JP2002116099A - Stepping force detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate assembly and improve strength by simplifying the structure of a stepping force sensor. SOLUTION: Part of a stepping force which rotates a crankshaft 36 by a helical drive gear 36H and a helical driven gear (slider) 43 is separated into the component of force in the axial direction of the crankshaft. The slider 43 id deflected by the divided component of force and presses a load detecting part 40 via a thrust bearing 45. The load detecting part 40 is formed of a resin dielectric and two opposed electrodes sandwiching the resin dielectric. The dielectric is compressed according to the deflecting force (representing the stepping force) of the slider 43 to change the distance between the electrodes. The distance between the electrodes is processed at a detecting circuit to detect the stepping force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary torque applied to a handle rim of a wheelchair by hand, and a pedaling force applied to a pedal of a bicycle, a pedal boat or the like (hereinafter referred to as "pedaling force"). The present invention relates to a tread force detection device for detecting a tread force, and more particularly to a tread force detection device that detects the magnitude of a tread force based on a capacitance that changes according to an applied tread force.

[0002]

2. Description of the Related Art A pedaling force detecting device for detecting a pedaling force as a change in capacitance has been known. For example, JP-A-2000-1
Japanese Patent No. 18476 discloses an apparatus configured to transmit a treading force input from a treading force inputting means to a driving force inputting means connected to a driving wheel via an elastic member. A tread force detection device that outputs a tread force value corresponding to the relative rotation amount based on a capacitance that changes in response to the relative rotation amount is described.

[0003] The variable capacitance sensor described in the publication has a structure in which a first electrode and a second electrode deposited on the surface of an insulating film are laminated on each other and are wound in a roll shape. Pressure is applied in the radial direction according to the relative rotation amount of each of the input means.

[0004]

In the above-described conventional treading force detecting device, since the electrode of the variable capacitance sensor is pressurized by the treading force, a mechanical property that can withstand a large pressing force is required. The structure is complicated. Further, since the electrode is deposited on the insulating film, it is not easy to improve strength and durability. As described above, in the conventional sensor, there are great restrictions in selecting the material of the structure and the parts.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a pedaling force detecting device having a structure capable of obtaining high durability.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a force-dividing means for partially applying a portion of a pedaling force for rotating a drive shaft in the axial direction of the drive shaft; The first feature is that a capacitance sensor is provided in which the component force is applied and the capacitance changes according to the magnitude of the component force. Further, according to the present invention, the component force means includes a helical drive gear and a helical driven gear rotated by a treading force, and any one of the helical drive gear and the helical driven gear can be biased in the axial direction of the drive shaft. A second feature of the present invention is that the capacitance sensor is arranged so that the distance between the electrodes changes according to the biasing force of the bias.

Further, the present invention comprises a thrust bearing for receiving an urging force due to a bias of any one of the helical drive gear and the helical driven gear, wherein the capacitance sensor has an elastic dielectric, A third feature lies in that it is constituted by electrodes arranged so as to sandwich the body, and the biasing force is applied to one of the electrodes via the thrust bearing.

Further, the present invention has a fourth feature in that the dielectric comprises a sheet-shaped adhesive resin material or a plurality of resin spherical bodies and an adhesive filling the space between the resin spherical bodies.
Further, the present invention has a fifth feature in that the capacitance sensor and the electrode are made common, and a reference capacitance sensor arranged adjacent to the capacitance sensor is provided.

According to the first to fifth features, a part of the treading force is divided and acts to change the distance between the electrodes of the capacitance sensor. According to a second characteristic, in particular, said component force is generated by the helix angle of the helical gear. Third
According to the characteristics of the thrust generated by the helical gear,
It acts on the dielectric having elasticity via the thrust bearing, and the distance between the electrodes sandwiching the dielectric changes to change the capacitance.

According to the fourth feature, the dielectric is adhered and fixed to the electrodes on both sides by its adhesiveness. According to the fifth feature, it is possible to reduce the influence of environmental temperature and disturbance.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a side view of an electric assisted bicycle having a pedaling force detection device according to the present invention, and FIG. 2 is a cross-sectional view taken along a line including the crankshaft of FIG. In FIG. 1, a body frame 21A of the electric assisted bicycle includes a head pipe 22 at a front end thereof,
Down pipe 23 extending backward from head pipe 22
And a support pipe 24 fixed to the rear end of the down pipe 23 and extending in the left-right direction of the vehicle body, and a seat post 25 rising upward from the support pipe 24.

