JPH01169308A - Non-contact displacement detection device - Google Patents

Abstract

PURPOSE:To detect the displacement in a radial direction and the displacement in the thrust direction independently with a structure of a low cost, by providing a tapered part at the displacement detecting part of a rotary shaft, and obtaining the sum and the difference between the outputs of the displacement detectors with a transducer. CONSTITUTION:Differential transformer type X-direction displacement detectors 3 and 4 and Y-direction displacement detectors 5 and 6 are provided so that they are not in contact with a rotary shaft 1. A tapered part 2 is formed at the displacement detecting part of the rotary shaft 1, which faces the displacement detectors 3-6. The detected outputs of the displacement detectors 3-6 are inputted into a transducer 7. The displacement in the thrust direction is detected based on the sum of the outputs. The displacement in the radial direction is detected based on the difference between them. In this way, the radial displacement and the thrust displacement can be detected without increasing the number of the displacement detectors 3-6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a displacement detection device that detects displacement of an object to be detected in a non-contact manner.

[Conventional technology]

The use of a differential transformer to detect the displacement of a rotating shaft in the radial direction is known as described in Japanese Patent Application Laid-Open No. 59-105516. Here, the principle of detecting displacement in the radial direction will be explained.

One of the radial directions is defined as the X direction.

In order to detect displacement in the X direction, differential transformers are placed on the left and right sides of the X direction around the rotation axis. Here, the differential transformer is referred to as a detector 1.2. Differential transformer type detectors utilize the fact that the inductance of the coil changes when the displacement of the object to be detected changes.If the coil is excited with a constant AC voltage, the inductance of the coil changes as the displacement changes. , it uses the fact that the output voltage of the differential transformer changes.

Here, the outputs of the detectors 1 and 2 are respectively el.

Let e2 be the output of the converter that provides the displacement of the rotation axis in the X direction. The el and ez are inversely proportional to the distance, and the ex is the difference between at and 82 inside the converter. If the respective distances between the detector 1.2 and the rotation axis are equal, aX=O.If the rotation axis moves toward the detector 1, el>e2, so ex >.

If the rotating shaft moves in the opposite direction, e-<0, and the displacement of the rotating shaft can be determined by eX.

In the prior art, as described in Japanese Unexamined Patent Publication No. 59-105516, it has been discussed how to improve the detection accuracy of the above detection method.

[Problem that the invention seeks to solve]

Conventionally, for detecting displacement in the thrust direction, a detector was provided separately from a detector in the radial direction. However, since vacuum pumps have an impeller at one end of the rotating shaft, it is difficult to install a detector. For this reason, there are eddy current type detectors that can detect only one end face of one rotation axis, which excite the coil at several megahertz and detect changes in the coil current due to eddy currents generated in the conductor target, and capacitance between two conductors. is a function of the distance, and there are capacitive detectors that detect this, but these detectors require a dedicated converter, making them extremely expensive.

SUMMARY OF THE INVENTION An object of the present invention is to provide detection of displacement in the radial direction and the thrust direction using a displacement detector provided in the radial direction using an inexpensive differential transformer.

[Means for solving problems]

The above object is achieved by tapering the displacement detector of one rotational axis and by using a converter to determine the sum and difference of differential transformer type detectors installed in a pair on the left and right sides of one rotational axis.

[Effect]

The taper provided on the displacement detector of the rotating shaft allows the distance between the rotating shaft and the detector to change even when the rotating shaft moves in the radial direction or in the thrust direction. In addition, displacement in the radial direction can be detected by taking the difference in the outputs of a pair of differential transformer type detectors installed on the left and right sides of the single rotation axis inside the converter, and the sum is taken inside the converter to determine the reference value. By comparing, displacement in the thrust direction can be detected.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, the X-axis and Y-axis are coordinates taken in the radial direction. The Z axis is a coordinate taken in the thrust direction. 1 is a rotating shaft, and 2 is a taper, which is provided in a displacement detection section of the rotating shaft so that the diameter of the rotating shaft 1 increases in the Z-axis direction. Reference numerals 3 and 4 denote X-direction detectors, which are installed on the left and right sides of the one-rotation shaft 1 in the X-axis direction. Reference numerals 5 and 6 indicate Y-direction detectors, which are installed on the left and right sides of the rotating shaft 1 in the Y-axis direction. 1
3 and 14 are X-direction displacement signals, and the X-direction detector 3°4
This is the output of 15 and 16 are Y direction displacement signals, Y
These are the outputs of the direction detectors 5 and 6. 7 is a converter to which an X-direction displacement signal 13.14 and a Y-direction displacement signal 15.16 are input. 8 is an X-direction radial displacement signal, and converter 7
This is the difference between the X direction displacement signals 13 and 14 within the . 9 is a Y-direction radial displacement signal, which is obtained by taking the difference between the Y-direction displacement signals 15 and 16 inside the converter 7.

