EP2800905B1

EP2800905B1 - Azimuthal alignment of three parts of a compressor volute

Info

Publication number: EP2800905B1
Application number: EP12820946.7A
Authority: EP
Inventors: Tomoyuki Isogai; Tetsuya Niwa; Ryu Osuka
Original assignee: Toyota Motor Corp; Otics Corp
Current assignee: Toyota Motor Corp; Otics Corp
Priority date: 2012-01-05
Filing date: 2012-12-21
Publication date: 2015-09-23
Anticipated expiration: 2032-12-21
Also published as: CN104024650A; WO2013102978A1; JP2013139755A; JP5369198B2; EP2800905A1; CN104024650B

Description

Technical Field

The present invention relates to a compressor housing used, for example, in a centrifugal compressor of an exhaust turbine supercharger.

Background Art

Such a compressor housing is disclosed, for example, in Patent Literature 1. The compressor housing of Patent Literature 1 accommodates an impeller and has a suction port for conducting air toward the impeller and a scroll passage, which annularly extends about the impeller. The compressor housing further includes a scroll member, a shroud member, and an annular member.
Hereinafter, a side of the compressor housing that is close to the suction port in the axial direction of the impeller is referred to as a distal side, and a side farther from the suction port is referred to a proximal side. The impeller is located on the proximal side of the suction port.
The scroll member has a tubular suction portion, which forms the suction port, a scroll wall portion, which forms a distal-side wall surface of the scroll passage, and an outer wall portion, which extends toward the proximal side from the scroll wall portion. The outer wall portion is located outside of the scroll passage in the radial direction of the impeller and extends in the circumferential direction of the impeller.
The shroud member has a fitting portion to be fitted to the suction portion of the scroll member and a shroud portion. The shroud portion includes a wall surface on a proximal side of the inner circumference of the scroll passage, a shroud surface facing the impeller, and a diffuser surface, which extends from the shroud surface toward the scroll passage.
The annular member includes an outer circumferential surface, which contacts the inner side of the outer wall portion of the scroll member, and a proximal-side wall surface located on the outer circumference of the scroll passage.
The scroll member is formed by die casting. The shroud member and the annular member are formed integrally by die casting and are then cut apart after being mounted to the scroll member.
In the scroll passage, air flows in the circumferential direction of the impeller from an upstream end to a downstream end. The cross-sectional area of the scroll passage increases from the upstream end toward the downstream end.
Also, a tubular discharge portion is formed integrally with the scroll member. The discharge portion is connected to the downstream end of the scroll passage to discharge air.
The scroll member and the shroud member have contact portions, which contact each other in the axial direction of the impeller, and the scroll member and the annular member have contact portions, which contact each other in the axial direction of the impeller. By causing the contact portions to contact each other, the positions of the shroud member and the annular member are determined with respect to the scroll member in the axial direction of the impeller.
The positions of the shroud member and the annular member must be determined with respect to the scroll member also in the circumferential direction of the impeller scroll member. However, Patent Literature 1 does not disclose any configuration related to position determination in the circumferential direction of the impeller.
Patent Literature 2 discloses a compressor housing in which a part that corresponds to a shroud member and a part that corresponds to an annular member are formed integrally. In the vicinity of the downstream end of the scroll passage, a positioning portion is formed in the part of the compressor housing that corresponds to the annular member. The positioning portion determines, in the circumferential direction of the impeller, the positions of the parts of the compressor housing that corresponds to the annular member and the shroud member with respect to the scroll member.
Conventionally, a positioning portion that determines the position of a shroud member with respect to a scroll member in the circumferential direction of the impeller is formed at the upstream end of a scroll passage. That is, the positioning portion is formed at a part in the scroll passage that has the smallest cross-sectional area.
Another type of conventional compressor housing has been proposed that includes a positioning portion for determining a shroud member with respect to a scroll member in the circumferential direction of an impeller and a positioning portion for determining the position of an annular member. See for instance US 6 193 463 B1 .
The positioning portions of this type of compressor housing are formed at different positions in the circumferential direction of the impeller. Thus, when assembling the shroud member and the annular member to the scroll member, a worker needs to pay attention to both of different two portions: the positioning portion for determining the position of the shroud member and the positioning portion for determining the position of the annular member. This makes the assembly of the shroud member and the annular member to the scroll member laborious.

