JP2002104272A - Power assisted bicycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power assisted bicycle capable of reconciling reducing weight and securing strength with enhancing appearance. SOLUTION: This power assisted bicycle 1 to add assist power in response to pedal stepping force acting on a drive shaft includes a first frame 3a extending backward from a handle shaft frame 16, a second frame 3b extending backward from the handle shaft frame while being lined up below the first frame, a third frame 3c to link the first frame to the second frame, and a cover housing 8 to cover a closed area 15 demarcated by the first, second and third frames. A driving unit 13 and a battery 20 are stored in the cover housing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power-assisted bicycle for adding auxiliary power to pedal effort and a conventional bicycle.

[0002]

2. Description of the Related Art Conventionally, there has been proposed and implemented an electric assist bicycle that detects a stepping torque applied from a pedal, applies an electric assist torque to a rotating mechanism based on the detected stepping torque, and assists human power of a passenger. Have been.

In such an electric assist bicycle, a torque detecting mechanism, an electric motor, and the like are added to a vehicle body frame, and are protected by, for example, covering them with a cover or the like.

[0004]

However, in the conventional electric assist bicycle, since a torque detecting mechanism, an electric motor, and the like are newly added to the body frame, there is a problem that the weight increases and the smart appearance is lacking. is there.
If an attempt is made to reduce the weight of the body frame to solve this problem, the strength will be insufficient.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and has as its object to provide a power-assisted bicycle that achieves both reduction in weight, securing of strength, and improvement in appearance, and an ordinary bicycle.

[0006]

In order to solve the above-mentioned problems, a power assisted bicycle for applying auxiliary power in accordance with a pedaling force acting on a drive shaft, comprising: a first frame extending rearward from a handle shaft frame; A second frame aligned with a lower side of the first frame and extending rearward from the handle shaft frame; a third frame connecting between the first frame and the second frame; And a cover housing that covers the closed area defined by the third frame.

According to the present invention, since the front closed area where the frame structure of the vehicle body is easily twisted is surrounded by the cover housing, the frame structure can be prevented from being twisted. In other words, it is possible to reduce the weight of the frame as much as possible while maintaining the strength of the frame structure, and thus reduce the weight of the entire electrically assisted bicycle. That is,
The cover housing of the present invention has a function of improving the strength of the vehicle body frame, unlike a mere cover that covers an electric motor, a detection mechanism, and the like of the related art.

[0008] Preferably, an extension of a saddle frame (seat tube) for supporting the saddle intersects the closed area. For example, the extension is connected to an arbitrary position inside the closed region. By intersecting the saddle frame, which requires the weight of the occupant, in the closed area, torsional stress is concentrated in the closed area, and this is completely prevented by the cover housing, thereby torsionally deforming the entire body frame. Can be accurately prevented.

Preferably, the drive unit for providing the auxiliary power and / or the power supply for the drive unit is housed inside the cover housing. Thus, the cover housing can secure the strength of the vehicle body, protect the drive unit and the battery, and improve the appearance by hiding them.

This drive unit can also help to improve the strength of the body frame. Preferably, a side surface of the drive unit projects from the cover housing to support the cover housing. Thereby, bending of the cover housing due to torsion can be prevented, and the strength of the vehicle body frame can be further improved. This drive unit is preferably attached to the third frame in order to realize a resultant force mechanism. Further, it is preferable that the lower end of the saddle frame for supporting the saddle is connected to the drive unit so that the frame can bear a load such as the weight of the occupant.

[0011] The first frame may be extended to near the rear wheel hub. Thereby, the structure of the vehicle body frame can be simplified. The rear end of the second frame is preferably connected to a support for the drive shaft. Further, the lower end of the third frame may be connected to the support of the drive shaft, and the upper end may be connected to the first frame.

The cover housing can be used for other purposes. For example, the cover housing can be used to protect the main sprocket by at least partially covering the main sprocket for transmitting the pedaling force to the rear wheel. By providing a storage pocket at the top of the cover housing, the convenience of the electric assist bicycle can be improved.

[0013] Preferably, the cover housing is made of a lightweight, high strength plastic material. For the purpose of improving the appearance or hobby, as the plastic material, a colorless or colored transparent material, or an opaque material having at least one of a color and a pattern can be used. The cover housing is configured, for example, by attaching reinforcing plates from both left and right sides of the closed area.

In order to realize the resultant mechanism of the present invention, the present invention preferably further comprises a main sprocket having a chain mounted thereon, and a drive sprocket connected to a torque output shaft of the drive unit. Is arranged so as to fit together with the main sprocket from the inside of the chain to the chain portion where the main sprocket fits into the chain.

