JP2018053800A - Turbocharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a turbocharger capable of preventing vane stick without adding a member for preventing the vane stick.SOLUTION: A turbocharger 10 includes a turbine wheel, a plurality of variable nozzle vanes 30 provided turnably around turning shafts for regulating the flow rate of exhaust gas to the turbine wheel, an annular nozzle plate 26 turnably supporting the turning shafts of the plurality of variable nozzle vanes, and an annular shroud plate 40 arranged sandwiching the variable nozzle vanes 30 together with the nozzle plate 26, the nozzle plate 26 having a nozzle plate face 48 opposed to the variable nozzle vanes 30 and including cutting surfaces 49 each of which has concentric circular-arc cutting scars B1 around a shaft center Q of the turning shaft.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a turbocharger, and more particularly to a turbocharger having a variable nozzle mechanism.

  Conventional turbochargers may include a compressor driven by a turbine wheel and a plurality of variable nozzle vanes that adjust the flow rate of exhaust gas to the turbine wheel. The variable nozzle vane is disposed so as to be sandwiched between the annular first plate and the second plate, and is provided so as to be rotatable about a rotation shaft. A vane drive mechanism that rotates the variable nozzle vane is connected to the rotation shaft. A slight clearance is provided between the first plate and the variable nozzle vane and between the second plate and the variable nozzle vane. Further, the rotation shaft is inserted through a through hole provided in the first plate, but a slight clearance is provided between the rotation shaft and the first plate in the through hole.

  Incidentally, the first plate may be manufactured by cutting using a lathe or a milling machine. In this case, the first plate surface facing the variable nozzle vane in the first plate is a cutting surface processed by cutting, and has a large number of concentric cutting marks centering on the center of the first plate. Therefore, the rotation trajectory of the variable nozzle vane intersects with these cutting marks and is approximately orthogonal to these cutting marks. However, these concentric cutting traces become a resistance when the variable nozzle vane rotates, thereby making it difficult to prevent the rotation, and in a state where the turbocharger operates under high temperature non-lubrication, the generation of the vane stick is promoted. The vane stick refers to a state in which the variable nozzle vane cannot rotate when it hits at least one of the first plate and the second plate. In particular, when the vicinity of the front edge (upstream end) of the variable nozzle vane comes into contact with the first plate, the possibility of occurrence of a vane stick is high.

  As a conventional technique for solving a vane stick in a turbocharger, for example, a variable turbine nozzle supercharger disclosed in Patent Document 1 is known. A modified turbine nozzle type turbocharger disclosed in Patent Document 1 is a variable turbine comprising a compressor driven by an exhaust turbine and a row of vanes upstream of the exhaust turbine and pivotally supported on a substrate so as to be tiltable. Has a nozzle. Ceramic members are affixed to the substrate surface and the casing inner surface that are opposed to the base end surface and the free end surface of the vane. According to the variable turbine nozzle supercharger disclosed in Patent Document 1, there is no seizing or galling between the side end surface of the vane and the substrate or the casing, and smooth operation of the vane is always possible. It is said.

Microfilm of Japanese Utility Model No. 60-77286 (Japanese Utility Model Application No. 61-192523)

  However, in the variable turbine nozzle supercharger disclosed in Patent Document 1, ceramic members are pasted on the substrate surface and the casing inner surface, while preventing the occurrence of seizure or galling between the side end surface of the vane and the substrate or casing. There is a need to. The sticking of a ceramic member to a metal substrate or casing requires high-precision processing of the casing and production of a precise ceramic member, and the number of parts increases, leading to an increase in production cost.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a turbocharger capable of preventing a vane stick without adding a member for preventing the vane stick. .

  In order to solve the above-described problems, the present invention provides a turbine wheel, a plurality of variable nozzle vanes that are provided so as to be rotatable about a rotation shaft, and that adjust a flow rate of exhaust gas to the turbine wheel; A turbocharger comprising: an annular first plate that rotatably supports a rotating shaft of the variable nozzle vane; and an annular second plate disposed so as to sandwich the variable nozzle vane together with the first plate. The first plate surface of the first plate facing the variable nozzle vane includes a first cutting surface having a concentric arc-shaped cutting mark centered on the axis of the rotating shaft.

