DE102017200824A1 - Method and device for adapting a valve lift adjustment of a charge exchange valve of an internal combustion engine - Google Patents

Abstract

The invention relates to a method for operating an internal combustion engine (1) with a valve adjustment, comprising the following steps: - operating the internal combustion engine (1) with an operating characteristic of a charge exchange valve (6, 7) as a function of a correction variable which is a phase position of an opening phase of the charge exchange valve ( 6, 7), - adjusting the operating characteristic of the charge exchange valve (6, 7), - adjusting (S6) the correction quantity as a function of a progression of the rotational speed before and after the switching over of the operating characteristic of the charge exchange valve (6, 7).

Description

Technical area

The invention relates to internal combustion engines, in particular internal combustion engines, in which an operating characteristic of charge exchange valves is adjustable. Furthermore, the present invention relates to the adaptation of a camshaft phase adjustment for a valve lift of an internal combustion engine.

Technical background

In modern gasoline engines can be provided to minimize fuel consumption at partial load and at low speed ranges adjustments to the operating characteristics of gas exchange valves. The operating characteristic indicates a course of an opening phase including the valve lift and the opening duration and a phase position of the opening phase relative to a crankshaft angle of a crankshaft of the internal combustion engine. The changes in the operating characteristics of charge cycle valves can be realized with an intake valve lift switching system and a camshaft phaser, which can provide a significant fuel economy benefit by reducing charge cycle losses at the throttle. In particular, it must be switched to a larger valve lift at high loads, as can not over the entire operating range of the gasoline engine away an optimized engine operation can be represented by a uniform operating characteristic of the intake valve.

The publication DE10 2012 002 255 A1 describes a method in which engine speeds are determined based on positions of teeth of a gear rotating with a crankshaft and based on a crankshaft position signal generated by a crankshaft position sensor, wherein an indicated average effective pressure (IMEP ) is determined for a combustion cycle of a cylinder of an engine based on squares of first and second ones of the engine speeds during the combustion cycle, and wherein a failure in a variable valve lift (VVL) mechanism of the cylinder is selectively diagnosed based on the IMEP.

The publication DE10 2007 053 783 B4 discloses a diagnostic system for a discrete variable valve lift system of an internal combustion engine, comprising: a fast Fourier transform module that generates a frequency content signal based on an FFT method and a valve kick sensor signal; and a malfunction module that selectively diagnoses a malfunction of a discrete variable valve lift system based on the frequency content signal; wherein the malfunction module sets a malfunction signal based on a frequency range based on the engine speed.

Disclosure of the invention

According to the invention, a method for adapting a changeover of an operating characteristic of a charge exchange valve, in particular an intake valve of an internal combustion engine according to claim 1, and a device and an internal combustion engine according to the independent claims are provided.

Further embodiments are specified in the dependent claims.

• - Betreiben des Verbrennungsmotors mit einer Betriebscharakteristik eines Ladungswechselventils abhängig von einer Korrekturgröße, die eine Phasenlage einer Öffnungsphase des Ladungswechselventils bestimmt;
• - Umschalten der Betriebscharakteristik des Ladungswechselventils;
• - Anpassen der Korrekturgröße abhängig von einem Verlauf der Drehzahl vor und nach der Umschaltung der Betriebscharakteristik des Ladungswechselventils.

According to a first aspect, a method for operating an internal combustion engine with a valve adjustment is provided, comprising the following steps:

• Operating the internal combustion engine with an operating characteristic of a charge exchange valve as a function of a correction variable which determines a phase position of an opening phase of the charge exchange valve;
• - switching the operating characteristic of the charge exchange valve;
• - Adjusting the correction variable depending on a curve of the speed before and after the switching of the operating characteristic of the charge exchange valve.

Since the change in the stroke characteristic of the charge exchange valve, the amount of air supplied in the cylinders changes significantly, the charge exchange valve torque neutral switching the operating characteristics of other operating parameters, such as fuel quantity, throttle position, Inertgasmenge, position of the ignition angle and position of the injection timing and the number of injections and the like be adjusted. This adjustment is based on a model that depends on the set intake valve lift and the operating point. In this case, optimal operating parameters for a specific driver's desired torque can be specified.