Here, "fit from the inside of the chain" means
Refers to fitting outward from the inner region surrounded by the chain. According to the present invention, when the drive unit is controlled based on the stepping torque to output the auxiliary torque, the drive sprocket connected to the torque output shaft of the drive unit rotates. At this time, since the main sprocket and the driving sprocket are fitted to the chain, the main sprocket provides the pedaling force to the chain and the driving sprocket provides the rotational force to the chain. As a result, the resultant force of the depression torque and the auxiliary torque is achieved. According to this aspect, since the resultant force is realized by a simple mechanism of fitting the drive sprocket to the chain together with the main sprocket, the mechanism can be made lighter and more compact. In addition, since the drive sprocket fits into the chain where the main sprocket fits into the chain, the drive sprocket appears to overlap with the main sprocket, thus making the bicycle more compact than the conventional chain direct drive system. There is no fear of damaging the appearance. Most preferably, the drive sprocket is located axially inward of the main sprocket. As a result, when viewed from outside the bicycle,
The drive sprocket is hidden by the main sprocket. Also,
It is also preferable from a mechanical point of view.

In order to realize a torque detecting mechanism which is very suitable for the present invention, one aspect of the present invention is to form a drive shaft and a main sprocket such that substantially only one rotation of the drive shaft is transmitted to the main sprocket. One-way clutch means to be coupled, detection means for detecting a physical quantity that changes by deformation according to the pedaling force of the one-way clutch means, and control means for controlling auxiliary power based on at least the physical quantity detected by the detection means, Is further comprised.

According to the present invention, when the drive shaft rotates in one direction (corresponding to the forward direction of the bicycle) by applying the pedal depression force, the depression torque is transmitted to the sprocket via the one-way clutch means. On this sprocket, for example, the tensile force from the chain acts as a load,
Due to the stress caused by the antagonism of this load and the stepping torque,
The one-way clutch means is distorted and / or deformed such that its components are displaced along the direction of deformation. This deformation is determined according to the pedaling force. That is, the degree of deformation increases as the pedaling force increases, and conversely, the degree of deformation decreases as the pedaling force decreases. Thus, the above-mentioned antagonistic stress causing deformation and the force opposing it are balanced.
As a force opposing the antagonistic stress, it is preferable that an elastic force is applied to the one-way clutch means so as to restore its deformation. For example, an elastic body for exerting an elastic force against deformation of the one-way clutch means is provided. The components of the one-way clutch means may be responsible for at least a part of this elastic force.

The deformation of the one-way clutch means includes not only the case where all or a part of the one-way clutch means is elastically deformed, but also the relative position between the rigid components of the one-way clutch means. (Including rotation). In order to generate the deformation according to the pedaling force most efficiently, it is preferable that the one-way clutch means be deformed so as to expand and contract along the axial direction of the drive shaft to a length corresponding to the pedaling force.

The detecting means detects a physical quantity which changes by the deformation of the one-way clutch means according to the pedaling force. This physical quantity includes not only the components of the one-way clutch means but also the physical quantities of other members associated with the one-way clutch means. For example, the position or stress distortion of at least one part constituting the one-way clutch means with respect to the body frame, the relative positional relationship between at least two parts constituting the one-way clutch means (clearance, angle between parts, etc.) A change in pressure against the deformation direction of the one-way clutch means, and a stress distortion of a member (for example, an elastic body) arranged against the deformation direction of the one-way clutch means. Since the change in the physical quantity is determined according to the pedal effort, the control means can estimate the pedal effort based on the detected physical quantity, and thus can control the auxiliary power.

As described above, according to this aspect, the auxiliary power is controlled based on a physical quantity that is changed by deformation of the one-way clutch means, which is indispensable to the bicycle, in accordance with the pedaling force. This eliminates the need to add a separate component such as a large coil spring or disk for torque detection, which is not used in a bicycle, and can achieve the above-described object of the present invention at a higher level.

In this embodiment, the elastic member preferably arranged to oppose the deformation of the one-way clutch means does not directly receive the opposing stress but receives the force in the direction of the deformation via the one-way clutch means. It doesn't have to be a body. In addition, since it is possible to reduce the amount of deformation of the one-way clutch means, it is possible to arrange a substantially flat elastic body having a height smaller than the width in the direction of deformation of the one-way clutch means. it can. As a result, a large space can be saved. Such a substantially flat elastic body includes, for example, a disc spring.

As a specific embodiment of such a one-way clutch means, there is a ratchet gear described later, and a torque detecting mechanism is used for the ratchet gear. The above configuration can also be applied to a normal bicycle having no power supply or drive unit.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a power assisted bicycle according to each embodiment of the present invention will be described with reference to the drawings.
The power assisted bicycle described below will be described as an electric assisted bicycle that applies an auxiliary torque by an electric motor as an example. (First Embodiment) FIG. 1 shows a schematic frame structure of an electric assist bicycle 1 according to a first embodiment of the present invention. Each frame is made as thin as possible to reduce weight (eg, less than 20 kg for the entire bicycle), for example, from metal or reinforced plastic pipes or reinforced paper tubes, or from metal or reinforced plastic plates. Be composed.

