EP0826102B1 - Method and device for controlling a vehicle drive unit - Google Patents

Abstract

The invention relates to a method and a device for controlling a vehicle drive unit. According to said method the control functions for the power of the drive unit and the monitoring of said control functions are carried out by a single microcomputer. A monitoring module separated from the microcomputer is provided to check the monitoring functions and send test signals to the microcomputer at a given time. Said microcomputer subsequently calculates the monitoring function of interest on the basis of test data. The result of the calculation is transmitted to the monitoring module which checks the operation capacity of the function monitoring system in the microcomputer by comparing it with stored values.

Description

State of the art

The invention relates to a method and a device for controlling a drive unit of a vehicle.

Such a method and device in the unpublished German patent application P 44 38 714.8 from October 29, 1994. There is one Control unit provided, which is a microcomputer having both controlling the performance of the Drive unit (in the case of an internal combustion engine via Air supply, fuel metering and / or ignition angle) as also monitoring the correct functioning of this Executes control programs. The program structure of this Microcomputers essentially consist of three separate levels (see also the following Description of Figure 1). In a first level, the Control functions calculated. On a second level the correct functioning of the control functions of the first level checked on the basis of selected input and output signals. A third level is a review of the in the second level monitoring carried out as part of a Process control realized in interaction with one Monitoring module (watch dog or security computer) correct processing of the monitoring steps checked. For this purpose, the monitoring module makes one of predetermined ones Questions selected question by forming a Partial answers of the programs of the second level answered and the monitoring module for error detection is sent back. In the preferred embodiment the second level monitors the air setting of the Internal combustion engine and switches this in the event of a fault Air setting off or initiates an emergency run. The Monitoring module intervenes in this embodiment both to the final stage for the air supply controlling Actuators as well as on the output stages for fuel metering and ignition on. Measures to review the Function monitoring carried out in the second level Calculations in addition to checking the program flow not described in the known solution.

Another error monitoring of control computers of internal combustion engines is known from EP-A-512 240.

It is an object of the invention to take measures to check the to be specified as part of the function monitoring.

This is due to the characteristics of the independent Claims reached.

Advantages of the invention

The solution according to the invention allows the detection of Microcomputer errors that are similar on both the calculation of the control functions as well as on the Calculation of the monitoring functions. Therefore are also advantageously dormant mistakes recognized, for example a quantitative incorrect computing monitoring function.

It is particularly advantageous that in the context of operations according to the invention are not used, which are separate from the programs to be monitored, but the program code to be monitored. This allows the solution according to the invention an almost 100 percent Checking the function monitoring of a controller for a drive unit.

It is particularly advantageous that with a suitable choice of Test data records in all relevant value ranges representative tests can be carried out. Thus a bit-precise check of a monitoring function of a Power control of a drive unit created.

Further advantages result from the following Description of exemplary embodiments or from the dependent claims.

drawing

The invention is described below with reference to the drawing illustrated embodiments explained in more detail. It shows Figure 1 is a structural diagram of a control device for a Drive unit, while in Figures 2 and 3 based on Flow charts a first embodiment of the solution according to the invention is shown. Figure 4 shows Waveforms for this embodiment. 5, 6 and 7 is a second embodiment of FIG solution according to the invention as a block diagram or as Flow charts shown.

