EP0635630A1 - Method for controlling an internal combustion engine - Google Patents

Abstract

Method for controlling an internal combustion engine (1) intended particularly to equip a motor vehicle, the said engine (1) including an electronic control system (7) of the type comprising a central unit (70), a read-write memory (71) and read-only memories (72,73), analogue-digital converters and various input and output interfaces (74), characterised in that it consists, on the one hand, in recognising the presence or absence of at least one predetermined member (2) influencing the operation of the said engine (1) and entrained as an option by the said engine (1) and, on the other hand, in choosing the appropriate strategy for controlling the said engine (1) from among a plurality of predefined strategies for controlling the injection of fuel and/or firing of the spark plugs of the said engine (1), these strategies corresponding to the presence or absence of the said optional member (2). <IMAGE>

Description

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 the latter.

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 that act on the engine operation include: the gear change mechanism, the air conditioning system or even the wheel traction assisted device.

However, a certain number of these on-board members are optional systems and are therefore not systematically driven by the engine, which therefore requires 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 input and output interfaces.

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 absence of at least one member predetermined influencing the operation of the engine and fitted as an option on the vehicle and on the other hand, to be chosen from a plurality of predefined strategies for controlling fuel injection and / or igniting the engine spark plugs corresponding to the presence or not on the vehicle of this optional unit, the appropriate strategy for controlling the engine.

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 member 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 operated 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 at each start of the engine.

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 possible malfunctions.

According to another characteristic of the control method according to the invention, the optional member is constituted by an automatic gear change mechanism.

• la figure 1 est une vue partielle d'un moteur à combustion interne équipé pour la mise en oeuvre du procédé selon l'invention ;
• la figure 2 est un schéma fonctionnel précisant les différentes étapes du procédé selon l'invention.

The aims, aspects and advantages of the present invention will be better understood from the description presented below of an embodiment of the invention, given by way of nonlimiting example, with reference to the appended 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;
• FIG. 2 is a functional 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 an automatic gearbox.

The control method according to the invention, which is implemented directly by the electronic control system equipping the motor, therefore relates more particularly in this present example, to the recognition of the type of gear change mechanism and the selection of the strategies for piloting of 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 engine, such as an air conditioning device.

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 ROM 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 selection of the appropriate control strategies.

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 multi-point 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 processing unit CPU (70), a random access memory RAM (71), ROM (ROM) and EEPROM memories (73), analog-digital converters 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 the operation of the various organs interacting with the engine. It performs operations and generates output signals intended in particular for injectors 5.

In the electronic control system 7 are therefore stored two series of strategies and fundamental parameters for the optimal adjustment of the motor corresponding respectively to the use of a manual gearbox and the use of an automatic gearbox. 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 ignition phase of the spark plugs not shown.

According to the figures and more particularly to Figure 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 transmission 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 automatic gearbox 2, when such a box has been fitted 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 transmission 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 operated 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 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 control system of a gearbox and therefore that a manual gearbox has been mounted on the vehicle;
or a communication signal from an electronic control system for a gearbox has been identified and it can be deduced therefrom that the engine drives an automatic gearbox.

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 motor control.

The value of the FLAGBV register therefore determines the choice of motor control strategies. In the hypothesis that, between the moment of launching the engine and that of acquiring 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 gearbox.

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 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 protect 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 memory box BVE2P which will then be taken into account by the program selection loop for the strategies 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, we then reinitialize the latter with the value of BVSTB (similarly, we reinitialize 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, we can therefore trigger different SUB_DIAGNOSTIC strategies for operating in mode degraded 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 organs actually driven by the engine.

Of course, the invention is in no way limited to the embodiment described and illustrated, which has been given only by way of example.

On the contrary, the invention includes all the technical equivalents of the means described and their combinations if these are carried out according to the spirit.

Thus, the reading of the level of the signal received on the 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 engine start.

Claims (6)

[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 the absence at least one predetermined member (2) influencing the operation of said motor (1) and optionally driven by said motor (1) by analyzing the signals received at a reserved input (8) of said motor control system (7) upon receipt of the communication messages automatically transmitted by said member (2) according to a predetermined protocol and on the other hand to be chosen, from a plurality of predefined strategies for controlling the injection of fuel and / or the ignition of spark plugs of said motor (1) horn responding 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 operated under predetermined conditions (Nseuil) of engine operation. [3] Method for controlling an internal combustion engine (1) according to claim 2, characterized in that as long as the recognition of the presence or absence of said optional member (2) has not been carried out, the engine control strategy adopted is chosen arbitrarily. [4] A method of controlling an internal combustion engine (1) according to any one of claims 1 to 3, characterized in that the recognition of the presence or absence of said optional member (2) is operated at each engine start (1). [5] Method for controlling an internal combustion engine (1) according to any one of claims 1 to 3, characterized in that each recognition of the presence or absence of said optional member (2) is systematically compared to the previous recognitions, so as to detect possible malfunctions. [6] A method of controlling an internal combustion engine (1) according to any one of claims 1 to 5, characterized in that said optional member is constituted by an automatic gear change mechanism (2). Claims 1 to 5, characterized in that said optional member is constituted by an automatic gear change mechanism (2).

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