Controlled three-way proportional valve unit

A regulated proportional three-way valve unit with a valve group comprising:

• two single valves;
• an actuating device that actuates the single valves of the valve group;
• and
• a regulating unit (21) acting on the actuating device and having a control-signal input, wherein;
• the single valves of the valve group are constructed as two poppet valves (24, 25) disposed opposite one another with valve spindles (28, 29) that can move in opposite directions;
• the two valve spindles (28, 29) are biased in mutually opposite directions by means of a biasing device, specifically in such a way that a first (24) of the poppet valves is opened and the second poppet valve (25) is closed while the actuating device is inactive;
• a valve chamber (35) of the first poppet valve (24) and a valve chamber (36) of the second poppet valve (25) are in communication together with a first port (37) of the three ports of the valve unit;
• the actuating device has an actuator, which is common to both poppet valves (24, 25) and acts on both valve spindles (28, 29), and which, depending on its pressurization, changes the position of the valve spindles against the action of the biasing device;
• the actuating device and the biasing device are matched to one another in such a way that, during steady changes of the input variable fed to the actuating device from a first operating value to a second operating value in a manner offset relative to one another, the first poppet valve (24) is closed progressively over its entire operating travel at first and only then is the second poppet valve (25) opened progressively over its entire operating travel;
• and
• a sensor (43, 47) supplies a signal, which corresponds to a relative distance of the two valve spindles (28, 29) from one another and is fed back to the regulating unit (21).