Patent Application
20080044783
The fundamental concepts and processes for making candles are well known. Candles typically have both utility and ornamental appeal. For example, the warm glow of a candle may provide light and heat. A scented candle may also provide a scent or an aroma and may mask odors, and a candle may generally serve as a decorative device. However, it is desirable to develop new ways of improving the basic candle structure in order to address problems associated with the existing design.
A candle is an instrument that produces light and heat. A small portion of the radiant heat from the candle flame feeds back into the candle and melts the wax to fuel the flame. The candle flame surface itself is the place where fuel (wax vapor) and oxygen mix and burn at high temperatures, radiating heat and light. Heat from the flame is conducted down the wick and melts the wax at the wick base. The melted liquid wax rises up the wick because of capillary action. As the liquid wax nears the flame, the flame's heat causes it to vaporize and combine with oxygen. The vapors are drawn into the flame where they ignite. The heat produced melts more wax.
During combustion, the fuel reacts with oxygen in the air to produce the flame. Carbon dioxide and water are produced and form and reform many carbon rich particles (soot). The soot is drawn up into the top part of the flame where increased temperature causes the carbon to luminesce and burn. Fresh oxygen from the surrounding air is drawn into the flame primarily because of convection currents that are created by the released heat. Hot gases produced during burning are less dense than the cooler surrounding air. They rise upward, and, in doing so, draw the surrounding air, which contains fresh oxygen, into the flame. Solid particles of soot that form in the region between the wick and flame are also carried upward by the convection currents. They ignite and form the bright yellow tip of the flame. The upward flow of hot gases causes the flame to stretch out in a teardrop shape.
In cases in which the combustion of the fuel is incomplete, disadvantages may result. The amount of soot produced can vary greatly depending on the type of candle. One type of candle can produce as much as 100 times more soot than another. Smoke from candles can be a major source of particulate emissions in indoor air. The particulates produced can be deposited in the respiratory tract. These emissions may contain contaminants that can cause a variety of health effects, including mutagenic effects and airborne dermatitis.
Aside from toxic emissions, burning a candle generally results in soot deposits on the surrounding area. Soot particles can penetrate almost all residential air conditioning filters, circulating the particles throughout the space. In addition, soot can deposit on surfaces causing what has been called “ghosting” or “carbon tracking.” Soot tends to accumulate in cool areas, often forming dark areas on baseboards, around air conditioning vents, in or near refrigerators and on wall surfaces over studs. It also is attracted to electrically charged surfaces, including certain plastics and computer screens.
Although complete combustion of a candle is virtually impossible, imperfection in the combustion process can be reduced by designing a candle structure with a composition that allows for the proper air and fuel mixture thereby reducing the amount of smoke and soot released by the candle. Thus, a need exists in the industry for a candle that addresses consumer concerns regarding not only indoor air quality but health hazards associated with candles that produce excessive amounts of smoke and soot.
The present disclosure may be better understood with reference to the following figures. Matching reference numerals designate corresponding parts throughout the figures, and components in the figures are not necessarily to scale.
In one embodiment, a candle structure includes a candle body and a plurality of wicks. The candle body is configured with a top and bottom surface, and an outside wall that tapers substantially inward from the top surface to the bottom surface. The plurality of wicks is configured to supply air through the gaps of standing wicks that protrude from the top surface of the candle structure. The plurality of wicks extends above the body and the wicks are aligned longitudinally. The plurality of wicks is arranged radially to taper outward toward the bottom surface of the candle body.
All such additional systems, devices, methods, features, and advantages are intended to be included within the description and are intended to be protected by the accompanying claims.
As mentioned above the candle structure 100 is configured with a plurality of wicks 120. Wicks 120 are arranged radially and aligned in a longitudinal direction. The upper wick portion 112 extends from the top surface 103 of the candle body 101, and the wicks in this upper portion 112 lean towards the center of the candle. That is, the diameter of the upper wick portion 112 is smaller than the diameter of the lower wick portion.
Once the wicks 120 are ignited, the wax in the wick 120 and the surrounding wax begin to melt. As the wicks 120 burn, they will shorten and/or lean toward one another, which reduces the chance of the flame becoming larger than desired. The spaces 109 between the wicks 120 (near the top surface 103 of the candle body 101) allow ambient air 114 to move freely through. Because the distance between wicks 120 decreases closer to the top surface of the candle body 101, the flame at the bottom of upper wick portion 112 has reduced combustion activity. In leaning toward the center of the candle, the wicks in the upper portion 112 further increase the space between wicks 120 (near the top surface 103 of the candle body 101), allowing for increased air entry at the bottom center of the flame, as compared to straight standing wicks. The movement of air 114 through the upper wick portion 112 increases the temperature in this area, improving the combustion of the fuel vapor.
