TECHNICAL FIELD

The present invention relates to fuel injectors and, more specifically, to fuel injectors which include a solenoid actuated control valve and a needle valve. The invention covers a system and method configured to determine the operational state of the needle valve.

BACKGROUND OF THE INVENTION

A fuel injector conventionally comprises a needle valve including a needle adapted to move away from a valve seat in an open position and then to contact the valve seat in a closed position. In hydraulic fuel injectors the needle

(needle/pintle arrangement) of the needle valve is controlled to open and close as a function of the pressure prevailing in a control chamber, which pressure is a function of the position of a solenoid actuated control valve. These small movements of the needle occur at high speed and steadily increasing performance levels now require feedback with respect to the actual position of the needle in order to provide optimum control.

Fuel injectors are known in which a sensor is arranged on the injector or where some surfaces of the components of the injector body are provided with resistive coatings, so that an electric resistance measurement can be performed

between two elements/components of the injector so as to determine when they are in and out of contact, consequently what the operating state of the injector is. In this way, in some injectors in order to perform closed loop control, the wiring of the injector and harness is designed such that means are provided to determine when injector components come into and out of contact with each other. Thus effectively these components act like switches and can be used for feedback for a closed loop control of the injector e.g. to rectify behavior drift. Accuracy of the feedback measurement is key for the efficiency of the closed loop control.

Some designs of fuel injector typically therefore provide a“switch” signal for the ECU, provided via an extra wire, where a signal on the wire provides means to detect when two moving parts in the injector system are in or out of contact with each other. Generally, fuel injector are made from metallic (conductive

components) so providing certain current paths when the components in operation are in contact with each other. This may be for example detecting when the valve needle comes into and out of contact with the valve seat thus whether the valve is open or closed; i.e. when the needle after opening (moving away from the valve seat) comes to its end (fully open) stop. Many prior art systems use such“switch “signal to determine the opening time of the injector needle valve or other components.

In the current state of the art, in order to provide the necessary feedback, such systems thus require a dedicated 3 ^rd wire inside the connector and specific wiring hardness to supply the injector closed loop link to the ECU so as to monitor the signal. So a 3-pin connector is used which requires a dedicated wiring hardness. A problem with this is that e.g. the harness need to be specially designed. In some cases, therefore different connector interfaces need to be used in respect of injector variants of injector with and without such ICL function.

It is an object of the invention to overcome such problems, and to provide feedback data on the operational state of the injector without a modified harness connector or extra wire.

SUMMARY OF THE INVENTION

In one aspect is provided A fuel injector including a solenoid controlled actuator, said solenoid controlled actuator including an a solenoid coil connected to high side and low side terminals, adapted such that activation of said actuator causes a valve needle of a needle valve to move away from a closed position where the valve needle tip is in contact with a valve seat, to an open position where the valve needle tip is away from said valve seat, said valve seat being connected to ground potential, and where said fuel injector defines a flow path for current to flow from a high side point of the inj ector via said needle and seat, to ground, when said needle valve is in the closed position, wherein said high side point is connected to the high side terminal of said solenoid via a first resistor.

The fuel injector may be adapted such that current cannot flow from a high side point of the injector via said needle and seat, to ground, when said needle valve is in the open position,

The injector may include a second resistor connected between a point between the first resistor and high side point, and ground.

Said first and/or said second resistor may be arranged in a connector (header) of the fuel injector.

In a further aspect is a system including an ECU, and a fuel injector as claimed above, connected thereto via a high side wire and a low side wire, said high and low side wires connected to respective high and low sides of said solenoid.

The system may include means to measure the current (I) flowing through said first wire to the high side terminal and also the current (II) flowing through the second wire from the low side terminal of said coil.

Said ECU may include said means to measure the current (I) flowing through said first wire to the high side terminal and also the current (II) flowing through the second wire from the low side terminal of said coil.

In a further aspect is provided a method of determining the operational state of said needle valve in such a system comprising: a) measuring the current (I) flowing through said first wire to the high side terminal; and,

b) measuring the current (II) flowing through the second wire from the low side terminal of said coil; and

c) processing the results of steps a) and b) to determine said operational state.

