DE60302426T2 - Method and device for monitoring the position of a variable valve control - Google Patents

Description

TECHNICAL TERRITORY

The The invention relates to a method for monitoring the position of a variable valve control in an internal combustion engine according to the preamble of claim 1. In particular, the invention relates to a method to monitor, which of a first cam with a first cam profile and a second cam having a second cam profile which is greater than the first cam profile is currently on lift mechanisms for gas exchange valves acting to control a gas exchange in or out of the Variety of cylinders are arranged. The invention also relates a device for monitoring the position of a variable valve timing in an internal combustion engine according to the preamble of claim 10. In particular, the Invention an apparatus for monitoring, which of a first cam with a first cam profile and a second cam having a second cam profile which is greater than the first cam profile is currently on lift mechanisms for gas exchange valves acting to control a gas exchange in or out of the Variety of cylinders are arranged.

BACKGROUND THE INVENTION

combustion engines for use in vehicles, for example, have to operate with different Engine speeds and loads capable be. The timing of opening and closing The intake and exhaust valves must be adjusted to the net power and efficiency of the engine over to optimize a reasonable range of speeds and loads.

at a four-stroke engine with a high performance, a multiple valve and a spark ignition, which For example, it is designed to work at high engine speeds generally desired Provide device such as cams to open the To control intake valves, which preferably has a long valve opening period to maximize the combustible charge which while the intake strokes of the engine is drawn into the combustion chambers.

This has the advantage of improving the degree of delivery of the engine and increased thereby the maximum achievement and torque outputs of the engine.

If such a motor is operated at speeds which are below the lying at which the maximum power can be developed because the intake valves for a relatively long period of time open are, during the intake stroke of the same something of the combustible filling, which is drawn into each combustion chamber, pushed back through the valve, before it closes. This effect significantly reduces the degree of delivery and consequently the power of the engine. It also causes an uneven idle of the engine and a low-speed operation and difficult also controlling the exhaust emissions.

It is therefore desirable additionally a valve control mechanism only for use with low engine speeds to provide which has a relatively short operation or opening period having.

Control systems for internal combustion engines with a variable valve timing are among others US 5287830 known.

at an internal combustion engine with a variable valve timing is it is necessary to monitor the function of this variable valve control at regular intervals. Well-known monitoring procedures In general, determine the position of a component, which to Adjusting the valve timing is used, therefore, the actual position to determine the valve timing. A monitoring method of this Art, however, provides only a general idea of how the Valve control is controlled at a given moment.

There a variable valve timing, such as the cam profile switching technology (CPS technique), in which different cam profiles are used to different Gas exchange characteristics for the cylinders of the engine at different operating conditions deliver a significant effect on the handling characteristics, exhaust emissions and having fuel economy, there is a need for an effective diagnostic method for identifying the system fault exhibit. The event of the valve lift can not be measured directly and special diagnostic algorithms, which are based on indirect information about The valve lift is required to be a fault in the System to determine.

Some Methods are known which allow the CPS state (cam profile switching state) capture. In US Pat. No. 6,213,068, the detection is based on Difference in the air charge or air filling, which in the cylinder for different Strokes is introduced. The introduced Air charge which by an air flow sensor of the elbow (MAF sensor) is measured with the air filling model based on the measured position of the throttle, the intake manifold pressure and the engine speed compared. The CPS state comes with the error between the measured and sampled air charge. A disadvantage of the method described in patent 6213,068 is that the procedure is no single fault detection of the cylinder allows. It is, however, for the fault detection the entire row of three cylinders suitable.

In US 6,006,152 For example, there is disclosed a method of monitoring the combustion condition using engine speed fluctuations. The method disclosed therein is based on the fact that the combustion state changes significantly during the switching of the valve mode of the engine. The combustion state is monitored by irregularities in the engine speed. The irregularities are associated with the CPS state. The method allows the single fault detection of the cylinder. The method uses a torque calculation method, which is well known in the literature, dedicated to the monitoring functions of the combustion efficiency, see for example US 4,532,592 and references in it.