Smoke is reduced as a result of the inventive radial arrangement of wicks 120 described above, whereby the entire group of wicks 120 has a diameter which decreases toward the top surface 103 of the candle body 101. As the wicks 120 burn, the distance between individual wicks 120 increases. The flame on each indvidual wick 120 thus overlaps less with the other flames, so the overall curtain of flame is thinner and produces less smoke.
An optional feature of the candle body 101 shown in the illustrated embodiment is inside wall 105, which defines a central chamber 130. This central chamber 130 provides several operating advantages, as will now be described.
Once the wicks 120 are ignited, the wax in the wick 120 and the surrounding wax begins to melt. The chamber 130 allows this melted wax (in a liquid or gaseous state) to move towards the bottom 104 of the candle body 101. Reducing the amount of melted wax at the top surface 103 of the candle structure 100 operates to reduce the size of the flame, thus substantially reducing the amount of smoke that is emitted from the candle structure.
After an initial period of burning, melted wax accumulates in chamber 130. As the temperature increases, the melted wax evaporates to gaseous form. Any wax vapor accumulating at the top portion of the chamber 130 that is heavier than air does not escape the chamber 130, but instead serves as a fuel supply to the bottom center of the flame. This increased fuel supply leads to more efficient combustion, which creates a low pressure in the center of the flame that vacuums the surrounding air and evaporated wax toward the center of the flame.
The flow of air 114 toward through the space between wicks 120 and toward the center of the chamber 130 operates to increase fresh air at the bottom of the flame, thus improving the mixture of air-fuel vapor for efficient combustion. This air flow also retains the ignited air-fuel vapor mixture inside and slightly above the chamber 130 for a longer period of time by producing air pressure which is more downward than horizontal with respect to the flame. This extended time operates to promote efficient combustion inside the candle flame, creating a center of low pressure in the lower portion of the flame, which vacuums the flame particles within a sharp flame perimeter. As a result of pressure applied inwardly to the perimeter of the flame, a sharp flame boundary is produced, shielding all soot particles inside of the boundary. This reduces the chance of soot or odor escaping into the surrounding area. Moreover, particles of smoke or odor present in ambient air 114 enter and are contained inside of the flame, until the smoke and odor is reduced or eliminated.
In some embodiments, the chamber 130 is tapered from the top 103 to the bottom 104 of the candle body 101. This tapered shape promotes the flow of wax down toward the bottom 104 of the candle body 101. In addition, the tapered shape of the chamber 130 is capable of holding a much larger volume of wax than could be held by a cylindrically-shaped chamber. The tapered shape of the chamber 130 also promotes the flow of wax and reduces the risk of melted wax being stuck along the inside wall 105.
In the illustrated example embodiment, the peripheral portion 106 of candle body 101 is constructed of a high-melting-point wax, while the intermediate portion 108 of candle body 101 (between the periphery and the center) is constructed of a low-melting-point wax. The size of the peripheral portion 106 is proportional to the diameter of the candle body 101. In an example candle embodiment with a diameter of 2 inches, the peripheral portion 106 is approximately 3 millimeters. The use of high-melting-point wax in the peripheral portion 106 of the candle body 101 slows the melting of the peripheral portion 106 as compared other portions. As a result, the elevation of peripheral portion 106 is higher than the center of the candle (i.e., the top surface 103 slopes from the outer edges, flattening toward the center). This difference in elevation results in air 114 flowing toward the center of the flame at an angle to top surface 103 rather than parallel to top surface 103, which increases combustion efficiency. In contrast, if top surface 103 is flat, the direction of air flow 114 is horizontal, which pushes the flame up and creates more soot.
In some embodiments that include chamber 130, the portion of the candle body 101 that surrounds the wicks 120, near the inner wall 105, is also made of the high-melting-point wax. The use of high-melting-point wax at the inner wall 105 reduces the likelihood of the chamber 130 filling with melted wax. Also, as the low-melting-point wax in the intermediate portion 108 melts faster than the high-melting-point wax around the chamber 130, a raised collar of wax forms to surround the chamber 130. This further decreases the amount of melted wax flows down into the chamber 130.
In one embodiment, the high-melting-point wax has a melting point at or above 60° C., and the low-melting-point wax has a melting point at or below 60° C. In a preferred embodiment, the high-melting point wax has a melting point in the range of 60-90° C., and the low-melting point wax has a melting point in the range of 40-60° C. Stearic acid is one example of a high-melting point wax and lauric acid is one example of a low-melting point wax. In a preferred embodiment, the two waxes belong to the same wax family. In contrast, one wax from an alcohol family and the other wax from an acid or alkane family is not preferred.
