WO2002019817A1

WO2002019817A1 - Thermal weed control device

Info

Publication number: WO2002019817A1
Application number: PCT/FR2001/002689
Authority: WO
Inventors: Thierry Templai
Original assignee: Thierry Templai
Priority date: 2000-09-05
Filing date: 2001-08-29
Publication date: 2002-03-14
Also published as: FR2813500A1; AU2001287789A1; FR2813500B1

Abstract

The invention concerns a thermal weed control device (1) adapted to be towed by a vehicle (30). It comprises a first chassis (2) mounted on wheels (12) and towed by said vehicle and at least a second chassis (6), mounted on roller (9) and track shoe (8) and coupled to said first chassis with at least one degree of freedom in translation relative thereto, transversely to the towing direction of said vehicle. The first chassis carries a fuel oil tank (4) and an electric generator (3). The second chassis carries a fuel oil burner (13) and a combustion chamber (22) corresponding to an opening (21) oriented towards the ground. The fuel oil burner (13) is supplied with fuel by the tank (4). It can be ignited and maintained in operation through the electric generator (3).

Description

Thermal weed control device

The present invention relates to a thermal weeding device.

Conventionally, a thermal weeding device consists of a gas burner connected to a pressurized gas tank and is mounted on a chassis intended to be coupled or towed by a vehicle, for example an agricultural tractor.

The operation of a known thermal weed control device is as follows. The burner is lit and the thermal weed control device is driven at a constant speed above the surface of land to be weeded. The heat produced by the burner, often associated with a nozzle, causes the plant cells of harmful plants to burst. The flow of flaming gas channeled through the nozzle makes it possible to concentrate the heat produced in an area located at the feet of crop plants, such as a vine, without affecting the parts of these plants which could be destroyed by heat. Thus, it is possible to carry out a precise weeding, eliminating the harmful plants under alignments of cultivating plants, for example a vine. Such a device poses a number of problems. First of all, it is very heavy, in particular because of the large mass of the gas tank which is at least equal to that of the mass of the gas. Then, the Lower Calorific Power (PCI) of the gas is low compared to that of other fuels. For example, the PCI of city gas is 3500 Kcal / Kg, while that of a liquid fuel is 10 200 Kcal / Kg. Furthermore, the risk of explosion should not be overlooked. Indeed, although safety devices are used to cut off the gas supply to the burners in the absence of flames, they have too long a reaction time and a pocket of highly explosive gas forms in the nozzle.

The present invention aims in particular to minimize or eliminate these drawbacks.

To this end, it provides a thermal weeding device suitable for being towed by a vehicle, characterized in that it comprises a first chassis mounted on wheels and towed by said vehicle and at least a second chassis, mounted on wheels and / or on skids and coupled to said first chassis with at least one degree of freedom in translation relative to the latter, transverse to the direction of towing of said vehicle, said first chassis carrying at least one fuel tank and said second chassis carrying at least one burner with oil and a corresponding combustion chamber with an opening directed towards the ground.

The oil burner conventionally has a safety device which interrupts the injection of oil if the flame is smothered, which has the advantage in this invention of not polluting the ground. User intervention is also required to restart it.

The use of fuel oil makes it possible to reduce the mass of the fuel tank in a ratio close to 1 to 6 compared to a thermal weeding device operating with gas under pressure. The risks of explosion are also considerably reduced since its flash point temperature is 55 ° C, while it is 40 ° C for kerosene and 21 ° C for petrol.

It is in particular the implementation to support a burner and the corresponding combustion chamber of a second chassis with a certain freedom of transverse movement relative to a first chassis which, for its part, supports heavy elements such as the tank, which makes it particularly advantageous to use an oil burner instead of a pressurized gas burner. For example, in a case where the second chassis has a degree of freedom in lateral translation relative to the first chassis, which can be obtained for example by using a coupling by connecting rods oscillating in a horizontal plane, obstacles, such as seedlings of crop near which weeding takes place, being on the path traveled by the second chassis, can be bypassed with precision, following an automatic control or not, without having to modify the direction of towing followed by the towing vehicle and the first chassis. Therefore, the combustion chamber can be very close to the areas to be weeded. Thus, the flame produced by the burner and developing in the combustion chamber will allow thermal weeding of an area of the soil located close to the opening of this combustion chamber. This allows the use of an oil burner rather than a pressurized gas burner.

