Bearings and superchargers

Abstract

The present invention provides a bearing (13), comprising: an annular body (13a) through which a shaft (15) is inserted; a plurality of oil supply grooves (39) arranged on the inner peripheral surface of the body (13a) and extending along the axial direction of the body (13a); a thrust bearing surface (13i) arranged on the end face of the body (13a); a plurality of tapered portions (41) separated from the outer peripheral edge of the thrust bearing surface (13i) and arranged on the thrust bearing surface (13i) at intervals in the circumferential direction of the body (13a), and connected to the oil supply groove (39) and becoming shallower as it moves forward along the circumference; and an oil drain groove (45) arranged on the thrust bearing surface (13i), passing through one tapered portion (41-2) among the plurality of tapered portions (41), and connecting the oil supply groove (39) to the outer peripheral edge.

Description

Technical Field

[0001] The present invention relates to a bearing and a supercharger. This application claims the benefit of priority based on Japanese Patent Application No. 2020-191119, filed on November 17, 2020, the contents of which are incorporated herein by reference. Background Art

[0002] Bearings for supporting shafts are used in various devices. For example, Patent Document 1 discloses a supercharger equipped with bearings for supporting shafts. Lubricating oil is supplied to bearings used in superchargers and the like.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 5807436 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] Some bearings that support shafts include a thrust bearing surface that supports components adjacent to the bearing in the axial direction in the thrust direction (i.e., a thrust bearing). Lubricating oil supplied to the interior of the bearing is supplied to the thrust bearing surface of the bearing as the shaft rotates. The thrust load (i.e., load in the thrust direction) is supported by the oil film pressure of the lubricating oil supplied to the thrust bearing surface. In such bearings, it is desirable to increase the load resistance in the thrust direction (in other words, the load capacity).

[0008] An object of the present disclosure is to provide a bearing and a supercharger capable of improving the load resistance of the bearing in the thrust direction.

[0009] Means for solving problems

[0010] In order to solve the above-mentioned problems, the bearing disclosed in the present invention comprises: an annular body, through which a shaft is inserted; a plurality of oil supply grooves, which are arranged on the inner peripheral surface of the body and extend in the axial direction of the body; a thrust bearing surface, which is arranged on the end face of the body; a plurality of tapered portions, which are separated from the outer peripheral edge of the thrust bearing surface and are arranged on the thrust bearing surface at intervals in the circumferential direction of the body, and are connected to the oil supply grooves, becoming shallower as they move forward along the circumference; and an oil drain groove, which is arranged on the thrust bearing surface, passes through one of the plurality of tapered portions, and connects the oil supply groove to the outer peripheral edge.

[0011] The ratio of the flow path cross-sectional area of ​​the opening on the outer peripheral edge side of the oil drain groove to the area of ​​the thrust bearing surface may be 0.01 or less.

[0012] The ratio of the flow path cross-sectional area of ​​the opening on the outer peripheral edge side of the oil drain groove to the area of ​​the thrust bearing surface may be 0.003 or more.

[0013] In order to solve the above-mentioned problems, the supercharger of the present disclosure includes the above-mentioned bearing.

[0014] Effects of the Invention

[0015] According to the present disclosure, the load resistance of the bearing in the thrust direction can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic cross-sectional view of a supercharger according to an embodiment of the present disclosure.

[0017] Figure 2 yes Figure 1 Extracted image of the dotted line part.

[0018] Figure 3 This is a front view showing a thrust bearing surface in a bearing according to an embodiment of the present disclosure.

[0019] Figure 4 Yes Figure 3 Cross-sectional view of section AA.

[0020] Figure 5 It is from Figure 3 Observe the bearing in the direction of arrow B in the figure.

[0021] Figure 6 This is a graph showing the relationship between the ratio of the flow path cross-sectional area of ​​the opening on the outer peripheral side of the oil drain groove to the area of ​​the thrust bearing surface and the flow rate of lubricating oil discharged from the bearing according to an embodiment of the present disclosure.

[0022] Figure 7 This is a graph showing the relationship between the ratio of the flow path cross-sectional area of ​​the opening on the outer peripheral side of the oil drain groove to the area of ​​the thrust bearing surface and the temperature of the oil film formed on the thrust bearing surface in the bearing according to the embodiment of the present disclosure. DETAILED DESCRIPTION

[0023] The following describes embodiments of the present disclosure with reference to the accompanying drawings. Dimensions, materials, and other specific numerical values ​​shown in the embodiments are merely illustrative for ease of understanding and, unless otherwise stated, do not limit the present disclosure. Furthermore, in this specification and the accompanying drawings, elements having substantially the same function or structure are denoted by the same reference numerals, and repeated description is omitted. Furthermore, elements not directly related to the present disclosure are omitted from illustration.