An optional feature of the illustrated embodiment of the candle structure 100 is a first circular ring 140 and a heat conductive rod 160. The first circular ring may be made of heat conductive metal such as carbon steel. The ring 140 is configured with equidistant apertures 141 that support each of the wicks 120 longitudinally and radially.
In embodiments without the chamber 130, heat conductive rod 160 extends downward into the central wax portion candle body 101. Rod 160 is heated by the flame, and the heat spreads from the top portion of the rod 160, nearest the flame, to the lower portion of the rod 160. By locating the top portion of rod 160 in the lower portion of the flame, the location of the low-pressure point in the flame is moved downward, improving combustion. (The top portion of the rod 160 should not be extended too high into the flame, since then it does not affect the location of the low-pressure point of the flame). As the heat spreads downwardly, the area of low pressure air associated with the heat also spreads downwardly. However, top surface 103 of candle body 101 remains heated, leading to a depression of melted wax surrounding rod 160, and the wax in this depression evaporates.
In a preferred embodiment of candle structure 100 without a chamber 130, heat conductive rod 160 is made of ceramic. Ceramic is desirable because it has relatively low heat conductivity, and relatively low density/heat capacity.
Rod 160 can be adhesively attached to a plate at the bottom of the candle body 101. In some embodiments, wicks 120 extend to the bottom of candle body 101, and are adhesively attached to a plate at the bottom of the candle body 101.
In embodiments of candle structure 100 which do include a chamber 130, the heat conductive rod 160 extends downward into chamber 130, and heat conductive rod 160 is connected to first circular ring 140 with connecting beams 161. The spaces between connecting beams 161 allow the air/fuel to move through freely.
The rod 160 transfers heat in the flame into chamber 130, creating further reduced pressure in the chamber, and increasing the downward pressure and air movement 114 to the flame for improved combustion. The increased heat from rod 160 into chamber 130 also promotes evaporation of wax in chamber 130, reducing the likelihood that chamber 130 fills with melted wax. In embodiments with a tapered chamber 130, the tapered shape enables the fuel vapor and heavy soot particles to remain inside or in the general area of chamber 130 for an extended period of time. This enables the chemical reaction to progress for a longer period and results in a more complete combustion.
When melted wax begins to accumulate in chamber 130, this wax tends to remove heat from rod 160. A quick accumulation of wax, and a sudden change in the temperature of rod 160, results in an abrupt change in the pressure inside the flame. The accompanying vibration in the flame increases the probability of smoke, until the rod temperature stabilizes again. In a preferred embodiment of candle structure 100 with a chamber 130, rod 160 is made of carbon steel. Carbon steel is relatively dense (and therefore has a relatively large heat capacity) and has an intermediate heat conductivity. These properties reduce any sudden change in temperature of rod 160, and also anchor the location of the low-pressure point downward. In contrast, aluminum is not preferred because its heat conductivity is higher and it has lower density, which cools down the center of flame and melts the wax too fast.
In the illustrated embodiment, candle structure 100 includes a second circular ring 150, which is configured with equidistant apertures 151 that support the wicks 120 longitudinally and radially around the chamber 130. The radial and longitudinal arrangement of wicks allows for the formation of a chamber 130. Second circular ring 150 allows for increased stability of wicks 120 toward bottom surface 104 of candle structure 100. Holding wicks 120 in place increases the probability that substantially all of the wax will burn. In the illustrated embodiment, second circular ring 150 is located near bottom surface 104 of candle structure 100. Second circular ring 150 may be made of metal, such as carbon steel. In some embodiments, first circular ring 140, heat conductive rod 160 and second circular ring 150 are connected to form an assembly.
The layers are arranged so that the top portion 121 of the wick 120′ is thinner (i.e., has a smaller diameter) than the bottom portion 123 of the wick 120′. That is, the top portion 121 includes only central core 122, while bottom portion 123 include central core 122 as well as additional layers such as 124, 126, and/or 128. Viewed another way, the layering of wick 120′ forms a tapered wick 120′.
The location of this thinner diameter wick portion 121, at the top of the wick closest to the flame, allows the flame to burn quickly. As a result, a relatively small amount of wax moves up the wick 120′, leading to a flame with reduced smoke output.
Furthermore, the construction of wick 120′, with concentric layers and a total diameter varying from top 121 to bottom 123, provides an inventive mechanism for self-regulating the part of the wick that is exposed to the flame. The diameter of wick 120′ varies according to the length, and as a result, the diameter of the exposed portion of wick 120′ is proportional to the length of the exposed wick 120′.
