Title of Invention

AN ELECTROSTATIC ATOMISER

Abstract An electrostatic atomiser (1), comprises a channel (3) through which, in use, a fluid passes; one or more orifices (8) to allow the fluid to exit the atomiser (1); and at least two electrodes (4, 6) in contact with the fluid, when the atomiser is in use, so that when an appropriate potential is applied to said electrodes (4, 6), fluid particles are charged; at least one of said electrodes (4, 6) presents a fluid contacting region which comprises a closely contiguous array of non-fibrous conducting elements (13) generally protruding from the electrode (6) so as to form an array of individual electrode points where the field generated by the atomiser is concentrated.
Full Text AN ELECTROSTATIC ATOMISER
Field of the Invention
The invention relates to electrostatic atomisers applied in any practical system
where the atomisation of fluid is required. It may be for example employed in
a system for the supply of combustion fuel, liquid solutions in say the delivery
of drugs, cosmetic fluids and other synthesized solutions in say household
sprays. The invention as set out in this application is not limited to any of
these particular applications and is intended to be applicable to any atomiser
which falls within the scope of the claims which are included at the end of this
application.
Prior Art known to the Applicant(s)
The present inventive concept is generally concerned with improving
atomisation in electrostatic atomisers by proposing radical departures from the
prior art known to the applicant and detailed herein.
Typically, prior art atomisers comprise a central electrode, an outer electrode
located around said central electrode, and sufficiently spaced from one another
to form a channel in which fluid particles are charged prior to exiting through
orifices. In this configuration, a high potential is customarily applied to the
central electrode whilst the outer electrode is grounded. Reversing these
potentials - i.e. applying the high potential to the outer electrode — is not
practical as in its environment there would be either the risk of electrocution
should an operator inadvertently touch the outer electrode or the superfluous
requirement of incorporating an additional insulating layer such as a ceramic
sheath which would add unnecessary complexity. Consequently, prior art
systems exclusively apply the high potential to the central electrode not to the
outer electrode.
Figure 1 shows some of the constraints under which prior art atomisers
operate. Atomisation is a balance between maximum voltage potential,
percentage of potential charge retained in the discharged fluid and the
electrode gap (distance separating the electrodes). In prior art systems as the
electrode gap is increased the maximum voltage potential may be increased
but the critical percentage of potential charge retained in the discharged fluid
is reduced, thus resulting in relatively poor atomisation beyond a given
electrode gap for a given atomiser.
One of the objectives of the present invention is to offer a radically different
approach to atomisation which would to a large extent remove the strict
barriers of design to which prior art systems are generally constrained.
Within the present inventive concept, other more specific prior art systems are
deemed to be relevant and are detailed as follows.
One type of known prior art teaches the use of a single central electrode in an
atomisation system terminating in a sharp point at its fluid interface so as to
generate a relatively high electrical field about that point. One example of
such a system is disclosed in US patent number 6,206,307 (Arnold J Kelly)
where an electrode protrudes into a passing fluid in the form of a generally
conical tip. This, patent discloses in its section which provides a detailed
description of the figures that the tip is formed from a fibrous material having
electrically conductive fibres extending generally in the axial direction of the
electrode and of the body, each such fibre having a microscopic point, these
points co-operatively constituting the surface of the tip. The surfaces defining
the orifice are deprived of any such fibres and are even preferably required to
be smooth. This particular atomiser generally terminates in a point which for
adequate performance requires to be precisely aligned with its orifice 22.
Consequently, strict concentricity tolerances are required to be applied during
its manufacturing. Furthermore, if for any reason, the alignment of the tip
with its orifice is altered during the lifecycle of the atomiser efficiency will
unavoidably suffer.
Another fibrous tip is disclosed in a separate US patent number 4,627,903
(Alan T Chapman) which discloses the use of composite fragments in the
sharp point electrode tip containing sub-micron metallic fibres uniformly
arrayed in a non-conducting (insulating) matrix.
Another type of prior art system discloses electrode tips terminating in a bell
shape (with an annular sharp edge). This configuration is usually utilised in
atomisers incorporating circumferentially arrayed orifices. One example of
such a configuration can be seen in Figure 2 in a paper presented by A. J.
Kelly circa July 1998 at DOE (Diesel Engine Emissions Workshop). Another
example of such an electrode configuration is disclosed in US patent number
5,725,151 (Robert Hetrick).
Each of these bell shaped electrodes has similar stringent concentricity
tolerances requirements to the above presented conical electrodes.
Every prior art configuration referenced above requires strict tolerances to be
