EP0651152B1 - Control process for an internal combustion engine fuel pump - Google Patents

Description

The present invention relates to a method control for driving the pump fuel from an internal combustion engine fitted including a motor vehicle. The current the invention relates more particularly to a method control intended to favor the setting under engine fuel system pressure before startup of the latter. Such a process is known from US-A-5,175,663.

The supply circuit of a internal combustion conventionally includes a fuel supply system under pressure from a storage tank to the electro-injectors controlled by an electronic system of engine control which determines the amount of fuel to be injected according to the conditions of engine operation. Traditionally injectors are supplied with fuel under a constant pressure, the amount of fuel injected then being determined by the duration opening times or injection times.

The fuel system is therefore equipped an electric pump that delivers fuel to a given pressure whatever the regime of engine operation. The implementation of this pump is directly controlled by the electronic engine control system which determines the operating range of the so as to avoid any risk of accidental leakage of the fuel. The pump is only activated after starter drive and it is stopped as soon as the engine stops.

To facilitate starting the engine, however authorizes the early activation of the fuel pump for a predetermined period, also called time delay, as soon as the contact has been put on i.e. as soon as the control system motor is energized. So the circuit of fuel is already under pressure when the starter is actuated, allowing injection immediately the required quantities of fuel.

This timeout is traditionally constant for a given motor and is relatively brief in the order of a few seconds, for security issues. Now it turns out that such timing is insufficient to ensure the setting fuel system pressure in certain circumstances and in particular when the fuel system is empty, which is the case at get out of the production lines.

It therefore follows in these circumstances particular, a relatively long actuation of the starter to allow time for pressure to fuel to rise and thus allow to operate injection of sufficient quantities of fuel. This more or less prolonged actuation of the starter can prove to be harmful for the duration life of the electric battery and starter vehicle which are then very strongly requested.

The object of the present invention is therefore to remove this drawback of the prior art by proposing a method of controlling the pump fuel from an internal combustion engine according to which the delay time is adapted in forecast of engine requirements.

The method according to the invention is more particularly intended to control a pump fuel fitted to the fuel system with a motor vehicle internal combustion engine, the fuel pump being of the drive type electric and being controlled by the engine control. this control process consists of activate the fuel pump early when powering up the system engine control electronics for a period predetermined time delay.

According to the invention, the control method of the fuel pump is characterized in that the length of the delay period is adjusted according to predetermined criteria.

According to another characteristic of the process of a fuel pump in accordance with invention, the delay period is adjusted according to operating criteria predetermined motor values.

According to another characteristic of the process of a fuel pump in accordance with the invention, the delay period is not adjusted only subject to a protocol authorization triggered by an operator.

According to another characteristic of the process of a fuel pump in accordance with invention, the delay period is adjusted according to fuel pressure prevailing in the fuel system.

According to another characteristic of the process of a fuel pump in accordance with invention, the delay period cannot take only two values, a first value normally used each time the power is turned on electronic engine control system, and a second value used only when predetermined circumstances, the first period time delay then being significantly longer shorter than the second delay period.

According to another characteristic of the process of a fuel pump in accordance with the invention, the second timeout period or long time delay is more particularly intended to be used when the fuel is empty.

According to another characteristic of the process of a fuel pump in accordance with the invention the long time delay is more especially intended to be used before the engine does not start for the first time.

According to another characteristic of the process of a fuel pump in accordance with the invention the long time delay is used after the engine control system has detected the sending by an operator of a predetermined signal and on condition that the engine is never previously worked.

According to another characteristic of the process of a fuel pump in accordance with the invention, the predetermined signal is defined by the foot-to-bottom position of the pedal accelerator.

According to another characteristic of the process of a fuel pump in accordance with the invention, the engine is considered to have operated when it reached a speed of predetermined rotation.

la figure 1 est une vue schématique du circuit de carburant d'un moteur à combustion interne ;

la figure 2 est un schéma électrique partiel de la commande de la pompe à carburant par le système de contrôle moteur ;

la figure 3 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 given below of an embodiment of the invention, given by way of nonlimiting example, with reference to the attached drawing, in which :

Figure 1 is a schematic view of the fuel circuit of an internal combustion engine;

FIG. 2 is a partial electrical diagram of the control of the fuel pump by the engine control system;

FIG. 3 is a functional diagram specifying the different steps of the method according to the invention.

