turbocharger

Abstract

The present invention provides a turbocharger (TC) comprising: a shaft (7); a rolling bearing (60) having an inner ring (61) mounted on the shaft (7) and an outer ring (62) disposed around the inner ring (61); a housing (2) including a bearing bore (22) for receiving the rolling bearing (60); a compressor impeller disposed on the shaft (7) outside the bearing bore (22); and an annular bearing plate (40) disposed between the bearing bore (22) and the compressor impeller in the direction of the central axis of the shaft (7), including an end face (41) opposite to the side surface (62a) of the outer ring (62), and the end face (41) including an annular circumferential oil groove (46) extending continuously along the entire circumference of the shaft and a protrusion (48) located in the radial direction of the shaft (7) inside the circumferential oil groove (46) and protruding in the direction of the central axis of the shaft (7).

Description

Technical Field

[0001] This invention relates to a turbocharger. This application claims the benefit of priority based on Japanese Patent Application No. 2021-73665, filed on April 23, 2021, the contents of which are incorporated herein by reference. Background Technology

[0002] The turbocharger may include rolling bearings supporting the rotating shaft. For example, the turbocharger of Patent Document 1 includes a pair of rolling bearings. The outer ring of one of the rolling bearings faces the side wall of the housing. The side wall of the housing has an oil supply groove. The oil supply groove extends radially along the rotating shaft and is inclined relative to a vertical axis extending upward from the rotating shaft.

[0003] Additionally, for example, the turbocharger in Patent Document 2 includes a pair of rolling bearings. The outer ring of one of the rolling bearings faces a damping member. The damping member has a generally annular shape. However, the lower portion of the damping member has a notch and is discontinuous in the circumferential direction. The damping member has an oil supply groove. The oil supply groove includes a generally arc-shaped groove. The arc-shaped groove is separated from the inner periphery of the damping member by a protrusion.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2020 / 021908

[0007] Patent Document 2: Japanese Utility Model Application Publication No. 60-43137 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] In turbochargers, for example, the distance between the bearing bore and the compressor impeller is sometimes shortened for miniaturization. In this case, oil leakage may occur from the housing space between the bearing bore and the compressor impeller.

[0010] The present invention addresses the aforementioned issues with the aim of providing a booster that can reduce oil leakage.

[0011] Solution for solving the problem

[0012] To address the aforementioned issues, one embodiment of the present disclosure provides a turbocharger comprising: a shaft; a rolling bearing having an inner ring mounted on the shaft and an outer ring disposed around the inner ring; a housing including a bearing bore for receiving the rolling bearing; a compressor impeller disposed on the shaft outside the bearing bore; and an annular bearing plate disposed between the bearing bore and the compressor impeller in the direction of the central axis of the shaft, including an end face opposite to the side of the outer ring, and the end face including an annular circumferential oil groove and a protrusion, wherein the circumferential oil groove extends continuously along the entire circumference of the shaft, and the protrusion is located inside the circumferential oil groove in the radial direction of the shaft and protrudes in the direction of the central axis of the shaft.

[0013] The protrusion may also be set within a range of -90 degrees and below 90 degrees relative to a vertical axis extending upward from the central axis of the shaft in the direction of rotation of the shaft.

[0014] Viewed from the direction of the central axis of the shaft, the end face of the bearing pressure plate may also include a guide oil groove extending inward from the outer side of the outer ring and connected to the circumferential oil groove, which may be deeper than the guide oil groove.

[0015] Alternatively, the guide oil trough as a whole may be located in the range of greater than 0 degrees and less than 90 degrees relative to the vertical axis extending upward from the central axis of the rotating shaft in the direction of rotation of the shaft.

[0016] Invention Effects

[0017] According to this disclosure, oil leakage can be reduced. Attached Figure Description

[0018] Figure 1 This is a schematic cross-sectional view of the supercharger in an embodiment.

[0019] Figure 2 yes Figure 1 A simplified enlarged sectional view of part A in the diagram.

[0020] Figure 3 This is a schematic top view showing the bearing pressure plate.

[0021] Figure 4 It is along Figure 3 A rough cross-sectional view obtained from line IV-IV in the diagram.

[0022] Figure 5 This is a schematic top view showing a bearing pressure plate according to another embodiment.

[0023] Figure 6 It is a chart representing the evaluation results of the oil leak.

[0024] Figure 7 This is a schematic top view showing the bearing pressure plate in another embodiment. Detailed Implementation

[0025] In the following detailed description, embodiments of the present disclosure are given with reference to the accompanying drawings. The specific dimensions, materials, and values ​​shown in these embodiments are merely illustrative for ease of understanding and, unless otherwise specified, do not limit the scope of the present disclosure. Furthermore, in this specification and the drawings, elements having substantially the same function or structure are labeled with the same symbols, thereby omitting repeated descriptions. Additionally, elements not directly related to the present invention are omitted from the illustrations.

