JPH0159529B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a torque detector that photoelectrically converts a torsion angle proportional to the magnitude of torque generated on a torque transmission shaft into a phase difference signal.

Industrial Application Fields Torque is one of the important characteristic values that expresses the performance of prime movers such as engines and motors, and is used not only for inspection of prime movers or evaluation tests in research and development, but also for pumps, etc. connected to the prime mover. Torque measurement is essential in testing the performance of load devices.
Torque detectors are widely used for such tests.

Conventional technology First, the known ones will be briefly explained.

In FIG. 1, the bases of ring bodies 11 and 21 are fixed to two points on the shaft 1 spaced apart in the axial direction, and a disk 12 is fixed integrally to each open end surface thereof.
22 are closely facing each other, and the light emitting element 30 and the light receiving element 40 are sandwiched between a row of slits with a duty ratio of 1:1 at equal pitches bored around the periphery of the disks 12 and 22.
are placed facing each other.

In the above, the shaft 1 transmits torque, which causes the shaft 1 to be twisted, and the annular bodies 11 and 2 to be twisted.
When the axis 1 between the bases of the disks 1 is twisted and an angle θ occurs, the disks 12 and 22 also produce a relative angular displacement θ, and therefore the overlapping area of the slits of both disks 12 and 22 also undergoes an angular displacement. As a result, the amount of light that reaches the light receiving element 40 from the light projecting element 30 via its overlapping area changes, and the output of the light receiving element 40 changes.

Now, Figure 2 shows the slit 1 of the disks 12 and 22.
FIG. 2 is a diagram showing the relationship between the superposition state of 2' and 22' and the output of the light receiving element 40. First, when the disk 22 is angularly displaced with respect to the disk 12, and as a result, the slit 22' moves to the right with respect to the slit 12', the angular displacement θ and the overlapping area of both the slits 12' and 22' are calculated. To look at the relationship, if the disc 22 rotates to the right from a completely non-polymerized state (the left end of the slit 12' and the right end of the slit 22' are in the same position), the overlapping area will be equal to the angular displacement of the rotation. When the angular displacement reaches 1/2 of the slit pitch angle θp, complete polymerization occurs.
Subsequently, when the rotation angle is further turned to the right from θp/2, contrary to the above, it decreases in proportion to the rotational angular displacement, and when it reaches θp, it returns to its original state of non-polymerization. As described above, the overlapping area of the slits 12' and 22' changes in a triangular wave shape with respect to the angular displacement θ. Next, the overlapping area and the light receiving element 40
In order to look at the relationship between the output of
When the overlapping area changes in a triangular wave shape as described above due to the diffraction of light between 2 and 22, the circular shape of the light emitting surface and the light receiving surface, etc., the output of the light receiving element 40 becomes a sine wave or a sine wave. Very close to (b)
The following changes will occur.

Therefore, even if the output V〓 of this light receiving element 40 is measured, it is not proportional to the angular displacement θ, but is directly proportional to θ.
is not required.

To improve this, a phase difference method is already known as ``Photoelectric Torque Detector'' in Japanese Patent Laid-Open No. 55-164323. This is done by widening the gap between the disks 12 and 22 shown in FIG. 1 and supporting a cylindrical body via a bearing on the shaft between them. Another disk is fixed so as to face each other, and the light emitting element and the light receiving element are made to face each other by sandwiching the pair of disks on the left and right sides, and the cylindrical body is engaged with an external motor so that the rotation direction of the shaft is constantly adjusted. It is designed to rotate in the opposite direction. According to this, even if the shafts are stationary, the disks 12 and 22 and the other disks facing each other are rotated, so that each light receiving element receives one period of the sine wave for each rotation of the slit pitch θp. The phase difference α between the two sine waves is proportional to the angular displacement θ.

However, this product inevitably becomes large in size, has a complicated structure, requires a lot of effort to assemble, and has the problem of requiring strict machining accuracy for each component. There is. Furthermore, in this case, the lower the shaft rotation speed, the longer the detection gap becomes, and there remains the problem that torque cannot be determined with uniform response characteristics over a wide range of shaft rotation speeds.

