JP5234679B2 - Sliding bearings for internal combustion engines - Google Patents

Description

  The present invention relates to a sliding bearing for an internal combustion engine that supports a crankshaft by combining a pair of semi-cylindrical bearings into a cylindrical shape.

  A conventional plain bearing for a crankshaft uses a cylindrical shape obtained by combining two semi-cylindrical bearings. A circumferential oil groove is formed on the inner peripheral surface of at least one of the pair of semi-cylindrical bearings, and oil supply to the outer peripheral surface of the crank pin is performed via the circumferential oil groove. Generally, this circumferential oil groove has a constant depth (see Patent Document 1).

  On the other hand, in recent years, in response to the downsizing of the oil pump for supplying lubricating oil, in order to reduce the amount of lubricating oil leakage from the bearing end, the oil groove is cut from the bearing center to the bearing end. Proposals have been made to form an aperture that reduces the area (see Patent Documents 2 and 3).

JP-A-8-277831 JP-A-4-219521 JP 2005-69283 A

Regarding the supply of lubricating oil to the internal combustion engine slide bearing, first, it is supplied from the outside of the crankshaft slide bearing into a circumferential oil groove formed on the inner surface of the crankshaft slide bearing, and the lubricant is supplied to the crankshaft. Supplied to the sliding surface of the sliding bearing and the sliding surface of the crankpin sliding bearing.
During the initial operation of the internal combustion engine, foreign matter remaining in the lubricating oil passage tends to be mixed in the lubricating oil supplied to the circumferential groove of the crankshaft slide bearing. The foreign material means metal scraps when the oil passage is cut, casting sand at the time of casting, or the like. This foreign matter accompanies the flow of the lubricating oil due to the rotation of the crankshaft, and in conventional sliding bearings for internal combustion engines, it is discharged together with the lubricating oil through gaps such as crush reliefs and chamfers formed at the circumferential end of the bearing. Is done. However, recent internal combustion engines have increased inertial force (inertia force that foreign matter tries to advance in the circumferential direction) acting on foreign matter having a specific gravity greater than that of lubricating oil due to higher rotation of the crankshaft. Sliding surface portion of the sliding bearing (the other semi-cylindrical bearing) on the side that does not have oil grooves without foreign matter being discharged from the gap portion on the sliding bearing combined end surface (each combined end surface of the pair of semi-cylindrical bearings) The bearing sliding surface is easily damaged by foreign matter.

On the other hand, in order to reduce the amount of lubricating oil leaking from the circumferential end of the bearing, a slide bearing in which a throttle portion is formed in the oil groove at the circumferential end of the semi-cylindrical bearing has been proposed (patent) References 2 and 3). When these sliding bearings are examined from the viewpoint of the foreign matter, the flow velocity of the lubricating oil increases on the downstream side of the throttle portion with respect to the flow direction of the lubricating oil, and the inertial force acting on the foreign matter accompanying the lubricating oil is accordingly increased. There is a problem that the size of the bearing sliding surface further increases, and the chance of foreign matter mixing on the bearing sliding surface further increases.
Thus, an object of the present invention is to provide a slide bearing for an internal combustion engine that is excellent in foreign matter dischargeability.

In light of the above object, according to the first aspect of the present invention, the following plain bearing is provided.
Of the pair of semi-cylindrical bearings, a crankshaft is formed by combining the pair of semi-cylindrical bearings in which an oil groove extending in the circumferential direction is formed on the inner peripheral surface of one semi-cylindrical bearing into a cylindrical shape. For sliding bearings of internal combustion engines to be supported,
The oil groove includes a central portion of a circumferential length of the one semi-cylindrical bearing,
Of the circumferential end faces of the one semi-cylindrical bearing, at least the circumferential end face along the entire axial direction length of one circumferential end face facing the same direction as the rotation direction of the crankshaft. There is an axial groove between the opposite circumferential end faces of the other semi-cylindrical bearing,
The circumferential oil groove and the axial groove communicate with each other, and the circumferential oil groove and the axial groove have different depths at the communicating portion, and the circumferential direction at the one circumferential end surface The groove bottom of the oil groove is in a position that is biased toward the bearing inner peripheral surface side than the groove bottom of the axial groove,
The sliding bearing for an internal combustion engine, wherein a cross-sectional area of the circumferential oil groove in the communication portion is larger than a cross-sectional area of the axial groove.

