DE102016219189B4 - Determining a solenoid valve opening time - Google Patents

Abstract

Method for determining an opening time (tö) at which a solenoid valve, having a coil (41), of a fuel injection system of an internal combustion engine (37) opens completely, the method comprising:in a phase (B) of an opening process, applying a predetermined voltage (21) to terminals of the coil (41) according to a timing to regulate a predetermined current (19) through the coil (41) of the solenoid valve (37);determining a point in time (tw) of a timing change at which the timing changes from a first timing ( Δt1, Δt2) changes to a second timing (Δt); anddetermining the opening time (tö) based on the time (tw) of the clock change, the opening time (tö) being determined as the sum of the time of the clock change (tw) and a fixed time interval (Δtf).

Description

The present invention relates to a method for determining an opening time of a solenoid valve, a method for operating a solenoid valve having a coil for injecting fuel into a cylinder of an internal combustion engine, and an engine control unit which is designed to carry out one of the preceding methods.

The metering and delivery of fuel through fuel injection systems in internal combustion engines to generate a defined fuel-air mixture can be subject to a variety of causes of tolerances. If a valve with an electromagnetic drive is used for fuel injection, it is called a solenoid valve.

• - Gesamtansteuerdauer des Ventilantriebs
• - Toleranz-behaftete Dauer des Verzuges beim Öffnen des Ventils (Reaktionszeit des Ventils zwischen Ansteuerbeginn und messbarem Beginn der Kraftstoffzumessung)
• - Toleranz-behaftete Dauer des Verzuges beim Schließen des Ventils (Reaktionszeit des Ventils zwischen Ansteuerende und messbarem Ende der Kraftstoffzumessung)

A significant contribution to the overall tolerance of the injected fuel mass can be based on the deviation of the actual injection duration of the injection valve from the nominal injection duration for a defined electrical activation duration of the valve drive. The total injection duration of the injector can depend on the following variables:

• - Total activation time of the valve drive
• - Tolerance-related duration of the delay when opening the valve (reaction time of the valve between the start of control and the measurable start of fuel metering)
• - Tolerance-related duration of the delay when closing the valve (reaction time of the valve between the end of the control and the measurable end of the fuel metering)

Production and operation-related tolerances of the components of an injection system can affect the deviation of the actual total injection duration from the expected (nominal) total injection duration and thus the fuel quantity or fuel mass actually metered into the combustion air. Knowing the valve-specific total injection duration opens up the possibility of controlling to a target value and thus reducing the influence of component tolerances on the injection mass accuracy. This requires information about the actual duration of the individual parts of the total injection duration mentioned above. The determination and control of the total control duration of the valve drive and/or the duration of the delay when closing the valve can be used conventionally for controlling injectors.

There are conventional solutions for determining and controlling the duration of the delay when opening the valve, which either do not achieve the necessary accuracy to significantly reduce the fuel mass tolerance or are not sufficiently robust against incorrect control when used alone, or with sufficient accuracy and robustness through a alternative method for determining the duration of the delay when opening the valve must be monitored due to legal regulations.

US 2014/0012485 A1 discloses a method for determining the opening time of a fuel injector, wherein a time curve of the current strength flowing in the coil is detected, a current integral is determined as a function of time and a time is determined at which the current integral reaches at least a predefined current integral reference value. The specific time is the opening time of the control valve.

The pamphlet DE 10 2007 034 768 B3 shows an electric lifting magnet with a circuit arrangement that generates an actual lift signal and an excitation circuit that applies an excitation current to the lifting magnet or its coil, which can be controlled or regulated as a function of a desired lift signal and/or the actual lift signal. The excitation circuit has a two-point controller that regulates the excitation current, which is connected on the input side to an excitation current set value transmitter and an excitation current actual value transmitter and, on the output side, actuates a switch that can be switched between closed and open states, which in its electrically closed state controls the lifting magnet with an electrical Connects excitation voltage source and electrically separates it from the excitation voltage source in its open state. The excitation current setpoint generator is designed as a controller which processes the switching frequency of the two-point controller or the switch actuated by it as an actual stroke signal and compares it with a definable setpoint stroke signal and regulates the setpoint signal for the excitation current accordingly.

