Abstract:
A chimney damper for round flues that includes a rigid peripheral frame surrounding an open window area, a cap moveable toward and away from the open window to selectively close and open the same and springs interconnecting the cap and frame resiliently urging the cap to an open position. The square, rectangular, or round frame includes a shirt adapted to form or connect to a cylindrical base which comprises a round open window and thus can be configured for use on a round flue. The springs are preferably torsion springs and are located within the cap assembly and the open window area defined by the peripheral frame. The cap is guided during its movement toward and away from the frame by the springs and during such movement the cap rotates a partial turn relative to the frame to which it is connected by the springs.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority from U.S. Provisional Application Ser. No. 61/395,254 filed on May 12, 2010 is incorporated by reference herein in its entirety. Reference to documents made in the specification is intended to result in such patents or literature cited are expressly incorporated herein by reference, including any patents or other literature references cited within such documents as if fully set forth in this specification. 
     
    
     TECHNICAL FIELD OF INVENTION 
       [0002]    This invention relates generally to a spring biased chimney damper including locking mechanism and more particularly to improvements thereto. 
       BACKGROUND OF INVENTION 
       [0003]    The application incorporates by reference Applicant&#39;s U.S. Pat. No. 7,422,519 which issued on September 2008 and published as publication US 2005/0250433 on Nov. 10, 2005 from application Ser. No. 11/080/355 filed on Feb. 17, 2005 and claims priority from U.S. application Ser. No. 10/927,783 filed on Aug. 27, 2004, now abandoned. 
         [0004]    The prior art shows various type of dampers without and without spring means to hold the cap away from the frame in or on the chimney flue when not in use. For instance, U.S. Pat. No. 5,125,869 granted on Jun. 30, 1992, and U.S. Pat. No. 5,556,329 granted on Sep. 17, 1996 disclose a conventional spring biased chimney damper. 
         [0005]    Typically, these prior art devices include a frame defining an open window area, a cap for selectively covering and uncovering the open window area, and spring means inter connecting the cap and frame and biasing the cap to it&#39;s open position. The springs are multi-component and connected to the frame outside of the window area. There may be a poorly designed alignment means to align the cap over the window opening as it is operative only the final phase of it&#39;s movement to the closed position. No means is provided for selectively adjusting the spacing between the cap and the frame in the cap open position. 
         [0006]    Some chimney dampers include a lock mechanism to keep the damper in an open position in case of a chimney fire comprising a fusible link connected to spring means and in case of over heating, due to for example a chimney fire, the link melts causing the spring to move into a position in which it locks the cap in an open position. This fusible link must be replaced after each occurrence of overheating and because of the in use position of the damper on top of the chimney it is difficult to replace. 
         [0007]    Moreover, some chimney damper embodiments require that the cap turn a quarter turn during each of the closing and opening movements. In another embodiment, the cap does not rotate and is captive in an outer skeleton frame limiting movement of the cap to reciprocal movement only wherein the spring system is connected to a plate that can move reciprocally on a shaft as well as rotate on that shaft. 
       SUMMARY OF THE INVENTION 
       [0008]    The chimney damper disclosed in the present invention includes a rigid peripheral frame surrounding an open window area corresponding generally to that of an end of the flue having a square, rectangular, or round shape. The frame includes a shirt extending inwardly therefrom adapted to form or connect to a cylindrical base which comprises a round open window and thus can be configured for use on a round flue. A cap is included for covering the open window area. A round plate connecting to the bottom of the cap is interposed between the cap and the frame base. Spring means interconnecting the frame base and plate causes the plate to rotate relative to the frame base during opening and closing of the damper. The spring means biases the plate and cap connected thereto in a direction away from the frame base to a window open position. The cap is movable toward the frame against a spring bias to overlie and thereby close the open window area. Means pivotally interconnecting the cap and the plate are included together with means preventing rotation of the cap relative to the frame base when the cap is moved toward and away from the frame base during respectively closing and opening of the damper. 
         [0009]    An object of the present invention is to provide an improved means that prevents rotation of the cap while the cap is being moved from one to the other of an open and closed position. 
         [0010]    A further object of the present invention is to provide a means as described above while at the same time avoiding the use of an external frame for guiding the cap during it&#39;s movement toward an open and closed position. 
         [0011]    Another object of the present invention is to provide an improved means for maintaining alignment of the cap outer downwardly directed peripheral flange with the upwardly directed outer peripheral flange on the chimney flue mounting flange. 
         [0012]    An object of the present invention is to provide an improved spring arrangement biasing the cap to an open position. 
         [0013]    A further object is to provide a spring arrangement which is self guiding and requires no additional guide means for aligning the cap over the open window area of the frame. 
         [0014]    Another object of the present invention is to provide a chimney damper for use on round flues. 
         [0015]    Another object of the present invention is to provide a chimney damper which is inexpensive and easy to manufacture with relatively few moving parts. 
