FR2764942A1 - SYSTEM FOR IMPLEMENTING AN INTERNAL COMBUSTION ENGINE IN PARTICULAR OF AN ENGINE EQUIPPED WITH A MOTOR VEHICLE - Google Patents

Abstract

Method for implementing an internal combustion engine fitted in particular to a vehicle according to which the fuel is injected directly at a pressure (prail) into a combustion chamber of the internal combustion engine, and according to which the pressure (prail) is measured acting on the fuel, characterized in that the mass of fuel to be injected is determined at the time of injection from the pressure (prail) acting on the fuel during the injection.

Description

The present invention relates to a method of operating a motor with

  internal combustion fitted in particular to a vehicle according to which the fuel is injected directly

  at a pressure (prail) in a combustion chamber of the mo-

  internal combustion, and according to which the pressure is measured

  sion (prail) acting on the fuel.

  The invention also relates to an internal combustion engine, in particular of a motor vehicle, comprising at least one combustion chamber with an injector, the fuel car being injected directly by this injector into the combustion chamber, a pump generating a pressure

  (prail) for fuel applied to the injector and a cap-

  pressure sensor for measuring the pressure (prail) acting on the fuel and a control device for controlling and / or regulating the quantities influencing combustion of the

  fuel in the combustion chamber.

  Such a process is known in particular for mo-

  diesel direct injection internal combustion engines

  or gasoline for motor vehicles. In each room

  bre combustion, there is an injector which injects directly-

  fuel under the appropriate pressure in the respective combustion chamber. A pump generates the pressure of the

  fuel to which fuel is supplied to the injectors.

  Among other things, for the dosage of the mass of

  fuel to be injected into the combustion chambers, the pressure

  Fuel consumption at each injection is very important.

  Thus, for example, for the same mass of fuel to be injected, under high pressure, a shorter pulse duration is sufficient than in the opposite case when, with a lower pressure, the respective injector is maintained.

longer in the open position.

  If the pressure acting on the fuel was substantially constant during the duration of the injection, the mass of fuel to be injected could be deduced directly from the duration of the injection. Conversely, it would also be possible for a substantially constant pressure, to calculate beforehand the injection time necessary for

  inject a certain mass of fuel.

  On the basis of the rather small volume of fuel on which the pressure acts, this pressure varies however during the duration of the injection. Thus, the pressure acting on the fuel decreases after the opening of the injector and it does not rise again until after the closing of the injector.

  The pressure sensor measures this pressure

  reliable generated by the pump and acting on the fuel.

  The difficulty is that on the one hand the pressure

  acting on the fuel during the respective injection,

  laughs as has been indicated and is not known beforehand and moreover, this pressure must be taken into account for the metering of the mass of fuel which must be injected with this injection. This problem has been solved until now by using the pressure acting on the fuel during the metering to measure the mass of fuel for the next injection.

  last previous injection. However, this process is not pre-

  cis because of the system and thus leads to faults at the mo-

injection.

  The object of the present invention is to remedy

  these drawbacks and intends to develop a per-

  putting a more precise dosage of the fuel mass to

eject.

  This problem is solved by a process of the type

  finish above, characterized in that the mass of fuel to be injected is determined at the time of injection from the pressure (prail) acting on the fuel during injection. This problem is also solved in the case of a

  internal combustion engine of the type defined above, charac-

  in that the control unit determines the mass of

  fuel injected during injection using pressure

  sion (prail) acting on the fuel during injection. In other words, the problem is solved by determining during the injection, the mass of fuel to be injected from the pressure acting on the fuel at

during this same injection.

  The pressure acting on the fuel is thus measured during the same injection to use this measurement directly, to determine the mass of fuel that must be injected. Thus, from the pressure, the corresponding mass of fuel is determined directly and influenced

  this one. The injection operation, in particular the mass of the

  burant which must be injected is influenced according to the invention by measuring the pressure acting on the fuel, by

real-time monitoring.

