JPS61187627A - Method for measuring torque - Google Patents

Abstract

PURPOSE:To enable the accurate measurement of torque, by automatically correcting a torque measuring error due to the change in the mount angle of a composite sensor by combining inclination angle measuring sensors. CONSTITUTION:In two circular rings 7, 8 with slits, the length of the slit part of the circular ring 8 in the radius direction is made longer than that of the other circular ring 7 and a pair of light emitting and receiving optical fibers 21, 22 are arranged to said part is inclination angle measuring sensors in the same way as existing light emitting and receiving optical fibers 11, 12. From the relation between a time permitting the transmission of light through the slits of the circular rings 7, 8 and a light blocking time, angle of inclination is operated by a torque operation apparatus 17. The operation result is displayed by one of display apparatus 18-20 to make it possible to know the angle of inclination of an optical axis at the measuring time of torque and the resetting to a normal state is also enabled. By this method, the effect of the angle of inclination contained in a light receiving time within one cycle of a cyclic pulse signal detected by the measuring sensor can be excluded and highly accurate measurement of torque is enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a method for non-contactly measuring changes in angle between an optical axis (a set of light emitting and light receiving fibers) and a slitted ring. , is used in the technical field of a method of correcting a torque measurement value using the above-mentioned angle measurement result.

BACKGROUND OF THE INVENTION A method of measuring the driving torque of a rotating shaft system using a conventional torque measuring device will be described with reference to FIG.

, l is a rotating part of the torque measuring device mounted on the rotating shaft, and is connected between the driving device 2 and the load device 30 via the driving shaft 4.

The inside of the rotating part 1 has a structure in which a slitted ring 7.8 is attached to both ends of the torsion shaft 6 that transmits torque, with slits provided at equal pitches on the circumference, which facilitates torque measurement. Therefore, one of the slit rings 8 is installed close to the other ring via the tube 10 on which no torque is applied. The two slit rings 7.8 are manufactured with the same external dimensions, number of slits, slit pitch, etc., and when assembled, both slits are installed with a slight shift in advance, so that the torsion shaft 6 is not twisted by the action of torque. When the torque is applied, the amount of deviation of the slit changes in proportion to the torque. A light emitting optical fiber 11 and a light receiving optical fiber 12 are supported and fixed from a place where they do not move, such as a foundation, so as to face each other across the slit portions of the two slit rings 7 and 8.

Reference numeral 13 denotes a calculation unit of the torque measuring device, which includes a high-frequency oscillator 14, a light emitting device 15 composed of an LED, etc., a photoelectric conversion device (converts an optical signal into an electrical signal) 16 composed of a photodiode, etc., and a torque measuring device. It is composed of a calculation device 17, and three display devices 18, 19, and 20 are connected to the output section of the torque calculation device 17.

The light emitting device 15 emits high frequency pulses modulated by the output of the high frequency oscillator 14, and transmits the light to the light emitting optical fiber 1.
1 to a light-receiving optical fiber 12. The light pulse signal received by the light receiving optical fiber 12 is transmitted to the photoelectric conversion device 16 and converted into an electric pulse signal. Because of the ring 7.8, the drive shaft 4
With the zero rotation, the optical signal is periodically interrupted, and the output of the photoelectric conversion device 16 becomes a series of burst signals in which high-frequency signals of the same frequency as that transmitted by the high-frequency oscillator 14 are periodically interrupted. .

By counting the number of high-frequency signals counted during a unit time (for example, 1 second), the torque T (kg, m) acting on the shaft system is calculated, and the torque T and shaft rotation speed N are calculated.
The output power P (KW) of the accumulating drive device 2 is calculated, and each result is displayed on three display devices 18, 19, and 20.

FIG. 4 shows an example in which input optical fibers 11 and 12 are placed opposite each other with the slit portion of the slit ring sandwiched therebetween. In the figure, dimension A (mm) represents the amount of deviation of the two slits in the circumferential direction.

