Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D35/00—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
  • F02D35/02—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions
  • F02D35/023—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions by determining the cylinder pressure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/18—Circuit arrangements for generating control signals by measuring intake air flow
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D2200/00—Input parameters for engine control
  • F02D2200/02—Input parameters for engine control the parameters being related to the engine
  • F02D2200/04—Engine intake system parameters
  • F02D2200/0402—Engine intake system parameters the parameter being determined by using a model of the engine intake or its components
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D2250/00—Engine control related to specific problems or objectives
  • F02D2250/14—Timing of measurement, e.g. synchronisation of measurements to the engine cycle

Definitions

• the present invention relates to the field of determining the mass of gas enclosed in a combustion chamber of an internal combustion engine.
• the mass of gas locked in a combustion chamber is a useful parameter in particular for the control of internal combustion engines, for the tests of internal combustion engines, in order in particular to analyze the combustion, to improve the strategies of control of the combustion. combustion, improve cycle-to-cycle and between-cylinder behavior of an internal combustion engine. Knowledge of this parameter is important in particular for spark ignition engines and for diesel engines equipped with exhaust gas recirculation (EGR) and / or variable timing.
• EGR exhaust gas recirculation
• some methods are based on measurements of the inlet pressure, which may not reliably represent the physical phenomena involved in the combustion chamber.
• Other methods require signal processing techniques which can be complex, time consuming, and which can also generate inaccuracies in the estimated trapped mass of gas.
• Patent application WO 2007060349 describes a method based on the use of a pressure sensor in the cylinder and a temperature sensor downstream of the exhaust valve. Thus, this method requires specific instrumentation of the internal combustion engine. In addition, this method reconstructs the temperature of the gas in the cylinder from the measurement of the temperature sensor downstream of the exhaust valve. This reconstruction generates approximations, which influence the accuracy of the estimated trapped gas mass.
• Patent application WO 2015082731 describes a method based on estimating the resonant frequency of the pressure in the combustion chamber by means of a Fourier transform, which is a processing of the signal coming from the pressure sensor. This estimate of the resonant frequency lacks precision for an accurate estimate of the mass of gas trapped.
• this method uses the solution of Bessel's equations, assuming that the combustion chamber is a perfect cylinder.
• the combustion chambers of internal combustion engines are not purely cylindrical. The estimate obtained by this method is therefore found to be erroneous because of this assumption.
• this method requires large amplitude oscillations.
• the object of the present invention is to accurately determine the mass of gas enclosed in a combustion chamber of an internal combustion engine, with simple and conventional instrumentation, and without complex signal processing.
• the method for determining the mass of gas enclosed in a combustion chamber according to the invention is based solely on measuring the pressure within the combustion chamber.
• the method uses a model of the combustion chamber, one of whose parameters, the frequency of pressure oscillations, is determined by measuring the gas pressure in the combustion chamber.
• the method according to the invention is precise, reliable, and requires simple instrumentation.
• said volume V of said combustion chamber is obtained by means of a mapping as a function of the crankshaft angle of said internal combustion engine.
• said wavelength l is obtained by means of a mapping as a function of the crankshaft angle of said internal combustion engine.
• said mapping of said wavelength l is constructed beforehand digitally.
• said mapping of said wavelength l is constructed by a three-dimensional finite element approach.
• said specific thermal ratio y is determined by taking into account the composition of said enclosed mass, and by means of the thermal capacity of the components of said enclosed mass.
• said enclosed mass of gas is determined in real time.
• each specific thermal ratio y of each predefined enclosed mass of gas m 1 is determined; ..., m n by implementing the following steps:
• composition of said enclosed mass is determined;
• the frequency of pressure oscillations f is determined by means of an average over a time window of said determined oscillations.
• a wavelength l is determined for each mode of oscillation of said pressure of said gas.
• Figure 1 shows a cylinder of an internal combustion engine.
• FIG. 2 illustrates the steps of the method according to one embodiment of the invention.
• FIG. 3 illustrates the steps of calibrating the frequency of pressure oscillations according to one embodiment of the invention.
• Figure 4 illustrates a graph of the relative mass of gas estimated by the method according to the invention for an example.
• the present invention relates to a method for determining the mass of gas enclosed in a combustion chamber of an internal combustion engine.
• an internal combustion engine comprises at least one cylinder, a piston sliding in this cylinder in a reciprocating rectilinear movement, means for admitting an oxidizer (gas), means for exhausting burnt gases, a bedroom combustion, and injection means for injecting fuel into the combustion chamber.
• the combustion chamber is arranged in the upper part of the cylinder, and its volume varies by the movement of the piston in the cylinder.
