FR2864160A1 - Internal combustion engine controlling method for motor vehicle, involves pumping fuel corresponding to normal and starting modes in fuel manifold which has injectors supplying fuel to cylinders - Google Patents

Abstract

The method involves pumping a fuel corresponding to a normal operating mode of an internal combustion engine, in a fuel manifold (5). The fuel manifold has fuel injectors (10, 15, 20, 25) associated to respective cylinders of the engine for supplying the fuel to the cylinders. A fuel corresponding to a starting mode of the engine is pumped in the fuel manifold. An independent claim is also included for a device of controlling an internal combustion engine.

Description

Field of the invention

  The present invention relates to a method of controlling an internal combustion engine comprising a fuel-operated thermal engine, wherein different fuel types are used for combustion in different modes of operation.

  The invention also relates to a control device of an internal combustion engine comprising a heat engine fed with different fuels provided for the combustion according to the different modes of operation.

  STATE OF THE ART Some countries are increasingly favoring the use of a flexible or environmentally friendly fuel for gasoline engines. In addition to the gasoline used, it is also possible to use ethanol. The basic problem with this fuel is its poor cold starting ability when the fuel has a very high alcohol content. The evaporation of such a fuel to form an air / fuel mixture, fuel, is then no longer sufficient. One solution to this problem is to inject in addition to gasoline using a separate starter fuel; with a simple pump it is possible, by a pipe and a nozzle, to inject fuel at the throttle flap into the intake pipe of the internal combustion engine operating with starting fuel. For this purpose a small fuel tank is provided which contains pure gasoline as a starter fuel. The starter fuel injection is only activated at the start of the internal combustion engine when the engine is warm, that is to say at an engine temperature below a value of between 15-20 C. The difficulty in this solution is the precise dosing of the starter fuel. The setting of the fuel pressure and the pressure itself depend strongly on the supply voltage. Another difficulty is the regular distribution of starting fuel between all the cylinders of the internal combustion engine. By supplying the starter fuel centrally at the throttle flap to the intake duct, low air flow is achieved, easily at an uneven distribution of starting fuel between the cylinders. In systems equipped with a dual-function coil, there is also the risk of explosion in the intake pipe because the entire intake pipe is enriched with a mixture of fuel and gasoline.

  DESCRIPTION AND ADVENTURE OF THE INVENTION The present invention relates to a process of the type defined above, characterized in that the fuel corresponding to a first type of fuel is pumped for a first mode of operation in a fuel distribution ramp, this ramp being equipped with at least one fuel injector, for supplying fuel to the internal combustion engine, and the fuel corresponding to the second type of fuel is pumped for a second mode of operation in the fuel distribution ramp.

  The invention also relates to a device of the type defined above, characterized in that a first fuel pump pumps the fuel corresponding to a first type of fuel for a first mode of operation, in a fuel distribution ramp equipped at least one fuel injector that supplies the fuel to the engine, and a second fuel pump pumps the fuel corresponding to a second fuel type for a second mode of operation in the fuel distribution manifold.

  The method and the device for managing an internal combustion engine equipped with a heat engine operating with fuel as defined above has the advantage that the fuel corresponding to the first type of fuel for a first time. mode of operation is pumped into a fuel distribution ramp equipped with at least one injector which supplies the fuel to the heat engine or internal combustion engine and that the fuel corresponding to the second type of fuel for a second mode of operation is also pumped into the fuel delivery ramp. In both modes of operation the fuel of each type of fuel can be accurately metered. If one of the two situations or modes of operation is the starting mode of the internal combustion engine, the result is a low gas emission at the start of the internal combustion engine. An uneven distribution of fuel between the different cylinders in both operating modes is avoided. There is also no increase in the risk of explosion of the intake duct because in both operating modes, the fuel is injected directly into the different cylinders or through the intake duct. near the intake valves. In addition, the use of a common fuel distribution rail to provide the fuel for different types of fuel is a simple and economical solution.

