JPH08312633A - Crankshaft bearing - Google Patents

Abstract

PURPOSE: To restrain increase of friction and increase of clearance between a crankshaft and a bearing metal generated due to slant of the crankshaft by increase of belt tension in the hot state by fitting a means slanting the crankshaft bearing to a journal cap. CONSTITUTION: One end of a slanting means 17 is to a journal cap 14 of a #1 crankshaft bearing 10 and the other end is to a cylinder block 12 respectively fitted, and hence in the hot state of an engine the ξ1 crankshaft bearing 10 is pushed forward against the cylinder block 12 and slanted. Because the cylinder block 12 can sufficiently receive reaction from the slanting means, the slanting means 17 can sufficiently slant the #1 crankshaft bearing 10. Because the slanting means 17 is made of a material of coefficient of thermal expansion equal to or nearly equal to that of a cylinder head, the slanting means 17 slants the #1 crankshaft bearing 10 corresponding to belt tension increasing in response to thermal expansion of the cylinder head, and hence increase of friction and increase of clearance in the #1 crankshaft bearing 10 can be restrained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crankshaft journal bearing structure for an internal combustion engine.

[0002]

2. Description of the Related Art In an internal combustion engine in which a cylinder head is made of an aluminum alloy and a cylinder block is made of cast iron,
During engine warming, the belt tension rises due to the relatively large thermal expansion of the cylinder head, and the tip of the crankshaft is lifted by the belt, and the crankshaft has a minute amount relative to the crankshaft journal bearing (especially the # 1 bearing on the tip side). Inclination, at this time, the bearing friction between the crankshaft and the bearing metal becomes large on the crankshaft lifting side, and the clearance between the crankshaft and the bearing metal becomes large on the opposite side to the crankshaft lifting side, resulting in impact during the engine explosion process. It is known that the sound becomes loud. In order to suppress this, according to Japanese Utility Model Laid-Open No. 62-86412, the bearing metal of the crankshaft # 1 bearing is brought into spherical contact with the block-side bearing portion and the journal cap on the metal back surface, and the bearing metal is used for the inclination of the crankshaft. A crankshaft bearing structure has been proposed in which the crankshaft bearing structure is made to follow and become movable, thereby suppressing an increase in bearing friction and an increase in clearance between the crankshaft and the bearing metal when the crankshaft is tilted.

[0003]

However, in a crankshaft bearing in which the bearing metal is movable with respect to the cap, fretting occurs on the sliding surface between the bearing metal and the journal cap, and the durability of the cap deteriorates. Further, when the bearing metal moves, stress is generated on the mating surface of the bearing metal that is split in two in the circumferential direction, and deformation may occur at that portion, causing bearing seizure. In order to prevent this, if the bearing metal is not movable and the bearing metal is tilted from the beginning to the extent that it occurs during warming, the bearing friction will be increased when the belt tension before warming up is small. I will end up. An object of the present invention is to increase the friction between the crankshaft and the bearing metal caused by the inclination of the crankshaft due to the increase in belt tension during warming without causing fretting between the bearing metal and the journal cap. It is intended to provide a crankshaft bearing that can suppress an increase in clearance.

[0004]

The crankshaft bearing of the present invention which achieves the above object is as follows. (1) A block-side bearing portion formed on a cylinder block, a journal cap that is bolted to the block-side bearing portion, and a cylindrical surface rear surface that is mounted on the inner peripheral surfaces of the block-side bearing portion and the journal cap. A crankshaft bearing including a bearing metal, wherein the journal cap is provided with tilting means for tilting the crankshaft bearing in the same direction as the tilting direction of the crankshaft caused by belt tension during engine warming. Crankshaft bearings. (2) The tilting means is made of a material having the same or substantially the same thermal expansion coefficient as that of the cylinder head, one end of the tilting means is attached to the lower end of the journal cap, and the other end of the tilting means is attached. The crankshaft bearing according to (1), which is attached to an engine part other than the journal cap to which one end of the tilting means is attached.