Description of exemplary embodiments

In Figure 1 is a control unit 10 for controlling a Drive unit of a vehicle, preferably one Internal combustion engine, shown. The control unit 10 comprises including an input circuit 12, the Input lines 14 and 16 from measuring devices 18 and 20 are fed. In the input circuit 12, the Input signals from the control unit processed and one Microcomputer 22 supplied. In the preferred embodiment a power control is the Measuring devices 18 and 20 around two measuring devices for Detection of the degree of actuation of a driver-operated Control element, for example an accelerator pedal. The two Measuring devices can be constructed redundantly or in another embodiment than continuous Measuring device (for example potentiometer) and discontinuous measuring device (e.g. switch) be executed. Whose supplied via lines 14 and 16 Measurement signals are separated in the input circuit 12 processed from one another and preferably on separate paths 24 and 26, for example via two input ports or two A / D channels, supplied to the microcomputer 22. In addition to these measurement signals the control unit or the microcomputer are further Measured variables supplied to the drive unit and / or the vehicle, e.g. Engine speed, position of a power control element, etc., which is not shown in Figure 1 for reasons of clarity is. The microcomputer 22 is regarding its program structure essentially divided into three levels. On a first level 28 are the programs 30 for performing the control for the Drive unit summarized. In the preferred Embodiment are programs that are based on the basis of the degree of actuation of the control element (supplied via connections 44 and 46) and other farm sizes Set the torque of the drive unit in preferred Embodiment of an internal combustion engine via the air supply an electrically operated throttle valve, the Fuel metering and calculate the ignition timing. Accordingly, the microcomputer 22 has output lines 32 and 34, which lead to amplifiers 36 and 38, which in turn corresponding output lines 40 and 42 ignition timing, Adjust fuel metering and air supply. In a second Level 48, the programs 50 are summarized for Function monitoring of the control functions 30 serve. Here are in a preferred embodiment from Permitted torque of the drive unit derived from the driver's request compared with the set torque and if exceeded detects an error condition. In the preferred embodiment the control of an internal combustion engine can also Plausibility checks regarding the degree of activity of the Control element and the setting of the throttle valve or corresponding values for the engine load are carried out. The Level 2, there the programs 50 for function monitoring, accordingly, on the one hand, the input signals with respect to the Degree of actuation of the control element supplied (connections 52 and 54), on the other hand, calculation results of the programs 30 for the control functions (connections 56 and 58). In another Embodiment are in addition or alternative to the Calculation results for the engine load, the Throttle valve position and / or the torque supplied. about the output line 60 of the microcomputer 22 takes the Function monitoring 50 in the preferred embodiment Influence on the output stage 38 for controlling the throttle valve. In addition to the first and second levels, the program structure shows of the microcomputer 22 on a third level 62, in which the Programs 64 for sequence control of function monitoring 50 are summarized. The programs 64 communicate via Connection lines 66 and 68 with a monitoring module 70 a watch dog separated from the microcomputer or Security computer 72. The connecting line 66 chooses that Monitoring module 70 in the programs 64 for Sequence control predetermined sequences. These consist in essential in that the flow control 64 in the Function monitoring 50 the execution of an arithmetic operation (Answer) based on partial responses that are selected after Program steps are formed, triggers (via connection 74), the result of which is fed back by the process control 64 (via connection 76). The result or one of them derived size passes the flow control 64 over the Connection 68 to the monitoring module 70, which the Answer with his question on line 66 compares. In the event of an error, the monitoring module 70 takes over the output line 68 influences the output stages 36 and 38.

In the preferred embodiment, the degree of actuation of the control element a setpoint for the torque of the Drive unit derived. The actual torque will be this setpoint by adjusting the air supply, the Fuel metering and the ignition angle approximated.

