Background Art Known fuel injector designs include a valve needle, which is engageable with a valve needle seating to control fuel injection to the engine. The valve needle is biased towards the valve needle seating by means of a spring force acting in combination with a force due to fuel pressure within a pressure control chamber at a back end of the needle. Pressure within the control chamber, and hence valve needle movement, is controlled by means of a nozzle control valve to control injection timing.

The nozzle control valve has an associated actuator arrangement, typically in the form of an electromagnetic actuator arrangement, which is operable, in use, to control movement of the nozzle control valve between open and closed positions. Usually, a drive current is supplied to a solenoid of the actuator to energise the solenoid to open the nozzle control valve. Deenergisation of the solenoid causes the nozzle control valve to close.

The injector is mounted within an injector pocket formed within the engine cylinder head.

A connector arrangement is provided to supply the drive current to the nozzle control valve actuator, including conductors which pass through the injector body between an electrical connector mounted externally to the injector pocket, and a set of electrical

contacts in connection with the actuator arrangement. The electrical connector is subsequently connected to the engine harness and the engine control unit (ECU), to permit the necessary drive current to be supplied to the actuator arrangement to control injection timing.

It is necessary to ensure the components of the connector arrangement are insulated and adequately sealed from fuel. One problem with a connector arrangement of the aforementioned type is that there is relatively little space within the injector body to fit the seals and insulation and, thus, such arrangements tend to be complex, expensive and difficult to assemble. The problem is exacerbated in more sophisticated injector designs in which two solenoids are provided and additional conductors and connectors are required.

In unit injector designs, in which the injector has a pumping plunger mounted within a common housing with the injection nozzle, a further problem is encountered in that an additional drilling is required through that part of the common housing through which the pumping plunger extends to pass the conductors between the electrical contacts at the actuator end and the electrical connector at the supply end. The stiffness of the housing is therefore compromised, and additional fuel leakage may occur into the engine through the additional drilling.

It is an object of the present invention to provide an improved mounting arrangement for a fuel injector which overcomes or alleviates at least one of the aforementioned problems.

Summary of Invention According to a first aspect of the invention, there is provided an injector mounting arrangement including:

an engine cylinder head provided with an injector pocket, a fuel injector mounted within the injector pocket. including a nozzle control valve for controlling fuel pressure within a control chamber so as to control movement of an injector valve needle and an actuator arrangement for controlling movement of the nozzle control valve, and an electrical connector arrangement for supplying current to the actuator arrangement, wherein a part of the electrical connector arrangement is arranged to extend, at least in part, through a bore provided in the engine cylinder head to permit current to be supplied to the actuator arrangement, in use.

The engine cylinder head provides an increased accommodation space for the electrical contacts and conductors between the engine harness and the actuator arrangement, and thus the insulators and seals for the electrical connector arrangement need not be so compact and complex as those required for existing injector/connector designs.

In a preferred embodiment, the electrical connector arrangement includes: first electrical contact means for connection to the actuator arrangement, second electrical contact means for connection to the first electrical contact means, conducting means for supplying a drive current to the second electrical contact means, wherein said conducting means is arranged to extend though the engine cylinder head.

The electrical connector arrangement may also include an electrical connector for connection to an engine harness and/or an engine control unit (ECU).

In one embodiment, the first electrical contact means includes a first electrical contact, typically in the form of a pin, which extends radially from the injector body.

In an alternative embodiment, the first electrical contact means extends from the injector body substantially along the injector body axis.

The electrical conductor arrangement preferably includes a conductor housing mounted within the bore in the cylinder head. The conductor housing is preferably arranged to house conducting wires which terminate, at one end thereof, at the second electrical contact means.

Preferably, the actuator arrangement is an electromagnetic actuator arrangement including a winding for connection to the first electrical contact means, in use.

In one embodiment, the cylinder head is provided with a bore which extends substantially perpendicular to the axis of the injector body.

In an alternative embodiment, the cylinder head is provided with a bore which is oriented at a non-perpendicular angle to the axis of the injector body.

