plain bearing

Abstract

A sliding bearing in which cavitation is less likely to occur on a sliding surface. A second split bearing has an oil groove and two second inclined surface portions on an inner diameter side thereof. A surface of the second inclined surface portion includes a central region and a peripheral region. A kink is present at a boundary between the central region and the peripheral region. The central region forms a convex curve that bulges toward an outer diameter side of the second split bearing. The peripheral region forms a convex curve that bulges toward the inner diameter side. A plurality of second circumferential grooves are formed adjacently on the surface of the second inclined surface portion. A groove center line is inclined toward a center line of a width central portion of a length in an axial direction passing through the oil groove and with respect to a perpendicular line. An inclination angle of the groove in the peripheral region is smallest at an axial direction end portion of the second inclined surface portion and continuously becomes larger as it approaches the kink. An inclination angle of the groove in the central region is smallest at a position adjacent to a groove end portion of the second inclined surface portion and continuously becomes larger as it approaches the kink.

Description

Technical Field

[0001] The present invention relates to a cylindrical sliding bearing comprising a pair of split bearings and supporting the crankshaft of an internal combustion engine. Background Technology

[0002] The crankshaft of the internal combustion engine is supported at its journal by a main bearing consisting of a pair of split bearings in the lower part of the engine block. For the main bearing, lubricating oil discharged by the oil pump is delivered from an oil passage formed in the cylinder wall through a through-hole formed in the wall of the main bearing into a lubricating oil groove formed along the inner circumferential surface of the main bearing. Furthermore, a first lubricating oil passage is formed through the journal in the diametrical direction, with its two ends communicating with the lubricating oil groove of the main bearing. Additionally, a second lubricating oil passage branches off from the first lubricating oil passage in the journal and passes through the crank arm, communicating with a third lubricating oil passage formed through the crank pin in the diametrical direction. In this way, lubricating oil is supplied from the oil passage inside the cylinder wall to the lubricating oil groove formed on the inner circumferential surface of the main bearing through the through-hole. This lubricating oil then passes through the first, second, and third lubricating oil passages, and is supplied from the outlet at the end of the third lubricating oil passage to the sliding surface between the sliding surface of the crankpin and the sliding surface of the connecting rod bearing, which is composed of a pair of split bearings (see, for example, Patent Document 1). Oil is supplied between the surface of the crankshaft and the sliding surfaces of the main bearing and the connecting rod bearing.

[0003] In the past, in order to make the pressure (load) distribution on the sliding surface of the split bearing uniform, a split bearing was proposed, which includes a recess formed in such a way that the central side is more recessed than the axial end side of the split bearing (for example, see Patent Document 2 and Patent Document 3).

[0004] However, in the prior art, the recess does not have a circumferential groove on its surface, making it difficult for the lubricating oil to flow circumferentially within the recess. Therefore, cavitation in the lubricating oil easily diffuses outwards along the axial direction of the split bearing within the recess. Furthermore, the prior art recess is formed only by a convex curved surface protruding from the sliding surface toward the outer diameter side of the split bearing (as in this invention, it lacks a bend). Therefore, within the narrow recess between the crankshaft and the sliding surface of the split bearing, it is difficult to generate a flow that presses the lubricating oil containing cavitation near the axial end toward the crankshaft side, resulting in cavitation problems on the recess surface near the axial end. Existing technical documents Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 8-277831 Patent Document 2: Japanese Patent Publication No. 2013-536924. Patent Document 3: Japanese Patent Implementation License No. 2-41717 Summary of the Invention

[0006] The purpose of this invention is to provide a sliding bearing for the crankshaft of an internal combustion engine, wherein the sliding surface near the axial end of the split bearing is less prone to cavitation.

[0007] To solve the above-mentioned technical problems, the present invention provides a sliding bearing for supporting the crankshaft of an internal combustion engine to rotate freely. The sliding bearing comprises a first half-split bearing and a second half-split bearing arranged together to form a cylindrical shape. The first half-split bearing and the second half-split bearing have sliding surfaces on their inner diameter sides and back surfaces on their outer diameter sides. The back surfaces are parallel to the axial direction of the first half-split bearing and the second half-split bearing. The first half-split bearing and the second half-split bearing have circumferential end faces on both circumferential sides and axial end faces at both ends in the axial direction. The second half-split bearing… The split bearing has an oil groove on its inner diameter side, the oil groove being located between the two axial direction end faces of the second split bearing and extending circumferentially, having a constant axial direction length W1, the oil groove having groove ends at both ends in the axial direction, the sliding surface of the second split bearing having two second inclined surfaces, the second inclined surfaces being adjacent to each other over the entire circumferential length of each groove end, and having a constant axial direction length W2, the surface of the second inclined surfaces being displaced in a manner that continuously approaches the back side from each axial direction end face side toward the groove end, the surface of the second inclined surfaces including: a central region on the side adjacent to the groove end.The edge region is adjacent to the central region and located further along the axial direction end face of the second half-split bearing than the central region. A bend exists at the boundary between the central region and the edge region. In a cross-sectional view along the axial direction of the second half-split bearing, the central region forms a convex curve protruding towards the outer diameter of the second half-split bearing. In a cross-sectional view along the axial direction of the second half-split bearing, the edge region forms a convex curve protruding towards the inner diameter of the second half-split bearing. Multiple second circumferential grooves are formed adjacent to each other on the surface of the second inclined portion. A circumferential groove is formed over the entire circumferential length of the surface of the second inclined portion. Multiple second circumferential grooves are formed over the entire width of the surface of the second inclined portion. When viewed in a cross-section along the axial direction of the second split bearing, the second circumferential groove has a curved groove surface. Tops are formed between adjacent groove surfaces. The curve connecting the tops represents the surface of the second inclined portion. The groove width of the second circumferential groove is defined as the length of an imaginary straight line connecting the tops on both sides of the second circumferential groove. The groove centerline is defined as the position at the center of the length of the imaginary straight line and relative to... The line extending in the direction perpendicular to the aforementioned imaginary straight line; the groove depth of the aforementioned second circumferential groove is defined as the length from the aforementioned imaginary straight line to the position on the groove surface furthest from the imaginary straight line in the direction perpendicular to the aforementioned imaginary straight line; the position of the maximum groove depth of the aforementioned second circumferential groove is located on the groove centerline; the area enclosed by the aforementioned imaginary straight line and the aforementioned groove surface is defined as the groove cross-sectional area; the groove width, groove depth, and groove cross-sectional area of ​​the plurality of aforementioned second circumferential grooves are all the same to each other; the groove width, groove depth, and groove cross-sectional area of ​​the aforementioned second circumferential grooves are the same at any position in the circumferential direction; from the aforementioned second inclined surface... The angle between the perpendicular line extending orthogonally to the axis of the aforementioned split bearing and the center line of the aforementioned groove is defined as the groove inclination angle θ1. The center line of the groove on the surface of the second inclined portion passes through the center of the width of the oil groove along its axial direction and is inclined relative to the perpendicular line towards the circumferentially extending center line. The groove inclination angle θ1 in the edge region is smallest at the axial end of the second inclined portion and increases continuously towards the bend. The groove inclination angle θ1 in the central region is smallest at the position adjacent to the end of the groove on the second inclined surface and increases continuously towards the bend.

[0008] In another embodiment of the invention, the edge region of the second inclined surface is adjacent to the axial direction end face of the second half-split bearing.

[0009] In another embodiment of the invention, the width W2C of the central region of the second inclined face is more than 25% and less than 75% of the width W2 of the second inclined face.

[0010] In another embodiment of the present invention, the depth D2 of the second inclined face is 0.005 mm or more and 0.050 mm or less.

[0011] In another embodiment of the present invention, the groove depth D3 of the second circumferential groove is 1.5 μm or more and 10 μm or less.

[0012] In another embodiment of the present invention, the groove width W3 of the second circumferential groove is 0.05 mm or more and 0.25 mm or less.

[0013] In another embodiment of the present invention, the groove inclination angle θ1 of the second circumferential groove closest to the bend of the second inclined surface is greater than the groove inclination angle θ1 of the second circumferential groove closest to the end of the groove by a value in the range of 0.001° to 7°.

[0014] In another embodiment of the present invention, the groove inclination angle θ1 of the second circumferential groove that is closest to the bend of the second inclined surface is greater than the groove inclination angle θ1 of the second circumferential groove that is closest to the axial direction end of the second inclined surface by a value in the range of 0.001° to 7°.

[0015] In another embodiment of the present invention, the first half-split bearing has a centerline that passes through the center of the width of the first half-split bearing in the axial direction and extends circumferentially. The sliding surface of the first half-split bearing has two first inclined surfaces adjacent to the centerline. The first inclined surfaces have a constant axial length W5 from the centerline toward each axial end face and extend over the entire circumferential length of the first half-split bearing. The surface of the first inclined surfaces is displaced in a manner that continuously approaches the back surface from each axial end face toward the groove end. The surface of the first inclined surfaces includes a central region on the side adjacent to the centerline of the first half-split bearing.The edge region is adjacent to the central region and located further along the axial direction end face of the first half-split bearing than the central region. A bend exists at the boundary between the central region and the edge region. In a cross-sectional view along the axial direction of the first half-split bearing, the central region forms a convex curve protruding towards the outer diameter of the first half-split bearing. In a cross-sectional view along the axial direction of the first half-split bearing, the edge region forms a convex curve protruding towards the inner diameter of the first half-split bearing. Multiple first circumferential grooves are formed adjacent to each other on the surface of the first inclined portion. The first circumferential groove is formed over the entire circumferential length of the surface of the first inclined portion. Multiple first circumferential grooves are formed over the entire width of the surface of the first inclined portion. When viewed in cross-section along the axial direction of the first split bearing, the first circumferential groove has a curved groove surface. Tops are formed between adjacent groove surfaces. The curve formed by connecting the tops represents the surface of the first inclined portion. The groove width of the first circumferential groove is defined as the length of an imaginary straight line connecting the tops on both sides of the first circumferential groove. The groove centerline is defined as the center position passing through the length of the imaginary straight line. Furthermore, the groove depth of the first circumferential groove is defined as the length from the imaginary line to the position on the groove surface furthest from the imaginary line in the direction perpendicular to the imaginary line. The maximum groove depth of the first circumferential groove is located on the groove centerline. The area enclosed by the imaginary line and the groove surface is defined as the groove cross-sectional area. The groove width, groove depth, and groove cross-sectional area of ​​the plurality of first circumferential grooves are all the same to each other. The groove width, groove depth, and groove cross-sectional area of ​​the first circumferential groove are the same at any position in the circumferential direction. The angle between the perpendicular line extending from the surface of the first inclined portion (orthogonal to the axis of the split bearing) and the center line of the groove is defined as the groove inclination angle θ2. The center line of the groove on the surface of the first inclined portion is inclined relative to the perpendicular line towards the center line of the first split bearing. The groove inclination angle θ2 in the edge region is smallest at the axial end of the first inclined portion and increases continuously towards the bend. The groove inclination angle θ2 in the central region is smallest at the position adjacent to the center line of the first split bearing and increases continuously towards the bend.

