EP2724011B1 - Method and apparatus for controlling a fuel supply pump of an internal combustion engine - Google Patents

Description

State of the art

The invention relates to a method according to the preamble of claim 1, as well as an internal combustion engine which is designed to carry out the method and a computer program comprising commands which, when they run in the control and / or regulating device of the device, cause the device carries out the procedural steps.

Quantity control valves, for example in a fuel delivery device of an internal combustion engine, are known from the market. Quantity control valves are generally operated electromagnetically and are often an integral part of a high-pressure pump of the fuel delivery device. The quantity control valve controls the amount of fuel pumped to a high pressure accumulator ("rail"), from where fuel is directed to the injection valves of the internal combustion engine. An armature coupled to a valve body of the quantity control valve can be moved by magnetic force. The valve body - usually an inlet valve of the high-pressure pump - can strike against a valve seat or be lifted off the valve seat. As a result, an amount of fuel in the internal combustion engine can be regulated.

A patent publication in this field is, for example EP 1 042 607 B1 .

From the document EP 1 234 971 A2 a quantity control valve is known which is designed as a proportional valve. A valve closure can be moved over a whole range of closure positions, which is dependent on a current signal.

From the document WO 00/06894 A1 a quantity control valve is known in which an energization of a coil is determined as a function of the pump speed.

From the document JPH 2000-136747A a corresponding valve is known in which the current is determined as a function of the speed.

From the document DE 10 2004 016 554 A1 a quantity control valve is known in which an energy supplied for switching remains the same during a pick-up phase at high or low speeds. In addition, a current is constant during the pick-up phase. The invention is based on this.

Disclosure of the invention

The problem on which the invention is based is provided by a method according to claim 1 and by a device with means and a control and / or regulating device of an internal combustion engine, which are designed to carry out the method, and a computer program comprising commands that, when they are in Run control and / or regulating device of the device, cause the device to carry out the method steps, solved. Advantageous further developments are given in the subclaims. Features that are important for the invention can also be found in the following description and in the drawings, wherein the features can be important for the invention both on their own and in different combinations, without explicit reference being made to this again.

The method according to the invention has the advantage that a quantity control valve (metering device) of a fuel delivery device - especially during an internal combustion engine is operated at medium or low speeds - can be controlled with comparatively little electrical energy. The operating noise of the quantity control valve can be reduced and the fatigue strength increased.

The invention relates to a method for operating a fuel delivery device of an internal combustion engine, in which an electromagnetic actuating device of a quantity control valve arranged in an inlet to a delivery chamber of the fuel delivery device is switched to set a delivery rate. For this purpose, the electromagnetic actuation device is supplied with energy by means of the control during each switching process in which an armature is to be moved in the direction of a stroke stop. For example, the quantity control valve is switched twice, three times or even four times during one revolution of a camshaft of the internal combustion engine. For reliable switching of the quantity control valve and for achieving short switching times even at the highest possible speed of the camshaft or the internal combustion engine, comparatively high energies are required.

The invention is based on the consideration that at speeds below the maximum speed the requirement for a short switching time is correspondingly less critical. Thus, according to the invention, the strength of the energy supplied to the electromagnetic actuating device for switching, in particular a current supplied to the electromagnetic actuating device and / or a level of a voltage applied to the electromagnetic actuating device, is made at least temporarily dependent on a speed of the camshaft or the internal combustion engine, namely in that it is less at low speeds than at high speeds.

One embodiment of the method provides that the energy depends on the speed of the internal combustion engine only during a tightening phase, during which the armature of the electromagnetic actuating device is moved from a first to a second position. The pick-up phase requires a lot of energy in order to achieve the required short switching time. The dependency of the control according to the invention on the speed of the internal combustion engine during the starting phase is therefore particular efficient. The activation of the electromagnetic actuating device during a holding phase following the tightening phase can take place essentially independently of the speed.

It is also provided that the energy is increased with increasing speed, the relationship being monotonic. This takes into account that the armature must generally move faster in accordance with the speed. This is preferably done using a continuous and monotonic characteristic.

In particular, it is provided that the energy is controlled in such a way that the quantity control valve can be safely switched within a time interval provided for a respective speed. The time interval is generally greater for lower speeds than for higher speeds, and is dimensioned in each case so that the quantity control valve can work correctly. According to the invention, the time leeway that this allows is used to lengthen the tightening time of the armature at low speeds within the respective time interval. This requires less energy in each case.

