JPH11201166A - Bearing bush for piston pin for connecting rod - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve lubricity at the starting of an engine. SOLUTION: A number of indents 6 are formed on the light load side being the opposite side to the high load side, on which an expansion pressure of fuel working on a piston is exerted, of the inner peripheral surface of a bearing bush 5. Lubricating oil gathers at the indents 6. At the starting of an engine, lubrication oil gathering in the indents 6 is supplied between slide surfaces between a bearing bush 5 and a piston pin, whereby a problem on defective lubrication during the starting of an engine is dissolved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing bush for a piston pin provided on a small end side of a connecting rod of an engine, and more particularly to an improved bushing for starting an engine.

[0002]

In an engine, for example, a diesel engine, a bush is often used as a bearing for a piston pin of a connecting rod, and the bearing bush is usually provided with a small end portion of the connecting rod. Then, the bearing surface (inner peripheral surface) is finished to predetermined inner diameter dimensions and surface roughness by turning or the like before use.

Meanwhile, for a bearing attached to the large end of the connecting rod, a forced lubrication system in which lubricating oil is supplied from a lubrication pump through an oil passage formed in a cylinder block, a main bearing, and a crankshaft is adopted. ing. On the other hand, for lubricating the bearing bush at the small end, a nozzle system that jets oil from a nozzle provided in a part of the oil passage is used, and the oil from the connecting rod is supplied from the bearing at the large end. There is a type employing a forced lubrication system in which lubricating oil is supplied from a lubrication pump through a passage, or a type employing both a nozzle type and a forced lubrication system.

However, in the nozzle type, it takes time for the lubricating oil splashed on the small end of the connecting rod to enter the bearing surface of the bearing bush after the engine is started. Further, in the forced lubrication system, the bearing bush at the small end is located at the end of the oil passage from the lubricating oil pump, so that there is almost no supply of lubricating oil when the engine is started. As described above, no matter which of the nozzle system and the forced lubrication system is adopted, the bearing bush at the small end portion has a problem that the lubrication is inferior due to insufficient lubrication when the engine is started.

As a solution to this, conventionally, an oil groove has been formed on the bearing surface of the bearing bush. However, considering that recent diesel engines tend to increase the combustion pressure from the viewpoint of increasing the output or taking measures against exhaust gas, the provision of an oil groove reduces the pressure receiving area. Can not respond to.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a bearing bush for a connecting rod piston pin which can improve lubricity at the time of starting the engine.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a bearing bush for a pin-ton pin of a connecting rod which is fitted to a small end of a connecting rod of an engine and supports a piston pin. The indent is formed on the light load side of the surface. In this case, a solid lubricant can be embedded in the indent.

According to the above means, when the engine is stopped, the indent contains lubricating oil supplied between the sliding surfaces of the bearing bush and the piston pin during the previous operation of the engine, or a solid lubricant. Exists. Therefore, when the engine is restarted, the lubricating oil or solid lubricant in the indent is supplied between the sliding surfaces of the bearing bush and the pinton pin. Also, since the indent is provided on the light load side and such an indent is not provided on the high load side which receives the explosion pressure of the fuel acting on the piston, it is necessary to reduce the pressure receiving area on the high load side. No failure occurs.

In the present invention, in order to facilitate the processing of the indent, the shape of the indent can be made circular on the bearing surface. Also, in order to increase the area ratio of indent,
The shape can be rhombic on the bearing surface.
Further, in the present invention, the bearing surface of the bearing bush can be formed of a Cu-based or Al-based bearing alloy and a Pb-free bearing alloy (a degree of impurities is allowable). In bearing bushings for piston pins, Cu-based alloys such as Cu-10% Sn-10% Pb have been generally used as bearing alloys. However, Pb in the Cu-based alloy does not bear much load and is easily corroded by the degraded oil, and if corroded, the load capacity of the bearing alloy is significantly reduced. And in modern engines, especially diesel engines,
The combustion pressure tends to increase and the bearing surface pressure tends to increase, and some of them reach 100 to 120 MPa. Along with this, it is necessary to increase the fatigue resistance and wear resistance of the bearing alloy. For this purpose, there is a method of eliminating Pb to secure the strength. Also, reducing the content of Pb does not adversely affect the environment, and the present invention is excellent in both strength improvement and environmental measures.

[0010]

FIG. 1 shows a first embodiment of the present invention.
This will be described with reference to FIG. FIG. 2 shows a connecting rod 1 of a diesel engine, for example. This connecting rod 1 connects a piston and a crankpin 2 of a crankshaft, and a large end mounted on the crankshaft side is provided with a two-part bearing 3 for receiving the crankpin 2 of the crankshaft. A bearing bush 5 for receiving the pin ton pin 4 is attached to a small end attached to the piston.

