Compressor housing for turbocharger

Abstract

To provide a compressor housing for a turbocharger, capable of achieving improvement of adhesion prevention effect of a deposit by improving cooling effect of a diffuser surface, and achieving improvement of productivity.SOLUTION: A compressor housing 1 for a turbocharger is dividedly formed by a plurality of pieces. A refrigerant flow passage 5 formed in a circumferential direction along a diffuser part 30 is an annular space 50 which is partitioned by a first flow channel formation part 51 including an intake port side wall surface 55 of the refrigerant flow passage 5 formed in a first piece 2, and a second flow channel formation part 52 including a diffuser passage side wall surface 58 of the refrigerant flow passage 5 formed in a position facing the first flow channel formation part 51 in a second piece 3. The diffuser passage side wall surface 58 of the refrigerant flow passage 5 extends in parallel to a radial direction X in a cross section including a rotary shaft 13a of a compressor impeller 13, and an average size S in the radial direction X in the space 50 forming the refrigerant flow passage 5 is larger than an average size T in an axial direction Y in the space 50.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a compressor housing for a turbocharger.

Background Art

[0002] A turbocharger mounted on an internal combustion engine such as an automobile has a compressor impeller and a turbine impeller, and these are housed in a housing. The compressor impeller is arranged in an air flow path formed inside the housing. The air flow path is provided with an intake port for sucking air toward the compressor impeller, a diffuser passage through which the air discharged from the compressor impeller passes and is compressed, and a scroll chamber into which the compressed air passing through the diffuser passage flows and discharges the compressed air to the internal combustion engine side.

[0003] And, some internal combustion engines such as automobiles are provided with a blow-by gas reflux device (hereinafter referred to as PCV) that refluxes the blow-by gas generated in the crankcase to the intake passage to purify the inside of the crankcase and the head cover. In this case, the oil (oil mist) contained in the blow-by gas may flow out from the PCV to the intake passage on the upstream side of the compressor in the turbocharger.

[0004] At this time, when the outlet air pressure of the compressor is high, its air temperature also becomes high. Therefore, the oil flowing out from the PCV may deposit as a deposit on the diffuser surface of the compressor housing, the surface of the center housing facing it, etc. due to concentration and high viscosity caused by evaporation. And, the diffuser passage may be narrowed by the deposited deposit, leading to a decrease in the performance of the turbocharger and further a decrease in the output of the internal combustion engine.

[0005] Conventionally, in order to prevent the deposition of deposits in the diffuser passage as described above, the outlet air temperature of the compressor has been suppressed to a certain extent. Therefore, the performance of the turbocharger could not be fully exerted, and the output of the internal combustion engine could not be sufficiently increased.

[0006] In Patent Document 1, in order to prevent the deposition of deposits in the diffuser passage, a configuration is disclosed in which a refrigerant is circulated through a refrigerant flow path provided in the inner wall portion of the housing to cool the compressed air passing through the air flow path in the housing and suppress the temperature rise.

Prior Art Document

Patent Document

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] As a method of forming a housing having a refrigerant flow path in the inner wall portion, gravity casting using a sand core can be considered. According to this method, the degree of freedom in shape is high, and it can cope with complex shapes. However, since the sand core has low strength, it is necessary to have a shape with a certain thickness so as not to break during casting, and the cross-sectional area of the formed refrigerant flow path tends to be large. And when the cross-sectional area of the refrigerant flow path becomes large, the flow velocity of the refrigerant flowing through the refrigerant flow path decreases, so the cooling effect of the compressed air passing through the air flow path in the housing is reduced. Also, in order to enhance the cooling effect, it is preferable to make the refrigerant flow path have a thin shape along the diffuser passage. However, as described above, since the sand core has low strength, it is difficult to make it have a thin shape. In addition, casting using a sand core has a long casting cycle, and sand removal work and inspection work for sand residue are required to remove the sand core, so the number of manufacturing steps increases and productivity decreases.

[0009] The present invention has been made in view of such a background, and aims to provide a compressor housing for a turbocharger in which the cooling effect of the diffuser surface is enhanced to improve the deposit adhesion prevention effect and the productivity is improved.

