JP6862318B2 - Main bearing for crankshaft of internal combustion engine - Google Patents

Description

The present invention relates to a main bearing for bearing a crankshaft of an internal combustion engine.

The crankshaft of the internal combustion engine is supported in the journal portion of the crankshaft of the internal combustion engine via a main bearing composed of a pair of half bearings under the cylinder block of the internal combustion engine. For the main bearing, the lubricating oil discharged by the oil pump is formed along the inner peripheral surface of the main bearing through the through hole formed in the wall of the main bearing from the oil gallery formed in the wall of the cylinder block. It is sent into the oil groove. Further, a first lubricating oil passage is formed through the journal portion in the radial direction, and the openings at both ends of the first lubricating oil passage communicate with the oil groove of the main bearing. Further, a second lubricating oil passage passing through the crank arm portion is branched from the first lubricating oil passage of the journal portion, and the second lubricating oil passage is formed to penetrate in the diameter direction of the crank pin. It communicates with the oil passage. In this way, the lubricating oil sent from the oil gallery in the cylinder block wall into the oil groove formed on the inner peripheral surface of the main bearing through the through hole is the first lubricating oil passage, the second lubricating oil passage, and the second lubricating oil passage. It is supplied between the sliding surface of the crank pin and the connecting rod bearing from the discharge port opened at the end of the third lubricating oil passage through the three lubricating oil passages (see, for example, Patent Document 1).

Lubricating oil sent from the oil gallery in the cylinder block wall to the oil groove of the main bearing may be accompanied by residual foreign matter generated during processing of each part, for example. This foreign matter may damage the sliding surface between the journal portion and the main bearing and the sliding surface between the crank pin and the connecting rod bearing, and therefore must be quickly discharged to the outside from the flow of lubricating oil.

Therefore, the circumferential end of the oil groove formed along the inner peripheral surface of one of the pair of half bearings constituting the main bearing is the circumferential end of the inner peripheral surface of the half bearing. A main bearing has been proposed in which foreign matter that has entered the oil groove is discharged to the outside of the main bearing through a gap in the crash relief portion or an axial groove by communicating with the crash relief portion and the axial groove formed in the above. (Patent Documents 2 and 3).

The crash relief is a gap region formed between the bearing shaft and the bearing shaft by forming the wall thickness of the region adjacent to the circumferential end face of the half bearing so as to become thinner toward the circumferential end face. (See, for example, SAE J506 (item 3.26 and item 6.4), DIN1497 (section 3.2), JIS D3102), misalignment of the butt surface of the half bearing in the state where a pair of half bearings are assembled. It is formed by planning to absorb deformation (see, for example, Patent Document 2).

Regarding the supply of lubricating oil to the plain bearings for internal combustion engines, first, the lubricating oil is supplied from the outside of the main bearing for the crankshaft journal portion into the oil groove formed on the inner surface of the main bearing, and the lubricating oil is supplied for the crankshaft journal portion. It is supplied to the sliding surface of the main bearing and the sliding surface of the crank pin conrod bearing.
When the internal combustion engine is in operation, foreign matter remaining in the lubricating oil passage tends to be mixed in the lubricating oil supplied to the oil groove of the main bearing for the crankshaft journal portion. The foreign matter means metal processing waste when the oil passage is cut, casting sand at the time of casting, and the like. This foreign matter accompanies the flow of lubricating oil due to the rotation of the crankshaft, and in the conventional main bearing for internal combustion engines, crash relief and axial direction formed in the bearing circumferential end region on the front side in the rotation direction of the crankshaft. It is discharged together with the lubricating oil through the groove.
However, foreign matter that has entered the oil groove together with the lubricating oil through the through hole formed in the wall of the bearing reaches the first lubricating oil passage of the journal part before reaching the crash relief or the axial groove in the peripheral end region of the bearing. Many of them enter the first lubricating oil passage together with the lubricating oil from the inlet opening of the bearing. A part of the foreign matter that has entered the first lubricating oil passage flows back into the oil groove together with the lubricating oil, so that it is difficult to be discharged to the outside of the bearing at an early stage.

More specifically, FIGS. 16A and 16B and 17A and 17B will be used to describe the operation of the prior art. As shown in FIGS. 16A and 16B, while the inlet opening 6c of the lubricating oil passage 6a on the surface of the journal portion 6 is located on the main cylindrical surface 171 of the lower half bearing 142, the surface and half of the journal portion 6 Since the gap between the split bearing 142 and the main cylindrical surface 171 is narrow, the inlet opening 6c is closed to the main cylindrical surface 171 of the half bearing 142, and the inside of the lubricating oil passage 6a is affected by the centrifugal force due to the rotation of the crankshaft. The pressure of the lubricating oil near the inlet opening 6c is extremely high.

