turbocharger

Abstract

This supercharger comprises: a shaft 7; a rolling bearing 60 that includes an inner race 61 attached to the shaft 7 and an outer race 62 disposed around the inner race 61; a housing 2 that includes a bearing hole 22 that accommodates the rolling bearing 60 and a side wall 27 that intersects with the bearing hole; and a bearing holding plate 40, attached to the side wall 27 and facing a side surface 62a of the outer race 62. A lower section of the bearing holding plate 40 includes a small-radius region 45; the distance r1 from the central axis of the shaft 7 to an outer edge 42 of the small-radius region 45 is less than the distance from the central axis to an outer edge of other regions of the bearing holding plate 40; and the distance r1 of the small-radius region is greater than the radius of the bearing hole 22 and equal to or less than the distance r3 from the central axis to an outer edge of a portion of the side wall 27 facing the small-radius region 45.

Description

[Technical Field]

[0001] This application claims the benefit of priority from Japanese Patent Application No. 2023-015246, filed on February 3, 2023, the contents of which are incorporated herein by reference. [Background technology]

[0002] A turbocharger may include a rolling bearing that supports a shaft. For example, the turbocharger of Patent Document 1 includes a pair of rolling bearings. The outer ring of one rolling bearing is positioned by a side wall of the housing, and the outer ring of the other rolling bearing is positioned by a wall separate from the housing. Oil is supplied to the rolling bearings for lubrication. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-81542 Summary of the Invention [Problem to be solved by the invention]

[0004] In a turbocharger, it is desirable to efficiently guide oil in the direction of discharge.

[0005] An object of the present disclosure is to provide a turbocharger that can efficiently guide oil in the discharge direction. [Means for solving the problem]

[0006] In order to solve the above problems, the present disclosure 1stA turbocharger according to an aspect includes: a housing including a shaft, a rolling bearing including an inner ring attached to the shaft and an outer ring disposed around the inner ring, a bearing hole that accommodates the rolling bearing, and a side wall that intersects the bearing hole; and a bearing retainer plate that is attached to the side wall and faces a side surface of the outer ring, wherein a lower part of the bearing retainer plate includes a small radius region, and the distance from the central axis of the shaft to an outer edge in the small radius region is shorter than the distance from the central axis to the outer edge in other regions of the bearing retainer plate, and the above-mentioned distance of the small radius region is greater than the radius of the bearing hole and is equal to or less than the distance from the central axis to the outer edge of a portion of the side wall that faces the small radius region. The outer edge of the small radius region has a horizontal linear shape when viewed in the axial direction of the shaft. .

[0007] In a first aspect, A portion of the outer edge of the bearing retainer plate may be press-fitted into the housing, and the small radius region may be formed in a region of the bearing retainer plate that is not press-fitted into the housing.

[0008] In the first aspect, the bearing retaining plate may further include an oil drainage surface, and the thickness of the bearing retaining plate at the oil drainage surface in the axial direction of the shaft may be smaller than other areas of the bearing retaining plate, and the outer edge of the small radius area may be located within the outer edge of the oil drainage surface. A turbocharger according to a second aspect of the present disclosure includes a housing including a shaft, a rolling bearing including an inner ring attached to the shaft and an outer ring arranged around the inner ring, a bearing hole that houses the rolling bearing, and a side wall that intersects with the bearing hole, and a bearing retainer plate that is attached to the side wall and faces a side surface of the outer ring, wherein a lower part of the bearing retainer plate includes a small radius region, and a first distance from a central axis of the shaft to an outer edge in the small radius region is shorter than a second distance from the central axis to an outer edge in another region of the bearing retainer plate, a bearing retaining plate, wherein a first distance of the region is greater than the radius of the bearing hole and is equal to or less than a third distance from the central axis to the outer edge of the portion of the side wall facing the small radius region, and the housing further includes a groove having an arc shape of greater than 180 degrees when viewed in the axial direction of the shaft, and an oil drain space formed below the groove, and the bearing retaining plate further includes a non-small radius region which is a region other than the small radius region, and a portion of the non-small radius region is press-fitted into the groove, and the remainder of the small radius region and the non-small radius region are exposed to the oil drain space. In the second embodiment, the outer edge of the small radius region may have a horizontal, linear shape when viewed in the axial direction of the shaft. In a second aspect, the bearing retaining plate may further include an oil drainage surface, and the thickness of the bearing retaining plate at the oil drainage surface in the axial direction of the shaft may be smaller than other areas of the bearing retaining plate, and the outer edge of the small radius area may be located within the outer edge of the oil drainage surface. In the first and second embodiments, The small radius region may include a tapered surface whose radius from the central axis decreases from a first end face facing the side surface of the outer ring to a second end face opposite the first end face. [Effects of the Invention]