In the first embodiment of the present invention, the relationship between the groove width (L2) and the groove depth (L1) of the axial groove satisfies L2 <2 × L1.
In the second embodiment of the present invention, the relationship between the groove width (L2) and the groove depth (L1) of the axial groove satisfies L2 <L1.
In 3rd embodiment of this invention, the cross-sectional area of the said axial direction groove | channel in the said communication part is less than 1/2 of the cross-sectional area of the said circumferential direction oil groove.
In the fourth embodiment of the present invention, the circumferential oil groove and the axis are formed on the inner circumferential surface of the one semi-cylindrical bearing over the entire circumferential length of the bearing inner circumferential surface. The directional groove is formed symmetrically with respect to an imaginary plane passing through a position that bisects the axis of the plain bearing and the circumferential length of the one semicylindrical bearing.
In a fifth embodiment of the present invention, the groove depth of the circumferential oil groove is maximum at the center position of the circumferential length, and is gradually reduced toward both circumferential end faces, Therefore, the cross-sectional area of the circumferential oil groove is maximum at the center position of the circumferential length, and gradually decreases toward both circumferential end surfaces.
In the sixth embodiment of the present invention, the axial groove includes a crush relief provided along a bearing inner circumferential surface adjacent to each circumferential end surface of a pair of semi-cylindrical bearings. . Here, the crush relief is a curvature different from the center of curvature of the bearing inner peripheral surface formed by removing the bearing wall of the pair of semi-cylindrical bearings near the circumferential end surface on the inner peripheral surface side. Reduced area with center (refers to the area with reduced thickness towards the circumferential end face, as defined in SAE J506 (see item 3.26, item 6.4), DIN 1497, § 3.2. Mean). “The axial groove includes a crush relief” means that the axial groove is formed with a groove depth from the inner peripheral surface of the virtual bearing that exceeds the thickness reduction by the crush relief.

  According to a second aspect of the present invention, there is provided a semi-cylindrical bearing used as a component of the sliding bearing, which has the circumferential oil groove and is used in combination in a pair. A semi-cylindrical bearing is provided that cooperates with the semi-cylindrical bearing to define the axial groove.