Means for Solving the Problems

[0010] One aspect of the present invention is a compressor housing for a turbocharger configured to accommodate a compressor impeller and be attached to a center housing, an intake port forming portion that forms an intake port for sucking air toward the compressor impeller, a shroud portion that surrounds the compressor impeller in the circumferential direction and has a shroud surface facing the compressor impeller, a diffuser portion formed in the circumferential direction on the outer peripheral side of the compressor impeller and forming a diffuser passage for compressing the air discharged from the compressor impeller, a scroll chamber forming portion that forms a scroll chamber for guiding the compressed air that has passed through the diffuser passage to the outside, a refrigerant flow path formed in the circumferential direction along the diffuser portion and through which a refrigerant for cooling the diffuser portion flows, and having the compressor housing for the turbocharger is divided into a plurality of pieces including a first piece having at least a part of the scroll chamber forming portion and the intake port forming portion, and a second piece having at least a part of the scroll chamber forming portion, a part of the shroud portion, and the diffuser portion, the refrigerant flow path is formed as an annular space partitioned by a first flow path forming portion including the intake port side wall surface of the refrigerant flow path formed in the first piece and a second flow path forming portion including the diffuser passage side wall surface of the refrigerant flow path formed at a position facing the first flow path forming portion in the second piece, The first flow path forming portion and the second flow path forming portion are fitted to each other at an inner peripheral seal portion that seals the inner peripheral side of the refrigerant flow path and an outer peripheral seal portion that seals the outer peripheral side of the refrigerant flow path. In a cross section including the rotation axis of the compressor impeller, the side wall surface of the diffuser passage in the second flow path forming portion extends parallel to the radial direction, and the average size S in the radial direction in the space forming the refrigerant flow path is larger than the average size T in the axial direction in the space. This is in the compressor housing for a turbocharger.

Advantages of the Invention

[0011] According to the compressor housing for a turbocharger of the above-described embodiment, the side wall surface of the diffuser passage of the refrigerant flow path extends parallel to the radial direction, and the average size S in the radial direction in the space forming the refrigerant flow path is larger than the average size T in the axial direction in the space. As a result, by securing a wide side wall surface of the diffuser passage of the refrigerant flow path, the heat receiving area from the diffuser surface to the refrigerant flowing through the refrigerant flow path can be increased, and by reducing the cross-sectional area of the refrigerant flow path, the flow velocity of the refrigerant in the refrigerant flow path can be increased. As a result, the cooling effect of the diffuser surface is enhanced, and the effect of preventing the adhesion of deposits is improved. Further, since the compressor housing for a turbocharger is formed by dividing it into a plurality of pieces, it is not necessary to use a core when casting, so that the work of removing the core and the inspection work for core residues are not required, and the productivity is improved.

[0012] As described above, according to the present invention, it is possible to provide a compressor housing for a turbocharger in which the cooling effect of the diffuser surface is enhanced, the effect of preventing the adhesion of deposits is improved, and the productivity is improved.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0014] In this specification, the "circumferential direction" refers to the rotation direction of the compressor impeller, the "axial direction" refers to the direction of the rotation axis of the compressor impeller, and the "radial direction" refers to the radial direction of a virtual circle centered on the rotation axis of the compressor impeller. The outer radial direction refers to the direction of a straight line extending from the center of the virtual circle toward the circumference.

[0015] It is preferable that the average radial size S in the space forming the refrigerant flow path and the average axial size T in the space satisfy the relationship of 1 < S / T ≤ 9. In this case, since the cross-sectional area of the refrigerant flow path does not become too small, the flow rate of the refrigerant in the refrigerant flow path can be maintained, and the cooling effect can be further improved.

[0016] It is preferable that the side wall surface of the diffuser passage in the second flow path forming portion extends in the radial direction parallel to the entire circumference. In this case, since a wide side wall surface of the diffuser passage can be ensured, the cooling effect by the refrigerant flowing through the refrigerant flow path can be further improved.

[0017] The second flow path forming portion in the second piece is formed in a concave shape. It is preferable that the side wall surface of the diffuser passage of the refrigerant flow path is formed by the bottom surface of the second flow path forming portion having the concave shape. In this case, since the side wall surface of the diffuser passage of the refrigerant flow path can be formed at a position closer to the diffuser surface, the cooling effect by the refrigerant flowing through the refrigerant flow path can be further improved.

