AU733410B2 - Electric fence device - Google Patents

Description

1..

S F Ref: 373407D1

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name and Address of Applicant: Fred Nordberg Koppargatan 19 S-426 71 Vastra Frolunda

SWEDEN

grae Nerdborg de\.U N'ISSON Actual Inventor(s): Address for Service: Invention Title: Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Electric Fence Device The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5845 ELECTRIC FENCE DEVICE Electric fences for enclosed pasture-land are previously known and appreciated for being simple and effective. They consist of a grounded mains- or battery-operated pulse generator for high voltage and low power and, connected thereto, a smooth metallic wire which is carried by insulating poles so as to surround the enclosed pasture-land. At first contact with the wire the domestic animals learn that it gives an unpleasant electric shock and thereafter avoid subsequent contact. To date simple stainless metallic wire has been used as wire material, in more sophisticated applications woven into a thin ribbon, which makes it more visible. The previously known type of electric fences have however, a considerable disadvantage. Young domestic animals which have not yet come into contact with the electric fence often approach it with such a speed that they are not restricted by the electric shock before the wire has already been torn off by their rush.

The same situation applies to wild animals striving to pass the fence and not being aware S of its effect. This way openings in the fence will occur and the cattle will scatter before 15 the owner has observed the damage. The animals may then destroy valuable cultivations and cause work and trouble for the owner. The invention is a safe and economic solution to this and other problems.

Accordingly, an aspect of the invention provides an electric fence assembly for *o use with a generator of high voltage electric pulses, said assembly including: 20 a plurality of posts; a considerably elastically-stretchable string having an outer surface being electrically conductive on at least part thereof formed from an elastic member and at least one electrically conductive thread combined with said elastic member, said string being attached to said plurality of posts defining an enclosure; said string also including restricting thread means having a first orientation relative to said elastic member when said string is attached to said posts, and having a second orientation having a substantially longitudinal alignment with said elastic member, said restricting thread means approaching said second orientation as said string is I:\DayLib\UBCC\O 1369.doc -2progressively more stretched and substantially restricting said string from further stretching once said second orientation is reached; and whereby, upon impact with a moving animal, said elastically-stretchable string deflects sufficiently to prevent it from breaking while said restricting thread means restricts said string against excessive stretching.

The invention will now be described by way of an embodiment according to the annexed drawing, wherein Fig. 1 shows a section of the string; Fig. 2 shows the string in a side view; Fig. 3 shows a portion of the enclosure; Fig. 4 shows a portion of the enclosure in a horizontal section.

0o According to Fig. 1 an elastic and electrically conductive string is formed around a synthetic rubber core 1 which preferably is divided into several threads, an envelope of tubular braided plastic threads 2 and a number of metal threads 3 included 15 in the braid. The plastic material is preferably a high quality polyamide, e.g. one being known under the commercial denomination 6006, and is treated against UV-radiation degradation. The metallic thread is comprised of stainless steel with a diameter of *000 o* o0 oer0.15 0.3 mm. The tubular braid allows the string to be stretched out to the length 1 where the plastic threads 2 lie against each other in an almost longitudinal direction and 20 it is dimensioned such with respect to the core 1 that the latter thereby is stretched to 00about two times its length in the state of rest. The outer diameter of the string is about 4 mnm in its state of rest. A string which is formed in such a way is electrically conductive by the metallic threads being braided into its surface and is elastically stretchable because of the association between the rubber core and the braided envelope, but the stretchability is restricted by the lengths of the plastic threads. In order to secure the association between the core and the envelope, the string should be provided with a knot near all free ends. The properties of the string makes it ideal for replacing previously used metallic wires and ribbons in electric fences. It is thereby preferably hung on a post according to Fig. 3 which is comprised of a piece of a thin X- I:\DayLiblIBCC\01369.doc profile 5 of carbon fibre reinforced plastic material and which is provided with a pointed end 6 for pressing down into the ground and a movable attachment means 7 for the string. The attachment means 7 has the same shape as a boat anchor and is positioned obliquely with respect to the profile 5 in order to allow it to be hooked together with a similar attachment means of a neighbouring post of the same type as is illustrated on Fig. 4. The purpose of this is to provide the easiest way of arranging an easily opened place in the fence. The strings which are tied around the respective attachment means contact each other by this hooking together and thereby provide electrically conductive connection. If the post carrying the upper attachment means is slightly pressed down into the ground, it is simple to simultaneously pull it out from the ground and from the mutual connection between the attachment means so as to open the fence. Since both the profile 5 and the attachment means 7 are made from electrically insulating materials, the post may be gripped and lifted simply by the hands.