  This considerably increases the pre-

  cision of the mass of fuel to be injected. General faults

  hitherto resided by the variations in the pressure acting on the fuel are avoided by this method according to the invention by working in real time. As a result, the engine

  internal combustion turns much more calmly, that is

  say it generates fewer shakes than would cause

  improperly injected fuel masses. In or-

  the invention makes it possible to reduce the consumption of

  rant and reduce harmful exhaust fumes.

  According to an advantageous development of the invention,

  the mass of fuel to be injected is determined by an injection

  tion from the variation in pressure applied during

  during fuel injection. We thus observe the variation of the pressure acting on the fuel and as a function of this, we influence if necessary the mass of fuel that must be injected. This means makes it possible to directly detect the pressure variation during the duration of the injection and

  to use this information for real-time injection.

  According to an advantageous development of the invention, from the pressure acting on the fuel during the injection, it is concluded that the mass of fuel to be injected is too large and / or that it is too low and / or that it there is a mass of injected fuel missing. If during an injection, the pressure acting on the fuel varies only slightly or not at all, it is deduced therefrom that the mass of fuel to be injected is too low or that there has been no injection. The coarse monitoring described above of the pressure in real time thus makes it possible to detect an injection fault. It is thus possible very prematurely, to oppose a recognized fault by appropriate means or to generate adequate error signals for example for the driver of the vehicle.5 According to an advantageous development of the invention, the mass of fuel injected during the injection is calculated from the maximum variation of the pressure acting on the fuel during the injection. This maximum variation of

  the pressure is determined in a particularly sim-10 pie manner which makes it possible to calculate very simply and very quickly the mass of fuel which results therefrom.

  It is therefore particularly advantageous to cal-

  calculate the mass of fuel according to a linear function and / or

  integration and / or using a character field

  ques and / or using a root function. The selection

  of the respective calculation process can be done according to the pre-

  desired cision and / or available calculation time.

  According to another advantageous development of the invention, for the mass of fuel to be injected into the combustion chamber using an injector, the mass of fuel injected during injection is calculated from the first partial mass of fuel, during opening

  of the injector, the second partial mass of fuel

  in the open state of the injector and the third mass through

  fuel during the closure of the injector. By

  this division of the entire mass of fuel to in-

  ject into three partial fuel masses, a particularly precise and rapid calculation of the entire fuel mass is carried out. In addition, this allows for

  the calculation in a very particular way of the conditions li-

  special moths during the respective operating states

injector.

  According to an advantageous development of the invention, the first partial mass of fuel is calculated from the pressure acting on the fuel at the time of the start.

  from the opening of the injector and / or the second and the third

  fifth partial mass of fuel from pressure

  actually acting on the fuel. In addition, he is

  particularly interesting to use for the calculation of the first of the second and / or the third partial mass of fuel, the functions and the fields of characteristics

or others.

  According to another advantageous development of the invention, the current injection is stopped when the mass of fuel injected during the current injection exceeds a predetermined threshold. Thus, the mass of fuel to be injected, calculated using the pressure acting on the fuel,

  is compared to a predetermined threshold. We can then see if the current fuel mass injected has already exceeded the

  their threshold and at this time we stop the injection in progress. Correspondingly, if it can be foreseen that the mass of fuel to be injected risks being directly reached, on15 exceeds the threshold. This means limits the mass of fuel injected to the predetermined threshold. This already offers the indicated advantages of a quiet operation of the internal combustion engine and a reduction in fuel consumption and the emission of polluting gases. According to another advantageous development of the invention, previously calculates the time at which the

  mass of fuel injected by the current injection, exceeding

  would be a predetermined set value; as a function of this instant, the current injection is stopped. This corresponds to a forecast to assess the mass of fuel to be injected. In this way, it is possible to calculate precisely beforehand the instant at which the mass of fuel to be injected corresponds to the set value.

  to stop the injection at this time.

