JPH11248559A - Torque detecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a torque detecting apparatus whose structure is simple, whose strength is high and which can be made small and lightweight, by a method wherein a reaction force is taken out as a change in an inductance by making use of a change in the magnetic characteristic of a magnetic body which directly receives the reaction force of a drive part generated by a torque. SOLUTION: When a shaft 21 is turned and driven at a prescribed speed in a planet gear mechanism 20, a reaction force P which is proportional to the magnitude of a torque transmitted form the shaft 21 to a ring gear 23 is generated. Since the reaction force P is received by a magnetic body 2 in a detector 1 via a shock absorbing material 5, a reactive force P acts on the magnetic body 2 in its axial direction. On the basis of a charge in an inductance generated due to a reduction in the permeability of the magnetic body 2 by its magnetostrictive effect, a voltage V across both ends of a detecting coil 3 is changed in proportion to its trun ratio. A signal processing circuit amplifies the voltage V as an output signal. On the basis of the output signal, a CPU computes the magnitude of the torque transmitted from the shaft 21. As a result, it is possible to obtain a torque detecting apparatus whose structure is simplified, whose strength is high and which can be made small and lightweight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque detecting device for electromagnetically detecting a torque by extracting a change in magnetic properties of a magnetic body or the like directly receiving a load of a driving section caused by the torque as a change in coil inductance.

[0002]

2. Description of the Related Art Potentiometers have been conventionally known as means for detecting rotational torque. This potentiometer detects a torque by converting a displacement of a drive unit due to a load generated by a rotational torque into a change in electric resistance, and detecting a change in current (voltage) caused by the electric resistance.

[0003]

However, the torque detection by the potentiometer involves a displacement of the drive unit, resulting in a poor direct feeling and feeling, and a torque of the drive unit is elastically supported by a spring. There is a problem that transmission loss occurs and hysteresis is large.

[0004] Further, the torque detecting device using a potentiometer has a problem that the structure is complicated and the reduction in size and weight is limited, so that the cost cannot be avoided.

[0005] The present invention has been made in view of the above problems, and the object thereof is to provide a simple structure and strong strength.
An object of the present invention is to provide a torque detecting device which can be reduced in size and weight and cost, can provide a high feeling of feeling, is easy to handle and adjust, and is suitable for moving.

[0006]

In order to achieve the above object, an invention according to claim 1 includes a magnetic body which directly receives a reaction force of a driving unit caused by a torque in a torque transmission system;
The torque detecting device is characterized in that it includes a detection coil for extracting a reaction force acting on the magnetic material as a change in inductance by utilizing the change in the magnetic characteristics of the magnetic material.

A second aspect of the present invention is characterized in that, in the first aspect of the present invention, no rotational displacement is caused by the reaction force.

A third aspect of the present invention is characterized in that, in the first aspect of the present invention, a plurality of locations for receiving the reaction force are provided, and a change in magnetic characteristics at at least one location is detected.

According to a fourth aspect of the present invention, in the first aspect of the present invention, a reaction force adjusting mechanism for increasing or decreasing the magnitude of the reaction force by a link or a lever is provided.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the magnetic body is constituted by a load detecting element made of a piezoelectric material that does not involve displacement.

Therefore, according to the present invention, the reaction force acting on the magnetic material is taken out as a change in the inductance of the detection coil by utilizing the change in the magnetic characteristics of the magnetic material which directly receives the reaction force of the driving unit caused by the torque. Since the torque is detected by the method, the structure of the device is simplified, high strength is obtained, the size and weight can be reduced, the cost can be reduced, the handling is easy, and the device is suitable for transportation.

Also, since the detection does not involve a displacement, a high direct feeling and feeling can be obtained, the adjustment is easy, the hysteresis can be suppressed to a small value, and a high torque transmission can be achieved because no spring or the like is used. Efficiency can be ensured.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

<First Embodiment> FIG. 1 is a sectional view showing a basic configuration of a torque detecting device according to a first embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a detecting unit which constitutes a torque detecting device according to the present invention.
And a detection coil 3 disposed around the magnetic shield case 4 is housed in a magnetic shield case 4 made of a magnetic material. Here, the magnetic body 2 is made of iron, iron chromium, iron nickel,
Iron cobalt system, pure iron, iron silicon system, iron aluminum system,
It is made of a magnetic material such as a permalloy material, a soft magnetic material, or a giant magnetostrictive material.

