DE102020207175B3 - Method for determining a camshaft position of an internal combustion engine - Google Patents

Abstract

Method for determining an intersection point (23) of at least two point clouds (17, 22), wherein each point cloud (17, 22) comprises a plurality of points (18, 36), each point (18, 36) by a plurality of coordinates (37, 38, 39) is defined and thus has a defined position in a multi-dimensional coordinate system (40).

Description

The present invention is directed to a method for determining a camshaft position of an internal combustion engine.

Modern internal combustion engines - such as gasoline engines - are constantly being further developed. An essential part of the improvements in consumption and emissions behavior is achieved through needs-based and energetically efficient metering of the cylinder charge (as a mixture of fresh air and residual gas). The charge exchange control organs play an important role here, since both the total charge mass and the composition (residual gas) can be adapted as required over a wide range, in particular through phase control of the intake and exhaust camshafts. The effect or the lever on the main parameters of the combustion (total charge mass and residual gas fraction) through the phase control (in more complex systems also lift curve control such as ACT or ACT + via AVS) depends essentially on the current marginal parameters of the external gas system of the internal combustion engine. In addition to the passive ambient conditions such as ambient pressure and temperature, the "offered" intake manifold pressure on the intake side of the internal combustion engine as a combination of charging (VTG position, exhaust gas enthalpy) and throttling (throttle valve) and the "offered" scavenging gradient between exhaust gas back pressure on the exhaust side of the internal combustion engine are particularly important and intake manifold pressure as a driver for metering the internal residual gas mass relevant for the effect or the lever of the phase control. Depending on the resulting pressure conditions in the intake manifold on the intake side and in the exhaust manifold on the exhaust side, the control of the phase positions of the intake and exhaust camshafts, i.e. the timing of the intake and exhaust valves, must be adapted to these conditions.

The aim is to optimize this interaction even in dynamic operation of the internal combustion engine and to dose it in situ so that minimal consumption is achieved with acceptable driving behavior. Consequently, the optimal conditions are in the range of the smallest possible pressure differences (small reserves: throttle valve and flushing gradient), since unnecessarily high pressure levels mean energy expenditure which is then not used for propulsion (technical work). Optimizing the gas exchange leads, for example, to metering the residual gas mass (or the internal EGR) with the lowest possible purging gradient. Since the mass flows are always driven by the pressure gradient, the fine metering and control takes place via the geometric path (effective cross-sectional area). The change in the geometric parameters (in this example valve lift curves via phase position) in pressure differential situations close to the pressure equalization then has a very large leverage on the target variables. In other words: The system is preferably operated in a very sensitive area with the optimization target “Consumption”, in which the geometric parameters have massive effects on the overall process.

In this situation it is increasingly important to know the exact absolute geometric properties of the system (of each individual pattern). For phase control, in addition to the geometrical manufacturing accuracy of valves, camshafts, etc., this is particularly also the positioning of the camshafts in relation to the crankshaft and the assembly of the encoder wheels including the sensors. In modern internal combustion engines, the installation situation of this system is measured at the end of production and assigned to the respective components. These specific installation values are read into the engine control unit and taken into account when the engine is running when determining the positions of the intake and exhaust camshafts. As long as the installation situation is not disturbed by wear and tear or maintenance, the position of the camshafts can be identified very precisely. If components are replaced, the specific installation values of the new part must be transferred to the control unit after the work has been completed. If components were not exchanged properly, the positioning of the camshafts might not correspond to physical reality and the operation of the vehicle would be impaired to the extent that the optimum consumption and emission values can no longer be achieved. In order to prevent this, the unqualified exchange of components could be mechanically prevented. Another alternative would be a method that can recognize, monitor and, if necessary, adapt the physical reality during operation of the internal combustion engine.

One approach for this alternative is to detect the pulsating pressures in the intake and / or exhaust manifold, i.e. in the intake or exhaust side of the internal combustion engine, and to apply them to the positions or phase positions of the intake and exhaust camshafts on the basis of the measured pressure signal shut down. The following relationship results as a simplified chain of effects: The crankshaft drive with piston and crankshaft generates a cylinder volume that varies cyclically in the combustion cycle. This is short-circuited via the open valves (i.e. the valve lift curve) with the adjacent volumes of the intake manifold or inlet side and exhaust manifold or outlet side. The respective valve lift curve is shifted in its phase via the phase adjustment, the pressures in both Volumes therefore change according to the position of the valve stroke curves relative to the piston movement. By measuring these pressures, independent of the position measurement of the camshafts, a second piece of information about the interaction of the valve lift profile and the cylinder volume is obtained. Assuming precisely manufactured camshaft shapes, cylinder geometries and minimally varying valve clearances, the phase positions of the camshafts dominate certain aspects in the selected pressure signals.

The accuracy of the detection of the camshaft phase positions depends on other operating parameters such as B. speed, ambient pressure, VTG and throttle position, as well as a possible combustion of the fuel-air mixture. If necessary, these must be set reproducibly within a narrower framework for the phase detection. As a result, the detection is not permanent, but only under certain selected conditions, e.g. B. in certain operating points can take place. The position sensors and encoder wheels of the internal combustion engine, e.g. B. sensors for detecting the phase positions of the crankshaft and camshaft, can not be saved in this scenario.

From the DE 10 2015 209 665 A1 It is known to measure dynamic pressure oscillations in the intake and / or exhaust tract and to determine a crankshaft position or camshaft position feedback signal. From the pressure oscillations and the crankshaft signals, the phase angle of selected signal frequencies of the pressure oscillations can be determined by discrete Fourier transformation. These phase angles can be compared with reference phase angles and reference valve control times, so that valve control times can be determined for the internal combustion engine in question.

From the DE 10 2016 219 582 B3 It is known to measure dynamic pressure oscillations for an operating point in the intake and exhaust tract and to determine a crankshaft position or camshaft position feedback signal. From the pressure oscillations and the crankshaft signals, the amplitudes of selected signal frequencies of the measured pressure oscillations can be determined by discrete Fourier transformation. It is taken into account here that the amplitudes of the individual selected signal frequencies, i.e. the deflection height of the pressure oscillation signal in relation to a center line, and the crankshaft phase angle signal are dependent on the intake valve lift phase difference or phase position and the exhaust valve phase difference or phase position . Based on the determined amplitudes of the respective selected signal frequencies, contour lines of the same amplitude, which are dependent on the intake valve lift phase difference and the exhaust valve lift phase difference, are determined in characteristic maps, these characteristic fields being determined on a reference engine for these signal frequencies. These contour lines of the same amplitude of the selected different signal frequencies are projected into a common plane spanned by the intake valve lift phase difference and the exhaust lift phase difference. Points of intersection of these contour lines result in specific values for the intake valve lift phase difference or phase position and the exhaust lift phase difference or phase position.

In the DE 10 2016 219 582 B3 two signal frequencies are evaluated, which were determined in the course of a measurement, so in an operating point of the internal combustion engine, so z. B. the signal frequencies of a pressure signal in the intake tract and / or in the outlet tract. Since the stability and robustness of the process z. B. depends on the intersection angle of the contour lines, no high accuracy of the values determined for the actual phase position can be determined for operating points in which the determined pressure signals do not have clearly different inclined contour lines.

It is the object of the present invention to at least partially solve the problems cited with reference to the prior art. In particular, a more robust and stable determination of the actual phase positions of camshafts is to be made possible.

A method with the features according to patent claim 1 contributes to the solution of these objects. Advantageous further developments are the subject of the dependent claims. The features listed individually in the patent claims can be combined with one another in a technologically sensible manner and can be supplemented by explanatory facts from the description and / or details from the figures, with further design variants of the invention being shown.

The method proposed here is aimed at determining an intersection point of at least two point clouds. Each point cloud comprises, in particular, a plurality of points, each point being defined by a plurality of coordinates (at least two coordinates or dimensions, possibly more; e.g. first coordinate - e.g. x coordinate: actual intake camshaft phase position , second coordinate - e.g. y-coordinate: actual exhaust camshaft phase position, third coordinate - e.g. z-coordinate: e.g. characteristic of the pressure signal, etc.) is defined and thus a defined position in a multidimensional Coordinate system, e.g. B. in a surface or in a room or in another multi-dimensional coordinate system.

