The present invention relates to dispensers for volatiles such as
scents, insect control active ingredients, and the like. In particular, it relates
to such dispensers that use a fuel burner.
There are a variety of known dispensers for volatiles that employ
heat from a flame or from catalyzed combustion to dispense volatiles from volatile-impregnated
substrates. Citronella candles mix the volatile into the fuel itself. However, this
leaves the candle flame exposed.
U.S. patent 692,075 shows the use of heat from the flame of a conventional
oil lamp to dispense volatile ingredients held exposed to the ambient air on a mesh
mounted on a lamp chimney, above the lamp's flame. The disclosure of this patent
and of all other publications referred to herein are incorporated by reference as
if fully set forth herein. The volatile material being heated by this device is
positioned above the lamp chimney and thus is directly exposed to ambient air currents,
which can cause uneven heating and cooling of the volatile material. The exposed
location of the material being heated also allows it to be touched or disturbed
by a passing child or animal. Furthermore, it is immediately visible to a user so
that charred material can present an unsavory sight.
U.S. patent 143,583 discloses a fumigator in which an alcohol lamp
is placed at the bottom of a metal chimney. A cup to hold an otherwise uncontained
liquid fumigant is suspended within the chimney at its top, and a perforated lid
closes the chimney. The lamp heats the liquid fumigant, and vapor escapes through
the perforations of the lid. Handling the uncontained liquid fumigant and gaining
access to and refilling the cup can be inconvenient and risk spillage.
Petzwinkler, South African patent abstract 94/5537, discloses an oil
lamp equipped with a metal mosquito mat holder that is positioned beside, as opposed
to over, the lamp's flame. Heat radiating from the flame heats a metal holder from
that side of the holder which restrict access into the slot. To enter, a tray must
present a compementary cross-sectional profile to the slot.
Document US-A-4,750,471 concerns a volatile dispenser in which the
volatile carrier is mounted essentially in the ceiling of a heating chamber. Gasses
from a catalytic heater within the heating chamber pass the underside of the volatile
carrier and thereafter pass through openings in the ceiling. There is no flow of
hot gasses over the upper surface of the volatile carrier. An arrangement such as
this suffers from the disadvantage that the upper surface of the volatile carrier
is exposed to outside influences, for example interference by children, or by external
breezes. Also, it is susceptible to preferential volatilization from the underside
of the mat where the hot gasses pass, which can become depleted before the outward-facing
surface looses its active ingredient.
Document FR-A-2 537 394 shows a volatile dispenser in which the volatile
carrier is heated from below by the heat from a gas lamp. The outer surface of the
volatile carrier is completely exposed to the environment.
Document DE 297 20 802 -U1 discloses a lamp containing a candle which
has in an intermediate position up the chimney an annular shelf on which rests a
volatile carrier. Evaporation from the volatile carrier is activated by heating
effect acting on the underside of the shelf. is presented toward the flame. A conventional
mosquito mat is then held vertically on the opposite side of the holder, away from
the flame. By this means, the mat is shielded from direct exposure to the flame
or its gases, albeit it is heated to drive off the volatiles contained in the mat.
The Petzwinkler dispenser provides a visible flame. However, this
dispenser has a mosquito mat holder that holds a mat beside the flame, in open view
of a user, detracting from the pleasing visual effect of the flame itself. Also,
one must remove the dispenser's chimney to gain access to a spent mat to replace
U.S. patents 5,700,430 and 3,778,924 each employ butane as a fuel
for a flame or a catalytic burner, using a replaceable fuel tank. In 5,700,430 a
mosquito mat is laid on top of a metal plate. Heat is conducted from the location
of a flame to the metal plate by means of intervening, heat-conductive parts. In
a subsequent version of the device that otherwise closely corresponded to the embodiment
shown, a butane flame was enclosed within a metal, rectangular, open-ended box.
The box was heated by the flame, and the flame's gases exited an open end of the
box to be vented from the device. A mosquito mat was positioned on top of the box
to receive heat conducted through the metal box from the flame. The butane flame,
heat-conductive parts, and mosquito mat were all held within a protective heat box.
U.S. patent 5,700,430 thus relies on indirect heating. The volatiles
from the hottest places on the mat are released fastest. Consequently, the mat's
volatiles are discharged unevenly, with the possibility that volatiles at locations
remote from the hottest places may never be discharged before the mat's overall
release rate becomes so low as to require replacement of the mat.
In U.S. patent 3,778,924 a mosquito mat is held exposed to the ambient
air on a metal sole plate over a catalytic burner fueled by butane drawn from a
replaceable, pressurized tank. However, the mat is not enclosed in a heating chamber.
Other patents disclose assemblies that rely on an electrical heater
(as distinguished from a fuel burning heater) to heat the volatile carrier.
See e.g. U.S. patents 2,513,919, 2,942,090, 4,849,181 and 5,111,477.
This restricts the portability of the device (it cannot easily be used at camping
or picnic sites which do not have electrical power).
U.S. patent 5,722,199 discloses a flea trap (without a volatile heater)
having a removable tray that slides into a slot in the flea trap. The slot has keying
There are also a number of other known insect repellent/killing devices
which provide a heat source under a platform designed to support a pad that has
been impregnated with the insect control active ingredient. Some use a liquid fuel
such as alcohol that is burned in an open flame, or directed to a catalyst mesh
where it combusts.
