FR2708048A1 - Method of controlling an internal combustion engine. - Google Patents

Abstract

Method for controlling an internal combustion engine (1) intended in particular to equip a motor vehicle, said engine (1) comprising an electronic control system (7) of the type comprising a central unit (70), random access memories (71 ) and dead (72, 73), analogue-digital converters and various input and output interfaces (74), characterized in that it consists on the one hand, in recognizing the presence or absence of at least one predetermined member (2) influencing the operation of said engine (1) and optionally driven by said engine (1) and on the other hand to be chosen from among a plurality of predefined strategies for controlling the fuel injection and / or the ignition of the spark plugs of said engine (1) corresponding to the presence or absence of said optional member (2), the appropriate strategy for controlling said engine (1).

Description

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METHOD FOR CONTROLLING A MOTOR WITH

INTERNAL COMBUSTION

  The present invention relates to a control method designed for injecting fuel and / or igniting an internal combustion engine fitted in particular to a motor vehicle. The present invention relates more particularly to a method for selecting strategies for controlling a combustion engine, as a function of the nature of the energy consuming members driven by

this last.

  It is known to control the operation of an internal combustion engine for a motor vehicle thanks to an electronic control system which calculates and controls the flow rate of the fuel injectors and / or the ignition of the spark plugs from the values taken by a certain number of parameters related to engine operation. Among the information necessary for controlling an engine, there is that relating to the presence and implementation of the various members on board the vehicle and driven by the engine. These organs which act on the -2functioning of the engine are in particular: the gear change mechanism, the air conditioning system or even the assisted device

wheel traction control.

  However, a certain number of these on-board members are optional systems and are therefore not systematically driven by the engine, which therefore makes it necessary to provide separate versions for electronic engine control systems which are adapted to the equipment.

of the vehicle.

  The object of the present invention is therefore to reduce the costly diversity of electronic engine control systems which can be fitted to motor vehicles by proposing a single electronic control system capable of appropriately controlling the operation of the engine, whatever the driven organs. by the engine. The control method according to the invention relates to an internal combustion engine intended in particular to equip a motor vehicle. This engine comprises an electronic control system comprising a central unit, a random access memory, read-only memories, analog-digital converters, and various interfaces

inputs and outputs.

  According to the invention, the method of controlling an internal combustion engine is characterized in that it consists on the one hand, in recognizing the presence or the absence of at least one predetermined member -3- influencing the operation of the engine and optionally mounted on the vehicle and on the other hand, to be chosen from a plurality of predefined strategies for controlling fuel injection and / or lighting the engine spark plugs corresponding to the presence or absence of the vehicle of this optional body, the appropriate strategy

to control the motor.

  According to another characteristic of the control method according to the invention, the recognition of the presence or absence of this optional member is effected by the analysis of the signals received at the input of the engine control system reserved for communication messages between said organ and the

engine control system.

  According to another characteristic of the control method according to the invention, the recognition of the presence or absence of this optional member is effected under predetermined conditions of

engine operation.

  According to another characteristic of the control method according to the invention, as long as the recognition of the presence or absence of the optional member has not been made, the engine control strategy adopted is chosen arbitrarily. According to another characteristic of the control method according to the invention, the recognition of the presence or absence of the optional member

  is operated each time the engine is started.

  According to another characteristic of the control method according to the invention, each recognition of the presence or absence of the optional member is systematically compared with the previous recognitions, so as to

  detect any malfunctions.

  According to another characteristic of the control method according to the invention, the optional member is constituted by a mechanism for changing the

automatic gears.

  The objects, aspects and advantages of the present invention will be better understood from the

  description presented below of a mode of

  embodiment of the invention, given by way of nonlimiting example, with reference to the accompanying drawing, in which: - Figure 1 is a partial view of an internal combustion engine equipped for the implementation of the method according to the 'invention; - Figure 2 is a block diagram specifying the different steps of the method according to the invention. Figure 1 schematically shows a drive system of a motor vehicle comprising an internal combustion engine associated with a transmission system comprising a gear change mechanism. This mechanism can be depending on the option chosen, a manual gearbox or a gearbox

automatic.

  _5- The control method according to the invention, which is implemented directly by the electronic control system fitted to the engine, therefore relates more particularly in this present example, the recognition of the type of gear change mechanism and the selection of control strategies for the corresponding injection and / or ignition. The method which is the subject of the invention is not however limited to this single example and can be used by analogy for the recognition of other optional energy consuming members fitted to the motor, such as

than an air conditioning system.