[0026] Figure 1 This is a schematic cross-sectional view showing an embodiment of the turbocharger TC. For example, the turbocharger TC is used in an engine. The turbocharger TC includes a housing 1, a shaft 7, a turbine impeller 8, and a compressor impeller 9.

[0027] Regarding the direction of the turbocharger TC, unless otherwise indicated in this disclosure, the direction of the central axis, radial direction and circumferential direction of the rotating shaft 7 can be referred to as "central axis direction", "radial direction" and "circumferential direction" respectively.

[0028] Housing 1 includes bearing housing 2, turbine housing 3, and compressor housing 4. Along the central axis, one end of bearing housing 2 is connected to turbine housing 3 via a fastening mechanism 21a such as a G-coupling. Along the central axis, the other end of bearing housing 2 is connected to compressor housing 4 via a fastening mechanism 21b such as fastening bolts.

[0029] The bearing housing 2 includes a bearing bore 22. The bearing bore 22 extends within the bearing housing 2 along a central axis. One end of the bearing bore 22 is defined by a side wall 30 of the bearing housing 2 along the central axis. The side wall 30 is located between the turbine impeller 8 and the bearing bore 22 along the central axis. The other end of the bearing bore 22 is defined by a bearing pressure plate 40 along the central axis. The bearing pressure plate 40 is located between the compressor impeller 9 and the bearing bore 22 along the central axis.

[0030] The sidewall 30 protrudes radially inward relative to the inner circumference of the bearing bore 22. The sidewall 30 is integral with the bearing housing 2. However, in other embodiments, the sidewall 30 may be separate from or mounted on the bearing housing 2. The sidewall 30 includes an end face 31. The end face 31 defines one end of the bearing bore 22 in the direction of the central axis.

[0031] The bearing pressure plate 40 is separate from the bearing housing 2 and is mounted on surface 24 of the bearing housing 2. Surface 24 extends perpendicularly to the inner circumferential surface of the bearing bore 22. For example, the bearing pressure plate 40 is fitted into the bearing housing 2. The bearing pressure plate 40 includes a first end face 41. The first end face 41 defines the other end of the bearing bore 22 in the direction of the central axis. The bearing pressure plate 40 will be described in detail later.

[0032] The bearing bore 22 houses a pair of rolling bearings 50 and 60. The rolling bearings 50 and 60 rotatably support the shaft 7. The pair of rolling bearings 50 and 60 are separated from each other along their central axis. In this disclosure, the rolling bearing adjacent to the sidewall 30 can be referred to as the first bearing 50. In this disclosure, the rolling bearing adjacent to the bearing pressure plate 40 can be referred to as the second bearing 60.

[0033] Along the central axis, a turbine impeller 8 is provided at the first end of the rotating shaft 7. The turbine impeller 8 is located outside the bearing bore 22 along the central axis. The turbine impeller 8 is rotatably housed in the turbine housing 3. Along the central axis, a compressor impeller 9 is provided at the second end of the rotating shaft 7 on the side opposite to the first end. The compressor impeller 9 is located outside the bearing bore 22 along the central axis. The compressor impeller 9 is rotatably housed in the compressor housing 4.

[0034] The compressor housing 4 includes an air inlet 10 at its end opposite to the bearing housing 2 in the direction of its central axis. The air inlet 10 is connected to an air filter (not shown). A diffusion path 11 is fixed between the bearing housing 2 and the compressor housing 4. The diffusion path 11 extends radially from the inside to the outside. The diffusion path 11 has an annular shape. The diffusion path 11 communicates with the air inlet 10 via the compressor impeller 9.

[0035] The compressor housing 4 includes a compressor scroll flow path 12. The compressor scroll flow path 12 is located radially outward relative to the compressor impeller 9. The compressor scroll flow path 12 communicates with a diffuser flow path 11. Additionally, the compressor scroll flow path 12 communicates with an engine intake port (not shown). When the compressor impeller 9 rotates, air is drawn into the compressor housing 4 from the intake port 10. The intake air is accelerated by centrifugal force during its passage through the space between the blades of the compressor impeller 9. The accelerated air is pressurized in the diffuser flow path 11 and the compressor scroll flow path 12. The pressurized air flows out from the discharge port (not shown) and is guided to the engine intake port.

[0036] The turbine housing 3 includes an outlet 13 at its end on the side opposite to the bearing housing 2 in the direction of its central axis. The outlet 13 is connected to an exhaust gas purification device (not shown). The turbine housing 3 includes a flow path 14 and a turbine vortex flow path 15. The turbine vortex flow path 15 is located radially outward relative to the turbine impeller 8. The flow path 14 is located between the turbine impeller 8 and the turbine vortex flow path 15.

