WO2001054966A1

WO2001054966A1 - Power-assisted bicycle, drive device, and drive sprocket

Info

Publication number: WO2001054966A1
Application number: PCT/JP2000/000338
Authority: WO
Inventors: Akihito Yoshiie
Original assignee: Sunstar Giken Kabushiki Kaisha; Uni-Sunstar B.V.
Priority date: 2000-01-25
Filing date: 2000-01-25
Publication date: 2001-08-02

Abstract

A power-assisted bicycle which is not different, in structure and appearance, substantially from a general bicycle and low in cost and weight, wherein a drive sprocket (11) is disposed at the part of a chain where a main sprocket (2) is engaged with the chain (12) so that the sprocket (11) is engaged with the chain together with the main sprocket (2) from the inside of the chain, one tooth (2a) of the main sprocket (2) and one tooth (11a) of the drive sprocket (11) are fitted together into one opening part (12b) of the chain, the pitch of the teeth (11a) of the drive sprocket (11) and the pitch of the teeth (2a) of the main sprocket (2) are formed to be almost the same and the rotating shafts of both sprockets are disposed roughly in parallel with each other in order to maintain this fitted condition at all times, and an electric motor (37) is connected to the rotating shaft (35a) of the drive sprocket (11) through a speed reduction mechanism (35) including a one-way clutch.

Description

Specification

TECHNICAL FIELD The technical field to which the present invention pertains

The present invention relates to a power assisted bicycle having a simple resultant force mechanism, a drive device that can be attached to the power assisted bicycle and assists pedaling force, and a drive sprocket for directly transmitting the torque of the drive device to a chain. About.

Background of the Invention

Conventionally, a power assisted bicycle has been implemented in which a driving means such as an electric motor is added to a bicycle, and the output of the driving means is controlled based on a change in pedaling force, thereby assisting running by human power. I have.

Generally, such a power-assisted bicycle is provided with a resultant device for synthesizing a pedal depressing force applied to a crankshaft and auxiliary power by an electric motor and transmitting the resultant force to driving wheels. This resultant device is usually included in a dedicated unit that integrates the torque detection mechanism, reduction gear, and drive mechanism. Further, as another method, there is a chain direct drive system in which a transmission gear of the electric assist power is directly connected to the chain to enable a resultant force with a pedal depression force.

However, the above-described resultant force device in the dedicated unit has a problem that the resultant force is added to the drive shaft by using a planetary gear device or a differential device, which results in a problem of complexity, increase in size and weight. Was. In addition, it is extremely difficult to install this special unit on ordinary bicycles, and in order to attach such a resultant force mechanism, the frame structure of the conventional bicycle must be changed, further increasing the cost and weight. And so on.

Further, in the conventional chain direct drive system described above, a state in which the transmission gear of the auxiliary power is hung on the chain can be seen, and there is a problem that the appearance of the bicycle may be impaired.

Summary of the Invention

The present invention has been made in view of the above-mentioned circumstances, and has a lighter and more compact resultant mechanism. Another object of the present invention is to provide a low-cost, lightweight, power-assisted bicycle that is substantially identical in structure and appearance to a general bicycle by making it invisible from the outside.

Another object of the present invention is to provide a power-assisted bicycle that solves the above-mentioned problems, and a drive device that can be attached to the power-assisted bicycle and assists pedaling force. The purpose is to provide a drive sprocket for transmitting torque directly to the chain.

In order to solve the above problems, the present invention provides a main sprocket having a chain, a detecting means for detecting a stepping torque by a pedaling force, a driving means capable of outputting an auxiliary torque for assisting a pedaling force, and a detecting means. A power assisted bicycle having control means for controlling the driving means based on the stepping torque obtained, further comprising a driving sprocket connected to a torque output shaft of the driving means, wherein the driving sprocket is The main sprocket is arranged so as to be fitted from the inside of the chain together with the main sprocket in a chain portion where the main sprocket is fitted to the chain.

Here, "fitting from the inside of the chain" means fitting from the inner region surrounded by the chain to the outside.

According to the present invention, when the control means controls the driving means based on the stepping torque detected by the detection means and outputs the auxiliary torque, the driving sprocket connected to the torque output of the driving means rotates. At this time, since the main sprocket and the driving sprocket are fitted to the chain, the main sprocket supplies the pedal depressing force to the chain, and the driving sprocket supplies the rotating force to the chain. As a result, the resultant force of the stepping torque and the auxiliary torque is achieved. As described above, according to the first aspect, the resultant force is realized by a simple mechanism of fitting the drive sprocket to the chain together with the main sprocket, so that the mechanism can be made lighter and more compact. . In addition, according to the first aspect, since the drive sprocket is fitted from the inside of the chain to the chain portion where the main sprocket is fitted to the chain, the drive sprocket appears to overlap the main sprocket. Thus the conventional switch Compared with the direct drive system, there is no risk of damaging the appearance of the bicycle. Most preferably, it is located axially inside the driving sprocket / Λ main sprocket. As a result, when viewed from outside the bicycle, the drive sprocket is hidden by the main sprocket. It is also preferable from a mechanical point of view.

Also preferably, the main sprocket is thinner than normal so that the opening in the chain has a normal width and both the teeth of the main sprocket and the teeth of the drive sprocket can enter the opening together. It is good to form. As a result, the cost can be reduced by using a conventional chain, and the weight of the main sprocket and thus the bicycle can be reduced.

