GB2213197A

GB2213197A - I.C. engine fuel injector clamp

Info

Publication number: GB2213197A
Application number: GB8827423A
Authority: GB
Inventors: Derick Brian Payne
Original assignee: Perkins Engines Group Ltd
Current assignee: Perkins Engines Group Ltd
Priority date: 1987-12-05
Filing date: 1988-11-24
Publication date: 1989-08-09
Anticipated expiration: 2008-11-24
Also published as: GB2213197B; GB8827423D0

Abstract

A support bracket 7 with an upstanding support post 11 is connected to the engine 2 by a stud 9 and nut 10 and supports a clamp arm 6 with one end adapted to engage the support post at a point of rolling contact 20 and the other end adapted to engage the injector body 1 at a point of rolling contact 16. A nut 12 on the study 9 urges a part-spherical washer 13 to engage the arm 6 at an intermediate point to apply a clamping load. A tool (21, Fig. 4) comprising a guide member (22) that is inserted into the bore 3 for the injector 1 and a pair of arms (23) that engage either side of the support bracket 7, is used to orientate the bracket angularly about the stud 9. <IMAGE>

Description

INJECTOR CLAMP This invention relates to means for clamping a fuel injector in place on an engine.

The clamping force applied to an injector is ideally directed axially of the injector so that it seats squarely in the head at its inner end and forms a seal against leakage. Clamps have therefore been designed so as to avoid tilting the injector. For example, two-bolt clamps have straddled the injector and had the bolts either side of the injector uniformly tightened down, and the clamp has been shaped to provide a rolling point of contact with shoulders on the injector. Single-bolt clamps have also been shaped to provide a rolling point of contact with shoulders on the injector, but there is generally a greater tendancy to impart a lateral force to the injector because of the bolt being offset to one side of the injector.

Lateral clamping forces have an additional adverse affect with particular designs of injector, such as two-stage injectors, having internal axially moving components with fine tolerances that are sensitive to flexing of the injector body. Further, this problem is exacerbated by the generally increased length of two-stage injectors.

An object of the present invention is to provide injector clamping means which is suitable for use with longer, two-stage injectors and reduces or avoids the application of lateral forces to the injector body.

According to the invention, clamping means is provided comprising a support bracket with an upstanding support post, first fastening means for connecting the support bracket to the engine, a clamp arm with one end adapted to engage the support post at a point of rolling contact and the other end adapted to engage the injector body at a point of rolling contact, and second fastening means that engages the clamp arm at an intermediate point between its ends and co-operates coaxially with the first fastening means to apply a clamping load to the clamp arm.

In fastening the support bracket to the engine, the upstanding support post is orientated relative to the injector so that the clamp arm engages both. This is achieved using a special tool comprising a guide member that is inserted into the bore for the injector and has a pair of arms that engage either side of the support bracket to orientate it angularly about the first fastening means.

The invention will now be described by way of example with reference to the accompanying drawings in which: FIGURE 1 is a side elevation of an injector fitted with clamping means according to one embodiment of the invention, FIGURE 2 is a plan view of the injector and clamping means in the embodiment of Figure 1, FIGURE 3 is a part side elevation in the direction of arrow A in Figure 1, and FIGURE 4 is a plan view of a tool used to orientate the support bracket of the clamping means in Figure 1 during assembly.

Figure 1 shows a fuel injector 1 mounted in the cylinder head 2 of a diesel engine. The injector is received within a bore 3 in the head 2 and seals on a washer 4. Clamping means 5 holds the injector in place in the bore 3 and comprises a clamp member 6 mounted on a mounting bracket 7 above the head 2.