One embodiment of the method provides that the current and / or the voltage are clocked to control the electromagnetic actuating device. For example, the electromagnetic actuation device is connected to an operating voltage by means of an electronic switch several times during the tightening phase and / or the holding phase of the armature and then switched off again. A pulse duty factor set in this way thus determines the average current during control. The pulse duty factor is set in such a way that the average current depends on the speed of the internal combustion engine in a manner according to the invention. The electronic switch is preferably actuated as a function of a lower and an upper current threshold. When the current flowing through a coil of the electromagnetic actuating device falls below the lower current threshold, the electronic switch is closed and the coil is thus connected to the operating voltage. As a result, the current flowing through the coil - and the resulting magnetic force - increases continuously. When the current flowing through the coil exceeds the upper current threshold, the electronic switch is opened and thus the coil is switched off from the operating voltage. As a result, the current flowing through the coil - and accordingly the magnetic force - is continuously reduced. In general, the current thresholds used for the pull-in phase and the holding phase are each different.

As an alternative to the use of current thresholds, it is also possible to control the electromagnetic actuating device by means of a “pre-controlled” pulse-width modulated voltage, the determining parameters for each at least one control being set in advance. According to the invention, these parameters are set so that the strength of the energy supplied to the electromagnetic actuating device for switching depends at least temporarily on the speed of the internal combustion engine.

The method is particularly easy to carry out if it is carried out by means of a computer program on a control and / or regulating device (“control unit”) of the internal combustion engine. In a preferred embodiment, the control device is set up by loading the computer program with the features of the independent computer program claim from a storage medium. To this extent, the storage medium is understood to mean any device that contains the computer program in stored form.

Figur 1

ein vereinfachtes Schema einer Kraftstofffördereinrichtung einer Brennkraftmaschine;

Figur 2

eine Schnittdarstellung einer Hochdruckpumpe der Kraftstofffördereinrichtung zusammen mit einem Mengensteuerventil und einer elektromagnetischen Betätigungseinrichtung;

Figur 3

ein Zeitdiagramm einer Ansteuerung der elektromagnetischen Betätigungseinrichtung;

Figur 4

ein Diagramm eines Anzugsstroms und einer Anzugszeit über einer Drehzahl der Brennkraftmaschine; und

Figur 5

ein vereinfachtes Blockdiagramm zur ergänzenden Darstellung des Verfahrens.

Exemplary embodiments of the invention are explained below with reference to the drawing. In the drawing show:

Figure 1

a simplified scheme of a fuel delivery device of an internal combustion engine;

Figure 2

a sectional view of a high pressure pump of the fuel delivery device together with a quantity control valve and an electromagnetic actuator;

Figure 3

a timing diagram of a control of the electromagnetic actuator;

Figure 4

a diagram of a pull-in current and a pull-in time over a speed of the internal combustion engine; and

Figure 5

a simplified block diagram to supplement the illustration of the method.

The same reference symbols are used for functionally equivalent elements and sizes in all figures, even in different embodiments.

Figure 1 shows a fuel delivery device 1 of an internal combustion engine in a greatly simplified representation. Fuel is supplied from a fuel tank 3 via a suction line 4, by means of a pre-feed pump 5, via a low-pressure line 7, and via a quantity control valve 10 which can be actuated by an electromagnetic actuating device 9 ("electromagnet") to a high pressure pump 11 (not further explained here). Downstream, the high-pressure pump 11 is connected to a high-pressure accumulator 13 (“common rail”) via a high-pressure line 12. Other elements, such as valves of the high pressure pump 11, are in the Figure 1 not drawn. The electromagnetic actuating device 9 is activated by a control and / or regulating device 16 on which a computer program 18 can run.

It goes without saying that the quantity control valve 10 can also be designed as a structural unit with the high-pressure pump 11. For example, the quantity control valve 10 can be a positively openable inlet valve of the high pressure pump 11. Alternatively, the quantity control valve 10 can also have an actuating device other than the electromagnet 9, for example a piezo actuator.

When the fuel delivery device 1 is in operation, the prefeed pump 5 delivers fuel from the fuel tank 3 into the low-pressure line 7. The quantity control valve 10 controls the amount of fuel supplied to a working chamber of the high-pressure pump 11 by moving an armature of the electromagnet 9 from a first to a second position - and vice versa becomes. The quantity control valve 10 can thus be closed and opened.

