Split thrust bearing

Abstract

To provide a half-split thrust bearing which is less likely to get damaged during an operation of an internal combustion engine.SOLUTION: A half-split thrust bearing has a slide face for receiving an axial line direction force and a back face on an opposite side, and thickness of a bearing wall between the slide face and the back face is constant. A reference face vertical to the axial direction of the half-split thrust bearing is defined as a virtual plane on the slide face side of the half-split thrust bearing separated from the slide face, being parallel to a radial centerline of the slide face at a peripheral center part of the half-split thrust bearing, and having the same axial line direction distance from the reference face at both peripheral ends of the slide face. At that time, the axial line direction distance between the slide face and the reference face is maximum at the radial centerline part at any radial position, and continuously gets smaller in the peripheral direction toward the peripheral end of the slide face.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to a thrust bearing that receives an axial force of a crankshaft of an internal combustion engine.

Background Art

[0002] The crankshaft of an internal combustion engine is rotatably supported at the lower part of the cylinder block of the internal combustion engine through a main bearing formed by combining a pair of half bearings in a cylindrical shape at its journal part. One or both of the pair of half bearings are used in combination with a half thrust bearing that receives the axial force of the crankshaft. The half thrust bearing is disposed on one or both of the axial end faces of the half bearing. The half thrust bearing receives the axial force generated in the crankshaft. That is, it is arranged for the purpose of supporting the axial force input to the crankshaft when the crankshaft and the transmission are connected by a clutch or the like.

[0003] Generally, the sliding surface that receives the axial force of the half thrust bearing and the back surface on the opposite side thereof are made parallel to a plane perpendicular to the axial direction of the half thrust bearing, and the thickness between the sliding surface and the back surface is made constant. In addition, on the sliding surface side near both circumferential ends of the half thrust bearing, a thrust relief is formed in which the thickness of the bearing member becomes thinner toward the circumferential end face. Generally, the thrust relief is formed such that the length from the circumferential end face of the half thrust bearing to the sliding surface and the depth at the circumferential end face are constant regardless of the radial position. The thrust relief is formed to absorb the displacement between the end faces of the pair of half thrust bearings when assembling the half thrust bearing into the split-type bearing housing (see FIG. 10 of Patent Document 1).

[0004] Conventionally, in consideration of the bending deformation of the crankshaft during the operation of the internal combustion engine, a crowned surface having a curved surface shape is provided at least on the outer diameter side of the sliding surface of the half thrust bearing, thereby reducing the local contact stress between the sliding surface of the half thrust bearing and the crankshaft (Patent Document 2).

Prior Art Documents

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-201145 [Patent Document 2] Japanese Patent Publication No. 2013-19517 [Overview of the project] [Problems that the invention aims to solve]

[0006] In recent years, crankshaft diameters have been reduced to lighten internal combustion engines, resulting in lower rigidity compared to conventional crankshafts. Consequently, crankshaft deflection is more likely to occur during operation, leading to increased crankshaft vibration. This causes a particularly large inclination of the thrust collar surface relative to the sliding surface near the circumferential center of the split thrust bearing. Therefore, the sliding surface near the circumferential center of the split thrust bearing and the thrust collar surface of the crankshaft come into contact, making them susceptible to damage (fatigue).

[0007] Even if a curved crowning surface is provided on at least the outer diameter side of the sliding surface, as described in Patent Document 2, to prevent damage (fatigue) that can easily occur due to contact between the sliding surface near the circumferential center of the split thrust bearing and the thrust collar surface of the crankshaft, it is difficult to prevent damage (fatigue) that can occur, especially when the vibration due to the deflection of the crankshaft is large, as the sliding surface near the circumferential center of the split thrust bearing comes into contact with the thrust collar of the crankshaft.

