EP1068435B1 - Fuel supply system for an internal combustion engine, especially of a motor vehicle - Google Patents

Description

State of the art

The invention relates to a method for operating a Fuel supply system for an internal combustion engine in particular a motor vehicle in which fuel from a pump is pumped into a pressure accumulator, and in which the pressure in the pressure accumulator by means of a Pressure control valve is controllable and / or adjustable. Furthermore The invention relates to a corresponding program corresponding storage medium and a corresponding one Control device for an internal combustion engine.

Such a method is known from DE 195 39 885 A1.
According to DE-A-3 304 605, a fuel pressure accumulator is charged by the connection.

To an internal combustion engine, for example of a motor vehicle are becoming increasingly demanding with regard to a Reduction of fuel consumption and the exhaust gases generated with a desired increase in performance. For this purpose, modern internal combustion engines are one Provided fuel supply system in which the feed of fuel in the combustion chamber of the internal combustion engine electronically, especially with a computerized one Control unit, controlled and / or regulated. It is possible to put the fuel in an air intake pipe Internal combustion engine or directly into the combustion chamber Inject internal combustion engine.

Especially with the latter type, the so-called Direct injection, it is required that the fuel is injected into the combustion chamber under pressure. To this Purpose is a pressure accumulator in which the fuel pumped by means of a pump and under high pressure is set. From there the fuel is then over Injectors in the combustion chambers of the internal combustion engine injected.

When starting the internal combustion engine, the aforementioned is high Pressure mostly not or at least not immediately available. The The engine must therefore be started separately controlled and / or regulated. They are already there mentioned boundary conditions such. B. low pollutant emissions to fulfill.

The object of the invention is to provide a method for operating of a fuel supply system for an internal combustion engine to create with the best possible start of the Internal combustion engine is feasible.

This task is carried out in a procedure or a Fuel supply system of the type mentioned at the beginning solved according to the invention, with the characteristics according to Claim 1.

Closing the pressure control valve turns on Defined state of the internal combustion engine for the impending startup process. It will also achieved that the pressure in the pressure accumulator no longer continues to fall.

The pressure control valve turns on by turning on the ignition closed, and is switched on by this ignition also the pump for feeding fuel into the pressure accumulator switched on, this means that the pressure in the The pressure accumulator depends on the delivery rate of the pump and possibly increases accordingly. This is for that intended starting of the internal combustion engine in particular advantageous.

By controlling and / or regulating in normal operation The specified speed limit is exceeded simple way of transitioning control and / or regulation the internal combustion engine from the starting process in the Normal operation reached.

In an advantageous embodiment of the invention Pressure control valve at least partially opened when the Internal combustion engine is started and the first There are rotational movements. So it is possible to print in the pressure accumulator with the help of the pressure control valve control and / or regulate.

In an advantageous development of the invention Pressure control valve depending on the temperature of the Internal combustion engine opened. So that the pressure in the Pressure accumulator to the temperature of the internal combustion engine be adjusted.

In another advantageous development of the invention the pressure control valve depending on the number of injections already carried out in the internal combustion engine open. The internal combustion engine can thus be operated in a simple manner be adapted to the course of the starting process.

The realization of the method according to the invention in the form of a control element, that for a control unit of an internal combustion engine, in particular of a motor vehicle is provided. It is on the Control stored a program on a Computing device, in particular on a microprocessor, executable and for executing the invention Process is suitable. In particular, as a control element an electrical storage medium is used, for example a read-only memory.

Figur 1

zeigt eine schematische Darstellung eines Ausführungsbeispiels eines erfindungsgemäßen Kraftstoffversorgungssystems,

Figur 2

zeigt ein schematisches Blockschaltbild eines Ausführungsbeispiels eines erfindungsgemäßen Verfahrens zum Betreiben des Kraftstoffversorgungssystems der Figur 1, und

Figur 3

zeigt ein schematisches Zeitdiagramm zu dem Verfahren nach der Figur 2.

Further features, possible applications and advantages of the invention result from the following description of exemplary embodiments of the invention, which are shown in the figures of the drawing.

Figure 1

shows a schematic representation of an embodiment of a fuel supply system according to the invention,

Figure 2

shows a schematic block diagram of an embodiment of a method according to the invention for operating the fuel supply system of Figure 1, and

Figure 3

shows a schematic time diagram for the method according to FIG. 2.

1 shows a fuel supply system 1 shown for use in an internal combustion engine a motor vehicle is provided. In which Fuel supply system 1 is a so-called common rail system, which is particularly in one Internal combustion engine with gasoline direct injection Application comes.

