turbocharger

Abstract

This supercharger comprises: turbine blades; a turbine housing including a flow path through which there flows a gas received from a flow inlet; a variable-capacity mechanism disposed in the turbine housing, the variable-capacity mechanism receiving the gas from the flow path and guiding the received gas to the turbine blades; and a disc spring that applies, to the variable-capacity mechanism, a biasing force for pressing the variable-capacity mechanism toward the turbine housing. The turbine housing has a turbine housing flange reverse surface that contacts the variable-capacity mechanism along the rotation-axis direction of the turbine blades. The variable-capacity mechanism has a nozzle-ring-outer-side flange main surface that contacts the turbine housing flange reverse surface along the rotation-axis direction. The turbine housing flange reverse surface and / or the nozzle-ring-outer-side flange main surface is machined to improve the coefficient of friction thereof.

Description

[Technical Field]

[0001] The present disclosure relates to a supercharger. [Background technology]

[0002] Patent Document 1 discloses a variable displacement turbocharger. The variable displacement turbocharger is equipped with a variable displacement mechanism. The variable displacement mechanism changes the gas flow path area using multiple nozzle vanes. As a result, the flow velocity of the gas supplied to the turbine wheel is controlled. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2017 / 150450 Summary of the Invention [Problem to be solved by the invention]

[0004] Among the multiple components that make up the turbocharger, those that are not intended to be driven are fixed so that they do not move relative to one another. However, when the turbocharger is in operation, the degree of fixation may loosen due to the influence of thermal deformation of the components, etc. If the degree of fixation loosens, external forces acting from the outside may cause the components to move slightly relative to one another.

[0005] The present disclosure describes a supercharger that can suppress the occurrence of relative micro-movement between parts. [Means for solving the problem]

[0006] A turbocharger according to one embodiment of the present disclosure includes a turbine wheel, a first housing including a flow path through which gas received from an inlet flows, a variable displacement mechanism disposed in the first housing and receiving gas from the flow path and directing it to the turbine wheel, and a biasing member applying a biasing force to the variable displacement mechanism to press the variable displacement mechanism against the first housing. The first housing has a first housing abutment surface that contacts the variable displacement mechanism along the direction of the rotational axis of the turbine wheel. The variable displacement mechanism has a first variable displacement mechanism abutment surface that contacts the first housing abutment surface along the direction of the rotational axis. At least one of the first housing abutment surface and the first variable displacement mechanism abutment surface is treated to increase the coefficient of friction. [Effects of the Invention]

[0007] The turbocharger of the present disclosure can suppress the occurrence of relative micro-movement between parts. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view showing a turbocharger according to an embodiment. [Figure 2] FIG. 2 is a perspective view showing the variable capacity mechanism shown in FIG. [Figure 3] FIG. 3 is an enlarged view of a portion where the turbine housing and the variable capacity mechanism shown in FIG. 1 come into contact with each other. [Figure 4] FIG. 4 is an enlarged view of the main parts of the heat shield plate, the variable capacity mechanism, and the bearing housing shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] A turbocharger according to one embodiment of the present disclosure includes a turbine wheel, a first housing including a flow path through which gas received from an inlet flows, a variable displacement mechanism disposed in the first housing and receiving gas from the flow path and directing it to the turbine wheel, and a biasing member applying a biasing force to the variable displacement mechanism to press the variable displacement mechanism against the first housing. The first housing has a first housing abutment surface that contacts the variable displacement mechanism along the direction of the rotational axis of the turbine wheel. The variable displacement mechanism has a first variable displacement mechanism abutment surface that contacts the first housing abutment surface along the direction of the rotational axis. At least one of the first housing abutment surface and the first variable displacement mechanism abutment surface is treated to increase the coefficient of friction.

[0010] At the contact point between the first housing and the variable displacement mechanism, a frictional force is generated according to the biasing force generated by the biasing member and the friction coefficient. At least one of the first housing contact surface and the first variable displacement mechanism contact surface is processed to increase the friction coefficient. This makes it possible to increase the frictional force determined by the product of the friction coefficient and the biasing force. The frictional force can suppress the occurrence of relative micro-movements between the first housing and the variable displacement mechanism. This makes it possible to suppress the occurrence of relative micro-movements between the components.

[0011] The turbocharger further includes a second housing that rotatably supports the rotating shaft to which the turbine wheel is fixed, and an annular intermediate member that is disposed between the first housing and the variable displacement mechanism. The variable displacement mechanism has a first arrangement hole through which the turbine wheel or the rotating shaft is inserted, and a second variable displacement mechanism abutment surface that surrounds the first arrangement hole. The intermediate member has a first intermediate member abutment surface that abuts on the second variable displacement mechanism abutment surface. At least one of the second variable displacement mechanism abutment surface and the first intermediate member abutment surface may be processed to increase the coefficient of friction. This configuration can suppress relative micromotion between the variable displacement mechanism and the intermediate member.

[0012] The turbocharger further includes a second housing that rotatably supports a rotary shaft to which a turbine wheel is fixed, and an annular intermediate member disposed between the first housing and the variable displacement mechanism. The intermediate member has a second intermediate member abutment surface that faces the second housing and with which the biasing member contacts. The biasing member has a first biasing member abutment surface that contacts the second intermediate member abutment surface. At least one of the second intermediate member abutment surface and the first biasing member abutment surface may be processed to increase the coefficient of friction. This configuration can suppress relative micromotion between the biasing member and the intermediate member.

[0013] The turbocharger further includes a second housing that rotatably supports a rotating shaft to which the turbine wheel is fixed. The second housing has a second housing abutment surface that contacts the biasing member along the direction of the rotation axis. The biasing member has a second biasing member abutment surface that contacts the second housing abutment surface. At least one of the second housing abutment surface and the second biasing member abutment surface may be processed to increase the coefficient of friction. This configuration can suppress relative micromotion between the biasing member and the second housing.

[0014] The above turbocharger further includes a second housing that rotatably supports the rotating shaft to which the turbine wheel is fixed. The variable displacement mechanism has a first arrangement hole through which the turbine wheel or the rotating shaft is inserted. The first arrangement hole includes a first arrangement hole inner circumferential surface portion in which a second housing shoulder of the second housing is disposed. The second housing shoulder portion has a second housing shoulder surface that contacts the first arrangement hole inner circumferential surface portion. At least one of the first arrangement hole inner circumferential surface portion and the second housing shoulder surface may be processed to increase the coefficient of friction. With this configuration, it is possible to suppress relative micromotion between the variable displacement mechanism and the second housing.

