GB2136663A - Spraying apparatus - Google Patents

Abstract

Agricultural spraying apparatus for ultra-low volume spraying comprises a body 20 supporting one or more sprayheads 24 fed from a spray reservoir 8, the body being provided with a power-driven rotor 4, 5 for creating lift sufficient to support the weight of the body, and with a control line 3 for positioning the sprayer over a crop to be sprayed. <IMAGE>

Description

SPECIFICATION Spraying apparatus This invention relates to spraying apparatus, and more particularly to spraying apparatus for use in agriculture, in particular for use in ultra-low volume (ULV) spraying, In recent years the use of ULV spraying has increased considerably. The former practice of high.

volume spraying involved diluting pesticides with large volumes of water prior to use. This has disadvantages; in particular, water is not readily available in all situations, and even where it is available, considerable effort is necessary to transport it through the crop. At application rates of 0.5-2 litres per hectare, for example, one man can comfortably carry sufficient pesticide to treat a substantial area, provided ULV formations are used; but a vehicle such as a tractor will be needed if high volume application at rates of say 200-1,000 litresl hectare is used. Not only does a tractor used unnecessarily constitute a waste of capital and fossil fuel energy; in some circumstances its use may damage the crop. To take the case of paddy rice, for example, once the field is planted entry with a vehicle is quite impracticable.Even walking through the crops with a hand-held sprayer is difficult, particularly during the second half of the growing season.

An object of the present invention is to provide apparatus for use in agriculture, particularly well adapted for use with ULV spraying, which enables a crop or other target area for spraying to be treated without the need for wheeling a vehicle through the crop, or even to enter the crop at all, in some cases.

According to the present invention we provide an agricultural sprayer apparatus comprising a body carrying one or more sprayheads, a spray reservoir for delivering liquid to the sprayheads, at least one lifting fan and a motor for driving the fan so as to provide lift sufficient to support the sprayer against gravity and means for locating the body on a flexible line extending between two supports.

The invention is particularly suited to use with electrostatically charged sprays. In such uses the body will additionally carry a high voltage generator for charging the liquid.

The apparatus is useful in many situations where walking through crops is difficult or impossible. It may be useful with tail crops. It is particularly well suited to use in paddy rice.

Embodiments of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 represents an end view, partly in section of a device according to the invention in operation over a paddyfield.

Figure 2 represents an end view, partly in section, of a second device according to the invention in operation over a paddy field.

Figure 3 is a perspective schematic view of a third device according to the invention, provided with a vehicle attitude stabilising system.

Figure 4 is a top view of the device of Figure 3.

Referring initially to Figure 1, the device, adapted to be used by two operators, comprises a frame (20) supporting an electric motor (4). The shaft (21) of motor (4) extends upwardly and is fixed at its upper end (22) to a propellor (5), surrounded by a generally cylindrical safety cage (6). The frame (20) further supports a reservoir (8) containing spray liquid (23).

Reservoir (8) is connected by liquid conduits and a liquid supply tap (not shown) to pump (7) and thence to sprayheads (24) suspended from frame (20). The sprayheads (24) are surrounded by a removable flexible plastics skirt (10) (shown in section) depending downwardiy from frame (20). Frame (20) further carries a high voltage generator (25), capable of producing about 25KV as output; and a cableway (26) comprising four concave-rimmed guide wheels (27) for receiving a wire strand support cable (3) and a brake (28) for clamping the apparatus fixedly to the cable (3).

Motor (4), pump (7) and high voltage generator (25) are supplied with power from power cable (2) which includes an earth return wire. Power cable (2) is coiled around support cable (3), in the form of a resilient flexible large-coil spring, which at maximum extension is nearly as long as support cable (3). Power is supplied to power cable (2) by a combined petrol engine and electrical generator (1) supported on the back of an operator (30), or alternatively on a sledge or barrow (not shown).

