JPS61290229A - Magnetic bearing controller - Google Patents

Abstract

PURPOSE:To absorb thermal deformation within the range of bearing gap by varying the magnitude of position setting signal with correspondence to the temperature at random portion of rotary unit measured through a temperature meter then comparing with a position signal produced from a position detector. CONSTITUTION:The temperature at heated section is measured through a temperature meter 11 to vary the magnitude of position setting signal to be fed from position setting circuit 7 thus to move the rotor 3 of magnetic bearing up and down within the range of gap against the stator and to minimize the variation of gap between the dynamic vane and the static vane due to thermal deformation. Upon measurement of temperature (t) through said meter 11, position setting circuit 7 will produce a position setting signal (e) to comparing circuit 6 in accordance to an incorporating function F (t).

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a magnetic bearing control device, and in particular to magnetic bearing control of a controlled magnetic bearing suitable for supporting a rotating shaft of a high-speed rotating machine exposed to high or low temperatures. It is related to the device.

[Background of the invention]

Conventional controlled magnetic bearings are used to support rotating shafts in high-speed rotating machinery. Japanese Patent Application Publication No. 52-89088,
It is described in Japanese Patent Application Laid-Open No. 59-93992.

The former is an example of application to a rotating anode type X-ray tube, and the latter is an example of application to an axial flow molecular pump. All of these may operate under temperature conditions different from normal temperature. However, no consideration was given to setting the position of the rotating shaft when the temperature changes.

When a rotating device is exposed to high or low temperatures, thermal expansion or contraction occurs in the rotating shaft and fixed portion. In conventional controlled magnetic bearings, even if thermal deformation occurs, the gap between the stator and rotor of the magnetic bearing, where the position detector is installed, is controlled to be kept constant, so the bearing of the rotating shaft Other parts are greatly affected by thermal deformation. For example, in a rotating anode X-ray tube, the position of the rotating anode shifts due to thermal deformation, so the optical axis of the emitted X-rays changes from its initial adjusted state, and readjustment is required. Furthermore, in the case of an axial flow molecular pump or a helium expansion turbine, the efficiency changes because the gap between the moving blade and the stator blade changes. In many cases, the change in efficiency results in a decrease in efficiency.

As mentioned above, when a temperature change is applied to a rotating device that uses controlled magnetic bearings, thermal deformation occurs.
There were problems such as decreased efficiency. This phenomenon is a problem that also exists when bearings such as sliding bearings and rolling bearings, which have been commonly used in the past, are used.

[Purpose of the invention]

The present invention was made in order to solve the problems of the prior art as described above, and even if a temperature change is applied to a high-speed rotating machine or a temperature change occurs, the present invention can be applied to any position within the bearing gap. Taking advantage of the feature of controlled magnetic bearings that the rotation axis can be set to

The object is to provide a magnetic bearing control device capable of absorbing thermal deformation within the bearing gap.

[Summary of the invention]

The configuration of the magnetic bearing control device according to the present invention includes a position detector that detects the set position of the rotating shaft to which the rotor of the magnetic bearing is fixed, and a device signal constituted by this position detector and a position setting signal that are compared. , a magnetic bearing control device comprising a control circuit that inputs and processes the deviation signal, and a power amplification circuit that controls the power applied to the stator excitation coil of the magnetic bearing according to the output of the control circuit. A temperature measuring device that measures the temperature of a given part of a rotating device in which a magnetic bearing is used; and a temperature measuring device that changes the magnitude of the position setting signal according to the temperature measured by the temperature measuring device, and transmits the position setting signal from the position sensor. It is designed to be compared with the configured device signal.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 is a block diagram of a control device for a controlled magnetic bearing according to an embodiment of the present invention, and FIG. 2 shows the magnitude of the position setting signal when a temperature change is applied to the device of FIG. FIG. 6 is an explanatory diagram of another example of changing the height.

In FIG. 1, reference numeral 1 denotes a rotating shaft of a high-speed rotating machine to which a rotor 3 of a magnetic bearing is fixed. 2 is a magnetic bearing, which consists of a stator and a rotor. Reference numeral 4 denotes a detection section of a position detector that detects the set position of the one-rotation shaft 1, and outputs a predetermined position signal from the position detector 5. Reference numeral 6 denotes a comparison circuit that compares the device signal constituted by the position detector 5 and the output signal of the position setting circuit 7 to obtain a deviation signal, and 8 a control circuit that inputs the deviation signal from the comparison circuit 6 and processes it. , 9 is a power amplification circuit that controls the power applied to the stator excitation coil 10 of the magnetic bearing according to the output of the control circuit 8.

Reference numeral 11 denotes a temperature measuring device that measures the temperature of any part of a rotating device in which a controlled magnetic bearing is used, and according to its temperature output signal, the position setting circuit 7 sets the position [M The magnitude of the constant signal is changed and outputted to the comparator circuit 6. These position detectors5. Control circuit 8. A control device for the magnetic bearing 2 is configured by the power amplification circuit 9 and the like.