[0037] The turbine vortex flow path 15 is connected to a gas inlet (not shown). The gas inlet receives exhaust gas from the exhaust manifold of the engine (not shown). The turbine vortex flow path 15 is connected to a flow path 14. The flow path 14 is connected to an outlet 13 via a turbine impeller 8. Exhaust gas is guided from the gas inlet to the turbine vortex flow path 15, and then through the flow path 14 and the turbine impeller 8 to the outlet 13. During the passage of the exhaust gas through the space between the blades of the turbine impeller 8, the turbine impeller 8 rotates.

[0038] The rotational force of the turbine impeller 8 is transmitted to the compressor impeller 9 via the shaft 7. When the compressor impeller 9 rotates, the air is pressurized as described above. In this way, the pressurized air is guided to the engine intake.

[0039] Figure 2 yes Figure 1 A schematic enlarged sectional view of part A in the diagram. The bearing housing 2 includes a main oil passage 23. The main oil passage 23 extends along the central axis. The main oil passage 23 extends parallel to the bearing bore 22. The main oil passage 23 is located above the bearing bore 22.

[0040] The bearing bore 22 and the main oil passage 23 open on the surface 24 of the bearing housing 2. As described above, a bearing pressure plate 40 is mounted on the surface 24. The bearing pressure plate 40 closes the opening of the main oil passage 23.

[0041] The main oil passage 23 is connected to the through hole 25. The through hole 25 is formed in the bearing housing 2. The through hole 25 extends from the outer wall of the bearing housing 2 to the main oil passage 23. Oil is supplied to the main oil passage 23 via the through hole 25 by an oil pump not shown in the figure.

[0042] The bearing housing 2 includes a first oil passage 26 and a second oil passage 27. The first oil passage 26 and the second oil passage 27 each open into the main oil passage 23. Additionally, the first oil passage 26 and the second oil passage 27 each open into the bearing bore 22. The first oil passage 26 and the second oil passage 27 connect the main oil passage 23 and the bearing bore 22, respectively. The first oil passage 26 is positioned along the central axis corresponding to the first bearing 50 and opens toward the first bearing 50. The second oil passage 27 is positioned along the central axis corresponding to the second bearing 60 and opens toward the second bearing 60.

[0043] The bearing housing 2 includes a lower wall 29. The lower wall 29 defines the lower portion of the bearing bore 22 in the radial direction. The lower wall 29 includes an oil drain hole 29a. The oil drain hole 29a extends vertically through the lower wall 29. For example, in the direction of the central axis, the oil drain hole 29a is located between the first oil passage 26 and the second oil passage 27. That is, the oil drain hole 29a is located between the first bearing 50 and the second bearing 60 in the direction of the central axis.

[0044] The bearing hole 22 accommodates a portion of the rotating shaft 7. The rotating shaft 7 includes a large-diameter portion 7a, a medium-diameter portion 7b, and a small-diameter portion 7c. In the direction of the central axis, the medium-diameter portion 7b is located between the side wall 30 and the bearing pressure plate 40. In the direction of the central axis, the large-diameter portion 7a is located between the first end of the rotating shaft 7 and the medium-diameter portion 7b. In the direction of the central axis, the small-diameter portion 7c is located between the second end of the rotating shaft 7 and the medium-diameter portion 7b. The outer diameter of the medium-diameter portion 7b is smaller than the outer diameter of the large-diameter portion 7a. The outer diameter of the small-diameter portion 7c is smaller than the outer diameter of the medium-diameter portion 7b.

[0045] The rotating shaft 7 includes a first stepped surface 7d and a second stepped surface 7e. In the direction of the central axis, the first stepped surface 7d is located between the large-diameter portion 7a and the intermediate-diameter portion 7b. The first stepped surface 7d extends radially from the outer peripheral surface of the large-diameter portion 7a to the outer peripheral surface of the intermediate-diameter portion 7b. In the direction of the central axis, the second stepped surface 7e is located between the intermediate-diameter portion 7b and the small-diameter portion 7c. The second stepped surface 7e extends radially from the outer peripheral surface of the intermediate-diameter portion 7b to the outer peripheral surface of the small-diameter portion 7c.

[0046] The first bearing 50 includes an inner ring 51, an outer ring 52, a plurality of rolling elements 53, and a retainer 54. The inner ring 51 is mounted on the outer circumferential surface of the mean diameter portion 7b of the shaft 7. The inner ring 51 rotates integrally with the shaft 7. The outer ring 52 is disposed radially outward relative to the inner ring 51. The outer ring 52 faces the inner circumferential surface of the bearing bore 22. A plurality of rolling elements 53 are disposed between the inner ring 51 and the outer ring 52. The retainer 54 holds the plurality of rolling elements 53.

