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
  • F02D41/14—Introducing closed-loop corrections
  • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
  • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
  • F02D41/1454—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an oxygen content or concentration or the air-fuel ratio
  • F02D41/1458—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an oxygen content or concentration or the air-fuel ratio with determination means using an estimation
• • 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
• • 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
  • F02D41/30—Controlling fuel injection
  • F02D41/3011—Controlling fuel injection according to or using specific or several modes of combustion
  • F02D41/3017—Controlling fuel injection according to or using specific or several modes of combustion characterised by the mode(s) being used
  • F02D41/3035—Controlling fuel injection according to or using specific or several modes of combustion characterised by the mode(s) being used a mode being the premixed charge compression-ignition mode
• • 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
  • F02D2200/1002—Output torque
• • 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
  • F02D2250/18—Control of the engine output torque
• • 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
  • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
  • F02D41/1454—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an oxygen content or concentration or the air-fuel ratio

Definitions

• the present invention relates to internal combustion engines of the Diesel type equipped with a closed-loop control device of the indicated average torque or of the average pressure indicated in the cylinders with regulation of the quantity of fuel injected with respect to a value of setpoint.
• the subject of the invention is also a process for producing a reference value of the quantity of fuel injected into the combustion chamber of a cylinder of such a diesel type internal combustion engine.
• the invention applies to internal combustion engines of the Diesel type with direct or indirect fuel injection and comprising at least one cylinder and generally several cylinders.
• the invention applies regardless of the type of diesel combustion, whether homogeneous or conventional and in particular the HCCI type engine. .
• the driver's request can be translated into torque and can be used directly as a reference value for the control system.
• the quantity to be injected is predefined in advance and the motor does not have information to check whether the quantity actually injected is correct.
• the proportion of air admitted into the cylinder always corresponds to the proportion of fuel required to achieve a desired richness, even in the event of significant variations in torque demand from the driver of the vehicle.
• the regulation can be improved and the differences can be avoided from one engine to another in order to better control the combustion by using a regulation of the quantity of fuel to be injected in a closed loop.
• JP 2,337,194 (Sanshin)
• US 6,095,127 (Ford Global)
• JP 05
• Spark ignition engines are also known comprising a regulation of the air / fuel ratio as a function of the pressure measured in the cylinder (see in particular WO 2006/054 794 (Toyota) Japanese Patent Application JP 2002 354 450 (NGK) is also relates to a spark ignition engine and describes a device for controlling and regulating combustion from a measurement of the pressure in the cylinder.
• German Patent Application DE 4 126 182 (Mitsubishi Denki) describes a diesel-type combustion engine comprising a crankshaft angle sensor and a cylinder pressure sensor whose signals are fed to a control device. fuel injection and wealth. Regulation is however in open loop. Finally, it is still known by the US patent application 2005
• 0229 903 (Toyota), a closed - loop regulation of the quantity of fuel to be injected into a diesel engine using as input signals the pressure measured in the cylinder and the angle of the crankshaft.
• the injection control is however carried out here by means of a specific and precise phasing of the injection of fuel into the cylinder.
• the present invention proposes to improve the control devices used in internal combustion engines of diesel type, in particular in the case where it is desired to make the combustion as homogeneous as possible, without risk of damaging the engine. because of a too high richness, especially during transient phases, for example in case of sudden acceleration requested by the driver of the vehicle. It concerns direct injection diesel engines.
• the present invention aims to enable a real-time control of the engine operation by constantly acting on the operating parameters of the engine, so that it provides at all times optimal performance and remains in a controlled operating range.
• the object of the invention is also to improve a closed-loop control device of the quantity of fuel injected into the combustion chamber of a diesel-type internal combustion engine cylinder.
• a diesel type internal combustion engine comprising at least one cylinder with a combustion chamber and a fuel injector, is equipped with a closed-loop control device of the indicated average torque (CMI) or the indicated average pressure (PMI), capable of developing a set value of the quantity of fuel injected.
• CMI indicated average torque
• PMI indicated average pressure
• the regulating device comprises a limiting means capable of comparing the fuel / air ratio in the combustion chamber with a threshold value and of limiting, when said threshold is exceeded, the value of a variable chosen from the set quantity reference.
• injected fuel the indicated average pressure setpoint (PMI) and the indicated average torque setpoint (MIC).
• PMI indicated average pressure setpoint
• MIC indicated average torque setpoint
• the limiting means is capable of maintaining said variable equal to the value it had a moment ago.
• the limiting means may also be capable of giving said variable a default value.
