GB2054033A - I.C. engine fuel injection nozzle - Google Patents

Abstract

The nozzle includes a fuel pressure operable valve member 15 having a head 16 biassed into contact with a seating 14 by means of a tensioned wire 18. <IMAGE>

Description

SPECIFICATION Fuel injection nozzles This invention relates to a fuel injection nozzle of the kind intended to be used for supplying liquid fuel to a combustion chamber of an internal combustion engine and of the kind comprising a valve member slidable within a bore to which in use fuel under pressure is supplied, a seating defined about the bore adjacent one end thereof, a head on the outer end of said valve member for co-operation with said seating and resilient means for urging the head into contact with the seating, the arrangement being such that the head of the valve member will be urged in use away from the seating by the pressure of fuel within the bore to permit flow of fuel to the combustion space of the engine through an outlet defined by said one end of the bore.

In known forms of nozzles of the kind set out above coiled compression springs have been used to bias the valve head into contact with the seating. The spring together with the necessary spring abutment and the valve stem contribute substantially to the moving mass of the valve member thereby slowing the rate at which the valve head can move into contact with the seating. Other forms of nozzle have used coiled tension springs for biassing the head into contact with the seating but again a substantial part of the spring constitutes a moving mass which has the effect of slowing the movement of the valve member into contact with the seating. It is important that the valve head should move into contact with the seating as quickly as possible as the fuel pressure in the bore falls at the end of delivery of fuel, in order to minimise flow of improperly atomized fuel through the outlet.

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 resilient means comprises a tensioned wire one end of which is connected to the valve member, the other end of the wire being connected to a reaction member.

According to a further feature of the invention said reaction member is resiliently located and is movable to limit the tensile stress in the wire.

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 the first example; Figures 2 and 3 are views of a modification of the nozzle seen in Figure 1; and Figures 4, 5, and 6 show alternative constructions of nozzle.

Referring to Figure 1 of the drawings the nozzle comprises a movable body 10 of substantially cylindrical form and having a bore 11 extending therethrough. The body 10 is provided with a flange 12 whereby it can be secured in a holder.

Intermediate the ends of the bore 11, the body is provided with a pair of drillings 13 through whicn fuel can enter the bore from an inlet on the nozzle holder. The bore 11 at the end of the nozzle which in use will be located in the combustion chamber of the associated engine is slightly enlarged and defined between the two portions of the bore is an inclined portion which defines a seating 14.

Slidable within the bore is a fluted valve member generally indicated at 1 5 and which is provided with a head 1 6 which is shaped for co-operation with the seating 14. The head has an increasing diameter towards its outer end but it does define an annular space 17 through which as will be explained later, fuel can flow.

Located within the bore 11 is a tension wire 1 8 and this extends at one end through a drilling formed in the valve member 1 5 with the end of the wire being welded or otherwise secured to the valve member. As shown the drilling has a flared opening to facilitate the operation of securing the wire to the valve member. The connection between the wire and the valve member is of course fuel tight.

At its other end the wire is connected to a reaction member and the wire extends through a drilling in a ball 19 which is similarly provided with a conical recess. The wire is welded or otherwise secured to the ball 1 9. The ball itself is located within a conical recess formed within a first abutment member 20 which bears against a second abutment member 21. Formed in the end of the body 10 is a recess to accommodate the second abutment member 21 and located in the recess which is referenced 22, is a shim or shims.

The shims enable the initial tension in the wire to be adjusted and in order to permit such adjustment to take place the second abutment member 21 is provided with a slot in its periphery to permit the second abutment member to be located in position after the shims have been inserted.

In operation the pressure of fuel in the bore 11 acts against the head of the valve member to urge same in an outward direction against the restraining action of the wire 1 8. When the force exerted by the wire is overcome the valve head moves away from the seating to permit flow of fuel through the space 17. During the flow of fuel through this space it is atomised. At the end of the delivery of fuel the resilience of the wire moves the head back into contact with the seating and since the wire has a low effective moving mass and the valve member no stem, the movement of the valve member into contact with the seating is rapid.

An alternative way of adjusting the initial force exerted by the wire is shown in Figures 2 and 3. In this arrangement the ball 1 9 and the first abutment 20 are replaced by a truncated conical member 23 and an abutment 24 of annular form having a slot 24A. The abutment 24 is provided with a recess complementary to the shape of the member 23 and as seen in Figure 3, it is provided with an adjusting member in the form of a screw 25. When the screw 25 is tightened the size of the slot 24A will decrease and the member 23 will be urged upwardly and in so doing will increase the force exerted by the wire 1 8 on the valve member.

It is intended that shims should be provided in order to obtain coarse adjustment of the tension.

Occasions may arise when the pressure applied to the valve head becomes extremely high such as might cause the wire to be stretched beyond its elastic limit. This would be detrimental to the nozzle.

