Patent Application
20200263701
The present application claims priority under 35 U.S.C. § 119 to Japanese Application No. 2019-026413, filed on Feb. 18, 2019, entitled “COMPRESSOR HOUSING FOR TURBOCHARGER AND METHOD FOR MANUFACTURING THE SAME”. The contents of this application are incorporated herein by reference in their entirety.
The present disclosure relates to a compressor housing for a turbocharger and a method for manufacturing the same.
A turbocharger to be mounted on an internal combustion engine of an automobile, etc. includes a compressor impeller and a turbine impeller, which are housed in a housing. The compressor impeller is disposed in an air flow path that is formed inside the housing. The air flow path is provided with an intake port for sucking in air toward the compressor impeller, a diffuser passage through which compressed air discharged from the compressor impeller passes, and a discharge scroll chamber into which the compressed air passing through the diffuser passage flows. The discharge scroll chamber discharges the compressed air into the internal combustion engine side.
Some internal combustion engines for an automobile, etc. are provided with a positive crankcase ventilation system (hereinafter referred to as PCV) for purifying the inside of a crankcase and/or a head cover by reflowing blowby gas that has generated in the crankcase. In such a configuration, oil (oil mist) contained in the blowby gas may flow out from the PCV into an intake passage that is located upstream of the compressor in the turbocharger under some circumstances.
At that time, if air pressure at an outlet port of the compressor is high, air temperature there is made high, so that the oil flowing out from the PCV is concentrated and thickened by evaporation to have high viscosity. In some cases, the oil is accumulated as deposit on, for example, the diffuser surface of a compressor housing for a turbocharger and/or the surface of a bearing housing which opposes the diffuser surface. And, there is a risk that the deposit thus accumulated may narrow the diffuser passage to thereby cause reduction in performance of the turbocharger and reduction in output of the internal combustion engine.
In the past, the air temperature at the outlet port of the compressor was controlled to some extent to prevent such deposit accumulation in the diffuser passage as described above. As a result, a turbocharger was not able to satisfactorily exhibit its performance, and the output of an internal combustion engine was not satisfactorily raised.
Patent Document 1 discloses a configuration to prevent deposit accumulation in a diffuser passage, in which a refrigerant flow path is provided inside a compressor housing for a turbocharger to allow a refrigerant to pass therethrough, thereby inhibiting an increase in the temperature of compressed air passing through an air flow path inside the housing. In the configuration disclosed in Patent Document 1, the compressor housing for a turbocharger is composed of a first piece, a second piece, and a third piece, and these components are assembled to one another to define the refrigerant flow path.
Patent Document 1
However, in order to keep liquid-tightness of the refrigerant flow path, the configuration disclosed in Patent Document 1 needs to form a holding portion for holding an O-ring serving as a sealing member between the first piece and the second piece and to fit the sealing member into the holding portion, and in addition, to hold the sealing member by the first piece and the second piece. Thus, parts count is indispensably increased, which causes increase in manufacturing cost and reduction in assembling workability.
Further, in the configuration disclosed in Patent Document 1, each piece is formed in a shape having no undercut part in view of mold releasing in order to mold the piece by die casting. The cross-sectional shape of the scroll chamber is far different from a circle form accordingly, and such a shape causes reduction in compression efficiency of supplied air.
As a method to form the refrigerant flow path in the compressor housing for a turbocharger, it is conceivable to use gravity casting with a sand core. In this method, high flexibility in shape can be expected to thereby meet complicated shapes. On the other hand, this method requires long casting cycle, and needs a sand shakeout operation for removing the sand core and an inspection work for checking remaining casting sand. Therefore, the number of manufacturing processes is increased, and the productivity is reduced accordingly.
Furthermore, according to the configuration of Patent Document 1, the refrigerant flow path thus provided serves to prevent deposit accumulation, so that the flow rate of the compressor impeller can be increased to thereby increase the maximum output of an engine owing to the high supercharging thus attained. Meanwhile, the increased flow rate of the compressor impeller and the unfavorable cross sectional shape of the scroll chamber cause reduction of low-speed torque in an engine.