1. I. Bestimmen einer ersten Punktewolke mit einer Mehrzahl von ersten Punkten,
2. II. Bestimmen einer zweiten Punktewolke mit einer Mehrzahl von zweiten Punkten, wobei jeder Punkt durch eine Mehrzahl von Koordinaten definiert ist und damit eine definierte Position in einem mehrdimensionalen Koordinatensystem aufweist;
3. III. Zuordnen eines Werts 1 für jeden Punkt jeder Punktewolke und Zuordnen eines Werts null für jede andere Position in dem Koordinatensystem,
4. IV. Addieren der ersten Punktewolke und der zweiten Punktewolke und Ermitteln einer Schnittmenge der Punktewolken, wobei die Schnittmenge durch mindestens einen Schnittpunkt gebildet ist, der in dem Koordinatensystem an einer Position angeordnet ist, die einen Schwellwert von mindestens 2 beträgt.

In particular, the method comprises at least the following steps:

1. I. determining a first point cloud with a plurality of first points,
2. II. Determining a second point cloud with a plurality of second points, each point being defined by a plurality of coordinates and thus having a defined position in a multidimensional coordinate system;
3. III. Assigning a value 1 for each point of each point cloud and assigning a value zero for every other position in the coordinate system,
4. IV. Adding the first point cloud and the second point cloud and determining an intersection of the point clouds, the intersection being formed by at least one intersection which is arranged in the coordinate system at a position which is a threshold value of at least 2.

The above, in particular not conclusive, classification of the procedural steps in I. to IV. Is primarily intended only to serve as a distinction and not to enforce a sequence and / or dependency. The frequency of the process steps z. B. during setup and / or operation of the system may vary. It is also possible that process steps overlap one another at least partially in time. Process steps I. and II. Very particularly preferably take place simultaneously in each case. In particular, step III. after steps I. to II., if necessary at least temporally overlapping with steps I. and II. In particular, step IV. takes place after step III. instead of, possibly at least temporally overlapping, at least with step III. In particular, steps I. to IV. Are carried out in the order listed.

The point of intersection of two curves or functions is usually determined by forming the values of both curves at common interpolation points in a main direction (e.g. x-direction). The difference between the two values results in a curve, the zeros of which represent the intersection points of the two curves. For this purpose, both curves in the main direction must have a unique result. If one of the curves in the main direction is not strictly monotonous and unambiguous, there would be more than one corresponding y-value for an x-value. This means that intersections cannot be determined for all sub-areas of the curves.

The method described here is intended in particular to make it possible to determine an intersection (that is to say one or more intersection points) of these data sets even for data sets (point clouds) that cannot be described by curves or functions.

The data sets (point clouds) considered here have in particular at least partially non-continuous points forming a line (which can be described by a function or a curve. The data sets considered here are composed in particular of at least partially individually determined value pairs (with two to n coordinates), i.e. points together that represent the relationship under consideration as a point cloud. The points of each point cloud therefore do not necessarily have to be arranged adjacent to one another, but can also be distributed in islands or areas. Several points with different The method forms points of intersection of these point clouds, whereby the point clouds can in particular form several points of intersection which form the set of intersections.

The method is used in particular to determine a combination of an actual intake camshaft phase position of an intake camshaft and an actual exhaust camshaft phase position of an exhaust camshaft of a series internal combustion engine. The method can be carried out during operation of the series internal combustion engine. The respective actual phase position of the camshafts can be determined in relation to an operating point of the series internal combustion engine.

1. a) Bestimmen von Modellen an einer Referenz-Verbrennungskraftmaschine für verschiedene Betriebspunkte, wobei jedes Modell für jeweils einen Betriebspunkt der Referenz-Verbrennungskraftmaschine einen Zusammenhang zwischen einem an der Referenz-Verbrennungskraftmaschine ermittelten Drucksignal (bzw. mindestens einem Merkmal eines Drucksignals) in Abhängigkeit von der Ist-Einlassnockenwellen-Phasenlage und der Ist-Auslassnockenwellen-Phasenlage des jeweiligen Betriebspunkts darstellt;
2. b) Anfahren eines ersten Betriebspunkts mit der Serien-Verbrennungskraftmaschine und Erfassen (z. B. Messen) eines ersten Drucksignals bei einer (angenommenen) ersten Einlassnockenwellen-Phasenlage und einer (angenommenen) ersten Auslassnockenwellen-Phasenlage und Bestimmen eines ersten Merkmals aus dem ersten Drucksignal;
3. c) Bestimmen der ersten Punktewolke gemäß Schritt I., wobei die einzelnen ersten Punkte der ersten Punktewolke durch die aus den Modellen abgeleiteten Kombinationen der Ist-Einlassnockenwellen-Phasenlage und der Ist-Auslassnockenwellen-Phasenlage für das in Schritt b) bestimmte erste Merkmal gebildet werden;
4. d) Bestimmen eines zweiten Merkmals (insbesondere ein anderes Merkmal als das erste Merkmal) aus dem ersten Drucksignal oder Anfahren eines zweiten Betriebspunkts mit der Serien-Verbrennungskraftmaschine und Erfassen (z. B. Messen) eines zweiten Drucksignals bei einer (angenommenen) zweiten Einlassnockenwellen-Phasenlage und einer (angenommenen) zweiten Auslassnockenwellen-Phasenlage und Bestimmen eines zweiten Merkmals (insbesondere ein gleiches Merkmal wie das erste Merkmal oder ein anderes Merkmals als das erste Merkmal) aus dem zweiten Drucksignal;
5. e) Bestimmen der zweiten Punktewolke gemäß Schritt II., wobei die einzelnen zweiten Punkte der zweiten Punktewolke durch die aus den Modellen abgeleiteten Kombinationen der Ist-Einlassnockenwellen-Phasenlage und der Ist-Auslassnockenwellen-Phasenlage für das in Schritt d) bestimmte zweite Merkmal gebildet werden;
6. f) Bilden einer Schnittmenge der ersten Punktewolke und der zweiten Punktewolke; wobei ein aus der Schnittmenge bestimmter Schnittpunkt der Punktewolken die Ist-Einlassnockenwellen-Phasenlage und die Ist-Auslassnockenwellen-Phasenlage darstellt.

The method comprises at least the following steps:

1. a) Determination of models on a reference internal combustion engine for different operating points, with each model for each operating point of the reference internal combustion engine having a relationship between a pressure signal determined on the reference internal combustion engine (or at least one feature of a pressure signal) as a function of the actual Represents the intake camshaft phase position and the actual exhaust camshaft phase position of the respective operating point;
2. b) Approaching a first operating point with the series internal combustion engine and detecting (e.g. measuring) a first pressure signal at an (assumed) first intake camshaft phase position and an (assumed) first exhaust camshaft phase position and determining a first feature from the first pressure signal ;
3. c) Determination of the first point cloud according to step I., the individual first points of the first point cloud by the combinations derived from the models of the actual intake camshaft phase position and the actual Exhaust camshaft phase position for the first feature determined in step b) are formed;
4. d) Determining a second feature (in particular a feature other than the first feature) from the first pressure signal or approaching a second operating point with the series internal combustion engine and detecting (e.g. measuring) a second pressure signal in the case of an (assumed) second intake camshaft Phase position and an (assumed) second exhaust camshaft phase position and determining a second feature (in particular a feature identical to the first feature or a feature different from the first feature) from the second pressure signal;
5. e) Determining the second point cloud according to step II., the individual second points of the second point cloud being formed by the combinations derived from the models of the actual intake camshaft phase position and the actual exhaust camshaft phase position for the second feature determined in step d) ;
6. f) forming an intersection of the first point cloud and the second point cloud; wherein an intersection of the point clouds determined from the intersection represents the actual intake camshaft phase position and the actual exhaust camshaft phase position.