[0008] Therefore, the object of the present invention is to address the above problems and provide a split thrust bearing that is less prone to damage (fatigue) during operation of an internal combustion engine. [Means for solving the problem]

[0009] According to one aspect of the present invention, a substantially semi-circular split thrust bearing for receiving axial forces on the crankshaft of an internal combustion engine is provided. The split thrust bearing has a sliding surface that receives axial forces and a back surface on the opposite side, and the bearing wall thickness between the sliding surface and the back surface is constant. The reference plane perpendicular to the axial direction of a split thrust bearing is defined as follows: The reference plane is defined as a virtual plane located on the sliding surface side of the split thrust bearing, spaced apart from the sliding surface, parallel to the radial centerline of the sliding surface at the circumferential center of the split thrust bearing, and having the same axial distance from the reference plane at both circumferential ends of the sliding surface. Consequently, the axial distance between the sliding surface and the reference surface is maximum at the radial centerline at any radial position, and continuously decreases in the circumferential direction toward the circumferential end of the sliding surface.

[0010] According to one specific example of the present invention, the difference between the axial distance between the sliding surface and the reference surface at the radial centerline and the axial distance between the sliding surface and the reference surface at the circumferential end is 50 to 150 μm.

[0011] According to one specific example of the present invention, two thrust reliefs are formed on the sliding surface, adjacent to both circumferential ends of the split thrust bearing.

[0012] According to one specific example of the present invention, at least one oil groove is formed on the sliding surface.

[0013] According to one specific example of the present invention, the oil groove extends radially through the split thrust bearing, and the oil groove consists of a groove portion and an inclined portion. When the split thrust bearing is cut in the circumferential direction of the sliding surface, the inclined portion is adjacent to one end or both ends of the groove portion, and the wall thickness decreases from the sliding surface side towards the groove portion side. [Effects of the Invention]

[0014] According to the split thrust bearing of the present invention, even when the inclination angle of the thrust collar surface of the crankshaft with respect to the sliding surface near the circumferential center of the split thrust bearing increases due to the deflection of the crankshaft during the operation of the internal combustion engine, the sliding surfaces near both circumferential ends of the split thrust bearing come into contact with the thrust collar surface of the crankshaft. Therefore, it is possible to prevent only the sliding surface near the circumferential center of the split thrust bearing from coming into contact with the thrust collar surface of the crankshaft, and damage to the sliding surface of the split thrust bearing is unlikely to occur.

Brief Description of the Drawings

[0015] [Figure 1] It is an exploded perspective view of the bearing device. [Figure 2] It is a front view of the split bearing and the thrust bearing. [Figure 3] It is a cross-sectional view of the bearing device. [Figure 4] It is a front view of the split thrust bearing of the prior art. [Figure 5] It is a side view of the split thrust bearing of the prior art in FIG. 4 as viewed from arrow Y2. [Figure 6] It is a side view for explaining the operation of the split thrust bearing of the prior art. [Figure 7] It is a front view of the split thrust bearing of Example 1. [Figure 8] It is a cross-sectional view of the split thrust bearing of FIG. 7 taken along the line A-A. [Figure 9] It is a bottom view of the split thrust bearing of FIG. 7 as viewed from arrow Y1. [Figure 10] It is a cross-sectional view of the split thrust bearing for explaining the operation of the embodiment. [Figure 11] It is a cross-sectional view of the split thrust bearing for explaining the operation of the embodiment. [Figure 12] It is a front view of the split thrust bearing of Example 2. [Figure 13] It is a side view of the split thrust bearing of FIG. 12 as viewed from arrow Y3. [Figure 14] It is a front view of the split thrust bearing of Example 3. [Figure 15]Figure 14 is a cross-sectional view of a split thrust bearing (BB). [Figure 16] This is a front view of a split thrust bearing according to another embodiment of the present invention. [Figure 17] Figure 16 is a side view of the circumferential end of the split thrust bearing. [Modes for carrying out the invention]

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0017] (Overall configuration of the bearing device) First, the overall configuration of the bearing device 1 will be explained using Figures 1 to 3. As shown in Figures 1 to 3, the bearing housing 4, which is formed by attaching a bearing cap 3 to the lower part of the cylinder block 2, has a bearing hole (retaining hole) 5, which is a circular hole that penetrates between both sides, and annular recesses called seat seats 6, 6 are formed around the periphery of the bearing hole 5 on the side. Half-split bearings 7, 7, which rotatably support the journal portion 11 of the crankshaft, are fitted into the bearing hole 5 in a cylindrical arrangement. Half-split thrust bearings 8, 8, which receive the axial force f (see Figure 3) via the thrust collar surface 12 of the crankshaft, are fitted into the seat seats 6, 6 in an annular arrangement.

