U.S. patent application number 15/369961 was filed with the patent office on 2018-06-07 for heater element for a vaporization device.
The applicant listed for this patent is Funai Electric Co., Ltd.. Invention is credited to Byron V. BELL.
Application Number | 20180153215 15/369961 |
Document ID | / |
Family ID | 60582491 |
Filed Date | 2018-06-07 |
United States Patent
Application |
20180153215 |
Kind Code |
A1 |
BELL; Byron V. |
June 7, 2018 |
HEATER ELEMENT FOR A VAPORIZATION DEVICE
Abstract
A heating element for a vaporizing device, a vaporizing device
containing the heating element, and a method for vaporizing fluid
ejected by an ejection head. The heating element includes a
conductive material deposited onto an insulative substrate, a
protective layer deposited onto the conductive layer, and a porous
layer having a porosity of at least about 50% deposited onto the
protective layer. The heating element has an effective surface area
(ESA) for fluid vaporization that is greater than a planar surface
area defined by dimensions of the heating element so that a fluid
contact surface of the heating element is greater than the planar
surface area of the heating element.
Inventors: |
BELL; Byron V.; (Lexington,
KY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Funai Electric Co., Ltd. |
Osaka |
|
JP |
|
|
Family ID: |
60582491 |
Appl. No.: |
15/369961 |
Filed: |
December 6, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61M 15/0021 20140204;
H05B 3/44 20130101; A61M 15/06 20130101; A61M 11/042 20140204; A61M
2205/8206 20130101; A61M 2205/8237 20130101; A24F 47/008 20130101;
A61M 2205/3653 20130101 |
International
Class: |
A24F 47/00 20060101
A24F047/00; H05B 3/44 20060101 H05B003/44; A61M 11/04 20060101
A61M011/04; A61M 15/00 20060101 A61M015/00 |
Claims
1. A heating element for a vaporization device comprising a
conductive material deposited onto an insulative substrate, a
protective layer deposited onto the conductive layer, and a porous
layer having a porosity of at least about 50% deposited onto the
protective layer wherein the heating element has an effective
surface area (ESA) for fluid vaporization that is greater than a
planar surface area defined by dimensions of the heating element so
that a fluid contact surface of the heating element is greater than
the planar surface area of the heating element.
2. The heating element of claim 1, wherein the heating element has
a rectangular shape and has an effective surface are for fluid
vaporization defined by the equation ESA>L.times.W, wherein L is
a length of the heating element and W is a width of the heating
element.
3. The heating element of claim 1, wherein the porous layer has a
grit blasted surface texture providing the effective surface area
(ESA) thereof.
4. The heating element of claim 1, wherein the porous layer has a
thickness ranging from about 0.5 millimeters (mm) to about 3
mm.
5. The heating element of claim 1, wherein the insulative
substrate, conductive layer and protective layer have a combined
thickness ranging from about 4 millimeters (mm) to about 1
centimeter (cm).
6. The heating element of claim 1, wherein the porous layer has a
porosity ranging from about 50% to about 95%.
7. The heating element of claim 1, wherein the conductive layer is
a screen printed conductive layer deposited onto a ceramic
substrate.
8. The heating element of claim 1, wherein the porous layer
comprises a laser etched ceramic layer.
9. The heating element of claim 1, wherein the porous layer
comprises a coarse grit deposited ceramic layer that is
sintered.
10. A vaporization device comprising a housing body, a mouthpiece
attached to the housing body, and a heating element disposed
adjacent to the mouthpiece for vaporizing fluid ejected from an
ejection head, wherein the heating element comprises a conductive
material deposited onto an insulative substrate, a protective layer
deposited onto the conductive layer, and a porous layer having a
porosity of at least about 50% deposited onto the protective
layer.
11. The vaporization device of claim 10, wherein the heating
element has a rectangular shape and has an effective surface area
(ESA) for fluid vaporization defined by the equation
ESA>L.times.W, wherein L is a length of the heating element and
W is a width of the heating element.
12. The vaporization device of claim 11, wherein the porous layer
has a grit blasted surface texture providing the effective surface
area (ESA) thereof.
