GB2113303A

GB2113303A - I.C. Engine fuel injection nozzle

Info

Publication number: GB2113303A
Application number: GB08300693A
Authority: GB
Inventors: George Kyriazis
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1982-01-23
Filing date: 1983-01-12
Publication date: 1983-08-03
Also published as: GB8300693D0

Abstract

An outwardly opening valve head 15 is located in an opening 12 in a valve body 10 and the head and the wall of the opening define right cylindrical portions which have a clearance such that no fuel flows therethrough when the head is lifted from the seating 13. The valve head defines flow paths 24 which each include a passage 26 having an exit 25 on the right cylindrical portion 21 of the head, the exit of the flow path being obturated by the wall of the bore in the seated position of the head and being progressively uncovered as the head moves away from the seating. The flow paths and seatings may have various forms, Fig. 5 to 7 (not shown). <IMAGE>

Description

SPECIFICATION Fuel injection nozzle This invention relates to a fuel injection nozzle for supplying fuel to an internal combustion engine, the nozzle being of the so-called outwardly opening type and including a body defining an opening, a valve head located in the opening, the valve head being resiliently biased into contact with a seating to prevent flow of fuel through an outlet and the valve head being lifted from the seating by the action of fuel under pressure supplied to an inlet of the nozzle thereby to allow fuel to flow through the outlet.

In a known form of such a nozzle the valve head and the wall of the opening define an annular clearance which defines the outlet and through which the fuel flows when the head is lifted from the seating. The resulting fuel spray is of generally conical form. Some engines function in a more satisfactory manner if the fuel spray has the form of one or more jets which produce a concentrated and more penetrative spray. This form of fuel spray can be obtained using what is known in the art as an inwardly opening injection nozzle but this form of nozzle is more expensive to produce and tends to be more bulk so that the problems of locating the nozzle on an engine are more severe.

It is an object of the present invention to provide a fuel injection nozzle of the kind specified in a form in which a fuel jet or jets of concentrated form can be obtained.

According to the invention in a fuel injection nozzle of the kind specified the valve head defines a flow path having an exit which is obturated by the wall of the opening in the closed position of the valve head, the exit being progressively exposed beyond the wall of the opening as the valve head is lifted from the seating, the clearance between the valve head and the wall of the opening being such that substantially all the fuel flow takes place along the flow path.

Examples of fuel injection nozzles in accordance with the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a sectional side elevation of a known form of outwardly opening nozzle, Figure 2 is a view to an enlarged scale of part of the nozzle seen in Figure 1 showing the modification in accordance with the invention, Figures 3 and 4 show the same form of nozzle as seen in Figure 2, with the valve member being in different positions, Figure 5 shows an alternative form of the nozzle to that which is shown in Figure 2, and Figures 6 and 7 show further modifications.

Referring to Figure 1 of the drawings the fuel injection nozzle comprises a body 10 in which is formed a bore 11. The bore 11 at the end of the body which in use opens into the combustion chamber of the engine is enlarged to define an opening 12 and the junction between the main portion of the bore and the opening 12 is of truncated conical form to define a seating 13.

Slidable within the bore is a valve member which includes a stem 14 and a head 15. The main portion of the stem 14 defines a clearance with the bore 11 but it is provided with a fluted guide portion 15A and a portion 1 6 which is slidable within the bore 11 and which extends beyond the end of the body. The portion 16 carries a spring abutment 1 7 between which and a flange on the body is located a coiled compression spring 18.

Moreover, the spring abutment is maintained against axial movement relative to the stem by means of a retainer member 19.

The body defines openings 20 through which fuel can flow into the annular clearance between the stem of the valve member and the wall of the bore 11 In practice the nozzle body is mounted within a casing which also defines a fuel inlet so that fuel under pressure can be admitted to the aforesaid clearance.

The head 1 5 of the valve member has a right cylindrical portion 21 and a first tapered portion 22 followed by a further tapered portion 23. The junction of the tapered portion 22 and 23 engages with the seating 13. In the example of Figure 1 which as mentioned is a known form of the nozzle an annular clearance exists between the wall of the opening 12 and the wall of the right cylindrical portion 21 and as a result, when the head is lifted from the seating by the action of fuel under pressure, fuel flows through the annular clearance to produce a generally conical spray.