Action (1) During operation of the internal combustion engine, the lubricating oil supplied into the circumferential oil groove at the substantially central portion in the circumferential direction of the one semi-cylindrical bearing is mainly in the circumferential direction according to the rotation of the crankshaft. It flows toward the bearing circumferential end along the oil groove and along the bearing inner circumferential surface (that is, the bearing sliding surface) of the semi-cylindrical bearing. The lubricating oil that has reached the bearing circumferential end hits the bearing circumferential end surface of the other semi-cylindrical bearing not formed with the circumferential oil groove, and the circumferential oil groove and the axial groove At the communication portion, the direction is changed to a right angle and flows in the axial groove, and flows out from the axial end of the slide bearing to the outside of the bearing.
During this time, foreign substances accompanying the lubricating oil also flow in the circumferential oil groove and the axial groove together with the lubricating oil, and are discharged from the axial end of the slide bearing to the outside of the bearing. Foreign matter having a larger specific gravity than lubricating oil tends to move while rolling along the groove bottoms of the circumferential oil groove and the axial groove.
Here, the circumferential oil groove at the communication portion and the axial groove depth at the circumferential end surface of one semi-cylindrical bearing are different, and the groove bottom of the circumferential oil groove is different from the groove bottom of the axial groove. Also moves along the groove bottom because the groove is offset toward the inner peripheral surface of the bearing (that is, the groove depth of the axial groove is larger than the groove depth of the circumferential oil groove). Tendency foreign matter enters directly into the axial groove at the communicating portion, and is less affected by the flow of lubricating oil flowing in the circumferential direction along the bearing inner peripheral surface as the crankshaft rotates. The possibility that the foreign matter is pushed out and moves to the inner peripheral surface of the bearing reduces the possibility of entering between the sliding surface of the slide bearing and the crankshaft. If foreign matter enters between the sliding surface of the slide bearing and the crankshaft, the sliding surface may be damaged by the rolling foreign matter. Therefore, the behavior of the foreign matter in the sliding bearing of the present invention is advantageous. is there. Assuming a case where the groove bottom of the axial groove in the communication portion is located at a position biased toward the bearing inner peripheral surface side than the groove bottom of the circumferential oil groove on the circumferential end surface of the semi-cylindrical bearing, The open part of the circumferential groove is opened at the circumferential end face of one of the semi-cylindrical bearings forming the circumferential groove, and a part of the open part (that is, the groove end) of the circumferential oil groove (the groove bottom side) However, since it is blocked by the circumferential end surface of the other semi-cylindrical bearing that does not form the circumferential oil groove, the foreign matter that has reached the communicating portion cannot directly enter the axial groove. The foreign matter floats to the bearing inner peripheral surface side due to the upward flow of the lubricating oil formed by the blocking portion, and then enters the axial groove. Before entering the axial groove, the crankshaft rotates. Accordingly, it is pushed by the flow of the lubricating oil flowing in the circumferential direction and easily enters between the sliding surface of the slide bearing and the crankshaft. In addition, since the cross-sectional area of the circumferential oil groove in the communicating portion is larger than the cross-sectional area of the axial groove, the lubrication in the axial groove is greater than the flow velocity of the lubricating oil in the circumferential oil groove. The oil flow rate is large, and it is difficult for foreign matter to be affected by the flow of lubricating oil flowing in the circumferential direction along the inner circumferential surface of the bearing as the crankshaft rotates, and the foreign matter is pushed out from the axial groove to the inner circumferential surface of the bearing. By moving, the possibility of entering between the sliding surfaces of the plain bearing and the crankshaft is reduced (see also the third embodiment of the present invention).
(2) In the first and second embodiments of the present invention, the relationship between the groove width (L2) and the groove depth (L1) of the axial groove is L2 <2 × L1 or L2 <L1. . According to this configuration, the foreign matter that rolls along the groove bottom of the axial groove is not easily affected by the flow of the lubricating oil flowing in the circumferential direction along the bearing inner peripheral surface according to the rotation of the crankshaft. The possibility that foreign matter is pushed out of the groove and moves to the inner peripheral surface of the bearing reduces the possibility of entering between the sliding surface of the slide bearing and the crankshaft. In the case of L2 ≧ 2 × L1, the cross-sectional area of the axial groove is made smaller than the cross-sectional area of the circumferential oil groove to increase the oil flow in the axial groove and enhance the foreign matter discharging effect. However, it is easily affected by the flow of the lubricating oil in the circumferential direction near the crankshaft surface due to the rotation of the crankshaft, and it is difficult to discharge foreign matter along the axial groove to the outside of the bearing. Furthermore, when L2 = 3 × L1, the foreign matter discharge effect is hardly expected. Further, in the case of L2 ≧ 3 × L1, the movement of foreign matter to the bearing inner peripheral surface is promoted.
(3) In the fourth embodiment of the present invention, the circumferential oil groove is formed on the inner circumferential surface of the one semi-cylindrical bearing over the entire circumferential length of the bearing inner circumferential surface. The circumferential oil groove and the axial groove form are symmetrical with respect to the axis of the plain bearing and a virtual plane passing through a position that bisects the circumferential length of the one semi-cylindrical bearing. Has been made. If this configuration is adopted, the method of assembling the pair of semi-cylindrical bearings that may occur in the case of the embodiment in which the circumferential oil grooves and the axial grooves are formed in a non-symmetrical manner is mistaken. The trouble of assembling to the crankcase can be eliminated. In other words, in a configuration that does not employ the fourth embodiment, when the crankshaft is supported by combining the pair of semicylindrical bearings, a circumferential end surface that forms an axial groove of the one semicylindrical bearing. However, if the crankshaft is turned to the opposite side of the direction of rotation, the expected effect of the present invention cannot be obtained, but the one half of the fourth embodiment is symmetrical as in the fourth embodiment. If cylindrical bearings are employed, it is not necessary to pay excessive attention when assembling the pair of semi-cylindrical bearings, so that work efficiency can be improved.
(4) In the fifth embodiment of the present invention, the groove depth of the circumferential oil groove is maximum at the center position of the circumferential length of the one semi-cylindrical bearing, and both circumferential ends It is made smaller gradually toward the surface. With this configuration, the circumferential oil groove opening of the one semi-cylindrical bearing can be easily positioned in the axial groove, and the circumferential end face of the mating semi-cylindrical bearing. As a result, a part of the opening is blocked and the flow of the lubricating oil becomes an upward flow, and the foreign matter floats up and is pushed by the flow of the lubricating oil flowing in the circumferential direction according to the rotation of the crankshaft and moves to the inner peripheral surface of the bearing. The occurrence of defects can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of a sliding bearing of an internal combustion engine including a pair of semicylindrical bearings according to Embodiment 1 of the present invention. The inner surface figure of one semi-cylindrical bearing of a pair of semi-cylindrical bearing shown in FIG. The inner surface figure of the other semi-cylindrical bearing of a pair of semi-cylindrical bearings shown in FIG. The front view of the sliding bearing of the internal combustion engine which consists of a pair of semi-cylindrical bearing concerning Example 2 of this invention. The front view of the sliding bearing of the internal combustion engine which consists of a pair of semi-cylindrical bearing concerning Example 3 of this invention. The front view of the sliding bearing of the internal combustion engine which consists of a pair of semi-cylindrical bearing concerning Example 4 of this invention. The supplementary explanatory drawing regarding the function of this invention slide bearing (a part of bearing internal peripheral surface is shown). Another supplemental explanatory drawing regarding the function of this invention slide bearing. Hereinafter, examples and comparative examples of the present invention will be described with reference to the accompanying drawings.