The first electrical contact means may include angled contact pads for connection with correspondingly angled contact pads of the second electrical contact means.

The provision of angled contact pads may benefit the procedure by which the mounting arrangement is assembled.

The fuel injector may take the form of a unit injector having an injection nozzle and an

associated pumping plunger mounted within a common housing.

According to a second aspect of the invention, there is provided a fuel injector forming part of the injector mounting arrangement of the present invention.

It will be appreciated that, in accordance with another aspect of the invention, the mounting arrangement may be manufactured without the injector.

In accordance with a further aspect of the invention, a method of assembling a mounting arrangement for an injector arrangement comprises: (i) inserting an injector body provided with first electrical contact means into a first bore provided in an engine cylinder head, and (ii) inserting a conducting arrangement provided with second electrical contact means into a second bore provided in an engine cylinder head, such that the first and second electrical contact means mate with one another.

Steps (i) and (ii) may be carried out in the sequence of step (i) followed by step (ii).

Alternatively, the reverse sequence may be preferred if the first electrical contact means include angled contact pads for connection with correspondingly angled contact pads of the second electrical contact means.

Brief Description of the Drawings The invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a schematic diagram of an injector mounting arrangement of the present invention including a connector arrangement for the nozzle control valve, and Figures 2 and 3 show alternative embodiments to that shown in Figure 1.

Detailed Description of Preferred Embodiments In a known fuel injector design, the fuel injector includes a valve needle which is movable towards and away from a valve needle seating to control fuel injection under the control of a nozzle control valve. The nozzle control valve is arranged to control fuel pressure within a control chamber, typically arranged at the back end of the needle, and is operable between an open position, in which the control chamber communicates with a low pressure drain, and a closed position in which communication between the control chamber and the drain is broken.

In order to provide an injection of fuel, the nozzle control valve is opened to permit fuel within the control chamber to escape to low pressure, thereby causing fuel pressure within the control chamber to be reduced. A point will be reached at which the force due to fuel pressure acting on thrust surfaces of the valve needle is sufficient to overcome the force due to fuel pressure within the control chamber (usually acting in combination with a spring force), and the valve needle lifts from its seating. Closure of the valve needle is effected by closing the nozzle control valve to re-establish high pressure fuel within the control chamber.

The nozzle control valve has an associated actuator arrangement, typically in the form of an electromagnetic actuator including a winding to which a current is supplied, in use, to energise the winding and thus to move the nozzle control valve into its open state. Upon removal of the current, the winding is deenergised and the nozzle control valve is caused

to close.

Figure 1 shows an injector mounting arrangement of the present invention in which the electrical connection means for supplying current between the engine harness (not shown) and the actuator arrangement of the injector nozzle control valve is shown. The arrangement includes an injector body 10, which is mounted within a first bore 12 provided in an engine cylinder head 14. A lower end of the injector body 10 (in the illustration shown) is secured to an injector nozzle body 16, within which the valve needle of the injector is received. The nozzle body 16 extends through an open end of the first bore 12 into an associated engine cylinder.

At the end of the injector body 10 remote from the nozzle body 16, the injector body 10 includes a first housing part 18 for a pumping plunger (not shown) or other pumping element. The plunger is driven, in use, to pressurise fuel within a pump chamber of the injector arrangement in a conventional manner. A seal 20, for example an O-ring seal, is mounted near the open, upper end of the first bore 12 to substantially seal the first bore 12 against fuel leakage.

The nozzle control valve (not shown) of the injector is housed within a further housing part 22 of the injector body 10 located intermediate the injector nozzle body 16 and the plunger housing part 18. A pair of first electrical contacts or contact pins 24 extends from the side wall of the housing part 22 of the injector body 10. The contact pins 24 extend radially from the injector body 10 along an axis substantially perpendicular to the axis 10a of the injector body 10, and are arranged to mate with corresponding electrical contacts (not shown) arranged at one end of a conductor arrangement 26. The conductor arrangement 26 includes a tubular conductor housing 27 through which conducting wires 25 extend to permit a supply of current between the engine harness and the electrical contacts 24 on the injector body 10. The conductor housing 26 is received within a second

bore 28 provided in the cylinder head 14. The second bore 28 is arranged such that it is substantially perpendicular to the axis 10a of the injector body 10 and the tubular conductor housing 26 therefore projects through the open end of the second bore 28 on one side of the cylinder head 14. A second O-ring seal 29 is located within the second bore 28 to provide a substantially fluid tight seal against fuel leakage through the second bore 28.

