Seal structure for supercharger

Abstract

This seal structure for a supercharger comprises: a rotary member including a rotary shaft of the supercharger and a rotary wheel provided toward one end of the rotary shaft; a stationary member including a housing accommodating the rotary member; a bearing for rotatably supporting the rotary shaft; and a seal member provided in a seal gap that is formed between the rotary member and the stationary member and that establishes communication between a first space in which the rotary wheel is accommodated and a second space in which the bearing is accommodated. The stationary member includes a stationary-side inner circumferential surface that defines the seal gap and a stationary-side end surface that extends from an edge of the stationary-side inner circumferential surface on the second space side, along a radial direction of the rotary shaft. The stationary-side end surface includes a slope that is provided in a predetermined circumferential range below the axis of the rotary shaft and that, moving downward from the edge of the stationary-side inner circumferential surface on the second space side, is inclined toward the second space side in the axial direction of the rotary shaft.

Description

Turbocharger seal structure

[0001] The present disclosure relates to a seal structure for a turbocharger.

[0002] A turbocharger includes a rotor (rotating body) including a rotating shaft, a turbine impeller attached to one side of the rotating shaft, and a compressor impeller attached to the other side of the rotating shaft; bearings that rotatably support the rotating shaft between the turbine impeller and the compressor impeller; and a casing (stationary body) that houses the rotor and the bearings. Since the bearings of a turbocharger support the rotating shaft that rotates at high speed, they are prone to become hot, and insufficient lubrication can lead to seizure. For this reason, the bearings are lubricated and cooled by supplying lubricating oil to the bearings. Some turbochargers include a seal ring that seals between the outer surface of the rotating body, such as the rotor, and the inner surface of the stationary body, such as the casing, to prevent leakage of the lubricating oil supplied to the bearings to the compressor side or the turbine side (see, for example, Patent Document 1).

[0003] JP 2008-232124 A

[0004] In a turbocharger equipped with a sealing mechanism using a seal ring, there is a risk of lubricating oil leakage. Specifically, lubricating oil may accumulate in the space between the outer surface of the rotating body to which the seal ring is attached and the inner surface of the stationary body, and the lubricating oil accumulated in the space may leak into the space on the opposite side of the seal ring.

[0005] In view of the above circumstances, at least one embodiment of the present invention has an object to provide a seal structure for a turbocharger that can suppress leakage of lubricating oil.

[0006] A seal structure for a turbocharger according to at least one embodiment of the present invention comprises: a rotating member including at least a rotating shaft of the turbocharger and a rotating wheel provided on one end side of the rotating shaft; a stationary member including at least a housing that accommodates the rotating member; a bearing that rotatably supports the rotating shaft; and a seal member provided in a seal gap formed between the rotating member and the stationary member, the seal gap communicating between a first space that accommodates the rotating wheel and a second space that accommodates the bearing, wherein the rotating member includes at least a rotating-side outer peripheral surface that defines the seal gap, and the stationary member includes a stationary-side inner peripheral surface that defines the seal gap, and a stationary-side end face that extends radially of the rotating shaft from an edge of the stationary-side inner peripheral surface on the second space side, The stationary side end face includes a slope provided in a predetermined circumferential range below the axis of the rotating shaft, and includes a slope that inclines toward the second space in the axial direction of the rotating shaft as it extends downward from the edge of the stationary side inner surface on the second space side.

[0007] According to at least one embodiment of the present invention, there is provided a seal structure for a turbocharger that can suppress leakage of lubricating oil.

[0008] Fig. 1 is a schematic cross-sectional view showing a cross section along the axis of a turbocharger including a seal structure for a turbocharger according to one embodiment; Fig. 2 is a schematic cross-sectional view showing a cross section along the axis of the seal structure for a turbocharger according to one embodiment; Fig. 3 is a schematic view showing the seal structure for a turbocharger according to one embodiment as viewed from the second space side; Fig. 4 is a schematic view showing the vicinity of a slope in the seal structure for a turbocharger according to one embodiment as viewed from above; Fig. 5 is a schematic cross-sectional view showing a cross section along the axis of the seal structure for a turbocharger according to one embodiment;

[0009] Hereinafter, several embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention.

