JPS585521A - Foil journal bearing - Google Patents

Abstract

PURPOSE:To easily control a preload by disposing a plurality of elastic foils in a housing in such a manner that the foils overlap one another at both ends thereof, and the overlapping portions are elastically supported on the housing. CONSTITUTION:An elastic foil 51 is secured to a bearing housing 4 at a fixed leg portions 5S1 thereof, both end portions being placed on the end portions of adjoining elastic foils 52 and 54. The overlapping portions are elastically supported on the bearing housing 4 by elastic supports 61, 64. In this case, each elasticity of foil elastic supports 61-64 determines each contact pressure of the elastic foils 51-54 to a shaft 2. Accordingly, the foil elastic supports 61-64 are selected from viewpoint of load capcity so as to set a desired preload.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a foil journal bearing using foils.

Foil journal bearings have a plurality of thin elastic foils installed in the housing for the journal bearing, which are placed in correspondence with each other on one side of the shaft. This is a dynamic pressure gas bearing that supports the shaft in a floating manner by increasing the pressure (dynamic pressure) in the wedge-shaped cavity. Since this bearing is non-contact, it can be used to support high-speed rotating bodies without causing seizure, and is used as bearings for lightweight rotating bodies such as air machines such as expansion turbines.

Normally when used in an expansion turbine, gas from a compressor (process gas 'A) is introduced or actively fed into this bearing to increase the density of the gas in the wedge-shaped cavity and make the pressure increase effective. .

Conventionally, various types of foil journal bearings have been put into practical use, but in most of them, a single stack of foils is interposed between the inner circumferential surface of the bearing housing and the circumferential surface of the shaft. Dynamic pressure can be generated by simply adjusting the preload, but adjusting the preload is difficult. Therefore, it is necessary to manufacture bearings corresponding to the load capacity, which is inconvenient and also has a complicated structure.

The present invention provides a foil journal bearing that eliminates the drawbacks of the conventional foil journal bearing.

A feature of the 7-oil journal bearing of the present invention is that the main elastic foil of the bearing is a T-shaped foil having foils extending on both sides in the circumferential direction from the fixed installation part on the bearing housing. Several elastic foils are fixedly installed on the bearing housing, and their surfaces correspond to the circumference of the shaft to form a dynamic pressure generating section.

Another feature of the present invention is that when the plurality of elastic foils are installed in the bearing housing, the tips of the foils on both sides are overlapped with each other to form an elastic support that elastically supports the portion in parentheses with respect to the bearing housing. The main point is that it is easy to install and adjust the preload.

The illustrated embodiment will be described in detail below.

FIG. 1 is a perspective view showing the general structure of an air machine, such as an expansion turbine machine. Reference numeral 2 denotes a support shaft (rotating shaft) of the lightweight rotating body 1, which is rotatably supported by a journal bearing 3.

Fig. 2 is a cross-sectional view perpendicular to the axial direction of the foil or journal bearing 3, and 4 is a bearing housing that forms the base of this journal bearing, which is fixedly installed on a bearing support stand (not shown) of the air machine and is attached to the rotating shaft. 2 is rotatably supported.

Elastic foils 51 to 54 are the main components of the journal bearing 3. As typically shown in FIG. 3A, the elastic foil 51 is fixedly installed on the inner peripheral surface of the bearing housing at a fixed leg portion 58. It has a shaft 2 on both sides in the circumferential direction.
An elastic foil 51' corresponding to the circumferential surface of each is formed.

The elastic foils 51 to 54 are arranged at intervals of 90° around the shaft 2, and fixed to the fixing grooves 4 formed in the fixed legs 584 to 5B, 15≦bearing housing 4, respectively. . The lengths of the foils on both sides of each of the elastic 7 oils 51 to 54 are set to such an extent that their tips overlap with the other 7 oils.

The manner of this superposition is determined by the direction of rotation of the shaft 2.

