EP0937198B1 - Method and device for controlling a drive unit of a vehicle - Google Patents

Abstract

The invention relates to a method and a device for controlling a drive unit of a vehicle. A nominal torque value or nominal power value is produced on the basis of a driver request and then used to control the drive unit. A maximum allowable torque or a maximum allowable power is determined and the nominal value limited to said maximum allowable value if it exceeds the same.

Description

State of the art

The invention relates to a method and a device for controlling a drive unit of a vehicle the preambles of the independent claims.

Such a method and such an apparatus are known from DE-A 195 36 038. There is used to control the Drive unit the torque or the power of the drive unit on electrically at least depending on the Position of a control element actuated by the driver is set. Based on the position of the control element as well at least the engine speed becomes a maximum allowable torque or determines a maximum allowable power that the Torque or the power of the drive unit in the current Operating state must not exceed. From company sizes like the engine speed and the intake air mass becomes the currently set torque or the current one set power of the drive unit is determined with the maximum permissible value compared and an error response initiated when the calculated torque or the calculated Power the maximum allowable torque or the maximum permissible power exceeds. Through these surveillance measures the operational safety of the drive unit is ensured, because in a reliable way against the Driver request increased torque generation of the drive unit is prevented. The response of the monitoring shown is only desired in the event of an actual error. Besides operating situations are conceivable, for example in Transitional states in which the monitoring at tightly specified Tolerances respond without an error. Such behavior is undesirable.

It is therefore an object of the invention to provide measures that an undesired response of the surveillance described avoid.

This is due to the distinctive features of the independent Claims reached.

DE-A 196 19 320 is a control system for a Internal combustion engine based on a torque-oriented Functional architecture known. Thereby the Position of a control element that can be actuated by the driver Taking into account at least the engine speed, a driver target torque educated. This is done by the coordinators for filling adjustment and for crankshaft synchronous Interventions (e.g. ignition angle) with external and internal torque requirements connected. The resulting target moments are then e.g. in target ignition angle and target throttle valve position implemented. Such an engine control system is shown in Figure 1 and 2 shown.

Advantages of the invention

By limiting at least one setpoint for a Torque of the drive unit to the maximum permissible Torque or by an appropriate measure if the Motor control instead of torque values calculated, it ensures that monitoring based on the calculated and maximum allowable Torque or power only responds and an error response initiates when there is actually an error. Thereby the driving comfort and the availability of the drive unit significantly increased. It is particularly advantageous that the tolerances in monitoring the drive unit on the basis of the calculated and maximum permissible torque or performance can be specified very closely, so that at an actual fault condition in the area of the motor control this fault condition was recognized very quickly and very countermeasures can be initiated quickly.

It is also of particular advantage that in an engine control system with a torque-oriented functional architecture the torque setpoints for both the filling path as well as for the quick intervention path via injection suppression, Influencing fuel metering and / or the ignition angle to the maximum permissible torque are limited. This is also in transitional and special situations exceeding the maximum permissible torque and thus a response of the torque monitoring is effective avoided. The same applies to a defined benefit plan Functional architecture.

It is particularly advantageous that a hysteresis between switching on the limitation and deactivation of the limitation, preferably for fast intervention sizes.

The influence of engine drag torque control is advantageous (MSR) considered. Because the engine drag torque control the performance can increase, the limit suspended when drag torque control is active. Thereby becomes an impairment of the engine drag torque function prevented. It is particularly advantageous that this is only in fast path works and the MSR increase the moment in the short term can.

It is particularly advantageous when the ignition angle intervention can be switched off triggering the limit depending on the to make torque to be set via the ignition angle, while turning off the limit depending on the below other torque calculated based on the accelerator pedal position is specified for the fuel metering. Because when switched off Ignition angle intervention is the target torque for the Ignition angle at the moment without intervention, from pre-programmed Maps based on the base torque to be set, is on this way a limitation of the actual torque to the base value reached. This contributes to operational security in an advantageous manner at.

Further advantages result from the description below from exemplary embodiments or from the dependent ones Claims.

drawing

The invention is described below with reference to the drawing illustrated embodiments explained in more detail. It shows Figure 1 is an overview block diagram of a control device for an internal combustion engine, while in Figure 2 a Overview block diagram of a torque-oriented Functional architecture of a control system for a drive unit. Figure 3 shows a block diagram for the determination the maximum permissible torque and the torque on it established surveillance measure. In Figure 4 the limitation of the nominal torque value for the filling path represented by the maximum permissible moment, while in the Figures 5 and 6 two embodiments to limit the Target torque in the fast engagement path to the maximum permissible Moment are shown.

