Connecting rod of reciprocating fluid machine, and reciprocating fluid machine

Abstract

This connecting rod of a reciprocating fluid machine comprises a large end part that is divided in a circumferential direction with a crank pin as the center, and a metal bearing that is disposed between the crank pin and the large end part and is divided in half in the circumferential direction. The large end part is divided into a neck-part-side large end part connected to a neck part, and a cap part linked to the neck-part-side large end part. The metal bearing is divided into an upper metal of which a circumferential center portion is in contact with a bearing surface of the neck-part-side large end part, and a lower metal of which a circumferential center portion is in contact with a bearing surface of the cap part. In the circumferential direction, the division position of the large end part and the division position of the metal bearing are different from each other.

Description

Connecting rod of a reciprocating fluid machine, and reciprocating fluid machine

[0001] The present disclosure relates to a connecting rod of a reciprocating fluid machine and a reciprocating fluid machine.

[0002] A reciprocating fluid machine including a piston provided reciprocally in a cylinder is known. In such a reciprocating fluid machine, a crankshaft and a piston are connected via a connecting rod (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2013-36381

[0004] The joint surface of the large end portion of the connecting rod and the cap joined to the large end portion, which is connected to the crank pin of the crankshaft, is often provided along a plane orthogonal to the extending direction of the rod portion of the connecting rod. And the positioning of the cap with respect to the large end portion is performed by, for example, a connecting rod bolt which is a reamer bolt.

[0005] However, for the convenience of assembling and disassembling the reciprocating fluid machine, the joint surface between the large end portion of the connecting rod and the cap joined to the large end portion may be provided inclined with respect to the plane orthogonal to the extending direction of the rod portion of the connecting rod. In this case, the following points may be problematic.

[0006] The large end of the connecting rod is circumferentially divided into a rod-side large end connected to the rod section and a cap section joined to the rod-side large end. The through hole for inserting the connecting rod bolt in the rod-side large end extends from the joint surface (hereinafter simply referred to as "the joint surface") in the rod-side large end toward the small end of the connecting rod. If the joint surface is inclined with respect to a plane perpendicular to the extending direction of the rod section, one of the two joint surfaces provided on either side of the crankpin will be closer to the rod section. Therefore, of the ends of the through hole for inserting the connecting rod bolt in one of the joint surfaces, the end on the rod section side will also be closer to the rod section. Therefore, it may become impossible to pass the through hole through the rod-side end to the rod-side big end, and it may become impossible to protrude the tip of the connecting rod bolt from the rod-side big end and fasten it with a nut.

[0007] Therefore, it is conceivable to screw the male threaded portion at the tip of the connecting rod bolt into the female threaded portion provided in the through hole. However, as mentioned above, since one of the joint surfaces approaches the rod portion, it may be difficult to ensure the length of the reamer portion in accordance with the position of the joint surface when trying to ensure the length of the male threaded portion of the connecting rod bolt (the length of the female threaded portion in the through hole). Therefore, positioning using a reamer bolt may be difficult.

[0008] In cases like these, where positioning using a reamer bolt (connecting rod bolt) becomes difficult, it is conceivable to position the cap relative to the big end by providing a separate positioning pin. When positioning with a pin, a pin of a certain size is required to ensure the pin's strength. However, securing space for the pin can be difficult, making pin-based positioning challenging in some cases.

[0009] In view of the above circumstances, at least one embodiment of the present disclosure aims to provide a connecting rod for a reciprocating fluid machine and a reciprocating fluid machine that can position a cap relative to a connecting rod with a relatively simple configuration.

[0010] (1) A connecting rod for a reciprocating fluid machine according to at least one embodiment of the present disclosure is a connecting rod for a reciprocating fluid machine comprising: a large end portion divided circumferentially around the crank pin and connected to the crank pin of a crankshaft; and a metal bearing disposed between the crank pin and the large end portion and divided in half circumferentially, wherein the large end portion is divided into a rod-side large end portion connected to a rod portion and a cap portion connected to the rod-side large end portion; the metal bearing is divided into an upper metal portion whose circumferential central portion is in contact with the bearing surface of the rod-side large end portion and a lower metal portion whose circumferential central portion is in contact with the bearing surface of the cap portion; the division position of the large end portion and the division position of the metal bearing are different in the circumferential direction; when the upper metal portion is positioned relative to the rod-side large end portion, the lower metal portion is positioned relative to the upper metal portion. The cap portion is positioned relative to the upper metal and the lower metal. When the lower metal is positioned relative to the cap portion, the upper metal is positioned relative to the lower metal. The rod-side large end is positioned relative to the upper metal and the lower metal.

[0011] (2) A connecting rod for a reciprocating fluid machine according to at least one embodiment of the present disclosure is a connecting rod for a reciprocating fluid machine comprising: a large end portion divided circumferentially around the crank pin and connected to the crank pin of a crankshaft; and a metal bearing disposed between the crank pin and the large end portion and divided in half circumferentially, wherein the large end portion is divided into a rod-side large end portion connected to a rod portion and a cap portion connected to the rod-side large end portion; the metal bearing is divided into an upper metal portion whose circumferential central portion is in contact with the bearing surface of the rod-side large end portion and a lower metal portion whose circumferential central portion is in contact with the bearing surface of the cap portion; the division position of the large end portion and the division position of the metal bearing are different in the circumferential direction; the relative circumferential position of the upper metal portion and the lower metal portion is positioned by the circumferential end faces of the upper metal portion and the lower metal portion being in contact with each other. The rod-side big end and the upper and lower metals are positioned such that the rod-side big end contacts the upper and lower metals in the radial direction centered on the crankpin, thereby positioning the radial relative positions of the rod-side big end and the upper and lower metals. The cap portion and the upper and lower metals are positioned such that the cap portion contacts the upper and lower metals in the radial direction, thereby positioning the radial relative positions of the cap portion and the upper and lower metals.

[0012] (3) A reciprocating fluid machine according to at least one embodiment of the present disclosure comprises the crankshaft and the connecting rod described in (1) or (2) above, having the large end connected to the crankpin.

[0013] According to at least one embodiment of the present disclosure, the cap can be positioned relative to the connecting rod with a relatively simple configuration.

[0014] This is a schematic longitudinal cross-sectional view of a reciprocating compressor as an example of a reciprocating fluid machine according to one embodiment of the present disclosure. This is an external view of a connecting rod according to several embodiments of the reciprocating compressor. This is a view of the vicinity of the big end of a connecting rod according to several embodiments. This is a view of the rod-side big end and upper metal according to one embodiment. This is a view of the cap portion and lower metal according to one embodiment. This is a view of the cap portion and lower metal according to another embodiment.