As shown in FIGS. 17A and 17B, the pressure of the lubricating oil inside the lubricating oil passage 6a and the crash relief 170 at the moment when the inlet opening 6c of the lubricating oil passage 6a on the surface of the journal portion 6 and the crash relief 170 start to communicate with each other. Due to the difference from the pressure of the lubricating oil in the gap (relief gap) between the surfaces of the journal portion 6 and the surface of the journal portion 6, an oil jet flow (backflow) from the lubricating oil passage 6a to the relief gap side is momentarily formed. Will be done.

At that time, the foreign matter F that has entered the relief gap together with the oil injection flow travels straight through the relief gap, passes through the axial groove 177 due to inertial force, and enters the oil groove 141 g of the other half bearing 141. .. Therefore, in the conventional main bearing, it is difficult for foreign matter to be discharged to the outside of the bearing at an early stage.

Japanese Unexamined Patent Publication No. 8-277831 Japanese Unexamined Patent Publication No. 4-219521 Japanese Unexamined Patent Publication No. 2005-69283

An object of the present invention is to provide a main bearing for a crank of an internal combustion engine having excellent foreign matter discharging property.

In order to achieve the above object, according to one aspect of the present invention,
At least one of the journal portion of the crankshaft of the internal combustion engine, the cylindrical body portion, the lubricating oil passage extending through the cylindrical body portion, and the lubricating oil passage formed on the outer peripheral surface of the cylindrical body portion. A main bearing for rotatably supporting a journal portion having two inlet openings.
The main bearing has first and second half bearings that are combined into a cylindrical shape by abutting the end faces in the circumferential direction.
When combined, the first and second half-split bearings are configured to together form an axial groove extending over the entire axial direction of the main bearing on the inner peripheral surface side of each butt portion. ,
The first and second halves of the half bearing have a main cylindrical portion including the central portion in the circumferential direction of the halved bearing and both ends of the halved bearing in the circumferential direction so that the wall thickness is thinner than that of the main cylindrical portion. Has a crush relief portion formed over the entire length in the axial direction.
An oil groove is formed on the inner peripheral surface of the first half-split bearing, and the peripheral end of the oil groove on the rear side in the rotation direction of the crankshaft is the rotation of the crankshaft of the first half-split bearing. It is located in the crash relief portion on the rear side in the direction, and the circumferential end on the front side in the rotation direction of the crankshaft is located in the crash relief portion on the front side in the rotation direction of the crankshaft, or the first An opening is made in the circumferential end face on the front side in the rotational direction of the crankshaft of the half-split bearing.
A partial groove is formed on the inner peripheral surface of the second half-split bearing, and the partial groove is the circumference of the two circumferential end faces of the second half-split bearing on the front side in the rotational direction of the crankshaft. Open only on the directional end face,
The center of the groove width of the oil groove and the partial groove are aligned with each other,
The opening of the partial groove in the circumferential end face on the front side in the rotational direction of the crankshaft of the second half bearing is shielded by the circumferential end face on the rear side in the rotational direction of the crankshaft of the first half bearing. A main bearing characterized by being provided is provided.

In the above main bearing, preferably
The partial groove has an inscribed angle θ1 from the circumferential end face of the second half bearing on the front side in the rotational direction of the crank shaft (however, the minimum value of the inscribed angle θ1 = 5 °, the inscribed angle θ1). It is formed in the range of maximum value = 45 °).

In the above main bearing, preferably
The circumferential end of the oil groove on the rear side of the crankshaft in the rotational direction has an inscribed angle θ2 (however, the inscribed angle) from the circumferential end face on the rear side of the crankshaft of the first half bearing in the rotational direction. It is located in the range of the minimum value of θ2 = 2 ° and the maximum value of the inscribed angle θ2 = 7 °).

In the above main bearing, preferably
The groove depth (D2) at the circumferential end face on the front side in the rotational direction of the crankshaft of the second half bearing of the partial groove is 0.3 to 1.5 mm.

In the above main bearing, preferably
The groove width (W2) of the partial groove on the circumferential end surface of the second half bearing of the partial groove on the front side in the rotational direction of the crankshaft is the circumferential direction on the rear side of the crankshaft of the oil groove in the rotational direction. It is larger than the groove width (W1) at the end position.

