Seal structure for supercharger

Abstract

This seal structure for a turbocharger comprises: a rotary member including a rotary shaft of the turbocharger and a rotary wheel provided on one end side of the rotary shaft; a stationary member including a housing that stores the rotary member; a bearing that rotatably supports the rotary shaft; and a seal member provided in a seal gap that is formed between the rotary member and the stationary member to provide communication between a first space in which the rotary wheel is stored and a second space in which the bearing is stored. The stationary member includes a stationary-side inner peripheral surface defining the seal gap, and a stationary-side end surface extending from an edge of the stationary-side inner peripheral surface on the second space side along a radial direction of the rotary shaft. The stationary member has an oil discharge groove provided on the stationary-side end surface below an axis of the rotary shaft and extending downward along a vertical direction from the edge of the stationary-side inner peripheral surface on the second space side.

Description

Technical Field

[0001] The present disclosure relates to a seal structure of a turbocharger.Background Art

[0002] A turbocharger includes a rotor (rotating body) that includes a rotary shaft, a turbine impeller attached to one side of the rotary shaft, and a compressor impeller attached to the other side of the rotary shaft, a bearing that rotatably supports a portion of the rotary shaft between the turbine impeller and the compressor impeller and a casing that accommodates the rotor and the bearing. Since the bearing of the turbocharger supports the rotary shaft that rotates at a high speed, the bearing is likely to become hot, and there is a concern that seizure may occur due to insufficient lubrication. For this reason, a lubricant is supplied to the bearing to lubricate or cool the bearing. Some turbochargers include a seal ring that seals a space between an outer surface of a rotating body, such as a rotor, and an inner surface of a stationary body, such as a casing, in order to prevent a lubricant supplied to a bearing from leaking to a compressor or a turbine (for example, see PTL 1).Citation ListPatent Literature

[0003] [PTL 1] Japanese Unexamined Patent Application Publication No. 2008-232124Summary of InventionTechnical Problem

[0004] In the turbocharger including a sealing mechanism using the seal ring, there is a concern that the lubricant may leak. Specifically, the lubricant accumulates in the space between the outer surface of the rotating body on which the seal ring is mounted and the inner surface of the stationary body, and there is a concern that the lubricant accumulated in the space may leak to a space opposite to the space with the seal ring interposed therebetween.

[0005] In view of the above circumstances, an object of at least one embodiment of the present invention is to provide a seal structure of a turbocharger that can suppress leakage of a lubricant.Solution to Problem

[0006] According to at least one embodiment of the present invention, there is provided a seal structure of a turbocharger including: a rotating member that includes at least a rotary shaft of the turbocharger and a rotating wheel provided on one end side of the rotary shaft; a stationary member that includes at least a housing accommodating the rotating member; a bearing that rotatably supports the rotary shaft; and a seal member that is provided in a seal gap which is formed between the rotating member and the stationary member and through which a first space, in which the rotating wheel is accommodated, and a second space, in which the bearing is accommodated, communicate with each other, in which the rotating member includes at least a rotating-side outer peripheral surface that defines the seal gap, the stationary member includes a stationary-side inner peripheral surface that defines the seal gap and a stationary-side end surface that extends from an edge on a side of the second space in the stationary-side inner peripheral surface along a radial direction of the rotary shaft, and the stationary member has an oil discharge groove that is provided in the stationary-side end surface below an axis line of the rotary shaft and extends downward along a vertical direction from the edge on the side of the second space in the stationary-side inner peripheral surface.Advantageous Effects of Invention

[0007] According to at least one embodiment of the present invention, a seal structure of a turbocharger that can suppress leakage of a lubricant is provided.Brief Description of Drawings

[0008] FIG. 1 is a schematic cross-sectional view showing a cross section of a turbocharger including a seal structure of the turbocharger according to an embodiment along an axis line. FIG. 2 is a schematic cross-sectional view showing a cross section of the seal structure of the turbocharger according to the embodiment along the axis line. FIG. 3 is a schematic view showing a state in which the seal structure of the turbocharger according to the embodiment is viewed from a second space side. FIG. 4 is a schematic view showing a state in which the seal structure of the turbocharger according to the embodiment is viewed from the second space side. FIG. 5 is a schematic view showing a state in which the vicinity of an oil discharge groove in the seal structure of the turbocharger according to the embodiment is viewed from above. FIG. 6 is a schematic cross-sectional view showing a cross section of a seal structure of a turbocharger according to an embodiment along an axis line. Description of Embodiments

[0009] Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, dimensions, materials, shapes, relative dispositions, and the like of components described as embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are only explanatory examples.(Turbocharger)

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

[0011] The bearing 13 is supported by the housing 14. The rotary shaft 11 is supported by the bearing 13 between the compressor wheel 12A and the turbine wheel 12B to be rotatable about an axis line LA of the rotary shaft 11.

[0012] Hereinafter, a direction in which the axis line LA of the rotary shaft 11 extends is defined as an axial direction of the rotary shaft 11 (turbocharger 1), and a direction orthogonal to the axis line LA is defined as a radial direction of the rotary shaft 11 (turbocharger 1). In the axial direction of the rotary shaft 11 (turbocharger 1), a side on which the compressor wheel 12A is located with respect to the turbine wheel 12B is referred to as a compressor side, and a side on which the turbine wheel 12B is located with respect to the compressor wheel 12A is referred to as a turbine side.

[0013] The turbine wheel 12B is configured to be rotated by the energy of an exhaust gas that has been discharged from an engine and guided to the turbine wheel 12B. The compressor wheel 12A is rotated together with the rotary shaft 11 in operative association with the rotation of the turbine wheel 12B. The turbocharger 1 is configured to compress a gas (for example, air) guided to the compressor wheel 12A by the rotation of the compressor wheel 12A to increase the density of the gas and to deliver the gas to a supply destination (for example, the engine) of the gas.(Seal Structure of Turbocharger)

[0014] FIG. 2 is a schematic cross-sectional view showing a cross section of the seal structure of the turbocharger according to the embodiment along the axis line. FIG. 2 shows a region surrounded by a dashed double-dotted line in FIG. 1. FIGS. 3 and 4 are schematic views showing a state in which the seal structure of the turbocharger according to the embodiment is viewed from a second space side. FIG. 5 is a schematic view showing a state in which the vicinity of an oil discharge groove in the seal structure of the turbocharger according to the embodiment is viewed from above. A seal structure 2 of a turbocharger according to some embodiments is a seal structure that is provided in a turbocharger 1 to suppress leakage of a lubricant in the turbocharger 1. As shown in FIG. 1, the seal structure 2 of the turbocharger includes a rotating member 3, a stationary member 4 that accommodates the rotating member 3, a seal member 5 that is provided in a seal gap 20 formed between the rotating member 3 and the stationary member 4, and the bearing 13.(Rotating Member and Stationary Member)

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

[0016] The stationary member 4 (housing 14) accommodates the rotating member 3 and the bearing 13. The seal gap 20, a first space 21 in which the rotating wheel 12 is accommodated, and a second space 22 in which the bearing 13 is accommodated are formed in the stationary member 4 (housing 14). The seal gap 20 is provided between the first space 21 and the second space 22 in the axial direction of the rotary shaft 11 and allows the first space 21 and the second space 22 to communicate with each other.

[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 outside the rotating-side outer peripheral surface 31 in the radial direction of the rotary shaft 11 and faces the rotating-side outer peripheral surface 31 with the seal gap 20, which is formed in an annular shape, interposed therebetween.

