JPH0842569A - Bearing device - Google Patents

Abstract

PURPOSE:To provide a non-contact type bearing device which is constituted to facilitate the processing a assembly works and reduce the cost without lowering the movement precision. CONSTITUTION:A bearing member 2 is positioned facing the outer surface of a shaft member 1 with a bearing gap therebetween. One magnet 11 arranged on the outer surface of the shaft member 1 is positioned opposite to the other magnet 12 arranged at a bearing member 2 to form a repulsion type magnetic bearing. Meanwhile, compressed gas is injected in the bearing gap through a feed hole 2 formed in the bearing member 2 to form a static pressure gas bearing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid type bearing device in which a magnetic repulsion type magnetic bearing is incorporated in a static pressure gas bearing.

[0002]

2. Description of the Related Art As conventional static pressure gas bearings, those shown in FIGS. 6 to 8 are known. In this structure, a bearing member 2 which is a movable body is opposed to an outer surface of a shaft member 1 which is a fixed body through a bearing clearance S. An air supply hole 3 is provided inside the bearing member 2, and the air supply hole 3 is formed in a throttle member (a porous material in the illustrated example) 4 attached to each of the upper, lower, left and right surfaces of the inner surface of the bearing member 2. It is in communication. The porous material 4 functions as a throttle, and the compressed gas is ejected from the air supply hole 3 through the porous material 4 into the bearing gap S to form a fluid film, so that the bearing member 2 does not contact the shaft member 2. It is supported by 1.

In the above conventional example, the compressed gas supply port 5 is provided in the bearing member 2, and the compressed gas pipe is connected to the compressed gas supply port 5 to supply the compressed gas to the air supply hole 3.

[0004]

However, in the above-mentioned conventional hydrostatic gas bearing device, the bearing member 2 is formed only by the fluid film formed in the very small bearing clearance S between the shaft member 1 and the bearing member 2. In order to levitate and support the shaft member 1 in a non-contact manner with respect to the shaft member 1, high processing accuracy is required for processing each component of the bearing device. In addition, when assembling each component, high assembly technology is required. Therefore, there is a problem that the bearing component becomes very expensive, the assembly work takes a lot of time, and the manufacturing is not easy.

Therefore, the present invention has been made in view of the above-mentioned problems of the prior art, and adds the function of a magnetic bearing for supporting in a non-contact manner by utilizing the magnetic repulsive force of a magnet to a static pressure gas bearing. The purpose of this is to provide a bearing device that can always maintain an appropriate bearing clearance by assisting with the magnetic repulsion force of the magnetic bearing when the precision of the gas bearing part deteriorates somewhat and it is difficult to maintain a stable bearing clearance. There is.

[0006]

According to the present invention, a bearing member faces the outer surface of a shaft member through a bearing clearance, and one magnet provided on the outer surface of the shaft member faces the other magnet provided on the bearing member. And a repulsive magnetic bearing, and a static pressure gas bearing is formed by ejecting compressed gas from the air supply hole provided in the bearing member into the bearing clearance.

[0007]

In the bearing device of the present invention, the fluid film formed by ejecting the compressed gas through the throttle into the bearing clearance between the shaft member and the bearing member becomes nonuniform and unstable, When the bearing member tilts with respect to the shaft member and some of them are about to come into contact,
The action of the magnetic bearing increases the magnetic repulsion force and expands the bearing clearance. This magnetic repulsive force increases in inverse proportion to the square of the gap (bearing clearance) between the opposed magnets, and acts to maintain the bearing clearance at an appropriate size.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 show an embodiment of the present invention in which a magnetic bearing is incorporated in a porous static pressure direct acting gas bearing. The same or corresponding parts as in the conventional case are designated by the same reference numerals.

First, the structure will be described. One of the bearing surfaces 1a is a flat outer surface, that is, a side surface of the shaft member 1 which is a prismatic fixed body in the vertical and horizontal directions. The shaft member 1 is provided with arcuate recesses 10 axially cut out at positions between adjacent side surfaces, that is, at four corners (ridges) in the axial direction. An arc magnet (also called a segment magnet) is provided in the arc-shaped recess 10.
11 is fixedly attached over the entire length of the shaft member 1. Each segment-shaped magnet 11 is magnetized so that its arcuate end surface has an N pole and an S pole, respectively.

On the other hand, on the inner surface of the square frame-shaped bearing member 2 fitted in the shaft member 1 via the bearing clearance S so as to be movable in the axial direction, as shown in FIG. The pair of elongated bar-shaped magnets 12 facing the magnetic poles are arranged at the four corners. In this way, a pair of magnetic bearings is formed by the combination of one segment magnet 11 and two opposing magnets 12. The magnetic poles of the opposing magnets 12 are of a polarity that repels the magnetic poles of the segment magnets 11 and forms an air gap G between the bearing member 2 and the shaft member 1.

On each of the upper, lower, left and right sides of the inner surface of the bearing member 2,
Further, a porous material 4 as a throttle member is embedded and arranged, and the surface of the porous material 4 constitutes the other bearing surface 2a. Then, the compressed gas supplied from the compressed gas supply port 5 provided on the outer surface of the bearing member 2 is supplied to each porous material 4 through the air supply holes 3 provided inside the bearing member 2 The static pressure direct-acting gas bearing is constructed.