1 to 3 show a plain bearing 10 according to Embodiment 1 of the present invention. The plain bearing 10 includes a pair of semi-cylindrical bearings 20 and 30.
The semi-cylindrical bearing 20 is formed with a circumferential oil groove 22 along the bearing inner circumferential surface 20a at the center position in the bearing width direction over the entire length in the circumferential direction from the inclined surface 26 to the circumferential end surface 24b. Has been. The distance (that is, the groove depth) between the groove bottom of the circumferential oil groove 22 and the bearing inner circumferential surface 20 a is constant over the entire length of the circumferential oil groove 22.

  Further, in the circumferential end surface 24a of the semi-cylindrical bearing 20 (the circumferential end surface of the semi-cylindrical bearing 20 facing the same direction as the rotation direction R of the crankshaft indicated by the arrow R in FIG. 1), the bearing The corners on the inner peripheral surface 20a side (that is, the bearing inner edge) are formed into the inclined surfaces 26 by notches extending over the entire bearing width (W). On the other hand, an inclined surface like the inclined surface 26 is not formed on the circumferential end surface 30a of the semi-cylindrical bearing 30 that contacts the circumferential end surface 24a. Thus, the inclined surface 26 and the circumferential end surface 30 a of the semi-cylindrical bearing 30 define a V-shaped groove, that is, an axial groove A. The axial groove A exists over the entire width of the bearing. The circumferential oil groove 22 is formed so that the open portion (that is, the groove end) is open to the inclined surface 26 of the circumferential end face 24a of the semi-cylindrical bearing 20, and the circumferential oil groove 22 and the axis line The directional groove A communicates with each other in the vicinity of the circumferential end faces 24a, 30a of the semi-cylindrical bearings 20, 30. In this communication portion, the relationship between the circumferential oil groove 22 and the axial groove A is such that the groove bottom of the circumferential oil groove 22 in the communication portion is on the circumferential end surfaces 24a, 30a of the semi-cylindrical bearings 20, 30. In a position deviated from the groove bottom of the axial groove A toward the bearing inner peripheral surface 20a (that is, the groove depth of the circumferential oil groove 22 is smaller than the groove depth of the axial groove A), and The cross-sectional area of the circumferential oil groove 22 is larger than the cross-sectional area of the axial groove A.