The present disclosure has been made in view of this background, and is directed to a compressor housing for a turbocharger in which sticking of deposit is prevented, satisfactory assembling workability is achieved, molding can be easily made by die casting, so that the performance on the high airflow-rate side is improved while the performance on the low airflow-rate side is maintained at low cost.
One embodiment of the present disclosure provides a compressor housing for a turbocharger configured to house a compressor impeller, the compressor housing including:
an intake port formation part that defines an intake port configured to suck in air toward the compressor impeller;
a shroud part that surrounds the compressor impeller in a circumferential direction and has a shroud surface facing the compressor impeller;
a diffuser part that is formed on an outer circumferential side of the compressor impeller in the circumferential direction and forms a diffuser passage configured to allow compressed air discharged from the compressor impeller to pass therethrough;
a scroll chamber formation part that forms a scroll chamber configured to guide the compressed air passing through the diffuser passage to outside;
a refrigerant flow path that is formed along the diffuser part in the circumferential direction, and allows a refrigerant for cooling the diffuser part to pass therethrough; and
a recirculation part configured to recirculate part of the air which has been sucked in from the intake port and reached the shroud part, to an upstream of the compressor impeller,
wherein the compressor housing is dividably composed of a scroll piece including at least part of the intake port formation part and at least part of the scroll chamber formation part, and a shroud piece including at least part of the scroll chamber formation part, the diffuser part, and the shroud part, and being press-fitted into an inner side of the scroll piece in a shaft direction,
wherein the refrigerant flow path is formed as an annular space that is defined by a first flow-path formation part of the scroll piece and a second flow-path formation part of the shroud piece, the first flow-path formation part and the second flow-path formation part being formed respectively at each opposing part of the scroll piece and the shroud piece which oppose each other,
wherein the first flow-path formation part and the second flow-path formation part are fitted with each other at an inner circumferential seal part configured to seal the refrigerant flow path on the inner circumferential side of the refrigerant flow path and at an outer circumferential seal part configured to seal the refrigerant flow path on the outer circumferential side of the refrigerant flow path,
wherein the inner circumferential seal part is formed by press-fitting a first press-fitting portion of the shroud piece into a first press-fitted portion of the scroll piece,
wherein the outer circumferential seal part is formed by press-fitting a second press-fitting portion of the shroud piece into a second press-fitted portion of the scroll piece, and
wherein the recirculation part includes: a recirculation chamber as a space that is defined by a first recirculation chamber formation part of the scroll piece and a second recirculation chamber formation part of the shroud piece, the first recirculation chamber formation part and the second recirculation chamber formation part being formed respectively at each opposing part of the scroll piece and the shroud piece which oppose each other; a communication part that is open at the shroud surface and is communicated with the recirculation chamber; and a blowout part that is open at the scroll piece, or in an upstream position of the compressor impeller of the shroud piece, and is communicated with the recirculation chamber.
According to the compressor housing for a turbocharger as the one embodiment of the present disclosure, the compressor housing for a turbocharger is dividably formed, and the refrigerant flow path is defined by the first flow-path formation part and the second flow-path formation part. The first flow-path formation part and the second flow-path formation part are formed respectively at each opposing part of the scroll piece and the shroud piece which oppose each other. The refrigerant flow path is sealed at an inner circumferential seal part on the inner circumferential side of the refrigerant flow path and at an outer circumferential seal part on the outer circumferential side of the refrigerant flow path. The inner circumferential seal part is formed by press-fitting the first press-fitting portion of the shroud piece into the first press-fitted portion of the scroll piece, and the outer circumferential seal part is formed by press-fitting the second press-fitting portion of the shroud piece into a second press-fitted portion of the scroll piece. The recirculation chamber of the recirculation part is formed of a space that is defined by a first recirculation chamber formation part of the scroll piece and a second recirculation chamber formation part of the shroud piece. The first recirculation chamber formation part and the second recirculation chamber formation part are formed respectively at each opposing part of the scroll piece and the shroud piece which oppose each other. Such configurations make it possible to seal the refrigerant flow path on the inner circumferential side of the refrigerant flow path and on the outer circumferential side of the refrigerant flow path while forming the recirculation part only by press-fitting the shroud piece into the scroll piece to assemble the both. Consequently, it becomes unnecessary to interpose an O-ring between the first flow-path formation part and the second flow-path formation part, and the assembling workability is satisfactory. Further, because the O-ring itself is not necessary, reduction of the parts count can be achieved. In addition, the refrigerant flow path provided in the compressor housing for a turbocharger makes it possible to restrain deposit accumulation in the diffuser passage to thereby achieve high supercharging on the high airflow-rate side of the compressor (at high speed rotation side of an engine) and to increase the maximum output of the engine.