[0015] Hereinafter, several embodiments of this disclosure will be described with reference to the attached drawings. However, the dimensions, materials, shapes, relative arrangements, etc., of the components described as embodiments or shown in the drawings are not intended to limit the scope of this disclosure, but are merely illustrative examples. For example, expressions describing relative or absolute arrangements such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" should not only describe such arrangements strictly, but also represent states of relative displacement with tolerances, or angles or distances to the extent that the same function is achieved. For example, expressions describing things being in an equal state such as "identical," "equal," and "homogeneous" should not only describe states of being strictly equal, but also represent states where tolerances, or differences to the extent that the same function is achieved, exist. For example, expressions describing shapes such as square shapes or cylindrical shapes should not only describe geometrically precise square shapes or cylindrical shapes, but also represent shapes including concave and concave parts, chamfered parts, etc., to the extent that the same effect is achieved. On the other hand, expressions such as "to possess," "to be equipped with," "to have," "to include," or "to have" a single component are not exclusive expressions that exclude the existence of other components.

[0016] In the drawings, identical elements are denoted by the same reference numeral, and redundant explanations are omitted. Dimensions, angles, and other parameters in the drawings are exaggerated for illustrative purposes and may differ from actual proportions.

[0017] <1. Overview of the Reciprocating Compressor 1> Figure 1 is a schematic longitudinal cross-sectional view of a reciprocating compressor 1 as an example of a reciprocating fluid machine according to one embodiment of the present disclosure. The reciprocating compressor 1 is incorporated into a refrigeration cycle (not shown) and configured to compress a refrigerant gas G. The refrigerant gas G can be fluorocarbon, ammonia, or carbon dioxide, but is not particularly limited. The refrigeration cycle is composed of, for example, a primary refrigerant circuit and a secondary refrigerant circuit, and the reciprocating compressor 1 may be incorporated into the primary refrigerant circuit. As another example, the refrigeration cycle is composed of a high-speed refrigeration cycle and a low-speed refrigeration cycle, and the reciprocating compressor 1 may be incorporated into each of the cycles. In the following, the reciprocating compressor 1 is exemplified as a multi-cylinder reciprocating compressor having a plurality of pistons 36 and a plurality of cylinders 32, but the reciprocating compressor 1 of the present disclosure may be a single-cylinder reciprocating compressor.

[0018] The reciprocating compressor 1 includes a housing 22, which is provided with an intake port 24 and a discharge port 26 for the refrigerant gas G. Inside the housing 22 are an intake chamber 28 communicating with the intake port 24, a discharge chamber 30 communicating with the discharge port 26, a cylinder 32 equipped with an intake valve and a discharge valve, and a crank chamber 34 located below the cylinder 32. A piston 36 is arranged to reciprocate within the cylinder 32, and the compression chamber is partitioned by the inner wall surface of the cylinder 32 and the piston 36. The compression chamber can communicate with the intake chamber 28 via the intake valve and with the discharge chamber 30 via the discharge valve.

[0019] One end of the cylinder 32 communicates with the crankcase 34, and a connecting rod 10, connected to the piston 36 via a piston pin (not shown), extends into the crankcase 34. The crankcase 34 is located below the intake chamber 28, and the two chambers are separated from each other by a partition wall 29 that forms part of the housing 22. A crankshaft 40 is rotatably positioned inside the crankcase 34, and the connecting rod 10 is connected to the crankpin 41 of the crankshaft 40. More specifically, the crankshaft 40 is rotatably supported by the housing 22 via a sliding bearing acting as a radial bearing. A sliding bearing, also acting as a radial bearing, is interposed between the connecting rod 10 and the piston 36 and crankshaft 40.

[0020] One end of the crankshaft 40 airtightly penetrates the housing 22 and is connected to a drive source located on the outside of the housing 22. When the crankshaft 40 rotates due to the power supplied from the drive source, the piston 36 reciprocates within the cylinder 32. This causes the intake stroke, compression stroke, and discharge stroke of the refrigerant gas G to be executed repeatedly in sequence.

[0021] The reciprocating compressor 1 is configured to supply lubricating oil L to sliding parts such as radial bearings and pistons 36 during operation. Specifically, an oil storage chamber for lubricating oil L is formed at the bottom of the crank chamber 34. The reciprocating compressor 1 is equipped with an oil pump 42 that operates in conjunction with the crankshaft 40, and the lubricating oil L drawn up from the oil storage chamber by the oil pump 42 is supplied to each sliding part through oil passages provided inside or outside the housing 22. Oil passages are also formed inside the crankshaft 40, for example, as shown by dashed lines in Figure 1, and lubricating oil L can be supplied between the inner circumferential surface 17i of the metal bearing 17 (described later) and the outer circumferential surface 41o of the crankpin 41, and to the lubricating oil flow holes 16 formed in the connecting rod 10 (described later). In this embodiment, oil filters 46 and 48 for purifying the lubricating oil L are installed inside the oil storage chamber and outside the housing 22, respectively.

[0022] Figure 2 is an external view of the connecting rod 10 according to several embodiments of the reciprocating compressor 1. Figure 3 is a view of the vicinity of the big end of the connecting rod 10 according to several embodiments. Figure 4 is a view of the rod-side big end and upper metal according to one embodiment. Figure 5 is a view of the cap portion and lower metal according to one embodiment. Figure 6 is a view of the cap portion and lower metal according to another embodiment. Note that in Figure 3, the description of the connecting rod bolt 91 that connects the rod-side big end 11A and the cap portion 11B, which will be described later, is omitted.

[0023] In some embodiments, the connecting rod 10 comprises a large end 11 connected to the crank pin 41 of the crankshaft 40, a small end 13 connected to a piston pin (not shown), a rod portion 15 connecting the large end 11 and the small end 13, and a metal bearing 17 positioned between the crank pin 41 and the large end 11, which is split in half circumferentially around the crank pin 41.

[0024] In the following description, the circumferential direction centered on the crankpin 41, that is, the central axis AXc of the crankpin 41, will also be simply referred to as the circumferential direction. Similarly, in the following description, the radial direction centered on the central axis AXc of the crankpin 41 will also be simply referred to as the radial direction, and the axial direction centered on the central axis AXc of the crankpin 41 will also be simply referred to as the axial direction. Note that the radial direction centered on the central axis AXc of the crankpin 41 extends in the direction of the plane of the paper in each of Figures 2 to 6, and the axial direction centered on the central axis AXc of the crankpin 41 extends in the direction of the depth of the paper in each of Figures 2 to 6.

