Abstract:
A window fan assembly comprising a housing with openings therein for an air stream through the housing; at least one fan is mounted in the housing for generating the air stream through the openings of the housing; and a sensor connected to the housing, the sensor being disposed on the housing for detecting moisture particles associated with the air stream, upon the detection of a moisture particle of a predetermined size, the sensor causes an interruption of the air stream by stopping the fan operation.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to window fans, and, in particular, relates to devices for controlling the fan during inclement weather, especially during rain. 
     2. Brief Description of Related Developments 
     During raining weather, rain whether wind blown or otherwise may enter through a window having a window fan therein. 
     Thus, there exists a need for controlling the action of a window fan under inclement conditions. 
     SUMMARY OF THE INVENTION 
     In accordance with a first embodiment of the present invention a window fan assembly is provided. The window fan assembly comprises a housing with openings therein for an air stream through the housing. At least one fan is mounted in the housing for generating the air stream through the openings of the housing and a sensor is connected to the housing for detecting moisture particles associated with the air stream and upon the detection of a moisture particle of a predetermined size, the sensor causes interruption of the air stream by stopping the fan operation. 
     In accordance with a method of the present invention, a method is provided for controlling the fan operation in the present of moisture particles. The window fan has at least one fan in a housing with openings therein for an air stream during fan operation. A sensor is mounted in the window fan housing in close proximity to the openings for the air stream for sensing the presence of moisture particles therein. The sensor has a sensor circuit to control the fan operation by a sensor element having two separated conductive grid works, the grid works being separated by a predetermined distance. In the presence of moisture particles of a predetermined size, the sensor circuit interrupts fan operation to prevent the air stream from carrying the moisture particles through the fan housing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing aspects and other features of the present invention are explained in the following description, taken in connection with the accompanying drawings, wherein: 
     FIG. 1 is an elevation view of the window fan incorporating features of the present invention; 
     FIG. 2A is a perspective view of a rain sensor device of the window fan of FIG. 1; 
     FIG. 2B is a perspective view of another embodiment of a rain sensor element of the window fan in FIG. 1; 
     FIG. 3 is a partial cross sectional side view of the rain sensor device of the present invention mounted in a front wall of the housing of the window fan of FIG. 1; and 
     FIG. 4 is a schematic diagram of the circuit used to control the window fan of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, there is shown a front view of a window fan  10  incorporating features of the present invention. Although the present invention will be described with reference to the embodiment shown in the drawings, it should be understood that the present invention could be embodied in many alternate forms of embodiments. In addition, any suitable size, shape or type of elements or materials could be used. 
     As shown in FIG. 1, the window fan  10  generally comprises a window fan with a housing designed and configured to fit within a window opening with one or more fan openings in the front and back walls. The fan section comprises a fan motor mounted in the housing with a fan blade thereon. The fan motor is controlled by a fan circuit providing one or more of the following features: controls to turn the fan motor on or off, change direction of the motor, or change the speed of the motor and a rain sensor device for controlling the fan motor in the presence of precipitation mounted to the front wall of the window fan housing. The rain sensor circuit has a controller for turning off power to the fan motor upon at least one raindrop contacting a grid work of conductive material; otherwise, the rain sensor circuit does not affect the electrical power to the fan motor. 
     Referring to FIG. 1, a window fan  10  is shown by front view having a housing  12  of essentially rectangular configuration and made of plastic, metal or a combination of either. The housing  12  may have other configurations that are equally suitable, but FIG. 1 shows the housing  12  with a front wall  14 . The back, sides, top and bottom walls are not shown. In the preferred embodiment, a pair of fan motors  66 , FIG. 4, is mounted to the housing  12  with fan blades  16 , mounted to the fan motors  66 . In alternative embodiments, there may be any number of fans in the housing. For further controlling the flow of air, a rotating grill  18 , for example, is mounted to the back wall. Adjustable accordion spacers  20  are mounted on the side walls for properly fitting the window fan  10  in the window opening, not shown. A rain sensor device  24  is positioned and mounted in the window fan  10 . An appropriate line cord  26  is mounted to the housing  12  and provides power to the fan motors  66  and the rain sensor device  24 . 
     The rain sensor device  24 , FIG. 3, is shown in a cross-sectional side view mounted to the front wall  14  and facing to the outside of the window in the preferred embodiment. In this position, the rain sensor device  24  may be exposed to wind driven rain or to some of the rain that is being drawn into a fan opening  17 . The rain sensor device  24  is generally mounted centered between the fan openings  17 . In this location, the rain sensor device  24  may sense rain drops which may be drawn/enter in the fan opening  17 . In alternative embodiments, the sensor device  24  may be mounted in any other location. A rain sensor housing  28  forming a partially enclosed space is attached to the front wall  14  by tack welding, for example, around a mounting flange  30 . A rain sensor element  32 , FIG. 2A, of the rain sensor device  24  is mounted to be protected from non-wind blown rain. The rain sensor element  32  is mounted to a rain sensor housing rear wall  34  which is slanted at an angle Θ between about 45 and 60 degrees from the horizontal line  36 . In alternative embodiments, another suitable angle between 0 to 90 degrees may be used. This protects the rain sensor element  32  from raindrops falling vertically and/or when no rain is being drawn into the window fan  10  such as when the window fan  10  is in the exhaust mode. 