[0010] (Turbocharger) Fig. 1 is a schematic cross-sectional view showing a cross section along an axis of a turbocharger including a seal structure for a turbocharger according to one embodiment. As shown in Fig. 1, the turbocharger 1 includes a rotating shaft 11, a turbine wheel 12A provided on one end of the rotating shaft 11, a compressor wheel 12B provided on the other end of the rotating shaft 11, a bearing 13 that rotatably supports the rotating shaft 11, and a housing 14 that accommodates the rotating shaft 11, the turbine wheel 12A, the compressor wheel 12B, and the bearing 13.

[0011] The bearing 13 is supported by a housing 14. The rotating shaft 11 is supported by the bearing 13 between the turbine wheel 12A and the compressor wheel 12B, and is thereby rotatable about an axis LA of the rotating shaft 11.

[0012] Hereinafter, the direction in which the axis LA of the rotating shaft 11 extends is defined as the axial direction of the rotating shaft 11 (turbocharger 1), and the direction perpendicular to the axis LA is defined as the radial direction of the rotating shaft 11 (turbocharger 1). In the axial direction of the rotating shaft 11 (turbocharger 1), the side where the turbine wheel 12A is located relative to the compressor wheel 12B is defined as the turbine side, and the side where the compressor wheel 12B is located relative to the turbine wheel 12A is defined as the compressor side.

[0013] The turbine wheel 12A is configured to rotate by the energy of exhaust gas discharged from the engine and guided to the turbine wheel 12A. The compressor wheel 12B rotates together with the rotary shaft 11 in conjunction with the rotation of the turbine wheel 12A. The turbocharger 1 is configured to compress gas (e.g., air) guided to the compressor wheel 12B by the rotation of the compressor wheel 12B, increase the density of the gas, and send the gas to a supply destination (e.g., the engine).

[0014] (Sealing structure of turbocharger) Fig. 2 is a schematic cross-sectional view showing a cross section along the axis of the sealing structure of a turbocharger according to one embodiment. Fig. 2 shows an area surrounded by a two-dot chain line in Fig. 1. Fig. 3 is a schematic view showing the sealing structure of a turbocharger according to one embodiment as viewed from the second space side. Fig. 4 is a schematic view showing the vicinity of the slope in the sealing structure of a turbocharger according to one embodiment as viewed from above. A sealing structure 2 of a turbocharger according to some embodiments is a sealing structure provided in a turbocharger 1 for suppressing leakage of lubricating oil in the turbocharger 1. As shown in Figs. 1 and 2 , the sealing structure 2 of a turbocharger includes a rotating member 3, a stationary member 4 that houses the rotating member 3, a seal member 5 provided in a seal gap 20 formed between the rotating member 3 and the stationary member 4, and the bearing 13 described above.

[0015] (Rotating member, stationary member) The rotating member 3 is configured to rotate when the turbocharger 1 is driven. The rotating member 3 includes at least a rotating shaft 11 and a rotating wheel 12 provided on one end side of the rotating shaft 11. The stationary member 4 is configured to remain stationary (does not rotate) even when the rotating member 3 rotates when the turbocharger 1 is driven. The stationary member 4 includes at least a housing 14.

[0016] The stationary member 4 (housing 14) accommodates the rotating member 3 and the bearing 13. Inside the stationary member 4 (housing 14), the above-mentioned seal gap 20, a first space 21 that accommodates the rotating wheel 12, and a second space 22 that accommodates the bearing 13 are formed. The seal gap 20 is provided between the first space 21 and the second space 22 in the axial direction of the rotating shaft 11, and connects the first space 21 and the second space 22.

