JPH03140831A - Angle-of-torsion detector and torque sensor - Google Patents

Abstract

PURPOSE:To detect the angle of torsion of a shaft to be measured with high accuracy by providing a pair of optical encoders on the same axis so as to provide a proper interval therebetween in the axial direction and inserting the shaft to be measured in the axial direction to fix the same to the rotary parts of the encoders. CONSTITUTION:Optical encoders 3, 4 are fixed to the support end plates 2 provided on both end parts of a main body case 1 on the same axis at a predetermined interval. A torsion bar 5 is inserted through the encoders 3, 4 at the axial core positions thereof to be fixed thereto. The detection signals from the encoders 3, 4 are inputted to an angle-of-torsion operation circuit and the angle-of-torsion of the torsion bar 5 between both encoders 3, 4 is operated and the operation result is inputted to a torque operation circuit and a torque value is operated from the angle of torsion and the torsional rigidity of the selected torsion bar 5 to be outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a torsion angle detection device and a torque sensor.

(Prior Art) Conventionally, a commonly known torque sensor is one in which a strain gauge is attached to a torsion bar and a torque value is calculated from a change in resistance value due to distortion of the torsion bar.

In addition, a pair of external gears are fixed to both sides of the torsion bar, and an internal gear is placed close to the outer periphery of the external gear, and a magnetic circuit is formed between them, and a coil is used to detect the phase difference between the teeth of both gears. A magnetic phase difference type torque sensor has also been proposed, in which a torque value is calculated from the phase difference detected by the torque sensor.

(Problem to be Solved by the Invention) However, in the strain gauge method described above, when the maximum measured value is 5 kgm using a certain torsion bar, the minimum resolution is coarse at about 0.5 kgm, the error is about 1%, and the response is Since the frequency is as slow as about 2.5 kHz, there is a problem in that it is impossible to construct a torque sensor with high precision and high speed response.

In addition, for magnetic phase difference torque sensors, the same (when the maximum measured value is 5 kgm, the minimum resolution is O, 1k
gm, the error is 0.1%, and the response is improved to about 20kHz, but it is not possible to obtain a torque sensor with even higher precision and faster response, and the output density of the detection signal per revolution is lower than that of the gear. Limited by the number of teeth, it is not possible to accurately detect torque changes, and furthermore, stable detection signals cannot be obtained in the case of low speed rotation. There was a problem in that the configuration was complicated.

Further, a similar problem occurs in a torsion angle detecting device for a shaft to be measured having a similar configuration.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, an object of the present invention is to provide a torsion angle detection device and a torque sensor that are capable of high-accuracy, high-speed responsive detection, and precise detection.

(Means for Solving the Problems) The torsion angle detecting device of the present invention has a pair of optical encoders disposed on the same axis at an appropriate interval of 4 to 4 mm in the axial direction, and It is characterized in that the shaft to be measured is inserted through the position and fixed to the rotating part of each encoder.

Further, the torque sensor of the present invention uses a torsion bar in place of the shaft to be measured, and also includes means for calculating a torsion angle between encoders based on detection signals from each encoder, and a means for calculating a torque value from the torsion angle. It is characterized by providing means.

It is also preferable that each encoder is provided with means for removably fixing the torsion bar, and that the torque value calculation means is provided with means for inputting the type of torsion bar so that the torsion bar can be replaced.

Further, the means for calculating the torsion angle includes a counter that counts the pulse signals output from each encoder, a means for performing interpolation calculation between the pulse signals from the elapsed time and the period of the pulse signal, and a signal of the counter and the interpolation calculation means. , and a torsion calculation means to which output signals from the position calculation means of each encoder are input.

(Function) According to the torsion angle detection device of the present invention, by using an optical encoder with high resolution and high speed response, the torsion angle of the measured shaft can be determined with high precision and high speed response from the difference in detection position by each encoder. It can be detected with In addition, it is possible to reliably detect whether the axis to be measured is stationary or rotating at high speed, and the number of slits in the code plate of the encoder can be much larger than in the case of gears, and the output density per revolution is high. , precise detection is possible.

Further, according to the torque sensor of the present invention, a torque value is calculated and output from the similarly detected torsion angle and the torsional rigidity of the torsion bar, and a torque sensor having high accuracy and high speed response can be obtained.

Furthermore, by allowing the torsion bar to be replaced, a wide range of torque can be detected with high accuracy.

Furthermore, if the measurement system is a system that rotates stably at a constant speed or with slow speed changes, it is possible to count the pulse signals output from the encoder and perform position detection in time division between the pulse signals. , high-precision detection is possible with a simple circuit configuration.

(Example) Hereinafter, a first example in which the present invention is applied to a torque sensor will be described.
This will be explained with reference to FIGS.

