THERMAL WEEDER

Abstract

A gas powered thermal weeder having a burner head for burning gas to generate heat. The burner head has a foot portion for placing in proximity to weeds to be treated with heat generated at the burner head. The burner head is connected by a support tube to a handle portion, with the handle portion and support tube being for use together in supporting and positioning the burner head during the treatment of weeds. The handle portion comprises a gas canister mounting portion to which a gas canister is mountable for supplying gas to the burner head.

Claims

1. A gas powered thermal weeder comprising a burner head for burning gas to generate heat, the burner head having a foot portion for placing in proximity to weeds to be treated with heat generated at the burner head and the burner head being connected by a support tube to a handle portion, the handle portion and support tube being for use together in supporting and positioning the burner head during the treatment of weeds, wherein the handle portion comprises a gas canister mounting portion to which a gas canister is mountable for supplying gas to the burner head.

2. A gas powered thermal weeder according to claim 1 in which the handle portion comprises a gas regulator for regulating gas as it leaves a gas canister mounted on the gas canister mounting portion.

3. A gas powered thermal weeder according to claim 2 in which the gas regulator comprises the gas canister mounting portion.

4. A gas powered thermal weeder according to claim 1 in which the support tube comprises an internal channel for feeding gas from the handle portion to the burner head.

5. A gas powered thermal weeder according to claim 1 in which the handle portion comprises a support connector for connecting an outlet from the gas canister mounting portion to the support tube, the support connector serving to mechanically and fluidically connect the gas canister mounting portion to the support tube, so that in operation gas flows through the support connector and there is mechanical support via the support connector between a carried gas canister and the support tube.

6. A gas powered thermal weeder according to claim 5 in which the support connector comprises a flow carrying portion through which gas flows in operation, and the support connector further comprises at least one support projection which projects from the flow carrying portion and is held in a body of the handle portion.

7. A gas powered thermal weeder according to claim 6 in which the at least one support portion comprises an arm portion that projects away from the flow carrying portion in a direction away from the gas canister mounting portion.

8. A gas powered thermal weeder according to claim 1 in which the thermal weeder comprises an ignition system comprising a piezo-electrically driven actuator provided in the handle portion and connected via an ignition cable to a spark unit at the burner head.

9. A gas powered thermal weeder according to claim 8 in which the support tube comprises an ignition cable channel for housing the ignition cable between the handle portion and the burner head.

10. A gas powered thermal weeder according to claim 1 in which the thermal weeder comprises an air intake for drawing air in to mix with gas as the gas flows into the burner head during operation, wherein the air intake comprises at least one aperture provided in a side wall of a gas mixing passage and a surrounding shroud to shield the aperture, the shroud being cup shaped with a base provided around the gas mixing passage and a rim which is spaced from the side wall of the gas mixing passage and the air intake further comprising an apertured cap portion which fits on the cup shaped shroud and covers the space between the rim and the side wall of the gas mixing passage.

11. A gas powered thermal weeder according to 1 in which the burner head defines a combustion zone where gas is burned in operation to generate heat.

12. A gas powered thermal weeder according to claim 11 in which the thermal weeder is an infrared thermal weeder which is arranged to output infrared radiation for treating an area and wherein a radiant element is provided in the combustion zone.

13. A gas powered thermal weeder according to claim 12 in which the burner head has an inlet for allowing an air fuel mix into a gas mixing chamber and at least one baffle member is provided in the gas mixing chamber at a location between the inlet into the burner head and the radiant element.

14. A gas powered thermal weeder according to claim 11 in which the foot portion comprises a screen bounding one side of the combustion zone and a skirt portion provided around, but spaced from, a periphery of the screen for defining an area to be treated, wherein a wind deflector portion is provided on an underside of the foot portion within an area bounded by the skirt on one edge and bounded by the screen on the other edge.

15. A gas powered thermal weeder according to claim 1 in which the foot portion is provided with at least one wheel for facilitating movement of the foot portion over ground to be treated.

16. A gas powered thermal weeder according to claim 14 in which the foot portion is provided with said at least one wheel towards one end and provided with at least one skid portion towards a second end which is opposite to the first end.

17. A gas powered thermal weeder according to claim 1 in which the handle portion comprises two user grip portions, a first grip poryion of the grip portions arranged to be held by a first hand and a second first grip portion of the grip portions arranged to be held by a second hand in use, wherein the first grip portion is provided at a first location and the second grip portion is provided at a second location which is spaced from the first location, and spaced from the support tube in a direction which is away from the gas canister mounting portion.

