIGS. 2 and 3, the axis of the rotating shaft 21a of the motor 21, the axis of the crank shaft 7a, and the axis of the intermediate shaft 40 described later are different from each other. Further, in this embodiment, the rotary shaft 21a, the intermediate shaft 40, and the crank shaft 7a of the motor 21 are arranged in order from the front. However, the present invention is not limited to this, and the rotary shaft 21a, the intermediate shaft 40, and the crank shaft 7a of the motor 21 may be arranged in opposite directions in the front-rear direction.

Further, in the drive unit 20 (specifically, in the unit case 22 of the drive unit 20), a portion excluding both ends of the crank shaft 7a, a human power transmission body 28, an interlocking cylinder body 23, a resultant force transmission body 29, a deceleration mechanism 25, A motor 21, a torque sensor 31, a rotation detector 11, a rotation detector (rotation sensor) 10, and the like, which will be described later, are provided. The human-powered driving force and the auxiliary driving force are combined in the drive unit 20, and the combined combined force is generated from the drive sprocket 13 provided outside the drive unit 20 (specifically, outside the unit case 22 of the drive unit 20). It is output.

The drive unit 20 will be described in more detail. As shown in FIGS. 2 and 3, the crank shaft 7a is rotatably arranged by bearings (crank shaft bearings) 26 and 27 in a state of penetrating the rear portion of the drive unit 20 to the left and right. A cylindrical human-powered transmitter 28 is fitted to the outer periphery of the left side portion of the crank shaft 7a in a state of being integrally rotated with the crank shaft 7a via a spline (or serration) 7c as an uneven portion. A spline (or serration) 28b as an uneven portion is also formed at a portion corresponding to the spline (or serration) 7c of the crank shaft 7a on the inner circumference of the human power transmission body 28, and the spline (or serration) 7c of the crank shaft 7a is formed. Is in mesh with.

On the outer peripheral surface of the human power transmitter 28, a magnetostrictive generation portion 31a imparted with magnetic anisotropy is formed. Further, the coil 31b is arranged on the outer periphery of the magnetostriction generating portion 31a through a constant gap (space). The magnetostrictive generation unit 31a and the coil 31b constitute a magnetostriction type torque sensor (human power detection unit) 31. As a result, the human-powered driving force from the crank shaft 7a is transmitted to the human-powered transmission body 28, and the human-powered driving force is detected by the torque sensor 31. Further, in the magnetostriction type torque sensor 31, the magnetostriction generating portion 31b is formed in a spiral shape having, for example, +45 degrees and −45 degrees with respect to the axial direction of the human power transmitter 28. When the human-powered driving force is transmitted to the human-powered transmission body 28, the magnetostrictive generation portion 31b on the surface of the human-powered transmission body 28 is distorted to generate an increase portion and a decrease portion of the magnetic permeability. It is configured so that the magnitude of torque (human-powered driving force) can be detected by measuring the inductance difference. In the present embodiment, a magnetostrictive torque sensor is used as the torque sensor 31, but a strain-sensing torque sensor in which a strain sensor for detecting the physical strain of the human-powered conductor 28 is arranged on the outer peripheral surface of the human-powered conductor 28 is used. A sensor may be used.

The interlocking cylinder 23 is arranged on the outer periphery of the crank shaft 7a at a position adjacent to the right side of the human power transmission body 28 in a state of being rotatable with respect to the crank shaft 7a. A spline (or serration) 28a formed on the outer periphery of the right end portion of the human power transmission body 28 and a spline (or serration) 23a formed on the inner circumference of the left end portion of the interlocking cylinder 23 are fitted to each other to form the interlocking cylinder 23. Rotates integrally with the human power transmitter 28. In this embodiment, a spline (or serration) 23a formed on the inner circumference of the left end portion of the interlocking cylinder 23 is fitted to the spline (or serration) 28a of the human power transmission body 28 from the outside.

Further, in this embodiment, a rotation detecting body 11 for detecting the rotational state of the interlocking cylinder 23 is attached to the outer periphery of the left side portion of the interlocking cylinder 23. Further, a rotation detector (rotation sensor) 10 as a crank shaft rotation sensor is attached and fixed to the unit case 22 side so that the rotation detector 11 faces from the outer peripheral side. For example, in the rotation detector 10, optical sensors having an emitting unit and a light receiving unit are arranged in the rotation direction of the rotation detector 11 (not shown). The rotation detector 11 has a large number of tooth portions extending to the right in the shape of a comb tooth at a portion on the outer peripheral side thereof. Then, when there is a tooth portion of the rotation detector 11, the emitted light is reflected by the tooth portion and received by the rotation detector 10. As a result, the incident state and non-incident state of light are electrically detected by the light receiving unit of the rotation detector 10, and this signal is input by the control unit to rotate the rotation speed (rotation amount) and rotation of the interlocking cylinder 23. Detect the direction. In addition, instead of the optical sensor, a magnetic sensor such as a Hall IC may be provided to detect the rotation speed (rotation amount) and the rotation direction of the interlocking cylinder 23. Here, the interlocking cylinder 23 rotates integrally with the human power transmission body 28, and the human power transmission body 28 rotates integrally with the crank shaft 7a. As a result, the rotation amount and rotation direction of the interlocking cylinder 23 can be detected, and the rotation speed (rotation amount) and rotation direction of the crank shaft 7a and the pedal 8 can also be detected.

