JPH0295228A - Torque sensor - Google Patents

Abstract

PURPOSE:To prevent the generation of a twist, etc., on an amorphous alloy at the bonding process and to improve a symmetrical character for the output of a torque sensor to the torque by sticking along a groove the amorphous alloy having a magnetostriction with a width smaller than that of the groove with a certain depth formed on a shaft surface over the entire circumference. CONSTITUTION:The groove 1a with a fixed depth is formed on the surface of the shaft 1 perpendicularly to the longitudinal direction over the entire circumference, and the amorphous alloy 2 having the magnetostriction with the width smaller than that of the groove 1a within a specified tolerance is fitted-in along the groove 1a and bonded. A basic construction having a coil 4 arranged at the outside of the shaft 1 in a concentric circular state to the shaft 1 through a constant gap is provided on at least one or more places. Then, with the torque conveyed to the shaft 1, the change of a strain generated on the surface of the shaft 1 is converted to the change of magnetic permeability by a reversed magnetostrictive effect of the amorphous alloy 2 and measured as the change of a self-inductance for the coil 4, then the torque is detected. With this arrangement, the generation of the twist on the amorphous alloy 2 at the bonding and the possibility of that the output is asymmetric to the applied torque are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a torque sensor that can detect torque transmitted to a shaft in a non-contact manner by applying the inverse magnetostrictive effect of an amorphous material.

BACKGROUND OF THE INVENTION Conventionally, it has often been done to convert the strain that occurs when an external force is applied to a change in magnetic permeability using a material whose magnetic properties change due to the strain, and to detect this as a change in the inductance of a coil. for example.

The torque sensor disclosed in Japanese Unexamined Patent Publication No. 59-163143 is an example of this. The torque sensor has a structure as shown in FIG. 11 in the figure is the axis.

12 is an amorphous alloy having magnetostriction bonded to the shaft surface, and 13 is a coil disposed outside the amorphous alloy. Axis 11
When torque is transmitted to the amorphous alloy 12, distortion occurs on its surface, and the amorphous alloy 12 is also distorted. The magnetic permeability changes due to the reverse effect of magnetostriction, and the inductance of the coil 13 changes. This change is measured by a detection circuit to detect torque.

Problems to be Solved by the Invention However, in the torque sensor configured as described above, the amorphous alloy is adhesively fixed to the shaft, but the amorphous alloy tends to be twisted or the adhesive position shifts during the adhesive process, and this causes the output torque of the torque sensor to decrease. The problem was that the symmetry was poor.

The present invention aims to solve the problems of such conventional torque sensors.

Means for Solving the Problems The present invention forms a groove with a constant depth on the shaft surface at right angles to the longitudinal direction over the entire circumference, and creates magnetostriction with a width smaller than the width of the groove within a predetermined tolerance. The basic structure has at least one basic structure in which an amorphous alloy having an amorphous alloy is fitted and bonded along the groove, and a coil is arranged concentrically with the shaft with a certain gap on the outside thereof, and the shaft surface is caused by the torque transmitted to the rotating shaft. The change in strain that occurs in the amorphous magnetic alloy is converted into a change in magnetic permeability by the inverse magnetostriction effect of the amorphous magnetic alloy, and this is measured as a change in the self-inductance of the coil to detect torque.

Function The present invention forms a groove of a constant depth on the shaft surface at right angles to the longitudinal direction over the entire circumference, and forms an amorphous alloy having a magnetostriction width smaller than the width of the groove within a predetermined tolerance on the surface. By fitting and bonding along the grooves, it is possible to prevent the amorphous alloy from twisting during the bonding process, and improve the symmetry of the torque sensor output with respect to torque.

Example Embodiments of the present invention will be described below based on the drawings.

Embodiment 1 FIG. 1 is a partially cutaway structural diagram of a main body of a torque sensor in an embodiment of the present invention. In the figure, 1 is the axis. The material is titanium, and the shaft diameter is 35 mm. la is a groove formed perpendicular to the longitudinal direction of the shaft and has a width of 35 mm, Q mm,
The shaft diameter of the groove 1a having a depth of 1 mm is 33 mm. Amorphous alloy 2 is Fe-Cr-5i-8
It was manufactured using the ultra-quenched single roll method with the following composition. The thickness is 20-3
0um, magnetostriction constant 22X10-6 saturation magnetization 1.13 (Tesla), coefficient of thermal expansion? , 8×10 −6 (1,/° C.). Amorphous alloy 2 has a width of 34 mm due to etching.
The width of the groove 1a was 8 mm, which was 0.2 m tn narrower than the width of the groove 1a. Further, the length of the amorphous alloy 2 was set to 1100 tn, which is approximately the circumference of the groove portion. After that, heat treatment is performed at a temperature higher than the Curie temperature and lower than the crystallization temperature, and the shaft diameter of the groove 1a is 3.
The winding pattern was the same as that of 3tnm, and it was glued into the groove 1a.

