Patent ID: 7930090

Claim:
A method for adapting a valve characteristic of a fuel injection valve, which has a piezoelectrically driven nozzle needle and through which fuel is injected directly into the combustion chamber of an internal combustion engine, comprising the steps of: storing a characteristic curve between activation energy for the fuel injection valve and needle stroke for the fuel injection valve; implementing a particular needle stroke and a particular injection time for the fuel injection valve and determining a resulting first torque; determining an adjusted needle stroke and an adjusted injection time calculated to provide the same torque as the first torque at a same operating point; implementing the adjusted needle stroke and the adjusted injection time and determining a resulting second torque; comparing the second torque to the first torque; and in response to determining that the second torque is not equal to the first torque, automatically adjusting the characteristic curve by adjusting a slope of a line relating the activation energy for the fuel injection valve and the needle stroke for the fuel injection valve.