In some cases the platform is an open grid. In others it is a flat
metal plate heated from beneath. Some of these systems also provide a separate grid
structure which snaps or swings over the carrier for restricting access to the heated
mat during operation. These systems typically do not provide a light source through
transparent sides of a heating chamber (e.g. they are designed purely for insect
It can therefore be seen that there is a need for an improved heated
BRIEF SUMMARY OF THE INVENTION
The invention provides a heated volatile dispenser for dispensing
volatile ingredients from a volatile carrier. "Volatile ingredients" include (without
limitation) perfumes and other air quality modifying materials, as well as insect
control ingredients. "Insect" includes arachnids and other similar, small animals
commonly controlled in conjunction with insects. "Insect control ingredients" are
defined as including (without limitation) insecticides, repellents, and other development
or behavior modifying materials. One highly preferred insect control agent is d-cis/trans
A "volatile carrier" is a material or structure for holding a volatile
ingredient for dispensing. "Mats" are one common type of volatile carrier often
used with insect control ingredients and are defined as including (without limitation)
woven, felted, or otherwise formed fibrous or cellulose materials; as well as molded,
extruded, cast, or otherwise formed polymeric, ceramic, and clay materials, together
with other convenient materials loaded with volatile ingredients, whether by impregnation,
printing, or otherwise. Volatile carriers can also be metal or plastic cups holding
a volatilizable gel; cups holding a gel, powder, or liquid retained in the cup by
a volatile-permeable membrane; or any other convenient means for holding a material
to be volatilized by the application of heat. However, uncontained liquids or powders,
together with liquids or powders held in open cups or similar containers, are excluded
from the term "volatile carrier," as used herein.
In one form, the heated volatile dispenser of the invention has an
enclosed heating chamber having chamber walls. The heating chamber preferably also
has a ceiling, although a heating chamber will be understood as being "enclosed"
if it has walls, either an open top or a ceiling, and either a closed or an open
bottom. If the heating chamber has a ceiling, the heating chamber also has exit
vents in the ceiling or chamber walls or both that communicate between the interior
of the heating chamber and the outside air. The exit vents are holes, slots, or
other openings that function as vents. Particularly preferred are permanently enclosed
structures with ceilings.
The dispenser also has a heat source that preferably is a fuel burner.
The fuel burner can be a candle, a burner using a solidified combustible liquid
such as conventional gelled alcohol, a burnable solid, a pressurized gas burner,
a wick that is fueled with a combustible liquid, a catalytic heater burning a gas
or liquid fuel, or any other convenient means for combusting a fuel.
The heated volatile dispenser is equipped to hold a volatile carrier
contained within the heating chamber. It is possible to design a volatile carrier
that requires no separate, specific structure in the dispenser to hold it within
the heating chamber--for example, a volatile carrier equipped with side hooks or
arms that hook over the tops of the heating chamber walls, allowing the rest of
the volatile carrier to hang downwardly within the heating chamber. Such side hooks,
together with the surface that supports them, would constitute a carrier holder.
However, it is preferred that the heated volatile dispenser include an additional
structure that serves as a carrier holder that is positioned to receive and hold
a volatile carrier at a location above the fuel burner and contained within the
heating chamber. An air-flow path is provided to guide hot gases, rising from the
fuel burner by convection, past the location where a volatile carrier can be held,
whether or not in a separate carrier holder, to heat the volatile carrier. The air-flow
path is preferably defined, at least in part, by internal surfaces of the heating
chamber walls. Heating is accomplished by the direct exposure of the volatile carrier
to gases heated by the fuel burner. Preferably, the hot gases include combustion
products from the fuel burner. The air-flow path then directs the hot gases through
the open top of an open-topped heating chamber or through the exit vents, if a ceiling
is present, to escape from the dispenser. As the volatile carrier is heated by the
gases, volatile material is released and is carried out of the dispenser with the
escaping hot gases.
As indicated above, the term "carrier holder" should be understood
very broadly as including any structure that provides for positioning a volatile
carrier within the air-flow path, within the heating chamber. In some embodiments,
very little separate structure is actually required. For example, in one form, the
carrier holder can be a slot in the heating chamber wall through which a volatile
carrier is inserted, with the slot being a sufficiently snug fit for the volatile
carrier that the parts of the volatile carrier projecting within the heating chamber
are held in position by the snug contact between the slot and the volatile carrier.
Also, a possible carrier holder can be a slot in the heating chamber ceiling, for
use with a volatile carrier that is designed to be inserted downwardly through the
slot and to hang from the edges of the slot from side tabs, a handle, or other parts
of the volatile carrier that, because of their size or geometry, remain outside
of the heating chamber, resting on outer surfaces of the ceiling.
Alternatively, the carrier holder may be an essentially open, either
vertically disposed rack that leaves a mat or other volatile carrier held in the
carrier holder directly exposed to hot gases rising in a convective flow from beneath.
Depending on the materials chosen and the volatile carrier temperatures
desired, it is also possible to include a baffle spaced from and preferably located
beneath the carrier holder and interposed between the fuel burner and a volatile
carrier being held in the carrier holder. The baffle functions in part to mix hot
gases from the fuel burner with air in the heating chamber prior to their reaching
the volatile carrier. The result is believed to be a reduction of the tendency for
a hot spot to form at a point on the volatile carrier directly above the fuel burner.
Instead, the baffle causes a more even heating of the volatile carrier, whether
the volatile carrier is heated solely by direct exposure to the hot gases or by
a combination of direct exposure to hot gases and heat conducted through a sole
The baffle can also function to more evenly distribute heat in another
way. If the baffle is so located as to be heated by hot gases contacting the baffle
from below, and if the carrier holder is spaced above the baffle, then the hot baffle
serves as a radiant heater, supplementing heat delivered by a volatile carrier's
direct contact with the hot gas flow by providing broadly distributed radiant heat
to the volatile carrier.
Alternatively, the carrier holder can be in the form of an oven located
within the heating chamber. "Oven" shall mean any substantially enclosed sub-chamber
located within the heating chamber walls and made, preferably, of a heat-conductive
material. The oven has oven walls and is positioned within the air-flow path. By
this arrangement, the oven is heated by hot gases rising from the fuel burner. The
oven holds a volatile carrier within the oven to receive heat radiating inwardly
from the oven walls, an arrangement that provides for a more even heating of the
volatile carrier. The oven preferably has openings sufficient to admit hot gases
rising from the fuel burner so that they may directly contact the volatile carrier,
and in any event has vents to allow volatile materials released from the volatile
carrier to escape from the oven.
