JPS5847571B2 - Hydrostatic bearing device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a hydrostatic gas bearing device.

BACKGROUND ART A self-drawn type static pressure gas bearing that has been widely used in the past is shown in FIGS. 1 and 2.

In both figures, 1' is the bearing body, 2'' is the sliding surface, and 3' is the bearing body.
is an air supply hole, and 4' is a 01J groove.

This bearing supplies pressurized gas to the air supply hole 3', and although not shown, hydrostatic film pressure is generated in the bearing gap created between the bearing and the shaft, thereby preventing contact with the shaft. It is something to do.

The characteristics of stationary bearings are that when Calorie pressure gas is supplied from the outside, a film is formed regardless of the rotation of the shaft, preventing contact with the shaft, resulting in a semi-permanent life, and reducing friction torque during rotation. It can be extremely small.

However, the static pressure bearings shown in Figs. 1 and 2 are so-called full-circumference bearings in which the entire inner circumference slides on the shaft.
rnal bearing), the rotation of the shaft increases and hydrodynamic pressure is applied within the bearing gap.
When this becomes large enough, whirling occurs.

This poses a major problem when this type of bearing is put into practical use.

In order to prevent this, a so-called elastic support method has been adopted in which an elastic member such as a 01J ring is inserted into the 4' portion of Fig. 1 to support the entire bearing body 1' with a degree of freedom in the radial direction. Although it is not sufficient, it has had some effect.

On the other hand, FIGS. 3 and 4 show tilting pad type bearings that are said to be extremely stable against whirling.

Note that FIG. 4 is a sectional view taken along the line BB in FIG. 3.

1" is the pad, 2'' is the pivot, 3" is the shaft body, 4
” is the adjustable pivot for the top pad, and 5” is the set screw for the top pivot.

This bearing is a hydrodynamic bearing that generates film pressure as the shaft rotates, thereby preventing pad 1" from coming into contact with the shaft. If the rotation is not high enough, pad 1" and the shaft will come into contact. .

In order to prevent this, the structure becomes complicated, but sometimes a preliminary air supply hole is provided through the pivot 2'' and pressurized gas is sent from the outside to lift it up.

The purpose of the tilting pad bearing is to integrate the hydrodynamic pressure generated on the sliding surface of pad 1", since pad 1" can rotate around pivot 2", albeit within a limited range. The point of application of the resulting force is above the pivot 2'' and at the same time its direction is toward the center of the shaft, so it is at a point that does not produce any whirling force on the shaft.

However, since the tilting pad bearing is a hydrodynamic bearing, even if the rotation of the shaft is considerably high, the film pressure is small and the film rigidity is small.

Those with a structure in which high-pressure gas is supplied from the outside at the time of starting and stopping have a complicated structure, while tilting pad bearings have the drawback of strict requirements for dimensional accuracy.

As mentioned above, hydrostatic bearings have problems with whirling stability during high-speed rotation, and tilting pad bearings have a small load capacity and strict requirements for dimensional accuracy. Although there is a method of supplying high-pressure gas and utilizing the static pressure effect, the structure becomes complicated and it becomes difficult to ensure dimensional accuracy.

The purpose of the present invention is to focus on the above points, simplify the structure, and provide a bearing that has both the stability of a tilting pad bearing and the load capacity of a hydrostatic bearing. While the tilting pad bearing has pads arranged in the circumferential direction, the bearing of the present invention is divided in the axial direction and has ring-shaped bearings arranged, so that one tilting pad can be used with one ring-shaped bearing. This was done so that the effect of the amount of water could be reduced.

As a result, the structure is relatively simple, the accuracy of the bearing inner diameter corresponding to the curvature of the pad can be easily ensured, and the so-called static pressure effect of supplying high-pressure gas from the outside can be easily utilized.

The present invention can be widely applied to helium circulators, gas expansion turbines, high-speed rotation gas compressors, high-speed rotation compressors (small Freon turbine compressors, etc.), and the like.

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

FIG. 5 is a sectional view showing a hydrostatic bearing device according to an embodiment of the present invention, FIG. 6 is a sectional view taken along the line A--A in FIG. 5, and FIG. 7 is a sectional view showing each bearing.

In the figure, 1, 2.3 are bearings, 4 is a bearing case, and 5 is a bearing case.
is the cover, and 6 is the 0 1J between the bearing case 4 and the cover 5.
7 is an air supply hole, 8 is a spring, 9 is a pressurized air supply hole,
10 is a seat hole of the spring 8, 11 is an exhaust groove provided on the sliding surface of the bearing, 12 is a rotation stop pin, 13 is a groove, and 14 is a shaft.

As shown in Figure 7, three ring-shaped bearings 1, 2, 3
Air supply hole 7, spring seat hole 10, and exhaust groove 11 are installed in 12.
The three bearings 1, 2, and 3 are formed with a phase shift of 0°, and as shown in Figs. Incorporate.

