GB2120915A - Application device - Google Patents

Abstract

The present invention provides a device for applying a fluid to a locus 12, which device comprises an elongated reservoir 1 for the fluid; means 4 for dispensing the fluid to the locus 12, which means 4 is actuated by contact with the locus; and a retractable shielding means 8 encompassing the dispensing means 4, the shielding means 8 being adapted to be displaced from its shielding position by contact with the locus 12 or matter adjacent to it so as to permit the dispensing means 4 to contact the locus 12. <IMAGE>

Description

SPECIFICATION Application device The present invention relates to a device for applying a fluid to a locus, notably for applying an agrochemical, eg. a herbicide, to weeds.

Many methods are known for applying herbicides to weeds, notably in gardens, but they suffer from a number of disadvantages. Thus, spraying is satisfactory in areas where all the plants are to be treated.

However, due to wind drift and the broad area over which the herbicide is applied, spraying is of no use in treating single weeds among other plants, eg. in a border. It has been proposed to put up herbicides in a wax stick which is wiped over the weed to be treated. Whilst this method enables one to apply the herbicide only to the weed, it is cumbersome to use and the wax hardens with time, making the stick inoperative.

It has also been proposed to fit a rope wick'at the end of a tubular reservoir containing the herbicide solution and to brush the wick across the weed to be treated to apply the herbicide to the weed. However, the rate of release of solution via the wick is erratic, and the pores of the wick are liable to become blocked on contact with the soil. Also there is a risk that the wick will contact other plants due to over vigorous movements of the applicator. Furthermore, wiping of the plant with the wick can be sufficiently vigorous to cause damage to the plant. This can lead to rupture of the cells of the plant, eg. when the stem is broken, and this prevents full transport of the herbicide throughout the plant.This break in trans location of the herbicide can mean that only part of the plant is affected by the herbicide and that the treatment is not fully effective and has to be repeated.

I have now devised a simple device which reduces the above problems and enables a repeatable dose of solution to be applied consistently to a selected locus with reduced risk of physical damage to the plant.

Accordingly, the present invention provides a device for applying a fluid to a locus, which device comprises an elongated reservoir for the fluid; means for dispensing the fluid to the locus which means is actuated by contact with the locus; and a retractable shielding means encompassing the dis pensing means, the shielding means being adapted to be displaced from its shielding position by contact with the locus or matter adjustment to it so as to permit the dispensing means to contact the locus.

For convenience, the device of the invention will be described hereinafter with reference to the prefer red form of the device which is shown in the accompanying drawings in which; Figure 1 is a diagrammatic sectional view of the device in the inoperative position; Figure 2 shows the device of Figure 1 in position upon a plant before the device is pressed downward to retract the shield and bring the dispensing means into contact with the plant; and Figure 3 shows the device of Figures 1 and 2 in the operative position with the dispensing means actuated by contact with the plant.

The invention can be used for the application of a wide range of materials to a wide range of substrates. However, it is of especial use in dispensing aqueous solutions or emulsions of plant treatment chemicals, notably plant growth regulants and/or herbicides, to weeds or other plants growing in the earth and for convenience the invention will be described with respect to that preferred use.

The aqueous solutions or emulsions for present use can be of any suitable strength and can contain any suitable chemical, notably a herbicide of the glyphosate type. Since the amount of fluid which is applied to the plant can be accurately controlled and applied substantially only to the desired locus, it is possible to use more concentrated solutions or emulsions than are safely usable with other forms of dispenser in crowded locations where there is a risk of touching other plants and hence it is necessary to build in a safety margin for mis-application of the fluid. to 1.0 % w/w of active ingredient, as compared to typical strengths of only a few parts per million w/w permitted with spray devices.

The device comprises an elongated reservoir 1 for the fluid to be dispensed. The reservoir 1 is typically generally cylindrical in form and preferably has means, eg. a screw cap 2 and seal 3, at one end whereby the reservoir can be charged with fluid. The cap can provide an airtight seal or a small air bleed can be provided to prevent the build up of an excessive vacuum within the reservoir as the fluid is dispensed. If desired, the end can be provided with a screw thread or other mounting whereby a cartridge of fluid, eg. of herbicide concentrate, can be mounted directly onto the reservoir in place of the cap 3, thus reducing the risk of spillage of the fluid and ensuring that the correct strength of fluid is used for the construction of that particular device.

The reservoir can be of any suitable size and shape, but is conveniently a simple plastics tube with an internal diameter of from 1.5 to 10 cms and a length of from 100 to 150 cms, so as to permit the device to be operated single-handed without stooping.

The other, open end of the reservoir is provided with the means for dispensing the fluid. The dispensing means is actuated by contact with the locus, eg.

the weed, to be treated, notably by the pressure of the contact between the device and the locus. Thus, the dispensing means can take the form of a spring loaded valve which is opened as the device is pressed against the weed; or it can take the form of a flexible membrane having an aperture therein which is normally closed but which can be splayed as the device is pressed against the locus.