[0005]

In the crankshaft bearing of the above (1), the tilting means tilts the crankshaft bearing in the same direction as the tilt of the crankshaft when the engine is warm, so that the tilt of the crankshaft with respect to the bearing metal is reduced, increasing the friction and the clearance. The increase is also reduced. Also, since the bearing metal is the back of the cylindrical surface,
The bearing metal does not slide between the block side bearing portion and the journal cap, and there is no risk of fretting. The crankshaft bearing of (2) above has the following actions in addition to the actions of the crankshaft bearing of (1) above. That is, since the tilting means is made of the same or substantially the same thermal expansion material as the cylinder head, the tilting means is almost synchronized with the inclination of the crankshaft during warm time and in proportion to the amount of inclination of the crankshaft. By tilting the crankshaft journal bearing, suppression of increase in friction and suppression of increase in clearance are effectively achieved.

[0006]

1 to 3 are a first embodiment of the present invention, FIG. 4 is a second embodiment of the present invention, and FIG. 5 is a third embodiment of the present invention.
FIG. 6 shows a fourth embodiment of the present invention. Components common to all the embodiments are given the same reference numerals in all the embodiments.

First, constituent parts common to all the embodiments of the present invention will be described with reference to, for example, FIGS. 1 to 3, a crankshaft bearing 10 according to an embodiment of the present invention includes a block side bearing portion 13 formed in a cylinder block 12 of an internal combustion engine 11, and a journal cap 14 bolted to the block side bearing portion 13. , Block side bearing 1
3 and a bearing metal 15 having a cylindrical rear surface, which is mounted on the inner peripheral surface of the journal cap 14. The crankshaft 16 is rotatably supported by the crankshaft bearing 10. Timing belt tension A and V-ribbed belt tension B are applied to the tip of the crankshaft 16. The timing belt transmits the crankshaft rotation to the camshaft (not shown), and the V-ribbed belt transmits the crankshaft rotation to the alternator and accessories. A cylinder head (not shown) is mounted on the cylinder block 12. The cylinder block 12 is made of cast iron, but the cylinder head is made of aluminum alloy.

During engine warming (after engine warming up), the thermal expansion of the cylinder head is large, so belt tension increases compared to when engine cold (before engine warming up), and the crankshaft 16
, The tip on the side where the belt tension is applied is lifted and tilted. The crankshaft bearing 10 includes # 1, # from the tip of the crankshaft 16 on the side where the tension is applied to the crankshaft 16 toward the opposite side.
We will call them with numbers 2, ... When the tip of the crankshaft 16 is lifted by the belt tension, the # 1 crankshaft bearing 10 has the following points from the tension and the point of application of tension.
The # 1 crankshaft bearing 10 tries to incline in the same direction as the inclination direction of the tip portion of the crankshaft 16 due to the moment of the product of the distance to the one crankshaft bearing.

The crankshaft bearing 10 whose inclination is desired to be suppressed, particularly the # 1 crankshaft bearing 10, has a journal cap 14 in the same direction as the inclination direction of the crankshaft 16 caused by belt tension when the engine is warm. 10
A tilting means 17 (crankshaft bearing tilting means) for tilting is attached. The tilting means 17 is made of a material having the same or substantially the same coefficient of thermal expansion as that of the cylinder head, for example, an aluminum alloy. Further, one end of the tilting means 17 has a crankshaft bearing 10 whose tilt is desired to be suppressed.
It is attached to the lower end of the journal cap 14 (# 1 crankshaft bearing in the illustrated example), and the other end of the inclining means 17 is attached to an engine part other than the journal cap 14 to which one end of the inclining means 17 is attached. ing.