Techniques discussed in the prior art documents set forth above allow the detection of the CPS state only during the steady state. The invention described in US Pat. No. 6,006,152 suggests detecting the average value of the unevenness of the engine speed fluctuations and comparing it with the reference average value of the unevenness. During the transition of the engine speed, the unevenness changes depending on the characteristics of the transition. The reference average value, which also depends on the characteristics of the transition, can not be determined for all transitions. This makes the method described in US Pat. No. 6,006,152 unsuitable for detecting the CPS state during transitions. Since the shift is likely to occur during the engine speed transitions, that provides in US 6,006,152 did not adequately detect the CPS state in all operating conditions of the engine.

It is worth noting that there are a number of prior art documents that have been disclosed in the field dedicated to detecting the combustion state of automotive engines via the measurements of engine speed fluctuations, such as US 4532798 . US 5539644 . EP 0437057 . EP 0609451 , In US 4532798 and US 5539644 Various methods are provided for measuring engine speed variations. The main attention, however, is given to the dependence of engine speed fluctuations on the road conditions. That is, the change in the engine speed has been investigated, which occurs according to the roughness and smoothness of the road surface. In EP 0437057 For example, there is proposed a method of measuring engine speed fluctuations taking into account the piston inertia of the pistons. The piston inertia has a significant effect on engine speed fluctuations only at high speeds, therefore, the inertia effect in the case of detecting the CPS state can be neglected because the cam profile is switched at relatively low engine speeds. It is worth noting that the combustion state monitoring techniques are used almost everywhere to detect the misfire (see, for example, FIG EP 0609451 and references therein).

at of the present invention which follows US Pat. No. 6,006,152, the combustion state of the engine is associated with the CPS state. Despite the fact that the misfire detection problem is not in the present invention the technique proposed here can be definitely applied, around the misfire detection problem while the transitions of Engine speed to solve.

EPIPHANY THE INVENTION

A The object of the invention is a method for monitoring the position of a variable valve control and in particular the detection of the CPS state while to the transitions too deliver.

This object is achieved by a method according to the characterizing portion of claim 1. The present invention is concerned with the transient detection of the position of a variable valve timing, and in particular the CPS position, using the unevenness of the rotational speed under the transient conditions. In this invention, a linear model for the crankshaft speed fluctuations is constructed during the transitions. The coefficients of the model are minimized by the Abstän de from the measured amplitudes to the model performances. The technique allows for CPS Fault Detection during engine speed transients via compensation of the transient component or transition component of the crankshaft speed fluctuations.

In preferred embodiments is the average of the relative distances, i. the distances of divided the measured amplitudes to the performances of the model by the performance of the model, which is calculated for each cylinder is for taken a number of cycles and compared with a reference value.

Further preferred embodiments are in the subclaims described.

A Another object of the invention is a device for monitoring the position of a variable valve timing in an internal combustion engine to deliver which to monitor the position of a variable valve timing and in particular detection during the CPS state arranged the transitions is. This object is achieved by a device that is available 8 is disclosed.

SHORT DESCRIPTION THE DRAWINGS

A embodiment The invention will be described in detail below with reference to the attached drawings become, in which:

1 FIG. 4 is a graph showing fluctuations in engine speed and crankshaft speed in a transient condition; FIG.

2 Figure 12 shows a graph of crankshaft speed fluctuations, a particular linear model of a transition, and the relative distances between the amplitudes of the fluctuations and the linear model for a set of combustion counts in a transient condition;

3 shows a graph of relative average amplitude as a function of cycle number;

4 shows a relative average amplitude for individual cylinders,

5 shows a performance index, which in US 6,006,152 is proposed as a function of the number of cycles,

6 shows an engine speed fluctuation in an interval in which the relative distance has a large value,

7 FIG. 2 is a schematic diagram of an internal combustion engine having a variable valve timing controller and a control device constructed therefor according to preferred embodiments of the present invention; FIG.

8th FIG. 4 is a side cross-sectional view of a valve lifter and valve assembly which may be used in conjunction with the invention to provide first and second cam profiles; and FIG

9 shows a flowchart of a method for monitoring the position of a variable valve timing in an internal combustion engine having a plurality of cylinders.

EMBODIMENT (S) OF THE INVENTION

First, a theoretical background of the invention with respect to 1 - 6 to be discribed.

