CN109154260B

CN109154260B - Fuel injector for combustion engine

Info

Publication number: CN109154260B
Application number: CN201780025572.7A
Authority: CN
Inventors: X·拉莱; B·班伯内; C·塔潘; J-L·贝多诺; L·多拉杜克斯
Original assignee: Delphi Technologies IP Ltd
Current assignee: Delphi Technologies IP Ltd
Priority date: 2016-02-26
Filing date: 2017-02-21
Publication date: 2020-12-01
Anticipated expiration: 2037-02-21
Also published as: WO2017144479A1; GB201603329D0; JP2019507281A; CN109154260A; EP3420217B1; EP3420217A1; GB2547684A

Abstract

A fuel injector has: a head adapted to provide a connection to and from the ECU for selectively energizing the actuator to start and stop fuel injection pulses; a fuel supply connection for supplying fuel at an elevated pressure into the injector; a fuel return connection for returning fuel at low pressure; a fuel injection nozzle having at least one nozzle opening disposed at one end of the valve guide; a valve member movable in a chamber defined within the valve guide and biased to close against a valve seat and inhibit fuel injection through a nozzle, and to move away from the valve seat within the valve chamber to inject fuel through the nozzle. A circuit is provided for detecting whether the nozzle is open or closed by an electrical change. The circuit comprises: a conductor extending between the heads of the fuel injector in an outer region of the body of the injector or through an isolation member for the actuator to a position generally at the head end of the actuator; a contact member located at the head end of the actuator and in electrical contact with the conductor; and a resilient electrical link extending between the contact member and one of the valve member and the valve guide.

Description

Fuel injector for combustion engine

Technical Field

The present invention relates to a fuel injector for a combustion engine.

Background

More specifically, the present invention relates to a fuel injector having: a head provided with an electrical connector adapted to provide a connection to and from the ECU for selectively energizing the actuator via the electrical connection to start and stop a fuel injection pulse; a fuel supply connection for supplying fuel at an elevated pressure into the injector; a fuel return connection for returning fuel at low pressure; a fuel injection nozzle assembly, the assembly having: a nozzle body having a nozzle opening at one end; a valve member axially guided in the nozzle body between an upper guide member and a lower guide, the valve member being adapted to be biased to close against a valve seat and inhibit fuel injection through a nozzle opening, or to move away from the valve seat to enable fuel injection through the nozzle opening; a fuel passage that communicates fuel from the supply connection to the nozzle opening; a branch from the fuel passage to a control chamber into which an end of the valve member remote from the valve seat projects so that fuel pressure in the chamber urges the valve member towards the valve seat when the nozzle is in a closed position; and a control valve operated by the actuator to allow fuel to pass from a control chamber to the return connection, thereby reducing pressure in the chamber and enabling the valve member to move away from the valve seat when the nozzle is in an open position, thereby enabling the fuel injection,

fuel injectors of this type are known per se, and the actuator may in fact be a solenoid-type actuator or a piezoelectric actuator. Regardless of the specific design of the actuator used, operation of the control valve directing fuel from the branch to the return connection reduces the operating pressure in the chamber and moves the valve member away from the valve seat in the nozzle-open position, thereby enabling the formation of a fuel injection pulse.

As soon as the control valve is closed by a signal sent from the ECU to the actuator, the pressure in the branch increases again, whereby the pressure operating on the end face of the valve member increases, pushing the valve member again towards the valve seat. As explained above, the valve member is normally biased towards the valve seat by a spring, such as a compression coil spring, so that the valve member always moves in the closing direction as soon as the rising fuel pressure from the branch acts on the end face of the valve member. Once the nozzle is closed by the valve member sealing against the valve seat, the net hydraulic pressure operating on the valve member is directed towards the valve seat. The reason for this is that the area of the valve member above the valve seat in the chamber, on which the fuel pressure acts, is smaller than the area of the end face of the valve member, on which the same pressure acts. The force resulting with the force of the biasing means is always sufficient to keep the valve member in contact with the valve seat against the force of the combustion pressure acting on the valve member on the combustion side of the valve seat by nozzle opening.

