SOLENOID HAVING INCREASED THROW CAPABILITY

• US 3,831,729 A
• Filed: 01/10/1973
• Issued: 08/27/1974
• Est. Priority Date: 11/30/1971
• Status: Expired due to Term

• Current Assignee: Genicom Corp.
• Original Assignee: Robert Howard
• Inventors: Howard, Robert
• Primary Examiner(s): Pulfrey, Robert E.
• Assistant Examiner(s): Rader, R. T.
• Application Number:
  US05/322,298
• Time in Patent Office: 594 Days
• Field of Search: 197/1 335/274,258 101/93C 251/129,139,141
• US Class Current: 400/124.17
• CPC Class Codes: B41J 2/285 of plunger type
• CPC Class Codes: B41J 9/38 Electromagnetic means
• CPC Class Codes: F16F 1/326 with a spiral-like appearance
• CPC Class Codes: H01F 7/13 characterised by pulling-force characteristics
• CPC Class Codes: H01F 7/1607 Armatures entering the winding
• CPC Class Codes: H02K 33/02 with armatures moved one way by energisation of a single coil system and returned by mechanical force, e.g. by springs

Abstract

A solenoid for actuating a print wire normally biased against the impact direction by novel spiral spring means. Energization of the solenoid coil rapidly moves the print wire in the impact direction against the bias of the spring. Release of the energy supplied to the solenoid coil causes very rapid return of the print wire to the non-printing (i.e., quiescent) position. The novel spiral spring structure experiences a substantially linear spring force upon deflection and provides significantly increased deflection as compared with conventional structures to allow for substantially rapid initial acceleration of the print wire in the impact direction while providing for rapid return of the print wire to the quiescent condition. The mounting of said spring reduces bouncing on overshooting.

Claims

1. A solenoid assembly comprising:

a housing;

an elongated substantially cylindrical stem having an axial opening of small diameter extending the length of said stem;

said stem being secured to the forward end of said housing;

an annular shaped coil positioned within said housing and surrounding a portion of said stem;

a closure cap threadedly engaging the rearward end of said housing;

an armature positioned within said housing and along the axis of said housing, at least the forward portion of said armature extending to a position relative to said coil;

whereby said armature is activated and moved by the magnetic field generated by the coil when energized;

a slender elongated wire positioned within the axial opening of said stem and having its forward end extending beyond the forward end of said stem and its rearward end secured to the forward end of said armature;

circular shaped spring means having a circular outer periphery and having its central portion joined to the rearward portion of said armature;

said housing having an annular shoulder engaging the periphery of said spring means;

said spring means being formed of a resilient metallic sheet and having a pair of spiral shaped slots encircling said central portion and interleaving one another;

each of said spiral shaped slots having an inner end portion near said central portion and an outer end portion near said spring outer periphery and encircling said central portion at least once.

2. The solenoid assembly of claim 1 wherein the inner ends of said slots lie on opposite sides of said central portion.

3. The solenoid assembly of claim 2 wherein the inner ends of said slots lie along a common diameter of said spring.

4. The solenoid assembly of claim 1 wherein the outer ends of said slots lie on opposite sides of said central portion.

5. The solenoid assembly of claim 4 wherein the outer ends of said slots lie along a common diameter of said spring.

6. The solenoid assembly of claim 1 wherein said spring is formed from a sheet of spring steel.

7. The solenoid assembly of claim 1 wherein said spring is adapted to exert a rearwardly directed force on said armature to normally hold said print wire in the non-impact position when said solenoid coil is deenergized, said coil being adapted to overcome the rearward directed force of said spring when energized to rapidly move said print wire toward the impact position, and thereby flex said spring to cause said print wire to return rapidly to the non-impact position when said coil is deenergized;

said spring being adapted to engage said closure cap in returning to the non-impact position, which closure cap eliminates bounce.

8. The solenoid assembly of claim 1 wherein each of said spiral slots represents an Archimedian spiral.

9. The solenoid assembly of claim 1 wherein each of said spiral shaped slots represents an involute of a line.

10. A solenoid assembly comprising:

a hollow substantially cylindrical housing;

an elongated substantially cylindrical stem having an axial opening of small diameter extending the length of said stem;

said stem being secured to the forward end of said housing;

an annular shaped coil positioned within said housing and surrounding a portion of said stem;

a closure cap threadedly engaging the rearward end of said housing;

an armature positioned within said housing and along the axis of said housing, at least the forward position of said armature extending to a position relative to said coil;

whereby said armature is activated and moved by the magnetic field generated by the coil when energized;

a slender elongated wire positioned within the axial opening of said stem and having its forwarD end extending beyond the forward end of said stem and its rearward end secured to the forward end of said armature;

circular shaped spring means having its central portion joined to the rearward portion of said armature;

said housing having an annular shoulder engaging the periphery of said spring means;

said spring means being formed of a resilient metallic sheet and comprising an inner ring and a concentric outer ring;

a pair of spiral-shaped spring portions each encircling the inner ring at least once and having their inner ends adjacent the inner ring being integrally joined to said inner ring and having their outer ends adjacent said outer ring being integrally joined to the outer ring.

11. The assembly of claim 10 whereby the outer ends of said spiral-shaped spring portions are diametrically opposite one another.

12. The assembly of claim 10 wherein the inner ends of said spiral-shaped spring portions are diametrically opposite one another.

13. The assembly of claim 10 wherein the free ends of the outer extremities of said spiral-shaped spring portions are transversely aligned to their spiral portions, whereby forming an integral joining section between said spiral-shaped portions and said outer ring to significantly reduce torsional stresses during deflection of the spring means.

14. The assembly of claim 10 wherein the free ends of the inner ends of said spiral-shaped portions are transversely aligned to their spring spiral-shaped portions, thereby forming an integral joining section between said spring spiral portion and said inner ring to significantly reduce torsional stresses during deflection of the spring means.