Half-split thrust bearings

Abstract

A half-split thrust bearing is provided, which is used for a crankshaft of an internal combustion engine and can suppress the occurrence of seizure during operation. According to the present invention, a half-split thrust bearing is provided, wherein the sliding surface of the half-split thrust bearing has at least two oil grooves extending in the radial direction, a plurality of lands located on both circumferential sides of each oil groove, and at least two first inclined surfaces formed between the oil grooves and the lands so as to be located forward of the oil grooves in the rotational direction of the crankshaft, wherein the first inclined surfaces are provided with a plurality of circumferential grooves extending in the circumferential direction so as to be connected in the radial direction, and the lands are provided with a plurality of oil drain grooves arranged and extending in a manner intersecting the circumferential direction and the radial direction, wherein a plurality of flat portions are formed between the plurality of oil drain grooves, and wherein each oil drain groove opens at at least one of the radially outer end portion and the radially inner end portion of the land.

Description

Technical Field

[0001] The present invention relates to a semi-circular half-split thrust bearing having a sliding surface for receiving 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 portion of the engine's cylinder block by a main bearing composed of a pair of half-split bearings assembled into a cylindrical shape at its journal portion. One or both of the half-split bearings can be used in combination with a half-split thrust bearing that supports the axial force of the crankshaft. The half-split thrust bearing is mounted on one or both of the axially facing end surfaces of the half-split bearing.

[0003] The half-split thrust bearing supports the axial force generated in the axial direction of the crankshaft. Specifically, when the crankshaft is connected to the transmission via a clutch, the half-split thrust bearing is arranged to support the axial force input to the crankshaft.

[0004] As mentioned above, the crankshaft of an internal combustion engine is supported at its journal portion in the lower portion of the engine's cylinder block by a main bearing comprised of a pair of half-split bearings. Lubricating oil is fed from an oil return hole in the cylinder block wall through a through-hole in the main bearing wall into a lubricating oil groove formed along the inner circumference of the main bearing. This lubricating oil is then supplied to the lubricating oil groove of the main bearing and then to the half-split thrust bearing.

[0005] However, in recent years, in order to achieve lightweight internal combustion engines, the crankshaft diameter has been reduced, and the stiffness has become smaller than that of previous crankshafts. Therefore, when the internal combustion engine is running, the crankshaft is prone to bending, and the vibration of the crankshaft tends to increase. Therefore, the sliding surface of the half-split thrust bearing is in direct contact with the thrust ring surface of the crankshaft, which is prone to damage such as sintering. As a countermeasure, a technology has been proposed, in which a plurality of shoe portions are provided on the sliding surface of the half-split thrust bearing, and oil grooves and inclined surfaces are provided between the shoe portions. As a result, when the internal combustion engine is running, a high-pressure oil film is formed in the gap between the inclined surface and the thrust ring surface, making it difficult for the sliding surface of the half-split thrust bearing to directly contact the thrust ring surface of the crankshaft (for example, refer to patent document 1).

[0006] In addition, a technology has been proposed in which fine grooves extending in the circumferential direction are formed on the sliding surface of a half-split thrust bearing so as to be connected in the radial direction, and oil is supplied to the entire sliding surface to prevent seizure of the sliding surface (for example, see Patent Document 2).

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-172607

[0010] Patent Document 2: Japanese Patent Application Laid-Open No. 2001-323928 Summary of the Invention

[0011] Technical problem to be solved by the invention

[0012] However, even if the technologies of Patent Documents 1 and 2 are adopted, if the vibration time (vibration duration) of the above-mentioned crankshaft is long, the oil flowing in the gap between the sliding surface of the half-split thrust bearing and the thrust ring surface of the crankshaft becomes hot, and this heat is transferred, causing the sliding surface (pad portion) to become hot, so it is difficult to prevent the sintering of the half-split thrust bearing.

[0013] Therefore, an object of the present invention is to provide a half-split thrust bearing for a crankshaft of an internal combustion engine, which can suppress the occurrence of seizure during operation of the internal combustion engine.