A particularly preferred form of dispenser comprises a compressible porous sponge-like member 4 into which fluid from the reservoir soaks and which exudes that fluid onto the locus as the sponge is compressed against the locus as shown in Figure 3.

Such a dispensing means is very simple and also dispenses a substantially consistent amount of fluid each time it is compressed. Furthermore, since the pressure required to compress the sponge is small, little or no physical damage is done to the cell structure of the plant to be treated. Typically, member 4 is of such a construction and size that it will release from 0.025 to 1 ccs of fluid when it is compressed to reduce its volume by from 50 to 90% of its original volume and will recharge with fluid in from 0.5 to 2 seconds. Typically, member 4 is made from an open cell polymeric foam having a bulk density of from 20 to 35 Kgs per m3 and which recovers to substantially its original volume after compression within 2 seconds. The optimum sponge or foam material for any given case can be determined by simple trial and error tests.

The sponge-like member 4 preferably takes the form of a cylindrical pad of an open pored waterwettable cellular natural or synthetic resin material, eg. a foamed polyurethane, polyether, polyethylene or polyvinylic resin. This pad is mounted, eg. by adhesive, in or upon the open end of the reservoir and is in fluid flow communication with the reservoir. Preferably, the pad is mounted removably on the reservoir, eg. by being a push fit into the open end of reservoir 1 or a socket mounted thereon, so thatthe member 4 can be removed for cleaning or can be reversed to prolong the operating life of the pad. It will be appreciated that where part of the sponge is housed within a rigid housing, that part of the sponge within the housing will not be compressed upon contract with the locus.The dosage of fluid applied at each actuation of the device can be varied by varying the volume of the sponge which is available to be compressed.

Where a comparatively coarse pored pad is used, the fluid in the reservoir may seep through the pad at an excessive rate. It is therefore preferred to provide a flow restriction to the outflow of fluid from the reservoir upstream of member 4. This restriction conveniently takes the form of a transverse wall 5 at oradjacentthe open end of the reservoir, having a small bore or aperture 6 therethrough to permit passage of fluid from the reservoir to the pad.

Alternatively, the reservoir can have an internal plug flow restrictor; or the open end of the reservoir can be sealed with a transverse rubber or plastics membrane which is pierced when a demountable pad is affixed to the reservoir, the rupture in the membrane acting as the flow restriction. The optimum size of the aperture or bore to achieve wetting of the pad to give the desired application rate of fluid without excessive dripping of fluid from the pad will depend upon, inter alia, the viscosity of the liquid being dispensed and the nature of the material from which the pad is made. However, the optimum cross-sectional area for the aperture or bore 6 will usually lie within the range 0.05 to 20 square mms, corresponding to aperture diameters in the range 0.25 to Smms, eg. 0.75 to 2.0 mms.The optimum aperture can be readily determined for each case by simple trial and error, in general the more viscous the fliud to be dispensed, the larger the aperture required to achieve a given rate of application.

Preferably, there is a fiiter upstream of restrictor 5 to reduce the risk of blockage. Conveniently, such a filter is provided by a second pad 7 of cellular natural or synthetic resin situated within reservoir 1 above restrictor 5. Preferably, the second pad 7 is made from the same material as member 4. If desired, the lower face of member 4 can be covered with a coarser pad to reduce the risk of blockage of member 4 due to contact with the ground.

As stated above, the device is provided with a shielding means which serves to reduce the risk of contacting wanted plants with the dispensing means during transport of the device from one locus to another and during placement of the dispensing end of the device upon a plant to be treated. The shielding means is moveable by contact with the locus or with ground or other material adjacent to the locus between an operative position and an inoperative position, at which latter the dispensing means has been placed into contact with the locus.

Thus, the shielding means can take the form of a pivotted guard plate which is swung aside as the device is pressed against the locus. However, a particularly preferred form of shield comprises a sleeve 8 which is slideably journalled substantially co-axially on the dispenser end of reservoir 1. The sleeve 8 is adapted to move axially with respect to the reservoir upon contact with the locus and thus permit the device to move axially further towards the locus so as to bring the member 4 into contact with the locus and then to compress member 4 to release the fluid which it carries. In its rest position, the sleeve extends axially at least to the free end of the dispensing means, and preferably 0.5 to 7.5 cms beyond, so that the dispensing means is radially encompassed by the sleeve.Preferably, the sleeve 8 is biassed, eg. by means of a spring 9 acting against a stop 10 on the reservoir and a shoulder 11 within the sleeve 8, into the operative downwardly extending shielding position.