Description of exemplary embodiments

In Figure 1 is a control device for a multi-cylinder Internal combustion engine 10 shown. The control device comprises an electronic control unit 12, which consists of at least a microcomputer 14, an input 16 and one Output unit 18 exists. Input unit 16, output unit 18 and microcomputer 14 are via a communication bus 20 linked for mutual data exchange. The Input unit 16 are the input lines 22, 24, 28 and 30 fed. The line 22 comes from a measuring device 32 for detecting the accelerator pedal position β, the line 24 from a measuring device 34 for detecting the engine speed nmot, the line 28 from a measuring device 38 to record the supplied air mass hfm and the line 30 from at least one further control device 40, for example a control device for traction control ASR, for Gearbox control GS and / or for engine drag torque control MSR. To detect the air mass are depending on the embodiment Air mass, air flow meter or pressure sensors to record the intake manifold or combustion chamber pressure intended. In addition to the farm size shown, the Control unit other sizes essential for engine control like the engine temperature, driving speed, etc. At the Output unit 18 is connected to an output line 42, the on an electrically actuated throttle valve 44, which in Air intake system 46 of the internal combustion engine is arranged leads. Furthermore, output lines 48, 50, 52, 54, etc. shown, which with control devices for fuel metering connected to the cylinders of the internal combustion engine 10 are or for setting the ignition angle in each cylinder serve.

The basic features are shown in FIG. 2 on the basis of a block diagram a torque-oriented functional architecture of a Internal combustion engine control set out. The ones in the block diagrams elements shown are in a preferred Realization parts of the program of the microcomputer, being the blocks special program parts with tables, characteristic curves, Represent characteristic maps and / or calculation steps.

The input lines 22, 24 and 28 are on one element 100 led to determine the driver's desired torque miped. This becomes elements 104 and 106 via a line 102 out, which are also each fed to line 30. The elements 104 and 106 are used to select the motor control specified target torque value milsol and misol according to the supplied target torque values of the driver's request as well as external miext (e.g. ASR, GS, MSR) and internal Interventions miint (e.g. speed, driving speed limitation). The selected setpoints are via lines 108 and 110 led to calculation units 112 and 114. The calculation unit 112 calculates from the supplied Setpoint according to at least engine speed and air mass (Actual fresh gas filling) the correction of the ignition angle and / or the injection suppression and / or the influencing the mixture composition. The Calculation unit 114 from the supplied setpoint Providing at least engine speed and air mass (actual fresh gas filling) the filling by driving the Throttle valve is set via line 42. In return of data is in a preferred embodiment the calculation elements 112 and 114 via the line 116 connected.

The procedure outlined in FIG various interventions on the torque of the internal combustion engine (Intervention from an ASR, from an MSR, from a transmission control, by the driver, etc.) by setting the Filling (slow intervention) via a throttle valve in the Air intake pipe and / or by adjusting the fuel metering and coordinated the ignition angle (rapid intervention).

The control system shown in Figure 1 calculates from its Input variables, output variables of the internal combustion engine, so that an error in the area of calculations to excessive Drive power of the internal combustion engine and thus too can lead to a dangerous driving situation. Therefore, according to Figure 3 provided the correctness of the power control check the calculations used. This takes place in accordance with the prior art mentioned at the outset by that a maximum permissible moment is determined mizul is, this with a calculated actual torque Internal combustion engine is compared and when the maximum permissible torque due to the actual torque e.g. in a shutdown of the fuel supply SKA lie to be executed.

The to determine the maximum allowable torque and Torque monitoring chosen procedure is in a preferred Embodiment shown in Figure 3. Also there, as in the following figures, was the block diagram chosen for clarity. The addressed Functions are in the preferred embodiment as programs of the microcomputer that controls the engine Control unit realized. In at least one map 200 is based on the input variables accelerator position β and engine speed nmot the maximum permissible torque read out mizul. In the preferred embodiment this takes place on the basis of a predetermined map. The maximum torque requirement of the Pedals, which is permissible at a certain speed, under Consideration of torque-increasing functions such as for example the idle control. The from The characteristic value read out is as in the aforementioned State of the art represented by a not shown here Filtered low pass filter. This is only for negative ones Slope of the value coming from the map is active.