[0014] Technical solutions used to solve technical problems

[0015] According to the present invention, a half-split thrust bearing is provided. The half-split thrust bearing is a half-split thrust bearing in a semi-circular ring shape and is used to withstand the axial force of the crankshaft of an internal combustion engine, wherein:

[0016] A half-split thrust bearing has a sliding surface that bears axial force and a back surface on the opposite side. The axial, circumferential, and radial directions are specified. Furthermore, the sliding surface has:

[0017] at least two oil grooves, each extending radially from a radially inner end portion to a radially outer end portion of the sliding surface;

[0018] A plurality of lands, the plurality of lands being located on both sides of the circumference of each oil groove, and having a constant thickness from the back surface to the axial direction of the land; and

[0019] At least two first inclined surfaces, each first inclined surface is formed between the oil groove and the shoe surface in a manner such that it is located forward of the oil groove in the rotation direction of the crankshaft, and the axial thickness of each first inclined surface from the back surface to the first inclined surface gradually decreases in the circumferential direction from the shoe surface side toward the oil groove side.

[0020] in,

[0021] A plurality of circumferential grooves extending in the circumferential direction are formed on the first inclined surface so as to be connected in the radial direction.

[0022] A plurality of oil drain grooves are formed on the shoe surface, and the plurality of oil drain grooves are arranged and extended in a manner intersecting the circumferential direction and the radial direction. A plurality of flat portions parallel to the back surface are formed between the plurality of oil drain grooves, and each oil drain groove opens at at least one of the radially outer end portion and the radially inner end portion of the shoe surface.

[0023] According to the present invention, the groove depth D2 of the circumferential groove formed on the first inclined surface may be 1 to 10 μm, and the groove width W2 of the circumferential groove formed on the first inclined surface may be 0.05 to 0.3 mm.

[0024] In addition, according to the present invention, the sliding surface may also have at least two second inclined surfaces, each second inclined surface is formed between the oil groove and the shoe surface in a manner that is located on the rear side of the rotation direction of the crankshaft relative to the oil groove, and the axial thickness of each second inclined surface from the back side to the second inclined surface gradually becomes thinner along the circumferential direction from the shoe surface side to the oil groove side, and a plurality of circumferential grooves extending in the circumferential direction are formed on the second inclined surface in a manner that is connected in the radial direction.

[0025] According to the present invention, the groove depth D2 of the circumferential groove formed on the second inclined surface may be 1 to 10 μm, and the groove width W2 of the circumferential groove formed on the second inclined surface may be 0.05 to 0.3 mm.

[0026] According to the present invention, the groove depth D3 of the oil drain groove may be 2 to 20 μm, and the groove width W3 of the oil drain groove may be 0.1 to 0.5 mm. In addition, the plurality of oil drain grooves may be arranged at a pitch P1 of 0.2 to 1 mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is an exploded perspective view of the bearing assembly.

[0028] Figure 2 This is a front view of a half-split thrust bearing according to one embodiment of the present invention.

[0029] Figure 3 It is along Figure 2 Cross-sectional view of line AA of a half-split thrust bearing.

[0030] Figure 4 It is along Figure 2 Cross-sectional view of line BB of a half-split thrust bearing.

[0031] Figure 5 Yes Figure 2 An enlarged view of the pad surface within the dotted circle A1 of the half-split thrust bearing.

[0032] Figure 6 It is along Figure 5 Cross-sectional view of the tile surface along line CC.

[0033] Figure 7This is a front view of a bearing assembly including a half-split bearing and a thrust bearing.

[0034] Figure 8 It is a cross-sectional view of the bearing assembly.

[0035] Figure 9A It is a figure for demonstrating the effect|action of this invention.

[0036] Figure 9B It is a figure for demonstrating the effect|action of this invention.

[0037] Figure 10A It is a diagram for explaining the operation of the conventional technology.

[0038] Figure 10B It is a diagram for explaining the operation of the conventional technology.

[0039] Figure 11 This is a front view of a half-split thrust bearing according to another embodiment of the present invention.

[0040] Figure 12 It is along Figure 11 Cross-sectional view of line DD of a half-split thrust bearing.

