JPH10119873A - Power unit for power assisted bicycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a structure for a pedaling force detecting device much more, also reduce the number of part items, and simply assembled it to the power unit for a power assisted bicycle. SOLUTION: In the power unit 20 for a power assisted bicycle where a resultant force shaft is coaxially disposed so as to be linked there-to by way of a sun gear through a one-way clutch and the planetary gear of a planetary gear mechanism with respect to a crankshaft 21 to be rotated by the pedaling force of a rider, and with respect to the ring gear of the planetary dear mechanism where the ring gear is supported in such a way that the planetary gear mechanism can be rotated, a means is provided, which detects pedaling force based on a reaction caused when the crankshaft 21 is linked to the resultant force shat, a concurrently an electrically driven motor 30 which outputs auxiliary power in response to pedaling force detected by the pedaling force detecting means, is so disposed as to allow its rotation to be transmitted to the resultant force shaft by way of a transmitting means, the pedaling force detecting means is made up by providing a load sensor 60 which receives pressing force caused by an arm part 55d so as to detect load by means of a strain gauge with respect to the arm part 55d formed in the ring gear 55b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power unit for an auxiliary powered bicycle in which an auxiliary driving force is provided by an electric motor in accordance with human power when an occupant depresses a pedal. The present invention relates to a power unit for an auxiliary powered bicycle in which a treading force detecting means for detecting a required force is integrally provided.

[0002]

2. Description of the Related Art In a hybrid powered bicycle of a power assist system, that is, a bicycle with an auxiliary power, in which an auxiliary driving force is provided by an electric motor in accordance with the magnitude of human power when the occupant depresses a pedal, the occupant's pedaling force is applied. A rotating shaft, a resultant shaft in which a drive sprocket of a vehicle driving force transmission chain is fixed to an outer end, a human-power transmitting means for transmitting rotation of the crankshaft to the resultant shaft via a one-way clutch and a planetary gear mechanism, A treading force detecting means for detecting a treading force by a reaction force generated when the crankshaft and the resultant shaft are interlocked; an electric motor for generating an auxiliary power corresponding to the treading force detected by the treading force detecting means; And an auxiliary power transmitting means for transmitting power to the power unit.

In such a conventional power unit of an auxiliary powered bicycle, the crankshaft and the resultant shaft are linked from the planetary gear of the planetary gear mechanism through one of the sun gear or the ring gear, whereas the planetary gear is The other of the sun gear or the ring gear of the mechanism is rotatably supported, and the arm part is integrally extended, and a reaction force receiving part for elastically receiving the movement of the arm part is provided. A treading force detecting means is provided by providing a detecting device (potentiometer) for detecting the rotation of the arm portion against the elasticity of the reaction force receiving portion. (See JP-A-7-95744)

[0004] With such a pedal force detecting means,
When the rotation of the crankshaft due to the treading force is transmitted to the resultant shaft, a reaction force applied to the other of the sun gear or the ring gear of the planetary gear mechanism is generated by moving the arm portion against the elasticity of the reaction force receiving portion. The magnitude of the auxiliary power generated by the electric motor of the power unit is detected by detecting the magnitude of the rotation of the gear (rotation angle) and outputting this to the controller as the pedaling force. Is controlled by a controller so as to correspond to the size (pedal force) of the vehicle.

[0005]

In the above-described conventional power unit of a bicycle with an auxiliary power, the pedaling force detecting means is provided so that the treading force detecting means is connected to an arm extending integrally from the other of the sun gear or the ring gear. , A reaction force receiving portion incorporating a spring member, and a rotation angle detecting device (potentiometer) separate from the reaction force receiving portion. However, the structure is complicated, and the assembly to the power unit is troublesome.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a one-way clutch and a one-way clutch for a crankshaft which is rotated by the pedaling force of an occupant. The resultant shaft is coaxially arranged so as to interlock from the planetary gear of the planetary gear mechanism through one of the sun gear or the ring gear, and the other of the rotatably supported sun gear or ring gear of the planetary gear mechanism. On the other hand, means for detecting the treading force by a reaction force acting when the crankshaft and the resultant shaft are interlocked is provided, and an electric motor that outputs auxiliary power according to the treading force detected by the treading force detection means, In a power unit of a bicycle with an auxiliary power which is installed so that the rotation is transmitted to a resultant shaft via a transmission means, the pedaling force detection means may include a sun gear or a ring gear. Against the other to form the arm portions, and is characterized in that it is constituted by providing a load sensor for detecting the strain gauge receives a pressing force of the arm portion.

