JP2013104413A - Turbocharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold a variable nozzle mechanism in a pressed state against a bearing housing.SOLUTION: The present invention is directed to a turbocharger 10 in which a disc spring 50 is disposed in a gap G between a turbine housing 14 and an assembly 48 of a variable nozzle mechanism 30. The assembly 48 is biased in an axial direction of a turbine shaft 11 so as to be pressed against a bearing housing 12. A first heat shield part 42 extending to a turbine housing 14 side and positioned to a scroll passage 16 side rather than the disc spring 50 is provided at a shroud plate 41 of the assembly 48. A second heat shield part 18 extending to a shroud plate 41 side and positioned to the scroll passage 16 side rather than the disc spring 50 is provided at the turbine housing 14. In accordance with such a structure, a phenomenon in which exhaust gas E flowing through the scroll passage 16 directly impinges on the disc spring 50 is hindered by the second heat shield part 18 and the first heat shield part 42, and a temperature rise of the disc spring 50 due to the exhaust gas E is suppressed, and the decrease in biasing force is prevented.

Description

  The present invention relates to a turbocharger in which a variable nozzle mechanism that makes a flow rate of exhaust gas blown to a turbine wheel variable by opening and closing a variable nozzle is incorporated.

  As a turbocharger mounted on an engine, there is one in which a variable nozzle mechanism is incorporated in which a flow rate of exhaust gas sprayed on a turbine wheel is variable by opening and closing a variable nozzle. FIG. 4 shows an example.

  In the turbocharger 70, a turbine shaft (not shown) is rotatably supported by the bearing housing 71. A turbine housing 72 is disposed on one side (left side in FIG. 4) of the bearing housing 71 in the direction along the axis L1 of the turbine shaft. The turbine housing 72 has a turbine chamber 73 in the center, and has a spiral scroll passage 74 around the turbine chamber 73. A turbine wheel 75 that rotates in the turbine chamber 73 is provided on the turbine shaft. In the turbocharger 70, the exhaust E discharged from the engine and flowing along the scroll passage 74 is blown to the turbine wheel 75, and the turbine wheel 75 is rotationally driven. Along with this, a compressor wheel (not shown) coaxial with the turbine wheel 75 rotates integrally with the turbine wheel 75, and supercharging is performed (intake air is compressed and sent to the engine).

  A variable nozzle mechanism 80 having a plurality of variable nozzles 81 is provided between the scroll passage 74 and the turbine chamber 73. The variable nozzle mechanism 80 is a mechanism that varies the flow rate of the exhaust E sprayed to the turbine wheel 75 by changing the opening degree of the variable nozzle 81. As the flow rate of the exhaust E changes, the rotational speed of the turbocharger 70 is changed to adjust the supercharging pressure (intake pressure) of the engine.

  Further, in the turbocharger 70, a disc spring 82 is disposed between the turbine housing 72 and the variable nozzle mechanism 80. The disc spring 82 contacts the variable nozzle mechanism 80 at the outer peripheral edge 83 and contacts the turbine housing 72 at the inner peripheral edge 84 in a state in which the disk spring 82 is elastically deformed so that the dimension in the direction along the axis L1 decreases. Yes. By this disc spring 82, the variable nozzle mechanism 80 is urged in the direction along the axis L <b> 1 and pressed against the bearing housing 71. By this pressing, the variable nozzle mechanism 80 is positioned in a floating state without being fixed to the bearing housing 71 and the turbine housing 72.

  In the turbocharger described in Patent Document 1, the disc spring 82 seals the gap G between the variable nozzle mechanism 80 and the turbine housing 72. Therefore, the exhaust E of the scroll passage 74 is restricted from leaking through the gap G.

JP 2009-47027 A

  However, in the conventional turbocharger 70 including Patent Document 1, the disc spring 82 is directly exposed to the exhaust E flowing in the scroll passage 74. The exhaust E heats the disc spring 82 and raises the temperature, thereby reducing the urging force (spring force). As a result, it may be difficult to keep the variable nozzle mechanism 80 pressed against the bearing housing 71.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a turbocharger that can hold a variable nozzle mechanism pressed against a bearing housing.

