U.S. patent number 3,917,168 [Application Number 05/464,146] was granted by the patent office on 1975-11-04 for dispensing apparatus and method.
Invention is credited to William L. Tenney.
United States Patent |
3,917,168 |
Tenney |
November 4, 1975 |
Dispensing apparatus and method
Abstract
An ultra low volume (ULV) aerosol generator usable to dispense
fluid material in the form of relatively small droplets into the
atmosphere. The generator has a pump operable to deliver hot
compressed air to a dispensing nozzle. Fluid material under
pressure is supplied to the nozzle. A flow regulator controls the
rate of flow of fluid material to the nozzle and a flow meter plus
fluid material temperature sensing gauge is used to monitor the
rate of fluid flow. The hot air in the nozzle heats the fluid
material in the nozzle to decrease its viscosity and facilitate
atomization. Hot air under pressure and hot fluid material are
simultaneously discharged from the nozzle into the atmosphere. The
rapidly moving and expanding air atomizes the heated fluid material
into relatively small and generally uniform droplets.
Inventors: |
Tenney; William L. (Crystal
Bay, MN) |
Family
ID: |
23842750 |
Appl.
No.: |
05/464,146 |
Filed: |
April 25, 1974 |
Current U.S.
Class: |
239/13;
222/146.1; 239/130; 239/138; 239/424.5; 239/77; 239/132.1 |
Current CPC
Class: |
B05B
7/24 (20130101); B05B 7/162 (20130101); A01M
13/00 (20130101); A01M 7/0003 (20130101) |
Current International
Class: |
A01M
7/00 (20060101); A01M 13/00 (20060101); B05B
7/16 (20060101); B05B 7/24 (20060101); B05B
001/24 (); A01N 017/08 () |
Field of
Search: |
;239/8,13,71,73,74,77,128,130-132.1,135-139,172,176,290,296,299,314,418,423,424
;222/31,41,146H,146R,146HA ;43/125,132R,132A |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wood, Jr.; M. Henson
Assistant Examiner: Kashnikow; Andres
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. An apparatus for atomizing liquid material and dispensing the
atomized liquid material into the atmosphere comprising: pump means
operable to compress and heat air to a temperature of at least
250.degree. F., said pump means having an outlet means for carrying
heated air under pressure from the pump means, means for operating
the pump means, nozzle means including means of heat conducting
material for receiving the hot air under pressure and directing the
air into the atmosphere, means of heat conducting material having
first passage means for accommodating the hot air, connector means
coupling the nozzle means to the outlet means whereby the nozzle
means receives the hot air of at least 250.degree. F. under
pressure from the pump means and means for supplying liquid
material to the nozzle means, said means of heat conducting
material having second passage means accommodating the liquid
material, said second passage means being located adjacent the
first passage means whereby the liquid material is heated in the
nozzle means by the hot air passing through the first passage means
and mixed with the hot air whereby high velocity hot air atomizes
the liquid material as the hot air and heated liquid material are
discharged from the nozzle means into the atmosphere, said means
for supplying liquid material includes tank means for storing the
liquid material, first line means connecting the outlet means of
the pump means to the tank means whereby air under pressure is
supplied to the tank means to subject the liquid material in the
tank means to pressure, second line means separated from the
connector means and pump outlet means connecting the tank means
with the nozzle means to carry liquid material to the nozzle means
without substantially heating the liquid material, valve means in
the second line means to selectively stop or permit flow of liquid
material to the nozzle means, and means in the second line means to
regulate the rate of flow of liquid material to the nozzle means
when the valve means is open.
2. The apparatus of claim 1 wherein: the pump means is operable to
heat the air delivered to the nozzle means to a temperature in the
range of the boiling temperature of the liquid material.
3. The apparatus of claim 1 wherein: the pump means is operable to
heat the air delivered to the nozzle means to a temperature of at
least 300.degree. F.
4. The apparatus of claim 1 including: flow meter means in the
second line means to sense the flow rate of liquid material through
said second line means.
5. The apparatus of claim 4 including: means to sense the
temperature of the liquid material moving through the flow
meter.