18. A gas powered infrared thermal weeder comprising a burner head for burning gas to generate heat, the burner head having a foot portion for placing in proximity to weeds to be treated with heat generated at the burner head and the burner head being connected by a support tube to a handle portion, the handle portion and support tube being for use together in supporting and positioning the burner head during the treatment of weeds, wherein, the burner head defines a combustion zone where gas is burned in operation to generate heat, a radiant element is provided in the combustion zone for emiting infrared radiation when heated, and each side of the combustion zone is bounded by a respective wall portion to avoid foreign objects entering the combustion zone.

19. A gas powered infrared thermal weeder according to claim 18 in which the radiant element comprises a ceramic block.

20. A gas powered thermal weeder comprising a burner head for burning gas to generate heat, the burner head having a foot portion for placing in proximity to weeds to be treated with heat generated at the burner head and the burner head being connected by a support tube to a handle portion, the handle portion and support tube being for use together in supporting and positioning the burner head during the treatment of weeds, wherein, the handle portion comprises a gas canister mounting portion to which a gas canister is mountable for supplying gas to the burner head, the handle portion comprises a support connector for connecting an outlet from the gas canister mounting portion to the support tube, the support connector serving to mechanically and fluidically connect the gas canister mounting portion to the support tube, and the support connector comprises a flow carrying portion through which gas flows in operation, and the support connector further comprises at least one support projection which projects from the flow carrying portion and is held in a body of the handle portion.

Description

[0063] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

[0064] FIG. 1 schematically shows a gas powered thermal weeder carrying a gas canister;

[0065] FIG. 2 is schematic sectional view of the gas powered thermal weeder and gas canister of FIG. 1;

[0066] FIG. 3 is a schematic sectional view showing a handle portion of the gas powered thermal weeder of FIGS. 1 and 2 as well as part of a support tube and a carried gas canister;

[0067] FIG. 4 is a schematic sectional view of a burner head of the gas powered thermal weeder shown in FIGS. 1 to 3;

[0068] FIG. 5 is a schematic view of the burner head of FIG. 5 with the support tube and an air intake arrangement disassembled from the burner head; and

[0069] FIG. 6 is an exploded schematic view of the burner head shown in FIGS. 4 and 5.

[0070] FIG. 1 schematically shows a handheld gas powered infrared thermal weeder 1 with a gas canister 2 mounted thereon. The thermal weeder comprises a handle portion 3 to which the gas canister 2 is mounted and a burner head 4 which is connected to the handle portion 3 via a support tube 5. The support tube 5 serves to mechanically and fluidically connect the handle portion 3, and ultimately the carried gas canister 2 to the burner head 4. The support tube 5 typically will be of metal and may be a metal extrusion say of aluminium.

[0071] In general operation gas is fed from the gas canister 2 via the support tube 5 to the burner head 4 where the gas is burnt for generating heat for treating an area to be treated by the burner head 4. In use the burner head 4 is moved and positioned by a user holding the handle portion 3 so that together the handle portion 3 and support tube 5 serve to support and position the burner head 4 in operation. in use gas flows in passages within the handle portion 3 and within the support tube 5 rather than via an external gas hose.

[0072] FIG. 2 shows a schematic sectional view of the thermal weeder 1. Here can be seen an internal channel 51 of the support tube 5 which is used for carrying gas from the handle portion 3 and ultimately from a carried gas canister 2 to the burner head 4.

[0073] The thermal weeder 1 includes an ignition system 6 having a piezo-electric actuator 61 situated in the handle portion 3 which is connected via a cable 62 to a spark unit 63 provided at the burner head 4. The cable 62 runs in second internal channel 52 which in this embodiment is provided side by side with the gas channel 51 in the support tube 5 The ignition system also includes a grounding cable connected between the actuator 61 and a convenient metallic part in the handle portion 3.

[0074] This arrangement means that first there no external gas hose connection between the gas canister 2 and the burner head 4 in the present embodiment and further the ignition cable 62 is largely housed within the support tube 5.

[0075] FIG. 3 shows parts of the handle portion 3 in more detail.

[0076] The handle portion 3 comprises a body portion 31 which provides a first user grip portion 32 and a second user grip portion 33 (see FIGS. 1 and 3). The body portion 31 also houses other components. The first user grip portion 32 is provided beyond the end of the support tube 5 and can act as one handle for holding the thermal weeder 1 in use. The second user grip portion 33 is spaced away from the first user grip portion 32 and spaced away from the support tube 5. The second user grip portion 33 is useful for holding the device and the first user grip portion 32 is useful for supporting and stabilising the burner head 4 and the thermal weeder 1 overall during operation. The thermal weeder 1 is arranged so that overall with the thermal weeder in an intended operating orientation such as shown in FIG. 2, the centre of gravity of the device overall including a fitted gas canister 2 is located at a location which is “under” the second user grip portion 33. That is to say a vertical drawn through the centre of gravity will intersect with the second user grip portion 33. This means that the user may hold the second user grip portion 33 at what might be termed a balance position for operation of the weeder.

