GB2142972A

GB2142972A - Fuel injection nozzles for internal combustion engines

Info

Publication number: GB2142972A
Application number: GB08411652A
Authority: GB
Inventors: Dorian Farrar Mowbray
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1983-07-09
Filing date: 1984-05-08
Publication date: 1985-01-30
Also published as: ES532699A0; ES8504340A1; FR2548735A1; GB8411652D0; IT1212096B; JPH0514106B2; DE3423592A1; GB8318635D0; GB2142972B; FR2548735B1; DE3423592C2; US4635853A; IT8421058A0; JPS6069260A

Description

1 GB 2 142 972 A 1

SPECIFICATION

Fuel injection nozzles This invention relates to a fuel injection nozzle for supplying fuel to an internal combustion engine and of the kind comprising a nozzle body having a bore formed therein, a seating defined at one end of the bore and a resiliently loaded valve member slidable in the bore and shaped for co-operation with the seating, said valve member being urged into contact with the seating by the resilient loading and being lifted from the seating by the action of fuel under pressure to allow fuel flow from an inlet to an outlet.

It is conventional practice to form in the bore an enlargement which is connected to a fuel inlet by way of a drilling formed in the body. The formation of the enlargement in the bore and also the drilling pose manufacturing problems and in addition, the drilling since it runs alongside the bore, requires that the wall thickness between the wall of the bore end the exterior of the body must be sufficient to accommodate the drilling and also to provide adequate wall thickness to withstand the high fuel pressure.

The object of the present invention is to provide a fuel injection nozzle of the kind specified in a simple and convenient form.

According to the invention in a fuel injection nozzle of the kind specified said bore is defined in a sleeve mounted in an elongated recess in the body said sleeve terminating short of the end of the recess to define between the end of the sleeve and the end of the recess, an enlargement, the outer wall of the sleeve and the wall of the recess defining a passage through which fuel can flow to said enlargement from said inlet, the fuel under pressure in the enlargement acting upon said valve member to lift the valve member away from the seating.

An example of a fuel injection nozzle in accord- ance with the invention will now be described with reference to the accompanying drawings, in which:

Figure 1 shows a conventional form of nozzle in sectional side elevation, Figure 2 shows the body of the fuel injection 110 nozzle modified in accordance with the invention, and Figure 3 is a plan view of part of the modified body seen in Figure 2.

Referring to Figure 1 of the drawings the nozzle comprises a body 10 of stepped form the narrower end of the body in use being exposed within a combustion space of an associated engine. The nozzle body in practice is secured to a support member or holder by means of a cap nut and formed 120 within the body is a blind bore 11 and this extends from the wider end of the body to adjacent the narrower end thereof. At the blind end of the bore there is defined a seating 12 about an outlet opening 13. Intermediate the ends of the bore the latter is provided with an enlargement 14 which communicates with a fuel inlet convenienly formed in the aforesaid holder, by way of an inlet passage 15. The inlet passage 15 runs alongside the bore 11 to the wider end of the body and in use, is connected to the outlet of a fuel injection pump 16.

Located within the bore is a valve member 17 which at its end adjacent the seating is shaped to co-operate with the seating. This end of the valve member also mounts an extension 18 which projects with clearance through the outlet opening 13. The portion of the valve member which is disposed between the enlargement and the blind end of the bore is of reduced diameter to define an annular clearance 19 which communicates with the enlargement 14 to permit passage of fuel from the enlargement through the opening 13 when the valve member is lifted from its seating.

At its end remote from the seating the valve member is provided with a peg 20 which carries a spring abutment 21, the latter being engaged by a coiled compression spring 22. The spring is mounted within a vented chamber defined in the aforesaid holder. In operation, fuel under pressure supplied to the enlargement 14 acts on the differential area of the valve member to create a force which acts to move the valve member against the action of the spring. When the force exerted by the spring is overcome the valve member is lifted from its seating to allow fuel flow through the annular clearance defined between the extension 18 and the wall of the opening 13. The extension is profiled to control the fuel flow through the opening and may also be profiled to alter the shape of the fuel spray andlor the rate at which fuel can flow.

The formation of the enlargement 14 in the bore and also the passage 15 present manufacturing problems. In addition, the fact that the passage 15 extends alongside the bore 17 means that the wall thickness between the wall of the bore and the exterior of the body must be sufficiently large to accommodate the passage.

