JPS60243532A - Optical type torque detector - Google Patents

Abstract

PURPOSE:To omit a stroboscope and to make it possible to detect torque, by yielding Moire fringes by rotation of a pair or rotary plates having radial optical gratings caused by the torsion of a shaft member. CONSTITUTION:Optical gratings 5 of a first rotary plate 31 are continued in the radial direction linearly. Optical gratings 6 of a second rotary plate 32 are divided into both half parts 6a and 6b in the radial direction. The phases of both two parts 6a and 6b are made different by, e.g., 1/4 the pitch P of the gratings. When relative rotation is yielded between both rotary plates 31 and 32 due to the torsion of a shaft member 1, ring shaped Moire fringes are yielded by the gratings 5 of the rotary plate 31 and both half parts 6a and 6b of the gratings 6 of the rotary plate 32. Light is projected on the rotary plates 31 and 32 through a light projecting optical fiber 8 from a light source 10. The transmitted light is guided to first and second light detectors 111 and 112 through light receiving optical fibers 91 and 92. The output signals from the detectors are processed by a detecting circuit, and the displacement of the Moire fringes is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical torque detection device for detecting torsional torque of a shaft member such as a transmission shaft provided in a drive system of a vehicle.

As a conventional device of this kind, according to Japanese Patent Publication No. 57-4856, a striped pattern consisting of a group of parallel straight lines at equal pitches is applied to the outer peripheral surface of the shaft member, Position the camera, which is set on the L-plane f-plane, so that the striped pattern image and the negative overlap in the same size, and use a strobe once per rotation in synchronization with the rotation of the shaft member. illumination is performed, thus generating moire fringes on the pin surface of the camera according to the inclination of the striped pattern due to twisting of the detail material, and detecting the torsional shift torque of the detail material from the moire fringes. There are known devices that do this, but this requires strobe illumination that is synchronized with the rotation of the shaft member, which complicates the structure, and the torsional torque can only be detected at the time of strobe illumination, which limits the detection timing. This is accompanied by some inconvenience.

SUMMARY OF THE INVENTION In order to eliminate such inconveniences, the present invention aims to provide a device that does not require strobe illumination and can detect torque at any point in time. A pair of rotary plates are placed opposite each other,
Both rotating plates are connected at a predetermined interval to a shaft member whose torsional torque is to be detected, so that moiré fringes are generated in response to relative rotation of the two rotating plates as the shaft member is torsioned; The present invention is characterized in that a detection means for detecting the displacement of the moiré fringes is provided to detect the torsional torque of the shaft member.

The present invention will be explained below with reference to the illustrated embodiments.

In the drawings, fi+ indicates a shaft member such as a transmission shaft provided in the drive system of a vehicle, and (2) indicates a case into which the detail material ill is rotatably inserted, and the inside of the case (2) around the shaft member +11 is A pair of first and second rotary plates (1) (3x) are arranged in a space facing each other in the axial direction, and the two rotary plates (31, 32) are connected to connectors (4+) (4+) fixed thereto, respectively. 't) on the shaft member (1) at a predetermined distance.

Both rotary plates (31) (3 are made of a transparent material, for example, and a black optical grating (51 (6)
e The optical grating (5) formed on one of the rotary plates (3+) (5t), for example, the first rotary plate (31), is formed radially at a minute pitch, as shown in FIG. The optical grating (6) is continuous in a straight line in the radial direction, but is divided into a radially inner half (6a) and an outer half (6b). , both halves (6a)
(6b), the phases are made to differ from each other by, for example, A of the grating pitch P.

According to this, when the relative rotation of both rotary plates ('+) (3t) occurs due to the twist of the shaft member (1), the optical grating (5) of the first rotary plate (61), for example, As shown in Figure 4a, the outer half of the optical grating (6) of the second rotating plate (3,)
6a), the inner half (6b) of the optical grating (6) as shown in Figure 4 with a relative rotational displacement equivalent to ■.
, and then with a corresponding relative rotational displacement as shown in FIG. 40, the outer half (6a
), and then with a relative rotational displacement equivalent to 7P, the inner half (
6b), and with a relative rotational displacement equivalent to 1P, it twists into the same state as shown in Figure 4a, and as a result, the outer half of the shaft member (11), when viewed from a stationary system that does not rotate together with The state shown in FIG. 4 is shown in FIG. Ring-shaped moiré fringes are generated in and in the vicinity thereof, and a phase difference exists in each portion of A and B depending on the change in the relative rotational displacement of the two rotating bodies (31) and (3,). Moire fringes occur periodically.

In the drawing, (7) shows a detection means provided to detect the displacement of the moiré fringes of the dove. A light emitting optical fiber (8) is provided, and a pair of light receiving optical fibers (91) (9) are provided on the other side corresponding to each part A and B, and the light emitting optical fiber (8) The transmitted light of the A and B portions of the light beam from the light source (11) is transmitted through the 6 light-receiving optical fiber (9I) (9ρ) to the first photodetector (corresponding to the A portion). 11,) and a second photodetector (11,) corresponding to part B, respectively.
) (11t) is processed by a detection circuit to detect the displacement of the moiré fringes.