(1) According to the present invention, the main bearing has first and second half-split bearings, and oil to which lubricating oil is supplied from the outside of the main bearing to the inner peripheral surface of the first half-split bearing. A groove is formed, and both ends in the circumferential direction of the oil groove are located at the crash relief of the first half-split bearing, and the two circumferences of the second half-split bearing are on the inner peripheral surface of the second half-split bearing. Of the directional end faces, a partial groove is formed that opens only on the circumferential end face on the front side in the rotation direction of the crankshaft.
As shown in FIGS. 14A and 14B, also in the present invention, the inlet opening 6c of the lubricating oil passage 6a on the surface of the journal portion 6 is located on the main cylindrical surface 71 (inner surface of the main cylindrical portion) of the second half bearing 42. While the inlet opening 6c is closed by the main cylindrical surface 71 of the second half bearing 42, the lubricating oil in the lubricating oil passage 6a is on the inlet opening 6c side due to the centrifugal force due to the rotation of the crankshaft. The pressure of the lubricating oil in the vicinity of the inlet opening 6c in the lubricating oil passage 6a is extremely high, particularly when the rotation speed of the crankshaft is high during the operation of the internal combustion engine.
As shown in FIGS. 15A and 15B, at the moment when the inlet opening 6c of the lubricating oil passage 6a on the surface of the journal portion 6 and the partial groove 42g of the second half bearing 42 start communication, the inside of the lubricating oil passage 6a Due to the difference between the pressure of the lubricating oil and the pressure of the lubricating oil in the partial groove 42g, a high-pressure lubricating oil jet flow that momentarily ejects from the lubricating oil passage 6a into the partial groove 42g and flows back is formed. The foreign matter F mixed in the lubricating oil passage 6a enters the partial groove 42g by the jet flow of the lubricating oil. The foreign matter F that has entered the partial groove 42g flows toward the opening of the partial groove 42g. At this time, the foreign matter F having a higher specific gravity than the lubricating oil flows along the bottom surface of the partial groove 42 due to the action of centrifugal force.

The groove width centers of the oil groove 41 g and the partial groove 42 g are aligned with each other. In the oil groove 41g, the circumferential end 43 on the rear side in the rotation direction of the crankshaft is located at the rear side crash relief portion 70 in the rotation direction of the crankshaft of the first half bearing 41, and the partial groove 42g is the first. The half-split bearing 42 of 2 is open only on the circumferential end surface 72 on the front side in the rotational direction of the crankshaft, and the oil groove 41 g and the partial groove 42 g are not in a relationship of fluid communication with each other. In this structure, the openings of the partial grooves 42g located on the two circumferential end faces 72 in contact with each other are closed by the circumferential end faces 72 of the first half bearing 41 having the oil groove 41 g. Therefore, the shielding structure of the opening serves as a barrier against the foreign matter F moving to the opening along the groove bottom of the partial groove 42g, the circumferential movement speed of the foreign matter F decreases, and the inertial force of the linear motion of the foreign matter F increases. descend.
On the other hand, it is located on the inner peripheral surface side of the bearing of the circumferential end surface 72 along the butt contact interface between the circumferential end surface 72 of the first half bearing 41 and the circumferential end surface 72 of the second half bearing 42. Inclined surfaces 76 are formed on the two square edges, and an axial groove 77 is formed over the entire axial width of the main bearing 4. Due to this structure, the foreign matter F having a reduced circumferential moving speed is likely to accompany the partial groove 42g and the lubricating oil flowing along the axial groove 77 communicating with the partial groove 42g, and the foreign matter F is attached to the main bearing 1 together with the lubricating oil. It is discharged smoothly from the end in the axial direction.

As for the axial groove 77, if the cross-sectional area is made excessive, the amount of lubricating oil leaked increases. Therefore, it is preferable to make the cross-sectional area as small as possible as long as the foreign matter F is discharged. Specifically, in the case of a small internal combustion engine mounted on a passenger car or the like, it is preferable that the groove width of the axial groove 77 is 0.2 mm to 1 mm and the groove depth is 0.2 mm to 1 mm. However, the width and depth of the oil groove are determined by the specifications of the internal combustion engine and are not limited to these dimensions.