achieved and precise electrode tip geometry to be selected for given orifice
arrangements.
One of the objectives of the present invention is to provide an atomiser whose
electrode"s geometry may be applied to a wide variety of orifice
configurations. The present invention therefore aims to provide an altogether
more flexible system with less stringent requirements for tolerances and of tip
geometry.
A further objective of the invention is to provide an atomiser whose design
and manufacture is carried out with improved freedom and which will also be
particularly well suited to high volume production.
A further objective of the invention is to provide an atomiser with improved
atomisation properties both for single orifice atomisers and multi-orifice
atomisers.
Summary of the Invention
In its first broad independent aspect, the invention presents an electrostatic
atomiser, comprising a channel through which, in use, a fluid passes; one or
more orifices to allow the fluid to exit the atomiser; and at least two electrodes
in contact with the fluid, when the atomiser is in use, so that when an
appropriate potential is applied to said electrodes, fluid particles are charged;
characterised by the fact that at least one of the said electrode presents a fluid
contacting region which comprises a closely contiguous array of non-fibrous
conducting elements generally protruding from the electrode so as to form an
array of individual electrode points where the field generated by the atomiser
is concentrated.
This configuration is advantageous because it removes the complex
requirements of having to precisely align the electrode tip with a particular
orifice. Furthermore, a multi-orifice atomiser may in this configuration be
produced with a relatively high radius tip instead of the prior art system where
the electrode tip terminates in a sharp point or a sharp perimeter edge in the
case of the bell shaped tip. This configuration will also achieve an
advantageously even atomised spray from its orifices. Its manufacturing will
also be simplified as compared to the previously discussed prior art systems.
In a second broad independent aspect, the invention covers an electrostatic
atomiser, comprising a channel through which, in use, a fluid passes; one or
more orifices to allow the fluid to exit the atomiser; and at least two electrodes
in contact with the fluid, when the atomiser is in use, so that when an
appropriate potential is applied to said electrodes, fluid particles are charged;
characterised by the fact that at least one of said electrodes presents a fluid
contacting region which comprises one or more faceted conducting elements.
Similar advantages to those listed with regard to the first broad independent
aspect apply to the second broad independent aspect above. These advantages
are also present even when the atomiser only comprises a single faceted
conducting element Faceted conducting elements have the additional benefits
of being generally particularly hard wearing and therefore particularly
advantageous in atomising high frequency injected fluids and also particularly
when applied in systems where the atomisation is followed by an explosion of
the atomised fluid.
In a third broad independent aspect, an electrostatic atomiser, comprises a
channel through which, in use, a fluid passes; one or more orifices to allow the
fluid to exit the atomiser; and at least two electrodes in contact with the fluid,
for charging fluid particles when the atomiser is in use, wherein the or each
orifice is part of an electrode to which a high potential is applied in use and
said electrode presents a fluid contacting region which comprises a closely
contiguous array of conducting elements generally protruding from the
electrode so as to form an array of individual electrode points where the field
generated by the atomiser is concentrated.
This configuration marks a radical departure from the prior art thinking that
the electrode surface at the orifice is to be preferably smooth. This aspect
teaches literally the opposite. It also considers applying the high potential to
the orifice electrode. By so doing, many of the prior art constraints are lifted.
Particular advantages of this configuration are presented in Figure 2, where
strict compliance to a given range of electrode gap as was the requirement of
systems according to figure 1, is no longer a requirement. The percentage of
potential charge retained in the discharge fluid is high almost irrespective of
the electrode gap. Atomisation is therefore improved and achievable over a
larger range of geometries as compared to the prior art systems.
Furthermore, the advantages disclosed with reference to the first and second
broad independent aspect are also present in this configuration.
In a fourth broad independent aspect, an electrostatic atomiser, comprising a
channel through which, in use, a fluid passes; one or more orifices to allow the
fluid to exit the atomiser; and at least two electrodes in contact with the fluid
for charging fluid particles when the atomiser is in use, wherein the or each
orifice is part cf an electrode to which a high potential is applied in use and
said electrode presents a fluid contacting region which comprises one or more
faceted conducting elements.
Similar advantages are present in this configuration as those presented in the
context of the previous broad independent aspects. The specific advantages of
the third broad independent aspect are also present when a single faceted
conducting element is located in the fluid contacting region of an orifice.
In a subsidiary aspect in accordance with any of the preceding broad
