JPS6219923Y2 - - Google Patents

Description

[Detailed explanation of the idea] This invention relates to a rotation angle detector.

Conventional rotation angle detectors partially detect using contacts or continuously detect using potentiometers, etc., but since there are sliding parts such as contacts, poor contact may occur, resulting in poor durability and reliability. There was a problem.

This invention was made in view of the problems of conventional rotation angle detectors, and aims to provide a non-contact type rotation angle detector that can detect continuous quantities.

These can be detected without contact by using a pulse generator such as a rotary encoder, and although they are not continuous quantities, they can be detected by mechanical magnifying means.
Detection is also possible by dividing the pulses. However, this detector is extremely expensive as a whole.

This idea consists of fixing a magnetically sensitive element in such a way that it faces a permanent magnet that is given motion by a cam that rotates at the same constant rotation ratio as the rotating body that is the object to be measured, and allows the magnetic flux of the permanent magnet to pass through. The magnetic flux density passing through the magnetically sensitive elements is changed by changing the air gap between the magnetically sensitive elements, and the rotation angle of the rotating body is detected based on the electrical output.

Embodiments of this invention will be described below with reference to the drawings.

FIG. 1 is a front view, and FIG. 2 is a side view of FIG. 1. A cam 3 is fixed to a shaft 2 connected to a rotating body 1, which is an object to be measured whose rotation angle is detected, so as to rotate together with the rotating body 1. In this embodiment, the rotating body 1 and the cam 3 are rigidly connected via the shaft 2, but they are precisely connected with almost no slippage, such as by winding transmission using a rigid band as a belt. They may be connected to rotate at a constant rotation ratio. As shown in Figure 1, the contour of the cam 3 has a radius that gradually increases from point 3a to point 3b over a period of 90 degrees in the direction of the arrow in the figure, and from point 3b to point 3c clockwise in Figure 1, the radius remains constant. , that is, a circle, and a straight line between points 3c and 3a.

A permanent magnet 4 is fixed to a non-magnetic holder 5 that serves as a cam follower, one end of a spring 6 is rigidly fixed to the holder 5, and the other end of the spring 6 is rigidly fixed to a support 8. Holder 5
is pressed and supported by a spring 6 toward the cam 3.

In this configuration, the holder 5 is omitted and the permanent magnet 4 is brought into direct contact with the non-magnetic cam 3.
One end of the spring 6 may be rigidly fixed to the support body 8, and the other end of the spring 6 may be rigidly fixed to the support body 8. A magnetically sensitive element 7 is fixed to a support 8 facing either pole of the permanent magnet 4, and in the state shown in the figure, the gap between the permanent magnet 4 and the magnetically sensitive element 7 is close to zero. .

Magnetic flux is distributed in the space near the permanent magnet 4, which is the source of the magnetic field, and the density of this magnetic flux changes with the distance from the permanent magnet 4. Therefore, by arranging the magnetically sensitive element 7 at a position facing the permanent magnet 4, the change in distance from the permanent magnet 4, that is, the change in magnetic flux density, can be extracted by the magnetically sensitive element 7 as an electrical output.

Assuming that the cam 3 is in contact with the holder 5 at point 3a in FIG. The output voltage of element 7 is also small. When the rotating body 1 rotates, the cam 3 rotates via the shaft 2. Now cam 3 is point 3
If it contacts the holder 5 at point a and rotates counterclockwise, the holder 5 will move between points 3a and 3b.
is gradually pushed up by the cam 3 against the spring 6, the permanent magnet 4 rises, and the gap between it and the magnetically sensitive element 7 decreases, so that the magnetic flux density increases and passes through the magnetically sensitive element 7. The output voltage of the magnetically sensitive element 7 gradually increases. Therefore, there is a correspondence between the rotation angle of the rotating body 1 and the output voltage of the magnetically sensitive element 7.
The rotation angle of the rotating body 1 can be detected.

Figure 3 shows one of the characteristics of the rotation angle detector of this invention.
In this example, the horizontal axis shows the rotation angle of the cam 3, and hence the rotation angle θ of the rotating body 1, and the joint axis shows the output voltage V _H of the magnetically sensitive element 7, and the relationship between the two is shown. A characteristic curve 9 shown in FIG. In this embodiment, as shown in this figure, the rotation angle θ of the rotating body 1 and the output voltage V _H of the magnetically sensitive element 7 are in a linear proportional relationship. The slope of this characteristic curve 9 can be varied by changing the contour of the cam 3.
Further, depending on the purpose, the contour of the cam 3 may be changed so that the characteristic curve 9 becomes a desired curve. Magnetically sensitive element 7
The output voltage V _H is amplified and displayed on a display, or the rotation angle θ of the rotating body 1 is directly displayed. It can also be used as an input to a subsequent control circuit.

In this embodiment, the spring 6 is a leaf spring, but a coil spring may also be used. In addition, the magnetically sensitive element 7
It is more effective to add a yoke to the magnetically sensitive element 7 to focus the magnetic force.

As described above, according to the rotation angle detector of this invention, a permanent magnet is reciprocated using a cam that rotates at a constant rotation ratio with the rotating body that is the object to be measured, and the air gap between the permanent magnet and the fixed magnetically sensitive element is closed. By changing the structure, there is no contact, so there is no electrical contact failure due to wear, and the structure is simple and has excellent durability and reliability. By using the cam, it is possible to obtain a desired change in the characteristic curve that relates the rotation angle of the rotating body to the electrical output. The rotation angle range can be arbitrarily selected from 0 to 360 degrees regardless of the embodiment.

[Brief explanation of the drawing]

FIG. 1 is a front view of an embodiment of this invention, FIG. 2 is a side view of FIG. 1, and FIG. 3 is a drawing showing the characteristic curve of the embodiment. 1...Rotating body, 2...Shaft, 3...Cam,
4...Permanent magnet, 5...Holder, 6...Spring,
7...Magnetic sensitive element, 8...Support, 9...Characteristic curve.

Claims (1)

[Scope of utility model registration request] It consists of a cam that rotates at a constant rotation ratio with respect to the rotating body that is the object to be measured, a permanent magnet that is pressed and supported by a spring against the cam, and a magnetically sensitive element that is fixedly installed opposite to the permanent magnet. Rotation angle detector.