Further, a resultant force transmission body 29 is arranged on the outer periphery of the right side portion of the interlocking cylinder 23 via a one-way clutch (one-way clutch for cutting auxiliary driving force) 30. Then, when the pedal 8 is pedaled to move forward, the human-powered driving force transmitted to the interlocking cylinder 23 is transmitted to the resultant force transmission body 29 via the one-way clutch 30.

The rotary shaft 21a and the rotor 21b of the motor 21 are rotatably supported by the motor shaft bearings 32 and 33. Further, the rotating shaft 21a of the motor 21 is projected to the right side, and a motor shaft reduction gear 39 described later is formed on the outer periphery of the protruding portion.

The reduction gear 25 includes an intermediate shaft 40 arranged in parallel with the crank shaft 7a, and a large-diameter reduction gear (first reduction gear: crank shaft side reduction gear) 36 formed on the left side portion of the resultant force transmission body 29. It has two pairs of reduction gears 36 to 39 including the above, and constitutes a two-stage reduction mechanism. Then, the deceleration mechanism 25 combines the human-powered driving force transmitted through the crank shaft 7a and the auxiliary driving force transmitted from the motor 21, and the resultant force formed by combining the human-powered driving force and the auxiliary driving force. Is transmitted to the resultant force transmitter 29.

The intermediate shaft 40 is arranged so as to extend left and right in the central portion of the drive unit 20 in the front-rear direction and to be rotatably supported by bearings (intermediate shaft bearings) 34 and 35 in a posture parallel to the crank shaft 7a. .. A second intermediate shaft reduction gear 37 having a large diameter, a third intermediate shaft reduction gear 38 having a small diameter, and a one-way clutch 42 for cutting a human-powered driving force are attached to the intermediate shaft 40.

The one-way clutch 42 for cutting the human-powered driving force is arranged between the outer circumference of the intermediate shaft 40 and the inner circumference of the second intermediate shaft reduction gear 37 to cut off the human-powered driving force from the pedal 8. belongs to. That is, when the motor 21 is not driven by the one-way clutch 42 and the auxiliary driving force is not generated, the human-powered driving force from the pedal 8 is disengaged by the one-way clutch 42 for cutting the human-powered driving force. Therefore, it is not necessary to rotate the rotor 21b of the motor 21. On the other hand, when the 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 are connected. 37 and 38 rotate integrally with the intermediate shaft 40.

Then, 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, the motor 21 is rotated and an auxiliary driving force is output. In this case, the rotation of the motor 21 is decelerated, and the torque of the auxiliary driving force from the motor 21 is amplified and transmitted to the intermediate shaft 40 side. Further, since the small diameter third intermediate shaft 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 auxiliary driving force transmitted to the intermediate shaft 40 Is further amplified and transmitted to the first reduction gear 36. Then, in the resultant force transmission body 29 in which the first reduction gear 36 is integrally formed, the human-powered driving force and the auxiliary driving force from the motor 21 are combined and output from the driving sprocket 13 as the driving force output wheel body. To.

Here, as shown in an enlarged manner in FIGS. 4 to 10, the outer diameter (specifically, the diameter of the outer peripheral portion) D1 of the crank shaft 7a where the crank arm 7b is fitted and the human-powered transmitter 28 are fitted. A radial difference (difference in radial dimension from the axis X of the crank shaft 7a) A1 with the outer diameter D2 of the fitted portion is formed on the inner surface of the portion where the crank arm 7b of the human power transmission body 28 is fitted. It is made smaller than the radial difference (so-called height difference of the uneven portion) B1 of the spline (or serration) 28b as the uneven portion. Further, in this embodiment, a spline (or serration) 7d as an uneven portion is also formed at a position where the crank arm 7b of the crank shaft 7a is fitted, and correspondingly, the crank shaft of the crank arm 7b is formed. A spline (or serration) 7e as an uneven portion is also formed at the fitting portion of the 7a.

That is, the portion where the human power transmission body 28 in the crank shaft 7a is fitted and the portion where the crank shaft 7a in the human power transmission body 28 is fitted correspondingly are peaks protruding in the radial direction, respectively. Splines (or serrations) 7c and 28b are formed as uneven portions having a portion and a valley portion recessed in the radial direction. Further, in the place where the human power transmission body 28 is fitted in the crank shaft 7a and the place where the crank shaft 7a in the crank arm 7b is fitted, there are mountain portions protruding in the radial direction and a radial portion in the radial direction, respectively. On the other hand, splines (or serrations) 7d and 7e are formed as uneven portions in which recessed valley portions are provided at predetermined angles. Further, the outer diameter D1, which is the diameter of the portion of the crank shaft 7a where the mountain portion of the spline (or serration) 7d fitted to the crank arm 7b is provided, is a spline fitted to the human-powered transmitter 28 of the crank shaft 7a. (Or serration) On the inner surface of the portion (spline (or serration) 7d) where the crank shaft 7a of the human power transmitter 27 is fitted, which is larger than the outer diameter D2 which is the diameter of the portion where the peak portion of 7c is provided. It is formed smaller than the formed inner diameter (diameter between the splines of the human power transmitter 27 or the valley of the serration 7d). Then, as described above, the radial difference between the outer diameter D1 of the place where the crank arm 7b is fitted and the outer diameter D2 of the place where the human power transmission body 28 is fitted (from the axial center X of the crank shaft 7a). Radial difference) A1 is the radial difference of the spline (or serration) 28b as the uneven portion formed on the inner surface of the place where the crank arm 7b of the human power transmission body 28 is fitted (the height of the so-called uneven portion). Difference) It is smaller than B1.