13. The vaporization device of claim 10, wherein the porous layer
has a thickness ranging from about 0.5 millimeters (mm) to about 3
mm.
14. The vaporization device of claim 10, wherein the insulative
substrate, conductive layer and protective layer have a combined
thickness ranging from about 4 millimeters (mm) to about 1
centimeter (cm).
15. The vaporization device of claim 10, wherein the porous layer
has a porosity ranging from about 50% to about 95%.
16. A method for vaporizing a fluid ejected by an ejection head so
that substantially all of the fluid ejected by the ejection head is
vaporized, comprising providing a vaporization device having an
ejection head and a vaporizing heater element adjacent to the
ejection head; ejecting fluid onto the heater element; activating
the heating element during fluid ejection; and vaporizing
substantially all of the fluid using the heating element, wherein
the heating element comprises a conductive material deposited on an
insulative substrate, a protective layer deposited on the
conductive layer, and a porous layer having a porosity of at least
about 50% deposited onto the protective layer.
17. The method of claim 16, further comprising absorbing the fluid
by the porous layer of the heating element, wherein the porosity of
the heating element is defined by the equation ESA>L.times.W,
wherein ESA is an effective surface area of the heating element, L
is a length of the heating element and W is a width of the heating
element having a rectangular shape and that is exposed to a
vaporizing fluid.
18. The method of claim 16, wherein the porous layer is deposited
as a coarse glass frit that is sintered onto the protective layer
of the heating element.
19. The method of claim 16, wherein the porous layer is formed by
grit blasting the protective layer or a ceramic layer deposited
onto the protective layer of the heating element.
20. The method of claim 16, wherein the porous layer is formed by
laser etching the protective layer or a ceramic layer deposited
onto the protective layer of the heating element.
Description
TECHNICAL FIELD
[0001] One of the applications of a fluidic ejection device is to
jet a solution onto to another device where a secondary function
may be performed. A common secondary function is to vaporize a
solution using a heater such that the contents of the solution can
be vaporized so as to deliver the solution as a gaseous substance.
Applications of such technology include, but are not limited to,
metering and vaporizing device for electronic cigarettes, vapor
therapy, gaseous pharmaceutical delivery, vapor phase reactions for
micro-labs, and the like. A problem associated with such devices is
efficient vaporization of the fluid. This document discloses
improved heating elements and methods for improving the
vaporization efficiency of heating elements for vaporization
devices.
BACKGROUND AND SUMMARY
[0002] When jetting a fluid onto a heated surface it is highly
desirable for 100% of the fluid to vaporize so that liquid is not
discharged from the vaporizing device. The problem lies in that the
vaporizing heater must be small enough to heat up extremely
quickly, but yet has enough surface area to catch all fluid and
fluid droplets that are being ejected onto the heating element. A
typical metal foil heating element has a smooth surface with
minimal liquid/heater interface which is due to a low surface
roughness of the heating element surface. Accordingly, some of the
fluid droplets impinging on the surface of the heating element will
be scattered or fluid droplets will be ejected from the heating
element if a significant layer of fluid already exists on the
surface of the heating element when new droplets arrive. Thus,
instead of only vapor being discharged from the vaporization
device, liquid droplets may be entrained in the vapor and
discharged from the vaporization device. In some applications, the
discharge of liquid is not only undesirable, but may be detrimental
to the user. Also, unvaporized fluid may build up inside the
vaporization device and thus degrade the operation of the
device.
[0003] In order to avoid the discharge of liquid droplets from a
vaporization device, the stream of fluid ejected onto the surface
of the heating element must be efficiently captured by the heating
element, spread out over the surface of the heating element, and
completely vaporized at approximately the same rate as the fluid
arrives on the surface of the heating element in order to avoid
liquid accumulation on the surface of the heating element.
