NZ593651A - An insulated drop-down electric fence for passage of large irrigators - Google Patents

Abstract

Disclosed is an electric fence which includes electric fencing material supported between a series of spaced posts. The fencing material includes a drop-down section and a sprung section. The drop-down section includes means for electrically insulating the drop-down section and means for securing the drop-down section to a ground anchor so as to inhibit lateral movement of the drop-down section.

Description

Received at IPONZ on 5 March 2012 COMPLETE SPECIFICATION New Zealand Patent Application No. 593651 Filed: 22 June 2011 TITLE: ELECTRIC FENCE AND COMPONENTS FOR ELECTRIC FENCE Technical Field The present invention relates to an electric fence which facilitates the use of travelling irrigators. The present invention further relates to components for such a fence.

Background Art Where an area of land is irrigated, it has become common practice to use large-scale irrigators, for example a centre pivot irrigation in which a long irrigation boom, mounted at intervals on wheels, rotates about a central point to irrigate each part of the area sequentially. Large linear irrigators, consisting of a long irrigation boom mounted at intervals on wheels and arranged to travel in a straight line, are also known.

However, it frequently is necessary to subdivide the irrigated area with fences; typically, fencing is needed for efficient stock management and/or to maximise effective grazing of the paddocks being irrigated. To irrigate the entire area, the irrigator needs to be able to pass over or through the fences. Obviously, one possibility is to set gates in the fence lines, spaced apart at the same spacing as the irrigator wheels. However, this is an expensive option, and also is labour intensive, because the gates have to be opened in front of the irrigator and closed behind the irrigator.

In view of the above problems, it has become the practice to provide fences with springs at intervals, so that the fence is able to stretch sufficiently to allow the fence wires to be depressed to at or near ground level to allow an irrigator to pass over the fence without damage. Once the irrigator has passed over the fence, the springs simply pull the fence upright again.

Disclosure of Invention An object of the present invention is the provision of an improved electric fence design, and components for achieving this design, for areas which are intended to be irrigated. 1 Received at IPONZ on 5 March 2012 The present invention provides an electric fence which includes electric fencing material supported between a series of spaced posts, wherein said fencing material includes a drop-down section and a sprung section; said drop-down section including means for electrically insulating said drop-down section and means for securing said 5 drop-down section to a ground anchor so as to inhibit lateral movement of said dropdown section.

As used herein, the term 'electric fencing material' includes wire, braid and tape. The preferred embodiments of the invention is described in the terms of a wire fence, 10 because wire is the most commonly used fencing material for this type of electric fence. However, the invention is equally applicable to other electric fencing materials.

Preferably, said means for electrically insulating said drop-down section includes a length of insulating tubing arranged to cover any portion of said electric fencing 15 material in the drop-down section which contacts the ground in use, so as to insulate said portion of said electric fencing material from the ground.

Preferably also, said means for securing said drop-down section to a ground anchor includes a stay of insulating material one end of which is secured to said insulating 20 tubing and the other end of which is secured to the ground anchor.

In a preferred embodiment of the invention, the electric fencing material consists of two or more substantially parallel lengths of wire, braid or tape each of which incorporates a sprung section, and said means for electrically insulating said drop-25 down section includes a length of insulating tubing arranged to cover each portion of said wire, braid or tape in the drop-down section which contacts the ground in use, so as to insulate said portion from the ground; and wherein said means for securing said drop-down section to a ground anchor includes a stay of insulating material one end of which is secured to the insulating tubing which covers the uppermost length of wire, 30 braid or tape when said fence is in the normal in use position; the or each other lengths of insulating tubing being fitted with an insulating sleeve extending through the diameter of the tubing with the longitudinal axis of each sleeve substantially perpendicular to the longitudinal axis of the tubing; said stay being arranged to pass through the or each said insulating sleeve. 2 Received at IPONZ on 5 March 2012 The present invention further provides a sprung section for an electric fence, said sprung section including a coil spring formed with a connector at each end, each connector being designed to provide connection means spaced from the adjacent end of said coil spring. Preferably, each connector also is adapted to be a removable snap-fit onto an insulator and/or a strainer, and to provide an anchorage for a stay-wire.