[0015] Another embodiment of the present disclosure provides a turbocharger comprising: a turbine wheel; a first housing including a flow path through which gas received from an inlet flows; a variable displacement mechanism disposed in the first housing and receiving the gas from the flow path and directing it to the turbine wheel, the variable displacement mechanism including a disk-shaped nozzle ring having a main surface facing the turbine wheel; and a plurality of nozzle vanes disposed on the main surface of the nozzle ring and forming a plurality of nozzle flow paths through which the gas is directed; and a biasing member applying a biasing force to the variable displacement mechanism to press the variable displacement mechanism against the first housing. The first housing has a first housing abutment surface that contacts the variable displacement mechanism along the direction of the rotational axis of the turbine wheel. The variable displacement mechanism has a first variable displacement mechanism abutment surface that contacts the first housing abutment surface along the rotational axis. The nozzle ring has a separation surface that is spaced from a first component separate from the nozzle ring and a sliding surface along which a second component separate from the nozzle ring slides. The surface roughness of at least one of the first housing abutment surface and the first variable displacement mechanism abutment surface is greater than the surface roughness of the separation surface.

[0016] At the contact point between the first housing and the variable displacement mechanism, a frictional force is generated according to the biasing force generated by the biasing member and the friction coefficient. The surface roughness of at least one of the first housing contact surface and the first variable displacement mechanism contact surface is greater than the surface roughness of the separation surface. This makes it possible to increase the frictional force, which is determined by the product of the friction coefficient (depending on the surface roughness) and the biasing force. This frictional force can suppress the occurrence of relative micro-motion between the first housing and the variable displacement mechanism. Therefore, the occurrence of relative micro-motion between the components can be suppressed.

[0017] In the turbocharger, the surface roughness of at least one of the first housing contact surface and the first variable displacement mechanism contact surface may be greater than the surface roughness of the sliding surface. This configuration also makes it possible to suppress relative micro-motion between the components.

[0018] In the turbocharger described above, the first component is the first housing. The separation surface may be an outer peripheral surface of the nozzle ring that faces the inner peripheral surface of the first housing and is spaced from the inner peripheral surface of the first housing. This configuration also makes it possible to suppress the occurrence of relative micromotion between the components.

[0019] In the turbocharger described above, the second component is a nozzle vane. The sliding surface may be a main surface of a nozzle ring on which the nozzle vanes slide. This configuration also makes it possible to suppress the occurrence of relative micromotion between the components.

[0020] Hereinafter, embodiments of the turbocharger of the present disclosure will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are given the same reference numerals, and duplicated explanations will be omitted.

[0021] The turbocharger 1 shown in FIG. 1 is a variable displacement turbocharger. The turbocharger 1 is applied to, for example, an internal combustion engine of a ship or a vehicle. The turbocharger 1 has a turbine 10 and a compressor 20. The turbine 10 has a turbine housing 11 (first housing), a turbine wheel 12, and a variable displacement mechanism 30. The turbine housing 11 has a scroll passage 13 (passage). The scroll passage 13 extends in the circumferential direction around the turbine wheel 12. The compressor 20 has a compressor housing 21 and a compressor wheel 22. The compressor wheel 22 is housed in the compressor housing 21. The compressor housing 21 has a scroll passage 23. The scroll passage 23 extends in the circumferential direction around the compressor wheel 22.

[0022] The turbine wheel 12 is provided at a first end of the rotating shaft 2. The compressor wheel 22 is provided at a second end of the rotating shaft 2. A bearing housing 3 (second housing) is provided between the turbine housing 11 and the compressor housing 21. The rotating shaft 2 is rotatably supported by the bearing housing 3 via a bearing 4. The rotating shaft 2, the turbine wheel 12, and the compressor wheel 22 form an integrated rotating body 5. The rotating body 5 rotates around a rotation axis AX.

[0023] The turbine housing 11 has an inlet 14s and an outlet 14r. Exhaust gas discharged from the internal combustion engine flows into the turbine housing 11 through the inlet 14s. The exhaust gas flows into the turbine wheel 12 through the scroll passage 13. The exhaust gas rotates the turbine wheel 12. The exhaust gas then flows out of the turbine housing 11 through the outlet 14r.

[0024] The compressor housing 21 has an intake port 24 and a discharge port. When the turbine wheel 12 rotates, the compressor wheel 22 rotates via the rotary shaft 2. The rotating compressor wheel 22 draws in external air through the intake port 24. The drawn air is compressed as it passes through the compressor wheel 22 and the scroll passage 23. The air is discharged from the discharge port as compressed air. The compressed air is supplied to the internal combustion engine.

[0025] The turbine 10 has a connecting passage S. The connecting passage S guides exhaust gas from the scroll passage 13 to the turbine wheel 12. A plurality of nozzle vanes 34 are arranged in the connecting passage S. The plurality of nozzle vanes 34 are arranged at equal intervals on a reference circle centered on the rotation axis AX. Adjacent nozzle vanes 34 form a nozzle. The nozzle vanes 34 rotate synchronously around an axis parallel to the rotation axis AX. The cross-sectional area of ​​the connecting passage S is adjusted by the rotation of the plurality of nozzle vanes 34. The turbine 10 has a variable capacity mechanism 30 as a mechanism for adjusting the cross-sectional area of ​​the connecting passage S. The variable capacity mechanism 30 is attached to the turbine housing 11.

[0026] <Variable capacity mechanism> As shown in FIGS. 1 and 2 , the variable displacement mechanism 30 includes a CC plate 31 (Clearance Control Plate), a nozzle ring 32, and multiple CC pins 33 (Clearance Control Pins). The nozzle ring 32 faces the CC plate 31. The CC pins 33 connect the CC plate 31 to the nozzle ring 32. A connecting flow path S is formed between the CC plate 31 and the nozzle ring 32. The variable displacement mechanism 30 also includes multiple nozzle vanes 34, a drive ring 35, multiple nozzle link plates 36, and a drive link plate 37. The nozzle link plate 36 and the drive link plate 37 are disposed on the opposite side of the nozzle ring 32 from the CC plate 31. The drive ring 35 and the drive link plate 37 cooperate to rotate the nozzle link plate 36. When the nozzle link plate 36 rotates, the nozzle vanes 34 rotate.

[0027] The CC plate 31 is shaped like a ring centered on the rotation axis AX. The CC plate 31 has an axial hole. The CC plate 31 circumferentially surrounds the turbine wheel 12 disposed in the axial hole 31h. The circumferential direction of the turbine wheel 12 is the direction centered on the rotation axis AX. The CC plate 31 is disposed between the scroll passage 13 and the outlet 14r. The CC plate 31 is spaced apart from the nozzle ring 32 along the rotation axis AX. A connection passage S is formed between the CC plate 31 and the nozzle ring 32. The connection passage S connects the scroll passage 13 to the outlet 14r. The CC plate 31 is disposed on the opposite side of the nozzle ring 32 from the bearing housing 3. The CC plate 31 has a plurality of pin holes 31p. The pin holes 31p are spaced equally apart in the circumferential direction.

