U.S. patent application number 12/206258 was filed with the patent office on 2009-12-03 for portable vaporizer for plant material.
This patent application is currently assigned to VAPOR FOR LIFE. Invention is credited to Michael J. McBride, Glenn L. Williams.
Application Number | 20090293888 12/206258 |
Document ID | / |
Family ID | 41378247 |
Filed Date | 2009-12-03 |
United States Patent
Application |
20090293888 |
Kind Code |
A1 |
Williams; Glenn L. ; et
al. |
December 3, 2009 |
PORTABLE VAPORIZER FOR PLANT MATERIAL
Abstract
A portable vaporizer for plant material has an inhalation tube
having a distal end for insertion into a cigarette lighter
receptacle of a vehicle. An electrical heating element within the
inhalation tube is powered by the vehicle's electrical system when
the inserted into the cigarette lighter receptacle. A plant
material chamber on the proximal end of the inhalation tube has
openings allowing air from the inhalation tube to be drawn through
the inhalation tube, heated by the electrical heating element, and
then drawn through an air-permeable pouch containing plant material
held in the plant material chamber. A housing having a mouthpiece
and baffles surrounds the plant material chamber to reduce the
temperature of the heated air and vaporized plant material. The
user inhales the mixture of heated air and vaporized plant material
through the mouthpiece by drawing air through the inhalation tube,
plant material chamber and housing.
Inventors: |
Williams; Glenn L.;
(Evergreen, CO) ; McBride; Michael J.; (Superior,
CO) |
Correspondence
Address: |
DORR, CARSON & BIRNEY, P.C.;ONE CHERRY CENTER
501 SOUTH CHERRY STREET, SUITE 800
DENVER
CO
80246
US
|
Assignee: |
VAPOR FOR LIFE
Evergreen
CO
|
Family ID: |
41378247 |
Appl. No.: |
12/206258 |
Filed: |
September 8, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12129845 |
May 30, 2008 |
|
|
|
12206258 |
|
|
|
|
Current U.S.
Class: |
131/178 |
Current CPC
Class: |
A24F 40/46 20200101;
A24F 40/20 20200101; A24F 40/42 20200101; A24F 40/485 20200101;
A24F 47/008 20130101 |
Class at
Publication: |
131/178 |
International
Class: |
A24F 13/12 20060101
A24F013/12 |
Claims
1. A portable vaporizer for plant material comprising: a distal end
for insertion into a cigarette lighter receptacle of a vehicle; an
electrical heating element powered by the electrical system of the
vehicle when the distal end of the vaporizer is inserted into a
cigarette lighter receptacle; an air-permeable pouch containing
plant material; a plant material chamber for holding the pouch and
having openings allowing heated air from electrical heating element
to be drawn through the pouch and plant material; and a housing
having a mouthpiece for drawing air through the plant material
chamber and pouch to produce a mixture of heated air and vaporized
plant material.
2. The vaporizer of claim 1 wherein the pouch is comprised of a
plastic mesh.
3. The vaporizer of claim 1 wherein the plant material chamber is
within the housing and further comprises an external opening
extending through the housing to receive the pouch, with a
removable cap covering the opening of the plant material
chamber.
4. The vaporizer of claim 1 wherein the housing further comprises
baffles between the plant material chamber and mouthpiece.
5. A portable vaporizer for plant material comprising: an
inhalation tube having a distal end for insertion into a cigarette
lighter receptacle of a vehicle; an electrical heating element
within the inhalation tube powered by the electrical system of the
vehicle when the inhalation tube is inserted into a cigarette
lighter receptacle, said inhalation tube enabling air to be drawn
through the inhalation tube and heated by the electrical heating
element; an air-permeable pouch containing plant material; a plant
material chamber for holding the pouch and having openings allowing
heated air from the inhalation tube to be drawn through the plant
material in the pouch; and a housing having a mouthpiece for
drawing air through the inhalation tube, plant material chamber and
pouch to produce a mixture of heated air and vaporized plant
material.
6. The vaporizer of claim 5 wherein the housing further comprises
baffles between the plant material chamber and mouthpiece.
7. The vaporizer of claim 5 further comprising a heat transfer
element in the inhalation tube transferring heat from the
electrical heating element to air in the inhalation tube.
8. The vaporizer of claim 5 wherein the electrical heating element
is within the distal end of the inhalation tube to make electrical
connection with electrical contacts in a cigarette lighter
receptacle when the inhalation tube is inserted into a cigarette
lighter receptacle.
