EP3679237A1

EP3679237A1 - Method for checking the function of a pressure sensor in the air intake tract or exhaust gas outlet tract of an internal combustion engine during operation, and motor control unit

Info

Publication number: EP3679237A1
Application number: EP18768813.0A
Authority: EP
Inventors: Tobias Braun; Frank Maurer; Jürgen DINGL; Sven-Michael Eisen
Original assignee: Vitesco Technologies GmbH
Current assignee: Vitesco Technologies GmbH
Priority date: 2017-09-08
Filing date: 2018-09-04
Publication date: 2020-07-15
Anticipated expiration: 2038-09-04
Also published as: BR112020004203A2; US20200200113A1; EP3679237B1; KR20200047674A; JP2020532680A; DE102017215849B4; CN111133184A; US11293368B2; CN111133184B; DE102017215849A1; WO2019048416A1; KR102283112B1

Abstract

The invention relates to a method for checking the function of a pressure sensor (44) in the air intake tract (20) or exhaust gas outlet tract (30) of an internal combustion engine (1) during operation and to a motor control unit (50) for carrying out the method. On the basis thereof, dynamic pressure oscillations of the intake air in the air intake tract (20) or of the exhaust gas in the exhaust gas outlet tract (30) of the pertinent internal combustion engine (1) are measured during operation by means of the pertinent pressure sensor (44), and using a discrete Fourier transformation (DFT) for multiple chosen signal frequencies (SF...X), a respective value of a determined operation characteristic (Bchk_W1...X) of the internal combustion engine (1) and deviation values (Aw_W1...Y) of the values ascertained for the different signal frequencies (SF1...X) with respect to one another are ascertained on the basis of the obtained pressure oscillation signal (DS_S). Based on whether ascertained deviation values (Aw_W1...Y) fall below or exceed a specified threshold (Aw_Gw), the proper function of the pressure sensor (44) is confirmed (DSens=ok) or a malfunction (Dsens_Ffkt) of the pressure sensor (44) is diagnosed. Thus, a monitoring of the proper function of the pressure sensor (44) is achieved, and in the event of a malfunction, corresponding measures are taken in order to prevent a malfunction of the internal combustion engine and an emission of pollutants which is increased on the basis thereof as the case may be.

Description

description

Method for checking the function of a pressure sensor in the air intake tract or exhaust gas outlet tract of a combustion engine in operation and engine control unit

The present invention relates to a method with which a respective pressure sensor which is arranged for measuring pressure in the air intake tract or in the exhaust gas outlet tract of an internal combustion engine can be checked for its faultless function, in particular with regard to its dynamic behavior, in order to ensure trouble-free and in particular to ensure lawful operation of the respective internal combustion engine over the entire operating period with respect to the emission of pollutants ^¬ . Furthermore, the present invention relates to a motor control unit which is adapted to carry out the inventions ^¬ inventive method.

Reciprocating internal combustion engines, which are shortened in the context of this description also referred to only as internal combustion engines, have one or more cylinders in each of which a reciprocating piston is arranged. To illustrate the principle of a reciprocating internal combustion engine, reference is made below to FIG. 1, which shows by way of example a cylinder of an optionally also multi-cylinder internal combustion engine with the most important functional units.

The respective reciprocating piston 6 is arranged linearly movable in the respective cylinder 2 and closes with the cylinder 2 a combustion chamber 3 a. The respective reciprocating piston 6 is connected to a respective crank pin 8 via a so-called connecting rod 7

Crankshaft 9 is connected, wherein the crank pin 8 is arranged eccentrically to the crankshaft axis of rotation 9a. By the combustion of a fuel-air mixture in the combustion chamber 3, the stroke ^¬ piston 6 is driven linearly "downwards". The translational Lifting movement of the reciprocating piston 6 is transmitted by means of connecting rod 7 and crank pin 8 to the crankshaft 9 and converted into a rotational movement of the crankshaft 9, which moves the reciprocating piston 6 after overcoming a bottom dead center in the cylinder 2 again in the opposite direction "up" to a top dead center. In order to enable continuous operation of the internal combustion engine 1, the combustion chamber 3 must first be filled with the fuel-air mixture during a so-called working cycle of a cylinder 2, the fuel-air mixture in the combustion chamber 3 compressed, then ignited and expanded to drive the piston 6 are burned and finally the remaining after combustion exhaust gas are expelled from the combustion chamber 3. Continuous repetition of this process results in a continuous operation of the internal combustion engine 1 with delivery of a work proportional to the combustion energy.

Depending on the engine concept is a working cycle of the cylinder 2 in two over a crankshaft revolution (360 °) distributed clocks

(Two-stroke engine) or divided into four over two crankshaft revolutions (720 °) distributed clocks (four-stroke engine).

