EP1809884B1 - Device and method for correction of the injection behaviour of an injector - Google Patents

Description

The invention relates to an apparatus and a method for correcting the injection behavior of at least one injector with a device for storing information about the at least one injector and means for controlling the at least one injector taking into account the stored information, the information being obtained by comparing desired injection quantities be determined with actual injection quantities individually at several test points of the at least one injector and are based.

State of the art

A generic device and a method for correcting the injection behavior of at least one injector, in which the information is correction quantities for a quantity correction field of the injector, starts from DE 102 15 610 A1 out. In the case of these devices and methods known to the Applicant also as IMA (individual quantity balancing), the control duration in relation to a nominal characteristic map 210 (cf. Fig. 2 ) corrected so as to come as close as possible to a desired target amount. In this case, four test values from the production, for example the injection quantity at four different test points, are stored in the control unit during installation per injector, for example. From these variables, a correction quantity map 220 (see FIG Fig. 2 ) as a function of the desired amount and the fuel pressure. Basically, this map is a quantity error map. In the controller is then given Rail pressure to a target injection quantity with the quantity error map calculated a corrected quantity requirement. From this in turn, a drive time is then determined with the inverted nominal characteristic map 210 of the injector. An example of such a quantity correction at one of the test points is based on Fig. 3 described, which is assumed to be error-free measurements. During the injector test, an amount q _{P, is} measured for the activation time t _P , which deviates by Δq from the nominal quantity q _{P, soll} . During operation of the injector, therefore, a quantity requirement q _{P, is} to be reduced by Δq to q _mod , over the normal characteristic results from this a drive time t _corr . If the real and the nominal characteristic curve run parallel, the injection of the quantity q _{P is to be} effected by the injector controlled with a control duration t _corr . If, on the other hand, both characteristic curves do not run parallel, the resulting injection quantity q _{corr is} not equal to the quantity requirement, although the injector was tested at the relevant point.

From the DE 102 32 356 A1 has become known a method for quantity correction due to pressure signals, with the aid of an injector drift can be corrected. For this purpose, in at least one operating point of the internal combustion engine, the start of injection and the end of injection are compared with values of the injection start, preferably stored in an individual map of the injector and the end of injection of this operating point, corrected in a deviation of injection start and / or injection duration so that the deviation disappears and the correction values are stored.

Such devices and methods are used in particular in electrically operated injectors for the injection of diesel fuel, for example in the context of so-called common rail systems for use. In the "common rail" accumulator injection, pressure generation and injection are decoupled. The injection pressure is generated independently of the engine speed and the injection quantity and is ready for injection in the so-called "rail". The injection timing and the injection amount are calculated in the electronic engine control unit and implemented by an injector on each engine cylinder via a remote-controlled valve.

In the method described above is now problematic that first the quantity requirement is corrected and then only the injector characteristic is used. It is assumed that the slope of the injector characteristic in the environment of the considered operating point is constant and coincides with the slope of the nominal characteristic. However, these are very simplistic assumptions that do not apply in many parts of the work area and therefore affect the accuracy of the process.

Advantages of the invention

In contrast, the invention offers the advantage of making the injector-specific quantity adjustment directly on the level of the activation duration. As a result, the precision of the injected fuel quantities is significantly increased. In particular, it is not necessary to assume a constant characteristic gradient in the vicinity of the test points, as is the case with the above-described method known from the prior art. In addition, neither a coincidence of the slope of the nominal and the real characteristic nor a known form of the injection curve must be assumed. It is also a great advantage that the transmission of the control duration correction determined for individual test points to the entire desired pressure quantity characteristic map is easier than for a quantity error characteristic map. This significantly improves the accuracy of the individual set balance and extends the applicability of the method to larger classes of problems.

Preferred embodiments and embodiments of the method and the device according to the invention are the subject of the subclaims.

Thus, the means for controlling the injectors are preferably integrated in an engine control unit. The injector-specific control with the associated correction is performed by the engine control unit.