Step c) may determine the value of I-Il and determine the operational state based on said value. In step c) it may be determined that the needle valve is closed when said value is above a first threshold value and or second threshold value.

In step c) it may be determined that the needle is open when said value is below said first and/or second threshold value.

In step c) it may be determined that the needle is fully open when said value is above a third threshold value and partially open when below said third threshold value.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is now described by way of example with reference to the accompanying drawings in which:

- Figure la, b, c shows a simplified schematic representation of the lower

portion of a fuel injector in three operational states;

- Figure 2a, b, and c shows a timeline of the operation of the valve of figure 1;

- Figure 3 shows a fuel injector which can be used in conjunction with aspects of the invention;

- Figure 4 shows a system according to one example;

- Figure 5 shows various injector parameters of a system according to one example;

- Figure 6 shows a portion similar to the plot of Figure 5(d) DESCRIPTION OF THE PREFERRED EMBODIMENTS

Prior Art

Figures 1 and 2 show an existing signal monitoring system to detect operation of a fuel injector. Figure 1 shows a simplified schematic representation of the lower portion of a fuel injector in three operational states A, B , C. The figure shows the distal portion of the fuel injector 1 showing the needle 2, and valve seat of providing a needle valve. The needle is controlled dependent on actuation of a solenoid to slide up and down along an axis to move the needle tip to and away from a valve seat, to a closed and open needle valve position/state, thus allowing fuel to be selectively dispensed. The fuel injector may be a direct injection injector where an (e.g. solenoid) actuator directly moves a pintle/needle up and down, or the injector may be hydraulically operated where the needle is moved up and down consequent to pressure changes of fuel due to activation of a flow control valve.

In the figure, there is wiring/switch means to detect when the tip of the needle reaches the valve seat in a closed position (position A) shown in Figure 1 to form a closed contact (and thus a closed contact of a signal switch) to prevent fuel entering a combustion chamber, and when it is away from the valve seat. Thus the connection between the needle tip and the valve seat acts like a first switch. When closed, current can flow from a solenoid high side point via conductive components of the fuel injector via the needle to the seat and to ground There is additionally means to detect when the needle reaches its top position i.e. when the needle valve is fully open (position C) . This is detected by having a contact where a portion of the needle in its fully open position makes a contact to

(essentially a second switch) provide a flow circuit for current, to provide a signal. This requires an extra wire. The position is shown in figure lc and is designated position C. An intermediate position where there is no contact (neither of the “switches” are closed is shown in figure lb where the needle valve is partially open) is shown with B. Figure 2 shows a timeline of the operation of the valve of figure 1 and shows plots a, b, c of the plots of the activation pulse sent to the solenoid actuator of the injector valve (top plot - a) ) the amount of the fuel dispensed (middle plot - b) ) and the state of the needle valve by virtue of the switch signal bottom plot c). The needle valve is initially in a closed state (state A needle of needle valve contacting valve seat) switch closed bottom contact) on activation of the solenoid actuator the needle moves away from the valve (state B) so moving ballistically from bottom position to top position where the valve is partially open (needle partially open no contact). The needle then reaches the top position making contact with the second switch means here the valve is fully open state C - needle fully open top contact. Thereafter the valve starts to close and the needle move s down to a partially open position (state B) until it reaches the fully closed state (state A) where the needle tip reaches the seat and forms the contact of the first switch. Thus the switch signals fed back to the ECU allows valuable information to be gleaned for the purpose of feedback control such as the duration the valve is in the fully open position. However, there is a requirement for an extra wire which adds to the complexity e.g. of a wiring harness.

Invention

In aspects of the invention, is provided a system to detect injector needle valve events or the operation state of the valve (e.g. needle valve open or closed or even partially open) which does not require any (or very little) modification to the injector or any modification to the harness. Thus the system uses the existing wires and harness and connectors e.g. in respect of the High Side and Low Side connections, as will be described hereinafter

In one aspect is provided an injector where the needle /pintle arrangement is connected to the High Side voltage, which supplies voltage to the solenoid actuator, via contact of metal components. The valve seat is connected to ground. Effectively therefore this arrangement forms an inherent switch where there is a flow path for current from the High Side via the injector needle to ground when the needle tip contacts the valve seat (which is connected to ground), in a valve closed position. In other words current flows through this flow path to ground via the valve seat.