[0041] Explanation of symbols

[0042] 1 bearing device

[0043] 2-cylinder block

[0044] 3 bearing caps

[0045] 4 bearing housing

[0046] 5 bearing holes

[0047] 6 sockets

[0048] 7 half-split bearings

[0049] 11 Shaft neck

[0050] 12 thrust ring

[0051] 71 lubrication oil tank

[0052] 72 through holes

[0053] 73 squeeze release part

[0054] 8 half-split thrust bearings

[0055] 81 sliding surface

[0056] 81a oil tank

[0057] 82 back

[0058] 83 circumferential end face

[0059] 84 tiles

[0060] 84i radial inner end

[0061] 84° radial outer end

[0062] 84G oil drain tank

[0063] 84S flat part

[0064] 85 tilted face

[0065] 85F first inclined surface

[0066] 85R second inclined surface

[0067] 85G circumferential groove

[0068] 85S first inclined surface and second inclined surface

[0069] Top of 85P circumferential groove

[0070] D0 Depth of the first inclined surface and the second inclined surface

[0071] D1 oil groove depth

[0072] D2 circumferential groove depth

[0073] D3 oil drain groove depth

[0074] P1 oil drain groove spacing

[0075] Axial thickness of T tile surface

[0076] T1 Minimum axial thickness of the first and second inclined surfaces

[0077] W1 oil groove width

[0078] W2 circumferential groove width

[0079] W3 oil drain groove width

[0080] X crankshaft rotation direction DETAILED DESCRIPTION

[0081] Hereinafter, the embodiments of the present invention and its advantages will be described in detail with reference to the attached schematic drawings. In addition, the embodiments shown below are only examples and do not limit the present invention.

[0082] (Overall structure of the bearing unit)

[0083] First, use Figure 1 、 Figure 7 as well as Figure 8The overall structure of the bearing device 1 including the half-split thrust bearing 8 of the present invention will be described. Figure 1 、 Figure 7 and Figure 8 As shown, the bearing housing 4 formed by mounting the bearing cover 3 on the lower part of the cylinder block 2 is formed with a circular hole, i.e., a bearing hole (retaining hole), which passes through the two side surfaces. Annular recesses, i.e., bearing seats 6, 6, are formed on the periphery of the bearing hole 5 on the side surface. The half-split bearings 7, 7, which support the journal 11 of the crankshaft in a freely rotatable manner, are combined into a cylindrical shape and fitted into the bearing hole 5. The thrust ring 12 of the crankshaft is subjected to the axial direction force f (refer to Figure 8 )'s half-split thrust bearings 8, 8 are combined into a circular ring shape and embedded in the seats 6, 6.

[0084] like Figure 7 As shown, a lubricating oil groove 71 is formed on the inner circumferential surface of the half-split bearing 7 on the cylinder block 2 side (upper side) of the main bearing. Furthermore, a through-hole 72 is formed extending from the lubricating oil groove 71 to the outer circumferential surface. Alternatively, the lubricating oil groove 71 can be formed on both the upper and lower half-split bearings. Furthermore, squeeze relief portions 73 are formed at both circumferential ends of the half-split bearing 7, adjacent to the contact surfaces of the half-split bearings 7.

[0085] In the bearing device 1, pressurized oil discharged from an oil pump (not shown) flows from the internal oil passage of the cylinder block 2 through a through-hole 72 penetrating the wall of the half-split bearing 7, and is supplied to the lubricating oil groove 71 on the inner circumferential surface of the half-split bearing 7. A portion of the oil supplied to the lubricating oil groove 71 is supplied to the inner circumferential surface of the half-split bearing 7. A portion enters an opening in the internal flow passage of the crankshaft (not shown) on the surface of the journal 11 and is delivered to the crankpin. A portion passes through the gap between the surface of the squeeze relief portion 73 of the pair of half-split bearings 7, 7 constituting the main bearing, and the surface of the journal 11 of the crankshaft, and flows outward from both ends of the half-split bearing 7, 7 in the width direction. The oil flowing outward from both ends of the half-split bearing 7 in the width direction flows into the gap primarily defined by the surface of the crankshaft thrust ring 12, the retainer 6 of the housing, the inner diameter surface of the half-split thrust bearing 8, and the surface of the journal 11 of the crankshaft, and then flows into the oil groove 81a on the sliding surface 81 of the half-split thrust bearing 8. The oil flowing into the oil groove 81 a flows along the surface of the rotating thrust collar 12 in sequence toward the first inclined surface 85F and the land surface 84 of the sliding surface 81 of the half-split thrust bearing 8 .

[0086] Generally speaking, in a thrust bearing, pressure is generated in the oil between the sliding surface 81 thereof and the surface of the thrust ring 12 of the crankshaft, and therefore the thrust bearing supports the axial force f from the crankshaft.

[0087] When the internal combustion engine is running, if the vibration caused by the bending of the crankshaft becomes larger, the surface of the crankshaft thrust ring 12 will change its inclination angle relative to the sliding surface 81 of the half-split thrust bearing, or will fluctuate while repeating the movement of approaching and moving away.