[0047] The second bearing 60 includes an inner ring 61, an outer ring 62, a plurality of rolling elements 63, and a retainer 64. The inner ring 61 is mounted on the outer circumferential surface of the mean diameter portion 7b of the shaft 7. The inner ring 61 rotates integrally with the shaft 7. The outer ring 62 is disposed radially outward relative to the inner ring 61. The outer ring 62 faces the inner circumferential surface of the bearing bore 22. A plurality of rolling elements 63 are disposed between the inner ring 61 and the outer ring 62. The retainer 64 holds the plurality of rolling elements 63.

[0048] In this disclosure, the sides 51a, 51b, 61a, 61b of the inner ring 51 of the first bearing 50 and the inner ring 61 of the second bearing 60 that are opposite each other in the direction of the central axis can be referred to as "inner side surface" 51b, 61b, and the side surface opposite to the inner side surface 51b, 61b can be referred to as "outer side surface" 51a, 61a.

[0049] Similarly, in this disclosure, the sides 52a, 52b, 62a, 62b of the outer ring 52 of the first bearing 50 and the outer ring 62 of the second bearing 60 that are opposite each other in the direction of the central axis can be referred to as "inner sides" 52b and 62b, and the sides opposite to the inner sides 52b and 62b can be referred to as "outer sides" 52a and 62a.

[0050] The outer surface 51a of the inner ring 51 of the first bearing 50 contacts the first stepped surface 7d of the rotating shaft 7 in the direction of the central axis. In addition, the outer surface 52a of the outer ring 52 of the first bearing 50 is opposite to the end face 31 of the sidewall 30 in the direction of the central axis.

[0051] In the middle diameter portion 7b of the rotating shaft 7, a spacer 70 is provided between the inner ring 51 and the inner ring 61. The spacer 70 has a generally cylindrical shape. The rotating shaft 7 is inserted into the spacer 70. In other embodiments, a spring and a spring bracket may be provided instead of the spacer 70.

[0052] The inner surface 51b of the inner ring 51 of the first bearing 50 contacts one end of the spacer 70 in the direction of the central axis. The inner surface 61b of the inner ring 61 of the second bearing 60 contacts the other end of the spacer 70 in the direction of the central axis.

[0053] An oil-slinging component 80 is installed in the small diameter portion 7c of the rotating shaft 7. The oil-slinging component 80 causes oil to spray outward in a radial direction. The oil-slinging component 80 is located on the radially inner side of the bearing pressure plate 40. The oil-slinging component 80 and the bearing pressure plate 40 are radially separated.

[0054] The outer surface 61a of the inner ring 61 of the second bearing 60 contacts the oil-slinging component 80 in the direction of the central axis. In addition, the outer surface 62a of the outer ring 62 of the second bearing 60 is opposite to the bearing pressure plate 40 in the direction of the central axis.

[0055] The first bearing 50, spacer 70, second bearing 60, oil slinger 80, and compressor impeller 9 are installed on the compressor impeller 9 side of the rotating shaft 7 in this order. Compressive stress is applied to these components in the direction of the central axis by fastening bolts installed at the second end of the rotating shaft 7, thereby applying axial force to the rotating shaft 7. The inner ring 51 of the first bearing 50, the spacer 70, the inner ring 61 of the second bearing 60, the oil slinger 80, and the compressor impeller 9 rotate integrally with the rotating shaft 7.

[0056] The outer peripheral surface 52c of the outer ring 52 of the first bearing 50 includes a notch 55. The notch 55 has an annular shape. The notch 55 is adjacent to the outer surface 52a. The outer diameter of the outer surface 52a is smaller than the diameter of the outer peripheral surface 52c by the radial length of the notch 55.

[0057] The outer peripheral surface 62c of the outer ring 62 of the second bearing 60 includes a notch 65. The notch 65 has an annular shape. The notch 65 is adjacent to the outer surface 62a. The outer diameter of the outer surface 62a is smaller than the diameter of the outer peripheral surface 62c by the radial length of the notch 65.

[0058] When a thrust load is applied to the shaft 7 toward the turbine impeller 8, the outer ring 52 of the first bearing 50 presses against the sidewall 30. Therefore, the sidewall 30 functions as a limiting member restricting the axial movement of the outer ring 52. Furthermore, when a thrust load is applied to the shaft 7 toward the compressor impeller 9, the outer ring 62 of the second bearing 60 presses against the bearing pressure plate 40. Therefore, the bearing pressure plate 40 functions as a limiting member restricting the axial movement of the outer ring 62. With this structure, the movement of the shaft 7 caused by the thrust load is prevented by the sidewall 30 and the bearing pressure plate 40.