The frame structure of the electrically assisted bicycle 1 includes a front upper frame 3a and a front lower frame 3b arranged below and substantially vertically aligned with the frame.
Contains.

The front end of the front upper frame 3a is connected to the handle shaft frame 16, and the rear end is connected to the rear frame 3e. The rear frame 3e extends near the hub of the rear wheel. The front upper frame 3a and the rear frame 3e can be formed as a continuous frame. Further, a saddle frame (seat tube) 3d is connected to the front upper frame 3a so as to intersect, and a saddle 1 is provided on the top of the saddle frame 3d.
8 is attached, and its lower end is supported by a drive unit 13 described later. Preferably, the height of the saddle frame 3d can be adjusted according to the height of the occupant.

The front end of the front lower frame 3b is connected to the handle shaft frame 16, and the rear end is connected to the pedal bearing 17. This pedal bearing 17 has
A drive shaft 4 is rotatably supported, and pedals (not shown) are respectively attached to left and right ends of the drive shaft via crank rods (not shown). Further, an intermediate support frame 3c extends from the pedal bearing 17 and is connected to the rear frame 3e. The intermediate support frame 3c and the saddle frame 3d may be formed as a continuous frame.

A first feature of the illustrated frame structure is that the front upper frame 3a, the front lower frame 3b and the intermediate support frame 3c define a closed area 15 surrounded by them. Members required for the electric assist bicycle can be arbitrarily and suitably arranged inside the closed area 15. For example, the drive unit 13 is attached to the intermediate support frame 3c. This drive unit 13
The electric assist torque is provided based on the detected stepping torque, which will be described in detail in a second embodiment. Further, the drive unit 1 is provided on the front upper frame 3a.
3 is provided with a battery 20 for supplying power. The arrangement of these members can be arbitrarily changed.

A second feature of the illustrated frame structure is that the longitudinal range of the closed area 15 extends from the handle shaft frame 16 to the position of the saddle frame 3d or a position behind the saddle frame. is there. This range is where torsional stress is relatively likely to act on the body frame due to the weight and / or inertia of the occupant and the force applied to the steering wheel. In particular, in the present embodiment, since each frame is made thin to reduce the weight, the frame structure is likely to be twisted as it is.

In order to solve this problem, reinforcing plates 7R and 7L each having a shape corresponding to the side surface shape of the closed area are attached to both left and right sides of the closed area 15, as shown in FIG. As a material for these reinforcing plates 7R and 7L, for example, a lightweight metal such as aluminum or duralumin can be used. More preferably, a high-strength and lightweight synthetic resin, that is, a plastic material is used. For example, engineering plastics (polyamide, polyacetal,
Polycarbonate, polybutylene terephthalate, modified polyphenylene ether, ultra-high molecular weight polyethylene, etc.), super-engineering plastics with further enhanced strength, fiber-reinforced plastics (FRP, GFR)
P, CFRP), carbon fiber, and the like.

The reinforcing plate 7R, 7L has a closed area 15
25R, 25L for covering the latter half of the upper surface
And bent portions 26R and 26L for covering the back surface, and bent portions 27R and 27L for covering the bottom surface. The reinforcing plates 7R and 7L have convex side surfaces 21R (FIG. 1) on both left and right sides of the drive unit 13 respectively.
Circular openings 22R and 22 through which (FIG. 2) can pass and protrude.
L is formed. Further, the reinforcing plates 7R and 7L have holes 28R and 28L and holes 29R and 29L through which the handle shaft frame 16 and the saddle frame 3d can pass, respectively.
Are formed.

As shown in FIG. 2, the front upper frame 3a and the rear frame 3e, which is an extension thereof, are composed of two plates 6R and 6L, and a reinforcing plate can be easily attached. Installation of the reinforcement plate
For example, it can be performed using welding, an adhesive, or bolts and nuts (not shown).

The plates 6R and 6L are preferably changed from a flat state to a slightly twisted state in order to improve the bending strength against a force from the side. Further, the front upper frame 3a may be formed of a normal pipe instead of a plate. Conversely, other frames may be made up of plates instead of pipes, as appropriate.

FIG. 3 is a perspective view of the electric assist bicycle 1 on which the reinforcing plates 7R and 7L are mounted. The reinforcing plate mounted on each frame defines a cover housing 8 surrounding the closed area 15. Here, the drive shaft 4
As a one-way clutch means for transmitting only one-way rotation to the sprocket, a main sprocket 2 as a driven side is coaxially mounted via a ratchet gear described later. In the example shown, the main sprocket 2 is outside the cover housing 8 or closed area 15.