[0017] The rotating member 3 has a rotating-side outer peripheral surface 31 that defines the seal gap 20. The stationary member 4 has a stationary-side inner peripheral surface 41 that defines the seal gap 20. The stationary-side inner peripheral surface 41 is provided further outward in the radial direction of the rotating shaft 11 than the rotating-side outer peripheral surface 31, and faces the rotating-side outer peripheral surface 31 across the annular seal gap 20.

[0018] As shown in Fig. 2, the stationary member 4 has a stationary-side end face 43 that extends from an edge 42 of the stationary-side inner peripheral surface 41 on the second space 22 side toward the outside in the radial direction of the rotating shaft 11. The rotating member 3 may have a rotating-side end face 33 that extends from an edge 32 of the rotating-side outer peripheral surface 31 on the second space 22 side toward the inside in the radial direction of the rotating shaft 11.

[0019] (Sealing Member) The sealing member 5 is configured to seal the gap between the stationary-side inner peripheral surface 41 and the rotating-side outer peripheral surface 31. In the illustrated embodiment, as shown in Fig. 2, the sealing member (seal ring) 5 is disposed in a compressed state between the stationary-side inner peripheral surface 41 and the rotating-side outer peripheral surface 31, with its outer peripheral surface abutting against the stationary-side inner peripheral surface 41 and its inner peripheral surface abutting against the rotating-side outer peripheral surface 31. As shown in Figs. 1 and 2, at least one of the stationary-side inner peripheral surface 41 and the rotating-side outer peripheral surface 31 may be provided with an annular groove extending along the circumferential direction of the rotating shaft 11, into which a portion of the sealing member 5 is fitted.

[0020] (Lubricant Oil System) The turbocharger 1 is configured so that lubricant oil flows into the bearing 13 and the second space 22 in which the bearing 13 is housed. In the embodiment shown in Fig. 1, the housing 14 is formed with a lubricant oil inlet 23 for introducing lubricant oil into the interior thereof, a lubricant oil supply path 24 for guiding the lubricant oil from the lubricant oil inlet 23 to the bearing 13, and a lubricant oil outlet 25 for discharging the lubricant oil to the outside of the housing 14. The lubricant oil supply path 24 is formed with a flow path defined by the inner wall surface of the housing 14, which connects the lubricant oil inlet 23 and the second space 22. The lubricant oil outlet 25 is provided below the second space 22 and communicates with a lower part of the second space 22.

[0021] The lubricating oil introduced into the housing 14 through the lubricating oil inlet 23 is guided to the bearing 13 through the lubricating oil supply passage 24. Most of the lubricating oil guided to the bearing 13 flows downward in the second space 22 and is discharged to the outside of the housing 14 through the lubricating oil outlet 25. Some of the lubricating oil guided to the bearing 13 may flow into the seal gap 20.

[0022] A seal structure 2 of a turbocharger 1 according to some embodiments includes the above-described rotating member 3, the above-described stationary member 4, the above-described bearing 13, and the above-described seal member 5 provided in the seal gap 20. The stationary member 4 includes the above-described stationary-side inner circumferential surface 41 and the above-described stationary-side end face 43. As shown in Figs. 2 and 3 , the stationary-side end face 43 includes a slope 6 provided in a predetermined circumferential range CR below the axis LA of the rotating shaft 11. The slope 6 is inclined toward the second space 22 in the axial direction of the rotating shaft 11 (the direction in which the axis LA of the rotating shaft 11 extends) as it extends downward from an edge 42 of the stationary-side inner circumferential surface 41 on the second space 22 side.

