JP2001225648A - Power assisted bicycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the operability of the stand of a power assisted bicycle. SOLUTION: A stand 34 is fixed to a stand shaft 5 provided on the lower part of a drive unit (power assist unit) 1. A power is transmitted from a motor M to the stand shaft 5 through a gear. The power is transmitted through a one-way clutch, and when the motor M is reversely rotated, or rotated in the direction opposite to the direction of generating an auxiliary force, the stand shaft 5 is rotated to raise the stand 34. A lock device for prohibiting the rotation of the stand 34 is manually energized while the stand is raised, whereby a sure parking state can be kept.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery-assisted bicycle, and more particularly to a battery-assisted bicycle with improved operability of a stand that allows a vehicle body to stand on its own when parking.

[0002]

2. Description of the Related Art An electric motor having a human-powered driving system for transmitting a pedaling force applied to a pedal to a rear wheel, and a motor driving system capable of adding auxiliary power to the human-powered driving system in accordance with the pedaling force. Assisted bicycles are known. Since this electric assist bicycle has a larger body weight than a bicycle having no electric assist device, a side stand that supports the vehicle body with only one side of the rear wheel is not suitable. On the other hand, a center stand that surrounds the rear wheel is suitable for supporting a bicycle with a large body weight, but when the bicycle stands on its own, the rear wheel must be lifted manually. Therefore, there is an inconvenience that a large operation force is required.

[0003] In view of the above, there has been proposed a stand capable of easily supporting a heavy bicycle by itself.
207845). In the bicycle described in this publication, a stand is held on a rotating shaft provided immediately before the rear wheel, and a manually operable locking member is attached to a ratchet claw fixed to the rotating shaft. Is engaged. The locking member is manually operable and can be engaged with the ratchet pawl at an arbitrary timing, so that the position of the stand can be fixed at an arbitrary rotation angle. That is, the stand can be fixed both in a state where the rear wheel is in contact with the ground and in a state where the rear wheel is floated. Therefore, when the weight of the vehicle body is large, the bicycle can be made independent by grounding the stand without lifting the rear wheel.

[0004]

According to the stand having the above structure, the electric assist bicycle having a relatively large body weight can be made independent with a small force. However, even if the stand can be made independent, the wheels may be rolled by a small external force and the bicycle may move because the wheels are kept in contact with the ground. Therefore, do not use human power,
There is a demand for a bicycle that can lift the rear wheel and stand alone on a stand by the addition of a very small amount of human power.

[0005] It is an object of the present invention to provide an electric assisted bicycle which can be self-sustained and parked reliably by an easy operation even when the weight of the vehicle body is heavy or heavy luggage is loaded. .

[0006]

In order to achieve the above object, the present invention comprises a human-powered drive unit including a pedal crankshaft for transmitting pedaling force and a motor for generating auxiliary power combined with the human-powered drive unit. A motor-assisted bicycle having a motor drive unit, a stand rotatably provided at a lower portion of the vehicle body, the vehicle body being able to stand on its own by rotating a predetermined angle, and the motor rotating the stand by the predetermined angle. It is characterized by having stand driving means. According to this feature, since the stand is driven by the motor, the stand can be easily erected even in an electric assist bicycle having a relatively large body weight.

The present invention more specifically relates to the following (a) to
Each of the points (g) has a feature. (A) The motor is a brushless motor, and the stand is driven by rotation in a direction opposite to a rotation direction when the motor generates the auxiliary force. Since the motor is a brushless motor, it does not require special circuit means for reverse rotation,
Since the rotation angle can be easily detected, a desired stand rotation angle can be easily set.

(B) A power transmission system including a one-way clutch is provided in the stand driving means in order to transmit only the reverse rotation of the motor to the stand. The structure for rotating the stand only when the motor rotates reversely can be simplified.

(C) The stand is provided with a rotating shaft below the motor drive section, and the stand drive means is formed integrally with the motor drive section. By being integrated with the motor drive unit, it is possible to reduce the size and weight by using a common casing and the like.

(D) The stand driving means is provided with a lock means for inhibiting rotation of the stand. (E) The lock means is configured to also prohibit rotation of the motor. According to the features (d) and (e), a stable parking state after the rotation of the stand can be secured.

