Abstract:
The present invention provides methods and apparatus for controlling a flame. One embodiment comprises a reservoir for a flame-fueling liquid, a wick, and a collar surrounding the wick. The first end of the wick is within the reservoir and a flame-bearing end is above the first end. Flame-fueling liquid is supplied to the reservoir and is communicated up the wick to fuel a flame emanating from the flame-bearing end of the wick. The collar is slidable along a vertical axis between a first and second position. In the first position, the top of the collar is located above the flame-bearing end of the wick to block the flow of air from reaching the wick. In the second position, the top of the collar is located below the flame-bearing end of the wick, such that it does not substantially block the flow of air from reaching the wick.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to an apparatus for controlling characteristics of a flame.  
       BACKGROUND  
       [0002]     Some fuels burned by oil lamps produce relatively large amounts of smoke, but are still in use because they have other beneficial properties. For example, citronella oil produces smoke but is useful for repelling insects, such as mosquitoes.  
         [0003]     Air drafts around the flame tend to increase the amount of smoke produced, so some existing lamps provide a shield around the flame to protect from air drafts. However, shielding the flame from air drafts can result in an inadequate air supply to the flame. This inadequate air supply results in incomplete combustion, which has several side effects. One side effect is an increase in the amount of smoke produced. Another side effect is a flame that is non-uniform in color and luminosity, with a bright area at the top of the flame and a dark area in the bottom center.  
         [0004]     A well-known technique to control the height of a flame involves increasing or decreasing the amount of wick exposed to the fuel. For example, an adjusting knob or screws can be used to raise or lower the wick. However, the adjusting knob increases the cost of the lamp, and is often hard to clean. A need therefore exists to address these and other shortcomings in the prior art.  
       SUMMARY  
       [0005]     The present invention is directed to unique methods and apparatus for controlling a flame. One embodiment comprises a reservoir for containing a flame-fueling liquid, a wick, an air channel disposed to supply oxygen to the wick, and a collar surrounding the wick. The first end of the wick is disposed within the reservoir and a second, flame-bearing end is substantially located above the first end. When the flame-fueling liquid is supplied to the reservoir, the flame-fueling liquid is communicated up the wick to fuel a flame emanating from the flame-bearing end of the wick. A first end of the air channel is substantially located near the flame-bearing end of the wick. The collar is slidable along a vertical axis between a first position and a second position. In the first position, a top portion of the collar is located above the flame-bearing end of the wick to substantially block the flow of atmospheric air from reaching the wick. In the second position, the top portion of the collar is located below the flame-bearing end of the wick, such that the collar does not substantially block the flow of atmospheric air from reaching the wick. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0006]      FIG. 1  is an exploded perspective view of one embodiment of an apparatus for controlling the height of a flame.  
         [0007]      FIG. 2  illustrates one embodiment of an adjustment mechanism that can be used with the apparatus for controlling the height of a flame.  
         [0008]      FIGS. 3A and 3B  are cross-sectional side views of another embodiment of the apparatus for controlling the height of a flame, illustrating the flow of air and fuel.  
         [0009]      FIG. 4  is a cross-sectional side view of another embodiment of an apparatus for controlling the height of a flame.  
         [0010]      FIG. 5  is a cross-sectional view of the embodiment of  FIG. 4 , illustrating how the flow of air to the inside portion of the wick  104  is increased.  
         [0011]      FIG. 6A  is a top view of plate  401 .  
         [0012]      FIG. 6B  is a bottom view of reservoir  101 .  
         [0013]      FIG. 6C  is a top view of another embodiment of plate  401 .  
         [0014]      FIG. 7  is a cross-sectional side view of another embodiment of an apparatus for controlling a flame. 
     
    
     DETAILED DESCRIPTION  
       [0015]      FIG. 1  is an exploded perspective view of one embodiment of an apparatus for controlling the height of a flame. The apparatus includes: a fuel reservoir  101 ; a cap  102 ; projections  103 ; a wick  104 ; a sleeve  105 ; and a collar  106 .  
         [0016]     The fuel reservoir  101  contains liquid fuel, for example, liquid paraffin, mineral oil, citronella oil, alcohol, or a variety of other suitable fuels. Cap  102  allows the fuel reservoir  101  to be filled, and also regulates the flow of air into fuel reservoir  101 . Projections  103  extend along the bottom surface of fuel reservoir  101 .  