[0018] The stationary member 4 has a stationary-side end surface 43 that extends outward in the radial direction of the rotary shaft 11 from an edge 42 on the side of the second space 22 in the stationary-side inner peripheral surface 41 along the radial direction, as shown in FIG. 2. The rotating member 3 may have a rotating-side end surface 33 that extends inward in the radial direction of the rotary shaft 11 from an edge 32 on the side of the second space 22 in the rotating-side outer peripheral surface 31 along the radial direction, as shown in FIG. 2.(Seal Member)

[0019] The seal member 5 is configured to seal a space between the stationary-side inner peripheral surface 41 and the rotating-side outer peripheral surface 31. In the shown embodiment, as shown in FIG. 2, the seal 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 and has an outer peripheral surface that is in contact with the stationary-side inner peripheral surface 41 and an inner peripheral surface that is in contact with the rotating-side outer peripheral surface 31. In addition, as shown in FIGS. 1 and 2, an annular groove portion that extends along a circumferential direction of the rotary shaft 11 and is for fitting a portion of the seal member 5 may be provided in at least one of the stationary-side inner peripheral surface 41 or the rotating-side outer peripheral surface 31.(Lubricant System)

[0020] The turbocharger 1 is configured such that a lubricant flows into the bearing 13 or the second space 22 in which the bearing 13 is accommodated. In the embodiment shown in FIG. 1, a lubricant introduction port 23 for introducing the lubricant into the housing 14, a lubricant supply path 24 for guiding the lubricant from the lubricant introduction port 23 to the bearing 13, and a lubricant discharge port 25 for discharging the lubricant to the outside of the housing 14 are formed in the housing 14. The lubricant supply path 24 is a flow path which is defined by an inner wall surface of the housing 14 and through which the lubricant introduction port 23 and the second space 22 communicate with each other. The lubricant discharge port 25 is provided below the second space 22 and communicates with a lower portion of the second space 22.

[0021] The lubricant introduced into the housing 14 through the lubricant introduction port 23 is guided to the bearing 13 through the lubricant supply path 24. Most of the lubricant guided to the bearing 13 flows down in the second space 22 and is discharged to the outside of the housing 14 through the lubricant discharge port 25. A portion of the lubricant guided to the bearing 13 may flow into the seal gap 20.

[0022] The seal structure 2 of the turbocharger 1 according to some embodiments includes the rotating member 3, the stationary member 4, the bearing 13, and the seal member 5 provided in the seal gap 20. The stationary member 4 includes the stationary-side inner peripheral surface 41 and the stationary-side end surface 43. As shown in FIGS. 2 to 4, the stationary-side end surface 43 has an oil discharge groove 6 that is provided in the stationary-side end surface 43 below the axis line LA of the rotary shaft 11. The oil discharge groove 6 extends downward from the edge 42 on the side of the second space 22 in the stationary-side inner peripheral surface 41 along a vertical direction. Hereinafter, a direction orthogonal to the extending direction of the oil discharge groove 6 is referred to as a width direction of the oil discharge groove 6. The width direction of the oil discharge groove 6 extends along a horizontal direction orthogonal to the axis line LA of the rotary shaft 11.

[0023] As shown in FIGS. 2 to 5, the stationary-side end surface 43 further has a flat surface 43A that is provided in a region other than the region in which the oil discharge groove 6 is formed. The flat surface 43A extends outward in the radial direction of the rotary shaft 11 from the edge 42 on the side of the second space 22 in the stationary-side inner peripheral surface 41 along the radial direction. As shown in FIG. 5, in the edge 42 on the side of the second space 22 in the stationary-side inner peripheral surface 41, an oil-discharge-groove-side edge 42A (an upper edge of the oil discharge groove 6) that is continuous with the oil discharge groove 6 has a concave shape (in the shown example, a U-shape with pointed corners) that is recessed from a flat-surface-side edge 42B continuous with the flat surface 43A (an inner peripheral edge continuous with the stationary-side inner peripheral surface 41 of the flat surface 43A) to the first space 21 in the axial direction of the rotary shaft 11.

[0024] The lubricant that has flowed into the seal gap 20 is accumulated in the lower portion of the seal gap 20. At least a portion of the lubricant accumulated in the lower portion of the seal gap 20 flows down along the oil discharge groove 6 and is discharged to the second space 22.

[0025] According to the above-described configuration, the lubricant can be discharged from the lower portion of the seal gap 20 by the oil discharge groove 6 provided in the stationary-side end surface 43 below the axis line LA of the rotary shaft 11. Therefore, it is possible to suppress the accumulation of the lubricant in the lower portion of the seal gap 20. The seal structure 2 of the turbocharger suppresses the accumulation of the lubricant in the lower portion of the seal gap 20, which makes it possible to suppress the leakage of the lubricant from the seal member 5 provided in the seal gap 20 to the first space 21 (the side on which the rotating wheel 12 is located).

[0026] In some embodiments, as shown in FIG. 1, a seal structure 2A (2) of a turbocharger is for suppressing the leakage of the lubricant from the second space 22 to a first space 21A (21) in which the compressor wheel 12A is accommodated. The rotating wheel 12 of the seal structure 2A of the turbocharger is the compressor wheel 12A. As shown in FIG. 1, the first space 21A, which is a space in which the compressor wheel 12A is accommodated, and a seal gap 20A (20) are provided closer to the compressor than the second space 22, in which the bearing 13 is accommodated, in the axial direction of the rotary shaft 11.

[0027] The rotating-side outer peripheral surface 31A (31) may be, for example, an outer peripheral surface of an annular sleeve 15 that is included in the turbocharger 1 as shown in FIG. 1. The sleeve 15 is attached to the rotary shaft 11 between the compressor wheel 12A (rotating wheel 12) and the bearing 13 in the axial direction of the rotary shaft 11 to cover the outer periphery of the rotary shaft 11. The rotating member 3 may further include the sleeve 15. A stationary-side inner peripheral surface 41A (41) may be an inner wall surface of the housing 14 that faces the outer peripheral surface of the sleeve 15 with the seal gap 20B interposed therebetween.

[0028] In some embodiments, as shown in FIG. 1, a seal structure 2B (2) of a turbocharger is for suppressing the leakage of the lubricant from the second space 22 to a first space 21B (21) in which the turbine wheel 12B is accommodated. The rotating wheel 12 of the seal structure 2B of the turbocharger is the turbine wheel 12B. As shown in FIG. 1, the first space 21B, which is a space in which the turbine wheel 12B is accommodated, and the seal gap 20B (20) are provided closer to the turbine than the second space 22, in which the bearing 13 is accommodated, in the axial direction of the rotary shaft 11.

[0029] A rotating-side outer peripheral surface 31B (31) may be, for example, an outer peripheral surface of a boss portion that protrudes from a back surface of the turbine wheel 12B as shown in FIG. 1. A 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 boss portion of the turbine wheel 12B with the seal gap 20B interposed therebetween. In addition, the rotating-side outer peripheral surface 31 may be an outer peripheral surface of the rotary shaft 11.

[0030] In addition, the turbocharger 1 may include both the seal structures 2A and 2B of the turbocharger. That is, each of an end surface of the stationary-side inner peripheral surface 41A that is continuous with the turbine and an end surface of the stationary-side inner peripheral surface 41B that is continuous with the compressor may be the stationary-side end surface 43 including the oil discharge groove 6.

[0031] As shown in FIGS. 3 and 4, an angular position θ is defined such that a position vertically below the axis line LA of the rotary shaft 11 is 0° and the angle increases toward a rotation direction of the rotary shaft 11. In some embodiments, the oil discharge groove 6 includes a pair of groove wall surfaces 62 and 63 that face each other with a gap therebetween in the width direction of the oil discharge groove 6. It is preferable that one groove wall surface 62 of the pair of groove wall surfaces 62 and 63 is provided with an upper end 64 that is continuous with the stationary-side inner peripheral surface 41 in a range in which the angular position θ is equal to or greater than +45° and equal to or less than +95°. It is preferable that the other groove wall surface 63 of the pair of groove wall surfaces 62 and 63 is provided with an upper end 65 that is continuous with the stationary-side inner peripheral surface 41 in a range in which the angular position θ is equal to or greater than -95° and equal to or less than -45°.