[0009] According to the present disclosure, oil can be efficiently guided in the discharge direction. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a turbocharger according to an embodiment. [Figure 2] FIG. 2 shows the second side wall of the bearing housing and the bearing retaining plate as viewed in the axial direction. [Figure 3] FIG. 3 is a schematic enlarged cross-sectional view of part A in FIG. [Figure 4]FIG. 4 is a schematic plan view showing the bearing retaining plate. [Figure 5] FIG. 5 is a schematic enlarged cross-sectional view of part B in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Specific dimensions, materials, numerical values, etc. shown in the embodiments are merely examples for ease of understanding and do not limit the present disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present disclosure are not shown.

[0012] 1 is a schematic cross-sectional view showing a turbocharger TC according to an embodiment. For example, the turbocharger TC is applied to an engine. The turbocharger TC includes a housing 1, a shaft 7, a turbine impeller 8, and a compressor impeller 9.

[0013] As will be described later, the shaft 7, the turbine impeller 8, and the compressor impeller 9 rotate integrally with one another. Therefore, in this disclosure, the axial direction, radial direction, and circumferential direction of the shaft 7, the turbine impeller 8, and the compressor impeller 9 may be simply referred to as the "axial direction," the "radial direction," and the "circumferential direction," respectively, unless otherwise specified. Also, in this disclosure, the central axes of the shaft 7, the turbine impeller 8, and the compressor impeller 9 may be simply referred to as the "central axes."

[0014] The housing 1 includes a bearing housing 2, a turbine housing 3, and a compressor housing 4. One axial end of the bearing housing 2 is connected to the turbine housing 3 by a fastening mechanism 21a such as a G coupling. The other axial end of the bearing housing 2 is connected to the compressor housing 4 by a fastening mechanism 21b such as a fastening bolt.

[0015] The bearing housing 2 includes a bearing hole 22. The bearing hole 22 extends in the axial direction within the bearing housing 2. The bearing hole 22 has a cylindrical shape.

[0016] One axial end of the bearing hole 22 is defined by a first side wall 23 of the bearing housing 2. The first side wall 23 is located axially between the turbine impeller 8 and the bearing hole 22. In this embodiment, the first side wall 23 is integral with the bearing housing 2. In other embodiments, the first side wall 23 may be separate from the bearing housing 2 or may be attached to the bearing housing 2.

[0017] The other axial end of the bearing hole 22 is defined by a bearing retaining plate 40. The bearing retaining plate 40 is located axially between the compressor impeller 9 and the bearing hole 22. The bearing retaining plate 40 is a separate body from the bearing housing 2 and is attached to the bearing housing 2.

[0018] More specifically, the bearing housing 2 includes a second side wall 24. A seal plate 30 is disposed adjacent to the second side wall 24. A groove 25 is formed in the second side wall 24. In this embodiment, the bearing retaining plate 40 is press-fitted into the groove 25.

[0019] Figure 2 shows the second side wall 24 and bearing retaining plate 40 of the bearing housing 2 as viewed in the axial direction, with the second side wall 24 and bearing retaining plate 40 viewed from the right side in Figure 1. In Figure 2, the second side wall 24 is hatched for better understanding.

[0020] As described above, the second side wall 24 is formed with the groove 25. For example, the groove 25 has an arc shape of greater than 180 degrees when viewed in the axial direction. The oil discharge space 26 is formed below the groove 25. The groove 25 and the oil discharge space 26 are continuous with each other in the radial direction. Therefore, a portion of the outer edge 42 of the bearing retainer plate 40 is press-fitted into the groove 25, and the remainder of the outer edge 42 is not press-fitted into the groove 25 and is exposed to the oil discharge space 26.

[0021] 3 is a schematic enlarged cross-sectional view of portion A in FIG. 1. Groove 25 includes a third side wall 27. Third side wall 27 corresponds to the bottom surface of groove 25. Third side wall 27 extends radially. Third side wall 27 intersects bearing hole 22. Specifically, third side wall 27 may be perpendicular to bearing hole 22. Bearing retaining plate 40 is disposed adjacent to third side wall 27. For example, bearing retaining plate 40 contacts third side wall 27. The bearing retaining plate 40 will be described in further detail below.