The above, in particular non-exhaustive, classification of the process steps into a) to f) is primarily intended to serve only to differentiate and not to enforce a sequence and / or dependency. The frequency of the process steps z. B. during setup and / or operation of the system may vary. It is also possible that process steps overlap one another at least partially in time. Process steps b) and c) and d) and e) each take place simultaneously with very particular preference. In particular, step f) takes place after steps b) to e), possibly at least temporally overlapping with steps d) and e). In particular, steps b) to f) are carried out after step a) and in the order listed.

In particular, steps III. and IV. carried out as part of step f). Step III. can also be carried out independently of step f).

The rotational position of a crankshaft of an internal combustion engine determines the position of a piston in a cylinder of the internal combustion engine and, if there are several cylinders, in particular the position of the pistons in relation to one another. To improve the emissions and / or the generated power of the internal combustion engine, the phase positions of each individual camshaft and thus the control times of the valves (inlet valve, outlet valve) can be adjusted individually. The control times of the valves can be changed during operation of the internal combustion engine by adjusting the phase position of the relevant camshaft, but only jointly for all valves actuated by the respective camshaft. In this way, a desired combination of phase positions of the camshafts and thus specific control times of the valves can be set for each operating point of the internal combustion engine. In an operating point that z. B. is defined by a speed of the crankshaft, an applied torque and a phase position of the camshafts, so there is a fixed combination of the phase positions of the camshafts during the rotational movement of the crankshaft.

The proposed method is intended, in particular, to enable a control of the camshafts to be checked and, if necessary, changed or corrected during operation.

In particular, certain combinations of camshaft phase positions are specified by a control unit for certain operating points of the internal combustion engine. The phase position of each camshaft is determined as a function of a rotational position of the crankshaft. For example, due to a change in components, it can happen that a camshaft phase position specified (assumed) by the control unit is not actually implemented, but that at least one camshaft adopts a different actual phase position that deviates from a specified target phase position. The proposed method is intended to enable this actual phase position of the camshafts that is actually present to be recognized and compared with the control variables specified by the control unit. A correction can be made in the control unit from the comparison, so that from this point in time the control variables specified by the control unit can set a desired and reproducible phase position of the camshafts.

In particular, the method assumes that the errors in the camshaft phase positions are determined by components and tolerances (e.g. installation errors in the sensor, encoder wheel, etc.) and thus the relative adjustment of the camshaft phase positions from one operating point to the other the same quality or accuracy can be set and recorded as the repeated approach to an operating point with a certain combination of camshaft phase positions.

The method thus makes it possible, in particular, that a freely selectable number of operating points can be approached, solely via the number of those that differ from one another Operating points the robustness and stability of the result, i.e. the determination of the actual camshaft phase positions, can be influenced. Furthermore, certain combinations of operating points can be selected, which enable the most robust possible determination of the actual phase positions of the camshafts. However, the method can also include the determination of a plurality of features from a pressure signal that was ascertained or measured at the same operating point, the point clouds then differing only with regard to the respective feature.

To determine the actual phase position of the camshafts, models are determined on a reference internal combustion engine in accordance with step a). These models are used in steps c) and e) to determine the point clouds.

In these models, the actual phase positions of the camshafts and the pressure signal or the at least one characteristic of the pressure signal are stored for the respective operating point. These models are stored in a control unit during operation of the series internal combustion engine and recognized as valid. In this case, for an operating point of the reference internal combustion engine, e.g. B. defined by the speed of the crankshaft and an applied torque as well as by a target phase position of the camshaft, different combinations of the actual phase positions of the camshafts and the respectively determined characteristic of the pressure signal detected. When the series internal combustion engine is in operation, the operating points for which models are stored are approached in order to carry out the method.

The actual phase positions and features can be measured on the reference internal combustion engine by sensors, e.g. B. by pressure sensors, rotation angle sensors, etc., can be determined, the reference internal combustion engine is characterized by particularly small deviations and particularly well-known components.

It is therefore assumed in the reference internal combustion engine that the target phase position corresponds to the actual phase position.

In particular, a model is generated for each operating point and stored in the control unit. The model describes the relationship between the actual phase positions and the pressure signal or the at least one characteristic of the pressure signal.

Each model can have a plurality of characteristic diagrams or sub-models. A first map or sub-model of a model includes, for. B. on the basis of certain values of the actual intake camshaft phase position and, depending on this, set values of the actual exhaust camshaft phase position, the feature determined for the respective combination.

A second map or sub-model of a model includes, for. B. on the basis of certain values of the actual intake camshaft phase position and the values of the characteristic of the pressure signal present in each case, the actual exhaust camshaft phase position present in this combination and at this operating point.

A third map or sub-model of a model includes, for. B. on the basis of certain values of the actual exhaust camshaft phase position and the values of the characteristic of the pressure signal present in each case, the actual intake camshaft phase position present in this combination and at this operating point.

The second and third map can, for. B. each be determined by inverting the first map.

Each characteristic diagram or sub-model describes the respective third variable on the basis of specific values of two input variables. Starting from the first map, z. B. a second map (sub-model) can be formed by inverting the first map. On the basis of certain values of the actual intake camshaft phase position, the second characteristic diagram then comprises the characteristics determined as a function of this and the values of the actual exhaust camshaft phase position set for the respective combination. A third map (sub-model) can also be formed by inverting the first map. On the basis of certain values of the actual exhaust camshaft phase position, the third characteristic field then comprises the characteristics determined as a function thereof and the values of the actual intake camshaft phase position set for the respective combination.

Saving the large number of characteristic diagrams (sub-models) can in particular reduce the computational effort required to carry out the method during operation of the series internal combustion engine, since reading out the relevant values of the phase positions for features determined during operation can be simplified.

In particular, any values for actual phase positions and features are later determined by interpolation with the aid of the characteristic diagrams or sub-models.

In particular, the characteristic diagrams can also be implemented or replaced by systems of equations.

During operation of the series internal combustion engine, the features of the pressure signals are recorded and evaluated in the operating points according to steps b) and d). The phase position of the camshafts present at the respective operating point (but possibly incorrect because it has been adjusted) is also recorded. These recorded phase positions are used in particular in step f) to determine the deviation of the phase positions set in steps b) and d) (but not actually present) from the actually present actual phase positions, so that in the subsequent operation of the series internal combustion engine If necessary, values corrected for this deviation can be used for the phase position.

The operating points reached during operation of the series internal combustion engine correspond in particular to the operating points for which the models are stored in the control unit.

In particular, the pressure signals detected in steps b) and d) or the at least one feature in steps c) and e) are compared with the models.

The combinations of the actual phase positions of the camshafts that are possible for this operating point and the detected feature are then read from the models in accordance with steps c) and e). For the point cloud z. B. determined for which actual values of the intake camshaft phase position this feature and thus which actual exhaust camshaft phase position is present. Next is for the same point cloud z. B. determined for which values of the actual exhaust camshaft phase position this feature and thus which actual intake camshaft phase position is present. The point cloud determined in this way can, for. B. be simulated by a function. The function can e.g. B. form a line in a diagram. In the diagram, e.g. B. the actual intake camshaft phase position can be plotted on a first axis and the actual exhaust camshaft phase position on a second axis. Since each point of the point cloud has the coordinates of the respective combination of actual phase positions for this one feature, the point cloud in the present case only has two dimensions. The diagram shows the actual phase position combinations in which the measured feature results in the model or sub-model - i.e. a contour line in the model.

The point clouds are composed in particular of points that can be read out from the characteristic diagrams or sub-models. For example, the point cloud determined for one operating point is composed of the actual intake camshaft phase positions for the detected feature and the actual exhaust camshaft phase positions for this actual intake camshaft phase position and this operating point. The actual exhaust camshaft phase position is therefore read out in particular from the corresponding characteristic map or sub-model that is already stored in the control unit or is available during operation of the series internal combustion engine. The point cloud is also composed of the actual exhaust camshaft phase positions for the detected feature and the actual intake camshaft phase positions for this actual exhaust camshaft phase position and this operating point.