[0018] (Conventional technology) Next, we will explain the problems with the conventional split thrust bearing 18 using Figures 4 to 6. Figure 4 shows a front view of a conventional split thrust bearing 18, and Figure 5 shows a side view of the split thrust bearing 18 shown in Figure 4, viewed from the direction of arrow Y2. The sliding surface 181 and back surface 184 of the conventional split thrust bearing 18 are planes perpendicular to the axial direction of the split thrust bearing 18.

[0019] Figure 6 shows a state in which the inclination angle of the thrust collar surface 12 of the crankshaft with respect to the sliding surface 181 near the circumferential center of the conventional split thrust bearing 18 has increased due to the deflection of the crankshaft during operation of the internal combustion engine (reference numeral 186 indicates the circumferential end face). Since the sliding surface 181 and back surface 184 of the conventional split thrust bearing 18 are planar in shape perpendicular to the axial direction, when the inclination angle of the thrust collar surface 12 of the crankshaft with respect to the sliding surface 181 near the circumferential center of the split thrust bearing 18 increases, only the sliding surface 181 near the circumferential center of the split thrust bearing 18 comes into strong contact with the thrust collar surface 12 of the crankshaft, which has the problem of making the sliding surface 181 near the circumferential center prone to damage (fatigue). [Examples]

[0020] (Construction of a split thrust bearing) Next, the configuration of the split thrust bearing 8 of Embodiment 1 of the present invention will be described using Figures 7 to 11. Figure 7 shows a front view of the split thrust bearing 8, Figure 8 shows a cross-sectional view AA of the split thrust bearing shown in Figure 7, and Figure 9 shows a bottom view of the split thrust bearing 8 shown in Figure 7 from the perspective of arrow Y1. The split thrust bearing 8 of this embodiment is formed in a substantially semi-circular shape by a bimetal, in which a thin bearing alloy layer is bonded to a steel backing layer (the split thrust bearing 8 is curved in the direction perpendicular to the plane of the paper in Figure 7 as described below, so it is referred to as a "substantially" semi-circular shape). The split thrust bearing 8 has a sliding surface 81 facing in the axial direction, and the sliding surface 81 is made of a bearing alloy layer. The split thrust bearing 8 has a back surface 84 on the opposite side of the sliding surface 81.

[0021] The sliding surface 81 may have oil grooves 81a to improve the oil retention of the lubricating oil. Figures 7 and 2 show two oil grooves 81a, 81a, but unlike this embodiment, the sliding surface 81 may have one or more oil grooves 81a. However, when oil grooves 81a are formed, the "sliding surface 81" in the portion with oil grooves 81a refers to a hypothetical surface assuming that oil grooves 81a do not exist.

[0022] The sliding surface 81 is curved convexly in the circumferential direction of the split thrust bearing 8, moving from the sliding surface 81 side towards the back surface 84 side. Here, "curved" means that the sliding surface 81 is curved so as a whole that it forms a single curved surface, and the curvature of the curved surface may change in the circumferential direction (the same applies to other embodiments). The back surface 84 is parallel to the sliding surface 81. That is, the bearing wall thickness T perpendicular to the sliding surface 81 between the sliding surface 81 and the back surface 84 is constant, so the back surface 84 has a shape corresponding to the sliding surface. Note that the bearing wall thickness T may have a slight displacement (15 μm or less).