         [0016]    In keeping with the forgoing there is provided a flue damper comprising: a rigid peripheral frame surrounding an open window area, said open window area being round, a round cap for covering said open window area, said cap being large enough to receive the round portion of said rigid peripheral frame, and spring means connecting said cap assembly to said frame, said spring means being located within said open window area and biasing said cap assembly in a direction away from said frame to a window open position, said cap assembly being forceably movable against said resilient bias toward said frame to overlie and thereby close said open window, and wherein said spring means includes at least three torsion spring members biasing said cap assembly from said window frame and capable of guiding said cap assembly to close said window without further guide means. 
         [0017]    More particularly, the chimney damper of the present invention includes a rigid first peripheral frame surrounding an open window area, a cap including a plate of slightly smaller diameter nested or affixed to the underside of the cap, wherein moveable of the plate and cap toward and away from the open window to selectively close and open the same is accomplished by a plurality of springs interconnecting the plate with a base of the frame resiliently urging the cap to an open position. One end of the springs are connected to the bottom or sides of the plate and the other ends of the springs are attached to the base of the frame. The cap is mounted on the plate and allowed to pivot relative to the cap. The springs and the arrangement thereof are such as to cause the plate to rotate relative to the frame base during opening and closing of the damper with the rotation being about one quarter turn. An articulated link interconnects the frame base and coupling between the plate and the cap so as to prevent pivoting of the cap when moving the cap from one to the other of an open and a closed position. 
         [0018]    Other objects, features, and advantages of the invention will be apparent with the following detailed description taken in conjunction with the accompanying drawings showing a preferred embodiment of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    A better understanding of the present invention will be had upon reference to the following description in conjunction with the accompanying drawings in which like numerals refer to like parts throughout the several views and wherein: 
           [0020]      FIG. 1  is a perspective front view of a chimney damper showing the cap connecting to the base and peripheral frame; 
           [0021]      FIG. 2  is a perspective front view of the chimney damper of  FIG. 1  showing a plate affixed to the underside of the cap and the ends of the springs extending from the frame base and extending to the plate; 
           [0022]      FIG. 3  is a perspective upper view showing a top of the plate with the cap removed and exposing the hidden torsion spring portions; 
           [0023]      FIG. 4  is a perspective view without the cap and showing the damper in a partially closed condition whereby the plate is rotated with respect to the frame base and compressed thereby; 
           [0024]      FIG. 5  is a side view of the spring attachment and stop lug; 
           [0025]      FIG. 6  is an oblique view of a torsion spring; and 
           [0026]      FIG. 7  is a perspective view of a torsion spring of a chimney damper configured to fit a round flue. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0027]    As best illustrated in  FIGS. 1 and 2  a preferred embodiment of the chimney damper  10  comprises a frame  20  having a peripheral lip extending along a edge thereof for mounting to a brick or concrete or metal flue pipe or chimney. A flange of skirt  25  extends from the peripheral edge of the frame  20  connecting to a short cylindrical base  23  extending upward therefrom sized in accordance with the flue pipe. The damper frame  20  includes an open window area  21  that is selectively opened and closed by moving a cap  30  upward or downward respectively away from and toward the frame  20 . As shown, frame  20  has a peripheral flange  24  configured to fit onto a square flue. The cap  30  is connected to a disk or plate  46  by a screw  34  extending from the bottom surface of the cap  30  which is inserted through a center hole of the plate and secured there through by a nut  32 . The plate or disk  46  is connected to frame  20  by a plurality of spring means  40  which are attached to the sides or bottom of the plate  46  and to the short cylindrical base  23  extending upward from a flange or skirt  25  adapted for connecting the peripheral frame  24  to the base  46  in order to biase the cap to it&#39;s open position. The cylindrical base  23 , shirt  25  and peripheral frame  24  can be formed as individual members affixed together by welding, rivets, screws, or a friction fit; however, the unit can easily be formed as an integral one piece design from a pressed or molded part. 
         [0028]    As shown in  FIGS. 3 and 5 , cap  30  has been removed from disk  46 . Spring means comprises a plurality of torsion springs  40 . As shown in the preferred embodiment four wire torsion springs  40  are employed, each one consisting of three arm portions  41 ,  42 ,  43  and a coiled portion  44  at one end. The arm portion  43  of the spring  40  is pivotally anchored to frame base  23  by a coiled portion  44 . The coiled portion  44  is held by a pin  22  secured to frame base  23  and projects into an open window area  21 . The coiled portion  44  of the spring  40  is held between two washers  60 . Bracket  56  is fastened to frame  20  by pins  22  and  62 . Lug  58  on bracket  56  acts as a stop for arm  43  preventing it from rotating up to a perpendicular attitude when damper  10  is open. Therefore, lug  58  keeps arm portion  43  biased toward a closing attitude so that when the plate  46  and cap  30  is first urged toward frame  20 , it starts smoothly rotating in a controlled manner in a clockwise direction as viewed from above. 
         [0029]    The spring means  40  comprises four equal spaced wire springs  41  each having one of the opposite ends thereof fitting into an elongate sleeve secured to an inside corner of the frame base  23  and a stub leg at the other end that projects into and passes though a hole and is pivotally connected to a plate  46 . Means for holding such as a ‘C’-clip (or pressed on tight fit washer or the like) on the outer end of the leg such as is illustrated in  FIG. 4 , keeps the leg and coupling inter-connected. An enlargement at the end such as a cap nut or the like retains the post on the cap member and a loose connection allows the post to oscillate during opening and closing of the damper. The other end of the post has the previously described through hole transverse to the axis of the post or alternatively a slot into which the end of the spring can project and loop around a pin. 
