Semi-split bearing and plain bearing

Abstract

A semi-split bearing that constitutes a sliding bearing that is less likely to be damaged during operation of an internal combustion engine is provided. The semi-split bearing includes at least one protrusion that protrudes from an outer peripheral surface to a radially outer side. A recess that is recessed from the outer peripheral surface to a radially inner side is formed in the entire range of a circumferential length between the protrusion and a circumferential end surface of the semi-split bearing. Two radial grooves are formed in the circumferential end surface of the semi-split bearing with respect to the protrusion, and are respectively adjacent to each of the recess side surfaces. The radial grooves extend in the radial direction along the recess side surfaces, and are separated from the recesses midway through the extension. An inner peripheral surface side end portion of the extension direction of the radial grooves is located between a recess bottom surface and an inner peripheral surface of the semi-split bearing. A groove width and a groove depth of the radial grooves decrease from a position separated from the recess toward the inner peripheral surface side end portion, and become zero at the inner peripheral surface side end portion.

Description

Technical Field

[0001] This invention relates to a split bearing that constitutes a sliding bearing supporting the crankshaft of an internal combustion engine. The invention also relates to a cylindrical sliding bearing comprising the aforementioned split bearing 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 an oil pump is fed 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. 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. Thus, lubricating oil fed from the oil passage in the cylinder wall through the through-hole into the lubricating oil groove formed on the inner circumferential surface of the main bearing is supplied via the first, second, and third lubricating oil passages, and from the outlet opening at the end of the third lubricating oil passage to the sliding surface between the crank pin and the connecting rod bearing consisting 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 connecting rod bearing.

[0003] A main bearing and a connecting rod bearing, each consisting of a pair of split bearings, are held in a cylindrical bearing retaining hole in a bearing housing. The bearing housing is composed of a pair of housing segments, each having a semi-cylindrical surface that, when combined, forms the bearing retaining hole. The split bearing is held in this semi-cylindrical surface. The split bearing includes a protrusion that projects radially outward from an outer circumferential surface near a circumferential end face. A recess with a rectangular cross-section is formed between the protrusion and the circumferential end face, recessed radially inward from the outer circumferential surface. The bearing retaining hole (semi-cylindrical surface) of the housing segment has a groove (recess) extending circumferentially from the circumferential end of the semi-cylindrical surface. By receiving the protrusion of the split bearing in the groove of the bearing retaining hole, the split bearing is positioned in a predetermined position in the axial direction within the bearing retaining hole of the bearing housing (for example, see Patent Documents 2, 3, and 4).

[0004] However, in recent years, the pursuit of weight reduction for the purpose of lower fuel consumption in internal combustion engines has led to a tendency to reduce the rigidity of bearing housings such as connecting rods and engine blocks. Therefore, during engine operation, due to the inertial force applied to the bearing housing or the dynamic load from the crankshaft, the bearing retaining hole of the cylindrical bearing housing undergoes repeated elastic deformation, with its vertical inner diameter becoming larger than its horizontal inner diameter, and then returning to a cylindrical shape (closing phenomenon). (Here, the horizontal direction refers to the direction connecting the two segmented surfaces of the bearing housing when viewed from the axis of the bearing retaining hole. The vertical direction is orthogonal to the direction connecting the two segmented surfaces of the segmented bearing housing). When the inner diameter of the bearing retaining hole of the bearing housing increases vertically, a gap sometimes momentarily forms between the segmented surfaces of the pair of segmented bearing housings. When the dividing surfaces of the housing segments come into contact with each other again, the circumferential end faces of the half-segment bearings held in each housing segment are forcefully pushed against each other, applying a large load near the circumferential end faces of the half-segment bearings.

[0005] Conventional split bearings, as described in Patent Documents 2 to 4 above, which have protrusions and recesses for positioning relative to the bearing housing, are prone to damage (cracking) near the recesses on the circumferential end face when the bearing housing closes during internal combustion engine operation, due to the load applied to the circumferential end face of the split bearing.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 8-277831

[0009] Patent Document 2: Japanese Patent Application Publication No. 59-50226

[0010] Patent Document 3: Japanese Patent Application Publication No. 2019-190551

[0011] Patent Document 4: Japanese Patent Application Publication No. 2013-11333 Summary of the Invention

[0012] The object of the present invention is to provide a split bearing that constitutes a sliding bearing for the crankshaft of an internal combustion engine that is less prone to such damage during operation of the internal combustion engine, and a sliding bearing including the split bearing.