Further, as shown in an enlarged scale in FIG. 11, a mountain portion is formed between the portion where the human power transmission body 28 in the crank shaft 7a is fitted and the portion where the crank shaft 7a in the human power transmission body 28 is fitted. And each part of the valley part is formed so as to have a gap (so-called play). The preferred size of this gap is m (module) = d (reference circle diameter) / at the location where the splines (or serrations) 7c and 28b, which are the fitting portions of the crank shaft 7a and the human power transmission body 28, are provided. When indicated by z (number of teeth), the gap E between the mountain portion of the crank shaft 7a and the corresponding portion of the human power transmission body 28 is 0 to 0.25 m (for example, 0.001 m larger than 0). The above) and 0.25 m or less) are suitable. Further, the gap F between the valley portion of the crank shaft 7a and the corresponding portion of the human power transmission body 28 is 0 to 0.1 m (greater than 0 (for example, 0.001 m or more), 0.1 m or less). Suitable. The height (radial dimension) of the spline (or serration) 7c where the human power transmission body 28 is fitted in the crank shaft 7a is set to, for example, 2.25 m, but the height is not limited to this.

Further, the spline (or serration) 7c formed at the portion of the crank shaft 7a where the human-powered transmitter 28 is fitted is extended to the portion where the human-powered transmitter 28 is fitted with the bearing 26. That is, the portion of the crank shaft 7a between the place where the human power transmission body 28 is fitted (spline (or serration) 7c) and the place where the crank arm 7b is fitted (spline (or serration) 7d) is a bearing. It is rotatably supported by (bearing arranged on the left side in this embodiment) 26. Then, the outer diameter D3 of the portion of the crank shaft 7a supported by the bearing 26, the outer diameter D2 of the portion (spline (or serration)) to which the human power transmission body 28 is fitted, and the crank arm 7b are fitted. The crank arm 7b of the human-powered transmitter 28 is fitted with a radial difference (difference in radial dimension from the axial center X of the crank shaft 7a) with the outer diameter D1 of the location (spline (or serration) 7d). The difference in the radial direction (so-called height difference of the uneven portion) B1 of the spline (or serration) 28b as the uneven portion formed on the inner surface of the portion is made smaller. In this embodiment, the outer diameter D3 of the portion of the crank shaft 7a supported by the bearing 26 is the same as the outer diameter D2 of the portion (spline (or serration) 7c) to which the human power transmission body 28 is fitted. However, it is not limited to this.

However, as shown in FIGS. 9 and 10, the diameter (valley diameter) T1 of the portion of the crank shaft 7a where the valley portion where the crank arm 7b is fitted is provided is the human power transmission in the crank shaft 7a. It is smaller than the diameter (valley diameter) T2 of the portion where the valley portion of the portion where the body 28 is fitted is provided. In this way, the diameter (valley diameter) T1 of the portion of the crank shaft 7a where the crank arm 7b is fitted is provided, and the portion of the crank shaft 7a where the human-powered transmitter 28 is fitted. When the diameter (valley diameter) of the portion where the valley portion is provided is T2 or less, it is easy to process the valley portion on the crank shaft. Further, in this embodiment, the number of ridges and valleys of the crank shaft 7a where the human-powered transmitter 28 is fitted is the same as the number of ridges and valleys of the crank shaft 7a where the crank arm 7b is fitted. The number of parts is doubled, and the mountain part of the crank shaft 7a where the crank arm 7b is fitted is the mountain part of the crank shaft 7a where the human power transmitter 28 is fitted. It is formed to correspond to. That is, in this embodiment, every other mountain portion of the crank shaft 7a where the crank arm 7b is fitted is every other mountain portion of the crank shaft 7a where the human power transmission body 28 is fitted. (That is, adjacent peaks are formed at double angles in the circumferential direction).

Further, as shown in FIGS. 4 and 5, in this embodiment, splines (splines (or serrations) 7c) peaks are formed on both sides (left side and right side) of the bearing 26 in the crank shaft 7a in the axial direction. The outer peripheral side portion is shaved to form a groove portion 7f, and a regulating member 43 for positioning the bearing 26 so as not to move in the axial direction (that is, in the left-right direction) is fitted in each of the groove portions 7f. It has been combined. Also, in the axial direction (that is, in the left-right direction), at the intermediate point between both regulating members 43, in the circumferential direction at the same depth as the valley portion of the spline (spline (or serration) 7c). A groove portion 7g is formed, and an oil sealing material 44 that seals between the crank shaft 7a and the human power transmission body 28 in the radial direction is arranged in the groove portion 7g. The oil sealing material 44 can prevent water and mud from entering the inside of the unit case 22 from the outside. Further, the lubricating oil applied to the reduction gears 36 to 39 and the like is prevented from leaking from the inside of the drive unit 20 to the outside of the drive unit 20 through the gap between the crank shaft 7a and the human power transmission body 28. It has become.

In this embodiment, a flange-shaped portion 7i projecting to the inner peripheral side is integrally formed adjacent to the spline (or serration) 7d that fits with the spline (or serration) 7d of the crank shaft 7a in the crank arm 7b. Has been done. When assembling the crank arm 7b to the crank shaft 7a, the flange-shaped portion 7i of the crank arm 7b is fitted to the crank shaft 7a from the side until it abuts from the side, and then the fixing member 45 is attached from the outside of the crank arm 7b. The male screw portion 45a is screwed into the female screw portion 7h formed on the inner circumference of the end portion of the crank shaft 7a, and the crank arm 7b is fixed so as not to come off. The 46 is a washer sandwiched between the crank arm 7b and the fixing member 45, and may be provided as needed.