Further, in the power unit of the bicycle with the auxiliary power as set forth in claim 1, the load sensor is configured such that the load sensor is elastically deformable and is pressed by the arm portion. A member, a strain gauge for detecting deformation of the load receiving member, and an amplifier disposed around the strain gauge are integrally unitized.

Further, in the power unit of the bicycle with the auxiliary power as described in claim 2, as described in claim 3, the load sensor is arranged so that the load sensor is arranged in a direction opposite to the direction of the pressing force of the arm portion. The power unit is attached to the case of the power unit by bolting.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a power unit for a bicycle with auxiliary power according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a bicycle with an auxiliary power to which the power unit of the present invention is applied, that is, an auxiliary driving force by an electric motor is provided according to the magnitude of a force (stepping force) required for a passenger to press a pedal. First, the outline of the main body of the bicycle 1 will be described. First, a head tube is provided at the front end of a down tube 2 that extends obliquely downward from the front of the vehicle body as a main frame of the vehicle body. A handle stem 4 is inserted through the head tube 3 so as to be rotatable about its axis, and a handle bar 5 extending left and right is provided above the handle stem 4. The lower end of the handle stem 4 is connected to an upper end of a front fork 6 which is divided into a pair of left and right sides. Over the left and right lower end Ron FORK 6, the axle of the front wheel 7 is fixed.

A lower end of the seat tube 8 is integrally fixed to a rear end of the down tube 2.
A connecting member 9 made of sheet metal is further integrally fixed over the rear end of the down tube 2 and the lower end of the seat tube 8, and each of a pair of left and right chain stays 10 is attached to the rear of the connecting member 9. A front end is fixed, and a pair of left and right seat stays 11 are provided over the rear end of each of the left and right chain stays 10 and the upper end of the seat tube 8.

At the upper end of the seat tube 8,
A seat pillar 13 to which the saddle 12 is fixed is inserted so as to be vertically adjustable, and an axle of a rear wheel 14 is fixed to the rear ends of the left and right chain stays 10 on both sides thereof. A chain cover 15 for covering an endless chain (both not shown) wound around the drive sprocket on the drive section side and the wheel sprocket on the rear wheel side is installed along the chain stay 10 on one side. ing.

For the main body of such a bicycle 1, a resultant force shaft serving as an output shaft of vehicle driving force, a human force transmitting means for transmitting a passenger's treading force to the resultant force shaft, and a treading force for detecting a treading force and outputting it to a controller A power unit 20 that integrates a detection unit, an electric motor that generates auxiliary power according to the detected treading force, and an auxiliary power transmission unit that transmits auxiliary power by the electric motor to a resultant shaft, has a front side made of resin. In a state covered with the cover 16, the power unit 20 is attached to a lower side of the sheet metal connecting member 9.
The cranks 22 are respectively fixed to the crankshafts 21 protruding to the left and right sides from the case, and pedals 23 are respectively attached to the tips of the left and right cranks 22.

A controller 17 for controlling the current sent to the electric motor based on the detection result from the treading force detecting means is provided behind the power unit 20 and inside the connecting member 9. A battery box 18 containing a battery (not shown) serving as a power source of an electric current to be sent to the electric motor of the power unit 20 is provided above the rear end portion of the down tube 2 and along the front side of the seat tube 8 to the vehicle body. Removably fixed.

FIGS. 2 and 3 show the structure of the power unit 20 itself installed in the bicycle 1 with auxiliary power. In the power unit 20 attached to the connecting member 9 by attachment portions 25 and 26, FIG. An electric motor 30 is installed in a front part thereof in a state integrated with the case 27 of the power unit 20, and a crank in which a hollow resultant force shaft 31 is rotatably and coaxially fitted is provided in a rear part. The shaft 21 is attached to the case 27 of the power unit 20 and a cover 28 that covers the side surface thereof.
31 are installed so as to be freely rotatable.

An idle shaft 33 and a drive shaft 34 are provided between the coaxially arranged crankshaft 21 and resultant shaft 31 and the output shaft 32 of the electric motor 30, respectively. Each shaft 21, 31, 32, 3
Reference numerals 3 and 34 are parallel to each other, and when viewed from the side, a straight line connecting the axes of the respective axes is triangular. 32 are arranged below the line connecting the respective axes.

A small-diameter gear 36 is fixed to an output shaft 32 protruding laterally from the electric motor 30. The gear 36 includes an idle gear 38 rotatably supported by a bearing 37 on an idle shaft 33. Are engaged.

