WO2018059819A1

WO2018059819A1 - Improving the cold-start behaviour of internal combustion engines

Info

Publication number: WO2018059819A1
Application number: PCT/EP2017/070652
Authority: WO
Inventors: Florian Herzenjak; Juergen Foerster; Christian Mengler; Thorsten Allgeier; Winfried Langer
Original assignee: Robert Bosch Gmbh
Priority date: 2016-09-30
Filing date: 2017-08-15
Publication date: 2018-04-05
Also published as: DE102016219015A1

Abstract

The invention relates to a method (100) for actuating an injection system (2) for an internal combustion engine (4), which is operated with fuel (3), of a motor vehicle (1), wherein the injection system (2) comprises a rail (21) out of which the fuel (3) is conducted through at least one injector (22-25) into an intake pipe (6, 62-65) leading to at least one combustion chamber (5, 52-55) or is conducted directly into the combustion chamber (5, 52-55), and wherein the injector (22-25) comprises a solenoid coil (22a-25a) and can be opened by energisation of the solenoid coil (22a-25a), wherein the solenoid coil (22a-25a) is energised with a current-time profile (26) starting with a current Ii (110), which is nominally sufficient for opening the injector (22-25), wherein monitoring (120) takes place as to whether the injector (22-25) opens, and, in response to the opening (130) or non-opening over a predefined time period to (140), the current-time profile (26) is reduced (150) to a current Io which is lower than needed to hold the injector (22-25) open. The invention also relates to an associated computer program product.

Description

Description Title:

Improvement of the cold start behavior of internal combustion engines

The present invention relates to a method for controlling a

Injection system in an internal combustion engine, which is operated with a, in particular gaseous, fuel.

State of the art

An internal combustion engine has one or more cylinders with a combustion chamber into which a precisely defined amount of fuel is to be injected at a precisely defined time in the cylinder duty cycle. For the metering of the fuel quantity injectors are used. All injectors together with their control form an injection system.

Injectors for gaseous fuels must have a particularly small leakage, so that the specified time-volume profile for the injection is maintained exactly. Instead of the metal-metal seals at the metering point customary for injectors for liquid fuels, metal-elastomer seals are therefore often used. At cold ambient temperatures, these seals tend to stick. If the opening force exerted when the injector is actuated is insufficient, in addition to the restoring force of the

Valve spring and the back pressure of the fuel rail to overcome the resistance caused by the gluing, the injector is not functional and the cold start endangered.

From EP 1 950 409 B1 is a method for driving a

Injection known, with the cold start of a bivalent, ie optionally operated with gasoline or gas, internal combustion engine can be facilitated. In this method, the internal combustion engine is initially started in gasoline mode, while the gas supply to the rail for gas operation is blocked. By those injectors that can be opened, the gas pressure in the rail is gradually released, the gas discharged is burned in the gasoline-gas mixing operation. If the rail is depressurized, the injectors are activated with a continuous current in order to heat them internally.

In a monovalent, i. only gas-powered, internal combustion engine, there is an even more urgent need to facilitate the cold start, since there is no possibility in a failure of the cold start to move the motor vehicle by its own power.

DISCLOSURE OF THE INVENTION Within the scope of the invention, a method for the control of a

Injection system for a fuel-powered internal combustion engine of a motor vehicle developed. The fuel may in particular be gaseous. The injection system comprises a feed, referred to below as rail, from which the fuel is guided through at least one injector into a suction pipe leading to at least one combustion chamber or directly into the combustion chamber. In this case, the injector can be arranged in the vicinity of the inlet valve leading into the combustion chamber (Multi Point Injection). The injector can also feed a mixer on the intake manifold before or after the throttle, from where the fuel is distributed to several cylinders (Central Point Injection).

The injector comprises a magnetic coil and is powered by the

Solenoid to open. Due to its ohmic resistance, the magnetic coil can be used as heater for the injector. The fuel may in particular be compressed natural gas (CNG).

