GB2122511A

GB2122511A - Weed killing apparatus and method

Info

Publication number: GB2122511A
Application number: GB08316479A
Authority: GB
Inventors: Marko Makar
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-06-30
Filing date: 1983-06-16
Publication date: 1984-01-18
Also published as: CA1196318A; GB2122511B; GB8316479D0

Abstract

A weed killing apparatus comprises a heat shield (48) having an open first end and a second end spaced apart therefrom. A spray nozzle (44), has an outlet communicating with the interior of the heat shield. A liquid heater means (32) has an outlet communicating with the inlet of the spray nozzle and serves to heat a liquid passing through it. A liquid supply means communicates with the heater means, and supplies a flow of liquid through the heater means to the spray nozzle. Preferably the liquid supply means supplies a flow of water which is raised to about boiling by the heater means. A method of killing weeds is also disclosed and which can be performed by the preceding apparatus, and which comprises briefly spraying the weeds with hot gas or vapour, preferably with hot water near its boiling temperature. <IMAGE>

Description

- SPECIFICATION Weed killing apparatus and method This invention relates to a method, and an apparatus particularly suited for carrying out the method, for killing'weeds, Traditionally, weeds in agricultural opera tions or in domestic plots have been physi cally removed, typically by hand. Manual re moval is usually accomplished with the assis tance of a few simple garden implements. In larger-scale operations, it is common to re move weeds simply by tilling the earth in the area from which weeds are to be removed.

However, to carry out such an operation with any greater efficiency than the manual method it is necessary to have equipment which will till a very large area of soil at a particular instance. However, because the weeds are often found among desired plants, it is often impracticable to use such equip ment and resort must be had again to mahual removal.

Another method of weed removal, particu larly over large areas of nonagricultural land, is by the application of herbicides. Such a method is undesirable in that desired plants, for example in an agricultural operation; may also be affected to some extent by the heribi cide, and also undesirable from health and environmental considerations. It has recently become extremely desirable in view of enlight ened health and environmental considerations, to provide a nonchemical method which will efficiently destroy undesired plants, such as weeds.

Various types of apparatus have been de scribed in the past which have attempted to avoid the problem of affecting desirable plants, which apparatus usually consists of a means for spraying a herbicide within an open ended frustoconical or cylindrical shield, the open end of the shield being placed over-the plant or weed to be destroyed. Such devices are disclosed in U.S. Patents Nos. 2,841,923 and 4,199,896. Although such devices tend in the short run to reduce immediate effects on desired plants, they still-suffer from the fact that a herbicide is required which typi cally has undesirable health or environmental impact over the long run, and which over the long run can leach through the soil affecting desirable plants in the same general area.

It is therefore desirable to have a method of killing weeds which will have the advantages described above, and an apparatus for readily carrying out such a method.

A weed killing apparatus in accordance with the invention comprises a heat shield having an open first end and a second end spaced apart from the first end; a spray nozzle having an inlet and an outlet communicating with the interior of the shield; a liquid heater means having an inlet, and an outlet communicating with the inlet of the spray nozzle, for heating a liquid passing therethrough; and liquid supply- means communicating with the heater means, for supplying a flow of liquid through the heater means to the spray nozzle.

Preferably, the spray nozzle and liquid heater means are disposed adjacent the heat shield. Usefully, the liquid heater means heats the liquid passing through it to about 1 00 C.

The liquid supply means is preferably for supplying a flow of water.

Of the various possible shapes of the heat shield, it is preferred that it be either cylindrical, frustoconical, or has an opening in its first end in the shape of an elongated slit.

A method of killing weeds is also provided which comprises briefly spraying them with a hot gas, liquid vapour, or a hot liquid. Where a liquid vapour is used, it is advantageously at about 100 C.

Preferably, a liquid is used near its boiling temperature.

Usefully, the equivalent of up to several ounces of liquid are sprayed on each weed.

Preferably, the liquid is water and up to several ounces are sprayed on each weed.

Such spraying of liquid water is advantageously done over a period of up to several seconds.

Usefully, about one to two ounces of water are sprayed on each weed over a period of about one second. The weeds may be advantageously sprayed on the base of their stems.

Embodiments of the invention will now be described with reference to the drawings, in which: Figure 1 is a partially broken, perspective view of an apparatus embodying the present invention; and Figure 2 is a cross section along the line 2-2 of Fig. 1.

