Abstract:
Disclosed herein is a container for holding a burnable coil bearing an active ingredient, such as an insecticide, insect repellant, deodorizer, or fragrance. The container includes a base having a raised coil support for mounting the coil and a spiral recess or spirally arrayed support peaks which permit air circulation beneath the coil and inhibit premature snuffing. The coil is enclosed by a cover having a downwardly depending hold-down aligned with the coil support to prevent the coil from moving in the container. The cover also has openings allowing air to pass into the container and vapors to be released. The cover is rotatably mounted to the base so that the cover openings can be selectively opened and closed to allow controlled venting and snuffing of the coil.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH/DEVELOPMENT 
     Not applicable 
     BACKGROUND OF THE INVENTION 
     The present invention relates to containers for burnable coils, and in particular, to containers that provide adjustable burn rates and controlled snuffing. 
     Burnable coils, such as mosquito coils and incense coils, are designed to provide sustained vapor release. As they burn slowly they are susceptible to being inadvertently extinguished, thereby rendering the coil ineffective. Inadvertent extinguishing can occur when the coil does not receive enough air for burning, or when too much heat is drawn from the coil by conduction to a contacting surface. 
     Ordinarily, burnable coils are impaled on a spaded end of a post suitably mounted into the ground or a mounting surface. The coils are held off the ground/mounting surface and open to the air, thereby reducing the chance of inadvertent extinguishing. However, this leaves the burning end free to be touched. Moreover, the burn rate is largely affected by the rate of air flow past the coil. As such, a burning coil can be burned too quickly or extinguished by a strong wind. 
     Burnable coil holders have been developed in which the coils are enclosed inside a vented container. These containers shield the coil from excessive wind, are aesthetically pleasing and prevent accidental contact with the burning end of the coil. For example, U.S. Pat. No. 6,061,950 discloses a covered burnable coil holder in which the coil is mounted on a spade projecting from a base enclosed by a cover. The base has a number of small non-metallic pointed elements projecting upward to support the coil off the surface of the base (if it were to sag downwardly from the spade). The disclosure of this patent and of all other publications referred to herein are incorporated by reference as if fully set forth herein. 
     While a significant improvement, to extinguish a burning coil the cover had to be removed and the coil snuffed out directly. Further, if the holder was bumped accidentally, the coil might be jarred off the spade and snuffed. 
     Accordingly, a need still exists for an improved burnable coil holder. 
     BRIEF SUMMARY OF THE INVENTION 
     In one aspect the invention provides a container for a burnable coil having a base with a coil support for mounting the coil adjacent the coil&#39;s inward end. There is also a cover positioned on the base and having a downwardly depending hold-down alignable with the coil support. The cover also has openings for permitting the passage of air into the container. The term “cover opening” is defined to include both upwardly and sidewardly presented openings, as well as arrangements wherein space is purposefully left at the cover&#39;s margin, where the cover meets the base. The floor of the base and the hold-down sandwich the coil to prevent its movement during the burning process. 
     In preferred forms the coil support includes an upwardly extending projection, and the cover includes a downwardly extending leg having at least one foot. The base has at least one arc-shaped slot with an enlarged area through which the foot can readily pass and a narrow area through which the foot cannot readily pass. The arc-shaped slot is positioned to allow the cover to be rotated so that, as the leg is moved toward a first end of the slot, the openings are increasingly closed and, as the leg is moved toward the opposite end of the slot, the opening is increasingly opened. Preferably, when the leg is adjacent a first end of the slot the openings are essentially completely closed and when the leg is adjacent an opposite end of the slot the opening is essentially fully opened. 
     The base includes a ring of upstanding tabs spaced apart by gaps, the tabs and a floor of the base defining a cavity for receiving the coil. The cover has a top surface with walls depending downwardly therefrom that are sized to fit around the ring of tabs and enclose the cavity. When the cover is fixed to the base it can rotate between a closed position in which the wall openings align with the tabs and an open position in which the wall openings at least partially align with the gaps between the tabs. This provides venting control for the container. 
     In another aspect a comfort contact area can be provided on the cover by outwardly bulging grip areas formed at junctions between the cover walls. 