Citation List

Patent Literature

PTL 1: Japanese Laid-Open Patent Publication No. 2011-231620
PTL 2: US Patent No. 7179051

Summary of Invention

Technical Problem

Accordingly, it is an objective of the present invention to provide a compressor housing that allows a shroud member and an annular member to be easily and accurately assembled to a scroll member.

Solution to Problem

Means for achieving the above objective and advantages thereof will now be discussed.

(1) In accordance with one aspect of the present invention, a compressor housing for accommodating an impeller is provided that includes a suction port for drawing air toward the impeller and a scroll passage, which is located about the impeller and extends in the circumferential direction of the impeller. A side in the axial direction of the impeller that is close to the suction port is defined as a distal side of the compressor housing. A side farther from the suction port is defined to a proximal side. The compressor housing includes a scroll member, a shroud member, and an annular member. The scroll member includes a tubular suction portion, which forms the suction port, a scroll wall portion, which forms a distal-side wall surface of the scroll passage, and an outer wall portion, which extends toward the proximal side from the scroll wall portion. The outer wall portion is located outside of the scroll passage in the radial direction of the impeller and extends in the circumferential direction of the impeller. The shroud member includes a fitting portion and a shroud portion. The fitting portion is fitted to the suction portion of the scroll member. The shroud portion has a first proximal-side wall surface of the scroll passage, which is located on the proximal side of the inner circumference of the scroll passage, a shroud surface, which faces the impeller, and a diffuser surface, which extends from the shroud surface toward the scroll passage. The annular member includes an outer circumferential surface and a second proximal-side wall surface of the scroll passage, which is located on the proximal side of the outer circumference of the scroll passage. The annular member is fitted to the outer wall portion of the scroll member such that the outer circumferential surface of the annular member contacts the inner side of the outer wall portion. The compressor housing is formed by assembling the scroll member, the shroud member, and the annular member together. The scroll member includes a first positioning portion, which contacts the shroud member to determine the position of the shroud member in relation to the scroll member in the circumferential direction of the impeller, and a second positioning portion, which contacts the annular member to determine the position of the annular member in relation to the scroll member in the circumferential direction of the impeller. The first positioning portion and the second positioning portion are formed at the same position in the circumferential direction of the impeller.

According to the above configuration, the first positioning portion, which determines the position of the shroud member with respect to the scroll member in the circumferential direction of the impeller, and the second positioning portion, which determines the position of the annular member with respect to the scroll member in the circumferential direction of the impeller, are formed at the same position in the circumferential direction of the impeller. That is, the first positioning portion and the second positioning portion are formed on the same plane that contains the axis of the impeller. Therefore, the positions of the shroud member and the annular member can be determined at the same position in the circumferential direction of the impeller. Therefore, the shroud member and the annular member are easily and accurately assembled to the scroll member.
Particularly, the configuration facilitates assembly when the compressor housing is manufactured by forming the shroud member and the annular member integrally, and cutting apart the shroud member and the annular member from each other after assembling the shroud member and the annular member to the scroll member.

(2) It is preferable that, in the scroll passage, air flows in the circumferential direction of the impeller from an upstream end to a downstream end of the scroll passage, the cross-sectional area of the scroll passage being increased from the upstream end toward the downstream end, and that the first positioning portion and the second positioning portion are formed at the upstream end of the scroll passage.

The first positioning portion and the second positioning portion of the scroll member contact the shroud member and the annular member, respectively. This structure is likely to create steps between components. If formed in the scroll passage, such steps will increase resistance against air flowing through the scroll passage, and thus degrades the performance of the compressor.
In this respect, the first positioning portion and the second positioning portion of the above described configuration are formed at the upstream end of the scroll passage. That is, the first positioning portion and the second positioning portion are formed at positions where the formed step has the least influence on increase in the flow resistance. Therefore, it is possible to reliably prevent the flow resistance in the scroll passage from being increased by a step formed by the first positioning portion and the second positioning portion.