It is now known to obtain a major improvement in the control of the fuel injection devices and injection events by means of a so-called closed-loop control method which makes it possible to more accurately control the opening and closing of the fuel injectors and thus the fuel injection quantity in each injection pulse. In this method, which is performed by an Electronic Control Unit (ECU) that controls the operation of a control valve of a fuel injection device, in particular a fuel injector, the fuel injector is provided with a closed-loop arrangement that enables an electrical signal to be generated when the valve member reaches the closed position. In other embodiments, the signal may also assume a particular value when the valve member is in the fully open position. Such closure devices typically include electrically isolating the valve needle relative to the nozzle body, but electrically conducting the moving seating surface and the fixed seating surface to each other. In this way, the valve needle and the nozzle body cooperate as electrical switching components of an electrical circuit that is closed when the valve needle is in the closed position and open when the valve needle is in the firing mode or in the fully open position. As a result, a 0-1 step signal may be measured and may be input as a feedback signal into an Electronic Control Unit (ECU) controlling the fuel injection device, the feedback signal being taken into account in parameters of a control algorithm of the fuel injection device.

The following various embodiments of such a closure device have been disclosed in PCT/EP 2014/073662, FR1456783 and FR 1457078.

In our invention described in our previously unpublished UK application GB1541007.5, a nozzle assembly is provided in which the electrical circuit comprises a valve needle, a nozzle body, a spacer means which prevents electrical contact between the valve needle member and the nozzle body when the valve needle is in the firing mode between open and closed positions, so that an electrical signal which enables contact detection between the two seating surfaces can determine whether the valve member is in sealing contact with the valve seat. This allows for more accurate timing of the start and end of each fuel injection pulse.

Disclosure of Invention

The object underlying the present invention is to improve a fuel injector of the type mentioned at the outset in such a way that an advantageous arrangement is provided for the electrical path for the transmission of an electrical switching signal through the injector for detecting nozzle opening or closing by electrical change. According to the invention, a fuel injector of the type mentioned at the outset comprises a circuit for detecting the opening or closing of the nozzle by electrical change, said circuit extending between the electrical connector and the upper guide member, said circuit comprising a resilient electrical link.

A wide variety of designs are contemplated for the resilient electrical link of the present invention.

Thus, in one embodiment of the invention, the resilient electrical link conveniently comprises a rigid conductor member and at least one axially resilient conductor member arranged in series with the rigid conductor member. The axially resilient conductor member may comprise a spring contact member. This may take the form of a resilient element such as a coil spring or leaf spring, or may be formed by a solid contact pin resiliently supported on the rigid conductor member, for example a conductive rod or tube having a hollow end supporting a coil spring urging the contact pin outwardly. The resilient electrical link is provided with an insulator except at the free end of the contact pin.

This design ensures that a good electrical contact is always obtained regardless of manufacturing tolerances and avoids the need to provide a brazed or crimped connection.

In a particularly preferred embodiment, the elastic electrical link is formed by a helical spring. This is a relatively inexpensive implementation to implement.

The coil spring may have elasticity over its entire length, or may include: a first portion having a coil in contact, the first portion being axially inelastic; and a second portion, wherein the coils of the spring are separated from each other, the second portion having elasticity.

In another embodiment, the helical spring forming the resilient electrical link is further provided with a third portion, the spring coils of which are separated from each other, the third portion thereby having an axial resilience. In this design, the first portion is a central portion of the coil spring, the second portion is an end portion of the spring in contact with the upper guide member, and the third portion is an end portion of the spring in electrical contact with the contact member. The helical spring is conveniently provided with an insulator beyond its end which makes electrical contact with the contact member and the upper guide member.

In one embodiment, the circuit for detecting whether the nozzle is opened or closed by an electrical change further comprises: a conductor disposed along an electrical connection for the actuator at a location generally at a head end of the actuator: a contact member located at the head end of the actuator and in electrical contact with the conductor; and the resilient electrical link extending axially along the actuator from the contact member to the upper guide member.

This arrangement reflects the fact that: the alignment of the actuator relative to the body of the fuel injector, the angular position of the electrical link relative to the actuator, and the relative position of the conductor at the junction between the actuator isolation member and the actuator may vary during assembly of the fuel injector due to manufacturing tolerances. By using a contact member having a sufficient area range, electrical contact problems due to alignment tolerances can be avoided.

The conductor and the resilient electrical link are directed parallel to the longitudinal axis of the actuator, but do not necessarily coincide with each other, but may be radially offset relative to each other.

In a basic embodiment of the invention, the electrical connection for the actuator is conveniently electrically isolated by means of an isolating member extending through an axial bore provided in the injector body between the head and the actuator, and the insulated conductor of the circuit for detecting by electrical variation whether the nozzle is open or closed is conveniently arranged within the isolating member along the electrical connection to the actuator.