[0023] As shown in FIGS. 2 to 4 , the stationary-side end surface 43 further includes a flat surface 43A provided outside the region where the slope 6 is formed. The flat surface 43A extends radially outward from an edge 42 of the stationary-side inner circumferential surface 41 on the second space 22 side along the radial direction of the rotating shaft 11. As shown in FIG. 4 , of the edge 42 of the stationary-side inner circumferential surface 41 on the second space 22 side, a slope-side edge 42A (the upper edge of the slope 6) that is continuous with the slope 6 has a concave curved shape that is recessed toward the first space 21 in the axial direction of the rotating shaft 11 more than a flat-side edge 42B (the inner circumferential edge of the flat surface 43A that is continuous with the stationary-side inner circumferential surface 41) that is continuous with the flat surface 43A. The slope 6 has a lower edge 44 that is continuous with the flat surface 43A. As shown in FIG. 3 , the lower edge 44 has a convex curved shape that faces downward when viewed from the second space 22 side in the axial direction of the rotating shaft 11.

[0024] The lubricating oil that has flowed into the seal gap 20 accumulates in the lower part of the seal gap 20. At least a part of the lubricating oil that accumulates in the lower part of the seal gap 20 flows down along the slope 6 and is discharged into the second space 22.

[0025] According to the above configuration, the slope 6 provided in the predetermined circumferential range CR below the axis LA of the rotating shaft 11 on the stationary side end face 43 allows the lubricating oil to be discharged from the lower part of the seal gap 20, thereby preventing the lubricating oil from accumulating in the lower part of the seal gap 20. By preventing the lubricating oil from accumulating in the lower part of the seal gap 20, the seal structure 2 for the turbocharger can prevent the lubricating oil from leaking beyond the seal member 5 provided in the seal gap 20 to the first space 21 side (the side where the rotating wheel 12 is located).

[0026] In some embodiments, as shown in Fig. 1, the seal structure 2A(2) for a turbocharger is intended to suppress leakage of lubricating oil from the second space 22 to the first space 21A(21) in which the turbine wheel 12A is housed. The rotating wheel 12 of the seal structure 2A for a turbocharger is made up of the turbine wheel 12A described above. As shown in Fig. 1, the first space 21A, which is the space in which the turbine wheel 12A is housed, and the seal gap 20A(20) are provided closer to the turbine in the axial direction of the rotating shaft 11 than the second space 22 in which the bearing 13 is housed.

[0027] The rotating-side outer peripheral surface 31A (31) may be, for example, the outer peripheral surface of a boss portion protruding from the back surface of the turbine wheel 12A as shown in Fig. 1. The stationary-side inner peripheral surface 41A (41) may be the inner wall surface of the housing 14 that faces the outer peripheral surface of the boss portion of the turbine wheel 12A across the seal gap 20A.

[0028] In some embodiments, as shown in Fig. 1, the seal structure 2B(2) for a turbocharger is intended to suppress leakage of lubricating oil from the second space 22 to the first space 21B(21) in which the compressor wheel 12B is housed. The rotating wheel 12 of the seal structure 2B for a turbocharger is formed of the compressor wheel 12B described above. As shown in Fig. 1, the first space 21B(21) and the seal gap 20B(20), which are the spaces in which the compressor wheel 12B is housed, are provided closer to the compressor in the axial direction of the rotating shaft 11 than the second space 22 in which the bearing 13 is housed.

[0029] The rotating-side outer peripheral surface 31B (31) may be, for example, the outer peripheral surface of an annular sleeve 15 included in the turbocharger 1 as shown in FIG. 1 . The sleeve 15 is attached to the rotating shaft 11 between a compressor wheel 12B (rotating wheel 12) and a bearing 13 in the axial direction of the rotating shaft 11 so as to cover the outer periphery of the rotating shaft 11. The rotating member 3 may further include the sleeve 15. The stationary-side inner peripheral surface 41B (41) may be an inner wall surface of the housing 14 that faces the outer peripheral surface of the sleeve 15 across the seal gap 20B. Furthermore, the rotating-side outer peripheral surface 31 may be the outer peripheral surface of the rotating shaft 11.

[0030] The turbocharger 1 may include both the turbocharger seal structures 2A and 2B. That is, the end face of the stationary-side inner circumferential surface 41A that is continuous with the compressor side and the end face of the stationary-side inner circumferential surface 41B that is continuous with the turbine side may each be the stationary-side end face 43 that includes the slope 6 described above.

