JPS60173433A - Torque detector - Google Patents

Abstract

PURPOSE:To detect torque without reference to ambient temperature by sticking two magnetic layers on the outer periphery of a passive shaft, constituting an oscillation circuit by use of a detection coil wound around it, and detecting the torque as a difference in duty ratio variation. CONSTITUTION:The 1st and the 2nd magnetic layers 5 and 6 made of high magnetostrictive materials are made magnetically anisotropic at +45 deg. and -45 deg. from a center axis 2. The 1st and the 2nd detection coils 8 and 9 are wound around the rotating shaft 1 through a coil bobbin 7 while covering the magnetic layers 5 and 6. Transistors (TR) 14 and 15 of a resistance coupling type inverter vary in conduction time with the magnetic permeability of a magnetic core because the inductance of a collector winding as the magnetic permeability of the magnetic core varies. Therefore, the duty ratio varies according to relative variation in the magnetic permeability of the magnetic layers 5 and 6 as magnetic cores of detection coils 8 and 9. Consequently, the value and direction of the applied torque are detected without the influence of bending stress nor the influence of variation in ambient temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a torque detection device for measuring a passive shaft, such as a rotary shaft, in a non-contact manner.

[Prior art]

Conventionally, methods for measuring the axial torque of a passive shaft, such as a rotating shaft, include a method in which a strain gauge is attached to the rotating shaft and the torque is detected by a change in resistance value of the strain gauge caused by twisting of the shaft due to torque. A method in which an intermediate shaft having a Young's modulus is inserted between the drive side and the load side, and the torsion of the intermediate shaft is detected as a phase difference, and the magnetic permeability of the magnetic material shaft, that is, the rotating shaft, changes due to external force or torque. There are methods that utilize the so-called magnetostrictive effect. The method of attaching the strain gauge to the rotating shaft has the disadvantage that the strength of the strain gauge depends on the quality of attachment of the strain gauge. It is necessary to attach a slip ring, telemeter, etc., which increases the size of the device. In addition, there is a drawback that when rotating at high speed and operating for a long time, the electrical resistance value of the 71 knob ring changes and noise is likely to be generated. The method of detecting the phase difference due to the torsion of the intermediate shaft is equivalent because the electric circuit is complicated, and there is also a disadvantage that it is difficult to detect both high-speed rotation and low-speed rotation of the rotating shaft. . How to utilize the magnetostrictive effect using a magnetic material shaft.

The starting point is that a real axis can be used, but -
In general, most attention is paid to the strength of ordinary shafts, and little consideration is given to the magnetic properties, so that they are highly non-uniform magnetically. Therefore, the output has a rotation angle dependence due to the magnetic non-uniformity of this axis, that is, there is a drift in the output as the axis rotates, in other words, I! It has the disadvantage that the output fluctuates depending on the rotation angle. Of course, this output drift or output fluctuation can be corrected by providing a plurality of detectors around -11, but the structure becomes more complicated and this is not a preferable method. In addition, many of these methods cause errors due to bending stress and changes in material properties due to changes in ambient temperature, and in adverse environments such as environments with vibration,
The disadvantage is that it is difficult to use at high or low temperatures.

[Summary of the invention]

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and consists of fixing two magnetic layers around the outer periphery of a passive shaft, and forming a trough (which surrounds each magnetic layer). Two detection coils are wound rotationally symmetrically around the passive shaft, and a self-excited push-pull oscillator circuit is constructed using these valley/detection coils, and the passive M itself with each magnetic layer is used as the magnetic core of the circuit. By using this as a feedback element, the applied torque can be determined by detecting the difference in the duty ratio change of the pair of oscillation signals from the oscillation circuit caused by the change in magnetic permeability of each of the magnetic layers at the time of torque impression. The aim is to detect the magnitude and direction without being influenced by bending stress or ambient temperature.

[Embodiments of the invention]

FIG. 1 is a diagram for explaining the operating principle of the present invention. It is generally well known that when stress is applied to a pillar material, its magnetic properties change.

Tensile stress increases magnetic permeability, and compressive stress decreases magnetic permeability. By the way, when torque T is applied to the passive shaft (1) as shown in Fig. 1, +
Stress σ is generated in the 45° direction. Toe p center 1lIIIJ
A tensile stress σ occurs on a line having an angle of +45° with respect to (2), and a compressive stress −0 occurs on a line having an angle of −45°. Therefore, receive! I! Torque can be detected by fixing a magnetic layer made of a high magnetostrictive material to the outer periphery of the Ill14II (1) and utilizing the strain effect when torque is applied.

FIG. 2 is a block diagram showing an embodiment of the present invention, (1
) is a passive shaft such as a rotating shaft (hereinafter referred to as a rotating shaft) having a central axis (2), and a bearing (3).

(4) The cuff is rotatably supported. 7. This rotating shaft (1) shall have sufficient mechanical strength to withstand torque. +5+, +6) are the first and second magnetic layers made of heavy positive material, and the first magnetic layer (5) has magnetic anisotropy in the +45° direction with respect to the central axis (2). The amphoteric layer (6) of No. 2 is given magnetic anisotropy in the -450 direction.

