JP2020122555A - Gas bearing and rotating machine - Google Patents

Abstract

To ensure that vibration of a rotating shaft can be reduced.SOLUTION: A gas bearing 1 comprises: ring-shaped top foil 2 inside which a rotatable cylindrical rotating shaft 13 is passed, and of which an inner peripheral surface 2B is located at a distance from an outer peripheral surface 13B of the rotating shaft 13; a damping member 3 provided on an outer periphery of the top foil 2, and for damping vibration in a direction intersecting with an axis 13A of the rotating shaft 13 during rotation by being in contact with the top foil 2; and a ring-shaped housing 4 provided on an outer periphery of the damping member 3. In the damping member 3, a plurality of meshes 6 made of metal are laminated. The plurality of meshes 6 constituting the damping member 3 have a same shape.SELECTED DRAWING: Figure 2

Description

The present invention relates to a gas bearing and a rotary machine including the gas bearing.

Exhaust turbine superchargers, air compressors, etc., which are rotating machines, may include gas bearings (see, for example, Patent Document 1 and Patent Document 2).

JP, 2018-28387, A U.S. Patent Application Publication No. 2007/0047858A1

The gas bearings shown in Patent Document 1 and Patent Document 2 use gas as a lubricant, and therefore have less friction loss and are suitable for high speed rotation. However, the gas bearing has a problem of low damping property, and it is required to improve load capacity that is the ability to damp the vibration of the rotating shaft, and it is required to reduce the vibration of the rotating shaft.

The present invention solves the above-mentioned problems, and an object of the present invention is to provide a gas bearing and a rotating machine that can reduce vibration of a rotating shaft.

In order to achieve the above-mentioned object, the gas bearing of the present invention includes a ring-shaped top foil in which a rotatable cylindrical rotating shaft is passed inside and an inner peripheral surface of which is spaced from an outer peripheral surface of the rotating shaft. A damping member that is provided on the outer circumference of the top foil and that damps vibrations in a direction intersecting the axis of the rotating shaft that is rotating; and a ring-shaped housing that is provided on the outer circumference of the damping member. In the gas bearing, the damping member is characterized in that a plurality of meshes made of metal are laminated.

This gas bearing is formed by laminating a plurality of meshes made of metal, which are provided on the outer circumference of the top foil and which dampen vibrations in a direction intersecting the axis of the rotary shaft. Therefore, in the gas bearing, the meshes slide with each other due to the vibration in the direction intersecting the axis of the rotary shaft, the vibration energy of the rotary shaft can be absorbed, and the vibration of the rotary shaft can be reduced. As a result, the gas bearing can improve the load capacity, which is the capacity to damp the vibration of the rotating shaft.

The gas bearing of the present invention is characterized in that the plurality of meshes forming the damping member have the same shape.

In this gas bearing, since the plurality of meshes forming the damping member have the same shape, the meshes can slide reliably due to vibration in the direction intersecting the axis of the rotary shaft.

The gas bearing of the present invention is characterized in that the mesh includes an intersecting portion which is an intersecting portion of the lattice and a plurality of protruding portions protruding from the intersecting portion.

This gas bearing has mesh-shaped mesh portions and a plurality of protrusions protruding in the thickness direction from the mesh portions. Therefore, when the meshes slide, the mesh portions and the protrusions Will also slide.

The gas bearing according to the present invention is characterized in that the damping member has a plurality of inner circumferential curved portions that are convexly curved toward the top foil and have a top portion in contact with the top foil in the circumferential direction.

In this gas bearing, since the damping member has a plurality of inner curved portions that are convexly curved toward the top foil and are arranged in the circumferential direction, the contact area between the meshes can be increased and the load capacity can be improved. You can

In the gas bearing of the present invention, the damping member is divided into a plurality of divided damping members, and the interval between the apex portions of the divided damping members adjacent to each other gradually increases toward the downstream side in the rotation direction of the rotating shaft. It is characterized by being narrow.