Drivers of motor vehicles of four-stroke engine ^¬ has prevailed until today. In an intake stroke, wherein movement of the reciprocating piston From ^¬ 6 Windwärts, fuel-air mixture or only fresh air is introduced (at direct fuel injection) from the air-intake duct 20 into the combustion chamber. 3 In the following compression stroke, the fuel-air mixture or the fresh air is compressed in the combustion chamber 3 and optionally separately fuel injected by means of a, belonging to a fuel supply system, injector 5 directly into the combustion chamber 3, during upward movement of the reciprocating piston 6. In the following working cycle, the fuel-air mixture is ignited by means of a spark plug 4, expanded burned and relaxed in downward movement of the reciprocating piston 6 to deliver work. Finally, in one Ausschiebetakt, with renewed upward movement of the reciprocating piston 6, the remaining exhaust gas from the combustion chamber 3 into the exhaust system 30 is ejected. The delimitation of the combustion chamber 3 to the air intake tract 20 or exhaust tract 30 of the internal combustion engine is usually and in particular zugrungegelegegten example via intake valves 22 and exhaust valves 32. The control of these valves is carried out according to the current state of the art via at least one camshaft. The example shown has one

Inlet camshaft 23 for actuating the intake valves 22 and an exhaust camshaft 33 for actuating the exhaust ^¬ valves 32. Between the valves and the respective cam shaft more, not shown here, mechanical components for power transmission are present, which may also include a valve clearance compensation (eg tappets,

Rocker arm, rocker arm, push rod, hydraulic tappet, etc.).

The intake camshaft 23 and the exhaust camshaft 33 are driven by the internal combustion engine 1 itself. For this, the intake camshaft 23 and the exhaust camshaft 33 are respectively controlled via suitable intake camshaft control adapters 24 and exhaust camshaft control adapters 34 such as gears, sprockets, or pulleys by means of a timing transmission 40 , Which, for example, a gear transmission, a timing chain or a timing belt, in a predetermined position to each other and to the crankshaft 9 via a corresponding crankshaft control adapter 10, which is designed as a gear, sprocket or belt ^¬ wheel, coupled to the crankshaft 9. Through this connection, the rotational position of the intake camshaft 23 and the exhaust camshaft 33 is defined in principle in relation to the rotational position of the crankshaft 9. FIG. 1 shows by way of example the coupling between inlet camshaft 23 and exhaust camshaft 33 and the crankshaft 9 shown by means of pulleys and timing belt.

The rotation angle of the crankshaft, which has been covered by a working cycle, is referred to below as the working phase or simply phase. A covered within a working phase angle of rotation of the crankshaft is referred to as corresponding phase angle ^¬ . The respective current crankshaft phase ^¬ angle of the crankshaft 9 can be detected continuously by means of a connected to the crankshaft 9 or the crankshaft control adapter 10 position sensor 43 and an associated crankshaft position sensor 41. In this case, the position sensor can be designed, for example, as a toothed wheel with a plurality of teeth distributed equidistantly over the circumference, wherein the number of individual teeth determines the resolution of the crankshaft phase angle signal.

Likewise, if appropriate, the current phase angles of the intake camshaft 23 and the exhaust camshaft 33 may additionally be detected continuously by means of corresponding position sensors 43 and associated camshaft load sensors 42.

Since the respective crank pin 8 and with it the reciprocating piston 6, the intake camshaft 23 and with it the respective intake valve 22 and the exhaust camshaft 33 and with it the respective exhaust valve 32 move through the predetermined mechanical coupling in predetermined relation to each other and in dependence on the crankshaft rotation , these functional components go through the respective working phase synchronously with the crankshaft. The respective rotational positions of the intake camshaft, the off ^¬ lassnockenwelle and the crankshaft and the stroke positions of the reciprocating piston 6, intake valves 22 and exhaust valves 32 can thus, taking into account the respective gear ratios, predetermined by the crankshaft position sensor 41 Crankshaft phase angle of the crankshaft 9 are related. In an ideal internal combustion engine, a specific crankpin angle HZW (FIG. 2), a specific piston stroke, a specific intake camshaft angle and thus a specific intake valve lift as well as a specific exhaust camshaft angle and thus a specific exhaust valve lift can thus be assigned to each specific crankshaft phase angle. That is, all the components mentioned are in or move in phase with the rotating crankshaft. 9

In modern internal combustion engine 1, however, may be present to ^¬ additional actuators within the mechanical coupling link between the crankshaft 9 and inlet ^¬ camshaft 23 and the exhaust camshaft 33, for example integrated into the intake camshaft adapter 24 and the Auslassnockenwellenadapter 34 having a desired controllable phase offset between the crankshaft 9 and intake camshaft 23 and exhaust camshaft 33. These are known as so-called ^¬ phase adjuster in so-called variable valve trains.

