JP2008106667A - Turbine housing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a turbine housing capable of preventing change of a tip clearance due to thermal deformation or the like as much as possible, even if wall thickness of a scroll body is thinned. <P>SOLUTION: The turbine housing for a turbocharger with a variable nozzle vane 20 is provided with the scroll body 1 defining an annular tunnel shape exhaust gas passage 11, a bearing housing side flange 3 provided on a back surface side of the scroll body, a nozzle wall surface flange 5 provided at a central area of the scroll body and near an exhaust gas outlet 12, and a connecting ring 8 for connecting both of flanges 3, 5. The connecting ring 8 includes a plurality of ventilation slits 3 extending in a circumference direction and a plurality of column shape connecting parts 81 existing between the plurality of the ventilation slits S. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an exhaust turbine housing (so-called turbine housing) in a turbocharger. In particular, it relates to a turbine housing for a turbocharger with nozzle vanes.

  Conventionally, the turbine housing is generally made of a casting, but the casting turbine housing has various drawbacks. For example, A: Casting failure is likely to occur in turbine housings that are generally complex in shape, B: Casting failure is likely to occur when high heat resistant materials that are generally poorly castable are used, C: Cast products are heavy There were drawbacks such as being heavy and disadvantageous for in-vehicle use. For this reason, for example, the turbine housing is divided into two parts, and each divided casing is made of a metal plate press product, thereby enabling to cope with a complicated shape, use a high heat resistant material, and reduce the weight of the housing body. This has also been proposed (see Patent Document 1). Initially, the casting of the turbine housing was proposed in order to eliminate the drawbacks of the cast product, but in recent years, from the viewpoint of early activation of the exhaust gas purification catalyst at the low temperature start of the automobile engine, A turbine housing, which is a kind of exhaust system component, is also required to have a low heat capacity by thinning.

  By the way, in the turbocharger field, a variable nozzle vane is disposed between an annular exhaust gas passage defined by the scroll body of the turbine housing and the exhaust turbine, and the opening of the variable nozzle vane (specifically, There is known a turbocharger with a variable nozzle vane that can adjust the flow rate or flow rate of exhaust gas acting on the exhaust turbine by adjusting the inclination angle of each vane according to the operating condition of the engine (for example, Patent Document 2). reference).

JP-A-55-37508 Japanese Patent Laid-Open No. 1-267303 (Conventional Technology)

  As described above, the turbine housing is in the direction of thinning. On the other hand, the thinning of the housing causes a decrease in mechanical rigidity. For this reason, the turbine housing itself undergoes thermal deformation (or deformation due to the influence of thermal deformation of peripheral components) during operation of the turbocharger. As a result, the clearance between the inner peripheral portion of the turbine housing and the outer peripheral portion of the exhaust turbine (“ This may cause a problem that the “chip clearance” changes) and adversely affects the supercharging performance. In particular, in a turbine housing for a turbocharger with nozzle vanes, the change in the tip clearance secured between the nozzle wall flange provided in the central area of the housing for positioning the nozzle vanes and the exhaust turbine is critical to the supercharging performance. affect.

  An object of the present invention is to provide a turbine housing capable of preventing changes in tip clearance due to thermal deformation or the like as much as possible even when the scroll body is thinned.

  The inventor of the present application has completed the present invention based on the following knowledge and idea regarding the turbocharger with nozzle vanes. That is, in the turbocharger with nozzle vanes, the gas flow in the turbine housing is dominated by the gas flow control by the nozzle vane rather than the cross-sectional area of the annular tunnel-shaped exhaust gas passage defined by the scroll body, and therefore the heat of the exhaust gas. Even if the scroll main body is somewhat thermally deformed, the supercharging performance should not be affected by that. However, in a turbocharger with a nozzle vane, a bearing housing side flange as a joint for connecting the turbine housing to a bearing housing that rotatably supports the exhaust turbine, and a nozzle wall surface for positioning the nozzle vane in the thrust direction The positional relationship or dimensional relationship between the flanges determines the tip clearance that has a significant effect on the supercharging performance. In addition, in the conventional turbine housing, the bearing housing side flange and the nozzle wall flange are connected via the scroll body (only), so that the thermal deformation of the scroll body is caused by the relative relationship between the bearing housing side flange and the nozzle wall flange. It was a factor that disturbed the arrangement. For this reason, with the thermal deformation etc. of the scroll body, the tip clearance is changed and the supercharging performance is lowered. Therefore, in the present invention, even if the scroll main body (or peripheral parts) is thermally deformed, the invention is devised so that the arrangement relationship between the bearing housing side flange and the nozzle wall surface flange is maintained as much as possible.

  The invention of claim 1 is a turbine housing for a turbocharger with a nozzle vane, wherein a scroll main body defining an annular tunnel-shaped exhaust gas passage, an exhaust gas inlet provided on a side portion of the scroll main body, Provided on the back side of the scroll body as a joint for connecting the turbine housing to an exhaust gas outlet provided in the center of the front side of the scroll body and a bearing housing that rotatably supports the exhaust turbine. A bearing housing side flange, a nozzle wall flange provided in a central region of the scroll body and in the vicinity of the exhaust gas outlet as a restricting portion for positioning the nozzle vane in the thrust direction with respect to the scroll body, and the bearing Housing side flange and nozzle wall flange A turbine housing, characterized in that it comprises a plurality of columnar connecting portion that interconnects the Nji.