According to the invention, the magnetic coil is subjected to a special current-time profile. This current-time profile starts with a current Ii that is nominal enough to open the injector. It is monitored whether the injector opens. In response to opening or failure to open over For a predetermined period of time to, the current-time profile is lowered to a current lo that is less than necessary to keep the injector open. The current lo may be zero in particular. A nonzero current can be used to constantly heat the injector with a certain base load.

In particular, the injector can be acted upon by a continuous current Ii, which is reduced to lo = 0 as soon as the injector opens or this opening has failed to occur over the predetermined period of time to.

The current Ii generated at the ohmic resistance R of the solenoid heat loss, which penetrates to the elastomer-metal seal and there ensures a temperature increase. Furthermore, the anchor exerts a permanent tensile force on the valve seat. As a result of both actions, the injector will open after some time and is also open for opening the following

Injection pulses better prepared.

It was recognized that this method does not necessarily rely on making the rail initially depressurized. The supply of the gaseous fuel to the rail can be opened in the usual way. Accordingly, the electrical heating of injectors, which initially can not be opened, can be started immediately. Furthermore, the injector is not heated longer than necessary by energizing. In sum, this has the advantageous consequence that it is not necessary to start the engine initially with gasoline.

Instead, opening problems of injectors can also be remedied on monovalent, purely gas-powered, internal combustion engines, with the only available energy source before starting the engine

Vehicle battery is. In the prior art, there were further attempts to permanently apply injectors with very low current intensities in order to generate kinetic energy or

Heating energy without actually opening the injector in this bring. Thus, currents that are sufficient to open the injector were deliberately avoided. It has now been recognized by the inventors that the

Heating the injector with the higher current Ii in conjunction with the Monitoring on the opening of the injector is much more effective and yet avoids the introduction of combustion relevant amounts of fuel in the combustion chamber: According to Ohm's law increases at the resistance of the R

Magnetic coil converted power square with the current I.

To pressurize the solenoid with the current-time profile, for example, a DC voltage can be applied at any time, which drives the currently required current through the ohmic resistance of the solenoid. This DC voltage can be taken for example from the vehicle battery or from a DC / DC converter. The currently required power can, however, also, for example, by turning on and off a higher

Voltage in rapid succession, analogous to the operation of a switched-mode power supply, can be realized as time average.

The monitoring of whether the injector opens, for example, via the rail pressure PR done. In a particularly advantageous embodiment of the invention, therefore, the current-time profile begins in time in a state in which the pressure PR in the rail is higher than the pressure PB on the injection side in the intake manifold or in the

Combustion chamber. A decrease in the pressure PR by at least a predetermined difference amount APR is evaluated as a signal for opening the injector.

It has been recognized that even when the supply of the fuel from the reservoir is active, the rail pressure PR drops at least briefly when the injector is opened. Since a sensor for the rail pressure PR is already installed in most existing injection systems, monitoring whether the injector opens does not require any additional hardware. The evaluation of the rail pressure PR can be carried out in particular in the engine control unit. The method may ultimately be implemented purely in software or firmware running on the engine control unit, for example. This software can

for example sold as a stand-alone product on the aftermarket.

A pressure difference between the rail pressure PR and the pressure PB on the injection side in the intake manifold or in the combustion chamber exists not only when the supply of the fuel from the reservoir to the rail is active. Is this feed locked, at least one residual pressure in the rail is present, since the fuel system is tight. So there is a free choice as to whether the fuel supply is activated or not. A recognition of the opening via the pressure drop further offers the advantage that in the case of several individual injectors per cylinder connected in parallel or in series, which are controlled jointly, it is possible to determine in a particularly simple manner how many individual injectors are open. If several identical individual injectors are controlled jointly, the pressure drop is proportional to the number of open injectors.

In a further advantageous embodiment of the invention, the opening of the injector is detected via a structure-borne sound signal. This is faster than that

Detection of the drop in rail pressure P _R at the cost of requiring an additional sensor that is not standard in fuel injection systems.