In operation, the device is brought to the edge of an area which it is desired to spray, eg, a paddy field.

Cableway (26) is adjusted to an appropriate position on support cable (3) and locked in that position by means of brake (28). Two operators (30) and (31) position themselves on either side of the field with support cable (3) stretched taut between them.

Spare cable (3) is coiled on a carrier reel (9) supported on the back of operator (31). Operator (30) opens the liquid supply tap and starts engine/ generator (1), whereby electrical power is provided to the sprayer via power cable (2). This activates pump (7), generator (25) and motor (4). The latter rotates propeller (5) via shaft (21), generating as its speed is increased slightly more than enough lift to support the sprayer and the cables (2), (3) leading to it. Cable (3) serves to position the sprayer between operators (30) and (31) and to resist the torque of the rotating propeller (5). Operators (30) and (31) walk down the field at a rate appropriate to the rate at which liquid is supplied from nozzles (24) by pump (7). HT generator (25) meanwhile supplies 25KV to sprayheads (10), resulting in the production of fine charged spray particles of regular size.These are helped to penetrate into the crop by the downdraft from the propeller (5). At the end of the paddy, operator (30) reduces the speed of engine/generator (1), grounding the sprayer. Cableway (26) is then unlocked and moved along cable (3) towards operator (31), being relocked in position one swath width along the cable (3). Engine/generator (1) is restarted, spraying begins again, and operators (30) and (31) walk back up the paddy field to their starting point.

By repeating the process they are able to spray the whole area of the field.

Electric motors suffer from a low power/weight ratio, and electric generators are also heavy and cumbersome (though recent developments in batteries, eg. lithium/thionyl chloride batteries suggest that it may soon be possible to use high-power batteries to power engines in the device of our invention). Generally therefore we prefer to use petrol-driven motors.

A second embodiment of the invention is shown in Figure 2. This is generally similar to the device shown in Figure 1. Differences are that electric motor (4) is replaced by 3.5HP, 40cc two-stroke petrol engine (11). This drives shaft (21) and propeller (5) (diameter :2M) as before; its throttle is however controlled by a hand-held radio transmitter (12) carried by operator (30). Spray liquid (23) is carried in reservoir (8) as before; it feeds sprayheads (35) by gravity through a feed pipe and supply tap (not shown) which may either be operated by hand or servo-operated by a control signal from transmitter (30).

The sprayheads (35) are supplied with high potential (25KV) from a generator (36) powered by engine (11). Generator (36) is earthed via support cable (3).

Engine (11) also powers a reducing forward/reverse gearbox (37) which drives wheels (38), (39) in a cableway (42) for cable (3). The overall weight of the device is about 16kg, including a payload of about 5 kg.

In operation, the device is brought to the rice paddy as before. The operators (30), (31) stand one on each side of the paddy, the engine (11) is started, the supply tap opened and gear box (37) engaged in a forward direction. The thrust from propeller (5) supports the device while cableway (42) drives it slowly across the paddy while spraying the first swath until it reaches operator (31) on the further side. Operator (31) reverses gearbox (37), and both operators move one swath width further down the field, so that the device sprays a second swath parallel to the first as it returns to operator (30). By repeating this process the whole field may be sprayed.

The electrostatic sprayheads (24) are of the general type illustrated in Figures 7 and 8 of UK Patent 1569707, while the sprayheads (35) are of the general type illustrated in Figures 12 to 14 of that Patent. The disclosure of UK Patent 1569707 is incorporated herein by reference.

As will be apparent, numerous changes in the construction and mode of operation of the above described devices are possible and may be advantageous in certain circumstances. Features from the two devices can be combined in various ways : e.g.

the electrically driven device of Figure 1 may include the powered cableway and gearbox of the device of Figure 2 so that it is able to move along the cable (3) under power; the device of Figure 2 may include a pump to deliver spray liquid (this is generally preferred where suspensions are to be sprayed) or container (18) may be gas-pressurised. The speed at which gearbox (7) drives the cableway may be made variable. It will often be convenient to provide a trailing earth wire from cables (2) or (3) to provide an electrical pathway to earth. If electric power is being used solely to drive the high voltage generator (which in principle requires very little power and can be run off low power dry cells) a pathway to earth through one of the operators may be both sufficient and safe.

