EP1776519A1

EP1776519A1 - Method and device for controlling and diagnosing a camshaft displacement device

Info

Publication number: EP1776519A1
Application number: EP05773839A
Authority: EP
Inventors: Martin Jehle; Gerhard Schopp; Hong Zhang
Original assignee: Siemens AG
Current assignee: Continental Automotive GmbH
Priority date: 2004-08-12
Filing date: 2005-08-01
Publication date: 2007-04-25
Also published as: CN101040110A; DE102004039216A1; WO2006018377A1; KR20070046888A; CN100549394C; KR101196129B1; DE102004039216B4

Abstract

The invention relates to an internal combustion engine comprising a camshaft that acts on gas exchange valves, and a phase displacement device by which means a phase (PH) between the camshaft and a crankshaft can be displaced. Said internal combustion engine also comprises an exhaust gas probe which is used to detect a variable characterising an air/fuel ratio in the cylinder, at least one sensor for detecting the phase (PH), and at least one regulating element which acts on the internal combustion engine. Measuring data records (MDS) associated with the different detected phases (PH) are determined, and comprise, in addition to the detected phase (PH), at least the detected variable characterising the air/fuel ratio in the cylinder. An optimisation method (OPT) is carried out, enabling a correction value to be determined for the detected phase (PH) according to the measuring data records (MDS), such that a quality function (GF) that depends on the variables associated with the measuring data records (MDS) is minimised or maximised. During the subsequent operation of the internal combustion engine, at least one regulating variable for controlling a regulating element is determined according to a detected phase (PH) corrected by means of at least one correction value (dPH). A defect in the internal combustion engine is diagnosed according to the correction value (dPH) for the detected phase (PH).

Description

description

METHOD AND DEVICE FOR CONTROLLING AND DIAGNOSIS OF A CAMSHAFT ADJUSTING DEVICE

The invention relates to a method and a device for controlling or diagnosing an internal combustion engine.

On internal combustion engines increasingly high demands are placed on their performance and efficiency. At the same time, due to strict legal regulations, pollutant emissions must also be low. For this purpose, it is known to provide internal combustion engines with a plurality of actuators for adjusting a charge in the respective combustion chambers of the cylinders of the internal combustion engine, wherein the charge prior to combustion consists of a mixture of air, fuel and possibly also exhaust gases. For example, phase adjusting devices are known, by means of which a phase between a crankshaft and a camshaft of the internal combustion engine can be changed and thus the respective beginning and the respective end of the opening or closing of the gas inlet and Gasauslassven¬ tile can be changed. In addition, valve lift adjusting devices are also known, by means of which a valve stroke of the gas inlet valve or else of a gas outlet valve of the internal combustion engine can be adjusted between a low and a high valve lift.

In addition to such actuators, a precise control of the internal combustion engine is necessary in particular for low-emission operation of the internal combustion engine. The object of the invention is to provide a method and a device for controlling an internal combustion engine or for diagnosing the internal combustion engine, which is precise.

The object is solved by the features of the independent claims. Advantageous embodiments of the invention are characterized in the subclaims.

The invention is characterized by a method and a corresponding device for controlling or diagnosing an internal combustion engine with a camshaft, which acts on gas exchange valves, with a phase adjustment device, which means a phase between the camshaft and a crankshaft is adjustable, with an exhaust gas probe, by means of which an air / fuel ratio in a cylinder charak¬ terisierende size is detected, with at least one sensor for detecting the phase and with at least one actuator, which acts on the internal combustion engine. The phase between the camshaft and the crankshaft is understood to mean a phase angle between the crankshaft and the camshaft relative to respective reference positions of the crankshaft and the camshaft.

According to the invention, measurement data sets are determined which are assigned to different detected phases and which, in addition to the detected phase, comprise at least the detected variable characterizing the air / fuel ratio in the cylinder. An optimization method is carried out, by means of which a correction value for the detected phase is determined as a function of the measurement data records in such a way that a performance function is minimized or maximized, which depends on the quantities assigned to the measurement data records. The measured data sets can include variables, but the measured variables are also from these derived variables or manipulated variables of the internal combustion engine.

