Note: Descriptions are shown in the official language in which they were submitted.
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SPRAYING APPARATUS EMPLOYING A SKIRT STRUCTURE
Field of the Invention
The present invention is concerned with improvements
in or relating to spraying apparatus, and especially to such
apparatus employing an air-supported skirt structure.
Review of the Prior Art
Repeated carefully controlled spraying is now an
essential part of any agricultural operation. With increases in
the toxicity and cost of spray materials it becomes more and more ---
essential to achieve uniform application and to avoid unwanted
drift of the finely divided material. Thus, insufficient or too
great application is of course wasteful-of the material itself,
but with many modern spray materials excessive application can
even damage the crop'plant. Again many modern materials are
sufficiently hazardous that the operators must wear special
protective clothing and'take special handling precautions. Many
authorities now have enforced regulations as to weather conditions
in which spraying can take place; for example with some materials
the Province of Ontario, Canada, will not permit spraying if
the wind speed is higher than 7 m.p.h. (11 k.p.h.) while with
some chemicals it is considered imprudent to operate if the wind
speeds are higher than 4 m.p.h. (6.4 k.p.h.).
One particular form of skirt structure employed
hitherto consists of a peripheral air bag or bags which are
'inflated by the pressurised air. One of the proble~s encountered
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with any type of air-~upported vehicle hitherto is the relatlvely
hi~h co~t of the air-enclosi~g skirt, and it is a constant
endeavour to provide as inexpensive a construction as posslble.
Definition of the Invention
It i~ an object of the invention to provide a new bag skirt
structure for air-supported a~paratus.
In accordance with the present invention there is provided
a bag skirt structure for an air-supported apparatus comprising
two spaced parallel air-receiving passages surrounding an air-
receiving enclosure open to the ground and constituting respective
parts of at least one air bag, and an end closure member for clos
ing the adjacent ends of the said spaced parallel pa~sage~ and also
the respective end of the said enclosure ~e*q~ the closure member
comprising an envelope disposed over the adjacent ends of the said
spaced parallel passages and overlapping said ends, wherein the
air received in the passages expands the respective portions of the
passages within the envelope into sealing engagement with the
envelope.
Such a bag skirt construction preferably includes fa~tening
means fastening a portion of the said passage~ to a portion of the
envelope to retain the envelope thereon.
Said fastening means may comprise a first batten fastened
to the upper surface of an upper portion of the said spaced passages
to extend between them, and a second batten fastened to the lower
edge of the envelope between the said two passage~,-and means for
fastening the two battens to one another.
The said spaced parallel passages may be formed by folding
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inwards the edges of a longitudinal stxip of flexible material
and fastening the said edges to the strip in spaced parallel
relationship whereby the part of the strip between the
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said edges constitutes a roof for the space between the said
passages.
A complete bag skirt comprises two air receiving
passages having both their ends open, and two side-opening
envelopes each disposed over two respective adjacent ends and
fastened thereto.
Description of the Drawings
A spray apparatus employing an air bag structure which
is a particular preferred embodiment of the invention will now be
described by way of example, with reference to the accompanying
diagrammatic drawings wherein:
FIGURE 1 is a general perspective view showing the
spray apparatus together with a liquid supply tank and tractor
therefor;
FIGURE 2 is a similar view to a larger scale showing
the spray apparatus and a part only of the liquid supply tank;
FIGURE 3 is a cross-section on the line 5-5 of
Figure 2;
FIGURE 4 is a perspective view from below of part of
the spray apparatus with part of one of the skirt bags shown
broken away to reveal the spray nozzles;
FIGURE 5 is a section on the line 5-5 of Figure 4 to
show the manner of mounting a nozzle;
FIGURE 6 is a section on the line 6-6 of Figure 3 to
show the manner of mounting a nozzle support;
FIGURE 7 is a cross-section taken on line 7-7 of
Figure 2;
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FIGURE 8 is an exploded view of the end of the bag
skirt; and
FIGURE 9 is a cross-section on the line 9-9 of
Figure 2.
