JPH10316081A - Driving force auxiliary device for bicycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize structure compact, lightweight, low in cost and high in transmission efficiency regardless of torque fluctuation by changing contact pressure between a guide roller and the outer peripheral surface of a wedge roller and between a rotary shaft and the inner peripheral surface of an outer ring 20 according to torque to be transmitted, and omitting a one-way clutch for preventing an electric motor from becoming resistance in the nondepressed state of a pedal. SOLUTION: The outer peripheral surface of a rotary shaft 4 and the inner peripheral surface of an outer ring 20 are decentered to change the width dimension of internal space 27 existing between both peripheral surface over a circumferential direction. At the time of torque transmission, a wedge roller is displaced to a narrower width dimension part of the internal space 27 so as to increase contact pressure between a guide roller 18c and the outer peripheral surface of the wedge roller and between the rotary shaft 4 and the inner peripheral surface of the outer ring 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION A bicycle driving force assisting device according to the present invention is incorporated in a driving system of an electric assisting bicycle capable of reducing a pedaling force, and reduces the number of rotations of a rotating shaft of an electric motor and transmits the rotation to a pedal shaft. Use it for

[0002]

2. Description of the Related Art The power of an electric motor is used to reduce the pedaling force so that a person without power can climb a hill.
2. Description of the Related Art Electric assisted bicycles that reduce the fatigue of bicycle riders have begun to spread in recent years. Such a structure of the electric assist bicycle is described in, for example, Japanese Patent Application Laid-Open No. 7-95744. As shown in FIG. 15, a bicycle driving force assist device incorporated in an electric assist bicycle described in this publication has a pedal 1 (see FIG. 1 showing an embodiment of the present invention).
Is applied to the pedal shaft 3 that is rotationally driven via the crank 2 by adding a driving force of a magnitude corresponding to the torque applied via the pedal 1 to the torque applied via the pedal 1. Things.

Such a bicycle driving force assisting device includes a battery (not shown), an electric motor 5 (see FIGS. 1, 2, and 5) for rotating a rotating shaft in a predetermined direction based on power supplied from the battery. A speed reducer 31 is provided between the rotation shaft 4 of the electric motor 5 and the pedal shaft 3. The speed reducer 31 includes a planetary roller type speed reducer 32. As described above, the bicycle driving force assist device includes the planetary roller type speed reducer 32
The reason for using 1 is as follows.

First, in order to ensure the efficiency of the electric motor 5, extend the life of the battery, and increase the traveling distance (the distance that can travel with auxiliary power, the same applies throughout the specification). It is necessary to rotate the electric motor 5 at high speed. On the other hand, the rotational driving force applied to the pedal shaft 3 needs to be relatively low in speed and large in torque.
Therefore, a speed reducer 31 is provided between the electric motor 5 and the pedal shaft 3 to reduce the rotation speed of the rotary shaft 4 of the electric motor 5 and increase the torque, and transmit this torque to the pedal shaft 3. I do it.

[0005] A planetary roller type speed reducer 32 is provided at the first stage of the speed reducer 31 to prevent the speed reducer 31 from generating unpleasant noise. That is, a gear type speed reducer such as a planetary gear type speed reducer has good transmission efficiency, but generates harsh high-frequency noise when operated at high speed. Therefore, a planetary roller type speed reducer 32 with less noise is arranged at the first stage of the speed reducer having the fastest operation speed to reduce the noise generated when the speed reducer 31 is operated. Incidentally, the driving force assisting device for a bicycle described in the above-mentioned Japanese Patent Application Laid-Open No. 7-95744 has the planetary roller type speed reducer 3 in the first stage.
2, a bevel gear type speed reducer 33 is provided at the middle stage, and a planetary gear type speed reducer 34 is provided at the last stage. A one-way clutch 35 such as a roller clutch is provided between the planetary roller type speed reducer 32 and the bevel gear type speed reducer 33, and the electric motor 5
The rotation force can be freely transmitted only from the pedal shaft 3 to the pedal shaft 3. The one-way clutch 35 disconnects the pedal shaft 3 and the rotating shaft 4 of the electric motor 5 in a state where the one-way clutch 35 runs without stepping on the pedal 1 such as during coasting or downhill running. Has the function of preventing the resistance to running.

The planetary roller type speed reducer 32 incorporated in the bicycle driving force assisting device described in Japanese Patent Application Laid-Open No. 7-95744 is fixed so as to cover the end of the rotating shaft 4 of the electric motor 5. Housing 36, four support shafts 37, 37 arranged in parallel with the rotation shaft 4 inside the housing 36 around the rotation shaft 4, and the support shafts 37, 37 rotate the support shafts 37, 37. Freely supported 4
It comprises a plurality of planetary rollers 38, 38 and an outer ring 39 having an inner peripheral surface having a cylindrical surface and fixed to a portion surrounding the planetary rollers 38, 38 inside the housing 36. Then, the connecting member 40 supporting each of the support shafts 37, 37
Can freely function as an output shaft of the planetary roller type speed reducer 32, and the revolving motion of each of the planetary rollers 38, 38 can be taken out as a rotation output of the planetary roller type speed reducer 32. Further, the outer peripheral surface of each of the planetary rollers 38 is in contact with the outer peripheral surface of the rotating shaft 4 of the electric motor 5 and the inner peripheral surface of the outer ring 39.

[0007]

SUMMARY OF THE INVENTION As mentioned above,
In the case of the bicycle driving force assisting device described in JP-A-95744, it is difficult to increase the transmission efficiency of the planetary roller type speed reducer 32 over the entire range. Has become an obstacle. The reason is as follows.

In order to ensure the transmission efficiency of the planetary roller type speed reducer 32, the contact portion between the outer peripheral surface of each of the planetary rollers 38, 38, the outer peripheral surface of the rotating shaft 4 and the inner peripheral surface of the outer ring 39 slides. It is necessary to avoid it. Also, in order to prevent these contact portions from slipping, each of the contact portions must be one of
It is necessary to increase the contact pressure between the peripheral surfaces of each pair. Therefore, in the case of the planetary roller type speed reducer 32 incorporated in the conventional bicycle driving force assist device, the planetary rollers 3 are located between the outer peripheral surface of the rotating shaft 4 and the inner peripheral surface of the outer ring 39.
8, 38 are press-fitted by interference fit to secure the contact pressure of each contact portion.

On the other hand, when it is assumed that the contact pressure is constant, the greater the torque transmitted through the planetary roller type speed reducer 32, the more easily the respective contact portions slide. For this reason, conventionally, for example, when climbing a steep slope, the contact pressure is regulated so that the contact portions do not slip even when the torque transmitted through the planetary roller type speed reducer 32 is maximized. (Bigger). However, when the contact pressure between the peripheral surfaces that are in rolling contact is increased, the rolling resistance increases, and the power loss in the planetary roller type speed reducer 32 increases.

More specifically, as in the case of running at a constant speed on a flat ground, the torque transmitted through the planetary roller type speed reducer 32 is small, and even if the contact pressure is low, slippage occurs at each of the contact portions. Even if there is no possibility that the planetary roller type speed reducer 3
2 has a large internal loss. For this reason, the transmission efficiency at the time of constant speed running on flat ground, which is the most running state, is poor, and the power consumption of the battery for supplying power to the electric motor 5 is remarkable. As a result, it becomes difficult to increase the traveling distance of the electric assist bicycle. In view of such circumstances, the bicycle driving force assist device of the present invention employs a traction roller type speed reducer having a structure different from that of the planetary roller type speed reducer 32, and includes various components constituting the traction roller type speed reducer. The structure reduces the battery consumption by adjusting the contact pressure of the contact portion between the outer peripheral surface of the traction roller, the outer peripheral surface of the rotating shaft, and the inner peripheral surface of the outer ring according to the torque to be transmitted. However, the present invention was invented in order to increase the traveling distance of the electric assist bicycle.

