HK1190122B - Electrical motor-assisted bicycle component mountable on a bicycle frame - Google Patents

Description

Assembly for electric power-assisted bicycle capable of being mounted on bicycle frame

The present application is a divisional application of an invention patent application having an application number of 200780052287.0, entitled "electric power assisted bicycle and component for electric power assisted bicycle mountable on a bicycle frame", entitled "new era technical research corporation and new era engineering limited company, 3, 28, 2007.

Technical Field

The present invention relates to an electric power-assisted bicycle that can travel by assisting pedaling force with electric power, and a module for an electric power-assisted bicycle that can be attached to a bicycle frame.

Background

Generally, an electric power-assisted bicycle that can travel by assisting a pedaling force with an electric power is provided with a resultant force mechanism that combines the pedaling force and the electric power. As an example of such a force combining mechanism, an electric power assisted bicycle having a force combining mechanism described in japanese unexamined patent publication No. 2002-362468 has been developed. As shown in fig. 3 of the publication, the electric power-assisted bicycle includes: the drive device includes a sprocket 2 rotatable to transmit a pedal force to a drive wheel, an auxiliary gear 30 rotatable coaxially with the sprocket 2, a drive unit outputting an electric force corresponding to the pedal force under a predetermined condition, a power sprocket 33 rotatable by the output electric force, and an auxiliary chain 32 interposed between the auxiliary gear 30 and the power sprocket 33. This technique has an advantage that the degree of freedom of installation of the resultant force mechanism is greatly increased, and a dedicated frame is not actually required.

Patent document 1: japanese unexamined patent publication No. 2002-362468

However, in the above-described conventional power combining mechanism, the main portion of the pedaling force sensor and the auxiliary drive unit are separate components, and therefore, there is room for improvement in terms of simplification of the mechanism and ease of attachment to the vehicle body frame.

Disclosure of Invention

The present invention has been made in view of the above problems, and an object of the present invention is to simplify an auxiliary power mechanism used for an electric power assisted bicycle and to facilitate mounting to a bicycle frame.

In order to solve the above problem, one embodiment of the present invention provides an electric power-assisted bicycle that can travel by assisting pedaling force with electric power, the electric power-assisted bicycle including: the power transmission device includes a sprocket rotatable to transmit a pedal force to a drive wheel, an electric power output mechanism outputting an electric power from an output shaft, an assist gear connected to the output shaft of the electric power output mechanism via a gear mechanism, and a connecting mechanism coaxially connecting the assist gear and the sprocket. Preferably, the power transmission device includes an elastic member attached to a power transmission path of the auxiliary gear, the link mechanism, and the sprocket. For example, the elastic member is provided in a region where at least either one of the sprocket and the auxiliary gear engages with the pin. One example of the connection mechanism is a pin that is attached to penetrate the auxiliary gear and the sprocket in the thickness direction. Preferably, the auxiliary gear is rotatably supported from the sprocket independently via a bearing.

According to the present invention, when the electric power output mechanism outputs the electric power corresponding to the pedaling force under the predetermined condition, the electric power is transmitted to the assist gear via the gear mechanism, and the assist gear is rotated. The electric power transmitted to the auxiliary gear is transmitted to the sprocket via a connecting mechanism such as a pin and an elastic mechanism. The sprocket transmits a resultant force of the pedaling force and the electromotive force to the driving wheel.

A preferred example of the gear mechanism includes: the electric power output mechanism includes a first gear interlocked with an output shaft of the electric power output mechanism, a second gear meshed with the first gear for speed reduction, and a third gear coaxially connected with the second gear and meshed with an auxiliary gear.

In this way, in the present invention, since power is transmitted from the auxiliary gear to the sprocket via the pin, the number of parts can be reduced to simplify the mechanism, and the structure that can be easily attached to the frame can be easily realized. Further, since the elastic member is attached to the power transmission path of the auxiliary gear, the link mechanism, and the sprocket, the power transmission can be realized very smoothly.