According to the invention for the extended monitoring of the function of the Microcomputer, at least in the critical case of the released Control element (idle), in a first embodiment The following is provided: The monitoring module 70 sets cyclically (e.g. every 200 msec) at least in predetermined Operating states, e.g. the control element is released, is held stationary, the level of activity in one predetermined range of values and / or after expiry of a predetermined operating time or number of operating cycles Stimulus information via the serial interface or a port pin to the microcomputer 22. This reacts to this Stimulus signal by at least for parts of the Monitoring function (preferably for the actual torque calculation or for the calculation of the permissible torque) not those in the Storage cells stored, the monitoring function lying sizes (e.g. actual torque determining sizes such as load signal and set ignition angle or Degree of actuation) is the basis, but test signals which in the corresponding operating status the monitoring function violate (e.g. result in a high actual torque or a low allowable moment). If the level 2 programs in this case, an error must be recognized become. The existing error counter in level 2 is accordingly run up. Expected at a certain level of the error counter the monitoring module a special response of the microcomputer 22, for example the transmission of an error or reset signal. The monitoring module 70 receives one of these Signal, the stimulus signal is withdrawn and one functional second level recognized. The corresponding one Signal within a specified period of time (ramp-up time of the Counter) is not recognized, either one of the programs is the Level 2 is faulty or a function is active in which the Driver does not press the pedal (e.g. Vehicle speed controller, drag torque controller) and that Increase engine torque beyond the driver's request (at least then, if the actual torque is influenced by the test signals). To check this, the monitoring module 70 holds the stimulus signal upright. The microcomputer 22 now calculates as part of its Function monitoring the torque monitoring based on the Driver request idle and not as for the increasing Intervention provided with other permissible moments. In this In any case, the error counter must run up, so that the corresponding reaction signal of the microcomputer 22 triggered becomes. If such a signal from the monitoring module 70 does not received, then an error in the area of Function monitoring recognized and the corresponding shutdown or emergency measures initiated via the output line 78.

A first embodiment of the solution according to the invention is shown in Figures 2 and 3 using flow charts. These outline the implementation of the solution as programs in the Monitoring module and function monitoring.

The flow chart shown in Figure 2 represents a program of Monitoring module 70. This is one of the above-mentioned operating situations in given Run through time intervals (e.g. every 200 msec). In the first Step 100 sends the stimulus signal to the microcomputer 22 (FR = Function calculator). The stimulus signal is thereby for example by a change in level, by a signal with predetermined duty cycle or predetermined voltage level an input line of the microcomputer 22 realized. in the Subsequent step 102 is checked whether a predetermined period of time while the error counter is safe Has reached the maximum response signal from Microcomputer 22 was recognized. If this is the case, then according to Step 104 considers the test complete and the Program part ended. He will be there when the next predetermined operating situation initiated again.

In another advantageous embodiment, instead of the response signal of the microcomputer 22 is the current one Transfer error counter reading to monitoring module 70. This then recognized based on the time history of the error counter or if the limit value is exceeded, the correct function or malfunctioning of the microcomputer 22.

The monitoring module does not recognize this due to the stimulus signal expected work of the microcomputer in step 102, see above the output of the stimulus signal is maintained in accordance with step 106. Thereupon it is checked again according to step 108 whether the Response from the microcomputer 22 or the expected behavior of the Error counter of the microcomputer 22 is present. Is that the case, the test is then regarded as completed in accordance with step 110 and the program terminates while according to the contrary Step 112 from an error in the area of the function monitoring of the microcomputer 22 is assumed and corresponding Error responses initiated by the monitoring module. This consist essentially in switching off the power amplifiers for the fuel metering, the ignition angle and the air supply or in an emergency run, which is a limited one in particular performance-limited control of the drive unit results. After step 112, the program is ended.