In operation, the reservoir 1 is charged with suitable fluid, eg, by pouring water and the requisite amount of a powder or fluid concentrate into the reservoir via the capped end of the reservoir for mixing in situ. However, it is preferred to mount a container of premixed concentrate upon the capped end of the reservoir in place of cap 2 as described above. After charging, the reservoir is closed, eg. by screwing home the cap 2 or leaving the container mounted in place of cap 2 to seal the reservoir. The sealing of the reservoir causes a vacuum to be drawn within the reservoir as fluid is dispensed and this prevents excessive fluid flow through the member 4.

The filied device can now be carried to the desired site of use with the sleeve 8 preventing member 4 from touching plants until the sleeve 8 is contacted with the ground as the device is placed upon the target weed or other locus and depressed to bring member 4 into contact with that plant or weed. It is thus possible to poke the device around under a bush to locate and treat weeds under that bush. The dispensing end of the device is pressed against the target weed 12 or other locus to cause the sleeve 6 to move axially up the reservoir and thus allow the member4to be moved onto the target weed and then be actuated upon that weed. With sponge-like members for the dispensing means 4, a substantially consistent amount of fluid is dispensed at each actuation and at the desired locus. The device of the invention is thus economical in the amount of active ingredient used and achieves application of the fluid therein at substantially only the desired locus.

Furthermore, I have found that a sponge-like dispensing means is surprisingly rapidly recharged with fluid after each actuation. It is therefore possible to achieve a more rapid series of applications, e.g. 60 to 100 per minute, than might have been considered possible.

Whilst the device has been described in terms of an elongated reservoir which carries all the other components and which acts as the handle by which the device is carried this need not be the case and the reservoir and other components can be separate and mounted on a suitable carrying frame.

Claims (10)

CLAIMS:

1. A device for applying a fluid to a locus 12 characterised in that the device comprises an elongated reservoir 1 for the fluid; means 4 for dispensing the fluid to the locus 12, which means 4 is actuated by contact with the locus; and a retractable shielding means 8 encompassing the dispensing means 4, the shielding means 8 being adapted to be displaced from its shielding position by contact with the locus 12 or matter adjacent to it so as to permit the dispensing means 4 to contact the locus 12.

2. A device as claimed in claim 1 characterisedin that there is provided a flow restriction 5 to the outflow of fluid from the reservoir 1 to the dispensing means 4.

3. A device as claimed in claim 2 characterisedin that the flow restriction 5 comprises a member having an aperture or bore 6 therethrough having a cross-sectional area of from 0.025 to 20 square mms, which member is located at or adjacent the outlet from the reservoir 1.

4. A device as claimed in any of the preceding claims characterised in that the dispensing means 4 comprises a compressible sponge-like member in fluid flow communication with the reservoir 1 and adapted to release fluid by compression of the member 4 upon the locus 12.

5. A device as claimed in claim 1 characterisedin that dispensing means 4 comprises a cellular natural or synthetic resin member removably mounted at or adjacent the end of the reservoir 1.

6. A device as claimed in claim 1 characterisedin that the shielding means 8 comprises a sleeve member slideably mounted substantially co-axially upon the dispensing end of the device for axial reciprocation from a shielding position in which it encompasses the dispensing means 4 to a retracted position in which the dispensing means 4 can contact the locus 12.

7. A device for the application of an aqueous solution or emulsion of an agrochemical to a locus 12 which device is characterised in that it comprises a substantially tubular reservoir 1 having one end closed by means of a detachable cap member 2 so as to permit charging of the reservoir 1 with fluid to be dispensed; the other end of the reservoir 1 being provided with a sponge-like dispensing member 4 in fluid flow communication with the reservoir 1 by means of a flow restriction means 5 whereby the sponge-like member 4 can take up fluid from the reservoir 1 and upon compression of the member4 against the locus 12 can discharge fluid onto the locus 12; that end of the device also being provided with a sleeve member 8 journalled substantially co-axially upon the reservoir 1 for axial reciprocation with respect to the reservoir 1 by contact with the locus 12 or its surrounds from a first position in which it radially encompasses and projects axially beyond the sponge-like member 4 to a second position in which the sponge-like member 4 can contact the locus 12 and be compressed against the locus.

8. A device as claimed in claim 7 characterised in that the sponge-like member 4 comprises a generally cylindrical member of a cellular natural or synthetic resin material which is a removable push fit mount upon the end of a tubular reservoir 1 and the flow restriction is achieved by an aperture 6 having a diameter of from 0.75 to 2.0 mms in a transverse member 5 at or adjacent the end of the reservoir.

9. A device as claimed in claim 1 characterisedin that the dispensing means 4 comprises a foamed plastics member which will release from 0.025 to 1 cc of fluid when compressed into from 50 to 10% of its original volume.

10. A device as claimed in claim 1 characterised in that the cap member is provided by a container for the fluid to be dispensed mounted upon the reservoir.