JP3278772B2 - Torque sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque sensor suitable for detecting a small torque applied to a shaft at the time of stop or high-speed rotation.

[0002]

2. Description of the Related Art In a conventional torque sensor, as shown in FIG. 4, identical gears 12, 12 'made of a ferromagnetic material are mounted on both sides of a torsion bar 11, and each gear 1
Electromagnetic pickup 1 facing the outer peripheral surface of 2, 12 '
3, 13 'was installed. Therefore,
If torque is applied to both ends of the torsion bar during rotation,
The torsional twist causes a phase difference between the gears on both sides. The magnitude of the torque was detected from the phase difference.

As another torque detecting method, as shown in FIG.
Spiral amorphous magnetic alloy 17, forming a spiral shape
18 is adhered, and coils 14 and 15 are arranged concentrically on the outside thereof. When a torque is applied to the shaft, a tensile stress is generated in one amorphous magnetic alloy 17 and a compressive stress is generated in the other amorphous magnetic alloy 18, and the generated stress changes the magnetic permeability of the amorphous magnetic alloy. , 15 and the magnitude and direction of the torque are detected by the differential output of the two coils.

[0004]

Problems to be Solved by the Invention In the case of the first method,
The shaft must be rotating to detect the phase difference. Therefore, when trying to measure torque at rest, a special rotating device is required and the structure becomes complicated. In addition, when attempting to detect a minute torque, a long torsion bar is required to generate a phase difference required for detection at both ends of the shaft, and there is a problem that the length of the detection device is long and miniaturization is difficult. Was. In the second method, since the amorphous magnetic alloy is bonded to the shaft, the shaft and the amorphous magnetic alloy have different coefficients of thermal expansion, so that a measurement error occurs due to a temperature change. Also, since there is little distortion with a small torque,
There was a problem that the generation of stress was slight and it was difficult to detect a minute torque. . In addition, both of the above techniques cannot measure the number of rotations. SUMMARY OF THE INVENTION It is an object of the present invention to provide a small-sized torque sensor capable of detecting a minute torque and a rotation speed from a standstill to a high-speed rotation while eliminating the above-mentioned disadvantages of the prior art.

[0005]

The above object is achieved by detecting the displacement of an elastic cylindrical surface which is deflected by a torque provided in a torque transmission system by a non-contact displacement meter installed outside the torque transmission system. Is done. That is, an elastic cylinder having a plurality of slits provided at equal intervals in a direction oblique to the circumferential direction between the load shaft and the drive shaft of the torque transmission shaft is inserted, and the drive shaft, the elastic cylinder, and the rotation center of the load shaft are rotated. And place them so that they match. This can be achieved by a torque detecting device having a configuration in which a non-contact displacement sensor is disposed at right angles to a cylindrical surface so as to detect a radial displacement of a slit forming portion of the elastic cylindrical body. The non-contact displacement meter has an eddy current method,
A capacitance type, an optical type, and the like can be used.

[0006]

[Function] Due to the torque applied to the load shaft, the elastic cylindrical body is twisted on both sides, and in the oblique slit forming part in the center, if the torque is applied in the direction where the pulling force acts on the slit, it is narrowed and the diameter is reduced. , In the opposite direction,
Deforms to expand in diameter. Since the amount of deformation is proportional to the magnitude of the torque, the magnitude and direction of the torque can be known by detecting with a non-contact displacement meter.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. FIG. 1A shows an embodiment of the present invention. A plurality of slits 2 are formed at equal intervals, usually in an angle range of 20 to 70 degrees, at an arbitrary angle other than 0 and 90 degrees with respect to the circumferential direction of the center of the cylinder 1 made of an elastic body. A non-contact displacement sensor 4 is installed at the axial center of the slit forming section 3 at right angles to the cylindrical surface. Now, when a torque is applied in the direction of the arrow in FIG. 1 (b), the slit forming portion 3 is narrowed and changes so that its diameter becomes small as shown in FIG. When a torque is applied in the opposite direction as shown in FIG. 1 (c), the slit forming portion 3 expands in the opposite direction and the diameter increases. Since the amount of deformation is proportional to the magnitude of the torque, the output of the non-contact displacement sensor 4 decreases in the case of a deformation in which the diameter is reduced, and increases in the case where the diameter is expanded, with respect to the no-load state. . By detecting the increase or decrease of the output level, the magnitude and direction of the torque can be known.