FIG. 3 shows the corresponding program of level 2, the function monitoring of the microcomputer 22. This is initiated at predefined time intervals (eg a few milliseconds). After the start of the program part, the degree of actuation of the control element β and the engine speed N _{mot are} read in in a first step 200 and an allowable engine torque MIZUL is determined in accordance with step 202 on the basis of a predetermined map, a predetermined table or predetermined calculation steps from the degree of actuation β and the engine speed N _mot . This permissible torque is dimensioned such that it is not exceeded when the microcomputer is operating correctly, taking into account all tolerances of the actual torque of the drive unit. A check is then made in step 204 as to whether the monitoring module has a stimulus signal. If this is not the case, the function monitoring is initiated with steps 206 and 208. For this purpose, the load signal TL (for example, formed from air mass and engine speed) and the set ignition angle ZW are read in (step 206) and, on the basis of these two variables and the engine speed, according to a predetermined map, a predetermined table or predetermined calculation steps, the one emitted by the internal combustion engine Moment MI _is determined. In the subsequent query step 210, it is checked whether an intervention which increases the torque compared to the target torque specified by the driver is active, for example, by a vehicle speed controller (FGR) or an engine drag torque controller (MSR). If this is the case, according to step 212 the permissible torque MIZUL is set to a maximum value Mi _max which is predetermined for these operating states and which is, for example, speed-dependent or speed-dependent. After step 212, as in the case of a "NO" answer in step 210 after step 214, a comparison is made between actual torque MI _1st and permissible torque MIZUL. If the calculated actual torque is greater than the calculated permissible torque, the error counter F is incremented in accordance with step 216, and decremented in accordance with step 218 in the opposite case. In the subsequent query step 220, it is checked whether the error counter has reached its maximum value. If this is the case, a corresponding signal is sent to the monitoring module 70 (safety computer SR) in accordance with step 222 and the program is ended in step 220 as in the case of a "NO" answer.

If step 204 shows that a stimulus signal is present, a counter i running in this part of the program is incremented in accordance with step 224. Thereupon, selected test signals for the engine load TLT and the ignition angle ZWT are specified in step 226 and an actual torque is determined in accordance with step 228 in accordance with step 208. In the subsequent query step 230, the counter i is compared with a maximum value i _max . If this maximum value has not been reached, the process continues with step 210, in the other case the system jumps directly to step 214. The counter i ensures that the desired test situation is generated if the stimulus signal is still present and the vehicle speed controller or drag torque controller is active. The maximum value i _max is dimensioned with a view to the time span that the error counter needs to reach its maximum value (eg 2-3 program runs). If the actual torque exceeds the permissible torque and the error counter runs up properly, the reaction signal is output to the monitoring module in accordance with step 222 if the monitoring function is functioning correctly.

In another advantageous embodiment the error counter reading at least in a test situation transmitted.

The solution according to the invention is shown in FIG Time charts shown. Figure 4a shows the course of time of the stimulus signal, Figure 4b that of the actual and the permissible Moments, Figure 4c that of the error counter, Figure 4d the intervention a vehicle speed or drag torque controller and Figure 4e shows the time course of the feedback signal of the microcomputer 22 to the monitoring module 70.

At a first time T0, the microcomputer 22 receives the stimulus signal released by the monitoring module (cf. FIG. 4a). The actual torque then determined according to test data (FIG. 4b, solid line) immediately exceeds the permissible torque calculated on the basis of the degree of actuation (FIG. 4b, dashed line). Accordingly, the error counter runs up until the maximum error level F _{max has been} reached at time T1 (cf. FIG. 4c). This leads to the output of a corresponding error signal according to FIG. 4e to the monitoring module, to the resetting of the stimulus signal and to the termination of the test situation (cf. FIGS. 4a, 4b). In this example, the monitoring worked correctly. After time T1, the error counter is decremented again.

At a further point in time T2 is a Vehicle speed controller activated (Figure 4d). In this Operating situation, the permissible torque is increased (see Fig 4b). At time T3, the monitoring module sets a stimulus signal to the microcomputer 22. According to FIG. 4b, this leads to Calculation of the actual torque based on test data. In this case According to test data, the actual torque exceeds the permissible torque Not. This means that at time T4 the stimulus signal is maintained and the allowable moment is determined as the cruise control would not be engaged. Thereby If the monitoring is working, the actual torque exceeds in the previous situation the permissible moment (see figure 4b), so that from time T4 to time T5 Error counter is incremented. Reaching the maximum Error counter status leads to the output of the time T5 Error signal to the monitoring module, so that here too correct functioning of the monitoring is proven. From the Time T5 becomes the error counter according to FIG. 4c again decremented.

