초록 ▼

A servo valve has a miniature force motor embedded in a main fluid chamber to directly operate between two nozzles to generate a differential pressure in two ports. The miniature force motor includes two disc ring-shaped magnets in opposing magnetic orientation, an armature base and poppet ends of m

A servo valve has a miniature force motor embedded in a main fluid chamber to directly operate between two nozzles to generate a differential pressure in two ports. The miniature force motor includes two disc ring-shaped magnets in opposing magnetic orientation, an armature base and poppet ends of magnetic material coupled to an armature shaft having pilot ends that interface to form the pilot stage valves at each armature shaft end. The armature shaft extends through a center hole in the magnets, armature base, and the poppet ends and engages bearing elements at each end allowing lateral armature motion. Two elastic members provide restoring forces to the armature assembly. Guide/stops have shaped magnetic surfaces to control the magnetic path and to linearize the force versus stroke and to increase the proportional stroke of the armature.

대표청구항 ▼

What is claimed is: 1. A servo valve, comprising: a chamber having first and second end caps with first and second pilot valve seats with openings to first and second ports; a force motor comprising a stator having a stator coil and forming a cylindrical portion of said chamber, wherein said force

What is claimed is: 1. A servo valve, comprising: a chamber having first and second end caps with first and second pilot valve seats with openings to first and second ports; a force motor comprising a stator having a stator coil and forming a cylindrical portion of said chamber, wherein said force motor further comprises: an armature assembly moveable inside said chamber in response to a current in said stator coil, wherein said armature assembly is held on either end of said chamber with elastic members, wherein said armature assembly comprises: a plurality of pilot valves formed by interfacing with said chamber, wherein each of said plurality of pilot valves is formed when a pilot interfaces with one of said first and second pilot valve seats; a plurality of guide/stops in contact with said armature assembly, wherein said plurality of guide/stops forms a portion of said stator of said force motor; an armature base, and a plurality of magnets attached to said armature base, wherein said plurality of magnets are magnetically polarized axially in opposing directions; a third port coupled to said chamber and configured to receive fluid under pressure; and surface features located on said armature base and on one of said plurality of guide/stops, wherein said surface features are sloped to modify a magnetic path of first and second air gaps and leakage paths between said one of said plurality of guide/stops and said armature base whereby the linearity of a magnetic force to an applied input current can be adjusted by adjusting said surface features, wherein a surface feature of at least one of said plurality of guide/stops comprises: a stepped surface configured to approximate a concave shape, wherein the length of the concave shape can be adjusted to lengthen the proportional stroke and the linearity of said proportional stroke can be adjusted by the degree the stepped surface approximates the concave shape, said at least one of said plurality of guide/stops further comprises a corresponding surface radially oppositely spaced apart from said stepped surface and having a slope matching said stepped surface. 2. The servo valve as recited in claim 1, wherein said servo valve further comprises: poppet ends of magnetic material coupled axially with said plurality of magnets, wherein said armature assembly slides on bearing contact surfaces of said plurality of poppet ends and said armature base. 3. The servo valve as recited in claim 1, wherein one of said surface features is a slope feature that affects a magnetic flux leakage path between said one of said plurality of guide/stops and said armature base. 4. The servo valve as recited in claim 1, wherein said first air gap is formed between a first end of said armature base and a first of said plurality of guide/stops, wherein said second air gap is formed between a second end of said armature base and a second of said plurality of guide/stops, wherein said first and said second air gaps vary in direct, inverse relationship with one another as said armature assembly moves laterally inside said chamber. 5. The servo valve as recited in claim 4, wherein fluid flow to said first and second ports is controlled by a position of said armature assembly, wherein said position of said armature assembly is controlled by a magnitude and direction of said current in said stator coil. 6. The servo valve as recited in claim 1 further comprises: said stator coil circumferentially wound in a bobbin assembly surrounding said chamber, wherein when said stator coil is energized it produces a magnetic flux that interacts with a magnetic flux of said plurality of magnets to produce a lateral force. 7. The servo valve as recited in claim 6, wherein said magnetic flux produced by said stator coil aids or reduces said magnetic flux produced by one of said plurality of magnets and aids said magnetic flux produced by another one of said plurality of magnets based on a direction of said current in said stator coil. 8. The servo valve as recited in claim 1, wherein a first of said plurality of pilot valves increasingly opens and a second of said plurality of pilot valves increasingly closes thereby changing pressure drops in said first and second ports as said armature assembly moves inside said chamber. 9. The servo valve as recited in claim 1, wherein a layer of polytetraflouroethylene is deposited on a surface of said armature assembly to function as a bearing. 10. A servo valve, comprising: a chamber having first and second end caps with first and second pilot valve seats with openings to first and second ports; a force motor comprising a stator having a stator coil and forming a cylindrical portion of said chamber, wherein said force motor further comprises: an armature assembly moveable inside said chamber in response to a current in said stator coil, wherein said armature assembly is held on either end of said chamber with elastic members, wherein said armature assembly comprises: a plurality of pilot valves formed by interfacing with said chamber, wherein each of said plurality of pilot valves is formed when a pilot interfaces with one of said first and second pilot valve seats; an armature base; and a plurality of magnets attached to said armature base, wherein said plurality of magnets are magnetically polarized axially in opposing directions; a plurality of guide/stops in contact with said armature assembly, wherein said plurality of guide/stops forms a portion of said stator of said force motor; wherein said plurality of guide/stops contacts a poppet end on said armature assembly using circumferential bearing elements; a third port coupled to said chamber and configured to receive fluid under pressure; and surface features located on said armature base and on one of said plurality of guide/stops, wherein said surface features are sloped to modify a magnetic path of first and second air gaps and leakage paths between said one of said plurality of guide/stops and said armature base, whereby the linearity of a magnetic force to an applied input current can be adjusted by adjusting said surface features, wherein a surface feature of at least one of said plurality of guide/stops comprises: a stepped surface configured to approximate a concave shape, wherein the length of the concave shape can be adjusted to lengthen the proportional stroke and the linearity of said proportional stroke can be adjusted by the degree the stepped surface approximates the concave shape, said at least one of said plurality of guide/stops further comprises a corresponding surface radially oppositely spaced apart from said stepped surface and having a slope matching said stepped surface. 