As described above, in the first embodiment, the front closed region 15 where the frame structure is easily twisted is surrounded by the cover housing 8 made of a lightweight and high-strength material. Deformation can be prevented. In other words, it is possible to reduce the weight of the frame as much as possible while maintaining the strength of the frame structure, and thus reduce the weight of the entire electrically assisted bicycle. If the drive unit 13 is formed of a high-strength housing, the drive unit itself can be used as a frame support for reinforcement. The left and right convex side surfaces 21R (FIG. 1) and 21L (FIG. 2) of the drive unit 13
Since the projections pass through the circular openings 22R and 22L of R and 7L, the entire reinforcing plate can be prevented from bending and the reinforcing strength of the cover housing 8 can be further improved. The reinforcing plate may be connected to the drive unit 13.

Further, the cover housing 8 accommodates the drive unit 13 and the battery 20 necessary for the electric assist bicycle, so that they can be protected and the appearance of the bicycle can be improved. Of these, the convex side surfaces 21R (FIG. 1) and 21L (FIG. 2) on both the left and right sides of the drive unit 13 can be seen from the outside. Can be. Further, by coloring the reinforcing plates 7R and 7L in a color that suits the passenger's taste, making them transparent, or applying a colorless or colored design pattern, the overall design of the electric assist bicycle is further improved. Can be done.

As described above, according to the embodiment of the present invention, by providing only one cover housing 8, it is possible to simultaneously achieve weight reduction, securing of strength and improvement of appearance. The reinforcing plates 7R and 7L can be arbitrarily and suitably changed, and other modified examples are shown in FIGS. 4 (a) and 4 (b).

In FIG. 4A, the cover housing 8a partially covers the main sprocket 2. This allows
The cover housing 8a can also be used as a cover for the main sprocket 2.

In FIG. 4B, a pocket 9 is provided at the upper part of the cover housing 8b to enhance the convenience of the electric assist bicycle. (Second Embodiment) The second embodiment relates to a resultant mechanism for assist torque and stepping torque in the electric assist bicycle 1. This resultant force mechanism is applied to the electric assist bicycle 1 according to the first embodiment. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description is omitted.

FIG. 5 is an enlarged front view of the vicinity of the main sprocket 2 as viewed from the rear side in the axial direction. An endlessly rotating chain 12 is stretched between the main sprocket 2 and a free wheel (not shown) provided inside the rear wheel power mechanism 10 (FIG. 1). As is well known, the pedaling force in the forward direction rotates the drive shaft 4, and this rotating force rotates the main sprocket 2 as a stepping torque, and the stepping torque is transmitted via the chain 12 to the rear wheel power mechanism 10.
As a result, the rear wheel is rotated so that the bicycle 1 runs forward.

The drive sprocket 11 is arranged in the chain portion where the main sprocket 2 fits into the chain 12 so as to fit together with the main sprocket 2 from the inside of the chain (the region surrounded by the chain). . 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 drive sprocket 11 is formed to be about 38 mm.

When viewed from the outside of the bicycle, the driving sprocket 11 is entirely hidden inside the main sprocket 2 in the axial direction, and is only partially visible from the hole of the main sprocket 2. Therefore, there is no risk of damaging the appearance of the bicycle.

In order to show the fitted state of the drive sprocket 11 and the main sprocket 2 to the chain 12, a part of a partially cutaway side view of the fitted state taken along line XX 'of FIG. As shown in FIG. As shown in the figure, a chain link (roller link or pin link) 12a
One tooth 2a of the main sprocket 2 and one tooth 11a of the driving sprocket 11 are fitted together in one opening 12b of the first sprocket. In order to always maintain this fitted state, the interval (pitch) between the adjacent teeth 11a of the driving sprocket 11 and the pitch of the teeth 2a of the main sprocket 2 are formed substantially the same. Preferably, the link opening 12
The main sprocket 2 and the driving sprocket 11 may be formed such that the teeth 2a and the teeth 11a are substantially symmetric with respect to the virtual line 12c passing substantially in the center of b.

Since the central shaft portion 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 example shown, two stages are provided), the driving sprocket 11 is used as the main sprocket 11. 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 so as to protrude outward in the axial direction by about 9.4 mm with respect to the outer peripheral portion.

FIG. 6 shows a state in which the drive sprocket 11 is operatively connected to the drive unit 13 via a drive shaft 35a extending parallel to the drive shaft 4, in addition to the above-mentioned fitted state. The drive unit 13 is based on an electric motor 37 supplied with power from the battery 20, a speed reduction mechanism 35 for reducing the rotation of the motor and transmitting the rotation to the drive shaft 35a of the drive sprocket 11, and a distortion stress detection signal described later. A control unit (controller) 1 that calculates the stepping torque applied to the pedal and controls the rotation speed of the motor 37 based on the calculation result.
4 in the housing. A so-called one-way clutch (not shown) for transmitting power only in one direction is provided in the transmission path of the auxiliary torque in the speed reduction mechanism 35. The one-way clutch is configured and connected so as to transmit the auxiliary torque from the electric motor 37 to the driving sprocket 11 but not transmit the torque in the opposite direction, that is, transmitting the torque from the driving sprocket to the speed reduction mechanism 35. As a result, the load of the electric motor 37 when it is not driven is
Light driving is always possible without transmission to the vehicle.

