JP2024507868A - How to control a solenoid operated fuel injector - Google Patents

Abstract

A method of controlling a fuel injector, the injector including an electrically controlled actuator, the actuator controlling the needle valve by movement of a needle to and from a valve seat of the needle valve. The method is configured to: a) plot the amount of fuel (Q) delivered by the fuel injector against the pulse width of an actuator actuation pulse sent to the actuator for the fuel injector; b) providing a modified plot of the amount of fuel delivered by the fuel injector versus the pulse width of the actuator actuation pulse based on the plot of step a); c) using the modified plot to subsequently control fuel injector activation; step b) includes d) identifying a spoon region in the plot of step a); and e. ) reproducing the plot of step a) without data from the spoon region of the plot of step a).
[Selection diagram] Figure 7

Description

TECHNICAL FIELD This application relates to a method of controlling a solenoid controlled fuel injector. This application applies particularly, but not exclusively, to direct acting fuel injectors and solenoid actuated fuel injectors. The present application further relates to a method of applying trim in controlling fuel injectors.

Current fuel injectors typically use an electric actuator (e.g., a piezo- or solenoid-operated actuator), and the electric actuator is used to operate a needle valve that is located away from the valve seat. The needle valve opens and closes to distribute fuel into the combustion chamber through the movement of the needle. Typically, an activation pulse of a particular duration (pulse width) is sent to an electric actuator (eg, a solenoid actuator) to operate a fuel injector. The amount of fuel injected into the combustion space depends on the duration of the pulse. The fuel injector may be of the type that dispenses fuel by directly moving a pintle/needle (device) such that the actuator moves away from the valve seat, for example against bias spring means; this is referred to as a direct injector; Seed injectors are used for both gasoline and diesel. Typically, the actuator is configured to move a pintle/needle device in which the needle is connected to a pintle as is well known in the art, and references to a pintle can be construed as references to a needle. Note that yes, and vice versa. The invention applies particularly to direct injectors of this type. The actuator may be a solenoid or piezo-controlled actuator.

In an alternative design, many current fuel injectors are hydraulically operated rather than a (e.g. solenoid) actuator that directly actuates the needle, and the actuator operates a hydraulic valve (system) that controls the pressure within the fuel injector. and indirectly moves the needle from the valve seat to selectively dispense fuel.

This type of (eg, gasoline) injector is compensated over time by learning, analyzing behavior, calculating correction values, and applying these trims during the next injector operation. This strategy is called ICLC (Injector Closed Loop Compensation).

Most injector controls do not take into account the physical pintle bounce of the gasoline injector, and this bounce results in a "spoon", a spoon-shaped area, or a plot of pulse length versus the injected fuel. A “downturn” occurs. These occur in the full lift area of the injector flow curve (pulse versus flow delivery curve) or at the beginning of the plot of pulse duration leading up to it. As used herein, the term "spoon" refers to a decrease in the amount of fuel delivered with a further increase in pulse duration, from a first point where the delivered fuel decreases with a small increase in pulse duration. Fuel delivered for the duration of the (activation) pulse (e.g. sent to a solenoid actuator) up to the point in time when the quantity Q returns to the peak value (locally it had before the first point in time, i.e. before the drop) This should be taken to mean one or more dips or spoon regions in the plot of Q.

For ECU control of fuel injection, spoons create problems because multiple pulse widths applied to the injector in the spoon area lead to the same fuel delivery making control difficult. Preferably, there is only one quantity linked to one pulse duration and no more. To solve this type of problem, a chart or plot (e.g. stored in the ECU as a MAP or relationship) of fuel quantity (delivery) to (e.g. solenoid) pulse width control is provided for control purposes. , the plot is such that with increasing pulse width, only the amount of fuel injected increases, i.e. it increases monotonically in the plot. Therefore, the injector behavior is then mapped using a monotonic pulse versus fuel quantity curve to meet this condition.

This kind of modified monotonic curve/plot is then used for ICLC trim decisions (pulse correction). This can be done, for example, by comparing to the target behavior (called MASTER) at some predetermined fuel delivery learning points (ICLC breakpoints).