Thus, the connection between the actuator and the head may extend through an axial bore or one or more axially parallel bores in an isolation member for the actuator extending between the head and the actuator, and the conductor for detecting a closed circuit of the valve member may extend through the same bore or one of the axial bores, or through another axially directed bore of the isolation member. This enables a compact arrangement and facilitates the electrical connections to an ECU (engine control unit) located at the head of the injector.

In a basic alternative embodiment of the invention, the electrical connection for the actuator is electrically isolated by means of an isolating member extending through an axial bore provided in the injector body between the head and the actuator, and an insulated conductor of a circuit for detecting by electrical variation whether the nozzle is open or closed is arranged along the isolating member outside the isolating member.

In the embodiment of the invention described above, the end of the insulated conductor of the circuit for detecting whether the nozzle is open or closed by electrical change is bent at approximately right angles opposite to (i.e., away from) the head to contact the contact member.

The contact member is conveniently designed as a disc member arranged substantially on the head of the actuator, the disc having an upper or lower surface in electrical contact with the conductor and the lower surface being in electrical contact with the resilient electrical link. It is particularly advantageous for the assembly of a fuel injector and an electrical circuit for detecting whether the nozzle is open or closed by electrical variation.

The disc may conveniently be provided with a nose portion extending radially beyond the actuator, the resilient electrical link being in contact with a bottom surface of the nose portion.

The conductor of the circuit for detecting whether the nozzle is open or closed by electrical change can be conveniently welded or soldered to the disc.

The resilient electrical link ensures good contact with the contact member and a respective one of the valve member or valve guide despite thermal growth that may occur in use.

The contact member preferably comprises an axial disc substantially coaxial with the actuator and surrounding an axial spacer member for the actuator extending between the head and the actuator. The axial disk is capable of easily contacting the conductor and the electrical link over at least a range of angles suitable to account for misalignment of the end of the conductor and the electrical link.

In this arrangement, the contact member may be urged into contact with the end of the conductor at the head end of the actuator by a compression coil spring surrounding an isolation member for the actuator. This embodiment is compact, simple to assemble and relatively inexpensive to implement.

In one embodiment, the circuit for detecting by electrical variation whether the nozzle is open or closed extends in a straight direction parallel to and radially offset from the longitudinal axis of the injector, the circuit extending from the head of the injector to the upper guide member.

The present invention may be used with a variety of actuators such as solenoids and piezoelectric actuators.

Finally, in a particularly preferred design of the invention, the electrical circuit for detecting by electrical variation whether the nozzle is open or closed comprises an electrically resistive coating, such as a diamond-like coating (DLC), applied to at least one of the valve seat and the region of the valve member cooperating with the valve seat or to an element incorporated in the valve member.

The conductor need not necessarily be guided through an isolation member for the actuator. For example, the conductor may be directed parallel to the axis of the actuator in an outer region of the body of the actuator. In this case, the contact member may comprise a conductive disc or a radially directed element, and the electrical link comprises an insulated conductive element arranged substantially parallel to the axis of the valve member but substantially further from the axis than the conductor. Thus, the radially directed contact members facilitate a radial offset between the conductor and the electrical link.

Drawings

The invention will now be described in more detail, by way of example only, with reference to embodiments of the invention illustrated in the accompanying drawings, in which:

FIG. 1 shows an axial cross-section of a fuel injector according to the present disclosure;

FIG. 2A shows a detailed axial cross-section of a central portion of the fuel injector of FIG. 1 on an enlarged scale and illustrates an arrangement of a circuit for detecting nozzle opening and closing;

FIG. 2B shows a detailed axial section on an enlarged scale of the central part of a fuel injector similar to that of FIG. 1, and the elastic link of the circuit for detecting the opening and closing of the nozzle is of an alternative design;

fig. 3 shows a schematic version of the alternative embodiment of fig. 1, in which the conductors of the circuit extend radially outside an isolation member for an actuator of a fuel injector, wherein fig. 3A illustrates the assembly, fig. 3B shows the circuit separated from the injector structure for ease of understanding, and fig. 3C shows an axial view of a contact member in the form of a conductive disc.

