FR2787511A1 - METHOD AND DEVICE FOR EQUALIZING THE TORQUES OF EACH CYLINDER OF AN ENGINE - Google Patents

Abstract

Method for equalizing the contributions of the different cylinders of an internal combustion engine to its torque, characterized in that at least one measurement of the individual contributions of the different cylinders to its torque is determined, and it is brought to a regulator, and the output of the regulator exerts an influence specific to each cylinder on the filling of this cylinder with fresh air or gas.

Description

STATE OF THE ART The present invention relates to a method for

  equalize the contributions of the different cylinders of a mo-

  internal combustion torque to its torque.

  The starting point of the invention is an internal combustion engine with a variable stroke of the valve

  of admission constituted in such a way that by means of its posi-

  tion (zero full opening) a command of the motor load can be free from throttling. In addition or

  alternatively one can also start from a variable duration of

the inlet valve.

  An order of this type from an Otto cycle engine

  without throttle valve is known from document EP-

  433 632. The known order provides, inter alia, durations

  opening of the intake valve specific to each cylinder

  dre, predetermined according to a position of the accelerator pedal and the engine speed. Of

  this way we can compensate for differences due to

  construction problems in the air supply. Consequently, we have to get all the active cylinders to suck

  a substantially equal amount of air and fuel mixture

  rant, so that we have a very even distribution

  of the couple and as low an emission as possible of

  pollutants for all cylinders.

  The object of the invention is to further improve the stability of the running of internal combustion engines having

  individual valve control per cylinder.

  To solve this problem, the present invention relates to a method of the type defined above, characterized in

  what we determine at least one measure of the contributions

  of the different cylinders to its torque, and we

  brings it to a regulator, and the output quantity of the regulator

  tor exerts an influence specific to each cylinder on the

  filling this cylinder with fresh air or gas.

  According to other characteristics of the invention: * the output quantity of the regulator exerts an influence on the operation on opening of at least one of the valves of the individual cylinder; r TIi î * the opening operation is influenced by means of a variation of the stroke and / or the opening time of the valve; * in the case of an intervention taking place on a given cylinder, the filling of the other cylinders is influenced in the opposite direction, so that the total torque delivered by the internal combustion engine is modified as little as possible; * in addition to interventions on filling on

  influences the supply of fuel

  pre to each cylinder, so that the composition

  of the air and fuel mixture that burns in the cylinder

dre if possible does not vary.

  Another object of the invention is to reduce

  more emission of pollutants.

  The invention is based on the observation that in addition

  filling differences due to the con- dition conditions

  truction, the clearance of the intake valves according to their

  aging and manufacturing tolerances may

  drag different amounts of different fill

  rents cylinders of an internal combustion engine. These filling tolerances lead to a metering

  identical fuel for each cylinder to contribu-

  different torques per cylinder and have been shown

  in the lower region of the rotational speed in particular

  tie in slow motion as a source of instability in walking

of the internal combustion engine.

  According to other characteristics of the invention: * the measurement of the contributions of the different cylinders to its torque is determined on the basis of an exploitation of

  the instability of the running of the internal combustion engine

  dull; * the measurement of the contributions of the different cylinders to its torque is determined on the basis of the pressures detected

  in the combustion chambers specific to each cylinder.

  The present invention also relates to a dis-

  positive electronic control used to equalize con-

  contributions of the different cylinders of an internal combustion engine to its torque, characterized in that the

  command determines at least one measure of the contributions

  dividuals of the different cylinders to its torque and form from there an output quantity, which exerts an influence specific to each cylinder on the filling of at least one cy-

line in fresh air or gas.

  According to the invention the filling tolerances are detected by means of an exploitation of the stability or

  from the instability of walking, they are brought to a regu-

  reader and they are compensated by means of an intervention

  of the regulator, specific to each cylinder, on the

  opening valves. The invention can be based on a signal detection and reprocessing system to exploit the instability of the engine running. This

  already exists in the case of internal combustion engines

  to make a diagnosis on board the fuel misfires

  tion. Advantages The comparison of the filling tolerances due to the manufacturing conditions, during the operation of the internal combustion engine, increases in this

  point the space needed to build the varia-

  intake valve ble. This can lead in a way

  advantageous to a more economical construction.

  The use of detection and exploitation

  tion of the instability of the running of the engine, which already exists to detect misfire, allows to realize

  the invention with a low additional cost.

  A configuration of the invention makes it possible to have

  compensation for filling tolerances for

  tributions compensated for the torque by keeping a desired average lambda value constant of the air mixture and

  of fuel in the different cylinders.

