DE10025495B4 - Method for operating an internal combustion engine - Google Patents

Abstract

Method for operating an internal combustion engine, in which, as a function of acting on the internal combustion engine Vorgabelast (t _{l, soll} ) determines a target pressure (p _{s, soll} ) in the intake manifold of the internal combustion engine and adjusted via an air supply device for the supply of combustion air to the cylinders of the internal combustion engine is, wherein the ignition timing, the beginning of the injection and the duration of the injection according to a predetermined relationship depending on the Vorgabelast (t _{l, should} ) determined and supplied as a control signal actuators over which the ignition or the injection are set, characterized in that, during stationary operation of the internal combustion engine, a mean injection duration (t _{i, mw} ) is determined, from which an average load variable (t _{1, is} ) is determined, which is compared with the current feed load (t _{1, soll} ), the difference between Pre-load (t _{l, soll} ) and average load size (t _{l, is} ) in the determination vo n ignition timing, start of injection and duration of injection is taken into account.

Description

The The invention relates to a method for operating an internal combustion engine according to the preamble of claim 1.

From the publication DE 195 30 274 A1 a method for controlling an internal combustion engine with fully variable valve train is known, which opens the possibility to control the opening and closing times of the gas exchange valves independently. In this method, from a torque request to the engine - for example, triggered by the current accelerator pedal position - a desired filling information obtained for the cylinders to be supplied air mass, which is used on the one hand for driving a valve control unit and on the other hand for the control of injection and ignition as load information.

Out the torque request or the accelerator pedal position can be a coarse adjustment specified for the air ratio become. For fine adjustment of the air ratio, however, an air measurement must be taken into account which is either over a lambda probe or over an air mass meter is obtained. From the measured value can a Correction factor can be determined, which is a precise adjustment of the metered Air volume permitted.

The Fine adjustment sets a measurement of the oxygen content or the Air mass ahead. Abrupt changes the pre-load is - if necessary considering the inertia of the Measuring element - in a sudden change the Luftzu drove converted. This can be a disharmony Set the response.

Of the Invention is based on the problem, the response of To improve internal combustion engines in response to load changes.

This Problem is inventively with the Characteristics of claim 1 solved.

According to the novel Procedure is provided that both the ignition and the injection determining parameters such as ignition timing, Start of injection and duration of injection as a function of pre-load be determined, which in particular of the accelerator pedal position as well if necessary, from manipulated variables of a Depend on the driving dynamics control program. This the ignition and the injection determining parameters become common already for determines the determination of the amount of air to be supplied to the internal combustion engine and are thus available in the engine control or regulation. Of the ignition timing, the beginning of the injection and the duration of the injection supplied as actuating signals to actuators, via which the ignition and the injection is carried out become.

According to this Method is it possible both the air side and the fuel side of an internal combustion engine via a common parameters - the Pre-load - to adjust. You get hereby a simpler construction of engine control and regulation and also the units used in the internal combustion engine, there over a common parameters both the air supply and the fuel supply or the ignition be managed.

in the stationary operation the internal combustion engine is determined a mean injection duration, the above a proportional factor is converted into an average load size, which is compared with the current default load. The difference the current default load and the average load size for ignition and Injection and in particular also considered for the air supply. This achieves the effect of making sudden changes the advance fork no sudden effect on ignition, injection and air supply, but rather be passed smoothly, whereby overall a more harmonious response of the internal combustion engine is reached.

One Air mass meter or a similar measuring element is no longer needed in the intake tract, whereby messbedingte delays eliminated. The internal combustion engine can therefore be faster on load changes react, mixture formation errors are reduced. corrections in the case of a deviation from the stoichiometric Air-fuel ratio can optionally via the lambda control can be compensated. In addition, can also be an engine knock control be provided over the one damaging Engine knock is prevented by influencing the ignition timing.