Although the fuel burner can be located beneath a heating chamber
that has an open bottom, preferably the fuel burner is contained within the heating
chamber itself. This arrangement contributes to the control and isolation of the
convective flow of hot gases rising from the fuel burner and can also provide containment
and protection for a burning flame. Thus, the walls of the heating chamber above
the fuel burner can define the air flow path and limit the effects of breezes and
other air movement external to the volatile dispenser.
It is sometimes desirable to reduce the temperature of the hot gases
prior to their acting to heat the volatile carrier. To help achieve this, the heating
chamber walls can be equipped with cooling vents communicating with the air outside
of the heating chamber to cause unheated air to be drawn into the heating chamber
by the passing flow of heated gases, to mix with and partially cool the hot gases
from the fuel burner prior to their reaching the carrier holder. The cooling vents
can be provided at any point in the air flow path, but preferably they are located
at a point in the chamber walls at or above the level of the fuel burner but beneath
the level at which a volatile carrier is held.
Although the fuel burner may burn fuel catalytically or otherwise
without a flame and still fall within the breadth and scope of the invention, it
is highly preferred that the fuel burner support a luminous flame positioned within
the heating chamber and that the heating chamber walls include a light-transmitting
portion, whether clear or translucent, that allows light from the flame to be visible
to a user of the dispenser. This provides a ready means for a user to confirm that
the fuel burner has been lit and continues to burn, and it also provides a use-up
cue for the fuel. But the flame also provides light and aesthetic appeal, in much
the same way that a citronella candle is valued in great part for its light. However,
it is preferred that the carrier holder be positioned within a portion of the heating
chamber whose walls are opaque or translucent so that the holder is at least not
clearly visible through the chamber side walls. Walls will be deemed "visually obstructed"
if they are opaque, translucent, or otherwise prevent the observation of distinct
outlines of objects viewed therethrough.
The mats or other volatile carriers become exhausted and are designed
to be replaced. To achieve this, preferably an insert slot communicates between
the interior of the heating chamber and the exterior of the heated volatile dispenser,
so that a fresh volatile carrier can be inserted through the insert slot to be held
by the carrier holder. The insert slot can be in either the chamber walls or the
ceiling of the heating chamber.
It can be important to prevent the use of a volatile carrier not intended
for use with a particular volatile dispenser, to not mistakenly use, for example,
a volatile carrier loaded with insecticide in a dispenser intended to supply perfume
for indoor use. Therefore, it is preferred that the insert slot include keying structures
that impart a cross-sectional profile to the insert slot that so restricts access
thereto as to prevent the insertion of any volatile carrier not capable of presenting
a non-interfering cross-sectional profile to the cross-sectional profile of the
insert slot. This makes it easier to ensure that the only volatile carriers that
will fit a given dispenser are those that are appropriate to a particular purpose
or that are designed for use with the specific temperatures generated by the volatile
dispenser. Also, the keying structures can be used to require that the volatile
carrier be insertable only with a pre-determined side up or down. This can be important
if the volatile carrier is, by way of example only, a gel cup that must be inserted
so as to open upwardly. As examples, the keying structures can define a cross-sectional
profile that includes either or both of angularly intersecting and curved sections.
Volatile carriers have a section treated or loaded (e.g. paper impregnated
with insecticide) with the volatile material to be dispensed, and this section may
itself be formed with a functionally required cross-sectional profile such as those
Alternatively, the volatile carrier can include a handle in addition to a volatile-treated
section, and the keying structures of the insert slot can be formed to present a
non-interfering cross-sectional profile with respect to at least a portion of the
volatile carrier and an interfering cross-sectional profile with respect to the
handle for the volatile carrier.
In one embodiment, the heated volatile dispenser includes a fuel tank,
containing fuel under pressure, and a fuel transfer route by which fuel can be transferred
to the fuel burner in controlled amounts. Valves, constricted flow paths, wicks,
pressure step-down controllers, or any other means may be used to control the delivery
of pressurized fuel to the fuel burner in an amount sufficient to maintain combustion
at a convenient level, and a variable valve may be used to allow a user to adjust
the amount of fuel being burned. Preferably the fuel tank is replaceably removable.
Ideally, the fuel tank contains fuel that burns as a pressurized gas, even though
it may be a liquid at the tank pressures selected. Preferred gases include a gas
selected from the group consisting of butane, isobutane, propane, compressed natural
gas, and mixtures thereof.
An alternative and presently most preferred embodiment of the heated
volatile dispenser of the invention is designed for use with a volatile carrier
having a volatile-loaded section having a linearly extended volatile-releasing surface.
The heated volatile dispenser includes a heat source that preferably is a fuel burner,
the heat source generating a convective flow of hot gases. The heated volatile dispenser
is used with a volatile carrier designed to hang or otherwise be positioned within
the flow of hot gases in an orientation such that hot gas sweeps across the volatile-releasing
surface, in a generally vertical direction but, in any event, in a direction generally
parallel to the direction of linear extension of the volatile-releasing surface
to release volatile therefrom. Preferably, the heated volatile dispenser includes
a carrier holder that holds the volatile carrier within the flow of hot gases in
that orientation. The heated volatile dispenser can also have any or all of the
other features disclosed, above, with respect to the other embodiments, so long
as those features are not inconsistent with the orientation of the volatile carrier
A volatile carrier is used that has at least two volatile-releasing
surfaces. The volatile carrier is then so designed, or the carrier holder, if present,
then is designed, to hold the volatile carrier in an orientation such that hot gas
sweeps across at least two of the volatile-releasing surfaces at the same time.
The volatile carrier has front and back volatile-releasing surfaces. By way of example,
only, a conventional mosquito mat has front and back surfaces, and the volatile
carrier or the carrier holder can be designed such that the mat is held edge-on
with respect to the flow of hot gases so that gas sweeps across both surfaces of
the mat at the same time.