Next, the structure peculiar to each embodiment of the present invention will be described. In the first embodiment of the present invention, as shown in FIGS. 1 to 3, the tilting means 17 is made of an aluminum alloy,
One end of the tilting means 17 is fastened to the lower end of the journal cap 14 of the # 1 crankshaft bearing 10 with a bolt 18, and the other end of the tilting means 17 is fastened to the side wall of the cylinder block 12 with a bolt 19. The tilting means 17 extends linearly from the end on the side of attachment to the journal cap 14 horizontally and diagonally to the longitudinal axis of the cylinder block to the end on the side of attachment to the cylinder block 12. As shown in FIG. 2 when viewed from the bottom, the tilting means 17 has a V-shape, and the two sides of the H-shape are integrated at the apex of the H-shape.

In the second embodiment of the present invention, as shown in FIG. 4, the tilting means 17 has a bearing beam shape, and the entire bearing beam shape is made of an aluminum alloy. Therefore, one end of the tilting means 17 is fastened to the lower end of the journal cap 14 of the # 1 crankshaft bearing 10 by the bolt 18, and the other end of the tilting means is the other (# 2, # 2).
It is fastened to the lower end of the journal cap 14 of the crankshaft bearing 10 (3, # 4, # 5) by bolts 18.

Although the tilting means 17 of the third embodiment of the present invention has a structure similar to that of the second embodiment of the present invention, the difference from the second embodiment is that the third embodiment of the present invention is different. Then, as shown in FIG. 5, on the mounting surfaces 20 and 21 of the tilting means 17 to the journal cap 14 of the # 1 and # 2 crankshaft bearings, between the # 1 and # 2 crankshaft bearings of the tilting means 17. When the portion 22 at the position of the cylinder block 12 extends relatively to the cylinder block 12,
1 is # 1, # 2 crankshaft bearing journal cap 1
4 is provided with a step in the direction of engagement without slipping. The steps of the mounting surfaces 20 and 21 are in opposite directions to each other.

The tilting means 17 of the fourth embodiment of the present invention has a structure similar to the tilting means of the second embodiment of the present invention, but the difference from the second embodiment is that the fourth embodiment of the present invention. Then, as shown in FIG. 6, the tilting means 17 has a bearing beam shape, and among the bearing beam shape portions,
Only the portion 23 on the # 1 crankshaft bearing side of the portion between the # 1 crankshaft bearing and the # 2 crankshaft bearing is made of aluminum alloy, and the other portion is the cylinder block 1.
It is made of a material (for example, cast iron) having the same or substantially the same thermal expansion coefficient as that of No. 2.

Next, the operation will be described. First, the operation common to all the embodiments of the present invention will be described. The inclining means 17 does not incline the crankshaft bearing 10 when the engine is cold, but when the engine is warm when the tip of the crankshaft 16 is inclined by the belt tension, the # 1 crankshaft bearing 1 is in the same direction as the inclination of the crankshaft.
0 (particularly the journal cap 14) is pushed forward (the side where the belt tension is applied) and tilted (from the solid line in FIG. 3 to the two-dot chain line state). Since the back surface of the bearing metal 15 is a cylindrical surface, the bearing metal 15 tilts integrally with the tilt of the journal cap 14. As a result, in the # 1 crankshaft bearing 10,
The pressure contact force between the crankshaft 16 and the upper part of the front part of the bearing metal 15 is reduced to reduce the bearing frictional force and wear, and the clearance between the crankshaft 16 and the lower part of the front part of the bearing metal 15 is also reduced, resulting in a tapping sound ( The striking sound generated by the contact between the crankshaft and the lower part of the bearing metal 15 during the explosion process is reduced. When the crankshaft bearing 10 is warm, the journal cap 14 and the bearing metal 15 are integrally tilted, so that there is no sliding between the back surface of the bearing metal 15 and the journal cap 14, and no fretting occurs. . Further, since the crankshaft bearing 10 does not tilt during cold, there is no increase in friction during cold such as when tilted from cold.