[0024] Figure 1 This is a schematic cross-sectional view of the supercharger TC. Figure 1 In the figure, the arrow U is the vertical upward direction, and the arrow D is the vertical downward direction. Figure 1The direction of arrow L shown is explained as the left side of the supercharger TC. Figure 1 The direction of arrow R shown is explained as the right side of the supercharger TC. Figure 1 As shown, the supercharger TC includes a supercharger body 1. The supercharger body 1 includes a bearing housing 3, a turbine housing 5, and a compressor housing 7. The turbine housing 5 is connected to the left side of the bearing housing 3 by a fastening mechanism 9. The compressor housing 7 is connected to the right side of the bearing housing 3 by a fastening bolt 11.

[0025] A protrusion 3a is provided on the outer circumferential surface of the bearing housing 3. The protrusion 3a is located on the turbine housing 5 side. The protrusion 3a protrudes radially from the bearing housing 3. A protrusion 5a is provided on the outer circumferential surface of the turbine housing 5. The protrusion 5a is located on the bearing housing 3 side. The protrusion 5a protrudes radially from the turbine housing 5. The bearing housing 3 and the turbine housing 5 are fastened together by a fastening mechanism 9. The fastening mechanism 9 is, for example, a G coupling. The fastening mechanism 9 clamps the protrusion 3a and the protrusion 5a.

[0026] A bearing hole 3b is formed in the bearing housing 3. The bearing hole 3b extends in the left-right direction of the supercharger TC. A bearing 13 is disposed in the bearing hole 3b. The bearing 13 is a semi-floating bearing. However, as described later, the bearing 13 may be a bearing other than a semi-floating bearing. The bearing 13 rotatably supports the shaft 15. A turbine impeller 17 is provided at the left end of the shaft 15. The turbine impeller 17 is rotatably housed in the turbine housing 5. A compressor impeller 19 is provided at the right end of the shaft 15. The compressor impeller 19 is rotatably housed in the compressor housing 7. An oil drain port 3c is formed in the lower portion of the bearing housing 3 to discharge lubricating oil scattered from the bearing 13.

[0027] An intake port 21 is formed in the compressor housing 7. The intake port 21 opens to the right of the supercharger TC. The intake port 21 is connected to an air cleaner (not shown). A diffuser flow path 23 is formed by the opposing surfaces of the bearing housing 3 and the compressor housing 7. The diffuser flow path 23 boosts the air pressure. The diffuser flow path 23 is annular in shape. The diffuser flow path 23 communicates with the intake port 21 radially inwardly via the compressor impeller 19.

[0028] A compressor scroll flow path 25 is provided in the compressor housing 7. The compressor scroll flow path 25 is formed in an annular shape. The compressor scroll flow path 25 is located, for example, at a position radially outside the shaft 15 relative to the diffuser flow path 23. The compressor scroll flow path 25 is connected to the intake port and the diffuser flow path 23 of the engine (not shown). When the compressor impeller 19 rotates, air is sucked into the compressor housing 7 from the intake port 21. The sucked air is pressurized and accelerated during the process of circulating between the impellers of the compressor impeller 19. The pressurized and accelerated air is pressurized in the diffuser flow path 23 and the compressor scroll flow path 25. The pressurized air is guided to the intake port of the engine.

[0029] An exhaust port 27 is formed in the turbine housing 5. The exhaust port 27 opens on the left side of the supercharger TC. The exhaust port 27 is connected to an exhaust gas purification device (not shown). A communication passage 29 and a turbine vortex flow path 31 are formed in the turbine housing 5. The turbine vortex flow path 31 is annular. The turbine vortex flow path 31 is located, for example, radially outward of the turbine impeller 17 relative to the communication passage 29. The turbine vortex flow path 31 is connected to a gas inlet (not shown). Exhaust gas discharged from the exhaust manifold of the engine (not shown) is guided to the gas inlet. The communication passage 29 connects the turbine vortex flow path 31 with the exhaust port 27 via the turbine impeller 17. The exhaust gas guided from the gas inlet to the turbine vortex flow path 31 is guided to the exhaust port 27 via the communication passage 29 and the turbine impeller 17. The exhaust gas guided to the exhaust port 27 rotates the turbine impeller 17 during its flow.

