JPH07119429A - Cam shaft bearing structure for valve system - Google Patents

Abstract

PURPOSE:To progress the downsizing of a bearing body while ensuring lubricating performance and rigidity. CONSTITUTION:A halved type cam bracket 2 coupled with the bearing part on a cylinder head 1 side to support a cam shaft is provided, a bearing face 20 for supporting the cam shaft is formed on the cam bracket 2, leg parts 2A are provided on both sides nipping the bearing face 20, and through-holes 21, 22 for inserting fastening members with the cylinder head 1 are formed on the leg parts 2A. Further, a lubricating oil passage 3 is formed in a position between the through-hole 22 and the bearing face 20 on the connecting face of the leg part 2A with the cylinder head 1, both end opening parts 31, 31 of the lubricating oil passage 3 are opened to the bearing face 20 from the direction orthogonal to the cam shaft, and a curved part 33 is formed in the course of the lubricating passage for mutually connecting both the opening parts 31, 31 in such a manner as to avoid the through-hole 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a bearing structure of a camshaft which constitutes a valve train of an internal combustion engine.

[0002]

2. Description of the Related Art As a bearing for a camshaft which drives a valve train of an internal combustion engine, a journal bearing is widely used, which supports the camshaft with an oil film formed between the camshaft and the bearing. Such a camshaft bearing is, as shown in FIGS. 5A and 5B, a semicircular bearing that is in sliding contact with a camshaft (not shown) on the inner circumference of the arched half-split bearing 90. A surface 91 is formed and this bearing surface 9
Through holes 92, 92 for inserting bolts are formed in the leg portions 90A, 90A that come into contact with the bearing portion of the cylinder head (not shown) on both sides with the bearing 1 interposed therebetween, and the bearing 90 is shown through the through hole 92. It is fastened to the joint surface of the cylinder head with a bolt. These legs 90A, 90A
In order to supply the lubricating oil to the bearing surface 91, lubricating oil passages 93, 93 each having a substantially U-shape are engraved at a predetermined depth on the bottom surface of the lubricating oil passage 93. Of the discharge passages 93A and 93A opening to the bearing surface 91 so as to be orthogonal to the axis of the camshaft, and a passage 93B which connects these and is parallel to the axis of the camshaft and arranged between the bearing surface 91 and the through hole 92. To be done.

Lubricating oil supply holes are formed corresponding to the lubricating oil passages 93 on the joint surface (not shown) of the cylinder head with which the leg portions 90A of the bearing 90 abut, and the lubricating oil is provided on the bearing 90 fastened to the cylinder head. Lubricating oil is pumped from the supply hole to the lubricating oil passage 93. The lubricating oil is discharged from the discharge passages 93A, 93A opened to the bearing surface 91 via the passage 93B in a direction orthogonal to the camshaft axis, and forms an oil film having a predetermined thickness necessary to support the camshaft. In addition, such a camshaft bearing structure has been disclosed in Japanese Utility Model Sho 63-1.
The one disclosed in Japanese Patent No. 23712 is also known.

[0004]

To reduce the size and weight of the bearing 90, the distance L between the axis of the camshaft and the through hole 92 is reduced.
And the leg 9 surrounded by the lubricating oil passage 93.
There is a method of shortening the island portion 90B, which is the bottom surface of the 0A, in the entire length direction of the bearing 90 (direction of the interval L) to shorten the interval between the through holes 92, 92 for size reduction.

However, in the camshaft bearing structure of the conventional valve operating system described above, when the island portion 90B is shortened in the entire length direction of the bearing 90 in order to shorten the interval L, the leg portion 90A is formed by the lubricating oil passage 93. Not only the rigidity of the island portion 90B separated from the bottom surface of the island lowers, but also when the bearing surface 91 is processed, galling occurs on the island portion 90B. On the other hand, the rigidity of the island portion 90B is secured. Therefore, when the discharge passage 93A of the lubricating oil passage 93 is inclined, the lubricating oil is not supplied in the direction orthogonal to the axis line, flows out in the axial direction of the camshaft, and a predetermined oil film is not formed on the bearing surface 91, which causes poor lubrication. Sometimes caused.

Therefore, the present invention has been made in view of the above problems, and provides a camshaft bearing structure for a valve train which is capable of promoting downsizing and weight reduction of the bearing while ensuring lubrication performance and rigidity. With the goal.

[0007]

SUMMARY OF THE INVENTION According to the present invention, there is provided a half-divided bearing main body which supports a camshaft in pairs with a bearing portion on the cylinder head side, and the bearing main body has a bearing surface for supporting the camshaft. A leg portion is provided on both sides of the bearing surface, and a through hole for inserting a fastening member with the cylinder head is formed in the leg portion, and the through hole is formed on the joint surface of the leg portion with the cylinder head. In a camshaft bearing structure of a valve gear, which is configured to form a lubricating oil passage located between the bearing surface and guide the lubricating oil supplied from the cylinder head side through the lubricating oil passage to the bearing surface. While opening both ends of the lubricating oil passage in the bearing surface from a direction orthogonal to the camshaft, a curved portion is formed in the middle of the lubricating oil passage connecting these openings so as to avoid the through hole. .