(2) The foreign matter F, which has a higher specific gravity than the lubricating oil, follows the groove bottom by the action of centrifugal force while moving in the partial groove 42 g to the fluid communication portion. Therefore, the amount of foreign matter in the lubricating oil flowing through the upper region of the partial groove 42 g (the upper region on the side closer to the crankshaft, not the lower region near the groove bottom) is small (see FIG. 5). Lubricating oil with a small amount of foreign matter flowing in the upper region of the partial groove 42g is provided on the surface of the crash relief portion 70 of the second half bearing 42, the surface of the crash relief portion 70 of the first half bearing 41, and the crankshaft. Since the lubricating oil flows straight through the gap between the journal portion 6 and the surface of the journal portion 6 in the circumferential direction and smoothly flows into the oil groove 41 g, the amount of lubricating oil leaking from the main bearing 4 can be reduced.
As described above, in the oil groove 41g, the circumferential end 43 on the rear side in the rotation direction of the crankshaft is located at the rear side crash relief portion 70 in the rotation direction of the crankshaft of the first half bearing 41, and the partial groove 42g Is a case where the second half bearing 42 is opened only on the circumferential end surface 72 on the front side in the rotational direction of the crankshaft, and the oil groove 41 g and the partial groove 42 g are not in a fluid communication relationship with each other. When the oil groove 41g and the partial groove 42g are in a fluid communication relationship with each other, the foreign matter F moving along the groove bottom surface of the partial groove 42g is likely to be sent into the oil groove 41g. Further, even when the oil groove 41g and the partial groove 42g do not have a fluid communication relationship with each other, unlike the main bearing 4 of the present invention, when the axial groove 77 for fluid communication does not exist in the partial groove 42g. Is easy to send the foreign matter F that has reached the opening (open groove end) of the partial groove 42g into the oil groove 41g of the first half bearing 41. Further, when the circumferential end 43 of the oil groove 41g of the first half bearing 41 on the rear side in the rotation direction of the crankshaft is open to the main cylindrical surface 71 of the first half bearing 41 or oil. When the groove width centers of the groove 41g and the partial groove 42g are not aligned with each other, the lubricating oil having a small amount of foreign matter flowing in the upper region of the partial groove 42g does not flow smoothly into the oil groove 41g or is difficult to flow. Therefore, the amount of lubricating oil leaking from the main bearing 4 increases.

(3) The main bearing 4 of the present invention has a structure in which the opening (open groove end) of the partial groove 42 g is closed by the circumferential end surface 72 of the first half bearing 41 having the oil groove 41 g. The structure exerts a blocking effect against foreign matter rolling to the opening (open groove end) along the groove bottom of the partial groove 42 g. In order to maximize this blocking effect, it is preferable to make the groove bottom a flat surface so that the groove bottom width of the partial groove 42 g is sufficiently large.

(4) As a preferred embodiment of the present invention, the partial groove 42 g is from the circumferential end surface 72 on the front side in the rotational direction of the crankshaft of the second half bearing 42 to the central portion side in the circumferential direction of the second half bearing 42. A case where the bearing is formed in the range of the inscribed angle θ1 (however, the minimum value of the inscribed angle θ1 = 5 ° and the maximum value of the inscribed angle θ1 = 45 °) will be described.
When the inscribed angle θ1 is set to 5 ° or more, a sufficient length of the partial groove 42 g is secured, and the foreign matter F that has entered the partial groove 42 g together with the injection flow of the lubricating oil reaches the fluid communication portion. The circumferential movement speed tends to decrease. Therefore, the foreign matter F is easily discharged to the outside of the bearing by the axial groove 77 of the fluid communication portion. When the inscribed angle θ1 is set to less than 5 °, this effect is insufficient, and foreign matter F often passes through the axial groove 77 and enters the oil groove 41g of the first half bearing 41. ..
The reason why the maximum value of the inscribed angle θ1 is set to 45 ° is that the main load receiving portion of the second half-split bearing 42 having the partial groove 42 g (the center in the circumferential direction of the half-split bearing 42 on which a large load acts from the crankshaft). This is to avoid the region) and form a partial groove 42 g to secure the strength of the second half bearing 42 against a large acting load.

(5) As a preferred embodiment of the present invention, the circumferential end 43 on the rear side of the crankshaft of the oil groove 41 g in the rotational direction is the circumferential end surface of the first half bearing 41 on the rear side of the crankshaft in the rotational direction. A case where the vehicle is located in the range from 72 to the inscribed angle θ2 (however, the minimum value of the inscribed angle θ2 = 2 ° and the maximum value of the inscribed angle θ2 = 7 °) will be described.
When the inscribed angle θ2 is set to 2 ° or more, the circumferential end 43 of the oil groove 41g on the rear side in the rotational direction of the crankshaft and the opening of the partial groove 42g are sufficiently separated from each other, and foreign matter flowing through the partial groove 42g. Is hard to invade the oil groove 41g. If the inscribed angle θ2 is less than 2 °, foreign matter flowing through the partial groove 42g may invade the oil groove 41g.
Further, when the inscribed angle θ2 is set to 7 ° or less, the lubricating oil having a small amount of foreign matter flowing in the upper region of the partial groove 42g can easily flow smoothly into the oil groove 41g. When the inscribed angle θ2 exceeds 7 °, it may be difficult for the lubricating oil having a small amount of foreign matter flowing in the upper region of the partial groove 42g to flow into the oil groove 41g.