In another preferred aspect of the present invention, the electric power output mechanism and the gear mechanism are fixed to a common base, and the sprocket and the auxiliary gear are rotatably mounted on the common base. According to this aspect, the electric power output mechanism and the resultant force mechanism can be assembled in one assembly, and can be easily attached to the vehicle frame. In addition, the common base is processed, so that the assembly can be freely installed on any type of vehicle frame.

Preferably, at least a part of the electric power output mechanism and the gear mechanism is housed in a case connected to or integrally formed with the common base.

The electric bicycle according to another aspect of the present invention further includes a drive shaft that is rotatable by the pedaling force, and the drive shaft is rotatably supported on the common base. In this aspect, it is preferable that the drive shaft is housed in a boss connected to or integrally formed with the common base. In this case, it is preferable that the frame of the electric power-assisted bicycle has a shaft hole penetrating the boss. That is, the boss is formed to be able to penetrate through a shaft hole formed in the electric power bicycle. Thus, the shaft sleeve is inserted into the shaft hole, so that the integrated assembly of the electric power output mechanism and the resultant force mechanism can be easily attached to and detached from the vehicle body frame.

In the electric power-assisted bicycle according to the other aspect of the present invention, the sprocket is attached to the drive shaft via the one-way clutch, and the one-way clutch transmits only one-way rotation of the pedal force applied to the drive shaft to the sprocket. In this aspect, more preferably, the electric power-assisted bicycle includes a detection means for detecting a physical quantity of the one-way clutch that changes in accordance with the pedaling force, and a control means for controlling the electric power based on at least the physical quantity detected by the detection means. Thus, the electric power output mechanism and the resultant force mechanism cannot be assembled into an integrated unit as a whole by a simple mechanism.

On the other hand, the auxiliary gear is preferably rotatably mounted on the common base via a bearing. This enables stable transmission of the electric power to the sprocket.

Another aspect of the present invention relates to an assembly for an electric assist bicycle mountable to a bicycle frame. The assembly is formed by arranging at least the following components on a common base: the power transmission device includes a sprocket rotatable to transmit a pedal force to a drive wheel, an electric power output mechanism outputting an electric power for assisting the pedal force from an output shaft, an assist gear connected to the output shaft of the electric power output mechanism via a gear mechanism, and a connecting mechanism coaxially connecting the assist gear and the sprocket.

The objects and advantages of the present invention will be more clearly understood by referring to the preferred embodiments of the present invention described below.

Drawings

FIG. 1 is a schematic view of an electric bicycle of the present invention;

FIG. 2 is a schematic view of a control system for an electric bicycle of the present invention;

FIG. 3 is a view showing an assembly mounted on an electric power assisted bicycle according to an embodiment of the present invention, (a) is a side view, and (b) is a cross-sectional view;

FIG. 4 is a schematic view for explaining a step of mounting the component of an embodiment of the present invention to a bicycle frame, (a) is a perspective view seen from the right side when the component is mounted to the bicycle frame, (b) is an enlarged view of the component shown in FIG. 4 (a), (c) is a perspective view before the component is mounted to the bicycle frame, (d) is a perspective view when a part of the component is inserted into the bicycle frame, (e) is a perspective view when the component is fixed to the bicycle frame, and (f) is a perspective view seen from the left side when the component is mounted to the bicycle frame;

FIG. 5 is an exploded perspective view of the one-way clutch shown in FIG. 3;

fig. 6 is a view showing a state in which teeth and pawls of a one-way clutch (ratchet) are fitted to each other, for explaining a pedal force detection principle of the electric bicycle according to the present invention;

fig. 7 is a view showing an example of a rotation preventing mechanism for preventing relative rotation of the claw portion with respect to the drive shaft, where (a) is a plan view showing a general structure of the ball spline, (b) is a plan view showing a general structure of the spline, and (c) is a plan view showing a general structure of the key groove.