[0018] The inner peripheral seal portion is formed by press-fitting an inner peripheral press-fitting portion formed on the first piece into the inner peripheral side of an inner peripheral press-fitted portion formed on the second piece, and the outer peripheral seal portion is preferably formed by press-fitting an outer peripheral press-fitting portion formed on the first piece into the inner peripheral side of an outer peripheral press-fitted portion formed on the second piece. In this case, since the inner peripheral seal portion and the outer peripheral seal portion can maintain the sealing performance even if the thicknesses of the inner peripheral press-fitted portion and the outer peripheral press-fitted portion are relatively thin, the formation region of the refrigerant flow path can be increased in the radial direction. As a result, the side wall surface of the diffuser passage of the refrigerant flow path can be widened, and the cooling effect by the refrigerant flowing through the refrigerant flow path can be further improved.

[0019] (Embodiment 1) Hereinafter, an embodiment of the compressor housing for a turbocharger will be described with reference to FIGS. 1 to 4. As shown in FIG. 1, a compressor housing 1 for a turbocharger houses a compressor impeller 13 and includes an intake port forming portion 10, a shroud portion 20, a diffuser portion 30, a scroll chamber forming portion 120, and a refrigerant flow path 5. The intake port forming portion 10 forms an intake port 11 for sucking air toward the compressor impeller 13. The shroud portion 20 surrounds the compressor impeller 13 in the circumferential direction and has a shroud surface 21 facing the compressor impeller 13. The diffuser portion 30 is formed in the circumferential direction on the outer peripheral side of the compressor impeller 13 and forms a diffuser passage 15 through which the air discharged from the compressor impeller 13 passes and is compressed. The scroll chamber forming portion 120 forms a scroll chamber 12 for guiding the compressed air that has passed through the diffuser passage 15 to the outside. The refrigerant flow path 5 is formed in the circumferential direction along the diffuser portion 30 and allows a refrigerant for cooling the diffuser portion 30 to flow therethrough.

[0020] The compressor housing 1 for a turbocharger is divided into a plurality of pieces including a scroll piece 2 as a first piece including at least a part of the scroll chamber forming portion 120 and the intake port forming portion 10, and a shroud piece 3 which is a second piece having at least a part of the scroll chamber forming portion 120, a part of the shroud portion 20, and the diffuser portion 30.

[0021] Also, as shown in FIG. 1, the refrigerant flow path 5 is formed as an annular space 50 partitioned by a first flow path forming portion 51 formed in the scroll piece 2 and a second flow path forming portion 52 formed at a position facing the first flow path forming portion 51 in the shroud piece 3. The first flow path forming portion 51 includes at least the intake port side wall surface 55 of the refrigerant flow path 5, and the second flow path forming portion 52 includes at least the diffuser passage side wall surface 58 of the refrigerant flow path 5. The first flow path forming portion 51 and the second flow path forming portion 52 are fitted to each other at an inner peripheral seal portion 53 that seals the inner peripheral side of the refrigerant flow path 5 and an outer peripheral seal portion 54 that seals the outer peripheral side of the refrigerant flow path 5.

[0022] Then, as shown in FIG. 2, in a cross section including the rotation axis 13a of the compressor impeller 13, the diffuser passage side wall surface 58 of the refrigerant flow path 5 extends parallel to the radial direction X, and the average size S in the radial direction X in the space 50 forming the refrigerant flow path 5 is larger than the average size T in the axial direction Y in the space 50.

[0023] Hereinafter, the compressor housing 1 for a turbocharger according to the present embodiment will be described in detail. As shown in FIG. 1, the compressor housing 1 for a turbocharger is composed of a plurality of pieces 2, 3, 4 formed as separate members from each other. In the first embodiment, the compressor housing 1 for a turbocharger is formed by being divided into a scroll piece 2 as the first piece, a shroud piece 3 as the second piece, and an outer peripheral annular piece 4 as the third piece. And the compressor housing 1 for a turbocharger is attached to the seal plate of the center housing in which a bearing mechanism for bearing a shaft 14 to which a compressor impeller 13 is attached at one end is housed.

[0024] As shown in FIG. 1, the scroll piece 2 as the first piece has an intake port forming portion 10, a part of the shroud portion 20, a first scroll chamber forming portion 121, an outer peripheral portion 125, and a first flow path forming portion 51. The intake port forming portion 10 is formed in a cylindrical shape and penetrates the scroll piece 2 in the axial direction Y. A part of the shroud portion 20 forms a part of the shroud surface 21 facing the compressor impeller 13. The first scroll chamber forming portion 121 constitutes the wall surface on the intake port side Y1 in the scroll chamber 12. As shown in FIG. 1, the outer peripheral portion 125 is located on the diffuser passage side Y2 opposite to the intake port side Y1 of the first scroll chamber forming portion 121, and forms the outer peripheral portion 125 of the compressor housing 1 for a turbocharger. And an outer peripheral annular piece 4 is attached inside the outer peripheral portion 125.