The weed killing apparatus shown in the drawings has a handle portion 2 with a bottom section 4, and a top section 9 contoured to receive the hand of a user. A threaded female receptacle 5 receives a threaded male end of a length of flexible- hose 7. Hose 7 has a female receptacle 8 adapted to receive the male end of a typical garden hose. A wire mesh filter (not shown) is conveniently provided within the receptacle 5. The receptacle 5 communicates through a tube 1 6 with a valve mechanism 18, the valve mechanism 1 8 being spring loaded so as to be normally closed, and to be opened when a handle 14 is lifted upwardly.A recessed, standard three prong male plug 10 is provided in the upper section 9 of the handle 2, and is electrically connected to an electric switch 12, which may be of the push button type which is sequentially thrown between its open and closed positions by pressing. An elongated tube 20 extends downward from the lower section 4 of the handle 2 to a cylindrical shaped cover 26, which has an open lower end, and a generally cylindrical housing 32 of a water heater designated generally as 31. A conduit 22 is disposed within the tube 20 and has an upper end communicating with the outlet of the valve 1 8. An electrical cable 24 also extends within the tube 20 and is electrically connected at its upper end to one side of the switch 12.

The cover 26 is connected to the lower end of the tube 20 and is provided with a number of vent holes 28 at an upper end of it, and an insulating layer 30 on its inside surface. The cover 26 is maintained in spaced relation with the water heater 32 by a plurality of circularly disposed studs 33 connected between the heater 32 and cover 26. The housing 32 of the water heater 31 is also connected at its upper end to the lower end of tube 20. A lower end 23 of conduit 22 terminates within the lower part of the housing 32, while a conduit 34 has an open upper end 36 terminating within the upper part of the housing 32, and a lower end 38 extending below the housing, through a threaded portion 52 attached to the housing 32, and communicating with a spray nozzle 44.An electric heating coil 40 is disposed about the lower end 23 of conduit 22 and about second conduit 34, in the manner shown, and has its end terminating outside the housing 32 in a three prong plug arrangement 42 which is electrically connected to cable 24 through a thermostat 43.

A pressure relief valve 46 is provided in the wall of the housing 32 and communicates with the interior of it.

The liquid spray nozzle 44 is in effect only a series of openings in an upper end 50 of a frustoconical shaped transparent heat shield 48, which upper end 50 has a threaded receptacle which is removably screwed on the threaded portion 52. The spray shield 48 is provided with an open lower end 51.

To operate the weed killing apparatus as described above, a user threads the female end 8 of the hose 7 to the male end of a garden hose. The female end of a typical three prong extension cord is received in plug 10. The upper portion 9 of the handle 2 is gripped and trigger 14 is pulled upward so as to cause water to flow through conduits 16 and 22 into chamber 32, filling that chamber, and then out the second conduit 34 to the spray nozzle 44 and into the heat shield 48.

When a spray of liquid is observed within the transparent heat shield 48, the trigger 14 can then be released so that liquid flow through the water heater 31 and spray nozzle 44 will cease. Switch 1 2 can then be depressed to close it and activate the heating coil 40.

Thermostat 43 is set at close to 100"C so that when the water is heated to near boiling temperature, heating coil 40 will be deactivated by the thermostat 43. The wattage of heating coil 40 is selected so that the water within the chamber 32 will be heated to boiling temperature within one or two seconds. Following that time, the user simply places the heat shield 48 over the base of the stem of the weed to be killed and again squeezes trigger 14 for a period of about one second.This will again cause a spray of now almost boiling water, to be emitted through the spray nozzle 44 and into the heat shield 48. it has been found that most weeds of a size typically encountered in a lawn, garden or agricultural operation (about a few inches in width and height), can be killed when spray nozzle 44 is dimensioned to spray about one or two ounces of water over a period of about one second. The area of the weed sprayed begins to wilt immediately. It has also been found that some stubborn weeds, for example dandelion, may tend to commence growing again. However, it has also been found that the new shoot need only be treated once in the manner as described, and the weed will not usually then again regrow.

During operation of the apparatus, the cover 26 and its insulating layer 30, prevent damage to desirable plants by creating a heat barrier between the water heater 31 and desirable plants. The cover 26 is cooled by air circulating into the lower end of the heat shield 26, and upwards through the holes 28 therein. The temperature of the water heating means 31 is prevented from becoming too high by the thermostat 43. The heat shield 48 confines hot water sprayed in it so as to minimize heat loss and prevent damage to desirable adjacent plants. The heat shield 48 also prevents spray nozzle 44 from contacting the ground and possibly becoming plugged with soil.

