JPH09177637A - Bearing device of fuel injection pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the assembling property, and to reduce the vibration and noise by fitting a center bearing to a lower opening part of a pump housing in an in-line fuel injection pump through a shim of the prescribed thickness to a pump housing. SOLUTION: When a center bearing 2a having a face to support a lower half of a cam shaft 3 is fitted to an opening part open inside of a lower part of a pump housing 1 in an in-line fuel injection pump, and a flange part is fixed by bolts 4, a shim 5 of the prescribed thickness is interposed between the pump housing 1 and the center bearing 2a. The thickness of the shim 5 is the dimension of the distance between the pump housing 1 and the center bearing 2a when the center bearing 2a is pressed relative to the cam shaft 3 with the preset clearance C added thereto. The prescribed clearance C can be secured between the cam shaft 3 and the center bearing 2a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing device for a fuel injection pump, which is provided with a center bearing mainly for reducing noise of a row type fuel injection pump of a diesel engine.

[0002]

2. Description of the Related Art A conventional row fuel injection pump used in a diesel engine is known to have a center bearing for reducing noise. That is, as such a conventional example, as shown in FIG. 5 which is a side view showing the main part broken in FIG. 4 and a front sectional view of the main part in the AA direction of FIG. A half-moon-shaped center bearing 2 serving as a journal portion of the cam shaft 3 is fixed to the pump housing 1 from the lower side of the pump housing 1 with a bolt 4 so as to support the lower half of the cam shaft 3. .

The clearance between the center bearing 2 and the cam shaft 3 is usually 0.5 mm or less, and the noise of the fuel injection pump is reduced by viscous damping force generated by the relative speed between the two when the fuel injection pump is operating. Functioning. However, in this conventional example, after the center bearing 2 is assembled in the pump housing 1, a method of assembling the cam shaft 3 while avoiding the interference between the cam and the center bearing 2 is adopted from the lateral hole opened in the cam shaft housing. Therefore, there is a problem that the workability of attaching the cam shaft 3 to the pump housing 1 is poor.

Also, because of variations in the manufacturing precision of parts,
There is a problem that the clearance between the cam shaft 3 and the center bearing 2 cannot be set to a narrow clearance width, resulting in insufficient noise reduction. On the other hand, as a cover plate fitted to the bottom of the pump housing of the row fuel injection pump that pumps fuel by the reciprocating motion of the plunger in response to the rotation of the camshaft, it is possible to increase the radius of rotation of the camshaft on the inside surface of the cover. JP-A-4-25556 discloses an invention relating to a row-type fuel injection pump which has a recessed portion which is provided with a plurality of mounting screw holes in a thick portion around the recessed portion.
6 is proposed.

However, the object of the present invention is to increase the rigidity of the pump housing and the cover plate and to improve the airtightness inside the pump housing without increasing the mounting height of the fuel injection pump of the diesel engine. However, the clearance control between the cam shaft and the center bearing is not considered at all.

[0006]

SUMMARY OF THE INVENTION According to the present invention, the assemblability can be improved so that the center bearing can be assembled after the camshaft is assembled, and the clearance between the camshaft and the center bearing can be set within a narrow range.
An object of the present invention is to provide a bearing device for a fuel injection pump that can obtain a stable noise reduction effect.

[0007]

In order to achieve the above object, the present invention provides a shim having a predetermined thickness with respect to the pump housing in the lower opening of the row type fuel injection pump having a pump housing having an opening in the lower part. It is composed of a bearing device of a fuel injection pump having a center bearing attached thereto. Also, the center bearing is preferably formed integrally with a lower cover that covers the lower opening of the pump housing.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a bearing device for a fuel injection pump according to the present invention will be described below with reference to the drawings.
1 is a front sectional view of a main part of a pump housing having the center bearing attached, FIG. 2 is a plan view of the pump housing seen from the lower surface of FIG. 1, and FIG. FIG.

First, in this fuel injection pump, as in the conventional example shown in FIG. 4, a center bearing 2a is formed in an opening portion which opens inside the lower portion of the pump housing 1 of the row type fuel injection pump.
Is provided. As shown in FIG. 1, a center bearing 2a having a surface for supporting the lower half of the cam shaft 3 is attached to the lower opening of the pump housing 1 with a bolt 4. A shim 5 is interposed between the pump housing 1 and the center bearing 2a in order to set a predetermined clearance between the cam shaft 3 and the center bearing 2a.

The thickness of the shim 5 is such that when the center bearing 2a is pressed against the cam shaft 3 supported on the lower portion of the pump housing 1 as shown in FIG. At a distance d from 2a,
The setting clearance C shown in FIG. 1 is added. Further, in order to prevent oil leakage, an O-ring 6 is provided on the outer peripheral surface of the center bearing 2a on the mating surface with the pump housing 1.

In this embodiment shown in FIG. 1, the center bearing 2a is provided on the pump housing 1 through a shim 5 having a predetermined thickness.
Pump housing 1 with bolts 4 to attach a
Attach the lower cover part to the center bearing 2
Although it is formed integrally with a, the part B of the lower cover to which the bolt 4 is tightened may be formed separately from the center bearing 2a, and may be connected with a bolt.

[0012]

According to the bearing device for a fuel injection pump of the present invention described above, after the cam shaft is assembled,
Since the center bearing is assembled, the ease of assembly of both is very good. Further, since the clearance can be set within a narrow range between the cam shaft and the center bearing, a stable vibration and noise reduction effect of the fuel injection pump due to the viscous damping force generated between the two can be obtained.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a main part of a pump housing to which a center bearing is attached in an embodiment of a bearing device for a fuel injection pump of the present invention.

FIG. 2 is a plan view seen from the lower surface of FIG.

FIG. 3 is a schematic front cross-sectional view showing a clearance between the pump housing and the center bearing of FIG.

FIG. 4 is a side view showing a main part of a fuel injection pump of a conventional example broken away.

5 is a front sectional view of a main part in the direction AA of FIG.

[Explanation of symbols]

1 Pump housing 2a Center bearing 5 Shim

Claims (2)

[Claims] 1. A bearing device for a fuel injection pump, wherein a center bearing is attached to the opening of a row-type fuel injection pump having a pump housing with an opening at the bottom through a shim having a predetermined thickness with respect to the pump housing. 2. The bearing device for a fuel injection pump according to claim 1, wherein the center bearing is integrated with a lower cover that covers a lower opening of the pump housing.