The means for storing the information at the injector are, for example, a data memory attached to the injector, resistors arranged on the injector, barcodes arranged on the injector or, for example, a labeling field, also alphanumeric encryption detected by a camera is possible.

A preferred embodiment provides, as a device for storing information, a semiconductor integrated circuit arranged on the injector. Such a semiconductor integrated circuit can be integrated, for example, in the head of the injector. The data used by the controller is preferably stored in the semiconductor integrated circuit in a nonvolatile memory.

The engine control unit also preferably has a semiconductor integrated circuit with which the information stored in integrated semiconductor circuits of the injectors is processed so as to achieve injector-specific control.

drawing

Fig. 1

eine schematische Darstellung eines Teils eines aus dem Stand der Technik bekannten Common-Rail-Systems;

Fig. 2

die Korrektur über dem Mengenfehler gemäß einem aus dem Stand der Technik bekannten Verfahren;

Fig. 3

schematisch die Auswirkung einer Steigungsabweichung bei der aus dem Stand der Technik bekannten Korrektur über dem Mengenfehler an einem Prüfpunkt;

Fig. 4

die erfindungsgemäße Mengenkorrektur mittels Änderung der Ansteuerdauer und

Fig. 5

schematisch die Bestimmung eines Kennlinienabschnitts sowie der korrigierten Ansteuerdauer gemäß dem erfindungsgemäßen Verfahren.

Further advantages and features of the invention are the subject of the following description and the drawings of exemplary embodiments. Show it:

Fig. 1

a schematic representation of part of a known from the prior art common rail system;

Fig. 2

the correction over the quantity error according to a method known from the prior art;

Fig. 3

schematically the effect of a slope deviation in the known from the prior art correction over the quantity error at a test point;

Fig. 4

the quantity correction according to the invention by means of changing the drive time and

Fig. 5

schematically the determination of a characteristic section and the corrected drive time according to the inventive method.

Description of the embodiments

In Fig. 1 is the high pressure part of the known from the prior art storage injection system common rail shown. In the following, only the main components and those components which are essential for the understanding of the present invention will be explained in more detail. The arrangement comprises a high pressure pump 10, which communicates via a high pressure line 12 with the high pressure accumulator ("rail") 14 in connection. The high pressure accumulator 14 is connected via further high pressure lines to the injectors. In the present illustration, a high pressure line 16 and an injector 18 are shown. The injector 18 is part of an engine of a motor vehicle. The illustrated System is controlled by a motor controller 20. In particular, control of the injector 18 takes place by the engine control unit 20.

On or in the injector 18, a device 22 is provided for storing information which relates individually to the injector 18. The information stored in the device 22 may be taken into account by the engine controller 20 so that individual control of each injector 18 may occur. The information can be correction values for the quantity map of the injector 18, which at the beginning in connection with FIGS. 2 and 3 be determined manner described. The device 22 for storing the information can be implemented as a data memory, as one or more electrical resistors, as a barcode, by alphanumeric encryption or else by a semiconductor integrated circuit arranged on or in the injector 18. The engine control unit 20 may also comprise a semiconductor integrated circuit for evaluating the information stored in the device 22.

The system according to the invention and the method according to the invention are described below in connection with 4 and FIG. 5 explained in more detail.

On the fully assembled injector 18, a section of the characteristic curves "quantity over actuation period" is measured for several test points. In order not to extend the test time or only slightly, the procedure is as follows. To smooth the stroke-to-hub scattering at a test point, a certain number, for example 50, of directly consecutive injections with different drive times are carried out in an area to be determined suitably (sweep). Since these quantities - as mentioned - are subject to a stroke-to-hub scattering, the data points a smoothing regression curve is placed, which now represents a section of the injector for the given rail pressure, as shown schematically in Fig. 4 is shown. By means of this characteristic curve, it is possible to determine for the respective test point the actuation duration correction tp-t _korr , which _is necessary for achieving the desired injection quantity q _{P, soll} . As a result, apart from measuring errors, an exact quantity correction is possible in principle at the test point. Optionally, an extrapolation of the characteristic section can also take place in this step.

