GB2078550A - Spraying Apparatus - Google Patents

Abstract

A spraying head comprises a pair of hollow concentric cones 31 and 32, the outer cone 32 being rotatable and open at its periphery 38, the inner cone having an aperture 33 at its apex, a shaft 35 concentric with the cones and passing through the inner cone and its aperture, the shaft being rotatable with the outer cone 32. The shaft 35 is mounted in a bearing 41 which is on the side of the aperture 33 remote from the apex of the outer cone. In operation, the inner cone is stationary and the outer cone is rotated by a drive 36 applied to the shaft 35, and liquid fed from 34 to the interior of the inner cone drips through the aperture 33 to the interior of the outer cone and is then flung in atomised drops from the periphery of the outer cone. The shaft is rotated by pulley and belt drive 43, 44. <IMAGE>

Description

SPECIFICATION Spraying Apparatus This invention relates to apparatus for spraying fields or crops with a liquid solution. Conventional apparatus comprises a container for the solution, 9 spraying head and a pump for pumpng liquid from the container through the spraying head. The conventional apparatus is usually transported by a tractor and is provided with means for attachment to the three-point linkage of the tractor. Some conventional devices are provided with a plurality of spraying heads mounted on booms which extend on either side of the tractor and are usually hingeable to lie along the direction of travel when not in use and being transported in restricted areas.The spraying heads have to withstand dirty conditions when in operation in the field, and particularly the heads towards the end of the booms have to be able to withstand shocks caused by the boom hitting the ground as the tractor rocks on the field.

The conventional spraying head atomises the solution into fine droplets. If the range of droplet size is large, the majority of the volume of the solution will be emitted in the large droplets, since the volume of the droplets is proportional to the cube of the diameter. Large droplets are less effective in connection with the crop spraying since the large droplets tend to bounce off the crops or at least quickly run down the crop leaf to fall on the ground. In order to guarantee sufficient absorption of the solution by the crops, it is necessary to waste a large amount of the solution in the form of the larger ineffective droplets. This means that the sprayer must use a large container or must return to refill the container at frequent intervals.

Each of the plurality of spraying heads emits droplets in a hollow cone or a fan aligned parallel to the boom, and the heads are positioned on the boom and the boom located in relation to the ground so that the hollow cones or the ends of the fans from alternate heads touch at ground level. If the boom is mounted a long distance from the tractor wheels, pitching of the tractor will vary the height of the boom above the ground and will therefore vary the distribution of the droplets over the ground since the cones or fans will have a smaller spread when the boom drops towards the ground and a greater spread when it lifts away from the ground. If the boom is rigidly mounted in relation to the tractor, rolling of the tractor will also vary the height of the spraying heads above the ground, and the end spraying heads may even strike the ground.

According to one aspect of the invention there is provided a spraying head comprising a pair of concentric hollow cones, the outer cone being rotatable and being open at its periphery, the inner cone having an aperture at its apex, a shaft concentric with the cones and passing through the inner cone and its aperture, the shaft being rotatable with the outer cone, a bearing for the shaft on the side of the aperture remote from the apex of the outer cone and means to feed liquid to the interior of the inner cone, the arrangement being such that when the cones are inverted and the inner cone is stationary and the outer cone is rotating, liquid can drip from the inner cone to the interior of the outer cone and then be flung in atomised drops from the periphery of the outer cone. The periphery of the outer cone is preferably provided with radial grooves to assist atomisation.

According to another aspect of the invention there is provided spraying apparatus comprising a platform adapted to support a container of spraying solution, a frame including guides for guiding the platform up and down, means for moving the platform in the guides, a spraying head and means to force solution from a container supported on the platform to the head.

The head is preferably mounted on the platform for movement therewith, and the head is preferably mounted on the boom located betweeen the guides and the operational position of the container on the platform. The platform can be moved to one position on the guides for loading a container thereon, and is then raised to a second position for the spraying operation.

When the spraying head is mounted on the platform, the second position is selected so that the spraying head is the correct height above the articles to be sprayed.

According to another aspect of the invention there is provided a mechanical drive connection between the motor and a plurality of drive outputs, the connection comprising an input shaft driveable by the motor, a plurality of driving pulleys mounted for rotation with the input shaft, a plurality of driven pulleys aligned with respective driving pulleys, belts connecting respective aligned pulleys to impart a drive between them and a plurality of shafts connected to respective driven pulleys to provide said drive outputs. The plurality of shafts preferably comprise or are connected to a plurality of flexible cables, and the belts preferably comprise O-rings.

A speed measuring device may be provided to measure the speed of rotation of the input shaft.