(6) As a preferred embodiment of the present invention, the groove depth (D2) at the circumferential end surface 72 on the front side in the rotational direction of the crankshaft of the second half bearing 42 having the partial groove 42 g is 0.3 to 1. It is 5 mm. When the groove depth (D2) is less than 0.3 mm, foreign matter that should flow on the bottom surface side of the partial groove 42g also mixes with the oil flowing in the upper region of the partial groove 42g and easily penetrates into the oil groove 41g. Become. Further, when the groove depth (D2) exceeds 1.5 mm, the groove depth is too deep and foreign matter flowing on the groove bottom surface side of the partial groove 42 g becomes difficult to enter the axial groove 77, which is the main cause. It becomes difficult for the bearing 4 to be discharged to the outside.

(7) As a preferred embodiment of the present invention, the groove width (W2) at the circumferential end surface 72 on the front side in the rotational direction of the crankshaft of the second half bearing 42 having the partial groove 42g is the same as that of the crankshaft of the oil groove 41g. It will be described that a configuration larger than the groove width (W1) at the position of the circumferential end 43 on the rear side in the rotation direction is adopted.
As shown in FIG. 9, the foreign matter F that has entered the partial groove 42g tends to flow in the vicinity of both ends in the axial direction in the partial groove 42g until it reaches the fluid communication portion. Even if the foreign matter F crosses the axial groove 77 and enters the first half-split bearing 41 side, the end face in the circumferential direction on the front side of the crankshaft of the second half-split bearing 42 in the rotational direction. When the groove width (W2) of the partial groove 42g in 72 is larger than the groove width (W1) at the position of the circumferential end 43 on the rear side in the rotation direction of the crankshaft of the oil groove 41g, the foreign matter F is present. , It is difficult to enter the oil groove 41g of the first first half bearing 41.

The schematic diagram which cut the crankshaft of an internal combustion engine by a journal part and a crankpin part respectively. The front view of the main bearing which concerns on Example 1 of this invention. FIG. 2 is a plan view of the inner peripheral surface of the first half bearing of the main bearing shown in FIG. 2. The plan view which looked at the inner peripheral surface of the 2nd half bearing of the main bearing shown in FIG. The functional explanatory view of the main bearing shown in FIG. 2 is a view showing the end face in the circumferential direction of the second half bearing of the main bearing shown in FIGS. 2 to 4 (FIG. VII arrow view in FIG. 5). The plan view which looked at the inner peripheral surface of the 1st half bearing of the main bearing which concerns on Example 2 of this invention. The plan view which looked at the inner peripheral surface of the 2nd half bearing of the main bearing which concerns on Example 2. FIG. Functional explanatory view of the main bearing shown in FIGS. 7 and 8. The front view of the main bearing which concerns on Example 3 of this invention. FIG. 10 is a plan view of the inner peripheral surface of the first half bearing of the main bearing shown in FIG. FIG. 10 is a plan view of the inner peripheral surface of the second half bearing of the main bearing shown in FIG. The figure which shows an example of the groove cross-sectional shape of the oil groove and the partial groove formed in the main bearing of this invention. The figure seen from the inside of the bearing for demonstrating the operation of the main bearing of this invention. The front view for demonstrating the operation of the main bearing of this invention. The figure seen from the inside of the bearing for demonstrating the operation of the main bearing of this invention. The front view for demonstrating the operation of the main bearing of this invention. The figure seen from the inside of the bearing which explained the operation of the main bearing of the prior art. The front view explaining the operation of the main bearing of the prior art. The figure seen from the inside of the bearing which explained the operation of the main bearing of the prior art. The front view explaining the operation of the main bearing of the prior art.

(Overall configuration of bearing device)
As shown in FIG. 1, the bearing device 1 of the present embodiment has a journal portion 6 supported at the lower part of the cylinder block 8 and a crank pin 5 formed integrally with the journal portion 6 and rotating around the journal portion 6. And a connecting rod 2 that transmits reciprocating motion from the internal combustion engine to the crank pin 5. The bearing device 1 further includes a main bearing 4 that rotatably supports the journal portion 6 and a conrod bearing 3 that rotatably supports the crankpin 5 as a slide bearing that supports the crankshaft.

The crankshaft has a plurality of journal portions 6 and a plurality of crank pins 5, but here, for convenience of explanation, one journal portion 6 and one crank pin 5 will be illustrated and described. In FIG. 1, as for the positional relationship in the depth direction of the paper surface, the journal portion 6 is on the back side of the paper surface and the crank pin 5 is on the front side.