In the DE 197 42 038 A1 a method for detecting the status of a solenoid valve is described, the winding of the solenoid valve being supplied with current by a switching controller in two-point operation. A high current is passed through the windings of the solenoid valve to switch it on, and a reduced current is passed during holding operation. In order to detect a faulty drop in the armature during holding operation due to external mechanical shocks, the resulting increase in the control frequency of the switching regulator is evaluated for error detection.

The DE 42 37 706 A1 shows a device for detecting the moment of impact for the anchor a solenoid valve. For this purpose, the coil of the solenoid valve is supplied with a clocked excitation current and the change in the pulse duty factor of the excitation current is evaluated at the point in time at which the armature of the coil impacts.

It has been observed that conventional methods and systems for determining an opening time of a solenoid valve do not provide reliable and accurate values of the opening time in all situations and under all conditions.

It is therefore an object of the present invention to provide a method for determining an opening time at which a solenoid valve having a coil opens completely, a method for operating a solenoid valve having a coil for injecting fuel into a cylinder of an internal combustion engine, and an engine control unit. wherein an opening time of a magnetic valve can be determined reliably and with sufficient accuracy, in particular under the condition that the magnetic valve has to open under high pressure. Furthermore, it is an object of the present invention to provide a method for controlling or operating a solenoid valve for injecting fuel, in which a target quantity of fuel can be injected with higher reliability into a combustion chamber of a cylinder by operating the solenoid valve.

The object is solved by the subject matter of the independent claims. The dependent claims specify particular embodiments of the present invention.

According to one embodiment of the present invention, a method is provided for determining an opening time at which a solenoid valve having a coil opens completely, the method having, in a phase of an opening process, applying a predetermined voltage to terminals of the coil according to a clocking in order to to regulate a predetermined current through the coil of the solenoid valve, determining a point in time of a clock change at which the clock changes from a first clock to a second clock, and determining the opening point in time based on the time of the clock change.

The method can be carried out, for example, by an engine control device according to an embodiment of the present invention. The method can be implemented in hardware and/or software. In particular, the method can be implemented at least partially by a computer program that can be loaded into an engine control unit and executed by it.

At the opening time, a maximum flow through the corresponding opening of the solenoid valve is made possible. The opening time corresponds to the time at which the maximum flow through the solenoid valve is reached for the first time (for the opening process under consideration).

The solenoid valve can have a coil which can move an armature axially in a center when the coil is energized. A needle can be attached to the armature, which in particular has a spherical end which is able to close an opening or can open the opening for the flow of fuel when the coil is energized, so that the armature moves along a moves in the axial direction of the coil. The solenoid valve can in particular be designed to open under high pressure (of the fuel). The pressure of the fuel (against which the spherical end of the needle is opened) can be between 300 bar and 435 bar. To open, the solenoid valve can be opened in particular against the pressure of the fuel and the force of a spring or can counteract these forces.

The method is directed to an opening operation of the solenoid valve, starting from a closed state of the valve and moving the needle in the direction of opening the valve by actuating the coil. The opening process may include several phases, such as a first A phase, a second B phase and a third C phase. The phase considered first to determine the opening time may correspond to phase B.

The predetermined voltage can be applied to the coil for a specified time and then removed from the terminals of the coil for a specified different time. In this way, the coil can be subjected to a voltage according to a temporal voltage pattern or a temporal voltage curve, whereby a certain current through the coil is set, which is dimensioned in such a way that the specified current is reached (in particular so that the actual current only increases slightly or below deviates from the specified current) . The specified current can thus be understood as a control target in this phase. It cannot be ruled out that the current actually flowing through the coil deviates (up or down) from the specified current. The current actually flowing through this coil can therefore easily be around the specified current fluctuate, whereby amplitude and oscillation frequency can be influenced by the type of control.

Switching the voltage or the specified voltage on and off can be referred to as clocking. The clocking can change within the phase (in terms of the durations of switching on and off) and the change in clocking is detected according to this embodiment and used to determine the opening time. The first clocking can e.g. by a first period or switch-on time(s) (time period for which the specified voltage is applied to the coil without interruption) and/or switch-off time(s) (time period for which no voltage is applied to the terminals of the coil created) be characterized. The clocking can change within the phase in order to ensure the control goal of achieving the specified current.

The timing change can be caused by the fact that the needle of the solenoid valve moves during the first phase of the opening process, so that it is in different positions at different times during the phase of the opening process. A magnetic field built up in a preceding phase can also change, in particular diminish, during the opening process. The detection of the point in time of the timing change can thus correlate in time with the traversing position of the needle.