When the valve is open and the needle tip is away from the valve seat, current cannot flow from the high side to ground. Aspects of the invention make use of this such that it can be determined whether or not this effective switch is open (valve fully or partially open) or closed (needle valve closed) .

Methodology and a system according to examples used in conjunction with such injectors means there does not need to be provided any extra wire as will become clear later. In one aspect is provide a method which allows this determination and in one aspect is provided a simple circuit arrangement which can be used in the injector header to facilitate the method easily and which does not require harness and connector terminal modification.

The injector (body) construction itself does not need to be modified or specialized, and in some examples only the injector header or connector needs to be modified with the addition of simple circuitry.

Now a injector which can be used with aspects of the invention will be described. Such injectors are applicable to aspects of the invention described hereinafter and will be described now for completeness. The injector can be connected to the ECU by means of a connector head and harness.

Figure 3 shows a fuel injector which can be used in conjunction with aspects of the invention and is fully described in patent application WO 2017/1672627. Here similar to described above, there is (effective switch means) where current can flow from the high side connection (to the solenoid) via conductive components of the injector to the needle and then to ground when the needle tip is in contact with the grounded valve seat (closed position of needle valve) .

Conversely no such current can flow when the needle tip is away from the valve seat (when the needle valve is fully or partially open). This arrangement can be usually used optionally with a further switch to detect when the needle is in the fully open position and any case in prior art systems, an extra wire in the harness and modified harness to monitor the switche (s) for feedback to the ECU on valve position.

The figure shows a fuel injector for an internal combustion engine, comprising: an injection nozzle 12 with a body 16, in which a needle 14 is arranged that can be moved between a closed position, in which a first end 48 of the needle 14 rests on a seat 32 and seals injection openings 34 of the nozzle, and an open position, in which the first end 48 of the needle 14 is lifted from the seat 32 thereof in order to allow the injection; a control chamber 46 filled, during operation, with fuel so as to exert pressure on the second end 42 of the needle 14; a control valve 20 associated with the control chamber 46 allowing the fuel pressure in the control chamber 46 to be selectively varied and thus control an opening or closing movement of the needle 14, the control valve 20 being driven by an actuator; an upper guide 18 guiding the needle 14 axially by the second end 42 thereof; means for detecting the position of the needle 14, characterized in that the means for detecting the position of the needle comprise a first electric link in contact with the second end 42 of the needle so as to bring said needle to a predetermined electric potential; the needle 14 being mounted in the nozzle body so as to be able to move therein while being electrically isolated from the nozzle body 16, except for the region of the nozzle body seat 32, so that the needle is in electric contact with the nozzle body only in the closed position. Thus, the“closed” state of the detection circuit corresponds to the valve closed position when of the needle, when it rests on the body seat 32. The valve is in the“open” state as long as the needle is partially or fully lifted.

In summary there is effectively a switch provided in the injectors where the switch is in a closed state corresponding s to the needle valve closed position when of the needle 14, when it rests on the body seat 32. The switch and thus the needle valve is in the“open” state as long as the needle 14 is partially or fully lifted. Reference numeral 100 shows a thick line shows the flow path when the valve tip is in contact with the valve seat (i.e. needle valve and this switch of switch signal closed)

Invention

According to one aspect novel methodology and circuitry is used in conjunction with e.g. the injectors described above which can determine the operational state of the valve (open or closed) by determining whether the switch formed from the needle tip and valve seat (and thus the needle valve) is open or closed. Further the system and methodology has and uses a standard configuration of e.g. a two wire harness and a common 2 -pin wire connector (which is compatible with a standard wiring hardness).