Therefore, although a monotonic curve is essential for determining ICLC trim, the physical behavior of this injector is somewhat different due to the assumptions made by creating a monotonic curve. This difference is not compensated and gives a local error

Finally, no matter how many ICLC quantity learning points are selected, this phenomenon leads to poor ICLC performance in this particular area.

Typical methods of solving this kind of problem can either cause higher part-by-part sensitivity or minimize this effect by injector hydraulic optimization, which requires excessive force margin and hydraulic damping. It is to become

The purpose of the invention is to solve this type of problem.

In one aspect, a method of controlling a fuel injector is provided, the injector including an electrically controlled actuator, the actuator controlling the needle by movement of a needle to and from a valve seat of a needle valve. configured to control a valve, the method comprising:
a) determining, for the fuel injector, a plot of the amount of fuel (Q) delivered by the fuel injector against the pulse width of an actuator actuation pulse sent to the actuator;
b) providing a modified plot of the amount of fuel delivered by the fuel injector versus the pulse width of an actuator actuation pulse based on the plot of step a);
c) using the modified plot to subsequently control activation of the fuel injector;
Step b) is
d) identifying a spoon region in the plot of step a);
e) reproducing the plot of step a) without data from the spoon region of the plot of step a).
The plot generated in step d) may have gaps in the area of spoons. That is, there may be no stored relationship/MAP/plot data in these areas.

The spoon region represents pintle/needle bounce.
Step c) may include comparing data from the plot generated in step b) with data from a reference plot to determine trim data for said next control.

The actuator is a solenoid-controlled actuator or a piezo-controlled actuator.
The term stored "plot" or "curve" (e.g., regarding the amount of fuel Q delivered versus the (actuator) pulse width) can be interpreted as a parameter related to relational data (e.g., a stored relationship) The invention will now be described by way of example with reference to the accompanying drawings, in which: FIG.

FIG. 3 shows a plot/curve of pulse widths applied to a solenoid of a solenoid-actuated fuel injector. 2 shows a monotonic curve/plot of this kind based on the plot of FIG. 1; FIG. FIG. 3 illustrates control dependent on a nominal (eg, ideal) fuel injector response. FIG. 3 is a diagram showing errors in the plot of FIG. 2; FIG. 3 is a diagram showing the relationship between fuel error and fuel demand. FIG. 3 is a diagram showing an example of the present invention. FIG. 3 is a diagram showing an example of the present invention. It is a figure which shows the identification of a spoon area|region. It is a figure which shows the improvement result of the example of this invention.

As mentioned above, spoons create problems for ECU control because multiple pulse widths applied to the injector in the spoon area lead to the same fuel delivery making control difficult.

FIG. 1 shows a plot/curve 1 of the pulse width applied to the solenoid of a solenoid actuated fuel injector and the resulting amount of fuel injected for a typical injector. Note that aspects of the invention are equally applicable to injectors having piezo actuators rather than solenoid actuators.

As can be seen, there may be one or more spoon regions 2 in which the fuel quantity falls for a small increase in pulse width. The main spoon area is indicated by reference number 2a.

In summary, to solve this type of problem, a chart/plot (e.g. stored in the ECU as a MAP) of fuel quantity (delivery) versus pulse width control is provided for control purposes, and the plot is With increasing pulse width, only the amount of fuel injected increases, i.e. it seems to increase monotonically in the plot. Therefore, the injector behavior is then mapped using a monotonic pulse vs. fuel delivery (volume Q) plot/curve to meet this condition. FIG. 2 shows a monotonic curve/plot 3 of this kind superimposed by plot 1 of FIG.

This modified monotonic curve is then used for injector control, e.g. for ICLC trim decisions (pulse modification), and at some predetermined fuel delivery learning points (ICLC breakpoints). Compare with target behavior (called MASTER). FIG. 3 shows this type of control, where reference numeral 4 refers to a nominal (eg, ideal) fuel injector response. The applied trim is shown as arrow 5.

Although a monotonic curve is essential for determining ICLC trim, the physical behavior of this injector is Curve 1. This difference is not compensated for and gives a local error shown by the shaded area 6 in FIG. 4 (reference numbers as before).

FIG. 5 shows the relationship between fuel error and fuel demand, with the error being more prevalent in the spoon area indicated by the dashed ellipse 7. In the end, no matter how many ICLC quantity learning points are selected, this phenomenon will lead to poor ICLC performance in this particular area.