  According to the first aspect, the mechanical rigidity and the dimensional stability are enhanced by connecting the bearing housing side flange and the nozzle wall surface flange with the plurality of columnar connecting portions. For this reason, even if the scroll body of the turbine housing and / or peripheral components of the turbine housing are thermally deformed by the heat of the exhaust gas, the bearing housing side flange and the nozzle wall flange interconnected by the columnar connecting portions are not affected by the heat deformation. Not much affected by That is, the relative arrangement relationship (or dimensional relationship) between the bearing housing side flange and the nozzle wall surface flange, which determines the tip clearance between the turbine housing and the exhaust turbine incorporated in the housing, hardly changes. Thus, since the change of the tip clearance due to thermal deformation or the like can be prevented as much as possible, the scroll main body can be thinned (and hence reduced in heat capacity and weight) without deteriorating the supercharging performance.

  According to a second aspect of the present invention, in the turbine housing according to the first aspect, the bearing housing side flange, the nozzle wall surface flange, and the plurality of columnar connecting portions are formed as a single cast part integrally cast in advance. (Refer to FIG. 9).

  According to the second aspect of the present invention, the bearing housing side flange, the nozzle wall surface flange, and the plurality of columnar connecting portions are formed as a single cast part integrally cast in advance. Therefore, the positional relationship between the bearing housing side flange and the nozzle wall surface flange is determined at the casting stage, and as a result, changes in the tip clearance due to thermal deformation or the like can be prevented as much as possible.

  The invention of claim 3 is a turbine housing for a turbocharger with a nozzle vane, wherein a scroll body defining an annular tunnel-like exhaust gas passage, an exhaust gas inlet provided on a side of the scroll body, Provided on the back side of the scroll body as a joint for connecting the turbine housing to an exhaust gas outlet provided in the center of the front side of the scroll body and a bearing housing that rotatably supports the exhaust turbine. A bearing housing side flange, a nozzle wall flange provided in a central region of the scroll body and in the vicinity of the exhaust gas outlet as a restricting portion for positioning the nozzle vane in the thrust direction with respect to the scroll body, and the bearing Housing side flange and nozzle wall flange And a plurality of ventilation slits extending in the circumferential direction, and a plurality of columnar coupling portions existing between the plurality of ventilation slits. A turbine housing.

  According to the third aspect, the mechanical rigidity and the dimensional stability are enhanced by connecting the bearing housing side flange and the nozzle wall surface flange with the connecting ring having a plurality of columnar connecting portions. For this reason, even if the scroll body of the turbine housing and / or peripheral components of the turbine housing are thermally deformed by the heat of the exhaust gas, the bearing housing side flange and the nozzle wall surface flange interconnected by the columnar connecting portion of the connecting ring are Not affected by the heat deformation. That is, the relative arrangement relationship (or dimensional relationship) between the bearing housing side flange and the nozzle wall surface flange, which determines the tip clearance between the turbine housing and the exhaust turbine incorporated in the housing, hardly changes. Thus, since the change of the tip clearance due to thermal deformation or the like can be prevented as much as possible, the scroll main body can be thinned (and hence reduced in heat capacity and weight) without deteriorating the supercharging performance. In addition, since a plurality of columnar connection parts are grouped into a single part called a connection ring, each columnar connection is made to both flanges by simply positioning the connection ring with respect to the bearing housing side flange and the nozzle wall flange. The connecting portions can be positioned at a time, and the assemblability of the plurality of columnar connecting portions with respect to the turbine housing can be improved.

  According to a fourth aspect of the present invention, in the turbine housing according to the third aspect, the connection ring further includes a front end side and a rear end side annular portion sandwiching a group of the plurality of ventilation slits, The annular portion at one end of the connecting ring is welded to the inner peripheral portion of the bearing housing side flange, and the annular portion at the other end of the connecting ring is welded to the outer peripheral portion of the nozzle wall surface flange.

  According to claim 4, the annular portion at one end of the connecting ring is welded to the inner peripheral portion of the flange on the bearing housing side, and the annular portion at the other end of the connecting ring is welded to the outer peripheral portion of the nozzle wall surface flange. The bearing housing side flange and the nozzle wall surface flange are interconnected.

  According to a fifth aspect of the present invention, the turbine housing according to the third aspect further comprises a ring-shaped bearing housing side flange cover for covering the part of the bearing housing side flange facing the scroll body over the entire circumference. The bearing housing side flange cover defines an annular heat insulating space between the flange cover and the bearing housing side flange, and defines the annular tunnel-shaped exhaust gas passage together with the scroll body. The bearing housing side flange cover and the connection ring are formed as a single component that is integrally molded in advance (see FIGS. 10 and 11).

  According to the fifth aspect, the number of parts can be reduced by forming the bearing housing side flange cover and the connecting ring as a single part integrally molded in advance. The bearing housing side flange is provided with a ring-shaped bearing housing side flange cover that covers the entire surface of the flange facing the scroll body. As a result, the bearing housing side flange cover and the bearing housing side flange are connected to each other. An annular heat insulating space is defined between them. For this reason, the high-temperature exhaust gas flowing through the annular tunnel-shaped exhaust gas passage while being guided by the flange cover does not directly contact the bearing housing side flange. Therefore, as a constituent material of the bearing housing side flange, a relatively inexpensive normal grade material can be used instead of an expensive high heat resistant material. In addition, since the temperature drop of the exhaust gas is suppressed by the high-temperature exhaust gas not directly hitting the bearing housing side flange having a relatively large heat capacity, early warm-up at the cold start of the engine and early exhaust gas purification catalyst Easy to activate.