9. The vaporizer of claim 5 further comprising an outer housing
surrounding the distal end of the inhalation tube, and a spring
between the outer housing and inhalation tube to partially eject
the vaporizer from a cigarette lighter receptacle when the
electrical heating element reaches a predetermined temperature.
10. The vaporizer of claim 5 wherein the plant material chamber is
within the housing and attached to the proximal end of the
inhalation tube.
11. The vaporizer of claim 10 wherein the plant material chamber
has an external opening extending through the housing to receive
plant material, and further comprising a removable cap covering the
opening of the plant material chamber.
12. A portable vaporizer for plant material comprising: an
inhalation tube having a proximal end and a distal end for
insertion into a cigarette lighter receptacle of a vehicle; an
electrical heating element within the distal end of the inhalation
tube powered by the electrical system of the vehicle when the
inhalation tube is inserted into a cigarette lighter receptacle; a
housing having an interior and a mouthpiece; an air-permeable pouch
containing plant material; and a plant material chamber for holding
the pouch on the proximal end of the inhalation tube and enclosed
within the housing, said plant material chamber having at least one
opening into the interior of the housing; wherein negative pressure
at the mouthpiece of the housing draws air through the inhalation
tube where the air is heated by the heated element and then drawn
through the plant material chamber and pouch to produce a mixture
of heated air and vaporized plant material.
13. The vaporizer of claim 12 further comprising baffles between
the plant material chamber and the mouthpiece.
14. The vaporizer of claim 12 further comprising a heat transfer
element in the inhalation tube transferring heat from the
electrical heating element to air in the inhalation tube.
15. The vaporizer of claim 12 wherein the electrical heating
element is within the distal end of the inhalation tube to make
electrical connection with electrical contacts in a cigarette
lighter receptacle when the inhalation tube is inserted into a
cigarette lighter receptacle.
16. The vaporizer of claim 12 further comprising an outer housing
surrounding the distal end of the inhalation tube, and a spring
between the outer housing and inhalation tube to partially eject
the vaporizer from a cigarette lighter receptacle when the
electrical heating element reaches a predetermined temperature.
17. The vaporizer of claim 12 wherein the plant material chamber
has an external opening extending through the housing to receive
plant material, and further comprising a removable cap covering the
opening of the plant material chamber.
Description
RELATED APPLICATION
[0001] The present application is a continuation-in-part of the
Applicants' co-pending U.S. patent application Ser. No. 12/129,845,
entitled "Portable Vaporizer For Plant Material," filed on May 30,
2008.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to the field of
vaporizers for releasing essential active constituents, such as
nicotine, by heating plant materials. More specifically, the
present invention discloses a portable vaporizer for plant
materials.
[0004] 2. Statement of the Problem
[0005] Inhalation devices for smoking tobacco or vaporizing various
medicaments (e.g., nicotine) from plant materials are known in the
art. These devices typically include an electrical heating element
for igniting the tobacco or medicament. The resulting smoke and/or
vapor is then inhaled by the user.
[0006] For example, U.S. Pat. No. 7,293,565 (Griffin et al.)
discloses an electrically-heated cigarette smoking system with a
stand containing a rechargeable power supply. As shown in FIGS.
13-16 of Griffin et al., the stand can also include recharging
electronics powered by an adapter that plugs into the cigarette
lighter of a vehicle.
[0007] However, there remains a need for an easy to use, hand-held
device that allows for the release of the essential active
constituents of a plant substance through vaporization, using
sufficient heat and air to release them without burning the
substance and without creating the toxic byproducts of combustion.
This not only reduces the health risk to the user but also to
neighboring non-smokers by alleviating second-hand smoke. In
addition, there remains a need for a portable vaporizer that can be
plugged directly into a conventional vehicle cigarette lighter.
[0008] Solution to the Problem. The present invention allows for
the inhalation of the active constituents of a plant material by
vaporization, rather than combustion. It includes a housing
configured and sized to fit in the user's hand during use. In
addition, it can be plugged into a conventional automobile
cigarette lighter to create a heated air stream that is drawn
through the plant material to produce a substance vapor that can be
inhaled by an individual. The present device is unique in that it
can be plugged into a conventional vehicle cigarette lighter and is
completely independent of any power source once the electrical
heating element has reached temperature.