A solid layer is formed on the outer periphery of each passive 11QIIf+l. Each of these magnetic layers +51. (As for the magnetic axis forming 61, one that is soft magnetic and has high magnetostriction characteristics is mt L<
, amorphous metals are preferred. This is because amorphous metals have similar magnetostrictive properties and excellent mechanical strength. (7) is a cylindrical coil bobbin made of a non-magnetic material having the same central axis as the rotation axis fi+, and (8) is the above-mentioned first O.
A first detection coil (9) is wound around the outer periphery of the rotating shaft (1) via a coil bobbin (7) so as to surround the IT layer (5). The coil bobbin is a second detection coil that is wound around the outer periphery of the rotating shaft (1) via force so as to surround the coil bobbin.

FIG. 3 is an electrical circuit diagram showing one embodiment of the present invention.

This electric circuit is for converting the torque applied to the rotating shaft fl in FIG. 2 into an electric signal and deriving it. This is a self-excited push-pull type oscillation circuit whose magnetic core is a rotating shaft fil on which +6+ is solidified, and in this embodiment, it is constituted by a well-known resistance coupling type inverter circuit. (141, as is the transistor, 'ae, αD, α, Ql is the coupling resistance I C11l
) #off) is a coupling capacitor, and Vcc is a drive power supply.

Now, as a magnetic core used in a resistance-coupled inverter circuit, the rotating shaft (1) itself to which the first and second magnetic layers (51, (61) are fixed is used; 5), (The first and second detection coils +81.+91 surrounding 61 are respectively utilized as collector windings of the oscillation circuit. Note that each of these detection coils +81.+91 is used as a collector winding of an oscillation circuit.
+91 is a coil bobbin (
7). In the trough 2 fufu 0 station of a resistive coupled inverter, the two equally suitable times change when the magnetic permeability of the core changes.

Because the inductance of the collector winding changes.

It changes depending on the change in its magnetic permeability. Therefore, the duty ratio changes depending on the relative change in the magnetic permeability of the magnetic layers (5) and (6) that form the magnetic core of the detection coil tel, (91).
), Q! 9 respective collector voltage ■C1t vc
2 is.

In principle, this is a rectangular wave signal with a level approximately twice that of the power supply voltage Vcc, but each collector output voltage VC1*
Vc2 is input to a waveform shaping circuit 0υ consisting of resistors '2Ln, QL (2F9) and operational amplifier 01. (c).

Rectangular wave signal V4. limited by power supply voltage Vcc. V2
formatted into. Note that this waveform shaping circuit aυ is constructed using an operational amplifier e4+ (g), and also serves as a buffer. Now, each of the waveform-shaped rectangular wave signals v1. v2 is the resistor and capacitor (c)
, an integrating circuit a2 consisting of a resistor (c) and a capacitor (c)
The DC level signal V that is input to the
It is converted to s+V4 and inputted to the primary stage differential amplifier circuit QIK. The differential amplifier circuit a is a resistor (to).

The above DC level is configured by OI), (c), a) and an operational amplifier (g), and is input to the negative phase input terminal and positive phase input terminal of the operational amplifier (to) via the resistor (to) and Cl11. signal v6. The differential voltage of v4 is amplified with a gain determined by the resistors (to) and (to) and is output.

FIG. 4 is a trough output waveform diagram for explaining the operation of the above embodiment. When no torque is applied to the rotating shaft +11, the magnetic permeability of the first and second magnetic layers +51.161 is equal, so the collector voltage vc1. (2) In principle, c2 becomes a signal with a duty ratio of 50%. Therefore, the signal v3. which is converted to a DC level. The voltage values of v4 are both V
OCl2 Tona9. Differential amplifier circuit (13 output voltage Vo
indicates zero and Seattleku zero. Next, consider a state in which torque is applied to the rotating shaft (1). As mentioned above, the first and second magnetic layers (5) and +6+ fixed on the outer periphery of the shaft (1) have magnetic anisotropy of 10,000 times the central axis (2) of the shaft (1).
in the +45° direction.

Since the other direction is applied in the -45° direction, when torque is applied to the axis (1), the respective magnetic layers +51. At +61, stress is applied that changes the magnetic permeability in the opposite direction.

In other words, at 10,000 yen, the magnetic permeability increases due to tensile stress.

On the other hand, compressive stress reduces the magnetic permeability. Therefore, the duty ratio of the signal of the oscillation circuit changes. (A) and (B) in Figure 4 are waveforms when the magnetic permeability of the first magnetic layer (5) increases and the magnetic permeability of the second magnetic layer (6) decreases due to the application of torque. Signal v1 after shaping. v2, (C), (D) is the DC level signal V3.v4 after they are integrated, @) is the v3.v4. (2) The output signal Vo of the differential amplifier circuit a with input 4 is shown. In the above case, the integrated DC level signal v3 is smaller than VOCl2, and v4 is smaller than VOCl2.
Since the output signal of the differential amplifier circuit 0:1 becomes larger, the output signal V of the differential amplifier circuit 0:1
Q indicates a positive value (FIG. 4(k) loss of consciousness).