(F) The lock means is urged by a manual operation and released by an electric command.
(G) power transmission means for transmitting power from the motor to the rear wheels, and clutch means provided in a power transmission system of the power transmission means, wherein the clutch means receives a pedal force greater than a predetermined value. The connection is established when the pedal is present, and the connection is released when the pedaling force greater than the predetermined value is not applied. According to the features (f) and (g), when the bicycle is dismounted and moved backward, the motor does not rotate in reverse and the stand does not rotate.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a side view of a battery-assisted bicycle having a driving device according to the present invention. The body frame 2 of the battery-assisted bicycle includes a head pipe 21 located in front of the body.
And a down pipe 22 extending downward and rearward from the head pipe 21, and a seat post 23 rising upward from near the end of the down pipe 22. The connecting portion between the down pipe 22 and the seat post 23 and the peripheral portion thereof are covered by a resin cover 33 which is vertically divided into two parts and which is attached and detached.

A handle 27 is rotatably inserted into the upper part of the head pipe 21 via a handle post 27A.
At the lower part of the head pipe 21, a front fork 26 connected to the handle post 27A is supported. A front wheel WF is rotatably supported at the lower end of the front fork 26. The handle 27 is provided with a brake lever 27B. The operation of the brake lever 27B is transmitted to a brake device (not shown) of the rear wheel WR through the brake wire 39.

The seat post 23 has a seat 30 at its upper end.
Is slidably mounted and the height of the seat 30 is adjustable. Sheet 30
A battery 4 housed in a battery housing and attached to the vehicle body is provided below the seat post 23 and below the seat post 23. The battery 4 includes a plurality of battery cells, and is installed along the seat post 23 such that the longitudinal direction is substantially up and down.

An electric assist unit 1 as a driving device including an electric motor M for assisting pedaling is provided at a lower portion of the body frame 2 with a battery bracket 49 welded to the connecting portion 92 at the lower end of the down pipe 22 and the seat post 23. And a connecting portion 90 provided at the front of the bracket 49 and a connecting portion 90 at the rear of the bracket 49 are bolted and suspended. In the connecting portion 90, the chain stay 25 is fastened together with the electric auxiliary unit 1.

The electric auxiliary unit 1 includes a crankshaft 101
Is rotatably supported, and the drive sprocket 1 is connected to the crankshaft 101 via a connecting member (sleeve 73 and the like) described later.
3 are connected. The rotation of the crankshaft 101 is transmitted from the driving sprocket 13 to the rear sprocket 14 through the chain 6. The drive sprocket 13 and the rear sprocket 14 are used to enable regenerative power generation.
Rigid mounting, that is, mounting in which one of the two sprockets rotates in any direction and the other follows. Therefore, no one-way clutch is provided between the rear wheel WR and the rear sprocket 14 to connect the two only in one rotation direction.

A pedal 12 is supported at both left and right ends of the crankshaft 101 via a crank 11. A rear wheel WR as a driving wheel is supported between the ends of a pair of left and right chain stays 25 extending rearward from the electric auxiliary unit 1. A pair of left and right seat stays 24 is provided between the upper portion of the seat post 23 and the end of both chain stays 25.
Is provided. The driving sprocket 13 and the crankshaft 101 are coaxially arranged, and the driving sprocket 1
Reference numeral 3 indicates a pedaling force transmitted through the pedal 12 and the crank 11, and a motor M (the shaft of the motor M is the crankshaft 1).
(Parallel to 01) is transmitted by being combined with the pedaling force.

A power switch section 29 for connecting a power supply, that is, the battery 4, to the electric auxiliary unit 1 is provided near the head pipe 21 on the down pipe 22, and is turned on / off by a power key. The power switch 29 may be provided on the handle 27 in front of the handle post 27A. The power supply unit 1 can be turned on by a remote control switch using an infrared signal, for example. In this case, the power switch unit 29 is provided with a receiver for receiving an infrared signal transmitted from the remote control switch.

A motor M is provided at a lower rear portion of the electric auxiliary unit 1.
The stand shaft 5 is provided in parallel with the motor M. The stand shaft 5 is connected to the motor M via a gear device described later so as to be rotatable by the motor M. Stand shaft 5
Stands 34 are fixed to both ends of the. Stand 3
Reference numeral 4 denotes a so-called center stand type in which a pair of rod-like members project downward from the vehicle body to the left and right.