In the further operation of the internal combustion engine, at least one manipulated variable for controlling an actuator of the internal combustion engine is determined as a function of a detected phase corrected by means of the correction value. By means of the correction value determined in this way, inaccuracies in the acquisition of the phase and / or in the further determination of the manipulated variable can be corrected simply and precisely. Of course, the detected phase may also be expressed as an inlet-closing angle of a gas inlet valve at which the gas inlet valve is in its closed position. Of course, the detected phase may also be expressed as an inlet opening angle of the gas inlet valve, at which the gas inlet valve leaves its closed position and releases the inlet of the respective cylinder of the internal combustion engine. In addition, the detected phase may also be expressed as an outlet-closing angle of a gas outlet valve in which the gas outlet valve is in its closed position. Further, the detected phase may also be expressed as an outlet opening angle of the gas outlet valve, at which the gas outlet valve leaves its closed position and releases an outlet of the cylinder.

An error of the internal combustion engine is diagnosed as a function of the correction value for the detected phase. Thus, for example, an error of the internal combustion engine is detected depending on whether the correction value for the detected phase exceeds an upper threshold value or falls below an lower threshold value. It can be so very accurate an error of the internal combustion engine, especially in the field the phase adjusting device and the camshaft, are detected.

In an advantageous embodiment of the invention, the correction value for the detected phase is an additive correction value. This is based on the knowledge that faults in practice can be compensated for particularly well by such an additive correction value.

In a further advantageous embodiment of the invention, a correction value for a fuel mass to be metered is determined by means of the optimization method. This has the advantage that it can be easily avoided that errors of influencing variables for the fuel mass to be metered affect the correction value of the phase.

According to a further advantageous embodiment of the invention, the correction value for the fuel mass to be metered is a multiplicative correction value. This is based on the knowledge that such an error, caused by influencing variables of the fuel mass to be metered, can be compensated particularly well, that is to say errors attributable to tolerances of the injection valve or the fuel feed or the like.

According to a further advantageous embodiment of the invention, the quality function depends on a desired value of the variable, which characterizes the air / fuel ratio in the cylinder, and a control value of a lambda controller or a lambda adaptation. This has the advantage that the correction value for the phase can be determined particularly simply and precisely. According to a further advantageous embodiment of the invention, in the presence of a first and a second camshaft, which are associated with the gas inlet valves or gas outlet valves, and corresponding first and second phase adjusting devices and first and second sensors for detecting the respective first and second second phase, first the measured data records of the detected phase recorded while maintaining the second phase and then a correction value for the first phase is determined by means of the optimization process. Subsequently, the measured data sets of the detected second phase are first detected while maintaining the first phase and then a correction value for the second phase is determined by means of the optimization method.

In this way it can be ensured that errors are taken into account when detecting the corresponding phase by the respective correction value of the corresponding phase and, if appropriate, the errors attributable to the respective other phase are not taken into account. This advantage is also achieved when the order of determining the first phase correction value and the second phase correction value is reversed.

According to a further advantageous embodiment of the Erfin tion the measured data sets are determined while maintaining the current valve lift in the presence of a valve lift adjustment of the gas exchange valves. In this way, the correction value can be determined so precisely. There is then no error influence by adjusting the valve lift and the results are very well reproducible. In this context, it is particularly advantageous if own correction values are determined for each setting of the valve lift. Thus, tolerances in the arrangement verschie¬ dener cams which are each associated with a gas exchange valve, better taken into account.

In this context, it is also advantageous if the measured data records are determined at the lowest valve lift of the gas exchange valves. For example, it is possible to dispense with the determination of a further correction value in the event of a higher valve lift of the gas exchange valves, and a very precise determination of the correction value of the phase can take place, since phases affected by the lowest valve lift have a stronger effect and therefore the error has an effect higher quality can be compensated by the optimization method.

Embodiments of the invention are explained below with reference to the schematic drawings. Show it:

1 shows an internal combustion engine with a control device,

FIG. 2 shows a further view of first parts of the internal combustion engine according to FIG. 1,

FIG. 3 shows a further view of further parts of the internal combustion engine according to FIG. 1,

FIG. 4 shows a flow diagram of a first program for determining correction values;

Figure 5 is a flowchart of a program for controlling the internal combustion engine and FIG. 6 is a flow chart of a second program for determining correction values.

FIG. 7 is a flow chart of a third program for determining correction values.

FIG. 8 is a flow chart of a fourth program for determining correction values.

Elements of the same construction or function are gekennzeich¬ net figures across the same reference number gekennzeich¬ net.

An internal combustion engine (FIG. 1) comprises an intake tract 1, an engine block 2, a cylinder head 3 and an exhaust tract 4. The intake tract 1 preferably comprises a throttle valve 5, furthermore a collector 6 and an intake manifold 7, which lead to a cylinder Zl is guided via an inlet channel in the Motor¬ block 2. The engine block 2 further includes a crankshaft 8, which is coupled via a connecting rod 10 with the Kol¬ ben 11 of the cylinder Zl.

