DE102007010496A1 - Method for comparative examination of injection combustion engines, particularly vehicle engines, involves controlling engine of electronic motor control, and providing fuel injector with multiple independently controllable modules - Google Patents

Abstract

The method involves controlling an engine of an electronic motor control, and providing a fuel injector (40) with multiple independently controllable modules. Multiple test sequences are bring together for a test matrix, in which all operating mode of these modules pass through. An independent claim is also included for an arrangement for the execution of the examining method.

Description

State of the art

at modern internal combustion engines are electronically controlled Engine management systems used a variety of metrics for controlling the motors. It will be after set control and regulation algorithms for optimization the engine characteristics, control variables for Fuel injection, idle control determined and to control used corresponding actuators.

1 shows the basic structure of such an engine management system using the example of a motor control for a spark-ignition engine:
The engine control unit records the operating parameters of the engine via internal and external measuring elements. These operating parameters may be accelerator pedal position, engine speed, intake air temperature, exhaust gas, lubricants and coolants, chemical composition of the exhaust gas, pressures, etc. These operating parameters are detected via inputs shown here by way of example up to the control unit. The control unit processes these values in accordance with specified programs and settings and controls the engine ignition via the ignition coil and spark plug ignition shown here as a schematic diagram and via the injection port with switch and solenoid valve. In addition, these engine control units are usually provided with a diagnostic interface to which an external diagnostic device can be connected via a connecting cable. In addition to self-diagnosis functions and fault memories, which will not be described in more detail here, such engine control units can contain additional functions which, in conjunction with the external diagnostic unit, permit checking of the mechanical condition of the engine without complicated mechanical assembly work.

DE 198 59 004 A1 describes such a diagnostic function:
By switching off individual cylinders or by disabling ignition and / or injection for that particular cylinder, the power contribution of each individual cylinder can be determined. The test cycle envisages shutting down each cylinder of a multi-cylinder engine sequentially and determining the effects of this shutdown on - depending on the test procedure - speed, run-up time, injection quantity or exhaust gas composition. A comparison of the effects of engine operation without the respective cylinder allows conclusions about the mechanical condition (tightness) of the respective cylinder.

For this controls the diagnostic device via diagnostic cable and Diagnostic connection to the engine control unit and causes switching off individual cylinders. At the same time is the diagnostic device enables the corresponding from the engine control unit Results: z. B. Change in engine speed, change the injection quantity, run-up times, etc. to retrieve and more To provide evaluations.

When Testing and evaluation procedures are several alternatives known by selective shutdown of individual cylinders at least a qualitative statement about the contribution to performance of each individual cylinder enable.

It can z. B. on comparative speed measurement, in the Injection and ignition parameters of the remaining cylinders kept constant, the performance contribution of each individual cylinder be determined qualitatively. Also a comparison measurement at constant Regulated speed is conceivable, in which the additional Injection amount of the remaining cylinder is determined, the required is to turn off the cylinder to be tested the Keep the speed constant. Another alternative is a startup test in combination with cylinder deactivation conceivable in which the engine with exactly reproducible settings for injection and ignition accelerated to a desired speed is and the time to reach this target speed as a comparison is used.

As in DE 198 59 004 A1 continue running, are thus conclusions about mechanical inadequacies in the engine, such. B. leaks on pistons, head gaskets or valves without complex mechanical compression measurements possible.

at modern diesel engines with direct fuel injection in the Combustion chamber are used to improve exhaust quality, engine torque and Fuel consumption ever higher injection pressures sought. Furthermore, it is of considerable importance that the Combustion chamber injected fuel quantity is correct to the exhaust quality observed. This has led to the development of fuel injectors, in which a hydraulic pressure booster is integrated. This pressure booster is controlled separately and allowed the increase of the injection pressure over the supply pressure -Relativruck- of the fuel injector.

The independent control of the pressure intensifier allowed the operation of the injector both with an injection pressure to supply pressure level (System pressure), as well as at the higher pressure level, the provided by the pressure intensifier.

The previously known diagnostic programs, as described above, may indicate signs of malfunction of the entire injector However, a more sophisticated analysis of the cause of the error is not possible.

Disclosure of the invention:

The previously known test cycles provide for a test run, in which all the cylinders of a multi-cylinder engine are switched off individually one after the other and the effects of this shutdown on - depending on the test method - speed, acceleration time, injection quantity or exhaust gas composition is determined. The results of such a test cycle, in which, for example, the achieved speed (final speed) of the engine is evaluated when one cylinder is switched off as a result of the test, are shown in FIG 3 shown. Assuming that the mechanical properties (tightness, compression) of the cylinders are not very different, conclusions can be drawn about the properties of the fuel injectors.

core This invention is, in engines whose fuel injectors more Separately controllable individual systems (modules) include the motors in a test matrix to check out the multiple test sequences consists. These test sequences differ from those described above test cycles described by the technique in that the successive Shutdowns of the respective injector and thus the corresponding Cylinders in all intended operating modes of the participating modules be performed.

contains z. For example, a fuel injector, a pressure booster module and an injection module, which is controlled independently can each be a test sequence with and to perform a test sequence without pressure booster module. The According to the invention executed test matrix then consists of at least these two test sequences. It is to realize that the shutdown of a cylinder only in the pressure-boosted Operation produces a significantly different result.