The novel method is preferably used in internal combustion engines, which have an adjustable air supply device for the supply of combustion air to the cylinders, in particular adjustable gas exchange valves or both adjustable gas exchange valves and a throttle valve, and are also equipped with a motor control and control unit, in which depending on the operating condition of the internal combustion engine characterizing input signals are generated in accordance with stored regulations or maps actuating signals, the actuators the internal combustion engine, in particular for the ignition and the injection and the air supply means, are supplied. There are advantageously used electromag netic, variably adjustable gas exchange valves; In addition, however, mechanically adjustable gas exchange valves come into question.

In an appropriate training it is envisaged that the ignition timing, the start of injection and the duration of injection in dependence from outside pressure and outside temperature be determined to the supplied to the combustion chambers air volumes to the adapt to current environmental conditions.

Further Advantages and expedient designs are the further claims, the figure description and the drawings. Show it:

1 the structure of an engine control and regulation system for setting the ignition and the injection as a function of the given load,

2 a function block with an adaptation function for averaging the parameters relating to the ignition and the injection in stationary operation,

3 a function block with a function for taking into account ambient pressure and ambient temperature,

4 a function block with a function for determining correction variables in the case of differing state variables in different cylinder banks of an internal combustion engine,

5 a functional block having a function for determining the desired valve lift corresponding to the preliminary load,

6 a function block with a function for determining the desired position of the throttle body in the intake tract of the internal combustion engine,

7 a function block with a function for taking into account dynamic effects in the ignition and the injection in the non-stationary operation of the internal combustion engine,

8th a flowchart for predictive load control in an internal combustion engine with variable valve lift.

1 shows a schematic representation of the structure of an engine control and regulation for the metering of combustion air and the determination of the associated ignition data and injection data, wherein the amount of combustion air both via a throttle body, in particular a throttle valve in the intake tract and via variably adjustable gas exchange valves, which via VLC Have to be adjusted. In the engine control and regulation MS, the preliminary load t _{1, soll} is first determined, which can be displayed as a function of the accelerator pedal position and optionally of further variables, in particular the current slope. The Vorgabelast t _{l, should} also depend on variables of a driving dynamics control program.

The Vorgabelast t _{l, shall} is first supplied to a functional block TLA, which includes an adaptation function for averaging the parameters relating to the ignition and the injection in steady-state operation. In function block TLA, a correction load dt _{1 is} determined as a function of predischarge load t _{1, soll} and a mean injection duration t _{i, mw} , which correction element is supplied to a further function block TLDK.

In the function block TLDK, an environmental compensation takes place in that the preliminary load t _1, o is first of all taken into consideration of the ambient pressure p _a and taking into account the ambient temperature T _a to standardized pressure and temperature values p _{a, 0} , T _{a, 0} . In the function block TLDK, the correction load dt ₁ is also considered additively. At the output of the function block TDLK is a value for the target air volume t _{l, mot} , which corresponds to the Vorgabelast t _{l, should} take into account the environmental conditions and the correction load. The target air volume t _{l, mot} ignition and injection _parameters t _{l, tizw} (target load for ignition and injection) are assigned.

The desired air volume t _{1, mot} is first supplied to a function block TLVEN, in which the valve lift for the variably adjustable gas exchange valves of the internal combustion engine is determined as a function of the air volume t _{1, mot} . In the exemplary embodiment, the internal combustion engine to have two separately controllable cylinder banks, each cylinder bank gas exchange valves are assigned, the stroke is adjustable. Following this structure, in the function block TLVEN, different values vh _{soll, b1} and vh _{soll, b2 are} generated for the set valve lift of the gas exchange valves of the first and second cylinder banks of the internal combustion engine. Here, correction valve lifts dvh _b1 , dvh _b2 from a bank equalization function block BGS, in which different values for the valve lifts of different cylinder banks are made equal to a mean value, are taken into consideration.

The set valve lift vh _{should, b1} and vh set _{, b2} is set as the setpoint to a VLC controller, over which the valve lift of the gas exchange valves manipulated who that can, fed.

