Abstract:
Eddy current braking apparatus includes a linear array of spaced apart permanent magnets arranged for defining a slot therebetween. A diamagnetic or non-magnetic fin is disposed and sized for movement through the slot. A pivotal linkage enables the magnets to move with respect to the fin from a spaced apart first position to a second position in which the fin passes through the slot. A control mechanism selectively moves the magnets between the first and second positions.

Description:
BACKGROUND 
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to moving apparatus requiring relatively rapid deceleration to a lower velocity upon reaching a predetermined point along its path of movement. 
     SUMMARY OF THE INVENTION 
     In accordance with the practice of the present invention, an object, apparatus or vehicle which is moving along a given path is provided with braking means which is automatically actuated to reduce the object velocity on reaching a predetermined point along the path of movement. In a first embodiment, a linear array of spaced apart permanent magnets are arranged along the object path of movement from the predetermined braking point to a further point sufficient to accomplish the desired amount of braking. The object includes a diamagnetic or nonmagnetic member which extends between the spaced apart magnets on the object reaching the predetermined point along the movement path and remains so-positioned throughout the full length of the array. The relative movement between the magnets and the member causes eddy currents to be induced in the member resulting in a braking force being exerted on the member and thus on the object. 
     In another embodiment, the moving object includes one or more sets of spaced apart permanent magnets affixed thereto. On the object reaching the predetermined braking point of the path of movement, it encounters a diamagnetic or nonmagnetic member that extends between the sets of spaced apart magnets producing the eddy current braking force as in the first embodiment. 
     In yet another version, actuation means are carried by the object for selectively locating the diamagnetic/nonmagnetic member or magnets, as the case may be, in operating relation with the magnets or member arranged along the path of movement on the object reaching the predetermined point of the path. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and advantages of the present invention will become more readily apparent upon reference to the following detailed description and upon reviewing the attached drawings, in which: 
     FIG. 1 is a perspective view of one embodiment of the present invention; 
     FIG. 2 is a perspective view of one half of a linear array of magnets for use in the invention; 
     FIG. 3 is an end elevation of FIG. 1; 
     FIG. 4 is an end elevational view of a magnet array of a second embodiment of the invention; 
     FIG. 5 is an end elevational view of a magnet array of a third embodiment of the invention; 
     FIG. 6 depicts an elevational schematic view of a braking system for operation in a vertical direction, shown disengaged; 
     FIG. 7 shows the vertical system of FIG. 6 engaged; 
     FIG. 8 shows a selectively actuatable braking system disengaged; and 
     FIG. 9 shows the system of FIG. 8 engaged. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     For the ensuing description of a first embodiment of braking apparatus  10  of this invention for an object  12 , reference is made particularly FIGS. 1-3. The object  12  is shown in generalized form only and is contemplated for movement in the direction of the arrow. Affixed to the object is a T-shaped member or fin  14  which extends outwardly from the object and also moves with the object in the direction of the arrow. 
     At some point along the path of movement there are mounted first and second laterally spaced magnet arrays  16  and  18 . Each array includes an elongated support wall  20  which is L-shaped in cross-section and on a lateral surface thereof there are provided a linear series of permanent magnets  22 , with adjacent magnets separated by diamagnetic or nonmagnetic spacers  24 . More particularly, the magnets alternate in polarity as indicated by the identification letters “S” and “N”. Also, the space  26  between the arrays is so-dimensioned and arranged with respect to the object path of movement that the fin will move along the space directly opposite the magnets and spacers, but remaining out of physical contact with either the magnets or spacers. 
     On the object reaching the magnet arrays  16  and  18  and the fin  14  passes through the magnetic field existing in the space  26 , an electric current (eddy current) is induced in the fin which reverses as the fin passes from a magnet of one polarity to a magnet of opposite polarity. These eddy currents produce a force exerted on the fin (and object) of such direction as to reduce the velocity of movement of object and fin. It is this deceleration that produces the “braking” of the present invention. 
     Although the above-described first embodiment includes movement of the object and fin past fixedly located magnet arrays, the magnet arrays can just as well be moved past a stationary object and fin. All that is needed to achieve the braking effect is relative movement between the magnets and fin. Since usually the object is moving, in that case the magnet arrays would be carried by the object and the fin fixedly mounted adjacent the path of movement. The choice of which technique to employ depends upon the particular application. 
     In its more general aspects, the invention can be advantageously employed for braking a large variety of moving objects. As an excellent example, eddy current braking for elevators could be highly advantageous as an emergency measure where normal operation has somehow been interfered with or disrupted. Also, many amusement park rides could benefit by having eddy current braking devices to retard excessive speed as the “ride” vehicle takes a corner or drops at a severe angle. 
     It is important to note that the described eddy current braking system may be adapted to an object moving along a horizontal path, a vertical path, or at any intermediate angular path. Rotary motion can be braked by the same techniques with an appropriate modification of magnet holding apparatus and fin design. 
     Turning now to FIG. 4, the magnetic array portion of the invention is seen to be modified to include a member  28  extending across the air gap  26  from one support wall  20  to the other below the magnets  22  sufficiently that no contact is made with a fin  14  passing therethrough. Preferably the member  28  is made of a ferromagnetic material which improves magnetic coupling during operation of the braking system. 
     A further embodiment is that shown in FIG. 5 where a magnetic material lower wall  30  extends between the two support walls just below the point of maximum reaching of the fin moving through space  26 . This construction enhances the magnetic characteristics of the overall system in a substantial way. 
     FIGS. 6 and 7 depict a braking system of the invention as particularly applied to a vertically extending cable, rope or chain  32  which is automatically braked on the cable tension increasing beyond a prescribed minimum. A magnet carrier  34  is interconnected to a track or slide device  36  via a four-bar pivotal linkage  38 . The magnet carrier also includes a base  40 . A fin  42  is mounted adjacent the magnet carrier  34  and magnetically coupled with the magnets on the cable  32  changing from a slack condition (FIG. 6) to one of tension thereby producing eddy current braking as already described. A counterweight  44  hangingly connected to the magnet carrier  34  maintains the braking system disengaged while the cable is slack (FIG.  6 ). However, the cable which passes over pulleys  46  and  48  on experiencing tension engages the braking system (FIG.  7 ). 
     FIGS. 8 and 9 show an eddy current braking system which does not automatically operate open relative movement being established, but is selectively actuatable depending upon any of a number circumstances indicating the need or desirability for braking. An object  52  with a brake fin  54  interconnected therewith moves generally along the direction  56  which normally will pass by a magnet carrier  58  beyond the range of substantial magnetic interaction (FIG.  8 ). The object  52  and fin  54  are provided with means  60  selectively actuatable for moving them toward the magnet carrier so as to effect magnetically coupling therewith (FIG. 9) and achieve braking. 
     Although there has been hereinabove described a specific arrangement of eddy current braking apparatus in accordance with the present invention, for the purpose of illustrating the manner in which the invention may be used to advantage, it should be appreciated that the invention is not limited thereto. Accordingly, any and all modifications, variations, or equivalent arrangements which may occur to those skilled in the art, should be considered to be within the scope of the invention as defined in the appended claims.