EP1533505A2 - Method and apparatus for diagnosing failures in a control device for a vehicle combustion engine - Google Patents

Abstract

The fault diagnosis process is used on a control device (5) for an internal combustion engine (14). When the fault symptom (1) develops, the reason to the fault is reported, and the diagnosis manager (3) normally switches off the faulty control device completely or initiate is an emergency function. All the information on faults is listed. The detected fault is compared with the stored fault pictures so that the limitation of the control function can be kept to a minimum.

Description

The invention is based on a method or of a device for fault diagnosis in control devices an internal combustion engine of a motor vehicle, which the Operability of sensors, actuators and / or system functions monitor and detect a fault symptom determine the actual cause of the error that occurred according to the species of the independent claims 1 and 10. It It is already known that a LIH manager the functions of Control devices, for example by activating an emergency function (LIH function, limp home function) limited or in the worst case, the affected control devices just turn off. This maximum error response of the controllers is initiated because the actual Cause for the error symptom is unknown.

Furthermore, it is known that in diagnostic procedures error symptoms summarized similar detection methods. These methods have a diagnostic trouble code that specified in the ISO standard.

From DE 199 41 440 A1 a method for controlled Operation of a device, in particular an internal combustion engine known to be diagnosed with trouble symptoms. Due to the error symptoms can cross influences of consequential errors arise, resulting in a high complexity of the real System diagnostics of operating or control functions leading to difficult analysis. In the lateral interference test On the one hand, hard or control restriction requirements and rated. On the other hand, the operating or Control restriction requirements filtered so that no Opposites occur. After the cross interference test is a bundle of individual measures or in combination approved with several measures, respectively the severity of their intervention in the operation of the device are. For evaluation and evaluation of the individual errors the electrical diagnosis and the functional diagnosis becomes proposed a matrix method. To a scheduling too create, the matrices of the matrix are multiplied. The Scheduling takes into account a temporal prioritization as well as the cross influences of the diagnosed errors in such a way that the device with a maximum possible Performance can be operated.

Another fault diagnosis procedure is from the DE 197 23 097 C1. Here are the mutual direct Dependencies of the monitored operating functions in a matrix with a "1" or in the absence of dependence entered with a "0". For dependent errors creates a so-called dilemma or deadlock, the an indication that there are two supervised error functions cause a mutual dependence. Thereby are Subsequent errors distinguishable from normal errors. Is it possible, the interdependence of the two error functions break up, the causative error can be determined. This process is called validation.

The invention is based on the object, a method or to provide a device in which the analysis an occurring error symptom can be simplified so that an underlying error is uniquely identified can be. This task comes with the characteristics of the sibling Claims 1 and 10 solved.

In the method according to the invention for fault diagnosis in Control devices of an internal combustion engine of a motor vehicle or the device with the characterizing Features of the independent claims 1 and 10 results the advantage that the functional processes because of the methodological Process can be made simpler and clearer, because the error (s) will be recognized exactly. As special It is considered advantageous that the structure of the previous control devices can be simplified because their functional limitations are graded and with minimal Impact can be formed. Another advantage is also seen in the fact that the error tests performed modular can be because the function to be restricted separately can be validated and deadlocks are detected. Especially can have mutual regulatory restrictions and Mutual dependencies of the defect images specifically tested become. So far, because of the branching of secondary reactions complex validation procedures are performed. With the subject invention, however, this is no longer necessary, as defined runflat reactions with convergent Function control reaction can be used. Advantageous is further that by branching of the secondary reactions the Convert system restrictions. Also can be retrofitted advantageously new system requirements for fault detection, required by customers or lawmakers be introduced via an appropriate interface. Another advantage is that safety-relevant Error symptoms can trigger direct error reactions. Also new safety concepts can be applied more easily.

In practice, the handling of the fault diagnosis is clearer become. Error simulation programs can be modular be created, with parameters dependent cross-connections the emergency running reactions as well in the simulation with can be included. The cycle of emergency system reactions can be tested, especially since a Synchronous detection of multiple error images is possible.