Further, the teeth of the main sprocket and the teeth of the moving sprocket that have entered the opening of the chain may be formed so as to be symmetrically arranged in the opening. As a result, the stepping torque and the auxiliary torque are transmitted to the chain in a well-balanced manner. To properly fit the drive sprocket to the chain, the teeth of the drive sprocket are formed at substantially the same pitch as the teeth of the main sprocket, and the rotation axis is arranged substantially parallel to the rotation axis of the main sprocket. Is done. In addition, the drive sprocket has a diameter that is less than the diameter of the main sprocket so that it does not contact the drive shaft of the main sprocket.

Formed smaller than one half.

It is preferable that the main sprocket includes a central shaft portion and an outer peripheral portion provided with a plurality of teeth, and is formed so that the central shaft portion projects outward in the axial direction with respect to the outer peripheral portion. Accordingly, when the driving sprocket is arranged on the inner side in the axial direction, a space for accommodating the projecting portion on the outer side in the axial direction of the driving sprocket can be secured.

The power source of the driving means may be arbitrary, but it is preferable to use an electric motor. Most preferably, the driving means includes a one-way clutch that transmits power from the driving side to the driven side and does not transmit power in the opposite direction. Through this one-way clutch, light operation is always possible without transmitting the load of the driving means during non-driving to the chain.

The detection means of the present invention can employ any means. However, in order to sufficiently exert the effects of the present invention, a large coil sprocket not used in general bicycles as in the prior art is used. Detection means that does not require a separate component such as a ring is more preferable.

Therefore, another aspect of the present invention provides a one-way clutch means interposed between the drive shaft and the main sprocket for transmitting only the rotation of the drive shaft in the vehicle body forward direction to the main sprocket. Further, the detecting means detects a distortion displacement amount based on the deformation of the one-way clutch means caused by the pedal depression force, and the control means controls the driving means based on the detected distortion displacement amount.

Here, the strain displacement に due to the deformation of the one-way clutch means is the strain ffi and Z or the displacement M of the one-way clutch means itself or other members caused by the deformation of the one-way clutch. This means that it changes according to the magnitude of the stepping torque. According to this aspect, since the stepping torque can be detected from the amount of displacement of the clutch, which is indispensable for the rotation i, it is not necessary to use separate rest parts such as a large coil spring, and the rotation φ is small and light. Can be achieved.

The one-way clutch means is resiliently displaced in the 応じ direction in accordance with the pedaling force, and the detecting means detects the displacement in the 蚰 direction of the one-way clutch means as a strain displacement: ^. Good. For example, the one-way clutch means can be a ratchet gear. Further, the detection means may be a position sensor fixed to the solid frame.

Further, as still another aspect of the detecting means, the detecting means further includes a holding means having "sprocket holding" II '. Only the holding means may detect the displacement jit. On the other hand, it is preferable that the '1 clutch means be displaced so as to generate a stress in the axial direction of the drive shaft with respect to the lower holding stage when the drive shaft is rotated by pedal force. Further, the detection means can be configured as a strain gauge which is attached to the meta of the holding means and detects stress distortion of the meta.

Furthermore, the drive means is good preferable to be made contact ^'1 f as a single Yunitto that we millet in the housing. This single unit drive: 1¾ means can be easily and detachably attached to the frame of the power assist rotation 4: ':.

As described above, according to the present invention, a general を: 1 turn and a substantially one frame structure can be realized. It is possible to configure a power assisted bicycle having the above.

According to another aspect of the present invention, there is provided an auxiliary torque that can be attached to a bicycle that transmits pedal depression force to driving wheels via a main sprocket and a chain installed on the main sprocket, and an auxiliary torque for assisting the pedal depression force. A drive sprocket is connected to a torque output shaft of the drive device, and the drive sprocket has a front sprocket when the drive device is mounted on the bicycle. It is provided as a drive device formed so as to be able to be fitted from the inside of the chain together with the main sprocket to a chain portion to be fitted to the chain.

Still another aspect of the present invention is a driving sprocket formed so as to be connectable to a torque output shaft of driving means mounted on a bicycle, wherein the bicycle is a pedal via a main sprocket and a chain mounted on the main sprocket. The driving means can transmit a pedaling force to driving wheels, and the driving means can output an auxiliary torque for assisting the pedaling force. When the driving sprocket is connected to a torque output shaft of the driving means, the main sprocket A drive sprocket is provided on a portion of the chain where the slot is fitted to the chain so as to be fitted together with the main sprocket from the inside of the chain. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic diagram of a power assist tli transfer according to the present invention.

FIGS. 2A and 2B are views showing a resultant force and a driving mechanism of the electric assist bicycle according to the first embodiment of the present invention, wherein FIG. 2A is an enlarged front view near a sprocket, and FIG. 2B is a sectional view thereof.

FIGS. 3A and 3B are views showing a state in which the main sprocket and the driving sprocket according to the first embodiment of the present invention are fitted. FIG. 3A is a partially sectional side view, and FIG. It is the front view seen.

FIG. 4 is a block diagram illustrating an outline of an electric assist bicycle including a torque detection mechanism according to a second embodiment of the present invention.