When an auxiliary torque is provided to the drive sprocket 11 by the drive unit 13, the teeth 11
a is sequentially fitted into the link opening 12b of the chain 12 together with the teeth 2a of the main sprocket 2, whereby the resultant force of the auxiliary torque and the stepping torque is achieved.

As described above, in the second embodiment, since the resultant force mechanism is formed by the drive sprocket 11 fitted to the chain 12 together with the main sprocket 2, a simple drive mechanism is provided as a separate single drive unit 13 Can be easily attached to the bicycle. Thereby, the weight reduction and cost reduction of the electric assist bicycle 1 can be achieved in addition to the effects of the first embodiment. Preferably, the width of the link opening 12b of the chain 12 (FIG. 6) is formed to the same size as that of a normal bicycle, and instead, the thickness of the main sprocket 2 is reduced while maintaining strength (for example, 1.6 mm). Degree) is good. At this time, it is preferable that the thickness of the tooth portion of the driving sprocket 11 is formed to be substantially the same as the plate thickness of the main sprocket 2. Thereby, the main sprocket 2 and the driving sprocket 11, and thus the electric assist bicycle 1 can be further reduced in weight. (Third Embodiment) In a third embodiment, a torque detection mechanism of the electric assist bicycle 1 will be described with reference to FIGS. This torque detection mechanism is applied to the electric assist bicycle 1 according to the first and second embodiments. The first
The same components as those of the second embodiment are denoted by the same reference numerals, and detailed description is omitted.

FIG. 7 shows a ratchet gear provided with a torque detecting mechanism according to the third embodiment. The main sprocket 2 is connected to the drive shaft 4 via the ratchet gear.
By this, only the forward stepping torque received from the drive shaft 4 is transmitted to the main sprocket 2.

As shown in FIG. 8, the ratchet gear includes a bridge 100 and teeth 112. In the piece section 100, 3
Two ratchet pieces 102 are arranged on the second engagement surface 110 at equal angles along the circumferential direction. The ratchet piece 102 is made of a rigid body, and is rotatable about an axis near the second engagement surface 110 and substantially along the radial direction of the engagement surface. When no force acts on the ratchet piece 102, the ratchet piece 102
9 is urged by the piece rising spring 104 so as to form a predetermined angle with respect to the engaging surface 110 (equilibrium direction 160 in FIG. 9). As shown in FIG. 9, the ratchet piece 1
When 02 deviates from the equilibrium direction 106 in the ascending direction a or the descending direction b, the piece rising spring 104 exerts a slight elastic force on the ratchet piece 102 so as to return the deviation to the equilibrium direction 106.

A piece bore 106 for receiving the drive shaft 4 is formed at the center of the piece 100. The piece bore 106 also penetrates a cylindrical portion 103 protruding from the back surface 101 of the piece 100. are doing. On the back surface 101, a circular groove 155 (FIG. 7) is formed around the outer periphery of the cylindrical portion 103, and a number of steel balls 152 are rotatably fitted in the circular groove 155. As a result, a bearing for a load bearing and a sliding bearing in the axial direction is formed on the back surface 101.

A disc spring 124 is brought into contact with the back surface 101 of the bridge portion 100 through the central portion 127 through the cylindrical portion 103. At this time, the disc spring 124 slidably contacts the back surface 101 via the steel ball 152, that is, the load receiving bearing, in a direction that elastically opposes the pressure from the bridge portion 100. Disc spring 1
Strain gauges 126 are installed at two locations facing each other on the surface of 24 at a 180-degree positional relationship. These strain gauges 126 are electrically connected to the control unit 14 via the lead wires 128. More preferably, three or more strain gauges may be installed on the disc spring 124. At this time, it is preferable that the plurality of strain gauges are installed so that each of the strain gauges has a rotationally symmetric position on the surface of the disc spring 124.

The disc spring 124 is housed in the inner bottom 132 of the bowl-shaped support 130. The support 130 has a support bore 133 penetrating the center to receive the drive shaft 4.
And a support cylindrical portion 134 protruding from the rear surface.
Bearings 138 for both axial and radial loads are engaged with the inner wall of the support cylindrical portion 134 (see FIG. 7). The bearing 138 is locked by a stopper slope 144 formed on the drive shaft 4.

On the inner wall of the piece bore 106, first anti-rotation grooves 108 extending in the axial direction 5 are formed at four places. In the outer wall portion of the drive shaft 4 which is in sliding contact with the inner wall of the piece bore 106, second anti-rotation grooves 140 extending in the axial direction 5 are formed at four locations so as to face the first anti-rotation grooves 108. ing. As shown in FIG. 10A, the first anti-rotation groove 108 and the second anti-rotation groove 140 facing the same form a cylindrical groove extending along the axial direction.
A number of steel balls 150 are accommodated in each of the cylindrical grooves so as to fill them. As a result, the bridge portion 100 can move in the axial direction 5 with the minimum frictional resistance, and the relative rotation with respect to the drive shaft 4 is prevented. This is a kind of ball spline, but other types of ball splines, such as endlessly rotating ball splines, can be applied as such slidable rotation preventing means.