Problems to be Solved by the Invention The present invention eliminates the above-mentioned drawbacks of the prior art and provides a torque control system that has a small number of parts, is small in size, and has high response characteristics over a wide range of shaft rotation speeds, including a stationary state. The aim is to provide a detector.

Means for Solving the Problems Therefore, the present invention utilizes the detection principle of the phase modulation detection method for detecting torsion angles, and uses two sensors whose bases are fixed at two points spaced apart in the axial direction. Two disks are placed close to each other and face each other, and a first row of slits is formed at equal pitches on the periphery of one disk, and a first row of slits is formed on the periphery of the other disk with different radii. Same pitch, 1/4 of each other
Second, third, fourth, and fifth slit rows that are shifted by pitch are respectively bored, and the first, second, and first slit rows are
and the third, first and fourth, and first and fifth slit rows, and the first, second, third, and fourth light emitting elements are placed on one side, and the first and second light emitting elements are placed on the other side. 2nd, 3rd, 4th
The first to fourth light receiving elements are arranged and facing each other.
The light-emitting elements were individually controlled by the lighting control unit to produce sine wave outputs with a phase difference of 90 degrees from each other, and the phase change of the combined output of the first to fourth light-receiving element outputs was measured. It is something.

Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

In FIG. 3 showing the mechanism, the shaft 1 and mounting rings 11 and 21, which are given the same numbers as in FIG. 1, are the same as those in FIG.
Discs 13 and 23 are fixed to the open end surface of 1, respectively. As shown in FIG. 4, first slit rows 14 with a duty ratio of 1:1 are formed at equal pitches on the disk 13, and the other disk 2 facing the first slit rows 14 has a duty ratio of 1:1.
As shown in FIG. 5, around 3, there are four slit rows, second to fifth, which have the same pitch as the first slit row 14, but whose arrangement positions are shifted by 1/4 pitch from each other. 15 to 18 are sequentially formed from the outer circumference to the inner circumference. Then, the first slit row 14
and each of the second, third, fourth, and fifth slit rows 15-
A pair of the first light emitting element 31 and the light receiving element 41, and a second light emitting element 3 are placed facing each other with the light emitting element 18 in between.
A pair of light emitting element 2 and light receiving element 42, a pair of third light emitting element 33 and light receiving element 43, and a pair of fourth light emitting element 34 and light receiving element 44 are arranged.

FIG. 6 shows the first to fourth light emitting elements 31 to 3.
This is an embodiment of the lighting control unit 50 that controls the amount of light emitted by the oscillator 51, and the sinωt and
The output terminals of cosωt are connected to the input terminals of the first and second light emitting elements 54 and 55, respectively, and to the input terminals of the inverters 52 and 53, respectively. And inverter 52,5
The output terminals of No. 3 are connected to input terminals of drive circuits 56 and 57 for the light receiving elements 33 and 34, respectively.

In the above, the oscillator 51 oscillates a sine wave and a cosine wave with a predetermined angular velocity ω (=2π/T) based on the time interval T for which the torque is to be determined, and inputs the sine waves and cosine waves to the drive circuits 54 and 55. At the same time, when the inverters 52 and 53 invert the signal and input it to the drive circuits 56 and 57, the respective drive circuits 54 to 57 cause the light emitting elements 31 to 34 to generate a sine wave, a cosine wave, and an inverted sine wave, respectively. , the amount of light emission is controlled in the form of an inverted cosine wave. However, in this case, there is no negative luminescence amount, so it is within a certain positive luminescence amount range, for example, 0.
This will cause periodic changes between ~2A,
The amount of light emitted by the first to fourth light emitting elements 31 to 34 is A(sinωt+1), A(cosωt+1), and A(−
sinωt+1) and A(-cosωt+1). and,
The amount of each light passes through the overlapping portions of the first slit row 14 and the second, third, fourth, and fifth slit rows 15 to 18 facing each other, and reaches the corresponding light receiving elements 41 to 44. where it is converted into an electrical signal. Therefore, the light receiving elements 41 to 4
The electrical signals generated in 4 are also a sine wave, a cosine wave, an inverted sine wave, and an inverted cosine wave with an angular velocity of ω, and their wave heights depend on the light transmission area, that is, the size of the overlapping area of each opposing slit. This will change.

