Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M15/00—Testing of engines
  • G01M15/04—Testing internal-combustion engines
  • G01M15/11—Testing internal-combustion engines by detecting misfire
• • 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
• • 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
  • F02D41/14—Introducing closed-loop corrections
  • F02D41/1497—With detection of the mechanical response of the engine
  • F02D41/1498—With detection of the mechanical response of the engine measuring engine roughness
• • 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
  • F02D2200/10—Parameters related to the engine output, e.g. engine torque or engine speed
  • F02D2200/1015—Engines misfires
• • 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
  • F02D41/009—Electrical control of supply of combustible mixture or its constituents using means for generating position or synchronisation signals

Definitions

• the present invention relates to a control method of a vehicle engine, especially automobile.
• the invention relates to a method of controlling an engine comprising a step of determining whether a misfire occurs during a combustion cycle in a combustion chamber of the engine.
• a known technique consists in detecting them by analyzing a pressure in a manifold of the engine.
• this pressure is used in combination with a neuron network whose training is implemented at the time of calibration of the engine on a test bench.
• EGR Exhaust Gas Recirculation
• the object of the invention is a method in which the presence of a misfire or a loss of combustion is detected reliably and quickly.
• a method for controlling an engine characterized in that it comprises a step in which the eventual occurrence of a loss or misfire in a combustion chamber of the combustion chamber is determined.
• motor by comparing the value of a sliding average of a predetermined magnitude of the motor with a predetermined threshold value. The use of such a comparison offers the particular advantage of reducing the measurement noise of the size.
• the method further comprises a step in which at least one value of the quantity, which is taken into account in the sliding average, is modified when one of the misfires is detected;
• the modification of the value consists in replacing it by that of an average carried out on a number m of the values of the quantity smaller than a number n of values taken into account in the sliding average or by the last determined value of the sliding average ; the step of modifying the value of the quantity is carried out if the presence of a loss of combustion has been determined;
• the method further comprises a step where the values taken into account in the sliding average are initialized if the presence of a loss of combustion has been determined;
• the possible presence of each of the combustion misfires is determined by comparing the value of the quantity with a predetermined threshold value
• the quantity is selected from the following group: a pressure of a gas in a cylinder of the engine, a mean pressure indicated in the cylinder, a specified specific consumption of a fuel injected into the cylinder, a torque of the engine;
• the magnitude depends on an energy release of a gas present in the combustion chamber
• the magnitude is estimated iteratively according to a crankshaft angle and in that this iterative estimate is in the form of:
• FIG. 1 is a motor adapted to implement the method of the invention; 'invention, FIG. 2 is a general flowchart of one embodiment of the method of the invention; FIG. 3 corresponds to a flowchart showing steps implemented according to a particular aspect of this embodiment.
• the motor in the invention typically comprises an injector or spark plug 1, one end of which is in contact with an internal zone of a combustion chamber 4.
• a piston 6 can in known manner slide along an axis of the chamber to rotate a crankshaft 10 via a connecting rod 7.
• inlet ports 3 and gas outlet 2 in the chamber are also provided.
• the fitter further includes sensors for measuring engine magnitudes.
• At least one of these quantities will be used in the control method of the engine according to the invention.
• a pressure in the cylinder of the chamber an indicated average pressure (PMI), a specified specific consumption (CSI) or a motor torque can be used as a quantity.
• the method uses a crank angle in particular to know a state of a combustion cycle.
• the sensors concerned are represented by the reference 9 for the crankshaft angle, and 5 for the aforementioned quantities.
• the engine further comprises an electronic box 8 adapted to implement the method of the invention.
• this box has inputs 11, 12 to which are routed signals from the aforementioned sensors. It furthermore has at least one output 13 from which it is able to deliver a signal to an actuator of the engine which plays a role in the control method.
• the actuator corresponds to the above-mentioned spark plug or injector 1.
• the housing 8 we will now describe an embodiment of the method implemented in particular by the housing 8.
• FIG. 2 shows a flowchart of this embodiment.
• the value of a pressure measured at the current cycle k has been designated by the variable yc (k).
• n-1 values are contained in an interval [yc (k-n + 1), yc (kl)].
• a sliding average, denoted y based on the n-1 values of said interval and on the value yc (k) is determined in a step 101.
• this sliding average is determined at step k by a relation of the type:
• a step 102 the value of the sliding average thus obtained is compared with a predetermined threshold value Sl.