independent aspects, the elements are diamond compounds or are carbon
based compounds having similar properties to diamond. Utilising diamonds
or the like compounds is particularly advantageous because of the combination
of properties of diamond compounds - particularly when considering their
toughness, electrical conductivity and ability of being retained by the electrode
itself.
In a further subsidiary aspect, the elements form part of a diamond coating. A
diamond coating is particularly advantageous as it may readily be applied to a
wide variety of electrode geometries and is particularly well suited to high
volume production.
In a further subsidiary aspect, the elements are fullerene molecules. These
often have an icosahedral or a so-called "soccer ball" configuration constituted
of an even-numbered clusters of Cin species with m>40. This configuration
has a surprisingly advantageous effect on atomisation despite its relative
smoothness when compared to diamond crystals.
In a further subsidiary aspect, the elements are carbon 64 compounds. This
additional feature is particularly advantageous as its application achieves
improved atomisation and renders the system flexible and suitable for high
volume production."
In a further subsidiary aspect, the size of one or more elements is under 500
microns. Below this size, the atomiser configuration becomes advantageously
flexible doing away with the prior art stringent tolerance requirements and
restrictions as to the electrode"s geometry.
Advantageously, the size of one or more elements may be comprised within
the range of 10 to 150 microns. At these levels, flexibility is even further
improved while maintaining advantageous atomisation properties. The cost of
manufacturing atomisers within this range is also particularly beneficial.
In a further subsidiary aspect, a first electrode incorporates an array of said
orifices and a second electrode is spaced from said first electrode to permit the
passage of fluid between them, the fluid contacting surface of said second
electrode incorporating an array of said elements located essentially over said
array of orifices. One of the advantages of this particular configuration is that
atomisation is further improved by being particularly well balanced between
the atomiser"s various orifices.
Advantageously, the second electrode"s surface provided over the or each
section located between orifices may be deprived of said elements. Adapting
the atomiser in this manner reduces the amount of elements necessary to
achieve improved atomisation and is equally susceptible of being produced in
high volumes.
In a further subsidiary aspect, a first electrode incorporates an array of said
orifices and a second electrode is spaced from said first electrode to permit the
passage of fluid between them, the first electrode incorporating in addition an
array of elements.
In this configuration, a higher concentration of electrical fields at the orifices may be
achieved which would result in an improvement of the atomization properties.
Advantageously, the or each orifice may be adapted to achieve an essential radial flow and
the array of elements may take the form of a ring spaced from the or each orifice to permit
the passage of fluid through the or each orifice and located essential over the or each orifice.
The configuration is advantageous because as it may be able to wrap around an object while
still improving the atomization of a fluid whilst doing away with the constraints of the prior
art, particularly as to concentricity tolerances evident when using bell shaped electrode tips.
Brief Description of the Accompanying Figures
Figure 1 shows the characteristics of a prior art system.
Figure 2 shows the characteristics of an inventive configuration.
Figure 3 shows a schematic cross-sectional view of part of an illustrative atomizer in
accordance with a first embodiment of the present invention.
Figure 4 shows a further schematic cross-sectional view of part of an atomizer in accordance
with a second embodiment of the invention.
Figure 5 illustrates a further cross-sectional view of part of an atomizer according to a third
embodiment of the invention.
Figure 6 represents a further cross-sectional view of part of an atomizer according to a
fourth embodiment of the invention.
Figure 7 shows a cross-sectional view of part of an atomizer in accordance with a fifth
embodiment of the invention.
Figure 8 shows a cross-sectional view of part of an atomiser in accordance
with a sixth embodiment of the invention.
Figure 9 shows a cross-sectional view of part of an atomiser in accordance
with a seventh embodiment of the invention.
Detailed Description of the Figures
Figure 1 and figure 2 are discussed in detail in the context of the previous
sections.
Figure 3 shows an electrostatic atomiser generally referenced 1. The atomiser
operates in conjunction with a fluid supply system 2 which conducts fluid into
the atomiser first through a fluid passage 3 annular and essentially concentric
with the longitudinal axis of the atomiser. Fluid passage 3 is formed between
wall 4 and insulator 5. The insulator wraps about the outer surface of a central
electrode 6 so as to electrically isolate the fluid in passage 3 from the central
electrode 6.
After the fluid passage 3, the fluid enters an atomisation chamber 7.
In the lower region of wall 4, there is provided an array of orifices such as that
referenced 8.
A high voltage power source 9 is connected to both central electrode 6 and
wall 4. Power source 9 is not intended in any way to be limited to any