The cylinder head 3 comprises a valve drive with a gas inlet valve 12, a gas outlet valve 13 and Ventilantrie¬ be 14, 15th

A camshaft 18 is provided which includes cams 16, 17a, 17b acting on the gas inlet valve 12. Furthermore, a valve lift adjusting device 19 (FIG. 3) is provided, which is designed in such a way that either the cam 16 with a low valve lift VL acts on a plunger of the gas inlet valve 12 or in another Switching position of the valve lift adjustment 19 the No¬ bridges 17a, 17b with a high valve lift VL act on the plunger of the gas inlet valve 12.

The valve lift adjustment device 19 can, for example, form part of a tappet associated with the gas inlet valve 12. However, it can also be designed as a further element connected mechanically between the cams 16, 17a, 17b. It can also be designed such that it, for example, axially displaces the camshaft 18 and in this way can be switched from a higher to a lower valve lift or vice versa.

Furthermore, a phase adjusting device 20 (FIG. 2) is provided, by means of which a phase between the crankshaft 8 and the camshaft 18 can be adjusted. This adjustment of the phase can be carried out, for example, by increasing a hydraulic pressure in high-pressure chambers of the phase adjusting device 20 or decreasing the corresponding pressure, depending on the direction in which the adjustment of the phase is to take place. A possible adjustment range of the phase is indicated by an arrow 21.

Preferably, at least two camshafts 18, 18 ^Λ hen vorgese¬, a first camshaft 18 Gasein¬ the respective outlet valves 12 and a second camshaft 18 ^Λ the jeweili¬ gen gas outlet valves 13 is associated. In particular, the second camshaft 18 ^Λ can be mechanically coupled in a simple Ausführungs¬ form with a fixed phase to the crankshaft 8 with this. However, it can also be coupled to the crank shaft 8 via a corresponding phase adjustment device. In this case, then the phase of the second camshaft 18 ^{Λ can be} changed. By varying the phase PH between the crankshaft 8 and the camshaft 18, the valve overlap of the gas inlet valve and the gas outlet valve 13 can be varied, that is, the crankshaft angle range during which an inlet and an outlet of the cylinder Z1 are released becomes. The phase adjustment device 20 and also the valve lift adjustment device 19 can also be designed in any other manner known to the person skilled in the art.

The cylinder head 3 further comprises an injection valve 22 and a spark plug 23. Alternatively, the injection valve 22 may also be arranged in the intake manifold 7.

A control device 25 is provided, which is assigned to sensors which detect different measured variables and in each case determine the value of the measured variable. The control device 25 determines dependent on at least one of the measured variables Stell¬ sizes, which are then converted into one or more control signals for controlling the actuators by means of appropriate actuators. The control device 25 can also be referred to as a device for controlling the internal combustion engine.

The sensors are a pedal position sensor 26, which detects an accelerator pedal position of an accelerator pedal 27, a Luftmas¬ sensensor 28, which detects an air mass flow upstream of the throttle valve 5, a throttle position sensor 30 which detects an opening degree of a throttle, a first temperature sensor 32, which Ansauglufttempe¬ an intake manifold pressure sensor 34, which detects an intake manifold pressure P_IM in the accumulator 6, detects a crankshaft angle sensor 36 which detects a crankshaft angle, then a speed N is assigned. A second temperature sensor 38 detects a coolant temperature. Further, a camshaft angle sensor 39 is provided, which detects a camshaft angle. If two camshafts are present, each camshaft is preferably associated with a camshaft angle sensor 39, 40. Furthermore, an exhaust gas probe 42 is provided, which detects a residual oxygen content of the exhaust gas and whose measurement signal is characteristic of the air / fuel ratio in the cylinder Z1. A separate sensor for detecting the phase PH can also be provided. Preferably, however, the at least one sensor for detecting the phase is formed by the camshaft angle sensor 39, 40 and the crankshaft angle sensor 36.

Depending on the embodiment of the invention, any desired quantity of said sensors may be present, or additional sensors may also be present.

The actuators are, for example, the throttle valve 5, the gas inlet and gas outlet valves 12, 13, the valve lift adjustment device 19, the phase adjustment device 20, the injection valve 22 or the spark plug 23.

In addition to the cylinder Zl, further cylinders Z2 to Z4 are preferably also provided, to which corresponding actuators are then assigned.

A program for determining a correction value is stored in a program memory of the control device 25 and can be executed during the operation of the internal combustion engine. The program is started in a step S1 (FIG. 4). This can be done, for example, at predetermined time intervals, for example at each engine start. Alternatively, you can the program can also be started if a predetermined distance has been traveled since the start or if predetermined operating conditions are present which are favorable for the execution of the program. If necessary, variables are also initialized in step S1.

