DE102004030992B4 - Method and device for controlling an internal combustion engine with a camshaft adjusting system - Google Patents

Abstract

The invention relates to a method and a device for controlling an internal combustion engine with a camshaft adjusting system, which adjusts at least one camshaft in an angular position on the basis of nominal values, and with a monitoring means which compares an actual value of the angular position with the desired value and deviations which exceed a threshold value detects an error, wherein a test means is provided, which transmits an error value to the camshaft adjusting system instead of the desired value, wherein the camshaft adjusting system adjusts the angular position of the at least one camshaft based on the error value, wherein the error value provided by the test means is such that the Monitoring means detects an error when comparing setpoint and actual value.

Description

State of the art

The invention is based on a method and a device for controlling an internal combustion engine a camshaft adjusting system, wherein a target value of an angular position is compared with an actual value of the angular position.

From the US Pat. No. 6,257,184 B1 a variable valve timing mechanism is known, which changes an opening timing of an intake valve and / or an exhaust valve in a vehicle engine using oil pressure to change the rotational phase of a camshaft with respect to a crankshaft, wherein a delay time in accordance with the engine speed, the cooling water temperature and the amplitude of a change in the target rotational phase is determined, and a fault diagnosis, which is performed by comparing the target rotational phase and the actual rotational phase.

The DE 197 41 086 A1 discloses a method for monitoring the setting of a control element, wherein at least in response to a setpoint an actuating element in the sense of approaching an actual value is influenced to the target value, wherein for monitoring the deviation of a value representing the set value of a value representing the actual value with a predetermined limit is compared, this limit value is given on the basis of the change of the setpoint.

Variable valve timing by camshaft adjustment of an internal combustion engine, for example, from the articles "dance of the valves" and "variable valve timing" of the magazine "mot professional special variable valve control", no. 3/2002, United Motor-Verlag, Stuttgart, known.

The camshaft adjustment allows a mechanical variation of the valve actuation times at the inlet and outlet channel of a cylinder chamber. The required adjustment of the camshaft in the direction of early or late, for example, via a Flügelzellenversteller or the like by oil pressure. The control of the oil pressure in the individual chambers is done by solenoid valves, which are addressed via a pulse width modulated signal, starting from the control unit. The camshaft must reach the setpoint with sufficient accuracy within a certain time. If this is not the case, then it is a mistake. Malpositions during the variable camshaft adjustment lead inter alia to a deterioration in the exhaust gas by a no longer optimal combustion to combustion misfires. Furthermore, the driver will complain about a lack of torque or lack of power and losses in smoothness, such as jerking, which occur due to faulty camshaft positions and thus resulting filling differences between the cylinder banks.

The diagnosis of the camshaft control is currently done by checking the camshaft adjustment angles. For this purpose, the difference between setpoint and actual value is compared with applicable threshold values. If the threshold values for a period to be applied are exceeded or not reached, the camshaft adjustment unit is set. An adjustment error of the camshaft is always set if, after the debounce time has elapsed, the actual angular position is outside an admissible tolerance band.

From the not pre-published DE 103 40 819 a method for monitoring a camshaft adjustment of an internal combustion engine is known in which a target value of an angular position is compared with an actual value of the angular position, wherein a differentiated fault diagnosis is achieved ereicht that at least two types of errors can be detected based on the course of the actual value over time. Two possible error types are, for example, a "slow response" error or a "target error". A "slow response" error is detected when, despite an observed angular change, the camshaft phasing system has failed to reach a setpoint or range within a predetermined time.

A "target error" is detected if the actual value does not leave a certain tolerance range at all, i. the camshaft is stuck.

This error detection ensures that a malfunction of the camshaft adjustment and / or mechanical errors can be quickly detected and reported to the driver, for example. However, the possible errors not only affect the performance of the internal combustion engine, but also worsen the quality of the exhaust gas by the erroneous operation of the gas exchange valves.

For exhaust-influencing system units, which also includes the variable camshaft adjustment, many countries require by law to functionally monitor these system units. In particular, it is sometimes required to diagnose more than one possible type of error.

In the simplest case, it may be provided to check the fault monitoring, incorporate faulty components that affect the functionality of the camshaft adjustment in the vehicle, and to test whether the fault monitoring detects an error.

To generate errors, for example, the flow rate of the oil pump could be throttled; Vane wheel, solenoid or solenoid valve with leaks or clogged valves are used; or oil pressure or oil viscosity.

