JP2014209036A - Internal combustion engine crankshaft main bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine crankshaft main bearing having an excellent foreign matter discharge function while reducing oil leakage.SOLUTION: According to the present invention, a main bearing 19 constituted by a pair of semi-cylindrical bearings 17 and 18 is provided. An oil groove 17a extending in a circumferential direction and arranged so that a center of an axial width matches that of an inlet opening 26 of a lubricant path 10a formed in a journal part 10 of a crankshaft is provided on an inner circumferential surface 17S of one semi-circular bearing 17. The oil groove 17a does not extend up to an axial groove 24A formed in a joint portion between the pair of semi-cylindrical bearings 17a and 18, so that a divided inner circumferential surface 17S' extends between a circumferential end portion 17E of the oil groove 17a and a circumferential end surface 17A of the semi-cylindrical bearing 17. A circumferential length L1 of the divided inner circumferential surface 17S' is smaller than a circumferential length L2 of the inlet opening 26, so that the oil groove 17a is communicable with the axial groove 24A via the inlet opening 26.

Description

  The present invention relates to a main shaft bearing for a crankshaft of an internal combustion engine, and more particularly to a main bearing for supporting a journal portion of the crankshaft at a lower portion of a cylinder block of the internal combustion engine. Furthermore, the present invention also relates to a bearing device composed of such a main bearing and a corresponding shaft portion.

  The crankshaft of the internal combustion engine is supported at the lower part of the cylinder block of the internal combustion engine via a main bearing comprising a pair of semi-cylindrical bearings at its journal portion. In order to lubricate the main bearing, the lubricating oil discharged by the oil pump passes through the oil gallery formed in the cylinder block wall and the through hole formed in the main bearing wall to the inner peripheral surface of the main bearing. It is fed into the lubricating oil groove formed along the same. A first lubricating oil passage is formed in the crankshaft so as to penetrate the journal portion in the diametrical direction, and communicates with the lubricating oil groove of the main bearing at both end openings. Further, the second lubricating oil passage is formed so as to branch from the first lubricating oil passage and pass through the crank arm portion, and communicates with a third lubricating oil passage formed penetrating in the diameter direction of the crank pin. Accordingly, the lubricating oil fed into the lubricating oil groove of the main bearing passes through the first lubricating oil passage, the second lubricating oil passage, and the third lubricating oil passage, and then the end opening (crank of the third lubricating oil passage). It is supplied to the sliding surface between the crank pin and the connecting rod bearing from a lubricating oil outlet formed on the outer peripheral surface of the pin.

  The lubricating oil groove of the main bearing is formed on the inner peripheral surface of at least one of the pair of semicylindrical bearings over the entire length in the circumferential direction (FIG. 1 of Patent Document 1). In this case, the lubricating oil supplied from the oil gallery in the cylinder block to the lubricating oil groove of the main bearing mainly flows to the circumferential end of the semi-cylindrical bearing according to the rotation of the journal part, and most of the lubricating oil It is discharged out of the bearing through an axial groove formed at the joint of the semi-cylindrical bearing.

  Further, in recent years, in order to reduce the amount of lubricating oil leaked from the circumferential end of the semi-cylindrical bearing in response to the downsizing of the oil pump for supplying lubricating oil for the purpose of reducing the fuel consumption of the internal combustion engine. Further, the circumferential length of the lubricating oil groove is configured to be shorter than the total circumferential length of the semi-cylindrical bearing, so that at least one of both circumferential ends of the lubricating oil groove is the circumferential end of the semi-cylindrical bearing. A main bearing that does not extend to the part (not opened by an axial groove) is also used (see Patent Documents 1 to 5).

Japanese Utility Model Publication No. 61-00573 Japanese Patent Laid-Open No. 04-219521 JP-A-2005-249024 JP 2011-179572 A JP 2008-095858 A

  Lubricating oil sent from the oil gallery in the cylinder block to the connecting rod bearing through the internal lubricating oil passages of the main bearing and the crankshaft may be accompanied by, for example, residual foreign matter generated during processing of each part. This foreign matter may damage the sliding surface between the journal portion and the main bearing and the sliding surface between the crankpin and the connecting rod bearing, and therefore needs to be quickly discharged from the lubricating oil flow.