[0032] In the embodiment shown in FIG. 3, the upper end 64 of the one groove wall surface 62 is provided at a position where the angular position θ is +45°, and the upper end 65 of the other groove wall surface 63 is provided at a position where the angular position θ is -45°.

[0033] According to the above-described configuration, the upper end 64 of the one groove wall surface 62 is provided in the range in which the angular position θ is equal to or greater than +45° and equal to or less than +95°, and the upper end 65 of the other groove wall surface 63 is provided in the range in which the angular position θ is equal to or greater than -95° and equal to or less than -45°. Therefore, it is possible to reduce an inclination angle with respect to the vertical direction at the connection position of the stationary-side inner peripheral surface 41 with each of the one groove wall surface 62 and the other groove wall surface 63. As a result, it is possible to guide the lubricant flowing down along the stationary-side inner peripheral surface 41 to the oil discharge groove and thus to suppress the accumulation of the lubricant on the stationary-side inner peripheral surface 41. In addition, according to the above-described configuration, since the length of the oil discharge groove 6 in the width direction is large, the flow of the lubricant from the lower portion of the seal gap 20 into the oil discharge groove 6 is promoted.

[0034] In the shown embodiment, the oil discharge groove 6 further has a groove bottom surface 61 that connects the ends of the pair of groove wall surfaces 62 and 63 on the side of the first space 21. The groove bottom surface 61 of the oil discharge groove 6 is formed to include the position where the angular position θ is 0°. The formation of the oil discharge groove 6 to include the position where the angular position θ is 0° makes it possible to directly discharge the lubricant from the lower portion of the seal gap 20, in which the lubricant is accumulated, to the oil discharge groove 6.

[0035] As shown in FIG. 4, it is more preferable that the upper end 64 of the one groove wall surface 62 is provided at a position where the angular position θ is equal to or greater than +85° and equal to or less than +95°. It is more preferable that the upper end 65 of the other groove wall surface 63 is provided at a position where the angular position θ is equal to or greater than -95° and equal to or less than -85°. In the embodiment shown in FIG. 4, the upper end 64 of the one groove wall surface 62 is provided at a position where the angular position θ is +90°, and the upper end 65 of the other groove wall surface 63 is provided at a position where the angular position θ is -90°.

[0036] According to the above-described configuration, the upper end 64 of one groove wall surface 62 is provided in the range in which the angular position θ is equal to or greater than +85° and equal to or less than +95°, and the upper end 65 of the other groove wall surface 63 is provided in the range in which the angular position θ is equal to or greater than -95° and equal to or less than -85°. Therefore, it is possible to reduce the inclination angle with respect to the vertical direction at the connection position of the stationary-side inner peripheral surface 41 with each of the one groove wall surface 62 and the other groove wall surface 63. As a result, it is possible to effectively guide the lubricant flowing down along the stationary-side inner peripheral surface 41 to the oil discharge groove 6 and thus to effectively suppress the accumulation of the lubricant on the stationary-side inner peripheral surface 41.

[0037] In some embodiments, as shown in FIG. 4, when the length of the oil discharge groove 6 in the width direction is L1 and the diameter of the stationary-side inner peripheral surface 41 is L2, the oil discharge groove 6 satisfies a condition of 0.95 × L2 ≤ L1 ≤ 1.05 × L2. In the shown embodiment, the length L1 of the oil discharge groove 6 in the width direction is constant. However, in another embodiment, the oil discharge groove 6 may be configured such that the length of the oil discharge groove 6 in the width direction increases as the oil discharge groove 6 extends downward or may be configured such that the length of the oil discharge groove 6 in the width direction decreases as the oil discharge groove 6 extends downward. In addition, when the length of the oil discharge groove 6 in the width direction is not constant, the length of the upper edge of the oil discharge groove 6 (an edge continuous with the oil-discharge-groove-side edge 42A) in the width direction may be used as the length L1.

[0038] According to the above-described configuration, the length L1 of the oil discharge groove 6 in the width direction is equal to the diameter L2 of the stationary-side inner peripheral surface 41, which makes it possible to effectively guide the lubricant flowing down along the stationary-side inner peripheral surface 41 to the oil discharge groove 6 and to effectively suppress the accumulation of the lubricant on the stationary-side inner peripheral surface 41. In addition, the length L1 of the oil discharge groove 6 in the width direction is equal to the diameter L2 of the stationary-side inner peripheral surface 41, which makes it possible to enhance the discharge performance of the lubricant from the oil discharge groove 6.

[0039] In some embodiments, as shown in FIG. 2, the groove bottom surface 61 is located closer to the first space 21 than the edge 32 on the side of the second space 22 in the rotating-side outer peripheral surface 31 below the axis line LA of the rotary shaft 11.

[0040] According to the above-described configuration, the groove bottom surface 61 is located closer to the first space 21 than the edge 32 on the side of the second space 22 in the rotating-side outer peripheral surface 31 below the axis line LA of the rotary shaft 11. In this case, the seal structure has a shape in which the lubricant flowing down along the rotating-side end surface 33 is less likely to enter the seal gap 20. Therefore, it is possible to suppress the flow of the lubricant into the seal gap 20 and to suppress the accumulation of the lubricant in the lower portion of the seal gap 20.

[0041] FIG. 6 is a schematic cross-sectional view showing a cross section of a seal structure of a turbocharger according to an embodiment along an axis line. FIG. 6 shows a region surrounded by a dashed double-dotted line in FIG. 1. In some embodiments, as shown in FIG. 6, the stationary-side end surface 43 has the oil discharge groove 6 and a flat surface 43B that is provided in a region other than the region in which the oil discharge groove 6 is formed. Similarly to the flat surface 43A, the flat surface 43B extends outward in the radial direction of the rotary shaft 11 from the edge 42 on the side of the second space 22 in the stationary-side inner peripheral surface 41 along the radial direction. The flat surface 43B is located closer to the first space 21 than the edge 32 on the side of the second space 22 in the rotating-side outer peripheral surface 31 below the axis line LA of the rotary shaft 11. In this case, the seal structure has a shape in which the lubricant flowing down along the rotating-side end surface 33 is less likely to enter the seal gap 20. Therefore, it is possible to suppress the flow of the lubricant into the seal gap 20 and to suppress the accumulation of the lubricant in the lower portion of the seal gap 20.

[0042] A protrusion member (not shown) that suppresses the flow of the lubricant from the second space 22 into the seal gap 20 may be provided on the stationary-side inner peripheral surface 41. The protrusion member protrudes from the stationary-side inner peripheral surface 41 to the inside in the radial direction of the rotary shaft 11 and extends along the circumferential direction of the rotary shaft 11.

[0043] In this specification, an expression representing a relative or absolute disposition, such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric", or "coaxial" does not strictly represent only the disposition, but also represents a state of being relatively displaced with a tolerance or a sufficient angle or distance to obtain the same function.

[0044] For example, expressions, such as "identical", "equal", and "homogeneous", representing that things are in an equal state do not strictly represent only the equal state, but also represent a state in which there is a tolerance or a sufficient difference to obtain the same function.

[0045] In addition, in this specification, an expression representing a shape, such as a quadrangular shape or a cylindrical shape, does not represent only a shape, such as a quadrangular shape or a cylindrical shape, in a strictly geometric sense, but also represents a shape including an undulating portion, a chamfered portion, or the like within a range in which the same effect is obtained.

[0046] In addition, in this specification, an expression such as "comprising", "including", or "having" one component is not an exclusive expression excluding the presence of other components.

[0047] The present disclosure is not limited to the above-described embodiments and also includes modifications of the above-described embodiments and appropriate combinations of the modifications.

[0048] The contents described in some embodiments described above are understood as follows, for example.