According to another aspect of the present invention, the second chassis is coupled to the first chassis with a degree of freedom in translation relative to the latter in a lateral direction relative to the towing direction of the vehicle, and the second chassis comprises means guide adapted to bear on an obstacle to urge said second chassis in a lateral direction relative to the towing direction of the vehicle.

A degree of freedom in lateral translation of the second chassis relative to the first chassis can be obtained for example by using a coupling by connecting rods oscillating in a horizontal plane. Such a guide means, for example a curved slide laterally installed along one side of the second chassis, will come into contact with the first with an obstacle on the road to the second chassis. The obstacle by sliding against the surface of the guide means will cause the lateral shift of the second chassis which will thus automatically bypass the obstacle. The second frame can therefore advance in an alignment of cultivated plants and bypass each foot while remaining close, since the guide means remains in contact with the foot.

Advantageously, the device also comprises a return means adapted to bias the second chassis laterally in alignment by relative to the first chassis corresponding to a rest position between two obstacles.

Thus, once the obstacle has been crossed, the second chassis will return to a rest position, corresponding for example to a path in an alignment of obstacles such as the feet of crop plants.

According to another aspect of the present invention, the second chassis is coupled to the first chassis with a degree of freedom in translation relative to the latter in a vertical direction relative to the towing direction of the vehicle. A degree of freedom in vertical translation of the second chassis relative to the first chassis can be obtained for example by using a coupling by connecting rods oscillating in a vertical plane. When the main chassis is on a drop, the chassis which is not yet on this drop is neither likely to be lifted in the air, nor to support the entire weight of the device, taking into account the freedom in vertical translation.

Advantageously, the second chassis comprises a guide means adapted to bear on an obstacle to urge said second chassis upwards.

The guide means, for example an upwardly curved pad installed under the second chassis, will come into contact with the first with an obstacle on the road to the second chassis, for example a terrain accident.

The obstacle passing under the guide means will cause the upward movement of the second chassis which will thus avoid the obstacle.

All this aspect of the invention makes it possible to implement a second relatively low chassis relative to its support points, wheels or shoes, so that the combustion chamber can be very close to the ground, without the risk that the latter s clings to an obstacle.

According to another aspect of the present invention, the first chassis comprises a jack and transmission means adapted to lift the second chassis.

In this way, the second chassis can be lifted so as not to land on the journeys which precede or follow a weeding operation. According to another aspect of the present invention, protective means are provided between the combustion chamber and the other elements of the device.

The characteristics of the invention mentioned above, as well as others, will appear more clearly on reading the following description of an exemplary embodiment, said description being made in relation to the accompanying drawings, among which: FIG. . 1 is a schematic elevation view of a thermal weeding device according to the invention, and FIG. 2 is a schematic plan view of part of the thermal weeding device of FIG. 1.

A thermal weeding device 1 according to an exemplary embodiment of the present invention is adapted to be towed by a tractor vehicle 30, as can be seen in FIG. 1. A coupling device 36 of the well known type offers a certain degree of freedom in pivoting in a horizontal plane and in translation in a vertical direction of the towed device 1 relative to the tractor 30.

Overall, with reference to FIG. 1, the thermal weeding device 1 comprises a main chassis 2 mounted on wheels 12 and secondary chassis 6, each mounted on a rear roller 9 and front pads 8, and coupled to the main chassis 2 by means of articulations 11. Fig. 2 represents one of the two secondary chassis 6 acting behind one of the wheels 12 of the main chassis 2. The other secondary chassis, not shown, is coupled symmetrically behind the other wheel 12 of this main chassis 2.