Description of the Preferred Embodiments
A complete agricultural sprayer consists of a tractor
10 pulling aliquid supply tank 12, which in turn tows behind it
the spray apparatus 14. In other embodiments the liquid supply tank
can be mounted on the tractor which tows the apparatus 14 directly
via the usual three point hitch. More particularly the tank 12
is provided at its rear end with a small hoist derrick 16 on which
is mounted a winch 18. The winch cable 20 is fastened by chains to
the top of a circular fan housing 22 mounting a fan 24. In this
embodiment the fan housing is connected by support chains 26 and
a flexible tubular plenum member 28 to a rectangular metal frame
member 30. The fan 24 is driven, as is also the winch 18, by
power supplied in any well known manner from the tractor. It will
be apparent that the we~ght of the spray apparatus 14 is thereby
minimized, as many as possible of the parts of the complete
sprayer being carried by the tractor 10 and/or the tank 12.
Th~ housing frame member 30 is pivotally connected
by rigid draw struts 32 to the rear end of the tahk 12 and serves
as the convenient anchor point for two oppositely-extending spray
boom frames, each of which consists of two spaced parallel rods
34 connected together by spaced parallel cross-members 36. In
this embodiment each rod 34 is divided about mid-way of its length
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into two sections 34a and 34b pivotally hinged to one another at
38, while the inboard rod sections 26a are pivotally hinged at
40 to the frame member 30, so that for storage and transport each
boom can be folded with the sections 26a extending upwards and
the sections 26b extending downwards close and parallel to the
sections 26a. This lifting into the storage and transport position
is effected by means of respective winches 42 mounted on the hoist
16 and connected by cables 44 to a respective cross member 36.
It will be appreciated that in other embodiments the rods may be
divided into more than two sections suitably pivoted to one another.
The hinges at 38 permit the above-described folding, and sufficient
upward hinging for the boom to be able to follow the ground directly
underneath it. The hinges at 40 must of course permit ninety
~ degree movement of the booms upward, together with a smaller but
sufficient downward movement. The spray boom frames are completed
by arcuate front and back downward-extending sections 46 hinged at
48 to the rods 34 to permit upward movement for storage, as
illustrated by Figure 3.
The spray boom frames hold a peripheral flexible
bag skirt structure 50 in extension, and are in turn supported by
the skirt structure from the ground under the effect of the air that
is injected under pressure by the fan 24 into an enclosure 52 formed
by the skirt. In this particular embodiment the bag skirt is formed
from an elongated strip of suitable material, e.g. heavy polyvinyl
5 sheet, by folding the edge portions of the sheet toward ~ts centre
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and fastening them to the centre part of the body along spaced
parallel lines, as at 54 in Figures 3 and 7. As best seen in
Figures 3,4, 7 and 8 there are thus formed two elongated, parallel
enclosed passages 56 each of which is supplied with air from the
fan via respective openings 58 (Figure 7) in the floor of the
frame 30. The passages are physically connected by the centre
portion 60 of the elongated strip constituting a roof for the spray
zone enclosure 52, this enclosure having the two air passages 56
as its respective longer side walls, and into which air is fed
from the passages via apertures 62 and 64 in the passage inside
walls. Such a skirt is commonly called a bag skirt in that it
consists ~ther of a single peripheral bag, or alternatively of a
number of bags arranged around the periphery of the structure to
be supported thereby. The bag skirt structure is connected to the
rods 26a and 26b and frames 46 by loops 66 of the flexible skirt
material through which the frame rods are threaded.
Since in this embodiment the bag skirt is required to
enclose a spray zone constituted by the enclosure 52, it is desired
that it be substantially continuous around the periphery of the
enclosure, and difficulty has always been experienced hitherto in
poviding a relatively inexpensive method of forming the bag ends of
a bag skirt. In accordance with this invention such end closures
are provided by means of two open-sided envelopes 68 which are
slipped over the respective ends of the above-described strip-formed
passages. A rigid batten 70 is provided on the upper`sur~ace of
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the strip mounted within a sleeve 72, and is of sufficient length
to hold the bags to the required shape at the respetive locations.