In another advantageous embodiment, there are two Maps depending on engine speed and accelerator pedal position provided, the maximum permissible torque as a total value of the two maps is formed. Thereby in a map of the start and the idle speed control below the target speed, which is the maximum allowable torque increase, taken into account. The filtering then only takes place for the values of the other map instead.

The permissible moment determined in this way becomes mizul a maximum value selection MAX, in which there is a predetermined fixed value mdimax is compared. The value represents the maximum adjustable torque. The value mdimax is output when the vehicle speed controller is active is (FGR_ein). When the cruise control is deactivated lies at the corresponding input of the maximum value selection of Value 0. The larger of the torque values supplied (mizul, mdimax or 0) is considered the maximum allowable moment processed by mizul. This ensures that in driving speed control mode when released Accelerator pedal the maximum permissible torque is not too low is and does not respond to the error response. The maximum permissible torque is used to limit the target torques provided ("Exit A") as it is in the Figure 4 to 6 is described.

An actual torque results from this maximum permissible setpoint torque. At a higher monitoring level, that is Actual torque mi is compared with a permissible torque mimax.

This permissible moment is calculated in a similar way and Way like the allowable target torque. An example of a such calculation is in the prior art mentioned at the beginning described. It is carried out in calculation step 203. The maximum permissible torque mimax is usually greater than the allowable torque used for the limitation mizul. Filtering (in 203) here is the intake manifold time constant, Position controller delay and torque increasing functions (e.g. dashpot).

If the actual torque exceeds the maximum permissible torque mimax (comparator 204) may be after a delay time the SKA fuel supply is switched off, in order to master the detected fault. The actual moment miist is at 205 based at least on engine speed nmot and air mass hfm calculated.

In Figure 4, the limitation of the target torque value is milsol shown for the fill path. This is preferred Exemplary embodiment carried out in the coordinator 104, in which the pedal torque derived from the driver is miped in a maximum value selection MAX with external and / or torque increasing internal interventions such as an MSR. The The largest value is then selected in a minimum value selection MIN torque-reducing external and / or internal interventions like an ASR, a speed and driving speed limit, etc. compared. This minimum value selection will be MIN in addition, the maximum permissible torque mizul supplied. It the smallest of these nominal torques is selected and as the target torque value milsol for the filling path. If all torque requirements exceed the maximum permissible Wait, this is the setpoint for the filling path output. In this way, the target torque value becomes milsol for the filling path to the maximum permissible torque limited.

There is also a limitation in the crankshaft-synchronous intervention path carried out. Figure 5 shows a first embodiment of the coordinator 106. First of all, it is comparable a maximum and / or a minimum value selection MIN, MAX from the pedal torque miped, the external miext and / or internal target torques miint a target torque misolv for the crankshaft synchronous Engagement path. The determined target torque becomes misolv then in a comparator 300 with the allowable moment compared to mizul. Exceeds the calculated target torque misolv the maximum permissible value mizul, the comparator gives 300 a logic 1 signal, which is applied to an AND gate 302 is performed. Furthermore, the target torque becomes misolv fed to a comparator 304, in which it with one of the maximum permissible moment mizul formed value (mizul-mihyst) is compared. This value represents the maximum allowable Moment reduced by a predetermined hysteresis moment mihyst. Is the target torque value below this Value, becomes a logic 1 signal to an OR gate 306 output. The output of the OR gate is on the reset input of an RS flip-flop 308 and on the negated ones Input of the AND gate 302 out. The OR gate 306 a signal B_msr is also supplied, which has a positive Signal level when a motor torque control is active. The output of AND gate 302 is switched to Set input S of the RS flip-flop 308 performed. The output signal Q of the flip-flop 308 leads to a switching element 310, which switches to a switching state with a corresponding signal passes in which instead of the target torque value misolv the maximum permissible torque mizul as target torque misolv is passed on for the fast intervention path.