Advantages of the invention

The device according to the invention with the features of the independent claim has the advantage that the device controls an internal combustion engine with a camshaft adjusting system, wherein the control unit adjusted by reference values at least one camshaft in an angular position, and that a monitoring means, the an actual value of the angular position with the A reference value is compared and, in the case of deviations exceeding a threshold value, an error is detected, further comprising a test means which transmits an error value to the camshaft adjusting system instead of the nominal value and the camshaft adjusting system adjusts the angular position of the at least one camshaft on the basis of the error value The test means provided error value is such that the monitoring means detects an error when comparing setpoint and actual value.

Accordingly, an advantageous method for controlling an internal combustion engine with a camshaft adjusting system is derived, in which at least one camshaft is adjusted by means of nominal values and an adjusting actual value of an angular position of at least one camshaft is monitored, wherein the actual value is compared with a desired value and in the case of deviations exceed a threshold value, an error is detected, wherein for error simulation the camshaft adjustment system instead of the setpoint set an error value, and that the camshaft adjustment system based on this error value at least one camshaft adjusted, and that the error value is such that the deviation of the self-adjusting actual value in comparison with the setpoint exceeds the threshold and an error is detected.

The method according to the invention and the device according to the invention thus advantageously check the functionality of a monitoring means or of the monitoring method, without the need for complex interventions on the internal combustion engine and units. Furthermore, it is possible to perform this check outside of service or repair times and, for example, to automate and perform at given intervals by a control unit independently.

The measures listed in the dependent claims advantageous refinements and improvements of the independent claims device and method are possible.

It is particularly advantageous to form the error value as a function of the desired value. It is thus possible to generate the error values starting from the desired values, for example with the aid of special algorithms. In particular, for example, the smallest but erroneous setpoint-actual value deviations can be generated, as is not necessarily possible due to the "global" error value, which generates errors virtually under all circumstances in the case of a target-actual comparison.

A further advantage results if the actual values are set by predetermining different error values in such a way that different types of errors are determined. Thus, it is possible not only a basic response of the monitoring, but very specifically to check the detection of different types of errors.

According to a further advantageous embodiment, it is provided that the fault simulation takes place or is started based on a coding of the setpoint. Thus, it is advantageously possible to maintain the functionality of the fault simulation permanently, preferably in a control unit, the functionality being hidden in daily use on the basis of the setpoint coding. However, as soon as the generated setpoint values are coded, for example by an application device or the control unit itself, the fault simulation becomes active.

According to a further advantageous embodiment, it is provided that different fault simulations for different types of errors are initiated on the basis of the coding. This has the advantage that it does not have to be communicated through expensive additional data lines a control device and in particular a test agent in the control unit, which type of error type to be tested. Thus, it is possible in a simple manner, already provide the setpoint based on the coding this information, so that all other process steps or control components can respond accordingly.

According to a further advantageous embodiment, it is provided that the error value is formed starting from the desired value with the aid of a filter. Thus, it is possible in an advantageous manner, for example, to simulate too slow response of the camshaft adjustment and to generate a corresponding error.

According to a further advantageous embodiment, it is provided that different types of errors are simulated by changing parameters of the filter. Thus, it is particularly possible to simulate a different response behavior of the camshaft adjustment by varying, for example, time constants. In extreme cases, the time constant can be chosen very large, so that the camshaft does not adjust.

list of figures

Other features, applications and advantages of the invention will become apparent from the following description of embodiments of the invention, which are illustrated in the drawings. All described or illustrated features, alone or in any combination form the subject of the invention, regardless of their combination in the claims or their dependency and regardless of their formulation or representation in the description or in the drawings.

• 1 zeigt schematisch den Ablauf von Sollwertvorgabe bis zu den jeweiligen Istwerten;
• 2 zeigt schematisch ein erfindungsgemäßes Verfahren;
• 3 zeigt schematisch eine erfindungsgemäße Vorrichtung.

Show it:

• 1 schematically shows the sequence of setpoint input to the respective actual values;
• 2 schematically shows a method according to the invention;
• 3 schematically shows a device according to the invention.

description

The invention is based on the consideration to check an error monitoring system for proper functioning by simulating typical errors preferably by an electronic intervention in the control and are not actually caused by complex mechanical interventions in units and components of the internal combustion engine.

According to the invention, the fault simulation on a camshaft adjusting system essentially requires the interaction of the following functionalities: a) setpoint specification, b) camshaft position controller or camshaft adjusting system or also actuator, c) camshaft diagnosis or monitoring means.