FIG. 4 is an enlarged view of a main part showing the vicinity of the stand 34. The stand 34 is fixed to the stand shaft 5 and swings according to the rotation of the stand shaft 5. The swing angle of the stand shaft 5 is regulated by the vertical wall surface 701 and the horizontal wall surface 702 of the casing 70 of the electric auxiliary unit 1.
A tension coil spring 35 is stretched between the stand 34 and the casing 70. The tension coil spring 35 acts to bias the stand 34 toward the wall surface 701 or 702. That is, when the stand 34 is raised, the stopper surface 34a formed on the hub of the stand 34 acts to abut the wall surface 701, and when the stand 34 is flipped backward, the stand 34 is attached to the wall surface 702 side. Energize to maintain that flipping attitude.
In addition, a sheet or block 36 of an anti-vibration rubber is attached to the wall surface 702 to reduce the shock when the stand 34 is flipped up.

FIG. 2 is a sectional view of the electric auxiliary unit 1, and FIG.
FIG. 3 is a view taken along the line AA in FIG. 2. The casing of the electric auxiliary unit 1 includes a main body 70, and a left cover 70L and a right cover 70R attached to both side surfaces thereof. The casing 70, the left cover 70L, and the right cover 70R are made of a resin molded product for weight reduction. Around the casing body 70, the down pipe 2
2 and connecting portions 90, 91, 92 of the battery bracket 49.
Hangers 90a, 91a, and 92a are formed, respectively. The main body 70 is provided with a bearing 71, and the right cover 70R is provided with a bearing 72. Bearing 71
The inner shaft of the bearing 72 is inscribed with a crankshaft 101, and the inner race of the bearing 72 is inscribed with a sleeve 73 which is coaxial with the crankshaft 101 and is slidably provided on the outer periphery of the crankshaft 101. That is, the crankshaft 101 is
And a bearing 72.

An assist gear 7 for transmitting the assisting force of the motor M to the driving sprocket 13 is provided on the sleeve 73.
6 is provided slidably in the circumferential direction of the sleeve 73. The assist gear 76 is preferably formed of a metal portion at the center, ie, the boss 74, and a helical gear made of resin from the viewpoint of weight reduction and quietness during rotation. A recess 7 which forms a part of a dog clutch is provided on a side surface of the assist gear 76.
6a are formed. A spline is formed on the sleeve 73, and the clutch plate 8 having a spline hole that fits the spline is formed on the sleeve 73.
6. Pressure plate 87 and drive sprocket 1
3 are fitted. The drive sprocket 13 is connected to the rear sprocket 14 by a chain 6.

The clutch plate 86 has the concave portion 76a
The projection 7 is provided on the surface facing the assist gear 76 so as to conform to
5 are provided. A spring washer 85 is interposed between the clutch plate 86 and the assist gear 76. Therefore, the clutch plate 86 is urged by the spring washer 85 in a direction away from the assist gear 76.

A pressure plate 87 is disposed on the back surface of the clutch plate 86, that is, on the surface opposite to the surface facing the assist gear 76. In the space between the pressure plate 87 and the right cover 70R, there is provided a plunger 88 which projects and retreats in a direction orthogonal to the pressure plate 87.
, A linear solenoid 89 is provided. The tip of the plunger 88 faces the pressure plate 87,
When the linear solenoid 89 is biased, the pressure plate 87 is pressed toward the clutch plate 86 to be deflected.

A gear 73a is formed at one end of the sleeve 73, that is, at an end opposite to the side on which the drive sprocket 13 is mounted. The gear 73a is a sun gear and three planetary gears are provided around its outer periphery. 77 are arranged. The planetary gear 77 is supported by a shaft 77 a erected on a support plate 102, and the support plate 102 is further supported by a crankshaft 101 via a one-way clutch 78. The planetary gear 77 meshes with an inner gear formed on the inner periphery of the pedaling force detection ring 79.

The pedaling force detecting ring 79 has arms 79a and 79b projecting from the outer periphery thereof.
The crankshaft 101 is provided with a tension spring 80 provided between the arm 79a and the main body 70 and a compression spring 81 provided between the arm 79b and the main body 70.
, Is urged in a direction (clockwise direction in the figure) opposite to the rotation direction during traveling. The compression spring 81 is provided to prevent the ring 79 from rattling. The arm 79b has a potentiometer 82 for detecting the displacement of the ring 79 in the rotation direction.
Is provided.