Description of the reference numerals

1 electric power-assisted bicycle

2 sprocket wheel

4 drive shaft

11 Assembly

12 chain

13 drive housing

14 micro-computer

15 amplifying circuit

17 accumulator

22 driving wheel (rear wheel)

30 auxiliary gear

37 electric motor

37a electric motor output shaft

38 first gear

40 Gear mechanism

42 second gear

45 third gear

50 common base

52 shaft sleeve

70 bearing

80 axle hole

99 one-way clutch

100 claw part

102 ratchet pawl

112 tooth part

114 ratchet teeth

123 pin

124 disc spring

126 strain gauge

129 elastic member

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

Fig. 1 is a schematic view showing an electric power assisted bicycle 1 according to a first embodiment of the present invention. As shown in the drawing, the electric bicycle 1 has a main frame portion made of a metal tube frame 3, as in a conventional bicycle, and a front wheel 20, a rear wheel 22, a handlebar 16, a seat 18, and the like are attached to the frame 3 in a well-known manner.

The drive shaft 4 is rotatably supported at the central lower portion of the body frame 3, and pedals 8L and 8R are attached to the left and right end portions of the body frame via crank levers 6L and 6R, respectively. The drive shaft 4 is coaxially attached with the sprocket 2 via a one-way clutch (99 in fig. 3 (b) described later) for transmitting only the rotation in the R direction corresponding to the vehicle body forward direction. A chain 12 that rotates cyclically is provided between the sprocket 2 and the rear wheel power mechanism 10 provided at the center of the rear wheel 22.

The electric power-assisted bicycle 1 of the present embodiment controls to assist the pedaling force at least by an assist ratio (assist power/pedaling force) determined by the vehicle body running speed and the pedaling force. In the present embodiment, the unit 11 as the auxiliary power mechanism performs control of the electric power-assisted bicycle and a resultant force operation of the electric power and the pedaling force.

The general structure of the control system of the electric power assisted bicycle 1 is shown in fig. 2. The control system of the electric bicycle 1 of the present embodiment includes: a microcomputer 14 for controlling the electronic processing of the whole bicycle, an electric motor 37 capable of performing PWM control, an amplifier circuit 15 directly connected to the microcomputer 14 for amplifying the power of the control signal, and a battery 17 connected to the amplifier circuit 15 for supplying power to the electric motor 37.

At least a rotation speed signal for calculating a running speed and strain gauge signals 1 and 2 for calculating a pedal force are input to the microcomputer 14. The mechanism for generating these signals will be described later. The microcomputer 14 calculates the running speed and the pedaling force from these input signals, and performs electronic processing for determining the assist ratio based on a prescribed algorithm. Then, the microcomputer 14 gives a command to the electric motor 37 to generate the assist power corresponding to the determined assist ratio, and thus sequentially outputs the PWM command corresponding to the assist power.

Next, a module 11 as an auxiliary power mechanism in the electric power assisted bicycle 1 will be described with reference to fig. 3 (a) and (b).

The assembly 11 shown in fig. 3 (a) and (b) has an auxiliary gear 30, an electric motor 37, and a gear mechanism 40, the auxiliary gear 30 being coaxially connected with the sprocket 2, the electric motor 37 outputting electric power, the gear mechanism 40 being for transmitting electric power from an output shaft 37a of the electric motor to the auxiliary gear 30 via a gear. Therefore, when the electric motor 37 rotates, its torque is supplied to the auxiliary gear 30 via the gear mechanism 40, and is directly transmitted to the sprocket 2 that is fixed with respect to the auxiliary gear 30 and rotates with the pedaling force. Thereby, a resultant force of the assist power and the pedaling force is realized.

The gear mechanism 40 includes a first gear 38 that is interlocked with the output shaft 37a of the electric motor 37, a second gear 42 that is meshed with the first gear 38 and used for speed reduction, and a third gear 45 that is coaxially connected to the second gear 42 and meshed with the auxiliary gear 30.

