JP3953210B2 - Torque detection device for electric bicycle - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a torque detection device for an electric bicycle, and in particular, for example, a battery and an electric motor mounted on a bicycle, detects a pedaling force torque of a passenger, and adds a driving force of the electric motor to detect the torque of the electric bicycle. Relates to the device.
[0002]
[Prior art]
Recently, an electric bicycle that has a battery and an electric motor mounted on the bicycle and appropriately adds auxiliary power of the electric motor to the human power (stepping force) of a passenger has been put into practical use.
This electric bicycle is configured to generate auxiliary power of the electric motor in accordance with the magnitude of the pedaling force torque generated by the passenger, and is equipped with a torque detection device for detecting the pedaling force torque for that purpose. For example, as disclosed in JP-A-4-100790 [B62M23 / 02], a human driving force is applied to a torsion bar, and the magnitude of the torsion is detected by a potentiometer (rotation angle detector). Alternatively, a method of detecting with a strain gauge attached to a torsion bar is known. Further, as disclosed in JP-A-4-244496 [B60L15 / 20], there is also known a system for detecting the tension of a chain.
[0003]
[Problems to be solved by the invention]
In the conventional method in which the torsion angle of the torsion bar as described above is used to detect the human driving force with a potentiometer or strain gauge, the potentiometer or strain gauge is attached to the rotating torsion bar. In order to transmit from the vehicle body side (fixed side) to the vehicle body, a mechanism for transmitting the displacement to the fixed portion is required, the structure is complicated and expensive, and there is a problem in reliability and durability due to deterioration due to wear.
[0004]
In addition, the method of detecting the chain tension is dangerous because there are many exposed portions and the chain tension can be easily changed from the outside.
SUMMARY OF THE INVENTION Therefore, a main object of the present invention is to provide a torque detector for an electric bicycle that has a simple structure, is less likely to be damaged or deteriorated, can be reduced in size, and has excellent rigidity.
[0005]
[Means for Solving the Problems]
The present invention relates to an electric bicycle in which a battery and an electric motor are mounted on a bicycle and the driving force of the electric motor is added to the rider's stepping force, and a crank member that is rotated by a pedal, and a ring-shaped sensor having a sensor housing portion. A drive gear wheel (36) rotatably held between the crank member and the sensor case member; a torque sensor housed in the sensor housing portion and having a pressure receiving member (92); The wheel is formed with a central opening (36a) into which the ring-shaped sensor case member can be fitted, and a groove (96) in communication with the central opening for disposing the sensor storage portion. parts, said provided between the one end and the other end of the groove, the pressure receiving member is pressed by one end of the groove, electrostatic A torque detection device of the bicycle.
[0006]
[Action]
A drive gear wheel is rotatably clamped and fixed by a crank member rotated by a pedal and a ring-shaped sensor case member having a sensor housing portion, and formed on the pressure receiving member of a torque sensor housed in the sensor housing portion. Torque associated with the rotational force of the pedal is applied by the pressed means.
[0007]
【The invention's effect】
According to the present invention, the torque sensor for detecting the pedaling force torque of the occupant can be incorporated in the crank rotating portion, so that a small and high performance torque detecting device is provided with a simple mechanism. Further, the torque sensor can be easily inserted into the sensor storage portion from the side surface, and the detection device can be easily assembled.
[0008]
【Example】
An embodiment of the present invention will be described with reference to FIGS.
First, FIG. 1 shows an electric bicycle 12 equipped with a torque detection device 10, which has a front wheel 16 and a handle 18 at the front of a main body frame 14, and a rear wheel 20 at the rear of the main body frame 14. Yes.
[0009]
In addition, a seat tube 24 having a saddle 22 at the upper end is disposed at a substantially central portion of the main body frame 14, and a bottom bracket 28 pivotally supporting a pedal mechanism 26 is disposed at the lower end of the seat tube 24 as shown in FIG. Has been.
The pedal mechanism 26 includes a crankshaft 30 pivotally supported by the bottom bracket 28, crank arms 32 and 32 fixed to both ends of the crankshaft 30, and pedals 34 and 34 pivotally supported at the respective distal ends of the crankarm 32. And a drive gear wheel 36 made of a sprocket fitted on the right side of the crankshaft 30 so as to be relatively rotatable.
