WO2011104249A1

WO2011104249A1 - Method for individually operating an internal combustion engine, and control device for an internal combustion engine

Info

Publication number: WO2011104249A1
Application number: PCT/EP2011/052636
Authority: WO
Inventors: Michael Jung; Dietmar Ellmer; Bernhard Klingseis
Original assignee: Continental Automotive Gmbh
Priority date: 2010-02-26
Filing date: 2011-02-23
Publication date: 2011-09-01
Also published as: DE102010009383A1

Abstract

The invention relates to a method for individually operating an internal combustion engine of an individual motor vehicle, wherein the internal combustion engine comprises at least one valve lift adjusting device for at least one valve, and the valve lift adjusting device is controlled such that a fuel consumption of said internal combustion engine is as low as possible, or relatively low as possible, at a given operating point. The invention further relates to a control device for an internal combustion engine of a motor vehicle, implemented such that a method according to the invention can be performed and/or is performed by the control device.

Description

description

Method for the individual operation of an internal combustion engine, and control device for an internal combustion engine

The invention relates to a method for the individual operation of an internal combustion engine of a single motor vehicle, wherein the internal combustion engine has at least one valve lift adjusting device for at least one valve, in particular an inlet valve. Ie. The invention also relates to a method for the individual operation of a valve lift adjusting device of an internal combustion engine. Ie. Furthermore, the invention relates to a method for Hubadaption, in particular a Kleinsthubadaption, a variable Ventilhubsystems or a valve lift adjusting device. Furthermore, the invention relates to a control device for an internal combustion engine of a motor vehicle, which is designed such that by means of the control device, a method according to the invention can be carried out and / or carried out.

A control and / or regulation of internal combustion engines is usually carried out by means of an electronic control device (engine control unit ECU). The control device is connected to actuators or actuators and sensors of the internal combustion engine. By transmitting appropriate control signals to the actuators, the operating parameters and manipulated variables of the internal combustion engine, such. B. throttle valve angle and ignition timing, adjusted such that the torque produced by the internal combustion engine corresponds to a torque request of a motor vehicle driver. The advantage of the electronic control / regulation is that the manipulated variables can be optimized in terms of the efficiency and the Schadstoffausstoßes the internal combustion engine. In the control device, control functions in the form of software are implemented, which resort to an extensive database, mainly in the form of maps. A mapping of the maps is usually done on engine test benches or during test drives. However, the number of test motors on which the rating is made is very limited. However, the data obtained are used for all engines of this type. Due to manufacturing tolerances and due to changes over the lifetime of a particular internal combustion engine, it may be that the database obtained on the few test engines is not always an optimum for each individual internal combustion engine. This gives away power and consumption potential.

Previous valve lift adjustment devices for internal combustion engines usually only have one adjustment possibility of the relevant valves for all cylinders simultaneously. However, the filling differences of the cylinders increase with decreasing strokes of the valves. So far, this problem is encountered such that a sensor, the various effects of increasing filling differences, such. B. cylinder-selective lambda detection, cylinder-selective smoothness detection, cylinder pressure, vibration sensor o. Ä. Recognizes. A miniature stroke adaptation is carried out by way of a control or regulation, wherein a minimum lift of the valve is reduced until an acceptance threshold is reached, which is defined by an acceptable running smoothness or a level of the ignition interventions or permissible lambda deviations of the individual cylinders. Such processes are known from DE 101 56 409 A1, DE 102 59 846 A1 or EP 1 193 381.

It is an object of the invention to improve a control or regulation of an individual internal combustion engine and to specify a corresponding control device. Here, on the one hand a corresponding device of the internal combustion engine to be identified and on the other hand this Device can be individually optimized or improved according to a criterion.

According to the invention, it should be possible to dispense with a cylinder-selective sensor technology or evaluation functionality, wherein it is desirable if the method also works correctly in the case of a malfunction of a lambda probe, a crankshaft position sensor, a vibration sensor or a cylinder pressure sensor. Furthermore, the method should be resistant to aging of the internal combustion engine, d. H. Aging effects of the internal combustion engine or the corresponding device of the internal combustion engine should be permanently compensated reliable. In addition, in application of the invention to a gasoline engine, this at least partially unthrottled operable even at low speeds.