In order to make it easier to understand the geometric shape between the optical fiber and the slit, FIG. 5 shows a diagram in which the slits arranged on the circumference are expanded on one axis. Symbols r, p, ノ, t in the figure,
w indicates the shape and dimensions (unit: mm) of the slit portions of the two slit rings 7.8. Optical fiber for transmitting and receiving light 1
2 and 12 are attached at right angles to the side surface of the slit ring, and assuming that the slit moves to the left in the figure at a circumferential velocity V (m/sec), the optical signal received by the optical fiber 12 is It will look like Figure 6.

In FIG. 6, Tl is the time (See) during which light is received from the light projecting optical fiber f-fly 1, and To is the time (Sec) of one cycle of the optical pulse signal periodically interrupted by the slit. ). When To and T are determined by considering the geometrical shape shown in Fig. 5, we obtain To=p/V(s
ee) (1) Tl=D-A)/V
(see) (2). Here, the amount of deviation l (m) of the slit is determined by the torque acting on the axis of one rotation! +Δl(m), and T1 also changes as TI+ΔT.

The amount of change in time ΔT is measured by the method of counting the number of high frequency signals mentioned above, and calculated into torque.

This method has the following drawbacks.

Now, in FIG. 5, the optical fiber 11.1 for transmitting and receiving light
The optical path formed by 2 is at an angle θ (rad
), the light reception time Tl is TI = (r
−l + w −tanθ)/V (3),
T1 changes not only by the change Δ in l due to the action of torque, but also by the inclination angle θ.1. If the angle θ between the optical axis and the rotating axis changes during torque measurement, a torque measurement error will occur.

Problems to be Solved by the Invention The present invention combines a conventional torque measurement sensor with a new angle measurement sensor to improve the mounting angle of a composite upper sensor (a set of input and light receiving optical fibers and two slit rings). The object of this invention is to automatically correct torque measurement errors due to changes and enable accurate torque measurement.

Means for Solving the Problems The present invention employs the following means in order to solve the above-mentioned problems. That is, the second light-emitting optical fiber and the light-receiving optical fiber are arranged opposite to each other by sandwiching one of the two slit rings or a slit ring separately attached coaxially to the rotating shaft. The inclination of the rotation axis is determined from the relationship between the time during which the light is transmitted through the slit and the time during which the light is blocked, and the amount of light transmitted through the light receiving optical fiber is corrected to measure the torque.

Function By combining a conventional torque measurement sensor with a new angle measurement sensor to create a composite sensor, the installation of the sensor (a set of optical fibers for transmitting and receiving light and two slit rings) detects angular changes using pulse waves. The torque calculation device that performs calculations corrects torque measurement errors due to the inclination between the optical axis and the slit ring caused by deformation and movement of the rotating shaft during torque measurement, and enables highly accurate torque measurement at all times.

Embodiments Next, embodiments of the present invention will be described in detail with reference to FIGS. 1 and 2.

FIG. 1 shows a system of measuring equipment for carrying out the torque measuring method of the present invention.

Reference numeral 2-20 is the same as the conventional example described above;
The radial length of the slit portion of one of the slit rings 7.8 is made longer than the other, and a pair of light emitting/receiving optical fibers 21.22 are connected to that portion.
The optical fibers 11 and 12 are installed as inclination angle measurement sensors in the same manner as the existing optical fibers 11 and 12 for light emission and light reception. It is assumed that the four optical fibers are fixed to the fixed part in such a way that their mutual positional relationship does not change during measurement.

The two light emitting optical fibers 11.21 are connected to the light emitting device 15. The two light receiving fibers 12.22 are connected to each photoelectric conversion device 16.26, and the output of the photoelectric conversion device 16.26 is connected to the torque calculation device 17.

As in the conventional case, the optical signal time Tl measured by the photoelectric conversion device 16 from the drive device 2 is as described above when the angle between the optical axis formed between the optical fibers 11 and 12 and the side surface of the slit ring is 90 degrees. Equation (2) becomes, and if there is a slope, (
3) Equation becomes.

