Method for operating an internal combustion engine and corresponding internal combustion engine

Abstract

A method for operating an internal combustion engine having at least one fuel injection valve for introducing fuel into a combustion chamber of the internal combustion engine, the valve being supplied with a specified current intensity in order to adjust a specified flow cross-section of a fuel fluidic connection in the combustion chamber. The maximum specified current intensity during normal operation is equal to a first current intensity and during a release operation is equal to a second, higher current intensity.

Claims

1. A method for operating an internal combustion engine comprising at least one fuel injection valve for introducing fuel into a combustion chamber of the internal combustion engine, the method comprising: supplying the valve with a specific current intensity using pulse width modulation in order to set a specific throughflow cross section of a fuel flow connection into the combustion chamber, setting the specific current intensity to be equal to a first current intensity during a normal operating mode of the internal combustion engine and setting the specific current intensity to be equal to a second current intensity during a clearing operating mode, wherein the second specific current intensity is higher than the first specific current intensity, and the specific throughflow cross section is set at a maximum during the clearing operating mode, and the specific throughflow cross section is set to less than the maximum during the normal operating mode.

2. The method as claimed in claim 1, including carrying out the clearing operating mode before the normal operating mode.

3. The method as claimed in claim 2, including carrying out the clearing operating mode when the internal combustion engine is deactivated.

4. The method as claimed in claim 1, including performing the supplying of the fuel injection valve with the second current intensity so that a valve needle is moved out of a closed position in order to at least partially clear the fuel flow connection.

5. The method as claimed in claim 1, including supplying the fuel injection valve with the second current intensity at least once over a specific period of time during the clearing operating mode.

6. The method as claimed in claim 5, including supplying the fuel injection valve with the second current intensity repeatedly over the specific period of time.

7. The method as claimed in claim 1, including carrying out the clearing operating mode when an activation signal which is directed to activating the internal combustion engine occurs.

8. The method as claimed in claim 1, including carrying out the clearing operating mode before a fuel operating pressure is built up.

9. The method as claimed in claim 1, wherein in the clearing operating mode the fuel injection valve is supplied with a fuel pressure which corresponds to a fuel operating pressure.

10. The method as claimed in claim 1, including selecting the second current intensity to be constant during the clearing operating mode.

11. The method as claimed in claim 1, wherein a common rail injector is used as the fuel injection valve.

12. An internal combustion engine for carrying out the method as claimed in claim 1, comprising: a combustion chamber; at least one fuel injection valve for introducing fuel into the combustion chamber, the fuel injection valve being supplied with a specific current intensity using pulse width modulation in order to set a specific throughflow cross section of a fuel flow connection into the combustion chamber; and a control device designed to select the specific current intensity to be equal to a first current intensity during a normal operating mode of the internal combustion engine and equal to a second current intensity during a clearing operating mode, wherein the second specific current intensity is higher than the first specific current intensity, and wherein the specific throughflow cross section is set at a maximum during the clearing operating mode, and the specific throughflow cross section is set to less than the maximum during the normal operating mode.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The single FIGURE shows a diagram in which the current intensity which is present at a fuel injection valve of an internal combustion engine is plotted over time.

DETAILED DESCRIPTION OF THE INVENTION

(2) The single profile which is illustrated in the diagram of the FIGURE shows the profile of a current intensity of the electric current flowing through a fuel injection valve of an internal combustion engine. The fuel injection valve serves to introduce fuel into a combustion chamber of the internal combustion engine. For this purpose, it has a fuel flow connection into the combustion chamber, the throughflow cross section of which fuel flow connection is set by supplying the fuel injection valve with a specific current intensity over a specific duration. In this context, the internal combustion engine can be operated in at least two different operating modes, specifically a normal operating mode and a clearing operating mode. During the normal operating mode, the specific current intensity with which the fuel injection valve is supplied is selected to be at maximum equal to a first current intensity. In contrast, in the clearing operating mode a second current intensity, which is higher than the first current intensity, is to be used for the specific current intensity.

(3) In the clearing operating mode, the fuel injection valve is supplied at least once, but preferably repeatedly, with the second current intensity, in each case over a specific time period. In the exemplary embodiment illustrated here, the clearing operating mode is performed over a clearing operating mode time period t.sub.F. During the latter, the fuel injection valve is supplied with the second current intensity I.sub.2 during four time periods t.sub.F1, t.sub.F2, t.sub.F3 and t.sub.F4. The second current intensity which is used during each time period t.sub.F1, t.sub.F2, t.sub.F3 and t.sub.F4 corresponds, for example, to the respectively highest current intensity occurring in these time periods t.sub.F1, t.sub.F2, t.sub.F3 and t.sub.F4. The clearing operating mode time period t.sub.F4 occurs here before a time t.sub.0 at which the internal combustion engine is activated. Starting from this time t.sub.0, the normal operating mode of the internal combustion engine is carried out. This is apparent, in particular, from the fact that the supplying of the fuel injection valve with the first current intensity I.sub.1, which is lower than the second current intensity I.sub.2, follows the clearing operating time period t.sub.F.