DE102004049747A1 - Method for operating of fuel injection system has output value of I-controller accepted in pilot performance characteristic with frequency accepted in frequency characteristic for corresponding operating point - Google Patents

Abstract

The method is for the operating of a fuel injection system (10) which has a fuel accumulator (13), the actual pressure in which is influenced by an integral action controller (24). The output value of the I-controller is accepted in a pilot performance characteristic (27), and in a frequency characteristic (35) for the corresponding operating point is entered the number of how often an output value is accepted in the pilot performance characteristic, and this number is compared with a first threshold value (SW1). The output value of the I-controller is compared with a second threshold value (SW2) as long as the number is greater than or the same as the first threshold value. Independent claims are also included for the following: (A) a computer programme which is programmed for use in the proposed method; (B) an electrical memory medium for a control unit, whereby the aforesaid computer programme is stored in the memory medium; (C) a control unit for a fuel injection system of especially a motor vehicle; and (D) a fuel injection system with a control unit designed for use in the aforesaid method.

Description

The The invention is based on a method for operating a fuel injection system in particular of a motor vehicle according to the preamble of the claim 1. The invention also relates to a corresponding computer program, a corresponding electrical memory, a corresponding control device and a corresponding fuel injection system, in particular for a motor vehicle.

at known fuel injection systems is a fuel storage provided to the fuel over a metering unit and a high-pressure pump is supplied. It continues known, the actual pressure in the fuel storage with, inter alia Help influence an I-controller.

Farther it is known, sudden Leakage, for example, by appropriate monitoring to recognize the pressure in the fuel injection system.

Especially In high-pressure fuel injection systems, the individual components of the same have production-related variations. This requires a pressure monitor on possible Leaks a rather big one Allow fluctuation range of the pressure, so not already such Manufacturing-related differences erroneously as leakage be recognized.

Task and Advantages of the invention

task The invention is a method for operating a fuel injection system to create, even with production-related dispersals safe and quick detection of a leak in the fuel injection system guaranteed is.

These Task is in accordance with the invention in a method of the type mentioned the features of the characterizing part of claim 1 solved. The The object is also achieved by the subject matter of claims 5 to 8 solved.

According to the invention Output value of the I-controller transferred to a pilot control map. simultaneously is in a frequency map for the corresponding operating point the number entered, how often in the pilot control map has been taken over an output value. These Number is compared to a first threshold. The initial value of the I-controller is compared with a second threshold, if the number greater or is equal to the first threshold.

By the frequency map is detected, whether already a learning process at a certain operating point the fuel injection system has taken place, and whether so already the associated one Output value of the I-controller transferred to the pilot control map has been. Only in this case is an error detection. Because only in this case may the output value of the I-controller itself be no longer significantly different from zero. This results from that by the learning process, in particular production-related deviations different fuel injection systems already by the pilot control map are balanced. The I-controller should at least not so far produce significant output values more.

Has So already a learning process of the pilot control map took place, so an error detection is possible. Dodges in this case, the output of the I-controller is substantially zero off, it may turn out to be a sudden Leakage or the like can be closed.

By the inventive method is thus achieved that, for example, a leakage of the fuel injection system safe and fast is detected, regardless of whether the fuel injection system subject to manufacturing dispersion or not.

at An advantageous development of the invention are the values the pilot control map during operation of the fuel injection system gradually determined and entered in the pilot control map and with every entry in the pilot control map, it is the one in the frequency map included number for increases the corresponding operating point. This ultimately represents the Learning process of the pilot control map, where at the same time the number of the learning processes in the frequency map is stored.

at An advantageous development of the invention is in operation the fuel injection system for the current operating point of the associated pilot value from the Pre-control map read out. This stands for the compensation of production-related Deviations required pre-tax value immediately available. The production-related deviations do not need to help be compensated for the I-controller.

Embodiments of the invention

Other features, application possibilities th and advantages of the invention will become apparent from the following description of embodiments of the invention, which are illustrated in the figures of the drawing. All described or illustrated features, alone or in any combination form the subject matter of the invention, regardless of their summary in the claims or their dependency and regardless of their formulation or representation in the description or in the drawing.

1 shows a schematic block diagram of an embodiment of a method according to the invention for operating a fuel injection system, and 2 shows a section of a pilot map, which in the method of 1 is used.

In the 1 is a fuel injection system 10 an internal combustion engine shown. At the fuel injection system 10 it is in particular a high-pressure fuel injection system and the internal combustion engine may in particular be a diesel internal combustion engine for a motor vehicle.

The fuel injection system 10 has a pump 11 , In particular, a high-pressure pump on which the fuel via a metering unit 12 is supplied. The pump 11 is the output side with a fuel tank 13 connected, in which the fuel is stored under pressure. In a manner not shown is the fuel storage 13 connected to injection valves, via which the fuel is injected into combustion chambers of the internal combustion engine. Furthermore, the fuel storage 13 a pressure sensor 14 associated with the pressure in the fuel tank 13 is measured.