In this gas bearing, the damping member includes a plurality of divided damping members, and the spacing between the tops of the divided damping members becomes gradually narrower toward the downstream side in the rotation direction of the rotating shaft. It is possible to gradually improve the distance from the upstream side to the downstream side of the top foil so that the downstream side in the rotation direction of the rotating shaft of the split damping member of the top foil can be regulated from moving further away from the outer peripheral surface of the rotating shaft than the upstream side. Is deformed into a wedge shape in which the distance from the outer peripheral surface of the rotary shaft gradually becomes smaller from the upstream side to the downstream side in the rotation direction of the split damping member. As a result, in the gas bearing, the air between the top foil and the rotary shaft can be made difficult to escape from the downstream side in the rotation direction of the split damping member, and the pressure of the air between the top foil and the rotary shaft is improved. be able to.

A rotary machine of the present invention is characterized by including the gas bearing, a machine body attached to an outer peripheral surface of the housing, and the rotary shaft.

Since this rotary machine is provided with the above-mentioned gas bearing, the load capacity of the gas bearing can be improved, so that the vibration of the rotating shaft can be reduced.

According to the present invention, vibration of the rotating shaft can be reduced.

FIG. 1 is a schematic diagram of an exhaust turbine supercharger according to the first embodiment. FIG. 2 is a side view schematically showing the gas bearing taken along the line II-II in FIG. FIG. 3 is a perspective view showing a mesh that constitutes the damping member of the gas bearing shown in FIG. FIG. 4 is a side view of the mesh shown in FIG. FIG. 5 is a side view showing a state in which a plurality of meshes shown in FIG. 4 are stacked. FIG. 6 is a side view of a part of the state in which the meshes are stacked between the metal molds shown in FIG.

Embodiments according to the present invention will be described below in detail with reference to the drawings. The present invention is not limited to this embodiment. In addition, constituent elements in the following embodiments include elements that can be easily replaced by those skilled in the art, or substantially the same elements.

[Embodiment 1]
FIG. 1 is a schematic diagram of an exhaust turbine supercharger according to the first embodiment. FIG. 2 is a side view schematically showing the gas bearing taken along the line II-II in FIG. FIG. 3 is a perspective view showing a mesh that constitutes the damping member of the gas bearing shown in FIG. FIG. 4 is a side view of the mesh shown in FIG. FIG. 5 is a side view showing a state in which a plurality of meshes shown in FIG. 4 are stacked. FIG. 6 is a side view of a part of the state in which the meshes are stacked between the metal molds shown in FIG.

An exhaust turbine supercharger 10 that is a rotary machine according to the first embodiment uses a flow of exhaust gas of an internal combustion engine (not shown) to drive a compressor 11 to increase the density of air taken in by the internal combustion engine. Is. As shown in FIG. 1, the exhaust turbine supercharger 10 is mainly composed of a turbine 12, a compressor 11, a rotary shaft 13, and a gas bearing 1, and these are housed in a housing 14 which is a machine body. ing.

The housing 14 has a hollow interior, and includes a turbine housing 14A that houses the turbine 12, a compressor housing 14B that houses the compressor 11, and a bearing housing 14C that houses the rotating shaft 13. The bearing housing 14C is located between the turbine housing 14A and the compressor housing 14B.

The rotating shaft 13 is formed in a cylindrical shape and is rotatably supported by the gas bearing 1. In the first embodiment, the rotating shaft 13 is rotated around the axis 13A along an arrow (hereinafter, referred to as a rotating direction) DR. The turbine disk 12A of the turbine 12 is fixed to one end of the rotary shaft 13 in the axial direction. The turbine disk 24 is housed in the turbine housing 14A, and a plurality of axial-flow turbine blades 12B are provided on the outer peripheral portion at predetermined intervals in the circumferential direction. Further, the rotary shaft 13 has a compressor impeller 11A of the compressor 11 fixed to the other end in the axial direction. The compressor impeller 11A is housed in a compressor housing 14B, and a plurality of blades 11B are provided on the outer peripheral portion at predetermined intervals in the circumferential direction.

