JPH11281505A - Torque detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torque detecting device which is simple in structure, is high in strength, can be reduced in size, weight, and cost, is capable of obtaining satisfactory feeling, is easily handled and adjusted, and is suitably movable. SOLUTION: A detecting coil 2 is arranged in the vicinity of the surface of a sprocket (a torque transmitting member) 4 constituting a torque transmitting system and at a fixed part which is not in contact with the sprocket 4 or rotated. The sprocket 4 is magnetized by the detecting coil 4, and torque is detected by extracting the changes in the magnetic characteristics of the sprocket 4 caused by torque as the changes in the inductance of the detecting coil 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque transmission member which is magnetized by a detection coil disposed in the vicinity of a plane of a planar torque transmission member constituting a torque transmission system. The present invention relates to a torque detecting device configured to extract a change in stress as a change in inductance of the detection coil.

[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, in the torque detection by the potentiometer, the sense of directness is impaired because the drive unit is displaced, and the feeling is deteriorated because the applied force is not transmitted directly to the other party. Further, since the driving section is elastically supported by the spring, there is a problem that torque transmission loss occurs and hysteresis increases.

Further, the torque detecting device using a potentiometer has a complicated structure, and there is a limit in reducing the size and weight.
There was a problem that costs were unavoidable.

[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 good feeling, is easy to handle and adjust, and is suitable for moving.

[0006]

According to a first aspect of the present invention, there is provided a torque transmitting member which rotates in the vicinity of a surface of a torque transmitting member constituting a torque transmitting system without contacting the torque transmitting member. A detection coil is arranged in a fixed portion that is not used, the torque transmission member is magnetized by the detection coil, and a change in magnetic characteristics of the torque transmission member caused by torque is taken out as a change in inductance of the detection coil.

According to a second aspect of the present invention, in the first aspect of the invention, the torque detecting portion of the torque transmitting member is formed of a flat surface.

According to a third aspect of the present invention, in the first aspect of the invention, the torque detecting portion of the torque transmitting member is located at a position symmetrical with respect to a rotation center, and the center is coaxial with the rotation axis of the torque transmitting member. It is characterized by being.

According to a fourth aspect of the present invention, there is provided a signal transmission coil electrically connected to the detection coil for transmitting a voltage change of the detection coil, and the signal transmission coil electrically insulated from the signal transmission coil. And an exciting coil for transmitting a change in the inductance of the detection coil to a control circuit via a signal transmission coil, and a torque detection device provided with the control circuit.

According to a fifth aspect of the present invention, in the fourth aspect, a magnetic path of the detection coil is formed by the torque transmitting member and the magnetic core, and the torque transmitting member and the magnetic core are directly or buffered. It is characterized in that it is tightly fixed via a material.

Therefore, according to the present invention, since the torque is detected by taking out the change in the magnetic characteristics of the torque transmitting member caused by the torque as the change in the inductance of the detection coil, 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 is obtained and the feeling is good.
Further, the adjustment is easy, the hysteresis can be suppressed to a small value, and a high torque transmission efficiency can be secured because no spring or the like is used.

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

In FIG. 1, reference numeral 1 denotes a detecting unit constituting a torque detecting device according to the present invention, which comprises a ring-shaped detecting coil 2 and a magnetic core 3 which covers and magnetically shields the coil. I have.

The detecting coil 2 constituting the detecting section 1 rotates in the direction of the arrow in the figure and transmits torque via the chain 5 in the vicinity of one surface of a sprocket 4 constituting a planar torque transmitting member. , Is arranged at a fixed portion that is not contacted and does not rotate away from the sprocket 4,
It is wound parallel to the sprocket 4.

In order to impart magnetic anisotropy to the sprocket 4, as shown in FIG. 3, a part of the magnetic path is formed concentrically with the detection coil 2 on the surface facing the detection coil 2. A plurality of grooves or slits 4a are formed by cutting with a width approaching. As shown in FIG. 4, if the grooves or slits 4a are formed in two rows on the inner and outer peripheries at opposite angles, differential detection becomes possible and more accurate detection becomes possible. Also, plating, etching,
Other surface treatments may be performed or a magnetic material thin film such as an amorphous material may be bonded.

The sprocket 4 is magnetized by the detection coil 2, and a stress is generated in the sprocket 4 by a torque. The change in the stress causes a change in the magnetic permeability of the sprocket 4 due to the magnetostriction effect. 2
Changes in inductance. Then, the voltage at both ends of the detection coil 2 changes due to the change in the inductance of the detection coil 2.