[0030] The rotational force of the turbine impeller 17 is transmitted to the compressor impeller 19 via the shaft 15. When the compressor impeller 19 rotates, the air pressure is increased as described above. In this way, the air is guided to the intake port of the engine.

[0031] Figure 2 is extracted Figure 1 The dotted line part of the diagram. Figure 2 As shown, a bearing structure BS is provided inside the bearing housing 3. The bearing structure BS includes a bearing hole 3b, a bearing 13, and a shaft 15.

[0032] An oil passage 3d is formed in the bearing housing 3. Lubricating oil is supplied to the oil passage 3d. The oil passage 3d opens (is connected) to the bearing hole 3b. The oil passage 3d guides the lubricating oil to the bearing hole 3b. The lubricating oil flows from the oil passage 3d into the bearing hole 3b.

[0033] A bearing 13 is arranged in the bearing hole 3b. The bearing 13 has an annular body 13a. An insertion hole 13b is formed in the body 13a. The insertion hole 13b passes through the body 13a in the axial direction of the shaft 15. The axial direction of the shaft 15 intersects with the vertical direction (specifically, is orthogonal). The shaft 15 is inserted into the insertion hole 13b. The body 13a extends in a direction intersecting with the vertical direction (specifically, is orthogonal). Hereinafter, the axial direction, radial direction and circumferential direction of the bearing 13 (that is, the axial direction, radial direction and circumferential direction of the body 13a and the shaft 15) will also be referred to as the axial direction, radial direction and circumferential direction, respectively.

[0034] Two radial bearing surfaces 13d and 13e are formed on the inner circumferential surface 13c of the body 13a (specifically, the insertion hole 13b). These two radial bearing surfaces 13d and 13e are spaced apart in the axial direction. An oil hole 13f is formed in the body 13a. This oil hole 13f extends from the inner circumferential surface 13c of the body 13a to the outer circumferential surface 13g. The oil hole 13f is located between the two radial bearing surfaces 13d and 13e. The oil hole 13f is radially opposite the opening of the oil passage 3d of the bearing 13.

[0035] The lubricating oil flows from the outer peripheral surface 13g side of the body 13a through the oil hole 13f to the inner peripheral surface 13c side. The lubricating oil flowing into the inner peripheral surface 13c side of the body 13a moves in the circumferential direction between the inner peripheral surface 13c and the shaft 15. In addition, the lubricating oil flowing into the inner peripheral surface 13c side of the body 13a moves in the axial direction ( Figure 2 Lubricating oil is supplied to the gap between shaft 15 and the two radial bearing surfaces 13d, 13e. Shaft 15 is supported by the oil film pressure of the lubricating oil. The two radial bearing surfaces 13d, 13e bear the radial load (i.e., load in the radial direction) of shaft 15.

[0036] A through-hole 13h is formed in the body 13a. The through-hole 13h extends from the inner circumferential surface 13c of the body 13a to the outer circumferential surface 13g. The through-hole 13h is located between the two radial bearing surfaces 13d and 13e. The through-hole 13h is located on the side of the body 13a opposite the side where the oil hole 13f is located. However, this is not limiting; the position of the through-hole 13h can be different from that of the oil hole 13f in the circumferential direction.

[0037] A pin hole 3e is formed in the bearing housing 3. Pin hole 3e is formed in the bearing hole 3b at a position opposite to the through hole 13h. Pin hole 3e penetrates the wall forming the bearing hole 3b. Pin hole 3e connects the interior of the bearing hole 3b with the exterior. A positioning pin 33 is inserted through pin hole 3e. Specifically, positioning pin 33 is press-fitted into pin hole 3e. The tip of positioning pin 33 is inserted into through hole 13h of the main body 13a. Positioning pin 33 restricts rotational and axial movement of the main body 13a.

[0038] The shaft 15 includes a large diameter portion 15a, a medium diameter portion 15b, and a small diameter portion 15c. The large diameter portion 15a is located closer to the turbine wheel 17 than the main body 13a (see Figure 1) side. The large diameter portion 15a is cylindrical. The outer diameter of the large diameter portion 15a is larger than the inner diameter of the inner circumferential surface 13c of the main body 13a (specifically, the radial bearing surface 13d). The outer diameter of the large diameter portion 15a is larger than the outer diameter of the outer circumferential surface 13g of the main body 13a. However, the outer diameter of the large diameter portion 15a may be equal to or smaller than the outer diameter of the outer circumferential surface 13g of the main body 13a. The large diameter portion 15a is axially opposite to the main body 13a. The large diameter portion 15a has a constant outer diameter. However, the outer diameter of the large diameter portion 15a may not be constant.

