Patent Publication Number: US-6699014-B1

Title: Quick connect device for ceiling fan blade and method therefor

Description:
FIELD OF THE INVENTION 
     This invention relates to a connecting device, more particularly to a connecting device for connecting a fan blade to a ceiling fan rotor. 
     BACKGROUND OF THE INVENTION 
     Ceiling fans have been popular for many years. However, conventional ceiling fans typically are not convenient to install. If the fan blades are not installed properly, the fans tend to vibrate and create a significant amount of noise. Referring to FIG. 1, a conventional ceiling fan  10  is shown to include an outer casing  12  for housing a motor  14 , a plurality of fan blades  16  (only one is shown), and a plurality of mounting arms  18  (only one is shown) for connecting the fan blades  16  to the bottom of the motor&#39;s rotor  20 . Each mounting arm  18  has two ends which are respectively secured on the corresponding fan blade  16  and the bottom of the rotor  20  by screw fasteners  22 ,  24 . 
     The use of screw fasteners  22 ,  24  tend to make if inconvenient to assemble the mounting arms  18 . Insufficient tightening of the screw fasteners  22 ,  24  can result in vibration of the mounting arms  18  and even discharge of the fan blades  16  from the rotor  20  during operation. Dynamic imbalance and vibration can even occur when screw fasteners  22 ,  24  are tight, but tightened in the wrong order. These variables can be frustrating for the do-it-yourself homeowner that simply wants to install a ceiling fan. 
     Recent fans have been designed to make it easier for the do-it-yourself installer. One such fan is disclosed in U.S. Pat. No. 6,095,753 to Hsu, and has a structure for mounting ceiling blades that does not require screws for attaching the blade to a ring mount on the rotor. The ring mount has a plurality of recesses having an inner end that gradually decreases in width toward an outer end. Each blade has a tongue that is configured so that its outer end is the same width as the outer end of a corresponding recess. The tongue inner end is also configured so that its width is the same size as the inner end of the corresponding recess. The blades slidingly connect to the rotor without the use of tools, and centrifugal force keeps the blades from being dislodged during operation. When the fan is not in motion, the blades can be removed by sliding each blade toward the inner end of a corresponding recess. While this is a convenient connection with respect to ease of assembly and disassembly, it requires exact tolerances for parts. If the tongue and recess do not fit together properly, then annoying and possibly dangerous blade vibration can occur. 
     Another such fan is disclosed in U.S. Pat. No. 5,980,353 to Wu. This fan also requires close tolerances so that the plug end of the blade does not vibrate with respect to the insert slot. Further, vibration can occur if each rotor mounting segment is not fastened properly to the motor or motor casing. 
     Accordingly, a need exists for ceiling fan having a simple attachment mechanism for attaching the fan blades to the rotor without using tools that can be manufactured without meeting exact tolerances. 
     SUMMARY OF THE INVENTION 
     The present invention comprises an impeller and blade assembly. A ring, including a plurality of dovetailed recesses that have a ceiling and two side walls is mounted onto the impeller. A biasing member such as a spring is secured to each recess&#39;s ceiling. Each fan blade is constructed from a wing connected to an arm, that has a dovetailed tongue corresponding to one of the recesses. Each tongue can be made to engage one of the dovetailed recesses without the use of a tool. The biasing member provides a bias between the tongue and recess sidewalls to prevent undue vibration therebetween. The biasing member or spring also locks the tongue into the recess to prevent accidental radial displacement. Thus, a tongue cannot move in a substantially radial direction with respect to the ring without applying pressure to the spring. The advantage of this invention is quick and easy installation, and increased safety and satisfaction due to reduced vibration. 
