Patent ID: 9450521
Filing Date: 2016-09-20
CPC Classification: F02D,H01L,H02N

Claim Text:
1. A method for driving a piezoelectric actuator for a fuel injector in a combustion engine, the piezoelectric actuator having a piezo stack having a setpoint length, the piezo stack, polarized during its production by a polarization process initially at a first field strength, the method comprising: driving the piezo stack during a regular operation of the combustion engine at a second field strength that is smaller than the first field strength; monitoring a change in length of the piezo stack from the setpoint length of the piezo stack, the change in length being caused by depolarization during regular operation of the combustion engine; and in response to reaching a prespecified threshold value for the change in length of the piezo stack, operating said piezo stack at a third field strength until the setpoint length of the piezo stack is reached.