The magnet coil of each injector connected to the rail is advantageous in alternation with an injector-individual current-time profile

applied. The course of this current-time profile depends on whether and, if so, when the respective injector opens. If several injectors are present, they will typically be affected to varying degrees by adhesive bonding at cold ambient temperatures. The admission with a

Injector-individual current-time profile leads on the one hand, that the

Make the injectors not to an entry of

combustion relevant amounts of fuel into the combustion chamber leads. On the other hand, electrical energy is saved, the cold start of a

monovalent combustion engine can only come from the vehicle battery. If there is not enough energy stored for the starting process, the start finally failed.

For example, the solenoid coils of the injectors connected to the rail can be cyclically charged with their individual current-time profile, ie, the current-time profile of the next injector starts with the higher current Ii after the current-time profile of the previous Injectors on the low current lo has dropped. The signal for the opening, that is, for example, a drop in the rail pressure P _R or a structure-borne sound signal, can then always be assigned exactly to an injector. In particular, in the internal combustion engine, the injectors can be applied to several

Rail groups be divided, so be connected to different, not interconnected Rails. Examples of such engines are V-engines. If the opening of an injector in a rail group can be detected independently of other rail groups, so for example each

Rail group has its own pressure sensor, can be different

Rail groups belonging injectors are acted upon at the same time with their individual current-time profile. For example, the injectors of each rail group may be driven cyclically, and this may be done in parallel for the different rail groups to save time.

If several injectors have a mixer on the suction pipe before or after

Threshold throttle (Central Point Injection), compared to the Multi Point Injection, in which the injectors are arranged in the vicinity of the intake valves, the simplification that the assignment of the injectors to the individual cylinders must be disregarded.

In a particularly advantageous embodiment of the invention, the current-time profile is repeated injector-individual until a predetermined number of repetitions is reached and / or until a predetermined number of

Injectors in response to the energization has opened. These measures help conserve energy from the vehicle's battery and thus increase the likelihood that the starter will still find enough energy in the battery when it starts up.

In a particularly advantageous embodiment of the invention, the method is initiated in response to a request for starting the internal combustion engine, and the starter of the internal combustion engine is locked as long as the repetition of the current-time profiles is not yet completed. In this way it is avoided that a start attempt is made at a time for which he has no legitimate chance of success. Especially at cold temperatures, the state of charge of the vehicle battery is sufficient

possibly only for a few start attempts. When the starter is released, the injectors are then driven according to the normal injection scheme.

In an alternative particularly advantageous embodiment of the invention, the method is in response to a request to start the

Internal combustion engine initiated. At the same time, the starter of

Internal combustion engine released. This starts each current-time profile for the

Solenoid coil of an injector at the time when the injector should regularly open according to the injection cycle of the internal combustion engine. The advantage of this embodiment is that, when an injector opens, this injector can seamlessly transition to the regular operation and thus the engine start may be faster.

For this purpose, the lowering of the current-time profile from Ii to lo is advantageously delayed until the time when the injector according to the

Injection cycle of the internal combustion engine should close regularly. In other words, after opening the injector, the current supply is required

Injection time minus an amount for the detection time of opening extended, if the injection from this point still makes sense, so if, for example, the inlet valve is still open in Multi Point Injection. The loading of the injectors with the current-time profile can be done not only before the engine start, but also after the engine start, such as the engine ramp or engine warm running to opening problems to individual

To eliminate injectors and so the smoothness of the internal combustion engine

manufacture.

As already mentioned, the procedure can be carried out when the injectors full fuel pressure is applied. However, as an additional measure to make it particularly difficult to gluing impacted injectors can be locked in a further advantageous embodiment of the invention, the supply of fuel from the reservoir into the rail, as long the repetition of the current-time profiles has not yet been completed. Each time an injector is opened, the rail pressure PR continues to decrease and this pressure drop is not replenished. With the rail pressure PR, the back pressure, against which the injectors must open, gradually decreases. If the total number of injectors present in the internal combustion engine is distributed over several rail groups which are connected to rails which are not connected to one another, then for example only the supply to a rail can be shut off, to which injectors are connected which are particularly difficult to open.