  In this invention, about the 1st cutting surface provided around the rotation axis of each variable nozzle vane in the 1st plate, the direction where the cutting trace extends is made to correspond with the rotation locus of a variable nozzle vane. For this reason, the concentric arc-shaped cutting trace centered on the axis of the turbine wheel formed on the first plate does not hinder the rotation of each variable nozzle vane and is variable with the first plate without adding parts. It is possible to prevent the occurrence of a vane stick between the nozzle vane.

In the above turbocharger, the first plate surface is adjacent to the first cutting surface and includes at least a movable range of the variable nozzle vane, and a rotation locus of the downstream end portion of the variable nozzle vane. The structure provided with the 2nd cutting surface which has the concentric arc-shaped cutting trace which approximates may be sufficient.
A turbine wheel shaft formed on the first plate by providing a second cutting surface adjacent to the first cutting surface with a concentric arc-shaped cutting trace that approximates the rotational trajectory of the downstream end of the variable nozzle vane. The concentric arc-shaped cutting trace centered on the center does not hinder the rotation of the downstream end of the variable nozzle vane, and more effectively prevents the occurrence of a vane stick between the first plate and the variable nozzle vane. be able to.

In the turbocharger described above, the second plate surface of the second plate facing the variable nozzle vane includes a third cutting surface having a concentric arc-shaped cutting mark around the axis of the rotating shaft. Also good.
In this case, even if the second plate is manufactured by cutting, the rotation trajectory of the variable nozzle vane matches the direction in which the cutting traces of the third cutting surface extend. For this reason, the cutting trace of the second plate does not hinder the rotation of the variable nozzle vane, and the generation of a vane stick between the second plate and the variable nozzle vane can be prevented without adding any parts.

  ADVANTAGE OF THE INVENTION According to this invention, the turbocharger which can prevent a vane stick can be provided, without adding the member for preventing a vane stick.

It is a longitudinal section showing a schematic structure of a turbocharger concerning a 1st embodiment. It is a rear view of the variable nozzle vane drive mechanism in a turbocharger. It is the front of the variable nozzle vane in a turbocharger. It is an expanded vertical sectional view of the principal part of a turbocharger. (A) is a front view which expands and shows a variable nozzle vane, (b) is a front view which expands and shows the principal part of a nozzle plate. (A) is a front view which expands and shows the variable nozzle vane of the turbocharger which concerns on 2nd Embodiment, (b) is a front view which expands and shows the principal part of a nozzle plate. (A) is a front view which expands and shows the variable nozzle vane of the turbocharger which concerns on the modification of 1st Embodiment, (b) is a front view which expands and shows the principal part of a nozzle plate.

(First embodiment)
The turbocharger according to the first embodiment will be described below with reference to the drawings. The turbocharger of the present embodiment is an in-vehicle turbocharger that is mounted on a vehicle. This vehicle is equipped with an internal combustion engine. An internal combustion engine burns a mixture of air supplied to a combustion chamber through an air supply passage and fuel supplied to the combustion chamber. The turbocharger of this embodiment is provided in this internal combustion engine. In this embodiment, for convenience of explanation, the right side in FIG. 1 is set as one side, and the left side is set as the other side.

  As shown in FIG. 1, the turbocharger 10 includes a bearing housing 11 located at the center of the turbocharger 10 and a turbine 12 provided on one side of the bearing housing 11. A compressor (not shown) is provided on the other side of the bearing housing 11. The bearing housing 11 accommodates a bearing 13 that rotatably supports the turbine shaft 14. One end of the turbine shaft 14 reaches the turbine, and the other end of the turbine shaft 14 reaches the compressor. The axis P of the turbine shaft 14 extends in the left-right direction in FIG.

