Note: Descriptions are shown in the official language in which they were submitted.
2Q~o10
PS/57-17591/+/HOR 3
Device for applying plant-protectin~ compositions
The invention relates to a device according to the preamble of claim 1.
A device of this kind is known from EP-A-201 981 in which, in order to keep the
concentration of the active substance in the carrier fluid constant irrespective of the
driving speed of the tractor to which the device is attached, the volume of carrier fluid
supplied by the feed pump to the spray nozzles is controlled, as a function of the amount
of active substance added, by an electric control means that monitors one of the two fluid
flows. Although the amount of active substance is controlled as a function of the driving
speed, the concentration remains independent of the driving speed. The metering pump
for the active substance is driven by a motor. It is said, however, also to be possible for
the metering pump to be so designed that it is driven by the pressurised carrier fluid
supplied by the feed pump. How, in that case, the metering pump is designed, and how
the volume of carrier fluid is supposed to be controlled as a function of the amount of
active substance added, is not specified. In that device, keeping the soncentration of
active substance in the carrier fluid constant irrespective of the driving speed necessitates
a complicated control means that matches the drive of the feed pump to the amount of
active substance supplied. To adjust the concentration of the active substance in the
carrier fluid, the drive of the metering pump is modified by the control means, thus
requiring the control means to have a further function.
AU-B-504 816 discloses a device for metering a liquid fertilizer or the like into a stream
of water flowing through a main pipe, a reduction in pressure in the water flow being
produced by a reduction in cross-section, for example a Venturi nozzle, in the main pipe.
Pipelines are connected to the main pipe, one upstream and one downstream from this
reduction in cross-section, each of which leads to a pump that is connected by way of an
immersed pipe to a container housing the preparation. As a result of the higher pressure
in the pipeline connected upstrearn from the reduction in cross-section, a diaphragm
piston in the pump is acted upon, this piston, which is provided with valves and biassed
by a spring, sucking fertilizer out of the container, and the fertilizer being fed into the
main pipe through the pipeline connected downstream from the reduction in
20~Q~
-2 -
cross-section, in which the pressure is lower. In that device, a certain pressure difference
must be produced in the main line so that the force of the spring against the diaphragm
piston of the pump can be overcome and enable the pump to work. Accurate metering,
as is necessary for plant-protecting compositions, cannot be achieved with that device.
The adjustment of the concentration of fertilizer in the water flow has to be undertaken
by modifying the pressure difference in the main pipe. The concentration cannot be
adjusted accurately in this way.
Finally, DE-U-88 09 599 discloses a spraying device in the form of a hand-held spray
pipe, there being mounted at the outlet end of the spray pipe a one-way supplementary
fluid dispenser consisting of a cylindrical housing and a piston displaceably arranged
therein on a guide tube. Primary fluid from the spray pipe flows out through this guide
tube into an outlet nozzle on the supplementary fluid dispenser, whilst a partial flow of
the primary fluid acts on the piston, so that the supplementary fluid contained in the
supplementary fluid dispenser is forced by means of the piston into the outlet nozzle in
which it is mixed with the primary fluid emerging from the guide tube. Exact metering is
not possible with this device because it is not possible for the piston in the supplementary
fluid dispenser to be moved from its rest position by a small amount of primary fluid.
Also, because of the friction of the piston in the housing, meteAng cannot be
predetermined and adjustment of the concentration of supplementary fluid in the primary
fluid is not possible.
The problem underlying the invention is to design a device of the kind described at the
beginning in such a manner that reliable and precise metering is possible without a
complicated means for controlling the concentration of the plant-protecting composition
in the carrier fluid.
This problem is solved by the features in the characterising clause of claim 1. As a result
of the series connection of feed pump and metering pump in the pipe, it is not just a
partial flow but the whole of the carrier fluid flowing through the pipe that is used to drive
the drive element in the metering pump, as a result of which the plant-protecting
composition or preparation is reliably metered as a function of the volume of carrier fluid.
