CN-116829845-B - Gas bearing device and turbocharger

CN116829845BCN 116829845 BCN116829845 BCN 116829845BCN-116829845-B

Abstract

A gas bearing device for rotatably supporting a rotary shaft with a gas as a working fluid, the gas bearing device comprising a housing through which the rotary shaft passes, an annular top foil provided inside the housing and surrounding an outer periphery of the rotary shaft, return springs provided between the top foil and the housing and each having a plurality of hills in contact with the top foil and valleys in contact with the housing, and a pair of snap rings fitted into shaft holes through which the rotary shaft passes in the housing, wherein movement of the return springs is regulated in an axial direction of the rotary shaft, and inner peripheral surfaces of the snap rings have self-lubricity.

Inventors

Two rivers are also expensive
Yama Shuuichi
TETSUYA SUZUKI
Bavin field straight way

Assignees

三菱重工发动机和增压器株式会社

Dates

Publication Date: 20260508
Application Date: 20220221
Priority Date: 20210226

Claims (4)

1. A gas bearing device for rotatably supporting a rotary shaft with a gas as a working fluid, the gas bearing device comprising: A housing through which the rotation shaft passes; an annular top foil provided inside the housing and surrounding an outer periphery of the rotation shaft; A return spring provided between the top foil and the housing, the return spring having a plurality of hills in contact with the top foil and valleys in contact with the housing; A pair of snap rings fitted into shaft holes penetrating the rotary shaft of the housing, the movement of the return spring being restricted in the axial direction of the rotary shaft, The pair of snap rings are respectively in a ring shape with a part thereof being cut, are formed in such a way that the outer circumference and the inner circumference are the same center, and are provided with holes for tools at both ends, The pair of snap rings are respectively composed of synthetic resin having self-lubricity, The inner peripheral surfaces of the snap rings are respectively formed by smooth surfaces, The pair of snap rings supports the rotation shaft when the rotation shaft rotates at a low speed, When the rotating shaft rotates at a high speed, an air film is formed between the inner peripheral surfaces of the pair of snap rings and the outer peripheral surface of the rotating shaft in the circumferential direction of the rotating shaft.
2. The gas bearing device according to claim 1, wherein, The return spring is composed of a spring having a lower supporting rigidity at high temperature than at low temperature.
3. A gas bearing device according to claim 2, wherein, The return spring is composed of bimetal formed by bonding two metal plates with different thermal expansion rates.
4. A turbocharger provided with the gas bearing device according to any one of claims 1 to 3.

Description

Gas bearing device and turbocharger Technical Field The present disclosure relates to gas bearing devices and turbochargers. Real desire claims priority based on 26 th month 2021 from Japanese patent office, japanese patent application No. 2020-030469, the contents of which are incorporated herein by reference. Background Patent document 1 discloses a gas bearing device including an annular top foil having a rotatable cylindrical rotation shaft passing through the inside and having an inner peripheral surface spaced from an outer peripheral surface of the rotation shaft, a damping member provided on the outer periphery of the top foil and damping vibrations in a direction intersecting with an axial core of the rotation shaft, and an annular housing provided on the outer periphery of the damping member. Prior art literature Patent literature Patent document 1 Japanese patent application laid-open No. 2020-122555 Summary of the inventionproblems to be solved by the invention However, in the gas bearing device disclosed in patent document 1, if the damping member (return spring) has a high rigidity, a gas film cannot be formed between the rotary shaft and the top foil when the rotary shaft rotates at a high speed, and mechanical loss may increase. On the other hand, if the stiffness of the damping member (return spring) is small, the rotary shaft cannot be rotatably supported at the time of low-speed rotation of the rotary shaft. The present disclosure has been made in view of the above-described problems, and an object thereof is to provide a gas bearing device and a turbocharger that can reliably form a gas film between a rotating shaft and a top foil when the rotating shaft rotates at a high speed and can reliably support the rotating shaft to be rotatable when the rotating shaft rotates at a low speed. Technical scheme for solving problems In order to achieve the above object, the present disclosure provides a gas bearing device, The rotary shaft is rotatably supported by a gas serving as a working fluid, and the rotary shaft comprises: A housing through which the rotation shaft passes; an annular top foil provided inside the housing and surrounding an outer periphery of the rotation shaft; A return spring provided between the top foil and the housing, the return spring having a plurality of hills in contact with the top foil and valleys in contact with the housing; A pair of snap rings fitted into shaft holes penetrating the rotary shaft of the housing, the movement of the return spring being restricted in the axial direction of the rotary shaft, The inner peripheral surfaces of the pair of snap rings each have self-lubricity. Effects of the invention According to the gas bearing device of the present disclosure, since the inner peripheral surfaces of the pair of snap rings each have self-lubricity, it is not necessary to support the load of the rotating shaft only by the return spring at the time of low-speed rotation of the rotating shaft, and the support rigidity of the return spring can be reduced. Thus, a gas film can be reliably formed between the rotary shaft and the top foil when the rotary shaft rotates at a high speed. In addition, by reducing the supporting rigidity of the return spring, the pair of snap rings supports the rotary shaft at the time of low-speed rotation of the rotary shaft, but the pair of snap rings can reliably support the rotary shaft rotatably by the self-lubricity of the inner peripheral surfaces of the rotary shafts of the pair of snap rings. Drawings Fig. 1 is a longitudinal sectional view schematically showing the structure of a turbocharger incorporating a gas bearing device according to an embodiment. Fig. 2 is a longitudinal sectional view schematically showing the structure of the gas bearing device shown in fig. 1. Fig. 3 is a transverse cross-sectional view schematically showing the structure of the gas bearing device shown in fig. 2. Fig. 4-1 is a front view of the snap ring shown in fig. 2. Fig. 4-2 is a transverse cross-sectional view (A-A cross-sectional view) of the snap ring shown in fig. 4-1. Fig. 5-1 is a diagram (cross-sectional view) schematically showing a relationship between a retainer ring and a return spring, and shows a state before a rotation shaft is provided. Fig. 5-2 is a diagram (cross-sectional view) schematically showing a relationship between the retainer ring and the return spring, and shows a state of the rotary shaft at a low speed rotation. Fig. 5 to 3 are diagrams (cross-sectional views) schematically showing the relationship between the retainer ring and the return spring, and are diagrams showing the state of the rotary shaft at the time of medium-speed rotation. Fig. 6 is a view for explaining the supporting rigidity of the return spring. Fig. 7-1 is a schematic view schematically showing an example in which the return spring provided between the top foil and the case is made of a bimetal, and shows a state at a low temperature. Fig.