It is known to change the time rate the angular velocity of the crankshaft to pure torque which is proportional to the system divided by the moment of inertia J. acts.

proportional, wobei Te das durch den Motor erzeugte Drehmoment durch alle Zylinder zur Zeit t und Tl das Drehmoment der Motorlast ist. Durch das Integrieren zwischen den Zeiten, bei welchen die Motordrehzahl minimal wird, und den Höchstwerten jeweils für einen einzigen Zylinder, dessen Verbrennungstakt im Intervall auftritt, erhält man

wobei A_i die Kurbelwellengeschwindigkeitsfluktuation über dem Zeitintervall [ts tf] ist, wobei ts die Anfangszeit des Intervalls und tf die Endzeit ist. Diese Fluktuation A_i ist der Messwert des reinen Motordrehmoments über dem involvierten Intervall.The angular acceleration is to break

proportional, where Te is the torque produced by the engine through all cylinders at time t and Tl is the torque of the engine load. By integrating between the times when the engine speed becomes minimum and the maximum values each for a single cylinder whose combustion stroke occurs in the interval, one obtains

where A _{i is} the crankshaft speed fluctuation over the time interval [ts tf], where ts is the start time of the interval and tf is the end time. This fluctuation A _i is the measured value of the pure engine torque over the interval involved.

The Eq. (E1) leaves determining the average value of the torque generated by the cylinder to, whose combustion cycle occurs in the interval.

wobei A die durchschnittliche Amplitude der Motordrehzahlfluktuationen über den Motorzyklus für alle N Zylinder, Ai die durchschnittliche Amplitude der Motordrehzahlfluktuationen für die Zylinder i über die Anzahl an Zyklen nc, j = 1, ..., nc die Zyklusanzahl ist.Ideally, in the steady state operation, the speed fluctuation is the same for all cylinders because the speed waveform is uniform. For the real motor, however, even in steady state, the wave amplitudes are not exactly the same. In order to obtain a ratio for the average torque generated by the engine over all cylinders, the average of the shaft amplitude can be taken over the engine cycle. In order to obtain a ratio for the average torque generated by the cylinder numbered i during a number of cycles n _c , the average of the shaft amplitude may be taken over the number of cycles involved, ie

in which A the average amplitude of the engine speed fluctuations over the engine cycle for all N cylinders, Ai the average amplitude of the engine speed fluctuations for the cylinders i over the number of cycles nc, j = 1, ..., nc is the cycle number.

In the method which is in US 6,006,152 is disclosed, the comparison of the average values calculated by the formulas (E2) and (E3) with the reference values depending on the speed and load is proposed with the intention of detecting the CPS state. For the steady state operation, the engine speed remains constant over the engine cycle and the crankshaft speed fluctuations are approximately the same. On the contrary, the speed fluctuations due to the changing average speed during the engine transitions differ from the steady state fluctuations.

Therefore are the values of the crankshaft speed fluctuations of the transition not in the calculation of the average amplitudes by using of the formulas (E2) and (E3) and can not be included.

By The use of a method according to the invention can be the information about the CPS position, however, still from the crankshaft speed fluctuations be removed. For this, the average speed during the transitions should be off the performance indices are removed by the averages which are calculated by the formulas (E2) and (E3) were.

at In the present invention, performance indexes are used instead of Formulas (E2) and (E3) are proposed, which allow the transition detection of the CPS disorder. This is done by removing an average transition component obtained from the indexes obtained by the functions (E2) and (E3).

In the first step, the model of crankshaft speed fluctuations is constructed. this happens by assigning a function representing a transient component of the engine speed fluctuation over the at least one engine cycle, the function being represented by a set of model coefficients.

moreover be for a given engine cycle N values of crankshaft speed fluctuation Ai, i = 1, ... N measured.

In a preferred embodiment, the assigned function will be linear. By assuming the linearity of the model of crankshaft speed fluctuations, one obtains y i = c 0 + c 1 x i (E4), where y _{i is} the model power of the crankshaft speed fluctuations, c ₀ and c _{1 are} the model coefficients, and x _i = 1, ... N is the number of amplitude of the fluctuation within the cycle.

wird in Bezug auf die Modellkoeffizienten c₀ und c₁ minimiert, wobei j = 1, ..., nc die Zyklusanzahl ist.The following sum:

is minimized with respect to the model coefficients c ₀ and c ₁ , where j = 1, ..., nc is the cycle number.