The number and selection of the test points to be measured in this way must be determined with regard to the required precision of the actuation duration correction and other boundary conditions. The range over which the actuation time is changed during the measurements depends on the maximum expected actuation duration correction per test point.

For each injector 18, the information about the measurement results of the control period correction must be recorded so that it is available later during installation of the injector 18 when installed in the engine, if necessary. This is done by the means 22 for storing the information.

In the control unit 20, the information about the actuation period correction is used at various test points of the injector 18 in order to calculate a actuation duration correction over the entire setpoint rail pressure range. This happens as in the calculation of the quantity error map in the case of the prior art, for example the DE 102 15 610 A1 known and referred to as IMA method. In the control unit is from setpoint and rail pressure by means of a nominal map 410 (see FIG. Fig. 5 ) determines the nominal actuation time t _nom . In parallel, a drive duration correction Δt is determined in the above-described manner in a circuit unit 420. The sum of the two values t _nom and Δt results in the activation duration t _corr .

Claims (11)

1. Apparatus for correcting the injection behaviour of at least one injector (18), having a device (22) for storing information from the at least one injector (18) and means for controlling the at least one injector (18) by taking account of the stored information, wherein the information has been ascertained and obtained by comparing setpoint injection quantities with actual injection quantities individually at a plurality of checkpoints for the at least one injector (18), characterized in that the means for controlling the at least one injector by taking account of the stored information comprise: means for determining a nominal family of characteristic curves (410), in which the nominal actuation period (t_nom) is determined from the setpoint injection quantity and the rail pressure, and a circuit unit (420) for determining an actuation period correction (Δt) on the basis of a number of directly successive injections with different actuation periods that are performed at a checkpoint and placement of a regression curve, representing an injector characteristic, through the data points and use of said regression curve to determine the actuation period correction which is required for achieving the setpoint injection quantity.
2. Apparatus according to Claim 1, characterized in that the means for controlling the at least one injector (18) are integrated in an engine controller (20).
3. Apparatus according to Claim 1, characterized in that the device (22) for storing information is a data memory which is mounted on or in the injector (18).
4. Apparatus according to Claim 1, characterized in that the device (22) for storing information is implemented by a bar code arranged on the injector (18) or by a data matrix or by resistors arranged on the injector (18).
5. Apparatus according to Claim 1, characterized in that the device (22) for storing information is implemented by alphanumeric encryption or plain text on a label field of the injector (18).
6. Apparatus according to Claim 1, characterized in that the device (22) for storing information is an integrated semiconductor circuit arranged on or in the injector (18).
7. Apparatus according to one of the preceding claims, characterized in that the comparison of setpoint injection quantities with actual injection quantities ascertains the information to be stored, in that the engine controller (20) takes the stored information and calculates the individual actuation period correction family of characteristic curves for the at least one injector (18), and in that the injection quantity and/or the injection point are corrected in accordance with the actuation period families of characteristic curves.
8. Apparatus according to one of the preceding claims, characterized in that the engine controller (20) has an integrated semiconductor circuit.
9. Method for correcting the injection behaviour of at least one injector (18) having the following method steps:

   - the at least one injector (18) is controlled by taking account of stored information, wherein the information has been ascertained and obtained by comparing setpoint injection quantities with actual injection quantities individually at a plurality of checkpoints for the at least one injector (18),

   characterized in that

   - at each checkpoint for the at least one injector (18) a section of an injection quantity actuation period characteristic is determined by a plurality of measurements using a varying actuation period,

   - the measurement points place a smoothing regression curve,

   - this regression curve is taken as a basis for determining at a checkpoint an actuation period correction (Δt=t_p-t_corr) which is required for achieving a setpoint injection quantity (q_p,setpoint).
10. Method according to Claim 9, characterized in that a stroke-to-stroke variation is smoothed by performing a particular number of directly successive injections with different actuation periods at a checkpoint in a prescribable range.
11. Method according to Claim 10, characterized in that 50 directly successive injections with different actuation periods are performed in the prescribable range.

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