Method for operating injectors of an injection system

Abstract

The present disclosure provides a method for operating injectors of an injection system, which has a pressure accumulator (rail), of an internal combustion engine, in which needle movement of the injectors is controlled directly by way of an actuator. The method may comprise: determining an actual injection quantity of each injector of the injection system via a fuel quantity which is requested at a pump of the injection system for each injector for a predefined time period or via a pressure loss in the pressure accumulator, the pressure loss brought about by way of the injection operation; comparing the determined actual fuel quantity with a setpoint fuel quantity; and if a deviation is determined in an injector, carrying out an open/closed loop control method for reducing/eliminating the determined deviation.

Claims

1. A method for operating injectors of an injection system including a pressure accumulator, of an internal combustion engine, the method comprising: directly controlling needle movement of the injectors with respective actuators; correcting a deviation in at least one of an opening time or a closing time of one of the injectors using a closing time regulation of the one of the injectors by comparing the opening time or the closing time with a corresponding setpoint value; determining an actual injection quantity of each injector of the injection system via a fuel quantity which is requested at a pump of the injection system for each injector for a predefined time period or via a pressure loss in the pressure accumulator, the pressure loss brought about by way of individual injections; comparing the determined actual fuel quantity with a setpoint fuel quantity; and if a remaining deviation is determined in an injector, carrying out a correction by adapting an actuation duration or an energization of the actuator to reduce the determined deviation.

2. A method for operating an internal combustion engine comprising injectors and, a pressure accumulator, the method comprising: directly controlling needle movement of the injectors with respective actuators; correcting a deviation in at least one of an opening time or a closing time of a particular injector by regulating the closing time based on a comparison of the opening time or the closing time with a corresponding setpoint value; determining an actual injection quantity of each injector of the injection system via a fuel quantity requested at the pump of the injection system for each injector for a predefined time period or via the pressure loss in the pressure accumulator brought about by individual injection operations; calculating a mean value or a median value based on the determined actual injection quantities; comparing the determined actual injection quantity among the injectors of the injection system, including comparing all deviations of individual injection quantities from the mean value or the median value; and if a remaining deviation is determined in an injector, carrying out a correction by adapting an actuation duration or an energization of the actuator to recalibrate the particular injector.

3. The method as claimed in claim 1, further comprising determining whether a magnitude of a particular deviation exceeds a correctable maximum value.

4. The method as claimed in claim 1, wherein the method is carried out as an on-board diagnosis during normal operation of the internal combustion engine.

5. A method for operating injectors of an injection system including a pressure accumulator, of an internal combustion engine, the method comprising: directly controlling needle movement of the injectors with respective actuators; correcting a deviation in the closing time of an injector via regulating the closing time of the respective injector, and correcting any remaining deviation by: determining an actual injection quantity of each injector of the injection system via a fuel quantity which is requested at a pump of the injection system for each injector for a predefined time period or via a pressure loss in the pressure accumulator, the pressure loss brought about by way of individual injections; comparing the determined actual fuel quantity with a setpoint fuel quantity; and if a deviation is determined in an injector, carrying out an open or a closed loop control method to reduce the determined deviation.

6. The method as claimed in claim 2, further comprising determining whether a magnitude of a particular deviation exceeds a correctable maximum value.

7. The method as claimed in claim 2, wherein the method is carried out as an on-board diagnosis during normal operation of the internal combustion engine.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be explained in detail in the following text using exemplary embodiments in conjunction with the drawing, in which:

(2) FIG. 1 shows a flow chart of a first embodiment of a method for operating injectors,

(3) FIG. 2 shows a flow chart of a second embodiment of a method of this type, and

(4) FIG. 3 shows a flow chart of a third embodiment of a method of this type.

DETAILED DESCRIPTION

(5) The method described here for operating injectors of an injection system, which has a pressure accumulator (rail), of an internal combustion engine is a method which is carried out as an on-board diagnosis during the normal operation of the injection system. The injectors of said injection system are those, the needle movement of which is controlled directly by way of an actuator, that is to say those which operate without a servovalve. The internal combustion engine may be a diesel engine.

(6) In step 1 of the method which can also be called a calibrating method of the injectors, the actual injection quantity of each injector of the injection system is determined via the fuel quantity which is requested at the pump of the injection system for each injector for a predefined time or via the pressure loss in the pressure accumulator (rail), which pressure loss is brought about by way of the injection operation. In steps 2 and 3, setpoint values are provided for the fuel quantity which is requested at the pump or the pressure loss in the pressure accumulator, which setpoint values are stored, for example, in the control device of the internal combustion engine. In step 4, the determined requested fuel quantity or the determined pressure loss is compared with the setpoint fuel quantity or the setpoint pressure loss for each injector. If a deviation in an injector is determined, an open/closed loop control method is carried out in step 5, in order to reduce or to eliminate the determined deviation and in this way to carry out a correction of the injection quantity which is injected by the corresponding injector, for example a closing time regulation.

(7) In the example method variant shown in FIG. 2, the actual injection quantity of each injector is likewise determined via the fuel quantity which is requested at the pump of the injection system for each injector for a predefined time or via the pressure loss in the pressure accumulator, which pressure loss is brought about by way of the injection operation (step 6). The diesel engine which is addressed here has four cylinders and therefore also four injectors, the actual injection quantities being determined for all four injectors. A mean value is formed from the obtained values in step 7, and a calibration of the determined requested fuel quantity or the determined pressure loss among the four injectors of the injection system takes place in step 8. If a deviation from the mean value is determined in an injector, a corresponding open/closed loop control method is carried out for reducing/eliminating the determined deviation (step 9).

(8) In the example method variant which is shown in FIG. 3, a deviation in the opening and/or closing time of an injector of the injection system is corrected via another method (step 20). The remaining deviation which was not able to be corrected by way of the other method is then determined and corrected by way of the method according to the invention. Here, in step 21, in the above-described way, the actual injection quantity of each injector of the injection system is determined via the fuel quantity requested at the pump of the injection system for each injector for a predefined time or via the pressure loss in the pressure accumulator, which pressure loss is brought about by way of the injection operation. In steps 22 and 23, a setpoint fuel quantity or a setpoint pressure loss is made available for each injector from the control device. The determined requested fuel quantity or the determined pressure loss are compared with the setpoint fuel quantity or the setpoint pressure loss in step 24. If a deviation in an injector is determined, a corresponding open/closed loop control method is carried out in step 25. In this way, the remaining deviation (type 2) can be corrected. The open/closed loop control method which is applied can comprise an adaptation of the actuation duration of the injector as additional correction or a correction by way of adaptation of the actuator energization.