[0010]
Further, an endless chain 42 is stretched between a driven gear wheel (not shown) made of a sprocket fitted to the axle 40 of the rear wheel 20 and the drive gear wheel 36, The driving force by human power is transmitted. The rear wheel 20 has a diameter that is 2/3 smaller than the diameter of the front wheel 16, thereby improving the design and reducing the size and weight.
[0011]
An auxiliary power unit 46 that assists a driving force by human power in a frame portion 44 located between the seat tube 24 and the rear wheel 20 is attached to the main body frame 14 via a mounting substrate 48. The auxiliary power unit 46 includes a DC electric motor 50 as an auxiliary power source and a battery 52 as a power source of the motor, and a motor pulley 56 is fixed to the output shaft 54 of the motor 50. A belt-like transmission that directly transmits auxiliary power of the DC electric motor 50 to the rear wheel 20 between the motor pulley 56 and a driven pulley 60 as a rotating body integrally formed with the same diameter on the left side of the rim 58 of the rear wheel 20. A belt 62 is stretched.
[0012]
The rotational speed of the DC electric motor 50 is reduced on the rear wheel due to the relationship between the diameter of the motor pulley 56 fixed to the motor output shaft 54 and the diameter of the driven pulley 60 integrally formed with the rim 58 of the rear wheel 20. Communicated. The reduction ratio is appropriately set within a range of 1/10 to 1/20, but a reduction ratio of 1/10 is desirable. In this case, at the maximum output of the DC electric motor 50, the assist traveling speed of the electric bicycle is 24 km / h.
[0013]
For example, when the radius of the motor pulley 56 is rcm and the radius of the driven pulley 60 is 10 rcm, the reduction ratio is 2πr / 20πr = 1/10, and the rotational speed of the DC electric motor 50 is reduced to 1/10 and the rear wheel 20 Is transmitted to.
Further, in order to adjust the tension of the belt-like transmission belt 62, an automatic tension adjusting device 68 having a rotating roller 64 that contacts the belt and a coil spring 66 that presses and biases the roller against the belt is mounted on the mounting substrate 48. .
[0014]
The output of the DC electric motor 50 is controlled by a control unit (not shown) including a microcomputer based on a torque signal from the torque detection device 10 described below. That is, the torque sensor that constitutes the torque detection device 10 has, for example, a cylindrical magnetostrictive element 10a using a magnetostrictive material whose magnetization changes by applying a pedaling force torque, and an inductance caused by a change in magnetization of the magnetostrictive element 10a. A magnetostrictive sensor composed of a changing magnetostriction detection coil 10b is desirable.
[0015]
Next, the torque detector 10 will be described with reference to FIGS.
The crank rotation unit 70 in which the torque detection device 10 is arranged includes a crankshaft 30 that is pivotally supported by a cylindrical crank bearing 72 that is inserted through the bottom bracket 28, and a hanger ring 73 at a wheel side end of the crank bearing 72. A ring-like shape in which a disc-like slip ring portion 74 to be locked, a disc-like mounting plate 76 fixed to the base end of the right crank arm 32, and a sensor storage portion 78 opening three sides are integrally formed. Sensor case member 80, the drive gear wheel 36 and the rotation side slip ring portion 82.
[0016]
The rotation-side slip ring portion 82 is interposed between the disc-shaped mounting plate 76 and the ring-shaped sensor case member 80, and the center of the drive gear wheel 36 is placed on the ring-shaped step portion 80 a formed on the sensor case member 80. The drive gear wheel 36 is rotatably clamped between the sensor case member 80 and the mounting plate 76 using a fastener such as a screw. Further, the coil spring 38 is inserted into the crankshaft 30, and the fixed-side slip ring portion 74 is pressed against the rotation-side slip ring portion 82 by the coil spring 38 to maintain the contact state. Further, a ring-shaped sponge member 84 is disposed between the fixed-side slip ring portion 74 and the rotation-side slip ring portion 82 to prevent dust and water from entering from the outside, and the base end portion of the crank arm 32 is attached to the nut. It is fixed to the crankshaft 30 by using a stopper 86 such as the above.