• FIG. 1 illustrates, schematically and in a nonlimiting manner, a cylinder 1 of an internal combustion engine according to one embodiment of the invention. In this figure, the admission, exhaust and injection means, and any ignition means are not shown. Within the cylinder 1 moves a piston 6 in a reciprocating rectilinear movement.
• the combustion chamber 2 is the zone where combustion takes place, it is limited by the upper part of the piston 6, the side wall 4 of the cylinder, and the roof of the cylinder 5. This zone corresponds to the white zone in figure 1
• the cylinder comprises a pressure sensor 3, which measures the pressure of the gas in the combustion chamber 2.
• the internal combustion engine can be of any type, spark ignition or self-ignition, with or without exhaust gas recirculation, with or without supercharging.
• the method according to the invention is particularly suitable for spark ignition engines, and self-ignition engines equipped with exhaust gas recirculation (EGR) and / or variable timing.
• EGR exhaust gas recirculation
• gas or oxidizer it is understood air at ambient pressure or supercharged air or even a mixture of air (supercharged or not) with burnt gases.
• the method for determining the mass of enclosed gas uses a single sensor: a pressure sensor in the combustion chamber.
• a single sensor limits engine instrumentation.
• the measurement of the pressure in the combustion chamber makes it possible to have direct information relating to the behavior of the gas in the combustion chamber, unlike a sensor placed at the intake or the exhaust which would require rebuilding the gas. pressure in the combustion chamber.
• Such a sensor also has the advantage of conventionally equipping an engine test bench, and the internal combustion engines of recent vehicles, in particular for new self-ignition engines, which facilitates the implementation of the method, and which limit its cost.
• the method according to the invention comprises the following steps:
• these steps can be implemented in real time, in order to determine in real time the mass of gas enclosed, facilitating the exploitation of this parameter.
• these steps can be implemented online, on an internal combustion engine of a vehicle or on an engine test bench.
• the steps of determining the oscillations of the gas pressure and of determining the mass of enclosed gas can be implemented by computer means, in particular a computer fitted to the internal combustion engine.
• Figure 2 illustrates, schematically and in a non-limiting manner, the steps of the method according to the invention.
• the first step is to measure the pressure of the MES P gas in the combustion chamber, using a pressure sensor.
• the second step consists in determining the gas pressure oscillations OSC P from the gas pressure measurement carried out previously.
• the enclosed gas mass m is determined by determining DET f the frequency of pressure oscillations f with the pressure oscillations determined in the previous step.
• the gas pressure in the combustion chamber is measured by means of a gas sensor placed in the combustion chamber.
• this step can be implemented by means of a filter, preferably by means of a bandpass filter around the frequency of interest.
• a filter preferably by means of a bandpass filter around the frequency of interest.
• a Butterworth filter can be used.
• V is the volume of the combustion chamber (variable over time)
• l is the wavelength in the combustion chamber
• P is the measured pressure of the gas in the combustion chamber
• y is the thermal ratio specific.
• the formula is representative of the physical phenomena of the gas in the combustion chamber, which makes it possible to precisely obtain the mass of enclosed gas.
• the volume V of the combustion chamber can be obtained by means of a map or a table of the volume of the combustion chamber as a function of the crankshaft angle of the internal combustion engine.
• This mapping reflects the variations in volume linked to the movement of the piston. The use of such a mapping makes it possible to make the determination of the volume of the combustion chamber fast, and usable in real time.
• the wavelength l depends on the position of the piston (it is therefore variable over time) and on the shape of the combustion chamber. According to an implementation of the invention, the wavelength l can be obtained by means of a mapping of the wavelength l as a function of the crankshaft angle of the internal combustion engine. The use of such a mapping makes it possible to make the determination of the wavelength l fast, and usable in real time.
• the map of the wavelength l can be constructed beforehand and digitally.
• the digital determination of the wavelength l makes it possible to determine a wavelength l for any shape of the combustion chamber.
• the determination of the enclosed mass does not include an approximation linked to the shape of the combustion chamber.
• the mapping of the wavelength l can be constructed by a three-dimensional finite element approach (applied to the combustion chamber) to solve the three-dimensional wave equation. at each crankshaft angle, and thus determine the ratio between the frequency of pressure oscillations and the imposed speed of sound.
• the inputs to the finite element approach can be:
• the wavelength l can be determined by other methods, for example analytically.
• a wavelength l can be determined for each gas pressure oscillation mode, so as to obtain more precise information.
• the specific thermal ratio is time dependent and varies from one operating point to another of the internal combustion engine.
• the specific thermal ratio y can be determined by taking into account the composition of the mass enclosed in the combustion chamber, and by means of the thermal capacity of the components of the mass enclosed in the chamber. combustion.
• this embodiment it is possible to take into account the volume fraction of the components of the fuel injected into the combustion chamber (for example the fraction volume of ethanol in gasoline), the ratio of quantity of air per quantity of fuel in the combustion chamber compared to the stoichiometric ratio, and the proportion of unburnt gases in the combustion chamber.
• this embodiment can implement the following steps:
