Patent ID: 7620522

Claim:
A diagnostic device for at least one pneumatic valve actuator arrangement, comprising: a pressure sensor; a volumetric flow sensor; a control means for producing control signals for the at least one valve actuator arrangement; position sensors for detecting the position of at least one moving actuator member; a first diagnostic module for leak detection; a second diagnostic module for the detection of a choking effect in pneumatic supply and venting lines; at least one third diagnostic module for the detection of changes in load or changes in dynamic friction or for the detection of valve switching faults, the changes in dynamic friction being in response to movement of the actuator member; switching means being provided for deactivating the at least one third diagnostic module in the case of the detection of a fault by the first or second diagnostic module; and a fourth diagnostic module being provided for the detection of valve switching faults, which in the case of detection of a fault by the third diagnostic module is deactivated.