Patent Publication Number: US-6213717-B1

Title: Balancing ring for a ceiling fan

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a ceiling fan, more particularly to a balancing ring for a ceiling fan. 
     2. Description of the Related Art 
     Referring to FIG. 1, in order to maintain balance and prevent swaying of a ceiling fan  1  when the latter operates, it is known in the art to provide a weight  4  on a top surface  3  of each fan blade  2  of the fan  1 . The weight  4  is generally secured on the respective blade  2  with the use of a double-sided adhesive tape  5 . However, it is noted that untimely removal of the weights  4  easily occurs when the blades  2  rotate at a relatively fast speed. In addition, proper installation of the weights  4  cannot be performed without the presence of a skilled technician. 
     SUMMARY OF THE INVENTION 
     Therefore, the object of the present invention is to provide a balancing ring, which can be easily and securely installed on a ceiling fan, to maintain balance and prevent swaying of the fan when the latter operates. 
     According to this invention, a balancing ring comprises a ring member, a plurality of metal balls, a ball restraining ring, and lifting means. 
     The ring member has a top side, a bottom side, an inner peripheral wall that confines a central opening, an outer peripheral wall, and an annular groove formed in the top side between the inner and outer peripheral walls. The groove has a groove bottom formed with an annular ball receiving recess. 
     The metal balls are disposed in the ball receiving recess. 
     The ball restraining ring is disposed in the groove above the groove bottom, and is movable inside the groove in at least an axial direction of the central opening between a restricting position, where the metal balls are restricted from moving freely, and a releasing position, where the metal balls are free to move in the ball receiving recess. 
     The lifting means, which is provided in the groove, permits movement of the ball restraining ring in the groove in response to rotating speed of the balancing ring. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments with reference to the accompanying drawings, of which: 
     FIG. 1 is a perspective view illustrating how a ceiling fan is balanced in a conventional manner; 
     FIG. 2 is a perspective view illustrating the first preferred embodiment of a balancing ring according to the present invention when applied to a ceiling fan; 
     FIG. 3 is an exploded perspective view of the first preferred embodiment; 
     FIG. 4 is an assembled cross-sectional view of the first preferred embodiment; 
     FIG. 5 is a schematic top view illustrating the balancing effect of the first preferred embodiment; 
     FIG. 6 is an exploded perspective view of the second preferred embodiment of a balancing ring according to the present invention; 
     FIG. 7 is an assembled cross-sectional view of the second preferred embodiment; and 
     FIG. 8 is a schematic top view illustrating the balancing effect of the second preferred embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIGS. 2 and 3, the first preferred embodiment of a balancing ring according to the present invention is shown to be mounted securely on a rotatable portion, such as a rotor, of a ceiling fan  10 . The balancing ring includes a ring member  20 , a ball restraining ring  30  and a cover member  40 . 
     With further reference to FIG. 4, the ring member  20  has a top side  200 , a bottom side  201 , an inner peripheral wall  202  that confines a central opening  21 , and an outer peripheral wall  203 . An annular flange  210  projects radially from the inner peripheral wall  202  into the central opening  21 , and is formed with four angularly spaced fastener holes  22 . An annular groove  24  is formed in the top side  200  between the inner and outer peripheral walls  202 ,  203 . The groove  24  has a groove bottom with an annular inner bottom section  240  disposed around the inner peripheral wall  202 , an annular intermediate recessed section disposed around the inner bottom section  240  and formed with an annular ball receiving recess  241  therealong, and an annular outer bottom section  244  disposed around the intermediate recessed section. The outer bottom section  244  extends radially and outwardly, and inclines upwardly with respect to an axis of the central opening  21 . In this embodiment, the inner bottom section  240  also extends radially and outwardly, and inclines upwardly with respect to the axis of the central opening  21 , thereby forming a pointed corner or apex  243  at a junction of the inner bottom section  240  and the intermediate recessed section. The ball receiving recess  241  has a plurality of metal balls  242 , which serve as a movable weight, disposed therein. 