  A sixth aspect of the present invention is the turbine housing according to any one of the first to fifth aspects, wherein each of the plurality of columnar connecting portions has a sector shape in cross section, and one of the columnar connecting portions is one of the columnar connecting portions. On the side surface, an inclined surface for guiding exhaust gas along one side of the sector cross section is 30 ° to a radial line connecting the turbo shaft center (C) and the inner edge (E1) of the inclined surface. It is characterized by having an inclination angle (θ) of 60 °.

  According to the sixth aspect, the inclined surface for guiding the exhaust gas formed on one side surface of each columnar connecting portion guides the flow of the exhaust gas. For this reason, it is possible to reduce the ventilation resistance of the radial exhaust gas passage from the annular tunnel-like exhaust gas passage of the scroll body to the nozzle vane via the space between the plurality of column-like connection portions (that is, the ventilation slits). A reduction in supercharging efficiency due to the provision can be prevented as much as possible.

  A seventh aspect of the present invention is the turbine housing according to any one of the first to sixth aspects, wherein the plurality of columnar connecting portions are for mounting nozzle vanes formed in the scroll body and / or the nozzle wall surface flange. It is provided respectively in the vicinity of the bolt hole.

  According to the seventh aspect, by providing each columnar coupling portion in the vicinity of the nozzle vane mounting bolt hole, even when the nozzle vane is mounted to the turbine housing using the mounting bolt, the columnar coupling portions (that is, the ventilation slits) are provided. ) Is relatively large. For this reason, it is possible to reduce the ventilation resistance of the radial exhaust gas passage from the annular tunnel-like exhaust gas passage of the scroll body to the nozzle vane via the space between the plurality of column-like connection portions (that is, the ventilation slits). A reduction in supercharging efficiency due to the provision can be prevented as much as possible.

  According to an eighth aspect of the present invention, in the turbine housing according to any one of the first to seventh aspects, the annular tunnel-shaped exhaust gas passage has a substantially constant cross-sectional area and cross-sectional shape over the entire circumference. It is characterized by being formed.

  According to the eighth aspect, it is possible to prevent the effect of the nozzle vane from being reduced due to a part of the annular tunnel-shaped exhaust gas passage being a bottleneck, and it is possible to improve the supercharging performance of the turbocharger. Later).

  According to the turbine housing for a turbocharger with nozzle vanes described in each claim, even when the scroll body is thinned, a change in the tip clearance due to thermal deformation or the like can be prevented as much as possible.

  Hereinafter, a turbine housing for a turbocharger with a variable nozzle vane according to an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIGS. 1 to 6, the turbine housing of this embodiment includes a scroll body 1, an outlet flange 2, a bearing housing side flange 3, an inlet flange 4, a nozzle wall surface flange 5, an annular reinforcing member 6, and a bearing housing side flange. A cover 7 and a connecting ring 8 are provided. A central axis C shown in each figure is a central axis common to the turbine housing and the scroll body 1 and also a turbo axis center in the turbocharger.

  As shown in FIGS. 1 to 3, the scroll body 1 has a substantially circular shape when viewed from the front, and a shape having high symmetry with respect to the central axis C in an arbitrary virtual cross section including the central axis C. It has become. As shown in FIG. 2, the scroll body 1 is positioned in the outer peripheral portion 1 a that has a substantially ring shape that swells like a donut, and in the central region of the scroll main body that is the radially inner region of the substantially ring-shaped outer peripheral portion 1 a. And an outlet hole peripheral wall 1b. A substantially ring-shaped outer peripheral portion 1a of the scroll body defines an annular tunnel-shaped exhaust gas passage 11 together with a bearing housing side flange cover 7 described later. Further, the outlet hole peripheral wall 1b of the scroll body extends in a bowl shape from the inner peripheral portion on the front side of the substantially ring-shaped outer peripheral portion 1a toward the central axis C (that is, in the radial direction of the turbine housing), It is substantially orthogonal to the central axis C. In addition, the scroll main body 1 is formed by hydroforming a sheet metal product obtained by pressing, for example, half-parts obtained by pressing a stainless steel plate, by overlapping bonding or butt bonding, or a hollow metal material (hydroforming). ) To be provided as an integrally molded product. The wall thickness of the scroll body 1 is preferably 0.8 to 2.5 mm.

  A circular outlet hole 12 is defined at the center of the outlet hole peripheral wall 1b of the scroll body 1 by the inner peripheral end of the outlet hole peripheral wall 1b. The outlet hole 12 is an exhaust gas outlet from the turbine housing that opens in front of the center of the scroll body 1. As shown in FIGS. 1A and 2, the outlet flange 2 is mounted on the front side of the outlet hole peripheral wall 1 b via an annular reinforcing member 6. More specifically, the annular reinforcing member 6 includes a cylindrical neck portion 6a extending along a central axis C having substantially the same diameter as the outlet hole 12, and a radially outward direction of the turbine housing from the proximal end portion of the cylindrical neck portion 6a. And at least a skirt-shaped skirt portion 6b. Then, by applying all-around welding (W1 and W2 in FIG. 2) with the collar-like skirt portion 6b joined to the front side of the outlet hole peripheral wall 1b of the scroll body, the annular reinforcing member 6 is attached to the scroll body 1 It is fixed by welding. Further, by performing a full circumference welding (W3) with the substantially ring-shaped outlet flange 2 fitted around the tip of the cylindrical neck portion 6a of the annular reinforcing member, the outlet to the scroll body 1 and the annular reinforcing member 6 is provided. The flange 2 is fixed by welding. The outlet flange 2 is a flange joint (joint portion) for connecting an external pipe (such as an elbow) on the downstream side of the turbine housing to the outlet hole 12 of the turbine housing.