[0013] To address the aforementioned technical problems, the present invention provides a semi-split bearing, which constitutes a sliding bearing supporting the crankshaft of an internal combustion engine. The semi-split bearing is characterized by having a semi-cylindrical shape and possessing an inner circumferential surface and an outer circumferential surface.

[0014] The split bearing includes at least one protrusion that projects radially outward from the outer peripheral surface.

[0015] Within the entire circumferential length between the protrusion and the circumferential end face of the split bearing, a recess is formed that extends radially inward from the outer circumferential surface.

[0016] The protrusion is located between the two end faces in the axial direction of the split bearing.

[0017] When viewed through a section parallel to the circumferential end face, the recess has: a bottom surface parallel to the axial direction of the split bearing; two side surfaces orthogonal to the axial direction of the split bearing at both ends of the recess along the axial direction of the split bearing; and two curved surfaces connecting the side surfaces and the bottom surface of the recess.

[0018] Relative to the protrusion, two radial grooves are formed on the circumferential end face of the split bearing, and the two radial grooves are adjacent to the side surfaces of the respective recesses.

[0019] The extension length L3 of the radial groove is greater than the depth D1 of the recess.

[0020] The radial groove extends radially from the outer circumferential surface of the split bearing toward the inner circumferential surface, along the side of the recess, and separates from the recess midway through its extension.

[0021] The inner circumferential end of the radial groove is located between the bottom surface of the recess and the inner circumferential surface of the split bearing.

[0022] The width W3 and depth D2 of the radial groove decrease from the position separated from the concave part toward the inner circumferential end, and become zero at the inner circumferential end.

[0023] In another embodiment of the invention, the groove depth D2 of the radial groove at the position separated from the concave portion is 0.03 to 0.15 mm.

[0024] In another embodiment of the invention, the width W3 of the radial groove at the position separated from the concave portion is 0.1 to 0.3 mm.

[0025] In another embodiment of the invention, the extension length L3 of the radial groove is 0.05 to 0.8 mm greater than the depth D1 of the recess.

[0026] In another aspect, the present invention provides a sliding bearing that is cylindrical, includes the aforementioned split bearing, and supports the crankshaft of an internal combustion engine.

[0027] In another embodiment of the present invention, the sliding bearing is composed of a combination of the aforementioned split bearings. Attached Figure Description

[0028] Figure 1 This is a schematic diagram showing the bearing assembly of the crankshaft.

[0029] Figure 2 This is a perspective view of a split bearing, a specific example of the present invention.

[0030] Figure 2A This is a perspective view of the protrusions, recesses, and radial grooves of an embodiment of the present invention.

[0031] Figure 3 From the direction perpendicular to the circumferential end face ( Figure 2 A diagram showing the protrusions, recesses, and radial grooves of an embodiment of the present invention, viewed from the direction of the Y1 arrow.

[0032] Figure 4 From the axial direction ( Figure 2 A diagram showing the protrusions, recesses, and radial grooves of an embodiment of the present invention, viewed from the direction of the Y2 arrow.

[0033] Figure 5 From the outer peripheral side ( Figure 2 A diagram showing the protrusions, recesses, and radial grooves of an embodiment of the present invention, viewed from the direction of arrow Y3.

[0034] Figure 6 This is a diagram of the radial groove at the location separated from the concave part, observed in a cross-section along the axial direction of the split bearing.

[0035] Figure 7 This is a diagram showing the bearing housing.

[0036] Figure 8 This is a diagram showing the bearing housing during elastic deformation.

[0037] Figure 9 This is a diagram illustrating the function of the present invention.

[0038] Figure 10 This is a diagram of the recessed portion in the prior art.

[0039] Figure 11 This is a diagram of the concave portion of the comparative example.

[0040] Figure 12 This is a diagram of the concave portion of another comparative example.

[0041] Figure 13 This is a diagram of the concave portion of another comparative example.

[0042] Figure 14 This is a diagram of the concave portion of another comparative example.

[0043] Symbol Explanation

[0044] 1. Bearing assembly;

[0045] 2. Linkage;

[0046] 3. Connecting rod bearings;

[0047] 4. Main bearing;

[0048] 5. Crank pin;

[0049] 5a and 5b are lubrication circuits.