This arrangement has important advantages for the control of temperature
across the volatile-releasing surfaces of the volatile carrier. The convective flow
of hot gases above a sufficiently hot heater, and especially above a fuel burner
that produces both heated air and gaseous combustion products, is fast compared
to the conductive flow of heat through metal or other solid materials. Consequently,
it is believed that the temperature of the hot gases does not drop much as the gases
pass over the volatile-releasing surfaces. As a result, the volatile carrier is
more evenly heated across its linear expanse so that volatiles are released more
uniformly from the entire volatile-releasing surface. When the rate of volatile
release from the volatile carrier drops sufficiently low that a fresh carrier is
needed, the volatile from the exhausted carrier will have been more completely used
than is the case when distinct, hotter and cooler regions are formed across the
When the heated volatile dispenser includes a carrier holder that
is designed to be used with a volatile carrier having a linearly extended, volatile
treated section having a leading edge to be presented toward the flow of hot gases,
the carrier holder should preferably include a heat resistant edge guard that extends
along the leading edge of a volatile carrier held in the carrier holder. The edge
guard preferably extends the entire length of the leading edge. Alternatively, the
edge guard can extend to protect only a portion of the leading edge that is exposed
to the hottest area within the flow of hot gases, typically located at the center
of the leading edge. An edge guard or a material will be understood to be "heat
resistant" if it does not burn, char, or deform when subjected to the temperatures
present at its location within a heated volatile dispenser when that dispenser is
The edge guard protects the leading edge of the volatile carrier from
heat directly radiating from a fuel burner and from the direct, edgeward impact
of the flow of hot gases. Also, when the volatile carrier has at least two and preferably
front and back volatile-releasing surfaces, the edge guard helps to split the flow
of hot gases to direct the gases across the volatile-releasing surfaces. Either
additionally or alternatively, a volatile carrier of the invention intended for
such an edge-on orientation can be equipped with a carrier edge guard formed on
or attached to the leading edge of the volatile carrier, itself. It is preferred
that the edge guard, whether a part of the heated volatile dispenser or attached
to the leading edge of the volatile carrier, include deflector vanes extending sidewardly
with respect to the direction of linear extension of the volatile carrier's treated
section to disrupt and mix the flow of hot gases before the gases contact the treated
In the presently most preferred embodiment of the invention, fuel
burner is ventilated from beneath via a circumferentially extending open space surrounding
the fuel burner, which space is vented to the ambient air. When a base is provided,
located beneath the heating chamber, the base has a ventilation opening through
which ambient air can pass to continue upwardly through the heating chamber. The
fuel burner is so supported by the base in relation to the ventilation opening that
the fuel burner is circumferentially ventilated from beneath. The preferred fuel
burner in this arrangement employs a candle and preferably includes a candle cup
having cup walls and a downwardly opening socket. The base then includes an attachment
post to engage the socket and thus hold the candle cup. The heating chamber can
include a light-transmitting chimney attached to the base.
Although the volatile dispenser of the invention (and preferably the
embodiment just described) can be made with a base that can rest in a stable fashion
on a flat supporting surface, it is also possible to provide for hanging the dispenser
from a hook or other supporting structure. In that arrangement, the heated volatile
dispenser includes a hanger by which the dispenser may be suspended from above.
It is also then possible to so shape the underside of the base as to prevent the
dispenser being supported in an upright orientation on a flat surface.
It is beneficial to provide for a candle that self-extinguishes, should
the volatile dispenser tip over. To achieve this result, the fuel burner includes
a candle contained within a candle cup, the candle cup having a floor and upright
walls terminating in an open top and being made of a heat resistant material. The
candle cup is fixedly positioned within the heating chamber, so that, should the
volatile dispenser tip sidewardly while the candle is burning, the candle's heat
contained within the candle cup will melt at least a portion of the candle's wax,
allowing it to flow from the open top to starve the candle's wick of fuel, causing
the candle to self-extinguish.
The invention also provides a method in accordance with claim 23.
A preferred method of the invention is disclosed for dispensing a
volatile material from a volatile carrier having a volatile-loaded section having
a linearly extended, volatile-releasing surface. The method includes the steps of
providing a heat source, preferably a fuel burner, generating a flow of hot gases
and holding the volatile carrier within the flow of hot gases in an orientation
such that hot gas sweeps across the volatile-releasing surface, preferably in a
direction generally parallel to the direction of linear extension of the volatile-releasing
surface. The volatile carrier has both front and back volatile-releasing surfaces,
and the step of holding the volatile carrier within the hot gases includes holding
the volatile carrier in an orientation such that hot gas sweeps across both the
front and back volatile releasing surfaces at the same time.
The invention also includes a volatile-dispensing volatile carrier
suitable for use with a heated volatile dispenser having an insert slot through
which the volatile carrier must be inserted for use, the insert slot having keying
structures that impart a cross-sectional profile to the insert slot that departs
from a straight cross-sectional profile and that so restricts access thereto as
to prevent the insertion of any volatile carrier not capable of presenting a complementary
cross-sectional profile. The volatile carrier of the invention includes a treated
section having a cross-sectional profile complementary to that of the insert slot.
The volatile. carrier also can have a handle having a cross-sectional profile that
prevents the handle's entrance into the insert slot. Preferably the cross-sectional
profile of the treated section includes curved or angularly intersecting sections,
the latter including (without limitation) slots, prongs, ribs, and the like. Combinations
of curved and angularly intersecting sections may also be used. Preferably the volatile
carrier is a mat.