particular configuration and may for example be a direct current (DC) or even
an alternative current (AC) power source. The person skilled in the art will
naturally select an appropriate potential to be applied and any beneficial time
dependencies, if necessary, from known alternatives. It is also envisaged
within the scope of the invention that the electrodes with which the power
source is to operate may be either positive or negative electrodes. Any such
modification will undoubtedly be self-evident to the skilled addressee of this
application and are therefore not detailed any further for the purposes of this
description.
The central electrode 6 has the characteristic of terminating in a high radius
curve covered by a diamond coating 10 covering the entire fluid contacting
surface of the electrode.
The diamond costing 10 is constituted of diamond elements of say 10 microns
such as that referenced 11 which protrudes from the electrode so as to form an
electrode point 12. At this element size, the manufacturing process involved
in coating may be a mechanical adhesion process whereby a fixer shown as
layer 13 in the figure is first applied onto the surface of the electrode followed
by the deposition of the array of elements 11. The person skilled in the art
may also coat the electrode by other known processes such as plasma or gas
deposition. The plasma deposition process will be particularly envisaged for
element depositions in the nano-scale.
Alternatively, elements 11 may be replace by carbon 64 compounds such as
that referenced 14 in the figure. Element 14 may be of general spherical shape
and protrudes from the electrode so as to form individual electrode points
which achieve the advantageous field concentration required for improved
atomisation.
The invention also envisages the use of a so-called "diamond like" coating.
This may be a carbon based compound having similar properties (for example
hardness) to diamond.
The invention also envisages that the elements of the same material as the
electrode itself by for example etching away specific sections of the
electrode"s surface so that elements are formed which protrude from the
electrode and are part of an array of individual electrode points to concentrate
the field generated by the atomiser.
Figure 4 represents an electrostatic atomiser where identical components to
those used in Figure 2 are given the same numerical reference followed by a
prime sign. A distinctive feature of this embodiment is the incorporation of a
diamond coating 15 on the inner surface of wall 4". In addition, a high
potential is intended to be applied to wall electrode 4" by power source 9"
whilst the central electrode may be grounded. While a diamond coating 15 is a
preferred configuration of atomiser 1", it may be in fact also constituted of
fibrous conductive material selected by the person skilled in the art to generate
a concentration of potential charge which would be transmitted to fluid
particles as they exit the atomiser. In the context of this application fluid
particles naturally extend to any parts or elements of a fluid including the
actual molecules or atoms of said fluid.
In this configuration atomisation occurs particularly evenly through each
orifice. One of the results of this configuration is shown as previously
discussed in Figure 2.
Figure 5 shows a further embodiment of an atomiser generally referenced 16
with a central electrode 17, an insulator 18 and a wall 19. Central electrode 17
has the particularity of terminating in a conical tip 20 incorporating an array of
elements disposed in a coating of diamond 21.
Figure 6 shows a further atomiser generally referenced 22 with a power source
23 applying a difference in potential between a central electrode 24 and a wall
electrode 25 in order to charge fluid particles travelling between them. Three
orifices such as that referenced 26 are represented in the figure. A region of
elements in for example a diamond coating are located directly over orifice 26
and is referenced 27. A second region 28 is located directly over orifice 29
whilst a third region 30 is located directly over orifice 31. The portions
located directly over the sections located between the orifices such as that
referenced 32 are deprived of elements. This configuration achieves enhanced
atomisation while at the same "time reducing the amount of elements required
to achieve this kind of multi-orifice atomisation.
Figure 7 represents an atomiser 33 with a central electrode 34 and a wall
electrode 35 provided with orifice 36 capable of achieving essentially radial
flow. Around the lower region of central electrode 34, there is provided a ring
37 of elements which allows the field generated by the atomiser to be evenly
concentrated in any radial direction.
Figure 8 shows a further atomiser 38 with a fluid supply system 39 and a
power source 40. Power source 40 applies a relatively high voltage on outer
electrode 41 whilst a low potential is applied to central electrode 42. The
outer electrode 41 incorporates a number of orifices respectively referenced
43, 44 and 45. On the inner surface of outer electrode 41, there are provided
portions of elements 46, 47 and 48. Each of these portions of elements forms
a ring around the inlet of the various orifices. The inner surface of outer
electrode 41 between these portions is deprived of any such elements.
Figure 9 represents an atomiser 49 which incorporates three electrodes 50, 51
and 52. An electrical insulator 53 may be provided between electrodes 50 and
51. Such a configuration may be electrically connected in a variety of modes.