  A turbine housing 15 is joined to one side of the bearing housing 11. The turbine housing 15 forms an outline of the turbine 12. A cylindrical turbine chamber 16 extending in the direction of the axis P is formed at the center of the turbine housing 15. A turbine wheel 17 that rotates in the turbine chamber 16 is fixed to one end of the turbine shaft 14. A compressor wheel (not shown) that rotates in the compressor housing is fixed to the other end of the turbine shaft 14. The turbine housing 15 and the compressor housing are fastened and fixed to the bearing housing 11 by bolts. The bearing housing 11, the turbine housing 15 and the compressor housing constitute a housing for the turbocharger 10.

  As shown in FIG. 1, the turbine wheel 17 includes a turbine hub portion 18 fixed to one end of the turbine shaft 14. The outer peripheral surface of the turbine hub portion 18 extends radially outward from the rear surface of the turbine wheel 17 toward the front surface. A plurality of turbine blades 19 are provided on the outer peripheral surface of the turbine hub portion 18 at intervals in the circumferential direction.

  A spiral scroll passage 20 is formed around the turbine chamber 16 in the turbine housing 15. The scroll passage 20 is formed with a gas intake (not shown) that serves as an exhaust gas inlet. This gas intake is connected to an exhaust manifold (not shown) of the internal combustion engine. The turbine housing 15 is formed with a gas discharge port 21 for discharging exhaust gas. The gas discharge port 21 is an exhaust gas outlet, communicates with the scroll passage 20 and is connected to an exhaust pipe (not shown). The turbine 12 is interposed in the exhaust passage of the internal combustion engine.

  The scroll passage 20 is formed outside the turbine chamber 16 in the radial direction of the turbine shaft 14. The turbine chamber 16 and the scroll passage 20 communicate with each other via a communication passage 22. The turbine housing 15 is integrally formed with a bulging portion 23 extending toward the bearing housing 11 side. The bulging portion 23 has an annular shape centered on the axis P, and constitutes a part of the inner wall surface of the turbine chamber 16.

  The turbocharger 10 includes a variable nozzle mechanism (variable nozzle mechanism) 25. The variable nozzle mechanism 25 changes the exhaust flow area of the communication passage 22 and makes the flow rate of the exhaust gas E sprayed to the turbine wheel 17 variable. The variable nozzle mechanism 25 adjusts the rotational speed of the turbocharger 10 by making the flow rate of the exhaust gas E variable, and adjusts the amount of air forcedly fed into the combustion chamber of the internal combustion engine.

  Next, a schematic configuration of the variable nozzle mechanism 25 will be described. As shown in FIGS. 2, 3, and 4, the variable nozzle mechanism 25 includes a nozzle plate 26 as a first plate and a unison ring 27. The nozzle plate 26 and the unison ring 27 have an annular shape with the axis P as the center.

  As shown in FIG. 4, a plurality of shaft holes 28 are formed in the nozzle plate 26. The plurality of shaft holes 28 are located on a circle centered on the axis P in the nozzle plate 26 and are arranged at equal angles. A pivot shaft 31 connected to the variable nozzle vane 30 is inserted into the shaft hole 28. The shaft center Q of the shaft hole 28 and the rotation shaft 31 is parallel to the shaft center P. The rotation shaft 31 is rotatable with respect to the nozzle plate 26. The tip of the rotation shaft 31 protrudes from the shaft hole 28 of the nozzle plate 26 and faces the bearing housing 11. The proximal end portion of the arm 32 is fixed to the distal end portion of the rotating shaft 31. A variable nozzle vane 30 is fixed to the base end portion of the rotating shaft 31.