  The effect of the nature of the gearbox on the engine control is indeed important for the engine control, both for taking into account the transmission ratio which is different depending on the nature of the gearbox fitted to the vehicle , that for certain applications specific to the use of an automatic gearbox such as in particular the reduction or blurring of the engine torque when changing the gear ratios, in particular confers the document US-A-5,001,642. The engine control strategies are therefore very different depending on the nature of the gearbox. The invention therefore consists in integrating into the read-only memory of the electronic system the control strategies corresponding to each of the types of gear change mechanism and by an additional part of strategy to ensure the recognition of the gear change mechanism and to select the strategies for

appropriate command.

  The multi-cylinder internal combustion engine referenced 1 is, in a manner known per se, equipped with a fuel supply device of the electronically controlled multipoint injection type where each cylinder is supplied with

  fuel by a specific electro-injector 5.

  The opening of each electro-injector 5 is controlled by an electronic control system 7. The electronic engine control system 7 conventionally comprises a computer of the type comprising a central unit CPU (70), a random access memory RAM (71), ROM read-only memories (72) and

  EEPROM (73), analog converters-

  digital and various input and output interfaces (74). It receives input signals relating to the operation of the engine and in particular those emitted by a crankshaft sensor 4 which allow the tracking of the passage to the top dead center of each of the cylinders, and the determination of the engine rotation speed, as well as at

  functioning of the various inter-

  acting with the engine. It performs operations and generates output signals to destination

in particular injectors 5.

  In the electronic control system 7 are therefore stored two series of fundamental strategies and parameters for the optimal adjustment of the engine corresponding respectively to the use of a manual gearbox and to the use of a gearbox. automatic gears. These parameters are obtained before the engine test bench. These are, for example, the parameters relating to the fuel injection phase in each of the engine cylinders, the fuel injection duration which corresponds to an amount of fuel injected, or even the phase

  for igniting candles not shown.

  In accordance with the figures and more particularly in FIG. 2, the method according to

the invention is as follows.

  The electronic engine control system according to the invention therefore has all the strategies and parameters corresponding to each of the types of gear change mechanism that can be driven by the engine. It suffices to recognize the mechanism actually driven and to select the control strategies concerned from the various strategies in memory. The electronic engine control system according to the invention is then able to appropriately control the operation of the engine, regardless of the type of gear change mechanism.

associated with the latter.

  The recognition of the type of gear change mechanism fitted to the engine is based on the recognition of the presence or absence of the automatic gearbox, its absence signifying the use of a manual gearbox. Recognition of the presence or absence of the automatic gearbox is based on the fact that the electronic system systematically includes a specific input 8 reserved for the connection of the electronic engine control system with the electronic control system 6 of the gearbox automatic gearbox 2, when it is such a gearbox which has been mounted on the vehicle. This input 8 is used to receive the various communication messages produced by the electronic control system 6 of the gearbox 2 necessary for controlling the injection and / or ignition of the engine 1. It therefore suffices to analyze the communication signals received on this input 8 to deduce therefrom that an automatic gearbox is well or not fitted to the engine, and therefore to choose the appropriate control strategies. To operate this detection, the level of the signal received at input 8 is therefore read, for example after each engine start. This reading is triggered under predetermined conditions, which depend on the communication protocol adopted between the electronic control system 6 of the automatic gearbox 2 and the engine control system 7, and on the operation of the engine. Its triggering can for example be determined, by the crossing by the speed N supplied by the crankshaft sensor 4 of a speed threshold Nseuil of the engine or, by a given engine operating time. This trigger criterion is determined so that at this instant, the electronic control system 6 of the automatic gearbox 2,

  transmits to the engine control system.

  The detection of the reception of a signal on the input 8 is effected for example from a communication interface associated with the input 8. This communication interface operating at a predetermined frequency is used to decode the data contained in the communication messages, in the form of bytes directly interpretable by the central processing unit CPU. To do this, it has a flag making it possible to signal the reception of a datum to the central unit and an associated memory box for storing the corresponding byte. It is therefore sufficient to check the operation of this communication interface to verify whether a message has been sent or not. A more or less elaborate recognition strategy can be adopted to take into account the occurrence of any parasitic phenomena that can be interpreted as receiving data. This detection having been made, two possibilities are then to be considered: either no signal has been identified and then it is deduced therefrom that the output 8 is not connected to an electronic system for controlling a gearbox and therefore that '' a manual gearbox was fitted to the vehicle; either a communication signal from an electronic control system of a gearbox has been identified and we deduce that the

  engine drives an automatic gearbox.

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  It is therefore possible to assign a code "01" or "11", corresponding respectively to a manual gearbox or an automatic gearbox, to a register FLAGBV status indicator used in a program loop for selecting control strategies to use for the

engine control.