  In a conventional main bearing in which a lubricating oil groove is formed on the inner peripheral surface over the entire circumferential length of the semi-cylindrical bearing, the lubricating oil supplied from the oil gallery in the cylinder block to the lubricating oil groove of the main bearing is Since it can flow to the circumferential end of the semi-cylindrical bearing, foreign matter accompanying the lubricating oil can be discharged to the outside of the bearing through a gap formed by the axial groove and the journal portion of the main bearing. it can. However, as described above, in order to reduce the amount of lubricating oil leakage from the axial groove in response to the downsizing of the oil pump for supplying lubricating oil, at least one of the circumferential ends of the lubricating oil groove is axially In the case of a main bearing configured so as not to reach the groove, not only the lubricating oil but also foreign matters are not easily discharged from the lubricating oil groove of the main bearing, and tend to stay near the circumferential end of the lubricating oil groove. .

  The foreign matter staying near the circumferential end of the lubricating oil groove causes damage to the sliding surface between the journal portion and the main bearing. Further, these foreign substances enter the lubricating oil passage inside the crankshaft when the inlet opening of the first lubricating oil passage formed on the outer peripheral surface of the journal portion passes near the end of the lubricating oil groove, and the crankpin and the connecting rod bearing It is sent to the sliding surface between them, which also causes damage. As a result, the main bearing configured such that at least one of the circumferential ends of the lubricating oil groove does not reach the axial groove reduces the life of the connecting rod bearing as well as the main bearing itself.

  Accordingly, an object of the present invention is to lubricate the main bearing having an excellent foreign matter discharging function while reducing the amount of oil leakage, that is, lubrication from the circumferential end of the lubricating oil groove formed on the inner peripheral surface of the bearing to the axial groove. It is an object of the present invention to provide a main bearing capable of preventing a large amount of foreign matter from staying at the circumferential end of a lubricating oil groove while suppressing oil outflow. Another object of the present invention is to provide a bearing device comprising such a main bearing and a journal portion.

In order to achieve the above object, according to a first aspect of the present invention, the following crankshaft main bearing for an internal combustion engine is provided.
A crankshaft main bearing for an internal combustion engine for rotatably supporting a journal portion of a crankshaft, wherein the journal portion includes a lubricating oil passage extending therein and the lubrication formed on an outer peripheral surface thereof. In the main bearing having the oil passage inlet opening,
The main bearing is composed of a pair of semi-cylindrical bearings, and only one of the semi-cylindrical bearings has an oil groove formed on an inner peripheral surface thereof;
The oil groove extends in the circumferential direction through at least the circumferential center portion of the one semi-cylindrical bearing, and the center of the width of the oil groove in the axial direction is the center of the inlet opening of the journal portion. The circumferential end of the oil groove does not extend to the circumferential end surface of the one semi-cylindrical bearing, and therefore the circumferential end of the oil groove and the one The inner peripheral surface extends between the end surface in the circumferential direction of the semi-cylindrical bearing and provides a separated inner peripheral surface,
The circumferential end surface where the oil groove of the one semi-cylindrical bearing does not extend, and the circumferential end surface of the other semi-cylindrical bearing joined thereto are inclined surfaces extending over the entire length in the axial direction. Each of the inner circumferential surfaces has an axial groove at the joint of the pair of semi-cylindrical bearings, and the separated inner circumferential surface extends between the axial groove and the oil groove. Further, a circumferential length L1 of the separation inner peripheral surface is made smaller than a circumferential length L2 of the inlet opening of the journal portion, and therefore the oil groove passes through the inlet opening of the lubricating oil passage. A main bearing for a crankshaft of an internal combustion engine capable of communicating with the axial groove.

In one embodiment of the present invention, a circumferential length L1 of the separation inner peripheral surface and a circumferential length L2 of the inlet opening of the journal portion are as follows:
L2-L1 ≧ 0.5mm
Meet.

In another embodiment of the present invention, the circumferential length L1 of the separation inner peripheral surface and the circumferential length L2 of the inlet opening of the journal portion are as follows:
L1 ≧ L2 × 0.3
Meet.
More preferably, the circumferential length L1 of the separation inner peripheral surface and the circumferential length L2 of the inlet opening of the journal portion are as follows:
L1 ≧ L2 × 0.6
Meet.

In still another embodiment of the present invention, the depth of the axial groove from the inner peripheral surface of the main bearing is 0.1 to 1 mm.
More preferably, the depth of the axial groove from the inner peripheral surface of the main bearing is 0.1 to 0.5 mm.