A drive shaft 34 is rotatably supported by a bearing 39 and a bearing 40 with respect to a case 27 and a cover 28 of the power unit 20. The drive shaft 34 has a large-diameter gear meshing with an idle gear 38. 42 is supported via a one-way clutch 41, and a small-diameter gear 43 meshing with the gear 47 of the resultant shaft 31 is formed.

Regarding the crankshaft 21 and the resultant shaft 31,
One side of the crankshaft 21 is rotatably inserted into the hollow portion of the resultant force shaft 31 via the bearing 45 with respect to the hollow resultant force shaft 31 rotatably supported on the case 27 via the bearing 44. The other side of the crankshaft 21 is rotatably supported by a bearing 46 on a cover 28 covering a side surface of the case 27.

In this embodiment, a sun gear 56, which is a part of a planetary gear mechanism 50 described later, is formed integrally with the outer periphery of the inner end of the resultant shaft 31. A large-diameter gear 47 meshing with the small-diameter gear 43 of the shaft 34 is formed integrally, and is formed around the outer end of the resultant shaft 31 protruding outside the case 27.
A drive sprocket 48 is fixed, and an endless chain 49 is stretched over the drive sprocket 48 and a wheel sprocket (not shown) of a rear wheel.

A planetary gear mechanism 50 is provided between the crankshaft 21 and the resultant shaft 31 which are rotatably and coaxially arranged via a one-way clutch 51. The planetary gear mechanism 50 A ring-shaped carrier 52 supported on the crankshaft 21 via a one-way clutch 51, an appropriate number of planetary gears 54 rotatably supported on the carrier 52 by a shaft 53, and rotatable on the crankshaft 21; , And a sun gear 56 formed on the resultant shaft 31. Each planetary gear 54 is located on the ring gear 55 and the sun gear 56 and meshes with both. ing.

The ring gear 55 of the planetary gear mechanism 50 includes a ring gear member 55a having teeth formed thereon for meshing with the planetary gear 54, and a base member 55b rotatably fitted to the crankshaft 21. 55c. In this embodiment, the ring gear 5
As shown in FIG. 2, an arm portion 55d extending downward in an L-shape is formed integrally with the fifth base member 55b as one of the components of the treading force detecting means.

In the vicinity of the rear end of the L-shaped lower portion of the arm portion 55d, a main portion of the treading force detecting means is provided.
The magnitude of the pressing force by the arm 55d is determined by the strain gauge 6
3 is provided with a load sensor 60 for detecting
The arm portion 55d is bolted to the inside of the case 27 so that the lower rear end of the arm portion 55d is always in contact with the front end surface of the load receiving member 62 to which the strain gauge 63 is attached. The movement of 55d (and the entire ring gear 55) is restricted.

As described above, the arm 5 of the ring gear 55
The operation state of the power unit 20 of the present embodiment in which the load sensor 60 is installed for 5d will be described below.

When the occupant steps on the pedal 23, the crankshaft 21
, The rotation of the crankshaft 21 is transmitted from the planetary gear 54 of the planetary gear mechanism 50 via the sun gear 56,
With the speed increased by the planetary gear mechanism 50, the resultant shaft 3
1 and transmitted to the rear wheel 14 by the chain 49 via the resultant shaft 31.

At this time, a reaction force when the rotation of the crankshaft 21 is transmitted to the sun gear 56 of the resultant shaft 31 by the planetary gears 54 acts as a force for rotating the ring gear 55, whereby the ring gear 55 is rotated. The lower rear end of the arm portion 55d extending downward in an L-shape from the load sensor 6
0, the front end face of the load receiving member 62 is pressed, and the pressing force is detected by the strain gauge 63 of the load sensor 60, and the detection result indicates the magnitude of the force required for the occupant to press the pedal 23. The signal is output from the load sensor 60 to the controller 17 as an indicated signal.

When the detection signal of the load sensor 60 is input to the controller 17, the current from the battery contained in the battery box 18 is changed according to the force required for the occupant to press the pedal 23. 17 is controlled by the electric motor 30, that is, when the power is large, the controller 1
7, the current flowing from the controller 17 to the electric motor 30 increases, and if the power is small, the current flowing from the controller 17 to the electric motor 30 decreases, and the power generated by the electric motor 30 is controlled.

The auxiliary power generated by the electric motor 30 under the above-described control is reduced by the large-diameter gear 42 and the one-way clutch 41 from the output shaft 32 of the electric motor 30 via the idle gear 38. The power is transmitted to the drive shaft 34 and further transmitted to the resultant shaft 31 from the small diameter gear 43 of the drive shaft 34 by the large diameter gear 47 of the resultant shaft 31 in a further reduced state. The resultant force with the human power input via the planetary gear mechanism is transmitted from the resultant shaft 31 to the chain 49.
To the rear wheel 14.