An inventive idea of the method lies in recognizing the point in time of the described deviation in the switching duration by measuring the switching duration and switching times and using it as a controlled variable or for plausibility or diagnostic purposes.

The change in clocking can also be caused by a change in the electromagnetic properties of the coil drive when the valve opens.

The opening time is determined as a sum of the time of the timing change and a fixed time interval. It has been observed from test series that the opening time, as it can be determined by determining the flow rate, is a fixed time interval after the time of the timing change. This time shift of the opening time from the specific time of the timing change can remain unchanged for further, later opening processes. However, the fixed time interval may be specific to the type of solenoid valve used. Thus, two different types of solenoid valve can have two different fixed time intervals. In this way, the opening time can be determined in a simple manner.

• Erfassen von Anschalt- und Abschaltzeitpunkten der Spannung;
• Bestimmen von Zeitdifferenzen jeweils zwischen einem Anschaltzeitpunkt und einem ersten Abschaltzeitpunkt nach dem Anschaltzeitpunkt;
• Vergleichen mindestens einer ersten Zeitdifferenz der Zeitdifferenzen mit mindestens einer darauffolgenden zweiten Zeitdifferenz der Zeitdifferenzen; und
• Bestimmen desjenigen Abschaltzeitpunktes als den Zeitpunkt des Taktungswechsels, bei dem die relative Abweichung der zugehörigen ersten Zeitdifferenz von dem Durchschnitt der zweiten Zeitdifferenzen einen vorgebbaren Wert übersteigt; oder
• Bestimmen desjenigen Anschaltzeitpunktes als den Zeitpunkt des Taktungswechsels, bei dem die relative Abweichung der zugehörigen zweiten Zeitdifferenz von dem Durchschnitt der ersten Zeitdifferenzen einen vorgebbaren Wert übersteigt.

Z.B. kann das Verfahren aufweisen: Bestimmen desjenigen Abschaltzeitpunktes als den Zeitpunkt des Taktungswechsels, für den die zugehörige erste Zeitdifferenz (oder ein Durchschnitt mehrerer solcher ersten Zeitdifferenzen) größer als zwischen 130 % und 200 %, insbesondere größer als zwischen 150 % und 180 %, der zweiten Zeitdifferenz (oder ein Durchschnitt mehrerer solcher zweiten Zeitdifferenzen) ist; oder Bestimmen desjenigen Anschaltzeitpunktes als den Zeitpunkt des Taktungswechsels, für den die zugehörige zweite Zeitdifferenz (oder ein Durchschnitt mehrerer solcher zweiten Zeitdifferenzen) kleiner als zwischen 50 % und 80 %, insbesondere kleiner als zwischen 60 % und 70 %, der ersten Zeitdifferenz (oder ein Durchschnitt mehrerer solcher ersten Zeitdifferenzen) ist. Andere Vergleichsverfahren sind möglich.The determination of the point in time of the timing change can have the following steps:

• detecting turn-on and turn-off times of the voltage;
• Determining time differences in each case between a switch-on time and a first switch-off time after the switch-on time;
• comparing at least a first time difference of the time differences with at least a subsequent second time difference of the time differences; and
• determining that switch-off time as the time of the clock change at which the relative deviation of the associated first time difference from the average of the second time differences exceeds a predefinable value; or
• Determining that switch-on time as the time of the timing change at which the relative deviation of the associated second time difference from the average of the first time differences exceeds a predefinable value.

For example, the method can include: Determining that switch-off time as the time of the clock change for which the associated first time difference (or an average of several such first time differences) is greater than between 130% and 200%, in particular greater than between 150% and 180% second time difference (or an average of several such second time differences); or determining that switch-on time as the time of the clock change for which the associated second time difference (or an average of a plurality of such second time differences) is less than between 50% and 80%, in particular less than between 60% and 70%, of the first time difference (or a average of several such first time differences). Other comparison methods are possible.

The switch-on time of the voltage can be understood as the time at which the specified voltage (eg the battery voltage of a vehicle) is applied to the terminals of the coil. The time at which the voltage is switched off can be understood as the point in time at which the connections of the coil are electrically separated from the voltage supply, which provides the specified voltage. A plurality of switch-on and switch-off times within the phase of the opening process can be detected become. The detection can either include measuring these switch-on and switch-off times or, for example, registering control signals from a regulator which outputs switch-on and switch-off signals of this type in order to achieve the specified current.

