JPWO2011105090A1 - Variable capacity turbocharger - Google Patents

Abstract

There is a gap 19 between the rear exhaust introduction wall 51 of the exhaust nozzle 9 that holds the nozzle vane 15 between the front exhaust introduction wall 10 and the rear exhaust introduction wall 51 and the turbine housing 1, and the exhaust gas in the scroll passage 8 is a gap. In order to prevent leakage to the turbine impeller 4 side through 19, a sealing device 25 is installed upstream of the exhaust gas from the position of the through hole 24 for penetrating the vane shaft 16 a provided in the rear exhaust introduction wall 51. In the turbocharger, each of the front exhaust introduction wall 10 and the rear exhaust introduction wall 51 is formed into a disc shape, and the stepped portion 50 in which the disc-shaped rear exhaust introduction wall 51 is fitted with the gap 19 is connected to the turbine. The housing 1 is provided.

Description

  The present invention relates to a variable displacement turbocharger that can improve turbine efficiency with a simple configuration and that enables smooth operation of nozzle vanes.

  FIG. 1 is a longitudinal sectional view showing the overall structure of a variable capacity turbocharger to which the present invention is applied. In this turbocharger, a turbine housing 1 and a compressor housing 2 are integrally assembled by fastening bolts 3 a and 3 b via a bearing housing 3, and a turbine impeller 4 disposed in the turbine housing 1 and an inside of the compressor housing 2 are assembled. A compressor impeller 5 disposed on the turbine housing 7 is connected to a bearing housing 3 by a turbine shaft 7 rotatably supported via a bearing 6.

  On the turbine housing side of the bearing housing 3, an exhaust nozzle 9 for guiding exhaust gas introduced into the scroll passage 8 of the turbine housing 1 to the turbine impeller 4 is provided.

  The exhaust nozzle 9 is integrated by, for example, fixing members 12 provided at three locations in the circumferential direction in a state where a front exhaust introduction wall 10 on the bearing housing 3 side and a rear exhaust introduction wall 11 on the turbine housing 1 side maintain a predetermined interval. Is assembled. Further, a mounting member 13 is fixed to the front surface (side surface of the bearing housing 3) of the front exhaust introduction wall 10, and when the turbine housing 1 and the bearing housing 3 are assembled, the mounting member 13 is connected to the turbine housing 1 and the bearing. The exhaust nozzle 9 is fixed by being sandwiched between the housing 3. Further, the exhaust nozzle 9 is positioned with respect to the bearing housing 3 by the positioning pins 14 during the assembly.

  A plurality of nozzle vanes 15 are arranged at equal intervals in the circumferential direction between the front exhaust introduction wall 10 and the rear exhaust introduction wall 11. In FIG. 1, a vane shaft fixed coaxially on both sides of each nozzle vane 15. 16a and 16b penetrate the front exhaust introduction wall 10 and the rear exhaust introduction wall 11, respectively, and the nozzle vane 15 is rotatably supported in a state where both ends are supported. In FIG. 1, 17 a, 17 b, 17 c and 17 d are link type transmission mechanisms for adjusting the opening / closing angle of the nozzle vane 15, and 18 is a scroll passage formed in the compressor housing 2.

  Further, a space 19 is provided between the rear exhaust introduction wall 11 and the turbine housing 1 in the exhaust nozzle 9. This gap 19 is originally unnecessary, but the deformation and accuracy are caused by the fact that the turbine housing 1 undergoes thermal deformation between the cold time and the hot time, and there are variations in accuracy among the assembled parts. It is provided to absorb the variation of

  If the clearance 19 is present, the exhaust gas in the scroll passage 8 is unnecessarily leaked to the turbine impeller outlet 20 through the clearance 19. Therefore, the rear exhaust introduction wall 11 extends downstream to close the clearance 19. The extending portion 11 ′ is provided, and a sealing piston ring 21 is disposed between the outer peripheral surface of the extending portion 11 ′ and the inner surface 1 ′ of the turbine housing 1 facing the extending portion 11 ′. There has been proposed one that prevents gas leakage and absorbs thermal deformation (see Patent Document 1).

