DE19913477A1 - Operating fuel delivery device for internal combustion engine, especially for motor vehicle, involves influencing quantity control valve by battery voltage and/or depending on coil resistance - Google Patents

Abstract

The method involves regulating the quantity of fuel to the engine with a quantity control valve (15) and a high pressure pump (16) connected after it. The quantity control valve is influenced by a battery voltage to which the valve is subjected and/or depending on a coil resistance within the quantity control valve. An Independent claim is also included for a control element, esp. a ROM, for a controller and for a fuel delivery device.

Description

State of the art

The invention relates to a method for operating a Fuel supply device of an internal combustion engine in particular of a motor vehicle in which the Fuel quantity supplied to the internal combustion engine by means of a Volume control valve and a downstream high pressure pump is controlled and / or regulated. The invention relates also a control unit for one Fuel supply device for an internal combustion engine in particular a motor vehicle, the Fuel supply device with a quantity control valve and is provided with a high pressure pump, and wherein that Control device for controlling and / or regulating the Amount of fuel supplied to the internal combustion engine is provided is. The invention also relates to a Fuel supply device for an internal combustion engine in particular a motor vehicle with a Volume control valve, with a high pressure pump and with a Control device for controlling and / or regulating the Amount of fuel supplied to the internal combustion engine.

Such a method as well as such Control unit and such a fuel supply device are known from EP 481 964 A2. There it is  Quantity control valve opened when de-energized. Will that Volume control valve controlled, so it is closed and the high pressure pump delivers fuel for the subsequent one Injection of the same into the combustion chambers of the Internal combustion engine.

The object of the invention is a method of the beginning mentioned type, as well as a control unit and a Fuel supply device of the aforementioned Type in such a way that the most accurate Measuring the desired amount of fuel in the combustion chambers the internal combustion engine is possible.

This task is initiated in a procedure mentioned type solved by the invention in that the Volume control valve depending on one Battery voltage with which the volume control valve is acted upon and / or depending on one Coil resistance of the volume control valve is influenced. With a control unit or one Fuel supply device of the type mentioned is the object achieved by the invention in that the Volume control valve depending on the control unit from a battery voltage with which the volume control valve is acted upon and / or depending on one Coil resistance of the quantity control valve can be influenced.

The closing time of the volume control valve is in essentially represents the point in time from which fuel from the high pressure pump to the injectors and thus to the combustion chambers of the internal combustion engine is promoted. By the closing time of the volume control valve also the combustion chambers and thus the internal combustion engine fuel quantity influenced. The The closing time of the volume control valve itself is from depends on a number of sizes. So it will  Closing time sooner reached when the battery voltage, against which the volume control valve is located is large. Likewise there are dependencies of the closing time on the Coil resistance of the volume control valve, since this the Current determined by the volume control valve. According to the invention, these dependencies at Control of the quantity control valve is taken into account. So will in the invention, the dependence of the volume control valve battery voltage and / or coil resistance in the determination and resulting control of the volume control valve. This will make the Advantage achieved through the volume control valve influenced, supplied to the internal combustion engine Fuel quantity even with different Battery voltages and / or at different Coil resistances always correspond to the desired value. This increases the accuracy of the fuel metering improves, which is synonymous with a decrease of fuel consumption, as well as with a reduction of emitted pollutants.

In an advantageous development of the invention the coil resistance from a coil temperature of Volume control valve determined. It is therefore according to the invention not necessary to measure the coil resistance directly. Instead, it is sufficient to increase the coil temperature to capture. From this coil temperature can on Coil resistance can be closed. The coil temperature the flow control valve in turn can in particular advantageously from the cooling water temperature Internal combustion engine and / or from the intake air temperature the internal combustion engine can be determined.

