Patent Abstract:
A safety switch prevents overflow of condensate that collects in the drain pan of an air-cooling system. The overflow safety switch attaches to the condensate drainage system and is electrically connected to a circuit of the air-cooling system, a power circuit, a control circuit and/or an alarm circuit. The switch includes a tube that extends within the condensate drain pan or any other water conducting point in the condensate drainage system. A reed switch is sealed within the tube and a float containing a magnet is moveably supported on the exterior of the tube. The float ascends or descends in response to the level of the liquid condensate within the drain pan. As the float moves relative to the tube, the magnet causes the reed switch to open, thereby interrupting operation of the air-cooling system and/or actuating the alarm circuit.

Full Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to electrical condensate overflow safety switches and, more particularly, to a float actuated magnetic reed switch attachable to the condensate drainage system of an air-cooling system for deactivating the system upon the level of condensate in the condensate drainage system reaching a predetermined level, thereby preventing collected liquid condensate from overflowing the condensate drainage system.  
         [0003]     2. Discussion of the Related Art  
         [0004]     Most residential and commercial air-conditioning and refrigeration units employ an evaporator coil to dehumidify and cool ambient air in dwellings, climate controlled storage spaces, work spaces, and the like. The evaporator coil is frequently located indoors, often above the occupied areas of the building that it serves. Since the coil is colder than the air being conditioned, it condenses water liquid while in operation. This condensate liquid is typically collected in a drain pan, usually positioned under the coil, with the drain pan having one or more outlet ports for attaching a drain pipe for outflow of the condensate. Many units have a secondary drain pan which may not have any outlets or connecting drain pipes. During normal operation, the condensate water liquid drains through one or more of the outlets of the main drain pan, through a drain pipe and out from the building. However, the drain pan, pan outlets and drain pipe, often become occluded by algae, mold, mildew, dirt and other accumulated debris. An occlusion in the outlets and/or drain pipes will eventually result in drain pan overflows that can cause water damage to building ceilings, walls, flooring, and associated building components, which necessitate costly repairs. In units which use a secondary drain pan, the liquid condensate will first overflow into the secondary drain pan. In some instances, the secondary drain pan will overflow and cause water damage.  
       SUMMARY OF THE INVENTION  
       [0005]     The present invention is directed to an overflow safety switch for attachment to the condensate drainage system of an air-cooling system in order to prevent overflow of condensate which collects in the condensate drainage system. In accordance with various embodiments of the invention, the overflow safety switch may be attached to one of the vertical side walls of the drain pan or through the bottom of the drain pan or drain pipe. In one embodiment, a brace attaches to the side wall of the drain pan and holds the overflow safety switch in a vertical upright position within the drain pan. In another embodiment, the overflow safety switch is mounted through the side wall and maintained in a generally horizontal position. In yet another embodiment, the overflow safety switch is mounted through the bottom of the drain pan so that the safety switch is held vertically upright within the drain pan. In still a further embodiment, the overflow safety switch is connected to a drain pipe or drain outlet extending from the drain pan.  
         [0006]     In each embodiment, the overflow safety switch is electrically connected to either a circuit of the air-cooling system, a power circuit or an alarm circuit. The overflow safety switch includes a tube which extends within any water conducting area of condensate drainage system. A reed switch is sealed within the tube and a float containing a magnet is moveably supported on the exterior of the tube. The float ascends or descends in response to the level of the liquid condensate within the condensate drainage system. As the float moves relative to the tube, the magnet causes the reed switch to open or close, thereby interrupting operation of the air-cooling system and/or actuating the alarm circuit. In yet a further embodiment, a normally open reed switch is connected to an alarm circuit, wherein movement of the float and magnet, in response to a rise in liquid in the drain pan, results in closing of the switch and activation of the alarm circuit.  
       OBJECTS AND ADVANTAGES OF THE INVENTION  
       [0007]     With the forgoing in mind, it is a primary object of the present invention to provide a condensate overflow safety switch for quick and easy attachment to the condensate drainage system of an air-cooling system, and wherein the overflow safety switch is structured and disposed to interrupt operation of the air-cooling system and/or activate an alarm upon the condensate liquid reaching a predetermined level at any point in the condensate drainage system, thereby preventing the condensate from overflowing the drain pan.  
         [0008]     It is a further object of the present invention to provide an overflow safety switch characterized by simple mechanical and electrical design, compactness, non-corrosive, low manufacturing complexity, water sealed design and high operational reliability.  