Further advantageous potentials are also included, for example seen that a simple extension to other vehicle concepts is given and that the error information by external control devices, especially in the service workshop can be read out and used.

By the measures listed in the dependent claims are advantageous developments and improvements of the method or the device given. As special advantageous appears the possibility, in addition to the original error symptom also such further information to capture and save due to the error response the control device have arisen. For example, you can by influencing the engine control more Consequential errors occur. On the other hand, certain consequential errors can occur also be excluded.

To ensure a good overview, the error symptoms advantageously listed in the form of a table and saved.

By accurately diagnosing an actual error results itself an easy way to the resulting error to respond with a customized optimal error response. In particular, this can be achieved that the performance the control device in dependence on the Severity or weighting of the error is so affected that overall for the operation of the internal combustion engine, For example, a diesel or gasoline engine a minimal Restriction results.

In extreme cases, if due to the severity of the error no other remedy will take effect, the affected control device off.

In a less serious mistake is provided, the Limit the efficiency of the tax for example, by blocking certain functions, that are not needed right now.

Alternatively, the dynamics or the control range are provided restrict the control device.

An optimal solution is, of course, in individual cases repair the occurred error, so no limitation the control device is required. This may for example be the case when a clamping air duct valve with additional control signals again functional can be made.

The device for fault diagnosis is advantageous in a Diesel or gasoline engine used, since in particular the Control equipment with their programs for the injection or the ignition are very complex and easily cause trouble symptoms.

Figur 1

zeigt in schematischer Darstellung ein Blockschaltbild, wie beim bekannten Stand der Technik die bisherige Fehlerdiagnose durchgeführt wird,

Figur 2

zeigt in schematischer Darstellung ein Blockschaltbild mit dem erfindungsgemäßen Ablauf der Fehlerdiagnose,

Figur 3

zeigt ein Flussdiagramm für die Funktion eines erfindungsgemäßen Diagnosemanagers und

Figur 4

zeigt ein Blockschaltbild der erfindungsgemäßen Vorrichtung zur Fehlerdiagnose.

An embodiment of the invention is illustrated in the drawing and will be explained in more detail in the following description.

FIG. 1

shows a schematic representation of a block diagram, as in the prior art, the previous fault diagnosis is performed,

FIG. 2

shows a schematic representation of a block diagram with the inventive procedure of fault diagnosis,

FIG. 3

shows a flowchart for the function of a diagnostic manager according to the invention and

FIG. 4

shows a block diagram of the device according to the invention for fault diagnosis.

For a better understanding of the invention is first on hand illustrated by Figure 1, as in the prior art the procedure for the diagnosis of a fault symptom (also symptom called) expires. In this case, a condition is considered a fault symptom a system or a control device understood, the indicates an error. For example, a voltage may be on a piezoelectric actuator or a deviation be high. An error is a malfunction of the system. For example, a short circuit of a sensor present, clamp a valve, a leak may have arisen or similar.

Referring to Fig. 1, in the left column, trouble symptoms are 1 listed. Error symptoms 1 are the symptoms A1, A2, A3, B1, B2, B3, etc. given the actual errors be assigned. For example, contain the symptoms A1, A2, A3 Errors referring to the injection of a diesel injection system refer: the injection valve closes not, a line is broken, a control voltage is missing etc. Symptoms B1, B2, B3 correspond to a different type of error, for example, a misfire in a gasoline engine etc. The codes are the individual error symptoms 1 easily processed by electronic means.

In the second column, an error table 2 is created in which, according to the ISO standard, the individual codes (diagnostic codes) of the errors that have occurred are listed. This error list is monitored by a diagnostic manager (LIH manager) 3, which later organizes the functional restrictions of the corresponding control devices 5 with their control functions (Control Function 1..6). The LIH manager 3 looks at what type of error has occurred and how serious its effects. In the event of a fault, the LIH manager 3 activates a LIH function 4 (limp home function, emergency function) and thus limits the assigned control device 5 in its functionality. Thus, an emergency run for the engine can be activated or an immobilizer can be deactivated, etc. In general, the LIH function 4 is designed as a worst case reaction and is to ensure that a safe and stable state is restored. Not only a control function of the control devices 5, but it can be affected by cross-control several control functions.
In the embodiment according to the invention shown in Figure 2, however, another approach is proposed to diagnose a fault and then to take appropriate action. The measures taken have the aim of keeping the limitation of the functionality as low as possible in order to ensure safe driving.

