Sliding bearing

Abstract

This sliding bearing has a sliding surface on which a rotating shaft slides, and allows a lubricating oil to enter a gap between the rotating shaft and the sliding surface. The sliding bearing includes: a first region provided with a plurality of grooves that are recessed in the sliding surface and extend from an end portion in an axial direction of the rotating shaft toward a center portion in the axial direction while being inclined along a rotational direction of the rotating shaft; and a second region having a sliding surface with a shape different from that of the first region. The first region is provided at both ends of the sliding surface in the rotational direction, and the second region is provided between the first regions.

Description

Plain bearings

[0001] The present disclosure relates to a plain bearing.

[0002] Conventionally, a sliding bearing having a groove on a sliding surface has been known (see, for example, Patent Document 1). The sliding bearing of Patent Document 1 has a groove that is inclined from the end portion to the center portion of the sliding surface along the rotation direction of the rotating shaft.

[0003] Japanese Patent Application Publication No. 2013-253650

[0004] The sliding bearing of Patent Document 1 has grooves for retaining lubricating oil that flows between the rotating shaft and the sliding surface. In addition to retaining lubricating oil, the sliding bearing must also be able to withstand the load from the rotating shaft.

[0005] An object of the present disclosure is to provide a sliding bearing that can simultaneously function to retain lubricating oil and to receive a load from a rotating shaft.

[0006] The sliding bearing according to the present disclosure has a sliding surface along which a rotating shaft slides, and lubricating oil enters the gap between the rotating shaft and the sliding surface, and comprises: a first region recessed in the sliding surface and provided with a plurality of grooves extending from the axial end side of the rotating shaft toward the center side in the axial direction while inclining along the rotation direction of the rotating shaft; and a second region having the sliding surface of a different shape from the first region, the first regions being provided at both ends of the sliding surface in the rotation direction, and the second region being provided between the first regions.

[0007] According to the sliding bearing of the present disclosure, the first region can achieve the function of retaining lubricating oil, and the second region can achieve the function of bearing the load from the rotating shaft, thereby making it possible to provide a sliding bearing that can simultaneously retain lubricating oil and bear the load from the rotating shaft.

[0008] 1 is a diagram showing an example in which a plain bearing according to an embodiment of the present disclosure is provided between a crankshaft and a cylinder block; 2 is a diagram showing an example in which a plain bearing according to an embodiment of the present disclosure is provided between a crankshaft and a connecting rod; 3 is a developed view showing a sliding surface of a first plain bearing according to an embodiment of the present disclosure; 4 is a developed view showing a sliding surface of a second plain bearing according to an embodiment of the present disclosure; 5 is an enlarged view of a groove according to an embodiment of the present disclosure;

[0009] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings.

[0010] As shown in Figure 1, the plain bearing 1 of this embodiment is used as a bearing member that rotatably supports a crankshaft (an example of a rotating shaft) 2 of an internal combustion engine on a cylinder block 4. The crankshaft 2 is rotatably supported while being sandwiched between a shaft bearing 4a provided in the cylinder block 4 and a shaft bearing 4c provided in a crank cap 4b. In this embodiment, the crank cap 4b is fixed to the bottom of the cylinder block 4 with bolts 4d.

[0011] In the following specification and drawings, the direction in which the crankshaft 2 extends will be referred to as the axial direction AX, and the direction in which the crankshaft 2 rotates will be referred to as the rotational direction RS.

[0012] The plain bearing 1 has a first plain bearing 1L provided on one radial side of the crankshaft 2, and a second plain bearing 1U provided opposite the first plain bearing 1L. The first plain bearing 1L and the second plain bearing 1U are each formed in a semi-cylindrical shape. A front end 8a (upstream side in the rotational direction RS) and a rear end 8b (downstream side in the rotational direction RS) (see FIG. 3) of the first plain bearing 1L in the rotational direction are respectively arranged to overlap a rear end 10b and a front end 10a (see FIG. 4) of the second plain bearing 1U in the rotational direction RS. The first plain bearing 1L and the second plain bearing 1U are overlapped in this manner to form a cylindrical shape.

[0013] In this embodiment, the first plain bearing 1L is disposed on the crank cap 4b side and is provided between the crankshaft 2 and the crank cap 4b. The second plain bearing 1U is provided on the cylinder block 4 side and is provided between the crankshaft 2 and the cylinder block 4.

[0014] 2, the plain bearing 1 may be used as a bearing member that rotatably supports a connecting rod 6 on a crankshaft 2. In this case, the first plain bearing 1L may be arranged on the connecting rod cap 6a side and provided between the crankshaft 2 and the connecting rod cap 6a. The second plain bearing 1U is provided on the connecting rod 6 side and provided between the crankshaft 2 and the connecting rod 6.