[0023] The reference plane 90 perpendicular to the axial direction of the split thrust bearing 8 is defined as follows: The line along the radial direction of the sliding surface 81 at the circumferential center C of the split thrust bearing 8 is called the radial centerline (CL). The reference surface 90 is a virtual surface in which the sliding surface 81 of the split thrust bearing 8 faces the reference surface 90, the reference surface 90 is spaced apart from the sliding surface 81, the radial centerline (CL) of the sliding surface 81 of the split thrust bearing 8 is parallel to the reference surface 90, and the axial distance L2 between the sliding surface 81 and the reference surface 90 is the same at both circumferential ends 86 of the sliding surface 81. The axial direction is perpendicular to the reference plane 90, the axis is an imaginary line that passes through the center of the half-split thrust bearing 8 and extends in the axial direction, and the axial distance refers to the axial distance between two objects.

[0024] When the reference surface 90 is defined in this way, the axial distance L between the sliding surface 81 and the reference surface 90 is maximum (L1) at the radial centerline CL at any position in the radial direction, and continuously decreases (circumferentially) toward the circumferential end 86 side (L2) of the sliding surface 81 (see Figures 8 and 9). At this time, the axial distance between the back surface 84 of the split thrust bearing 8 and the reference surface 90 is also maximum at the radial centerline at any position in the radial direction, and continuously decreases (circumferentially) toward the circumferential end side of the back surface 84. Since the sliding surface 81 and the back surface 84 are parallel, it goes without saying that the same relationship holds for the back surface 84 as well.

[0025] Specifically, when used in the crankshaft of a small internal combustion engine such as a passenger car (having a journal section with a diameter of approximately 30 to 100 mm), the difference L3 (L3 = L1 - L2) between the axial distance L1 between the sliding surface 81 and the reference surface 90 at the circumferential center C (radial centerline CL) of the split thrust bearing 8 and the axial distance L2 between the sliding surface 81 and the reference surface 90 at the circumferential end 86 is, for example, 25 to 200 μm, and more preferably 50 to 150 μm. When this difference in axial distance L3 is less than 25 μm, when the inclination angle of the thrust collar surface 12 of the crankshaft with respect to the sliding surface 81 near the circumferential center of the split thrust bearing 8 increases, the sliding surface 81 near the circumferential end no longer contacts the thrust collar surface 12 of the crankshaft, and only the sliding surface 81 near the circumferential center of the split thrust bearing 8 is more likely to contact the thrust collar surface 12. Furthermore, if this axial distance difference L3 exceeds 200 μm, the inclination angle of the thrust collar surface 12 of the crankshaft with respect to the sliding surface 81 near the circumferential center of the split thrust bearing 8 becomes large, which can cause excessive load on the sliding surface 81 near the circumferential end 86, potentially leading to damage. However, these dimensions are merely examples, and the axial distance difference L3 is not limited to this range.

[0026] In this embodiment, the split thrust bearing 8 has a radial center line CL at the circumferential center C (and the corresponding radial center line of the back surface 84) that is a straight line (i.e., flat) parallel to the reference plane 90 along its entire radial length. However, it is not limited to this, and for example, the sliding surface 81 and the back surface 84 may have a single (convex) curved shape that protrudes slightly from the back surface 84 towards the sliding surface 81 in a radial cross-sectional view at the circumferential center C and other positions, or a single (convex) curved shape that protrudes slightly from the sliding surface 81 towards the back surface 84 in a radial cross-sectional view, or other curves. When the sliding surface in the circumferential center C is curved radially, the split thrust bearing 8 is positioned such that the axial distance L1 between the radial centerline CL and the reference surface 90 at the radial outer end 8o is the same as the axial distance L1 between the radial centerline CL and the reference surface 90 at the radial inner end 8i. This position is described as "the radial centerline CL of the sliding surface 81 of the split thrust bearing 8 being parallel to the reference surface 90." In this position, the axial distance L1 of the radial centerline CL at the radial inner end 8i and the radial outer end 8o is defined as "the axial distance L1 between the sliding surface 81 and the reference surface 90 in the circumferential center C (radial centerline CL portion)."

