Self-latching solenoid actuator

Claim 2

A solenoid actuator having a stationary member and a moving member adapted for motion between first and second orientations with respect to said stationary member, a solenoid coil having first and second leads, a permanent magnet, and a switch, said stationary member and said moving member forming a magnetic circuit with said permanent magnet in said circuit, said solenoid coil being disposed with respect to said magnetic circuit so as to cause a magnetizing force in said circuit in response to a current therethrough, said stationary member and said moving member being adapted to magnetically urge said moving member toward said first orientation with respect to said stationary member in response to the establishment of a magnetic field in said magnetic circuit, said switch being electrically coupled to said first solenoid coil lead and adapted to switch electrical coupling with said first solenoid coil lead between first and second actuator leads in response to motion between said stationary member and said moving member.

Claim 3

The solenoid actuator of claim 1 wherein said switch has mechanical hysteresis so that said switch will not switch electrical coupling with said first solenoid lead between said first and second actuator leads until said solenoid plunger is at least approaching the end of its travel between said first and second orientations.

Claim 4

The solenoid actuator of claim 1 wherein said switch exhibits a time lag between said motion between said stationary member and said moving member, and its switching of said first solenoid coil lead between first and second actuator leads.

Claim 5

The solenoid actuator of claim 1 further comprising a return spring, said return spring being disposed between said stationary member and said moving member so as to yieldably urge said moving member from said first orientation to said second orientation with respect to said stationary member.

Claim 6

The solenoid actuator of claim 2 further comprised of a source of direct current having first and second terminals, a current limiting means and a remote switching means schematically representable as a single pole, double-throw switch having a moving contact switchable between first and second fixed contacts, said second solenoid coil lead being coupled to said moving contact of said remote switch, said first and second actuator leads being coupled to first and second terminals of said source of direct current, respectively, said first fixed contact of said remote switch being coupled to said first terminal of said source of direct current and said second fixed contact of said remote switch being coupled through said current limiting means, to said second terminal of said source of direct current.

Claim 7

A solenoid actuator comprising a stationary member, a plunger, a pErmanent magnet, a solenoid coil and a switch means, said plunger and said stationary member forming a magnetic circuit having a minimum air gap when said plunger is in the actuated position and a maximum air gap when in the fully extended position, said permanent magnet being disposed so as to form a portion of said magnetic circuit and to be subject to magnetizing forces in said magnetic circuit, said solenoid coil being disposed so as to cause a magnetizing force on said magnetic circuit 99 when current is passed through said coil, said switch means having first and second terminals and being cooperatively disposed with respect to said plunger and electrically coupled to a first end of said solenoid coil so as to be operative to switch the coupling of said first end of said solenoid coil from said first terminal to said second terminal as said plunger moves toward said actuated position and from said second terminal to said first terminal as said plunger moves toward said fully extended position.

Claim 8

A solenoid actuator comprising a stationary member, a plunger, a pErmanent magnet, a solenoid coil and a switch means, said plunger and said stationary member forming a magnetic circuit having a minimum air gap when said plunger is in the actuated position and a maximum air gap when in the fully extended position, said permanent magnet being disposed so as to form a portion of said magnetic circuit and to be subject to magnetizing forces in said magnetic circuit, said solenoid coil being disposed so as to cause a magnetizing force on said magnetic circuit 99 when current is passed through said coil, said switch means having first and second terminals and being cooperatively disposed with respect to said plunger and electrically coupled to a first end of said solenoid coil so as to be operative to switch the coupling of said first end of said solenoid coil from said first terminal to said second terminal as said plunger moves toward said actuated position and from said second terminal to said first terminal as said plunger moves toward said fully extended position.

Claim 9

The solenoid actuator of claim 6 further comprising a return spring, said return spring being disposed between said plunger and said stationary member and being operative to return said plunger to the fully extended position when the magnetic field in said magnetic circuit is substantially less than the magnetic field required to saturate said magnetic circuit.

Claim 10

The solenoid actuator of claim 6 wherein said switch means comprises first and second fixed contacts connected to said first and second terminals and a moving contact connected to said first end of said solenoid coil moveable between said first and second fixed contacts.