• the internal combustion engine comprises means for determining the fuel / air ratio in the combustion chamber, for example a richness probe, a wealth evaluation device, or a ratio estimation device. fuel / air.
• the internal combustion engine may further include a cylinder pressure sensor and a crank angle sensor of the engine crankshaft.
• a method for preparing a set value of the quantity of fuel injected into the combustion chamber of a cylinder of internal combustion engine of the Diesel type in which one compares the fuel / air ratio in the combustion chamber with a threshold value and, depending on the result of the comparison, limits the value of a variable selected from the set fuel quantity injected, the indicated average pressure setpoint (PMI) and the indicated average torque setpoint (MIC).
• FIG 1 schematically illustrates one of the cylinders of a diesel type internal combustion engine according to the invention
• FIG. 2 diagrammatically illustrates the main elements of the control device used in an engine according to the invention with limitation of the quantity of fuel injected;
• FIG. 3 is a diagram showing the various steps of a procedure for limiting the quantity of fuel injected
• FIG. 4 shows various curves illustrating the influence of a transient variation of the fuel / air ratio with and without the process of limiting the quantity of fuel injected according to the invention
• FIG. 5 shows another embodiment of a regulating device that can be used in an engine according to the invention
• FIG. 6 is a diagram showing the limiting strategy applied to the average pressure indicated in the embodiment of FIG. 5;
• FIG. 7 shows, by different curves, the effect of the limitation on the reference value of the indicated average pressure;
• FIG. 9 illustrates, by different curves, the effect of the limitation on the reference value of the average pressure indicated in the case of the variant of FIG. 8.
• FIG. 1 diagrammatically shows in section a cylinder 1 of an internal combustion engine of the Diesel type with a piston 2 defining, with the upper part of the cylinder 1, a combustion chamber 3.
• the piston 2 is connected to a connecting rod 4, itself driven by a crankshaft 5.
• the combustion chamber 3 communicates with an intake zone 6 equipped with an intake valve 7 and a zone of combustion.
• Exhaust 8 equipped with an exhaust valve 9.
• An injector 10 opens into the upper part of the combustion chamber 3.
• a sensor 1 1 of the crankshaft angle is capable of delivering information on the rotation of the crankshaft 5 to an electronic control unit 12 for controlling the operation of the engine.
• a pressure sensor 13 is capable of measuring the pressure in the combustion chamber 3 and delivers a signal to the control unit 12. The latter is capable of transmitting a control signal via a connection 14 to the injector 10.
• the control of the quantity and the moment of the injection of fuel by the injector 10 is by a regulating device illustrated schematically in FIG. 2.
• the input quantity of the regulation can be the pressure measured in the combustion chamber by the sensor 13.
• the control device for example, the indicated average torque (CMI) or the indicated average pressure (PMI) as a set value. These are theoretical nominal values provided by the manufacturer for several engines of different displacements.
• CMI average torque indicated
• ⁇ is the angle of the crankshaft measured by the sensor 1 1
• V 1 is the volume of the combustion chamber of the cylinder i throughout the operating cycle
• P 1 is the pressure in the combustion chamber of the cylinder i
• N cy i is the number of cylinders of the engine considered.
• the indicated average pressure (PMI) is related to the average torque indicated by the formula:
• V cy i is the unit cubic capacity
• variable to be regulated is thus a reference quantity of the indicated average pressure (PMI) or the indicated average torque (CMI). which is fed to one of the inputs of the subtractor 15 which also receives on its second input, by the feedback branch 16, the measured value of the same quantity, either the indicated average pressure (PMI) or the indicated average torque ( MIC) determined according to formulas (I) or (II) by the control unit 12.
• the error signal from the subtractor 15 is fed to a correction device 17 whose output signal is connected to a adder 18 which receives on another input 19 a prepositioning signal which makes it possible to accelerate the dynamics of the control.
• the signal coming from the adder 18 corresponds to the quantity of fuel that must be injected by the injector 10. This signal is fed to the various injectors 10 of the diesel engine shown schematically by the block 20 in FIG.
• This control device is completed by a limitation means referenced 21 as a whole in FIG. 2.
• This limitation means requires knowledge of the fuel / air ratio (or air / fuel ratio). This information can be obtained by means of a richness probe, by an assessment of the richness by means of an exhaust gas analysis device or by an estimate or calculation of the fuel / air ratio. Figure 2 illustrates this latter possibility.
• the quantity of air admitted into the air cylinder and the quantity of injected fuel q inj are fed to the two inputs of a calculation block 22 which calculates the fuel / air ratio, the value of which is brought to the
• the block 23 receives on three other inputs: the value q inj of the quantity of fuel injected by the connection 24 at the previous time step in the sampling of the regulating device; a default fuel limitation value which is stored in the memory zone 25 and which is denoted q -lim- limit-fault and a threshold value for the fuel / air ratio stored in the memory zone 26 which is noted threshold-report on This threshold ratio can be easily determined by simple routine tests. It is generally between 1, 5 and 2.
• the block 23 outputs a set value of the amount of fuel injected which is fed to the input of an activator block 27 which plays a saturation role and which receives on another input the output of the first adder 18. From In this way, the set value of the quantity of fuel injected which is supplied to the injectors of the engine 20 can be either the reference value coming from the calculation block 23 belonging to the limiting means 21, or the reference value coming from the adder 18. In the example illustrated in FIG. 2, the corrector device