One of the modes of electrical connection would be to ground electrode 52
whilst a very high potential (eg. 30 to 40 kV) is applied to electrode 50 and a
high potential (eg. 6 to 10 kV) is applied to electrode 51. Another mode of
connection would be to supply a very high potential of for example 30 to 40
kV to the outer electrode 52, whilst a high potential of 6 to 10 kV is applied to
electrode 51 and electrode 50 is grounded. A further mode of operation would
be to apply a high potential to electrode 52 whilst electrodes 50 and 51 are
grounded. In this embodiment, element portion 54 is located adjacent to
orifice 55. It is envisaged within the scope if the invention mat element
portions such as that referenced 54 may be used at any appropriate location in
the atomiser"s exit path.
We claim:
1. An electrostatic atomizer, comprising a channel through which a fluid can pass;
one or more orifices to allow the fluid to exit the atomizer; and at least two
electrodes, contactable with the fluid, so that when an appropriate potential is
applied to said electrodes, fluid particles are charged; characterized by the fact that
at least one of said electrode presents a fluid contacting region which comprises a
contiguous array of non-tibrous conducting elements generally protruding from the
electrode so as to form an array of individual electrode points where the field
generated by the atomizer is concentrated.
2. An electrostatic atomizer, comprising a channel through which a fluid can pass;
one or more ormces, to allow me fluid to exit the atomizer; and at least two
electrodes, contactable with the fluid, so that when an appropriate potential is
applied to said electrodes, fluid particles are charges; characterized by the fact that
at least one of said electrode presents a fluid contacting region which comprises
one or more faceted conducting elements.
3. An electrostatic atomizer, comprising a channel, through which a fluid can pass;
one or more orifices to allow the fluid to exit the atomizer; and at least two
electrodes contactable with the fluid for charging fluid particles, characterized in
that the or each orifice is part of an electrode to which a high potential can be
applied and said electrode presents a fluid contacting region which comprises a
contiguous array of conducting elements generally protruding from the electrode
so as to form an array of individual electrode points where the field generated by
the atomizer is concentrated.
4. An electrostatic atomizer, comprising a channel through which a fluid can pass;
one or more orifices to allow the fluid to exit the atomizer; and at least two
electrodes contactable with the fluid for charging fluid particles, characterized in
that the or each orifice is part of an electrode to which a high potential can be
applied and said electrode presents a fluid contacting region which comprises one
or more faceted conducting elements.
5. An atomizer as claimed in any preceding claim, wherein the elements are diamond
compounds.
6. An atomizer as claimed in any preceding claim, wherein the elements are carbon
based with similar properties to diamond.
7. An atomizer as claimed in any preceding claim, wherein the elements form part of
a diamond coating.
8. An atomizer as claimed in any preceding claim, wherein the elements are fullerene
molecules.
9. An atomizer as claimed in any preceding claim, wherein the elements are Carbon
64 compounds.
10. An atomizer as claimed in any preceding claim, wherein the size of one or more
elements is under 500 microns.
11. An atomizer as claimed in claim 7, wherein the size of one or more elements is
comprised within the range of 10 to 150 microns.
12. An atomizer as claimed in any preceding claim, wherein a first electrode
incorporates an array of said orifices and a second electrode is spaced from said
first electrode to permit the passage of fluid between them, the fluid contacting
surface of said second electrode incorporating an array of said elements located
essentially over said array of orifices.
13. An atomizer as claimed in claim 12, wherein the second electrode"s surface
provided over the or each section located between orifices is deprived of said
elements.
14. An atomizer as claimed in claims 1, 2 and 5 to 11, wherein a first electrode,
incorporates an array of said orifices ana a second electrode is spaced from said
first electrode to permit the passage of fluid between them, the first electrode
incorporating in addition any array of elements.
15. An atomizer as claimed in any preceding claim, wherein the or each orifice is
adapted to achieve an essentially radial flow and the array of elements takes the
form of a ring spaced from the or each orifice to permit the passage of fluid
through the or each orifice and located essentially over the or each orifice.
16. An atomizer as hereinbefore described with reference to an/or illustrated in any
appropriate combination of the accompanying text and/or drawings.
An electrostatic atomizer (1), comprises a channel (3) through which, in use, a fluid
passes; one or more orifices (8) to allow the fluid to exit the atomizer (1); and at least two
electrodes (4, 6) in contact with the fluid, when the atomizer is in use, so that when an
appropriate potential is applied to said electrodes (4, 6), fluid particles are charged; at
least one of said electrodes (4, 6) presents a fluid contacting region which comprises a
closely contiguous array of non-fibrous conducting elements (13) generally protruding
from the electrode (6) so as to form an array of individual electrode points where the field
generated by the atomizer is concentrated.