  In Patent Document 1, as shown in FIG. 1, an annular concave groove 22 is provided on the outer peripheral surface of the extending portion 11 ′ of the rear exhaust introduction wall 11, and normally two sealing piston rings 21 are provided in the concave groove 22. The sealing device 23 is configured by shifting the positions so that the respective notches do not overlap with each other, and the outer peripheral surface of the sealing piston ring 21 is applied to the inner surface 1 ′ of the turbine housing 1 by the elastic force. Gas leak is prevented by pressure bonding.

  In the turbocharger shown in FIG. 1, the sealing device 23 is devised in various ways in order to prevent gas leakage from the gap 19, but the structure of the sealing device 23 is devised in this way. However, it has been found that it is difficult to significantly improve the efficiency of the turbine and there is a limit.

  For this reason, the present inventors have conducted various examinations and tests on the factors affecting the turbine efficiency in addition to the gas leak problem. As a result, the turbine efficiency decreases when the exhaust gas disturbance at the turbine impeller outlet 20 is large. I found out.

  As in the sealing device 23 shown in FIG. 1, in the configuration including the sealing piston ring 21 between the outer peripheral surface of the extending portion 11 ′ of the rear exhaust introduction wall 11 and the inner surface 1 ′ of the turbine housing 1, the scroll passage Since the pressure in the gap 19 to which the pressure 8 directly acts becomes larger than the pressure in the exhaust nozzle 9, the exhaust gas having a high pressure in the gap 19 causes the clearance between the vane shaft 16b and the through hole 24 (see FIG. 2). It flows to the downstream of the exhaust nozzle 9 through. At this time, there is a clearance in advance between the nozzle vane 15 and the front exhaust introduction wall 10 and the rear exhaust introduction wall 11 so that the nozzle vane 15 can be rotated. There are individual differences depending on the charger. Accordingly, each vane shaft 16b of each nozzle vane 15 is pushed by the exhaust gas from the high-pressure gap 19 and the nozzle vane 15 moves toward the front exhaust introduction wall 10, whereby each nozzle vane 15 and rear exhaust introduction wall 11 It was found that clearance occurred during Accordingly, high-pressure exhaust gas flows downstream of the exhaust nozzle 9 through the clearance between each nozzle vane 15 and the rear exhaust introduction wall 11, and the exhaust gas flow greatly disturbs the exhaust gas at the outlet of the turbine impeller 4, and this disturbance The knowledge that the efficiency of a turbine falls was acquired.

  For this reason, the present applicant prevents the problem that the exhaust gas in the scroll passage 8 leaks to the turbine impeller 4 side through the gap 19, and the high-pressure exhaust gas in the gap 19 passes through the vane shaft 16a and its through hole 24 (see FIG. No. 2) and a turbocharger that has been prevented from flowing downstream of the exhaust nozzle 9 through the clearance between each nozzle vane 15 and the rear exhaust introduction wall 11 (Patent Document 2).

JP 2006-125588 A JP 2009-144545 A

  According to the turbocharger of Patent Document 2, it is possible to effectively improve the efficiency of the turbine by preventing the problem of gas leakage to the turbine impeller 4 side due to the gap 19 and the problem of turbulence of the exhaust gas at the outlet of the turbine impeller 4.

  However, in Patent Document 2, the entire front exhaust introduction wall 10 has a disk shape, but the rear exhaust introduction wall 11 has a disk portion on the outer peripheral side, as in Patent Document 1. On the other hand, the inner peripheral side is an extending portion 11 ′ bent toward the downstream side in the axial direction along the outer shape of the turbine impeller 4. For this reason, when heated by high-temperature exhaust gas, the disc-shaped front exhaust introduction wall 10 is deformed only in the direction in which the diameter increases as a whole, whereas the rear exhaust introduction having the extending portion 11 ′ is introduced. Since the wall 11 has a high rigidity strength of the extending portion 11 ′, deformation of the flat plate portion in the radial direction is suppressed by the extending portion 11 ′. For this reason, the flat plate portion is on the front exhaust introduction wall 10 side. Deforms to fall down. As a result, there is a concern that the flat plate portion may come into contact with the nozzle vane 15 and hinder the movement of the nozzle vane 15.

