Compressor and assembly method for same

Abstract

Provided is a compressor that can facilitate centering of a compression unit with respect to a housing. This compressor comprises: a housing (11); a rotary compression unit accommodated in the housing (11); a rotating shaft (15) for driving the rotary compression unit; plug welding parts (35) for fixing the rotary compression unit to the housing (11) by welding; and shims (37) respectively inserted between the outer peripheral surfaces of arm parts (32b) of a lower bearing (32), which is the rotary compression unit, and the inner peripheral surface of the housing (11). The plurality of the arm parts (32b) each extend in the radial direction, the plug welding parts (35) are respectively provided on the outer peripheral surfaces of the arm parts (32b), and the shims (37) are respectively disposed in the peripheries of the plug welding parts (35).

Description

Technical Field

[0001] The present disclosure relates to a compressor and an assembly method for the same.Background Art

[0002] A compressor provided with a compression portion that compresses a refrigerant inside a housing is known (refer to PTL 1). In the same document, a cylindrical support frame is used to adjust the axial center of the compression portion. The support frame is fixed to the housing by spot welding.Citation ListPatent Literature

[0003] [PTL 1] Japanese Unexamined Patent Application Publication No. 2003-239873Summary of InventionTechnical Problem

[0004] In PTL 1, when the compression portion is adjusted using the support frame, it is necessary to retighten and adjust the bolts that fix the support frame, which causes a problem that the work becomes complicated.

[0005] The present disclosure has been made in view of such circumstances, and an object of the present disclosure is to provide a compressor and an assembly method therefor, in which it is possible to easily perform centering of a compression portion with respect to a housing.Solution to Problem

[0006] A compressor of the present disclosure includes: a housing; a compression portion accommodated in the housing; a rotary shaft portion that drives the compression portion; a welding fixation portion that welds and fixes the compression portion to the housing; and a shim inserted between an outer peripheral surface of the compression portion and an inner peripheral surface of the housing.

[0007] An assembly method for assembling a compressor of the present disclosure is a method for assembling a compressor including a housing, a compression portion accommodated in the housing, and a rotary shaft portion that drives the compression portion, the method including: an insertion step of inserting the compression portion into the housing such that an inner peripheral surface of the housing is in contact with the compression portion; a shim attachment step of attaching a shim to a gap between an outer peripheral surface of the compression portion and the inner peripheral surface of the housing; and a welding and fixing step of welding and fixing the compression portion to the housing.Advantageous Effects of Invention

[0008] By using the shim, centering of the compression portion with respect to the housing can be easily performed.Brief Description of Drawings

[0009] Fig. 1 is a longitudinal cross-sectional view of a compressor according to an embodiment of the present disclosure. Fig. 2 is a cross-sectional view showing a lower bearing as viewed in the direction of arrow A in Fig. 1. Fig. 3 is a partially enlarged longitudinal cross-sectional view showing a periphery of a shim. Fig. 4A is a plan view showing an expanded state before the shim is bent. Fig. 4B is a plan view showing a state where the shim is bent into an L-shape. Fig. 5 is a longitudinal cross-sectional view showing a state before the rotary compression portion is inserted into the housing. Fig. 6 is a longitudinal cross-sectional view showing a state after the rotary compression portion is inserted into the housing. Fig. 7 is a plan view showing a modification example of the shim. Fig. 8 is a plan view showing a modification example of the shim. Fig. 9 is a plan view showing a modification example of the shim. Description of Embodiments

[0010] Hereinafter, an embodiment according to the present disclosure will be described with reference to the drawings.

[0011] As shown in Fig. 1, a compressor 1 is used for an air conditioner and compresses a refrigerant R, which is, for example, a gas such as carbon dioxide, in two stages. The compressor 1 is fixed to an installation surface FL via a leg portion 3. The compressor 1 includes a housing 11 and includes a rotary compression mechanism (compression portion) 12, a scroll compression mechanism 13, an electric motor 14, and a rotary shaft (rotary shaft portion) 15, which are provided inside the housing 11.

[0012] The housing 11 has a main body portion 21 having a cylindrical shape, and an upper cover portion 22 and a lower cover portion 23 that close upper and lower openings of the main body portion 21. The inside of the housing 11 forms a sealed space. The main body portion 21 of the housing 11 is manufactured by cutting a tubular material or a round rod material, and has higher dimensional accuracy than a product manufactured by bending a flat plate and welding end portions. Therefore, a welding line extending in an axial direction is not formed in the main body portion 21.