         [0017]     Wick  104  communicates the liquid fuel from fuel reservoir  101  to a flame-bearing end (see  FIGS. 3A and 3B ) of the wick, where a flame burns. The wick  104  may be made of any suitable material, such as glass fiber or metal mesh, as long as the wick draws liquid fuel from the fuel reservoir. In the embodiment shown in  FIG. 1 , wick  104  is a hollow cylinder. In another embodiment, wick  104  is a solid cylinder.  
         [0018]     Wick  104  fits into sleeve  105 . In one embodiment, the sleeve  105  is shaped to closely conform to wick  104 . Sleeve  105  prevents expansion of the flame to the lower part of wick  104 . In one embodiment, sleeve  105  is made of a heat-conductive material, for example, copper or glass, to lower the viscosity of the liquid fuel.  
         [0019]     Collar  106  is dimensioned to surround a top portion of wick  104 . Collar  106  can be made of any suitable material, for example metal or glass. Collar  106  is slidably adjustable along the vertical axis of the wick, using an adjustment mechanism (shown in  FIG. 2 ). Movement of collar  106  along this axis from bottom to top covers an increasing portion of wick  104 .  
         [0020]      FIG. 2  illustrates one embodiment of an adjustment mechanism that can be used with the apparatus for controlling the height of a flame. In this embodiment, the adjustment mechanism takes the form of a flexible support  201  that fits around sleeve  105 . Flexible support  201 , for example, but not limited to, a rubber ring, is positioned underneath collar  106  to support collar  106 . Because of the dimensions and characteristics of flexible support  201 , it grips sleeve  105  tightly enough to hold collar  106  in the desired position above flexible support  201 , yet loosely enough to allow flexible support  201  to be vertically adjusted to another position.  
         [0021]     In another embodiment (not shown), the adjustment mechanism comprises one or more vertical slots in collar  106 , through which screws protrude to secure collar  106  to sleeve  105 . Upon loosening the screws, the vertical position of collar  106  can be adjusted, and then the screws are fastened again to secure the collar  106 .  
         [0022]     In one embodiment, collar  106  has at least one perforation  202  which allows a limited amount of air to pass through the collar  106  and provide air to the wick  104 . It will be understood that perforations of any shape can be used, for example vertical slits, circular holes, etc.  
         [0023]      FIGS. 3A and 3B  are cross-sectional side views of another embodiment of the apparatus for controlling the height of a flame, illustrating the flow of air and fuel. Air channel  301  has a first end  302  and a second end  303 . When the apparatus rests on a surface, projections  103  create a space underneath the apparatus and allow atmospheric air to enter second end  303  and flow to the first end  302 , which is located near the inner portion of wick  104  when wick  104  is fitted into sleeve  105 . In this embodiment, air channel  301  runs through the center of fuel reservoir  101 , such that first end  302  is located near the center of wick  104  and second end  303  is on the bottom surface of fuel reservoir  101 .  
         [0024]     Sleeve  105  comprises two walls  304 ,  305  which surround and support wick  104 . Wick  104  has a flame-bearing end  306  and a fuel-supplying end  307 . The walls  304 ,  305  provide increased capillary pressure on wick  104 , allowing fuel to be efficiently transported through wick  104 , from its fuel-supplying end  307  to its flame-bearing end  306 . Wick  104  does not extend past sleeve  105 , so that the wick is supplied only by the fuel inside sleeve  105 .  
         [0025]     The fuel flows generally as follows: surface tension of the liquid fuel draws fuel up through the fibers of the wick  104  by capillary action. When the wick  104  burns fuel at its flame bearing end  306 , an equal amount is drawn up the wick  104  from fuel reservoir  101  to replenish the burned fuel. In normal operation, cap  102  is either absent or not tightly closed. Air flows from the atmosphere into fuel reservoir  101  to fill the void left by the burned fuel, so that the pressure outside the sleeve  105  and inside the sleeve  105  is the same. As long as the fuel level inside fuel reservoir is at or above the fuel-supplying end  307  of the wick  104 , fuel is available to be drawn the wick  104 .  
         [0026]     In another mode of operation, cap is tightly closed so that air is unable to flow into fuel reservoir  101  to fill the void left by the burned fuel. In this mode, pressure outside the sleeve is not the same as pressure inside the sleeve  105 , since air channel  301  supplies air inside the sleeve  105  but cap prevents air from flowing into the portion of the fuel reservoir  101  outside the sleeve  1   05 . Because of this difference in pressure, fuel will no longer flow from the portion outside the sleeve  105  to the portion inside the sleeve  105  containing the fuel-supplying end  307  of the wick  104 . When the fuel already present at the fuel-supplying end  307  of the wick  104  is consumed, the wick  104  will no longer be in contact with the fuel inside the sleeve  105 . Since fuel is no longer available to the wick  104 , the flame will diminish in size as the fuel in the wick  104  burns, and then the flame will finally be extinguished.  
