Tilting pad journal bearing manufacturing method, tilting pad journal bearing, and compressor

Abstract

A tilting pad journal bearing manufacturing method includes a first process and a second process. In the first process, a pivot fitting hole is formed on a convex curved outer circumferential surface of the tilting pad. The pivot fitting hole is recessed from the outer circumferential surface toward an inner circumferential surface and has an inner diameter smaller than an outer diameter of the distal end portion of the pivot. In the second process, a concave portion is formed on the concave curved inner circumferential surface of the tilting pad by attaching the distal end portion of the pivot to the pivot fitting hole by interference-fitting.

Claims

1. A method for manufacturing a tilting pad journal bearing including a bearing housing formed in a tubular shape and having a rotary shaft inserted therein, a substantially columnar pivot integrally attached to the bearing housing, and a tilting pad attached to a distal end portion of the substantially columnar pivot and disposed to surround the rotary shaft inside the bearing housing, the method comprising: machining a metal material into a back metal portion of the tilting pad that includes an inner circumferential surface with a concave circular arc surface having a predetermined curvature; affixing a resin material by laminating to the inner circumferential surface of the back metal portion of the tilting pad, wherein laminating the resin material uses a metal mold that pressure-welds and integrates the resin material with the inner circumferential surface portion of the tilting pad; machining the back metal portion of the tilting pad to form an outer circumferential surface with a convex circular arc that has a predetermined curvature, and forming a pivot fitting hole at a predetermined position on the outer circumferential surface, wherein when forming the pivot fitting hole, an inner diameter of the pivot fitting hole is made smaller than an outer diameter of the distal end portion of the substantially columnar pivot; and forming a concave portion on a concave curved inner circumferential surface of the tilting pad by attaching the distal end portion of the substantially columnar pivot to the pivot fitting hole by interference-fitting.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a perspective view showing a pivot and a tilting pad of a tilting pad journal bearing according to an embodiment of the present invention.

(2) FIG. 2A is a view showing a 2D shape measurement result (an axial direction of a pivot position) of an inner circumferential surface (a concave portion) of the tilting pad.

(3) FIG. 2B is a cross-sectional view showing an example of an inner circumferential surface (a concave portion) of the tilting pad of the tilting pad journal bearing according to an embodiment of the present invention.

(4) FIG. 3A is a perspective view showing a pivot of the tilting pad journal bearing according to an embodiment of the present invention.

(5) FIG. 3B is a perspective view showing the pivot of the tilting pad journal bearing according to an embodiment of the present invention.

(6) FIG. 4 is a flowchart showing an example of a liking pad journal bearing manufacturing method according to an embodiment of the present invention.

(7) FIG. 5 is a view showing a process of pressure-welding a resin material against the inner circumferential surface of the tilting pad in the tilting pad journal bearing manufacturing method according to an embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

(8) Hereinafter, a tilting pad journal bearing manufacturing method, a tilting pad journal beating, and a compressor according to an embodiment of the present invention will be described referring to FIGS. 1 to 5.

(9) In this embodiment, description will be provided on the assumption that the tilting pad journal bearing according to the present invention is a dynamic pressure gas bearing. The dynamic pressure gas bearing compresses a gas between the inner circumferential surfaces of each tilting pad (bearing pad) and the outer circumferential surface of the rotary shaft and generates a dynamic pressure, using gas rather than oil or water as a lubricant. That is, the dynamic pressure gas bearing rotatably supports a rotary shaft that rotates at a high speed, by forming a gas film (a lubricating film) between the inner circumferential surfaces of each tilting pad and the outer circumferential surface of the rotary shaft.

(10) The compressor of this embodiment is, for example, a turbo compressor or the like, and is configured to rotate the rotary shaft at high speed around the axis and compress the fluid by utilizing the rotation of the rotary shaft. For example, an impeller is rotated by the rotary shaft, and the gas is compressed by the centrifugal force of the rotating impeller.