  It is particularly advantageous that while the fuel corresponding to the second type of fuel is pumped into the fuel distribution manifold, a nonreturn valve equipping a connecting line between the first fuel pump, which pumps the fuel corresponding to the first type of fuel in the fuel distribution manifold and that the fuel distribution manifold is short-circuited by a bypass valve. This ensures that the fuel of the first type of fuel can return to the first fuel tank from the fuel delivery ramp, as long as the fuel of the second type is pumped into the fuel distribution manifold. Thus the fuel of the second type of fuel can drive the fuel of the first type of fuel in the second mode of operation, to evacuate the fuel distribution ramp.

  It is particularly advantageous further that the amount of fuel corresponding to the fuel of the second type, and which is pumped into the fuel distribution manifold in the second mode of operation, is defined according to the operating parameters of the combustion engine. internal, according to the operating parameters of the internal combustion engine is determined at a time at which the fuel pumped into the fuel distribution manifold during the second mode of operation and corresponding to the second type of fuel is consumed, and until that moment the operating parameters of the internal combustion engine are set to operate the engine with the second type of fuel, and thereafter the operating parameters of the engine are set to operate the engine with the first type of fuel. This ensures that for each of the two modes of operation or for each of the two types of fuel, the internal combustion engine operates with the associated operating parameters, avoiding any malfunctioning of the engine.

  Preferably the amount of fuel corresponding to the second type of fuel which has been pumped in the second mode of operation in the fuel distribution manifold is determined according to the supply voltage and the control duration of the fuel. second fuel pump, and / or the time at which the fuel corresponding to the second fuel type pumped in the fuel distribution manifold for the second mode of operation has been consumed, as a function of the speed of rotation of the fuel pump; motor (engine speed) and the control time of at least one injector.

  Advantageously, the fuel corresponding to the second type of fuel is pumped into the fuel distribution manifold via a second fuel pump.

  Drawings The present invention will be described in more detail below with the aid of an exemplary embodiment shown in the accompanying drawings in which: - Figure 1 shows a fuel supply system of a combustion engine Figure 2 shows a flowchart for describing the operation of the method and apparatus of the invention.

Description of the embodiment

  According to FIG. 1, reference numeral 1 denotes an internal combustion engine whose figure only shows the fuel supply system. The fuel supply system corresponds to a device according to the invention equipped with a fuel distribution rail 5. Four injectors 10, 15, 20, 25 are connected to the fuel distribution rail 5. These injectors each fuel is associated with a cylinder of the internal combustion engine not shown in Figure 1 to inject fuel. It can also provide more or less than four injectors. The fuel delivery ramp 5 receives, via a first connecting line 50, a first type of fuel from a first tank 60. For this purpose, a first fuel pump 30 is provided which takes the first type of fuel from the first fuel tank. fuel 60 to supply it to the fuel distribution rail 5 by the first connecting line 50.

  According to FIG. 1, the first connecting line 50 comprises a first nonreturn valve 40 preventing the return of fuel to the first fuel pump 30. FIG. 1 shows in addition to a bypass valve 55 installed in a pipe This bypass line bypasses the first valve or non-return valve 40. There is also provided a second fuel pump 35 which draws fuel corresponding to a second fuel type from a second fuel tank 65 by a supply line 85 opening into a second connecting line 75; by this second connecting line 75 is pumped into the fuel distribution manifold 5 preferably at another place and in particular at a place opposite to that of the fuel supply of the first type. The second connecting pipe 75 comprises a second nonreturn valve 45 preventing the return of the fuel to the second fuel pump 35. There is also provided a control 70 integrated for example in the form of a program and / or a circuit in the engine control or management of the internal combustion engine 1. The control 70 controls the first fuel pump 30 and that of the second fuel pump 35. The control or engine management 70 command In addition, the control valve 70 controls the four fuel injection valves or injectors 10, 15, 20, 25 to determine the quantities of fuel injected into the various cylinders. The engine may comprise, as indicated, one or more cylinders.