Reference numeral 20 denotes a planetary gear mechanism, which comprises a sun gear 22 connected to a rotary shaft 21, a large-diameter ring gear 23, and a sun gear 22 which meshes with the sun gear 22 and rotates around the sun gear 22 while rotating. The planetary gear 24 includes a plurality of (in the illustrated example, five) planet gears 24 that revolve.
An arm 25 extends from the ring gear 23 in the tangential direction integrally therewith.
Is in contact with the upper end of the magnetic body 2 of the detection unit 1 via a buffer member 5 as shown. Note that the cushioning material 5 also serves as a magnetic shielding material.

When the rotating shaft 21 is driven to rotate at a predetermined speed, the rotation is transmitted to the planetary gear 24 via the sun gear 22, but the arm 25 integrally extending from the ring gear 23 is Since the tip spherical portion 25a is in contact with the magnetic body 2 of the detector 1, the ring gear 23 is practically fixed and does not rotate. Accordingly, the plurality of planet gears 24 revolve around the sun gear 22 while rotating, and the carrier (not shown) attached to these planet gears 24
4 is driven to rotate.

Incidentally, in the planetary gear mechanism 20,
A reaction force P proportional to the magnitude of the torque transmitted from the rotating shaft 21 is generated in the ring gear 23, and the reaction force P is received by the magnetic body 2 of the detection unit 1 via the cushioning material 5. A compressive load P acts on the body 2 in the axial direction.

As described above, when the compressive load P in the axial direction acts on the magnetic body 2 of the detection unit 1, the magnetic body 2
Of the detection coil 3 is reduced due to a decrease in the magnetic permeability of the detection coil 3.
Changes in proportion to the turns ratio. The magnetostriction effect is several hundreds to several thousand ppm in the case of a giant magnetostrictive material, and
ppm or less.

The voltage change V of the detection coil 3 is transmitted to a signal processing circuit (not shown), and the signal processing circuit amplifies the voltage change V of the detection coil 3 caused by the compression load P as an output signal. The output signal is input to a CPU (not shown) as a calculating means, and the CPU calculates the magnitude of the torque transmitted from the rotating shaft 21 based on the input output signal.

In the above description, the torque detecting device according to the present embodiment uses the reaction force (compression load) P generated by the torque.
The torque is detected by taking out the reaction force P as a change in the inductance of the detection coil 2 by utilizing the change in the magnetic properties of the magnetic body 2 which directly receives the torque, so that the structure of the device is simplified and a high strength is obtained. This makes it possible to reduce the size and weight and reduce the cost, facilitate handling, and be suitable for transportation.

Further, since the detection does not involve a displacement, a high direct feeling and feeling can be obtained, the adjustment is easy, the hysteresis can be suppressed to a small value, and a high torque transmission can be achieved because no spring or the like is used. Efficiency can be ensured.

Further, in the detecting section 1 of the torque detecting device according to the present invention, since the magnetic body 2 and the detecting coil 3 are magnetically shielded by the magnetic shield case 4,
The detection result is hardly affected by magnetic influence, and the torque can be detected with high accuracy.

In the present embodiment, the detection coil 3
Although only the excitation coil is used, an excitation coil magnetically coupled to the detection coil 3 may be used in combination (the same applies to the following embodiments).

As shown in FIG. 2, a bolt 26 is disposed on the opposite side of the spherical portion 25a of the arm 25 from the detecting portion 1 and a preset load is applied to the arm 25 by the bolt 26 to thereby provide the arm 25 with a predetermined load. The vibration of the arm 25 can be suppressed.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a cross-sectional view showing the basic configuration of the torque detection device according to the present embodiment. In this figure, the same elements as those shown in FIG. Description is omitted.

In the present embodiment, the detectors 1 are located above and below the spherical portion 25a of the arm 25 of the planetary gear mechanism 20.
1 and 1 are arranged, and the two detection devices 1
A preset load is applied to each of the magnetic bodies 12 and 2 by a bolt 26. The upper detecting unit 11 is configured by housing a magnetic body 12 and a detection coil 13 disposed around the magnetic body 12 in a magnetic shield case 14 made of a magnetic material. Arm 25
Abuts on the spherical portion 25a of the helical member.

In the process in which the rotation of the rotating shaft 21 is transmitted to the carrier (not shown) by the planetary gear mechanism 20, a reaction force (compression load) acts on the magnetic body 2 of the lower detection unit 1 from the arm 25. Then, a large compressive force acts on the magnetic body 2 and a compressive force acting on the magnetic body 12 of the upper detecting section 11 decreases, so that the inductance change in the detecting coils 3 and 13 of the detecting sections 1 and 11 is reduced. A difference occurs, and the difference between the inductance changes causes the detection coils 3, 13
The generated voltages V1 and V2 also exhibit different values.