(11) The compressor includes a tilting pad journal bearing as means for rotatably supporting the rotary shaft.

(12) As shown in FIG. 1, a tilting pad journal bearing A of the present embodiment includes a bearing housing (not shown), a plurality of pivots 1, and a plurality of tilting pads 2. The bearing housing (not shown) is formed in a substantially cylindrical shape. A rotary shaft (not shown) is inserted into the bearing housing (not shown). The axes of the bearing housing (not shown) and the rotary shaft (not shown) are disposed coaxially with each other.

(13) The plurality of pivots 1 are integrally attached to the bearing housing (not shown).

(14) Each of the plurality of tilting pads 2 is formed in a circular arc-shaped plate shape when viewed from an axial direction. The tilting pads 2 are attached to a distal end portions 1a of the pivot 1, respectively. The tilting pads 2 are arranged in a substantially ring shape to surround the rotary shaft (not shown) in the bearing housing (not shown).

(15) The tilting pad 2 of this embodiment is provided with a pivot fitting hole 3. The pivot fitting hole 3 is recessed from the outer circumferential surface 2a of the tilting pad 2 toward the inner circumferential surface 2b side. The pivot fitting hole 3 is formed to have a diameter smaller than an outer diameter of the distal end portion 1a of the pivot 1 which is formed in a substantially columnar shape. The distal end portion 1a of the pivot 1 is attached to each pivot fitting hole 3 of each tilting pad 2 by interference fitting such as a shrinkage-fitting, a cold-fitting, and a press-fitting. That is, the tilting pad 2 is integrally fixed to the pivot 1 and is supported by the pivot 1.

(16) As shown in FIG. 2B, each tilting pad 2 has a concave portion 4 formed on a concave curved inner circumferential surface 2b. The concave portion 4 has a substantially concave curved surface 4a with an extension line of an axis O1 of the pivot 1 as a substantial center.

(17) As shown in FIGS. 3A and 3B, the pivot 1 of this embodiment is formed in a substantially columnar shape, and has a compressed gas supply path 5 formed to penetrate from a rear end portion 1b side to the distal end portion 1a (distal end surface). The compressed gas supply path 5 is intended to supply the compressed gas between the inner circumferential surfaces 2b of each tilting pad 2 and the outer circumferential surface (not shown) of the rotary shaft before starting to rotate the rotary shaft. By forming a gas film between the inner circumferential surface 2b of the tilting pad 2 and the outer circumferential surface (not shown) of the rotary shaft, it is possible to bring the tilting pad 2 and the rotary shaft into a non-contact state.

(18) Next, a method for manufacturing the tilting pad journal bearing A in the present embodiment will be described with reference to FIG. 4. In order to manufacture the tilting pad journal bearing A of the present embodiment having the above-described configuration, metal material is first machined to roughly process a back metal portion 2c (see FIG. 5) of the tilting pad 2 (step S01).

(19) Next, a resin material 6 such as poly ether ether ketone resin (PEEK) is affixed by laminating to an inner circumferential surface 2d (see FIG. 5) of the back metal portion 2c of the tilting pad 2 formed into a concave circular arc surface shape having a predetermined curvature by rough processing. Further, the resin material 6 is pressure-welded by the metal mold 7, and the resin material 6 is integrated with the inner circumferential surface portion of the tilting pad 2 (step S02).

(20) Next, the back metal portion 2c of the tilting pad 2 is machined to form a convex circular arc-shaped outer circumferential surface 2a having a predetermined curvature as shown in FIG. 1. Further, a pivot fitting hole 3 is formed at a predetermined position on the outer circumferential surface 2a (a first process). When forming the pivot fitting hole 3, its inner diameter is made slightly smaller than the outer diameter of the distal end portion 1a of the substantially columnar pivot 1. For example, in the present embodiment, the pivot fitting hole 3 is formed to have a diameter smaller than the outer diameter of the pivot 1 by about 100 m. Further, as described above, the tilting pad 2 (the back metal portion 2c) formed into a circular arc shape having a predetermined shape is finished (step S03).