Contain the fuel injectors a greater number independently controllable modules, is correspondingly a larger one Number of test sequences required. The test matrix expands accordingly.

Thereby creates a result matrix in which each cylinder in each mode the modules of the fuel injectors has been switched off once. Should If a module is faulty, all tests with the power off or ineffective faulty module significant deviations in results on, since with all other tests the faulty module in each case with was in use. The results of this invention carried out Test program can thus conclusions on the Function of all independently controllable modules of all fuel injectors Motors too.

alternative are also test sequences conceivable in which instead of the shutdown the cylinder, one after the other only the independently controllable Module of the fuel injector of the respective cylinder turned off and compare the effects of these between the cylinders Module shutdown on the characteristic values of the tests for the identification of defective ones Module is used.

Brief description of the drawings:

Based In the drawings, the invention will be described below in more detail.

It shows:

1 in the basic structure of an engine management system for a spark-ignited internal combustion engine,

2 in the basic structure of a test arrangement for a self-igniting internal combustion engine with direct fuel injection,

3 the representation of a test cycle according to the prior art,

4 the comparison of two test sequences according to the invention carried out test procedures and

5 the representation of a test cycle with two test sequences using the inventively proposed test arrangement.

embodiments

in the Following is the embodiment of the invention by way of example on a test sequence for a four-cylinder engine without spark ignition (Diesel engine) with direct fuel injection.

The basic structure of the test arrangement including motor control is in 2 exemplified: An engine control unit 4 is via a diagnostic interface 3 and a diagnostic cable 2 to an external diagnostic device 1 connected. The engine control unit 4 is responsible for controlling the motor in normal and test mode while the diagnostic device 1 the control data required for the diagnosis to the engine control unit 4 sends, controls the test procedures and then the test results from the engine control unit 4 retrieves.

The data required to control the engine is collected by the engine control unit 4 via exemplified sensor inputs 12 to 16 and calculates accordingly from that in the engine control unit 4 specified algorithms required for controlling the motor control variables.

The motor is controlled via outputs 9 . 17 and 19 of the engine control unit 4 , Here is an example of the control of a fuel injector 40 with injection module 30 and pressure booster module 20 represented for a cylinder.

The activation of the injection module 30 via a control output 9 of the engine control unit 4 that has a switch 10 a solenoid valve 31 controls. Through the solenoid valve 31 hydraulically becomes a nozzle needle 34 pressed, the injectors 32 opens or closes. Opening time and opening time of the injectors are essential control parameters of the engine. The opening period essentially determines the injected fuel quantity. This in turn affects engine output and torque output.

Furthermore, in 2 the control of a pressure booster module 20 shown. About exit 17 operates the engine control unit 4 a switch 18 that has a solenoid valve 21 the pressure amplifier 20 hydraulically activates. By opening the solenoid valve 21 for unpressurized return 23 can be a working piston 24 of the pressure booster 20 according to the area ratio of the booster 20 the injection pressure 33 opposite to the supply pressure 22 of the injector (system pressure).

The pressure booster module 20 is independent of the injection module 30 controllable, so that the injection module 30 depending on the control of the pressure booster 20 both at supply pressure level 22 - System pressure level - as well as on the higher pressure level of the pressure intensifier 20 can be operated. The injection pressure of the injector significantly affects the power and torque output as well as the exhaust quality of the engine.

The here indicated outputs 19 of the engine control unit 4 represent the control outputs for the remaining cylinders of a four-cylinder engine and are identical to output 9 and exit 17 executed.

Description of the test procedure

In the diagram 3 a test cycle according to the prior art is exemplified for a run-up test, in which the final speed reached is evaluated as the test criterion for a four-cylinder engine. Accordingly, four starts are initiated, in which one cylinder is deactivated in each case. For each acceleration phase, the same setpoint quantity is specified as the injection quantity for a fixed period of time. At the end of the period, the achieved engine speed is recorded and evaluated. The example in 3 shows at shutdown of the third cylinder ➂ that despite the same target amount, a higher final speed is achieved than when passing through each other deactivated cylinder. This means that the injector to cylinder 3 despite an identical target quantity, the quantity is too small, because the test run without a cylinder 3 leads to a better engine acceleration and thus to a higher final speed.