FIG. 5 is a front view and a side view in a state where a main sprocket and a ratchet gear used in the electric assist bicycle according to the second embodiment are fitted.

Fig. 6 is a schematic perspective view of the state where the main sprocket and the ratchet teeth are disassembled. It is.

FIG. 7 is a schematic perspective view showing a state in which a sprocket and a ratchet gear are fitted to explain the axial displacement of the ratchet teeth.

FIG. 8 is a side sectional view of a sprocket and a driving means, showing a torque detecting mechanism according to a third embodiment of the present invention. Preferred embodiments of the invention

Hereinafter, the power assist rotation 1 according to each embodiment of the present invention will be described with reference to the drawings. Note that the power assisted bicycle described below is described as an electric assist bicycle that provides an auxiliary torque by an electric motor.

(First embodiment)

FIG. 1 shows an outline of the electric assist rotation: Φ: 1 according to the first embodiment of the present invention. As shown in the figure, the main skeleton portion of the electric assist bicycle 1 is formed of a metal frame 3 made of a metal tube, similar to a normal bicycle, and the rest frame 3 has a front wheel 20. , A rear wheel 22, a handle 16 and a saddle 18 are mounted in a known manner.

A drive shaft 4 is supported on the lower part of the center of the body frame 3 by a shaft fe [i ΐ:], and pedals 8 L and 8 R are provided on both left and right ends thereof through crank rods 6 L and 6 R. Each is installed. The main sprocket 2 is coaxially mounted on the drive shaft 4 via a one-way clutch (71 in Fig. 2 (b)) for transmitting only rotation in the R direction corresponding to the resting sleep direction. Have been. An endlessly rotating chain 12 is provided between the main sprocket 2 and a rear wheel power mechanism 10 provided at the center of the rear wheel 22.

Next, a combined mechanism of the auxiliary torque and the stepping torque in the electric assist bicycle 1 will be described.

Fig. 2 (a) shows an enlarged front view of the vicinity of the main sprocket 2 on the front side viewed from the outside of the bicycle (axially outside), and Fig. 3 (b) shows the rear side (axially inside) of the bicycle. The figure is shown. As shown in these figures, the main sprocket 2 is The drive sprocket 11 and the main sprocket 2 are arranged so as to be fitted from the inside of the chain (the side of the area 1IH below the chain) in the part of the chain where the shaft is fitted. As can be seen from the figure, the drive sprocket 11 is formed to have a diameter smaller than half the diameter of the main sprocket 2 so as not to contact the drive shaft 4. For example, when the outer diameter of the main sprocket 2 is about 134 mm, as an example, the outer diameter of the driving sprocket 11 is made about 38 mm.

As seen from the outside of the bicycle, the driving sprocket 11 is entirely hidden inside the main sprocket 2 in the axial direction, as shown in Fig. 2 (a), and partially from the hole in the crab main sprocket 2. You can only see it.

In order to show how the drive sprocket 11 and the main sprocket 2 are fitted to the chain 12, FIG. 3 (a) is a partial sectional view taken along the line X—X ′ in FIG. 3 (b). ). As shown in the figure, one opening 1 2b of the chain link (roller link or pin link) 12a has one tooth 2a of the main sprocket 2 and one tooth 1 of the driving sprocket 11 1a is fitted together. In order to maintain this fitting state, the spacing (pitch) between the adjacent teeth 11a of the driving sprocket 11 and the pitch of the teeth 2a of the main sprocket 2 are substantially the same. Preferably, the main sprocket 2 and the driving sprocket 1 are arranged such that the teeth 2a and the teeth 11a are substantially symmetric with respect to the virtual line 12c passing substantially at the center of the link opening 12b. 1 should be formed.

As shown in FIG. 2 (b) which is a cross-sectional view of FIG. 2 (a), the drive sprocket 11 is operatively connected to the drive unit 13 via a drive shaft 35a extending parallel to the drive shaft 4. Linked to In addition, since the central shaft of the main sprocket 2 is formed so as to protrude outward in the axial direction with respect to the outer peripheral portion provided with the teeth (in the illustrated example, two stages are provided), the driving sprocket 11 It can be seen that it can be properly fitted to the chain 12 together with the main sprocket 2 without hitting the back surface of the chain. As an example, the central shaft portion of the main sprocket 2 is stepped by about 9.4 mm with respect to the outer peripheral portion thereof so as to protrude axially outward.

The drive unit 13 is mounted on a frame that is also provided on ordinary bicycles. An electric motor 37 supplied by a battery (not shown) and a deceleration mechanism 35 that reduces the rotation of this motor and transmits it to the drive shaft 35a of the drive sprocket 11 Including. A so-called one-way clutch that transmits power only in one direction is provided in the transmission path of the auxiliary torque in the speed reduction mechanism 35. This one-way clutch is configured and connected to transmit the auxiliary torque from the electric motor 37 to the drive sprocket 11 in the opposite direction, that is, to transmit no torque from the drive sprocket to the speed reduction mechanism 35. You. As a result, the load of the electric motor 37 at the time of non-driving is not transmitted to the chain 12 so that light driving can be always performed.

The auxiliary unit is driven by the drive unit 13! When the sprocket 11 is supplied, the teeth 11a of the sprocket 11 and the teeth 2a of the main sprocket 2 together with the link opening of the chain 1 2 12b are sequentially fitted, whereby the combined torque of the auxiliary torque and the depressed torque is achieved.