[0011]

A bicycle driving force assisting device according to the present invention is similar to the bicycle driving force assisting device described in Japanese Patent Application Laid-Open No. 7-95744 described above. And a battery from the battery to apply a driving force of a magnitude corresponding to the torque applied through the pedal to the pedal shaft that is rotationally driven through the pedal, in addition to the torque applied through the pedal. An electric motor for rotating a rotating shaft in a predetermined direction based on energization, and a reduction gear provided between the rotating shaft of the electric motor and the pedal shaft are provided. Further, the speed reducer includes a traction roller type speed reducer.

The traction roller type speed reducer is different from the planetary roller type speed reducer incorporated in the bicycle driving force assisting device described in JP-A-7-95744. A housing fixed so as to cover an end of the shaft, and a plurality of (preferably, a plurality of (preferably, a plurality of) housings arranged around the rotation shaft inside the housing in parallel with the rotation shaft and not revolving around the rotation shaft. Three or more) support shafts, a plurality (preferably three or more) of traction rollers rotatably supported by the respective support shafts, and a portion provided inside the housing and surrounding the traction rollers. An outer ring having at least an inner peripheral surface as a cylindrical surface, and an output concentric with the outer ring, one end of which is connected and fixed to the outer ring and rotatably supported by the housing. And a shaft. An outer peripheral surface of each of the traction rollers is brought into contact with an outer peripheral surface of a portion rotating together with the rotation shaft and an inner peripheral surface of the outer ring.

In particular, in the driving force assisting device for a bicycle according to the present invention, the center of the rotating shaft and the center of the output shaft and the outer ring are eccentric, so that the outer peripheral surface of the portion that rotates together with the rotating shaft is formed. The width dimension of the internal space existing between the outer ring and the inner peripheral surface and provided with the respective traction rollers is made uneven in the circumferential direction. At the same time, at least one traction roller of the plurality of traction rollers is at least slightly displaceable in the circumferential direction of the internal space and is supported as a wedge roller, and the remaining traction rollers are used as guide rollers. I have. Then, when the rotating shaft and the outer ring rotate in the predetermined direction, at least one of the wedge rollers serves as the wedge roller.
The traction rollers are movable toward a narrow portion of the internal space.

[0014]

In the bicycle driving force assisting device of the present invention constructed as described above, the rotation of the rotating shaft of the electric motor is controlled by the outer circumferential surface of the portion rotating with the rotating shaft and the outer circumferential surfaces of the plurality of traction rollers. Is transmitted to each of these traction rollers via an inner diameter side contact portion which is a contact portion of the traction roller. Further, the rotation of each of the traction rollers is transmitted to the outer ring via an outer-diameter-side contact portion that is a contact portion between the outer peripheral surface of each of the traction rollers and the inner peripheral surface of the outer ring. Then, the output shaft coupled to and fixed to the outer ring rotates to apply auxiliary power to the pedal shaft.

[0015] When the pedal is depressed, torque is applied to the pedal shaft, and based on the energization of the electric motor,
When the rotating shaft and the outer ring rotate in a predetermined direction, at least one traction roller, which is a wedge roller,
In the internal space existing between the outer peripheral surface of the rotating shaft and the inner peripheral surface of the outer ring, the inner space moves toward a narrow portion of the inner space. As a result, at least one of the wedge rollers
The outer peripheral surface of each of the traction rollers strongly presses the outer peripheral surface of the rotating shaft and the inner peripheral surface of the outer ring, and the inner peripheral side contact which is a contact portion between the outer peripheral surface of the traction roller and the outer peripheral surface of the rotating shaft. The contact pressure of the contact portion and the outer diameter side contact portion, which is the contact portion between the outer peripheral surface of the traction roller and the inner peripheral surface of the outer ring, increases. As a result, the contact pressure of the inner and outer contact portions increases, and at least one of the rotating shaft and the outer ring slightly displaces in the respective diametrical directions. An inner diameter side contact portion that is a contact portion between the outer peripheral surface of the roller and the outer peripheral surface of the rotation shaft, and an outer diameter side that is a contact portion between the outer peripheral surface of the remaining traction roller and the inner peripheral surface of the outer ring. The contact pressure of the contact portion increases.

The force for moving at least one traction roller, which is the wedge roller, toward the narrow portion of the internal space in the internal space is the force of the torque transmitted from the rotating shaft to the outer ring. It changes according to the size. That is, the greater the torque, the greater the force, and the greater the contact pressure of both the inner and outer diameter contact portions. Conversely, when the torque is small, the contact pressure of both the inner and outer diameter contact portions is small.

As described above, according to the bicycle driving force assist device of the present invention, when the torque transmitted via the traction roller type speed reducer constituting the speed reduction device is small, the contact pressure of each of the contact portions is reduced. When the torque is large, the contact pressure of each contact portion is increased. Therefore, even when the transmitted torque is large, the respective contact portions can be effectively prevented from slipping, and the rolling resistance acting on each of the contact portions when the transmitted torque is small can be reduced. As a result, the transmission efficiency of the traction roller type speed reducer can be increased over the entire range, the consumption of the battery energizing the electric motor can be suppressed, and the traveling distance of the electric assist bicycle can be increased.

[0018]

1 to 3 show a first embodiment of the present invention. The driving force assisting device for a bicycle according to the present invention is characterized in that the contact pressure of each contact portion is changed in accordance with the torque of the rotational driving force transmitted via the traction roller type speed reducer. Regardless of torque fluctuation,
The structure is for maintaining a high transmission efficiency of the traction roller type speed reducer. Therefore, the following description focuses on the structure and operation of the traction roller type speed reducer.

The bicycle driving force assisting device of the present invention is shown in FIG.
As schematically shown in FIG. 1, when a pedal 1 is depressed, a driving force having a magnitude corresponding to a torque applied via the pedal 1 is applied to a pedal shaft 3 which is rotationally driven via a crank 2. It adds in addition to the torque applied via For this purpose, the bicycle driving force assisting device according to the present invention includes a battery (not shown), an electric motor 5 that rotates the rotating shaft 4 in a predetermined direction based on power supplied from the battery,
A speed reducer 6 is provided between the rotary shaft 4 of the electric motor 5 and the pedal shaft 3. Also, this reduction gear 6
The traction roller type speed reducer 7 provided in the first stage and the gear type speed reducers 8 and 9 provided in the middle stage and the last stage are arranged in series with each other in the power transmission direction. Among them, the middle gear type reduction gear 8 has two large and small helical gears 10a,
0b are engaged with each other. Also, the final stage gear type reduction gear 9
Is formed by meshing two large and small bevel gears 11a and 11b with each other. In addition, these middle-stage and final-stage speed reducers are, for example, a planetary gear type speed reducer, a belt type speed reducer, etc.
Any of various conventionally known reduction gears can be appropriately selected and used.