In addition, the recirculation part can recirculate part of the air that has reached the shroud part, to an upstream side of the compressor impeller, and constitutes a so-called casing treatment. Accordingly, even when the flow rate of the compressor impeller is made largely increased in response to high supercharging, the operation range on the low airflow-rate side can be maintained and reduction of the low-speed torque can be prevented. In other words, the compressor housing for a turbocharger makes it possible both to maintain the low-speed torque, which is owing to the fact that the operation range on the low airflow-rate side is maintained by the recirculation part, and to increase the maximum output, which is owing to the fact that the refrigerant flow path brings about high supercharging.
Further, the compressor housing for a turbocharger is dividably formed and includes the scroll piece and the shroud piece. The scroll chamber is formed by assembling at least both the pieces to each other. Such a configuration makes it possible to form the scroll chamber with a circular cross section while forming the scroll chamber formation part in a shape having no undercut part, which enables mold releasing. As a result, the scroll chamber can be more easily formed by die casting while the compression efficiency for the supplied air can be improved.
As mentioned above, the one embodiment of the present disclosure can provide a compressor housing for a turbocharger in which sticking of deposit is prevented, satisfactory assembling workability is achieved, molding can be easily made by die casting, and high supercharging is achieved at low cost.
It is noted that the reference numerals throughout the specification correspond with the specific means which are described in the embodiments described later, and are not to limit the technical scope of the present disclosure.
“Circumferential direction” in the present specification means the rotation direction of a compressor impeller, “shaft direction” means the direction of the rotation shaft of the compressor impeller, “radial direction” means the radius direction of an imaginary circle centered on the rotation shaft of the compressor impeller, and “outside in the radial direction” and “radially outside of” are defined to be in the direction straightly extending from the center of the imaginary circle to the circumference of the circle.
The scroll piece and the shroud piece preferably have in common a contact portion configured to perform positioning at press-fitting by contacting the scroll piece and the shroud piece in a state of opposing in the shaft direction. In this case, the contact portion performs positioning of the scroll piece and the shroud piece in the shaft direction Y serving as a press-fitting direction, whereby the assembling precision of the scroll piece and the shroud piece can be improved.
A method for manufacturing the compressor housing for a turbocharger preferably includes molding the scroll piece and the shroud piece by die-casting; forming the first and second press-fitted portions in the scroll piece, and the first and second press-fitting portions and the communication part in the shroud piece, respectively by machining; and assembling the shroud piece into the scroll piece while forming the refrigerant flow path and the recirculation part by forming the inner circumferential seal part and the outer circumferential seal part, the inner circumferential seal part being formed by press-fitting the first press-fitting portion into the first press-fitted portion, and the outer circumferential seal part being formed by press-fitting the second press-fitting portion into the second press-fitted portion. In this case, only by molding the scroll piece and the shroud piece by die-casting, forming the first and second press-fitted portions in the scroll piece, and the first and second press-fitting portions and the communication part in the shroud piece, respectively by machining, thereafter by press-fitting the shroud piece into the scroll piece to assemble the both, the refrigerant flow path can be sealed on the inner circumferential side of the refrigerant flow path and on the outer circumferential side of the refrigerant flow path while forming recirculation part. Consequently, it becomes unnecessary to interpose an O-ring between the first flow-path formation part and the second flow-path formation part, and the assembling workability is made satisfactory. Further, because the O-ring itself is not necessary, reduction of the parts count can be achieved.
Hereinafter, embodiments of the aforementioned compressor housing for a turbocharger will be described with reference to
As shown in
The intake port formation part 10 forms an intake port 11 configured to suck in air toward the compressor impeller 13.
The shroud part 20 surrounds the compressor impeller 13 in the circumferential direction and has a shroud surface 21 facing the compressor impeller 13.