(3) It is preferable that a tubular discharge portion is formed integrally with the scroll member, the discharge portion being connected to the downstream end of the scroll passage to discharge air, and that the discharge portion is connected to the scroll member at a position that is the same position as the upstream end of the scroll passage in the circumferential direction of the impeller and is offset in the axial direction of the impeller.

According to the above configuration, the length of the scroll passage in the circumferential direction of the impeller is maximized. Also, it is possible to further reliably prevent the flow resistance in the scroll passage from being increased by a step formed by the first positioning portion and the second positioning portion.

Brief Description of Drawings

[fig.1]Fig. 1 is a cross-sectional view illustrating a centrifugal compressor having a compressor housing according to one embodiment of the present invention.
[fig.2]Fig. 2 is a plan view of a scroll member, which is a part of the compressor housing of the embodiment of Fig. 1, as viewed from the side of the bearing housing.
[fig.3]Fig. 3 is a perspective view illustrating the scroll member of the embodiment of Fig. 1.
[fig.4]Fig. 4 is a perspective cross-sectional side view taken along line 4-4 of Fig. 2.
[fig.5]Fig. 5 is a perspective view illustrating a shroud member, which is a part of the compressor housing of the embodiment of Fig. 1.
[fig. 6] Fig. 6 is a plan view of the shroud member of the embodiment of Fig. 1, as viewed from the side of the suction port of the compressor housing.
[fig.7]Fig. 7 is a perspective cross-sectional side view taken along line 7-7 of Fig. 6.
[fig.8]Fig. 8 is a perspective view illustrating an annular member, which is a part of the compressor housing of the embodiment of Fig. 1.
[fig.9]Fig. 9 is a plan view of the annular member of the embodiment of Fig. 1, as viewed from the side of the suction port of the compressor housing.
[fig.10]Fig. 10 is a perspective cross-sectional side view taken along line 10-10 of Fig. 9.
[fig.11A]Fig. 11A is a perspective view illustrating the scroll member of the embodiment of Fig. 1.
[fig.11B]Fig. 11B is a perspective view illustrating the shroud member and the annular member of the embodiment of Fig. 1.
[fig.12A]Fig. 12A is a perspective view illustrating a scroll member of a comparison example.
[fig.12B]Fig. 12B is a perspective view illustrating a shroud member and an annular member of the comparison example.