  The present invention will be described below in more detail on the basis of embodiments, shown in the accompanying drawings, in which:

  * Figure 1 shows the technical environment of the invention.

  tion, * Figure 2 shows the different operations at the opening of internal combustion engine valves and, * Figure 3 discloses a schematic diagram as an exemplary embodiment of the method according to the invention. The reference 1 represents an internal combustion engine with a combustion chamber 2, an injector 3, an intake valve 4, an adjusting member 5 of the valve

  intake, an exhaust valve 6, a re-

  fitting 7 of the exhaust valve, an inlet pipe 8, a throttle valve 9, a sensor 10 for the angle alpha of the throttle valve, a mass measuring device

  air sensor 11, a pressure sensor 12 in the intake pipe

  mission, an engine temperature detector 13, a

  rotational speed sensor or an induction sensor 14, a wheel angle sensor 18 with marks 19 and segments 20 and the lambda probe 15 in the exhaust pipe

  16, as well as an electronic control system 17. The system

  electronic control unit 17 retreats the signals shown

  sensed as a function of the suction air mass ml, the opening angle of the throttle valve alpha, the pressure p in the intake pipe, the engine temperature tmot, the rotation speed n and the lambda composition of the air and fuel mixture to send signals from

  control of the internal combustion engine, for example lar-

  ti impulse boosters for fuel injection,

  ignition, and others. In the representation of FIG. 1, the control device also delivers signals EVS and AVS, which determine the operations at the opening of the valves 4 and 6 of the engine. The concrete realization of

  actuation of the valves, whether hydraulically

  that, mechanical, individual or in group, is not decided

  sive. It is essential that the control system can

  set different operations when opening the supports

  admission popes. Figure 2 shows examples of functions.

  different operations at the opening with a representation

  the VH stroke of the valve as a function of position an-

  crankshaft shaft gular (angle of rotation below

  the crankshaft).

  dashed lines have a stronger choking effect on

  the air which enters and achieves a more reduced filling of the cy-

  lindre. According to a preferred embodiment, the walking instability is assessed by exploiting the course in

  the time of rotation of the crankshaft or the

  cam breeze. To detect the course over time, an angular zone of rotation 20 of the shaft is associated with a determined zone of the movement of the piston in each cylinder.

  of the crankshaft, designated as a segment. The segments are ma-

  serialized for example by marks 19 (teeth) on a

  tone wheel 18 coupled with the crankshaft.

  The rotational movement of the tone wheel 18 coupled with the crankshaft 18 is converted using

  of the angular detector 14, produced in the form of a detector

  inductor into an electrical signal, whose periodi-

  cited constitutes an image of the periodic passage of the marks in front of the angular detector. The time which elapses between an ascent and a descent of the signal level consequently corresponds to the time during which the crankshaft continued to rotate on an angular zone which corresponds to the dimension of a location. These time periods are restated

  in the control device 5, produced in the form of an or-

  computer, to get a measure of the engine instability

  internal combustion. The time ti, which corresponds to a seg-

  ment, during which the crankshaft describes an area

  angular with index i, is already a measure of the in-

  stability of the internal combustion engine. Less the times which correspond to the segments deviate from each other

  others, the more the engine runs, the more its instability

walking tee is small.

  As an alternative to this time use, we

  may have frequency operation. In the case of con-

  regular tributions to the couple the rotational movement of

  the crankshaft of a four-stroke engine is peri-

  dique with the period P equal to the quotient of the angle of the ar-

  bre of the crankshaft (KWW) of 720 by the number of cylinders.

  When, for example, a cylinder systematically delivers too low a torque, this leads to periodic braking of the

  rotational movement of the crankshaft with the

  riode of two rotations of the crankshaft, that is

  say of 720 KWW. Unequal contributions to torque are therefore delivered by fractions of higher frequencies.

  lower than the ignition frequency in the frequency spectrum

  of the rotation of the crankshaft. This can be determined by frequency analysis. The occurrence of these additional low frequency fractions indicates

  in this way unequal contributions from couples.

  The two methods each deliver, according to its operating cost, information selective by cylinder or non-selective, on the running instability of the combustion engine.

internal.

  In the case of selective information by cy-

  lindre we can determine which cylinder contributes

  less or more than the average value of all cylinders.

  This is shown in Figure 3 as an example of implementation: during a step 3.1 training takes place

  of a mi measure for filling a cylinder with the

  dex 1. For example, this takes place by measuring the time corresponding to a segment for the time of the explosion in the cylinder with the index i. Extended segment time Ti is caused by a relatively large torque mk and signals

  this way a relatively large filling of the cylinder.

  In this case the letters k and i number cycles of allu-

  mage or cylinders. Alternatively we can also detect the

  filling by means of pressure in the

  bustion. Both the pressure in the combustion chamber

  that the time corresponding to a segment allows to re-

  refer to the torque which determines the walking stability of the mo-

internal combustion engine.

  During a step 3.2, an average value of the measurements mi, specific to each cylinder, is formed for the filling of the different cylinders. The average value

  mquer is used in steps 3.3 or 3 4 as a comparison criterion

  sound to detect deviations specific to each cylinder. If, for example, the torque of cylinder i increases, the query is answered in the affirmative during step 3.3 and there occurs in step 3.5 a reduction in the filling of this

  cylinder. According to the invention this takes place by means of an inter-

  vention in the operation at the opening of the valves of this cylinder. For example, the operation at the opening VH of the intake valve of this cylinder varies in FIG. 2

  from the solid line to the line shown in dashes.