Adhesion is bismaleimide triazine resin BT2164
(manufactured by Sanjo Gas Chemical Co., Ltd.) in the air at 180°C for 3 hours, and then annealed at 250°C for another 2 hours.

A Teflon bobbin 3 is arranged concentrically with the shaft 1, and a coil 4 is wound around it. 4a is connected to the detection circuit at the end of the coil.

FIG. 2 shows the output of the torque sensor. The horizontal axis is applied torque, and the vertical axis is torque sensor output voltage. The solid line in the figure is the torque sensor output according to the present invention, and the broken line is the conventional torque sensor output. As is clear from the figure, in the conventional torque sensor, the amorphous alloy is twisted during adhesion and the output is asymmetrical with respect to the applied torque, whereas the torque sensor of the present invention shows an output that is symmetrical with respect to the applied torque. .

In the torque sensor configured as described above, a case has been described in which the width of the amorphous layer is 0.2 mm smaller than the width of the groove 1a, but this may change depending on the shaft diameter and width of the groove 1a portion. As a result of detailed study, it has been confirmed that when the shaft diameter of the groove 1a is in the range of 10 mm to 130 mm, the same effect can be achieved as long as the tolerance is 2% or less of the groove width. 2%
If it exceeds this, misalignment occurs and the effect of forming the groove is lost. Similar effects can be expected for other shaft diameters as long as the width has a tolerance of 2% or less.

Furthermore, although the depth of the groove was described as 1 mm, it has been confirmed that the same effect can be obtained if the depth is equal to or greater than the thickness of the amorphous material.

Embodiment 2 FIG. 3 is a partially cutaway structural diagram of a torque sensor according to a second embodiment of the present invention. In the figure, the same parts as those in the first embodiment are given the same numbers, and the explanation will be omitted.

In the figure, 1 is a shaft with a thicker shaft diameter at the center.

Fillers 1a are formed at two places in the thickened part.

2a and 2b are amorphous alloys. Slits are formed in the amorphous alloy by etching at 45° and 145° with respect to the longitudinal direction of the shaft.

5 is a ball hair ring, which is attached to both ends of the thick part of the shaft 1. Reference numeral 6 denotes a magnetic yoke made of 45% Ni--Fe alloy, which together with the coil 4 and the amorphous alloys 2a and 2b constitutes a magnetic circuit. The magnetic yoke 6 is rotatably attached to the shaft 1 by a ball bearing 5.

The width tolerance of the groove 1a and the amorphous alloys 2a and 2b, the bonding method, etc. are all the same as in the first embodiment.

In the torque sensor having this configuration, when ten torques are applied to the axis l, the magnetic permeability of the amorphous alloy 2a increases, and that of the amorphous alloy 2b decreases. By detecting the difference between the magnetic permeability changes of 2a and 2h, the direction and magnitude of the torque can be detected at the same time.

FIG. 4 shows the output of the torque sensor according to the present invention. In the figure, the horizontal axis is the torque, and the vertical axis is the output voltage of the torque sensor.

The solid line in the figure is the output of the torque sensor according to the present invention. The broken line is the output of a conventional torque sensor in which the shaft 1 is not provided with a groove. The torque sensor according to the present invention has greatly improved symmetry with respect to torque.

Furthermore, even when the torque sensor is used in an environment with temperature changes, it has been confirmed that the torque sensor according to the present invention does not cause zero tripping and exhibits a good output.

Embodiment 3 FIG. 5 is a partially cutaway structural diagram of a torque sensor according to a third embodiment of the present invention. Components in the figure that are the same as those in the second embodiment are designated by the same reference numerals, and explanations thereof will be omitted. 7 is bismaleimide triazine resin (Mitsubishi Gas Chemical Co., Ltd. B)
The periphery of the amorphous alloys 1a and 1b bonded to the groove 1a is molded with resin using T2160).