A so-called one-way clutch (not shown) is provided in the middle of a transmission path for transmitting the assist power from the electric motor 37 to the assist gear 30, and the clutch transmits the power only in one direction. The one-way clutch is configured and connected to transmit the assist power from the electric motor 37 to the assist gear 30, but does not transmit the torque from the assist gear 30 to the electric motor 37 in the opposite direction. When the electric motor 37 is not rotated, smooth operation is possible by the above-described one-way clutch, not shown, and at this time, the rotational load of the motor is not transmitted to the auxiliary gear 30.

The sprocket 2, the auxiliary gear 30, the electric motor 37, and the gear mechanism 40 are mounted on a common base 50. In addition, the electric motor 37 and the gear mechanism 49 are integrally fixed to the common base 50 so as not to move. The electric motor 37 and the first gear 38 and the second gear 42 in the gear mechanism 40 are covered by the drive case 13. The drive housing 13 is connected to the common base 50 or is formed integrally with the common base 50.

On the drive shaft 4, the sprocket 2 is rotatably mounted on the common base 50 via a one-way clutch 99. As described later, the one-way clutch 99 transmits only the rotation in the forward direction applied to the drive shaft 4 to the sprocket 2. The drive shaft 4 is rotatably supported in a sleeve 52, and the sleeve 52 is fixed to the vehicle body frame in a state of being inserted into a shaft hole 80 formed in the vehicle body frame. The bushing 52 is coupled to the common base 50 or is integrally formed with the common base 50.

The sprocket 2 and the auxiliary gear 30 are coaxially connected via pins 123 (provided at three places at 120-degree intervals in the example of fig. 3 (a)). Thereby, the electric power transmitted to the auxiliary gear 30 is transmitted to the sprocket 2 via the pin 123. As shown in fig. 3 (b), the pin 123 is attached to penetrate the auxiliary gear 30 and the sprocket 2 in the thickness direction. In the example of fig. 3 (b), the leg portion of the pin 123 is inserted into the hole portion of the auxiliary gear 30 and fixed, and the head portion of the pin 123 penetrates the hole formed in the sprocket 2, and the tip end of the pin 123 for preventing the falling-off has a diameter larger than the diameter of the hole.

Further, an elastic member 129 such as rubber is provided around the head portion and the shaft portion of the pin 123. That is, the elastic member is provided at the engagement area between the sprocket 2 and the pin 123. This absorbs the rattling of the auxiliary gear 30 and the sprocket 2, and the power can be transmitted between the auxiliary gear 30 and the sprocket 2 very smoothly.

The connection mechanism between the sprocket 2 and the auxiliary gear 30 is not limited to the illustrated pin. For example, a bolt may be used, or a leg portion of the pin 123 may be integrally formed on the auxiliary gear 30. The elastic member 129 may be provided on any power transmission path among the auxiliary gear 30, the pin 123, and the sprocket 2. For example, the engaging region between the auxiliary gear 30 and the pin 123 may be provided separately or additionally.

In addition, the auxiliary gear 30 is rotatably mounted on the common base 50 via a bearing 70 independently of the sprocket 2. This enables the auxiliary gear 30 to transmit power to the sprocket 2 more stably.

As described above, in the present embodiment, the sprocket 2, the auxiliary gear 30, the electric motor 37, the gear mechanism 40, and the drive shaft 4 are mounted on the common base 50, and the electric circuit of the control system shown in fig. 2 and a pedal force sensor described later are mounted inside the drive case 13 and the one-way clutch 99, respectively, whereby one unit 11 can be configured to assemble all the components necessary for the electric assist. This simplifies the entire auxiliary power mechanism, and also facilitates mounting of the unit 11 to the vehicle frame. It will be appreciated that the assembly 11 can be mounted to any type of vehicle frame by appropriate machining of the common base.

The step of mounting the assembly 11 of one embodiment of the present invention to a bicycle frame is described with reference to fig. 4. Fig. 4 (a) shows a perspective view from the right side when the module 11 is mounted to a bicycle frame, fig. 4 (b) shows an enlarged view of the module 11 shown in fig. 4 (a), and fig. 4 (f) shows a perspective view from the left side when the module 11 is mounted to a bicycle frame.