Only the elements necessary for the understanding of the invention have been shown. To make the drawings easier to read, the same elements have the same references of a figure to the other.

The fuel injection system for a internal combustion engine shown in figure 1 conventionally comprises a circuit 10 for supplying the fuel under pressure from the fuel tank fuel 4 to the electro-injectors 9. The electro-injectors 9 are controlled by a system engine control electronics 3 which determines the opening times of the different injectors and therefore the amount of fuel injected.

The fuel supply system 10 includes a driven pump 5 electrically. Inside the pump 5, a safety valve prevents overpressure and outlet, a non-return valve prevents defusing from the circuit to the engine stop. Pump 5 sends fuel through a filter 6 and then into the injection rail 7 which communicates with the different injectors. Differential pressure injection, between the fuel supply circuit and the intake manifold is maintained constant, whatever the flow rate of the injectors 9, by the pressure regulator 8 which monitors the return flow to tank 4, fuel in excess.

The engine control system 3 includes conventionally a calculator comprising a unit central or CPU, a random access memory or RAM, a ROM or ROM, converters analog-digital and different interfaces inputs and outputs.

Engine control system 3 receives different input signals characteristic of the engine operation: load, speed, water temperature, manifold pressure, etc. performs operations and in turn generates output signals to organs directly controlled including injectors fuel 9 and fuel pump 5.

To activate the fuel pump the engine control system 3 therefore comprises, according to figure 2, an output 22 comprising a controlled switch such as a transistor 23, controlling the energization of a relay 24 connected to the + terminal of the battery vehicle through a connecting line 25 cooperating with a keyless contactor operated by the key to contact the vehicle (+ APC), to avoid any inadvertent starting of the fuel pump.

The triggering of relay 24 then operates the closure of line 28 directly connecting the battery (VBD) at fuel pump 3 and therefore the training of the latter.

Conventionally, the control system motor 3 controls the actuation of the fuel 5 in advance for a period called time delay, as soon as the ignition is on. The contact is determined either directly by recognizing the key transition "off" - "on" key or directly by placing motor control system voltage 3. The process of the fuel pump according to the invention therefore consists in adjusting this delay according to certain criteria predetermined.

Figure 3 shows schematically an algorithm to adapt the timing when the engine is started for the first time while the vehicle it equips leaves the chain of mounting.

To do this, the control system motor has two timeout values predetermined: a Tl value of around 30 s only intended for the first start-up so that allow the pressurization of the fuel initially empty and a Tc value approx. 1 s for subsequent starts.

The choice of timeout value long Tl by motor control system 3 is then determined by the combination of two criteria distinct: the absence of any functioning engine and recognition of a particular signal voluntarily caused by a operator and which is recognized by the engine control when it is switched on, by example the accelerator pedal in foot position background. This signal is identified either directly at from a potentiometer linked to the pedal acceleration, either indirectly from the full throttle position.

The combination of the two criteria allows to use the long delay Tl with the maximum security. The time delay Tl is not triggered only by special manipulation defining an authorization protocol, which eliminates the risks of unexpected triggering which could lead to a long dry rotation of the fuel pump. In addition, the user vehicle cannot re-create the conditions for starting the long delay.

To do this, the process consists first of all to come read the contents of a memory box FLAGDEM specific for computer 3 (memory not volatile EEPROM) which characterizes the fact that the engine has already run or not. This box memory initially at "0", is set to "1" as soon as the engine worked. To determine that the engine worked, we can take for example as a criterion, the fact that it has turned above a given rotation speed (1000rpm), we assign the code "1" to this box. The strategy recognition of engine operation and update of the content of the FLAGDEM register is classic and was not figured.