12 is a thrust displacement reference value. 10 is an X-direction thrust displacement signal, and inside the converter 7, an X-direction displacement signal 13.
14 and compared with the thrust displacement command 12. 11 is a Y-direction thrust displacement signal, and the converter 7
The sum of the Y-direction displacement signals 15 and 16 is calculated within the Y-direction displacement command 12 and compared with the thrust displacement command 12. 17 is a subtracter that takes the difference between two inputs, and 18 is an adder that takes the difference between two inputs.
It calculates the sum of two inputs.

In FIG. 1, the operation when the rotating shaft 1 swings in the X-axis direction will be described. Here, FIG. 4 shows an example of the internal circuit of the converter 7. The X direction radial displacement signal 8 is
The difference between the X direction displacement signals 13 and 14 (by the subtractor 17)
This is what I took. The Y-direction radial displacement signal 9 is the difference between the Y-direction displacement signals 15 and 16 (by the subtracter 17).

The X-direction thrust displacement signal 10 is obtained by calculating the difference between the sum of the X-direction displacement signals 13 and 14 and the thrust displacement command 12 (using the subtracter 17). The Y-direction thrust displacement signal 11 is the sum of the Y-direction displacement signals 15 and 16 (
by the adder 18) and the thrust displacement command 1
2 (by subtractor 17), X
directional displacement signals 13 and 14 respectively. □Set as ate14. Letting the X-direction radial displacement signal 8 be ell, the internal operation of the converter 7 is expressed as es=exδ-814. Here, if the distance between the rotating shaft 1 and the X-direction detector 3.degree. 4 is equal, eg==Q, indicating that the rotating shaft 1 does not oscillate. In this case, even if the rotating shaft 1 moves in the thrust direction, the rotating shaft 1 and the X-direction displacement detectors 3 and 4
Since each distance to and changes at the same rate, e8=
o, and then when the rotating shaft 1 moves toward the X-direction detector 4, es>O or es>O, and the displacement of the rotating shaft 1 can be detected. Even when moving in the opposite direction, displacement can be detected by a similar operation. In this case, when the rotating shaft 1 moves in the thrust direction, the distances between the rotating shaft 1 and the X-direction displacement detectors 3 and 4 change at the same rate, so the displacement in the radial direction is not affected.

The operation is similar to the above operation when the rotating shaft 1 moves in the Y-axis direction.

In Figure 2, the rotating shaft 1 is in two axial directions (thrust direction).
This section explains what happens when you take a picture. Inside the converter 7, the X-direction thrust displacement signal 10 is synthesized from the X-direction displacement signal 13.degree. 14 and the thrust displacement command 12 as described above.

X-direction displacement signal 13°14 respectively e111. e
14, the thrust displacement command 12 is eix, and the X-direction thrust displacement signal 10 is 810. The above operation is performed inside the converter 7 and is expressed by the following equation.

ezo=exx CB111+814) When the rotating shaft 1 is in the position according to the thrust displacement command 12, e xx
= e s+ e a, that is, eto=0. Here, if the rotation axis moves in the positive direction of the Z-axis, ext>
ea+e4 or ext<es+e4. That is, exa<O or e<o>O, and the displacement of the rotating shaft 1 can be detected. In this case, even if the rotating shaft 1 moves in the radial direction, the value of es+e+ remains constant, so it does not affect the detection of displacement in the thrust direction.The same operation occurs even if the rotating shaft 1 moves in the opposite direction to the above direction. It can be detected by

In FIG. 2, in order to improve the detection accuracy of the X-direction detectors 3 and 4, the detection surfaces of the X-direction detectors 3 and 4 are installed parallel to the tapered surface. . That is, when the X-direction detectors 3 and 4 are installed horizontally as shown in FIG. 3, the detectors 3 and 4 cannot detect only a certain point, so if there is a taper, the This is because only the averaged distance of the slope can be detected, resulting in a decrease in detection accuracy.

The same applies to the Y-axis direction.

〔Effect of the invention〕

According to the present invention, there is no need to separate displacement detectors for the thrust direction and the radial direction, so the number of detectors can be reduced.

Furthermore, since the number of detectors is small, there is an effect that the configuration can be simplified.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a detector arranged around the rotation axis according to an embodiment of the present invention, and FIGS. 2 and 3 are 1--1 in FIG. 1.
A one-line cross-sectional view, FIG. 4, is an embodiment of the converter circuit. DESCRIPTION OF SYMBOLS 1... Rotation axis, 2... Taper, 3, 4... X direction detector, 5.6... Y direction detector, 7... Converter,
8...X-direction radial displacement signal, 10...X-direction thrust displacement signal. Dream l figure! ...Rotation axis 3...

Claims (1)

[Claims] 1. A displacement detector provided for non-contact detection of displacement in the radial direction of a rotating shaft, and a converter for converting an output signal from the detector into a displacement signal. , a taper is provided in the displacement detector insertion portion of the rotating shaft, a radial component displacement and an axial direction (thrust direction) component displacement are applied to the displacement detector, and the difference between these components is taken within the converter to determine the radial displacement. 1. A non-contact displacement detection device characterized by being able to detect thrust displacement by calculating the sum.