[0049] 1) A seal structure (2) of a turbocharger (1) according to at least one embodiment of the present disclosure includes: a rotating member (3) that includes at least a rotary shaft (11) of the turbocharger (1) and a rotating wheel (12) provided on one end side of the rotary shaft (11); a stationary member (4) that includes at least a housing (14) accommodating the rotating member (3); a bearing (13) that rotatably supports the rotary shaft (11); and a seal member (5) that is provided in a seal gap (20) which is formed between the rotating member (3) and the stationary member (4) and through which a first space (21), in which the rotating wheel (12) is accommodated, and a second space (22), in which the bearing (13) is accommodated, communicate with each other, in which 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 peripheral surface (41) that defines the seal gap (20) and a stationary-side end surface (43) that extends from an edge (42) on a side of the second space (22) in the stationary-side inner peripheral surface (41) along a radial direction of the rotary shaft (11), and the stationary-side end surface (43) has an oil discharge groove (6) that is provided in the stationary-side end surface (43) below an axis line (LA) of the rotary shaft (11) and extends downward along a vertical direction from the edge (42) on the side of the second space (22) in the stationary-side inner peripheral surface (41).

[0050] According to the configuration of 1), the lubricant can be discharged from the lower portion of the seal gap (20) by the oil discharge groove (6) provided in the stationary-side end surface (43) below the axis line (LA) of the rotary shaft (11). Therefore, it is possible to suppress the accumulation of the lubricant in the lower portion of the seal gap (20). In the seal structure (2) of the turbocharger according to 1), since the accumulation of the lubricant in the lower portion of the seal gap (20) is suppressed, it is possible to suppress the leakage of the lubricant from the seal member (5) provided in the seal gap (20) to the first space (21) (the side on which the rotating wheel 12 is located).

[0051] 2) In some embodiments, in the seal structure (6) of the turbocharger according to 1), the oil discharge groove (6) has a pair of groove wall surfaces (62, 63) that face each other with a gap therebetween in a width direction of the oil discharge groove (6), and when an angular position (θ) is defined such that a position vertically below the axis line (LA) of the rotary shaft (11) is 0° and an angle increases toward a rotation direction of the rotary shaft (11), an upper end (64) of one groove wall surface (62) of the pair of groove wall surfaces (62, 63) is provided in a range in which the angular position (θ) is equal to or greater than +45° and equal to or less than +95°, and an upper end (65) of the other groove wall surface (63) of the pair of groove wall surfaces (62, 63) is provided in a range in which the angular position (θ) is equal to or greater than -95° and equal to or less than -45°.

[0052] According to the configuration of 2), the upper end (64) of the one groove wall surface (62) is provided in the range in which the angular position (θ) is equal to or greater than +45° and equal to or less than +95°, and the upper end (65) of the other groove wall surface (63) is provided in the range in which the angular position (θ) is equal to or greater than -95° and equal to or less than -45°. Therefore, it is possible to reduce the inclination angle with respect to the vertical direction at the connection position of the stationary-side inner peripheral surface (41) with each of the one groove wall surface (62) and the other groove wall surface (63). As a result, it is possible to guide the lubricant flowing down along the stationary-side inner peripheral surface (41) to the oil discharge groove and thus to suppress the accumulation of the lubricant on the stationary-side inner peripheral surface (41).

[0053] 3) In some embodiments, in the seal structure (2) of the turbocharger according to 2), the upper end (64) of the one groove wall surface (62) is provided at a position where the angular position (θ) is equal to or greater than +85° and equal to or less than +95°, and the upper end (65) of the other groove wall surface (63) is provided at a position where the angular position (θ) is equal to or greater than -95° and equal to or less than -85°.

[0054] According to the configuration of 3), the upper end (64) of the one groove wall surface (62) is provided in the range in which the angular position is equal to or greater than +85° and equal to or less than +95°, and the upper end (65) of the other groove wall surface (63) is provided in the range in which the angular position (θ) is equal to or greater than -95° and equal to or less than -85°. Therefore, it is possible to reduce the inclination angle with respect to the vertical direction at the connection position of the stationary-side inner peripheral surface (41). As a result, it is possible to effectively guide the lubricant flowing down along the stationary-side inner peripheral surface (41) to the oil discharge groove (6) and thus to effectively suppress the accumulation of the lubricant on the stationary-side inner peripheral surface (41).

[0055] 4) In some embodiments, in the seal structure (2) of the turbocharger according to 3), when a length of the oil discharge groove (6) in the width direction is L1 and a diameter of the stationary-side inner peripheral surface (41) of the stationary member (4) is L2, the oil discharge groove (6) satisfies a condition of 0.95 × L2 ≤ L1 ≤ 1.05 × L2.

[0056] According to the configuration of 4), the length L1 of the oil discharge groove (6) in the width direction is equal to the diameter L2 of the stationary-side inner peripheral surface (41), which makes it possible to effectively guide the lubricant flowing down along the stationary-side inner peripheral surface (41) to the oil discharge groove (6) and thus to effectively suppress the accumulation of the lubricant on the stationary-side inner peripheral surface (41). In addition, the length L1 of the oil discharge groove (6) in the width direction is equal to the diameter L2 of the stationary-side inner peripheral surface (41), which makes it possible to enhance the discharge performance of the lubricant from the oil discharge groove (6).

[0057] 5) In some embodiments, in the seal structure (2) of the turbocharger according to any one of 2) to 4), the oil discharge groove (6) further has a groove bottom surface (61) that connects edges on a side of the first space (21) in the pair of groove wall surfaces (62, 63), and the groove bottom surface (61) is located closer to the first space (21) than the edge (32) on the side of the second space (22) in the rotating-side outer peripheral surface (31) below the axis line (LA) of the rotary shaft (11).

[0058] According to the configuration of 5), the groove bottom surface (61) is located closer to the first space (21) than the edge (32) on the side of the second space (22) in the rotating-side outer peripheral surface (31) below the axis line (LA) of the rotary shaft (11). In this case, since the seal structure (2) has a shape in which the lubricant flowing down along the rotating-side end surface (33) is less likely to enter the seal gap (20), it is possible to suppress the flow of the lubricant into the seal gap (20) and to suppress the accumulation of the lubricant in the lower portion of the seal gap (20).Reference Signs List

[0059] 1: Turbocharger 2, 2A, 2B: Seal structure 3: Rotating member 4: Stationary member 5: Seal member 6: Oil discharge groove 11: Rotary shaft 12: Rotating wheel 12A: Compressor wheel 12B: Turbine wheel 13: Bearing 14: Housing 15: Sleeve 20, 20A, 20B: Seal gap 21, 21A, 21B: First space 22: Second space 23: Lubricant introduction port 24: Lubricant supply path 25: Lubricant discharge port 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: Oil-discharge-groove-side edge 42B: Flat-surface-side edge 43: Stationary-side end surface 43A, 43B: Flat surface 44: Lower edge 61: Groove bottom surface 62, 63: Groove wall surface 64, 65: Upper end LA: Axis line θ: Angular position

Examples

Embodiment Construction

[0009]Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, dimensions, materials, shapes, relative dispositions, and the like of components described as embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are only explanatory examples.

(Turbocharger)

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

[0011]The bearing 13 is supp...

Technical Field

[0001] The present disclosure relates to a seal structure of a turbocharger.Background Art

[0002] A turbocharger includes a rotor (rotating body) that includes a rotary shaft, a turbine impeller attached to one side of the rotary shaft, and a compressor impeller attached to the other side of the rotary shaft, a bearing that rotatably supports a portion of the rotary shaft between the turbine impeller and the compressor impeller and a casing that accommodates the rotor and the bearing. Since the bearing of the turbocharger supports the rotary shaft that rotates at a high speed, the bearing is likely to become hot, and there is a concern that seizure may occur due to insufficient lubrication. For this reason, a lubricant is supplied to the bearing to lubricate or cool the bearing. Some turbochargers include a seal ring that seals a space between an outer surface of a rotating body, such as a rotor, and an inner surface of a stationary body, such as a casing, in order to prevent a lubricant supplied to a bearing from leaking to a compressor or a turbine (for example, see PTL 1).Citation ListPatent Literature

[0003] [PTL 1] Japanese Unexamined Patent Application Publication No. 2008-232124Summary of InventionTechnical Problem

[0004] In the turbocharger including a sealing mechanism using the seal ring, there is a concern that the lubricant may leak. Specifically, the lubricant accumulates in the space between the outer surface of the rotating body on which the seal ring is mounted and the inner surface of the stationary body, and there is a concern that the lubricant accumulated in the space may leak to a space opposite to the space with the seal ring interposed therebetween.