In particular, in such a configuration with a plurality of rail groups, the supply of the fuel can advantageously be released prematurely in response to a load request to the internal combustion engine, and / or falls below a minimum pressure p _m in the rail.

The method can in principle be carried out at every engine start. However, the bonding preferably occurs at low outside temperatures. Therefore, in a particularly advantageous embodiment of the invention, the admission of the magnetic coil of the injector with the current-time profile made dependent on the ambient temperature T reaches or falls below a predetermined minimum value Tc. In particular, depending on the ambient temperature T, the specific configuration of the method can be selected: both the extent of the bond in the injectors and the amount of energy available from the vehicle battery are temperature-dependent.

In a further particularly advantageous embodiment of the invention, an internal combustion engine is selected in which at least one cylinder is supplied with fuel via at least two electrically jointly controlled individual injectors, which form an injector. When creating the current-time profile, it is recognized how many individual injectors open. As already mentioned, this detection via the drop in the rail pressure PR is particularly simple. As soon as it is recognized that at least one single injector opens, the current profile should advantageously drop from Ii to Io so that fuel does not escape in an uncontrolled manner through the open single injector. Even with truck engines, fuel systems with two or more individual injectors connected in parallel or in series are used. For example, when using car injectors (NGI2) as

Single injectors usually required to connect multiple injectors in parallel or in series to ensure the required fuel flow.

It is therefore not apparent which of the cylinders assigned

Single injectors open and which not. However, by ensuring a certain number of open single injectors, the correct functioning of the cylinder can be ensured.

For this purpose, for example, in response to at least one of the commonly controlled single injectors not opening, the

Engine control unit in engine operation to be induced in the following

Injection cycles the activation duration of the jointly controlled

To extend single injectors (i.e., the drive duration of the injector formed from these single injectors) to compensate for the lack of injection amount of fuel due to the non-opening.

In this way it can be ensured, in particular, that the mixture is within the burn limits. If the mixture is outside of the

Combustion limits, this leads to misfiring, poor emission levels or even to the non-start of the engine.

In general, at least one of the controlled individual injectors per cylinder results in one of the described positive effects, the other one

Single injector is prepared for opening at least. The starting characteristic of the engine is therefore improved on a statistical average.

To determine the number of open individual injectors, for example, the in driving the associated a first cylinder individual injectors caused drop in rail pressure P _R to the associated in driving the second or further cylinder individual injectors caused drop in rail pressure P _R are compared. For example, in the case of an internal combustion engine with three or more cylinders, only one cylinder falls out of the frame in such a way that when the individual injectors assigned to it are driven, the drop in the rail pressure P _R is lower, it can be seen that not all this cylinder associated with individual injectors are open.

In the same way it can also be determined that an originally unopened single injector could finally be brought to opening by heating with the current Ii, and / or by otherwise heating. Advantageously, then the extension of the driving time in

Motor operation reversed accordingly. In particular, the drive duration may be reset to its default value once it has been determined that all the injectors associated with the cylinder are opening, i.e., that the injector formed from these individual injectors is fully functional.

After the above, the invention may be wholly or partially implemented in software and, if already existing sensors can be used in the vehicle, be implemented entirely without hardware change. Therefore, the invention also relates to a computer program product with machine-readable instructions which, when executed on a computer or on an engine control unit, the computer or the

Cause the engine control unit to carry out a method according to the invention.

Further measures improving the invention will be described in more detail below together with the description of the preferred embodiments of the invention with reference to figures.

embodiments

It shows:

Figure 1 motor vehicle 1 with internal combustion engine 4, configured for the

Application of the method 100;

FIG. 2 is a flow chart of an embodiment of the method 100; FIG. 3, making an injector 22-25 pass through continuous energization;

Figure 4 Application of the method 100 to an internal combustion engine 4 with four injectors 22-25;

FIG. 5 compensation for an injector 24 comprising a functioning single injector and a bonded single injector.