The fuel supply system 1 has a pressure accumulator 2 on, with a pressure sensor 3 and a Pressure control valve (DSV) 4 is provided. The accumulator 2 is via a pressure line 5 with a high pressure pump 6 connected. The high pressure pump 6 is with the Internal combustion engine coupled and generates a high pressure with the internal combustion engine rotating. The high pressure pump 6 is to the pressure control valve 4 via a pressure line 8 connected. Via a pressure line 9 and a filter is the pressure control valve 4 and thus the High-pressure pump 6 with an electric fuel pump 10 connected, which is suitable for fuel from a Suction fuel tank 11. The electrical Fuel pump 10 generates pressure as soon as one There is tension on it. This is at least for a short time Case when the ignition of the motor vehicle is turned on is.

The fuel supply system 1 has four Injectors 13 on the pressure lines 14 with the Pressure accumulator 2 are connected. The injectors 13 are suitable for fuel in appropriate combustion chambers to inject the internal combustion engine.

The pressure sensor 3 is connected by means of a signal line 15 connected to a control unit 16 to which a further A plurality of signal lines other than input lines are connected. By means of a signal line 17 Fuel pump 10 and via a signal line 18 is that Pressure control valve 4 connected to the control unit 16. Of the injection valves 13 are also means Signal lines 19 connected to the control unit 16.

In normal operation of the internal combustion engine, the fuel from the fuel pump 10 to the fuel tank 11 the high pressure pump 6 is pumped. With the help of the high pressure pump 6, a pressure is generated in the pressure accumulator 2 the pressure sensor 3 is measured and by a corresponding actuation of the pressure control valve 4 and / or Control of the fuel pump 10 to a desired value can be controlled and / or regulated. About the Injector 13 is then the fuel in the Combustion chambers of the internal combustion engine injected.

For the dimensioning of the respective combustion chamber The quantity of fuel to be injected is, among others Pressure in the pressure accumulator 2 is essential. The bigger the Pressure in the accumulator 2, the more fuel is in the combustion chamber during the same injection time injected. This pressure in the pressure accumulator 2 can be from can be controlled and / or regulated by the control unit 16.

For this purpose, control unit 16 controls, for example Pressure control valve 4 in its closed state, so that the high pressure pump 6 and fuel pump 10 always one Generate further increasing pressure in the pressure accumulator 2. This = increasing pressure can be from the pressure sensor 3 be measured.

It is also possible that the control device 16 Speed of the fuel pump 10 increases, resulting in a increased delivery capacity of the fuel pump 10 leads and has an increased pressure in the pressure accumulator 2. The increase in this pressure and thus the increase in Speed or the delivery rate of the fuel pump 10 can also be determined via the pressure sensor 3.

To start the internal combustion engine, a plurality of special boundary conditions are taken into account. this will by the following, illustrated with reference to Figures 2 and 3 Method carried out by the control unit 16. You can the individual blocks of the process e.g. as modules of one Program or the like implemented in the control unit 16 his.

Before a point in time t1 shown in FIG Ignition of the internal combustion engine not yet switched on the starter of the internal combustion engine has not yet been actuated. The two binary signals Bst shown in FIG and Bstend have a condition at least for the this description is not relevant.

After the time t1, the binary signals have Bst and Bstend following properties. The binary signal Bst is only then "1" when the ignition is switched on, the starter Internal combustion engine in a rotary motion, the Internal combustion engine but a predetermined speed limit NG has not yet exceeded. The binary signal is Bstend then "1" when the starting of the internal combustion engine ends is, the internal combustion engine the predetermined speed limit NG has exceeded.

At time t1, the ignition of the internal combustion engine switched on, but the starter does not yet run Rotary motion. This is equivalent to the fact that a Motor vehicle users start the internal combustion engine wants, but the internal combustion engine does not yet have a rotary movement performs. The binary signals Bst and Bstend are in time t1 to "0". From time t1 to time t2 remains the ignition is switched on and the starter is not yet actuated. The binary signals Bst and Bstend remain on "0".

In the period between the times t1 and t2 that will Pressure control valve 4 closed. According to the Figure 2 is a predetermined, preferably constant Clock ratio K via two switches 20, 21 to the Pressure control valve 4 passed. With the clock ratio K the pressure control valve 4 is closed in its Condition transferred if the pressure control valve 4 is not is closed, or it will be the closed state of the Pressure control valve 4 maintained.

For this purpose, the two binary signals Bst and Based on two inverters 22, 23 inverted and an AND gate 24 fed. The AND gate 24 becomes a binary one "1" generates the switch 20 in that state transferred, which is not shown in Figure 2.

Furthermore, the inverted binary signal Bstend, ie a binary "1", the switch 21, which this in transferred the state that is not in Figure 2 is shown.

