GB2492565A

GB2492565A - Apparatus and method for laying conduit

Info

Publication number: GB2492565A
Application number: GB201111468A
Authority: GB
Inventors: David Reddy
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-07-05
Filing date: 2011-07-05
Publication date: 2013-01-09
Also published as: GB201111468D0

Abstract

An apparatus for laying conduit has a first mass 1 and a second mass 2 each comprising a ferromagnetic material, and a gripper 3 secured to the second mass and adapted to receive an end of a conduit 20. At least one of the first and second masses comprises a magnet. An end of the conduit is attached to the gripper, and the second mass is passed into a space 17 covered by a surface 18 such as a floor. The first mass is then placed against the surface on the outside of the covered space to draw the second mass against the surface inside the covered space by magnetic attraction. The first mass may then be drawn along the surface so that the second mass is also drawn along the surface by magnetic attraction. The gripper may be directly attached to the second mass but is preferably connected by a tether 4 which is sufficiently long that the second mass exits the covered space before the gripper and the conduit enter it. The apparatus can be used to lay electrical cables or pipes.

Description

APPARATUS AND METHOD FOR LAYING CONDUIT

Technical Field of the Invention

The present invention relates to an apparatus and method for laying conduit such as electrical cabling or piping through a covered space.

Background to the Invention

Laying conduits such as cabling and pipes under floors or through wall or ceiling cavities may be an awkward and time-consuming task. This may entail passing aflexible cable or pipe through a confined and inaccessible space which may be cluttered with detritus. obstructed by joists and existing pipes or cabling. One labour-intensive approach is to take up floorboards in order to lay under-floor pipes or cables.

However, tools have been developed which simplify the process. For example, an extendable push/pull rod with a looped or hooked end attachment may be used. The rod is poked along an under-floor, ceiling or wall cavity either before or after attaching an end of a cable to the end attachment. However, this type of tool may be large and bulky, and may have many detachable parts that are easi'y misplaced. Furthermore, such a tool may be awkward and time consuming to use, requiring a long and unwieldy rod to be pushed past obstructions that would norma'ly cause it to buckle or deviate from an intended path. Another problem with such a product is that it is not scalable, i.e. an increase in the required distance to be spanned by an under-floor cable results in the rod becoming progressively and prohibitively more unwieldy and impractical to use. Even once the push/pull rod has been pushed through a covered space to the approximate vicinity of its intended destination, it may be difficult to locate precisely where the rod's end is to be found without the aid of a large opening into the space for locating and retrieving the rod.

To address this problem, US 2004/0 16428 proposes a cable puller which consists of a ferromagnetic metal plate tied to one end a length of string. A magnet is used to draw the metal plate along a cavity in a drywall or ceiling, and the string is then pulled to draw a cable through the cavity.

US 2008/0048160 proposes a cable puller with an elliptical felTomagnetic metal mole' tied to a length of string. The mole is drawn along inside a drywall cavity or under a carpet by a magnet until it reaches a hole at the desired cable location, whereupon it is retrieved from the hole, a cable is looped through a hole in its end, and then the string is pulled to draw the mole back the way it came, and with it the cable.

Dropping a cable from ceiling height to floor level typically entails a drop of around 2.5 metres. which is aided by gravity. By contrast, laying cable under a floor may entail much greater distances in large rooms and is hindered by gravity as the cable will tend to fall away from beneath the floor and out of reach. The continuous expanse of a wall panel or carpet would offer relatively Uttle snagging resistance to a metal plate as it is drawn along by a magnet. However, uneven floorboards may present an insurmountable obstacle to a metal plate being drawn along beneath them by a magnet.

The uneven undersides of floorboards may also have splinters and protruding nails that snag. trap, or loosen a tied or looped cable or a knotted string.