[0077] The piezo-electric actuator 61 and an initial part of the length of the cable 62 are housed within the body portion 31 of the handle portion 3.

[0078] The body portion 31 further houses and supports a gas regulator 21 to which the gas canister 2 is mounted in use. The gas regulator 21 correspondingly comprises a gas canister mounting portion 21a. The gas regulator 21 further comprises an outlet portion 21b and a control knob 21c for controlling the rate at which gas is allowed to flow through the regulator from the gas canister 2 and out of the outlet portion 21b.

[0079] The body portion 31 of the handle portion 3 further houses a support connector 7. The support connector 7 has a flow carrying portion 71 which in this embodiment is in the form an elbow portion. The flow carrying portion 71 is connected to the outlet portion 21b of the regular 21 on the one hand and to an end of the support tube 5 (in particular to an end of the internal gas carrying channel 51 of the support tube 5) on the other hand. Thus, the support connector 7 serves to fluidically and mechanically connect the regulator 21 to the support tube 5. In this embodiment the flow carrying portion 71 is directly connected to the outlet portion 21b of the regulator 21 and directly connected to the support tube 5. This is preferred (as it is simple, compact and effective) but in other cases intermediate parts might be provided and similar advantages obtained, provided there is supporting mechanical connection between the regulator 21 and the support tube 5. It will be noted that the connection between the regulator 21 and the support tube 5 is within the body of the handle portion 31 and also that the gas canister mounting portion 21a is within the body of handle portion 31.

[0080] The support connector 7 serves to mechanically connect the regulator 21 to the support tube 5. In use this means that when the gas canister 2 is mounted to the mounting portion 21a of the regulator 21 there is mechanical connection between the gas canister 2 and the support tube 5 via the regulator 21 and the support connector 7. This arrangement provides support for the gas canister 2 when carried and also avoids the inclusion of any gas hose connection.

[0081] However, this may tend to increase stress on the connections between the gas regulator 21 and support tube 5. That is to say in particular, between the outlet of the regulator 21b and the flow carrying portion 71 on the one hand and between the flow carrying portion 71 and the end of the support tube 5 on the other hand.

[0082] To help minimise these stresses and share the load, the support connector 71 5 also comprises a support portion 72 which projects away from the flow carrying portion 71. In this embodiment, this support portion 72 is an arm which projects in a direction away from the gas regulator 21. This arm portion 72 is captured and held in the body portion 31 of the handle portion 3 to help reduce the stress on the above mentioned connections. The body of the handle portion 31 also io comprises a tube holding sleeve portion 34 into which the support tube 5 is inserted and via which it is supported. The support connector 7 in this embodiment has a generally T-shape with a leg of the T connected to the support tube 5. The grounding cable may for example, be connected to the support portion 72.

[0083] Note that in at least some cases the weeder maybe arranged to allow the connection of a lager gas canister (more commonly termed a gas bottle in those instances) to the weeder via an adaptor (not shown) and a length of hose. Thus the weeder 1 can be used with a gas canister 2 mounted on the gas canister mounting portion 21a for optimum convenience and manoeuvrability as shown in the drawings or can be used with a larger gas canister or bottle connected via a hose and an adaptor to the gas canister mounting portion to give longer operation times. This option can be provided in cases where the handle portion 31 houses a regulator 21 as in the present embodiment and in cases where there is no on-board regulator 21 such that the gas canister mounting portion 21a is provided on another component. In general terms an adaptor (not shown) may be provided for allowing connection of a gas canister or bottle to the gas canister mounting portion 21a via a length of hose.

[0084] FIGS. 4, 5 and 6 show the burner head 4 in more detail. The burner head 4 comprises a body portion 41 which defines a gas mixing chamber 42 in which the gas is mixed with air in use and a foot portion 43 which is arranged to be positioned on the ground in use when treating an area. Together the foot portion 43 and body portion define a combustion zone Z in which the gas or, more accurately, the air-fuel mix is burnt in use. The foot portion 43 has a surrounding skirt 431 which serves to define an area for treatment. That is to say the skirt 431 will tend to contain the heat within the area which it bounds.