[0088] Here, using Figure 10A and Figure 10B , the structure and function of a conventional half-split thrust bearing 18 having a plurality of inclined surfaces and pad surfaces on a sliding surface will be described. Figure 10A This is a front view of the sliding surface side of the half-split thrust bearing 18. Figure 10B yes Figure 10A In the view directed toward the Y2 arrow, the X arrow indicates the rotation direction of the thrust ring 12, and the white arrow indicates the flow of oil.

[0089] The sliding surface of a conventional half-split thrust bearing 18 includes multiple lands 184, multiple inclined surfaces 185, and multiple oil grooves 81a. Each land 184 is formed so that its axial thickness remains constant between the land 184 and the back surface of the half-split thrust bearing 18. Furthermore, each oil groove 81a is formed between the lands 184, extending radially from the center of the half-split thrust bearing 18. The multiple inclined surfaces 185 include a first inclined surface 185F and a second inclined surface 185R. The first inclined surface 185F is formed so that its axial thickness gradually decreases from the circumferential end of the land 184, located rearward of the crankshaft's rotational direction X, toward the oil groove 81a. The second inclined surface 185R is formed so that its axial thickness gradually decreases from the circumferential end of the land 184, located forward of the crankshaft's rotational direction X, toward the oil groove 81a. The land 184, the first inclined surface 185F, and the second inclined surface 185R are all flat. A wedge-shaped gap is formed between the first inclined surface 185F and the surface of the thrust collar 12. The gap of the wedge-shaped gap gradually narrows toward the front side in the rotation direction X of the thrust collar 12 (see FIG. Figure 10B ).

[0090] In the conventional half-split thrust bearing 18, when the vibration caused by the deflection of the crankshaft during operation of the internal combustion engine increases and the surface of the crankshaft thrust ring 12 approaches the sliding surface, the oil located between the oil groove 81a, the first inclined surface 185F, the second inclined surface 185R, and the surface of the thrust ring 12 flows along with the surface of the thrust ring 12 to be rotated toward the circumferential end of the wedge-shaped gap between the first inclined surface 185F and the surface of the thrust ring 12, which is on the front side of the rotation direction X. When the oil flows through the wedge-shaped gap, it is subjected to the action of fluid dynamics and its pressure increases. Near the circumferential end of the wedge-shaped gap ( Figure 10A The dotted ellipse A2 and Figure 10BA high-pressure oil film reaching the highest pressure is formed near the dotted circle A2, so the sliding surface is not easy to contact the surface of the thrust ring 12 of the crankshaft.

[0091] However, if the crankshaft vibrates significantly for a long period of time during engine operation, the oil flowing through the gap between the sliding surface of the half-split thrust bearing 18 and the surface of the crankshaft thrust ring 12 in the conventional half-split thrust bearing 18 will reach a higher temperature. This heat is transferred, causing the sliding surface (land surface 184) to reach a higher temperature. Furthermore, the viscosity of the oil decreases, resulting in insufficient pressure in the oil film formed in the wedge-shaped gap. Consequently, the sliding surface (land surface 184) of the half-split thrust bearing 18 and the surface of the crankshaft thrust ring 12 are more likely to come into direct contact, which can easily cause seizure in the half-split thrust bearing 18.

[0092] The reason will be described in detail below.

[0093] As the oil flows through the wedge-shaped gap between the first inclined surface 185F and the surface of the thrust ring 12, it is subjected to fluid dynamics, causing its pressure to increase and its temperature to rise. The heated oil then flows circumferentially along the surface of the rotating thrust ring 12 through the gap between the shoe surface 184 and the surface of the thrust ring 12. It then flows through the second inclined surface 185R, located to the rear of the thrust ring 12 in the direction of rotation, the oil groove 81a, and further through the gap between the first inclined surface 185F and the surface of the thrust ring 12. Here, as the oil flows through the wedge-shaped gap between the first inclined surface 185F and the surface of the thrust ring 12, it is again subjected to fluid dynamics, causing its temperature to rise. This repeated fluid dynamics causes the oil to repeatedly rise in temperature, reaching an even higher temperature. The heat of the oil is transferred to the bearing material of the pad surface, causing the pad surface to also reach a high temperature. Furthermore, the viscosity of the oil decreases, reducing the pressure of the oil film formed in the wedge-shaped gap between the first inclined surface 185F and the surface of the thrust collar 12. This facilitates contact between the pad surface 184 and the surface of the crankshaft thrust collar 12. Consequently, damage (seizure) is more likely to occur on the pad surface 184 of the half-split thrust bearing 18.

