Patent ID: 6333585
Filing Date: 2001-12-25
Classification: F02D,H02N

Abstract:
Discharge circuit for a capacitive actuator (P), especially for a piezoelectrically operated injection valve for an internal combustion engine, said actuator (P) having a first terminal and a second terminal, said first terminal being connected to ground and said second terminal being connected to a voltage supply (IC) for charging the actuator (P) electrically for an actuation, comprising:a controlled discharge switch (M) having a first terminal and a second terminal, said first terminal of said discharge switch (M) being connected to said first terminal of said actuator (P), said second terminal of said discharge switch (M) being connected to said second terminal of said actuator (P), said discharge switch (M) having a controlling input being connected to a control unit which holds the discharge switch (M) open in normal operation regardless of the charge of the actuator (P) and thus prevents a discharge, said controlling input being additionally connected to the second terminal of said actuator (P) so that, in case of a failure of the control unit and a charged actuator (P), the discharge switch (M) is rendered conductive by the electric voltage of the actuator (P) and the actuator (P) is thereby discharged.