In such a configuration, when the crankshaft supported by the slide bearing 10 rotates during operation of the internal combustion engine, the circumference of the semi-cylindrical bearing 20 is accompanied with the rotation of the crankshaft (see the arrow R indicating the rotation direction in FIG. 1). The lubricating oil flows in the direction oil groove 22 in the direction of the arrow. The lubricating oil changes its direction at the communicating portion, flows in the axial groove A, and is discharged from the open ends of the axial groove A to the outside of the bearing. Since the cross-sectional area of the circumferential oil groove 22 is greater than the cross-sectional area of the axial groove A, the flow rate of the lubricating oil increases after the flow is changed at the communicating portion. Therefore, accompanying the flow of the lubricating oil, the movement of the foreign particles moving in the circumferential oil groove 22 and entering the axial groove A is promoted and quickly discharged to the outside of the bearing. Moreover, in the communication portion, the groove depth of the circumferential oil groove 22 is smaller than the groove depth of the axial groove A on the circumferential end faces 24a and 30a of the semi-cylindrical bearings 20 and 30, and lubrication is performed. Since the foreign particles accompanying the oil flow directly enter the axial groove A, the discharge of the foreign particles to the outside of the bearing is promoted, and the bearing inner peripheral surface (bearing sliding surface) 20a and the crankshaft are The opportunity to enter and damage the sliding surfaces of both members is reduced.
In this embodiment, the axial groove A is defined by the inclined surface 26 in the circumferential end surface 24a of the semicylindrical bearing 20 and the normal circumferential end surface 30a of the semicylindrical bearing 30. An inclined surface similar to the inclined surface 26 may be formed symmetrically on the circumferential end surface 30a of the cylindrical bearing 30, and the axial groove A may be defined by both inclined surfaces.

FIG. 4 shows a plain bearing 10A according to Embodiment 2 of the present invention. The slide bearing 10A includes a pair of semi-cylindrical bearings 20A and 30A.
In the semi-cylindrical bearing 20A, a circumferential oil groove 22A along the bearing inner circumferential surface 20a is formed at the center position in the bearing width direction over substantially the entire length in the circumferential direction from the inclined surface 26 to the circumferential end surface 24b. Has been. The distance (that is, the groove depth) between the groove bottom of the circumferential oil groove 22A and the bearing inner circumferential surface 20a is the maximum at the center of the circumferential length of the semi-cylindrical bearing 20A, and the circumferential end surface Each of them gradually decreases toward 24a and 24b.

  Further, in the circumferential end surface 24a of the semi-cylindrical bearing 20A, the corners on the bearing inner peripheral surface 20a side (that is, the bearing inner end edge portion) are formed on the inclined surface 26 by notches extending over the entire width of the bearing. Yes. On the other hand, an inclined surface 36 similar to the inclined surface of the semi-cylindrical bearing 20A is also formed on the circumferential end surface 30a of the semi-cylindrical bearing 30A that contacts the circumferential end surface 24a.

The inclined surfaces 26 and 36 face each other and define a groove having a V-shaped cross section, that is, an axial groove A. The axial groove A exists over the entire width of the bearing. The circumferential oil groove 22A and the axial groove A are formed such that the open portion (that is, the groove end) of the circumferential oil groove 22 opens to the inclined surface 26 of the circumferential end surface 24a of the semi-cylindrical bearing 20A. The semi-cylindrical bearings 20A and 30A communicate with each other in the vicinity of the circumferential end faces 24a and 30a. In this communication portion, the relationship between the circumferential oil groove 22A and the axial groove A is such that the groove bottom of the circumferential oil groove 22A in the communication portion is on the circumferential end surfaces 24a, 30a of the semi-cylindrical bearings 20A, 30A. In a position displaced toward the bearing inner peripheral surface 20a side from the groove bottom of the axial groove A (that is, the groove depth of the circumferential oil groove 22A is smaller than the groove depth of the axial groove A), and The cross-sectional area of the circumferential oil groove 22A is larger than the cross-sectional area of the axial groove A.
The inclined surfaces such as the inclined surfaces 26 and 36 do not exist on the circumferential end surface on the opposite side of the semi-cylindrical bearings 20A and 30A.