In the following, means for achieving the above object and its effects are described.
According to a first aspect of the present invention, there is provided a bearing housing in which a turbine shaft is rotatably supported, a turbine housing that is disposed on one side of the bearing housing in a direction along an axis of the turbine shaft, and has a turbine chamber. A turbine housing having a scroll passage around and a turbine wheel provided on the turbine shaft and rotating in the turbine chamber of the turbine housing, and exhausted from the engine and flowing along the scroll passage. A turbocharger that sprays on the turbine wheel to rotationally drive the turbine wheel, and has a plurality of variable nozzles between the scroll passage and the turbine chamber, and the turbine wheel is changed by changing an opening of the variable nozzle. The exhaust flow velocity A variable nozzle mechanism, a disc spring disposed between the turbine housing and the variable nozzle mechanism, for biasing the variable nozzle mechanism in a direction along the axis and pressing the variable nozzle mechanism against the bearing housing; The gist further includes a heat shield provided between the scroll passages.

  According to said structure, a variable nozzle mechanism is urged | biased by the direction along the axis line of a turbine shaft with a disc spring, and is pressed against a bearing housing. By this pressing, the variable nozzle mechanism is positioned in a floating state without being fixed to the bearing housing and the turbine housing.

  Here, when the disc spring is directly exposed to the exhaust gas flowing through the scroll passage, the disc spring is heated to increase the temperature, which may cause a decrease in the urging force. In this aspect, the heat shield portion is provided between the disc spring and the scroll passage. In the invention according to claim 1, the exhaust gas flowing through the scroll passage and directed to the disc spring is heated before reaching the disc spring. And is prevented from directly hitting the disc spring. Of the exhaust, the one that changes the direction of the flow and bypasses the heat shield will hit the disc spring. As a result, the temperature rise of the disc spring due to the exhaust is suppressed, the decrease of the urging force is suppressed, and the variable nozzle mechanism is kept pressed against the bearing housing.

  According to a second aspect of the present invention, in the first aspect of the invention, the variable nozzle mechanism includes a plate that supports the variable nozzle so that the variable nozzle can be opened and closed between the variable nozzle and the turbine housing. The plate is provided with a first heat shield portion that extends toward the turbine housing and is located closer to the scroll passage than the disc spring. At least a part of the heat shield portion is provided by the first heat shield portion. The gist is that it is configured.

  According to the above configuration, the first heat shield that extends from the plate to the turbine housing side and is positioned closer to the scroll passage than the disc spring is located between the disc spring and the scroll passage, and the exhaust gas flowing through the scroll passage is the disc spring. Prevent direct hits.

  The gist of the invention described in claim 3 is that, in the invention described in claim 2, the first heat shield part is formed by bending the plate toward the turbine housing.

According to said structure, a 1st heat shield part is integrally provided in a plate only by performing simple process of bending a plate to the turbine housing side.
The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the variable nozzle mechanism includes a plate that supports the variable nozzle so that the variable nozzle can be opened and closed, and the variable nozzle and the turbine housing. The turbine housing is provided with a second heat shield that extends toward the plate and is positioned closer to the scroll passage than the disc spring. The second heat shield is provided with the second heat shield. The gist is that at least a part of the heat section is configured.

  According to said structure, the 2nd heat insulation part extended from a turbine housing to the plate side and located in a scroll channel | path side rather than a disc spring is located between a disc spring and a scroll channel, and the exhaust_gas | exhaustion which flows through a scroll channel | path is disc spring Prevent direct hits.

  According to a fifth aspect of the present invention, in the first aspect of the invention, the variable nozzle mechanism includes a plate that supports the variable nozzle so as to be opened and closed between the variable nozzle and the turbine housing. The plate is provided with a first heat shield portion that extends toward the turbine housing and is positioned closer to the scroll passage than the disc spring. The turbine housing extends toward the plate and extends more than the disc spring. A gist is that a second heat shield portion is provided on the scroll passage side, and the heat shield portion is constituted by the first heat shield portion and the second heat shield portion.

  According to the above configuration, the first heat shield extending from the plate to the turbine housing side and located on the scroll passage side from the disc spring, and the first heat shield portion extending from the turbine housing to the plate side and located on the scroll passage from the disc spring. The two heat shields are both located between the disc spring and the scroll passage, and prevent exhaust flowing through the scroll passage from directly hitting the disc spring.

  Thus, the heat shield part between the disc spring and the scroll passage is constituted by the first heat shield part and the second heat shield part. And the disc spring will be in the state covered with the 1st heat shield part and the 2nd heat shield part from the both sides about the direction along an axis. Therefore, it is less likely that the exhaust directly hits the disc spring than when the disc spring is covered only from one side in the direction along the axis.