According to the above configuration, in the crank shaft 7a, the outer diameter D1 of the place where the crank arm 7b is fitted (spline (or serration) 7d) and the place where the human power transmission body 28 is fitted (spline (or serration) 7c). ) The difference A1 in the radial direction from the outer diameter D2 is larger than the difference in the radial direction B1 of the spline (or serration) 7c as the uneven portion formed on the inner surface of the portion where the crank shaft 7a of the human power transmitter 28 is fitted. small. Further, in the present embodiment, the outer diameter D3 of the portion of the crank shaft 7a supported by the bearing 26 is also the outer diameter D2 of the portion (spline (or serration) 7c) to which the human power transmission body 28 is fitted. It is the same. Therefore, even when the diameter (outer diameter) of the portion (spline (or serration) 7d) where the crank arm 7b is fitted in the crank shaft 7a is relatively large, the human-powered transmitter 28 in the crank shaft 7a is fitted. The outer diameter D2 of the location (spline (or serration) 7c) can be kept small, and the size (diameter) of the torque sensor 31 can also be kept small. As a result, the distance between the crank shaft 7a and the intermediate shaft 40 can be kept small, and the drive unit 20 can be miniaturized.

In the crank shaft 7a, the outer diameter D1 of the place where the crank arm 7b is fitted (spline (or serration) 7d) and the outer diameter of the place where the human power transmitter 28 is fitted (spline (or serration) 7c). The radial difference A1 from D2 is within 90% of the radial difference B1 of the spline (or serration) 28b as an uneven portion formed on the inner surface of the portion where the crank shaft 7a of the human power transmission body 28 is fitted. It is preferable, and more preferably 50% or less is more preferable.

Further, in the above embodiment, the outer diameter D3 of the portion of the crank shaft 7a supported by the bearing 26 and the outer diameter D2 of the portion (spline (or serration)) where the human power transmission body 28 is fitted and the crank arm 7b. Radial difference A1 from the outer diameter D1 of the place where is fitted is the radial direction of the spline (or serration) 28b as an uneven portion formed on the inner surface of the place where the crank shaft 7a of the human power transmission body 28 is fitted. The difference is smaller than B1. Also by this, even when the diameter (outer diameter) of the portion (spline (or serration) 7d) where the crank arm 7b is fitted in the crank shaft 7a is relatively large, it is supported by the bearing 26 in the crank shaft 7a. The outer diameter D3 of the bearing portion and the outer diameter D2 of the portion where the human power transmission body 28 is fitted (spline (or serration) 7c) in the crank shaft 7a can be suppressed to a small size, and the size (diameter) of the torque sensor 31 can be suppressed. ) Can also be kept small. As a result, the distance between the crank shaft 7a and the intermediate shaft 40 can be kept small, and the drive unit 20 can be miniaturized.

In recent years, as a standard for the bottom bracket (around the crank shaft) of a bicycle, there are standards such as the ISIS standard (International Spline Interface Standard) in which the diameter of the connecting fitting part with the crank arm on the crank shaft is relatively large. In order to comply with various standards, the diameter of the connecting fitting portion of the crank shaft 7a with the crank arm 7b is made relatively large, and sufficient durability (strength) is sufficient even if a larger force is applied from the crank arm 7b to the crank shaft 7a. ), As described above, the outer diameter D2 of the crank shaft 7a where the human power transmission body 28 is fitted (spline (or serration) 7c) can be suppressed to a small size, and the torque can be suppressed. The size (diameter) of the sensor 31 can be kept small, and the drive unit 20 can be miniaturized.

Further, according to the above configuration, a place where the human power transmission body 28 in the crank shaft 7a is fitted (spline (or serration) 7c) and a place where the crank shaft 7a in the human power transmission body 28 is fitted (spline (or serration) 7c). Gap E and F are formed in each of the mountain portion and the valley portion between the serration) 28b). As a result, at the fitting portion between the crank shaft 7a and the human power transmission body 28, a force for bending the crank shaft 7a (that is, a torque sensor 31) as compared with the case where the crank shaft 7a is fitted without a gap by press fitting or the like. It is possible to reduce the transmission of the force (a force that may adversely affect the torque detection) to the human power transmission body 28.

That is, when the pedal 8 is stepped on, a force for bending the crank shaft 7a in a direction orthogonal to the axis X acts in addition to a force for twisting the crank shaft 7a in the axis rotation direction. Without the gaps E and F, the force for bending the crank shaft 7a is directly transmitted to the magnetostriction generating portion 31a of the torque sensor 31 via the human power transmission body 28. The force that tries to bend the crank shaft 7a becomes noise when detecting the torque (force that twists in the shaft rotation direction) of the torque sensor 31, which adversely affects the detection accuracy of the torque sensor 31.

On the other hand, a place where the human power transmission body 28 in the crank shaft 7a is fitted (spline (or serration) 7c) and a place where the crank shaft 7a in the human power transmission body 28 is fitted (spline (or serration) 28b). ), By providing the gaps E and F, the force for bending the crank shaft 7a is reduced to be transmitted to the human power transmission body 28, and the detection accuracy of the torque sensor 31 is less likely to decrease. As a result, the reliability of the electric bicycle 1 can be improved.