[0013] The rotary shaft 15 is provided to extend vertically along an axis X inside the housing 11. The upper end (one end) side of the rotary shaft 15 is rotatably supported by an upper bearing 31. The lower end (the other end) side of the rotary shaft 15 is rotatably supported by a lower bearing 32. The lower bearing 32 is integrally assembled with the rotary compression mechanism 12, and constitutes a rotary compression portion (compression portion) together with the rotary compression mechanism 12.

[0014] The electric motor 14 is disposed at the center of the rotary shaft 15 in the longitudinal direction and on the outer peripheral side of the rotary shaft 15, and rotates the rotary shaft 15 around the axis X. The electric motor 14 includes a rotor 38 which is fixed to the outer peripheral surface of the rotary shaft 15, and a stator 39 which is fixed to an inner wall of the main body portion 21 of the housing 11 by being shrink-fitted or the like and faces the outer peripheral surface of the rotor 38 in the radial direction with a gap therebetween.

[0015] The rotor 38 is provided with rotor passages 38a which are provided with predetermined intervals in the circumferential direction. Each rotor passage 38a penetrates the rotor 38 in the vertical direction (axis X direction). The refrigerant discharged from a rotary compression mechanism 12 flows upward through the rotor passages 38a. An oil separation plate 38b is fixed to an upper portion of the rotor 38. The oil separation plate 38b has a disk shape and is disposed to extend in the horizontal direction. The oil separation plate 38b rotates around the axis X together with the rotor 38.

[0016] A plurality of stator passages 39a are formed on the outer periphery of the stator 39 with predetermined angular intervals in the circumferential direction.

[0017] As shown in Fig. 1, an upper coil end 39b, in which the winding is folded, is located in an upper portion of the stator 39, and a lower coil end 39c, in which the winding is folded, is located in a lower portion of the stator 39. The electric motor 14 is connected to a power source via an inverter (not shown in the drawing), and rotates the rotary shaft 15 with a variable frequency.

[0018] The rotary compression mechanism 12 is provided inside the housing 11 on the lower end (the other end) side of the rotary shaft 15. The rotary compression mechanism 12 is a two-cylinder mechanism in the present embodiment, and includes an eccentric shaft portion 41 which is provided on the rotary shaft 15, a rotor 42 which is fixed to the eccentric shaft portion 41 and rotates eccentrically with respect to the axis X as the rotary shaft 15 rotates in a compression chamber C1, and a cylinder 44 in which the compression chamber C1 is formed.

[0019] The refrigerant R is supplied from the suction pipe 33 via the suction boss 36 to the compression chamber C1 formed in the cylinder 44. The refrigerant compressed in the compression chamber C1 is discharged from a rotary discharge pipe 43 to a region below the electric motor 14 in the housing 11 via the lower bearing 32.

[0020] The cylinder 44 is fixed to the lower bearing 32 from the lower side by a bolt 48. An oil pump 49, which is fixed by the bolt 48 together with the cylinder 44, is provided below the cylinder 44. Oil is sucked from an oil reservoir O1 at the lower portion of the housing 11 by the oil pump 49, passes through an oil supply hole 15a penetrated along the axis X of the rotary shaft 15, and is guided toward the upper bearing 31.

[0021] The scroll compression mechanism 13 is disposed above the electric motor 14 inside the housing 11. The scroll compression mechanism 13 includes a fixed scroll 51 fixed to the upper bearing 31, and an orbiting scroll 57 disposed below the fixed scroll 51 to face the fixed scroll 51.

[0022] The fixed scroll 51 has an end plate 52 fixed to an upper surface of the upper bearing 31, and a fixed wrap 53 protruding downward from the end plate 52. A discharge hole 52a penetrating upward and downward is formed in a central portion (in the vicinity of the axis X) of the end plate 52.

[0023] The orbiting scroll 57 is disposed to be interposed between the upper bearing 31 and the fixed scroll 51. The orbiting scroll 57 has an end plate 58 connected to the upper end side of the rotary shaft 15, and an orbiting wrap 59 protruding upward from the end plate 58.

[0024] The end plate 58 is connected to the eccentric shaft portion 56 provided at the upper end of the rotary shaft 15 via the drive bush 55, and performs an orbiting motion while being eccentric with respect to the axis X as the rotary shaft 15 rotates.

