Abstract:
A pull switch incorporates a magnet pickup sensing of a selected one of a pulled, return or both of a pull string. A position of reset and trip states may be varied based on configuration. Because of these features, the pull switch can be used in many applications where a fixed position switch would not apply or would be hard to incorporate into the application. It can also be used in many fixed switch applications and allow for a more accurate switching. This switch can also allow for a much simpler installation with less hardware required then a fixed position switch.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates, in general, to status indicating devices and, in particular, to a pull switch. 
       BACKGROUND OF THE INVENTION 
       [0002]    The use of cables to trip switches is a known art. Generally, such switches had to be mounted in a fixed position and were set up to detect only a pre-set change of state. The problem with such switches is that they do not allow for any variation in the switch&#39;s reset location. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0003]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and, together with the general description of the invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the present invention. 
           [0004]      FIG. 1  is a perspective view of the pull switch of the present invention; 
           [0005]      FIG. 2  is an exploded view of the pull switch of  FIG. 1 ; 
           [0006]      FIG. 3  is a diagrammatic view of a pull switch in an initial, spooled condition at a counterclockwise-most position of a rotating portion of a position sensor; 
           [0007]      FIG. 4  is a diagrammatic view of the pull switch of  FIG. 3  after a pull string is drawn out causing the reed to change state because the magnet is moved from the location from which it was holding the reed in the opposite state to a wheel cam stop at a clockwise-most position; 
           [0008]      FIG. 5  is a diagrammatic view of the pull-return switch of  FIG. 11  after the pull string has been drawn out an additional amount with the rotating portion remaining stationary to set a desired operating length and set a tripped position so as to keep the magnet from tripping the reed again as this cable is continued to be pulled; 
           [0009]      FIG. 6  is a diagrammatic view of the pull switch of  FIG. 5  after the pull string has started to retract; 
           [0010]      FIG. 7  is a diagrammatic view of the pull switch of  FIG. 6  after the pull string has been allowed to retract to the counterclockwise most position indicating a return position. 
           [0011]      FIGS. 8-13  are additional diagrammatic views of the pull switch with the pull string in various positions. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0012]    Referring to  FIGS. 1-2 , one version of a pull switch  42  is disclosed having a housing  72 , including a top portion  74  and a bottom portion  76 , a pull string  35  attached to an anchor  56 , and wires  78  for the internal reed switch. A double-sided adhesive pad  79  on the housing  72  enables rapid installation. Referring to  FIG. 2 , the top portion  74  and bottom portion  76  of the housing  72  are adapted to receive a cable wheel assembly  82  therein. The top portion  74  may include a post  84  projecting inwardly from the central axis thereof that corresponds with a hole  86  in the bottom portion  76  for coupling the two halves of the housing  72 . 
         [0013]    An indicator (e.g., magnet) wheel  88 , inserted over the post  84 , is pressure loaded for frictional engagement against a cable wheel  94  by a load spring  90  (e.g., alternatively, a wave spring, PN CS050-L1, Smalley Steel Ring Company, Lake Zurich, Ill.) and a spring slide washer  92  positioned between the magnet wheel  88  and the top portion  74 . The magnet wheel  88  may include a wheel cam stop  96  that corresponds to a fixed stop  98  on the top portion  74  such that, when rotated, the magnet wheel  88  is limited by the fixed stop  98 . The magnet wheel  88  may further include a hole  100  in which a movable portion of a position sensor, depicted as a magnet  102 , may be retained. The magnet  102  may be located adjacent to the electrical contacts in the top portion of the housing  72 , depicted as a reed switch  80  such that rotation of the magnet wheel  88  operates the contacts  80 . Thus, the location sensor in particular is illustrated as a magnetic sensor that avoid contacts subject to wear and degradation. 
         [0014]    The magnet wheel  88  may be retained within the cable wheel  94  such that rotation of the cable wheel  94  correspondingly rotates the magnet wheel  88 . The cable wheel  94  may be placed over the post  84  and in one version is operably configured to rotate within the housing  72 . The rotation of the magnet wheel  88  may be limited by the wheel cam stop  96  on the magnet wheel  88  meeting up with the housing stop  98 . The cable wheel  94  may be circular in shape and may be configured such that the pull string  35  may be wound around the circumference thereof. The pull string  35  may be coupled with (e.g., tied to) the cable wheel  94  at a pair of radially spaced through holes  105  that communicate between an outer spool or reel recess  110  and an upwardly open cylindrical recess  114  that encompasses the magnet wheel  88 . The cable wheel is flipped over at  94 ′ to expose a central cylindrical hub portion  101  having a securing slot  104  or by any other suitable connection mechanism that receives an inner end  103  of a cable spring  106  that resides under the cable wheel  94  and has an outer end  107  that is received in a corner slot  109  that communicates with an upwardly open cylindrical recess  111  formed in the bottom portion  76  of the housing  72 . Thus, rotating the cable wheel  94  clockwise as viewed from above loads the cable spring  106 . After rotating the cable wheel  94  in one direction, the loaded cable spring  106  may allow the cable wheel  94  to have a return function that allows it to rotate in the opposite direction back to its starting position. 