[0017]
On the other hand, the sensor accommodating portion 78 formed in the sensor case member 80, inserted magnetostrictive element 10a in the bobbin 88 wound with a sensing coil 10b as shown in FIG. 7 is housed laterally through the pressure receiving plate 90 Further, a spherical pressure receiving member 92 is provided on the tip surface of the magnetostrictive element 10a, and the sensor housing 78 is closed by the case lid 94 so that the spherical portion of the pressure receiving member 92 is exposed. Further, by sticking a Teflon (registered trademark) sheet on both surfaces of the magnetostrictive element 10a, the unevenness of the material can be absorbed and pressure can be uniformly received over the entire surface. If the sensor case member 80 and the case lid 94 are made of a magnetic material, accurate torque detection can be performed.
[0018]
Further, the drive gear wheel 36 that is rotatably held between the mounting plate 76 fixed to the crank arm 32 and the ring-shaped sensor case member 80 is formed with a horizontally long groove portion 96 in which the sensor storage portion 78 is disposed. ing. The groove portion 96 communicates with the central opening 36a of the drive gear wheel 36, and one end edge 96a of the groove portion 96 is applied to the magnetostrictive element 10a via the spherical pressure receiving member 92 housed in the sensor housing portion 78. In other words, the pedaling force torque transmitted from the pedal 34 via the crank arm 32 by the passenger's human power is received. A notch 98 corresponding to the mounting plate 76 of the crank arm 32 facing the groove 96 is also formed. Further, a U-shaped leaf spring 100 is disposed in the sensor housing portion 78 facing the other end edge 96 b of the horizontally long groove portion 96 so that the pressure receiving member 92 always abuts against the one end edge 96 a of the groove portion 96.
[0019]
Then, a change in magnetization occurs in the magnetostrictive element 10a due to fluctuations in the pedaling torque, and the inductance of the magnetostrictive detection coil 10b changes due to this change in magnetization. This inductance change is converted into an electrical signal by the magnetostriction detection coil 10b and processed by a control unit including a microcomputer. On the basis of the processing result, the auxiliary power of the DC electric motor 50 is adjusted and added to the pedaling force torque by human power, so that the assist traveling can be performed.
[Brief description of the drawings]
FIG. 1 is an illustrative view showing an overall configuration of an electric bicycle according to an embodiment of the present invention.
FIG. 2 is an enlarged perspective view of a main part in FIG.
FIG. 3 is a plan view of a main part when the crank rotation part in FIG. 2 is viewed from the right side;
4 is a cross-sectional view taken along arrow AA in FIG. 3;
FIG. 5 is a perspective view of a principal part showing an assembled state of a crank rotating part in one embodiment of the present invention.
6 is a plan view of relevant parts showing an assembled state of the crank rotation part in FIG. 5. FIG.
7 is a cross-sectional view taken along the line BB in FIG.
FIG. 8 is an exploded perspective view of the crank rotation unit shown in FIG. 5;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Torque detection apparatus 10a ... Magnetostrictive element 10b ... Magnetostriction detection coil 12 ... Electric bicycle 14 ... Main body frame 30 ... Crankshaft 32 ... Crank arm 36 ... Drive gear wheel 36a ... Center opening 50 ... DC electric motor 70 ... Crank rotation part 72 ... Crank bearing 76 ... Mounting plate 78 ... Sensor housing part 80 ... Sensor case member 92 ... Pressure receiving member 94 ... Case lid 96 ... Horizontally long groove part 96a ... One end edge

Claims (2)

In an electric bicycle that runs with a battery and an electric motor mounted on the bicycle and the driving force of the electric motor is added to the pedaling force of the passenger,
A crank member rotated by a pedal,
A ring-shaped sensor case member having a sensor housing,
A drive gear wheel rotatably clamped and fixed by the crank member and the sensor case member;
A torque sensor housed in the sensor housing section and having a pressure receiving member,
The drive gear wheel is formed with a central opening (36a) into which the ring-shaped sensor case member can be fitted, and a groove (96) in communication with the central opening and in which the sensor housing portion is disposed.
The sensor storage portion is provided between one end and the other end of the groove portion,
The torque detection device for an electric bicycle, wherein the pressure receiving member is pressed by one end of the groove . The torque detection device for an electric bicycle according to claim 1 , wherein the torque sensor includes a magnetostrictive element that causes a change in magnetization due to a pressure applied to the pressure receiving member, and a magnetostriction detection coil that changes an inductance due to a change in magnetization of the magnetostrictive element. .

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