In a step S2, measurement data sets MDS are acquired. Each measured data set MDS are current values at the time of the acquisition of the measured data set MDS of an actual value LAM_AV of the air / fuel ratio, a desired value LAM_SP of the air / fuel ratio, a control value FAC_LAM ei¬ nes lambda controller, a phase PH between the crankshaft. 8 and the camshaft 18, the rotational speed N and the intake manifold pressure P_IM assigned. In addition, additional values of measured variables or variables derived therefrom or other manipulated variables of the internal combustion engine can also be assigned to the respective measured data record MDS.

The control device 25 also includes a lambda control, which is preferably stored in the form of a program in the program memory of the control device and is executed during the operation of the internal combustion engine. In addition, a so-called lambda adaptation is preferably also provided. The control difference of the lambda controller is the difference of the setpoint LAM_SP and the actual value LAM_AV of the air / fuel ratio. The controller itself is usually designed as a PIl2D controller. The controller also includes a lambda adaptation, into which a predefinable part of the control value FAC_LAM of the lambda controller is adopted under predetermined adaptation conditions. In the following, the manipulated variable FAC_LAM is understood to mean both the output of the lambda controller and the lambda adaptation. The manipulated variable FAC_LAM is preferably multiplicative in determining a mit- Fuel injector 22 to be metered into the combustion chamber of the cylinder Zl to Z4 fuel mass.

The phase PH is the angle between the crankshaft 8 and the camshaft 18 or possibly the camshaft 18 'with respect to the respective reference positions of the crankshaft 8 and the camshaft 18, 18'. The measured data sets MDS are preferably detected with as many different phases PH as possible, the measured data sets preferably include phases PH which essentially correspond to the entire adjustment range of the phase adjusting device 20. The measured data sets MDS are temporarily stored in a buffer of the control device 25 in step S2.

In a step S4, a correction value dPH of the phase PH and a correction value dMFF for the fuel mass to be metered are determined by means of an optimization method OPT. The optimization method OPT is designed such that it minimizes or maximizes a quality function GF, which depends on the measurement data sets and the correction values dPH, dMFF of the phase PH and the fuel mass to be metered. The quality function GF can be derived as exemplified below.

An air mass flow MAF in the respective cylinders Z1 to Z4 is given by the following equation F1:

MAF = η_l (N, ES = f (PH)) * P_IM - η_2 (N, VO = f (PH)) - η_3 (N, AS = f (PH)) (Fl)

ES denotes an inlet-closing angle, ie the crankshaft angle at which the gas inlet valve 12 just reaches its closing position after an opening process, in which it again closes the inlet of the cylinder Z1 to Z4. Particularly easy, the inlet-closing angle ES can be determined depending on the phase PH between the crankshaft 8 and the camshaft 18.

VO denotes a valve overlap, i. the crank angle range during which both the gas inlet valve 12 and the gas outlet valve 13 release the inlet or the outlet of the cylinder Z1 to Z4. The valve overlap VO can also be determined simply from the phase PH between the crankshaft 8 and the camshaft 18, provided that the camshaft 18 'is not associated with a phasing adjustment device and thus in a fixed phase relationship the crankshaft 8 is mechanically coupled. If the camshaft 18 'is also associated with a phasing adjustment device, then the phase between the crankshaft 8 and the camshaft 18' is referred to as second phase PH_A, while then the phase between the crankshaft 8 and the camshaft 18 as the first phase PH_E be¬ draws. In this case, the valve overlap VO is determined as a function of the first and second phases PH_E, PH_A. The respective phase PH, PH_E, PH_A can be carried out simply by evaluating the measuring signals of the crankshaft angle sensor 36 and the respective camshaft angle sensor 39, 40.

AS designates an outlet-closing angle, ie the crankshaft angle at which the gas outlet valve 13 has moved back into its closed position after a release of the outlet of the cylinder Z1. The outlet-closing angle can also be determined as a function of the phase PH of those camshaft 18, 18 'whose cams act on the gas outlet valve 13. η_l is a first swallowing contribution, which is determined as a function of the rotational speed N and the inlet-closing angle ES from a characteristic map, preferably by means of characteristic map interpolation. The map is stored in a data memory of the control device 25.

η_2 is a second swallow contribution, which is preferably determined from a further characteristic field as a function of the rotational speed N and the valve overlap VO, preferably by means of map interpolation. The further characteristic map is also stored in the data memory of the control device 25.

