GB2260165A

GB2260165A - I.c. engine fuel injector

Info

Publication number: GB2260165A
Application number: GB9120873A
Authority: GB
Inventors: David John Gaskell; Stephen John Prosser
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1991-10-01
Filing date: 1991-10-01
Publication date: 1993-04-07
Also published as: GB9120873D0

Abstract

The opening movement of the fuel pressure operated valve member produces a pressure rise in a space 26 which is in part defined by the valve member. A transducer 25 is provided which is responsive to the pressure in the space and this provides a signal upon opening movement of the valve member, the signal being utilised in an engine control system. <IMAGE>

Description

FUEL INJECTION NOZZLE This invention relates to fuel injection nozzles for supplying fuel to internal combustion engines, the nozzles being of the type having a valve member slidable in a bore formed in a nozzle body, a seating at one end of the bore, the valve member being shaped for cooperation with the seating to prevent flow of fuel through an outlet, resilient means biasing the valve member into engagement with the seating, said resilient means being housed in a chamber formed in a holder having an end wall against which the nozzle body is located, said valve member being movable away from said seating to permit fuel flow through said outlet, an opening formed in said end wall and through which a reduced extension on the other end of the valve member projects, and means engaging said extension and interposed between the extension and said resilient means and through which the force developed by said resilient means is transmitted to the valve member.

Such nozzles are well known in the art being commonly known as "inwardly opening" nozzles. In order to satisfy emission laws now enacted or in the process of being enacted, in many countries of the world and in order to economise so far as is possible, on the consumption of fuel it is necessary to be able to control the instant of fuel delivery to the engine. For accurate control it is necessary to know when the valve member lifts from its seating. Various nozzles are known which incorporate means responsive to the movement of the valve member to provide the desired signal. One such example is disclosed in GB-A-2153429. In this example a plunger forming part of an electrical switch, is spring biased in one direction and is urged in the opposite direction against the action of the spring, by fuel displacement from said chamber when the valve member is lifted from its seating.In this example, the means which engages the extension is constructed so as to form with the wall of said chamber, a piston which displaces fuel from a portion of the chamber as the valve member is moved away from its seating. The pressure generated acts upon the plunger to move same against the action of its spring.

The movement of the valve member is very small and although the piston is of larger diameter, the actual displacement of fuel from the chamber is comparatively small moreover, the increase in pressure is also comparatively small since the chamber is connected to a low pressure source which receives fuel leaking along the working clearance defined between the valve member and the wall of the bore.

The object of the present invention is to provide a fuel injection nozzle of the kind specified in an improved form.

According to the invention a fuel injection nozzle of the kind specified comprises a pressure transducer responsive to the pressure developed on opening the valve member, in the portion of the other end of the bore defined between said end wall and the other end of the valve member.

According to a further feature of the invention said pressure transducer is mounted in a recess formed in one surface of an adaptor plate which forms said end wall of the holder.

According to a still further feature of the invention another surface of the adaptor plate carries one part of an electrical connector which is electrically connected to the transducer, the other part of the connector being mounted on a further part of the holder.

An example of a fuel injection nozzle in accordance with the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a side elevation of the nozzle with parts removed, and Figure 2 is a view to an enlarged scale of the part of the nozzle which is enclosed within the circle of Figure 1.

Referring to the drawings the fuel injection nozzle comprises a nozzle body 10 in which is formed a bore 11 at one end of which is defined a seating 12 surrounding an outlet 13. Adjacent the seating the bore is of enlarged form to define a recess which is connected to a supply passage 14 opening into an annular groove 15 formed in the end face of the body.

Slidable in the bore is a valve member 16 which at one end is shaped for cooperation with the seating 12 and which in the particular example, carries a pin which extends through the outlet 13. The valve member has a cylindrical extension 17 of reduced diameter.

