JPS63274810A - Position detector for rotary body - Google Patents

Abstract

PURPOSE:To cancel a temperature drift and to increase the natural oscillation frequency of a rotary body by providing one couple of position sensors each which face a surface to be detected on the surface to be detected at one radially symmetrical position and a radially symmetrical position crossing it at right angles. CONSTITUTION:A couple of position sensors X1a and X1b which face a 1st surface 17 to be detected at X-axially symmetrical positions and a couple of position sensors X1a and X1b which face the surface 17 to be detected at Y- axially symmetrical positions are provided for the surface 17 to be detected. Further, a couple of position sensors X2a and X2b which face a 2nd surface 18 to be detected at X-axially symmetrical positions and a couple of position sensors Y2a and Y2b which face the surface 18 to be detected at Y-axially symmetrical positions are provided for the surface 18 to be detected. Consequently, the temperature drift is canceled, and the rotary body is shortened to increase the natural oscillation frequency. Each sensor outputs variation in inductance at the time of variation in the distance to the surface to be detected as the quantity of electricity.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a position detection device for a rotating body, more specifically,
For example, a device for detecting the positions in two mutually orthogonal radial directions (X-axis and Y-axis directions) and the axial direction (Z-axis direction) of a rotating body such as a rotor shaft or a cylindrical rotor of a magnetic bearing device. Regarding.

Conventional technology and its problems Magnetic bearing devices generally use a total of four sets of radial bearings that control the positions in the X-axis and Y-axis directions at two locations separated in the axial direction of the rotor shaft, and in the axial direction of the rotor shaft. A five-axis control type equipped with a set of axial bearings that controls the position of the motor is known.

In such a conventional five-axis controlled magnetic bearing device, two radial position sensors are disposed facing each other for each axis for the X-axis and the pY-axis to cancel out temperature drift. Therefore, eight radial position sensors are required to detect the positions in the X-axis and Y-axis directions at two locations on the rotor axis, respectively. Regarding the Z-axis, only one axial position sensor is often used due to space constraints, but this tends to cause temperature drift. If you want to cancel temperature drift, you can place two axial position sensors facing each other on the Z-axis as well, but if you do this, the rotor axis will be lengthened by that much, and the bending natural vibration of the rotor axis will be reduced. There is a problem that the number decreases. Normally, the maximum rotational speed of the rotor shaft is 70 to 80% of the natural frequency, but as the natural frequency decreases, the maximum rotational speed is kept low, making high-speed rotation impossible. Further, in the conventional five-axis controlled magnetic bearing device, as is clear from the above explanation, at least nine position sensors are required, and ten position sensors are required if temperature drift is to be canceled for the Z-axis as well.

An object of the present invention is to provide a position detection device for a rotating body that can solve the above problems, cancel temperature drift, shorten the rotating body to increase the natural frequency, and require fewer position sensors. There is a particular thing.

Means for Solving the Problems A position detecting device for a rotating body according to the present invention is a position detecting device for detecting two mutually orthogonal radial positions and an axial position of a rotating body. Tapered detection surfaces facing opposite sides in the axial direction are formed at two locations separated in the axial direction, and for each detection surface, a pair of detection surfaces facing the detection surface at one radially symmetrical position are formed. A position sensor and a pair of position sensors facing the detection surface at radially symmetrical positions orthogonal thereto are respectively provided.

Function By processing the outputs of the four pairs of position sensors in the same way as the conventional four pairs of radial position sensors, displacements in two mutually orthogonal radial directions at two locations separated in the axial direction of the rotating body, that is, Displacement in 4 axes is required. Also,
By taking the difference between the sum of the outputs of the four position sensors corresponding to one detected surface and the sum of the outputs of the four position sensors corresponding to the other detected surface, the The axial displacement is required.