Neither of the above magnetic cable pullers is therefore suitable for laying cables or pipes underneath a floor. Both systems rely on pulling a cable that is tied or looped to the pulling tool. Manually looping or tying a cable or stung well enough to ensure that the cable pulling tool does not release the cable inside the wall or floor cavity may be awkward and fiddly, especially for a user wearing gloves or whose hands are coated with dust. This is particularly a problem for drawing a cable under a floor, since typically larger distances may be covered and the greater likelihood of the string or cable snagging or resisting means that the knot or loop must withstand considerable tension without working loose as it is tugged along.

Objects of embodiments of the present invention therefore include the provision of an improved tool and method for laying a conduit through a covered space, the tool and method being simple, convenient, reliable, and suitable for laying a conduit under a floor.

Summary of the Invention

According to a first aspect of the present invention, there is provided an apparatus for laying conduit, the apparatus having a first mass comprising a ferromagnetic material, a second mass compnsing a ferromagnetic material, and a gripper secured to the second mass and adapted to releasably grip an end of a conduit, wherein at least one of the first and second masses comprises a magnet.

The gripper may be secured to the second mass by a flexible tether. The tether may comprise string, cord, twine, webbing. tape, wire, cable, or chain. Conveniently, the tether may comprise a cord of synthetic fibres. The tether may have a length of at least one metre and preferably of at least three metres. Conveniently, the tether may have a length of at least five metres.

At least one of the first and second masses may comprise a permanent magnet. At least one of the first and second masses may comprise a neodymium permanent magnet.

One of the masses may comprise steel. At least one of the first and second masses may be substantially disk shaped. At least one of the first and second masses may have chamfered or rounded edges. At least one of the first and second masses may be substantially ellipsoidally shaped, and may be substantially shaped as an oblate spheroid.

At least one of the first and second masses may comprise a housing substantially encasing a ferromagnetic material. Conveniently, the housing may be formed of plastic, such as medium-or high-density polyethylene. At least one of the first and second masses may comprise a smooth surface formed from a low-friction material.

The first mass may have a handle adapted to accommodate one or more digits of a hand, and may have a grip with a textured surface and/or a surface formed from a high-friction material, such as a synthetic rubber material. The second mass may be substantially bullet-shaped or may be shaped as substantially a prolate spheroid.

The gripper may have a smooth, convex outer surface, and may have a streamlined shape. The gripper may be substantially bullet-shaped, may be substantially ellipsoidally shaped, and may be shaped as substantially a prolate spheroid or truncated prolate spheroid. The gripper may comprise a gripping mechanism for releasably gripping an end of a conduit. The gripping mechanism may comprise an aperture for receiving an end of a conduit and a screw operable to grip a conduit against a surface of the aperture, or may comprise a clamp, such as a self-tightening clamp. The gripper may comprise a low-friction material, and may be substantially formed of plastic. The gripper may be adapted to receive an electrical cable, and may be adapted to receive a pipe.

The apparatus may include a spacer for keeping the first and second masses spaced apar when not in use. Conveniently, the apparatus may include a self-retracting reel for retracting and storing the tether when not in use.

According to a second aspect of the present invention, there is provided a method of laying a conduit through a space covered by a surface, the method including the steps of providing an apparatus for laying conduit as described above, attaching an end of a conduit to the gripper, passing the second mass into a space covered by a surface, placing the first mass against the surface on the outside of the covered space to draw the second mass against the surface inside the covered space by magnetic attraction, and drawing the first mass along the surface so that the second mass is also drawn along the surface by magnetic attraction.

Where the gnpper is secured to the second mass by a flexible tether, the method may include the steps of retrieving the second mass from the covered space and pulling on the tether to draw the gripper and conduit through the covered space. The conduit may be an electrical cable, or may be a pipe. The surface may be a floor, a ceiling, or a wall surface. The covered space may be an under-floor space or ceiling space, or may be a drywall cavity.

Detailed Description of the Invention

In order that the invention may be more clearly understood an embodiment thereof will now be described, by way of example only, with reference to the accompanying drawings, of which: Figure I shows an apparatus for laying conduit according to an embodiment of the present invention; Figure 2 shows the apparatus of Figure 1 in use during a first stage of laying a conduit under a floor; and Figure 3 shows the apparatus of Figure 1 in use during a second stage of laying a conduit under a floor.

