CN-121993308-A - Method for actuating a fuel injector, fuel system, computing unit and computer program

Abstract

The invention relates to a method for actuating a fuel injector of an internal combustion engine, comprising a magnetic actuator for actuating an outwardly open valve element, comprising a magnetic coil and a magnetic armature operatively connected to the valve element, and the magnetic coil being provided for applying an electrical current for opening the valve element. The method includes determining a target manipulation end time and a target manipulation duration of the magnetic actuator based on a target manipulation start time and a target fuel amount of the magnetic actuator, determining a cylinder pressure expected to act on the valve element at the target manipulation end time of the magnetic actuator, determining whether an expected closing start time of the valve element is located within a holding current phase of the magnetic coil for the determined cylinder pressure acting on the valve element, and increasing a current level of the magnetic coil in the holding current phase if the expected closing start time of the valve element is determined to be located within the holding current phase of the magnetic coil.

Inventors

• A.S.Z. Schweinsberg
• O. Turk

Assignees

• 罗伯特·博世有限公司

Dates

Publication Date

20260508

Application Date

20251104

Priority Date

20241104

Claims (14)

1. 1. A method for actuating a fuel injector (1) of an internal combustion engine, comprising a magnetic actuator (10) for actuating an outwardly opening valve element (4, 6), wherein the magnetic actuator (10) comprises a magnetic coil (3) and a magnetic armature (2) operatively connected to the valve element (4, 6), and wherein the magnetic coil (3) is provided for applying an electrical current for opening the valve element (4, 6), The method comprises the following steps: determining (101) a target manipulation end time and a target manipulation duration of the magnetic actuator (10) based on a target manipulation start time and a target fuel amount of the magnetic actuator (10); Determining (102) a cylinder pressure expected to act on the valve element (4, 6) at a target end of actuation of the magnetic actuator (10); Determining (103) whether an expected closing start time (t VNC ) of the valve element (4, 6) is located within a holding current phase of the magnetic coil (3) for the determined cylinder pressure acting on the valve element (4, 6); If it is determined that the expected closing start time (t VNC ) of the valve element (4, 6) is located within a holding current phase of the magnetic coil (3), the current level of the magnetic coil (3) in the holding current phase is increased (106).
2. 2. The method according to claim 1, wherein the expected closing start time (t VNC ) is determined (103) from at least one stored closing start time (t VNC ), wherein the at least one stored closing start time (t VNC ) is determined (200) for the cylinder pressure acting on the valve element (4, 6) at the target end-of-maneuver.
3. 3. The method according to claim 2, Wherein the at least one stored closing start time (t VNC ) is determined (200) from a regulating frequency (F R ) of a current regulation of a magnetic coil (3) of the fuel injector (1), or Wherein the at least one stored closing start time (t VNC ) is determined (200) from a degaussing duration (t L ) of a current (I MV ) in a magnetic coil (3) of the fuel injector (1).
4. 4. A method according to claim 2 or 3, wherein the at least one stored closing start time (t VNC ) comprises a plurality of stored closing start times (t VNC ) for different cylinder pressures acting on the valve element (4, 6) at the target manoeuvre end time.
5. 5. A method according to claim 2 or 3, wherein the at least one stored closing start time (t VNC ) comprises a plurality of stored closing start times (t VNC ) for different cylinder pressures and different fuel pressures acting on the valve element (4, 6) at the target manoeuvre end time.
6. 6. The method according to any of the preceding claims, wherein increasing (106) the current level of the magnetic coil (3) during the holding current phase comprises: The current level of the magnetic coil (3) during the holding current phase is increased (106) for a predetermined time before the closing start time (t VNC ).
7. 7. The method of the preceding claim, wherein increasing (106) the current level of the magnetic coil (3) during the holding current phase for a predetermined time before the closing start time (t VNC ) comprises: The current level of the magnetic coil (3) during the holding current phase is stepped up (106) for a predetermined time before the closing start time (t VNC ).
8. 8. The method of any of the preceding claims, further comprising: Determining a temperature of the magnetic coil (3) from an adjustment frequency (F R ) of a current adjustment of the magnetic coil (3) during a boost current phase of the magnetic coil (3), wherein increasing (106) a current level of the magnetic coil (3) during the hold current phase comprises: -increasing (106) the current level of the magnetic coil (3) during the holding current phase in dependence of the temperature of the magnetic coil (3).
9. 9. The method according to any one of the preceding claims, which is performed for each fuel injector (1) of the internal combustion engine.
10. 10. The method of claim 9, wherein increasing (106) the current level of the magnetic coil (3) during the holding current phase comprises: Increasing (106) the current level of a solenoid (3) of a fuel injector (1) for which it is determined that the expected closing start time (t VNC ) of the valve element (4, 6) is located during the hold-current phase of the solenoid (3), or The current level of the electromagnetic coils (3) of all fuel injectors (1) is increased (106).
11. 11. A computing unit arranged to perform all method steps of the method according to any of the preceding claims.
12. 12. A fuel system having: At least one fuel injector (1) having a magnetic actuator (10) for actuating an outwardly opening valve element (4, 6), wherein the magnetic actuator (10) has a magnetic coil (3) and a magnetic armature (2) which is operatively connected to the valve element (4, 6), and the magnetic coil (3) is provided for being supplied with a current (I MV ) for opening the valve element (4, 6), and The computing unit of claim 11.
13. 13. A computer program product which, when run on a computing unit of a fuel system according to claim 12, causes the computing unit to perform all the method steps of the method according to any one of claims 1 to 10.
14. 14. A machine readable storage medium having stored thereon the computer program product of claim 13.