The nozzle also includes a holder generally indicated at 19 and which comprises a distance piece 20 which is positioned between the nozzle body 10 and the main portion of the holder 21. The portion 21 of the holder defines a chamber 22 and extending through the distance piece 20 is a stepped opening 23. The nozzle also includes a spring abutment (not shown) which is mounted on the extension 17 and which locates one end of a coiled compression spring (not shown) which is accommodated within the chamber 22. The force exerted by the spring urges the valve member 16 into contact with the seating 12. The groove 15 communicates by way of passages not shown formed in the distance piece 20 and the part 21 of the holder, with a fuel inlet which in use is connected to an outlet of a fuel injection pump.When fuel is delivered by the pump the fuel under pressure acts upon the valve member to urge the valve member against the action of the spring and when the force produced by the fuel pressure is sufficient, the valve member 16 is lifted from its seating to allow flow of fuel through the outlet 13. When the supply of fuel by the injection pump ceases, the valve member is returned into engagement with the seating, by the action of the spring. The full extent of movement of the valve member is limited by the abutment of the annular end surface of the valve member about the extension 17, with the adjacent face 24 of the distance piece.

In order to provide an indication of movement of the valve member away from its seating, a pressure sensor 25 is provided and this is located within a recess which is set into the surface 24 of the distance piece. The position of the recess is such that its open end communicates with the annular space 26 which is defined between the end of the valve member and the adjacent face 24 of the distance piece. The volume of the space 26 diminishes as the valve member is moved away from the seating and the space communicates with the chamber by way of a limited clearance 27 defined between the side wall of the extension 17 and the wall of the narrower portion of the opening 23. The size of the clearance between the extension and the wall of the opening is such that upon movement of the valve member, a pressure rise will occur in the space 26 which will be sensed by the transducer 25.The size of the clearance is carefully chosen so as to ensure that there is an adequate clearance for fuel to leak into the chamber 22, the fuel having flowed along the working clearance defined between the valve member and the wall of the bore.

It is preferable to form the distance piece as a separate item from the remaining portion of the holder however, a one piece construction can be employed providing an opening into the end of the chamber remote from the valve member, is sufficiently large to enable the spring to be passed into the chamber. The transducer 25 is protected from excessive rises of pressure and from fuel by the provision of a masking plate 31. The injection nozzle in use is located within a bore formed in the cylinder head of the engine which means that a substantial portion of the holder 19 as well as the nozzle body, are inaccessible. It is of course necessary to make electrical connections to the transducer 25 and in order to achieve this, the recess 25 which is formed in the surface 24, communicates by way of a passage 28 with a further recess formed in the opposite surface of the distance piece and extending within the passage 28 is a lead or leads which are connected to one part 29 of an electrical connector the other part of which is located within a further recess formed in the part 21 of the holder. The further recess is connected to one end of a drilling through which extend electrical connections which terminate at terminals 30 on the end wall of the part 21 of the holder.

Since it is necessary to maintain the correct relationship between the distance piece 20 and the remaining portion of the holder, a spigot 31 is provided which assures the correct relationship when a cap nut not shown is tightened.

Claims

1. A fuel injection nozzle for supplying fuel to an internal combustion engine comprising a valve member slidable in a bore formed in a nozzle body, a seating at one end of the bore, the valve member being shaped for cooperation with the seating to prevent flow of fuel through an outlet, resilient means biasing the valve member into engagement with the seating, said resilient means being housed in a chamber formed in a holder having an end wall against which the nozzle body is located, said valve member being movable away from said seating to permit fuel flow through said outlet, an opening formed in said end wall and through which a reduced extension on the other end of the valve member projects, means engaging said extension and interposed between the extension and said resilient means and through which the force developed by said resilient means is transmitted to the valve member, and a pressure transducer responsive to the pressure developed on opening the valve member, in the portion of the other end of the bore defined between said end wall and the other end of the valve member.

2. A nozzle according to Claim 1, in which said pressure transducer is mounted in a recess formed in one surface of an adaptor plate which forms said end wall of the holder.

3. A nozzle according to Claim 2, in which another surface of the adaptor plate carries one part of an electrical connector which is electrically connected to the transducer, the other part of the connector being mounted on a further part of the holder.

4. A fuel injection nozzle comprising the combination and arrangement of parts substantially as hereinbefore described with reference to the accompanying drawings.