  If on the other hand, in step 3.4, a

  ple which has decreased is that instead of step 3.6 a variation

  operation when opening in dashed direction

  from operation to full line opening, to increase

ter the filling.

  Advantageously for a cylinder when

  the variation of the operation on opening the operation-

  the opening of the other cylinders varies in the opposite direction

  milk in such a way that the total filling of the combustion chambers of the engine added for all the cylinders does not

  not vary. See steps 3.6 and 3.7 for this.

  In other words: if for example a cylinder

  delivers more torque than other cylinders, filling it

  sage decreases and that of the other cylinders increases, so that the total torque delivered by the cylinders if

possible does not vary.

  The increase in the filling of other cylinders

  dres, as the decrease in the filling of one of the cylin-

  dres, serves among other things to calibrate the engine torque.

  In addition, it must also lead to

  constant overall weight of the internal combustion engine. To this is added the advantage that the engine speed is not changed by the equalization interventions. This

  is represented by steps 3.7 and 3.8.

  Advantageously takes place in parallel with

  interventions in valve control an intervention

  fuel metering specific to each cylinder.

  In cylinders whose filling is reduced, takes place

  a decrease in the amount of fuel to be dosed. The quan-

  The fuel quantity for the other cylinders is increased so that the overall quantity of fuel to be dosed on all the cylinders does not vary. Added to this is the advantage that the lambda value does not vary in the exhaust gases.

  due to equalization interventions.

  In the case of the process specific to each cylinder we try by a repetitive increase and decrease

  and alternating filling specific to each cylinder of improvement

  the overall running stability of the internal combustion engine

  dull. As a measure of this walking stability, the amplitude of the segment oscillations is taken into account, for example.

of measured time.

  For example in the case of a voluntary cylinder-

  ment chosen, one can undertake on a trial basis an

  Take care when filling it and then use the ensuing reaction on the stability of the step. The

  reaction of gait instability to a first se-

  quence of modification provides a signal allowing to know if the selection of the cylinder and the direction of the variation led to the objective. If the gait stability has not improved, it is because the variation has been made retrograde: in other words, we re-adjust the parameters that we

  used before the equalization interventions for the com-

  valve control and fuel metering.

  If on the other hand the walking stability has been improved

  improved by the equalization interventions, the new parameters of the valve control and of the fuel metering for the considered operating point of the internal combustion engine are then stored in memory, in order to have them immediately upon starting. next from the same point of

operation.

  In this way an adaptation takes place, i.e.

  say an adjustment of the valve control times to

  modified operating conditions.

  The iterative process can consist of a ma-

  such that the coefficient is maintained as well

  lambda constant that the idling speed con-

aunt too.

- - T1I

  The storage of optimized control times adapted to the modified operating conditions can

  be performed for both processes. In other words: by using the invention in the form of a method of adapting

  tion, we adjust the idle and close to idle correction values specific to each cylinder, to replace

  wrinkling during the engine idling phases, and they are stored in a non-volatile memory. A modified valve clearance is an example of a modified operating condition.

X1 -11

Claims (9)

R E V E N D I C A T IONS   1) Method for equalizing the contributions of the different cylinders of an internal combustion engine to its torque, characterized in that at least one measurement is determined of the individual contributions of the different cylinders to its torque, and it is brought to a regulator, and the regulator output quantity   exerts an influence specific to each cylinder on the filling   wise of this cylinder in fresh air or gas.   2) Method according to claim 1, characterized in that the output of the regulator has an influence on the operation at the opening of at least one of the valves of the individual cylinder.   3) Method according to claim 2, characterized in that the opening operation is influenced by means of a variation of the stroke and / or the duration of opening of the valve.   4) Method according to one of the preceding claims, characterized in that   in the case of an intervention taking place on a cylinder   finished, the filling of the other cylinders is influenced in the opposite direction, so that the torque delivered in total   by the internal combustion engine is as little as possible dified.    ) Method according to one of the preceding claims,   characterized in that, in addition to the filling operations, there is an influence on the fuel supply specific to each cylinder, so that the composition of the air mixture   and fuel that burns in the cylinder if possible will not not laugh. he   6) Method according to one of the preceding claims,   characterized in that the measurement of the contributions of the different cylinders to its   torque is determined on the basis of an exploitation of the   stability of the internal combustion engine.   7) Method according to one of the preceding claims,   characterized in that the measurement of the contributions of the different cylinders to its torque is determined on the basis of the pressures detected   in the combustion chambers specific to each cylinder.   8) Electronic control device used to equalize   the contributions of the different cylinders of a   internal bustion of its couple, characterized in that   the control system determines at least one measurement of the con-   individual tributions of the different cylinders around it   ple and form from there an output quantity, which   exerts an influence specific to each cylinder on the filling   at least one cylinder in fresh air or gas.   9) Electronic control device according to the claim tion 8, characterized in that   the output quantity influences the function   at the opening of at least one individual cylinder valve duel.   10) Electronic control device according to the claim   tion 8, characterized in that the opening operation is influenced by means of a variation in the stroke and / or the duration of the opening of the valve. -T Tir-,