DE19902949A1 - Drive unit control method for motor vehicle involves using control parameter dependent on parameter representing tank contents, fill level or remaining range of vehicle with residual contents - Google Patents

Abstract

The method involves determining at least one control parameter for controlling the drive unit depending on operating parameters. The control parameter is dependent on a parameter representing the tank contents, the tank fill level or the remaining range of the vehicle with the residual tank contents. An Independent claim is also included for a drive unit control arrangement.

Description

State of the art

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

In connection with the control of drive units from Motor vehicles are often used on-board computers that the driver has a lot of information about company size essen the drive unit, the motor vehicle and / or with it show related components. For example the current tank content (tank level), the current consumption, the average consumption need, the remaining range, etc., measured or be calculates and displayed to the driver via a display. On such on-board computer is for example from Veröf publication by Knut Gebhardt and Harald Scheufler "Eine new generation of on-board computers in motor vehicles ", ATZ Automobiltechnische Zeitschrift 85 (1983) 2, pages 81 to 84 known. Conclusions from the informa displayed With the known solutions, the driver alone left, even if only a small remaining one Range or only a small tank content determined has been.

It is an object of the invention to provide the available ones White tank and range information ter to evaluate.

This is due to the characteristic features of the indep gene claims reached.

Advantages of the invention

By controlling the drive unit depending on the tank stop and / or the remaining range this becomes available further evaluated information and especially in critical driving situations with low fuel and Re range effectively supported by the driver. An optimal one re utilization of the remaining fuel and an enlargement the remaining range with a small tank capacity or smaller The remaining range is reached. Possible on fuel consumption need and remaining range unfavorable driver intervention are largely reduced.

It is particularly advantageous that the control of the drive unit consisting of an internal combustion engine and / or an au automatic transmission exists, as optimally as possible is carried out, with performance and comfort losses in Purchase. The optimal use of the Fuel available for locomotion placed in the foreground.

It is particularly advantageous that the interventions in the tax The drive unit depends on the tank content and / or the remaining range are accompanied by a flashing on control of the tank reserve light in the display instrument of the Vehicle. This will make the driver aware of the critical situation  tion and the possibly changed control of the An drive unit informed.

It is particularly advantageous that the control to enlarge the range of the vehicle is only made if the tank content (tank level) and / or the remaining range is much smaller than a predetermined threshold, the is below the threshold that is used to control the Tank reserve light leads.

Taxes that are optimal for efficiency are particularly advantageous reduction of the boost pressure, a lock of the overboost function, an effective Degree-optimal adjustment of boost pressure and throttle valves opening after which with the minimum possible boost pressure at maxi times possible throttle opening the driver request for the Locomotion is met. These measures are in particular taken advantage of together.

Another advantageous intervention in the internal combustion engine internal control is the limitation of the engine filling by Dros Selflap intervention or other filling influencing Adjustments to the naturally aspirated engine.

It is also advantageous to switch to a lean driving mode len and switch off the control to Lambda = 1.

Another advantageous intervention measure consists in the Locking the kick-down function and / or in an off finally, according to efficiency criteria, the choice of Gear or gear in an automatic transmission control.

Another advantage is the fact that idle driven when the clutch pedal is not actuated, for example  after a short wait, an automatic engine stop function is turned on after which the engine is turned off. The internal combustion engine is correspondingly activated when the clutch is actuated seem started again.

All of these measures advantageously lead to one maximum vehicle availability in reserve driving mode and for component protection, in particular for the protection of a catalytic converter tors.

Further advantages result from the following Be writing of exemplary embodiments or from the dependent ones Claims.

drawing

The invention is explained below with reference to the embodiments shown in the drawing. Fig. 1 shows an overview block diagram of a Steuerein unit for controlling a drive unit of a vehicle. In Fig. 2, a preferred exemplary embodiment is shown in the implementation of a computer program of the control unit using a flowchart.