11. The servo valve as recited in claim 10, wherein said circumferential bearing elements are made of a high density polyethylene. 12. The servo valve as recited in claim 10, wherein said circumferential bearing elements are used as a frictional contact surface. 13. The servo valve as recited in claim 10, wherein an air gap results from forcing said armature assembly to contact said plurality of guide/stops using said circumferential bearing elements, wherein said air gap is sized to ensure that there is no additional contact between said plurality of guide/stops and said armature base when said armature assembly moves in a non-lateral direction under an influence of external vibration forces. 14. The servo valve as recited in claim 10, wherein one of said surface features is a slope feature that affects a magnetic flux leakage path between said one of said plurality of guide/stops and said armature base. 15. The servo valve as recited in claim 10 further comprises: said stator coil circumferentially wound in a bobbin assembly surrounding said chamber, wherein when said stator coil is energized it produces a magnetic flux that interacts with a magnetic flux of said plurality of magnets to produce a lateral force. 16. The servo valve as recited in claim 15, wherein said magnetic flux produced by said stator coil aids or reduces said magnetic flux produced by one of said plurality of magnets and aids said magnetic flux produced by another one of said plurality of magnets based on a direction of said current in said stator coil. 17. A servo valve, comprising: a chamber having first and second end caps with first and second pilot valve seats with openings to first and second ports; a force motor comprising a stator having a stator coil and forming a cylindrical portion of said chamber, wherein said force motor further comprises: an armature assembly moveable inside said chamber in response to a current in said stator coil, wherein said armature assembly is held on either end of said chamber with elastic members, wherein said armature assembly comprises: a plurality of pilot valves formed by interfacing with said chamber, wherein each of said plurality of pilot valves is formed when a pilot interfaces with one of said first and second pilot valve seats; an armature base; and a plurality of magnets attached to said armature base, wherein said plurality of magnets are magnetically polarized axially in opposing directions; a non-magnetic shaft configured to engage a cylindrical bearing element, wherein said non-magnetic shaft is coupled to said elastic members that operate to center said armature assembly between said first and second pilot valve seats; and a plurality of guide/stops in contact with said armature assembly, wherein said plurality of guide/stops forms a portion of said stator of said force motor; a third port coupled to said chamber and configured to receive fluid under pressure; and surface features located on said armature base and on one of said plurality of guide/stops, wherein said surface features are sloped to modify a magnetic path of first and second air gaps and leakage paths between said one of said plurality of guide/stops and said armature base, whereby the linearity of a magnetic force to an applied input current can be adjusted by adjusting said surface features, wherein a surface feature of at least one of said plurality of guide/stops comprises: a stepped surface configured to approximate a concave shape, wherein the length of the concave shape can be adjusted to lengthen the proportional stroke and the linearity of said proportional stroke can be adjusted by the degree the stepped surface approximates the concave shape, said at least one of said plurality of guide/stops further comprises a corresponding surface radially oppositely spaced apart from said stepped surface and having a slope matching said stepped surface. 18. The servo valve as recited in claim 17, wherein said cylindrical bearing element engages said non-magnetic shaft at bearing surfaces. 19. The servo valve as recited in claim 17, wherein each pilot end of said non-magnetic shaft is operable to interface with one of said first and second pilot valve seats as said armature assembly moves laterally left and right. 20. The servo valve as recited in claim 17, wherein said cylindrical bearing element is ported so that fluid is delivered to a volume between a pilot end of said non-magnetic shaft and one of said first and second pilot valve seats. 21. The servo valve as recited in claim 17, wherein one of said surface features is a slope feature that affects a magnetic flux leakage path between said one of said plurality of guide/stops and said armature base. 22. The servo valve as recited in claim 17, wherein the sloped stepped surface configured to approximate a desired concave face has a recess toward the centrifugal direction from said shaft and such stepped surface further comprises a plurality of cylindrical surfaces with gradually decreasing diameters toward the armature assembly. 23. The servo valve as recited in claim 17 further comprises: said stator coil circumferentially wound in a bobbin assembly surrounding said chamber, wherein when said stator coil is energized it produces a magnetic flux that interacts with a magnetic flux of said plurality of magnets to produce a lateral force. 24. The servo valve as recited in claim 23, wherein said magnetic flux produced by said stator coil aids or reduces said magnetic flux produced by one of said plurality of magnets and aids said magnetic flux produced by another one of said plurality of magnets based on a direction of said current in said stator coil. 25. The servo valve as recited in claim 17, wherein said non-magnetic shaft is spatially stiffened via compression springs attached to said non-magnetic shaft. 26. The servo valve as recited in claim 25, wherein said non-magnetic shaft is displaced by a magnetic flux compressing said compression springs while said non-magnetic shaft maintains, contact with the bearing surfaces.