FIELD OF INVENTION

The present invention relates to a method and device for driving down an earth wire into the ground using an earthing bar with the earth wire attached to the front end ofthe bar

DESCRIPTION OF THE BACKGROUND ART

In the earthing of power line pylons and similarly large objects, it is usual that one attaches the earth wire to the end of a so-called earthing bar, which is driven down into the ground to a depth of 1 to I i metres. For reasons of cost, etc, it is desired that the bar be as thin and light as possible. At present mainly thin-walled tubes are used. A problem is that such a thin-walled, tube-shaped bar can easily bend when being driven down into the ground. Up until now, this problem has not been solved satisfactorily

DESCRIPTION OF THE INVENTION

The object ofthe present invention is to offer a method and a device which can solve the above-mentioned problem. The purpose ofthe invention is also to offer a device that is simple to produce, easy to use in the field and that is not too expensive to make The scope ofthe invention should also include a device which can be used for driving down a homogeneous earthing bar. These and other objectives can be achieved in that the invention is characterized by what is stated in the appending claims. Further characteristics and aspects ofthe invention will be evident from the following description of a preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment ofthe invention will now be described with reference to the accompanying drawings, in which

Fig. 1 is a perspective view of a device according to the invention seen obliquely from above; Fig. 2 shows the same device in axial section,

Fig. 3 shows in axial section a device improved specifically for tube-shaped earthing bars;

The third improvement is that the upper cylinder is supplied with a yoke 20 and the base plate 5 is supplied with a hook 21 that fits onto the yoke 20. When the aggregate has been completely compacted, one can by turning the top tube 10 relative to the base plate 5 bring the yoke 20 in under the top part 22 ofthe hook 21 and in this way assemble the aggregate to its compacted state. The yoke 20 can at the same time function as a carrying handle.

The device 3' functions principally in the same way as the device described above. When a tube-shaped earthing bar is loaded into the device, it is brought up through the bottom opening 1 1 and further through the openings 19, 18 in the guiding plates 17, 16 and threaded onto the guiding pin 15. When the bar is driven down into the ground and the device 3' is brought together, the guiding pin 15, the guiding plates 16, 17 and the bottom tube 7 work together as very effective stiffening for the tube, and as extremely efficient prevention against tube breakage.

In the embodiment shown in Fig 5 the telescopic aggregate is turned "upside down" compared with the two earlier embodiments. The widest telescopic tube T is according to this embodiment joined with the base plate 5, while the narrowest tube 10' is supplied with an upper end closure 12, which in turn is supplied with the top part 6, arranged for the application of a power machine tool such as a dipper bucket. The two central telescopic tubes 8' and 9' are in this case supplied with guiding discs 16, 17 with guiding openings 18, 19 in their bottom ends. These holes 18, 19 have the same dimension as the opening 1 1 in the base plate and the inner diameter in the upper tube 10'. Together the holes 11, 18 and 19 and the top tube 10' form breakage protection for the earth bar, whether it be a tube or a homogeneous bar.

A yoke/carrying handle 20 is in this case mounted onto the upper part ofthe bottom tube T and a cooperating hook 21, 22 is arranged onto an extension ofthe end closure 12 to serve as a carrying handle and as a coupling device when the aggregate is folded together.

the notched area 13 in the base plate. If the bar 1 should bend out sideways due to the resistance ofthe ground, it will be supported by the cylinders in the support telescopic aggregate ofthe device 4, which avoids breaking ofthe bar 1, even if it is relatively thin. In other words, the deflection will be minimal due to support from the surrounding telescopic cylinders 7-10. In the maximally extended position, the support device has a total length of 1.25 m. The opening 11 and the lowest cylinder have an inner diameter of 19 m , while the top cylinder has an inner diameter of 49 mm.

The cylinders 7-10 are eventually driven completely together, i.e. so that the top cylinder 10 is brought down in contact with the base plate 5. The device 3 is then removed.

Remaining is a piece ofthe earthing bar 1, which stands up about two decimeters above the surface ofthe ground, equalling the total height ofthe compacted device 3 as desired.

The device shown in Figs 1 and 2 can be used for tube-shaped as well as homogeneous earthing bars. Figs 3 and 4 show a device 3' specifically for tube-shaped earthing bars. Its basic construction is the same as the previous embodiments (and therefore the relating details have been given the same reference numerals as in Figs 1 and 2) but it contains three improvements compared to the previous embodiments. Firstly, there is a guiding pin 15 attached to the top end ofthe telescopic aggregate and it is attached by its upper end to the end closure 12 below the top part 6. According to the embodiment the guiding pin is made ofa pointed rod but can also be constructed ofa tube with a point at the bottom end. The length ofthe guiding pin 15 is somewhat less than the length ofthe device 3' when joined completely. The diameter ofthe guiding pin 15 is somewhat less than the inner diameter ofthe tube-shaped earthing bar which is to be driven down into the ground by means ofthe device.