Symbolically, an electronic, programmable Mo ^¬ tor control unit 50 (CPU) is shown for control of the motor functions, with signal inputs 51 for receiving the various sensor signals and with signal and Leis ^¬ tung outputs 52 for driving respective actuators and actuators and is equipped with an electronic processing unit 53 and an associated electronic storage unit 54.

For optimum operation of the internal combustion engine (in terms of emissions, consumption, power, smoothness, etc.) should be introduced during the intake stroke in the combustion chamber

Fresh gas charge to be known as best as possible to the other _r

Parameters for the combustion, such as the supplied, possibly directly injected fuel quantity to vote on it. The so-called charge exchange, ie the intake of fresh gas and the expulsion of the exhaust gas is largely dependent on the timing of the intake valves 22 and exhaust valves 32, ie the time course of the respective valve strokes with respect to the time course of the piston stroke and height and course the pressures in the air intake tract and in the exhaust gas outlet tract. In other words, the charge change in operation depends on the phase angles of the intake and exhaust valves in relation to the crankshaft phase angle and thus the Pha ^¬ senlage of the reciprocating piston in cooperation with the respective pressure curve in the air intake tract and in the exhaust gas outlet tract.

State of the art for determining the fresh gas charge and for tuning the control parameters of the internal combustion engine, is the measurement of a so-called reference Verbrennungsmo ^¬ tor in all operating conditions, for example, depending on the speed, the load, if necessary, the presettable by phasensteller Valve timing, possibly the operating parameters of exhaust gas turbocharger or compressor, etc. and the storage of these measurements or derivatives thereof or of the behavior reproducing model approaches on the engine control unit of a corresponding series internal combustion engine. All identically built internal combustion engines of the same series are then operated with this generated reference data set.

A, caused for example by manufacturing tolerances, deviation of the actual relative positions between intake and exhaust valves and the crankshaft phase angle or. the reciprocating position of a series internal combustion engine with respect to the ideal reference positions of the reference combustion ^¬ engine, ie a phase difference of the intake valve, the Auslassventilhubs and optionally the piston stroke with respect to the predetermined by the crankshaft position sensor crankshaft phase angle or the phase angle of the crankshaft causes the actually aspirated fresh gas charge from the reference fresh gas charge deviates and thus not based on the reference data set control parameters are optimal. Also, a deviation of the current measured values for the respective pressure in the air intake tract and in the exhaust gas outlet tract leads to errors in the determination of the actually sucked fresh gas charge. Other sources of error which may have a negative effect on the operating behavior of the internal combustion engine are, for example, a different fuel composition, different trim of the intake tract or the exhaust tract, different fuel injection timing, different

Fuel injection quantities and possibly different compression ^¬ tion ratios. During operation of the internal combustion engine can result from these errors significant negative effects in terms of emissions, consumption, performance, smoothness, etc. Possible causes of the deviations described may be, for example:

- Manufacturing and / or assembly tolerances of the mechanical components involved, as well

- Wear in operation as well

- Deformation phenomena elastic or plastic by high mechanical stress states.

The previous solution of the problem described, according to the current state of the art, is in principle in the recurrent or continuous determination and quantification of the occurring deviations between the reference internal combustion engine and series internal combustion engine during operation to appropriate measures for correction or Compensation by adjustment of control parameters to perform.

To further increase the accuracy and, where appropriate, to plausi ^¬ bilisierung and monitoring the determination of the above deviations methods have been developed in the past, which operate independently of corresponding position and position sensors.

In the above-mentioned methods for recurring or continuous determination of said deviations, dynamic pressure oscillations assignable to the respective cylinder in the air intake tract or in the exhaust gas outlet tract of the relevant internal combustion engine are measured during operation and from this a corresponding pressure oscillation signal is generated. At the same time a crankshaft phase angle signal is ermit ^¬ telt.

The term "air-intake system" or simply "intake system", "induction" or "intake tract" a Ver ^¬ brennungsmotors the expert sums it together all the components that are used for air supply to the respective combustion chambers of the cylinders and thus define the so-called air path , These may include, for example, an air filter, an intake manifold, intake manifold or manifold or short intake manifold, a throttle valve, and possibly a compressor and the intake port ^¬ in the cylinder or the inlet channel of the cylinder belong.