[0039] The middle diameter portion 15b is located closer to the compressor impeller 19 (see Figure 1 ) side. The middle diameter portion 15b is cylindrical in shape. The middle diameter portion 15b is inserted into the insertion hole 13b of the main body 13a. Therefore, the middle diameter portion 15b is opposite to the inner peripheral surface 13c of the insertion hole 13b in the radial direction. The middle diameter portion 15b has an outer diameter smaller than that of the large diameter portion 15a. The outer diameter of the middle diameter portion 15b is smaller than the inner diameter of the radial bearing surfaces 13d and 13e of the main body 13a. The middle diameter portion 15b has a constant outer diameter. However, the outer diameter of the middle diameter portion 15b does not have to be constant.

[0040] The small diameter portion 15c is located closer to the compressor impeller 19 (see FIG. 15c ) than the medium diameter portion 15b. Figure 1 ) side (i.e., closer to the compressor impeller 19 than the main body 13a). The small diameter portion 15c is cylindrical. The small diameter portion 15c has a smaller outer diameter than the medium diameter portion 15b. The small diameter portion 15c has a constant outer diameter. However, the outer diameter of the small diameter portion 15c does not have to be constant.

[0041] An annular oil intercepting member 35 is inserted through the small diameter portion 15c. The oil intercepting member 35 scatters the lubricating oil flowing toward the compressor impeller 19 along the shaft 15 radially outward. In other words, the oil intercepting member 35 prevents the lubricating oil from leaking toward the compressor impeller 19.

[0042] The oil intercepting member 35 has an outer diameter larger than that of the intermediate diameter portion 15b. The outer diameter of the oil intercepting member 35 is larger than the inner diameter of the inner circumferential surface 13c (specifically, the radial bearing surface 13e) of the main body 13a. The outer diameter of the oil intercepting member 35 is smaller than the outer diameter of the outer circumferential surface 13g of the main body 13a. However, the outer diameter of the oil intercepting member 35 may be equal to or larger than the outer diameter of the outer circumferential surface 13g of the main body 13a. The oil intercepting member 35 and the main body 13a are axially opposed.

[0043] The main body 13a is sandwiched in the axial direction by the oil intercepting member 35 and the large diameter portion 15a. Thrust bearing surfaces 13i and 13j are provided on the end faces of the main body 13a. The thrust bearing surface 13i is provided on the turbine impeller 17 (see Figure 1 ) side. The thrust bearing surface 13j is provided on the compressor impeller 19 (refer to Figure 1) side. Lubricating oil is supplied to the thrust bearing surface 13i via the inner circumferential surface 13c. This supplies lubricating oil to the gap between the main body 13a and the large-diameter portion 15a. Lubricating oil is supplied to the thrust bearing surface 13j via the inner circumferential surface 13c. This supplies lubricating oil to the gap between the main body 13a and the oil intercepting member 35.

[0044] If the shaft 15 is axially ( Figure 2 The load in the thrust direction (axial direction) is supported by the oil film pressure of the lubricating oil (i.e., the lubricating oil between the main body 13a and the large diameter portion 15a) supplied to the thrust bearing surface 13i. Figure 2 If the thrust bearing surface 13j moves (rightward in the figure), the oil film pressure of the lubricating oil supplied to the thrust bearing surface 13j (i.e., the lubricating oil between the body 13a and the oil intercepting member 35) supports the thrust load (axial direction). In this way, the two thrust bearing surfaces 13i and 13j bear the thrust load.

[0045] Vibration dampers 13k and 13m are formed on the outer circumferential surface 13g of the main body 13a. These dampers 13k and 13m are axially separated from each other. They are formed at opposite axial ends of the outer circumferential surface 13g. The outer diameters of these dampers 13k and 13m are larger than those of other portions of the outer circumferential surface 13g. Lubricating oil is supplied to the gap between these dampers 13k and 13m and the inner circumferential surface 3f of the bearing hole 3b. The oil film pressure of the lubricating oil dampens the vibration of the shaft 15.

[0046] Figure 3 1 is a front view showing a thrust bearing surface 13i of a bearing 13 according to the present embodiment. Figure 3 It is from Figure 2 , the thrust bearing surface 13i is viewed from the left side of FIG. The shape of the thrust bearing surface 13j is substantially identical to that of the thrust bearing surface 13i. Therefore, the description of the shape of the thrust bearing surface 13j is omitted. The shape of the radial bearing surface 13e is substantially identical to that of the radial bearing surface 13d. Therefore, the description of the shape of the radial bearing surface 13e is omitted.