The main chassis 2 consists of a frame 20A comprising two longitudinal members connected by crosspieces, two front uprights 20B, connected to horizontal beams 20C extending obliquely to form a triangle at the top of which is formed a bore allowing connection to the coupling device 36, and two rear uprights 20D at the end of which the wheels 12 are connected.

The wheels 12 are large wheels suitable for uneven terrain. They are each mounted at the end of an arm 19 pivotally mounted on the lower end of the corresponding rear upright 20D. Cylinders electric 5 intervene between each upright 20D and the arm 19 of the corresponding wheel 12. The ends of these jacks 5 are pivotally mounted respectively on the upright 20D and the arm 19. In this way, these jacks 5 control the inclination of the arm 19 relative to the upright 20D and thus make it possible to adjust the elevation relative to the ground of the chassis 2. The electrical actuation control of these jacks is done by means of a command 18 installed on the tractor 30 and connected to the jacks by a cable. A safety switch 17 for flame arrest during lifting is installed on the arm 19.

At the front of the frame 20A of the chassis 2 is fixed an oil tank 4. This tank is provided at the rear of its upper end with a fuel outlet orifice, through which a suction tube 23 passes. fuel connected to pipes 25, and an inlet orifice 24 for returning surplus fuel through which pipes 26 pass.

Under the frame 20A of the chassis 2, below the fuel oil tank 4, hangs an electric generator 3 driven, by means of a cardan joint 32, by a shaft driven by the engine of the tractor 30, as it is well known. The generator 3 is provided with two electrical sockets 15. On one of these sockets is connected a power supply cable for the jacks 5.

The chassis 2 is further provided with backfire protection plates 33, 34 and 35. As can be seen in FIG. 1, the plate 33 is installed between the side members of the rear part of the frame 20A up to the uprights 20D. The plate 34 is installed between the uprights 20D, its upper end being welded to the front end of the plate 33. Finally, the plate 35 is suspended from the uprights 20D and goes almost to the ground, its upper end being articulated so the plate pivots when an obstacle touches it and disappears in front of this obstacle.

At the lower end of each of the rear uprights 20D intervenes the articulation 11 connecting the main chassis 2 to a corresponding secondary chassis 6. This articulation 11 comprises a shaft 11A and a shaft 11C between which two connecting rods 11B are articulated. As can be seen in FIG. 1, the shaft 11A extends transversely against the end of the upright 20D. It is mounted to rotate freely on the 20D upright. Similarly, the shaft 11C extends transversely against the front of the secondary chassis 6, parallel to the shaft 11 A. It is also mounted free to rotate on the secondary chassis 6. From made of the freedom in rotation of the shafts 11A and 11C, a vertical movement of the chassis 6 relative to the chassis 2 is authorized, equivalent to a vertical translation. The rods 11B, of the same size and parallel, connect the ends of the shafts 11A and 11C on which they are articulated, so that the whole of the articulation 11 forms a deformable parallelogram. By deforming, the parallelogram formed by the articulation 11 allows lateral movement of the chassis 6 relative to the chassis 2 equivalent to lateral translation. A spring 10 is stretched between the shaft 11 A and the innermost link 11B relative to the device 1. A stop 40 acting on the end of the shaft 11A on which this link 11B is articulated prevents tilting towards the exterior of the device 1 of this link. This spring 10 cooperating with this stop 40 fixes, as the rest position of the articulation 11, the alignment position shown in FIG. 2 in which the links 11B extend along the longitudinal axis of the device 1, that is to say the direction of towing. When the chassis 6 is moved laterally towards the interior of the device 1 and that, consequently, the articulation 11 is deformed, the spring 10 biases the articulation 11, and therefore the chassis 6, towards the rest position represented on the Fig. 2.

The two secondary chassis 6, of much smaller dimensions than those of the main chassis, are coupled side by side behind respectively one and the other wheels 12 of the main chassis. Each of these chassis 6 is made up, as can be seen in FIG. 2, two longitudinal members 29 between which are installed a combustion chamber 22, a roller 9 and a shoe 8. The roller 9 intervenes between the two rear ends of the longitudinal members on which it is mounted free to rotate. The diameter of the roller 9 is much smaller than that of the wheels 12 of the main chassis.