First, as shown in fig. 4 c, the drive shaft 4 of the unit 11 is inserted from one end of the shaft hole 80 in the direction of the arrow (covered with the sleeve 52). Next, as shown in fig. 4 (d), the unit 11 is inserted from the end portion on the opposite side of the shaft hole 80 until the front ends of the drive shaft 4 and the boss 52 project, and the mounting metal member 82 and the fastening metal member 84 are attached to the projecting front ends thereof. In the step of fig. 4 (b), the module 11 is provided with a pair of protruding portions in which bolt-engaging holes are formed at both ends, and the frame is provided with a pair of adjustment pieces タブ each having a bolt hole and extending in parallel.

Finally, as shown in fig. 4 (c), the fastening metal fitting 84 is fastened to and fixed to the distal end portions of the drive shaft 4 and the boss 52, and the distal end portion of the attachment metal fitting 82 fastened by the fastening metal fitting 84 is fixed by a bolt to the outside of the unit 11. Further, bolts are fastened from both end portions in bolt screw holes of the bulging portions disposed in the pair of adjustment pieces. As described above, the assembly 11 can be reliably and easily mounted on the vehicle frame.

(Pedal force detecting mechanism)

A pedal force detection mechanism for outputting the strain gauge signals 1, 2 will be described with reference to fig. 3 to 7, and the strain gauge signals 1, 2 are input to the microcomputer 14. The pedaling force detection mechanism of the present embodiment detects strain that varies with the deformation of the one-way clutch 99, which corresponds to the pedaling force.

As shown in fig. 3 (b), the sprocket 2 is axially supported by the drive shaft 4 via a one-way clutch 99. As shown in fig. 5, the one-way clutch 99 includes claw portions ( portions) 100 and tooth portions 112.

In the pawl portion 100, three ratchet pawls 102 are arranged at equal angular intervals in the circumferential direction on the second engagement surface 110 thereof. The ratchet pawl 102 is formed of a rigid body and is rotatable about an axis extending in a substantially radial direction along the second engagement surface 110. When no force is applied to the ratchet pawl 102, the ratchet pawl 102 is urged by the pawl-lifting spring ( slip-on スプリング) 104 such that the longitudinal direction thereof forms a predetermined angle (the equilibrium direction 160 in fig. 6) with the second engaging surface 110. As shown in FIG. 6, when pawl 102 is deflected in either the rising direction a or the falling direction b from equilibrium direction 160, pawl lift spring 104 exerts a small spring force on pawl 102 to deflect it back to equilibrium direction 160.

A claw portion hole 106 for receiving the drive shaft 4 is formed in the center of the claw portion 100, and the claw portion hole 106 also penetrates the cylindrical portion 103 protruding from the back surface 101 of the claw portion 100. On the back surface 101, a circular groove 155 (fig. 3 (b)) is formed on the outer circumference of the cylindrical portion 103, and a plurality of steel balls 152 are rotatably fitted into the circular groove 155. Thus, a bearing that receives a load in the axial direction and also serves as a sliding bearing is formed on the back surface 101.

The disc spring 124 passes through the cylindrical portion 103 in its central hole 127 and abuts the rear surface 101 of the pawl portion 100. At this time, the disc spring 124 is slidably contacted to the back surface via the steel ball 152, i.e., the load bearing, in a direction of resisting the pressing force from the claw portion 100 with an elastic force. Strain gauges 126 are provided on the surface of the disc spring 124 at two positions opposed to each other in a 180-degree positional relationship. The two strain gauges 126 are electrically connected to the microcomputer 14 via leads 128. More preferably, three or more strain gauges may be provided to the disc spring 124. At this time, it is preferable that the plurality of strain gauges are provided so as to be respectively located at rotationally symmetrical positions on the surface of the disc spring 124.