  Concave portions 33 are provided at a plurality of locations on the inner peripheral surface of the unison ring 27. The tip portions of the arms 32 are engaged with these concave portions 33. The unison ring 27 is rotated by an actuator (not shown) provided outside the turbocharger 10 via the link 34. An arm 36 is fixed to a shaft 35 fixed to the link 34. The distal end portion of the arm 36 is engaged with a recess 37 provided on the inner peripheral surface of the unison ring 27. The nozzle plate 26 is provided with a pin 38 that contacts the side of the arm 36. When the unison ring 27 is rotated around the axis P via the link 34, the shaft 35, and the arm 36 by the operation of the actuator, each arm 32 engaged with the plurality of recesses 33 of the unison ring 27. Are rotated around the rotation shaft 31 in a synchronized state.

  With each rotation of the rotation shaft 31, the variable nozzle vane 30 rotates about the rotation shaft 31. The opening of the variable nozzle vane 30 is changed by the rotation of the variable nozzle vane 30, and the exhaust flow area in the communication path 22 is changed. Then, the flow rate of the exhaust gas E blown to the turbine wheel 17 through the adjacent variable nozzle vanes 30 is adjusted.

  In FIG. 2, when the arm 36 is rotated counterclockwise with the pin 38 as a fulcrum, the unison ring 27 rotates in the direction of the arrow. As the unison ring 27 rotates counterclockwise, the rotation shaft 31 rotates counterclockwise. The counterclockwise rotation of the rotation shaft 31 in FIG. 2 is the rotation of the rotation shaft 31 in the clockwise direction in FIG. The clockwise rotation of the rotation shaft 31 in FIG. 3 rotates toward the side where the variable nozzle vane 30 closes, and the flow rate of the exhaust gas E sprayed on the turbine wheel 17 increases. When the variable nozzle vane 30 rotates to the opening side, the flow velocity of the exhaust gas E blown to the turbine wheel 17 becomes lower than that when the variable nozzle vane 30 rotates to the closing side.

  The variable nozzle mechanism 25 includes an annular shroud plate 40 centered on the axis P. The nozzle plate 26 as the first plate and the shroud plate 40 as the second plate are arranged at a distance from each other in the direction of the axis Q of the rotation shaft 31. A variable nozzle vane 30 is located between the nozzle plate 26 and the shroud plate 40. That is, the nozzle plate 26 and the shroud plate 40 are disposed with the variable nozzle vane 30 interposed therebetween. The shroud plate 40 is provided at a position farther from the bearing housing 11 than the nozzle plate 26. In the present embodiment, the shroud plate 40 is formed by press molding.

  As shown in FIGS. 1 and 4, the variable nozzle vane 30 is provided with a shaft 41 that protrudes toward the shroud plate 40. The shaft 41 is coaxial with the rotation shaft 31. As shown in FIG. 4, a bottomed hole 42 into which a shaft 41 is inserted is provided in a shroud plate surface 39 of the shroud plate 40 that faces the variable nozzle vane 30. The shaft 41 is inserted into the bottomed hole 42. Therefore, the variable nozzle vane 30 is supported by the nozzle plate 26 and the shroud plate 40 by so-called “both ends” by the rotating shaft 31 and the shaft 41. A plurality of spacer members 43 are provided between the nozzle plate and the shroud plate 40. The spacer member 43 defines a distance from the shroud plate 40. The spacer member 43 is provided at a position where it does not interfere with the variable nozzle vane 30.

  A shielding member 45 and a disc spring 46 are provided between the shroud plate 40 and the bulging portion 23 of the turbine housing 15. The shielding member 45 is disposed around the turbine wheel 17 and abuts on the vicinity of the outer periphery of the shroud plate 40 and the tip surface of the bulging portion 23. The shroud plate 40 and the shielding member 45 form a space 47 that is isolated from the scroll passage. The disc spring 46 is provided in the space 47 and contacts the shroud plate 40 and the shielding member 45 in the axial center P direction. The biasing force of the disc spring 46 presses the shroud plate 40 toward the nozzle plate 26.

