Air conditioner with condensate slinging fan

An air conditioning system having a fan that moves air over the outside heat exchanger of the system. The fan is of the bladed axial flow type. A winglet projects curvilinearly both radially outward from the trailing end of the tip of each blade of the fan and perpendicularly upward from the blade pressure surface. A conduit directs condensate formed on and dripping from the system inside heat exchanger to a collector located under the fan. The blade winglets scoop condensate from the collector and draw the water inward toward the center of rotation of the fan, where air moving through the fan slings the water on to the outside heat exchanger.

BACKGROUND OF THE INVENTION 
This invention relates generally to air conditioning systems. More 
particularly the invention relates to an air conditioning system having an 
axial flow fan for moving air through a refrigerant condenser. 
Warm air is frequently also humid, i.e. it contains entrained water vapor. 
During operation of an air conditioning system in the cooling mode, the 
system refrigerant evaporator reduces the temperature of the air passing 
through it to below the dewpoint. In that condition, water vapor condenses 
on the evaporator. Some means must be provided to dispose of this 
condensate. In small unitary air conditioners, such as window or 
though-the-wall mounted room air conditioners, a common means to 
accomplish condensate disposal is by providing a condensate collection and 
drain path that communicates between the inside section and the outside 
section of the air conditioner. Condensate formed on the system evaporator 
drains into a collector in the inside section and then flows to a 
collector located under the condenser fan in the outside section. The 
outside section condensate collector and the condenser fan are arranged so 
that the fan will contact the condensate in the collector and sling it on 
to the hot surfaces of the system condenser where the condensate water 
evaporates. The arrangement is such that the fan will sling the condensate 
before the water in the collector rises to a level where it can overflow. 
A slinger arrangement eliminates the need for an inconvenient, unsightly 
and costly condensate drain from the air conditioner. There is another 
benefit from such an arrangement, in that the heat necessary to evaporate 
the water is taken from and thus assists in cooling the warm refrigerant 
in the condenser, resulting in an improvement in system efficiency. 
Some prior art designs provide condensate slinging capability in a fan by 
incorporating a shroud or ring as part of the fan. The shroud encircles 
the fan blades and attaches to each blade at its tip. The shroud contacts 
the water when the condensate reaches the design level, lifting the water 
into the moving air stream produced by the fan and causing the water to 
pass into the condenser. 
Condensate disposal arrangements using fans with slinger rings have certain 
design and performance shortcomings. Not all the water lifted from the 
condensate collector by the slinger ring is carried into the fan 
discharge. Some, in the form of droplets, is thrown radially outward until 
it impacts the system enclosure or other structural components. The impact 
of the droplets can cause annoying noise. Further, the condensate that 
does not spray upon the exterior of the condenser tubes is not available 
to increase the thermal efficiency of the system. Several prior art 
inventions have dealt with these problems by fitting stationary shrouds 
around the ringed fan. These stationary shrouds were configured to prevent 
the impingement of condensate droplets on other system structures and 
direct the droplets on to the condenser. Hence the configuration of the 
stationary shrouds were not able to be optimized for other considerations 
such as fan air flow efficiency and noise reduction. 
Encircling a fan with a rotating shroud or ring affixed to it also creates 
design and manufacturing difficulties, particularly when the fan is made 
of plastic in one piece. Since the shroud is at the region of maximum 
rotational velocity, the centrifugal force resulting from its weight is at 
a maximum for a given fan geometry, requiring that other portions of the 
fan be made to have the strength necessary to withstand the force 
generated by the shroud. This requirement may mean that the fan 
construction must be more robust than would otherwise be required. The 
junctions where the shroud meets and joins to the tips of the blades can 
be areas of weakness just where maximum strength is required. Plastic one 
piece fans are commonly manufactured using an injection molding process, 
with the point of plastic material injection into the fan mold being in 
the central or hub area. Achieving a good mold fill on a shrouded fan 
design can be difficult. In a molded plastic shrouded fan, a zone of 
reduced strength can be present in the shroud ring at a location 
equidistant or nearly so from adjacent fan blades because at that 
location, flows of plastic from opposite directions meet during the 
molding process but fail to meld and knit properly and completely. 
SUMMARY OF THE INVENTION 
The present invention is an air conditioning system having an axial flow 
condenser fan. The fan has a plurality of blades. Each blade has a slinger 
winglet protruding from the blade outer edge. The winglet extends out from 
a portion of the blade outer edge that is adjacent the blade trailing edge 
radially from the center of rotation of the fan. The winglet also extends 
outward from the pressure surface of the blade. The configuration of the 
winglet is such that when the tip of the blade enters the surface of 
water, the winglet scoops up water droplets and directs them radially 
inward toward the center of rotation of the fan and thus into the 
discharge air stream leaving the fan. 