Embodiment FIG. 1 shows a longitudinal section of a five-axis controlled magnetic bearing device in which a rotor shaft (11) rotates inside a cylindrical fixed case (10). Figures 2 and 3 show two axially separated cross sections of the rotor shaft (11) of this device. In the following description, of the two mutually orthogonal radial directions of the rotor shaft (11), the horizontal direction in FIGS. 2 and 3 is referred to as the X-axis direction, and the vertical direction in the same figures is referred to as the Y-axis direction, and The axial direction of the shaft (11), that is, the left and right direction in Fig. 1 is
In the axial direction. Further, regarding the X-axis direction, the left and right in FIG. 1 are referred to as left and right.

The fixed case (lO) of the magnetic bearing device has the following:
A total of five sets of magnetic bearings are provided.

That is, one set of radial magnetic bearings (not shown) that controls the position of the rotor shaft (11) in the X-axis direction and one set of radial magnetic bearings (not shown) that control the position of the rotor shaft (11) in the Y-axis direction are located at one location near the left end of the rotor shaft (11).
A set of radial magnetic bearings (12a) and (12b) are provided, and a set of radial magnetic bearings that control the position of the rotor shaft (11) in the X-axis direction is also provided at a location to the right of the X-axis direction. 1 that controls the magnetic bearing (not shown) and the position in the Y-axis direction
A set of radial magnetic bearings (13a) (13b) is provided. A disk (14) is integrally provided at a portion near the right end of the rotor shaft (11), and this disk (
A pair of axial magnetic bearings (15a) (L
5b) is provided. Further, a high frequency motor (1B) is provided between the left and right radial magnetic bearings (12a), (12b), (13a), and (13b). The rotor shaft (11) has magnetic bearings (12a) (12b).
) (13a) (13b) (15a> (15b)
It is supported in a non-contact manner and rotates at high speed.

The position detection device for the rotor shaft (1) of the magnetic bearing device described above is configured as follows.

A tapered first detection surface (17) facing left is formed on the outer periphery of the rotor shaft (11) immediately to the left of the left radial magnetic bearing (12a) (12b), and the right radial magnetic bearing (13a) ) (13b) immediately to the right of the rotor shaft (11
) on the outer periphery of the tapered second detection surface (1
8) is formed. In addition, these detection surfaces (17
)(18) is, for example, 45 degrees.

As shown in FIG. 2 for the first detection surface (17).

A pair of position sensors (X la) (X 1 b) facing the detection surface (17) at symmetrical positions in the X-axis direction
) (hereinafter referred to as the first X-axis sensor) and a pair of position sensors (Yla) (Ylb) (hereinafter referred to as the first Y-axis) facing the detection surface (17) at symmetrical positions in the Y-axis direction are provided. . Note that the location where the first detection surface (17) of the rotor shaft (ll) is provided is referred to as the first location. With respect to the second detection surface (18), as shown in FIG. 3, a pair of position sensors (X 2a
) (X 2b) (hereinafter referred to as the second X-axis sensor) and a pair of position sensors (Y 2a) (Y 2b) facing the detection surface (18) at symmetrical positions in the Y-axis direction.
(hereinafter referred to as the second Y-axis) is provided. In addition,
The location of the rotor shaft (11) where the second detected surface (18) is provided will be referred to as a second location. Note that each position sensor is an inductance detection type non-contact position sensor, and when the distance to the detection surface changes, the change in inductance is extracted as an amount of electricity, and the same distance is thereby detected.

FIG. 4 shows part of the electrical configuration of the above-mentioned position detection device.