If the operating characteristic of the charge exchange valve is changed during the current driving operation, a change of the underlying torque model in the engine control takes place at the same time, and the corresponding operating parameters are adapted. In charge exchange valves with switchable valve lift, the phase position of the opening phase of the charge exchange valve be varied in time with respect to a crankshaft angle of a crankshaft. In this way, the phase position can be adjusted and the torque model can be changed at the same time, so that a change-neutral switching between the operating characteristics of the charge-reversal valve is possible.

A strategy for such switching between the operating characteristics is to set for the various valve strokes the timing of closing the charge cycle valve between a time before bottom dead center piston movement in the cylinder concerned and a time after bottom dead center at which equal air fillings are achieved , This can make it possible to represent a consumption-optimal switching, so that no torque-reducing Zündwinkeleingriff before or after the changeover to compensate for the filling differences is required.

However, there is a problem in that for a torque-neutral changeover of the operating characteristic of the charge exchange valve thus carried out, the phase position of the opening phase of the charge exchange valve must be positioned very precisely. Since the adjustment takes place with a variable camshaft adjuster, which is subject to tolerances due to the tolerances in the sensor technology and, in particular, due to aging effects of the camshaft adjuster, the torque-neutral changeover can not be realized without corrective interventions.

An idea of the above method is to adapt the adjustment of the phase position of the opening phase of the charge exchange valve, the operating point dependent on the set valve lift depends. This can be done by comparing the dynamic behavior of the internal combustion engine before or after switching the operating characteristic of the charge exchange valve. For this purpose, the observation of the course of the speed is suitable. By evaluating the progressions of the rotational speed before and after the changeover, it can be decided whether the changeover of the operating characteristic of the charge exchange valve has been carried out torque-neutral. Optionally, an adaptation of the phase position of the opening phase of the charge exchange valve can be made upon detection of a torque error. The adaptation of the corresponding correction variable makes it possible to perform the changeover of the operating characteristic of the charge exchange valve torque neutral and occurring tolerances in the sensors of the camshaft adjuster, and especially tolerances that occur due to aging effects in the camshaft actuator to compensate.

Furthermore, a time for switching over the operating characteristic of the charge exchange valve can be determined depending on an operating point of the internal combustion engine or depending on a change in the operating point of the internal combustion engine, wherein the operating point is determined in particular by a load and / or a rotational speed of the internal combustion engine.

According to one embodiment, the switching over of the operating characteristic of the charge exchange valve may include changing a maximum valve lift and / or a duration of an opening phase of the charge exchange valve.

It can be provided that the correction variable is stored as a function of the operating point and, during operation of the internal combustion engine, the adjustment of the phase position is made by operating point-dependent selection of the correction variable.

Furthermore, the correction quantity can be stored as a function of the switching direction and, when the internal combustion engine is operated, the phase position can be adjusted by selecting the correction variable corresponding to the respective switching direction.

It can be provided that the correction amount for the late shift / early shift of the opening phase is adjusted when it is determined when switching between operating characteristics from the small maximum valve lift to the high maximum valve lift by comparing the characteristics that the rotational speed after the switching is higher / lower as the expected speed.

According to an embodiment, adjusting the correction quantity depending on a progression of the rotational speed before and after the switching of the operating characteristic of the charge exchange valve can be performed by determining characteristics dependent on a rotational speed course before and after a changeover of the operating characteristic of the charge exchange valve, and by the correction variable being dependent on a comparison of the parameters are adjusted before and after the switching of the operating characteristic of the charge exchange valve.

In particular, the characteristic numbers may correspond to average values of rotational speed curves in a time window before and in a time window after the operating characteristic has been switched over.

Alternatively, one of the characteristics may be determined as an extrapolated rotation speed determined from the history of the rotation speed before the switching of the operation characteristic for a time point after the switchover, and another one of the characteristics a speed at the time after the changeover are determined.