[0022] Referring to FIG. 1 , the bearing hole 22 accommodates a pair of rolling bearings 50, 60. The rolling bearings 50, 60 rotatably support the shaft 7. The pair of rolling bearings 50, 60 are spaced apart from each other in the axial direction. In the present disclosure, the rolling bearing adjacent to the first side wall 23 may be referred to as the first rolling bearing 50. In the present disclosure, the rolling bearing adjacent to the bearing retaining plate 40 may be referred to as the second rolling bearing 60.

[0023] A turbine impeller 8 is provided at a first end (the left end in FIG. 1 ) of the shaft 7 in the axial direction. The turbine impeller 8 is located outside the bearing hole 22 in the axial direction. The turbine impeller 8 is rotatably housed in the turbine housing 3. The turbine impeller 8 rotates integrally with the shaft 7.

[0024] A compressor impeller 9 is provided at a second axial end (the right end in FIG. 1 ) of the shaft 7. The compressor impeller 9 is located axially outside the bearing hole 22. The compressor impeller 9 is rotatably housed in the compressor housing 4. The compressor impeller 9 rotates integrally with the shaft 7.

[0025] The compressor housing 4 includes an intake port 10 at an end axially opposite to the bearing housing 2. The intake port 10 is connected to an air cleaner (not shown). The bearing housing 2 and the compressor housing 4 define a diffuser passage 11 therebetween. The diffuser passage 11 expands in the radial direction. The diffuser passage 11 has a generally annular shape. The diffuser passage 11 communicates with the intake port 10 via the compressor impeller 9.

[0026] The compressor housing 4 includes a compressor scroll passage 12. The compressor scroll passage 12 is located radially outward of the compressor impeller 9. The compressor scroll passage 12 communicates with the diffuser passage 11. The compressor scroll passage 12 also communicates with an intake port of an engine (not shown).

[0027] As the compressor impeller 9 rotates, air is drawn into the compressor housing 4 through the intake port 10. As the drawn air passes through the blades of the compressor impeller 9, it is accelerated and pressurized by centrifugal force. The air is further pressurized in the diffuser passage 11 and the compressor scroll passage 12. The pressurized air flows out from a discharge port (not shown) and is led to the intake port of the engine (not shown).

[0028] The turbine housing 3 includes a discharge port 13 at an end opposite to the bearing housing 2 in the axial direction. The discharge port 13 is connected to an exhaust gas purification device (not shown). The turbine housing 3 includes a flow path 14 and a turbine scroll flow path 15. The turbine scroll flow path 15 is located radially outward from the turbine impeller 8. The flow path 14 is located between the turbine impeller 8 and the turbine scroll flow path 15. The turbine scroll flow path 15 communicates with the flow path 14. The flow path 14 communicates with the discharge port 13 via the turbine impeller 8.

[0029] The turbine scroll passage 15 communicates with a gas inlet (not shown). The gas inlet receives exhaust gas discharged from an exhaust manifold (not shown) of the engine. The exhaust gas is guided from the gas inlet to the turbine scroll passage 15, and then to the discharge port 13 via the passage 14 and the turbine impeller 8. The exhaust gas rotates the turbine impeller 8 as it passes through the blades of the turbine impeller 8.

[0030] 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 from the intake port 10 is compressed as described above. The compressed air is then guided to the intake port of the engine.

[0031] 3, the bearing housing 2 includes a main oil passage 71. The main oil passage 71 extends in the axial direction. The main oil passage 71 extends parallel to the bearing hole 22. The main oil passage 71 is located above the bearing hole 22.

[0032] The bearing hole 22 and the main oil passage 71 open to the third side wall 27. As described above, the bearing retaining plate 40 contacts the third side wall 27. The bearing retaining plate 40 closes the opening of the main oil passage 71.

[0033] The bearing housing 2 includes a through hole 72. The through hole 72 extends from the outer wall of the bearing housing 2 to the main oil passage 71. The through hole 72 communicates with the main oil passage 71. Oil is supplied to the main oil passage 71 from an oil pump (not shown) through the through hole 72.

[0034] The bearing housing 2 includes a first oil passage 73 and a second oil passage 74. The first oil passage 73 and the second oil passage 74 each open to the main oil passage 71. Furthermore, the first oil passage 73 and the second oil passage 74 each open to the bearing hole 22. The first oil passage 73 and the second oil passage 74 each connect the main oil passage 71 and the bearing hole 22. The first oil passage 73 is provided at a position in the axial direction corresponding to the first rolling bearing 50 and opens toward the first rolling bearing 50. The second oil passage 74 is provided at a position in the axial direction corresponding to the second rolling bearing 60 and opens toward the second rolling bearing 60.