6. The apparatus of claim 1 wherein: said valve means is mounted on
the nozzle means, and means operable to control the valve means to
selectively stop the flow of liquid material to the nozzle means
and permit the flow of liquid material to the nozzle means.
7. The apparatus of claim 6 wherein: the means to control the valve
means includes a solenoid and switch, said switch being located
remote from the solenoid.
8. The apparatus of claim 1 wherein: the pump means has a
reciprocating piston operable to compress and heat air.
9. The apparatus of claim 1 wherein: the nozzle means has a body
secured to the connector means, said body having first passage
means for carrying hot air from the connector means and a second
passage means for carrying liquid material, a head secured to the
body, said head having first passage means in communication with
the first passage means for the body and second passage means in
communication with the second passage means for the body whereby
hot air under pressure flows through said first passage means, said
hot air in the nozzle means operable to increase the temperature of
the liquid material, said first passage means and second passage
means of the head having outlets which provide for the mixing of
hot air and heated liquid material and directing the mixed hot air
and heated liquid material into the atmosphere whereby the heated
liquid material is atomized into relatively small droplets.
10. The apparatus of claim 9 wherein: said first passage means in
the body includes a plurality of passages located around the second
passage means of the body.
11. The apparatus of claim 9 wherein: the outlets include a liquid
outlet and an annular air outlet surrounding the liquid outlet.
12. The apparatus of claim 9 including: cap means attached to the
head, said cap means having at least one air outlet passage for
receiving hot air from the first passage means and directing said
hot air in an inward direction into the stream of liquid material
discharged from the nozzle means whereby the liquid material is
atomized by the high velocity expanding hot air.
13. The apparatus of claim 12 wherein: said cap means has an
annular air discharge outlet surrounding the liquid discharge
outlet.
14. An apparatus for atomizing liquid material and dispensing the
atomized liquid material into the atmosphere comprising: air
compressor means operable to increase the pressure of and heat air
to a temperature of at least 200.degree. F., means for operating
said compressor means, nozzle means for receiving the heated air
from the compressor and directing said air into the atmosphere,
said nozzle means including means of heat conducting material
having first passage means for carrying hot air, connector means
connecting the nozzle means with the compressor means so that the
nozzle means receives said heated air at a temperature of at least
about 200.degree. F. under pressure from the compressor means, and
means remote from the connector means for supplying liquid material
to the nozzle means, said means of heat conducting material of the
nozzle means having second passage means accommodating the liquid
material, said second passage means being located adjacent the
first passage means whereby the liquid material is heated in the
nozzle means by the hot air passing through the nozzle means and
mixed with the hot air whereby high velocity hot air atomizes the
liquid material as the hot air and heated liquid material are
discharged from the nozzle means into the atmosphere.
15. The apparatus of claim 14 wherein: the compressor means is
operable to heat the air delivered to the nozzle means to a
temperature in the range of the boiling temperature of the liquid
material.
16. The apparatus of claim 14 including: means to regulate the rate
of flow of liquid material to said nozzle means.
17. The apparatus of claim 14 including: valve means mounted on the
nozzle means operable to control the flow of liquid material to the
nozzle means, and means operable to control the valve means to
selectively stop flow of liquid material to the nozzle means and
permit flow of liquid material to the nozzle means.
18. The apparatus of claim 17 wherein: the means to control the
valve means includes a solenoid and switch, said switch being
located remote from the solenoid.
19. The apparatus of claim 14 including: flow meter means for
sensing the flow rate of liquid material from the means for
supplying liquid material under pressure to the nozzle means.
20. The apparatus of claim 19 including: means to sense the
temperature of the liquid moving through the meter means.
21. The apparatus of claim 14 wherein: the means of heat conducting
material includes a body secured to the connector means, said body
having first passage means for carrying hot air from the connector
means and a second passage means for carrying liquid material, a
head secured to the body, said head having a first passage means in
communication with the first passage means for the body and second
passage means in communication with the second passage means for
the body whereby hot air under pressure flows through said first
passage means, said hot air in the nozzle means operable to
increase the temperature of the liquid material, said first passage
means and second passage means of the head having outlets which
provide for the mixing of hot air and heated liquid material and
directing the mixed hot air and heated liquid material into the
atmosphere whereby the heated liquid material is atomized into
relatively small droplets.
