JPS6311387Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a foil bearing, and in particular, a gas film pressure relief part is provided discontinuously in the circumferential direction at at least one location in the axial width of the flexible metal thin film of the foil bearing. By providing this, the load capacity and rigidity for moment loads are increased, and
This prevents contact between the metal thin film and the rotating shaft.

Conventionally, radial gas bearings have a structure in which the rotating shaft is surrounded by a flexible thin film of metal such as aluminum or stainless steel, and the rotating shaft is supported by the gas film pressure generated between the rotating shaft and the rotating shaft. bearings are used. When the moment load applied is relatively small, this foil bearing can be used to
Sufficient load capacity can be obtained even if supported by multiple foil bearings, but if the load capacity for moment load is insufficient with just one foil bearing,
The axial width of the metal thin film is divided to support the rotating shaft as two or more independent foil bearings.

However, when a rotating shaft is supported by two or more foil bearings, it is difficult to assemble each foil bearing with the same precision, and the metal thin film of one foil bearing and that of the other foil bearing are difficult to assemble. If a misalignment occurs in the positional relationship between the metal thin film and the rotation axis, a portion that comes into contact with the rotation axis will be formed because the metal thin film has rigidity.
For this reason, it is not possible to maintain a completely non-contact state between the rotating shaft and the metal thin film, which becomes a factor that prevents high-speed rotation of the rotating shaft.

In addition, when a foil bearing is divided, the axial width of the metal thin film becomes smaller than when a single foil bearing is used, so when a moment load is applied,
There is a problem that the strength against torsional deformation of the metal thin film is insufficient and the rigidity becomes weak.

This invention was made in order to solve the above problem, and the purpose of this invention is to provide a foil bearing that has high moment load capacity and excellent rigidity. The purpose of this is to provide a foil bearing that maintains complete non-contact with the rotating shaft.

That is, as shown in the embodiments and drawings described below, this invention surrounds the rotating shaft 10 with a flexible metal thin film 12, and the gas film formed between the metal thin film 12 and the rotating shaft 10 is Rotating axis 1
0, in which a gas film pressure escape portion 25 is provided discontinuously along the circumferential direction at at least one location in the axial width of the metal thin film 12. .

Examples of this invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of this invention.

This figure shows a so-called tension-type foil bearing, which is surrounded by a single flexible metal thin film 12 surrounding the rotating shaft 10, and this metal thin film 12 is covered with two axially parallel foil bearings. The metal thin film 12 is wound around a first guide member 17 and a second guide member 18, each consisting of a guide pin 15 and one support pin 16.
Both ends 13 and 14 of the third guide member 19 are passed between the guide pins 15 of the third guide member 19 in an overlapping manner, and are fixed under tension by a tension device (not shown).

An elongated hole 20 is provided along the circumferential direction at approximately the center of the axial width of the metal thin film 10 . This hole 20 includes the first guide member 17,
A total of three guide members are formed separately between the second guide member 18 and the third guide member 19,
Each hole 20 is divided in the same circumferential direction and is discontinuous.

In the foil bearing configured as described above, when the rotating shaft 10 rotates, the metal thin film 12 and the rotating shaft 10 are connected to each other.
Since lubricating gas such as air sucked into the bearing gap between the bearings flows out from the holes 20 of the metal thin film 12, no gas film pressure is generated at the positions of the holes 20, and the holes 20 However, it functions as a relief part 25 for gas film pressure.

Therefore, this foil bearing has a metal thin film 1
2 has two metal thin films 12 with the hole 20 as a boundary.
The bearing has the same structure and function as a foil bearing divided into parts a and 12b.

In this way, in the foil bearing having the above structure, gas films having separate pressure distributions are formed by the metal thin films 12a and 12b on both the left and right sides of the hole 20, and the rotating shaft 10 is supported at two points. Therefore, compared to the original foil bearing which is supported at one point by an undivided metal thin film, the load capacity against a moment load is increased.