A kit is also disclosed for use with a heated volatile dispenser that
employs a fuel burner to provide hot gases to heat and release a volatile material
from a volatile carrier. The kit includes at least one volatile carrier, each volatile
carrier bearing a selected amount of the volatile to be dispensed, and at least
one fuel source for the fuel burner. The amount of fuel in a selected number of
fuel sources is selected to be exhausted at substantially the same time that a selected
amount of the volatile has been exhausted from at least one of the volatile carriers
of the kit, whereby the exhausting of fuel provides a use up cue indicating that
the selected amount of volatile has also been exhausted. Volatile is defined as
being "exhausted" if the volatile has been released to the point that additional
release of volatile is reduced to an amount or rate such that the desired effect
to be accomplished by the volatile release is no longer achieved. A fuel source
is defined as being exhausted at "substantially the same time" as the volatile is
exhausted if the fuel burner extinguishes for lack of fuel when the volatile is
either exhausted or when only that amount of volatile remains that a user is willing
Preferably, the kit includes only paired single fuel sources and single
volatile carriers, with the volatile of a single volatile carrier being exhausted
by the hot gases generated by the use of a single fuel source. However, it is also
possible to achieve this benefit by requiring that two or more fuel sources be used
before the volatile of a given carrier is exhausted. The goal is to have the easily
perceived consumption of fuel serve as a use-up cue for the less easily detected
consumption of the volatile of a volatile carrier. Preferably, the fuel source is
Preferably, the volatile carriers of the kit have a treated section
that is linearly extended and holds volatile material to be dispensed, and the amount
of volatile material held by a volatile carrier is selected to be exhausted by the
hot gases generated by the use of a single fuel source when the volatile carrier
is so positioned that the hot gases sweep over the linearly extended section. In
an embodiment, the treated section has two sides and the amount of volatile material
held by a volatile carrier is selected to be exhausted by the hot gases generated
by the use of a single fuel source when the volatile carrier is so positioned that
the hot gases sweep over the two sides of the linearly extended section. Ideally,
the treated section has a front and a back and the volatile carrier has a leading
edge. The amount of volatile material held by the treated section is selected to
be exhausted by exposure to a flow of hot gases generated by the use of a single
fuel source when the volatile carrier is so positioned that the flow of hot gases
divides. with hot gases flowing to either side of the leading edge, to sweep over
the sides of the treated section.
A preferred method of dispensing a volatile material from a volatile
carrier includes a first step of providing a fuel source for the fuel burner having
an amount of fuel selected to become exhausted (causing the fuel burner to extinguish)
at the same time that the volatile of the volatile carrier is substantially exhausted.
The effect of this step is to cause the extinguishing of the fuel burner to provide
a use-up cue for the substantial exhaustion of volatile from the volatile carrier.
The second step of the method is to light the fuel burner, with the volatile carrier
in place. Preferably, the heated volatile dispenser used is of the sort in which
fuel bums as a flame visible to a user of the dispenser. In that event, the steps
of providing the fuel source and lighting the fuel burner include providing a visually
observable use-up cue for the substantial exhaustion of volatile from the volatile
Also provided is a fuel burner useable with a heated volatile dispenser
that has an attachment post for holding the fuel burner. The fuel burner includes
a candle held within a open-topped candle cup. The candle cup has a cup floor, cup
walls, and a downwardly opening socket extending downwardly beneath the cup floor
and engageable on the attachment post. At least one cup support member extends downwardly
beneath the cup floor at least as far as the socket extends. The at least one cup
support member is at a location sufficiently remote from the socket and cumulatively
extends circumferentially sufficiently to provide a stable support such that the
candle cup can sit on a flat surface without tipping. Preferably, the cup support
member extends around the entire margin of the cup floor. This arrangement is generally
convenient for a user, but it is also important in the manufacture of the fuel burner
in that it allows the candle cup to sit in a stable fashion on a flat conveyer belt
or other materials handling surface. '
BRIEF DESCRIPTION OF THE DRAWINGS
DETAILED DESCRIPTION OF THE INVENTION
- Fig. 1 is a perspective view of a heated volatile dispenser which uses a gas
- Fig. 2 is a top plan view thereof;
- Fig. 3 is a vertical cross sectional view of the Fig. 1 arrangement;
- Fig. 4 is an enlarged cross sectional view of the shut-off valve portion of
- Fig. 5 is a perspective view of another arrangement which uses a candle for
- Fig. 6 is a cross sectional view of the arrangement of Fig. 5 taken along line
6-6 of Fig. 5;
- Fig. 7 is a cross sectional view of the upper portion of a heated volatile dispenser
like that of Fig. 1 or Fig. 5, albeit showing an alternative carrier holder having
a conductive sole plate;
- Fig. 8 is a cross sectional view of the upper portion of a heated volatile dispenser
like that of Fig. 1 or Fig. 5, albeit showing another alternative volatile carrier
holder in the form of an oven;
- Fig. 9 is a cross sectional view of the upper portion of a heated volatile dispenser
like that of Fig. 1 or Fig. 5, but in accordance with the present invention wherein
a volatile carrier holder holds a volatile carrier in a vertical orientation;
- Fig. 10 is a partial cross sectional view of the heated volatile dispenser of
Fig. 9, albeit taken at an angle which is rotated 90 degrees relative to that of
- Fig. 11 is a perspective view of another volatile carrier of the invention having
an edge guard;
- Fig. 12 is a cross sectional view generally corresponding to Fig. 9, but showing
how surfaces of the heating chamber ceiling can serve as the carrier holder;
- Fig. 13 is a lower frontal perspective view of a form of volatile carrier that
can be used when the top of the Fig. 9 embodiment is provided with the Fig. 15 inlet
- Fig. 14 is a lower frontal perspective view of another form of volatile carrier
that can be used when the top of the Fig. 9 embodiment is provided with a wavy curve
inlet slot; and
- Fig. 15 is a top plan view of a dispenser having a ceiling with an insert slot
suitable to receive the Fig. 13 volatile carrier.
- Fig. 16 is a perspective view of an alternative embodiment of the heated volatile
dispenser of the invention, including a candle and a volatile carrier, with portions
of the chimney broken away.
- Fig. 17 is a perspective view of the base of the heated volatile dispenser of
Fig. 16, with the chimney removed and without a candle.
- Fig. 18 is a cross sectional view of the heated volatile dispenser of Fig. 16,
taken along sections lines 18--18 of Fig. 16.
- Fig. 19 is a perspective view from beneath of a candle for use in the invention.
- Fig. 20 is a cross sectional view of the candle of Fig., 19, taken along section
lines 20--20 of Fig. 19.
- Fig. 21 is a cross sectional view corresponding to that of Fig. 18 but with
the heated volatile dispenser shown tipped on its side on a supporting surface.
- Fig. 22 is a side elevation view of an alternative embodiment of the heated
volatile dispenser of the invention.
- Fig. 23 is a cross sectional view of the heated volatile dispenser of Fig. 22,
the view otherwise generally corresponding to the view of Fig. 18.