  An oil hole (through hole) (not shown) for supplying lubricating oil from the outside of the bearing into the circumferential oil groove 22A inside the bearing is formed at the center of the circumferential length of the semi-cylindrical bearing 20A. Since the groove depth of the circumferential oil groove 22A is the maximum at the location where the oil hole exists, the foreign particles accompanying the lubricating oil supplied into the circumferential oil groove 22A through the oil hole are Difficult to move out of the directional oil groove 22A. Further, since the groove depth of the circumferential oil groove 22A is gradually reduced from the central portion of the circumferential length toward the circumferential end faces 24a and 24b, respectively, The flow rate of the lubricating oil is large at a position close to the circumferential end surface 24a, and the circumferential inertia force of the foreign particles accompanying the lubricating oil is also large, but in the communicating portion between the circumferential oil groove 22A and the axial groove A, Since the groove depth of the axial groove A in the communicating portion is larger than the groove depth of the circumferential oil groove 22A on the circumferential end faces 24a, 30a of the semi-cylindrical bearings 20A, 30A, the foreign particles are in the axial groove A. Due to the difference in the cross-sectional area between the circumferential oil groove 22A and the axial groove A, the moving speed of the foreign particles in the axial groove A where the lubricating oil flow rate is large is large, and the foreign particles are quickly transferred to the outside of the bearing. To be discharged. In the embodiment, the inclined surfaces 26 and 36 have the same shape, but the inclined surfaces 26 and 36 do not necessarily have the same shape.

FIG. 5 shows a plain bearing 10B according to Embodiment 3 of the present invention. The plain bearing 10B includes a pair of semi-cylindrical bearings 20B and 30A.
In the semi-cylindrical bearing 20B, a circumferential oil groove 22B along the bearing inner circumferential surface 20a is formed at the center position in the bearing width direction from the inclined surface 26 described later to a position close to the other circumferential end surface 24b. . The circumferential oil groove 22B has a groove depth that gradually decreases from the central portion of the semi-cylindrical bearing 20B to the circumferential end faces 24a and 24b. However, the circumferential oil groove 22B extends to the circumferential end surface 24a, but does not reach the circumferential end surface 24b. This is because an oil hole (through hole) (not shown) for supplying lubricating oil from the outside of the bearing into the circumferential oil groove 22B inside the bearing is formed at the center of the circumferential length of the semi-cylindrical bearing 20B. The lubricating oil supplied into the circumferential oil groove 22B is directed toward the circumferential end surface 24a located in the same direction as the rotation direction R of the crankshaft indicated by an arrow in FIG. Because it flows.

  In addition, in the circumferential end surface 24a of the semi-cylindrical bearing 20B, the corner portion on the bearing inner peripheral surface 20a side (that is, the bearing inner end edge portion) is formed on the inclined surface 26 by a notch extending over the entire width of the bearing. Yes. On the other hand, an inclined surface 36 similar to the inclined surface of the semi-cylindrical bearing 20B is also formed on the circumferential end surface 30a of the semi-cylindrical bearing 30A that is in contact with the circumferential end surface 24a.

The inclined surfaces 26 and 36 face each other and define a groove having a V-shaped cross section, that is, an axial groove A. The axial groove A exists over the entire width of the bearing. The circumferential oil groove 22B and the axial groove A are formed so that the open portion (that is, the groove end) of the circumferential oil groove 22 is opened at the inclined surface 26 of the circumferential end surface 24a of the semi-cylindrical bearing 20B. The semi-cylindrical bearings 20B and 30A communicate with each other in the vicinity of the circumferential end faces 24a and 30a. In this communication portion, the relationship between the circumferential oil groove 22B and the axial groove A is such that the groove bottom of the circumferential oil groove 22B in the communication portion is on the circumferential end faces 24a, 30a of the semi-cylindrical bearings 20B, 30A. In a position displaced toward the bearing inner peripheral surface 20a side from the groove bottom of the axial groove A (that is, the groove depth of the circumferential oil groove 22B is smaller than the groove depth of the axial groove A), and The cross-sectional area of the circumferential oil groove 22B is larger than the cross-sectional area of the axial groove A.
The inclined surfaces such as the inclined surfaces 26 and 36 do not exist on the circumferential end surface on the opposite side of the semi-cylindrical bearings 20B and 30A.

  The effect of the semi-cylindrical bearing 20B having the circumferential oil groove 22B and the axial groove A is equivalent to the effect of the semi-cylindrical bearing 20B of the second embodiment.

FIG. 6 shows a plain bearing 10C according to the fourth embodiment of the present invention. The plain bearing 10C includes a pair of semi-cylindrical bearings 20C and 30B.
The semi-cylindrical bearing 20C is formed with a circumferential oil groove 22C along the bearing inner peripheral surface 20a at the center position in the bearing width direction over the entire length in the circumferential direction from the inclined surfaces 26 to 28 described later. Similar to the circumferential oil groove 22A in the second embodiment, the circumferential oil groove 22C gradually increases in depth from the central portion of the circumferential length toward the circumferential end faces 24a and 24b. Has been made small.