The turbine housing 14A is provided with an exhaust gas inlet passage 141A and an exhaust gas outlet passage 142A for the internal combustion engine. The turbine housing 14A is provided with a turbine nozzle 143A between the inlet passage 141A and the turbine blade 12B. The turbine nozzle 143A guides the exhaust gas flow in the axial direction statically expanded by the turbine nozzle 143A to the plurality of turbine blades 12B. The turbine 12 can be rotationally driven. The compressor housing 14B is provided with an intake port 141B and a compressed air discharge port 142B. The compressor housing 14B is provided with a diffuser 143C between the compressor impeller 11A and the compressed air discharge port 142B. The air compressed by the compressor impeller 11A is discharged toward the internal combustion engine through the diffuser 143C.

Therefore, in the exhaust turbine supercharger 10, the turbine 12 is driven to rotate about the axis by the exhaust gas discharged from the internal combustion engine, the rotation of the turbine 12 is transmitted to the rotating shaft 13, and the compressor 11 rotates about the axis. Driven. The exhaust turbine supercharger 10 compresses the air taken in by the compressor 11 through the intake port 141B and supplies the compressed air to the internal combustion engine. Therefore, the exhaust gas of the internal combustion engine passes through the exhaust gas inlet passage 141A, is subjected to static pressure expansion by the turbine nozzle 143A, and the axial exhaust gas flow is guided to the plurality of turbine blades 12B. The turbine 12 is rotationally driven via the turbine disk 12A to which is fixed. The exhaust gas that has driven the plurality of turbine blades 12B is exhausted to the outside from the outlet passage 142A. On the other hand, when the rotating shaft 13 is rotated by the turbine 12, the integrated compressor impeller 11A is rotated and air is sucked through the suction port 141B. The sucked air is compressed by the compressor impeller 11A to become compressed air, and this compressed air passes through the diffuser 143B and is supplied from the compressed air discharge port 142B to the internal combustion engine.

The gas bearing 1 supports the rotating shaft 13 rotatably around the shaft center with respect to the housing 14, and attenuates vibration in a direction intersecting with the shaft center 13A of the rotating shaft 13. The gas bearing 1 is a so-called air bearing that uses air as a working fluid. As shown in FIG. 2, the gas bearing 1 includes a top foil 2, a damping member 3, and a housing 4.

The top foil 2 is formed in a ring shape, the rotating shaft 13 is passed inside, and the inner peripheral surface 2</b>B is arranged so as to be spaced apart from the outer peripheral surface 13</b>B of the rotating shaft 13. The top foil 2 integrally includes a ring-shaped ring portion 21 and a protruding piece 22 that protrudes from the ring portion 21 in the outer peripheral direction. In the first embodiment, the ring portion 21 has a notch 23 in a part thereof. The protruding piece 22 protrudes from the end of the notch 23 in the outer peripheral direction of the ring portion 21. The top foil 2 is formed by pressing a metal plate. Further, in the first embodiment, the top foil 2 is coated with a lubricating film (not shown). The lubricating film is made of, for example, PTFE mixed with molybdenum disulfide (MoS ₂ ), polytetrafluoroethylene (PTFE), or polyamide-imide (PAI).

The damping member 3 is formed in a ring shape and is provided on the outer circumference of the top foil 2. The damping member 3 comes into contact with the top foil 2 to damp vibrations in the intersecting direction at the axis 13A of the rotary shaft 13. The structure of the damping member 3 will be described later.

The housing 4 is formed in a ring shape and is provided on the outer circumference of the damping member 3. The outer peripheral surface 4A of the housing 4 is fixed to the bearing housing 14C. The top foil 2, the damping member 3 and the housing 4 of the gas bearing 1 described above are arranged coaxially.

The damping member 3 is divided into a plurality of divided damping members 5, as shown in FIG. The plurality of divided damping members 5 are arranged at intervals in the circumferential direction and are housed between the top foil 2 and the housing 4. In the first embodiment, the damping member 3 is composed of three divided damping members 5. The divided damping members 5 are equal to each other within an error range of about ±1 degree in an angle θ about the axis 2A of the top foil 2. The angle θ about the axis 2A of the top foil 2 is an angle formed by the line segments 51A and 52A connecting the two ends 51 and 52 in the circumferential direction of the split damping member 5 and the axis 2A. Further, in the first embodiment, the divided damping members 5 are equal to each other within an error range of about ±1 degree with respect to the angle θ about the axis 2A of the top foil 2, but in the present invention, the angles θ are different from each other. May be.