• the saturation means can then use the limitation of the quantity of fuel injected which is brought to it at the output of the limiting means 21 via the connection 28.
• the set value of the quantity of fuel injected, determined by the Limiting means 21 may be used both at the input of the motor 20 and in the correction device 17 to improve the saturation strategy of the integral part of the control.
• the quantity of fuel injected is directly limited by opening the control loop in some way by means of the activator block 27, in order to act directly on the
• the limitation thus made consists in limiting the quantity of fuel injected to the last quantity actually injected before the air / fuel ratio exceeds the stored threshold value.
• the device operates in a manner that is illustrated in Figure 3, which describes the operation temporally, each time step being noted k.
• k -1 denotes information given in the previous time.
• the entire operation can be implemented by hardware means or software.
• Step 29, visible in FIG. 3 defines the fuel / air ratio at step k.
• This value was compared in step 30 this value to the value indicated threshold threshold ratio. If the value of the fuel / air ratio is greater than the threshold, the value of an index variable, noted as Index (k), is analyzed.
• variable Index (k) If the variable Index (k) is equal to 0, it is the first time that the threshold of the fuel / air ratio is exceeded. This information is recorded by assigning the value 1 to the variable Index (k) in step 32. At the same time, the quantity of injected fuel q inj - limit (k) takes the value of the step fuel quantity instruction. previous time, namely q inj- set (k-1), that is to say the value that was before the threshold was exceeded.
• variable Index (k) 1
• q inj - limit (k) q inj - limit (k - 1) .
• step 34 If the fuel / air ratio is below the threshold, proceed to step 34.
• step 39 is carried out which forces the reference value of the quantity of fuel to the setpoint value before the limiting means, ie the value which appears in FIG. the output of the adder 18.
• FIG. 4 shows the results that can be obtained thanks to the limitation means associated with the control device as illustrated in FIG. 2 and operating as indicated in FIG.
• Figure 4 illustrates the curves as a function of time of three quantities which are, for the top graph, the ratio fuel / air, for the graph of the medium, the duration of injection in milliseconds, and for the graph of the bottom , the indicated average pressure (PMI) in bars.
• dashed the operation of a conventional control device does not include the limitation means 21 shown in Figure 2, and solid lines the operation with the limiting means 21 shown in Figure 2
• the value of the fuel / air threshold ratio is also shown in phantom.
• FIG. 5 illustrates another embodiment, in which this time is no longer a direct limitation of the quantity of fuel injected, but on the contrary a limitation of the set value of one of the setpoint variables that constitute the indicated average pressure (MIP) or the indicated average torque (MIC).
• FIG. 5 does not show, for the sake of simplification, the limitation means 21 which is, however, similar to that illustrated in FIG. 2.
• the output signal of the limiting means is brought directly to a activation block 40 placed at the input of the regulating device, that is to say at the input of the subtractor 15.
• the limiting means 21 acts only on the block 40 without modifying the operation of the whole of the regulating device.
• the structure and operation of the limiting means are substantially similar to those of the previous embodiment.
• MIP indicated average pressure
• MIC indicated average torque
• Figure 7 shows three graphs similar to those of Figure 4 the result obtained on the three variables that are the fuel / air ratio, the injection time and the average pressure indicated.
• the upper curve shows that at a time corresponding to approximately 5 seconds, a limitation is made on the set value of the indicated average pressure PMI from a threshold value of the fuel / air ratio always set at 1.5. .
• a retained decrease in the indicated average pressure which tends rapidly to stabilize at a value close to 10 bars.
• the threshold value exceeds the fuel / air ratio
• the set value of the indicated average pressure is acted on, thus limiting the increase in the ratio.
• fuel / air as shown by the solid line curve of the upper graph.
• the injection time shown in solid lines on the median graph is not kept constant as it was the case in the previous embodiment (median graph of Figure 4), but its increase is however limited.
• FIG. 8 An alternative embodiment has been illustrated in FIG. 8, where there are similar steps bearing the same references as in FIGS. 3 and 6.
• the limitation process is done more quickly and without going through the index variable used in the operation illustrated in FIGS. 3 and 6.
• the set value of the indicated average pressure is directly constrained. saturating it with the limiting value defined previously. In other words, if the indicated average pressure (PMI) is greater than the PMI limit value (k), the indicated average pressure PMI is set to the limit value in step 38. the set value of the indicated average pressure PMI takes the value of the setpoint before the limiting means.
• the stabilization of the set value of the indicated average pressure is therefore less good than in the operation illustrated in FIGS. 6 and 7.
• the quantity of fuel injected is smaller, so that the fuel / air ratio is thus more effectively limited.

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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)

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• 2007
  • 2007-04-19 FR FR0754583A patent/FR2915241B1/fr not_active Expired - Fee Related
• 2008
  • 2008-04-02 WO PCT/FR2008/050584 patent/WO2008139091A2/fr active Application Filing
  • 2008-04-02 EP EP08788109A patent/EP2134947A2/de not_active Withdrawn

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