JPH0467897B2 - - Google Patents

Description

TECHNICAL FIELD The present invention relates to a torque detection device, and, for example, to a torque detection device suitable for detecting steering torque in conjunction with a steering mechanism of a bicycle.

Prior art and its problems Conventional torque detection devices, for example, steering torque detection devices, have a strain gauge attached directly to the surface of the steering wheel's articulating shaft, and the strain of the articulating shaft during steering is measured electrically by a bridge circuit. There is a strain gauge type torque detection device that detects the However, in this type of detection device, since the strain gauge is directly attached to the surface of the connecting shaft, the gauge itself may be damaged or peeled off from the surface to which it is attached due to repeated stress during steering. This tends to cause inconveniences, making it unsuitable for use in automobile power steering systems.

In addition, a torsion bar (torsion bar) made of ferromagnetic material is installed in the steering wheel's articulating shaft, and an excitation coil and a detection coil are installed around the outer periphery of the torsion bar. There is a magnetostrictive torque detection device that detects steering torque using the magnetic field. According to this detection device, during steering, bending stress in an unspecified direction acts on the torsion bar in addition to the pure steering torque component, so that the distance between the torsion bar and the excitation and detection coils increases. It has the disadvantage that it is not held accurately and fluctuates. Therefore, it is difficult to ensure steering torque detection accuracy.

In addition, as a device for detecting steering torque, a torsion section that responds to torque changes is constructed in the steering wheel's articulating shaft, and torsional displacement during steering is detected using photodiodes, phototransistors, Hall ICs, etc. There is a device to detect it. However, these detection elements are susceptible to dirt, aging,
Because the detection characteristics change due to temperature changes, etc.
This is not satisfactory as a detector for automobiles, where the operating environment is harsh and the period of use is long.

Purpose of the Invention In view of the above-mentioned drawbacks, the present invention provides a torque detection device that is electrically stable, has high detection accuracy, and has excellent durability, weather resistance, and aging characteristics.
In particular, it is an object of the present invention to provide a device suitable for detecting steering torque of a steering wheel of an automobile.

SUMMARY OF THE INVENTION The present invention provides a rotatable torque detection shaft having an input end and an output end rotatable following the rotation of the input end in a housing, the input end side and the output end side of the shaft. and an electromagnetic detection unit for relative rotational displacement thereof, further, a power supply primary coil and a signal secondary coil are provided in the housing, and a power supply secondary coil and a signal primary coil are respectively provided on the input end side of the torque detection shaft, This torque detection device is capable of supplying a reference signal to a rotational displacement detection section and detecting a rotational displacement signal therefrom using a transformer principle in a mechanically non-contact configuration.

DESCRIPTION OF EMBODIMENTS FIG. 1 is a specific structural diagram showing a part of the torque detection device of the present invention in cross section.

A torque detection shaft 3 rotatable via a bearing 2 is provided within the annular housing 1 . One end of the torque detection shaft 3 functions as an input end 3a, and the other end functions as an output end 3b. That is, the output end 3b
can rotate following the rotation of the input end 3a by twisting the torque detection shaft 3 itself, and can detect torque according to the relative rotational displacement between the two.

The torque detection shaft 3 is covered with a sleeve 4,
One end is fixed to the input end 3a by a pin 5 so as to be rotatable together with the input end 3a, and the other end is supported by a bearing 6 so as to be rotatable relative to the output end 3b. has been done.

An annular power source primary coil 8 is fixed on the inner circumference of the housing 1 via an insulating member 7, and this coil is connected to an external AC power source (FIG. 3, 20) via a power input lead wire 9. be done. On the other hand, on the outer periphery of the sleeve 4, an annular power supply secondary coil 11 that is rotatable integrally with the sleeve 4 is disposed coaxially and facing the power supply primary coil 8 via an insulating member 10. Furthermore, the insulating member 10 includes an annular signal primary coil 1 that is rotatable integrally with the sleeve 4.
On the other hand, an annular signal secondary coil 13 is fixed to the insulating member 7 on the side of the housing 1 so as to coaxially face the signal primary coil 12 . The signal secondary coil 13 is connected to a suitable external signal processing circuit (not shown) via a detection signal output lead 14.