Further, according to the above configuration, the number of peaks and valleys where the human-powered transmitter 28 is fitted on the crank shaft 7a is the number of peaks and valleys where the crank arm 7b is fitted on the crank shaft 7a. The number of parts is doubled, and the part that becomes the mountain part of the crank shaft 7a where the crank arm 7b is fitted is the mountain part of the crank shaft 7a where the human power transmitter 28 is fitted. The human-powered driving force (treading force) acting on the crank shaft 7a is transmitted to the human-powered transmitter 28 through the spline (or serration) 7c in which many peaks and valleys are formed. Therefore, the torque can be detected with good sensitivity by the torque sensor 31 in which the magnetic strain generating portion 31b is formed on the outer periphery of the human power transmission body 28. That is, the shape of the spline (or serration) 7c where the human power transmission body 28 on the crank shaft 7a is fitted is the shape of the spline (or serration) 7d where the crank arm 7b on the crank shaft 7a is fitted. Even when the shape is the same, it is possible to fit the human power transmission body 28 to the crank shaft 7a, but the peaks and valleys of the parts of the crank shaft 7a where the human power transmission body 28 is fitted are If the number is larger, the torque can be detected with good sensitivity (accuracy), and the reliability is improved.

Further, by making the number of peaks of the fitting portion of the human power transmission body 28 and the fitting portion of the crank arm 7b on the crank shaft 7a different from each other, or by making the diameter of the valley portion different, the crank arm 7b It is also possible to perform assembly by restricting the position of the crank shaft 7a in the axial direction (left-right direction in this embodiment).

Further, according to the above configuration, by providing the oil sealing material 44 that seals between the crank shaft 7a and the human power transmission body 28 in the radial direction, the lubricating oil applied to the reduction gears 36 to 39 and the like can be removed. It is possible to satisfactorily prevent leakage from the inside of the drive unit 20 to the outside of the drive unit 20 through the gap between the crank shaft 7a and the human power transmission body 28.

Further, in the above embodiment, the outer diameter D1, which is the diameter of the portion of the crank shaft 7a where the mountain portion of the spline (or serration) 7d fitted to the crank arm 7b is provided, is the human power transmission body in the crank shaft 7a. The case where the outer diameter D2, which is the diameter of the portion where the mountain portion of the spline (or serration) 7c to be fitted to 28 is provided, is formed larger than the outer diameter D2 has been described, but the present invention is not limited to this. That is, the outer diameter D1, which is the diameter of the portion of the crank shaft 7a where the mountain portion of the spline (or serration) 7d fitted to the crank arm 7b is provided, is the spline fitted to the human-powered transmitter 28 of the crank shaft 7a. (Or serration) It may be formed smaller than the outer diameter D2, which is the diameter of the portion where the peak portion of 7c is provided.

Further, as shown in FIGS. 12 to 15, the outer diameter D1 (specifically, the diameter of the outer peripheral portion) of the crank shaft 7a where the crank arm 7b is fitted is fitted with the human power transmission body 28. The outer diameter D2 of the portion may be the same as the dimension (a modification of the first embodiment). That is, the outer diameter D1 which is the diameter of the portion of the crank shaft 7a where the mountain portion of the spline (or serration) 7d fitted to the crank arm 7b is provided, and the spline fitted to the human-powered transmitter 28 on the crank shaft 7a. (Or serration) The outer diameter D2, which is the diameter of the portion where the peak portion of 7c is provided, has the same dimensions.

Further, the portion of the crank shaft 7a between the place where the human power transmission body 28 is fitted (spline (or serration) 7c) and the place where the crank arm 7b is fitted (spline (or serration) 7d) is a bearing. Although it is rotatably supported by (the bearing arranged on the left side in this embodiment) 26, the human power transmission body 28 is also fitted to the outer diameter D3 of the portion supported by the bearing 26 in the crank shaft 7a. It is the same as the outer diameter D2 of the place where the crank arm 7b is fitted (spline (or serration) 7c) and the outer diameter D1 of the place where the crank arm 7b is fitted (spline (or serration) 7d).

According to the above configuration, the outer diameter D1 of the crank shaft 7a where the crank arm 7b is fitted (spline (or serration) 7d) and the location where the human power transmitter 28 is fitted (spline (or serration)). 7c) is the same as the outer diameter D2 (in the present embodiment, the outer diameter D3 of the portion supported by the bearing 26 in the crank shaft 7a is also the same). Therefore, even when the diameter (outer diameter) of the portion (spline (or serration) 7d) where the crank arm 7b is fitted in the crank shaft 7a is relatively large, the human-powered transmitter 28 in the crank shaft 7a is fitted. The outer diameter D2 of the location (spline (or serration) 7c) can be minimized, and the size (diameter) of the torque sensor 31 can also be minimized. As a result, the distance between the crank shaft 7a and the intermediate shaft 40 can be minimized, and the drive unit 20 can be miniaturized.

Further, in the above embodiment, the human-powered driving force and the auxiliary driving force are combined in the drive unit 20, and the combined resultant force is outside the drive unit 20 (specifically, outside the unit case 22 of the drive unit 20). Although the case of the configuration (so-called uniaxial drive unit 20) output from the drive sprocket 13 provided in the above is described, the present invention is not limited to this.

As shown in FIG. 16, in this embodiment, the auxiliary driving force from the motor 21 is rotatably supported in a state of being exposed to the outside of the drive unit 20'via the reduction gear 37 of the reduction mechanism 25 and the like. It is output to the auxiliary sprocket 61. That is, it is a so-called biaxial drive unit 20'. Then, only the human-powered driving force input to the pedal 8 is output from the drive sprocket 13 that is rotatable at the coaxial center with the crank shaft 7a, and the chain 15 as the driving force transmitting means assists the human-powered driving force and the motor 21. The driving force is combined and output to the rear wheel 4 side. In the embodiment shown in FIG. 15, a drive sprocket 13 that outputs a human-powered driving force is attached to the auxiliary interlocking cylinder 23B in which the rotation of the interlocking cylinder 23A is transmitted via the one-way clutch.