[0016] In another embodiment of the invention, the edge region of the first inclined surface is adjacent to the axial direction end face of the first half-split bearing.

[0017] In another embodiment of the present invention, the axial length W7 is the sum of the axial lengths W5 of the two first inclined surfaces of the first half-split bearing, and the axial length W4 is the sum of the axial lengths W1 of the two second inclined surfaces W2 of the second half-split bearing and the oil groove. The axial length W7 is the same as the axial length W4.

[0018] In another embodiment of the invention, the width W5C of the central region of the first inclined face is more than 25% and less than 75% of the width W5 of the first inclined face.

[0019] In another embodiment of the present invention, the depth D4 of the first inclined face is 0.005 mm or more and 0.050 mm or less.

[0020] In another embodiment of the present invention, the groove depth D5 of the first circumferential groove is 1.5 μm or more and 10 μm or less.

[0021] In another embodiment of the present invention, the groove width W6 of the first circumferential groove is 0.05 mm or more and 0.25 mm or less.

[0022] In another embodiment of the invention, the groove inclination angle θ2 of the first circumferential groove that is closest to the bend of the first inclined surface is greater than the groove inclination angle θ1 of the first circumferential groove that is closest to the centerline of the first half-split bearing by a value in the range of 0.001° to 7°.

[0023] In another embodiment of the present invention, the groove inclination angle θ2 of the first circumferential groove that is closest to the bend of the first inclined surface is greater than the groove inclination angle θ2 of the first circumferential groove that is closest to the axial end of the first inclined surface by a value in the range of 0.001° to 7°. Attached Figure Description

[0024] Figure 1 This is a schematic diagram showing the bearing assembly of the crankshaft. Figure 2 This is a diagram of a sliding bearing of the first specific example of the present invention, viewed from the axial direction of the bearing. Figure 3 Viewed from the sliding surface side Figure 2 Top view of the first half of the split bearing. Figure 4 Viewed from the sliding surface side Figure 2 Top view of the second half of the split bearing. Figure 5 yes Figure 3 AA sectional view. Figure 6 yes Figure 4 BB cross-sectional view. Figure 7 yes Figure 6 Enlarged image. Figure 8A This is an enlarged view of the cross-section of the second circumferential groove (θ1 is close to the minimum). Figure 8B This is an enlarged view of the cross-section of the second circumferential groove (θ1 is close to its maximum). Figure 9A This is a cross-sectional view used to illustrate the function of the present invention. Figure 9B This is a top view used to illustrate the function of the present invention. Figure 10A This is a cross-sectional view used to illustrate the function of the present invention. Figure 9B (CC section view). Figure 10B This is a top view used to illustrate the function of the present invention. Figure 10C It is a component decomposition diagram showing the state where the F1(v) component of oil flow F1 is larger than the F1(h) component. Figure 10D It is a component decomposition diagram showing the state where the F1(h) component of oil flow F1 is larger than the F1(v) component. Figure 11 This is a cross-sectional view of a split bearing, which differs from the specific example. Figure 12 This is a top view of the first half-split bearing of the second embodiment of the present invention, viewed from the sliding surface side. Figure 13 yes Figure 12 DD sectional view. Figure 14 yes Figure 13 Enlarged image. Figure 15A This is an enlarged view of the cross-section of the first circumferential groove (θ2 is close to its minimum). Figure 15B This is an enlarged view of the cross-section of the first circumferential groove (θ2 is close to its maximum). Figure 16A This is a cross-sectional view used to illustrate the function of the present invention. Figure 16B This is a top view used to illustrate the function of the present invention. Figure 17A This is a cross-sectional view used to illustrate the function of the present invention. Figure 16B (EE sectional view). Figure 17B This is a top view used to illustrate the function of the present invention. Figure 17C It is a component decomposition diagram showing the state where the F1(v) component of oil flow F1 is larger than the F1(h) component. Figure 17D It is a component decomposition diagram showing the state where the F1(h) component of oil flow F1 is larger than the F1(v) component. Figure 18 This is a cross-sectional view of a split bearing, which differs from the specific example. Symbol Explanation 1. Bearing assembly; 2-link linkage; 21 large end shell; 22. Large end housing on the side of the rod; 23. Cover side large end shell; 3-link bearing; 31. First half-split bearing; 32. Second half-split bearing; 32a oil tank; The centerline of the axial direction of the 32C oil tank; 32E slot end; 4. Main bearings; 41 First half-split bearing; 42 Second half-split bearing; 42a oil tank; 5 crank pins; 5a Lubrication Circuit; 5b Lubrication circuit; 5c discharge port; 6-axis journal; 6a Lubrication circuit; 6c inlet opening; 7. Sliding surface; 7E axis direction end face; 71. Second tilt of the face; 711 The central region of the second tilted face; 712 The edge region of the second tilted face; 71E The axial end of the second inclined face; 71P The bend of the second tilted face; 71S Second tilted face surface; 72 Second week to the slot; 721 The groove surface of the second circumferential groove; 722 The top of the second circumferential groove; 723 The second week's imaginary straight line towards the groove; 724 The center line of the second circumferential groove; The cross-sectional area of ​​the second circumferential groove in 72A; 73 First tilted face; 731 The central region of the first tilted face; 732 The edge region of the first tilted face; 73E The axial end of the first inclined face; 73P The bend in the first tilted face; The surface of the first tilted face in 73S; 74 First week towards the slot; 741 The groove surface of the first circumferential groove; 742 First circumferential groove top; 743 The first cycle of the imaginary straight line towards the groove; The center line of the first circumferential groove of 744; The cross-sectional area of ​​the first circumferential groove in 74A; 76 circumferential end face; 8-cylinder block; Upper part of the 81 cylinder block; Lower part of the 82-cylinder block; D1 groove depth; D2 Depth of the second tilted face; The groove depth of the second circumferential groove in D3; D4 Depth of the first tilted face; The groove depth of the first circumferential groove of D5; Rcountercurrent; The perpendicular line of the second half-split bearing of VL1; The perpendicular line of the first half-split bearing of VL2; The centerline of the first half-split bearing of WC1 along its axial direction; The centerline of the second half-split bearing of WC2 along its axial direction; W1 slot width; W2 is the length of the second tilted face along its axial direction. axial length of the second central region of W2C; The axial length of the second edge region of W2E; The width of the second circumferential groove in W3; The length of the axis direction of W4 W1+W2×2; W5 is the length of the first tilted face along its axial direction. axial length of the first central region of W5C; The axial length of the first edge region of W5E; The width of the first circumferential groove of W6; The axial length of W7 W5×2; The direction of rotation of the X-axis journal; The direction of rotation of the Z crank pin; θ1 is the inclination angle of the groove in the second circumference. θ2 is the inclination angle of the first circumferential groove. Detailed Implementation

[0025] Hereinafter, a first specific example of the present invention will be described with reference to the accompanying drawings.

[0026] Figure 1 The diagram schematically illustrates a bearing assembly 1 for an internal combustion engine. This bearing assembly 1 includes: a journal 6 supported on the lower part of a cylinder block 8; a crank pin 5 integrally formed with the journal 6 and rotating around the journal 6; and a connecting rod 2 that transmits reciprocating motion from the internal combustion engine to the crank pin 5. Furthermore, the bearing assembly 1 also includes a main bearing 4 and a connecting rod bearing 3 as sliding bearings supporting the crankshaft. The main bearing 4 supports the journal 6 for free rotation, and the connecting rod bearing 3 supports the crank pin 5 for free rotation.

[0027] Furthermore, although the crankshaft has multiple journals 6 and multiple crank pins 5, for ease of explanation, only one journal 6 and one crank pin 5 are illustrated here. Figure 1 In the paper, regarding the positional relationship in the depth direction, the journal 6 is located on the depth side of the paper, and the crank pin 5 is located on the near front side.

[0028] The journal 6 is supported by a main bearing 4, which consists of a pair of split bearings 41 and 42, on the lower part 82 of the internal combustion engine cylinder block. Figure 1 The upper half-split bearing 42 has an oil groove 42a formed along its entire inner circumferential surface. In addition, the journal 6 has a lubrication oil passage 6a that runs through it in the diametrical direction. If the journal 6 rotates in the direction of arrow X, the inlet openings 6c at both ends of the lubrication oil passage 6a alternately communicate with the oil groove 42a of the main bearing 4.

[0029] The crank pin 5 is supported by the connecting rod bearing 3, which consists of a pair of split bearings 31 and 32, on the large end housing 21 of the connecting rod 2 (rod-side large end housing 22 and cover-side large end housing 23).

[0030] As described above, for the main bearing 4, the lubricating oil discharged by the oil pump passes through the oil passage formed in the cylinder wall, through the through-hole formed in the wall of the main bearing 4, and is sent into the oil groove 42a formed on the inner circumferential surface of the main bearing 4.

[0031] Furthermore, a first lubricating oil passage 6a is formed through the journal 6 along its diameter. The inlet opening 6c of the first lubricating oil passage 6a can communicate with the lubricating oil groove 42a. A second lubricating oil passage 5a is formed branching from the first lubricating oil passage 6a through the crank arm (not shown). The second lubricating oil passage 5a communicates with a third lubricating oil passage 5b formed through the journal 6 along its diameter.