The split damping member 5 has a plurality of inner curved portions 53 that are convexly curved toward the top foil 2 and are arranged in the circumferential direction. Both ends of the plurality of inner peripheral curved portions 53 in the circumferential direction are continuous with each other. Further, a top portion 53</b>A of the inner circumferential curved portion 53 near the top foil 2 contacts the top foil 2. As described above, in the present invention, the top portion 53A of the inner peripheral curved portion 53 is a portion located closer to the top foil 2 than other portions of the inner peripheral curved portion 53 and contacting the top foil 2. The interval d between the tops 53A of the inner peripheral curved portions 53 adjacent to each other in the circumferential direction of each divided damping member 5 is formed to be gradually narrowed toward the downstream D in the rotation direction DR of the rotary shaft 13.

Each divided damping member 5 is formed by stacking a plurality of meshes 6 made of metal and shown in FIG. In the first embodiment, each divided damping member 5 has three meshes 6 laminated. As shown in FIG. 3, the mesh 6 includes a grid-shaped mesh portion 60 and a plurality of protrusions 61 that protrude from the mesh portion 60 in the thickness direction of the mesh 6. The thickness direction is a direction in which the plurality of meshes 6 are stacked on each other. The net portion 60 integrally includes a plurality of first linear members 62 and a plurality of second linear members 63. In the first embodiment, the first linear member 62 and the second linear member 63 extend linearly and are orthogonal to each other before the inner peripheral curved portion 53 is formed in each divided damping member 5.

The protruding portion 61 is formed in a needle shape protruding in the thickness direction from the net portion 60 before the inner peripheral curved portion 53 is formed on each divided damping member 5. In the first embodiment, a plurality of protrusions 61 are provided on each of one side and the other side in the thickness direction from the intersection 64 which is the intersection of the first linear member 62 and the second linear member 63 (in the first embodiment, 3) It is protruding. In the first embodiment, the three projecting portions 61 projecting from the respective intersecting portions 64 are gradually separated from each other as they are separated from the mesh portion 60 before the inner peripheral curved portion 53 is formed in each divided damping member 5. The spacing is increasing.

In the first embodiment, the mesh 6 is manufactured by a 3D printer. In the first embodiment, the three meshes 6 have the same shape. Further, in the first embodiment, since the three meshes 6 are manufactured by the 3D printer, the dimensional error of each part is smaller than that in the case of being manufactured by another manufacturing method such as press working.

As shown in FIG. 5, the split damping member 5 has three meshes 6 laminated so that the intersecting portions 64 and the tips of the projecting portions 61 overlap each other. The plurality of meshes 6 that are laminated in this way and that constitute the divided damping member 5 of the damping member 3 are multiplexed. As shown in FIG. 6, the divided damping member 5 is arranged between the upper mold 101 and the lower mold 102 of the mold 100 in a state where the three meshes 6 are overlapped, and the upper mold 101 and the lower mold 100 are arranged. By making 102 and 102 close to each other, an inner peripheral curved portion 53 is formed and curved along the outer peripheral surface of the top foil 2. The upper mold 101 and the lower mold 102 are formed with molding surfaces 101A and 102A along the inner peripheral curved portion 53 on the surfaces facing each other. 6 omits that the molding surfaces 101A and 102A of the upper mold 101 and the lower mold 102 are curved along the outer peripheral surface 2C of the top foil 2, but in reality, the upper mold 101 is The molding surfaces 101A and 102A of the lower die 102 are formed along the inner peripheral curved portion 53 while being curved along the outer peripheral surface 2C of the top foil 2.