As described above, in the embodiment of i1, since the driving force sprocket 11 fitted to the chain 12 together with the main sprocket 2 forms the resultant force device, as shown in FIG. A simple drive unit can be used as a separate single drive unit 13 with almost no change in structure. As a result, it is possible to reduce the weight of the electric assist rotation 1 and reduce the cost. Preferably, the link of chain 12 shown in Fig. 3 is opened to the width of 1 邰 1 2b while the link is open. It is better to reduce the thickness (for example, about 1.6 mm). At this time, it is preferable that the thickness of the tooth portion of the drive sprocket 11 is formed to be substantially the same as the thickness of the plate of the main sprocket 2. As a result, the weight of the sprocket 2 and the driving sprocket 11 and thus the electric assist bicycle 1 can be further reduced.

In addition, in the first embodiment, as shown in FIG. 2 (a), there is no risk of spoiling the appearance of the rotation Φ because the 3rd sprocket 11 is hidden behind the main sprocket 2 and cannot be seen from outside the bicycle. There is an advantage.

(Second embodiment) In the first embodiment, the torque detecting mechanism is optional. However, it is more preferable that the torque detecting mechanism be mounted without changing the conventional bicycle structure. In order to realize this, in the second embodiment, the torque is detected based on the shaft displacement of the one-way clutch interposed between the main sprocket and the drive shaft according to the torque. The second embodiment will be described below with reference to FIGS. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 5 shows a front view of the main sprocket 2 b and the ratchet gear 39 attached thereto, and a main sprocket 2 b and a ratchet gear 3 taken along the line SS ′ of the front view. Nine cutaway views are shown. As shown in the front view, the main sprocket 2 b has a plurality of teeth 24 for fitting with the chain 12 over the outer periphery of the rigid body part 38 and a space between adjacent teeth. In the center of the body part 38, a hole 41 for allowing the drive shaft 4 to penetrate, and a cylindrical stopper 46 for surrounding the hole 41 with ffl are formed. ing.

The ratchet gears 39 are fixed to the body part 38 of the main sprocket 2b at equal distances from the center of the sprocket (corresponding to the drive axis 5 in the figure). 0, and ratchet teeth 43 arranged on one side of the main sprocket 2b so as to be fitted to the ratchet piece.

The sectional side view of FIG. 5 shows a state where the main sprocket 2 b and the ratchet gear 39 are attached to the drive shaft 4. According to the drawing, a drive shaft 42 fixed around the drive shaft 4 so as not to move relative to the drive shaft is provided concentrically with the drive shaft. A pedestal 45 having a cylindrical shaft surface substantially parallel to the wire 5 is formed around the outer periphery of the drive shaft 42. The main sprocket 2b and the ratchet teeth 43 are arranged on the pedestal 45 in an engaged state. The main sprocket 2b can rotate independently of the drive shaft 42 in the pedestal 45 in the direction in which the clutch of the ratchet gear 39 does not act, and the ratchet teeth 43 are described later. Is fixed to the drive shaft 42.

Here, the engagement state of the main sprocket 2b and the ratchet teeth 43 and the clutch function will be conceptually described with reference to FIGS. FIG. 6 is a schematic perspective view showing a state where the main sprocket 2b and the ratchet teeth 43 are disassembled. As shown in the figure, the ratchet piece 40 is formed as a claw-shaped member obtained by bending a long and thin metal plate having elasticity, and a tip portion 40a of the claw-shaped member has a body portion 3 of the main sprocket 2b. The rear portion 40b is fixed to the body portion 38 by welding or the like so as to form a certain angle of inclination with respect to 8.

The ratchet tooth portion 43 has a disc portion 60 having a flat surface, and the disc portion 60 on the side facing the sprocket face has an entire circumference along its outer periphery. A plurality of teeth 44 for engaging with the ratchet piece 40 are formed on the upper surface. Each tooth 44 has a gentler slope 44a and a steeper slope 44b, respectively. Further, a cylindrical center shaft 54 extending in the axial direction is provided at the center of the disc portion 60 so as to protrude outward from the plane of the disc portion. An opening 57 for receiving a drive shaft 42 provided around the drive shaft 4 is penetrated. Also, inside the center shaft 54 on the opposite side of the disc portion 60 toward the sprocket surface, a flat detent portion 5 is provided so as to bridge the diameter of the opening portion 57. 2 is fixedly connected to the inner wall of the shaft. Further, a coil spring 50 is inserted into the center shaft 54, and one end of the coil spring 50 is in contact with the detent part 52, and the other end is not shown in the drawing. It is fixed to the shaft 42.

In the engagement state of the main sprocket 2b and the ratchet teeth 43, as shown in FIG. 7, the tip 40a of the ratchet piece 40 is formed by the adjacent slopes 44a and 44b. It penetrates into the defined recess, and its leading edge abuts against the steeper slope 44b. The opening 57 of the center shaft 54 receives the drive shaft 42. At this time, although not shown, the detent portion 52 is inserted into a longer slot 58 formed to penetrate the drive shaft 42 along the axial direction of the shaft. I have. As a result, the ratchet teeth 43 do not rotate with respect to the drive shaft 42, but rotate with the drive shaft 4 which is rotated by the depressed torque. Also, since the axial width of the detent portion 52 is smaller than the length of the slot 58, the detent portion 52 is connected to the slot 58. Slidable axially along. At this time, since the detent part 52 is urged by the coil panel 50 in the direction toward the main sprocket 2b, the leading end portion of the ratchet piece 40 engages with the ratchet tooth part 43. Locked at height.