The belleville spring 124 is received in the inner bottom 132 of the bowl support 130. The support 130 has a support hole 133 for passing through the drive shaft 4 and a support cylindrical portion 134 projecting from the rear surface. The support cylindrical portion 134 is screwed to the inner wall of the cut screw of the vehicle body attachment portion 145, thereby fixing the support 130 to the vehicle body. A bearing 138 (see fig. 3 (b)) that supports loads from both the axial direction and the radial direction is engaged with the inner wall of the support cylindrical portion 134, and the bearing 130 is locked by a stopper slope 144 formed in the drive shaft 4. Similarly, since the bearing 139 is also attached to the opposite side of the drive shaft 4 (see fig. 4 (b)), the drive shaft 4 is rotatable with respect to the vehicle body.

First rotation preventing grooves 108 extending in the axial direction 5 are formed at four locations on the inner wall of the claw hole 106. Also in the outer wall portion of the drive shaft 4 which is in sliding contact with the inner wall of the claw hole 106, second rotation preventing grooves 140 are formed at four locations, and the second rotation preventing grooves 140 extend in the axial direction 5 so as to face the first rotation preventing grooves 108. As shown in fig. 7 (a), the first rotation prevention groove 108 and the second rotation prevention groove 140 facing the first rotation prevention groove form cylindrical grooves extending in the axial direction, and a plurality of steel balls 150 are accommodated in each cylindrical groove to fill the cylindrical grooves. Thereby, the pawl portion 100 can move in the axial direction with the minimum frictional resistance, and relative rotation with respect to the drive shaft 4 is prevented. The rotation preventing mechanism is configured as a ball spline, but another type of ball spline, for example, a circularly rotating ball spline, can be applied as the slidable rotation preventing mechanism.

As a method of attaching the pawl portion 100 to the drive shaft 4, a mechanism other than the ball spline of fig. 7 (a) may be employed. For example, as shown in fig. 7 (b), a key/spline (キースプライン) type is also applicable as the rotation prevention mechanism, and the key/spline type is a type in which a projection 140a extending in the axial direction is provided on the drive shaft 4, and a third rotation prevention groove 108a for accommodating the projection 140a is formed in the pawl portion 100. In fig. 7 (b), the protrusion 140a may be provided on the pawl 100 side and the third rotation prevention groove 108a may be provided on the drive shaft 4 side. As shown in fig. 7 c, a spline type may be applied as the rotation prevention mechanism, and the spline type is a rectangular parallelepiped type groove in which a fourth rotation prevention groove 108b extending in the axial direction and a fifth rotation prevention groove 140b facing the fourth rotation prevention groove 108b are provided in the claw portion 100 and the drive shaft 4, respectively, and the key plate キープレート is housed.

A plurality of ratchet teeth 114 for engaging with the ratchet pawl 102 are formed on the first engaging surface 121 of the tooth portion 112. The ratchet teeth 114 are constituted by a steeper inclined surface 118 and a gentler inclined surface 116 with respect to the first engaging surface 121, wherein the inclined surfaces 118 and 116 are different from each other in the circumferential direction of the tooth portion and are formed periodically.

The tooth portion 112 is slidably axially supported by the drive shaft 4 via a collar 111 such that the first engagement surface 121 faces the second engagement surface 110 of the pawl portion 100. At this time, pawl 102 engages ratchet teeth 112 (FIG. 6). That is, the drive shaft 4 is movably connected to the tooth portion 112 only via the engagement portion between the ratchet pawl 102 and the ratchet teeth 112. A washer 122 is fitted to an end 142 of the drive shaft 4 that passes through the tooth hole 120 via the collar 111, and the washer 122 prevents the tooth 112 from being disengaged outward in the axial direction (fig. 3 (b)). The sprocket 2 is immovably attached to the teeth 112 via a pin 123 (fig. 3 (b)), and the pedal shaft 146 is attached to the front end of the drive shaft 4. Thus, the ratchet teeth for coupling the drive shaft 4 and the sprocket 2 are completed, and only the rotation in the vehicle body advancing direction by the pedal force is transmitted to the sprocket 2.

Preferably, the biasing spring 136 is installed between the stopper slope 144 of the drive shaft 4 and the back surface 101 of the pawl 100. When the pedal depression force is equal to or less than a predetermined value (for example, substantially close to zero), the biasing spring 136 axially biases the claw portion 100 so as to generate a gap between the steel ball 152 accommodated in the rear surface 101 and the disc spring 124.

