JP2684765B2 - Dynamic pressure gas bearing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Objects of the Invention (1) Field of Industrial Application The present invention is used in high-speed rotating machines such as air cycle machines for aircraft, expansion turbines for helium liquefaction devices, and turbochargers for automobiles. The present invention relates to a bearing, and more particularly to a dynamic pressure gas bearing that supports a load by a gas film formed between a fixed member and a rotating member.

(2) Prior Art As a bearing used for a high speed rotating machine, it is formed between a fixed member and a rotating member as shown in, for example, US Pat. No. 3,635,534 (Class 308, 1972 patent). A dynamic pressure gas bearing is known in which a thin gas film is generated between both members by a wedge-shaped space and a load is supported by the lubricating action of this gas film. Such a dynamic pressure gas bearing is applied to a thrust bearing or a journal bearing.

FIG. 14 shows the structure of such a conventional dynamic pressure gas bearing, and each shows a state in which the cross section along the circumference of the load supporting surface is linearly developed.

The first conventional example shown in FIG. 14 (A) is provided with a plurality of support bases 02 fixed at predetermined intervals on a base 01 which is a fixing member, and reinforcing members laminated on the support base 02 in three layers. A plurality of foils 04 formed of a flexible material such as a thin metal plate are fixed to the upper surface of 03. The foil 04 has a free end 04a inclined upward, and a runner 05 as a movable member that faces the upper surface of the foil 04 and rotates in the direction of arrow R.
An initial wedge-shaped space 06 is formed between and.

According to the first conventional example, when the runner 05 rotates in the direction of arrow R, gas is pushed into the initial wedge-shaped space 06, and the runner 05 is supported in a floating state by the pressure of the gas film formed by the initial wedge-shaped space 06. It As a result, the runner 05 is the base 01
It can rotate without touching.

The second conventional example shown in FIG. 14 (B) includes a strip-shaped foil 04 placed on a plurality of support bases 02 provided on the base 01, and a runner 05 is provided near the rear portion of each support base 02. A small recess 04b is formed on the upper surface of the foil 04 facing to.

According to the second conventional example, when the runner 05 rotates in the direction of the arrow R, the foil 04 bends downward in the recess 04b due to the gas pressure acting on the recess 04b. Therefore, a wedge-shaped space is formed between the lowermost point of the bent foil 04 and the top of the subsequent support base 2 and the runner 05, and the runner 05 supported in a floating state by the pressure of the gas film formed in the wedge-shaped space. Can rotate without contact with the base 01.

The third conventional example shown in FIG. 14 (C) is equipped with a large number of minute projections 07 projectingly provided on the upper surface of the base 01, and one end of which is the base.
A strip-shaped foil 04 fixed to 01 is placed on the upper surface of the minute projection 07. The micro-projections 07 are formed so that the height gradually increases along the rotation direction R of the runner 05 at a plurality of locations (for example, three locations) in the circumferential direction, and in this portion, an initial wedge shape is formed between the runner 05 and the foil 04. A space 06 is formed. Therefore, the runner 05 supported in a floating state by the pressure of the gas film formed on the initial wedge-shaped space 06 and on the downstream side (the right side in the drawing) of the initial wedge-shaped space 06 can rotate without contact with the base 01.

(3) Problems to be Solved by the Invention However, in the dynamic pressure gas bearing of the first conventional example, not only is it extremely troublesome to bend the free ends 04a of a large number of fine foils 04 into an inclined state, but also rotation is difficult. There is a problem that the free end 04a of the foil 04 that is in contact with the runner 05 at the start is pressed into a flat state and the initial wedge-shaped space 06 disappears, so that a sufficient pressure increase cannot be obtained.

The dynamic pressure gas bearing of the second conventional example is a foil 04
Since the dent 04b formed in 1 is small, the pressure increase at the start of rotation in this portion is insufficient, and it is difficult to bend the foil 04 until a sufficient wedge-shaped space is formed. If the plate thickness of the foil 04 is set small in order to prevent this, there is a problem that the rigidity of the foil 04 is insufficient and the load capacity is reduced. Further, there is also a problem that the recesses 04b tend to be clogged with foreign matter and lack in durability.