• step 103 the process proceeds to a step 103 where the step k is incremented for a next combustion cycle, then to a step 104 where the last values of the measured pressure are updated in the cylinder.
• this variable initially contains zeros indicating by default an absence of combustion loss.
• step k in question a value of 1 is assigned to this variable when step 105 is implemented so as to indicate that a loss of combustion has been detected.
• a test 106 is performed to determine whether a particular action is to be implemented.
• the method sets up these actions (step 107).
• step 100 If not, it waits for the next burn cycle and returns to step 100. Different tests may be used.
• a test 106 may consist of analyzing whether at the step k where the loss of combustion is detected, a misfire has also been detected.
• test 106 in FIG. 2 may comprise a step 200 shown in FIG. 3, where the value yc (k) is directly compared with a predetermined threshold value S2.
• this variable initially contains zeros indicating by default an absence of misfire.
• step k a value of 1 is assigned to this variable when step 201 is implemented so as to indicate that a misfire has been detected.
• step 202 the value 0 is assigned to the failed variable (k).
• this step 107 the value of the sliding average is modified.
• this value can be modified by modifying at least one value yc contained in said interval taken into account in the calculation.
• the sliding average is initialized so that it becomes equal to the current value yc (k).
• the moving average be determined on yc (k) alone. In other words, from the step k this average is no longer based on n values but only one, and more precisely the current value yc (k).
• the average will be based on two values. The one we just talked about and the new value yc (k) measured at this step k.
• the test 106 which is capable of initiating this reset of the sliding average does not include the above condition of absence of misfire.
• the reset takes place when the combustion loss has been detected (this amounts to saying that there is a direct link between step 105 and step 107 of reset).
• FIG. 3 shows step 200 of the test on a misfiring followed by step 102 in which the presence of a loss of combustion is tested.
• step 203 If in this last step, it is concluded that there is no loss of combustion, go to a step 203, where appropriate action may possibly be implemented.
• such an action may consist in further modifying the value of the moving average.
• the value of the sliding average is chosen so that it is equal to the value yc (kl) at the preceding step, so that it is equal to an average of m of n values.
• yc the last m measured values yc, current value y (k) being excluded, consider an interval [yc (k-m-l); yc (k-l)].
• the moving average is based solely on a single value, which corresponds to the value yc during the misfiring, or yc (k).
• the current value yc (k) is replaced either by the previous value yc (kl) or by the average on m of the n preceding values, in step 104.
• the second case makes it possible to better restore the processed signal.
• the sliding average is then more faithful to the signal it filters.
• V represents a volume in the combustion chamber
• Q an energy present in the gases of the combustion chamber and ⁇ the crankshaft angle.
• Multiplication by 1 / V has the particular advantage of reducing this noise.
• the noise is advantageously reduced just before and after the bottom dead center.
• the expression (1) makes it possible to obtain a signal whose amplitude is particularly high at the moment of the top dead center, which offers an advantage for SOC start-up detection (SOC for "Start of Combustion”). in the Anglo-Saxon language).
• SOC SOC start-up detection
• the expression (1) is transformed into a discretized expression of recursive-type which is in the form: c where ⁇ , p and T correspond to a ratio of the specific heats cp and cv, a pressure and a temperature in the cylinder.
• V, p, T, ⁇ and m are function variables of the angle ⁇ and the only variables measured are p and ⁇ .
• the mass m is constant. It is further assumed that the ratio ⁇ is constant, preferably equal to 1.4, before combustion and up to the first instants thereof. According to this preferred aspect, the estimation of the volume V and its derivative is obtained by reading in a table of the volume function of the angle ⁇ .
• T 0 T, ⁇ - ⁇
• the temperature is estimated at each angle ⁇ as a function of an initial temperature corresponding to the temperature in the cylinder at a time when an intake valve closes.
• the quantity C is therefore estimated during a cycle. If during this cycle it has remained above a predetermined threshold value S2, it is considered that there has been no misfire.
• the threshold values can be determined once and for all at the time of engine tuning, for example on a test bench.
• the threshold value S 2 to be compared with the quantity C the value 0.5 will preferably be used in the example mentioned above.
• the threshold values can also be variable in time.
• certain threshold values preferably an amount of fuel injected per cycle in the combustion chamber or a motor speed.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Combined Controls Of Internal Combustion Engines (AREA)

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• 2005
  • 2005-12-20 FR FR0512940A patent/FR2895024B1/fr not_active Expired - Fee Related
• 2006
  • 2006-12-14 WO PCT/FR2006/051353 patent/WO2007074271A1/fr active Application Filing
  • 2006-12-14 EP EP06842163A patent/EP1963648A1/de not_active Withdrawn

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