The traction roller type speed reducer 7 which is a feature of the present invention includes a housing 12 fixed to a frame (not shown) or the like so as to cover an end of the rotary shaft 4 of the electric motor 5. The housing 12 has a bottomed cylindrical main body 13 and a lid 1 for closing a base end opening of the main body 13.
4 The distal end of the rotating shaft 4 of the electric motor 5 is inserted into the housing 12 through a through hole 24 formed at a substantially central portion of the lid 14. The through hole 24 is provided at a position slightly deviated from the center of the lid 14 as described later. A bearing 1 is provided between the inner peripheral surface of the through hole 24 and the outer peripheral surface of the intermediate portion of the rotary shaft 4.
5 are provided.

Further, three support shafts 16 and 16a are arranged inside the housing 12 and around the rotary shaft 4 in parallel with the rotary shaft 4, respectively. That is, one end (upper end in FIG. 2) of each of the support shafts 16 and 16a is supported by the lid 14, and the other end (lower end in FIG. 2).
Are supported by the connecting ring 17. The two support shafts 16, 16a of these three support shafts 16, 16a are press-fitted or substantially fixed at their respective ends into fitting holes provided in the lid 14 and the connecting ring 17. Inserted without sticking. Therefore, these two support shafts 16 and 16 are not displaced in the circumferential direction or the diametrical direction in the housing 12. On the other hand, the remaining one support shaft 16a has both ends slightly displaced relative to the lid 14 and the connecting ring 17 in the circumferential direction of the housing 12 (and further in the diametric direction if necessary). It is freely supported. For this purpose, a part of the lid 14 and a part of the connecting ring 17 which is aligned with both ends of the support shaft 16a is provided with a circular arc-shaped engagement groove or a support shaft 16a which is long in the circumferential direction of the housing 12. A support hole (omitted in FIGS. 1 to 3) having an inner diameter larger than the outer diameter of both ends of the support shaft 16a is loosely engaged with both engagement grooves or support holes. I have. Around the intermediate portion of each of these support shafts 16a, 16, a wedge roller 18a, which is a traction roller, is provided.
And the guide rollers 18b, 18c
(See FIG. 2; omitted in FIG. 3). A part of the connecting ring 17 is connected to the lid 14.
Inner surface (the wedge roller 18a and the guide roller 1)
8b and 18c on the space side, and a part of the lower surface of FIG.
b, 18c and is connected to a protruding portion 28 protruding at a position deviating from 18c.

A cylindrical outer ring 20 with a bottom is rotatably provided inside the housing 12 at a portion surrounding the wedge roller 18a and the guide rollers 18b and 18c. The outer ring 20 includes a cylindrical portion 21 and the cylindrical portion 2.
1 (a lower end in FIG. 2). The inner peripheral surface of the cylindrical portion 21 is a smooth cylindrical surface, which is also formed smoothly.
And the outer peripheral surfaces of the guide rollers 18b, 18c. The outer surface of the disk portion 22 (the side opposite to the space where the wedge roller 18a and the guide rollers 18b and 18c are installed, the lower surface in FIG. 2) is provided at the base end portion of the output shaft 23 (the upper end in FIG. 2). Part). Then, the output shaft 23 is connected to the main body 1 constituting the housing 12.
3 is inserted through a second through hole 25 provided at the center of the housing 3 and protrudes out of the housing 12. The output shaft 23
A bearing 26 is provided between the outer peripheral surface of the portion near the base end and the inner peripheral surface of the second through-hole 25 to rotatably support the outer ring 20 and the output shaft 23 with respect to the housing 12. ing. A portion of the first half (lower half of FIG. 2) of the output shaft 23 protruding outside the housing 12 is provided with a pair of helical gears 10a and 10b constituting the gear type speed reducer 8. The small-diameter helical gear 10b is fixed.

The outer peripheral surfaces of the wedge roller 18a and the guide rollers 18b and 18c are in contact with the outer peripheral surface of the rotating shaft 4 and the inner peripheral surface of the outer ring 20. In particular, in the bicycle driving force assist device of the present invention, the rotating shaft 4
And the centers of the output shaft 23 and the outer ring 20 are eccentric. That is, as described above, the through hole 24 through which the rotary shaft 4 is inserted is provided at a position slightly deviated from the center of the housing 12, whereas the second through hole through which the output shaft 23 is inserted. The hole 25 is provided at the center of the housing 12. Further, the output shaft 23 supported inside the second through hole 25 and the outer ring 20 are concentric with each other. Therefore,
The rotating shaft 4, the outer race 20, and the output shaft 23 are eccentric to each other by an amount of deviation δ of the through hole 24 from the center of the housing 12. The width dimension of the internal space 27 which is present between the outer peripheral surface of the rotary shaft 4 and the inner peripheral surface of the outer ring 20 and in which the wedge roller 18a and the guide rollers 18b, 18c are provided, has a width of this δ. The amount is unequal in the circumferential direction by an amount corresponding to the amount of eccentricity.

As described above, the width of the internal space 27 is made uneven in the circumferential direction, and the wedge roller 18a
The guide rollers 18b and 18c have different outer diameters. That is, the diameters of the wedge roller 18a and the guide roller 18b (small diameter guide roller) located on the side (left side in FIG. 3) where the rotary shaft 4 is eccentric with respect to the outer ring 20 are made equal to each other and relatively small. ing. On the other hand, the guide roller 18c is located on the opposite side (right side in FIG. 3) of the outer ring 20 from the eccentricity of the rotating shaft 4.
The diameter of the (large-diameter guide roller) is larger than that of the wedge roller 18a and the guide roller 18b. And
The outer peripheral surfaces of the three wedge rollers 18a and the guide rollers 18b and 18c, which are traction rollers, are brought into contact with the outer peripheral surface of the rotating shaft 4 and the inner peripheral surface of the outer ring 20. The reduction ratio of the traction roller type reduction gear 7 is determined by the ratio between the outer diameter of the rotating shaft 4 and the inner diameter of the outer ring 20. Therefore, in order to obtain a required reduction ratio, a sleeve is externally fitted and fixed to the end of the rotating shaft 4, and the outer peripheral surface of the sleeve is brought into contact with the outer peripheral surfaces of the wedge roller 18a and the guide rollers 18b, 18c. You can do things.

Of the one wedge roller 18a and the two guide rollers 18b and 18c, each of which is a traction roller,
The support shafts 16 supporting the 8c are fixed in the housing 12 as described above. On the other hand, the support shaft 16a supporting the wedge roller 18a freely supports a slight displacement in the circumferential direction in the housing 12 as described above. Therefore, the wedge roller 18a is also displaceable in the circumferential direction in the housing 12. When the rotation shaft 4 rotates in the predetermined direction, the wedge roller 18a rotatably supported by the single support shaft 16a is movable toward a narrow portion of the internal space 27.

That is, in the illustrated example, when the auxiliary power is applied to the pedal shaft 3, the rotating shaft 4 rotates clockwise as shown by an arrow A in FIG. The direction of assembly of each part is regulated. Therefore, when the auxiliary power is applied, the wedge roller 18a and the guide roller 1
8b and 18c rotate counterclockwise in FIG. 3 around the respective support shafts 16a and 16 as indicated by arrows B and B in FIG. 3, and the outer ring 20 rotates counterclockwise as indicated by arrows C in FIG. Rotate in the direction. Thus, the one wedge roller 18
a rotates as shown by the arrow B, and the wedge roller 18
As a result, the rotating shaft 4 and the outer ring 20, which hold the a from both the inner and outer sides in the diametric direction of the housing 12, rotate as shown by arrows A and C, so that the entire wedge roller 18a is
As shown by an arrow d in FIG. 3, there is a tendency to be displaced clockwise in FIG. That is, the wedge roller 18a receives the force in the direction indicated by the arrow D from the rotating shaft 4 rotating in the direction indicated by the arrow a, and the wedge roller 18a rotates in the direction indicated by the arrow B. The reaction in the direction indicated by the arrow D also receives the reaction from the contact portion. As a result,
When the rotation shaft 4 rotates, the wedge roller 18a
It tends to move toward the narrow part of the internal space 27.