• the coefficients of the chemical formula of the fuel are determined, for example the coefficients x, y, z for a fuel of the form CxHyOz (when the fuel is not a mixture, and when the fuel is a mixture, the coefficients of the basic components of the fuel, depending on the volume fraction of the components of the fuel);
• the heat capacity of the unburned mixture in the combustion chamber is determined, taking into account the coefficients of the chemical formula of the fuel (for example x, y, z), and the ratio of the amount of air to the amount of fuel in the combustion chamber in relation to the stoichiometric ratio.
• the thermal capacity of the mixture burnt in the combustion chamber is determined, taking into account the coefficients of the chemical formula of the fuel (for example x, y, z), the methodology possibly being identical to that described for the thermal capacity of the fuel. unburned mixture.
• the combustion balance equation (to determine the concentration of components in the burnt mixture) and the thermal Cp capacity equations for each component can be used.
• the thermal capacity of the fuel mixture is determined by combining the thermal capacity of the burnt mixture and the thermal capacity of the unburned mixture, according to one embodiment of this step, it is possible, for example, to consider that the fuel mixture comprises 50 % of mixture burnt and 50% of unburnt mixture (or any other distribution),
• the frequency of pressure oscillations can be determined by carrying out a calibration by means of the following steps:
• At least two predefined enclosed gas masses m 1 are considered; m n , these are at least two possible enclosed gas masses, n is an integer greater than or equal to 2, according to one aspect of the invention, the predefined enclosed gas masses m 1; ..., m n are contained in a predefined list prior to the process being carried out,
• a specific thermal ratio y is determined for each predefined enclosed mass of gas m 1; ..., m n , for example one can deduce from each predefined enclosed mass of gas m 1; ..., m n a temperature T in the combustion chamber, and by applying the steps described above, we can deduce the heat capacity of the mixture c p , which is then used to obtain the specific heat ratio y as a function of the crankshaft angle,
• Each pressure oscillation frequency f obtained in the previous step is compared with the measured pressure oscillations (determined in step 2), and the enclosed gas mass is determined as one of the enclosed gas masses predefined m 1; ..., m n , for which the frequency of pressure oscillations f minimizes the comparison, in other words, the mass of gas enclosed determined by the method is one of the predefined enclosed gas masses m 1; ..., m n : that for which the difference between the pressure oscillation frequency f and the measured pressure oscillations is minimal.
• the comparison may consist of a comparison of the oscillations. Preferably, only the frequency of the measured pressure oscillations is used for the calibration, the amplitude of the latter is not useful for the comparison.
• this step can consist of a generation of the pressure oscillations with the different determined frequencies then the oscillations obtained are compared with those determined in step 2, and the signal for which the oscillation of the signal is comparable to the oscillations is chosen. of the measured pressure.
• FIG. 3 illustrates, schematically and in a nonlimiting manner, this implementation of this step of the invention.
• at least two enclosed gas masses m 1 are predefined; ..., m n .
• At least two thermal ratios g 1 are deduced therefrom; ..., g p which correspond to the predefined enclosed masses of gas m 1; ..., m n .
• the oscillation frequency f can be obtained by any other calibration method, for example by a method of minimizing an objective function.
• the oscillation frequency can be determined by means of an average over a time window of said oscillations determined in step 2).
• the example relates to the comparison of the mass of enclosed gas determined according to the method according to the invention, with the mass of enclosed gas determined by LES simulation.
• LES simulation For this example, consider a supercharged internal combustion engine with a rotational speed of 5500 rpm, and consider 23 critical cycles that have been identified as having varying pressure oscillation levels.
• the combustion chamber of the internal combustion engine is equipped with two pressure sensors at different positions within the combustion chamber.
• FIG. 4 is a graph illustrating the mass m of gas locked in the combustion chamber as a function of the number N of the cycle considered.
• the mass m used in this graph is a relative value which corresponds to the ratio of the mass of gas locked in the combustion chamber obtained by the method according to the invention compared to the mass of gas locked in the combustion chamber obtained by simulation .
• a value close to 1 indicates a good correlation between the simulated values and the values obtained by the method according to the invention.
• To each N corresponds two enclosed masses of gas, each obtained by one of the two pressure sensors used. Note that the values (represented by the points) and their average represented by the dotted segment are very close to the value one.
• the method according to the invention makes it possible to accurately determine the mass of gas trapped in the combustion chamber.
• the points and averages of the two pressure sensors are close. Therefore, the method according to the invention is quite independent of the position of the sensor in the combustion chamber.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Combined Controls Of Internal Combustion Engines (AREA)
• Portable Nailing Machines And Staplers (AREA)
• Measuring Fluid Pressure (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=68733379

Family Applications (1)

Country Status (3)

Family Cites Families (6)

• 2019
  • 2019-09-13 FR FR1910139A patent/FR3100844B1/fr active Active
• 2020
  • 2020-09-02 EP EP20764095.4A patent/EP4028658A1/de active Pending
  • 2020-09-02 WO PCT/EP2020/074396 patent/WO2021047966A1/fr unknown

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