In addition, the foil bearing of this invention has a metal thin film 1
0 holes 20 are formed discontinuously in the circumferential direction,
Since the metal thin films 12a and 12b on both the left and right sides of the hole 20 are integral, there is no misalignment between the metal thin films 12a and 12b on both the left and right sides when they are assembled to the rotating shaft 10. . Therefore, the rotating shaft 10 and the metal thin film 12
The bearing clearance between a and 12b is kept constant,
Since the rotating shaft 10 can be maintained in a completely non-contact state, performance will not deteriorate even if the rotating shaft 10 rotates at high speed.

Furthermore, metal thin films 12 on both the left and right sides of the hole 20
Since a and 12b are integrated, the strength against torsional deformation of the metal thin films 12a and 12b is greater than when the metal thin films are divided into separate parts.
Rigidity against moment loads also increases.

FIG. 2 shows another embodiment of this invention, in which a gas film pressure relief part 25 formed between the metal thin film 12 and the rotating shaft 10 is provided at an appropriate interval in the circumferential direction of the metal thin film 12. A plurality of holes 2 are arranged in a dotted manner.
1 was formed.

FIG. 3 shows still another embodiment of this invention, in which a metal thin film 1 is used as a relief part 25 for gas film pressure.
2, mountain-shaped raised portions 22 are formed discontinuously in the circumferential direction. Both lengthwise ends of the raised portion 22 may be closed ends to reduce pressure, but are preferably opened.

In the embodiments shown in FIGS. 1 to 3, the gas film pressure relief portion 25 is provided at one location approximately at the center of the metal thin film 12. However, the gas film pressure relief portion 25 is provided at one location. However, it can be provided at multiple locations as needed.

Furthermore, in the above embodiment, the case where this invention is applied to a tension type foil bearing was explained.
This invention can be applied not only to tension type foil bearings but also to multileaf type, hydroresil type, multi-ring type, and other types of foil bearings.

Furthermore, in the above embodiment, the one-point supported foil bearing is replaced with a two-point supported foil bearing, but the two-point supported foil bearing may also be replaced with a two-point supported foil bearing having the same structure as this invention. Can be applied.

As is clear from the above explanation, this invention has a structure in which a gas film pressure relief part is provided discontinuously in the circumferential direction at at least one location in the axial width of the flexible metal film of the foil bearing. It is said that Therefore, according to this invention, unlike independent foil bearings in which the metal thin film is divided into separate parts, it is possible to prevent contact between the metal thin film and the rotating shaft due to misalignment during assembly to the rotating shaft. Not only is this possible, but the load capacity for moment loads is equivalent to multiple independent foil bearings.
Since the rigidity against moment loads is stronger than that of a plurality of independent foil bearings, the foil bearing is most suitable as a gas bearing for high-speed rotation.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an embodiment of this invention, Fig. 2 is a perspective view showing another embodiment of this invention, and Fig. 3 is a perspective view showing still another embodiment of this invention. be. In the figure, 10 is a rotating shaft, 12 is a metal thin film, 20,
21 is a hole, 22 is a raised portion, and 25 is a relief portion for gas film pressure.

Claims (1)

[Claims for Utility Model Registration] (1) In a foil bearing in which a rotating shaft is surrounded by a flexible metal thin film and the rotating shaft is supported by a gas film formed between the metal thin film and the rotating shaft. , at least 1 of the axial width of the metal thin film
A foil bearing characterized in that a gas film pressure relief part is provided discontinuously along the middle circumferential direction of a portion. (2) The foil bearing according to claim 1, wherein the gas film pressure escape portion is an elongated hole. (3) The foil bearing according to claim 1, wherein the gas film pressure relief portion is a plurality of holes spaced apart in a dotted manner. (4) The foil bearing according to claim 1, wherein the gas film pressure relief portion is a mountain-shaped raised portion.