The central portion of the envelope lower edge carries a shorter
rigid batten 74 on a sleeve 76, which is then lifted up into the
enclosure until it touches the roof underside; the two battens 70
and 74 are then fastened together by lashings 78 passing through
the roof around the battens. A substantial overlap is provided
between each envelope and the adjacent portion of the strip and
it is found that, as the passages 56 are inflated they expand
inside the envelope and hold it sufficiently firmly to be
retalned without any substantial leakage during normal operating
conditions.
Such an end closure avoids the need for relatively
expensive seaming and joining operations between the passage-
forming strip and the end-closing envelopes. It will be seen
that the passage structure can readily be formed continuously,
the desired length cut therefrom as required and the end closures
applied. If the air-sealing between the passage structure and the
end closures is not quite sufficient it can be improved by making
the latter of just slightly smaller periphery than the former,
so that they are forced into even more intimate contact by the
internal air pressure.
As described above, each pair of parallel rods 32a
and 34b is connected by cross-members 36, the ends of which are
removably fastened to the respective rods, so that the boom can
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readily be disassembled for removal of the skirt. Each cross-
member 36 has at its centre a downwardly-extending U-bolt clamp
80, the legs of which pass through apertures in the enclosure
roof 60, flanges 82 being provided on the bolt legs against which
the material is clamped to permit an air-tight seal to be maintained
where the legs pass through the material. L-section spray nozzle
support member sections 84a and 84b are fixed to the bights of
the respective clamps, separate sections being used to permit the
above-described folding for storage, etc. A plurality of spray-
nozzles 86 are mounted on each support member 84 so as to beadjustable in position along its length, permitting the nozzles
to be located as required relative to the rows of the crop to be
sprayed. Thus each nozzle is fastened to a bracket 88 (Figure 7)
which embraces the lower horizontal leg of the support, and can
be clamped thereto by a set screw 90. ~he nozzles are supplied
with spray liquid or finely powdered material under pressure from
the tank 12 via flexible connecting hoses 92 (not shown in Figures
1 & 2).
In operation, with the fan housing 22 suspended at a
suitable height from the derrick 16, the fan 24 is started and the
skirt air bags inflate, the air discharging into the enclosure 42
through the apertures 62 and 64, as indicated by the arrows 92 in
Figure 3. The arcuate downwardly-extending frame portions 46
support the sides of the inflated bags as the sprayer is moved for-
ward or backward. Thus the weight of the spray apparatus 14 issupported by the pressurized air with the lower edge of the bag skirt
structure sufficiently close to the surface over which it is passing
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to brush it, so that a minimum of the air escapes from the
enclosure 52, minimizing both the power required to pressurize ~~
the air and the possibility of drift of air entrained material
from the enclosure. The amount of air escaping will increase with
increasing "porosity" of the surface to the outgoing air, due for
example to the presence of a growing crop, as the boom pulled behin~
the tractor passes over the rows of crop being sprayed, but this
escape is downward into the porous surface again minimizing sideways
drift.
10. In this particular embodiment the pressurised air
is fed first to the interior of the bag skirt structure and
thereafter to the enclosure 52, but in other embodiments the bag
skirt structure may be pressurised separately.
The direction of movement of the boom is indicated
by the arrow 96 in Figure 3, and it will be noted that the aperture
62 in the leading passage 56 is disposed relatively close to the
ground, while the aperture 64 in the trailing passage 56 is
located close to the enclosure roof 60. It will also be noted
that the effect.of the passage of the apparatus over the crop is ~.