Conventional torque sensors have been difficult to mold with resin because the amorphous alloy bonded part does not have a groove. In the torque sensor of the present invention, as shown in FIG. 6, a Teflon hollow cylindrical container 9 is tightly fitted onto the shaft l so as to cover the groove 1a, and resin is poured through a hole 9a previously provided in the hollow cylindrical container 9. A resin mold 7 was formed by pouring and then heat treatment. By adopting such a configuration, the symmetry of the output of the torque sensor can be improved, and the adhesive strength of the amorphous alloy is also improved, which greatly improves the durability.

Embodiment 4 FIG. 7 is a partially cutaway structural diagram of a torque sensor according to a fourth embodiment of the present invention. Components in the figure that are the same as those in the second embodiment are designated by the same reference numerals, and explanations thereof will be omitted. 8 is a Teflon heat-shrinkable tube (manufactured by Gunze Co., Ltd.) and is an amorphous alloy 2a.

I use it as a tightening jig when gluing 2b. After adhesion, it is used as it is as a protective film for the amorphous alloys 2a and 2b. In the conventional configuration, when the shrink tube contracts, the amorphous alloys 2a and 2b are displaced or twisted, resulting in poor output symmetry, but in the torque sensor of the present invention, the amorphous alloys 2a and 2b are formed in the groove 13.
Because they are fitted and glued together, a torque sensor can be constructed that does not cause twisting and has a symmetrical output with respect to torque.

By using a heat-shrinkable tube in this manner, moisture resistance and chemical resistance can also be greatly improved.

As is clear from the detailed description of the invention, the present invention not only greatly improves the symmetry of the output of the torque sensor with respect to the torque, but also facilitates the formation of resin molds and protective films, and improves the durability of the torque sensor. properties and chemical resistance can be greatly improved.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway structural diagram showing the structure of the torque sensor in the first embodiment of the present invention, FIG. 2 is a graph of the output of the torque sensor in the same embodiment, and FIG.
A partially cutaway structural diagram of the torque sensor in the example, FIG. 3 is a graph of the output of the torque sensor in the example,
FIG. 4 is a partially cutaway structural diagram of a torque sensor according to a third embodiment of the present invention, FIG. 5 is a partially cutaway structural diagram of a torque sensor according to a third embodiment of the present invention, and FIG. 6 is a partially cutaway structural diagram of a torque sensor according to a third embodiment of the present invention. FIG. 7 is a partially cutaway diagram showing the resin molding method of the torque sensor in the example, FIG. 7 is a partially cutaway structural diagram of the torque sensor in the fourth embodiment of the present invention, and FIG. 8 is a partially cutaway diagram showing the torque sensor of the conventional example. It is a partially cutaway perspective view shown. l...shaft, 1a...groove formed in the shaft, 2.2a, 2
b...Amorphous alloy, 3...Bobbin, 4...
Coil, 4a... Coil end, 5... Ball bearing, 6... Magnetic caulk, 7... Resin mold, 8...
・Heat shrink tube 7.9 ・Teflon hollow cylinder, 9
a... Hole provided in Teflon hollow cylinder 9, 11...
Shaft, 12...Amorphous alloy, 13...Coil Agent's name Patent attorney Shigetaka Awano Haka 1 famous confectionery figure 1 20Kgfm 20 gfm Figure 4 Figure 6

Claims (4)

[Claims] (1) A groove with a constant depth is formed on the shaft surface at right angles to the longitudinal direction over the entire circumference, and an amorphous alloy having magnetostriction with a width smaller than the width of the groove within a predetermined tolerance is formed along the groove. At least one basic structure is provided in which a coil is disposed concentrically with the shaft with a certain gap in between, and the change in strain generated on the shaft surface due to the torque transmitted to the rotating shaft is as described above. A torque sensor characterized in that the inverse magnetostrictive effect of an amorphous magnetic alloy is converted into a change in magnetic permeability, and this is measured as a change in self-inductance of the coil to detect torque. (2) The torque sensor according to claim 1, wherein the difference between the width of the amorphous alloy and the width of the groove is 2% or less of the width of the groove. (3) The torque sensor according to claim 1, wherein the outer surface of the amorphous alloy is molded with resin. (4) The torque sensor according to claim 1, wherein the amorphous alloy is covered with a heat-shrinkable tube.