Patent Application
20110076631
1. Field of the Invention
Embodiments of the present invention relate generally to candles and, more particularly, to a self-extinguishing wick for such candles.
2. Description of the Related Art
Wax-based candles are commonly used for specialized illumination, such as emergency lighting or to contribute to ambience. In addition, candles are used to provide a desirable scent. For any of these applications, an individual candle is typically sized to provide illumination and/or scent for a large number of uses. For example, candles are often sized to have a burn time of dozens of hours or more, but may only be used for a few hours at one time. However, candles commonly known in the art typically are not designed to self-extinguish and, therefore, will continue to burn until completely exhausted unless extinguished by the user. This can make the use of candles inconvenient and, in some cases, a safety hazard. In fact, according to Candle Fires in Residential Structures, a report by U.S. Department of Homeland Security, candles are responsible for an estimated 23,600 residential structure fires each year and cause 1,525 civilian injuries, 165 fatalities, and $390 million in direct property loss.
Accordingly, there is a need in the art for a candle designed to burn for a specified period of time, self-extinguish, and be ready for relighting when next required by the user.
One or more embodiments of the invention provide a self-extinguishing candlewick. The embodiments employ a plurality of flame-extinguishing sleeves positioned on the candlewick. Each flame-extinguishing sleeve is configured to conduct enough heat from a flame disposed at the top of the flame-extinguishing sleeve to form a wax pool that contacts the bottom edge of the flame-extinguishing sleeve.
One advantage of the disclosed invention is that a candle can be used for a predetermined interval and will self-extinguish at the end of said time interval. Another advantage of the disclosed invention is that modification of a conventional wick to incorporate the disclosed invention is relatively simple to implement.
So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
For clarity, identical reference numbers have been used, where applicable, to designate identical elements that are common between figures. It is contemplated that features of one embodiment may be incorporated in other embodiments without further recitation.
Embodiments of the invention contemplate a candlewick with a plurality of flame-extinguishing sleeves disposed thereon that are configured with a length and spacing that cause the candlewick to self-extinguish after a pre-determined time interval. Each flame-extinguishing sleeve is comprised of a non-combustible material that prevents consumption of the candlewick contained therein, and is configured to conduct heat into the body of the candle when a flame is disposed at the top of said sleeve. The wall thickness and the material making up the non-combustible sleeves are selected to provide sufficient heat transfer into the body of the candle to melt the candle base material, e.g., wax, that is in contact with the flame-extinguishing sleeve when a candle flame reaches the top edge of said sleeve. Because of the heat transfer capability of the flame-extinguishing sleeves, a pool of molten candle base material is formed around said sleeve and fuels the candle flame by being drawn up through the wick. As the candle flame continues to burn, the pool of molten candle base material surrounding the flame-extinguishing sleeve is drained and the candle flame burns out. The flame-extinguishing sleeve may then be removed and the candle relit.
Candle body 201 includes any solid candle base material known in the art, such as paraffin-containing wax, that serves as fuel for candle 200 when lit. The term “candle base material” refers to any material that can be used to form a candle. A suitable candle base material may be solid or semi-solid at room temperature, which, upon melting due to exposure to flame 203, provides a liquid fuel source to self-extinguishing wick 202. One common form of candle base material is wax, which usually refers to a substance that is plastic to brittle solid at room temperature and becomes a low viscosity liquid when heated by flame 203. Suitable waxes for forming candle body 201 include any known waxes, including, paraffin wax, microcrystalline wax, beeswax, animal wax, vegetable wax, mineral wax, synthetic wax, and mixtures thereof. In addition to wax, semi-solids (such as petrolatum), synthetic polymers and mixtures of synthetic polymers with one or more organic compounds may be included in the solid candle base material contained in candle body 201. Other candle fuel source components, such as hydrocarbon oil, stearic acid, etc., may be also included in the candle base material.