We turn first to the comparative example shown in Figs. 1-4. A dispenser,
generally 10, encloses an internal heating chamber 12 having chamber side walls
13. There is also a chamber ceiling 14 that has exit vents 15.
The assembly includes a fuel burner 20. Fuel is supplied from a pressurized
gas fuel source 101 through a fuel transfer route 102 by which fuel can be transferred
to the fuel burner 20 in controlled amounts. Various types of valving and ignition
systems can be used for this purpose (see e.g. U.S. patent 5,700,430).
However, another option is depicted in Figs. 1 and 4. Rotation of
outer ring 107 will cause rotation of inner ring 106, thereby rotating a lower extension
therefrom, which acts as a valve to control the amount of fuel being provided. Various
known ignition systems, not shown, can be incorporated as well.
The dispenser also includes a cellulosic mat-like carrier 22, preferably
impregnated with an insect control ingredient, preferably an insecticide. The carrier
is slid through insert slot 41 in the outer housing and rests on carrier holder
23. The carrier holder 23 is located above the fuel burner and within the heating
The walls of the chamber provide an air-flow path to guide hot gases
from the fuel burner 20 past the carrier holder 23 to heat the carrier 22. This
provides the direct exposure of the volatile carrier to the gases created by the
Preferably there is also a baffle 25 interposed between the fuel burner
20 and the carrier 22. This creates turbulence in the region 18 so as to better
mix gases prior to their reaching the carrier 22. The baffle 25 also acts as a radiant
heater beneath the carrier holder 23.
There is a light transmitting transparent or translucent plastic portion
28 which allows light from the flame 27 to be visible to a user of the dispenser.
Thus, the dispenser both dispenses the volatile and provides a light function. In
this form, the fuel burner 20 is preferably also within the heating chamber 12.
There may also be a cooling vent 40 that permits air outside of the
heating chamber 12 to enter the heating chamber and partially cool the hot gases
prior to their reaching the carrier. Vent 40 is located above the level of the fuel
The carrier holder 23 is positioned within a part 29 of the heating
chamber 12 that is visually obstructed in that it is either opaque or translucent
such that the carrier holder is not clearly visible through the chamber side walls.
It is preferred that the wall portions 28 and 29 be permanently assembled together
(e.g. sonic welded) so that the heating chamber remains continuously enclosed.
Turning next to the comparative example of Figs. 5-7 (generally 60),
the fuel burner is now the wick of wax candle 30. There is a housing 65 with a cap
64 having vents 66. Side walls 63 help define the heating chamber. The volatile
carrier 22 is inserted through slot 61 and in this case held on a sole plate 73
that is solid except for having spider leg radially peripheral attachments 71. The
housing 65 can be lifted off the candle 30, the candle can be lit with a match,
and the housing can be replaced to its Fig. 5 position.
In either case (the Fig. 1 or the Fig. 5 arrangement), the gases flow
upward and ultimately around the volatile carrier before exiting. The gases will
be sufficiently dispersed so as to provide desirable heating. The same flame which
provides the heat source will also provide the light source.
Turning now to Fig. 7, another version of the sole plate 74 has its
ends alternatively supported in side brackets 75. The design is otherwise similar
to the embodiment of Fig. 5.
As shown in Fig. 8, there is provided an oven (generally 76). It has
a side slot 77 that is aligned with the outer insert slot so as to permit the carrier
22 to be inserted not only through the outer insert slot, but also in the oven.
In use, the oven 76 has a sufficient heat capacity that it serves to maintain a
more constant temperature within the oven than might otherwise be experienced at
that location in the flow of hot, gaseous gases if, for example, the heat source
were a flickering flame. Bottom hole 79 permits gases to readily enter the oven.
Top hole 81 permits them to readily exit.
Figs. 9 and 10 depict embodiments of the invention. This arrangement
has a generally vertically positioned carrier 78 inserted through an insert
slot 42 and held by a carrier holder 82 having a protective guard 83 with side walls
95. This system has the advantage of exposing both sides of the carrier to
roughly equivalent heat. The hot gas sweeps across the volatile-releasing surface
in a direction generally parallel to the direction of linear extension of the volatile-releasing
surfaces of the volatile carrier 22. Yet the downward edge of the volatile carrier
is protected by protective guard 83 against undesirable overheating.
As shown in Fig. 11, the carrier 78 can be provided with a handle
93 and a heat resistant guard 86 positioned on a leading edge so as to be able to
split the flow of hot gases when the carrier is held within the flow of hot gases.
This again protects the treated section from edgeward impact of the hot gases. The
guard preferably also has deflector vanes 96 extending sidewardly.
In these vertical forms, the carrier 78 is linearly extended and treated
on both front and back sides.
As best seen in Fig. 15, an insert slot 98 that is not simply
rectangular can be formed in the ceiling of the dispenser. When used with a carrier
such as carrier 88 of Fig. 13, the edge 91 presents a non-interfering cross-sectional
profile with respect to the insert slot 98, while still allowing some venting via
exits 99. The opposite surface from surface 92 shown presents an interfering cross-sectional
profile preventing the handle 94 from falling through the insert slot.
If instead the carrier is carrier 89 as shown in Fig. 14, the Fig.
15 insert slot would then need to be a wavy line inlet. Thus, by using either form,
the proper direction of the carrier can be controlled, and the public can be prevented
from inserting mats into a given system that are not customized for use with that
In essence, this is a keying structure in which the cross-sectional
profile of the insert slot must match with the cross-sectional profile of an inward
end of the volatile carrier. The profile should depart from a rectangular slot,
preferably using angularly intersecting and/or curved sections. Moreover, such a
system is particularly useful in connection with horizontally extending carriers
that have only one side treated with active.