A pinion 83 fixed to the shaft of the motor M is engaged with the assist gear 76. The motor M is a three-phase brushless motor and has a neodymium (Nd-F
eB) a rotor 111 having a magnet pole 110;
A stator coil 112 provided on the outer periphery thereof; a rubber magnet ring 113 for magnetic pole sensors (in which N and S poles are alternately arranged to form a ring) provided on a side surface of the rotor 111; A Hall IC 115 disposed opposite to the ring 113 and attached to the substrate 114;
And a shaft 116 of the rotor 111. The shaft 116 is supported by a bearing 98 provided on the left cover 70L and a bearing 99 provided on the casing body 70.

A controller 100 including a driver FET and a capacitor for controlling the motor M is provided near the front of the vehicle body of the casing body 70, and power is supplied from the battery 4 to the stator coil 112 through the FET. The controller 100 operates the motor M according to the treading force detected by the potentiometer 82 as a treading force detector, and generates auxiliary power.

The casing body 70 and the covers 70L, 70
R is preferably made of a resin molded product from the viewpoint of weight reduction, but it is necessary to increase the strength around the bearing. Therefore, metal reinforcing members 105, 10 such as iron, aluminum, aluminum alloy, and copper alloy are provided around the bearing.
6,107 are arranged. In particular, the reinforcing members arranged in the casing body 70 are parts where large loads are expected, such as the bearing 71 of the crankshaft 101 and the bearing 99 of the motor shaft 116, and the hangers 90a, 91a, 92a serving as attachment members to the vehicle body. And reinforcing members of each part are connected to each other to form an integral reinforcing plate 1.
05 was formed. According to the reinforcing plate 105, each reinforcing member disposed around each bearing or hanger communicates with each other to further enhance the reinforcing effect.

The reinforcing plate 105 is not limited to one that connects all the reinforcing members around the bearing 71 and the bearing 99 and the hangers 90a, 91a and 92a. Among these reinforcing members, those that are close to each other, for example, the hanger 90a Connecting the reinforcing member around the bearing 99 and the reinforcing member around the bearing 99, or connecting the reinforcing member around the bearing 71 and one of the hanger 90a, 91a, 92a around the bearing 99. May be. The reinforcing members 105, 106, and 107 are preferably formed integrally with the casing 70 and the covers 70L and 70R during resin molding.

When the pedaling force is applied to the crankshaft 101 via the crank 11 in the electric auxiliary unit 1 having the above structure,
The crankshaft 101 rotates. The rotation of the crankshaft 101 is transmitted through the one-way clutch 78 to the support plate 102.
And the shaft 77a of the planetary gear 77 is connected to the sun gear 73a.
Around the sun gear 73 via the planetary gear 77.
a is rotated. As the sun gear 73a rotates, the drive sprocket 13 spline-coupled to the sleeve 73 rotates.

When a load is applied to the rear wheel WR, the pedal force detecting ring 79 rotates according to the magnitude of the load, and the amount of rotation is detected by a potentiometer 82. When the output of the potentiometer 82, that is, the output corresponding to the load, is larger than a predetermined value, the motor M is energized according to the magnitude of the load to generate auxiliary power. When the motor M is energized, the linear solenoid 89 is energized and the plunger 88
The clutch plate 86 is urged toward the assist gear 76 via the pressure plate 87, and the dog clutch including the convex portion 75 and the concave portion 76 a is connected to transmit auxiliary power to the sleeve 73. That is, the electric assist power is combined with the drive torque generated by the human power generated by the crankshaft 101 and transmitted to the drive sprocket 13.

The linear solenoid 89 may be energized other than when the pedaling force is large. For example, switch means for detecting a brake operation is provided, and when the brake operation is detected, the linear solenoid 89 is energized. Then, the clutch plate 86 is biased toward the assist gear 76, the dog clutch is engaged, and the assist gear 76 is rotated. Therefore, the rotation of the driving sprocket 13 during braking is transmitted to the pinion 83 through the sleeve 73 and the assist gear 76. When the pinion 83 rotates, an electromotive force is generated in the stator coil 112, and regenerative power generation is performed. The current generated by the power generation
0 is supplied to the battery 4 and the battery 4 is charged.