-20 to bend the plants in the direction of movement. . The enclosure 52 ~ ~-
provides a virtually wind-free volume into which the spray is
- directed, the major part constituted by the larger droplets
discharging downwards, as with a conventional spray boom, so as
to coat the uppermost surfaces of the crop and the ground directly
below. A minor.part constituted mainly by the smaller droplets
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will be entrained by the air streams from the apertures 62 and 64
to be deposited on the crop under surfaces. The forward aperture
should also be the lower aperture to optimise this effect on the
forward-bending crop. This effect ensures to a much greater extend
than is possible with unenclosed sprays that the plants are fully
and uniformly exposed to the spray material. Nevertheless, little
or no spray material can escape from the enclosure.
The apertures 62 and 64 can con~ist of a large number
of small closely-spaced holes, formed directly in the material of
the bag skirt, but conveniently they are elongated slots, as
illustrated, with the parallel edges connected by elongated strips
98 of mesh material through which the air can flow. With this
particular structure the air is fed into the enclosure 52 uniformly
from the front and rear air bags over the entire length of the boom,
to reduce as much as possible undesired transverse movement of the
air in the enclosure, such transverse movement causing distortion
of the spray pattern.
It will be understood that the profile of a bag skirt
structure must always be a smooth curve providlng for smooth and
progressive entry and exit of the crop to and from the skirt
enclosure, minimizing damage to the crop over which it is passing.
This must be contrasted with the effect that would be obtained with
a vertical skirt, the lower edge of which would act as a form of
scraper blade with its potential damage, particularly to a tender
new crop. Furthermore, this shape in cooperation with the surface
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over which it passes constitutes a diffuser passage of progressively
increasing area to the escaping air, so that the air discharge
velocity drops abruptly immediately after passing through the
narrowest part of the passage. The support of the apparatus boom
in this manner ensures that the weight of each boom is uniformly
distributed over a substantial area and there is no need for out-
rigger wheels, with their possibility of damage. The winch 18 can
be adjusted at any time to adjust the height of the fan housing 22
above the ground. The use of an air-supported structure is found
to result in an "averaging" effect upon the height of the spray
dispensing nozzles above the ground, and this is believed to be of
importance in achieving an improved consistent spraying effect.
Thus, in conventional wheeled apparatus adjacent wheels may be
down in rut, hole or furrow and on top of a mound or hillock, so
lS that the height of the respective nozzles is very different. Again
the too-fast travel of prior art apparatus over rough ground causes
whipping movement of the boom, both vertically and laterally,
destroying the uniformity of the spray pattern. With the apparatus
of the invention such changes in ground contour are averaged over the
length of the boom to a much more constant value and boom whipping
is eliminated.
This maintenance of the spray dispensers at a sub-
stantially constant height above the ground, gives a uniform spray
pattern, as is desired with many modern materials where the rate of
application must be closely controlled for most effective results.
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Since the spray material is discharged into an effectively almost-
fully-closed enclosure there lS considerably reduced possibility
of spray drift, and the small rate found is in any case virtually
independent of wind cor.ditions, so that spraying can be done under
any conditions in which the air bags forming the skirt remain
sufficiently stable despite their quite high "windage". In this
respect it may be noted that when the wind has an appreciable
"follcwing" component the links 20 may be under compression, since
the booms may be blown toward the tractor faster than they are
being pulled.
Again owing to the physical characteristics of this new
spray apparatus, and particularly the manner in which it is
supported from the ground, it is possible to use relatively long
booms, and apparatus of a total length of 200 feet (60 meters) is
readily operable. ~oreover, the apparatus can be moved over the
crop at relatively higher speeds, since it does not create its
own "windage" in its passage, remembering the very low wind speeds
that are recommended for many modern materials. With the con-
struction illustrated the skirt is readily removed for trans-
portation and storage of the apparatus, and can easily be replacedin case of damage and/or wear.
Although the invention has been described as applied
to an agricultural sprayer, it will be apparent to those skilled
in the art that it is applicable to other spraying operations
in which the close confinement o~ the spray material and/or
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removal of the need ~or outrigger supports running on the ground
are desirable features.