The fuel injection system 10 is controlled and / or regulated by a control unit, not shown. For this purpose, the control unit has a computer with an electrical storage medium, in particular with a flash memory. On the storage medium, a computer program is stored, which is executable on the computer. This computer program is suitable for the fuel injection system 10 to influence and thus perform the desired control and / or regulation.

In addition to the fuel injection system 10 is in the 1 also a procedure 20 to operate this fuel injection system 10 represented in the form of a block diagram. This method 20 is executed by the controller. If necessary, parts of the process 20 also be realized with the help of analog electronic modules.

From the pressure sensor 14 becomes an actual pressure ID in the fuel tank 13 generates corresponding signal and to a comparator 21 given. There, the actual pressure ID is compared with a target pressure SD. The differential pressure DD is passed on to three controllers, namely to a P-controller 22 (Proportional controller), a D-controller 23 (Differential controller) and to an I-controller 24 (Integral controller). The outputs of these three controllers are from an adder 25 to a control value DS for a desired fuel flow. This desired fuel flow is then intended by the metering unit 12 the pump 11 and thus the fuel storage 13 be supplied.

Furthermore, a pre-control signal V1 is provided, which via an adder 26 is added to the control value DS.

Furthermore, there is a pilot control map 27 provided, the output-side pilot signal V2 via an adder 28 is added to the control value DS for the fuel flow. As input signals are the pilot control map 27 the actual injection quantity q and the current speed n are supplied.

The control value DS for the desired fuel flow becomes a characteristic 29 fed to the metering unit 12 represents. With the help of this characteristic 29 is determined from the control value DS that control value SS for a current with which the metering unit 12 must be controlled to produce the desired fuel flow.

This control value SS represents a setpoint for a downstream current controller 30 dar. Of this current regulator 30 then becomes the metering unit 12 supplied with the control value SS corresponding current. The actually about the metering unit 12 flowing electricity is from a sensor 31 , in particular a measuring resistor, measured and as an actual value IW to a comparator 32 given. There, the actual value IW is subtracted from the control value SS. The difference then acts on the current regulator 30 ,

In the in the 1 illustrated method 20 will be in the fuel tank 13 existing actual pressure ID regulated to the target pressure SD. These are. including the three controls 22 . 23 . 24 and the pilot signals V1, V2 provided. Depending on the resulting control value DS for the desired fuel flow then the metering unit 12 affected. The metering unit 12 acting current is thereby from the current controller 30 regulated.

In particular, in high-pressure fuel injection systems subject to, among other things, the Zu Measuring units of various fuel injection systems of a production-related dispersion. This means that the metering unit of a first fuel injection system, for example, a different efficiency and thus a different characteristic than the metering unit of a second fuel injection system. The same applies to the pumps and fuel storage of different fuel injection systems. Overall, this can lead to significant deviations in terms of the metering of fuel through the different fuel injection systems.

These production-related deviations of the components of the fuel injection system 10 be through the pilot control map 27 and the resulting pilot signal V2 considered. With the help of the pilot control map 27 In this case, an adaptive precontrol is realized.

After the production of the fuel injection system 10 are in the pilot control map 27 contain no values. From the pilot control map 27 so that only the value zero can be read out. The pilot control map 27 has no influence on the procedure at this time 20 for operating the fuel injection system 10 ,

The pilot control map 27 is in operation of the fuel injection system 10 gradually filled with values. This will determine if the fuel injection system 10 currently located in a stationary operating point. If this is the case, then for this operating point, the associated output value of the I-controller 24 in addition to the already explained method 20 further processed as explained below. This operating point-dependent output value of the I-controller 24 is in the 1 marked with the reference Ix.

In the 2 is a section of the pilot control map 27 of the 1 shown. On the two axes of this pilot control map 27 the injection quantity q is plotted against the speed n.

In the section of the 2 are four nodes M11, M12, M21, M22 of the pilot control map 27 characterized. The first interpolation point M11 belongs to an injection quantity q1 at a rotational speed n1, the second interpolation point M12 to an injection quantity q2 at the rotational speed n1, the third interpolation point M21 to the injection quantity q1 at the rotational speed n2 and the fourth interpolation point M22 to the injection quantity q2 at the Speed n2.

Furthermore, in the section of the 2 the instantaneous steady-state operating point Mx of the fuel injection system 10 shown. This operating point belongs to the current injection quantity qx and the current speed nx. The instantaneous operating point Mx is arranged within the rectangle spanned by the four support points M11, M12, M21, M22 and thus adjacent to all four support points M11, M12, M21, M22.