  In still another embodiment of the present invention, a circumferential width of the axial oil groove on the inner peripheral surface of the main bearing is 0.2 to 2 mm.

  In yet another embodiment of the present invention, both circumferential ends of the oil groove do not extend to the respective circumferential end faces of the one semi-cylindrical bearing, and thus the circumference of the oil groove The separation inner peripheral surface is provided on both sides in the direction.

In still another embodiment of the present invention, a crush relief is formed on the inner peripheral surface side adjacent to each circumferential end surface of the pair of semi-cylindrical bearings.
Preferably, the end portion of the crush relief on the center side in the circumferential direction of the one semi-cylindrical bearing is located on the circumferential end surface side from the circumferential end portion of the oil groove.

In still another embodiment of the present invention, an area of the inlet opening on the outer peripheral surface of the journal portion is larger than a cross-sectional area of the lubricating oil passage in the journal portion, and therefore, between the inlet opening and the lubricating oil passage. Is formed with a flow passage transition portion in which the cross-sectional area gradually changes.
Preferably, the depth dimension of the flow path transition portion from the outer peripheral surface of the journal portion is 1 to 2 mm.

  According to the 2nd viewpoint of this invention, the bearing apparatus comprised from the crankshaft main bearing by the 1st viewpoint mentioned above and the said journal part supported by this main bearing is provided.

  With the configuration of the present invention, the lubricating oil supplied into the lubricating oil groove through the through-hole formed in the wall of the main bearing is separated from the circumferential end of the oil groove and the axial groove. While the inner peripheral surface suppresses the outflow from the axial groove of the main bearing, the foreign matter accompanying the lubricating oil is removed when the inlet opening of the journal portion passes over the separation inner peripheral surface. Can be appropriately discharged from the axial groove of the main bearing.

  Other objects, features and advantages of the present invention will become apparent from the following description of embodiments of the present invention with reference to the accompanying drawings.

The schematic diagram which cut | disconnected the crankshaft of the internal combustion engine in the journal part and the crankpin part, respectively. 1 is a front view of a crankshaft main bearing and a crankshaft according to Embodiment 1 of the present invention. The top view which looked at the semi-cylindrical bearing above the main bearing shown in FIG. 2 from the bearing inner peripheral surface side. The top view which looked at the semi-cylindrical bearing of the lower side of the main bearing shown in FIG. 2 from the bearing inner peripheral surface side. The expanded sectional view seen from the axial direction of the junction part of the main bearing shown in FIG. 2, and a crankshaft. The figure which looked at the joined part of the main bearing shown in Drawing 2 from the bearing inner peripheral surface side. The enlarged front view of the junction part of the main bearing shown in FIG. The expanded sectional view seen from the axial direction of the other example of the junction part of the main bearing shown in FIG. 2, and a crankshaft. The expanded sectional view which looked at one junction part from the axial direction for demonstrating the function of the main bearing shown in FIG. The expanded sectional view which looked at one junction part from the axial direction for demonstrating the function of the main bearing shown in FIG. The figure which looked at one joined part from the bearing inner peripheral surface side for demonstrating the function of the main bearing shown in FIG. The expanded sectional view which looked at the other joined part from the direction of an axis for explaining the function of the main bearing shown in FIG. The expanded sectional view seen from the axial direction of the junction part of the main bearing shown in FIG. 2 at the time of providing a crush relief. The figure which looked at the joined part of the main bearing shown in Drawing 13 from the bearing inner peripheral surface side. The expanded sectional view seen from the axial direction of the junction part of the main bearing shown in FIG. 2 at the time of providing the crush relief different from FIG. The front view of the main bearing for crankshafts by Example 2 of this invention. The front view of the main bearing for crankshafts by Example 3 of this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a schematic view in which a crankshaft of an internal combustion engine is cut at a journal portion and a crankpin portion, and shows a journal portion 10, a crankpin 12 and a connecting rod 14. As a positional relationship of these three members in the depth direction of the paper surface, the journal portion 10 is on the back side of the paper surface and the crank pin 12 is on the near side, and the crank pin 12 is connected to the large end of the connecting rod 14 carrying the piston on the other end. The housing 16 is enclosed.