[0050] 5c Discharge outlet;

[0051] 6. Journal neck;

[0052] 6a Lubrication circuit;

[0053] 6c Inlet opening;

[0054] 10. Bearing housing;

[0055] 101. Shell segmentation;

[0056] 102. Shell segmentation;

[0057] 21 Bearing housing

[0058] 22. Shell segmentation;

[0059] 23. Shell segmentation;

[0060] 25 dividing surfaces;

[0061] 26. Bearing retaining hole;

[0062] 27. Semi-cylindrical surface;

[0063] 31, 32 Half-split bearings;

[0064] 41, 42 Half-split bearings;

[0065] 41a Oil tank;

[0066] 70 Inner circumference;

[0067] 71. Outer perimeter;

[0068] 72. Protrusion;

[0069] 721 Protruding circumferential surface;

[0070] 722 Protruding side;

[0071] 76 Circumferential end face

[0072] 77. End face in the axial direction;

[0073] 8 recess;

[0074] 81 bottom surface of concave part;

[0075] 82 concave side;

[0076] 83 concave surface;

[0077] 9. Radial grooves;

[0078] 91. The inner circumferential end of the radial groove;

[0079] D1 Depth of the recess;

[0080] D2 is the groove depth of the radial groove;

[0081] DH bearings maintain the horizontal inner diameter of the bore.

[0082] The DV bearing retains the inner diameter of the bore in the vertical direction;

[0083] P indicates a separate position;

[0084] W1 is the width of the protrusion;

[0085] W2 is the width of the concave portion;

[0086] W3 is the width of the radial groove;

[0087] The height of the L1 protrusion;

[0088] L2 is the length of the concave portion;

[0089] L3 is the extension length of the radial groove;

[0090] L4 is the length of the protrusion and recess;

[0091] T represents the thickness at the circumferential end face of the split bearing;

[0092] Z: The direction of rotation of the crank pin;

[0093] The direction of rotation of the X-axis journal. Detailed Implementation

[0094] Hereinafter, specific examples of the present invention will be described with reference to the accompanying drawings.

[0095] Figure 1The 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 the cylinder block; a crank pin 5 integrally formed with the journal 6 and rotating about 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 in a freely rotatable manner, and the connecting rod bearing 3 supports the crank pin 5 in a freely rotatable manner.

[0096] 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 and explained here. Figure 1 In the paper, regarding the positional relationship in the depth direction, the journal 6 is located on the inside of the paper, and the crank pin 5 is located on the front side.

[0097] The journal journal 6 is supported by a main bearing 4, consisting of a pair of split bearings 41 and 42, on the bearing housing 10 (cylinder block 101 and cover 102) at the lower part of the internal combustion engine cylinder block. Figure 1 In the upper half-split bearing 41, an oil groove 41a is formed along the entire length of its inner circumference. 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 41a of the main bearing 4.

[0098] The crank pin 5 is supported by the connecting rod 2's bearing housing 21 (rod-side large end housing 22 and cover-side large end housing 23) via a connecting rod bearing 3 consisting of a pair of split bearings 31 and 32.

[0099] The bearing housing 10 is composed of a pair of housing segments 101 and 102. The housing segments 101 and 102 have semi-cylindrical surfaces 27, which form cylindrical bearing retaining holes 26 when the dividing surfaces 25 of the pair of housing segments 101 and 102 are mated. The semi-segmented bearings 41 and 42 are held in each of the semi-cylindrical surfaces 27.

[0100] Similarly, the bearing housing 21 is composed of a pair of housing segments 22 and 23. The housing segments 22 and 23 have semi-cylindrical surfaces 27, which form cylindrical bearing retaining holes 26 when the dividing surfaces 25 of the pair of housing segments 22 and 23 are mated. The semi-segmented bearings 31 and 32 are held in each of the semi-cylindrical surfaces 27.

[0101] 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 and the through-hole formed in the wall of the main bearing 4 and is sent into the oil groove 41a formed along the inner circumferential surface of the main bearing 4.

[0102] Furthermore, a first lubricating oil passage 6a is formed through the journal 6 along the diameter direction, and the inlet opening 6c of the first lubricating oil passage 6a is formed to communicate with the lubricating oil groove 41a. A second lubricating oil passage 5a is formed branching from the first lubricating oil passage 6a of the journal 6, passing through the crank arm (not shown). The second lubricating oil passage 5a is connected to a third lubricating oil passage 5b formed through the journal 5 along the diameter direction of the crank pin 5.

[0103] 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.