         [0009]     It is still a further object of the present invention to provide a condensate overflow safety switch which is structured and disposed for easy and quick attachment to the condensate drainage system of an air-cooling system, and wherein the overflow safety switch is structured and disposed to stop generation of condensate liquid in the event of a drain system occlusion, thereby preventing collected condensate liquid from overflowing the condensate drainage system which might otherwise result in property damage.  
         [0010]     These and other objects and advantages of the present invention are more readily apparent with referenced to the detailed description and accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     For a fuller understanding of the nature of the present invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings in which:  
         [0012]      FIG. 1  is a top perspective view of a condensate overflow safety switch and mounting bracket for attaching the safety switch to the side wall of a drain pan in an air-cooling system, in accordance with one preferred embodiment of the present invention;  
         [0013]      FIG. 2  is a cross-sectional view taken from the line indicated as  2 - 2  in  FIG. 1 ;  
         [0014]      FIG. 3  is a perspective view, shown in cutaway, illustrating a condensate overflow safety switch mounted through the side wall of a drain pan in an air-cooling system, in accordance with a second preferred embodiment of the present invention;  
         [0015]      FIG. 4  is a cross-sectional view taken along the line indicated as  4 - 4  in  FIG. 3 ;  
         [0016]      FIGS. 5 and 6  are side elevation views, shown in partial cross-section, showing the overflow safety switch of  FIG. 1  mounted to the side wall of a drain pan and illustrating a sequence of operation of the overflow safety switch between a low condensate level condition, wherein the overflow safety switch is in an normally closed circuit condition, and a raised condensate liquid level, wherein the overflow safety switch is in an open circuit condition to deactivate the air-cooling system;  
         [0017]      FIGS. 7 and 8  are side elevational views, shown in partial cross-section, showing the overflow safety switch of  FIG. 3  mounted to the side wall of a drain pan and illustrating a sequence of operation of the overflow safety switch between a low condensate level condition, wherein the overflow safety switch is in a normally closed circuit condition, and a raised condensate liquid level, wherein the overflow safety switch is in an open circuit condition to deactivate the air-cooling system;  
         [0018]      FIGS. 9 and 10  are side elevational views, shown in partial cross-section, showing the overflow safety switch mounted through the bottom of the drain pan, in accordance with yet another embodiment of the invention, and illustrating a sequence of operation of the overflow safety switch between a low condensate level condition, wherein the overflow safety switch is in a normally closed circuit condition, and a raised condensate liquid level, wherein the overflow safety switch is in an open circuit condition to deactivate the air-cooling system; and  
         [0019]      FIGS. 11 and 12  are side elevational views, shown in partial cross-section, showing the overflow safety switch mounted within a drain pipe leading from the drain pan of a condensate drainage system and illustrating a sequence of operation of the overflow safety switch between a low condensate level condition, wherein the overflow safety switch is in a normally closed circuit condition, and a raised condensate liquid level, wherein the overflow safety switch is an open circuit condition to deactivate the air cooling system. 
     
    
       [0020]     Like reference numerals refer to like parts throughout the several views of the drawings.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]     In each of the preferred embodiments, as shown throughout the drawings, the overflow safety switch assembly is generally indicated as  10  and includes a hollow tube  12  having an open end portion  14  and a closed end portion  16  with an outer surface  18  extending therebetween. A reed switch  20  has overlapping electrical contacts  22  connected to insulated wires  30 . The contacts  22  of the reed switch  20  and the exposed ends of the wires  30  are maintained within the hollow tube  12 . A sealing material  32 , for example plastic or epoxy, insulates the reed switch  20  and exposed ends of the wires  30  within the hollow tube  12 , thereby preventing contact with moisture. A portion of the outer surface  18  may be provided with threads  28  to facilitate attachment of the switch assembly to either a mounting clip  60 , as shown in  FIGS. 1 and 2 , or directly to the drain pan  100  of an air-cooling system, as seen in  FIGS. 3-4  and  7 - 10 . The threads  28  on the outer surface  18  of the hollow tube serve to permit adjustable positioning of the hollow tube relative to the drain pan  100 , as described more fully hereinafter. The overflow safety switch assembly may also be connected in-line to the drain pipe extending from the drain pan.  