In an advantageous embodiment of the invention the volume control valve depending on that of the High pressure pump affects the actual pressure generated. To this  Way is taken into account by the invention that the Closing the volume control valve and thus the The closing time of the volume control valve depends on the actual pressure generated by the high pressure pump. This is- Pressure acts on the volume control valve in the sense that he is closing the volume control valve supported. By taking this actual pressure into account the accuracy of the fuel metering with the Advantages already explained further improved.

In a further advantageous embodiment of the Invention will depend on the volume control valve affects the speed of the internal combustion engine. Especially when using a mechanical High pressure pump coupled to the internal combustion engine is, the speed of the internal combustion engine has a direct Influence on the high pressure pump. This is according to the invention taking into account that the speed of the Internal combustion engine or the high pressure pump in the Control of the volume control valve is received. Also through this measure will increase the accuracy of the metering Fuel on to the combustion chambers of the internal combustion engine improved.

The realization of the inventive method in the form of a Control that for a control unit one Internal combustion engine, in particular a motor vehicle, is provided. Here is on the control Program stored on a computing device, in particular on a microprocessor, executable and for Execution of the method according to the invention is suitable. In this case, the invention is based on a Control program stored so that this control provided with the program in the same The invention represents how the method for its  Execution the program is suitable. As a control can in particular be an electrical storage medium for Use, for example, a read-only memory.

Other features, applications and advantages of the Invention result from the following description of embodiments of the invention shown in the figures the drawing are shown. Thereby everyone described or illustrated features for themselves or in any combination the subject of the invention, regardless of their summary in the Patent claims or their relationship and independently from their formulation or representation in the description or in the drawing.

Fig. 1 is a schematic block diagram shows an embodiment of a fuel supply device according to the invention for an internal combustion engine;

FIG. 2 shows a schematic illustration of a high-pressure pump of the fuel supply device of FIG. 1 in three different operating states with an associated time diagram;

FIG. 3 shows a schematic block diagram of an exemplary embodiment of a method for operating the fuel supply device of FIG. 1;

FIG. 4 shows schematic time diagrams of signal profiles of the fuel supply device of FIG. 1; and

FIG. 5 shows a schematic flow diagram of a method that is complementary to the method of FIG. 3.

In FIG. 1, a fuel supply device 10 is shown, which is provided for operating an internal combustion engine. In particular, the fuel supply device 10 is suitable for use in an internal combustion engine with gasoline direct injection. In such an internal combustion engine, the gasoline is injected directly into the combustion chambers of the internal combustion engine in a so-called homogeneous operation during the intake phase and in a so-called stratified charge operation during the compression phase.

The fuel supply device 10 has an electric fuel pump 11 , with which the fuel is drawn in from a fuel tank 12 and conveyed further via a fuel filter 13 . The fuel pump 11 is suitable for generating a low pressure. To control and / or regulate this low pressure, a low pressure regulator 14 is provided, which is connected to the outlet of the fuel filter 13 and can be returned to the fuel tank 12 via the fuel.

The series circuit comprising a quantity control valve 15 and a mechanical high-pressure pump 16 is also connected to the output of the fuel filter 13 . The outlet of the high pressure pump 16 is returned to the inlet of the quantity control valve 15 via a pressure relief valve 17 .

The high pressure pump 16 is provided to generate a significantly higher high pressure than the low pressure generated by the electric fuel pump 11 . The pressure relief valve 17 is provided to discharge any overpressure that may arise. As will be explained below, the quantity control valve 15 is suitable for setting the quantity of fuel that is to be delivered by the high-pressure pump 16 .

The outlet of the high-pressure pump 16 is connected to a pressure accumulator 18 , to which a plurality of injection valves 19 are connected. The pressure accumulator 18 is often also referred to as a rail or common rail. Furthermore, a pressure sensor 20 is connected to the pressure accumulator 18 .

The injection valves 19 are assigned to the combustion chambers of the internal combustion engine. The fuel supply device 10 shown in FIG. 1 is thus provided for a four-cylinder internal combustion engine. The fuel is injected into the combustion chambers via the injection valves 19 . The amount of fuel that is injected into the associated combustion chambers via the individual injection valves is set via the volume control valve 15 .

