U.S. patent number 3,679,132 [Application Number 05/004,595] was granted by the patent office on 1972-07-25 for jet stream vibratory atomizing device.
This patent grant is currently assigned to Cotton, Incorporated. Invention is credited to Jay G. Porterfield, Lawrence O. Roth, Dennis A. Vehe.
United States Patent |
3,679,132 |
Vehe , et al. |
July 25, 1972 |
JET STREAM VIBRATORY ATOMIZING DEVICE
Abstract
In a jet stream vibratory atomizing device including a nozzle
body and a nozzle head attached to the nozzle body, a selectively
variable constant pressure source of fluid is connected into the
nozzle body such that fluid may be force through an opening or
openings fashioned in the nozzle head. A volumetric displacement
member is positioned to contact the fluid within the nozzle body
near the head. High rate cyclic disturbances are transmitted from
the volumetric displacement member through the fluid downstream of
the openings in the head to induce a uniform formation of droplets
in the fluid stream wherein the number of droplets formed
corresponds to the rate of displacement of the volumetric
displacement member.
Inventors: |
Vehe; Dennis A. (Mineral Wells,
TX), Porterfield; Jay G. (Stillwater, OK), Roth; Lawrence
O. (Stillwater, OK) |
Assignee: |
Cotton, Incorporated (New York,
NY)
|
Family
ID: |
21711549 |
Appl.
No.: |
05/004,595 |
Filed: |
January 21, 1970 |
Current U.S.
Class: |
239/4; 347/1;
239/102.2 |
Current CPC
Class: |
B05B
17/0646 (20130101); B05B 1/083 (20130101); B05B
17/0607 (20130101); B05B 17/0638 (20130101) |
Current International
Class: |
B05B
1/08 (20060101); B05B 1/02 (20060101); B05B
17/04 (20060101); B05B 17/06 (20060101); B05b
017/04 () |
Field of
Search: |
;239/102,101,4,99,585,590.3 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Wood, Jr.; M. Henson
Assistant Examiner: Grant; Edwin D.
Claims
We claim:
1. A process for jet stream dispensing a biological control agent
by atomizing the control agent into generally uniform droplets
comprising the steps of:
delivering a biological control agent to be atomized into a
generally tubular nozzle body having one end thereof sealed and a
nozzle head covering the other end thereof with at least one fluid
jetting opening therethrough;
jetting the biological control agent through the at least one
opening by pressurizing the biological control agent within the
nozzle; and
imparting a high frequency vibration to the biological control
agent for breaking the jet of biological control agent downstream
of the opening into generally uniform droplet size.
2. A process as defined in claim 1 wherein said step of imparting a
high frequency vibration to the biological control agent
comprises:
cyclically magnetizing a magnetostrictive shaft having one end
thereof extending interiorly within the nozzle body.
3. A process as defined in claim 1 wherein said biological control
agent comprises a herbicide.
4. A process as defined in claim 1 wherein said biological control
agent comprises a pesticide.
Description
BACKGROUND OF THE INVENTION
This invention relates to a process and apparatus for jet stream
atomizing a fluid into droplets of uniform size and at a
controllable rate. More particularly this invention relates to
improvements in the process and apparatus for atomizing liquid
pesticides, herbicides, growth or ripening control agents and the
like.
The process of atomization is of primary importance in several
branches of engineering, such as in the combustion of liquid fuels,
in the chemical industry in operations involving drying,
evaporation and absorption, in fire fighting for the production and
dissipation of fogs, in agriculture for crop protection, etc.
Atomization of a fluid may be accomplished by forcing a fluid under
pressure through a restriction into the atmosphere where the fluid
breaks up into droplets. These droplets, however, are formed in
various sizes. As an example, conventional spray nozzles which
would be designed to produce droplets having a mean diameter of 150
microns would generate droplets ranging in size from 1 or 2 microns
to 300 or 400 microns in diameter. In many applications this range
of droplet sizes is not particularly unacceptable. However, in
numerous applications, particularly in agriculture, a more uniform
droplet size would be highly desirable.