The diffuser part 30 is formed on the outer peripheral side of the compressor impeller 13 in the circumferential direction, and forms a diffuser passage 15 that allows compressed air discharged from the compressor impeller 13 to pass therethrough.
The scroll chamber formation part 120 forms a scroll chamber 12 for guiding the compressed air having passed through the diffuser passage 15 to the outside.
The refrigerant flow path 5 is formed along the diffuser part 30 in the circumferential direction, and allows a refrigerant for cooling the diffuser part 30 to pass therethrough.
The recirculation part 6 is configured to recirculate part of the air, which has been sucked in from the intake port 11 and reached the shroud part 20, to the upstream of the compressor impeller 13.
The compressor housing 1 for a turbocharger is dividably composed of a scroll piece 2 including at least part of the intake port formation part 10 and at least part of the scroll chamber formation part 120, and a shroud piece 3 including at least part of the scroll chamber formation part 120, the diffuser part 30, and the shroud part 20, and being inserted in the inner side of the scroll piece 2.
As shown in
The first flow-path formation part 51 and the second flow-path formation part 52 are fitted with each other at an inner circumferential seal part 53 configured to seal the refrigerant flow path 5 on the inner circumferential side of the refrigerant flow path 5 and at an outer circumferential seal part 54 configured to seal the refrigerant flow path 5 on the outer circumferential side of the refrigerant flow path 5.
The inner circumferential seal part 53 is formed by press-fitting a first press-fitting portion 53b of the shroud piece 3 into a first press-fitted portion 53a of the scroll piece 2.
The outer circumferential seal part 54 is formed by press-fitting a second press-fitting portion 54b of the shroud piece 3 into a second press-fitted portion 54a of the scroll piece 2.
Further, as shown in
Hereinafter, the compressor housing 1 for a turbocharger according to the present embodiment will be described in detail.
As shown in
The scroll piece 2, as shown in
As shown in
As shown in
As shown in
One or both of the inner circumferential seal part 53 and the outer circumferential seal part 54 may be preferably provided with a sealing material. Although the kinds of the seal material are not specifically limited, quickly dryable ones are preferable. For example, sealing materials to be used as a liquid gasket can be used.
As shown in
As shown in
As shown in
On the other hand, the shroud piece 3 includes, as shown in
As shown in
As shown in
As shown in
The shroud piece 3 is fitted into the scroll piece 2 as shown in
The seal plate 40 includes, as shown in
Next, a method for manufacturing the compressor housing 1 for a turbocharger according to the present embodiment will be described.
The method for manufacturing the compressor housing 1 for a turbocharger includes a molding/forming step S1, and an assembling step S2. Firstly in the molding/forming step S1, the scroll piece 2 and the shroud piece 3 are separately prepared by die casting, as shown in
Subsequently in the assembling step S2, a shroud press-fit portion 31 of the shroud piece 3 is press-fitted into the inside of the intake port formation part 10 of the scroll piece 2 in the direction as shown by an arrow P in
In this way, by press-fitting the shroud piece 3 into the scroll piece 2, the first press-fitting portion 53b of the shroud piece 3 is press-fitted into the first press-fitted portion 53a of the scroll piece 2 to form the inner circumferential seal part 53, and the second press-fitting portion 54b of the shroud piece 3 is press-fitted into the second press-fitted portion 54a of the scroll piece 2 to form the outer circumferential seal part 54. And thus, the first flow-path formation part 51 and the second flow-path formation part 52 are sealed in the refrigerant flow path 5. In the present embodiment, the shroud surface 21 is subjected to machining to thereby ensure the molding accuracy. In this way, the compressor housing 1 for a turbocharger as shown in
In the compressor housing 1 for a turbocharger, a refrigerant introduction tube and a refrigerant discharge tube, which are not shown in any figure, are connected respectively to the refrigerant feed part 58 and the refrigerant discharging part 59 each communicated with the refrigerant flow path 5 as shown in
It is noted that the sealing material may be provided at the inner circumferential seal part 53 by applying the sealing material to the first press-fitted portion 53a or the first press-fitting portion 53b after the molding/forming step S1, and then performing the assembling step S2. Similarly, the sealing material may be provided at the outer circumferential seal part 54 by applying the sealing material to the second press-fitted portion 54a or the second press-fitting portion 54b after the molding/forming step S1, and then performing the assembling step S2.