In FIG. 2 the quantity control valve 15 and the high-pressure pump 16 is shown in more detail. The quantity control valve 15 has an electromagnet 21 with which a valve 22 can be opened and closed. The high pressure pump 16 has a piston 23 which is actuated by a cam 24 of the internal combustion engine. Furthermore, the high-pressure pump 16 is provided with a valve 25 .

A delivery chamber 26 of the high-pressure pump 16 is present between the valve 22 , the piston 23 and the valve 25 .

With the valve 22 , the delivery chamber 26 can be separated from a fuel supply by the electric fuel pump 11 and thus from the low pressure. With the valve 25 , the delivery chamber 26 can be separated from the pressure accumulator 18 and thus from the high pressure. In the initial state, as shown on the left in FIG. 2, the valve 22 is open and the valve 25 is closed. The opened valve 22 corresponds to the currentless state of the electromagnet 21 . The closed valve 25 is achieved by a corresponding spring or the like.

In the left view of FIG. 2 of the suction stroke of the high-pressure pump 16 is shown. When the cam 24 rotates in the direction of arrow 27 , the piston 23 moves in the direction of arrow 28 . Because of the opened valve 22 , fuel that has been delivered by the electric fuel pump 11 is thus sucked into the delivery chamber 26 .

The delivery stroke of the high-pressure pump 16 is shown in the middle of FIG. 2, but the electromagnet 21 is still de-energized and the valve 22 is still open. Due to the rotary movement of the cam 24 , the piston 23 moves in the direction of the arrow 29 . Because of the opened valve 22 , fuel is thus conveyed out of the delivery chamber 26 back towards the electric fuel pump 11 . This fuel then gets back into the fuel tank 12 via the low pressure regulator 14 .

The right-hand illustration of FIG. 2 shows the delivery stroke of the high-pressure pump 16 , as in the middle illustration. In contrast to the middle representation, however, the electromagnet 21 is now excited in the right representation and thus the valve 22 is closed. As a result, the piston 23 moved by the cam 24 in the direction of the arrow 29 now builds up a pressure in the delivery chamber 26 . This pressure opens the valve 25 against the force of the spring mentioned.

Fuel is thus conveyed from the piston 23 out of the delivery chamber 26 in the direction of the pressure accumulator 18 and thus in the direction of the injection valves 19 .

The amount of fuel delivered to the accumulator 18 depends on when the valve 22 changes to its closed state. The earlier the valve 22 is closed, the more fuel is fed into the pressure accumulator 18 via the valve 25 . This is shown in FIG. 2 by an area B marked with an arrow.

As soon as the piston 23 has reached its maximum piston stroke in the illustration on the right in FIG. 2, no further fuel can be conveyed by the piston 23 into the pressure accumulator 18 via the valve 25 . Due to the spring already mentioned, the valve 25 is closed again. Furthermore, the electromagnet 21 is controlled again without current, so that the valve 22 opens again. Thereupon, the piston 23 , which now moves in the direction of arrow 28, as shown in the left-hand illustration in FIG. 2, can again draw fuel of the electric fuel pump 11 into the delivery chamber 26 .

FIG. 3 shows a method for operating the fuel supply device 10 of FIG. 1. In particular, the method of FIG. 3 is intended to influence the quantity control valve 15 .

The method of FIG. 3 is carried out by a control device, not shown in detail. The control device has, in particular, a microprocessor which is suitable for processing programs. The blocks shown in FIG. 3 are implemented as such programs or program modules. The programs can be stored on an electronic memory, in particular on a read-only memory.

In Fig. 3 is a map 30 is shown, which are fed as input signals the rotational speed of the engine N and the voltage applied to the internal combustion engine load L. In function of the speed N and load L, the map 30 produces an output signal corresponding to a desired target pressure P corresponds _to the pressure accumulator in the eighteenth This setpoint pressure P _soll is compared with an actual actual pressure P _ist at a comparison point 31 . The actual pressure P _ist is measured by the pressure sensor 20 .