     The ball restraining ring  30  is formed from a plurality of radial ring plate segments  31  that are disposed side-by-side in the groove  24  above the groove bottom. Each of the ring plate segments  31  has a plurality of angularly spaced barriers  311  that depend downwardly therefrom. Each of the barriers  311  is formed as an upright plate disposed in a radial direction with respect to the axis of the central opening  21 , and has a bottom side with an outer portion, an inner portion and an intermediate portion between the outer and inner portions. The outer portion has an inclined surface  33  that is seated slidably on the outer bottom section  244  to permit upward and downward sliding movement of the ring plate segments  31  along the outer bottom section  244 . The intermediate portion cis formed with a gate projection  35  that extends into the ball receiving recess  241  when the ring plate segments  31  slide downwardly along the outer bottom section  244  to locate the ball restraining ring  30  in a restricting position, where each of the metal balls  242  is restricted from moving freely by an adjacent pair of the barriers  311 , and that ceases to extend into the ball receiving recess  241  when the ring plate segments  31  slide upwardly along the outer bottom section  244  to locate the ball restraining ring  30  in a releasing position, where the barriers  311  cease to restrict and permit free movement of the metal balls  242  in the ball receiving recess  241 . The inner portion of the bottom side of each of the barriers  311  is seated on the inner bottom section  240  of the groove bottom when the ball restraining ring  30  is in the restricting position. Preferably, the inner portion is formed with a notch  32  for seating the same removably on the inner bottom section  240  at the apex  243  when the ball restraining ring  30  is in the restricting position. In this embodiment, each of the ring plate segments  31  has a width in a radial direction with respect to the axis of the central opening  21 , that is shorter than a width of the groove  24  measured in the radial direction. Each of the ring plate segments  31  further has a height in an axial direction of the central opening  21 , that is shorter than a depth of the groove  24  measured in the axial direction. The ring plate segments  31  are thus movable inside the groove  24  in both the radial and axial directions with respect to the axis of the central opening  21 . 
     The cover member  40  is used to cover the top side  200  of the ring member  20 . The cover member  40  is annular in shape to complement the ring member  20 , and has a central opening  41  aligned with the opening  21 . The bottom side of the cover member  40  is mounted securely on the top side  200  of the ring member  20  with the use of known high frequency welding techniques. 
     In use, the balancing ring is mounted securely on the bottom side or the top side of the rotor of the ceiling fan  10  via screw fasteners that extend through the fastener holes  22 . Referring to FIGS. 4 and 5, when the motor (not shown) of the fan  10  begins to operate, the balancing ring rotates. Upon rotation of the balancing ring above a certain speed, inertial forces acting on the ring plate segments  31  cause the inclined surfaces  33  of the barriers  311  to move upwardly along the outer bottom section  244 , thereby moving the ring plate segments  31  in both the radial and axial directions inside the groove  24 . Eventually, the gate projections  35  of the barriers  311  will cease to extend into the ball receiving recess  241 , thereby enabling the metal balls  242  to move freely in the ball receiving recess  241  to counteract any imbalance during rotation of the blades  11  of the fan  10 . However, in order for the metal balls  242  to effectively balance the fan, the balancing ring must be rotating at a sufficiently high speed to allow the metal balls  242  to counteract the imbalance. When the fan operates on low speed, there is not enough movement to allow the metal balls  242  to move freely and balance the fan. In fact, the random movement of the metal balls  242  at low fan speeds can actually cause an imbalance. Thus, it is important for the metal balls  242  to be held in the stable position when the fan slows down and runs on low speed. When the rotating speed of the balancing ring slows down, the inclined surfaces  33  of the barriers  311  will move downwardly along the outer bottom section  244 , thereby moving the ring plate segments  31  in both the radial and axial directions inside the groove  24  such that the gate projections  35  of the barriers  311  will once again extend into the ball receiving recess  241  so as to restrict movement of the metal balls  242  in the ball receiving recess  241 . Thus, the outer bottom section  244  and the outer portion of the bottom side of each of the barriers  311  cooperate to form lifting means, inside the groove  24 , for permitting movement of the ball restraining ring  30  in the groove  24  in response to rotating speed of the balancing ring. In order to balance the fan, the fan should run on high speed until the metal balls  242  achieve a balanced state. When the fan is turned off or switched to low speed, the metal balls  242  will be held in the balanced configuration. 
     Preferably, the number of metal balls  242  is fewer than the number of barriers  311 , e.g. 1:3, for best results. 
     Since the balancing ring is mounted securely on the rotor, and not on each of the fan blades  11 , the risk of untimely removal associated with the use of weights as taught in the prior art has been minimized, and the installation of the balancing ring of this invention can be conducted without the need for the assistance of a skilled technician. 
     Referring to FIGS. 6 and 7, the second preferred embodiment of a balancing ring according to the present invention is shown to also include a ring member  50 , a ball restraining ring  60  and a cover member  70 . 