Possibly can also more than two cylinder banks be provided with separately adjustable gas exchange valves.

ever after, in which operating range the internal combustion engine operated It may be necessary, in addition to or as an alternative to Setting the gas exchange valves and a throttle body, in particular a throttle to operate in the intake manifold of the internal combustion engine to which corresponds to the current operating state of the internal combustion engine To adjust the amount of combustion air. The actuation of the Throttle valve is required especially in operating areas in which the target intake pressure below the atmospheric pressure lies; In this case, a vacuum must be generated in the intake manifold be, what by an appropriate positioning of the throttle can be accomplished.

The throttle valve is assigned a function block TLVDK, via which the throttle flap _is controlled as a function of the valve lift vh _soll . The valve lift vh _{is intended to} represent an average of the valve lift quantities vh _{soll, b1} and vh _{soll, b2 of} the left and right cylinder bank of the internal combustion engine. From the averaged valve lift vh _is a value for the throttle position angle sw is determined in the function block TLVDK, which is supplied to a throttle valve actuator for adjusting the throttle.

In addition to the setting of the gas exchange valves and, if appropriate, the throttle flap, the ignition timing, the start of injection and the injection _{duration are} determined as a function of the preliminary load t _{1, tizw} in a further functional block _TLDYN . The target air mass t _{l, shall} be assigned ignition and injection _parameters t _{l, tizw} , which are further processed in the function block TLDYN. The functional block TLDYN is also supplied with the setpoint and actual variables vh _soll and vh _{ist of} the valve lift, which are present at the output of the valves assigned function block TLVEN or in the VLC controller of the gas exchange valves.

in the Function block TLDYN compensates for effects that are in non-stationary mode occur. These effects can come through to the fact that both the throttle and the steller for the gas exchange valves have finite positioning times, which in dynamic transition areas can lead to deviations between the setpoints and the actual values. These deviations can affect the amount of air in the cylinders, the must accordingly the ignition and injection parameters adapted to the actual amount of air become. This adaptation is carried out in the function block TLDYN.

After adaptation to the instationary operation in the function block TLDYN, the adapted ignition and injection _parameters t _{izw are supplied to} the actuators for the ignition and the injection, the ignition timing of the injection start and the injection duration are set as a function of the predischarge load taking into account transient influences.

In the 2 to 7 the functional blocks of the engine control and regulation MS are shown in detail.

2 shows the function block TLA, in which an averaging of the parameters relating to the ignition and the injection is carried out in stationary mode. The function block TLA are supplied as input variables, the Vorgabelast t _{l, soll} and the average injection duration t _{i, mw} . The average injection duration t _{i, mw} is first converted into the actual load t ₁ , which corresponds to the actual air mass in the cylinder, by application of a λ factor. It is the difference of Vorgabelast t _{l, soll} and actual load t _{l is} formed and filtered this difference in a low-pass filter in which frequencies above half a low-pass cutoff frequency to obtain a smoothed Wertverlauf. After the low-pass filtering, integration takes place in an integrator element. At the output of the integrator member is the correction load dt _l , over which the difference between Vorgabelast t _{l, soll} and Istlast t _{l, is} balanced. The correction load dt ₁ is supplied to the functional element TLDK, in which consideration of ambient pressure and ambient temperature takes place.

In 3 the function block TLDK for the consideration of ambient pressure and ambient temperature is shown in detail. On the Vorgabelast t _{l, soll} the correction load dt _{l is added} from the function block TLA. The sum of preset load t _{L, should not} and correcting load dt _l is with an environmental correction factor f _{corr, U} is multiplied, which in dependence on the actual outside temperature T _a, the current external pressure p _a and normalized in response to sizes of pressure and temperature, P _{A , 0} and T _{a, 0} according to the relationship f corr, U = p a, 0 / p a * T a / d a, 0 let represent. By multiplying by the correction factor f _{korr, U} , the preliminary load is related to the normalized pressure and temperature quantities p _{a, 0} and T _{a, 0} . As a result of the multiplication, one obtains the setpoint air volume t _{1, mot} , which is present at the output of the function block TLDK and is supplied to the further function blocks.

From the desired air mass t _{l, shall} also ignition and injection _parameters t _{l, tizw} determined.

