JPH0446087Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a half-split flat bearing used for the main bearing of a crankshaft of an internal combustion engine, a compressor, etc. or the big end bearing of a connecting rod.

[Conventional technology]

Conventionally, semi-cylindrical half-split flat bearings used as the main bearing of a crankshaft or the big end bearing of a connecting rod have had a wall thickness that gradually decreases from the center in the circumferential direction toward both ends. The reason is as follows. The two-part housing of the main bearing of the crankshaft, or the two-part housing consisting of the rod side and the cap side of the large end of the connecting rod, is assembled by tightening the bolts to the specified torque, then tightening the bolts into the holes in the housing. The section was machined into a substantially perfect circle, and then a pair of half-split flat bearings were installed. When an internal combustion engine, compressor, etc. is operated, the inner diameter of the bearing becomes a substantially perfect circle due to the deformation of the housing due to the tensile force _F1 in the Y-Y axis direction shown in FIG.

[The problem that the idea aims to solve]

However, in response to the reduction in weight of internal combustion engines, housing strength has been designed to the limit, excess wall thickness has been reduced as much as possible, and housings made of aluminum alloy have come to be adopted. In a half-split flat bearing used in a relatively low-rigidity housing, as shown in Figure 2, the tensile force F ₁ in the Y-Y axis direction that acts on the housing during operation causes the hole to be damaged in the X-X axis direction. Enlargement of the hole in the X-X axis direction due to the compressive force _F2 in the Y-Y axis direction based on the tightening of bolts and nuts during assembly ensures better oil lubrication than the relative reduction of the hole. It has become an important issue. This phenomenon occurs significantly when a housing divided into two parts is bolted together with a relatively large tightening force.

[Means to solve the problem]

The present invention is a half-split flat bearing that copes with the deformation of the housing due to the tightening force of bolts when a pair of half-split flat bearings are assembled into the holes of a two-split housing as the main bearing of a crankshaft or the large end bearing of a connecting rod. A plain bearing is provided, and its configuration is as follows.

A pair of half-split flat bearings which are disposed abutting against a substantially perfectly circular hole in a housing as a main bearing of a crankshaft or a large end bearing of a connecting rod,
The outer diameter of the bearing, which is arcuate before assembly, is gradually increased from the center to both ends in the circumferential direction, and the housing is divided into two parts. This is a half-split flat bearing whose wall thickness is set so that the inner diameter becomes a substantially perfect circle by compensating for the elongation of the hole in the direction connecting the mating surfaces of the housing when assembled by bolting. .

[Effect]

Therefore, this pair of half-split flat bearings can be used as the main bearings of crankshafts of internal combustion engines, compressors, etc., or large end bearings of connecting rods, where the bearing housing is less rigid than conventional ones due to weight reduction, etc. When placed in abutment against a substantially perfectly circular hole in the housing, the inner diameter of both half flat bearings gradually decreases from the center in the circumferential direction toward both ends before the bolts are tightened. Next, when the two halves of the housing are tightened with bolts, the compressive force applied to the two halves of the housing causes an elongation in the direction connecting the mating surfaces of the housing, causing both end faces of the half flat bearing to expand. The diameter of the knot increases. Then, the inner diameter of the half flat bearing becomes a substantially perfect circle and fits around the shaft.

〔Example〕

Embodiments of the half-split flat bearing according to the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 indicates a half-split flat bearing having a semi-cylindrical shape. Each numeral 2 represents an end surface that becomes a mating surface of a pair of half-split flat bearings 1. T is the wall thickness at the center in the circumferential direction,
T' is the wall thickness of both end faces 2, and the wall thickness of the half flat bearing 1 is determined from the wall thickness T of the center part to both end faces 2, 2 wall thickness
The thickness gradually increases to T'. Therefore, before assembly, the inner diameter of the half flat bearing 1 gradually decreases from the center in the circumferential direction toward both ends.

The wall thickness of this half-split flat bearing 1 is such that when it is assembled by tightening the bolts and nuts 5 shown in FIG. The inner diameter is expanded to compensate for the elongation in the direction connecting the surfaces, and is set so that the inner diameter becomes a substantially perfect circle.

The half-split flat bearing 1 is usually constructed by lining a back metal made of a steel plate with a bearing alloy, and further forming an overlay plating layer containing lead as a main component. In such a half flat bearing 1, the wall thickness is adjusted in one or both of the bearing alloy layer and the overlay plating layer.