[0025] As shown in FIGS. 1 and 2, the first flow path forming portion 51 in the scroll piece 2 is configured to form a refrigerant flow path 5 together with a second flow path forming portion 52 described later. And the first flow path forming portion 51 has an inner peripheral press-fitting portion 53a, an outer peripheral press-fitting portion 54a, and an intake port side wall surface 55. The inner peripheral press-fitting portion 53a forms an inner peripheral seal portion 53 described later, the outer peripheral press-fitting portion 54a forms an outer peripheral seal portion 54 described later, and the intake port side wall surface 55 is the wall surface on the intake port side Y1 in the refrigerant flow path 5. In the present embodiment, the intake port side wall surface 55 is a flat surface extending in the radial direction X.

[0026] Also, as shown in FIGS. 1 and 2, the inner peripheral press-fitting portion 53a extends from the shroud surface 21 toward the intake port side Y1. The inner peripheral press-fitting portion 53a forms a cylindrical surface facing radially outward, and is press-fitted inside the inner peripheral press-fitted portion 53b of the shroud piece 3 described later. The inner peripheral press-fitting portion 53a and the inner peripheral press-fitted portion 53b are in contact with each other in the entire circumferential direction to form the inner peripheral seal portion 53. Note that the radially inner side of the inner peripheral press-fitting portion 53a constitutes a part of the shroud surface 21 facing the compressor impeller 13.

[0027] Also, as shown in FIGS. 1 and 2, the outer peripheral press-fitting portion 54a extends from the intake port side wall surface 55 toward the intake port side Y1. The outer peripheral press-fitting portion 54a forms a cylindrical surface facing radially outward, and is press-fitted inside the outer peripheral press-fitted portion 54b of the shroud piece 3 described later. The outer peripheral press-fitting portion 54a and the outer peripheral press-fitted portion 54b are in contact with each other in the entire circumferential direction to form the outer peripheral seal portion 54.

[0028] Note that the tightening allowance of the inner peripheral seal portion 53 and the outer peripheral seal portion 54 is not particularly limited, and can be appropriately determined in consideration of the stress generated in the inner peripheral seal portion 53 and the outer peripheral seal portion 54. In this embodiment, the tightening allowances of both are the same size.

[0029] A sealing material may be interposed between one or both of the inner peripheral seal portion 53 and the outer peripheral seal portion 54. The type of the sealing material is not particularly limited, but a material having quick-drying property is preferable. For example, a sealing material used as a liquid gasket can be used.

[0030] As shown in FIGS. 1 and 2, the scroll piece 2 has a refrigerant supply portion 22 and a refrigerant discharge portion 23 which are formed by through holes penetrating the first flow path forming portion 51 and communicating with the refrigerant flow path 5. The refrigerant supply portion 22 supplies refrigerant to the refrigerant flow path 5, and the refrigerant discharge portion 23 is configured to discharge the refrigerant. In this embodiment, the refrigerant supply portion 22 and the refrigerant discharge portion 23 extend from the refrigerant flow path 5 toward the intake port side Y1, and bend radially outward in the vicinity of the intake port 11.

[0031] As shown in FIGS. 1 and 2, the scroll piece 2 has a first opposing portion 16 that is radially outside the outer peripheral seal portion 54 and is located inside the scroll chamber 12. The first opposing portion 16 is a wall surface that faces the shroud piece 3 and is parallel to the radial direction.

[0032] As shown in FIG. 1, in this embodiment, the intake port forming portion 10 includes an inducer treatment portion 17. The inducer treatment portion 17 is located on the diffuser passage side Y2 of the inner peripheral surface of the intake port forming portion 10. As it extends toward the diffuser passage side Y2 to guide the air sucked in from the intake port 11 to the compressor impeller 13, the diameter gradually decreases.

[0033] On the other hand, as shown in FIG. 1, the shroud piece 3 as the second piece has a second scroll chamber forming portion 122, a part of the shroud portion 20, a first diffuser portion 35, and a second flow path forming portion 52. The shroud piece 3 is annular as a whole.

[0034] As shown in FIG. 1, the second scroll chamber forming portion 122 in the shroud piece 3 forms the inner peripheral side wall surface of the scroll chamber 12. A part of the shroud portion 20 forms a part of the shroud surface 21 that faces the compressor impeller 13. The first diffuser portion 35 forms a diffuser surface 34 that extends from the shroud surface 21 toward the scroll chamber 12.