The point cloud determined for one operating point is composed in particular of the points derived from the second characteristic diagram described above and from the points derived from the third characteristic diagram described above. The corresponding values of the actual intake camshaft phase position and the values of the actual exhaust camshaft phase position available for this combination can be read out from the second characteristic field for the measured feature. The combinations of these values form the individual points of the point cloud derived from the second characteristic diagram. The corresponding values of the actual exhaust camshaft phase position and the values of the actual intake camshaft phase position available for this combination can be read out from the third characteristic field for the measured feature. The combinations of these values form the individual points of the point cloud derived from the third characteristic diagram.

A plausibility check can already be carried out with the model or the sub-models. It can e.g. B. it can be checked whether a clear behavior of the points forming the respective point cloud can be expected for the selected operating points, at least in a partial area of the point clouds comprising the assumed or expected camshaft phase positions. If not, only permissible areas of the point cloud can be selected or a different operating point is approached or the operating point is approached repeatedly or the pressure signal is recorded again.

For example, the points determined from one sub-model can result in a circle in a diagram. However, if the points determined from the other sub-model include this circle, e.g. If, for example, you add the first point cloud in only one quadrant of the circle, this quadrant and the points it contains can be used sensibly as a point cloud.

In particular, in at least one of steps b) and d) at least one further feature is detected from the respective pressure signal, and in step a) for this further feature as well Models have been created, which will be used in steps c) and e). The further feature can e.g. B. be the signal of another pressure sensor. This can e.g. B. be arranged in the intake tract or in the outlet tract. The further feature can also comprise another feature of the same pressure signal, e.g. B. an amplitude, a maximum value, etc ..

In particular, steps d) to f) are carried out for at least one third operating point.

In particular, at least one of the operating points approached in steps b) and d) is selected as a function of a suitability determined on the reference internal combustion engine, the suitability having the greatest possible intersection angle of the intersection angle determined in steps c) and e) and in step f) includes point clouds brought to intersect.

In particular, from the detected pressure signals with a Fourier transformation, e.g. B. a discrete Fourier transform, the amplitudes of certain signal frequencies of the pressure signal are determined as features. Such a method for determining the amplitudes of certain signal frequencies is z. B. from the aforementioned DE 10 2016 219 582 B3 known.

However, other methods for determining features from the pressure signal can also be used. The present method is not limited to performing a Fourier transform. In addition to the amplitude, other characteristics of the pressure signal can also be used.

In particular, the operating points approached in steps b) and d) each have either the same assumed phase positions and different features (that is, different characteristics of the pressure signals are recorded) or different phase positions and the same features, with different phase positions for forming the intersection according to step f) at least one point cloud is shifted by the value of a deviation present between the different phase positions (that is to say by the adjustment of the camshaft position causing the different phase positions).

In steps b) and d), in particular, mutually different operating points of the series internal combustion engine are approached. Step d) can, however, be carried out for the same operating point. A pressure signal or at least one feature of the pressure signal and the (assumed) phase positions are determined in each case. When approaching different operating points at which the same feature is detected but which have different phase positions, the deviation of the phase positions between the different operating points can be determined. This deviation is therefore the difference between the phase positions, i.e. H. the difference between the phase position of the respective camshaft in the first and in the second operating point. In particular, it is assumed that the same boundary conditions apply to the phase positions set on the series internal combustion engine. B. mounting errors, encoder wheel, sensor, etc., and that the relative adjustment between the phase positions can be set and recorded with high quality. It is therefore assumed that a difference between the phase positions set in the different operating points (possibly not actually present) corresponds to the difference that is present between the actual phase positions that are actually present.

The difference between the first phase positions and the second phase positions is determined in step d), e) and / or in particular immediately before step f).

In step f), using the difference and knowing the models, a point cloud or the function or the line in the diagram can be corrected so that point clouds corresponding to one another can be obtained and used to form the intersection.

In particular, the pressure signals in the series internal combustion engine are detected at least in an intake side or in an outlet side of the series internal combustion engine via a pressure sensor arranged there. The respective at least one characteristic of the pressure signal can be determined from the detected pressure signals, e.g. B. ungskraftmaschi ne in a control unit of the series internal combustion.

In particular, the actual phase positions determined in step f) are used in a control unit of the series internal combustion engine to correct control variables provided by the control unit for operating the series internal combustion engine. In particular, the control variables used so far are changed so that in further operation, for. B. changed phase positions can be set.

The at least one point of intersection of the point clouds determined in step f) or IV. Thus in particular forms the combination of actual phase positions, i.e. the actual intake camshaft phase position and the actual exhaust camshaft phase position that are actually present in the operating points.

These values of the actual phase positions can now be used to recalibrate the values used up to this current point in time for the assumed phase positions (that is, for example, the first phase positions and the second phase positions). A deviation of the actual phase position of the relevant camshaft from the phase position set up to that point is determined and, based on this deviation, the control variable is changed in the control unit. Thereafter, the (set) phase position set on the series internal combustion engine, ie z. B. correspond to the first and second phase position of the actually present respective actual phase position.

The control variable can, for. B. be the phase position of a camshaft. The method can be used to detect deviations between the actual phase position actually present and a (setpoint) phase position set and assumed on the series internal combustion engine, and the phase position of the camshaft can be corrected or calibrated. The newly set phase positions should then in particular correspond to the actual phase positions. This state can in particular also be checked and checked for plausibility using the present method.

In particular, the control variables provided by the control device for operating the series internal combustion engine are only changed, taking into account the actual phase positions, if a minimum deviation is determined between the actual phase positions and the control variables comparable to them. Correction may not be necessary because the determined deviation of the actual phase position lies within a predeterminable tolerance.

In particular, the minimum deviation varies as a function of at least one of the following parameters: speed, crankshaft position, ambient pressure, VTG position, throttle valve position, composition of the fuel-air mixture. In particular, the minimum deviation can therefore have a different value depending on the operating point or parameter, so that a decision can be made as a function of at least one of the parameters mentioned as to whether the control variables are to be corrected.

In particular, the value becomes every first point of the first point cloud and every second point of the second point cloud 1 assigned and assigned the value zero to all other positions apart from the points.

When adding the point clouds, the values of the individual positions that correspond to one another are added. If there are two points at a position (a first point and a second point), the value for this position is obtained 2 . If there is only one point at a position (a first point or a second point), the value results for this position 1 . If there is no point at a position (i.e. neither a first point nor a second point), the value 0 results for this position.

If a threshold value is set to a value of at least 2, only positions are identified at which there is both a first point and a second point, i.e. an intersection of the point clouds.

In particular, for at least one axis of the coordinate system under consideration, ie z. B. for an x-axis or a y-axis etc., a grid can be defined. The grid can e.g. B. with the value zero, e.g. B. the color black, be pre-assigned. The grid can e.g. B. correspond to the pixels or image points of a black-and-white image. In particular, a user can define the number of pixels or the resolution of the grid. In this way, a desired resolution or accuracy of the method and, depending on this, a computing speed can be defined. In particular, a set of points arranged adjacent to one another can be determined for a point cloud and the pixel (s) corresponding thereto, e.g. B. with the value 1 , possibly represented by the color white. The grid is thus quantified and forms the point clouds in the form of z. B. a black and white image.

In particular, in step IV. The addition of the first point cloud and the second point cloud and the determination of an intersection or an intersection point of the point clouds, the point of intersection being at a position which is a threshold value of at least 2. The actual phase positions of the camshafts result from the intersection.

The pixels of the grid that are then e.g. B. with the value 2 are occupied can be covered with another color.

In particular, a large number of point clouds can be represented in the coordinate system or in a plane (with two dimensions) and further intersection points can be determined.

The grid used can e.g. B. processed with an image processing algorithm. It can, for. B. contiguous points can be classified and collected as objects with a certain spread. Each of these objects can e.g. B. represent a pixel cloud (or one or more pixel islands) or a plurality of contiguous, that is to say adjacent pixels, and can then be characterized or described with a center or an area. Prefers all points of an object each form an intersection point of the point clouds under consideration, in which case a mean value of the pixel coordinates (e.g. a geometric center of gravity of the object or of the at least one island) can then be formed from the object. The mean value can then be viewed as the best approximation to the single point of intersection sought (that is, for example, the sought combination of actual phase positions of the camshafts).