[0005] In view of the above circumstances, an object of at least one embodiment of the present invention is to provide a seal structure of a turbocharger that can suppress leakage of a lubricant.Solution to Problem

[0006] According to at least one embodiment of the present invention, there is provided a seal structure of a turbocharger including: a rotating member that includes at least a rotary shaft of the turbocharger and a rotating wheel provided on one end side of the rotary shaft; a stationary member that includes at least a housing accommodating the rotating member; a bearing that rotatably supports the rotary shaft; and a seal member that is provided in a seal gap which is formed between the rotating member and the stationary member and through which a first space, in which the rotating wheel is accommodated, and a second space, in which the bearing is accommodated, communicate with each other, in which the rotating member includes at least a rotating-side outer peripheral surface that defines the seal gap, the stationary member includes a stationary-side inner peripheral surface that defines the seal gap and a stationary-side end surface that extends from an edge on a side of the second space in the stationary-side inner peripheral surface along a radial direction of the rotary shaft, and the stationary member has an oil discharge groove that is provided in the stationary-side end surface below an axis line of the rotary shaft and extends downward along a vertical direction from the edge on the side of the second space in the stationary-side inner peripheral surface.Advantageous Effects of Invention

[0007] According to at least one embodiment of the present invention, a seal structure of a turbocharger that can suppress leakage of a lubricant is provided.Brief Description of Drawings

[0008] FIG. 1 is a schematic cross-sectional view showing a cross section of a turbocharger including a seal structure of the turbocharger according to an embodiment along an axis line. FIG. 2 is a schematic cross-sectional view showing a cross section of the seal structure of the turbocharger according to the embodiment along the axis line. FIG. 3 is a schematic view showing a state in which the seal structure of the turbocharger according to the embodiment is viewed from a second space side. FIG. 4 is a schematic view showing a state in which the seal structure of the turbocharger according to the embodiment is viewed from the second space side. FIG. 5 is a schematic view showing a state in which the vicinity of an oil discharge groove in the seal structure of the turbocharger according to the embodiment is viewed from above. FIG. 6 is a schematic cross-sectional view showing a cross section of a seal structure of a turbocharger according to an embodiment along an axis line. Description of Embodiments

[0009] Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, dimensions, materials, shapes, relative dispositions, and the like of components described as embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are only explanatory examples.(Turbocharger)

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

[0011] The bearing 13 is supported by the housing 14. The rotary shaft 11 is supported by the bearing 13 between the compressor wheel 12A and the turbine wheel 12B to be rotatable about an axis line LA of the rotary shaft 11.

[0012] Hereinafter, a direction in which the axis line LA of the rotary shaft 11 extends is defined as an axial direction of the rotary shaft 11 (turbocharger 1), and a direction orthogonal to the axis line LA is defined as a radial direction of the rotary shaft 11 (turbocharger 1). In the axial direction of the rotary shaft 11 (turbocharger 1), a side on which the compressor wheel 12A is located with respect to the turbine wheel 12B is referred to as a compressor side, and a side on which the turbine wheel 12B is located with respect to the compressor wheel 12A is referred to as a turbine side.

[0013] The turbine wheel 12B is configured to be rotated by the energy of an exhaust gas that has been discharged from an engine and guided to the turbine wheel 12B. The compressor wheel 12A is rotated together with the rotary shaft 11 in operative association with the rotation of the turbine wheel 12B. The turbocharger 1 is configured to compress a gas (for example, air) guided to the compressor wheel 12A by the rotation of the compressor wheel 12A to increase the density of the gas and to deliver the gas to a supply destination (for example, the engine) of the gas.(Seal Structure of Turbocharger)

[0014] FIG. 2 is a schematic cross-sectional view showing a cross section of the seal structure of the turbocharger according to the embodiment along the axis line. FIG. 2 shows a region surrounded by a dashed double-dotted line in FIG. 1. FIGS. 3 and 4 are schematic views showing a state in which the seal structure of the turbocharger according to the embodiment is viewed from a second space side. FIG. 5 is a schematic view showing a state in which the vicinity of an oil discharge groove in the seal structure of the turbocharger according to the embodiment is viewed from above. A seal structure 2 of a turbocharger according to some embodiments is a seal structure that is provided in a turbocharger 1 to suppress leakage of a lubricant in the turbocharger 1. As shown in FIG. 1, the seal structure 2 of the turbocharger includes a rotating member 3, a stationary member 4 that accommodates the rotating member 3, a seal member 5 that is provided in a seal gap 20 formed between the rotating member 3 and the stationary member 4, and the bearing 13.(Rotating Member and Stationary Member)

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

[0016] The stationary member 4 (housing 14) accommodates the rotating member 3 and the bearing 13. The seal gap 20, a first space 21 in which the rotating wheel 12 is accommodated, and a second space 22 in which the bearing 13 is accommodated are formed in the stationary member 4 (housing 14). The seal gap 20 is provided between the first space 21 and the second space 22 in the axial direction of the rotary shaft 11 and allows the first space 21 and the second space 22 to communicate with each other.

[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 outside the rotating-side outer peripheral surface 31 in the radial direction of the rotary shaft 11 and faces the rotating-side outer peripheral surface 31 with the seal gap 20, which is formed in an annular shape, interposed therebetween.

[0018] The stationary member 4 has a stationary-side end surface 43 that extends outward in the radial direction of the rotary shaft 11 from an edge 42 on the side of the second space 22 in the stationary-side inner peripheral surface 41 along the radial direction, as shown in FIG. 2. The rotating member 3 may have a rotating-side end surface 33 that extends inward in the radial direction of the rotary shaft 11 from an edge 32 on the side of the second space 22 in the rotating-side outer peripheral surface 31 along the radial direction, as shown in FIG. 2.(Seal Member)

[0019] The seal member 5 is configured to seal a space between the stationary-side inner peripheral surface 41 and the rotating-side outer peripheral surface 31. In the shown embodiment, as shown in FIG. 2, the seal 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 and has an outer peripheral surface that is in contact with the stationary-side inner peripheral surface 41 and an inner peripheral surface that is in contact with the rotating-side outer peripheral surface 31. In addition, as shown in FIGS. 1 and 2, an annular groove portion that extends along a circumferential direction of the rotary shaft 11 and is for fitting a portion of the seal member 5 may be provided in at least one of the stationary-side inner peripheral surface 41 or the rotating-side outer peripheral surface 31.(Lubricant System)

[0020] The turbocharger 1 is configured such that a lubricant flows into the bearing 13 or the second space 22 in which the bearing 13 is accommodated. In the embodiment shown in FIG. 1, a lubricant introduction port 23 for introducing the lubricant into the housing 14, a lubricant supply path 24 for guiding the lubricant from the lubricant introduction port 23 to the bearing 13, and a lubricant discharge port 25 for discharging the lubricant to the outside of the housing 14 are formed in the housing 14. The lubricant supply path 24 is a flow path which is defined by an inner wall surface of the housing 14 and through which the lubricant introduction port 23 and the second space 22 communicate with each other. The lubricant discharge port 25 is provided below the second space 22 and communicates with a lower portion of the second space 22.

[0021] The lubricant introduced into the housing 14 through the lubricant introduction port 23 is guided to the bearing 13 through the lubricant supply path 24. Most of the lubricant guided to the bearing 13 flows down in the second space 22 and is discharged to the outside of the housing 14 through the lubricant discharge port 25. A portion of the lubricant guided to the bearing 13 may flow into the seal gap 20.