Figure 2 shows a partial sectional view (longitudinal section) of the high pressure pump 11 of the fuel delivery device 1 together with the quantity control valve 10 and the electromagnetic actuation device 9. The arrangement shown comprises a housing 20 in which the electromagnetic actuation device 9 in the upper area in the drawing and the quantity control valve in the middle area 10, and a delivery chamber 22 together with a piston 24 of the high pressure pump 11 are arranged in the lower region.

The electromagnetic actuating device 9 is arranged in a valve housing 26 and comprises a coil 28, an armature 30, a pole core 32, an armature spring 34, a resting seat 36 and a stroke stop 38. The resting seat 36 represents the first position of the armature 30, and the stroke stop 38 represents the second position of the armature 30. The armature 30 acts on a valve body 42 by means of a coupling element 40. In the drawing above the valve body 42, an associated sealing seat 44 is arranged. The sealing seat 44 is part of a pot-shaped housing element 46 which, among other things, encloses the valve body 42 and a valve spring 48. Sealing seat 44 and valve body 42 form the inlet valve of high pressure pump 11.

Is shown in the Figure 2 the de-energized state of the electromagnetic actuating device 9. The armature 30 is pressed downward against the resting seat 36 in the drawing by means of the armature spring 34. As a result, the valve body 42 is acted upon via the coupling element 40 against the force of the valve spring 48, whereby the inlet valve or the quantity control valve 10 opens. This creates a fluidic connection between the low-pressure line 7 and the delivery chamber 22.

In the energized state of the electromagnetic actuating device 9, the armature 30 is magnetically attracted by the pole core 32, whereby the coupling element 40 connected to the armature 30 is moved upward in the drawing. As a result, with appropriate fluidic pressure conditions, the valve body 42 can be pressed against the sealing seat 44 by the force of the valve spring 48, and the inlet valve or the quantity control valve 10 thus close. This can be done, for example, when the piston 24 is in the Delivery chamber 22 performs a working movement (upward in the drawing), with fuel being able to be delivered into the high-pressure line 12 via a non-return valve 60 that is open in the process.

The opening or closing of the quantity control valve 10 takes place as a function of several variables: Firstly, as a function of the forces exerted by the armature spring 34 and the valve spring 48. Secondly, depending on the fuel pressure prevailing in the low-pressure line 7 and the delivery chamber 22. Thirdly, it depends on the force of the armature 30, which is essentially determined by a current I currently flowing through the coil 28. In particular, the current I - again also depending on the respective fuel pressures - can influence the time of opening or closing of the valve body 42 and thus significantly control the amount of fuel to be delivered.

Figure 3 shows a timing diagram of a control of the quantity control valve 10. In the coordinate system shown in the drawing, currents I1 (solid) and I2 (dashed), which flow via the coil 28 of the electromagnetic actuator 9, are plotted over a time t. A double arrow 62 indicates the current supply for a tightening phase and a double arrow 64 indicates the current supply for a holding phase of the armature 30 of the electromagnetic actuating device 9. During the tightening phase, the armature 30 is moved by magnetic force from the resting seat 36 to the stroke stop 38. During the holding phase, the armature 30 is held in its position by a — generally lower — magnetic force on the stroke stop 38. The following describes the course of the current I1, which occurs at a comparatively high speed 72 (cf. Figure 4 ) the internal combustion engine is used to control the electromagnetic actuating device 9.

The pick-up phase begins at a point in time t0, the current I1 rising comparatively quickly and being clocked around a mean value 66a from a point in time t1a. The energization for the holding phase begins at a point in time t2, the current I2 being clocked around a mean value 68. The mean value 68 is smaller than the mean value 66a. The control is ended at a point in time t3, as a result of which the current I1 is rapidly reduced to zero.

At a lower speed 72 of the internal combustion engine, the electromagnetic actuator 9 is controlled with the current I2, that is, switching thresholds (not shown), which control the switching on and off of the current I2 during the pick-up phase, are lower in relation to the switching thresholds of the current I1 set. This results in a correspondingly smaller mean value 66b for the course of the current I2 during the pull-in phase. Thus, the energy required during the tightening phase is also smaller, and operating noise when the armature 30 hits the stroke stop 38 is reduced. At the same time, a tightening duration of the armature 30 is extended, the time difference between t2 and t0 being increased and the tightening phase 62 thus being extended, but without impairing the correct functioning of the quantity control valve 10.