[0025] The orbiting wrap 59 meshes with the fixed wrap 53 to form a compression chamber C2 for compressing the refrigerant R between the orbiting wrap 59 and the fixed wrap 53.

[0026] A balance weight chamber 63 is formed between a recessed portion on the central side of the upper bearing 31 and the lower portion of the orbiting scroll 57. In the balance weight chamber 63, the balance weight 54 rotates together with the rotary shaft 15.

[0027] The refrigerant R, which is compressed by the rotary compression mechanism 12 and discharged into the housing 11, is sucked into the compression chamber C2 from the outer peripheral side of the scroll compression mechanism 13 and is compressed toward the central side. The compressed refrigerant R is discharged from a discharge pipe 34 to the outside of the housing 11 via the discharge hole 52a of the fixed scroll 51.

[0028] A cover 45 is provided below the upper bearing 31 to cover the upper bearing 31. The cover 45 is formed by sheet metal processing, and has a substantially conical shape that is expanded in diameter from the lower side to the upper side. The upper end of the cover 45 on the outer peripheral side is fixed to the upper bearing 31 by bolts or the like.

[0029] A suction opening 45a is provided at the lower end of the cover 45. That is, the suction opening 45a faces downward and is an annular region formed between the cover 45 and the rotary shaft 15. The space below the housing 11 and the space on the upper bearing 31 side are partitioned by the cover 45, and the refrigerant which is sucked from the suction opening 45a is guided to the scroll compression mechanism 13.

[0030] An oil level tank 60 is provided outside and below the housing 11. The oil level tank 60 is regarded as a hollow container and communicates with the inside of the housing 11 via a lower pipe 61 and an upper pressure equalization pipe 62. The oil level tank 60 measures the oil level of the oil reservoir O1 by guiding the oil from the oil reservoir O1 in the housing 11 via the lower pipe 61.

[0031] A downstream end of the oil separator oil return pipe 65 is connected to a lower side portion of the housing 11. An upstream end of the oil separator oil return pipe 65 is connected to an oil separator (not shown in the drawing). The oil separator separates the oil from the refrigerant discharged from the compressor 1, and the separated oil is returned to the oil reservoir O1 in the housing 11 via the oil separator oil return pipe 65. A height position, at which the downstream end of the oil separator oil return pipe 65 is connected to the housing 11, is set below the lower bearing 32.

[0032] An oil return pipe 67, which extends in the vertical direction while coming into contact with the inner wall of the housing 11, is provided inside the housing 11. The oil return pipe 67 is provided such that an upper end (one end) thereof is fixed to the upper bearing 31 and a lower end (the other end) thereof is positioned at the oil reservoir O1 in the lower portion of the housing 11.<Fixed structure of rotary compression portion>

[0033] Hereinafter, a fixed structure of a rotary compression portion including the lower bearing 32 and the rotary compression mechanism 12 will be described.

[0034] Fig. 2 shows a cross section of the lower bearing 32 as viewed from the side. The lower bearing 32 includes a central cylindrical portion 32a and three arm portions 32b extending in the radial direction from the cylindrical portion 32a. The respective arm portions 32b are disposed at an angle of 120° at an equal angular interval in the circumferential direction. The tips of the respective arm portions 32b are fixed to the inner surface of the housing 11 by a plug welded portion (welding fixation portion) 35 where plug welding is performed.

[0035] A shim 37 is provided between the outer peripheral surface of each of the arm portions 32b and the inner peripheral surface of the housing 11. The shim 37 fills a gap between the outer peripheral surface of each of the arm portions 32b and the inner peripheral surface of the housing 11. The shim 37 is fixed to the arm portion 32b by the bolt (fixing portion) 40.

[0036] Fig. 3 shows a partially enlarged longitudinal cross-sectional view of a position where the shim 37 is attached. As shown in the drawing, the shim 37 has an L-shape bent at a substantially right angle in a longitudinal cross-sectional view as shown in the drawing.

[0037] Fig. 4A shows an expanded state before the shim 37 is bent at an approximately right angle. The shim 37 is a metal plate-shaped body such as a steel plate hot commercial (SHPC). The thickness of the shim 37 is, for example, 0.1 mm or more and 0.6 mm or less. However, the thickness of the shim 37 is determined according to a gap between the inner peripheral surface of the housing 11 formed at the time of assembly and the outer peripheral surface of the arm portion 32b.