SUMMARY OF THE INVENTION
[0009] This invention provides a portable vaporizer for plant
material having an inhalation tube with a distal end for insertion
into a cigarette lighter receptacle of a vehicle. An electrical
heating element within the inhalation tube is powered by the
vehicle's electrical system when inserted into a cigarette lighter
receptacle. A plant material chamber on the proximal end of the
inhalation tube has openings allowing air from the inhalation tube
to be drawn through the inhalation tube, heated by the electrical
heating element, and then drawn through an air-permeable pouch
containing plant material held in the plant material chamber. A
housing having a mouthpiece and baffles surrounds the plant
material chamber to reduce the temperature of the heated air and
vaporized plant material. The user inhales the mixture of heated
air and vaporized plant material through the mouthpiece by drawing
air through the inhalation tube, plant material chamber and
housing.
[0010] These and other advantages, features, and objects of the
present invention will be more readily understood in view of the
following detailed description and the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The present invention can be more readily understood in
conjunction with the accompanying drawings, in which:
[0012] FIG. 1 is a front perspective view of a portable vaporizer 5
embodying the present invention.
[0013] FIG. 2 is a rear perspective view of the vaporizer 5
corresponding to FIG. 1.
[0014] FIG. 3 is a perspective view of a vaporizer 5 with the lid
32 removed and plant material 35 being loaded into the plant
material chamber within the housing.
[0015] FIG. 3a is a perspective view of a vaporizer 5 with the lid
32 removed and a pouch 37 containing plant material 35 being loaded
into the plant material chamber within the housing.
[0016] FIG. 4 is a perspective view of the vaporizer 5 inserted
into the cigarette lighter socket 50 in the dashboard of a
vehicle.
[0017] FIG. 5 is a side view of a user inhaling through the
vaporizer 5.
[0018] FIG. 6 is a horizontal cross-sectional view of the vaporizer
5.
[0019] FIG. 7 is a vertical cross-sectional view of the vaporizer
5.
[0020] FIG. 8 is an exploded cross-sectional view of the inhalation
tube and plant material chamber assembly.
[0021] FIG. 9 is a cross-sectional view of the distal end of the
vaporizer 5 initially inserted in a cigarette lighter socket
50.
[0022] FIG. 10 is a cross-sectional view corresponding to FIG. 9
after the vaporizer 5 has been fully inserted in the cigarette
lighter socket 50 to power the electrical heating element 20.
[0023] FIG. 11 is a cross-sectional view corresponding to FIGS. 9
and 10 after the electrical heating element 20 has been heated and
the bimetallic leaf springs 54 have released the vaporizer 5 to pop
out.
[0024] FIG. 12 is a cross-sectional view corresponding to FIGS.
9-11 showing subsequent removal of the vaporizer 5 from the
cigarette lighter socket 50.
[0025] FIG. 13 is a cross-sectional view of an embodiment of a
vaporizer with a heat transfer element 26 to carry heat from the
electrical heating element 20 to the air stream in the inhalation
tube 10.
[0026] FIG. 14 is a cross-sectional view orthogonal to FIG. 13.
DETAILED DESCRIPTION OF THE INVENTION
[0027] FIGS. 1 and 2 are front and rear perspective views of an
embodiment of the present invention. This embodiment is shown in
further detail in the cross-sectional views of the vaporizer 5
depicted in FIGS. 6 and 7. The major components of the vaporizer 5
include an inhalation tube 10, an electrical heating element 20, a
housing 40, and a plant material chamber 30.
[0028] FIG. 8 is an exploded cross-sectional view of the inhalation
tube 10 and plant material chamber 30 assembly. The distal end of
the inhalation tube 10 is designed for insertion into the socket of
a conventional cigarette lighter socket 50 of a vehicle. An
electrical heating element 20 is located at the distal end of the
inhalation tube 10. This heating element 20 is initially powered by
vehicle's electrical system, and then used to heat air drawn
through the inhalation tube 10 after the vaporizer 5 has been
withdrawn from the cigarette lighter socket 50. For example, the
electrical heating element 20 can be a modified cigarette heating
coil. The temperature of a lighter heating element is initially
about 800.degree.-1200.degree. C., cooling to a temperature greater
than 450.degree. C. within about 10 seconds. The dimensions and
thermodynamic properties of the inhalation tube 10 can be selected
to result in a selected air temperature entering the plant material
chamber 30 to cause vaporization of the desired medicaments from
the plant material 35. For example, a temperature of about
125.degree.-150.degree. C. is suitable to vaporize the active
constituents of tobacco.