[0104] In recent years, the pursuit of weight reduction and lower fuel consumption in internal combustion engines has led to a tendency to reduce the rigidity of bearing housings such as connecting rod 2 and engine block 101. Therefore, during engine operation, due to inertial forces applied to the bearing housings 10 and 21 or dynamic loads from the crankshaft, the bearing retaining holes 26 of the cylindrical bearing housings 10 and 21 undergo repeated elastic deformation, with the vertical inner diameter DV becoming larger than the horizontal inner diameter DH (refer to...). Figure 8 ) and elastic deformation to return to a cylindrical shape (see reference) Figure 7 The phenomenon is referred to as the "closing phenomenon." Here, the horizontal direction refers to the direction connecting the two segmented surfaces 25 of the bearing housing segments 101, 102, 22, and 23 when viewed from the axial direction of the bearing retaining hole 26. The vertical direction refers to the direction orthogonal to the direction connecting the two segmented surfaces 25 of the bearing housing segments 101, 102, 22, and 23 when viewed from the axial direction of the bearing retaining hole 26.

[0105] When the inner diameter of the bearing retaining hole 26 in the bearing housing 10, 21 increases in the vertical direction, a gap sometimes momentarily forms between the dividing surfaces 25 of the pair of housing segments 101, 102, 22, 23 of the bearing housing 10, 21. When the dividing surfaces 25 of the housing segments 101, 102, 22, 23 come into contact with each other again, the circumferential end faces 76 of the half-segment bearings 41, 42, 31, 32 held in each housing segment 101, 102, 22, 23 are forcefully pushed against each other, and a large load is applied near the circumferential end faces 76 of the half-segment bearings 41, 42, 31, 32.

[0106] The prior art split bearing includes a protrusion 72A that protrudes radially outward from an outer peripheral surface 71 near a circumferential end face 76. A recess 8A with a rectangular cross-section is formed between the protrusion 72A and the circumferential end face 76, recessed radially inward from the outer peripheral surface 71. A groove (recess) extending circumferentially from the circumferential end of the semi-cylindrical surface is formed in the bearing retaining hole (semi-cylindrical surface) of the housing split. By receiving the protrusion 72A of the split bearing in the groove of the bearing retaining hole, the split bearing is positioned in a predetermined position in the axial direction within the bearing retaining hole (for example, see Patent Documents 2, 3, and 4).

[0107] Figure 10 The figure shows the protrusion 72A and the recess 8A with a rectangular cross-sectional shape of a prior art split bearing, viewed from a direction perpendicular to the circumferential end face 76. A closing phenomenon occurs within the bearing housings 10 and 21, where the circumferential end faces 76 of the split bearing are forcefully pushed against each other. When a large load is applied near the circumferential end face 76 of the split bearing, stress concentrates in the recess 8A of the prior art split bearing at the corner formed by the bottom surface 81A and the side surface 82A of the recess (see reference). Figure 10 The dotted circle makes the corners prone to damage (cracking).

[0108] This invention addresses the problems of the prior art described above.

[0109] The following describes an example of applying the split 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 split bearing constituting the main bearing 4.

[0110] Alternatively, two of the two semi-split bearings constituting the connecting rod bearing 3 or the main bearing 4 may be used as the semi-split bearings of the present invention. Alternatively, one of the semi-split bearings may be the semi-split bearing of the present invention, and the other may be a conventional semi-split bearing without protrusions and recesses on its outer peripheral surface.

[0111] Figure 2 This illustrates a specific example of the split bearing (connecting rod bearing 3) of the present invention. The connecting rod bearing 3 is formed by integrally assembling a pair of split bearings 31 and 32 into a cylindrical shape by mating their circumferential end faces 76. The inner circumferential surface 70 forming the cylindrical shape is a sliding surface.

[0112] Furthermore, the thickness of the split bearings 31 and 32 is constant in the circumferential direction. However, the thickness may be greatest at the central portion in the circumferential direction and continuously decrease towards the two end faces 76 in the circumferential direction. Additionally, the inner circumferential surface 70 may have compression relief portions at both ends in the circumferential direction.

[0113] Furthermore, the compression buffer is a surface formed at the circumferential end region of the split bearings 31 and 32 by reducing the thickness of the wall portion from the original inner circumferential surface 70 radially. It is formed to absorb, for example, the positional displacement and deformation of the circumferential end face 76 of the split bearings that may occur when assembling a pair of split bearings 31 and 32 to the connecting rod 2. Therefore, the curvature center position of the surface of the compression buffer 72 differs from the curvature center position of the inner circumferential surface 70 in other regions (refer to SAE J506 (items 3.26 and 6.4), DIN 1497, section 3.2, JISD 3102). Generally, in the case of bearings for small internal combustion engines used in passenger cars, the depth of the compression buffer at the circumferential end face of the split bearing (the distance from the original inner circumferential surface to the compression buffer at the circumferential end face 76) is approximately 0.01 to 0.05 mm.

