EP1989424A2

EP1989424A2 - Engine control and method for determining the pressure in a combustion chamber of an internal combustion engine

Info

Publication number: EP1989424A2
Application number: EP07704644A
Authority: EP
Inventors: Gianluca Caretta
Original assignee: Siemens AG
Current assignee: Continental Automotive GmbH
Priority date: 2006-02-21
Filing date: 2007-02-19
Publication date: 2008-11-12
Also published as: US7962273B2; CN101389843B; WO2007096331A2; WO2007096331A3; CN101389843A; DE102006008062B3; US20090024298A1

Abstract

The invention relates to an engine control for an internal combustion engine (1) and to a method whereby a pressure signal (pA) reproducing the pressure (pA) in one of the combustion chambers (2A) is supplied to an evaluation unit (5) by means of a pressure signal sensor (4). According to the invention, the evaluation unit (5) uses the pressure signal (pA) to determine the pressure (pB, pC, pD) in at least one other combustion chamber (2B, 2C, 2D).

Description

description

Engine control and method for determining the pressure in a combustion chamber of an internal combustion engine

The invention relates to an engine control system and a method for determining the pressure in a combustion chamber of an internal combustion engine according to the preambles of claim 1 and the independent claims.

For better combustion of the introduced into a combustion chamber of an internal combustion engine, numerous devices and methods have been proposed in recent years, with which a more environmentally friendly combustion of the mixture is made possible. It is known to measure the pressure in one or more of the combustion chambers. The measurement of the pressure in a combustion chamber offers the advantage that the heat released during a combustion process can be calculated in the combustion chamber in order to improve subsequent combustion processes by changing injection parameters.

Since the injection conditions, such as Geometry ^¬ rie of the injectors, can combustion engine change over the lifetime of the fuel, it is advantageous if the pressure in the ^¬ sem combustion chamber is known for each of the combustion chambers of the time course to the combustion process indivi ^¬ Duel to optimize. However, measuring the pressure in each of the combustion chambers, for example with a pressure sensor built into the spark plug, has the disadvantage that it is costly since a pressure sensor must be provided for each of the combustion chambers. Furthermore, it is disadvantageous that each of these pressure sensors must be connected to the motor controller evaluating the pressure signals.

It is therefore the object of the invention to remedy the disadvantages of the prior art and in particular to provide a device specify a method and with which the pressure in multiple combustion chambers can be determined easier or cheaper.

The object is achieved with a motor control according to claim 1 and a use of the motor control and a method according to the independent claims.

The invention is based on the recognition that, depending on the pressure signal which represents the combustion chamber pressure in one of the combustion chambers, the combustion chamber pressure can be determined in at least one further combustion chamber, for example by extrapolation. Thus, the simplest assumption is that the combustion chamber pressure in the further combustion chamber is only offset in time from the combustion chamber pressure in the combustion chamber for which the pressure signal was determined. The time offset resul ^¬ advantage of the delayed clock expiry of Verbrennungspro ^¬ processes in the various combustion chambers of an internal combustion engine, such as a four-stroke internal combustion engine. In an internal combustion engine with a large number of cylinders, for example eight, ten or twelve, it is also mög ^¬ Lich that a plurality of combustion chambers with respect clocked the Verbrennungspro ^¬ zesses synchronously so that no time shift in the calculation of the combustion chamber pressure in said further fuel is to be considered.

It is particularly advantageous if the combustion chamber pressure in the at least one further combustion chamber is determined as a function of the pressure signal and a further parameter of the internal combustion engine. The other parameters can ^¬ example, be a temperature measured on the engine temperature such as the oil temperature.