The current operating point Mx of the fuel injection system 10 does not agree with any of the interpolation points M11, M12, M21, M22 of the pilot control map 27 match. The output value Ix of the I-controller belonging to this operating point Mx 24 is therefore distributed to the four interpolation points M11, M12, M21, M22. This is done for each of the nodes M11, M12, M21, M22 using the following equations: M11, new = M11, old + Ix · (n2 - nx) 2 · (Q2 - qx) 2 M12, new = M12, old + Ix · (n2 - nx) 2 · (Q1 - qx) 2 M21, new = M21, old + Ix · (n1 - nx) 2 · (Q2 - qx) 2 M22, new = M22, old + Ix · (n1 - nx) 2 · (Q1 - qx) 2 ,

With these equations, the closest support point is always more strongly influenced, while the other three support points are less affected. If the instantaneous operating point Mx falls into one of the interpolation points M11, M12, M21, M22, the associated output value Ix of the I-controller becomes 24 only taken into account at this interpolation point, but not at the other three interpolation points.

It is understood that other equations may be provided for the calculation of the values in the interpolation points. In particular, there is also a differently weighted distribution of the output value Ix of the I-controller 24 on optionally more than four nodes of the pilot control map 27 possible.

In this way, in the pilot control map 27 for a plurality of other operating points gradually during operation of the fuel injection system 10 Output values of the I-controller 24 stored at the support points. This constitutes a "learning" of the pilot control map 27 during operation of the fuel injection system 10 represents.

At the same time during operation of the fuel injection system 10 in the pilot control map 27 stored values and read as pre-control values V2 in the process 20 of the 1 used.

When reading from the pilot control map 27 again, the reference points are taken into account, but in reverse order. The support points arranged adjacent to the instantaneous operating point are determined. After that The values stored at these four interpolation points are taken from the pilot control map 27 read. These four values are linked to the precontrol value V2 via a predetermined function, in particular a linear interpolation. In this interpolation, the arrangement of the current operating point with respect to the four adjacent nodes is taken into account.

Thus, the I-controller is known 24 for a certain operating point qx / nx, that is to say for a specific injection quantity qx at a specific rotational speed nx on the output side, an output value Ix, this output value Ix becomes the pilot control map 27 accepted. Takes the fuel injection system 10 at a later time again this operating point gx / nx, so supplies the pilot control map 27 Immediately those pre-control value V2, in which the associated output value Ix is taken into account.

The I-controller 24 provides, inter alia, an output value Ix if and only if one or more components of the fuel injection system 10 have production-related deviations. For example, indicates the metering unit 12 due to production-related variations on an actual characteristic, which of the per se intended characteristic curve 29 the metering unit 12 deviates, then this deviation from the I-controller 24 compensated by a corresponding output value Ix. Through the explained assumption of such output values in the pilot control map 27 then gradually all deviations of the characteristic of the metering unit 12 no longer through the I-controller 24 balanced, but by the pilot value V2 of the pilot control map 27 ,

The advantage of this procedure is, inter alia, that the readout of the pilot control values V2 from the pilot control map 27 can be done much faster than the generation of a corresponding output value by the I-controller 24 , This results from the I-controller 24 inherent inertia with which he always approaches his initial values over a time constant. Based on the pilot control map 27 must the I-controller 24 at least with regard to production-related deviations of the components of the fuel injection system 10 no longer deliver an output signal.

In a change between two operating points is thus by the pilot control map 27 a production-related deviation of components of the fuel injection system 10 Considered much faster than just by the I-controller 24 it is possible. The accuracy of the fuel injection is thus determined by the method 20 for operating the fuel injection system 10 elevated.

Additionally, in the process 20 of the 1 a frequency map 35 provided, like the pilot control map 27 over the injection quantity q and the speed n is clamped. Ir this frequency map 35 is entered for the individual interpolation points, as often in the pilot control map 27 for the same nodes from an output value Ix of the I-controller 24 derived value has been accepted.

Thus, for a given injection quantity qx and a specific rotational speed nx, an output value Ix is entered into the four adjacent reference points of the pilot control map 27 taken over, so is at the same time in the frequency map 35 increased the number of such takeovers for the corresponding support points. The increase is made according to the same function, as in connection with the pilot control map 27 has already been explained. If, for example, a certain interpolation point of the pilot control map 27 hit directly, so in the frequency map 35 existing number increased by one. This occurs at the pilot control map 27 a distribution to the four adjacent nodes, so is the frequency map 35 the increase by one in the same way distributed to these four adjacent support points.

The frequency map 35 is thus comparable to the pilot control map 27 gradually filled with numbers for each support points.

