JP2001124050A - Main bearing for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sliding bearing for engine capable of preventing the part receiving a radial load originating from the tension of a cogged belt or a V-belt from abnormal wear or a seizure. SOLUTION: The main portion of a crank shaft receives a load from the tension of a cogged belt or a V-belt and makes single-sided contacting with the upper half split bearing 13 of a main bearing. In this single-sided contacting part, balls 28 are installed rotatably, and the main shaft portion 2 is borne by the balls 28. Accordingly the single-sided contacting part is free of risk to make abnormal wear or a seizure even if the main shaft portion 2 begins rotating in the condition with less quantity of lubricating oil when the engine is being started.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a main bearing for an engine, which supports a crankshaft to which a radial load always acts in one direction due to the tension of a belt applied for transmitting rotation, and more particularly to the one-way main bearing. It relates to a structure in which a radial load is received by a rolling element.

[0002]

2. Description of the Related Art For example, in a gasoline engine for an automobile, rotation of a crankshaft is used to drive a camshaft, an alternator, a compressor for an air conditioner, and the like. For transmitting the rotation, the crankshaft is connected to the camshaft via a toothed belt, and is connected to the alternator and the compressor via a V-belt.

[0003] These toothed belts and V-belts are given a predetermined tension in order to prevent slippage or the like. A radial load acts on the crankshaft due to the tension applied to the toothed belt and the V-belt, and the radial load is applied by a slide bearing (hereinafter, referred to as a main bearing) that supports a main shaft portion of the crankshaft. Can be received.

The direction of the resultant force of the radial load acting on the crankshaft due to the tension of the toothed belt or the V-belt is as follows:
The direction is determined so as to be opposite to the direction of the combustion pressure received via the piston during rotation of the engine. The reason is that in recent engines, there are many overhead camshaft types, and since the camshaft is provided above the cylinder block, the tension of the toothed belt becomes upward. For example, in the case of an in-line four-cylinder engine, the crankshaft is rotating. Receives the downward combustion pressure from the piston, and
This is because the radial load acting on the crankshaft due to the belt tension is directed upward to reduce the surface pressure of the main bearing.

[0005]

The radial load due to the tension of the toothed belt or V-belt always acts on the crankshaft regardless of whether the engine is rotating or stopped, and the main shaft portion of the crankshaft is The radial load constantly presses the main bearing. While the engine is running, lubricating oil is supplied to the main bearings from the oil pump. However, when the engine stops, the lubricating oil supply to the main bearings also stops. Metal contact occurs in which the main shaft portion of the shaft directly contacts the main bearing.

When the engine is restarted, the oil pump is also started, but the supply of lubricating oil from the oil pump is delayed in time. For this reason, the main shaft portion of the crankshaft rotates in an incompletely lubricated state, which may cause early wear or seizure.

In particular, recently, a so-called hybrid car using an engine and an electric motor in combination, and an engine is stopped when stopping at an intersection in order to minimize the emission of combustion gas that causes global warming. Such engines are commercially available, and such engines are frequently started and stopped, and are controlled so as to rotate at high speed beyond the idling rotation range immediately after starting. Will be more and more in the future,
Immediate measures are needed.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an engine main bearing which can prevent abnormal wear and seizure of a slide bearing surface.

[0009]

According to the first aspect of the present invention, a rolling element is provided at a portion where a crankshaft is pressed by a radial load in one direction. When the shaft starts to rotate, the rolling element rotates while receiving a radial load in one direction. As described above, in the one-side contact portion of the crankshaft due to the radial load, the presence of the rolling element does not cause the crankshaft to directly contact the sliding bearing surface but comes into contact with the sliding bearing element via the rotatable rolling element. There is no danger of burning or burning. In this case, the rolling element can be a ball or a needle as described in claim 2.

According to the third aspect of the present invention, the rolling bearing portion is a portion where the crankshaft is pressed by the radial load in one direction. Therefore, when the engine is started and the crankshaft starts rotating, the rolling element of the rolling bearing portion is changed. It rotates while receiving a radial load in one direction. For this reason, there is no fear that the bearing surface of the sliding bearing portion is abnormally worn or seized.

