U.S. patent application number 09/733371 was filed with the patent office on 2001-05-03 for method and apparatus for thermally killing weeds.
Invention is credited to Prull, Gregory G..
Application Number | 20010000554 09/733371 |
Document ID | / |
Family ID | 22934040 |
Filed Date | 2001-05-03 |
United States Patent
Application |
20010000554 |
Kind Code |
A1 |
Prull, Gregory G. |
May 3, 2001 |
Method and apparatus for thermally killing weeds
Abstract
A method and apparatus for thermally killing weeds and other
unwanted vegetation from areas where their presence is undesirable.
The method and apparatus are especially useful for killing weeds
located adjacent auto or rail roadways or airport runways. The
method of killing weeds involves first spraying the weeds with an
amount of water sufficient to cover a substantial portion of the
exposed outer parts of the weeds, and then subjecting the water
covered weeds to an elevated temperature sufficient for the time of
exposure to kill them. The apparatus for thermally killing weeds by
this method includes a water sprayer unit and a heater enclosure or
box, the water sprayer unit being located in front of the heater
box. The heater box has burners located at the forward end thereof
that impact a heatable element capable of generating infra-red
radiation. A porous apron extends between the bottom of the heater
box and the ground to allow exhausting of combustion products and
water vapor.
Inventors: |
Prull, Gregory G.; (Veneta,
OR) |
Correspondence
Address: |
Robert E. Howard
P. O. Box 10345
Eugene
OR
97440
US
|
Family ID: |
22934040 |
Appl. No.: |
09/733371 |
Filed: |
December 8, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09733371 |
Dec 8, 2000 |
|
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09247207 |
Feb 9, 1999 |
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Current U.S.
Class: |
47/1.44 |
Current CPC
Class: |
A01M 21/04 20130101 |
Class at
Publication: |
47/1.44 |
International
Class: |
A01M 015/00 |
Claims
The invention claimed is:
1. A method for killing weeds comprising first spraying the weeds
with water, and next, non-simultaneously with said spraying,
subjecting the wet weeds to an elevated temperature for a period of
time sufficient to kill at least the exposed portions of said
weeds.
2. The method of claim 1 wherein said water sprayed onto said weeds
is at ambient temperature.
3. The method of claim 1 wherein said water sprayed onto said weeds
is at a temperature above ambient temperature.
4. The method of claim 1 wherein the weeds sprayed with water are
subjected to infrared radiation.
5. A method for killing weeds comprising first spraying the weeds
with water, and next, non-simultaneously with said spraying,
subjecting the wet weeds to an elevated temperature from a source
of infrared radiation for a period of time sufficient to kill at
least the exposed portions of said weeds.
6. An apparatus for thermally killing weeds comprising: a heater
enclosure having means for generating infrared radiation, said
enclosure having at least one opening in the bottom thereof for
communicating said infrared radiation with said weeds; and spray
means for spraying water onto said weeds, said sprayer means being
located forward of said heater enclosure a distance adapted to
provide that in operation said weeds are first subjected to said
water from said spray means, and next, non-simultaneously with said
spraying, subjected to said infrared radiation from said heater
enclosure.
7. The apparatus of claim 6 wherein said means for generating
infrared radiation includes at least one heat absorbing element
capable of generating infrared radiation upon heating, and heating
means for heating said element.
8. The apparatus of claim 7 wherein said heating means is comprised
of at least one burner adapted to combust liquid fuel to produce a
flame and to direct said flame into contact with said heat
absorbing element.
9. The apparatus of claim 8 wherein said heating means includes
means for preheating the liquid fuel prior to combustion in said
burner.
10. The apparatus of claim 8 including means for supplying air to
the liquid fuel prior to combustion in said burner.
11. An apparatus for thermally killing weeds comprising: a heater
enclosure having a top, a pair of substantially parallel side walls
and a first end wall extending between said side walls adjacent the
front of said enclosure and a second end wall extending between
said side walls adjacent the rear of said enclosure, said end walls
being substantially parallel to each other, the bottom of said
enclosure being open; a layer of insulation adjacent the top of
said heater enclosure; an infrared heating element having an upper
surface in contact with said layer of insulation at the top of said
heater enclosure and a lower surface facing the open bottom of said
enclosure; a heater manifold extending between said side walls and
closely adjacent said first end wall, a manifold pipe located
within said heater manifold, said manifold pipe having a first end
communicating with a source of flammable fuel, said manifold pipe
communicating with a plurality of burners along at least a portion
of its length, said burners having an outlet communicating with the
interior of said heater enclosure and adapted to direct their
flames into contact with said lower surface of said infrared
heating element; and a sprayer means for spraying water, said
sprayer means being located forward of said first end wall.