[0032] In this way, the lubricating oil passes through the first lubricating oil passage 6a, the second lubricating oil passage 5a and the third lubricating oil passage 5b, and is supplied from the outlet 5c at the end of the third lubricating oil passage 5b to the gap formed between the crank pin 5 and the connecting rod bearing 3.

[0033] First specific example The following describes an example of applying the sliding bearing of the present invention to the connecting rod bearing 3. However, the present invention is not limited to the connecting rod bearing 3, and can also be applied to the main bearing 4.

[0034] Figure 2 This illustrates a first specific example of the sliding bearing (connecting rod bearing 3) of the present invention. The connecting rod bearing 3 is formed by integrally assembling a pair of first half-split bearings 31 and second half-split bearings 32 into a cylindrical shape by mating their circumferential end faces 76. The inner circumferential surface forming the cylindrical shape is the sliding surface 7, and the outer circumferential surface forming the back surface is the back surface.

[0035] Furthermore, the wall thickness of the first half-segment bearing 31 and the second half-segment bearing 32 is constant in the circumferential direction. However, the wall thickness may also be maximum at the circumferential center and continuously decrease toward the two circumferential end faces 76, 76.

[0036] In small internal combustion engines used in passenger cars and commercial vehicles, the outer diameter of the first split bearing 31 and the second split bearing 32 is approximately 30mm to 150mm, the width along the axial direction is approximately 10mm to 50mm, and the wall thickness is approximately 1.5mm to 3mm. In medium-sized internal combustion engines used in industrial applications, the outer diameter is approximately 150mm to 350mm, the width along the axial direction is approximately 50mm to 150mm, and the wall thickness is approximately 3mm to 8mm. These dimensions are just examples; other dimensions can be used.

[0037] Figure 3 This is a view of the first half-split bearing 31 from the sliding surface 7 side. The first half-split bearing 31 has end faces 7E and 7E in the axial direction.

[0038] Figure 5 From Figure 3 The first half-split bearing 31 is viewed in section AA (axial direction section). The sliding surface 7 of the first half-split bearing 31 is parallel to the back surface of the first half-split bearing in the axial direction section.

[0039] Figure 4 This is a view of the second split bearing 32 as seen from the sliding surface 7. The second split bearing 32 has axial end faces 7E, 7E. Furthermore, an oil groove 32a extending circumferentially is formed on the sliding surface 7 of the second split bearing 32, with groove ends 32E, 32E at both ends in the axial direction. The oil groove 32a opens into the two circumferential end faces 76, 76 of the second split bearing 32. Here, a center line WC2 is defined, extending circumferentially through the center of the width of the second split bearing 32 in the axial direction. Similarly, a center line 32C is defined, extending circumferentially through the center of the width of the oil groove 32a in the axial direction. Here, the center line WC2 of the second split bearing 32 coincides with the center line 32C of the oil groove 32a. Alternatively, the oil groove 32a may be formed to open into at least one of the two circumferential end faces 76, 76.

[0040] Figure 6 From Figure 4 A cross-sectional view of the second half-split bearing 32 is shown in section BB (axial direction section). The sliding surface 7 of the second half-split bearing 32 has two adjacent second inclined surfaces 71, 71 along the entire circumferential length of the two ends 32E, 32E of the oil groove 32a. Each of the two second inclined surfaces has a surface 71S, 71S. Each surface 71S, 71S of the second inclined surface is displaced such that it continuously approaches the back surface of the second half-split bearing 32 from the axial direction of each end 71E, 71E of the second inclined surface toward each end 32E, 32E of the oil groove. Here, each axial direction end 71E, 71E of the second inclined surface is adjacent to each axial direction end surface 7E, 7E of the second half-split bearing 32.

[0041] Next, use Figure 7 , Figure 8A and Figure 8B The cross-sectional shape of the second half-split bearing 32 in the axial direction is described in detail.

[0042] Figure 7 yes Figure 6The enlarged view shows the cross-sectional shape of the second half-split bearing 32 in the axial direction. The second inclined surface 71 includes: a central region 711 adjacent to the groove end 32E; and an edge region 712 adjacent to the central region 711 and located further along the axial end face 7E of the second half-split bearing than the central region 711. A bend 71P is present at the boundary between the central region 711 and the edge region 712. Here, the second inclined surface 71, the central region 711, and the edge region 712 have constant axial lengths W2, W2C, and W2E, respectively. Furthermore, the axial length W4 is the sum of the axial lengths W1 of the two second inclined surfaces W2 and W2C of the second half-split bearing 32 and the oil groove 32a.

[0043] Furthermore, the oil groove 32a here has a rectangular cross-section formed by the groove width W1 and the groove depth D1. The groove width W1 is defined as a distance parallel to the back surface of the second half-split bearing 32. Furthermore, the groove depth D1 is defined as the distance from the groove end 32E of the oil groove 32a to the bottom surface of the oil groove 32a in a direction perpendicular to the back surface of the second half-split bearing 32. Here, the groove width W1 is approximately 10% to 30% of the width of the second half-split bearing 32 in the axial direction, and the groove depth D1 is approximately 30% to 70% of the wall thickness of the second half-split bearing 32. These dimensions are just one example; other dimensions can be used.

[0044] The width W2 of the second inclined surface is defined as a distance parallel to the back surface of the second half-segment bearing 32. The width W2 of the second inclined surface is decomposed into the width W2C of the central region and the width W2E of the edge region. Here, the width W2C of the central region is more than 25% and less than 75% of the width W2 of the second inclined surface.

[0045] The central region 711 has a convex curve on the outer diameter side of the second half-split bearing 32. The edge region 712 has a convex curve on the inner diameter side of the second half-split bearing 32. Furthermore, the depth D2 of the second inclined surface is maximum at the adjacent portion adjacent to the groove end 32E of the oil groove, and minimum (zero) at the axial direction end 71E of the second inclined surface. The depth D2 of the second inclined surface is defined as the length from the axial direction end 71E of the second inclined surface to the groove end 32E of the oil groove in a direction perpendicular to the back surface of the second half-split bearing 32. Here, the depth D2 of the second inclined surface is 0.005 mm or more and 0.050 mm or less.

[0046] A plurality of second circumferential grooves 72 are formed adjacent to each other on the surface 71S of the second inclined portion of the second half-split bearing 32. The plurality of second circumferential grooves 72 extend parallel to each other in the circumferential direction and are formed over the entire circumferential length of the surface 71S. Furthermore, the second circumferential grooves 72 are formed over the entire width of the surface 71S. Additionally, the second circumferential grooves 72 are allowed to be slightly inclined (maximum 1°) relative to the circumference of the second half-split bearing 32. For ease of understanding, the second circumferential grooves 72 are depicted exaggeratedly in the accompanying drawings.

[0047] When viewed in cross-section along the axial direction of the second half-split bearing 32, the second circumferential groove 72 has a curved groove surface 721. Tops 722 are formed between the concave surfaces 721 of adjacent second circumferential grooves 72. The curve connecting the tops 722 represents the surface 71S of the second inclined portion. Microscopically, there are no flat areas on the surface 71S of the second inclined portion.

[0048] Figure 8A and Figure 8B express Figure 7 Enlarged view of the second circumferential groove 72. Figure 8A The shape of the second circumferential groove 72 near the groove end 32E of the oil groove in the central region 711 of the second inclined surface 71 and the shape of the second circumferential groove 72 near the axial end 71E of the second inclined surface of the edge region 712 are indicated. Figure 8B This describes the shape of the second circumferential groove 72 near the bend 71P of the central region 711 of the second inclined surface 71 and the shape of the second circumferential groove 72 near the bend 71P of the edge region 712. The groove width W3 of the second circumferential groove 72 is defined as the length of an imaginary straight line 723 connecting the tops 722 of both sides of the second circumferential groove 72. The groove centerline 724 is defined as a line extending through the center of the length of the imaginary straight line 723 in a direction perpendicular to the imaginary straight line 723. The groove depth D3 of the second circumferential groove 72 is defined as the length from the imaginary straight line 723 to the position on the groove surface 721 furthest from the imaginary straight line 723 in a direction perpendicular to the imaginary straight line 723. The maximum groove depth D3 of the second circumferential groove 72 is located on the groove centerline 724. Here, the groove depth D3 of the second circumferential groove 72 is more than 1.5 μm and less than 10 μm. In addition, the groove width W3 of the second circumferential groove 72 is 0.05mm or more and 0.25mm or less.

[0049] The area enclosed by the imaginary straight line 723 and the groove surface 721 is defined as the groove cross-sectional area 72A. The groove width W3, groove depth D3, and groove cross-sectional area 72A of each of the second circumferential grooves 72 are the same. Furthermore, the groove width W3, groove depth D3, and groove cross-sectional area 72A of the second circumferential groove 72 are the same at any position in the circumferential direction.

[0050] Furthermore, the shape of the groove surface 721 of each second circumferential groove 72 is formed symmetrically with respect to the groove centerline 724. The two groove cross-sectional areas obtained by dividing the groove cross-sectional area 72A of each second circumferential groove 72 by the groove centerline 724 are the same.

[0051] The angle between the perpendicular line VL1 extending from the surface 71S of the second inclined portion of the bearing 72 orthogonal to the axis of the second half-split bearing 32 and the center line 724 of the second circumferential groove 72 is defined as the groove inclination angle θ1. The center lines 724 of all the second circumferential grooves 72 in the second inclined portion of the bearing 71 are inclined toward the center line 32C of the oil groove 32a relative to the perpendicular line VL1.

[0052] In the central region 711 of the second inclined surface 71, the second circumferential groove 72 closest to the groove end 32E of the oil groove has the smallest groove inclination angle θ1 (refer to...). Figure 8A The second circumferential groove 72, which is closest to the bend 71P, has the largest groove inclination angle θ1 (refer to...). Figure 8B Therefore, the groove inclination angle θ1 increases continuously from the groove end 32E of the oil groove closer to the bend 71P (towards the outer side in the axial direction). Here, the groove inclination angle θ1 of the second circumferential groove 72 that is closest to the bend 71P of the second inclined surface 71 is greater than the groove inclination angle θ1 of the second circumferential groove that is closest to the groove end 32E by a value in the range of 0.001° to 7°.