η_3 is a third swallow contribution, which is also determined from still another map depending on the speed N and the outlet-closing angle, preferably by means of Kennfeldinterpola¬ tion. The still further map is stored in the data memory of the control device. By means of the relationship F1, the so-called absorption behavior of the internal combustion engine is modeled with respect to the air mass flow MAF flowing into the cylinder. In this case, the first two terms of the relationship F1 generally have the decisive influence on the swallowing behavior.

Further, the following relationship (F2) is set:

LAM_AV = LAM_SP * (MAF (PH + dPH) / MAF (PH)) / (dMFF * FAC_LAM) (F2)

The relationship F2 comprises forming a ratio of the air mass flow MAF flowing into the cylinder taking into account the correction value dPH of the phase and determining the correction value dPH of the phase without consideration. The relationship F2 preferably forms the basis for forming the quality function GF, which is, for example, a quadratic error of the relationship F2 for all acquired measurement data sets MDS. The quality function GF is shown below by way of example with reference to the relationship F3.

GF = ^ (LAM-AV ₁ - LAM-SP ₁ *

(MAF (PHi + dPH) / MAF (PH ₁ )) / (dMFF * FAC-LAM ₁ )) ² (F3)

i denotes the respective measured data record MDS, that is to say its position in a list of the measured data records MDS. The goods function GF is preferably minimized by means of a numerical optimization method OPT, and thus the optimum values are determined with regard to the acquired measurement data sets MDS of the correction values dPH of the phase PH and of the correction value dMFF for the fuel mass to be metered. The correction values dPH, dMFF of the phase or of the fuel mass to be metered form a parameter vector b.

(dPH λb = (F4)

{DMFF)

Preferably, an iterative gradient method is used as the optimization method OPT. The iteration of the parameter vector b can be carried out, for example, according to the following rule.

b _{n + 1} = b _n * -α GRAD (GF) | b _n (F5)

The index n designates the current iteration step, while n + 1 designates the next iteration step. GRAD denotes a gradient of the quality function GF. α denotes a scalar step size. The starting values for the iterative optimization method with respect to the parameter vector b are preferably the correction values dPH, dMFF of the phase PH or of the fuel mass to be metered determined during the last run of the optimization method. Alternatively, fixed values can be used. According to the formula F5, the negative gradient GRAD of the quality function GF is used as the search direction, which is also referred to as the descent direction. This has the advantage that each of the steepest descent is the search direction.

The scalar step size α is preferably determined by minimizing in the gradient direction. The execution of the optimization method OPT is aborted if a minimum number of iterations has been exceeded or if the changes from one iteration to the next with regard to the parameter vector b are below a predetermined threshold.

A particularly good convergence of the optimization method OPT arises when the so-called Lebenberg method is used as the gradient method. However, it is also possible to use any other optimization methods OPT which are suitable for this purpose.

With regard to the gradient method, there is a corresponding disclosure in the textbook "Optimization: Static, Dynamic, Stochastic Methods for the Application, Markus Papageorgiou, Munich, Vienna: Oldenburg, 1991, ISBN 3-486-21799-2, page 35 to page 51 , the contents of which are hereby incorporated. The above textbook also discloses further optimization methods OPT. Subsequent to step S6, the program is ended in step S6.

A program for controlling the internal combustion engine is explained in more detail below with reference to the flowchart of FIG. The program is started in a step S8 in which variables are initialized if necessary. The start preferably follows shortly after an engine start or directly at the engine start of the internal combustion engine. In a step S10, the air mass flow MAF flowing in the combustion chamber of the respective cylinder Z1 to Z4 is determined as a function of the current intake pipe pressure P_IM and the phase PH which is corrected additively by means of the correction value dPH of the phase PH. The determination of the air mass flow MAF to be set into the respective combustion chamber of the cylinder Z1-Z4 in the step S10 is preferably carried out with corresponding application of the relationship F1, the air mass flow MAF being dependent on the corrected phase, ie also dependent on the correction value dPH Phase PH is determined.

In a step S12, a control signal SG_INJ for metering fuel by means of the injection valve 22 is subsequently determined as a function of the air mass flow MAF. Alternatively, or in addition, in step S12, further control signals for further actuators of the internal combustion engine can be determined.

