Method and device for ascertaining a correction value for a fuel injection quantity

A method for ascertaining a correction value for a fuel metering of a fuel injector of an internal combustion engine, in which fuel is injected from a high pressure accumulator into a combustion chamber with the aid of the fuel injector, the method comprising:

• ascertaining a representative value that is representative for a static flow rate through the fuel injector, by ascertaining, during at least one injection process of the fuel injector, a ratio of a pressure difference occurring in the high pressure accumulator as a result of the injection process and an associated duration which is characteristic for the injection process, wherein the representative value is ascertained from a mean value of ratios of pressure difference and associated duration ascertained in multiple injection processes of the fuel injector;
• and
• ascertaining the correction value based on a comparison of the representative value and a comparative value.

A method for ascertaining a correction value for a fuel metering of a fuel injector of an internal combustion engine, in which fuel is injected from a high pressure accumulator into a combustion chamber with the aid of the fuel injector, the method comprising:

• ascertaining a representative value that is representative for a static flow rate through the fuel injector, by ascertaining, during at least one injection process of the fuel injector, a ratio of a pressure difference occurring in the high pressure accumulator as a result of the injection process and an associated duration which is characteristic for the injection process;
• and
• ascertaining the correction value based on a ratio of the representative value and a mean value of corresponding representative values of all fuel injectors of the internal combustion engine.

A processing unit comprising a processor, wherein the processor is configured to:

• for each of a plurality of fuel injectors, ascertain a respective representative value that is representative of a respective flow rate through the respective fuel injector, by ascertaining, during at least one respective injection process of the respective fuel injector, a ratio of (a) a pressure difference occurring in the high pressure accumulator as a result of the at least one respective injection process and (b) a respective duration associated with the at least one respective injection process;
• and
• based on a relationship between (a) the respective representative value ascertained for a particular one of the plurality of fuel injectors and (b) the respective representative values ascertained for the others of the plurality of fuel injectors, ascertain, for the particular one of the plurality of fuel injectors, a respective correction value for correcting a respective fuel metering of the particular one of the plurality of fuel injectors so that the respective fuel metering of the particular one of the plurality of fuel injectors differs from fuel metering of others of the plurality of fuel injectors.

A non-transitory machine-readable memory medium, on which is stored a computer program that is executable by a processor and that, when executed by the processor, causes the processor to perform a method, the method comprising:

• for each of a plurality of fuel injectors, ascertaining a respective representative value that is representative of a respective flow rate through the respective fuel injector, by ascertaining, during at least one respective injection process of the respective fuel injector, a ratio of (a) a pressure difference occurring in the high pressure accumulator as a result of the at least one respective injection process and (b) a respective duration associated with the at least one respective injection process;
• and
• based on a relationship between (a) the respective representative value ascertained for a particular one of the plurality of fuel injectors and (b) the respective representative values ascertained for the others of the plurality of fuel injectors, ascertaining, for the particular one of the plurality of fuel injectors, a respective correction value for correcting a respective fuel metering of the particular one of the plurality of fuel injectors so that the respective fuel metering of the particular one of the plurality of fuel injectors differs from fuel metering of others of the plurality of fuel injectors.