As shown in the lower part of Fig. 7, when the drive shaft 42 rotates in the R direction corresponding to the forward direction of the bicycle 1, the foremost part of the ratchet piece 40 becomes the steeper slope 44b of the teeth 44. Since it does not slide along the slope when it abuts, the ratchet teeth 43 and the main sprocket 2b rotate in the R direction together with the drive shaft 42. On the other hand, when the drive shaft 42 rotates in the direction opposite to the R direction, the rear surface of the front end portion 40a comes into contact with the gentler slope 44a, so that it is not locked and follows the slope. The shaft of the drive shaft 42 does not transmit to the main sprocket 2b. This is the principle of the ratchet gear 39-one way clutch.

When the rotation of the drive shaft 42 in the R direction is transmitted to the main sprocket 2b via the ratchet teeth 43, as shown in the lower diagram of FIG. 7, the rotation received from the steeper shaft 44b. A ratchet piece 40 with elasticity against the force rises. For this reason, the ratchet teeth portion 43 is further away from the main sprocket 2b while resisting the urging force of the coil spring 50 from the normal position I | ll (| ¾14, position 48a in FIG. 5). As shown in the figure, the shaft is displaced in the axial direction, and stops at the position where the rotational force due to the pedal depression force and the elastic force of the ratchet piece 40 are balanced (positions 48b in FIGS. 4 and 5). When the stepping torque is reduced, the rotational force received from the steeper slopes 4 4 b becomes weaker, and the ratchet piece 40 tries to return to its original height due to its elasticity, and at the same time, is urged downward by the coil panel 50. The ratchet teeth 43 are displaced in the axial direction so as to approach the main sprocket 2b. Thus, the axial displacement of the ratchet teeth 43 (FIG. 7) reflects the magnitude of the stepping torque.

In order to detect the axial displacement of the ratchet teeth 43, as shown in FIG. 4, a position sensor 34 for detecting the axial distance from a predetermined position to the disc 60 of the ratchet teeth 43 is provided. Installed on the body frame. The position sensor 34 is mounted, for example, so as to move in the axial direction according to the axial displacement of the disk portion 60. A detection body made of a magnetic material such as an electromagnet, a coil disposed near the detection body, and a detection circuit capable of electrically detecting a change in the inductance of the coil as a change in impedance. This can be achieved by In this configuration, the detection object approaches or moves away from the coil according to the amount of axial displacement of the ratchet teeth 43, but the inductance of the coil changes according to the distance between the detection object and the coil. By detecting the change with the detection circuit, the distance 1 in the shaft direction up to the ratchet teeth 43 can be calculated. Of course, any other type of sensor may be used as long as the axial distance or the displacement L of the ratchet teeth 43 can be detected, and some sensors may be arranged in the ratchet gear 39. Can also. The output terminal of the position sensor 34 is connected to a controller 14 for receiving the detection from the sensor. The controller 14 can be realized by a so-called microcomputer or the like, and has an arithmetic function for calculating the value of the stepping-in torque based on the received detection about the separation of the axis j! Tfi.

As in the first embodiment, the driving force sprocket 11 and the drive sprocket 11 that fits into the link opening 12 b of the chain 12 together with the proket 2 b It is sharpened by driving means 13 for driving this. The electric motor 37 is electrically connected to the controller 14, and its rotation torque is controlled by a control signal from the controller 14.

Next, Sakugawa according to the second embodiment of the present invention will be described.

When the passenger applies pedal pressure to the pedals 8 R and 8 L and turns the drive 'Ι'ϊΙΐ 4 in the R direction, the detents 5 2 make the drive' | ll 4 non-rotatable ίΙ'ΛΪί '. The ratchet teeth 43 rotate together with the drive shaft 4, and the pulling force from the chain 12 acts as a load via the ratchet piece 40 engaged with the teeth 44 4: sprocket 2 Apply stepping torque to b. At this time, the ratchet piece 40 having a positive characteristic is piled up by the rotational force received from the steeper clinch 44 b of the ratchet tooth, and the ratchet tooth portion 43 is placed in the normal axial position. (Position 48a in Fig. 5) displaces in the axial direction away from the main sprocket 2b while resisting the biasing force of the coil spring 50, and the rotational force due to the pedal depressing force and the ratchet piece 40 Balance with elastic force At the position (position 4 8 b in Fig. 5).

The position sensor 34 in Fig. 4 constantly detects the axial distance from the fixed position to the disc 60 of the ratchet teeth 43 and sends the detection signal (corresponding to position 48b) to the controller. Communicate to 14. The controller 14 calculates the difference between the position 48a of the ratchet teeth 43 when the stepping torque previously stored in the internal memory is not applied and the position 48b indicated by the received detection signal. Is calculated to obtain the axial displacement amount. Since the axial displacement A L increases as the stepping torque increases, the controller 14 can calculate the value of the stepping torque from the correspondence between the two. This can be realized, for example, by experimentally determining the relationship between the axial displacement amount and the stepping torque in advance and storing a reference table representing this relationship in the internal memory of the controller 14.

