Classifications

• • 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
  • F02D41/008—Controlling each cylinder individually
• • 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
  • F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
• • 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
  • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
  • F02D41/1439—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the position of the sensor
• • 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
  • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
  • F02D41/1477—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the regulation circuit or part of it,(e.g. comparator, PI regulator, output)
  • F02D41/1481—Using a delaying circuit
• • 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
  • F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
  • F02D2041/1409—Introducing closed-loop corrections characterised by the control or regulation method using at least a proportional, integral or derivative controller
• • 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
  • F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
  • F02D2041/1413—Controller structures or design
  • F02D2041/1415—Controller structures or design using a state feedback or a state space representation
  • F02D2041/1416—Observer
• • 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
  • F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
  • F02D2041/1413—Controller structures or design
  • F02D2041/1415—Controller structures or design using a state feedback or a state space representation
  • F02D2041/1417—Kalman filter
• • 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
  • F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
  • F02D2041/1413—Controller structures or design
  • F02D2041/1418—Several control loops, either as alternatives or simultaneous
• • 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
  • F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
  • F02D2041/1433—Introducing closed-loop corrections characterised by the control or regulation method using a model or simulation of the system

Definitions

• the invention relates to systems for injecting fuel into the combustion chambers of an internal combustion engine, and in particular of a spark ignition engine; it particularly relates to devices making it possible to estimate the air / fuel ratio admitted into the combustion chambers usable in such systems.
• a device for estimating the richness of the mixture admitted into each of the n combustion chambers (n being an integer greater than 1 and generally equal to 4, 6 or 8) of an engine having injectors d injection into the cylinders, comprising:
• Such a device can be used in particular in an injection system of the kind shown schematically in figure 1.
• the air admitted through a filter 14 passes through a throttle body 16 before arriving at a manifold intake 18.
• the exhaust gases leave the chambers through individual pipes which connect at a point of confluence to an exhaust manifold 20.
• the quantities of fuel supplied to each cylinder at injection times are set by a computer 21 on the basis of operating parameters which may in particular include:
• a simple model for representing the wealth measured at the confluence point consists in associating, with the measurement made by the sensor 26 with several successive passages of the combustion chambers at top dead center, a weighting coefficient which is solely a function of the age of the passage in the engine operating cycle.
• the entry of the model is the wealth admitted to the combustion chamber which has just shifted to top dead center
• the present invention aims in particular to provide an estimation device which responds better than those previously known to the requirements of practice, because it very significantly reduces the incidence of asymmetries and, in the case of asymmetry specifically, the invention improves the correction of dispersions of characteristics of the mjectors.
• the invention notably proposes a device in which the behavior model comprises a particular sub-model per combustion chamber having, for the order chamber i, a Kalman filter having an mxn matrix of coefficients ⁇ ⁇ and a own K earnings matrix, i being equal to ⁇ 1, n ⁇ corresponding to the room number and corresponding to the weighting coefficient number, here from 1 to m.
• the invention proposes a different model for each room i, defined by a set ⁇ of m coefficients, m being able moreover to be equal to n.
• the model can be represented by one or more matrices (C) each corresponding to an operating zone. of the engine determined by one or more parameters from the load range, the exhaust gas temperature, the temperature of the cooling water, the engine speed and the pressure in the intake manifold.
• the matrix chosen can also depend on the setpoint richness given by the computer and which can depend on the engine operating conditions according to the constraints on pollution or driving pleasure.