[0028] The nozzle ring 32 is also ring-shaped and centered on the rotation axis AX. The nozzle ring 32 has a nozzle ring axial hole 32h. The nozzle ring 32 also circumferentially surrounds the turbine wheel 12 disposed in the nozzle ring axial hole 32h. The nozzle ring 32 is also disposed between the scroll passage 13 and the outlet 14r. The CC plate 31 is parallel to the nozzle ring 32. The nozzle ring 32 has a plurality of pin holes 32p. The pin holes 32p are spaced equally apart in the circumferential direction. The central axes of the pin holes 32p overlap with the central axis of the pin hole 31p. In other words, the pin hole 32p is coaxial with the pin hole 31p.

[0029] The nozzle ring 32 has a nozzle ring body 32a and a drive ring support portion 32b. The nozzle ring body 32a is cylindrical in shape. The nozzle ring body 32a has a nozzle ring shaft hole 32h. The nozzle ring body 32a has multiple vane shaft holes 32c. The multiple vane shaft holes 32c are equally spaced apart in the circumferential direction. The drive ring support portion 32b protrudes radially from the outer circumferential surface of the nozzle ring body 32a. The outer diameter of the nozzle ring 32 is determined by the outer diameter of the drive ring support portion 32b. The drive ring support portion 32b has multiple pin holes 32p. The pin holes 32p are located radially outward of the nozzle ring 32 relative to the vane shaft holes 32c.

[0030] The nozzle ring 32 is spaced apart from the CC plate 31. A gap is formed between the nozzle ring 32 and the CC plate 31. The gap is a connecting flow path S through which exhaust gas passes. The gap between the nozzle ring 32 and the CC plate 31 is maintained by a CC pin 33. A first end of the CC pin 33 is inserted into a pin hole 31p of the CC plate 31. A second end of the CC pin 33 is inserted into a pin hole 32p of the nozzle ring 32.

[0031] The multiple nozzle vanes 34 are arranged on a reference circle centered on the rotation axis AX. Each nozzle vane 34 has a vane body 34a and a vane shaft 34b. The vane body 34a is arranged between the CC plate 31 and the nozzle ring 32. The vane body 34a is arranged in the connecting flow passage S. A first end of the vane shaft 34b is fixed to the vane body 34a. A second end of the vane shaft 34b is inserted into a vane shaft hole 32c in the nozzle ring 32. A tip portion of the second end of the vane shaft 34b protrudes from the nozzle ring body 32a. The vane shaft 34b is rotatable relative to the nozzle ring 32. The vane body 34a rotates in conjunction with the rotation of the vane shaft 34b. In the variable displacement mechanism 30, the cross-sectional area of ​​the connecting flow passage S is adjusted by rotating the vane body 34a. As a result of adjusting the cross-sectional area, the flow velocity of the exhaust gas supplied from the scroll passage 13 to the turbine wheel 12 is controlled, and therefore the rotation speed of the turbine wheel 12 can be controlled to a desired value.

[0032] The drive ring 35 is disposed on the drive ring support portion 32b. The drive ring 35 is shaped like a ring centered on the rotation axis AX. The drive ring 35 has an axial hole 35h. The nozzle ring body 32a is inserted into the axial hole 35h. The drive ring 35 is coaxial with the nozzle ring 32. The drive ring 35 is rotatable relative to the nozzle ring 32 around the rotation axis AX. The drive ring 35 has a drive ring body 35a and a plurality of link plate arrangement portions 35b. The link plate arrangement portions 35b are spaced apart from one another in the circumferential direction. The link plate arrangement portions 35b have two upright members spaced apart from one another in the circumferential direction.

[0033] The nozzle link plate 36 is bar-shaped. A first end of the nozzle link plate 36 is fixed to an end of the vane shaft 34b. A second end of the nozzle link plate 36 is disposed in the link plate mounting portion 35b of the drive ring 35. The second end of the nozzle link plate 36 is disposed between two upright members of the link plate mounting portion 35b. When the drive ring 35 receives a driving force from the drive link plate 37, the drive ring 35 rotates about the rotation axis AX. This rotation causes the second end of the nozzle link plate 36 to move circumferentially in accordance with the rotation of the drive ring 35. As a result, the nozzle link plate 36 rotates about the vane shaft 34b. When the nozzle link plate 36 rotates, the vane shaft 34b attached to the first end of the nozzle link plate 36 rotates. The rotation of the vane shaft 34b rotates the vane bodies 34a attached to the first ends of the vane shafts 34b. As a result, the spacing between the vane bodies 34a changes. In other words, the cross-sectional area of ​​the connecting flow path S changes.

[0034] A heat shield 61 (intermediate member) is provided between the variable displacement mechanism 30 and the bearing housing 3. The heat shield 61 is disposed inside the nozzle ring axial hole 32h of the nozzle ring 32. The heat shield 61 is shaped like a ring centered on the rotation axis AX. The heat shield 61 prevents heat from transferring from the turbine housing 11 to the bearing housing 3. As a result, the temperature rise of the components disposed on the bearing housing 3 side is suppressed. A disc spring 62 (biasing member) is compressed and deformed in the axial direction by being sandwiched between the heat shield 61 and the bearing housing 3. The disc spring 62 exerts an elastic force that resists the compressive deformation. The disc spring 62 presses the heat shield 61 against the nozzle ring 32.

[0035] Figure 3 is an enlarged view of area S1 in Figure 1. Figure 3 shows an enlarged view of the portion where the variable capacity mechanism 30 contacts the turbine housing 11. The nozzle ring 32 of the variable capacity mechanism 30 has a nozzle ring outer flange 32f1 in addition to a nozzle ring main body 32a and a drive ring support portion 32b.

[0036] The nozzle ring outer flange 32f1 protrudes radially from the drive ring support portion outer peripheral surface 325 of the drive ring support portion 32b. The nozzle ring outer flange 32f1 has a nozzle ring outer flange outer peripheral surface 321, a nozzle ring outer flange main surface 322 (first variable capacity mechanism abutment surface), and a nozzle ring outer flange back surface 323.

[0037] The nozzle ring outer flange outer peripheral surface 321 faces the turbine housing inner peripheral surface 111. The nozzle ring outer flange outer peripheral surface 321 does not contact the turbine housing inner peripheral surface 111. A gap exists between the nozzle ring outer flange outer peripheral surface 321 and the turbine housing inner peripheral surface 111.

[0038] The nozzle ring outer flange main surface 322 faces the turbine housing flange back surface 112 (first housing abutment surface). The nozzle ring outer flange main surface 322 contacts the turbine housing flange back surface 112 of the turbine housing flange 11f. This contact determines the position of the variable displacement mechanism 30 along the rotation axis AX. More specifically, the nozzle ring outer flange main surface 322 is pressed against the turbine housing flange back surface 112.

[0039] More specifically, the nozzle ring outer flange main surface 322 includes an area that contacts the turbine housing flange back surface 112 and an area that does not contact the turbine housing flange back surface 112. The area that contacts the turbine housing flange back surface 112 is referred to as the flange main surface contact area 322a. The area that does not contact the turbine housing flange back surface 112 is referred to as the flange main surface non-contact area 322b.