[0008]

Therefore, the middle of connecting both ends of the lubricating oil passage formed in the leg portion of the bearing is curved so as to avoid the through hole provided in the leg portion of the bearing body, and both ends of the lubricating oil passage are connected to the camshaft. Since the bearing surface is opened in the orthogonal direction, the area of the bottom surface of the bearing leg surrounded by the lubricating oil passage is secured and the clearance between the shaft of the camshaft and the through hole is reduced without decreasing the rigidity of the bearing. The overall length can be shortened, and the lubricating oil pumped to the lubricating oil passage is discharged from the opening on the bearing surface in the direction orthogonal to the axis of the camshaft, and the radial hydraulic pressure is applied to the camshaft. An oil film having a predetermined thickness is formed on the bearing surface, so that the camshaft can be smoothly supported.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a cylinder head 1 of an OHC engine.
The cam bracket 2 and the cam bracket 82 as the bearing main body fastened to the girinder head 1 support a cam shaft (not shown), and are freely slidable in the valve hole 11. The supported intake valve (not shown) is driven by the camshaft.

As shown in FIG. 2, the cam bracket 2 for supporting the camshaft is a half type formed in an arch shape.
A semicircular bearing surface 20 that is in sliding contact with a cam shaft (not shown) is formed on the inner circumference.

A cam bracket 2 sandwiching this bearing surface 20
On both sides of the legs 2A, 2A abutting the cylinder head 1
Is provided. Through holes 21 and 22 are formed in the leg portions 2A and 2A so as to vertically penetrate the leg portion 2A of the cam bracket 2 for inserting bolts, and the bottom surface of the leg portion 2A as a joint surface and the cylinder head 1 are joined together. The cam bracket 2 is fastened to the cylinder head 1 by abutting the end faces (not shown) and bolts (not shown) as fastening members inserted into the through holes 21 and 22, respectively.

The cam bracket 2 is arranged in a direction orthogonal to the axis of the cam shaft, the through hole 21 is inside the cylinder head 1 (left in FIG. 1), and the through hole 22 is outside the cylinder head 1 (FIG. It is fastened at a predetermined position (on the right side of 1). Although not shown, a half-divided bearing surface is also formed on the cylinder head 1 facing the cam bracket 2, and the cam shaft is supported between the cam bracket 2 and the cylinder head 1.

As shown in FIGS. 3 and 4, a lubricating oil passage 3 is engraved in a groove shape having a predetermined depth on the bottom surface of the leg portion 2A having the through hole 22, and both end portions of the lubricating oil passage 3 are formed. Form openings 31, 31 opened at the bearing surface 20, and these openings 31,
31 is a through hole 2 with a predetermined interval in the axial direction of the camshaft.
They are arranged symmetrically with respect to the center line connecting the first and the second lines.

The lubricating oil passage 3 has openings 31, 31 at both ends.
A curved portion 32 that bends in the direction along the bearing surface 20 after going to the inner circumference of the leg portion 2A from the toe, and a curve formed between the through hole 22 and the bearing surface 20 by connecting the curved portions 32, 32. The island portion 2B is formed on a part of the bottom surface of the leg portion 2A that is configured by the portion 33 and is partitioned by the lubricating oil passage 3.

The lubricating oil passage 3, which has once gone from the opening 31 toward the inner circumference of the leg 2A, is bent in the direction along the bearing surface 20 from the inner circumference of the leg 2A at the arc-shaped bent portion 32, and then the opening. Three
A curved portion 33 that is curved toward the bearing surface 20 is formed at a substantially central portion of the first and the third portions 31 and away from the through hole 22, and the opening portion 31 at the other end is formed from the curved portion 33 through the bent portion 32.
Connected to.

The opening 31 opens from the arcuate bent portion 32 in a direction orthogonal to the axis of the cam shaft (not shown), and the lubricating oil pumped into the lubricating oil passage 3 is perpendicular to the bearing surface 20, that is, shown in the drawing. Discharge in the radial direction of the camshaft.

With the above construction, the operation will be described.

The cam bracket 2 is fastened to the cylinder head 1 with bolts (not shown) inserted through the through holes 21 and 22, and is in sliding contact with the cam shaft (not shown) at the bearing surface 20.

As shown also in FIG. 1, the lubricating oil is discharged at a predetermined position facing the bent portion 32 of the lubricating oil passage 3 to the end surface of the cylinder head 1 with which the bottom surface of the leg portion 2A of the cam bracket 2 abuts. The supply hole 12 opens.

Lubricating oil pumped by a pump (not shown) when the engine is started is supplied from the supply hole 12 to the bent portion 32 of the lubricating oil passage 3.

Lubricating oil is discharged from the bent portion 32 to the cam shaft (not shown) through the opening 31 at one end of the lubricating oil passage 3, while the lubricating oil is discharged from the opening 31 at the other end through the curved portion 33 and the bent portion 32. Similarly, it is discharged toward the camshaft.