[0031] 3 , the slope 6 is formed to include a position P1 vertically below the axis LA of the rotating shaft 11. In this case, one end 61 of the circumferential range CR of the slope 6 is provided on one side in the horizontal direction with respect to the axis LA of the rotating shaft 11. The other end 62 of the circumferential range CR of the slope 6 is provided on the opposite side (the other side) from the one end 61 in the horizontal direction with respect to the axis LA of the rotating shaft 11.

[0032] According to the above configuration, by forming the slope 6 so as to include position P1 vertically below the axis LA of the rotating shaft 11, it is possible to directly discharge the lubricating oil from a lower region 20C (see FIG. 3 ) including position P1 vertically below the axis LA of the rotating shaft 11 in the seal gap 20, which is the portion where the lubricating oil accumulates, to the slope 6. Therefore, the slope 6 including position P1 vertically below can more effectively discharge the lubricating oil from the lower part of the seal gap 20 to the slope 6 than a slope 6 that does not include position P1 vertically below.

[0033] In some embodiments, the slope 6 described above is inclined in the circumferential direction from both ends 61, 62 in the circumferential range CR toward the vertically downward position P1 described above, as shown in FIG. 3 .

[0034] According to the above configuration, by providing the slope 6 with a circumferential inclination from both ends 61, 62 in the circumferential range CR toward the vertically downward position P1, the lubricating oil guided from the seal gap 20 to the slope 6 can flow toward the vertically downward position P1. This causes the lubricating oil to collect near the vertically downward position P1 of the slope 6, and promotes the movement of the lubricating oil along the inclination of the slope 6 due to its own weight, thereby improving the efficiency with which the lubricating oil is discharged via the slope 6.

[0035] 2, in a cross section taken along the axis of the rotating shaft 11, the inclination angle of the slope 6 with respect to an imaginary plane formed by extending the flat surface 43A is defined as θ. In some embodiments, the slope 6 is configured so that the inclination angle θ increases from both ends 61, 62 in the circumferential range CR toward a position P1 vertically below. In this case, the lubricating oil guided from the seal gap 20 to the slope 6 can flow toward the position P1 vertically below, and the lubricating oil can be collected near the position P1 vertically below the slope 6.

[0036] 2 , in a cross section taken along the axis of the rotating shaft 11, the length from the upper edge (slope side edge 42A) of the slope 6 to the lower edge 44 is defined as the slope length L. In some embodiments, the above-described slope 6 is configured so that the slope length L increases from both ends 61, 62 in the circumferential range CR toward a position P1 vertically below. In this case, the lubricating oil guided from the seal gap 20 to the slope 6 can flow toward the position P1 vertically below, and the lubricating oil can be collected near the position P1 vertically below the slope 6.

[0037] If the circumferential range CR of the slope 6 is made too small, the effect of discharging the lubricating oil from the seal gap 20 via the slope 6 will be reduced. On the other hand, if the circumferential range CR of the slope 6 is made too large, an excess slope 6 will be formed in the circumferential range CR, causing the lubricating oil to fall by gravity without passing through the slope 6.

[0038] The circumferential range CR of the slope 6 described above is preferably set in the range of 60° to 120°. In this case, by setting the circumferential range CR of the slope 6 in the range of 60° to 120°, the effect of discharging lubricating oil from the seal gap 20 via the slope 6 can be improved compared to when the circumferential range CR of the slope 6 is set to less than 60°. Furthermore, by setting the circumferential range CR of the slope 6 in the range of 60° to 120°, the formation of an excess slope 6 can be suppressed compared to when the circumferential range CR of the slope 6 is set to a range exceeding 120°, and the work required to form the slope 6 can be shortened.

[0039] It is more preferable that the circumferential range CR of the slope 6 be set in the range of 85° to 95°. In this case, by setting the circumferential range CR of the slope 6 in the range of 85° to 95°, it is possible to effectively prevent an excess slope 6 from being formed while suppressing a decrease in the effect of discharging lubricating oil from the seal gap 20 via the slope 6.