[0035] In this embodiment, the diffuser surface 34 is a flat surface that extends in the radial direction X. The first diffuser portion 35 and the second diffuser portion 36 formed on the seal plate of the center housing together form the diffuser portion 30. The second diffuser portion 36 has an opposing surface 37 that faces the diffuser surface 34 of the first diffuser portion 35 at a predetermined distance. And the space between the diffuser surface 34 and the opposing surface 37 is the diffuser passage 15.

[0036] And, as shown in FIG. 1, the second flow path forming portion 52 in the shroud piece 3 is configured to form the refrigerant flow path 5 together with the above-described first flow path forming portion 51, and is provided on the radially inner side of the second scroll chamber forming portion 122. As shown in FIG. 2, the second flow path forming portion 52 has a concave shape recessed on the diffuser passage side Y2, and a space 50 that constitutes the refrigerant flow path 5 is formed between the second flow path forming portion 52 and the first flow path forming portion 51.

[0037] As shown in FIG. 2, the second flow path forming portion 52 includes an outer peripheral side wall surface 56, an inner peripheral side wall surface 57, a diffuser passage side wall surface 58, an inner peripheral press-fitting portion 53b, and an outer peripheral press-fitting portion 54b. The outer peripheral side wall surface 56 in the shroud piece 3 is a wall surface on the outer peripheral side located on the radially outer side in the annular refrigerant flow path 5. In the present embodiment, the outer peripheral side wall surface 56 in the shroud piece 3 has a cylindrical shape extending from the outer peripheral edge of the diffuser passage side wall surface 58 to the intake port side Y1.

[0038] As shown in FIG. 2, the diffuser passage side wall surface 58 forms the bottom surface of the concave second flow path forming portion 52. In the present embodiment, the entire area of the diffuser passage side wall surface 58 is a plane extending in the radial direction X and is parallel to the diffuser surface 34. Also, the distance H in the axial direction Y between the diffuser passage side wall surface 58 and the diffuser surface 34 can enhance the cooling effect as it becomes smaller, but if it is too small, there is a risk of refrigerant leakage due to shrinkage cavities, so it is preferable to ensure that H is about 3 mm.

[0039] As shown in FIG. 2, the inner peripheral press-fitting portion 53b extends from the inner peripheral edge of the diffuser passage side wall surface 58 to the intake port side Y1 and forms the inner peripheral side wall of the concave second flow path forming portion 52. The outer peripheral press-fitting portion 54b extends from the outer peripheral side wall surface 56 to the intake port side Y1 and forms the outer peripheral side wall of the concave second flow path forming portion 52. The inner peripheral press-fitting portion 53b and the outer peripheral press-fitting portion 54b have a cylindrical surface extending parallel to the rotation axis 13a. And, the radially outer surface of the outer peripheral press-fitting portion 54b forms the second scroll chamber forming portion 122.

[0040] The shroud piece 3 has a second opposing portion 26, which is a wall surface parallel to the radial direction and faces the scroll piece 2, at an end located on the intake port side Y1 with respect to the outer peripheral press-fitting portion 54b. The second opposing portion 26 of the shroud piece 3 abuts against the first opposing portion 16 of the scroll piece 2 to form a contact portion 60. And a refrigerant flow path 5 is formed between the first flow path forming portion 51 and the second flow path forming portion 52.

[0041] As shown in FIGS. 1 and 2, the refrigerant flow path 5 has an elongated vertical shape that is slender in the radial direction X in a cross section including the rotation axis 13a of the compressor impeller 13. And as shown in FIG. 2, the average size S in the radial direction X in the space 50 forming the refrigerant flow path 5 is larger than the average size T in the axial direction Y in the space 50. Note that the average size S is the average value of the sizes in the radial direction X over the entire area of the space 50 forming the refrigerant flow path 5. Also, the average size T is the average value of the sizes in the axial direction Y over the entire area of the space 50 forming the refrigerant flow path 5. The method of calculating the average value is not limited, but for example, it can be calculated as the value of half of the sum of the maximum value and the minimum value.