[0094] The present invention is intended to address the above-mentioned technical problems of the prior art. Hereinafter, an example of the structure of a half-split thrust bearing of the present invention will be described.

[0095] (Structure of a half-split thrust bearing)

[0096] Figures 2 to 8The structure of a half-split thrust bearing 8 according to a first embodiment of the present invention is shown in FIG. The half-split thrust bearing 8 is formed into a semi-circular flat plate by bonding a thinner bearing alloy layer to a steel back metal layer (Japanese: lining metal layer). The half-split thrust bearing 8 has a sliding surface 81 and a back metal layer 82. The sliding surface 81 is the surface of the bearing alloy layer and supports the thrust ring 12, and the back metal layer 82 is the surface of the back metal layer opposite to the side to which the bearing alloy layer is bonded. The sliding surface 81 has a plurality of lands 84, a plurality of inclined surface portions 85, and a plurality of oil grooves 81a. Furthermore, the surface of the oil groove 81a may not be covered by the bearing alloy layer.

[0097] Figure 2 1 is a front view of a half-split thrust bearing 8 according to a first embodiment of the present invention. Figure 3 Shown along Figure 2 The cross section of line CC.

[0098] Among the multiple lands 84, the axial thickness T between the lands 84 and the back surface 82 is constant (i.e., the lands 84 are parallel to the back surface 82). The lands 84 are partially annular in shape. In this embodiment, three lands 84 are circumferentially spaced apart on the sliding surface 81 of the half-split thrust bearing 8. However, the number of lands 84 may be greater than three; generally, three to five lands are formed.

[0099] A plurality of oil grooves 81a are arranged between the lands 84 so as to extend radially (i.e., radially) from the radially inner end portions of the half-split thrust bearing 8 to the radially outer end portions. Furthermore, in this embodiment, in addition to the two oil grooves 81a sandwiched between the lands 84, partial oil grooves 81a are formed adjacent to the circumferential end surfaces 83, 83 of the half-split thrust bearing 8, so that oil grooves 81a are formed at each abutting portion when the two half-split thrust bearings 18 are assembled.

[0100] As specific dimensions of the oil groove 81a, when used in a crankshaft of a small internal combustion engine (with a diameter of the journal portion of approximately 30 to 100 mm) for a passenger car or the like, the groove width W1 of the oil groove 81a may be 2 to 7 mm, and the depth D1 of the oil groove 81a may be 0.2 to 1 mm. In this embodiment, the circumferential cross-section thereof is approximately in the shape of a circular arc (see FIG. 1 ). Figure 3 Here, the depth D1 of the oil groove 81a is defined as the length in the axial direction of the half-split thrust bearing 8 from the pad surface 84 to the deepest part of the oil groove 81a. The above dimensions are merely examples, and the dimensions are not limited to the above ranges.

[0101] An inclined surface 85 is arranged between the shoe surface 84 and the oil groove 81a. The inclined surface 85 has a first inclined surface 85F and a second inclined surface 85R, wherein the first inclined surface 85F is formed so that its axial thickness becomes thinner from the circumferential end portion of the shoe surface 84 on the rear side of the rotation direction X of the crankshaft toward the oil groove 81a, and reaches a minimum thickness T1 at a position adjacent to the oil groove 81a, and the second inclined surface 85R is formed so that its axial thickness becomes thinner from the circumferential end portion of the shoe surface 84 on the front side of the rotation direction X of the crankshaft toward the oil groove 81a, and reaches a minimum thickness T1 at a position adjacent to the oil groove 81a. In this embodiment, the first inclined surface 85F and the second inclined surface 85R are both formed as planes. Figure 2 In FIG. 1 , the X arrow indicates the rotation direction of the crankshaft (the surface of the thrust collar 12 ).

[0102] In addition, the thrust ring is relative to the Figure 8 The rotation direction of the half-split thrust bearings 8, 8 on the seat 6 on the left side of the drawing and the thrust ring surface are opposite to the rotation direction X of the half-split thrust bearings 8, 8 on the seat 6 on the right side of the drawing. Figure 2 and Figure 7 In the half-split thrust bearing 8 on the side opposite to the rotation direction (counterclockwise) of the thrust ring 12 shown, Figure 2 and Figure 7 The first inclined surface 85F shown is configured as the second inclined surface 85R. Figure 2 and Figure 7 The second inclined surface 85R shown is configured as the structure of the first inclined surface 85F.