  The journal portion 10 is supported by a cylinder block lower portion (not shown) of the internal combustion engine via a main bearing 19 composed of a pair of semi-cylindrical bearings 17 and 18. Only in the semi-cylindrical bearing 17 located on the upper side in the drawing, an oil groove 17a extending in the circumferential direction is formed on the inner peripheral surface except for the region near both ends of the main bearing. The journal portion 10 has a through hole (lubricating oil passage) 10a in the diameter direction, and when the journal portion 10 rotates in the arrow X direction, the inlet openings at both ends of the through hole 10a communicate with the oil groove 17a alternately. Note that if the oil groove is formed in both the upper and lower semi-cylindrical bearings 17 and 18, the amount of lubricating oil leaked from the main bearing 19 will increase. It needs to be formed only on one of the cylindrical bearings.

  A lubricating oil passage 20 is formed inside the crankshaft so as to pass through the journal portion 10, a crank arm (not shown), and the crankpin 12 and communicate with the through hole 10 a.

  The crankpin 12 has a large connecting rod 14 (consisting of a connecting rod side large end housing 16A and a cap side large end housing 16B) via a connecting rod bearing 22 including a pair of semi-cylindrical bearings 22a and 22b. It is held by the end housing 16.

  2 to 7 show details of the pair of semi-cylindrical bearings 17 and 18 constituting the main bearing 19. The semi-cylindrical bearing 17 on the upper side of the drawing has a front circumferential end surface 17A disposed on the front side in the rotation direction X of the journal portion 10 and a rear circumferential end surface 17B disposed on the rear side. The lower semi-cylindrical bearing 18 has a front circumferential end surface 18B disposed on the front side in the rotational direction X of the journal portion 10 and a rear circumferential end surface 18A disposed on the rear side. The front circumferential end surface 17A of the semi-cylindrical bearing 17 is in contact with the rear circumferential end surface 18A of the semi-cylindrical bearing 18, and the front circumferential end surface 18B of the semi-cylindrical bearing 18 is a semi-cylindrical bearing. 17 is in contact with the circumferential end surface 17B on the rear side, thereby forming a cylindrical main bearing 19.

  The front circumferential end surface 17A and the rear circumferential end surface 17B of the semi-cylindrical bearing 17 have inclined surfaces 17C and 17D formed in a chamfered manner over the entire length in the axial direction on the inner circumferential surface side, respectively. The front-side circumferential end surface 18B and the rear-side circumferential end surface 18A of the semi-cylindrical bearing 18 have inclined surfaces 18D, 18C that are similarly formed on the inner circumferential surface over the entire length in the axial direction. As a result, axial grooves 24A and 24B are formed at the joints of the semi-cylindrical bearings 17 and 18, respectively.

  As understood from FIG. 2, the oil groove 17a formed on the inner peripheral surface 17S of the semi-cylindrical bearing 17 has a certain depth in a region including the central portion in the circumferential direction, and in the vicinity of the circumferential end portion. In the region, the depth gradually decreases toward the end. The circumferential ends 17E and 17F of the oil groove 17a do not extend to the inclined surface 17C and the inclined surface 17D, respectively, and therefore, between the end 17E and the inclined surface 17C and between the end 17F and the inclined surface 17D. The inner peripheral surface 17S extends (FIGS. 3 and 5). In this specification, hereinafter, the portion of the inner peripheral surface 17S extending over the circumferential length (linear distance) L1 so as to separate the circumferential end 17E and the inclined surface 17C of the oil groove 17a is separated. This is referred to as an inner peripheral portion 17S ′ (shaded portion in FIG. 6).

  As understood from FIG. 3, the oil groove 17 a is disposed at the center of the width in the axial direction of the semi-cylindrical bearing 17. A through hole (not shown) that penetrates the semi-cylindrical bearing 17 in the radial direction is formed at the bottom of the oil groove 17a, and the lubricating oil is supplied from the oil gallery in the wall of the cylinder block through the through hole. Supplied in. A part of the lubricating oil then flows forward in the rotational direction in the oil groove 17a according to the rotation of the journal portion 10 in the direction of arrow X, and the other part of the lubricating oil flows in the direction opposite to the rotational direction in the oil groove 17a. . The semi-cylindrical bearing 17 is also arranged so that the center in the width direction of the oil groove 17a is aligned with the center of the inlet opening 26 of the lubricating oil passage 10a of the journal portion 10 (FIG. 6 shows the rotation of FIG. 5). The inlet opening 26 in position is indicated by a broken line), and the lubricating oil supplied in the oil groove 17a can further flow to the connecting rod bearing 22 through the inlet opening 26. Although the dimension of the inlet opening 26 of the lubricating oil passage 10a in the journal portion 10 varies depending on the specifications of the internal combustion engine, for example, in the case of a small internal combustion engine for a passenger car, the diameter is about 5 to 8 mm.