  Here, the movable range of the variable nozzle vane 30 will be described. In FIG. 5A, the variable nozzle vane 30 indicated by a solid line is in a state where the communication passage 22 is opened to the maximum, and the variable nozzle vane 30 indicated by a two-dot chain line is in a state where the communication passage 22 is most closed. In FIG. 5B, the movable range S of the variable nozzle vane 30 is shown with the variable nozzle vane 30 removed from the nozzle plate 26. The movable range S is a region surrounded by a two-dot chain line.

  The nozzle plate 26 of the present embodiment is manufactured well for cutting using a lathe and a milling machine. Assuming that the surface of the nozzle plate 26 facing the variable nozzle vane 30 is a nozzle plate surface 48, the nozzle plate surface 48 satisfies the machining roughness (micron order) required by design, but a plurality of cutting traces by cutting. A exists. The plurality of cutting marks A are concentric circular or concentric arc-shaped fine grooves centering on an axis P formed by a cutting blade included in the tool. The plurality of cutting marks A form fine irregularities in the radial direction of the nozzle plate surface 48.

  The rotation trajectory of the variable nozzle vane 30 intersects the plurality of cutting marks A, and is approximately orthogonal to the cutting marks A. The concentric cutting mark A becomes a resistance when the variable nozzle vane 30 is rotated, and the rotation is easily prevented. Therefore, in the present embodiment, a circular cutting surface 49 centering on the axis Q is formed on the nozzle plate surface 48. The cutting surface 49 corresponds to a first cutting surface. On the cutting surface 49, there are a plurality of cutting marks B1 that satisfy the machining roughness (micron order) required in the design. The cutting mark B1 is a concentric or concentric arc-shaped fine groove centered on the axis Q. The cutting surface 49 having a plurality of cutting marks B1 is formed by cutting using a milling machine. The cutting mark B1 is formed by pressing a rotating cutting blade (not shown) corresponding to the area of the cutting surface 49 against the nozzle plate surface 48, or revolving the cutting blade rotating around the shaft hole 28. May be formed. The center of the cutting trace B1 and the center of the rotation trajectory of the variable nozzle vane 30 coincide with the axis Q, and the cutting trace B1 follows the rotation trajectory of the variable nozzle vane 30. That is, the cutting mark B1 coincides with the turning locus of the variable nozzle vane 30.

  In the variable nozzle vane 30 of the present embodiment, the length from the axis Q to the front edge (upstream end) LE of the variable nozzle vane 30 is longer than the length from the axis Q to the rear edge (downstream end) TE of the variable nozzle vane 30. short. The radius of the cutting surface 49 coincides with the length from the axis Q to the front edge (upstream end) LE of the variable nozzle vane 30. Therefore, as shown in FIG. 5B, the vicinity of the trailing edge (downstream end) TE of the variable nozzle vane 30 protrudes from the cutting surface 49. Incidentally, if the cutting surface having a radius from the axis Q to the trailing edge (downstream end) TE of the variable nozzle vane 30 is a radius, this cutting surface overlaps the cutting surface of the adjacent variable nozzle vane 30. In this case, the cutting marks B1 intersect with each other at the portions where the cutting surfaces overlap each other. For this reason, in this embodiment, the radius of the cutting surface 49 is made equal to the length from the axis Q to the front edge (upstream end) LE of the variable nozzle vane 30. Note that the radius of the cutting surface 49 may be slightly longer or slightly shorter than the length from the axis Q to the front edge (upstream end) LE of the variable nozzle vane 30. In order to reliably prevent the vane stick at the edge (upstream end) LE, it is preferable that the radius of the cutting surface 49 is equal to or longer than the length from the axis Q to the front edge (upstream end) LE of the variable nozzle vane 30.

  Next, the operation of the turbocharger 10 according to this embodiment will be described. Exhaust gas E discharged as the internal combustion engine operates flows into the turbocharger 10 in the process of flowing through the exhaust passage. The exhaust gas E that has flowed in flows along the scroll passage 20 of the turbine housing 15. The exhaust gas E flowing through the scroll passage 20 passes through the communication passage 22, but passes between the adjacent variable nozzle vanes 30 when passing through the communication passage 22. The exhaust gas E that has passed through the communication passage 22 is blown to the turbine wheel 17 in the turbine chamber 16.