In a subsequent step S14, the program remains for a predetermined waiting time T_W before the processing is continued again in the step S10. While the program remains in step S14, other programs can be executed in the control device 25. Alternatively or additionally, a diagnosis of the camshaft adjustment can also be performed by the program according to FIG. In this case, it is checked whether the correction value dPH of the phase PH falls below or exceeds predefined threshold values. If this is the case, an error of the camshaft adjustment is detected. In this case, appropriate diagnostic measures, such as emergency operation or signaling to a vehicle driver of a vehicle in which the internal combustion engine is arranged, are then initiated. The signaling or even the diagnostic measures can only take place when the threshold values have been repeatedly exceeded or fallen below by several times during repeated execution of the program for determining the correction value dPH of the phase PH.

A second embodiment of the program for determining the correction values is started in a step S16 (FIG. 6) in which variables are initialized if necessary. In a step S18, measurement data sets MDS are essentially determined in accordance with step S2. The program of FIG. 6 is particularly suitable when the internal combustion engine has a valve lift adjustment device 19, by means of which the valve lift VL of the gas exchange valves 13 can be adjusted between a small valve lift VL_L and a high valve lift VL_H. Preferably, the measurement data records MDS are detected in the step S18 at the low valve lift VL_L. The measurement data sets MDS, which are detected in step Sl8, preferably also include the valve lift VL.

In a step S20, the correction value dPH of the phase PH and the correction value dMFF of the fuel quantity to be metered are subsequently determined by means of the optimization method OPT. in consideration of the measured data sets MDS and the valve lift VL detected in step S18, which is preferably the smaller valve lift VL_L. The procedure with regard to the optimization method OPT here corresponds essentially to that of step S4. In contrast to the step S4, in the equation F1, the valve lift VL is taken into account in at least one of the swallowing values η_l, η_2, η_3. The program is then ended in a step S22.

A third embodiment of the program for determining the correction values is started in a step S24 (FIG. 7) in which variables are initialized if necessary.

In a step S26, first measured data sets MDS1 are acquired, specifically in accordance with the procedure of step S18. The acquisition of the first measurement data sets MDS1 is preferably carried out while maintaining the small valve lift VL_L.

In a step S28, which corresponds to step S20, a correction value dPH_VL_L of the phase at low valve lift VL_L and the correction value dMFF of the fuel quantity to be metered are determined by means of the optimization method OPT.

Subsequently, in a step S30, second measured data sets MDS2 are detected and temporarily stored in the intermediate memory of the control device 25. During the detection of the second measurement data sets MDS2, the valve lift of the gas inlet valves 12 is preferably set to the high valve lift VL_H.

In a step S32, a correction value dPH_VL_H of the phase PH at a high valve lift VL_H and the correction value dMFF of the fuel mass to be metered are then applied using the Optimization method OPT and on the basis of the zwei¬ th measured data records MDS2 and taking into account that the valve lift VL was a high valve lift VL_H when detecting the zweit¬ th measured data records MDS2 determined.

A particularly rapid determination of the correction value dPH_VL_H of the phase PH at a high valve lift VL_H in step S32 can be achieved by assigning the value determined in step S28 to the correction value dMFF of the fuel mass to be metered as the starting value of the iterative optimization method.

Subsequently, the process is ended in a step S34.

The determination of the air mass flow MAF in step S10 then takes place with appropriate consideration of the correction value dPH_VL_L of the phase PH at low valve lift VL_L, when a small valve lift VL_L is currently set and taking into account the correction value dPH_VL_H of the phase PH at high valve lift VL_H if a high valve lift VL_H is currently set.

A fourth embodiment of the program for determining the correction values is started in a step S36 (FIG. 8) in which, if necessary, variables are initialized.

This program is particularly suitable for internal combustion engines, each of which is assigned a camshaft for the gas inlet valves 12 and for the gas outlet valves 13 and these camshafts 18, 18 'are each associated with phase adjustment devices 20. In a step S38, third measured data records MDS3 are acquired. This essentially takes place in accordance with the procedure of step S2, with the difference that the measurement data records current values of the phase PH_E the first No¬ ckenwelle, ie the camshaft, which is associated with the gas inlet valves 12, and values of the phase PH_A the second No¬ camshaft 18 ', ie the camshaft which is associated with the Gasauslassventi¬ len 13 include. The acquisition of the third measurement data records MDS3 takes place while maintaining the phase PH_A of the second camshaft 18 '.

In a step S40, a correction value dPH_E of the phase PH of the first camshaft and the correction value dMFF of the fuel mass to be metered are then carried out by performing the optimization method OPT taking into account the third measurement data sets MDS3 and the phase PH_A of the second camshaft set during the detection of the third measurement data sets determined. The optimization process is carried out in accordance with the procedure of step S4.