The object of the invention is achieved by a method for the individual operation of an internal combustion engine of a single motor vehicle, according to claim 1; and a control device for an internal combustion engine of a motor vehicle, according to claim 11 dissolved. Advantageous developments of the invention will become apparent from the dependent claims.

According to the invention, such a device is a valve lift adjusting device and a criterion according to the invention a fuel consumption. In this case, according to the invention, a specific internal combustion engine is operated in such a way that its valve lift adjusting device is controlled or regulated such that the fuel consumption of the internal combustion engine is minimized, optimized, reduced or comparatively reduced. The valve lift adjusting device is responsible for the intake and / or exhaust valves of a single, a plurality or all cylinders of the internal combustion engine.

A basic idea of this method is to increase the fuel consumption of the internal combustion engine during driving. to optimize. Ie. The method according to the invention is used as an engine-specific correction method. In this case, the method corrects or adapts or adjusts internal combustion engine-overlapping settings or adjustments of the valve-lift adjusting device that concern a plurality of internal combustion engines. Ie. An existing strategy of controlling or regulating the valve lift adjusting device is adapted individually to the internal combustion engine and to the conditions in which the internal combustion engine is actually operated.

Here, the valve lift adjusting device is controlled or adjusted in particular for small and / or small strokes. Ie. that the preferably at least partially throttled internal combustion engine is idling or an essentially constant and preferably low torque request of a motor vehicle driver is present. The method is preferably carried out at open or at substantially open throttle. However, it is possible to carry out the method even if the throttle valve is partially closed. In this case, the intake valves act as throttle, d. H. the throttle is more than 50% in particular more than 75% and preferably more than 90% open with respect to their cross-section or maximum air flow rate.

The internal combustion engine thus has at least one valve lift adjusting device for at least one valve, the valve lift adjusting device being controlled and / or regulated in such a way that the fuel consumption of this particular internal combustion engine in a given operating point or range is as low as possible or comparatively minimal. This is preferably done with small and / or small strokes of the respective valve (s), in particular of the inlet valve (s). Fuel consumption is preferably a primary criterion of the method. secondary criteria can be B is a smooth running and / or a low vibration of the respective engine concerned.

A primary advantage of the invention is the minimization of the fuel consumption of the internal combustion engine, especially in small and / or small strokes whose valve train, under implicit consideration of manufacturing tolerances and aging effects of the respective internal combustion engine. According to the invention, no cylinder-selective sensor or evaluation functionality, such. B. a cylinder-selective Lambda- recognition or a cylinder-selective engine rotation angle time evaluation, such. As a segment time evaluation or smoother recognition needed. Lambda, smoothness, vibrations o. Ä. Are only indirect variables in terms of the actual goal to set a low-consumption mode of operation of the internal combustion engine. The erfindungemäße method also works when detected malfunction with shutdown of a linear lambda probe, a crankshaft position sensor, a vibration sensor and / or cylinder pressure sensor.

Another advantage is an implicit consideration of a z. B. due to aging of the drive train, for example due to increased crank drive friction, conditional shift of a load or operating point of the engine, the z. B. indicates a higher possible Entdrosselung. Furthermore, the method is not dependent on whether the dynamic properties of a pre-catalyst lambda probe are suitable for a cylinder-specific lambda control. Here are in particular restrictions in a positioning of the linear lambda probe in exhaust gas turbocharger configurations to call what, in particular, systems with not always open to wastegate, such as an overpressure wastegate at low loads concerns.

The method according to the invention can also be carried out before or in particular in time after an adaptation of a fuel metering, in particular an adaptation of injection quantities of one or the fuel injectors. Here- in the adaptation of the injection quantities can be performed at a substantially maximum stroke or a stroke near the maximum stroke of the relevant or relevant valves of the internal combustion engine.

The method is preferably carried out online during operation of the respective internal combustion engine, wherein an adjustable by the valve lift adjusting device stroke of the valve in question is changed, while other, the fuel consumption of this internal combustion engine influencing control variables are kept constant. The stroke of the valve in question, which is modified by the valve lift adjusting device, can be used for a subsequent control of the internal combustion engine if it has been recognized that varying the stroke of the valve has led to an improvement in the fuel consumption of the internal combustion engine.