The journal portion 6 is pivotally supported by the lower portion 81 of the cylinder block of the internal combustion engine via a main bearing 4 composed of a pair of half bearings 41 and 42. In FIG. 1, the upper first half-split bearing 41 attached to the lower part of the cylinder block has an oil groove 41 g formed in the circumferential direction on the inner peripheral surface, and the lower second half-split bearing attached to the bearing cap 82 is attached. A partial groove 42g is formed on the inner peripheral surface of the bearing 42. Further, the journal portion 6 has a lubricating oil passage 6a penetrating in the radial direction, and when the journal portion 6 rotates in the direction of the arrow X, the inlet openings 6c at both ends of the lubricating oil passage 6a alternate with the oil grooves of the main bearing 4. It communicates with 41g.

The crank pin 5 is attached to the large end housing 21 of the connecting rod 2 (the large end housing 22 on the rod side and the large end housing 23 on the cap side) via the connecting rod bearing 3 composed of a pair of half bearings 31 and 32. It is bearing.

As described above, the lubricating oil discharged by the oil pump to the main bearing 4 is divided into the first half through the through hole formed in the wall of the main bearing 4 from the oil gallery formed in the cylinder block wall. It is fed into the oil groove 41g formed along the inner peripheral surface of the bearing 41.

Further, the first lubricating oil passage 6a is formed through the journal portion 6 in the radial direction, and the inlet opening 6c of the first lubricating oil passage 6a communicates with the oil groove 41g. Then, a second lubricating oil passage 5a that branches from the first lubricating oil passage 6a of the journal portion 6 and passes through the crank arm portion (not shown) is formed, and the second lubricating oil passage 5a is formed by the crank pin 5. It communicates with a third lubricating oil passage 5b formed through the diameter direction of the above.

In this way, the lubricating oil passes through the first lubricating oil passage 6a, the second lubricating oil passage 5a, and the third lubricating oil passage 5b, and from the discharge port 5c at the end of the third lubricating oil passage 5b. , It is supplied to the gap formed between the crank pin 5 and the connecting rod bearing 3.

(Composition of half-split bearing)
The main bearing 4 of this embodiment is formed by abutting the end faces of the pair of half bearings 41 and 42 in the circumferential direction and combining them into a cylindrical shape as a whole. As shown in FIG. 2, each half-split bearing 41 (or 42) is formed in a semi-cylindrical shape by bimetal in which a bearing alloy is thinly adhered on a steel plate. The half-split bearings 41 and 42 include a main cylindrical portion 71 formed including a central portion in the circumferential direction, and crash relief portions 70 and 70 formed at both end portions in the circumferential direction.

The crush relief portion 70 is a center of curvature different from the center of curvature of the inner peripheral surface of the bearing, which is formed by removing the bearing wall of the half-split bearings 41 and 42 near the end faces in the circumferential direction on the inner peripheral surface side. The thickening region (refers to the region whose thickness is reduced toward the end face in the circumferential direction, as specified in SAE J506 (see item 3.26, item 6.4), DIN1497, §3.2). means.

2 to 4 show a main bearing 4 for a crank journal 6 composed of a first half-split bearing 41 and a second half-split bearing 42. The main bearing 4 is formed by abutting the peripheral end faces 72 of the pair of half bearings 41 and 42 and combining them into a cylindrical shape as a whole (see FIG. 2). The oil groove 41g is formed from the crash relief portion 70 on the front side in the rotation direction of the crankshaft (see arrow X) of the first half bearing 41 to the crash relief portion 70 on the rear side in the rotation direction of the crankshaft. Has been done. Therefore, the oil groove 41g has an opening (open groove end) in both crash relief portions 70. The circumferential end 43 of the oil groove 41g on the rear side of the crankshaft in the rotation direction has an inscribed angle θ2 from the circumferential end surface 72 on the rear side of the crankshaft of the first half bearing 41 in the rotation direction (however, , The minimum value of the inscribed angle θ2 = 2 °, the maximum value of the inscribed angle θ2 = 7 °). Further, the bottom of the oil groove 41g is flat.
Further, the square edge portion located inside the circumferential end surface 72 of the first half bearing 41 (on the axial side of the main bearing 4) is chamfered over the entire bearing width direction to form an inclined surface 76. It has become.