The annular magnetic core 16 and the annular magnetic core 17 around which the detection coil 19 is wound constitute a torque detection section, and the magnetic core 16 is supported by the insulating member 10 on the sleeve 4 side, The magnetic core 17 is rotatable integrally with the end 3a, and the magnetic core 17 is rotatable integrally with the output end 3b, and is coaxially opposed to the magnetic core 16.

FIG. 2 is a cross-sectional view taken along the line - in FIG. 1 in order to further explain the specific structure of the torque detection section described above. As shown in the figure, the annular magnetic core 17 that is integrally formed with the output end 3b of the torque detection shaft 3 has the following functions:
The two notches 18a, 18 are arranged at an interval of approximately 180°, that is, in opposing positions with respect to the rotation axis.
It has b. An annular magnetic core 16 that is rotatable relative to the magnetic core 17 has four detection coils 19 arranged at equal intervals.
a to 19d are wound. With this configuration, each magnetic circuit formed between the magnetic cores 17 and 16 regarding the detection coils 19a to 19d changes according to the relative rotational displacement of the magnetic cores. Also, one pair 19 of the detection coils
Regarding a, 19b and the other pair 19c, 19d, increases and decreases in magnetic capacity due to relative rotational displacement of the magnetic cores are in a reciprocal relationship.

FIG. 3 shows an electrical circuit diagram of the torque detection device of the present invention.

An AC power supply 20 is connected via a power input lead 9 to both ends of the power supply primary coil 8, and an associated power supply secondary coil 11 is connected across the four detection coils 19.
It is connected to input terminals J ₁ and J ₂ of an AC bridge circuit constituted by a to 19d, respectively, and its output terminals J ₃ and J ₄ are connected to both ends of the signal primary coil 12. Both ends of the signal secondary coil 13 are connected to an output terminal OUT of the torque detection device via a detection signal output lead wire 14. The power supply primary coil 8, the power supply secondary coil 9, the signal primary coil 12, and the signal secondary coil 13 realize transfer of power or signals in a non-contact state through mutual inductance.

When a basic AC wave signal (FIG. 4A) is supplied from the AC power supply 20 to the power supply primary coil 8, an AC wave signal corresponding to the mutual inductance of these primary and secondary coils is induced in the power supply secondary coil 11. Applied to AC bridge circuit.

When no torque acts on the input end 3a of the torque detection shaft 3, as shown in FIG. 5A, the magnetic state of the pair of detection coils 19a, 19b and the other pair of detection coils 19c, 19d are exactly the same, therefore, the detection coils 19a to 19
No signal is output from the AC bridge circuit via d.

On the other hand, when torque is applied in one direction of rotation of the input end 3a, as shown in FIG. Since _the magnetization state or the increase/decrease of the magnetic capacitance is contradictory as described above, the _fourth
An output wave as shown in Figure B is generated as a detection signal. This detection signal indicates the relative rotational displacement between the input end 3a and output end 3b of the torque detection shaft 3.

Next, when a torque is applied to the input end 3a in the reverse rotation direction, the magnetic state applied to the detection coils 19a to 19d becomes as shown in FIG. 5c, and therefore,
At the output terminals J ₃ and J ₄ of the AC bridge circuit, as shown in FIG. 4c, an output wave having an opposite phase to the output wave in FIG. 4B is generated.

Peak value of the output wave of the AC bridge circuit (Fig. 4,
h ₁ and h ₂ are the magnitude of the torque, that is, the torque detection axis 3
It changes according to the relative rotational displacement between the input end 3a and the output end 3b.

The output signal of the AC bridge circuit obtained in this way is output from the output terminal OUT via the signal primary coil 12 and the signal secondary coil 13 as a detection signal of the torque detection device. This detection signal can be easily understood by those skilled in the art.
By performing phase detection processing using the signal waveform from the power source as a reference, it is possible to obtain a torque detection signal corresponding to the direction and magnitude of the torque at the input end 3a, as shown in FIG.

FIG. 7 shows another embodiment of the torque detection section,
Like FIG. 2, it is shown as a cross-sectional view taken along the line - of FIG. Torque detection axis 3
The annular magnetic core 17 fixedly installed at the output end is the same as the magnetic core shown in FIG. The detection coils 19a~
19d is wound around the respective divided magnetic core parts.