If the target torque misolv exceeds the maximum permissible Moment is not possible when the engine drag torque control is not active (B_msr = 0), the flip-flop 308 is over the AND gate 302 set. The output Q goes to "high" level, so that the Switch 310 switches to the dashed switch position. If the target torque falls below the hysteresis value reduced maximum allowable torque, so the comparator 304 a signal is formed which resets the flip-flop 308, at the same time a level change to logic 0 am Set input takes place via the AND gate 302. This has to Consequence that the output Q of the flip-flop 308 of the switch 310 switched back to its solid position becomes. If engine drag torque control is active (B_msr = 1), the reset input of the Flip-Flops 308 to logic 1 level, while on Set input permanently level 0 is present. In this way the switch 310 is held in its solid position, so that when the engine drag torque control is active Target torque misol for the fast intervention path if necessary mizul raised beyond the maximum permissible torque can be.

In a preferred exemplary embodiment, which is shown in FIG is shown, is from that of the minimum / maximum selection MINMAX determined target torque value misolv a target torque value was mistaken for the ignition angle intervention derived. In particular additive correction components Δmi of an idle control LLR and an anti-jerk function ARF considered. The ignition angle setpoint is included switchable designed (switch 400), so that in certain Operating situations not the target torque value misolv, but a base moment value mibas as the basis for the Setpoint torque value formation for the ignition angle is used. The base moment mibas corresponds to the moment in the current Operating state of the internal combustion engine taking into account the pre-programmed firing angle and λ settings would be taken. The basic moment is based on the air mass hfm, the engine speed nmot and the torque efficiencies of the basic ignition angle and the λ basic setting. The limitation procedure of both nominal torque values corresponds to that in FIG. 5 described procedure. The target torque value for the Ignition angle intervention is supplied to the comparator 300 and thus becomes the decision whether to limit used. In contrast, the target torque value misolv for the fuel path fed to the comparator 304, who decides to cancel the limitation. Is the limitation criterion or the termination criterion is met the switching element 310 operated accordingly. For limitation both target torque values are misol and misolished by the maximum permissible torque mizul replaced.

The invention was for a torque-oriented functional structure described. A corresponding procedure is used for an engine control based on Power values. Thereby the torque value given above through the corresponding power level that with the moment related to the speed, replaced.

Claims (10)

1. Method for controlling a drive unit of a vehicle, at least one desired value for a torque of the drive unit, or at least one desired value for the power of the drive unit being formed at least on the basis of the driver command, this at least one desired value being set by controlling the drive unit, a maximum permissible torque or a maximum permissible power being determined at least on the basis of the driver command, characterized in that the at least one desired value is limited to the maximum permissible torque or the maximum permissible power if it exceeds the maximum permissible value.
2. Method according to Claim 1, characterized in that the at least one desired value is a desired torque value or a desired power value, which is set by influencing the charging of an internal combustion engine.
3. Method according to Claim 2, characterized in that the desired value for the charge path is limited to the maximum permissible value by carrying out a minimum value selection between the quantities which form the desired value and the maximum permissible value.
4. Method according to one of the preceding claims, characterized in that the at least one desired value is a desired torque value or a desired power value for crankshaft-synchronous interventions such as fuel metering and ignition angle.
5. Method according to Claim 4, characterized in that the desired value is compared to the maximum permissible value, and the maximum permissible value is transmitted further as the desired value if the desired value exceeds the maximum permissible value.
6. Method according to either of Claims 4 or 5, characterized in that limitation is switched off if the desired value drops below a specified value, which is derived from the maximum permissible value.
7. Method according to one of Claims 4 to 6, characterized in that limitation is deactivated if engine drag torque control is active.
8. Method according to one of the preceding claims, characterized in that a desired value for the fuel metering is determined and, while taking into account additional interventions, a desired value for the ignition angle path is determined, limitation being triggered if the desired value for the ignition angle exceeds the maximum permissible value and limitation being cancelled if the desired value for the fuel metering drops below a specified value.
9. Method according to one of the preceding claims, characterized in that a further maximum permissible torque or a maximum permissible power is furthermore compared to a computed actual torque of the drive unit or to a computed actual power and a fault response is initiated if the actual value exceeds the maximum permissible value.
10. Apparatus for controlling a drive unit of a vehicle, with means which determine at least one desired torque value or at least one desired power value for controlling the drive unit at least in dependence upon the driver command, and which adjust the torque or the power of the drive unit to this at least one desired value, means being provided which determine a maximum permissible torque value or a maximum permissible power value at least in dependence upon the driver command, characterized by means which limit the at least one desired value to the maximum permissible value if it exceeds the maximum permissible value.

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