[0047] like Figure 3 As shown in FIG. 1 , a plurality of arc surfaces 37 and a plurality of oil supply grooves 39 are formed on the radial bearing surface 13 d. Figure 3 In the example of FIG, the radial bearing surface 13d has four arcuate surfaces 37 and four oil supply grooves 39. However, the present invention is not limited thereto, and the number of the arcuate surfaces 37 and the oil supply grooves 39 may be other than four.

[0048] The plurality of arc surfaces 37 are separated from the shaft 15 in the radial direction. The plurality of arc surfaces 37 are arranged in a circumferential direction. The positions of the centers of curvature of the plurality of arc surfaces 37 are consistent with each other. That is, the plurality of arc surfaces 37 are located on the same cylindrical surface. However, the positions of the centers of curvature of the plurality of arc surfaces 37 may be different from each other. An oil supply groove 39 is formed between two adjacent arc surfaces 37 in the circumferential direction. The oil supply grooves 39 are formed on the radial bearing surface 13d at intervals in the circumferential direction. The oil supply grooves 39 extend in the axial direction. The shape of the flow path cross section of the oil supply groove 39 (that is, the shape in the cross section orthogonal to the axial direction) is a shape in which the circumferential width becomes thinner as it approaches the radial outer side (specifically, a triangular shape). However, the shape of the flow path cross section of the oil supply groove 39 may also be a polygonal shape other than a triangle (for example, a rectangular shape) or a semicircular shape.

[0049] The oil supply groove 39 extends from the radial bearing surface 13d to the two radial bearing surfaces 13d and 13e (see Figure 2 ) extends from the end closest to the radial bearing surface 13d and the end separating the two radial bearing surfaces 13d and 13e. The oil supply groove 39 opens into the thrust bearing surface 13i (i.e., the axial end surface of the body 13a). The oil supply groove 39 allows lubricating oil to circulate. The oil supply groove 39 supplies lubricating oil to the radial bearing surface 13d. It also supplies lubricating oil to the thrust bearing surface 13i.

[0050] As shaft 15 rotates, the lubricating oil between shaft 15 and radial bearing surface 13d moves in the rotational direction RD of shaft 15. At this time, the lubricating oil is compressed between the arcuate surface 37 of radial bearing surface 13d and shaft 15. The compressed lubricating oil presses shaft 15 radially inward (i.e., radially) (wedge effect). As a result, radial loads are supported by radial bearing surface 13d.

[0051] like Figure 3 As shown, a plurality of tapered portions 41 (specifically, tapered portions 41-1, 41-2, 41-3, and 41-4) and a pad portion 43 are formed on the thrust bearing surface 13i. The tapered portion 41 is a portion of the thrust bearing surface 13i that is recessed relative to a plane perpendicular to the axial direction. The pad portion 43 is a portion of the thrust bearing surface 13i where the tapered portion 41 is not formed (i.e., a planar portion perpendicular to the axial direction). Figure 3 In the example of FIG, the thrust bearing surface 13i has four tapered portions 41. However, the present invention is not limited thereto, and the number of tapered portions 41 may be other than four.

[0052] The tapered portion 41 is separated from the outer periphery of the thrust bearing surface 13i. A welding pad portion 43 is located radially outward of the tapered portion 41 on the thrust bearing surface 13i. The tapered portion 41 is connected to the radial bearing surface 13d. The tapered portion 41 extends circumferentially. The radial length of the tapered portion 41 is constant. However, the radial length of the tapered portion 41 does not have to be constant.

[0053] A plurality of tapered portions 41 are arranged at intervals in the circumferential direction of the main body 13a. The tapered portions 41-1, 41-2, 41-3, and 41-4 are arranged at equal intervals in sequence. However, the tapered portions 41-1, 41-2, 41-3, and 41-4 may be arranged at unequal intervals. The tapered portions 41-1 and 41-4 are formed on the upper side of the thrust bearing surface 13i in the vertical direction (specifically, the upper half in the vertical direction). The tapered portion 41-4 is closer to the uppermost portion of the thrust bearing surface 13i in the vertical direction than the tapered portion 41-1. The tapered portions 41-2 and 41-3 are formed on the lower side of the thrust bearing surface 13i in the vertical direction (specifically, the lower half in the vertical direction). The tapered portion 41-2 is closer to the lowermost portion of the thrust bearing surface 13i in the vertical direction than the tapered portion 41-3.

[0054] The tapered portion 41 communicates with the oil supply groove 39. Each of the tapered portions 41-1, 41-2, 41-3, and 41-4 communicates with one oil supply groove 39.