The time differences determined may represent lengths of time that the predetermined voltage is applied across the terminals of the coil without interruption. Furthermore, further or different time differences can be determined, which can represent the length of time (n) for which the predetermined voltage is disconnected from the terminals of the coil. These other time differences can also be analyzed to determine whether they change over time. A change in these other time differences can also indicate a timing change and thus also indicate a timing change.

The first time difference can thus represent a first switch-on period and the second time difference can represent a second switch-on period, which (after being switched off in the meantime) can represent the first further switch-on period after the first switch-on period. If more than one first time difference is considered, a number of first time differences can also be averaged, provided the first time differences do not differ too much, for example by no more than 20%. Also, when more than one second time difference is considered, multiple second time differences can be averaged, such as when the multiple second time differences do not differ by more than 20%. If the first (e.g. averaged) time difference is greater than between 130% and 200% of the (e.g. averaged) second time difference, the solenoid valve is first clocked with a longer switch-on time and then clocked with a shorter switch-on time. In this way, the timing change and also the point in time of the timing change can be determined in a simple manner.

The second time difference may correspond to a standard turn-on period (which is repeatedly applied) as may be determined by the predetermined current, the resistance of the coil, and the predetermined voltage. Thus, the standard switch-on period can be specifically searched for in the voltage pattern. The point in time at which the standard turn-on period is relatively reliably maintained over time can also be searched for. This allows the method to be further refined.

The specified current, which can be interpreted as a target current in the phase, can be selected in such a way that a maximum opening of the magnetic valve is achieved, so that the magnetic valve is fully opened, so that a maximum flow through the magnetic valve is therefore made possible.

However, the complete opening of the solenoid valve does not necessarily have to be reached at the point in time at which the current actually flowing through the coil corresponds to the specified current, but can be reached later in time.

According to the embodiment of the present invention, this point in time is determined reliably and with good accuracy.

The method can also include operating the solenoid valve in a previous phase of the opening process that is prior to the phase, in which a higher voltage than the specified voltage is applied until a current threshold value that is higher than the specified current is reached, and/ or operating the solenoid valve in a phase of the opening process that follows the phase in time, in which the specified voltage is applied according to a cycle, so that a current value that is lower than the specified current is reached and in particular full opening is achieved.

The preceding phase temporally before the phase may be referred to as an "A" phase, and the following phase temporally subsequent to the phase may be referred to as a "C" phase. Such phases A, B, C can already be provided in conventionally available processes. A conventional injection system or solenoid valve and solenoid valve control method can thus be supported.

According to one embodiment of the present invention, a method is provided for operating a solenoid valve having a coil for injecting fuel into a cylinder of an internal combustion engine, the method having: performing a method according to one of the preceding embodiments and using the determined opening time as a controlled variable and/or for plausibility checking and/or for diagnosis and/or for limiting a signal analysis time window.

The internal combustion engine can include an Otto engine and/or a diesel engine, for example. The opening time can be compared with a target opening time, for example, and a deviation can be fed to a controller, such as a PID controller, which in turn outputs a control signal to close the solenoid valve in this way control (in terms of at least one control parameter) that the deviation becomes minimal.

A solenoid valve for injecting a defined quantity of fuel can thus be advantageously activated.

According to one embodiment of the present invention, the use of the specific opening time includes: determining at least one parameter, in particular predetermined current setpoints and/or current control hysteresis widths in the individual phases and/or a start time of activation of the solenoid valve for a next opening process depending on the specific opening time, and driving the solenoid valve according to the determined parameter.

The use of the specific opening time can also include determining a difference between the specific opening time and a target opening time and starting to drive the solenoid valve as a function of the difference in order to achieve the target opening time. In this case, specified desired current values in particular can remain unchanged in the individual phases. Controlling of the solenoid valve can thus be improved in a simple manner without also having to change other operating or control parameters.

According to one embodiment of the present invention, an engine controller is provided which is designed to carry out a method according to one of the preceding embodiments.

Furthermore, a computer program product is provided which contains instructions which, when executed by means of a processor, are designed to carry out a method according to one of the preceding embodiments.

