EP1730394B1 - Process for controlling and regulating an internal combustion engine - Google Patents

Abstract

In a process for controlling and regulating an internal combustion engine (1) having a common rail system, including individual accumulators (8), an injection end deviation and an injection beginning deviation are determined by comparison between the set and real values of the injection end and injection beginning. An injector (7) is then evaluated on the basis of these deviations, and the internal combustion engine is subsequently controlled and regulated on the basis of the injector evaluation.

Description

The invention relates to a method for controlling and regulating an internal combustion engine according to the preamble of claim 1.

In an internal combustion engine, the start of injection and the end of injection significantly determine the quality of the combustion and the composition of the exhaust gas. To comply with the legal limits, these two parameters are usually controlled by an electronic control unit. In practice occurs in an internal combustion engine with a common rail system, the problem that there is a time offset between the start of energization of the injector, the needle stroke of the injector and the actual injection start. The same applies to the end of injection.

From the DE 198 50 221 C1 is a test method for an injector known. In this, different operating points are determined for the injector by varying the pressure at the injector outlet with a constant inlet pressure. The injector is faultless if the operating points are within a permissible range of a test chart. The test method is used on an injector test bench. This is not usable if the injector is already installed in an internal combustion engine.

From the not previously published German patent application with the official file number DE 103 44 181.6 a method for controlling and regulating an internal combustion engine is known in which the injection end is detected from the pressure profile in a single memory of a common rail system. From the measured injection end is then a mathematical Function calculates a virtual injection start. However, changes in injector properties over its lifetime are not included in this procedure.

The object of the invention is for an internal combustion engine with a common rail injection system including individual storage as in DE 43 44 190 A1 to design a test method for the injector.

The object is solved by the features of claim 1. The advantageous embodiments are shown in the subclaims.

The invention provides a method for control and regulation in which an injection end deviation is calculated from a desired injection end and the measured actual injection end and an injection start deviation from a desired injection start and the virtual actual injection start is determined. Thereafter, an injector is evaluated based on the injection end deviation and the start of injection deviation and the further control and regulation of the internal combustion engine is based on the injector evaluation. In order to evaluate the injector, it is provided that an injection end tolerance band is selected and it is checked whether the injection end deviation lies within the injection end tolerance band. In addition, a start of injection tolerance band is selected and also checked whether the injection start deviation is within the tolerance band. The selection of the respective tolerance band as well as its limit values takes place as a function of the operating state of the internal combustion engine. The injector is then rated as error-free if the injection end deviation and the start of injection deviation lie within the respective tolerance band. Are these outside the respective Tolerance band, the injector is rated as faulty. Depending on the location of the start of injection deviation or injection end deviation to an evaluation threshold, it is then determined whether the injector is deactivated or the parameters of the injector, in particular energization start and energization duration are adjusted.

By means of the invention, the individual properties of the injectors can be determined over their lifetime. Based on the knowledge of these individual properties, the injectors can then be assimilated, i. H. their injection behavior is identical. The better knowledge of the injectors makes it possible to optimize their potential for use in terms of a reduction in consumption and emission reduction. For the maintenance of the internal combustion engine, this means that the maintenance intervals can be extended. In addition, a targeted diagnosis with maintenance suggestions for the service personnel can be issued.

Fig. 1

ein Systemschaubild;

Fig. 2

eine Injektor-Kennlinie;

Fig. 3

Druckverläufe;

Fig. 4

einen Programmablaufplan.

In the drawings, a preferred embodiment is shown. Show it:

Fig. 1

a system diagram;

Fig. 2

an injector characteristic;

Fig. 3

Pressure profiles;

Fig. 4

a program schedule.

The FIG. 1 shows a system diagram of an electronically controlled internal combustion engine 1. In the illustrated internal combustion engine 1, the fuel is injected via a common rail system comprising the following components: Pumps 3 with a suction throttle for conveying the fuel from a fuel tank 2, a rail 6, single memory. 8 and injectors 7 for injecting the fuel into the combustion chambers of the internal combustion engine 1. In this common rail system is the hydraulic resistance of the individual memory 8 and the supply lines adapted accordingly. For the invention it is immaterial whether the rail 6 comprises a storage volume or is designed only as a simple line.

The operation of the internal combustion engine 1 is controlled by an electronic control unit (ADEC) 4. The electronic control unit 4 includes the usual components of a microcomputer system, such as a microprocessor, I / O devices, buffers and memory devices (EEPROM, RAM). In the memory modules relevant for the operation of the internal combustion engine 1 operating data in maps / curves are applied. About this calculates the electronic control unit 4 from the input variables, the output variables. In FIG. 1 the following input variables are exemplarily shown: a rail pressure pCR, which is measured by means of a rail pressure sensor 5, a speed signal nMOT of the internal combustion engine 1, pressure signals pE (i) of the individual memory 8 and an input variable E. The input quantity E is, for example, the charge air pressure a turbocharger and the temperatures of the coolant / lubricant and the fuel subsumes.