[0042] It is preferable that the average size S in the radial direction X in the space 50 and the average size T in the axial direction Y in the space 50 satisfy 1 < S / T and further S / T ≦ 9. When S / T is 1 or less, the refrigerant flow path 5 does not have an elongated vertical shape that is slender in the radial direction X in a cross section including the rotation axis 13a. And when S / T is larger than 9, the refrigerant flow path 5 becomes excessively thin in the axial direction Y in a cross section including the rotation axis 13a, and it becomes difficult to ensure the flow rate of the refrigerant flowing through the refrigerant flow path 5. In the first embodiment, S / T = 6.

[0043] The state of the refrigerant flow in the refrigerant flow path 5 can be estimated based on the Reynolds number Re. The Reynolds number Re is defined by the following formula (1).

[0044]

Equation

[0045] When the Reynolds number Re is less than 2300, the refrigerant becomes laminar flow. When it is between 2300 and 4000, the refrigerant can be either laminar flow or turbulent flow. When it is greater than 4000, the refrigerant becomes turbulent flow.

[0046] In the first embodiment, the average size T in the axial direction Y in the space 50 is used as the representative length in the Reynolds number Re, and the Reynolds number Re can be calculated to estimate the flow state of the refrigerant in the refrigerant flow path 5. When the velocity V of the refrigerant is constant, the smaller the average size T in the axial direction Y in the space 50, the smaller the Reynolds number Re can be made, and the refrigerant flow can be made laminar.

[0047] On the other hand, if the average size T in the axial direction Y in the space 50 is made excessively small, the cross-sectional area of the refrigerant flow path 5 becomes too small, and the flow rate decreases too much to obtain a sufficient cooling effect. In the first embodiment, by setting 1 < S / T ≤ 9, it is possible to prevent the cross-sectional area of the refrigerant flow path 5 from becoming too small and ensure the flow rate of the refrigerant in the refrigerant flow path 5 for obtaining a sufficient cooling effect.

[0048] As shown in FIG. 1, the outer peripheral annular piece 4 as the third piece has a third scroll chamber forming portion 123 and an outer peripheral annular piece insertion portion 41. The third scroll chamber forming portion 123 constitutes the outer peripheral wall surface in the scroll chamber 12. The outer peripheral annular piece insertion portion 41 is inserted inside the outer peripheral portion 125.

[0049] Next, a method for manufacturing the compressor housing 1 for a turbocharger according to the present embodiment will be described. First, in the molding step, the scroll piece 2 and the shroud piece precursor 3a shown in FIG. 3 are individually manufactured by die casting. The shroud piece precursor 3a is in a state where the shroud piece 3 and the outer peripheral annular piece 4 are connected by a connecting portion 4a. The groove-shaped space 50 in the shroud piece precursor 3a is formed by die casting when the shroud piece precursor 3a is molded.

[0050] Note that the inner circumferential press-fitting portion 53a and the outer circumferential press-fitting portion 54a of the scroll piece 2, and the inner circumferential press-fitted portion 53b and the outer circumferential press-fitted portion 54b of the shroud piece 3 are machined to improve the forming accuracy. In this embodiment, the refrigerant supply portion 22 and the refrigerant discharge portion 23 formed by the through holes in the scroll piece 2 shown in FIGS. 1 and 2 are formed by machining. On the other hand, the inner circumferential surface 20a of the scroll piece 2 is cylindrical, and the shroud surface 21 (see FIG. 1) is not formed.

[0051] Next, in the assembling process, as shown in FIG. 3, with the phases of the scroll piece 2 and the shroud piece precursor 3a aligned, they are moved in the direction indicated by the arrow P. Then, as shown in FIG. 4, the inner circumferential press-fitting portion 53a of the scroll piece 2 is press-fitted into the inner circumferential press-fitted portion 53b of the shroud piece precursor 3a, the outer circumferential press-fitting portion 54a of the scroll piece 2 is press-fitted into the outer circumferential press-fitted portion 54b of the shroud piece precursor 3a, and the outer circumferential annular piece insertion portion 41 of the shroud piece precursor 3a is press-fitted inside the outer peripheral portion 125 of the scroll piece 2. Note that a slight gap C exists between the first scroll chamber forming portion 121 and the third scroll chamber forming portion 123 so that they do not contact each other. As a result, the first opposing portion 16 and the second opposing portion 26 surely come into contact with each other.