[0004] In view of the foregoing, embodiments of the disclosure
provide a heating element for a vaporizing device, a vaporizing
device containing the heating element, and a method for vaporizing
fluid ejected by an ejection head. The heating element includes a
conductive material deposited onto an insulative substrate, a
protective layer deposited onto the conductive layer, and a porous
layer having a porosity of at least about 50% deposited onto the
protective layer. The heating element has an effective surface area
(ESA) for fluid vaporization that is greater than a planar surface
area defined by dimensions of the heating element so that a fluid
contact surface of the heating element is greater than the planar
surface area of the heating element.
[0005] In one embodiment, the heating element has a rectangular
shape. Accordingly, the effective surface area (ESA) of the heating
element is defined by the equation ESA>L.times.W, wherein L is a
length of the heating element and W is a width of the heating
element that is exposed to a vaporizing fluid.
[0006] In another embodiment, the heating element has a circular
shape. Accordingly, the effective surface area (ESA) of the heating
element is defined by the equation ESA>.pi..times.R.sup.2
wherein R is a radius of the heating element that is exposed to a
vaporizing fluid.
[0007] Another embodiment of the disclosure provides a vaporizing
device that includes a housing body, a mouthpiece attached to the
housing body, and a heating element disposed adjacent to the
mouthpiece for vaporizing fluid ejected from an ejection head. The
heating element has a conductive material deposited onto an
insulative substrate, a protective layer deposited onto the
conductive layer, and a porous layer having a porosity of at least
about 50% deposited onto the protective layer.
[0008] A further embodiment of the disclosure provides a method for
vaporizing a fluid ejected by an ejection head so that
substantially all of the fluid ejected by the ejection head is
vaporized. The method includes providing a vaporization device
having an ejection head and a vaporizing heater element adjacent to
the ejection head; ejecting fluid onto the heater element;
activating the heating element during fluid ejection; and
vaporizing substantially all of the fluid using the heating
element. The heating element has a conductive material deposited on
an insulative substrate, a protective layer deposited on the
conductive layer, and a porous layer having a porosity of at least
about 50% deposited onto the protective layer.
[0009] In some embodiments, the porous layer has a grit blasted
surface texture that provides the effective surface area (ESA)
thereof. In other embodiments, the porous layer is a grit blasted
ceramic material.
[0010] In another embodiment, the porous layer is a laser etched
ceramic layer.
[0011] In yet another embodiment, the porous layer is deposited as
a coarse glass frit that is sintered onto a surface of the heating
element.
[0012] In some embodiments, the porous layer has a thickness
ranging from about 0.5 millimeters (mm) to about 3 mm. In other
embodiments the porous layer has a thickness ranging from about 1
mm to about 2 mm.
[0013] In some embodiments, the insulative substrate, conductive
layer and protective layer have a combined thickness ranging from
about 4 millimeters (mm) to about 1 centimeter (cm)
[0014] In some embodiments, the porous layer has a porosity ranging
from about 50% to about 95%.
[0015] In some embodiments, the conductive layer is a screen
printed conductive layer deposited onto a ceramic substrate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Other features and advantages of disclosed embodiments may
be evident by reference to the following detailed description,
drawings and claims wherein:
[0017] FIG. 1 is a cross-sectional view, not to scale, of a
vaporization device according to an embodiment of the
disclosure.
[0018] FIG. 2 is a close-up view, not to scale, of a portion of the
vaporization device of FIG. 1.
[0019] FIG. 3 is a cross-sectional view, not to scale, of a heating
element according to an embodiment of the disclosure.
[0020] FIG. 4 is a cross-sectional view, not to scale, of a heating
element according to another embodiment of the disclosure.
[0021] FIGS. 5-7 are schematic views, not to scale, of a process
for making a heating element according to an embodiment of the
disclosure.
[0022] FIG. 8 is a cross-sectional view, not to scale, of a heating
element having fluid absorbed into an upper porous surface
according to an embodiment of the disclosure.