The voltages V1 and V2 generated in the detection coils 3 and 13 are affected by environmental conditions (temperature and humidity) and the like. In the torque detection device according to the present embodiment, the voltages V1 and V2 The difference (V1−V2) is calculated as the differential output ΔV
As a result, the sensitivity of torque detection can be increased, and the torque can be detected with high accuracy without being affected by environmental conditions and the like.

In this embodiment, the same effects as those of the first embodiment can be obtained. However, since the accuracy is high, a large amplification factor can be obtained.
Inexpensive general-purpose materials can be used in place of expensive giant magnetostrictive materials as 2, so that the cost of the torque detecting device can be further reduced.

The magnetic members 2 and 12 and the detection coils 3 and 13 may be housed in one integrated magnetic shield case 4 as shown in FIG. 4, or as shown in FIG. The end spherical portion 25a of the arm 25 may be connected to the intermediate portion of the two magnetic bodies 2. With such a configuration, the torque detecting device can be further reduced in size and weight, and the number of parts and cost can be reduced.

Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 6 is a cross-sectional view showing the basic configuration of the torque detection device according to the present embodiment. In this figure, the same elements as those shown in FIG. 1 are denoted by the same reference numerals.

In the present embodiment, the planetary gear mechanism 2
The arm 25 is also used as a magnetic body of the torque detecting device, and the detecting unit 1 of the torque detecting device houses the arm 25 as a magnetic body, the detecting coil 3 disposed around the arm 25, and the detecting coil 3. It is constituted by a magnetic shield case 4.

The spherical portion 25a of the arm 25 is fixed, and when the arm 25 is deformed by the reaction force acting on the arm 25 to generate a distortion, the arm 25 is moved in accordance with the distortion. Since the magnetic permeability changes and the inductance of the detection coil 3 changes, and a voltage is generated in the detection coil 3 due to the change in the inductance, the torque transmitted from the rotary shaft 21 is detected in the same manner as described above. Also, the same effect as in the first embodiment can be obtained.

If the detection coils 3 and 13 are respectively arranged in a bifurcated shape as shown in FIG. 7 or as a bifurcated shape having a predetermined angle α as shown in FIG. Thus, a compressive force acts on one 25A and a tensile force acts on the other 25B, so that differential detection becomes possible as in the second embodiment, and the torque detection accuracy can be improved.

As shown in FIG. 9, a non-contact type load detecting element 7 and a detecting coil 3 are disposed in the vicinity of an arm 25 functioning as a magnetic body. A change in the magnetic characteristics of the arm 25 caused by the torque may be detected in a non-contact manner.

<Fourth Embodiment> Next, a fourth embodiment of the present invention will be described with reference to FIGS. FIG.
0 and FIG. 11 are basic configuration diagrams of the torque detection device according to the present embodiment.

In the example shown in FIG. 10, a ring gear 23 receiving a reaction force in the planetary gear mechanism 20 is formed as a magnetic body of a torque detector, and a fixed portion 23a is provided on the outer periphery thereof.
The detection coil 3 is arranged in the fixed portion 23a, and these are covered with the magnetic shield case 4 to form the detection portion 1.

In the planetary gear mechanism 20, the reaction force acting on the fixed portion 23a of the ring gear 23 changes the magnetic permeability of the fixed portion 23a, causing a change in the inductance of the detection coil 3 and detecting the change in inductance. Since a voltage change occurs in the coil 3, the torque transmitted from the rotating shaft 21 is detected in the same manner as described above, and the same effects as in the first embodiment can be obtained in the present embodiment.

In the example shown in FIG. 11, a stopper 100 fixed to a case is used instead of the fixing portion 23a, and the effect is the same. Further, since the change in the voltage generated in each detection coil 3 differs before and after the fixed portion 23a or the stopper 100, the difference in the voltage generated in each detection coil 3 is detected to increase the torque transmitted by the rotating shaft 21. It can be detected with high accuracy.

As shown in FIG. 12, a fixed portion 23a is provided on a part of the ring gear 23, and a non-contact type load detecting element 7 similar to that shown in FIG. Is arranged, a compressive force acts on one region and a tensile force acts on the other region from the fixed portion 23a due to the reaction force acting on the ring gear 23, so that the voltage generated in each detection coil 3 , The torque transmitted by the rotating shaft 21 can be detected with high accuracy.

<Fifth Embodiment> Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 13 is a cross-sectional view showing a basic configuration of the torque detection device according to the present embodiment.