• - den Verbrennungsmotor mit einer Betriebscharakteristik eines Ladungswechselventils abhängig von einer Korrekturgröße zu betreiben, die eine Phasenlage einer Öffnungsphase des Ladungswechselventils bestimmt;
• - die Betriebscharakteristik des Ladungswechselventils umzuschalten; und
• - die Korrekturgröße abhängig von einem Verlauf der Drehzahl vor und nach der Umschaltung der Betriebscharakteristik des Ladungswechselventils anzupassen.

In another aspect, an apparatus for operating an internal combustion engine having a valve timing is provided, the apparatus being configured to:

• to operate the internal combustion engine with an operating characteristic of a charge exchange valve as a function of a correction variable which determines a phase position of an opening phase of the charge exchange valve;
• - to switch the operating characteristics of the charge cycle valve; and
• - Adjust the correction variable depending on a curve of the speed before and after the switching of the operating characteristic of the charge exchange valve.

• - einen Verbrennungsmotor mit mindestens einem Zylinder mit Ladungswechselventilen;
• - eine Ventilhubverstellung zum Einstellen eines Ventilhubs mindestens eines der Ladungswechselventile;
• - einen Nockenwellensteller, der ausgebildet ist, um eine Phasenlage einer Öffnungsphase des Ladungswechselventils einzustellen; und
• - die obige Vorrichtung.

In another aspect, an engine system is provided, comprising:

• an internal combustion engine having at least one cylinder with charge exchange valves;
• a valve lift adjustment for setting a valve lift of at least one of the charge exchange valves;
• - A camshaft actuator, which is designed to adjust a phase angle of an opening phase of the charge exchange valve; and
• - The above device.

list of figures

• 1 eine schematische Darstellung eines Verbrennungsmotors;
• 2 eine schematische Darstellung einer Einlassventilverstellung;
• 3 ein Flussdiagramm zur Veranschaulichung des Verfahrens zum Adaptieren einer Betriebscharakteristik eines Einlassventils bei einer Ventilhubumschaltung; und
• 4 ein Diagramm zur Veranschaulichung eines Drehzahlverlaufs bezüglich eines extrapolierten Drehzahlverlaufs während einer Umschaltung der Betriebscharakteristik.

Embodiments are explained below with reference to the accompanying drawings. Show it:

• 1 a schematic representation of an internal combustion engine;
• 2 a schematic representation of an intake valve adjustment;
• 3 a flowchart for illustrating the method for adapting an operating characteristic of an intake valve in a valve lift switching; and
• 4 a diagram illustrating a speed curve with respect to an extrapolated speed curve during a changeover of the operating characteristic.

Description of embodiments

1 shows a schematic representation of an internal combustion engine 1 , in particular a gasoline engine. The internal combustion engine 1 has a number, in the present embodiment, four cylinders 2 on, in which a piston (not shown) is movably arranged and with a crankshaft 3 is coupled. Movement of the pistons turns the crankshaft 3 driven in rotation in a conventional manner.

The internal combustion engine 1 Air is supplied via an air supply system 4 supplied, and combustion exhaust gases are via an exhaust system 5 dissipated. To intake air in the cylinders 2 these each have at least one inlet valve 6 and at least one exhaust valve 7 as charge exchange valves. Furthermore, an injection valve 8th be provided for the direct injection of fuel. Using one on the cylinders 2 arranged ignition device 9 can be an air-fuel mixture in the cylinders 2 be ignited in a corresponding combustion cycle.

The internal combustion engine 1 is designed as a gasoline engine and is operated according to a four-stroke principle known per se. For supplying fresh air into the cylinders 2 becomes the inlet valve 6 for the cylinder in question 2 opened before a compression stroke to compress them and to perform an ignition during the combustion stroke after injection of fuel. After the combustion cycle, the exhaust valves become 7 opened suitably to combustion exhaust gas in the exhaust tract 5 omit.

The valve operation of the intake and exhaust valves 6 . 7 is at a crankshaft position of the crankshaft 3 coupled. To reduce charge cycle losses, ie to improve the consumption characteristics, the operating characteristics of the intake valves 6 be changed. The operating characteristic indicates a course of an opening phase including the valve lift and the opening duration and a phase position of the opening phase relative to a crankshaft angle of a crankshaft of the internal combustion engine.