  The invention according to claim 6 is the invention according to claim 5, wherein the first heat shield part and the second heat shield part are provided at different locations in the radial direction of the turbine shaft. The gist.

  According to the above configuration, the exhaust flowing through the scroll passage flows through the first heat shield and the second heat shield provided at different locations in the radial direction of the turbine shaft before reaching the disc spring. It will be obstructed and it will be more difficult to hit the disc spring directly.

Here, when the second heat shield is provided closer to the scroll passage than the first heat shield, it is possible to configure a part of the inner wall surface of the scroll passage by the second heat shield. .
The gist of the invention according to claim 7 is that, in the invention according to claim 6, the first heat shield and the second heat shield overlap each other in the direction along the axis.

  According to the above configuration, the exhaust gas flowing through the scroll passage passes through the gap between the first heat shield part and the second heat shield part before reaching the disc spring. This gap becomes resistance to the flow of exhaust gas, and the exhaust gas is less likely to enter the gap between the turbine housing and the variable nozzle mechanism. This is also effective in restricting exhaust from directly hitting the disc spring.

  The invention according to claim 8 is the invention according to any one of claims 1 to 7, wherein the disc spring is elastically deformed so that a dimension in a direction along the axis is small. The variable nozzle mechanism is pressed against the bearing housing by contacting the variable nozzle mechanism at one of the outer peripheral edge and the inner peripheral edge and contacting the turbine housing at the other, and the variable nozzle mechanism and the turbine housing The gist is to seal the gap between them.

  According to said structure, a disc spring urges | biases the variable nozzle mechanism through the location which contacted the variable nozzle mechanism in one of an outer peripheral part and an inner peripheral part, and presses it against a bearing housing. The disc spring seals the gap between the variable nozzle mechanism and the turbine housing by contacting the variable nozzle mechanism on one of the outer peripheral edge and the inner peripheral edge and contacting the turbine housing on the other.

  Thus, since one member (disc spring) serves as both a biasing member that biases the variable nozzle mechanism and a seal member that seals the gap, the biasing member and the seal member are configured by different members. The number of turbocharger parts is small.

It is a figure showing one embodiment which materialized the present invention, and a fragmentary sectional view showing a schematic structure of a turbocharger in which a variable nozzle mechanism was built. It is a figure which shows a part of variable nozzle mechanism in one Embodiment, (A) is the side view seen from the left side of FIG. 1, (B) is the side view seen from the right side of FIG. FIG. 2 is a partial cross-sectional view showing, in an enlarged manner, a cross-sectional structure in a cross section different from that of FIG. The fragmentary sectional view which expands and shows the variable nozzle mechanism in the conventional turbocharger, and its peripheral part.

Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS.
The vehicle is equipped with an engine that burns an air-fuel mixture of air sucked into a combustion chamber through an intake passage and fuel supplied to the combustion chamber. This engine is provided with a turbocharger 10 shown in FIG. In the turbocharger 10, a turbine shaft 11 is rotatably supported by a bearing housing 12 by a bearing 13. A turbine housing 14 is disposed adjacent to one side (right side in FIG. 1) of the bearing housing 12 in the direction along the axis L1 of the turbine shaft 11 (hereinafter referred to as “axial direction”), and the other side (left side in FIG. 1). ), A compressor housing (not shown) composed of a plurality of members is disposed adjacently. The turbine housing 14 and the compressor housing are fastened to the bearing housing 12 respectively. The bearing housing 12, the turbine housing 14, and the compressor housing constitute a housing for the turbocharger 10.

  A cylindrical turbine chamber 15 extending in the axial direction is formed at the center of the turbine housing 14. A spiral scroll passage 16 is formed around the turbine chamber 15 in the turbine housing 14. The turbine chamber 15 and the scroll passage 16 are communicated with each other via a communication passage 17 (see FIG. 3).

  The inner wall surface 12A facing the communication passage 17 in the bearing housing 12 and the inner wall surface 14A facing the communication passage 17 in the turbine housing 14 are in a state orthogonal to or close to the axis L1. .

  A turbine wheel 26 that rotates in the turbine chamber 15 is fixed on one end (right side in FIG. 1) of the turbine shaft 11. A compressor wheel (not shown) that rotates in the compressor housing is fixed on the other end (left side in FIG. 1) of the turbine shaft 11.