         [0015]    Still referring to  FIG. 2 , in one version, the cable wheel  94  is rotated by pulling the pull string  35  wound thereabout. The free end of the pull string  35  may pass out of the housing  72  via an eyelet  108 B and notch  108 A and is connected at its terminus to an anchor  56 . In one version, the anchor  56  is affixed to a movable object, and the pull switch  42  are affixed to a fixed object. When the, movable object is moved away from the fixed object, the pull string  35  may be drawn out of the pull switch  42 , thereby rotating the cable wheel  94  located therein. Rotating the cable wheel  94  may correspondingly rotate the magnet wheel  88  such that the magnet  102  located thereon operates the reed  80 , indicating that the object has moved away from the fixed object. As the pull string  35  is pulled, the magnet wheel  88  is thus prevented from further rotation with the cable wheel  94  due to the wheel cam stop  96  abutting the fixed stop  98 . Thereby, the magnet  102  does not change the state of the reed  80 . 
         [0016]    It should be appreciated that a pull switch  42  consistent with aspects of the invention may be configured such that its tripped state and reset state are appropriate for a specific application. For instance, the size of the cable wheel  94  may be varied. The portion of rotation of a magnet wheel  88  that may be traversed prior to encountering the fixed stop  98  may vary. The number and/or positioning of magnets  102  and reed switches  80  may vary in order to provide a desired reset and trip state. It can also be used in many fixed switch applications and allow for a more accurate switching. This switch can also allow for a much simpler installation with less hardware required then a fixed position switch. 
         [0017]    Examples of the switch functionalities include a pull version or a return version. Below are both versions explained in detail relating to disputes of cable pull and/or return and are depicted in  FIGS. 3-13 . 
         [0018]    PULL EXAMPLE. When the pull string  35  is pulled from the pull switch  42 , it may trip a N.O. and/or a N.C. internal reed  80  to its abnormal state within a given “short” distance such as, for example, 0.25 inches or any other suitable distance based on switch design. Any further pulling of the pull string  35  may not change the state of the reed  80 . The maximum distance of the pull string  35  pull length may be about two feet or any other suitable length. The pull switch  42  may be reset, where the reed  80  is changed to its normal state, by retracting the pull string  35  into the pull switch  42  a given “long” distance such as, for example, 1.50 inches or any other suitable distance based upon switch design. Any further retracting of the pull string  35  may not change the state of the reed  80 . It will be appreciated that the distance stated as “short” and the distance stated as “long” are only for reference and that actual distances may be designed to any suitable length. This, for example, may include the “short distance” being longer then the actual stated “long distance” and vice versa. 
         [0019]    RETURN EXAMPLE. When the pull string  35  is retracted into the pull switch  42 , it may trip a N.O. and/or a N.C. internal reed  80  to its abnormal state within a given “short” distance such as, for example, 0.25 inches or any other suitable distance based on switch design. Any further retraction of the pull string  35  may not change the state of the reed  80 . The pull switch  42  may be reset, where the reed  80  is changed to its normal state, by pulling the pull string  35  a given “long” distance such as, for example, 1.50 inches or any other suitable distance based upon switch design. Any further pulling of the pull string  35  may not change the state of the reed  80 . It will be appreciated that the distance stated as “short” and the distance stated as “long” are only for reference and that actual distances may be set to any suitable length. This, for example, may include the “short distance” being longer then the actual stated “long distance” and vice versa. 
         [0020]    While the present invention has been illustrated by description of several embodiments and while the illustrative embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications may readily appear to those skilled in the art. 
         [0021]    Applications of the switch  20  are numerous, including any applications where fixed contacts are applied. 
         [0022]    While a reed sensor is depicted in the illustrative version, it should be appreciated that applications consistent with the present invention may include electrical contacts, microswitches, rotary encoder, proximity sensors, Hall effect sensors, LED,etc. that detect the pulled or returned condition of a pull switch.