In this case, it is preferable that the rolling bearing is eccentric relative to the sliding bearing in a direction opposite to a direction in which the radial load acts. In this case, the combustion pressure acts on the crankshaft during the rotation of the engine, but the combustion pressure does not press the crankshaft against the rolling bearing, so that the rolling bearing hardly rotates and the rolling bearing does not rotate. Noise generation can be prevented as much as possible.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is applied to an automobile engine will be described below with reference to FIGS. As shown in FIG. 4, the crankshaft 1 of the automobile engine includes a main shaft portion 2, a crankpin 3, and a crank arm 4. Crankshaft 1 of this embodiment
Indicates an in-line four-cylinder engine, and has a structure in which a main shaft portion 2 and a crankpin 3 are alternately arranged.

The crankshaft 1 is arranged below the cylinder block 5. As shown in FIG. 3, a bearing cap 6 is fixed to the lower portion of the cylinder block 5 by bolting, and the cylinder block 5 and the bearing cap 6 constitute a bearing housing 7. And
The main shaft 2 of the crankshaft 1 is supported by slide bearings (hereinafter, main bearings) 8 to 12 attached to the bearing housing 7. The main bearings 8 to 1 supporting the main shaft 2
2 is the first,
Numbers are assigned, such as second.

As shown in FIG. 3, the main bearings 8 to 12 are split-type bearings (hereinafter referred to as "half-split bearings").
3 and 14, one of the upper half bearings 1
3 is attached to the cylinder block 5, and the other lower half bearing 14 is attached to the bearing cap 6. The two half bearings 13 and 14 are formed as cylindrical main bearings 8 to 12 by bolting the bearing cap 6 to the cylinder block 5.

The upper half bearing 13 of the main bearings 8 to 12
, An oil groove 15 is formed at the center in the axial direction and over the entire circumferential direction. Also, the upper half bearing 13
Is formed with an oil hole 16 for opening the oil groove 15 to the outside. On the other hand, partial grooves 17 are formed at both ends in the circumferential direction of the lower half bearing 14 at the center in the axial direction. When the upper and lower half bearings 13 and 14 are combined, the partial groove 17 is continuous with both ends of the oil groove 15 of the upper half bearing 13. During the rotation of the engine, the lubricating oil flows from the oil passage 18 formed in the cylinder block 5 through the oil hole 1.
6, the oil flows into the oil groove 15 and the partial groove 17 and is supplied to the slide bearing surface.

As shown in FIGS. 4 and 5, a toothed pulley 19, a V-belt pulley 20, and the like are attached to the front end of the crankshaft 1. On the other hand, a camshaft 21 for opening and closing an air supply valve and an exhaust valve is attached to an upper portion of the cylinder block 5, and a toothed pulley 22 is attached to the camshaft 21. A dynamo and a compressor for an air conditioner (only the rotating shaft 23 of one of them is shown) are attached to the side of the cylinder block 5, and a V-belt pulley 24 is attached to the rotating shaft 23.

The toothed pulley 19 of the crankshaft 1
And a V-belt pulley 22 of the camshaft 21, a V-belt pulley 20 of the crankshaft 1, and a V-belt pulley 24 of a rotating shaft 23 of a dynamo and air conditioner compressor, respectively. ing. A predetermined tension is applied to each of the toothed belt 25 and the V-belt 26 so as to prevent tooth skipping, slippage, and the like.

The crankshaft 1 receives a radial load due to the tension applied to the toothed belt 25 and the V-belt 26. In this case, the direction of the resultant radial load (hereinafter referred to as composite radial load) applied to the crankshaft 1 by the tension of the belts 25 and 26 depends on the combustion pressure that the crankshaft 1 receives via a piston (not shown) during rotation of the engine. Upward, which is the direction opposite to the direction of action of, for example, FIG.
And each belt 2 in the direction indicated by arrow A in FIG.
Tension directions of 1, 22 are defined.