Description of Embodiments

Hereinafter, with reference to the drawings, a compressor housing according to one embodiment of the present invention will be described. The compressor housing is employed in a centrifugal compressor, which forms a part of an exhaust turbine supercharger.
In the description below, the side closer to a suction port 22 in the axial direction of an impeller 8 (the left side as viewed in Fig. 1) will be referred to as a distal side of a compressor housing 1, and a side farther away from the suction port 22 (the right side as viewed in Fig. 1) will be referred to as a proximal side of the compressor housing 1. The axial direction, the radial direction, and the circumferential direction of the impeller 8 will be referred to as an axial direction, a radial direction, and a circumferential direction, respectively.
As shown in Fig. 1, the impeller 8 has a hub 81 and blades 82, which extend outward from the hub 81 in the radial direction of the impeller 8. The hub 81 has a center hole for receiving a distal end of a shaft 9. The shaft 9 is rotationally supported by a bearing in a bearing housing 100. The shaft 9 extends through the bearing, and the proximal end of the shaft 9 is coupled to a wheel (not shown).
The compressor housing 1 accommodates the impeller 8 on the proximal side. The compressor housing 1 also has a suction port 22 for drawing air toward the impeller 8 and a scroll passage 12, which is located about the impeller 8 and extends in the circumferential direction of the impeller 8. The compressor housing 1 includes a scroll member 2, a shroud member 4, and an annular member 6.
The scroll member 2 includes a main body 20 and a tubular discharge portion 35 connected to the main body 20.
The main body 20 has a tubular suction portion 21, a scroll wall portion 25, which extends radially outward from the proximal end of the suction portion 21, and an outer wall portion 27, which extends from the outer circumference of the scroll wall portion 25 toward the proximal end. The outer wall portion 27 is located outside of the scroll passage 12 in the axial direction of the impeller 8 and extends in the circumferential direction of the impeller 8.
An opening on the proximal side of the suction portion 21 functions as the suction port 22, which draws air toward the impeller 8. A locking projection 24 is formed along the entire inner circumferential surface 23 of the suction portion 21. The locking projection 24 projects radially inward from the inner circumferential surface 23.
The scroll wall portion 25 includes a proximal surface 25a located radially inward of the impeller 8 (hereinafter, referred to as an inner proximal surface), and a proximal surface 25b located radially outward of the impeller 8 (hereinafter, referred to as an outer proximal surface), and a distal-side wall surface 26, which extends between the inner proximal surface 25a and the outer proximal surface 25b. The distal-side wall surface 26 faces the scroll passage 12 and forms a distal-side wall surface of the scroll passage 12. The distal-side wall surface 26 has a semi-circular shape in cross-section.
The shroud member 4 has a substantially tubular shape and includes a fitting portion 41 and a shroud portion 43.
The fitting portion 41 has a tubular shape and press fitted in the suction portion 21 so that the outer circumferential surface thereof contacts the inner circumferential surface 23 of the suction portion 21 of the scroll member 2. The fitting portion 41 has a distal surface 42, which contacts the locking projection 24 of the suction portion 21. Causing the distal surface 42 to contact the locking projection 24 determines the position of the shroud 4 with respect to the scroll member 2 in the axial direction of the impeller 8.
The shroud portion 43 extends from the proximal end of the fitting portion 41 toward the proximal side of the compressor housing 1. A first proximal-side wall surface 44 is formed on the outer circumferential surface of the shroud portion 43. The first proximal-side wall surface 44 is located radially inward of the scroll passage 12 and forms a proximal-side wall surface of the scroll passage 12. A shroud surface 45, which faces the impeller 8, is formed on the inner circumferential surface of the shroud portion 43. A diffuser surface 46 is formed in a proximal side of the shroud portion 43. The diffuser surface 46 extends radially outward from the shroud surface 45. That is, the diffuser surface 46 extends from the shroud surface 45 toward the scroll passage 12. The first proximal-side wall surface 44 has a substantially quarter circular shape in cross-section.
Further, the shroud portion 43 has a distal surface 48, which faces the inner proximal surface 25a of the scroll wall portion 25 in the axial direction.
The annular member 6 has an outer circumferential surface 61 and an inner circumferential surface, which forms a second proximal-side wall surface 63.
The annular member 6 is press fitted in the scroll member 2 such that the outer circumferential surface 61 of the annular member 6 contacts the inner circumferential surface of the outer wall portion 27 of the scroll member 2.
The second proximal-side wall surface 63 forms a proximal-side wall surface on the outer circumference of the scroll passage 12. The second proximal-side wall surface 63 has a quarter circular shape in cross-section.
A distal surface 68 of the annular member 6 faces the outer proximal surface 25b of the scroll wall portion 25 in the axial direction.
The scroll member 2, the shroud member 4, and the annular member 6 are each formed by die casting.
With reference to Figs. 2 to 4, the structure of the scroll member 2 will now be described.
In the scroll passage 12, air flows counterclockwise from the upstream end of the scroll passage 12, which is at three o'clock position in Fig. 2, to the downstream end of the scroll passage 12, which is in a range from four o'clock position to three o'clock position in Fig. 2. As shown in Figs. 2 to 4, the distal-side wall surface 26 of the scroll wall portion 25, which forms the distal-side wall surface of the scroll passage 12, is formed to have a cross-sectional area that is enlarged toward the downstream end in the circumferential direction. That is, the cross-sectional area of the scroll passage 12 is gradually enlarged in the counterclockwise direction in Fig. 2.
As shown in Fig. 3, the scroll passage 12 is formed to have a spiral shape such that its center in cross section is shifted toward the distal end as the distance along the scroll passage 12 from the downstream end is decreased.
In the main body 20 of the scroll member 2, the downstream end of the scroll passage 12 is connected to the discharge portion 35, which extends outward. Specifically, the scroll passage 12 extends in the axial direction of the discharge portion 35 at the downstream end.
At the boundary between the upstream end and the downstream end of the scroll passage 12, a step portion 30 is formed on the scroll wall portion 25. The step portion 30 extends in the axial direction of the impeller 8. The step portion 30 has an end face that faces the downstream end of the scroll passage 12 in the circumferential direction of the impeller 8. The end face forms a first positioning portion 31 and a second positioning portion 32, which are located inside of and outside of the scroll passage 12, respectively.
The first positioning portion 31 is configured such that when the shroud member 4 contacts the first positioning portion 31, the position of the shroud member 4 is determined with respect to the scroll member 2.
The second positioning portion 32 is configured such that when the annular member 6 contacts the second positioning portion 32, the position of the annular member 6 is determined with respect to the scroll member 2.
That is, the scroll member 2 has the first positioning portion 31 and the second positioning portion 32, which are located substantially at the same position in the circumferential direction. The discharge portion 35 is connected to the main body 20 of the scroll member 2 at a position that is the same position as the upstream end of the scroll passage 12 in the circumferential direction of the impeller 8 and is offset in the axial direction of the impeller 8.
With reference to Figs. 5 to 7, the structure of the shroud member 4 will now be described.