According to the invention, the values for the lift, which influence the fuel consumption of the internal combustion engine, are varied during the driving operation and the respective, varied values are adopted for the further control of the internal combustion engine, if an improvement of the fuel consumption has been achieved by the variation. Otherwise, the output values of the manipulated variables that existed prior to the variation can continue to be used for the control. Since the optimization already builds on a solid database, the areas within which the strokes are varied are relatively small, so that the optimization for the motor vehicle driver is barely perceptible. The method can be performed individually for each internal combustion engine over its entire service life. As a result, changes in the internal combustion engine over its entire lifetime can be taken into account. In embodiments of the invention, the modified stroke of the valve in question can be stored in a control device, if it was detected that the change in the Hubs of the relevant valve has led to a deterioration of the fuel consumption of the internal combustion engine. This stored stroke of the relevant valve is then no longer adjusted or regulated in the short and / or medium term. In the long term, however, this value can again gain in importance if aging effects, for example due to wear and tear, become effective in the internal combustion engine.

The invention will be explained below with reference to exemplary embodiments with reference to the accompanying drawings near. In the schematic drawing show:

1 shows a motor vehicle with an internal combustion engine and a control device for the internal combustion engine.

Fig. 2 is a schematic diagram of a typical gasoline or

Diesel internal combustion engine;

Fig. 3 fresh air filling differences of the cylinder a

Four-cylinder internal combustion engine with a small or minimum lift of the intake valves;

4 shows the fresh air filling differences from FIG. 3 in FIG

Representation on the lambda hook of a respective combustion;

5 shows an embodiment of a method according to the invention, wherein an online optimization of the valve lift

Adjustment device is shown in the form of a flow chart; and

Fig. 6 is a diagram of a vehicle measurement at idle the

Internal combustion engine, which represents an interaction of fuel consumption as a function of de-throttling.

A motor vehicle 100 of FIG. 1 has a Brennkraftmaschi ne 1 and a control device 26 (engine control unit, engine control electronics) for the internal combustion engine 1. The internal combustion engine 1 is coupled via a drive sträng 112 with drive wheels 114. The control device 26 is coupled via data and signal lines to the internal combustion engine 1. A motor vehicle driver (not shown) can transmit a torque request to the control device 26 via an accelerator pedal 111. The accelerator pedal 111 is associated with an accelerator pedal sensor 113 which detects an actuation degree of the accelerator pedal 111 and transmits it to the control device 26. The greater an amount of accelerator pedal operation by the motor vehicle driver, the greater a requested torque TQI. The control device 26 controls the internal combustion engine 1 via the data and signal lines in such a way that the torque TQI generated by the internal combustion engine 1 corresponds to the torque request of the motor vehicle driver. 2 shows a greatly simplified embodiment of the internal combustion engine 1, which has at least one cylinder 2 and a piston 3 movable up and down in the cylinder 2. The internal combustion engine 1 further comprises an intake tract 40, in which an air mass sensor 5, a throttle valve 6, a swirl flap 31 for influencing the intake flow and a suction pipe 7 are arranged downstream of an intake opening 4 for sucking in fresh air. The intake tract 40 opens into a combustion space 30 delimited by the cylinder 2 and the piston 3. The fresh air required for combustion is introduced into the combustion space 30 via the intake tract 40, the fresh air supply being controlled by opening and closing an intake valve 8.

The internal combustion engine 1 shown here is an internal combustion engine 1 with direct fuel injection, in which the fuel required for the combustion is injected directly into the combustion chamber 30 via a fuel injector 9. The combustion exhaust gases are discharged via an exhaust valve 11 into an exhaust gas tract 16 of the internal combustion engine 1 and by means of a arranged in the exhaust gas duct 16 exhaust gas catalyst 12 cleaned. In the exhaust tract 16 is also a controllable exhaust flap 33rd

A power transmission to the drive train 112 (see Fig. 1) via a coupled to the piston 3 crankshaft 13. The internal combustion engine 1 further has a speed sensor 15 for detecting the rotational speed of the crankshaft