[0114] Figure 2A This is a perspective view of the protrusions, recesses, and radial grooves of an embodiment of the present invention. Figure 3 From the direction perpendicular to the circumferential end face 76 ( Figure 2 The diagram shows the protrusions, recesses, and radial grooves observed (in the direction of the Y1 arrow). Figure 4 From the axial direction ( Figure 2 The diagram shows the protrusions, recesses, and radial grooves observed (in the direction of the Y2 arrow). Figure 5 From the outer peripheral side ( Figure 2 The diagram shows the protrusions, recesses, and radial grooves of an embodiment of the present invention as observed (in the direction of arrow Y3). Of course, the present invention is not limited to this embodiment. Furthermore, for ease of understanding, the protrusions 72, recesses 8, and radial grooves 9 are depicted in an exaggerated manner in the figures.

[0115] The split bearings 31 and 32 each include at least one protrusion 72 that protrudes radially outward from the outer peripheral surface 71 on one side of a circumferential end face 76. The protrusion 72 is formed between the two end faces 77 and 77 in the axial direction of the split bearings 31 and 32. However, the protrusion 72 is formed in a manner that does not contact the axial end face 77. That is, the protrusion 72 is formed with a gap between it and the axial end face 77. The protrusion 72 has protruding side surfaces 722 parallel to the circumferential direction of the split bearings 31 and 32 at both ends in the width direction (axial direction of the split bearings 31 and 32). Furthermore, the protrusion 72 has a protruding circumferential surface 721 parallel to the circumferential end face 76 at its circumferential end face of the split bearings 31 and 32.

[0116] Additionally, the protruding side 722 may also be inclined relative to the circumferential direction of the split bearings 31 and 32. Furthermore, the protruding circumferential surface 721 may also be inclined relative to the circumferential end face 76 of the split bearings 31 and 32.

[0117] In this embodiment, a protrusion 72 and a recess 8 are provided only on the circumferential end face side of one of the split bearings 31 and 32. However, this is not a limitation, and more than one protrusion 72 and recess 8 may be provided on each of the circumferential end face sides of the split bearings 31 and 32.

[0118] In the case of a small internal combustion engine for passenger cars, the width W1 of the protrusion 72 is 1.5 to 5.5 mm, and the height L1 of the protrusion 72 is 0.5 to 3 mm. Furthermore, the height L1 of the protrusion 72 is defined as the radial length between the outer circumferential surface 71 of the circumferential end face 76 of the split bearings 31 and 32 and the farthest radial position of the protrusion 72 (refer to...). Figure 4 The length L4 between the circumferential end face 76 of the split bearings 31 and 32 and the end of the protrusion 72 on the circumferential central side of the split bearings 31 and 32, in the direction perpendicular to the circumferential end face 76, is 2 to 7 mm. Furthermore, the protrusion 72 is not limited to the above dimensions and may be of other dimensions.

[0119] Within the entire circumferential length between the protrusion 72 (circumferential surface 721) and the circumferential end faces 76 of the split bearings 31 and 32, a recess 8 is formed that is radially recessed from the outer circumferential surface 71. When viewed through a section parallel to the circumferential end face 76, the recess 8 has: a bottom surface 81 parallel to the axial direction of the split bearings 31 and 32; two side surfaces 82 orthogonal to the axial direction of the split bearings 31 and 32 at both ends of the recess 8 in the axial direction of the split bearings 31 and 32; and two concave curved surfaces 83 (convex curved surfaces facing the inner diameter side of the split bearings 31 and 32), which connect the respective side surfaces 82 and the bottom surface 81. Furthermore, the recess 8 opens into the circumferential end face 76 of the split bearings 31 and 32.

[0120] The bottom surface 81, side surface 82, and curved surface 83 of the recess 8 extend vertically relative to the circumferential end faces 76 of the split bearings 31 and 32. The end face of the protrusion 72 side of the recess 8 is in the same plane as the circumferential surface 721 of the protrusion. Figure 3 In the diagram, a single-dotted line indicates the position of the outer peripheral surface 71 within the circumferential surface 721 of the protrusion 72 when the outer peripheral surface 71 also exists within the protrusion 72. Figure 3 In the middle, the surface surrounded by the single-dot dashed line, the bottom surface 81 of the concave part, the side surface 82 of the concave part, and the curved surface 83 of the concave part is the end face of the protrusion 72 side of the concave part 8.