The inner peripheral surface of the second half bearing 42 has a short circumferential length within the range of the inscribed angle θ1 measured from the circumferential end surface 72 on the front side in the rotation direction of the crankshaft (see arrow X). 42g of partial grooves are formed. The groove width center of the partial groove 42 g and the groove width center of the oil groove 41 g are aligned with each other. The bottom of the partial groove 42 g is flat as shown in FIG.
The circumferential end of the partial groove 42 g of the second half bearing 42 (the end of the half bearing 42 on the circumferential central side) is the inner peripheral surface of the main cylindrical portion 71 as shown in FIG. 4 and the like. However, the present invention is not limited to this, and the circumferential end portion of the partial groove 42 g may be located at the crash relief portion 70.
Further, the square edge portion located inside the circumferential end surface 72 of the second half bearing 42 (on the axial side of the main bearing 4) is chamfered over the entire bearing width direction to form an inclined surface 76. It has become.
The inclined surface 76 of the second half bearing 41 is paired with the inclined surface 76 of the first half bearing 41 and extends in the axial direction of the V-shaped cross section extending over the entire axial width of the main bearing 4. The groove 77 is defined.

With the above configuration, in the circumferential end faces 72 and 72 of the first half-split bearing 41 and the second half-split bearing 42 that are in contact with each other, the oil groove 41 g and the partial groove 42 g do not communicate with each other, and the partial groove does not communicate with each other. The 42 g and the axial groove 77 communicate with each other in fluid.

Dimensional relationship between oil groove 41g and partial groove 42g Groove width of oil groove 41g and partial groove 42g: Groove widths W1 and W2 of both grooves 41g and 42g are equal to each other (W1 = W2) (see FIGS. 3 and 4).

According to such a configuration of the first half-split bearing 41 and the second half-split bearing 42, the oil groove 41 g and the partial groove 42 g are not in a fluid communication state at the abutted circumferential end faces 72 and 72. The opening (open groove end) of the partial groove 42 g is shielded by the circumferential end surface 72 of the first half bearing 41. Due to this shielding action, the moving speed of the foreign matter F moving along the groove bottom of the partial groove 42g gradually decreases as it approaches the peripheral end surface 72. Due to the decrease in the linear inertial force of the foreign matter F in the circumferential direction at the abutted circumferential end faces 72 and 72, the foreign matter F accompanies the lubricating oil flowing from the partial groove 42g to the axial groove 77, and the foreign matter F is the axis of the main bearing 4. It is easily discharged to the outside of the bearing from the directional end.
On the other hand, although the amount of foreign matter in the lubricating oil flowing in the groove upper region away from the groove bottom of the partial groove 42 g is small, the lubricating oil flows to the crash relief 70 and the oil groove 41 g of the first half bearing 41. The outflow of lubricating oil from the main bearing 4 can be suppressed.

The second embodiment shown in FIGS. 7 to 9 will be described. Example 2 has the same configuration as that of Example 1 except for a part. Hereinafter, only the differences will be described.
The groove width (W2) of the partial groove in the circumferential end surface 72 on the front side in the rotational direction of the crankshaft of the second half bearing 42 of the partial groove 42 g is the circumference on the rear side in the rotational direction of the crankshaft of the oil groove 41 g. It is larger than the groove width (W1) at the position of the directional end 43.
A preferable relationship between W1 and W2 is 1.1 × W1 <W2 <2 × W1.

As shown in FIG. 9, the foreign matter F that has entered the partial groove 42g tends to flow in the vicinity of both ends in the axial direction in the partial groove 42g until it reaches the fluid communication portion. Even if the foreign matter F crosses the axial groove 77 and enters the first half-split bearing 41 side, the end face in the circumferential direction on the front side of the crankshaft of the second half-split bearing 42 in the rotational direction. When the groove width (W2) of the partial groove 42g in 72 is larger than the groove width (W1) at the position of the circumferential end 43 on the rear side in the rotation direction of the crankshaft of the oil groove 41g, the foreign matter F is present. , It is difficult to enter the oil groove 41g of the first first half bearing 41.

The main bearing 4 shown in FIGS. 10 to 12 includes a first half-split bearing 41 and a second half-split bearing 42. The second half-split bearing 42 is the same product as the second half-split bearing 42 in the first embodiment. The first half-split bearing 41 is different from the first half-split bearing 41 in the first embodiment in the following points. The groove depth of the oil groove 41g is the minimum at the circumferential end 43 on the rear side in the rotation direction (arrow X direction) of the crankshaft of the first half bearing 41, and is the circumference on the front side in the rotation direction of the crankshaft. It gradually increases toward the directional end face 72. The groove depth of the oil groove 41g in the crash relief portion 70 means a groove depth based on the inner peripheral surface of the virtual main cylindrical portion 71 when the crash relief is not formed. Then, as in the case of the first embodiment, the groove width (W1) of the oil groove 41 g and the groove width (W2) of the partial groove 42 g are made equal to each other (W1 = W2).