The manufacturing problems are reduced by, as shown in Figure 2, supporting the valve member within a bore formed in a sleeve 23 which is supported in a drilling 24 in the body. The bore in the sleeve is conveniently substantially the same diameter as the lower portion of the bore 11 which is formed in the same manner as hithertofore. The sleeve 23 is formed from a hardwearing material and the equivalent of the enlargement 14 is defined between the inner end of the sleeve and the step between the drilling 24 and the bore 11. The sleeve is retained within the drilling in any convenient man- ner. For example, it may be an interference fit or it may be secured by some form of adhesive for example, an anaerobic adhesive. The sleeve can be formed from a ceramic material for example silicon nitride and the bore in the sleeve is machined after the sleeve has been inserted into the drilling.

In order to avoid the need for a separate passage 15, the external surface of the sleeve is provided with grooves indicated at 25 in Figure 3. These grooves communicate with a small recess 26 formed in the wider end of the body, the recess communicating with a passage in the aforesaid holder. The grooves 25 can be of any convenient section. Moreover, since in use, they will contain fuel at high pressure it is convenient in order to equalise the stress in the sleeve, to form the grooves in helical fashion. As a 2 GB 2 142 972 A 2 result of providing the grooves, the body can be of reduced diameter since it is no longer necessary to accommodate the passage 15. It also enables the. remaining portion of the body to be formed from a material which is better able to withstand impact loads at the seating 12. Moreover, if the material forming the sleeve is formed from an electrically insulating material the valve member in conjunction with the seating, can be used as a switch to provide an indication of when the valve member is lifted from its seating.

As described the nozzle is of the so-called "pintie type". It will be understood that the invention may be applied to a so-called "hole type" nozzle.

Claims

1. A fuel injection nozzle for supplying fuel to an internal combustion engine comprising a nozzle body having a bore formed therein, a seating defined at one end of the bore and a resiliently loaded valve member sUdable in the bore and shaped for co-operation with the seating, said valve member being urged into contact with the seating by the resilient loading and being lifted from the seating 90 by the action of fuel under pressure to allow fuel flow from an inlet to an outlet, a sleeve mounted in an elongated recess in the body, said bore being defined by said sleeve, the sleeve terminating short of the end of the recess to define between the end of the sleeve and the end of the recess, an enlargement, the outer wail of the sleeve and the wall of the recess defining a passage through which fuel can flow to said enlargement from said inlet, the fuel under pressure in the enlargement acting upon said valve memberto lift the valve member awayfrom the seating.

2. A nozzle according to Claim 1 in which said passage is in part defined by a groove formed in the outer wall of the sleeve.

3. A nozzle according to Claim 2 in which said groove is helical in form.

4. A fuel injection nozzle for supplying fuel to an internal combustion engine comprising the combination and arrangement of parts substantially as hereinbefore described with reference to Figure 1 as modified by Figures 2 and 3 of the accompanying drawings.

Printed in the UK for HMSO, D$818935,11184,7102. Published by The Patent Office, 25 Southampton Buildings, London, WC2A 1AV, from which copies maybe obtained.

4. A nozzle according to Claim 1 in which said sleeve is formed from a ceramic material.

5. A nozzle according to anyone of the preceding claims in which said sleeve is secured by adhesive within the recess.

6. A fuel injection nozzle for supplying fuel to an internal combustion engine comprising the corn- bination and arrangement of parts substantially as hereinbefore described with reference to Figure 1 as modified by Figures 2 and 3 of the accompanying drawings.

New claims or amendments to claims filed on 17 July 1984 Superseded claims 1-6 New or amended claims:- 1. A fuel injection nozzle for supplying fuel to an internal combustion engine comprising a nozzle body having a bore formed therein, a seating defined at one end of the bore and a resiliently loaded valve member slidable in the bore and shaped for co-operation with the seating, said valve member being urged into contact with the seating by the resilient loading and being lifted from the seating by the action of fuel under pressure to allow fuel flow from an inlet to an outlet, a sleeve mounted in an elongated recess in the body, said bore being defined by said sleeve, the sleeve terminating short of the end of the recess to define between the end of the sleeve and the end of the recess, an enlargement, the outer wall of the sleeve and the wall of the recess defining a passage through which fuel can flow to said enlargement from said inlet, the fuel under pressure in the enlargement acting upon said valve memberto liftthe valve member awayfrom the seating, said passage being in part defined by a helical groove formed in the outer wall of the sleeve.

2. A nozzle according to Claim 1 in which said sleeve is formed from a ceramic material.

3. A nozzle according to Claim 1 in which said sleeve is secured by adhesive within the recess.