Abstract:
A mounting structure ( 34 ) for receiving a sensor ( 18 ) having a sensing portion ( 26 ) and a base portion ( 30 ) includes a substantially flat sheet of material ( 20 ) having a first surface ( 20   a ), a second surface ( 20   b ) opposite the first surface ( 20   a ), and an aperture ( 36 ). The aperture ( 36 ) is configured such that the sensing portion ( 26 ) of the sensor ( 18 ) is passable through the aperture ( 36 ), and the base portion ( 30 ) is not passable through the aperture ( 36 ), but instead rests on the first surface ( 20   a ). The mounting structure ( 34 ) also includes a pair of tabs ( 38 ) that extend in a downward direction away from the second surface ( 20   b ) of the sheet of material ( 20 ) and are configured to immobilize the sensor ( 18 ) within the aperture ( 36 ).

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to a mounting structure for securing a sensor. More particularly, the present invention relates to a mounting structure for receiving and securing a sensor to a control box of a condensing unit. 
     A split system heating and/or cooling system includes an outdoor unit, such as a condensing unit, and an indoor unit, such as an evaporator unit. For operation of the condensing unit, an outdoor ambient air temperature is sensed by a temperature sensor, such as a thermistor, and electrically transmitted to a controller of the unit located within a control box. 
     In some designs, if the thermistor is located outside of a control box of the condensing unit, the thermistor may be exposed to the sun and thus may provide inaccurate temperature data. In other designs, the thermistor may be located inside the condensing unit, in part to avoid exposure to the sun. In that case, the thermistor may be exposed to wanner air circulating through a coil assembly inside the condensing unit and/or heat given off by a compressor inside the condensing unit, both of which may result in an inaccurate temperature reading. In some designs, the thermistor may be fastened to the inside of the condensing unit through the use of wire ties, which may be labor intensive, and again, may result in inaccurate temperature data. 
     There is a need for a temperature sensor locatable in a position to accurately measure an outside ambient air temperature, yet be easily mounted to a part of the condensing unit such that the sensor is secure and under minimal strain. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is a mounting structure for receiving a sensor having a sensing portion and a base portion. The mounting structure includes a substantially flat sheet of material having a first surface, a second surface opposite the first surface, and an aperture configured such that the sensing portion of the sensor is passable through the aperture, and the base portion is not passable through the aperture, but rests on the first surface. The mounting structure also includes a pair of tabs that extend in a downward direction away from the second surface of the sheet of material and are configured to immobilize the sensor within the aperture. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a perspective view of a condensing unit with a cover removed from a control box of the unit. 
         FIG. 1B  is an enlarged view of a portion of the control box from  FIG. 1A  illustrating a thermistor secured within the control box. 
         FIG. 1C  is a perspective bottom view of the thermistor and the control box from  FIG. 1B . 
         FIG. 2  is a perspective view of the thermistor of  FIGS. 1A-1C . 
         FIG. 3  is a perspective top view of a bottom wall of the control box of  FIG. 1A  to illustrate an aperture in the wall configured for receiving and securing the thermistor of  FIG. 1 . 
         FIG. 4  illustrates a process of inserting the thermistor of  FIG. 2  into the aperture of  FIG. 3 . 
         FIG. 5  illustrates a process of securing the thermistor within the aperture. 
         FIG. 6  is a perspective bottom view of the thermistor once it is secure inside the aperture. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention is a structure and method for mounting a sensor (such as a thermistor) to a surface (such as a wall or plate of a control box or housing).  FIG. 1A  is a perspective view of condensing unit  10  of an air conditioning or heat pump system. Condensing unit  10  is shown to aid in the description of the present invention and is not intended to limit the scope of the present invention. Condensing unit  10  includes fan  12 , coil assembly  14 , and control box  16 . 
     When condensing unit  10  is used as part of an air conditioning unit, fan  12  draws air from outside condensing unit  10  across coil assembly  14 . Refrigerant is enclosed in tubing used to form a coil in coil assembly  14 . As the refrigerant passes through the coil of coil assembly  14  and the cooler air from outside condensing unit  10  passes across coil assembly  14 , the air absorbs heat from coil assembly  14 , which causes the refrigerant to condense. The resulting cooled liquid refrigerant then flows to an evaporator, which is part of a corresponding indoor unit, and the evaporator utilizes the refrigerant to cool air. When condensing unit  10  is used as part of a heat pump system, coil assembly  14  acts as an evaporator coil to extract heat from the surrounding air. 