Preferably, the motor control according to the invention at least one pressure signal input for receiving at least ei ^¬ nes pressure signal, wherein the number of Drucksignaleingän ge ^¬ is smaller than the number of combustion chambers of the Brennkraft- machine. Particularly preferred is exactly one Drucksignalein ^¬ gear, optionally a pressure signal input per cylinder bank. With pressure signal input in this application, an actually located at the engine control input is referred to or an existing line for supplying a pressure signal to the engine control. For example, it is also possible for the engine controller to have a number of pressure signal inputs which is equal to or greater than the number of combustion chambers of the internal combustion engine, but not all of these pressure signal inputs physically present on the engine control system are occupied. It is also conceivable that the pressure signal inputs are present only virtually, for example if the motor controller has a serial interface at which the pressure signals or the pressure signal are serially clocked and digitally fed.

Advantageously, the engine control system has a pressure sensor which measures the combustion chamber pressure in the one combustion chamber and which is connected to the pressure signal input for feeding in the pressure signal. The pressure sensor may be, for example, a pressure sensor arranged in the spark plug, which measures the combustion chamber pressure in the combustion chamber directly. Another possibility is that the pressure sensor indirectly measures the combustion chamber pressure in the combustion chamber, for example by measuring material deformations of the material enclosing the combustion chamber.

Preferably, the engine controller has one or more pressure sensors, wherein the number of pressure sensors is smaller than the number of combustion chambers of the internal combustion engine. Be ^¬ particularly preferred exactly one pressure sensor, optionally a pressure sensor per cylinder bank. This offers the particular advantage that the equipment of the internal combustion engine with pressure sensors is cost-effective, since not every combustion chamber has to be equipped with a pressure sensor. In the context of the invention, however, it is also possible to equip all combustion chambers of the internal combustion engine with a pressure sensor and the To use invention to detect faulty signals of one or more pressure sensors by a plausibility check.

Is the method, advantageously the number of indications ^¬ recessed pressure signals is smaller than the number of combustion chambers of the internal combustion engine. Furthermore, the number of combustion chambers whose combustion chamber pressure is measured to determine the pressure signals is preferably smaller than the number of combustion chambers of the internal combustion engine.

Advantageously, a speed signal is recorded within the scope of the invention, which reproduces a speed of the internal combustion engine. The speed is preferably forward speed a rotational speed or a Drehwinkelge ^¬. For the reception of the speed signal, the motor controller advantageously has a speed signal input. The evaluation unit of the internal combustion engine then determines the combustion chamber pressure in the further combustion chamber as a function of the speed signal and of the pressure signal. It is possible other parameters of the engine into account in addition to these two parameters to be ^¬. The speed signal can, for example, reproduce the rotational angular speed of the crankshaft of the internal combustion engine. The consideration of the VELOCITY ^¬ keitssignals is advantageous, as by a combustion process in one of the combustion chambers, the crankshaft speed or a different speed is influenced of the engine loading. Thus, when a mixture is burned in a combustion chamber, the crankshaft is generally accelerated. In the context of the invention it is advantageous if a correlation between the speed signal and the pressure signal is derived, so that a is changed ^¬-reducing rate signal on the combustion chamber pressure, that is also the pressure characteristic, can be closed. Thus, for example, in the case of a sharp increase in the speed of the internal combustion engine, it can be assumed that a Combustion with a high pressure has taken place, which has led to a large force on the reciprocating piston of the affected combustion chamber. It is advantageous in particular accordingly insbeson ^¬ when a Korrelati ^¬ on is created from the pressure signal of a combustion space and the speed signal of the engine to close a ge at a different time ^¬ measured speed signal to a pressure variation in ei ^¬ nem combustion chamber in which a combustion process takes place.