Note that the light receiving optical fiber (9+) (9z)i can also be placed on the same side as the light emitting optical fiber (8) by using a mirror or the like.

To describe the detection circuit in detail based on the block diagram shown in FIG. 5, each waveform shaper (12+) (12t) and each inverter (131) ( 132) and a first photodetector (
The first inverter (131) connected to the second photodetector (11, 1
3,) to generate a pulse as shown in FIG. output from a pair of first and second AN
D gate (15+) (input to 1rJ and the second
The output of the inverter (132) is
51) and the second AND gate (is2) via the inverter (IQ), and both gates (15,) (15
The first AND gate ('s+
) is added to the output pulse from the second AND gate.
) The output pulse from (152) is input as a subtraction pulse, and the torsion torque can be calculated and output as appropriate using the output processing circuit based on the count signal from the counter (Lη).

That is, when the amount of torsion increases due to the increase in the torsional torque of the shaft member (1), the state shown in FIG. 4 a changes from the state shown in b to the state shown in FIG. Moiré fringes occur in the first part before the A part, and the output of the second inverter (1St) rises, causing the first AND game to rise.
A high level signal is input to (15,) and a low level signal is input to the second AIJD game (151), and then moiré fringes are generated in the A part in the transition to the state shown in FIG. When the output of the first inverter (1it) rises, a trigger pulse is generated from the one-shot multivibrator I, which causes one addition pulse to be input from the first AND gate (151) to the counter αD, and the same applies thereafter. Each time a relative rotation of one pitch of the grating occurs, one addition pulse is input to the counter αη. Also, twist, ri 1j
When the relative rotational displacement of both rotary plates (3I) and (32) decreases due to a decrease in k, moiré occurs in part A before part B in the transition from the state shown in Figure 4 d to the state shown in 0. Stripes occur;
At this time, the second AND gate (u inverter α at 15ρ)
Since a high level signal from e and a trigger pulse from the pie break I are input, a subtraction pulse is input from the gate (15m) to the counter αD, and thus υ is input by the count signal of the counter (17). The current amount of twist of the shaft member (11), and therefore the twist torque can be detected.

In addition, the optical grating (51) formed on both rotating plates (3r) (3J)
(6) is not limited to the type of the above embodiment,
For example, as shown in FIG. 7, the grids (51(6)') may be formed in a radial manner and intersect with each other. The resulting ring-shaped moire fringes are displaced radially outward or inward depending on the relative rotation direction of both rotary plates (3+) (3J), and a moire pattern is generated at any one point in the radial direction by relative rotation of one grating pitch P. The torsional torque can be detected in the same way as above by measuring the displacement direction of the moiré fringes and the number of moiré fringes that cross all of one arbitrary point using a minimum of two photodetectors when the fringes cross once. .

Moreover, instead of the above-mentioned rotary plates (31) and (32), a pair of rotary cylinders are connected with a space between them in the detailed material, one of them is inserted into the other so that they face inside and outside in the radial direction, and both of them are connected. Although it is possible to obtain the same operation as in the above embodiment by forming optical gratings at a predetermined pitch in the same direction on each rotating cylinder, it is difficult to form optical gratings on such a cylinder, and it is difficult to do so. It is necessary to connect the cylindrical body to the shaft member so as not to oscillate, and the installation becomes troublesome, so it is more advantageous to use a rotary plate as in the present invention.

As described above, according to the present invention, ring-shaped moiré fringes are generated due to the displacement of the optical grating of each rotary plate due to the relative displacement of the pair of rotary plates due to the torsion of the shaft member, and It is possible to detect the torsion by detecting the displacement of the moiré fringes without using strobe illumination, which eliminates the need for strobe illumination, which makes the device cheaper, and allows detection to be performed at any time without any restriction on the timing of detection. It is possible to detect the torsional torque of the rotary plate, and it also forms an optical grating on the rotary plate, which is easier to manufacture and attach to the shaft member than when using a rotary tube as described above, and it can be mounted on a vehicle etc. to prevent torsion. This has an advantageous effect when controlling an engine, transmission, etc. according to torque.

[Brief explanation of the drawing]

Figure 1 is a cutaway side view of one example of the device of the present invention, Figures 2 and 3 are diagrams showing the lattice shape of each rotating plate, and Figure 4a.
, ba, (l is a diagram showing the displacement of the optical grating due to the relative rotational displacement of both rotating plates, FIG. 5 is a block diagram of an example of a detection circuit that is a component of the detection means, and FIG. A line diagram showing the overnight output changes of each photodetector of the circuit, and Fig. 7 is a line diagram showing the lattice shape of another embodiment. (1)...Shaft member (31) (32)... Rotating plate (51 (63... Optical grating (7)... 2 people outside the detection means Figure 4 (a) (b) (C) (d) Figure 6 ( b) Relative mouth weight λ wo 萱 =

Claims (1)

[Claims] A pair of rotary plates each having a radial optical grating are arranged opposite to each other, and both rotary plates are connected at a predetermined distance to a shaft member whose torsional torque is to be detected. Moiré fringes are generated in accordance with the relative rotation of the rotary plate,
1. An optical torque detection device comprising: a detection means for detecting displacement of moiré fringes with a moire pattern, and detects torsional torque of the detail material.