[0022] The seal structure 2 of the turbocharger 1 according to some embodiments includes the rotating member 3, the stationary member 4, the bearing 13, and the seal member 5 provided in the seal gap 20. The stationary member 4 includes the stationary-side inner peripheral surface 41 and the stationary-side end surface 43. As shown in FIGS. 2 to 4, the stationary-side end surface 43 has an oil discharge groove 6 that is provided in the stationary-side end surface 43 below the axis line LA of the rotary shaft 11. The oil discharge groove 6 extends downward from the edge 42 on the side of the second space 22 in the stationary-side inner peripheral surface 41 along a vertical direction. Hereinafter, a direction orthogonal to the extending direction of the oil discharge groove 6 is referred to as a width direction of the oil discharge groove 6. The width direction of the oil discharge groove 6 extends along a horizontal direction orthogonal to the axis line LA of the rotary shaft 11.

[0023] As shown in FIGS. 2 to 5, the stationary-side end surface 43 further has a flat surface 43A that is provided in a region other than the region in which the oil discharge groove 6 is formed. The flat surface 43A extends outward in the radial direction of the rotary shaft 11 from the edge 42 on the side of the second space 22 in the stationary-side inner peripheral surface 41 along the radial direction. As shown in FIG. 5, in the edge 42 on the side of the second space 22 in the stationary-side inner peripheral surface 41, an oil-discharge-groove-side edge 42A (an upper edge of the oil discharge groove 6) that is continuous with the oil discharge groove 6 has a concave shape (in the shown example, a U-shape with pointed corners) that is recessed from a flat-surface-side edge 42B continuous with the flat surface 43A (an inner peripheral edge continuous with the stationary-side inner peripheral surface 41 of the flat surface 43A) to the first space 21 in the axial direction of the rotary shaft 11.

[0024] The lubricant that has flowed into the seal gap 20 is accumulated in the lower portion of the seal gap 20. At least a portion of the lubricant accumulated in the lower portion of the seal gap 20 flows down along the oil discharge groove 6 and is discharged to the second space 22.

[0025] According to the above-described configuration, the lubricant can be discharged from the lower portion of the seal gap 20 by the oil discharge groove 6 provided in the stationary-side end surface 43 below the axis line LA of the rotary shaft 11. Therefore, it is possible to suppress the accumulation of the lubricant in the lower portion of the seal gap 20. The seal structure 2 of the turbocharger suppresses the accumulation of the lubricant in the lower portion of the seal gap 20, which makes it possible to suppress the leakage of the lubricant from the seal member 5 provided in the seal gap 20 to the first space 21 (the side on which the rotating wheel 12 is located).

[0026] In some embodiments, as shown in FIG. 1, a seal structure 2A (2) of a turbocharger is for suppressing the leakage of the lubricant from the second space 22 to a first space 21A (21) in which the compressor wheel 12A is accommodated. The rotating wheel 12 of the seal structure 2A of the turbocharger is the compressor wheel 12A. As shown in FIG. 1, the first space 21A, which is a space in which the compressor wheel 12A is accommodated, and a seal gap 20A (20) are provided closer to the compressor than the second space 22, in which the bearing 13 is accommodated, in the axial direction of the rotary shaft 11.

[0027] The rotating-side outer peripheral surface 31A (31) may be, for example, an outer peripheral surface of an annular sleeve 15 that is included in the turbocharger 1 as shown in FIG. 1. The sleeve 15 is attached to the rotary shaft 11 between the compressor wheel 12A (rotating wheel 12) and the bearing 13 in the axial direction of the rotary shaft 11 to cover the outer periphery of the rotary shaft 11. The rotating member 3 may further include the sleeve 15. A stationary-side inner peripheral surface 41A (41) may be an inner wall surface of the housing 14 that faces the outer peripheral surface of the sleeve 15 with the seal gap 20B interposed therebetween.

[0028] In some embodiments, as shown in FIG. 1, a seal structure 2B (2) of a turbocharger is for suppressing the leakage of the lubricant from the second space 22 to a first space 21B (21) in which the turbine wheel 12B is accommodated. The rotating wheel 12 of the seal structure 2B of the turbocharger is the turbine wheel 12B. As shown in FIG. 1, the first space 21B, which is a space in which the turbine wheel 12B is accommodated, and the seal gap 20B (20) are provided closer to the turbine than the second space 22, in which the bearing 13 is accommodated, in the axial direction of the rotary shaft 11.

[0029] A rotating-side outer peripheral surface 31B (31) may be, for example, an outer peripheral surface of a boss portion that protrudes from a back surface of the turbine wheel 12B as shown in FIG. 1. A 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 boss portion of the turbine wheel 12B with the seal gap 20B interposed therebetween. In addition, the rotating-side outer peripheral surface 31 may be an outer peripheral surface of the rotary shaft 11.

[0030] In addition, the turbocharger 1 may include both the seal structures 2A and 2B of the turbocharger. That is, each of an end surface of the stationary-side inner peripheral surface 41A that is continuous with the turbine and an end surface of the stationary-side inner peripheral surface 41B that is continuous with the compressor may be the stationary-side end surface 43 including the oil discharge groove 6.

[0031] As shown in FIGS. 3 and 4, an angular position θ is defined such that a position vertically below the axis line LA of the rotary shaft 11 is 0° and the angle increases toward a rotation direction of the rotary shaft 11. In some embodiments, the oil discharge groove 6 includes a pair of groove wall surfaces 62 and 63 that face each other with a gap therebetween in the width direction of the oil discharge groove 6. It is preferable that one groove wall surface 62 of the pair of groove wall surfaces 62 and 63 is provided with an upper end 64 that is continuous with the stationary-side inner peripheral surface 41 in a range in which the angular position θ is equal to or greater than +45° and equal to or less than +95°. It is preferable that the other groove wall surface 63 of the pair of groove wall surfaces 62 and 63 is provided with an upper end 65 that is continuous with the stationary-side inner peripheral surface 41 in a range in which the angular position θ is equal to or greater than -95° and equal to or less than -45°.

[0032] In the embodiment shown in FIG. 3, the upper end 64 of the one groove wall surface 62 is provided at a position where the angular position θ is +45°, and the upper end 65 of the other groove wall surface 63 is provided at a position where the angular position θ is -45°.

[0033] According to the above-described configuration, the upper end 64 of the one groove wall surface 62 is provided in the range in which the angular position θ is equal to or greater than +45° and equal to or less than +95°, and the upper end 65 of the other groove wall surface 63 is provided in the range in which the angular position θ is equal to or greater than -95° and equal to or less than -45°. Therefore, it is possible to reduce an inclination angle with respect to the vertical direction at the connection position of the stationary-side inner peripheral surface 41 with each of the one groove wall surface 62 and the other groove wall surface 63. As a result, it is possible to guide the lubricant flowing down along the stationary-side inner peripheral surface 41 to the oil discharge groove and thus to suppress the accumulation of the lubricant on the stationary-side inner peripheral surface 41. In addition, according to the above-described configuration, since the length of the oil discharge groove 6 in the width direction is large, the flow of the lubricant from the lower portion of the seal gap 20 into the oil discharge groove 6 is promoted.

[0034] In the shown embodiment, the oil discharge groove 6 further has a groove bottom surface 61 that connects the ends of the pair of groove wall surfaces 62 and 63 on the side of the first space 21. The groove bottom surface 61 of the oil discharge groove 6 is formed to include the position where the angular position θ is 0°. The formation of the oil discharge groove 6 to include the position where the angular position θ is 0° makes it possible to directly discharge the lubricant from the lower portion of the seal gap 20, in which the lubricant is accumulated, to the oil discharge groove 6.