[0040] Nozzle ring outer flange back surface 323 is flush with drive ring support portion back surface 324. Nozzle ring outer flange back surface 323 cooperates with drive ring support portion back surface 324 to form drive ring support surface 32d. Drive ring support surface 32d faces drive ring main surface 351. Drive ring support surface 32d is in contact with drive ring main surface 351. Drive ring support surface 32d slides relative to drive ring main surface 351 around rotation axis AX.

[0041] The drive ring support portion outer peripheral surface 325 is a cylindrical surface located between the nozzle ring outer flange main surface 322 and the nozzle ring main surface 32e. The drive ring support portion outer peripheral surface 325 faces the turbine housing flange inner peripheral surface 113. The drive ring support portion outer peripheral surface 325 does not contact the turbine housing flange inner peripheral surface 113. A gap exists between the drive ring support portion outer peripheral surface 325 and the turbine housing flange inner peripheral surface 113. This gap corresponds to the flange main surface non-contact region 322b described above.

[0042] As already mentioned, the nozzle ring outer flange main surface 322 is pressed against the turbine housing flange back surface 112. The force that presses the nozzle ring outer flange main surface 322 against the turbine housing flange back surface 112 is generated by the disc spring 62 (see FIG. 1 ). The force generated by the disc spring 62 generates a frictional force between the nozzle ring outer flange main surface 322 and the turbine housing flange back surface 112. This frictional force suppresses slight movement of the variable displacement mechanism 30 relative to the turbine housing 11.

[0043] The frictional force is determined by the product of the friction coefficient and the pressing force. The nozzle ring outer flange main surface 322 is subjected to a surface treatment to increase the friction coefficient. Examples of surface treatments that increase the friction coefficient include knurling and blasting.

[0044] In the case of processing such as knurling to provide minute irregularities on the surface, the irregularities may be formed so as to prevent the nozzle ring 32 from rotating about the rotation axis AX. For example, in the case of forming minute grooves, they may be provided radially extending in the radial direction on the nozzle ring outer flange main surface 322. Knurling may also be used to provide irregularities in a twill pattern on the nozzle ring outer flange main surface 322.

[0045] The surface treatment may be applied to at least the flange main surface abutting region 322a of the nozzle ring outer flange main surface 322. The flange main surface non-abutting region 322b may or may not be surface treated to increase the coefficient of friction. The flange main surface abutting region 322a may include a region that has been surface treated to increase the coefficient of friction. The entire flange main surface abutting region 322a may be surface treated to increase the coefficient of friction. The flange main surface abutting region 322a may be surface treated to increase the coefficient of friction only on a portion of the flange main surface abutting region 322a.

[0046] A high coefficient of friction of the nozzle ring outer flange main surface 322 means that the surface roughness of the nozzle ring outer flange main surface 322 is high. For example, the drive ring support surface 32d slides against the drive ring main surface 351. The surface roughness of the sliding surface is generally small. Therefore, the surface roughness of the nozzle ring outer flange main surface 322 is greater than the surface roughness of the drive ring support surface 32d. Similarly, the surface roughness of the nozzle ring outer flange main surface 322 is greater than the surface roughness of the nozzle ring main surface 32e, which is the sliding surface against the nozzle vane 34.

[0047] There are also separated surfaces that do not contact other components, such as the drive ring support outer peripheral surface 325 and the nozzle ring outer flange outer peripheral surface 321. The surface roughness of the separated surfaces that do not contact other components is greater than that of sliding surfaces such as the drive ring support surface 32d. The surface roughness of the nozzle ring outer flange main surface 322 is the same as or greater than that of the drive ring support outer peripheral surface 325. The surface roughness of the nozzle ring outer flange main surface 322 is the same as or greater than that of the nozzle ring outer flange outer peripheral surface 321.

[0048] The relationship between surface roughness and friction may be treated in the same manner as surface treatments that increase the coefficient of friction. The region having a surface roughness designed to increase the coefficient of friction may be formed at least in the flange main surface abutment region 322a of the nozzle ring outer flange main surface 322. The surface roughness of the flange main surface non-abutment region 322b may be a surface roughness designed to increase the coefficient of friction, or may be a different surface roughness. The surface roughness of the flange main surface non-abutment region 322b may be a surface roughness designed to increase the coefficient of friction over the entire flange main surface abutment region 322a. The surface roughness of the flange main surface non-abutment region 322b may be a surface roughness designed to increase the coefficient of friction over only a portion of the flange main surface abutment region 322a.

[0049] The purpose of increasing the friction coefficient of the nozzle ring outer flange main surface 322 is to suppress slight movement of the nozzle ring outer flange main surface 322 relative to the turbine housing flange back surface 112. Therefore, surface processing to increase the friction coefficient and processing to define the surface roughness may be performed on the turbine housing flange back surface 112 that is in contact with the nozzle ring outer flange main surface 322.

[0050] The surface treatment to increase the friction coefficient and the treatment to define the surface roughness may be applied only to the nozzle ring outer flange main surface 322, and not to the turbine housing flange back surface 112. The surface treatment to increase the friction coefficient and the treatment to define the surface roughness may not be applied to the nozzle ring outer flange main surface 322, and may be applied only to the turbine housing flange back surface 112. The surface treatment to increase the friction coefficient and the treatment to define the surface roughness may be applied to both the nozzle ring outer flange main surface 322 and the turbine housing flange back surface 112.

[0051] By increasing the friction force between the nozzle ring outer flange main surface 322 and the turbine housing flange back surface 112, it is possible to suppress slight movement of the variable displacement mechanism 30 relative to the turbine housing 11. This effect is even more pronounced when the turbocharger 1 is in operation.

[0052] When the turbocharger 1 is in operation, high-temperature gas flows through the variable displacement mechanism 30. As a result, the components that make up the variable displacement mechanism 30 are thermally deformed. The thermal deformation causes a slight misalignment between the components. For example, the distance from the heat shield 61 to the bearing housing 3 may increase. If the distance from the heat shield 61 to the bearing housing 3 increases, the coned disc spring load generated by the coned disc spring 62 decreases. Because the coned disc spring load is a force that presses the variable displacement mechanism 30 against the turbine housing 11, a decrease in the coned disc spring load generated by the coned disc spring 62 reduces the force that presses the variable displacement mechanism 30 against the turbine housing 11. The force that presses the variable displacement mechanism 30 against the turbine housing 11 generates a frictional force that suppresses the slight movement of the variable displacement mechanism 30 relative to the turbine housing 11, as described above. Therefore, a decrease in the force that presses the variable displacement mechanism 30 against the turbine housing 11 reduces the frictional force. As a result, the force restraining the variable displacement mechanism 30 relative to the turbine housing 11 is weakened, making it easier for the variable displacement mechanism 30 to move slightly relative to the turbine housing 11 due to an external force.