  When the exhaust gas E is blown onto the turbine wheel 17, the turbine wheel 17 is rotationally driven. By rotating the turbine wheel 17, the compressor wheel coaxial with the turbine wheel 17 rotates integrally with the turbine wheel 17. As a result, in the internal combustion engine, the air sucked by the negative pressure generated in the combustion chamber as the piston moves is forcibly sent to the combustion chamber by the rotation of the compressor wheel of the turbocharger 10. That is, the charging efficiency of air into the combustion chamber is increased by supercharging the air into the combustion chamber.

  When the variable nozzle vane 30 is rotated from the outside of the turbocharger 10 through the operation of the link 34 or the like, the opening degree of the variable nozzle vane 30 is changed. By changing the opening degree of the variable nozzle vane 30, the flow rate of the exhaust gas E sprayed on the turbine wheel 17 is changed. As a result, the rotational speed of the turbocharger 10 is changed, and the supercharging pressure of the internal combustion engine is adjusted.

  By the way, when the opening degree of the variable nozzle vane 30 is changed, the rotation locus of the variable nozzle vane 30 draws an arc centered on the axis Q. As shown in FIG. 5A, the cutting surface 49 of the nozzle plate surface 48 has a cutting mark B1 that is a concentric or concentric arc-shaped fine groove centered on the axis Q. The plurality of cutting marks B1 coincides with the turning locus of the variable nozzle vane 30. For this reason, the variable nozzle vane 30 is displaced along the cutting mark B1 when rotating, and the variable nozzle vane 30 rotates smoothly. The displacement at which the variable nozzle vane 30 crosses the cutting mark A is slight, and the cutting of the variable nozzle vane 30 by the cutting mark A is hardly hindered. In particular, even if the vicinity of the front edge (upstream end) LE of the variable nozzle vane 30 comes into contact with the nozzle plate 26, the rotation by the cutting mark A is not hindered, and the vane stick is prevented.

The turbocharger according to the above embodiment has the following operational effects.
(1) With respect to the cutting surface 49 which is the first cutting surface provided around the rotation shaft 31 of each variable nozzle vane 30 in the nozzle plate 26, the direction in which the cutting mark B1 extends coincides with the rotation locus of the variable nozzle vane 30. ing. For this reason, the concentric arc-shaped cutting mark A formed on the nozzle plate 26 around the axis P of the turbine wheel 17 does not hinder the rotation of each variable nozzle vane 30, and the nozzle can be added without adding parts. Generation of a vane stick between the plate 26 and the variable nozzle vane 30 can be prevented.

(2) Of the movable range S of the variable nozzle vane 30, most of the range centering on the axis Q of the rotating shaft is occupied by the cutting surface 49 having the cutting mark B <b> 1. In particular, the vicinity of the front edge (upstream end) LE of the variable nozzle vane 30 faces the cutting mark B1. For this reason, even if the vicinity of the front edge (upstream end) LE of the variable nozzle vane 30 comes into contact with the nozzle plate 26, the influence of the cutting trace A can be reduced.

(3) The radius of the cutting surface 49 coincides with the length from the axis Q to the front edge (upstream end) LE of the variable nozzle vane 30. Accordingly, the vicinity of the trailing edge (downstream end) TE of the variable nozzle vane 30 protrudes from the cutting surface 49, but the cutting surface 49 does not overlap with the cutting surface 49 of the adjacent variable nozzle vane 30. Therefore, the surfaces where the cutting marks B1 intersect with each other are not formed, and the surfaces where the cutting marks B1 intersect with each other do not hinder the rotation of the variable nozzle vane 30.

(Second Embodiment)
Next, a turbocharger according to the second embodiment will be described. The second embodiment is different from the first embodiment in that the cutting mark A does not exist in almost the entire movable range of the variable nozzle vane. In the present embodiment, for the same configuration as the first embodiment, the description of the first embodiment is used, and common reference numerals are used.