22. The apparatus of claim 21 wherein: said first passage means in
the body includes a plurality of passages located around the second
passage means of the body.
23. The apparatus of claim 21 wherein: the outlets include a liquid
outlet and an annular air outlet surrounding the liquid outlet.
24. The apparatus of claim 14 wherein: the means for supplying
liquid material to the nozzle means includes suction means for
moving liquid material through the nozzle means.
25. The apparatus of claim 14 including: valve means operable to
selectively stop or permit the flow of liquid material to the
nozzle means.
26. A method of dispensing a liquid material into the atmosphere
with a nozzle comprising: compressing and heating air with pump
means, supplying the air compressed and heated by the pump means to
the nozzle at a temperature of at least 250.degree. F. to heat the
nozzle, supplying liquid material to the nozzle without
substantially heating the liquid material, heating said liquid
material in the nozzle by transferring heat energy from the heated
air to the liquid material, and simultaneously directing the heated
air and heated liquid material from the nozzle into the atmosphere
whereby high velocity heated air atomizes the heated liquid
material into relatively small droplets.
27. The method of claim 26 including: regulating the rate of flow
of liquid material to the nozzle.
28. The method of claim 26 including: sensing the flow rate of the
liquid material moving to the nozzle.
29. The method of claim 26 including: sensing the flow rate and
temperature of the liquid material moving to the nozzle.
30. The method of claim 26 wherein: the air supplied to the nozzle
is at a temperature of at least 300.degree. F.
31. The method of claim 26 wherein: the heated air is directed from
the nozzle in a cylindrical sleeve emanating from an annular air
outlet surrounding the liquid material outlet.
32. The method of claim 26 wherein: the air is heated to a
temperature to heat the nozzle to a temperature in the range of the
boiling temperature of the liquid material.
Description
BACKGROUND OF THE INVENTION
Dispensing apparatus and methods are widely used to distribute
materials in the form of liquid droplets into the atmosphere to
control insects, pests, bacteria, odors and other elements of the
environment. Fluid materials known as insecticides are dispensed
into the atmosphere to control insects, as mosquitoes and the
like.
The effective use of insecticides is required to achieve a good
mosquito control program. An effective toxicant includes an
effective control of the adult mosquito or larva, presents a low
hazard to man and animals and is versatile in formulations to
accommodate various methods of application. Malathion is widely
used in mosquito control operations today. Four main attributes
which have contributed to the use of Malathion for mosquito control
are a high toxicity to mosquitoes including chlorinated hydrocarbon
resistant strains and species that carry encephalitis or malaria; a
low toxicity to man and animals; lack of accumulation in soil and
water; and economy. Malathion, C.sub.10 H.sub.19 O.sub.6 PS.sub.2,
developed by American Cyanamid Company, was introduced to
commercial use in 1952. Methods of application of Malathion include
fogging, mist blowing, aerial spraying, dusting and ULV air and
ground application. Malathion is a clear brown to colorless liquid
having a specific gravity of 1.2315 at 25.degree.C. Its boiling
point is 156.degree.-157.degree.C. under 0.7mm pressure. Its
viscosity at 40.degree.C. is 17.57 centipoises and at 25.degree.C.
is 36.78 centipoises. The relatively high viscosity of Malathion at
normal ambient temperatures makes it difficult to atomize into
desirably small particles. However, at higher temperatures its
viscosity reduces rapidly and atomization is greatly
facilitated.
Thermal fogging machines, as shown by Tenney in U.S. Pat. No.
3,205,176, can be used to dispense Malathion as well as other
liquid insecticides. The thermal fogging machine produces a cloud
of fine droplets which can linger near the ground and drift through
the area inhabited by insects, as mosquitoes, flies and the like.