A second embodiment of the solution according to the invention is shown with reference to Figures 5 to 7. This too Embodiment serves to check whether the Monitoring tasks of a microcomputer properly and be performed reliably and will in particular at Control systems used in which the control functions and the monitoring functions on the same microcomputer are implemented. By transferring the error counter or a signal derived therefrom according to the first Embodiment is a direct review of the Monitoring function ensures a bit-precise check however, the monitoring function does not take place. Much more a kind of threshold monitoring is carried out. For bit-precise verification of the calculations within the scope of the Level 2 surveillance is therefore performed according to the second Embodiment the level 2 monitoring function alternating with at least in predetermined operating situations real data and calculated with test data. Preferably at the calculation with test data the original program of level 2 used with changed data. In another advantageous In the embodiment, a copy of the program is used.

When calculating the monitoring with real data, the actual values of pedal position and engine speed permissible engine torque determined from the values for filling, Speed and ignition angle an actual torque. By forming differences a plausibility violation is checked. In case of a Injury, preferably in the case of a compared to permissible engine torque to large actual torque, runs in Error counter going. Following this calculation, there is Monitoring module a test signal from what this calculation not with real, but with test data (for engine speed, Pedal position, filling and ignition angle). This test data are either stored in the monitoring module and are via a Interface transmitted to the microcomputer 22 or are in Microcomputer 22 stored as different test data sets, the monitoring module via a transmitted index selects. There is only one for a fixed test data record right solution for the difference between allowable moment and Actual moment. This correct one belonging to each test data set Solution is known to the monitoring module. The microcomputer 22 transmits this difference to the monitoring module that the Checks correctness of the result. The Test data records selected so that both plausible results and implausible results can also be determined. Therefore, too be checked whether the monitoring level is still able distinguish plausible states from implausible ones.

This second exemplary embodiment is shown in FIG. 5 using a block diagram which symbolically represents the program structure in level 2 of the microcomputer 22. The engine speed N _mot , 302 the pedal position β, 304 the filling TL and 306 the set ignition angle ZW are fed to the monitoring function via the connections 300. These signals are forwarded via switching elements 308, 310, 312 and 314, respectively. The engine speed is guided to a first map 316 for determining the permissible engine torque, to a second map 318 for determining the optimal engine torque and to a map 320 for determining the optimal ignition angle. The pedal position β is led to the first map 316 via a filter 322, the filling to the second map 318 and the third map 320. The optimum ignition angle (maximum efficiency of the internal combustion engine) determined in the characteristic diagram 320 is passed to an addition stage 322, in which the difference between the optimal ignition angle and the actually set one is formed. This difference is led to a multiplication point 326 via a characteristic curve 324. The characteristic curve 324 converts the deviation of the ignition angle into a deviation of the torque from the optimal torque (highest efficiency). In the multiplication point 326, the optimum engine torque is corrected by the ignition angle deviation in accordance with the torque correction. The result is a measure of the actual torque. This is fed to an addition point 328, which is also fed from the map 316 the permissible torque. By subtracting the permissible torque from the actual torque, the torque difference is formed, which is led to the monitoring module via the connecting line 330. Furthermore, the torque difference is fed to a threshold switch 332, which increments the error counter 334 if the permissible torque is exceeded by the actual torque. In the preferred exemplary embodiment, the error counter status is transmitted to the monitoring module at least when its maximum value is reached via connection 336. A connection 338 is supplied by the monitoring module, which transfers the switching elements 308 to 314 from the normal position to the test position shown in broken lines. In this position, the connections for engine speed, pedal position, filling and ignition angle are connected to tables or memories 340, 342, 344 and 346 which contain various test data records. These are selected depending on the selection signal supplied by the monitoring module via connection 348.

Examples of the implementation of the solution according to the invention in Framework of the second embodiment as computer programs are based on the flow diagrams of Figures 6 and 7th shown. Figure 6 describes a in the monitoring module running program, while FIG. 7 a in the microcomputer 22nd running program describes.