According to Figure 1, the motor vehicle 1 includes a reservoir 31 for fuel 3. About a check valve 32, the fuel 3 to the rail 21 of the

Internal combustion engine 4 supplied.

The internal combustion engine 4 comprises four cylinders 42-45, each having a

Surround combustion chamber 52-55, and a controllable by the engine control unit 47 starter 41. Each combustion chamber 52-55 of the fuel 3 is metered via its own injector 22-25, by energizing a

Solenoid 22a-25a is open. In the example shown in FIG. 1, the fuel 3 is guided in each case through an injector 22-25 into a suction pipe 62-65 leading to the respective combustion chamber 52-55. Each solenoid coil 22a-25a is acted upon by the engine control unit 47 with an injector-individual current-time profile 26. The rail pressure PR is measured via the pressure sensor 46 and supplied to the engine control unit 47.

Figure 2 illustrates an embodiment of the method 100 as

Flowchart. The method is initiated by the request 105 for starting the internal combustion engine 4. In the query 101, it is first checked whether the ambient temperature T is less than or equal to the threshold Tc. If this is not the case (true value 0), the process is ended. If T <Tc, then in step 110, the solenoid coil 22a-25a of the injector 22-25 is supplied with the current Ii, which is sufficient to open the injector 22-25. In parallel, it is monitored in block 120 whether the injector opens 22-25. For this purpose, the drop of the rail pressure PR occurring during opening is evaluated in sub-block 122.

Alternatively or in combination thereto, in sub-block 124, the result of the stop of the injector 22-25 in its open end position

Structure-borne noise signal evaluated. The current I through the magnetic coil 22a-25a remains at the high level Ii until, in block 130, the opening of the injector 22-25 is detected or it is determined in block 140 that this opening has not remained for the predetermined period of time to. Each of these two events provides the opportunity, in block 150, to return the current I to the level lo, which is no longer sufficient to keep the injector 22-25 open.

The current-time profile 26 thus includes, from block 110, a first phase in which the current I is at the level Ii, and from block 150 a second phase, in which the current I is at the level lo. The cycle 160 framed in FIG. 2 is carried out for each of the injectors 22-25 connected to the rail 21 and repeated according to branching 170 until a predetermined number of times

Repetitions is reached and / or until a predetermined number of

Injectors 22-25 has opened in response to the energization.

FIG. 3a shows the dependencies l (t) of the injector flow I, x (t) of the injector stroke x, PR) of the rail pressure PR and m (t) of the injected fuel quantity m from the time t for an injector 22-25 which, when supplied with the current Ii immediately opens. The drop in the rail pressure p R (t) produced during opening supplies the cause 130 to return the current I to I 0 = 0, whereupon the injector 22- 25 closes again. Accordingly, the total amount of fuel 3 passed through the injector 22-25 increases from zero to a low level only for a very short time and then remains constant there.

FIG. 3b shows the time profiles 1 (t), x (t), pR (t) and m (t) shown in FIG. 3a in the event that the injector 22-25 is first adhesively bonded. As long as the injector 22-25 has not yet opened, the current I is kept at the level Ii. The drop in the rail pressure PR in turn provides the opportunity to reduce the current I to the level lo = 0. Analogous to FIG. 3a, only during a short period of time does a small amount m of fuel 3 pass through the injector 22-25.