[0059] In this embodiment, the turbocharger TC does not have anti-rotation elements for the outer rings 52 and 62. The outer ring 52 can rotate circumferentially relative to the bearing housing 2 when not pressing against the sidewall 30. Similarly, the outer ring 62 can rotate circumferentially relative to the bearing housing 2 when not pressing against the bearing pressure plate 40. When the shaft 7 rotates, the inner rings 51 and 61 rotate integrally with the shaft 7. The rolling elements 53 and 63 rotate along with the rotation of the inner rings 51 and 61. The rolling elements 53 and 63 move circumferentially. The outer rings 52 and 62 rotate circumferentially with the rotation and movement of the rolling elements 53 and 63, or with the flow of oil. The rotational speed of the outer ring 52 is slower than that of the inner ring 51. Furthermore, in this embodiment, the pair of rolling bearings 50 and 60 are front-mounted. Therefore, no spacer is needed between the outer rings 52 and 62. Therefore, no preload is applied to the outer rings 52 and 62. Therefore, the outer rings 52 and 62 can easily rotate relative to the bearing housing 2.

[0060] Next, the bearing pressure plate 40 will be described in detail.

[0061] Figure 3 This is a schematic top view of the bearing pressure plate 40, viewed from the bearing hole 22 along the central axis. That is, Figure 3 It is along Figure 2 It is obtained from line III-III in the middle. Figure 3 In the diagram, the inner diameter of the bearing bore 22 is indicated by a dashed line. Additionally, the outer diameter of the outer surface 62a of the second bearing 60 is indicated by a dashed line. The symbol Z represents a vertical shaft extending upwards from the central axis of the rotating shaft 7.

[0062] The bearing pressure plate 40 has a generally annular or disc shape. The bearing pressure plate 40 includes an inner peripheral edge 43 and an outer peripheral edge 44.

[0063] Reference Figure 2For example, the diameter of the inner circumference 43 is smaller than the innermost diameter of the outer ring 62 of the second bearing 60 and larger than the outer diameter of the oil-slinging component 80. Additionally, for example, the diameter of the outer circumference 44 is larger than the inner diameter of the bearing bore 22. The bearing pressure plate 40 includes a first end face 41 and a second end face 42 in the central axial direction. As described above, the first end face 41 defines the end of the bearing bore 22 in the central axial direction. The first end face 41 is opposite to the outer surface 62a of the outer ring 62 in the central axial direction. The second end face 42 is located on the opposite side of the first end face 41.

[0064] Reference Figure 3 The first end face 41 includes a guide oil groove 45, a circumferential oil groove 46, an oil discharge surface 47, and a protrusion 48.

[0065] The guide oil groove 45 connects the gap between the outer ring 62 and the bearing hole 22 and the circumferential oil groove 46, guiding the oil in the gap to the circumferential oil groove 46. Viewed from the central axis direction, the guide oil groove 45 extends radially inward from the outer side surface 62a of the outer ring 62. In this embodiment, the guide oil groove 45 has a generally straight shape along the radial direction. In this embodiment, the guide oil groove 45 has a central axis 45a extending radially. In this embodiment, the central axis 45a is located on the vertical axis Z. In other embodiments, the guide oil groove 45 may extend inward from the outer side surface 62a, or it may not be radial. That is, in other embodiments, the central axis 45a may not extend toward the central axis of the rotating shaft 7. The guide oil groove 45 extends to and connects with the circumferential oil groove 46.

[0066] In a cross-section perpendicular to the radial direction, the guide oil groove 45 can have various cross-sectional shapes, such as a semi-circular shape, a triangular shape, or a quadrilateral shape. The dimensions of the guide oil groove 45, such as its width and depth, are determined, for example, based on factors such as the flow rate of oil supplied to the second bearing 60.

[0067] The circumferential oil groove 46 receives oil from the guide oil groove 45 and guides the received oil in a circumferential direction. The circumferential oil groove 46 is located radially inside the guide oil groove 45. The circumferential oil groove 46 is connected to the guide oil groove 45. The circumferential oil groove 46 extends in a circumferential direction. The circumferential oil groove 46 is continuous throughout the entire circumferential direction and has an annular shape. The circumferential oil groove 46 is separated from the inner peripheral edge 43 by a protrusion 48. The circumferential oil groove 46 is integrally formed with the oil discharge surface 47 at its lower part.

[0068] Reference Figure 2 In this embodiment, the outer diameter of the circumferential oil groove 46 is the same as or approximately the same as the inner diameter of the outer surface 62a of the outer ring 62. In other embodiments, the outer diameter of the circumferential oil groove 46 may be smaller or larger than the inner diameter of the outer surface 62a.

[0069] Figure 4 It is along Figure 3 A schematic cross-sectional view obtained along line IV-IV. In this embodiment, the depth d1 of the circumferential oil groove 46 is deeper than the depth d2 of the guide oil groove 45. In other embodiments, the depth d1 of the circumferential oil groove 46 may also be the same as the depth d2 of the guide oil groove 45.

[0070] In a cross-section perpendicular to the circumferential direction, the circumferential oil groove 46 can have various cross-sectional shapes, such as a semi-circular shape, a triangular shape, or a quadrilateral shape. The dimensions of the circumferential oil groove 46, such as its width and depth, are determined, for example, based on factors such as the flow rate of oil supplied to the second bearing 60.