A complicated means for controlling the concentration of the preparation in the carrier
fluid is not necessary, because the concentration predetermined by the setting on the
metering means is automatically maintained even when the throughput of carrier fluid in
the pipe changes. Since the whole of the carrier fluid drives the metering means, a low
20~o~.~
throughput of carrier fluid means that a small amount of preparation is metered in, and a
larger throughput of carrier fluid that a correspondingly larger amount of preparation is
metered in. An adjustment of the concentration can easily be made on the metering
means.
In the construction according to the invention in which the drive element driven by the
carrier fluid is connected to a metering element, it is also possible to connect to the drive
element of the metering pump several meteling elements which are simultaneously
connected to different preparation containers each by a separate connecting pipe, it being
possible for the amount to be taken from each individual preparation container to be set
separately and independendy of the other preparation containers. Consequently, several
preparation containers can be connected to the device simultaneously in a simple design.
Advantageous forms of the invention are given in the other claims.
With reference to the drawings, aIrangements of the invention are explained in detail by
way of example in the following:
Fig. 1 is a schematic representation showing the arrangement of the essential elements of
the device,
Fig. 2 is an arrangement for the simultaneous connection of several preparation
containers, and
Fig. 3 is a schematic representation of a modular unit for insertion into a pipe.
In Figs. 1 and 2, reference numeral 1 denotes a tank for carrier fluid, usually water, which
may have, for example, a filling volume of approximately 5001. A feed pump 2 feeds
water from the tank 1 through a pipe 3 in which a spherical valve 4, a metering pump S
and a mixer 6 are arranged. Reference numeral 7 denotes a return pipe between the
spherical valve 4 and the tank 1. There is connected to the pipe 3 by way of a distributor
8 a spray bar having, for example, three part-width spray means 9, 9', 9", each of which
consists of a section of pipe provided with spray nozzles. The metering pump S is
connected by way of a connecting pipe 10 to a container 11 for plant-protecting
composition or preparation which may comprise a customary comrnercially available
plastics canister with a capacity of, for example, S 1.
The metering pump S sucks the plant-protecting composition, which is in liquid form, out
2(:~100~0
of the preparation container 11 and adds it to the water flowing through the metering
pump in such a manner that a certain amount of plant-protecting composition is added to
a certain volume of water.
A metering pump 5 is provided through which there flows all of the water that is fed by
the feed pump 2 through the pipe 3, and as a result of this flow of water a drive element,
for example in the form of a piston 12 in the metering pump 5, is so driven that the piston
12 executes a reciprocating movement. Connected to the piston 12 is a metering device,
which in the diagram is in the form of a hollow metering piston 13 provided with a return
valve and displaceable in a cylinder 14. In order to set the effective sucking stroke of the
metering piston 13, a setting sleeve 15 is attached to the cylinder 14 by means of which
the concentration of the preparation in the carrier fluid, that is to say the amount of
preparation sucked up, can be set. This metering means is connected by the connecting
pipe 10 to the preparation container 11 and conveys preparation out of the preparation
container through the hollow metering piston 13 into the stroke chamber of the piston 12
from which the preparation, together with the carrier fluid, passes into the pipe 3 leading
to the mixer 6.
In the diagram of the metering pump 5, reference numeral 16 denotes valves that, as a
function of the piston movement, alternately free the inlet for the carrier fluid into the
chamber above the piston 12 and at the same time the outlet of the chamber below the
piston, whilst the other valves are closed, and vice versa. These valves 16 are reversed by
the pressurised carrier fluid and the piston movement. This volume-controlled metering
pump thus operates without outside energy.
The metering pump S used is preferably that described in DE- C-37 07 186. A suitable
metering means with a metering piston secured to the diaphragm piston of the metering
pump in accordance with DE-C-37 07 186 is described in DE-C-24 15 109. By means of
the setting sleeve of this metering means it is possible to set, for example, an amount of
from 0.05 to 10 l/ha of preparation at a water application volume of 100 to 600 Vha,
irrespective of the driving speed.
Instead of the described metering pump S with piston 12 and metering piston 13 attached
thereto it is also possible to use a different pump construction in which a rotatably
mounted drive element, for example a bucket wheel, is driven by the carrier fluid, in
which the rotating bucket wheel is connected to a metenng means having a rotatable
2010010
metering element that sucks preparation from the container and conveys it into the flow of
calTier fluid through the metering pump 5 and into the pipe 3.