    
    
     While the present invention is particularly useful for ceiling fans, other applications are possible and references to use with ceiling fans should not be deemed to limit the application of the present invention. The present invention may be advantageously adapted for use where similar performance capabilities and characteristics are desired. These and other objects and advantages of the present invention will become apparent from the detailed description, claims, and accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial side elevational view of a prior art fan blade assembly; 
     FIG. 2 is a perspective view of a ceiling fan with a partially assembled blade attachment mechanism of an embodiment of the present invention; 
     FIG. 2A is a partial perspective view of the fully assembled blade attachment shown in FIG. 2; 
     FIG. 3 is a bottom side view of the fan blade bracket shown in FIG. 2; 
     FIG. 4 is a side elevational view of the fan blade bracket shown in FIG. 3; 
     FIG. 5 is a front elevational view of the fan blade bracket shown in FIG. 4; 
     FIG. 6 is a bottom side view of the ring portion of an embodiment of the present invention as shown in FIG. 2; 
     FIG. 7 is a side cross-sectional view taken at lines  7 — 7  in FIG. 6; 
     FIG. 8 is a side elevation of a spring of an embodiment of the present invention as shown in FIG. 2; 
     FIG. 9 is a plan view of the spring shown in FIG. 8; 
     FIG. 10 is a partial side elevational view of the ceiling fan shown in FIG. 2, with the ring portion as shown in FIG. 7; 
     FIG. 11 is a side elevational, partial cross-section of an optional motor housing adapter of an embodiment of the present invention; and 
     FIG. 12 is a plan view of the adapter shown in FIG.  11 . 
    
    
     DETAILED DESCRIPTION 
     The present invention provides, among other things, a new and improved ceiling fan including an attachment assembly for engaging fan blades with a rotating ring. The present invention is useful with all types of conventional fans. However, the invention is particularly useful for use with convention ceiling fans for permitting the easy installation of ceiling fan blades. 
     As shown in FIG. 2, a fan  40  has an impeller or rotor  42  including a plurality of fan blades  44  (only one shown) for displacing air. Each fan blade  44  is engaged to ring  46  by an attachment assembly or mechanism  48 . In this specific example, fan  40  is of a type commonly referred to as a ceiling fan with impeller or rotor  42  shown as it would appear in a decorative housing  50  and suspended for rotation from, for instance, a ceiling (not shown). In accordance with conventional practice, ring  46  may be rotated by a conventional electric motor or other suitable power source. 
     Referring now to FIG. 3, each fan blade  44  is generally comprised of a wing  45  connected to a connecting member such as an arm  47 . Such connection may be integral (i.e. a unitary molded piece, not shown) or may be accomplished with fasteners. Arm  47  has an elongate body  60  with a proximal end  62 , a distal end  64  and a tongue  68  carried by elongate body  60  adjacent proximal end  62 . Tongue  68  is configured so that it extends outwardly and upwardly from proximal end  62 , its inner end  70  gradually decreasing in width toward its outer end  72 . The upper surface of tongue  68  has a pair of substantially parallel grooves  74  extending between side is  76  and side  78 . As best seen on FIGS. 2 and 5, tongue  68  gradually increases in width as it extends upwardly from its bottom surface  80 . Thus, tongue  68  is “dovetailed” in both a vertical and horizontal direction. 
     A plurality of complementary engagement assemblies  90  of each attachment mechanism  48  are carried or otherwise supported by ring  46  at spaced radial intervals. Referring also to FIGS. 6 and 7, each complementary engagement assembly includes a recess  92  defined by sidewalls  94  and  96 , and ceiling  98 . Recess  92  extends into ring  46  for receiving tongue  68  of a selected one of fan blades  44 . As such, the outer end  102  of recess  92  is the same width as outer end  72  of tongue  68 , and the inner end  104  is the same width as inner end  70  of tongue  68 . Thus, recess  92  is “dovetailed” in both the vertical, and horizontal direction in the same fashion as recess  92 . Preferably, the tolerance between tongue  68  and recess  92  is a slip fit. 
     Referring to FIGS. 2 and 6, a spring  110  is mounted in recess  92  for providing a bias against tongue  68  after the fan is assembled; the spring  110  biases the tongue  68  against at least one of the side walls defining the recess. Such bias prevents undue vibration due to the tolerances between tongue  68  and recess  92 . The spring  110  also serve to selectively lock the tongue  68  into recess. Preferably, spring  110  is constructed from a spring steel or metals having similar qualities. Spring  110  may have various configurations that fit against tongue  68 ; only one possible embodiment is depicted. Regardless of the exact configuration, it is preferable that spring  110  have three ridges thereon: a stop  112 , a mid-ridge  114  and an end-ridge  116 . Between end ridge  116  and mid-ridge  114  is a flat section  118  with an aperture  120  for the purpose of mounting spring  110  to the ceiling  98  of ring  46 . Also, between mid-ridge  114  and stop  112  is a second flat portion  124 . The purpose of stop  112  is to prevent tongue  68  from accidentally moving toward the rotational axis  119  of the fan, see FIG.  10 . Mid-ridge  114  and end-ridge  116  are configured to engage grooves  74  in tongue  68 . Spring  110  has enough stiffness whereby the sides  76 ,  78  of tongue  68  are pressed firmly against sides  94 ,  96  of recess  92 . As a result, when the fan is in operation, there is negligible vibration between tongue  68  and recess  92 , and little or no unwanted noise. 