Also in this embodiment, the configuration of the fitting portion of the crank shaft 7a and the driving force transmission body 28 provided with the torque sensor, and the configuration of the fitting portion of the crank shaft 7a and the crank arm 7b are the above-described embodiments. Is similar to. The same reference numerals are given to the members having the same operation as that of the above embodiment.

Further, as in the above embodiment, also in this embodiment (second embodiment), as shown in FIGS. 16 and 6 to 11, the crank arm 7b in the crank shaft 7a is fitted. Radial difference between the outer diameter (specifically, the diameter of the outer peripheral portion) D1 and the outer diameter D2 of the place where the human power transmitter 28 is fitted (difference in radial dimension from the axial center X of the crank shaft 7a). ) A1 is larger than the radial difference (so-called height difference of the uneven portion) B1 of the spline (or serration) 28b as the uneven portion formed on the inner surface of the portion where the crank arm 7b of the human power transmission body 28 is fitted. It has been made smaller. Further, a spline (or serration) 7d as an uneven portion is also formed at a portion of the crank shaft 7a where the crank arm 7b is fitted, and correspondingly, a spline (or serration) 7d is formed at the fitting portion of the crank shaft 7a of the crank arm 7b. A spline (or serration) 7e is formed as an uneven portion.

That is, the portion where the human power transmission body 28 in the crank shaft 7a is fitted and the portion where the crank shaft 7a in the human power transmission body 28 is fitted correspondingly are peaks protruding in the radial direction, respectively. Splines (or serrations) 7c and 28b are formed as uneven portions having a portion and a valley portion recessed in the radial direction. Further, in the place where the human power transmission body 28 is fitted in the crank shaft 7a and the place where the crank shaft 7a in the crank arm 7b is fitted, there are mountain portions protruding in the radial direction and a radial portion in the radial direction, respectively. On the other hand, splines (or serrations) 7d and 7e are formed as uneven portions in which recessed valley portions are provided at predetermined angles. Further, in this embodiment, the outer diameter D1, which is the diameter of the portion of the crank shaft 7a where the mountain portion of the spline (or serration) 7d fitted to the crank arm 7b is provided, is a human-powered transmitter in the crank shaft 7a. A location (spline (or serration)) where the crank shaft 7a of the human-powered transmitter 27 is fitted, which is larger than the outer diameter D2, which is the diameter of the portion of the spline (or serration) 7c that fits 28. ) 7d) is formed smaller than the inner diameter (diameter between the splines of the human power transmitter 27 or the valley of the serration 7d) formed on the inner surface. Further, the connecting structure of the other crank shaft 7a, the human power transmission body 28, the torque sensor 31, and the crank arm is the same as that of the first embodiment and the second embodiment described above.

Further, as shown in an enlarged scale in FIG. 15, a mountain portion is formed between the portion where the human power transmission body 28 in the crank shaft 7a is fitted and the portion where the crank shaft 7a in the human power transmission body 28 is fitted. And each part of the valley part is formed so as to have a gap (so-called play).

That is, even in this configuration, the outer diameter D1 of the crank shaft 7a where the crank arm 7b is fitted (spline (or serration) 7d) and the human-powered transmitter 28 are fitted (spline (or serration)). The difference in the radial direction from the outer diameter D2 of 7c) is from the difference in the radial direction of (spline (or serration) 7c) as the uneven portion formed on the inner surface of the portion where the crank shaft 7a of the human power transmitter 28 is fitted. Is also small. With this configuration, even when the diameter (outer diameter) of the portion (spline (or serration) 7d) where the crank arm 7b is fitted in the crank shaft 7a is relatively large, the human power transmission body 28 in the crank shaft 7a can be used. The outer diameter D2 of the mated portion (spline (or serration) 7c) can be kept small, and the size (diameter) of the torque sensor 31 can also be kept small. As a result, the distance between the crank shaft 7a and the intermediate shaft 40 can be kept small, and the drive unit 20 can be miniaturized.

In the first and second embodiments, the case where the crank shaft 7a has a structure that penetrates the inside of the drive unit 20 provided with the motor 21 that generates the auxiliary driving force has been described, but the present invention is limited to this. It's not a thing.

17 to 20 show the electrically power assisted bicycle 50 according to the third embodiment of the present invention. As shown in FIG. 17, in the electrically power assisted bicycle 50 of this embodiment, the electric motor 21 is a front wheel. It is arranged inside the hub (also referred to as a front hub) 16 of 3. Further, although the control unit (not shown) is arranged near the mounting portion of the battery 12, the control unit may be arranged at another location such as the hand operation unit. The electric motor 10 may be disposed inside the hub (rear hub) of the rear wheel 4 instead of being disposed inside the front hub 16. The same components as those of the electrically power assisted bicycle 1 according to the first embodiment are designated by the same reference numerals.

In this embodiment, the drive unit that generates the auxiliary driving force is provided inside the front hub 16 (or the rear hub), and the auxiliary driving force is applied from the front hub 16 of the front wheel 3 or the rear hub of the rear wheel 4. It is supposed to be done. On the other hand, the structure of the torque sensor 31 itself that detects the human-powered driving force due to the pedaling force is the same as that of the above-described embodiment.