  It is particularly advantageous to carry out the method according to the invention in the form of an electrical memory means provided for an apparatus for controlling an internal combustion engine, in particular a motor vehicle. For

  this, the electric recording medium contains a pro-

  gram to be run in a calculator, including

  ment a microprocessor and to execute the method according to the invention. In this case, the invention is carried out by a program stored in an electric memory so that this recording medium provided with the program is suitable

  like the invention to execute the process. Other characteristics and applications of the invention will appear on reading the description of the

  embodiment shown schematically in the accompanying drawings in which:

  - Figure 1 is a block diagram of an exemplary embodiment

  sation of a system according to the invention for implementing

  an internal combustion engine with several combustion chambers

  bustion, in particular equipping a motor vehicle, - Figures 2a-2c are schematic timing diagrams of signals produced in the system of Figure 2,

  - Figure 3 shows a block diagram of an example of a

  reading of a method according to the invention for the implementation

work of the system of figure 1.

  Figure 1 shows a fuel supply system of an internal combustion engine intended to equip

  a motor vehicle. The internal combustion engine has

  three cylinders and thus four combustion chambers. This mo-

  internal combustion tor corresponds to an embodiment in which fuel, in particular petrol is injected

  directly into the combustion chambers.

  The fuel is supplied by a pump 2 from a tank 3 through a filter 4, then another pump 5 which takes the fuel in a pressure chamber 6. The

  pumps 2, 5 generate a pressure in the pressure chamber 6

  relatively high pressure applied to fuel. A pressure control valve 7 and a pressure sensor 8 are connected to the pressure chamber 6; this pressure sensor

  measures the fuel pressure in chamber 6.

  The pressure sensor 8 generates an electrical signal called

  by convention (prail) which corresponds to the pressure measured.

  This signal is transmitted by line 9 to a communication device.

  electrical control 10. The pressure control valve 7 and the pressure sensor 8 make it possible to regulate the pressure

  in the pressure chamber 6, i.e. the pressure acting

  fuel on the control unit 10, on a

  high and substantially constant output value.

  The control device 10 can be constituted for example by a programmable microprocessor comprising

  memories and other appropriate components; it can be the microprocessor equipping the vehicle. The control device 5 10 thus receives the signals necessary for the execution of the program.

  transferred among others those of the respective sensors, for example of the pressure sensor 8; from there it generates the signals

  necessary for the execution of the process to order for example-

  full of actuators such as those controlling the injectors 11

  or the pressure control valve 7.

  Four injectors 11 are connected to the pressure chamber 6. Each injector 11 is directly associated with a combustion chamber of the engine. When the injectors 11 are closed, they separate the pressure chamber 6 from the combustion chamber. The injectors 11 are connected to the control device 10 by electrical lines 12. To control one of the injectors 11, the control device 10 generates an electrical signal (ti) which controls the opening of

  the corresponding injector 11. The duration of the signal (ti) corresponds to

  pond to the injection time during which the fuel in the pressure chamber 6 is injected by the injector 11 into

  the combustion chamber of the internal combustion engine.

  Figure 2a shows the signal (ti) and the signal (prail) as a function of time (t). At the start of the injection, i.e. before time T1, the pressure (prail) in the pressure chamber 6, i.e. on one side of the injector

  11 is at the starting value, substantially constant and high.

  vee. The pressure in the combustion chamber, on the other

  side of injector 11 is less than pressure (prail).