     To minimize the likelihood of undesired snuffing the base can either have a spiral depression in an upper surface of a floor of the base (so that only extreme sag will lead to a contact of an outer portion of the coil with the floor) or an array of spirally disposed pointed peaks extending up from the floor of the base (to inhibit sagging without significant contact with the outer portion of the coil). 
     It is preferred that the cover is made of a thermoset plastic and the base is made of a thermoset plastic or a sand-filled resin. Further, it is preferred that the base has a concave bottom surface and the cover has a convex top surface. This permits the containers to be nested for compact storage and shipment. 
     In another aspect the invention provides a container for controlling burn rates of a burnable coil. There is a base having a coil support for mounting the coil on the base, and a cover having openings for permitting the passage of air into the container. The cover is rotatably mounted on the base so that the cover openings can be selectively opened and essentially closed by relative rotation of the cover relative to the base. 
     In still other forms, the invention provides a mosquito coil having an upper and a lower surface, and an opening extending between the surfaces adjacent its inward end. The opening has a Saturn-shaped cross section. “Saturn-shaped” is defined as describing a circle with a line extending from side to side, through its center, somewhat resembling the planet Saturn and its rings, with the rings viewed edge-on. Alternatively, there may be two openings extending between the surfaces adjacent the coil&#39;s inward end, each opening having a different cross sectional shape (e.g. circular and elongated or square). 
     Thus, the present invention provides a container for a burnable coil allowing the burn rate, and thereby vapor release rate, to be easily controlled without contacting the coil. This is accomplished by rotating the cover in either direction to cause the openings to be more or less obstructed by the base. 
     Grip areas on the cover allow for easy manipulation of the cover as well as insulate one&#39;s hands from the heat of the coil. Inadvertent snuffing is avoided by the raised coil support, as well as the raised peaks or depressed recesses. 
     The coil is firmly pinned in place against movement within the container, being held between the coil support and the downwardly depending hold-down, and the coil support also contains a portion that will insure snuffing of the coil before the hold-down feature is contacted by the burning coil, thus allowing the hold-down and the cover to be made of materials that cannot withstand the intimately applied heat of the burning zone of a burning coil. 
     Alternatively described, the container of the invention for a burnable coil includes a base having a coil support for mounting the coil. The container also has a cover rotatably positionable on the base, the cover having at least one cover opening for permitting the passage of air into the container, the cover and base being so constructed that a user can rotate the cover on the base to increasingly close and open the cover opening. 
     Alternatively, the invention may be described as a container for a burnable coil having a base and a cover positionable on the base to enclose the coil as it burns. The base has a coil support for mounting the coil adjacent an end of the coil. The coil support has an upper surface to receive a portion of the coil in directly contacting relation, the upper surface being sufficiently heat absorbing as to cause a burning coil contacting the upper surface to extinguish when the fire reaches the margin of the flat upper surface. It is not required that the upper surface be flat, although that is preferred so as to provide better thermal drain from the coil to encourage prompt extinguishment of the coil. 
     The foregoing and other advantages of the invention will appear from the following description. In that description reference is made to the accompanying drawings which form a part hereof and in which there is shown by way of illustration preferred embodiments of the invention. These embodiments do not represent the full scope of the invention. Thus, the claims should be looked to in order to judge the full scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of an adjustable container of the present invention with an insect coil disposed therein; 
     FIG. 2 is an exploded view of the container and insect coil of FIG. 1; 
     FIG. 3 is a top view of a base of the container of FIG. 1; 
     FIG. 4 is a cross-sectional view taken along line  4 — 4  of FIG. 3; 
     FIGS. 5A-5C are fragmentary views showing a cover of the container of FIG. 1 in various positions, FIG. 5A showing the cover positioned so that the vents are partially open, FIG. 5B showing the cover positioned so the vents are closed and FIG. 5C showing the cover positioned so the vents are fully open; 
     FIG. 6 is a vertical cross-sectional view taken along line  6 — 6  of FIG. 1; 
     FIG. 7 is a partial sectional, partial side elevational view, showing that the cover and base are nestable; 
     FIG. 8 is a top view of the cover; 
     FIG. 9 is a perspective view of an alternate embodiment of the base in which the floor of the base has an array of raised spikes; 
     FIG. 10 is a view similar to FIG. 6, albeit with the base of FIG. 9; and 
     FIGS. 11A-11C show inner ends of insect coils with various through openings. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An adjustable insect coil container generally  10  includes a base  12  and a cover generally  14  that mate to enclose a burnable coil  16 . The cover  14  has a generally hexagonal top surface  18  from which six side walls  20  depend downwardly. Each side wall  20  includes a pair of longitudinal vents  22 , and the intersections of the side walls  20  present outwardly bulging six grip areas  24 . 