The conduit laying tool shown in Figure 1 consists of a first magnetic block (1), a second magnetic block (2). a gripper (3) for releasably gripping an end of a conduit, and a tether (4) securing the second magnetic block and the gripper to one another. The first (1) and second (2) magnetic blocks each comprise a disc-shaped neodymium permanent magnet(S) encapsulated in a housing (6) formed from a low-friction pbstic materia' such as medium-or high-density polyethylene. The housing has a smoothly contoured shape that resembles an oblate spheroid or a disc-shape with chamfered or smoothed edges.

The tether (4) may be fed through a small hole (7) in the gripper (3) and/or the housing of the second magnetic block (2) and tied with a knot (8) to prevent it from coming loose. Alternatively, it may be tied to a ring, hook, or other fastening that is screwed into, embedded in, or integral to, the housing of the second magnetic block and/or the gripper, or may be embedded in the substance of the moulded plastic of the second magnetic block housing and/or the gripper during injection moulding of the plastic.

The gripper (3) has an internal channel (lO) which forms an aperture (11) in an end face of the gripper fui-thest from the end to which the tether is attached. The intemal channel has a cylindrical shape chosen to accommodate a particular size of cable or pipe.

A grub screw (12) in the side of the gripper is effective to releasably grip the conduit against the inside of the interna' channel, and can be manuafly tightened to ensure that the conduit is securely held. Two or more radially oriented grub screws may be provided, which maybe offset in an axial or a circumferential direction relative to one another.

The conduit laying tool is shown in use in Figures 2 and 3. The tool is intended for laying a cable under a floor, although many alternative uses are envisaged, such as laying under-floor pipes, dropping cables or pipes inside a wall cavity or laying them above a ceiling, or-more generally-laying a conduit through any inaccessiHe space covered by a surface.

Two access points (15, 16) are required i ito the floor cavity (17) or other covered space through which the conduit will be laid. Each access point must bean opening into the covered space that is large enough to accommodate each of the second magnetic block (2) and the gripper (3). An access point may be, for example, a removed floorboard or an opening drilled behind a skirting board into a floor cavity, through which the second magnetic block and the gripper may be placed into the floor cavity. Such an opening may be a hole to which a wall socket will be later attached. The access points will define the entry and exit points of the portion of the conduit contained within the floor cavity, so their placement should be carefully chosen. In addition, the path to be spanned by the conduit should not intersect with a joist as this would obstruct the conduit laying tool's passage across the underside of the floor (18), so both access points should preferably fall within the span between a single pair of joists.

The gripper (3) may be attached to the end of the cable (20) to be laid, and the grub screw (12) tightened to ensure that the cable is securely fastened within the gripper.

The second magnetic block (2) is then inserted into the floorcavity (17) via a first access point (15), and the first magnetic block 11) is passed over the floor surface (18) close to the first access point to attract the second magnetic block until it is lifted against the underside of the floor by magnetic attraction to the first block. Wide, disc-shaped, powerful neodymium magnets (5) are selected for the two Hocks to ensure a powerful magnetic attraction between them that is sufficient to lift the second block up inside the floor cavity (17) and to hold it securely against the underside of thick floorboards.

However, in light of the small access point apertures and confined spaces through which the second block may need to pass, the dimensions of the blocks are selected to ensure that they maybe passed through reasonably small spaces. In preferred embodiments, the first block (1) has a diameter between 20 and 100mm (and preferably between 25 and 50 mm), a thickness between 10 and 50mm. and a nominal magnetic pull between 10 and 50 kg, while the second block (2) has a diameter between 20 and 50 mm, a thickness between 5 and 25 mm, and a nominal magnetic pull between 5 and 50 kg. In one embodiment, the first and second blocks have respective nominal magnetic pulls of 15 kg and 7 kg, and each has a diameter between 30 and 40 mm. In preferred embodiments, the gripper has a diameter between 15 and 50mm (and preferably between 20 and 30 mill) and a length between 25 and 75 mm (and preferably between 40 and 60 mm).