  If now the injector 11 is opened at time T1 by the signal (ti), the pressure (prail) drops. This is due to the fact that the pressure (prail) can relax in the combustion chamber through the injector 11, which is open. Overall, the pressure (prail) drops according to FIG. 2a, from the value Ap to a minimum value. Then there is a balancing of the pressures of the pressure chamber 6 and of the combustion chamber which then leads to the pressure (prail) increasing slowly again. When the injector 11 is closed at the instant T2, the pressure (prail) continues to increase until it again reaches a high and substantially constant starting value. The mass of fuel injected into the corresponding combustion chamber during this operation, from the pressure chamber 6 by the injector 11 depends on the pressure (prail). The higher the pressure acting on the fuel, the greater the quantity of fuel passing from the pressure chamber 6 into the combustion chamber 10 while the injector 11 is open. The reverse is also true. In addition, the mass of fuel injected depends on the injector 11, in particular on its dynamic behavior on opening and closing. Under these conditions, it may be necessary to measure beforehand the dynamic behavior on opening and closing of the injectors 11 used. This makes it possible to determine beforehand how the pressure (prail) can vary correctly during an injection. In particular, it is possible to determine beforehand from what value Ap and the pressure (prail), this pressure can drop during an injection. These values can be

  determined and stored in memory as already indicated before-

  ble for the different injectors 11 and the different states

  of the internal combustion engine.

  During engine operation, there is for example a signal profile (prail) like the one appearing

  in Figure 2b. This figure shows that the injections suc-

  stops cause different variations in pressure (prail). In particular we arrive at values Apl, Ap2,

  Ap3, different. This is mainly due to the dy-

  different from the various injectors 11. The pre-

  alables carried out on the injectors nevertheless allow as already indicated, to know the foreseeable variations of the pressure (prail) with each injection. This is why, it is possible during operation, to compare the foreseeable evolution of the pressure (prail) with the current evolution of the pressure (prail) in real time. If the predictable curves essentially correspond with the current curves, we can conclude that the injection

is correct.

  If this comparison shows, however,

  important, we can deduce that there is an injection fault. Figure 2c gives examples. In this figure, the normal pressure curve (prail) during an injection has been represented under the reference 13. A pressure curve (prail), practically unchanged carries the

  reference 14. This allows to conclude that the planned injection10 for the moment (ti) has not occurred. A slight variation

  tion of the pressure (prail) is characterized by the reference 15. From the curve, by comparison with the foreseeable curve it can be concluded that in this injection, there is

  too little fuel injected into the combustion chamber

  tion. In addition, a significant variation in pressure

  (prail) is designated by the reference 16. This makes it possible to

  closes by comparison that during this injection, too much

fuel has been injected.

  If in this way we see that despite a

  general (ti) there has been no injection, a corresponding error program can be started by the control unit to oppose the fault or indicate a fault to the driver of the vehicle. If the internal combustion engine has an output stage for controlling the injectors 11 with a voltage take-up, according to which for example two injectors 11 are always controlled in common, by comparison

  we can determine (if there is a corresponding curve

  corresponding to reference 14) if only one of the two injections

  teurs 11 is defective or if (if the curve occurs

  always in pairs) the associated power stage is defective

  killer. Measuring the Ap value during an injection

  also allows calculation of the current fuel mass-

  ment injected. It is possible to combine the value Ap for calculating the fuel mass in a linear fashion with a coefficient representing in particular the dynamic and / or hydraulic properties of the fuel supply system 1, that is to say for example the speed engine rotation at

  internal combustion, the load applied to the combustion engine

  internal or other. This combination can also be done using a characteristics field. In addition, during the combination, one can integrate the value Ap as a function of time or form the root of the value Ap, then integrate. On the basis of this calculation of the mass of fuel currently injected, we can then act in real time on

  fuel injection into the engine

  internal bustion. This will be described below using the fi

gure 3.

  Figure 3 shows an implementation process

  of the fuel supply system 1 of FIG. 1.

  After the signal (ti) corresponding to figure 2a, let go

  at the instant Tl in its tilted state, the pressure (prail) exists

  both in the pressure chamber 6 and thus the pressure acting

  Fuel health is measured at short time intervals. The first measured value, i.e. the pressure at time T1 when the injector 11 is open, is called

  in figure 2 (prail.EV-open). The values measured in-

  next, carry the current reference (prail).