12. The apparatus of claim 11 wherein said infrared heating element
is comprised of corrugated metal having a plurality of ridges
extending downwardly toward the bottom of said enclosure.
13. The apparatus of claim 12 wherein said ridges are substantially
parallel to said end walls.
14. The apparatus of claim 12 wherein said ridges are substantially
parallel to said side walls.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
1. This is a continuation-in-part of application No. 09/247,207
filed Feb. 9, 1999.
BACKGROUND OF THE INVENTION
2. This invention relates to a method and an apparatus for
thermally killing weeds.
3. The use of chemical herbicides to kill weeds has come under
increasing attack as being environmentally unfriendly.
4. A number of alternative ways of killing weeds have been
suggested.
5. Thermal killing of weeds has achieved some measure of success as
an alternative to the use of herbicides. Some such devices burn
propane or other gaseous or liquid hydrocarbons to produce flames
or hot air aimed directly at the weeds. See, for example, the
devices described in U.S. Pat. Nos. 5,020,510 and 5,189,832. One of
the problems associated with this approach is setting fire to the
weeds, which generates air pollution and, possibly, wild fires.
6. It has also been suggested to use hot foams to kill Tweeds. See,
for example, U.S. Pat. No. 5,575,111.
7. It has been further suggested to spray hot water on weeds
followed by compressing the sprayed weeds or applying a foam
blanket to the sprayed weeds, the purpose of both approaches being
to hold the hot water against the plants for an extended period of
time. See, for example, U.S. Pat. Nos. 5,430,970 and 5,433,758.
8. It is an object of this invention to provide a method and
apparatus for thermally killing weeds that is effective,
economical, and minimizes the potential for inadvertently causing
fires.
SUMMARY OF THE INVENTION
9. The invention is a method and apparatus for thermally killing
weeds, grasses, or other unwanted vegetation adjacent auto or rail
roadways, airport runways, or any area where it is desired to
remove such unwanted vegetation.
10. The method of this invention for thermally killing weeds
involves first applying water at ambient temperature onto the weeds
targeted to be eliminated and subsequently heating the water and
the weeds to a temperature sufficient to cause bursting of cell
walls and denaturing of plant proteins which results in the death
of the exposed tops of the weeds.
11. The apparatus for thermally killing weeds comprises a water
spray unit and an associated heater enclosure or box located in
trailing relationship to the heater. The heater box has a top or
roof, side walls, and end walls. The bottom of the heater box is
open to the atmosphere. The heater box has an infrared heat
generating element located on the underside of the roof. The
infrared heat generating element gray be corrugated or otherwise
shaped to provide maximum exposure of the weeds to infrared
heating. The open bottom of the heater box is, in operation,
located close to ground level, and has a porous apron extending
from the bottom of the heater box into contact with the ground.
BRIEF DESCRIPTION OF THE DRAWINGS
12. FIG. 1 is a side view of a first embodiment of the apparatus of
the present invention;
13. FIG. 2 is a partial side view, in section, of the heater box of
the first embodiment of the apparatus of the present invention;
14. FIG. 3 is a bottom view of the first embodiment of the
apparatus of the present invention;
15. FIG. 4 is a bottom view of the second embodiment of the
apparatus of the present invention;
16. FIG. 5 is a lateral cross-sectional view taken along line 5--5
of FIG. 4 of the heater box of the second embodiment of the
apparatus of the present invention; and
17. FIG. 6 is a longitudinal cross-sectional view of the heater box
of the second embodiment of the apparatus of the present
invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
18. The thermal weed killer apparatus 10 of the invention is mobile
and can be moved over the ground in an area where it is desired to
kill unwanted vegetation. Such movement can be effected in a number
of ways. A preferred way is to pivotally attach apparatus 10 to one
end of a boom 12, the other end of boom 12 being connected to a
motorized vehicle (not shown). Other means of attachment to a
motorized vehicle can be used. Also, apparatus 10 could be
configured for either manual or self-contained motorized movement,
or towing behind a motorized vehicle.