[0025] The large end portion 11 is circumferentially divided into a rod-side large end portion 11A connected to the rod portion 15 and a cap portion 11B connected to the rod-side large end portion 11A. For example, as shown in Figures 2 and 3, the division position Pc of the large end portion 11, that is, the division position Pc between the rod-side large end portion 11A and the cap portion 11B, is located circumferentially away from the plane PV that includes the central axis AXc of the crankpin 41 and is perpendicular to the extending direction of the rod portion 15 (the extending direction of the central axis AXr of the rod portion 15). This makes it possible to attach the connecting rod 10 to the crankpin 41 even if it is difficult to set the division position Pc of the large end portion 11 to the same position as the plane PV, for example, due to reasons such as ease of assembly when attaching the connecting rod 10 to the crankpin 41.

[0026] (Rod-side big end 11A) The rod-side big end 11A has two dividing surfaces Ps at the rod-side big end 11A with the cap portion 11B, which are two of the four dividing surfaces Ps formed at the dividing position Pc of the big end 11: a first dividing surface Ps1 on one side in the circumferential direction and a second dividing surface Ps2 on the other side in the circumferential direction. The first dividing surface Ps1 is formed closer to the rod portion 15 in the direction of extension of the rod portion 15, i.e., in the direction of extension of the central axis AXr of the rod portion 15, than the second dividing surface Ps2. In other words, the circumferential distance between the first dividing surface Ps1 along the bearing surface 11Aa of the rod-side big end 11A and the central axis AXr of the rod portion 15 is shorter than the circumferential distance between the second dividing surface Ps2 along the bearing surface 11Aa and the central axis AXr of the rod portion 15. In Figures 2 to 6, within the circumferential direction around the central axis AXc of the crankpin 41, the clockwise direction shown is considered one side, and the counterclockwise direction shown is considered the other side.

[0027] An upper metal 17A of a metal bearing 17, which will be described later, is positioned on the bearing surface 11Aa of the rod-side big end 11A. A pair of female threaded portions 11Ab are formed on the rod-side big end 11A, sandwiching the crankpin 41 when viewed from the axial direction. A lubricating oil flow hole 16 is formed in the rod-side big end 11A and the rod 15, extending along the direction of extension of the rod 15, penetrating both the rod-side big end 11A and the rod 15, and connecting the bearing surface 11Aa of the rod-side big end 11A with the inner circumferential surface 13a of the small end 13 (see Figure 2).

[0028] (Cap portion 11B) The cap portion 11B has two dividing surfaces Ps in the cap portion 11B that are the two dividing surfaces Ps with the rod-side big end portion 11A, out of the four dividing surfaces Ps formed at the dividing position Pc of the big end portion 11: a third dividing surface Ps3 on one side in the circumferential direction and a fourth dividing surface Ps4 on the other side in the circumferential direction. The lower metal 17B of the metal bearing 17, which will be described later, is arranged on the bearing surface 11Ba of the cap portion 11B.

[0029] The cap portion 11B has a pair of bolt holes 11Bb formed on either side of the crankpin 41 when viewed from the axial direction, through which the connecting rod bolt 91 is inserted. When the cap portion 11B is connected to the rod-side big end 11A by the connecting rod bolt 91, the third dividing surface Ps3 comes into contact with the second dividing surface Ps2 of the rod-side big end 11A, and the fourth dividing surface Ps4 comes into contact with the first dividing surface Ps1 of the rod-side big end 11A.

[0030] (Metal Bearing 17) The metal bearing 17 is divided into an upper metal 17A, in which the outer circumferential surface 17o of the metal bearing 17 in the central part of the circumferential direction is in contact with the bearing surface 11Aa of the rod-side big end 11A, and a lower metal 17B, in which the outer circumferential surface 17o of the metal bearing 17 in the central part of the circumferential direction is in contact with the bearing surface 11Ba of the cap portion 11B. The division position Pm of the metal bearing 17 is located in a plane PV that includes the central axis AXc of the crankpin 41 and is perpendicular to the extending direction of the rod portion 15. Note that the division position Pm of the metal bearing 17 may be located not in the plane PV, but within a range of 40 degrees or less in the circumferential direction to one side and the other side of the plane PV as a reference. This allows the split position Pm of the metal bearing 17 to be set at a circumferential position that avoids the region where the surface pressure is relatively high between the outer surface 41o of the crankpin 41 and the inner surface 17i of the metal bearing 17, thereby enabling good bearing performance. The region where the surface pressure is relatively high between the outer surface 41o of the crankpin 41 and the inner surface 17i of the metal bearing 17 is located in two regions that are relatively far from the aforementioned plane PV on one side and the other side in the extending direction of the rod portion 15, that is, in two regions that are relatively close to the two intersection points of the central axis AXr of the rod portion 15 and the inner surface 17i of the metal bearing 17.

[0031] In some embodiments of the connecting rod 10, as shown in Figures 3 and 4, when the first dividing surface Ps1 is closer to the rod portion 15 in the extending direction of the rod portion 15 than the second dividing surface Ps2, it is preferable that one of the two end faces 17s (end face 17s1, end face 17s2) of the upper metal 17A, end face 17s1, protrudes from the first dividing surface Ps1 to one side in the circumferential direction. In this case, the other end face 17s2 of the two end faces 17s (end face 17s1, end face 17s2) of the upper metal 17A is located to one side in the circumferential direction from the second dividing surface Ps2. In this case, as shown in Figures 3 and 5, one of the two end faces 17s (end face 17s3, end face 17s4) of the lower metal 17B, end face 17s3, protrudes to one side in the circumferential direction from the third dividing surface Ps3 of the cap portion 11B, and the other end face 17s4, in the circumferential direction, is located to one side in the circumferential direction from the fourth dividing surface Ps4.

[0032] As a result, one end face 17s1 on the circumferential direction of the upper metal 17A can be moved away from the region where the surface pressure is relatively high in the upper metal 17A, which is one of two regions where the surface pressure is relatively high in the area between the outer circumferential surface 41o of the crankpin 41 and the inner circumferential surface 17i of the metal bearing 17. Also, since the metal bearing 17 is split in half, as described above, one end face 17s3 on the circumferential direction of the lower metal 17B will protrude to one side in the circumferential direction from the third dividing surface Ps3 of the cap portion 11B. Therefore, one end face 17s3 on the circumferential direction of the lower metal 17B can be moved away from the region where the surface pressure is relatively high in the lower metal 17B, which is one of two regions where the surface pressure is relatively high in the area between the outer circumferential surface 41o of the crankpin 41 and the inner circumferential surface 17i of the metal bearing 17.