[0035] The bearing housing 2 includes a bottom wall 28. The bottom wall 28 defines a lower portion of the bearing hole 22 in the radial direction. The bottom wall 28 includes an oil drain hole 28a. The oil drain hole 28a passes through the bottom wall 28 in the vertical direction. For example, the oil drain hole 28a is located between the first oil passage 73 and the second oil passage 74 in the axial direction. From another perspective, the oil drain hole 28a is located between the first rolling bearing 50 and the second rolling bearing 60 in the axial direction.

[0036] 1, the bearing housing 2 includes an oil outlet 29 below the oil drain hole 28a. The oil outlet 29 guides oil to the outside of the bearing housing 2.

[0037] Referring to FIG. 3, the bearing hole 22 accommodates a portion of the shaft 7. The shaft 7 includes a large diameter portion 7a, a medium diameter portion 7b, and a small diameter portion 7c. In the axial direction, the medium diameter portion 7b is located between the first side wall 23 and the bearing retaining plate 40. In the axial direction, the large diameter portion 7a is located between the first end of the shaft 7 and the medium diameter portion 7b. In the axial direction, the small diameter portion 7c is located between the second end of the shaft 7 and the medium diameter portion 7b. The diameter of the medium diameter portion 7b is smaller than the diameter of the large diameter portion 7a. The diameter of the small diameter portion 7c is smaller than the diameter of the medium diameter portion 7b.

[0038] The shaft 7 includes a first step surface 7d and a second step surface 7e. In the axial direction, the first step surface 7d is located between the large diameter portion 7a and the medium diameter portion 7b. The first step surface 7d extends radially from the outer surface of the large diameter portion 7a to the outer surface of the medium diameter portion 7b. In the axial direction, the second step surface 7e is located between the medium diameter portion 7b and the small diameter portion 7c. The second step surface 7e extends radially from the outer surface of the medium diameter portion 7b to the outer surface of the small diameter portion 7c.

[0039] The first rolling bearing 50 includes an inner ring 51, an outer ring 52, multiple rolling elements 53, and a cage 54. The inner ring 51 is attached to the outer surface of the medium 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 from the inner ring 51. The outer surface of the outer ring 52 faces the inner surface of the bearing hole 22. Multiple rolling elements 53 are disposed between the inner ring 51 and the outer ring 52. The cage 54 holds the multiple rolling elements 53.

[0040] The second rolling bearing 60 includes an inner ring 61, an outer ring 62, multiple rolling elements 63, and a cage 64. The inner ring 61 is attached to the outer surface of the medium 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 from the inner ring 61. The outer surface of the outer ring 62 faces the inner surface of the bearing hole 22. Multiple rolling elements 63 are disposed between the inner ring 61 and the outer ring 62. The cage 64 holds the multiple rolling elements 63.

[0041] In the present disclosure, of the side surfaces 51a, 51b, 61a, 61b of the inner ring 51 of the first rolling bearing 50 and the inner ring 61 of the second rolling bearing 60, the side surfaces 51b, 61b that face each other in the axial direction may be referred to as the "inner surface," and the side surfaces 51a, 61a opposite the inner surfaces 51b, 61b may be referred to as the "outer surface."

[0042] Similarly, in the present disclosure, of the side surfaces 52a, 52b, 62a, 62b of the outer ring 52 of the first rolling bearing 50 and the outer ring 62 of the second rolling bearing 60, the side surfaces 52b, 62b that face each other in the axial direction may be referred to as the "inner surface," and the side surfaces 52a, 62a opposite the inner surface 52b, 62b may be referred to as the "outer surface."

[0043] An outer surface 51a of the inner ring 51 of the first rolling bearing 50 contacts the first stepped surface 7d of the shaft 7 in the axial direction. In addition, an outer surface 52a of the outer ring 52 of the first rolling bearing 50 faces the first side wall 23 of the bearing housing 2 in the axial direction.

[0044] A spacer 80 is disposed in the medium diameter portion 7b of the shaft 7 between the inner ring 51 and the inner ring 61. The spacer 80 has a generally cylindrical shape. The shaft 7 is inserted into the spacer 80. In another embodiment, a spring and a spring retainer may be provided instead of the spacer 80.

[0045] An inner surface 51b of the inner ring 51 of the first rolling bearing 50 contacts one end of the spacer 80 in the axial direction. An inner surface 61b of the inner ring 61 of the second rolling bearing 60 contacts the other end of the spacer 80 in the axial direction.