Since the tip of the locking pin 12 fitted into each bearing 1, 2.3 is inserted into a common long groove 13 formed in the axial direction in the bearing case 4, the rotation pin 12 can be inserted into the bearing 1, 2 even during operation. .3
The relative positions of the air supply hole 7 and the spring 8 of the bearing 2 do not change.
The relationship between the diameter of the pin 12 and the width of the groove 13 is adjusted to the extent that displacement of the pins 12 in the radial direction, that is, in the opposite direction by the springs 8 of the pins 12 is permitted.

The bearings 1, 2, and 3 are provided with one or more air supply holes 7 in any number.

However, the air supply holes 7 are not necessarily provided at equal pitches all around the circumference, but may be provided biased toward the direction of the spring 8 as in this embodiment.

The functions and effects of the above structure will be described.

When externally pressurized gas is sent through the supply hole 9 of the bearing case 4, it flows to the outer periphery of each bearing L2, 3, and then flows through the air supply hole 7 of each bearing 1, 2.3 to the bearing between the bearing surface and the shaft. Flows into the gap.

In the bearing gap, the pressure becomes film pressure and is reduced to atmospheric pressure, but a spring 8 is inserted into each bearing 1, 2.3,
Since the film is pressed in each of the three directions, the film pressure is high where the film has the small thickness of the spring 8, and is low on the opposite side, almost to atmospheric pressure.

Therefore, since the film pressure in the area where the spring 8 is located governs the bearing performance, although the bearings 1 and 2.3 are ring-shaped, each acts similarly to one pad of the tilting pad bearing. become.

The film pressure decreases as the gap with the shaft increases,
As the gap becomes smaller, it becomes larger, and there is rigidity between the bearings 1, 2.3 and the shaft.

Looking at one bearing 1, since the spring 8 is biased in one direction, there is almost no reaction force in the direction perpendicular to the resultant force of the two springs 8, and it cannot receive any force in this direction. .

This means that even if a hydrodynamic force is generated on the bearing 1,
Before applying force to the shaft 14, the bearing 1 is displaced in the same manner as the tilting pad bearing, and no whirling occurs.

Three bearings 1, 2.3 act independently on the shaft 14.

The rigidity of the bearings 1, 2.3 is relatively high because they are hydrostatic bearings, and by making the rigidity of the spring 8 sufficiently smaller than this, the rigidity of the eccentricity of the shaft 14 with respect to the bearing case 4 is almost completely reduced by the spring of the spring 8. is equal to a constant, and the film thickness will hardly change.

This means that the rigidity of the entire bearing depends on the mechanical elasticity of the spring 8, and the cause of complicated whirling due to film pressure is not introduced into the rotating shaft system. It is possible to stably rotate up to a frequency close to the free support natural frequency of 14.

In addition, it was extremely difficult to convert a small diameter bearing into a tilting pad bearing, and also a static pressure bearing that supplies Calorie gas from the outside, due to its complicated structure.
It is easy to make a segmented ring-shaped bearing, and it enables extremely stable high-speed rotation that was not possible with conventional bearings.

Furthermore, by using an elastic member with internal damping, such as rubber, in place of the spring 8, it is possible to suppress vibrations not only from whirling, but also from the natural frequency, allowing extremely high-speed rotation. You can get bearings.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a conventional hydrostatic gas bearing, Fig. 2 is a sectional view taken along the line A-A in Fig. 1, Fig. 3 is a sectional view showing a tilting pad type bearing, and Fig. 4 is a sectional view showing a tilting pad type bearing. 3 is a cross-sectional view taken along the line B-B in FIG. 3, FIG. 5 is a cross-sectional view showing a hydrostatic bearing device according to an embodiment of the present invention, FIG. 6 is a cross-sectional view taken along the line A-A in FIG. 5, and FIG. 5 is a sectional view showing each bearing of the device of FIG. 5. FIG. 1, 2, 3...Bearing, 4...Bearing case, 5...Cover, 6...0 1J ring, 7... Air supply hole, 8... Spring, 9.
... Pressurized gas supply hole, 10 ... Spring 8
seat hole, 11...exhaust groove, 12...stopping pin, 13...groove, 14...shaft.

Claims (1)

[Claims] 1. Multiple ring-shaped bearings built into the bearing case so that they can each be displaced in the radial direction, an air supply hole that passes through the bearings and supplies pressurized gas to the bearing surface, and controls the rotation of the bearings. a detent device, comprising an elastic member disposed on the outer circumferential side of each of the bearings so as to shift its position relative to each of the bearings at approximately equal intervals in the circumferential direction, and biasing each of the bearings toward the opposite side. Hydrostatic bearing device.