GB2153193A - Spraying apparatus - Google Patents

Abstract

Apparatus for spraying ground with liquid or slurry for agricultural or industrial purposes comprises a carriage (1) a pair of liquid spray jets (5) mounted on the carriage and connected to a supply of liquid under pressure, an unenclosed turbine wheel (4) positioned so as to be rotated by liquid issuing from the spray jets (5) and a cable winch (11) driven from a gearbox (10) coupled to the turbine wheel (4). Such apparatus is characterised in that the axis of the turbine wheel (4) is substantially parallel to the direction of motion of the sledge (1) and that the spray jets (5) face in opposite directions so as to spray liquid under pressure into respective tunnel-like spaces on each side of the sledge (1), each such tunnel-like space comprising a pair of flexible sheet material curtains which are suspended close to the ground from a framework projecting laterally of the direction of movement of the sledge. <IMAGE>

Description

SPECIFICATION Improvements relating to field spraying apparatus This invention relates to apparatus for spraying fields with slurry or liquid for agricultural or industrial purposes and of the kind comprising a carriage or sledge which carries a spray head and which is propelled across the ground by a mechanism driven by the pressure of liquid continuously supplied thereto.

Known apparatus of this kind has comprised a spray projector, otherwise known as a Turbogun, mounted on the carriage or sledge and caused to rotate or angularly oscillate about its vertical axis by being connected to a revolving crank.

A limitation of this known apparatus is the environmental nuisance created when a jet of offensive liquid is projected upwards into the air by the action of the Turbogun. A further limitation is the uneven distribution on the ground which results from the jets trajectory being distorted by the wind.

There has already also been proposed and used a field spraying apparatus of the kind referred to, which comprises on its carriage a rotatably mounted spray head and an unenclosed turbine wheel drivably connected to a cable winch and to the spray head whereby when the turbine wheel is rotated by a jet of liquid issuing from the spray head the spray head is rotated or angularly oscillated about a vertical axis at the same time as the winch is rotated so as to coil an anchored cable thereon and thereby propel the sledge over the ground which is to be sprayed.

Field spraying apparatus as above described has functioned efficiently but has not proved entirely satisfactory from the environmental point of view owing to wind drift of the liquid.

Thus the present invention has been devised with the object of eliminating or mitigating this nuisance and at the same time maintaining or improving functional efficiency.

In accordance with the present invention apparatus for spraying the ground with liquid or slurry for agricultural or industrial purposes comprises a carriage, a pair of liquid spray jets mounted on the carriage and connected to a supply of liquid under pressure, an unenclosed turbine wheel positioned so as to be rotated by liquid issuing from the spray jets, and a cable winch driven from a gearbox coupled to the turbine wheel, characterised in that the turbine wheel axis is substantially parallel to the direction of motion of the carriage and that the spray jets face in opposite directions so as to spray liquid under pressure into respective tunnel-like spaces on each side of the carriage, each such tunnellike space comprising a pair of flexible sheet material curtains which are suspended close to the ground from a framework projecting laterally of the direction of motion of the carriage.

Preferably the curtains of each pair are separated by a distance such that the irnpingement of the liquid spray on their inward facing surfaces causes the curtains to close together along their bottom edges. This causes stray or surplus particles of liquid to cohere and issue as droplets from the bottom of the curtains instead of entering the environment. Also, since the curtains are suspended within a few inches of the ground, there is a marked reduction of atmospheric smell when slurry is distributed.

A preferred embodiment of the ground spraying apparatus of the invention is hereinafter described with reference to the accompanying drawings in which: Fig. 1 is an overall rear elevation of ihe spraying apparatus; Fig. 2 is a rear elevation of a sledge forming part of the spraying apparatus; and Fig. 3 is a side elevation of the sledge.

Referring firstly to Fig. 1 the apparatus essentially comprises a carriage in the form of a sledge 1 which rests on the ground and is coupled to a remotely anchored ground cable and to a hose through which liquid is supplied under pressure. Extending laterally from each side of the sledge is a suitably braced double boom 2 from which there is supported in closely spaced relation a pair of curtains 3 made of flexible plastics sheet material which almost touch the ground. Each pair of curtains defines a tunnel into which slurry from a spray jet, which also drives a turbine wheel, is discharged so as to fall onto the ground.

Fig. 2 shows the rear of the sledge 1 from which a rear cover sheet has been removed to expose a turbine wheel 4 having its axis parallel with the direction of motion of the apparatus and which is driven by jets issuing from a pair of spray heads 5 which face laterally in opposite directions at an angle such as to cause liquid also to be sprayed into the respective tunnels defined by the already mentioned booms 2 and flexible curtains 3.

Also shown, is the liquid supply pipe 6 with branches 7. A suitable liquid supply pressure is 50 p.s.i.