Advantageously, a correction device is provided which changes the speed signal corrected, the one to be the internal combustion engine is closed ^¬ drive train caused by vibrations. So it should be noted that the internal combustion engine drive train by the on ^¬ mechanical boundary conditions is exposed to which the speed of the internal combustion engine beeinflus ^¬ sen. Thus, the increase in the speed of Brennkraftma ^¬ machine is lower, if the engine has to drive a load, in the rule assumed here, this is me ^¬ chanically coupled to the ground drive axle of the ^¬ drivetrain of a motor vehicle. Particularly problematic are vibrations of the drive train, which can arise due to the Elas ^¬ ticity of the drive train and thus can cause a mechanically externally imprinted acceleration of the crankshaft speed of the internal combustion engine. In the context of modern engine control systems it is possible to detect such oscillations to occur, for example, by the speed of the connected to the crankshaft waste drive shaft of the internal combustion engine is detected by game, every 0.5 degrees, a timing signal is generated at ^¬. The rate of cure can ^¬ belwelle or the output shaft or the drive train are very accurately detected by comparing the time signals so that these influences on the overall schwindigkeitssignal can be taken into account to correct schwindigkeitssignal to the Ge ^¬. Advantageously, a connection or a Korrelati ^¬ on between the speed signal and the pressure signal is determined, this relationship is advantageously abge ^¬ stores. For this purpose, a memory is advantageously provided, in which also or alternatively the pressure signal or the speed signal can be stored. Upon detection of the connection, it is particularly advantageous if the connection is via a plurality of combustion processes it ^¬ averages, so that measurement inaccuracies play a smaller ROI Ie or a multi-dimensional map is generated in which various multiple Geschwindigkeitssignalverläu ^¬ fe different pressure waveforms are stored, which are advantageously occupied with parameters, so that they can be adapted to the measured values.

Advantageously, the combustion chamber pressure in the further combustion chamber is dependent on the stored pressure signal or the stored speed signal or the stored relationship, i. optionally determined as a function of a stored characteristic map.

Another independent object of the invention is an internal combustion engine with an advantageous engine control with the above features.

The use of a motor controller having the above features is also an independent object of the invention.

A method for determining a pressure prevailing in a combustion chamber of the combustion chamber pressure provides a further independent aspect of the invention, wherein in the above Be ^¬ scription is referenced by process features.

The invention will be explained in more detail below with reference to the accompanying drawings, wherein the drawings and the following the following description only exemplary Ausführungsbei ^¬ games of the invention play.

FIG. 1 shows an engine control according to the invention for an internal combustion engine.

FIG. 2A shows a method according to the invention for creating a characteristic map.

Figure 2B shows graphs of parameters of the internal combustion ^¬ machine in connection with the method of Figure 2A.

FIG. 3A shows a method according to the invention for determining a combustion chamber pressure in a further combustion chamber.

FIG. 3B shows diagrams with parameters associated with the method of FIG. 3A.

FIG. 1 shows an internal combustion engine 1 with four combustion ^chambers 2A, 2B, 2C and 2D, each combustion chamber 2A, 2B, 2C and 2D each having a spark plug 3A, 3B, 3C and 3D. The spark plug of the combustion chamber 2A 3A is equipped with a pressure sensor 4 that measures the combustion chamber pressure p _A in the combustion chamber 2A. The pressure sensor 4 outputs a pressure signal reproducing the combustion chamber pressure p _A to an evaluation unit 5. The evaluation unit 5 is connected to a memory 6 verbun ^¬ the, in which the evaluation unit 5 different characteristics and data, such as the combustion chamber pressure p _A or a map, can save and can call from there again.

The exemplary embodiment of the engine control according to the invention of FIG. 1 furthermore comprises a rotational angle sensor 7 which determines the rotational angle CRK of the crankshaft 8 of the internal combustion engine 1. Specifically, when the crankshaft 8 is rotated by 0.5 °, the rotation angle sensor 7 outputs a signal. This is Sig nal ^¬ firstly directly to the evaluation unit 5 available and also fed into a correction unit 9. The correction unit 9 serves to eliminate vibrations existing on the mechanical load side of the internal combustion engine 1 from the speed signal which is detected by the rotation angle sensor 7 and which represents the rotational angular velocity of the crankshaft 8. For this purpose, the correction unit 9 has a further signal input 10, via which the correction unit 9 receives at least one further win ^¬ kellage another part of the connected to the internal combustion engine 1 and the crankshaft 8 drive train. This is advantageously the angular position of one or several ^¬ rer driven wheels of a vehicle which is driven by the internal combustion engine. 1 The correction of the signal output from the rotation angle sensor signal 7 can also be made or additionally by evaluation of a torsion signal that the torsion dergibt a part of the drive train as ^¬. Thus, preferably, the torsion of a part of the on ^¬ drive train or of the output-side part of the crankshaft are measured strip 8 with a magnetostrictive sensor or a measurement. In this manner, it is advantageous ^¬ legally possible, a fictitious load independent VELOCITY ^¬ keitsgröße the internal combustion engine to charge 1 which dergibt an increase in the rotational angular velocity of the crankshaft 8 as ^¬ that would occur without the load. Furthermore, the correction unit 9 and the evaluation unit 5 with a