  As shown in FIGS. 1C and 2, a substantially ring-shaped bearing housing side flange 3 (“center housing side flange”) is formed in the inner region of the rear side inner peripheral edge of the substantially ring-shaped outer peripheral portion 1 a of the scroll body 1. Also called). The flange 3 on the bearing housing side serves as a flange joint (joint part) for connecting and fixing the turbine housing to the bearing housing of the turbocharger, and the variable nozzle vane 20 and / or the exhaust turbine T (two-dot chain line in FIG. 2). As a restricting portion for positioning in the radial direction.

  As shown in FIG. 2, the bearing housing side flange 3 is provided with a bearing housing side flange cover 7 for covering the front side portion of the flange 3 facing the scroll body 1 over the entire circumference. The flange cover 7 generally has a ring shape, and the outer peripheral portion 7a of the flange cover 7 is formed in a short cylindrical ring shape with the central axis C as the center. As a constituent material of the flange cover 7, it is preferable to use a high heat resistant material (for example, ferritic stainless steel) equal to or higher than that of the scroll body 1. The thickness of the flange cover 7 is preferably 0.5 to 3.0 mm. And the outer peripheral part 7a of the flange cover 7 is welded to the outer peripheral surface of the annular outer peripheral part of the flange 3 on the bearing housing side (W4) so as to be welded to the outer peripheral part of the flange 3 It is fixed by welding. Further, the inner peripheral portion 7b of the flange cover 7 is welded and fixed to the annular front end portion of the flange 3 by being welded all around (W5) while being in contact with the annular front end portion of the bearing housing side flange 3. ing. As a result, an annular heat insulating space 10 is secured between the flange cover 7 and the bearing housing side flange 3.

  Furthermore, in this embodiment, the scroll body 1 and the flange cover 7 are connected by welding the inner peripheral edge (W4) of the rear surface side of the outer periphery 1a of the scroll body 1 to the outer periphery 7a of the flange cover 7. ing. As a result, the outer peripheral portion 1a of the scroll body and the flange cover 7 jointly define an annular tunnel-shaped exhaust gas passage 11. That is, the ring-shaped flange cover 7 covering the front side portion of the bearing housing side flange 3 facing the scroll body 1 over the entire circumference is an exhaust gas passage section for guiding the flow of exhaust gas along the exhaust gas passage 11. It plays a role as a wall and a role as a gas barrier that prevents high-temperature exhaust gas from directly contacting the bearing housing side flange 3.

  As shown in FIGS. 1 and 3, an inlet hole 13 as an exhaust gas inlet is formed in a side portion (upper end portion in FIG. 3) of the scroll main body 1, and the scroll main body 1 defining the inlet hole 13. An inlet flange 4 is provided outside the wall portion. The inlet flange 4 is a flange joint (joint part) for connecting an external pipe (not shown) upstream of the turbine housing to the inlet hole 13 of the turbine housing. Further, as shown in FIG. 3, a guide member 14 having a curved guide wall 14 a is provided in the exhaust gas passage 11 of the scroll body 1 and inside the inlet hole 13. The guide member 14 guides the exhaust gas that has entered the inlet hole 13 to one side of the annular tunnel-shaped exhaust gas passage 11 by the curved guide wall 14 a, thereby causing a one-way gas flow in the exhaust gas passage 11. Work to create. The guide member 14 includes an inlet position of the annular tunnel exhaust gas passage 11 defined in the scroll body 1 (starting point of the annular tunnel) and a winding end position of the annular tunnel exhaust gas passage 11 (end point of the annular tunnel). It is also a partition material that makes a border with).

  The annular tunnel-shaped exhaust gas passage 11 in the present embodiment is formed so that the cross-sectional area of the passage is substantially constant over the entire circumference and the cross-sectional shape of the passage is also substantially constant. That is, as shown in the graph of FIG. 7, the passage at any position over the entire circumference from the inlet position (0 ° position) of the annular tunnel-shaped exhaust gas passage 11 to the winding end position (360 ° position). The cross-sectional area is constant. On the other hand, in the comparative example (conventional type gradually changing cross-section turbine housing), the passage cross-sectional area tends to gradually decrease from the inlet position of the exhaust gas passage toward the end of winding.

  As shown in FIG. 2, a disk-shaped ring-shaped nozzle wall flange 5 is provided in the central region of the scroll body 1 and on the inner wall surface side of the outlet hole peripheral wall 1b. The nozzle wall surface flange 5 is integrated with the scroll body 1 by performing all-around welding (W1) while being joined to the outlet hole peripheral wall 1b. The nozzle wall surface flange 5 serves as a restricting portion for positioning the variable nozzle vane 20 (indicated by a two-dot chain line) in the thrust direction with respect to the scroll body 1 and a plurality of vanes 21 (indicated by broken lines) constituting the variable nozzle vane 20. It plays a role as an inter-vane passage partition wall that is involved in the formation of the inter-vane passage section adjacent to the above.

  As shown in FIG. 2, the bearing housing side flange 3 and the nozzle wall surface flange 5 are spaced apart from each other at a predetermined interval in the thrust direction, and therefore, between the annular front end portion of the flange 3 and the outer peripheral portion of the nozzle wall surface flange 5. An annular gap is secured in. The annular tunnel-shaped exhaust gas passage 11 and the accommodation chamber 15 of the exhaust turbine T (shown by a two-dot chain line) set in the inner central region of the turbine housing can communicate with each other through the annular gap. When the exhaust turbine T is accommodated in the exhaust turbine accommodating chamber 15, a thrust clearance C1 (also referred to as “inlet-side clearance”) and a gap between the outer peripheral portion of the exhaust turbine T and the inner peripheral portion of the nozzle wall surface flange 5 are provided. A radial clearance C2 (also referred to as “exit side clearance”) is secured. These clearances C1 and C2 correspond to the tip clearance between the turbine housing and the exhaust turbine T.