Thermal fogging machines normally use a carrier of a liquid
petroleum, as fuel oil, mixed with the insecticide. The mixture of
oil and insecticide is utilized by the thermal fogging machine to
dispense a cloud of fine insecticide and oil droplets into the
atmosphere.
One class of non-thermal dispensing machines is known as ultra low
volume (ULV) aerosol generators. These machines, in many cases, use
undiluted Malathion and other insecticides and have the alleged
advantages of increased effectiveness in killing insects,
eliminating or greatly reducing the base or carrier oil used in the
thermal generator, eliminating the sludge inhibitors as may be
needed for mixing the insecticide with the base oils, reducing the
weight carried by the vehicle used to transport the insecticide
formulation, reducing the insecticide and base oil cost and labor
requirements, and eliminating fogs that obscure visibility. This is
accomplished with a greatly reduced amount of base oil, thereby
enhancing the quality of the environment. An example of this type
of generator is shown by Waldron in U.S. Pat. Nos. 3,633,825 and
3,702,306. A ULV cold aerosol generator using Malathion, according
to the manufacturer of Malathion, should produce spray droplets in
the range of 5-15 microns and not larger than 23-27 microns in
size. Larger droplets may impinge on objects in their pathway and
may permanently damage automobile paint.
SUMMARY OF INVENTION
The invention is directed to a method and apparatus for atomizing a
liquid material and dispensing the atomized liquid material into
the atmosphere for the control of insects, pests odors and the
like. More particularly, the invention is directed to a method and
apparatus for dispensing liquid insecticide, as Malathion, Dibrom,
Pyrethum, and the like, into the atmosphere for controlling
insects, as mosquitoes, flies and the like. The apparatus has pump
means operable to compress and heat air. The pump means has an
outlet for carrying the heated air under pressure to a nozzle
means. The hot air from the pump means heats the nozzle means. The
nozzle means has air discharge outlets which direct the heated
compressed air into the atmosphere. The liquid insecticide is
supplied to the nozzle means by pressure or suction forces. The
insecticide flows through the nozzle means and is heated to a
temperature approaching that of the hot air flowing through the
nozzle means and is discharged through a liquid outlet
simultaneously with the discharge of air. The expanding and rapidly
moving air and liquid insecticide under pressure coact with each
other to create mechanisms, including shearing and expansion
forces, which break up the liquid insecticide into relatively small
and generally uniform droplets. The heating of the liquid
insecticide in the nozzle means produces a decrease in the
viscosity of the liquid insecticide, making it much easier to break
up into relatively uniform droplets in the desired particle size
range. The flow of liquid insecticide to the nozzle means may be
controlled with a flow regulator or by the construction of the
nozzle means. The relatively cold liquid insecticide flows through
the regulator, providing control of relatively low volumes of
liquid insecticide to the nozzle.
The method of dispensing the liquid material into the atmosphere
with a nozzle means includes the step of compressing and heating
the air with a pump. The compressed and heated air is supplied to
the nozzle means to heat the nozzle. Liquid material is supplied to
the nozzle means and flows through the nozzle means so that the
liquid material is heated in the nozzle with the hot air supplied
to the nozzle. The heated air and the heated liquid are
simultaneously discharged from the nozzle into the atmosphere. The
high velocity expanding air and liquid react with each other to
break up the liquid material into relatively small particles in a
dispersion pattern away and downstream of the nozzle means. The
rate of flow of liquid material to the nozzle means may be
regulated and sensed. The temperature of the liquid material at the
flow rate sensing instrument may also be sensed.
An object of the invention is to provide an Ultra Low Volume
aerosol generator which uses hot air in the nozzle to heat liquid,
as liquid insecticide or other insecticide formulations, to a
temperature which does not significantly alter the insecticide
properties of the liquid but sufficiently reduces the viscosity so
that the liquid will break up more easily into the desired
relatively small and uniform droplets. Another object of the
invention is to provide an apparatus and method for dispensing a
liquid material which reduces the amount of liquid formulation
released into the environment, yet has increased insect kill
effectiveness. A further object of the invention is to provide an
air and liquid dispensing nozzle and apparatus of simple
construction which functions to heat the air and then transfer heat
from the air to the liquid and thus discharge air and liquid into
the atmosphere in a desirably small and uniform droplet size range.