Where the apparatus is provided with a powered cableway to drive it along the cable (3), adjustable stops may be positioned on cable (3) at suitable distances from each operator as safety devices to prevent the sprayer over-running and contacting the operator. Further if desired the gearbox (37) may be provided with means whereby the drive is automatically reversed when the cableway contactsthe stop. In this way the sprayer will travel backwards and forwards automatically along cable (3) without the need for the operators to intervene. It is also possible for the vehicle to be driven along the cable by thrust from its fan.

As an alternative to the powered cableway illustrated, it is possible to use, for example, a cable in the form of a flexible tape, gripped between rubber driving wheels. Where the vehicle has a fixed position on the cable and is moved between the operators by use of the cable, the cable need not be continuous between the operators: it may be in two lengths, linked to opposite sides of the vehicle. In such an arrangement, the vehicle may be moved between the operators by winching. For example, one operator may control a motorised winch for winding in cable, while the other recovers cable using a linear spring; or both operators may have winches.

If desired, the operators may control the sprayer at a distance by means other than the transmitter (12) or the power cable (2). For example, one or more light control lines may be provided, for example, to set the throttle of engine (11); to open or shut the liquid supply tap; to set or release brake (28); orto reverse gearbox (37).

Other ways of operating the devices will be apparent. For example, if absolute evenness of spraying is not essential, in the case of the device of Figure 2 the operators can move slowly but continuously down the field so that there is a continuous small component of forward motion added tithe lateral movement of the sprayer. For certain applications (e.g. large glasshouses) operators could be dispensed with, and the device set to run automatically over a pre-set path. It will not always be necessary to ground the sprayer between traverses of the area being sprayed.

If desired, other types of sprayhead (e.g. uncharged spinning discs or cones) may be substituted for the electrically charged sprayheads used in the devices of Figures 1 and 2.

Flying vehicles suitable for use in the invention include those employing rotors and those employing ducted fans. Some are commercially available; an example is the remotely piloted vehicle CL-227 marketed by Canadair. Commercial vehicles, having usually been designed for other purposes that require them to have an airspeed of about 100 kph and an operating ceiling of several thousand meters, are extremely expensive, and it will generally be preferable to use a specially designed vehicle of lower capabilities. In designing such a vehicle, the problem of torque must be kept in mind. A vehicle with a single spinning propeller has substantial angular momentum. If the vehicle rolls or pitches slightly, a restoring moment in direct opposition to the vector of roll or pitch will, due to the gyroscopic effect, produce a couple at right angles to the vector.

This makes it difficult to correct any instability of the machine by tugging on the cable, because a tug on the cable in the direction which seems natural to the operator will cause the vehicle to tilt at right angles to the direction he wants.

Thus, to provide a conveniently handleable machine it is very desirable to eliminate or control the gyroscopic effect. It may be substantially eliminated, for example, by using two contra-rotating propellors to provide life (the CL-227 machine does this) or by providing a counter-rotating shaft or sleeve which balances the angular momentum of the propellor. Combined with suitable adjustment of the position of the centre of gravity, this gives a more stable vehicle. Also, (alternatively or additionally) the vehicle may be provided with a control system to counter-balance gyroscopic effects. One such system, used in many passenger-carrying helicopters, is that of cyclic pitch control. The pitch of the helicopter blades is varied as they turn through each complete revolution.If the vehicle, having a rotor rotating anti-clockwise (as viewed from above) pitches forward, the control system will increase the pitch on the blade as it passes through the semicircle to the right of the roll axis and reduce it as it passes through the semicircle to the left of the roll axis.