[0053] In the edge region 712 of the second inclined surface 71, the second circumferential groove 72 closest to the bend 71P has the largest groove inclination angle θ1 (see reference). Figure 8B The second circumferential groove 72, which is closest to the axial end 71E of the second inclined surface, has the smallest groove inclination angle θ1 (refer to...). Figure 8A Therefore, the groove inclination angle θ1 decreases continuously from the bend 71P closer to the axial end 71E of the second inclined surface (towards the outer side in the axial direction). Here, the groove inclination angle θ1 of the second circumferential groove 72 closest to the bend 71P of the second inclined surface 71 is larger than the groove inclination angle θ1 of the second circumferential groove 72 closest to the axial end 71E of the second inclined surface 71 by a value in the range of 0.001° to 7°.

[0054] In this specific example, the connecting rod bearing 3 is formed by integrally assembling a pair of first half-split bearings 31 and second half-split bearings 32 into a cylindrical shape by mating their circumferential end faces 76. The half-split bearings 31 and 32 can have a sliding layer made of Cu or Al bearing alloy. Alternatively, a sliding layer of Cu or Al bearing alloy can be formed on a back metal layer made of Fe alloy. Furthermore, a sliding layer can be formed by a surface portion composed of Cu or Al bearing alloy and any one of soft Bi, Sn, or Pb, or by an alloy primarily composed of these metals, or by a surface portion composed of a resin composition primarily composed of synthetic resin and disposed closer to the sliding surface than the bearing alloy.

[0055] Next, refer to Figures 9A to 10D The function of the sliding bearing 3 of the present invention will be explained.

[0056] During internal combustion engine operation, due to the explosion pressure within the cylinder and the centrifugal force accompanying the crankshaft rotation, the clearance S between the surface of the crankpin 5 and the sliding surface 7 of the second split bearing 32 constantly changes. Furthermore, lubricating oil existing in the clearance S near the axial center of the sliding surface 7 of the first split bearing 31 flows across the circumferential end face 76 and into the clearance S side near the axial center of the second split bearing 32 as the crankpin 5 rotates. At this time, the lubricating oil passes through the discontinuity formed by the sliding surface 7 of the first split bearing 31 and the oil groove 32a of the second split bearing 32. Therefore, turbulence of lubricating oil is generated in the oil groove 32a near the circumferential end face 76, and cavities 9 are generated in the lubricating oil due to pressure variations.

[0057] Figure 9A This is a cross-sectional view of the connecting rod bearing 3 near the circumferential end face 76. Figure 9B This indicates the view from the sliding surface 7 side. Figure 9A The image. Figure 9A and Figure 9B This indicates that during the operation of the internal combustion engine, the sliding surface 7 of the connecting rod bearing 3 and the surface of the crank pin 5 move relatively closer together from a separated state. When the sliding surface 7 and the surface of the crank pin 5 move relatively closer together from a separated state, the lubricating oil present in the clearance S is pressed towards the sliding surface 7 side. Therefore, the cavity 9 generated in the oil groove 32a moves in a way that it is pressed into the inner side of the oil groove 32a (the outer diameter side of the second half-split bearing 32) along with the lubricating oil.

[0058] Figure 10A yes Figure 9BThe CC section shows the area near the second inclined surface 71. Here, the flow of lubricating oil containing the cavities 9 that move in a manner that is pressed into the oil groove 32a reverses upon reaching the bottom of the oil groove 32a, generating a counterflow R. The reason for this is that the lubricating oil cannot move further towards the outer diameter side of the second half-split bearing 32 than the bottom of the groove. Therefore, the lubricating oil containing the cavities 9 moves in a manner that is pressed out towards the axial end face 7E side of the second half-split bearing 32.

[0059] Furthermore, when the surface of the crankpin 5 approaches the sliding surface 7, the oil flowing circumferentially in the gap S between the surface 71S of the second inclined portion and the surface of the crankpin 5 is pressed by the interior of the multiple second circumferential grooves 72 of the surface 71S of the second inclined portion of the crankpin 5. The oil in each second circumferential groove 72 is squeezed by the oil that flows in after being pressed, and the pressure increases, causing it to flow not only circumferentially in the second circumferential groove 72, but also towards the crankpin 5 side (countercurrent), forming an oil flow F1. Here, the groove centerline 724 of each second circumferential groove 72 of the surface 71S of the second inclined portion is inclined towards the centerline 32C of the oil groove 32a. Therefore, the oil flow F1 flowing out of the second circumferential groove 72 mainly flows obliquely towards the surface side of the crankpin 5 and the centerline 32C of the oil groove 32a. In addition, at this time, the oil flow F2 (refer to) flowing circumferentially in the gap S between the surface 71S of the second inclined portion and the surface of the crankpin 5 attached to the rotating crankpin 5 (refer to the gap S between the surface 71S of the second inclined portion and the surface of the crankpin 5) flows circumferentially. Figure 10B . Figure 10B Viewed from the sliding surface 7 side of the second half-split bearing 32 Figure 10A (Image).

[0060] The cavity 9, extruded by the counter-current R, is conveyed along with the lubricating oil through oil flows F1 and F2 within the gap S towards the front side of the crank pin's rotational direction Z. Since the central region 711 of the second inclined surface 71 where the cavity 9 exists has a convex curve protruding towards the outer diameter side of the second half-split bearing 32, the oil flow F1 has the following components.

[0061] like Figure 10C and Figure 10D As shown, the oil flow F1 decomposes into a component F1(v) towards the surface side of the crank pin 5 and a component F1(h) towards the centerline 32C side of the oil groove 32a. In the central region 711, as... Figure 10C As shown, the F1(v) of the oil flow F1 flowing out from the second circumferential groove 72 near the groove end 32E of the oil groove of the second inclined surface 71 becomes relatively larger.

[0062] On the other hand, in the central region at location 711, such as Figure 10D As shown, the F1(h) of the oil flow F1 flowing out from the second circumferential groove 72 near the bend 71P of the second inclined surface 71 becomes relatively larger.

[0063] In the central region 711, the flow component of the oil flow F1, which flows out from the second circumferential groove 72 between the groove end 32E and the bend 71P, flows from the groove end 32E toward the bend 71P (towards the outer side of the axial direction of the second half-split bearing 32). Figure 10C The flow components shown change continuously as follows: Figure 10D The flow components are shown. According to this structure, the oil flow F1 in the central region 711 of the second inclined surface 71 presses the lubricating oil present in the central region 711 together with the cavities 9 toward the centerline 32C side of the oil groove 32a and toward the surface of the crank pin 5. As the pressure of the lubricating oil in the pressed central region 711 increases, the cavities 9 contained in the lubricating oil collapse rapidly within the central region 711 due to the pressure. Therefore, it is possible to prevent the cavities 9 from flowing into the edge region 712 of the second inclined surface 71. Therefore, it is possible to prevent the cavities 9 from collapsing near the surface 71S of the edge region 712 where the gap S narrows, thus preventing cavitation on the surface 71S of the edge region 712. In addition, at this time, the cavities 9 in the central region 711 are pushed upward toward the surface of the crank pin 5 together with the lubricating oil, and away from the surface 71S of the central region 711. In addition, the depth D2 of the second inclined surface is the deepest on the side of the centerline 32C of the oil groove 32a where the cavities 9 are pressed and moved. Therefore, it is possible to prevent cavitation from occurring on the surface 71S of the central region 711 and the groove surface 721 when the cavity 9 collapses in the central region 711.

[0064] Furthermore, since the edge region 712 of the second inclined surface 71 has a convex curve protruding toward the inner diameter side of the second half-split bearing 32, the oil flow F1 has the following components.

[0065] In edge region 712, such as Figure 10D As shown, the F1(h) of the oil flow F1 flowing out from the second circumferential groove 72 near the bend 71P of the second inclined surface 71 becomes relatively larger.

[0066] On the other hand, in the edge region 712, such as Figure 10C As shown, the F1(v) of the oil flow F1 flowing out from the second circumferential groove 72 near the axial end 71E of the second inclined surface becomes relatively larger.

[0067] Therefore, even assuming that not all cavities 9 in the central region 711 break down within the central region 711 and some flow into the edge region 712, near the bend 71P of the edge region 712, the cavities 9, along with the lubricating oil, are pressed towards the centerline 32C of the oil groove 32a. This has the effect of pressing the cavities 9 flowing into the edge region 712 back into the central region 711. Furthermore, even assuming that the cavities 9 reach near the axial end 71E of the edge region 712, near the axial end 71E of the edge region 712, the cavities 9, along with the lubricating oil, are pressed towards the surface of the crank pin 5. Therefore, within the gap S away from the surface 71S of the edge region 712, the cavities 9 can be broken down by repeated pressure, thereby preventing cavitation on the surface 71S of the edge region 712 and the groove surface 721.

[0068] The width W2C of the central region of the second inclined surface is preferably 25% to 75% of the width W2 of the second inclined surface. When the width W2C of the central region is less than 25% of the width W2 of the second inclined surface, the cavity 9 is less likely to be pressed against the surface of the crank pin 5 along with the lubricating oil near the groove end 32E of the oil groove 32. Therefore, the cavity 9 is prone to breakage within the gap S of the surface 71S near the central region 711, and cavitation is likely to occur on the surface 71S of the central region 711 and the groove surface 721 near the groove end 32E. When the width W2C of the central region exceeds 75% of the width W2 of the second inclined surface, the cavity 9 is less likely to be pressed against the surface of the crank pin 5 along with the lubricating oil near the axial end 71E of the second inclined surface. Therefore, the cavity 9 is prone to breakage within the gap S of the surface 71S near the edge region 712, and cavitation is likely to occur on the surface 71S of the edge region 712 and the groove surface 721 near the axial end 71E.

[0069] The depth D2 of the second inclined surface is preferably 0.005 mm or more and 0.050 mm or less. When the depth D2 of the second inclined surface is less than 0.005 mm, even if the cavity 9 is pressed by the oil flow F1, the gap S between the surface 71S of the second inclined surface and the surface of the crank pin 5 will narrow, making the cavity 9 prone to breakage near the surface 71S of the second inclined surface, and cavitation is likely to occur at that location. When the depth D2 of the second inclined surface exceeds 0.050 mm, oil film rupture is likely to occur in the second inclined surface, and sintering is likely to occur.