First, the overall structure of the torque sensor will be described with reference to FIG. 1. Reference numeral 1 denotes a main body case, and support end plates 2 are attached to both ends of the main body case. 3.4 are first and second optical encoders 3.4 disposed on both ends of the main body case 1 so as to be located on the same axis, and suitable mounting means are attached to the support end plate 2. It is fixed at . A torsion bar 5 is inserted and fixed at the axial center position of these encoders 3.4.

Next, the configuration of the first encoder 3 will be explained with reference to FIG. Note that the second encoder 4 also has the same configuration. 6
is a hollow rotary shaft that is fitted onto the torsion bar 5, and a support flange 6a for the cord plate 7 is provided on the outer periphery of the shaft. The support flange 6a has a code plate 7 on its surface.
The inner periphery of the two is abutted and fixed. The hollow rotating shaft 6 is rotatably supported by a support member 9 made of an annular plate via a pair of ball bearings 8. A code plate 7 is attached to the support member 9.
A detection head 10 is provided to detect the 0 rotation position. This detection head 10 irradiates the code plate 7 with laser light from a laser light source, and irradiates the photodetector with bright and dark fringes of a Fraunhofer diffraction image generated by slits regularly formed in the coat plate 7 through the slits. , is configured to output a rectangular wave detection signal corresponding to the slit interval based on the detection signal from the photodetector. 8a is
This is a fixing nut for the bearing 8, and is screwed onto the outer periphery of the hollow rotating shaft 6. Reference numeral 9a denotes a cover that covers the code plate 7 and the detector IO, and its outer circumference is fixed to the outer circumference of the support member 9.

A fixing means 11 is interposed between the outer circumferential surface of the torsion bar 5 and the inner circumferential surface of the hollow rotating shaft 6, and fixes the torsion bar 5 to the hollow rotating shaft 6 in an adjustable manner.
3, a pair of wedge-shaped sleeves 12a, 12b drawn together at 3, an angled sleeve 14 that engages with the inner periphery of these wedge-shaped sleeves 12a, 12b, and an angled sleeve 15 that engages with the outer periphery of the wedge-shaped sleeves 12a, 12b. It is composed of The outer periphery of the chevron-shaped sleeve 15 is divided into two parts at the central position in the axial direction, and an adjustment distance piece 16 is interposed therebetween.

The detection signals from the first and second encoders 3.4 are
As shown in the figure, the torsion angle calculation circuit 21 calculates the torsion angle of the torsion bar 5 between the encoders 3 and 4, and the result is input to the torque value calculation circuit 22. Further, a signal from a torsion bar selection circuit 23 is input to the torque value calculation circuit 22 . That is, as shown in FIGS. 4(a) to (C), for example, 1 kg
An appropriate torsion bar 5 is selected from among multiple types of torsion bars 5a to 5c designed according to the magnitude of the torque to be detected, such as for m, 10kgm, and 100kgm, and is inserted and fixed to the encoder 3.4. A signal specifying the type of the selected torsion bar is manually input to the torque value calculation circuit 22. The torque value calculation circuit 22 calculates a torque value from the torsion angle and the torsional rigidity of the selected torsion bar 5 and outputs it.

The configuration of the torsion angle calculation circuit 21 will be explained with reference to FIG.
8 is entered. Counters 25 and 26 count the number of pulses of the detection signal and input it to position calculation units 31 and 32. On the other hand, the time calculation units 27.28 measure the period T of the detection signal and the elapsed time A after detecting the reference phase and input them to the interpolation calculation unit 29.30.
At 9.30, A/T is calculated from the period T and the elapsed time A and inputted to the position calculation section 31.32. Position calculation section 3
1.32, the position for each slit pitch is detected by the signal from the counter 25.26, and the interpolation calculation unit 29.30
The position within the slit pitch is detected by the signal from. The calculation results from these position calculation sections 31, 32 are input to a twist calculation section 33, which calculates a twist angle from the difference in position detected by both encoders 3.4 and outputs the result.

Next, the operation of torque measurement will be explained. A torsion bar 5 is selected according to the approximate magnitude of the torque to be measured, and is inserted and fixed into each encoder 3.4 of the torque sensor. At that time, the torsion bar 5 is connected to each encoder 3.
The fastening bolt 1 is inserted into the hollow rotating shaft 6 of 4.
3 is loosened, the fixing means 11 is interposed between the inner circumferential surface of the hollow rotating shaft 6 and the outer circumferential surface of the torsion bar 5, and adjustment is made so that the axes of the torsion bar 5 and the hollow rotating shaft 6 coincide. while tightening the fastening bolts 13 to fix the torsion bar 5 to each encoder 3.4. Further, the type of the selected torsion bar 5 is input to the torsion bar selection circuit 23 using an appropriate input means. Note that both ends of the torsion bar 5 are connected to a rotating system whose torque is to be measured.