So the system is adapted to (has means to) detecting whether the needle tip is in contact with the valve seat (closed position) and when it is away therefrom (open position) and which further uses a standard two wire connector and wiring harness for all injector applications. Further the system and method ca distinguish between whether the needle valve is in a fully of partially open position. Figure 4 shows a system according to one example. The figures shows schematically an ECU 200, or rather a simplified portion of the ECU for injector control purposes) on the left, and a solenoid controlled fuel injector 201 on the right, the injector which includes a needle valve. The ECU contains High Side Drive (HSD) circuitry connected to the HSD line /injector connection and Low Side Drive (LSD) circuitry connected to the LSD line and corresponding terminal of the injector. The injector 201 is shown in a highly simplified form and generally comprises the main body of the fuel injector (fuel injector itself) and the connector or header portion of the fuel injector shown generally by the dotted box 206, inside of which is shown the circuitry in the connector portion (connector head) of the injector. The ECU is connected to the injector via a two wires

(harness) to the high side terminal 211 of the header/connector and the low side terminal 212. The high side terminal is connected to the high side of the solenoid 202 and the low side terminal 212 is connected to the low side of the solenoid 202 of a solenoid controlled actuator of a fuel injector. It should be noted that in the figure the solenoid is found within the box 206 but the skilled person would be readily aware the solenoid is part of the man body of the injector and is shown in the box for clarity.

The main fuel injector is shown with the“switch” 203 described above which is the switch that represents in a closed position, contact between the needle tip (in the needle valve closed position) and the valve seat in the needle valve closed position; the switch in the open position represents the state where the needle tip is away from the valve seat (needle valve open position). Box 204 shows the mechanical position of valve needle tip and seat representing the switch. The fuel injector is controlled by the ECU. The (Injector Closed Loop) circuit inside the injector is such to provide i.e. current flow path when effective switch 203 is closed is sown by line 205. Reference numeral 206 shows circuitry of the arrangement which may be embodied i.e. provided in the injector head/header connector portion/module.

The fuel injector is solenoid controlled and thus includes a solenoid actuator as mentioned 202 with injector coil which is controlled by the ECU. The ECU has a high side with High Side Drive circuitry 210 and a low side with low Side drive circuitry 230, and corresponding connection/terminals with the injector (head) . It should be appreciated that some or all of the drive circuitry may be outside the ECU i.e. between the ECU and the injector. Thus the injector connection to the ECU/drive circuitry is via two connections/terminals.

According to one aspect there is preferably provided some simple circuitry which assists implementation of methodology. This is provided on the injector side e.g. in the injector connector or head, a resistor R1 electrically connected between the high side voltage terminal 211/high side terminal of the coil of the solenoid actuator, and a contact point 207 which is portion of the main fuel injector (body) which is connected to the high side voltage (terminal) (via resistor Rl).

That is to say the point 207 is effectively a (high side) portion/component of the flow path. Contact point 207 may be any point /component of the fuel injector which is in electrical contact e.g. via other conductive components to the needle or needle pintle arrangement. Additionally, and optionally there is a resistor R2 provided between a first point (between the high side connection of the flow path/point (207) and the resistor Rl), and ground. R2 is added to the circuitry to limit the current from the high side to ground via the needle seat area, which is undesirable and this current would otherwise be high and would e.g. cause an electro-erosion effect. Contact point (high side point) may be any portion of the fuel injector which is continually (in any operational position/state of the needle valve) in electrical contact with the valve (and generally thus as the same potential thereto) During injector activation, to open the valve, the High Side line is driven high according to an activation profile and current flows through the injector coil to open the control valve. The needle of the needle valve will consequently ascend and the needle tip will lift off the valve seat to an open position. The needle may reach its top stop in a fully open position of the needle valve. During the opening period there is little or minimal current flowing from the High Side to ground.

After activation the needle will descend until the tip thereof reaches the valve seat to a needle valve closed position. In the needle valve/switch closed position current can flow from the high side through injector component (e.g. though the solenoid bobbin to ground via the valve seat. Thus there is a flow path from the High Side Circuitry to ground as shown, through the needle tip/valve seat which acts like a switch when the valve is closed. The ECU is provided with means to measure the current to the injector through the high side connection and means to measure the current through the low side connection. In simple methodology according to example, analysis of these two currents can give information of the state of the needle valve (open or closed, and in some cases whether the valve is fully open or partially open.).