Yet another object of the invention is to provide a very simple and
low cost apparatus and method for dispensing liquid materials in
the desired droplet size range into the atmosphere which is rugged
and reliable in construction and operation.
In the drawings:
FIG. 1 is a side elevational view of the ULV aerosol generator of
the invention mounted on a pickup truck;
FIG. 2 is a side elevational view of the aerosol dispensing nozzle
and adjacent apparatus diagrammatically associated with the air
compressor;
FIG. 3 is a perspective view of the remote control and instrument
panel in the line between the liquid tank and the dispensing nozzle
of the ULV aerosol generator of FIG. 1;
FIG. 4 is an enlarged sectional view of the solenoid valve
connected to the dispensing nozzle;
FIG. 5 is an enlarged longitudinal setional view taken along the
line 5--5 of FIG. 2;
FIG. 6 is a sectional view taken along the line 6--6 of FIG. 5;
and
FIG. 7 is a sectional view taken along the line 7--7 of FIG. 5.
DESCRIPTION OF PREFERRED EMBODIMENT
Referring to FIG. 1, there is shown the ultra low volume (ULV)
aerosol generator or dispensing apparatus of the invention
indicated generally at 10 mounted on the rear portion of the body
11 of a pickup truck 12. Pickup truck 12 is illustrated as one type
of vehicle used to transport the generator 10. Other types of
vehicles, as trailers, hand carts and wheeled frames, can be used
to transport the generator.
The ULV aerosol generator 10 has an air compressor or pump 13
driven by a motor 14. The motor 14 is preferably an internal
combustion engine, such as a four cycle, single cylinder engine.
Other types of engines, including electric motors, can be used to
drive the air compressor. A belt and pulley drive system 16
connects the output of the motor to the air compressor 13.
Alternatively, a direct drive between the motor and air compressor
can be used. A fuel tank 17 located adjacent the motor 14 is
connected with a suitable fuel line to the carburetor of the motor
in the conventional manner.
The air compressor 13 has an outlet pipe 18 connected to the outlet
19 of the compressor. As shown diagrammatically in FIG. 2, the air
compressor 13 has a reciprocating piston and suitable valving (not
shown) operable to force air through the outlet port 19 into the
outlet pipe 18. The air discharged from compressor 13 is at an
elevated temperature, for example, 300.degree. F. Other
temperatures of the air in this range can be attained by the
compressor. Compressor 13 is an air pump operable to discharge hot
air under pressure in a range between approximately 30 and 150 psi.
The air pump may be of piston type construction. Other suitable
types of air pumps may also be used to heat and pressurize the
air.
Outlet pipe 18 is connected to an air filter 21. The casing of air
filter 21 may be of a size to assist in damping out air pressure
fluctuations generated by air compressor 13. In some dispensing
apparatus air filter 21 can be eliminated. A discharge nozzle 22 is
mounted on the filter 21 with a connector indicated generally at
23. Connector 23 can be a ball joint or other suitable universal
joint type structure. Nozzle 22 projects rearwardly and upwardly at
an angle of about 45.degree. to introduce the aerosol upwardly and
rearwardly into the atmosphere behind the truck. The direction of
the nozzle outlet may be adjusted by changing the position of the
ball joint connector 23. A heat insulation material may be applied
to pipe 18, filter 21, connector 23, nozzle 22 and associated
structures to minimize heat losses. Nozzle 22 is an external mixing
nozzle having a generally flat elliptical spray pattern. Internal
mixing nozzles or other types of nozzles may also be used with the
ULV aerosol generator 10. The connector 23 has an elbow 26 carrying
a pair of interconnected members 27 and 28 forming a ball type
universal joint. The member 28 retains a movable member 30 secured
to an angle tube or pipe 29 and is movable so that the horizontal
and/or vertical angle or discharge direction of the nozzle 22 can
be changed. The pipe 29 has an outer threaded end 31 threaded into
the nozzle 22. An air line 32 is connected to the top of filter 21
with a connector 33. Air line 32 is connected to the top of a
formulation tank 34. A pressure regulator 32A is located in line 32
to limit the pressure of air delivered to tank 34. A pressure gauge
and pressure release valve can be included in line 32 between
regulator 32A and tank 34. When a suction type nozzle is used, the
line 32 may be dispensed with. As shown in FIG. 1, formulation tank
34 is located adjacent the motor and is used to store the fluid, as
liquid insecticide. Tank 34 is fluidly connected with a line or
hose 36 to the remote control and instrument panel 38. Connector
36A, having a removable line filter is mounted on top of tank 34.
