Abstract:
An electric fan assembly has structurally independent motor driven blades module, stand and shaft. The module and stand are mechanically assembled together by two mounting rings that are captured on the shaft. Electrical connections are also made during mechanical assembly with mateable connectors on internal cords.

Description:
TECHNICAL FIELD 
     This invention relates generally to electric fans, and more specifically to self standing electric fans that are packaged and sold in multiple units for later assembly. 
     BACKGROUND OF THE INVENTION 
     Self standing electric fans usually have motor driven fan blades mounted atop a pole or shaft that extends uprightly from a base or stand. Most of these have the motor driven fan blades constructed as a module that oscillates to distribute their air flow. Some have the module mounted to the shaft about four feet above the floor. Others have telescoping shafts so that the height of the blades module may be varied. Due to their length, especially those whose height is fixed, it is impractical to package, ship, store and sell these fans in a fully assembled configuration. Accordingly, they have often been designed, packaged and distributed in a broken-down configuration. 
     Heretofore, such self standing fans have been segmented for packaging into three discrete units, namely into a blades and motor module, a shaft and a base. This has been done by telescopically mounting the module and base to opposite ends of the shaft or pole with a tab and notch. Electric power is provided with an electric cord that extends from the module to an electric outlet as on a nearby wall. 
     The just described multi-unit, self standing fans have had certain pronounced problems. Foremost among these has been the electric cord that is draped from the fan motor. Not only has it been visually displeasing, but it has presented a trip hazard. It also has wiggled or bent back and forth somewhat as the fan oscillates. Attempts at extending the cord through the shaft have been impeded by UL safety regulations where the stand is collapsible since the cord gathers and extends inside the shaft. Also, running the cord through the shaft and base requires excessively large ports to accommodate the plug at the cord end. 
     Accordingly, it is seen that a need exists for a self standing electric fan assembly and fan assembly method that alleviates the just described problems. It is to the provision of such that the present invention is primarily directed. 
     SUMMARY OF THE INVENTION 
     In a preferred form of the invention an electric fan assembly comprises a stand having a base from which a leg upwardly extends that bears external threads and a leg electrical connector mounted adjacent the top of the leg from which electrical conductors extend. Fan blades coupled with an electric motor are mounted upon a hollow shaft from which motor upper electric conductors extend through the shaft to an upper connector configured to be releasibly connected with said base leg connector; and a mounting ring slidably mounted about the shaft that bears internal threads sized to be threaded onto the stand leg threads in releasibly mounting the shaft to the base. 
     In another preferred form of the invention an electric fan assembly comprises a stand bearing mounting threads and a subassembly bearing mounting threads that has a plurality of fan blades coupled with an electric motor. The assembly has a hollow rod to opposite ends of which the stand and the subassembly may be detachably mounted. Two mounting collars are slidably mounted to the rod that bear threads sized to be threaded upon the stand threads and the subassembly threads in securely mounting the subassembly and stand to the rod. 
     In yet another preferred form of the invention a method is provided for assembling a self standing electric fan that has a base with an electric connector from which a base cord extends, a hollow shaft, and an electric motor driven blade module from which an electric motor cord extends to a module connector. The method comprises the steps of passing the motor cord through the shaft, connecting the motor cord with the base cord, mounting the fan blade module to one end of the shaft, and mounting the base to the other end of the shaft. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  is an exploded view, in perspective, of a self standing fan assembly that embodies principles of the invention in a preferred form. 
         FIG. 2  is an enlarged view of an upper portion of the fan assembly. 
         FIG. 3  is an enlarged view of a lower portion of the fan assembly. 
         FIG. 4  is a cross-sectional view of part of the lower portion shown in  FIG. 3  but shown in an assembled configuration. 
     
    
    
     DETAILED DESCRIPTION 
     With reference now in more detail to the drawing there is shown an electric fan assembly  10  that has a set of fan blades  11  mounted within a protective grill  12  that are rotatably driven by an electric motor shown generally at  13  in a conventional manner. Preferably the fan blade and motor module  14  is oscillatory although it need not be. The module is supported above a floor or the like by a decorative hollow, cylindrical shaft or pole  15  and base or stand  16 . As best shown in  FIG. 1 , the fan assembly can be configured in a broken down configuration for packaging, shipping and storage into its three distinct units, namely its motor driven blades module  14 , its shaft  15  and its base  16 . For use it is easily reconfigured into an assembled configuration as hereafter described. 
     The shaft  15  is packaged with two mounting collars or rings  20  slidably mounted on the shaft. These are mounted trapped or captured between end flanges  19  of the shaft  15  so that they cannot come off the shaft. As best shown in  FIG. 4 , each mounting collar  20  has one side  23  that has an inside diameter smaller than the outside maximum diameter of the shaft flanges  19  and another side  24  that has a threaded inside surface of an inside diameter greater than the maximum outside diameter of the shaft flanges  19 . The two collars  20  are mounted to the shaft in opposite orientations so that their sides  23  are adjacent to one another. These sides  23  are each seen to have two annular inside grooves in which two O-rings  25  are seated flushly against the shaft  15 . 
     Both the motor driven blades module  14  and the base  16  are seen to have two cylindrical necks  26  and  27 , respectively, that bear external threads  28  and  29 . These threads are located at some distance from the ends of the necks. As shown in  FIG. 2 , the neck  26  is formed with a raised tab  30  to mate with a notch  31  in the top flange  19  of the shaft. This is done as a means of locating the blades module with respect to the base which also has this type of tab feature. Finally it should be noted that the module neck  26  does not oscillate but supports a bearing  33  on which the rest of the module may oscillate. 
     An electric cord  36  extends from the motor  13  down through the module neck  26  and shaft  15  and is terminated at its bottom end with a male connector  38 . Another electric cord  40  that is formed with a plug  41  at one end extends into the base  16  to a female connector  43  to which the connector  38  may be conventionally connected. Whereas the connector  38  is flexible, it being at the end of cord  36  that extends freely through the shaft  15 , the connector  43  here is stationarily mounted atop the base neck  27 . 
     As previously stated, the fan assembly may be packaged, transported, stored and sold in its broken down configuration for compactness. To assemble it the motor cord  36  is passed through the shaft  15  and connected with the base cord  40  by inserting connector  38  into connector  43 . In doing this the blades module neck  26  is inserted into the top end of the shaft  15 . After the connectors  38  and  43  are joined the base neck  27  is inserted into the bottom of the shaft. All this is facilitated by the cord  36  with its connector  38  being flexible and the base connector  43  inflexible whereby the connector  38  may be gripped and aligned with the connector  43  while the connector  43  remains put. As the assembly base and shaft are brought together the cord  38  is free to flex inside the shaft. The sequence of these just described assembly steps may of course be varied. 
     Once the blades module and base have been mounted to the shaft the assembly may be set upright. The two mounting collars may then be slid partially over the shaft flanges and then screwed onto the module thread  28  and the base threads  29  until tight and secure fits are made. In sliding the collars their O-rings prevent the decorative exterior surface of the shaft from marring. 
     It thus is seen that a self standing electric fan assembly and fan assembly method are now provided that alleviate problems associated with those of the past. The assembly is of simple and economic construction. Its method of assembly could hardly be easier. 
     Although the invention has been shown and described in its preferred form, it should be understood that many modifications may be made thereto without departure from its spirit and scope as set forth in the following claims.