Further, the dynamic pressure gas bearing of the third conventional example is a foil 04
Is bent downward between the minute projections 07 to generate small irregularities, which not only lowers the load capacity, but also causes frictional force to act on almost the entire lower surface of the runner 05 at the time of starting and stopping the rotation to improve durability. There is a problem of decline. Also, since the wedge-shaped space that acts during rotation is only a few initial wedge-shaped spaces 06,
There is a problem that a sufficient load capacity cannot be obtained when the runner 05 tilts and makes a conical movement.

The present invention has been made in view of the above circumstances, and is capable of forming a sufficient gas film at the start of rotation and during rotation, has high durability against clogging of foreign matter and frictional force, and has a load capacity. An object of the present invention is to provide a dynamic pressure gas bearing having a large size.

B. Configuration of the Invention (1) Means for Solving the Problems In order to solve the above problems, the present invention provides a fixing member and a rotating member that face each other with a minute gap therebetween, and these fixing member and the rotating member. In a dynamic pressure gas bearing that supports the load acting between both members due to the pressure of the gas film formed between them,
A plurality of support protrusions arranged at a predetermined interval on the fixing member side, and a flexible member supported by the upper surfaces of the plurality of support protrusions to bridge the support protrusions and one end of which is fixed to the fixing member. And an initial wedge-shaped space formed between the foil and the rotating member in the vicinity of the fixing portion of the foil, and the pressure of the gas introduced from the initial wedge-shaped space into the gap between the rotating member and the foil. Thus, the foil is bent and a plurality of wedge-shaped spaces similar to the initial wedge-shaped space are repeatedly formed between the adjacent support protrusions.

(2) Operation According to the present invention having the above-described configuration, when the gas that is dragged by the viscosity and moves with the rotation of the rotating member is pushed into the initial wedge-shaped space formed between the foil and the foil, The pressure of the gas acts on the upper surface of the foil, causing the foil bridging between adjacent support projections to deflect downward. As a result, the foil bends in a wave shape, and a plurality of wedge-shaped spaces similar to the initial wedge-shaped space are repeatedly formed on the upper surface of the foil. Therefore, a gas film is formed between the foil and the rotating member by the initial wedge-shaped space and the newly formed wedge-shaped spaces, and the rotating member supported in a floating state by the pressure rotates without contacting the foil. can do.

(3) Example Hereinafter, an example in which the dynamic pressure gas bearing of the present invention is applied to a thrust bearing will be described with reference to the drawings. In the respective embodiments, corresponding components are designated by the same reference numerals and overlapping detailed description will be omitted.

1 to 4 show a first embodiment of the present invention.
FIG. 1 is a plan view of the base, which is the fixed member, as seen from the runner side, which is the rotary member, FIG. 2 is a sectional view taken along the line II-II along the circumferential direction of FIG. 1, and FIG. FIG. 4 is a diagram showing the pressure distribution at the start of rotation, and FIG. 4 is a diagram showing the pressure distribution during the rotation.

As shown in FIGS. 1 and 2, the dynamic pressure gas bearing B includes a ring-shaped support base 2 fixed to the surface of a base 1 which is a fixing member. A runner 3 shown in FIG. 2, which is a disk-shaped rotating member, is integrally formed on a rotary shaft (not shown) that penetrates an opening 2a (see FIG. 1) formed in the center of the support base 2. The upper surface of the support base 2 and the lower surface of the runner 3 face each other with a predetermined gap.

A plurality of (8 in this embodiment) support projections 4 having a rectangular cross section are radially formed on the surface of the support base 2. The surface of the support projections 4 is made of a flexible metal thin plate or the like. The formed ring-shaped foil 5 is placed.
This foil 5 is cut in a part of its circumference, and is fixed to the surface of the support base 2 by means such as spot welding at one end thereof. Therefore, the foil 5 located between the welded portion 6 and the adjacent support protrusion 4 is inclined obliquely upward and is tapered between itself and the runner 3 in the rotation direction of the runner 3 (shown by the arrow R). An initial wedge-shaped space 7 is formed.

Next, the operation of the embodiment of the present invention having the above-described configuration will be described.