In a subsequent step S42, fourth measured data sets MDS4 are detected, in which case the phase PH_E of the first camshaft is kept substantially constant and thus only the phase PH_A of the second camshaft is varied. The procedure of step S42 is thus analogous to that of step S38.

In a step S44, a correction value dPH_A of the phase of the second camshaft 18 'and the correction value dMFF of the fuel quantity to be metered are subsequently determined by carrying out the optimization method OPT, taking into account the fourth measurement data sets MDS4 and the phase PH_E of the first camshaft when detecting the fourth measurement records MDS4. This is analogous to the procedure of step S40.

A particularly precise determination of the correction value dPH_A of the phase of the second camshaft 18 'takes place when the correction value dPH_E of the phase of the first camshaft 18 determined in the step S40 is taken into account in the quality function GF. A particularly fast convergence of the optimization process results when the one used as the starting value for the correction value dMFF of the fuel mass to be metered is used, which was determined in step S40.

Subsequently, the process is ended in a step S46.

By means of the correction value of the phase, even in an internal combustion engine having a plurality of cylinder banks, for example in a V-engine, differences in the camshaft positions of the camshafts assigned to the respective cylinder banks can take place and thus improved synchronization of the internal combustion engine can be achieved.

The optimization method OPT can also be based on the approach described below.

An imputed air mass flow MAF_CALC is determined according to the following relationship.

MAF_CALC = (LAM_AV / LAM_SP) * MAF * FAC_LAM (F6)

By means of the optimization method OPT, a first device equation (F7) is approximated by using the measurement data sets MDS. MAF = G1 * PH + OFFS1 (F7)

Gl denotes a first slope and OFFS1 a first gradient section.

This is preferably done while minimizing the quadratic error, as disclosed in the textbook "Signal Processing: Numerical Processing of Digital Signals", E. Schrüfer, Munich, Vienna, Hanser 1990, ISBN 3-446-15944-4, pages 74-76 ¬ beard, the content of which is hereby incorporated in this regard.

By means of the optimization method OPT, a second straight line equation (F8) is further approximated by using the measured data sets MDS.

MAF_CALC = G2 * PH + OFFS2 (F8)

G2 denotes a second slope and OFFS2 a second straight line section.

This is preferably also done while minimizing the quadratic error.

The correction value dMFF for the fuel mass to be metered is then determined according to the following relationship.

dMFF = G1 / G2 (F9)

The correction value dPH for the phase PH is then determined according to the following relationship.

dPH = (OFFS2 / G2) - (OFFS1 / G1) (F9)

Claims

claims

1. A method for controlling an internal combustion engine with a camshaft (18, 18 ') which acts on gas exchange valves, with a phase adjusting device (20), by means of a phase (PH) between the camshaft (18, 18') and a Kur ¬ belwelle (8) is adjustable, with an exhaust gas probe (42), mit¬ means of an air / fuel ratio in a Zylin¬ (Zl to Z4) characterizing size is detected, with at least one sensor for detecting the phase ( PH) and with at least one actuator, which acts on the internal combustion engine, in which

- Measurement data sets (MDS) are determined, which are assigned to different detected phases (PH) and in addition to the detected phase (PH) at least the detected, the air / fuel ratio in the cylinder (Zl to Z4) characterizes include size,

- An optimization method (OPT) is performed, by means of which a correction value (dPH) for the detected phase (PH) depending on the measurement data sets (MDS) is determined in such a way that a quality function (GF) is minimized or maximized depends on the measured data sets (MDS) zu¬ ordered sizes, and

- In the further operation of the internal combustion engine at least one manipulated variable for controlling an actuator depending on the means of the correction value (dPH) corrected, detected phase is determined.

2. A method for diagnosing an internal combustion engine with a camshaft (18, 18 '), which acts on gas exchange valves, with a phase adjusting device (20), by means of a phase (PH) between the camshaft (18, 18') and a Kur ¬ belwelle (8) is adjustable, with an exhaust gas probe (42), mit- in which a variable characterizing an air / fuel ratio in a cylinder (Z1 to Z4) is detected, with at least one sensor for detecting the phase (PH) and with at least one actuator acting on the internal combustion engine, in which

- An error of the internal combustion engine is diagnosed dependent on the correction value (dPH) for the detected phase

(PH).

A method according to any one of the preceding claims, wherein the detected phase correction value (dPH) is an additive correction value.

4. The method according to any one of the preceding claims, wherein by means of the optimization method (OPT) a Korrek¬ turwert (dMFF) for a metered fuel mass is ermit¬ telt.

5. The method of claim 4, wherein the correction value (dMFF) for the fuel mass to be metered is a multiplicative correction value.