• 1 illustriert Verläufe von Spannung, Strom und Injektordurchfluss, zur Erläuterung eines Verfahrens zum Bestimmen eines Öffnungszeitpunkts gemäß einer Ausführungsform der vorliegenden Erfindung; und
• 2 illustriert schematisch eine Motorsteuerung gemäß einer Ausführungsform der vorliegenden Erfindung und ein Magnetventil, welches ein als ein Injektor für eine Verbrennungskraftmaschine fungiert.

Embodiments of the present invention will now be explained with reference to the accompanying drawings. The invention is not limited to the embodiments described or illustrated.

• 1 illustrates curves of voltage, current and injector flow, to explain a method for determining an opening time according to an embodiment of the present invention; and
• 2 12 schematically illustrates an engine controller according to an embodiment of the present invention and a solenoid valve functioning as an injector for an internal combustion engine.

1 Figure 1 illustrates graphs 1, 3 and 5 in coordinate systems, where the abscissas 7 represent time and the ordinate 9 of graph 1 the voltage across terminals of a coil of a solenoid valve, the ordinate 11 in graph 3 the current in the coil of the solenoid valve and the Ordinate 13 in the graph 5 designates the flow of the fluid (eg fuel) controlled by the solenoid valve.

All three graphs or coordination systems in 1 is based on the same time axis 7 . Graphs 1, 3 and 5 illustrate the voltage curve (curves 15, 16, 18), current curve (curve 20) and flow curve (curve 22) of an opening process of a solenoid valve in phases A, B and C. In phase A between the points in time t0 and t1, a voltage according to curve 15 is applied or observed between the connection pins of the coil drive of the solenoid valve. In phase B between times t1 and t2, a voltage according to curve 16 is applied or observed between the connection pins of the coil drive of the solenoid valve. In phase C between times t2 and t3, a voltage according to curve 18 is applied or observed between the connection pins of the coil drive of the solenoid valve.

The activation process is divided into phases A and B. Phase A is ended once the setpoint value 17 valid for this phase (see graph 3) has been reached, and a change is made to phase B. Phase B has a new current setpoint 19, which is smaller than the current setpoint 17 in phase A. A controller then switches on a specified voltage 21 (e.g. the on-board voltage of a vehicle) in a clocked manner according to curve 16, so that the new current setpoint 19 in of phase B is reached.

In order to regulate this new desired current value 19, a relatively stable switching duration Δt (also referred to as the standard switch-on period) of the valve voltage can be observed and is necessary in the second half of phase B, i.e. in time range 23. The switching period (also referred to as the switch-on period) is given by the difference between a switch-off point in time 25 and a switch-on point in time 27 .

In a front region 29 of phase B, however, on-times Δt1, Δt2 are observed, which differ significantly from the on-time Δt. This can be explained by the change in the electromagnetic properties of the coil drive when the valve opens, which is why, with a suitable selection of the current parameters of phases A and B, there is a deviation from this stable switching duration Δt in the first half 29 of phase B is recognizable. Since this deviation is in temporal correlation to reaching the full fuel mass flow rate (see Diagram 5 in 1 ) a detection of the deviation of this switching period in real vehicle operation can be used either as a controlled variable or for plausibility or for diagnosis or to limit the signal analysis time window of other controlled variables or control methods as part of a valve opening control.

According to embodiments of the present invention, a point in time tw of a clocking change is determined, at which clocking is changed from a first clocking according to the switch-on periods Δt1, Δt2 to a second clocking according to the switch-on periods Δt. An opening time tö is determined based on the time tw of the timing change by forming the sum of tw and a fixed time interval Δtf. As can be seen from graph 5, maximum fuel mass flow rate 31 is reached from point in time to. This maximum fuel mass flow continues in phase C, to which a further setpoint current value 33 is assigned.

With the help of an electronic engine control unit 35, which 2 is illustrated schematically, a method for determining an opening time can be carried out according to an embodiment of the present invention. A solenoid valve 37 regulates a mass flow of fuel into a combustion chamber 39 of a cylinder of an internal combustion engine. The solenoid valve 37 has a coil 41 which moves a needle 43 in order to controllably close or open an opening 45 through which fuel flows into the combustion chamber 39 . For this purpose, a voltage is applied by the engine control unit 35 to the connection pins of the coil 41 via supply lines 47, so that the predetermined current threshold values 17, 19, 33 are reached in different phases A, B and C of an opening process.