[0121] The width W2 of the recess 8 is the same as the width W1 of the protrusion 72. The width W2 of the recess 8 may also be slightly smaller than the width W1 of the protrusion 72. In the case of a small internal combustion engine for passenger cars, the length L2 of the recess 8 is 0.5–3 mm, and the depth D1 of the recess 8 is 0.3–2 mm (wherein, the depth D1 of the recess 8 is less than 60% of the thickness T of the circumferential end face 76 of the split bearings 31 and 32 (D1 ≤ T × 0.6)). The length L2 of the recess 8 is defined as the length perpendicular to the circumferential end face 76 between the circumferential end face 76 of the split bearings 31 and 32 and the end face of the recess 8 on the side of the protrusion 72 (see reference). Figure 4 The depth D1 of the recess is defined as the radial length between the outer circumferential surface 71 of the circumferential end face 76 of the split bearings 31 and 32 and the bottom surface 81 of the recess (refer to...). Figure 4 In addition, the recess 8 is not limited to the above dimensions and may also be other dimensions.

[0122] Two radial grooves 9 are formed on the circumferential end faces 76 of the split bearings 31 and 32 relative to the protrusions 72. Each radial groove 9 is adjacent to a side face 82 of a recess. The radial grooves 9 extend radially from the outer circumferential surface 71 of the split bearings 31 and 32 toward the inner circumferential surface 70 along the side face 82 of the recess. Furthermore, when two or more protrusions 72 are provided in the split bearings 31 and 32, two radial grooves 9 are formed on the circumferential end faces 76 of the split bearings 31 and 32 relative to each protrusion 72. The extension length L3 of the radial groove 9 is greater than the depth D1 of the recess 8. The radial groove 9 separates from the recess 8 (recessed curved surface 83) during its extension. The inner circumferential surface end 91 of the radial groove 9 in the extension direction is located between the bottom surface 81 of the recess and the inner circumferential surface 70 of the split bearings 31 and 32.

[0123] The groove depth of the radial groove 9 decreases from the outer peripheral surface 71 toward the position P where it separates from the recess 8 (recessed surface 83). In addition, the groove width W3 and groove depth D2 of the radial groove 9 decrease from the position P where it separates from the recess 8 (recessed surface 83) toward the inner peripheral surface end 91, and become zero at the inner peripheral surface end 91. Figure 6 The position P, which is separated from the recess 8, is observed at the cross-section along the axial direction of the split bearings 31 and 32. Figure 3 The diagram shows the radial groove 9 at the AA section. In this embodiment, the cross-sectional shape of the radial groove 9 is V-shaped, but it can also be rounded. In addition, the extending direction of the radial groove 9 can also be inclined relative to the radial direction of the split bearings 31 and 32.

[0124] In the case of a small internal combustion engine for passenger cars, the groove depth D2 of the radial groove 9 at position P, which is separated from the recess 8, can be set to 0.03 to 0.15 mm. The groove width W3 of the radial groove 9 at position P, which is separated from the recess 8, can be set to 0.1 to 0.3 mm. In addition, the extension length L3 of the radial groove 9 can be 0.05 to 0.8 mm greater than the depth D1 of the recess 8. However, ideally, the extension length L3 of the radial groove 9 is less than 75% of the thickness (wall thickness) T of the circumferential end face 76 of the split bearing. That is, ideally, a radial groove is not formed, but a circumferential end face with a thickness T of more than 25% of the split bearing is ensured between the inner circumferential end face 91 and the inner circumferential surface 70.

[0125] Furthermore, the groove depth D2 of the radial groove 9 at position P, which is separated from the recess 8, is defined as the length perpendicular to the circumferential end face 76, extending from the deepest point of the radial groove 9. The groove width W3 of the radial groove 9 at position P, which is separated from the recess 8, is defined as the length parallel to the axial direction of the radial groove 9 in the circumferential end face 76, which is parallel to the axis of the half-split bearings 31 and 32. The extension length L3 of the radial groove 9 is defined as the radial length from the outer circumferential surface 71 at the circumferential end face 76 to the inner circumferential surface end 91 of the radial groove 9. Additionally, the radial groove 9 is not limited to the dimensions described above and may have other dimensions.