[0052] Then, when the inner circumferential press-fitting portion 53a of the scroll piece 2 is press-fitted into the inner circumferential press-fitted portion 53b of the shroud piece 3 to form the inner circumferential seal portion 53, and the outer circumferential press-fitting portion 54a of the scroll piece 2 is press-fitted into the outer circumferential press-fitted portion 54b of the shroud piece 3 to form the outer circumferential seal portion 54. Thereby, the space between the first flow path forming portion 51 and the second flow path forming portion 52 is sealed to form the refrigerant flow path 5. In this embodiment, the inner circumferential surface 20a of the scroll piece 2 and a part of the shroud piece precursor 3a shown in FIG. 4 are machined to form the shroud surface 21.

[0053] Thereafter, as a separation step, the connecting portion 4a of the shroud piece precursor 3a shown in FIG. 4 is removed by machining, and the shroud piece 3 and the outer peripheral annular piece 4 are separated from each other as shown in FIG. 1. Thereby, the compressor housing 1 for a turbocharger is completed.

[0054] And in the compressor housing 1 for a turbocharger, a refrigerant introduction pipe and a refrigerant discharge pipe (not shown) are connected to a refrigerant supply portion 22 and a refrigerant discharge portion 23 that communicate with the refrigerant flow path 5 shown in FIGS. 1 and 2, and the refrigerant is caused to flow through the refrigerant flow path 5 via these pipes, whereby the diffuser surface 34 can be cooled.

[0055] Note that after the molding step, a sealing material may be applied to the inner peripheral press-fitting portion 53a or the inner peripheral portion to be press-fitted 53b, and then an assembling step may be performed so that the sealing material is interposed in the inner peripheral sealing portion 53. Similarly, after the molding step, a sealing material may be applied to the outer peripheral press-fitting portion 54a or the outer peripheral portion to be press-fitted 54b, and then an assembling step may be performed so that the sealing material is interposed in the outer peripheral sealing portion 54.

[0056] Next, the operation and effects of the compressor housing 1 for a turbocharger according to the present embodiment will be described in detail. According to the compressor housing 1 for a turbocharger of the present embodiment, the diffuser passage side wall surface 58 of the refrigerant flow path 5 extends parallel to the radial direction X, and the average size S in the radial direction X in the space 50 forming the refrigerant flow path 5 is larger than the average size T in the axial direction Y in the space 50. Thereby, by securing a wide diffuser passage side wall surface 58 of the refrigerant flow path 5, the heat receiving area from the diffuser surface 34 to the refrigerant flowing through the refrigerant flow path 5 can be increased, and by reducing the cross-sectional area of the refrigerant flow path 5, the flow velocity of the refrigerant in the refrigerant flow path 5 can be increased. As a result, the cooling effect of the diffuser surface 34 is enhanced, and the effect of preventing the deposition of deposits is improved. Further, since the compressor housing 1 for a turbocharger is formed by dividing into a plurality of pieces, it is not necessary to use a core when casting, so that the core removal work and the inspection work for core residues are not required, and the productivity is improved.

[0057] Further, in the first embodiment, the average size S in the radial direction X in the space 50 forming the refrigerant flow path 5 and the average size T in the axial direction Y in the space 50 satisfy the relationship of 1 < S / T ≤ 9. Thereby, since the cross-sectional area of the refrigerant flow path 5 does not become too small, the flow rate of the refrigerant in the refrigerant flow path 5 can be maintained, and the cooling effect can be further improved.

[0058] Further, in the first embodiment, the diffuser passage side wall surface 58 in the second flow path forming portion 52 extends in parallel to the radial direction X over the entire circumference. Thereby, since a wide diffuser passage side wall surface 58 can be secured, the cooling effect by the refrigerant flowing through the refrigerant flow path 5 can be further improved.

[0059] Further, in the first embodiment, the second flow path forming portion 52 in the shroud piece 3 as the second piece is formed in a concave shape, and the diffuser passage side wall surface 58 of the refrigerant flow path 5 is formed by the bottom surface of the second flow path forming portion 52 having a concave shape. Thereby, since the diffuser passage side wall surface 58 of the refrigerant flow path 5 can be formed at a position closer to the diffuser surface 34, the cooling effect by the refrigerant flowing through the refrigerant flow path 5 can be further improved.