Fig. 3 shows, in addition to components already mentioned, an output sprocket 8 from a pair of bevel gears (not shown) driven by the turbine wheel 4. The sprocket 8 drives, through a chain 9, the input shaft of a reduction gearbox 10 of which the output shaft drives through a chain, a cable winch drum 11 around which a ground cable 1 2 is wound (and unwound) to move the sledge across the ground at an appropriate speed of up to 1 2 feet per minute. The cable drum 11 has a retractable pin 1 3 by which it is drivably engaged with its drive sprocket (not shown) and which when retracted allows the cable 1 2 to be unwound and re-anchored for a subse quent run across the ground.Also shown in Fig. 3 is a speed regulation lever 14 which is latchable at various positions around a quadrant 1 5 and which axially adjusts the position of a rod 1 6 to which it is pivotally connected and which, being fixed at its opposite end to a plate which carries the spray jets 5 adjusts the position of the latter in relation to the turbine wheel 4. Thus, backward movement of the whole jet assembly causes the jets to disengage from the blades of the turbine wheel for a stationary situation, whereas progressive forward movement of the assembly brings the jets into deeper contact with the turbine wheel blades. This enables the rotational speed of the turbine wheel to be infinitely varied and enables any desired forward speed to be readily achieved.

Conveniently, the turbine wheel 4 has 23 blades and is about 20cm in diameter measured over the blade tips. The blades are welded on to a hub, At 90 to the jets at a pitch of 20mm and are connected by a large diameter annulus at the front of the turbine wheel. This disposition has been found to yield the most efficient production of driving power with minimum jet interference or disfiguration. Jet interference reduces the overall spray width which can be achieved, whilst jet disfiguration also reduces the reach of the jets into the tunnels formed between the pairs of curtains and causes increased impact between the liquid and the entry point of the curtains.

In turn this causes excessive application of liquid on to the ground adjacent the turbine wheel.

The angular disposition of the spray jets 5 is also adjustable and whilst they could be directed at 90 to the direction of travel of the spraying apparatus they may in fact be inclined slightly forwards, for no other reason than that it allows the curtains themselves to be forwardly inclined so as to transfer some of the weight of the boom and curtain structure to the front of the sledge unit.

A typical overall length for each of the pairs of booms is 6.3m and the distance between the mounting point of each pair of booms to each side of the sledges is 90cm, giving an overall distance from the centre of the turbine to the tip of each boom of 3.75m. The width between the booms of each pair at a point adjacent the sledge unit is 380mm, tapering off to only 160mm at the outer end of each boom pair. Typically, the depth of each curtain adjacent the chassis is 750mm and this depth is maintained to a point halfway along the boom structure, beyond which the top of the boom is allowed to slope downwardly towards the ground so that the depth of the curtains at the outer end of the boom structure is only 480mm.

It has been found that an increase or decrease in jet pressure from 50 p.s.i. does not have any real effect on the closing together of the curtains to produce the desirable effect of eliminating wind drift. However lowering the pressure does have a marked effect on the power output of the turbine and thus the potential forward speed of the apparatus, together with a reduction in overall jet length.

The effect of increasing the pressure significantly above 50 p.s.i. produces turbine power in an excess of the maximum required and also causes the liquid jets to be projected beyond the end of the curtains which is undesirable.

The inclination of the spray heads is preferably adjusted so that taking account of the deflection which occurs in the liquid jets as a result of impact with the turbine wheel the jets do not travel parallel with the ground but initially rise from near ground level to the centre of the apparatus to a maximum height so as to touch that part of the curtains which bridges the booms of each pair at a point about halfway along the boom. Beyond this point the liquid jet falls off towards ground level. The result of this spray pattern is that the bottom edges of the curtain are drawn together and have the effect of concentrating the liquid spray particles into a row of droplets which fall from the drawn-together lower edges of the curtains at a uniform rate along the length of the boom.

Whilst a carriage in the form of a sledge has been particularly described it is to be understood that the carriage could alternatively be a wheeled chassis if so required.

Claims (5)

1. Apparatus for spraying ground with liquid or slurry for agricultural or industrial purposes comprising a carriage, a pair of liquid spray jets mounted on the carriage and connected to a supply of liquid under pressure, an unenclosed turbine wheel positioned so as to be rotated by liquid issuing from the spray jets, and a cable winch driven from a gearbox coupled to the turbine wheel, characterised in that the turbine wheel axis is substantially parallel to the direction of motion of the carriage, and that the spray jets face in opposite directions so as to spray liquid under pressure into respective tunnel-like spaces on each side of the carriage, each such tunnellike space comprising a pair of flexible sheet material curtains which are suspended close to the ground from a framework projecting laterally of the direction of movement of the carriage.

2. Ground spraying apparatus as claimed in Claim 1 wherein the curtains of each pair are separated by a distance such that the impingement of the liquid spray on their inward facing surfaces causes the curtains to close together along their bottom edges.

3. Ground spraying apparatus as claimed in claim 1 or 2 in which the spray jets and the turbine wheel are bodily adjustable relative to each other.

4. Ground spraying apparatus as claimed in any of claims 1 to 3 in which the angular disposition of the spray jets is adjustable.

5. Ground spraying apparatus substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.