Changes in pitch produce corresponding changes in lift: the effect of these is to produce a gyroscopic couple acting against the forward pitching movement and tending to restore the system to stability.

Such control systems in passenger-carrying helicopters may be operated by the pilot; in unmanned systems they are preferably automatic. A useful automatic system which may be used in our invention is illustrated in Figures 3 and 4.

In Figures 3 and 4 a device according to our invention comprises a vehicle body 51 carrying within it a spray reservoir and an engine, the engine driving (anti-clockwise, as viewed from above) a shaft 52 carrying two rotor blades 49,50. These are pivotable about their long axis for pitch control.

Extending through the vehicle body 51 and mounted slideably therein is a vehicle control line 48. Mounted parallel to control line 48 is a sensor boom 54, carrying at each end a pitch sensor 56. At right angles to sensor boom 54 is mounted spray boom 53, carrying electrostatic nozzles 57 (fed from the spray reservoir by conduits not shown) and at each end thereof a roll sensor 56. The pitch and roll sensors 55, 56 are downwardly-directed ultrasonic range-finding sensors, of the type used in autofocus cameras. They produce an electrical signal whose strength is dependent on the distance from the ground, and is sufficiently sensitive to detect differences of less than 2 centimetres. The signals from each pair of sensors (pitch sensors 55 and roll sensors 56) are fed to a microprocessor, which controls via a relay the pitch of blades 49, 50.

The microprocessor compares each pair of signals an-d adjusts the pitch of the blades 49, 50 in each of the four quadrants through which they rotate. The pitch of the blades 49, 50 is controlled in the quadrants 61,62 whose centre lines lie over the roll axis 59 by the roll sensors 56; and correspondingly in the quadrants 63, 64 whose centre lines lie over the pitch axis 58 by the pitch sensors 55. If the vehicle pitches forward, so that pitch sensor 55a is nearer the ground than pitch sensor 55b, the microprocessor, in response to the differential in the signals between them, will increase the pitch of blades 49, 50 as they pass through quadrants 64, and correspondingly decrease it as they pass through quadrant 63.

Similarly, in response to a rolling motion to the right (roll sensor 56a lower than sensor 56b), the microprocessor will increase the pitch (and hence lift) of blades 49, 50 in quadrant 62 and decrease it in quadrant 61. At the same time, this system may be used to control height. To do this, the microprocessor can average the signal from ail four sensors 55, 56. If the distance to ground corresponding to the signal is too small, the microprocessor will increase the average or collective pitch (and hence lift) throughout the cycle until the height is correct; and correspondingly reduce this pitch if the height is too great.

As well as ultrasonic range-finders, infra red or other rangefinders may also be used for this purpose.

It is possible to operate the system with three sensors only, eg. at the corners of an equilateral triangle whose base is the pitch axis and whose apex lies on the roll axis. The two roll sensors on the pitch axis operate exactly as before: but the signal to restore pitch is obtained by comparison of the signal from the single pitch sensor with that of an average of the two roll sensors.

Claims (5)

1. An agricultural sprayer comprising a body carrying one or more sprayheads, a spray reservoir for delivering liquid to the sprayheads, at least one lifting fan and a motor for driving the fan so as to provide lift sufficient to support the sprayer against gravity and means for locating the body on a flexible line extending between two'supports.

2. A sprayer as claimed in ciaim 1 which further comprises a high voltage generator carried on the body for providing an electric charge to droplets produced at the sprayheads.

3. A sprayer as claimed in either of claims 1 or 2 wherein the means for locating the body on the line permit the body to move along the line.

4. A sprayer as claimed in any of claims 1 to 3 wherein means locatable at one end of the line are provided to control the rotor speed or spray rate of the sprayer.

5. A sprayer as claimed in claim 3 wherein the movement of the sprayer body along the line is limited by one or two stops.