GB2147950A

GB2147950A - Fuel injection nozzle for an I.C. engine

Info

Publication number: GB2147950A
Application number: GB08424373A
Authority: GB
Inventors: David Michael Harvey; Roger Cedric Lloyd
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1983-10-15
Filing date: 1984-09-27
Publication date: 1985-05-22
Also published as: GB8327685D0; GB8424373D0; GB2147950B

Abstract

A fuel injection nozzle includes a nozzle body 10 secured to one end of a tubular holder 21 by a cap nut 22. The other end of the bolder 21 is closed by an end closure member 23 having a tubular portion 24 projecting towards the nozzle body. The body 10 has a bore 11 in which is slidable a flanged valve member 14 having an integral tubular portion 17 slidable within the tubular portion 24. The portions 24, 17 convey fuel from an inlet 25 to a space 20 where the fuel pressure can act on the valve member to lift it from a seating 12 to allow fuel flow through an outlet 13. The valve member 14 is moved against the action of a spring 27 located between the flange 16 and the end closure member 23. <IMAGE>

Description

SPECIFICATION Fuel injection nozzles This invention relates to fuel injection nozzles for internal combustion engines and the object of the invention is to provide a nozzle of this type in a simple and convenient form.

According to the invention a fuel injection nozzle comprises a nozzle body, a valve member slidable within a bore in the body, a tubular holder, a cap nut securing said nozzle body to one end of the holder, an end closure member screw-threadedly engaged within the other end of the holder, said end closure defining a tubular portion extending towards said valve member and said valve member defining an integral flange and a further tubular portion, one of said tubular portions being slidably located about the other, said tubular portions providing a connection between a fuel inlet on the closure member and a passage in the valve member, a coiled compression spring disposed between said flange and said closure member and an area defined on said valve member against which fuel under pressure in said passage can act to lift the valve member against the action of the spring to allow fuel flow through an outlet.

According to a further feature of the invention said holder defines a step on its internal surface for engagement by said flange to limit the extent of movement of said valve member.

An example of a fuel injection nozzle in accordance with the invention will now be described with reference to the accompanying drawing which is a sectional side elevation of the nozzle.

Referring to the drawing the nozzle comprises a nozzle body 10 which is of stepped form and within which there is defined a bore 11. The bore extends between the wider end of the body and terminates adjacent the end of the narrower end of the body, in a seating 12, the seating surrounding an outlet orifice indicated at 1 3. Slidable within the bore 11 is a valve member 1 4 which is shaped for cooperation with said seating and which has a projection 1 5 which extends through the outlet 1 3. The valve member is also provided with an integral flange 1 6 and a tubular portion 17.Within the tubular portion and the main portion of the valve member is a fuel supply passage 1 8 which extends to adjacent the shaped end of the valve member and communicates with a pair of passages 1 9 with an annular space 20 which is defined by the valve member and the bore.

The nozzle also includes a tubular holder 21 and the nozzle body is secured to the holder by means of a cap nut 22, the holder and cap nut being provided with complementary screw threads. The end surface of the holder is held in sealing engagement with the body 1 0.

Mounted in screw thread engagement in the end of the holder remote from the nozzle body, is an end closure member 23. The closure member is also provided with a tubular portion 24 within which is slidably located the tubular portion 1 7. The end closure defines a fuel inlet 25 which in use, is connected to a high pressure fuel supply pump 26 and the two portions form a fuel connection between the inlet 25 and the passage 18. The valve member is biased to the closed position by means of a coiled compression spring 27 which is positioned between the end closure member 23 and the flange 1 6.

The chamber defined by the holder, the end closure and the nozzle body is vented to a drain by way of a vent passage 28 formed in the holder and in use, when fuel under pressure is supplied by the pump 26, the fuel under pressure is delivered to the space 20 and acts upon the area of the valve member which in part defines said space, to produce a force acting on the valve member which lifts the valve member against the action of the spring 27. As soon as the valve member is lifted from the seating, fuel can flow from the space 20 through the outlet 13, the flow area of the outlet being controlled by the projection 1 5. It is important to note that the fuel under pressure acts upon the end of the tubular portion 1 7 in a direction to close the valve member onto its seating.The area of the valve member exposed to the space 20 must therefore be larger than the end area of the portion 1 7.

In order to adjust the operating characteristics of the nozzle, it is necessary to be able to adjust the force exerted by the spring 27.

In most forms of fuel injection nozzle this adjustment has to be effected by means of shims but in the nozzle forming the subject of the present application, the force exerted by the spring can be adjusted simply by screwing the closure member 23 into or out of the holder. Once the adjustment has been effected, a locking ring 29 can be tightened to secure the parts together.

The extent of movement of the valve member against the action of the spring 27 is controlled in the present example, by the abutment of the flange 1 6 with a step 30 which is defined on the internal surface of the holder. The step 30 affords a stop surface of substantial area for the purpose of halting the movement of the valve member. Also shown in the drawing is a leak-off connector communicating with said passage 28. The connector comprises a hollow body 31 upon which is mounted a nipple 32. The body 31 is located about the holder 21 in spaced relation- ship so that fuel leaving the passage 28 can flow to the drain by way of a pipe connected to the nipple. A pair of spaced sealing rings 33, 34 are provided to prevent leakage of fuel over the body and the connector is retained in poisition by means of a securing nut 35 which is carried by the holder. The ring 33 is located within a groove formed in the holder 21 and the ring 34 is engaged by the end of the body 31 adjacent the cap nut 22, the end of the cap nut being shaped to provide location for the ring.

Claims

1. A fuel injection nozzle for an internal combustion engine comprising a nozzle body, a valve member slidable within a bore in the body, a tubular holder, a cap nut securing said nozzle body to one end of the holder, an end closure member screw-threadedly engaged within the other end of the holder, said end closure defining a tubular portion extending towards said valve member and said valve member defining an integral flange and a further tubular portion, one of said tubular portions being slidably located about the other, said tubular portions providing a connection between a fuel inlet on the closure member and a passage in the valve member, a coiled compression spring disposed between said flange and said closure member and an area defined on said valve member against which fuel under pressure in said passage can act to lift the valve member against the action of the spring to allow fuel flow through an outlet.

2. A nozzle according to Claim 1 in which said holder defines a step on its internal surface for engagement by said flange to limit the extent of movement of said valve member.

3. A nozzle according to Claim 1 in which the tubular portion defined by the valve member is slidable within the tubular portion defined by the end closure.

4. A nozzle according to Claim 1 in which said end closure is adjustably located in said tubular holder whereby the force exerted by the spring on the valve member can be adjusted, the nozzle including a locking ring to secure the holder and end closure against movement when the adjustment has been effected.

5. A nozzle according to Claim 1 including a vent passage formed in the wall of the holder, said passage opening into a chamber defined by the holder, the end closure and the nozzle body passage acting to vent the chamber, and a leak off connector communicating with said vent passage.

6. A nozzle according to Claim 5 in which said leak off connector comprises a hollow body surrounding the holder in spaced relationship, spaced seal means disposed between the hollow body and holder on opposite sides of the point of exit of said vent passage and a nipple on the hollow body for connection in use to a drain.

7. A fuel injection nozzle for an internal combustion engine comprising the combination and arrangement of parts substantially as hereinbefore described with reference to the accompanying drawing.