Next, the drive section of the stand 34 will be described. 5 is a cross-sectional view of a main part of a stand driving unit provided in a part of the electric auxiliary unit, and FIG. 6 is a view taken along the line BB of FIG. 5, and the same reference numerals as those in FIGS. Is shown. In FIGS. 5 and 6, a first stage gear 40 is rotatable only in one direction via a one-way clutch 38 on a shaft 37 supported at both ends by a casing 70 and a right cover 70R.
Is supported. The first gear 40 is driven by the pinion 83. If the pinion 83 is a helical gear, the first gear 40 is also a helical gear. A small gear 40a is provided integrally with the first stage gear 40,
An idle gear 42 supported by a shaft 41 meshes with the small gear 40a. The shaft 41 of the idle gear 42 is supported by a casing 70 via a bearing 43. The final stage gear 44 that meshes with the idle gear 42 is fixed or formed integrally with the output shaft, that is, the stand shaft 5. The stand shaft 5 is rotatably supported by a bearing 46 fitted to the casing 70 and a bearing 47 fitted to the right cover 70R. The bearing 47 is housed in the cap 48 and attached to the right cover 70R. Stand shaft 5
Stands 34, 34 are fixed to both ends.

The stand driving device is provided with a lock device for restricting the movement of the stand 34. The lock device is a cam 40b provided integrally with the first stage gear 40.
A lock pin 57 that engages with the notch 40c of the cam 40b, a plunger 51 of the linear solenoid 50 that engages with an intermediate portion of the lock pin 57, and a lever 52 that engages with the top of the lock pin 57. .

The lock pin 57 is slidably supported on the right cover 70R.
0b. Plunger 5
Numeral 1 is urged by a compression coil spring 53 in a direction protruding from the linear solenoid 50, and is drawn into the linear solenoid 50 when the linear solenoid 50 is energized. The lever 52 is connected to the right cover 70 by the pin 55.
It is swingably supported by R and engages with the lock pin 57 to define its position. The lever 52 can be operated manually.

The linear solenoid 50 can be configured to turn on / off the power by a remote control switch using an infrared signal. In this case, the remote control switch is preferably used in common with a remote control switch for turning on the power supply unit 1. FIG. 7 is a perspective view showing an example of the remote control switch. As shown in the figure, the remote control switch 56 is
Buttons 56a and 56b for instructing turning off, and a button 56c for giving an instruction to stand the stand 34 are provided. It is preset so that pressing the button 56c causes the motor M to rotate by a predetermined angle in the reverse rotation direction (the direction opposite to the rotation direction when the auxiliary force is applied). This scheduled angle is
This angle corresponds to the angle at which the stand 34 rotates and the stopper surface 34 a provided near the axis of the stand 34 comes into contact with the wall surface 701 of the casing 70.

In the stand driving unit having the above-described structure, after the bicycle is stopped, the remote control switch 56
When the button 56c is pressed, the motor M rotates in the reverse direction, the stand 34 rotates in the direction of arrow R in FIG. 6, and the motor M stops when rotated by the predetermined angle. At this stop position, the stopper surface 34a is in contact with the wall surface 701 as described above. The notch 40c of the cam 40b is set so as to be located at a position facing the tip of the lock pin 57 when the stand 34 stands.

In order to set up the stand 34, the motor M
When is rotated in the reverse direction, the linear solenoid 50 is urged, so that the lock pin 57 is retracted and disengaged from the cam 40b. Further, since the pedal is not depressed, no depressing force is applied, and the linear solenoid 89 for driving the dog clutch is not energized. Therefore, even if the motor M rotates, no auxiliary force for urging the driving sprocket 13 is generated. .

When the power is turned off by pressing the button 56b of the remote control switch 56 after the stand 34 stands up, the power supply to the linear solenoid 50 is also cut off, and the plunger 51 projects and is pressed by the lock pin 57. Here, when the lever 52 is manually operated and the lock pin 57 is pushed in, the tip of the lock pin 57 is
c, the tip of the plunger 51 is connected to the side of the lock pin 57 at that position, and the drive unit of the stand 34 is locked. At the time of this lock, the pinion 83 meshing with the gear 40 also cannot rotate, and the operation of applying the electric assist force is also locked.