In 4 the function block for bank equalization or bank equalization BGS is shown, in which the state variables of different cylinder banks of an internal combustion engine are adjusted to common values. In the bank equivalent circuit BGS shown in the exemplary embodiment, the state variables of two cylinder banks of an internal combustion engine are matched to one another; However, embodiments are also conceivable in which more than two cylinder banks of an internal combustion engine are to be considered.

Bank equalization BGS is fed with bank-selective injection times t _{i, b1} and t _{i, b2} , which are each assigned to a cylinder bank, as input variables. From the bank-selective injection times t _{i, b1} and t _{i, b2} , the difference is formed, which is fed to a low-pass filter to filter out frequencies below the low-pass cutoff frequency and to obtain a smoothed value curve. Subsequent to the low-pass filtering, integration takes place in integrator elements, wherein a positive value dvh _b2 for the correction valve lift is fed to that cylinder bank whose bank-selective injection time t _i, b 2 has been subtracted at the input of the function block, whereas that bank whose bank-selective injection time t _{i, b1 is} positive at the input of the function block, a negative value dvh _{b1 is} supplied for the correction valve lift. Due to this sign reversal, a matching is achieved at a common average value by the deviating from a mean values of bank selective injection times t _i, t _{i b1} and _be compensated for by an opposite correction element _b2.

5 shows a detailed representation of the function block TLVEN for determining the target valve lift vh _{soll, b1} and vh _{soll, b2} for each cylinder bank of the internal combustion engine. The desired air volume t _{1, mot} and the engine speed n _{ist are} supplied to the function block TLVEN as input variables. In characteristic maps of the function block TLVEN, a mean valve lift control value vh _s and a mean valve lift correction value dvh _{s are} determined as a function of engine speed, based on the desired air volume t _{1, mot} . The correction value dvh _s is firstly subtracted from the manipulated variable vh _s , whereby a provisional target valve lift vh _{s, b1} for the first cylinder bank is achieved, and secondly the correction value dvh _{s is added} to the manipulated variable vh _s , whereby a second, provisional target value is added -Ventilhub vh _{s, b2 is achieved} for the second cylinder bank. The correction valve lift dvh _b1 or dvh _b2 assigned to the respective cylinder bank is added to the provisional nominal valve lifts vh _{s, b1} and vh _{s, b2} ; the correction valve lifts dvh _b1 and dvh _b2 for the first and the second cylinder bank respectively are located in the bank equalization block BGS () preceding the valve switching function block TLVEN (FIG. 4 ).

From the addition of the provisional nominal valve strokes vh _{s, b1} and vh _{s, b2} with the associated correction valve strokes dvh _b1 and dvh _b2 , the final target valve strokes vh _{soll, b1} and vh _{soll, b2} for the gas exchange valves of the first or the first gas valve The second cylinder bank is calculated. In addition, it is expedient to use the two desired valve strokes vh _{soll, b1} and vh _{soll, b2 to} calculate an average value vh _soll .

In 6 the operation of the function block TLVDK is shown, which includes the structure of the throttle valve control. The function block TLVDK is used as input in the function block TLVEN ( 5 ) Mean determined vh _to for valve lift together with the engine speed n _is supplied. From this, a target pressure quotient is formed, which is multiplied by the current external pressure p _a to obtain a target pressure p _{s, soll} . The setpoint pressure p _{s, is to} be divided in a first branch of the function block TLVDK by the value of the current external pressure p _a and fed to a characteristic which ensures a maximum regulator limit sw _{r, max} for the throttle angle.

The setpoint pressure p _{s, soll} is also in a further branch of the function block TLVDK with the actual prevailing in the intake manifold actual pressure p _{s, is} compared, the difference between the target and actual pressure in the intake manifold is fed as input to a PI controller. The controller output sw _{r of} the PI controller is limited to the controller limitation sw _{r, max} .

In the further course of the controller output determined is sw _r sw to a pilot control value _v added the throttle back angle, wherein the pilot control value sw _v from a characteristic diagram as a function of the desired valve stroke vh _{is intended} and the engine speed _is n is determined. The resulting throttle angle sw is to be supplied to a throttle valve actuator.