In the present embodiment, the planetary gear mechanism 2
Arm 25 by the reaction force generated in the ring gear 23
The load P acting on the spherical portion 25a is distributed and received by the two detectors 1 via the plate 8. In addition, in each detection unit 1 shown in FIG. 13, 2 is a magnetic material, 3 is a detection coil, 4 is a magnetic shield case, and 5 is a cushioning material.

Thus, according to the present embodiment, the same effect as that of the first embodiment can be obtained, and the magnitude of the load acting on the magnetic body 2 of each detection unit 1 can be reduced by half. Therefore, the strength and sensitivity of the magnetic body 2 can be adjusted, and a small-diameter magnetic body 2 can be used, so that the excitation frequency can be increased to increase the sensitivity and responsiveness. The effect of reducing material costs and reducing costs can be obtained.

As shown in FIG. 14, if the load P acting on the spherical portion 25a of the arm 25 is received by the plurality of fixing members 9 and one detection unit 1 via the plate 8, the detection unit 1 The load acting on the magnetic body 2 can be further reduced.

<Sixth Embodiment> Next, a sixth embodiment of the present invention will be described with reference to FIG. FIG. 15 is a cross-sectional view showing the basic configuration of the torque detection device according to the present embodiment. In this figure, the same elements as those shown in FIGS. 13 and 14 are denoted by the same reference numerals.

In this embodiment, the load P acting on the spherical portion 25a of the arm 25 of the planetary gear mechanism 20 is applied to the link 10
And the detection unit 1 receives it.

Here, one end of the link 10 is rotatably connected to a shaft 27 so that a load P1 acts on the shaft and a load P2 acts on the magnetic body 2 of the detecting unit 1. Then, the following equation is established from the balance of the forces.

P = P1 + P2 (1) Further, assuming that the distances from the point of application of the load P to the points of application of the loads P1 and P2 are L1 and L2, respectively, as shown in FIG. Then, the following equation is established.

P1 · L1 = P2 · L2 (2) From the above equations (1) and (2), the load P is represented by the loads P2 and L1,
It is obtained by the following equation using L2.

P = (L1 + L2) P2 / L1 (3) Therefore, if the load P2 acting on the detection unit 1 is detected, the load P can be obtained by the above equation (3), so that the torque T is calculated by the following equation. be able to.

T = P · r (4) where r is the distance from the center of the rotating shaft 21 to the point of application of the load P. Therefore, according to the present embodiment, the load P2 acting on the detection unit 1 is It can be increased or decreased arbitrarily.

<Application Example> Next, an application example of the torque detecting device according to the present invention will be described with reference to FIGS.
FIG. 16 is a side view of the electric bicycle, and FIG. 17 is a sectional view of a torque detecting unit of the electric bicycle.

First, the schematic structure of the electric bicycle 30 shown in FIG. 16 will be described.

In the electric bicycle 30, reference numeral 31 denotes a steering wheel, reference numeral 32 denotes a front wheel, reference numeral 33 denotes a down tube, reference numeral 34 denotes a seat tube, reference numeral 35 denotes a seat (saddle), reference numeral 36 denotes a rear wheel, and reference numeral 37 denotes a rear wheel.
Denotes a wheel sprocket, and a power unit 38 is disposed substantially at the lower center of the vehicle body.

The power unit 38 is constructed by arranging a driving system by human power and an auxiliary power system by an electric motor 39 in parallel. The power unit 38 combines the human power (pedal force) of the occupant and the auxiliary power and outputs the combined power. The crankshaft 40 is supported rotatably. Cranks 41 are attached to the left and right sides of the crankshaft 40, and a pedal 42 is rotatably supported at an end of each crank 41. The power unit 38 is provided with a controller 43 for controlling the output (auxiliary power) of the electric motor 39 according to the magnitude of the torque input to the crankshaft 40 by human power.

A battery box 44 is removably mounted in a space below the seat 35 and surrounded by the seat tube 34 and the rear wheel 36. The battery box 44 is provided with a shrink pack. And a Ni-Cd battery (not shown) composed of a plurality of unit cells.

When the occupant steps on the pedal 42 to rotate the crankshaft 40, the torque input to the crankshaft 40 is detected by the torque detecting device shown in FIG. The output (auxiliary power) of the electric motor 39 is controlled according to the magnitude of the detected torque. Accordingly, in the power unit 38, the human power and the auxiliary power proportional thereto are combined and transmitted to the wheel sprocket 37 via a chain (not shown), and the wheel sprocket 37 and the rear wheel 36 are rotationally driven. Is driven by human power and auxiliary power proportional thereto.

The torque input to the crankshaft 40 by the occupant is detected by the same torque detecting device as in the first embodiment.