In particular, a resolution of a grid of the coordinate system can be changed at least for the addition according to step IV, so that points of point clouds can optionally be resolved more precisely or less precisely. At a lower resolution z. B. Points of different point clouds, which are arranged at different positions in the coordinate system but are positioned closest to one another, are combined to form a point of intersection.

In particular, in step IV. The points of intersection that result from the superposition of more than two points from different point clouds can be replaced by other threshold values that are greater than " 2 “Are to be identified. As a result, the robustness of the method can be further increased because, for. B. several operating points can be approached and the phase positions of the camshafts can be checked. The higher the threshold value and the higher the number of point clouds determined (independently of one another) and used to form an intersection, the more precisely the actual camshaft phase position can be determined.

In particular, in step IV. The threshold value can be specified as a function of the expected number of point clouds forming the intersection or point of intersection.

With the method, the intersections of any number of point clouds can be evaluated without the respective point cloud having to meet a condition with regard to continuity, uniqueness, differentiability, etc.

The method can in particular be carried out in multi-dimensional coordinate systems, that is to say in particular with more than the previously described two-dimensional coordinate systems in which the point clouds for determining the camshaft phase positions can be represented.

In particular, at least step III. or step IV. applied to only a partial area of at least one point cloud. In particular, certain partial areas of individual point clouds can be excluded in which z. B. intersections of the point clouds considered may be viewed as implausible. In particular, these sub-areas can be determined by mathematical methods, e.g. B. by inversion according to a size, so z. B. for a coordinate of the relevant coordinate system.

It is also proposed an internal combustion engine, at least comprising a crankshaft, an adjustable intake camshaft and / or an adjustable exhaust camshaft, at least one piston connected to the crankshaft and a cylinder in which the piston performs stroke movements, and an intake side, via which at least air via at least an inlet valve that can be actuated by the inlet camshaft can be fed to the cylinder, and an outlet side via which exhaust gas can be discharged from the cylinder via at least one outlet valve that can be actuated by the exhaust camshaft. At least one pressure sensor for detecting pressure signals is arranged in the intake side and / or in the outlet side. The internal combustion engine further comprises a control device which is suitably designed, or equipped, configured or programmed to carry out the described method.

In particular, a control device is also proposed that is equipped, configured or programmed to carry out the described method.

Furthermore, the method can also be carried out by a computer or with a processor of a control unit.

Accordingly, a system for data processing is also proposed which comprises a processor which is adapted / configured in such a way that it carries out the method or part of the steps of the proposed method.

A computer-readable storage medium can be provided which comprises instructions which, when executed by a computer / processor, cause the latter to execute the method or at least some of the steps of the proposed method.

The statements relating to the method can in particular be transferred to the internal combustion engine and / or the computer-implemented method (that is to say the computer or the processor, the data processing system, the computer-readable storage medium) and vice versa.

The use of indefinite articles (“a”, “an”, “an” and “an”), especially in the patent claims and the description reproducing them, is to be understood as such and not as a numerical word. Terms or components introduced with it are therefore to be understood in such a way that these are present at least once and, in particular, can also be present several times.

As a precaution, it should be noted that the numerals used here (“first”, “second”, ...) primarily (only) serve to differentiate between several similar objects, sizes or processes, so in particular no dependency and / or sequence of these objects, sizes or prescribe processes to each other. Should a dependency and / or sequence be required, this is explicitly stated here or it is obvious to the person skilled in the art when studying the specifically described embodiment. If a component can occur several times (“at least one”), the description of one of these components can apply equally to all or part of the majority of these components, but this is not mandatory.

• 1: eine Serien-Verbrennungskraftmaschine in einer Seitenansicht im Schnitt;
• 2: ein erstes dreidimensionales Diagramm;
• 3: ein zweites dreidimensionales Diagramm;
• 4: ein erstes zweidimensionales Diagramm; und
• 5: ein zweites zweidimensionales Diagramm.

The invention and the technical environment are explained in more detail below with reference to the accompanying figures. It should be pointed out that the invention is not intended to be restricted by the exemplary embodiments cited. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and to combine them with other components and findings from the present description. In particular, it should be pointed out that the figures and in particular the size relationships shown are only schematic. Show it:

• 1 : a series internal combustion engine in a side view in section;
• 2 : a first three-dimensional diagram;
• 3 : a second three-dimensional diagram;
• 4th : a first two-dimensional diagram; and
• 5 : a second two-dimensional diagram.

1 shows a series internal combustion engine 5 in a side view in section. The series internal combustion engine 5 includes a crankshaft 31 , an adjustable intake camshaft 2 and an adjustable exhaust camshaft 4th , at least one with the crankshaft 31 connected piston 32 and a cylinder 33 in which the piston 32 Performs lifting movements, as well as a suction side 26th , over the at least air over at least one of the intake camshaft 2 actuatable inlet valve 34 the cylinder 33 is feedable, and an outlet side 27 , via the exhaust gas via at least one of the exhaust camshaft 4th actuatable outlet valve 35 out of the cylinder 33 is deductible. In the suction side 26th and in the outlet side 27 is a pressure sensor each 28 for the acquisition of pressure signals 11 , 12th , 13th arranged (at least one pressure sensor is required for the procedure 28 required). The series internal combustion engine 5 further comprises a control device 29 , which is suitably designed or equipped, configured or programmed to carry out the described method.

The method is used to determine a combination of an actual intake camshaft phase position 1 an intake camshaft 2 and an actual exhaust camshaft phasing 3 an exhaust camshaft 4th a series internal combustion engine 5 . The method is used in the operation of the series internal combustion engine 5 carried out. The respective actual phase position 1 , 3 the camshafts 2 , 4th is in relation to an operating point 6th , 7th , 8th the series internal combustion engine 5 certainly.

In the process, for. B. according to step a) a determination of models 9 , 10 (please refer 2 and 3 ) on a reference internal combustion engine for different operating points 6th , 7th , 8th , with each model 9 , 10 for one operating point each 6th , 7th , 8th the reference internal combustion engine a relationship between a pressure signal determined on the reference internal combustion engine 11 , 12th 13th (or at least one feature 16 , 21 of a pressure signal 11 , 12th , 13th ) as a function of the actual intake camshaft phase position 1 and the actual exhaust camshaft phasing 3 of the respective operating point 6th , 7th , 8th represents.

According to step b), a first operating point is approached 6th with the series internal combustion engine 5 and detecting (e.g. measuring) a first pressure signal 11 with an (assumed) first intake camshaft phase position 14th and an (assumed) first exhaust camshaft phase position 15th and determining a first feature 16 from the first pressure signal 11 .

According to step c), a first point cloud is determined 17th , (see e.g. 4th and 5 ), the individual points 18th the first point cloud 17th through the out of the models 9 , 10 derived combinations of the actual intake camshaft phase position 1 and the actual exhaust camshaft phasing 3 for the first feature determined in step b) 16 can be formed (as a union).

According to step d), a second feature is determined 21 from the first pressure signal 11 or approaching a second operating point 7th with the series internal combustion engine 5 and detecting (e.g. measuring) a second pressure signal 12th with an (assumed) second intake camshaft phase position 19th and an (assumed) second exhaust camshaft phase position 20th and determining a second feature 21 from the second pressure signal 12th .

According to step e), a second point cloud is determined 22nd (see e.g. 4th and 5 ), the individual points 36 the second point cloud 22nd through the out of the models 9 , 10 derived combinations of the actual intake camshaft phase position 1 and the actual exhaust camshaft phasing 3 for the second feature determined in step d) 21 (of the first operating point 6th or the second operating point 7th ) are formed.

According to step f), an intersection of the first point cloud is formed 17th and the second point cloud 22nd (see e.g. 4th and 5 ), where one from the intersection 41 certain intersection 23 the point clouds 17th , 22nd the actual intake camshaft phasing 1 and the actual exhaust camshaft phasing 3 represents.

