JPS60195430A - Torque detecting device - Google Patents

Abstract

PURPOSE:To execute a non-contact detection of a torque by constituting a self- oscillating circuit by winding a detecting coil at a gap to a magnetic layer stuck to the outside periphery of a driven shaft, and detecting a variation of magnetic permeability by a torque as an oscillation frequency of its circuit. CONSTITUTION:Plural slender magnetic layers 5 are stuck at an angle of 45 deg. against the axial direction, to the outside periphery of a driven shaft 1, a pair of detecting coils 7a, 7b are wound to the shaft 1 so as to surround the layer 5 through a coil bobbin 6 made of a non-magnetic material of a prescribed interval, and a self-oscillating circuit 8 in which the shaft 1 is a magnetic core is constituted. Also, the circuit 8 is constituted of transistors 9, 10, coupling resistances 11, 12, coupling capacitors 13, 14, etc., the coils 7a, 7b are used as a collector winding of the circuit 8, a driving power source VCC is supplied, and a collector voltage V0 of the transistors 9, 10 is fetched as an output. In this way, a variation of an oscillation frequency of the circuit 8, which is generated by a variation of magnetic permeability of the layer 5 in case when a torque is impressed can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a torque detection device that non-contactly measures the shaft torque of a passive shaft such as a rotating shaft.

[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 with 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 shaft has the disadvantage that accuracy depends on whether or not the strain gauge is attached properly, and in addition, it is necessary to attach a slip ring, telemeter, etc. from which the output signal is taken, making the device large. In addition, there are drawbacks such as high-speed rotation and long-time operation t' (the electrical resistance 1+i of the slip ring changes and noise is likely to occur.The method for detecting the phase difference due to the twisting of the intermediate shaft is , the electrical circuit is complicated and expensive, and it is difficult to detect both high-speed rotation and low-speed 101 rotation of the rotating shaft.The method of utilizing the magnetostrictive effect using a magnetic material shaft is There is an advantage to having a real shaft available, but on the other hand, a lot of attention is paid to the strength of regular shafts.

Not much consideration was given to magnetic properties.

Magnetically it is extremely non-uniform. Therefore, the output has a rotation angle dependence due to the magnetic non-uniformity of this shaft, that is, there is a draft of the output as the shaft rotates.

In other words, it has the disadvantage that the output varies depending on the rotation angle. Of course, this output fluctuation can be corrected by providing a plurality of detectors around the axis, but the structure becomes more complicated and this is not a preferable method.

[Summary of the invention]

This invention was made in order to eliminate the drawbacks of the conventional device as described above.
A plurality of elongated magnetic layers are fixed at an angle of 5 degrees, a detection coil is wound around the magnetic layer with a predetermined gap from the passive shaft, and the detection coil is used to connect the magnetic layer to the magnetic core. By configuring a self-excited oscillator circuit, and detecting a change in the oscillation frequency of the oscillation circuit caused by a change in permeability of the magnetic layer when torque is applied.

The present invention provides a torque detection device that can detect the magnitude and direction of applied torque in a non-contact manner.

[Embodiments of the invention]

FIG. 1 is a diagram for explaining the operating principle of this invention. It is generally well known that when stress is applied to a magnetic material, its magnetic properties change; tensile stress increases magnetic permeability, and compressive stress decreases magnetic permeability. By the way, as shown in Fig. 1, when torque T is applied to the passive shaft (11), stress σ is generated in the direction of ±45° with respect to the central axis (2).In other words, it has an angle of +45° with respect to the central axis (2). Tensile stress σ is generated on the line, and compressive stress -σ is generated on the line with an angle of -45°. Therefore, a magnetic layer made of a high magnetostrictive material is fixed to the outer periphery of the passive shaft (1), and when torque is applied. If you use the magnetostrictive effect of
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FIG. 2 is a structural diagram showing an embodiment of the present invention. f1
1f'i Center 4411 +21 A passive shaft such as a rotating shaft (hereinafter referred to as a rotating shaft) is bent, and the bearing (3
).

It is rotatably supported by (4). This rotation axis +
11 shall have sufficient mechanical strength to withstand torque. (5) is a plurality of elongated magnetic layers made of a highly magnetostrictive material, and is fixed to the outer periphery of the passive shaft (1) at an angle of 45° with respect to the axial direction. This magnetic layer (5
) is preferably a soft magnetic amorphous metal. This is because amorphous metals are obtained in the form of thin sheets, have high magnetostrictive properties, and also have excellent mechanical strength.