It is also possible to use means other than the ball spline. For example, as shown in FIG. 10B, a projection 140a extending in the axial direction is provided on the drive shaft 4, and the third rotation preventing groove 1 for accommodating the projection 140a is provided.
A so-called key spline type in which 08a is formed in the piece portion 100 is also applicable as the rotation preventing means. In FIG. 10B, the protrusion 140a may be provided on the piece 100 side, and the third rotation preventing groove 108a may be provided on the drive shaft 4 side. Further, as shown in FIG. 10 (c), a fourth anti-rotation groove 108b extending in the axial direction and a fifth anti-rotation groove 140b facing the fourth anti-rotation groove 108b are provided on the bridge portion 100 and the drive shaft 4, respectively. A so-called key groove type in which a key plate is accommodated in a rectangular parallelepiped groove formed by the groove of the above-mentioned type is also applicable as the rotation preventing means.

A plurality of ratchet teeth 114 for engaging with the ratchet piece 102 are formed on the first engaging surface 121 of the tooth portion 112. Ratchet teeth 114 are formed alternately and periodically along a circumferential direction of the tooth portion.
And a gentler inclined surface 116 with respect to the engaging surface 121 of FIG.

The tooth portion 112 is supported by the drive shaft 4 so that the first engagement surface 121 faces the second engagement surface 110 of the bridge portion 100. The ratchet bridge 102 and the ratchet teeth 112 are connected to each other. Engaged (FIG. 9). At this time, the drive shaft 4 passes through the tooth bore 120 formed at the center of the tooth 112 via the collar 111, and is fixed from the end 142 via the washer 122 (FIG. 7). Further, the tooth portion 112 is connected to a support 130 that is rotatable with respect to the main sprocket 2 and the drive shaft 4. Thus, a ratchet gear that connects the drive shaft 4 and the main sprocket 2 so that only the rotation of the drive shaft 4 in the vehicle body forward direction is transmitted to the main sprocket 2 is completed.

Preferably, the offset spring 136 is
It is preferable to be interposed between the stopper slope 144 of the drive shaft 4 and the back surface 101 of the bridge portion 100. When the pedaling force is equal to or less than a predetermined value (for example, when the pedaling force is practically close to zero), the offset spring 136 generates a piece so as to generate a clearance between the steel ball 152 housed on the back surface 101 and the disc spring 124. 100 is displaced axially.

Next, the operation of the third embodiment will be described. When the rider applies a pedal depression force to a pedal (not shown) to rotate the drive shaft 4 in the forward direction of the vehicle body, the rotation force is transmitted to the bridge 100 that is non-rotatably supported with respect to the drive shaft 4. At this time, as shown in FIG. 9, the ratchet piece 102
Given d, its tip abuts the steeper slope 118 of the ratchet teeth of tooth 112 and attempts to transmit this force to the ratchet teeth. Since the ratchet teeth 112 are connected to the main sprocket 2, the ratchet pieces 1
02 receives a force Fp due to a driving load from a steeper slope 118. Ratchet piece 102 given opposing forces Fp and Fd from both ends.
Rotates in the direction a and stands up. The piece 100 moves inward in the axial direction due to the rise of the ratchet piece 102, and pushes the disc spring 124 interposed between the piece 100 and the support 130. The disc spring 124 applies an elastic force Fr to the bridge 100 in opposition thereto. This force Fr and the force reflecting the pedal depression force for moving the piece portion 100 in the axial direction are balanced in a short time. Thus, the stress-strain of the disc spring 124, the clearance between the bridge portion 100 and the tooth portion 112, the angle of the ratchet bridge 102 with respect to the second engagement surface 110,
Position of the piece part 100 with respect to the body frame and the disc spring 12
The pressure at which 4 is pushed is a physical quantity reflecting the pedaling force. Therefore, it is possible to estimate the stepping torque T by detecting at least one of them.

In the present embodiment, as an example, the disc spring 124 is used.
The stress strain of is detected. The control unit 14
At least the signals from the two strain gauges 126 provided on the disc spring 124 are subjected to an addition operation (including an average operation).
By averaging and measuring the stress-strain amounts at a plurality of places in this way, a large output change can be obtained even with the same stepping torque, and the noise component can be smoothed.
The S / N ratio can be improved, and the torque estimation accuracy can be further improved. This effect increases as the number of strain gauges increases.

Next, the control unit 14 calculates an assist assist torque Te to be applied based on at least the stepping torque T calculated as described above.
A control signal for instructing the electric motor 37 to rotate and drive with the auxiliary torque is calculated and output. Note that a vehicle speed sensor may be attached to the bicycle, and the assist torque Te may be calculated based on both the stepping torque T and the vehicle speed.