13 and a combustion chamber pressure sensor 32 for detecting the pressure in the combustion chamber 30. The combustion chamber pressure sensor 32, which may also be integrated in the spark plug 8, provides a high-resolution signal which the current pressure in the combustion chamber 30 during the intake stroke, the compression stroke, the power stroke and the exhaust stroke. The intake valves 8 and / or exhaust valves 11 preferably each have a controllable and / or controllable valve lift adjusting device 50, by means of which the valve opening times or the valve lifts can be varied. In this case, it is possible to set the temporal overlap of the opening periods of the intake valve or valves 8 and of the exhaust valve or exhaust valves 11 per combustion chamber 30. As a result, both the filling of the combustion chambers 30 with fresh air or with exhaust gas (internal exhaust gas recirculation) and the gas exchange work can be influenced. The respective valve lift adjusting device 50 can be realized for example by a hydraulically adjustable camshaft or an electromagnetic valve drive.

A single valve lift adjusting device 50 can influence one, a plurality or all of the relevant intake valves 8 or exhaust valves 11 accordingly. Here, it is preferred that the valve lift adjusting device 50 is used instead of or in addition to the throttle valve 6 to throttle the intake fresh air and a entering into the combustion chamber 30 air mass or quantity MAF (Mass Air Flow) depending on a request of the motor vehicle driver or depending on the operating conditions of the internal combustion engine 1 to meter. In particular, it is preferable to actuate the valve-lift adjusting device 50 in such a way that a de-throttled operation of the internal combustion engine 1 is possible, ie the throttle valve 6 is open wide or at most wide. A slightly closed throttle 6 for effective tank ventilation (not shown) should be disregarded here. Of course, it is also possible to close the throttle valve 6 up to a certain amount and the final throttling of the passing fresh air by means of

Valve Stroke adjusting device 50 adjustable inlet valves 8 to leave. However, it is preferred that the intake valves 8 and thus the valve lift adjusting device 50 of the intake valves 8 assume the throttling function. Ie. On the one hand, the combustion chambers 30 can be filled with fresh air of maximum density, which, on the other hand, can be realized for each operating point of the internal combustion engine 1 with a respective smallest valve lift. The internal combustion engine 1 further has a fuel supply system, which has a fuel tank 17 and a fuel pump 18 preferably arranged therein. The fuel is supplied by means of the fuel pump 18 via a supply line 19 to a pressure accumulator 20. This is a common accumulator 20, from which the fuel injectors 9 are supplied for several cylinders 2 with pressurized fuel. In the supply line 19, a high-pressure pump 22 is further arranged. The high-pressure pump 22 serves to supply the fuel delivered by the fuel pump 18 at relatively low pressure (about 3-5 bar) to the pressure accumulator 20 at high pressure (typically up to 200 bar in the case of petrol engines and up to more than 2,000 in the case of diesel engines ). At the pressure accumulator 20, a pressure sensor 34 for detecting the pressure in the pressure accumulator 20 is further arranged. The accumulator 20 may, for. B. be formed in a diesel engine as a common rail. The internal combustion engine 1 is associated with the control device 26, which is connected via signal and data lines with preferably all actuators and sensors of the internal combustion engine 1. In particular, the control device 26 via the data and signal lines to the fuel pump 18, the air mass sensor 5, the combustion chamber pressure sensor 32, the throttle valve 6, the swirl flap 31, the spark plug 10, the fuel injectors 9, the valve lift / the adjusting devices 50 of the intake valves 8 and / or the exhaust valves 11, the exhaust valve 33, the pressure sensor 34 and the speed sensor 15 coupled. The controller 26 is therefore possible to vary by transmitting appropriate control signals, all variables and operating parameters, which, for. B. TQI torque and efficiency of the internal combustion engine 1 influence.

In the control device 26, code-based engine control functions (KF1 to KF5) are implemented in the form of software. In particular, a torque torque model is implemented in the control device 26 which, based on the sensor variables, models the torque TQI currently produced by the internal combustion engine 1. By means of the torque model, the actuators and manipulated variables of the internal combustion engine 1, such as the positions of the throttle valve 6, the swirl flap 31 and the exhaust valve 33, the ignition timing of the spark plugs 10, and the opening periods or strokes of the intake and / or exhaust valves 8, 11th via the valve lift adjusting devices 50 and the fuel injectors 9, in such a way that a specific, predetermined torque TQI is produced by the internal combustion engine 1.