Hereinafter, operational 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 compressor housing 1 for a turbocharger is dividably formed, and the refrigerant flow path 5 is defined by the first flow-path formation part 51 of the scroll piece 2 and the second flow-path formation part 52 of the shroud piece 3, which are formed respectively at each opposing part of the scroll piece 2 and the shroud piece 3 which oppose each other. The inner circumferential seal part 53 and the outer circumferential seal part 54 seal the refrigerant flow path 5 respectively on the inner circumference side and on the outer circumference side. The inner circumferential seal part 53 is formed by press-fitting the first press-fitting portion 53b of the shroud piece 3 into the first press-fitted portion 53a of the scroll piece 2, and the outer circumferential seal part 54 is formed by press-fitting the second press-fitting portion 54b of the shroud piece 3 into the second press-fitted portion 54a of the scroll piece 2. The recirculation chamber 60 of the recirculation part 6 is formed of a space that is defined by the first recirculation chamber formation part 61 of the scroll piece 2 and the second recirculation chamber formation part 62 of the shroud piece 3, the first recirculation chamber formation part 61 and the second recirculation chamber formation part 62 being formed respectively at each opposing part of the scroll piece 2 and the shroud piece 3 which oppose each other. Such a configuration makes it possible to seal the refrigerant flow path 5 on the inner circumferential side of the refrigerant flow path 5 and on the outer circumferential side of the refrigerant flow path 5 while forming the recirculation part 6, only by press-fitting the shroud piece 3 into the scroll piece 2 to assemble the both. Consequently, it becomes unnecessary to interpose an O-ring between the first flow-path formation part 51 and the second flow-path formation part 52, and the assembling workability is made satisfactory. Further, because the O-ring itself is not necessary, reduction of the parts count can be achieved. Thus, the refrigerant flow path 5 provided in the compressor housing 1 for a turbocharger makes it possible to restrain deposit accumulation in the diffuser passage 15 to thereby achieve high supercharging on high speed rotation side of an engine and to increase the maximum output of the engine.
Moreover, the compressor housing 1 for a turbocharger is provided with the recirculation part 6 that can recirculate part of the air, which has reached the shroud part 20, to the upstream side of the compressor impeller 13. The recirculation part 6 constitutes a so-called casing treatment, therefore even when the flow rate of the compressor impeller 13 is made largely increased in response to high supercharging, the operation range on the low airflow-rate side can be maintained and reduction of the low-speed torque can be prevented. In other words, the compressor housing 1 for a turbocharger according to the present embodiment makes it possible both to maintain the low-speed torque, which is owing to the fact that the operation range on the low airflow-rate side is maintained by the recirculation part 6, and to increase the maximum output, which is owing to the fact that the refrigerant flow path 5 brings about high supercharging.
Furthermore, the compressor housing 1 for a turbocharger is dividably formed and includes the scroll piece 2 and the shroud piece 3. The scroll chamber 12 is formed by assembling at least both the pieces to each other. Such a configuration makes it possible to form the scroll chamber 12 with a circular cross section while forming the scroll chamber formation part 120 in a shape having no undercut part, which enables mold releasing. As a result, the scroll chamber 12 can be more easily formed by die casting while the compression efficiency for the supplied air can be improved.
In addition, the refrigerant flow path 5 in the compressor housing 1 for a turbocharger according to the present embodiment is easily applicable to a conventional compressor housing for a turbocharger because it requires no significant change in the basic configuration of a scroll piece and a shroud piece from the conventional one.
In the present embodiment, the scroll piece 2 includes the refrigerant feed part 58 formed of a penetration hole that communicates with the refrigerant flow path 5 to feed a refrigerant to the refrigerant flow path 5, and the refrigerant discharging part 59 formed of a penetration hole that communicates with the refrigerant flow path 5 to discharge the refrigerant from the refrigerant flow path 5. Such a configuration makes it possible to easily form the refrigerant feed part 58 and the refrigerant discharging part 59 and to surely flow the refrigerant through the refrigerant flow path 5.