         [0030]    The wire springs bend and lie between the cap  30  and frame base  23  when the damper is in it&#39;s closed state. To accomplish this it is necessary for the plate  46  to rotate a partial turn, (approximately one quarter turn), relative to the frame. The cap is mounted on the plate  46  by a coupling means and allowed to rotate with the plate  46 ; however, the cap  30  can be prevented from rotating with the plate  46  by use of a rotation preventing link connecting at one end thereof to the frame base  23  and at the other end to the coupling means. Use of a biasing mechanism to prevent rotation of the cap  30  with respect to the plate  46  of the chimney damper  10  provides an embodiment suitable for use with rectangular chimney openings. Moreover, the device can be modified for use with hexagonal, octagonal or other unusually shaped chimney openings. 
         [0031]    Opening and closing the damper is accomplished by rotation of the plate  46  and compression of the springs and lowering the cap toward the frame base  23 . The pin  64  is attached to the bottom surface of the plate  46 . The cable  68  is attached to the pin  64  at its upper free end and extends down through the flue and into the upper fireplace where a handle  66  is connected at its lower free end. Thus, a user can pull handle  66  to close or reduce the volume of the damper  10 . In its open position, when damper  10  is closed by pulling handle  66 , the arms  43  will be urged in a downward direction from a near vertical position toward a horizontal position which causes the plate  46  to rotate in a clockwise position and cap descend toward the frame base  23 . 
         [0032]    The cap may optionally utilize a seal means for example maybe a “U”-shape rubber, or the like gasket member  27  that fits onto the upper edge of the flange at the top of the frame base  23 . It provides sealing contact with the under face of the cap when the latter is in it&#39;s closed position covering the open window of the frame. Obviously the gasket could be made of suitable material such as graphite, silicon, soft metal, or synthetic polymer materials to withstand heat that would be encountered even when a chimney fire occurs. 
         [0033]    It is contemplated that cable  68  could be replaced with a chain, rod or any other attachment means appropriate for pulling cap  30  toward frame  20 . 
         [0034]    As shown best in  FIG. 3 , the spring arm portion  43  forms an approximate right angle to the torsion arm portion  42 . It is not necessary that this be a right angle, but it must be an angle that allows rotating arm  43  to twist and therefore apply a torque to arm portion  42 . Likewise, torsion arm portion  42  forms an approximate right angle with stop arm portion  41 . And similarly, it is not necessary that this be a right angle, but it must be an angle that allows arm portion  41  to prevent torsion arm portion  42  from turning freely. 
         [0035]    Arm portions  42  and  43  of spring  40  are pivotally attached to the plate  46  by a block  53  disposed on the upper surface close to the outer edge along the periphery of the plate. Each one of the arm portions  42  and arm portions  41  are attached to a respective block  51  evenly spaced apart from one another along the periphery of the plate  46 . As the pin  64  is pulled toward frame  20 , arm  43  is rotated toward frame  20  because coil portion  44  rotates around pin  22 . This rotating motion causes torsion arm portion  42  to twist because arm portion  41  prevents arm  42  from rotating in blocks  51  and  53 . Therefore a torsion effect is realized within arm portion  42 , which acts as a torsion spring. 
         [0036]    It is contemplated that blocks  51 - 54  may be replace with U-brackets, eyelets screws or any other suitable means that can pivotally attach spring portions  41 - 43  to disk  46 . 
         [0037]    As shown in  FIG. 4 , all four springs  40  react in the same way and therefore guide disk  46  and cap  30  down to frame  20  in a rotating manner. 
         [0038]    Other embodiments could use three, five or more evenly spaced torsion springs to bias the cap assembly above the frame. Also, note that with the torsion springs evenly spaced and pivotally connected to the frame as shown, no other guiding means is necessary. The springs keep the damper cap in alignment as it is urged down onto the window frame. 
         [0039]    Frame  20  is shown in  FIGS. 1-4  in a configuration wherein a round window  21  has been configured within frame  20  which fits a square flue. Another embodiment contains a frame which is configured to fit a rectangular flue. The chimney cap maybe manufactured in rectangular or square configurations that fit conventional flues of the following nominal sizes: 8″×8″; 8″×17″; 9″×13″; 13″×13″; 13″×18″; 18″×18″ or any size circular flue as well. 
         [0040]    Still another embodiment, shown in  FIG. 7 , contains a frame with flange  26  which is configured to fit a round flue. 
         [0041]    The foregoing detailed description is given primarily for clearness of understanding and no unnecessary limitations are to be understood therefrom, for modification will become obvious to those skilled in the art upon reading this disclosure and may be made upon departing from the spirit of the invention and scope of the appended claims. Accordingly, this invention is not intended to be limited by the specific exemplification presented herein above. Rather, what is intended to be covered is within the spirit and scope of the appended claims.