The diagrams in 4 The results of the test matrix shown by way of example consist of the results of two test sequences S1 and S2, since in the example illustrated the fuel injectors 40 from two independently controllable modules - injection module 30 and pressure booster module 20 - are constructed. The test sequence S1 denotes a test sequence for operation of the fuel injector 40 without pressure amplifier module 20 , the test sequence S2 represents such for the operation of the fuel injector 40 with activated pressure booster module 20 ,

For test sequence S1, the pressure intensifiers are 20 deactivated, the injection takes place at rail pressure level 22 and hiding the control of the injection modules 30 worried the shutdown of the respective cylinder. The diagram shows no significant differences between the cylinders. This means that with pressure booster switched off 20 no quantity errors occur.

Test sequence S ² is in pressure-boosted operation, ie with activated pressure amplifiers 20 hazards. The test sequence S2 in 4 shows a significantly higher final speed with deactivated cylinder ➂. The evaluation of the test matrix shows that the pressure booster 20 in the fuel injector 40 of the cylinder 3 must be faulty.

It are performed by the invention Test according to test matrix conclusions about more accurate error localization possible.

This implies. Traversing the test matrix for the in 2 exemplified injection system has a higher final speed in both test sequences S1 and S2 upon deactivation of a particular cylinder, as in 5 shown on a defective nozzle module 30 of the corresponding cylinder. Such an injector would z. B. for a repair in the workshop (field repair) in question, whereas the in 4 illustrated case of a speed Increase only in pressure-boosted operation to a defective pressure booster module 20 indicates what precludes injector repair.

The Test matrix can both be constructed so that the test sequences from test runs for all operating modes of the modules exist in each case a deactivated cylinder, as well Each test sequence in each operating mode passes through all the cylinders and the other test sequences the other modes of operation of the modules system checked.

The Target injection quantities can be used for injection at system pressure level different from the nominal injection quantities be selected in pressure-boosted operation.

It is also conceivable, with other test methods than the example here described run-up test with fixed preset set the test matrix build. Thus, test methods are conceivable in which a given Injection quantity is injected until a predetermined engine speed is reached. Evaluation criterion is then the time until the Reaching this preset reference speed needed becomes.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 19859004 A1 [0003, 0007]

Claims (10)

Method for comparative testing of injection combustion engines, in particular motor vehicle engines, in which the engine is controlled by an electronic engine control, which is provided with self-diagnosis means and / or with a connection interface for an external diagnostic device ( 3 ) is equipped, on the / can be obtained from the measured and displayable deviations of the respectively defined parameters when switching off each cylinder information that can conclude a possible target deviation of this cylinder, characterized in that in fuel injectors, the more independently controllable modules include combining several test sequences into a test matrix in which all operating modes of these modules are traversed. Method according to claim 1, characterized in that that the tests of a test sequence are defined to be a malfunction a module to a significant deviation of the measurement result between Test Sequences (S2) with Activation and Test Sequences (S1) with Deactivation this module leads. Method according to Claims 1 and 2, characterized the test sequences (S1 and S2) of a test matrix are defined in this way are that the evaluation of the test matrix a unique identification faulty module allows. Method according to Claims 1 to 3, characterized that between the individual test sequences (S1 and S2) of a test matrix certain parameters kept constant within a test sequence can be changed. Method according to one of the preceding claims, characterized in that the diagnostic function of the engine control unit ( 4 ) / external diagnostic device ( 1 ) is programmed so that the respective engine control variables of the test sequence (injection quantity per cylinder and stroke, number of injections or reference speed, injection time, in spark-ignited engines compliance with specified ignition parameters such as ignition timing and ignition angle, etc.) specified and the test sequences by controlling the modules and by sequential shutdown of the cylinders are performed according to the predetermined test procedure in the context of the proposed test matrix. Method according to one of the preceding claims, characterized in that the self-diagnosis function of the engine control unit ( 4 ) or via the diagnostic interface ( 3 ) connected external diagnostic device ( 1 ) is programmed so that it outputs the results of the selected test criteria after passing through the intended test sequences of a test matrix. Method according to one of the preceding claims, characterized characterized in that the evaluated measured variables Engine speeds, accelerations, times until reaching defined Criteria, operating characteristics of the ignition system, chemical or physical properties of the exhaust gas or control variables the emission control system can be. Method according to one of the preceding claims, characterized characterized in that it is in the program code of the diagnostic device (Self-diagnosis function of the engine control unit or external Diagnostic device) is realized. Arrangement for carrying out the test method according to one of the preceding claims, characterized in that a correspondingly programmed diagnostic device ( 1 ) via a connection interface ( 3 ) of a suitably programmed engine control ( 4 ) and that the execution of the test procedures is performed by the test device ( 1 ) is introductory and startable. Arrangement for carrying out the test method according to claim 9, characterized in that a correspondingly programmed diagnostic device ( 1 ) via a connection interface ( 3 ) of a suitably programmed engine control ( 4 ) and that measurement results of the test procedures from the test device ( 1 ) are readable and displayable.