This embodiment shows an example in which the thrust control type magnetic bearing control device is applied to an axial flow molecular pump.

The operation will be explained.

The position detector detection unit 4 detects the gap between the rotating shaft 1 and the rotating shaft 1 facing each other, and the control device controls the detected gap to be equal to the set position. In a trickle-flow molecular pump, a heating operation called baking is performed on the suction side of the pump to obtain a high vacuum.

Therefore, thermal deformation inevitably occurs between the fixed part of the pump and the rotating shaft. In the conventional case, the gap between the stator vane and rotor blade also varied, resulting in a decrease in efficiency. Therefore, in the present invention, the temperature of the heated part is measured by the temperature measuring device 11, and as shown in FIGS. 2 and 3, the magnitude of the position setting signal of the position setting circuit 7 is changed, and the rotation of the magnetic bearing is controlled. The position of the child 3 is moved up and down within the gap between the stators to minimize changes in the gap between the moving blade and the stationary blade due to thermal deformation.

This will be explained with reference to FIG. Initially, the magnitude of the position setting signal is set to eo at the temperature t0. A magnetically bearing rotor 3 fixed to a rotating shaft l is mounted e within a gag between the stators. is set to the position corresponding to. When the temperature measuring device 11 measures the temperature 11+- of the heated portion due to heating, the position setting circuit 7 outputs a position setting signal e to the comparison circuit 6 in accordance with the internally incorporated function F(t). This causes the magnetic bearing rotor 3 to e.g. within the gap between the stators. This minimizes changes in the gap between the rotor blade and the stator blade due to thermal deformation. F(t) is a function selected to minimize the influence of thermal deformation, and may be obtained by actual measurement or calculation. Also, the function F(
t), the output signal is limited as shown in FIG. 2(b) so that the magnetic bearing rotor 3 moves only within the gap between the stators. The function F(t) may be incorporated into the position setting circuit 7 using hardware or software.

In FIG. 2, the case where the temperature measuring device 11 measures the temperature at any one point of the heating part is shown, but in FIG. 3, when the temperature measuring device 11 measures the temperature at any plural points, especially when @
1 and the case where the temperature on the fixed side is measured is shown. The gap between the rotor blades and stationary blades of an axial flow molecular pump is defined by the rotation axis 1. Since the temperature depends on the temperature difference between The position W setting circuit 7 includes 1. -1. A function F(t, -t,) is incorporated which outputs a position setting signal depending on the value of . The operation is similar to that described in FIG.

To maintain a constant gap between the moving and stationary blades.

It is also possible to measure this gap with the position detector detection section 4 and thereby control the thrust control layer magnetic bearing, but generally the position detector detection section 4 has temperature characteristics and is installed in the heating section. It is desirable that the six-position detector detecting section 4 is installed in a place where the temperature changes little. In the embodiment of FIG. 1, this location is the illustrated location at the bottom of the pump body.

Although this embodiment has been described as a thrust control type magnetic bearing control device, it is of course applicable to a radial control type magnetic bearing control device.

Further, although the description has been given as an example of application to an axial flow molecular pump, it goes without saying that the invention can be applied to other rotating mechanical devices.

Further, the temperature measuring device 11 may be a contact type thermometer such as a heat@thermometer or a sursistor thermometer, or a non-molten layer thermometer such as an infrared radiation thermometer.

〔Effect of the invention〕

As described above, according to the present invention, even if a temperature change is applied to a high-speed rotating machine or a temperature change occurs,
A magnetic bearing control device capable of absorbing thermal deformation within the bearing gap can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a control device for a controlled magnetic bearing according to an embodiment of the present invention, and FIG. 2 shows the magnitude of the position setting signal when a temperature change is applied to the device in FIG. FIG. 3 is an explanatory diagram of another example of changing the magnitude of the position setting signal. 1...Rotating shaft, 2...Magnetic bearing, 3...Rotor,
4...Position detector detection section, 5...Position detector, 6.
. . Comparison circuit, 7. Position setting circuit, 8. Control circuit, 9. Power amplifier circuit, 10. Stator excitation coil, 11. Temperature measuring device. Agent Patent Attorney No J Clause 11 Katsuo) (, Pa, -1

Claims (1)

[Claims] 1. A position detector detects the set position of the rotating shaft to which the rotor of the magnetic bearing is fixed, and the position signal output from this position detector is compared with the position setting signal, and the deviation signal is input and calculated. A magnetic bearing control device comprising a control circuit for processing and a power amplification circuit for controlling power applied to a stator excitation coil of the magnetic bearing according to the output of the control circuit,
A temperature measuring device that measures the temperature of any part of the equipment in which the magnetic bearing is used; and a temperature measuring device that changes the magnitude of the position setting signal according to the temperature measured by the temperature measuring device and outputs it from the position detector. What is claimed is: 1. A magnetic bearing control device characterized in that the device is configured to compare the position signal with the position signal received by the user.