[0029] The inhalation tube 10 provides a pathway for a heated air
stream from the electrical heating element 20 at the distal end of
the inhalation tube 10 to the plant material chamber 30 on the
proximal end of the inhalation tube 10. Air flows through the
inhalation tube 10 into the plant material chamber 30 and is
generally insulated by the inhalation tube 10 to maintain the
temperature of the air flow entering the plant material chamber 30.
The inhalation tube 10 is also the stress point between the housing
40 and the heating element 20 and will absorb the forces produced
by engaging the vaporizer with the cigarette lighter receptacle 50.
For example, the inhalation tube 10 can be constructed of a
heat-resistant material, such as medically-safe ceramic. The
embodiment of the inhalation tube 10 shown in the drawings is a
straight tube. It should be understood that the inhalation 10 could
have any desired shape or cross-section.
[0030] The assembly at the distal end of the inhalation tube 10
also includes a number of components to enable the vaporizer 5 to
interface with a conventional cigarette lighter socket 50, as
illustrated for example in FIGS. 4 and 8-12. Returning to FIG. 8,
the distal end of the inhalation tube 10 can be secured to a
conventional cigarette lighter barrel 24 housing the electrical
heating element 20, to minimize manufacturing costs. The barrel 24
is typically constructed as a single extruded tube which will allow
air to flow freely through the heating element 20 through the
barrel 24 and into the inhalation tube 10, as will be described
below. For example, the distal end of the inhalation tube 10 can be
coupled to the barrel 24 by a tubular inhalation guard 13, which
inserts into the open end of the barrel 24 and is secured by lugs
and/or a friction fit. The inhalation guard 13 also fits over the
distal end of the inhalation tube 10 and is secured by lugs 14 that
are bent inward to engage ribs or threads on the exterior surface
of the inhalation tube 10, as shown in FIGS. 9-12.
[0031] A cylindrical outer housing 15 surrounds the barrel 24 and
inhalation 13. The diameter of the outer housing 15 is designed to
allow the distal end of the inhalation tube 10, inhalation guard 13
and barrel 24 to freely slide as an assembly within the outer
housing 15 along its central axis. A spring 18 surrounds the
exterior of the barrel 24 within the outer housing 15. This spring
18 is compressed between a flange at the proximal (upper) end of
the inhalation guard 13 and an annular shoulder 16 in the interior
surface of the outer housing 15 as the inhalation tube assembly 10,
13 and 24 advances. The corresponding annular shoulder 16 on the
exterior surface of the outer housing 15 also acts as a stop to
limit the extent to which the vaporizer 5 can be inserted into a
conventional cigarette lighter socket 50.
[0032] The distal (lower) portion of the barrel 24 forms an annular
skirt 25 that extends radially outward and surrounds the electrical
heating element 20, as shown in FIGS. 8-12. When the vaporizer 5 is
fully inserted into a lighter socket 50, bimetallic leaf springs 54
in the socket 50 grip this skirt 25 to hold the vaporizer 5 in
place, as shown in FIG. 10, while the electrical heating element
heats. The spring 18 is compressed during this period and exerts a
biasing force that is held in check by the bimetallic leaf springs
54. However, when the electrical heating coil 20 has heated the
adjacent bimetallic leaf springs 54 to a predetermined temperature,
the bimetallic leaf springs 54 deform outward sufficiently to
release the skirt 25 of the barrel 24. The spring 18 then causes
the vaporizer to partially eject from the cigarette lighter socket
50. In other words, the spring causes the lighter to "pop" out a
short distance, as illustrated in FIG. 11. This breaks the
electrical contact between the rivet 22 and the electrical contact
52 in the base of the socket 50. The vaporizer 5 can then be
withdrawn from the cigarette lighter socket 50, as shown in FIG.
12.
[0033] It should be noted that other types of bimetallic springs or
heat-sensitive mechanisms could be substituted for the leaf springs
54 For example, a bimetallic disk behind the electrical heating
element 20 could be employed to pop-out the vaporizer 5.
[0034] A convection plate 12 is mounted above the neck of the
barrel 24 to serve as the point of attachment for the heating coil
20 by a metal rivet 22. The convection plate 12 also has a pattern
of holes that will allow air to pass from the electrical heating
element 20 into the barrel 24 and through the inhalation tube 10.
The pattern and size of holes help to determine the amount of air
flow and the temperature of the air stream through the inhalation
tube 10.