An example of the invention will now be described with referance to the accompanying drawings, in which: Figure 1 is a schematic diagram of a spraying device, showing the booms and spraying heads in operational position, but with other parts of the apparatus removed, Figure 2 is a perspective view of the main boom and its mounting relative to the platform in the apparatus of Figure 1, Figure 3 is a detail of a boom hinge of Figure 2, Figure 4 is a schematic diagram of the platform without the boom and its spraying heads, but showing a single spraying head and also showing the container about to be loaded on the platform, Figure 5 is a section through a spraying head and, Figure 6 is a diagram of a cable drive distribution box.

The spraying device illustrated in the drawings comprises a frame 11 provided with conventional brackets (not shown) for attachment to the threepoint linkage of a tractor (also not shown). The device is intended to be mounted at the rear end of the tractor, and the view in Figure 1 is from the side of the device remote from the operational position of the tractor. The frame 11 is formed with vertical guides 1 2 and a fork lift platform 1 3 mounted for movement up and down the guides 12.The platform 13 has a fork including a pair of arms 14 for engagement with a conventional pallet on which is mounted a container for the spraying solution, or special containers such as that illustrated at 1 5 in Figure 4 may be provided with rectangular section channels 1 6 on their underside for engagement with the arms 14 of the platform 13.

A main boom 21 is mounted on the platform 1 3 between the guides 12 and the operational position of the container 15. The boom 21 comprises a central section 22 containing no spraying heads and a pair of opposite end sections 23, 24 hingedly connected to the central section and each containing four spraying heads 25 uniformly distributed along the section. The end sections 23, 24 hinge forwardly or backwardly when not in use to lie parallel to the arms 14 to allow passage through gateways and along roads. A rear boom 26 is provided with two spraying heads 25 which fill the gap between the heads on the main boom 21 to give a uniform coverage of the ground between the outer ends of the main boom 21.The rear boom 26 is hingedly mounted to the central section 22 and is provided with the necessary mechanical, electrical and fluid connections thereto as will be described later. The rearboom 26 is hinged upwards to clear the container 1 5 so that is does not obstruct loading and unloading of the container 15 from the arms 14.

For different applications, a single spraying head 27 (Figure 4), such as is described in British Patent Specification No. 1,590,650, is provided on an articulated spraying arm 28. This single head 27 can be provided as an alternative to the main and subsidiary booms 21 and 26 if desired.

The apparatus so far described differs from the conventional spraying apparatus in that the container 1 5 is not permanently included in the device. Instead, the device is used in conjunction with a supply of containers on pallets from a central station. The fork lift arrangement on the device is used to collect a container full of spraying solution from the central station. The container is provided with an outlet pipe which extends to the bottom of the container and an inlet pipe opening into the top of the container.

The device includes conduits which connect these pipes to a pump, and the pump outlet is also connected to the spraying head or heads through flow control apparatus to be described. The pipes and associated apparatus are conventional, and are not illustrated in the present drawings. Details of such apparatus can be obtained from the above-noted British Patent Specification.

When the spraying device is to be operated, the platform 13 is raised by an hydraulic ram 17 to the desired height in the guides 12, so that the spraying head or heads 25, 27 are at the height above the ground appropriate to the desired spraying pattern. If the single additional head'27 is provided, the extension of its arm 28 is adjusted to direct the outlet of the additional head 27 at the right height and direction. This arm 28 is similarly adjusted hydraulically.

The construction of a head 25 will now be described with reference to Figure 5. Essentially, the head 25 comprises two hollow inverted cones 31,32. The inner cone 31 is stationary, and has a hole 33 at its apex. The inner cone 31 is mounted from a supporting plate 42 by four legs 45 extending to its interior conical surface. The solution to be atomised is supplied to the interior of the cone by a pipe 34, running down the interior surface of the cone 31 to drop through the apex aperture 33. The outer cone 32 is mounted on a central shaft 35 and is rotated at a controlled speed by a drive applied to its upper end. The cones 31,32 have out-turned lips 37, 38 which are closely spaced. Drops of solution from the inner cone travel up grooves on the interior surface of the outer cone 32 by centrifugal force to reach the upper lip 38 of the outer cone which is also radially grooved.The speed of rotation of the outer cone, the flow rate of liquid and the shape of the cone determine the average size and the range of sizes of the atomised drops. The outer cone 32 has an axial stem 40 in which a bolt 39 is located.

As shown the outer cone 32 is rotated with shaft 35 by a belt drive 44 applied to the disc 43 which is a pulley. The belt 44 is drive by one of two pulleys not shown on a common shaft driven by a cable drive 36 from a distribution box described below. The two pulleys not shown are of different sizes so that the head can be driven at two different speeds. In an alternative drive arrangement the cable drive 36 is applied directly to the top end of the shaft 35.