Next, the effect will be explained.

FIG. 2 shows an embodiment in which the half flat bearing 1 is applied to a large end bearing of a connecting rod. Reference numeral 1 indicates half-split flat bearings which are arranged butt, 2 is an end face, 3 is a large end of the connecting rod, and 4 is a cap. It consists of a two-part housing. Note that the hole in the housing in which the pair of half flat bearings 1 are disposed butt against each other is formed into a substantially perfect circle before the half flat bearings 1 are assembled. Each number 5 is a bolt and nut for assembly.
In addition, the X-X axis is the both end surfaces 2, 2 of the half flat bearing 1
The Y-Y axis, which is the horizontal axis connecting the mating surfaces of the two halves of the housing, is the vertical axis passing through the center O of the half flat bearing 1.

Incidentally, the main bearing of the crankshaft has the same structure except that the portion corresponding to the rod side of the connecting rod's large end 3 is located on the cylinder block side of the internal combustion engine, for example.

The two-piece housing of the main bearing of the crankshaft or the big end bearing of the connecting rod as described above is difficult to ensure sufficient rigidity for reasons of weight reduction or structural reasons, and a relatively large tightening force is required for the bolts. If a pair of half flat bearings 1 are placed butt against each other in this housing, the inner diameter of both half flat bearings 1 can be adjusted from the center in the circumferential direction before the bolt/nut 5 is tightened. It gradually decreases towards both ends. Next, when the bolt/nut 5 is tightened, due to the compressive force F ₂ in the Y-Y axis direction,
The two-split housing extends in the direction connecting the mating surfaces (X-X axis direction) so as to enlarge the diameter of the hole that initially forms a substantially perfect circle, and along with the two half-split flat bearings 1, the X- The diameter expands in the X-axis direction.

Therefore, when assembling the two halves of the housing by tightening the bolts, each half of the flat is expanded so that the inner diameter expands to make a perfect circle by compensating for the elongation of the hole in the direction that connects the mating surfaces of the housing. Since the wall thickness of the bearings 1 is set, the inner diameters of the pair of half-flat bearings 1 are perfectly circular and fit into the shaft (not shown).

As a specific example of the half-split flat bearing 1, the wall thickness T at the center
is 2.00 mm, the wall thickness gradually increases toward both end faces 2, 2, and the wall thickness at a position of about 9.5 mm from the end face is about 2.008 mm, and this half flat bearing 1 is used for the crankshaft of a gasoline engine. It was applied to a crankshaft with a shaft diameter of 50 mm as the main bearing, and as a result of the durability test, there was no seizure and the contact between the shaft and the bearing was better than before.

[Effect of idea]

As can be understood from the above explanation, according to the half flat bearing according to the present invention, sufficient rigidity cannot be ensured due to weight reduction and structural reasons, and it is difficult to assemble with a relatively large tightening force. By applying it to the main bearing of the crankshaft of an internal combustion engine or compressor, or the big end bearing of a connecting rod, the inner diameter changes due to the tightening force of the housing, but the wall thickness does not change depending on the assembly. It is supplemented by a plain bearing and fits into the shaft. As a result, there is less risk of the wall thickness of the half-flat bearing changing during operation, resulting in excellent shaft support capacity, ensuring good oil lubrication during operation, and contributing to weight reduction of internal combustion engines, etc. . In addition, since the hole in the housing is initially formed into a substantially perfect circle, machining of the housing and the half flat bearing can be done easily and accurately.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one embodiment of a half-plane bearing according to the present invention, and FIG. 2 is an explanatory diagram of the operation of the same half-plane bearing applied to a large end bearing of a connecting rod. 1... Half flat bearing, 2... End face, 3... Big end of connecting rod, 4... Cap, 5... Bolt.
Nut, T... Thickness at the center, T'... Thickness at the end.

Claims (1)

[Scope of utility model registration request] A pair of half-split flat bearings that are disposed abutting against a substantially perfectly circular hole in a housing as a main bearing of a crankshaft or a large end bearing of a connecting rod,
The outer diameter of the bearing is formed by gradually increasing the wall thickness from the center toward both ends, based on the outer diameter of the arc before assembly, and the housing is divided into two parts. The wall thickness is set so that the inner diameter becomes a substantially perfect circle by compensating for the elongation of the hole in the direction connecting the mating surfaces of the housing when the housing is assembled by bolting. Split flat bearing.