Claim 11

A solenoid actuator comprising: a generally cylindrical housing; a magnetic plunger within said housing having an upwardly disposed plunger face defined by a first outer diameter and an inner diameter and adapted for vertical motion between an extended position and an actuated position; a plunger rod of a second diameter substantially less than said first outer diameter connected to said plunger and extending through a clearance hole in the bottom of said housing; a cylindrical magnetic member disposed around said plunger, having a loose fit with said first outer diamter, and extending upward therefrom; a solenoid coil having first and second leads, located within and concentric to said upward extending portion of said magnetic member; a magnetic pole piece, having a clearance hole concentric therewith, disposed within said solenoid coil and spaced above the upper end of said plunger when said plunger is in said extended position; a permanent magnet having a clearance hole concentric therewith disposed within said solenoid coil and immediately above said pole piece; a magnetic top plate having a clearance hole concentric therewith disposed immediately above said solenoid coil and said permanent magnet, and extending radially outward to a position adjacent said upward extending portion of said cylindrical magnetic member; a switch actuating pin disposed within said clearance holes in said pole piece, said magnet and said top plate, and having an enlarged head extending into said inner diameter of said plunger; a coil spring disposed between said pole piece and said enlarged head on said actuating pin and yieldably urging said actuating pin and said plunger toward said extended position; and a single-pole, double-throw switch mounted above said top plate and adapted for actuation by said actuating pin, said switch being connected to said first solenoid coil lead and adapted to switch electrical coupling with said first solenoid coil lead between first and second actuator leads in response to motion of said plunger.

Claim 12

A solenoid actuator comprising: a generally cylindrical housing; a magnetic plunger within said housing having an upwardly disposed plunger face defined by a first outer diameter and an inner diameter and adapted for vertical motion between an extended position and an actuated position; a plunger rod of a second diameter substantially less than said first outer diameter connected to said plunger and extending through a clearance hole in the bottom of said housing; a cylindrical magnetic member disposed around said plunger, having a loose fit with said first outer diamter, and extending upward therefrom; a solenoid coil having first and second leads, located within and concentric to said upward extending portion of said magnetic member; a magnetic pole piece, having a clearance hole concentric therewith, disposed within said solenoid coil and spaced above the upper end of said plunger when said plunger is in said extended position; a permanent magnet having a clearance hole concentric therewith disposed within said solenoid coil and immediately above said pole piece; a magnetic top plate having a clearance hole concentric therewith disposed immediately above said solenoid coil and said permanent magnet, and extending radially outward to a position adjacent said upward extending portion of said cylindrical magnetic member; a switch actuating pin disposed within said clearance holes in said pole piece, said magnet and said top plate, and having an enlarged head extending into said inner diameter of said plunger; a coil spring disposed between said pole piece and said enlarged head on said actuating pin and yieldably urging said actuating pin and said plunger toward said extended position; and a single-pole, double-throw switch mounted above said top plate and adapted for actuation by said actuating pin, said switch being connected to said first solenoid coil lead and adapted to switch electrical coupling with said first solenoid coil lead between first and second actuator leads in response to motion of said plunger.

Claim 13

The solenoid actuator of claim 9 wherein said switch has mechanical hysteresis so that said switch will not switch electrical coupling with said first solenoid coil lead between first and second actuator leads until said plunger is at least approaching the end of its tRavel at said extended position and said actuated position.

Claim 14

The solenoid actuator of claim 9 wherein said switch exhibits a time lag between motion of said plunger and the switching of electrical coupling with said first solenoid coil between first and second actuator leads.

Claim 15

The solenoid actuator of claim 9 further comprised of a source of direct current having first and second terminals, a current limiting means and a remote switching means schematically representable as a single pole, double-throw switch having a moving contact switchable between first and second fixed contacts, said second solenoid coil lead being coupled to said moving contact of said remote switch, said first and second actuator leads being coupled to first and second terminals of said source of direct current, respectively, said first fixed contact of said remote switch being coupled to said first terminal of said source of direct current and said second fixed contact of said remote switch being coupled, through a current limiting means, to said second terminal of said source of direct current.