Reciprocating unit

Abstract

To provide a reciprocation unit capable of suppressing metal contact in a high load portion.SOLUTION: A reciprocation unit 1 includes a piston 10, a connecting rod 20, and a connecting rod bearing 30. A high load portion 30H is formed in the connecting rod bearing 30. The connecting rod bearing 30 has a bearing surface S which is brought into contact with a crankshaft 2 via oil. An oil retaining recession 32 which is outwardly recessed in a radial direction and can retain the oil is formed on the bearing surface S in the high load portion 30H. The oil retaining recession 32 has an edge formed at a position separated from an end in an axial direction of the connecting rod bearing on the bearing surface S.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to a shuttle unit. [Background technology]

[0002] For example, Japanese Patent Application Laid-Open Publication No. 2018-128070 discloses a half bearing that is butted against another half bearing to form a cylindrical sliding bearing. The half bearing has a plurality of grooves formed on its inner peripheral surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-128070 Summary of the Invention [Problem to be solved by the invention]

[0004] When a half bearing such as that described in JP 2018-128070 A is used as a connecting rod bearing, there is a concern that metal-to-metal contact may occur. Specifically, the connecting rod bearing has a high-load section that is subjected to high loads when an explosion load acts on the piston and connecting rod due to an explosion in the cylinder. In this high-load section, an oil film may not be properly maintained between the crankshaft and the connecting rod bearing, which may result in metal-to-metal contact.

[0005] An object of the present invention is to provide a reciprocating unit capable of suppressing metal contact in a highly loaded portion. [Means for solving the problem]

[0006] A reciprocating unit according to one aspect of the present disclosure includes a piston that reciprocates within a cylinder, a connecting rod that connects the piston to a crankshaft, and a cylindrical connecting rod bearing that supports the connecting rod, wherein the connecting rod bearing is formed with a high load portion that is subjected to a high load when an explosion load acts on the piston and the connecting rod due to an explosion within the cylinder, the connecting rod bearing has a bearing surface that contacts the crankshaft via oil, and the bearing surface in the high load portion is formed with an oil retaining recess that is recessed outward in the radial direction of the connecting rod bearing and is capable of retaining the oil, and the oil retaining recess has an edge portion formed on the bearing surface at a position spaced from the axial end of the connecting rod bearing. [Effects of the Invention]

[0007] According to this disclosure, it is possible to provide a reciprocating unit capable of suppressing metal contact in a high load portion. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a schematic diagram of a reciprocating unit according to an embodiment of the present disclosure. [Figure 2] FIG. 4 is a rear view of the first half bearing. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIGS. 2 and 3. [Figure 5] FIG. 10 is a diagram schematically illustrating a modified example of the reciprocating unit. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the accompanying drawings, in which the same or corresponding elements are designated by the same reference numerals.

[0010] 1 is a diagram schematically illustrating a reciprocating unit 1 according to an embodiment of the present disclosure. The reciprocating unit 1 constitutes a part of an engine.

[0011] As shown in FIG. 1, the reciprocating unit 1 includes a piston 10, a connecting rod 20, and a connecting rod bearing 30.

[0012] The piston 10 moves back and forth linearly (up and down in FIG. 1) within a cylinder (not shown).

[0013] The connecting rod 20 connects the piston 10 to the crankshaft 2. The reciprocating movement of the piston 10 is transmitted to the crankshaft 2 via the connecting rod 20, causing the crankshaft 2 to rotate.

[0014] The connecting rod bearing 30 is formed in a cylindrical shape and receives the connecting rod 20. The connecting rod bearing 30 has a bearing surface S that comes into contact with the crankshaft 2 via oil. The bearing surface S is formed by the inner circumferential surface of the connecting rod bearing 30. The central axis AX1 of the connecting rod bearing 30 substantially coincides with the central axis AX1 of the crankshaft 2. As shown in FIGS. 2 and 3 , the bearing surface S has a central portion SC that is located in the axial center of the connecting rod bearing 30.