The rotational position of a crankshaft 31 an internal combustion engine determines the position of a piston 32 in a cylinder 33 the internal combustion engine and, if there are several cylinders 33 , especially the location of the pistons 32 to each other. To improve emissions and / or the power generated by the internal combustion engine 5 can change the phase positions 1 , 3 every single camshaft 2 , 4th and thus the control times of the valves (inlet valve 34 , Exhaust valve 35 ) can be adjusted individually. Here are the control times of the valves 34 , 35 during operation of the internal combustion engine 5 by adjusting the phase position 1 , 3 of the camshaft in question 2 , 4th changeable, but for all of the respective camshaft 2 , 4th operated valves 34 , 35 only together. This means that for every operating point 6th , 7th , 8th the internal combustion engine 5 a desired combination of phase positions 1 , 3 the camshafts 2 , 4th and thus certain valve timing 34 , 35 can be set. In one operating point 6th , 7th , 8th , the z. B. by a speed of the crankshaft 31 , an applied torque and a phase position 1 , 3 the camshafts 2 , 4th is defined, so lies during the rotational movement of the crankshaft 31 a fixed combination of the phase positions 1 , 3 the camshafts 2 , 4th in front. Through a control unit 29 are for certain operating points 6th , 7th , 8th the internal combustion engine 5 certain combinations of camshaft phasing 1 , 3 as control variables 30th given.

The proposed method is intended in particular to enable the camshafts to be regulated during operation 2 , 4th checked and, if necessary, changed or corrected.

For example, due to a change in components, one of the control unit 29 specified (assumed) camshaft phase position 14th , 15th , 19th , 20th but not actually realized, but that at least one camshaft 2 , 4th a different actual phase 1 , 3 assumes that deviates from a predetermined target phase position. The proposed method is intended to enable this actual phase position that is actually present 1 , 3 the camshafts 2 , 4th is recognized and with the control unit 29 specified control parameters 30th is matched. From the comparison, the control unit 29 a correction can be made so that from this point in time the control unit 29 specified control parameters 30th a desired and reproducible phase position 1 , 3 the camshafts 2 , 4th can adjust.

2 shows a first three-dimensional diagram. 3 shows a second three-dimensional diagram. The diagrams are described together below.

The respective result or the value of the characteristic is on the vertical axis of the diagrams 16 , 21 of a pressure signal 11 , 12th applied. The actual intake camshaft phase position is on one horizontal axis 1 and the actual exhaust camshaft phase position on the other horizontal axis 3 applied. For recording the actual phase position 1 , 3 the camshafts 2 , 4th are models according to step a) of the procedure 9 , 10 determined on a reference internal combustion engine. These models 9 , 10 are used in steps c) and e) to determine the point clouds 17th , 22nd .

In these models 9 , 10 are for the respective operating point 6th , 7th , 8th the actual phases 1 , 3 the camshafts 2 , 4th and the pressure signal 11 , 12th , 13th or the at least one feature 16 , 21 of the pressure signal 11 , 12th , 13th saved. These models 9 , 10 are in operation of the series internal combustion engine 5 in a control unit 29 deposited and recognized as valid. Thereby are for an operating point 6th , 7th , 8th the reference internal combustion engine, e.g. B. defined by the speed of the crankshaft 31 and an applied torque and a target phase position of the camshaft 2 , 4th , different combinations of the actual phase positions 1 , 3 the camshafts 2 , 4th and the characteristic determined in each case 16 , 21 of the pressure signal 11 , 12th , 13th detected. During operation of the series internal combustion engine 5 the operating points are used to carry out the process 6th , 7th , 8th approached, for the models 9 , 10 are deposited.

In the reference internal combustion engine, it is assumed that the target phase position is the actual phase position 1 , 3 corresponds to.

For one operating point each 6th , 7th , 8th becomes one model at a time 9 , 10 generated and in the control unit 29 deposited. The model 9 , 10 describes the relationship between the actual phases 1 , 3 and the pressure signal 11 , 12th , 13th or the at least one feature 16 , 21 of the pressure signal 11 , 12th , 13th .

The first diagram forms a in or for a first operating point 6th certain first model 9 from. The first model 9 includes a plurality of first point clouds 17th . The first coordinate 37 every first point 18th the accumulation of the first point clouds 17th is the actual input wave phasing 1 . The second coordinate 38 every first point 18th is the output wave phasing 3 and the third coordinate 39 the first feature 16 of the first pressure signal 11 .

The second diagram forms one for a second operating point 7th certain second model 10 from. The second model 10 comprises a plurality of second point clouds 22nd . The first coordinate 37 every other point 36 the accumulation of second point clouds 22nd is the actual input wave phasing 1 . The second coordinate 38 every other point 36 is the actual output wave phasing 3 and the third coordinate 39 the second feature 21 of the second pressure signal 12th .

4th shows a first two-dimensional diagram. 5 shows a second two-dimensional diagram. The 4th and 5 are described together below. On the remarks too 1 to 3 is referred.

The actual exhaust camshaft phase position is on the vertical axis 3 as the second coordinate 38 applied. The actual intake camshaft phase position is on the horizontal axis 1 as the first coordinate 37 applied. In the respective diagram of the 4th and 5 are the point clouds 17th , 22nd , 44 shown, from the respective, in the 2 and 3 shown model 9 , 10 , for that on the series internal combustion engine 5 measured or specific feature 16 , 21 , could be determined. Because every point 18th , 36 the respective point cloud 17th , 22nd , 44 the coordinates 37 , 38 , 39 the respective combination of actual phases 1 , 3 for the characteristic in question 16 , 21 shows the point clouds 17th , 22nd , 44 present only two dimensions. The diagrams or the point clouds 17th , 22nd , 44 represent the actual phase position combinations 1 , 3 which are in the model 9 , 10 the measured feature 16 , 21 thus results in a contour line in the model 9 , 10 . The second diagram 5 shows a section of the first diagram.

The pressure signals detected in steps b) and d) 11 , 12th , 13th or the at least one feature 16 , 21 are in steps c) and e) with the models 9 , 10 compared. From the models 9 , 10 are then according to steps c) and e) for this operating point 6th , 7th , 8th and the detected feature 16 , 21 possible combinations of the actual phase positions 1 , 3 the camshafts 2 , 4th read out. For the point cloud 17th , 22nd , 44 is z. B. determined for which actual values of the intake camshaft phase position 1 this feature 16 , 21 and thus which actual exhaust camshaft phase position 3 is present. Next is for the same point cloud 17th , 22nd , 44 z. B. determined for which values the actual exhaust camshaft phase position 3 this feature 16 , 21 and thus which actual intake camshaft phase position 1 is present. The point cloud determined in this way 17th , 22nd , 44 can e.g. B. be simulated by a function. The function can e.g. B. form a line in a diagram (see 4th and 5 ). The point clouds 17th , 22nd , 44 but do not have to be writable by a function.

The method is based on determining an intersection point 23 of at least two point clouds 17th , 22nd , 44 directed. According to step I. a first point cloud is determined 17th with a plurality of first points 18th . According to step II. A second point cloud is determined 22nd with a plurality of second points 36 . Every point 18th , 36 is by a plurality of coordinates 37 , 38 , 39 defines and thus has a defined position in a multi-dimensional coordinate system 40 (please refer 2 to 5 ) on. According to step III. a value is assigned " 1 “For every point 18th , 36 every point cloud 17th , 22nd , 44 and assigning a value "zero" for every other position in the coordinate system 40 (please refer 4th and 5 ). According to step IV. The first point cloud is added 17th and the second point cloud 22nd (as well as the third point cloud 44 ) and finding an intersection 41 the point clouds 17th , 22nd , 44 being the intersection 41 through at least one intersection 23 is formed in the coordinate system 40 is arranged at a position that has a threshold value of at least " 2 “(With three point clouds 17th , 22nd , 44 possibly "three").

The intersection 23 Two curves or functions are usually determined by forming the values of both curves at common interpolation points in a main direction (e.g. x-direction). The difference between the two values results in a curve, the zeros of which are the points of intersection 23 represent both curves. For this purpose, both curves in the main direction must have a unique result. If one of the curves in the main direction is not strictly monotonous and unambiguous, there would be more than one corresponding y-value or second coordinate 38 (see e.g. first point cloud 17th in 4th and 5 ) for an x value or first coordinate 37 . This means that intersections cannot be made for all sections of the curves 23 be determined.