That is, in FIG. 17, reference numeral 45 denotes a housing of the power unit, 25 denotes an arm connected to a ring gear (not shown) of the planetary gear mechanism. Are in contact with the magnetic body 2 that constitutes the detecting unit 1. The detection unit 1 is configured by housing a rod-shaped magnetic body 2 and a detection coil 3 arranged around the magnetic body in a magnetic shield case 4 made of a magnetic material.

Thus, a reaction force proportional to the magnitude of the torque transmitted from the crankshaft 40 is generated in the ring gear of the planetary gear mechanism, and this reaction force is transmitted via the roller 46 and the cushioning member 5 to the detection unit 1. , A compressive load acts on the magnetic body 2 in the axial direction. The voltage change of the detection coil 3 caused by the compressive load is output to the controller 43 (see FIG. 16) as an output signal. Is entered. Then, the controller 43 calculates the magnitude of the transmission torque based on the input detection signal, and controls the output (auxiliary power) of the electric motor 39 according to the magnitude of the torque as described above.

Incidentally, as shown in FIG.
When a preset load is applied to the arm 25 by the bolt 26 screwed on the upper surface of the arm 25, the vibration of the arm 25 can be suppressed.

[0063]

As is apparent from the above description, according to the present invention, the reaction force acting on the magnetic body by utilizing the change in the magnetic characteristics of the magnetic body directly receiving the reaction force of the driving section caused by the torque. Is detected as a change in the inductance of the detection coil to detect torque, so the structure of the device is simplified and high strength is obtained, making it possible to reduce the size and weight and reduce the cost. It will be suitable.

Further, according to the present invention, since there is no displacement in the detection, a high direct feeling and feeling can be obtained, the adjustment is easy, the hysteresis can be reduced, and a spring or the like is used. Therefore, high torque transmission efficiency can be ensured.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a basic configuration of a torque detection device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a modification of the torque detection device according to Embodiment 1 of the present invention.

FIG. 3 is a sectional view showing a basic configuration of a torque detection device according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a modification of the torque detector according to Embodiment 2 of the present invention.

FIG. 5 is a cross-sectional view showing a modification of the torque detector according to Embodiment 2 of the present invention.

FIG. 6 is a sectional view showing a basic configuration of a torque detection device according to Embodiment 3 of the present invention.

FIG. 7 is a diagram showing a modification of the torque detection device according to Embodiment 3 of the present invention.

FIG. 8 is a diagram showing a modification of the torque detection device according to Embodiment 3 of the present invention.

FIG. 9 is a diagram showing a modification of the torque detector according to Embodiment 3 of the present invention.

FIG. 10 is a basic configuration diagram of a torque detection device according to Embodiment 4 of the present invention.

FIG. 11 is a basic configuration diagram of a torque detection device according to Embodiment 4 of the present invention.

FIG. 12 is a basic configuration diagram showing a modification of the torque detection device according to Embodiment 4 of the present invention.

FIG. 13 is a sectional view showing a basic configuration of a torque detecting device according to a fifth embodiment of the present invention.

FIG. 14 is a sectional view showing a modification of the torque detection device according to the fifth embodiment of the present invention.

FIG. 15 is a cross-sectional view illustrating a basic configuration of a torque detector according to Embodiment 6 of the present invention.

FIG. 16 is a side view of an electric bicycle showing an application example of the torque detection device according to the present invention.

FIG. 17 is a sectional view of a torque detector of an electric bicycle showing an application example of the torque detector according to the present invention.

FIG. 18 is a cross-sectional view showing a modified example of the torque detector of the electric bicycle, showing an application example of the torque detector according to the present invention.

[Explanation of symbols]

 1,11 detecting section 2,12 magnetic body 3,13 detecting coil 4,14 magnetic shield case 5,15 cushioning material 7 load detecting element 10 link

Claims (5)

[Claims] 1. A magnetic body which directly receives a reaction force of a driving unit caused by a torque in a torque transmission system, and a detection coil which extracts a reaction force acting on the magnetic body by using a change in magnetic characteristics of the magnetic body as a change in inductance. A torque detecting device comprising: 2. The torque detecting device according to claim 1, wherein a rotational displacement due to the reaction force is not accompanied. 3. The torque detecting device according to claim 1, wherein a plurality of portions receiving the reaction force are provided, and at least one change in magnetic characteristics is detected. 4. The torque detecting device according to claim 1, further comprising a reaction force adjusting mechanism for increasing or decreasing the magnitude of the reaction force by a link or a lever. 5. The torque detecting device according to claim 1, wherein the magnetic body is constituted by a load detecting element made of a piezoelectric material without displacement.