  The fuel corresponding to the first type of fuel is supplied to the fuel distribution ramp 8 at a first end 90 of this ramp 5 via a first connecting line 50; in FIG. 1, the fuel corresponding to the second type of fuel is supplied to the fuel distribution manifold 5 at a second end 95 of the ramp 5 opposite the first end 90 of this fuel distribution manifold by the intermediate of the second connecting line 75. It is advantageous under these conditions that the fuel distribution manifold 5 generally comprises two connections or connections by which the fuel corresponding to one of the two types of fuels can be supplied by a fuel pump corresponding to the fuel distribution ramp 5. The fuel distribution ramp 5 distributes the fuel it receives between the four fuel injection valves or injectors 10, 15, 20, 25, on a regular basis .

  In this example, a first mode of operation corresponds to the normal operating mode of the engine constituting the internal combustion engine 1. In this first mode of operation, the fuel corresponding to the first type of fuel is pumped by the first fuel pump 30 in the fuel distribution manifold 5 and thus it is pumped at the same time to the four fuel injectors or injectors 10, 15, 20, 25. This first type of fuel may be for example a fuel said soft fuel or ethanol. The second check valve 45 prevents the fuel corresponding to the first type of fuel from passing through the second connecting line 75 and the second fuel pump 35 into the second fuel tank 65 to mix therein with the fuel. corresponding to the first type of fuel. The second operating mode of this embodiment is characterized by a starting mode of the internal combustion engine; this mode of operation can for example be chosen for a motor temperature lower than a value between 15 and 20 C. Under these conditions, before starting the first fuel pump 30 during the starting of the internal combustion engine and thus in the second operating mode, during a first predetermined duration, the second fuel pump 35 is started for pumping fuel corresponding to the second type of fuel in the fuel distribution manifold 5.

  The second fuel pump 35 can be started in the event of the engine temperature being below a predetermined value which in this embodiment corresponds to a value between 15 and 20 C, for example after the order a switch indicating the imminent desire to start or even in the case of a motor vehicle, after the opening of a door contact, corresponding to the opening of a door of the vehicle also showing the desire to start quickly. The fuel corresponding to the second type of fuel may be, for example, pure gasoline. The fuel corresponding to the second type of fuel discharges during the first predetermined time the fuel of the first type of the fuel distribution ramp 5. The first predetermined duration is suitable for example to be applied on a test bench; we will choose the first predetermined time, long enough to have enough pure gasoline for starting the engine. If, as shown in FIG. 1, the first non-return valve 40 is mounted in the first connecting line 50, the fuel corresponding to the first type of fuel can not return to the first fuel tank 60 unless the bypass valve 55 is opened by command 70 for a second predefined duration.

  The second predefined period which also allows, for example, an application on a test bench, and for which this second predetermined duration is at most chosen sufficiently large so that the quantity of fuel which is in the front fuel distribution ramp switching on the second fuel pump 35 can return fuel of the first fuel type into the first fuel tank 60 through the bypass valve 55. Only when a sufficient amount of fuel corresponding to the second type of fuel has been pumped for starting the internal combustion engine into the fuel distribution manifold 5 that the second fuel pump 35 will be stopped, the first fuel pump 30 will be turned on and thus the pressure fuel for the supply of fuel corresponding to the first type of fuel will start to climb into the carburettor 5 to operate the internal combustion engine 1 in its first mode of operation which in this example corresponds to the normal operating mode of the internal combustion engine.

  Under the assumptions described, it is possible to start the engine in a defined way with fuel corresponding to the second type of fuel. The use of the fuel distribution manifold 5 thus makes it possible to avoid, even at the start of the engine, an unbalanced distribution of the fuel between the various cylinders of the internal combustion engine and to ensure an accurate metering of the fuel to the various cylinders. In the case of a direct injection of fuel by the injectors 10, 15, 20, 25, in the associated cylinders, it also avoids the explosion in the intake pipe. In the case of injection into the intake pipe, the risk of explosion is not increased compared to systems using only one type of fuel.