  In the turbocharger 10 having the above basic configuration, the exhaust E discharged from the engine and flowing along the scroll passage 16 is blown to the turbine wheel 26 through the communication passage 17, and the turbine wheel 26 is rotationally driven. Is done. This rotation is transmitted to the compressor wheel via the turbine shaft 11. As a result, in the engine, the air sucked by the negative pressure generated in the combustion chamber as the piston moves is forced (supercharged) into the combustion chamber by the rotation of the compressor wheel of the turbocharger 10. In this way, the efficiency of filling the combustion chamber with air is increased.

  A variable nozzle mechanism (variable nozzle mechanism) 30 is incorporated in the turbocharger 10. The variable nozzle mechanism 30 changes the exhaust flow area of the communication passage 17 and makes the flow rate of the exhaust E sprayed to the turbine wheel 26 variable, thereby adjusting the rotational speed of the turbocharger 10 and forcing it into the combustion chamber. It is a mechanism for adjusting the amount of air sent.

  Next, a schematic configuration of the variable nozzle mechanism 30 will be described. 2A shows a state in which a part of the variable nozzle mechanism 30 (nozzle plate 31 and the like) is viewed from the left side of FIG. 1, and FIG. 2B shows a part of the variable nozzle mechanism 30 (nozzle plate 31). Etc.) as viewed from the right side of FIG. As shown in FIGS. 1, 2 </ b> A, and 2 </ b> B, the variable nozzle mechanism 30 includes a nozzle plate 31 and a unison ring 35 disposed in the communication path 17. The nozzle plate 31 and the unison ring 35 have an annular shape centered on the axis L1.

  In the nozzle plate 31, a plurality of shafts 32 are arranged at substantially equal angles on a circle centered on the axis L1. Each shaft 32 extends parallel to the axis L1 and is rotatably inserted into the nozzle plate 31. For each shaft 32, a variable nozzle (nozzle vane) 33 is fixed to one portion (right side in FIG. 1) exposed from the nozzle plate 31. In FIG. 1, the variable nozzle 33 is illustrated by a two-dot chain line. For each shaft 32, the base end portion of the arm 34 is fixed to the other end portion (left side in FIG. 1) exposed from the nozzle plate 31.

  The unison ring 35 has concave portions 36 at a plurality of locations on the inner peripheral surface. The tip portions of the arms 34 are engaged with these recesses 36. The unison ring 35 is rotated from the outside of the turbocharger 10 via a link 37 (see FIG. 1) or the like. In other words, the arm 39 is fixed to the rotation shaft 37 </ b> A of the link 37, and the tip of the arm 39 is engaged with the recess 40 provided on the inner peripheral surface of the unison ring 35. When the unison ring 35 is rotated around the axis L1 from the outside of the turbocharger 10 via the link 37, the rotation shaft 37A, the arm 39, etc., the unison ring 35 is engaged with the plurality of recesses 36 of the unison ring 35. The joined arms 34 are rotated (opened / closed) in synchronization with each other about the shaft 32. The opening degree of the variable nozzle 33 is changed by the rotation of each shaft 32, and the exhaust circulation area of the communication path 17 is changed. And the flow velocity of the exhaust E sprayed on the turbine wheel 26 through between the adjacent variable nozzles 33 is adjusted.

  For example, in FIG. 2A, when the arm 39 is rotated counterclockwise with the rotation axis 37A as a fulcrum by the link 37 or the like, the unison ring 35 is accompanied by the rotation of the unison ring 35 as shown in FIGS. In (B), it rotates in the direction indicated by the arrow. By the above-described rotation of the unison ring 35, each shaft 32 is rotated in the counterclockwise direction in FIG. 2A and in the clockwise direction in FIG. As the shafts 32 rotate, the variable nozzle 33 rotates toward the closing side, and the flow velocity of the exhaust E sprayed on the turbine wheel 26 increases. Contrary to the above, when the variable nozzle 33 rotates to the open side, the flow velocity of the exhaust E sprayed on the turbine wheel 26 decreases.

  FIG. 3 shows an enlarged cross-sectional structure of the variable nozzle mechanism 30 and its peripheral portion at a different cross section (cross section passing through a spacer 47 described later) from FIG. As shown in FIGS. 1 and 3, the variable nozzle mechanism 30 includes a shroud plate 41 disposed in the communication path 17 in addition to the above-described configuration. The shroud plate 41 corresponds to a “plate” in the claims, and has an annular shape centered on the axis L1. The shroud plate 41 is disposed on the side away from the bearing housing 12 with respect to the nozzle plate 31 (each right side in FIGS. 1 and 3). On the other hand, the shaft 32 for each variable nozzle 33 is exposed to the shroud plate 41 from the variable nozzle 33, and the exposed portion of the shaft 32 is rotatably inserted into the shroud plate 41. Accordingly, each variable nozzle 33 is supported by the nozzle plate 31 and the shroud plate 41 so as to be able to rotate integrally with the shaft 32.