When the fuel injected into the cylinder on the high load side, that is, in the cylinder explodes on the surface of the bearing alloy layer which is the inner peripheral bearing surface of the bearing bush 5, it receives the explosion pressure of the fuel acting on the piston. The large end (lower side in FIG. 2) is shown in FIG.
Although it has a flat cylindrical surface as shown in (b), a large number of indents 6 are formed on the opposite light load side (upper side in FIG. 2) as shown in FIG. 1 (a). I have. The indent 6 has a spherical concave shape and a circular outer shape on the bearing surface.

The above-mentioned bearing bush 5 is of a so-called wound bush type. This winding bush type bearing bush 5
Cuts a bimetal formed by lining a bearing alloy (both not shown) made of, for example, phosphor bronze on the surface of a steel back metal into strips as shown in FIG. The indent 6 is formed by molding, for example, by press molding in a step before the rectangular bimetal is molded into a cylindrical shape. In this case, as the bearing alloy of the bearing bush 5, a Cu-based bearing alloy that does not contain Pb (containment as an impurity is allowed), for example, phosphor bronze (Cu-0.05P-5Sn) is used.

The above-mentioned bearing bush 5 formed into a cylindrical shape with the indent 6 formed therein is inserted into the housing hole 7 formed at the small end of the connecting rod 1.
Is press-fitted so that the formation surface side is located on the opposite side to the large end. At this time, when the bearing bush 5 is pressed into the housing hole 7 at a regular position, the oil hole 8 formed in the bearing bush 5 is brought into communication with the oil hole 9 formed in the small end of the connecting rod 1. Become. Thereafter, the entire circumference of the bearing surface of the bearing bush 5 is machined by turning or the like, and finished to predetermined inner diameter dimensions and surface roughness.

In the connecting rod 1 having such a bearing bush 5, during operation of the engine, the lubricating oil from the lubricating pump is supplied to the bearing 3 for the crank pin 2 through the oil passage ( (Not shown). On the other hand, when the engine is started, the lubricating oil from the lubrication pump through the oil passage of the block is splashed from the nozzle to the small end of the connecting rod 1. The lubricating oil splashed on the small end portion penetrates between the piston pin 4 and the sliding surface of the bearing bush 5 through the oil hole 9 of the small end portion and the oil hole 8 of the bearing bush 5, or It penetrates between the sliding surfaces of the piston pin 4 and the bearing bush 5 through gaps at both ends of the bush 5, and lubricates the sliding surface.

When the engine is stopped, part of the lubricating oil present on the sliding surfaces of the piston pin 4 and the bearing bush 5 escapes from the gap between the sliding surfaces and returns to the oil pan. The accumulated lubricating oil stops in the indent 6 without escaping.
Then, when the engine is restarted, the lubricating oil in the indent 6 is supplied between the piston pin 4 and the sliding surface of the bearing bush 5 to lubricate the sliding surface.

As described above, according to the present embodiment, since the indent 6 is formed in the bearing bush 5, when the engine is stopped, the lubricating oil that has been supplied to the sliding surfaces of the piston pin 4 and the bearing bush 5 until then is stopped. The state is stored in the indent 6. Therefore, when the engine is restarted, the lubricating oil in the indent 6 is supplied to the sliding surfaces of the piston pin 4 and the bearing bush 5, so that the problem of insufficient lubricating oil at the time of starting the engine is solved, and a seizure accident or the like is solved. Can be prevented from occurring.

Further, since the indent 6 is formed on a portion of the bearing surface of the bearing bush 5 opposite to the large end portion,
It is possible to effectively cope with an increase in the combustion pressure of the engine without reducing the pressure receiving area of the bearing surface on the large end portion which directly receives the combustion pressure acting on the piston. In addition, since the bearing area on the light load side can be appropriately reduced, unnecessary friction with the piston pin 4 can be reduced, and the efficiency of the engine is improved.

Further, in this embodiment, since the shape of the indent 6 is set to be circular, a press die for molding the indent 6 can be easily manufactured, and when the indent 6 is molded using the press die, molding is easy. In addition, since the indent 6 has a spherical depression, unlike the case of a square press molding, the amount of deformation of the strip-shaped bimetal is small, and it is easy to form the cylinder into a cylindrical shape.

In this embodiment, a Cu-based bearing alloy, for example, phosphor bronze is used as the bearing alloy of the bearing bush 5. This phosphor bronze does not contain Pb and has high strength. For this reason, it is possible to cope with the recent increase in the combustion pressure of the diesel engine, and it is possible to achieve excellent fatigue resistance and wear resistance. Further, by not containing Pb, there is no adverse effect on the environment.