  As shown in FIGS. 1 (A), 1 (C) and FIG. 3, the flange-like skirt portion 6b of the annular reinforcing member 6 and the wall around the outlet hole of the scroll body 1 that are overlapped to form the front side multiple wall of the turbine housing. A plurality (three in this example) of bolt holes 16 for attaching the variable nozzle vanes 20 to the turbine housing are formed through the 1b and the nozzle wall surface flange 5.

  As shown in FIGS. 2 and 3, a metal short cylindrical ring-shaped connecting ring 8 is interposed between the bearing housing side flange 3 and the nozzle wall surface flange 5. Both flanges 3 and 5 are connected to each other. More specifically, as shown in FIGS. 5 and 6, the connecting ring 8 includes a plurality of ventilation slits S (three in this example) extending in the circumferential direction and a plurality of columnar shapes existing between the ventilation slits S. It has a connecting portion 81 (three columns in this example), and a front end side annular portion 82 and a rear end side annular portion 83 that are respectively positioned before and after the group of ventilation slits S. That is, the front end side annular portion 82 and the rear end side annular portion 83 are interconnected via the three columnar connecting portions 81. The ventilation slit S provides a radial exhaust gas passage that connects the central region of the turbine housing including the exhaust turbine housing chamber 15 and the annular tunnel exhaust gas passage 11.

  The front end side annular portion 82 of the connection ring is welded to the outer peripheral portion of the nozzle wall surface flange 5 (W6), and the rear end side annular portion 83 of the connection ring is the inner peripheral portion of the bearing housing side flange 3. The connection ring 8 (more essentially, the columnar connection portion 81 of the connection ring) is engaged with the annular step portion 3a formed on the inner periphery of the flange 3 and welded to the inner periphery of the flange 3 (W7). The bearing housing side flange 3 and the nozzle wall surface flange 5 are firmly connected. The wall thickness of the connecting ring 8 is preferably 1.0 to 5.0 mm. When it is desired to improve the strength and heat resistance by making the connecting ring 8 relatively thick, for example, two plate-like rings having a thickness of 2 mm may be overlapped to form a connecting ring 8 having a thickness of 4 mm.

  As shown in FIGS. 3, 4, and 6, each of the columnar connecting portions 81 is formed so that its cross-sectional shape forms a fan shape. Exhaust gas guiding inclined surfaces 84 are formed on both side surfaces of each columnar connecting portion 81 (that is, side surfaces along two sides other than the inner arc and the outer arc in the sector cross section). The inclined surface 84 for guiding the exhaust gas has an inner edge E1 connected to one end of the inner arc in the sector cross section and an outer edge E2 connected to one end of the outer arc in the sector cross section. The inclined surface 84 is formed to have a predetermined inclination angle θ with respect to a radial line connecting the turbo axis center C and the inner edge E1 of the inclined surface 84.

  The inclination angle θ of the inclined surface 84 is related to the opening of the variable nozzle vane 20 (more specifically, the attachment angle of the vane 21 and the variable angle range thereof) to be disposed in the inner region of the connecting ring 8. Decided in consideration. In the present embodiment, the inclination angle θ of the inclined surface 84 is set to about 45 °, but the inclination angle θ is preferably set in the range of 30 ° to 60 °. This is because when the inclination angle θ is smaller than 30 °, the exhaust gas induction effect by the inclined surface 84 is reduced, and the provision of the columnar connecting portion 81 may increase the ventilation resistance in the turbine housing. On the other hand, when the inclination angle θ is larger than 60 °, not only the exhaust gas induction effect by the inclined surface 84 is lowered, but also the column width of the columnar connecting portion 81 is widened, so that the ventilation sectional area of the ventilation slit S is relatively increased. As a result, the ventilation resistance in the turbine housing may be excessively increased.

  When the connection ring 8 is fixed in the turbine housing, the three columnar connection portions 81 of the connection ring are respectively located in the vicinity of the three variable nozzle vane mounting bolt holes 16 penetratingly formed in the nozzle wall surface flange 5 and the scroll body 1. The connecting ring 8 is positioned with respect to the scroll body 1 so as to be positioned. Specifically, as shown in FIG. 4, an inner arc (an arc connecting the inner edges E <b> 1 and E <b> 1 of the two inclined surfaces 84) in the sector cross section of each columnar connecting portion 81 faces the bolt hole 16. Alternatively, the connecting ring 8 is positioned so that each columnar connecting portion 81 is positioned on an extension of a radial line connecting the turbo shaft center C and the center of the bolt hole 16. Further, the minimum value (that is, the distance or interval between the inner edges E1, E1 in FIG. 4) of the circumferential column width of each columnar connecting portion 81 is substantially equal to the diameter of the bolt hole 16 (that is, the diameter of the mounting bolt) or It is set below that.

  In the present embodiment, the columnar coupling portion 81 of the coupling ring has a fan-shaped column shape in cross section, the inclined surface 84 for exhaust gas guidance having an inclination angle θ is formed on the side portion of the columnar coupling portion 81, and the columnar coupling portion. 81 is arranged in the vicinity of the bolt hole 16 for mounting the variable nozzle vane, and the minimum value of the circumferential column width of the columnar connecting portion 81 is substantially equal to or less than the diameter of the bolt hole 16 (that is, the diameter of the mounting bolt). Due to the synergistic effect of the setting, the ventilation resistance of the radial exhaust gas passage from the annular tunnel-like exhaust gas passage 11 of the scroll body to the variable nozzle vane 20 via the ventilation slit S is minimized.