  The present invention has been made in view of the above problems, and can prevent a problem that the front exhaust introduction wall and the rear exhaust introduction wall are deformed in directions other than the radial direction with a simple configuration, and can ensure a stable movement of the nozzle vane. The present invention intends to provide such a variable capacity turbocharger.

  The present invention has a gap between the rear exhaust introduction wall of the exhaust nozzle that holds the nozzle vane between the front exhaust introduction wall and the rear exhaust introduction wall and the turbine housing, and the exhaust gas in the scroll passage passes through the gap through the turbine. In order to prevent leakage to the impeller side, this is a variable capacity turbocharger in which a sealing device is installed upstream of the exhaust gas from the position of the through hole for penetrating the vane shaft provided in the rear exhaust introduction wall. Each of the front exhaust introduction wall and the rear exhaust introduction wall has a disc shape, and a step portion in which the disc-shaped rear exhaust introduction wall is fitted with the gap is provided in the turbine housing. This relates to a capacity-type turbocharger.

  In the variable displacement turbocharger, it is preferable that the front exhaust introduction wall and the rear exhaust introduction wall have the same linear expansion coefficient.

  In the variable displacement turbocharger, the sealing device may be a sealing piston ring, and the sealing device may be a disc spring seal.

  According to the variable capacity turbocharger of the present invention, each of the front exhaust introduction wall and the rear exhaust introduction wall is formed into a disk shape, and a gap is formed in a step portion formed in the turbine housing with the disk-shaped rear exhaust introduction wall. Since the front exhaust introduction wall and the rear exhaust introduction wall are deformed in a direction other than the radial direction with a simple configuration, it is possible to secure a stable movement of the nozzle vane. Can have an effect.

It is a longitudinal section showing the whole structure of the variable capacity type turbocharger to which the present invention is applied. It is sectional drawing of the exhaust nozzle vicinity which shows one Example of this invention. It is sectional drawing which shows the exhaust nozzle unit assembled | assembled integrally with the exhaust nozzle of FIG. It is the front view which looked at the exhaust nozzle unit of FIG. 3a from III direction. It is sectional drawing which shows the other Example of this invention provided with the sealing device different from FIG. 4b is a front view of the disc spring seal of FIG. 4a. FIG. 4b is a cross-sectional view of yet another embodiment of the present invention with a sealing device similar to FIG. 4a.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 2 shows an embodiment of the present invention. In the variable capacity turbocharger of FIG. 1, the rear exhaust introduction wall 11 provided with the extending portion 11 ′ is a disc-shaped rear exhaust introduction wall 51. Thus, each of the front exhaust introduction wall 10 and the rear exhaust introduction wall 51 has a disk shape. The disc-shaped rear exhaust introduction wall 51 and the disc-shaped front exhaust introduction wall 10 are preferably formed of the same material or a material having an equivalent linear expansion coefficient. As described above, by making the linear expansion coefficients of the rear exhaust introduction wall 51 and the front exhaust introduction wall 10 equal, the vane shafts 16a and 16b fixed to both sides of the nozzle vane 15 are connected to the rear exhaust introduction wall 51 and the front exhaust introduction. It is always supported coaxially by the wall 10.

  On the other hand, the turbine housing 1 is formed with an extension 39 that extends to a position spaced apart from the outer peripheral surface of the rear exhaust introduction wall 51 by a predetermined distance. On the front surface, a step 50 is formed in which the rear exhaust introduction wall 51 is fitted with a gap 19. The gap 19 is set in consideration of the respective linear expansion coefficients so that the turbine housing 1 and the rear exhaust introduction wall 51 do not come into contact with each other.