an When mounting the fence the string is stretched to about 3/4 of its possible length 15 and is successively attached to the previously mounted posts which are placed 15 20 m apart, by winding it one turn around the attachment means 7. By the fence being mounted this way the risk of it being run down by rushing animals is eliminated because its stretchability gives the animals time to slow down under the influence of the electric S. shocks from the string. The animal is not injured and the string will stretch itself straight 20 again when the animal changes direction. The considerably better visibility of the string compared to a simple metal wire also reduces the risk of the animals running on to it.

This may be enhanced by using plastic threads in several different colours in the envelope of the string.

Even if the above described embodiment of an elastic string is the most qualified for the intended use, the scope of this invention also encloses several other embodiments.

In its most simple form it is a rubber string which by mixing or impregnation with electrically conductive material is provided with a sufficient conductivity for the high voltage electrical pulses also on the surface. In another embodiment very thin threads of metal are mixed with equally thin threads of synthetic fibres and spun according to the I:\DAYLIB\LIBCC01369.doc -4method known from the knitwear industry such as to result in a so called tricot string.

Such a string has a considerable elastic stretchability and may be twisted together to the thickness and strength necessary for electric fences. Alternatively such a string may be used for spinning around a rubber core. Moreover, a smooth steel wire which is wound into a helical spring and surrounds a rubber core may form the desired string.

Naturally all mentioned embodiments of elastic strings may be used in combination with other kinds of posts and attachments than the ones mentioned above.

I'D]AYLIB\LIBCCW1369.doc

Claims (6)

1. An electric fence assembly for use with a generator of high voltage electric pulses, said assembly including: a plurality of posts; a considerably elastically-stretchable string having an outer surface being electrically conductive on at least part thereof formed from an elastic member and at least one electrically conductive thread combined with said elastic member, said string being attached to said plurality of posts defining an enclosure; said string also including restricting thread means having a first orientation relative to said elastic member when said string is attached to said posts, and having a second orientation having a substantially longitudinal alignment with said elastic member, *said restricting thread means approaching said second orientation as said string is progressively more stretched and substantially restricting said string from further stretching once said second orientation is reached; and ooo0 15 whereby, upon impact with a moving animal, said elastically-stretchable string deflects sufficiently to prevent it from breaking while said restricting thread means oooo restricts said string against excessive stretching. 0000

2. An assembly as claimed in claim 1, wherein said string comprises at least one electrically conductive thread intertwined with at least one electrically non- conductive plastic thread, said conductive and non-conductive threads being arranged as a tubular braid surrounding a rubber core, wherein the length of said tubular braid in an unstretched state being approximately one half the length of said tubular braid in the considerably stretched state. [R:\LIBCCjOI 765.doc:JJP -6-

3. An assembly as claimed in claim 1, wherein the string is knitted into a tricot string including restricting thread means and said at least one electrically conductive thread.

4. An assembly as claimed in claim 3, wherein the tricot string is spun around a rubber core.

An assembly as claimed in any of the previous claims, wherein the posts are provided with a movable anchor-shaped attachment means for each string- *4 0 0 0000 0000 000000 0 15 *000 0 0 0000 00 0 00 00 0 0000 0 0 0* 0

6. An electric fence assembly, substantially as described herein with reference to the accompanying drawings. DATED this first Day of February, 2001 Fred Nordberg Patent Attorneys for the Applicant SPRUSON FERGUSON [R:\LIBCC]01765.doc:JJP