19. A metal heater enclosure or box 20 has an open bottom 22 which,
in operation, is located closely adjacent the ground, as seen in
FIG. 1. A plurality of chains 23 extend between the bottom 22 of
heater box 20 and the ground to provide a porous apron. Other
flexible means providing such a porous apron may be used instead of
chains.
20. Heater box 20 is comprised of a metal top 24, a pair of
parallel metal side walls 26 and a pair of parallel metal end walls
28. A layer of insulation 30 is located between top 24 and infrared
element 32 located below and parallel to top 24.
21. Infrared element 32 is made of metal or other heat absorbing
material capable of generating infrared radiation when heated, and
is preferably corrugated with a plurality of ridges 34 extending
downwardly and parallel to end walls 28, as shown.
22. A heater manifold enclosure 40 extends between side walls 26
closely adjacent the front end wall 28. Located inside manifold
enclosure 40 is a U-shaped manifold pipe 42 communicating with a
plurality of burners 44 extending outwardly from manifold pipe 42
and manifold enclosure 40 toward rear end wall 28. Manifold pipe 42
communicates with flexible or rigid conduit 46 via union 47, and
conduit 46 communicates manifold pipe 42 with a supply tank of
flammable fuel (not shown), such as propane. Such a propane tank
may be mounted on the heater box 20 of apparatus 10, but it can be
carried by the motorized vehicle to which apparatus 10 is attached
or in a separate trailer.
23. In order to accomplish efficient combustion, it is important
that the liquid fuel be preheated sufficiently to vaporize it prior
to combustion. Such preheating can be accomplished in a number of
ways. One way is to configure manifold pipe 42 in a U-shape, as
illustrated. Such a U-shape configuration heats up the liquid fuel
entering manifold pipe 42 by having the initial leg thereof being
in close proximity to the final leg thereof, the final leg being
heated by burners 44.
24. Although manifold pipe 42 is illustrated as being U-shaped to
effect preheating of the liquid fuel, manifold pipe 42 may be
straight or have other shapes with preheating being accomplished in
other ways, such as by passing conduit 46 through the space between
infrared element 32 and the top 24 of heater box 20, or having a
separate heater for preheating the liquid fuel.
25. An air blower 48 supplies air via rigid or flexible conduit 49
to the fuel entering manifold pipe 42 at an appropriate location,
such as at union 47.
26. A water sprayer unit 50 is attached to the front end wall 28 of
heater box 20 by a plurality of support arms 52. Sprayer unit 50
has a plurality of holes and/or nozzles 54 located thereon. A
flexible or rigid conduit 56 communicates sprayer unit 50 with a
tank of water (not shown), which can be mounted on the heater box
20 of apparatus 10, but it can also be carried by the motorized
vehicle to which apparatus 10 is attached.
27. The water supplied to sprayer 50 is preferably maintained at
ambient temperature to reduce costs and the complexity of the
thermal weed killer apparatus, but the water may be preheated to
facilitate operation of apparatus 10 at a higher rate of speed by
thereby requiring less residence time of heater box 20 over the
wetted weeds.
28. Although the water sprayer unit 50 is preferably attached to
heater box 20 of apparatus 10, it could be mounted on the vehicle
to which apparatus 10 is attached or could be attached to a
separate vehicle.
29. It is desirable to locate a secondary spray system on the
apparatus to allow any weed fires that might be started to be
extinguished. To this end, secondary water spray unit 60 may be
attached to heater box 20 by means of a plurality of support arms
62. A rigid or flexible water supply conduit 64 communicates with
the water supply tank of apparatus 10.
30. In operation, apparatus 10 is moved, via boom arm 12 mounted on
a motorized vehicle, over a highway shoulder, railroad ballast
area, or other area where it is desired to kill weeds. Apparatus 10
is moved in the direction indicated by the arrows in FIGS. 1-3.
31. Water is fed to sprayer 50 and exits holes/nozzles 54 to douse
weeds passing beneath sprayer 50.
32. Propane or other flammable fuel is fed from a supply tank to
manifold pipe 42 via conduit 46. Air is supplied from blower 48 via
conduit 49. The fuel and air mixture is lit as it exits burners 44.
The heat generated by burners 44 heats infrared element 32 to
produce infra-red radiation within heater box 20, which is directed
downwardly through open bottom 22 and onto the moisturized weeds
passing beneath heater box 20. The water on the weeds enhances
conduction of heat to the plant's exposed surfaces and helps retain
heat to thereby lengthen the time of exposure of the weeds to
elevated temperatures. The temperature generated by heater 20 is
sufficient to vaporize at least some of the sprayed-on water from
the weeds. The sprayed-on water significantly assists in subjecting
the weeds to a killing temperature.