[0035] As shown in FIG. 4, it is more preferable that the upper end 64 of the one groove wall surface 62 is provided at a position where the angular position θ is equal to or greater than +85° and equal to or less than +95°. It is more preferable that the upper end 65 of the other groove wall surface 63 is provided at a position where the angular position θ is equal to or greater than -95° and equal to or less than -85°. In the embodiment shown in FIG. 4, the upper end 64 of the one groove wall surface 62 is provided at a position where the angular position θ is +90°, and the upper end 65 of the other groove wall surface 63 is provided at a position where the angular position θ is -90°.

[0036] According to the above-described configuration, the upper end 64 of one groove wall surface 62 is provided in the range in which the angular position θ is equal to or greater than +85° and equal to or less than +95°, and the upper end 65 of the other groove wall surface 63 is provided in the range in which the angular position θ is equal to or greater than -95° and equal to or less than -85°. Therefore, it is possible to reduce the inclination angle with respect to the vertical direction at the connection position of the stationary-side inner peripheral surface 41 with each of the one groove wall surface 62 and the other groove wall surface 63. As a result, it is possible to effectively guide the lubricant flowing down along the stationary-side inner peripheral surface 41 to the oil discharge groove 6 and thus to effectively suppress the accumulation of the lubricant on the stationary-side inner peripheral surface 41.

[0037] In some embodiments, as shown in FIG. 4, when the length of the oil discharge groove 6 in the width direction is L1 and the diameter of the stationary-side inner peripheral surface 41 is L2, the oil discharge groove 6 satisfies a condition of 0.95 × L2 ≤ L1 ≤ 1.05 × L2. In the shown embodiment, the length L1 of the oil discharge groove 6 in the width direction is constant. However, in another embodiment, the oil discharge groove 6 may be configured such that the length of the oil discharge groove 6 in the width direction increases as the oil discharge groove 6 extends downward or may be configured such that the length of the oil discharge groove 6 in the width direction decreases as the oil discharge groove 6 extends downward. In addition, when the length of the oil discharge groove 6 in the width direction is not constant, the length of the upper edge of the oil discharge groove 6 (an edge continuous with the oil-discharge-groove-side edge 42A) in the width direction may be used as the length L1.

[0038] According to the above-described configuration, the length L1 of the oil discharge groove 6 in the width direction is equal to the diameter L2 of the stationary-side inner peripheral surface 41, which makes it possible to effectively guide the lubricant flowing down along the stationary-side inner peripheral surface 41 to the oil discharge groove 6 and to effectively suppress the accumulation of the lubricant on the stationary-side inner peripheral surface 41. In addition, the length L1 of the oil discharge groove 6 in the width direction is equal to the diameter L2 of the stationary-side inner peripheral surface 41, which makes it possible to enhance the discharge performance of the lubricant from the oil discharge groove 6.

[0039] In some embodiments, as shown in FIG. 2, the groove bottom surface 61 is located closer to the first space 21 than the edge 32 on the side of the second space 22 in the rotating-side outer peripheral surface 31 below the axis line LA of the rotary shaft 11.

[0040] According to the above-described configuration, the groove bottom surface 61 is located closer to the first space 21 than the edge 32 on the side of the second space 22 in the rotating-side outer peripheral surface 31 below the axis line LA of the rotary shaft 11. In this case, the seal structure has a shape in which the lubricant flowing down along the rotating-side end surface 33 is less likely to enter the seal gap 20. Therefore, it is possible to suppress the flow of the lubricant into the seal gap 20 and to suppress the accumulation of the lubricant in the lower portion of the seal gap 20.

[0041] FIG. 6 is a schematic cross-sectional view showing a cross section of a seal structure of a turbocharger according to an embodiment along an axis line. FIG. 6 shows a region surrounded by a dashed double-dotted line in FIG. 1. In some embodiments, as shown in FIG. 6, the stationary-side end surface 43 has the oil discharge groove 6 and a flat surface 43B that is provided in a region other than the region in which the oil discharge groove 6 is formed. Similarly to the flat surface 43A, the flat surface 43B extends outward in the radial direction of the rotary shaft 11 from the edge 42 on the side of the second space 22 in the stationary-side inner peripheral surface 41 along the radial direction. The flat surface 43B is located closer to the first space 21 than the edge 32 on the side of the second space 22 in the rotating-side outer peripheral surface 31 below the axis line LA of the rotary shaft 11. In this case, the seal structure has a shape in which the lubricant flowing down along the rotating-side end surface 33 is less likely to enter the seal gap 20. Therefore, it is possible to suppress the flow of the lubricant into the seal gap 20 and to suppress the accumulation of the lubricant in the lower portion of the seal gap 20.

[0042] A protrusion member (not shown) that suppresses the flow of the lubricant from the second space 22 into the seal gap 20 may be provided on the stationary-side inner peripheral surface 41. The protrusion member protrudes from the stationary-side inner peripheral surface 41 to the inside in the radial direction of the rotary shaft 11 and extends along the circumferential direction of the rotary shaft 11.

[0043] In this specification, an expression representing a relative or absolute disposition, such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric", or "coaxial" does not strictly represent only the disposition, but also represents a state of being relatively displaced with a tolerance or a sufficient angle or distance to obtain the same function.

[0044] For example, expressions, such as "identical", "equal", and "homogeneous", representing that things are in an equal state do not strictly represent only the equal state, but also represent a state in which there is a tolerance or a sufficient difference to obtain the same function.

[0045] In addition, in this specification, an expression representing a shape, such as a quadrangular shape or a cylindrical shape, does not represent only a shape, such as a quadrangular shape or a cylindrical shape, in a strictly geometric sense, but also represents a shape including an undulating portion, a chamfered portion, or the like within a range in which the same effect is obtained.

[0046] In addition, in this specification, an expression such as "comprising", "including", or "having" one component is not an exclusive expression excluding the presence of other components.

[0047] The present disclosure is not limited to the above-described embodiments and also includes modifications of the above-described embodiments and appropriate combinations of the modifications.

[0048] The contents described in some embodiments described above are understood as follows, for example.

[0049] 1) A seal structure (2) of a turbocharger (1) according to at least one embodiment of the present disclosure includes: a rotating member (3) that includes at least a rotary shaft (11) of the turbocharger (1) and a rotating wheel (12) provided on one end side of the rotary shaft (11); a stationary member (4) that includes at least a housing (14) accommodating the rotating member (3); a bearing (13) that rotatably supports the rotary shaft (11); and a seal member (5) that is provided in a seal gap (20) which is formed between the rotating member (3) and the stationary member (4) and through which a first space (21), in which the rotating wheel (12) is accommodated, and a second space (22), in which the bearing (13) is accommodated, communicate with each other, in which 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 peripheral surface (41) that defines the seal gap (20) and a stationary-side end surface (43) that extends from an edge (42) on a side of the second space (22) in the stationary-side inner peripheral surface (41) along a radial direction of the rotary shaft (11), and the stationary-side end surface (43) has an oil discharge groove (6) that is provided in the stationary-side end surface (43) below an axis line (LA) of the rotary shaft (11) and extends downward along a vertical direction from the edge (42) on the side of the second space (22) in the stationary-side inner peripheral surface (41).

[0050] According to the configuration of 1), the lubricant can be discharged from the lower portion of the seal gap (20) by the oil discharge groove (6) provided in the stationary-side end surface (43) below the axis line (LA) of the rotary shaft (11). Therefore, it is possible to suppress the accumulation of the lubricant in the lower portion of the seal gap (20). In the seal structure (2) of the turbocharger according to 1), since the accumulation of the lubricant in the lower portion of the seal gap (20) is suppressed, it is possible to suppress the leakage of the lubricant from the seal member (5) provided in the seal gap (20) to the first space (21) (the side on which the rotating wheel 12 is located).