Next, the operation peculiar to each embodiment of the present invention will be described. In the first embodiment of the present invention, one end of the tilting means 17 has the journal cap 14 of the # 1 crankshaft bearing 10.
Since the other end is attached to the cylinder block 12, the # 1 crankshaft bearing 10 is pushed forward with respect to the cylinder block 12 and leans when the engine is warm. Since the cylinder block 12 can sufficiently receive the reaction force from the tilting means 17, the tilting means 17 has a # 1 crankshaft bearing 10.
Can be tilted enough. Further, since the coefficient of thermal expansion of the material of the inclining means 17 is the same as or substantially the same as that of the cylinder head, the inclining means 17 corresponds to the # 1 crankshaft in response to the belt tension which increases corresponding to the thermal expansion of the cylinder head. By tilting the bearing 10, the increase in friction and the increase in clearance in the # 1 crankshaft bearing 10 are effectively suppressed.

In the first embodiment described above, the engine vibration is transmitted directly to the cylinder block skirt through the tilting means 17, so that the cylinder block radiated noise may become large. However, in the second embodiment of the present invention, since the tilting means 17 has the bearing beam structure, the engine vibration is not directly transmitted to the cylinder block 12, and therefore the cylinder block radiated sound is not increased. In the second embodiment, the entire bearing beam-shaped tilting means 17 is made of a material having a coefficient of thermal expansion equivalent to that of the cylinder head, such as aluminum alloy, so that the # 1 crankshaft bearing 10 is pushed forward and tilted. In the third embodiment of the present invention, since the mounting surface of the tilting means 17 to the journal cap 14 is provided with a step, the pushing force of the tilting means 17 is reliably transmitted to the journal cap 14 and the tilting means 17 The journal cap 14 does not slip on the mounting surface.
In the fourth embodiment of the present invention, only the vicinity of the # 1 crankshaft bearing of the bearing beam-shaped tilting means 17 is made of aluminum alloy and the parts after the # 2 crankshaft bearing are made of iron. Only 10 can be tilted, and the bearing friction after the # 2 crankshaft bearing can be kept low.

[0017]

According to the crankshaft bearing of the first aspect of the present invention, since the tilting means is provided, the crankshaft bearing can be tilted in accordance with the crankshaft tilt when the engine is warm, which increases the bearing friction and the bearing clearance. The increase can be suppressed.
According to the crankshaft bearing of the second aspect, the tilting means is made of a material having a thermal expansion coefficient that is the same as or substantially the same as the thermal expansion coefficient of the cylinder head. Therefore, the crankshaft bearing is tilted in accordance with the inclination of the crankshaft. You can

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of an internal combustion engine equipped with a crankshaft bearing according to a first embodiment of the present invention.

FIG. 2 is a bottom view of the crankshaft bearing of the internal combustion engine of FIG. 1 and its vicinity.

3 is a tilt displacement diagram of the journal cap of the crankshaft bearing of FIG. 1. FIG.

FIG. 4 is a partial cross-sectional view of an internal combustion engine equipped with a crankshaft bearing according to a second embodiment of the present invention.

FIG. 5 is a partial sectional view of a crankshaft bearing according to a third embodiment of the present invention.

FIG. 6 is a partial sectional view of a crankshaft bearing according to a fourth embodiment of the present invention.

[Explanation of symbols]

 10 Crankshaft Bearing 12 Cylinder Block 13 Block Side Bearing 14 Journal Cap 15 Bearing Metal 16 Crankshaft 17 Tilt Means

Claims (2)

[Claims] 1. A block-side bearing portion formed on a cylinder block, a journal cap bolted to the block-side bearing portion, and a cylindrical surface mounted on the inner peripheral surfaces of the block-side bearing portion and the journal cap. In a crankshaft bearing having a rear bearing metal, a tilting means for tilting the crankshaft bearing in the same direction as the direction of the crankshaft tilt caused by belt tension during engine warming is attached to the journal cap. Characteristic crankshaft bearing. 2. The tilting means is made of a material having the same or substantially the same coefficient of thermal expansion as the coefficient of thermal expansion of the cylinder head, and one end of the tilting means is attached to the lower end of the journal cap. The crankshaft bearing according to claim 1, wherein the end is attached to an engine part other than the journal cap to which one end of the tilting means is attached.