There has been an increasing utilization of herbicides and
pesticides in large-scale agriculture. They are applied either from
ground spraying booms and rigs or from aircraft, or in some
specific instances by both means. The herbicidal solution often is
atomized by being forced under pressure through a flat fan nozzle,
a series of such nozzles being incorporated on a single spray boom.
Such nozzle dissemination techniques, as previously suggested,
commonly produce a wide range of droplet sizes. Droplet size
variation is undesirable, however, both from the standpoint of
dispersal and travel through the atmosphere and also effectiveness
in inhibiting the growth of unwanted plant life, or otherwise
controlling biological processes.
In relation to travel through the atmosphere, after the herbicidal
liquid leaves the nozzle, it has been found that the finer
droplets, such as those in the size range of less than 100 microns
in diameter, are often subject to objectionable drift. The drift
hazard from standard application techniques is well recognized for
the potentially damaging effect upon adjacent productive crops
which may be herbicide sensitive. Further, such drift, which
typically varies from 10 to 30 percent of the total spray volume
represents an economic waste and contributes to the total
atmospheric contamination level. Therefore, it is highly desirable
to be able to dispense a herbicide or other biological control
agent wherein the droplet size could be maintained at a selective
large diameter level to minimize drift hazards.
Moreover, and in relation to drop size upon the effectiveness of an
active control agent such as a herbicide, it should be noted that a
herbicide typically may be a water emulsion having a small
percentage by volume of active herbicidal agent such as, for
example, a low volatile 2,4-D ester and/or 2,4-D amine. As the
herbicide emulsion is dispensed, it collects in droplets upon the
weed leaf. The herbicide in the droplet is absorbed by the weed and
a water bridge appears to be essential for this uptake. The
evaporation rate of a small droplet may result in a water bridge of
such limited duration that insufficient active agent is taken up by
the leaf and therefore the undesirable plant life is not killed as
desired. In contrast, a large droplet may coalesce and run off or
fail initially to cling to an inclined leaf surface and therefore
tends to be wasteful. It would be highly desirable to be able to
dispense a liquid containing an active agent such as a herbicide
wherein the droplet size could be maintained within a selected size
band to maximize the desired effectiveness of the active agent.
OBJECTS AND SUMMARY OF THE INVENTION
Objects
It is therefore a general object of the invention to provide a
process and apparatus for dispensing a fluid which is designed to
obviate or minimize problems of the type previously described.
It is a particular object of the invention to provide a process and
apparatus for dispensing a fluid wherein the droplet size may be
predictably controlled within a desirable range of droplet
diameters.
It is another object of the invention to provide a process and
apparatus for jet stream atomizing a biological control agent such
as a herbicide in liquid form which will minimize the problems of
drift and atmospheric pollution and maximize the desired
effectiveness of the agent.
It is a further object of the invention to provide a process and
apparatus for jet stream atomizing a herbicide liquid of
substantially uniform droplet size with a high volumetric flow rate
so that a large crop area may be rapidly treated.
It is a still further object of the invention to provide an
improved process and apparatus for jet stream atomizing uniform
droplets of a vegetation control agent such as a liquid herbicidal
composition by imparting a disturbance to the atomized fluid by a
volumetric oscillation of a member in contact with the dispensed
fluid stream such that the rate of vibration of the member produces
a corresponding number of uniform droplets.
It is a related object of the invention to provide a process and
apparatus for jet stream atomizing uniform droplets of a liquid
herbicide in a cone array.
It is another related object of the invention to provide an
apparatus which may be readily adapted to existing nozzle
structures to enhance uniform droplet formation of fluid dispensed
from the nozzle.
