Patent Publication Number: US-2009226329-A1

Title: Condensate Pump

Description:
FIELD OF THE INVENTION 
     This invention relates to an improved condensate pump that employs a fan and volute casing to expel air surrounding a pump motor to provide an improved cooling effect. 
     BACKGROUND OF THE INVENTION 
     Condensate may be produced in an HVAC (heating or cooling) or refrigeration system. Some examples include high-efficiency furnaces, which extract so much heat from exhaust gases that water vapor in the exhaust condenses, or air conditioning units, where condensate is produced when moist air contacts cold evaporator coils. It is known to provide a condensate pump to discharge the condensate produced in these systems. Condensate generated from latent water vapor must be collected and discarded to avoid damage to the heating/cooling unit and to prevent this contaminant from entering the surrounding environment. 
     Condensate pumps are typically centrifugal pumps, which consist of a set of rotating vanes, enclosed within a housing or casing and used to impart energy to a fluid through centrifugal force. An impeller contained within a volute casing at the bottom of the pump provides necessary pumping action of the condensate pump. This impeller is usually connected to an electric motor via a shaft that extends downwards from the motor, which is mounted above the tank where the condensate accumulates. The condensate fluid to be pumped passes along a flow path extending from a central inlet to the impeller, whereby the fluid is expelled at a high rate centrifugally outward against the surrounding casing which opens to a volute throat leading to a pump discharge outlet. 
     The electric motor of a condensate pump needs to be cooled during operation. Most pumps use a fan mounted above the motor to effect an air current directioned to cool the motor. One type of cooling system for a condensate pump motor is known from U.S. Pat. No. 6,322,326 (Davis et al.). In that device, the modular condensate pump assembly employs a turbine air fan supported on an upper end of a drive shaft. The cover surrounding the fan contains a plurality of air inlet slots at a base of the cover, and a plurality of long, vertical air outlet slots on each of three sides of the cover, to facilitate air ventilation and cool the electric motor. While the warmed air is expelled on three sides of the cover containing air outlet slots, this exiting air flow is somewhat random. Thus one must reduce the power output of the motor, and thus reduce the output of the pump, in order not to decrease motor life. 
     The condensate pump motor is often triggered automatically by a main float disposed in the tank, where condensate liquid is collected. Davis et al. discloses a float in the collection tank of a condensate pump that provides a two position mechanical level control. When condensate reaches an upper level in the tank, the float rises to a first start position to engage a micro-switch, thereby activating the motor to discharge the liquid. When the condensate subsequently returns below a lower level, the float falls to a stop position, triggering the micro-switch again, this time to deactivate the motor. Since this float is only activated when condensate reaches a specified upper level, a user will be unable to expel condensate at an earlier time. An option of activating the float prior to condensate reaching the specified upper level may be useful to test the operability of the float, or to simply pump out remaining contents in the collection tank. 
     Thus, there is a need for a condensate pump that provides a ventilation system that more efficiently expels the warm air surrounding the pump motor. In addition, there is a need for a main float that is accessible from outside the pump housing, such that a user may directly engage the switch and activate the pump motor at any time. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a perspective view of a condensate pump and a partial cutaway perspective view of the pump housing, in accordance with the present invention. 
         FIG. 2  illustrates a cross-sectional top view of the condensate pump of  FIG. 1 . 
         FIG. 3  illustrates a perspective cross-sectional bottom view of the condensate pump of  FIG. 1 . 
         FIG. 4  illustrates a perspective, exploded view of all components contained within the condensate pump of  FIG. 1 . 
         FIG. 5  illustrates a perspective view of an improved float, in accordance with the present invention. 
         FIG. 6A  illustrates a front view of a manual float activation device of the float of  FIG. 5 . before the float is raised. 
         FIG. 6B  illustrates a front view of a manual float activation device of the float of  FIG. 5 . after the float is raised. 
     
