Patent ID: 7729848

Claim:
A device for charging and discharging at least one piezo-actuator for an injection valve in an internal combustion engine, comprising: an output stage connected to said piezo-actuator for generating a load current for charging and discharging said piezo-actuator as a function of a control signal input to said output stage; an integrated circuit connected to said output stage for providing the control signal as a function of an actuation signal input to said integrated circuit, said integrated circuit including a control loop; a microcontroller connected to said integrated circuit for providing the actuation signal; and an emergency discharge circuit connected to said piezo-actuator and to said integrated circuit for discharging said piezo-actuator if at least one of said output stage and said micro-controller fails such that said piezo-actuator does not discharge, said emergency discharge circuit setting the load current which flows during discharge, having a current setting element, said control loop applying an output signal to said current setting element and comparing a load current actual value with a load current setpoint value and providing a control error signal as the output signal, and said emergency discharge circuit being activated if said control loop fails to apply the output signal to said current setting element, for emergency discharge of said piezo-actuator.