Furthermore, in the process 20 of the 1 a comparator 36 provided by the frequency map 35 is controlled. The comparator 36 performs a comparison, and that is in the frequency map 35 number stored for an operating point is compared with a first threshold value SW1. By way of example, the threshold value SW1 may be the number "2". It is understood that a different number than threshold SW1 can be selected.

If then for the current operating point in the frequency map 35 stored number is smaller than the number "2", then becomes a subsequent comparator 37 switched off. If the in the frequency map 35 stored number is greater than or equal to the number "2", then the subsequent comparator 37 switched on.

Is the comparator 37 switched off, no further action is taken. Error detection is not possible.

Is the comparator 37 however, it is switched on by the comparator 37 the output value Ix of the I-controller 24 with a second threshold SW2 compared. This second threshold value SW2 is selected such that an output value Ix which is approximately equal to zero or at least does not differ substantially from zero is accepted as correct.

Results from the comparator 37 However, if the comparison made is that the output value Ix differs substantially from zero, ie that the output value Ix is either substantially greater or substantially smaller than zero, then an error is made. In this case, the comparator 37 generates an error signal F and further processed in a manner not further explained.

With the method explained above 20 it is possible, for example, a sudden leakage in one of the components of the fuel injection system 10 to recognize. In this case, the I-controller tries 24 the desired target pressure SD in the fuel tank 13 despite the leakage upright. This has the consequence that the output value Ix of the I-controller 24 changed a lot. The leakage thus leads to a strong deviation of the output value Ix of the I-controller 24 from zero. This strong deviation is from the comparator 37 recognized as an error.

The frequency map 35 serves to make the comparator 37 only becomes active if that of the I-controller 24 for a certain operating point generated output value Ix previously in the pilot control map 27 has been taken over. Because only in this case, the output value Ix of the I-controller 24 by the precontrol value V2 of the pilot control map 27 replaced, with the result that after that the output value Ix of the I-controller 24 in itself should not deviate significantly from zero. This stems from the fact that changes in the components of the fuel injection system 10 are already taken into account by the pilot control value V2 and the I-controller 24 so far no longer needs to compensate.

Through the frequency map 35 Thus, it is ensured that production-related variations between different fuel injection systems of the comparator 37 not erroneously recognized as leakage. The threshold SW1 and the comparator 3b serve to ensure that for the current operating point in each case a learning process of the pilot control map 27 took place. As a result of this measure, a value stored in the pilot control map is only considered correct if the number of learning processes corresponds at least to the first threshold value SW1. Only then is it assumed that the value stored in the pilot control map is largely correct and thus the I regulator 24 in itself only one output value Ix for this operating point may deliver, which differs only insignificantly from zero.

Similarly, changes in the components of the fuel injection system 10 due to signs of aging. These changes also lead to strong changes in the output value Ix of the I-controller 24 , in turn, from the comparator 37 be recognized as a mistake.

Claims (8)

Procedure ( 20 ) for operating a fuel injection system ( 10 ) in particular of a motor vehicle, wherein the fuel injection system ( 10 ) a fuel storage ( 13 ), the fuel via a metering unit ( 12 ) is fed, in which an actual pressure (ID) in the fuel storage ( 13 ) among others by an I-controller ( 24 ) and in which the I-controller ( 24 ) generates an output value (Ix) for a specific operating point, characterized in that the output value (Ix) of the I-controller ( 24 ) in a pilot control map ( 27 ), that in a frequency map ( 35 ) is entered for the corresponding operating point, the number of times in the pilot control map ( 27 ) an output value (Ix) has been adopted, that this number is compared with a first threshold value (SW1), and that the output value (Ix) of the I-controller ( 24 ) is compared with a second threshold value (SW2) if the number is greater than or equal to the first threshold value (SW1). Procedure ( 20 ) according to claim 1, characterized in that the values of the pilot control map ( 27 ) during operation of the fuel injection system ( 10 ) and gradually into the pilot control map ( 27 ) and that for each entry in the pilot control map ( 27 ) in the frequency map ( 35 ) is increased for the corresponding operating point. Method according to one of the preceding claims, characterized in that during operation of the fuel injection system ( 10 ) for the current operating point of the same pilot value (V2) from the pilot control map ( 27 ) is read out. Method according to Claim 6, characterized in that the actual pressure (ID) in the fuel reservoir (ID) 13 ) from that from the pilot control map ( 27 ) pre-control value (V2) is influenced. Computer program, characterized in that it for use in a method according to one of claims 1 to 4 is programmed. Electrical storage medium for a control unit, characterized in that on the Spei chermedium a computer program is stored, which is programmed for use in a method according to one of claims 1 to 4. control unit for one Fuel injection system, in particular a motor vehicle, characterized characterized in that it is for use in a method according to a the claims 1 to 4 is prepared. Fuel injection system, in particular for a motor vehicle with a control unit that for use in a method according to any one of claims 1 to 4 is prepared.