In order to assemble the mounting arrangement, the injector body 10 is first inserted into the first bore 12 of the cylinder head 14, and the appropriate seals (e. g. O-ring seal 20) are provided. The conductor housing 26 is subsequently inserted into the second bore 28, and the electrical contacts at the end of the conducting wires 25 are mated with the contact pins 24. An additional electrical connector (not shown) at the other end of the conducting wires 25 is connected with the engine harness/ECU and appropriate seals (e. g. O-ring seal 29) are provided to seal the second bore 28.

The sequence of assembly steps may be reversed if the electrical contacts 24 on the injector body 10 are provided with angled contact pads which mate with correspondingly angled contact pads at the end of the conductor arrangement 26. In this case, the conductor arrangement 26 may first be mounted within the second bore 28, prior to insertion of the injector housing 10 into the first bore 12.

As the conductor arrangement 26 projects through a side face of the cylinder head 14, there is no requirement for an axially extending electrical conducting path through the injector body 10. It is a disadvantage of known unit injector designs that an additional drilling is required through the injector body 10, adjacent to the plunger bore, for the passage of electrical conducing wires, which compromises the stiffness of that region of the injector body 10. The present invention has a particular advantage for twin-actuator injectors, for which additional electrical contacts and conducting wires are required.

It is a further advantage of the arrangement in Figure 1 that, should the seal 29 for the conductor arrangement 26 fail, there is no risk of the engine filling with fuel as it escapes through the side face of the cylinder head 14.

Referring to Figure 2, if the cylinder head 14 is of limited size, and there is insufficient space to accommodate a perpendicular second bore 28, the cylinder head 14 may instead be provided with a bore 30 having an axis 30a oriented at a non-perpendicular angle to the axis 10a of the injector body 10. An arrangement of angled electrical contacts on the injector body 10 and on the conductor arrangement 26 may be provided, as described previously in relation to Figure 1.

A further alternative embodiment is shown in Figure 3, in which a second bore 28 is again provided in the cylinder head 14 for the purpose of mounting an electrical conductor arrangement 26. In this embodiment, the electrical contact pins 24 (only one of which is visible) project from the injector body 10 in a direction substantially parallel to the axis 10a of the injector body 10.

It may be preferable to provide the cylinder head 14 and/or the conductor arrangement 26 with a guide means to correctly align the electrical contact pins as conductor arrangement 26 is inserted into the bores 28,30. For example, the outer surface of the conductor housing 27 may be provided with a formation or feature which cooperates with a correspondingly shaped formation in the second bore 28,30 to ensure the electrical contacts on the electrical conductor arrangement 26 mate correctly with the electrical contacts 24 on the injector body 10.

The electrical contacts 24 on the injector body 10, and those of the conductor arrangement, may be mounted within plastic mouldings which serve to provide both an

electrically insulating and a sealing function. The contacts of the conductor arrangement 26 may also be spring-loaded so as to allow for the effects of fatigue or creep in the plastic moulding and the effects of vibration of the cylinder head 14.

The contacts need not be provided in pairs, and it will be appreciated that a plurality of contacts may be required in some applications. Conveniently, the contacts may take the form of contact pins and/or pads, as described previously, or may be of the male/female type. Alternatively, the contacts may be of the jack plug/coaxial type, in which case they may be of the conical or tapered form. Such conical or tapered contacts may be particularly advantageous when the conductor arrangement is inserted into the bore in the cylinder head during assembly to engage the contacts with one another.