[0015] As shown in Figure 1, the connecting rod bearing 30 has a first half bearing 30A and a second half bearing 30B. Each half bearing 30A, 30B is a so-called plain bearing formed in the shape of a half cylinder. The first half bearing 30A is disposed between the crankshaft 2 and the connecting rod 20. The second half bearing 30B, together with the first half bearing 30A, surrounds the periphery of the crankshaft 2.

[0016] The connecting rod bearing 30 is formed with a high load portion 30H that is subjected to a high load when an explosion load acts on the piston 10 and the connecting rod 20 due to an explosion inside the cylinder. In this embodiment, the high load portion 30H is formed in the first half bearing 30A. The high load portion 30H is formed in an area of the first half bearing 30A that faces the piston 10 across the connecting rod 20. Depending on the design of each component, the high load portion 30H may also be formed in an area other than the above area.

[0017] As shown in FIGS. 1 to 4, an oil retention recess 32 capable of retaining oil is formed in the bearing surface S of the high load section 30H. The oil retention recess 32 has a shape that is recessed outward in the radial direction of the connecting rod bearing 30 (upward in FIGS. 3 and 4). As shown in FIGS. 3 and 4, the oil retention recess 32 has a shape that is curved so as to be convex outward in the radial direction. As shown in FIG. 2, the oil retention recess 32 is formed in an area that straddles the center portion SC of the bearing surface S. The length of the oil retention recess 32 in the circumferential direction of the connecting rod bearing 30 is greater than the length of the oil retention recess 32 in the axial direction. As shown in FIG. 2, the outer shape of the oil retention recess 32 when viewed from the center axis AX1 of the crankshaft 2 is elliptical. However, the outer shape of the oil retention recess 32 is not limited to elliptical.

[0018] 2 to 4, the oil retaining recess 32 has a deepest part 32a that has the largest radial outward recess amount T. The deepest part 32a is located at the center SC of the bearing surface S. As shown in FIG. 4, the recess amount T refers to the distance between an imaginary plane S1 of the bearing surface S (a plane that would exist if the oil retaining recess 32 were not formed on the bearing surface S) and the deepest part 32a. For example, the recess amount T is set to 100 μm or less.

[0019] 2 and 4, the oil retaining recess 32 has an edge 32b. The edge 32b is formed at a position on the bearing surface S that is spaced apart from the end of the bearing surface S in the axial direction of the connecting rod bearing 30. A distance L2 (see FIG. 4) between the end of the bearing surface S in the axial direction of the connecting rod bearing 30 and the edge 32b is set to, for example, about 5% to 20% of the length L1 of the bearing surface S in the axial direction.

[0020] As described above, in the reciprocating unit 1 of this embodiment, the oil retaining recess 32 is formed in the bearing surface S of the high load section 30H, and the edge 32b of the oil retaining recess 32 is spaced apart from the end of the connecting rod bearing 30, so that an oil film is effectively maintained between the high load section 30H and the crankshaft 2. This prevents metal contact in the high load section 30H.

[0021] In the above embodiment, the second half bearing 30B may be formed with the oil retaining recess 32. Also, grooves or the like may be formed in portions of the bearing surface S other than the oil retaining recess 32.

[0022] 5, the connecting rod 20 in the reciprocating unit 1 may be configured as a so-called diagonally split connecting rod. In this case, the high load portion 30H is formed in a region of the first half bearing 30A that faces the piston 10 with the connecting rod 20 interposed therebetween, and the oil-retaining recess 32 is formed in the bearing surface S of the high load portion 30H.

[0023] [Aspect] It will be appreciated by those skilled in the art that the exemplary embodiments and examples described above are examples of the following aspects.

[0024] A reciprocating unit according to one aspect of the present disclosure includes a piston that reciprocates within a cylinder, a connecting rod that connects the piston to a crankshaft, and a cylindrical connecting rod bearing that supports the connecting rod, wherein the connecting rod bearing is formed with a high load portion that is subjected to a high load when an explosion load acts on the piston and the connecting rod due to an explosion within the cylinder, the connecting rod bearing has a bearing surface that contacts the crankshaft via oil, and the bearing surface in the high load portion is formed with an oil retaining recess that is recessed outward in the radial direction of the connecting rod bearing and is capable of retaining the oil, and the oil retaining recess has an edge portion formed on the bearing surface at a position spaced from the axial end of the connecting rod bearing.