Next, the operation of the present pedaling force detection mechanism will be described.

When the driver applies a pedal depression force to the pedals 8R and 8L (fig. 1) to rotate the drive shaft 4 in the vehicle body forward direction, the rotation force is transmitted to the pawl portion 100 which is rotatably supported by the drive shaft 3 so as to be non-rotatable with respect to the drive shaft 3. At this time, as shown in fig. 6, the ratchet pawl 102 receives a force Fd corresponding to the pedal depression force from the pawl portion 100, and therefore the tip end thereof abuts on the steeper inclined surface 118 of the ratchet teeth of the tooth portion 112, and the force is transmitted to the ratchet teeth. Since the ratchet tooth portion 112 is connected with the sprocket 2, the front end portion of the ratchet pawl 102 receives the force Fp generated by the load for driving from the steeper slope 118. The ratchet pawl 102, which receives forces Fp and Fd in opposite directions from both ends thereof, rotates in the direction a and stands up. At this time, the ratchet pawl 102 rises, and the pawl portion 100 moves inward in the axial direction, and presses the disc spring 124 attached between the pawl portion 100 and the holder 130. The disc spring 124 acts on the claw portion 100 against the pressing force Fr. In a short time, this force Fr is in equilibrium with a force reflecting the pedal depression force that moves the pawl 100 in the axial direction. Accordingly, the stress strain of the disc spring 124, the gap between the pawl portion 100 and the tooth portion 112, the angle of the ratchet pawl 102 with respect to the second engagement surface 110, the position of the pawl portion 100 with respect to the vehicle body frame, the pressure pressing the disc spring 124, and the like become physical quantities reflecting the pedal depression force. Therefore, by detecting at least one of them, the pedaling force T can be estimated.

In the present embodiment, as an example, the stress strain of the disc spring 124 is detected. The microcomputer 14 performs at least an addition calculation (including an average calculation) of signals from the two strain gauges 126 provided to the disc spring 124. By averaging and measuring the stress strain amounts at a plurality of locations in this manner, even with the same pedaling force, the output variation can be increased and the disturbance component can be smoothed, so that the SN ratio can be improved and the pedaling force estimation accuracy can be further improved. The greater the number of strain gauges, the greater the effect.

Further, when the pedal depression force is equal to or less than a predetermined value, the biasing spring 136 causes a gap between the rear surface 101 of the claw 100 and the disc spring 124, and therefore, the steel ball 152 frequently collides with the disc spring 124 less frequently. Therefore, the disturbance component of the strain gauge signal can be reduced, and the stability of the pedal force detection and the electric power assist control can be improved.

Then, the microcomputer 14 calculates an auxiliary power Te for assistance to be applied based on at least the calculated pedaling force T, and calculates and outputs a control signal for commanding the electric motor 37 to perform rotational driving using the auxiliary power. Preferably, the microcomputer 14 converts the rotation speed signal detected by the rotation speed sensor 220 into a vehicle speed, determines an appropriate assist power Te based on two elements of the pedaling force T and the vehicle speed, and controls the electric motor 37 to generate the assist power Te.

The pedaling force detection mechanism of the present embodiment has more excellent effects as described below.

(1) Since the one-way clutch and the pedal force detection mechanism are realized by one mechanism, the number of parts can be reduced, and the reduction in size, weight, and cost can be realized.

(2) In addition to the above effects, the pedal force detection portion can be further reduced in size, weight, and cost by using a disc spring in which the load receiving unit and the load detection sensor are integrated and realizing two functions by one unit.

(3) As described in (1) and (2) above, the pedal force detection mechanism is reduced in size, weight, and simplification at a higher level, and therefore, the possibility of mounting the pedal force detection mechanism is further increased even in a general bicycle.

(4) For the reasons described in (1) and (2), it is possible to achieve an assist feeling that reduces the transmission loss of the load compared to the conventional mechanism and has good control responsiveness.