When the exposed portion of wick 120′ is relatively long, that exposed portion has an increased diameter, and the flame produced by the wick 120′ is relatively large. This larger flame melts the high-melting-point wax surrounding the wicks 120′ and chamber 130. The excess melted wax flows into the chamber 130, rather than accumulating on wicks 120′ and burning to produce additional smoke. The tapered layers of exposed portion of wick 120′ may limit the wax available in the wick through capillary action. Thus, the exposed outer layers may burn out. Therefore, even if the exposed wick is too high upon ignition, the amount of smoke leaving the flame may be reduced.
When the exposed portion of wick 120′ is relatively short, that exposed portion has a decreased diameter, and the flame produced by the wick 120′ is relatively small. In this case, the high-melting-point wax surrounding the wicks 120′ and chamber 130 does not melt, and as a result the low-melting-point wax in central portion 108 does not melt either. However, the wax on the wicks 120′ and the low-melting-point wax that is adjacent to the wicks does gradually melt. Therefore, less melted wax flows down into the chamber 130, and enough wax accumulates on wicks 120′ to increase burning on the wick itself.
As the wicks 120′ continue to burn, the portion of each tapering wick 120′ that is exposed to the flame has an increasing diameter, and so supplies more wax to the flame. In addition, the diameter of the wick increases at the bottom, so the wick burns for a longer period of time, allowing for a more complete combustion for a relatively large size flame. However, a flame that is too large results in more smoke that is undesirable. In one candle embodiment having a diameter of 2 inches, the diameter of the wick 120′ does not exceed 2 millimeters.
As described above, wick 120′ is tapered, i.e., has a diameter that varies according to the length of the wick 120′. In the illustrated example embodiment, this tapering results from increasing the number of concentric layers as the wick length increases. In other embodiments (not shown), the tapered wick has a single layer with a a diameter that varies with the length of the wick. This embodiment has the same self-regulating advantages described above.
Container 500 may further include an opening 530 at the bottom of the container to promote air flow. The opening 530 is particularly advantageous when used with a candle body 101 having a chamber 130 made of a high-melting-point wax (e.g., caranuba), since the high melting point reduces the amount of melted wax flowing down through chamber 130. The opening 530 may be designed to accommodate the opening of cylinder wick lamps and torches as described in the U.S. patent application Ser. No. 11/621,678 entitled “Lamp with means for controlling air and fuel near the flame”. This allows the candle structure 100 to be used as a replacement for liquid fuel in these lamps and torches.
Container 500 aids in the cooling of wax 106/108 in the candle body 101. When container 500 cools, this reduces the amount of melted wax flowing down along outer wall of container 500. When less wax flows down the sides of container 500, less wax will fill up chamber 130.
Container 500 can also be configured with fins 540 that are capable of dissipating heat. The resulting cool temperature on the outer portion of wax, nearest container 500, leads to a higher elevation at the perimeter of candle body 101, and a lower elevation at the center of candle body 101. This grade promotes the steady and strong flow of air 114 along top surface 103 toward the bottom of the wick 120, instead of experiencing an edge of leveled wax at the container 500 which creates an air turbulence or vortex which resists or slows down the air 114.
Container 500 and candle body 101 have an outside wall 510 which tapers substantially inward from the top surface to the bottom surface, thus avoiding a sharp edge of wax at container 500. This maintains steady flow of air 114. Moreover, the tapered wall makes it easy to place a new candle in container 500 even when some wax residue remains in container 500.
A user of candle structure 100 is able to comfortably touch the sides and bottom of the container 500 since the fins reduce the amount of heat that is transferred to a user's hands. Use of the candle structure 100 inside a metal container 500 may reduce the chance that a user will burn his hands.
While particular embodiments of the candle structure have been disclosed in detail in the foregoing description and figures for purposes of example, those skilled in the art will understand that variations and modifications may be made without departing from the scope of the disclosure. All such variations and modifications are intended to be included within the scope of the present disclosure, as protected by the following claims.
This application is a continuation-in part of application Ser. No. 11/621,678, filed Jan. 10, 2007, which claims the benefit of U.S. Provisional Application No. 60/836,836, filed Aug. 10, 2006, and which is a continuation-in-part of application Ser. No. 10/890,342 and was filed Jul. 13, 2004. Each of these applications is entirely incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60836836 | Aug 2006 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11621678 | Jan 2007 | US |
| Child | 11859151 | Sep 2007 | US |
| Parent | 10890342 | Jul 2004 | US |
| Child | 11859151 | Sep 2007 | US |