By the term "exhaust gas exhaust tract" or simply "exhaust tract", "exhaust tract" or "exhaust system" on the other hand, all components are summarized over which the exhaust flows and thus form the so-called exhaust path, such as: The exhaust port or the exhaust port of each cylinder, exhaust pipes, exhaust gas recirculation components, particulate filters, catalytic converters and silencers. _

y

The phase and / or amplitude to be determined ^¬ least a selected frequency signal of the measured pressure oscillations with respect to the crankshaft phase angle signal using Discrete-Four- ier transformation from the pressure oscillation signal. Furthermore, based on the determined phase position and / or amplitude of at least one respective selected signal frequency, using current reference values or reference characteristic curves, the current values of said deviations are determined. For this purpose, the reference values or reference characteristic curves were previously determined on an ideal reference internal combustion engine of the same type and stored in corresponding characteristic diagrams or currently determined by means of a respective algebraic model function. On the basis of the ascertained deviations, corrections or adaptations of the control parameters of the internal combustion engine, depending on the deviations ascertained, may then be carried out in the control unit. Thus, for example, document DE 10 2015 209 665 A1 discloses a method for identifying valve control times of an internal combustion engine. In this case, the phase angle of selected signal frequencies of the measured pressure oscillations are above ^¬ be credited determined. On the basis of the determined phase angle, the valve control times of the relevant internal combustion engine are then determined using reference phase angles and associated reference valve control times of the same signal frequencies of the pressure oscillations of a reference internal combustion engine and / or a model function derived therefrom.

Another method for the combined identification of a piston stroke phase difference, an intake valve lift phase difference, and an exhaust valve lift phase difference Internal combustion engine is known from document DE 102015222408 B3. Here, too, the phase positions of selected signal frequencies of the measured pressure oscillations in the inlet and / or outlet tract, with respect to the crankshaft phase angle signal, are determined by means of discrete Fourier transformation. On this basis, depending on intake valve lift phase difference and exhaust valve lift phase difference lines of equal phase positions of the selected signal frequencies are determined and a common intersection of the determined lines determined by signal frequency-dependent phase shift.

From the determined common intersection, the intake valve lift phase difference and the exhaust valve lift phase difference are determined and the piston stroke phase difference is determined from the value of the phase shifts that have occurred.

Documents DE 10 2015 226 138 B3 and DE 10 2015 226 461 A1 each disclose a method for determining the composition of the fuel used for operating an internal combustion engine. These methods are based on the measurement and analysis of the pressure oscillations in the intake tract of the respective internal combustion engine by means of discrete Fourier transformation. In this case, for example, in addition to the determined

Actual phase position of the selected signal frequency at Saugsynchroner fuel injection, in the same way, without

Fuel injection or direct fuel injection into the closed combustion chamber, a further comparison phase position of the selected signal frequency and the actual phase position difference between the two determined. Then, by use of reference phase position differences of the same signal frequency for different fuel to ^¬ sammensetzungen, the fuel composition of the fuel actually used is determined. A method for determining the start of injection time and the injection quantity of the fuel in normal operation of an internal combustion engine, also based on measured

Pressure oscillations in the intake tract of the internal combustion engine is known from document DE 10 2015 226 461 A1.

Further methods based on the measurement of the dynamic pressure oscillations in the intake tract or exhaust tract and their analysis by means of discrete Fourier transformation, such as:

- the combined identification of phase differences of the intake valve and exhaust valve of Ver ^¬ brennungsmotors;

- the determination of the compression ratio of an internal combustion engine;

- The monitoring of deviations occurring in the valve train of an internal combustion engine and

the determination of the current trim of the intake tract of an internal combustion engine during operation,

are in the German patent applications with the file number

10 2016 219 584.0; 10 2017 209 112.6; 10 2016 222 533.2 and 10 2017 209386.2 disclosed.

In the application of the above-mentioned method can result in defective pressure vibration signals, for example, due to a defect or inadequate function of the pressure sensor, as a consequence, significant deterioration in performance and in particular in the exhaust performance of the internal combustion engine. For this reason, it is important and sometimes even required by law, to ensure the flawless, flawless function of such, the exhaust behavior influencing components over the entire operating life of the respective internal combustion engine or to detect malfunctions during operation. The present invention is therefore based on the object of providing a simple, cost-effective and reliable method by means of which a malfunction of a pressure sensor arranged in the air intake tract or exhaust gas outlet tract of a combustion engine, during operation, in particular with respect to its dynamic Behavior, reliable and timely can be determined.

This object is achieved by a method for checking the function of a pressure sensor in the air intake tract or exhaust gas outlet tract of an internal combustion engine in operation according to the main claim.

Embodiments and developments of the subject invention are the subject of the dependent claims.