Description

Method for actuating a fuel injector, fuel system, computing unit and computer program Technical Field The invention relates to a method for actuating a fuel injector of an internal combustion engine, a computing unit and a computer program for carrying out the method, and a fuel system. Background Because gaseous fuels for internal combustion engines, particularly hydrogen, have a relatively low volumetric energy density, these fuels typically require high flow injectors in order to provide the amount of fuel required for maximum power within the allowable time frame of the operating cycle of the internal combustion engine. However, the large flow cross section or valve needle travel of the injectors thus produced may lead to inaccurate fuel metering when the internal combustion engine is operated at part load. In order to avoid an excessively high flow of the injector with the above-mentioned disadvantages, it is advantageous to increase the permissible time range in the operating cycle of the internal combustion engine in which fuel can be injected into the internal combustion engine, so that the actuation duration of the injector can be prolonged. The allowable time range is generally defined by the earliest possible injection start time and the latest possible injection end time. The earliest possible start of injection is due to the possible pre-ignition of the fuel-air mixture in the intake tract of the internal combustion engine. Thus, injection is typically initiated only shortly before or immediately after intake valve closure. In the presently used injector designs with outwardly opening (relative to the space closed by the valve element) valve elements, the latest possible end of injection time is limited by the magnetic force required to keep the valve element open against the rising cylinder pressure in the engine cylinder during the compression stroke. It may be advantageous here to inject fuel as late as possible in the compression stroke, since this may reduce the tendency for knocking and reduce the compression work. Disclosure of Invention According to the invention, a method for actuating a fuel injector of an internal combustion engine, a computing unit and a computer program for carrying out the method, and a fuel system are proposed, having the features of the independent claims. Advantageous designs are the subject matter of the dependent claims and the following description. The fuel system according to the invention comprises one or more fuel injectors, each having a magnetic actuator for operating an outwardly (relative to the space closed by the valve element) opening valve element. The fuel injector may in particular be a gas injector, which is provided for injecting gaseous fuel, in particular hydrogen, directly into a cylinder of the internal combustion engine. Any other type of fuel injector having an outwardly opening valve element is also possible. The magnetic actuator of each fuel injector has a magnetic coil configured for application of an electrical current to open the valve element, and a magnetic armature operatively connected to the valve element. The valve element may in turn co-operate with a valve seat in the fuel injector housing. For example, the valve element may be a valve needle which has a closing element at one end, which may be designed, for example, as a valve disk and may be provided for releasing and closing the flow cross section at the valve seat. In the closed position of the fuel valve, the closing element may be held on the valve seat by a valve spring. Each fuel injector may also include a return element that maintains the magnetic armature in an idle position. The restoring element can likewise be designed as a spring, in particular as a helical spring. Furthermore, the fuel system comprises a computing unit, which may be in particular a motor controller of the internal combustion engine, and which is provided for actuating the fuel injectors. When the magnetic coil of the fuel injector is energized on the basis of a corresponding actuation signal of the computing unit, a magnetic field is formed, the magnetic force of which moves the magnetic armature in the direction of the closing element. The magnetic armature can be in contact with the valve element, so that the valve element can be lifted from the valve seat against the spring force of the valve spring, so that the flow cross section is opened. To fully open the fuel injector, the magnetic armature may move up to the travel stop. The energization of the magnet coil can be performed according to a defined current profile, which can be controlled by a computing unit. The calculation unit may, for example, determine a target manipulation start timing (at which the magnetic coil starts to be energized), a target manipulation duration (during which the magnetic coil is maintained energized), and a target manipulation end timing (at which the magnetic coil is energized ends), and output it to th