     Ring  46 , preferably, is made from a die-cast zinc alloy or of metals with similar properties and is shown in detail in FIGS. 6 and 7. As mentioned previously, ring  46  has a plurality of recesses  92 , which are preferably spaced evenly apart to prevent a dynamic imbalance during fan operation. 
     In a more preferred embodiment of the present invention, the recess ceiling  98  is not flat as shown in FIG. 2, but instead has a secondary recess  140  for seating spring  110 . Recess  140  is substantially centrally located on ceiling  98 , and has a mount  142 , and fastener  128  to accommodate spring flat portion  118 , and a stop pad  144  to limit movement of stop  112  when spring  110  is flexed. The width of secondary recess  140  matches that of spring  110 , and has a tolerance that allows spring flexure. Ring  46  also has a plurality of evenly spaced apertures  130  to accommodate fasteners for attachment to motor housing  50 . 
     An optional motor housing adapter  150  is shown in FIGS. 10 through 12. In cases where the arm  27 , spring  110 , ring  46  are sold as a kit to ceiling fan manufacturers, the adapter  150  similar to that shown may be necessary to for fitting the ring  46  to a stock motor housing  50 . This adapter  150  may replace the lower portion of a stock motor housing  50  (see FIG.  2 ). Adapter  150  may be manufactured from a stamped or die-cast metal, and is generally constructed from two pieces, a main body  152  and an inner cap  154 . The two pieces are preferably connected by rivets or spot welds (neither shown). Apertures  156  are evenly distributed on the adapter  150  for mounting it to the stock housing  50 . Apertures  158  are located on the adapter so that they correspond to apertures  130  on ring  46 . Fasteners  160  are used to connect ring  46  to adapter  150  as seen in FIG. 2 (or alternatively, directly to a stock motor housing  50  as seen in FIG. 2A.) Adapter  150  may include a center aperture  162  to accommodate a light fixture (not shown). 
     Preferably, the ceiling fan is shipped to the consumer so that no tools are required for assembly. For instance, the ring  46  may be already be connected to rotor  42  and arm  47  already connected to wing  45 . The spring  110  may already be connected to ring  46 , preferably with a locking-type fastener. In such case, assembly by the consumer, a selected one of fan blades  44  may be grasped and tongue  68  directed toward one of the recesses  92  as shown substantially in FIG.  2 . Each tongue  68  is introduced into a corresponding recess  92  in the direction generally indicated by arrow B in FIG. 6, which can be described as a radial direction with respect to ring  46 . As tongue  68  is urged into recess  92 , it will abut against sidewalls  94  and  96  and overcome the bias of compression spring  110 . Tongue  68  will snap into place once mid-ridge  114  and end-ridge  116  of spring  110  are aligned with tongue grooves  74 . The “snap” generally occurs when the stop on the spring moves from a flexed position to a non-flexed position. FIG. 2A shows tongue  68  assembled with ring  46 . For disassembly, spring stop  112  is pushed toward the motor housing  50  in a direction substantially parallel to the rotational axis  119  (see FIG.  10 ), and the tongue  68  is pulled out of recess  92  in the direction opposite from which it was inserted. 
     Existing ceiling fans may be retrofitted with the present invention. For example, a kit may be provided for such purposes, the kit including the biasing member or spring  110 , the ring  46  adapted to engage an existing fan impeller or rotor  42 , and a fan blade arm  45  having a tongue  68  at one end. The tongue  68  is configured to fit into the recess  98  and against the spring  110  when assembled with the ring  46 . 
     In summary, the present invention provides an attachment mechanism for detachably engaging fan blades with a rotating ring of, for instance, a ceiling fan without the use of tools. Although the invention has been herein shown and described in what is perceived to be the most practical and preferred embodiments, it is to be understood that the invention is not intended to be limited to the specific embodiments set forth above. Accordingly, it is recognized that modifications may be made by one skilled in the art of the invention without departing from the spirit or intent of the invention and therefore, the invention is to be taken as including all reasonable equivalents to the subject matter of the appended claims.