EP1698777A2 - Method of operating an injector for an internal combustion engine - Google Patents

Abstract

Operating method involves monitoring system (46), which monitor whether the control member (16) is controlled outside of a projected fuel injection (36). A measure is executed depending upon the result of the monitoring. The injector is controlled with a signal (U), which influences the distance of a control member of the injector. Independent claims are also included for the following: (A) Computer program; (B) Electrical storage medium; and (C) Control unit for internal combustion engine.

Description

State of the art

The invention firstly relates to a method for operating an injector for an internal combustion engine, by means of which fuel can reach a combustion chamber, in which the injector is actuated with a signal which influences the state of an actuator of the injector. The invention also relates to a computer program, an electrical storage medium for a control and / or regulating device of an internal combustion engine, as well as a control and / or regulating device for an internal combustion engine.

A method of the type mentioned is known from the market. It is mainly used in motor vehicle internal combustion engines with direct fuel injection. In these, the fuel is injected from an injector directly into a combustion chamber associated with the injector. As an actuator for the initiation and completion of an injection, the injector has a piezoelectric actuator, which influences the switching position of a valve element, or a valve needle, by a change in length.

The operation of such an internal combustion engine is controlled or regulated by a control and regulating device, which also provides the drive signals for the actuators of the injectors of the internal combustion engine. To increase performance, more and more often the user or a workshop tries to influence the controls of the actuator of the injector by manipulation of the control and regulating device or by interposing additional control and / or regulating devices. Due to the associated additional loads of the internal combustion engine or the injectors can lead to accelerated wear and consequently to a failure of the engine. This can lead to unjustified warranty claims.

The object of the present invention is to develop a method of the type mentioned above so that such manipulations can be reliably detected.

This object is achieved in a method of the type mentioned in that outside of a scheduled injection is monitored at least temporarily, if the actuator is additionally controlled, and that depending on the result of monitoring a measure is performed.

In a computer program, an electrical storage medium and a control and / or regulating device of the type mentioned, the object is achieved accordingly.

Advantages of the invention

According to the invention, it has been found that by manipulations on the control and / or regulating device or by additional devices usually additional Injections are triggered, which should cause the desired increase in performance of the internal combustion engine. Such additional injections are reliably detected thanks to the method according to the invention. This makes it possible, when such additional control or injection has been detected, to take appropriate action. This can for example consist in an entry in a fault memory, but it can also be the further operation of the internal combustion engine locked.

As a result, in the clarification of warranty claims, evidence can be kept that relieve the manufacturer of the internal combustion engine by the said manipulations can be revealed. If further operation of the internal combustion engine is made impossible, damage to the internal combustion engine is even excluded from the outset, and emissions which are worsened by the additional injections are likewise prevented.

In an advantageous embodiment of the method according to the invention, it is proposed that at least one state variable of the actuator is detected at a time interval after a planned injection, that the detected state variable is diagnosed, and that the measure depends on the result of the diagnosis. Current state variables of the actuator are reliable indicators of the control state of the actuator, which in turn allows conclusions to be drawn on the actual control and / or regulating device not planned additional controls or injections. As state variables come in an electric actuator, such as a piezoelectric actuator, especially an am Actuator voltage applied, a discharge time, and / or an electrical resistance of the actuator in question.

In a further development, it is proposed that said time interval is variable. This increases the likelihood that additional injection following a scheduled injection will be detected. This probability is increased again if the time interval is random. This also "deception" with which the manipulations are to be obscured, made more difficult.

In the same direction aims that development of the method according to the invention, in which in an internal combustion engine having a plurality of cylinders, the state variable is detected at random at one or another cylinder.

Furthermore, it is advantageous if a test drive of the actuator is performed in the time interval after the injection, which causes no injection or terminates, and that the state variable is detected in connection with the test drive. This is based on the idea that when a control of the actuator by default detection operations are performed. In the case of a piezoelectric actuator, the voltage applied to the piezoactuator voltage is detected, for example, before a control, by which a change in charge of the piezoelectric actuator is effected. By means of such a test drive, it is therefore possible to use conventional and anyway existing detection routines for detecting inadmissible manipulations. As a result, the effort in implementing the method according to the invention is reduced.

It should be noted that the term "control" in a piezoelectric actuator only the actual process of the change in charge of the piezoelectric actuator is understood. However, the detection of the state variable can of course also take place between two such activations, for example between the loading and the subsequent unloading back into an idle state. On the other hand, in the case of an electromagnetic actuator, driving is present not only at the beginning and end of the injection but normally during the entire injection. It is understood that the method according to the invention can be used in both cases.

In this case, it can be checked during monitoring whether a state variable reaches or crosses a limit value. This can be programmed easily.

