JPH0972795A - Torque sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a very small torque and a rotary speed at the rotation of high-speed from still state by detecting the displacement of an elastic body cylindrical surface which is deflected due to torque being provided at a torque transmission system using a non-contact displacement meter. SOLUTION: A plurality of slits 2 are formed at an equal space within an angle range of 20-70 degrees for the circumferential direction of the center of a cylinder 1 of an elastic body and a non-contact displacement sensor 4 is installed oppositely at right angle to a cylindrical shaft at the center in axial direction of a slit formation part 3. When a torque is applied in the direction of an arrow, the formation part 3 is constricted and the diameter decreases. Also, when a torque is applied in opposite direction, the formation part 3 is inflated oppositely and the diameter increases. Since the amount of deformation is proportional to the size of torque, the output level of the sensor 4 decreases when the diameter shrinks and increases when the diameter increases. By detecting the increase/decrease of the output level, the level and direction of the torque can be determined.

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 minute torque applied to a shaft when stopped or rotating at high speed.

[0002]

2. Description of the Related Art In a conventional torque sensor, as shown in FIG. 4, exactly the same 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 '
It had a structure with 3, 13 'installed. Therefore,
If torque is applied to both ends of the torsion bar during rotation,
The torsion is twisted and a phase difference occurs between the gears on both sides. The magnitude of torque was detected from this phase difference.

As another torque detecting method, as shown in FIG. 5, 45 ° and −45 with respect to the longitudinal direction of the shaft 16.
Helical amorphous thin magnetic alloy 17,
There is one in which 18 is adhered and coils 14 and 15 are concentrically arranged on the outside thereof. When torque is applied to the shaft, a tensile stress is generated in one of the amorphous magnetic alloys 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 as the inductance, 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 axis must be rotating to detect the phase difference. Therefore, when trying to measure the torque at rest, a special rotating device is required and the structure becomes complicated. In addition, when trying to detect a small torque, a long torsion bar is required to generate the phase difference required for detection at both ends of the shaft, and the total length of the detection device becomes long, making it difficult to miniaturize. It was Further, in the second method, since the amorphous magnetic alloy is adhered to the shaft, the thermal expansion coefficient of the shaft is different from that of the amorphous magnetic alloy, so that a measurement error occurs due to a temperature change. Also, since there is little distortion with minute torque,
There is a problem that the stress is slightly generated and it is difficult to detect a minute torque. . In addition, it is impossible to measure the number of revolutions with both the above techniques. SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the above-mentioned drawbacks of the prior art and to provide a small torque sensor capable of detecting a minute torque and a rotational speed during stationary to high speed rotation.

[0005]

The above object is achieved by detecting the displacement of the elastic cylindrical surface which is provided in the torque transmission system and is made to bend by the torque, by a non-contact displacement gauge installed outside the torque transmission system. To be done. That is, an elastic cylindrical body having a plurality of slits at equal intervals obliquely to the circumferential direction is inserted between the load shaft of the torque transmission shaft and the drive shaft, and the rotation center of the drive shaft, the elastic cylindrical body, and the load shaft is inserted. Place and combine so that the two match. This can be achieved by a torque detection device having a configuration in which a non-contact displacement sensor is arranged at a right angle to the cylindrical surface so that the radial displacement of the slit forming portion of the elastic cylindrical body can be detected. In addition, the non-contact displacement gauge, eddy current method,
Capacitance type, optical type, etc. can be used.

[0006]

[Operation] Due to the torque applied to the load shaft, both sides of the elastic cylindrical body are twisted, and in the diagonal slit forming part in the central part, when the direction of torque addition is the direction in which a tensile force acts on the slit, the diameter is reduced and the diameter is reduced. , In the opposite direction,
It deforms so that its diameter expands. Since this deformation amount is proportional to the magnitude of the torque, the magnitude and direction of the torque can be known by detecting it with a non-contact displacement meter.