(21) Next, the distal end portion 1a of the substantially columnar pivot 1 is attached to the pivot fitting hole 3 of the tilting pad 2 by interference-fitting such as shrink-fitting, cold-fitting, or press-fitting (a second process). As a result, the pivot 1 is set to a state of being integrally attached to the tilting pad 2.

(22) At this time, by attaching the distal end portion 1a of the pivot 1 to the pivot fitting hole 3 with interference-fitting, as shown in FIGS. 2A and 2B, an interference-fitting is performed, and at the same time, a concave portion 4 is automatically formed on the concave curved inner circumferential surface 2b of the tilting pad 2. When the interference-fitting is performed, a force drawn toward the outer circumferential surface 2a, that is, the inner side inevitably occurs with respect to the concave curved inner circumferential surface 2b of the tilting pad 2. The concave portion 4 is automatically formed on the inner circumferential surface 2b by this force.

(23) For example, when the pivot 1 having an outer diameter of the distal end portion 1a of 50 mm is interference-fitted into the pivot fitting hole 3 having a smaller diameter than the outer diameter of the distal end portion 1a of the pivot 1 by about 100 m, the concave portion 4 having a concave curved surface 4a having a maximum depth h of about 15 m and an inner diameter t of about 100 mm is automatically formed with the extension line of the axis O1 of the pivot 1 substantially at the center.

(24) According to the tilting pad journal bearing A of the present embodiment, since the concave portion 4 is formed on the concave curved inner circumferential surface 2b of the tilting pad 2, it is possible to induce the flow of the gas as the lubricant toward the concave portion 4, and the flow of the lubricant around the concave portion 4. Therefore, it is possible to suppress the local temperature rise of the central portion of the tilting pad 2 and the local pressure rise of the lubricating film.

(25) This makes it possible to suppress occurrence of the local deformation in the tilting pad 2. As a result, it is possible to improve bearing performance (load capacity).

(26) An embodiment of the method for manufacturing the tilting pad journal bearing, the tilting pad journal bearing, and the compressor according to the present invention have been described above. However, the present invention is not limited to the above-described embodiment and can be appropriately changed within the scope that does not depart from the spirit of the invention.

(27) For example, in the present embodiment, the tilting pad journal bearing A according to the present invention is provided in a compressor such as a turbo compressor. However, the tilting pad journal bearing A according to the present invention can be applied to any bearing for suitably supporting a radial load and rotatably supporting a rotary shaft that rotates around an axis.

(28) The compressor of the present invention is provided with the tilting pad journal bearing A, may be configured to compress the fluid in accordance with the rotation of the rotary shaft around the axis, and may be, for example, a compressor other than a turbo compressor, such as a rotary compressor and a scroll compressor.

(29) In the present embodiment, the tilting pad journal bearing A according to the present invention has been described as a dynamic pressure gas bearing that uses gas, rather than oil or water, as a lubricant. However, the tilting pad journal bearing A according to the present invention may rotatably support the rotary shaft, using a lubricant such as oil or water other than a gas. In this case, it is also possible to obtain the same operation and effects as the present embodiment.

INDUSTRIAL APPLICABILITY

(30) The present invention can be applied to a tilting pad journal bearing and a compressor. According to the present invention, since it is possible to suppress occurrence of local deformation in the tilting pad, the bearing performance (load capability) can be improved.

REFERENCE SIGNS LIST

(31) 1 Pivot 1a Distal end portion 1b Rear end portion 2 Tilting pad (bearing pad) 2a Outer circumferential surface 2b inner circumferential surface 2c Back metal portion 2d Inner circumferential surface of back metal portion. 3 Pivot fitting hole 4 Concave portion 4a Concave curved surface 5 Compressed gas supply path 6 Resin material 7 Metal old O1 Axis of pivot