  Further, in the form of FIG. 2, a sealing device 25 for preventing the exhaust gas in the scroll passage 8 from leaking to the turbine impeller 4 side through the gap 19 between the turbine housing 1 and the rear exhaust introduction wall 51 is provided with a vane. The shaft 16b is installed on the upstream side of the exhaust gas (on the scroll passage 8 side) from the position of the through hole 24 that penetrates the rear exhaust introduction wall 51.

  In the sealing device 25 of FIG. 2, a concave groove 22 extending in the circumferential direction is formed on the outer peripheral surface of the rear exhaust introduction wall 51, and the inner peripheral surface of the extension portion 39 and the outer peripheral surface of the rear exhaust introduction wall 51. A sealing piston ring 21 similar to that in the case of FIG. In the example of FIG. 2, two sealing piston rings 21 are arranged in the concave groove 22.

  In addition, a flange 35 formed so as to cover the through hole 24 is formed in a fixed portion of the vane shafts 16a and 16b fixed to the nozzle vane 15 so as to penetrate the front exhaust introduction wall 10 and the rear exhaust introduction wall 51. Provided. Providing such a flange 35 can suppress the problem that foreign matter enters the through hole 24 and the problem that exhaust gas moves to the gap 19 through the through hole 24. Furthermore, by using the pressure of the exhaust gas acting on the rod 35, a sufficient force for moving the nozzle vane 15 toward the rear exhaust introduction wall 51 can be obtained as will be described later.

  3A is a cross-sectional view of an exhaust nozzle unit assembled integrally with the exhaust nozzle 9 of FIG. 2, and FIG. 3B is a front view of the exhaust nozzle unit of FIG. The exhaust nozzle unit U has a vane shaft 16a in a through hole 24 between a disc-shaped rear exhaust introduction wall 51 having the concave groove 22 formed on the outer periphery and a disc-shaped front exhaust introduction wall 10. A plurality of nozzle vanes 15 penetrating through 16b are disposed, and a rotating ring 52 is held between the front exhaust introduction wall 10 and the mounting member 13 on the front surface (the right side surface in FIG. 3a). A guide ring 53 is disposed, and the rear exhaust introduction wall 51, the front exhaust introduction wall 10, the attachment member 13, and the guide ring 53 are fastened by the fixing members 12 provided at three locations, The exhaust nozzle unit U is assembled. The end of the vane shaft 16b of the nozzle vane 15 is fixed to the inner end of the transmission link 54, and the outer end of the transmission link 54 has the same number as the nozzle vane 15 on the inner peripheral surface of the rotating ring 52. The engaging recess 55 is formed at intervals. When the vane shaft 16b of one nozzle vane 15 is rotated by the transmission mechanism including the 17a, 17b, 17c, and 17d of FIG. 1, all the nozzle vanes 15 are identical through the transmission link 54 and the rotation ring 52. It is designed to rotate at an angle.

  The exhaust nozzle unit U assembled as shown in FIGS. 3a and 3b is fitted with the flat plate-shaped rear exhaust introduction wall 51 with a gap 19 in a step 50 provided on the front surface of the turbine housing 1 in FIG. In the combined state, the flange portion 13 ′ of the mounting member 13 is assembled by being sandwiched and fastened by the turbine housing 1 and the bearing housing 3.

  The configuration shown in FIG. 2 operates as follows.

  The variable capacity turbocharger shown in FIG. 2 includes an inner peripheral surface of an extension 39 in a step 50 provided on the front surface of the turbine housing 1, and a rear part of an exhaust nozzle unit U assembled as shown in FIGS. 3a and 3b. The sealing piston ring 21 is arranged between the groove 22 formed on the outer peripheral surface of the exhaust introduction wall 51, and the rear exhaust introduction wall 51 is fitted to the step portion 50. In this state, the mounting member 13 The flange portion 13 'is sandwiched between the turbine housing 1 and the bearing housing 3 shown in FIG. Then, the rear exhaust introduction wall 51 comes to be disposed with the gap 19 in the step portion 50 formed in the turbine housing 1.