     Condensing unit  10  includes control box  16 . As shown in  FIG. 1A , a cover (not shown) has been removed from control box  16 . Control box  16  includes circuit board  17  which controls an overall operation of outdoor condensing unit  10  and the corresponding indoor unit. 
       FIG. 1B  is an enlarged view of control box  16  from  FIG. 1A . Control box  16  includes thermistor  18 , which is secured within an aperture or cut-out in bottom wall  20  of control box  16 . Thermistor  18  is configured to measure an ambient air temperature, and includes wires  22  which are also connected to circuit board  17  in order to relay signals from thermistor  18  to circuit board  17 . Additional wires may be connected to circuit board  17  to connect various other components of unit  10  to circuit board  17 ; for clarity these other wires have not been shown in  FIGS. 1A-1C . 
       FIG. 1C  is a perspective bottom view of control box  16  and thermistor  18  from  FIG. 1B . As explained in more detail below, thermistor  18  is configured such that a portion of thermistor  18  is inserted through the cut-out in bottom wall  20  and extends outside of control box  16 , and another portion resides inside control box  16 . The portion of thermistor  18  extending outside of control box  18  includes a sensing portion of thermistor  18 , and as such, thermistor  18  is able to obtain accurate temperature measurements of the outside ambient air. Because of its location extending out of a bottom of control box  16 , thermistor  18  is generally shielded from the sun and has minimal solar gain. 
       FIG. 2  is a perspective view of thermistor  18  from  FIGS. 1A-1C . In the exemplary embodiment shown in  FIG. 2 , thermistor  18  includes sensor portion  26 , shoulder  28 , base portion  30 , wires  22  extending from base portion  30 , and pair of ears  32  extending from sensor portion  26 . 
       FIG. 3  is a perspective top view of a portion of bottom wall  20  of control box  16  of  FIG. 1A  to illustrate mounting structure  34  including aperture or cut-out  36  and a pair of tabs  38 . Mounting structure  34  is configured for securing thermistor  18  to control box  16  such that sensor portion  26  of thermistor  18  is exposed to outside ambient air and thermistor  18  is immobile, yet under little or no strain. Bottom wall  20  includes top surface  20   a  and bottom surface  20   b  (not visible in  FIG. 3 ). 
     In the exemplary embodiment shown in  FIG. 3 , cut-out  36  includes generally circular portion  40 , a pair of oblong portions  42 , and a pair of L-shaped portions  44 . Each L-shaped portion  44  has short leg  44   a  and tall leg  44   b . Tabs  38  are each formed from a portion of wall  20  remaining inside and between L-shaped portions  44  and circular portion  40  and are defined by a bend or crease  46  formed in wall  20 . Tabs  38  are each bent downward extending away from bottom surface  20   b  of wall  20 . In preferred embodiments, tabs  38  are spring-like and resilient. In their natural position, tabs  38  are bent downward; however, if an upward force is applied to tabs  38 , tabs  38  are movable such that they are generally flush with wall  20 . Once a force is no longer exerted on tabs  38 , tabs  38  may return to their original downward-bent orientation. 
     Circular portion  40  of cut-out  36  is configured to receive sensor portion  26  of thermistor  18  and oblong portions  42  are configured to each receive one of ears  32  of sensor portion  26 . 
     In preferred embodiments, wall  20  of control box  16  may be formed from sheet metal. However, it is recognized that any other suitable material may also be used to form wall  20 . Mounting structure  34  may be formed in wall  20  using any metal cutting technique, including, but not limited to, stamping. In the embodiment of  FIG. 3 , a die may be used to punch out the features of cut-out  36 , and in a secondary operation using the same die, tabs  38  may be formed and bent downward. 