The minimization problem mentioned above is a well-known least squares curve fitting problem and can be solved by equating the partial derivatives of 1 _j to zero with respect to c ₀ and c ₁ , ie!

The last two equations are solved with respect to c ₀ and c ₁ for each engine cycle.

The solution to the minimization problem leads to a first performance index, according to the following: k i = A i - (c 0 + c1x i ) (E5A).

The coefficient c ₀ represents the offset value of the amplitude of the fluctuations and the coefficient c ₁ is the tangent of the angle which directly reflects the character of the transition. The model (E4) can be seen as a model of the average of crankshaft speed fluctuations. In steady state, the average value of the fluctuations is constant and c _{1 is} approximately zero. On the contrary, the average value of the crankshaft speed fluctuations changes among the transitions within the cycle and can be approximated well by the model (E4).

It It is worth noting that polynomials of a higher order are for modeling the crankshaft speed fluctuations can be used (E4). The model could using information from different engine cycles be formed. In the embodiment disclosed herein, the simplest becomes Case in consideration drawn.

wobei i = 1, ..., N; N die Anzahl an Zylinder ist.The next step is to calculate the relative distances between the amplitudes of the fluctuations and the performances of the model (E4). The relative distances can be used as a second performance index. These distances do not depend on the transition and can be calculated as follows

where i = 1, ..., N; N is the number of cylinders.

wobei d die relative Durchschnittsamplitude der Abweichung der Motordrehzahlfluktuationen vom durchschnittlichen Modell über den Motorzyklus für alle N Zylinder ist, di die relative Durchschnittsamplitude der Abweichung der Motordrehzahlfluktuationen vom durchschnittlichen Modell für den Zylinder i über die Anzahl von Zyklen nc, j = 1, ..., nc die Zyklusanzahl ist.A third and fourth performance index can be obtained by rewriting the performance indices (E2) and (E3), which are given by US 6,006,152 be proposed. The following third and fourth performance index are obtained:

in which d is the relative average amplitude of the deviation of the engine speed fluctuations from the average model over the engine cycle for all N cylinders, di the average relative amplitude of the deviation of the engine speed fluctuations from the average model for the cylinder i over the number of cycles nc, j = 1, ..., nc is the cycle number.

Of the fundamental difference between the indices (E2), (E3) and (E7), (E8) is that (E7) and (E8) are the relative averages of Deviation of the amplitude from the linear model of the fluctuations in Calculate cycle, i. remove the effect induced by the engine speed transients becomes.

A preferred embodiment a CPS fault detection algorithm can be summarized as follows:

Step 1

Calculate the difference Ai between the instantaneous engine speed, where it gets minimum or maximum values for a single cylinder whose combustion cycle occurs in the interval. In 1 For example, the engine speed (RPM) for a single cycle is plotted on Volvo's five-cylinder engine with a line marked + sign, and Ai is the difference between the dashed lines.

step 2

Compute the coefficients c ₀ and c _{1 of} the model y i = c 0 + c 1 x i (E9) for each engine cycle by minimizing the cost function (E5). The amplitudes Ai (rpm) as a function of the number of combustion are in 2 graphically represented by a line marked with a + sign. The power y _{i of} the model (E9) is graphically represented by a dashed line.

step 3

wobei x_j = 1, ..., N die Verbrennungsanzahl im Zyklus ist.Calculate the relative distances between the amplitudes and fluctuations of the model (E9).

where x _j = 1, ..., N is the number of burns in the cycle.

The relative distance d _i (percent) as a function of the number of cycles is in 2 graphically represented by a line marked with o characters.

Step 4

Compute the average amplitude of the relative deviation of the engine speed fluctuations from the average model over the engine cycle for all N cylinders and the relative average amplitude of the deviation the engine speed fluctuations from the average model for the cylinder i over the number of cycles nc:

The relative average amplitude d (Percent) as a function of a number of cycles is in 3 shown graphically. The relative average amplitude for the cylinder i, di , i = 1, ..., 5 is in 4 represented graphically, where d1 one with the reference 1 marked line, d2 one with the reference 2 marked line, d3 one with the reference 3 marked line, d4 one with the reference 4 marked line and d5 one with the reference 5 marked line is.