[0033] As described above, when the cap portion 11B is connected to the rod-side big end 11A by the connecting rod bolt 91, the third dividing surface Ps3 comes into contact with the second dividing surface Ps2, and the fourth dividing surface Ps4 comes into contact with the first dividing surface Ps1. In this state, the pair of circumferential end faces 17s of the upper metal 17A and the pair of circumferential end faces 17s of the lower metal 17B come into contact with each other, causing the upper metal 17A and the lower metal 17B to be slightly compressed from each other in the circumferential direction. As a result, when the cap portion 11B is connected to the rod-side big end 11A by the connecting rod bolt 91, the relative circumferential positions of the upper metal 17A and the lower metal 17B are positioned.

[0034] (First positioning structure 51) In the connecting rod 10 according to one embodiment shown in Figures 3 and 4, the upper metal 17A is positioned relative to the rod-side big end 11A. Specifically, for example, the connecting rod 10 according to one embodiment shown in Figures 3 and 4 includes a first positioning structure 51 that determines the position of the upper metal 17A relative to the rod-side big end 11A. That is, in the connecting rod 10 according to one embodiment shown in Figures 3 and 4, the first positioning structure 51 includes a fitting member 63 that fits between the rod-side big end 11A and the upper metal 17A, a first insertion hole 61 into which the fitting member 63 is inserted and which restricts the movement of the fitting member 63 at least in the circumferential direction relative to the rod-side big end 11A, and a second insertion hole 62 into which the fitting member 63 is inserted and which restricts the movement of the fitting member 63 at least in the circumferential direction relative to the upper metal 17A.

[0035] The first insertion hole 61 is a hole formed radially outward from the bearing surface 11Aa of the rod-side large end 11A, and in the example shown in Figures 3 and 4, it is a hole coaxial with the central axis AXr of the rod 15, which is also the central axis of the lubricating oil flow hole 16 in the circumferential direction. In the example shown in Figures 3 and 4, the inner diameter of the first insertion hole 61 is preferably larger than the inner diameter of the lubricating oil flow hole 16.

[0036] The second insertion hole 62 is a bottomed hole formed so as to be recessed radially inward from the outer circumferential surface 17o of the upper metal 17A, and is formed in a position coaxial with the first insertion hole 61 when the upper metal 17A is attached to the rod-side big end 11A. In the example shown in Figures 3 and 4, a through hole 62a is formed at the bottom of the second insertion hole 62, penetrating to the inner circumferential surface 17i of the upper metal 17A. The through hole 62a is formed in a position coaxial with the first insertion hole 61 when the upper metal 17A is attached to the rod-side big end 11A.

[0037] The fitting member 63 is a member having a cylindrical outer surface formed to fit into the first insertion hole 61 and the second insertion hole 62. The outer diameter of the outer surface of the fitting member 63 is equal to the inner diameter of the first insertion hole 61 and the second insertion hole 62 within a predetermined tolerance range. In the example shown in Figures 3 and 4, the fitting member 63 is a cylindrical member having a through hole 63a that penetrates the fitting member 63 radially. The through hole 63a is a communication hole that communicates with the lubricating oil flow hole 16. The radial insertion amount of the fitting member 63 into the upper metal 17A is smaller than the thickness of the upper metal 17A.

[0038] In some embodiments of the connecting rod 10, the fitting member 63 is fitted into the first insertion hole 61 and the second insertion hole 62, thereby preventing relative movement between the rod-side big end 11A and the fitting member 63 in the circumferential and axial directions, and preventing relative movement between the fitting member 63 and the upper metal 17A in the circumferential and axial directions. As a result, in some embodiments of the connecting rod 10, relative movement between the rod-side big end 11A and the upper metal 17A in the circumferential and axial directions is prevented. In one embodiment of the connecting rod 10 shown in Figures 3 and 4, the lubricating oil flow hole 16, the through hole 63a of the fitting member 63, and the through hole 62a of the upper metal 17A are in communication. This allows lubricating oil L from the oil passage formed inside the crankshaft 40 to be supplied to the lubricating oil flow hole 16.

[0039] In some embodiments of the connecting rod 10, the first insertion hole 61, the second insertion hole 62, and the fitting member 63 may be provided in positions that do not overlap with the lubricating oil flow hole 16 in the circumferential direction. In this case, the through hole 63a of the fitting member 63 does not need to be provided. When the first insertion hole 61, the second insertion hole 62, and the fitting member 63 are provided in positions that do not overlap with the lubricating oil flow hole 16 in the circumferential direction, a through hole is provided that penetrates the upper metal 17A radially and communicates with the lubricating oil flow hole 16. This allows lubricating oil L from the oil passage formed inside the crankshaft 40 to be supplied to the lubricating oil flow hole 16.

[0040] In the connecting rod 10 according to one embodiment shown in Figure 5, there is no positioning structure to restrict the relative movement of the cap portion 11B and the lower metal 17B in the circumferential direction. However, it is preferable to have a positioning structure that restricts the relative movement of the cap portion 11B and the lower metal 17B in the axial direction, which is different from the second positioning structure 52 described later.

[0041] (Second positioning structure 52) In the connecting rod 10 according to another embodiment shown in Figure 6, the lower metal 17B is positioned relative to the cap portion 11B. Specifically, for example, the connecting rod 10 according to another embodiment shown in Figure 6 includes a second positioning structure 52 that determines the position of the lower metal 17B relative to the cap portion 11B. That is, in the connecting rod 10 according to another embodiment shown in Figure 6, the second positioning structure 52 includes a fitting member 68 that fits into the cap portion 11B and the lower metal 17B, a first insertion hole 66 into which the fitting member 68 is inserted and which restricts the movement of the fitting member 68 at least in the circumferential direction relative to the cap portion 11B, and a second insertion hole 67 into which the fitting member 68 is inserted and which restricts the movement of the fitting member 68 at least in the circumferential direction relative to the lower metal 17B.

[0042] The first insertion hole 66 is a hole formed radially outward from the bearing surface 11Ba of the cap portion 11B.

