JPH0356710A - Spindle support of magnetic bearing device - Google Patents

Abstract

PURPOSE:To reduce the wear in a thrust receiving plate by installing an actuator which makes minute displacement of a spindle and a pressure sensor for an axial load detection on the receiving plate and controlling the axial load into a prescribed value through the signal. CONSTITUTION:A spindle 1 is supported by a radial bearing consisting of a magnetic pole 2 and a magnetic pole 3 installed externally, and a ceramic ball 4 is mounted on both end faces of the spindle 1 supported by a thrust receiving plate 5 made of a hard material through an actuator 7 fixed on a housing 8 and a pressure sensor 6. The actuator 7 is constructed of a piezoelectric element and the like, and the spindle 1 is displaced minutely to input on axial load signal of the pressure sensor 6 into a control part 9 where the load is compared with the prescribed value. When a larger load than a fixed valve is applied the actuator 7 is driven. It is thus possible to minimize the wear in the thrust receiving plate 5 to be used in a vacuum equipment of high purity.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a spindle support device for a magnetic bearing device.

(Prior art) When a radial load is received by a magnetic bearing using a permanent magnet in a spindle of a motor, etc., radial load is If you try to stably receive the axial load in the axial direction, it can only be received in an unstable state.

In order to stabilize unstable axial loads, conventionally a ceramic ball was installed protruding from the end of the spindle, and a flat plate made of hard material was installed on the receiving side. (Problems to be Solved by the Invention) In the above-mentioned prior art, wear occurred between the hard bodies of the ceramic ball at the end of the spindle and the flat plate in contact with the ball due to the generation of axial load. As this amount of wear increases, the relative axial position of the permanent magnet of the spindle and the permanent magnet of the radial bearing disposed opposite to it shifts, resulting in a decrease in radial load resistance, resulting in the rotational accuracy of the spindle. This was a factor that worsened the situation. Furthermore, since the contact area increases due to an increase in the amount of wear, the axial load gradually increases, increasing the rotational torque of the spindle, and reducing the rotational performance of the spindle.

(Means for Solving the Problems) The present invention aims to solve the above problems, and includes a spindle having permanent magnets at at least two locations in the axial direction, and an outer surface of the permanent magnets at a position facing the permanent magnets. A radial bearing made of permanent magnets arranged with a required gap,
In the magnetic bearing device having a thrust receiving part supporting an end of the spindle, a pressure sensor for detecting an axial load is provided in the thrust receiving part on at least one side of the spindle, and the thrust receiving part is arranged in the axial direction. An actuator made of a piezoelectric element or the like that causes minute displacement is disposed between the pressure sensor and the actuator, and detects when the detected amount from the pressure sensor exceeds a set value by a certain amount. The present invention is characterized in that a control unit is provided that controls the actuator to return the pressure in the thrust receiving portion to a predetermined value.

(Function) When the amount detected by the pressure sensor that detects the axial load on the spindle exceeds a certain amount, a signal from the control unit activates the actuator to slightly displace the thrust receiver to maintain the pressure in the thrust receiver at a specified level. It is supposed to be returned.

(Example) 1 is a spindle, 2 is a magnetic pole that is provided at two locations in the axial direction of the spindle 1, and is made of disk-shaped permanent magnets each having the same diameter as the outer diameter of the spindle 1 and is magnetized in the axial direction. 3 is not shown in the figure. A ring-shaped permanent magnet is attached to a fixed part that is not attached to the magnetic pole 2 and is arranged with a certain gap around the outer periphery of the magnetic pole 2, and the surface facing the magnetic pole 2 is magnetized in the same direction. The magnetic poles 2 and 3 are kept in a non-contact state, for example, by magnetic repulsion. 4 is a ceramic ball protruding from both end faces of the spindle 1, 5 is a thrust receiving plate made of a hard material with which the ceramic ball 4 comes into contact, 6 is a pressure sensor consisting of a strain gauge, etc., and 7 is a piezoelectric element. An actuator that performs minute displacement, such as a VCM; 8 is a housing to which the actuator is attached; 9 compares the amount detected by the sensor with the initially set axial load; and when an axial load of a certain amount or more is applied, the actuator 7 is driven. This is a control unit that performs control so that the

Next, the operation will be explained according to the flowchart for the axial load control subroutine shown in FIG. first,
Turn on the system and set the initial value (reference value) F0 of the axial load in advance. Next, when the spindle 1 is driven to rotate and an axial load Fx is applied to the spindle 1, the pressure sensor 6 detects the actual measurement value Fx and sends a detection signal to the control section 9. The control unit 9 sets the axial load Fx based on this signal and the axial load F of a certain amount initially set. When an axial load of a certain amount or more is detected, the actuator 7 is moved by the detection signal. Subsequently, the axial load Fx is measured again by the pressure sensor 6, and the actuator 7 is activated until the measured value Fx becomes equal to or less than the set value Fll, thereby slightly displacing the spindle 1 by a certain amount to return it to its original position. Therefore, the contact pressure between the thrust receiving plate 5 and the ceramic balls 4 becomes a minimum value, and the amount of wear on the thrust receiving plate 5 is minimized.

Although the above embodiment is a magnetic bearing device in which both ends of the spindle 1 are received by the thrust receiving portion, the present invention is not limited to this, and only one end portion of the spindle 1 is provided to the thrust receiving portion. It is also applicable to magnetic bearing devices supported by (Effects) According to the present invention, a radial spindle comprising a spindle having permanent magnets at at least two locations in the axial direction, and a permanent magnet placed at a position facing the permanent magnet with a required gap from the outer surface of the permanent magnet. In a magnetic bearing device having a bearing and a thrust bearing part supporting an end of the spindle, the thrust bearing part on at least one side of the spindle includes a pressure sensor for detecting an axial load, and the thrust bearing part. An actuator made of a piezoelectric element or the like that causes slight displacement in the axial direction is disposed between the pressure sensor and the actuator, and detects that the detected amount from the pressure sensor exceeds a set value by a certain amount, and the actuator The sensor detects when the axial load exceeds a certain amount, and the control section returns the spindle to bring the axial load within a certain amount. Therefore, wear on the thrust receiving plate can be minimized. This minimizes the relative displacement in the axial direction between the magnetic poles of the spindle and the radial bearing, without reducing the radial load resistance.
Spindle rotation accuracy can be maintained at high accuracy. Furthermore, since the axial load is reduced, a spindle with low torque can be provided. Furthermore, since the amount of wear on the thrust receiving plate can be minimized, the amount of abrasion powder generated can be kept to a minimum, and it can also be used as a spindle for vacuum equipment that requires high cleanliness.

[Brief explanation of drawings]

FIG. 1 is a front view of an embodiment of the present invention, and FIG. 2 is a flowchart of the axial load control subroutine of the present invention. 1... Spindle 2... Magnetic pole of spindle 3... Magnetic pole of radial bearing 4... Ceramic ball 5... Thrust receiving plate 6... Pressure sensor 7...
・Actuator 8... Housing 9... Control section

Claims (1)

[Claims] A radial bearing consisting of a spindle having permanent magnets at at least two locations in the axial direction, a permanent magnet placed at a position facing the permanent magnet with a required gap from the outer surface of the permanent magnet, and an end portion of the spindle. In a magnetic bearing device having a supporting thrust receiving part, the thrust receiving part on at least one side of the spindle includes a pressure sensor for detecting an axial load, a piezoelectric element, etc. for slightly displacing the thrust receiving part in the axial direction. An actuator consisting of a A spindle support device for a magnetic bearing device, which is provided with a control unit that controls to return to a predetermined value.