Turning now to Figure 2, the clearance between the right cylindrical portion 21 of the valve head and the wall of the opening 12 is very much reduced so that substantially no fuel can flow along the working clearance. The valve head however is provided with in the particular example, two flow paths generally indicated at 24 and which are defined by passages formed in the valve head. The exits 25 of the flow paths are positioned such that they are obturated by the wall of the opening 12 in the closed position of the valve head. The exits are the ends of passages 26 drilled in the valve head and communicating with supply passages 27 which break out onto the surface of the tapered portion 22 of the valve head at a position adjacent the seating. In the example the axes of the passages 26 lie on the surface of an imaginary cone.In operation, when the fuel under pressure is supplied to the nozzle the valve head lifts and the exits 25 become exposed beyond the end of the nozzle body. As a resuit fuel can flow through the exits to provide in the particular example, two jets of fuel which form a spray pattern of increased penetrative power. In Figure 3 the valve head is shown in the fully open position and the clearance between the right cylindrical portion 21 and the wall of the opening 12 is such that substantially all the fuel flows through the aforesaid flow paths. In Figure 4 the valve member is shown in a partly open position and it will be seen that the exits 25 are only partially uncovered so that the orifices defined by the exits have a varying area as the valve member is moved.

In Figure 5 the flow paths 24 are formed by slots 28 which are formed in the valve head. Also as shown in Figure 5, the slots are inclined to the axis of the valve member. As in the previous examples the exits of the flow paths have a varying area as the valve head moves towards the open position.

In Figure 6 the valve head 1 5 is provided with an outwardly extending rim 29 which co-operates with a seating 30 defined on the end surface of the body. In the closed position as shown, the flow paths 24 are in open communication with the ports 20 and therefore with the inlet to the nozzle Again the clearance between the right cylindrical portion of the valve head and the wall of the opening 12 is such that in the open position of the valve member substantially all the fuel flows by way of the flow paths 24.

In the arrangement shown in Figure 7 each flow path 24 has a plurality of exits 31 formed by passages which are smaller in size than the passages 26. As before however each exit 31 is progressively uncovered as the valve member moves but it will be appreciated that the valve member must move a limited extent before the second of the drillings is uncovered.

The axes of the passages forming the adjacent exits 31 can converge so that when both exits are uncovered the resulting spray is a single spray.

Furthermore, if the valve member is restrained against angular movement the angles of the passages and slots relative to the axis of the valve member can be altered to give a particular spray pattern.

Claims

1. A fuel injection nozzle for supplying fuel to an internal combustion engine, the nozzle being of the so-called outwardly opening type and including a body defining an opening, a valve head located in the opening, the valve head being resiliently biased into contact with a seating to prevent flow of fuel through an outlet, the valve head being lifted from the seating by the action of fuel under pressure supplied to an inlet of the nozzle thereby to allow fuel to flow through the outlet, said outlet being defined by a flow path in the valve head, said flow path having an exit which is obturated by the wall of the opening in the closed position of the valve head, the exit being progressively exposed beyond the wall of the opening as the valve head is lifted from the seating, the clearance between the valve head and the wall of the opening being such that substantially all the fuel flow takes place along the flow path.

2. A nozzle according to Claim 1 in which said flow path is defined by a passage in the valve head having an exit on a right cylindrical portion of the valve head, said exit being obturated in the closed position of the valve head by a right cylindrical wall of the opening.

3. A nozzle according to Claim 2 in which said flow path has a plurality of exits.

4. A nozzle according to Claim 1 in which said flow path is defined by a groove in the valve head.

5. A nozzle according to Claim 1 in which said seating is disposed upstream of the flow path.

6. A nozzle according to Claim 1 in which said seating is disposed downstream of the flow path.

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

8. A fuel injection nozzle for supplying fuel to an internal combustion engine comprising the combination and arrangement of parts substantially as described with reference to Figure 1 as modified by Figure 5 of the accompanying drawings.

9. A fuel injection nozzle for supplying fuel to an internal combustion engine comprising the combination and arrangement of parts substantially as described with reference to Figure 1 as modified by Figure 6 of the accompanying drawings.

10. A fuel injection nozzle for supplying fuel to an internal combustion engine comprising the combination and arrangement of parts substantially as described with reference to Figure 1 as modified by Figure 7 of the accompanying drawings.