Patent Publication Number: US-8993903-B2

Title: Sealed dual plunger switch assembly with simultaneity

Description:
TECHNICAL FIELD 
     Embodiments are generally related to electrical switches. Embodiments are also related to plunger actuating mechanisms utilized in switching devices. Embodiments are also related to sealed switch sub-assemblies within a common enclosure for maintaining actuation inputs at different plunger locations operating simultaneously within a fixed distance from the assembly&#39;s mounting surface. 
     BACKGROUND OF THE INVENTION 
     Many types of switch mechanisms are utilized in residential, commercial, industrial and military applications. A particular application of switch mechanisms of this type relate to pushbutton switches that comprise a plunger that is movable relative to a base along an axis and which causes actuation of switching components when the plunger is depressed. Typically, the plunger is connected to a button that is depressible by a human finger. Some switch mechanisms cause actuation of a switch upon each depression of the button and plunger while other switch applications, referred to as alternate action devices, actuate on one push and release of the button and undo the actuation on a subsequent push and release of the button. 
     Generally, a plunger switch is mounted to an electric appliance to control a lamp, a motor, a heater and so forth. Due to external pressure generated by electrical and mechanical elements, a point of contact of the plunger switch engages the electric appliance. Meanwhile, when the external pressure is eliminated, the contact of the plunger switch returns to an original position thereof, thus maintaining an operable position. 
     In many switch designs and other mechanically actuated devices, the plunger is utilized as the input mechanism to force some other action within the surrounding enclosure (i.e., case or housing). Plungers come in all different shapes and sizes but are usually retained in their respective enclosures by similar means. In most cases, a spring or similar feature can provide resistance to the actual movement of the plunger within the enclosure. 
     Many electrical switches are of the type which encounter “overtravel” after the state of the electrical connection of the switch has been altered. In most instances, an actuator is employed to operate the switch. The actuator and its associated components usually go through a “pretravel” before electrical connection is made or the switch state is altered, which sometimes is termed the “operating point”. The actuator and/or its associated components go through an overtravel condition of movement after the operating point. Upon release of the actuator, reverse movement usually takes place and a “release point” occurs when the electrical connection and its associated circuit is transferred back to its original state. This usually occurs sometime during return movement of the actuator. 
     Plunger switch design inherently requires that actuating plunger travel must be the same as the return plunger travel plus movement differential before the switch can transfer the circuit to the original position. It further means that the actuation device and/or the switch mounting method must be designed to accommodate manufacturing tolerances in the involved apparatus components and still provide sufficient movement so that plunger travel through the operating point into the overtravel region will ensure that the switch can change states each time it is actuated. In many instances the attainment of these relations is complicated by the fact that normal manufacturing tolerances alone can be greater than the total travel (return plunger travel plus movement differential plus maximum permitted overtravel) of the switch thereby requiring the use of expensive and complicated mounting bracketry. 
     Based on the foregoing it is believed that a need exists for an improved sealed switch assembly that can receive actuation inputs at two different plunger locations. Additionally, a need exists for achieving the desired operating point of each plunger in a way such that they operate simultaneously within a fixed distance from the assembly&#39;s mounting surface. 
     BRIEF SUMMARY 
     The following summary is provided to facilitate an understanding of some of the innovative features unique to the embodiments disclosed and is not intended to be a full description. A full appreciation of the various aspects of the embodiments can be gained by taking the entire specification, claims, drawings, and abstract as a whole. 
     It is, therefore, one aspect of the present invention to provide for improved electrical switches. 
     It is another aspect of the present invention to provide for improved plunger actuating mechanism. 
     It is another aspect of the present invention to provide for an improved apparatus and method for maintaining dual plunger within a sealed switch enclosure. 