In the case of the bicycle driving force assisting device of the present invention configured as described above, the rotation of the rotating shaft 4 of the electric motor 5 is performed by rotating the outer peripheral surface of the rotating shaft 4 and a wedge roller each of which is a traction roller. 18a and guide roller 1
The power is transmitted to the wedge roller 18a and the guide rollers 18b, 18c via the respective inner diameter side abutting portions 29, 29, which are abutting portions of the outer peripheral surfaces of the 8b, 18c. Further, these wedge rollers 18a and guide rollers 18b, 18c
The rotation of the outer ring 20 is performed through the outer diameter side abutting portions 30, 30 which are abutting portions between the outer peripheral surfaces of the wedge roller 18a and the guide rollers 18b, 18c and the inner peripheral surface of the outer ring 20. Transmitted to. Then, the output shaft 23 fixedly connected to the outer ring 20 rotates. The rotation of the output shaft 23 is further transmitted to the pedal shaft 3 via the pair of gear type speed reducers 8 and 9 to apply auxiliary power to the pedal shaft 3.

When the rotary shaft 4 and the outer ring 20 rotate in a predetermined direction, a wedge roller 18a rotatably supported by a single support shaft 16a causes the outer peripheral surface of the rotary shaft 4 and the outer ring 2 to rotate.
In the inner space 27 existing between the inner space 27 and the inner peripheral surface of the inner space 0, the inner space 27 moves in the two arrow directions in FIG. As a result, the outer peripheral surface of the wedge roller 18a rotatably supported by the one support shaft 16a strongly presses the outer peripheral surface of the rotary shaft 4 and the inner peripheral surface of the outer ring 20. And an inner diameter side contact portion 29 which is a contact portion between the outer peripheral surface of the wedge roller 18a and the outer peripheral surface of the rotary shaft 4, and
The contact pressure of the outer diameter side contact portion 30, which is the contact portion between the outer peripheral surface of the wedge roller 18a and the inner peripheral surface of the outer ring 20, increases.

When the contact pressure between the inner and outer contact portions 29 and 30 with respect to one wedge roller 18a increases, each is a member pressed by the outer peripheral surface of the wedge roller 18a. The rotating shaft 4 and the outer ring 20
At least one of the members is slightly displaced in the respective diametrical direction based on an assembling gap or elastic deformation. As a result, two inner-diameter-side contact portions 29, 29, which are contact portions between the outer peripheral surfaces of the guide rollers 18b, 18c and the outer peripheral surface of the rotary shaft 4, which are the remaining two traction rollers, and Guide rollers 18b, 1
The contact pressure of the two outer diameter side contact portions 30, 30 which is the contact portion between the outer peripheral surface of the outer ring 8b and the inner peripheral surface of the outer ring 20, increases.

The force for moving the wedge roller 18a, which is rotatably supported by the single support shaft 16a, toward the narrow portion of the internal space 27 in the internal space 27 is applied to the rotary shaft 4a. Changes according to the magnitude of the torque transmitted to the outer race 20 from the above. That is, the torque applied from the pedal 1 to the pedal shaft 3 increases, and the greater the driving torque of the rotating shaft 4 of the electric motor 5 based on the signal from the sensor detecting this torque, the larger the wedge roller 18a Is increased toward the narrow portion of the internal space 27. And, as this force increases, the inner and outer diameter side contact portions 2
The contact pressure at 9 and 30 increases. Conversely, when the driving torque is small, the contact pressures of the inner and outer contact portions 29 and 30 are small.

As described above, according to the bicycle driving force assisting device of the present invention, when the torque transmitted via the traction roller type speed reducer 7 constituting the speed reducing device 6 is small, each of the contact portions 29, The contact pressure of the contact portions 29 and 30 is increased when the contact pressure of the contact portions 30 and 30 is reduced and the torque is large. Therefore, even when the transmitted torque is large, the contact portions 29 and 30 are effectively prevented from slipping, and when the transmitted torque is small, the contact portions 2 and 30 are effectively prevented from slipping.
The rolling resistance acting on 9, 9 can be reduced. As a result, the transmission efficiency of the traction roller type speed reducer 7 can be increased over the entire range, the consumption of the battery for energizing the electric motor 5 can be suppressed, and the travel distance of the electric assist bicycle can be increased.

For example, FIG. 4 shows the transmission efficiency of the traction roller type reduction gear in the torque range transmitted by the bicycle driving force assist device to which the present invention is applied. The horizontal axis represents the transmission torque, and the vertical axis represents the transmission efficiency.
Further, a curve α with continuous circles indicates the transmission efficiency of the driving force assisting device for a bicycle of the present invention, and a curve β with continuous triangles indicates
The transmission efficiency of the driving force assist device for a bicycle incorporating a traction roller type speed reducer to which a contact pressure is applied so as not to cause a slip even in the maximum torque range without having an eccentric structure as in the present invention is shown. ing. The oblique lattice portion is a normal torque region when the vehicle travels at a constant speed on flat ground. As is apparent from FIG. 4, according to the bicycle driving force assisting device of the present invention, it is possible to improve the transmission efficiency in the normal torque range by about 2 to 5 points (%) and to extend the traveling distance accordingly. Will be possible.

In practicing the present invention, a return spring is attached to one support shaft 16a which is displaced in the circumferential direction, if necessary, and the elastic force in the direction of returning to the neutral position is provided on the support shaft 16a. Is given. In the neutral position, the outer peripheral surface of the wedge roller 18a supported by the support shaft 16a is lightly brought into contact with the outer peripheral surface of the rotary shaft 4 and the inner peripheral surface of the outer ring 20. Further, the eccentricity δ and the support shaft 16a
The amount of displacement in the circumferential direction is determined by design in consideration of the contact pressure necessary for the contact portions 29 and 30 during torque transmission. Further, in the case of a traction roller type reduction gear incorporated in the bicycle driving force assist device of the present invention, during coasting,
In a state where the rotating shaft 4 does not rotate and the outer ring 20 rotates, such as when traveling downhill, the wedge roller 18a tends to move to a wide portion of the internal space 27. As a result, the wedge roller 18a and the guide roller 18
b, 18c, the outer peripheral surface of the rotary shaft 4 and the outer ring 2
0, the contact pressure with the inner peripheral surface becomes low, and the rotation of the outer ring 20 is not transmitted to the rotating shaft 4. Therefore, when implementing the present invention, it is also possible to omit the one-way clutch, which is required in the conventional structure.

FIGS. 5 to 7 show a second embodiment of the present invention, in which a one-way clutch is omitted by utilizing the characteristics of the traction roller type transmission as described above. Is shown. In the case of this example, three support shafts 16,
The support 16 a is supported so as to bridge between the inner surface (the lower surface in FIG. 5) of the lid 14 constituting the housing 12 and the connecting ring 17. Of the three support shafts 16 and 16a, two support shafts 1 for supporting the guide rollers 18b and 18c
Reference numerals 6 and 16 are fitted and fixed to the lid 14 and the connecting ring 17 so as not to move. On the other hand, both ends of the support shaft 16a that rotatably supports the wedge roller 18a around the intermediate portion are larger than the outer diameter of the support shaft 16 formed on the inner surface of the lid 14 and the connection ring 17. The support hole 41 having a large inner diameter is loosely engaged.