  By the way, the turbine housing of this embodiment is used in the state where the variable nozzle vane 20 is incorporated in the turbine housing in the exhaust turbine portion of the turbocharger. During operation of the turbocharger, exhaust gas from the engine enters the annular tunnel exhaust gas passage 11 through the inlet hole 13, is guided to the guide member 14, and flows in the passage 11 in one direction. The exhaust gas flowing through the exhaust gas passage 11 acts on the exhaust turbine T disposed in the central region of the turbine housing through the ventilation slit S and the inter-vane passage of the variable nozzle vane 20, and then downstream through the outlet hole 12. Discharged to the side. The flow rate or flow velocity of the exhaust gas acting on the exhaust turbine T is controlled by adjusting the opening of the variable nozzle vane 20 (that is, the communication cross-sectional area of the passage between the vanes corresponding to the inclination angle of the vane 21). That is, when the engine rotates at a low speed (when the exhaust gas flow rate is small), the opening speed of the variable nozzle vane 20 is reduced to increase the flow rate of the exhaust gas passing through the intervane passage and increase the supercharging pressure. On the other hand, when the engine rotates at high speed (when the exhaust gas flow rate is large), the opening of the variable nozzle vane 20 is greatly opened to reduce exhaust resistance and increase the exhaust gas flow rate passing through the intervane passage. Increase the supply pressure.

  Since control is performed to reduce the opening of the variable nozzle vane 20 when the engine rotates at a low speed, the cross-sectional area and cross-sectional shape of the exhaust gas passage 11 of the turbine housing are substantially constant over the entire circumference, or the gradually changing cross-sectional shape is Whether it is adopted has little effect on the supercharging performance. On the other hand, when the engine rotates at a high speed, control is performed so that the opening of the variable nozzle vane 20 is greatly opened, so that the cross-sectional area and the cross-sectional shape of the exhaust gas passage 11 of the turbine housing are substantially constant over the entire circumference. Whether or not a gradually changing cross-sectional shape is adopted greatly affects the supercharging performance.

  For example, in the case of a conventional turbine housing adopting a gradually changing cross-sectional shape (comparative example in FIG. 7), the passage cross-sectional area is larger than the maximum opening of the variable nozzle vane 20 in a part of the exhaust gas passage 11 of the turbine housing. There is a narrowed portion (narrow cross section), and therefore the gas flow passing through the turbine housing is governed not by the opening of the variable nozzle vane 20 but by the passage cross sectional area of the narrow cross section in the exhaust gas passage 11. That is, the narrow cross section in the exhaust gas passage 11 determines the magnitude of the pressure loss in the exhaust turbine portion of the turbocharger, and considerably reduces the supercharging performance. On the other hand, in the present embodiment, since the cross-sectional area and the cross-sectional shape of the exhaust gas passage 11 are substantially constant over the entire circumference, the passage cross-sectional area of the exhaust gas passage 11 is made larger than the maximum opening of the variable nozzle vane 20 in advance. I can leave. Therefore, the supercharging pressure control corresponding to the changeable range of the opening degree of the variable nozzle vane 20 can be realized, and the pressure loss of the exhaust turbine section at the time of the maximum opening degree of the variable nozzle vane 20 can be reduced as compared with the comparative example of FIG. Thus, the supercharging performance can be improved.

  In order to support the above consideration, the characteristics of the turbine housing according to the present embodiment and the comparative example were evaluated. Specifically, a turbocharger with a variable nozzle vane using the turbine housing of the present embodiment and a turbocharger with a variable nozzle vane using a conventional turbine housing (comparative example of FIG. 7) are prepared, and each is the same type of engine. Assembled. An engine full load performance evaluation test was conducted for each engine. In this evaluation test, the conditions were unified so that the relationship between the engine speed and the opening degree of the variable nozzle vane 20 was the same, and the supercharging performance of the two turbochargers could be compared. FIG. 8 is a graph showing the results of the evaluation test. The horizontal axis in FIG. 8 indicates the engine speed, and the vertical axis indicates the engine output. As described above, in an engine with a turbocharger, the opening degree of the variable nozzle vane 20 is reduced when the engine is rotating at a low speed, and the opening degree of the variable nozzle vane 20 is greatly increased as the engine speed becomes higher than when the engine is rotating at a low speed. It is. As a matter of course, the higher the engine output at the same engine speed, the higher the turbocharger supercharging performance is evaluated.

  As can be seen from FIG. 8, when the engine speed is in the range from low speed to medium speed (that is, when the opening of the variable nozzle vane 20 is reduced), there is almost no difference in engine output between this embodiment and the comparative example. However, when the engine speed is in the range from medium speed to high speed (that is, when the opening of the variable nozzle vane 20 is wide open), the engine output of the turbocharged engine using the turbine housing of this embodiment is a comparative example. Always above. That is, when the opening degree of the variable nozzle vane 20 becomes large (when the engine rotates at high speed), the supercharging performance of the present embodiment is clearly superior to that of the comparative example. The results in FIG. 8 confirm the above considerations.