In the gas bearing 1 described above, when the rotating shaft 13 rotates about the shaft center 13A in the rotating direction DR indicated by the arrow in the drawing, a gap between the inner peripheral surface 2B of the top foil 2 and the outer peripheral surface 13B of the rotating shaft 13 is formed. The pressure of air is increased. Specifically, the top foil 2 is pushed toward the downstream D side in the rotation direction DR due to the friction with the air flowing as the rotating shaft 13 rotates, and the inner peripheral surface 2B from the outer peripheral surface 13B of the rotating shaft 13. The top foil 2 tries to deform in the direction away from it. Since the distance d between the adjacent tops 53A of the respective divided damping members 5 of the damping member 3 becomes gradually narrower toward the downstream D side in the rotational direction DR, the rigidity of each divided damping member 5 becomes downstream D in the rotational direction DR. It is getting higher gradually toward the side. For this reason, in the gas bearing 1, the distance between the inner peripheral surface 2B and the outer peripheral surface 13B of the rotary shaft 13 gradually increases toward the upstream U side in the rotational direction DR of each divided damping member 5. The top foil 2 will be deformed.

Therefore, the gas bearing 1 is gradually provided between the inner peripheral surface 2B of the ring portion 21 of the top foil 2 and the outer peripheral surface 13B of the rotary shaft 13 toward the downstream D side in the rotation direction DR of each divided damping member 5. A narrowed gap is formed and air is pushed into the gap. As a result, in the gas bearing 1, the pressure of air in the gap between the inner peripheral surface 2B of the ring portion 21 of the top foil 2 and the outer peripheral surface 13B of the rotary shaft 13 is increased, and the rotary shaft 13 is supported by the pressure of this air. Support in the radial direction without contact.

At this time, in the gas bearing 1, due to the flexibility of the divided damping members 5 of the top foil 2 and the damping member 3, the inner peripheral surface 2B of the top foil 2 has a load, a rotation speed of the rotating shaft 13, an ambient temperature, etc. The width of the above-mentioned gap is automatically adjusted to an appropriate width according to the operating conditions, because it is arbitrarily deformed according to the operating conditions. Therefore, the gas bearing 1 can adjust the width of the above-described gap to an optimum width even under severe conditions such as high temperature and high speed rotation, and can stably support the rotating shaft 13. Further, in the gas bearing 1, when the rotary shaft 13 vibrates in the direction intersecting the axis 13A during the rotation of the rotary shaft 13, the influence of air in which the pressure in the gap is increased and the configuration of each split damping member 5 are increased. The meshes 6 to be slid on each other slide, and the vibration energy of the rotating shaft 13 can be attenuated by the friction energy generated by the sliding.

As described above, in the gas bearing 1 according to the first embodiment, the mesh in which the damping member 3 which is provided on the outer periphery of the top foil 2 and damps the vibration in the direction intersecting with the axis 13A of the rotating shaft 13 is made of metal is used. A plurality of 6 are laminated. Therefore, in the gas bearing 1, the meshes 6 slide with each other due to the vibration in the direction intersecting with the axis 13A of the rotating shaft 13 to generate friction energy due to the sliding, and the meshes 6 slide with each other. The vibration energy of the rotary shaft 13 can be absorbed by the movement, and the vibration of the rotary shaft 13 can be reduced. As a result, the gas bearing 1 can improve the load capacity, which is the capacity to damp the vibration of the rotating shaft 13.

Further, in the gas bearing 1 according to the first embodiment, since the plurality of meshes 6 forming the split damping member 5 have the same shape, the meshes 6 are surely caused by the vibration in the direction intersecting with the axis 13A of the rotating shaft 13. It will slide.

In addition, in the gas bearing 1 according to the first embodiment, the mesh 6 includes the mesh portion 60 having a lattice shape and the plurality of protruding portions 61 protruding in the thickness direction from the mesh portion 60, so that the meshes 6 slide with each other. When this happens, not only the nets 60 but also the protrusions 61 slide. As a result, the gas bearing 1 can absorb the vibration energy of the rotating shaft 13 due to the sliding of the meshes 6 and reduce the vibration of the rotating shaft 13.

Further, in the gas bearing 1 according to the first embodiment, since the divided damping member 5 has a plurality of inner circumferential curved portions 53 that are convexly curved toward the top foil 2, they are arranged in the circumferential direction. It can be increased, vibration of the rotary shaft 13 can be reduced, and load capacity can be improved.