[0070] The groove depth D3 of the second circumferential groove 72 is 1.5 μm or more and 10 μm or less. Furthermore, the groove width W3 of the second circumferential groove 72 is preferably 0.05 mm or more and 0.25 mm or less. When the groove depth D3 of the second circumferential groove 72 exceeds 10 μm or the groove width W3 exceeds 0.25 mm, the oil flow F1 weakens. Additionally, when the groove depth D3 of the second circumferential groove 72 is less than 1.5 μm or the groove width W3 is less than 0.05 mm, the amount of oil flow F1 flowing from the gap S between the surface 71S of each second circumferential groove 72 toward the surface of the second inclined face and the surface of the crank pin 5 decreases. Therefore, the cavity 9 may not be sufficiently pressed.

[0071] Preferably, the groove inclination angle θ1 of the second circumferential groove 72 closest to the bend 71P of the second inclined surface 71 is greater than the groove inclination angle θ1 of the second circumferential groove 72 closest to the groove end 32E by a value within the range of 0.001° to 7°. When the groove inclination angle θ1 of the second circumferential groove 72 closest to the bend 71P is less than 0.001° greater than the groove inclination angle θ1 of the second circumferential groove 72 closest to the groove end 32E, the F1(h) component of the oil flow F1 exiting from the second circumferential groove 72 in the central region 711 becomes too small. Therefore, the cavity 9 is not easily pressed towards the centerline 32C side of the oil groove 32a, and the cavity 9 easily flows out towards the edge region 712. Furthermore, when the groove inclination angle θ1 of the second circumferential groove 72 closest to the bend 71P is more than 7° greater than the groove inclination angle θ1 of the second circumferential groove 72 closest to the groove end 32E, the F1(v) component of the oil flow F1 flowing out from the second circumferential groove 72 in the central region 711 becomes too small. Therefore, the cavity 9 is not easily pressed against the surface side facing the crank pin 5, and the cavity 9 is prone to breakage near the surface 71S of the central region 711 and the groove surface 721.

[0072] Preferably, the groove inclination angle θ1 of the second circumferential groove 72 closest to the bend 71P of the second inclined surface 71 is greater than the groove inclination angle θ1 of the second circumferential groove 72 closest to the axial end 71E of the second inclined surface 71 by a value within the range of 0.001° to 7°. When the groove inclination angle θ1 of the second circumferential groove 72 closest to the bend 71P is less than 0.001° greater than the groove inclination angle θ1 of the second circumferential groove 72 closest to the axial end 71E of the second inclined surface 71, the F1(h) component of the oil flow F1 flowing from the second circumferential groove 72 near the bend 71P of the edge region 712 becomes too small. Therefore, it is difficult to force the cavity 9 into the central region 711, and the cavity 9 is prone to collapse within the edge region 712. Furthermore, when the groove inclination angle θ1 of the second circumferential groove 72 closest to the bend 71P is more than 7° greater than the groove inclination angle θ1 of the second circumferential groove 72 closest to the axial end 71E of the second inclined surface 71, the cavity 9 is less likely to be pushed upward toward the surface side of the crank pin 5. Therefore, the cavity 9 is prone to breakage near the surface 71S of the edge region 712 and the groove surface 721.

[0073] At any circumferential position, the groove depth D3, groove width W3, and groove cross-sectional area 72A of each of the second circumferential grooves 72 formed on the second inclined surface 71 are the same. By making the groove depth D3, groove width W3, and groove cross-sectional area 72A of each of the second circumferential grooves 72 of the second inclined surface 71 the same, when the internal combustion engine is running, the pressure of the oil pressed and flowing into each of the second circumferential grooves 72 increases approximately simultaneously when the surface of the crankpin 5 approaches the sliding surface 7, and the oil flow F1 flowing backward from each of the second circumferential grooves 72 toward the gap S between the surface 71S of the second inclined surface 71 and the surface of the crankpin 5 is formed approximately simultaneously. Therefore, since the cavity 9 is pressed non-obliquely toward the centerline 32C side of the oil groove 32a, it is easy for the cavity 9 to stably break on the surface side of the crankpin 5 near the centerline 32C of the oil groove 32a.

[0074] Furthermore, during internal combustion engine operation, when the surfaces of the sliding surface 7 and the crankpin 5 change from a close state to a separated state, the cavities 9 existing in the gap S move along with the lubricating oil in a direction away from the sliding surface 7 (towards the surface of the crankpin 5). Additionally, since the gap S is also widened, the cavities 9 in the central region 711 or the edge region 712 break down at a sufficiently far distance from the surface 71S and groove surface 721 of the second inclined surface, preventing cavitation from occurring in the surface 71S and groove surface 721 of the second inclined surface.

[0075] Unlike the structure of this specific example, when the center line 724 of the second circumferential groove 72 is not inclined toward the center line 32C of the oil groove 32a relative to the vertical line VL1, but is inclined toward the end face 7E of the second half-split bearing in the axial direction, when the surface of the crank pin 5 is close to the sliding surface 7, although it has the effect of pushing the lubricating oil and the cavity 9 upward toward the surface of the crank pin 5, the cavity 9 tends to flow into the edge region 712 because the lubricating oil and the cavity 9 have a pressing flow toward the outer side in the axial direction.

[0076] Figure 11 This is a cross-sectional view of a split bearing, which has a structure different from that of this specific example. Figure 11 In this case, the surface 71S of the second inclined portion does not have a bend 71P, but is formed only by a convex curve protruding outwards. Furthermore, no second circumferential groove 72 is formed on the surface 71S of the second inclined portion. In this situation, no oil flow F1 is generated in the lubricating oil in the gap S between the surface 71S of the second inclined portion and the surface of the crank pin 5, moving towards the centerline 32C of the oil groove 32a. Therefore, the lubricating oil containing the cavities 9 forced out by the counterflow R easily diffuses outwards in the axial direction of the second split bearing 32, and the cavities 9 easily reach the vicinity of the axial end 71E of the second inclined portion. Therefore, cavitation easily occurs on the surface 71S near the axial end 71E.

[0077] Furthermore, unlike the structure of this specific example, when the groove depth D3, groove width W3, and groove cross-sectional area 72A of each of the second circumferential grooves 72 on the second inclined surface 71 are not constant, the pressure of the oil pressed and flowing into each of the second circumferential grooves 72 will not be the same simultaneously when the surface of the crank pin 5 is close to the sliding surface 7. Therefore, the oil flow F1 flowing backward from each of the second circumferential grooves 72 towards the gap S between the surface 71S of the second inclined surface 71 and the surface of the crank pin 5 will not form approximately simultaneously. Alternatively, the second circumferential groove 72 with a relatively large groove depth D3, groove width W3, and groove cross-sectional area 72A will not form an oil flow F1 (oil flows circumferentially within the second circumferential groove 72) due to the low pressure of the flowing oil. Therefore, the cavity 9 is not easily and stably pressed against the surface side of the crank pin 5 near the centerline 32C of the oil groove 32a, and cavitation may sometimes occur on the surface 71S and the groove surface 721.

[0078] Second specific example Next, a second specific example of the present invention will be described. Furthermore, the second specific example has the same structure as the first specific example, except for the structure of the first half-split bearing 31 described below.

[0079] Figure 12This is a view of the first half-split bearing 31 in the second specific example, viewed from the sliding surface 7 side. The first half-split bearing 31 has axial direction end faces 7E, 7E. Here, a center line WC1 is defined that passes through the center of the width of the first half-split bearing 31 in the axial direction and extends circumferentially.

[0080] Figure 13 From Figure 12 A cross-sectional view of the first split bearing 31 is observed from the DD section (axial direction section). The sliding surface 7 of the first split bearing 31 has two first inclined surfaces 73, 73 adjacent to the centerline WC1 of the first split bearing. The two first inclined surfaces have surfaces 73S, 73S. The surfaces 73S, 73S of the first inclined surfaces are displaced in a manner that they continuously approach the back surface of the first split bearing 31 from the axial direction of each end 73E, 73E side toward the centerline WC1 of the first split bearing.

[0081] Next, use Figure 14 , Figure 15A and Figure 15B The cross-sectional shape of the first half-split bearing 31 in the axial direction is described in detail.

[0082] Figure 14 yes Figure 13 The enlarged view shows the cross-sectional shape of the first half-split bearing 31 in the axial direction. The first inclined surface 73 includes: a central region 731 adjacent to the centerline WC1 of the first half-split bearing; and an edge region 732 adjacent to the central region 731 and located further along the axial end face 7E of the first half-split bearing than the central region 731. A bend 73P is present at the boundary between the central region 731 and the edge region 732. Here, the first inclined surface 73, the central region 731, and the edge region 732 have constant axial lengths W5, W5C, and W5E, respectively. Furthermore, the combined axial lengths W5 of the two first inclined surfaces 73, 73 of the first half-split bearing 31 are W7.

[0083] The width W5 of the first inclined surface is defined as a distance parallel to the back surface of the first half-split bearing 31. The width W5 of the first inclined surface is decomposed into the width W5C of the central region and the width W5E of the edge region. Here, the width W5C of the central region is more than 25% and less than 75% of the width W5 of the first inclined surface.

[0084] The central region 731 has a convex curve protruding towards the outer diameter side of the first half-split bearing 31. The edge region 732 has a convex curve protruding towards the inner diameter side of the first half-split bearing 31. Furthermore, the depth D4 of the first inclined surface is maximum at the adjacent portion adjacent to the centerline WC1 of the first half-split bearing, and minimum (zero) at the axial end 73E of the first inclined surface (in...). Figure 14 (This is not the case in the illustration). Furthermore, the depth D4 of the first inclined surface is defined as the length from the axial end 73E of the first inclined surface to the intersection of the centerline WC1 of the first half-split bearing and the surface 73S in a direction perpendicular to the back surface of the first half-split bearing 31. Here, the depth D4 of the first inclined surface is 0.005 mm or more and 0.050 mm or less.