  The value (prail.EV-open) is supplied from a characteristics field 17. From this value, the first partial mass of fuel is calculated, associated with the time interval during which the injector 11 changes to

  its open state. The first partial mass of fuel

  hangs from the pressure (prail.EV-open), prevailing at time Tl when the injector 11 is open. In addition, the first partial mass of fuel depends on the injector 11 as such and in particular on its dynamic behavior on opening. The first partial mass of fuel is

  then available as signal (mkr.EV-open).

  During the time when the injector 11 is static in the closed state, the values (current current) are applied in short time intervals each time at

  a characteristic field 18 which calculates a res-

  pective (mkr). This value (mkr) depends on the pressure

  pective (prail.actuelle) as well as the injector 11 as such, in particular its fluid consumption. The value (mkr) is then integrated for the measured pressures (current), using a feedback loop 19. For this, the sum of the added values (mkr) is always stored in an intermediate way as value (mkrold) to be added again to the next value (mkr). The value (mkrold) corresponds to a second partial mass of fuel which, as indicated, corresponds to the time during which the injector 11 is in the open static state. In addition, the value (current) is provided to a characteristics field 20 which calculates a value

  (mkr.EV-close) as the third partial mass of fuel.

  The value (mkr.EV-close) then corresponds to the mass of car-

  burant which was further injected by injector 11 into the

  combustion chamber, assuming that the injector 11 au-

  was immediately closed. The third partial mass of fuel (mkr.EV-close) is thus associated with the interval necessary for the injector 11 to enter the closed state after the instant T2. This third partial mass of fuel (mkr.EV-close) depends as well as the pressure (current) as well as on the injector 11, in particular on its behavior

dynamic closing.

  From the three partial masses of carbu-

  rant, obtained as described above, we arrive at the overall mass of fuel for which the injection triggered by

  the signal (ti) is injected by the injector 11 into the cham-

  corresponding combustion bre, if the injection has been stopped

immediately.

  According to FIG. 3, the three partial masses of fuel are successively added (mkr.EV-open, mkrold, mkr.EV-close). The resulting total mass of fuel is compared by a corresponding function 21 to a desired, predetermined setpoint (mkr_cons) of the

mass of fuel to be injected.

  Thus, the comparison shows that the mass of car-

  current, calculated, is greater than the con-

  predetermined sign (mkr_cons), we immediately stop the current injection. This is done using the bit (B_EScoupure). This bit controls the signal (ti) to immediately change it to the cut state. It follows that

  the corresponding injector 11 also closes immediately and thus terminates the injection. If, on the other hand, the comparison indicates that the

  their setpoint (mkrcons) is still greater than the mass

  fuel calculated, injection is not stopped

  tee. In this case, one can calculate, beforehand, when the current fuel mass will exceed the set value (mkr_cons) to then stop the injection at this time. This prediction makes it possible in particular to evaluate the mass of fuel which has been injected if after another duration the injection is cut off. If this estimated fuel mass exceeds the set value (mkrcons), the injection can again be stopped immediately with the consequence of a low minimum injection; you can also stop the injection from an additional period with the consequence of a smaller injection; it is also possible to calculate the time after which the injection must be stopped so that the mass of fuel injected corresponds exactly to the value of

setpoint (mkr_cons).

  The invention also relates to an electrical recording medium, in particular a read-only memory for an apparatus for controlling an internal combustion engine for

  a motor vehicle. This memory can contain a pro-

  2 _gram intended for a computing device, in particular a micro-

  processor, to develop and execute the process such as

defined above.