In the above embodiment, the cross-sectional shapes of the oil groove 41 g and the partial groove 42 g are inverted trapezoidal as shown in FIG. 13, that is, both side surfaces are inclined surfaces, and the groove top width is made larger than the groove bottom width. You may. However, the groove widths (W1, W2) of the oil groove 41 g and the partial groove 42 g in this case are values measured at the groove bottom.
Further, in Examples 1 and 2, the groove depth of the oil groove 41 g is gradually reduced from the central portion in the circumferential direction of the first half bearing 41 toward both end faces 72 in the circumferential direction. The main bearing is not limited to this, and for example, the depth of the oil groove 41 g may be formed to be constant at the central portion in the circumferential direction of the first half bearing 41.

In Examples 1 to 3, a partial groove similar to the partial groove 42 g is provided on the circumferential end surface 72 side of the crankshaft of the second half bearing 42 on the rear side in the rotational direction, and the second half split bearing 42 is split. The bearing 42 may have a symmetrical shape. By adopting such a symmetrical shape, it is possible to prevent erroneous assembly work of the main bearing 4 in advance. Further, another partial groove having a shape and size different from that of the partial groove 42g may be formed on the circumferential end surface 72 side of the second half bearing 42 on the rear side in the rotation direction of the crankshaft.

2 Connecting rod 3 Connecting rod bearing 4 Main bearing 5 Crank pin 5a, 5b Lubricating oil passage 5c Discharge port 6 Journal part 6a Lubricating oil passage 6c Inlet opening 41, 42 Half bearing 41g Oil groove 42g Partial groove 43 Circumferential end 70 Crash relief Part 71 Main cylindrical part 72 Circumferential end face 77 Axial direction groove F Foreign matter

Claims (5)

At least one of the journal portion of the crankshaft of the internal combustion engine, the cylindrical body portion, the lubricating oil passage extending through the cylindrical body portion, and the lubricating oil passage formed on the outer peripheral surface of the cylindrical body portion. A main bearing for rotatably supporting a journal portion having two inlet openings.
The main bearing has first and second half bearings that are combined into a cylindrical shape by abutting the end faces in the circumferential direction.
When combined, the first and second half-split bearings are configured to together form an axial groove extending over the entire axial direction of the main bearing on the inner peripheral surface side of each butt portion. ,
The first and second halves of the half bearing have a main cylindrical portion including the central portion in the circumferential direction of the halved bearing and both ends of the halved bearing in the circumferential direction so that the wall thickness is thinner than that of the main cylindrical portion. Has a crush relief portion formed over the entire length in the axial direction.
An oil groove is formed on the inner peripheral surface of the first half-split bearing, and the peripheral end of the oil groove on the rear side in the rotation direction of the crankshaft is the rotation of the crankshaft of the first half-split bearing. It is located in the crash relief portion on the rear side in the direction, and the circumferential end on the front side in the rotation direction of the crankshaft is located in the crash relief portion on the front side in the rotation direction of the crankshaft, or the first An opening is made in the circumferential end face on the front side in the rotational direction of the crankshaft of the half-split bearing.
A partial groove is formed on the inner peripheral surface of the second half-split bearing, and the partial groove is the circumference of the two circumferential end faces of the second half-split bearing on the front side in the rotational direction of the crankshaft. Open only on the directional end face,
The groove width centers of the oil groove and the partial groove are aligned with each other, and the opening of the partial groove on the circumferential end surface on the front side in the rotational direction of the crankshaft of the second half bearing is the first half split. A main bearing characterized in that it is shielded by a circumferential end face on the rear side in the rotational direction of the crankshaft of the bearing. The partial groove has an inscribed angle θ1 from the circumferential end surface of the second half bearing on the front side in the rotational direction of the crank shaft (however, the minimum value of the inscribed angle θ1 = 5 °, the inscribed angle θ1). The main bearing according to claim 1, wherein the main bearing is formed in a range of (maximum value = 45 °). The circumferential end of the oil groove on the rear side of the crankshaft in the rotational direction has an inscribed angle θ2 (however, the inscribed angle) from the circumferential end face on the rear side of the crankshaft of the first half bearing in the rotational direction. The main bearing according to claim 1 or 2, wherein the main bearing is located in the range (minimum value of θ2 = 2 °, maximum value of inscribed angle θ2 = 7 °). From claim 1, the groove depth (D2) at the circumferential end face on the front side in the rotational direction of the crankshaft of the second half bearing of the partial groove is 0.3 to 1.5 mm. The main bearing according to any one of claims 3. The groove width (W2) of the partial groove on the circumferential end surface of the second half bearing of the partial groove on the front side in the rotational direction of the crankshaft is the circumferential direction on the rear side in the rotational direction of the crankshaft of the oil groove. The main bearing according to any one of claims 1 to 4, wherein the main bearing is larger than the groove width (W1) at the position of the end portion.

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