According to the inventive method for checking the function of a pressure sensor in the air intake tract or Ab ^¬ gas outlet tract of an internal combustion engine during operation, the dynamic pressure oscillations of the intake air in

Air intake tract or the exhaust gas in the exhaust gas outlet tract of the relevant internal combustion engine measured during operation by means of the be ^¬ pressure sensor and from there generates a corresponding pressure oscillation signal. On the basis of this pressure oscillation signal Discrete-Fourier transform, a value of a specific operating Charakteristikums of Burn ^¬ voltage motors is formation using, for several selected signal frequencies determined. By comparing the values obtained with each of the determined deviation values for different signal frequencies values of Betriebscharakteris ^¬ tikums are then determined from each other. These deviation values are then used to evaluate the function of the respective pressure sensor, wherein the correct functioning of the pressure sensor is confirmed if none of the determined deviation values is exceeding a predetermined deviation threshold, and wherein diagnoses a malfunction of the pressure sensor when at least once exceeds at least one of the determined From ^¬ weichungswerte a predetermined deviation threshold.

The advantages of this process are that this pressure sensor can be checked without additional sensors, purely on the basis of Druckschwin ^¬ supply signal of the pressure sensor to be checked even that function. In addition, the measurements and analyzes of the pressure oscillation signal, which are executed repeatedly in operation anyway, can largely be resorted to, which ensures timely detection of a malfunction of the pressure sensor.

To analyze the pressure oscillation signal, this is subjected to a discrete Fourier transform (DFT). For this purpose, an algorithm known as Fast Fourier Transformation (FFT) can be used for the efficient calculation of the DFT. By means of DFT, the pressure oscillation signal is now decomposed into individual signal frequencies which, in the following, can be analyzed separately in terms of their amplitude and the phase position.

In the present case has been shown that malfunctioning of a pressure sensor, in particular in the measurement of hochdy ^¬ namic pressure oscillations, have different effects on different frequencies referred to as the signal frequency components of the pressure oscillation signal. Thus resulting in the determination of a particular Betriebscharakte- ristikums based on the pressure oscillation signal under strong ^¬ schiedliche values for different signal frequencies, it is assumed that a malfunction or at least an impairment of the proper functioning of the pressure sensor is present. This makes the method according to the invention Utilizing each of a current value of Betriebsscharakte- is for a plurality of different Signalfre ^¬ frequencies is determined and these values are compared with each other. This can be done for example by simple difference formation between two values. Only the highest value with the lowest value or each value with each other value can be compared. The difference values thus determined are generally referred to here as deviation values. The permissible maximum size of the deviation value is determined in advance, for example in the specification or a

Measurement of the respective sensor type, set a deviation limit. This deviation limit is in the used through ^¬ out the method for comparison with the determined deviation values, the proper functioning of the pressure sensor is asserted when none of the difference values calculated will exceed the predetermined deviation threshold, and on the other hand diagnoses a malfunction of the pressure ^¬ sensors if at least once, so at least ^¬ reaches the predetermined deviation limit in a measuring passage, at least one of ermit- telten deviation values or at least the largest deviate ^¬ deviation value or more.

A further embodiment of the method according to the invention makes use of the knowledge that malfunctions of a pressure sensor have a different effect both on the phase position and on the amplitude of the respective signal frequencies. This embodiment of the method is accordingly characterized ge ^¬ denotes that at the pressure oscillation signal, a crankshaft phase angle signal is determined simultaneously, and the phase position and / or the amplitude of the selected signal ^¬ frequencies of the measured pressure oscillations with respect to the crankshaft phase angle signal are determined and that based on the respectively determined phase position or amplitude or Phase position and amplitude of the respective signal frequency per value of a specific operating characteristic of the combus ^¬ tion motor is determined.

The crankshaft phase angle signal required for carrying out the method according to the invention can be determined by means of a toothed wheel connected to the crankshaft and a Hall sensor. Such a sensor arrangement is also already present in modern internal combustion engines for other purposes. The crankshaft phase angle signal generated thereby can be easily shared by the method according to the invention. This has the advantage that no additional sensor has to be arranged and thus no additional costs for carrying out the method according to the invention are caused. This embodiment is particularly advantageous if, in particular, the determination of the corresponding operating characteristic on the phase position or amplitude or phase position and amplitude of a respective signal frequency is determined.

In further embodiments of the method is the particular operating characteristic of the internal combustion engine one or more of the following operating parameters: an intake valve lift phase position, an exhaust valve phasing, a piston stroke phase position, a fuel composition, a Be ^¬ commencement timing of the fuel injection, Injection amount of the fuel injection, a compression ratio of the cylinder, a trim of the intake tract and a valve ^{¬ operation} deviation value. To determine these mentioned operating parameters based on the pressure oscillation signal determined in the air-intake tract or from ^¬-gas outlet zone is made here to the disclosure of the initially mentioned prior art documents in which the individual process will be explained in detail. When using a plurality of said operating parameters as an operating characteristic, for example, after determining a first deviation value of a specific first operating characteristic that exceeds the deviation limit value, a further deviation value can first be determined on the basis of another specific operating characteristic to confirm the first deviation value ,

The advantages of using the mentioned operating parameters as an operating characteristic are that these operating parameters are determined continuously during operation anyway and the additional effort for checking the function of the

Pressure sensor can thus be kept very low. In an advantageous manner, for carrying out the method according to the invention, the selected signal frequencies correspond to the intake frequency as fundamental frequency or first harmonic and the further multiple, that is to say the second to nth of the so-called

"Harmonic" of the intake frequency of the internal combustion engine.