[0060] Further, in the first embodiment, the inner peripheral seal portion 53 is formed by press-fitting an inner peripheral press-fitting portion 53a formed in the scroll piece 2 as the first piece into the inner peripheral side of an inner peripheral press-fitted portion 53b formed in the shroud piece 3 as the second piece, and the outer peripheral seal portion 54 is formed by press-fitting an outer peripheral press-fitting portion 54a formed in the scroll piece 2 as the first piece into the inner peripheral side of an outer peripheral press-fitted portion 54b formed in the shroud piece 3 as the second piece. Thereby, the inner peripheral seal portion 53 and the outer peripheral seal portion 54 can maintain the sealing property even if the thicknesses of the inner peripheral press-fitted portion 53b and the outer peripheral press-fitted portion 54b are relatively thin, so that the formation region of the refrigerant flow path 5 can be increased in the radial direction X. As a result, the diffuser passage side wall surface 58 of the refrigerant flow path 5 can be widened, and the cooling effect by the refrigerant flowing through the refrigerant flow path 5 can be further improved.

[0061] As described above, according to the first embodiment, the cooling effect of the diffuser surface 34 is enhanced to improve the deposit prevention effect, and the turbocharger compressor housing 1 with improved productivity can be provided.

[0062] The present invention is not limited to the above-described embodiment and modification examples, and can be applied to various embodiments and modification examples without departing from the gist thereof.

Explanation of Reference Numerals

[0063] 1 Compressor housing for turbocharger 2 Scroll piece 3 Shroud piece 30 Diffuser section 5 Refrigerant flow path 50 Space 51 First flow path forming section 52 Second flow path forming section 53 Inner peripheral seal section 53a Inner peripheral press-fitting section 53b Inner peripheral press-fitted section 54 Outer peripheral seal section 54a Outer peripheral press-fitting section 54b Outer peripheral press-fitted section 55 Intake port side wall surface 56 Outer peripheral side wall surface 57 Inner peripheral side wall surface 58 Diffuser passage side wall surface

Claims

1. A compressor housing for a turbocharger configured to house a compressor impeller and be attached to a center housing, comprising: An intake port forming portion that forms an intake port for sucking air toward the compressor impeller; A shroud portion that surrounds the compressor impeller in the circumferential direction and has a shroud surface facing the compressor impeller; A diffuser portion formed in the circumferential direction on the outer peripheral side of the compressor impeller to form a diffuser passage for compressing the air discharged from the compressor impeller; A scroll chamber forming portion that forms a scroll chamber for guiding the compressed air passing through the diffuser passage to the outside; A refrigerant flow path formed in the circumferential direction along the diffuser portion and for circulating a refrigerant that cools the diffuser portion; And having: The compressor housing for the turbocharger is divided into a plurality of pieces including a first piece having at least a part of the scroll chamber forming portion and the intake port forming portion, and a second piece having at least a part of the scroll chamber forming portion, a part of the shroud portion, and the diffuser portion. The refrigerant flow path is formed as an annular space partitioned by a first flow path forming portion including a side wall surface of the intake port of the refrigerant flow path formed in the first piece and a second flow path forming portion including a side wall surface of the diffuser passage of the refrigerant flow path formed at a position facing the first flow path forming portion in the second piece. The first flow path forming portion and the second flow path forming portion are fitted to each other at an inner peripheral seal portion that seals the inner peripheral side of the refrigerant flow path and an outer peripheral seal portion that seals the outer peripheral side of the refrigerant flow path. In a cross-section including the rotation axis of the compressor impeller, the side wall surface of the diffuser passage of the refrigerant flow path extends parallel to the radial direction, and the average radial size S of the space forming the refrigerant flow path is larger than the average axial size T of the space. A compressor housing for a turbocharger.

2. The compressor housing for a turbocharger according to claim 1, wherein the average radial size S and the average axial size T of the space forming the refrigerant flow path satisfy the relationship 1 < S / T ≤ 9.

3. The side wall surface of the diffuser passage in the second flow path forming portion extends in parallel in the radial direction over the entire circumference. The compressor housing for a turbocharger according to claim 1 or 2.

4. The second flow path forming portion in the second piece is formed in a concave shape. The side wall surface of the diffuser passage of the refrigerant flow path is formed by the bottom surface of the second flow path forming portion having the concave shape. The compressor housing for a turbocharger according to claim 1 or 2.

5. The inner peripheral seal portion is formed by press-fitting an inner peripheral press-fitting portion formed in the first piece into the inner peripheral side of an inner peripheral press-fitted portion formed in the second piece. The outer peripheral seal portion is formed by press-fitting an outer peripheral press-fitting portion formed in the first piece into the inner peripheral side of an outer peripheral press-fitted portion formed in the second piece. The compressor housing for a turbocharger according to claim 1 or 2.

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