Line 36 is attached to the outlet of connector 36A and a drop pipe
36B extended toward the bottom of tank 34 is attached to the inlet
of connector 36A. Drop pipe 36B, connector 36A and hose 36 carry
the fluid to a remote control and instrument panel 38. A second or
return line 37 carries the fluid from remote control and instrument
panel 38 to the nozzle 22.
As shown in FIG. 3, the remote control and instrument panel 38 has
a flow meter 39 comprising a generally upright tube 41 having a
passage containing a ball 42. The tube 41 is calibrated with scale
43 to provide a visual indication of the position of the ball 42 in
the tube 41. A control valve 44 is located adjacent the upper end
of the tube 41 to regulate the flow of liquid through the tube. The
passage in tube 41 increases in diameter from the bottom so that
the higher the location of ball 42 in the passage, the greater the
indicated flow of liquid through the passage. Remote control and
instrument panel 38 also contains a fluid temperature gauge 46
which indicates the temperature of the fluid at the flow meter 39,
and an air pressure gauge 47 indicating air pressure delivered to
nozzle 22. An air pressure line (not shown) connects gauge 46 with
the air outlet of filter 21. Located below gauge 47 is an on/off
switch 48 for controlling the flow of liquid to the nozzle. The
flow meter 39, gauges 46 and 47 and on/off switch 48 are all
mounted on a frame assembly 49. As shown in FIG. 1, the remote
control and instrument panel 38 is located in the cab of the pickup
truck 12 where it is readily accessible to the operator of the
truck.
Referring to FIG. 4, there is shown a solenoid valve 51 operable to
control the flow of liquid to the nozzle 22. Valve 51 has a body 52
having a passage 53 for the flow of liquid through the body 52. A
plunger 54 is operable to close passage 53 thereby preventing the
flow of liquid through the passage. Spring 56, engageable with a
fixed stop 57 and plunger 54, operates to bias plunger 54 to a
closed position. The fluid under pressure is applied across the
spring end of plunger 54 to aid the spring 56 in holding the
plunger 54 in its closed position, preventing the flow of liquid
through the valve. An elongated cylindrical coil 58 surrounds
plunger 54 and stop 57. Leads 59 are connected to the coil 58.
Leads 59 are connected to the on/off switch 48 on the frame
assembly 49 and a power source, such as the battery of the truck or
the electrical system of the compressor motor, by suitable wiring
(not shown). When switch 48 is in the "on" position, coil 58 is
energized. This moves plunger 54 to the open position, allowing the
flow of liquid through passage 53 and into nozzle 22. The solenoid
51 is mounted on nozzle 22 with a short nipple 61, shown in FIG.
2.
Referring to FIGS. 5, 6 and 7, nozzle 22 has a body 62 of heat
conductive material, as aluminum. One end of body 62 has a threaded
air inlet opening 63 accommodating threaded end 31 of the angle
pipe 29 so that the nozzle 22 is mounted on pipe 29. The outlet end
of body 62 has an annular recess 64. A plurality of longitudinal
passages 66 connect the inlet 63 with the annular recess 64. The
end of the body 62 adjacent the annular recess 64 has a continuous
flat face 67.
As shown in FIGS. 5 and 6, body 62 has a fluid inlet port 69 for
receiving the threaded nipple 61. The port 69 extends to the center
of body 62 and is in communication with a longitudinal central
passage 71. Passage 71 is open to face 67 of the end of body 62.