After the above settings are made, when the rotation system is driven, the torque acts on the torsion bar 5, causing the torsion bar 5 to twist in accordance with the torque. Then, a difference occurs between the detection positions by the first and second encoders 3.4 in accordance with the torsion of the torsion bar 5, so the torsion force calculation circuit 21 calculates the torsion angle of the torsion bar from the difference in detection positions. can do. When calculating this torsion angle, if the rotating system has a constant speed or a slow change in rotational speed, and a stable rotational state is maintained, the code plate 7 moves at a constant speed within each slit pitch with high accuracy. Therefore, even if position detection within the slit pitch is performed by time division using the torsion force calculation circuit 21 having the circuit configuration as shown in FIG. 5, highly accurate position detection is possible. Further, even if the waveform accuracy of the detection signal due to the light transmitted through the slit is poor, highly accurate position detection is possible without being affected by it. Therefore, highly responsive and highly accurate position detection is possible with a simple circuit configuration. A torque value calculation circuit 22 calculates torque from the torsion angle calculated in this way, and outputs the torque value.

11~ In a torque sensor using an optical encoder 3.4 as described above, if an optical encoder with an output pulse number of about 30,000 pulses per revolution is used, the same torsion bar as the conventional example is used. The maximum measured value is 5 using
kgm, it is possible to obtain a highly accurate and fast-responsive torque sensor with a minimum resolution of 0.04 kgm, an error of 0.01%, and a response of 30 to 300 kHz.

In the above embodiment, the torsion force calculation circuit assumes that position detection within the slit pitch is a constant velocity movement and performs time division. It goes without saying that this is a good thing, and in that case, it is possible to detect torque with high precision even when the rotation is stopped or when the rotation is at low speed and in an unstable rotation state.

In addition, although the above embodiment shows an example in which the present invention is applied to a torque sensor, the shaft to be measured may be inserted through the torsion bar instead of the torsion bar.
By configuring it to be fixed, it can also be used as a torsion angle detection device.

2 (Effects of the Invention) According to the present invention, by using an optical encoder with high resolution and high speed response, the torsion angle of the shaft to be measured can be detected with high precision and high speed response from the difference in the detection position by each encoder. can do. In addition, it is possible to reliably detect whether the axis to be measured is stationary or rotating at high speed, and the number of slits in the code plate of the encoder can be much larger than in the case of gears, and the output density per rotation is high. , precise detection is possible.

Further, according to the torque sensor of the present invention, a torque value is calculated and output from the torsion angle detected in the same manner and the torsional rigidity of the torsion bar, and a torque sensor having high accuracy and high speed response can be obtained.

Furthermore, by allowing the torsion bar to be replaced, a wide range of torque can be detected with high accuracy.

Furthermore, if the measurement system is a system that rotates stably at a constant speed or with small speed changes, it is possible to count the pulse signals output from the encoder and perform time-division position detection between the pulse signals. , it has great effects, such as enabling high-precision detection with a simple circuit configuration.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional front view showing the overall configuration of a torque sensor according to an embodiment of the present invention, FIG. 2 is an enlarged sectional front view showing the detailed configuration of an optical encoder used in the torque sensor, and FIG. A block diagram of the signal processing circuit of the same torque sensor, FIGS. 4(a) to 4(C) are front views of various types of torsion bars for replacement, and FIG. 5 is a block diagram of the torsion force calculation circuit. 29. 31, 3 0 2 - Interpolation calculation section Position calculation section Torsion calculation section

Claims (5)

[Claims] (1) A pair of optical encoders are arranged on the same axis with appropriate spacing in the axial direction, and the shaft to be measured is inserted through the axis position and fixed to the rotating part of each encoder. Torsion angle detection device. (2) A counter that counts the pulse signals output from each encoder, a means for performing interpolation calculation from the elapsed time and the period of the pulse signal between the pulse signals, and a position calculation based on the signals of the counter and the interpolation calculation means. 2. The torsion angle detection device according to claim 1, further comprising a torsion calculation means to which an output signal from the position calculation means of each encoder is input. (3) Arrange a pair of optical encoders on the same axis with appropriate spacing in the axial direction, and insert a torsion bar into the axial position and fix it to the rotating part of each encoder. 1. A torque sensor comprising means for calculating a torsion angle between encoders based on a detection signal of the encoder, and means for calculating a torque value from the torsion angle. (4) The torque sensor according to claim 3, wherein each encoder is provided with means for removably fixing the torsion bar, and means for inputting the type of torsion bar to the torque value calculation means. (5) The means for calculating the torsion angle includes a counter that counts the pulse signals output from each encoder, a means for performing interpolation calculation from the elapsed time and the period of the pulse signal between the pulse signals, and the counter and the interpolation calculation means. 5. The torque sensor according to claim 3, further comprising a means for calculating a position based on a signal, and a torsion calculating means to which an output signal from the position calculating means of each encoder is input.