[0053] Another example of a cause of this is a decrease in the Young's modulus of the disc spring 62 due to an increase in the temperature of the disc spring 62. A decrease in Young's modulus leads to a decrease in the spring load. This also reduces the frictional force, making the variable displacement mechanism 30 more likely to move slightly relative to the turbine housing 11.

[0054] When the turbocharger 1 is in an operating state, the force pressing the variable displacement mechanism 30 against the turbine housing 11 tends to weaken. The frictional force is the product of the pressing force and the friction coefficient. Therefore, if the friction coefficient is sufficiently large, even if a force that induces relative slight movement between the variable displacement mechanism 30 and the turbine housing 11 due to an external force acts when the pressing force is in a reduced state, it is possible to ensure a frictional force that can counteract this force.

[0055] In terms of the purpose of suppressing the micro-movement of the variable displacement mechanism 30 relative to the turbine housing 11, the effect of the processing for increasing the friction coefficient can be further enhanced by applying it to another portion.

[0056] Figure 4 is an enlarged view of region S2 in Figure 1. Figure 4 shows an enlarged view of the heat shield 61 and the disc spring 62. In Figure 4, an example of applying processing to increase the coefficient of friction to three locations will be described. First, processing to increase the coefficient of friction may be applied to the location where the heat shield 61 and the nozzle ring 32 contact. Second, processing to increase the coefficient of friction may be applied to the location where the heat shield 61 and the disc spring 62 contact. Third, processing to increase the coefficient of friction may be applied to the location where the disc spring 62 and the bearing housing 3 contact.

[0057] The heat shield 61 will now be described. The heat shield 61 has a heat shield main body 61a and a heat shield flange 61f. The heat shield main body 61a is ring-shaped and has a heat shield main body inner circumferential surface 611 and a heat shield main body outer circumferential surface 612. The heat shield main body inner circumferential surface 611 faces the bearing housing receiving surface 114. The heat shield main body inner circumferential surface 611 is in contact with the bearing housing receiving surface 114. The heat shield main body outer circumferential surface 612 faces the end of the nozzle ring 32. The end of the nozzle ring 32 is the nozzle ring inner flange 32f2 that protrudes from the inner circumferential surface surrounding the nozzle ring shaft hole 32h. More specifically, the heat shield main body outer circumferential surface 612 is in contact with the nozzle ring inner flange inner circumferential surface 326.

[0058] The heat shield body 61a has a heat shield body main surface 613. The heat shield body main surface 613 faces the turbine wheel back surface 121 of the turbine wheel 12. The heat shield body main surface 613 is not in contact with the turbine wheel back surface 121. A gap exists between the heat shield body main surface 613 and the turbine wheel back surface 121.

[0059] The heat shield body 61a has a heat shield body back surface 614. The heat shield body back surface 614 faces the bearing housing 3. Specifically, the heat shield body back surface 614 faces the bearing housing bottom surface 115. The heat shield body back surface 614 does not contact the bearing housing bottom surface 115. A gap exists between the heat shield body back surface 614 and the bearing housing bottom surface 115. A disc spring 62 is disposed in this gap. As shown in FIG. 1 , the bearing housing 3 abuts against the turbine housing 11 at an abutment portion 3p. The distance from the heat shield body back surface 614 to the bearing housing bottom surface 115 is determined by this abutment.

[0060] The heat shield plate flange 61f has a heat shield plate flange outer peripheral surface 615. The heat shield plate flange outer peripheral surface 615 faces the nozzle ring shaft hole inner peripheral surface 32h1. The heat shield plate flange outer peripheral surface 615 does not contact the nozzle ring shaft hole inner peripheral surface 32h1. A gap exists between the heat shield plate flange outer peripheral surface 615 and the nozzle ring shaft hole inner peripheral surface 32h1.

[0061] The heat shield plate flange 61f has a heat shield plate flange main surface 616 (first intermediate member abutment surface). The heat shield plate flange main surface 616 faces the nozzle ring inner flange back surface 327 (second variable capacitance abutment surface) of the nozzle ring inner flange 32f2. The entire surface of the heat shield plate flange main surface 616 contacts a portion of the nozzle ring inner flange back surface 327. The heat shield plate flange main surface 616 is pressed against the nozzle ring inner flange back surface 327. The location where the heat shield plate flange main surface 616 is pressed against the nozzle ring inner flange back surface 327 is the first location described above.

[0062] Therefore, at least one of the heat shield flange main surface 616 and the nozzle ring inner flange back surface 327 may be subjected to a surface treatment that increases the friction coefficient or a surface roughness treatment that increases the friction coefficient.

[0063] The heat shield flange 61f has a heat shield flange back surface 617. The heat shield flange back surface 617 and the heat shield main body back surface 614 form the heat shield back surface 61c. The heat shield back surface 61c faces the bearing housing bottom surface 115. The heat shield back surface 61c does not contact the bearing housing bottom surface 115. A gap exists between the heat shield back surface 61c and the bearing housing bottom surface 115. This gap is managed by the bearing housing 3 being abutted against the turbine housing 11, as described above. A disc spring 62 is disposed in this gap.

[0064] The following describes the disc spring 62. The disc spring 62 is a ring-shaped member. The disc spring 62 has a disc spring inner peripheral surface 621 and a disc spring outer peripheral surface 622. The disc spring inner peripheral surface 621 is misaligned in the direction of the rotation axis AX with respect to the disc spring outer peripheral surface 622. To eliminate this misalignment, the disc spring 62 is compressed along the direction of the rotation axis AX, thereby generating an elastic force.

[0065] The disc spring 62 has a disc spring main surface 623 (first biasing member abutment surface). The disc spring main surface 623 faces the heat shield plate back surface 61c. The disc spring main surface 623 is in contact with the heat shield plate back surface 61c. The disc spring main surface 623 is pressed against the heat shield plate back surface 61c (second intermediate member abutment surface). The disc spring main surface 623 is pressed against the heat shield plate flange back surface 617. A disc spring main surface outer peripheral portion 623a of the disc spring main surface 623 is pressed against the heat shield plate flange back surface 617. A portion of the disc spring main surface 623 is in contact with the heat shield plate flange back surface 617. The disc spring main surface inner peripheral portion 623b is not in contact with the heat shield plate flange back surface 617. The area of ​​the disc spring main surface 623 that contacts the heat shield plate flange rear surface 617 varies depending on the degree to which the disc spring 62 is crushed. The location where the disc spring main surface 623 is pressed against the heat shield plate flange rear surface 617 is the second location described above.

[0066] Therefore, at least one of the main surface 623 of the disc spring and the rear surface 617 of the heat shield flange may be subjected to a surface treatment that increases the coefficient of friction or a surface roughness treatment that increases the coefficient of friction.