     Alternative locations for the rain sensor device  24  may be directly under the fan opening  17  on the front wall  14  or within the fan housing  12  under the fan  16 . The configuration of the rain sensor device  24  as will be described in greater detail below may vary as desired to suit the location of the rain sensor on the housing. 
     The rain sensor element  32 , FIG. 2A, has a mount housing  38  with mounting flanges  40  that are mounted to the rain sensor housing rear wall  34 . The mount housing  38  has a rain drain  42  on a lower edge  44  which allows any excess water to flow from the rain sensor element  32 . This drain  42  insures that if the rain has stopped, a grid work  46 , FIG. 2A, will immediately start drying. 
     The grid work  46  has a lower electrically conductive wire grid  48  with wires crisscrossing in a substantially rectangular pattern although other patterns may be used. An upper electrically conductive wire grid  50  is similarly constructed and is mounted in essentially parallel relationship to the lower grid  48 . The crisscrossing wires present a pattern with intersecting points  52  positioned respectively in the lower and upper grids  48  and  50 , above each other. The lower and upper grids  48  and  50 , respectively, are separated by a predetermined distance of approximately {fraction (1/16)} inch in the preferred embodiment, this being about the diameter of a rain drop  54 . Thus, as rain drop  54  falls through the grid work  46 , it will make an electrical contact between the lower and upper grids  48  and  50 , respectively. The lower and upper grids  48  and  50  are separated by an insulating plate  56  having a plurality of essentially vertical channels  58  therethrough. The diameter of each channel  58  is approximately ¼ inch but other dimensions are possible and would make the grid work  46  more sensitive if a larger diameter is used. The intersecting points  52  of the wire grids are positioned substantially in the center of the channels  58  so that as the drop falls through the channel  58 , contact will be made therewith. Electrical wires are connected to the lower and upper grids  48  and  50 , respectively as will be described below. 
     FIG. 2B illustrates an alternative embodiment of a sensor element  80 . Upon an insulating substrate  96 , a first conductive area or track  82  is formed having a plurality of finger-like strips  88 A. A second conductive area or track  84  is also formed on the insulative substrate  96  and also has a plurality of finger-like strips  88 B. The area where the finger-like strips  88 A,  88 B of the areas  82  and  84  interface is defined as an interdigitating area  86  where each finger  88 A,  88 B is separated from the adjacent finger by an insulating strip  90  running therebetween. The width of the insulating strip  90  determines the reactivity of the sensor  80  to rain water. In addition to being electrically insulating, the strip  90  may further be composed of a material which is hydrophobic to water thus insuring that the strip  90  does not remain wet after the raindrop ha s fallen off. The electrical circuit connected to the sensor  80  by wires  92 ,  94  is detailed below. 
     If the rain sensor element  32  is located on the housing  12  so that rain carried by the intake air stream whether wind driven or fan drawn will fall on the grid work  46 . As noted before, in the event that this rain sensor location is such that the sensor is not directly subject to rain, the grid network may be changed as a result since smaller water drops or mist may be used to activate the grid work  46 . 
     Referring to FIG. 4, an electrical schematic diagram is shown for operating the window fan  10  with the rain sensor element  32  therein. 
     The rain sensor element  32  has its lower and upper grids  48  and  50 , respectively, connected to wires  60  and  62 . In its normal electrical state, the rain sensor is an open circuit, but when a raindrop contacts both the lower and upper grids  48  and  50 , respectively, the circuit is closed. A manual override switch  64 , normally closed, may be used to override the short condition and restart the fan motor(s)  66  if the rain has stopped and the fan motors have not turned on immediately or the operator wants to reverse the direction of the fan  16  to the exhaust mode from the intake mode during rain. The sensor wires  60  and  62  are connected to a controller  68  which may have a relay, normally closed, to provide line power to the fan circuit  70 . For example, upon rain, the rain sensor element  32 , changing to closed circuit, will cause the relay to open which removes the line power from the fan circuit  70 . The lower voltage power is provided to the sensor circuit  72  by a transformer circuit  74 . A fan reverse switch  75  is connected in each fan circuit as well as one or more speed control devices  76 , one for each fan motor, although one is clearly possible. 
     It should be understood that the foregoing description is only illustrative of the invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances that fall within the scope of the appended claims.