Brief Description of the Drawings By way of example only, a preferred embodiment of the present invention is described in detail, with reference to the accompanying drawings in which:- Figure 1 is a diagrammatic side view of a fence in accordance with the present invention; Figure 2 is a side view, on a larger scale, of a spring in accordance with the present invention; Figure 2a is a side view, similar to Figure 2, showing an alternate spring design; Figure 3 is a side view, on a larger scale, of a drop-down section in accordance with the present invention; and Figure 4 is a side view, on a larger scale, of a typical strainer and insulator fitted to the spring.

Best Mode for Carrying out the Invention Referring to the drawings, an electric fence 10 in accordance with the present invention includes a series of spaced fence posts with electric wires strained between the posts, in known manner; Figure 1 of the drawings shows three of these posts, 11,11a,12, supporting two spaced parallel electric wires 13, 14. It will be appreciated that any number of wires may be supported between the posts, depending upon the intended use of the fence.

Each of the wires 13, 14 is provided with a spring 16, 17 and a drop-down section 10a. It will be appreciated that Figure 1 is not drawn to scale, and in practice the distance between the adjacent posts 11,11a,12 will be substantially longer than depicted. The length and strength of each of the springs 16, 17 is selected so as to allow sufficient extension of the corresponding wire 13, 14 that the corresponding wire can be 3 Received at IPONZ on 5 March 2012 depressed to ground level (indicated by line 20) when the drop-down section 10a is depressed by an irrigator wheel, as hereinafter described. However, the strength of each of the springs 16, 17 is such that the corresponding wire is tensioned adequately for the fence to function in the normal manner.

The springs 16, 17 are identical. The spring 16 is described in detail with reference in particular to Figure 2, and comprises a tightly wound portion 21 with a connector 22, 23 formed at each end of the spring, integrally with the coiled portion of the spring.

The connector 22 includes a straight portion 24, one end of which becomes the coiled portion 21 of the spring and the other end of which is bent through approximately 90° to form an engagement portion 25, and then formed into a hook 26 at its free end.

The connector 23 also includes a straight portion 27, one end of which becomes the 15 coiled portion 21 of the spring and the other end of which is bent through approximately 90° to form an engagement portion 28, then formed into a hook 29 at its free end.

The engagement portion 25 on the connector 22 is designed to engage with a fence 20 strainer 30. The strainer 30 depicted in Figure 4 is a known type of ratchet strainer which includes a pair of spaced ratchet wheels 31 formed integrally with a common axle 32 and mounted upon a supporting bracket 33, which provides two opposed arms 34 formed integrally with each other and with a U-shaped joining portion 35. The length of the engagement portion 25 is such that it is slightly longer than the width of 25 the supporting bracket 33, so that the strainer 30 can be connected to the connector 22 by sliding the connector 22 into the U-shaped joining portion 35 of the bracket and snapping the connector 22 into the position shown in Figure 4.

The engagement portion 28 of the connector 23 is designed to engage as a snap fit 30 with one of the apertures in an "egg" insulator 36, with the engagement portion 28 bearing against the side of the aperture.

The snap fit connections between the connectors 22, 23 and the strainer and insulator respectively mean that the components can be connected rapidly and accurately, and 35 broken or damaged components can be replaced easily. 4 Received at IPONZ on 5 March 2012 It will be appreciated that different types of strainer and insulator may be substituted, in which case the shape and configuration of the engagement portions 25, 28 are varied as necessary. Also, the springs 16, 17 may carry an insulator at each end, rather than at one end only, and the engagement portions are varied as required.

When the connectors 22, 23 are engaged with the strainer 30 and the insulator 36 as described above, the hooks 26, 29 respectively on the connectors extend on the same side of the strainer and insulator respectively as the coiled portion 21 of the spring. A stay-wire 40, made of flexible wire or braid is formed with a crimped loop 41 at each 10 end, is hooked between the hooks 26, 29 and extends down the middle of the coiled portion 21. The purpose of the stay-wire 40 is to prevent over-extension (and thus permanent deformation) of the springs 16, 17 and the length of the stay-wire is equal to the required extension of the corresponding fence wire 13, 14 when depressed by the irrigator wheel, without the stay-wire being unduly tensioned. For clarity, the stay-15 wire 40 is shown only in Figures 2 and 4.