The annular recess 64 surrounds and is concentric with the passage
71.
Mounted on the outer end of body 62 is a head or nozzle unit 72
operable to concurrently discharge heated air and heated liquid
under pressure into the atmosphere. The air and liquid are mixed
with the liquid being broken down into desirably small particles.
Head 72 has a threaded tubular member or projection 73 that is
threaded into the passage 71. The base of head 72 has a flat end 74
facing the flat surface 67 of the body 62. An annular washer or
seal 76 is located between surfaces 67 and 74 so that head 72 is
mounted in a sealing relation on body 62. The base of head 72 has
an annular recess 77 facing the annular recess 64 in the body. The
washer 76 has a plurality of holes 76A to provide air communication
between the recesses 64 and 77. Head 72 has a plurality of passages
78 that extend through the head. The passages 78 are open to the
annular groove 77 and the opposite end of the head. Located
centrally of the passages 78 is a longitudinal center passage 79 in
communication with passage 71. The upper end of head 72 has an
outwardly directed projection or nipple 81. A longitudinal passage
82 extends through the nipple 81. The passage 82 is smaller than
and open to passage 79 and provides an outlet for the liquid and
provides the liquid with velocity energy.
A cap 83 is mounted on the end of the head 72. The cap 83 has an
outwardly directed annular flange 84. A nut or ring 86 threaded on
the head 72 engages the flange 84 to hold the flange in engagement
with head 72. The cap 83 has an internal recess 87 providing a
chamber for the air discharged from the passages 78. An opening or
air outlet 88 is open to recess 87 and surrounds the outer end of
nipple 81 providing an annular air outlet around the nipple 81.
This forms an annular sheath of air concentric about the stream of
fluid discharged from the fluid outlet 82. Cap 83 has diametrically
opposite ears 89 and 91 which project in a downstream direction.
Ears 89 and 91 have passages 92 and 93 in communication with the
recess 87. The passages 92 and 93 have inwardly directed outlet
openings which direct additional air jets into the stream of liquid
and air moving from the outlets 82 and 88.
The stream of liquid and air discharged from the outlets 82, 88, 92
and 93 is indicated at 94. This stream moves outwardly in a
longitudinal direction with the liquid being progressively broken
up into relatively small droplets by the rapidly moving and
expanding heated air. The moving air has a shearing effect on the
liquid which atomizes the liquid into small droplets. The
cylindrical sheath of air discharged from outlet 88 initially
surrounds the liquid stream. Air jets 97 and 98 from the passages
92 and 93 broaden the spray pattern, provide for additional mixing
of the air with the liquid, and aid in atomizing the liquid. The
nozzle 22 functions to heat the liquid by transferring heat energy
from the hot air supplied to it to the liquid also supplied to it.
Heated liquid and hot air under pressure are simultaneously
discharged to atomize or break up the liquid into relatively
uniform and small droplets and to disperse these droplets into the
atmosphere in a generally elliptical spray pattern. The heating of
the liquid decreases its viscosity. The low viscosity of the liquid
influences the droplet size. The liquid breakup is caused by a
number of mechanisms including the collapse of unstable liquid
sheets, the drop in pressure of the expanding air, and the shearing
action of the moving and expanding air. With higher liquid
viscosity, larger forces are necessary to atomize and break up the
liquid. Surface tension of the liquid must also be overcome in
creating droplets.
When Malathion is the liquid insecticide supplied to the nozzle 22,
the hot air in nozzle 22 may elevate the temperature of the
Malathion to about 200.degree.F. or more, thereby markedly
decreasing its viscosity. The simultaneous dispensing of hot air
under pressure and hot Malathion into the atmosphere produces
relatively uniform particles in the range of 5-15 microns. A
similar action also occurs with some other fluids. Other types of
materials can be dispensed with the apparatus to control insects,
odors and pests. The apparatus 10 can also be used to dispense
materials such as tear gas, sanitizing agents, particles for snow
precipitation, and the like.