In 7 is a function block TLDYN to account for dynamic effects in the ignition and the injection in the stationary operation of the internal combustion engine shown. The function block TLDYN be as input variables, the values for the actual actual valve lift _is vh and the target valve lift vh _{is to} fed, from which a difference dvh is formed _dyn, the actual valve lift _is vh conveniently tapped from the VLC controller of the gas exchange valves becomes. The differential valve lift dvh _dyn is multiplied by a gradient, which is calculated from the division of a load change Δt _l with a valve lift change Δvh, wherein the Lastän alteration .DELTA.t _l of two temporally successive loads default t _l, is determined and the valve lift AVH the temporal change of successive target valve lift _to vh referred _to. From the multiplication of the differential valve lift dvh _dyn with the gradient formed by the quotient of the load change and the valve lift change, a dynamic load change dt _{1, dyn is obtained} , to which the ignition and injection _parameters t _{1, tizw} for the steady-state engine state are added _later become. The addition of the stationary ignition and injection _parameters t _{l, tizw} with the value of the dynamic load change dt _{l, dyn} results dynami cal ignition and injection _parameters t _izw , which are to be _supplied to the responsible for the ignition and injection units of the internal combustion engine.

8th shows a flowchart with the individual steps, which are for predictive load control of an internal combustion engine, which has gas exchange valves with variable valve lift to perform. The 8th shown method steps are in the engine control and regulation MS 1 carried out.

According to a first method step 1 is determined from the accelerator pedal position, the engine speed and possibly other variables such as a vehicle dynamics control or manipulated variables of an electronic stability program, the current Vorgabelast t _{l, should} . The Vorgabelast t _{l, shall} in the following process step 2 in a function block TLDK, in which environmental conditions are considered, further processed. The ambient pressure p _a and the ambient temperature t _{a are} taken into account, a normalization to a standard pressure and a standard temperature being carried out. In the process step 2 may also provide results of an upstream load adaptation of a process step 3 be taken into account, wherein the load adaptation is performed in the function block TLA.

Following consideration of the environmental conditions, in a further process step 4 determines the target valve lift, which is carried out by the gas exchange valves according to the Vorgabelast. Valve switching is carried out in a TLVEN function block. This functional block can be a process step 5 be considered upstream, in which a bank equalization is taken into account, are compensated in the different state variables different cylinder banks of the internal combustion engine. The correction values for carrying out the bank equalization are determined in the function block BGS.

After determining the desired valve lift in the process step 4 in function block TLVEN takes place in the next process step 6 a query whether the required target pressure p _{s, should be} less than the ambient pressure p _a . In the no-branch, the throttle valve is brought into the open position (method step 8.2 ), in the Yes branch via the pressure control (process steps 8.1 and 9 ). The VLC controller is activated in each case (method step 7 ).

If the query in the process step 6 shows that the target pressure p _{s, should be} below the ambient pressure p _a , the Yes branch is corresponding to the method steps 8.1 and 9 continued, according to which a regulated throttle setting is made to produce a suction pipe negative pressure. In the process step 8.1 , which represents the function block TLVDK, the in 6 described regulation of the throttle position carried out in step 9 the control value is supplied to an actuator of the throttle valve for adjusting the throttle valve.

It may be appropriate, the Adjustment of the throttle valve in addition to the admission of Gas exchange valves perform. In In this case, there is no alternative throttle position setting. Rather, in any case, a throttle setting in addition to Charging the gas exchange valves performed, the size of the throttle setting over a map is determined. If the target pressure is close to the ambient pressure or exceeds the ambient pressure, the throttle position becomes the value of the associated map accordingly not or only minimally changed.