The difference between the target pressure P _soll and the actual pressure P _ist is fed to a delivery start control 32 . The start of delivery control 32 can be a conventional controller, for example a PI or PID controller.

The output signal of the start of delivery control 32 is fed to a control 33 , with which the electromagnet 21 of the quantity control valve 15 is controlled and thus the valve 22 of the high-pressure pump 16 is influenced. The controller 33 is provided to determine the transition of the electromagnet 21 from its de-energized to its energized state and thus the closing time of the valve 22 . With the aid of the controller 33 , it is thus possible to implement the area B explained in connection with FIG. 2. With the control 33 , the closing time and thus the amount of fuel delivered to the pressure accumulator 18 can thus be changed in the sense of area B.

The controller 33 is dependent on a plurality of input signals. Thus, the closing time of the valve 22 is changed as a function of a battery voltage UBatt, this battery voltage UBatt being used to supply energy to, inter alia, the electromagnet 21 of the quantity control valve 15 and the electromagnetic injection valves 19 . The closing time of the valve 22 is also dependent on the cooling water temperature TK of the internal combustion engine and on the intake air temperature TA of the internal combustion engine. The controller 33 can derive the coil temperature and thus the coil resistance of the electromagnet 21 from these temperatures. This coil resistance is taken into account by the controller 33 when determining the closing time of the valve 22 and thus the transition of the electromagnet 21 from its de-energized to its energized state. The control 33 and thus the closing time of the valve 22 is also dependent on the speed N of the internal combustion engine. This speed N corresponds directly or indirectly to the speed of the high pressure pump 16 . Furthermore, the closing time of the valve 22 is determined by the control 33 as a function of the actual actual pressure P _ist . A further dependency of the closing time of the valve 22 and thus the amount of fuel supplied to the pressure accumulator 18 is taken into account by the controller 33 with regard to the position of the cam 24 . From the position of the cam 24 , the controller 33 derives a measure of the speed of the piston 23 , which is used to determine the time for actuating the solenoid valve 21 and thus to determine the closing time of the valve 22 .

As the output signal, the control 33 generates a closing time signal t _a , with which the electromagnet 21 of the quantity control valve 15 is controlled and moved from its de-energized to its excited state and back. As a result, the closing time signal t _a determines the closing time of the valve 22 .

In FIG. 4, the closing timing signal is _a t shown in the top graph. During the period in which the closing time signal t _{a has} a voltage, the electromagnet 21 is energized and the valve 22 is closed. This time period t _a extends from time t ₁ to time t ₂ . After closing, fuel is thus conveyed from the delivery chamber 26 of the high-pressure pump 16 into the pressure accumulator 18 .

If the closing time signal t _{a has} a voltage, this has the consequence - as already explained - that the valve 22 is closed. This is shown in the second diagram in FIG. 4. The valve reaches its closed state at a time t ₃ , which is before the time t ₂ .

The current through the electromagnet 21 is plotted in the third diagram in FIG. 4. It can be seen from this diagram that the current increases substantially uniformly from time t ₁ to time t ₃ . Due to the stop of the valve 22 in its closed state, the current increases again more steeply between the times t ₃ and t ₂ . After the instant t ₂ , that is to say after the closing instant signal t _{a has} no voltage, the current drops again to 0.

The bottom diagram in FIG. 4 shows the pressure curve in the delivery chamber 26 of the high-pressure pump 16 . Initially, the low pressure ND generated by the electric fuel pump 11 prevails in the delivery chamber 26 . Due to the closing valve 22 and the movement of the piston 23 in the direction of arrow 29 in accordance with the illustration on the right in FIG. 2, the pressure in the delivery chamber 26 rises slowly. As a result, as already explained, the valve 25 opens. Thus, at time t ₃ , that is to say when the valve 22 is closed, the high pressure HD generated by the high pressure pump 16 prevails in the delivery chamber 26 of the high pressure pump 16 . This high pressure HD drops again after the end of the delivery stroke at time t ₄ .

