Abstract: A safety valve is provided with an electronic control unit for generating a control voltage. An electro-fluidic preliminary stage has a piezo bending actuator which can be actuated between a working position and a safety position by the control voltage and influences the flow of a secondary control fluid flow depending on its position. A fluid-mechanical main stage has an influencing device for influencing the flow of a primary working fluid flow. The influencing device can be actuated by means of the secondary control fluid flow which flows into a control chamber of the main stage. The control unit caries out a test of the preliminary stage repeatedly in an iterative manner after the expiration of a specified time interval. As part of the functionality test, the position of the piezo bending actuator is changed slightly by varying the control voltage.

Abstract: A proportional valve is provided wherein the valve has an actuating element, a compressed-air connection, a working connection, and an air-removal connection. The valve also has three valve elements arranged one after the other and each can be moved in an axial direction. A first valve element is actuated by the actuating element, a second valve element is actuated by the first valve element, and a third valve element is actuated by the second valve element. In a base position, the valve elements are spaced apart, and, within the valve, a first sealing seat effective between the first valve element and the second valve element and a second sealing seat effective between the third valve element and the housing are arranged such that by varying the position of the first valve element, different switching states can be set.

Abstract: A proportional valve is provided having a pilot control valve that can be controlled by means of a control signal and having a booster valve that can be actuated by means of the pilot control valve. The proportional valve has a compressed-air connection for connecting a compressed-air supply, a working connection, and an air-removal connection. The booster valve has three valve elements, which are arranged one after the other and can each be moved in an axial direction against a spring force.