After determining the desired valve lift in the process step 4 is parallel to the setting of the gas exchange valves (method step 7 ) and / or the throttle valve (method steps 8.1 respectively. 8.2 and 9 ) according to the method steps 10 and 11 the ignition and the injection are performed, whereby the setting of the values for ignition and injection, the Vorgabelast is based. In the process step 10 First, an adaptation to dynamic processes in the internal combustion engine is performed in order to ensure that effects occurring in the instationary operation, in particular the inertias of mechanical control elements, are compensated. In the following process step 11 For example, the values based on the preliminary load, for adaptation to the dynamic processes in the internal combustion engine, for the ignition and the injection, are supplied to the associated engines of the internal combustion engine for the setting of the ignition time, the start of injection and the duration of injection.

Claims (16)

Method for operating an internal combustion engine, in which, as a function of acting on the internal combustion engine Vorgabelast (t _{l, soll} ) determines a target pressure (p _{s, soll} ) in the intake manifold of the internal combustion engine and adjusted via an air supply device for the supply of combustion air to the cylinders of the internal combustion engine is, wherein the ignition timing, the beginning of the injection and the duration of the injection according to a predetermined relationship depending on the Vorgabelast (t _{l, should} ) determined and supplied as a control signal actuators over which the ignition or the injection are set, characterized in that, during stationary operation of the internal combustion engine, a mean injection duration (t _{i, mw} ) is determined, from which an average load variable (t _{1, is} ) is determined, which is compared with the current feed load (t _{1, soll} ), the difference between Pre-load (t _{l, soll} ) and average load size (t _{l, is} ) in the determination v on ignition timing, start of injection and duration of injection is taken into account. A method according to claim 1, characterized in that from the Vorgabelast (t _{l, soll} ) a desired air volume (t _{l, mot} ) is determined, which is the setting of the air supply device used as a basis. A method according to claim 1 or 2, characterized in that the connection between ignition or injection and Vorgabelast is stored in a map. Method according to one of claims 1 to 3, characterized that the setting of the ignition or the injection is accompanied by a lambda control. Method according to one of claims 1 to 4, characterized that the setting of the ignition or the injection is underlined an engine knock control. Method according to one of Claims 1 to 5, characterized in that the external pressure (p _a ) and the outside temperature (T _a ) are taken into account in the determination of the ignition time, the start of the injection and the duration of the injection. A method according to claim 6, characterized in that the ignition timing, the beginning or the duration of the injection-determining control signal is proportional to the current external temperature (T _a ) and inversely proportional to the current external pressure (p _a ). Method according to one of claims 1 to 7, characterized in that the difference between Vorgabelast (t _{l, should} ) and average load size (t _{l, is} ) low-pass filtered and integrated. Method according to one of claims 1 to 8, characterized that at a load change dynamic effects of the air supply device are taken into account by dynamic transition area the actual Position of the air supply device determined and the settings for ignition and Injection of the actual Position of the air supply device are carried out accordingly. Method according to one of claims 1 to 9, characterized that used as an air supply gas exchange valves with variable valve timing become. A method according to claim 10, characterized in that the desired valve lift (H _{V, soll} ) of the gas exchange valves in dependence of the engine speed (n _is ) is determined. A method according to claim 10 or 11, characterized in that the desired valve lift (H _{V, soll} ) of the gas exchange valves in dependence of the desired air volume (t _{l, mot} ) is determined. A method according to any one of claims 10 to 12, characterized in that a throttle device is as an air supply device in addition to the variable controllable gas exchange valves provided in the intake pipe, which is used in operating points of the internal combustion engine, in which the target pressure to be set _(to p) below ambient pressure (p _A ) is located. A method according to claim 13, characterized in that the adjustment of the throttle body of the throttle device as a function of the desired valve lift (H _{V, should} ) of the gas exchange valves takes place. Method according to one of claims 1 to 14, characterized that the internal combustion engine at least two separately adjustable cylinder banks has and at least one the behavior of the internal combustion engine descriptive engine characteristic (ignition timing, Start of injection, duration of injection, opening and closing curves the gas exchange valves) for each cylinder bank is determined, taking in case of a difference between the characteristics of the cylinder banks at least one cylinder bank is manipulated in such a way that the average value of the considered characteristics of all cylinder banks Target average equivalent. Method according to claim 15, characterized in that that determines the actual injection times in each cylinder bank become.