[0103] A plurality of circumferential grooves 85G extending in the circumferential direction of the half-split thrust bearing 8 are formed on the surfaces of the first inclined surface 85R and the second inclined surface 85R. These circumferential grooves 85G are formed on the first inclined surface 85F and the second inclined surface 85R so as to be connected in the radial direction. Therefore, no flat portion is formed between the circumferential grooves 85G (see FIG. Figure 4 The surface 85S of the first inclined surface 85F and the second inclined surface 85R is defined as a virtual plane including the top 85P of the plurality of circumferential grooves 85G (refer to Figure 4 ).

[0104] The plurality of circumferential grooves 85G have the same groove width W2 and the same groove depth D2. Furthermore, each circumferential groove 85G is formed so that the groove width W2 and the groove depth D2 are constant throughout the longitudinal direction thereof.

[0105] The depth D0 of the first inclined surface 85F and the second inclined surface 85R can be set to 5 to 30 μm, where the depth D0 is defined as the length in the axial direction of the half-split thrust bearing 8 from the surface of the land surface 84 to the surface 85S of the first inclined surface 85F and the second inclined surface 85R adjacent to the oil groove 81a. The circumferential length of each of the first inclined surface 85F and the second inclined surface 85R in the half-split thrust bearing 8 can be set to a length corresponding to a circumferential angle of 5° to 25°.

[0106] The groove width W2 of the circumferential groove 85G can be set to 0.05 to 0.3 mm, where the groove width W2 is defined as the radial length of the half-split thrust bearing 8 between the tops 85P of adjacent circumferential grooves 85G. The groove depth D2 of the circumferential groove 85G can be set to 1 to 10 μm, where the groove depth D2 is defined as the axial length of the half-split thrust bearing 8 from the top 85P of the circumferential groove 85G to the deepest part of the circumferential groove 85G. The above dimensions are merely examples and are not limited to the above ranges.

[0107] A plurality of oil drain grooves 84G are formed on each land 84. The plurality of oil drain grooves 84G are arranged and extended in a manner intersecting the circumferential and radial directions of the half-split thrust bearing 8 (i.e., in a direction different from the circumferential and radial directions). In addition, a plurality of flat portions 84S parallel to the back surface 82 are formed between the plurality of oil drain grooves 84G. That is, each oil drain groove 84G is a groove that is recessed from the plurality of flat portions 84S (or land 84) toward the back surface 82, and extends in a manner opening at at least one of the radially outer end portion 84o or the radially inner end portion 84i of the land 84 (see FIG. 1 ). Figure 2 ).

[0108] Figure 5 yes Figure 2 An enlarged view of the tile surface 84 within the dotted circle A1, Figure 6 It is along Figure 5 The CC section is perpendicular to the longitudinal direction of the oil drain groove 84G and is located in a plane parallel to the axial direction of the half-split thrust bearing 8. On the shoe surface 84, the flat portions 84S and the oil drain grooves 84G are alternately arranged in a direction perpendicular to the longitudinal direction of the oil drain grooves 84G, and the oil drain grooves 84G do not intersect (do not contact) each other.

[0109] In the present embodiment, the oil drain groove 85G extends linearly on the shoe surface 84 , but may be formed so as to extend while being slightly curved.

[0110] The plurality of oil drain grooves 84G have the same groove width W3 and the same groove depth D3. Furthermore, each of the oil drain grooves 84G is formed so that the groove width W3 and the groove depth D3 are constant throughout the longitudinal direction thereof.

[0111] The groove width W3 of the pad surface 84 in a direction perpendicular to the longitudinal direction of the oil drain groove 84G can be set to 0.1 to 0.5 mm. Furthermore, the groove depth D3 of the oil drain groove 84G can be set to 2 to 20 μm, where the groove depth D3 is defined as the length in the axial direction of the half-split thrust bearing 8 from the pad surface 84 (or the flat portion 84S) to the deepest part of the oil drain groove 84G.

[0112] The pitch P1 between the oil drain grooves 84G can be set to 0.2 to 1 mm. Pitch P1 is defined as the length between the deepest portions of adjacent oil drain grooves 84G, perpendicular to the longitudinal direction of the oil drain grooves 84G. The above dimensions are merely examples, and the dimensions are not limited to the above ranges.