That is, the power unit 2 as described above
0, the magnitude of the force required to drive the vehicle by depressing the pedal 23 is detected by the load sensor 60 installed as the pedaling force detecting means, and the controller 17 responds accordingly. By controlling the magnitude of the auxiliary power by the electric motor 30,
An auxiliary driving force corresponding to the burden of human power on the pedal 23 for propulsion driving of the vehicle is provided by the electric motor 30.

By the way, as shown in FIGS. 4 and 5, the structure of the load sensor 60 itself installed in the power unit 20 of the present embodiment is such that mounting bolts are inserted into two upper and lower portions. A front end receiving portion 62a having a cylindrical shape,
A central small-diameter portion 62b having a smaller diameter by one step, and a front end receiving portion 62
The load receiving member 62 integrally formed with the rear end fixing portion 62 c having substantially the same diameter as the load receiving member 6 with respect to the front surface of the substrate 61.
The two rear end fixing portions 62c are fitted together to be integrally connected, and both the substrate 61 and the load receiving member 62 are formed of an elastically deformable metal material such as iron or stainless steel. I have.

In the present embodiment, the front end receiving portion 62a of the load receiving member 62 has a lower rear end surface of the arm portion 55d which comes into contact with the front surface of the front end receiving portion 62a (the front end surface of the load receiving member 62). On the other hand, the front surface of the front end receiving portion 62a is formed as a curved surface protruding in a spherical shape. In this regard, if one of the lower rear end surface of the arm portion 55d and the front end surface of the load receiving member 62 that are in contact with each other is formed as a protruding curved surface, the curved surface is the lower rear end surface of the arm portion 55d. May be on the side.

The load receiving member 62 has a central small diameter portion 62 extending from the rear surface of the front end receiving portion 62a to the front surface of the rear end fixing portion 62c.
a strain gauge member 6 made of a stainless steel plate formed on both sides of b and bent outward and having a strain gauge printed on its outer surface.
3 is provided, and a rear end fixing portion 62 of the load receiving member 62 is provided.
On the front side of c, an amplifier 66 configured by a capacitor, a resistor, or the like, in order to amplify the magnitude of the strain detected from the strain gauge member 63 and output it as a voltage change,
It is installed via a mounting member 64 so as to be connected to the controller 17 by a lead wire 65.

Then, the substrate 61 on which they are installed
A cover member 67 made of a cylindrical resin is fitted to the front surface of the substrate 61 so as to cover the front side of the substrate 61 so that only the front end face side of the front end receiving portion 62a of the load receiving member 62 projects. The cover member 67 and the load receiving member 6 are fixed.
The gap between the front end receiving portions 62a is slidably sealed with silicon or the like.

It should be noted that the load sensor 60 does not output the detected weak signal as it is and amplifies the magnitude of the strain detected from the strain gauge member 63 by the amplifier 66 provided around the load sensor 60. Since the voltage is output as a voltage change after amplification, the noise resistance is good. However, by forming a copper film on the inner surface of the cover member 67, the noise resistance can be further improved.

As described above, the load sensor 60 covered by the cylindrical cover member 67 and integrally formed as a unit is
As shown in FIG. 2, a circular mounting opening formed in the case 27 of the power unit 20 behind the arm 55 d is attached from the rear so as to close the opening with the substrate 61, and then mounted on the substrate. At the mounting hole 61 a of the power unit 20, the case 2 of the power unit 20 is secured by a bolt 58 inserted from the direction opposite to the direction of the pressing force by the arm portion 55 d.
7 will be fixed.

In such a load sensor 60, as described above, the occupant steps on the pedal 23 and presses the crankshaft 21
Receiving the force required to rotationally drive the front end surface of the load receiving member 62 of the load sensor 60 as the pressing force of the lower rear end of the arm portion 55d extending downward from the ring gear 55 in an L-shape. However, as a result, the load receiving member 62 is elastically deformed in response to the pressing force, and the strain of the strain gauge 63 due to the elastic deformation of the load receiving member 62 is detected. Amplifier 6 installed around
6, the voltage of the lead 65
Is output to the controller 17.

As described above, according to the power unit 20 of the present embodiment in which the treading force detecting means is constituted by the arm portion 55d of the ring gear 55 and the load sensor 60, the treading force detecting means includes a spring member. A load sensor 60 having a simple structure does not use a force receiving portion and a rotation angle detecting device separate from the reaction force receiving portion.
Therefore, for the pedaling force detecting means,
The structure can be simplified, the number of components can be significantly reduced, and the power unit 20 can be easily assembled.