Especially for the intake valves 6 can be a valve lift adjustment 11 provided by the valve lifts, ie the maximum valve lifts during an opening phase of the respective intake valves and the total opening duration of the respective intake valves 6 , between two or more than two settings can be adjusted. In addition, the phase angle of the opening phase of the intake valves 6 with respect to the crankshaft angle by means of a camshaft adjustment 10 be set variably.

In 2 is schematically a Ventilbetriebverstellsystem 20 shown for a valve lift and a camshaft adjustment. It is a camshaft 21 shown a first cam 22 and a second cam 23 that has axially offset on the camshaft 21 are arranged. The cams 22 . 23 apply a plunger during their rotary motion 24 of the inlet valve 6 , The first and the second cam 22 . 23 have different profiles, the different valve lifts an acted upon intake valve 6 to lead.

The cams 22 . 23 can be adjusted with the help of a valve lift actuator 25 move axially so that either the first cam 22 or the second cam 23 the pestle 24 of the inlet valve 6 applied. The camshaft 21 is via a toothed belt 26 with the crankshaft 3 via a camshaft gear 27 coupled, allowing a rotation of the crankshaft 3 to a corresponding rotation of the camshaft 21 leads and a crankshaft position is associated with a corresponding position of the camshaft.

Between a camshaft gear 27 on which the timing belt 26 is applied, and the camshaft 21 is a camshaft actuator 28 provided that a phase angle between the rotation of the crankshaft 3 and the rotation of the camshaft 21 can adjust. The setting can be fully variable and is preferably carried out so that when switching between the first and second cam 22 . 23 for setting the corresponding operating characteristic, a corresponding phase position between the crankshaft 3 and the camshaft 21 through the camshaft actuator 28 is set. The camshaft adjustment is to be adjusted during a changeover so that the air charge (ie, the amount of air flowing into the cylinder), during the opening phase of the intake valves 6 in the cylinders 2 before and after the changeover are essentially identical.

It is a control unit 15 provided, based on state variables of the internal combustion engine 1 , which are based on sensor signals and / or model sizes, control variables for various positioners and a default size, which may for example depend on a driver's desired torque, the control of encoders, in particular a throttle valve, the Ventilbetriebverstellsystems 20 , injectors, or the like, to achieve an engine torque to be provided by the default size. In particular, the control unit 15 for each discrete setting of the valve lift actuator 25 the camshaft actuator 28 to control by appropriately operating point-dependent modeled phase control variables in order to achieve a torque neutral switching as possible. The phase control variables are specified by a correspondingly applied camshaft actuator model.

In 3 a flowchart illustrating the method for adapting an operating characteristic of a charge cycle valve of an internal combustion engine is shown. The charge exchange valve corresponds to an intake valve, and the following procedure becomes for one of the cylinders 2 of the internal combustion engine 1 described.

In step S1, a rotational speed of the internal combustion engine is continuously 1 recorded.

In step S2, it is checked whether a valve lift switching should take place. This decision is made based on the current operating point and based on the default value V. The instantaneous operating point can be done for example by a speed and / or load and other parameters. If it is determined that a changeover of the operating characteristic of the intake valve is to be carried out (alternative: yes), the method is continued with step S3; otherwise, the system jumps back to step S1.

In step S3, the valve lift 25 for changing the operating characteristic of the intake valve 6 driven. These are the cams 22 . 23 axially displaced such that a correspondingly different cam engages the plunger of the respective intake valve 6 arrives.

At the same time, in step S4, the camshaft actuator 28 controlled to a phase angle of the opening phase of the intake valve 6 passing through the contour of the correspondingly activated cam 22 . 23 is predetermined to adjust so that one in the cylinder 21 reaching air filling to the previously in the cylinder 2 reached air filling is identical, if no torque change is requested by the default size, or a corresponding to a given air filling curve air filling, which results from a possible acceleration or deceleration behavior corresponds. The timing of the adjustment of the phase angle by the camshaft actuator 28 is set operating point dependent and takes into account a correction quantity that can be provided to compensate for component tolerances and aging effects. The correction quantity corrects a shift in the phase position of the opening phase of the intake valve with respect to the crankshaft angle.