  In FIG. 5, the inlet opening 26 is described as having the same cross-sectional area as the lubricating oil passage 10a. However, the inlet opening 26 may have a larger cross-sectional area than the lubricating oil passage 10a as shown in FIG. 8 as a result of processing, and has a circular or elliptical opening shape on the outer peripheral surface of the journal portion 10. You may do it. When the cross-sectional area of the inlet opening 26 is larger than the cross-sectional area of the lubricating oil passage 10a, the flow passage transition portion 29 where the cross-sectional area gradually changes in the oil passage direction between the inlet opening 26 and the lubricating oil passage 10a has a depth of 1. Formed up to ˜2 mm. In any case, the inlet opening 26 has a circumferential length (linear distance) L2 on the outer peripheral surface of the journal portion 10.

  When the foreign matter 28 is mixed in the lubricating oil supplied to the oil groove 17a, the foreign matter 28 moves to one of both circumferential ends of the oil groove 17a due to a difference in specific gravity with the lubricating oil (FIG. 5). . In conventional crankshaft main bearings, this foreign matter stays at the circumferential end of the oil groove, causing damage to the sliding surface between the journal and main bearing, or the inlet opening of the journal is oil When passing over the circumferential end of the groove, it flows into the lubricating oil passage together with the lubricating oil, causing damage to the sliding surface between the crankpin and the connecting rod bearing. However, according to the embodiment of the present invention, the circumferential length L1 of the separation inner peripheral portion 17S ′ is formed to be smaller than the circumferential length L2 of the inlet opening 26, and accordingly, the inlet 10 is rotated as the journal portion 10 rotates. When the opening 26 passes over the end 17E of the oil groove 17a (see FIG. 9), the foreign matter 28 that has entered the lubricating oil passage 10a has the inlet opening 26 positioned on the separation inner peripheral surface 17S ′, thereby When the oil groove 17a communicates with the axial groove 24A via the inlet opening 26 (see FIG. 10), the oil groove 17a is discharged to the axial groove 24A.

  More specifically, when the oil groove 17a communicates with the axial groove 24A via the inlet opening 26, (1) centrifugal force F1 due to rotation of the journal portion 10, and (2) the oil groove 17a and the lubricating oil passage 10a. The flow F2 due to the pressure gradient of the lubricating oil and the flow F3 due to the pressure gradient of the lubricating oil in the lubricating oil passage 10a and the axial groove 24A are the foreign matter 28 inside the lubricating oil passage 10a in the vicinity of the inlet opening 26. In addition, a flow of lubricant sufficient to act on the lubricant at the same time and move the foreign matter 28 entering the lubricant passage 10a to the axial groove 24A is instantaneously formed. At this moment, a flow in the axial direction of the main bearing 19 is also formed in the axial groove 24A to help discharge foreign matter 28 out of the bearing (FIG. 11).

  Thereafter, the communication between the oil groove 17a and the axial groove 24A is interrupted with the rotation of the journal portion 10 (see, for example, FIG. 8), and the axial flow in the axial groove 24A is also reduced. The outflow of lubricating oil is suppressed.

  Furthermore, according to the present invention, the operation described above is performed as shown in FIG. 12 even at the moment when the oil groove 17a and the axial groove 24B communicate with each other through the inlet opening 26 at the rotation direction rear end 17F of the oil groove 17a. Since F1-3 operate | moves, a foreign material can be discharged | emitted, reducing the leakage amount of lubricating oil.

  According to the present invention, the circumferential length L1 of the separation inner circumferential portion 17S 'is required to be smaller than the circumferential length L2 of the inlet opening 26. In the case of L1 ≧ L2, when the inlet opening 26 starts to communicate with the axial groove 24A, the inlet opening 26 is not already in communication with the oil groove 17a, and therefore the flow F2 from the oil groove 17a shown in FIG. This is because the foreign matter 28 that has entered the lubricating oil passage 10a cannot be pushed away into the axial groove 24A.