Problems arise with the mounting of the outer cone 32 for rotation about the inner cone 31.

Earlier heads have been designed with the central shaft forming an extended spindle of an electrical motor but electrical motors have been found not suitable for the rigorous conditions encountered in crop spraying work. Another design has the central shaft stationary, with the outer cone mounted on bearings at the top and bottom of the shaft. It has been found, however, that the solution destroys the lubrication of the lower bearing so that after periods of disuse the outer cone is either jammed solid or at best rotates at a different speed from the design speed. The present atomising heads ar? therefore designed with the central shaft 35 fixedly connected to the outer cone 32 at its apex, the shaft being mounted in the bearing 41 at the upper end of the head.In either drive arrangement the disc 43 serves to protect the bearing 41 from the solution to be atomised. Although most of the solution tends to flow through the aperture 33 and up the interior of the cone 32, some solution creeps up the central stem of the cone 32 and will cause damage to the bearing 41, particularly if it remains in the bearing at rest. The disc 43 on the stem 40 will cause solution creeping up the stem 40 to be flung off from the rim of the disc 43 as the system is rotated. It would be difficuit for solution to creep radially inward over the top surface of the disc 43 while the system is being rotated, so the bearing is protected.

A separate drive 36 is provided for each head.

The flexible cable drives 36 are all driven from a distribution box from a common drive spindle as illustrated in Figure 6. Figure 6 illustrates a hydraulic variable speed motor 51 driving the drive spindle 52, but the spindle 52 may be driven by the mechanical power take-off of the tractor, or by an electric motor, asis conventient. The drive spindle 52 is provided with ten pulleys 53 along its length, the pulleys 53 being mounted for rotation with the spindle. Ten driven pulleys 54 are arranged in different radial directions around the central spindle 52, the driven pulleys 54 being aligned with respective driving pulleys 53 on the driving spindle 51. 0-rings 55 pass around respective pairs of driving and driven pulleys. The flexible cable drive 36 to the spraying heads are connected for rotation with the driven pulleys.

The speed of rotation of the central spindle is measured by a proximity counter 56 sensing the position of a radial lug 57 on the spindle, to assist the operator in his control of the speed of the drive to the spindle 51 and hence to the individual spraying heads 25. The speed control is achieved by altering the oil flow if an hydraulic motor is used or by altering the supply if an electric motor is used. It is normally intended that all the heads 25 shall rotate at the same speed, all the pulley ratios (53:54) being the same but different speeds can be achieved by substituting different pulleys. The O-rings 55 and the flexible cables 36 have been selected to accommodate any shock received by the spraying heads 25, for example if the head momentarily touches the ground which suddenly increases its resistance to rotation.

The supply of solution to the spraying heads is fed from the container through a pump connected to the outlet pipe of the container and distributed through hoses to the individual spraying heads.

The pump, which can be driven in any of the ways suggested for the drive to the central spindle for the spraying heads, also has its pressure controlled by the operator. The rate of flow to each head can be varied by altering the pressure and a replaceable restrictor connection to the conduit near each head. Such restrictors are usually colour coded for different cross sections.

A solenoid-operated valve is placed in the conduit near the spraying head so that the operator can cut off the supply of solution to the head when spraying stops. The small volume between the valve and the head reduces the amount of solution which is left to drip into the head when it has stopped rotating. The solution from such a dead volume may form a deposit in the head, affecting future performance, and must therefore be kept to a minimum. The operator can close the valves before stopping the drive to the heads so that most of the solution from the dead volume is converted into atomised drops and does not remain within the head.

The present device enables a very close control to be made of the droplet size emitted. Whereas previous devices have been found to produce a wide range of droplet volumes, such that the ratio of the volume mean diameter to the number mean diameter has been as great as sixteen, the corresponding ration for the present head has been found to be as low as 1.1. The volume mean diameter is the diameter which represents the droplet size at which the majority of the volume of spray in the container is emitted, whereas the number mean diameter is simply the average diameter of all the droplets emitted.The volume of solution required to treat a given area is drastically reduced because a low volume mean diameter/number mean diameter ratio means that all the solution is emitted in the required droplet size, therefore avoiding unnecessary production of drops that are regarded as too small or too large. Previously, ready-mixed solutions have not been practical in view of the large volumes required. The present apparatus can be used with ready-mixed solutions, and it is for this reason that the lifting platform is provided so that the tractor with the apparatus attached can be arranged to pick up containers of ready-mixed solution on pallets without any delay and with much improved safety and reduced chance of error which would be encountered if the operator had to stop to mix certain powders in given proportions and add a measured volume of water, probably through a slow-flowing hose.The ready-mixed solution can be accurately controlled by the manufacturer and conveniently delivered to the farm.