In the ECU are means to measure the current (I) from the High Side Drive to the High Side of the coli, 208, and means 209 to measure the current flowing through the solenoid coil which is that flowing along the LSD harness wire (II) from the coil.

The current through the low side II is the current through the coil. The current through the high side connection I is equal to the current through the injector coil II plus current through R1. Where there is resistor R2, the current through the high side connection I is equal to: the current through the injector coil II plus current through the resistor R2 (13) plus current flowing through the injector along flow path 205 from point 207 the ground (12) , 12 will be zero or close to zero when the switch is open and thus the needle valve in an open position when the needle tip is away from the valve seat. Thus 12=1-11-13 , and 12 +13 =1- II .

In one aspect I-E = I2+I3 is determined e.g. measured in the ECU (I and R are measured) and used to determine the state of the needle valve i.e. the effective switch state (open or closed when the needle tip is out of and in contact with, the valve seat respectively). I3 may be known.

Figure 5 shows various injector parameters along the same timeline and shows (a) plots of the activation pulse sent from the ECU to the injector, (b) the quantity of fuel injected, c) the injector (closed loop) switch state (in terms of voltage between the needle/injector portion connected to the high side terminal, and valve seat/ground). The bottom plot shows the corresponding value of I-Il (12 + 13) respectively. As can be seen the activation pulse comprises pre (main injection) injection pulses 501, followed by a main injection (longer) pulse 502, followed by a post (main injection) injection pulse 503. Consequent to each pulse the solenoid is actuated to open the needle valve to allow fuel to be injected into a combustion space as shown in (b). During the periods when fuel is injected when the needle valve is open, the voltage between the needle or high side to which the needle is in electrical contact, and the ground/valve seat goes high. When the needle valve is closed and the needle tip contacts the valve seat, conversely the voltage between needle and seat goes down to ground/zero level - see figure 5(c)..

When the needle valve is opened the value of I-Il goes from a (closed) high value of 0.2 A, to a lower value of 0.1 A. (in the figure 5(d)) . Conversely, when the needle valve is closed (the tip of the needle contacts the valve seat) the value of I- II goes from a low value to a high value. As seen in the needle valve open position, there is some leakage current which is why the value of I-Il is not zero.

When the needle valve is in the fully open position i.e. the needle or needle /pintle arrangement abuts the appropriate top/upper stop therefore, the leakage current can often be different (e.g. higher) than in the partially open state where the needle is in ballistic mode and does not contact the upper surface/stop . Thus the plot of I-Il can in circumstances with careful calibration or a sensitive accurate current measuring, also provide data on whether the needle valve is fully open, partially open or closed. Figure 6 shows a portion similar to the plot of Figure 5(d) showing the value of I- II (12+13) when the needle valve moves from a closed positon to a partially open to fully open. When closed the value I-Il is above a threshold Thl, when the valve is open (partially or fully) the value of I-Il moves below the threshold II to below a second threshold Th2. When the value goes below either Thl or Th2 the needle valve can be assumed to be open (fully or partially) and when above Thl or Th2 can be assumed to be closed. When the valve is assumed to be open but the value of I-Il is above third threshold Th3 the valve may be assume to be fully open as a leakage current in the fully open position causes some (higher) current to flow through the valve needle via the set to ground; compared to the partially open case. Consequently in a fully open position the value of I-Il is above a threshold TH3.

Aspects of the new methodology can be used with the existing simple architecture comprising 2 -wires or can be used in arrangements which uses a 3 ^rd wire where an effective additional switch is provided in the injector such that feedback is obtained by the ECU when the needle reaches it top position when the valve is fully open to detect full lift. So in examples, there is no need for extra wires between the injector and ECU and the position of the needle valve open or closed is determined/inferred solely by the ECU and measurements within the ECU

So the system does not need an extra wire and the harness and injector does not have to be substantially modified to provide the extra switch signal. So in examples there is no need for extra wires between the injector and ECU and the position of the needle valve open or closed is determined/inferred solely by the ECU and measurements within the ECU.

In contrast to the prior current is thus measured instead the voltage as I the existing ICL configuration electrical configuration inside ECU and connector.