Next, the controller 14 determines an auxiliary torque Te to be applied (for example, substantially the same as the stepping torque T) based on the calculated stepping torque T, and controls the electric motor to rotate the auxiliary torque. Calculates and outputs the control signal to command 37. For example, in the case of electric assist control in which S is also simple, when the calculated stepping torque becomes a predetermined value or more, the electric motor 37 is turned on and a predetermined ratio to the stepping torque (for example, the stepping torque T is substantially Outputs a motor control signal that commands the auxiliary torque to maintain the same), and outputs a motor control signal that turns off the electric motor otherwise. In this case, the electric motor 37 may be turned on only when the value becomes a certain value or more by directly using the axial displacement itself.

When the electric motor 37 is turned on and rotated, the torque is transmitted to the drive sprocket 11 via the reduction mechanism 35, and the teeth 11a of the drive sprocket 11 Together with the teeth 2a of b, they are sequentially fitted into the link openings 12b of the chain 12, whereby the auxiliary torque is combined with the stepping torque. As described above, the auxiliary torque is applied under the condition in which the stepping torque is considered to be equal to or more than a certain value, so that the turning can be easily performed.

As described above, in the second embodiment, the same effects as those of the first embodiment can be obtained, and the torque can be obtained based on the axial displacement of the ratchet gear, which is required for a general bicycle. Since the torque is calculated, the space and weight of the torque detection mechanism can be significantly reduced.

Further, in the second embodiment, the elastic displacement portion of the torque detecting mechanism is integrally included in the ratchet gear, and the driving sprocket 11 and the driving unit 13 constitute a resultant and a driving mechanism. There is almost no need to change the frame structure of the conventional vehicle body, and it is possible to further reduce the size, weight, simplification, and cost of the electric assist bicycle.

(Third embodiment)

FIG. 8 shows an alternative torque detection mechanism as a third embodiment. Note that, except for the torque detection mechanism, which is the same as that of the first embodiment, a detailed description is omitted, and the same reference numerals are given to the same components.

As shown in FIG. 8, the torque detection mechanism according to the third embodiment is provided with a sprocket 2c having a cylindrical housing portion 82 at the center thereof. The cylindrical housing portion 82 projects cylindrically on one plate surface side of the sprocket 2c and is concave on the other plate side. The sprocket 2c is arranged so that the concave portion of the cylindrical housing portion 82 faces the pedal 侧, and the concave portion only rotates in the forward direction, from its drive side to its driven side. A one-way clutch 72 that is transmitted to the vehicle is accommodated. On the other hand, the driven side portion of the clutch 72 is fixedly and quickly connected to the engagement portion with the concave portion of the cylindrical housing portion 82 so that the rotation only in the R direction is transmitted to the sprocket 2c. The driven side is fixedly connected to the drive shaft 4.

In this one-way clutch 72, the driven side 4 of the one-way clutch 72 is displaced according to the magnitude of the stepping torque when the drive shaft 4 rotates in the R direction and the rotational force is transmitted to the sprocket 2c. A clutch of the type displaced axially by the amount toward the sprocket side is selected. An example is the ratchet gear type one-way clutch of the second embodiment.

On the other hand, on the inner side of the sprocket 2 c on the opposite side, a bearing 74 is arranged around the protruding portion of the cylindrical housing portion 82, and the cylindrical housing portion is held from the periphery of the side surface. I have. The bearing 74 supports both axial and radial loads ffi. Preferably. Further, an elastic metal truncated cone-shaped dish panel 76 holds the bearing 74 so as to cover the outer periphery of the bearing 74, and the dish panel 76 is a rigid support table 78. And is fixed to the vehicle body via. That is, the sprocket 2c is elastically held on the side opposite to the one-way clutch 72 so as to be rotatable with respect to the vehicle body. As is apparent from FIG. 8 (b), when the axial width of the one-way clutch 72 and the axial width of the countersink 76 are projected onto the center axis of the drive shaft 4, they overlap each other at that axial position. It can be seen that it has a region.

Also, a strain gauge 80 for detecting strain on the dish panel due to applied stress is attached to the dish panel 76, and the strain gauge 80 is connected to a controller 14 (see FIG. 4). I have. This strain gauge 80 can be formed of, for example, a thin gold bending resistance element. In the case of this thin-film metal resistor, a thin oxide film insulating scrap is provided on the surface of the mirror-finished mi panel 76, and a resistor consisting of multiple elements is bridged on it by sputtering or other technique. It is formed in a shape. The controller 14 can detect the magnitude of the stress by detecting a change in the resistance of the bridge element due to the stress and strain applied to the disc spring # 6. The strain gauge 80 is preferably installed in a place where the counter panel 76 is also susceptible to stress deformation so that the change in resistance value due to the stress deformation ^ is as large as possible in order to improve force detection accuracy. .

In addition, as an alternative to the strain gauge 80, a piezo electric resistance element that detects a change in the pile due to the pressure applied to the disc spring 76, or a position sensor that detects the displacement of the plate panel 76, etc. There is.

Next, the operation of the third embodiment will be described.

