GB2144178A

GB2144178A - I.C. engine fuel injector

Info

Publication number: GB2144178A
Application number: GB08416285A
Authority: GB
Inventors: Paul Stuart Renowden
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1983-07-28
Filing date: 1984-06-26
Publication date: 1985-02-27
Also published as: GB8416285D0; GB2144178B

Abstract

An outlet sleeve 15 has a jet of fuel therethrough directed from an outlet orifice the flow through which is controlled by a solenoid operable valve (24, Fig. 1). The jet of fuel impinges upon a target and is broken up to facilitate the mixing of the fuel with air. The target may be in the form of a conical body 29 which is supported in the sleeve by wires 30 and has its apex directed towards the outlet orifice or in the form of triangular section wires 32. The sleeve and target may be an integral plastics moulding. <IMAGE>

Description

SPECIFICATION Fuel injector This invention relates to a fuel injector of the kind comprising an injector body, a fuel inlet defined in the body, means defining a fuel outlet orifice, valve means for controlling fuel flow through the orifice, and a solenoid device for controlling the operation of the valve means, said orifice when fuel flows therethrough producing a jet of fuel.

In some applications of the injector for example where petrol is delivered to an inlet manifold of an engine, it is desirable that the fuel spray should be broken up to facilitate mixing of the petrol with the air flowing to the engine.

The object of the invention is to provide a fuel injector of the kind specified in a form in which this desideratum is achieved.

According to the invention in a fuel injector of the kind specified there is disposed downstream of the fuel outlet orifice a target member upon which the fuel leaving the orifice impinges, said target acting to break up the jet of fuel.

One example of a fuel injector in accordance with the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a longitudinal sectional view of a fuel injector for an internal combustion engine, Figure 2 is a view to an enlarged scale of part of the injector seen in Figure 1, Figure 3 is a plan view to an enlarged scale of part of the injector not seen in Figure 1, and Figure 4 is a view similar to Figure 3 showing a modification.

Referring to the drawings, the injector comprises a hollow generally cylindrical stepped multi part body 11 formed from magnetisable material and defining a fuel inlet 12 at one end thereof. Within the body there extends a magnetisable and hollow flanged core 13 through which extends a passage 14 which connects the inlet 12 with an outlet 15 of the body. Surrounding the core 13 within the body is a former 16 formed from synthetic resin material upon which is wound a solenoid winding 17. The outlet which is in the form of a sleeve retained within the narrower end of the body, projects in use into the inlet manifold of an engine.

Adjacent the outlet the body 11 defines an integral radially inwardly extending circumferential shoulder 18 against which a steel annulus 19 is trapped by a valve seat member 21 which in the particular example is formed from steel. The valve scat member 21 is in the form of a disc the diameter of which is equal to the internal diameter of the body 11, the disc having a centrally disposed outlet orifice 22. The core 13 terminates short of the valve seat member 21 and an annular clearance exists between the core and the inner face of the shoulder 18. Moreover, the face of the seat member 21 which is presented to the end of the core 13 is shaped to provide an annular seating 23 about the end of the orifice 22. Located within the annulus 19 between the member 21 and the end of the core 13 is a valve plate 24 formed from magnetisable material.The valve plate is in the form of a disc slidably received within the annulus 19 and having extending therethrough a plurality of apertures 25 which are arranged in a circular row about the central axis of the plate. The mean diameter of the circular row of apertures 25 is greater than the diameter of the seating 23 and a compression spring 26 housed within the passage 14, urges the valve plate 24 into engagement with the seating 23. This is the closed position of the injector since engagement of the valve plate 24 with the seating 23 prevents flow of fuel between the inlet 12 and the outlet 15. The end of the spring 24 is located within a recess formed in the valve plate.

The internal diameter of the shoulder 18 is less than the diameter of the annulus 19 and the shoulder therefore overlies the outer peripheral region of the valve plate 24. When therefore the winding is energised the valve plate is attracted towards the flange and the end of the core 13. The thickness of the valve plate 24 is less than the thickness of the annulus 19 by a predetermined amount to permit the valve plate 24 to move by said predetermined amount. The movement of the valve plate is arrested by the shoulder and when in this position, fuel can flow through the passage in the port 13, across the upper face of the valve plate 24, through the apertures 25 therein, beneath the valve plate 24, over the top of the seating 23 and through the outlet orifice 22 into the outlet 15.

When the solenoid winding 17 is de-energised the spring 26 returns the valve plate 24 to its closed position in engagement with the seating 23.

In order to minimise the risk of the valve plate 24 tilting as it closes onto the seating 23 a further annular rib 28 is provided on the valve seat member 21. The rib 28 is disposed outwardly of the annular seating.

In order to ensure that the valve plate 24 returns quickly to its closed position when the solenoid is de-energised, a non-magnetic spacer 27 is placed between the shoulder 18 and the valve plate 24.

The spacer 27 thus prevents contact between the valve plate 24 and the shoulder 18 and thus improves the "drop off" characteristic of the valve.

The outlet orifice shown in Figure 1 includes an entrance portion of truncated conical form and an exit portion of right cylindrical form and the spray pattern produced by the orifice will be of pencillike form that is to say it will be more in the form of a jet of fuel.

In order to break up the jet of fuel leaving the orifice 22 there is mounted at the end of the outlet sleeve remote from the orifice a centrally disposed target upon which the jet of fuel impinges. The impingement of the jet of fuel upon the target causes the jet of fuel to be atomized to produce a spray of low penetrative power which however can mix very readily with the air flowing through the inlet manifold of the associated engine.

The target can have a number of forms two of which are seen in Figures 3 and 4. In Figure 3, the target 29 is in the form of a body of conical form having its apex directed towards the outlet orifice.

The conical body is supported in the outlet by cross-elements in the form of wires 30 of circular section.

In Figure 4 the target is defined by the junction of a pair of cross-elements in the form of wires 32 which extend across the outlet substantially at right angles to each other. Each wire is of triangular section with an apex directed towards the outlet orifice. The wires merge into each other the junction forming the target.

The target may be positioned nearer to the outlet orifice 22 or it can be mounted at a position exterior of the outlet 15.

The outlet 15 as described is formed from metal and is welded to the body 11. It may however be formed from plastics or other synthetic resin material with the targets 29, 30 and the supporting components moulded integrally therewith. In this case the outlet could be provided with a peripheral groove and the narrower end of the body 11 rolled into the groove to secure the outlet within the body.

Claims

1. A fuel injector comprising an injector body, a fuel inlet in the body, means defining a fuel outlet orifice, valve means for controlling fuel flow through the outlet orifice, said orifice producing when fuel flows therethrough, a jet of fuel, a solenoid device for controlling the operation of the valve means, and a target member disposed downstream of the orifice and upon which the jet of fuel leaving the orifice impinges, said target acting to break up the jet of fuel.

2. An injector according to Claim 1 including a sleeve retained within the body, said sleeve defining an outlet through which the jet of fuel passes, said target being supported by said sleeve.

3. An injector according to Claim 2 in which said target is supported in said sleeve by cross-elements.

4. An injector according to Claim 3 in which said target comprises a conical body and said cross-elements are in the form of wires of circular section.

5. An injector according to Claim 2 in which said target is defined by the junction of a pair of cross elements which extend across the outlet substantially at right angles to each other.

6. An injector according to Claim 5 in which said cross-elements are of triangular section with an apex directed towards the outlet orifice.

7. An injector according to Claim 3 in which said sleeve and said target are moulded integrally from synthetic resin material.

8. A fuel injector comprising the combination and arrangment of parts substantially as hereinbefore described with reference to the accompanying drawings.