As shown in Figs. 5 to 7, the first proximal-side wall surface 44 forms the inner circumferential wall on the proximal side of the scroll passage 12. The width of the first proximal-side wall surface 44 in the radial direction of the impeller 8 is basically increased toward the downstream end in the circumferential direction. The scroll passage 12 is formed to extend in the clockwise direction along the first proximal-side wall surface 44 from the upstream end of the scroll passage 12, which is at three o'clock position in Fig. 6, to the downstream end of the scroll passage 12, which is in a range from two o'clock position to three o'clock position in Fig. 6. The width of the first proximal-side wall surface 44 in the radial direction of the impeller 8 is increased from the upstream end of the scroll passage 12 in the clockwise direction.
However, the width of the first proximal-side wall surface 44 in the radial direction of the impeller 8 is gradually reduced from one o'clock position to three o'clock position. The distal surface 48 of the shroud member 4 is formed spirally such that the distal surface 48 is shifted toward the distal side as the distance along the scroll passage 12 from the downstream end of the scroll passage 12 is reduced. At the distal surface 48, a circumferential-direction contact surface 47 is formed at the boundary between the upstream end and the downstream end of the scroll passage 12. The circumferential-direction contact surface 47 forms a step that extends in the axial direction of the impeller 8.
Next, with reference to Figs. 8 to 10, the structure of the annular member 6 will now be described.
As shown in Figs. 8 to 10, the second proximal-side wall surface 63 forms the outer circumferential wall on the proximal side of the scroll passage 12. The width of the second proximal-side wall surface 63 in the radial direction of the impeller 8 is basically increased toward the downstream end in the circumferential direction. The scroll passage 12 is formed to extend in the clockwise direction along the second proximal-side wall surface 63 from the upstream end of the scroll passage 12, which is at three o'clock position in Fig. 9. The width of the second proximal-side wall surface 63 in the radial direction of the impeller 8 is increased from the upstream end of the scroll passage 12 in the clockwise direction of Fig 9.
The width of the distal surface 68 of the annular member 6 in the radial direction of the impeller 8 is gradually reduced toward the downstream end of the scroll passage 12. Also, the distal surface 68 is located at a position closest to the distal side at the upstream end of the scroll passage 12. Further, a part of the distal surface 68 that corresponds to the upstream end of the scroll passage 12 and a part of the second proximal-side wall surface 63 that corresponds to the downstream end of the scroll passage 12 are adjacent to each other in the circumferential direction. A part of the second proximal-side wall surface 63 that corresponds to the downstream end of the scroll passage 12 is located closer to the proximal side than a part of the distal surface 68 that corresponds to the upstream end of the scroll passage 12. That is, a circumferential-direction contact surface 67, which forms a step extending in the axial direction of the impeller 8, is formed at the boundary between a part of the distal surface 68 that corresponds to the upstream end of the scroll passage 12 and a part of the second proximal-side wall surface 63 that corresponds to the downstream end of the scroll passage 12 and is adjacent to the part of the distal surface 68 in the circumferential direction.
With reference to Figs. 11A, 11B, 12A, and 12B, operation of the above described embodiment will be described.
As shown in Fig. 11A, the first positioning portion 31 for determining the position of the shroud member 4 in relation to the scroll member 2 in the circumferential direction of the impeller 8 and the second positioning portion 32 for determining the position of the annular member 6 in relation to the scroll member 2 in the circumferential direction of the impeller 8 are located at the same position in the circumferential direction. That is, the first positioning portion 31 and the second positioning portion 32 are formed on the same plane that contains the axis of the impeller 8.
When the shroud member 4 and the annular member 6 are assembled to the scroll member 2 and the positions thereof are determined, the circumferential-direction contact surface 47 of the shroud member 4 and the circumferential-direction contact surface 67 of the annular member 6 are located at the same position in the circumferential direction. At this time, the circumferential-direction contact surface 47 of the shroud member 4 contacts the first positioning portion 31, and the circumferential-direction contact surface 67 of the annular member 6 contacts the second positioning portion 32.
Figs. 12A and 12B illustrate a comparison example in which a first positioning portion 131 and a second positioning portion 132 are located at different positions in the circumferential direction. According to the compressor housing 1 of the above described embodiment, the shroud member 4 and the annular member 6 are located at the same position in the circumferential direction, unlike the comparison example of Figs. 12 A and 12B.
In the comparison example of Figs. 12A and 12B, the second positioning portion 132 of a scroll member 102 is projected farther in the circumferential direction of the impeller 8 than the first positioning portion 131, and a discharge portion 135 exists between the first positioning portion 131 and the second positioning portion 132. Therefore, in the comparison example of Figs. 12A and 12B, a part of the scroll member 102 that includes the second positioning portion 132 is curved in accordance with the outer shape of the discharge portion 135 as illustrated in a section surrounded by a line formed by a long dash alternating with a short dash in Fig. 12A. In the above described embodiment, the first positioning portion 31 and the second positioning portion 32 are at the same position in the circumferential direction of the impeller 8. In the above described embodiment, a part of the annular member 6 is curved in accordance with the outer shape of the discharge portion 35 as illustrated in a section surrounded by the line formed by a long dash alternating with a short dash in Fig. 11B.
Further, the discharge portion 35 is connected to the main body 20 of the scroll member 2 at a position that is the same position as the upstream end of the scroll passage 12 in the circumferential direction of the impeller 8 and is offset in the axial direction of the impeller 8. Therefore, the length of the scroll passage 12 in the circumferential direction of the impeller 8 is maximized.
The shroud member 4 and the annular member 6 contact the first positioning portion 31 and the second positioning portion 32 of the scroll member 2. Steps are likely to form at positions of contact of these components. If such steps exist in a scroll passage, the steps will increase resistance against air flowing through the scroll passage, and the performance of the compressor cannot be improved.
In this respect, the first positioning portion 31 and the second positioning portion 32 of the above described embodiment are formed at the upstream end of the scroll pas sage 12. That is, the first positioning portion 31 and the second positioning portion 32 are formed at positions where the formed step has the least influence on increase in the flow resistance.
In the comparison example of Figs. 12A and 12B, the second positioning portion 132 of the scroll member 102 protrudes farther than the first positioning portion 131 in the circumferential direction of the impeller 8. Thus, the protruding part (hereinafter, referred to as an acute angle portion 138) is thin and pointed. Thus, when the scroll member 102 is formed by casting, it is difficult to fill a cavity in the mold that corresponds to the acute angle portion 138 with molten metal, which is likely to cause a defect.
In this respect, since the first positioning portion 31 and the second positioning portion 32 of above described embodiment are located at the same position in the circumferential direction of the impeller 8, no acute angle portion is formed at the upstream end of the scroll passage 12. The occurrence of defects is therefore reliably prevented.
The compressor housing of the above described embodiment has the following advantages.