Fig. 4 shows a schematic version of the alternative embodiment of fig. 1, in which the conductors of the circuit extend radially outside the spacer element of the actuator for the fuel injector, wherein fig. 4A illustrates the assembly and fig. 4B shows the circuit separated from the injector structure for ease of understanding; and

fig. 5 shows a further alternative embodiment of fig. 1, in which the conductors of the circuit extend radially outside of the actuator for the fuel injector, wherein fig. 5A illustrates the assembly, fig. 5B shows the circuit separated from the injector structure for ease of understanding, and fig. 5C shows the conductors at the interface between the actuator and the isolation member for the actuator.

Detailed Description

Turning now to fig. 1 and 2A, there can be seen a fuel injector 10, the fuel injector 10 having a head 12, the head 12 being provided with an electrical connector 14, the electrical connector 14 being adapted to provide a connection 15 to and from an ECU for selectively energising an actuator 18 via

electrical connections

15, 102 to start and stop a fuel injection pulse. A fuel supply connection 20 is provided at the head 12 to supply fuel at an elevated pressure to the injector 10. A fuel return connection 22 is provided to return fuel at low pressure to a schematically shown fuel storage tank 24. At the end opposite the head 12, the injector 10 has a fuel injection nozzle assembly 26, the fuel injection nozzle assembly 26 having a nozzle body 41 provided with a nozzle opening 28 at one end. The valve member 32 is axially guided in the nozzle body 41 between the upper guide member 31 and the lower guide 29. The valve member 32 is adapted to be biased by a compression coil spring 36 to close against a valve seat 38 and inhibit fuel injection through the nozzle opening 28 or move away from the valve seat 38 to enable fuel injection through the nozzle opening 28. A valve seat 38 is provided in the lower guide 29 directly above the nozzle opening 28. The fuel passage 42 conveys fuel from the supply connection 20 to the nozzle opening 28. A branch (not shown) leads from the fuel passage 42 to the control chamber 34 and the end 33 of the valve member 32 remote from the valve seat 38 projects into the chamber 34. The fuel pressure in chamber 34 urges valve member 32 toward valve seat 38 when the nozzle is in the closed position. The control valve 52 is operated by the actuator 18 to allow fuel to pass from the control chamber 34 (via a passage not shown) to the return connection 22, thereby reducing the pressure in the chamber 34 so that the valve member 32 can move away from the valve seat 38 to the open position of the nozzle to enable fuel injection. The fuel injector further includes a circuit for detecting nozzle opening or closing by electrical variation. The loop extends between the electrical connector 14 and the upper guide member 31 and includes a resilient electrical link 126.

In the design shown in fig. 1, the nozzle body 41 comprises separate coaxially arranged upper and

lower guide members

29, 31. However, the upper guide member 29 and the lower guide member 31 do not have to be separate components, but they may be formed in one component.

Whether a single-piece design or a two-piece design is used, the valve member 32 has a generally conical sealing surface 40, which sealing surface 40 seats against the generally conical valve seat 38 of the lower valve guide member 29. When control valve 52 is operated to reduce the pressure in chamber 34, valve member 32 is able to move away from valve seat 38 within chamber 34 under the influence of the pressure of fuel in passage 42 to effect fuel injection through nozzle opening 28, i.e., into a cylinder of an associated combustion engine (not shown).

The basic operation of a fuel injector is well known to those skilled in the art and will therefore not be described further.

Fuel injectors 10 are typically supplied high pressure fuel from a common rail 54 (shown only in fig. 1) of an associated engine (not shown). Fuel is supplied from fuel tank 24 to common rail 54 by a low pressure pump 56 located in or at fuel tank 24 and by a high pressure pump 58 so that the elevated fuel pressure prevailing at fuel supply connection 20 is above about 2000 bar. One or more filters and fuel shut-off valves (neither shown) may be included in the fuel supply system, as is known. Also, in a multi-cylinder engine, each cylinder is equipped with a respective fuel injector 10, and these fuel injectors are connected to the common rail.

It will be seen from fig. 1 that the nozzle assembly 26 and control valve assembly 52 are located within a bonnet nut 96, and the actuator 18 and the lead wire 14 connected thereto are located in a bore drilled in the NHB 92 (nozzle holder body), to which the bonnet nut is connected by a threaded connection. The actuator 18, control valve 52 and

valve guide members

29, 31 have finely machined mating surfaces at the joints therebetween that are held together in a fuel tight manner by a bonnet nut 96, the bonnet nut 96 having internal threads 98 that engage external threads 100 on the NHB 92. Because of this configuration and the manufacturing tolerances involved, the actuator 18 may always have a slight angular misalignment relative to the control valve 52 and the nozzle assembly 26, which makes it difficult to ensure an electrical connection between the nozzle assembly and the ECU connection at the head 12 of the actuator.

