Patent Application
20070065767
This invention relates to a liquid fuel cell and, in particular, to a liquid fuel cell that provides for more rapid and efficient lighting of the burner wick.
Liquid fuel cells which contain a wick-type burner are widely used in restaurants, banquet halls, and the like to provide intimate table lighting for the customers or attendees and for heating or warming food. Many of these fuel cells presently utilize fuels that have a relatively low flash point and are thus highly volatile or become excessively volatile when heated, and can create a fire hazard. In addition, many of the low flash point fuels give off noxious vapors when burned which may be unpleasant when many fuel cells are burning at the same time within an enclosed hall or dining area.
As disclosed in U.S. Pat. No. 4,624,633 to Bandel, fuels have been developed for use in liquid fuel cells that overcome many of the disadvantages associated with the low flash point fuels. The newer fuels also provide extended burning times when compared to more volatile fuels. As a result, the newer fuels have found wide use in smaller size fuel cells that are typically utilized used for heating or warming food or providing intimate table lighting.
The time required to ignite the burner wick of a fuel cell containing a high flash point fuel, however, is considerably longer than that needed to light a fuel cell containing a fuel having a lower flash point. Although the difference in ignition time might be measured in seconds, the total time needed to light all the table lamps in a fair sized restaurant or hall can be considerable. The chance of producing a mislight is also greater due to the longer ignition time.
It is therefore a primary object of the invention to improve liquid fuel cells of the type used for table lighting.
It is a further object of the present invention to improve liquid fuel cells containing a fuel having a high flash point.
It is a still further object of the present invention to shorten the ignition time of a liquid fuel cell that contains a fuel having a high flash point.
Another object of the present invention is to improve the safety of fuel cells by allowing for the convenient use of higher flash point fuels.
These and other objects of the present invention are attained by a liquid fuel cell that includes a canister having a reservoir for holding a quantity of liquid fuel. A burner is mounted upon the canister which contains a vertically disposed wick holding aperture that opens into the fuel reservoir. A wick is mounted in the wick tube which is formed of continuous strands of a wicking material. The wick is doubled over to create a U-shaped crown in its mid-region with the ends of the wick passing down through the wick holding aperture into the reservoirs whereby fuel is drawn into the crown region by capillary action. A number of strands in the crown region are severed to create a small island made up of a series of short bristles at each discontinuation point which provide for a more rapid and efficient ignition of the burner wick.
For a better understanding of these and other objects of the present invention, reference will be made to the following detailed description of the invention which is to be read in association with the accompanying drawings, wherein:
Referring initially to
Because most lamps used for intimate table lighting are relatively small in size, the fuel cell that can be accommodated within the base must be correspondingly small. As a consequence, the amount of fuel that can be stored within the reservoir of this cell is limited. As noted above, fuels having a high flash point above 200° F. have been developed for use in liquid fuel cells for safety reasons. In addition, fuels having a high flash point provide a longer burning time than those having a lower flash point, and are thus better suited for use in smaller fuel cells of the type utilized in lamps for intimate table lighting. The high flash point fuels, however, present certain challenges relative to the lower flash point fuels, one of which being an increased time to light the wick of the burner.
With further reference to
A wick 30 is mounted in the wick holding aperture 28. The wick is fabricated from a number of continuous fiber strands that extend from one end 32 of the wick to the other end 33. In assembly, the wick is doubled over in its mid-region to create a crown 35 and the crown is drawn or otherwise passed upwardly through the wick holding aperture so that it extends some distance above the top of the burner. The two ends of the wick pass downwardly through the aperture into the fuel reservoir and typically are seated along the bottom wall of the reservoir so that both ends of the wick are well inundated within the fuel contained within the reservoir.
The wick may be fabricated of any one of many well-known wicking materials that are capable of drawing fuel from the reservoir into the wick crown region via capillary action. The crown of the wick is typically lighted by placing a flame in close proximity to the crown to heat the fuel to or beyond its flash point. In the case of a wick having unbroken strands, the time required to produce ignition is generally relatively long when compared to the ignition time associated with fuels having lower flash points, the ignition time generally being in the five to six second range in the case of fuels that have a flash point at or above 300° F.
Applicant, through experimentation, has found that the ignition time of a fuel cell of the type herein described can be considerably shortened by producing a discontinuation in a small group of fiber strands within the crown region. Suitable discontinuation of the wick strands can be produced by touching the crown surface with a wire 40 that is heated to a desired temperature by connecting the wire to a suitable source of electric power 42. The heated wire remains in contact with the wick until such time as a small island of short bristles 43 is created in the wire contact region whereupon the heated wire is removed from contact from the surface of the crown. Although a heated wire has been found to work well in practice, the fiber bristles may also be created using a sharp blade, a laser beam, a water knife, or any other suitable cutting instrument capable of severing a small number of strands in the crown region of the wick.
While the present invention has been described with specific reference to a fuel cell for use in a small lamp for providing intimate table lighting, it should be obvious to one skilled in the art that the invention has a broader application for use in any type of fuel cell that employs a fuel having a relatively high flash point.