An alternative and presently most preferred embodiment of the heated
volatile dispenser of the invention is shown generally at in Fig. 16. The dispenser
110 has a base 112 that supports a removable chimney 114, the chimney attaching
to the base with locking tabs 113 formed on the lower edge of the chimney that mate
with locking slots 115 formed in the base. The chimney can be made of glass or,
preferably, a heat-resistive clear or (preferably) translucent plastic. A fire-resistant
polycarbonate is the preferred chimney material, such as the material sold as V-O
flame rated polycarbonate, available under the name "Makrolon® 6455" from Bayer
Corporation. The base 112 supports a candle cup 116 positioned centrally within
the chimney 114. The features of the candle cup 116 are best shown in Figs. 19 and
The candle cup 116 is an open-topped, generally cylindrical cup that
contains a wax candle 118. The candle cup 116 has cup walls 120 and a cup floor
122. Preferably the candle 118 has a wick 121 the bottom of which is held by a wick
clip 123. Preferably the wick clip 123 is secured from slipping sidewardly on the
cup floor 122. This can be accomplished in a variety of ways. For example, the wick
clip 123 can simply be glued to the cup floor 122. Alternatively, a clip cup 125
can be formed as a central depression in the cup floor 122 having a diameter sized
to receive the wick clip 123 but to restrain its sideways movement thereafter.
A centrally positioned, downwardly opening socket 124 extends downwardly
from the underside of the cup floor 122. A cup support member 126 also extends downwardly
from the cup floor 122 at least as far as the socket 124 extends and at locations
remote from the socket. The cup support member 126 serves to facilitate manufacture
and filling of the candle cup 116 by allowing the candle cup to sit upright on a
conveyer belt or other surface without interference from the socket 124. The preferred
cup support member 126 extends around the entire margin of the cup floor 122, as
is best seen in Fig. 19. However, it will be appreciated by those skilled in the
art that the cup support member need only be sufficiently remote from the socket
and extend circumferentially sufficiently in one or more locations to provide a
stable support such that the candle cup can sit on a flat surface without tipping.
The candle cup 116 is made of a material sufficiently heat resistant as to be able
to hold a burning candle therewithin without distorting or igniting. Once again,
V-0 flame rated polycarbonate is a preferred material.
As can be best seen in Figs. 16-18, the base 112 has a base floor
128 that has a central ventilation opening 129 that is greater in diameter than
the candle cup 116. Support elements 130 (seen in Fig. 16) extend downwardly from
the underside of the base floor 128 and are attached to and support a wax catcher
132. The wax catcher 132 is a round, horizontally extending tray with low sides,
the wax catcher having a diameter greater than that of the candle cup 116 so that
any wax overflowing from the candle cup 116 lands on and is retained within the
wax catcher. An attachment post 134 (seen in Figs. 17 and 18) extends upwardly from
the wax catcher and is sized to be received within the socket 124 of the candle
cup 116 in firmly gripping relation. By this arrangement, the candle cup 116 is
held within the central ventilation opening 129 with a circumferentially extending
open space surrounding the candle cup walls 120.
The base 112 has ventilation holes 136 that communicate between the
ambient air and the space beneath the base floor 128. When the candle 118 is lit
and the chimney 114 is in place on the base 112, a convective air flow is generated
that pulls air in through the ventilation holes 136, upward under the candle cup
116 and through the open space of the ventilation opening 129 surrounding the candle
cup walls 120, and on up the chimney. As a consequence, the candle 118 is ventilated
from below the level of the candle cup, and consequently the candle cup floor 122
and walls 120 are cooled by the air flow. Furthermore, a sheath of cooler air appears
to form, flowing upwardly within the chimney 114, surrounding the upward, centrally
located flow of hot gases generated by the lit candle 118 and, in fact, tending
to cause the hot gases to form a focused central area within the overall air flow
that is hotter than the more stirred mix of gases and air experienced in a device
otherwise similar but with air vents only at the periphery of the base floor 128.
This pattern of air flow maintains both the candle cup 116 and the walls of the
chimney 114 at a cooler temperature, while focusing a higher heat at the center
of the area contained within the upper part of the chimney. This cooling effect
helps to preserve the candle cup 116 and chimney 114 and make the chimney cooler
to the touch while simultaneously establishing a hot area for driving off volatile
material loaded on a substrate held in that area.
A ceiling 138 is positioned within the chimney 114 at its upper end.
The ceiling 138 has ceiling vents 140 and an insert slot 142 that communicate between
the interior of the chimney 114 and the outside air above the chimney. Hot gases
flowing upwardly from the burning candle 118 can escape the chimney 114 through
the ceiling vents 140. The insert slot 142 is sized to receive a volatile carrier,
such as the mat 144 shown in Figure 16 and following. The preferred mat 144 is flat,
having a linearly extended volatile bearing section 146 with sidewardly extending
ears 148. The volatile bearing section 146 of the mat 144 is made small enough to
be inserted from above into the insert slot 142, while the ears 148 are made too
wide to slip through the insert slot. By this arrangement, the volatile bearing
section 146 can be suspended within the chimney 114, with the mat 144 hanging by
the ears 148, the insert slot 142 and upper surfaces of the ceiling 138 serving
as a carrier holder, holding the volatile carrier--the mat 144--in a portion of
the heating chamber that can be translucent, thus being a location that is visually
A baffle strip 150, made of a heat-resistive material such as metal,
is fastened to the under side of the ceiling 138, the baffle strip extending down
one side of the volatile bearing section 146 of a mat 144 held beneath the ceiling,
then sideways under the entire width of the volatile bearing section, and finally
upwardly along the other side of the volatile bearing section. The baffle strip
150 serves to mix the flow of hot gases rising above the candle 118 and to protect
the downwardly facing edge of the volatile bearing section 146 from the direct impact
of the hottest gases rising from the candle.
The interior of the chimney 114 provides a heating chamber whose walls
are defined by the sidewalls of the chimney. This heating chamber is vented to the
outside air via the ceiling vents 140. The candle cup 116 provides a fuel burner
with the candle 118 being its fuel source. The interior of the chimney 114 defines
an air-flow path that guides the hot gases from the fuel burner past the mat 144,
which is the volatile carrier of the device, to heat the mat by directly exposing
it to the hot gases prior to their escape from the heating chamber into the surrounding
air. The baffle strip 150 provides a baffle similar to the baffles described above
in alternative embodiments of the heated volatile dispenser of the invention.