It will be appreciated that the length and strength of each of the springs 16, 17 and the length of the corresponding stay wires 40 will depend partly on the intended purpose of the fence (example the type of stock it is intended to contain) and the material from 20 which the majority of the length of the fence is formed. For a typical two wire fence made of high tensile wire and intended to contain cattle, each spring will exert approximately 40 KG load on the corresponding wire, to tension the fence adequately, and the stay wire is selected such that it will be pulled tight with a load of approximately 140 KG; this gives adequate protection to the fence wire, which would 25 normally start to stretch at a load of about 170 KG. Thus, the stay wire 40 will protect the spring from over extension and permanent stretching, up to the breaking load of the stay wire (about 300 kg).

In use, the insulator 36 is connected to the adjacent fencepost 12 by a length of wire, 30 in known manner, and the strainer 30 is connected to the electric wire 13, also in known manner.

The strainer 30 is used in known manner to tension the fence wire 13 to the required degree of tension.

Received at IPONZ on 5 March 2012 For some fence configurations, neither a strainer nor an insulator is required, in which case the connectors at each end of the spring are formed as shown in Figure 2a, with a straight portion 52 at each end of the spring 21, and the free end of the straight portion 52 coiled to form an eye 53 to which both a fence wire and a stay-wire can be connected. In addition, a spring can be formed with an eye on one end and a connector for a strainer or an insulator on the other end, as required for any particular configuration offence.

It should be noted that the presence of the straight portions 24, 27, 52 is important -they allow space for the easy connection of the stay wire 40, together with space to accommodate the excess length of the stay wire 40 without tangling or kinking the wire; in the case of portions 24 and 27 they also provide a sufficient space to allow easy connection of the spring to a strainer or an insulator.

Referring to Figures 1 and 3, the drop-down section 10a is the section offence which is designed to be depressed to ground level as an irrigator wheel passes over it. The position of the drop-down section is selected such that the drop-down section is located at the part, or at each part, of the fence where an irrigator wheel will contact the fence as the irrigator moves. Obviously, the number of drop-down sections on each fence depends on the type of irrigator used and its pattern of movement.

The drop-down section 10a includes a pair of parallel insulating tubes 18, 19 located on the fence wires 13, 14 respectively, with the fence wire passing down the centre of the tube. Each of the tubes 18, 19 is made of a tough, impact resistant insulating material such as low-density polyethylene which will protect the corresponding wire from being damaged by the irrigator wheel and will prevent the corresponding electric wire 13, 14 from shorting out when it contacts the ground. The length of each of the tubes 18, 19 is such that when the wires 13, 14 are depressed by the irrigator, the whole of the portion of the wires 13, 14 in contact with the ground is covered by the tubes 18, 19, thus preventing the wires 13, 14, from shorting out when they contact the ground. Typically, the tubes 18, 19 are about 1.5 m long.

For the drop-down section 10a of the fence to be depressed by the irrigator wheel, it is necessary to drop-down section is anchored to the ground so that the drop-down section cannot move in the direction of movement of the irrigator by any significant distance:- if this happens, the fence 10 will simply be moved with the irrigator in the 6 Received at IPONZ on 5 March 2012 direction of motion of the irrigator until either the irrigator stalls or the fence is pulled apart. However, if the drop-down section 10a is anchored, it is prevented from moving forward by any substantial amount and thus tends to pivot downwards, allowing the irrigator wheel to pass over the top.

To anchor each drop-down section, each of the tubes 18, 19 is fitted with a tethering stay 45, 46; the stays are positioned adjacent each end of the tubes.

Each stay 45, 46 is made of a tough, flexible insulating braid. One end of each stay 45, 46 is secured to the upper tube 18, (i.e. the tube which is uppermost when the fence is in its normal position); the stay then passes through the lower tube 19 as described below, and the lower end of each stay is secured to a ground anchor 47, 48 (Figure 1) by any suitable means, e.g. a shackle 49 as shown in Figure 3.