[0085] A plurality of first circumferential grooves 74 are formed adjacent to each other on the surface 73S of the first inclined portion of the first half-split bearing 31. The plurality of first circumferential grooves 74 extend parallel to each other in the circumferential direction and are formed throughout the entire circumferential length of the surface 71S. Furthermore, the first circumferential grooves 74 are formed throughout the entire width of the surface 71S. Additionally, the first circumferential grooves 74 are allowed to be slightly inclined (maximum 1°) relative to the circumference of the first half-split bearing 31. For ease of understanding, the first circumferential grooves 74 are depicted in an exaggerated manner in the accompanying drawings.

[0086] When viewed in cross-section along the axial direction of the first split bearing 31, the first circumferential groove 74 has a curved groove surface 741. Tops 742 are formed between the concave surfaces 741 of adjacent first circumferential grooves 74. The curve connecting the tops 742 represents the surface 73S of the first inclined portion. Microscopically, there are no flat areas on the surface 73S of the first inclined portion.

[0087] Figure 15A and 15B express Figure 14 Enlarged view of the first circumference of groove 74. Figure 15A This indicates the shape of the first circumferential groove 74 near the center line WC1 of the first half-split bearing in the central region 731 of the first inclined face 73 and the shape of the first circumferential groove 74 near the axial end 73E of the first inclined face in the edge region 732. Figure 15BThis describes the shape of the first circumferential groove 74 near the bend 73P of the central region 731 of the first inclined surface 73 and the shape of the first circumferential groove 74 near the bend 73P of the edge region 732. The groove width W6 of the first circumferential groove 74 is defined as the length of an imaginary straight line 743 connecting the tops 742 of both sides of the first circumferential groove 74. The groove centerline 744 is defined as a line extending through the center of the length of the imaginary straight line 743 in a direction perpendicular to the imaginary straight line 743. The groove depth D5 of the first circumferential groove 74 is defined as the length from the imaginary straight line 743 to the position on the groove surface 741 furthest from the imaginary straight line 743 in a direction perpendicular to the imaginary straight line 743. The maximum groove depth D5 of the first circumferential groove 74 is located on the groove centerline 744. Here, the groove depth D5 of the first circumferential groove 74 is more than 1.5 μm and less than 10 μm. In addition, the groove width W6 of the first circumferential groove 74 is 0.05mm or more and 0.25mm or less.

[0088] The area enclosed by the imaginary straight line 743 and the groove surface 741 is defined as the groove cross-sectional area 74A. The groove width W6, groove depth D5, and groove cross-sectional area 74A of each of the first circumferential grooves 74 are the same. Furthermore, the groove width W6, groove depth D5, and groove cross-sectional area 74A of the first circumferential groove 74 are the same at any position in the circumferential direction.

[0089] Furthermore, the shape of the groove surface 741 of each first circumferential groove 74 is formed symmetrically with respect to the groove centerline 744. The two groove cross-sectional areas obtained by dividing the groove cross-sectional area 74A of each first circumferential groove 74 by the groove centerline 744 are the same.

[0090] The angle between the perpendicular line VL2 extending from the surface 73S of the first inclined portion of the bearing, orthogonal to the axis of the first half-split bearing 31, and the center line 744 of the first circumferential groove 74 is defined as the groove inclination angle θ2. The center lines 744 of all the first circumferential grooves 74 in the first inclined portion of the bearing 73 are inclined relative to the perpendicular line VL2 toward the center line WC1 of the first half-split bearing.

[0091] In the central region 731 of the first inclined surface 73, the first circumferential groove 74, which is closest to the centerline WC1 of the first half-split bearing, has the smallest groove inclination angle θ2 (refer to...). Figure 15A The first circumferential groove 74, which is closest to the bend 73P, has the largest groove inclination angle θ2 (refer to...). Figure 15BTherefore, the groove inclination angle θ2 increases continuously from the centerline WC1 of the first half-split bearing closer to the bend 73P (towards the outer side in the axial direction). Here, the groove inclination angle θ2 of the first circumferential groove 74 closest to the bend 73P of the first inclined surface 73 is larger than the groove inclination angle θ2 of the first circumferential groove closest to the centerline WC1 of the first half-split bearing by a value in the range of 0.001° to 7°.

[0092] In the edge region 732 of the first inclined surface 73, the first circumferential groove 74, which is closest to the bend 73P, has the largest groove inclination angle θ2 (refer to...). Figure 15B The first circumferential groove 74, which is closest to the axial end 73E of the first inclined surface, has the smallest groove inclination angle θ2 (refer to...). Figure 15A Therefore, the groove tilt angle θ2 decreases continuously from the bend 73P closer to the axial end 73E of the first inclined surface (towards the outer side of the axial direction). Here, the groove tilt angle θ2 of the first circumferential groove 74 closest to the bend 73P of the first inclined surface 73 is greater than the groove tilt angle θ2 of the first circumferential groove 74 closest to the axial end 73E of the first inclined surface 73 by a value in the range of 0.001° to 7°.

[0093] Furthermore, here, the axial length W7, which is the sum of the axial lengths W5, W5 of the two first inclined surfaces 73, 73 of the first half-split bearing 31, is the same as the axial length W4, which is the sum of the axial lengths W1 of the two second inclined surfaces W2, W2 of the second half-split bearing 32 and the oil groove 32a.

[0094] Next, refer to Figures 16A to 17D The function of the sliding bearing 3 of the present invention will be explained.

[0095] When the internal combustion engine is running, the lubricating oil in the oil groove 32a of the second half-split bearing 32 crosses the circumferential end face 76 and flows into the gap S near the center line WC1 of the first half-split bearing 31. If the lubricating oil in the oil groove 32a contains cavities 9, the cavities 9 flow into the gap S near the center line WC1 of the first half-split bearing 31 together with the flow of lubricating oil.

[0096] Figure 16A This is a cross-sectional view of the connecting rod bearing 3 near the circumferential end face 76. Figure 16B This indicates the view from the sliding surface 7 side. Figure 16A The image. Figure 16A and Figure 16BThis indicates the state in which the sliding surface 7 of the connecting rod bearing 3 and the surface of the crank pin 5 move relatively closer together from a separated state during the operation of the internal combustion engine. When the sliding surface 7 and the surface of the crank pin 5 move relatively closer together from a separated state, the lubricating oil present in the gap S is pressed towards the sliding surface 7. Therefore, the cavity 9 in the gap S near the centerline WC1 of the first half-split bearing 31 moves in a way that it is pressed into the sliding surface 7 of the first half-split bearing 31 along with the lubricating oil.

[0097] Figure 17A yes Figure 16B The EE section shows the area near the first inclined surface 73. When the surface of the crank pin 5 approaches the sliding surface 7, the oil flowing circumferentially in the gap S between the surface 73S of the first inclined surface and the surface of the crank pin 5 is pressed against the interior of a plurality of first circumferential grooves 74 of the surface of the crank pin 5 facing the surface 73S of the first inclined surface. The oil in each first circumferential groove 74 is compressed by the oil that subsequently flows in through the pressing, increasing its pressure. This causes the oil to flow not only circumferentially within the first circumferential groove 74 but also towards the crank pin 5 side (countercurrent flow), forming an oil flow F1. Here, the groove centerline 744 of each first circumferential groove 74 of the surface 73S of the first inclined surface is inclined towards the centerline WC1 of the first half-split bearing. Therefore, the oil flow F1 flowing out of the first circumferential groove 74 flows primarily towards the surface side of the crank pin 5 and the centerline WC1 side of the first half-split bearing. Additionally, at this time, an oil flow F2 (refer to) flows circumferentially in the gap S between the surface 73S of the first inclined portion and the surface of the crank pin 5, which is formed by the rotation of the crank pin 5. Figure 17B . Figure 17B Viewed from the sliding surface 7 side of the first half-split bearing 31 Figure 17A (Image).

[0098] Here, a central region 731 of the first inclined surface is formed near the centerline WC1 of the first split bearing 31. Therefore, the oil groove 32a of the second split bearing 32 flows into the cavity 9 of the gap S near the centerline WC1 of the first split bearing 31, and together with the lubricating oil, is transported within the gap S towards the front side of the crankpin's rotational direction Z via oil flows F1 and F2. Since the central region 731 of the first inclined surface 73 has a convex curve protruding towards the outer diameter side of the first split bearing 31, the oil flow F1 has the following components.

[0099] like Figure 17C and Figure 17D As shown, the oil flow F1 is decomposed into a component F1(v) toward the surface side of the crank pin 5 and a component F1(h) toward the centerline WC1 side of the first half-split bearing 31. In the central region 731, as... Figure 17CAs shown, the F1(v) of the oil flow F1 flowing out from the first circumferential groove 74 near the center line WC1 of the first half-split bearing 31 becomes relatively larger.

[0100] On the other hand, in the central region 731, such as Figure 17D As shown, the F1(h) of the oil flow F1 flowing out from the first circumferential groove 74 near the bend 73P of the first inclined surface 73 becomes relatively larger.

[0101] In the central region 731, the flow component of the oil flow F1, which flows out from the first circumferential groove 74 between the centerline WC1 of the first half-split bearing 31 and the bend 73P, flows from the centerline WC1 of the first half-split bearing 31 toward the bend 73P (towards the outer side of the axial direction of the first half-split bearing 31). Figure 17C The flow components shown change continuously as follows: Figure 17D The flow components are shown. According to this structure, the oil flow F1 in the central region 731 of the first inclined surface 73 presses the lubricating oil present in the central region 731 together with the cavity 9 toward the centerline WC1 side of the first half-split bearing 31 and toward the surface of the crank pin 5. As the pressure of the lubricating oil in the pressed central region 731 increases, the cavity 9 contained in the lubricating oil collapses rapidly within the central region 731 due to the pressure. Therefore, it is possible to prevent the cavity 9 from flowing into the edge region 732 of the first inclined surface 73. Therefore, it is possible to prevent the cavity 9 from collapsing near the surface 73S of the edge region 732 where the gap S narrows and causing cavitation on the surface 73S of the edge region 732. In addition, at this time, the cavity 9 in the central region 731 is pushed upward along with the lubricating oil to the vicinity of the surface of the crank pin 5 and leaves from the surface 73S of the central region 731. In addition, the depth D4 of the first inclined surface is deepest on the centerline WC1 side of the first half-split bearing 31 where the cavity 9 is pressed and moved. Therefore, it is possible to prevent cavitation from occurring on the surface 73S of the central region 731 and the groove surface 741 when the cavity 9 collapses in the central region 731.