         [0022]     Referring now to the embodiment shown in  FIGS. 1-2  and  5 - 6 , the overflow switch assembly  10  is provided with a float body  40  having a first end face  42  and a second end face  44 . A removable stopper mechanism  38 , such as a C-clip, is engaged onto the outer surface  28  of the hollow tube  12 , adjacent the closed end portion  16 . The float body  40 ′ is captivated on the hollow tube  12 , between the end portions  14 ,  16  and is slidably moveable between the stopper mechanism  38  and an upper shoulder  48  defined by a fixed hex nut configuration integrally formed or adjustably moveable on the hollow tube. The float body  40  is moveable between a lowered position, as seen in  FIGS. 2 and 5 , and a raised position, as seen in  FIG. 6 , in response to a raising condensate liquid level within the drain pan. The float body  40  is provided with a magnet  50  which may be exposed on the inner diameter of the float body. The magnet  50  is positioned in confronting relation to the outer surface  18  of the hollow tube and is disposed closer to the first end face  42  then the second end face  44  of the float body  40 . When the wires of the reed switch are connected to a circuit of the air-cooling system, the float body  40  is mounted with the first end face  42  facing toward the stopper mechanism  38  near the end portion  16 . When the wires are connected to an alarm circuit, the float body is mounted with the second end face  44  facing toward the stopper mechanism  38 . In the embodiment shown in  FIGS. 1-2  and  5 - 6 , the wires are connected to the circuit of the air-cooling system. In this instance, the contact elements  22  of the reed switch  20  are normally closed, maintaining a closed circuit condition, with the float body  40  at the lowered position, as seen in  FIGS. 2 and 5 . As the condensate liquid fluid level rises within the drain pan  100 , the float body  40  moves upwardly along the hollow tube  12 . Eventually, the magnet  50  is moved into position to cause the contact elements  22  of the reed switch  20  to separate, as shown by the float body position in  FIG. 6 , thereby opening the circuit and disabling the air-cooling system. Accordingly, when the condensate fluid level reaches a predetermined height in the drain pan  100 , as seen in  FIG. 6 , the reed switch  20  is opened to disable the air-cooling system and prevent further production of condensate liquid until the occlusion, blockage or other drainage problem is fixed.  
         [0023]     As seen in  FIGS. 1-2  and  5 - 6 , the overflow switch assembly  10  is supported vertically in the drain pan  100  so that the lower closed end portion  16  extends downwardly within the drain pan, with the closed end positioned in close spaced relation to the bottom surface of the drain pan. A clip  60  is used in this particular embodiment for supporting the overflow switch assembly  10  in this position. In a preferred embodiment, the clip  60  is formed from a single piece of material, such as a metal alloy, and includes a horizontal plate  62 , a vertical plate  64  and an inverted U-shaped portion  66  between the horizontal and vertical plates. The inverted U-shaped portion  66  is specifically structured and disposed to slip easily over the top edge of the drain pan and hold securely, as seen in  FIGS. 5 and 6 . Tabs  68  are provided on the vertical plate for frictional engagement against the outer surface of the drain pan side wall, thereby holding the clip  60  in place on the drain pan  100 . A screw  70  may be used for tightly securing the clip  60  onto the drain pan. Once the clip is attached to the drain pan, the position of the overflow switch assembly relative to the bottom of the drain pan may be adjusted by threadably advancing the hollow tube  12  relative to the horizontal plate  62  of the clip  60 . To this end, it should be noted that, in a preferred embodiment, a through hole is formed through the horizontal plate  62  of the clip and is specifically sized and configured for threadable engagement with the exterior threads  28  on the outer surface  18  of the tube  12 .  