The pressure exerted on the tubes 18, 19 by the irrigator wheels can be substantial, and this can cause the stays to cut into the tubes. To prevent this, each tube 18, 19 is fitted with a sleeve 50, 51 which extends diametrally through each corresponding tube, with the longitudinal axis of the sleeve substantially perpendicular to the longitudinal axis of the tube. The length of each sleeve 50, 51 is greater than the diameter of the tube 18, 19 such that the ends of each sleeve project beyond the tube.

In the case of the lower tube 19, the stay simply passes through the sleeve 51; since the sleeve projects slightly beyond the sides of the tube 19, the stay 45 cannot cut into the surface of the tube. Also, the sleeve 51 insulates the stay from the electrified wire passing through the tube 19. This is important, because although the stay is of insulating material, it is likely to be wet and thus would conduct electricity if in contact with the electrified wire.

In the case of the upper tube 18, the upper end of the stay 45 is tied around the exterior of the tube 18 in a figure of eight knot on each side of the sleeve 50, secured by a cable tie; this distributes the load exerted by the stay 45 on the tube 18, and the sleeve 50 prevents the stay from sliding in either direction along the length of the tube 18.

The sleeves 50, 51 are made from an insulating material, preferably an abrasion resistant insulating material such as nylon 12. 7 Received at IPONZ on 5 March 2012 In use, when the irrigator wheel contacts the fence, the tubes 18, 19 protect the wires 13, 14 from damage, and the corresponding springs 16, 17 allow the wires 13, 14 to be depressed towards the ground so that the irrigator wheel can pass over without 5 becoming entangled or damaging the fence. 8 Received at IPONZ on 5 March 2012

Claims (5)

Claims

1. An electric fence which includes electric fencing material supported between a series of spaced posts, wherein said fencing material includes a drop-down section and a sprung section; said drop-down section including means for electrically insulating said drop-down section and means for securing said drop-down section to a ground anchor so as to inhibit lateral movement of said drop-down section.

2. The fence as claimed in claim 1 wherein said electric fencing material is selected from the group consisting of: wire, braid, tape.

3. The fence as claimed in claim 1 or claim 2, wherein said means for electrically insulating said drop-down section includes a length of insulating tubing arranged to cover any portion of said electric fencing material in the drop down section which contacts the ground in use, so as to insulate said portion of said electric fencing material from the ground.

4. The fence as claimed in claim 3, wherein said means for securing said dropdown section to a ground anchor includes a stay of insulating material one end of which is secured to said insulating tubing and the other end of which is secured to the ground anchor.

5. The fence as claimed in claim 1, wherein the electric fencing material consists of two or more substantially parallel lengths of wire, braid or tape, each of which incorporates a sprung section, and said means for electrically insulating said drop-down section includes a length of insulating tubing arranged to cover each portion of said wire, braid or tape in the drop-down section which contacts the ground in use, so as to insulate said portion from the ground; and wherein said means for securing said drop-down section to a ground anchor includes a stay of insulating material one end of which is secured to the insulating tubing which covers the length of wire, braid or tape which is uppermost when said fence is in the normal in use position; the or each other lengths of insulating tubing being fitted with an insulating sleeve extending across the diameter of the tubing with the longitudinal axis of each sleeve substantially perpendicular Received at IPONZ on 5 March 2012 to the longitudinal axis of the tubing; said stay being arranged to pass through the or each said insulating sleeve. The fence as claimed in any one of the preceding claims, wherein said sprung section includes a coil spring formed with a connector at each end, each connector being designed to provide connection means spaced from the adjacent end of said coil spring, and to provide anchorages for a stay wire which is secured at one end to one connection means, extends the length of the coil spring and is secured to the other connection means at the other end of said coil spring, so as to limit the extension of said coil spring. The fence as claimed in claim 6, wherein one or both of said connectors on each coil spring is adapted to be a removable snap fit onto an electric insulator or onto a wire strainer. An electric fence substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.