For example, in the simplest electric assist control, when the calculated stepping torque T becomes equal to or more than a predetermined value, the electric motor 37 is turned on to generate an auxiliary torque that maintains a predetermined ratio with respect to the stepping torque. It outputs a motor control signal for commanding, and otherwise outputs a motor control signal for turning off the electric motor. In this case, the electric motor 37 may be turned on only when the physical quantity (strain resistance value of the strain gauge) itself that reflects the pedaling force itself becomes equal to or more than a certain value.

When the pedal depression force is equal to or less than a predetermined value, the offset spring 136 is
Since the clearance is generated between the spring 01 and the disc spring 124, the steel ball 152 is less likely to collide with the disc spring 124 frequently. Thereby, the noise component of the strain gauge signal is reduced, and the stability of the torque detection and the electric assist control can be improved.

The third embodiment has the following more excellent effects. Since the ratchet gear and the torque detection mechanism are realized by one mechanism, the number of parts can be reduced, and the size, weight, and cost can be further improved. A disc spring that integrates a receiving load unit and a load detection sensor is used for the portion that detects the stepping torque.
Since one function is realized by one unit, in addition to the above effects, further reduction in size, weight, and cost can be achieved. As described above, the torque detection mechanism has been reduced in size, weight, and simplification at a higher level, so that the possibility of attaching the torque detection mechanism even to a normal bicycle has been further widened. For the reasons described in the above items and, the transmission loss of the load is reduced as compared with the conventional mechanism, and an assist feeling with good control responsiveness can be realized. For the reasons described above and above, the pedal has no unnecessary movement (until the sensor detects it) as compared with the conventional mechanism (using a coil spring), and the feeling when the pedal is depressed is less elastic than the conventional mechanism. In contrast, in the present embodiment, the feeling is the same as that of a normal bicycle.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described examples, and can be arbitrarily and suitably changed within the scope of the present invention. For example, in each of the above embodiments, the electric motor is used as an example of the means for providing the auxiliary torque, but the present invention is not limited to this, and any other power means, such as a gasoline engine, can be used. is there.

Further, the frame structure of the first embodiment, in particular, the frame in the cover housing 8 can be arbitrarily and suitably changed and added. For example, a frame for connecting the front upper frame 3a and the front lower frame 3b is newly provided,
The strength of the frame structure can be further increased. Also,
The shape of the closed region 15 is not limited to the example of FIG. 1 and can be arbitrarily changed as long as the vehicle body strength can be secured.

Note that the frame structure of the first embodiment is
The present invention can also be applied to a normal bicycle having no battery 20, drive unit 13, or the like. As a result, the effects of the present invention such as weight reduction, securing of strength, and improvement of appearance can be similarly enjoyed in a normal bicycle.

In the third embodiment, whether one of the ratchet gear pieces and teeth is attached to the sprocket and the other is attached to the drive shaft can be arbitrarily and suitably changed. For example, the bridge 100 is mounted on the sprocket side, the tooth 112 is slidably and non-rotatably mounted on the drive shaft 4, and the tooth 112
May be pushed. Further, in the third embodiment, the example in which the number of the ratchet pieces is three has been described, but it is needless to say that the number of the ratchet pieces may be two or four or more. FIG. 10 (a),
The number of grooves and the number of protrusions of the rotation preventing means shown in (b) and (c) may be other numbers than those described above. Further, the type and shape of the elastic body disposed against the deformation of the ratchet gear can be arbitrarily and suitably changed. For example, a rubber elastic body or the like can be used other than the disc spring and the coil spring.

[0067]

As described in detail above, according to the present invention, since the closed area of the front part of the vehicle body defined by the first, second and third frames is surrounded by the cover housing,
In the power-assisted bicycle, an excellent effect of achieving both reduction in weight, securing of strength, and improvement in appearance can be obtained.

Since the present invention is applied to a normal bicycle having no power supply or drive unit, the above effects can be similarly enjoyed in a normal bicycle.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic frame structure of an electric assist bicycle according to a first embodiment of the present invention.

FIG. 2 is a perspective view when a reinforcing plate is attached to the frame structure of FIG. 1;

FIG. 3 is a perspective view of the electric assist bicycle of FIG. 1 with a cover housing attached.

FIGS. 4A and 4B are diagrams showing a modified example of the cover housing in the electric assist bicycle according to the first embodiment of the present invention, wherein FIG. 4A is a cover housing that partially covers a sprocket, and FIG. 2 shows a cover housing with a pocket.

FIG. 5 is an enlarged front view of the vicinity of a sprocket for illustrating a resultant force mechanism of an electric assist bicycle according to a second embodiment of the present invention.

6 is a cross-sectional view of the resultant mechanism of FIG. 5 and an internal configuration diagram of a drive unit connected thereto.