[0055] Figure 4 Yes Figure 3 Cross-sectional view of section AA. Figure 3 The AA section is a section passing through the tapered portion 41-2 and along the circumference of the body 13a. Figure 4 , the cross-sectional shape along the circumferential direction of the tapered portion 41-2 is shown. As will be described later, the tapered portion 41-2 is provided with an oil drain groove 45. On the other hand, the tapered portions 41-1, 41-3, and 41-4 are not provided with oil drain grooves 45. The shapes of the tapered portions 41-1, 41-3, and 41-4 are substantially identical to those of the tapered portion 41-2, except for the presence or absence of the oil drain grooves 45. Therefore, the description of the shapes of the tapered portions 41-1, 41-3, and 41-4 will be omitted.

[0056] like Figure 4 As shown in FIG. 1 , the tapered portion 41 becomes shallower as it advances in the circumferential direction (specifically, the rotational direction RD of the shaft 15). The tapered portion 41 is inclined at a constant inclination angle relative to the circumferential direction. However, the inclination angle of the tapered portion 41 may also be different depending on the circumferential position. The lubricating oil supplied to the thrust bearing surface 13i moves in the rotational direction RD of the shaft 15 as the shaft 15 rotates. At this time, the lubricating oil is moved between the tapered portion 41 of the thrust bearing surface 13i and the large diameter portion 15a (see FIG. 1 ). Figure 2 ). The compressed lubricating oil presses the large-diameter portion 15a axially (i.e., in the thrust direction) (wedge effect). This facilitates the generation of oil film pressure, increasing the load resistance in the thrust direction generated by the thrust bearing surface 13i.

[0057] like Figure 3 and Figure 4As shown, an oil drain groove 45 is provided on the thrust bearing surface 13i. The oil drain groove 45 passes through one of the tapered portions 41-2 among the multiple tapered portions 41. The oil drain groove 45 connects the oil supply groove 39 (specifically, the oil supply groove 39 connected to the tapered portion 41-2) to the outer periphery of the thrust bearing surface 13i. Lubricating oil supplied to the thrust bearing surface 13i flows through the oil drain groove 45 and is discharged from an opening 45a on the outer periphery of the thrust bearing surface 13i (hereinafter referred to as the opening 45a on the outer periphery of the oil drain groove 45). By discharging the lubricating oil supplied to the thrust bearing surface 13i from the thrust bearing surface 13i, the oil drain groove 45 promotes the flow of lubricating oil on the thrust bearing surface 13i. This suppresses the temperature increase of the oil film formed on the thrust bearing surface 13i and the decrease in viscosity associated with the temperature increase. Consequently, a decrease in the load resistance in the thrust direction generated by the thrust bearing surface 13i can be suppressed.

[0058] The oil drain groove 45 extends in the radial direction of the body 13a. However, the oil drain groove 45 may also extend in a direction inclined relative to the radial direction of the body 13a. The oil drain groove 45 is provided in the oil drain port 3c of the bearing housing 3 in the thrust bearing surface 13i (see FIG. Figure 1 ) side. As a result, the lubricating oil is scattered from the bearing 13 toward the oil discharge port 3c, and the discharge of the lubricating oil through the bearing housing 3 is smoothed. From the perspective of smooth discharge of the lubricating oil, for example, when the bearing 13 is viewed in the axial direction of the body 13a, the oil discharge port 3c of the bearing housing 3 (see Figure 1 ) is located on the extension line of the oil drain groove 45.

[0059] The cross-sectional shape of the oil drain groove 45 (i.e., the shape of the cross section perpendicular to the extending direction of the oil drain groove 45) is rectangular. However, the cross-sectional shape of the oil drain groove 45 may be a polygonal shape (e.g., a triangle) or a semicircular shape other than a rectangle.

[0060] exist Figure 3 and Figure 4 In the example, the oil drain groove 45 is connected to the end portion of the tapered portion 41-2 on the rotation direction RD side (specifically, Figure 4 However, the positional relationship between the tapered portion 41-2 and the oil drain groove 45 is not limited to Figure 3 as well as Figure 4 For example, the oil drain groove 45 may pass through the end portion of the tapered portion 41 - 2 on the rotation direction RD side.

