Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L3/00—Measuring torque, work, mechanical power, or mechanical efficiency, in general
• • 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
  • G01M15/042—Testing internal-combustion engines by monitoring a single specific parameter not covered by groups G01M15/06 - G01M15/12
  • G01M15/046—Testing internal-combustion engines by monitoring a single specific parameter not covered by groups G01M15/06 - G01M15/12 by monitoring revolutions
• • 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
  • F02D2200/1004—Estimation of the output torque
• • 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

Definitions

• the invention relates to a method for calculating the torque of a four-stroke internal combustion engine with electronically controlled injection, in particular mounted in a motor vehicle.
• the torque measured is the average gas torque produced by the combustion of the air-petrol mixture in the different cylinders. It is interesting to measure the torque with precision over a large number of combustions to optimize certain engine settings, in particular thanks to the electronic injection computer and to diagnose certain malfunctions, including misfire or "misfire".
• a misfire in a cylinder of a controlled injection engine can be due to a lack of spark, a bad dosage of fuel, or a bad compression for example.
• This recognition of bad combustion is required by European EOBD (European On Board Diagnostic) or international OBD II (On Board Diagnostic) regulations concerning on-board diagnostic systems in vehicles, for the control of exhaust system emissions with a view to compliance with anti-pollution standards.
• the method of measuring such a torque uses a device comprising a target in the form of a crown, integral with the flywheel of the engine or the crankshaft and provided with markers on its circumference, teeth for example, running past a fixed sensor.
• the instantaneous value of the period of movement of the teeth in front of the sensor corresponds to the measurement of the instantaneous power produced in each of the cylinders of the engine successively.
• Electronic calculation means use the signal delivered by the sensor to calculate the average gas torque C produced by each combustion of the gas mixture in each of the engine cylinders.
• each of the four cycle times - intake, compression, combustion-expansion, exhaust - occurs during a particular U-turn of the flywheel integral with the engine crankshaft.
• the kinetic energy acquired by the system concerned, namely the crankshaft and the flywheel with alternative masses, is the result of the different instantaneous negative and positive torques exerted on it during each of the different times of the engine operating cycle.
• the gas torque Cg is calculated at each half-turn. This torque is generated during these compression and combustion-expansion phases of the gas mixtures respectively trapped in two contiguous combustion cylinders (1 and 4, 2 and 3). The other two cylinders are then in the intake and exhaust phases.
• the target has, on its periphery, 57 identical teeth regularly spaced and each formed by a niche and a hollow, and a reference tooth, of greater width equivalent to three other teeth, serving as the origin of 'indexing to allow numbering of said teeth.
• the angular period T of the combustions concerns 30 teeth and is equal to half the period of rotation of the crankshaft.
• the angular period of combustion T only concerns 20 teeth, etc.
• the fixed sensor can be of variable reluctance, adapted to deliver an alternating signal of frequency proportional to the speed of movement of the teeth of the crown, that is to say proportional to the instantaneous speed of the flywheel.
• a current method for calculating the average gas torque is described in the French patent application filed under the number 95 06780, in the name of the applicant, consisting of: - producing a primary numerical value d ⁇ representative of the instantaneous duration of scrolling before the sensor of each of the target teeth,
• ⁇ is a constant term proportional to the rotary inertia of the motor and ⁇ is a term which is a function of the moment of inertia of the alternating masses.
• the invention aims to learn and correct the defects of the target, as well as adapting to dispersions and wear of the motors.
• the object of the invention is a method of calculating the torque of an internal combustion engine, with injection controlled by an electronic computer, the engine being such as a target, for example in the form of a toothed ring.
• the engine being such as a target, for example in the form of a toothed ring.
• a tooth deflection sensor fixedly mounted in the vicinity of the target delivering a signal to electronic means for calculating the torque, consisting, from digital values d ⁇ representative of the instantaneous running time in front of the sensor of each of the teeth, to develop a numerical value ⁇ representative of the projection, on the phase reference line of the teeth corresponding to the origin of the angular periods of the combustions, from l amplitude of the alternating component of instantaneous durations d; at the frequency of combustion in the engine, characterized in that it consists in correcting the defects of the target by the following steps:
• FIG. 1 a front view of a toothed target, mounted on the flywheel of an internal combustion engine
• FIG. 3 a flow diagram of the different steps of the method of calculating the engine torque according to the invention.
• the invention applied to a four-stroke four-cylinder internal combustion engine, consists in learning the faults of each half-turn of the toothed target mounted at the end of the crankshaft, with the aim of correcting the calculation of the torque medium gas produced with each combustion. Indeed, there are significant differences in measured torques according to the U-turn target on which the calculation is made. These deviations can have several causes, such as for example the machining of the target, a front view of which constitutes FIG. 1. An imperfect machining of the target 1 causes defects in the measurements of durations of passage of each tooth 2 in front of the sensor 3, as well as a bad centering of the axis 4 of the target which no longer turns in a circle.
• Improper machining of the locating tooth 5 causes the electronic input stage of the torque measurement device to reflect an error in the calculation which leads to distortions of the signal.
• mounting the target at the end of the crankshaft can cause torsion and bending problems of the crankshaft. In all cases, the defect results in errors in the measurement of the time elapsed for a given angular displacement of the target.