In the normal case, the torque TQI of the internal combustion engine 1 is adjusted such that it corresponds to the torque request of the motor vehicle driver. For this purpose, a motor-specific database is stored in the control device 26, which is stored, for example in the form of conditioned maps and constants in the control device 26. The database is obtained for example by test series on test benches or during test drives. The execution of these test series and test drives, however, takes place on a very limited number of internal combustion engines. Nevertheless, the data obtained is generally used for all internal combustion engines of the respective type. Due to manufacturing tolerances or changes over the lifetime occur on each internal combustion engine 1 individual changes, so that the general database in terms of efficiency, the fuel consumption, emissions, etc. is not always an optimum or maximum / minimum or local maximum / minimum ,

When filling the cylinders A, B, C, D (see FIG. 3) of the internal combustion engine 1 with fresh air, differences in the results arise, in particular due to manufacturing tolerances of the valve lift adjusting device 50 or the variable valve lifting system 50, especially in the case of small and microstrokes respective air-fuel mixtures and the respective generated torques of the cylinders A, B, C, D, which leads to a deterioration of the smoothness of the internal combustion engine 1. Low lift is used when the stroke of the intake 8 or exhaust valve 11 -S is about 3 mm, the minimum lift is stored in the control device 26 according to the invention optimized minimum valve VLFT_MIN, which is usually greater than the minimum possible mechanical valve lift. In FIG. 3, the cylinders A, B have a positive and the cylinders C, D a negative tolerance in a valve lift VLFT of the intake valves 8.

In the case of the positive tolerance, this leads to an above-average and, with the negative tolerance, to a below-average filling of the respective cylinders A, B; C, D with respect to a calculated by the controller 26 setpoint of a cylinder filling with fresh air MAF_SOLL. As a result, differences in the fillings of the cylinders A, B, C, D in the case of small and / or minimum stroke are in practice well within ± 10% of the global or average or desired air mass MAF_SOLL. As a result of the differences in the filling with fresh air, the torques TQI of the cylinders A, B, C, D are formed at different positions of the lambda hooks, which is shown in FIG. The cylinder-specific lambda differences can be adjusted again in the control device 26 via a "lambda balancing" function, see the arrows in FIG. 4. Such lambda balancing can have an effect in further increased differences in the cylinder-individual torques , which may result in a further deterioration of smoothness.

In the prior art, this uneven running caused by the different cylinder torques TQI is improved by means of opposite ignition angle interventions. However, this results in turn, depending on the cylinder operating point disadvantages. If the cylinder, as in the example of FIG. 4, the cylinders A, B, characterized by a higher fresh air mass calculated by the controller 26, he will also generate too high a torque TQI, especially if he already has a lambda correction has experienced. This excessively high torque TQI is changed by the ignition angle correction in a subsequent combustion with true torque TQI but for higher exhaust gas temperature, lower efficiency and also increased consumption.

These increasing disadvantages are counteracted by savings in throttle losses due to the operation of the internal combustion engine 1 with small valve strokes VLFT. Even without ignition angle interventions by running smoothness optimization cause filling differences in

Small and Kleisthubbereich the intake valves 8 a suboptimal operating point. Ie. that the filling differences due to the manufacturing tolerances at small and small lift of the intake valves 8, a fuel-saving potential in the valve lift adjusting device 50 limit. According to the invention, a consumption of fuel is used as a reference variable for an optimization strategy, in particular for small and minimum strokes of the inlet valves 8, wherein the valve lift adjusting device 50 is controlled or adjusted accordingly. In addition to a low or optimized fuel consumption results in a reduction of emissions of carbon dioxide and possibly an improvement in efficiency. Ie. Also, that the optimization strategy according to the invention also a good efficiency of the internal combustion engine 1 is realized at a low or actual as minimal as possible or extremely comparable as minimum fuel consumption.