To ensure thorough mixing of the preparation with the carrier fluid to which it is added,
there is connected downstream from the metering pump 5 a mixer 6, which in the
arrangement shown has a downwardly tapering mixing chamber with an immersed pipeprojecting into the lower portion of the mixing chamber. This arrangement of a mixer
operates according to the cyclone principle and ensures uniform mixing of the spray
liquid. The conical shape in addition ensures that the viscosity does not influence the
fluids to be mixed, so that it is also possible to use highly viscous compositions.
Although a highly viscous composition can be accurately metered by the mete~ing pump
5 a good mix cannot be obtained at the same time. This is guaranteed by the mixer 6,
which can also be of a different design from that shown.
The volume of the mixing chamber is advantageously adjusted to that volume whichcorresponds to one stroke of the piston 12 in the metering pump 5. Preferably, the
volume of the mixing chamber is equal to the reference volume displaced in the metering
pump 5 with one dose.
The connecting paths between metering pump 5 and distributor 8 of the spray bars are
kept as short as possible. As a result of the thorough rnixing of the spray liquid in the
mixer 6, it does not require any further mixing in the pipes through which the spray liquid
flows. Similarly, the connecting line 10 between metering means and preparation
container 11 is designed to be as short as possible so as to keep the contaminated areas of
the device to a minimum.
On operation of the device attached, for example, to a tractor, the water flow to the
metering pump 5 is controlled as function of the driving speed. After switching on the
feed pump 2, it takes a very short start-up dme of, for example, 10 to 15 seconds, to build
up a constant concentration of spray liquid which can then be maintained withoutfluctuations. The commencement of spraying in the field can thus be very accurately
controlled. As a result of the direct feeding by means of the metering pump 5, only a
small portion of the spray liquid necessary for the entire spraying operation is in the
device at any time. This assists in keeping the concentration of spray liquid constant.
When the spraying operation is complete the application OI the spraying liquid can be
- ~ ,
201~0~0
- 6-
terminated very quickly because there is only a small predetermined amount of spray
liquid in the device between the metering pump 5 and spray nozzles on the spray bars.
This amount may, for example, correspond to the amount required for the last 10 metres'
driving distance to be treated. Consequently the short portions of pipe contaminated by
spray liquid can be cleaned very simply. For this purpose a change-over valve 17 is
provided in the connecting pipe 10 between the metering means and preparation container
11 by means of which it is possible from the driver's seat to connect the metering means
by way of pipe 19 to a portion of the pipe 3 conveying water only, or to the tank 1, or to a
separate water container that is not shown. Shortly before the end of the spraying
operation, the metering pump 5 can be connected to the pipe 3 or the tank 1 so that the
contarninated region between metering pump 5 and spray nozzles is washed with water
and thus cleaned.
To connect the preparation container 11 to the connecting pipe 10, it is advantageous to
provide a rapid closure, indicated by reference numeral 18 in the diagram, by means of
which the container 11 can be connected quickly and simply to the device. A sealing cap
provided with an immersed pipe may be provided in the container 11, to which cap the
connecting pipe 10 can be directly connected by means of a rapid coupling, so that the
immersed pipe remains in the container 11 permanently.
Figure 2 shows an arrangement in which there are secured to the piston 12 of the metering
pump 5, for example three metering pistons 13, 13', 13", each of which is associated
with a cylinder having a setting sleeve and is connected to a separate preparation container
11, 11', 11". In this manner several preparation containers can be connected to a single
metering pump 5 simultaneously, it being possible for the dose to be taken from each
individual preparation container to be set separately at the respective setting sleeve 15.
If metering pistons 13 are mounted at opposite sides of the piston 12, then up to eight
different preparation containers may simultaneously be connected by the metering pump
5, in which case eight different preparations of different dosages can be fed into the
carrier fluid.
If a metering pump with a rotatable drive element is used instead of a reciprocating piston
12, then it is also possible for several metering means to be operated, for example by
means of a toothed wheel that is attached to the rotatable drive element and engages with
other toothed wheels on various metering means.
.
.