Preferably, the embodiment of the heated volatile dispenser shown
generally at 110 is adapted to cause its candle 118 to self-extinguish if the dispenser
tips over. The attachment post 134 is sized to be firmly gripped by the socket 124
when the candle cup 116 is installed in the base 112 to the extent necessary to
retain the candle cup in place should the dispenser 110 tip over on its side, as
is shown in Fig. 21. If the candle 118 is burning when the dispenser 110 tips over,
any molten candle wax immediately drains from the now sidewardly opening candle
cup 116. The flame 152 at the wick 121 continues to melt any remaining wax, which
also drains from the candle cup 116, until the level of the wax has been so reduced
as to no longer feed the wick. At that point, the flame 152 extinguishes. Although
Fig. 20 illustrates a situation in which the candle cup 116 is sufficiently tipped
as to be presented downwardly from the horizontal, the flame 152 will self-extinguish
when tipped at any angle sufficient to allow molten wax to drain down to the level
that the wick 121 becomes starved for fuel.
Fig. 22 is side elevational view (and Fig. 23 is a cross sectional
view) of an alternative embodiment of the heated volatile dispenser of the invention,
shown generally at 154. Volatile dispenser 154 is a modified form of the heated
volatile dispenser 110 of Fig. 16. All parts of volatile dispenser 154 that directly
correspond to parts of the volatile dispenser 110 are identified by the same reference
numbers with the addition of the letter "a", without further discussion.
The volatile dispenser 154 differs from the volatile dispenser 110
in that dispenser 154 is designed to be hung from a hook or other overhead support
(not shown). A hanger 156 capable of hanging from such a hook is attached to the
upper part of the chimney 114a, preferably in freely turning relation to the chimney
so that the weight of the dispenser 154 causes it to hang directly downwardly from
the hook or other overhead support. This arrangement allows dispenser 154 to function
generally in the same way as does dispenser 110 when dispenser 110 is resting on
a horizontal surface.
The other differences between dispensers 154 and 110 all reside in
the base 112a. The base 112a has a floor 158 that is downwardly curved at its center
so as to discourage the use of dispenser 154 except by being hung.
The base 112a has an attachment post 134a that is sized to be received
within the socket 124 of a candle cup 116. The attachment post 134a is located at
the top of a central pedestal 160 that rises from the floor 158. When a candle cup
116 is mounted on the attachment post 134a, it is importantly advantageous for the
cup walls 120 and cup floor 122 to be freely veritilated. Therefore, preferably
the diameter of the central pedestal 160 is less than that of such a candle cup
116 for a distance beneath the bottom of the candle cup sufficient to allow for
such ventilation. Preferably, the top of the pedestal 160 is an upwardly pointing
cone or comparable, upwardly diminishing shape that terminates in the attachment
post 134a, as is shown in Fig. 23. Also preferably, the central pedestal 160 is
hollow and opens downwardly from the base 112a, allowing the dispenser 154 to be
alternatively mounted on a stake or post (not shown) inserted into the central pedestal
Base ventilation holes 136a are spaced around the base 112a at a level
beneath that of the cup floor 122 of a candle cup 116 when it is mounted on the
attachment post 134a. The base ventilation holes 126a communicate between the ambient
air and the interior of the base. Thus, as in the dispenser 110, a candle cup 116
mounted on the attachment post 134a is held within a circumferentially extending
open space. As in the dispenser 110, when a candle 118 is lit and the chimney 114a
is in place on the base 112a, a convective air flow is generated that pulls air
in through the ventilation holes 136a, upward under the candle cup 116 and through
the open space surrounding the candle cup walls 120, and on up the chimney. As a
consequence, the candle 118 is ventilated from below the level of the candle cup
116. Consequently the candle cup floor 122 and walls 120 are cooled, and the beneficial
pattern of air flow discussed above with respect to the dispenser 110 is established.
A preferred embodiment of the kit of the invention, as disclosed above,
includes at least one candle as a fuel source and at least one volatile carrier.
The preferred candle is a candle 118, as already described, contained within a candle
cup 116, and is made of paraffin wax with a preferred weight of from 15 to 20 grams
and an especially preferred weight of from 16 to 17 grams. Ideally, the candle is
made by the process of bonding small wax granules by simply forcefully pressing
them in a compression mold. The technique is well known in the candle making art
and produces candles of consistent dimensions and densities. The preferred candle,
whether made by that or any other method, has a diameter of about 37 mm and an overall
height at the candle's center of about 20 mm, the height tapering down to about
15 mm at the circumference of the candle. A candle of this size will burn for about
The preferred volatile carrier for the kit when used with the candle
just described is made of conventional, fibrous mosquito mat material and preferably
of a cellulosic, felted pulp mat material. The preferred mat weighs approximately
1 gram before being treated with ah insect control material, including the standard
5 to 7% moisture absorbed by such materials. Each such mat is treated with approximately
375 mg of d-cis/trans allethrin (or about 22% by weight of the mat) as a volatile
insect control active ingredient. The heat from the preferred candle just described
is sufficient to exhaust the d-cis/trans allethrin from the mat by the time the
candle has been consumed, when the mat is positioned edge-on at approximately 9.5
cm above the candle in a location free of side drafts, such as is found within the
heated volatile dispenser shown in Figs. 16 and following. The term "exhaust" has
the meaning previously defined.
The various parts of the dispenser described above can be manufactured
by conventional means from heat-resistant plastics, metal, glass, and the like.
The volatile carriers disclosed can be made using conventional methods and materials
well known in the art, such as those used for making conventional mosquito mats,
volatile gel carriers, volatile-containing polymers, and the like.
The preceding description is merely of preferred embodiments of the
invention. One skilled in the art will readily apprehend alternative embodiments
that nevertheless fall within the scope and breadth of the invention. Thus, the
claims should be looked to in order to understand the full scope of the invention.
Heated volatile dispensers and volatile carriers, and methods of using
them, are described. They are useful in the practical control of insects and other
pests and in air scenting.