  Further, in the circumferential end face 24a of the semi-cylindrical bearing 20C, the corners on the bearing inner peripheral face 20a side (that is, the bearing inner end edge part) are formed on the inclined face 26 by notches extending over the entire width of the bearing. Yes. On the other hand, an inclined surface 36 similar to the inclined surface 26 of the semi-cylindrical bearing 20C is also formed on the circumferential end surface 30a of the semi-cylindrical bearing 30B that contacts the circumferential end surface 24a. Thus, the inclined surfaces 26 and 36 define a V-shaped groove, that is, an axial groove A. The axial groove A exists over the entire width of the bearing.

  The formation form of each groove along the bearing inner peripheral surface of the semi-cylindrical bearing 20C is bilaterally symmetric in FIG. 6, and is formed on the circumferential end surfaces 24b and 30b located on the opposite side to the circumferential end surfaces 24a and 30a. Also, inclined surfaces 28 and 38 similar to the inclined surfaces 26 and 36 are formed, and a V-shaped axial groove B similar to the axial groove A is formed.

  The intended effects of the sliding bearing 10C are also the same as the effects of the second and third embodiments. The semi-cylindrical bearings 20C and 30B are formed in a symmetrical shape in FIG. 6 when the assembling relationship of the semi-cylindrical bearings 20C and 30B with respect to the crankshaft is wrong. This is because, if the asymmetric structure is provided with a single axial groove A as described above, the intended effect of eliminating foreign matters accompanying the lubricating oil to the outside of the bearing cannot be obtained. That is, the axial groove B is formed along the circumferential end face 24b of the semi-cylindrical bearing 20C facing the direction opposite to the rotation direction of the crankshaft (see arrow R in FIG. 6). The intended effect cannot be obtained.

[Supplementary explanation regarding the function of the plain bearing of the present invention]
This will be described with reference to FIG. FIG. 7 shows, for example, the axial groove A 1 of the plain bearing 10A shown in FIG. 4 viewed from the bearing inner surface side.
In the drawing, the arrow I indicates that the lubricating oil supplied into the circumferential oil groove 22A through the oil hole located at the circumferential center of the semi-cylindrical bearing 20A is in the circumferential direction as the crankshaft rotates. The direction which flows toward the end surface 24a is shown. Not all of the lubricating oil flows in the circumferential oil groove 22A, but also enters the bearing inner peripheral surface, which is outside the circumferential oil groove 22A, and flows as indicated by an arrow I. An arrow II indicates the moving direction of the foreign particle F.

The foreign particle F accompanying the lubricating oil moves along the circumferential bottom surface 24a together with the lubricating oil while rolling along the groove bottom of the circumferential oil groove 22A. The communication part of the groove A is reached. In this communication portion, the groove depth of the axial groove A in the circumferential end surface 24a of the semi-cylindrical bearing 20 is made larger than the groove depth of the circumferential oil groove 22A in the communication portion. Since the open portion (groove end) of the circumferential oil groove 22 is on the inclined surface 26, the open portion (groove end) of the circumferential oil groove is formed by the circumferential end surface 30a of the semi-cylindrical bearing 30 that does not form the circumferential oil groove. ) Part (groove bottom side) is not blocked. For this reason, the foreign matter that has reached the communication portion directly enters the axial groove A without floating on the inner peripheral surface side of the bearing. Further, in the communication portion, since the cross-sectional area of the axial groove A is smaller than the cross-sectional area of the circumferential oil groove 22A, the direction is changed from the circumferential oil groove 22A into the axial groove A. The flow rate of the flowing lubricating oil increases in the axial groove A. Accordingly, the foreign particles that have reached the communicating portion are quickly discharged outside the bearing along the increased lubricant flow in the axial groove A. Thus, since the moving speed of the foreign particles in the axial groove A is high, the foreign particles are not pushed by the lubricating oil flow along the bearing inner peripheral surface 20a indicated by the arrow I, and the foreign particles are pushed out from the axial groove A. Thus, the phenomenon of moving toward the semi-cylindrical bearing 30 with the lubricating oil flow can be suppressed. Further, if the groove depth of the axial groove A is increased and / or the groove width of the axial groove A is decreased in the communication portion, the influence of the lubricating oil flow I on the foreign particles is reduced accordingly. it can.
This state is shown in FIG. In the figure, C is a crankshaft, and the groove depth of the axial groove A is indicated as L1, and the groove width is indicated as L2. If the relationship between L1 and L2 is 2 × L1> L2 and the groove width of the axial groove is set small and the groove depth of the axial groove A is set large, lubricating oil for foreign particles in the axial groove A is set. If the influence of the flow I can be sufficiently reduced and L1> L2 is set, a more desirable effect can be obtained. In addition, it is desirable to set the relationship between L1 and L2 so that the groove depth L1 of the axial groove is 0.15 mm or more and the groove width L2 is 1 mm or less.