[0025] In this reciprocating unit, an oil-retaining recess is formed in the bearing surface of the high-load section, and the edge of the oil-retaining recess is spaced apart from the end of the connecting rod bearing, effectively maintaining an oil film between the high-load section and the crankshaft, thereby suppressing metal-to-metal contact in the high-load section.

[0026] It is also preferable that the bearing surface has a central portion located at the center in the axial direction, and the oil retaining recess is formed in a range spanning the central portion.

[0027] In this embodiment, an oil film is more reliably maintained between the high load portion and the crankshaft.

[0028] In this case, it is preferable that the oil retaining recess has a deepest portion that is recessed outwardly in the radial direction by the greatest amount, and that the deepest portion is located in the central portion.

[0029] It is also preferable that the length of the oil retaining recess in the circumferential direction of the connecting rod bearing is greater than the length of the oil retaining recess in the axial direction.

[0030] In this way, an oil film is more reliably maintained between the high load portion and the crankshaft.

[0031] In this case, it is preferable that the oil retaining recess has an elliptical outer shape when viewed from the center axis of the crankshaft.

[0032] Preferably, the oil retaining recess has a shape that is curved so as to be convex outward in the radial direction.

[0033] It should be noted that the embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims rather than the description of the above embodiments, and further includes all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0034] 1 reciprocating unit, 2 crankshaft, 10 piston, 20 connecting rod, 30 connecting rod bearing, 30A first half bearing, 30B second half bearing, 30H high load portion, 32 oil retaining recess, 32a deepest portion, 32b edge portion, S bearing surface, AX1 central axis, SC central portion.

Claims

1. A piston that reciprocates within a cylinder, a connecting rod connecting the piston and a crankshaft; a connecting rod bearing formed in a cylindrical shape and receiving the connecting rod; The connecting rod bearing is a first half bearing disposed between the crankshaft and the connecting rod; a second half bearing that, together with the first half bearing, surrounds the periphery of the crankshaft, the first half bearing is formed with a high load portion on which a high load acts when an explosion load acts on the piston and the connecting rod due to an explosion in the cylinder, the connecting rod bearing has a bearing surface that contacts the crankshaft via oil, an oil retaining recess portion is formed in the bearing surface of the high load portion, the oil retaining recess portion having a shape recessed outward in the radial direction of the connecting rod bearing and capable of retaining the oil, The oil retaining recess is a pair of axial edge portions formed on the bearing surface of the first half bearing at positions spaced apart from each end of the connecting rod bearing in the axial direction; a pair of circumferential edge portions formed on the bearing surface of the first half bearing at positions spaced apart from each end of the connecting rod bearing in the circumferential direction, a length of the oil retaining recess in the circumferential direction of the connecting rod bearing is greater than a length of the oil retaining recess in the axial direction.

2. The bearing surface has a central portion located at a center in the axial direction, The reciprocating unit according to claim 1 , wherein the oil-retaining recess is formed in a range spanning the central portion.

3. the oil retaining recess has a deepest portion that is recessed outwardly in the radial direction by the largest amount, 3. The reciprocating unit according to claim 2, wherein the deepest portion is located in the central portion.

4. 2. The reciprocating unit according to claim 1, wherein the oil retaining recess has an elliptical outer shape when viewed from the center axis of the crankshaft.

5. 5. The reciprocating unit according to claim 1, wherein the oil retaining recess has a shape that is curved so as to be convex outward in the radial direction.

6. 2. The reciprocating unit according to claim 1, wherein the length of the oil retaining recess in the circumferential direction is smaller than the length in the circumferential direction between one end of the bearing surface of the first half bearing in the circumferential direction and one of the pair of circumferential edge portions, and is also smaller than the length in the circumferential direction between the other end of the bearing surface of the first half bearing in the circumferential direction and the other of the pair of circumferential edge portions.

Images