GB2128252A

GB2128252A - Fuel injection nozzle

Info

Publication number: GB2128252A
Application number: GB08325092A
Authority: GB
Inventors: Robert Thomas John Skinner
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1982-10-14
Filing date: 1983-09-20
Publication date: 1984-04-26
Also published as: GB8325092D0

Abstract

The extension 19 of the valve member 17 has two grooves 20, 21 which define a land which obturates 3 outlets 16 until the valve member moves from its seat 14. An outlet (23 Fig. 2) at the seat 14 or an outlet (24, Fig. 3) in the extension 19 may provide discharge before the outlets 16 are progressively uncovered. <IMAGE>

Description

SPECIFICATION Fuel injection nozzle This invention relates to fuel injection nozzles of the so-called inwardly opening type and comprising a nozzle body in which is defined a cylindrical bore, a seating defined in the bore, a valve member shaped for co-operation with the seating, resilient means acting on the valve member to urge the valve member into contact with the seating, said valve member, in use, being lifted from said seating to allow fuel flow through outlet means disposed downstream of the seating, from a fuel inlet.

It is known with the aforesaid form of nozzle to provide the valve member with a "pintle" which essentially comprises a projection formed on the valve member and which extends with clearance through an outlet opening through which fuel flows when the valve member is lifted from the seating. The effect of the pintle is to provide a variable area through which the fuel flows and it can also provide some shaping of the resulting fuel spray. Some forms of engine combustion chamber require the spray to be directed away from the longitudinal axis of the valve member, this usually corresponding to the longitudinal axis of the nozzle. This is to allow the correct positioning of the nozzle in the wall of the combustion chamber.

It has proved difficult to design a pintle type of nozzle which can achieve the required direction while at the same time retaining the spray characteristics.

The object of the 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 outlet means comprises a right cylindrical aperture extending to the exterior of the nozzle body from downstream of the seating, a complementary extension formed on said valve member and slidable in said aperture, an outlet orifice extending from the wall of said aperture to the exterior of the body, first and second axially spaced grooves formed in said extension, said grooves defining a land which obturates said orifice in the closed position of the valve member, a passage in the extension interconnecting said grooves, the groove nearer to the valve member receiving fuel from the inlet when the valve member is lifted from the seating and the outlet orifice being progressively uncovered to the other groove as the valve member moves away from the seating.

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 showing part of a nozzle; Figures 2 and 3 are views similar to Figure 1 showing modifications; and Figure 4 is a side elevation showing a complete nozzle of the "pencil" type.

Referring to Figure 1 the fuel injection nozzle, only part of which is shown, includes a nozzle body 10 of stepped form and having defined therein a bore 11. Surrounding the bore intermediate its ends, is an enlargement 12 which constitutes a fuel supply gallery and to which fuel under pressure can be supplied by means of a passage 13. In use, the passage 13 is connected to the or an outlet of a high pressure fuel injection pump. At one end of the bore there is defined a seating 1 4 and downstream of the seating there is formed a right cylindrical aperture 1 5 which extends to the exterior of the nozzle body. This end of the nozzle body, in use, is exposed within the combustion chamber of the associated engine.

Moreover, extending from the wall of the aperture to the exterior of the body is one or more outlet orifices 1 6 positioned to provide the desired spray pattern.

Slidable within the bore 11 is a valve member 1 7 which has a reduced portion extending in the portion of the bore between the enlargement 1 2 and the seating 14 so as to define an annular clearance with the wall of the bore through which fuel can flow. The valve member is shaped for co-operation with the seating 14 and as is well known in the art, a coiled compression spring shown diagrammatically at 18, is provided to urge the valve member into contact with the seating.

Formed integrally with the valve member is an extension 19. The extension is of cylindrical form and is provided with a pair of circumferential axially spaced grooves 20, 21. The groove 20 is adjacent the valve member and when the valve member is lifted from its seating, receives fuel from the passage 13 by way of the aforesaid annular clearance. Formed in the extension are passages 22 which interconnect the two grooves.

The land which is defined between the two grooves in the closed position of the valve member obturates the orifices 1 6 but as the valve member is lifted from the seating, the inner ends of the orifices 1 6 are progressively uncovered to the groove 21 so that fuel flow can occur through the orifices 1 6 to develop fuel sprays in the combustion chamber. The flow areas of the orifices are progressively increased as the valve member moves away from the seating.