The voltage change of the detection coil 2 is transmitted to a signal processing circuit (not shown), and the signal processing circuit amplifies the voltage change of the coil caused by the torque 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 by the sprocket 4 based on the input output signal.

In the above, the torque detecting device according to the present embodiment detects the torque by extracting the change in stress of the sprocket 4 caused by the torque as the change in the inductance of the detecting coil 2, so that the structure of the device is simplified. Thus, high strength can be obtained, miniaturization and weight reduction and cost reduction can be achieved, handling is facilitated, and the device is suitable for transportation.

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

Further, in the detecting section 1 of the torque detecting device according to the present invention, since the detecting coil is magnetically shielded by the magnetic core 3, the detection result is hardly influenced by the magnetic field and the torque is high. It can be detected with high accuracy.

Further, the durability of the torque detecting device is increased because the torque is detected in a non-contact manner, and the detection result is affected by the rotation fluctuation of the sprocket 4 because the torque is detected over the entire circumference of the sprocket 4. It is difficult to detect the torque with high accuracy.

In addition, since the detected surface of the sprocket 4 is a flat surface, high processing accuracy can be ensured on the detected surface. Further, the gap between the detection coil 2 and the magnetic core 3 and the sprocket 4 can be easily managed.

As shown in FIG. 5, if the detection coil 2 is wound around the sprocket 4 in a plane spiral, a stronger magnetic field is generated by the detection coil 2, so that the torque detection accuracy can be further improved. .

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a side view of a chain sprocket of a bicycle including the torque detecting device according to the present embodiment.

In FIG. 6, reference numeral 4 denotes a drive chain sprocket which constitutes a planar torque transmitting member in a bicycle, and is driven by a pedal crank shaft (not shown) to rotate in the direction of the arrow shown in the figure, and the rotation is wound around the periphery. The chain 5 is transmitted to the rear wheel (not shown).

Thus, in the present embodiment, a magnetic field extends along the circumferential direction of the sprocket 4 on the outer surface side of the chain sprocket 4 on one detecting coil 2 constituting the detecting section 1 of the torque detecting device according to the present invention. In the present embodiment, the magnetic characteristics change of the chain sprocket 4 caused by the torque is taken out as the inductance change of each detection coil 2 in the same manner as in the first embodiment, so that the torque is obtained. Detection can be performed in a non-contact manner, and the same effect as in the first embodiment can be obtained.

Further, since the direction of the magnetic field matches the direction of the stress applied to the sprocket 4 (circumferential direction) as compared with the first embodiment, a groove or the like for imparting magnetic anisotropy which is essential in the first embodiment. Is unnecessary, and the structure is simplified accordingly.

As shown in FIG. 7, if two detection coils 2 are arranged on the outer surface side of the chain sprocket 4, differential detection becomes possible, and torque can be detected with higher accuracy.

Although not shown, four or more detection coils 2 are arranged in the same direction as described above around the entire surface of the chain sprocket 4 in a non-contact manner to change the magnetic characteristics due to the stress change. Is detected, the detection result is hardly affected by the rotation fluctuation of the chain sprocket 4, similarly to the first embodiment, and the torque can be detected with high accuracy.

Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 8 is a plan sectional view of a power unit of an electric bicycle including the torque detecting device according to the present embodiment, and FIG. 9 is a configuration diagram of a planetary gear mechanism of the power unit.

A power unit 1 for an electric bicycle shown in FIG.
At 0, reference numeral 11 denotes a crankshaft, which is connected to a housing 13 via left and right bearings 12.
And a crank 14 is attached to both ends thereof. Although not shown, a pedal is supported at the end of each crank 14.

A planetary gear mechanism 16 is provided on the crankshaft 11.
The sun gear 17 and the ring gear 18 pivotally supported by the crankshaft 11 and a plurality of planetary gears 19 that mesh with the sun gear 17 and the ring gear 18 and revolve while rotating.

A torque arm 20 is connected to the outer periphery of the sun gear 17, and as shown in FIG. By being fixed to the housing 13, the rotation is prevented.

The ring gear 18 is connected to the crankshaft 11.
A rivet 23 is attached to a resultant shaft 22 rotatably supported above, and a bevel gear 22 a is integrally formed at an inner end of the resultant shaft 22, and the bevel gear 22 a is provided outside the housing 13 at the other end of the resultant shaft 22. Has a drive sprocket 24 attached thereto.

Further, a carrier 26 is rotatably supported on the crankshaft 11 via a one-way clutch 25. Each of the planetary gears 19 is mounted on the carrier 26 on the carrier 26.
7 supported.