FIG. 7 is a side sectional view of a torque detection mechanism according to a third embodiment of the present invention.

FIG. 8 is an exploded perspective view of a ratchet gear included in the torque detecting mechanism shown in FIG.

FIG. 9 is a diagram illustrating a fitting state of teeth and pieces of a ratchet gear for explaining the principle of the torque detection mechanism.

FIGS. 10A and 10B are diagrams showing examples of rotation preventing means for preventing relative rotation of a bridge portion with respect to a drive shaft, wherein FIG. 10A shows a ball spline, FIG. 10B shows a spline key, and FIG. FIG.

[Explanation of symbols]

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Michele Capuani Milan, Italy 20141, Via Pie Trasanta 14, Istituto Eu Lopeo di Design (72) Inventor Emanuele de Dominici Milan, Italy 20141 , Via Pietrasanta 14, Istituto Europeo di Design (72) Inventor Akihito Yoshiya 7-1, Akitacho, Takatsuki-shi, Osaka Sunstar Giken Co., Ltd. (72) Inventor Kyosuke Kokatsu Osaka 7-1, Akita-cho, Takatsuki-shi Sunstar Giken Co., Ltd. (72) The inventor Fumi Futara 7-1, Akita-machi, Takatsuki-shi, Osaka Sunstar Giken Co., Ltd. 3D012 BH02 BH04

Claims (20)

[Claims] 1. A power-assisted bicycle for applying auxiliary power in accordance with a pedaling force acting on a drive shaft, comprising: a first frame extending rearward from a handle shaft frame; and a lower side of the first frame. A second frame extending rearward from the handle shaft frame, a third frame connecting the first frame and the second frame, and a first frame, a second frame, and a third frame. A power assisted bicycle, comprising: a cover housing that covers the defined closed area. 2. The power assisted bicycle according to claim 1, wherein an extension of a saddle frame for supporting the saddle intersects the closed area. 3. The power assisted bicycle according to claim 1, wherein the drive unit that provides the auxiliary power is housed inside the cover housing. 4. The power-assisted bicycle according to claim 3, wherein a power supply of the drive unit is housed inside the cover housing. 5. The power assisted bicycle according to claim 3, wherein a side surface of the drive unit projects from the cover housing to support the cover housing. 6. The power-assisted bicycle according to claim 3, wherein the drive unit is mounted on the third frame. 7. A lower end of a saddle frame for supporting a saddle is connected to the drive unit.
The power-assisted bicycle described in 1. 8. The power assisted bicycle according to claim 1, wherein the first frame is extended to a position near a rear wheel hub. 9. The power assisted bicycle according to claim 1, wherein a rear end of the second frame is connected to a support portion of the drive shaft. 10. The power assisted bicycle according to claim 9, wherein a lower end of the third frame is connected to a support of the drive shaft, and an upper end of the third frame is connected to the first frame. 11. The power assisted bicycle of claim 1, wherein the cover housing at least partially covers a main sprocket for transmitting pedal effort to a rear wheel. 12. The power assisted bicycle according to claim 1, wherein a storage pocket is provided at an upper portion of the cover housing. 13. The cover housing according to claim 1, wherein the cover housing is made of a lightweight, high-strength plastic material.
A power assisted bicycle according to any one of the preceding claims. 14. The plastic material is a colorless or colored transparent material or an opaque material provided with at least one of a color and a graphic pattern.
3. The power-assisted bicycle according to 3. 15. The power-assisted bicycle according to claim 1, wherein the cover housing is configured by attaching reinforcing plates from both right and left sides of the closed area. 16. A main sprocket provided with a chain, and a drive sprocket connected to a torque output shaft of the drive unit, wherein the drive sprocket is adapted to fit the main sprocket to the chain. The power-assisted bicycle according to any one of claims 1 to 15, wherein the power-assisted bicycle is arranged so as to fit into the chain portion together with the main sprocket from inside the chain. 17. A one-way clutch means for connecting said drive shaft and said main sprocket so as to transmit substantially only one-way rotation of said drive shaft to a main sprocket, and said pedal of said one-way clutch means. The detection device according to any one of claims 1 to 16, further comprising: a detection unit configured to detect a physical quantity that is changed by deformation according to a treading force; and a control unit configured to control the auxiliary power based on at least the physical quantity detected by the detection unit. The power assisted bicycle according to claim 1. 18. A bicycle, comprising: a first frame extending rearward from a handle shaft frame; a second frame aligned with a lower side of the first frame and extending rearward from the handle shaft frame; A bicycle, comprising: a third frame connecting between a first frame and the second frame; and a cover housing covering a closed area defined by the first, second, and third frames. 19. The bicycle according to claim 18, wherein an extension of the saddle frame for supporting the saddle intersects the closed area. 20. The bicycle according to claim 18, wherein the cover housing is configured by attaching reinforcing plates from left and right sides of the closed area, respectively.