[0113] Below, using Figure 9A and Figure 9B The reason why seizure is less likely to occur in the half-split thrust bearing 8 of the present invention will be described. Figure 9A This is a front view of the sliding surface side of the half-split thrust bearing 8. Figure 9B yes Figure 9A In the view directed toward the Y2 arrow, the X arrow indicates the rotation direction of the thrust ring 12, and the white arrow indicates the flow of oil.

[0114] As described above, when the crankshaft's flexure causes vibrations to increase during engine operation, causing the surface of the crankshaft's thrust ring 12 to approach the sliding surface. The oil between the oil groove 81a, the first inclined surface 85F, the second inclined surface 85R, and the surface of the thrust ring 12 flows along the rotating surface of the thrust ring 12 toward the circumferential end of the wedge-shaped gap between the first inclined surface 85F and the surface of the thrust ring 12, on the forward side in the rotational direction X. Because the first inclined surface 85F includes a plurality of circumferential grooves 85G extending parallel to the circumference of the half-split thrust bearing 8, the oil is guided toward the circumferential grooves 85G, increasing the amount of oil flowing toward the forward side in the rotational direction of the wedge-shaped gap. Consequently, a large amount of oil is subjected to fluid dynamics near the circumferential end of the wedge-shaped gap (dashed circle A2), resulting in a higher pressure on the oil film formed near the circumferential end of the wedge-shaped gap than in conventional applications. Consequently, contact between the land 84 and the surface of the crankshaft's thrust ring 12 is less likely to occur.

[0115] When the oil flows through the wedge-shaped gap between the first inclined surface 85F and the surface of the thrust ring 12, the oil is subjected to the action of fluid mechanics and its pressure becomes higher, and at the same time, its temperature rises. In this embodiment, a plurality of oil drain grooves 84G are formed on the shoe surface 84. The plurality of oil drain grooves 84G extend in a manner intersecting the circumferential and radial directions of the half-split thrust bearing 8, and thus open at at least one of the radially outer end 8o or the radially inner end 8i of the shoe surface 84. Therefore, most of the high-temperature oil that flows into the space between the shoe surface 84 and the surface of the thrust ring 12 from the wedge-shaped gap between the first inclined surface 85F and the surface of the thrust ring 12 is guided to the oil drain grooves 85G and discharged to the outside from the radially outer end 8o or the radially inner end 8i of the shoe surface 84. Figure 9A On the other hand, the oil ( Figure 9A Therefore, in the present invention, the heat transfer of the oil, which causes the land 84 to become hot, is suppressed. Furthermore, due to the reduced viscosity of the oil, the oil film pressure formed in the wedge-shaped gap becomes insufficient, which prevents the sliding surface 81 (or land 84) of the half-split thrust bearing 8 and the surface of the crankshaft thrust ring 12 from coming into direct contact. As a result, seizure is less likely to occur in the half-split thrust bearing 8.

[0116] In addition, as described above, the (low temperature) oil flowing out from both ends in the width direction of a pair of half-split bearings 7, 7 constituting the main bearing and flowing into the gap surrounded by the surface of the thrust ring 12 of the crankshaft, the seat 6 of the bearing housing 4, the inner diameter surface of the half-split thrust bearing 8 and the surface of the journal portion 11 of the crankshaft is sequentially supplied to the second inclined surface 85R, the oil groove 81a and the gap between the first inclined surface 85F and the surface of the thrust ring 12.

[0117] Hereinafter, a non-limiting second embodiment according to another aspect of the present invention will be described.

[0118] Figure 11 This is a front view of a half-split thrust bearing 8' according to a second embodiment of the present invention. Figure 12 It is along Figure 11 A cross-sectional view taken along line DD.

[0119] exist Figure 11 and Figure 12In the illustrated embodiment, the half-split thrust bearing 8 includes only the first inclined surface 85F among the multiple inclined surface portions 85. The first inclined surface 85F is formed so that its axial thickness gradually decreases from the circumferential end portion of the land 84 on the rear side in the rotational direction of the crankshaft toward the oil groove 81a. Therefore, the second inclined surface 85R, which is provided in the first embodiment and whose axial thickness gradually decreases from the circumferential end portion of the land 84 on the front side in the rotational direction of the crankshaft toward the oil groove 81a, is not formed. The remaining structure is the same as that of the half-split thrust bearing of the first embodiment.