[0027] Furthermore, in this embodiment, the split thrust bearing 8 has a sliding surface 81 (linear surface) at the circumferential end 86 (circumferential end face 83) that is parallel to the reference surface 90. However, it is not limited to this, and the sliding surface 81 (linear surface) at the circumferential end 86 (circumferential end face 83) may be slightly inclined with respect to the reference surface 90. When the sliding surface 81 (linear surface) at the circumferential end 86 (circumferential end face 83) is inclined with respect to the reference surface 90, the axial distance L2 is defined as the axial distance at the position where the axial distance L with respect to the reference surface 90 is minimized on the sliding surface 81 (linear surface) of the circumferential end 86 (circumferential end 83).

[0028] Furthermore, in the case of a split thrust bearing 8, if an oil groove 81a is formed at a position including the circumferential center C (radial centerline CL) of the sliding surface 81, the radial centerline CL is assumed on the virtual sliding surface 81 as if the oil groove 81a were not formed, and the axial distance L1 is defined as the axial distance between the virtual sliding surface 81 at the circumferential center C of the split thrust bearing 8 and the reference surface 81a.

[0029] The split thrust bearing 8 has its back surface 84 positioned on the seat 6 of the cylinder block 2, and its sliding surface 81 receives an axial force f (see Figure 3) via the thrust collar surface 12 of the crankshaft. Figure 10 is a cross-sectional view of a split thrust bearing 8 when the radial center line of the back surface 84 of the split thrust bearing 8 (the linear surface of the back surface 84 opposite to the radial center line CL of the sliding surface 81) is parallel to the seat 6 of the cylinder block 2 (contacting the seat 6), and the axial distance L4 between the back surface 84 and the seat 6 of the cylinder block 2 is the same at both circumferential ends of the back surface 84. An axial gap S2 is formed between the back surface 84 of the split thrust bearing 8 and the seat 6, which increases continuously toward the circumferential end surface 83 of the split thrust bearing 8. Furthermore, the amount of axial displacement of the sliding surface 81 of the split thrust bearing 8 in the direction in which the sliding surface 81 faces is smallest at the circumferential center C of the split thrust bearing 8, and increases continuously toward the circumferential end.

[0030] (action) Next, the operation of the split thrust bearing 8 in this embodiment will be explained using Figure 11. Figure 11 shows a state in which the inclination angle of the thrust collar surface 12 of the crankshaft with respect to the sliding surface 81 near the circumferential center of the split thrust bearing 8 has increased due to the deflection of the crankshaft during operation of the internal combustion engine. The axial displacement of the sliding surface 81 of the split thrust bearing 8 in the direction in which the sliding surface 81 faces (towards the thrust collar surface 12) continuously increases toward the circumferential end. Therefore, even when the inclination angle of the thrust collar surface 12 of the crankshaft with respect to the sliding surface 81 near the circumferential center C of the split thrust bearing 8 increases, the sliding surfaces 81 near both circumferential ends 86 come into contact with the thrust collar surface 12 of the crankshaft, thus preventing only the sliding surface 81 near the circumferential center of the split thrust bearing 8 from coming into contact with the thrust collar surface of the crankshaft. Furthermore, an axial gap S2 is formed between the back surface 84 of the split thrust bearing 8 and the seat 6, which continuously increases toward the circumferential end face 83 of the split thrust bearing 8. When the sliding surfaces 81 near both circumferential ends 86 come into contact with the thrust collar surface 12 of the crankshaft, the area near the circumferential end face 83 of the split thrust bearing 8 elastically deforms toward the gap S2, thereby reducing the axial displacement of the sliding surface 81. This prevents only the sliding surface 81 near the circumferential end 86 of the split thrust bearing 8 from coming into contact with the thrust collar surface 12 of the crankshaft. As a result, the split thrust bearing 8 of the invention is less prone to damage to the sliding surface 81. [Examples]

[0031] Using Figures 12 and 13, a different form of the split thrust bearing 8 from that of Example 1 will be described. Note that parts that are the same as or similar to those described in Example 1 will be denoted by the same reference numerals.

[0032] Figure 12 shows a front view of the split thrust bearing 8 of Example 2, looking at the sliding surface 81 side, and Figure 13 shows a side view of the split thrust bearing 8 of Figure 12 taken along the Y3 arrow.

[0033] (composition) First, let's describe the configuration. The configuration of the split thrust bearing 8 in this embodiment is generally the same as that of Embodiment 1, except for the configuration of the thrust reliefs 82, 82.