The procedure described here also enables data records that cannot be described by curves or functions (point clouds 17th , 22nd , 44 ) an intersection 41 (i.e. one or more intersections 23 ) to determine these data sets.

The data sets considered here (point clouds 17th , 22nd , 44 ) show z. B. partially discontinuous, line-forming points 18th , 36 (which can be described by a function or a curve). The data sets considered here are made up of at least partially individually determined pairs of values (with three coordinates 37 , 38 , 39 ), i.e. points 18th , 36 together that as a point cloud 17th , 22nd , 44 depict the context under consideration. The points 18th , 36 every point cloud 17th , 22nd , 44 therefore do not necessarily have to be arranged adjacent to one another, but can also be distributed in islands or areas. Also can for a coordinate 37 , 38 , 39 several points 18th , 36 with different other coordinates 39 , 38 , 37 in the point cloud 17th , 22nd , 44 be present and vice versa. The process forms points of intersection 23 these point clouds 17th , 22nd , 44 . The point clouds 17th , 22nd , 44 also multiple intersections 23 that form the intersection 41 form.

With an addition of the point clouds 17th , 22nd , 44 the values of the individual corresponding positions are added. There are two points in one position 18th , 36 (a first point 18th and a second point 36 ) the value for this position is " 2 ". There is only one point at a position 18th , 36 before (a first point 18th or a second point 36 ) the value for this position is " 1 ". If there is no point at a position 18th , 36 before (i.e. neither a first point 18th a second point 36 ) results in the value "zero" for this position. If a threshold value is set to the value of at least " 2 “, Only positions are identified that have both a first point 18th as well as a second point 36 exists, i.e. an intersection 23 of two of the point clouds 17th , 22nd , 44 .

It can be used for at least one axis of the coordinate system under consideration 40 , so z. B. for the first coordinate 37 or the second coordinate 38 , a grid 42 To be defined. The grid 42 can e.g. B. with the value "zero", z. B. the color black, be pre-assigned. The grid 42 can e.g. B. correspond to the pixels or image points of a black-and-white image. In particular, a user can determine the number of pixels or the resolution of the grid 42 (see difference between 4th and 5 ) define. In this way, a desired resolution or accuracy of the method and, depending on this, a computing speed can be defined. In particular, for a point cloud 17th , 22nd , 44 a set of adjacent points 18th , 36 are determined and the pixel or pixels corresponding thereto z. B. with the value " 1 ", Which can be represented by the color white, if necessary. The grid 42 is thus quantified and forms the point clouds 17th , 22nd , 44 in the form of B. a black and white image.

The first point cloud is added in step IV 17th and the second point cloud 22nd (and also adding the third point cloud 44 ) and finding an intersection 41 or an intersection 23 the point clouds 17th , 22nd , 44 , where the intersection 23 is at a position that has a threshold value of at least " 2 "Is. From the intersection 23 the actual phase positions result 1 , 3 the camshafts 2 , 4th .

When adding three point clouds 17th , 22nd , 44 the threshold value can be at least "three". In 4th becomes the intersection 23 from the intersection 41 of the three point clouds 17th , 22nd , 44 educated.

The pixels of the grid 42 that for the intersection 23 then z. B. with the value " 2 "Or" three "are occupied, can be occupied with (each) another color.

In particular, a large number of point clouds can also be created in this way 17th , 22nd , 44 in the coordinate system 40 or in one plane (for two dimensions, see 4th and 5 ) and further intersections 23 (please refer 5 ) or different intersections 23 , (i.e. intersections 23 , in which there are two, three or more point clouds 17th , 22nd , 44 cut) can be determined.

The grid used 42 can e.g. B. processed with an image processing algorithm. It can, for. B. related points 18th , 36 classified and collected as objects with a certain spread. Each of these objects can e.g. B. represent a pixel cloud or a plurality of contiguous, that is to say adjacent pixels, and can then be characterized or described with a center or an area. Preferably all points form 18th , 36 of an object each have an intersection point 23 of the point clouds considered 17th , 22nd , 44 , whereby a mean value of the pixel coordinates can then be formed from the object. The mean value can then be used as the best approximation to the single point of intersection sought 23 (e.g. the desired combination of actual phase positions 1 , 3 the camshafts 2 , 4th ) be considered.

At least one of the operating points approached in steps b) and d) 6th , 7th , 8th can be selected as a function of a suitability ascertained on the reference internal combustion engine, the suitability having an intersection angle that is as large as possible 24 that determined in steps c) and e) and point clouds made to intersect in step f) 17th , 22nd , 44 includes.

In 5 is z. B. shown that the first point cloud 17th and the second point cloud 22nd as well as the first point cloud 17th and the third point cloud 44 intersect and each intersection 23 form. These intersections 23 can through a coarser grid 42 as a single intersection 23 can be represented (see 4th ) or can be described by an object with a certain extent or here an area. The individual intersection point determined from this 23 (please refer 4th ) can then be determined as the best approximation to the center of this area.

At least for the addition according to step IV. A resolution of a raster can therefore 42 of the coordinate system 40 can be changed so that points 18th , 36 of point clouds 17th , 22nd , 44 possibly more precisely ( 5 ) or less accurate ( 4th ) can be resolved. At a lower resolution z. B. Points 18th , 36 different point clouds 17th , 22nd , 44 that are at different positions in the coordinate system 40 arranged but positioned closest to each other, at an intersection 23 be summarized.

In step IV. The intersection points 23 which is characterized by the superposition of more than two points 18th , 36 from different point clouds 17th , 22nd , 44 result from other threshold values that are greater than " 2 "Are, here then at least" 3 ", be identified. As a result, the robustness of the method can be further increased because, for. B. several operating points 6th , 7th , 8th approached and the phase positions 1 , 3 the camshafts 2 , 4th can be checked. The higher the threshold value and the higher the number of independently determined point clouds 17th , 22nd , 44 is, the more precise the actual camshaft phase position can be 1 , 3 to be determined.

With the method, the intersections 41 any number of point clouds 17th , 22nd , 44 can be evaluated without the respective point cloud 17th , 22nd , 44 a condition regarding continuity, uniqueness, differentiability, etc. would have to meet.

At least step III. or Step IV. can also apply to only a partial area 43 a point cloud 17th , 22nd , 44 (in 4th it can be seen that only the partial area shown as a solid line 43 the second point cloud 22nd is considered). This allows certain sub-areas 43 individual point clouds 17th , 22nd , 44 excluded, in which z. B. Intersections 23 of the point clouds considered 17th , 22nd , 44 may be viewed as implausible.

In 5 is shown that the first point cloud 17th taking into account the deviation 25th the phase positions 1 , 3 the different operating points 6th , 7th is shifted, and the shifted first point cloud 17th (about the deviation 25th shifted down along the vertical direction and to the left along the horizontal direction) and the second point cloud 22nd as well as the shifted first point cloud 17th and the third point cloud 44 together an intersection 41 with two intersections 23 form.

The shift takes place along the horizontal direction in order to reflect the change in the assumed intake camshaft phase position, e.g. B. from the first intake camshaft phase position 14th towards the second intake camshaft phasing 19th , to compensate. Correspondingly, the shift takes place along the vertical direction in order to reflect the change in the assumed exhaust camshaft phase position, e.g. B. from the first exhaust camshaft phase position 15th towards the second exhaust camshaft phase position 20th , to compensate.