     The ring member  50  has a top side  500 , a bottom side  501 , an inner peripheral wall  502  that confines a central opening  51 , and an outer peripheral wall  503 . Like the previous embodiment, an annular flange  510  projects radially from the inner peripheral wall  502  into the central opening  51 , and is formed with angularly spaced fastener holes  52 . An annular groove  54  is formed in the top side  500  between the inner and outer peripheral walls  502 ,  503 . The groove  54  has a groove bottom with an annular outer recessed section surrounded by the outer peripheral wall  503  and formed with an annular ball receiving recess  56 , and an annular inner section disposed between the outer recessed section and the inner peripheral wall  502 . The ball receiving recess  56  has a plurality of metal balls  561 , which serve as a movable weight, disposed therein. The annular inner section is formed with a plurality of angularly spaced ditches  55  that extend radially with respect to an axis of the central opening  51 . Each of a plurality of control balls  552 , which are larger than the metal balls  561  in diameter, is received in a respective one of the ditches  55 . Each of the ditches  55  is defined by a planar base wall  550  and an upwardly inclining wall  551  that extends from one end of the base wall  550  toward the outer recessed section. Preferably, each of the metal balls  561  and the control balls  552  has an upper portion that protrudes upwardly relative to the annular inner section of the groove bottom. 
     The ball restraining ring  60  includes a ring plate  61  that is disposed in the groove  54  above the groove bottom. The ring plate  61  has a bottom side that contacts the upper portions of the control balls  552 , and that is formed with a plurality of angularly spaced barriers  62  depending downwardly therefrom. The ball restraining ring  60  is movable inside the groove  54  between a restricting position, where each of the metal balls  561  is restricted from moving freely by an adjacent pair of the barriers  62 , and a releasing position, where the barriers  62  cease to restrict and permit free movement of the metal balls  561  in the ball receiving recess  56 . Preferably, each of the barriers  62  has a bottom end that is supported on the inner section of the groove bottom when the ball restraining ring  60  is in the restricting position. In this embodiment, the ball restraining ring  60  has a height in an axial direction of the central opening  51 , that is shorter than a depth of the groove  54  measured in the axial direction, thereby permitting movement of the ball restraining ring  60  inside the groove  54  in the axial direction with respect to the axis of the central opening  51 . 
     The cover member  70  is used to cover the top side  500  of the ring member  50 . The cover member  70  is annular in shape to complement the ring member  50 , and has a central opening  71  aligned with the opening  51 . The bottom side of the cover member  70  is mounted securely on the top side  500  of the ring member  50  with the use of known high frequency welding techniques. 
     In use, the balancing ring is mounted securely on the bottom side or the top side of the rotor of the ceiling fan (not shown) via screw fasteners that extend through the fastener holes  52 . Referring to FIGS. 7 and 8, when the motor (not shown) of the fan begins to operate, the balancing ring rotates. Upon rotation of the balancing ring above a certain speed, inertial forces acting on the control balls  552  cause the latter to move upwardly along the upwardly inclining wall  551  of the respective one of the ditches  55 , thereby urging the ring plate  61  upwardly for moving the ball restraining ring  60  in the axial direction inside the groove  54 . Eventually, the barriers  62  will cease to restrict the metal balls  561 , thereby enabling the latter to move freely in the ball receiving recess  56  to counteract any imbalance during rotation of the blades of the fan. However, in order for the metal balls  561  to effectively balance the fan, the balancing ring must be rotating at a sufficiently high speed to allow the metal balls  561  to counteract the imbalance. When the fan operates on low speed, there is not enough movement to allow the metal balls  561  to move freely and balance the fan. In fact, the random movement of the metal balls  561  at low fan speeds can actually cause an imbalance. Thus, it is important for the metal balls  561  to be held in the stable position when the fan slows down and runs on low speed. When the rotating speed of the balancing ring slows down, the control balls  552  will move downwardly along the upwardly inclining wall  551  of the respective one of the ditches  55 , thereby moving the ball restraining ring  60  in the axial direction inside the groove  54  such that the barriers  62  will once again restrict movement of the metal balls  561  in the ball receiving recess  56 . Thus, the upwardly inclining wall  551  of each of the ditches  55  and the control balls  552  cooperate to form lifting means, inside the groove  54 , for permitting movement of the ball restraining ring  60  in the groove  54  in response to rotating speed of the balancing ring. In order to balance the fan, the fan should run on high speed until the metal balls  561  achieve a balanced state. When the fan is turned off or switched to low speed, the metal balls  561  will be held in the balanced configuration. 
     Like the previous embodiment, the number of metal balls  561  is fewer than the number of barriers  62 , e.g. 1:3, for best results. 
     While the present invention has been described in connection with what is considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.