         [0027]     The supply of air to the outer portion of wick  104  is influenced by the position of collar  106 . When collar  106  is at a lowered position, as shown in  FIG. 3A , atmospheric air flows freely to the outer portion of wick  104 . Air is also supplied to the inner portion of wick  104  by air channel  301 . This maximal air supply to both inner and outer portions of wick  104  results in a flame with a height  308 . In addition to its large size, the flame produced when the collar  106  is at the lowered position has other desirable characteristics. The flame has uniform color, a sharply defined shape, and slightly reduced luminosity, which makes it less harsh to the eyes. The maximal air supply leads to more complete combustion, which produces very little smoke.  
         [0028]     In contrast,  FIG. 3B  shows the operation of the apparatus with collar  106  at a raised position. Here, the flow of atmospheric air to the outer portion of wick  104  is at least partially blocked by collar  106 , while the inner portion of wick  104  receives a supply of air through air channel  301 . This reduced air supply results in a flame with a height  309  which is less than height  308 , but has the same shape, color and luminosity characteristics as described with regard to  FIG. 3A . In one embodiment, slit  202  (shown in  FIG. 2 ) allows some amount of atmospheric air to flow through collar  106  to wick  104  even when collar  106  is in the raised position.  
         [0029]      FIG. 4  is a cross-sectional side view of another embodiment of an apparatus for controlling the height of a flame. In this embodiment, fuel reservoir  101  sits atop plate  401 , and air flow to the inner portion of the wick (not shown) is controlled by changing the position of fuel reservoir  101  with respect to plate  401 . This embodiment allows the flame height to be controlled without touching the collar  106 , which may be too hot to touch after the flame has burned for some time.  
         [0030]     Two or more projections  103  extend downward from the bottom surface of fuel reservoir  101 . Plate  401  has two or more grooves  402  on its top surface, each of which is configured to receive one of the projections  103  on the bottom surface of fuel reservoir  101 . In one embodiment, plate  401  also has a lip  403  extending upward from the top surface of fuel reservoir  101 , along its periphery. Lip  403  keeps any fuel that spills from reservoir  101  from dripping off the plate  401 , and reduces any air turbulence entering air channel  301 .  
         [0031]     To reduce air flow to the inner portion of the wick  104 , reservoir  101  is positioned atop plate  401  such that projections  103  are received by grooves  402 . The space between fuel reservoir  101  and plate  401  defines a horizontal air channel  404  which is contiguous with air channel  301 . In this configuration, the height of horizontal channel  404  is relatively small, so that airflow into air channel  301  is reduced and the flame is non-uniform in color and luminosity. In one embodiment, plate  401  is covered with rubber or a similar material to increase suction between the two surfaces and thus further reduce the flow of air into air channel  301 .  
         [0032]      FIG. 5  is a cross-sectional view of the embodiment of  FIG. 4 , illustrating how the flow of air to the inside portion of the wick  104  is increased. Reservoir  101  is positioned atop plate  401  such that projections  103  are not received by grooves  402 . In this configuration, the height of horizontal channel  404  is relatively large so that more airflow into air channel  301  is achieved. As a result, the flame is uniform in color and luminosity.  
         [0033]      FIG. 6A  is a top view of plate  401 , showing grooves  402 .  
         [0034]      FIG. 6B  is a bottom view of reservoir  101 , showing projections  103 .  
         [0035]     The example embodiment of  FIGS. 6A &amp; 6B  shows four equidistant grooves  402  and four equidistant projections  103 . However, both the number of projections  103  and their placement can be varied, so long as stability is achieved. In addition, the number of grooves  402  may exceed the number of projections  103 .  
         [0036]      FIG. 6C  is a top view of another embodiment of plate  401 . In this embodiment, plate  401  has second grooves  601  which are adapted to partially receive projections  103 . The depth of each second groove is such that when projections  103  are partially received by the second grooves, the height of horizontal channel  404  is relatively small, allowing a small amount of air to flow into air channel  301 .  