Invention Generally, in aspects of the present invention, the problem of poor ICLC performance at the beginning of full lift is solved by spoon avoidance.

The inventors have determined that the problem and solution can be formulated with the goal of creating a system with pulse-to-volume characteristics that avoids the spoon area and at the same time remains monotonic.

In conventional methods, a monotonic pulse/volume curve used all pulse widths to provide the desired fuel quantity within the fuel quantity/width (reference curve).

Instead, in accordance with the general aspect, certain areas of curve/plot 3 are avoided when determining the pulse width to be applied to a fuel injector for a certain amount of fuel. Therefore, ie the spoon area/area is avoided and such a pulse area (within the spoon) is not used when there is no other pulse width giving the same required amount of fuel. This is effectively done by generating and storing (e.g. in the ECU) a modified plot of fuel quantity versus pulse duration, which is based on the actual plot but effectively With the (data) portion removed, the resulting plot is therefore still monotonic. This modified plot is then used for control.

6 and 7 illustrate the invention. FIG. 6 shows a plot of the fuel quantity versus pulse curve (without monotonic correction) 1 as before. Spoon area (indicated by reference number 8). In our example, a new curve/plot 9 is created that does not contain the data in these spoon regions 8. A new (essentially monotonic) curve 9 (with substantially a gap 10 along the spoon region 8) is therefore provided, as in FIG. 7, but still pulsed for any fuel delivery rate. This is not a problem since the width is determinable.

The new curve (pulse/quantity characteristic) is therefore necessarily monotonic, giving only one pulse for one quantity. Due to this, when using this kind of plot 9 for control, some pulse widths are avoided, avoiding spoon and then volume bounce, ie pintle/needle bounce. Pulse avoidance can be performed using optimal adaptive ICLC learning points. For two specific learning points, one placed before the removed area and one placed immediately after, the pulse length jumps to the next useful pulse length.

Spoon area can be detected by more accurate analysis of hydraulic opening (HO) measurements versus pulse width (which is directly related to the amount of fuel delivered), see negative slope. The size (pulse width length) and amplitude (HO amplitude) of each spoon are recorded to fully know each spoon of each injector. FIG. 8 shows an example of a plot showing three spoons (Spoon 1, Spoon 2, Spoon 3) of varying parameters. HO is the time between opening and closing of the needle valve and various methods are known to those skilled in the art to determine these.

Individual Y-axes (delivery/HO-axes) for ICLC can be determined for each injector and for the start and end of each spoon. It avoids using undesirable pulse widths (which may be considered the time the actuator is on (e.g., high level Ton)) and provides a simple delivery response that perfectly matches the injector characteristics. Create a pulse width of 1. Delivery between two horizontal lines is prohibited and rounded to the nearest allowed point.

As a result, the ICLC performance on the spoon is greatly improved. Optimization is done on an injector-by-injector basis and also increases ICLC efficiency. FIG. 9 shows the relative error using aspects of the invention and is compared to the error of FIG.

Claims (6)

A method of controlling a fuel injector, the injector including an electrically controlled actuator, the actuator controlling the needle valve by movement of a needle to and from a valve seat of the needle valve. The method is configured to:
a) determining, for the fuel injector, a plot of the amount of fuel (Q) delivered by the fuel injector against the pulse width of an actuator actuation pulse sent to the actuator;
b) providing a modified plot of the amount of fuel delivered by the fuel injector versus the pulse width of the actuator actuation pulse based on the plot of step a);
c) using the modified plot to subsequently control activation of the fuel injector;
Step b) is
d) identifying a spoon region in the plot of step a);
e) reproducing the plot of step a) without data from the spoon region of the plot of step a). 2. The method of claim 1, wherein the plot generated in step d) has gaps within the area of the spoon. 3. A method according to claim 1 or 2, wherein the plot of step b) is monotonic. 4. The method of claim 3, wherein the spoon region represents pintle/needle bounce. 5. wherein step c) comprises the step of comparing data from the plot generated in step b) with data from a reference plot to determine trim data for the subsequent control. The method described in any one of the above. 6. A method according to any preceding claim, wherein the actuator is a solenoid-controlled actuator or a piezo-controlled actuator.