In the illustrated example, since the shaft 2 rotates in the direction of the arrow, the left side foil of one elastic foil A151 is outward from the 7 oil of the other elastic foil 54, and the right side foil is the foil of the other elastic foil 52. It is placed one piece further inward. The length of the overlapping portion is determined in consideration of the size and position of the elastic support, which will be described later.

Although the number of each of the elastic foils 51 to 54 is not limited to four, each of the elastic foils 51 to 54 may overlap each other to form a wedge-shaped cavity corresponding to the aspect of the shaft 2, thereby functioning as a hydrodynamic gas bearing.61 to 64 An elastic support member elastically supports the overlapping portions of the elastic foils 51 to 54 with respect to the bearing housing 4, and an example of its configuration is shown in FIG. 3B.

A coiled pad can also be used as the elastic support.

The foil-like elastic supports 61 to 64 are arranged in the same number as the overlapped portions of the elastic foils, and in the illustrated example, the elastic foils 51
~54 and is installed 45 degrees out of phase.

The foil-like elastic supports 61 to 64 are installed in the bearing housing 4, as shown in FIG.
This is done by inserting it into M, ~4M4.

FIG. 2 shows the assembled state in which the elastic foils 51 to 54 and the foil-like elastic supports 61 to 64 are inserted between the bearing housing 4 and the shaft 2. In this case, the elastic foil 51 is
The contact force (preload) to the shaft 2 of ~54 is set. Therefore, a desired preload can be set by selecting the foil-like elastic supports 61 to 64 based on the load capacity, that is, the capacity of the rotating body 1.

In addition to the embodiments described above, the present invention can be modified in various ways. In the illustrated example, the number of elastic foils installed is four, but this can also be five or six, and in the case of a small diameter shaft, it can be three. Although each elastic foil is formed to extend from the fixed leg on both sides, the left and right lengths can also be made different. Further, in the illustrated example, the fixed leg portion and the material of the oil 7 are shown as being integrated, or they may be made into separate members and connected by welding or the like.

Modifications similar to those described above are also possible for the elastic support. Furthermore, the elastic foil and the elastic support can also be constructed in one piece. In this case, the elastic support that abuts on the outside of the elastic foil is integrally attached to the foil. Furthermore, it is also possible to configure several elastic supports by arranging them as members divided in the axial direction.

In this specification, the term "journal bearing" should be understood as a synonym for radial bearing, and the presence or absence of the journal member itself does not matter. Thrust bearings are not included.

According to the present invention, compared to the conventional 7-oil journal bearing, it is easier to adjust the bleed and respond to the load volume, and the performance of the hydrodynamic gas bearing is improved, making it ideal as a high-speed rotation bearing. It can improve the reliability of air machines such as expansion turbines. In addition, since the foil itself does not require high precision, it can be mass-produced.

[Brief explanation of drawings]

Fig. 1 is a perspective view schematically showing the external appearance of an air machine in which a foil journal bearing is used, Fig. 2 is a sectional view perpendicular to the axis of an embodiment of the present invention, and Fig. 3A is an elastic foil journal bearing. FIG. 3B is an external view of the elastic support. 1...Rotating body, 2...Rotating shaft, 3...OA7 oil journal bearing, 4...e bearing housing, 4Kl~4 in 4.4411~4M4@...fixing groove, 51
~54...9 elastic foil, 51'@ψ and foil, 581-584... fixed leg portion, 61-64... elastic support body, 68, ~6B4,... and fixed leg portion.

Claims (1)

[Claims] A plurality of elastic foils having foils corresponding to the shaft peripheral surface are installed on both sides of the fixed installation part in the circumferential direction of the bearing housing in one run on the inner peripheral surface of the bearing housing so that the tips of the foils on both sides overlap each other. A foil number journal bearing, further comprising an elastic support that elastically supports the overlapping portion of the foils with respect to the bearing housing.