Description of exemplary embodiments

Fig. 1 shows a control unit 10 which comprises at least one input circuit 12 , a microcomputer 14 and an output circuit 16 . These components are connected to a communication system 18 for mutual data exchange. The input circuit 12 are fed via input lines, signals representing the operating variables of the drive unit and / or the vehicle, which are evaluated for control. A first input line 20 supplies the input circuit 12 with a signal which comes from a fill level sensor 22 in the fuel tank 24 of the vehicle and presents the respective fill level or the tank content re. Furthermore, via input lines 26 to 30 from corresponding measuring devices 32 to 36 further operating variables such as engine speed, supplied air mass, accelerator pedal position, the oxygen content in the exhaust gas of the internal combustion engine, the boost pressure in engines with a turbocharger, an actuation signal for the clutch pedal, etc., representing signals fed. The quantities supplied are evaluated in the microcomputer 14 as part of the programs implemented there for controlling the drive unit of the vehicle and converted into control signals with the aid of which the microcomputer 14 uses the output circuit 16 to control variables to the drive unit, in particular to an internal combustion engine and / or an automatic transmission. In Fig. 1 are an electrically actuated throttle valve 38 , which is actuated via an output line 40 , a turbocharger 42 , which is actuated via an output line 44 , an automatic transmission 46 , which is operated via an output line 48 and actuators 50 for setting the fuel metering and / or the ignition angle, which are controlled via the symbolized output lines 52 . Furthermore, a tank reserve light 56 is controlled via the output line 54 .

The microcomputer 14 has programs which control the internal combustion engine and / or the automatic transmission as a function of the read signals or quantities derived therefrom by appropriate adjustment of the available control elements. Such controls are known from the prior art. Furthermore, the microcomputer 14 reads the signal from the level meter 22 and forms a measure of the current tank content or of the remaining range which can be achieved with the existing tank content. An example of determining the tank content and calculating the remaining range is known from the prior art mentioned at the beginning. If the tank capacity or the remaining range falls below a given first threshold value, the tank reserve light 56 is activated. This function corresponds to the control of the tank reserve light with low tank capacity, which is common in vehicles today. Furthermore, a second threshold for the tank content or the tank level or the rest of the range is provided, which is smaller than the first threshold and when it falls below the constant activation of the Tan creservleampe in a different control, for example a flashing control, is switched. To extend the range, measures are taken in addition to this modified control of the tank reserve light, which control the drive unit as efficiently as possible. Losses in comfort and performance are accepted.

If the internal combustion engine has a turbocharger, then for optimum efficiency control of this internal combustion engine ne a reduction of the boost pressure, a locking of the Overboost function and / or an efficiency-optimized on position of boost pressure and throttle valve opening specified. The latter measure is aimed at, the driver's request (e.g. regarding a torque or a power of the Internal combustion engine) by a maximum possible throttle valve pen opening with the minimum possible boost pressure and to operate the internal combustion engine accordingly, so that their efficiency is improved.

In internal combustion engines that do not have a turbocharger as additional with turbocharger engines, additional or as an alternative to the above measures, a limitation of the Mo Gate filling by throttle valve intervention or other filling control interventions that influence the lung. To  a maximum position of the throttle valve is specified, so that the intake air mass is limited and thus the force Substance consumption can be reduced or excessive Verify fuel consumption by appropriate driver specification is avoided. Limitations of the maximum engine speed, the maximum torque, the ma maximum driving speed or maximum acceleration supply.

Another measure that is used in addition or as an alternative to the above is to switch off the lambda control and to switch to a lean driving mode. In the considered tank level range, when only a little fuel is left in the tank, short-term air intake means that misfires are to be expected anyway, so that the exhaust gas specifications cannot be reliably complied with. Switching off the lambda control and switching to lean-burn operation is justified in this operating area on the one hand for reasons of catalyst protection (colder exhaust gas due to excess air) and on the other hand by the better efficiency to increase the range, even if slightly higher NO _x values have to be accepted. The driver is also informed of this operating status by the flashing tank light.

In addition or as an alternative to the above measures in vehicles with automatic transmissions, the kick-down Function locked and the gear stage or gear selection off finally made according to efficiency criteria. Correspond The switching characteristics are determined in such a way that is only shifted into another gear when in be standing gear the operation of the internal combustion engine ver consumption or efficiency is less favorable.  

For engines with automatic switch-off in empty running operation can alternatively or in addition to the above Measures should be provided in idle mode at not be actuated clutch pedal after a short waiting time the engine turn off automatically. The same applies to the clutch actuation the engine automatically starts again.