[0035] The electrical heating element 20 can be constructed as a
flat coil of nickel-chrome wire. For example, the electrical
heating element 20 can be made of a corrosion-resistant wire made
of 80% nickel and 20% chromium with a melting point of about
1400.degree. C. Ni-chrome wire can be wound into a thin coil to a
predetermined electrical resistance and when current from the
vehicle's electrical system (typically about 15-20 amps) is passed
through the heating element 20, it produces heat. The center of the
electrical heating element 20 is attached to the metal rivet 22 and
the periphery of the heating element 20 is attached to the skirt 25
at the distal end of the barrel. The rivet 22 and barrel 24 serve
as the electrical contacts to establish a complete circuit between
the vehicle's electrical system (i.e., battery) and the electrical
heating element 20. In particular, an electrical contact 52 in the
base of the socket 50 makes contact with the rivet 22 when the
distal end of the vaporizer 5 is fully inserted into a cigarette
lighter socket 50, as shown in FIG. 10. The other electrical
contact for powering the heating coil 20 made through the metal
barrel 24, which is in contact with the metal wall of the socket 50
that is grounded to the vehicle.
[0036] An O-ring seal 19 between the convection plate 12 and
inhalation tube 10 can be used to form an air-tight seal between
the electrical heating coil 20 and the inhalation tube 10. When the
inhalation tube 10 is secured in the inhalation guard it is pressed
onto the inhalation seal 19 which forms an air seal forcing the air
stream to flow through the electrical heating coil 20 and into the
inhalation tube 10 without ambient-temperature air leaking into the
air stream. The inhalation seal 19 can be made from a
heat-resistant, medicinally-safe, yet pliable material, such as
silicone.
[0037] The plant material chamber 30 is attached at the proximal
end of the inhalation tube 10 and is typically enclosed within the
housing 40. In particular, the proximal end of the inhalation tube
10 is fitted into one side or the bottom of the plant material
chamber 30 and sealed with a gasket. This gasket forms a seal
between the plant material chamber 30 and the inhalation tube 10
and completes the air tight seal from the heating coil 20 to the
plant material chamber 30. The plant material chamber 30 can
perforated by elongated vents or openings 34 about its outer
surface. These vents 34 provide non-restricted air flow from the
inhalation tube 10 through of the plant material chamber 30 into
the interior of the housing 40. The plant material chamber 30 can
be generally cup-shaped with an opening extending through the wall
of the housing 40 to accept a removable, air-permeable material
holder 31 containing a quantity of plant material 35 for
vaporization, as shown in FIG. 3. During use of the vaporizer 5,
the open end of the plant material chamber 30 is sealed by a cover
or lid 32 to maintain air flow through the inhalation tube 10 and
electrical heating element 20. The heated air stream flows from the
heating coil 20 through the inhalation tube 10 and into the plant
material chamber 30 where vaporization of the plant material 35
occurs. This vapor stream is drawn through the openings 34 in the
plant material chamber 30 into the interior of housing 40, and
exits the housing 40 through the mouthpiece 44 at the proximal end
of the housing 40 as the user inhales. The inhalation tube 10,
plant material chamber 30, seals, lid 32, and baffles 42 can be
made of heat-resistant, medicinally-safe materials, such as
ceramic, to provide thermal insulation. Charcoal can be placed into
the inhalation tube 10 to help alleviate any unwanted taste from
the heating element 20. Optionally, the plant material chamber 30
can also include a filter to help contain the plant material 15 and
filter the vapor stream
[0038] The housing 40 can have an egg-shaped or ovoid
cross-section, for example. The interior of the housing 40 can
include a number of baffles 42 to create a more circuitous route
for air flow from the plant material chamber 30 to the mouthpiece
44 and provide additional cooling and mixing of the vapor stream.
The distal end of the housing 40 can be flared radially outward
adjacent to the proximal end of the outer lighter housing 15 to
provide a tactile device to help prevent the user from sliding
fingers over the heating assembly. The housing 40 can either be
made of heat-resistant, medicinally-safe materials, such as
ceramic, to provide thermal insulation, or it can made of a
suitable polymer capable of withstanding the temperatures
involved.