The program of the monitoring module shown in FIG. 6 is called up at predetermined time intervals, wherein in an advantageous exemplary embodiment the program part is only called up in at least one of the above-mentioned, specific operating situations. In the first step 400 of the program part shown, the test signal is formed and output to the microcomputer 22 and a test data record or an index defining a test data record is transmitted. In the preferred exemplary embodiment, the test data are read out on the basis of the current operating state (described by accelerator pedal position and engine speed or filling) and alternately selected as a plausible and implausible combination. As part of the implementation of the solution according to the invention, other strategies are used with regard to the initiation of the test, the selection and specification of the test data (for example only plausible data, only implausible data). In the subsequent step 102, the torque difference MI _Diff calculated by the microcomputer 22 and, if appropriate, the error counter reading are then read in, and in step 404 it is checked based on stored difference values whether the calculated result is correct. If the result is correct, the program is started again with different test data. If the result does not match, an error state is recognized in accordance with step 406 and the program part is ended. Depending on the strategy selected, the corresponding reactions (switching off the output stages) can be carried out if the error has already been detected once or has only been detected several times. In other advantageous exemplary embodiments, an error counter runs in the monitoring module, error measures being taken when its maximum value is reached. When the error counter reading is transmitted, the monitoring module checks the chronological course of the counter reading and / or the reaching of the maximum value.

The program part shown in FIG. 7 shows a program that is started in the microcomputer 22 at predetermined time intervals. After starting the program, the test variables for the pedal position, the engine speed, the ignition angle and the filling are selected or read in the first step 500 if a test signal is present. If there is no test signal, the measured or calculated actual quantities are read in. A situation is described below in which a test signal is present. In normal operation, the program runs accordingly, except that the actual operating variable values are used instead of the test data. In step 205, the signal value for the pedal position is subjected to a predetermined filtering. Then, in accordance with step 504, the permissible torque MIZUL is determined on the basis of the test values for pedal position and engine speed and the actual torque MI _{actual is} determined on the basis of the test variables for filling, ignition angle and engine speed. In the subsequent step 506, the differential torque MI _{Diff is formed} as the difference between the actual torque and the permissible torque and is output to the monitoring module after step 508. In the subsequent step 510, it is checked whether the differential torque is greater than 0. If this is the case, the error counter 512 is increased by 1, otherwise it is decremented (step 514). A check is then carried out in step 516 as to whether the error counter has reached its maximum value, an error being recognized in the event of a positive answer in accordance with step 518, and a corresponding signal being output to the monitoring module if necessary. If the error counter has not yet reached its maximum value, the program is ended and restarted at the specified time. Alternatively, the current error counter status is transmitted.

A combination of the first and second embodiment. The microcomputer 22 the monitoring module both the difference between the Torque sizes as well as the error counter transmitted. On the Based on these variables, the monitoring module monitors both the bit-precise calculation of the torque difference as well How error detection works, especially the Differentiation between plausible and implausible deviations the allowable from the calculated moment.

The control function for torque setting runs regardless of Test phases for function monitoring always based on the actual values, so that the operation of the test Drive unit is not affected.

The solution according to the invention is in the same way Consideration of the corresponding company size also with Diesel engines used.

The monitoring function is preferred in the described Embodiment based on the indexed moment, i.e. of the internal combustion engine in the by combustion generated torque, described. In other The monitoring and thus also the exemplary embodiments Test another torque value (e.g. the given torque) Fill or load value, a performance value or pedal position and throttle valve position. The invention Solution with the specification of test data sets will then carried out accordingly.