, i = 1, ..., 5, welcher in US 6 006 152 als Funktion einer Zyklusanzahl vorgeschlagen wurde, ist in 5 grafisch dargestellt. Die Figur zeigt, dass der Index (E3) nicht zur Verwendung während dem Übergang (den ersten 20 Zyklen) geeignet ist. Während dem Übergang weist der Performance Index (E3) trotz ziemlich gleichen Verbrennungen zu hohe Werte auf.The Performance Index (E3)

, i = 1, ..., 5, which in US 6,006,152 was suggested as a function of a number of cycles is in 5 shown graphically. The figure shows that the index (E3) is not suitable for use during the transition (the first 20 cycles). During the transition, the performance index (E3) is too high despite fairly similar burns.

Step 5

wobei d₀₁ und d₀₂ Referenzwerte sind, welche Funktionen der Motordrehzahl und Last sind.Compare the values calculated in the previous step with the reference values stored in memory.

where d ₀₁ and d _{02 are} reference values which are functions of engine speed and load.

3 shows the highest value that the performance index (E11) has in the cycle 28 receives. The engine speed for the cycle 28 is in 6 graphically showing significant combustion irregularities in the cycle.

7 shows in schematic form an internal combustion engine 1 , which with a variable valve control 2 Is provided. According to a preferred embodiment, the variable valve timing is 2 arranged to gas exchange in or out of a variety of cylinders 3 of the internal combustion engine 1 by selecting the camshaft profile of a camshaft 4 to control. The camshaft 4 has a first cam having a first cam profile and a second cam having a second cam profile which is larger than the first cam profile, as will be described in greater detail below. The variable valve control 2 includes a drive device 5 which is controlled by an electronic control unit 6 is controlled. The drive device 5 maneuvers the camshaft to adjust which cam profile is currently on the lift mechanisms 7 for the gas exchange valves 8th acts. The variable valve control, which is arranged on the inlet valve in the embodiment shown, can also be arranged on the outlet valve.

The invention is also for variable valve timing 2 applicable, which is arranged to the position of the camshaft 4 to control which in relation to the angular position of a camshaft 8th by means of an adjustment is variable.

The adjustment device 5 to change the camshaft mode is controlled by a valve control unit 10 controlled, which in the electronic control unit 6 is arranged. The control is performed in a manner known to one of ordinary skill in the art to provide switching of the camshaft mode in response to the operating condition of the engine.

The electronic control unit 6 also includes a calculation device 11 and a monitoring device 12 , The calculation device 11 and monitoring device 12 form together with the camshaft sensor 9 , which in this case acts as a scanning device to unevenness of the rotational speed of the camshaft 8th to detect a device for monitoring the position of the variable valve timing 2 ,

The calculation device 11 receives from the camshaft sensor 9 a signal which is the angular position of the camshaft 8th equivalent. In the present embodiment, this signal consists of a pulse train, each pulse corresponding to a certain portion of an angle passing through the camshaft 8th was scanned. At a certain position of the camshaft is a mark 13 made, which generates a special pulse and therefore allows to determine the absolute position of the camshaft.

The calculation device 11 includes a device 13 for measuring the engine speed over at least one engine cycle for all cylinders. The measurement is performed in a manner known to one skilled in the art by performing a time derivative of the angular position provided by the camshaft sensor.

The calculation device 11 also includes a facility 14 for determining the engine speed fluctuations for the respective cylinder as a difference between the maximum and minimum engine speeds at a time interval including the combustion stroke of the respective cylinder. The maximum and minimum values are obtained in a known manner from the variation of the sampled values of the engine speed. The scanned values vary in a way as in 1 shown. The maximum and minimum values are stored in memory 15 stored, which is arranged in the calculation device.

The calculation device 11 also includes a device 16 for assigning a function representing a transient component of the engine speed fluctuation over at least one engine cycle, the function being represented by a set of model coefficients. The device 16 for assigning a function may be arranged by a memory area in which the model coefficients are stored. The form of the function will be decided upon implementing the controller by deciding which form should have the function. In a preferred embodiment, it is selected that the function is a linear model.