Further, a cylinder hole 42 is formed in a part of the lid 14 so as to be open on the inner peripheral surface of the support hole 41. Such a cylinder hole 42 is formed at the same time as, for example, when the lid 14 is formed by die casting of an aluminum alloy or the like. When the cylinder hole 42 is formed in this manner, the design of the small traction roller type speed reducer 7 is facilitated by effectively utilizing the axial dimension of the lid 14. In any case, the elastic member 43 having a weak elasticity such as a compression coil spring is provided in the cylinder hole 42.
And a pressing piece 44 provided with elasticity in a direction protruding from the inner peripheral surface of the support hole 41 by the elastic material 43. Then, one end surface of the pressing piece 44 is elastically abutted against the outer peripheral surface of the support shaft 16a supporting the wedge roller 18a. The support shaft 16a and the wedge roller 18a supported on the intermediate portion of the support shaft 16a are connected to an inner space between the outer peripheral surface of the rotary shaft 4 and the inner peripheral surface of the cylindrical portion 21 forming the outer ring 20. 27, lightly pressed toward the narrow portion. The pressing piece 4
Numeral 4 is provided to prevent the elastic member 43, which is a compression coil spring, from falling down and to set the elastic load applied to the support shaft 16a by the elastic member 43 to an appropriate value. That is, when the elastic member 43 is inclined in the cylinder hole 42, the direction of action of the elastic load by the elastic member 43 shifts, and the elastic load applied to the support shaft 16a may deviate from the set value. On the other hand, if the pressing piece 44 is provided, the elastic member 43 can be prevented from falling down, and the elastic load applied to the support shaft 16a can be regulated to a set value. Although not shown, a flat surface is formed as needed on a portion of the support shaft 16a where the distal end surface of the pressing piece 44 abuts to prevent the support shaft 16a from rotating.

A base end of an output shaft 23 is fixedly connected to an outer surface of a central portion of a disk portion 22 constituting the outer race 20, and the rotational movement of the output shaft 23 is different from that of the conventional structure shown in FIG. Similarly, it can be transmitted to the pedal shaft 3 via a bevel gear type speed reducer 33 at the middle stage and a planetary gear type speed reducer 34 at the last stage. However, in the case of the bicycle driving force assist device of this example,
Unlike the conventional structure shown in FIG. 15, a one-way clutch such as a roller clutch is not provided between the traction roller type speed reducer 7 and the bevel gear type speed reducer 33. That is, the output portion of the traction roller type speed reducer 7 and the input portion of the bevel gear type speed reducer 33 are coupled by concave and convex engagement or integrally, thereby enabling transmission of rotational force in both directions. .

As described above, even if a one-way clutch such as a roller clutch is not provided between the traction roller type speed reducer 7 and the bevel gear type speed reducer 33, the bicycle driving force assist device of the present invention can be used. Is for coasting, downhill running, etc.
The pedal shaft 3 and the rotating shaft of the electric motor 5 are separated in a state where the vehicle travels without stepping on the pedal 1, so that the presence of the electric motor 5 can be prevented from being a resistance to traveling. That is,
As if the vehicle were running without stepping on the pedal 1, the rotating shaft 4
When the outer ring 20 rotates without rotating the wedge roller 18a, the wedge roller 18a tends to move to a wide portion of the internal space 27 against the elasticity of the elastic member 43. As a result, the outer peripheral surfaces of the wedge roller 18a and the guide roller 18b, the outer peripheral surface of the rotary shaft 4 and the outer race 2
0, the contact pressure with the inner peripheral surface is reduced, and
9, 29 and the respective outer diameter side contact portions 30, 30 slide, and the outer ring 2
The rotation of 0 is not transmitted to the rotation shaft 4.

As described above, the one-way clutch is omitted,
Not only can cost reduction based on reduction of component cost be achieved, but also cost reduction can be achieved by facilitating component management and assembly work. Further, since the installation space for the one-way clutch is not required, the size and weight of the driving force assisting device for a bicycle can be reduced. The elastic member 43 and the pressing piece 4 for pressing the wedge roller 18a against the narrow portion of the internal space 27 are provided.
4 is preferably provided between both ends of the support shaft 16a and the lid 14 and the connecting ring 17 if the installation space allows.

In this example (and a third example described below), the compression shaft of the elastic member 43 supports the support shaft 16a, which supports the wedge roller 18a, on the narrow portion of the internal space 27. The pressing elasticity (elastic load) is
Is determined by design according to the magnitude of the rotational force (torque) to be transmitted to the outer ring 20 from the motor. For example, in the case of a power assist device for a bicycle used on a daily basis, the magnitude of the elastic load is
It is preferable to regulate the amount in the range of 150 to 1000 g. When the elastic load is less than 150 g, the contact pressure between the outer peripheral surface of the wedge roller 18a, the outer peripheral surface of the rotary shaft 4 and the inner peripheral surface of the outer ring 20 becomes too small when the bicycle is in a stopped state. Immediately after starting the bicycle, the outer peripheral surface of the wedge roller 18a, the outer peripheral surface of the rotary shaft 4 and the outer ring 2
Slip occurs with the inner peripheral surface of No. 0, and sufficient auxiliary power cannot be obtained. On the other hand, when the elastic load is 1000
If the value exceeds g, the contact pressure becomes too large, and the rolling at the contact portions (the inner contact portions 29, 29 and the outer contact portions 30, 30) between the respective peripheral surfaces is performed. Resistance increases,
Not only does the transmission efficiency of the traction roller type speed reducer 7 decrease, but also the idling torque in a state where the vehicle runs without stepping on the pedal 1 such as during coasting or downhill traveling is increased. Gives discomfort.

That is, the elastic load applied to the wedge roller 18a by the elastic material 43 is applied to the wedge roller 18a when the traction roller type speed reducer 7 is started.
a, the contact pressure between the outer peripheral surface of the shaft a and the outer peripheral surface of the rotary shaft 4 and the inner peripheral surface of the outer ring 20 is ensured. It is necessary to prevent slipping from occurring at portions 29 and 30. When the wedge roller 18a cuts into the narrow portion of the internal space 27 after the start of the traction roller type speed reducer 7, the elastic load by the elastic material 43 is not only unnecessary but also excessive. The above traction roller type speed reducer 7
And the idle torque is increased. Therefore, the magnitude of the elastic load is set to 150 to 100
Restrict to 0g.

The axial clearance of the wedge roller 18a mounted in the internal space 27 is 0.1 to
It is preferable to regulate it to a range of 1.5 mm. The reason for this is
When the support shaft 16a pivotally supporting the wedge roller 18a is inclined with respect to the rotation shaft 4 for some reason,
This is because the inner surface of the internal space 27 and the peripheral edge of the wedge roller 18a are strongly rubbed, so that the wedge roller 18a is not restrained. In addition, the said axial gap is
As shown in FIG. 8, when the wedge roller 18a is displaced in the internal space 27 so that it does not tilt any further, the distance δ between the outer peripheral edge of the end of the wedge roller 18a and the inner surface of the internal space 27. It is.