First, in the left column of FIG. 2, the trouble symptoms become 1, for example, all error symptoms 1 (symptoms A1, A2, A2, B1, B2, B3, C1, C2, C3, etc.) in a suitable manner, preferably listed in the form of a table or matrix and saved. In case of occurrence of error symptoms 1 in appropriate to be able to respond wisely, it is necessary to take the causative To determine errors. For determining the cause of the error Therefore, in addition to the symptoms A1-3, B1-3, C1-3 Furthermore, information from a system definition 11 and if necessary, also new system states detected by the error reactions have come about. The system definition 11 includes, for example, hardware definitions, vehicle variants, mechanical components and everything at the engine or used on the vehicle.

All information thus obtained is from a diagnostic device 10 first on the basis of their error pattern for determination one or more actual errors used. The diagnostic device 10 looks at the symptoms A1 ... C3 and checks according to the error image, which mechanical-physical or electrical symptoms occurred are what the risks are or what the consequences are from the individual symptoms and other information too are pulling. The evaluation is done with a diagnostic manager 3, the one or possibly more errors filtered out and summed up in corresponding error lists 12 and stored. A transition to an error code, an error confirmation or a generalization of the error - as in the case of State of the art - would not be necessary, but is possible.

The evaluation according to the invention results in the further Advantage that transient influences recognized without further effort and can be eliminated because of the physical causes are known.

Due to the determination of the actual error, the Diagnostic Manager 3 now take appropriate action to a minimal limitation and optimal reliability the control functions of the control devices 5 lead. ever The diagnostic manager takes on the type and severity of the detected error 3 corresponding measures from a catalog of measures 13, where the action is the interface to the functions form the control devices 5. It can be more detailed and more targeted in the control functions of the control devices 5 are intervened, as this in the known State of the art would be possible.

In the action catalog 13 is provided, for example, with a Shut-Off function one or more control functions of the Turn off control devices 5. Another alternative Restriction is, for example, the rule area to limit a control function, especially in the upper range. This may become necessary if in the air duct an air duct valve is stuck and thus the emission standard limit is achieved in an undesirable manner.

Another limitation is also in there, the Limit the performance of the control devices 5 and for example, to block a single function.

Also considered to be particularly advantageous, with a repair attempt to fix the error. So may under circumstances a clamping valve by modified control pulses again be made functional.

In practice, it may be necessary that at the same time to initiate several measures to restrict the functionalities are. It may also happen that after the restrictions new measures are to be taken. This is with the inventive method or device Also possible, as reacts to each error specifically can be.

The flowchart according to FIG. 3 shows a schematic representation a functional sequence of the diagnostic manager according to the invention. The diagnostics manager is in the form of a software program trained and preferably in a main program involved a corresponding control unit. following the functionality of the diagnostics manager is explained in more detail.

The fault diagnosis runs continuously and cyclically during of engine or vehicle operation. The diagnostics manager is therefore constantly activated and supervised all considered too pulling devices such as sensors, functions, etc. Kick in a facility an error, then arise appropriate Error symptoms. For example, according to FIG 3 in position 20 from the diagnostic manager the trouble symptoms A1, B2, C1 detected. In position 21 the symptoms get in shape a table or matrix registered. In position 22 takes place the evaluation and assessment of the detected error symptoms. At the same time, the error symptoms become different categories divided into, for example, functional errors, sensor errors, Actuator error, short to battery or ground, Line break, etc. In position 23 is a comparison performed with stored error images previously used for Example by means of experiments or simulation programs for the individual error causes were simulated and saved.