[0085] A skid portion 432 is provided at the front of the foot portion 43 with the skid portion 432 depending from the skirt 431 and a wheel is provided 433 at the rear of the foot portion 43. The wheel 433 and skid 432 can help a user in manoeuvring the device during treatment. In practical operation, in some 10 instances, a user will choose to pick the thermal weeder 1 up away from the surface to be treated, move it to the desired location, and then place it down in contact with the surface for treatment. In other instances it may be convenient to push the weeder 1 along between treatment areas with the weeder 1 running on the wheel 433 and optionally the skid 432.

[0086] Housed within the combustion zone Z at a lower portion of the gas mixing chamber 42 is a radiant element in the form of an apertured ceramic block 44. The burner head 4 comprises an air tube 45 which leads into the body portion 41 and provides an inlet into the gas mixing chamber 42. A baffle 46 is provided in the gas mixing chamber 42 and located between the inlet formed by the air tube 45 and the ceramic block 44.

[0087] As seen by considering FIGS. 4 and 5, the end of the support tube 5 nearest the burner head 4 is provided with an injector unit 53. The injector unit 53 comprises an injector element 53a and a coupling tube 53b. The injector unit 53, in particular the coupling tube 53b serves to join the support tube 5 to the air tube 45 of the burner head 4. The injector element 53a serves to inject gas into the interior of the air tube 45 which acts as a gas mixing passage. Apertures 45a are provided in the side walls of the air tube 45 to act as an air intake. Thus, as gas is supplied from the gas canister it travels through the tube 5 and exits the injector element 53b. Here, air is drawn through the apertures 45a into the air tube 45 where the air and gas can mix before entering into the gas mixing chamber 42.

[0088] The baffle 46 serves to control the flow of the air fuel mix through the gas mixing chamber 42 to help ensure mixing and deliver this mix evenly to the ceramic block 44 where it is burnt. The ceramic block 44 is provided with a 5 large number of apertures therethrough such that the gas can be burnt in and around the ceramic block 44 in operation so heating up the ceramic block 44 and causing it to act as a radiant member to allow thermal treatment via emission of infrared radiation. The air-fuel mix tends to burn at the, exposed, lower surface of the ceramic block 44.

[0089] A shroud 8 is provided around the air inlet provided by the apertures 45a. This shroud 8 comprises a conical portion 81 which is provided around the air tube 45 in the region of the apertures 45a and a cap portion 82 which includes apertures 82a. The conical portion 81 serves to shield the apertures 45a in the air tube 4 against eg the effects of wind. The apertured cap 82 allows to air to enter into the conical portion 81 such that it can be drawn in through the apertures 45a in the air tube 45. At the same time the cap 82 covers the space between a rim 81a of the conical portion 81 and the outside wall of the air tube 45 to minimise the risk of foreign objects such as leaves and earth entering the zo conical portion 81 and potentially fouling the air inlets 45a.

[0090] The foot portion 43 includes an expanded mesh screen 434 which is provided within the bounds of the skirt portion 431 and provides a lower boundary to the combustion zone Z. This mesh screen 434 serves to allow heat and exhaust gas to escape the combustion chamber 42 whilst avoiding flames at the ceramic block 44 in use being exposed to the surroundings. The screen 434 can also serve to prevent foreign objects from entering into the combustion zone Z and potentially damaging or fouling the ceramic block 44.

[0091] The screen 434 is supported at a distance away from the ceramic block 44 by (in this embodiment) an extended spacer profile 435, which acts as a wind deflector portion. The spacer profile 435 is provided around the periphery of the screen 434 and extends across (one might say covers) the spacing between the screen 434 and the ceramic block 44. The spacer profile 435 depends from a top wall 436 of the foot portion 43 from which the skirt portion 431 also depends. The spacer profile 435 thus also extends across the spacing between an underside of the top wall 436 and the screen 434. The spacer profile 435 in this embodiment provides a part of the boundary of the combustion zone Z.

[0092] The spacer profile 435 serves to deflect wind that may enter the area bounded by the skirt 431 and allows at least part of the flame on the surface of the ceramic block 44 to be hidden and so not be blown out so easily. If a small portion of the flame remains alight this can then reignite the fuel air mix over the remainder of the ceramic block 44 when the wind/draft subsides.

[0093] As best seen in FIG. 4 the spark unit 63 of the ignition system includes an electrode 63a which is located behind a shielding portion 63b to protect it from external damage. The electrode 63a is located in the region of metallic parts in the foot portion 43, say the shielding portion 63b, such that a spark can be generated between the electrode 63a and those surrounding metallic parts on operation of the actuator 61. Thus in use to light the thermal weeder, a user turns the regulator knob 21c to an on position and operates the actuator 61 to cause a spark to light the air fuel mix in the combustion zone Z.