Brief Summary
One preferred form of the invention intended to accomplish at least
some of the foregoing objects comprises a generally tubular jetting
nozzle having one end thereof sealed and the other end thereof
covered with an orifice plate. One or more orifices are fashioned
through the orifice plate in a generally central posture
therethrough for metering fluid to be dispensed into the
atmosphere. A passage is provided in a portion of the nozzle body
so that fluid may be delivered to the interior thereof from a
constant pressure source which may be selectively varied. A
volumetric displacement member is positioned so as to be in fluid
contact with the fluid exiting from the orifice. The displacement
member is connected to a conventional variable frequency AC power
source and is suitable for cyclic volumetric displacement in
response to excitation from the power source. The volumetric
displacement member transmits cyclic disturbances to the fluid as
it exits through the orifice and to the fluid jet column downstream
from the orifice. The fluid jet column is thereby dispersed into
droplets of uniform size.
A significant process aspect of the invention includes the steps of
delivering a fluid under pressure to a dispensing nozzle having an
orifice plate across one end thereof, jetting the fluid through the
orifice by pressure and transmitting a vibration to the fluid being
dispensed downstream of the orifice to induce the formation of
uniform fluid droplets in the liquid being dispensed.
THE DRAWINGS
Further objects and advantages of the invention will become
apparent from the following detailed description taken in
conjunction with the accompanying drawings, wherein:
FIG. 1 is a plan view of a vibratory atomizing device according to
a preferred embodiment of the invention;
FIG. 2 is a cross sectional view taken along section line 2--2 in
FIG. 1 disclosing more specifically the structure of a preferred
embodiment of the invention;
FIG. 3 is a plan view of an alternate preferred embodiment of the
invention;
FIG. 4 is a cross sectional view of the vibratory atomizing device
disclosed in FIG. 3 taken along section line 4--4;
FIG. 5 is a plan view of an improved orifice plate suitable for use
with a jet stream atomizing device;
FIG. 6 is a cross sectional view of the improved orifice plate
disclosed in FIG. 5 taken along section line 6--6; and
FIG. 7 is a schematic illustration of a jet stream atomizing device
of the invention utilizing the improved orifice plate, as seen in
FIG. 5 and 6.
DETAILED DESCRIPTION
Referring to the drawings and specifically to FIGS. 1 and 2
thereof, a vibratory atomizing device 10 according to a preferred
embodiment of the invention is shown.
The atomizing device 10 comprises a generally tubular nozzle body
12 having a suitable nozzle head such as an orifice plate 14
disposed across one end thereof. The orifice plate is provided with
an orifice 15 generally centrally thereof. The orifice plate 14 may
be removably attached to the nozzle body 12 by a conventional
threaded connector 16.
A side passageway 18 is fashioned through a lateral portion of the
nozzle body 12 to permit the delivery of a fluid 20 from a
pressurized source, not shown, into the internal cavity of the
nozzle body 12. The source of pressurized fluid may be of any
conventional type, such as for example a fluid tank with a
controllable air pressure head, suitable to deliver the fluid to
the nozzle at a selected constant pressure which may be varied from
a few pounds per square inch to several hundred pounds per square
inch, depending upon the viscosity of the fluid being dispensed and
the volume of fluid being dispensed. In any case, the pressure
should be sufficient to produce a desirable jet stream emanating
from the orifice. The fluid 20 may be selected from a variety of
substances such as, for example, water emulsions of pesticides,
herbicides or other plant or pest control agents, or solutions of
such agents in water or in some other appropriate liquid solvent
such as a non-phytotoxic mineral oil fraction.
The other end of the tubular nozzle body 12 is a sealingly covered
with a washer 22 having a central opening 24 therethrough. A
volumetric displacement shaft 26 formed from a material which will
exhibit magnetostrictive properties such as, for example, an iron
or nickle alloy, is provided to intimately engage the opening and
coaxially extend within the generally tubular nozzle body 12 to a
position adjacent the orifice 15 in the orifice plate 14.