Self-extinguishing wick 202 includes a wicking element 205, which is made up of an elongated, liquid-wax-absorbing material, such as a conventional braided fiber wick known in the art. The performance-related characteristics of wicking element 205, such as wick size, wick density, and fiber material, depend on a number of factors, including the type of solid candle base material contained in candle body 201, the diameter or width of candle body 201, the desired burn rate and flame height of the candle, etc., and may be selected using methods commonly known in the art. In addition to wicking element 205, self-extinguishing wick 202 includes a plurality of non-combustible sleeves 206 positioned on wicking element 205, as shown. Non-combustible sleeves 206 are separated by a gap 213. In one embodiment, gap 213 is no less than about ⅛ inches, to ensure the flow of molten candle base material to flame 203. The composition of non-combustible sleeves 206 is described below in conjunction with
In addition to protecting wicking element 205 from being consumed by flame 203, non-combustible sleeves 206 are also configured to conduct heat from flame 203 to candle body 201, so that wax pool 204 continues to provide fuel to flame 203 even as flame 203 is displaced further from surface 210. Therefore, each of non-combustible sleeves 206 is configured to transfer sufficient heat from flame 203 to surrounding candle body 201 so that wax pool 204 wets wicking element 205 at the point that wicking element 205 enters bottom opening 220 of exposed non-combustible sleeve 206A. In addition, each of non-combustible sleeves 206 is configured with an inner conduit 221 sized so that wicking element 205 can wick molten candle base material from wax pool 204 at bottom opening 220 to flame 203, i.e., inner conduit 221 is large enough to allow the wicking action of wicking element 205 to keep flame 203 burning. Thus, because of the size of inner conduit 221 and the heat transfer of non-combustible sleeves 206 to surrounding candle body 201, molten candle body material can continue to be drawn to flame 203 through wicking element 205 when flame 203 is disposed on exposed non-combustible sleeve 206A. If such were not the case, liquid fuel will not be available for combustion and flame 203 will extinguish once it is in contact with exposed non-combustible sleeve 206A, leaving exposed non-combustible sleeve 206A almost completely enclosed by candle body 201 and very difficult to remove for subsequent lighting of self-extinguishing candle 200. Consequently, the heat-conducting capability of non-combustible sleeves 206 is considered in embodiments of the invention. To that end, non-combustible sleeves 206 may be comprised of a heat-conducting material and configured with a wall thickness T that enables sufficient heat conducting capability to form wax pool 204 at bottom opening 220, as shown.
To ensure that wax pool 204 is formed around exposed non-combustible sleeve 206A as shown in
As noted above, the predetermined burn time of self-extinguishing candle 200 depends on a number of factors, including length 207 and spacing 208 of non-combustible sleeves 206, as well as on the diameter of self-extinguishing candle 200, the burn rate of wicking element 205, and the candle base material. In one embodiment, self-extinguishing candle 200 is a paraffin-wax candle having a diameter of approximately 3 inches and a pre-waxed wicking element 205 with a diameter of 0.085 inches, and is configured to burn in approximately 2-hour intervals before self-extinguishing. In such an embodiment, non-combustible sleeves 206 are comprised of copper, gap 213 is approximately 3/16 inches, wall thickness T is approximately 0.01 to 0.02 inches, length 207 is approximately ⅜ inches and spacing 208 is approximately 9/16 inches. One of skill in the art, upon reading the disclosure herein, can readily determine the spacing 208 and length 207 of non-combustible sleeves 206 for other configurations of self-extinguishing candle 200 than that described herein.
In order for even burn internals for self-extinguishing candle 200, the positioning of non-combustible sleeves 206 on wicking element 205 should be robust and relatively precise, for example within ± 1/32 inches. In one embodiment, non-combustible sleeves 206 are precisely held in place on wicking element 205 by crimping one end of the sleeve onto wicking element 205. In this way non-combustible sleeves 206 are firmly attached to wicking element 205 and will not slide downward as the wax of wicking element 205 is melted by flame 203. In one embodiment, non-combustible sleeves 206 are crimped at the top edge to facilitate removal from wicking element 205 after self-extinguishing candle 200 has self-extinguished. In another embodiment, other means are used to precisely position and hold in place non-combustible sleeves 206. For example, wicking element 205 may be knotted or include other means for holding non-combustible sleeves 206 in place as desired.
In one embodiment, non-combustible sleeves 206 are substantially cylindrical in shape. However, other configurations of non-combustible sleeves 206 are also contemplated by embodiment of the invention.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
