JPH02102427A - Torque measuring instrument - Google Patents

Abstract

PURPOSE:To improve the sensitivity of measurement of torque by putting a coil in a core and arranging the opening end surface of the core in opposition to the end surface of a large-diameter part where a magnetic anisotropic part is formed. CONSTITUTION:Large-diameter parts 22 and 23 are formed at axial parts of a torque transmission shaft 21. Magnetic anisotropic parts 24 and 25 which have angles to the axial direction of the transmission shaft 21 are formed on the outer peripheral surfaces of the large-diameter parts 22 and 23 and coils 37 and 38 which can detect variations in magnetic permeability of the magnetic anisotropic parts 24 and 25 are arranged at the peripheries of the magnetic anisotropic parts. The coils 37 and 38 are put in the cores 29 and 30 made of ferromagnetic bodies in a C-sectioned annular shape. The opening end surfaces of the cores 29 and 30 are arranged in facing of the end surfaces of the large-diameter parts 22 and 23. Consequently, magnetic flux from the opening end surface of one of the cores 29 and 30 enters the end surface of one of the large-diameter parts 22 and 23 and exiting from the other end surface after passing through the magnetic anisotropic parts 24 and 25 to enter the opening end surface of the other core 29 or 30. Consequently, the magnetic flux is prevented from being dispersed to the part of the transmission shaft 21 where magnetic anisotropy is not provided.

Description

[Detailed description of the invention] Industrial applications TECHNICAL FIELD The present invention relates to a torque measuring device, particularly for engines.

The present invention relates to a torque measuring device that can non-contactly measure the torque of motors, industrial machine drive shafts, etc.

Prior Art A conventional torque measuring device of this type is disclosed in Japanese Patent No. 1893.
There is one disclosed in the specification of No. 26. As shown in FIG. 3, this is a groove 2° 3 formed on the outer periphery of a ferromagnetic shaft 1, which forms an angle of approximately 45 degrees with the direction of the axis of rotation of this shaft 1 and is inclined in opposite directions. , and each groove portion 2.
An excitation coil 4.5 and a detection coil 6.7, which are wound around a bobbin (not shown), are arranged around the outer periphery of the coil 3, respectively.

According to such a configuration, magnetic anisotropy is imparted by the groove portion 2.3, and changes in magnetic permeability in each groove portion 2, 3 based on the transmitted torque are detected by the detection coil 6.7. At this time, since the grooves 2 and 3 are inclined in opposite directions, when a compressive force is applied to one of them, a tensile force is applied to the other. As shown in FIG. 4, the detection coil 6
．． The detection voltage 8 of one of the coils 7 increases as the torque increases, and the detection voltage 9 of the other coil decreases. Here, when the difference between the detection voltage 8 of one coil and the detection voltage 9 of the other coil is taken and combined, as shown by the solid line in FIG. A torque detection voltage 10 that shows only changes in torque is obtained by removing the effects of aging and the like.

Problem to be Solved by the Invention However, in this way, the coils 4, 3 are simply placed around the grooves 2, 3.
6..., the magnetic flux 11 is also dispersed to a portion of the shaft 1 other than the groove portion 2.3, that is, a portion to which magnetic anisotropy is not provided, and the torque measurement sensitivity becomes small. There is a problem that it cannot be done.

For this reason, as shown in FIG. 6, the coils 4, 6, etc. are housed inside a ferromagnetic core 12, and this core 12 forms a path for the magnetic flux 11, thereby distributing the magnetic flux as described above. It is conceivable to reduce the variance.

However, even in such a device, a certain degree of magnetic flux dispersion is still unavoidable, and there is a problem that it is not sufficient to improve torque measurement sensitivity.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to solve these problems and to significantly improve torque measurement sensitivity by preventing dispersion of magnetic flux as much as possible.

Means for Solving the Problems In order to solve the above problems, the present invention forms a large diameter portion with a constant width in a portion of the torque transmission shaft in the axial direction, and the torque transmission portion is formed on the outer circumferential surface of the large diameter portion. A magnetically anisotropic part is formed at an angle with the axial direction of the shaft, and a coil that can detect changes in magnetic permeability in this magnetically anisotropic part is arranged around this magnetically anisotropic part, and this coil is housed inside a core made of a ferromagnetic material and constituted by an annular body having a C-shaped cross section with an open inner circumferential side, and the open end surface of the core is connected to the large part forming the magnetic anisotropic part. They are placed facing the end face of the diameter portion.

With this type of operation, the magnetic flux emitted from one open end face of the core enters one end face of the large diameter portion opposite to this open end face, and after passing through the magnetic anisotropic portion in the axial direction, The magnetic flux exits from the other end surface of the large diameter portion and enters the other open end surface of the core. Therefore, the magnetic flux is prevented from dispersing to the portion of the torque transmission shaft where magnetic anisotropy is not provided, and the magnetic flux is It will be concentrated in the anisotropic part. As a result, the sensitivity of torque detection based on the detection of magnetic permeability changes in the magnetic anisotropic portion is greatly improved.