When approaching different operating points 6th , 7th which have the same characteristic 16 , 21 but different phase positions are recorded 14th , 15th , 19th , 20th can be adjusted, the deviation 25th the phase positions 14th , 15th , 19th , 20th between the different operating points 6th , 7th be determined. This deviation 25th is therefore the difference in the phase positions 14th , 15th , 19th , 20th to each other, ie the difference between the phase position 14th , 15th , 19th , 20th the respective camshaft 2 , 4th in the first operating point 6th and in the second operating point 7th . It is assumed that for the series internal combustion engine 5 set phase positions 14th , 15th , 19th , 20th the same boundary conditions apply, e.g. B. mounting errors, encoder wheel, sensor, etc., and that with it the relative adjustment between the phase positions 14th , 15th , 19th , 20th can be set and recorded with high quality. It is therefore assumed that there is a deviation 25th between the different operating points 6th , 7th set (possibly not actually present) phase positions 14th , 15th , 19th , 20th the deviation 25th corresponds to that between the actual phase positions actually present 1 , 3 is present.

In step f) can be based on the deviation 25th and knowing the models 9 , 10 the one point cloud 17th or the function or the line in the diagram can be corrected so that point clouds that correspond to one another 17th , 22nd and to form the intersection 41 can be used.

The point of intersection determined in step f) 23 the point clouds 17th , 22nd forms in particular the combination of actual phase positions 1 , 3 , i.e. the actual intake camshaft phase position 1 and the actual exhaust camshaft phasing 3 that are in the operating points 6th , 7th 8th actually exist.

These values of the actual phase positions 1 , 3 can now be used to determine the values used up to this current point in time for the assumed phase positions 14th , 15th , 19th , 20th (e.g. the first phase positions 14th , 15th and the second phase positions 19th , 20th ) to recalibrate. So there is a difference in the actual phase position 1 , 3 of the camshaft in question 2 , 4th of the phase position set up to then 14th , 15th , 19th , 20th determined and based on this deviation, the control variable 30th in the control unit 29 changed. After that, the series internal combustion engine should be used 5 set (target) phase position 14, 15, 19, 20, i.e. z. B. the first or second phase position, the actually present respective actual phase position 1 , 3 correspond.

List of reference symbols

1

Actual intake camshaft phasing

2

Intake camshaft

3

Actual exhaust camshaft phase position

4th

Exhaust camshaft

5

Series internal combustion engine

6th

first operating point

7th

second operating point

8th

third operating point

9

first model

10

second model

11

first pressure signal

12th

second pressure signal

13th

third pressure signal

14th

first intake camshaft phasing

15th

first exhaust camshaft phasing

16

first feature

17th

first point cloud

18th

first point

19th

second intake camshaft phasing

20th

second exhaust camshaft phasing

21

second feature

22nd

second point cloud

23

Intersection

24

Cutting angle

25th

deviation

26th

Suction side

27

Outlet side

28

Pressure sensor

29

Control unit

30th

Control variable

31

crankshaft

32

piston

33

cylinder

34

Inlet valve

35

outlet valve

36

second point

37

first coordinate

38

second coordinate

39

third coordinate

40

Coordinate system

41

Intersection

42

Grid

43

Sub-area

44

third point cloud

Claims (10)

Method for determining an intersection point (23) of at least two point clouds (17, 22), wherein each point cloud (17, 22) comprises a plurality of points (18, 36), each point (18, 36) by a plurality of coordinates (37, 38, 39) is defined and thus has a defined position in a multi-dimensional coordinate system (40); wherein the method comprises at least the following steps: I. determining a first point cloud (17) with a plurality of first points (18), II. Determining a second point cloud (22) with a plurality of second points (36), III. Assigning a value “1” for each point (18, 36) of each point cloud (17, 22) and assigning a value “zero” for every other position in the coordinate system (40); IV. Adding the first point cloud (17) and the second point cloud (22) and determining an intersection (41) of the point clouds (17, 22), the intersection (41) being formed by at least one intersection (23) which is located in the Coordinate system (40) is arranged at a position which is a threshold value of at least 2. Procedure according to Claim 1 , wherein the method for determining a combination of an actual intake camshaft phase position (1) of an intake camshaft (2) and an actual exhaust camshaft phase position (3) of an exhaust camshaft (4) of a series internal combustion engine (5) is carried out; the method being carried out during operation of the series internal combustion engine (5) and the respective actual phase position (1, 3) of the camshafts (2, 4) in relation to an operating point (6, 7, 8) of the series internal combustion engine (5) is determined; wherein the intersection (23) of the point clouds (17, 22) determined from the intersection (41) represents the actual intake camshaft phase position (1) and the actual exhaust camshaft phase position (3). Procedure according to Claim 2 , at least comprising the following steps: a) determining models (9, 10) on a reference internal combustion engine for different operating points (6, 7, 8), each model (9, 10) for one operating point (6, 7, 8) of the reference internal combustion engine, a relationship between a pressure signal (11, 12, 13) determined on the reference internal combustion engine as a function of the actual intake camshaft phase position (1) and the actual exhaust camshaft phase position (3) of the respective operating point ( 6, 7, 8) represents; b) Approaching a first operating point (6) with the series internal combustion engine (5) and detecting a first pressure signal (11) at a first intake camshaft phase position (14) and a first exhaust camshaft phase position (15) and determining a first feature (16) ) from the first pressure signal (11); c) determining the first point cloud (17) according to step I., wherein the individual first points (18) of the first point cloud (17) by the combinations of the actual intake camshaft phase position (1) and derived from the models (9, 10) the actual exhaust camshaft phase position (3) for the first feature (16) determined in step b) are formed; d) determining a second feature (21) from the first pressure signal (11) or approaching a second operating point (7) with the series internal combustion engine (5) and detecting a second pressure signal (12) at a second intake camshaft phase position (19) and a second exhaust camshaft phase position (20) and determining a second feature (21) from the second pressure signal (12); e) determining the second point cloud (22) according to step II., wherein the individual second points (36) of the second point cloud (22) by the combinations of the actual intake camshaft phase position (1) and derived from the models (9, 10) the actual exhaust camshaft phase position (3) for the second feature (21) determined in step d) are formed; f) forming the intersection (41) of the first point cloud (17) and the second point cloud (22); wherein an intersection (23) of the point clouds (17, 22) determined from the intersection (41) represents the actual intake camshaft phase position (1) and the actual exhaust camshaft phase position (3). Procedure according to Claim 3 , wherein at least one of the operating points (6, 7, 8) approached in steps b) and d) is selected as a function of a suitability determined on the reference internal combustion engine (5), the suitability having the largest possible cutting angle (24) comprises point clouds (17, 22) determined in steps c) and e) and intersected in step f). Method according to one of the preceding Claims 3 and 4th , the actual phase positions (1, 3) determined in step f) in a control unit (29) of the series internal combustion engine (5) for correcting control variables ( 30) can be used. Method according to one of the preceding claims, wherein at least for the adding according to step IV. A resolution of a grid (42) of the coordinate system (40) is changed so that points (18, 36) of point clouds (17, 22) are more accurate or less accurate to be dissolved; with a lower resolution points (18, 36) of different point clouds (17, 22), which are arranged at different positions in the coordinate system (40) but are positioned closest to one another, are combined to form a point of intersection (23). Method according to one of the preceding claims, wherein in step IV. The intersection points (23), which result from the superposition of more than two points (18, 36) from different point clouds (17, 22), are replaced by other threshold values which are greater than 2 are to be identified. Method according to one of the preceding claims, wherein at least step III. or step IV. is applied to only a partial area (43) of at least one point cloud (17, 22). Control unit (29) for an internal combustion engine (5), the control unit (29) being equipped, configured or programmed to carry out the method according to one of the preceding claims. Internal combustion engine (5), at least comprising a crankshaft (31), an adjustable intake camshaft (2), an adjustable exhaust camshaft (4), at least one piston (32) connected to the crankshaft (31) and a cylinder (33) in which the Piston (32) performs stroke movements, as well as an intake side (26) via which at least air can be supplied to the cylinder (33) via at least one inlet valve (34) actuatable by the inlet camshaft (2), and an outlet side (27) via which exhaust gas can be discharged from the cylinder (33) via at least one exhaust valve (35) which can be actuated by the exhaust camshaft (4); where in the The suction side (26) or at least one pressure sensor (28) for detecting pressure signals (11, 12, 13) is arranged in the outlet side (27); wherein the internal combustion engine (5) further comprises a control device (29) that is used to carry out the method according to one of the preceding Claims 1 to 8th is executed appropriately.

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