The setpoint specification of the camshaft angle positions offers the option of not giving a setpoint that changes stepwise directly to the actuator or camshaft position controller via a setpoint change limitation. This change limitation is always designed vehicle-specific or individually for an internal combustion engine and bedatet.

Thus, the setpoint specification specifies positions and rate of change of the position change. An error-free functioning camshaft adjustment system, for example, where there is no "slow response" behavior and no "target error" behavior, is always able to follow this position change sufficiently quickly and accurately.

This is not the case with a faulty camshaft adjusting system. So that a faulty actuator does not have to be installed in the vehicle to check the fault, a faulty actuator is simulated via setpoint filtering within the position controller.

The camshaft diagnosis determined from the originally specified setpoint course and the simulated via the position controller slow actual position curve for a defective camshaft divider corresponding misalignments in the form of setpoint / actual value differences.

In 1 the sequence for the adjustment of a camshaft adjusting system is shown schematically. Starting from, for example, operating conditions of the internal combustion engine or driver wishes becomes a setpoint specification 10 generated. As described a sudden setpoint specification 10 can not be tracked by mechanical actuators typically, a setpoint is via a setpoint change limit 20 generated, which can be followed quickly and accurately by a perfectly functioning camshaft adjustment system. With numeral 30 is the actual value or the time profile of the angular position, which is at a camshaft when driven with the setpoint 20 adjusts. The signal chain via setpoint specification 10 , Setpoint 20 and actual value 30 thus represents the normal operating case. The actual value 30 is typically at the setpoint 20 compared and signaled an error in impermissible deviations or initiated an error response.

To verify this monitoring agent is a test agent 40 provided, in the present embodiment, starting from the desired value 20 an error value 50 forms, wherein the camshaft adjustment system instead of the setpoint 20 with the error value 50 is controlled so that a corresponding actual value 60 established.

However, the monitoring means still compares the found actual value with the original setpoint value 20 , To check the monitoring means is the error value 50 formed so that the deviation determined in the target / actual comparison is so large that the monitoring means detects an error.

2 schematically shows a possible procedure according to the invention. The upper input arrow symbolizes the incoming setpoint specification, which is limited by a setpoint limitation to a setpoint value 20 in step 120 leads. In a subsequent query step 125 It is checked whether a normal operation or a test operation or a fault simulation is present. In normal operation, the setpoint 20 in step 130 unchanged to the camshaft adjusting system in step 170 transfer. The adjustment of the camshaft is in step 160 monitored and an actual value 30 . 60 the angular position of the camshaft to the step 180 transfer. In the monitoring step 180 the actual value 30, 60 is out of the step 160 with the setpoint 20 out of step 120 compared. Depending on the size of the deviations either a faultless operation or a faulty adjustment of the camshaft is reported to a subsequent process step on.

Will in the query step 125 determined that a test operation or a fault simulation is present, step 140 Simulation initiated. In step 140 an error value 50 is formed which in step 150 to the camshaft adjusting system in step 170 is transmitted. The adjustment of the camshaft is in step 160 monitored and an actual value 30 . 60 the angular position of the camshaft to the step 180 transfer. In the monitoring step 180 becomes the actual value 30 . 60 out of step 160 with the setpoint 20 out of step 120 compared.

Will the simulated error in step 180 recognized, at least for this detected error is a perfectly functioning monitoring means 180 in front. Depending on the application and test case, all relevant error types can now be checked successively by repeating the simulation loop.

3 schematically shows a device according to the invention 1 for controlling an internal combustion engine 400 with a camshaft adjustment system 300 , The dashed frame symbolizes the entire functionality of a control unit 1 , Within the framework, means for carrying out the method according to the invention are shown schematically. Analogous to the steps described above 120 and 125 is in the control unit 1 a means or module 200 arranged, symbolized by the input arrow a setpoint specification 10 or a setpoint 20 detected and in normal operation the setpoint 20 to a camshaft adjusting system 300 transmits or during a fault simulation or test operation this setpoint 20 to a test agent 240 as well as additionally, independently of the present operating case, the setpoint 20 a monitoring device 280 provides.