The head pipe 22 has a front fork 2
6 is rotatably supported. Front fork 26
A front wheel WF is pivotally supported at a lower end of the front fork 26. The front wheel WF is steerable by a handle 27 provided at an upper end of a front fork 26. At the rear ends of a pair of left and right rear forks 28 extending rearward from the seat post 25, a rear wheel WR as a drive wheel disposed between the pair of rear forks 28 is supported. A pair of left and right stays 29 is provided between an upper portion of the seat post 25 and both rear forks 28.

The seat post 25 has a support shaft 3 having an upper end with the seat 30 so that the height of the seat 30 can be adjusted.
1 is attached. The seat post 25 below the seat 30
A battery storage box 32 for detachably storing a battery is provided at the front of the battery pack.

On the vehicle rear side of the support pipe 24,
A power unit 35 having an electric motor 34 supplied with electric power from a battery stored in the battery storage box 32 is arranged. The power unit 35 is supported by the support pipe 24 and the right rear fork 28.

A chain 71 extends between a driving sprocket 48 driven by the crankshaft 36 and a driven sprocket 70 connected to the rear wheel WR. The rotation of the driving sprocket 48 is transmitted to the driven sprocket 70 by the chain 71, and the rear wheel WR is driven. The chain 71 is also applied to the output sprocket 69 of the power unit 35 between the driving sprocket 48 and the driven sprocket 70, and the output of the power unit 35, that is, the driving force of the electric motor 34 is applied to the pedals 37R, 37.
It is added to the pedaling force input from 7L. Electric motor 34
The output is controlled according to the magnitude of the pedaling force. For controlling the electric motor 34 according to the treading force, a treading force detection device described in detail later is provided. The tension of the chain 71 can be adjusted by an idle sprocket 73 mounted on an arm extending from the casing 75.

In FIG. 2, ball bearings 39L and 39R are provided at both ends of a support pipe 24 provided on the body frame 21A.
9L, 39R, the crankshaft 36 as a drive shaft
Is supported. Crank pedals 37L, 37R are connected to the left end and the right end of the crankshaft 36, respectively, and fixed with nuts 54, 55, respectively. The housing of the ball bearing 39L is supported by being screwed to the end of the support pipe 24. The ball bearing 39R is
6 is supported by being screwed onto the outer periphery of the end of the support pipe 24.

At the right end of the support pipe 24, a load detector 40 functioning as a treading force sensor and a sensor case 42 accommodating a circuit board 41 are fixed. Near the right end of the crankshaft 36, the inside of the crank pedal 37R (vehicle center side)
A helical spline 36H is formed adjacent to the helical spline 36H.
3 are provided. The slider 43 has a spline connected to the helical spline 36H, and rotates with the helical spline 36H. Further, a driving sprocket 48 is supported on the outer periphery of the slider 43 via a one-way clutch 44 including a ratchet mechanism.

When the crank pedals 37L and 37R are depressed, the slider 43 moves the crankshaft 3 by the force acting to prevent the rotation of the driving sprocket 48, that is, the pedaling force.
The direction of the helical spline 36H is set so as to receive a thrust biasing the load detector 40 in the axial direction of No. 6. A thrust bearing 45 is provided between the helical spline 36H and the load detector 40,
The thrust received by 3 is transmitted to the load detection unit 40 from the helical spline 36H via the thrust bear rig 45. Between the slider 43 and the crank pedal 37R,
A cover 46 that covers the slider 43, the one-way clutch 44, and the hub of the sprocket 48 is put on.

FIG. 3 is an enlarged sectional view showing a main part of a tread force sensor including a load detecting section 40, a circuit board 41 and the like, and FIG. 4 is an exploded perspective view of the same. Boss part 4 formed in sensor case 42
The crankshaft 36 passes through the center hole of 2A. A first electrode 57 is formed on the circuit board 41 fixed to the sensor case 42, and a dielectric 58 is disposed on the first electrode 57. Further, the dielectric 58 has the second electrode 59 and the third
Electrodes 60 are arranged adjacently. Dielectric 58, second electrode 59
Each of the third electrode 60 and the third electrode 60 is formed in an annular shape, and is arranged coaxially with the center hole of the boss 42A. The inner diameter of the third electrode 60 is set to be larger than the outer diameter of the second electrode 59 so that the third electrode 60 is located on the outer periphery of the second electrode 59. The dielectric 58 has one surface adhered to the first electrode 57 and the other surface adhered to the second electrode 59. The dielectric 58 is made of an elastic material such as a resin, and preferably has adhesiveness itself.