  The shroud plate 41 is connected to the nozzle plate 31 by a plurality of pins 46 arranged at substantially equal angles on a circle centered on the axis L1. Each pin 46 is press-fitted into the nozzle plate 31 and the shroud plate 41.

  Between the nozzle plate 31 and the shroud plate 41, a circular tubular spacer 47 is put on each pin 46, and these spacers 47 provide a gap of about the thickness of the variable nozzle 33 between the nozzle plate 31 and the shroud plate 41. Is secured. As a result of the connection, the nozzle plate 31 and the shroud plate 41 form an “assembly 48” that is integrally coupled to each other.

  Further, in the turbocharger 10, an annular shape is formed around the turbine wheel 26 by an elastic body such as a metal plate in a gap G between the shroud plate 41 of the assembly 48 and the inner wall surface 14 </ b> A of the turbine housing 14. A disc spring 50 is disposed. This gap G is a bearing even if the turbine housing 14 or the like undergoes thermal deformation (shrinkage / expansion) when it is cold or hot, or there is a variation in accuracy in the components of the turbocharger 10. It is provided in consideration of the fact that an installation space for the assembly 48 can be secured between the housing 12 and the turbine housing 14.

  One function of the disc spring 50 is to urge the assembly 48 in the axial direction and press it against the inner wall surface 12 </ b> A of the bearing housing 12. Another function of the disc spring 50 is to seal the gap G. The disc spring 50 is formed in a conical shape (tapered shape) that approaches the inner wall surface 14 </ b> A of the turbine housing 14 as it approaches the center.

  The outer peripheral edge 52 of the disc spring 50 has an annular shape with the axis L1 as the center, and is in contact with the shroud plate 41 at locations farther from the axis L1 than all the shafts 32 and all the pins 46. The inner peripheral edge 51 of the disc spring 50 has an annular shape centering on the axis L <b> 1 and is in contact with the inner wall surface 14 </ b> A of the turbine housing 14.

  The disc spring 50 is bent (elastically deformed) in a direction in which the dimension in the axial direction is reduced by applying a load at the inner peripheral edge portion 51 and the outer peripheral edge portion 52. The assembly 48 (the shroud plate 41) is urged toward the bearing housing 12 in the axial direction. By this biasing, the nozzle plate 31 is pressed against the inner wall surface 12 </ b> A of the bearing housing 12.

Further, in the present embodiment, a heat shield is provided between the disc spring 50 and the scroll passage 16. In this embodiment, the heat shield portion includes a first heat shield portion 42 and a second heat shield portion 18.
The first heat shield 42 extends from the shroud plate 41 toward the turbine housing 14 and is positioned closer to the scroll passage 16 than the outer peripheral edge 52 of the disc spring 50. The first heat shield 42 is formed by bending the shroud plate 41 toward the turbine housing 14.

  The second heat shield 18 extends from the turbine housing 14 toward the shroud plate 41 and is located closer to the scroll passage 16 than the outer peripheral edge 52 of the disc spring 50. The second heat shield 18 is located at a location slightly away from the first heat shield 42 toward the scroll passage 16. In the second heat shield 18, the surface far from the axis L <b> 1 constitutes a part of the inner wall surface 16 </ b> A of the scroll passage 16. The tip surface of the second heat shield 18 is positioned closer to the bearing housing 12 than the tip surface of the first heat shield 42, and the second heat shield 18 is axial with respect to the first heat shield 42. It overlaps with.

As described above, the turbocharger 10 of the present embodiment is configured. Next, the operation of the turbocharger 10 will be described.
Exhaust E generated by the operation of the engine flows into the turbocharger 10 in the process of flowing through the exhaust passage and flows along the scroll passage 16 of the turbine housing 14. The exhaust E passes between adjacent variable nozzles 33 and is blown to the turbine wheel 26 in the turbine chamber 15. The turbine wheel 26 is rotationally driven by the blowing of the exhaust E. Accordingly, the compressor wheel coaxial with the turbine wheel 26 rotates integrally with the turbine wheel 26 to perform supercharging.