[0126] In this embodiment, the connecting rod bearing 3 is formed integrally into a cylindrical shape by abutting the circumferential end faces 76 of a pair of split bearings 31 and 32. When a protrusion 72 and a recess 8 are formed only on one side of the circumferential end face 76, generally, the pair of split bearings 31 and 32 are assembled by abutting the circumferential end faces 76 with the protrusion 72 and the recess 8. In this case, the recess 8 of the circumferential end face 76 of one split bearing 31 (32) does not contact the recess 8 of the circumferential end face 76 of the other split bearing 32 (31) (it contacts the circumferential end face 76 where the recess 8 is not formed). The split bearings 31 and 32 can have a sliding layer made of Cu bearing alloy or Al bearing alloy. Alternatively, a sliding layer made of Cu bearing alloy or Al bearing alloy can be formed on a back metal layer made of Fe alloy. In addition, the inner circumferential surface 70, i.e. the sliding surface, and the outer circumferential surface 71 of the cylindrical shape may have a surface portion composed of any one of Bi, Sn, and Pb, which are softer than bearing alloys, or an alloy mainly composed of the aforementioned metals, or a surface portion composed of a resin composition mainly composed of synthetic resin.

[0127] Hereinafter, the reasons why damage (cracking) is less likely to occur near the recess 8 of the circumferential end face 76 will be explained using the half-split bearings 31 and 32 of the present invention as described above.

[0128] As described above, when the internal combustion engine is running, if a closing phenomenon occurs in the bearing housing 21, the circumferential end faces 76 of the split bearings 31 and 32 will be forcefully pushed against each other. However, since the recess 8 of the present invention has a recessed curved surface 83 between the recess bottom surface 81 and the recess side surface 82, a stress concentration area like the corner of the prior art is not formed, and the stress is distributed throughout the recessed curved surface 83. Furthermore, due to the load applied near the recessed curved surface 83, the bearing material near the recessed curved surface 83 undergoes spatial elastic deformation towards the radial groove 9, thereby alleviating the stress applied to the bearing material near the recessed curved surface 83.

[0129] Specifically, when a load is applied near the concave surface 83, the bearing material near the circumferential end face of the portion surrounded by the radial groove 9, the concave surface 81, and the radial groove 9, which is separated from the concave surface 83 by the radial groove 9, and the bottom surface 81 of the concave surface 83 (refer to...). Figure 9 The roughly triangular-shaped shaded area faces the space created by the radial groove 9. Figure 9 (The direction of the blank arrow) elastically deforms, thereby reducing the stress applied to the bearing material on the concave surface 83. Therefore, damage is less likely to occur near the concave portion of the circumferential end face of the split bearings 31 and 32.

[0130] Figure 11 This is a view of the area near the recess 8A on the circumferential end face of the comparative example split bearing, viewed from a direction perpendicular to the circumferential end face. The recess 8A in this comparative example has a radial groove 9A, but the bottom surface 81A and the side surface 82A of the recess 8A are directly connected, and it does not have a recessed curved surface 83. Therefore, a closing phenomenon occurs within the bearing housing 21, and the circumferential end faces 76 of the split bearing are forcefully pushed against each other. When a large load is applied near the circumferential end face 76 of the split bearing, stress concentrates at the corner formed by the bottom surface 81A and the side surface 82A of the recess (see reference 8A). Figure 11 The dotted circle makes the corners prone to damage.

[0131] Figure 12 This is a view of the area near the recess 8A on the circumferential end face of another comparative example of a split bearing, observed from a direction perpendicular to the circumferential end face. In this comparative example, the recess 8A has a concave curved surface 83A between the bottom surface 81A and the side surface 82A of the recess 8A, but lacks the radial groove 9. Therefore, a closing phenomenon occurs within the bearing housing 21, and the circumferential end faces 76 of the split bearing are forcefully pushed against each other. When a large load is applied near the circumferential end face 76 of the split bearing, the bearing material near the concave curved surface 83A cannot achieve the spatial elastic deformation caused by the radial groove 9. Therefore, stress concentrates on the concave curved surface 83A (see reference). Figure 12 The dotted circle (which makes the concave curved surface 83A prone to damage) can easily cause damage.