The computing device also includes a device 17 for determining the model coefficients. The device for determining the model coefficients is preferably formed by a device for minimizing a cost function for the particular engine speed fluctuations for the respective cylinder with respect to the function representing a transition component and thereby determining the model coefficients. The device 17 to minimize the cost function is formed by a least squares fitment adaptation device of a function to the set of values that are stored in memory 15 stored maximum and minimum values and possibly all sampled values of the engine speed. The device for adapting the least squares method is well known to someone with technical abilities. The cost function has the field of view shown in equation (E5).

The monitoring device 12 includes a device 18 for calculating the distance between the determined engine speed fluctuations and a value of the function representing a transient component corresponding to the respective particular engine speed fluctuation, wherein a first performance index is obtained. The distance is calculated according to the formula (E5A).

In a preferred embodiment, the device includes 12 for monitoring also a device 19 for determining a relative distance between the determined engine speed fluctuations and the value of the function representing a transient component with respect to the value of the function representing a transient component which is at a particular engine speed on, for use as a second performance index. The relative distance is determined according to the formula (E6).

In yet a preferred embodiment, the device includes 12 for monitoring also a device 20 for computing an average amplitude of the relative distance over a motor cycle, the average amplitude being used as the third performance index. The average amplitude is determined according to the formula (E7).

In yet another preferred embodiment, the device includes 12 for monitoring also a device 21 for calculating an average amplitude of the relative distance for the respective cylinder over a number of engine cycles, the average amplitude being used as the fourth performance index. The average amplitude for each cylinder is determined according to the formula (E8).

The device 12 for monitoring also includes a device 22 to compare at least one of the performance indices with those in a memory 23 stored reference values. The comparison is made according to the formulas (E11) and (E12). At the event that the performance indices exceed the reference values, an indication is given that the correct valve mode is not actuated.

The device 22 For comparing the performance indices with the reference values, means for determining which of a first cam having a first cam profile and a second cam having a second cam profile which is larger than the first cam profile currently acts on the gas exchange valve lift mechanisms at the event in that the device according to the invention is used to monitor a CPS engine.

All the different devices used in the device 11 for calculating and the device 12 for monitoring are formed by programs running in a microcontroller with a processor and memory areas. The microcontroller is programmed to execute the computation of formulas (E5) - (E12) through the use of information provided by the engine speed sensor 9 to be delivered.

In 8th For example, a valve assembly is shown which may be used in conjunction with the invention to provide two different cam modes.

In relation to 8th becomes a valve 110 with a plate 111 shown which is movable in the axial direction to the passage 105 seal. The valve 110 is lubricious in a hole 112 in the cylinder block 113 attached and goes through a cavity 114 , In the cavity 114 around the valve 110 there is a spring 115 wherein the one end thereof is at an underside of the cavity 114 abuts and the other end of the same in a valve 110 attached approach or edge 116 located to the valve 110 generally bias in one direction upwards.

At the upper end of the valve 110 there is a ram assembly 118 , The ram assembly 118 has a coaxial, inner plunger 120 and an outer plunger 121 on. The inner plunger rests on a hydraulic lash adjuster 122 a known type, which in turn on the upper end of the valve 110 supports. The ram assembly 118 is inside the hole 119 slidably attached, extending from the cavity 114 to the top of the cylinder block 113 extends. A cylinder head cover may be above the top of the cylinder block 113 be positioned and securely attached to the same.

Above the cylinder block 113 there is a rotatable camshaft 130 which in the usual arrangement 131 can be driven, which has a pair of outer cam lobes 126 between which there is a central cam hump 123 located. The middle cam hump 123 has a profile designed to optimize engine performance over a selected portion of engine speed and load range. Although the middle cam hump is 123 Fig. 1 illustrates a generally eccentric shape, but it is intended that this cam lobe may have a circular shape which permits deactivation of the valve while under the control of this cam lobe. The outer cam hump 126 have a substantially identical profile to each other and are designed to optimize engine performance over another portion of the engine speed and load range.