Is in the module 200 a test mode is detected, the setpoint 20 no longer to the camshaft adjustment system 300 forwarded. In the test medium 240 becomes an error value 50 formed, and in the subsequent module 250 is used instead of the setpoint 20 the error value 50 to the camshaft adjusting system 300 forwarded. Symbolic are in 3 outside the controller 1 a camshaft adjusting system 300 in conjunction with an internal combustion engine 400 shown. From the actually adjusting by the control angle position on at least one camshaft is in the module 260 an actual value 30, 60 is determined and sent to the monitoring means 280 forwarded. The monitoring device 280 checks the deviation of the determined actual value 30 . 60 from the desired setpoint 20 In the case of excessively large deviations which, for example, exceed a certain threshold value, an error reaction is initiated in the subsequent process steps or modules. In the case of a fault simulation or a test operation, it is checked in the following modules whether the type of error actually tested by the monitoring means 280 was detected. If necessary, further steps, for example further fault simulations, are initiated.

A fault simulation can be initiated via a codeword according to a possible embodiment. With the help of the code word, for example, the setpoint module 200 and / or the test agent 240 addressed directly and a fault simulation are initiated.

In a preferred variant, the desired value or already the desired value specification is coded or provided with a codeword, so that all subsequent steps and modules can recognize on the basis of the coding whether a normal operation or test operation is present.

Furthermore, in a preferred embodiment, the test agent 240 or the module 250 be designed as a filter. Thus, a "sluggish" reaction of a camshaft adjusting system can be simulated in a simple manner and a "slow response" error can be provoked in the monitoring means.

If the time constant of the filter, which realizes the setpoint filtering at the input of the position controller, is set to the maximum possible value, the simulation in conjunction with a manual setpoint specification can also be used for a "Target Error" error case at any position of the possible adjustment range.

Furthermore, the method according to the invention makes it possible to carry out an exhaust gas-relevant design of the camshaft diagnosis or of the monitoring means.

The camshaft diagnosis evaluates the setpoint during this time 20 the setpoint specification 10 including setpoint change limitation and the actual value that is set.

Due to the self-adjusting differences between the setpoint and the actual value, the diagnosis has the option of detecting a number of "x" errors. The value which is set at "x" as soon as the permissible exhaust gas quantity is exceeded, can be adopted as a design of the rating until the "malfunction identification lamp" in the instrument cluster can be controlled.

This makes it possible to obtain an exhaust gas-relevant design as a function of the number of detected "slow response" fault events.

Claims (9)

Device (1) for controlling an internal combustion engine (400) with a camshaft adjusting system (300) which adjusts at least one camshaft in angular position on the basis of nominal values (20), with a monitoring means (180) having an actual value (30, 60) of the angular position compares with the setpoint (20) and detects an error in the case of deviations which exceed a threshold, characterized in that a test means (240) is provided which transmits an error value (50) to the camshaft adjusting system (300) instead of the setpoint (20). transmits that the camshaft phasing system (300) adjusts the angular position of the at least one camshaft based on the error value (50), that the error value (15) provided by the test means (240) is such that the monitoring means (240) compares the desired value and actual value (20, 30, 60) detects an error. Method for controlling an internal combustion engine (400) with a camshaft adjusting system (300), wherein at least one camshaft is adjusted on the basis of nominal values (20) and an actual value (30, 60) of an angular position of the camshaft is monitored, wherein the actual value (30, 60) are compared with a setpoint value (20) and an error is detected in the event of deviations exceeding a threshold value, characterized in that an error value (50) is given to the camshaft adjusting system (300) instead of the setpoint value (20) for error simulation, and that the Camshaft adjustment system (300) based on this error value (50) at least one camshaft adjusted, and that the error value (50) is such that the deviation of the self-adjusting actual value (50) compared with the target value (20) exceeds the threshold and detected an error becomes. Method according to Claim 2 , characterized in that the error value (50) is formed as a function of the desired value (20). Method according to Claim 2 or 3 , characterized in that by setting different error values (50) different actual values (30, 60) are set and thus different errors are simulated. Method according to at least one of the preceding Claims 2 to 4 , characterized in that a fault simulation based on a coding of the setpoint (20). Method according to at least one of the preceding Claims 2 to 5 , characterized in that based on the coding different fault simulations for different types of errors are initiated. Method according to at least one of the preceding Claims 2 to 6 , characterized in that the error value (50) is formed starting from the first set value (20) by means of a filter. Method according to at least one of the preceding Claims 2 to 7 , characterized in that different types of errors are simulated by changing parameters of the filter. Device after Claim 1 , characterized in that it is for use in one of the methods Claim 1 to 8th is designed.

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