(1) The compressor housing 1 accommodates the impeller 8 and has the suction port 22 for drawing air toward the impeller 8 and the scroll passage 12, which is located about the impeller 8 and extends in the circumferential direction of the impeller 8. The compressor housing 1 includes the scroll member 2, the shroud member 4, and the annular member 6. The scroll member 2 includes the tubular suction portion 21, which forms the suction port 22, the scroll wall portion 25, which forms the distal-side wall surface of the scroll passage 12, and the outer wall portion 27, which extends from the scroll wall portion 25 toward the proximal side. The outer wall portion 27 is located radially outside of the scroll passage 12 and extends in the circumferential direction of the impeller 8. The shroud member 4 has the fitting portion 41 and the shroud portion 43. The fitting portion 41 is fitted to the suction portion 21 of the scroll member 2. The shroud portion 43 has the first proximal-side wall surface 44, which is a wall surface on the proximal side of the inner circumference of the scroll passage 12, the shroud surface 45, which faces the impeller 8, and the diffuser surface 46, which extends from the shroud surface 45 toward the scroll passage 12. The annular member 6 has the outer circumferential surface 61, which contacts the inner circumferential surface of the outer wall portion 27 of the scroll member 2, and the second proximal-side wall surface 63, which forms the proximal-side wall surface in the outer circumference of the scroll passage 12. The scroll member 2 has the first positioning portion 31, which contacts the shroud member 4 to determine the position of the shroud member 4 in relation to the scroll member 2 in the circumferential direction of the impeller 8, and the second positioning portion 32, which contacts the annular member 6 to determine the position of the annular member 6 in relation to the scroll member 2 in the circumferential direction of the impeller 8. The first and second positioning portions 31, 32 are located at the same position in the circumferential direction of the impeller 8. This allows the shroud member 4 and the annular member 6 to be easily and accurately assembled to the scroll member 2.
(2) The scroll passage 12 includes the upstream end and the downstream end in the circumferential direction of the impeller 8, and the cross-sectional area of the scroll passage 12 decreases from the upstream end toward the downstream end. The tubular discharge portion 35 is formed integrally with the main body 20 of the scroll member 2. The discharge portion 35 is connected to the downstream end of the scroll passage 12 to discharge air. The first positioning portion 31 and the second positioning portion 32 are formed at the upstream end, at which the scroll passage 12 has the smallest cross-sectional area. Specifically, the discharge portion 35 is connected to the main body 20 of the scroll member 2 at a position that is the same position as the upstream end of the scroll passage 12 in the circumferential direction of the impeller 8 and is offset in the axial direction of the impeller 8. This configuration reliably prevents the flow resistance in the scroll passage 12 from being increased by a step that could be formed by the first positioning portion 31 and the second positioning portion 32.