Embodiment In FIG. 1, 21 is a shaft for transmitting torque, and is used, for example, to transmit the output of an engine to a working device. A pair of large diameter portions 22 and 23, each having the same dimensions and a constant width, are formed at a distance from each other in a portion of the shaft 21 in the axial direction. A pair of magnetic anisotropic portions 24.25 are formed on the outer peripheral surface of the large diameter portion 22.23, forming an angle of approximately 45 degrees with the axial direction of the shaft 21 and tilting in opposite directions. . This magnetic anisotropic part 24
．． 25 can be formed, for example, by grooving the outer peripheral surface of the large diameter portion 22.23 as described above, or by gluing or plating an amorphous ferromagnetic layer on the surface of the large diameter portion 22.23. can.

A cylindrical casing 26 is supported around the shaft 21 by bearings 27,28.
Inside, annular cores 29 and 30 made of ferromagnetic material are housed at positions corresponding to the respective magnetic anisotropic portions 24 and 25. 31 is a spacer for adjusting the distance between the cores 29 and 30, and 32 is a lid of the casing.

The cores 29 and 30 are formed in a C-shaped cross section with an open inner peripheral side, and coil bobbins 33 and 34 made of a non-magnetic material such as glass epoxy are housed inside the cores. An excitation coil 35.36 and a detection coil 37.38 are wound around each coil bobbin 33.34, respectively.

The open end surface 39.40 of each core 29.30 is connected to the large diameter portion 22.
The end faces 41 and 42 of .degree.23 are arranged to face each other.

Also, each core 29.30 has a coil 35.36.37.3
These cores 29.3 are wound with bobbins 33.34
For convenience when incorporating into 0, these cores 29
30 is divided into circumferential and axial directions for convenience when arranging it around the large diameter portion 22.23.

When assembling such a device, first prepare the bobbin 3 with the coil 35, 37 wound around the large diameter portion 22 of the shaft 21.
Place 3! Then, after inserting a space 31 into the core 29 that has been split in half, a bobbin 34 with a coil 36 and 38 wound around the large diameter portion 23 of the shaft 21 is placed, and the core 29 is split in half. It is housed inside the core 30. Thereafter, these shafts 21 and cores 29.30 are integrally inserted into the casing 26, and the bearings 27.2 are attached to the gauging 26.
It is supported around the shaft 21 at 8.

At the time of torque detection, a current is applied to the excitation coils 35, 36, and a detection voltage is generated in the detection coils 37, 38. When a torque load is applied to the shaft 21, the magnetic anisotropic parts 24, 25
A magnetic permeability change occurs, and as a result, the detected voltages of the coils 37 and 38 change in the same way as in the case of FIG. As a result,
The torque value can be determined as shown in FIG.

At this time, since the open end faces 39.40 of each core 29.30 face the end faces of the large diameter portion 22.23, as shown in FIG. The magnetic flux 43 coming out from one side is
From one of the end faces 41.42 of 3 to the magnetic anisotropic portion 24.25
and the magnetic anisotropic part 24.25 to the axis 21
The end surface 41.4 of the large diameter portion 22.23
2 and the open end surface 39.4 of the core 29.30.
Enter the other side of 0.

Therefore, the magnetic flux 43 is concentrated in the magnetic anisotropy portion 24.25, and is prevented from dispersing to a portion of the shaft 21 that is not provided with magnetic anisotropy.
7.38 The gradient of the detection voltage (see Figure 4) increases, and the gradient of the torque detection voltage also increases as shown by the dashed line in Figure 5, which greatly improves the torque detection sensitivity. .

In the above, both magnetic anisotropic parts 24°25
is inclined with respect to the axial direction of the shaft 21, but either one of the magnetic anisotropic portions may be formed parallel to the axial direction.
In this case, it becomes possible to detect torque while performing sensitivity correction.

Effects of the Invention As described above, according to the present invention, magnetic flux can be concentrated on the magnetically anisotropic portion of the torque transmission shaft, and magnetic flux can be prevented from dispersing to the portion where magnetic anisotropy is not provided. Therefore, changes in magnetic permeability during torque load can be detected efficiently by the coil, and the sensitivity of torque detection can be greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the torque measuring device of the present invention;
Fig. 2 is a diagram showing the state of magnetic flux in the device shown in Fig. 1, Fig. 3 is a schematic diagram of a conventional torque measuring device, Fig. 4 is a graph showing the detected voltage in the device shown in Fig. 3, and Fig. 5 is a diagram showing the state of magnetic flux in the device shown in Fig. 1. FIG. 4 is a graph showing the torque signal based on FIG. 4, and FIG. 6 is a schematic diagram of another conventional torque measuring device. 21...Shaft, 22.23...Large diameter part, 24.25.
・・Magnetic anisotropy part, 29.30・17.37.38・・
・Detection coil, 39.40... Opening end surface, 41.42
...End face, 43...Magnetic flux. Agent Yoshihiro Morimoto

Claims (1)

[Claims] 1. A large diameter portion with a constant width is formed in a portion of the torque transmission shaft in the axial direction, and a magnetic field forming an angle with the axial direction of the torque transmission shaft is formed on the outer peripheral surface of the large diameter portion. An anisotropic part is formed, and a coil capable of detecting changes in magnetic permeability in the magnetic anisotropic part is arranged around this magnetic anisotropic part, and this coil is shaped like a C-shaped cross section with an open inner circumferential side. The core is housed in a core made of an annular body and made of a ferromagnetic material, and the open end face of the core is arranged to face the end face of the large diameter part forming the magnetically anisotropic part. A torque measuring device characterized by the following.