When it is desired to detect an electrical parameter at the nozzle assembly, which would occur when valve member 32 moves away from valve seat 38 and engages valve seat 38, there must be an electrical connection from the nozzle assembly to ECU 16 so that ECU 16 can process the change and use the change to more accurately control the operation of the control valve 52 and thus the operation of fuel injector 10. The electrical circuit used to detect this change requires two connections. One of these two connections is easily realized by the material of the fuel injector as a ground connection which is connected to the ground connection for said actuator 18 and from there to the ECU via one of the wires 14 or to the common ground of the ECU by means of the cap nut 96 and/or the NHB 92. The other electrical connection must be an insulated connection that needs to be conducted through the fuel injector via a third wire 17 connecting the fuel injector to the ECU. This is a so-called closed loop electrical conductor which, together with the ground connection, enables closed loop control of the control valve 52 and thus opening and closing of the valve member 32 (i.e. movement of the valve member 32 away from and towards the valve seat 38).

Different ways of achieving a closed loop connection path forming an insulated part of a circuit for detecting whether a nozzle is open or closed by electrical change will now be discussed with reference to the drawings.

In the design shown in fig. 1 and 2A, the closed loop conductive path of the circuit includes an insulated conductor 110, the insulated conductor 110 extending from the head 12 of the fuel injector through a central bore 112 in the isolation member 102 for the actuator 18 to a location generally at a head end 114 of the actuator 18.

It should be noted that the spacer member 102 is actually part of the actuator 18 and is essentially an over-molded piece of insulating resin that controls the blades or leads 15 of the actuator (solenoid) 18.

In the design of fig. 1 and 2A, the insulated conductor 110 passing through the central bore 112 is bent radially outward (radially outward directed portion 116) and is located directly below a disk-shaped contact member 118 at the head end 114 of the actuator. The contact member 118, which comprises an axial disc surrounding the insulation member 102, is in this embodiment pressed against the end 116 of the electrical conductor 110 by an actuator clamping spring 120, i.e. a compression coil spring. The spring 120 surrounds the actuator spacer member 102 within the recess 122 of the NHB and bears on an insulating washer 124, which insulating washer 124 in turn presses the disc-like contact member into electrical contact with the bent end 116 of the conductor 110, from which bent end 116 the insulation is removed. The disc-shaped contact member 118 is insulated from the armature of the actuator 18 and the actuator isolation member 102 by a suitable electrical insulator (not shown in fig. 1 and 2). The conductor 110 is made of a metal wire and is insulated by a shrink sleeve or by overmolding it into the insulating resin of the isolation member 102, which forms part of the solenoid of the actuator. It may also be positioned alongside the solenoid control wire 15 and overmolded with resin at the same time. In this case, all of these wires pass through the central bore 112 of the isolation member 102, and the conductor 110 is also insulated from the wire 15. This enables a particularly compact arrangement.

Electrical contact with the bent end 116 occurs in a radially inner portion of the contact member 118.

The radially outer portion of the disc-shaped contact member 118 is in electrical contact with an insulating resilient electrical link 126 extending between the contact member 118 and one of the valve member 32 and the valve guide member 31. In this case, it is connected to the valve guide member 31 by a bore in the exterior of the body of the control valve 52, which is axially directed parallel to the central axis of the control valve 52. It will be appreciated that in the designs of fig. 1 and 2A, 2B, the electrical contact between the bent portion 116 of the conductor 110 and the contact member 118, and the contact between the electrical link 116 and the contact member 118, is highly sensitive to angular misalignment of the electrical link 126 and the conductor 110 (i.e., the bent end 116 thereof).

It is also contemplated that the conductor 110 may be welded or brazed to the contact member 118.

The design is such that the insulated electrical link passes through the NBH 92, obliquely through the hole in the upper portion 31 of the valve guide 30, and then through the valve member 32 to the conical seating surface 40 of the valve member 32. A layer or insulating layer (not shown) is provided at the conical seating surface 40 or at the conical mating seat of the valve guide and the resistance of the layer or layers varies in response to the contact pressure of the valve member against the valve seat 38 at the lower valve guide member 29. The lower valve guide member 29 forms a ground connection of the ECU together with the cap nut 96 and the NHB 92. Of course, an insulator must be provided between the valve member 32 and the upper and lower

valve guide members

29, 31 at other points where contact between these elements is likely to occur, for example, at the sliding surface of the valve member 32 near its lower end (which serves to guide the valve member 32 in the lower valve guide member 29).