[0067] The disc spring 62 has a disc spring back surface 624 (second biasing member abutment surface). The disc spring back surface 624 faces the bearing housing bottom surface 115 (second housing abutment surface). The disc spring back surface 624 faces the bearing housing bottom surface 115. The disc spring back surface 624 is pressed against the bearing housing bottom surface 115. A disc spring back surface inner peripheral portion 624a of the disc spring back surface 624 is pressed against the bearing housing bottom surface 115. A portion of the disc spring back surface 624 is in contact with the bearing housing bottom surface 115. The disc spring back surface outer peripheral portion 624b is not in contact with the bearing housing bottom surface 115. The area of ​​the disc spring main surface 623 that is in contact with the bearing housing bottom surface 115 changes depending on the extent to which the disc spring 62 is compressed. The portion of disc spring back surface 624 that is pressed against bearing housing bottom surface 115 is the third portion described above.

[0068] Therefore, a surface treatment to increase the coefficient of friction may be applied to at least one of the disc spring back surface 624 and the bearing housing bottom surface 115. Furthermore, a surface roughening treatment to increase the coefficient of friction may be applied to at least one of the disc spring back surface 624 and the bearing housing bottom surface 115.

[0069] <Action and effect> In short, the turbocharger 1 of this embodiment includes the turbine wheel 12, a turbine housing 11 including a flow path through which gas received from the inlet 14s flows, a variable displacement mechanism 30 that is disposed in the turbine housing 11 and receives gas from the flow path and directs it to the turbine wheel 12, and a disc spring 62 that applies a biasing force to the variable displacement mechanism 30 to press the variable displacement mechanism 30 against the turbine housing 11. The turbine housing 11 has a turbine housing flange back surface 112 that contacts the variable displacement mechanism 30 along the direction of the rotation axis AX of the turbine wheel 12. The variable displacement mechanism 30 has a nozzle ring outer flange main surface 322 that contacts the turbine housing flange back surface 112 along the direction of the rotation axis AX. At least one of the turbine housing flange back surface 112 and the nozzle ring outer flange main surface 322 is processed to increase the coefficient of friction.

[0070] At the portion where the turbine housing 11 contacts the variable displacement mechanism 30, a frictional force is generated according to the biasing force generated by the disc spring 62 and the friction coefficient. At least one of the turbine housing flange back surface 112 and the nozzle ring outer flange main surface 322 is processed to increase the friction coefficient. This makes it possible to increase the frictional force, which is determined by the product of the friction coefficient and the biasing force. The frictional force can suppress the occurrence of relative micro-motion that occurs between the turbine housing 11 and the variable displacement mechanism 30. This makes it possible to suppress the occurrence of relative micro-motion between the parts.

[0071] The turbocharger 1 further includes a bearing housing 3 that rotatably supports the rotating shaft 2 to which the turbine wheel 12 is fixed, and an annular heat shield 61 that is disposed between the turbine housing 11 and the variable displacement mechanism 30. The variable displacement mechanism 30 includes a nozzle ring shaft hole 32h through which the turbine wheel 12 or the rotating shaft 2 is inserted, and a nozzle ring inner flange back surface 327 that surrounds the nozzle ring shaft hole 32h. The heat shield 61 includes a heat shield flange main surface 616 that contacts the nozzle ring inner flange back surface 327. At least one of the nozzle ring inner flange back surface 327 and the heat shield flange main surface 616 is processed to increase the coefficient of friction. This configuration can suppress relative micromotion between the variable displacement mechanism 30 and the heat shield 61.

[0072] The turbocharger 1 further includes a bearing housing 3 that rotatably supports the rotary shaft 2 to which the turbine impeller 12 is fixed, and an annular heat shield 61 that is arranged between the turbine housing 11 and the variable displacement mechanism 30. The heat shield 61 has a heat shield flange back surface 617 that faces the bearing housing 3 and with which the disc springs 62 contact. The disc springs 62 have disc spring main surfaces 623 that contact the heat shield flange back surface 617. At least one of the heat shield flange back surface 617 and the disc spring main surfaces 623 is processed to increase the coefficient of friction. With this configuration, the occurrence of relative micromotion between the disc springs 62 and the heat shield 61 can be suppressed.

[0073] The turbocharger 1 further includes a bearing housing 3 that rotatably supports the rotating shaft 2 to which the turbine wheel 12 is fixed. The bearing housing 3 has a bearing housing bottom surface 115 that contacts the disc spring 62 along the direction of the rotation axis AX. The disc spring 62 has a disc spring back surface 624 that contacts the bearing housing bottom surface 115. At least one of the bearing housing bottom surface 115 and the disc spring back surface 624 is processed to increase the coefficient of friction. With this configuration, the occurrence of relative micromotion between the disc spring 62 and the bearing housing 3 can be suppressed.

[0074] The turbocharger 1 includes a turbine wheel 12, a turbine housing 11 including a flow path through which gas received from an inlet 14s flows, a variable capacity mechanism 30 that is disposed in the turbine housing 11 and receives gas from the flow path and directs it to the turbine wheel 12, the variable capacity mechanism 30 including a disk-shaped nozzle ring 32 having a main surface facing the turbine wheel 12 and a plurality of nozzle vanes 34 that are disposed on the main surface side of the nozzle ring 32 and form a plurality of nozzle flow paths through which the gas is directed, and a disc spring 62 that applies a biasing force to the variable capacity mechanism 30 to press the variable capacity mechanism 30 against the turbine housing 11. The turbine housing 11 has a turbine housing flange back surface 112 that contacts the variable capacity mechanism 30 along the direction of the rotational axis AX of the turbine wheel 12. The variable capacity mechanism 30 has a nozzle ring outer flange main surface 322 that contacts the turbine housing flange back surface 112 along the direction of the rotational axis AX. The nozzle ring 32 has a separation surface that separates it from a first part other than the nozzle ring 32, and a sliding surface on which a second part other than the nozzle ring 32 slides. The surface roughness of at least one of the turbine housing flange back surface 112 and the nozzle ring outer flange main surface 322 is greater than the surface roughness of the separation surface.

[0075] At the contact point between the turbine housing 11 and the variable displacement mechanism 30, a frictional force is generated according to the biasing force generated by the disc spring 62 and the friction coefficient. The surface roughness of at least one of the turbine housing flange back surface 112 and the nozzle ring outer flange main surface 322 is greater than the surface roughness of the separation surface. Therefore, it is possible to increase the frictional force, which is determined by the product of the friction coefficient corresponding to the surface roughness and the biasing force. This frictional force can suppress the occurrence of relative micromotion between the turbine housing 11 and the variable displacement mechanism 30. Therefore, the occurrence of relative micromotion between the components can be suppressed.

[0076] The surface roughness of at least one of the turbine housing flange back surface 112 and the nozzle ring outer flange main surface 322 is greater than the surface roughness of the sliding surface. This configuration also makes it possible to suppress the occurrence of relative micro-motion between the parts.