[0015] The plain bearing 1 is made of a metal material such as aluminum or copper. As shown in Fig. 1, the plain bearing 1 has a sliding surface 12 on which a crankshaft 2 slides. The plain bearing 1 may use a metal material such as aluminum or copper for the sliding surface 12 as is, or the sliding surface 12 may be coated with a resin.

[0016] Lubricating oil is supplied to the sliding surface 12. The lubricating oil is supplied to an oil hole 22 (see FIG. 4) provided in the second sliding bearing 1U via a lubrication passage (not shown) provided in the cylinder block 4.

[0017] A small gap is provided between the sliding surface 12 and the crankshaft 2. Specifically, the diameter of the cylindrical shape formed by the first sliding bearing 1L and the second sliding bearing 1U is set to be slightly larger than the journal diameter of the crankshaft 2. This allows lubricating oil to enter the gap between the crankshaft 2 and the sliding surface 12.

[0018] As shown in FIGS. 3 and 4 , the plain bearing 1 includes a first region 14 and a second region 16 .

[0019] The first regions 14 are provided at both ends of the sliding surface 12 in the rotation direction RS. The second regions 16 are provided between the first regions 14 provided at both ends. In this embodiment, the sliding bearing 1 includes the first region 14 and the second region 16 in each of the first sliding bearing 1L and the second sliding bearing 1U.

[0020] Specifically, as shown in Fig. 3, a lower front first region 14LF is provided on the front end 8a side of the first plain bearing 1L. A lower rear first region 14LR is provided on the rear end 8b side of the first plain bearing 1L. The lower second region 16L of the first plain bearing 1L is provided between the lower front first region 14LF and the lower rear first region LR. That is, the first plain bearing 1L is provided with the lower front first region 14LF, the lower second region 16L, and the lower rear first region LR in this order along the direction of rotation RS.

[0021] As shown in Figure 4, an upper front first region 14UF is provided on the front end 10a side of the second plain bearing 1U. An upper rear first region 14UR is provided on the rear end 10b side of the second plain bearing 1U. The upper second region 16U of the second plain bearing 1U is provided between the upper front first region 14UF and the upper rear first region UR. In other words, the second plain bearing 1U is provided with the upper front first region 14UF, upper second region 16U, and upper rear first region UR in this order along the direction of rotation RS.

[0022] 3 and 4, the first region 14 is provided with a plurality of grooves 18 that are recessed in the slide surface 12 and extend from an end side in the axial direction AX of the crankshaft 2 toward a central portion in the axial direction AX while inclining along the rotational direction RS of the crankshaft 2. As shown in Fig. 3, in the present embodiment, a pair of grooves 18 are recessed in the lower slide surface 12L and are provided in each of the lower front first region 14LF and the lower rear first region 14LR, extending from an end side 8c in the axial direction AX toward the central portion 8d while inclining along the rotational direction RS.

[0023] As shown in Figure 4, the second plain bearing 1U, like the first plain bearing 1L, is recessed in the upper sliding surface 12U, and a pair of grooves 18 are provided in each of the upper front first region 14UF and the upper rear first region 14UR, extending from the end portion 10c in the axial direction AX toward the central portion 10d while inclining along the rotational direction RS. Note that the second plain bearing 1U of this embodiment is provided with an oil supply passage 26 recessed in the upper sliding surface 12U at the central portion 10d in the axial direction AX, extending along the rotational direction RS. The oil hole 22 is provided within the oil supply passage 26.

[0024] As shown in Figure 5, the multiple grooves 18 are composed of three types of grooves: multiple first grooves 18a, multiple second grooves 18b, and multiple third grooves 18c. In this embodiment, the grooves 18 are formed by cutting the slideway surface 12 with a laser. The grooves 18 are extremely thin grooves, for example, with a width of about 0.1 mm to 1 mm and a depth of about 0.1 mm to 0.5 mm. However, the groove width and depth are not limited to these and can be changed as appropriate depending on the size (area) of the slideway surface 12.

[0025] The first groove portion 18a has an end side in the axial direction AX that opens toward the outer region X1 in the axial direction AX of the slide surface 12. Specifically, in the first slide bearing 1L, the axial direction AX end 8c of the first groove portion 18a is located at the axial direction AX end of the lower slide surface 12L, and when the first slide bearing 1L is viewed from the axial direction AX, the portion of the first groove portion 18a located at the axial direction end 8c appears recessed. In the second slide bearing 1U, the axial direction AX end 10c of the first groove portion 18a opens toward the outer region X1 in the axial direction AX of the upper slide surface 12U. The first groove portion 18a has the function of taking in lubricating oil from the outer region X1 and guiding the lubricating oil to the central portion 8d and the central portion 10d in the axial direction AX.