[0038] The shim 37 includes a main body portion 37a provided at one end, a fixing piece portion 37b provided at the other end, and a connecting portion 37c connecting the main body portion 37a and the fixing piece portion 37b.

[0039] The main body portion 37a of the shim 37 fills a gap between the inner peripheral surface of the housing 11 and the outer peripheral surface of the arm portion 32b in the attachment state shown in Fig. 3. As shown in Fig. 4A, the main body portion 37a has an arc-shaped tip, and a plug welding hole portion 37a1 having a round hole is formed in the center. Since the tip of the main body portion 37a has an arc shape, resistance is reduced when the scroll compression portion is inserted into the housing 11 at the time of assembly. As shown in Fig. 3, the plug welding hole portion 37a1 of the main body portion 37a has a shape in which the plug welded portion 35 can be secured, and the gap between the inner peripheral surface of the housing 11 and the outer peripheral surface of the arm portion 32b can be filled with the main body portion 37a in the vicinity of the periphery of the plug welded portion 35.

[0040] As shown in Fig. 3, the fixing piece portion 37b of the shim 37 is attached to an end surface that is connected to the outer peripheral surface of the arm portion 32b. As shown in Fig. 4A, a fixing hole portion 37b1 formed as a round hole is formed at the center of the fixing piece portion 37b. As shown in Fig. 3, the shim 37 is fixed to the arm portion 32b by attaching the bolt 40 to be inserted into the fixing hole portion 37b1.

[0041] As shown in Fig. 4A, the connecting portion 37c of the shim 37 is located between the main body portion 37a and the fixing piece portion 37b, and the width dimension (dimension in the right-left direction in Fig. 4A) is smaller than the main body portion 37a and the fixing piece portion 37b. Accordingly, the shim 37 can be easily bent into an L-shape. The shim 37 is bent into an L-shape around the connecting portion 37c by press working or the like, and has a shape as shown in Fig. 4B.

[0042] The compressor 1 having the above-described configuration operates as follows.

[0043] The refrigerant evaporated in an evaporator (not shown) is sucked into the compressor 1 from the suction pipe 33 via the suction boss 36, and is compressed by the rotary compression mechanism 12. The refrigerant compressed by the rotary compression mechanism 12 is discharged from the rotary discharge pipe 43 into the housing 11.

[0044] The refrigerant discharged into the housing 11 is sucked from the suction opening 45a of the cover 45, and is guided to the scroll compression mechanism 13 through a flow path in the cover 45 to be compressed. The refrigerant compressed by the scroll compression mechanism 13 is discharged from the discharge pipe 34 to an external gas cooler or condenser through the discharge hole 52a of the fixed scroll 51.<Assembling Step of Rotary Compression Portion>

[0045] The rotary compression portion is assembled as follows.

[0046] As shown in Fig. 5, after the upper bearing 31 and the stator 39 of the scroll compression mechanism 13 are assembled to the main body portion 21 of the housing 11, an assembly in which a rotary compression portion including the upper bearing 31 and the rotary compression mechanism 12, the rotary shaft 15, and the rotor 38 are integrated is inserted into the housing 11 (insertion step). Thereafter, shims 37 are attached to the respective arm portions 32b of the lower bearing 32 (shim attachment step). Fig. 5 corresponds to the upper and lower positions at the time of assembly, and is upside down from Fig. 1.

[0047] When the shim 37 is not used as in the present embodiment, an assembly jig that supports both the housing 11 side and the assembly on the rotary compression portion side in the state of Fig. 5 and inserts the rotary compression portion while aligning the axes of the rotary compression portion and the housing 11 is required. Such an assembly jig has a large size, and thus the manufacturing cost increases.

[0048] In contrast, in the present embodiment, the assembly jig as described above is not required by using only the shim 37.

[0049] The thickness of the shim 37 is, for example, 0.1 mm or more and 0.6 mm or less, and is obtained by being calculated or measured from dimensional accuracy of the inner peripheral surface of the main body portion 21 of the housing 11 and dimensional accuracy of the outer peripheral surface of the arm portion 32b of the lower bearing 32. That is, since the desired dimensional accuracy can be obtained by cutting the inner peripheral surface of the main body portion 21 and the outer peripheral surface of the arm portion 32b, the lower bearing 32 can be centered by the shim 37 having a thickness of 0.1 mm or more and 0.6 mm or less.