The second electrode 59 and the third electrode 60 are connected to the printed wiring circuits 59B and 60B of the circuit board 41 through the lead portions 59A and 60A. A circuit element (not shown) is mounted on the circuit board 41. A thrust bearing 45 that transmits the thrust of the slider 43 due to the treading force to the third electrode 60 is disposed adjacent to the third electrode 60.

With the above configuration, a first capacitor and a second capacitor are formed between the first electrode 57 and the second electrode 59 and the third electrode 60, respectively. FIG. 5 is a diagram showing an equivalent circuit of the first and second capacitors. The capacitance of the first capacitor CA formed by the first electrode 57 and the second electrode 59 changes according to the pedaling force. That is, when the thrust of the slider 43 due to the treading force is applied to the second electrode 59, the dielectric 58 is compressed according to the thrust, that is, the treading force that generates the thrust. As a result, the distance between the first electrode 57 and the second electrode 59 decreases, and the capacitance increases.

On the other hand, since the third electrode 60 does not contact the thrust bearing 45, the third electrode 6 is
The dielectric between the zero and the first electrode 57 is not compressed. Therefore, the capacitance of the second capacitor CB formed by the first electrode 57 and the third electrode 60 does not change due to the pedaling force. The second capacitor CB functions as a reference capacitor for accurately detecting a change in capacitance of the first capacitor by canceling disturbance due to environmental temperature, stray capacitance, and the like.

FIG. 6 shows the first and second capacitors C
FIG. 3 is a diagram illustrating a pedaling force detection circuit including A and CB. In the figure, a first oscillator including a first capacitor (hereinafter, referred to as “detection capacitor”) CA, a resistor R3, and a comparator IC2, a second capacitor (hereinafter, referred to as “reference capacitor”) CB, a resistor R4, and a comparator IC
And a second oscillator including the first oscillator.

Comparator IC1 and comparator I
The comparison terminal (plus terminal) of C2 has a reference capacitor C
B and the potential of the detection capacitor CA are supplied. The reference potential REF of the comparators IC1, IC2 is determined by the resistors R5, R6, R7. The output of the comparator IC2 is input to a time constant circuit including a resistor R0 and a capacitor C0 via an inverting circuit N3. The potential between the resistor R0 and the capacitor C0 is input to the amplifier circuit AMP and amplified. The output of the amplifier circuit AMP is input to an A / D converter input terminal of the CPU 61. The potential of the inverting input terminal of the operational amplifier IC3 included in the amplifier circuit AMP is supplied from the CPU 61 via the D / A converter 62.

The reference potential terminal of the comparator IC1
Reference potential REF-L generated by resistors R5, R6, and R7
, REF-H are input. The respective reference potentials are set in the following relationship. “Reference potential REF-L <REF-H”. The output of the comparator IC1 is input to the inverting circuit N1,
The output of 1 is an inverting circuit N2 and resistors R7, R4, R3.
Is input to The resistors R1 and R are connected to the output side of the inverting circuit N2.
2 are connected in series. The potential between the resistors R1 and R2 is determined by the transistor Tr connected to the detection capacitor CA.
Connected to the base.

The operation of the pedaling force detection circuit having the above configuration will be described with reference to the waveform diagram of FIG. In FIG.
Is the potential of the reference capacitor CB (potential at point A in FIG. 6) Ecb
, Waveform B is the output waveform of the inverting circuit N1 (potential at point B in FIG. 6), waveform C is the potential of the detection capacitor CA when the capacitance is small (potential at point C in FIG. 6) Eca, and waveform C ′ is The potential Eca of the detection capacitor CA when the capacitance is large (potential at point C in FIG. 6) Eca, the waveform D is the output waveform of the inverting circuit N3 when the capacitance is small, and the waveform D 'is when the capacitance is large. Output waveforms of the inverting circuit N3 of FIG.

When the output of the comparator IC1 is "low", the reference potential terminal of the comparator IC1 has a reference potential RE.
FH is input, and the potential Ecb at the point A rises according to a time constant determined by the resistor R4 and the reference capacitor CB. Potential Ecb
Is higher than the reference potential REF-H, the output of the inverting circuit N1 is at the high level. When the potential Ecb exceeds the reference potential REF-H, the potential supplied to the reference potential terminal of the comparator IC1 becomes the reference potential REF-L, and the reference capacitor CB is discharged. When the voltage is switched to the reference potential REF-L and the reference capacitor CB starts discharging, the output of the inverting circuit N1 immediately changes to the low level.