[0071] An oil drain surface 47 is located in the lower region of the first end face 41. The oil drain surface 47 guides oil that is below the rotating shaft 7 toward the lower wall 29. The oil drain surface 47 is continuously formed in the circumferential oil groove 46. Therefore, the depth of the oil drain surface 47 is the same as the depth d2 of the circumferential oil groove 46.

[0072] Reference Figure 3 Viewed from the central axis, the oil drain surface 47 has a fan-shaped shape coaxial with the rotating shaft 7. For example, the oil drain surface 47 can be provided only within a range of 90 degrees or more and 270 degrees or less in the rotational direction relative to the vertical axis Z. That is, the oil drain surface 47 can be provided only in the lower half of the bearing pressure plate 40.

[0073] The protrusion 48 is located radially inside the circumferential oil groove 46. In this embodiment, the protrusion 48 extends continuously along the entire circumferential direction. That is, in this embodiment, the protrusion 48 has an annular shape.

[0074] Reference Figure 4 The protrusion 48 extends from the circumferential oil groove 46 toward the second bearing 60 along the central axis. Regarding the height of the protrusion 48, for example, the protrusion 48 may also be flush with the first end face 41.

[0075] Reference Figure 2 In the aforementioned turbocharger TC, when oil is supplied to the main oil passage 23 through the through hole 25, the oil flows from the second oil passage 27 to the gap between the outer peripheral surface 62c of the outer ring 62 of the second bearing 60 and the bearing bore 22. From this gap, the oil is supplied to the space around the shaft 7 via the outer surface 62a and the inner surface 62b. With this structure, oil is supplied to the space between the inner ring 61 and the outer ring 62.

[0076] Reference Figure 3Especially when the outer surface 62a of the outer ring 62 contacts the first end face 41 of the bearing plate 40, oil is supplied to the circumferential oil groove 46 through the guide oil groove 45 of the bearing plate 40. The oil in the circumferential oil groove 46 is guided in the circumferential direction along the protrusion 48. With this structure, the length of the gap between the bearing plate 40 and the oil-throwing member 80 in the central axis direction is increased by the amount of the height of the protrusion 48, thus reducing oil leakage to the second section 42 of the bearing plate 40. For example, when the distance between the bearing bore 22 and the compressor impeller 9 is shortened for miniaturization, there may be a problem of oil leakage from the bearing bore 22 to the receiving space of the compressor impeller 9. With the structure described above, such oil leakage can be reduced. In addition, the oil is guided along the protrusion 48 in the central axis direction toward the space between the inner ring 61 and the outer ring 62. Therefore, the oil can be efficiently guided to the space between the inner ring 61 and the outer ring 62. Therefore, the lubrication of the second bearing 60 can be improved.

[0077] Reference Figure 2 When oil is supplied to the main oil passage 23 through the through hole 25, the oil flows from the first oil passage 26 to the gap between the outer peripheral surface 52c of the outer ring 52 of the first bearing 50 and the bearing hole 22. From this gap, the oil flows through the outer side surface 52a and the inner side surface 52b to the space around the rotating shaft 7. With this structure, oil is supplied to the space between the inner ring 51 and the outer ring 52, and to the space between the side wall 30 and the large diameter portion 7a of the rotating shaft 7.

[0078] The above-described turbocharger TC includes: a rotating shaft 7; a second bearing 60 having an inner ring 61 mounted on the rotating shaft 7 and an outer ring 62 disposed around the inner ring 61; a bearing housing 2 including a bearing bore 22 for receiving the second bearing 60; a compressor impeller 9 disposed on the rotating shaft 7 outside the bearing bore 22; and an annular bearing pressure plate 40 disposed between the bearing bore 22 and the compressor impeller 9 in the central axial direction, including a first end face 41 opposite to the outer surface 62a of the outer ring 62, and the first end face 41 including an annular circumferential oil groove 46 extending continuously along the entire circumferential direction and a protrusion 48 located radially inside the circumferential oil groove 46 and protruding in the central axial direction. With this structure, as described above, the length of the gap between the bearing pressure plate 40 and the oil slinger 80 in the central axial direction is increased by the amount of the height of the protrusion 48, thus reducing oil leakage to the second end face 42 of the bearing pressure plate 40. Therefore, oil leakage can be reduced. Furthermore, according to this structure, oil is guided along the protrusion 48 towards the space between the inner ring 61 and the outer ring 62 in the direction of the central axis. Therefore, oil can be efficiently guided to the space between the inner ring 61 and the outer ring 62. Thus, the lubrication of the second bearing 60 can be improved.