Next, FIGS. 9 to 13 show a third example of the embodiment of the present invention, which is more specific. Regarding this example, the basic structure itself is the same as the first example shown in FIGS. 1 to 3 or the second example shown in FIGS. 5 to 7. Each part will be described. First, the rotary shaft 4 which is a rotary drive shaft of the electric motor 5 (see FIGS. 1 and 2) and an input shaft of the traction roller type transmission 7 is also used.
Are wedge rollers 18a and guide rollers 18b, 1
Induction hardening is performed only on the outer peripheral surface of the tip (the lower end in FIG. 9) that contacts the outer peripheral surface of 8c. By doing so, wear of the outer peripheral surface of the tip of the rotating shaft 4 is prevented,
In addition, the cost increase and the deformation of the rotating shaft 4 due to the induction hardening process are prevented. The outer peripheral surface of the tip of the rotating shaft 4 subjected to the induction hardening treatment in this manner is polished so that the surface roughness is 0.4a or less. Thus, the wedge roller 18a and the guide roller 18
By smoothing the outer peripheral surface of the tip end of the rotating shaft 4 which is in contact with the outer peripheral surfaces of b and 18c, the oil film between these outer peripheral surfaces which are in contact with each other is protected (an oil film having high strength can be formed). The rotation shaft 4 and the wedge roller 18a
And traction drive between the guide rollers 18b and 18c.

The operation of assembling the rotating shaft 4 to the traction roller type transmission 7 as described above is performed by the outer ring 20 described below.
Inside the wedge roller 18a and the guide roller 1
8b and 18c are assembled. In order to easily perform such assembling work of the rotating shaft 4 and not to damage the outer peripheral surfaces due to the assembling work, when inserting the rotating shaft 4, the wedge roller 18 a is attached to the inner space 27. Displace it to a wider part. For this reason, in the illustrated example, an insertion hole 45 for inserting a rod-shaped tool is provided in a portion of a lid 14a, which will be described later, at a portion facing the outer peripheral surface of the end of the support shaft 16a that supports the wedge roller 18a.
Is provided. When the rotary shaft 4 is inserted, the support shaft 16a is displaced by the tool inserted into the insertion hole 45 to the wide portion against the elasticity of the compression coil spring, which is the elastic member 43, and the wedge roller 18a is displaced. The diameter of the inscribed circle on the outer peripheral surface of each of the guide rollers 18 b and 18 c is set to be larger than the outer diameter of the tip of the rotating shaft 4. Further, in the example shown in the figure, a chamfer 46
Is formed so that the operation of inserting the rotary shaft 4 can be performed more easily. With this configuration, the assembling work of the traction roller type transmission 7 is facilitated, and the cost of the bicycle driving force assist device including the traction roller type transmission 7 can be reduced.

The portion of the rotary shaft 4 near the front end is supported by a clearance fit inside the inner ring constituting the bearing 15. An outer ring constituting the bearing 15 is provided with a through hole 24 formed in a lid 14a constituting a housing 12a described later.
And the through-hole 24 is formed by a missing annular retaining ring 48.
It is trying to keep from getting out of. As described above, the portion of the rotary shaft 4 near the front end of the intermediate portion is fitted to the inner ring of the bearing 15 with a clearance fit, not only to facilitate the operation of inserting the rotary shaft 4 but also to improve the traction. This is also necessary for reliably operating the roller transmission 7. That is, when the wedge roller 18a is displaced to the narrow portion of the internal space 27, the rotating shaft 4 is displaced in the diametric direction, and the outer peripheral surface of the rotating shaft 4 and the rollers 18a, 18b, 1
8c inner diameter side abutting portions 29, 29 which are abutting portions with the outer peripheral surface of 8c
In addition, the inner peripheral surface of the outer ring 20 and each of the rollers 18 described below
The contact pressure of the outer diameter side contact portions 30, 30 which are the contact portions with the outer peripheral surfaces of the a, 18b, 18c is increased. At this time, in order to smoothly perform the displacement in the diameter direction of the rotating shaft 4 and to sufficiently increase the contact pressure of each of the contact portions 29 and 30, the tolerance of the constituent members is taken into consideration. , The gap between the bearings 15
It is necessary to limit the range to 0.010 to 0.2 mm. In this case, the gap of the bearing 15 is defined as the internal gap of the bearing 15, the gap between the inner peripheral surface of the inner race and the outer peripheral surface of the rotary shaft 4, and the bearing 15. 15 is the sum of the gap between the outer peripheral surface of the outer race constituting the outer ring 15 and the inner peripheral surface of the lid 14a described later.

The outer race 20 of the traction roller type transmission 7 is formed by forging a metal material such as carbon steel equivalent to SCr420 which can secure sufficient rigidity and hardness and which can be processed relatively easily. Make by applying.
When the metal material is forged to have a desired shape, a heat treatment for carburizing and quenching for hardening the surface is performed, and then an L3 process (turning after heating) is performed. afterwards,
Only a portion of the inner peripheral surface that comes into contact with the outer peripheral surfaces of the wedge roller 18a and the guide rollers 18b and 18c is ground, and this portion is smoothed (rough) similarly to the outer peripheral surface of the tip of the rotary shaft 4. 0.4a or less). By such processing, the outer ring 20 can be manufactured at low cost while preventing deformation. As another manufacturing method, S53C
After forging a considerable medium-carbon steel, turning it into the desired shape, then induction hardening only the rolling surface,
Alternatively, the rolling surface can be ground after hardening by laser quenching. In the case of induction hardening or laser hardening, since the deformation can be reduced, the grinding process can be omitted.

The disk portion 22 constituting the outer ring 20 as described above
9 is provided on the outer surface (the lower surface in FIG. 9) of the output shaft 23 (FIG. 9).
Upper end). And this output shaft 2
3 is inserted into a bearing 26 inside a second through hole 25 formed in a main body 13a constituting a housing 12a to be described later.
It is rotatably supported by. The outer ring constituting the bearing 26 is fitted inside the second through-hole 25, and is prevented from falling out of the second through-hole 25 by a missing annular retaining ring 48a. The output shaft 23 as described above is connected to the outer ring 20.
May be provided integrally at the time of forging, or may be connected and fixed to the outer ring 20 later. When the connection is fixed later, a mounting hole formed in the center of the outer ring 20 is provided.
For example, a method of internally fitting and fixing the base end of the output shaft 23 by interference fit may be considered. In any case, the output shaft 2
A rotation transmitting member such as a gear and a pulley is externally fitted and fixed to the first half of FIG. 3 (the lower half of FIG. 9) by press fitting, serration engaging, serration engaging with press fitting, key engaging, or the like. By externally fixing the rotation transmitting member to the first half of the output shaft 23 in this manner, the installation space for the second-stage (provided after the traction roller type transmission 7) speed reducer can be reduced.

The main body 13 constituting the housing 12a
a and the lid 14a are both manufactured by die-casting a light alloy such as an aluminum alloy or a magnesium alloy. The main body 13a may be integrally formed with other members such as a casing 47 (see FIG. 5) incorporating other reduction gears such as a bevel gear reduction gear 33 and a planetary gear reduction gear 34. It is possible. As described above, the base end of the output shaft 23 fixed to the outer race 20 is rotatably supported by the bearing 13 on the main body 13a.
Further, the lid 14a may be formed integrally with a component of the electric motor 5, such as an end plate of a motor housing constituting the electric motor 5 (see FIG. 5). As described above, the portion of the rotary body 4 near the front end of the rotary shaft 4 is rotatably supported by the bearing 15 on the lid 14a.