It is possible that the valve 22 is stiff due to contamination or for some other reason and therefore does not move normally from its open to its closed state. This can result in the valve 22 not being closed at the time t ₃ . The closing time for the valve 22 determined by the control 33 and the resulting amount of fuel supplied to the pressure accumulator 18 are therefore no longer correct.

Such a malfunction of the valve 22 may, for example, by the controller 33 based on the measured by the pressure sensor 20 _is actual actual pressure P are detected in the pressure accumulator 18. As such, this actual pressure P _ist should remain approximately constant in the pressure accumulator 18 despite the injections that have taken place due to the amount of fuel supplied by the high-pressure pump 16 . However, if this is not the case, ie if the pressure in the pressure accumulator 18 drops significantly, in particular after an injection, then a malfunction of the valve 22 can be concluded therefrom.

In this case, the control 33 can additionally carry out the method shown in FIG. 5. With the method shown in FIG. 5, the closing time of the valve 22 , ie the time t ₂ in FIG. 4, is shifted to "later". This increases the current acting on the solenoid valve 21 . The result of this is that under certain circumstances the existing stiffness of the valve 22 can be overcome by the increased current. At the same time, an overcurrent shutdown is integrated in the method according to FIG. 5.

The method of FIG. 5 is based on a closing timing signal with the activation duration t _a = t _a0 of that example. Is determined in the manner described by the controller 33. A predetermined safety margin can also be taken into account for this activation duration t _a . The control duration t _a is a predetermined start value. According to FIG. 5, the drive duration t is _a defined in a block 34.

In a subsequent block 35 it is checked whether the current through the electromagnet 21 exceeds a predetermined maximum value. If this is the case, a diagnostic bit F is set to "1". If this is not the case, the diagnostic bit F remains at "0".

If the current through the electromagnet 21 has not exceeded the predetermined maximum value, that is to say F = 0, the actuation duration t _{d is increased} in a block 36 and the time t _{2 is} thus shifted to "later". This is done using the equation t _a = t _a + Δt. The method then continues again with block 35 .

However, if it is determined in block 35 that the current through the solenoid valve 21 has exceeded the predetermined maximum value, that is to say the diagnostic bit F is set to "1", the method is continued with block 37 . The control duration t _{a is} reduced in block 37 and the time t _{2 is} thus shifted to “earlier”. This is done using the equation t _a : = t _a - Δt.

In a block 38 following the block 37 , it is checked whether the activation time t _a has fallen below a predetermined minimum value. This is done using the query t _a ≦ t _amine . The specified minimum value t _amine corresponds to a minimum activation duration, which cannot be less than the design.

If the query of block 38 is answered with "no", that is to say the activation time t _{a is} not less than the minimum value t _amin , the method of FIG. 5 is continued again with block 35 . However, if the activation time t _{a has fallen} below the minimum value t _amin , ie if the query of block 38 is positive, an error is registered by means of block 39 and reported if necessary. This fault is then a short circuit on valve 22 .

The above-mentioned overcurrent shutdown is implemented by block 35 . The block 35 prevents the current through the electromagnet 31 from exceeding the predetermined maximum value. At the same time, block 38 ensures that the electromagnet 21 is always actuated with a closing time signal with the actuation duration t _a , which represents a useful value from a design point of view.

By the method in Fig. 5, the electromagnet 21 is always driven with the maximum current that the control unit can provide. If, even with this flow, the valve 22 cannot be closed due to stiffness, the error is determined by the pressure drop in the pressure accumulator 18 .