  When the variable nozzle 33 is rotated from the outside of the turbocharger 10 through the operation of the link 37 or the like, the opening degree of the variable nozzle 33 is changed. Along with this, the flow rate of the exhaust E sprayed on the turbine wheel 26 is changed, the rotational speed of the turbocharger 10 is changed, and the supercharging pressure of the engine is adjusted.

  By the way, in the turbocharger 10, the disc spring 50 is elastically deformed in the axial direction between the assembly 48 (the shroud plate 41) and the inner wall surface 14A of the turbine housing 14, and is incorporated in a state where elastic energy is accumulated. It is.

  The shroud plate 41 with which the outer peripheral edge 52 of the disc spring 50 is in contact is always urged in the axial direction by a force (elastic restoring force, urging force) for releasing the elastic energy of the disc spring 50. The biasing force of the disc spring 50 is transmitted to the nozzle plate 31 via the spacer 47 and the pin 46.

  The assembly 48 is displaced toward the bearing housing 12 by the transmission of the urging force. Then, the nozzle plate 31 is pressed against the inner wall surface 12 </ b> A of the bearing housing 12. By this pressing, the assembly 48 is positioned in a floating state without being fixed to the bearing housing 12 and the turbine housing 14.

  In the turbocharger 10, there is a gap G between the shroud plate 41 and the inner wall surface 14 </ b> A of the turbine housing 14, and this gap G is sealed by a disc spring 50.

  Here, when the disc spring 50 is directly exposed to the exhaust E flowing through the scroll passage 16, the disc spring 50 may be heated to increase the temperature, and the urging force may be reduced. In this regard, in the present embodiment, the first heat shield portion 42 that extends from the shroud plate 41 to the turbine housing 14 side and is located closer to the scroll passage 16 than the outer peripheral edge portion 52 of the disc spring 50 includes the disc spring 50 and the scroll passage. Located between 16. A second heat shield 18 that extends from the turbine housing 14 toward the shroud plate 41 and is located closer to the scroll passage 16 than the outer peripheral edge 52 of the disc spring 50 is located between the disc spring 50 and the scroll passage 16. The exhaust E from the scroll passage 16 toward the disc spring 50 hits the second heat shield 18 and the first heat shield 42 before reaching the disc spring 50 and is prevented from directly hitting the disc spring 50.

  In particular, in the present embodiment, the second heat shield 18 and the first heat shield 42 are located at different locations in the radial direction of the turbine shaft 11 between the disc spring 50 and the scroll passage 16. Therefore, the exhaust E flowing through the scroll passage 16 is blocked by the second heat shield 18 and the first heat shield 42 before reaching the disc spring 50, and may directly hit the disc spring 50. Less likely to occur. In the exhaust E, the flow direction is changed to bypass the first heat shield part 42 and the second heat shield part 18 and hit the disc spring 50.

  Furthermore, in this embodiment, since the 2nd heat shield part 18 and the 1st heat shield part 42 have overlapped in the direction in alignment with the axis line L1, before the exhaust E which flows through the scroll channel | path 16 reaches the disc spring 50, it is. A gap extending in the axial direction is passed between the first heat shield 42 and the second heat shield 18. This gap becomes a resistance to the flow of the exhaust E, and the exhaust E is difficult to enter the gap G. In this respect as well, it becomes difficult for the exhaust E to directly hit the disc spring 50.

  As described above, when the phenomenon that the exhaust E flowing through the scroll passage 16 directly hits the disc spring 50 is hindered, the temperature rise of the disc spring 50 by the exhaust E is suppressed, and the decrease in the urging force is suppressed.

According to the embodiment described in detail above, the following effects can be obtained.
(1) A disc spring 50 is disposed in the gap G between the turbine housing 14 and the assembly 48 of the variable nozzle mechanism 30, and the assembly 48 is urged in the axial direction of the turbine shaft 11 and pushed against the bearing housing 12. The target is the turbocharger 10 to which it is applied.

  The shroud plate 41 is provided with a first heat shield 42 that extends toward the turbine housing 14 and is positioned closer to the scroll passage 16 than the disc spring 50. The turbine housing 14 is provided with a second heat shield 18 that extends toward the shroud plate 41 and is positioned closer to the scroll passage 16 than the disc spring 50. As described above, the first heat shield portion 42 and the second heat shield portion 18 are provided between the disc spring 50 and the scroll passage 16.