When the rider applies pedaling force to the pedals 8R and 8L to rotate the drive shaft 4 in the R direction, this rotational force is transmitted to the sprocket 2c via the drive side portion of the one-way clutch 72. . At this time, the driven side portion of the one-way clutch 72 attempts to displace by a displacement amount corresponding to the stepping torque along the axial direction toward the sprocket side. The force to push more inward acts. This pushing force is applied to the disc spring 76 holding the sprocket 2 c via the bearing 74, and causes stress distortion in the disc spring 76. This stress-strain is This reflects the axial movement amount of the sprocket 2c by the switch 72, that is, the magnitude of the stepping torque.

The resistance value of the strain gauge 80 changes due to the stress strain of the flat panel 76. This changed resistance value is detected by the controller 14. The controller 14 previously stores in its internal memory a reference table indicating the correspondence between the resistance value of the strain gauge 80 and the stepping torque, and compares the detected resistance value of the strain gauge with the reference table. To obtain the stepping torque T. As in the second embodiment, the controller 14 controls the electric motor 37 so that the electric motor 37 is driven to rotate with the auxiliary torque Te calculated based on the input torque T based on S. It is transmitted to the chain 12 via the 3¾ sprocket 11.

As described above, in the embodiment of ^ 3, the effect of M and the effect of M in the case of ii in 31 can be received as well as-', and the plate by the pushing force of the one-way clutch 7 2 which is required even in general: 1 turn Since the torque is calculated based on the stress strain of the spring 76, the space and ffifil of the torque detecting mechanism can be significantly reduced and the apparatus can be simplified.

Further, in the embodiment of 333, the one-way clutch 72 is housed inside the cylindrical housing portion 82 of the sprocket 2c, and indirectly from the outside of the housing J, ';:! The structure in which the person is placed within the same width that the 7 and 6 hold, so the stroke in the direction of the arrow can be shorter. The advantage is that i is advanced to i by the sampling of the means of detecting the corresponding to the ingress torque by means of the gauge 80, which is thinly formed in the face liif of the disc spring 76. Thus, the embodiment of FIG. 13 has an effect that is superior to the embodiment of FIG. 2 in terms of the space.

The embodiments of the present invention have been described above. However, the present invention is not limited to the above examples, and can be arbitrarily and suitably changed within the scope of the present invention.

For example, in each of the above embodiments, an electric motor was used as an example of a means for providing auxiliary torque, but the present invention is not limited to this, and any other power means, such as a gasoline engine, may be used. It is.

Also, in FIG. 3 (b) of the first embodiment, two out of the teeth 11a of the driving sprocket are shown. One is the force fitting into the link opening 12b. Of course, the number may be one or three or more.

In the second embodiment, the position of the ratchet teeth in the axial direction is detected by the position sensor. However, a piezoelectric sensor that detects a change in the extrusion pressure due to the axial displacement of the ratchet teeth may be used. It is also possible to attach a strain gauge to the ratchet piece and calculate the stepping torque based on the amount of stress distortion of the ratchet piece. Further, in the third embodiment, the shape of the dish panel 76 can be arbitrarily changed, and holding means other than the bearing 74 can be used.

Claims

The scope of the claims

1. Main sprocket with chain installed, detecting means for detecting depression torque due to pedal depression force, driving means capable of outputting auxiliary torque for assisting pedal depression force, and detected depression torque A power assisted bicycle having a control means for controlling the driving means based on

The drive sprocket further includes a drive sprocket connected to a torque output shaft of the drive means, wherein the drive sprocket is provided at a chain portion where the main sprocket is fitted to the fifi chain, together with the main sprocket. The power assist system is characterized by being arranged so as to be fitted from above.

2. The power assist drive i according to claim 1, wherein the driving sprocket is disposed in a direction of the main sprocket in a direction.

3. The opening of the chain has a width of the intercept, and the plate of the main sprocket is designed so that both the teeth of the main sprocket and the teeth of the driving sprocket can enter the opening together. 3. The power assisted rotation according to claim 1 or 2, wherein the power assisted rotation is formed to be thinner.

4. The teeth of the main sprocket and the teeth of the | ¾¾ driving sprocket, which have entered the opening of the chain, are formed so as to be symmetrically arranged in the opening. One of the claims 1 to 3 requires a 勋 cast bicycle.

5. The power assisted bicycle according to any one of claims 1 to 4, wherein the teeth of the driving sprocket are formed at a pitch that is substantially the same as the pitch of the teeth of the main sprocket. .

6. The power assist according to claim 1, wherein a rotation axis of the driving sprocket is substantially parallel to a rotation axis of the main sprocket.

7. The drive sprocket according to any one of claims 2 to 6, wherein a diameter of the drive sprocket is smaller than a half of a diameter of the main sprocket so as not to contact a drive shaft of the main sprocket. Or power assisted turning according to item 1.

8. The main sprocket includes a central shaft portion and an outer peripheral portion having a plurality of teeth, The power assisted bicycle according to any one of claims 2 to 7, wherein the central shaft portion is formed so as to protrude outward in the direction with respect to the outer peripheral portion.

9. The power-assisted bicycle according to any one of claims 1 to 8, wherein the driving means includes an electric motor.

10. The method according to claim 1, wherein the driving unit includes a one-way clutch that transmits power from the driving side to the driven side and does not transmit power in the reverse direction. 10. Power assist bicycle.