In the case of this embodiment, the machining accuracy such as straightness, flatness, parallelism, squareness, coaxiality, and the like regarding the bearing surface 1a of the shaft member 1 and the bearing surface 2a of the bearing member 2 are However, the accuracy does not have to be as high as required in a normal static pressure gas bearing. Next, the operation will be described. In the case of this bearing device, the action of the static pressure gas bearing that floats and supports the bearing member 2 with respect to the shaft member 1 using the fluid film is supplemented by the magnetic repulsion force of the magnetic bearing that uses the magnetic force.

That is, the compressed air supplied from the compressed air supply source (not shown) to the compressed gas supply port 5 of the bearing member 2 is supplied to the respective porous materials 4 through the air supply holes 3 and inside the porous material 4. Bearing surface 2a after being squeezed to an appropriate pressure through the fine pores of
From the bearing to the bearing gap S to form a fluid film to support the bearing member 2 in a non-contact manner by floating. If the bearing member 2 is moved in the axial direction in this state, the bearing member 2 moves extremely smoothly along the shaft member 1 without any sliding resistance. At this time, the bearing clearance S maintained between the shaft member 1 and the bearing member 2 usually has a frame shape with a uniform width as schematically shown in FIG.

However, the bearing surface 1 of the shaft member 1 and the bearing member 2
When the machining accuracy of a and 2a is not as high as the normal machining accuracy (or even when the machining accuracy is a normal high accuracy, or when an eccentric load from the outside acts on the bearing member 2), the bearing clearance S is As shown in FIG. 5, it changes relatively and becomes non-uniform. Then, in each magnetic circuit, a large or small difference occurs in the air gap G between the different poles. Magnetism acting between magnetic poles (repulsion)
Since the force is inversely proportional to the square of the air gap G, for example, in the case of FIG. 5, the magnetic forces Fa, Fg, Fe, Fc are Fb,
It becomes larger than each magnetic force of Fh, Ff, Fd. The difference between the magnetic forces functions as a moment in the recovery direction, the relative inclination between the shaft member 1 and the bearing member 2 is corrected, and the non-uniform bearing clearance S is recovered to a uniform one as shown in FIG. .

Thus, according to this embodiment, even if the bearing clearance S between the shaft member 1 and the bearing member 2 becomes non-uniform, the magnetic repulsive force between the opposing magnetic poles of the magnetic bearing causes the air gap G, that is, the magnetic gap. Since the bearing clearance S acts in a uniform direction, the machining accuracy of the components of the bearing device does not need to be as high as in the conventional case, and the machining cost can be reduced accordingly. Further, even when assembling the bearing device, it is not necessary to repeat thorough precision inspection, and the assembling work time can be shortened. As a result, it is possible to provide a bearing device that is inexpensive and easy to assemble while ensuring high precision motion accuracy. There is also an advantage that a static bearing device with high rigidity can be obtained by incorporating the magnetic bearing.

In the above embodiment, the linear bearing device in which the bearing member moves along the shaft has been described. However, the shaft is a moving member and the bearing member is a fixed member. The present invention can be applied to bearings and thrust bearings. Further, although the diaphragm member for the static pressure gas bearing is shown to use the porous material 4, it is not limited to this, and a diaphragm member of other type such as an orifice diaphragm, a self-made diaphragm or a surface diaphragm is used. It is also applicable to.

[0017]

As described above, according to the bearing device of the present invention, the bearing member faces the shaft member through the bearing clearance, and the compressed gas is ejected from the air supply hole provided in the bearing member into the bearing clearance. By forming a fluid film to form a static pressure gas bearing that supports both members in a non-contact manner, one magnet is provided on the outer surface of the shaft member, and the other magnet that opposes and opposes the bearing member is provided. Since the magnetic bearing is provided, the fluid film in the bearing clearance becomes nonuniform and the bearing member and the shaft member are relatively inclined, and the magnetic repulsive force of the magnetic bearing acts to restore the inclination. With the addition of this magnetic restoration function, it is not necessary to maintain the machining accuracy and assembly accuracy of the components of the hydrostatic bearing at high accuracy, and as a result, a bearing device with high motion accuracy can be provided at low cost. Is obtained.

[Brief description of drawings]

FIG. 1 is a plan view of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is an enlarged view of a part III in FIG.

FIG. 4 is an operation explanatory view (normal state) of the one shown in FIG.

FIG. 5 is a diagram for explaining the operation of the one shown in FIG. 1 (at the time of abnormal operation).

FIG. 6 is a plan view of a conventional hydrostatic bearing device.

7 is a sectional view taken along line VII-VII of FIG.

8 is an enlarged view of part VIII in FIG. 7.

[Explanation of symbols]

 1 Shaft member 2 Bearing member S Bearing clearance 3 Air supply hole 11 One magnet 12 The other magnet

Claims (1)

[Claims] 1. A repulsion-type magnetic bearing, wherein a bearing member faces the outer surface of the shaft member with a bearing clearance therebetween, and one magnet provided on the outer surface of the shaft member faces the other magnet provided on the bearing member. A bearing device configured to form a static pressure gas bearing by injecting compressed gas from a supply hole provided in the bearing member into a bearing clearance.