When the power is turned on by pressing the button 56a of the remote control switch 56, the linear solenoid 50 is energized, the plunger 51 is retracted, and the engagement with the lock pin 57 is released. As a result, the lock pin 57
Is retracted, and the engagement of the cam 40b with the notch 40c is released. When the lock state by the lock pin 57 is released,
Since the stand 34 is rotatable, if the stand 34 is flipped up with a foot, the rear wheel WR is grounded and the bicycle can be run.

[0042]

As is apparent from the above description, according to the first to eighth aspects of the present invention, an electric assisted bicycle, which tends to have a large body weight, can be parked by an easy operation. In particular, according to the invention of claim 2, no special circuit means for reverse rotation control or rotation angle detection is unnecessary, and the structure can be simplified. According to the third aspect of the invention, it is possible to provide a simple configuration for preventing the power generated when the auxiliary force is generated from being transmitted to the stand. According to the fourth aspect of the present invention, it is possible to provide a compact drive unit integrated with a motor drive unit that generates an auxiliary force. According to the fifth and sixth aspects of the present invention, a stable parking state with the stand upright can be secured. Claim 7,
According to the eighth aspect of the present invention, the power assisting force is not transmitted to the rear wheels unless the vehicle is traveling, so that unnecessary power assist due to a malfunction can be avoided.

[Brief description of the drawings]

FIG. 1 is a side view of an electric assist bicycle according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of the electric auxiliary unit.

FIG. 3 is a sectional view taken along a line AA in FIG. 2;

FIG. 4 is a side view of a main part of a stand driving unit.

FIG. 5 is a sectional view of a main part of a stand driving unit.

FIG. 6 is a sectional view taken along a line BB in FIG. 4;

FIG. 7 is a perspective view of a remote control switch.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electric auxiliary unit, 2 ... Body frame, 4 ... Battery, 5 ... Stand axle, 13 ... Drive sprocket, 29 ... Power switch part, 34 ... Stand, 36
... vibration isolation block, 39 ... brake wire, 70 ... casing body, 70R ... right cover, 70L ... left cover, 40 ... initial gear, 40b cam, 44 ... output gear, 57 ... lock pin, 83 ... motor pinion 1
01: pedal crankshaft, 102: support plate,

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masashi Igarashi 1-4-1 Chuo, Wako-shi, Saitama Pref. Inside Honda R & D Co., Ltd. (72) Koji Sakagami 1-4-1 Chuo, Wako-shi, Saitama Inside Honda R & D Co., Ltd. (72) Inventor Toshiyuki Naga 1-4-1 Chuo, Wako-shi, Saitama Prefecture Inside Honda R & D Co., Ltd. (72) Tatsushi Akiba 1-4-1 Chuo, Wako-shi, Saitama Honda R & D Co., Ltd.

Claims (8)

[Claims] 1. An electric assist bicycle having a human-powered drive unit including a pedal crankshaft for transmitting treading force and a motor drive unit including a motor for generating auxiliary power combined with the human-powered drive unit, comprising: A motor-assisted bicycle comprising: a stand movably provided to allow a vehicle body to stand on itself by turning a predetermined angle; and stand driving means for rotating the stand by the predetermined angle by the motor. 2. The motor is a brushless motor,
The electric assist bicycle according to claim 1, wherein the stand is driven by rotation in a direction opposite to a rotation direction when the motor generates the auxiliary force. 3. The electric assist bicycle according to claim 2, wherein a power transmission system including a one-way clutch is provided in the stand driving means for transmitting only rotation in the reverse direction by the motor to the stand. 4. The electric assisted bicycle according to claim 1, wherein a rotating shaft of the stand is provided below the motor drive unit, and the stand drive unit is formed integrally with the motor drive unit. 5. The battery-assisted bicycle according to claim 1, wherein said stand driving means is provided with a lock means for inhibiting rotation of the stand. 6. The battery-assisted bicycle according to claim 5, wherein said locking means is configured to also inhibit rotation of said motor. 7. The battery-assisted bicycle according to claim 5, wherein the lock means is energized by a manual operation and is released by an electric command. 8. A power transmission device for transmitting power from the motor to a rear wheel, and a clutch device provided in a power transmission system of the power transmission device, wherein the clutch device has a pedaling force greater than a predetermined value. The electric assist bicycle according to any one of claims 1 to 7, wherein the electric assist bicycle is configured to be connected when the pedal is being applied, and to be released when the pedaling force greater than the predetermined value is not applied. .