The first block (1) is then drawn by hand along the floor surface, dragging the second block (2) with it by magnetic attraction, as shown in Figure 2, until they reach the second access point (16). The tether (4) has a length that exceeds the distance between the two access points, so that the second magnetic block may be drawn to the second access point without the gripper (3) entering the first access point. This means that even if the gripper slips free of the cable end or the second magnetic block loses its magnetic coupling with the first block (e.g. due to an under-floor obstruction), at least one end of the tether and/or conduit may be pulled at anytime to retrieve the second magnetic block, gripper and/or cable end without leaving any part of the conduit-laying tool or cable stranded under the floor. Upon alTival at the second access point (16), the second block (2)is retrieved from the floor cavity (17) by magnetic attraction to the first block (1), or by reaching into the floor cavity and retrieving it manually.

The tether (4) is then pulled from the second access point (16) and the gripper (3) eitherrnanually inserted or pulled by the tether through the first access point (15) and into the floor cavity (17). By hoisting on the tether from the second access point, the gnpper and cable end are pulled along inside the floor cavity, feeding the cable (20) in at the first access point. Eventually, the gripper is pulled out of the second access point and the grub screw (12) loosened to release the cable end. The cable now spans both access points via the floor cavity, and its ends may be connected to wall socket terminals or other fittings as desired.

Even if the grub screw (12) were tightened hard enough to damage the cable end, it would be a simple matter to afterwards cut and tn in the cable by a few centimetres or less with cable pliers to remove any damaged portion of the cable. This is generally a dramatically quicker, simpler and more convenient task than fishing around in the floor cavity for a lost cable in the case that a less secure fixation means (such as a knot tied in the end of the tether or an end loop through which the cable end is twisted) had been used instead of the gripper and had come loose while being hoisted under the floor.

Given the uneven nature of floorboards (and the fact that when travelling between a pair of joists, the second magnetic block will generally be traversing the edges of the floorboards) it is important that the second magnet block (2) cannot be stopped by the protruding edges of uneven floorboards. The low friction surface finish and smooth shape of the second block, which is approximately an oblate spheroid, help to ensure that it can glide over uneven floorboard edges without beconii ng lodged or trapped inside the floor cavity. The same curvature and surface finish are also preferred features of the first block (1), to aid its passage across the floor surface.

When the first and second blocks collide, for example when stored together or during retrieval of the second block (2) from the second access point (16), they maybe difficult to pnse apart due to the strength of the magnets used. The convex curvatures of the blocks therefore provide an additional benefit in facilitating the insertion of a tool or lever to prise the blocks apart, and/or by allowing them to be rocked apart by squeezing them together at one periphery of the convex disc shapes and then prising them apart by hand at an opposite periphery. Preferably, a spacer block or ring may be inserted between the magnetic blocks during storage to keep them apart by a distance that permits them to be easily separated by hand.

The gripper (3) also has a smoothly contoured shape and a low-friction finish to permit it to be tugged smoothly through confined spaces without becoming trapped. In the embodiment shown, it has the bullet-like shape of a truncated prolate spheroid and is injection moulded from high density polyethylene. The channel (10) into which the cable is inserted is offset from the centre of the gripper to provide a maximal thickness of plastic for supporting the grub screw (12).

As a variant method of laying the conduit, attachment of the gripper (3) to the conduit end may be done once the second block (2) has been drawn under the floor (20) to the second access point (16) and the tether (4) spans both access points (15, 16).

In other embodiments, the gripper is made of steel and can optionally be drawn along beneath the floor surface using the first magnetic block to aid its passage. or alternatively is integral to the second magnetic block or secured to it without an intervening tether.

The above embodiments are described by way of example only. Many variations are possible without departing from the scope of the invention as defined in the appended claims.