[0050] Then, as shown in Fig. 6, after the rotary compression portion is inserted into the housing 11, the rotary compression portion is fixed to the housing 11 by performing plug welding on the tips of the arm portions 32b of the lower bearing 32 (refer to the plug welded portion 35 in Fig. 3) (welding and fixing step).

[0051] The actions and effects of the present embodiment described above are as follows.

[0052] By inserting the shim 37 between the inner peripheral surface of the housing 11 and the outer peripheral surface of the arm portion 32b of the lower bearing 32, it is possible to accurately center the scroll compression portion with respect to the rotary shaft 15 without using an assembly jig.

[0053] The rotary compression portion is fixed to the housing 11 by providing the plug welded portion 35 on the outer peripheral surface of each of the plurality of arm portions 32b extending in the radial direction. Then, since the shim 37 is disposed around the plug welded portion 35, the welding fixation is accurately performed in a state where the rotary compression portion is centered by the shim 37.

[0054] By forming the fixing hole portion 37b1 at a position corresponding to the plug welded portion 35 in the shim 37, the plug welding can be performed. In addition, the gap can be reliably adjusted around the plug welded portion 35 by the shim 37. It is desirable that the hole diameter of the plug welding hole portion 37a1 of the shim 37 is larger than the hole diameter of the plug welded portion 35 so as not to hinder the plug welding.

[0055] The shim 37 is fixed to the lower bearing 32 by the bolt 40, and thus it is possible to avoid the shim 37 falling off the lower bearing 32 during the operation of the compressor 1.<Modification Examples>

[0056] The present embodiment can be modified as follows.

[0057] As shown in Fig. 7, the surface of the main body portion 37a of the shim 37 that comes into contact with the housing 11 may be curved to have a curved surface shape. The curved surface shape is a cylindrical surface shape corresponding to the inner peripheral surface of the housing 11. Accordingly, the main body portion 37a is easily inserted into the inner peripheral surface of the housing 11 at the time of assembly, and the assembly is improved.

[0058] Instead of the plug welding hole portion 37a1 which is a round hole as in Fig. 4A, a plug welding hole portion 37a2 that is a notch hole open toward one side (left side in the drawing) of the main body portion 37a as shown in Fig. 8 may be used. In this manner, the shim 37 can be inserted while a jig such as a pin is still inserted while the position of the plug weld hole position is adjusted.

[0059] Instead of the fixing hole portion 37b1 which is a round hole as shown in Fig. 4A, a fixing hole portion 37b2 that is a notch hole open toward one side (left side in the drawing) of the fixing piece portion 37b as shown in Fig. 9 may be used. Accordingly, the position of the shim 37 can be finely adjusted after the shim 37 is installed.

[0060] In addition, although not shown, a shim 37 may be a combination of the plug welding hole portion 37a2 shown in Fig. 8, which is a notch hole, and the fixing hole portion 37b2 shown in Fig. 9, which is a notch hole.

[0061] In the above-described embodiment, the fixation of the rotary compression portion has been described. However, the present disclosure is not limited to the rotary type compression system, and can be applied as long as the compression portion is generally fixed to the housing.

[0062] The compressor and the assembly method for assembling the compressor described in each of the embodiments described above are understood as follows, for example.

[0063] A compressor (1) according to a first aspect of the present disclosure includes: a housing (11); a compression portion (32, 12) accommodated in the housing; a rotary shaft portion (15) that drives the compression portion; a welding fixation portion (35) that welds and fixes the compression portion to the housing; and a shim (37) inserted between an outer peripheral surface of the compression portion and an inner peripheral surface of the housing.

[0064] By inserting the shim between the inner peripheral surface of the housing and the outer peripheral surface of the compression portion, it is possible to accurately center the compression portion with respect to the rotary shaft portion without using the assembly jig.

[0065] The compressor according to a second aspect of the present disclosure, in the first aspect, the compression portion includes a plurality of arm portions (32b) extending in the radial direction, the welding fixation portion is provided on an outer peripheral surface of the arm portion, and the shim is disposed around the welding fixation portion.