Time signal t supplied to the above speeds and changes can be calculated. The correction unit 9 outputs a corrected rotational angular velocity dCRK / dt to the evaluation unit 5, this corrected rotational angular velocity preferably being the above-mentioned notional rotational angular velocity increase of the internal combustion engine 1 without load.

The evaluation unit 11 also has a signal output at which calculated combustion chamber pressures p _A , p _B , P _c and p _D are output for all combustion chambers 2A, 2B, 2C and 2D. In Figures 2A and 2B, a method and explanatory diagrams shown, the method with the OF INVENTION ^¬ to the invention embodiment of Figure 1 can be performed. Therefore, in the following description of Figures 2A and 2B reference is made to the description of Figure 1. The method of Figure 2A is used to determine a map of the ten for various Drehwinkelgeschwindigkei ^¬ dCRK / dt and different angular positions of the crankshaft CRK 8 of the internal combustion engine 1, a pressure curve p _A, P _B? P _C or p _{D can be taken} for the combustion chamber 2A, 2B, 2C or 2D, in which a combustion process is taking place. He ^¬ for mediation of this map is repeated through a loop, wherein the first step of this loop is that the combustion chamber pressure p _A in the combustion chamber 2A measured.

Subsequently, the rotational angle position of the crankshaft CRK is 8 ^¬ it averages and from this size is again the Drehwinkelge ^¬ speed dCRK / dt of the crankshaft 8 is calculated and corrected in the manner described above. The sizes thus determined are incorporated into the map, with statistical Me ^¬ methods are used to interpolate the characteristic field and smooth. Subsequently, a query is made whether the map is sufficiently densely populated with data. If so, the procedure ends. If there are not enough data for a sufficiently dense population of the characteristic map, the method jumps back to the first step, in which again the combustion chamber pressure p _{A is} measured in the combustion chamber 2A.

FIG. 2B shows various relationships between the rotational angular velocity dCRK / dt and the combustion chamber pressure p _A measured in the combustion chamber 2A. The diagrams shown in the Figure 2B two contain two variables mentioned in each case via the crankshaft rotational angle CRK plotted gene. There are illustrated three curves, the weils each represent ^¬ a combustion stroke with (curves 2 and 3) and without (curve 1) combustion , At the spa venverlauf 1 without combustion the Drehwinkelge ^¬ speed dCRK / dt does not change. In contrast, with the combustion taking place, the rotational angular velocity dCRK / dt is changed under the influence of the combustion, the change of this magnitude being accompanied by the combustion chamber pressure p _A developing in the combustion chamber 2A. At a higher combustion chamber pressure p _A , the rotational angular velocity dCRK / dt is correspondingly changed more strongly, ie the crankshaft 8 is accelerated more strongly. In the above-mentioned map now different for different angular positions CRK correlations are p between the combustion chamber pressure _A in the combustion chamber 2A and the increase of the rotation angular velocity dCRK / dt stores abge ^¬.

FIGS. 3A and 3B illustrate a method and diagrams used in the method. The method of FIG. 3A uses the map determined using the method of FIG. 2A to determine the combustion chamber pressure p _B , p _c or p _D in another of the combustion chambers 2B, 2C or 2D, in this case the combustion chamber 2B by way of example. In the same way as shown here, the combustion chamber pressures p _c and p _D in the combustion chambers 2C and 2D can be determined. The method illustrated in Figure 3A is suitable to advertising performed by the embodiment illustrated in the figure 1 the evaluation unit 5, so that the description of figure 1 and on the loading ^¬ scription of Figures 2A and 2B is taken.

