Bistable electromagnetic actuator

Claim 2

A solenoid device comprising a case having first and second opposed end walls and side walls extending between said end walls, a permanent magnet element positioned within said case and interconnected at one end with one of said end walls, an armature extending into said case through the other of said end walls and in magnetic circuit with said other of said end walls, said armature being reciprocable axially of said armature toward and away from said magnet element in said case, coil means in said case surrounding the portion of said armature extending within said case, said coil means extending beyond said armature toward said magnet element, a pole piece interconnected with the inward end of said magnet element and extending into said coil in coaxial alignment with said armature, and a shunt member positioned to provide a magnetic flux path from said pole piece to said side walls betWeen said magnet element and said coil with a gap of low magnetic permeability in said path, said armature contacting said pole piece within said coil at the inward end of such reciprocating movement of said armature to pass substantially all of the magnetic flux generated by said coil through the area of contact between said armature and said pole piece; and said pole piece, said case, said armature and said shunt member being formed of material having high magnetic permeability.

Claim 3

A solenoid device comprising a case having first and second opposed end walls and side walls extending between said end walls; a permanent magnet element positioned within said case and interconnected at one end with one of said end walls; an armature extending into said case through the other of said end walls and in magnetic circuit with said other of said end walls, said armature being reciprocable axially of said armature toward and away from said magnet element in said case; coil means in said case surrounding the portion of said armature extending within said case; a pole piece having a first portion in contact with the inward end of said magnet element, a second portion of a lesser cross section than said first portion and extending toward said armature, and having an annular shoulder between said first and second portions; a disk of low magnetic permeability material on said shoulder; said coil means including a coil form of low magnetic permeability material which extends circumjacent said second portion of said pole piece; a shunt member contacting said case and circumscribing the portion of said coil form around said second portion and seated against said disk, whereby such portion of said coil form and said disk define a low magnetic permeability gap between said pole piece and said shunt member; said coil means including a pair of end flanges and being positioned with one of said end flanges adjacent said shunt member and the other of said end flanges adjacent to said other of said end walls; and a resilient element confined between said other end flange and said other of said end walls for retaining said coil meAns, shunt member and disk in their respective assembled positions; and said pole piece, said case, said armature and said shunt member being formed of material having high magnetic permeability.

Claim 4

A solenoid device comprising a case having first and second opposed end walls and side walls extending between said end walls; a permanent magnet element positioned within said case and interconnected at one end with one of said end walls; an armature extending into said case through the other of said end walls and in magnetic circuit with said other of said end walls, said armature being reciprocable axially of said armature toward and away from said magnet element in said case; coil means in said case surrounding the portion of said armature extending within said case; a pole piece having a first portion in contact with the inward end of said magnet element, a second portion of a lesser cross section than said first portion and extending toward said armature, and having an annular shoulder between said first and second portions; a disk of low magnetic permeability material on said shoulder; said coil means including a coil form of low magnetic permeability material which extends circumjacent said second portion of said pole piece; a shunt member contacting said case and circumscribing the portion of said coil form around said second portion and seated against said disk, whereby such portion of said coil form and said disk define a low magnetic permeability gap between said pole piece and said shunt member; said coil means including a pair of end flanges and being positioned with one of said end flanges adjacent said shunt member and the other of said end flanges adjacent to said other of said end walls; and a resilient element confined between said other end flange and said other of said end walls for retaining said coil meAns, shunt member and disk in their respective assembled positions; and said pole piece, said case, said armature and said shunt member being formed of material having high magnetic permeability.

Claim 5

A solenoid device comprising a case having side walls between two opposed ends of such case; a permanent magnet element positioned within said case adjacent one end thereof, said magnet being interconnected at one pole portion with one end of said side walls and having an opposite pole portion exposed within said case; an armature extending into said case through the other end of said case and in magnetic circuit with the respective adjacent end of said side walls, said armature being reciprocable axially of said armature toward and away from said exposed pole portion of said magnet element in said case; coil means in said case surrounding said armature; a pole piece interconnected with said exposed pole portion of said magnet element within said case and extending toward said armature in coaxial alignment with said armature; a shunt member contacting said side walls and extending closely adjacent to said pole piece to provide a magnetic flux path from said pole piece to said side walls between said magnet element and said coil, said shunt member being spaced from said pole piece to provide a gap of low magnetic permeability therebetween in said path; said armature contacting said pole piece at the inward end of such reciprocating movement of said armature to pass substantially all of the magnetic flux generated by said coil through the area of contact between said armature and said pole piece; and said pole piece, said case, said armature and said shunt member being formed of material having high magnetic permeability.

Claim 6

A solenoid device comprising a case having side walls between two opposed ends of such case; a permanent magnet element positioned within said case adjacent one end thereof, said magnet being interconnected at one pole portion with one end of said side walls and having an opposite pole portion exposed within said case; an armature extending into said case through the other end of said case and in magnetic circuit with the respective adjacent end of said side walls, said armature being reciprocable axially of said armature toward and away from said exposed pole portion of said magnet element in said case; coil means in said case surrounding said armature; a pole piece interconnected with said exposed pole portion of said magnet element within said case and extending toward said armature in coaxial alignment with said armature; a shunt member contacting said side walls and extending closely adjacent to said pole piece to provide a magnetic flux path from said pole piece to said side walls between said magnet element and said coil, said shunt member being spaced from said pole piece to provide a gap of low magnetic permeability therebetween in said path; said armature contacting said pole piece at the inward end of such reciprocating movement of said armature to pass substantially all of the magnetic flux generated by said coil through the area of contact between said armature and said pole piece; and said pole piece, said case, said armature and said shunt member being formed of material having high magnetic permeability.

Claim 7

A solenoid device as in claim 3 wherein said shunt member is an annular member having a central aperture of a cross section mating with the cross section of the adjacent portion of said pole piece, and said shunt member circumscribing said pole piece, whereby said gap is an annular gap between said pole piece and the surface of said shunt member defining said aperture.

Claim 8

Apparatus according to claim 3, including resilient means for urging said armature outwardly relative to said case.

Claim 9

Apparatus according to claim 5, including flange means secured to said armature at a location spaced outwardly from said case, and spring means surrounding said armature between said case and said flange means.

Claim 10

Apparatus according to claim 2 wherein said other of said end walls has an aperture therein, and a cylindrical sleeve disposed within said aperture and adapted to receive said armature in sliding relationship therewith, said sleeve formed of material having a high magnetic permeability.

Claim 11

Apparatus according to claim 7, including a flange projecting outwardly from said sleeve, said flange being adapted to engage the inner surface of said other of said end walls, said resilient element being confined between said flange of said sleeve and said other end flange of said coil means.

Claim 12

Apparatus according to claim 8, wherein said armature has a flange portion of enlarged cross section at said inward end, said flange portion adapted to cooperate with the inwardmost end of said sleeve to limit the movement of said armature in an outward direction.