For comparison only, Figure 3c shows the time lapses l (t), x (t), pR (t) and m (t) for a normal injection of fuel 3 through the injector 22-25 on the same scale as in Figures 3a and 3b , The injector 22-25 is essential here opened longer than in Figure 3b. Accordingly, the amount m (t) of the total injected fuel 3 increases and reaches a high level compared to FIGS. 3a and 3b. FIG. 4 shows the application of the method to an internal combustion engine 4 with four injectors 22-25. Plotted are the curves pR (t) of the rail pressure PR, l (t, 22-25) of the injector flows for the injectors 22-25, 41 (t) of the starter operation 41 and n (t) of the rotational speed n as a function of the time t. At time ts, the ignition is turned on (start request, step 105) and the rail pressure PR is established. This rail pressure PR breaks down momentarily whenever one of the injectors 22-25 opens.

The comparison with the injector streams I (t, 22-25) discloses the respective one

Behavior of injectors 22-25. The first injector 22 opens immediately when energized with the current Ii. Therefore, the current is immediately reduced back to the level lo = 0. The second injector 23 opens only after prolonged energization with the current Ii and corresponding heat and force; However, the injector 23 is finally brought to functioning by this measure. The third injector 24 opens after energizing the current Ii for the

Maximum to not. Therefore, the energization of this injector 24

aborted and passed over to the energization of the fourth injector 25. This in turn opens immediately.

Thus, a cycle 160 is complete, at the end of the injectors 22, 23 and 25 could be made to work. Only the injector 24 does not work yet. Nevertheless, after this cycle 160, the starter 41 is released and attempts to start with only three injectors. Subsequently, start-quantity injections 41a and 41b take place. The launch is ultimately successful; When the engine 4 starts, the engine speed n (t) increases rapidly. Thus, the starter 41 has become redundant and is turned off.

FIG. 5 shows a further exemplary embodiment of an internal combustion engine 4, in which four injectors 22-25 each consist of two parallel circuits

Single injectors (without reference numerals) are realized. Plotted are the time courses 41 (t) of the starter operation 41, 32 (t) of the switching position of Shut-off valve 32, pR (t) of the rail pressure PR and l (t, 22-25) of the injector streams for the injectors 22-25. First, both the starter 41 and the shut-off valve 32 are locked (operation or switching position 0), and the four injectors 22-25 are tested by short test pulses with the current Ii. In each case, it is evaluated whether the rail pressure pR (t) decreases and, if so, how strong.

Open all injectors 22-25, wherein the rail pressure pR (t) with each test opening progressively decreases further, because it is not refilled from the storage tank 31 because of the locked shut-off valve (32). When opening the injector 24, it is noticeable that the drop in the rail pressure p R (t) is only half as great as when opening the other injectors 22, 23 and 25 (illustrated by arrow A in FIG. 5). This shows that only one of the individual injectors connected in parallel, which together form the injector 24, opens.

With this knowledge, the starter 41 is released (operation 1). At the same time, the shut-off valve 32 is opened and thus the supply of the fuel 3 from the reservoir 31 is released. In the subsequent injections with the injectors 22-25, the drive duration (pulse width) of the injector 24 in

Compared to the drive duration of the other injectors 22, 23 and 25 doubled in order to inject the required amount of fuel 3 despite the halved throughput. Thus, despite the failure of a single injector in the cylinder an ignitable mixture is available, and a safe engine start is

guaranteed.

In an analogous manner to the test pulses, each injection of fuel 3 from one of the injectors 22-25 leads to a short-term drop in the rail pressure pR (t), the pressure drop for the injector 24 again being only half as large (in FIG. 5 by arrow B) illustrated). In contrast to the test pulses, however, the rail pressure p R (t) is repeatedly filled up to the nominal pressure P by the open shut-off valve 32.

Claims

claims

A method (100) for controlling an injection system (2) for an internal combustion engine (4) of a motor vehicle (1) powered by fuel (3), wherein the injection system (2) comprises a rail (21) from which the fuel (3 ) by at least one injector (22-25) in a at least one combustion chamber (5, 52-55) leading suction pipe (6, 62-65) or directly into the combustion chamber (5, 52-55) is guided, and wherein the Injector (22-25) comprises a magnetic coil (22a-25a) and is to be opened by energizing the magnetic coil (22a-25a), characterized in that the magnetic coil (22a-25a) with a current-time profile (26) acted upon which starts with a current Ii (110) nominally sufficient to open the injector (22-25), monitoring (120) whether the injector (22-25) opens, and in response to the opening (FIG. 130) or a failure to open for a predetermined period of time to (140) the current-time profile (26) is lowered to a current lo (150), the is less than necessary to keep the injector (22-25) open.