       FIG. 4  is a perspective top view of top surface  20   a  of wall  20 , including mounting structure  34  from  FIG. 3  (rotated counter-clockwise approximately 90 degrees), and thermistor  18  from  FIG. 2 .  FIG. 4  illustrates a step in the process of inserting thermistor  18  through cut-out  36 . Thermistor  18  may be placed above top surface  20   a  of wall  20  such that ears  32  of sensor portion  26  are aligned with oblong portions  42  of cut-out  36 . Sensor portion  26  including ears  32  are then received through cut-out  36  such that sensor portion  26  extends below bottom surface  20   b  (not shown in  FIG. 4 ) of wall  20 . In the exemplary embodiment shown in  FIGS. 1-4 , thermistor  18  and cut-out  36  are configured such that shoulder  28  of thermistor  18  is larger than circular portion  40 ; thus, shoulder  28  is unable to pass through cut-out  36 . Instead, shoulder  28  rests on top surface  20   a  of wall  20 . 
     Thermistor  18  may then be rotated 90 degrees in either direction by gripping and rotating base portion  30 . As thermistor  18  is rotated and ears  32  of sensor portion  26  pass under tabs  38 , ears  32  exert an upward force on resilient tabs  38 , thus pushing tabs  38  up towards wall  20 . Once thermistor  18  is rotated enough such that ears  32  are past tabs  38 , ears  32  will each be generally aligned with each short leg  44   a  of L-shaped portions  44 . Resilient tabs  38  then spring back to their original downward-bent position and lock ears  32  such that thermistor  18  is no longer able to rotate. Thermistor  18  is thus fixed within cut-out  36 . 
       FIG. 5  is a perspective view of bottom surface  20   b  of wall  20  with thermistor  18  and mounting structure  34 . As shown in  FIG. 5 , ears  32  of sensor portion  26  are aligned with short legs  44   a  of L-shaped portions  44  and tabs  38  are bent such that tabs  38  prevent movement by ears  32 . Rotation of thermistor  18  in either direction (i.e. clockwise or counterclockwise) is prevented because of the pair of tabs  38 . 
       FIG. 6  is another perspective view of thermistor  18  and mounting structure  34  of  FIG. 5 . As explained above and as illustrated in  FIG. 6 , because tabs  38  are bent downward and contact ears  32 , thermistor  18  is locked in place within bottom wall  20  of control box  16 . With the use of mounting structure  34 , fasteners are not needed to secure thermistor  18  within wall  20 . Thermistor  18  is easily mounted to wall  20  by inserting sensor portion  26  through cut-out  36  and then locking thermistor  18  in place with a quarter-turn twist (in either direction). Thermistor  18  is adequately fixed to wall  20  but is not under any strain. 
     Sensor portion  26  of thermistor  18  extends below bottom surface  20   b  of wall  20  of control box  16 . Sensor portion  26  is exposed to outside air, thus enabling thermistor  18  to provide an accurate ambient air temperature for efficient operation of condensing unit  10 . Moreover, because of its position extending from a bottom of control box  16 , sensor portion  26  is also shielded from any solar effects that may impact sensor portion  26  and its ability to provide an accurate temperature reading. 
     In the preferred embodiment of thermistor  18  and mounting structure  34 , as shown in  FIGS. 1-6 , thermistor  18  may be easily removed from mounting structure  34  if removal is necessary (i.e. for maintenance or replacement of thermistor  18 ). A small device, such as a screwdriver or knife, may be inserted between tab  38  and ear  32  (of  FIG. 6 ) to temporarily push tab  38  upward towards wall  20 . Thermistor  18  may then be rotated 90 degrees clockwise until ears  32  are aligned with oblong portions  42  and sensor portion  26  may be lifted back out through cut-out  36 . If the device were instead inserted between the opposite tab  38  and corresponding ear  32  (neither of which is visible in  FIG. 6 ), in that case, thermistor  18  may be rotated 90 degrees counter-clockwise in order to back thermistor  18  out of cut-out  36 . Thermistor  18  may be easily removed without any damage to itself or to mounting structure  34 . 
     The present invention relates to a mounting structure for a sensor or similar component. Although the present invention has been described above in relation to a thermistor for a control box of an outdoor condensing unit, it is recognized that the mounting structure could be used in various other applications where it is critical or desirable to easily mount a sensor or other small component without the use of additional fasteners. 
     Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.