Therefore, the first heat shield 42 and the second heat shield 18 can prevent the exhaust E flowing through the scroll passage 16 from directly hitting the disc spring 50.
Further, since the disc spring 50 is covered by the first heat shield portion 42 and the second heat shield portion 18 from both sides in the axial direction, the exhaust E is directly applied to the disc spring 50 rather than the case where the disc spring 50 is covered only from one side. You can make it harder to hit.

  As a result, the temperature rise of the disc spring 50 due to the exhaust E can be suppressed to suppress a decrease in the biasing force, and the assembly 48 of the variable nozzle mechanism 30 is held in a state of being pressed against the bearing housing 12. Can do.

  (2) The first heat shield portion 42 can be provided integrally with the shroud plate 41 only by performing simple processing such as bending the shroud plate 41 toward the turbine housing 14.

(3) The first heat shield part 42 and the second heat shield part 18 are provided at different locations in the radial direction of the turbine shaft 11.
Therefore, before the exhaust E flowing through the scroll passage 16 reaches the disc spring 50, the flow can be blocked by the second heat shield 18 and the first heat shield 42, and the exhaust E directly reaches the disc spring 50. The hitting phenomenon can be made more difficult to occur.

(4) The second heat shield 18 is positioned closer to the scroll passage 16 than the first heat shield 42.
Therefore, not only can the second heat shield 18 prevent the exhaust E flowing through the scroll passage 16 from directly hitting the disc spring 50, but the second heat shield 18 can also prevent a part of the inner wall surface 16 </ b> A of the scroll passage 16. Can be configured.

  (5) The tip surface of the second heat shield 18 is positioned closer to the bearing housing 12 than the tip surface of the first heat shield 42, and the second heat shield 18 is axial with respect to the first heat shield 42. Overlapping in the direction.

For this reason, the clearance between the first heat shield part 42 and the second heat shield part 18 can provide resistance to the exhaust flow and further restrict the exhaust E from hitting the disc spring 50 directly.
(6) The assembly 48 of the variable nozzle mechanism 30 is pressed against the bearing housing 12 and positioned only by the urging force of the disc spring 50. In other words, the assembly 48 is positioned in a floating state without being fixed to the housing (the bearing housing 12 and the turbine housing 14) of the turbocharger 10.

Therefore, the assembly 48 can be configured to be relatively small, the temperature difference in the components of the assembly 48 can be reduced, and thermal deformation at high temperatures can be reduced.
Further, since the assembly 48 is not forcibly fixed on the outer diameter side of the nozzle plate 31 or the like, it is possible to reduce constraints on deformation and reduce thermal deformation.

  For these reasons, even if the gap between the nozzle plate 31 and the variable nozzle 33 and the gap between the shroud plate 41 and the variable nozzle 33 are reduced, the variable nozzle 33 is freed from astringency at high temperatures. The astringency of the variable nozzle 33 is a phenomenon in which the variable nozzle 33 becomes difficult or unable to move due to contact with the nozzle plate 31 and the shroud plate 41 when the variable nozzle 33 rotates (opens and closes). As a result, it is possible to improve turbo performance, that is, improve turbine efficiency.

  (7) In a state where the disc spring 50 is elastically deformed so that the dimension in the axial direction becomes small, the outer peripheral edge portion 52 of the disc spring 50 is brought into contact with the shroud plate 41, and the inner peripheral edge portion 51 is brought into contact with the turbine housing 14. It is made to contact inner wall surface 14A.

  Therefore, the assembly 48 can be urged by the disc spring 50 and pressed against the inner wall surface 12A of the bearing housing 12, and the gap G between the assembly 48 of the variable nozzle mechanism 30 and the turbine housing 14 is sealed. can do.

  When one member (the disc spring 50) serves as both a biasing member that biases the shroud plate 41 and a seal member that seals the gap G, the biasing member and the seal member are configured by different members. Compared to the above, the number of parts of the turbocharger 10 can be reduced.

Note that the present invention can be embodied in another embodiment described below.
-In the above-mentioned embodiment, although the heat shield part was constituted by both the 1st heat shield part 42 and the 2nd heat shield part 18, the heat shield part may be constituted only by either one.

The first heat shield part 42 may be configured separately from the shroud plate 41. Similarly, the second heat shield 18 may be configured separately from the turbine housing 14.
The first heat shield part 42 and the second heat shield part 18 may be provided at the same location in the radial direction of the turbine shaft 11, that is, at the same distance from the axis L <b> 1. In this case, the first heat shield 42 and the second heat shield 18 face each other in the direction along the axis L <b> 1 between the disc spring 50 and the scroll passage 16.