The emitting/receiving optical fibers 21.22 and the extended slit portion of the slit ring 7 are sensors for measuring the above-mentioned tilt angle changes, and the optical axis formed by the emitting/receiving optical fibers 21.22 and the slit If the relationship of the ring 7 is shown in the same way as in FIG. 5, it will be as shown in FIG.
The optical signal received by the laser beam becomes a periodic pulse wave similar to that shown in FIG.

The time To of one cycle of the above periodic pulse wave is the same as equation (1), and the time T1 during which light is being received during the period is, if the mounting has an angle θ (rad), T'=(r-Tanθ)/V (Sea)
(4) becomes.

Equation (4) above is not affected by the relative displacement w (m) of the two slits due to the action of torque, and the dimensions (radius, thickness, slit pitch) determined by the geometric shape of the slit ring. If the axis of rotation is given, it is possible to back-calculate the slope θ from the time measurement value T' (Sea).

That is, by providing the torque calculation device 17 in FIG. 1 with the above calculation function, the inclination angle θ can be calculated.
The result is displayed on the device 18.19.20.
By displaying one of them, it is possible to know the inclination angle of the optical axis at the time of torque measurement, and it is also possible to reset it to the normal state (for example, 0 (rad)). As a result, it is possible to cancel the term of the influence of the inclination angle θ included in the light reception time T1 ((Equation 31)) in one cycle of the periodic pulse signal detected by the torque measurement sensor, and to obtain high-precision torque. Enables measurement.

Alternatively, the calculation result θ (rad) of the above tilt angle can be expressed as (3)
By substituting θ in the equation, it is also possible to correct the influence of the inclination angle (the torque calculation device 17 has a calculation function), allowing highly accurate torque measurement without re-correcting the sensor mounting angle. It is possible.

Next, as correction methods, there are two methods: (a method of moving the optical axis to the normal state using the measurement and calculation results of the al inclination angle, and a method of (b)
There is a method in which torque measurement data is corrected and calculated on software using the measurement and calculation results of the inclination angle.

Effects of the invention When the optical axis formed by the optical fibers 11 and 12 for transmitting and receiving light for torque measurement is not equilateral to the slit ring,
Although the inclination angle θ becomes a cause of torque measurement error, the measuring method of the present invention allows accurate torque measurement at all times.

[Brief explanation of drawings]

Figures 1 and 2 relate to the present invention; Figure 1 is a system diagram of the torque measuring device, Figure 2 is a developed view showing slits arranged on the circumference on one axis, and Figures 3 and onwards are Regarding the conventional example,
Figure 3 is a system diagram of an example in which drive torque is measured using a conventional torque measuring device, Figure 4 is a schematic diagram of an example in which optical fibers are placed opposite each other across the slit of a ring, and Figure 5 is a circumference diagram. FIG. 6 is a developed view temporarily showing the slits arranged above on one axis, and is a simplified diagram showing the optical signal received by the light receiving optical fiber. 2...Drive device, 3...Load device, 4...Drive shaft, 6@
・Torsion shaft, 7.8--ring with slit, 10
...Tube, 11.. Optical fiber for light emission, 12.. Optical fiber for light reception, 14.. High frequency oscillator, 15.. Light emitting device, 16.. Photoelectric conversion device, 17. Medium torque calculation device, 18, 19. .20...Display device, 21...Optical fiber for input, 22...Optical fiber for light reception, 26...
Photoelectric conversion device.

Claims (1)

[Claims] Two circular rings having slits provided at equal intervals on concentric circles are attached coaxially to two different points on the rotation axis, and optical fibers for light projection are placed facing each other with the same two circular rings with slits sandwiched between them. A method of exchanging light with a light-receiving optical fiber through the slit and measuring the torque acting on the rotating shaft from the amount of light transmitted through the light-receiving optical fiber, the method comprising: On the other hand, or alternatively, a second
A light emitting optical fiber and a light receiving optical fiber are arranged facing each other, and the inclination of the rotation axis is determined from the relationship between the time when the light is transmitted through the annular slit and the time when the light is blocked. A torque measurement method that measures torque by correcting the amount of light transmitted through the optical fiber.