  The circumferential length L1 of the separating inner peripheral portion 17S ′ and the circumferential length of the inlet opening 26 are sufficient for the flow of lubricating oil sufficient to push the foreign matter 28 that has entered the lubricating oil passage 10a into the axial groove 24A. It is preferable that the length L2 satisfies the relationship of L2−L1 ≧ 0.5 mm. Further, in order to prevent the lubricating oil from flowing out excessively when the oil groove 17a communicates with the axial groove 24A, the circumferential length L1 of the separation inner peripheral portion 17S ′ and the circumferential direction of the inlet opening 26 The length L2 preferably satisfies the relationship L1 ≧ L2 × 0.3, and more preferably satisfies the relationship L1 ≧ L2 × 0.6. This is because if the circumferential length L1 of the separation inner peripheral portion 17S ′ is too short, the time for the oil groove 17a and the axial groove 24A to communicate with each other becomes longer, and the axial groove 24A extends from the end 17E of the oil groove 17a. This is because the amount of oil flowing into the cylinder, that is, the amount of leakage increases, and the amount of oil sent to the connecting rod bearing 22 decreases.

  The circumferential length (linear distance) L3 of the axial groove 24A on the inner peripheral surface of the main bearing 19 can be 0.2 to 2 mm, and the axial groove 24A from the inner peripheral surface of the main bearing 19 The maximum depth D1 can be 0.1-1 mm, preferably 0.1-0.5 mm (FIG. 7). The circumferential length L3 and the depth D1 of the axial groove 24A may be set to the minimum dimension capable of discharging the foreign matter in view of the size of the foreign matter mixed in the lubricating oil (generally, about 0.1 mm at maximum).

  As described above, when the cross-sectional area of the inlet opening 26 is larger than the cross-sectional area of the lubricating oil passage 10 a and the flow passage transition portions 29 are formed at least on both sides in the circumferential direction of the inlet opening 26, the oil groove 17 a and the axial direction When the groove 24A is communicated, the lubricating oil in the oil groove 17a is guided by the inclined surface of the flow passage transition portion 29 and easily flows into the lubricating oil passage 10a. Therefore, the circumference that pushes the foreign matter 28 toward the axial groove 24A. Directional flow F2 (FIG. 10) can be enhanced. Further, the inclined surface on the front side in the rotational direction of the inlet opening 26 helps the foreign material 28 to enter the axial groove 24A.

  The crankshaft main bearing 19 according to the present invention may have crush reliefs 42 and 44 on the bearing inner peripheral surface adjacent to the joint portion of the semi-cylindrical bearings 17 and 18. As shown in FIG. 13 and FIG. 14, the crush relief has an original inner peripheral surface 40 (main part) in which the thickness of the wall portion is concentric with the center of rotation in the circumferential end region of each semi-cylindrical bearing 17, 18. The relief spaces 42 and 44 are formed by reducing from the arc) in the radial direction, and this may occur, for example, when a pair of semi-cylindrical bearings 17 and 18 are assembled to the journal portion 19 of the crankshaft 10. It is formed to absorb displacement and deformation of the circumferential end face of the cylindrical bearing. Accordingly, the center of curvature of the bearing inner peripheral surface 17S in the region R where the crush relief 42 is formed is different from the center of curvature of the bearing inner peripheral surface (main arc) in other regions (SAE J506 (item 3.26 and Item 6.4), DIN 1497, section 3.2, JIS D3102). In general, in the case of a small internal combustion engine bearing for a passenger car, the depth of the crush relief at the circumferential end surface of the half bearing (distance from the original inner peripheral surface to the actual inner peripheral surface) is 0.01 to 0. .05mm or so.

  The crush relief 42 gradually decreases in depth toward the center in the circumferential direction of the semi-cylindrical bearing 17, and an end portion 42A that defines a region where the crush relief 42 is formed is formed on the bearing inner circumferential surface 17S. However, the end portion 42A may be located on the circumferential center side from the circumferential end portion 17E of the oil groove 17a as shown in FIGS. 13 and 14, or the oil groove 17a as shown in FIG. The circumferential end portion 17E may be located closer to the circumferential end portion. This is because the depth of the crush relief 42 is sufficiently smaller than the depth of the oil groove 17a and the axial groove 24A, and therefore the difference between the original inner peripheral surface 40 and the actual inner peripheral surface 17S 'is the discharge of foreign matter. This is because it does not affect the action. However, when the circumferential end 42A of the crush relief 42 is located on the center side in the circumferential direction from the position of the circumferential end 17E of the oil groove 17a, the outer circumference of the separation inner circumferential portion 17S ′ and the journal portion 10 is obtained. Since the gap formed with the surface slightly increases, the amount of oil flowing from the oil groove 17a to the axial groove 24A, that is, the amount of leakage from the main bearing 19, slightly increases. Therefore, from the viewpoint of reducing the amount of leakage of the lubricating oil, the end 42A of the crush relief 42 is positioned on the circumferential end side of the circumferential end 17E of the oil groove 17a as shown in FIG. preferable.