The apparatus described can be alternately provided with heat shields of different shape.

Other particularly useful heat shield shapes include generally cylindrical shapes for taller weeds, and a shape with an elongated slit in a first end, the latter shape being particularly convenient for eliminating weeds between rows of crops. The heat shield and appropriately dimensioned spray nozzles are changed on the apparatus simply by threading or unthreading them on the portion 52.

The method which is performed by the above apparatus, that is the method of killing weeds by briefly spraying a small amount of almost boiling water, can of course be performed by apparatus other than that described above. In addition, it is possible to vary the temperature of the water sprayed through the spray nozzle. However, if the temperature is much higher than the boiling point, a stronger walled housing 32 would have to be constructed to retain the resulting pressure therein. Of course, lowering the temperature of the water sprayed on the weed results in reduced effectiveness. Either such variation in temperature can be accomplished in the above apparatus simply by resetting the ther mostat 43.It is also possible to modify the method of killing weeds by spraying them with liquids other than water or with a hot liquid vapour, (that is, the hot vapour of a substance normally liquid at temperatures encountered outdoors), such as steam. It is preferred to use water of course for obvious reasons. In addition, it is preferred to use hot water rather than steam since for the latter an apparatus of more complex construction is required to deliver the larger volume of steam with the same heat content. Although the amount of water and time over which it is sprayed on a weed can be varied, it has been found that most weeds of the size earlier described, will be destroyed with about one or two ounces of water heated to near boiling temperature, and sprayed on each weed over a period of about one second.It has also been found that a greater amount of near boiling water sprayed over the entire foliage of a larger weed than described, will produce similar results. However, a larger heat shield may be required.

Thus, it will be seen that the above apparatus and method provides a means of easily killing most weeds which does not require the use of herbicides or other chemicals which may over the short or long run have real or perceived undesirable health or ecological consequences.

The apparatus described above can be typically made primarily of plastic, with the exception of the housing 32 and heating coil 40 of the water heater 31. However, obviously the apparatus could be constructed primarily of light weight metal or other suitable material as desired.

As will be apparent to those skilled in the art in light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention, within the scope of the appended claims.

Claims

1. A weed killing apparatus comprising a heat shield having an open first end and a second end spaced apart from the first end; a spray nozzle having an inlet, and an outlet communicating with the interior of said heat shield; a liquid heater means having an inlet, and an outlet communicating with the inlet of said spray nozzle, for heating a liquid passing therethrough; and liquid supply means communicating with said heater means, for supplying a flow of liquid through said heater means to said spray nozzle.

2. A weed killing apparatus according to Claim 1, wherein said spray nozzle and liquid heater means are disposed adjacent said heat shield.

3. A weed killing apparatus according to Claim 1 or 2, wherein said liquid heater means is adapted to heat liquid passing therethrough to about 100 C.

4. A weed killing apparatus according to Claim 1, 2 or 3, wherein said liquid supply means is adapted for supplying a flow of water through said liquid heater means to said spray nozzle.

5. A weed killing apparatus according to Claim 1, 2, 3 or 4, wherein said heat shield is cylindrical in shape.

6. A weed killing apparatus according to Claim 1, 2, 3 or 4, wherein said heat shield is frustoconical in shape.

7. A weed killing apparatus according to Claim 1, 2, 3 or 4, wherein the first end of said heat shield has an opening in the shape of an elongated slit.

8. A method of killing weeds comprising briefly spraying them with a hot gas.

9. A method according to Claim 8, wherein the gas is a liquid vapour at about 100"C.

10. A method of killing weeds comprising briefly spraying them with a hot liquid.

11. A method according to Claim 10, wherein the liquid is near its boiling temperature.

12. A method according to Claim 9, 10 or 11, wherein the equivalent of up to several ounces of liquid are sprayed on each weed.

13. A method according to Claim 9, 10 or 11, wherein the liquid is water and up to several ounces are sprayed on each weed.

14. A method according to Claim 11, wherein the liquid is water and up to several ounces are sprayed on each weed over a period of up to several seconds.

15. A method according to Claim 14, wherein one to two ounces of water are sprayed on each weed over a period of about one second.

16. A method according to Claim 11, 14 or 15, wherein the weeds are sprayed on the base of their stems.

1 7. A method according to Claim 11, 14 or 15, wherein the weeds are sprayed on their foliage.

1 8. Every novel feature and every novel combination of features disclosed herein.