[0043] The second insertion hole 67 is a bottomed hole formed so as to be recessed radially inward from the outer peripheral surface 17o of the lower metal 17B, and is formed at a position coaxial with the first insertion hole 66 when the lower metal 17B is attached to the cap portion 11B.

[0044] The fitting member 68 is a member having a cylindrical outer peripheral surface formed so as to be fitted into the first insertion hole 66 and the second insertion hole 67. The outer diameter of the outer peripheral surface of the fitting member 68 is equal to the inner diameters of the first insertion hole 66 and the second insertion hole 67 within a predetermined tolerance range. Note that the radial insertion amount of the fitting member 68 into the lower metal 17B is smaller than the thickness of the lower metal 17B.

[0045] In the connecting rod 10 according to another embodiment, when the fitting member 68 is fitted into the first insertion hole 66 and the second insertion hole 67, relative movement in the circumferential direction and the axial direction between the cap portion 11B and the fitting member 68 is prohibited, and relative movement in the circumferential direction and the axial direction between the fitting member 68 and the lower metal 17B is prohibited. Thereby, in the connecting rod 10 according to another embodiment, relative movement in the circumferential direction and the axial direction between the cap portion 11B and the lower metal 17B is prohibited.

[0046] In the connecting rod 10 according to another embodiment, the first insertion hole 66, the second insertion hole 67, and the fitting member 68 are provided at positions overlapping with the central axis AXr of the rod portion 15 in the circumferential direction, but may be provided at positions not overlapping with the central axis AXr of the rod portion 15.

[0047] When the connecting rod 10 includes the second positioning structure 52, it may not include the first positioning structure 51, but it is preferable that a positioning structure for restricting relative movement in the axial direction between the large end portion 11A on the rod portion side and the upper metal 17A, which is different from the first positioning structure 51, is provided.

[0048] Incidentally, the connecting rod 10 may include a first positioning structure 51 and a second positioning structure 52. In this case, it is preferable that relative circumferential movement between the large end portion 11A on the rod portion side and the upper metal 17A is possible to some extent in the first positioning structure 51, or that relative circumferential movement between the cap portion 11B and the lower metal 17B is possible to some extent in the second positioning structure 52.

[0049] (Regarding the positioning of the large end portion 11A on the rod portion side and the cap portion 11B) As described above, when the cap portion 11B is connected to the large end portion 11A on the rod portion side by the connecting rod bolt 91, the relative circumferential position between the upper metal 17A and the lower metal 17B is positioned. In the connecting rod 10 according to some embodiments, in the circumferential direction, the division position Pc of the large end portion 11 and the division position Pm of the metal bearing 17 are different. Therefore, the outer peripheral surface 17o of either one of the one side or the other side in the circumferential direction of the upper metal 17A contacts the bearing surface 11Ba of the cap portion 11B, and the outer peripheral surface 17o of either one of the one side or the other side in the circumferential direction of the lower metal 17B contacts the bearing surface 11Aa of the large end portion 11A on the rod portion side. In the example shown in FIGS. 2 to 6, the outer peripheral surface 17o of the one side end portion in the circumferential direction of the upper metal 17A contacts the bearing surface 11Ba of the cap portion 11B, and the outer peripheral surface 17o of the one side end portion in the circumferential direction of the lower metal 17B contacts the bearing surface 11Aa of the large end portion 11A on the rod portion side. Thereby, the radial position of the cap portion 11B with respect to the large end portion 11A on the rod portion side can be positioned via the upper metal 17A and the lower metal 17B.

[0050] Therefore, when the upper metal 17A is positioned relative to the rod-side big end 11A by the first positioning structure 51, and the cap portion 11B is connected to the rod-side big end 11A by the connecting rod bolt 91, the lower metal 17B is positioned relative to the upper metal 17A in the circumferential and radial directions, and the cap portion 11B is positioned radially relative to both the upper metal 17A and the lower metal 17B. As a result, the radial relative position of the rod-side big end 11A and the cap portion 11B is positioned by the first positioning structure 51. The circumferential relative position of the rod-side big end 11A and the cap portion 11B is positioned when the third dividing surface Ps3 abuts against the second dividing surface Ps2 and the fourth dividing surface Ps4 abuts against the first dividing surface Ps1.

[0051] Furthermore, when the lower metal 17B is positioned relative to the cap portion 11B by the second positioning structure 52, and the cap portion 11B is connected to the rod-side big end 11A by the connecting rod bolt 91, the upper metal 17A is positioned relative to the lower metal 17B in the circumferential and radial directions, and the rod-side big end 11A is positioned radially relative to the upper metal 17A and the lower metal 17B. As a result, the radial relative position of the rod-side big end 11A and the cap portion 11B is positioned by the second positioning structure 52. The circumferential relative position of the rod-side big end 11A and the cap portion 11B is positioned when the third dividing surface Ps3 abuts against the second dividing surface Ps2 and the fourth dividing surface Ps4 abuts against the first dividing surface Ps1.

[0052] Furthermore, looking at the connecting rod 10 according to several embodiments from a different perspective than those described above, it can be said that the cap portion 11B is positioned relative to the rod-side big end 11A as follows. That is, in the connecting rod 10 according to several embodiments, the upper metal 17A and the lower metal 17B are positioned by the contact of their respective circumferential end faces 17s. The rod-side big end 11A and the upper metal 17A and lower metal 17B are positioned by the radial contact between the rod-side big end 11A and the upper metal 17A and lower metal 17B. The cap portion 11B and the upper metal 17A and lower metal 17B are positioned radially by the cap portion 11B contacting the upper metal 17A and lower metal 17B in the radial direction.

[0053] Therefore, according to the connecting rod 10 according to some embodiments, the cap portion 11B can be positioned relatively easily relative to the rod-side big end portion 11A by the upper metal 17A and the lower metal 17B. Furthermore, according to the connecting rod 10 according to some embodiments, the need for other configurations to position the cap portion 11B relative to the rod-side big end portion 11A is reduced, thus simplifying the configuration for positioning the cap portion 11B relative to the rod-side big end portion 11A.

[0054] As an example of a reciprocating fluid machine according to several embodiments, the reciprocating compressor 1 comprises a crankshaft 40 and a connecting rod 10 having the above-described configuration, which has a large end 11 connected to a crankpin 41. This simplifies the configuration for positioning the cap portion 11B relative to the rod-side large end 11A, improving the ease of assembly of the reciprocating fluid machine. Furthermore, according to the reciprocating compressor 1 as an example of a reciprocating fluid machine according to several embodiments, the manufacturing cost of the reciprocating fluid machine can be reduced.