[0079] Furthermore, in the turbocharger TC, viewed from the central axis direction, the first end face 41 of the bearing pressure plate 40 includes a guide oil groove 45 extending inward from the outer side 62a of the outer ring 62 and connected to a circumferential oil groove 46, which is deeper than the guide oil groove 45. In this case, more oil is guided downward along the circumferential direction, thus enabling efficient oil guidance in the discharge direction.

[0080] Next, other embodiments of the bearing pressure plate will be described.

[0081] Figure 5 This is a schematic top view showing a bearing pressure plate 90 according to another embodiment. Figure 5 In the diagram, arrow R indicates the direction of rotation of shaft 7. Symbol Z represents a vertical axis extending upward from the central axis of shaft 7. Bearing pressure plate 90 differs from bearing pressure plate 40 described above in that the guide oil groove 45 is inclined in the direction of rotation R of shaft 7. In other respects, bearing pressure plate 90 may be the same as bearing pressure plate 40.

[0082] In this embodiment, the guide oil groove 45 includes the outermost and innermost radial portions, and its overall position relative to the vertical axis Z in the rotational direction R is within a range of greater than 0 degrees and less than 90 degrees Ar. Figure 5 In the diagram, the shaded area represents the range Ar. In this embodiment, the central axis 45a is located at 45 degrees relative to the vertical axis Z in the rotation direction R. That is, the angle α between the central axis 45a and the vertical axis Z is 45 degrees. In other embodiments, as long as the guide oil groove 45 is entirely located within the range Ar1, the angle α can be greater than 0 degrees and less than 90 degrees.

[0083] The turbocharger TC equipped with the aforementioned bearing pressure plate 90 can achieve roughly the same effect as the turbocharger TC equipped with the bearing pressure plate 40.

[0084] In particular, in the bearing pressure plate 90, the guide oil groove 45 is located within a range of greater than 0 degrees and less than 90 degrees relative to the vertical axis Z in the rotational direction R. According to this structure, oil through the guide oil groove 45 is supplied to the space around the rotating shaft 7 within a range Ar of greater than 0 degrees and less than 90 degrees relative to the vertical axis Z in the rotational direction R. In this case, both gravity and the rotational force from the rotating shaft 7 act downwards on the oil. Therefore, the oil flows rapidly downwards towards the lower wall 29, including the drain hole 29a. Thus, the oil can be efficiently guided in the discharge direction. Furthermore, around the gap between the bearing pressure plate 90 and the oil-throwing member 80, the oil is efficiently guided in the discharge direction, thereby reducing oil leakage from the bearing hole 22 into the gap.

[0085] Next, the evaluation of the oil leak will be explained.

[0086] Figure 6 This is a chart representing the evaluation results of the oil leak. In Figure 6 In the evaluation, the following four types of bearing plates were used in the turbocharger TC.

[0087] Comparative example: The guide oil groove 45 is located at 0 degrees relative to the vertical axis Z in the rotation direction R.

[0088] That is, the guide oil groove 45 is located on the vertical axis Z.

[0089] No protrusions were provided.

[0090] In other aspects, it is the same as bearing pressure plate 40.

[0091] Example 1: The guide oil groove 45 is located at 0 degrees relative to the vertical axis Z in the rotation direction R.

[0092] That is, the guide oil groove 45 is located on the vertical axis Z.

[0093] It has protrusions.

[0094] Example 2: The guide oil groove 45 is located at 60 degrees relative to the vertical axis Z in the rotation direction R.

[0095] It has protrusions.

[0096] Example 3: The guide oil groove 45 is located at 45 degrees relative to the vertical axis Z in the rotation direction R.

[0097] It has protrusions.

[0098] The following evaluation was performed using each of the four types of bearing plates.

[0099] The shaft 7 is rotated at multiple speeds. At each of the multiple speeds, oil is supplied from the oil pump to the booster TC at multiple flow rates. The flow rate at which oil leakage occurs from the gap between the bearing plate and the oil slinger is measured and confirmed. For the flow rate at which leakage occurs at each speed, the ratio of the flow rate of each of the four bearing plates to the flow rate of the comparative example is calculated. The calculated value is expressed as the "improvement rate" on the vertical axis of Figure 8. When the improvement rate is greater than 1, the oil leakage is reduced compared to the comparative example. Conversely, when the improvement rate is less than 1, the oil leakage is increased compared to the comparative example. The solid line represents the improvement rate of the comparative example relative to the comparative example, and therefore always represents 1. The double-dotted line represents the improvement rate of Example 1 relative to the comparative example. The dashed line represents the improvement rate of Example 2 relative to the comparative example. The single-dotted line represents the improvement rate of Example 3 relative to the comparative example.

[0100] Lubrication issues may arise in the high-speed range, which could also lead to oil leakage. Therefore, the focus is on improving performance in the high-speed range.

[0101] By comparing the comparative example and Example 1, it can be determined whether the protrusion helps reduce oil leakage. As clearly shown in Figure 8, the improvement rate of Example 1 is greater than 1. Therefore, it can be concluded that the protrusion helps reduce oil leakage.