The compressor housing according to the present invention is not to be restricted to configurations shown in the above embodiment, but may be modified as shown below.
In the above described embodiment, the shroud member 4 and the annular member 6 are formed by die casting and then assembled to the scroll member 2. Instead of this configuration, a shroud member and an annular member may be formed integrally as in the case of the compressor housing disclosed in Patent Literature 1, and the integrated component is assembled to a scroll member and then cut into a shroud member and an annular member. This modification also reliably facilitates the assembly as in the case of the above described embodiment.
In the above embodiment, the discharge portion 35 is connected to the main body 20 of the scroll member 2 at a position that is the same position as the upstream end of the scroll passage 12 in the circumferential direction of the impeller 8 and is offset in the axial direction of the impeller 8. This arrangement of the scroll passage 12 at the upstream end is preferable for maximizing the length of the scroll passage 12 in the circumferential direction of the impeller 8. However, the present invention is not limited to this configuration. For example, the upstream end of the scroll passage may be formed at two o'clock position in Fig. 2, and may be located at a position different from the connection portion in the circumferential direction of the impeller 8.
In the above described embodiment, the first positioning portion 31 and the second positioning portion 32 are formed at the upstream end, at which the scroll passage 12 has the smallest cross-sectional area. This configuration prevents the flow resistance in the scroll passage 12 from being increased by a step that could be formed by the first positioning portion 31 and the second positioning portion 32. However, the present invention is not limited to this configuration. If such an increase in the flow resistance is negligible, the first positioning portion 31 and the second positioning portion 32 may formed in the scroll passage 12.