[0046] An oil thrower member 90 is attached to the small diameter portion 7c of the shaft 7. The oil thrower member 90 scatters oil radially outward. The oil thrower member 90 is disposed radially inward of the bearing retaining plate 40. The oil thrower member 90 and the bearing retaining plate 40 are spaced apart in the radial direction.

[0047] An outer surface 61a of the inner ring 61 of the second rolling bearing 60 contacts the oil thrower member 90 in the axial direction. An outer surface 62a of the outer ring 62 of the second rolling bearing 60 faces the bearing retainer plate 40 in the axial direction.

[0048] Referring to FIG. 1 , during assembly, the first rolling bearing 50, spacer 80, second rolling bearing 60, and oil thrower 90 are mounted onto the shaft 7 in this order, starting from the second end of the shaft 7 (the right end in FIG. 1 ). Next, the bearing retainer plate 40 and the seal plate 30 are assembled to the bearing housing 2. Next, the compressor impeller 9 is mounted onto the shaft 7. Axial compressive stress is applied to the inner ring 51 of the first rolling bearing 50, the spacer 80, the inner ring 61 of the second rolling bearing 60, the oil thrower 90, and the compressor impeller 9 by fastening bolts attached to the second end of the shaft 7, thereby fixing these components to the shaft 7. As a result, the inner ring 51 of the first rolling bearing 50, the spacer 80, the inner ring 61 of the second rolling bearing 60, the oil thrower 90, and the compressor impeller 9 rotate integrally with the shaft 7.

[0049] 3, when a thrust load toward the turbine impeller 8 (thrust load toward the left in FIG. 3) acts on the shaft 7, the outer ring 52 of the first rolling bearing 50 presses the first side wall 23. Therefore, the first side wall 23 restricts the axial movement of the outer ring 52. Furthermore, when a thrust load toward the compressor impeller 9 (thrust load toward the right in FIG. 3) acts on the shaft 7, the outer ring 62 of the second rolling bearing 60 presses the bearing retaining plate 40. Therefore, the bearing retaining plate 40 restricts the axial movement of the outer ring 62. With the above-described configuration, the movement of the shaft 7 due to the thrust load is restricted by the first side wall 23 and the bearing retaining plate 40.

[0050] In this embodiment, the turbocharger TC does not include a rotation stopper for the outer rings 52, 62. When the outer ring 52 is not pressed against the first side wall 23, the outer ring 52 is rotatable in the circumferential direction relative to the bearing housing 2. Similarly, when the outer ring 62 is not pressed against the bearing retaining plate 40, the outer ring 62 is rotatable in the circumferential direction relative to the bearing housing 2. When the shaft 7 rotates, the inner rings 51, 61 rotate integrally with the shaft 7. The rolling elements 53, 63 rotate in conjunction with the rotation of the inner rings 51, 61. The rolling elements 53, 63 move in the circumferential direction. The outer rings 52, 62 rotate in the circumferential direction in conjunction with the rotation and movement of the rolling elements 53, 63 or with the flow of oil. The rotational speed of the outer ring 52 is slower than the rotational speed of the inner ring 51. Furthermore, in this embodiment, the pair of rolling bearings 50, 60 are face-to-face mated. Therefore, no spacer is required between the outer ring 52 and the outer ring 62. Therefore, no preload is applied to the outer rings 52, 62. Therefore, the outer rings 52, 62 are easy to rotate relative to the bearing housing 2.

[0051] Next, the bearing retainer plate 40 will be described in detail.

[0052] FIG. 4 is a schematic plan view showing the bearing retaining plate 40, as viewed axially from the left side in FIG. 1. The bearing retaining plate 40 has a generally annular or disc shape. The bearing retaining plate 40 is disposed concentrically with the shaft 7 (not shown in FIG. 4). The bearing retaining plate 40 includes an inner edge 41 and an outer edge 42. The inner edge 41 has a circular shape when viewed axially. The outer edge 42 has a generally circular shape when viewed axially. The lower portion of the outer edge 42 has a non-circular shape (described in more detail below).

[0053] Fig. 5 is a schematic enlarged cross-sectional view of part B in Fig. 3. For example, the diameter of the inner edge 41 is smaller than the innermost diameter of the outer ring 62 of the second rolling bearing 60 and is larger than the outer diameter of the oil thrower member 90. The diameter of the outer edge 42 is larger than the inner diameter of the bearing hole 22.