The intake frequency is again in clear connection with the speed of the internal combustion engine.

For these selected signal frequencies then, for example, using a parallel recorded crankshaft phase angle signal, the phase position referred to in this context as the phase angle and the amplitude of the selected signal frequencies with respect to the crankshaft phase angle can be determined. This makes especially clear and thus well evaluated results are obtained when determining the respective specific operating Charakteristikums, whereby a high Ge ^¬ accuracy of the results can be secured forwards. Advantageously, the method, as well as the individual methods for determining the aforementioned operating parameters, on an electronic programmable engine control unit (CPU) of the respective internal combustion engine are executed. This has the advantage that no separate control or computing device is required and the algorithms of the method in the corresponding processes of the engine control programs, and in particular ^¬ special in the algorithms for determining the operating parameters can be integrated.

, Is in a further refinement of the embodiment previously described of the method according to the invention on an engine control unit if a malfunction of the pressure sensor is diagnosed continue to operate in an emergency ^¬ running mode by the engine control unit of the internal combustion engine or an emergency stop of the Ver ^¬ brennungsmotors initiated. Alternatively or additionally, an error message is output, for example, a

Driver signals that the pressure sensor has been detected as defective.

Thus, it is ensured in an advantageous manner that the respective internal combustion engine is not operated with erroneous control variables based on a faulty pressure oscillation signal of the corresponding pressure sensor which can not ensure compliance with the emission limits.

The motor control unit according to the invention for controlling an internal combustion engine, has at least one electronic processing unit, at least one electronic storage unit, a plurality of signal inputs and a plurality of signal outputs. Optionally, the electronic processing unit can also have a number of separate or combined computing units and memory units. In this case, in at least one of the electronic processing units and / or in the electronic memory unit , ₀

stored a program code and calculation parameters, for carrying out the previously described inventive method according to one of the described embodiments, by means of the motor control unit, during the normal operation of the internal combustion engine.

Advantage of the engine control unit according to the invention is that the program code and calculation parameters for performing the method according to the invention can be embedded directly into the routines and program sequences for controlling the operation of the internal combustion engine and that also no separate control units are required.

A detailed description of the method according to the invention is given below with the aid of the figures.

Show it:

FIG. 1: a simplified schematic drawing to explain the

Structure and the function of a reciprocating internal combustion engine.

FIG. 2 shows a simplified block diagram for illustrating an embodiment of the method according to the invention. FIG. 3 shows a further detail from the simplified block diagram according to FIG. 1 for a more detailed illustration of an embodiment of the method according to the invention.

Function and naming equal parts are indicated in the figures throughout with the same reference numerals.

The schematic drawing shown in Figure 1 to explain the structure and function of a reciprocating internal combustion engine has already been described in the introduction. It should be noted, however, that the illustrated motor control unit 50, at least one electronic computing unit 53, at least one electronic memory unit 54, a plurality of signal inputs 51 and a plurality Signal outputs 52, which can also be supplemented by power outputs has. Furthermore, a program code and calculation parameters are stored in the electronic processing unit 53 and / or in the electronic storage unit 54, by means of which the execution of the method according to the invention, as previously described, by means of the motor control unit 50, during normal operation of the internal combustion engine. FIG. 2 shows a simplified block diagram in which the essential method steps in the individual blocks are summarized.

At the beginning dynamic pressure oscillations of the intake air in the air intake tract 20 and / or of the exhaust gas in the exhaust gas outlet zone 30 of the respective internal combustion engine 1 by means of the Subject Author ^¬ fenden pressure sensor 44 are measured in operation and generates therefrom a corresponding pressure oscillation signal DS_S what indicated by the BL Block is shown.

In the block marked with D2 then takes place on the basis of the pressure oscillation signal DS_S, using Discrete-Four- ier transform DFT, the determination of the values of the out ^¬ searched operation Charakteristikums Emtlg_BChk_Wl ... X held, as represented by block B2. It is based on the

Pressure vibration signal DS_S using Discrete Fourier transform DFT, for several selected signal frequencies SF1, SF2 to SFX (also SF1 ... X) each have a value of the specific operating characteristics BChk_Wl, BChk_W2 to BChk_WX (also BChk_Wl ... X) of the internal combustion engine 1 determined. The individual determined values of the operating characteristic, BChk_Wl, BChk_W2 to BChk_WX, are represented in FIG. 2 by the blocks B3.1, B3.2 to B3.X. One or more operating parameters which are determined on the basis of the same pressure oscillation signal DS_S can be used as a specific operating characteristic, according to one of the methods of the prior art mentioned in the introduction. Thus, for example, an intake valve ^¬ stroke phase position, an exhaust valve lift phase position or a piston stroke phase position can be used as a specific operating characteristics, which can be determined for example with one of the disclosed in the prior art method. Also, a fuel composition, a start time of the force ^¬ fuel injection, an injection quantity of fuel injection, a compression ratio of the cylinders, a trim of the inlet tract and valve train deviation value, determined according to the methods disclosed in the input patent documents mentioned, can be used as a specific operating characteristic.