[0051] 2) In some embodiments, in the seal structure (6) of the turbocharger according to 1), the oil discharge groove (6) has a pair of groove wall surfaces (62, 63) that face each other with a gap therebetween in a width direction of the oil discharge groove (6), and when an angular position (θ) is defined such that a position vertically below the axis line (LA) of the rotary shaft (11) is 0° and an angle increases toward a rotation direction of the rotary shaft (11), an upper end (64) of one groove wall surface (62) of the pair of groove wall surfaces (62, 63) is provided in a range in which the angular position (θ) is equal to or greater than +45° and equal to or less than +95°, and an upper end (65) of the other groove wall surface (63) of the pair of groove wall surfaces (62, 63) is provided in a range in which the angular position (θ) is equal to or greater than -95° and equal to or less than -45°.

[0052] According to the configuration of 2), the upper end (64) of the one groove wall surface (62) is provided in the range in which the angular position (θ) is equal to or greater than +45° and equal to or less than +95°, and the upper end (65) of the other groove wall surface (63) is provided in the range in which the angular position (θ) is equal to or greater than -95° and equal to or less than -45°. Therefore, it is possible to reduce the inclination angle with respect to the vertical direction at the connection position of the stationary-side inner peripheral surface (41) with each of the one groove wall surface (62) and the other groove wall surface (63). As a result, it is possible to guide the lubricant flowing down along the stationary-side inner peripheral surface (41) to the oil discharge groove and thus to suppress the accumulation of the lubricant on the stationary-side inner peripheral surface (41).

[0053] 3) In some embodiments, in the seal structure (2) of the turbocharger according to 2), the upper end (64) of the one groove wall surface (62) is provided at a position where the angular position (θ) is equal to or greater than +85° and equal to or less than +95°, and the upper end (65) of the other groove wall surface (63) is provided at a position where the angular position (θ) is equal to or greater than -95° and equal to or less than -85°.

[0054] According to the configuration of 3), the upper end (64) of the one groove wall surface (62) is provided in the range in which the angular position is equal to or greater than +85° and equal to or less than +95°, and the upper end (65) of the other groove wall surface (63) is provided in the range in which the angular position (θ) is equal to or greater than -95° and equal to or less than -85°. Therefore, it is possible to reduce the inclination angle with respect to the vertical direction at the connection position of the stationary-side inner peripheral surface (41). As a result, it is possible to effectively guide the lubricant flowing down along the stationary-side inner peripheral surface (41) to the oil discharge groove (6) and thus to effectively suppress the accumulation of the lubricant on the stationary-side inner peripheral surface (41).

[0055] 4) In some embodiments, in the seal structure (2) of the turbocharger according to 3), when a length of the oil discharge groove (6) in the width direction is L1 and a diameter of the stationary-side inner peripheral surface (41) of the stationary member (4) is L2, the oil discharge groove (6) satisfies a condition of 0.95 × L2 ≤ L1 ≤ 1.05 × L2.

[0056] According to the configuration of 4), the length L1 of the oil discharge groove (6) in the width direction is equal to the diameter L2 of the stationary-side inner peripheral surface (41), which makes it possible to effectively guide the lubricant flowing down along the stationary-side inner peripheral surface (41) to the oil discharge groove (6) and thus to effectively suppress the accumulation of the lubricant on the stationary-side inner peripheral surface (41). In addition, the length L1 of the oil discharge groove (6) in the width direction is equal to the diameter L2 of the stationary-side inner peripheral surface (41), which makes it possible to enhance the discharge performance of the lubricant from the oil discharge groove (6).

[0057] 5) In some embodiments, in the seal structure (2) of the turbocharger according to any one of 2) to 4), the oil discharge groove (6) further has a groove bottom surface (61) that connects edges on a side of the first space (21) in the pair of groove wall surfaces (62, 63), and the groove bottom surface (61) is located closer to the first space (21) than the edge (32) on the side of the second space (22) in the rotating-side outer peripheral surface (31) below the axis line (LA) of the rotary shaft (11).

[0058] According to the configuration of 5), the groove bottom surface (61) is located closer to the first space (21) than the edge (32) on the side of the second space (22) in the rotating-side outer peripheral surface (31) below the axis line (LA) of the rotary shaft (11). In this case, since the seal structure (2) has a shape in which the lubricant flowing down along the rotating-side end surface (33) is less likely to enter the seal gap (20), it is possible to suppress the flow of the lubricant into the seal gap (20) and to suppress the accumulation of the lubricant in the lower portion of the seal gap (20).Reference Signs List

[0059] 1: Turbocharger 2, 2A, 2B: Seal structure 3: Rotating member 4: Stationary member 5: Seal member 6: Oil discharge groove 11: Rotary shaft 12: Rotating wheel 12A: Compressor wheel 12B: Turbine wheel 13: Bearing 14: Housing 15: Sleeve 20, 20A, 20B: Seal gap 21, 21A, 21B: First space 22: Second space 23: Lubricant introduction port 24: Lubricant supply path 25: Lubricant discharge port 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: Oil-discharge-groove-side edge 42B: Flat-surface-side edge 43: Stationary-side end surface 43A, 43B: Flat surface 44: Lower edge 61: Groove bottom surface 62, 63: Groove wall surface 64, 65: Upper end LA: Axis line θ: Angular position

Examples

Embodiment Construction

[0009]Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, dimensions, materials, shapes, relative dispositions, and the like of components described as embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are only explanatory examples.

(Turbocharger)

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

[0011]The bearing 13 is supp...

Claims

1. A seal structure of a turbocharger comprising: a rotating member that includes at least a rotary shaft of the turbocharger and a rotating wheel provided on one end side of the rotary shaft; a stationary member that includes at least a housing accommodating the rotating member; a bearing that rotatably supports the rotary shaft; and a seal member that is provided in a seal gap which is formed between the rotating member and the stationary member and through which a first space, in which the rotating wheel is accommodated, and a second space, in which the bearing is accommodated, communicate with each other, wherein the rotating member includes at least a rotating-side outer peripheral surface that defines the seal gap, the stationary member includes a stationary-side inner peripheral surface that defines the seal gap and a stationary-side end surface that extends from an edge on a side of the second space in the stationary-side inner peripheral surface along a radial direction of the rotary shaft, and the stationary member has an oil discharge groove that is provided in the stationary-side end surface below an axis line of the rotary shaft and extends downward along a vertical direction from the edge on the side of the second space in the stationary-side inner peripheral surface.

2. The seal structure of the turbocharger according to Claim 1, wherein the oil discharge groove has a pair of groove wall surfaces that face each other with a gap therebetween in a width direction of the oil discharge groove, and when an angular position is defined such that a position vertically below the axis line of the rotary shaft is 0° and an angle increases toward a rotation direction of the rotary shaft, an upper end of one groove wall surface of the pair of groove wall surfaces is provided in a range in which the angular position is equal to or greater than +45° and equal to or less than +95°, and an upper end of the other groove wall surface of the pair of groove wall surfaces is provided in a range in which the angular position is equal to or greater than -95° and equal to or less than -45°.

3. The seal structure of the turbocharger according to Claim 2, wherein the upper end of the one groove wall surface is provided at a position where the angular position is equal to or greater than +85° and equal to or less than +95°, and the upper end of the other groove wall surface is provided at a position where the angular position is equal to or greater than -95° and equal to or less than -85°.

4. The seal structure of the turbocharger according to Claim 3, wherein, when a length of the oil discharge groove in the width direction is L1 and a diameter of the stationary-side inner peripheral surface of the stationary member is L2, the oil discharge groove satisfies a condition of 0.95 × L2 ≤ L1 ≤ 1.05 × L2.

5. The seal structure of the turbocharger according to any one of Claims 2 to 4, wherein the oil discharge groove further has a groove bottom surface that connects edges on a side of the first space in the pair of groove wall surfaces, and the groove bottom surface is located closer to the first space than the edge on the side of the second space in the rotating-side outer peripheral surface below the axis line of the rotary shaft.

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