On the other hand, in FIG. 8, reference numeral 28 denotes an electric motor for generating auxiliary power, which is provided at the end of a drive shaft 29 which is rotated by the electric motor 28 via a planetary roller type speed reducer 35 and a one-way clutch 36. Is bevel gear 3
The bevel gear 30 is meshed with a bevel gear 22a formed integrally with the inner end of the resultant shaft 22.

Here, as shown in FIG. 9, a detection coil 2 constituting a torque detection device according to the present invention is disposed at one place on the outer periphery of the torque arm 20 in a non-contact manner and fixed to the housing 13 side. ing.

When the occupant steps on a pedal (not shown) to rotate the crankshaft 11, the rotation is transmitted to the carrier 26 via the one-way clutch 25, and the carrier 26 is driven to rotate together with the crankshaft 11. You. Here, the sun gear 17 of the planetary gear mechanism 16 and the torque arm 2
When the carrier 26 is driven to rotate, the planetary gears 19 supported by the carrier 26 revolve around the sun gear 17 together with the carrier 26 and rotate around the shaft 27 when the carrier 26 is driven to rotate. And ring gear 1
In order to rotationally drive the motor 8, human power is transmitted to a resultant shaft 22 connected to the ring gear 18.

Incidentally, in the planetary gear mechanism 16,
The torque arm 20 produces a reaction force proportional to the magnitude of the torque input by the human input to the crankshaft 11, and the reaction force causes a stress change in the torque arm 20. By extracting the change in the magnetic characteristic of the portion a shown as the change in the inductance of the detection coil 2, it is possible to detect the manual torque input to the crankshaft 11.

When the human input torque input to the crankshaft 11 is detected as described above, a controller (not shown) controls the current supplied to the electric motor 28 so that the magnitude is proportional to the human input torque. The auxiliary power is transmitted to the resultant shaft 22 via the drive shaft 29 and the bevel gears 30 and 22a.

Accordingly, the human power of the occupant and the auxiliary power from the electric motor 28 are combined by the combined shaft 22, and the combined shaft drives the combined shaft 22 and the driving sprocket 24. The rotation of the driving sprocket 24 is transmitted to a driven sprocket (not shown) and a rear wheel via a chain (not shown), and the rear wheel is driven to rotate by human power and auxiliary power having a magnitude proportional thereto, whereby the electric bicycle runs. I'm sullen.

As shown in FIG. 10, the two detecting coils 2 constituting the torque detecting device according to the present invention are arranged on both sides of the lever 20a of the torque arm 20 with the lever 20a interposed therebetween.
The human-powered torque input to the crankshaft 11 may be detected by extracting a change in the magnetic characteristics of the portions b and c of the torque arm 20 as an inductance change of each detection coil 2.

<Fourth Embodiment> Next, a fourth embodiment of the present invention will be described with reference to FIGS. Note that FIG.
FIG. 12 is a front sectional view of a pedal crank portion of a bicycle provided with the torque detecting device according to the present embodiment, and FIG.
It is a line sectional view.

In FIGS. 11 and 12, reference numeral 11 denotes a crankshaft rotatably supported by a bottom bracket 31 constituting a part of a vehicle body frame. (Shown) is attached, and a pedal 15 is pivotally supported at an end of each crank 14.

A drive sprocket 24, which is a torque transmitting member, is connected to the inside of one crank 14 of the crankshaft 11, and a ring-shaped magnetic core 3 is provided on the inner end surface of the drive sprocket 24. It is attached by means such as screwing, bonding, and holding metal. A ring-shaped excitation and detection coil 2 is housed in the magnetic core 3 at a distance from the inner end face of the drive sprocket 24. The excitation and detection coil 2 and the magnetic core 3 are used in the present invention. The detection unit 1 of the torque detection device is configured.
The magnetic core 3 side of the drive sprocket 24 is subjected to magnetic anisotropic processing such as grooves as in the first embodiment.

Further, a signal transmission coil 6 is provided on the crankshaft 11, and signal transmission coils 6 and 7 are fixed to an end face of the bottom bracket 31 which is a fixed side, and a control circuit 8 is mounted on the bottom bracket 31. Is attached.

Here, the excitation and detection coil 2 is electrically connected to the signal transmission coils 6 and 7, and both signal transmission coils 6 and 7 are radially opposed to each other, and both are magnetically connected. And mechanically configured to be relatively rotatable. The signal transmission coil 7 is a signal transmission coil 6.
Is electrically insulated to excite the signal transmission coil 6, to which an AC voltage is applied by the control circuit 8.