For example, if more of the above Betriebspa ^¬ parameters from the pressure oscillation signal DS_S of the to be tested pressure sensor determined 44, so it is advisable to carry out the OF INVENTION ^¬ dung modern methods based on these multiple Betriebspa ^¬ parameters as a respective operating characteristic and the results for the verification or confirmation of the individual result. For example, misjudgments due to so-called outlier measurements can be avoided.

In the further course of the method according to the invention, the determination of so-called deviation values now takes place

Emtlg_Aw_Wl ... Y of the values of the operating characteristic BChk_Wl ... X determined for different signal frequencies SF1 ... X from each other, which is symbolized by block B4. This may for example, by comparison, especially Diffe ^¬ ence education of any two determined values. It can For example, first the most distant values are determined and the difference between these two values is formed. Whereby a maximum deviation value is found. Or, all determined values of the operating characteristic BChk_Wl ... X are compared with all other values of the operating characteristic, resulting in several deviation values Aw_Wl, Aw_W2 to Aw_WY (also Aw_Wl ... Y), which in FIG. 1, B4.2bisB4.Y blocks is shown.

In the further course of the method according to the invention, a respective comparison of the determined deviation values Aw_Wl, Aw_W2 to Aw_WX with a predefined deviation limit value Aw_Gw takes place as to whether at least one of the determined deviation values Aw_Wl, Aw_W2 to Aw_WX reaches the deviation limit value Aw_Gw or exceeds Aw_Wl ... X> Aw_Gw. This is illustrated in block B5.

The deviation limit Aw_Gw was to play determined in advance of the loading humor normal operation of the engine 1 at ^¬ empirically or by calculation and in which, in Figure 2 illustrated storage unit 54 of the electronic engine control unit 50 (CPU) deposited. On the same motor control unit 50, the inventive method can also be performed, which is stored there in the form of program code.

Based on the result of the above comparison Aw_Wl ... X> Aw_Gw, the correct function of the pressure sensor 44, DSens = ok, is confirmed as shown in block B6 if none of the detected deviation values Aw_Wl ... Y is a predetermined deviation limit value Aw_Gw reaches or exceeds. In contrast, a malfunction DSens_Ffkt of the pressure sensor (44) is diagnosed, as shown in block B7, if at least once at least one of the determined deviation values Aw_Wl ... Y reaches or exceeds a predetermined deviation limit value Aw_Gw.

In continuation of the method according to the invention can then, if a malfunction DSens_Ffkt the pressure sensor 44 di ^¬ agnostiziert, by means of the engine control unit 50, the internal combustion engine 1 in a runflat mode Nt-Btb reversed ^¬ switches and continue to operate as in block B8 .1, or an emergency stop of the internal combustion engine 1, Nt_stop, can be initiated, as shown in block B8.2. Likewise, alternatively or in addition to an error message (Info_Sig) is output, as shown by block B8.3, for example, a vehicle driver signa ^¬ lisiert that the pressure sensor has been detected as defective.

FIG. 3 shows a further detail of the simplified block diagram according to FIG. 1 for a more detailed illustration of an embodiment of the method according to the invention. In this case, it is shown by means of the block B1 .1 that a crankshaft phase angle signal Kw_Pw is determined simultaneously with the pressure oscillation signal DS-S. This is done, for example, by means of a crankshaft position sensor 41 provided anyway on the internal combustion engine, as shown in FIG.

Furthermore, the block B2 is further detailed in FIG. 3 in order to represent by the blocks B2.1, B2.2 to B2.X that for the selected signal frequencies SF1, SF2 to SFX (also SF1... X) of the measured pressure oscillation signal DS_S in each case the phase position Phil, Phl2 to PhlX (also Phll ... X) and / or the amplitude Ampi, Amp2 to AmpX (also Ampl ... X) of the selected signal frequencies SF1 ... X are determined with respect to the crankshaft phase angle signal Kw_Pw_S. Based on the respectively determined phase position Phll ... X or Amplitude Ampl ... X or phase position Phll ... X and Amplitude Ampl ... X, the respective value of a specific operating characteristic BChk_Wl ... X of the internal combustion engine 1 for the respective signal frequency SF1 ... X is determined.