[0102] By comparing Examples 1, 2, and 3, it can be seen whether tilting the guide oil tank 45 in the rotational direction helps reduce oil leakage. As clearly shown in Figure 8, the improvement rate of Example 2 is higher than that of Example 1. Furthermore, the improvement rate of Example 3 is higher than that of Example 1. Therefore, it can be seen that tilting the guide oil tank 45 in the rotational direction helps reduce oil leakage. Additionally, the improvement rate of Example 3 is approximately the same as that of Example 2. Therefore, it can be seen that even when the guide oil tank 45 is tilted greater than 45 degrees, the improvement rate is approximately the same as when the guide oil tank 45 is tilted at 45 degrees. Therefore, it can be seen that tilting the guide oil tank 45 at 45 degrees can sufficiently reduce oil leakage.

[0103] The embodiments have been described above with reference to the accompanying drawings, but this disclosure is not limited to the above embodiments. Those skilled in the art will be able to conceive of various modifications or alterations within the scope of the claims, and these naturally fall within the technical scope of this invention.

[0104] For example, in the above embodiment, the protrusion 48 extends continuously along the entire circumference. However, in other embodiments, the protrusion 48 may only be provided on a portion of the circumference. For example, Figure 7 This is a schematic top view showing a bearing pressure plate 91 according to another embodiment. The bearing pressure plate 91 differs from the bearing pressure plate 40 described above in that the protrusion 48 is provided only within a range of -90 degrees to 90 degrees relative to the vertical axis Z in the rotational direction R. In other aspects, the bearing pressure plate 91 can also be the same as the bearing pressure plate 40. That is, in the bearing pressure plate 91, the protrusion 48 is provided only in the upper half of the bearing pressure plate 91. In this case, the weight of the bearing pressure plate 91 can be reduced.

[0105] Additionally, for example, in the above embodiment, the turbocharger TC has two rolling bearings 50 and 60 separated in the bearing bore 22 along the central axis direction. However, in other embodiments, the turbocharger TC may also have three or more rolling bearings.

[0106] In the above-described embodiments, the outer rings 52 and 62 are rotatable relative to the bearing housing 2. However, in other embodiments, the outer rings 52 and 62 may also be fixed relative to the bearing housing 2 in the rotational direction.

[0107] In the above embodiment, the pair of rolling bearings 50 and 60 are angular contact bearings and are a front-side combination. However, in other embodiments, the rolling bearings may also be rolling bearings other than angular contact bearings (e.g., deep groove ball bearings or self-aligning ball bearings). Additionally, the pair of rolling bearings 50 and 60 may also be a back-side combination.

[0108] This disclosure can reduce oil leakage into the intake air and promote cleaner exhaust gases, thus contributing to Goal 13 of the United Nations-led Sustainable Development Goals (SDGs): “Take emergency action to address climate change and its impacts.”

[0109] Symbol Explanation

[0110] 2—Bearing housing, 7—Shaft, 8—Turbine impeller, 9—Compressor impeller, 22—Bearing bore, 40—Bearing pressure plate, 41—First end face, 45—Guide oil groove, 46—Circumferential oil groove, 48—Protrusion, 50—First bearing (rolling bearing), 51—Inner ring, 52—Outer ring, 52a—Outer side (side), 90—Bearing pressure plate, 91—Bearing pressure plate, R—Rotation direction, TC—Intensifier, Z—Vertical shaft.

Claims

1. A booster, characterized in that, have: Shaft; A rolling bearing having an inner ring mounted on the shaft and an outer ring disposed around the inner ring; A housing, comprising a bearing bore for receiving the rolling bearing; A compressor impeller, disposed on the outside of the bearing bore of the shaft; and A circular bearing pressure plate is disposed between the bearing bore and the compressor impeller along the central axis of the rotating shaft. It includes an end face opposite the side of the outer ring, and the end face includes a circular circumferential oil groove and a protrusion. The circumferential oil groove extends continuously along the entire circumference of the rotating shaft, and the protrusion is located radially inside the circumferential oil groove and protrudes along the central axis of the rotating shaft. Viewed from the central axis of the rotating shaft, the end face of the bearing pressure plate includes a guide oil groove extending inward from the outer side of the outer ring and connected to the circumferential oil groove. The circumferential oil groove is deeper than the guide oil groove.

2. The booster according to claim 1, characterized in that, The protrusion is positioned only within a range of -90 degrees and below 90 degrees relative to a vertical axis extending upward from the central axis of the rotating shaft in the direction of rotation of the rotating shaft.

3. The booster according to claim 1, characterized in that, The guide oil groove as a whole is located in the range of greater than 0 degrees and less than 90 degrees relative to the vertical axis extending upward from the central axis of the rotating shaft in the direction of rotation of the rotating shaft.

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