• T a numerical value representative of the total running time before the sensor of each series of n teeth defining the angular interval of combustion in the engine
• ⁇ a representative value of the projection, on the phase reference line of the teeth corresponding to the origin angular periods of the combustions, the amplitude of the alternating component of the instantaneous durations d ⁇ of movement of the teeth in front of the sensor at the frequency of the combustions in the engine.
• the correction of the mean gas torque therefore implies a correction of the previous equation at the level of the term in N 2 , that is to say the learning of a term ⁇ relating to the angular segment to be learned.
• N 2 the level of the term in N 2
• ⁇ the degree of the term in N 2
• T ⁇ i being an integer equal to 1 or 2
• the calculation of the couple C Q ⁇ is carried out from the term ⁇ according to equation (E) which becomes:
• C gi ⁇ ( ⁇ N + ⁇ ⁇ ) ⁇ 2 .
• the learning of the term ⁇ ⁇ takes place under torque conditions corresponding to an absence of combustion, otherwise called non-combustion, in all the cylinders, such as for example during a cut-off. fuel injection by the electronic computer.
• This state of zero gas torque must be recognized, ensuring that none of the cylinders generate engine torque.
• the learning of the values of ⁇ ⁇ consists of a first step called rapid learning, taking place over a determined number P of successive top dead centers in non-combustion, for example at the end of production line of the vehicle on which the engine is mounted, controlled by an electronic ignition-injection computer, and of a second stage known as slow learning, during engine operation.
• the first quick learning step consists in calculating the average j. of the first values of the term? j _ (pmh), calculated from equation (E-,), on a determined number P of top dead centers, in non-combustion, a hundred for example, (pmh) being an integer between 1 and P corresponding to the serial number of top dead center initialized at the start of operation of the computer:
• This step enables good learning to be carried out at the end of the production line, under stable, controlled and known operating conditions, on a roller bench for example, thanks to rapid adaptation to manufacturing dispersions.
• This average value ⁇ im 'stored in the electronic computer is then used to calculate the torque C, from the output of the vehicle chain.
• the slow learning step consists, at each non-combustion phase, whatever its duration counted in top dead center, to strongly filter each value of the term ⁇ (pmh) corresponding to the half -turn of order i, calculated at each top dead center of order pmh, so as not to take into account values learned under conditions not representative of the operation of the engine.
• the value 3 jf (mh), obtained by this first order filtering is equal to the filtered value ⁇ ⁇ (pmh-1) at previous top dead center of order pmh-1, to which is added a fraction of the difference between the value / î '(pmh) measured and the filtered value (pmh-1):
• q being the filtering coefficient determined according to the desired response time for taking learning into account and pmh being an integer greater than P and less than or equal to D, corresponding to the end of the deceleration phase.
• slow learning takes place between two engine speed thresholds, which are calibration variables.
• two engine speed thresholds which are calibration variables.
• FIG. 3 groups together, in the form of a flowchart, the different steps of the method for calculating the torque of an engine according to the invention.
• this process calculates the average gas torque at each top dead center, referenced by the pmh index, so that at each of them, step a, consisting in recognizing whether the engine is in phase combustion or non-combustion, by cutting fuel injection into the cylinders for example, must be performed.
• step b the learning conditions concerning for example the engine speed N or the throttle leakage flow rate must be fulfilled (step b) for the calculation of the terms ⁇ ⁇ and? 2 , for each of the two half-turns, is carried out (step c) from the value of the pressure in the intake manifold P co ⁇ •
• the terms ⁇ -, and? 2 thus calculated are then memorized during a step d.
• a so-called fast learning step f is authorized during which the average of each of the terms ⁇ is calculated, and 2 over the number P of dead centers high taken into account since the beginning of the process.
• This mean value of the terms ⁇ -, and 3 2 will be used to calculate the engine torque during the following top dead centers, during the engine acceleration phases.
• step a it is checked whether the rapid learning of the terms / 3 1 and ⁇ 2 has already been carried out (step g), in which case the calculation of the gas torque means C • is made from the two appropriate terms ⁇ l e * " ⁇ 2m corres P is ing the two half-turns (step h), to be then operated in an engine control strategy, for example (step i).
• step e if the serial number of the top dead center pmh considered is less than the threshold P (step j), the terms ⁇ ⁇ and 2 calculated in step c are not taken into account for the calculation engine torque as long as pmh is not equal to P, whether the vehicle is at the end of the production chain with a first electronic computer or it is in the service life with a new computer.
• This method of calculating the torque of a heat engine, correcting the defects of the target can be advantageously used in all engine control strategies based on the analysis of the torque, such as the diagnosis of bad combustion or the recognition of the order of appearance of combustion in the different cylinders for the optimization of the controlled electronic injection.
• this calculation method which has just been described in the context of a four-cylinder engine is applicable to any engine regardless of the number of cylinders, the work period is no longer then the U-turn but the interval during which combustion takes place.

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

Applications Claiming Priority (3)

Publications (1)

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• 1996
  • 1996-12-27 FR FR9616140A patent/FR2757945B1/fr not_active Expired - Lifetime
• 1997
  • 1997-12-12 JP JP52967298A patent/JP2001511888A/ja active Pending
  • 1997-12-12 WO PCT/FR1997/002280 patent/WO1998029718A1/fr not_active Application Discontinuation
  • 1997-12-12 US US09/331,194 patent/US6389363B1/en not_active Expired - Fee Related
  • 1997-12-12 AU AU54890/98A patent/AU5489098A/en not_active Abandoned
  • 1997-12-12 EP EP97951317A patent/EP0948739A1/de not_active Withdrawn

Non-Patent Citations (1)

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