In FIG. 1 are shown as outputs of the electronic control unit 4, a signal ADV for controlling the pump 3 with the suction throttle and an output size A. The output variable A is representative of the other control signals for controlling and regulating the internal combustion engine 1, for example, a current start BB and a current end BE.

In FIG. 2 an injector characteristic is shown. On the abscissa here is the energizing duration BD and plotted on the ordinate an injection qV. The injector characteristic curve is used to calculate a calculated injection quantity Energizing duration BD assigned. For example, the injection quantity qV (A) is assigned an operating point A and, correspondingly, the energizing duration BD (A). As dashed lines two limit lines are shown. The operating point A changes over the life of the injector. The causes for this are the magnetic changes of the magnetic circuit, the hydraulic changes, z. B. Change of the throttle cross-section, and the mechanical changes, eg. B. wear. The changes of the operating point A are indicated in the figure with corresponding arrows, resulting z. B. a new operating point A1.

In FIG. 3 For example, several pressure profiles are shown. The abscissa indicates the crankshaft angle Phi or the equivalent time. On the ordinate, the measured pressure pE (i) of a single memory is plotted. A desired spray course with the points A; B and C is shown as a solid line. As a dashed line with the points D, E and F, a first actual injection profile is shown. As a dot-dash line with the points A, G, H and J, a second actual injection profile is shown. A pre- and post-injection was omitted for reasons of clarity in the respective spray progressions. The reference character TBSB designates an injection start tolerance band with the limit values GW3 and GW4. The reference symbol TBSE determines an injection end tolerance band with the associated limit values GM1 and GW2. Also in the FIG. 3 Plotted is an ordinal parallel line, according to the evaluation threshold BWGW.

The process according to the invention proceeds as follows:

The electronic control unit outputs an energization start BB and a current end BE for the injector. This period corresponds to the energizing duration BD. From the pressure curve pE (i) of the individual memory, the actual injection end can be recognized without any doubt. For example, the pressure value pE (SE) includes the point E and the associated time value tE (dashed line). From this injection end, the associated virtual injection start can be calculated via a mathematical function, here the point D with the time value tD. Such a calculation method is known from the German patent application with the official file number DE 103 44 181.6 known. Their disclosure content is part of the disclosure of this application. Of course, it is also possible to determine the start of injection directly from the measured values of the individual storage pressure curve, without changing the essence of the invention. From the first actual injection profile, a time tSE (IST) is calculated from the current end BE to the measured end of injection, here time tE. For the start of injection, a time tSB (IST) is calculated from the start of energization BB until the virtual start of injection, time tD. After that, an injection end deviation dtSE is calculated from the desired injection profile and the first actual injection profile. This deviation corresponds to FIG. 3 the distance of the points E and B. For the start of injection also a start of injection deviation dtSB is calculated. This corresponds to the difference between the two points D and A.

As the next step, the injection end tolerance band TBSE is selected as a function of operating parameters of the internal combustion engine. Operating parameters of the internal combustion engine are to be understood as meaning the rail pressure, the speed of the internal combustion engine, the fuel temperature and the energizing duration BD. After selecting the tolerance band, it is checked whether the injection end deviation dtSE is within the two limit values GW1 and GW2 of the injection end tolerance band TBSE. In FIG. 3 this is the case with respect to the first actual injection run. Subsequently, the injection start tolerance band TBSB is selected and it is checked whether the start of injection deviation dtSB lies within the tolerance band with the limit values GW3 and GW4. In FIG. 3 the injection start deviation dtSB (points A, D) is also within the associated tolerance band. Since both the injection end deviation dtSE and the start of injection deviation dtSB lie within the respective tolerance band, the injector is rated as error-free.

In the second actual injection course (dot-dash line) both the injection end (point H, time tH) and the start of injection (point G) are outside the respective tolerance band. Next, it is checked whether the injection end is larger than a judgment threshold BWGW. In FIG. 3 the point H is within the evaluation threshold BWGW. As a consequence of this check, a diagnostic entry is created, which provides that the injector should be exchanged at the next maintenance date. Thereafter, the control parameters of the injector, in particular energization start and energization duration are adjusted.

In the FIG. 4 a program flowchart of the method is shown as a subroutine. The FIG. 4 consists of subfigures 4A and 4B. The subroutine can be both time-controlled and event-driven, if z. B. a high exhaust gas temperature dispersion is detected. At S1 it is checked whether a stationary operating state exists. A stationary operating condition is z. B. at a constant speed. If it is determined at S1 that there is an unsteady state, a corresponding waiting loop is run through with S2. Is the query included? S1 positive, an injector to be evaluated is selected at S3. At S4, a mode MOD is selected. The operating mode is specified by the operator. In an operating mode MOD1, the pre- and post-injection is deactivated for the evaluation of the injector, step S5. Thereafter, at S6, the energization start BB is retarded in the sense of smaller crankshaft angles before top dead center. In addition, the energizing duration BD is adjusted. In an operating mode MOD2, the injector including the pre, main and post injection is evaluated. At S7 the injection end SE is detected. From the injection end SE and the current end BE, a time tSE (IST) is calculated. At S9, a virtual injection start SBv is determined from the injection end SE. Following this, a time tSB (IST) is determined at S10 from the start of energization BB and the virtual start of injection SBV. At S11, an injection start deviation dtSB and an injection end deviation dtSE are calculated from the respective target / actual comparison.