Preferably, the monitoring is performed within a working game only in such an angular or time range in which a torque can be generated by an injection. As a result, the monitoring effort is reduced and at the same time manipulations are reliably detected, since these are mostly used to increase performance and therefore only those additional controls, or Einspitzungen concern, through which a torque can be generated.

drawings

Figur 1

eine schematische Darstellung einer Brennkraftmaschine mit mehreren Injektoren mit jeweils einem Stellglied;

Figur 2

ein Flussdiagramm eines Verfahrens zum Betreiben der Brennkraftmaschine von Figur 1;

Figur 3

ein Diagramm, in dem eine am Stellglied eines Injektors anliegende Spannung über der Zeit für eine erste Untervariante des Verfahrens von Figur 2 aufgetragen ist;

Figur 4

ein Diagramm ähnlich Figur 3 für eine zweite Untervariante; und

Figur 5

ein Diagramm ähnlich Figur 3 für eine dritte Untervariante.

Hereinafter, particularly preferred embodiments of the present invention below With reference to the accompanying drawings explained in more detail. In the drawing show:

FIG. 1

a schematic representation of an internal combustion engine with a plurality of injectors, each with an actuator;

FIG. 2

a flowchart of a method for operating the internal combustion engine of Figure 1;

FIG. 3

a diagram in which a voltage applied to the actuator of an injector over time for a first sub-variant of the method of Figure 2 is plotted;

FIG. 4

a diagram similar to Figure 3 for a second sub-variant; and

FIG. 5

a diagram similar to Figure 3 for a third sub-variant.

Description of the embodiments

In Figure 1, an internal combustion engine carries the reference numeral 10. Overall, it is used to drive a motor vehicle, not shown in the figure.

The internal combustion engine 10 comprises a plurality of combustion chambers, of which only those indicated by reference numerals 12a and 12b are shown in FIG. Each combustion chamber 12a and 12b is associated with an injector 14a or 14b, which in turn comprises a piezoelectric actuator 16a or 16b. By the actuator 16a and 16b, the switching position of a valve element, not shown in Figure 1 of the injector 14a and 14b influenced by which ultimately the injection of fuel into the combustion chamber 12a and 12b is controlled. The injectors 14a to 14b are connected to a fuel pressure accumulator 18 ("rail"), in which the fuel is stored under high pressure. The fuel is conveyed into the fuel pressure accumulator through a high-pressure delivery system 20.

The actuators 16 of the injectors 14 are controlled by a control and / or regulating device 22. This includes, inter alia, not shown in Figure 1 Leistungsentstufen for generating the required for the control of the actuators 16 voltages. The control signals are determined in the control and regulating device 22 as a function of different input variables, for example a position of a crankshaft 24, which is detected by a sensor 26. Also, the position of an accelerator pedal, not shown, and various operating variables of the internal combustion engine 10 are taken into account in the determination of the drive signals in the control and regulating device 22.

In the internal combustion engine 10 shown, a manipulation device 28 was subsequently attached, by which additional activations of the actuators 16 of the injectors 14 are generated. As a result, the performance of the internal combustion engine 10 should be increased compared to the "production version". By such additional activations of the actuators 16, however, their wear is increased, and moreover, the emission behavior of the internal combustion engine 10 is significantly deteriorated. In order to be able to recognize the installation of such a manipulation device 28, the procedure according to a method now shown in connection with FIGS. 2 and 3 is followed:

In the method illustrated in FIGS. 2 and 3, it is monitored whether, outside of a planned injection of fuel by an injector 14, the corresponding actuator 16 is additionally actuated. For this purpose, after a start block 30 in a block 32 first that cylinder or combustion chamber 12a, 12b et cetera, selected in which a monitoring is to be performed. This selection is random and is effected by a random generator 34. In the present case, it is assumed that the combustion chamber 12a has been selected with the corresponding injector 14a and its actuator 16a.

In block 36, a normal scheduled main injection of fuel into the combustion chamber 12a is effected. For this purpose, the corresponding control parameters for the actuator 16 a determined by the control and regulating device 22 and output to this. To trigger them, the voltage applied to the actuator 16a is changed from a base value U ₀ to a control value U ₃₆ (initial control 36a), and at the end of the injection at time t _{36_END} , the charge of the actuator 16a is changed again by _resetting the corresponding voltage the level U _{0 is} returned (final control 36b).

Subsequently, a time interval dt is determined in a block 38. This is different from working cycle to working cycle of the combustion chamber 12 a and is also determined by means of a random generator 40. After the time interval dt has elapsed, a test initial activation 42a of the actuator 16a is performed in block 42. For this purpose, the actuator 16a is charged to a voltage level U ₄₂ , which is so low that it is ensured that the test drive in block 42 no injection of fuel through the injector 14a is effected in the combustion chamber 12a.

Independently of the test drives, the manipulation device 28 controls the actuator 16 a in such a way that after the main injection 36 an additional fuel injection MANIP is performed. The beginning of this injection MANIP_INI not planned by the actual control and regulation device 22 is at the time t _{MANIP_INI} after the beginning of the test start control 42a at the time t _{42_INI} , but still before the test end drive 42b.