[0120] The above describes a specific example of the half-split thrust bearing of the present invention. In this description, a pair of half-split thrust bearings are combined to form a circular ring shape, and are used to support the axial force of the crankshaft of an internal combustion engine. However, the half-split thrust bearing of the present invention can also be used to support the axial force of the crankshaft of an internal combustion engine independently.

[0121] Furthermore, as described above, the half-split thrust bearing of the present invention can be formed using a bimetallic structure consisting of a back metal layer and a bearing alloy. However, it can also be formed using only the bearing alloy without the back metal layer. In this case, it should be understood that the surface in contact with the surface of the thrust collar 12 is the sliding surface, and the surface opposite thereto is the back surface.

[0122] Furthermore, the half-split thrust bearing of the present invention is not limited to a semi-circular ring shape having a circumferential length of 180°; it may also be a nearly semi-circular ring shape having a circumferential length slightly less than 180°. Furthermore, in the half-split thrust bearing of the present invention, the oil grooves adjacent to the circumferential end faces 83 may be replaced with inclined thrust release portions, or the bearing may not have oil grooves adjacent to the circumferential end faces 83. Furthermore, the bearing may include protrusions projecting radially outward from the outer circumferential surface of the half-split thrust bearing to prevent incorrect assembly of the half-split thrust bearing or to prevent rotation of the half-split thrust bearing. Furthermore, a small number of grooves may be formed on the shoe surface 84 that are not open at either the radially inner end 84i or the radially outer end 84o of the shoe surface 84.

Claims

1. A half-split thrust bearing, wherein the half-split thrust bearing is a half-split thrust bearing in a semi-circular ring shape, and is used to bear the axial direction force of the crankshaft of an internal combustion engine. The half-split thrust bearing has a sliding surface for receiving the axial force and a back surface on the opposite side thereof, and defines the axial direction, the circumferential direction, and the radial direction. In addition, the sliding surface has: at least two oil grooves, each of the at least two oil grooves extending radially from a radially inner end portion to a radially outer end portion of the sliding surface; A plurality of lands, wherein the plurality of lands are located on both sides of the circumference of each oil groove, and the thickness of the lands in the axial direction from the back surface to the lands is constant; as well as At least two first inclined surfaces, each first inclined surface is formed between the oil groove and the shoe surface in a manner that is located forward of the crankshaft in the rotation direction relative to the oil groove, and the axial thickness of each first inclined surface from the back surface to the first inclined surface gradually becomes thinner along the circumferential direction from the shoe surface side toward the oil groove side, It is characterized in that A plurality of circumferential grooves extending in the circumferential direction are formed on the first inclined surface so as to be connected in the radial direction. A plurality of oil drain grooves are formed on the shoe surface, and the plurality of oil drain grooves are arranged and extended in a manner intersecting the circumferential direction and the radial direction, and a plurality of flat portions parallel to the back surface are formed between the plurality of oil drain grooves, and each oil drain groove opens at at least one of the radially outer end portion and the radially inner end portion of the shoe surface.

2. The half-split thrust bearing according to claim 1, characterized in that: The groove depth (D2) of the circumferential groove formed on the first inclined surface is 1 to 10 μm, and the groove width (W2) of the circumferential groove formed on the first inclined surface is 0.05 to 0.3 mm.

3. The half-split thrust bearing according to claim 1, wherein: The sliding surface also has at least two second inclined surfaces, each of which is formed between the oil groove and the shoe surface in a manner that is located on the rear side of the rotation direction of the crankshaft relative to the oil groove, and the axial thickness of each second inclined surface from the back side to the second inclined surface gradually becomes thinner along the circumferential direction from the shoe surface side to the oil groove side, and a plurality of circumferential grooves extending in the circumferential direction are formed on the second inclined surface in a manner that is connected in the radial direction.

4. The half-split thrust bearing according to claim 3, wherein: The groove depth (D2) of the circumferential groove formed on the second inclined surface is 1 to 10 μm, and the groove width (W2) of the circumferential groove formed on the second inclined surface is 0.05 to 0.3 mm.

5. The half-split thrust bearing according to any one of claims 1 to 4, characterized in that: The groove depth (D3) of the oil drain groove is 2 to 20 μm, and the groove width (W3) of the oil drain groove is 0.1 to 0.5 mm.

6. The half-split thrust bearing according to claim 5, characterized in that: The plurality of oil drain grooves are arranged at a pitch (P1) of 0.2 to 1 mm.

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