[0061] As described above, in the bearing 13 according to this embodiment, multiple tapered portions 41 are provided on the thrust bearing surface 13i. This facilitates the generation of oil film pressure, increasing the load resistance in the thrust direction generated by the thrust bearing surface 13i. However, if an oil drain groove 45 is provided in each of the multiple tapered portions 41, the flow of lubricating oil in the thrust bearing surface 13i is excessively promoted, resulting in an excessive amount of lubricating oil discharged from the bearing 13. Consequently, the oil seal in the supercharger TC is reduced.

[0062] On the other hand, in the bearing 13 according to this embodiment, the oil drain groove 45 is provided only on one tapered portion 41-2 among the multiple tapered portions 41. This prevents the amount of lubricating oil discharged from the bearing 13 from becoming excessive, thus suppressing a decrease in oil sealing performance. In summary, by promoting the flow of lubricating oil in the thrust bearing surface 13i, it is possible to suppress a rise in the temperature of the oil film and the decrease in viscosity associated with this temperature increase. Consequently, it is possible to suppress a decrease in the thrust load capacity generated by the thrust bearing surface 13i. As described above, according to this embodiment, the thrust load capacity of the bearing 13 can be appropriately improved.

[0063] Here, the larger the flow path cross-sectional area of ​​the opening 45a on the outer peripheral edge of the oil drain groove 45, the greater the amount of lubricating oil discharged from the opening 45a. On the other hand, the smaller the flow path cross-sectional area of ​​the opening 45a on the outer peripheral edge of the oil drain groove 45, the smaller the amount of lubricating oil discharged from the opening 45a. Therefore, from the perspective of more appropriately balancing the need to suppress a decrease in oil sealing performance in the supercharger TC and the need to suppress a decrease in viscosity associated with an increase in the temperature of the oil film on the thrust bearing surface 13i, it is preferable to optimize the flow path cross-sectional area of ​​the opening 45a on the outer peripheral edge of the oil drain groove 45.

[0064] Figure 5 It is from Figure 3 The bearing 13 is viewed in the direction of arrow B. Specifically, Figure 5 This is a diagram showing the tapered portion 41-2 viewed from the radially outer side of the outer peripheral edge of the thrust bearing surface 13i. Figure 5 In the example shown, the opening 45a on the outer peripheral edge of the oil drain groove 45 is rectangular. Therefore, the flow path cross-sectional area of ​​the opening 45a on the outer peripheral edge of the oil drain groove 45 is determined by the width W (i.e., the circumferential length) and depth H (i.e., the axial length) of the opening 45a. In other words, the flow path cross-sectional area of ​​the opening 45a is determined by setting the width W and depth H of the opening 45a.

[0065] Figure 6It is a graph showing the relationship between the ratio S2 / S1 of the flow path cross-sectional area S2 of the opening 45a on the outer peripheral side of the oil drain groove 45 in the bearing 13 according to this embodiment to the area S1 of the thrust bearing surface 13i (specifically, the axial projection area of ​​the thrust bearing surface 13i) and the flow rate Q1 [L / min] of the lubricating oil discharged from the bearing 13. Figure 6 This is a curve graph obtained through numerical analytical simulation.

[0066] like Figure 6 As shown, the higher the ratio S2 / S1, the larger the flow rate Q1. As described above, in the present embodiment, a plurality of tapered portions 41 are provided on the thrust bearing surface 13i, so that the load resistance in the thrust direction becomes larger. Here, the larger the flow rate Q1, the more effectively the flow of lubricating oil in the thrust bearing surface 13i is promoted. Therefore, the temperature rise of the oil film and the decrease in viscosity caused by the temperature rise are effectively suppressed, and the load resistance in the thrust direction is effectively increased. However, generally, in thrust bearings, in order to ensure oil sealing, the flow rate Q1 is required to be less than about 0.8 [L / min] (for example, in Figure 6 (The degree is indicated by the dotted horizontal line in the figure). Figure 6 , when the ratio S2 / S1 is 0.01 or less, the flow rate Q1 is smaller than approximately 0.8 [L / min]. In other words, it can be seen that when the ratio S2 / S1 is 0.01 or less, the deterioration of the oil sealing performance is appropriately suppressed.

[0067] Here, even if an oil drain groove 45 is provided in each of the multiple tapered portions 41, the flow rate Q1 of the lubricating oil discharged from the bearing 13 can be adjusted by adjusting the opening 45a of each oil drain groove 45. However, there is a limit to the minimum amount of lubricating oil discharged from each oil drain groove 45. Furthermore, the presence of an oil drain groove 45 at a position different from the oil drain port 3c of the bearing housing 3 can lead to a decrease in oil sealing performance. Therefore, by limiting the number of oil drain grooves 45 to one, as in this embodiment, the flow rate Q1 can be appropriately reduced to appropriately suppress the degree of degradation in oil sealing performance. Furthermore, by locating the oil drain groove 45 on the thrust bearing surface 13i, closer to the oil drain port 3c of the bearing housing 3, oil sealing performance can be further improved.