Now, as already explained in Figure 2 above,
The overlapping area of the two slit rows changes like a triangular wave while the angular displacement θ changes from 0 to the slit pitch θp, but the relationship between the overlapping area and the amount of light transmitted through it changes like a sine wave. Therefore,
The outputs of the light receiving elements 41 to 44 each have an angular velocity ω
While changing periodically, the height also changes in the form of a sine wave, a cosine wave, an inverted sine wave, and an inverted cosine wave depending on the angular displacement θ. That is, the amount of light emitted from each of the light emitting elements 31 to 34 described above does not reach the light receiving elements 41 to 44 when the two opposing slit rows are completely non-polymerized, and the output of the light receiving elements 41 to 44 at that time is assumed to be Letting 0, the output when completely polymerized is 0, and let α (=2πθ/θp) be the electrical angle corresponding to the angular displacement θ when the slit pitch angle θp is 2π, then the light receiving elements 41 to 44 The outputs e ₁ to e ₄ are expressed as follows.

e ₁ = (B/2) (sinα+1) (sinωt+1) e ₂ = (B/2) (cosα+1) (cosωt+1) e ₃ = (B/2) (-sinα+1) (-sinωt+1) e ₄ = (B/ 2) (-cosα+1) (-cosωt+1) In the end, these outputs e ₁ to _{e 4} have an angular velocity of ω, and are carrier waves whose phases are shifted by 90 degrees from each other, each having a phase shift of 90 degrees and an angular displacement of θ. The amplitude is modulated sinusoidally by the corresponding electrical angle α.

Hereinafter, each of these outputs e ₁ to _{e 4} will be added and combined by the adder 60, and the output e will be as follows.

e=B [cos(ωt-α)+2] Therefore, this composite output e is a sine wave output of the angular velocity ω, and its phase α changes in accordance with the angular displacement θ. Therefore, by measuring the phase α of this composite output e with reference to either the output of the oscillator 51 or its inverted output, the angular displacement θ, i.e., is determined every predetermined period T (=2π/ω) , a torque proportional to that is required.

Note that in the above embodiment, the light receiving elements 41 to
Although the case where the outputs of the light receiving elements 41 to 44 are added as they are is illustrated, the same effect can be obtained by removing the DC component through a filter and then adding them.
44 may be replaced with a common light receiving element to also have a combining function.

Effects As described above, the present invention enables mutual angular displacement by disks that are relatively angularly displaced according to the torsion angle θ.
A change in the overlapping of the slits is caused in a group of four pairs of slit rows with a phase shift of 90 degrees, and the amount of light emitted to each overlapping portion is also changed in the form of a sine wave with a phase shift of 90 degrees. , and by extracting the combined output of the amount of light transmitted through it, the twist angle is converted into a phase change of the combined output.
Torque, which is proportional to the torsion angle, can be extracted at every fixed period of the composite output, and the torque can be obtained with high responsiveness over a wide range of shaft rotational speeds, from when the shaft is stationary to high speeds.

[Brief explanation of drawings]

Fig. 1 is a front view showing a known detection unit, Fig. 2 is an explanatory diagram of its operation, Fig. 3 is a front view showing an embodiment of the detection mechanism of the present invention, and Figs. FIG. 6 is a side view showing an embodiment, and FIG. 6 is a block diagram showing an embodiment of the lighting control section of the present invention. 13,2
3: Disc, 14-18: Slit example, 31-3
4: light emitting element, 41 to 44: light receiving element, 50: lighting control section.

Claims (1)

[Claims] 1. Two disks whose bases are fixed at two points spaced apart in the axial direction are placed close to each other, and a first row of slits are bored at equal pitches on the periphery of one disk. , second, third, fourth, and fifth slit rows are arranged on the periphery of the other disk having different radii, at the same pitch as the first slit row, but whose arrangement positions are shifted by 1/4 pitch from each other.
The first and second slit rows are drilled on one side of each pair of the first and second, first and third, first and fourth, and first and fifth slit rows. ,
The third and fourth light emitting elements are arranged and the amount of light emitted is controlled by the lighting control unit separately in the form of a sine wave with a phase shift of 90 degrees from each other, and an output corresponding to the combined light amount of the amount of transmitted light of each. Torque detection device that extracts the amount of change in phase.