Rotary servovalve and control system

A rotary servovalve system comprising

• a pressurized fluid supply having a pressure supply line leading therefrom,
• a fluid reservoir having a fluid relief line leading thereto,
• a valve housing having a valve cavity of circular cross section defined therewithin and defining at least one rectangular input port to said valve cavity coupled to said pressure supply line, at least one rectangular outlet port from said valve cavity coupled to said relief line and located diametrically opposite said inlet port, and at least one first rectangular fluid control port and at least one second rectangular fluid control port in communication with said valve cavity and said first and second control ports are located diametrically opposite each other and equidistant from said inlet and outlet ports,
• a bidirectional valve closure element having a gate portion with at least one pair of mutually parallel, longitudinally oriented and longitudinally aligned flow directing faces of rectangular shape and said valve closure element is located within said valve cavity and is coaxially aligned and rotatable therewithin to, in the alternative:
• (1) create concurrent flow paths between said first fluid control port and said inlet port and between said second fluid control port and said outlet port, (2) block all of said ports, and (3) create concurrent flow paths between said second fluid control port and said inlet port and between said first fluid control port and said outlet port, and
• a rotary solenoid having a stator and an armature with at least one permanent magnet rotatable within said stator between two extreme positions and biased toward a null position midway between said two extreme positions by magnetic force from said permanent magnet, and said armature is joined to said valve closure element so that when said armature is at said null position said valve closure element blocks all of said ports as aforesaid,
• a position sensor located proximate to said rotary solenoid to provide a feedback signal indicative of the position and direction of rotation of said armature relative to said null position, and
• a control circuit responsive to said position sensor to provide a feedback electrical signal having an electrical frequency response bandwidth of at least about one hundred twenty hertz to said stator to move said valve closure element to a target orientation relative to said valve housing.

In a rotary servovalve system in which fluid is directed through at least one inlet port, at least one outlet port, at least one first fluid control port, and at least one second fluid control port in a valve housing as directed by a movable valve gate element rotatable within said housing in opposite directions of angular rotation from a position prohibiting fluid flow through any of said ports to alternative positions permitting fluid flow in alternative opposite directions through each of said first and second fluid control ports, the improvement comprising:

• a rotary magnetic solenoid having an armature that includes at least one permanent magnet and which is rotatable relative to a stator formed as an electromagnet that is energizable to alternatively create electromagnetic fields having opposite polarities from each other and which, when deenergized, allows said armature to return to a neutral null position from positions of orientation in opposite angular directions, and said armature is coupled to carry said movable valve gate element in angular rotation therewith,
• a position sensor located proximate to said rotary magnetic solenoid and which senses the position of said solenoid armature relative to said stator and provides a feedback signal responsive thereto, and
• a control circuit coupled between said position sensor and said rotary magnetic solenoid to provide control inputs having an electrical frequency response bandwidth of at least about one hundred twenty hertz to said stator of said rotary magnetic solenoid.