[0077] [Modification] The turbocharger of the present disclosure is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present disclosure.

[0078] The variable displacement mechanism 30 is positioned relative to the bearing housing 3. The protrusion 3a (second housing shoulder surface) of the bearing housing 3 is fitted into the nozzle ring shaft hole 32h (first arrangement hole). The protrusion outer surface 3a1 of the protrusion 3a contacts the nozzle ring shaft hole inner circumferential surface 32h1 (first arrangement hole inner circumferential portion). Therefore, the variable displacement mechanism 30 and the bearing housing 3 cooperate to form a spigot structure 39. The rib 32r and the protrusion 3a of the bearing housing 3 form the spigot structure 39. The position of the variable displacement mechanism 30 relative to the bearing housing 3 is determined by the spigot structure 39.

[0079] At least one of the outer peripheral surface 3a1 of the protrusion 3a of the bearing housing 3 and the inner peripheral surface 32h1 of the nozzle ring shaft hole may be subjected to a surface treatment to increase the coefficient of friction or a surface roughness treatment to increase the coefficient of friction. This portion is not related to the micro-movement of the variable displacement mechanism 30 caused by a decrease in the pressing force of the disc spring 62, as described in the present disclosure. However, by increasing the coefficient of friction between the outer peripheral surface 3a1 of the protrusion 3a and the inner peripheral surface 32h1 of the nozzle ring shaft hole, micro-movement of the variable displacement mechanism 30 around the rotation axis AX relative to the turbine housing 11 can be suppressed. This configuration also suppresses micro-movement of the variable displacement mechanism 30 relative to the turbine housing 11.

[0080] In short, the turbocharger 1 further includes a bearing housing 3 that rotatably supports the rotating shaft 2 to which the turbine wheel 12 is fixed. The variable displacement mechanism 30 has a nozzle ring shaft hole 32h through which the turbine wheel 12 or the rotating shaft 2 is inserted. The nozzle ring shaft hole 32h includes a nozzle ring shaft hole inner circumferential surface 32h1 on which the protruding portion 3a of the bearing housing 3 is disposed. The protruding portion 3a has a protruding portion outer circumferential surface 3a1 that contacts the nozzle ring shaft hole inner circumferential surface 32h1. At least one of the nozzle ring shaft hole inner circumferential surface 32h1 and the protruding portion outer circumferential surface 3a1 of the protruding portion 3a of the bearing housing 3 is processed to increase the coefficient of friction. This configuration makes it possible to suppress relative micromotion between the variable displacement mechanism 30 and the bearing housing 3.

[0081] [Note] The present disclosure includes the following configurations.

[0082] The turbocharger disclosed herein is [1] "a turbocharger comprising: a turbine wheel; a first housing including a flow path through which gas received from an inlet flows; a variable displacement mechanism that is disposed in the first housing and receives the gas from the flow path and directs it to the turbine wheel; and a biasing member that applies a biasing force to the variable displacement mechanism to press the variable displacement mechanism against the first housing, wherein the first housing has a first housing abutment surface that contacts the variable displacement mechanism along the direction of the rotation axis of the turbine wheel, and the variable displacement mechanism has a first variable displacement mechanism abutment surface that contacts the first housing abutment surface along the direction of the rotation axis, and at least one of the first housing abutment surface and the first variable displacement mechanism abutment surface is treated to increase the coefficient of friction."

[0083] The turbocharger disclosed herein is [2] "the turbocharger described in [1] above, further comprising: a second housing that rotatably supports a rotating shaft to which the turbine wheel is fixed; and an annular intermediate member that is arranged between the first housing and the variable displacement mechanism, wherein the variable displacement mechanism has a first arrangement hole through which the turbine wheel or the rotating shaft is inserted, and a second variable displacement mechanism abutment surface that surrounds the first arrangement hole, the intermediate member has a first intermediate member abutment surface that abuts on the second variable displacement mechanism abutment surface, and at least one of the second variable displacement mechanism abutment surface and the first intermediate member abutment surface is treated to increase the coefficient of friction."

[0084] The turbocharger disclosed herein is [3] "the turbocharger described in [1] or [2] above, further comprising: a second housing that rotatably supports a rotating shaft to which the turbine wheel is fixed; and an annular intermediate member that is arranged between the first housing and the variable capacity mechanism, wherein the intermediate member has a second intermediate member abutment surface that faces the second housing and with which the biasing member contacts, the biasing member has a first biasing member abutment surface that contacts the second intermediate member abutment surface, and at least one of the second intermediate member abutment surface and the first biasing member abutment surface is treated to increase the coefficient of friction."

[0085] The turbocharger of the present disclosure is [4] "the turbocharger according to any one of the above [1] to [3], further comprising a second housing that rotatably supports a rotating shaft to which the turbine wheel is fixed, the second housing having a second housing abutment surface along the direction of the rotation axis with which the biasing member contacts, the biasing member having a second biasing member abutment surface that contacts the second housing abutment surface, and at least one of the second housing abutment surface and the second biasing member abutment surface is treated to increase the coefficient of friction."

[0086] The turbocharger disclosed herein is [5] "the turbocharger according to any one of the above [1] to [4], further comprising a second housing that rotatably supports a rotating shaft to which the turbine wheel is fixed, the variable displacement mechanism having a first arrangement hole through which the turbine wheel or the rotating shaft is inserted, the first arrangement hole including a first arrangement hole inner circumferential surface portion in which a second housing shoulder of the second housing is arranged, the second housing shoulder having a second housing shoulder surface in contact with the first arrangement hole inner circumferential surface portion, and at least one of the first arrangement hole inner circumferential surface portion and the second housing shoulder surface is processed to increase the coefficient of friction."

[0087] Another turbocharger of the present disclosure is [6] "comprised of a turbine wheel and a first housing including a flow path through which gas received from an inlet flows; a variable capacity mechanism that is disposed in the first housing and receives the gas from the flow path and guides it to the turbine wheel, the variable capacity mechanism having a disk-shaped nozzle ring having a main surface facing the turbine wheel, and a plurality of nozzle vanes that are disposed on the main surface side of the nozzle ring and form a plurality of nozzle flow paths through which the gas is guided; and a biasing member that applies a biasing force to the variable capacity mechanism to press the variable capacity mechanism against the first housing. the first housing has a first housing abutment surface that abuts on the variable capacity mechanism along the direction of the rotation axis of the turbine impeller, the variable capacity mechanism has a first variable capacity mechanism abutment surface that abuts on the first housing abutment surface along the direction of the rotation axis, the nozzle ring has a separation surface that is separate from a first component other than the nozzle ring, and a sliding surface on which a second component other than the nozzle ring slides, and the surface roughness of at least one of the first housing abutment surface and the first variable capacity mechanism abutment surface is greater than the surface roughness of the separation surface.