         [0037]     In yet another embodiment (not shown), the depth of groove  402  varies from a first depth, to an intermediate depth, to a second depth. The first depth is such that when projections  103  are received by the grooves  402  at the first depth, the height of horizontal channel  404  is relatively large, allowing a large amount of air to flow into air channel  301 . This produces a tall flame, with a uniform color and slightly reduced luminosity, which is less harsh on the eyes.  
         [0038]     The intermediate depth is such that when projections  103  are received by grooves  402  at the intermediate depth, the height of horizontal channel  404  is intermediate, allowing an intermediate amount of air to flow into air channel  301 . The flame produced is shorter, but still has the uniform color and slightly reduced luminosity characteristics.  
         [0039]     The second depth is such that when projections  103  are received by grooves  402  at the second depth, the height of horizontal channel  404  is relatively small, allowing only a small amount of air to flow into air channel  301 . With the inner air supply greatly reduced, the inner portion of the flame does not burn completely, resulting in a small flame with non-uniform color and luminosity.  
         [0040]      FIG. 7  is a cross-sectional side view of another embodiment of an apparatus for controlling a flame. The apparatus includes: fuel reservoirs  701   a  and  701   b;  caps  702   a  and  702   b ; projections  703 ; plate  707 ; groove  708 ; wicks  760  and  770 .  
         [0041]     The fuel reservoirs  701   a  and  701   b  contain liquid fuel, for example, liquid paraffin, mineral oil, citronella oil, alcohol, or a variety of other suitable fuels. In one embodiment, the fuels contained in fuel reservoirs  701   a  and  701   b  are different, so that the color characteristics of the flames may be different. Projections  703  extend from one surface of fuel reservoir  701   b.    
         [0042]     A fuel-bearing end of each wick  760 ,  770  is in communication with fuel reservoirs  701   a  and  701   b.  Each wick  760 ,  770  thus communicates the liquid fuel from fuel reservoir  701   a ,  701   b  to a flame-bearing end of the wick, where a flame burns. The wicks  770  and  760  may be made of any suitable material, such as glass fiber or metal mesh, as long as the wick draws liquid fuel from the fuel reservoir. In this exemplary embodiment, wicks  770  and  760  are concentrically disposed, and the flame-bearing end of each is disposed near one surface of fuel reservoir  701   a.    
         [0043]     Wick  760  fits into sleeve  740   a  and  740   b.  Wick  770  fits into sleeve  750   a  and  750   b.  The sleeves are shaped to closely conform to the wicks  770  and  760 . Each sleeve  750 ,  740  prevents expansion of the flame to the lower part of the corresponding wick  770 ,  760 . In one embodiment, sleeve  750 ,  740  is made of a heat-conductive material, for example, copper or glass, to lower the viscosity of the liquid fuel. Collar  106  was described above with reference to  FIGS. 1 and 2 .  
         [0044]     Atmospheric air is supplied to the inner portion of wick  770  through a first air channel with a first end  720  located near the hollow center of wick  770 . The second end  730  of the first air channel is located on one surface of reservoir  701   b . Plate  707  and groove  708  were described with reference to  FIGS. 4, 5 ,  6 A-C. When the projections  703  are not received by groove  708 , a horizontal channel is defined between one surface of fuel reservoir  701   b  and the plate  707 . This horizontal channel allows atmospheric air to enter the second end  730  of air channel and flow to the first end  720 , thus supplying air to the inner portion of wick  770 .  
         [0045]     Atmospheric air is supplied to the inner portion of wick  760  through a second air channel, with a first end  780  located between the two flame-bearing ends of the wicks  770  and  760  and a second end located between fuel reservoir  701   a  and fuel reservoir  701   b . Opening  790  can be closed to prevent air from flowing through the second air channel.  
         [0046]     Caps  702   a  and  702   b  allow the fuel reservoirs  701   a ,  701   b  to be filled, and also regulate the flow of air into fuel reservoir,  701   a ,  701   b  in the manner described with reference to  FIG. 3A .  
         [0047]     Each of the wicks  770 ,  760  produces a distinct and separate flame at its flame-bearing end. Flames with different characteristics can be produced by using different fuels in fuel reservoirs  701   a  and  701   b . One characteristic that varies with the type of fuel is the flame color: liquid paraffin produces a yellow flame; citronella oil produces pink; oil blended with copper salts produces green or blue; oil blended with lithium salts produces red.  
         [0048]     The foregoing description has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments discussed, however, were chosen and described to illustrate the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variation are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly and legally entitled.