The camshaft 130 is arranged such that in low-speed conditions top 120a of the inner plunger 120 through the middle cam hump via a drag lever 124 is driven. The top 121 of the outer plunger 121 gets in contact with the outer cam lobes 126 by means of a spring 125 held, which coaxially around the spring 115 is positioned and located at one end in the recesses 132 in the lower end surface of the outer plunger 121 located. At the lower end of the same supports the spring 125 on the bottom of the cavity 114 ,

The selection of the cam profile is made either by connecting the inner plunger 120 and outer plunger 121 such that they move together, which allows the outer plunger 121 and the outer cam lobes 126 the valve 110 control, or by separating the inner plunger 120 and outer plunger 121 achieves what allows the inner pestle 120 and the inner cam hump 123 the valve 110 Taxes.

In 9 A flowchart of a method of monitoring the position of variable valve timing in a multiple cylinder engine is shown.

In a first step 210 In the method, the engine speed is measured over at least one engine cycle for all cylinders included in the plurality of cylinders.

In a second step 211 According to the method, the engine speed fluctuations for the respective cylinder are determined as a difference between the maximum and minimum engine speeds at a time interval including the combustion stroke of the respective cylinder.

In a third step 212 The method assigns a function representing a transition component of the engine speed fluctuation over the at least one engine cycle. The function is represented by a set of model coefficients.

In a fourth step 213 The method determines the model coefficients, ie the coefficients for the assigned function. This is preferably done by minimizing the cost function for the particular engine speed fluctuations for the particular cylinder with respect to the function representing a transitional component.

In a fifth step 214 according to the method, calculating the distance between the determined engine speed fluctuations and a value of the function representing a transient component corresponding to the respective particular engine speed fluctuation, thereby obtaining a first performance index.

optional become further performance indices in further process steps calculated as disclosed below.

In a sixth step 215 According to the method, a relative distance between the determined engine speed fluctuations and the value of the function representing a transient component with respect to the value of the function representing a transient component corresponding to the respective particular engine speed fluctuation is determined for use as the second performance index.

In a seventh step 216 The method calculates an average amplitude of the relative distance over a motor cycle, using the average amplitude as the third performance index.

In an eighth step 217 According to the method, an average amplitude of the relative distance for the respective cylinder over a number of engine cycles is calculated, the average amplitude being used as the fourth performance index.

In a ninth step 218 According to the method, at least one of the performance indices is compared with the reference values stored in a memory.

The Invention should not be limited to the embodiments disclosed above limited but can be within the range of the attached claims changed become.

Claims (18)