While the output of the inverting circuit N1 is at the high level,
The potential Eca of the detection capacitor CA also increases. This rising speed increases as the capacitance of the detection capacitor CA decreases (see waveforms C and C ′). The potential Eca is equal to the reference potential REF-
When it exceeds H, the output of the comparator IC2 changes to high level, and the output of the inverting circuit N3 changes to low level (see waveforms D and D '). However, the output of the inverting circuit N1 is maintained at a high level until the potential Ecb of the reference capacitor CB exceeds the reference potential REF-H.
Is still rising (see waveforms C and C ').

The potential Ecb of the reference capacitor CB is equal to the reference potential.
When the voltage exceeds REF-H, the output of the inverting circuit N1 changes to low level, while the output of the inverting circuit N2 changes to high level. When the inverting circuit N2 changes to a high level,
The transistor Tr is turned on, and the potential Eca of the detection capacitor CA drops sharply and discharges (waveforms C and C ′).
reference). As a result, the output of the comparator IC2 rapidly changes to a low level, and the output of the inversion circuit N3 changes to a high level (see waveforms D and D ').

As described above, the capacitance of the detection capacitor CA, which represents the magnitude of the pedaling force, decreases as the pedaling force increases. Accordingly, the high-level period of the output of the comparator IC2 becomes shorter (the on-duty becomes smaller), and the on-duty of the output of the inverting circuit N3 becomes larger.

The output of the inverting circuit N3 is a time constant circuit comprising an output resistor R0 and a capacitor C0. The output is smoothed in accordance with the time constant and input to the A / D converter input terminal of the CPU 61. Even with the same time constant, the higher the on-duty of the output of the inverting circuit N3, the higher the potential input to the A / D converter input terminal. Therefore, based on this potential, the CPU 61 determines the magnitude of the pedaling force and determines a control signal to be supplied to the electric motor 34.

By using the reference capacitor CB whose capacitance does not change depending on the magnitude of the pedaling force, for example, even if the temperature of the environment changes, the capacitances of the detection capacitor CA and the reference capacitor CB both change. Only when the frequencies of the outputs Eca and Ecb change, the inverting circuit N3
Does not affect the on-duty of the output, i.e., the potential of the capacitor C0.

Next, a modification of the tread force sensor will be described. FIG. 8 is an enlarged cross-sectional view showing a main part of a tread force sensor including a load detection unit 40, a circuit board 41, and the like according to a modification. FIG. 9 is an exploded perspective view, and the same reference numerals as in FIGS. Indicates equivalent parts. Unlike the first electrode 57, the first electrode 571 formed on the circuit board 41 is not a perfect ring but a horseshoe having an intermittent portion. Then, printed wirings 591B and 601B are formed so as to be located at the intermittent portions. The second electrode 591 and the third electrode 601 are arranged adjacent to the dielectric 581 arranged on the first electrode 571. The dielectric 581 includes a second electrode 591 and a printed wiring 59.
1B, and a lead 601A connecting the third electrode 601 and the printed wiring 601B.
Is buried. Both the lead portions 591B and 601B are made of conductive rubber, and both ends of the lead 58 are exposed on both surfaces.

With the above configuration, a detection capacitor and a reference capacitor are formed between the first electrode 571, the second electrode 591 and the third electrode 601 respectively. First electrode 571 and second electrode 591, first electrode 571 and third electrode 6
Since 01 is electrically connected via the lead portions 591B and 601B, it can be applied to the circuit of FIG. 6 in the same manner as the tread force sensor of FIG. 3 to detect the tread force. Since the lead portion can be shortened, a detection error due to stray capacitance can be reduced.

Although the above-described dielectric material is a sheet-like adhesive resin, the present invention is not limited to such a sheet-like material, and may be, for example, as follows. FIG. 10 is a sectional view showing a modification of the dielectric. In the figure, a large number of resin spherical bodies 581 are arranged between a first electrode 57 and a second electrode 59 formed on a circuit board 41, and an adhesive 582 is filled between the spherical bodies 581. Have been. Spherical body 581 and adhesive 582
Act as a dielectric. The diameter of the spherical body 581 is 10
It is better to select between ５００500 μm. In addition, spherical body 5
It is preferable to apply a mixture of the material 81 and the adhesive 582 in advance on the first electrode 57. According to the dielectric made of the spherical body 581 and the adhesive 582, it is relatively easy to change the characteristics of the sensor as desired by selecting the respective materials and volume ratios.