As briefly shown in FIG. 18, in this embodiment, the rear end portion of the lower pipe 2g, the lower end portion of the vertical pipe 2d, and the front end portion of the chain stay 2e are arranged in a state of being connected by a hanger 2h. Has been done. Then, as shown in FIGS. 19 and 20, the crank shaft 7a is rotatably arranged inside the hanger 2h via the bearings 26 and 27, and the torque sensor 31 detects the force corresponding to the pedaling force. Are arranged. Note that, in FIG. 9, regarding the drive sprocket 13, only the portion of the drive sprocket 13, which is also referred to as a spider, that supports the gear portion 13a is shown.

As shown in FIG. 20, in this embodiment, a metal middle cylinder 51 is arranged inside the hanger 2h, and a crank shaft 7a and the like are provided via bearings 26 and 27 provided inside the middle cylinder 51. It is rotatably supported. On the outer periphery of the crank shaft 7a, a cylindrical human-powered transmission body 28, an interlocking cylinder 23 interlocking with the drive sprocket 13, and the like are arranged. Reference numeral 52 in FIGS. 19 and 20 is a fixed cylinder that is fitted and fixed from the left side with the middle cylinder or the like inserted in the hanger 2h.

As shown in FIG. 20, similarly to the above embodiment, the crank shaft 17 is a spline (or serration) in which a human power transmission body 28 for transmitting human power driving force is fitted from the outer periphery in an intermediate portion in the axial direction. 7c is formed, and correspondingly, a spline (or serration) 28b that fits into the spline (or serration) 7c of the crank shaft 17 is also formed on the inner circumference of the left side portion of the human power transmission body 28. There is. Further, the human power transmission body 28 and the interlocking cylinder 23 are configured to be integrally interlocked with each other via the spline (or serration) 23a and 28a, and further, the interlocking cylinder 23 and the drive sprocket 13 are both splined (or serration) 23b. , 13b are configured to be integrally interlocked with each other, whereby the rotational driving force (human power driving force) of the crank shaft 7a is transmitted to the drive sprocket 13 via the human power transmission body 28 and the interlocking cylinder 23. Further, it is configured to be transmitted to the rear wheel 4 side via the chain 15. The interlocking cylinder 23 is rotatably arranged on the outer periphery of the crank shaft 7a, and the interlocking cylinder 23 and the crank shaft 7a are rotatably arranged by the bearing 27 assembled on the outer periphery of the interlocking cylinder 23. It is supported.

Also in the above configuration, the outer diameter D1 of the crank shaft 7a where the crank arm 7b is fitted (spline (or serration) 7d) and the location where the human power transmitter 28 is fitted (spline (or serration) 7c)). Radial difference from the outer diameter D2 (difference in radial dimension from the axis X of the crank shaft 7a) A1 is an uneven portion formed on the inner surface of the portion where the crank arm 7b of the human power transmission body 28 is fitted. The radial difference is smaller than the radial difference (so-called height difference of the uneven portion) B1 of the uneven portion formed on the inner surface of the portion where the crank shaft 7a of the human power transmission body 28 is fitted (so-called uneven portion height difference). (See FIGS. 9 to 11 and the like). Therefore, even when the diameter (outer diameter) of the portion (spline (or serration) 7d) where the crank arm 7b is fitted in the crank shaft 7a is relatively large, the human-powered transmitter 28 in the crank shaft 7a is fitted. The outer diameter D2 of the location (spline (or serration) 7c) can be kept small, and the size (diameter) of the torque sensor 31 can also be kept small. As a result, the crank shaft 7a and the torque sensor 31 can be arranged in the hanger 2h without any trouble without increasing the diameter of the hanger 2h.

In recent years, as a standard for the bottom bracket (around the crank shaft) of a bicycle, there are standards such as the ISIS standard (International Spline Interface Standard) in which the diameter of the connecting fitting part with the crank arm on the crank shaft is relatively large. In order to comply with various standards, the diameter of the connecting fitting portion of the crank shaft 7a with the crank arm 7b is made relatively large, and sufficient durability (strength) is sufficient even if a larger force is applied from the crank arm 7b to the crank shaft 7a. ), As described above, the outer diameter D2 of the crank shaft 7a where the human power transmission body 28 is fitted (spline (or serration) 7c) can be suppressed to a small size, and the torque can be suppressed. The size (diameter) of the sensor 31 can also be kept small, and the crank shaft 7a and the torque sensor 31 can be arranged in the hanger 2h without any trouble.

Further, according to the above configuration, the number of peaks and valleys where the human-powered transmitter 28 is fitted on the crank shaft 7a is the number of peaks and valleys where the crank arm 7b is fitted on the crank shaft 7a. The number of parts is doubled, and the part that becomes the mountain part of the crank shaft 7a where the crank arm 7b is fitted is the mountain part of the crank shaft 7a where the human power transmitter 28 is fitted. The human-powered driving force (treading force) acting on the crank shaft 7a is transmitted to the human-powered transmitter 28 through the spline (or serration) 7c in which many peaks and valleys are formed. Therefore, the torque can be detected with good sensitivity by the torque sensor 31 in which the magnetic strain generating portion 31b is formed on the outer periphery of the human power transmission body 28. That is, the shape of the spline (or serration) 7c where the human power transmission body 28 on the crank shaft 7a is fitted is the shape of the spline (or serration) 7d where the crank arm 7b on the crank shaft 7a is fitted. Even when the shape is the same, it is possible to fit the human power transmission body 28 to the crank shaft 7a, but the peaks and valleys of the parts of the crank shaft 7a where the human power transmission body 28 is fitted are If the number is larger, the torque can be detected with good sensitivity (accuracy), and the reliability is improved.