• FIG. 1 schematically shows the elements of an engine concerned by the invention
• FIG. 2 is a block diagram showing the main sub-assemblies of a device according to the invention, and function of these sub-assemblies which can be produced by hardware or by software
• FIG. 3 is a functional diagram of means for compensating for the measurement delay introduced by the richness sensor
• FIG. 3A indicates typical response curves of the means of FIG. 3
• FIG. 3B shows a phase response curve as a function of the frequency
• Figure 4 is a block diagram of synchronous wealth acquisition means, combustion chamber by combustion chamber
• FIG. 5 is a diagram of means for correcting wealth.
• Figure 6 shows an error handling block of richness incorporating the means of fig. 5.
• the device according to the invention has the basic principle shown in FIG. 2. Most of the functions are fulfilled by the computer 21. However, some of them, and in particular functions for filtering fixed characteristics, can be performed in analog form. by wired circuits.
• the device comprises a compensator 32 intended to compensate for the delay introduced by the sensor 26.
• Means 34 for synchronous wealth acquisition can be regarded as having an observer 36 with Kalman filtering and correction means 38 supplying the air reports as output / fuel admitted to the chambers during the cycle which has just elapsed.
• the correction means receive a synchronization signal constituted by the output of the sensor 28 followed by a circuit 40 of modulo n division, here equal to 4.
• Synchronization must be initialized, the sensor 28 not making it possible to know which combustion chamber has just shifted to top dead center. This initialization can be carried out by various known methods.
• management means 42 determine the opening times of the injectors 12 on the basis of information produced by the computer 21, constituted for example by the admitted air flow and by the required richness, and from the corrections provided by the means 38.
• the model allowing the synchronous acquisition means 34 to determine the richness of the mixture admitted to each chamber is based on the measurements provided by the single sensor 26 located at the point of confluence. It is important to have, after each change to top dead center, a measurement representative of the richness while a combustion chamber has just shifted to neutral.
• the usual sensors in particular because they include a pierced protective cover of the probe, introduce a measurement delay.
• FIG. 3 The strategy adopted is represented functionally in FIG. 3.
• the signal coming from the probe is subjected to a high pass filtering 43 whose characteristics take into account the time constant ⁇ of the cover of the sensor of several tens of ms.
• the value taken into account in the high pass filter will be linked to the lowest time constant among all those that can be encountered under the various operating conditions of the engine.
• the high pass filter 43 amplifies the noise which is attenuated or eliminated by a feedback loop comprising a low pass filter 44, an adder 46 receiving the output of the low pass filter and an input signal and a subtraction 48.
• the high pass and low pass filters introduce gains and are provided so that these gains vary as a function of the frequency according to laws which may be those indicated respectively by the solid and mixed lines curves of FIG. 3A.
• the low pass filtering may be simply first order. The compensation being ensured in digital form, on discrete values, one can confine oneself to carrying out a transformation of Euler.
• ⁇ denotes the low pass filtering gain, intended to eliminate the high-frequency noise generated or amplified by the high-pass inversion filtering.
• the richnesses thus measured and compensated are used as inputs for the Kalman filtering observer 36.
• this Kalman filtering is generally carried out by adopting the same Kalman gain and the same weighting coefficients whatever the combustion chamber for which the wealth is to be determined.
• an optimal anticipation Kalman gain K is determined and a weighting coefficients C have been obtained for each of the combustion chambers.
• Each of these elementary observers can have a relatively classic constitution.
• the calculation making it possible for example to determine the richness of the cylinder 1 corresponds to the orientation of switches 52 given in FIG. 4, the switches being in fact constituted by a program making it possible to carry out the permutation of the gains and coefficients for the calculation .
• the successive measurements y mes (k) at the confluence point are accumulated at 54 and processed by an operator z at 56, the output of which is reduced, by a gain loop 58, to accumulation 54.
• the value y is (k) obtained at exit 60 is representative of the richness estimated at the point of confluence. It is re-introduced into an input subtractor 62, so as to generate an error signal e (k) which is applied to the input of the Kalman filtering.