FIG. 2 (a) shows a second embodiment of the present invention.
Slits 2 and 2 'having an inclination are formed, and non-contact displacement sensors 4' and 4 "are installed at the center of each of the slit forming portions 3 'and 3" so as to face the cylindrical surface at right angles. Now, when a torque acts in the direction of the arrow shown in FIG. 2 (b), the slit 3 'on the left side is narrowed and its diameter shrinks, and the slit 3' on the right side expands and expands in diameter. The polarity of the output of the non-contact displacement sensor installed opposite to the sensor is reversed, and the detection sensitivity can be doubled by detecting the difference.

FIG. 3 shows a third embodiment of the present invention, in which a plurality of oblique slits 2 are formed at equal intervals around the center of the elastic cylindrical body 1 in the axial direction, and a circumferential portion is formed in front of the slit. A marker 5 is partially formed, and the non-contact displacement sensor 4 faces the slit.
Are installed, and the photo sensor 6 is installed at a position corresponding to the marker 5. The output of the non-contact displacement sensor 4 is converted from an analog signal into a digital signal by an A / D converter 9 via an amplifier 7 and enters an arithmetic processing unit 10. When the elastic cylinder 1 rotates, the output of the non-contact displacement sensor 4 is shown in FIG. 4A where the eccentricity of the elastic cylinder 1 and the voltage output increase when the hill 3 passes in front of the non-contact displacement sensor 4. It takes shape. At this time, when the marker passes in front of the photo sensor once per rotation, a trigger signal shown in FIG. 4C is generated. Under no load condition, the peak of the waveform of the mountain that sequentially comes in accordance with the trigger signal is held, and when a load is applied, the radius of the elastic cylindrical body changes. Therefore, the output waveform of the non-contact displacement sensor 4 is It changes as shown in FIG. 4b. Therefore, the magnitude of the torque can be known by comparing the peaks of the waveforms of the peaks that come in order based on the trigger signal with those at the time of no load.
In addition, by comparing and measuring the time between peaks of the peak waveform with no load and with the load using a timer built in the arithmetic processing unit 10, fluctuations in the rotational speed can be measured simultaneously.

FIG. 5 shows a fourth embodiment of the present invention, in which a non-contact sensor 4 is installed in the center of a slit forming portion 3 inside an elastic cylindrical body 1. There is no need for a space for installing a non-contact displacement sensor outside the elastic cylindrical body 1, and the torque detection device can be made compact. In this embodiment, as in the second embodiment, the detection sensitivity can be increased by providing two slit forming portions in which the inclination directions of the slits are opposite to each other.

[0011]

According to the present invention, it is possible to provide a small and lightweight torque sensor capable of detecting a minute torque up to stop and high-speed rotation. In addition, fluctuations in rotation speed can be measured.

[Brief description of the drawings]

FIG. 1 is a perspective view of a first embodiment of the present invention.

FIG. 2 is a perspective view of a second embodiment of the present invention.

FIG. 3 is a perspective view and a signal processing system diagram of a third embodiment of the present invention.

FIG. 4 is a diagram showing an output voltage level from a non-contact displacement sensor according to a third embodiment.

FIG. 5 is a perspective view of a cross section of a main part of a fourth embodiment of the present invention.

FIG. 6 is a perspective view showing the principle of a first conventional torque detecting device.

FIG. 7 is a schematic diagram showing the principle of another conventional torque detection device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Elastic cylindrical body 2 Slit 3 Slit forming part 4 Non-contact displacement sensor 5 Marker 6 Photo sensor 7 Amplifier 8 Trigger signal forming circuit 9 A
/ D converter 10 arithmetic processing unit

Claims (4)

(57) [Claims] In a method for detecting the torque of a torque transmission system in a non-contact manner, a plurality of slits are formed in a part of an elastic cylinder at a regular interval around the entire circumference and oblique to the circumferential direction. A non-contact displacement sensor is provided facing the cylindrical surface of the torque sensor. 2. A plurality of oblique slits are formed at equal intervals in two axial directions of the elastic cylindrical body so that their inclination directions are symmetrical with respect to the circumferential direction, and each of the oblique slits faces the cylindrical surface of each slit forming part. 2. The torque sensor according to claim 1, wherein two non-contact displacement sensors are provided. 3. A plurality of slanted slits are formed at equal intervals around the center of the elastic cylinder in the axial direction, markers are formed on a part of the circumference, and a non-contact displacement sensor is formed facing the slits. 2. The torque sensor according to claim 1, wherein a reflection type sensor is installed corresponding to the marker position. 4. A plurality of oblique slits are formed at equal intervals all around the center of the elastic cylindrical body in the axial direction, and a non-contact displacement sensor is provided inside the cylindrical body so as to face the cylindrical surface of the slit forming part. The torque sensor according to claim 1, wherein