Thus, the torque detecting device according to the present invention
It is configured to include the excitation and detection coil 2, the signal transmission coils 6 and 7, and the control circuit 8. The operation of the torque detection device will be described below.

When the occupant steps on the pedal 15, human power is transmitted to the crankshaft 11, and the crankshaft 11 and the driving sprocket 24 are driven to rotate. The rotation of the driving sprocket 24 is transmitted via a chain and a driven sprocket (not shown). Is transmitted to the rear wheels to drive the rear wheels.

By the way, in the process of transmitting the above-mentioned human power, a stress change occurs in the driving sprocket 24 due to the torque, and due to the stress change, the magnetic permeability of the driving sprocket 24 changes due to the magnetostriction effect, and the inductance of the detection coil 2 changes. . Then, a voltage is generated in the detection coil 2 due to the change in inductance of the detection coil 2.

The voltage change of the detection coil 2 is transmitted to the control circuit 8 via the signal transmission coils 6 and 7. Then, the control circuit 8 amplifies the voltage change of the detection coil 2 caused by the torque transmitted by the driving sprocket 24 as an output signal, and the output signal is input to a CPU (not shown) as a calculating means. The magnitude of the torque transmitted by the driving sprocket 24 is calculated based on the output signal.

In the above description, the torque detecting device according to the present embodiment detects the torque by extracting the change in the magnetic characteristics of the sprocket 24 caused by the torque as the change in the inductance of the detection coil 2, so that the structure is simplified. The same effects as those of the first embodiment, such as high strength, small size, light weight and cost reduction, and easy handling can be obtained.

Incidentally, as shown in FIG. 13, the detection coil 2 may be an inner and an outer two. In this case, the driving sprocket 2
4, the magnetic core 3 side is subjected to magnetic anisotropic processing such as grooves as in the first embodiment. Further, as shown in FIG. 14, the detection coil 2 and the magnetic core 3 may be attached to the bottom bracket 31 which is a fixed side.

<Fifth Embodiment> Next, a fifth embodiment of the present invention will be described with reference to FIGS. FIG.
5 is a front sectional view of a pedal crank portion of a bicycle provided with the torque detecting device according to the present embodiment, and FIG.
FIG. 13 is a sectional view taken along line C. In these figures, the same elements as those shown in FIGS. 11 and 12 are denoted by the same reference numerals, and description thereof will be omitted below.

In this embodiment, four detection coils 2 are provided on the inner and outer peripheral portions of a sprocket 24 which is a torque transmitting member.
The torque transmitted by the sprocket 24 is detected by winding a and 2b.

Since the stress generated in the sprocket 24 changes in the radial direction, there is a difference between the voltages V1 and V2 generated in the detecting coils 2a and 2b arranged apart in the radial direction. By detecting (V1−V2) as the differential output ΔV, the sensitivity and accuracy of torque detection can be increased.

Further, according to the present embodiment, a change in the magnetic characteristics of the sprocket 24 can be directly taken out as a change in the inductance of the detection coils 2a and 2b, so that the signal level can be increased. In this case, the groove processing on the surface of the sprocket 24 becomes unnecessary.

Furthermore, even if the processing accuracy of the torque detecting portion of the sprocket 24 is poor, the torque detecting accuracy is not affected by the processing accuracy of the torque detecting portion, so that the processing of the torque detecting portion is facilitated and the cost of the torque detecting device is reduced. Is achieved.

As another structure for obtaining a differential output, the structure shown in FIGS. 17 to 19 can be considered. still,
17 is a front sectional view of a pedal crank portion of a bicycle showing a modification of the torque detecting device according to the present embodiment, FIG. 18 is a sectional view taken along line DD of FIG. 17, and FIG. 19 is a torque according to the present embodiment. It is a front sectional view of the pedal crank part of the bicycle which shows the other modification of a detection device. In these figures, the same code | symbol is attached | subjected to the same element as FIG. 15 and FIG.

That is, in the example shown in FIGS. 17 and 18, four sets of a pair of detection coils 2a and 2b wound around different cross-sectional areas of the sprocket 24 are arranged on the same circumference. Since the stresses generated in the portions having different cross-sectional areas are different, the voltages V1 and V2 generated in the detection coils 2a and 2b are different from each other, and the difference between them (V1-V
By detecting 2) as the differential output ΔV, the sensitivity and accuracy of torque detection can be improved. In this case, the groove processing on the surface of the sprocket 24 becomes unnecessary.