     The aforementioned aspects and other objectives and advantages can now be achieved as described herein. A sealed dual plunger switch assembly includes two switch sub-assemblies comprising a plunger actuating mechanism and basic switches. The sub-assemblies can be inserted into an overall enclosure using shims in order to position their operate points in the desired range relative to the enclosure&#39;s mounting surface. The enclosure is then sealed using a combination of covers, gaskets, o-rings, connectors and potting. The dual plunger switch assembly simultaneously receives actuation inputs at two plunger locations, and the plungers actuate two switch sub-assemblies within a fixed distance from the assembly&#39;s mounting surface. The dual plunger switch assembly can also receive only one actuation input, in which case only one switch sub-assembly would be actuated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying figures, in which like reference numerals refer to identical or functionally-similar elements throughout the separate views and which are incorporated in and form a part of the specification, further illustrate the embodiments and, together with the detailed description, serve to explain the embodiments disclosed herein. 
         FIG. 1  illustrates a perspective view of a dual plunger switch assembly, in accordance with a preferred embodiment; 
         FIG. 2  illustrates a side perspective view of the dual plunger switch assembly depicted in  FIG. 1 , in accordance with a preferred embodiment; 
         FIG. 3  illustrates a top view of the dual plunger switch assembly depicted in  FIG. 1 , in accordance with a preferred embodiment; 
         FIG. 4  illustrates a bottom view of the dual plunger switch assembly depicted in  FIG. 1 , in accordance with a preferred embodiment; 
         FIG. 5  illustrates another perspective view of the dual plunger switch assembly, in accordance with a preferred embodiment; 
         FIG. 6  illustrates side perspective view of the dual plunger switch assembly depicted in  FIG. 5 , in accordance with a preferred embodiment; 
         FIG. 7  illustrates a sectional view A-A of the dual plunger switch assembly depicted in  FIG. 6 , in accordance with a preferred embodiment; 
         FIG. 8  illustrates a high-level flow chart of operations depicting a method for forming a sealed dual plunger switch assembly, in accordance with a preferred embodiment; and 
         FIG. 9  is a schematic diagram of dual plunger switch enclosure apparatus. 
     
    
    
     DETAILED DESCRIPTION 
     The particular values and configurations discussed in these non-limiting examples can be varied and are cited merely to illustrate at least one embodiment of the invention and are not intended to limit the scope thereof. 
     Referring to  FIG. 1  a perspective view of a dual plunger switch assembly  100  is illustrated, in accordance with a preferred embodiment. Note that in  FIGS. 1-7 , identical or similar parts or elements are generally indicated by identical reference numerals. The dual plunger switch assembly  100  includes an enclosure  116  which surrounds a switch sub-assembly  102  and a switch sub-assembly  112 . The switch assembly  100  further includes a pair of electrical connectors  110  and  120  which extends through a cover plate  118  attached to the enclosure  116  for communication with an external circuit. 
     Referring to  FIG. 2  a side perspective view of the dual plunger switch assembly  100  depicted in  FIG. 1  is illustrated, in accordance with a preferred embodiment. 
     Referring to  FIG. 3  a top view of the dual plunger switch assembly  100  depicted in  FIG. 1  is illustrated, in accordance with a preferred embodiment. As indicated in  FIG. 3 , the dual plunger switch assembly  100  includes the switch sub-assembly  102 , the switch sub-assembly  112 , mounting holes  114  and the enclosure  116 . 
     Referring to  FIG. 4  a bottom view of the dual plunger switch assembly  100  depicted in  FIG. 1  is illustrated, in accordance with a preferred embodiment. As indicated in  FIG. 4  terminal contacts  140  are disposed within the openings formed in the electrical connectors  110  and  120 , which provide communication to an external circuit. 
     Referring to  FIG. 5  another perspective view of the dual plunger switch assembly  100  is illustrated, in accordance with a preferred embodiment. 
     Referring to  FIG. 6  side perspective view of the dual plunger switch assembly  100  depicted in  FIG. 5  is illustrated, in accordance with a preferred embodiment. 