In Figure 1 two orifices 1 6 are provided and it will be appreciated that they can be configured in any required manner so as to direct fuel to the appropriate part of the combustion chamber. In the example shown in Figure 2, only one orifice 1 6 is provided but a further orifice 23 is formed and which extends to the exterior of the nozzle from the seating 14. In this example therefore fuel will flow through the orifice 23 as soon as the valve member is lifted from its seating and the orifice 1 6 will receive fuel slightly later due to the overlap of the land of the extension. The inner end of the orifice 1 6 will however be progressively uncovered as the valve member moves away from the seating.

In the example shown in Figure 3 the orifice 23 is omitted and a single orifice 1 6 is provided. In this example, an orifice 24 is provided in the extension, the orifice being directed in the axial direction. With this example therefore as soon as the valve member is lifted from the seating fuel will flow through the orifice 24 but as continued movement of the valve member away from the seating takes place, the inner end of the orifice 1 6 will be progressively uncovered.

The nozzles shown in Figures 1,2 and 3 are of the inwardly opening type and incorporate a comparatively short valve member. Figure 4 shows an injection nozzle of the so-called "pencil" type in which the valve member which is referenced 25, is much longer. This form of nozzle is used in engines where it is difficult to accommodate the form of nozzle shown in Figure 1. The valve member 25 is again of the inwardly opening type and is provided with the same form of extension as the valve member of Figure 1. The arrangement and disposition of the orifices can be as described with reference to the earlier Figures.In this example however the valve member is biased to the closed position by the compression spring 1 8 but after a predetermined movement of the valve member against the action of the spring 1 8, a further spring 26 is brought into operation, so that further movement of the valve member away from its seating requires that a higher fuel pressure should be supplied to the inlet 27 of the nozzle. In the particular example the abutment 28 for the spring 1 8 has a pair of lateral extensions 29 which engage with an abutment 30 for the spring 26, the extensions 29 being located in slots formed in the abutment 30. The total lift of the valve member in the arrangement shown in Figure 4 is represented by the dimension H2 while the movement of the valve member against the action of the spring 1 8 only is represented by the dimension H1. When the valve member has moved through the distance H1 it can be arranged that the orifices 1 6 are only partly uncovered to the groove 21 so that a substantial increase in the pressure of fuel supplied to the nozzle is required to completely uncover the orifices 1 6. It will be understood that the nozzles shown in Figures 1-3 can be modified in a similar manner.

Claims

1. A fuel injection nozzle of the so-called inwardly opening type comprising a nozzle body in which is defined a cylindrical bore, a seating defined in the bore, a valve member shaped for co-operation with the seating, resilient means acting on the valve member to urge the valve member into contact with the seating, said valve member, in use, being lifted from said seating to allow fuel flow through outlet means disposed downstream of the seating, from a fuel inlet, said outlet means comprising a right cylindrical aperture extending to the exterior of the nozzle body from downstream of the seating, a complementary extension formed on said valve member and slideable in said aperture, an outlet orifice extending from the wall of said aperture to the exterior of the body, first and second axially spaced grooves formed in said extension, said grooves defining a land which obturates said orifice in the closed position of the valve member, a passage in the extension interconnecting said grooves, the groove nearer to the valve member receiving fuel from the inlet when the valve member is lifted from the seating and the outlet orifice being progressively uncovered to the other groove as the valve member moves away from the seating.

2. A nozzle according to Claim 1 including a further outlet orifice, said further outlet orifice receiving fuel from said inlet as soon as the valve member is lifted from its seating.

3. A nozzle according to Claim 2 in which said further outlet orifice is formed in the nozzle body and extends to the exterior of the nozzle body from said seating.

4. A nozzle according to Claim 2 in which said further outlet orifice is formed in the exterior, said orifice communicating with the groove nearer to the valve member.

5. A nozzle according to any one of the preceding claims in which said resilient means comprises a first coiled compression spring operatively connected to the valve member and a second coiled compression spring which opposes movement of the valve member away from the seating after a predetermined movement of the valve member.

6. A fuel injection nozzle of the so-called inwardly opening type comprising the combination and arrangement of parts substantially as hereinbefore described with reference to the accompanying drawings.