In terms of method, the aerosol generator 10 is operable to
dispense a material, as a liquid insecticide formulation, into the
atmosphere in desirably small and uniform particles or droplets.
The air is initially compressed and heated with the pumping action
of the compressor 13 to a temperature of at least 200.degree. F.
The motor 14 is operable to drive compressor 13. The compressed and
heated air is carried to the dispensing nozzle 22 with a minimum of
heat loss. The heated air heats nozzle 22 so that the liquids that
are moved through the nozzle are heated in the nozzle. It is
desirable to deliver the heated air to the nozzle at a temperature
of at least 200.degree. F. The material is supplied to nozzle 22
under pressure. For example, when Malathion is used, it may be
supplied to the nozzle at the rate of 3-4 fluid ounces per minute.
The rate of flow of liquid through the flow meter is regulated in
accordance with the truck speed. For example, when Malathion is
used, a truck speed of 5 miles per hour may correspond to a flow
rate of 1-1.5 fluid ounces per minute. Likewise, a truck speed of
10 miles per hour may correspond to a flow rate of 2-3 fluid ounces
per minute. The flow rate is constantly monitored by the operator
to maintain uniform control of the discharge rate.
The material is stored in tank 34. Air from the compressor is
supplied to the tank to place the material under pressure. The
material moves from the tank through the remote control and
instrument panel 38 and to the control solenoid valve 51 mounted on
nozzle 22. Remote control and instrument panel 38 has valve 44
operable to adjust the flow of liquid to nozzle 22. With the
solenoid switch 48 in the "on" position, the coil 58 is energized,
moving plunger 54 to the open position, thereby permitting the flow
of material through the passage 53 of the solenoid valve 51.
As shown in FIG. 5, the material flows into the longitudinal
passage 71 open to passage 79. The material, being under pressure,
is forced through the exit opening 82 into a longitudinal stream of
material 94 into the atmosphere. The hot compressed air is
delivered to the inlet 63 of the body 62. The air flows through
passages 66 into the annular recesses 64 and 77. The air then flows
through the passages 78 in head 72 into the annular recess 87. In
the annular recess 87 the air is divided into three parts. One part
of the air flows through the annular outlet 88, forming the jet
sheath of air about the material stream moving from liquid outlet
82. The other two parts of the air flow through the passages 92 and
93 and are directed inwardly as air jets into the mixture of air
and material. The material from the time it enters the body 62
until it is discharged into the atmosphere is surrounded with
passages containing the heated air. This increases the temperature
of the material within the nozzle to a point below the vaporization
temperature of the material. For example, the temperature of the
material in the nozzle may be between 200.degree. F. and
350.degree. F. (93.degree.-176.degree. C.) or more. This condition
also exists a short distance outwardly into the atmosphere as the
air jets surround the liquid stream 94 and progressively atomize or
break up the liquid into relatively small droplets. The moving and
expanding air jet produces an abrupt drop in pressure at the
discharge area of the liquid. This movement and pressure drop
results in forces that atomize the hot liquid into relatively small
particles or droplets. The majority of the droplets are preferably
in a size range of 5-15 microns when Malathion is used.
The temperature of the material in the nozzle may be above the
vaporization point of the material. Also, the material can be
supplied by suction forces from the nozzle in lieu of air pressure
in tank 34.
The heating of the liquid material in the nozzle 22 according to
the invention greatly facilitates the breakup and atomization
thereof into desirably small particle size ranges. At the same
time, the elevated temperature aids in producing more uniform
particle sizes. The heating of the liquid material in the nozzle
also permits the use of a less costly and less complex nozzle. This
heating further reduces the amount of air required to achieve the
desired degree of atomization of the liquid material. Accordingly,
a small capacity, lighter and less costly air compressor and drive
motor for the compressor are needed.
While the forms of the dispensing apparatus and method herein
described constitute preferred embodiments of the invention, it is
to be understood that the invention is not limited to these precise
forms of apparatus and that changes may be made therein without
departing from the scope of the invention which is defined in the
appended claims.
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