According to the invention, the consumption of fuel is considered to be an essential or a major input of a

Control and / or regulation of the valve lift adjusting device 50 used, and not as usual, the comfort criterion quiet running. In a given operating state of the internal combustion engine 1, an online optimization of a minimum lift VLFT_MIN of the inlet valves 8 in FIG

Direction of minimum or minimized or lower or lower or optimized fuel consumption. This is preferably done according to the German patent application with the file number 10 2008 052 323.2, the contents of which should be included here in full. Corresponding points of contact with this document also emerge from the following remarks. Furthermore, the invention can also be transferred to the exhaust valves 11 of the internal combustion engine 1. Implementations within the meaning of the invention are preferably all

Control and / or regulating mechanisms having the following characteristics. An input variable is the fuel consumption or a variable that allows a conclusion on the fuel consumption, such. An output or manipulated variable is the stroke VLFT of the relevant valve 8, 11. An adaptation algorithm controls the stroke VLFT the valve 8, 11 at operating points with small and / or smallest air filling to a minimum of the input variable; So the minimum for the relevant valve 8, 11 stroke VLFT_MIN. In a further development of the invention, a first adaptation value is determined in a first adaptation process in a throttled operating state of the internal combustion engine 1 at a maximum stroke VLFT_MAX of the valve or valves 8, 11. This adaptation value is based on the consideration that in this operating state lambda differences are due to tolerances in the fuel metering, in particular due to the fuel injectors 9, the fuel metering of the cylinders 2 being adjusted accordingly. With this first adaptation, an adaptation in the manner described above in the direction of minimum fuel consumption is carried out in a second adaptation step in the case of small and minimum lift VLFT_MIN of the valve drive. This can also be reversed according to the invention, ie first an adaptation of the stroke VLFT of the valves 8, 11 and then an adaptation of the fuel metering.

5 shows an embodiment of the method as an online optimization of the fuel consumption or as an online optimization of a control of the valve lift Verstelleinrich- device 50, in particular the valve lift adjusting device 50 of the intake valves 8 of the internal combustion engine 1 during operation of the internal combustion engine 1 is shown in the form of a flow chart. By means of the method according to the invention, the fuel consumption or the activation of the valve lift adjusting device 50 of an internal combustion engine 1 can be optimized or improved individually over the entire operating time of the internal combustion engine 1.

The method is started with step 200, for example after starting the internal combustion engine 1. Advantageously, it is then checked in a step 201 whether the requirements for a minimum or minimum stroke of lass valves 8 are present, that is, whether the valve lift adjusting device 50 is to implement corresponding strokes of the inlet valve or valves 8. This is the case in particular for the idling of the internal combustion engine 1 or even in the case of a low torque requirement, which is preferably constant over a certain period of time. Furthermore, it is preferred that the internal combustion engine 1 is operated in a substantially defrosted or only slightly throttled state. In this case, a corresponding query can be made in step 201. However, it is also possible to carry out the method according to the invention with a more closed throttle valve 6.

A substantially constant torque request of the motor vehicle driver can be recognized, for example, when the pedal value of the accelerator pedal 111 of the motor vehicle is within a predetermined tolerance band over a specific period of time. The pedal value of the accelerator pedal 111, which is detected by the pedal sensor 113, indicates how far the motor vehicle driver has passed the accelerator pedal 111. If the result of the query in step 201 is negative, the query is repeated. The method according to the invention is applicable in particular when the following method steps are carried out at idling or an essentially constant torque request of the motor vehicle driver, since this has so far produced the best results.

However, depending on the valve lift adjusting device 50, this can only be applied to a single or a plurality of intake valves 8 of the internal combustion engine 1. If the result of the query in step 201 is positive, the method continues with step 202, in which the lift VLFT_MIN, in particular the minimum or minimum lift of the intake valve 8, is varied. The remaining control variables of the internal combustion engine 1, which have an influence on the fuel consumption. sit, are kept constant. The variation of the lift VLFT_MIN of the intake valve 8 can be effected, for example, by increasing or decreasing the value (s) by a predetermined amount. This amount of change is preferred to be chosen such that it is neither to component damage nor greater loss of comfort for the motor vehicle driver, z. B. by a sudden change in torque comes. After the variation of the lift VLFT_MIN of the intake valve 8 in step 202, the method proceeds to step 203, in which it is checked whether an improvement of the fuel consumption of the internal combustion engine 1 is recognizable due to the new lift VLFT_MIN of the intake valve 8. This can be realized, for example, by determining a variable before and after the variation of the manipulated variable which allows a conclusion to the current fuel consumption of the internal combustion engine 1. The value of the determined variable therefore represents a measure of the current fuel consumption of the internal combustion engine 1. Advantageously, this variable is a specific fuel consumption (consumed fuel quantity per kilowatt hour)