Further, support shafts 16a, 16a for supporting the wedge roller 18a and the guide rollers 18b, 18c are provided.
6 supports one end (the upper end in FIG. 9) on the lid 14a and the other end (the lower end in FIG. 9) on the connecting ring 17. The connecting ring 17 is formed into a shape as shown in FIG. 12 by die-casting a light alloy as described above. That is, the connecting ring 17 has a ring shape as a whole, and screws 49, 49 for connecting and fixing the connecting ring 17 to the protruding portions 28, 28 of the lid 14a at three circumferential positions.
Are formed. In addition, 3 exists between the through holes 50 adjacent to each other in the circumferential direction.
The other end portions of the support shafts 16, 16 supporting the guide rollers 18b, 18c are fitted to the other portion between the two portions by tight fitting or without looseness. Holes 51, 51 are formed. On the other hand, the other end of the support shaft 16a for supporting the wedge roller 18a is loosely engaged with the inner surface of the remaining one portion, and has a sufficiently larger diameter than the support shaft 16a. A bottom support hole 52 is formed. Such a connecting ring 17 can of course be produced by shaving a steel plate. However, since it has a plurality of holes, die casting as described above is more preferable for cost reduction.

Each of the three support shafts 16 and 16a is subjected to a heat treatment (sizzling) for hardening the surface so as to make rolling contact with a rolling surface of a needle constituting a bearing 19 described below. Regardless, sufficient rolling fatigue life can be ensured. Of the three support shafts 16 and 16a, the support shafts 16 and 16 for supporting the guide rollers 18b and 18c have both ends at the lid 14 respectively.
In the fitting hole formed in the connecting ring 17 and the connecting ring 17, an internal fitting may be performed by interference fitting. However, in order to improve the efficiency of the assembling work, one end of each of the support shafts 16 and 16 is simply fixed to the cover 14a by tight fitting, and the other end of each of the support shafts 16 and 16 is fixed. It is preferable that the side is internally fitted into the fitting holes 51, 51 formed in the connecting ring 17 by gap fitting. That is, the support shafts 16, 16 are attached to the lid 14a.
After supporting one end of the support shafts 16,
After the guide rollers 18b and 18c and the wedge roller 18a are externally fitted around the support ring 16a through a bearing 19, the other end of each of the support shafts 16 and 16a is connected to the connection ring 1
If it is supported by the fitting holes 51, 51 and the supporting holes 52 provided in the base member 7 by gap fitting, the assembling work can be performed efficiently.

As described above, the three support shafts 16, which are supported between the lid 14a and the connecting ring 17, are supported.
Around the guide rollers 18b, 18c
And a wedge roller 18 a rotatably supported via a bearing 19. In the case of this example, a radial needle bearing with a retainer is used as the bearing 19.
In the case of a radial needle bearing with a retainer, a plurality of needles constituting the bearing 19 are held inseparably by a retainer.
6 and 16a and the guide rollers 18b and 18
The work of mounting the gap between c and the inner peripheral surface of the wedge roller 18a can be performed efficiently.

As described above, each of the support shafts 16, 16
a guide roller 1 rotatably supported around a
8b, 18c and the wedge roller 18a are made of a hard metal that can secure sufficient hardness, such as high carbon chromium bearing steel such as SUJ2. These rollers 18a to 18c
Is a heat treatment for hardening the surface (Zubuki)
The outer peripheral surfaces of the rollers 18a to 18c are ground by contacting the outer peripheral surface of the rotary shaft 4 and the inner peripheral surface of the outer ring 20. (Surface is 0.4a or less)
To finish. In this way, by smoothing the outer peripheral surfaces of the rollers 18a to 18c, the rotating shaft 4 and the outer ring 20, the wedge roller 18a and the guide roller 18 are formed.
traction drive between the motors b and 18c. The inner peripheral surface of each of the rollers 18a to 18c, which comes into contact with the rolling surface of the needle, and the support shaft 1
The outer peripheral surfaces of the intermediate portions of the rollers 6a and 16a are also fixed to the rollers 18a to 18a.
8c is a smooth surface similar to the outer peripheral surface.

As is clear from the above description of the first and second examples, among the guide rollers 18b and 18c and the wedge roller 18a, each of the guide rollers 18b and 18c is
It rotates only around the support shafts 16, 16, and does not displace in the circumferential direction around the rotation shaft 4. However, the guide rollers 18b, 18c can be slightly displaced in the respective diametrical directions by the displacement of the wedge roller 18c.
A clearance is set in each of the bearings 19 provided between the inner peripheral surface of the support shaft c and the outer peripheral surfaces of the support shafts 16 and 16. or,
The wedge roller 18a rotates around the support shaft 16a and slightly displaces in the circumferential direction around the rotation shaft 4. Since the wedge roller 18a can be displaced by displacing the support shaft 16a itself, the inner peripheral surface of the wedge roller 18a and the support shaft 1a are displaced.
Although it is not necessary to provide a gap in the bearing 19 provided between the bearing 19 and the outer peripheral surface of the guide roller 18b, the guide rollers 18b, 18
In order to share parts between the bearings c and the bearings 16 and 16 and to reduce costs, it is free to provide the above gaps.

The wedge roller 18a and the guide rollers 18b and 18c are provided on both sides in the axial direction.
Thrust washers 53, 53 as shown in FIG. 13 are provided between the inner surface of a and the inner surface of the connecting ring 17. These thrust washers 53, 53 are provided on both sides in the axial direction of the rollers 18a to 18c and the both ends in the axial direction of each needle constituting the bearing 19, and the lid 14a.
And prevents the inner surfaces of the connecting ring 17 from rubbing against each other to smoothly rotate the rollers 18a to 18c and to prevent wear of the components. Incidentally, the thrust washers 53, 53 as described above can be formed in an independent shape for each of the rollers 18a to 18c. Regardless of which shape is adopted, it is also possible to form by punching a metal plate with a press, or to make it by injection molding a synthetic resin. Especially,
If made of synthetic resin with oil resistance and low friction,
Cost reduction and longer life can be achieved.

Further, traction grease is sealed in the housing 12a including the internal space 27.
This traction grease is based on traction oil to which a lithium soap group is added, has a large traction coefficient, and enables transmission of a large rotational force between the rotating shaft 4 and the outer ring 20. In addition, the traction grease has a function of transmitting the rotational force between the rotating shaft 4 and the outer ring 20, and also a function of lubricating the respective contact portions. Therefore, as the above traction grease, those having high consistency (for example, about Uw387) and improved lubricity (fluidity) can be preferably used. However, when the consistency is increased to improve the fluidity, the traction grease easily leaks to the outside unless the performance of the sealing material that partitions the inside and the outside of the housing 12a is improved. Therefore, in consideration of the performance of the sealing material, the consistency of the traction grease is increased by 15%.
It may be reduced to about 0 to 350. By setting the consistency of the traction grease to this level (about 150 to 350), even with the seal rings attached to the bearings 15 and 26, the leakage of the traction grease can be suppressed to a practically acceptable level. . The housing 1
Traction oil may be enclosed in 2a instead of traction grease. In this case, the transmission efficiency of the traction roller type speed reducer 7 can be increased by reducing the stirring resistance. On the other hand, traction oil has a higher fluidity than traction grease and easily leaks. Therefore, it is necessary to improve the performance of the sealing material at the penetrating portions of the rotating shaft 4 and the output shaft 23.