[0034] The split thrust bearing 8 of this embodiment is provided with thrust reliefs 82, 82 in regions adjacent to the end faces 83, 83 on both sides in the circumferential direction.

[0035] The thrust relief 82 is a wall thickness reduction region formed in the area adjacent to the circumferential end faces 83, 83 on the sliding surface 81 side, such that the bearing wall thickness T of the split thrust bearing 8 gradually thins towards the end face, and extends along the entire radial length of the circumferential end face 83 of the split thrust bearing 8. The thrust relief 82 is formed to mitigate the misalignment between the circumferential end faces 83, 83 of the pair of split thrust bearings 8, 8, caused by misalignment when the split thrust bearing 8 is assembled in the split bearing housing 4.

[0036] In this case as well, the sliding surface 81 includes a hypothetical surface where the oil groove 81a and thrust relief 82 portions would not exist. The sliding surface 81 is curved such that the entire surface in the circumferential direction of the split thrust bearing 8 is a single convex curved surface that extends from the sliding surface 81 toward the back surface 84.

[0037] As shown in Figure 12, the thrust relief 82 has a constant thrust relief length L5 between the radially inner end 8i and the radially outer end 8o of the split thrust bearing 8. When used in the crankshaft (journal diameter approximately 30-100 mm) of a small internal combustion engine such as those for passenger cars, the thrust relief length L5 from the circumferential end face 83 of the split thrust bearing 8 is set to 3-25 mm.

[0038] Here, the thrust relief length L5 is defined as the length measured perpendicularly from the plane (thrust bearing dividing plane HP) passing through both circumferential end faces 83 of the split thrust bearing 8. In particular, the thrust relief length L5 at the radially inner end is defined as the length perpendicular from the circumferential end face 83 of the split thrust bearing 8 to the point where the thrust relief surface 82 intersects with the sliding surface 81.

[0039] Furthermore, the thrust relief 82 of the split thrust bearing 8 can be formed such that it has a certain depth RD1 between the radially inner end 8i and the radially outer end 8o of the split thrust bearing 8 at the circumferential end face 83. The depth RD1 of the thrust relief 82 can be 0.1 to 1 mm.

[0040] Here, the depth RD1 of the thrust relief 82 refers to the distance perpendicular to the sliding surface 81 from the sliding surface 81 of the split thrust bearing 8 to the surface of the thrust relief 82. In other words, the depth is the distance measured perpendicularly from the virtual sliding surface, which is an extension of the sliding surface 81 onto the thrust relief 82, to the surface of the thrust relief 82. Therefore, the depth RD1 is specifically defined as the depth from the surface of the thrust relief 82 to the virtual sliding surface at the circumferential end face 83 of the split thrust bearing 8.

[0041] However, these dimensions of thrust relief length L5 and thrust relief depth RD1 are merely examples and are not limited to these dimensional ranges. Furthermore, the dimensions of thrust relief length L5 and thrust relief depth RD1 may be formed to vary between the radially inner end 8i and the radially outer end 8o of the split thrust bearing 8.

[0042] As described above, when a thrust relief 82 is formed, the axial distance L2 is defined as the axial distance between the virtual sliding surface and the reference surface 90 in the case where a thrust relief 82 is not formed at the circumferential end. [Examples]

[0043] Using Figures 14 and 15, a split thrust bearing 8 of a different form from that of Example 1 will be described. Note that parts that are the same as or similar to those described in Example 1 will be denoted by the same reference numerals.

[0044] Figure 14 shows a front view of the half-split thrust bearing 8 of Example 3, looking at the sliding surface 81 side, and Figure 15 shows a cross-sectional view of the half-split thrust bearing 8 of Figure 14.

[0045] (composition) First, let's describe the configuration. The configuration of the split thrust bearing 8 in this embodiment is generally the same as that of Embodiment 1, except for the configuration of the oil groove 81a and the configuration of the inclined surfaces 85F and 85R.