  The value of the FLAGBV register therefore determines the choice of motor control strategies. In the hypothesis o, between the moment of launching the engine and that of the acquisition of FLAGBV, we need to choose a control strategy, we can then choose the latter arbitrarily, for example the value of FLAGBV recorded during the previous operating cycle and stored in a non-volatile BVSTB memory box. In the event of a discrepancy between this arbitrary value and the value of FLAGBV, the change in the engine control strategies may take place either during predetermined engine operating ranges or at any point of operation. This BVSTB memory box is also, for example, initialized at the origin and also in the event of erasure, at "01" corresponding to the use of a

manual gears.

  Such a method also makes it possible to diagnose a possible failure of the system, such as a break in the connection between the control system 6 and the engine control system 7 or even the erasure of certain memories. To do this, simply compare the value of FLAGBV with that recorded

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  during the previous start-up and stored in the BVSTB memory box. If there is a difference between these values, a SUB_DIAGNOSTIC strategy for operating in degraded mode and / or sending a warning signal to the driver can therefore be triggered. Furthermore, it is possible to further increase the security of the process, in particular to guard against the risks of erasing certain memories already mentioned, by using an additional memory box BVE2P located in the erasable read-only memory EEPROM of the electronic system 7 The memory box BVE2P which is initially blank (BVE2P = "00"), is configured by the value of FLAGBV as soon as the same type of gearbox has been recognized twice consecutively and this is the content of this box BVE2P memory which will then be taken into account by the strategy selection program loop

used to control the motor.

  As long as the BVE2P memory box is not configured, the value of FLAGBV or, failing this, the value of BVSTB is taken into account. Once configured, in the event of accidental erasure of BVE2P, it is then reinitialized with the value of BVSTB (similarly, it resets BVSTB with the value of BVE2P). As previously, a system diagnosis can be made by comparing the values of BVE2P and BVSTB with that of FLAGBV. If there is a difference between these values, it is therefore possible to trigger different SUB DIAGNOSTIC strategies for operating in degraded mode and / or sending a warning signal

to the driver.

  Thus, thanks to the method according to the invention, it is possible to reduce the diversity of electronic systems capable of equipping the same motor, by directly integrating into a single system all of the different settings and different control strategies corresponding to the different configurations. possible use of the engine and by choosing the appropriate parameters and strategies based on the recognition of the driven organs

actually by the engine.

  Of course, the invention is in no way limited to the embodiment described and illustrated

  which was only given as an example.

  On the contrary, the invention includes all the technical equivalents of the means described as well as their combinations if these are carried out

following his spirit.

  Thus, the reading of the level of the signal received on input 8 can be carried out at a predetermined rate, for example all n starts, with n integer greater than or equal to 2, and no longer systematically after each start of the

engine.

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Claims (1)

  [1] Method for controlling an internal combustion engine (1) intended in particular for equipping a motor vehicle, said engine (1) comprising an electronic control system (7) of the type comprising a central unit (70), memories live (71) and dead (72,73), analog-digital converters and various input and output interfaces. (74), characterized in that it consists, on the one hand, in recognizing the presence or absence of at least one predetermined member (2) influencing the operation of said motor (1) and optionally driven by said motor ( 1) and on the other hand to choose, from a plurality of predefined strategies for controlling the injection of fuel and / or the ignition of the spark plugs of said engine (1) corresponding to the presence or absence of said optional member (2), the appropriate strategy for controlling said motor (1). [2] Method for controlling an internal combustion engine (1) according to claim 1, characterized in that the recognition of the presence or absence of said optional member (2) is effected by analysis of the signals received at the input (8) of said engine control system (7) - 14 reserved for communication messages between said   member (2) and said engine control system (7).   [3] Method for controlling an internal combustion engine (1) according to any one of   claims 1 to 2, characterized in that the   recognition of the presence or absence of said optional member (2) is operated under predetermined conditions (Nseuil) of operation of the engine.   [4] Method for controlling an internal combustion engine (1) according to claim 3, characterized in that as long as the recognition of the presence or absence of said optional member (2) has not been made, the ordering strategy of the   engine selected is chosen arbitrarily.   [5] Method for controlling an internal combustion engine (1) according to any one of   claims 1 to 4, characterized in that the   recognition of the presence or absence of said optional member (2) is operated at each start motor (1).   [6] Method for controlling an internal combustion engine (1) according to any one of   claims 1 to 4, characterized in that each   recognition of the presence or absence of said optional body (2) is systematically compared with the previous recognitions, so as to   detect any malfunctions.   [7] Method for controlling an internal combustion engine (1) according to any one of - 15-   claims 1 to 5, characterized in that said   optional body is constituted by a mechanism   automatic gear change (2).