  As described above, the front exhaust introduction wall 10 and the rear exhaust introduction wall 51 that constitute the exhaust nozzle 9 have a simple disk-shaped configuration, respectively, and therefore, the disk-shaped front exhaust introduction wall 10. And the rear exhaust introduction wall 51 is freely deformed only in the radial direction. Accordingly, the rear exhaust introduction wall 11 having the extending portion 11 ′ in FIG. 1 has a problem of deforming so as to fall in a direction other than the radial direction. However, in the configuration of FIG. 2, such deformation is suppressed. The problem that an excessive force acts on the nozzle vane 15 is prevented, so that the nozzle vane 15 can always maintain a stable rotational operation.

  Further, as described above, the sealing device 25 in which the sealing piston ring 21 is disposed between the inner peripheral surface of the extension 39 and the concave groove 22 formed in the outer peripheral surface of the rear exhaust introduction wall 51 includes the scroll passage 8. This prevents the problem that the exhaust gas leaks through the gap 19 between the turbine housing 1 and the rear exhaust introduction wall 51.

  Furthermore, since the sealing device 25 is installed on the upstream side (scroll passage 8 side) of exhaust gas from the position of the through hole 24 where the vane shaft 16b penetrates the rear exhaust introduction wall 51, the sealing device 25 However, the pressure P2 is low in the downstream gap 19 and the pressure P1 in the exhaust nozzle 9 is in a state of P1> P2. For this reason, the exhaust gas in the exhaust nozzle 9 flows into the gap 19 downstream of the sealing device 25 as indicated by an arrow B. Furthermore, since the nozzle vane 15 is pushed and displaced toward the rear exhaust introduction wall 51 due to the pressure difference of P1> P2, the clearance between each nozzle vane 15 and the rear exhaust introduction wall 51 is minimized. At this time, the vane shaft 16b penetrating the rear exhaust introduction wall 51 is provided with a flange 35 covering the through hole 24 in the fixing portion to the nozzle vane 15 so that the pressure of the exhaust gas in the exhaust nozzle 9 acts on the flange 35. Therefore, the flange 35 is pressed against the rear exhaust introduction wall 51 so as to close the through hole 24. Then, the leakage of the exhaust gas indicated by the arrow B is reduced, and the amount of exhaust gas guided to the turbine impeller 4 is increased, whereby the efficiency of the turbine impeller 4 is increased. Even if the spear 35 is not provided, the pressure P2 acting on the gap 19 of the vane shaft 16b becomes smaller than that in the case of FIG. 1, so that the nozzle vane 15 moves to the rear exhaust introduction wall 51 side. However, it is preferable to provide the flange 35 as described above because the nozzle vane 15 moves to the rear exhaust introduction wall 51 side more reliably.

  FIG. 4 a shows another embodiment of the present invention having a sealing device 25 different from that in FIG. 2, in which the turbine housing 1 is opposed to the vertical surface of the rear exhaust introduction wall 51 and has a gap. A stepped portion 27 that is recessed toward the turbine housing 1 from the inner peripheral side portion 26 is provided at the outer peripheral side position of the inner peripheral side portion 26 of the stepped portion 50 forming the stepped portion 19, and the stepped portion 27 and the rear exhaust introduction wall 51. A ring-shaped disc spring seal 28 is provided between the rear surface and the rear surface. The step portion 27 has a facing surface 27a that is parallel to the rear exhaust introduction wall 51 (perpendicular to the axial center line of the turbine impeller 4) and a diameter that decreases from the inner peripheral side portion 26 toward the turbine housing 1 side. It is formed by the annular taper surface 27b formed in this way. Note that the bottom surface of the stepped portion 27 may not be the tapered surface 27b, but may be a cylindrical surface having a constant diameter in the axial center line direction. Can hold. However, as described above, when the bottom surface of the stepped portion 27 is the tapered surface 27b, the disc spring seal 28 can be held more stably, and as a result, the sealing effect can be improved. Further, for example, when assembling a variable capacity turbocharger, it is possible to prevent a problem that the disc spring seal 28 moves and falls off the stepped portion 27.