In designs with two-part valve guides, insulation layers must be provided between the valve member 32 and the upper portion 31 and between the upper and lower

valve guide members

31, 29 and any associated structures so that there is a uniquely defined electrical path.

In this way, the closed loop link enables the ECU to measure the resistance between valve member 32 and valve seat 38 at valve seat 38. The return path of the circuit is through the valve member 32 to the fuel injector ground and ultimately to the ECU 16.

The electrical change detected by the ECU may be at least one of a resistance change, a potential change, and a current change.

The resilient electrical link 126 may be implemented in different ways. In the embodiment of the invention shown in fig. 1 and 2A, the elastic link 126 conveniently comprises a rigid conductor member 130 and at least one axial elastic conductor member 134 arranged in series with the rigid conductor 130. The axially resilient conductor member may include a spring contact member 134. This may take the form of a resilient element, such as a helical spring or a leaf spring, or may be formed to be resiliently supported at the rigid conductor member 130 by means of a solid contact pin as shown in fig. 1 and 2A. In this example, the rigid conductor member is a conduit rod or can having a hollow end that supports a coil spring (not shown) that urges the contact pins 134 outwardly. The resilient electrical link is provided with an insulator except at the free end of the contact pin.

Fig. 2B shows an alternative design of the resilient link 126, but is otherwise substantially the same as the design of fig. 1 and 2A, so that details of the fuel injector 10 not related to the resilient link will not have to be repeated, it being understood that the previous description also applies to fig. 2B.

In the embodiment of fig. 2B, the resilient electrical link 126 is a coil spring 136. The coil spring 136 includes: a first portion 138, the first portion 138 having coils in contact whereby the portion is axially inelastic, at least in compression; and a second portion 140, wherein the coils of the spring are distanced from each other, whereby said second portion is elastic in both compression and tension. In the design of fig. 2B, the helical spring 136 is further provided with a third portion 142, wherein the coils of the spring are distanced from each other, whereby the third portion 142 is also axially resilient in the same way as the second portion 140. As shown, the first portion 138 is a central portion of the coil spring 136, the second portion 140 is an end portion of the spring in contact with the upper guide member 31, and the third portion 142 is an end portion of the spring 136 in electrical contact with the contact member 118. However, it is not necessary to provide three different parts, but only two may be provided, one being rigid and one being resilient enough. It is not important where the resilient portion is located, it may be located at either end of the rigid portion, or indeed centrally disposed between the two rigid portions. Obviously, the ends of the coil spring contacting the contact member 118 and the valve member 32 need to be exposed to ensure electrical contact, otherwise they would be separated from the structure of the fuel injector 10 by a suitable electrical insulator. One way to do this is to use an insulating shrink tube to surround the electrical link 126.

In an alternative embodiment shown in fig. 3A-3C, the conductor 110 is directed parallel to the axis of the actuator 18 in an outer region 132 of the isolation member 102 of the actuator 18. The contact member 118 may likewise comprise an axial disc. In this case, the conductor 110 is conveniently welded or brazed to the radially inner portion of the disc-shaped contact member 118. The electrical link 126, which can be designed in any of the ways described with reference to fig. 1 and 2, conveniently contacts the radially outer region of the disc-shaped contact member 118. The enlarged end view of the disc-shaped contact member 118 with the nose 119 shown in fig. 3C illustrates that the design is also insensitive to angular misalignment of the insulated conductor 110 and the electrical link 126. Also, all components are insulated to prevent unnecessary connection to ground.

Fig. 4A and 4B show another embodiment in which the insulated conductor 110 is likewise directed parallel to the axis X of the actuator 18 in the outer region 132 of the isolation member 102 of the actuator 18. Here, the contact member 118 includes a radially directed element and the electrical link 126 includes an insulated conductive element that is arranged generally parallel to the axis of the valve guide 30, but at a larger radius of the insulated conductor 110. In this embodiment, the insulated conductor 110, the insulated contact member 118, and the insulated electrical link 126 can be made as a unitary body. The electrical link 126 preferably has a resilient contact with the upper valve guide member 31.