  Depending on the supply voltage applied to the second fuel pump 35 during the start-up phase or during engine start-up, and in the case of a vehicle during the start-up phase, that is that is, the voltage of the vehicle battery and the control period of the second fuel pump 35, i.e. the time the second fuel pump 35 is energized, makes it possible to determine Using known calculation methods, the amount of fuel supplied to the fuel distribution manifold corresponding to the second fuel type using an integration method. The battery voltage or the supply voltage and the control time of the second fuel pump are known information from the control 70 insofar as the control of the second fuel pump 35 is provided by the control 70. in addition, depending on the rotational speed of the engine (engine speed) nmot, the internal combustion engine and the control time of the fuel injectors 10, 15, 20, 25, that is to say the duration during which the fuel injectors 10, 15, 20, 25 inject fuel, that is to say the injection time ti determined by known calculation methods, the amount of fuel corresponding to the second type of fuel which has has been consumed after starting the internal combustion engine, using an integration process. The battery voltage or the supply voltage, the control time of the second fuel pump 35, the engine speed (engine speed) nmot and the control time of the fuel injection valves or fuel injectors ) are operating parameters of the internal combustion engine 1. From the quantity of fuel introduced and the quantity of fuel consumed corresponding to the second type of fuel, it is then possible, by means of a comparison operation , determine the instant after the start of the start of the second fuel pump 35, at which time the amount of fuel pumped into the fuel distribution rail 5 corresponding to the fuel of the second fuel type has been consumed. Until this time, the operating parameters of the internal combustion engine 1, such as, for example, the air supply, the fuel supply and the ignition time in the case of a gasoline engine are determined. and other necessary control parameters of the internal combustion engine 1, and depending on the fuel used corresponding to the second type of fuel.

  From this moment which characterizes at the same time the switching between the second mode of operation and the first mode of operation, and with which the first type of fuel is supplied with fuel for the various cylinders, the parameters of and the necessary control variables of the internal combustion engine 1, again according to the fuel used corresponding to the first type of fuel.

  The duration of control of the fuel injectors 10, 15, 20, 25, during the second mode of operation is a known duration of the command 70 because this control 70 ensures the control of the fuel injectors 10, 15, 20 25. By means of a rotational speed sensor equipping the internal combustion engine, a speed sensor not shown in FIG. 1, it is possible to determine in a manner known to a person skilled in the art. , the rotational speed of the engine (engine speed) nmot for the internal combustion engine and transmit this information to the control 70.

  FIG. 2 shows a functional diagram or flow chart describing the progress of the method according to the invention or the operation of the device according to the invention and that by way of example. According to the functional diagram or flow chart of FIG. 2, there is provided a first calculation block 100 receiving as input quantity the control time of the second fuel pump 35 and the supply voltage of the second pump. fuel 35. From these input quantities, the first calculation block 100 calculates the amount of fuel corresponding to the second type of fuel introduced into the fuel distribution ramp 5; this calculation is done for example by an integration method. For this purpose, the control time of the second fuel pump 35 for a given supply voltage is incorporated in a manner known to those skilled in the art. The amount of fuel obtained corresponding to the second type of fuel is transmitted to a comparison element 110. The first calculation block 100 can additionally receive one or more other input quantities which influence the quantity of fuel introduced corresponding to the second type of fuel. fuel; it is for example the temperature of the fuel corresponding to the second type of fuel and for calculating the amount of fuel introduced corresponding to the fuel of the second type, it is customary for the person skilled in the art. There is further provided a second calculation block 105 receiving as input quantity, the injection time ti and the engine speed (motor rotation speed) nmot; according to these input quantities, this block calculates the quantity of fuel corresponding to the second type of fuel, consumed after the start of the internal combustion engine.

  The calculation of the quantity of fuel corresponding to the second type of fuel, consumed after starting of the internal combustion engine, obtained by the second calculation block 105 can then be done for example also by integration of the injection duration. ti for a given engine speed (rotational speed) nmot, in a manner known to those skilled in the art. In this calculation it is also possible to take into account one or more other input variables (parameters) Io such as, for example, the temperature of the fuel corresponding to the fuel of the second type of fuel, in a manner known in the art. skilled person. The quantity of fuel corresponding to the second type of fuel, consumed after the start of the internal combustion engine, is also supplied to the comparison element 110. The comparison element 110 checks whether the quantity of fuel consumed corresponding to the second type of fuel fuel, after the start of the internal combustion engine, is greater than the amount of fuel corresponding to the second type of fuel that has been introduced. If this is the case, we go to block 115; in the opposite case, block 120 is passed. From block 115, control 70 with the motor control ensures the adjustment of the operating parameters and the control variables necessary for the first operating mode which in this example correspond to the normal operating mode of the internal combustion engine 1 using fuel corresponding to the first type of fuel.