Summarized briefly in the following, the invention relates to a method for checking the function of a pressure sensor in the air intake tract or exhaust outlet tract of a combustion ^¬ engine during operation and a motor control unit for performing the method and is based on that dynamic pressure oscillations of the intake air in the air -Ansaugtrakt or the exhaust gas in the exhaust gas outlet tract of the relevant internal combustion engine in operation by means of the respective pressure sensor are measured, and based on the pressure oscillation signal obtained using discrete Fourier transform for a plurality of selected signal frequencies each have a value of a specific operating characteristic of the internal combustion engine and deviation values of the values determined for the different signal frequencies are determined from each other. Depending on whether deviation values determined fall below or exceed a predefined limit value, the proper functioning of the

Pressure sensor confirmed or diagnosed a malfunction of the pressure sensor.

This makes it possible to monitor proper functioning of the pressure sensor ^¬ and to initiate appropriate action in case of failure, which is a malfunction of the engine and possibly based on increased

Prevent pollutant emissions.

Claims

claims

1. A method for checking the function of a pressure sensor (44) in the air intake tract (20) or exhaust gas outlet tract (30) of an internal combustion engine (1) in operation, wherein

- dynamic pressure oscillations of the intake air in the

Air intake tract (20) or the exhaust gas in the exhaust gas outlet tract (30) of the respective internal combustion engine (1) are measured during operation by means of the respective pressure sensor (44) and from a corresponding pressure vibration signal (DS_S) is generated; and

- Based on the pressure oscillation signal (DS_S) using discrete Fourier transform (DFT), for several selected signal frequencies (SF1 ... X) each have a value of a certain operating characteristic (BChk_Wl ... X) of Ver ^¬ combustion engine (1) is determined and deviation values (Aw_Wl ... Y) of the values of the operating characteristic (BChk_Wl ... X) determined for different signal frequencies (SF1... X) are determined from one another;

- Wherein the proper function of the pressure sensor (44) is confirmed (DSens = ok), if none of the determined deviation values (Aw_Wl ... Y) reaches or exceeds a predetermined deviation limit value (Aw_Gw) and

- wherein a malfunction (DSens_Ffkt) of the pressure sensor (44) is diagnosed if at least once at least one of the determined deviation values (Aw_Wl ... Y) reaches or exceeds a predetermined deviation limit value (Aw_Gw).

2. The method according to claim 1, characterized in that simultaneously with the pressure oscillation signal (DS-S) a crankshaft phase angle signal (Kw_Pw) is determined and the phase position and / or the amplitude of the selected signal frequencies ^¬ (SF1 ... X ) of the measured pressure vibration signal (DS_S) with respect to the crankshaft phase angle signal (Kw_Pw_S) are determined and that

is determined on the basis of the respectively determined phase position or amplitude or phase position and amplitude of each one value of a specific operating characteristic (BChk_Wl ... X) of the internal combustion engine (1).

3. The method of claim 1 or 2, characterized in that the particular Betriebscharakteristikum of the internal combustion engine one or more of the operating parameters: an inlet valve lift phase position, an exhaust valve ^¬ stroke phase position, a piston stroke phase position, a fuel ^¬ composition, a beginning Time of fuel injection, an injection amount of Kraftstoffein ^¬ tion, a compression ratio of the cylinder, a trim of the intake tract and a valve train deviation value, is / are.

4. The method according to any one of claims 1 to 3, characterized in that the selected signal frequencies (SF1 ... X) the intake frequency and at least one further multiple of the

Intake frequency of the internal combustion engine (1) are.

5. The method according to any one of claims 1 to 4, characterized in that the method is carried out on an electronic programmable engine control unit (50) of the subject ^¬ fenden internal combustion engine (1).

6. The method according to claim 5, characterized in that, if a malfunction (DSens_Ffkt) of the pressure sensor (44) is diagnosed by means of the engine control unit (50) of

Internal combustion engine (1) in a limp home mode (Nt-Btb) continues to operate or an emergency stop of the internal combustion engine (1) (Nt stop) is initiated, wherein alternately or In addition to each an error message (Info_Sig) is issued.

7. Motor control unit (50) for controlling a combustion engine (1), the at least one electronic Re ^¬ cheneinheit (53), at least one electronic memory ^¬ unit (54), a plurality of signal inputs (51) and a plurality Sig ^¬ nalausgänge ( 52), wherein in the electronic Re ^¬ cheneinheit (53) and / or in the electronic memory unit (54) a program code and calculation parameters are stored for carrying out the method according to one of claims 1 to 4 or 6 by means of the motor control unit (50), during the intended operation of the Burn ^¬ voltage motors.