         [0024]     Referring to the embodiment shown in  FIGS. 3-4  and  7 - 8 , a float body.  40 ′ is supported on the hollow tube  12  between the stopper mechanism  38  on the closed end portion  16  and the shoulder  48 . In this particular embodiment, the hollow tube  12  is mounted horizontally through the side wall of the drain pan  100  and the annular float body  40 ′ is provided with an elongate rectangular passage  41  extending between the first end face  42 ′ and the opposite second end face  44 ′. A magnet  50 ′ is embedded within a lower portion of the float body and is normally spaced from the outer surface  18  of the hollow tube, as seen in  FIG. 4 , a sufficient distance so that there is no magnetic influence exerted on the elements  22  on the reed switch  20  within the hollow tube  12 . As the condensate liquid level rises within a drain pan  100 , the float  40 ′ naturally rises relative to the hollow tube  12 , eventually reaching the position shown in  FIG. 8 . At this position, the magnet  50 ′within the lower portion of the float body  40 ′ is moved close to the outer surface  18  of the hollow tube  12 , resulting in a magnetic attraction between the magnet  50 ′and reed switch  20 , and causing the elements  22  of the reed switch to separate, thereby opening the circuit and disabling the air-cooling system. As seen in  FIG. 4 , a rubber O-ring seal  80  or washer is fitted about the outer surface  18 , at the threaded portion  28  of the hollow tube, and is placed against the outer surface of the side wall of the drain pan  100 , surrounding a through hole drilled through the drain pan. This seal  80  is held tight against the outer surface of the drain pan with a nut  82  or other fastening device which further serves to secure the switch assembly  10  in the horizontal position and attached to the side wall of the drain pan. The seal  80 , when tightly sandwiched between the nut  82  and outer surface of the drain pan side wall prevents leakage through the hole in the side wall of the drain pan.  
         [0025]     Referring to  FIGS. 9 and 10 , a further embodiment of the overflow switch assembly  10  is shown. In this particular embodiment, the structure of the switch assembly  10  is similar to that shown in connection with the embodiment of  FIGS. 1-2 . In the embodiment shown in  FIG. 9  and  10 , the hollow tube  12  and the reed switch  20  are mounted upwardly through the bottom of the drain pan so that the closed end portion  16  is spaced sufficiently above the inner bottom surface of the drain pan. To secure the overflow safety switch  60  to the drain pan  100 , a hole may be drilled through the bottom of the drain pan. The hole may be sized and configured for threadable, advanced passage of the threaded end portion of the hollow tube. Once securing and adjusting the hollow tube  12  at the desired height within the drain pan, a seal  80  may be placed around the hole in the bottom of the drain pan through which the hollow tube extends. Similar to the embodiment of  FIGS. 1-2 , the float  40  includes a magnet  50  which moves with the float body in relation to the outer surface  18  of the hollow tube  12  and the reed switch  20  therein. In the position shown in  FIG. 9 , the annular float body  40  is in lowered position, due to a low condensate liquid level in the drain pan  100 . As the condensate liquid level rises, the annular float body  40  moves upwardly along the hollow tube  12  causing the magnet  50  within the float body to separate. This results in opening the circuit and disabling the air-cooling system so that no further condensation is produced until the blockage or other drainage problem is fixed.  
         [0026]     Referring to  FIGS. 11 and 12 , the overflow switch assembly  10  is shown in yet a further embodiment wherein the switch assembly  10  is fitted to a pipe  120  with the hollow tube  12  extending through the pipe so that the upper shoulder  48 , closed end portion  16  and float body  40  are positioned within the pipe. As seen in  FIGS. 11 and 12 , the hollow tube  12  is fixed to the pipe  120  so that the outer surface  18  between the upper shoulder  48  and stopper mechanism  38  is vertically positioned, thereby permitting movement of the float body  40  between a lowered position and a raised position as the fluid liquid level in the pipe changes.  FIG. 11  illustrates a normal condition, wherein fluid is flowing freely and unobstructed through the pipe  120 . In this instance, the fluid level remains low with the float body  40  at the lowered position, thereby maintaining the overflow safety switch in a normally closed circuit condition. In the event the liquid level rises within the pipe  120 , due to a clog or other obstruction, the float body  40  rises, as seen in  FIG. 12 , to operate the overflow safety switch to the open circuit condition, thereby interrupting electric current flow through conductors  30 . The installation of the overflow safety switch in the manner shown in  FIGS. 11 and 12  is particularly useful in drain pipes of an air cooling system. In this instance, the overflow safety switch  10  is fitted in-line to the drain pipe leading from a drain pan of the air cooling system&#39;s drain system. In the event of a down line clog or other obstruction in the drain pipe  120 , the liquid level will rise in the pipe, as shown in  FIG. 12 . When the float body moves up to the raised position seen in  FIG. 12 , the circuit is opened and the air cooling system is disabled so that no further condensation is produced until the blockage in the drain pipe is removed. Accordingly, in the event of a blockage or other drainage problem, the air cooling system will be disabled with little or no liquid accumulation in the drain pan.  
         [0027]     While the instant invention has been shown and described in accordance with preferred and practical embodiments thereof, it is recognized that departures from the instant disclosure are contemplated within the spirit and scope of the present invention.

Technology Classification (CPC): 5