[0026] The second groove portion 18b is closed off from the outer region X1 in the axial direction AX at its end side. Specifically, in the first plain bearing 1L, the axial direction AX end 8c of the first groove portion 18a is located closer to the central portion 8d of the first plain bearing 1L than the axial direction AX end of the lower slide surface 12L, and when the first plain bearing 1L is viewed from the axial direction AX, the portion of the first groove portion 18a located at the axial direction end 8c is recessed and not visible. In the second plain bearing 1U, the axial direction AX end 10c side of the first groove portion 18a is closed off from the outer region X1 in the axial direction AX of the upper slide surface 12U. The second groove portion 18b has the function of guiding lubricating oil to the central portions 8d and 10d in the axial direction AX while preventing lubricating oil flowing on the slide surface 12 from leaking into the outer region X1.

[0027] A plurality of first grooves 18a and a plurality of second grooves 18b are provided. The first grooves 18a and the second grooves 18b are arranged alternately in the rotational direction RS. By arranging the first grooves 18a and the second grooves 18b alternately in this manner, it is possible to prevent lubricating oil taken in from the outer region X1 of the slide surface 12 from leaking to the outer region X1. In addition, the second grooves 18b are provided in the portion of the first region 14 located closest to the second region 16. This allows lubricating oil leaking from the second region 16 to be received and returned to the second region 16 without leaking to the outer region X1.

[0028] The end of the third groove portion 18c in the direction of rotation RS is open toward the outer region X2 of the slide surface 12 in the direction of rotation RS. Specifically, in the first slide bearing 1L, the front end 8a of the third groove portion 18c in the direction of rotation RS is located at the end of the lower slide surface 12L in the direction of rotation RS, and when the first slide bearing 1L is viewed from the direction of rotation RS, the portion of the third groove portion 18c located at the end of the direction of rotation RS appears recessed. The second slide bearing 1U is actually provided in the outer region X2 of the lower slide surface 12L of the first slide bearing 1L. The first slide bearing 1L is actually provided in the outer region X2 of the upper slide surface 12U of the second slide bearing 1U. That is, the rear end 8b of the first slide bearing 1L and the front end 10a of the second slide bearing 1U are adjacent, and the front end 8a of the first slide bearing 1L and the rear end 10b of the second slide bearing 1U are adjacent. Therefore, the outer region X2 actually serves as the boundary between the lower front first region 14LF and the upper rear first region 14UR, and as the boundary between the lower rear first region LR and the upper front first region UF. Therefore, lubricating oil leaking from the upper rear first region 14UR flows into the third groove portion 18c in the lower front first region 14LF. Lubricating oil leaking from the lower rear first region LR flows into the third groove portion 18c in the upper front first region UF. In this way, the third groove portion 18c functions to take in lubricating oil leaking from the adjacent first region 14 and guide the lubricating oil along the rotational direction RS.

[0029] As shown in FIGS. 3 and 4, the second region 16 is provided with a slide surface 12 having a different shape from that of the first region 14 .

[0030] In this embodiment, the second region 16 has a plurality of recesses 20 recessed into the sliding surface 12, lined up in the rotational direction RS. The area occupied by the recesses 20 is approximately 30% of the area of ​​the sliding surface 12 in the second region 16. The recesses 20 in this embodiment have an elliptical shape that is long in the axial direction AX. By giving the recesses 20 this shape, the sliding bearing 1 of this embodiment ensures that the area of ​​the portion where the recesses 20 are not provided is approximately 70% of the area of ​​the sliding surface 12 in the second region 16.

[0031] As shown in FIG. 3 , the lower recesses 20L are arranged so that adjacent lower recesses 20L in the rotational direction RS at least partially overlap each other. In the second region 16, the rotation of the crankshaft 2 pulls the lubricating oil in the rotational direction RS. By overlapping the lower recesses 20L at least partially in this way, the lubricating oil flowing out of one lower recess 20L flows into the lower recess 20L adjacent to it in the rotational direction RS. This allows the lower recesses 20L to prevent a decrease in the strength of the lubricating oil film present between the crankshaft 2 and the lower sliding surface 12L. This reduces friction between the crankshaft 2 and the lower sliding surface 12L, facilitating smooth sliding of the crankshaft 2.

[0032] As shown in Fig. 4, the upper recesses 20U are provided at both ends of the oil supply passage 26 in the axial direction AX. Similar to the lower recesses 20L, the upper recesses 20U are provided such that, as viewed in the rotational direction RS, at least a portion of the upper recesses 20U adjacent to each other in the rotational direction RS overlap. Note that the load applied to the upper second region 16U is smaller than the load applied to the lower second region 16L. Therefore, the area of ​​the upper recesses 20U may be smaller than the area of ​​the lower recesses 20L.