First, in the method of FIG. 3A, with which the pressure profile in the combustion chamber 2B is to be determined during a combustion process taking place there, the angle of rotation CRK and the rotational angular velocity dCRK / dt are calculated, said speed again being corrected in the manner described above becomes. The angle of rotation CRK is shifted by a predetermined angle, for example 180 °, wherein the angle by which the angle of rotation CRK is shifted, is dependent on the clock sequence of the internal combustion engine 1 ^¬ . This serves to reduce the considered combustion run in the combustion chamber 2B in the temporal sequence, ie with respect to the angle of rotation CRK to normalize. Dt is surrounded with the verscho ^¬ or normalized rotation angle CRK and Drehwinkelge ^¬ speed dCRK / from the above determined by the process of Figure 2A of characteristics of the combustion chamber pressure p _B in the combustion chamber 2B determined, wherein the magnitudes are terpoliert in the map in ^¬ if no measured value is available at the point concerned. Subsequently, a query is made whether the combustion cycle is completed in the observed combustion chamber 2B. If the combustion cycle is completed, the process is terminated and the pressure curve p _{B is} output via the output 11 of the evaluation unit 5.

The invention is not limited to the preferred embodiment described above. In particular, the illustrated method can also be performed with internal combustion engines with more than four combustion chambers or with less than four combustion chambers, it being also conceivable that, for example, provided in an internal combustion engine with ten or twelve combustion chambers with two cylinder banks each exactly a combustion chamber of a cylinder bank with a pressure sensor is. Furthermore, it is possible that more combustion chambers of an internal combustion engine are equipped with pressure sensors to improve the determination of the map. In addition, a large number of variants and modifications are possible, which also make use of the concept of the invention and therefore fall within the scope of protection.

Claims

claims

1. Engine control for an internal combustion engine (1) with meh ^¬ reren combustion chambers (2A, 2B, 2C, 2D) with - at least one pressure signal input for receiving mindes ^¬ least a pressure signal (p _A ), the combustion chamber pressure (p _A ) in one of Combustion chambers (2A), characterized by

- An evaluation unit (5), in dependence on the pressure signal (p _A ), the combustion chamber pressure (P _B , P _c , P _D ) in mind least ^¬ a further combustion chamber (2B, 2C, 2D) determined.

2. Motor controller according to claim 1, d a d u r c h e c e n e c e s in that the number of pressure signal inputs is smaller than that

Number of combustion chambers (2A, 2B, 2C, 2D) of the internal combustion engine (D •

3. Motor controller according to claim 1 or 2, characterized by a pressure sensor (4) which measures the combustion chamber pressure (p _A ) in the one combustion chamber and which is connected to the pressure signal input for feeding the pressure signal (p _A ).

4. Engine control according to one of the preceding claims, characterized by one or more pressure sensors (4), each of the combustion chamber pressure (p _A ) in one of the combustion chambers (2A) and are each connected to one of the pressure signal inputs, wherein the number of pressure sensors (4) is smaller than the number of combustion chambers (2A, 2B, 2C, 2D) of the internal combustion engine (D •

5. Motor controller according to one of the preceding claims, characterized by a speed signal input for receiving a speed signal (dCRK / dt), which has a speed of rotation speed (dCRK / dt) of the internal combustion engine (1), where ^¬ in the evaluation unit (5) the combustion chamber pressure (p _B , Pc, P _D ) in the further combustion chamber (2B, 2C, 2D) in response to the speed signal (dCRK / dt) determined.

6. The motor controller according to claim 5, which are caused by vibrations of a connected to the internal combustion engine (1) drive train ^¬ characterized by correction means (9), which corrects the speed signal (dCRK / dt) to change.