The volumetric displacement shaft also extends exteriorly of the
nozzle body 12 and is surrounded by a sheath 28 carrying a
plurality of conductor windings 30. The sheath 28 is provided at
one end with a conventional threaded coupling flange 32 suitable to
removably connect the sheath to the nozzle body 12.
In order to axially retain the volumetric displacement shaft 26
within the nozzle body 12 and sheath 28, an O-ring 34 or other
suitable connector means, such as a bellows diaphragm washer, may
be connected to the shaft 26 and retained between the washer 22 and
a shoulder portion of the sheath 28.
The coil windings 30 are electrically connected to a conventional
variable frequency AC power source 36 which is suitable to produce
a varying current from 2,000 to 30,000 cycles per second or higher
in the windings depending upon the rate of displacement desired for
displacement shaft 26.
In operation the vibratory atomizing device 10, as shown in FIGS. 1
and 2, receives a liquid such as an aqueous emulsion of herbicide
into the interior of the dispensing nozzle 12 from a source which
is suitable to deliver the herbicide under a selected constant
pressure. This fluid then travels toward the orifice plate 14 and
is jetted through the orifice 15 in a uniform stream 38. The
frequency generator 36 is activated, which supplies an alternating
current to the windings 30. A magnetic flux will thus be
established in the shaft 26, which as previously mentioned, has
been selected to exhibit a high degree of magnetostrictive
displacement. More specifically, as the shaft 26 is cyclically
magnetized, it will expand and contract in response to the varying
current in the windings 30. This volumetric displacement of the
shaft 26 is imposed upon the liquid 20 particularly near the
jetting orifice 15 and also upon the liquid jet 38 downstream from
the orifice 15. The cyclic disturbances in the fluid column 38 will
result in regular nodes or anodes corresponding to the frequency of
volumetric displacement of the shaft 26 and thus produce droplets
39 downstream of the orifice 15 which will be uniform in size and
correspond in number to the frequency imposed upon the fluid column
38 by the volumetric displacement of shaft 26. The number of
droplets may be thus established by the rate of displacement of
shaft 26 and the size may be varied by varying the constant
pressure source acting to jet the fluid from the orifice 15.
While one skilled in the art will readily be able to practice the
invention according to the above disclosed process by selecting
operating parameters which would produce the desired results the
following example is illustrative of typical operating values.
EXAMPLE
A control agent as previously mentioned may be a water (typically
95 percent by volume) emulsion having a small percentage by volume
of an active agent. Therefore water at room temperature
(approximately 70.degree. F.) was delivered within a nozzle body as
illustrated in FIGS. 1 and 2 under a constant pressure of 30 pounds
per square inch gauge. The orifice size was 0.010 inches in
diameter and the dimension between the bottom of the
magnetostrictive shaft and the top of the orifice plate was 0.010
inches. The magneto-strictive device was vibrated at a frequency of
18,300 cycles per second and an essentially uniform droplet size of
0.015 inches in diameter was obtained.
An alternate embodiment of the vibratory atomizing device 40 may be
seen by referring to FIGS. 3 and 4.
A jet stream vibratory atomizing device 40 is provided with a
generally tubular nozzle body 42 having at one end thereof an
orifice plate 44 and at the other end thereof a cap 46. The orifice
plate 44 is removably attached to the nozzle body 42 by a
conventional coupler 60.
The nozzle body 42 is further provided with a passageway 50 in a
portion thereof for the delivery of fluid, such as for example,
herbicide into the interior of the nozzle body 42 for jetting
through an orifice 52 formed generally in a central portion of the
orifice plate 44.
The orifice plate 44 is composed of a piezoelectric crystal or in
some instances of a plurality of piezoelectric crystals and is
provided with electrical contact discs or washers 54 on each face
thereof. A pair of lead lines 56 connect the contact discs 54 to a
conventional variable frequency AC power source 58 which is
suitable to produce a varying voltage from 2,000 to 30,000 cycles
per second or greater.
