Servo positioning system

A method of positioning a valve member relative to a passage having an inlet and an outlet to vary fluid flow through said passage by varying the size of said outlet, wherein said valve member is connected to a spring biased armature movable axially along an axis within a housing, one end of said armature forming a first gap with said housing, the other end of said armature forming a second gap with said housing, means adjacent each gap for measuring the flux density across each gap and producing output signals corresponding to each flux density, means for sensing said output signals to produce a sensed position signal representative of the location of said armature in said housing, a permanent magnet disposed about said armature, coil means disposed about said armature responsive to an energizing current for controlling said movement of said armature against its spring bias within said housing, the method comprising:

• a. Introducing a command signal to energize said coil means to locate said armature at a desired position in said housing and to position said valve member relative to said passage;
• and
• b. Maintaining said command signal while increasing the fluid pressure drop across said passage inlet and outlet to thereby cause said armature to shift from said desired position to a second desired position represented by said sensed position signal relocating said valve member relative to said passage to reduce the size of said passage outlet.

A servo device comprising:

• a work member;
• an armature connected to said member being rectilinearly movable within a housing along an axis to so move said member, means normally biasing said armature in one direction within said housing, one end of said armature forming a first gap with said housing, and another end of said armature forming a second gap with said housing, said gaps varying in direct, inverse relationship with one another as said armature moves along said axis;
• a permanent magnet means secured to said housing and disposed about said armature for producing a clockwise flux path through one of said gaps and a counter flux path through the other of said gaps to position said armature along said axis;
• coil means secured to said housing and disposed about said armature responsive to an energizing current for controlling said movement of the armature against said biasing means;
• measurement means disposed adjacent one of said first gap and said second gap for measuring a first flux density across said one gap, said measurement means producing a first output signal corresponding to said first flux density;
• and
• means for sensing said first output signal which represents the position of said armature in said housing and the position of said connected member.

A valve comprising:

• a housing having a passage to accommodate fluid flow therethrough;
• a member in said housing movable relative to said passage to vary said flow through said passage;
• an armature connected to said member being rectilinearly movable within the housing along an axis to so move said member, means normally biasing said armature in one direction within said housing, one end of said armature forming a first gap with said housing, another end of said armature forming a second gap with said housing, said gaps varying in direct, inverse relationship with one another as said armature moves along said axis;
• a permanent magnet means secured to said housing and disposed about said armature for producing a clockwise flux path through one of said gaps and a counter-clockwise flux path through the other of said gaps to position said armature along said axis;
• coil means secured to said housing and disposed about said armature responsive to an energizing current for controlling said movement of the armature against said biasing means;
• measurement means disposed adjacent one of said first gap and said second gap for measuring a first flux density across said one gap, said measurement means producing a first output signal corresponding to said first flux density;
• means for sensing said first output signal which represents the position of said armature in said housing and the position of said connected valve member relative to said passage.