[0007]

The present invention will be described below based on the illustrated embodiments. FIG. 1 (a) shows an embodiment of the present invention. A plurality of slits 2 are formed at regular intervals in an angular range of 20 to 70 degrees at an arbitrary angle other than 0 and 90 degrees with respect to a circumferential direction of a central portion of a cylinder 1 made of an elastic body. A non-contact displacement sensor 4 is installed facing the cylindrical surface at a central portion in the axial direction of the slit forming portion 3 at a right angle to the cylindrical surface. When torque is applied in the direction of the arrow in FIG. 1 (b), the slit forming portion 3 is squeezed and the diameter thereof changes so as to become smaller, as shown in FIG. When torque is applied in the opposite direction as shown in FIG. 1 (c), the slit forming portion 3 expands and the diameter increases. Since the amount of this deformation is proportional to the magnitude of the torque, the output of the non-contact displacement sensor 4 decreases in the case of the deformation in which the diameter shrinks with respect to the unloaded state, and the output level rises in the case of the diameter expanding. . The magnitude and direction of the torque can be known by detecting the increase / decrease in the output level.

FIG. 2 (a) shows a second embodiment of the present invention, in which the cylinders 1 made of an elastic material are provided in opposite directions to each other near the center.
Slits 2 and 2 ′ having an inclination are formed, and non-contact displacement sensors 4 ′ and 4 ″ are installed at the center of the slit forming parts 3 ′ and 3 ″ so as to face the cylindrical surface at right angles. When torque acts in the direction of the arrow shown in Fig. 2 (b), the left slit portion 3'is squeezed and its diameter shrinks, and the right slit portion 3 "expands and its diameter expands. The polarities of the outputs of the non-contact displacement sensor installed facing each other are opposite, 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 slanted slits 2 are formed at regular intervals in the central portion of the elastic cylindrical body 1 in the axial direction, and a circular slit is formed in front of the slit portion. A marker 5 is formed on a part of the non-contact displacement sensor 4 facing the slit.
And the photo sensor 6 is installed at a position corresponding to the marker 5. An output of the non-contact displacement sensor 4 is converted into 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 increases as the eccentricity of the elastic cylinder 1 and the hill portion 3 pass in front of the non-contact displacement sensor 4, as shown in FIG. Be in shape. At this time, when the marker passes in front of the photo sensor once per rotation, the trigger signal shown in FIG. 4c is generated. Now, in the no-load state, the peaks of the waveforms of the mountains that sequentially come based on the trigger signal are held, and when a load is applied, the radius of the elastic cylindrical body changes, so the output waveform of the non-contact displacement sensor 4 is It changes like FIG. 4b. Therefore, the magnitude of the torque can be known by comparing the peaks of the waveforms of the mountains that sequentially come with the trigger signal as a reference with those at no load.
Further, by comparing and measuring the time between peaks of the peak of the mountain with the timer built in the arithmetic processing unit 10 under no load and under load, the fluctuation of the rotation speed can be measured at the same time.

FIG. 5 shows a fourth embodiment of the present invention, in which the non-contact sensor 4 is installed inside the elastic cylindrical body 1 at the center of the slit forming portion 3. A space for installing a non-contact displacement sensor outside the elastic cylindrical body 1 is not required, and the torque detection device can be downsized. In the present embodiment, similarly to the second embodiment, the detection sensitivity can be increased by providing two slit forming portions whose slits are inclined in opposite directions.

[0011]

As described above, according to the present invention, it is possible to provide a small and lightweight torque sensor capable of detecting a minute torque even when stopped and rotated at a high speed. Furthermore, fluctuations in the number of revolutions can be measured.

[Brief description of 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 detection device.

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

[Explanation 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)

[Claims] 1. A method for detecting torque of a torque transmission system in a non-contact manner, wherein a plurality of slits oblique to the circumferential direction are formed at equal intervals on the entire circumference of a part of an elastic cylindrical body. A torque sensor characterized in that a non-contact displacement sensor is provided so as to face the cylindrical surface of. 2. An elastic cylindrical body is formed with a plurality of diagonal slits at two axial positions in a direction symmetrical to each other with respect to the circumferential direction at equal intervals and faces the cylindrical surface of each slit forming portion. 2. The torque sensor according to claim 1, wherein two non-contact displacement sensors are provided. 3. A plurality of diagonal slits are formed at equal intervals along the entire circumference of the central portion of the elastic cylinder in the axial direction, markers are formed on a part of the circumference, and a non-contact displacement sensor is faced to the slits. The torque sensor according to claim 1, wherein the torque sensor is installed and a reflection type sensor is installed corresponding to a marker position. 4. A non-contact displacement sensor is provided inside the cylindrical body by forming a plurality of diagonal slits at equal intervals around the central portion in the axial direction of the elastic cylindrical body and facing the cylindrical surface of the slit forming part. The torque sensor as set forth in claim 1, wherein: