GB2278988A - Apparatus and method to control the growth and spread of plant vegetation - Google Patents

Abstract

A flow of air is generated by a motor-powered device, the air in the flow being heated directly or indirectly and the heated air being directed at plant vegetation to be killed. The apparatus shown comprises a handle 1, a shaft 2, a motor 16, an electric heater 17 and an outlet nozzle 5, and or an application head 6, which can be attached to the outlet, from which the heated air is directed at the plant vegetation. Figure 2 shows an electric circuit and Figure 3 shows a range of application heads which may incorporate a trident (27) or rake (28). Numerous embodiments are disclosed in the specification e.g. the apparatus may be mounted on wheels or be of 'hover' type. <IMAGE>

Description

Apparatus and Method to Control the Growth and Spread of Plant Vegetation This invention relates to a horticultural device to control, inhibit and destroy plant vegetation and aid weed control in gardens, other horticultural areas such as parklands and walkways.

It has been noted from early times that plant vegetation can be destroyed by fire. Today this practice is used on a large scale to clear forests and to remove unwanted crops or crop remains by farmers after harvesting. On a smaller scale, specialised flame guns using pressurised gas or flammable liquids have been used. These are operated by igniting the pressured flammable material and burning the vegetation with the flame. More recently, chemicals have been used to selectively destroy unwanted plant vegetation. These can be applied in solid, liquid or vapour form either directly to the plant or to the ground to be cleared. The more traditional method of controlling unwanted plant growth, in particular "garden weeds" has been performed manually by forking, raking and hoeing the ground to remove, dislodge or expose the plant's roots to sunlight in order to kill the plant.This can be, however, very labour intensive.

An aspect of all keen gardeners and horticulturalists is to select only the plants which they want to grow, either for their decorative and appealing features such as flowers, or consumption such as vegetables. In either case it is advantageous if the "weeds" around the plants are inhibited from growing so that they do not compete with the selected plants. Such competition can detract from the appearance of the "flower", reduce crop output of the vegetable, encourage garden nuisance animals such as slugs or even kill the plant.

Recent environmental legislation will ban farmers from using fire to remove plant vegetation. The application of flame guns is limited to large area clearance because of the difficulty of controlling the flame itself. In addition such guns can be dangerous to both person and property, they are energy intensive and environmentally unfriendly. Although improvements have been made to chemical formulations to control plant growth, plant selection is usually limited to "broad leaf plants" and "thin leaf plants". Use of some chemicals have been associated with health related problems; some chemicals can have an inhibitory effect on future plant growth, re-seeding and the time delay before re-seeding can commence; cause ecological imbalances to plant and animal life and may require specialised methods of application such as protective clothing or measured dose rates.

It is an object of this invention to provide an apparatus and method to control the growth and spread of plant vegetation.

According to the present invention there is provided a method of controlling the growth and spread of plant vegetation in which air may be drawn or blown into a chamber by a motor, heated and expelled through a nozzle which is directed at the plant vegetation to be killed. The term "weed" is used herein to refer to unwanted plant vegetation.

All living organisms (plants and animals) of which weeds are a part, have a temperature tolerance at which they can survive, although this tolerance varies between species, in general temperatures in excess of 80 celsius will have a denaturing effect on the organism's metabolism. Such a denaturing effect ultimately causes the organism's death. We have found that exposing weeds to hot air for a short period of time or until the weed wilts, provides a safe and controlled mechanism to control the growth and spread of weeds and ultimately the death of the weed.

The method will usually involve drawing air through a grille or may be a filter, these may be integral with the air intake motor or blower and or heater or may be remote from them. The air intake motor or blower and heater may be operated from an external mains electricity supply, usually 240 / 100 volts, or future derivatives of the invention may be powered from an attached or remote power generator. The air may be heated by means of an electric filament or similar electric heating device and expelled through a nozzle. The nozzle may be designed so that a range of application head attachments may be secured to it. In some applications an application head may not be required.The various head attachments may be used to direct, concentrate or disperse the hot air, act as a shield to protect neighbouring plants, have a rake, trident or hoe design to allow mechanical agitation of the soil as an aid to the hot air process.

The invention may initially consist of a single motor unit housing comprising of a heater and air intake motor on a shaft with a handle. The invention will be held and the various methods of employment will be; to direct the nozzle with the various application heads at the weeds and to "work" the head in various patterns to cover an area of ground; to use the mechanical rake or hoe type attachments to rake, agitate or loosen weeds in conjunction with the hot air process. Future applications may consist of a wheeled version which could be pushed or pulled over the ground, a "hover" type system and versions and combinations of the above which may have a plurity of heater and air intake motors and or blowers.

According to the present invention there is also provided an apparatus for controlling the growth and spread of plant vegetation, comprising of a handle with an on/off trigger switch and may be a safety lock-on switch, this may be integral with the handle or trigger. The handle will also have an electrical connection or electrical lead or socket to connect to an external electrical power supply and may be an integral electrical fuse. An auxiliary handle may also be included and positioned along the shaft of the invention, such an inclusion may reduce muscular strain during prolonged use and aid control and comfort. Air may be drawn into the invention by an air intake motor. In some applications it may be advantageous to use an air blower.It may be advantageous to the operation of the invention to have the air intake grille above the air intake motor and heater so that cold air may be drawn into the invention. It may also be advantageous to have an air filter on the air intake so that dust and debris may be prevented from entering the heater and burning internally. The air intake motor and heater may be integral in one unit with the heater preceding the air motor or vice versa or the units may be separated. The heater and air motor may be in-line, tangential or at some other angle to one another.

Although it will be beneficial to have the heater and air motors at the base of the invention, they may be placed anywhere between the handle and the end nozzle. The nozzle may be designed so that a range of application heads may be pushed, screwed, pinned or secured to it. The use of the application heads may allow hot air to be focused, diffused, directed or spread over the weeds, allow protection to other vegetation and provide a mechanical rake and hoe mechanism to dislodge, agitate and expose weeds and the roots to the hot air process.A further inclusion to both the nozzle and the application heads may include treatment with heat sensitive paint, or a similar thermal indicator device, so that the colouration of the head or indicator may be indicative of its temperature, also an application tool to allow fitting and removal of heads during use or a collar locking mechanism made of thermotolerant material to hold and lock the application head to the nozzle and allow fitting and removal when the application head is hot. It may be advantageous in some applications not to have the application head attached to the nozzle in instances where a general sweep of the ground may be more appropriate. It may also be a future modification that the design of the nozzle may not require an application head.

A further inclusion to the invention may be a moveable joint between either the application heads, nozzle, heater motor, air intake motor and handle or combination of these to provide both left and right rotation and up and down movement such that the hot air can be directed in a certain direction or the invention can be held more comfortably. A further inclusion may be a temperature controller so that the heat output can be controlled during use, such an inclusion would be advantageous to the husbandry of young plants. A thermocouple sensor or similar temperature monitoring device may be housed in the nozzle, heater or may be application head, would detect the hot air temperature and signal it back to a temperature controller housed in the body of the invention.If the air temperature was higher than that required, less heat would be produced by the heater, if the temperature was lower then the heater element would increase power output. Future applications may consist of a wheeled version which may be pulled pushed or self powered over the ground displaying a single wheel or a number of wheels; a "hover" type system whereby the down draught from the hot air provides a "floating" platform or a system with a combination and plurity of heaters, nozzles and air in-take motors or air blowers in combination with a hand held, wheeled or hover type applications.

Certain embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1. is a schematic representation of an apparatus for controlling the growth and spread of plant vegetation, Figure 2. is a schematic outline of the circuit diagram, Figure 3. is a range of diagrams illustrating the application heads.

The apparatus shown in Figure 1 may be used for controlling the growth and spread of plant vegetation (weeds) and comprises of a handle 1, a shaft 2, an auxiliary handle 3, a motor unit housing 4, an outlet nozzle 5 and an application head 6.

In this example the handle 1 comprises of an electrical mains connector 8 and connector socket 7, a fuse box 9, a safety lock-on switch 10, an on/off trigger 11 and a temperature regulator 13. For basic operation the invention can be used using only items 8,7 and 11 on the handle. The positions of items 7,9,10,11 and 13 may be different from those illustrated in the diagram, as well as the future shape and design of the handle may vary and may have a hand-guard 12.

In this example the shaft 2 has been shown as a discrete item connecting the handle 1 and the motor unit housing 4. The shaft may also be an integral part of the handle and motor unit if a moulding process or similar is used for manufacture.

It may also be the case that the end of the shaft may be the nozzle, out of which the hot air is expelled, and that provision is made on the shaft to incorporate the air intake grille 15, air intake motor 16 and electric heater 17. In this example an auxiliary handle 3, if required, may be positioned along the length of the shaft, rotated about the shaft and tilted forwards or backwards by loosening and tightening the locating pin 14. In future, the auxiliary handle may be an integral moulding of the handle 1, shaft 2 and motor head housing 4, performed during the manufacture process.

The motor head housing 4, in this example, comprises of an air intake grille 15, an electronic temperature controller 29, an air intake motor 16, an electric heater 17 and a circuit board 22. In this illustration these items (except 22) have been shown in series though their positions relative to one another and to the motor unit housing may be different.