That is, since the load sensor 60 is integrally unitized so as to cover the load receiving member 62, the strain gauge 63, the amplifier 66 and the like with the substrate 61 and the cover member 67 as the pedaling force detecting means. Load sensor 60
In the present embodiment, the load sensor 60 can be easily mounted on the case 27 side of the power unit 20 for mounting the power unit 20. Further, in the present embodiment, the bolt 58 inserted from the opposite direction to the direction in which the pressing force by the arm 55d works. Therefore, the load sensor 60 is attached to the case 27 of the power unit 20 with a small number of bolts 58 with sufficient strength against the pressing force.
Is fixed to the case 27.

In this embodiment, one of the rear end face of the lower portion of the arm portion 55d of the ring gear 55 and the front end face of the load receiving member 62 of the load sensor 60 (in this embodiment, the load receiving member 62
Is formed as a protruding curved surface to stabilize the generation of distortion on the load receiving member 62 side due to the contact between the lower rear end surface of the arm portion 55d and the front end surface of the load receiving member 62. Thus, it is possible to improve the accuracy of distortion generation with a simple structure.

Further, in the present embodiment, the load sensor 6
At 0, the strain gauge 63 and the amplifier 66 are integrally unitized, and the magnitude of the strain detected from the strain gauge member 63 is amplified by the amplifier 66 disposed around the strain gauge 63 and then output as a voltage change. Therefore, noise resistance is better than that in which a detected weak signal is output as it is and amplified outside.

Although the embodiment of the power unit of the bicycle with an auxiliary power according to the present invention has been described above, the present invention is not limited only to the above-described embodiment. An output shaft of an electric motor is arranged orthogonally, and an arm is formed on a sun gear side of a planetary gear mechanism (Japanese Patent Laid-Open No. 7-9574).
It is needless to say that the specific structure can be appropriately changed in design, for example, it can be applied to different types of power units.

[0042]

According to the power unit for a bicycle with an auxiliary power of the present invention as described above, the structure of the treading force detecting means can be simplified, the number of parts can be reduced, and the power unit can be reduced. Assembly is also easy.

[Brief description of the drawings]

FIG. 1 is a side view showing the entirety of a bicycle with auxiliary power in which a power unit of the present invention is used.

FIG. 2 is a partial cross-sectional side view showing a state in which a cover on a side surface of a power unit case is removed in one embodiment of the power unit of the present invention installed in the bicycle with auxiliary power shown in FIG.

FIG. 3 is a partial cross-sectional view taken along a line connecting axes of respective shafts of the power unit shown in FIG. 2;

FIG. 4 is a front view showing a load sensor itself assembled as a pedaling force detecting means in the power unit shown in FIG. 2;

FIG. 5 is a sectional view of the load sensor taken along the line AA in FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bicycle with auxiliary power 20 Power unit 21 Crankshaft 27 Case (of power unit) 30 Electric motor 31 Synthetic shaft 50 Planetary gear mechanism 51 One-way clutch 54 Planetary gear 55 Ring gear 55d Arm part (pedal force detecting means) 56 Sun gear 58 Bolt (load sensor) (For mounting) 60 Load sensor (pedal force detecting means) 63 Strain gauge member

Claims (3)

[Claims] 1. A resultant force shaft is coaxially arranged with respect to a crankshaft rotated by a stepping force of an occupant through a one-way clutch and a planetary gear of a planetary gear mechanism through one of a sun gear and a ring gear. Further, a means for detecting a treading force by a reaction force acting when the crankshaft and the resultant shaft are interlocked is provided for the other of the sun gear or the ring gear rotatably supported by the planetary gear mechanism. An electric motor that outputs auxiliary power in accordance with the treading force detected by the treading force detecting means is installed in a power unit of an auxiliary powered bicycle in which the rotation is transmitted to a resultant shaft via a transmitting means. Means for receiving a pressing force of the arm portion formed on the other of the sun gear and the ring gear and detecting the load by a strain gauge; A power unit for a bicycle with auxiliary power, comprising a weight sensor. 2. A load sensor comprising an elastically deformable load receiving member pressed by an arm portion, a strain gauge for detecting deformation of the load receiving member, and an amplifier disposed around the strain gauge. The power unit for an auxiliary power-assisted bicycle according to claim 1, wherein the power unit is a unit. 3. The auxiliary power unit according to claim 2, wherein the load sensor is attached to the case of the power unit by bolting in a direction opposite to the direction of the pressing force of the arm unit. Bicycle power unit.