11. One-way clutch means interposed between the drive shaft and the main sprocket for transmitting only rotation of the drive shaft in the vehicle body forward direction to the main sprocket,

The detecting means detects a distortion displacement amount based on a deformation of the -direction clutch means caused by the pedal depression force,

The power assisted rotation I according to any one of claims 1 to 10, wherein the control means controls the driving means based on the detected strain displacement S.

1 2. The one-way clutch stage is displaced in accordance with the pedal depression force, and the detection means sets the axial displacement of the one-way clutch means as a strain displacement ^. The power-assisted self-rotation according to claim 11, wherein the power assisted rotation is detected.

13. The method of claim 11, wherein the one-way clutch means is a ratchet gear.

2. Power assist rotation described in 2.

14. The power assisted vehicle according to any one of claims 11 to 13, wherein the detection means is a position sensor fixed to a vehicle body frame.

15. An elastic holding means for holding the main sprocket is further provided, and the detecting means detects a distortion displacement amount of the holding means distorted or displaced by deformation of the one-way clutch means. The power-assisted bicycle according to claim 11, which is detected.

16. The one-way clutch means according to claim 15, wherein the one-way clutch means is displaced so as to exert a stress on the holding means in an axial direction of the drive shaft when the drive shaft rotates by the pedal depression force. Power assisted bicycle.

17. The power-assisted turning vehicle according to claim 15 or claim 16, wherein the detecting means is a strain gauge attached to a surface of the holding means and detecting a stress strain thereof.

18. The power assisted bicycle according to any one of claims 1 to 17, wherein the power assisted bicycle has substantially the same frame structure as a general bicycle.

1 9. A drive that can be attached to a bicycle that transmits pedaling force to the driving wheels via a main sprocket and a chain installed on the main sprocket, and that can output an auxiliary torque to assist the front pedaling force. A device,

A drive sprocket is connected to a torque output shaft of the drive device,

When the drive sprocket is mounted on the front wheel, the drive sprocket fits into the chain where the main sprocket fits into the chain together with the main sprocket from inside the chain. A drive device characterized by being formed so as to be compatible with each other.

20. The driving sprocket is disposed inside the main sprocket in the 'ι': ιΐι direction, when the driving device is mounted in the rotation, ^ rrni.

The drive unit noted in 1-9.

2 1. The open part of the chain has a width of the width, the plate j¾i of the sprocket is formed thinner than usual, and the front drive sprocket has the front: the sprocket teeth and the drive sprocket teeth. The drive device according to claim 19 or claim 20, characterized in that the drive device is formed so as to be inserted into the opening together.

22. The drive sprocket is formed such that the teeth of the drive sprocket and the teeth of the main sprocket, which have entered the opening of the chain together, are arranged symmetrically within the opening. The drive device according to any one of claims 19 to 21, wherein:

23. The driving device according to any one of claims 19 to 22, wherein the teeth of the driving sprocket are formed at substantially the same pitch as the teeth of the main sprocket. .

24. The rotating shaft of the driving sprocket is formed so as to be substantially parallel to the rotating shaft of the main sprocket when the driving device is mounted on the bicycle. The drive device according to any one of claims 19 to 23.

25. The drive sprocket has a diameter smaller than half the diameter of the main sprocket so that the drive sprocket does not contact the drive shaft of the main sprocket when mounted on the bicycle. The drive device according to any one of claims 20 to 24, wherein:

26. The main sprocket includes a central shaft portion and an outer peripheral portion having a plurality of teeth, and the central sprocket portion is formed so as to project axially outward with respect to the outer peripheral portion. 52. When the device is mounted on the bicycle, the drive sprocket is arranged in proximity to the axially inner wall of the portion protruding outward in the axial direction of the central part of the bicycle. A power assisted bicycle according to any one of Items 2 to 5.

27. The drive device according to any one of claims 19 to 26, wherein the auxiliary torque is provided by an electric motor.

28. Transmitting power from the driving side to the driven side, and not transmitting power in the opposite direction, while additionally including a clutch, as described in any one of the charging requests 19 to 27. Drive.

2 9. A driving sprocket which is formed so as to be connectable to a torque output shaft of a driving hand & mounted on a bicycle,

The turning vehicle transmits a pedal depression force to driving wheels via a main sprocket and a chain installed in the main sprocket, and the driving means can output an auxiliary torque for assisting the pedal depression force,

The drive sprocket, when connected to the torque output shaft of the drive means, is capable of fitting together with the main sprocket from inside the chain to the chain portion where the main sprocket is fitted to the chain. A driving sprocket characterized by being formed.

30. The driving sprocket according to claim 29, wherein the teeth of the driving sprocket are formed at substantially the same pitch as the teeth of the main sprocket.

31. The driving sprocket is formed to have a diameter smaller than one half of a diameter of the main sprocket so as not to contact a driving shaft of the main sprocket. 30. Drive sprocket according to 30.

32. The teeth of the drive sprocket are formed so as to be arranged symmetrically with respect to the teeth of the main sprocket which have entered the opening of the chain together. Item 31. A drive sprocket according to any one of items 1 to 13.

33. The drive sprocket according to claim 32, wherein an opening of the chain has a normal width, and a plate thickness of the main sprocket is formed smaller than usual.

34. The three-wheeled bicycle according to any one of claims 1 to 18, wherein the driving means is formed as a single unit formed by a housing.

35. The driving device according to any one of claims 19 to 28, wherein the driving device is formed as a single unit covered by a housing.