Finally, fig. 5A-5C illustrate another alternative embodiment in which the insulated conductor 110 likewise passes through the central axial bore 112 of the isolation member 102 for the actuator 18. At the interface between the isolation member 102 and the actuator 18, the insulator is also bent outwardly to form an outwardly bent end 116. In this embodiment, the disk-shaped contact member is also pressed against the exposed conductive surface of the conductor 110. This configuration is similar to the configuration shown in fig. 2, and the coil spring for the clamping actuator can likewise act on the disk-shaped contact member 118 via an insulating washer, although these details are not shown in this figure. However, fig. 5A and 5B show that the connections 15 to the ECU are located in respective axially parallel bores of the spacer member 102 that are separate from but parallel to the central bore 112 that houses the closed loop link 104. Thus, this embodiment differs from the embodiment of fig. 1 and 2A, 2B in that the disc-shaped contact member 118 is here welded to the conductive link 126, and the wires 15 and the conductors 110 extend in separate holes of the support member.

The invention also relates to a fuel injector 10 of the type described in combination with an ECU 16, wherein an actuator 18 from the ECU 16 to the fuel injector 10 has first and second connections 15, one of said connections 15 being a ground connection and the other being a power connection, and a third connection 17 for connecting the circuit (closed loop link 104) to the ECU 16.

When reference is made in this specification to upward or downward or upper or lower or use of an elevation or related expression, this should be understood to refer to the vertical position of the fuel injector when the nozzle opening 28 is at the bottom. However, this does not mean that the fuel injector cannot be used in other orientations and should not be construed restrictively.

The final portion of the conductor at the actuator end of the isolation member may be bent at approximately a right angle to contact the contact member. This is a relatively simple design that easily tolerates misalignment.

List of reference numerals

10 fuel injector

12 head of fuel injector

14 electric connector

15 connection from ECU 16 to actuator 18

16 ECU

17 connection from closed loop link to ECU 16

18 actuator, solenoid or piezoelectric element

20 fuel supply connection to a fuel injector 10

22 fuel return connection from fuel injector 10

24 Fuel storage tank

26 nozzle assembly

28 nozzle opening

29 lower part of valve guide 30

31 upper part of valve guide 30

32 valve member, needle

33 end of valve member 32

34 chamber in valve guide 30

36 spring biasing valve member 32 toward valve seat 38

38 valve seat

40 generally conical sealing surface of valve member 32

41 nozzle body

42 fuel path

52 control valve

54 common rail

56 low pressure pump

58 high pressure pump

92 nozzle holding body of fuel injector 10

94 lower portion of fuel injector 10

96 cap nut

98 internal threads of the collet nut 96

100 upper portion 92 outer sleeve 106 external threads

102 insulated electrical connector

110 insulated conductor of closed link

112 center hole of isolation member 102

114 head end of actuator 18

116 the radially outwardly bent end of the conductor 110

118 contact member of a closed link

120 coil spring for clamping actuator 18

122 receive a recess in the outer sleeve 106 of the coil spring 120

124 shim

126 resilient electrical link

130 rigid part of the closed loop link 126

132 isolating an outer region of the component 102

134 spring contact member

136 form the coil spring of the resilient electrical link 126

138 first part of coil spring 136

140 second portion of coil spring 136

142 third part of coil spring 136

Claims

1. A fuel injector (10), the fuel injector (10) having:

-a head (12), the head (12) being provided with an electrical connector (14), the electrical connector (14) being adapted to provide an electrical connection (15) to and from an ECU (16) to selectively energize the actuator (18) via the electrical connections (15, 102) to start and stop fuel injection pulses;

-a fuel supply connection (20), the fuel supply connection (20) being for supplying fuel at an elevated pressure into the fuel injector (10);

-a fuel return connection (22) for returning fuel at low pressure;

-a fuel injection nozzle (26) assembly having:

-a nozzle body (41) provided with a nozzle opening (28) at one end;

-a valve member (32) axially guided in the nozzle body (41) between an upper guide member (31) and a lower guide (29), the valve member (32) being adapted to be biased to close against a valve seat (38) and inhibit fuel injection through the nozzle opening (28), or to move away from the valve seat (38) to enable fuel injection through the nozzle opening (28);

-a fuel passage (42), which fuel passage (42) conveys fuel from the fuel supply connection (20) to the nozzle opening (28);