Reference Signs List

1: Compressor Housing
12: Scroll Passage
2: Scroll Member
21: Suction Portion
22: Suction Port
25: Scroll Wall Portion
26: Distal-Side Wall Surface
27: Outer Wall Portion
31: First Positioning Portion
32: Second Positioning Portion
35: Discharge Portion
4: Shroud Member
41: Fitting Portion
43: Shroud Portion
44: First Proximal-Side Wall Surface
45: Shroud Surface
46: Diffuser Surface
6: Annular Member
61: Outer Circumferential Surface
63: Second Proximal-Side Wall Surface
8: Impeller

Claims

A compressor housing for accommodating an impeller, the compressor housing comprising a suction port for drawing air toward the impeller and a scroll passage, which is located about the impeller and extends in the circumferential direction of the impeller, wherein a side in the axial direction of the impeller that is close to the suction port is defined as a distal side of the compressor housing, and a side farther from the suction port is defined to a proximal side, the compressor housing being characterized by:
a scroll member (2) having a tubular suction portion, which forms the suction port, a scroll wall portion, which forms a distal-side wall surface of the scroll passage, and an outer wall portion, which extends toward the proximal side from the scroll wall portion, the outer wall portion being located outside of the scroll passage in the radial direction of the impeller and extending in the circumferential direction of the impeller;

a shroud member (4) having a fitting portion and a shroud portion, wherein the fitting portion is fitted to the suction portion of the scroll member, and the shroud portion has a first proximal-side wall surface of the scroll passage, which is located on the proximal side of the inner circumference of the scroll passage, a shroud surface, which faces the impeller, and a diffuser surface, which extends from the shroud surface toward the scroll passage; and

an annular member (6), which includes an outer circumferential surface and a second proximal-side wall surface of the scroll passage, which is located on the proximal side of the outer circumference of the scroll passage, the annular member being fitted to the outer wall portion of the scroll member such that the outer circumferential surface of the annular member contacts the inner side of the outer wall portion,

wherein

the compressor housing is formed by assembling the scroll member, the shroud member, and the annular member together, and

the scroll member includes a first positioning portion (31), which contacts the shroud member to determine the position of the shroud member in relation to the scroll member in the circumferential direction of the impeller, and a second positioning portion (32), which contacts the annular member to determine the position of the annular member in relation to the scroll member in the circumferential direction of the impeller,

the compressor housing being characterised by

the first positioning portion and the second positioning portion being formed at the same position in the circumferential direction of the impeller.
The compressor housing according to claim 1, characterized in that in the scroll passage, air flows in the circumferential direction of the impeller from an upstream end to a downstream end of the scroll passage, the cross-sectional area of the scroll passage being increased from the upstream end toward the downstream end, and the first positioning portion and the second positioning portion are formed at the upstream end of the scroll passage.
The compressor housing according to claim 2, characterized in that a tubular discharge portion is formed integrally with the scroll member, the discharge portion being connected to the downstream end of the scroll passage to discharge air, and the discharge portion is connected to the scroll member at a position that is the same position as the upstream end of the scroll passage in the circumferential direction of the impeller and is offset in the axial direction of the impeller.