In the present embodiment, at least one of the inner circumferential seal part 53 and the outer circumferential seal part 54 may be provided with a sealing material between the scroll piece 2 and the shroud piece 3 to seal a gap therebetween. Such a configuration makes it possible to enhance sealability at least one of the inner circumferential seal part 53 and the outer circumferential seal part 54 thereby preventing leakage of the refrigerant from the refrigerant flow path 5 to increase the reliability.
In the present embodiment, the scroll piece 2 and the shroud piece 3 have in common a contact portion 56 configured to perform positioning at press-fitting by contacting the scroll piece 2 and the shroud piece 3 in a state of opposing in the shaft direction Y. In such a configuration, the contact portion 56 performs positioning of the scroll piece 2 and the shroud piece 3 in the shaft direction Y serving as a press-fitting direction, whereby the assembling precision of the scroll piece 2 and the shroud piece 3 can be improved.
The method for manufacturing the compressor housing 1 for a turbocharger according to the present embodiment includes the molding/forming step S1 of molding the scroll piece 2 and the shroud piece 3 by die-casting and forming the first press-fitted portion 53a and the second press-fitted portion 54a in the scroll piece 2, and the first press-fitting portion 53b, the second press-fitting portion 54b, and the communication part in the shroud piece 3, respectively by machining; and the assembling step S2 of assembling the shroud piece 3 to the scroll piece 2, while forming the refrigerant flow path 5 composed of the annular space 50, and the recirculation part 6 by forming the inner circumferential seal part 53 and the outer circumferential seal part 54. The inner circumferential seal part 53 is formed by press-fitting the first press-fitting portion 53b into the first press-fitted portion 53a, and the outer circumferential seal part 54 is formed by press-fitting the second press-fitting portion 54b into the second press-fitted portion 54a. Such a configuration makes it possible to seal the refrigerant flow path 5 on the inner circumferential side of the refrigerant flow path 5 and on the outer circumferential side of the refrigerant flow path 5 while forming the recirculation part 6 only by press-fitting the shroud piece 3 into the scroll piece 2 to assemble both in the assembling step S2 after molding the scroll piece 2 and the shroud piece 3 by die-casting and then forming the first press-fitted portion 53a and the second press-fitted portion 54a in the scroll piece 2, and the first press-fitting portion 53b, the second press-fitting portion 54b and the communication part 63 in the shroud piece 3, respectively by machining in the molding/forming step S1. Consequently, it becomes unnecessary to interpose an O-ring between the first flow-path formation part 51 and the second flow-path formation part 52, and the assembling workability is made satisfactory. Further, because the O-ring itself is not necessary, reduction of the parts count can be achieved.
In the present embodiment, the compressor housing 1 for a turbocharger is of a two-piece structure that is composed of the scroll piece 2 and the shroud piece 3. The compressor housing 1 may be of a three-piece structure that is composed of the scroll piece 2, the shroud piece 3, and an annular outer circumference piece 4 as in Modification 1 shown in
Hereinafter, a method for manufacturing the compressor housing 1 for a turbocharger according to Modification 1 will be described. First, in the molding/forming step S1, the scroll piece 2 is molded by die-casting in a similar way to that in Embodiment 1 as shown in
The compressor housing 1 for a turbocharger according to Modification 1 also exhibits the operational effects equivalent to those in Embodiment 1. An interference of the press-fit part 42 into which the annular outer circumference piece 4 is press-fitted is preferably smaller than those of the inner circumferential seal part 53 and the outer circumferential seal part 54. In this case, the integrated piece 3a can be easily press-fitted into the scroll piece 2. In addition, misalignment between the press-fit part of the shroud piece 3 (the inner circumferential seal part 53 and the outer circumferential seal part 54) and the press-fit part 42 of the annular outer circumference piece 4 can be absorbed.
In the compressor housing 1 for a turbocharger according to Modification 1, a part of the integrated piece 3a for constituting the annular outer circumference piece 4 is not brought into contact with the scroll piece 2 in the shaft direction in the assembling step S2 so as to form a gap B, as shown in
It is noted that the refrigerant flow path 5 is formed by die-casting in Embodiment 1, but instead, as in Modification 2 shown in
The present disclosure is not limited to the aforementioned embodiment and modifications, and can be applied to various embodiments and modifications within a range that does not deviate from the gist of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-026413 | Feb 2019 | JP | national |