The bracket 7 has a base portion 8 that is fastened to the head 2 by a stud 9 and nut 10, and a mounting post 11 offset from the stud 9 that projects upwards from the base portion 8. The clamp member 6 is secured at an intermediate point to the stud 9 by a nut 12 and a hemispherical washer 13, and has opposite ends engaging the injector 1 and the top of the post 11. The end that engages the injector is bifurcated and has arms 14 with flat faces that closely co-operate with a pair of opposed flats 15 on the upper end of the injector 1. The arms 14 also have arcuate lugs 16 on their lower edges that engage shoulders 17 on the injector adjacent to said flats 15 so as to form points of rolling contact that lie in a plane through the axis of the injector so as to apply an axial clamping load to the injector.

The opposite end of the clamp member 6 tapers to a lug 18, which has an under-surface 19 that is rounded in a direction laterally of the longitudinal axis of the clamp member 6, as shown in Figure 3, so that the clamp member can rock laterally on the top of the post 11. The top of the post 11 tapers inwards to a surface 20 that is rounded in the direction of the longitudinal axis of the clamp member 6, as seen in Figure 1, so that the clamp member 6 can also rock longitudinally on the post 11. The clamp member 6 is therefore supported so that it can pivot at all points of contact with the injector 1, the mounting bracket 7,and the fastener 9, 12, 13, and thereby applies an axial load to the injector.

In order to ensure that the mounting bracket 7 is orientated correctly with the post 11, the stud 9 and the injector 1 are all symmetrically aligned in a common plane, as shown in Figure 2. A special tool 21 is employed during assembly of the mounting bracket 7 on the head 2, as shown in Figure 4.

This tool 21 comprises a cylindrical guide rod 22 that is inserted into the injector bore 3 in the head and has a pair of laterally extending arms 23 that engage either side of the mounting bracket and co-operate with opposed flattened sides 24 thereof to orientate the mounting bracket 7 in the required manner.

The injector 1 illustrated is a two-stage injector which is longer than a standard injector and has clamping shoulders 17 that are raised well above the top surface of the cylinder head 2 of the engine. The provision of the mounting bracket 7 with the upstanding mounting post 11 therefore accommodates the height of these clamping shoulders 17 and supports a simple form of clamp arm 6.

Claims

1. Clamping means for clamping a fuel injector in place on an engine comprising a support bracket with an upstanding support post, first fastening means for connecting the support bracket to the engine, a clamp arm with one end adapted to engage the support post at a point of rolling contact and the other end adapted to engage the injector body at a point of rolling contact, and second fastening means that engages the clamp arm at an intermediate point between its ends and co-operates coaxially with the first fastening means to apply a clamping load to the clamp arm.

2. Clamping means as claimed in claim 1 in which said other end of the clamp arm is bifurcated comprising a pair of arms in close co-operation with a pair of opposed flat surfaces on the injector.

3. Clamping means as claimed in claim 1 in which each of said pair of arms engages a corresponding shoulder on the injector adjacent to said flat surface.

4. Clamping means as claimed in any one of the preceding claims in which said one end of the clamp arm tapers to a lug with a curved under-surface that engages the top of the support post.

5. Clamping means as claimed in claim 4 in which said curved under-surface is curved laterally of the longitudinal axis of the clamp arm and in which the top of the support post is curved in the direction of said longtitudinal axis so that the clamp arm rolls both laterally and longitudinally on the support post.

6. A method of clamping a fuel injector in place on an engine comprising providing a support bracket with an upstanding support post, locating the support bracket by a first fastening means on the engine, orientating the support bracket angularly about the first fastening means using a tool comprising a guide rod that is inserted into the recess for the injector and has a pair of laterally extending arms that co-operate with sides of the support bracket, tightening said first fastening means, locating the injector in said recess, providing a clamp arm with one end to engage the support post at a point of rolling contact and the other end to engage the injector at a point of rolling contact, and providing second fastening means that engages the clamp arm at an intermediate point between its ends and co-operates coaxially with the first fastening means to apply a clamping load to the clamp arm.

7. Clamping means for clamping a fuel injector in place on an engine substantially as herein described with reference to the accompanying drawings.

8. A method of clamping a fuel injector in place on an engine substantially as herein described with reference to the accompanying drawings.