Abstract:
A device for containing a camp fire reduces the amount of smoke produced by the fire. The device reduces the amount of smoke by supplying air to the top of the fire to increase the combustion and thus reduce the smoke produced. In one configuration of the device, the air supplied to the top of the tire is heated prior to being introduced to the top of the fire. The disclosure also provides a configuration wherein the preheating of the air simultaneously cools the outer surface of the device.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/976,639 filed Apr. 8, 2014; the disclosures of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field 
         [0003]    The invention generally relates to devices used to contain fires and, more particularly, to an outdoor fire containment device commonly known as a fire pit. Specifically, the invention relates to a fire pit configured to reduce the amount of smoke produced from the fire burning in the device. 
         [0004]    2. Background Information 
         [0005]    People enjoy burning small camp fires in their backyards. These fires are used for general enjoyment and for cooking. One drawback with a backyard campfire—especially one made from a soft wood or a wood containing water—is the smoke generated from the fire. The smoke can infiltrate the owner&#39;s house and neighbors&#39; houses. This problem has led some cities and communities to completely ban backyard campfires. Some people use fire pits to control and contain their camp fires. In some communities, the use of a fire ring or fire pit is mandatory. A problem with some fire pits is that parts of them become hot and are thus dangerous to those who unexpectedly contact the hot elements of the fire pit. 
       SUMMARY OF THE DISCLOSURE 
       [0006]    The disclosure provides a device for containing a camp fire that reduces the amount of smoke produced by the fire. The device reduces the amount of smoke by supplying air to the top of the fire to increase the combustion and thus reduce the smoke produced. In one configuration of the device, the air supplied to the top of the fire is heated prior to being introduced to the top of the fire. 
         [0007]    The disclosure also provides a configuration wherein the preheating of the air simultaneously cools the outer surface of the device. 
         [0008]    The disclosure provides the body of the device in the shape of right-cylinder with a generally closed-off bottom wall and an upper lip that overhangs the sidewall. The diameter of the device is about twice the height. Combustion air is provided to the fire under the overhanging lip. This configuration has been found to reduce the amount of smoke produced by a fire burning in the device. 
         [0009]    The disclosure provides one configuration having a double sidewall design such that the two concentric spaced sidewalls define the air flow passage for introducing the combustion air to the top of the fire. This air flow passage is disposed essentially continuously about the circumference of the device. Another configuration uses a plurality of individual passages to deliver the air. 
         [0010]    A grilling screen may be used directly on top of the device or held over the device by a stand. 
         [0011]    The body of the device is supported by a plurality of legs to allow air to be drawn into the device from the bottom wall of the device. Shields are used on the inside of the bottom wall of the bottom to prevent these holes from directly clogging and to prevent ashes to fall out of the device through the holes. 
         [0012]    The disclosure also provides a combustion chamber having a width designed relative to its height such that air supplied to the top of the fire is able to reach the center of the fire for good combustion. An overhanging lip is used to direct the air radially inwardly. 
         [0013]    The individual features may be combined in different combinations than specifically described below to form different configurations of the device of the disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a perspective view of an exemplary configuration of the smokeless outdoor fire pit. 
           [0015]      FIG. 2  is a section view taken along line  2 - 2  of  FIG. 1 . 
           [0016]      FIG. 3  is a section view taken along line  3 - 3  of  FIG. 1 . 
           [0017]      FIG. 4  is a section view taken along line  4 - 4  of  FIG. 1 . 
           [0018]      FIG. 5  is a front view of the fire pit of  FIG. 1 . 
           [0019]      FIG. 6  is a right side elevation view of  FIG. 5 . 
           [0020]      FIG. 7  is a left side elevation view of  FIG. 5 . 
           [0021]      FIG. 8  is a rear elevation view of  FIG. 5 . 
           [0022]      FIG. 9  is a top plan view of  FIG. 5 . 
           [0023]      FIG. 10  is a bottom plan view of  FIG. 5 . 
