Device to control speed and torque of line return in spring drive device

Abstract

A governing device including a return spring and a spool upon which a line or cord is wound, includes on a fixed housing element a magnetic or a conductive material and on the rotating portion of the spool respectively either a magnet or a layer of conductive material is provided. When the line or cord is retracted by the spring, a hysteresis loop is formed in the conductive material by the magnet causing an eddy current which slows down the rate of retraction of the line to provide safety in the rate of return of the line or cord.

What is claimed is:  
     
         1 . A retractable line or cord device comprising: 
 a rotatable spool having means for retaining a flexible line or cord;    a power spring mounted in driving relationship to rotate said spool;    at least a portion of said spool comprising a conductive portion or a portion of magnetic material capable of generating magnetic field lines; and    a fixed member located adjacent said spool; said fixed member comprising at least a portion of magnetic material capable of generating magnetic field lines if the spool comprises said conductive portion and produce eddy currents in said spool conductive portion; and    if said spool comprises a portion of magnetic material capable of generating magnetic field lines, said fixed member comprises a conductive portion.    
     
     
         2 . A retractable line or cord device according to  claim 1  wherein said portion of magnetic material capable of generating magnetic field lines comprises a magnet assembly including a plurality of north and south pole portions.  
     
     
         3 . A retractable line or cord device according to  claim 2  wherein said conductive material comprises at least one material selected from copper, aluminium, silver, gold, steel and platinum.  
     
     
         4 . A retractable line or cord device according to  claim 3  wherein said conductive material comprises a disc made of said conductive material  
     
     
         5 . A retractable line or cord device according to  claim 2  wherein said spool includes a spool assembly comprising upper and lower magnet assemblies which generate magnetic fields respectively in upper and lower conductive plates located in said fixed member to oppose rotation and slow down the rate of retraction.  
     
     
         6 . A retractable line or cord device according to  claim 2  wherein said spool includes a spool assembly comprising a lower magnet assembly which generates magnetic fields in said lower conductive plate located in said fixed member to oppose rotation and slow down the rate of retraction.  
     
     
         7 . A retractable line or cord device according to  claim 2  wherein said spool includes a spool assembly comprising of two lower magnet assemblies, which generate a magnetic field in said lower rotating conductive disc, located between said magnet assemblies; and a manually adjustable rotational member, containing one of said magnets which allow radial alignment of said magnets, in relation to each other, that allow the generating of variable strength magnetic fields in said lower rotating conductive disc to oppose rotation and variably slow down the rate of retraction.  
     
     
         8 . A retractable line or cord device according to  claim 2  wherein a gear assembly is in driving engagement with said coil spring, and said coil spring includes a first shaft vertically extending within said coil spring and engaging said gear assembly.  
     
     
         9 . A retractable line or cord device according to  claim 8  wherein said gear assembly includes a first large gear; said large gear being in driving engagement with a small gear.  
     
     
         10 . A retractable line or cord device according to  claim 9  wherein said small gear being in driving engagement with a second vertically extending shaft; said second shaft being in driving engagement with a second large gear; said second large gear being in driving engagement with a small gear, laterally spaced therefrom; said second small gear being in driving engagement with a vertically extending spool shaft; said spool shaft being integral with said spool; said spool having a line or cord wound about a spool core.  
     
     
         11 . A retractable line or cord device according to  claim 10  wherein said line or cord extends outwardly from said spool and anchoring means are provided for anchoring said line or cord located outside said retraction device housing.  
     
     
         12 . A retractable line or cord device according to  claim 10  wherein brake means are provided for maintaining said power spring in tension position; and means for releasing said brake means are provided to allow said power spring to drive said first gear, said second gear, said third gear, said fourth gear, and said spool to retract said line or cord.  
     
     
         13 . A retractable line or cord device comprising: 
 a rotatable spool having means for retaining a flexible line or cord;    a power spring mounted in driving relationship to rotate said spool;    at least a portion of said spool comprising a conductive portion and    a fixed member located adjacent said spool; said fixed member comprising at least a portion of magnetic material capable of generating magnetic field lines in said spool conductive portion and produce eddy currents in said spool conductive portion.    
     
     
         14 . A retractable line or cord device according to  claim 13  wherein said portion of magnetic material capable of generating magnetic field lines comprises a magnet assembly including a plurality of north and south pole portions.  
     
     
         15 . A retractable line or cord device according to  claim 14  wherein said conductive material comprises a disc.  
     
     
         16 . A retractable line or cord device according to  claim 14  wherein said conductive material at least one material selected from copper, aluminium, silver, gold, steel and platinum.  
     
     
         17 . A retractable line or cord device comprising: 
 a rotatable spool having means for retaining a flexible line or cord;    a power spring mounted in driving relationship to rotate said spool;    at least a portion of said spool comprising a portion of magnetic material capable of generating magnetic field lines in an adjacent conductive portion;    and a fixed member located adjacent said spool;    said fixed member comprising a conductive portion which during rotation of said spool receives magnetic field lines from said magnetic material in said spool, and generates eddy currents in said conductive material.    
     
     
         18 . A retractable line or cord device according to  claim 17  wherein said portion of magnetic material capable of generating magnetic field lines comprises a magnet assembly including a plurality of north and south pole portions.  
     
     
         19 . A retractable line or cord device according to  claim 17  wherein said conductive material comprises at least one material selected from copper, aluminium, silver, gold, steel and platinum.  
     
     
         20 . A retractable line or cord device according to  claim 19  wherein said conductive material comprises a disc made of said conductive material.