[0040] In some embodiments, as shown in Figure 2, at a position P1 vertically below the axis LA of the rotating shaft 11, the edge 42 (slope side edge 42A) on the stationary side inner surface 41 facing the second space 22 is located closer to the first space 21 than the edge 32 on the rotating side outer surface 31 facing the second space 22.

[0041] According to the above configuration, the shape of the lubricating oil that flows down the rotating side end face 33 makes it difficult for it to enter the seal gap 20, thereby preventing the inflow of lubricating oil into the seal gap 20 and ultimately preventing the accumulation of lubricating oil at the bottom of the seal gap 20.

[0042] Fig. 5 is a schematic cross-sectional view showing a cross section along the axis of a seal structure for a turbocharger according to one embodiment. Fig. 5 illustrates the area surrounded by the two-dot chain line in Fig. 1. In some embodiments, as shown in Fig. 5, the stationary-side end surface 43 includes the slope 6 and a flat surface 43B provided in an area other than the area where the slope 6 is formed. The flat surface 43B is continuous with a lower edge 44 of the slope 6 and extends radially outward from an edge 42 of the stationary-side inner circumferential surface 41 on the second space 22 side along the radial direction of the rotating shaft 11. Below the axis LA of the rotating shaft 11, the flat surface 43B is located closer to the first space 21 than the edge 32 of the rotating-side outer circumferential surface 31 on the second space 22 side. In this case, the shape of the seal makes it difficult for the lubricating oil that flows down the rotating side end face 33 to enter the seal gap 20, so the inflow of lubricating oil into the seal gap 20 can be suppressed, and ultimately the accumulation of lubricating oil at the bottom of the seal gap 20 can be suppressed.

[0043] In this specification, expressions expressing relative or absolute arrangements, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," not only strictly express such arrangements, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions expressing that things are in an equal state, such as "identical," "equal," and "homogeneous," not only express a state in which there is a strict equivalence, but also express a state in which there is a tolerance or a difference to the extent that the same function is obtained. Furthermore, in this specification, expressions expressing shapes such as a rectangular shape or a cylindrical shape not only express shapes such as a rectangular shape or a cylindrical shape in the strict geometric sense, but also express shapes including concave and convex portions, chamfered portions, etc., to the extent that the same effect is obtained. Furthermore, in this specification, the expressions "comprise," "include," or "have" a component are not exclusive expressions that exclude the presence of other components.

[0044] The present disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0045] The contents of the above-described embodiments can be understood, for example, as follows.

[0046] 1) A seal structure (2) for a turbocharger according to at least one embodiment of the present disclosure is a seal structure for a turbocharger (1), comprising: a rotating member (3) including at least a rotating shaft (11) of the turbocharger (1) and a rotating wheel (12) provided on one end side of the rotating shaft (11); a stationary member (4) including at least a housing (14) that accommodates the rotating member (3); a bearing (13) that rotatably supports the rotating shaft (11); and a seal member (5) provided in a seal gap (20) formed between the rotating member (3) and the stationary member (4), the seal gap (20) communicating between a first space (21) in which the rotating wheel (12) is accommodated and a second space (22) in which the bearing (13) is accommodated, wherein the rotating member (3) includes at least a rotating-side outer peripheral surface (31) that defines the seal gap (20), The stationary member (4) includes a stationary-side inner circumferential surface (41) that defines the sealing gap (20), and a stationary-side end face (43) that extends from an edge (42) of the stationary-side inner circumferential surface (41) on the second space (22) side along the radial direction of the rotating shaft (11), and the stationary-side end face (43) includes a slope (6) that is provided in a predetermined circumferential range (CR) below the axis (LA) of the rotating shaft (11), and that inclines toward the second space (22) side in the axial direction of the rotating shaft (11) as it extends downward from the edge (42) of the stationary-side inner circumferential surface (41) on the second space (22) side.