[0132] Figure 13 This is a view of the area near the recess 8A on the circumferential end face of another comparative example of a split bearing, observed from a direction perpendicular to the circumferential end face. In this comparative example, the recess 8A has a concave curved surface 83A between the bottom surface 81A and the side surface 82A of the recess 8A, and has two radial grooves 9A. However, the extension length L3 of the radial grooves 9A is less than the depth D1 of the recess 8A. Therefore, a closing phenomenon occurs in the bearing housing 21, and the circumferential end faces 76 of the split bearing are forcefully pushed against each other. When a large load is applied near the circumferential end face 76 of the split bearing, the spatial elastic deformation of the bearing material near the curved surface 83A caused by the radial grooves 9A becomes insufficient or completely absent. Therefore, stress concentrates on the curved surface 83A (see reference). Figure 13 The dotted circle makes the curved surface 83A prone to damage.

[0133] Figure 14 This is a perspective view showing the area near the recess 8A on the circumferential end face of a split bearing of another comparative example. In the recess 8A of this comparative example, the bottom surface 81A and the side surface 82A of the recess 8A are directly connected, and there is no recessed curved surface 83. In addition, there is a radial groove 9A, which has a width greater than the width of the recess 8A and has a trapezoidal cross-section. The groove width and groove depth of the radial groove 9A are the largest at the outer circumferential surface and decrease towards the inner circumferential surface. The radial groove 9A has an end 91A at its end on the inner circumferential surface side that is parallel to the axial direction of the split bearing. In the split bearing of this comparative example, a closing phenomenon occurs in the bearing housing 21, and the circumferential end faces 76 of the split bearing are strongly pushed against each other. When a large load is applied near the circumferential end face 76 of the split bearing, the stress will concentrate at the corner formed by the bottom surface 81A and the side surface 82A of the recess, and damage is likely to occur at the corner. Furthermore, stress will also concentrate at the corner where the end 91A of the inner circumferential surface of the radial groove 9A connects to the end face 92A of the radial groove 9A in the width direction (see reference). Figure 14 (The dotted circle) is prone to damage.

[0134] The above description uses the example of applying the split bearing of the present invention to a connecting rod bearing that supports the crank pin of the crankshaft of an internal combustion engine. However, the split bearing of the present invention can also be applied to one or both of a pair of split bearings constituting a main bearing that supports the journal of the crankshaft. Furthermore, the split bearing may also have oil holes and oil grooves.

Claims

1. A split bearing constituting a sliding bearing that supports a crankshaft of an internal combustion engine, characterized by, The half-split bearing has a semi-cylindrical shape, and has an inner peripheral surface and an outer peripheral surface, The half-split bearing includes at least one protrusion that protrudes radially outward from the outer peripheral surface, A recess that is recessed radially inward from the outer peripheral surface is formed in the entire range of the circumferential length between the protrusion and the circumferential end surface of the half-split bearing, The protrusion is located between the axial direction end surfaces of the half-split bearing, When viewed in a cross section parallel to the circumferential end surface, the recess has a recess bottom surface that is parallel to the axial direction of the half-split bearing, two recess side surfaces that are orthogonal to the axial direction of the half-split bearing at both ends of the recess in the axial direction of the half-split bearing, and two recess curved surfaces that connect each of the recess side surfaces and the recess bottom surface, Two radial grooves that are adjacent to each of the recess side surfaces are formed in the circumferential end surface of the half-split bearing with respect to the protrusion, The extension length (L3) of the radial groove is greater than the depth (D1) of the recess, The radial groove extends radially along the recess side surface from the outer peripheral surface of the half-split bearing toward the inner peripheral surface, and the radial groove is separated from the recess halfway through the extension, The inner peripheral surface side end portion of the extension direction of the radial groove is located between the recess bottom surface and the inner peripheral surface of the half-split bearing, The groove width (W3) and the groove depth (D2) of the radial groove decrease from the position separated from the recess toward the inner peripheral surface side end portion, and become zero at the inner peripheral surface side end portion.

2. The half-split bearing according to claim 1, wherein The groove depth (D2) of the radial groove at the position separated from the recess is 0.05 to 0.15 mm.

3. The half-split bearing according to claim 1 or 2, wherein The groove width (W3) of the radial groove at the position separated from the recess is 0.1 to 0.3 mm.

4. The half-split bearing according to claim 1 or 2, wherein The extension length (L3) of the radial groove is greater than the depth (D1) of the recess by 0.05 to 0.8 mm.

5. A sliding bearing, comprising: the half-split bearing according to claim 1 or 2, and The sliding bearing is cylindrical, includes the half-split bearing according to claim 1 or 2, and supports a crankshaft of an internal combustion engine.

6. The sliding bearing according to claim 5, wherein The sliding bearing is composed of pairs of the half-split bearings.

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