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
     While this invention is susceptible to embodiments in many different forms, there is shown in the drawings and will herein be described in detail, a preferred embodiment of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiment illustrated. 
     Referring to the drawings in general, and in particular to  FIG. 1 , shown therein is an improved condensate pump  9 . The condensate pump includes a pump housing  10  supported on a collection tank  11 . The pump housing  10  includes an upwardly extending cover  12 . The cover  12  includes inlet opening(s)  13 A and  13 B, which are preferably positioned on side walls of the cover  12  and at the base of the cover  12 , respectively. The cover  12  encloses several components, including a cooling fan  14  and a motor  15 . The cooling fan  14  is supported and driven by a shaft  16  ( FIG. 4 ), which is driven by the motor  15 . The collection tank  11  is used to collect condensate liquid. 
     As the cooling fan  14  rotates, air enters into the pump housing  10  through the inlet opening(s)  13 A and  13 B. Air flow is represented by solid arrows in  FIGS. 1-3 . While air flow in most of the inlet opening(s)  13 A are directioned inward (i.e. toward the inside of the cover  12 ), air flow in those inlet opening(s)  13 A furthest from the fan  14  may be more random—directioned both inward and outward. The cooling fan  14 , when rotated by the motor  15 , creates a low-pressure area that causes air to be drawn into the pump housing  10 . Specifically, the rotating fan  14  draws the air through inlet opening(s)  13 A and  13 B, into the center of the fan  14 , and then pushes the air out in a radial and tangential direction by a centrifugal force. Also, the air surrounding the motor  15 , which has been warmed due to the operation of the motor  15 , is similarly drawn into the fan  14  and then spun out. 
     Turning to  FIGS. 2 and 3 , an inner circular portion  20  is a part of the cover  12  that is shaped around the fan  14 . The interior circular portion  20  is sized to fit right around the fan  14 , such that it has an inner radius that is only slightly greater than the radius of the fan  14 . Preferably, the inner circular portion  20  is shaped around at least 90 degrees of the fan  14 . A throat  21  is typically a nozzle portion of the cover  12 , and located on the opposite side of the fan  14  as the inlet opening(s)  13 A. The throat  21  is the space defined between an exhaust opening  22  and a discharge outlet  23 . The exhaust opening  22  is the entrance to the throat  21 . The discharge outlet  23  is angled relative to the walls of the cover  12  that define the throat  21 . A cutwater  24  is adjacent to the exhaust opening  22 , and is the wall that divides the throat  21  from the inner circular portion  20 . Thus, the cutwater  24  defines an end of the inner circular portion  20 . The cutwater  24  is a design feature typically found in the volute casing of a centrifugal pump, where it is referred to as either the “cutwater” or the “tongue of the volute.” 
     Once the air is pushed out of the fan  14  with a certain velocity, its kinetic energy is converted to pressure energy by means of the resistance to air flow provided by the cover  12 . The part of the cover  12  that is most responsible for this energy conversion is the inner circular portion  20 . The inner circular portion  20  functions as a volute casing and is responsible for efficiently directing air flow and subsequently expelling it. Air flow is expelled by being directed towards the exhaust opening  22 , through the throat  21 , and then exiting through the discharge outlet  23 . Due to the conversion into pressure energy, and the lower pressure environment within the open space provided by the throat  21 , air exits rapidly through the discharge outlet  23 . 
     As depicted in  FIG. 4 , the motor  15  is attached to the motor plate  30 . The shaft  16  extends from the motor  15  and through the motor plate  30 . An impeller  31  is disposed inside a volute casing  32 , which is contained inside the collection tank  11 . The volute casing  32  is removably connectable to the motor plate  30  via at least one hook  33 , which is inserted and attaches to at least one slit  34  on the motor plate  30 . Preferably there are two or more hooks  33  that attach to corresponding slits  34  on opposite sides of the motor plate  30  to adequately support the volute casing  32 . The upper end of the shaft  16  supports and drives the fan  14 , while the lower end of the shaft  16  supports and drives the impeller  31  that expels the stored condensate liquid. 
     An improved float is also depicted in  FIG. 4 , and in greater detail in  FIGS. 5 and 6 . A float  40  ( FIG. 5 ) is disposed in the collection tank  11 . The float  40  is attached to one end of a removably connectable float arm  41  ( FIG. 5 ), and a tab  42  is attached to the other end of the float arm  41 . The tab  42  extends outside the pump housing  10 . The float arm  41 , which pivots about pivot point  43 , has an attached extension  44  with a slot  45 . The operating switch lever  46 , passes through the slot  45  on one end, and is attached to an operating switch  47  on the other end. The operating switch  47  has an operating switch button  48  ( FIGS. 6A and 6B ), when pushed upwards, activates the motor  15 . The float arm  41  is attached to the condensate pump by a fastener  49  that passes through the pivot point  43 . 
     The float  40  communicates with the motor  15  such that when the float  40  is raised it activates the motor  15 . The float  40  may be raised automatically when the condensate liquid reaches an upper level in the collection tank  11 , or may be raised manually by pushing tab  42 . Either way, when the float  40  is raised, the attached extension  44  with slot  45  is simultaneously raised, which in turn lifts the operating switch lever  46 . When the operating switch lever  46  is raised, the operating switch button  48  is pushed upwards, thereby triggering the operating switch  47  and activating the motor  15 . So, the float  40  provides a manual float activation device so that a user can manually activate the motor  15  before the condensate reaches the upper level. This allows the user to test the pump&#39;s operability, or to empty out the contents of the collection tank  11  at any given time. 
     While specific embodiments have been illustrated and described, numerous modifications may come to mind without significantly departing from the spirit of the invention, and the scope of protection is only limited by the scope of the accompanying claims.