[0033] In the sliding bearing 1 configured in this manner, a load is applied to the second region 16 provided in the vertical direction by the sliding of the piston 24 (see FIG. 2). This load causes the gap between the crankshaft 2 and the sliding surface 12 in the second region 16 to easily fill up. This makes it easier for the lubricating oil that was in this gap to leak out into the outer region X1 of the sliding bearing 1 (see FIG. 5).

[0034] However, in the sliding bearing 1 of the present disclosure, the grooves 18 in the first region 14 take in lubricating oil and guide it in the rotational direction RS, supplying the lubricating oil to the second region 16. The lubricating oil taken in by the grooves 18 may be supplied from the oil holes 22 or from an oil pan (not shown). This makes it possible to compensate for the lubricating oil leaking from the second region 16. As a result, an oil film can be secured between the sliding surface 12 and the crankshaft 2 in the second region 16. As a result, friction between the crankshaft 2 and the sliding surface 12 is reduced, allowing the crankshaft 2 to slide smoothly, and wear on the sliding bearing 1 can be prevented.

[0035] Furthermore, the sliding bearing 1 of the present disclosure has the recess 20 as described above. This makes it easier for the lubricating oil supplied to the second region 16 to remain in the second region. As a result, a decrease in the oil film strength in the second region 16 can be prevented.

[0036] As described above, the present disclosure can provide a sliding bearing that can simultaneously retain lubricating oil and receive a load from a rotating shaft.

[0037] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the invention. In particular, the multiple modifications described in this specification can be combined as needed.

[0038] (a) In the above embodiment, an example was described in which the recesses 20 were provided in the second region 16, but the present disclosure is not limited to this. The second region 16 may have a shape in which the area without recesses 20 or grooves 18 is larger than that of the first region 14. For example, the sliding bearing 1 may not have any recesses 20.

[0039] (b) In the above embodiment, an example was described in which the piston 24 slides up and down, but the piston 24 does not necessarily have to slide up and down in the direction of gravity. For example, the sliding bearing 1 of the present disclosure may be applied to an engine in which the piston 24 slides horizontally, such as a horizontally opposed engine. In this case, the second regions 16 may be located toward the top dead center and toward the bottom dead center of the piston 24.

[0040] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above-described embodiments may be combined in any manner without departing from the spirit of the invention.

[0041] This application is based on a Japanese patent application (Patent Application No. 2023-213490) filed on December 19, 2023, the contents of which are incorporated herein by reference.

[0042] 1: plain bearing, 1L: first plain bearing, 1U: second plain bearing 2: crankshaft (an example of a rotating shaft) 8a: front end, 8b: rear end, 8c: end, 8d: center 10a: front end, 10b: rear end, 10c: end, 10d: center 12: sliding surface, 14: first region, 16: second region 18: groove, 18a: first groove, 18b: second groove, 18c: third groove 20: recess AX: axial direction RS: rotational direction X1: outer region X2: outer region

Claims

1. A sliding bearing having a sliding surface on which a rotating shaft slides, and lubricating oil entering a gap between the rotating shaft and the sliding surface, a first region having a plurality of grooves recessed into the sliding surface and extending from an end portion of the rotating shaft in the axial direction toward a central portion of the rotating shaft while inclining along the rotation direction of the rotating shaft; a second region having the sliding surface of a different shape from that of the first region; Equipped with the first region is provided on both ends of the sliding surface in the rotation direction, the second region is provided between the first regions, The groove portion has a plurality of first groove portions whose end sides in the axial direction are open toward an outer region of the slide surface in the axial direction, and a plurality of second groove portions whose end sides in the axial direction are closed relative to the outer region, the second groove portion is provided on the second region side of each of the first regions provided at both ends of the sliding surface in the rotation direction.

2. The second groove portions are arranged alternately with the first groove portions, 2. The sliding bearing according to claim 1.

3. The sliding bearing is a first plain bearing provided on one side of the rotating shaft, and a second plain bearing provided on the other side of the rotating shaft so as to face the first plain bearing, an end portion of the first plain bearing in the rotational direction overlaps with an end portion of the second plain bearing in the rotational direction, The groove portion is provided in at least the first plain bearing, the end in the rotation direction has a third groove portion that is open toward an outer region of the sliding surface in the rotation direction, 2. The sliding bearing according to claim 1.

4. The second region has a recess that is recessed in the sliding surface and stores the lubricating oil.

2. The sliding bearing according to claim 1.

5. The recessed portions are provided in a plurality in the rotational direction, and at least a portion of adjacent recessed portions in the rotational direction is provided to overlap with each other in the rotational direction.

5. The sliding bearing according to claim 4.