JPH0874523A - Bearing device of cam shaft in internal combustion engine - Google Patents

Abstract

PURPOSE: To decrease thrust hammering sound by providing both thrust receiving projecting parts on both right and left sides in a bearing cap body on the part just above a cam shaft through a process of shortening their lengths in the direction perpendicular to an axis of the cam shaft. CONSTITUTION: Thrust receiving projecting parts 17b, 17c are provided on both right and left side surfaces in a bearing cap body 17 by forming thrust clearances D having the specific size between both thrust receiving projecting parts 17b, 17c and inner side surfaces 18a, 19a of both flange parts 18, 19 of a cam shaft 11. In this case, both thrust receiving projecting parts 17b, 17c are provided on the parts approximately just above the cam shaft 11 by reducing their lengths H in the direction perpendicular to the axis of the cam shaft 11 into smaller than the diameter of a journal part 12. Thereby, the thrust clearances to be preset can be made smaller between both thrust receiving projecting parts 17b, 17c and the inner side surfaces 18a, 19a in both flange parts 18, 19, thereby thrust hammering sound can be decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camshaft bearing device for a cylinder head of an overhead camshaft type internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, this type of bearing device has been known, for example, as follows.
As described in Japanese Utility Model Laid-Open No. 62-8424, and FIG.
~ As shown in FIG. 8, the journal portion 2 on the camshaft 1
Is a semi-circular bearing hole 4a provided in the bearing portion 4 on the cylinder head 3 side and a semi-circular bearing hole 7a provided in a bearing cap body 7 fastened to the bearing portion 4 by a pair of left and right bolts 5 and 6. And the thrust cap projections 7b, 7 on the left and right sides of the bearing cap body 7.
c is a semicircular bearing hole 7 in the bearing cap body 7.
While being provided so as to extend along the entire circumference of a, the thrust receiving flange portions 8 and 9 are provided on both sides of the journal portion 2 of the cam shaft 1, and the inner side surfaces 8a and 9a of the both flange portions 8 and 9 are the same. By providing thrust bearing projections 7b and 7c on both the left and right sides of the bearing cap body 6 so as to be close to each other with a thrust clearance D having an appropriate gap dimension, the axial load on the camshaft 1, that is, the thrust. It is configured to support the load.

[0003]

In the conventional bearing device, the thrust load on the cam shaft is applied to the cylinder head 3.
The bearing cap body 7 fastened to the bearing portion 4 on the side by a pair of bolts 5 and 6 is used to support the bearing portion 4 between the bearing cap 7 and the bearing portion 4. Providing a knock pin 10 that fits both,
As described in Japanese Utility Model Laid-Open No. 62-8424, the bearing cap body 7 is fitted into the bearing portion 4 so that the bearing cap body 7 is located on the cylinder head 3 side. Although the bearing cap body 7 is fixed with respect to No. 4, when the bearing cap body 7 is fixed, there is a dimensional error in the attachment position of the knock pin and backlash, or a dimensional error in the fitting and backlash. The bearing cap body 7 may be fixed in a state of being inclined with respect to the axis of the cam shaft 1 as shown by a two-dot chain line in FIG. 5 in a plan view.

Therefore, thrust receiving projections 7b and 7c are formed on both left and right sides of the bearing cap body 7 so as to extend along the entire circumference of the semicircular bearing hole 7a in the bearing cap body 7 as in the conventional case. In the configuration of providing, since the lateral width dimension of the thrust receiving projections 7b and 7c in plan view is large as L, the bearing cap body 7 is cammed by the dimension error and rattling as described above. When fixed by being inclined with respect to the axis of the shaft 1, the thrust receiving projections 7b, 7c and the inner side surfaces 8a, 9a of the thrust receiving flanges 8, 9 of the camshaft 1 are fixed. Thrust clearance will either be eliminated or reduced to be smaller.

Also in this case, in order to secure a predetermined thrust clearance D, between the thrust receiving projections 7b and 7c and the inner side surfaces 8a and 9a of the thrust receiving flange portions 8 and 9, Since the thrust clearance D initially set must be increased in advance by the amount of reduction as described above, the camshaft 1
There is a problem in that the rattling increases in the direction of the axis line, which causes an increase in thrust striking sound generated during this period.

An object of the present invention is to solve this problem as easily as possible without inviting a complicated structure.

[0007]

In order to achieve this technical object, the present invention relates to a semi-circular bearing hole in which a journal portion of a cam shaft is provided in a bearing portion on the cylinder head side and the bearing portion. The bearings are fastened by a pair of bolts and are supported by semi-circular bearing holes provided in the cap body, while thrust bearing flanges are provided on both sides of the journal portion of the camshaft and the inner surface of the flange portions and the bearing. In a bearing device for a camshaft, which is provided so as to provide a thrust clearance between the thrust receiving projections on the left and right sides of the cap body, both thrust receiving projections on the left and right sides of the bearing cap body are provided.
The length of the cam shaft in a direction perpendicular to the axis of the cam shaft is shortened at a position just above the cam shaft. "."