  In block 120, the control 70 and the motor control provide adjustment of the operating parameters and the control variables necessary for the second operating mode; in the present embodiment this corresponds to the start of the internal combustion engine 1 using: fuel corresponding to the second type of fuel. At the instant at which the comparison element 110 detects the first time after the start of the internal combustion engine, the quantity of fuel corresponding to the second type of fuel, consumed, greater than the quantity of fuel of the second type of fuel introduced, then, taking into account the duration between two calculation steps, substantially at the instant after the start of the implementation (activation) of the second fuel pump 35, to which the amount of fuel corresponding to the second The type of fuel pumped into the fuel distribution manifold 5 has been used.

Claims (9)

  1) A method of controlling an internal combustion engine (1) comprising a thermal engine operating with fuel, wherein different fuels are used for combustion in different modes of operation, characterized in that the fuel corresponding to a first type of fuel for a first mode of operation in a fuel distribution ramp (5), this ramp being equipped with at least one fuel injector (10, 15, 20, 25) for supplying fuel to the engine with internal combustion, and the fuel corresponding to the second fuel type is pumped for a second operating mode in the fuel distribution manifold (5).   2) A method according to claim 1, characterized in that as a first operating mode is chosen the normal operating mode of the internal combustion engine and as a second operating mode is chosen a starting mode of the internal combustion engine, particularly if It is below a predefined engine temperature.   3) Process according to claim 1, characterized in that the fuel corresponding to the first type of fuel is pumped by a first fuel pump (30) in the fuel distribution manifold (5).   4) Method according to claim 3, characterized in that during the time during which fuel is pumped corresponding to the second type of fuel in the fuel distribution manifold (5), a non-return valve (40) equipping a pipe connection (50) between the first fuel pump (30) and the fuel distribution manifold (5) is short-circuited via a bypass valve (55).   5) Method according to claim 1, characterized in that one determines the amount of fuel corresponding to the second type of fuel and pumped into the fuel distribution manifold in the second mode of operation according to the operating parameters of the combustion engine internal (1), according to the operating parameters of the internal combustion engine (1) an instant is determined at which the fuel corresponding to the second type of fuel, pumped into the fuel distribution manifold for the second operating mode, has been consumed the operating parameters of the internal combustion engine are adjusted up to this time for the operation of the engine with the second type of fuel, and then the operating parameters of the combustion engine (1) are set for operation. of the engine with the first type of fuel.   Process according to Claim 5, characterized in that the quantity of fuel corresponding to the second type of fuel which has been pumped in the second mode of operation in the fuel distribution manifold (5) is determined as a function of the supply voltage and the control time of the second fuel pump (35).   7) A method according to claim 5 or 6, characterized in that it is determined at which time the fuel corresponding to the second type of fuel pumped in the fuel distribution manifold (5) for the second mode of operation has been consumed, depending on the speed of rotation of the engine (engine speed) and the control time of at least one injector (10, 15, 20, 25).   8) Process according to claim 1, characterized in that the fuel corresponding to the second type of fuel is pumped into the fuel distribution manifold (5) via a second fuel pump (35).   9) Control device of an internal combustion engine (1) comprising a heat engine supplied with different fuels provided for combustion according to the various operating modes, characterized in that a first fuel pump (30) pumps the fuel corresponding to a first type of fuel for a first mode of operation, in a fuel distribution ramp (5) equipped with at least one fuel injector (10, 15, 20, 25) which supplies the fuel to the engine, and a second fuel pump (35) pumps fuel to a second type of fuel for a second mode of operation in the fuel distribution manifold (5).