     Depending downwardly from the two opposite side walls are a pair of legs  26  having radially outwardly directed feet  28  at their bottom end. The legs  26  are designed to engage the base  12 , as described in detail below. As shown in FIG. 6, the cover  14  also includes a downwardly depending coil hold-down  27 , preferably tubular and located off-center of the cover  14 . The hold-down may alternatively be a slab or other structure. The cover  14  is preferably made of a thermoset plastic having a sufficiently high melting point to sustain the heat of a burning coil without being damaged. 
     Preferably, the coil  16  has a mounting end  30  and an opposite burning end  32 . 
     Referring to FIG. 11B, a Saturn-shaped opening  34  is formed in or through the mounting end  30  of the coil  16 . This unique opening allows the coil  16  to be used with the container  10  of the present invention as well as with conventional spade-type holders and containers, such as that disclosed in U.S. Pat. No. 6,061,950. The coil  16  is otherwise of the type disclosed in U.S. Pat. No. 5,657,574. 
     A variety of other spiral burnable coils could also be used that incorporate the desired materials to be dispersed (e.g. insecticides, insect repellants, deodorizers, fragrances and the like). Moreover, the mounting end  30  could have other mounting openings, such as a cylindrical through hole  35  as shown in FIG. 11A alone, or separate rectangular and circular openings  35  and  37  as shown in FIG.  11 C. 
     The base  12  is preferably a sand-filled polymer resin or a suitable thermoset plastic formed to include six, equally-sized upstanding tabs  36  spaced apart from each other and arranged in a circle. The tabs  36 , in conjunction with a bottom floor  38 , define a cavity  40  in which the coil  16  can be disposed. The cavity  40  also acts to contain residual ash left over from a burnt coil  16 . 
     Eccentrically located (to be in vertical alignment with the hold-down  27  of the cover  14 ) is a coil support  42  projecting upward from the floor  38 . The coil support  42  has a horseshoe-shaped ridge  44 , the inner diameter of which is designed to envelope the curved outer surface of the mounting end  30  of the coil  16 . The coil support  42  also includes an upwardly projecting peg  46  which engages with the opening  34  in the mounting end  30  of the coil  16 . The coil support  42  has a flat surface that can draw sufficient heat away from the contacting mounting end  30  of the coil  16  to snuff out a burning coil before reaching the ridge  44 . Extinguishing the coil  16  before the mounting end  30  is burnt prevents the hold-down  27  of the cover  14  from coming in contact with a burning coil, which reduces the possibility of the cover being deformed. 
     The ridge  44  and peg  46  work to keep the mounting end  30  of the coil  16  on the coil support  42  elevated off of the floor  38 . The floor  38  of the base  12  also has a spiral-shaped depression  48  designed to follow the spiral path of the coil  16 . The recess  48  is slightly wider than the width of the coil  16 . As such, a sagging coil will first fall into the recess in a manner that it is still above the floor. This makes heat loss to the base less likely. The spiral-shaped depression  48  also provides a vision reference for properly orienting and mounting the coil  16  within the base  12 . By aligning the coil  16  with the depression  48  the user will be sure to mount the mounting end  30  of the coil  16  to the coil support  42 . 
     Referring now to FIGS. 2 and 3, the base  12  has a pair of arc-shaped slots  50  located opposite from each other in a circumferential flange  52  extending around the tabs  36 . The slots  50  receive the legs  26  of the cover  14 . The slots  50  have an enlarged opening area  54  through which the feet  28  initially can fit when attaching or removing the cover  14 , as shown in FIG.  5 A. When inserted into the slots  50 , the legs  26  extend down far enough so that the feet  28  rest beneath a lip surface  56  of the base  12 , as shown in FIG.  6 . Thus, when the cover  14  is rotated, as in the positions shown in FIGS. 5B and 5C, the lip  56  prevents the cover  14  from being pulled away from the base  12 . 