In order to minimise the risk of the wire being stretched beyond its elastic limit, the end of the wire remote from the valve head can be mounted in a spring loaded reaction member. In the example shown in Figure 4 the reaction member which is generally indicated at 26 comprises a plate 27 constituting an abutment for a coiled compression spring 28 located between the abutment and the body 10 of the nozzle. In this case the body 10 is considerably shorter than in the previous examples and the spring 28 together with the abutment and the wire 1 8 extend into a chamber defined in the nozzle holder and to which fuel is supplied in use, under pressure. The spring 28 is appreciably stiffer than the wire 1 8 so that in normal operation the valve member 1 5 is biassed by the resilience of the wire 18.In the event however that the fuel pressure acting on the valve member exceeds a predetermined value so that the valve member 1 5 is forced further away from the seating, the spring 28 will yield and will thereby prevent the stress in the wire 1 8 rising to a level such as would stretch the wire beyond its elastic limit. In the example shown in Figure 5 the reaction member 26 is of cup shaped form and whilst it still forms an abutment for the spring 28, it is also slidably mounted in a bore in the nozzle holder. The operation is the same as the arrangement shown in Figure 4.

In the arrangement shown in Figure 6 the construction of the reaction member 26 is the same as shown in Figure 4. In this case however in the closed position of the valve the abutment 27 is held in contact with a step in the bore in which it is located, by means of the compression spring 28.

In the examples shown in Figures 4 and 5 the force required to move the head of the valve member away from the seating is determined by the force acting in the spring and also in the wire.

In the arrangement shown in Figure 6 the aforesaid force is due to the force exerted by the wire 1 8 oniy and in the example of Figure 6 shims may be provided between the body 10 and the adjacent face of the holder 29, always assuming of course that the abutment 27 is maintained in contact with the step by the spring 28. As an alternative the nut 30 which retains the two parts together may engage with the body 29 at a position removed from the end and the extent of tightening of the nut will determine due to deformation of the body 29, the force exerted by the wire 1 8. The shims may however still be provided between the end of the body 29 and the body 10 to provide a coarse adjustment of the force in the wire 18.

Claims (4)

1. A fuel injection nozzle of the kind intended to be used for supplying liquid fuel to a combustion chamber of an internal combustion engine and comprising a valve member slidable within a bore to which in use fuel under pressure is supplied, a seating defined about said bore adjacent one end thereof, a head on the outer end of said valve member for co-operation with said seating and resilient means for urging the head into contact with the seating, the valve members in use being urged away from the seating by the fuel pressure in the bore to permit fuel flow through an outlet defined by the open end of the bore, characterised in that said resilient means comprises a tensioned wire one end of which is connected to the valve member and the other end of which is connected to a reaction member.

2. A nozzle according to claim 1 in which the bore is defined in a body, the reaction member being located at the other end of the bore.

3. A nozzle according to claim 2 in which the reaction member comprises first and second abutment members in face to face engagement, apertures in the abutment members through which the wire extends, said first abutment member defining a recess, and an element located in said recess said element being secured to the wire.

4. A nozzle according to claim 3 in which said element comprises a ball and said recess is of conical form.

4. A nozzle according to claim 3 in which shims are located between the second abutment and the body.

5. A nozzle according to claim 4 in which said element comprises a ball.

6. A nozzle according to claim 4 in which said element comprises a truncated conical member, said recess being of complementary shape and the first abutment being of annular form and having a slot and means for adjusting the size of the slot.

7. A nozzle according to claim 1 including a coiled compression spring which can deform to limit the stress in the tensioned wire.

8. A nozzle according to claim 7 in which said spring engages said reaction member to resist movement of the reaction member due to the force exerted by said tensioned wire.

9. A nozzle according to claim 8 in which said spring retains said reaction member in engagement with an abutment until the force exerted by the tensioned wire overcomes the force exerted by said spring.

10. A nozzle according to claim 1 in which said wire extends through a bore in the valve member, the wire being secured as by welding, to the valve member.

11. A fuel injection nozzle for supplying liquid fuel to a combustion chamber of an internal combustion engine comprising the combination and arrangement of parts substantially as hereinbefore described.

New claims or amendments to claims filed on 3Nov.1980.

Superseded claims 1 and 4 to 7.

New or amended claims Original claims 8 to 11 renumbered as 5 to 8 respectively and appendancies corrected.

1. A fuel injection nozzle of the kind intended to be used for supplying liquid fuel to a combustion chamber of an internal combustion engine and comprising a valve member slidable within a bore to which in use fuel under pressure is supplied, a seating defined about said bore adjacent one end thereof, a head on the outer end of said valve member for co-operation with said seating and resilient means for urging the head into contact with the seating, the valve member in use being urged away from the seating by the fuel pressure in the bore to permit fuel flow through an outlet defined by the open end of the bore, characterised in that said resilient means comprises a tensioned wire one end of which is connected to the valve member and the other end of which is connected to a reaction member, the nozzle including a coiled compression spring which can deform to limit the stress in the tensioned wire.