All of these measures are carried individually or in any way combination to increase the remaining range at and are just hesitating to stay put due to lack of fuel if the driver is driving unfavorably.

In the preferred embodiment, the procedure outlined above is implemented as a computer program of the microcomputer of the control unit. An example of such a program is outlined using the flow chart in FIG. 2. This flow chart is run through at predetermined time intervals when the supply voltage is switched on.

After the start of the program part, a size representing the tank level T and / or a size R representing the range is read in in the first step 100 . In the subsequent step 102 , at least one of these variables is compared with a second threshold value. If this variable exceeds the second threshold value, the corresponding variable is compared with a first, larger threshold value (step 104 ). If the corresponding size falls below the first threshold value, that is to say if it lies between the first and second threshold value, the reserve light is continuously activated (step 106 ). Thereafter, just as in the case of a no answer in step 104 , if the checked variable lies above the first threshold, the operation of the drive unit is carried out without restrictions as part of normal operation. The program is then ended and repeated in the next time interval.

If step 102 has shown that the checked variable is smaller than the second threshold, then the lamp is activated in accordance with step 108 in a flashing manner. Then, in step 110 , an efficiency or consumption-optimized control of the drive unit is carried out with at least one of the measures described above. After step 110 , the program is ended and repeated at the next time interval. The efficiency and consumption-optimized control of the drive unit takes place as long as the checked size, ie the tank level or the range, is smaller than the second threshold. After refilling the tank, the system switches back to normal operation.

The program outlined in Fig. 2 is carried out in the engine control unit, from which the reserve lamp is also controlled.

In other versions, in addition or as an alternative to the measures described above, at least one of the following measures is initiated if the monitored variable (tank content, remaining range) falls below the threshold value:
The clutch of an air conditioning compressor is opened so that it no longer loads the engine; Electric heaters are switched off, e.g. B. the coolant heater in some diesel engines; Heaters that run on fuel are switched off, such as auxiliary heaters, etc .; The clutch of a mechanical turbocharger is opened so that it no longer loads the engine; For engines with gasoline direct injection efficiency-reducing interventions by means of the throttle valve are prohibited, e.g. B. homogeneous operation for catalyst regeneration.

Claims (7)

1. A method for controlling a drive unit, wherein at least one control variable for controlling the drive unit is determined as a function of operating variables, characterized in that the control variable is dependent on a variable which determines the tank content, the tank fill level or the remaining range of the vehicle with the fuel still present. 2. The method according to claim 1, characterized in that the drive unit from an internal combustion engine and one automatic transmission. 3. The method according to any one of the preceding claims, since characterized in that the size ver with a threshold the tank reserve light will be equalized flashing. 4. The method according to any one of the preceding claims characterized in that the size ver with a threshold is compared, below which an efficiency or consumption-optimized control of the drive unit follows. 5. The method according to any one of the preceding claims characterized in that the size ver with a threshold is compared, which is larger than the threshold for flashing Control of the lamp or for optimized control of the on  is the drive unit when the reserve falls below light is constantly controlled. 6. The method according to any one of the preceding claims, characterized in that for optimal control of the drive unit at least one of the following measures is taken:

• - reduction of the boost pressure,
• - locking an overboost function,
• - Efficiency-optimal setting of boost pressure and throttle valve opening, the driver's request being fulfilled with the minimum possible boost pressure with the maximum possible throttle valve opening,
• - limiting the engine charge, the speed, the driving speed, the torque and / or the acceleration of the vehicle,
• - switching to a lean driving mode,
• - locking of the kick-down function,
• - Choice of gear or gear according to efficiency criteria,
• - Automatic engine stop when idling and clutch pedal not activated, especially after a short waiting period with automatic engine start when clutch is actuated,
• - opening the clutch of an air conditioning compressor,
• - switching off electric heaters,
• - switching off heating systems that run on fuel,
• Opening the clutch of a mechanical turbocharger,
• - For engines with direct petrol injection, the efficiency-reducing interventions are prohibited by means of the throttle valve.

7. Device for controlling a drive unit, with egg ner control unit ( 10 ), which determines at least one control variable for controlling the drive unit as a function of at least one operating variable, characterized in that the control unit determines a variable which determines the tank fill level, the tank content or represents the remaining range and the control unit determines the control variable depending on this variable.