DETAILED DESCRIPTION OF EMBODIMENTS
[0023] The disclosure is directed to a vaporization device 10 as
shown in FIGS. 1 and 2 and heating elements therefor as shown in
FIGS. 3-8. Such devices 10 may be used for a wide variety of
applications wherein a liquid is ejected onto a heating element to
provide a vapor stream as described in more detail below. Such
devices 10 are typically hand held devices such as electronic
cigarettes that have a mouthpiece 12 for inhaling vapors generated
by the device 10. The mouthpiece 12 includes a conduit 14 for flow
of vapors out of the device 10. The main components of the device
10 include a housing body 16, a removable cartridge cover 18, a
removable fluid supply cartridge 20, an ejection head 22 associated
with the fluid supply cartridge 20, and a heating element 24 and
holder therefor 26 for vaporizing fluid ejected from the ejection
head 22. Other components associated with the vaporization device
10 include a rechargeable power supply 28, a main circuit board 30,
and a vaporization driver card 32. An enlarged portion of the
vaporization device is shown in FIG. 2.
[0024] The mouthpiece 12, as well as the body 16 of the
vaporization device 10 may be made from a wide variety of materials
including plastics, metals, glass, ceramic and the like provided
the materials are compatible with the fluids to be ejected and
vaporized by the device 10. A particularly suitable material may be
selected from polyvinyl chloride, high density polyethylene,
polycarbonate, stainless steel, surgical steel, nickel-plated
steel, and the like. All parts, including the mouthpiece 12, and
body 16 that come in contact with fluids and vapors may be made of
plastic. The conduit 14 may be made of metal such as stainless
steel or other material that is resistant to heat and vapors
generated by the device.
[0025] As shown in FIG. 1, the housing body 16 may include the
circuit board 30 and the driver card 32 for providing the logic
circuitry for the heating element 24 (described in more detail
below) and ejection head 22. The rechargeable battery 28 may also
be housed in the housing body 16. In another embodiment, a
removable, non-rechargeable battery may be housed in the housing
body. Electrical contacts, such as a USB (not shown) may be used to
recharge the battery 28 and to change program setting for the
ejection head 22 and heating element 24. The microfluidic ejection
head 22 is in fluid flow communication with the fluid supply
cartridge 20 that provides fluid to be ejected by the ejection head
22.
[0026] An inlet air flow control device may be included to provide
backpressure control on the ejection head 22. The inlet air flow
control device may include a damper slide 34 and air inlet holes 36
that allow air to be drawn into the conduit 14 adjacent the heating
element 24 and ejection head 22 so that excessive negative pressure
on the ejection head 22 can be avoided.
[0027] An important component of the vaporization device 10 is the
heating element 24 as shown in FIG. 3. The heating element 24 is
typically made of a high temperature solid ceramic base 40 having a
resistive or conductive material 42 printed thereon, deposited
thereon, or otherwise imbedded in the ceramic base 40. The
resistive or conductive material may be selected from a wide
variety of materials typically used for heating elements including,
but not limited to, silver and/or carbon screen printed materials,
as tungsten, molybdenum, molybdenum-manganese, and the like.
[0028] As set forth above, it is desirable to vaporize
substantially all fluid ejected from the ejection head 22 so that
only vapors are discharged through the conduit 14 of the mouthpiece
12. Accordingly, the heating element 24 desirably contains a fluid
absorbing or capturing layer 44 that is formed on a protective
layer 46. The protective layer 46 is positioned between the fluid
absorbing or capturing layer 44 and the resistive or conductive
metal material 42 and may be made of the same material as the
ceramic base 40 or any other suitable, high temperature material
that is substantially non-porous. Other suitable materials for the
protective layer include, but are not limited to alumina, aluminum
nitride, silica or silicon nitride.
[0029] The overall thickness T1 of the heating element may range
from about four millimeters to about 1 centimeter. The thickness T2
of the fluid absorbing or capturing layer 44 may range from about
0.5 to about 3 millimeters in thickness, such as from about 1 to
about 2 millimeters in thickness. The thicknesses of the resistive
or conductive material 42 and protective layer 46 are not critical
to the embodiments of the disclosure. In the case of an imbedded
resistive or conductive material 42, a protective material layer 46
may not be necessary.