  In other words, in the case of the semi-cylindrical bearing 17 in which the crush relief 42 shown in FIG. 15 is formed, the inlet opening 26 of the journal portion 10 communicates the oil groove 17a only with the region R in which the crush relief 42 is formed. Even if it has the circumferential length L2, the foreign matter is not discharged and stays at the end of the oil groove 17a. This is because, in addition to the above-described reason that the crush relief 42 is not deep enough to allow foreign matter to enter, the lubricant oil is removed from the crush relief 42 at the initial stage where the inlet opening 26 and the crush relief 42 communicate with each other. This is because the pressure difference between the lubricating oil passage 10a and the crush relief 42 is reduced, and the flow F3 due to the pressure gradient is unlikely to occur, particularly since it flows into the small volume portion and fills it. Therefore, according to the present invention, the inlet opening 26 and the separation inner peripheral surface 17S 'need to be dimensioned so that the oil groove 17a communicates with the axial oil groove 24A or 24B.

  FIG. 16 shows a crankshaft main bearing 19 'according to a second embodiment of the present invention. As can be understood from the drawings, the axial groove is formed only in the joint portion on the right side of the paper surface among the joint portions of the semicylindrical bearings 17 ′ and 18 ′, and the semicylindrical bearing 17 ′ on the upper surface of the paper surface. The oil groove 17a 'formed in the above has the configuration of the present invention described above only on the front side in the rotation direction of the journal portion. That is, the oil groove 17a 'gradually decreases in depth toward the end portion on the front side in the rotation direction, thereby forming a separation inner peripheral surface on the front side in the rotation direction, and on the other hand, a region including the central portion in the circumferential direction A constant depth is maintained from the rear end of the rotation direction to the end of the circumferential direction of the semi-cylindrical bearing 17 ′.

  FIG. 17 shows a crankshaft main bearing 19 ″ according to a third embodiment of the present invention. As can be understood from the drawing, the axial groove is formed on the paper surface of the joint portion of the semicylindrical bearings 17 ″ and 18 ″. The oil groove 17a ″ formed only in the left joint portion and formed in the semi-cylindrical bearing 17 ″ on the upper side of the drawing has the above-described configuration of the present invention only on the rear side in the rotation direction of the journal portion. That is, the oil groove 17a "extends in the circumferential direction so as to gradually reduce the depth from the front end surface in the rotational direction of the semi-cylindrical bearing 17" toward the end on the rear side in the rotational direction, thereby rotating in the rotational direction. A separation inner peripheral surface is formed only on the rear side.

  While the above description has been made with reference to exemplary embodiments, it will be apparent to those skilled in the art that the invention is not limited thereto and that various changes and modifications can be made within the spirit of the invention and the scope of the appended claims. For example, although the oil groove is formed in the upper semi-cylindrical bearing in the above embodiment, it may be formed only in the lower semi-cylindrical bearing. The oil groove may be formed so that the depth is maximum at the center in the circumferential direction of the semi-cylindrical bearing and gradually decreases toward both ends in the circumferential direction of the semi-cylindrical bearing. The cross-sectional shape perpendicular to the direction may be an arbitrary shape such as a semicircular shape or a triangular shape in addition to a rectangle.