[0102] In addition, since the edge region 732 of the first inclined surface 73 has a convex curve protruding toward the inner diameter side of the first half-split bearing 31, the oil flow F1 has the following components.

[0103] In edge region 732, such as Figure 17D As shown, the F1(h) of the oil flow F1 flowing out from the first circumferential groove 74 near the bend 73P of the first inclined surface 73 becomes relatively larger.

[0104] On the other hand, in the edge region 732, such as Figure 17C As shown, the F1(v) of the oil flow F1 flowing out from the first circumferential groove 74 near the axial end 73E of the first inclined surface becomes relatively larger.

[0105] Therefore, even assuming that not all cavities 9 in the central region 731 break down within the central region 731 and some flow into the edge region 732, near the bend 73P of the edge region 732, the cavities 9, along with the lubricating oil, are pressed towards the centerline WC1 side of the first half-split bearing 31. This has the effect of pressing the cavities 9 flowing into the edge region 732 into the central region 731. Furthermore, even assuming that the cavities 9 reach near the axial end 73E of the edge region 732, near the axial end 73E of the edge region 732, the cavities 9, along with the lubricating oil, are pressed towards the surface side of the crank pin 5. Therefore, within the gap S away from the surface 73S of the edge region 732, the cavities 9 can be broken down by repeated pressure, thereby preventing cavitation on the surface 73S of the edge region 732 and the groove surface 741.

[0106] The width W5C of the central region of the first inclined surface is preferably 25% to 75% of the width W5 of the first inclined surface. When the width W5C of the central region is less than 25% of the width W5 of the first inclined surface, near the centerline WC1 of the first split bearing, the cavity 9 is less likely to be pressed against the surface of the crank pin 5 along with the lubricating oil. Therefore, the cavity 9 is prone to breakage within the gap S of the surface 73S near the central region 731, and cavitation is likely to occur on the surface 73S of the central region 731 and the groove surface 741 near the centerline WC1 of the first split bearing. When the width W5C of the central region exceeds 75% of the width W5 of the first inclined surface, near the axial end 73E of the first inclined surface, the cavity 9 is less likely to be pressed against the surface of the crank pin 5 along with the lubricating oil. Therefore, the cavity 9 is prone to breakage within the gap S of the surface 73S near the edge region 732, and cavitation is likely to occur on the surface 73S of the edge region 732 and the groove surface 741 near the axial end 73E.

[0107] The depth D4 of the first inclined surface is preferably 0.005 mm or more and 0.050 mm or less. When the depth D4 of the first inclined surface is less than 0.005 mm, even if the cavity 9 is pressed by the oil flow F1, the gap S between the surface 73S of the first inclined surface and the surface of the crank pin 5 will narrow, making the cavity 9 prone to breakage near the surface 73S of the first inclined surface, and cavitation is likely to occur at that location. When the depth D4 of the first inclined surface exceeds 0.050 mm, oil film rupture is likely to occur in the first inclined surface, and sintering is likely to occur.

[0108] The groove depth D5 of the first circumferential groove 74 is 1.5 μm or more and 10 μm or less. Furthermore, the groove width W6 of the first circumferential groove 74 is preferably 0.05 mm or more and 0.25 mm or less. When the groove depth D5 of the first circumferential groove 74 exceeds 10 μm or the groove width W6 exceeds 0.25 mm, the oil flow F1 weakens. Additionally, when the groove depth D5 of the first circumferential groove 74 is less than 1.5 μm or the groove width W6 is less than 0.05 mm, the amount of oil flow F1 flowing from the surface 73S of each first circumferential groove 74 towards the gap S between the surface of the first inclined face and the surface of the crank pin 5 decreases. Therefore, the cavity 9 may not be sufficiently pressed.

[0109] Preferably, the groove inclination angle θ2 of the first circumferential groove 74 closest to the bend 73P of the first inclined surface 73 is greater than the groove inclination angle θ2 of the first circumferential groove 74 closest to the centerline WC1 of the first half-split bearing 31 by a value within the range of 0.001° to 7°. When the groove inclination angle θ2 of the first circumferential groove 74 closest to the bend 71P is less than 0.001° greater than the groove inclination angle θ2 of the first circumferential groove 74 closest to the centerline WC1 of the first half-split bearing 31, the F1(h) component of the oil flow F1 flowing out from the first circumferential groove 74 in the central region 731 becomes too small. Therefore, the cavity 9 is not easily pressed towards the centerline WC1 side of the first half-split bearing 31, and the cavity 9 easily flows out towards the edge region 732. Furthermore, when the groove inclination angle θ2 of the first circumferential groove 74 closest to the bend 73P is more than 7° greater than the groove inclination angle θ2 of the first circumferential groove 74 closest to the centerline WC1 of the first half-split bearing 31, the F1(v) component of the oil flow F1 flowing out from the first circumferential groove 74 in the central region 731 becomes too small. Therefore, the cavity 9 is not easily pressed against the surface side facing the crank pin 5, and the cavity 9 is prone to breakage near the surface 73S of the central region 731 and the groove surface 741.

[0110] Preferably, the groove inclination angle θ2 of the first circumferential groove 74 closest to the bend 73P of the first inclined surface 73 is greater than the groove inclination angle θ2 of the first circumferential groove 74 closest to the axial end 73E of the first inclined surface 73 by a value within the range of 0.001° to 7°. When the groove inclination angle θ2 of the first circumferential groove 74 closest to the bend 73P is less than 0.001° greater than the groove inclination angle θ2 of the first circumferential groove 74 closest to the axial end 73E of the first inclined surface 73, the F1(h) component of the oil flow F1 flowing from the first circumferential groove 74 near the bend 73P in the edge region 732 becomes too small. Therefore, it is difficult to force the cavity 9 into the central region 731, and the cavity 9 is prone to collapse within the edge region 732. Furthermore, when the groove inclination angle θ2 of the first circumferential groove 74 closest to the bend 73P is more than 7° greater than the groove inclination angle θ2 of the first circumferential groove 74 closest to the axial end 73E of the first inclined surface 73, the cavity 9 is less likely to be pushed upward toward the surface side of the crank pin 5. Therefore, the cavity 9 is prone to breakage near the surface 73S of the edge region 732 and the groove surface 741.

[0111] At any circumferential position, the groove depth D5, groove width W6, and groove cross-sectional area 74 of each of the first circumferential grooves 74 formed on the first inclined surface 73 are identical. By making the groove depth D5, groove width W6, and groove cross-sectional area 74A of each of the first circumferential grooves 74 of the first inclined surface 73 identical, when the internal combustion engine is running and the surface of the crankpin 5 approaches the sliding surface 7, the pressure of the oil pressed and flowing into each of the first circumferential grooves 74 increases almost simultaneously and equally, and the oil flow F1 flowing backward from each of the first circumferential grooves 74 to the gap S between the surface 73S of the first inclined surface 73 and the surface of the crankpin 5 is formed almost simultaneously. Therefore, since the cavity 9 presses against the centerline WC1 side of the first half-split bearing 31 without bias, it is easy for the cavity 9 to stably break on the surface side of the crankpin 5 near the centerline WC1 of the first half-split bearing 31.

[0112] Furthermore, in this specific example, the axial length W7, resulting from the sum of the axial lengths W5, W5 of the two first inclined surfaces 73, 73 of the first half-split bearing 31, is made the same as the axial length W4, resulting from the sum of the axial lengths W1 of the two second inclined surfaces W2, W2 of the second half-split bearing 32 and the oil groove 32a. Therefore, the following effect is achieved: when the lubricating oil in the gap S between the sliding surface 7 and the crank pin 5 of the first half-split bearing 31 crosses the circumferential end face 76 and flows into the gap S between the sliding surface 7 and the crank pin 5 of the second half-split bearing 32 (or conversely, when the lubricating oil in the gap S between the sliding surface 7 and the crank pin 5 of the second half-split bearing 32 crosses the circumferential end face 76 and flows into the gap S between the sliding surface 7 and the crank pin 5 of the first half-split bearing 31), oil flows F1 and F2 of the same degree are formed in the first half-split bearing 31 and the second half-split bearing 32. Therefore, the lubricating oil flows stably, which can prevent the turbulence of the lubricating oil when passing the circumferential end face 76, and can effectively prevent the formation of cavitation 9 when passing the circumferential end face 76.

[0113] Furthermore, during internal combustion engine operation, when the surfaces of the sliding surface 7 and the crankpin 5 change from a close state to a separated state, the cavities 9 existing in the gap S, along with the lubricating oil, follow the surface of the crankpin 5 and move in a direction away from the sliding surface 7 (the surface side of the crankpin 5). Additionally, since the gap S is also widened, the cavities 9 in the central region 731 or the edge region 732 break down at a position sufficiently far from the surface 73S of the first inclined face and the groove surface 741, thereby preventing cavitation in the surface 73S of the first inclined face and the groove surface 741.

[0114] Unlike the structure of this specific example, when the center line 744 of the first circumferential groove 74 is not inclined toward the center line WC1 of the first half-split bearing 31 relative to the vertical line VL2, but is inclined toward the end face 7E of the first half-split bearing in the axial direction, when the surface of the crank pin 5 is close to the sliding surface 7, although it has the effect of pushing the lubricating oil and the cavity 9 upward toward the surface side of the crank pin 5, the cavity 9 easily flows into the edge region 732 because the lubricating oil and the cavity 9 have a pressing flow toward the outer side in the axial direction.

[0115] Figure 18 This is a cross-sectional view of a split bearing, which has a structure different from that of this specific example. Figure 18In this case, the surface 73S of the first inclined portion does not have a bend 73P, but is formed only by a convex curve protruding outwards. Furthermore, no first circumferential groove 74 is formed on the surface 73S of the first inclined portion. In this situation, no oil flow F1 towards the centerline WC1 side of the first split bearing 31 is generated in the lubricating oil in the gap S between the surface 73S of the first inclined portion and the surface of the crank pin 5. Therefore, the lubricating oil containing the cavities 9 easily diffuses outwards in the axial direction of the first split bearing 31, and the cavities 9 easily reach the vicinity of the axial end 73E of the first inclined portion. Therefore, cavitation easily occurs on the surface 73S near the axial end 73E.