  The disc spring seal 28 has a notch 38 in which a part on the circumference is notched with a width of about 0.2 to 0.8 mm as shown by a two-dot chain line in FIG. The disc spring seal 28 has a linear portion 30 that is bent so as to approach the facing surface 27a at a position close to the inner peripheral end 29, and then bent outward and abuts against the facing surface 27a. Thus, it has a substantially S-shape bent so as to approach the rear exhaust introduction wall 51 from the straight portion 30. And by having this substantially S shape, the inner peripheral end 29 of the disc spring seal 28 is easily press-fitted into the tapered surface 27b, and the press-fitted inner peripheral end 29 depends on the shape of the tapered surface 27b. It is difficult to get out of the stepped portion 27. Further, the outer peripheral end 31 of the disc spring seal 28 has an inclined portion 32 extending inclinedly from the straight portion 30 so as to approach the rear exhaust introduction wall 51, and the outer peripheral portion of the inclined portion 32 is the rear exhaust. After forming the curved portion 33 that contacts the introduction wall 51, the curved portion 33 is curved away from the rear exhaust introduction wall 51. Accordingly, the disc spring seal 28 has a substantially frustoconical shape in which the positions of the inner peripheral end 29 and the outer peripheral end 31 are shifted in the direction along the axial center line. Furthermore, the height in the axial center line direction due to the frustoconical shape of the disc spring seal 28 is such that when the inner peripheral end 29 is fitted to the tapered surface 27b and the linear portion 30 is brought into contact with the opposing surface 27a, A curved portion 33 on the outer periphery is formed at a height at which it is crimped to the rear surface of the rear exhaust introduction wall 51 with a predetermined force.

  The disc spring seal 28 installed by being fitted to the tapered surface 27b of the stepped portion 27 of FIG. 4a has a height in the axial center line direction between the straight portion 30 and the curved portion 33 due to the frustoconical shape of the disc spring seal 28. Since the distance between the opposing surface 27a and the rear surface of the rear exhaust introduction wall 51 is higher, the straight portion 30 of the disc spring seal 28 is crimped to the opposing surface 27a when the assembly of the variable displacement turbocharger is performed. The curved portion 33 at the outer peripheral end 31 of the disc spring seal 28 is pressure-bonded to the rear surface of the rear exhaust introduction wall 51. As described above, according to the sealing device 25 using the disc spring seal 28, it is possible to prevent the problem that the exhaust gas in the scroll passage 8 leaks through the gap 19 between the turbine housing 1 and the rear exhaust introduction wall 51.

  Also in the embodiment of FIG. 4a, the front exhaust introduction wall 10 and the rear exhaust introduction wall 51 constituting the exhaust nozzle 9 each have a simple disk-shaped configuration. The exhaust introduction wall 10 and the rear exhaust introduction wall 51 can be freely deformed only in the radial direction, and deformation in a direction other than the radial direction is suppressed, so that an unreasonable force acts on the nozzle vane 15. Therefore, the nozzle vane 15 can ensure a stable rotational operation.

  FIG. 5 shows another embodiment similar to the sealing device 25 shown in FIG. 4 a, in which the turbine housing 1 forms a gap 19 so as to face the vertical surface of the rear exhaust introduction wall 51. A stepped portion 36 deeper than the stepped portion 27 of FIG. 4 a is provided at the outer peripheral position of the inner peripheral side portion 26, and a disc spring seal 37 is provided between the stepped portion 36 and the rear surface of the rear exhaust introduction wall 51. Provided. The step portion 36 is formed by a notch surface 36 a formed to face the rear exhaust introduction wall 51 and a cylindrical surface 36 b parallel to the axial center line of the turbine shaft 7.