[0046] In this embodiment as well, the sliding surface 81 (including the oil groove 81a and the inclined surfaces 85F and 85R, which are hypothetical surfaces assuming they do not exist) is curved such that the entire surface in the circumferential direction of the split thrust bearing 8 is a single convex curved surface that moves from the sliding surface 81 toward the back surface 84.

[0047] To facilitate understanding of the configuration of the inclined surfaces 85F and 85R, the sliding surface 81 and the back surface 84 are drawn in Figure 15 to be parallel to a plane perpendicular to the axial direction of the split thrust bearing 8. The split thrust bearing 8 in this embodiment is equipped with four oil grooves 81a that extend radially from the center of the split thrust bearing on the sliding surface 81 side.

[0048] The split thrust bearing 8 is provided with inclined surfaces 85F and 85R on the sliding surface 81 side. The inclined surfaces 85F and 85R are wall thickness reduction regions formed in the area on the sliding surface 81 side adjacent to the circumferential ends 81aE, 81aE of the oil groove 81a, such that the wall thickness T of the split thrust bearing 8 gradually thins from the sliding surface 81 toward the circumferential ends 81aE, 81aE of the oil groove 81a, and has a minimum thickness T1 at the position adjacent to the circumferential ends 81aE of the oil groove 81a. These regions extend along the entire radial length of the split thrust bearing 8. The inclined surfaces 85F and 85R are formed to increase the pressure of the oil flowing in the gap between the inclined surfaces 85F, 85R and the thrust collar surface 12 during operation of the internal combustion engine, thereby increasing the load capacity of the split thrust bearing 8.

[0049] The depth D0 of the inclined surface, defined as the length perpendicular to the sliding surface 81 from the sliding surface 81 to the surface of the inclined surfaces 85F and 85R at a position adjacent to the circumferential end 81aE of the oil groove 81a, can be 5 to 80 μm. The length of each inclined surface 85F and 85R parallel to the circumferential direction of the half thrust bearing 8 can be a length corresponding to a circumferential angle of 5° to 25°. However, the dimensions of the depth D0 of these inclined surfaces and the dimensions of the lengths of the inclined surfaces are merely examples and are not limited to these dimensional ranges.

[0050] It should be noted that, without being limited to this embodiment, an inclined surface 85F may be formed only on the circumferential end 81aE on the front side in the rotational direction X (direction of the X arrow in Figure 14) of the thrust collar surface 12 of the oil groove 81a, and an inclined surface 85R may not be formed on the circumferential end 81aE on the rear side in the rotational direction X of the crankshaft (thrust collar surface 12) of the oil groove 81a.

[0051] Furthermore, in the case of a split thrust bearing 8, if an oil groove 81a or inclined surfaces 85F, 85R are formed at a position including the circumferential center C (radial centerline CL) of the sliding surface 81, the axial distance L1 is defined as the axial distance between the virtual sliding surface 81 at the circumferential center C of the split thrust bearing 8 and the reference surface 90, assuming the radial centerline CL on the virtual sliding surface 81 as if the oil groove 81a or inclined surfaces 85F, 85R were not formed. Also, in the case of a split thrust bearing 8, if an oil groove 81a is formed at a position including the circumferential end 86 of the sliding surface 81, the axial distance L2 is defined as the axial distance between the virtual sliding surface at the circumferential end 86 and the reference surface 90 as if the oil groove 81a were not formed.

[0052] While embodiments of the present invention have been described in detail above with reference to the drawings, it should be understood that the specific configuration is not limited to these embodiments, and that design modifications that do not depart from the spirit of the present invention are included in the present invention.

[0053] For example, in the embodiment, a bearing device 1 of the type in which the split bearing and the split thrust bearing are separate was described, but the present invention is not limited to this and can also be applied to a bearing device 1 of the type in which the split bearing and the split thrust bearing are integrated.