In a block 44, the state quantity of the actuator 16a is detected as the state variable of the actuator 16a before the start of the test final control at the time t _{42_END} and compared with a limit value G. This is chosen so that when the voltage applied to the actuator 16 a voltage U is greater than the limit G, in any case can be assumed by a fuel injection. In the present embodiment, the current voltage U of the actuator 16a at time t _{42_END is} significantly greater than the limit value G and is in the range of the manipulated voltage U _MANIP .

If it is determined in block 46 that the current voltage U is greater than the limit value G, it can be assumed that the cause for this is a manipulated additional control of the actuator 16a, so that a corresponding measure can now be performed in block 48. For this purpose, an entry in a fault memory or even the decommissioning or blocking of the operation of the internal combustion engine 10 may include. In both initial cases of the block 46, a return occurs before the block 32.

FIGS. 2 and 3 illustrate the case in which the manipulation device 28 switches between a test initial activation 42a and a test end drive 42b wants to trigger an additional injection. FIG. 4 shows the case in which the control and regulation device 22 wishes to trigger a test initial activation 42a after the manipulation device 28 has triggered an additional activation MANIP of the actuator 16a. This case would also be detected in blocks 44 and 46, since the voltage U applied to the actuator 16a is detected before the start of the test initial control 42a. It should be noted that the piezoelectric actuator 16a is already charged (namely, by the manipulation device 28), which is recognized as an error. As in the embodiment of Figure 3 can be prevented by the random arrangement of the test drives 42 that the manipulation device 28 can predict the test drives 42 and perform appropriate deceptive measures.

FIG. 5 shows a further variant of the method. In this case is waived a test drive. Although the voltage applied to the actuator 16a voltage U is detected after the main injection 36, but this does not happen in connection with a test injection, but is of a time processing unit, in the control and regulating device 22 for the termination of the control of the actuator 16a is triggered by means of a trigger at time T _TRIG . The trigger is at a certain time interval dt at the beginning t _{36_END of} the final control 36b of the main injection 36. As has already been explained in connection with Figures 3 and 4, the time interval dt from injection to injection can be varied randomly by one As long as possible temporal range in which may be present triggered by the manipulation device 28 controls, and to deception by the To aggravate or prevent manipulation device 28.

By the trigger at time t _TRIG a measurement of the voltage applied to the actuator 16 a voltage U is started. If the measured voltage U _{TUN is} greater than the quiescent voltage U ₀ set by the control and regulating device 22, and in particular is so great that fuel is injected from the injector 14a into the combustion chamber 12a (this is the case when the measured voltage U _{TUN is} greater than a threshold value G), this is a sure indication of an additional manipulation caused by a manipulation device 28 and not planned by the control device 22. Also in this case, a measure is triggered, for example, the internal combustion engine 10 is turned off or there is an entry in a fault memory.

In all cases shown in FIGS. 3 to 5, the monitoring, ie the detection and evaluation of the voltage U applied to the actuator 16a, takes place only in such an angular range of the crankshaft 24, in that an additional control or injection MANIP could generate a torque.

Claims (11)

Method for operating an injector for an internal combustion engine (10), by means of which fuel can pass into a combustion chamber (12), in which the injector (14) is actuated with a signal (U) indicating the state of an actuator (16) of the injector (14), characterized in that outside of a planned injection (36) at least temporarily monitored (46), if the actuator (16) is additionally controlled, and that depending on the result of the monitoring (46) a measure is performed (48 ). A method according to claim 1, characterized in that at a time interval (dt) after a planned injection (36) at least one state variable (U) of the actuator (16) is detected, that the detected state variable is diagnosed (46), and that the Action (48) depends on the result of the diagnosis (46). A method according to claim 2, characterized in that the time interval (dt) is variable. A method according to claim 3, characterized in that the time interval (dt) is random. Method according to one of claims 2 to 4, characterized in that in an internal combustion engine (10) with a plurality of cylinders (12a, 12b) the state quantity (U) is detected at random at one or another cylinder (12a). Method according to one of claims 2 to 5, characterized in that at a time interval (dt) after a scheduled injection (36) a test drive (42) of the actuator (16) is performed, which does not cause or terminate injection, and that State variable (U) in connection with the test drive (42) is detected. Method according to one of the preceding claims, characterized in that it is checked in the monitoring (46) whether a state variable (U) reaches or exceeds a limit value (G). Method according to one of the preceding claims, characterized in that the monitoring (46) is performed within a working cycle only in such a crank angle or time range in which a torque can be generated by an injection (MANIP). Computer program, characterized in that it is programmed for use in a method according to one of the preceding claims. Electrical storage medium for a control and / or regulating device of an internal combustion engine, characterized in that a computer program for use in a method of claims 1 to 8 is stored on it. Control and / or regulating device for an internal combustion engine, characterized in that it is programmed for use in a method according to one of claims 1 to 8.

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