Further, in the gas bearing 1 according to the first embodiment, the damping member 3 includes a plurality of divided damping members 5, and the interval d between the adjacent top portions 53A of the divided damping member 5 is the downstream D in the rotation direction DR of the rotating shaft 13. The rigidity of each divided damping member 5 is gradually improved from the upstream U side in the rotation direction DR toward the downstream D side, and the rotation axis 13 of the divided damping member 5 of the top foil 2 is gradually decreased. It is possible to restrict the downstream D side of the rotation direction DR of the above from the outer peripheral surface 13B of the rotating shaft 13 more than the upstream U side, and direct the top foil 2 from the upstream U side of the split damping member 5 in the rotation direction DR to the downstream D side. Thus, the rotary shaft 13 is deformed into a wedge shape in which the distance from the outer peripheral surface 13B is narrowed. As a result, in the gas bearing 1, the air between the inner peripheral surface 2B of the top foil 2 and the outer peripheral surface 13B of the rotary shaft 13 can be prevented from escaping from the downstream D side of the split damping member 5 in the rotation direction DR, The pressure of air in the gap between the inner peripheral surface 2B of the top foil 2 and the outer peripheral surface 13B of the rotary shaft 13 can be improved.

Further, in the gas bearing 1 according to the first embodiment, since the meshes 6 constituting the damping member 3 are laminated so that the intersecting portions 64 and the tips of the protruding portions 61 overlap each other, when the meshes 6 slide with each other. In addition, the protrusions 61 slide on each other.

Further, the exhaust turbine supercharger 10 of the present invention includes the gas bearing 1 described above and can improve the load capacity of the gas bearing 1, so that the vibration of the rotating shaft 13 can be reduced.

In the first embodiment described above, the exhaust turbine supercharger 10 which is a rotary machine is shown. However, in the present invention, the rotary machine including the gas bearing 1 is not limited to the exhaust turbine supercharger 10 and may be, for example, an air compressor of an air conditioner used for air conditioning in the cabin of an aircraft. Further, in the first embodiment, the plurality of laminated meshes 6 forming the damping member 3 are curved so as to have the plurality of inner peripheral curved portions 53, but the present invention is not limited to this, and the damping member is not limited thereto. It is not necessary to form the inner peripheral curved portion 53 on the mesh 6 which is composed of three parts. Further, in the first embodiment, each divided damping member 5 has three meshes 6 laminated, but the present invention is not limited to three meshes, and at least two meshes 6 may be laminated. Good. Further, in the first embodiment, the damping member 3 includes three divided damping members 5, but the present invention is not limited to three and may include at least two divided damping members 5. ..

1 gas bearing 2 top foil 2B inner peripheral surface 3 damping member 4 housing 5 split damping member 6 mesh 10 exhaust turbine supercharger (rotating machine)
13 rotary shaft 13A shaft center 13B outer peripheral surface 14 housing (machine body)
53 inner curved part 53A top part 60 net part 61 protrusion part DR rotation direction d interval θ angle

Claims (6)

A ring-shaped top foil, through which a rotatable cylindrical rotation shaft is passed inside, and an inner peripheral surface of which is spaced from the outer peripheral surface of the rotation shaft,
A damping member that is provided on the outer periphery of the top foil and that damps vibrations in a direction intersecting the axis of the rotating shaft during rotation,
A gas bearing provided with a ring-shaped housing provided on the outer periphery of the damping member,
The said damping member is a gas bearing characterized by laminating|stacking several meshes comprised by metal. The gas bearing according to claim 1, wherein the plurality of meshes forming the damping member have the same shape. The gas bearing according to claim 2, wherein the mesh includes an intersecting portion that is an intersecting portion of a lattice and a plurality of protruding portions that protrude from the intersecting portion. 4. The damping member has a plurality of inner circumferential curved portions, which are convexly curved toward the top foil and have a top portion contacting the top foil, arranged in the circumferential direction. Gas bearing described in. The damping member is divided into a plurality of split damping members,
The gas bearing according to claim 4, wherein a distance between the tops of the split damping members adjacent to each other is gradually narrowed toward the downstream side in the rotation direction of the rotation shaft. A gas bearing according to any one of claims 1 to 5,
A machine body attached to the outer peripheral surface of the housing,
A rotating machine comprising the rotating shaft.

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