Claims (12)

R E V E N D I C A T IONS   1) Method for implementing an internal combustion engine   dull, especially in a vehicle in which the fuel   rant is injected directly at a pressure (prail) into a combustion chamber of the internal combustion engine, and   lon which the pressure (prail) acting on the car is measured   burant, characterized in that the mass of fuel to be injected is determined at the time of injection from the pressure (prail) acting on the fuel during injection.   2) Method according to claim 1, characterized in that the mass of fuel to be injected at the time of injection is determined from a variation of the pressure (prail)   acting during fuel injection.   ) Method according to claim 1 or 2, characterized in that, starting from the pressure (prail) acting during the injection   on the fuel, we conclude that the mass of fuel injected   is too large and / or that the fuel mass   disconnected is too weak and / or there is a mass defect in fuel injected.   4) Method according to claim 3, characterized in that   we start a fault routine.    ) Method according to one of claims 1 to 4,   characterized in that the mass of fuel injected during the injection is calculated from the maximum variation (Ap) of the pressure (prail)   acting on the fuel during injection.   6) Method according to claim 5, characterized in that the fuel mass is calculated according to a linear function and / or by integration and / or is determined from a field of characteristics and / or is calculated from a root function.   7) Method according to any one of claims 1 to 6,   characterized in that the mass of fuel is injected using an injector (11)   in the combustion chamber and we calculate the mass of car-   fuel injected during injection from a first partial mass of fuel (mkr.EV-open) during the opening of the injector (11), a second partial mass of fuel (mkrold) during the open state of the injector   (11) and a third partial mass of fuel (mkr.EV-   close) while the injector (11) is closing.   8) Method according to claim 7, characterized in that   the first partial mass of fuel is calculated (mkr.EV-   open) from the pressure (prail.EV-open) acting on the fuel at the time of the start of the opening of the injector (11).   9) Method according to any one of claims 7 and 8, characterized in that   we calculate the second and third partial mass of carbu-   rant (mkrold, mkr.EV-close) from pressure   (prail.actuelle) currently acting on the fuel.   10) Method according to any one of claims 7 to 9,   characterized in that to calculate the first, second and / or third   partial fuel mass (mkr.EV-open, mkrold, mkr.EV-   close), we use functions (19) or fields of   (17, 18, 20) or the like.   11) Method according to any one of claims 1 to 10,   characterized in that the current injection is stopped (B_ES_coupure) if the mass of fuel injected during the actual injection exceeds a predetermined set value (mkr_cons)   12) Method according to any one of claims 1 to 10, characterized in that   we calculate beforehand the moment at which the mass of fuel injected during a current injection could exceed a predetermined set value (mkrcons) and in function   tion of this instant, we stop the current injection (B_ES_coupure).   13) Electric recording medium, especially read-only memory for a control device (10) of a combustion engine   internal tion equipping in particular a motor vehicle and containing a program suitable for application with a computing device, in particular a microprocessor, makes it possible to develop and execute a method according to any one of claims 1 to 12.   14) Internal combustion engine, especially for a vehicle   tomobile comprising at least one combustion chamber with an injector (11), the fuel being injected directly by this injector into the combustion chamber, a pump (2, 5) generating a pressure (prail) for the fuel applied to the injector (11) and a pressure sensor (8) for measuring the pressure (prail) acting on the fuel and a control device (10) for controlling and / or regulating the quantities influencing combustion of the fuel in the combustion chamber, characterized in that   the control unit determines the mass of fuel injected   during injection using pressure (prail)   acting on the fuel during injection.    ) Internal combustion engine according to claim 14, characterized in that the control device (10) deduces from the pressure acting on the fuel during the injection (prail) that the mass of fuel injected is too large and / or that the mass of fuel injected is too low and / or that the mass of fuel injected is lacking. 16) Internal combustion engine according to claim 14 or 15, characterized in that   the control unit (10) calculates the mass of fuel   ejected during the injection from a first mass per-   fuel tial (mkr.EV-open) during the opening of the injector (11), a second partial mass of fuel (mkrold) during the open state of the injector (11) and a   third partial fuel mass (mkr.EV-close) during   when the injector is closed (11)