When the runner 3 starts rotating in the direction of arrow R, the gas contacting the lower surface of the runner 3 is dragged by the viscosity, and starts to move in the direction of arrow R together with the runner 3. The gas that moves with the runner 3 is forcibly pushed into the initial wedge-shaped space 7 formed between the runner 3 and the foil 5, and a thin gas film is formed on the entire upper surface of the foil 5. Immediately after the start of rotation of the runner 3, the foil 5 is in a flat state over the entire circumference, and the pressure of the gas film has a constant distribution shown in FIG. 3A.

After a lapse of time from the start of rotation of the runner 3, the foil 5 pressed by the pressure of the gas film is bent downward between the adjacent support protrusions 4 and is wavy. By this deformation of the foil 5, as shown in FIG. 3 (B), a wedge-shaped space 7a similar to the initial wedge-shaped space 7 is formed at the position in front of each support protrusion 4, and the pressure distribution of the gas film is shown in FIG. 3B. It has an independent high voltage part as shown in. And
This pressure is greatest at the upper part of the support protrusion 4 where the thickness of the gas film is thin, and is large in the support protrusion 4 where the thickness of the gas film is thick.
It becomes smaller in the meantime.

In this way, the runner 3 is supported in a floating state by the gas film formed between the runner 3 and the foil 5, and can be rotated without contacting the foil 5. When the runner 3 tilts with respect to the base 1 and makes a conical movement, the gap between the runner 3 and the foil 5 is partially reduced, and the pressure of the gas film at that portion is increased. This allows
A restoring force is generated in the inclined runner 3 and a stable rotation state is maintained.

4 and 5 show a second embodiment of the present invention.

This embodiment has two semicircular laminates in which a slightly rigid underfoil 8 is superposed on the lower surface of the foil 5. In the two laminated bodies, the foil 5 and the underfoil 8 are welded at the welded portion 6a, and the underfoil 8 and the support base 2 are welded at the welded portion 6b, so that the support base 2 has a ring shape as a whole. Is fastened to.

According to this embodiment, the gas film is quickly formed by the action of the two initial wedge-shaped spaces 7 at the start of the rotation of the runner 3.
By stacking the underfoil 8, the rigidity of the foil 5 can be adjusted. Moreover, since the foil 5 and the underfoil 8 are relatively slippery, they can be easily bent even if the total thickness thereof is increased, and the foil 5 is deformed in a wave shape while the runner 3 is rotated. It does not hinder the action of forming the wedge-shaped space 7.

FIG. 6 shows a third embodiment of the present invention, which is inclined so that the downstream side (the right side in the figure) of the runner 3 in the rotation direction R is higher than the upper part of the support protrusion 4 that abuts on the foil 5. surface
It is characterized in that 4a is formed.

According to this embodiment, the foil 5 is guided by the inclined surface 4a of the support protrusion 4 to regulate the shape of the initial wedge-shaped space 7, and even when the foil 5 is deformed into a wavy shape, the front side of each support protrusion 4 is prevented. A wedge-shaped space 7a having an appropriate inclination angle is formed at the position.

Further, instead of inclining the upper surface of the support protrusion 4 as described above, the front side of the support protrusion 4 is cut out to form a step 4b as in the fourth embodiment shown in FIG. 8
Steps 4b are formed on both sides of the support protrusion 4 as in the fifth embodiment shown in the figure.
May be formed, whereby the same effect as that of the third embodiment can be obtained.

FIG. 9 shows a sixth embodiment of the present invention, which is characterized in that a plurality of auxiliary projections 9 are formed on the lower surface of the support base 2. The auxiliary protrusions 9 are formed so as to be positioned in the middle of the support protrusions 4 formed on the upper surface of the support base 2. When a load is applied to the support protrusions 4, the support bases 2 are moved downward between the adjacent auxiliary protrusions 9. It is designed to bend.

Therefore, when the gap δ formed between the foil 5 and the runner 3 above each support stand projection 4 becomes non-uniform due to manufacturing errors or the like, the pressure of the air film becomes excessive in the portion where the gap δ is small. However, the support protrusions 4 to which this excessive pressure acts sink downward, so that the gap δ increases, and as a result, the gap δ can be made uniform.

FIG. 10 shows a seventh embodiment of the present invention. In this embodiment, the support base 2 has an upper support base 2a having a support protrusion 4.
And the lower support 2b having the auxiliary protrusion 9 has a two-layer structure, and the same effect as that of the sixth embodiment can be obtained.