The engine control unit 35 thus sets in a phase of an opening process (e.g. in phase B in 1 ) a specified voltage, for example the specified voltage 21, to terminals of the coil 41 in accordance with clocking in order to regulate a specified current, for example the specified current 19 through the coil of the solenoid valve 37. In addition, the engine control unit 35 determines a time tw of a timing change, at which the timing changes from a first timing (switch-on duration Δt1, Δt2) to a second timing (eg switch-on duration Δt). The engine controller 35 also determines the opening time tö from the time tw of the timing change.

By appropriately changing the control parameters, such as current setpoints or current control hysteresis widths of phases A and B, the position of the switching processes relative to the valve opening event can be changed and the time of the valve opening event can be determined more precisely as a result.

It is pointed out that embodiments of the invention have been described with reference to different objects of the invention. In particular, some embodiments of the invention are described with apparatus claims and other embodiments of the invention are described with method claims. However, it will be immediately clear to those skilled in the art upon reading this application that, unless explicitly stated otherwise, any combination of features belonging to one type of subject matter of the invention is also possible, in addition to any combination of features belonging to different types of objects of the invention.

It is pointed out that the embodiments described here only represent a limited selection of possible embodiment variants of the invention. It is thus possible to combine the features of individual embodiments with one another in a suitable manner, so that a large number of different embodiments are to be regarded as obviously disclosed for the person skilled in the art with the embodiment variants explicitly disclosed here.

Claims (9)

Method for determining an opening time (tö) at which a solenoid valve, having a coil (41), of a fuel injection system of an internal combustion engine (37) opens completely, the method having: in a phase (B) of an opening process, applying a predetermined voltage (21) to terminals of the coil (41) according to a clocking in order to regulate a predetermined current (19) through the coil (41) of the solenoid valve (37); determining a point in time (tw) of a timing change at which the timing changes from a first timing (Δt1, Δt2) to a second timing (Δt); and Determination of the opening time (tö) based on the time (tw) of the clock change, the opening time (tö) being determined as the sum of the time of the clock change (tw) and a fixed time interval (Δtf). procedure according to claim 1 , wherein the determination of the point in time (tw) of the clock change comprises: detecting switch-on and switch-off points in time (25, 27) the tension; determining time differences (Δt, Δt1, Δt2) between a switch-on time and a first switch-off time after the switch-on time; comparing at least one first time difference (Δt2) of the time differences with at least one subsequent second time difference (Δt) of the time differences; and determining that switch-off time as the time (tw) of the clock change at which the relative deviation of the associated first time difference from the average of the time differences exceeds a predefinable value; or determining that switch-on time as the time of the timing change at which the relative deviation of the associated second time difference from the average of the time differences exceeds a predefinable value. A method according to the preceding claim, wherein the second time difference (Δt) corresponds to a standard turn-on period determined by the predetermined current, the resistance of the coil (41) and the predetermined voltage (21). Method according to the preceding claim, in which the predetermined current (19) is chosen in such a way that a full opening of the solenoid valve (37) is achieved. A method according to any one of the preceding claims, further comprising: Operating the solenoid valve (37) in a previous phase (A) of the opening process, which is before phase (B), in which a higher voltage (15) than the predetermined voltage (21) is applied, until a current threshold value (17) that is higher than the predetermined current (19) is reached; and or Operating the solenoid valve (37) in a phase (C) of the opening process, which follows phase (B) in time, in which the specified voltage (21) is applied according to a cycle, so that a current value (33) that is lower than the specified Current (19) is reached and in particular full opening is reached. A method of operating a solenoid valve (37) having a coil to inject fuel into a cylinder (39) of an internal combustion engine, the method comprising: performing a method according to any one of the preceding claims; Using the determined opening time (tö) as a control variable and/or for plausibility checking and/or for diagnosis and/or for limiting a signal analysis time window. Method according to the preceding claim, wherein using the determined opening time (tö) comprises: Determination of at least one parameter, in particular predetermined desired current values and/or current control hysteresis widths in the individual phases and/or a start time of activation of the solenoid valve (37) for a next opening process as a function of the determined opening time; and Driving the solenoid valve (37) according to the determined parameter. Method according to the preceding claim, wherein using the determined opening time (tö) comprises: determining a difference between the determined opening time (tö) and a target opening time; and Beginning of the actuation of the solenoid valve (37) as a function of the difference in order to reach the target opening time, predetermined current threshold values in the individual phases in particular remaining unchanged. Engine control (35) which is designed to carry out a method according to one of the preceding claims.

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