After the switching, the course of the rotational speed is recorded for a predetermined period of time in step S5.

In step S6, the correction amount is adjusted depending on a speed history characteristic prior to the shift detected in step S1 and a speed history characteristic recorded after switching the operation characteristic of the intake valve , It can be for the different switching directions, namely from a high maximum valve lift with a longer opening duration to a lower valve lift with a shorter opening duration, separate correction variables are determined.

The characteristic numbers may be, for example, mean values of rotational speed curves in a time window before and within a time window after the switching between the operating characteristics. Furthermore, a speed profile extrapolated from the first time window and the speed curve actually determined in step S5 can also be compared with one another and it can be determined from this whether an adaptation of the correction quantity is necessary or not.

In 4 For example, a curve of the rotational speed during a switching operation is shown by way of example as a curve K1. Furthermore, an extrapolated from a course of the speed in a time window T1 before switching (curve K2) is shown. It can be seen that after the switchover during a switch-over period U, an increased rotational speed is erroneously reached, which deviates from the extrapolated profile of the rotational speed.

If it is determined, for example, that the speed after the changeover is greater than the speed before the changeover or when the speed curve can be expected before the changeover, then it is assumed that an excessively large engine torque is provided by the switching over of the operating characteristic of the intake valve. The correction variable is now adjusted so that, taking into account the correction variable with a corresponding changeover of the operating characteristics, a lower engine torque is achieved after the switchover.

• - Die Korrekturgröße wird zur Spätverschiebung der Öffnungsphase angepasst, wenn bei einer Umschaltung zwischen Betriebscharakteristiken von dem geringen maximalen Ventilhub zu dem hohen maximalen Ventilhub durch Vergleich der Kenngrößen festgestellt wird, dass die Drehzahl nach der Umschaltung höher ist als die zu erwartende Drehzahl.
• - Die Korrekturgröße wird zur Frühverschiebung der Öffnungsphase angepasst, wenn bei einer Umschaltung zwischen Betriebscharakteristiken von dem geringen maximalen Ventilhub zu dem hohen maximalen Ventilhub durch Vergleich der Kenngrößen festgestellt wird, dass die Drehzahl nach der Umschaltung niedriger ist als die zu erwartende Drehzahl.
• - Die Korrekturgröße wird zur Frühverschiebung der Öffnungsphase angepasst, wenn bei einer Umschaltung zwischen Betriebscharakteristiken von dem hohen maximalen Ventilhub zu dem niedrigen maximalen Ventilhub durch Vergleich der Kenngrößen festgestellt wird, dass die Drehzahl nach der Umschaltung höher ist als die zu erwartende Drehzahl.
• - Die Korrekturgröße wird zur Spätverschiebung der Öffnungsphase angepasst, wenn bei einer Umschaltung zwischen Betriebscharakteristiken von dem hohen maximalen Ventilhub zu dem niedrigen maximalen Ventilhub durch Vergleich der Kenngrößen festgestellt wird, dass die Drehzahl nach der Umschaltung niedriger ist als die zu erwartende Drehzahl.

If differences between the speed characteristics in the time window before the switchover and after the changeover are detected in detail, the used correction quantity can be adjusted incrementally, as follows:

• - The correction value is adapted to the late shift of the opening phase, if it is determined in a switch between operating characteristics of the small maximum valve lift to the high maximum valve lift by comparing the characteristics that the speed after switching is higher than the expected speed.
• - The correction value is adapted to the early shift of the opening phase, when it is determined in a switch between operating characteristics from the small maximum valve lift to the high maximum valve lift by comparing the characteristics that the speed after switching is lower than the expected speed.
• - The correction value is adapted to the early shift of the opening phase, when it is determined in a switch between operating characteristics of the high maximum valve lift to the low maximum valve lift by comparing the characteristics that the speed after switching is higher than the expected speed.
• - The correction value is adapted to the late shift of the opening phase, when it is determined in a switch between operating characteristics from the high maximum valve lift to the low maximum valve lift by comparing the characteristics that the speed after switching is lower than the expected speed.