[0054] The bearing retaining plate 40 includes a first end face 43 and a second end face 44 in the axial direction. The first end face 43 defines an end of the bearing hole 22 in the axial direction. The first end face 43 contacts the third side wall 27 of the bearing housing 2. Although the first end face 43 contacts the third side wall 27, an oil discharge surface 48 (described later) is spaced axially from the third side wall 27. The first end face 43 directly faces an outer surface 62a of the outer ring 62 of the second rolling bearing 60 in the axial direction. In other words, no other members are disposed between the first end face 43 and the outer surface 62a in the axial direction. The second end face 44 is located opposite the first end face 43 in the axial direction.

[0055] 4, the lower portion of the bearing retaining plate 40 includes a small radius region 45. A distance r1 from the central axis to the outer edge 42 in the small radius region 45 is shorter than a distance r2 from the central axis to the outer edge 42 in other regions of the bearing retaining plate 40. In this embodiment, the outer edge 42 in the small radius region 45 has a horizontal, linear shape when viewed in the axial direction. In other embodiments, the outer edge 42 in the small radius region 45 may have another shape, such as a curved shape, when viewed in the axial direction.

[0056] 5, the distance r1 of the small radius region 45 is greater than the radius of the bearing hole 22. The distance r1 is equal to or less than a distance r3 from the central axis to the outer edge of the portion of the third side wall 27 that faces the small radius region 45 in the axial direction. In this embodiment, the distance r1 is equal to the distance r3. In other embodiments, the distance r1 may be less than the distance r3.

[0057] 2, as described above, groove 25 of housing 2 has an arc shape. Therefore, a portion of outer edge 42 of bearing retaining plate 40 is press-fitted into groove 25, and the remainder of outer edge 42 is not press-fitted into groove 25. Small radius region 45 is formed in an area of ​​bearing retaining plate 40 that is not press-fitted into housing 2. In other words, small radius region 45 is formed in an area of ​​bearing retaining plate 40 that does not overlap with groove 25 in the circumferential direction.

[0058] 5, the small radius region 45 includes a tapered surface 46. Specifically, the tapered surface 46 is formed on the outer peripheral surface of the bearing retaining plate 40. The tapered surface 46 is inclined with respect to the axial direction. The radius of the tapered surface 46 from the central axis decreases from the first end surface 43 toward the second end surface 44. In this embodiment, the tapered surface 46 is a flat surface. In other embodiments, the tapered surface 46 may be a curved surface.

[0059] For example, the small radius region 45 and the tapered surface 46 may be formed by cutting out the lower portion of the annular bearing retaining plate 40. However, the small radius region 45 and the tapered surface 46 are not limited to this and may be formed by other methods. For example, the small radius region 45 and the tapered surface 46 may be formed together with other portions of the bearing retaining plate 40.

[0060] Referring to FIG. 4 , an oil groove 47 and an oil drain surface 48 are formed in the first end face 43. In this embodiment, the oil groove 47 is formed continuously with respect to the inner edge 41. For example, the oil groove 47 is formed with a predetermined width in the radial direction from the inner edge 41. The oil groove 47 extends in the circumferential direction. In this embodiment, the oil groove 47 is continuous in the entire circumferential direction and has an annular shape. The oil groove 47 is formed integrally with the oil drain surface 48 at a lower portion.

[0061] The oil discharge surface 48 is provided in a lower region of the first end face 43. The oil discharge surface 48 has a sector shape concentric with the shaft 7 when viewed in the axial direction.

[0062] Next, the flow of oil around the second rolling bearing 60 will be described.

[0063] 3, oil is supplied from an oil pump (not shown) to a main oil passage 71 via a through hole 72. A portion of the oil is supplied to the first rolling bearing 50 via a first oil passage 73, and the remainder of the oil is supplied to the second rolling bearing 60 via a second oil passage 74.

[0064] 5, the oil supplied to the second rolling bearing 60 is used to lubricate the gap between the inner ring 61 and the rolling elements 63, and between the outer ring 62 and the rolling elements 63. The oil is also used to lubricate the gap between the outer ring 62 and the inner circumferential surface of the bearing hole 22. The oil is guided to the oil groove 47 and the oil drain surface 48 from the gap between the outer ring 62 and the bearing retaining plate 40 and the gap between the outer ring 62 and the inner ring 61.

[0065] A portion of the oil in the oil groove 47 is guided in the circumferential direction by the oil groove 47. The oil is guided from the oil groove 47 to the oil discharge surface 48. The oil discharge surface 48 further guides the oil downward. The oil falls into the oil discharge space 26.