The placement of a winglet on each blade of the fan is an improvement over 
a slinger ring or shroud encircling and affixed to the fan blades because 
it avoids the drawbacks associated with a shrouded configuration as 
discussed above and allows for a strong but lightweight fan even when 
fabricated from plastic.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIGS. 1 through 4 depict in detail one feature of the present invention, a 
blade of the condenser axial flow fan. Fan blade 10 is visible in all of 
the figures, while in one or more of the various views contained in the 
figures can be seen its leading edge 11, trailing edge 12, outer edge 13, 
pressure surface 14 and suction surface 15. A fan having fan blades 10 
rotates in direction D. 
Extending from the portion of outer edge 13 that is adjacent to trailing 
edge 12 is slinger winglet 21. Winglet 21 extends radially and 
curvilinearly to a maximum distance h from the main portion of outer edge 
13. Distance h is the difference between the maximum radius R swept by any 
point on leading edge 13 and the maximum radius R, swept by any point on 
winglet 21. Winglet 21 extends curvilinearly to a maximum distance d 
perpendicularly from pressure surface 14. In a plane perpendicular to 
pressure surface 14, winglet 21 has a generally "j" shaped cross section. 
In an optimum configuration for the winglet, both distance h and distance d 
should be about ten percent of radius R. The winglet should extend along 
approximately ten to 30 percent of the blade outer edge chord length, or, 
referring to FIG. 2, distance L' should be approximately ten to 30 percent 
of distance L. 
With fan blade 10 incorporated into an axial flow fan, the fan installed in 
the outside section of an air conditioning system as the condenser fan and 
with a condensate collector under the fan, as the system operates in a 
humid inside environment, condensate will collect under the evaporator in 
the inside section of the system and drain to the outside section 
condensate collector. As the water level in the condensate collector 
rises, the level will eventually reach a point where the rotating blades 
of the fan contact the condensate. Because it extends to a greater radius 
than the main body of the blade, the first part of blade 10 to come in 
contact with the water will be winglet 21. Winglet 21 scoops the water 
from the collector and draws it in toward the axis of rotation of the fan. 
As the water flows on to pressure surface 14, the air flow generated by 
the fan sweeps the water off fan blade 10 and carries it into the system 
condenser, where it is deposited on the heat transfer surfaces of the 
condenser, there to be evaporated and pass into the outside air flowing 
over the condenser. 
FIG. 5, in a partly broken away top plan view, depicts the major components 
of an air conditioning system embodying the present invention. Air 
conditioning system 50 has outside section refrigerant-to-air heat 
exchanger 51 and inside section refrigerant-to-air heat exchanger 52. When 
the system is operating in the cooling mode, heat exchanger 51 functions 
as a condenser and heat exchanger 52 functions as an evaporator. If the 
system is reversible, i.e. can operate as what is known in the industry as 
a heat pump, the functions of the two heat exchangers are reversed. Motor 
55 drives both inside fan 54 and outside fan 53. In the system 
illustrated, fan 54 is of the centrifugal or "squirrel cage" type and fan 
53 is of the axial flow type. An orificed stationary shroud 56 surrounds 
fan 53. Since slinger winglets 21 do not throw water droplets radially, 
shroud 56 may be configured for optimum air flow and reduction of noise 
rather than to control the flow of condensate water. 
FIG. 6 shows schematically the arrangement that directs the flow of 
condensate from heat exchanger 52 to a position where it can be picked up 
and directed on to the surface of heat exchanger 51 by fan 53. When 
condensate forms on heat ex=changer 52, it runs off that heat exchanger 
into inside collector and conduit 61. Conduit 61 directs the condensate to 
outside collector, that directs the flow of condensate into outside 
collector 62. Collector 62 is located beneath fan 53 in a position so that 
winglet 21 on a given blade 10 will extend into collector 62 when that 
blade is at its lowermost position during rotation. If the condensate 
level in collector 62 rises above a predetermined level, winglet 21 will 
contact the condensate water and sling it on to the surface of heat 
exchanger 51. Depending on the configuration and arrangement of system 50, 
inside collector and conduit 61 and outside collector 62 may need be no 
more than depressions stamped or molded in to the bottom of the enclosure 
for the system. 
The above discussion and description of the invention has focussed on its 
application to use in a unitary or window mounted room air conditioner. 
The invention may find its greatest utility in that application, but it 
may be used in many other applications where an axial flow fan is used to 
cause air movement through an air conditioning condenser as well.