[g / KWh]). An amount of fuel supplied and the specific fuel consumption may be determined based on the injection pressure detected by the pressure sensor 34 and the timings of the fuel injectors 9. An improvement of the fuel consumption of the internal combustion engine 1 can be done for example by comparing the size before and after the variation of the manipulated variable. An improvement of the fuel consumption of the internal combustion engine 1 is z. B. detected when the specific fuel consumption, the injected fuel quantity or the work performed by the internal combustion engine during the gas exchange work is less than before the variation of the manipulated variable. An improvement in fuel consumption is also possible if the indi- decorated medium pressure; or the indicated maximum pressure after the variation of the lift VLFT_MIN of the intake valve 8 is greater than before. If the result of the query in step 203 is positive, ie if an improvement in the fuel consumption of the internal combustion engine 1 is detected by the variation of the lift VLFT_MIN of the intake valve 8, the method proceeds to step 204 in which the modified value of the lift VLFT_MIN is stored and is used for further operation of the internal combustion engine 1.

If the result of the query is negative in step 203, d. H. If no improvement in fuel consumption is detected after changing the lift VLFT_MIN of the intake valve 8, the method continues with step 205, in which the current, changed value of the lift VLFT_MIN is stored. This value is no longer used for the operation of the internal combustion engine 1 and for further optimization in the short or medium term. In the long term, this value can be z. B. become interesting again due to aging processes. This should be taken into account accordingly.

The method then proceeds to step 206 where the current value of the lift VLFT_MIN of the intake valve 8 relevant to the operation of the internal combustion engine 1 is set to the initial value, i. H. to the last value before the variation of the VLFT_MIN, is reset. For the further driving operation or operation of the internal combustion engine 1, therefore, the output value is used.

Subsequent to step 204 or step 206, the method proceeds to step 207, in which it is checked whether a predetermined condition for canceling the optimization of the stroke VLFT_MIN of the intake valve 8 is satisfied. The condition may, for example, be met if, by optimizing the lift VLFT_MIN of the intake valve 8, an improvement fuel consumption and after further variation of the VLFT_MIN stroke a stagnation or deterioration of fuel consumption is detected. In this case, an optimum or a minimum of the lift VLFT_MIN of the intake valve 8 has already been determined. For example, the condition may be met even if neither decreasing nor increasing the lift VLFT_MIN resulted in improving fuel economy. In this case, the optimal value for the VLFT_MIN stroke was already before the beginning of the variation.

If the result of the query is positive in step 207, d. H. the condition for canceling the optimization of the hub

VLFT_MIN of the inlet valve 8 is satisfied, the method ends in step 208 or continues thereafter, wherein z. B. can be changed to another manipulated variable to be optimized, since a further variation of the stroke VLFT_MIN the intake valve 8 is not useful. Ie. Subsequently, a variation of another manipulated variable is started. Such another control variable can, for. An indexed average pressure, an injected fuel amount, an indicated maximum pressure, a position of a combustion center, an operation performed by the internal combustion engine during a gas exchange, an ignition timing, a start / end of the fuel injection, an efficiency, a position of the swirl door 31 and or a position of an exhaust flap 33 be.

In the case of a negative result of the query in step 207, in the case of the previous variation of the stroke

VLFT_MIN of the intake valve 8 was detected, the direction of the variation, ie increase or decrease in the value of the lift VLFT_MIN of the intake valve 8, maintained and the variation of the same control variable continued with step 201. In the case where the previously performed variation of the lift VLFT_MIN of the intake valve 8 does not improve the fuel consumption caused, the direction of the variation is changed, for. For example, increasing the value of the lift VLFT_MIN of the intake valve 8 to a decrease in the value of the stroke

VLFT_MIN of the intake valve 8 changed and the variation continued with step 202.

It should be noted that during the course of the process, the torque request of the motor vehicle driver is constantly monitored. In the moment in which a change in the torque request of the motor vehicle driver is detected, the variation of the lift VLFT_MIN of the intake valve 8 is interrupted and the method jumps to step 201. This ensures that there are no overlaps of the measures carried out during the process and the normal control of the internal combustion engine 1 comes. According to the invention, this method is also applicable analogously to the exhaust valve or valves 11.