(6) is provided at a predetermined distance from the outer periphery of the passive shaft i11. It is a cylindrical coil bobbin having the same central axis as the passive 1lbf+1, and is made of non-magnetic material. (
7a) and (7b) are a pair of detection coils that are wound around the passive shaft [11] via a coil bobbin +a+ so as to completely surround the magnetic layer (5).

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

This electric circuit consists of the passive 11+ f+ in FIG.
It is for converting the torque applied to 1 into an electrical signal, and was constructed using detection coils (7a) and (7b). This is a self-excited oscillator circuit (8) with a magnetic core fixed to a passive shaft (11) to which a magnetic layer (5) is fixed. In this embodiment, it is constructed of a well-known resistor-capacitor coupled inverter, a so-called magnetic multivibrator. +t91+
un is a transistor, 0υ and uz are coupling resistances.

03, H is the coupling capacitor, as, be is the resistance +v
QQ is a drive power supply and +vO is an output signal. Now, the oscillation circuit (8) uses the passive shaft (1) to which the magnetic layer (5) is fixed as a magnetic core, and the detection coils (7a) and (7b) surrounding the magnetic layer (5) are used as the oscillation circuit. Since the structure is such that it is provided as the collector winding of the oscillation circuit (8), the transistor +91. [The conduction time of 1G is mainly determined by the inductance of the collector winding and constants of the transistor, etc., and it is the time from when the transistor is ONL until the collector current gradually increases and reaches a value that cannot maintain the saturation of the transistor. Become. By the way, if the magnetic permeability of the magnetic core changes, the inductance of the collector winding changes in proportion to it, so the conduction time also changes in accordance with the change. Therefore, if the collector voltage vo of the transistor (9) or 01 of the oscillation circuit (8) is taken out as the output, this change can be calculated as a change in one oscillation frequency.
It's a hailstorm. now.

When a torque is applied in the direction shown in Figure 2, the magnetic layer (5) fixed at 45 degrees with respect to the central axis (2) has a sufficiently elongated shape, so that only tensile stress is applied. As a result, its magnetic permeability increases. Therefore, the detection coil (7a)
, (7b) increases, and the oscillation frequency of the 9 oscillation circuit becomes lower. When a torque is applied in the opposite direction, the magnetic layer (5) is now subjected to compressive stress.

Since its magnetic permeability decreases, the detection coil (7a), (7
The inductance of b) decreases, and the 1 oscillation frequency becomes high (
Become. Needless to say, this change in oscillation frequency is proportional to the magnitude of the applied torque, so by detecting this frequency change, the magnitude of the applied torque can be detected. Detection of this frequency change is not shown in the figure, but it goes without saying that it can be easily detected using a well-known frequency-voltage converter.

〔Effect of the invention〕

As described above, according to the present invention, on the outer periphery of the passive shaft.

Self-excited oscillation using multiple elongated magnetic layers fixed at an angle of 45° with respect to the central axis and a detection coil wound around them with a predetermined gap. The passive shaft itself is used as the feedback element of the oscillation circuit.

Torque is detected by detecting the change in magnetic permeability of the magnetic layer that occurs when torque is applied as a change in the oscillation frequency of the output signal of the oscillation circuit, so the torque is detected in both the static and rotating directions without contact. It has the effect that it can be detected including Furthermore, since the detection coil is wound rotationally symmetrically around the shaft, the output has no dependence on the rotation angle of the shaft.

In addition, the detection portion only requires a magnetic layer and two detection coils surrounding the magnetic layer, resulting in a simple configuration.

[Brief Description of the 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 an embodiment of the present invention. Figure 3 is a schematic electrical diagram of the same. In Figure 1, (1) is the passive shaft, (5) is the magnetic layer, and (7a) and (7b) are the detection coils. (8) is a self-excited oscillation circuit. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent Masuo Oiwa (and 2 others) Figure 2

Claims (1)

[Scope of Claims] (1) On the outer periphery of the passive shaft that receives torque, a plurality of elongated magnetic layers (magnetic layers) are formed on the passive shaft so as to surround this magnetic layer. It was constructed using a detection coil wound with a predetermined gap between the two.It was equipped with a self-excited oscillation circuit whose magnetic core was a passive shaft to which a magnetic layer was fixed, and A torque detection device characterized in that a change in magnetic permeability of a magnetic layer is detected as an oscillation frequency of an oscillation circuit. A torque detection device according to claim 1fA, characterized in that the resistance-coupled inverter [consists of four paths]. Torque detection device according to scope 1.