[0055] In some embodiments of the connecting rod 10, when the upper metal 17A is positioned relative to the rod-side big end 11A, that is, when the connecting rod 10 is equipped with a first positioning structure 51, the circumferential position of the upper metal 17A is positioned relative to the rod-side big end 11A, and the circumferential position of the lower metal 17B is positioned relative to the upper metal 17A. The position of the cap portion 11B is then positioned relative to the upper metal 17A and the lower metal 17B. As a result, the radial position of the cap portion 11B can be positioned relative to the rod-side big end 11A by the upper metal 17A and the lower metal 17B, thus simplifying the configuration for positioning the cap portion 11B relative to the rod-side big end 11A.

[0056] In some embodiments of the connecting rod 10, a first positioning structure 51 is provided between the rod-side big end 11A and the upper metal 17A, so that the upper metal 17A can be positioned relative to the rod-side big end 11A. Since the first positioning structure 51 includes a fitting member 63 that fits into the rod-side big end 11A and the upper metal 17A, the upper metal 17A can be positioned relative to the rod-side big end 11A with a relatively simple configuration.

[0057] In some embodiments of the connecting rod 10, the rod-side large end 11A has a lubricating oil flow hole 16 and a first insertion hole 61, the upper metal 17A has a second insertion hole 62, and the fitting member 63 has a through hole 63a which is a communication hole that communicates with the lubricating oil flow hole 16. This allows lubricating oil L to be supplied to the lubricating oil flow hole 16 through the through hole 63a of the fitting member 63. Furthermore, according to some embodiments of the connecting rod 10, the fitting member 63 can be fitted to the rod-side large end 11A by utilizing the lubricating oil flow hole 16 or by slight processing of the end of the lubricating oil flow hole 16 on the large end 11 side.

[0058] In some embodiments of the connecting rod 10, a second positioning structure 52 is provided between the cap portion 11B and the lower metal 17B, so that the lower metal 17B can be positioned relative to the cap portion 11B.

[0059] This disclosure is not limited to the embodiments described above, and also includes modified forms of the embodiments described above, as well as forms that combine these forms as appropriate. For example, in the connecting rod 10 according to some of the embodiments described above, if the division position Pc of the large end 11 and the division position Pm of the metal bearing 17 are different in the circumferential direction, the division position Pc of the large end 11 may be located within the plane PV described above, and the division position Pm of the metal bearing 17 may be located outside the plane PV described above.

[0060] In the above description, the reciprocating compressor 1 was described as an example of a reciprocating fluid machine, but the connecting rod 10 described above can also be applied to connecting rods in other reciprocating fluid machines such as reciprocating engines.

[0061] The contents of each of the above embodiments can be understood, for example, as follows: (1) A connecting rod 10 of a reciprocating fluid machine according to at least one embodiment of the present disclosure comprises a large end 11 that is connected to a crank pin 41 of a crankshaft 40 and is divided in the circumferential direction around the crank pin 41, and a metal bearing 17 that is disposed between the crank pin 41 and the large end 11 and is divided in half in the circumferential direction. The large end 11 is divided into a rod-side large end 11A connected to a rod-side large end 15 and a cap portion 11B connected to the rod-side large end 11A. The metal bearing 17 is divided into an upper metal 17A whose circumferential central portion is in contact with the bearing surface 11Aa of the rod-side large end 11A, and a lower metal 17B whose circumferential central portion is in contact with the bearing surface 11Ba of the cap portion 11B. In the circumferential direction, the division position Pc of the large end 11 and the division position Pm of the metal bearing 17 are different. When the upper metal 17A is positioned relative to the rod-side large end 11A, the lower metal 17B is positioned relative to the upper metal 17A, and the cap portion 11B is positioned relative to both the upper metal 17A and the lower metal 17B. When the lower metal 17B is positioned relative to the cap portion 11B, the upper metal 17A is positioned relative to the lower metal 17B, and the rod-side large end 11A is positioned relative to both the upper metal 17A and the lower metal 17B.

[0062] According to the configuration of (1) above, the cap portion 11B can be positioned relatively easily relative to the rod-side big end portion 11A by the upper metal 17A and the lower metal 17B. Furthermore, according to the configuration of (1) above, the need for other configurations for positioning the cap portion 11B relative to the rod-side big end portion 11A is reduced, so the configuration for positioning the cap portion 11B relative to the rod-side big end portion 11A can be simplified.

[0063] (2) In some embodiments, in the configuration of (1) above, if the upper metal 17A is positioned relative to the rod-side big end 11A, the circumferential position of the upper metal 17A is preferably positioned relative to the rod-side big end 11A, and the circumferential position of the lower metal 17B is preferably positioned relative to the upper metal 17A. The radial position of the cap portion 11B with respect to the crankpin 41 is preferably positioned relative to the upper metal 17A and the lower metal 17B.

[0064] According to the configuration of (2) above, the upper metal 17A and the lower metal 17B can position the radial position of the cap portion 11B relative to the rod-side big end 11A, thus simplifying the configuration for positioning the cap portion 11B relative to the rod-side big end 11A.

[0065] (3) In some embodiments, in the configuration of (1) or (2) above, the division position Pc of the large end 11 may be located at a position circumferentially away from the plane PV that includes the central axis AXc of the crankpin 41 and is perpendicular to the extending direction of the rod portion 15.

[0066] According to the configuration of (3) above, even if it is difficult to set the division position Pc of the big end 11 to the same position as the plane PV due to reasons such as ease of assembly when attaching the connecting rod 10 to the crank pin 41, the connecting rod 10 can be attached to the crank pin 41.

[0067] (4) In some embodiments, in the configuration of (1) or (2) above, the division position Pm of the metal bearing 17 may be located within a range of 40 degrees or less in the circumferential direction to one side and the other side of the plane PV that includes the central axis AXc of the crankpin 41 and is perpendicular to the extending direction of the rod portion 15.

[0068] According to the configuration described in (4) above, the division position Pm of the metal bearing 17 can be set at a circumferential position that avoids the region where the surface pressure is relatively high between the outer circumferential surface 41o of the crankpin 41 and the inner circumferential surface 17i of the metal bearing 17, thereby enabling good bearing performance.