In operation a herbicide is delivered under a selected pressure
into the interior of the nozzle body 42 and jetted through the
orifice 52 thus forming a generally uniform fluid column 62
downstream of the orifice. The orifice plate 44, as previously
mentioned, is composed of a piezoelectric crystal. This crystal may
be excited by imposing a variable potential across its face. The
crystal will thus volumetrically expand and contract. The expansion
and contraction will occur in a direct relationship to the
frequency of the potential applied and therefore the orifice 52
will expand and contract at the frequency of the applied voltage
from the variable frequency power source 58. The volumetric
displacement of the orifice will impose upon the fluid column 62 a
cyclic disturbance which will induce the formation of nodes and
anodes corresponding to the frequency of the disturbance in the
fluid column 62 and thus produce uniform droplets 64 downstream of
the orifice.
The number of droplets will be identical with the rate of
volumetric displacement and the volume of the droplets will be
controlled by the selection of the constant pressure under which
the fluid is delivered to the nozzle body as previously mentioned
in connection with the jet stream atomizing device shown in FIGS. 1
and 2.
It will be realized by those skilled in the art that the orifice or
orifices through the orifice plate presents a potential short
circuit avenue. If short circuiting becomes a problem the orifice
plate may be covered with a dielectric film or a herbicide may be
selected for its nonconductive properties.
While the above discussed embodiments of the invention disclosed in
FIGS. 1 and 2 and in FIGS. 3 and 4 disclose an orifice plate having
a single orifice fashioned through the center thereof, in those
instances where it is desired to dispense a high volume of fluid a
plurality of orifices 70 may be formed in an orifice plate as shown
in FIGS. 5 and 6.
Moreover where a plurality of orifices 70 are fashioned through an
orifice plate it may be desirable to dish the plate outwardly of
the nozzle body, as best illustrated in FIG. 6, by orifice plate
72. Such an outward bow of the orifice plate 72 will be suitable to
produce a conical spray pattern 74 as best seen in FIG. 7. In those
instances where a dish shaped orifice plate is utilized it may be
desirable to form the end of the magnetostrictive shaft 26 with a
compatible outwardly curved configuration so that the dis-tance
between the end of the shaft and the surface of the orifice plate
is substantially uniform.
As previously discussed, utilization of the magnetostrictive device
in conjunction with the disclosed nozzle body and orifice plate
produces a substantially uniform droplet size. It has been
discovered, however, that utilization of a magnetostrictive
volumetric displacement member, such as previously described,
upstream of a conventional nozzle head universally enhances the
droplet size control during jet stream atomization of a fluid. For
examples of typical nozzle head structures, such as a cone spray,
flat spray or flooding head, reference may be had to the
Transactions of the American Society of Agricultural Engineers,
Volume 9, No. 3, pages 303, 304, 305 and 308 (1966), the disclosure
of which is incorporated herein by reference as though set forth at
length.
It will be appreciated by those skilled in the art that the above
disclosure provides a process and apparatus for precision jet
stream atomizing a fluid into a uniform selected droplet size. In
addition, the above described process and apparatus may be utilized
for delivering a high volumetric flow of uniform droplets which may
be produced at a rate of 30,000 or greater droplets per second.
It will further be appreciated that the above described vibratory
atomizing devices will enhance the delivery or dispensing
capability of an agent such as a pesticide or herbicide by
minimizing the drift and atmospheric pollution while maximizing the
effectiveness of the application. Further, it will be recognized
that a degree of downstream pattern control may be provided by the
utilization of a dish shaped orifice.
Further, it will be appreciated that the magnetostrictive
volumetric displacement member may be readily mounted upstream of a
conventional nozzle head configuration of various designs to
enhance jet stream atomization of fluid through the nozzle head
into droplets of uniform size.
Although the invention is described with reference to preferred
embodiments, it will be appreciated by those skilled in the art
that additions, deletions, modifications, substitutions and other
changes, not specifically described and illustrated in these
embodiments, may be made which will fall within the purview of the
appended claims.
* * * * *