       
    
    
       [0024]    Similar numbers refer to similar parts throughout the specification. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    An exemplary configuration of fire pit device of the disclosure is indicated generally by the numeral  2  in the accompany drawings. Device  2  generally includes a main body  4  supported above the ground by a plurality of legs  6 . A rim  8  is disposed about the top of main body  4 . Rim  8  may be used to support cooking tools, grills, or as a protective bumper. Device  2  provides a safe and convenient place for one to burn a small fire that can be used for cooking or general enjoyment. The fire is burned in the cavity defined by main body  4 . Device  4  may be made from any of a variety of fire-resistance materials. Main body  4  may be fabricated from steel and protected with a heat-resistant paint. 
         [0026]    One feature of device  2  is that it is configured to reduce the amount of smoke produced by the fire burning in main body  4 . The reduction in smoke is achieved by supplying heated combustion air to the top of the fire. This air is supplied through a plurality of upper air supply openings  10  defined by main body  4  adjacent the upper end  12  of main body  4 . Openings  10  may extend about the entire circumference of body  4 . Openings  10  may be evenly spaced. Air is supplied to upper air supply openings  10  through an air supply duct  14  that extends from an inlet  16  disposed adjacent the lower end  18  of main body  4  to openings  10 . In one configuration of device  2 , air supply duct  14  is disposed about the entire circumference of main body  4  with only a plurality of supports  20  interrupting the air flow through duct  14 . Supports  20  are disposed closer to lower end  18  than upper end  12 . In another configuration, duct  14  may be divided into a plurality of adjacent or spaced ducts. Positioning air duct  14  along the sidewall of main body  4  allows the air flowing up through duct  14  to be heated before it exits duct  14  to aid the combustion. 
         [0027]    In the exemplary configuration, duct  14  is defined by inner  30  and outer  32  concentric sidewalls of body  4 . The lower ends of sidewalls  30  and  32  are spaced and not connected to define inlet  16 . The upper ends of sidewalls  30  and  32  are joined together by a cap  34  so that all openings  10  define the outlet of duct  14 . In another configuration, the lower ends of walls  30  and  2  are joined and a plurality of inlets  16  are defined. When a fire is burning in main body  4 , inner sidewall  30  is heated to draw air into inlet  16  where it is warmed. The warmed air rises within duct  14  and exits through openings  10  to the top of the fire. Cap  34  projects radially inwardly over the openings  10  to form a lip that helps to direct air from openings  10  toward the middle of the fire. The warmed air assists the combustion and thus reduces the amount of smoke produced by the fire. In situations where the fire is producing an undesirable amount of smoke, adding fuel to the fire is suggested in order to increase the amount of heat available to warm the air in duct  14 . The spaced sidewalls  30  and  32  and the process of drawing cool air between the walls where it is warmed reduces the temperature of outer sidewall  32 . In some situations, outer sidewall  32  may be touched by the hand without danger even while inner sidewall  30  is too hot to touch without pain. 
         [0028]    Main body  4  is provided in the form of a cylindrical cup with inner sidewall  30  forming a right angle with the bottom wall  40  of main body  4 . The height of main body  4  is about half of the diameter with the lip formed by cap  34  extending inwardly about a half inch to three inches. In one configuration, the height of main body  4  is one foot with the diameter being two feet. These dimensions have been found to provide desirable results with the air supplied through openings  10  being radially close enough to the center of the fire to reducing the amount of smoke produced by the fire. 
         [0029]    Air inlets  42  are defined by bottom wall  40 . Inlets  42  are capped with shields  44  that have open ends  46 . Shields  44  help to prevent inlets  42  from becoming clogging. Shields  44  also prevent ashes and fire fuel from falling directly out of main body  4 . Shields  44  also prevent the cool air from under main body  4  from being pulled directly into the fire. The air is pulled under and along the heated shields  44  so that it is preheated before being used in the combustion. 
         [0030]    A cooking grill  50  may be supported directly on rim  8  or on an upright pole  52  that also may support an arm  54  from which one may hang a kettle. Grill  50  can be rotated about pole  52  to remove the cooking surface from above the fire. The handle extends rearwardly from the cooking surface to allow the user to rotate the grill. A winch  56  may be provided to safely change the height of the kettle. Pole  52  may be secured to main body  4 . The winch cable is protected inside a tube that has two openings facing downwardly. 
         [0031]    In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described. Throughout the description and claims of this specification the words “comprise” and “include” as well as variations of those words, such as “comprises,” “includes,” “comprising,” and “including” are not intended to exclude additives, components, integers, or steps.