[0088] Another turbocharger of the present disclosure is [7] "The turbocharger described in [6] above, wherein the surface roughness of at least one of the first housing abutment surface and the first variable displacement mechanism abutment surface is greater than the surface roughness of the sliding surface."

[0089] Another turbocharger of the present disclosure is [8] "the turbocharger described in [6] or [7] above, wherein the first part is the first housing, and the separating surface is the outer peripheral surface of a nozzle ring that faces the inner peripheral surface of the first housing and is separated from the inner peripheral surface of the first housing."

[0090] Another turbocharger of the present disclosure is [9] "the turbocharger according to any one of the above [6] to [8], wherein the second part is the nozzle vane, and the sliding surface is the main surface of the nozzle ring on which the plurality of nozzle vanes slide." [Explanation of symbols]

[0091] 1. Turbocharger 2 rotation axes 3 Bearing housing (second housing) 3a Protrusion (second housing shoulder) 3a1 outer circumferential surface of protrusion (second housing shoulder) 11 Turbine housing (first housing) 112 Turbine housing flange back surface (first housing abutment surface) 115 Bearing housing bottom surface (second housing contact surface) 12 Turbine wheel 13 Scroll flow passage (flow passage) 14s inlet 30 Variable capacity mechanism 32 Nozzle ring 322 Nozzle ring outer flange main surface (first variable displacement mechanism abutment surface) 327 Nozzle ring inner flange back surface (second variable volume contact surface) 32h Nozzle ring shaft hole (first arrangement hole) 32h1 Nozzle ring shaft hole inner circumferential surface (first arrangement hole inner circumferential surface) 34 Nozzle vane 61 Heat shield plate (intermediate member) 616 Heat shield flange main surface (first intermediate member abutment surface) 61c Back surface of heat shield plate (contact surface of second intermediate member) 62 Disc spring (biasing member) 623 Disc spring main surface (first biasing member contact surface) 624 Disc spring back surface (second biasing member contact surface) 325 Outer surface of drive ring support AX Rotation axis

Claims

1. A turbine wheel; a first housing including a flow path through which gas received from the inlet flows; a variable displacement mechanism that is disposed in the first housing and receives the gas from the flow path and guides the gas to the turbine wheel; a biasing member that applies a biasing force to the variable displacement mechanism to press the variable displacement mechanism against the first housing, the first housing has a first housing abutment surface that contacts the variable displacement mechanism along the direction of the rotation axis of the turbine wheel, the variable displacement mechanism has a first variable displacement mechanism abutment surface that contacts the first housing abutment surface along the direction of the rotation axis, a supercharger, wherein at least one of the first housing abutment surface and the first variable displacement mechanism abutment surface is subjected to processing to increase a coefficient of friction.

2. a second housing that rotatably supports a rotary shaft to which the turbine wheel is fixed; an annular intermediate member disposed between the first housing and the variable displacement mechanism, the variable displacement mechanism includes a first arrangement hole through which the turbine wheel or the rotary shaft is inserted, and a second variable displacement mechanism abutment surface surrounding the first arrangement hole, the intermediate member has a first intermediate member abutment surface that contacts the second variable displacement mechanism abutment surface, The turbocharger according to claim 1 , wherein at least one of the second variable displacement mechanism abutment surface and the first intermediate member abutment surface is subjected to a treatment to increase a coefficient of friction.

3. a second housing that rotatably supports a rotary shaft to which the turbine wheel is fixed; an annular intermediate member disposed between the second housing and the variable displacement mechanism, the intermediate member has a second intermediate member abutment surface that faces the second housing and with which the biasing member comes into contact, the biasing member has a first biasing member abutment surface that contacts the second intermediate member abutment surface, The turbocharger according to claim 1 , wherein at least one of the second intermediate member abutment surface and the first biasing member abutment surface is subjected to a treatment to increase a coefficient of friction.

4. a second housing that rotatably supports a rotation shaft to which the turbine wheel is fixed, the second housing has a second housing abutment surface with which the biasing member comes into contact along the direction of the rotation axis, the biasing member has a second biasing member abutment surface that contacts the second housing abutment surface, The turbocharger according to claim 1 , wherein at least one of the second housing contact surface and the second biasing member contact surface is subjected to a treatment to increase a coefficient of friction.

5. a second housing that rotatably supports a rotation shaft to which the turbine wheel is fixed, the variable capacity mechanism has a first arrangement hole through which the turbine wheel or the rotary shaft is inserted, the first arrangement hole includes a first arrangement hole inner circumferential surface portion on which a second housing shoulder portion of the second housing is arranged, the second housing shoulder portion has a second housing shoulder surface that contacts the inner peripheral surface portion of the first arrangement hole, The turbocharger according to claim 1 , wherein at least one of an inner peripheral surface of the first arrangement hole and the second housing shoulder surface is subjected to a process for increasing a coefficient of friction.

6. A turbine wheel; a first housing including a flow path through which gas received from the inlet flows; a variable displacement mechanism that is disposed in the first housing, receives the gas from the flow path, and guides it to the turbine wheel, the variable displacement mechanism including: a disk-shaped nozzle ring having a main surface facing the turbine wheel; and a plurality of nozzle vanes that are disposed on the main surface side of the nozzle ring and form a plurality of nozzle flow paths that guide the gas; a biasing member that applies a biasing force to the variable displacement mechanism to press the variable displacement mechanism against the first housing, the first housing has a first housing abutment surface that contacts the variable displacement mechanism along the direction of the rotation axis of the turbine wheel, the variable displacement mechanism has a first variable displacement mechanism abutment surface that contacts the first housing abutment surface along the direction of the rotation axis, the nozzle ring has a separation surface that separates it from a first component separate from the nozzle ring, and a sliding surface on which a second component separate from the nozzle ring slides; a surface roughness of at least one of the first housing contact surface and the first variable displacement mechanism contact surface being greater than a surface roughness of the separation surface;

7. The turbocharger according to claim 6, wherein a surface roughness of at least one of the first housing abutment surface and the first variable displacement mechanism abutment surface is greater than a surface roughness of the sliding surface.

8. the first component is the first housing, The turbocharger according to claim 6 or 7, wherein the separation surface is an outer circumferential surface of a nozzle ring that faces the inner circumferential surface of the first housing and is spaced apart from the inner circumferential surface of the first housing.

9. the second component is the nozzle vane; The turbocharger according to claim 6, wherein the sliding surface is a main surface of the nozzle ring on which the plurality of nozzle vanes slide.

10. The variable capacity mechanism comprises a disk-shaped nozzle ring having a main surface facing the turbine wheel, and a plurality of nozzle vanes arranged on the main surface side of the nozzle ring to form a plurality of nozzle flow paths for guiding the gas; the nozzle ring has a separation surface that is spaced from the first housing; The turbocharger according to claim 1 , wherein a surface roughness of at least one of the first housing contact surface and the first variable displacement mechanism contact surface is greater than a surface roughness of the separation surface.

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