[0069] (5) In some embodiments, in the configuration of (4) above, of the two dividing surfaces Ps between the rod portion side large end 11A and the cap portion 11B, the first dividing surface Ps1 on one side in the circumferential direction is preferable to be closer to the rod portion 15 in the extending direction of the rod portion 15 than the second dividing surface Ps2 on the other side in the circumferential direction. The end (end face 17s1) on one side in the circumferential direction of the upper metal 17A is preferable to protrude from the first dividing surface Ps1 to one side in the circumferential direction.

[0070] According to the configuration of (5) above, of the two regions where the surface pressure is relatively high between the outer surface 41o of the crankpin 41 and the inner surface 17i of the metal bearing 17, the upper metal 17A can be positioned away from the region where the surface pressure is relatively high, with respect to one end (end face 17s1) of the upper metal 17A in the circumferential direction. Furthermore, since the metal bearing 17 is split in half, the lower metal 17B's end (end face 17s3) in the circumferential direction protrudes from one of the two dividing surfaces (third dividing surface Ps3, fourth dividing surface Ps4) between the cap portion 11B and the rod-side large end 11A, with the dividing surface Ps (third dividing surface Ps3) being the one furthest from the rod portion 15 in the extending direction of the rod portion 15. Therefore, in the case of the lower metal 17B, one end (end face 17s3) in the circumferential direction of the lower metal 17B can be moved away from the region where the surface pressure is relatively high, which is one of the two regions between the outer circumferential surface 41o of the crankpin 41 and the inner circumferential surface 17i of the metal bearing 17.

[0071] (6) In some embodiments, in the configuration of (5) above, the outer circumferential surface 17o of one end of the upper metal 17A in the circumferential direction may be in contact with the bearing surface 11Ba of the cap portion 11B. The outer circumferential surface 17o of one end of the lower metal 17B in the circumferential direction may be in contact with the bearing surface 11Aa of the rod portion side large end 11A.

[0072] According to the configuration of (6) above, the outer peripheral surface 17o of one end of the upper metal 17A in the circumferential direction contacts the bearing surface 11Ba of the cap portion 11B, and the outer peripheral surface 17o of one end of the lower metal 17B in the circumferential direction contacts the bearing surface 11Aa of the rod-side big end 11A. Therefore, the radial position of the cap portion 11B with respect to the rod-side big end 11A can be positioned via the upper metal 17A and the lower metal 17B.

[0073] (7) In some embodiments, if the upper metal 17A is positioned relative to the rod-side big end 11A in any of the configurations (1) to (6) above, a first positioning structure 51 for determining the position of the upper metal 17A relative to the rod-side big end 11A is provided.

[0074] According to the configuration of (7) above, the upper metal 17A can be positioned relative to the rod-side big end 11A.

[0075] (8) In some embodiments, in the configuration of (7) above, the first positioning structure 51 may include a fitting member 63 that fits with the rod-side large end 11A and the upper metal 17A.

[0076] According to the configuration of (8) above, the upper metal 17A can be positioned relative to the rod-side big end 11A with a relatively simple configuration.

[0077] (9) In some embodiments, in the configuration of (8) above, the rod-side big end 11A may have a lubricating oil flow hole 16 that penetrates the rod 15 along the extending direction of the rod 15, and a first insertion hole 61 that restricts the movement of the fitting member 63 at least in the circumferential direction relative to the rod-side big end 11A and into which the fitting member 63 is inserted. The upper metal 17A may have a second insertion hole 62 that restricts the movement of the fitting member 63 at least in the circumferential direction relative to the upper metal 17A and into which the fitting member 63 is inserted. The fitting member 63 may have a communication hole (through hole 63a) that communicates with the lubricating oil flow hole 16.

[0078] According to the configuration of (9) above, lubricating oil L can be supplied to the lubricating oil flow hole 16 through the communication hole (through hole 63a) of the fitting member 63. Furthermore, according to the configuration of (9) above, the fitting member 63 can be fitted to the rod-side big end 11A by utilizing the lubricating oil flow hole 16, or by slightly machining the end of the lubricating oil flow hole 16 on the big end 11 side.

[0079] (10) In some embodiments, if the lower metal 17B is positioned relative to the cap portion 11B in any of the configurations (1) to (9) above, a second positioning structure 52 for determining the position of the lower metal 17B relative to the cap portion 11B may be provided.

[0080] According to the configuration of (10) above, the lower metal 17B can be positioned relative to the cap portion 11B.

[0081] (11) A connecting rod 10 of a reciprocating fluid machine according to at least one embodiment of the present disclosure comprises a large end 11 that is connected to a crankpin 41 of a crankshaft 40 and is divided circumferentially around the crankpin 41, and a metal bearing 17 that is disposed between the crankpin 41 and the large end 11 and is divided in half circumferentially. The large end 11 is divided into a rod-side large end 11A connected to a rod-side large end 15 and a cap portion 11B connected to the rod-side large end 11A. The metal bearing 17 is divided into an upper metal 17A whose circumferential central portion is in contact with the bearing surface 11Aa of the rod-side large end 11A, and a lower metal 17B whose circumferential central portion is in contact with the bearing surface 11Ba of the cap portion 11B. In the circumferential direction, the division position Pc of the large end 11 and the division position Pm of the metal bearing 17 are different. The upper metal 17A and the lower metal 17B are positioned relative to each other in the circumferential direction by contacting each other's circumferential end faces 17s. The rod-side big end 11A and the upper metal 17A and lower metal 17B are positioned relative to each other in the radial direction centered on the crankpin 41 by contacting the rod-side big end 11A with the upper metal 17A and lower metal 17B. The cap portion 11B and the upper metal 17A and lower metal 17B are positioned relative to each other in the radial direction by contacting the cap portion 11B with the upper metal 17A and lower metal 17B.

[0082] According to the configuration of (11) above, the cap portion 11B can be positioned relatively easily relative to the rod-side big end portion 11A by the upper metal 17A and the lower metal 17B. Furthermore, according to the configuration of (13) above, the need for other configurations to position the cap portion 11B relative to the rod-side big end portion 11A is reduced, thus simplifying the configuration for positioning the cap portion 11B relative to the rod-side big end portion 11A.

[0083] (12) A reciprocating fluid machine according to at least one embodiment of the present disclosure comprises a crankshaft 40 and a connecting rod 10 having any of the configurations (1) to (11) above, the connecting rod having a large end 11 connected to a crankpin 41.

[0084] According to the configuration of (12) above, the configuration for positioning the cap portion 11B relative to the rod-side big end portion 11A can be simplified, thereby improving the ease of assembly of the reciprocating fluid machine. Furthermore, according to the configuration of (12) above, the manufacturing cost of the reciprocating fluid machine can be reduced.