Further, by making the number of peaks of the fitting portion of the human power transmission body 28 and the fitting portion of the crank arm 7b on the crank shaft 7a different from each other, or by making the diameter of the valley portion different, the crank arm 7b It is also possible to perform assembly by restricting the position of the crank shaft 7a in the axial direction (left-right direction in this embodiment).

The present invention is applicable to various electrically assisted bicycles capable of traveling by adding an auxiliary driving force generated by a motor to a human-powered driving force generated by pedaling force from a pedal, and various drive units attached to the electrically assisted bicycle. ..

1 Electric assist bicycle 2 Frame 3 Front wheel 4 Rear wheel 5 Handle 7 Crank 7a Crank shaft 7b Crank arm 7c, 7d Spline (or serration) (uneven part)
8 Pedal 12 Battery (capacitor)
13 Drive sprocket (driving force output wheel)
14 Rear sprocket 15 Chain (endless driving force transmitter)
20 Drive unit 21 Motor 23 Interlocking cylinder 28 Human-powered transmitter 28b Spline (or serration) (concavo-convex part)
40 Intermediate axis

Claims (11)

It is an electrically power assisted bicycle that can run by adding the auxiliary driving force of the motor to the human driving force of the pedaling force from the pedal.
The crank shaft, in which the human-powered driving force from the pedal is transmitted via the crank arm,
A human-powered transmitter that is fitted to the outer circumference of the crank shaft via an uneven portion and has a strain-generating portion of a torque sensor formed on the outer circumference.
Have,
A radial difference between the outer diameter of the crank shaft where the crank arm is fitted and the outer diameter of the place where the human power transmitter is fitted is formed on the inner surface of the place where the crank shaft of the human power transmitter is fitted. An electrically assisted bicycle characterized by being smaller than the radial difference of the uneven parts. The outer diameter of the part of the crank shaft where the crank arm is fitted is larger than the outer diameter of the place where the human power transmitter is fitted, and is formed on the inner surface of the place where the crank shaft of the human power transmitter is fitted. The electrically assisted bicycle according to claim 1, wherein the bicycle is smaller than the diameter of the valley of the spline or serration. In the crank shaft, the place where the crank arm is fitted and the place where the human power transmitter is fitted have a peak portion protruding in the radial direction and a valley portion recessed in the radial direction, respectively. ,
The valley diameter, which is the diameter of the part of the crank shaft where the valley where the crank arm is fitted is provided, is the diameter of the part where the valley where the human power transmitter is fitted is provided. The electrically assisted bicycle according to claim 1 or 2, wherein the diameter is equal to or less than the diameter of the valley portion. In the crank shaft, the place where the crank arm is fitted and the place where the human power transmitter is fitted have a peak portion protruding in the radial direction and a valley portion recessed in the radial direction, respectively. ,
A claim characterized by having a gap in each portion of a mountain portion and a valley portion between a portion of the crank shaft into which the human power transmission body is fitted and a portion of the human power transmission body in which the crank shaft is fitted. The electrically assisted bicycle according to any one of Items 1 to 3. One of claims 1 to 4, wherein splines or serrations are formed at a portion of the crank shaft where the crank arm is fitted and a portion where the human power transmission body is fitted, respectively. Electric assisted bicycle described in. The portion of the crank shaft between the location where the crank arm is fitted and the location where the human power transmitter is fitted is rotatably supported by bearings.
The radial difference between the outer diameter of the portion of the crank shaft supported by the bearing, the outer diameter of the portion where the human power transmitter is fitted, and the outer diameter of the portion where the crank arm is fitted is the difference in the radial direction of the human power transmitter. The electrically assisted bicycle according to any one of claims 1 to 5, wherein the difference in the radial direction is smaller than the difference in the radial direction of the uneven portion formed on the inner surface of the portion where the crank shaft is fitted. The electrically assisted bicycle according to claim 6, wherein a restricting member for positioning the bearing with respect to the axial direction is fitted on both sides of the crank shaft in the axial direction of the bearing. The electrically assisted bicycle according to claim 6 or 7, wherein an oil seal material is arranged between the crank shaft and the bearing. A drive unit with a motor is provided,
The electrically assisted bicycle according to any one of claims 1 to 8, wherein the crank shaft is arranged so as to penetrate the drive unit. The electrically assisted bicycle according to claim 9, wherein an intermediate shaft that rotates at an axis different from that of the crank shaft is provided, and a reduction gear is attached to the intermediate shaft. It is a drive unit equipped with the motor, which is attached to an electrically assisted bicycle that can run by adding an auxiliary driving force by a motor to a human-powered driving force by pedaling force from a pedal.
A crank shaft that is arranged through the drive unit and in which the human-powered driving force from the pedal is transmitted via the crank arm,
A human-powered transmitter that is fitted to the outer circumference of the crank shaft via an uneven portion in the drive unit and has a torque sensor strain generating portion formed on the outer circumference.
Have,
A radial difference between the outer diameter of the crank shaft where the crank arm is fitted and the outer diameter of the place where the human power transmitter is fitted is formed on the inner surface of the place where the crank shaft of the human power transmitter is fitted. A drive unit characterized in that it is smaller than the difference in the radial direction of the uneven portion.

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