(5) For the reasons described in (1) and (2), the pedal does not move uselessly (until the sensor senses) as compared with the conventional mechanism (using a coil spring), and the feeling when the pedal is stepped on in the present embodiment is the same as the feeling when a general bicycle pedal is stepped on, compared with the feeling of elasticity in the conventional mechanism when the pedal is stepped on.

In addition, any one of the claws and teeth of the one-way clutch 99 may be attached to the sprocket, and the other may be attached to the drive shaft. For example, the pawl portion 100 may be attached to the sprocket side, the tooth portion 112 may be slidably and non-rotatably attached to the drive shaft 4, and the disc spring 124 may be pressed by the tooth portion 112.

In the above example, the stress strain of the disc spring is detected as the physical quantity relating to the pedal force, but the present invention is not limited to this, and any physical quantity that changes in accordance with the deformation of the one-way clutch 99 according to the pedal force can be detected. For example, as the physical quantity reflecting the pedaling force, the inclination of the ratchet pawl, the relative interval between the ratchet pawl portion and the ratchet tooth portion, the position of any one of the ratchet pawl portion and the ratchet tooth portion with respect to the vehicle body, the pressing force of the disc spring, and the like can be selected.

The type and shape of the elastic member disposed to oppose deformation of the one-way clutch 99 can be changed as desired. For example, a rubber elastic body can be used in addition to the disc spring and the coil spring. Further, although a strain gauge is exemplified as a mechanism for detecting stress strain, the mechanism is not limited to this as long as it can detect a physical quantity related to stress strain.

The embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and can be modified as appropriate within the scope of the present invention.

Claims (12)

1. An assembly for an electrically assisted bicycle mountable on a bicycle frame, the assembly characterized by,

at least the following components are arranged on the common base:

a sprocket that is rotatable and transmits a pedaling force to a drive wheel;

an electric power output mechanism that outputs an electric power for assisting a pedaling force from an output shaft;

an auxiliary gear connected to an output shaft of the electric power output mechanism via a gear mechanism; and

a connecting mechanism that coaxially connects the auxiliary gear and the sprocket;

a drive shaft housed in the sleeve so as to be rotated by the pedaling force;

the bushing is connected to or integrally formed with the common base.

2. The assembly of claim 1,

there is an elastic member mounted on a power transmission path of the auxiliary gear, the link mechanism, and the sprocket.

3. The assembly of claim 1,

the connecting mechanism is a pin or a bolt that is installed to penetrate the auxiliary gear and the sprocket in the thickness direction.

4. The assembly of claim 2,

the connecting mechanism is a pin or a bolt that is installed to penetrate the auxiliary gear and the sprocket in the thickness direction.

5. The assembly of claim 4,

the elastic member is provided in a region where at least one of the sprocket and the auxiliary gear engages with the pin or the bolt.

6. The assembly of claim 1,

the auxiliary gear is rotatably supported from the sprocket independently via a bearing.

7. The assembly of claim 1,

the gear mechanism has:

a first gear that is linked with an output shaft of the electric power output mechanism;

a second gear engaged with the first gear and used for speed reduction;

a third gear coaxially connected with the second gear and engaged with the auxiliary gear.

8. The assembly of claim 1,

the electric power output mechanism and the gear mechanism are fixed on the common base,

the sprocket and the auxiliary gear are rotatably mounted on the common base.

9. The assembly of claim 8,

at least a part of the electric power output mechanism and the gear mechanism is housed in a case connected to or integrally formed with the common base.

10. The assembly of claim 1,

the shaft hole is formed to penetrate through the shaft sleeve.

11. The assembly of claim 1,

the sprocket is mounted on the drive shaft via a one-way clutch that transmits only one-way rotation of the pedal force applied to the drive shaft to the sprocket.

12. The assembly of claim 11, having:

a detection means that detects a physical quantity of the one-way clutch that changes in accordance with the pedaling force;

a control mechanism that controls the electric power based on at least the physical quantity detected by the detection mechanism.