10 Journal part 10a Through hole (lubricant oil passage)
12 Crankpin 14 Connecting rod 16 Large end housing 16A Connecting rod side large end housing 16B Cap side large end housing 17 Semi-cylindrical bearing 17a Oil groove 17A Front side circumferential end surface 17B Rear side circumferential end surface 17C, 17D Inclination Surface 17E, 17F Both ends in the circumferential direction of the oil groove 17a 17S Inner peripheral surface 17S 'Separate inner peripheral portion 18 Semi-cylindrical bearing 18A Rear side circumferential end surface 18B Front side circumferential end surface 18D, 18C Inclined surface 19 Main bearing DESCRIPTION OF SYMBOLS 20 Lubricating oil path 22 Connecting rod bearing 22a Semi-cylindrical bearing 22b Semi-cylindrical bearing 24A, 24B Axial groove 26 Inlet opening 28 Foreign object 29 Flow path transition part 42, 44 Crash relief or relief space 42A End

Claims (13)

A crankshaft main bearing for an internal combustion engine for rotatably supporting a journal portion of a crankshaft, wherein the journal portion includes a lubricating oil passage extending therein and the lubrication formed on an outer peripheral surface thereof. In the main bearing having the oil passage inlet opening,
The main bearing is composed of a pair of semi-cylindrical bearings, and only one of the semi-cylindrical bearings has an oil groove formed on an inner peripheral surface thereof;
The oil groove extends in the circumferential direction through at least the circumferential center portion of the one semi-cylindrical bearing, and the center of the width of the oil groove in the axial direction is the center of the inlet opening of the journal portion. The circumferential end of the oil groove does not extend to the circumferential end surface of the one semi-cylindrical bearing, and therefore the circumferential end of the oil groove and the one The inner peripheral surface extends between the end surface in the circumferential direction of the semi-cylindrical bearing and provides a separated inner peripheral surface,
The circumferential end surface where the oil groove of the one semi-cylindrical bearing does not extend, and the circumferential end surface of the other semi-cylindrical bearing joined thereto are inclined surfaces extending over the entire length in the axial direction. Each of the inner circumferential surfaces has an axial groove at the joint of the pair of semi-cylindrical bearings, and the separated inner circumferential surface extends between the axial groove and the oil groove. Further, a circumferential length L1 of the separation inner peripheral surface is made smaller than a circumferential length L2 of the inlet opening of the journal portion, and therefore the oil groove passes through the inlet opening of the lubricating oil passage. A main bearing for a crankshaft of an internal combustion engine capable of communicating with the axial groove. A circumferential length L1 of the separation inner peripheral surface and a circumferential length L2 of the inlet opening of the journal portion are as follows:
L2-L1 ≧ 0.5mm
The main bearing for crankshafts of Claim 1 which satisfy | fills these. A circumferential length L1 of the separation inner peripheral surface and a circumferential length L2 of the inlet opening of the journal portion are as follows:
L1 ≧ L2 × 0.3
The main bearing for crankshafts of Claim 1 or Claim 2 which satisfy | fills these. A circumferential length L1 of the separation inner peripheral surface and a circumferential length L2 of the inlet opening of the journal portion are as follows:
L1 ≧ L2 × 0.6
The main bearing for crankshafts of Claim 3 satisfy | filling these.   The crankshaft main bearing according to claim 1, wherein a depth of the axial groove from an inner peripheral surface of the main bearing is 0.1 to 1 mm.   The crankshaft main bearing according to claim 5, wherein a depth of the axial groove from an inner peripheral surface of the main bearing is 0.1 to 0.5 mm.   The crankshaft main bearing according to claim 1, wherein a circumferential width of the axial oil groove on the inner peripheral surface of the main bearing is 0.2 to 2 mm.   Both circumferential ends of the oil groove do not extend to the respective circumferential end surfaces of the one semi-cylindrical bearing, and therefore the separated inner peripheral surface is provided on both circumferential sides of the oil groove. The crankshaft main bearing according to claim 1.   The main bearing for a crankshaft according to claim 1, wherein a crush relief is formed on an inner peripheral surface side adjacent to each circumferential end surface of the pair of semicylindrical bearings.   10. The crankshaft main body according to claim 9, wherein an end portion of the crush relief on a circumferential center side of the one semicylindrical bearing is located on a circumferential end face side with respect to a circumferential end portion of the oil groove. bearing.   The area of the inlet opening on the outer peripheral surface of the journal part is larger than the cross-sectional area of the lubricating oil passage in the journal part. Therefore, the cross-sectional area gradually changes between the inlet opening and the lubricating oil path. The main bearing for a crankshaft according to claim 1, wherein a road transition portion is formed.   The crankshaft main bearing according to claim 11, wherein a depth dimension of the flow path transition portion from the outer peripheral surface of the journal portion is 1 to 2 mm.   The bearing apparatus comprised from the main bearing for crankshafts of Claim 1, and the said journal part supported by this main bearing.