JP3241265B2 - Connecting rod bearing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a connecting rod large end bearing structure for a reciprocating internal combustion engine.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a conventional connecting rod. In the drawing, reference numeral 1 denotes a connecting rod main body, and a large end bearing 4 and a small end bearing 5 are connected to a crank pin 2 and a piston pin 3, respectively, and apply an explosion pressure applied to the piston to a piston pin 3 via a rod 6. To the crank pin 2. The large end bearing 4 has a split structure of a connecting rod body 1 and a cap 7.
A semicircular back metal 8 is mounted on the inner surfaces of the main body and the cap, respectively.
1, the cap bolt 9 is firmly fastened. A bearing bush 10 is press-fitted into the small end bearing 5.

[0003]

However, particularly during operation of the four-cycle internal combustion engine, the inertia force of the reciprocating portion causes the large end to have a periodic reaction force by the crank pin in the direction of the cap, that is, the reaction force at the cap side. A load acts on the lower half of a bearing.

This load causes the large end bearing, which is a sliding bearing in the cap 7, to be elastically deformed in a tensile direction in the vertical direction. This is generally called close-in, and an oil film is formed on the large end bearing. Making it difficult.

Particularly, in recent high-speed, high-power engines, an excessive inertia force is applied, so that a large end is largely elastically deformed, and there is a concern that a bearing may be burned out by close-in.

An object of the present invention is to provide a connecting rod bearing in which the occurrence of close-in is suppressed as compared with a conventional connecting rod bearing, seizure resistance of the bearing is improved, and sound operation is possible.

[0007]

SUMMARY OF THE INVENTION A connecting rod bearing according to the present invention comprises a connecting rod connecting a piston of a reciprocating internal combustion engine and a crankpin. By providing a partial slit along the circumferential direction to reduce the rigidity in the radial direction of the bearing, elastic deformation of the bearing can be easily obtained even at a lower level of oil film pressure than before, which is advantageous for oil film formation and works in close-in The characteristic feature is that the adverse effects due to are reduced.

[0008]

In the above invention, by reducing the rigidity of the cap-side bearing in the radial direction near the bearing alignment, the bearing can be easily elastically deformed even at a somewhat low level of oil film pressure, which is advantageous for forming an oil film. Work close-in is reduced.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Generally, a plain bearing is designed to float and support a shaft by an oil film pressure generated in a lubricating oil existing between the shaft and the bearing. The bearing itself undergoes elastic deformation by the oil film pressure. . The moderate elastic deformation of the bearing not only increases the range of oil film pressure generation but also greatly contributes to the formation of an oil film by making the oil film thickness uniform, and generally brings about a favorable result in terms of lubrication performance.

In a forced hydraulic lubricating reciprocating internal combustion engine, lubricating oil usually flows from a crank journal to a crankpin through an oil hole in a crankshaft, and then through a vertical groove of a main body-side bearing at a large end of a connecting rod. but in which the lubricating oil flows on the side of the bearing, when the cap side load
As shown in FIG. 6, the oil film pressure distribution on the bearing surface tends to decrease as the oil film pressure distribution approaches the bearing mating surface.

[0011] Moreover in particular operated four-cycle reciprocating engine at a high speed top dead center of the exhaust stroke, since the large kina force that attributable to the reciprocating inertia force on the cap side bearing surface is applied, FIG. 5 When the phenomenon of close-in occurs as shown in (1), it becomes difficult to deform the bearing surface outward due to the hydraulic pressure drawn inward. Therefore, as shown in FIGS. 1 to 3, partial slits 13a and 13b are provided partially in the circumferential direction on the cap side from the mating surface of the large end to reduce the rigidity in the bearing radial direction, so that elastic deformation can be easily obtained at that location. The structure is such that the area of the lubricating oil intake is widened.

A connecting rod bearing according to an embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a configuration diagram of a connecting rod, FIG. 2 is a front view of a cap and a plan view of a mating surface, and FIG. 3 is an operation explanatory diagram of the present invention.

In FIG. 1, reference numeral 13 denotes a partial slit,
A slit-shaped space extending in the direction of the crankpin from the cap mating surface 11 along the bearing circumferential direction is formed in a part thereof. Further, as shown in the cap mating surface of FIG. 2, the partial slit 13 is uniformly cut in the axial direction. As a result, in the circumferential direction where the partial slits 3 are provided, the rigidity in the radial direction of the bearing is lower than in the conventional example having no partial slits.

Therefore, even when the lubricating oil pressure is relatively low compared to the comparative product, the bearing surface on the partial slit 13 can easily undergo elastic deformation in the bearing radial direction as shown in FIG. Reduces the decrease in lubrication performance due to close-in and works favorably in forming an oil film.

[0015]

In the connecting rod large end bearing according to the present invention, a partial slit for reducing rigidity in the bearing radial direction, which is a component, is provided in the cap portion thereof.
When a load is applied from the crankpin in the cap direction, the degree of close-in that makes it difficult to form an oil film can be reduced even when the bearing itself elastically deforms from the cap bolt. In addition, as compared with the conventional connecting rod bearing, adverse effects due to the occurrence of close-in are suppressed, the seizure resistance of the bearing is improved, and the bearing strength is significantly improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a connecting rod according to an embodiment of the present invention.

FIG. 2 is a front view of a cap and a plan view of a mating surface according to the embodiment of the present invention.

FIG. 3 is a schematic diagram illustrating an effect of the connecting rod large end bearing according to the embodiment of the present invention.

FIG. 4 is a configuration diagram of a conventional connecting rod.

FIG. 5 is a schematic diagram illustrating the occurrence of close-in in a conventional connecting rod large end bearing.

FIG. 6 is a schematic diagram showing a circumferential oil film pressure when the close-in shown in FIG. 5 occurs.

[Explanation of symbols]

1 ... connecting rod body, 2 ... crank pin, 3
... Piston pin, 4 ... Large end bearing, 5 ... Small end bearing, 6
... rod part, 7 ... cap, 8 ... back metal, 9 ... cap fastening bolt, 10 ... bearing push, 11 ... large end bearing mating surface, 12 ... cap fastening bolt hole, 13 ... partial slit.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16C 9/04-9/06 F02B 75/32 F01M 1/06

Claims (1)

(57) [Claims] At a large end portion of a connecting rod connecting a piston pin and a crank pin of a reciprocating internal combustion engine,
A partial slit is provided along the circumferential direction in the axial direction of the crank pin only on the cap side from the mating surface of the large end bearing to reduce the rigidity of the bearing in the radial direction. A connecting rod bearing, which is easily deformed, has an advantageous effect on oil film formation, and suppresses the adverse effect of close-in.