7. Motor controller according to claim 5 or 6, characterized in that the evaluation unit (5) is adapted to determine a relationship between ^¬ the speed signal (dCRK / dt) and the pressure signal (p _A ), wherein the evaluation unit (5) the Combustion chamber pressure (p _B , P _c , P _D ) determined in the at least one further combustion chamber (2B, 2C, 2D) depending on the context.

8. Motor control according to one of the preceding claims, characterized by a with the pressure signal input and / or the speed signal input and / or the evaluation unit (5) connected memory (6) for storing the pressure signal (p _A ) and / or the speed signal (dCRK / dt) and / or the context.

9. Motor controller according to claim 8, characterized in that the evaluation unit (5) the combustion chamber pressure (P _B , P _C , P _D ) in the further combustion chamber (2B, 2C, 2D) in response to the stored pressure signal (p _A ) and / / or the stored speed signal (dCRK / dt) and / or the stored context.

10. Internal combustion engine with a motor controller according to one of claims 1 to 9.

11. Use of a motor controller according to one of claims 1 to 9 for determining a combustion chamber pressure (p _A , P _B? P _er

12. Method for determining the pressure of a combustion chamber pressure prevailing in a combustion space (2A, 2B, 2C, 2D) (p _A , P _B, P _O P _D ) for an internal combustion engine (1) having a plurality of combustion chambers (2A, 2B, 2C, 2D) comprising the steps of: - recording at least one pressure signal (p _A ) containing the

Combustion chamber pressure (p _A ) in one of the combustion chambers (2A), characterized by

- Determining the combustion chamber pressure (p _B , Per P _D ) in at least one further combustion chamber (2B, 2C, 2D) in response to the pressure signal (p _A ).

13. The method according to claim 12, characterized in that the number of recorded pressure signals (p _A ) is smaller than the number of combustion chambers (2A, 2B, 2C, 2D) of the internal combustion engine (1).

14. The method according to any one of claims 12 or 13, characterized in that the pressure signal (p _A ) by measuring the combustion chamber pressure (P _A ) in one of the combustion chambers (2A) is determined.

15. The method according to any one of claims 12 to 14, characterized in that the number of combustion chambers (2A) whose combustion chamber pressure (P _A ) is measured, is smaller than the number of combustion chambers (2A, 2B, 2C, 2D) of the internal combustion engine ( 1) .

16. The method according to any one of claims 12 to 15, e e c e n e c e n e d d e r c h

Recording a speed signal (dCRK / dt) representing the rotational speed (dCRK / dt) of the internal combustion engine (1), and

- Determining the combustion chamber pressure (p _B , Per P _D ) in the further combustion chamber (2B, 2C, 2D) in response to the speed signal (dCRK / dt).

17. The method of claim 16, g e n e c e c e n e d d e r c h

- Determining changes in the speed signal

(dCRK / dt), the Doomed by a vibration of a combustion engine to the firing (1) connected to the drive train ^¬ be gently, and

Correcting the speed signal (dCRK / dt) for the vibration-related changes.

18. The method according to claim 16 or 17, e e c e n e c e n e d e r c h

- Determining a relationship between the pressure signal

(P _A ) and the speed signal (dCRK / dt) and

- Determining the combustion chamber pressure (p _B , Pc / - P _D ) in the further combustion chamber (2B, 2C, 2D) depending on the context.

19. The method according to any one of claims 12 to 18, g e c e n e c e n e t d u r c h

- Store the pressure signal (p _A ) and / or

- storing the speed signal (dCRK / dt) and / or - saving the relationship.

20. The method of claim 19, wherein:

- Determining the combustion chamber pressure (p _B , Per P _D ) in the further combustion chamber (2B, 2C, 2D) in dependence on the stored pressure signal (p _A ) and / or

- Determining the combustion chamber pressure (P _B , Pc / - P _D ) in the further combustion chamber (2B, 2C, 2D) in dependence on the stored speed signal (dCRK / dt) and / or - determining the combustion chamber pressure (p _B , Per P _D ) in the further combustion chamber (2B, 2C, 2D) in dependence on the stored relationship.