6. The method according to any one of the preceding claims, wherein the quality function (GF) depends on a target value of the size, which characterizes the air / fuel ratio in the cylinder (Zl to Z4), and a control value (LAM_FAC) of a lambda controller or a lambda adaptation.

7. The method according to any one of the preceding claims, wherein in the presence of a first and a second camshaft (18, 18 '), which is associated with the gas inlet valves (12) and the gas outlet valves (13), and corresponding first and second phases -Verstelleinrichtungen and first and second sensors for detecting the respective first and second phase (PH_E, PH_A), first the measurement data sets (MDS_3) of the detected first phase (PH_E) are detected while maintaining the second phase (PH_A) and then by means of Optimization method (OPT) a correction value (dPH_E) for the first phase (PH_E) is determined, then first the measured data sets (MDS_4) of the detected zwei¬ th phase (PH_A) are detected while maintaining the first phase (PH_E) and then by means of of the optimization process (OPT), a correction value (dPH_A) for the second phase is determined.

8. The method according to any one of the preceding claims, wherein in the presence of a first and a second camshaft (18, 18 ') which is associated with the gas inlet valves (12) and the gas outlet valves (13), and corresponding first and second phases -Verstelleinrichtungen and first and second sensors for detecting the respective first and second phase (PH_E, PH_A), first the measurement data sets (MDS_4) of the detected second phase (PH_A) are detected while maintaining the first phase (PH_E) and then by means of Optimization method (OPT) a correction value (dPH_A) is determined for the second phase (PH_A), then first the measured data sets (MDS_3) of the detected first phase (PH_E) are detected while maintaining the second phase (PH_A) and then by means of the optimization process (OPT) Correction value (dPH_E) for the first phase (PH_E) is determined.

9. The method according to any one of the preceding claims, wherein in the presence of a valve lift adjusting device (19) of the gas exchange valves, the measured data sets (MDS) while maintaining the current valve lift (VL) can be determined.

10.A method according to claim 9, wherein for each setting of the valve lift (VL) own correction values (dPH_VL_L, dPH_VL_H) of the phase (PH) are determined.

11.Verfahren according to claim 8, wherein the measuring data sets (MDS) are determined only at the lowest valve lift (VL_L) of Gaswech¬ selventile.

12. An apparatus for controlling an internal combustion engine with ei¬ ner camshaft (18, 18 '), which acts on gas exchange valves ein¬, with a phase-adjusting device (20) by means of a phase (PH) between the camshaft (18, 18' ) and a crankshaft (8) is adjustable with an exhaust gas probe (42) by means of which an air / fuel ratio in a Zy¬ cylinder (Zl to Z4) characterizing size is detected, with at least one sensor for detecting the phase ( PH) and with at least one actuator, which acts on the internal combustion engine, wherein the device is designed for - determining measurement data sets (MDS), which are assigned to different er¬ Fassten phases (PH) and in addition to the detected phase (PH) comprise at least the detected, the air / fuel ratio in the cylinder (Zl to Z4) characterizing size,

- Performing an optimization method (OPT), by means of which a correction value (dPH) for the detected phase (PH) depending on the measurement data sets (MDS) is determined in such a way that a quality function (GF) is minimized or maximized, which depends from the measured data sets (MDS) zu¬ ordered sizes, and

- Determining at least one manipulated variable for controlling an actuator depending on the corrected by means of the correction value (dPH), detected phase in the further operation of the internal combustion engine.

13. A device for diagnosing an internal combustion engine with ei¬ ner camshaft (18, 18 '), which acts on gas exchange valves ein¬, with a phase-adjusting device (20) by means of a phase (PH) between the camshaft (18, 18' ) and a crankshaft (8) is adjustable with an exhaust gas probe (42) by means of which an air / fuel ratio in a Zy¬ cylinder (Zl to Z4) characterizing size is detected, with at least one sensor for detecting the phase ( PH) and with at least one actuator, which acts on the internal combustion engine, wherein the device is designed for

- Determining measurement data sets (MDS), which are assigned to different er¬ fassten phases (PH) and in addition to the erfass¬ th phase (PH) at least the detected, the air / fuel ratio in the cylinder (Zl to Z4) characterizing size include,

Performing an optimization method (OPT) by means of which a correction value (dPH) for the detected phase (PH) is determined as a function of the measurement data records (MDS) in such a way that a quality function (GF) is minimized or maximized. is dependent on the measured data sets (MDS) zu¬ ordered sizes, and

Diagnosing a fault of the internal combustion engine depending on the correction value (dPH) for the detected phase (PH).