The front end portion of the crankshaft 1 receives a bending moment from the tension applied to the toothed belt 25 and the V-belt 26, and the bending moment is
Is received as a radial load in the direction of arrow A by the first main bearing 8 closest to the front end of the first main bearing 8. The radial load due to this bending moment is the upper half bearing 1 of the first main bearing 8.
3, the front end portion of the crankshaft 1 bends and deforms as shown in FIG. 2, so that the front end portion of the crankshaft 1 collides with the front end side of the crankshaft 1 from the center in the width direction (axial direction) of the upper half bearing 13; Therefore, the radial load is received at the one-side contact portion. In FIG. 2, the bending of the crankshaft 1 is exaggerated.

A portion of the sliding bearing surface (inner peripheral surface) of the upper half bearing 13 of the first main bearing 8 where the crankshaft 1 hits one side due to the radial load in the direction of the arrow A (hereinafter, referred to as a "part"). As shown in FIGS. 1 and 2, a plurality of spherical concave portions 27 are formed in a single contact portion of the crankshaft 1, and a ball 28 as a rolling element is rotatably fitted in the spherical concave portion 27. ing.

Next, the operation of the above configuration will be described. The following description is for the first main bearing 8. During the rotation of the engine, the lubricating oil flows from the oil passage to the oil groove 15 of the main bearing 8,
The lubrication is supplied to the partial groove 17 to perform lubrication between the main shaft portion 2 of the crankshaft 1 and the main bearing 8. When the engine stops, the lubricating oil between the main shaft portion 2 and the main bearing 8 escapes to the outside and returns to an oil pan (not shown).
7 remains. When the engine is stopped, as shown in FIG.
The main bearing 8 is pressed against the ball 28 of the upper half bearing 13 by such tension.

When the engine is restarted in this state, the crankshaft 1 starts rotating, and the ball 28 rotates in the recess 27 with the rotation. At this time, the ball 28 is
7 is rotated by being lubricated by the lubricating oil retained in the inner surface of the recess 27, the inner surface of the recess 27 and the ball 28 are abnormally worn,
There is no risk of burning. Then, within a short time after the start of the engine, the main shaft portion 2 of the crankshaft 1 is pushed downward by receiving the combustion pressure, and is received by the sliding bearing surface of the lower half bearing 14.

FIGS. 6 and 7 show a second embodiment of the present invention. The difference between this embodiment and the first embodiment is that the first main bearing 8 has a cylindrical surface extending in the axial direction at a portion of the sliding surface of the upper half bearing 13 on one side of the crankshaft 1. A plurality of recesses 29 are formed in a line in the circumferential direction,
A so-called needle 30 in the shape of a round bar is fitted in the recess 29 as a rolling element.

FIGS. 8 and 9 show a third embodiment of the present invention. This embodiment is characterized in that the first main bearing 8 is composed of a sliding bearing portion 31 and a needle bearing portion 32 as a rolling bearing portion adjacent to the sliding bearing portion 31.

The needle bearing 32 is provided with a sliding bearing 31.
One end of the back metal 33 is formed as an outer race, and a needle 34 as a rolling element held by a retainer (not shown) is disposed inside the outer race 32a, and an inner race 35 is further formed inside the needle 34. It is arranged. In addition, the sliding bearing portion 31 and the needle bearing portion 3
2 may be divided into upper and lower portions, or may be a cylindrical shape from the beginning.

The needle bearing 32 is provided with a sliding bearing 31.
The radial load acting on the crankshaft 1 from the toothed belt 25 or V-belt 26 (direction of arrow A)
It is eccentric in the opposite direction. This eccentricity can be obtained, for example, by forming the outer race portion 33a eccentrically with respect to the slide bearing portion 31.

In the above configuration, when the engine is stopped,
As shown by a two-dot chain line in FIG.
Is the needle bearing 3 due to the radial load in the direction of arrow A.
2 is pressed against the inner race 35, and the radial load is received by the needle. In FIG. 8, the deflection of the crankshaft 1 is exaggerated.

