Patent Application
20090226329
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.
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.
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
As the cooling fan 14 rotates, air enters into the pump housing 10 through the inlet opening(s) 13A and 13B. Air flow is represented by solid arrows in
Turning to
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
An improved float is also depicted in
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'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.