The air intake grille may also incorporate or may be replaced by an air filter (not shown). In operation ambient air may be drawn in through the air intake grille by means of the electric intake motor, the air may be heated by the electric heater and displaced through the nozzle. Units 15, 16, 17 and 5 may be an integral unit or may be separate or a combination thereof. If separate, a manifold pipe (not shown), may connect each unit to one another and or combinations of units 15, 16, 17 and 5.

The nozzle 5, in this example is integral with the electric heater 17, although it may also be a separate item.

A temperature sensor 19 may be integral or attached to either the interior or exterior of the nozzle to monitor the temperature of the hot air being produced by the invention.

The signal from the temperature signal may be relayed to the electric temperature controller 29, preferably housed in motor unit housing 4. The end of the nozzle in this example is recessed to accommodate the push-on fit of an application head 6. Future fastenings may include screw fit, pin locator or similar or a collar fastening mechanism preferably made of thermotolerant material. It may be advantageous for items 5 and 6 to be coated with thermal indicator paint or similar or some other device which would indicate the temperature of these items when they are in use. It may also be the case that in some applications that the application head may not be required during use or that the design of the nozzle will not require application heads to be attached to it.A moveable joint may also be included to allow the motor head unit 4 and or the nozzle 5 with the application head 6 to rotate or tilt about the shaft (not shown).

Referring now to Figure 2, a schematic outline of the circuit diagram illustrates how the invention may operate.

Electrical power to the invention may be via the electrical connector 8, a suitably rated in-line fuse 9 may be included as well as a safety-on switch 10 which may operate an electrical relay switch 20 within the circuit. On/off operation of the invention may be via a trigger or switch 11, which may operate a circuit relay switch 21. It would be preferable but not essential that 9, 10, 11, 20 and 21 are housed in the handle 1. In this example, power distribution to the air intake motor 16, electric heater 17 and electric temperature controller 29 may be via a circuit board 22 housed in the motor unit housing 4, but may be housed in the shaft 2 or the handle 1. In this example power may be supplied from the circuit board direct to the electric air intake motor 16 and to the electric temperature controller 29. The electric temperature controller receives the operating temperature requirement from the temperature regulator 13 and actual operating hot air temperature from the temperature sensor 19 in the nozzle, from which it controls the power to the electric heater 17. A similar type circuit arrangement may negate the electric temperature control system and power the electric heater directly from the circuit board and trigger.

Referring now to Figure 3, a range of steel and or tin plate or similar metal, application heads are shown as examples of how hot air may be applied to weed control, shield valuable plants and how mechanical attachments can be incorporated to the hot air process to aid weed control. In these examples the application heads 23, 24, 25, 26, 27 and 28 have a push-on fit to the nozzle. Items 23-28 show a style of heads other designs and connotations may also be included.

Future fixings may include screw fits, locating pins, and a collar locking mechanism. The applfcation heads may be a shrouded head 23, with side and front covers to restrict the flow of hot air and protect neighbouring vegetation, a spoon reflector 24, a wide slot head 25, a tapered head 26, to concentrate heat and mechanical heads such as a head incorporating a trident 27 and a rake 28. The operation of the mechanical heads would be to agitate, dislodge and expose weeds to improve the lethal weeding capability of the hot air process. A further designed application head may include an angled outlet to direct the hot air at a given angle (not shown) or an "extension" head to aid reaching into less accessible places (not shown).

Claims (11)

1. A method of controlling plant vegetation in which a flow of air is generated by a motor-powered device, the air in the flow is heated directly or indirectly and the heated air is directed at plant vegetation to be killed.

2. A method according to claim 1, in which the air is heated to a temperature greater than 80 C.

3. A method according to claim 1 or 2, in which the air is heated to a temperature in the range of from about 80 C. to about 800 C.

4. A method according to claim 1, in which a hand-held tool is used, the hand-held tool including a motor, means for generating a flow of air through the tool, an electric heating element for heating the flow of air through the tool, and an air outlet from which the heated air is directed at the plant vegetation to be killed.

5. A method of controlling plant vegetation, the method being substantially as herein described with references to and as illustrated by the accompanying drawings.

6. An apparatus for controlling plant vegetation, the apparatus including a motor-powered device for generating a flow of air through the apparatus, a heater for heating the flow of air through the apparatus, and an air outlet from which heated air leaves the apparatus to be directed at plant vegetation to be killed.

7. An apparatus according to claim 6, in which the apparatus is an elongate hand-held tool and includes a handle at one end and an air outlet at the other end.

8. An apparatus according to claim 7, in which the heater is provided in the region of said other end.

9. An apparatus according to any one claims 6 to 8, in which the heater comprises an electric heating element.

10. An apparatus according to any one of claims 6 to 9, in which the motor-powered device comprises an electric motor and a fan driven by the electric motor.

11. An apparatus for controlling plant vegetation, the apparatus being substantially as herein described with reference to and as illustrated by the accompanying drawings.