[0066] The remaining oil in the oil groove 47 is guided through the gap between the bearing retaining plate 40 and the oil thrower member 90 to the second end face 44. The second end face 44 further guides the oil downward. The oil falls into the oil drain space 26. The oil in the oil drain space 26 is collected in the oil outlet 29 (not shown in FIG. 5) and discharged to the outside.

[0067] The turbocharger TC as described above includes a shaft 7, a second rolling bearing 60 including an inner ring 61 attached to the shaft 7 and an outer ring 62 disposed around the inner ring 61, a bearing housing 2 including a bearing hole 22 accommodating the second rolling bearing 60 and a third side wall 27 intersecting the bearing hole 22, and a bearing retaining plate 40 attached to the third side wall 27 and directly facing an outer surface 62a of the outer ring 62. A lower portion of the bearing retaining plate 40 includes a small radius region 45. A distance r1 from the central axis to an outer edge 42 in the small radius region 45 is shorter than a distance r2 from the central axis to the outer edge 42 in other regions of the bearing retaining plate 40. Furthermore, the distance r1 of the small radius region 45 is greater than the radius of the bearing hole 22 and is equal to or shorter than a distance r3 from the central axis to the outer edge of the third side wall 27 facing the small radius region 45. With this configuration, the distance r1 of the small radius region 45 is equal to or less than the distance r3 from the central axis to the outer edge of the third side wall 27, and therefore the bearing retaining plate 40 does not protrude downward from the third side wall 27. As a result, a large oil discharge space 26 is ensured, and oil flowing along the second end face 44 can easily pass through the oil discharge space 26. Therefore, the oil can be efficiently guided in the discharge direction.

[0068] Furthermore, with the above-described configuration, the distance r1 of the small radius region 45 is greater than the radius of the bearing hole 22. Therefore, the small radius region 45 can axially block the gap between the bearing hole 22 and the outer ring 62 while ensuring a large oil discharge space 26. If the small radius region 45 were too short and unable to block this gap, oil would splash from this gap in the axial direction. This oil would interfere with the downward flow of oil along the second end face 44. However, with the above-described configuration, oil splashing axially from the gap between the bearing hole 22 and the outer ring 62 is received by the bearing retaining plate 40. Therefore, the downward flow of oil along the second end face 44 is not obstructed. As a result, the oil can be more efficiently guided in the discharge direction.

[0069] Furthermore, with the above-described configuration, the small radius region 45 is positioned vertically downward. Therefore, when assembling the bearing retainer plate 40 to the bearing housing 2, the small radius region 45 can be used as a mark for positioning in the circumferential direction. As a result, no additional mark is required on the bearing retainer plate 40.

[0070] Furthermore, in the turbocharger TC, a part of the outer edge 42 of the bearing retaining plate 40 is press-fitted into the bearing housing 2, and the small radius region 45 is formed in a region of the bearing retaining plate 40 that is not press-fitted into the bearing housing 2. With this configuration, it is possible to form the small radius region 45 while avoiding deformation of the bearing retaining plate 40 due to press-fitting.

[0071] Moreover, in the turbocharger TC, the small radius region 45 includes a tapered surface 46 whose radius from the central axis decreases from a first end face 43 facing the outer surface 62a of the outer ring 62 to a second end face 44 opposite the first end face 43. With this configuration, the oil guided to the second end face 44 flows along the tapered surface 46. The oil flowing along the tapered surface 46 smoothly merges with the oil flowing along the oil discharge surface 48. Therefore, the oil can be more efficiently guided in the discharge direction.

[0072] Although the embodiments have been described above with reference to the accompanying drawings, the present disclosure is not limited to the above-described embodiments. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that such modifications also fall within the technical scope of the present disclosure.

[0073] For example, in the above embodiment, the bearing retaining plate 40 is press-fit into the groove 25 of the bearing housing 2. In other embodiments, for example, the bearing retaining plate 40 may be fixed to the third side wall 27 of the bearing housing 2 by a bolt or the like.

[0074] In the above embodiment, the bearing retaining plate 40 includes a tapered surface 46. However, the tapered surface 46 is not essential.

[0075] In the above embodiment, the bearing retainer plate 40 is applied to the second rolling bearing 60 close to the compressor impeller 9. In other embodiments, the bearing retainer plate 40 may be applied to the first rolling bearing 50 close to the turbine impeller 8.

[0076] In the above embodiment, the supercharger TC includes two rolling bearings 50, 60. In other embodiments, the supercharger TC may include three or more rolling bearings.