A pair of first X-axis sensors (X la) (X lb)
The output signal of the pair of first Y-axis sensors (Yla) (Ylb) is sent to the differential amplifier (20), and the output signal of the pair of first Y-axis sensors (Yla) (Ylb) is sent to the differential amplifier (20).
) (X 2b) is sent to the differential amplifier (21).
The output signals of the pair of second Y-axis sensors (Y 2a) (Y 2b) are respectively input to differential amplifiers (22), and each differential amplifier <19) (20) (21) (22) is 2
Outputs the difference between two input signals. Then, a differential amplifier (1
9) output signal (S xi) is the first output signal (S xi) of the rotor shaft (11).
The output signal (S yl) of the differential amplifier (20) corresponds to the displacement of the first point in the Y-axis direction, and the output signal (S x2) of the differential amplifier (21) corresponds to the displacement of the first point in the X-axis direction. The output signal (S y
2) are each proportional to the displacement in the Y-axis direction of the second location, and due to these, the X
Displacements in the axial and Y-axis directions (total of 4 axial directions), that is, in the radial direction, are determined. Note that these signals (S xi)
The circuit for determining (S yl) (S *2) (S y2) is similar to the circuit for determining the displacement in the four-axis directions from the output signals of the four pairs of radial position sensors in the conventional position detection device. be. Furthermore, since a pair of position sensors are arranged facing each other for each axis, temperature drift can be canceled out. On the other hand, the first X-axis sensor (X la) (X lb) and the first Y-axis sensor (Y
la) (Y lb) output signal is passed through the current amplifier (2B
)(27) (2g) After passing through (29), it is input to the first adder (23), and the second X-axis sensor (X2a)
(X 2b) and the second Y-axis sensor (Y 2a) (Y
The output signal of 2b) is passed through current amplifiers (30) (31) (
32) After passing through (33), it is input to the second adder (24). Then, the output signal of the first adder (23) (
S zl) and the output signal (S z
2) is input to the differential amplifier (25).

The output signal (S zl) of the first adder (23) is transmitted to the four sensors (X la) (X lb) at the first location.
It is the sum of the output signals of (Yla) (Ylb) and is proportional to their average value. Second adder (2
The output signal (S z2) of 4) is output from the four sensors (X 2a) (X 2b) (Y 2a) at the second location.
(Y 2b) and is proportional to their average value. Therefore, the differential amplifier (2) which is the difference between these output signals (Szl) (Sz2)
The output signal (S z ) of 5) is proportional to the displacement of the rotor shaft (11) in two axial directions, that is, in the radial direction, and this displacement can be determined thereby. Since the displacement in the Y-axis direction is determined from the output signals of two sets of sensors arranged opposite to each other in the Y-axis direction, it is possible to cancel the temperature drift.

In this way, in the above position detection device, the rotor shaft (11
) can detect displacement in a total of five axes, including displacement in the X- and Y-axis directions and displacement in two-axis directions, using eight sensors, and is also able to cancel temperature drift in all five axes. I'll come. In addition, the eight sensors are arranged in almost the same way as conventional radial position sensors, and there is no need for a device equivalent to a conventional axial position sensor, so the rotor axis (11) can be shortened accordingly. , the natural frequency of the rotor shaft ([1) increases. Therefore, the maximum rotational speed of the rotor shaft (11) can be increased, and high-speed rotation becomes possible.

The present invention can also be applied to a magnetic bearing device in which a cylindrical rotor rotates around a fixed shaft.

In this case, the detection surface may be formed on the inner circumferential surface of the rotor, or may be formed on the outer circumferential surface of the rotor. Moreover, this invention
It can also be applied to rotating bodies other than magnetic bearing devices.

Effects of the Invention According to the position detection device of the present invention, the displacement of the rotating body in the five-axis directions can be detected by eight position sensors, and the number of position sensors can be smaller than that of the conventional device. In addition, it is possible to cancel temperature drift not only in the radial direction of the rotating body but also in the axial direction, and since it eliminates the need for a device equivalent to a conventional axial position sensor, the rotating body can be shortened and its bending natural frequency can be reduced. can be increased.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a magnetic bearing device showing an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line ■-■ in FIG. 1, and FIG. FIG. 4 is a block diagram showing the electrical configuration of the position detection device. (11)...Rotor axis, (17)(18)...Detected surface, (Xla) (Xlb) (Yla) (
Ylb) (X2a) (X2b) (Y2a)
(Y2b) ...Position sensor. that's all

Claims (1)

[Claims] A position detection device for detecting two mutually orthogonal radial positions and an axial position of a rotating body, the device comprising: Tapered detection surfaces facing opposite sides are formed, and for each detection surface, a pair of position sensors facing the detection surface at one radially symmetrical position and a radially symmetrical position orthogonal thereto. A position detection device for a rotating body, in which a pair of position sensors facing a detection surface are respectively provided.