[Effect of the embodiment]
According to the present embodiment, the mechanical rigidity and the dimensional stability are enhanced by directly connecting the bearing housing side flange 3 and the nozzle wall surface flange 5 with the connection ring 8 having the plurality of columnar connection portions 81. . Therefore, even if the scroll body 1 and peripheral components of the turbine housing (for example, exhaust manifold, turbo elbow, etc.) are thermally deformed by the heat of the exhaust gas, the flanges on the bearing housing side connected to each other by the columnar connecting portion 81 of the connecting ring 3 and the nozzle wall surface flange 5 are not significantly affected by the thermal deformation. That is, the relative arrangement relationship or dimensional relationship between the bearing housing side flange 3 and the nozzle wall surface flange 5 that determines the tip clearances C1 and C2 between the turbine housing and the exhaust turbine T hardly changes. Thus, according to the present embodiment, changes in the chip clearances C1 and C2 due to thermal deformation or the like can be prevented as much as possible. Further, if the advantage that the change in the tip clearances C1 and C2 can be prevented even when the scroll body 1 is thermally deformed, the scroll body 1 can be thinned to reduce the weight and the heat capacity of the turbine housing. Costs can be reduced by making the constituent material of the main body 1 cheaper.

  In the present embodiment, since the plurality of columnar connecting portions 81 are grouped into a single part called the connecting ring 8, only by accurately positioning the connecting ring 8 with respect to the bearing housing side flange 3 and the nozzle wall surface flange 5, The individual columnar connecting portions 81 can be positioned at a time with respect to both the flanges 3 and 5, and the assembling property of the plurality of columnar connecting portions 81 with respect to the turbine housing can be improved.

  In the present embodiment, there is a columnar connecting portion 81 that becomes an obstacle (cause of increased ventilation resistance) in the middle of the gas flow path connecting the annular tunnel-shaped exhaust gas passage 11 and the exhaust turbine housing chamber 15. Become. However, as described above, the columnar connecting portion 81 of the connecting ring has a fan-shaped columnar cross section, the exhaust gas guiding inclined surface 84 having the inclination angle θ is formed on the side of the columnar connecting portion 81, and the columnar connecting The portion 81 is disposed in the vicinity of the bolt hole 16 for mounting the variable nozzle vane, and the minimum value of the circumferential column width of the columnar connecting portion 81 is substantially equal to or less than the diameter of the bolt hole 16 (that is, the diameter of the mounting bolt). As a result of the synergistic effect, the ventilation resistance of the radial exhaust gas passage from the annular tunnel-like exhaust gas passage 11 of the scroll body to the variable nozzle vane 20 via the ventilation slit S can be minimized. Therefore, the provision of the columnar connecting portion 81 inside the turbine housing does not lead to a decrease in turbocharging performance of the turbocharger, and it is possible to prevent changes in the tip clearances C1 and C2 due to thermal deformation as described above. Since the surface is large, the supercharging performance is improved or stabilized rather than the conventional structure without the columnar connecting portion 81.

  According to the present embodiment, the annular tunnel-shaped exhaust gas passage 11 is formed so that the cross-sectional area and the cross-sectional shape thereof are substantially constant over the entire circumference thereof. It can be set larger than the cross-sectional area of the passage between the vanes corresponding to the position at the time of maximum opening. Therefore, a part of the annular tunnel-like exhaust gas passage 11 is prevented from becoming a bottleneck and the effect of the nozzle vanes is prevented, and the turbocharger supercharging performance can be improved as compared with the comparative example. In particular, as shown in FIG. 8, when the variable nozzle vane 20 tends to open, the engine output can be increased as compared with the comparative example.

  In addition, the annular tunnel-like exhaust gas passage 11 is formed so that not only the cross-sectional area but also the cross-sectional shape is substantially constant over the entire circumference of the exhaust gas passage 11, the symmetry of the scroll body 1 with respect to the central axis C is improved. Even if the turbine housing undergoes thermal expansion during operation of the turbocharger, the thermal expansion is substantially uniform in all directions about the central axis C. Therefore, a machine in which the turbine housing is inclined with respect to the central axis C due to the non-uniformity (or non-uniform orientation) of thermal expansion, and as a result, the turbine housing and the exhaust turbine T interfere with each other. It is hard to cause an obstacle. In addition, the fact that the scroll body 1 has uniform thermal deformation characteristics in all directions as described above facilitates the thinning of the scroll body 1 and facilitates the construction of a turbocharger having a small heat capacity.

  Since the ring-shaped flange cover 7 is provided to cover the entire circumference of the portion of the bearing housing side flange 3 facing the scroll body outer peripheral portion 1a so that the high temperature exhaust gas does not directly contact the bearing housing side flange 3. As a constituent material of the housing side flange 3, a relatively inexpensive material (for example, a normal grade ferrous metal) can be used instead of an expensive high heat resistant material. Further, since the high temperature exhaust gas is not directly applied to the bearing housing side flange 3 having a relatively large heat capacity, the temperature drop of the exhaust gas flowing in the turbine housing can be suppressed as much as possible. As a result, the engine can be started cold. Early warm-up at the time and early activation of the exhaust gas purification catalyst can be achieved.

  [Modification] In the above embodiment, at the stage of assembling the turbine housing, the bearing housing side flange 3 and the nozzle wall surface flange 5 are connected by the connecting ring 8 having the columnar connecting portions 81 between the slits S. As shown in FIG. 9, the bearing housing side flange 3, the nozzle wall surface flange 5, and the plurality of columnar connecting portions 81 may be prepared as a single cast part integrally cast in advance. In this case, the positional relationship between the bearing housing side flange 3 and the nozzle wall surface flange 5 is substantially determined at the casting stage.