  The disc spring seal 37 has a ring shape having a notch 38 in which a part of the circumference is notched with a width of about 0.2 to 0.8 mm as shown by a two-dot chain line in FIG. As shown in FIG. 5, the inner peripheral end 29 is bent in a direction away from the rear exhaust introduction wall 51 and is fitted to the cylindrical surface 36b so as to be densely movable. It has a frustoconical shape whose diameter is increased toward the exhaust introduction wall 51, and a curved portion 33 formed at the outer peripheral end 31 comes into contact with the rear surface of the rear exhaust introduction wall 51.

  The disc spring seal 37 installed by being fitted to the cylindrical surface 36b of the stepped portion 36 in FIG. 5 is formed by the pressure of the exhaust gas in the scroll passage 8 (the differential pressure between the pressure of the scroll passage 8 and the pressure of the gap 19). The curved portion 33 of the outer peripheral end 31 is automatically pressed against the rear surface of the rear exhaust introduction wall 51. At this time, the disc spring seal 37 is preliminarily formed so that the diameter thereof is reduced and the notched portion 38 shown in FIG. Also in the embodiment of FIG. 5, the sealing device 25 by the disc spring seal 37 can prevent the problem that the exhaust gas in the scroll passage 8 gas leaks through the gap 19 between the turbine housing 1 and the rear exhaust introduction wall 51.

  Also in the embodiment of FIG. 5, the front exhaust introduction wall 10 and the rear exhaust introduction wall 51 constituting the exhaust nozzle 9 have a simple disc-shaped configuration, so that the disc-shaped front portion The exhaust introduction wall 10 and the rear exhaust introduction wall 51 can be freely deformed only in the radial direction, and deformation in a direction other than the radial direction is suppressed, so that an unreasonable force acts on the nozzle vane 15. Therefore, the nozzle vane 15 can ensure a stable rotational operation.

  In addition, this invention is not limited only to the said form, Of course, a various change can be added in the range which does not deviate from the summary of this invention.

  According to the variable capacity turbocharger of the present invention, each of the front exhaust introduction wall and the rear exhaust introduction wall is formed into a disc shape, and the step portion in which the disc-shaped rear exhaust introduction wall is fitted with a gap is disposed in the turbine. By providing the housing, it is possible to suppress the deformation of the exhaust nozzle and to smoothly operate the nozzle vane.

DESCRIPTION OF SYMBOLS 1 Turbine housing 3 Bearing housing 4 Turbine impeller 8 Scroll path 9 Exhaust nozzle 10 Front exhaust introduction wall 11 'Disc-shaped rear exhaust introduction wall 15 Nozzle vane 16a, 16b Vane shaft 19 Clearance 21 Sealing piston ring 24 Through hole 25 Seal Device 28 Disc spring seal 50 Step

Claims (4)

  There is a gap between the rear exhaust introduction wall of the exhaust nozzle that holds the nozzle vane between the front exhaust introduction wall and the rear exhaust introduction wall and the turbine housing, and the exhaust gas in the scroll passage leaks to the turbine impeller side through the gap In order to prevent this, a turbocharger in which a sealing device is installed on the upstream side of the exhaust gas from the position of the through hole for penetrating the vane shaft provided in the rear exhaust introduction wall, the front exhaust introduction Each of the wall and the rear exhaust introduction wall has a disc shape, and the turbine housing includes a stepped portion in which the disc-shaped rear exhaust introduction wall is fitted with the gap.   The variable capacity turbocharger according to claim 1, wherein the front exhaust introduction wall and the rear exhaust introduction wall have the same linear expansion coefficient.   The variable capacity turbocharger according to claim 1, wherein the sealing device is a sealing piston ring.   The variable capacity turbocharger according to claim 1, wherein the sealing device is a disc spring seal.

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