     As shown in FIG. 1, the base  12  and the cover  14  cooperate to form side air passages  60  allowing air to enter the container  10  and burnt vapors to exit during burning of the coil  16 . The cover  14  can be rotated as desired to vary the degree that the vents  22  are obstructed. The base slots  50  are sized so as to positively stop the cover  14  in fully open and fully closed positions by contact with the legs  28  of the cover  14 . 
     Thus, as shown in FIG. 5B, when the cover  14  is fully rotated counter-clockwise, the tabs  36  of the base essentially completely obstruct the vents  22  in the cover  14 . In this way a burning coil can be snuffed without touching the coil by hand. Conversely, when the cover is fully rotated clockwise, the vents  22  align with air gaps between the tabs  36  and allow maximum air and vapor passage therethrough. Intermediate positions provide for intermediate bum rates. 
     As shown in FIG. 4, the base  12  has a concave underside  70  that is shaped to mate with the convex top surface  18  of the cover  14 . Multiple containers  10  can be compactly nested or stacked securely one upon another for storage or shipping. 
     The container  10  can be used, for example, to hold an insect coil containing a suitable insecticide active ingredient. As mentioned, however, the container  10  may also be used with other burnable coils having other types of active ingredients. In any event, the container  10  is preferably used by setting the base on a flat surface in an room or outdoor space. The coil  16  is then inserted into the base  12  so that the mounting end  30  of the coil is fit onto the coil support  42 , with the peg  46  in the opening  34 . Either before or after the coil  16  is placed in the base  12  the burning end  32  is lit with a match or lighter until the coil  16  begins burning. The cover  14  is then fit over the base  12  so that the legs  26  align with the slots  50  such that the feet  28  fit through the enlarged opening  54 . The cover  14  can then be adjusted by grasping the grip areas  24  and rotating the cover  14  as needed to open the vents  22  so as to achieve a desired vapor release rate. 
     The cover  14  is preferably adjusted using the grip areas  24 . This is because after prolonged burning portions of the cover  14  can become warm. The grip areas  24  lie farther outside the circumference of the tabs  36  than the vented area. As such, the grip areas  24  are cooler than other parts of the cover  14 . The grip areas  24  are located at the corners of the side walls  20 , which are natural grip points. 
     When the cover  14  is attached to the base  12  the coil is held against the coil support  42  by the hold-down  27 , as shown in FIG.  6 . If the container is accidentally tipped over, the coil  16  will remain burning without being extinguished. 
     Another embodiment of the container is shown in FIGS. 9 and 10 as reference numeral  10 A. Similar components are shown with similar numbers, albeit with the suffix “A”. As in the first embodiment, the container  10 A includes a base  12 A and a cover  14 A for enclosing a coil  16 A. The coil  16 A is again supported above the floor  38 A by a raised coil support  42 A. However, here rather than a recess, the base  12 A has a plurality of support peaks  100  around the coil support  42 A for supporting the coil  16 A in the event it sags downwardly. As with the recess in the first embodiment, the support peaks  100  allow air to pass beneath the coil  16 A. Preferably, the support peaks  100  have a conical or pyramidal shape, terminating upwardly to a point so that they make as little point contact with the coil  16 A as possible. The coil support  42 A extends higher than the support peaks  100 . 
     While specific embodiments have been shown, various modifications falling within the breadth and scope of the invention will be apparent to one skilled in the art. For example, the container of the first embodiment could include both a recess as well as the support peaks of the second embodiments. Also, while the container has been described with two identical cover legs and corresponding base slots, these features could be of different size or shape so that the cover can be fit on the base in only one orientation. Also, the cover could include any number of legs and be made to rotate in any direction to open and close the vents. Moreover, the configuration the cover, coil support ridge and the upstanding tabs of the base could be any suitable shape. Thus, the following claims should be looked to in order to understand the full scope of the invention. 
     Industrial Applicability 
     The above disclosed invention provides a container and snuffer for a burnable coil.