In the example shown in FIG. 19, four pairs of detection coils 2a and 2b wound around the sprocket 24 at an angle of 45 ° with respect to the rotation direction are arranged on the same circumference. With respect to the rotation direction of the sprocket 24,
Since the stresses generated in the portions inclined by 5 ° are different, there is a difference between the voltages V1 and V2 generated in the respective detection coils 2a and 2b, and the difference (V1-V2) between the two is detected as the differential output ΔV. Thereby, the sensitivity and accuracy of torque detection can be increased. In this case, the groove processing on the surface of the sprocket 24 becomes unnecessary.

[0064]

As is clear from the above description, according to the present invention, the torque is detected by taking out the change in the magnetic characteristics of the torque transmitting member caused by the torque as the change in the inductance of the detection coil. The structure is simplified, high strength is obtained, downsizing and weight reduction and cost reduction are possible, handling becomes easy, and it is suitable for transportation.

Further, according to the present invention, since there is no displacement in the detection, a high direct feeling is obtained and the feeling is good. Further, the adjustment is easy, the hysteresis can be suppressed to a small value, and a high torque transmission efficiency can be secured because no spring or the like is used.

[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 sectional view taken along line AA of FIG.

FIG. 3 is a diagram showing magnetic anisotropic processing on a sprocket surface.

FIG. 4 is a diagram showing magnetic anisotropic processing on a sprocket surface.

FIG. 5 is a view similar to FIG. 2, showing a modified example of the torque detection device according to the first embodiment of the present invention.

FIG. 6 is a side view of a chain sprocket of a bicycle including the torque detecting device according to Embodiment 2 of the present invention.

FIG. 7 is a side view of a chain sprocket of a bicycle including the torque detecting device according to Embodiment 2 of the present invention.

FIG. 8 is a plan sectional view of a power unit of an electric bicycle including a torque detecting device according to Embodiment 3 of the present invention.

FIG. 9 is a configuration diagram of a planetary gear mechanism of a power unit of an electric bicycle including a torque detection device according to Embodiment 3 of the present invention.

FIG. 10 is a configuration diagram of a planetary gear mechanism of a power unit of an electric bicycle, showing a modification of the torque detection device according to Embodiment 3 of the present invention.

FIG. 11 is a front sectional view of a pedal crank portion of a bicycle showing a modification of the torque detection device according to Embodiment 4 of the present invention.

FIG. 12 is a sectional view taken along line BB of FIG. 11;

FIG. 13 is a front sectional view of a pedal crank portion of a bicycle showing a modification of the torque detection device according to Embodiment 4 of the present invention.

FIG. 14 is a front sectional view of a bicycle pedal crank part showing a modification of the torque detection device according to Embodiment 4 of the present invention.

FIG. 15 is a front sectional view of a pedal crank portion of a bicycle including a torque detection device according to Embodiment 5 of the present invention.

16 is a sectional view taken along line CC of FIG.

FIG. 17 is a front sectional view of a pedal crank portion of a bicycle showing a modification of the torque detection device according to Embodiment 5 of the present invention.

18 is a sectional view taken along line DD of FIG. 17;

FIG. 19 is a front sectional view of a pedal crank portion of a bicycle showing a modification of the torque detection device according to Embodiment 5 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Detection part 2, 2a, 2b Detection coil 3 Magnetic core 4, 24 Sprocket (torque transmission member) 6 Signal transmission coil 7 Excitation coil 8 Control circuit

Claims (5)

[Claims] 1. A detection coil is disposed in a fixed portion that is not in contact with the torque transmission member and that does not rotate in the vicinity of a surface of the torque transmission member that forms a torque transmission system, and the detection coil is used to control the torque transmission member. A torque detecting device which magnetizes and takes out a change in magnetic characteristics of a torque transmitting member caused by a torque as a change in inductance of the detection coil. 2. The torque detecting device according to claim 1, wherein the torque detecting section of the torque transmitting member is formed by a plane. 3. The torque transmitting member according to claim 1, wherein the torque detecting portion of the torque transmitting member is located at a position symmetrical with respect to a rotation center, and the center is coaxial with a rotation axis of the torque transmitting member.
The torque detecting device according to any one of the preceding claims. 4. A signal transmission coil electrically connected to the detection coil for transmitting a voltage change of the detection coil, and electrically isolated from the signal transmission coil to excite the signal transmission coil and detect the signal. A torque detecting device comprising: an exciting coil that transmits a change in coil inductance to a control circuit via a signal transmission coil; and the control circuit. 5. The magnetic path of the detection coil is formed by the torque transmitting member and the magnetic core, and the torque transmitting member and the magnetic core are closely fixed to each other directly or via a buffer material. 5. The torque detecting device according to 4.