In the conventional bicycle assist device, while the bicycle is stopped or running at a low speed, the same torque as that applied from the pedal 1 to the pedal shaft 3 is applied to the electric motor 5 (see FIG. 1). ) Was controlled to take it out as auxiliary power. That is, as shown in FIG. 14 (A), when a torque of α is applied from the pedal 1 to the pedal shaft 3, the electric motor 5 also generates an auxiliary power of α (the oblique grid portion in FIG. 14 (A)), At a torque of 2α. According to such control, when the bicycle is started, if the pedal is depressed carelessly, a large amount of auxiliary power is suddenly applied, which may cause a slight shock. In order to alleviate the shock generated at the time of starting due to such a cause, as shown in FIG. 14 (B), at the time of starting and immediately after starting, the magnitude of the torque applied from the pedal 1 to the pedal shaft 3 is reduced. It is conceivable to reduce the ratio of the auxiliary power applied from the electric motor. That is, the starting is performed based on the torque applied to the pedal shaft 3 from the pedal 1. As the speed of the bicycle increases, the magnitude of the torque applied from the pedal 1 to the pedal shaft 3 gradually increases.
By increasing the ratio of the auxiliary power applied from the electric motor, the occurrence of the shock can be prevented. For example, the following Tables 1 and 2 exemplify control patterns as shown in FIG.

[0056]

[Table 1]

[0057]

[Table 2]

Of these Tables 1 and 2, Table 1 shows FIG.
(B) shows three examples of speed patterns at three points α, β, and γ, and Table 2 shows four examples of torque patterns at two points α, β, respectively. The unit in Table 1 is km / h, and the unit in Table 2 is kg · m. The control is performed by appropriately combining the three patterns shown in Table 1 and the four patterns shown in Table 2. Also, a changeover switch is provided on the bicycle, and FIG.
Including the control as shown in (A), the rider of the bicycle can select various control states. Regarding the torque, the value of δ when the traveling speed is increased to some extent is (0.8 to 1.0) γ, and β is (α + γ) / 2 to
(Α + γ) / 4. The speed at the point δ where the supply of the auxiliary power is stopped is set to about 20 to 30 km / h.
As described above, the magnitude of the auxiliary power is changed in accordance with the running speed of the bicycle by adjusting the amount of power supplied to the electric motor 5 and by changing the wedge roller 18a in a narrow portion of the internal space 27. It can also be done by changing the pressing force. However, in this case, the wedge roller 18a is pressed by a resilient pressing means such as a solenoid, which can adjust the pressing force.

[0059]

The bicycle driving force assisting device of the present invention is constructed and operates as described above, so that the transmission efficiency can be improved, the consumption of the battery can be suppressed, and the traveling distance of the electric assisted bicycle can be increased. It can contribute to the realization of an electric assisted bicycle that is easier to use. Further, if necessary, the one-way clutch can be omitted to reduce costs and reduce the size and weight.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a first example of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a schematic cross-sectional view taken along line BB of FIG.

FIG. 4 is a diagram showing the difference between the transmission efficiency of a traction roller type speed reducer incorporated in the bicycle driving force assist device of the present invention and the transmission efficiency of a conventionally used traction roller type speed reducer.

FIG. 5 is a partial sectional view showing a second example of the embodiment of the present invention.

6 is a cross-sectional view taken along the line CC of FIG. 5, showing a state in which a part is omitted and a cutting position is partially changed.

FIG. 7 is an enlarged view of a portion D in FIG. 6;

FIG. 8 is a schematic sectional view showing a state in which a wedge roller is inclined.

FIG. 9 is a partial sectional view showing a third example of the embodiment of the present invention.

FIG. 10 is a bottom view as viewed from below in FIG. 9;

FIG. 11 shows a state where the cutting position is partially changed,
EE sectional view of FIG.

12A and 12B show a connecting ring, wherein FIG. 12A is a view as viewed from below in FIG. 9, and FIG. 12B is a sectional view taken along line FF of FIG.

13A and 13B show a thrust washer, wherein FIG. 13A is a view as viewed from below in FIG. 9, and FIG. 13B is a sectional view taken along line GG of FIG.

FIG. 14 is a diagram showing two examples of the relationship between the traveling speed and the magnitude of the auxiliary power.

FIG. 15 is a partial cross-sectional view showing one example of a conventional structure.

[Explanation of symbols]

 Reference Signs List 1 pedal 2 crank 3 pedal shaft 4 rotating shaft 5 electric motor 6 reduction gear 7 traction roller reduction gear 8, 9 gear reduction gear 10a, 10b shelving gear 11a, 11b bevel gear 12 housing 13 main body 14 cover 15 bearing 16 , 16a Support shaft 17 Connecting ring 18a Wedge roller 18b, 18c Guide roller 19 Bearing 20 Outer ring 21 Cylindrical part 22 Disk part 23 Output shaft 24 Through hole 25 Second through hole 26 Bearing 27 Internal space 28 Projection 29 Inner diameter side contact Contact part 30 Outer diameter side contact part 31 Reduction gear 32 Planetary roller type reduction gear 33 Bevel gear type reduction gear 34 Planetary gear type reduction gear 35 One-way clutch 36 Housing 37 Support shaft 38 Planetary roller 39 Outer ring 40 Connecting member 41 Support hole 42 Cylinder hole 43 Elastic material 44 Pressing piece 45 Insertion hole 46 Chamfer 47 Pacing 48,48a retaining ring 49 screw 50 through hole 51 fitting hole 52 support hole 53 thrust washer

Claims (3)

[Claims] 1. A driving force having a magnitude corresponding to a torque applied via the pedal is added to a torque applied via the pedal to a pedal shaft which is rotationally driven via a crank by depressing the pedal. A battery, an electric motor that rotates a rotating shaft in a predetermined direction based on power supply from the battery, and a reduction gear provided between the rotating shaft of the electric motor and the pedal shaft, The speed reducer includes a traction roller type speed reducer.The traction roller type speed reducer includes a housing fixed so as to cover an end of the rotation shaft, and a rotation shaft of the rotation shaft inside the housing. A plurality of support shafts arranged in a peripheral portion in parallel with the rotation axis,
A plurality of traction rollers rotatably supported by the respective support shafts; an outer ring provided at a portion surrounding the traction rollers inside the housing and having at least an inner peripheral surface as a cylindrical surface; and an outer ring concentric with the outer ring. An output shaft rotatably supported by the housing and having one end coupled and fixed to the outer ring, the outer peripheral surface of each of the traction rollers, the outer peripheral surface of the portion rotating with the rotary shaft and the outer ring In a bicycle driving force assist device that is configured to be brought into contact with an inner peripheral surface, by eccentricizing the center of the rotation shaft and the center of the output shaft and the outer ring,
The width dimension of the internal space that is present between the outer peripheral surface of the portion that rotates together with the rotating shaft and the inner peripheral surface of the outer ring and in which the traction rollers are provided is made uneven in the circumferential direction. At least one of the plurality of traction rollers is at least slightly displaceable in the circumferential direction of the internal space and is supported as a wedge roller, and the remaining traction rollers are used as guide rollers. By doing so, when the rotating shaft and the outer ring rotate in the predetermined direction, at least one traction roller serving as the wedge roller is movable toward a narrow portion of the internal space. Power assist device for bicycles. 2. A housing for supporting a plurality of support shafts so as to bridge between an inner surface of a housing and a connecting ring, and supporting both ends of a support shaft rotatably supporting a wedge roller around an intermediate portion. The wedge roller is loosely engaged with a support hole formed in the inner surface of the connection ring and the connection ring, and the wedge roller is elastically provided between the housing or the connection ring and the outer peripheral surface of the end of the support shaft. The bicycle driving force assisting device according to claim 1, wherein the device is lightly pressed toward a narrow portion. 3. The bicycle driving force assisting device according to claim 2, wherein the elastic member is a compression coil spring, and the elastic load applied to the wedge roller by the compression coil spring is 150 to 1000 g.