-a branch from the fuel passage (42) to a control chamber (34), an end of the valve member (32) remote from the valve seat (38) protruding into the control chamber (34), so that fuel pressure in the control chamber (34) pushes the valve member (32) towards the valve seat (38) when the nozzle is in a closed position; and

-a control valve (52), which control valve (52) is operated by the actuator (18) to allow fuel to pass from a control chamber (34) to the fuel return connection (22), thereby reducing the pressure in the control chamber (34) and enabling the valve member (32) to move away from the valve seat (38) when the nozzle is in the open position, thereby enabling the fuel injection,

characterized in that the fuel injector further comprises a circuit for detecting by electrical variation whether the nozzle is open or closed, the circuit extending between the electrical connector (14) and the upper guide member (31), the circuit comprising a resilient electrical link (126),

wherein the resilient electrical link (126) comprises a rigid conductor member (130) and at least one axially resilient conductor member (134) arranged in series with the rigid conductor member (130),

wherein the circuit further comprises: a conductor (110), the conductor (110) being arranged along the electrical connection (15, 102) for the actuator at a position substantially at the head end of the actuator (18); a contact member (118), the contact member (118) being located at the head end of the actuator (18), in electrical contact with the conductor (110); and the resilient electrical link (126), the resilient electrical link (126) extending axially along the actuator from the contact member (118) to the upper guide member (31),

wherein the contact member (118) is a disc member generally disposed on the head of the actuator (18), the disc member having an upper or lower surface in electrical contact with the conductor (110), and the lower surface being in electrical contact with the resilient electrical link (126), and

wherein the contact member (118) is urged into contact with an end (116) of the conductor (110) at the head end of the actuator (18) by a compression spring (120).

2. The fuel injector (10) of claim 1 wherein the conductor (110) and the resilient electrical link (126) are directed parallel to a longitudinal axis (X) of the actuator.

3. A fuel injector (10) as claimed in claim 1 or 2, wherein the electrical connection (15) for the actuator (18) is electrically isolated by means of an isolating member (102) extending through an axial bore (112), the axial bore (112) being provided in the injector body between the head (12) and the actuator (18), and wherein the conductor (110) for insulation of the circuit is arranged within the isolating member (102) along the electrical connection (15).

4. A fuel injector (10) as claimed in claim 1 or 2, wherein the electrical connection (15) for the actuator (18) is electrically isolated by means of an isolating member (102) extending through an axial bore (112), the axial bore (112) being provided in the injector body between the head (12) and the actuator (18), and wherein the conductor (110) for insulation of the circuit is arranged outside the isolating member (102) along the isolating member (102).

5. The fuel injector (10) of claim 1 or 2 wherein an end (116) of the insulated conductor (110) opposite the head (12) is bent at approximately a right angle to contact the contact member (118).

6. A fuel injector (10) as claimed in claim 1 wherein the disc member is provided with a nose portion (119) extending radially beyond the actuator, the resilient electrical link (126) being in contact with a bottom surface of the nose portion (119).

7. The fuel injector (10) of claim 1 or 2, wherein the conductor (110) is welded or soldered to the disc member.

8. A fuel injector (10) as claimed in claim 1 or 2, wherein the circuit extends in a straight direction parallel to and radially offset from a longitudinal axis (X) of the fuel injector, the circuit extending from the head (12) of the fuel injector to the upper guide member (31).

9. The fuel injector (10) of claim 1 or 2 wherein the resilient electrical link (126) is a coil spring (136).

10. The fuel injector (10) of claim 9 wherein the coil spring (136) comprises: a first portion (138) having coils in contact, the first portion being non-axially resilient; and a second portion (140) in which the spring coils are separated from each other, the second portion having elasticity.

11. A fuel injector (10) as claimed in claim 10 wherein the coil spring (136) is further provided with a third portion (142), the spring coils of the third portion (142) being separated from each other, the third portion (142) being axially resilient, and wherein the first portion (138) is a central portion of the coil spring (136), the second portion (138) is an end portion of the coil spring in contact with the upper guide member (31), and the third portion (142) is an end portion of the coil spring (136) in electrical contact with the contact member (118).

12. A fuel injector (10) as claimed in claim 1 or claim 2 wherein the electrical circuit comprises a resistive coating applied to at least one of the valve seat (38) and a region of the valve member (32) cooperating with the valve seat (38) or an incorporated element in the valve member (32).

13. The fuel injector (10) of claim 12 wherein the resistive coating is a diamond-like coating (DLC).