By this comparison can easily the actual Cause of error determined for the resulting error symptom become. After the error has been clearly identified, the diagnostic manager in position 24 forms a corresponding one unique logical error word, for example, 11100001 to facilitate the further processing of the error.

In position 25, it is decided what minimum measure to take Limitation of functionality at the affected control device is to perform. Available measures are, for example, the reduction of the scope of service, the restriction of a functional area, elimination of an error and / or activating a limp home function (limp home reaction).

In position 26, the corresponding functionality of the affected control unit intervened and optionally one corresponding message issued to the driver of the vehicle. Then the program starts again in position 20.

Figure 4 shows a schematic block diagram of an inventive Device for fault diagnosis in a control device. A diagnostic device 10 is provided with a Memory 9 connected in which filed the error symptoms are. The diagnostic device 10 is further provided with a System definition 11 connected to all the essential information for the control and operation of the internal combustion engine and the vehicle includes, as already closer to Figure 2 was explained. The diagnostic device 10 diagnoses the individual error symptoms. For example, it is checked why is an air duct valve faulty? Likewise all other possible sources of error checked in the Connection with the air duct valve may occur. Such Functions that are error free are considered a potential source of error locked out. The review will continue for so long until finally one or more unique errors, in our example, the clamping air channel valve, left stay. The discovered errors are in a defect list 12 stored, which the LIH manager 3 accesses. The LIH manager 3 accesses a program 17 that is used to diagnose and Evaluation of the error is formed. Furthermore, with Help the program 17 to bring about a decision, which measures to restrict the functions to initiate are.

In particular, the LIH manager 3 must decide how to react must be that the individual control functions through do not interfere with the restriction.

For the decision, the LIH manager 3 accesses a memory 16 to, in which the catalog of measures is stored. He selects one or more appropriate decisions and then controls a device 4 for limiting the functions at. The device 4 then controls the corresponding Control devices 5, which in turn are equipped with sensors, measuring devices, Actuators 15 etc. for the internal combustion engine 14th connected is.

Claims (11)

Method for error diagnosis in control devices (5) of an internal combustion engine (14) of a motor vehicle, which monitor the operability of sensors, actuators and / or system functions (15) and determine the actual cause of the error occurring upon detection of a fault symptom, and wherein a diagnostic manager (3 ) engages in the functions of the control devices (5) such that for the operation of the motor vehicle only a minimal restriction arises, characterized in that the diagnostic manager (3) collects all information at least one error symptom (1), as the cause of an error come into question and that the actual cause of one or more errors is determined on the basis of an error symptom. A method according to claim 1, characterized in that in addition to the error symptom further information, in particular a changed system state is detected and stored, which has arisen by an error response. Method according to one of claims 1 or 2, characterized in that the error symptoms (1) are listed and stored in the form of a table. Method according to one of the preceding claims, characterized in that , depending on the nature and / or the severity of the at least one recognized error, an adapted minimum reaction is initiated at a control device (5) affected by the error. A method according to claim 4, characterized in that in case of a serious, not reparable error, the control device (5) is switched off. A method according to claim 4, characterized in that in a less serious error, the control device (5) is limited in their performance. A method according to claim 4, characterized in that the control device (5) is limited in its control range. Method according to one of the preceding claims, characterized in that at least one repair attempt to eliminate the fault symptom is performed. A method according to claim 8, characterized in that no error response is initiated in successful attempted repair. Device for fault diagnosis in a control device (5) of an internal combustion engine (14) of a motor vehicle, with a diagnostic device (10) for detecting fault symptoms at sensors, actuators and system functions, with a programmable diagnostic manager (3) for evaluating the fault symptoms and with a device ( 4) for limiting the functions of the control devices (5) according to any one of the preceding claims, characterized in that the diagnostic manager (3) is adapted to list information of error symptoms (1) to compare with stored error images, deduce one or more causes of error and taking into account the severity of the error that has occurred, to initiate an adapted minimum intervention to limit the functionality of the affected control device (5). Apparatus according to claim 10, characterized by use in a diesel or gasoline engine (14).

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