The adjustment of the correction quantities can thus be effected by successive change of the respective correction variable, depending on whether a deviation of the rotational speed has occurred in a moment-neutral changeover with respect to the expected speed curve.

In step S7, the camshaft actuator is driven in response to the applied by the correction amount phase control variable resulting from the camshaft actuator model.

The correction variable can be operating point-dependent, for example, depending on a rotational speed and a load of the internal combustion engine 1 be stored so that during operation, a corresponding adaptation of the phase control variable can be carried out operating point-dependent.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102012002255 A1 [0003]
• DE 102007053783 B4 [0004]

Claims (13)

Method for operating an internal combustion engine (1) with a valve adjustment, comprising the following steps: - Operating the internal combustion engine (1) with an operating characteristic of a charge exchange valve (6, 7) depending on a correction variable which determines a phase position of an opening phase of the charge exchange valve (6, 7); - Switching the operating characteristic of the charge exchange valve (6, 7); - Adjustment (S6) of the correction variable depending on a curve of the rotational speed before and after the switching of the operating characteristic of the charge exchange valve (6, 7). Method according to Claim 1 wherein a time for switching the operating characteristic of the charge exchange valve (6, 7) depending on an operating point of the internal combustion engine (1) or depending on a change in the operating point of the internal combustion engine (1) is determined, the operating point in particular by a load and / or a Speed of the internal combustion engine (1) is determined. Method according to Claim 1 or 2 wherein the switching over of the operating characteristic of the charge exchange valve (6, 7) comprises changing a maximum valve lift and / or a duration of an opening phase of the charge exchange valve (6, 7). Method according to one of Claims 1 to 3 , wherein the correction variable is stored operating point-dependent and when operating the internal combustion engine (1), the adjustment of the phase position by operating point-dependent selection of the correction variable is made. Method according to one of Claims 1 to 4 in which the correction quantity is stored as a function of the switching direction and, when the internal combustion engine (1) is operated, the phase position is adjusted by selecting the correction variable corresponding to the respective switching direction. Method according to one of Claims 1 to 5 , wherein the correction amount for late shift / early shift of the opening phase is adjusted when it is determined in a switch between operating characteristics from the small maximum valve lift to the high maximum valve lift by comparing the characteristics that the speed after the changeover is higher / lower than expected Rotation speed. Method according to one of Claims 1 to 6 , wherein the adjustment of the correction variable depending on a curve of the rotational speed before and after the switching of the operating characteristic of the charge exchange valve (6, 7) is performed by dependent on a speed curve characteristics before and after switching the operating characteristic of the charge exchange valve (6, 7) determined and in that the correction quantity is adjusted as a function of a comparison of the parameters before and after the switching over of the operating characteristic of the charge exchange valve (6, 7). Method according to Claim 7 wherein the indices correspond to mean values of rotational speed curves in a time window before and in a time window after the operating characteristic has been switched over. Method according to Claim 7 wherein a characteristic is determined as an extrapolated rotational speed determined from the history of the rotational speed prior to the switching of the operating characteristic for a time point after the changeover, and a characteristic as a rotational speed at the time point after the changeover. Device for operating an internal combustion engine (1) with a valve adjustment, the device being designed to: - to operate the internal combustion engine (1) with an operating characteristic of a charge exchange valve (6, 7) dependent on a correction variable which determines a phase position of an opening phase of the charge exchange valve (6, 7); to switch over the operating characteristic of the charge exchange valve (6, 7); and - Adjust the correction variable depending on a curve of the speed before and after the switching of the operating characteristics of the charge exchange valve (6, 7). Engine system (1) comprising: - an internal combustion engine (2) having at least one cylinder (2) with charge exchange valves (6, 7); a valve lift adjustment for setting a valve lift of at least one of the charge exchange valves (6, 7); - A camshaft actuator (28) which is designed to adjust a phase position of an opening phase of the charge exchange valve; and - a device according to Claim 10 , Computer program adapted to perform all steps of a method according to one of Claims 1 to 9 perform. Machine-readable storage medium on which a computer program is based Claim 12 is stored.

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