Reading the contents of the FLAGDEM register then determines the timeout value. If the content is "1", then we systematically use the short time delay Tc. The transistor 23 is therefore closed for a period equal to Tc.

If the content is "0", the system of engine control then waits for the authorization protocol, so it waits for a given period of time receiving a predetermined signal, for example positioning full foot of the accelerator pedal. We observe therefore the PA throttle position information supplied to the computer 3 by a specific sensor and which is also used for calculating the injection time, so as to identify the position full load, PAPF, corresponding to the position foot to the bottom of the accelerator pedal. Be the signal is located and then we use the long time delay Tl, either the signal is not identified and the time delay Tc is then used.

A certain number of safeties, no detailed on the flowchart of figure 3 support the implementation of the process. So the long time delay Tl is immediately stopped by switching off the ignition, which ensures system security in the event of a fuel system: fuel leak. By elsewhere, in the event of a memory fault or failure of the butterfly sensor, we use systematically the short time delay Tc.

The method according to the invention therefore makes it possible to simple way, by simple modification of the program control unit 3 and without any specific device is required, use a Tl delay adapted to the first start, this which reduces the time of the first bet en route and therefore avoid overheating of the starter and battery wear. Once the vehicle started, the timer resumes Tc value which ensures operation especially on the engine.

It is possible to provide the reset to "0" the FLAGDEM register during an after-sales intervention affecting the fuel system (change tank, etc.) to allow long delay T1.

Of course, the invention is by no means limited to the embodiment described and illustrated which was only given as an example.

So if we can consider adapting the timeout value to respond to this or that such special operating circumstance of the vehicle, we can also consider adapting the value of the time delay during each bet on the way, for example from information fuel pressure in the fuel system delivered by a pressure sensor placed on the injection rail 7, the time delay then being extended, subject to a maximum duration of security, until the pressure in the intake system reaches the pressure predetermined operation of electro-injectors 9.

Claims (10)

1. A process for controlling a fuel pump (5) equipping the fuel circuit (10) of a motor vehicle internal combustion engine (1), the fuel pump (5) being of the electric drive type and being pilot-controlled by the engine management system (3), comprising actuating the fuel pump (5) in anticipatory manner when voltage is applied to the electronic engine management system (3) for a predetermined time delay period (T), characterised in that the duration of the time delay period is adjusted in dependence on predetermined criteria (PAPF).
2. A process for controlling a fuel pump (5) according to claim 1 characterised in that said time delay period (T) is adjusted in accordance with predetermined operating criteria of the engine (1).
3. A process for controlling a fuel pump (5) according to claim 2 characterised in that said time delay period (T) is adjusted only subject to an enablement protocol (PAPF) triggered by an operator.
4. A process for controlling a fuel pump (5) according to claim 2 characterised in that said time delay period (T) is adjusted in dependence on the pressure of the fuel obtaining in the fuel circuit.
5. A process for controlling a fuel pump (5) according to any one of claims 1 to 3 characterised in that the time delay period (T) can assume two values, a first value (Tc) used normally each time voltage is applied to the electronic engine management system (3) and a second value (Tl) which is used only under predetermined circumstances, the first time delay period (Tc) being substantially shorter than the second time delay period (Tl).
6. A process for controlling a fuel pump (5) according to claim 5 characterised in that the second time delay period (Tl) is more particularly intended to be used when the fuel line (10) is empty.
7. A process for controlling a fuel pump (5) according to claim 6 characterised in that the second time delay period (Tl) is more particularly intended to be used before the engine (1) is started for the first time.
8. A process for controlling a fuel pump (5) according to claim 7 characterised in that said second time delay period (Tl) is used after the engine management system (3) has detected the despatch by an operator of a predetermined signal (PAPF) and provided that the engine (1) has never operated previously.
9. A process for controlling a fuel pump (5) according to claim 8 characterised in that said predetermined signal is defined by the foot hard-down position of the accelerator pedal.
10. A process for controlling a fuel pump (5) according to either one of claims 8 and 9 characterised in that the engine is considered as having operated when it has reached a predetermined speed of rotation.

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