[0030] In one embodiment, as shown in FIG. 3, layer 44 is a porous
layer having a porosity of at least about 50% that is deposited
onto the protective layer 46. In another embodiment, the porosity
of layer 44 may range from about 60% to about 85%. Having a
porosity of at least about 50% means that the layer 44 is porous or
has indentations or cavities that provide at least 50% void space
volume relative to the entire volume of layer 44. The porosity
range is based on engineering judgement as the practical limits for
a porous layer. The mass of the layer 44 is as small as possible to
optimize warm up speed and minimize power consumption for heating
the layer 44. Low mass requires a high porosity with 95% chosen as
a realistic upper limit. Above 95% porosity the structure would be
too weak and difficult to fabricate. A 50% porosity is chosen as
the minimum porosity for layer 44. Below 50% porosity wicking
properties of layer 44 will suffer due to closed off/inaccessible
pores in the structure.
[0031] For a rectangular heating element having a width W, a length
L and a thickness T1 as described above, the heating element 24 is
further defined as having an effective surface area (ESA) for fluid
vaporization that is defined by the equation ESA>L.times.W. For
a circular heating element, the effective surface area (ESA) of the
heating element is defined by the equation
ESA>.pi..times.R.sup.2 wherein R is a radius of the heating
element that is exposed to a vaporizing fluid. The heating element
is not limited to a rectangular or circular shape as any shape
including triangular, complex shapes, and the like may be used.
Accordingly, the ESA of the heating element is greater than the
nominal dimensions of the protective layer 46.
[0032] In another embodiment, as shown in FIG. 4, a grit blasted
ceramic layer or a laser etched ceramic layer 48 may be used to
capture the fluid ejected from the ejection head 22. Accordingly, a
ceramic layer 48 may be applied to the protective layer 46 and then
grit blasted or laser etched to form indentations 50 in the ceramic
layer 48 that significantly increase the effective surface area of
the heating element 24 as shown. In an alternative embodiment, the
protective layer 46 itself may be grit blasted or laser etched as
opposed to adding and blasting or etching layer 48. The grit
blasted or laser etched surface of layer 48 or protective layer 46,
like the porous layer 44, may be effective to prevent pooling of
liquid on the surface thereof and may provide more rapid
vaporization of fluid ejected onto the heating element 24.
[0033] One method for making a heating element 24, according to an
embodiment of the disclosure, is illustrated schematically in FIGS.
5-7. The heating element 24 includes a ceramic material 40 that
contains a high melting point metal heating material such as
tungsten, molybdenum, or molybdenum-manganese embedded in a 92 to
96% by weight alumina ceramic substrate 40 to from the conductive
layer 42. For example, a metal heating resistance slurry of one or
more of the foregoing metals may be printed onto a tape casting of
a ceramic green body to form the conductive layer 42. Several
layers of ceramic green body are then laminated together at a high
temperature with the aid of 4 to 8% by weight of a sintering
additive to form an alumina ceramic heating substrate 40. Materials
for the ceramic substrate 40 include, but are not limited to
aluminum nitride and cubic boron nitride.
[0034] In a next step of the process, as shown in FIG. 6, a layer
of glass frit is applied to a the protective layer 46 that is
applied to the conductive layer 46 to provide layer 54. The glass
frit may be applied as a screen printed paste or slurry to the
surface of the heating element 24.
[0035] In the final step of the process, FIG. 7, the glass frit is
sintered while on the heating element 24 to provide a porous
surface 56 having a thickness ranging from about 0.5 millimeters to
about 3 millimeters, such as from about 1 millimeter to about 2
millimeters. Upon ejecting fluid from the ejection head 22 onto the
heating element 24, the fluid is absorbed by the sintered glass
frit layer to form a fluid containing porous layer 58 (FIG. 8). The
fluid containing layer 58 provides increased effective heating
element surface area so that more efficient evaporation of the
liquid may take place.
[0036] While particular embodiments have been described,
alternatives, modifications, variations, improvements, and
substantial equivalents that are or can be presently unforeseen can
arise to applicants or others skilled in the art. Accordingly, the
appended claims as filed and as they can be amended are intended to
embrace all such alternatives, modifications variations,
improvements, and substantial equivalents.
* * * * *