Method for monitoring the position of a variable valve control ( 2 ) in an internal combustion engine ( 1 ), which has a plurality of cylinders ( 3 ), with the following steps: measuring ( 210 ) an engine speed over at least one engine cycle for all cylinders ( 3 ) included in the plurality of cylinders, determining ( 211 ) of engine speed fluctuations (A _i ) for respective cylinders as the difference between a maximum and a minimum engine speed in a time interval including the working stroke of the respective cylinders, characterized in that the method includes the further steps of: allocating ( 212 ) a function (E4) representing a transient component of an engine speed fluctuation (A _i ) over the last engine cycle, the function being represented by a set of model coefficients, determining ( 213 , E5) of the model coefficients and calculating ( 214 , E5A) of the distance (k _i ) between the predetermined engine speed fluctuations (A _i ) and a value of the function (E4) representing a transient component corresponding to a corresponding determined engine speed fluctuation (A _i ). Method according to claim 1, characterized in that the model coefficients are determined by minimizing a cost function (E5) for the determined engine speed fluctuations (A _i ) for a corresponding cylinder with respect to the function (E4) representing a transient component. Method according to one of claims 1 or 2, characterized in that as a first performance index the distance (k _i ) between the determined engine speed fluctuations (A _i ) and a value of the function (E4) is used, which represents a transient component, which with corresponding corresponding engine speed fluctuations (A _i ). Method according to one of claims 2 or 3, characterized in that, for use as the second performance index, a relative distance (d _i ) between the determined engine speed fluctuations (Ai) and the value of the function (E4) representing a transient component with respect to to the value of the function (E4) representing a transient component corresponding to the corresponding particular engine speed fluctuation is determined. A method according to claim 4, characterized in that an average amplitude d of the relative distance (d _i ) over an engine cycle is calculated (E7), wherein the average amplitude is used as the third performance index. A method according to claim 4 or 5, characterized in that an average amplitude di the relative distance (d _i ) over a number of engine cycles for a corresponding cylinder is calculated (E8), the average amplitude being used as the fourth performance index. Method according to one of the preceding claims, characterized in that at least one of the performance indices with reference values is compared, which are stored in a memory. Method according to one of the preceding claims, characterized in that at least one of the performance indices is used for determining which of a first cam ( 123 ), which has a first cam profile, and a second cam ( 126 ), which has a second cam profile, which is larger than the first cam profile, at the moment on a lifting mechanism ( 7 ) for gas exchange valves ( 8th ), which are arranged to control a gas exchange in or out of the plurality of cylinders. Method according to one of the preceding claims, characterized in that the function (E4), which represents a transient component of the engine speed fluctuation over the at least one engine cycle, is expressed as f = c ₀ + c ₁ x _i , where c ₀ and c _{1 are} model coefficients and x _{i is} the number of the amplitude of the fluctuation within a motor cycle. Device for monitoring the position of a variable valve control ( 2 ) in an internal combustion engine ( 1 ), which has a plurality of cylinders ( 3 ), comprising: a device ( 13 ) for measuring an engine speed over at least one engine cycle for all cylinders included in the plurality of cylinders, An institution ( 14 ) for determining engine speed fluctuations (A _i ) for respective cylinders ( 3 ) as the difference between a maximum and a minimum engine speed in a time interval including the working stroke of the respective cylinders, characterized in that the apparatus further comprises: means ( 16 ) for assigning a function (E4) representing a transient component of engine speed fluctuations (A _i ) over the at least one engine cycle, the function (E4) being represented by a set of model coefficients, means ( 17 ) for determining the model coefficients and a device ( 18 ) for calculating the distance (k _i ) between the determined engine speed fluctuations (A _i ) and a value of the function (E4) representing a transient component that corresponds to the respective determined engine speed fluctuations (A _i ). Apparatus according to claim 10, characterized in that the device ( 17 ) for determining the model coefficients includes means for minimizing a cost function (E5) for the determined engine speed fluctuations (A _i ) for a corresponding cylinder with respect to the function (E4) representing a transient component. Device according to one of claims 10 or 11, characterized in that as the first performance index the difference (k _i ) between the determined engine speed fluctuations (A _i ) and a value of the function (E4) is used, which represents a transient component associated with a corresponding particular engine speed fluctuation (A _i ) corresponds. Apparatus according to claim 12, characterized in that the device further comprises a device ( 19 ) for determining (E6) a relative distance (d _i ) between the determined engine speed fluctuations (A _i ) and the value of the function (E4) representing a transient component with respect to the value of the function (E4) representing a transient component which corresponds to a corresponding particular engine speed fluctuation (A _i ) for use as a second performance index. Apparatus according to claim 13, characterized in that the apparatus further comprises a device ( 20 ) for calculating (E7) a mean amplitude ( d ) of the relative distance (d _i ) over an engine cycle, the average amplitude being used as the third performance index. Apparatus according to claim 13 or 14, characterized in that the apparatus further comprises a device ( 21 ) for calculating (E8) a mean amplitude ( di ) of the relative distance (d _i ) over a number of engine cycles for a corresponding cylinder, the average amplitude being used as the fourth performance index. Device according to one of claims 12 to 15, characterized in that the device further comprises a device ( 22 ) for comparing at least one of the performance indices with reference values stored in a memory. Device according to one of claims 12 to 16, characterized in that the device further comprises: means for determining ( 22 ), which from a first cam ( 123 ), which has a first cam profile, and a second cam ( 126 ), which has a second cam profile, which is larger than the first cam profile, at the moment on lifting mechanisms ( 7 ) for gas exchange valves ( 8th ) acting to control gas exchange into or out of the plurality of cylinders ( 3 ), wherein a comparison of at least one of the performance indices is used for determining with a reference value stored in a memory. Device according to one of claims 12 to 17, characterized in that the function (E4) representing a transient component of the engine speed fluctuations (A _i ) over the at least one engine cycle is expressed as f = c ₀ + c ₁ x _i c ₀ and c _{1 are} model coefficients and x _{i is} the number of amplitude of the fluctuation within a motor cycle.