The combustion chamber 22 is rectangular in shape and occupies most of the space between the two longitudinal members 29. It acts just after the roller 9. Its height is small, comparable to the diameter of the roller 9. It is arranged roughly in look of the roller 9, with a slight offset in its lower part, so that it does not come into contact with the ground. However, it is very close to the ground. The opening 21 of this combustion chamber extends all along its lower part, on the side of the chassis 6 facing the outside of the device 1. Above this combustion chamber 22 is installed an oil burner 13 connected to the tank 4 by the fuel supply pipes 25 and return of the surplus fuel 26. The electrical supply for lighting and keeping the burner in operation are provided by the electric generator 3 to which the burner is connected by a cable 27 connected to one of the sockets 15 of this generator. An electric control of the burner is provided by the control 18 fixed on the tractor and connected to the burner 13 by the cable 28.

As seen in Fig. 1, at the front of the chassis 6, is installed the pad 8 forming the front support of the chassis 6 adapted to slide on the ground. The front of this pad 8 is curved upwards. The rear part of this shoe, extending horizontally, arrives just below the combustion chamber 22.

The shaft 11C of the joint 11 acts transversely on the front of the combustion chamber 22 just above the shoe 8, as seen in FIG. 1. As seen in FIG. 2, this shaft 11C extends only over a portion of the front of the chassis 6 located towards the interior of the device 1. In the rest position of the joint 11 in which the links 11B extend in the direction towing, the center of the shaft 11C is substantially aligned relative to the arm 19 supporting the wheel 12 located on the corresponding side and, therefore, an entire part of the frame 6 is offset laterally outwardly to this wheel 12.

As seen in Fig. 2, the spar 29 which is located on the side of the frame 21 facing outwards from the device 1, that is to say the spar which is located above the opening 21 of the combustion chamber 22, is provided with a forward extension 7 curved towards the inside of the device 1. In this way, this spar 29 forms a slide adapted to bear on an obstacle appearing in the path of the chassis 6. When an obstacle slides against the curved part 7 of the spar 29, it will exert on the frame 6 a transverse force urging this frame towards the interior of the device 1. The end 7 of the spar 29 is bent so as to pass through the entire area situated in front of the frame 6 which is laterally offset towards the outside with respect to the wheel 12 of the main chassis when the articulation 11 is in its rest position shown in FIG. 2. As seen in Figs. 1 and 2, the combustion chamber 22 and the roller 9 are capped by a protective grid 14 making it possible to avoid any contact with the metal parts heated by the flame developing in the combustion chamber 22. As can be seen on the Fig. 1, the chassis 6 are further suspended from the rear part of the frame 20A of the chassis 2 by chains 16. The length of these chains is such that, in a weeding position shown in FIG. 1, they are not stretched. On the other hand, when the chassis 2 is raised under the action of the jack 5, these chains are tensioned and cause the chassis 6 to be lifted such that the rollers 9 and the pads 8 of these chassis are no longer in contact with the ground.

In operation, the device 1 is towed between rows of plants at a constant speed suitable for weeding. The oil burners 13 of the two chassis 6 are ignited and then kept in operation by the generator 3, under the control of the control 18. Flames are then generated in the combustion chambers 22 of the chassis 6. The heat produced by the burners 13 associated with combustion chambers 22 causes the plant cells of harmful plants to burst. The tractor 30 and the main chassis 2 pass between two rows of plant feet 50 (see FIG. 2), while the portions of the chassis 6 which are offset laterally outward relative to the wheels 12 of the chassis 2 move in the alignments of feet 50 respectively on either side of the device 1. The subsequent operation of the device 1 will only be described through the example of the chassis 6 shown in FIG. 2, the other chassis 6 having a symmetrical operation.