In addition to calculating the allowable torque on the basis the accelerator pedal position are in the corresponding Operating states also the setting of others Operating elements (e.g. a cruise control), Setpoints of external interventions that have a setpoint torque value specify (e.g. vehicle speed controller, Engine drag torque controller, traction controller, etc.) and / or special operating parameters (e.g. driving speed, Slip, speed, etc.) in these operating conditions at the Determination of the permissible torque is taken into account and on this way monitoring and reviewing it also in this or for these operating conditions guaranteed.

Will the solution according to the invention in diesel engines used, instead of filling is the amount of fuel and instead of reading ignition start reading.

In addition to the transmission of the difference between permissible and Actual torque and / or the error counter reading are in others Other intermediate sizes, e.g. the allowable moment and the actual moment, an evaluated difference if threshold values etc. are exceeded.

Claims (11)

1. Method of controlling a drive unit of a vehicle, a microcomputer being provided which controls the power of the drive unit by means of first programs as a function of operating parameters of the drive unit and of the vehicle and monitoring this power control by means of second programs using selected operating parameters, the programs running in the microcomputer for monitoring purposes being checked for functional capability by a monitoring module, the microcomputer receiving a test signal from the monitoring module in at least one operating condition, whereupon the microcomputer carries out the specified monitoring function on the basis of selected test data and transmits the result of the monitoring and/or intermediate parameters to the monitoring module.
2. Method according to Claim 1, characterized in that the monitoring module checks the functional capability of the monitoring function in the microcomputer by comparing the result transmitted with an expected value.
3. Method according to one of the preceding claims, characterized in that the monitoring function is carried out on the basis of a permissible engine torque calculated as a function of the position of operating elements or external specifications and of a calculated actual engine torque.
4. Method according to one of the preceding claims, characterized in that the drive unit is an internal combustion engine and that the permissible torque is calculated on the basis of engine speed, accelerator pedal position and the setting of other operating elements or external specifications and the actual torque is calculated on the basis of the charge and/or fuel quantity, the engine speed and the set ignition angle or beginning of injection.
5. Method according to one of the preceding claims, characterized in that a permissible torque and an actual torque are determined and compared with one another on the basis of test data in order to check the monitoring function.
6. Method according to one of the preceding claims, characterized in that in order to check the monitoring function when the test signal has been given, an actual torque is determined on the basis of test signals and is compared with the permissible torque determined on the basis of measured values.
7. Method according to one of the preceding claims, characterized in that the difference between actual torque and permissible torque is transmitted to the monitoring module which, on the basis of stored measured parameters associated with the test data, checks the correctness of the calculation of the difference in the microcomputer.
8. Method according to one of the preceding claims, characterized in that when the actual torque exceeds the permissible torque, a fault counter is incremented whose counter reading, or the fact that a maximum counter reading has been exceeded, is transmitted to the monitoring module which determines the functional capability of the monitoring on the basis of the signal transmitted.
9. Method according to one of the preceding claims, characterized in that, in the case of an intervention which can raise the torque beyond that demanded by the driver, the maximum permissible torque is set to a higher value independent of the demand of the driver, the monitoring module then causes the microcomputer - where no reaction of the microcomputer to faulty test data is detected - to employ the permissible torque derived from the pedal for checking the monitoring in this operating condition also.
10. Method according to one of the preceding claims, characterized in that when a fault case is detected by the monitoring function, the final stage for the air setting is blocked, and when a fault case is detected by the monitoring module, the final stage for the air setting and/or the final stages for fuel metering and also ignition, if necessary, are blocked.
11. Appliance for controlling a drive unit of a vehicle, having a microcomputer which controls the power of the drive unit by means of first programs as a function of operating parameters of the drive unit and of the vehicle and which monitors the control functions carried out for power control purposes by means of second programs using selected operating parameters, having a monitoring module which checks the monitoring in the microcomputer, the monitoring module generating a test signal for the microcomputer in at least one operating condition, the microcomputer carrying out the monitoring of the control functions on the basis of predetermined test data because of this test signal and transmitting the result of the calculation and/or intermediate parameters to the monitoring module.

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