[0068] Figure 7 Graph showing the relationship between the ratio S2 / S1 of the flow path cross-sectional area S2 of the opening 45a on the outer peripheral side of the oil drain groove 45 to the area S1 of the thrust bearing surface 13i in the bearing 13 according to this embodiment and the temperature T1 [°C] of the oil film formed on the thrust bearing surface 13i. Figure 7 This is a curve graph obtained through numerical analytical simulation.

[0069] like Figure 7As shown, the higher the ratio S2 / S1, the lower the temperature T1. As described above, the higher the ratio S2 / S1, the greater the flow rate Q1, which effectively promotes the flow of lubricating oil in the thrust bearing surface 13i. As a result, the increase in the temperature T1 of the oil film and the decrease in viscosity caused by the increase in temperature T1 are effectively suppressed, and the load resistance in the thrust direction is effectively increased. Here, in general, in order to ensure the load resistance in the thrust direction in the thrust bearing, the temperature T1 is required to be below 170 [℃]. According to Figure 7 The graph shows that when the ratio S2 / S1 is 0.003 or greater, the temperature T1 is 170°C or less. In other words, it can be seen that when the ratio S2 / S1 is 0.003 or greater, the decrease in the viscosity of the oil film associated with the temperature increase is appropriately suppressed, and the decrease in the load resistance in the thrust direction generated by the thrust bearing surface 13i is appropriately suppressed.

[0070] As described above, from the viewpoint of more appropriately achieving both suppression of degradation of oil sealing performance in the supercharger TC and suppression of viscosity reduction due to temperature increase of the oil film on the thrust bearing surface 13i, the ratio S2 / S1 is particularly preferably not less than 0.003 and not more than 0.01.

[0071] While the embodiments of the present disclosure have been described above with reference to the accompanying drawings, it goes without saying that the present disclosure is not limited to these embodiments. It is obvious that those skilled in the art can conceive of various variations or modifications within the scope of the claims, which naturally also fall within the technical scope of the present disclosure.

[0072] In the above description, an example in which the bearing 13 is provided in the turbocharger TC has been described. However, the bearing 13 may be provided in a device other than the turbocharger TC (for example, a ship or the like).

[0073] In the above description, an example in which the bearing 13 is a semi-floating bearing has been described. However, the bearing 13 may be a bearing other than a semi-floating bearing as long as it has a thrust bearing surface.

[0074] Explanation of symbols

[0075] 13: Bearings

[0076] 13a: Ontology

[0077] 13i: thrust bearing surface

[0078] 13j: thrust bearing surface

[0079] 15: Axis

[0080] 39: Oil supply tank

[0081] 41: tapered part

[0082] 41-1: Conical part

[0083] 41-2: Conical part

[0084] 41-3: Conical part

[0085] 41-4: Conical part

[0086] 45: Oil drain tank

[0087] 45a: Opening

[0088] S1: Area

[0089] S2: Flow path cross-sectional area

[0090] TC: Supercharger

Claims

1. A bearing, characterized in that: have: An annular body through which the shaft is inserted; a plurality of oil supply grooves, which are provided on the inner peripheral surface of the body and extend along the axial direction of the body; a thrust bearing surface, which is provided on the end surface of the body; a plurality of tapered portions, separated from the outer peripheral edge of the thrust bearing surface and provided on the thrust bearing surface at intervals in the circumferential direction of the body, communicating with the oil supply groove and becoming shallower as they progress along the circumference; and an oil drain groove provided on the thrust bearing surface, passing through one of the plurality of tapered portions and connecting the oil supply groove with the outer peripheral edge; The oil drain groove is provided only in one of the plurality of tapered portions and is not provided in any of the tapered portions other than the one tapered portion, and is provided on a vertically lower side of the thrust bearing surface.

2. The bearing according to claim 1, characterized in that A ratio of a flow path cross-sectional area of ​​an opening on the outer peripheral edge side of the oil drain groove to an area of ​​the thrust bearing surface is 0.01 or less.

3. The bearing according to claim 1 or 2, characterized in that: A ratio of a flow path cross-sectional area of ​​an opening on the outer peripheral edge side of the oil drain groove to an area of ​​the thrust bearing surface is 0.003 or more.

4. A supercharger, characterized in that: have: The bearing according to any one of claims 1 to 3.

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