[0039] To use the vaporizer 5, the user initially places a quantity
of plant material 35 into the plant material chamber 30 of the
vaporizer 5. For example, this can be done by removing the cap 32
covering the external opening to the plant material chamber 30 and
then inserting an appropriate amount of the plant material 35 into
the material holder 31, which is placed into the plant material
chamber 30 as depicted in FIG. 3. The lid 32 is then replaced to
close the external opening of the plant material chamber 30 and
retain the material holder 31 and plant material 35 within the
plant material chamber 30, as shown for example in FIG. 7
[0040] FIG. 3a shows another embodiment of the present invention in
which the plant material 35 is held within a pouch or pod 37 made
of a suitable high-temperature material, such as air-permeable
mesh. The pouch 37 is placed within the plant material chamber 30
of the vaporizer 5, and the lid 32 is then replaced to close the
plant material chamber 30. The pod 37 can be a casing formed around
a quantity of plant material that allows air to pass freely through
the pouch material as well as the plant material. The plant
material should be loosely packed so that air can freely circulate
through it. The pod 37 should be capable of withstanding heated air
up to about 365.degree. F., but will generally be used at about
250.degree. F. in addition, the pouch material should be
medicinally safe throughout its range of operating temperatures.
For example, the pod 37 can be made of plastic mesh, such as nylon
screening cloth, which is commercially available as a mesh. This
material can be sterilized and is safe up to 437.degree. F. It is
also certified by the FDA. The pod 37 can be manufactured using
thermal vacuum molding to form the body of the pod 37, followed by
ultrasonic welding to seal the plant material within the pod
37.
[0041] Next, the user inserts the distal end of the inhalation tube
into the cigarette lighter receptacle 50 of a vehicle to connect
the electrical heating element 20 to the electrical system of the
vehicle. This is shown in the perspective view provided in FIG. 4.
FIG. 9 is a cross-sectional view of the distal end of the vaporizer
5 initially inserted in a cigarette lighter socket 50. FIG. 10
shows the vaporizer fully inserted to heat the electrical heating
element 20. FIG. 11 is a cross-sectional view after the electrical
heating element 20 has been heated and the bimetallic leaf springs
54 have released the vaporizer 5 to pop out. The user then
withdraws the vaporizer 5 from the cigarette light receptacle 50 as
shown in FIG. 12.
[0042] The user inhales through the mouthpiece 44 as shown in FIG.
5, thereby creating negative pressure to draw air through the
inhalation tube 10 where it is heated by the heated element 20 and
then drawn through the plant material chamber 30 to produce a
mixture of heated air and vaporized plant material. In the
embodiment shown in FIG. 3a, the heated air is drawn through both
the plant material chamber 30 and the air-permeable pouch 37
contained within to produce a mixture of heated air and vaporized
plant material. This mixture of heated air and vaporized plant
material is drawn out of the plant chamber 30 through its openings
34 into the interior of the housing 40. The vapor stream is
directed by the baffles 42 within the housing 40 and exits via the
mouthpiece 44.
[0043] FIGS. 13-14 show two orthogonal cross-sectional views of an
embodiment of the present invention that includes a heat transfer
element 26 to transfer heat from the heating coil 20 to the
airstream in the inhalation tube 10. The heat transfer element 26
is in thermal contact with the heating coil 20 and conducts heat
axially within the inhalation tube. This configuration can also
include a number of air intake openings 11 extending through the
wall of the inhalation tube 10 at a distance above the heating coil
20. Air entering through these openings 11 will be heated by the
heat transfer element 26 before entering the plant material chamber
30. If desired, air flow through the heating coil 20 can be blocked
by a ceramic spacer 27 to provide a more moderate and uniform air
temperature entering the plant material chamber 30. This spacer 27
replaces the perforated convection plate 12 shown in the previous
embodiment. Blocking air flow through the heating coil 20 might
also help to reduce any unpleasant taste or smell associated with
the heating coil 20.
[0044] The heat transfer element 26 can have any desired
configuration and be made of any material having suitable thermal
conductivity. For example, the heat transfer element 26 can be made
of thermal pyrolytic graphite (TPG) available from Momentive
Performance Materials, Inc. of Strongsville, Ohio. This material is
made by chemical vapor deposition of cracked methane, followed by a
combination of pressure and thermal treatment at very high
temperatures, to produce a material with an in-plane thermal
conductivity of more than 1500 W/m deg. K. In contrast, copper has
a thermal conductivity of about 400 W/m deg. K. TPG is somewhat
fragile and is usually supplied embedded in an aluminum plate.
[0045] The above disclosure sets forth a number of embodiments of
the present invention described in detail with respect to the
accompanying drawings. Those skilled in this art will appreciate
that various changes, modifications, other structural arrangements,
and other embodiments could be practiced under the teachings of the
present invention without departing from the scope of this
invention as set forth in the following claims.
* * * * *