FIGS. 4 to 7 show second to fifth embodiments of the present invention. First, the second embodiment of FIG.
Is formed in an elliptical shape or an oval shape. In the third embodiment shown in FIG. 5, the indent 11 is formed in a diamond shape. When the indent 11 has a diamond shape in this way, the indent 11 is not spherical but concave in a square shape, so that the inner volume can be increased, and the amount of lubricating oil captured by the indent 11 increases. can do. Further, if the diagonal direction of the diamond-shaped indent 11 is made to coincide with the swinging direction of the bearing bush 5, the lubricating oil supply becomes smoother.

In the fourth embodiment shown in FIG. 6, an oil groove 12 communicating with the oil hole 8 is formed on both ends of the bearing surface of the bearing bush 5, and in the fifth embodiment shown in FIG. An oil groove 13 communicating with the oil hole 8 is formed in a part of the surface where the indent 6 is formed. By forming the oil grooves 12 and 13 on the bearing surface in this manner, lubricity during operation of the engine can be better ensured.

FIG. 8 shows a sixth embodiment of the present invention.
In FIG. 8C, a resin such as Sn, Sn alloy, graphite, or polyamideimide, and a solid lubricant 14 such as molybdenum disulfide are provided in the indent 6. FIG.
An example of a processing procedure when the solid lubricant 14 is embedded in the state as shown in FIG. 8C will be described. First, as shown in FIG. 8A, an indent 6 is formed on the bearing surface of the bearing bush 5, and As shown in FIG. 8B, a solid lubricant 14 is applied to the entire bearing surface of the bearing bush 5 by electroplating, coating, or the like, and the bearing bush 5 is pressed into the housing hole 7 of the connecting rod 1. After that, the inner peripheral surface of the bearing bush 5 is turned to finish processing so that the solid lubricant 14 remains only in the indent 6. Thus, the solid lubricant 14 is embedded in the indent 6 as shown in FIG.

As described above, the solid lubricant 14 is added to the indent 6.
Is provided, the solid lubricant 14 is supplied between the sliding surfaces of the bearing bush 5 and the piston pin 4 when the engine is started, so that lubricity can be ensured. In this case, as in the present embodiment, if the layer thickness of the solid lubricant 14 is made relatively thin so that a depression occurs in the solid lubricant 14 in the indent 6, lubricating oil is stored in the depression 14a. When the engine is started, both the solid lubricant 14 and the lubricating oil cause the bearing bush 5 and the piston pin 4
Between the sliding surfaces can be lubricated. When the solid lubricant 14 is provided on the indent 6, when turning the bearing surface of the bearing bush 5, it is possible to minimize the occurrence of burrs when the cutting edge of the cutting tool moves from the bearing surface to the indent 6, It is possible to prevent the occurrence of injury accidents.

When the solid lubricant 14 is embedded in the indent 6, the indent 6 may be completely filled with the solid lubricant 14 as in the seventh embodiment of the present invention shown in FIG. Of course.

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 shape of the indent may be a triangle, a rectangle, a polygon, or various other shapes. The range in which the indent is formed is not limited to that formed on the entire half of the bearing surface on the light load side, and may be formed on a part of the light load side bearing surface. Further, it may be formed over half or more except for the main load portion. The present invention is not limited to a diesel engine, and may be applied to a pin-ton pin bearing bush of a connecting rod of a gasoline engine.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention, in which (a) is a perspective view showing one half of a bearing surface of a bearing bush, and (b) is a perspective view showing the remaining one half.

FIG. 2 is a front view of a connecting rod.

FIG. 3 is an inner view of a bearing bush.

FIG. 4 is a view corresponding to FIG. 3, showing a second embodiment of the present invention;

FIG. 5 is a view corresponding to FIG. 3, showing a third embodiment of the present invention.

FIG. 6 is a view corresponding to FIG. 3, showing a fourth embodiment of the present invention;

FIG. 7 is a view corresponding to FIG. 3, showing a fifth embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a sixth embodiment of the present invention and sequentially illustrating steps for attaching a solid lubricant to an indent.

FIG. 9 is a sectional view showing a seventh embodiment of the present invention.

[Explanation of symbols]

In the figure, 1 is a connecting rod, 2 is a crankpin,
4 is a piston pin, 5 is a bearing bush, 6, 10 and 11 are indents, and 14 is a solid lubricant.

Claims (5)

[Claims] 1. A bearing bush, which is fitted to a small end side of a connecting rod of an engine and supports a piston pin, wherein an indent is formed on a light load side of a bearing surface. Bearing bush. 2. The bearing bush for a piston rod of a connecting rod according to claim 1, wherein a solid lubricant is provided in the indent. 3. The bearing bush for a piston rod of a connecting rod according to claim 1, wherein the indent is circular in a bearing surface. 4. The bearing bush for a piston rod of a connecting rod according to claim 1, wherein the indent has a diamond shape on a bearing surface. 5. The bearing according to claim 1, wherein the bearing surface is made of a Cu-based or Al-based bearing alloy and does not contain Pb (impurity is allowable). A bearing bush for the connecting pin of the described connecting rod.