[0008]

[Operation] As described above, the thrust receiving projections on both sides of the bearing cap body are provided substantially right above the camshaft with a length perpendicular to the axis of the camshaft shortened. Thus, when the bearing cap body is fixedly attached to the bearing portion on the cylinder head side by a knock pin or fitting, there is a dimensional error in the attaching position of the knock pin and rattling, or a dimensional error in the fitting and rattling. When the bearing cap body is fixed in a state of being inclined with respect to the axis of the cam shaft in plan view due to attachment or the like, the thrust receiving projections are provided on the inner side surfaces of the flanges of the cam shaft. Since it is possible to limit the approaching to a slight extent, the amount of space between the thrust receiving projections and the inner side surfaces of the flanges is reduced by this amount. The thrust clearance set in advance can be reduced.

[0009]

As described above, according to the present invention, it is possible to reduce a preset thrust clearance between the thrust receiving projections of the bearing cap body and the inner side surfaces of the thrust receiving flange portions of the cam shaft. Therefore, the cam shaft can be pivotally supported in a state in which the thrust movement in the axial direction is reduced, and the thrust striking sound can be significantly reduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to the drawings of FIGS. In the figure, reference numeral 11 indicates a cam shaft, and the cam shaft 11 is provided with its journal portion 12 and, on both sides of this journal portion 12, thrust receiving flange portions 18 and 19. Either one or both of the thrust receiving flange portions 18 and 19 are used for attaching a timing gear, a timing belt pulley, or a timing chain sprocket to the cam shaft 11, or from one cam shaft to the other cam. It may also be used as a mounting part for the gear for transmitting rotation to the shaft.
Reference numeral 13 indicates a cylinder head, and the cylinder head 13 has a journal portion 12 on the cam shaft 11.
A bearing portion 14 having a semi-circular bearing hole 14a into which the lower half of the bearing is fitted is integrally provided.

Further, reference numeral 17 denotes a bearing cap body having a semicircular bearing hole 17a into which the upper half of the journal portion 12 of the cam shaft 11 is fitted, and the bearing cap body 17 is provided in the cylinder head 13. The bearing cap 14 is fastened to the upper surface of the bearing portion 14 with a pair of left and right bolts 15 and 16. At the time of fastening, the bearing cap 1
The bearing cap body 1 is provided between the bearing cap body 7 and the bearing portion 14 by providing a knock pin 20 which is fitted to both of them.
7 is fixed to the bearing portion 14.

Thrust receiving projections 17b and 17c are formed on the left and right side surfaces of the bearing cap body 17, respectively.
The thrust receiving projections 17b and 17c, and the inner side surfaces 18a of the flanges 18 and 19 of the camshaft 11.
When a thrust clearance D having a predetermined clearance is provided between the thrust receiving projections 17a and 19a, the thrust receiving protrusions 17b and 17c are provided at a portion substantially above the cam shaft 11.
The length H of the cam shaft 11 in the direction perpendicular to the axis is shortened so as to be equal to or smaller than the diameter of the journal portion 12, for example.

As described above, the thrust receiving projections 17b and 17c on both sides of the bearing cap body 17 are provided at a portion substantially right above the cam shaft 11 and have a length H perpendicular to the axis of the cam shaft 11. For example, when the bearing cap body 17 is fixedly attached to the bearing portion 14 on the cylinder head 13 side by the knock pin 20, the mounting position of the knock pin 20 is set by making the journal portion 12 shorter than the diameter of the journal portion 12. Due to the dimensional error and rattling of the cam shaft 1, the bearing cap body 17 has a camshaft 1 as shown by a two-dot chain line in FIG. 1 in a plan view.
In the case where the thrust receiving projections 17b and 17c are fixed in a state of being inclined with respect to the axis of No. 1, the inner surface 18 of the flanges 18 and 19 of the cam shaft 11 is fixed.
Since it is possible to minimize the approach to a and 19a, the thrust receiving protrusions 17 for both the thrusts are correspondingly reduced.
Inner side surface 1 of b, 17c and both flange portions 18, 19
It is possible to reduce the thrust clearance D that is preset between 8a and 19a.

[Brief description of drawings]

FIG. 1 is a plan view of a bearing device according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is an exploded perspective view of a bearing device according to an embodiment of the present invention.

FIG. 5 is a plan view of a conventional bearing device.

6 is a sectional view taken along line VI-VI of FIG.

7 is a sectional view taken along line VII-VII of FIG.

FIG. 8 is an exploded perspective view of a conventional bearing device.

[Explanation of symbols]

11 camshaft 12 journal part 13 cylinder head 14 bearing part 14a bearing semicircular bearing hole 15 and 16 bolt 17 bearing cap body 17a bearing cap body semicircular bearing hole 18 and 19 thrust bearing flange portion 20 knock pin 17b and 17c Thrust receiving protrusion

Claims (1)

[Claims] 1. A semicircular bearing hole formed in a bearing portion on a cylinder head side of a journal portion of a camshaft, and a semicircular bearing hole formed in a bearing cap body fastened to the bearing portion by a pair of bolts. On the other hand, the thrust bearing flange portions are provided on both sides of the journal portion of the cam shaft while being supported by the thrust clearance between the inner side surfaces of the both flange portions and the thrust receiving protrusion portions on the left and right sides of the bearing cap body. In the bearing device for the cam shaft, which is provided so as to open, the thrust receiving protrusions on both the left and right sides of the bearing cap body are provided at a portion substantially right above the cam shaft in a direction perpendicular to the axis of the cam shaft. A bearing device for a cam shaft in an internal combustion engine, characterized in that it is provided with a short length.