2. Method (100) according to claim 1, characterized in that the

Current-time profile (26) begins in time in a state in which the pressure PR in the rail (21) is higher than the pressure PB on the injection side in the intake manifold (6, 62- 65) or in the combustion chamber (5, 52 -55), wherein a decrease in the pressure PR by at least a predetermined difference amount APR is evaluated as the signal for opening the injector (22-25) (122).

3. The method (100) according to any one of claims 1 to 2, characterized

characterized in that the opening of the injector (22-25) via a

Structure-borne noise signal is detected (124).

4. The method (100) according to any one of claims 1 to 3, characterized

characterized in that the magnetic coil (22a-25a) of each on the rail (21) connected injector (22-25) in alternation with an injector-individual current-time profile (26) is acted upon (160).

5. The method (100) according to claim 4, characterized in that the

Injectors (22-25) of the internal combustion engine (4) are divided into a plurality of rail groups, wherein belonging to different rail groups injectors (22-25) are acted upon at the same time with their injector-individual current-time profile (160).

6. The method (100) according to any one of claims 4 to 5, characterized

characterized in that the current-time profile (26) is repeated injector-individually (170) until a predetermined number of repetitions have been reached and / or until a predetermined number of injectors (22-25) have opened in response to the energization.

7. Method (100) according to claim 6, characterized in that the

A method in response to a request (105) for starting the

Internal combustion engine (4) is initiated and that the starter (41) of the

Combustion engine (4) is disabled as long as the repetition of the current-time profiles (26) is not yet completed.

8. The method (100) according to any one of claims 1 to 6, characterized

characterized in that in response to a request (105) for starting the internal combustion engine (4) the method (100) is initiated and at the same time the starter (41) of the internal combustion engine (4) is released, each current-time profile (26) for the solenoid (22a-25a) of an injector (22-25) starts at the time when the injector (22-25) should regularly open according to the injection cycle of the engine (4).

9. Method (100) according to claim 8, characterized in that the

Lowering the current-time profile (26) is delayed from Ii to lo until the time when the injector (22-25) according to the injection cycle of the internal combustion engine (4) should close regularly.

10. The method (100) according to claim 6 and optionally one of claims 7 to 9, characterized in that the supply of fuel (3) from

Reservoir (31) is locked in the rail (21) as long as the repetition of the current-time profiles (26) is not yet completed.

11. The method (100) according to claim 10, characterized in that the

Supply of the fuel (3) in response to a load request to the

Internal combustion engine (4), and / or falls below a minimum pressure p _m in the rail (21), prematurely released.

12. The method (100) according to any one of claims 1 to 11, characterized in that the loading of the magnetic coil (22a-25a) of the injector (22-25) with the current-time profile (26) is made dependent (101 ) that the ambient temperature T reaches or falls below a predetermined minimum value Tc.

13. Method (100) according to claim 1, characterized in that an internal combustion engine (4) is selected, in which at least one cylinder (42-45) is connected to an injector (22 -25), with

Fuel (3) is supplied, which is detected when creating the current-time profile (26), how many individual injectors open.

14. Method (100) according to claim 13, characterized in that in response to at least one of the jointly controlled

Single injectors does not open, the engine control unit (47) is caused in engine operation to extend the driving time of the jointly controlled Einzelinjektoren in subsequent injection cycles to compensate for the lack of fuel due to the non-opening injection amount (3).

15. Computer program product containing machine-readable

Instructions that when on a computer or on a computer

Engine control unit (47) are executed, the computer or the

Causing the engine control unit (47) to perform a method (100) according to any one of claims 1 to 14.