FIG. 11 shows an eighth embodiment of the present invention. In this embodiment, a plurality of support protrusions 5a are formed on the lower surface of the foil 5, and the support protrusions 5a are brought into contact with the upper surface of the flat plate-shaped support base 2. It has a feature in the point of contact.

According to this embodiment, the fragile foil 5 does not come into direct sliding contact with the support base projection 4, so that the durability thereof can be improved.

FIG. 12 shows a ninth embodiment of the present invention. In this embodiment, a slightly rigid underfoil 8 is laminated on the lower surface of the foil 5, and a support projection 8a is integrally formed on the lower surface of the underfoil 8. It was formed.

According to this embodiment, the same effect as that of the second embodiment can be obtained.

FIG. 13 shows a tenth embodiment of the present invention, which is characterized in that the supporting base 2 is not provided and the supporting protrusion 1a is directly formed on the surface of the base 1.

According to this embodiment, since the support base 2 is omitted, the number of parts is reduced and the structure can be simplified.

As described above, the embodiments of the present invention have been described in detail. However, the present invention is not limited to the above embodiments, and various small design changes can be made without departing from the present invention described in the claims. It is possible to do.

For example, this dynamic pressure gas bearing is not limited to a thrust bearing,
It is also applicable to journal bearings. in this case,
The outer peripheral surface of the rotating shaft is supported by the foil arranged on the inner peripheral surface of the cylindrical fixing member.

Further, the number of divisions of the foil 5 is not limited to one or two in the embodiment, and may be three or more.

Further, the support projection supporting the lower surface of the foil 5 may be biased upward by a spring. With this arrangement, when an excessive load is applied, the spring is compressed and the support projection sinks, The gap δ between the foil 5 and the runner 3 automatically becomes constant, and it becomes possible to obtain a uniform load distribution.

C. Effects of the Invention According to the above-described dynamic pressure gas bearing of the present invention, the initial wedge-shaped space is reliably ensured between the foil and the runner at the start of rotation, so that the gas film can be quickly formed. Further, during rotation, a plurality of wedge-shaped spaces are formed by the deflection of the foil, and a sufficient load capacity can be obtained by the gas film formed by the wedge-shaped spaces and the initial wedge-shaped space. Further, since the wedge-shaped space constitutes a large number of independent high-pressure portions on the circumference of the foil, it is possible to obtain a sufficient load capacity with respect to the conical movement of the rotating member. In addition, the sliding area at the start and stop of rotation is small,
Moreover, since there is no groove in which foreign matter is clogged, its durability can be improved.

[Brief description of the drawings]

FIG. 1 is a plan view of a dynamic pressure gas bearing according to a first embodiment of the present invention, FIG. 2 is a sectional view taken along line II-II of FIG. 1, and FIGS. 3 (A) and 3 (B) show the same. FIG. 4 is a plan view of a dynamic pressure gas bearing according to a second embodiment of the present invention, FIG. 5 is a sectional view taken along line VV of FIG. 4, and FIGS. Sectional views showing the third to tenth embodiments of the invention, and FIGS. 14 (A), (B) and (C) are sectional views showing a conventional dynamic pressure gas bearing. 1 ... Base (fixed member), 1a ... Support protrusion, 3 ... Runner (rotating member), 4 ... Support protrusion, 5 ... Foil,
5a ... Support protrusion, 7 ... Initial wedge-shaped space, 7a ... Wedge-shaped space, 8a ... Support protrusion

Claims (1)

(57) [Claims] 1. A dynamic pressure gas in which a fixed member and a rotating member are opposed to each other with a minute gap therebetween, and a load acting between both members is supported by a pressure of a gas film formed between the fixed member and the rotating member. In the bearing, a plurality of support protrusions arranged at a predetermined interval on the side of the fixing member and a bridge between the support protrusions supported by the upper surfaces of the plurality of supporting protrusions and one end of which is fixed to the fixing member. A flexible foil and an initial wedge-shaped space formed between the foil and the rotating member in the vicinity of the fastening portion of the foil, and introduced into the gap between the rotating member and the foil from this initial wedge-shaped space. A dynamic pressure gas bearing, characterized in that the foil bends due to the pressure of the gas to repeatedly form a plurality of wedge-shaped spaces between adjacent support protrusions.