2010010
Fig. 2 also shows an arrangement of a computer-controlled device. Connected to acomputer 22 is a revolution sensor 23 which, by way of the number of revolutions of the
drive shaft 24 or of a wheel of the tractor, detects the speed and conveys this to the
computer 22. A flow measuring device 25 feeds to the computer 22 signals that
correspond to the rate of flow of water in the pipe 3. Also connected to the computer æ
is a control circuit 26 for the individual part-widths, which is connected by way of
connecting lines (shown by broken lines) to valves (not shown) in the individualpart-widths 9, 9', 9". A further connecting line from the computer 22 leads to the
spherical valve 4 for the purpose of controlling the throughput of carrier fluid or water to
the metering pump. It is also possible, using the computer 22, to control the drive motor
of the feed pump 2 as a function of the driving speed or some other parameter.
Before operation begins, the flow meter 25 and the revolution sensor 23 are calibrated to
determine the driving distance, and the values of amount to be applied and number of
part-widths or number of nozzles per part-width are fed into the computer 22. By way of
the connection to the control circuit 26 the computer 22 is informed whether and which of
the part-widths are connected. During the spraying operation signals relating to distance
and flow in the pipe 3 are continuously fed to the computer, which compares the
predetermined reference value with the actual value corresponding to the incoming
signals and, when there are variations from the reference value, controls the spherical
valve 4, by means of which the throughput in the pipe 3 is appropriately influenced by
pressure control. In this manner the predetermined amount of water applied is monitored
and adjusted to avoid an under- or over-dose as a result of variations in driving speed.
According to a further arrangement, directly following the mixer 6 it is possible to exa-
rnine the concentration of the spraying liquid by means of a suitable device that feeds the
ascertained concentration to the computer 22 which compares this actual value with a re-
ference value and, where there is a difference, controls the setting sleeve 15 on the meter-
ing means accordingly so as to bring the actual value in line with the reference value.
It is also possible to provide on the metering pump a signal transmitter that monitors the
operation of the metering pump 5 and, if there is an interruption in operation of the
metering pump 5, gives an acoustic or optical alarm signal in the driver's cabin. Such a
monitoring device can also be connected to the afore-described concentration-examining
device, so that an alarm signal is given to the driver if the concentration of spray liquid
20~00~0
- B -
differs too much from the reference value.
The change-over valve 17 is advantageously designed to be electromagnetically
controllable from the driver's cabin so that it is possible to switch over to washing shortly
before the end of the spraying operation.
To render possible operation of the device in a conventional manner, a bypass pipe 27
may be provided which is connected to the pipe 3 by way of change-over valves or 3-way
valves 28, 29 upstream from the metering pump 5 and downstream from the mixer 6 and
circumvents the metering pump S and the mixer 6. This bypass pipe 27 is also
advantageous for using the device for applying fer~ilizer where metering by the metering
pump 5 is not required.
Any plant-protection apparatus can be fitted with the described device. For this purpose
there is advantageously provided a modular unit comprising metering pump 5 with
metering means 13, 14, lS and, if desired, the mixer 6, which is provided with
corresponding connections so that the modular unit can be inserted into an existing pipe 3
of a spraying apparatus. There is advantageously integrated into this modular unit a
holder for the preparation container 11 and a rapid closure for the connection thereof. In
order to protect this modular unit against contamination by dust and splashes, it is
preferably of encapsulated design, as indicated schematically in Fig. 3 in which the
modular unit is denoted by 30. Reference numeral 31 denotes resilient tube portions that
are provided for connection to the pipe 3 of a spraying apparatus and protect the modular
unit 30 against vibrations during the spraying operation. A connection for the washing
pipe 19 is provided at 32 on the modular unit 30, in which case it is possible for the
change-over valve 17 to be integrated into the modular unit 30.
Instead of a container 11 with a liquid preparation, a container with pulverulent or
granular preparation may be provided, wherein it is possible for this preparation to be
prepared by admixing water in a mixing container and then for the preparation, then in
paste form, to be taken from that rnixing container by the metering means 13, 14, 15. In
such an arrangement an agitator would have to be provided in the mixing container.
Monitoring the operation of the metering pump can also be undertaken by a switch in the
connecting or suction pipe 10 of the metering pump 5. The described device can be
attached not only to a tractor but also to an aeroplane.
.
- '