If the torque is in the opposite direction to the above case.

Since the magnetic permeability of the magnetic layers +5+ and +6+ changes in the opposite way to the above case, the DC level signal v5 after integration is VO
Thicker than Cl2, ■4 is Vcc /2.1: , ri
Since smaller < fZ, the output signal Vo of the differential amplifier circuit θ
is negative 1 (Figure 4 (g)) broken line). As described above, the output signal vO of the differential width narrowing circuit is a voltage proportional to the torque as shown in FIG. It can be determined by the positive or negative of the voltage VD. Also, depending on the usage conditions, bending stress may be applied to the rotating shaft (11) in addition to screw stress due to time and L7, but this is also due to changes in the magnetic permeability of the columnar layer. However, in the configuration of the present invention, this bending stress is applied to the first and second magnetic layers in the same way, so the bending stress is applied to the first and second magnetic layers. (6
) for each magnetic layer +51
．． The direction is the same at f6+, so the differential amplifier circuit 0
3, their influences cancel each other out, and only the signal due to the torque is included in the output signal vo. In addition, the change in the characteristics of the magnetic Ja due to changes in the ambient temperature and the change in the characteristics of the two circuit elements also differ m
Since an amplifier circuit is used, they are also canceled out.

Note that in the above embodiment, two magnetic layers fixed to the 9 rotating shafts +
51. (6) were fixed with magnetic anisotropy at an angle of +45° with respect to the central axis of the shaft, but as shown in FIG. The same effect can be achieved by fixing them to the outer circumference of the shaft at an angle of +45° with respect to the central axis of the shaft in some cases, and at an angle of -45° with respect to the central axis of the shaft on the other hand. Shaft surface where stress and compressive stress are maximum +4
If the magnetic layer fixed in the 5° direction has a sufficiently elongated shape, when torque is applied to 4tl+, -
This is because one magnetic layer receives almost only tensile stress, and the other magnetic layer receives almost only compressive stress, and both magnetic column layers undergo changes in magnetic permeability similar to those in the above embodiment. Further, in the above description, the case where the passive shaft is a rotary shaft has been described, but it goes without saying that the passive shaft is not limited to nine rotary shafts.

〔Effect of the invention〕

As described above, according to the present invention, the first and second magnetic layers having magnetic anisotropy in different directions are firmly fixed to the outer periphery of the passive shaft, and a predetermined gap is formed in the passive shaft so as to surround them. A self-excited push-pull oscillation circuit is constructed using the first and second detection coils wound at the The torque is detected by detecting the change in magnetic permeability as the difference in the duty ratio change of each output signal of the Bunyupuru type oscillation circuit.

The present invention has the advantage that torque can be detected both in a stationary state and in rotation, including its direction, in a non-contact state, and the torque can be detected without being affected by bending stress or changes in ambient temperature. Furthermore, since the detection coil is wound rotationally symmetrically around the passive shaft, there is an effect that the output can be detected without dependence on the rotation angle of the shaft. Furthermore, the detection part consists of a magnetic layer and a detection coil surrounding it,
Another advantage is that its structure is very simple0

[Brief explanation of drawings]

Figure 1 is a diagram for explaining the operating principle of this invention, Figure 2 is a diagram for explaining the operating principle of this invention.
The figure is a structural diagram showing one embodiment of this invention. FIG. 3 is an electric circuit diagram thereof, FIG. 4 is a waveform diagram of a trough part for explaining the operation of FIG. 3, and FIG. 5 is a structural diagram showing another embodiment of the present invention. (1) is a passive axis,
(51, +61 are the first and second magnetic layers. +81. +91 are the first and second detection coils, (l
[I is a resistive coupled current inverter circuit that is a self-excited push-pull type oscillator circuit, a1) is a waveform shaping circuit, az is an integrating circuit, and a zero (to) differential amplifier circuit, C37), C381
is a magnetic layer made of elongated magnetic material. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent Masuo Oiwa (2 people) Figure 1 I Figure 2 - S++r Figure 4 514 3β 37

Claims (4)

[Claims] (1) First and second magnetic layers fixed on the outer periphery of the passive shaft that receives torque in different directions and having magnetic anisotropy of 45° with respect to the axial direction, each of these magnetic layers The first and second detection coils are wound around the passive shaft with a predetermined gap therebetween, and each of these detection coils is used. Equipped with a self-excited push-pull type oscillation circuit whose magnetic core is a passive shaft made of each of the above magnetic layers. A torque detection device characterized in that a change in magnetic permeability of the magnetic layer due to torque is detected as a difference in a change in duty ratio of a pair of output signals output from the oscillation circuit. (2) The torque detection device according to claim 1, wherein the self-excited push-pull oscillation circuit comprises a resistance-coupled inverter circuit in which each detection coil is a collector winding. (3) The magnetic layer according to claim 1, wherein each magnetic layer is made of an elongated magnetic material fixed on the outer periphery of the passive shaft in different directions and at an angle of 45° with respect to the axial direction. Torque detection device. (4) The torque detection device according to claims 1 and 3, wherein each magnetic layer is made of a soft magnetic amorphous metal.