The mounting of the main boom forward of the container is as close as practicable to the front of the apparatus and thus as near as possible to the back axle of the tractor. This minimum distance between the boom and the back axle reduces the effect of pitching of the tractor so that the spraying pattern of the heads on the main boom is only minimally affected by pitching of the tractor over rough ground. The main boom may be mounted on the platform by a gimbal arrangement which compensates for pitching and rolling of the tractor, keeping the main boom parallel to the average position of the back axle.

The main boom should not be kept horizontal by this arrangement, since it would not then be possible to keep the heads on the main boom a controlled height above transverse scans of a sloping field.

Figure 2 illustrates the gimbal mounting of the boom 21. A plate 61 attached vertically to the central section 22 is connected to the platform 13 by parallel links 62 which move in a vertical plane.

Rigid trapezium links 63 support the boom 21 against excessive downward pivoting of the links 62 (e.g. when the tractor pitches) and also against pivoting of the boom about a horizontal axis along the line of tractor travel (e.g. when the tractor rolls). Air dampers 64 are provided between the platform 13 and the central section 22 and reduce whipping of the boom (i.e. rotating about a central vertical axis).

Figure 3 is a detail of the hinges to the boom 21 of Figure 2. The hinge is a double hinge, including a link 65 hinged at one end 66 to the central section 22 and at the other end 67 to an end portion 23 or 24. Springs 68 on both sides of the hinge urge the boom to its operational position.

The spraying heads 25 may be improved by applying a high voltage (of the order of 30kV) by a needle eiectrode adjacent the pipe 34. The high voltage can be generated from the tractor supply.

Claims (1)

1. Claims

   1. A spraying head comprising a pair of concentric hollow cones, the outer cone being rotatable and being open at its periphery, the inner cone having an aperture at its apex, a shaft concentric with the cones and passing through the inner cone and its aperture, the shaft being rotatable with the outer cone, a bearing for the shaft on the side of the aperture remote from the apex of the outer cone and means to feed liquid to the interior of the inner cone, the arrangement being such that when the cones are inverted and the inner cone is stationary and the outer cone is rotating, liquid can drip from the inner cone to the interior of the outer cone and then be flung in atomised drops from the periphery of the outer cone.

   2. A head as claimed in claim 1 wherein the periphery of the outer cone is formed with radial grooves on the side facing the inner cone to assist atomisation.

   3. A head as claimed in claim 1 or claim 2 comprising a disc on said shaft between the outer cone and the bearing.

   4. A head as claimed in claim 3 wherein said disc is a pulley forming part of a drive connection for rotating said shaft and outer cone.

   5. A head as claimed in any one of claims 1 to 3 comprising a cable drive connected to said shaft for rotating said shaft and outer cone.

   6. A head as claimed in any one of claims 1 to 5 comprising a stationary plate for supporting said bearing, said inner cone being supported from said plate by a plurality of legs.

   7. Spraying apparatus comprising a platform adapted to support a container of spraying solution, a frame including guides for guiding the platform up and down, means for moving the' platform in the guides, a spraying head and means to force solution from a container supported on the platform to the head.

   8. Apparatus as claimed in claim 7 wherein the head is mounted on the platform for movement therewith.

   9. Apparatus as claimed in claim 7 or claim 8 wherein the head is mounted on the boom located between the guides and the operational position of the container on the platform.

   10. A mechanical drive connection between the motor anda plurality of drive outputs, the connection comprising an input shaft driveable by the motor, a plurality of driving pulleys mounted for rotation with the input shaft, a plurality of driven pulleys aligned with respective driving pulleys, belts connecting respective aligned pulleys to impart a drive between them and a plurality of shafts connected to respective driven pulleys to provide said drive outputs.

   11. A connection as claimed in claim 10 wherein the plurality of shafts comprise or are connected to a plurality of flexible cables, and the belts preferably comprise O-rings.

   12. A connection as claimed in claim 10 or claim 11 comprising a speed measuring device to measure the speed of rotation of the input shaft.

   New Claims or Amendments to Claims filed on 9 Sept 1981.

   Superseded Claim 1.

   New or Amended Claims:

   1. A spraying head comprising a pair of concentric hollow cones, the outer cone being rotatable and being open at its periphery, the inner cone having an aperture at its apex, a shaft concentric with the cones and passing through the inner cone and its aperture, the shaft being rotatable with the outer cone, the shaft only having a wearing on the side of the aperture remote from the apex of the outer cone, and means to feed liquid to the interior of the inner cone, the arrangement being such that when the cones are inverted and the inner cone is stationary and the outer cone is rotating, liquid can drip from the inner cone to the interior of the outer cone and then be flung in atomised drops from the periphery of the outer cone.