Documents:

01674-kolnp-2005-abstract.pdf

01674-kolnp-2005-claims.pdf

01674-kolnp-2005-description complete.pdf

01674-kolnp-2005-drawings.pdf

01674-kolnp-2005-form 1.pdf

01674-kolnp-2005-form 3.pdf

01674-kolnp-2005-form 5.pdf

01674-kolnp-2005-international publication.pdf

1674-kolnp-2005-granted-abstract.pdf

1674-kolnp-2005-granted-assignment.pdf

1674-kolnp-2005-granted-claims.pdf

1674-kolnp-2005-granted-correspondence.pdf

1674-kolnp-2005-granted-description (complete).pdf

1674-kolnp-2005-granted-drawings.pdf

1674-kolnp-2005-granted-examination report.pdf

1674-kolnp-2005-granted-form 1.pdf

1674-kolnp-2005-granted-form 13.pdf

1674-kolnp-2005-granted-form 18.pdf

1674-kolnp-2005-granted-form 2.pdf

1674-kolnp-2005-granted-form 3.pdf

1674-kolnp-2005-granted-form 5.pdf

1674-kolnp-2005-granted-letter patent.pdf

1674-kolnp-2005-granted-pa.pdf

1674-kolnp-2005-granted-reply to examination report.pdf

1674-kolnp-2005-granted-specification.pdf

abstract-01674-kolnp-2005.jpg


Patent Number 216059
Indian Patent Application Number 01674/KOLNP/2005
PG Journal Number 10/2008
Publication Date 07-Mar-2008
Grant Date 06-Mar-2008
Date of Filing 22-Aug-2005
Name of Patentee SCION SPRAYS LIMITED
Applicant Address NORWICH RESEARCH PARK, COLNEY, NORWICH NR4 7UT
Inventors:
# Inventor's Name Inventor's Address
1 ALLEN, JEFFREY 4 SHEPPARD WAY, ATTLEBOROUGH, NORFOLK NR17 2DQ
PCT International Classification Number B05B 5/053
PCT International Application Number PCT/GB2004/000458
PCT International Filing date 2004-02-06
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 0303158.0 2003-02-12 U.K.