Overall, this has the effect - as already mentioned - that Clock ratio K via the switches 20, 21 to the Pressure control valve 7 is passed.

At time t2 in FIG. 3, the starter moves the Internal combustion engine in a rotary motion. So that will be Binary signal Bst to "1". The speed N is also the Internal combustion engine not equal to zero and increases. As soon as the Internal combustion engine due to the injections carried out of fuel into their own combustion chambers Force executes a rotary movement, the speed N der increases Internal combustion engine continues. The internal combustion engine is started.

As soon as the speed N of the internal combustion engine Speed limit NG, for example 800 revolutions per Minute, exceeds the binary signal Bst again "0" and the binary signal Bstend becomes "1". This is done in 3 at time t3.

In the period between times t2 and t3, this becomes Pressure control valve 4 at least partially opened. this will achieved in that a variable clock ratio V read from a map 25 and via the switches 20, 21 is passed on to the pressure control valve 4. by virtue of of the changed binary signal Bst, the switch 20 falls the state shown in FIG. 3. There the binary signal Bstend in the period between the At times t2 and t3 is still "0", the switch remains 21 in the state not shown in FIG. 3. In order to the duty cycle V comes from the map 25 via the Switches 20, 21 to the pressure control valve 4.

The map 25 is dependent on the temperature TM Internal combustion engine and the number of ATI injections, which at the present start of the Internal combustion engine have already been run. It is possible that the map 25 alternatively and / or additionally also from other operating variables of the internal combustion engine is dependent. The clock ratio generated by the map V mostly controls the pressure control valve 4 open, at least not in a closed state. Intermediate states are also possible.

The internal combustion engine already reaches the point in time t3 mentioned speed limit NG. As a result, the Starting the engine is complete and that Binary signal Bstend becomes "1". The inverted binary signal Bursting, ie a binary "0", causes switch 21 remains in the state shown in FIG. 3. So neither the duty cycle K, nor that Duty cycle V passed on to the pressure control valve 4.

Instead, a duty cycle N is applied to the Pressure control valve 4 passed in one Normal operation of the internal combustion engine is generated. This Normal operation has already been explained and is in the figure 2 by means of a block 26.

Overall, this results in the following starting process Engine:

Before time t1, i.e. before switching on the ignition and before starting the starter, it can Pressure control valve 4 opened in any state or be closed.

At time t1, that is as soon as the ignition of the motor vehicle is switched on, the pressure control valve 4 closed. This state will continue until time t2 maintained, i.e. until the starter is actuated. So that is the pressure in the pressure accumulator 2 during this period depending on the pressure existing before time t1 and that of the electric fuel pump 10 generated pressure.

At time t2, i.e. with the ignition switched on and itself rotating starter, the pressure control valve 4 at least partially open. This condition is up to date Maintain t3, that is, until the start of the Internal combustion engine ended and the speed limit NG is reached. Due to the generated by the starter low speed comes with the internal combustion engine coupled high-pressure pump 6 not yet effective. The Pressure in the pressure accumulator 2 is therefore during this period largely dependent on the electric fuel pump 10th

From time t3, the high pressure pump 6 comes in essentially fully effective. So that's the pressure in that Pressure accumulator largely from the time t3 High pressure pump 6 dependent.

Claims (7)

1. Method for operating a fuel supply system (1) for an internal combustion engine, in particular of a motor vehicle, in which fuel is pumped by a pump (6, 10) into a pressure accumulator (2), and in which the pressure in the pressure accumulator (2) can be controlled and/or regulated by means of a pressure control valve (4), the pressure control valve (4) being closed if the internal combustion engine is to be started but there is not yet any rotational movement, characterized in that the pressure control valve (4) is controlled and/or regulated in accordance with normal operation when a predetermined rotational-speed limit (NG) is exceeded.
2. Method according to Claim 1, characterized in that the pressure control valve (4) is at least partially opened when the internal combustion engine is started and executes the first rotational movements.
3. Method according to Claim 2, characterized in that the pressure control valve (4) is opened as a function of the temperature (TM) of the internal combustion engine.
4. Method according to Claim 2 or 3, characterized in that the pressure control valve (4) is opened as a function of the number (ATI) of injections into the internal combustion engine that have already been carried out.
5. Programme, characterized in that it is programmed for use in a method according to one of Claims 1 to 4.
6. Electric storage medium for a control unit (16) of an internal combustion engine, characterized in that a programme is stored on it for use in a method according to one of Claims 1 to 4.
7. Control unit (16) for an internal combustion engine, characterized in that it is set up for use in a method according to one of Claims 1 to 4.

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