FIG. 6 shows a diagram of a vehicle measurement at idle with an idling speed of approximately 810 revolutions per

Minute, with an interaction of fuel consumption in

Dependence on the Entdros drove is shown. Of the

Fuel consumption drops from about 9.5mg / st (st: stroke, ie.

Single injection) with a valve lift VLFT from 3mm to approx. 7,5mg / st with a valve lift VLFT of approx. 0,5mm, and thus shows clearly an improvement of the fuel consumption and also the efficiency by de-throttling.

As the valve lift VLFT decreases, the degree of dethrottling increases, which is particularly evident at the intake manifold pressure MAP, which rises to a maximum value of approximately 940 hPa due to the opening of the throttle valve 6. At an intake manifold pressure of approx.

50hPa below ambient pressure, the Entdrosselung is completed, the fresh air can fill the cylinder 2 with maximum density. The degree of delivery and thus the development of the torque TQI is now completely controlled or regulated via the valve train - the so-called unthrottled operation. The method according to the invention is therefore of course also applicable to a method for the individual operation of only one valve lift adjusting device of a respective internal combustion engine. Ie. Furthermore, more generally that the inven tion is also applicable to a method for Hubadaption, in particular egg ner Kleinsthubadaption, a variable valve lift or a valve lift adjusting device.

Claims

claims

1. A method for the individual operation of an internal combustion engine (1) of a single motor vehicle (100), wherein the

Internal combustion engine (1) at least one valve lift adjusting device (50) for at least one valve (8, 11), and the valve lift adjusting device (50) is controlled / regulated such that a fuel consumption of said internal combustion engine (1) in a given Operating point is low or comparatively low.

2. The method according to claim 1, wherein the valve lift adjusting device (50) for small and / or small strokes of the valve (8, 11) according to the criterion as low as possible or comparatively low fuel consumption of this internal combustion engine (1) controlled / regulated becomes.

3. The method according to claim 1 or 2, wherein the method is performed in a de-throttled or a substantially throttled, or a slightly to moderately throttled state of an intake tract (40) of this internal combustion engine (1).

4. The method according to any one of claims 1 to 3, wherein the

Fuel consumption of this internal combustion engine (1) is a primary criterion of the method, and a secondary criterion of the method is preferably a quiet running and / or low vibration of this internal combustion engine (1).

5. The method according to any one of claims 1 to 4, wherein the method is carried out before or preferably in time after an adaptation of a fuel metering, in particular an adaptation of injection quantities of a fuel injector (9), wherein the adaptation of the injection quantities is preferably carried out at a substantially maximum lift (VLFT_MAX) of the valve (8, 11) of the internal combustion engine (1).

6. The method according to any one of claims 1 to 5, wherein the method during an operation of this internal combustion engine (1) is performed, and by the valve lift adjusting device (50) adjustable stroke (VLFT) of the valve (8, 11) is varied, while others, the fuel consumption of this internal combustion engine (1) influencing manipulated variables are kept constant.

7. The method according to any one of claims 1 to 6, wherein the varied by the valve lift adjusting device (50) stroke (VLFT) of the valve (8, 11) is used for a timely control of the internal combustion engine (1), if detected is that the change of the stroke (VLFT) of the valve (8, 11) has led to an improvement of the fuel consumption of the internal combustion engine (1).

8. The method according to any one of claims 1 to 7, wherein the method is performed when the internal combustion engine (1) is idling or a substantially constant and preferably low torque request of a motor vehicle driver is detected.

9. The method according to any one of claims 1 to 8, wherein the modified stroke (VLFT) of the valve (8, 11) in a control device (26) is stored, if it is detected that the change of the stroke (VLFT) of the valve (8 , 11) has led to a deterioration of the fuel consumption of the internal combustion engine (1), and this stored stroke (VLFT) of the valve (8, 11) is no longer adjusted in the short and / or medium term.

10. The method according to any one of claims 1 to 9, wherein the method as an engine-individual Korrek- is applied, which corrects or adapts internal combustion engine-comprehensive settings or Einregelungen the valve lift adjusting device (50).

11. Control device for an internal combustion engine (1) of a motor vehicle (100), which is designed such that by the control device (26), a method according to one of claims 1 to 10 is feasible and / or performed.