33. Although infrared radiation generated by infrared heating
element 32 is the primary source of heat applied to the target
weeds, there is some direct contact of taller weeds with the flames
issuing from burners 44. In addition, some turbulent hot air is
generated by the burners 44 which can also contact target weeds and
assist in vaporizing water from the leaf surfaces of these
previously sprayed weeds.
34. Apparatus 10 is moved over the weeds at a speed to vaporize all
or substantially all of the thin film of water coating the weeds
but not to such conditions as would cause the weeds to combust.
However, if the apparatus is being operated in weather or other
conditions where it is difficult to prevent the weeds from catching
on fire, secondary sprayer unit 60 may be operated to prevent such
fires.
35. The porous apron formed by chains 23 or other porous curtain
material allows water vapor and combustion products to escape to
the atmosphere. The mechanical action of the porous apron also
helps extinguish any flames should they occur.
36. A second embodiment of the heater enclosure or box is shown in
FIGS. 4-6. Parts common to the weed killer apparatus 10 of the
invention described above relative to the first embodiment have the
same reference number. Parts of the second embodiment that are
similar in function to those parts of the first embodiment have the
same reference number but increased by 100.
37. Heater enclosure or box 120 is open at the bottom and includes
a sloping metal top 124, a pair of parallel metal side walls 126, a
front metal end wall 128 and a parallel rear metal end wall 128'.
The metal top 124 of heater box 120 slopes downwardly from adjacent
the front (leading) end wall 128 to the rear (trailing) end wall
128' thereof. The slope of metal top 124 relative to the ground may
vary from one degree to about 45 degrees.
38. A layer of insulation 130 is located between top 124 and
infrared element 132 located therebelow. The major plane of
infrared heating element 132 is substantially parallel to the major
plane of metal top 124. Infrared heating element 132 is made of
metal or other heat absorbing material capable of generating
infrared radiation when heated, and is preferably corrugated with a
plurality of ridges 134 extending downwardly, and parallel to the
longitudinal side walls 126, as shown.
39. The upper surface of infrared heating element 132 is in contact
with the lower surface of insulation layer 130. The lower surface
of infrared heating element 132 faces toward the open bottom of
heater box 120.
40. A heater manifold enclosure 140 extends between side walls 126
adjacent the front end wall 128. Located inside manifold enclosure
40 is a U-shaped manifold pipe 42 communicating with a plurality of
burners 44 extending outwardly from manifold pipe 42 and manifold
enclosure 140 toward rear end wall 128', burners 44 being located
between and beneath the ridges 134 of infrared element 132, as
shown. Manifold pipe 42 communicates with a flexible or rigid
conduit 46 via union 47, and conduit 46 communicates manifold pipe
42 with a supply tank of flammable fuel (not shown), such as
propane. Such a propane tank may be mounted on the heater box 120
of apparatus 110, but it can be carried by the motorized vehicle to
which apparatus 110 is attached or in a separate trailer.
41. In operation of the second embodiment just discussed, thermal
weed killer 110 is mounted for movement across the ground in the
same manner as for apparatus 10, as illustrated in FIG. 1. Flames
from the outlets of propane burners 44 move across the underside of
the angled infrared heating element 132 toward the ground located
adjacent the bottom of rear end wall 128'. Such flames contact and
impact the target weeds located adjacent rear end wall 128' with
direct flames, thus increasing the treatment effects of the thermal
weed killer 10. In addition, the velocity of air supplied from
blower 48 can be adjusted to create turbulent hot air under the
angled infrared heating element 132 which moves downwardly across
the angled underside of heating element 132 toward the ground
located adjacent the bottom of rear end wall 128' where it contacts
target weeds, moving them about. This movement helps maximize
contact between the target weeds and the hot air, the infrared
energy from heating element 132, and the direct flames from the
burners 44. Together, the impact of these three thermal factors
enhances the vaporization of water from the leaf surfaces of the
previously sprayed weeds thereby maximizing the thermal weed
killing effect.
42. It will be obvious to those having skill in the art that many
changes may be made to the details of the above-described
embodiments of this invention without departing from the underlying
principles thereof. The scope of the present invention should,
therefore, be determined only by the following claims.
* * * * *