     Referring to  FIG. 7  a cross-sectional view A-A of the dual plunger switch assembly  100  depicted in  FIG. 6  is illustrated, in accordance with a preferred embodiment. The space between the switch sub-assembly bushings  122  and enclosure  116  and cover plate  118  defines an elongated interior cavity  144  as shown in  FIG. 7  which houses the operative components of the switch assembly  100 . The switch sub-assemblies  102  and  112  have a plunger  104  exposed exteriorly of the bushing  122  and a lower plunger portion  108  includes an enlarged diameter to define a shoulder  136 , which rests against bushing  122  as shown in  FIG. 7  when the switch assembly  100  is in its original or un-operated state. An O-ring  106  surrounds plunger  104  to seal the interior of bushing  122 . 
     An ice scraper  130  as shown in  FIG. 7  is provided above the O-ring  106  to protect the o-ring. The switch sub-assemblies  102  and  112  are positioned within the enclosure  116  using shims  134  to fix the normal and actuated positions of the switch sub-assemblies  102  and  112 . The sealed switch assembly  100  can receive actuation inputs to the switch sub-assemblies  102  and  112  and the operating point for switch sub-assemblies  102  and  112  can be simultaneous and within about 0.010 inches of a fixed distance from the assembly&#39;s mounting surface. The switch sub-assemblies  102  and  112  can be fixed to the collar  124  by appropriate means, and the collar  124  is connected to the enclosure  116  using screws  114 . O-rings  146  surround switch sub-assemblies  102  and  112  and seal between these sub-assemblies and enclosure  116 . 
     Compression springs  128  as shown in  FIG. 7  bias the plungers  108  away from the actuated position toward the normal position. The switch sub-assemblies  102  and  112  can be depressed which commences compressing a first compression spring  128 . As first compression spring  128  is compressed this allows internal plunger  132  to act against lever  138  which actuates the basic switch elements  142  causing the electrical contacts to change state. The change in state of the electrical contacts is communicated to the external circuit via conductors  148  fixed to the terminals of switch elements  142  and the electrical contacts  140  of electrical connectors  110  and  120 . Second compression spring  126  as shown in  FIG. 7  will also compress when the switch sub-assemblies  102  and  112  are actuated by an amount greater than that needed to cause the electrical contacts to change state. The spring  128  as shown in  FIG. 7  serves as a return spring for the plungers  108  when pressure on the switch sub-assemblies  102  and  112  is released. 
     Referring to  FIG. 8  a high-level flow chart of operations depicting a method for forming a sealed dual plunger switch assembly  800  is illustrated, in accordance with a preferred embodiment. Two plunger switch subassemblies  102  and  112  comprising a plunger actuating mechanism can be provided, as shown at block  810 . The sub-assemblies  102  and  112  can then be inserted into an enclosure  116  utilizing shims  134  in order to achieve desired operating point relationship, as illustrated at block  820 . Thereafter, as depicted at block  830 , the enclosure  116  can be sealed utilizing a combination of covers  118 , gaskets, o-rings  106  and  146 , connectors  110  and  120  and potting. Actuation inputs can be applied either individually or simultaneously to the two plunger switch sub-assemblies  102  and  112 , as shown at block  840 . 
       FIG. 9  is a dual plunger switch enclosure apparatus, comprising an enclosure  116  having a plurality of walls, a plurality of electrical contacts  140  associated with said enclosure  116  for establishing an electrical connection, and at least two plunger switch sub-assemblies  102  and  112  associated with said enclosure  116  which are movable over a predetermined range, in order to alter the state of electrical connection in response to movement of said at least two plungers from a normal position to an actuated position. The apparatus further comprising a plurality of shims  134  associated with said at least two switch sub-assemblies  102  and  112  being inserted into said enclosure  116  in order to achieve an operating point of said at least two switch sub-assemblies  102  and  112  in a desired range. 
     It will be appreciated that variations of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also that various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.