When the engine is started, the main shaft 2 of the crankshaft 1 starts rotating while being pressed against the inner race 35. The inner race 35 rotates with the rotation of the main shaft portion 2, whereby the needle 34 revolves along the inner peripheral surface of the outer race 33a while rotating. Then, since the crankshaft 1 is pushed down by the combustion pressure within a short time after the engine starts, the main shaft portion 2 separates from the upper portion of the inner race 35 as shown by a broken line in FIG.

Here, the toothed belt 25 and the V-belt 26
The direction of the radial load acting on the crankshaft 1 due to such tension is determined in a direction substantially opposite to the direction in which the combustion pressure acts, and the needle bearing 31 is biased in a direction (downward) opposite to the direction of the arrow A. As a result, the main shaft 2 is not pressed against the lower portion of the inner race 35 even if the main shaft 2 is pressed down by the combustion pressure as described above.

During the rotation of the engine, the main shaft 2 rotates with a slight clearance between itself and the inner race 35, and the combustion pressure acting on the crankshaft 1 during the rotation of the engine is reduced by the sliding bearing. It can be received by the unit 31. Therefore, during the rotation of the engine, there is no possibility that the inner race 35 will rotate and rotate together with the main shaft portion 2, and since the combustion pressure during rotation is received by the slide bearing portion 31, the dynamic load (combustion pressure) ) Can receive an ideal bearing configuration in which the needle bearing 32 receives the static load when the engine is stopped and the load when the amount of lubricating oil is insufficient for the sliding bearing 31 immediately after the engine is started. it can.

The present invention is not limited to the embodiment described above and shown in the drawings, but can be extended or modified as follows.

The rolling element is not limited to the ball 28 or the needle 30.

The outer race of the needle bearing 32 may be separate from the backing 33 of the sliding bearing 31.

The rolling bearing is not limited to the needle bearing 32, but may be a ball bearing having a rolling element as a ball.

The rolling elements of the rolling bearing are not limited to needles and balls.

[Brief description of the drawings]

FIG. 1 is a plan view of an upper half bearing showing a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a form in which a front end portion of a crankshaft is supported by a main bearing.

FIG. 3 is a longitudinal sectional view of a main bearing portion.

FIG. 4 is a sectional view showing a crankshaft together with a main bearing.

FIG. 5 is a perspective view showing a belt transmission mechanism attached to a front end portion of the crankshaft.

FIG. 6 is a view corresponding to FIG. 1, showing a second embodiment of the present invention.

FIG. 7 is a diagram corresponding to FIG. 2;

FIG. 8 is a view corresponding to FIG. 2, showing a third embodiment of the present invention.

FIG. 9 is a front view of a main bearing.

[Explanation of symbols]

In the figure, 1 is a crankshaft, 2 is a main shaft portion, 8 is a main bearing, 1
3, 14 are half bearings, 27 is a concave portion, 28 is a ball (rolling element), 29 is a concave portion, 30 is a needle (rolling element), 31 is a sliding bearing portion, 32 is a needle bearing portion (rolling bearing portion), 33 Is back metal, 34 is needle, 3
5 is an inner race.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takayuki Shibayama 2 Sanage-cho, Kita-ku, Nagoya F-term in Daido Metal Industry Co., Ltd. (reference) 3J033 AA05 GA04 GA05 GA05 GA08 GA20

Claims (4)

[Claims] An engine main bearing for supporting a crankshaft to which a radial load always acts in one direction due to the tension of a belt applied for transmitting rotation, etc., comprising a sliding bearing, and an inner peripheral surface of the sliding bearing. Of which
A main bearing for an engine, wherein a rolling element is provided at a portion where the crankshaft is pressed by the radial load in one direction. 2. A main bearing for an engine according to claim 1, wherein said rolling element is a ball or a needle. 3. A main bearing for an engine, which supports a crankshaft to which a radial load always acts in one direction due to the tension of a belt applied for rotation transmission and the like, a sliding bearing portion, and a portion adjacent to the sliding bearing portion. And a rolling bearing for receiving the crankshaft pressed by the radial load in one direction. 4. The main bearing for an engine according to claim 3, wherein the rolling bearing is eccentric with respect to the sliding bearing in a direction opposite to a direction in which the radial load acts.