[0047] According to the configuration of 1) above, the slope (6) provided in a predetermined circumferential range (CR) below the axis (LA) of the rotating shaft (11) on the stationary side end face (43) allows the lubricating oil to be discharged from the lower part of the seal gap (20), thereby preventing the lubricating oil from accumulating in the lower part of the seal gap (20). The seal structure (2) for the turbocharger described in 1) above prevents the lubricating oil from accumulating in the lower part of the seal gap (20), thereby preventing the lubricating oil from leaking beyond the seal member (5) provided in the seal gap (20) to the first space (21) side (the side where the rotating wheel 12 is located).

[0048] 2) In some embodiments, in the seal structure (2) for a turbocharger described in 1) above, the slope (6) is formed to include a position (P1) vertically below the axis (LA) of the rotating shaft (11).

[0049] According to the configuration 2), by forming the slope (6) so as to include a position (P1) vertically below the axis (LA) of the rotating shaft (11), the lubricating oil can be directly discharged from a lower region of the seal gap (20) including the position (P1) vertically below the axis (LA) of the rotating shaft (11), which is a portion where the lubricating oil accumulates in the seal gap (20), to the slope (6). Therefore, the slope (6) including the vertically below position (P1) can more effectively discharge the lubricating oil from the lower portion of the seal gap (20) to the slope (6) than a slope (6) that does not include the vertically below position (P1).

[0050] 3) In some embodiments, in the seal structure (2) for a turbocharger described in 2) above, the slope (6) is inclined in the circumferential direction from both ends (61, 62) of the circumferential range (CR) toward the vertically downward position (P1).

[0051] According to the configuration of 3), the slope (6) is provided with a circumferential inclination from both ends (61, 62) in the circumferential range (CR) toward the vertically downward position (P1), thereby allowing the lubricating oil guided from the seal gap (20) to the slope (6) to flow toward the vertically downward position (P1). As a result, the flow of lubricating oil formed on the slope (6) collects the lubricating oil, and the movement of the lubricating oil along the inclination of the slope (6) due to its own weight is promoted, thereby improving the efficiency of discharging the lubricating oil via the slope (6).

[0052] 4) In some embodiments, in the seal structure (7) for a turbocharger according to any one of 1) to 3), the circumferential range (CR) of the slope (6) is set to a range of 60° or more and 120° or less.

[0053] If the circumferential range (CR) of the slope (6) is made too small, the effect of discharging the lubricating oil from the seal gap (20) via the slope (6) will be reduced. Also, if the circumferential range (CR) of the slope (6) is made too large, an excess slope (6) will be formed in the circumferential range (CR) such that the lubricating oil will fall by gravity without passing through the slope (6). According to the configuration of 4) above, by setting the circumferential range (CR) of the slope (6) in the range of 60° or more and 120° or less, the effect of discharging the lubricating oil from the seal gap (20) via the slope (6) can be improved compared to when the circumferential range (CR) of the slope (6) is set to less than 60°. Furthermore, by setting the circumferential range (CR) of the slope (6) to a range of 60° or more and 120° or less, it is possible to prevent excess slopes (6) from being formed compared to when the circumferential range (CR) of the slope (6) is set to a range exceeding 120°, and the work required to form the slopes (6) can be shortened.

[0054] 5) In some embodiments, in the seal structure (2) for a turbocharger described in 4) above, the circumferential range (CR) of the slope (6) is set to a range of 85° or more and 95° or less.

[0055] According to the configuration of 5) above, by setting the circumferential range (CR) of the slope (6) in the range of 85° or more and 95° or less, it is possible to effectively prevent the formation of an excess slope (6) while suppressing a decrease in the effect of discharging lubricating oil from the seal gap (20) via the slope (6).