The curved end 7 of the spar 29 will come into contact with the first one with a foot 50 located on the road of the part of the chassis 6 offset laterally outward relative to the wheel 12. The obstacle sliding against the surface outside of the longitudinal member 29 forming a slide will generate a lateral force acting on the chassis 6. This force causes the offset towards the interior of the chassis 6, which makes it possible to deform the articulation 11. The action of the spring 10 causes the foot 50 to remain in contact with the beam 29. The chassis 6 will thus bypass the foot 50 by tightening it closely. The flame produced by the burner 13 will come out somewhat from the opening 21 of the chamber combustion 22, thus coming to weed under the foot 50. After the foot 50 has passed the rear end of the longitudinal member 29 forming a slide, the spring 10 will bring the joint 11, and consequently will bring the frame 6, in the the rest alignment shown in FIG. 2 where the curved end of the beam 29 faces a new foot 50.

When an obstacle such as a ground accident is on the road of the chassis 6, the shoe 8 will come into contact with this obstacle first. The obstacle passing under the guide means will cause the upward movement of the second chassis, thanks to the rotation of the shafts 11A and 11C, which will thus avoid the obstacle. Once the obstacle has passed, the chassis 6 of course descends under the effect of its weight. Similarly, when the chassis 2 is on a drop, the chassis 6 which is not yet on this drop is neither lifted in the air, nor pushed against the ground by supporting the entire weight of the device, due to the freedom in vertical translation authorized by the rotation of the shafts 11 A and 11C.

When the weeding has been carried out between two rows of plants, the tractor unit 30-towed device 1 makes a turn to position itself between two other rows of plants. Similarly, the tractor unit 30-device 1 towed must make trips to go to the cultivated field to weed or to leave this field.

During these journeys made between two weeding operations, the jack 5 supplied by the generator 3 will advantageously be actuated under the control of the control 18 in order to lift the chassis 2 by tilting the arm 19 and, consequently, to lift the chassis 6 pulled by the chains 16 so that these frames leave the ground.

In the event of a possible backfire, the protective plates 33, 34 and 35 will confine these flames to a rear interior zone of the device 1, preventing these flames from reaching elements of the device 1, such as in particular the oil tank 4, but also the electric generator 3, the wheels 12, and of course, the tractor vehicle 30.

Claims

1) Device (1) for thermal weeding adapted to be towed by a vehicle (30), characterized in that it comprises a first chassis (2) mounted on wheels (12) and towed by said vehicle and at least one second chassis (6), mounted on a roller (9) and / or on pads (8) and coupled to said first chassis with at least one degree of freedom in translation relative to the latter, transverse to the direction of towing of said vehicle, said first chassis carrying at least one oil tank (4) and said second chassis carrying at least one oil burner (13) and a corresponding combustion chamber (22) with an opening (21) directed towards the ground. 2) thermal weed control device according to claim 1, characterized in that said second chassis (6) is coupled to said first chassis (2) with a degree of freedom in translation relative to the latter in a lateral direction relative to the direction for towing said vehicle (30), and said second chassis (6) comprises a guide means (29, 7) adapted to bear on an obstacle (50) to urge said second chassis (6) in a direction lateral to the direction of towing of said vehicle.

3) thermal weeding device according to claim 2, characterized in that said device (1) comprises a return means (10) adapted to bias laterally said second chassis (6) in alignment with said first chassis (2) corresponding in a rest position between two obstacles (50).

4) thermal weed control device according to any one of the preceding claims, characterized in that said second chassis (6) is coupled to said first chassis (2) with a degree of freedom in translation relative to the latter in a vertical direction by relative to the towing direction of the vehicle.

5) A thermal weeding device according to claim 4, characterized in that said second chassis (6) comprises a guide means (8) adapted to bear on an obstacle to urge said second chassis upwards.

6) A thermal weeding device according to any one of the preceding claims, characterized in that said first frame (2) comprises a jack (5) and transmission means (16) adapted to lift said second chassis (6).

7) thermal weed control device according to any one of the preceding claims, characterized in that protective means (14, 33, 34, 35) are provided between said combustion chamber (22) and the other elements (3, 4 , 12, 30) of the device.