Claims

<claim-text>CLAIMSI. An apparatus for laying conduit, the apparatus having a first mass comprising a ferromagnetic material, a second mass comprising a ferromagnetic material, and a gripper secured to the second mass and adapted to releasably grip an end of a conduit, wherein at least one of the first and second masses comprises a magnet.</claim-text> <claim-text>2. An apparatus for laying conduit according to claim 1 wherein the gripper is secured to the second mass by a flexible tether.</claim-text> <claim-text>3. An apparatus for aying conduit according to claim 2 wherein the tether has a length of at least one metre.</claim-text> <claim-text>4. An apparatus for laying conduit according to any preceding claim wherein at least one of the first and second masses comprises a permanent magnet.</claim-text> <claim-text>5. An apparatus for laying conduit according to any preceding claim wherein at least one of the first and second masses comprises a neodymium permanent magnet.</claim-text> <claim-text>6. An apparatus for laying conduit according to any preceding claim wherein at least 1 5 one of the first and second masses is substantially disk shaped.</claim-text> <claim-text>7. An apparatus for laying conduit according to any preceding claim wherein at least one of the first and second masses has chamfered or rounded edges.</claim-text> <claim-text>8. An apparatus for thying conduit according to any preceding claim wherein at least one of the first and second masses is substantially ellipsoidally shaped.</claim-text> <claim-text>9. An apparatus for laying conduit according to any preceding claim wherein at least one of the first and second masses is substantially shaped as an oblate spheroid.</claim-text> <claim-text>10. An apparatus for laying conduit according to any preceding claim wherein at least one of the first and second masses comprises a housing substantially encasing a ferromagnetic material - 11. An apparatus for laying conduit according to claim 10 wherein the housing is formed of plastic.12. An apparatus for laying conduit according to any preceding claim wherein at least one of the first and second masses comprises a smooth surface formed from a low-friction material.13. An apparatus for laying conduit according to any preceding claim wherein the gripper has a streamlined, convex outer surface.14. An apparatus for laying conduit according to any preceding claim wherein the gripper is substantially bullet-shaped.15. An apparatus for laying conduit according to any preceding claim wherein the gripper is substantially ellipsoidally shaped.16. An apparatus for laying conduit according to any preceding claim wherein the gripper is shaped as substantially a truncated prolate spheroid.17. An apparatus for laying conduit according to any preceding claim wherein the gripper comprises an aperture for receiving an end of a conduit and a screw operable to grip a conduit against a surface of the aperture.18. An apparatus for laying conduit according to any preceding claim wherein the gripper comprises a clamp.19. An apparatus for laying conduit according to any preceding claim wherein the gripper comprises a low-friction material.20. An apparatus for laying conduit according to any preceding claim wherein the gripper is substantially formed of plastic.21. An apparatus for laying conduit according to any preceding claim wherein the gripper is adapted to receive an dectrical cable.22. An apparatus for laying conduit according to any preceding claim wherein the gripper is adapted to receive a pipe.23. An apparatus for laying conduit substandally as herein described with reference to the appended figures.24. A method of laying a conduit through a space covered by a surface including the steps of: providing an apparatus for laying conduit according to any preceding claim, attaching an end of a conduit to the gnpper, passing the second mass into a space covered by a surface, placing the first mass against the surface on the outside of the covered space to draw the second mass against the surface inside the covered spaceby magnetic attraction, and drawing the first mass along the surface so that the second mass is also drawn along the surface by magnetic attraction.25. A method of laying a conduit according to claim 32, when dependent on claim 2, including the steps of retrieving the second mass from the covered space and pulling on the tether to draw the gripper and conduit through the covered space.26. A method of laying a conduit according to claim 33 or 34 wherein the conduit is an electrical cable.27. A method of laying a conduit according to claim 33 or 34 wherein the conduit is a pipe.28. A method of laying a conduit substantially as herein described with reference to the appended figures.</claim-text>