[0085] (13) In some embodiments, in the configuration of (12) above, the reciprocating fluid machine may be a compressor (reciprocating compressor 1) for compressing the fluid.

[0086] The configuration described in (13) above improves the ease of assembly of the reciprocating compressor. Furthermore, the configuration described in (13) above reduces the manufacturing cost of the reciprocating compressor (reciprocating compressor 1).

[0087] 1 Reciprocating compressor 10 Connecting rod 11 Big end 11A Rod-side big end 11Aa Bearing surface 11Ab Female thread portion 11B Cap portion 11Ba Bearing surface 13 Small end 15 Rod portion 16 Lubrication oil flow hole 17 Metal bearing 17A Upper metal 17B Lower metal 17i Inner circumferential surface 17o Outer circumferential surface 17s End face 17s1 End face 17s2 End face 17s3 End face 17s4 End face 36 Piston 40 Crankshaft 41 Crankpin 41o Outer circumferential surface 51 First positioning structure 52 Second positioning structure 61 First insertion hole 62 Second insertion hole 62a Through hole 63 Fitting member 63a Through hole 66 First insertion hole 67 Second insertion hole 68 Fitting member

Claims

1. A connecting rod for a reciprocating fluid machine, comprising: a large end portion divided circumferentially around the crankpin and connected to the crankpin of a crankshaft; a metal bearing disposed between the crankpin and the large end portion and divided in half circumferentially, wherein the large end portion is divided into a rod-side large end portion connected to a rod portion and a cap portion connected to the rod-side large end portion; the metal bearing is divided into an upper metal portion whose circumferential central portion is in contact with the bearing surface of the rod-side large end portion and a lower metal portion whose circumferential central portion is in contact with the bearing surface of the cap portion; the division position of the large end portion and the division position of the metal bearing are different in the circumferential direction; when the upper metal portion is positioned relative to the rod-side large end portion, the lower metal portion is positioned relative to the upper metal portion; the cap portion is positioned relative to the upper metal portion and the lower metal portion; when the lower metal portion is positioned relative to the cap portion, A connecting rod for a reciprocating fluid machine, wherein the upper metal is positioned relative to the lower metal, and the rod-side large end is positioned relative to the upper metal and the lower metal.

2. The connecting rod for a reciprocating fluid machine according to claim 1, wherein, when the upper metal is positioned with respect to the rod-side big end, the circumferential position of the upper metal is positioned with respect to the rod-side big end, the circumferential position of the lower metal is positioned with respect to the upper metal, and the radial position of the cap portion with respect to the crankpin is positioned with respect to the upper metal and the lower metal.

3. The connecting rod for a reciprocating fluid machine according to claim 1 or 2, wherein the division position of the large end is located at a position away in the circumferential direction from a plane that includes the central axis of the crankpin and is perpendicular to the extending direction of the rod portion.

4. The connecting rod of a reciprocating fluid machine according to claim 1 or 2, wherein the division position of the metal bearing is located within a range of 40 degrees or less in the circumferential direction, with respect to a plane that includes the central axis of the crankpin and is perpendicular to the extending direction of the rod portion, on each of the circumferential sides.

5. The connecting rod for a reciprocating fluid machine according to claim 4, wherein, of the two dividing surfaces with the cap portion at the large end on the rod side, the first dividing surface on one side in the circumferential direction is closer to the rod in the extending direction of the rod than the second dividing surface on the other side in the circumferential direction, and the end on one side in the circumferential direction of the upper metal protrudes from the first dividing surface to the one side in the circumferential direction.

6. The connecting rod for a reciprocating fluid machine according to claim 5, wherein the outer circumferential surface of one end of the upper metal in the circumferential direction is in contact with the bearing surface of the cap portion, and the outer circumferential surface of one end of the lower metal in the circumferential direction is in contact with the bearing surface of the large end on the rod portion side.

7. When the upper metal is positioned relative to the rod-side big end, the connecting rod of a reciprocating fluid machine according to claim 1 or 2, further comprising a first positioning structure for determining the position of the upper metal relative to the rod-side big end.

8. The connecting rod for a reciprocating fluid machine according to claim 7, wherein the first positioning structure includes a fitting member that fits with the rod-side big end and the upper metal.

9. The connecting rod for a reciprocating fluid machine according to claim 8, wherein the rod-side big end has a lubricating oil flow hole that penetrates the rod along the extending direction of the rod, and a first insertion hole that restricts the movement of the fitting member at least in the circumferential direction relative to the rod-side big end and into which the fitting member is inserted, the upper metal has a second insertion hole that restricts the movement of the fitting member at least in the circumferential direction relative to the upper metal and into which the fitting member is inserted, and the fitting member has a communication hole that communicates with the lubricating oil flow hole.

10. The connecting rod for a reciprocating fluid machine according to claim 1 or 2, further comprising a second positioning structure for determining the position of the lower metal relative to the cap portion when the lower metal is positioned relative to the cap portion.

11. A connecting rod for a reciprocating fluid machine, comprising: a large end portion divided circumferentially around the crankpin and connected to the crankpin of a crankshaft; and a metal bearing disposed between the crankpin and the large end portion and divided in half circumferentially, wherein the large end portion is divided into a rod-side large end portion connected to a rod portion and a cap portion connected to the rod-side large end portion; the metal bearing is divided into an upper metal portion whose circumferential central portion is in contact with the bearing surface of the rod-side large end portion and a lower metal portion whose circumferential central portion is in contact with the bearing surface of the cap portion; the division position of the large end portion and the division position of the metal bearing are different in the circumferential direction; and the relative circumferential position of the upper metal portion and the lower metal portion is positioned by the contact of their respective circumferential end faces. A connecting rod for a reciprocating fluid machine, wherein the rod-side big end and the upper metal and the lower metal are positioned such that the rod-side big end contacts the upper metal and the lower metal in the radial direction centered on the crankpin, and the cap portion and the upper metal and the lower metal are positioned such that the cap portion contacts the upper metal and the lower metal in the radial direction, thereby positioning the relative radial positions of the cap portion and the upper metal and the lower metal.

12. A reciprocating fluid machine comprising: the crankshaft; and the connecting rod according to any one of claims 1, 2, or 11, having the large end connected to the crankpin.

13. The reciprocating fluid machine according to claim 12, wherein the reciprocating fluid machine is a compressor for compressing a fluid.

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