Depending on operating parameters of the internal combustion engine, the injection end tolerance band TBSE and the start of injection tolerance band TBSB are calculated at S12. At S13, it is checked whether the injection start deviation dtSB is within the tolerance band. If this is not the case, the program sequence continues at point B. If the test at S13 shows that the start of injection deviation dtSB lies within the start of injection tolerance band TBSB with the limit values GW1 and GW2, then it is checked at S15 whether the end of injection deviation dtSE is within the injection end tolerance band TBSE with the limit values GW3 and GW4 lies. If both the injection start deviation and the spraying deviation are within the respective tolerance band, the injector is rated as error-free at S14 and the subroutine is ended.

If the test at S15 indicates that the injection end deviation is outside the tolerance band, then it is checked in S16 whether the start of injection deviation dtSB or the end of injection deviation dtSE is greater than the evaluation limit value BWGW. If this is the case, a diagnostic entry is initiated at S19 and the corresponding injector is deactivated at S20. Alternatively it can be provided that instead of deactivating the injector, the internal combustion engine is stopped. Thereafter, the program schedule for this case is completed. If the check at S16 shows that the injection end deviation and the start of injection deviation are smaller than the assessment limit value BWGW, a diagnosis entry is initiated at S17. The diagnostics entry recommends that the service technician replace the injector at the next maintenance date. Then, at S18, the control parameters of the injector are adjusted and the subroutine is ended.

reference numeral

1

Internal combustion engine

2

Fuel tank

3

pump

4

electronic control unit (ADEC)

5

Rail pressure sensor

6

Rail

7

injector

8th

Single memory

Claims (11)

1. Method for controlling and regulating an internal combustion engine (1) having a common rail system including individual accumulators (8), in which method an actual end of injection (SE(IST)) is detected from the pressure profile (pE(i), i = 1,2 ... n) of the individual accumulators (8), and a virtual actual start of injection (SBv(IST)) is determined,
   characterized
   in that an end of injection deviation (dtSE) is calculated from a setpoint end of injection (SE(SL)) and the actual end of injection (SE(IST)), a start of injection deviation (dtSB) is calculated from a setpoint start of injection (SB(SL)) and the virtual actual start of injection (SBv(IST)), an injector (7) is evaluated on the basis of the end of injection deviation (dtSE) and the start of injection deviation (dtSB), and the further control and regulation of the internal combustion engine (1) takes place on the basis of the injector evaluation.
2. Method according to Claim 1,
   characterized
   in that an end of injection tolerance band (TBSE) is selected and it is checked whether the end of injection deviation (dtSE) lies within the end of injection tolerance band (TBSE).
3. Method according to Claim 1,
   characterized
   in that a start of injection tolerance band (TBSB) is selected and it is checked whether the start of injection deviation (dtSB) lies within the start of injection tolerance band (TBSB).
4. Method according to Claims 2 and 3, characterized
   in that the injector (7) is evaluated as being free of faults if the end of injection deviation (dtSE) and the start of injection deviation (dtSB) lie within the respective tolerance band (TBSE, TBSB).
5. Method according to Claim 2 or 3, characterized
   in that the injector (7) is evaluated as being faulty if the end of injection deviation (dtSE) lies outside the end of injection tolerance band (TBSE) or the start of injection deviation (dtSB) lies outside the start of injection tolerance band (TBSB).
6. Method according to Claim 5,
   characterized
   in that, in the case of an injector (7) evaluated as being faulty, it is checked whether the end of injection deviation (dtSE) or the start of injection deviation (dtSB) are greater than an evaluation limit value (BWGW) and, depending on the comparison, either the control parameters of the injector (7) are adapted (dtSE < BWGW; dtSB < BWGW) or the injector (7) is deactivated (dtSE > BWGW; dtSB > BWGW) or the internal combustion engine (1) is deactivated.
7. Method according to Claim 6,
   characterized
   in that the control parameters of the injector (7) are adapted for every pre-injection, main injection and post-injection and/or multiple injection.
8. Method according to Claim 6,
   characterized
   in that a diagnostic entry is additionally made.
9. Method according to one of the preceding claims, characterized
   in that the evaluation of the injector (7) is carried out under steady-state operating conditions of the internal combustion engine (1).
10. Method according to Claim 9,
    characterized
    in that, for the evaluation of the injector (7), pre-injections and post-injections are deactivated.
11. Method according to Claim 10,
    characterized
    in that, in the event of deactivation, the control parameters of the injector (7), in particular a start of energization and a duration of energization, are adapted.

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