[0077] In the above embodiment, the outer rings 52, 62 are rotatable relative to the bearing housing 2. In other embodiments, the outer rings 52, 62 may be rotationally fixed relative to the bearing housing 2.

[0078] In the above embodiment, the pair of rolling bearings 50, 60 are angular bearings. In other embodiments, the rolling bearings may be rolling bearings other than angular bearings (for example, deep groove ball bearings or self-aligning ball bearings). Also, in the above embodiment, the pair of rolling bearings 50, 60 are face-to-face mating. In other embodiments, the pair of rolling bearings 50, 60 may be back-to-back mating.

[0079] This disclosure can reduce oil leakage into the intake air and promote the purification of exhaust gases, thereby contributing to Goal 13 of the United Nations-led Sustainable Development Goals (SDGs), which states, "Take urgent action to combat climate change and its impacts." [Explanation of symbols]

[0080] 2 Bearing housing (housing) 7 shaft 22 Bearing hole 27 Third side wall (side wall) 40 Bearing retainer plate 42 Outer edge of bearing retainer plate 43 First end surface 44 Second end face 45 Small radius area 46 Tapered surface 60 Second rolling bearing 61 Inner circle 62 outer ring 62a Outer surface (side surface) of outer ring r1 Distance from the central axis to the outer edge of the small radius region r2 Distance from the central axis to the outer edge of the bearing retainer plate in other areas r3 Distance from the central axis to the outer edge of the side wall facing the small radius area TC turbocharger

Claims

1. A shaft and a rolling bearing including an inner ring attached to the shaft and an outer ring disposed around the inner ring; a housing including a bearing hole that accommodates the rolling bearing and a side wall that intersects with the bearing hole; a bearing retaining plate attached to the side wall and facing a side surface of the outer ring, a lower portion of the bearing retaining plate including a small radius region; a first distance from a central axis of the shaft to an outer edge of the small radius region is shorter than a second distance from the central axis to an outer edge of the bearing retaining plate in another region; the first distance of the small radius region is greater than a radius of the bearing hole and is equal to or less than a third distance from the central axis to an outer edge of a portion of the side wall facing the small radius region. A bearing retaining plate; Equipped with The outer edge in the small radius region has a horizontal linear shape when viewed in the axial direction of the shaft. Supercharger.

2. A part of the outer edge of the bearing retaining plate is press-fitted into the housing, The turbocharger according to claim 1 , wherein the small radius region is formed in a region of the bearing retaining plate that is not press-fitted into the housing.

3. The bearing retaining plate further includes an oil drain surface, the thickness of the bearing retaining plate at the oil drain surface in the axial direction of the shaft is smaller than that of other areas of the bearing retaining plate, and the outer edge of the small radius area is located within the outer edge of the oil drain surface. The turbocharger according to claim 1 .

4. A shaft, a rolling bearing including an inner ring attached to the shaft and an outer ring disposed around the inner ring; a housing including a bearing hole that accommodates the rolling bearing and a side wall that intersects with the bearing hole; a bearing retaining plate attached to the side wall and facing a side surface of the outer ring, a lower portion of the bearing retaining plate including a small radius region; a first distance from a central axis of the shaft to an outer edge of the small radius region is shorter than a second distance from the central axis to an outer edge of the bearing retaining plate in another region; the first distance of the small radius region is greater than a radius of the bearing hole and is equal to or less than a third distance from the central axis to an outer edge of a portion of the side wall facing the small radius region. A bearing retaining plate; Equipped with The housing includes: a groove having an arc shape of greater than 180 degrees when viewed in the axial direction of the shaft; an oil discharge space formed below the groove; further comprising The bearing retaining plate is a non-small radius region that is a region other than the small radius region; further comprising a portion of the non-small radius region press-fit into the groove; the remainder of the small radius region and the non-small radius region are exposed to the oil scavenge space; Supercharger.

5. The outer edge in the small radius region has a horizontal linear shape when viewed in the axial direction of the shaft. The turbocharger according to claim 4.

6. The bearing retaining plate further includes an oil drain surface, the thickness of the bearing retaining plate at the oil drain surface in the axial direction of the shaft is smaller than that of other areas of the bearing retaining plate, and the outer edge of the small radius area is located within the outer edge of the oil drain surface. The turbocharger according to claim 4.

7. 5. The turbocharger according to claim 1, wherein the small radius region includes a tapered surface whose radius from the central axis decreases from a first end face of the outer ring that faces the side surface toward a second end face that is opposite the first end face.

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