The present invention is not limited to the above embodiment,
Various modifications can be made. For example, the axial movement of the helical gear 36H on the driving side is fixed, and the slider 43 is configured to be able to be biased in the axial direction. However, the relationship may be reversed. That is, the axial movement of the driven side of the helical gears on the driving side and the driven side may be fixed, and the driving side may be biased. Crankshaft 36 and helical gear 36H
And the helical gear 36H can be slid in the axial direction with respect to the crankshaft 36, and the axial movement of the helical gear 36H is transmitted to the load detecting portion of the capacitance sensor via a thrust bearing. Can be configured.

[0037]

As described above, according to the first to sixth aspects of the present invention, the capacitance of the tread force sensor can be changed by applying a part of the tread force in the axial direction of the drive shaft. In particular, according to the second aspect of the present invention, the thrust generated by the rotation of the helical gear can be applied to the tread force sensor, so that the structure is simple.

According to the third aspect of the present invention, since the thrust can be received by the elastic dielectric, the compression and compression of the elastic body can be prevented.
By the extension operation, the distance between the capacitor electrodes can be easily changed according to the magnitude of the thrust. According to the fourth and fifth aspects of the present invention, the electrodes can be easily arranged at desired intervals by the adhesive force of the dielectric. Therefore, the assembling work can be simplified, and the strength can be increased due to the simple structure. According to the sixth aspect of the present invention, the influence of environmental temperature and disturbance can be reduced, and by using a common electrode, the distance between the electrodes can be easily equalized in the two capacitance sensors.

[Brief description of the drawings]

FIG. 1 is a side view of an electric assisted bicycle including a pedaling force detection device according to the present invention.

FIG. 2 is a sectional view taken on a line including the crankshaft of FIG. 1;

FIG. 3 is an enlarged cross-sectional view of a tread force sensor.

FIG. 4 is an exploded perspective view of the tread force sensor.

FIG. 5 is an equivalent circuit diagram of a main part of a tread force sensor.

FIG. 6 is a tread force detection circuit diagram.

FIG. 7 is a signal waveform diagram in the pedaling force detection circuit.

FIG. 8 is an enlarged sectional view of a pedaling force sensor according to a modification.

FIG. 9 is an exploded perspective view of a tread force sensor according to a modification.

FIG. 10 is an enlarged sectional view of a main part according to a modified example of a dielectric.

[Explanation of symbols]

24 ... support pipe, 36 ... crankshaft, 37L, 37
R: crank pedal, 40: load detector, 41: circuit board, 42: sensor case, 43: slider, 4
4 one-way clutch, 45 thrust bearing, 48 drive sprocket, 57 first electrode,
58: dielectric, 59: second electrode, 60: third electrode

Claims (6)

[Claims] 1. A component force means for componentizing a part of a tread force for rotating a drive shaft in the axial direction of the drive shaft, wherein the component force in the axial direction is applied, and static force is applied according to the magnitude of the component force. A pedaling force detection device, comprising: a capacitance sensor whose electric capacity changes. 2. The helical drive gear and the helical driven gear that are rotated by a treading force, wherein one of the helical drive gear and the helical driven gear can be biased in the axial direction of the drive shaft. The pedaling force detecting device according to claim 1, wherein the capacitance sensor is arranged such that a distance between the electrodes changes according to a biasing force due to the bias. A thrust bearing for receiving an urging force due to a bias of one of the helical drive gear and the helical driven gear, wherein the capacitance sensor comprises: a dielectric material having elasticity; The treading force detecting device according to claim 2, comprising an electrode disposed, wherein the urging force acts on one of the electrodes via the thrust bearing. 4. The pedaling force detecting device according to claim 3, wherein the dielectric is a sheet-like adhesive resin material. 5. The pedaling force detecting device according to claim 3, wherein the dielectric comprises a plurality of resin spherical bodies and an adhesive filling between the resin spherical bodies. 6. An electrode common to the capacitance sensor and an electrode,
The treading force detecting device according to any one of claims 1 to 5, further comprising a reference capacitance sensor disposed adjacent to the capacitance sensor.