• the weighting coefficients C i • can be obtained experimentally by identification by means of a measurement bench using a set of probes capable of measuring the richness on each tubing and the richness at the point of confluence. The richness of the current cylinder is then available at the output 64 of the accumulator 54.
• the correction means receive, as inputs: the signal of richness measured and compensated, at the point of confluence, coming from the memory 50, signals indicating the estimated richness of the current cylinder, coming from the output 64 of the observer, and the synchronization signal coming from the divider 40 modulo 4.
• the richness correction to be made to a cylinder to be determined is calculated in the form of a product of two terms, a term 1 + ⁇ _, ⁇ being a percentage of general correction relating to the richness measured at the point of confluence, a term 1 + ⁇ i, particular to the cylinder of order i in which the injection will be ordered.
• the first term is developed from an error signal supplied by a subtractor 66 which receives on the one hand a signal representative of the richness setpoint (which depends on the operating conditions of the engine) and on the other hand the signal output from memory 50.
• An error management module 68 develops a corrective term, which is processed by a proportional-integral filter 70 intended to stabilize the system. We thus obtain ⁇ g.
• ⁇ i are each developed using a subtractor 72 which receives on the one hand the output signal 64 modulo 4, developed by a switch 5, and on the other hand a richness set signal specific to the cylinder.
• This richness setpoint signal can be the same for all the cylinders. The wealth setting could also be different depending on the cylinder.
• the error signal obtained is still subjected to proportional-integral filtering 74, called PI, to obtain a correcting term ⁇ i.
• a circuit 76 will make it possible to develop the product (1 + ⁇ i) (1 + ⁇ g) which constitutes a correction factor over the injection time of the cylinder i.
• the PI filtering has a role in compensating for the gas travel time between the injection points and the confluence point.
• the richness error management module 68 has the role in particular of making the switchings of the sensor faster by acting on the error injected into the PI filter 70. It introduces, in addition to an amplification of the richness error , a hysteresis causing a tilting of the sensor only beyond the stoichiometry when one goes towards a rich mixture, below the stoichiometry when one returns to a lean mixture. Beyond the failovers, the management module has a substantially proportional response.
• the proportional gain factors ⁇ _ and integral K ⁇ of the correction filters 74 are chosen as a function of the travel delay between the injectors and the richness sensor, counted in number of TDCs. K_ will generally be less than 1 to attenuate the high frequencies. K j _ can be of the form:
• K j _ K_ x P x (2 / delay time) for a 4-cylinder engine.
• P is an adjustable constant to adjust the dynamics.
• the management circuit 42 (FIG. 2) allows, from an input signal 78 indicating the quantity of air admitted to the cylinder and from the corrector term received from the means 36, to modify a basic injection time corresponding to the richness setpoint for fixing the opening time of each of the injectors 12 and controlling the injector.
• This circuit can in fact comprise a digital calculation part incorporated into the computer 21 and an analog and power part developing the pulsed current supplying the injectors.
• the wealth management circuit can correspond to the block diagram of FIG. 6.
• the wealth instruction for the injector i is applied to the input 80 and multiplied by a signal 82 representative of the quantity of air admitted.
• the product is multiplied by the gain of the injector in 84 for obtain a base injection time Ti.
• the correction signal supplied by the means in FIG. 5 is used to supply Ti (1 + ⁇ .) (1 + ⁇ )
• Establishing the model requires determining the weights for a given engine. This determination can be made on a test bench by temporarily equipping the engine with richness probes at the outlet of each cylinder, in addition to the final sensor.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
• Combined Controls Of Internal Combustion Engines (AREA)

Applications Claiming Priority (3)

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• 1998
  • 1998-01-19 FR FR9800502A patent/FR2773847B1/fr not_active Expired - Fee Related
• 1999
  • 1999-01-15 BR BRPI9907102-9A patent/BR9907102B1/pt not_active IP Right Cessation
  • 1999-01-15 US US09/600,264 patent/US6357429B1/en not_active Expired - Lifetime
  • 1999-01-15 JP JP2000540368A patent/JP2002527657A/ja active Pending
  • 1999-01-15 EP EP99900932A patent/EP1049862B1/de not_active Expired - Lifetime
  • 1999-01-15 DE DE69902992T patent/DE69902992T2/de not_active Expired - Lifetime
  • 1999-01-15 WO PCT/FR1999/000072 patent/WO1999036690A1/fr active IP Right Grant

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