[0066] The compression portion is fixed to the housing by providing the welding fixation portions on the outer peripheral surfaces of the plurality of arm portions extending in the radial direction. Then, since the shim is disposed around the welding fixation portion, the welding fixation is accurately performed in a state where the compression portion is centered by the shim.

[0067] The compressor according to a third aspect of the present disclosure, in the first or second aspect, a hole portion (37a1, 37a2) is formed in the shim at a position corresponding to the welding fixation portion.

[0068] By forming the hole portion at a position corresponding to the welding fixation portion in the shim, the housing and the compression portion can be welded. In addition, the gap can be reliably adjusted around the welding fixation portion by the shim.

[0069] The compressor according to a fourth aspect of the present disclosure, in any one of the first aspect to the third aspect, the compressor further includes a fixing portion (40, 37b1, 37b2) that fixes the shim to the compression portion.

[0070] The shim is fixed to the compression portion by the fixing portion, and thus it is possible to avoid the shim falling off the compression portion during the operation of the compressor. For example, a hole portion for a bolt can be formed in the shim, and the shim can be fixed to the compression portion by the bolt.

[0071] An assembly method for assembling a compressor according to a third aspect of the present disclosure is a method for assembling a compressor including a housing, a compression portion accommodated in the housing, and a rotary shaft portion that drives the compression portion, the method including: an insertion step of inserting the compression portion into the housing such that an inner peripheral surface of the housing is in contact with the compression portion; a shim attachment step of attaching a shim to a gap between an outer peripheral surface of the compression portion and the inner peripheral surface of the housing; and a welding and fixing step of welding and fixing the compression portion to the housing.Reference Signs List

[0072] 1: Compressor 3: Leg portion 11: Housing 12: Rotary compression mechanism (compression portion) 13: Scroll compression mechanism 14: Electric motor 15: Rotary shaft (rotary shaft portion) 15a: Oil supply hole 21: Main body portion 22: Upper cover portion 23: Lower cover portion 31: Upper bearing (bearing portion) 32: Lower bearing (compression portion) 32a: Cylindrical portion 32b: Arm portion 33: Suction pipe 34: Discharge pipe 35: Plug welded portion 36: Suction boss (boss portion) 37: Shim 37a: Main body portion 37a1, 37a2: Plug welding hole portion 37b: Fixing piece portion 37b1, 37b2: Fixing hole portion 37c: Connecting portion 38: Rotor 38a: Rotor passage 38b: Oil separation plate 39: Stator 39a: Stator passage 39b: Upper coil end 39c: Lower coil end 40: Bolt (fixing portion) 41: Eccentric shaft portion 42: Rotor 43: Rotary discharge pipe 44: Cylinder 45: Cover 45a: Suction opening 48: Bolt 49: Oil pump 51: Fixed scroll 52: End plate 52a: Discharge hole 53: Fixed wrap 54: Balance weight 55: Drive bush 56: Eccentric shaft portion 57: Orbiting scroll 58: End plate 59: Orbiting wrap 60: Oil level tank 61: Lower pipe 62: Pressure equalization pipe 63: Balance weight chamber 65: Oil separator oil return pipe 67: Oil return pipe C1: Compression chamber C2: Compression chamber FL: Installation surface O1: Oil reservoir X: Axis

Claims

1. A compressor comprising: a housing; a compression portion accommodated in the housing; a rotary shaft portion that drives the compression portion; a welding fixation portion that welds and fixes the compression portion to the housing; and a shim inserted between an outer peripheral surface of the compression portion and an inner peripheral surface of the housing.

2. The compressor according to claim 1, wherein the compression portion includes a plurality of arm portions extending in a radial direction, the welding fixation portion is provided on an outer peripheral surface of the arm portion, and the shim is disposed around the welding fixation portion.

3. The compressor according to claim 2, wherein a hole portion is formed in the shim at a position corresponding to the welding fixation portion.

4. The compressor according to claim 1, further comprising: a fixing portion that fixes the shim to the compression portion.

5. An assembly method for assembling a compressor including a housing, a compression portion accommodated in the housing, and a rotary shaft portion that drives the compression portion, the method comprising: an insertion step of inserting the compression portion into the housing such that an inner peripheral surface of the housing is in contact with the compression portion; a shim attachment step of attaching a shim to a gap between an outer peripheral surface of the compression portion and the inner peripheral surface of the housing; and a welding and fixing step of welding and fixing the compression portion to the housing.

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