The second improvement is that both ofthe telescopic tubes 8,9 in the centre ofthe aggregate are supplied with guiding plates 16, 17 at their upper ends. These plates 16, 17 show central holes 18, 19 with diameters only slightly larger than the outer diameter of the tube-shaped earthing bar.

CLAIMS

1. Method for driving down an earth wire into the ground with an earthing bar (1), where the earth wire (2) is attached to the front end ofthe bar, characterized in that the bar is arranged in a supporting unit (4) consisting of several movable telescopic cylinders (7-10) assembled together so that the supporting unit rests in the vertical position with an upper end closure (12) against the upper end ofthe bar and turned downwards with one ofthe end cylinders (7) ofthe supporting unit towards a base plate (5), which is contacted with the ground, where the bar is pointed in the supporting unit so that its front end with the attached earth wire will project below said lowest cylinder (7) ofthe supporting unit and below the base plate (5), and that the supporting unit is pressed together towards the base plate from above so that the earthing bar is driven through an opening (11) in the base plate down into the ground under the influence ofa vertical force exerted on the mentioned end closure ofthe top end ofthe bar, by which the bar draws the earth wire (2) with it below, through or at the side ofthe base plate.

2. Device for driving down an earth wire into the ground with an earthing bar with the earth wire attached to its front end, characterized in that it comprises a supporting unit containing several movable telescopic cylinders (7-10) assembled together, that the top cylinder (10) ofthe supporting unit is completed with an end closure (12) intended to be turned upwards on use ofthe device, that the bottom cylinder (7) ofthe supporting unit is bound to a base plate (5) around an opening (11) or notch in the base plate, and that the opening (11) or equivalent as well as the inner diameters of the cylinders are large enough so that the bar can be inserted through the base plate in the aggregate to contact with the mentioned end closure.

3. Device according to claim 2, characterized in that the base plate has at least one notch (13) for the earth wire.

4. Device according to claim 2, characterized in that the base plate is cut off on one side by the supporting unit for the earth wire.

Fig 6 shows a device 3 a in which the telescopic aggregate consists of three tubes 7a, 8a and 9a for supporting the earthing bar 1 as it is driven down into the ground. It is evident that this is only an example, and that the number of tubes can also be two, four or more. Compared with the previously shown embodiments, the device 3 a shows a couple of improvements or supplements. The first is a central tube or spear 30 which is fastened to the end closure 12 and to the outer tube 9a. The spear 30 is completed with a point 31 of which the upper cylindrical part reaches into and is connected with the tube 30. The cylindrical part ofthe point 31 has a diameter matching the inner diameter ofthe tube-shaped earthing bar 1, so that the latter can be threaded onto the point 31 for contact with the bottom edge ofthe tube 30. The tube 30 has a length which in principle matches the length ofthe collapsed device 3 a, as shown in Fig 6. The purpose ofthe tube 30 is to be able to drive down an earthing bar completely or almost completely into the ground.

Further contained within the telescopic tubes 8a and 9a, i.e. in all tubes except the inner telescopic tube 7a, are machined grooves 32 and 33 respectively between the upper and lower parts 36, 37 and 38, 39 respectively. A protrusion 34 on the inner tube 7a extends out into the groove 32 in the tube 8a, and in a similar way a protrusion 35 on the tube 8a extends out into the groove 33 in the outer tube 9a. The purpose with the protrusions 34 and 35, cooperating with the grooves 32 and 33 respectively and with the end parts 36, 37 and 38, 39 respectively, is to function as a unifying body for the device 3a as the telescopic aggregate is drawn out to its full length. In the case ofthe telescopic device containing further telescopic tubes, also these are supplied with lengthwise grooves, end parts and protrusions in the same way as shown in the figure. The device 3a is also (in the same way as the device in Figs 3 and 4) supplied with a yoke/carrying handle 20 on the outer tube and a cooperating hook 21, 22 on the base plate 5. The top part 6 is embodied with an application arrangement by which a dipper bucket or similar machine tool can push down the earthing bar into the ground during collapsing ofthe telescopic device 3 a, and by which the spear 30 drives the bar down right to the ground surface during the final phase.