Reference list

10th

Fuel supply device

11

Electric Fuel Pump

12th

Fuel tank

13

Fuel filter

14

Low pressure regulator

15

Volume control valve

16

mechanical high pressure pump

17th

Pressure relief valve

18th

Pressure accumulator

19th

Injectors

20th

Pressure sensor

21

Electromagnet

22

Valve

23

piston

24th

cam

25th

Valve

26

Funding area

27

Arrow, cam

24th

28

Arrow, piston

23

29

Arrow, piston

23

30th

Map

31

Cold junction

32

Start of funding scheme

33

control

34

Definition of closing time

35

Compare current through

21

36

Increase of t _a

37

Reduction of t _a

38

Comparison with minimum

39

error

Claims (13)

1. A method for operating a fuel supply device ( 10 ) of an internal combustion engine, in particular a motor vehicle, in which the fuel quantity supplied to the internal combustion engine is controlled and / or regulated by means of a quantity control valve ( 15 ) and a downstream high pressure pump ( 16 ), characterized in that the quantity control valve ( 15 ) as a function of a battery voltage (UBatt) with which the quantity control valve ( 15 ) is applied and / or as a function of a coil resistance of the quantity control valve ( 15 ). 2. The method according to claim 1, characterized in that the coil resistance is determined from a coil temperature of the quantity control valve ( 15 ). 3. The method according to any one of claims 1 or 2, characterized in that the quantity control valve ( 15 ) is influenced as a function of the actual pressure (Pist) generated by the high pressure pump ( 16 ). 4. The method according to any one of claims 1 to 3, characterized in that the quantity control valve ( 15 ) is influenced as a function of the speed (N) of the internal combustion engine. 5. The method according to any one of the preceding claims, characterized in that the amount of fuel supplied to the internal combustion engine is influenced by a transition of the quantity control valve ( 15 ) from its de-energized to its energized state. 6. The method according to claim 5, characterized in that a valve ( 22 ) is closed by the transition of the quantity control valve ( 15 ) from its de-energized to its energized state. 7. The method according to any one of the preceding claims, characterized in that the actual pressure produced by the high pressure pump (16) _(P) to a target pressure (P _soll) is controlled and / or regulated. 8. The method according to any one of the preceding claims, characterized in that the flow through the quantity control valve ( 15 ) is limited to a maximum value. 9. control element, in particular read-only memory, for a control unit of a power supply device ( 10 ) of an internal combustion engine, in particular a motor vehicle, on which a program is stored which can be run on a computing device, in particular on a microprocessor, and for executing a method according to a of claims 1 to 8 is suitable. 10. Control device for a fuel supply device ( 10 ) an internal combustion engine, in particular a motor vehicle, the fuel supply device ( 10 ) being provided with a quantity control valve ( 15 ) and with a high-pressure pump ( 16 ), and wherein the control device for controlling and / or regulating the internal combustion engine The quantity of fuel supplied is provided, characterized in that the quantity control valve ( 15 ) can be influenced by the control device as a function of a battery voltage (UBatt) with which the quantity control valve ( 15 ) is applied and / or as a function of a coil resistance of the quantity control valve ( 15 ) is. 11. Fuel supply device ( 10 ) for an internal combustion engine, in particular of a motor vehicle, with a quantity control valve ( 15 ), with a high pressure pump ( 16 ) and with a control device for controlling and / or regulating the quantity of fuel supplied to the internal combustion engine, characterized in that the quantity control valve ( 15 ) can be influenced by the control device as a function of a battery voltage (UBatt) with which the quantity control valve ( 15 ) is applied and / or as a function of a coil resistance of the quantity control valve ( 15 ). 12. Control device or fuel supply device ( 10 ) according to claim 10 or claim 11, characterized in that the quantity control valve ( 15 ) can be influenced by the control device as a function of the actual pressure (Pist) generated by the high pressure pump ( 16 ). 13. Control device or fuel supply device ( 10 ) according to claim 10 or claim 11, characterized in that the quantity control valve ( 15 ) can be influenced as a function of the speed (N) of the internal combustion engine.