[0116] Furthermore, unlike the structure of this specific example, when the groove depth D5, groove width W6, and groove cross-sectional area 74 of each first circumferential groove 74 of the first inclined surface 73 are not constant, the pressure of the oil pressed and flowing into each first circumferential groove 74 will not be the same simultaneously when the surface of the crank pin 5 is close to the sliding surface 7. Therefore, the oil flow F1 flowing backward from each first circumferential groove 74 towards the gap S between the surface 73S of the first inclined surface 73 and the surface of the crank pin 5 will not form almost simultaneously. Alternatively, the first circumferential groove 74 with a relatively large groove depth D5, groove width W6, and groove cross-sectional area 74A will not form an oil flow F1 (oil flows circumferentially within the first circumferential groove 74) because the pressure of the flowing oil is not high. Therefore, the cavity 9 is not easily and stably pressed against the surface side of the crank pin 5 near the centerline WC1 of the first half-split bearing 31, and cavitation may sometimes occur on the surface 73S and the groove surface 741.

Claims

1. A sliding bearing for supporting the crankshaft of an internal combustion engine to rotate freely, wherein, The sliding bearing comprises a first and a second split bearing arranged together to form a cylindrical shape. The first and second split bearings have sliding surfaces on their inner diameter sides and back surfaces on their outer diameter sides. The back side is parallel to the axial direction of the first and second half-split bearings. The first and second half-split bearings have circumferential end faces on both sides in the circumferential direction. The first and second half-split bearings have axial end faces at both ends in the axial direction. The second split bearing has an oil groove on its inner diameter side, the oil groove being located between the two axial end faces of the second split bearing and extending circumferentially, having a constant axial length W1. The oil tank has groove ends at both ends in the axial direction. The sliding surface of the second half-split bearing has two second inclined surfaces, which are adjacent along the entire circumferential length of each of the groove ends and have a constant axial length W2. The surfaces of the second inclined surfaces are displaced in a manner that continuously approaches the back surface from the axial end face side toward the groove end. The surface of the second inclined portion includes: a central region adjacent to the end of the groove; and an edge region adjacent to the central region and located further along the axial end face of the second half-split bearing than the central region. There is a bend at the boundary between the central region and the edge region. When viewed in cross-section along the axial direction of the second half-split bearing, the central region forms a convex curve that protrudes towards the outer diameter side of the second half-split bearing. When viewed in cross-section along the axial direction of the second half-split bearing, the edge region forms a convex curve protruding towards the inner diameter side of the second half-split bearing. A plurality of second circumferential grooves are formed adjacent to each other on the surface of the second inclined portion. These grooves extend over the entire circumferential length of the surface of the second inclined portion and over the entire width of the surface. In a cross-sectional view along the axial direction of the second half-split bearing, the second circumferential grooves have curved groove surfaces. Tops are formed between adjacent groove surfaces, and the curve connecting these tops represents the surface of the second inclined portion. The width of the second circumferential groove is defined as the length of an imaginary straight line connecting the tops of both sides of the second circumferential groove. The groove centerline is defined as a line extending through the center of the length of the imaginary straight line in a direction perpendicular to the imaginary straight line. The groove depth of the second circumferential groove is defined as the length from the imaginary straight line to the point on the groove surface furthest from the imaginary straight line in a direction perpendicular to the imaginary straight line. The maximum groove depth of the second circumferential groove is located on the groove centerline. The area enclosed by the imaginary straight line and the groove surface is defined as the groove cross-sectional area. The groove width, groove depth, and groove cross-sectional area of ​​the plurality of second circumferential grooves are all the same to each other, and the groove width, groove depth, and groove cross-sectional area of ​​the second circumferential grooves are the same at any position in the circumferential direction. The angle between the perpendicular line extending from the surface of the second inclined portion, orthogonal to the axis of the semi-split bearing, and the center line of the groove is defined as the groove inclination angle θ1. The center line of the groove on the surface of the second inclined surface passes through the center of the width of the oil groove along its axial direction and is inclined relative to the vertical line toward the center line extending circumferentially. The groove inclination angle θ1 of the edge region is the smallest at the end of the second inclined surface along its axial direction and increases continuously closer to the bend. The groove inclination angle θ1 of the central region is the smallest at the position adjacent to the end of the groove on the second inclined surface and increases continuously closer to the bend.

2. The sliding bearing as described in claim 1, characterized in that, The edge region of the second inclined face is adjacent to the axial end face of the second half-split bearing.

3. The sliding bearing as described in claim 1 or 2, characterized in that, The width W2C of the central region of the second sloping face is more than 25% and less than 75% of the width W2 of the second sloping face.

4. The sliding bearing as described in claim 1 or 2, characterized in that, The depth D2 of the second tilted face is greater than 0.005 mm and less than 0.050 mm.

5. The sliding bearing as described in claim 1 or 2, characterized in that, The groove depth D3 of the second circumferential groove is greater than 1.5 μm and less than 10 μm.

6. The sliding bearing as described in claim 1 or 2, characterized in that, The groove width W3 of the second circumferential groove is greater than 0.05 mm and less than 0.25 mm.

7. The sliding bearing as described in claim 1 or 2, characterized in that, The groove inclination angle θ1 of the second circumferential groove closest to the bend of the second inclined surface is greater than the groove inclination angle θ1 of the second circumferential groove closest to the end of the groove by a value in the range of more than 0.001° and less than 7°.

8. The sliding bearing as described in claim 1 or 2, characterized in that, The groove inclination angle θ1 of the second circumferential groove closest to the bend of the second inclined surface is greater than the groove inclination angle θ1 of the second circumferential groove closest to the axial end of the second inclined surface by a value in the range of more than 0.001° and less than 7°.

9. The sliding bearing as described in claim 1 or 2, characterized in that, The first split bearing has a centerline that passes through the center of its axial length and extends circumferentially. The sliding surface of the first split bearing has two first inclined surfaces adjacent to the centerline, each having a constant axial length W5 from the centerline toward its respective axial end face, and extending over the entire circumferential length of the first split bearing. The surfaces of the first inclined surfaces are displaced in a manner that continuously approaches the back surface from each axial end face toward the groove end. The surface of the first inclined portion includes: a central region adjacent to the centerline of the first split bearing; and an edge region adjacent to the central region and located further along the axial end face of the first split bearing than the central region. There is a bend at the boundary between the central region and the edge region. When viewed in cross-section along the axial direction of the first half-split bearing, the central region forms a convex curve that protrudes towards the outer diameter side of the first half-split bearing. When viewed in cross-section along the axial direction of the first half-split bearing, the edge region forms a convex curve protruding towards the inner diameter side of the first half-split bearing. A plurality of first circumferential grooves are formed adjacent to each other on the surface of the first inclined portion. The plurality of first circumferential grooves are formed over the entire circumferential length of the surface of the first inclined portion and over the entire width of the surface of the first inclined portion. When viewed in cross-section from the axial direction of the first half-split bearing, the first circumferential grooves have curved groove surfaces. Tops are formed between adjacent groove surfaces. The curve formed by connecting the tops represents the surface of the first inclined portion. The width of the first circumferential groove is defined as the length of an imaginary straight line connecting the tops of both sides of the first circumferential groove. The groove centerline is defined as a line extending through the center of the length of the imaginary straight line in a direction perpendicular to the imaginary straight line. The groove depth of the first circumferential groove is defined as the length from the imaginary straight line to the point on the groove surface furthest from the imaginary straight line in a direction perpendicular to the imaginary straight line. The maximum groove depth of the first circumferential groove is located on the groove centerline. The area enclosed by the imaginary straight line and the surface of the groove is defined as the cross-sectional area of ​​the groove. The groove width, groove depth, and groove cross-sectional area of ​​the plurality of first circumferential grooves are all the same to each other, and the groove width, groove depth, and groove cross-sectional area of ​​the first circumferential grooves are the same at any position in the circumferential direction. The angle between the perpendicular line extending from the surface of the first inclined portion orthogonal to the axis of the split bearing and the center line of the groove is defined as the groove inclination angle θ2. The center line of the groove on the surface of the first inclined portion is inclined relative to the perpendicular line toward the center line of the first split bearing. The groove inclination angle θ2 in the edge region is smallest at the axial end of the first inclined portion and increases continuously closer to the bend. The groove inclination angle θ2 in the central region is smallest at the position adjacent to the center line of the first split bearing and increases continuously closer to the bend.

10. The sliding bearing as described in claim 9, characterized in that, The edge region of the first inclined face is adjacent to the axial end face of the first half-split bearing.

11. The sliding bearing as described in claim 9, characterized in that, The axial length W7 is the sum of the axial lengths W5 of the two first inclined surfaces of the first half-split bearing, and the axial length W4 is the sum of the axial lengths W1 of the two second inclined surfaces W2 of the second half-split bearing and the oil groove. The axial length W7 is the same as the axial length W4.

12. The sliding bearing as described in claim 9, characterized in that, The width W5C of the central region of the first inclined face is more than 25% and less than 75% of the width W5 of the first inclined face.

13. The sliding bearing as described in claim 9, characterized in that, The depth D4 of the first tilted face is greater than 0.005 mm and less than 0.050 mm.

14. The sliding bearing as described in claim 9, characterized in that, The groove depth D5 of the first circumferential groove is greater than 1.5 μm and less than 10 μm.

15. The sliding bearing as described in claim 9, characterized in that, The width W6 of the first circumferential groove is greater than 0.05 mm and less than 0.25 mm.

16. The sliding bearing as claimed in claim 9, characterized in that, The groove inclination angle θ2 of the first circumferential groove closest to the bend of the first inclined surface is greater than the groove inclination angle θ1 of the first circumferential groove closest to the centerline of the first half-split bearing by a value in the range of more than 0.001° and less than 7°.

17. The sliding bearing as claimed in claim 9, characterized in that, The groove inclination angle θ2 of the first circumferential groove closest to the bend of the first inclined surface is greater than the groove inclination angle θ2 of the first circumferential groove closest to the axial end of the first inclined surface by a value in the range of 0.001° to 7°.

Images