Lubricating oil discharged from the opening 31 is discharged at a right angle to the bearing surface 20, that is, in a direction orthogonal to the axis of the camshaft, and the camshaft has the bearing surface 20.
Supported by an oil film having a predetermined thickness formed in accordance with the oil pressure of the lubricating oil. Since the lubricating oil is discharged from the opening 31 in the direction orthogonal to the axis of the camshaft, the lubricating oil can be prevented from flowing out in the axial direction of the camshaft and a good oil film can be formed.

The curved portion 33 provided in the middle of the lubricating oil passage 3 not only smoothly connects the bent portions 32, 32, but also bends the lubricating oil passage 3 to the bearing surface 20 so that the through hole 22 and the lubricating oil passage The through hole 22 can be brought as close as possible to the bearing surface 20 while avoiding interference with the through hole 21, 2.
The interval between the two can be shortened, and the cam bracket 2 forming the bearing body can be downsized.

Further, the thickness of the island portion 2B separated from the bottom surface of the leg portion 2A by the lubricating oil passage 3 (through holes 21, 22).
Is the thinnest on the center line connecting the through holes 21 and 22, but the wall thickness increases in accordance with the curved portion 33 as it goes toward the opening 31, and therefore the island portion 2
Although B has a thin portion, it is possible to obtain a predetermined rigidity by ensuring a predetermined area, and no galling occurs when cutting the bearing surface 20, thus improving workability. You can

In this way, after the lubricating oil passage 3 formed in the leg portion 2A of the cam bracket 2 is opened in the bearing surface 20 in the direction orthogonal to the axis of the camshaft, the arcuate bent portion 32 extends along the bearing surface 20. Bend in the direction
3 is curved so as to be close to the bearing surface 20 so as to avoid the through hole 22, the interval between the through holes 21 and 22 can be shortened, the cam bracket 2 can be downsized, and the lubricating oil passage 3 The island portion 2B forming a part of the bottom surface of the leg portion 2A partitioned by is capable of ensuring a predetermined rigidity, and does not cause galling when the bearing surface 20 is cut. Since the lubricating oil is discharged from the opening 31 in the direction orthogonal to the axis of the cam shaft, a good oil film is formed on the bearing surface 20 to suppress the flow of the lubricating oil in the axial direction of the cam shaft. The shaft can be lubricated smoothly.

In the above embodiment, the lubricating oil passage 3
Although it is formed on the leg portion 2A on the side of the through hole 22, it can be formed on the leg portion 2A having the through hole 21.

Further, the curved portion 33 and the openings 31, 3 at both ends are provided.
Although the connection with 1 is made by the arc-shaped bent portion 32, it is not limited to the arc shape, and the lubricating oil passage 3 in the opening 31 may be arranged in a direction orthogonal to the axis of the cam shaft. Good.

[0029]

As described above, according to the present invention, the lubricating oil passage forming the leg portion of the bearing body is opened in the bearing surface in the direction orthogonal to the axis of the camshaft, and then the penetrating portion provided in the leg portion is penetrated. Since it is curved so as to avoid holes, the spacing between the through holes formed on both sides of the bearing surface can be shortened, which can promote downsizing of the bearing body, and the leg section partitioned by the lubricating oil passage The bottom surface can secure a certain rigidity, and no galling occurs when cutting the bearing surface, and the lubricating oil is discharged from the opening in the direction orthogonal to the axis of the camshaft. Therefore, the lubricating oil that flows out in the axial direction of the camshaft can be suppressed, and a good oil film can be formed on the bearing surface to smoothly lubricate the camshaft.

[Brief description of drawings]

FIG. 1 is a sectional view of a bearing body showing an embodiment of the present invention.

FIG. 2 is a front view of a cam bracket.

FIG. 3 is a view taken along the line AA of FIG.

4 is a cross-sectional view taken along the line BB of FIG.

FIG. 5 is a front view and a bottom view of a conventional bearing.

[Explanation of symbols]

 2 Cam bracket 2A Leg part 3 Lubricating oil passage 20 Bearing surface 21, 22 Through hole 31 Opening part 32 Bending part 33 Bending part

Claims (1)

[Claims] 1. A half-divided bearing body for supporting a camshaft is provided, which is paired with a bearing portion on the cylinder head side, and a bearing surface for supporting the camshaft is formed on the bearing body.
Leg portions are provided on both sides of the bearing surface, and a through hole for inserting a fastening member with a cylinder head is formed in the leg portion, and the through hole and the bearing surface are formed on the joint surface of the leg portion with the cylinder head. In a camshaft bearing structure of a valve gear, wherein a lubricating oil passage is formed between the lubricating oil passage and the lubricating oil supplied from the cylinder head side through the lubricating oil passage is guided to the bearing surface. Both end openings of the passage are opened to the bearing surface in a direction orthogonal to the camshaft, and a curved portion is formed in the middle of a lubricating oil passage connecting the both openings so as to avoid the through hole. Camshaft bearing structure for valve train.