  As shown in FIGS. 6A and 6B, in the turbocharger 50 of the present embodiment, a circular cutting surface 49 centering on the axis Q is formed on the nozzle plate surface 48, and cutting is performed. Apart from the surface 49, a substantially crescent-shaped cutting surface 51 is formed. The cutting surface 51 is formed so as to include a range outside the cutting surface 49 in the movable range S. The cutting surface 51 corresponds to a second cutting surface. On the cutting surface 51, there are a plurality of cutting marks B2 that satisfy the machining roughness (micron order) required in design.

  The cutting mark B2 is a concentric arc-shaped fine groove centered on the axis R. The shaft center R is a position away from the shaft center Q, and is located downstream of the shaft hole 28 in the movable range S. The cutting surface 51 having a plurality of cutting marks B2 is formed by cutting using a milling machine. A crescent-shaped cutting surface 51 is formed by forming the cutting surface 49 after cutting in a circle around the axis R. The cutting mark B2 is formed by pressing a rotating cutting blade (not shown) corresponding to the area of the cutting surface 51 against the nozzle plate surface 48. Alternatively, the cutting mark B2 revolves around the shaft hole 28. May be formed. The axis R that is the center of the cutting mark B2 does not coincide with the axis Q that is the center of the turning locus of the variable nozzle vane 30, but the cutting mark B2 is substantially along the turning locus of the variable nozzle vane 30. That is, the direction in which the cutting mark B <b> 2 extends approximates the rotation trajectory of the variable nozzle vane 30. The radius of the cutting surface 51 is substantially the same as the radius of the cutting surface 49.

  By the way, the rotating shaft 31 of the variable nozzle vane 30 is provided at a position near the front edge LE of the variable nozzle vane 30. When it is attempted to cover the movable range S of the variable nozzle vane 30 only with the cutting surface 49 centered on the axis Q of the rotating shaft 31, the radius of the cutting surface 49 becomes large, and the variable nozzle vane 30 with the cutting surface 49 positioned next to it. Interference with the movable range S. On the other hand, when the radius of the cutting surface 49 is set so as not to interfere with the movable range S of the variable nozzle vane 30 located next to the cutting surface 49, the first implementation is performed in a range corresponding to the vicinity of the trailing edge TE of the variable nozzle vane 30 in the movable range S. The cutting mark A will remain as in the form. By providing the cutting surface 49 around the rotating shaft, the influence of the cutting mark A remaining in the range corresponding to the vicinity of the rear edge TE of the variable nozzle vane 30 on the rotating variable nozzle vane 30 can be sufficiently reduced. Since the extending direction of A and the rotation trajectory of the variable nozzle vane 30 are in a state of crossing each other, a slight vane stick may occur. Therefore, in the present embodiment, a cutting surface 51 having a concentric arc-shaped cutting mark B2 that approximates the rotation trajectory of the downstream end of the variable nozzle vane 30 is formed next to the cutting surface 49.

  According to the present embodiment, in addition to the operational effects equivalent to the operational effects of the first embodiment, it is possible to suppress the vane stick between the downstream end of the variable nozzle vane 30 and the nozzle plate 26 due to the cutting marks A. it can. That is, the occurrence of a vane stick between the nozzle plate 26 and the variable nozzle vane 30 can be reliably prevented.

  The above embodiment shows an embodiment of the present invention, and the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the invention as described below. Is possible.