  [Modification] As shown in FIG. 10 and FIG. 11, the bearing housing side flange cover 7 and the connecting ring 8 are prepared as a single part that is integrally molded in advance, so that the number of parts during assembly can be reduced. Good. In that case, as shown in FIG. 11 in particular, it is preferable that the connecting ring 8 portion is integrally formed while the plate-like cylindrical portion connected to the inner peripheral portion of the flange cover 7 is formed into a two-ply structure. By making the connecting ring 8 part into a two-ply structure, the thickness of the columnar connecting portion 81 of the connecting ring 8 is increased and the strength is increased.

An example of a turbine housing is shown, (A) is a front view, (B) is a side view, (C) is a rear view. The radial direction sectional view in the AA line of Drawing 1 (A). Sectional drawing in the BB line of FIG. 1 (B). The enlarged view which shows the cross-sectional shape of a columnar connection part, and the outline of the vicinity. The perspective view which shows the whole short cylindrical connection ring. The partial perspective view which shows a part of short cylindrical connection ring. The graph which shows the relationship between each position of a cyclic | annular tunnel-shaped exhaust gas channel | path, and channel | path sectional area. The graph which shows the result of an engine full load performance evaluation test. The perspective view which shows the integral casting component in the example of a change (the 1). The perspective view which shows the integrally molded component in the example of a change (the 2). Radial direction sectional drawing equivalent to FIG. 2 in the example of a change (the 2).

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Scroll body, 2 ... Outlet flange, 3 ... Bearing housing side flange, 4 ... Inlet flange, 5 ... Nozzle wall surface flange, 7 ... Bearing housing side flange cover, 8 ... Connection ring, 10 ... Annular heat insulation space, 11 ... An annular tunnel-shaped exhaust gas passage, 12 ... outlet hole (exhaust gas outlet), 13 ... inlet hole (exhaust gas inlet), 16 ... variable nozzle vane mounting bolt hole, 20 ... variable nozzle vane, 81 ... columnar connecting portion, 82 ... Front end side annular part, 83 ... Rear end side annular part, 84 ... Inclined surface for exhaust gas guidance, C ... Center axis (turbo axis center), E1 ... Inner edge of the inclined surface, E2 ... Outer edge of the inclined surface, S ... vent slit, T ... exhaust turbine.

Claims (8)

A turbine housing for a turbocharger with nozzle vanes,
A scroll body for defining an annular tunnel-shaped exhaust gas passage;
An exhaust gas inlet provided on a side of the scroll body;
An exhaust gas outlet provided at the front center of the scroll body;
A bearing housing side flange provided on the back side of the scroll body as a joint for connecting the turbine housing to a bearing housing that rotatably supports the exhaust turbine;
As a restricting portion for positioning the nozzle vane in the thrust direction with respect to the scroll body, a nozzle wall surface flange provided in a central area of the scroll body and in the vicinity of the exhaust gas outlet,
A turbine housing comprising a plurality of columnar coupling portions for interconnecting the bearing housing side flange and the nozzle wall surface flange.   2. The turbine housing according to claim 1, wherein the bearing housing side flange, the nozzle wall surface flange, and the plurality of columnar connecting portions are formed as a single cast part integrally cast in advance. A turbine housing for a turbocharger with nozzle vanes,
A scroll body for defining an annular tunnel-shaped exhaust gas passage;
An exhaust gas inlet provided on a side of the scroll body;
An exhaust gas outlet provided at the front center of the scroll body;
A bearing housing side flange provided on the back side of the scroll body as a joint for connecting the turbine housing to a bearing housing that rotatably supports the exhaust turbine;
As a restricting portion for positioning the nozzle vane in the thrust direction with respect to the scroll body, a nozzle wall surface flange provided in a central area of the scroll body and in the vicinity of the exhaust gas outlet,
A coupling ring for interconnecting the bearing housing side flange and the nozzle wall surface flange;
The connection ring includes a plurality of ventilation slits extending in a circumferential direction and a plurality of columnar connection portions existing between the plurality of ventilation slits. The connection ring further includes an annular portion on a front end side and a rear end side sandwiching a group of the plurality of ventilation slits,
The annular portion at one end of the connecting ring is welded to the inner peripheral portion of the flange on the bearing housing side, and the annular portion at the other end of the connecting ring is welded to the outer peripheral portion of the nozzle wall surface flange. Item 4. The turbine housing according to Item 3.   The bearing housing side flange further includes a ring-shaped bearing housing side flange cover for covering a part of the flange facing the scroll body over the entire circumference, the bearing housing side flange cover including the flange cover, the bearing housing side flange, An annular heat-insulating space is defined between the scroll body and the annular tunnel-shaped exhaust gas passage. The bearing housing side flange cover and the connection ring are integrally formed in advance. The turbine housing according to claim 3, wherein the turbine housing is formed as a single component. Each of the plurality of columnar connecting portions has a fan-shaped cross section,
On one side surface of each columnar connecting portion, an exhaust gas guiding inclined surface along one side of the sector cross section connects the turbo shaft center (C) and the inner edge (E1) of the inclined surface in the radial direction. The turbine housing according to claim 1, wherein the turbine housing is formed so as to have an inclination angle (θ) of 30 ° to 60 ° with respect to the line.   The plurality of columnar connecting portions are respectively provided in the vicinity of bolt holes for mounting nozzle vanes formed in the scroll main body and / or the nozzle wall surface flange. The turbine housing according to the item.   The turbine according to any one of claims 1 to 7, wherein the annular tunnel-shaped exhaust gas passage is formed so that a cross-sectional area and a cross-sectional shape thereof are both substantially constant over the entire circumference. housing.

Images