[0056] 6) In some embodiments, in the seal structure (2) for a turbocharger described in any of 1) to 5) above, the rotating member (3) further includes a rotation-side end face (33) extending along the radial direction of the rotating shaft (11) from an edge (32) on the second space (22) side of the rotating-side outer peripheral surface (31), and at a position (P1) vertically below the axis (LA) of the rotating shaft (11), the edge (42) on the second space (22) side of the stationary-side inner peripheral surface (41) is located closer to the first space (21) than the edge (32) on the second space (22) side of the rotating-side outer peripheral surface (31).

[0057] According to the configuration of 6) above, at a position (P1) vertically below the axis (LA) of the rotating shaft (11), the edge (42) of the stationary-side inner peripheral surface (41) on the second space (22) side, i.e., the upper edge of the slope 6, is located closer to the first space (21) than the edge (32) of the rotating-side outer peripheral surface (31) on the second space (22) side. In this case, the shape makes it difficult for the lubricating oil flowing down the rotating-side end face (33) to enter the seal gap (20), so that the inflow of the lubricating oil into the seal gap (20) can be suppressed, and therefore, the accumulation of the lubricating oil in the lower part of the seal gap (20) can be suppressed.

[0058] REFERENCE SIGNS LIST 1 Turbocharger 2, 2A, 2B Seal structure 3 Rotating member 4 Stationary member 5 Seal member 6 Slope 11 Rotating shaft 12 Rotating wheel 12A Turbine wheel 12B Compressor wheel 13 Bearing 14 Housing 15 Sleeve 20, 20A, 20B Seal gap 20C Lower region 21, 21A, 21B First space 22 Second space 23 Lubricating oil inlet 24 Lubricating oil supply path 25 Lubricating oil outlet 31, 31A, 31B Rotating side outer peripheral surface 32 Edge 33 Rotating side end surface 41, 41A, 41B Stationary side inner peripheral surface 42 Edge 42A Slope side edge 42B Flat surface side edge 43 Stationary side end surface 43A, 43B Flat surface 44 Lower end edge 61, 62 End CR Circumferential range LA Axis P1 Vertically downward position

Claims

1. A seal structure for a turbocharger comprising: a rotating member including at least a rotating shaft of the turbocharger and a rotating wheel provided on one end side of the rotating shaft; a stationary member including at least a housing that accommodates the rotating member; a bearing that rotatably supports the rotating shaft; and a seal member provided in a seal gap formed between the rotating member and the stationary member, the seal gap communicating a first space in which the rotating wheel is accommodated and a second space in which the bearing is accommodated, wherein the rotating member includes at least a rotating side outer peripheral surface that defines the seal gap, and the stationary member includes a stationary side inner peripheral surface that defines the seal gap, and a stationary side end face that extends in a radial direction of the rotating shaft from an edge of the stationary side inner peripheral surface on the second space side, and the stationary side end face includes a slope provided in a predetermined circumferential range below the axis of the rotating shaft, and a slope that inclines toward the second space in the axial direction of the rotating shaft as it extends downward from the edge of the stationary side inner peripheral surface on the second space side.

2. The seal structure for a turbocharger according to claim 1, wherein the slope is formed so as to include a position vertically below the axis of the rotating shaft.

3. The seal structure for a turbocharger according to claim 2, wherein the slope is inclined in the circumferential direction from both ends of the circumferential range toward the vertically downward position.

4. The seal structure for a turbocharger according to any one of claims 1 to 3, wherein the circumferential range of the slope is set to a range of 60° or more and 120° or less.

5. The seal structure for a turbocharger according to claim 4, wherein the circumferential range of the slope is set to a range of 85° to 95°.

6. A sealing structure for a turbocharger as claimed in any one of claims 1 to 3, wherein the rotating member further includes a rotating-side end face extending radially of the rotating shaft from an edge of the rotating-side outer peripheral surface facing the second space, and at a position vertically below the axis of the rotating shaft, the edge of the stationary-side inner peripheral surface facing the second space is located closer to the first space than the edge of the rotating-side outer peripheral surface facing the second space.

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