10, 10A, 10B, 10C Slide bearing 20, 20A, 20B, 20C Semi-cylindrical bearing 20a Bearing inner peripheral surface 22, 22A, 22B, 22C Circumferential oil groove 24a, 24b Circumferential end surface 28 Inclined surface 26, 26a Inclined surface 30, 30A, 30B Semi-cylindrical bearing 30a Circumferential end surface 36, 36a Inclined surface 38 Inclined surface A Axial groove C Crank shaft R Rotating direction of crank shaft W Bearing width L1 Depth of axial groove L2 Axis Groove width of direction groove

Claims (6)

Of the pair of semi-cylindrical bearings, the pair of semi-cylindrical bearings in which circumferential oil grooves extending in the circumferential direction are formed on the inner circumferential surface of one semi-cylindrical bearing are combined into a cylindrical shape. In a sliding bearing for an internal combustion engine that supports a crankshaft,
The circumferential oil groove includes a central portion of the circumferential length of the one semi-cylindrical bearing,
Of the circumferential end faces of the one semi-cylindrical bearing, at least the circumferential end face along the entire axial direction length of one circumferential end face facing the same direction as the rotation direction of the crankshaft. There is an axial groove between the opposite circumferential end faces of the other semi-cylindrical bearing,
The axial groove extends across the entire axial width of the slide bearing along at least the inner circumferential surface of the one semi-cylindrical bearing and the one circumferential end surface of the pair of semi-cylindrical bearings. Is defined by an inclined surface formed by
The circumferential oil groove and the axial groove communicate with each other, and the circumferential oil groove at the communicating portion and the depth of the axial groove at the one circumferential end surface are different, and the circumferential direction The groove bottom of the oil groove is in a position that is biased toward the bearing inner peripheral surface side than the groove bottom of the axial groove,
The sliding bearing for an internal combustion engine, wherein a cross-sectional area of the circumferential oil groove in the communication portion is larger than a cross-sectional area of the axial groove. The cross-sectional area of the axial groove in the communicating portion, the circumferential oil groove sliding bearing for an internal combustion engine according to claim 1, characterized in that less than half of the cross-sectional area of the. The circumferential oil groove is formed in the bearing inner circumferential surface of the one semi-cylindrical bearing over the entire circumferential length of the bearing inner circumferential surface,
The formation form of the circumferential oil groove and the axial groove is based on an imaginary plane passing through a position that bisects the axial line of the sliding bearing and the circumferential length of the one semi-cylindrical bearing. 3. A plain bearing for an internal combustion engine according to claim 1 or 2, wherein the bearing is symmetrical. The groove depth of the circumferential oil groove is the maximum at the center position of the circumferential length, and is gradually reduced toward both circumferential end faces, thereby having a transverse area of the circumferential oil groove. There is a maximum at the center position of the circumferential length, according to any one of claims 1, characterized in that said has circumferentially opposite end faces gradually smaller toward the up claims 3 A plain bearing for an internal combustion engine. It said axial groove, from claim 1, characterized in that it comprises the crush relief to be applied along the inner circumferential bearing surface adjacent to the circumferential end surfaces of the pair of semi-cylindrical bearing to claim 4 A plain bearing for an internal combustion engine according to any one of the preceding claims. A semi-cylindrical bearing used as a component of a sliding bearing of an internal combustion engine according to any one of claims 1 to 5 ,
A semi-cylindrical bearing having the circumferential oil groove and defining the axial groove in cooperation with a mating semi-cylindrical bearing used in combination.