[0054] Furthermore, as shown in Figure 16, the split thrust bearing may be provided with a projection 88 that protrudes radially outward for positioning and rotation prevention. Note that the projection 88 does not necessarily have to satisfy the above-described configuration of axial distances L1 and L2 and bearing wall thickness T. Furthermore, as shown in Figures 16 and 17, the circumferential length of the split thrust bearing may be formed to be shorter by a predetermined length S1 from the position of the circumferential end face (thrust bearing splitting plane HP) of the split thrust bearing 8 shown in Example 1. In addition, the inner circumferential surface of the split thrust bearing may be cut out in an arc shape with radius R near both circumferential ends. Furthermore, a back relief 82B can be formed on the back surface 84 of the split thrust bearing and in the region adjacent to the circumferential end face 83.

[0055] Furthermore, chamfers can be formed along the circumferential direction on the sliding surface and the radially outer edge and / or radially inner edge of the split thrust bearing. In this case, the bearing wall thickness T of the split thrust bearing can be expressed by the bearing wall thickness when no chamfers are formed.

[0056] Furthermore, although the above embodiment describes a case in which four split thrust bearings are used in a bearing device, the present invention is not limited thereto, and the desired effect can be obtained by using at least one split thrust bearing according to the present invention. In addition, in a bearing device, the split thrust bearing of the present invention may be integrally formed on one or both end faces in the axial direction of a split bearing that rotatably supports a crankshaft. [Explanation of symbols]

[0057] 1. Bearing device 11 Journal Section 12 Thrust Color Surface 2 Cylinder Blocks 3 Bearing cap 4 Bearing housing 5 Bearing hole (retaining hole) 6 catch seat 7. Split bearing 71 Lubricant groove 72 Through hole 8. Split thrust bearing 81 Sliding surface 81a Oil groove 82 Thrust Relief 82B Back Relief 83 End faces in the circumferential direction 84 Back 85F Slope 85R slope 86 Both ends in the circumferential direction 88 Protrusion 90 Reference plane C Circumferential center CL Radial center line HP thrust bearing split plane L1 Axial distance L2 Axial distance L3 Difference in axial distance L4 Axial distance L5 Thrust Relief Length RD1 Thrust relief depth T Bearing wall thickness T1 Bearing wall thickness X rotation direction

Claims

1. A semicircular split thrust bearing (8) for receiving axial forces on the crankshaft of an internal combustion engine, The split thrust bearing (8) has a sliding surface (81) that receives the axial force and a back surface (84) on the opposite side, and the bearing wall thickness (T) between the sliding surface (81) and the back surface (84) is constant. The reference surface (90) of the aforementioned split thrust bearing (8) is perpendicular to the axial direction, On the sliding surface (81) side of the split thrust bearing (8), there is a space spaced apart from the sliding surface (81), If we define a virtual surface as one that is parallel to the radial center line (CL) of the sliding surface (81) at the circumferential center (C) of the split thrust bearing (8), and where the axial distance (L2) between the sliding surface (81) and the reference surface (90) is the same at both circumferential ends (86) of the sliding surface (81), then A split thrust bearing wherein the axial distance (L) between the sliding surface (81) and the reference surface (90) is maximum (L1) at the circumferential center (C) at any position in the radial direction, and continuously decreases in the circumferential direction toward the circumferential end (86) of the sliding surface (81).

2. The split thrust bearing according to claim 1, wherein the difference between the axial distance (L1) between the sliding surface (81) and the reference surface (90) at the radial center line (CL) and the axial distance (L2) between the sliding surface (81) and the reference surface (90) at the circumferential end (86) is 50 to 150 μm.

3. A split thrust bearing according to claim 1 or claim 2, wherein two thrust reliefs (82) are formed on the sliding surface (81), adjacent to the circumferential end faces (83) of the split thrust bearing (8).

4. A split thrust bearing according to claim 1 or claim 2, wherein at least one oil groove (81a) is formed on the sliding surface (81).

5. The oil groove (81a) extends radially to the split thrust bearing (8), and the oil groove (81a) consists of a groove portion and an inclined portion, and when the split thrust bearing (8) is viewed in cross-section when cut in the circumferential direction of the sliding surface (81), the inclined portion is adjacent to one end (81aE) or both ends of the groove portion, and the wall thickness decreases from the sliding surface side to the groove portion side, as described in claim 4.

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