  -When the 1st heat shield part 42 and the 2nd heat shield part 18 are provided in the mutually different location (location different distance from the axis line L1) in the radial direction of the turbine shaft 11, even if it does not necessarily overlap in an axial direction Good.

  In the above embodiment, the disc spring 50 has the function of biasing the assembly 48 of the variable nozzle mechanism 30 and the function of sealing the gap G between the assembly 48 and the turbine housing 14. The function to be performed may be performed by a member different from the disc spring 50. For example, the member to be sealed may be constituted by a gasket.

  The first heat shield part 42 may be provided in the shroud plate 41 at a plurality of different locations in the radial direction of the turbine shaft 11. Similarly, the second heat shield portion 18 may be provided at a plurality of different locations in the radial direction of the turbine shaft 11 in the turbine housing 14.

  The first heat shield part 42 may be provided closer to the scroll passage 16 than the second heat shield part 18.

  DESCRIPTION OF SYMBOLS 10 ... Turbocharger, 11 ... Turbine shaft, 12 ... Bearing housing, 14 ... Turbine housing, 15 ... Turbine chamber, 16 ... Scroll passage, 18 ... Second heat insulation part, 26 ... Turbine wheel, 30 ... Variable nozzle mechanism, 33 ... variable nozzle, 41 ... shroud plate (plate), 42 ... first heat shield part, 50 ... disc spring, 51 ... inner peripheral part, 52 ... outer peripheral part, E ... exhaust, G ... gap, L1 ... axis.

Claims (8)

A bearing housing on which the turbine shaft is rotatably supported;
A turbine housing disposed on one side of the bearing housing in a direction along the axis of the turbine shaft, having a turbine chamber, and having a scroll passage around the turbine chamber;
A turbine wheel provided on the turbine shaft and rotating in the turbine chamber of the turbine housing;
A turbocharger that blows exhaust gas discharged from an engine and flows along the scroll passage to the turbine wheel to rotate the turbine wheel;
A variable nozzle mechanism having a plurality of variable nozzles between the scroll passage and the turbine chamber, and changing a flow rate of exhaust gas blown to the turbine wheel by changing an opening of the variable nozzle;
A disc spring disposed between the turbine housing and the variable nozzle mechanism and biasing the variable nozzle mechanism in a direction along the axis to press it against the bearing housing;
The turbocharger further comprising a heat shield provided between the disc spring and the scroll passage. The variable nozzle mechanism includes a plate that supports the variable nozzle so as to be opened and closed between the variable nozzle and the turbine housing.
The plate is provided with a first heat shield portion that extends toward the turbine housing and is positioned closer to the scroll passage than the disc spring. At least a part of the heat shield portion is provided by the first heat shield portion. The turbocharger according to claim 1, wherein: The turbocharger according to claim 2, wherein the first heat shield part is formed by bending the plate toward the turbine housing. The variable nozzle mechanism includes a plate that supports the variable nozzle so as to be opened and closed between the variable nozzle and the turbine housing.
The turbine housing is provided with a second heat shield that extends toward the plate and is positioned closer to the scroll passage than the disc spring. At least a part of the heat shield is provided by the second heat shield. The turbocharger according to any one of claims 1 to 3, wherein: The variable nozzle mechanism includes a plate that supports the variable nozzle so as to be opened and closed between the variable nozzle and the turbine housing.
The plate is provided with a first heat shield that extends toward the turbine housing and is positioned closer to the scroll passage than the disc spring.
The turbine housing is provided with a second heat shield portion that extends toward the plate and is positioned closer to the scroll passage than the disc spring.
2. The turbocharger according to claim 1, wherein the heat shield portion is configured by the first heat shield portion and the second heat shield portion. The turbocharger according to claim 5, wherein the first heat shield portion and the second heat shield portion are provided at different locations in the radial direction of the turbine shaft. The turbocharger according to claim 6, wherein the first heat shield and the second heat shield overlap each other in a direction along the axis. The disc spring is elastically deformed so that the dimension in the direction along the axis is small, and contacts the variable nozzle mechanism at one of the outer peripheral edge and the inner peripheral edge, and contacts the turbine housing at the other. The turbocharger according to claim 1, wherein the variable nozzle mechanism is pressed against the bearing housing and the gap between the variable nozzle mechanism and the turbine housing is sealed.