US Patent 9151354 Valve device

A valve device for electrically regulating a pressure in a hydraulic fluid flow through the valve device in response to an actuating force during a normal operation and mechanically regulating said pressure during a fail-safe operation when no actuating force is present is disclosed. The valve device has a valve chamber. A first valve member is movable within the valve chamber in an axial direction to interact with a first valve seat in response to the actuating force in order to restrict the hydraulic fluid flow into the valve chamber during normal operation. The first valve member is spring-loaded away from the second seat in a direction opposite that of the actuating force such that the first valve member is movable in the axial direction. A second valve member forms a movable chamber wall portion defining a part of the valve chamber. The second valve member is spring-loaded in the direction of the actuating force. The second valve member has a through hole for allowing hydraulic fluid flow out of the valve chamber during normal operation. The spring-loaded first valve member is arranged to close the flow passage during fail-safe operation such that the pressure is mechanically regulated by the second valve member acting on the second valve seat.