8 shows the magnetic state in the magnetic core structure shown in FIG. 7, and similarly to FIG. 5, FIG. 8A shows the state when no torque acts on the input end 3a of the torque detection shaft 3. FIG. 8B shows the state when torque is applied in one direction of rotation of the input end 3a, and FIG. 8C shows the state when torque is applied in the opposite direction of rotation of the input end 3a. are shown respectively.

Effects According to the present invention, the torque detection device itself is incorporated into the housing with an extremely simple structure, and furthermore, the reference signal is supplied to the torque detection device and the detection signal is taken out using a non-contact structure using the transformer principle. Because of this, it has excellent durability, weather resistance, and aging characteristics, and is highly reliable.

The torque detection device of the present invention, which can be expected to have the above-mentioned effects, is particularly suitable as a steering torque detection device for automobiles that are used in harsh environments and are used for a long period of time. In this case, for example, as shown in FIG. 9, a steering gear housing 1' is used as the housing, and the input end of the torque detection shaft is
It is linked to the steering wheel of the automobile, and its output end is connected to left and right wheels via a steering pinion gear 21 and a rack shaft 22. A torque detection signal outputted from the torque detection device is applied to an electric motor that drives the above-mentioned steering rack shaft 22 or a hydraulic power control device in order to control the direction and magnitude of steering assistance.

[Brief explanation of the drawing]

FIG. 1 shows the specific structure of the torque detection device of the present invention. FIG. 2 shows an embodiment of the torque detection section obtained along the line - in FIG. FIG. 3 shows an electrical circuit diagram of the torque detection device shown in FIG. FIG. 4 is a signal waveform diagram relating to the operation of the electric circuit of FIG. 3. FIG. 5 shows the relationship between the torque and the magnetic state in the torque detection section shown in FIG. 2. FIG. FIG. 6 shows the relationship between the output signal obtained by the torque detection device of the present invention and the direction of torque. FIG. 7 shows another embodiment of the torque detection section obtained along the line - in FIG. FIG. 8 shows the relationship between the torque and the magnetic state in the torque detection section shown in FIG. 7. FIG. 9 shows an example in which the torque detection device of the present invention is used in a steering gear. (Description of symbols), 1: Housing, 3: Torque detection shaft, 3a: Input end, 3b: Output end, 8: Power supply primary coil, 11: Power supply secondary coil, 12: Signal primary coil, 13: Signal secondary coil , 16, 17:
Annular magnetic core, 18a, 18b: notch, 19,
19a to 19d: detection coils.

Claims (1)

[Claims] 1. Torque is detected according to the relative rotational displacement between the input end of a torque detection shaft rotatably provided in the housing and the output end that is rotatable following the rotation of the input end. In the apparatus, a first annular magnetic core rotatable integrally with the input end of the torque detection shaft; disposed coaxially and facing the first annular magnetic core;
a second annular magnetic core rotatable integrally with the output end of the torque detection shaft; an AC bridge wound around the first annular magnetic core at approximately equal intervals and configured to detect the relative rotational displacement; and four detection coils connected to form a
an annular power supply primary coil fixed on the inner periphery of the housing; connected to an input terminal of the AC bridge circuit;
an annular power supply secondary coil disposed coaxially opposite the power supply primary coil and rotatable integrally with the input end of the torque detection shaft; and connected to the output terminal of the AC bridge circuit;
an annular signal primary coil that is rotatable integrally with the input end of the torque detection shaft; and an annular signal primary coil that is coaxially opposed to the signal primary coil in order to output a signal indicating the relative rotational displacement; A torque detection device comprising: an annular signal secondary coil fixed on an inner circumference; 2. In order to make the magnetic circuit formed together with the first annular magnetic core variable, the second annular magnetic core has the following features:
The torque detection device according to claim 1, characterized in that it has two notches spaced apart by approximately 180°. 3. The torque detection device according to claim 1 or 2, wherein the first annular magnetic core is formed from a single member. 4. According to claim 1 or 2, the first annular magnetic core is composed of four magnetic core parts, and the four detection coils are respectively wound around the four magnetic core parts. torque detection device.