As a modification of the first embodiment, for example, as shown in FIG. 7, the range of the cutting surface 49 by the cutting mark B <b> 1 may be enlarged to reach the trailing edge TE of the variable nozzle vane 30. In this modification, first, the first cutting surface 49 centering on the axis Q of the variable nozzle vane 30 is formed. Next, the 2nd cutting surface 49 centering on the axial center Q of the adjacent variable nozzle vane 30 used as the upstream of the 1st cutting surface 49 is formed. For this reason, the cutting surface 49 formed first lacks a part on the upstream side due to the formation of the cutting surface 49 formed second. Then, the cutting surface 49 is formed in order for each variable nozzle vane 30 toward the upstream side. Thereby, the cutting surface 49 which a part of upstream side lacked is formed in order. However, a part of the upstream side of the cutting surface 49 formed last is not missing. In addition, the cutting surface 49 formed first is not only partially cut off on the upstream side, but also part of the downstream side is cut off by the cutting surface 49 formed last. Therefore, the vicinity of the trailing edge TE of the variable nozzle vane 30 corresponding to the cutting surface 49 formed first is displaced with respect to the cutting mark B1 of the cutting surface 49 formed last on the downstream side. According to this modification, the same operational effects as those of the first embodiment can be obtained.

In the above embodiment, the shroud plate that is the second plate is formed by press molding, but the second plate may be manufactured by cutting. When the second plate is manufactured by cutting, the second plate surface facing the variable nozzle vanes of the two plates is provided with a third cutting surface having a concentric arc-shaped cutting mark around the axis of the rotation shaft. That's fine. The third cutting surface has the same configuration as the first cutting surface. In this case, even if the second plate is manufactured by cutting, the turning trajectory of the variable nozzle vane matches the cutting trace on the third cutting surface. For this reason, the cutting trace does not hinder the rotation of the variable nozzle vane, and the generation of the vane stick caused by the cutting trace of the second plate can be prevented. Furthermore, a fourth cutting surface having a concentric arc-shaped cutting trace that approximates the rotation trajectory of the downstream end of the variable nozzle vane may be provided on the second plate. The fourth cutting surface corresponds to the second cutting surface.
In the second embodiment, since the first cutting surface is circular and the second cutting surface is a crescent, the concentric or concentric arc-shaped cutting marks other than the movable range of the variable nozzle vane on the first plate surface However, this is not the case. For example, the first cutting surface may be formed so that concentric arc-shaped cutting traces exist only in the movable range of the variable nozzle vane.
In the above-described embodiment, the variable nozzle vane is supported by “both ends” on the first plate and the second plate, but this is not restrictive. For example, the variable nozzle vane may have a “cantilever” structure that is supported on the first plate by a rotating shaft.

10, 50 Turbocharger 11 Bearing housing 12 Turbine 15 Turbine housing 16 Turbine chamber 17 Turbine wheel 20 Scroll passage 22 Communication passage 25 Variable nozzle mechanism 26 Nozzle plate (first plate)
27 Unison ring 28 Shaft hole 30 Variable nozzle vane 31 Rotating shaft 32 Arm 34 Link 40 Shroud plate (second plate)
47 Nozzle plate surface 48 Cutting surface (first cutting surface)
51 Cutting surface (second cutting surface)
A, B1, B2 Cutting marks P, Q, R Axis center E Exhaust gas S Movable range LE Front edge TE Rear edge

Claims (3)

A turbine wheel,
A plurality of variable nozzle vanes provided so as to be rotatable about a rotation axis and adjusting a flow rate of exhaust gas to the turbine wheel;
An annular first plate that rotatably supports the rotation shafts of the plurality of variable nozzle vanes;
In a turbocharger comprising: an annular second plate disposed so as to sandwich the variable nozzle vane together with the first plate;
The turbocharger, wherein a first plate surface of the first plate facing the variable nozzle vane includes a first cutting surface having a concentric arc-shaped cutting mark centered on an axis of the rotating shaft.   The first plate surface has a concentric arc-shaped cutting trace that approximates the rotation trajectory of the downstream end of the variable nozzle vane in a region adjacent to the first cutting surface and including at least the movable range of the variable nozzle vane. The turbocharger according to claim 1, further comprising a second cutting surface.   The second plate surface of the second plate facing the variable nozzle vane includes a third cutting surface having a concentric arc-shaped cutting mark centering on the axis of the rotating shaft. The listed turbocharger.

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