The switching thresholds (not shown) that determine the courses of the currents I1 and I2, or the average values 66a and 66b resulting therefrom, are each selected in such a way that the armature 30 hits the stroke stop 38 reliably and thus the quantity control valve 10 switches reliably in all Operational cases is enabled. Due to the lower average current I2 during the pull-in phase, the armature 30 is accelerated with a lower force than the current I1 and strikes with a corresponding delay. This is explained below with the Figure 4 are explained in more detail.

Figure 4 shows a coordinate system in which mean values 66 of a current I flowing through coil 28 during the pick-up phase and associated pick-up times 70 are plotted linearly over a speed 72 of the internal combustion engine. The duration 70 characterizes the period from the beginning of the energization of the coil 28 at time t0 until the armature 30 strikes the stroke stop 38 for the first time. The mean values 66 are in the present case determined by support points 74, which, for example, in a characteristic map of the control and / or regulating device 16 of the internal combustion engine can be stored. The mean values 66 of the current I - in particular when the coil 28 is switched to a constant source voltage during the pull-in phase - also characterize an energy which is supplied to the electromagnetic actuating device 9 during the pull-in phase.

It can be seen that the mean values 66 of the current I increase monotonically with increasing speed 72. Because the piston 24 of the high-pressure pump 11 is also moved as a function of the speed 72, the possible period of time for the movement of the valve body 42 or the armature 30 is correspondingly smaller, that is to say more critical. This circumstance is counteracted in a suitable manner by the tightening times 70, which decrease with a higher current flow. As already described above, this takes place in such a way that reliable switching of the quantity control valve 10 is made possible at any speed 72.

Figure 5 shows a simplified flow chart for controlling the electromagnetic actuating device 9. The method shown is preferably carried out by means of the computer program 18 in the control and / or regulating device 16 of the internal combustion engine. The illustrated procedure begins in a first block 76, the current speed 72 of the internal combustion engine being determined. In a second block 78, two interpolation points 74 are read from a characteristic diagram based on the determined rotational speed 72. Thereafter, interpolation is carried out between these two support points 74 in order to determine a respective mean value 66 that is precisely matched to the speed 72. Suitable switching thresholds (without reference symbols) for switching the current I on and off are determined from the mean value 66.

In a third block 80, the determined switching thresholds are used to control the electromagnetic actuating device 9 or the coil 28 during the tightening phase of the armature 30. The procedure of Figure 5 can be repeated cyclically.

Claims (8)

1. Method for operating a fuel delivery device (1) of an internal combustion engine, in which in order to set a delivery quantity an electromagnetic activation device (9) of a quantity control valve (10) is switched, wherein during a switching process an armature (30) is moved from a rest seat (36) in the direction of a stroke stop (38), and the strength of energy which is fed to the electromagnetic activation device (9) for switching depends at least temporarily on a rotation speed (72) of the internal combustion engine, characterized in that the energy depends on the rotational speed of the internal combustion engine only during an attraction phase during which the armature (30) of the electromagnetic activation device (9) is moved from the rest seat (36) to the stroke stop (38), and during the attraction phase a current (I1) is clocked by an attraction mean value (66a), and during the holding phase a current (12) is clocked about a holding mean value (68), wherein the holding mean value (68) is lower than the attraction mean value (66a).
2. Method according to Claim 1, characterized in that the energy is increased as the rotational speed (72) rises, wherein the relationship is monotonous.
3. Method according to Claim 1 or 2, characterized in that the attraction mean values (66) of the current (I) increase monotonously as the rotational speed (72) becomes higher.
4. Method according to Claim 3, characterized in that the current (I) is increased as the attraction period (70) is reduced.
5. Method according to at least one of the preceding claims, characterized in that the energy is controlled in such a way that the quantity control valve (10) can be switched within a time interval which is provided for a respective rotational speed (72) .
6. Method according to at least one of the preceding claims, characterized in that the current (I) and/or the voltage are clocked.
7. Internal combustion engine having a fuel delivery device with a quantity control valve with electromagnetic activation device, an open-loop/closed-loop control apparatus and means for carrying out all the steps of a method according to one of Claims 1 to 6.
8. Computer program (18) comprising instructions that, when they run in the open-loop and/or closed-loop control apparatus (16) of the device according to Claim 7 cause the device to carry out the method steps according to Claims 1 to 6.

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