WO2005045294A2

WO2005045294A2 - Duct unit for housing service cables, pipes and the like

Info

Publication number: WO2005045294A2
Application number: PCT/ZA2004/000019
Authority: WO
Inventors: Barry Howard
Original assignee: Barry Howard
Priority date: 2003-02-22
Filing date: 2004-02-23
Publication date: 2005-05-19
Also published as: WO2005045294A3

Abstract

A duct unit (1) of channel shape in cross-section is provided that is adapted to cooperate with an identical duct unit to form a closed duct therewith. The duct unit has a closing surface in the form of a rebate or groove (7) extending along one longitudinal edge (2) thereof and a closing surface in the form of a co-operant lip or tongue (6) extending along the other longitudinal edge (3). The closing surfaces of the two opposite edges of two duct units thus cooperate operatively to form an effective closure of the composite duct. The duct unit has at least two spaced catch formations (8, 9) offset radially outwards from the adjacent closing surface and spaced apart along each edge of the duct unit with diagonally opposite catch formations being configured so the one (8) operatively receives the other (9) with a clipping action. The catch formations also serve to locate the one duct unit axially relative to a co-operant duct unit. The duct unit is preferably injection moulded of plastics material as one integral piece.

Description

DUCT UNITS AND DUCTS EMBODYING SAME FOR HOUSING SERVICE CABLES, PIPES AND THE LIKE

FIELD OF THE INVENTION

This invention relates to duct units adapted to be utilized ^"m end-to-end relationship to form elongate duct assemblies for housing cables, pipes and the like whereby services such as electricity, communications facilities and fluids such as liquids, in particular water, and fuel gas are reticulated to various places within a predetermined building, complex, or geographic area.

The cables or pipes could be underground cable or pipe installations or above ground installations in industrial and commercial buildings. The composite duct that houses the cables or pipes can afford protection against physical damage, chemical or corrosive damage, as well as enabling such cables and pipes to be neatly arranged in a manner facilitating maintenance, repair and even replacement of the cables or pipes or sections thereof.

BACKGROUND TO THE INVENTION

The advantages of housing cables and pipes in ducts for the various purposes outlined above have long been recognized and various forms of such ducts have been proposed. Some of the advantages are more fully set out ϊn my published international patent application number PCT ZA01/00204 published under international publication number WO 02/054553 A2, and the content of which is included herein by reference.

Some of the prior art proposals are also set out in my published international patent application identified above; British patents 2,276,694; 2,339,66; and

2260590 as well as German patent 1,681,159. AH of these describe a duct Ϊ two opposed semicircular cross-sectioned channels the edges of which are engaged with each other to form a duct to enclose cables or pipes therein. The channels are held in their operative relationship with each other by means of clamps or straps that encircle the resultant duct. Uttle, if anything, is disclosed concerning the sealing of the lengths of channel to each other and the end on end connection of lengths thereof.

International publication number WO 9S/45915 describes an arrangement in which a semicircular cross-sectioned channel shaped duct unit has co- operant tongue and groove formations extending along the two free edges such that two identical units can have their co-operant edges inter-engaged with each other with the tongues of the formations along one edge clipping into the grooves of the formations along the other edge. This arrangement does not, however, provide any particular way in which the ends of the two units can be aligned. Also, appreciable force is required to engage and disengage tongues and grooves as they extend along the entire length of the duct units.

OBJECT OF THE INVENTION

It is, accordingly, an object of this invention to provide a duct unit and assemblies of duct units in which the drawbacks identified above may be diminished, at least to some extent.

SUMMARY OF THE INVENTION

In accordance with this invention there is provided a duct unit of channel shape in cross section and adapted to cooperate with an identical duct unit to for a closed duct therewith, the duct unit having a closing surface in the form of a rebate or groove extending along one longitudinal edge thereof and a closing surface in the form of a co-operant lip or tongue extending along the other longitudinal edge such mat the closing surfaces of two opposite Λ units cooperate operatively to form an effective closure of the duct along the two pairs of cooperating dosing surfaces, Hhe duct unit being characterized in that it has at least two spaced catch formations offset radially outwards from the adjacent closing surface and spaced apart along each edge of the duct unit with diagonally opposite catch formations being configured so mat one operatively receives the other with a clipping action and wherein the catch formations further serve to locate the one duct unit axϊaliy relative to a co-operant duct unit

Further features of the invention provide for the catch formations to be formed integral with the duct unit, typically by forming the duct unit as a single piece injection moulding of suitable plastics material such as an appropriate polypropylene material; for the catch formations to be formed one as a channel having a catch or a slightly inwardly tipped configuration in which case a cooperant catch formation has a cross-sectional shape complementary to that of the channel, typically a generally rod shape; and for the two ends of the duct unit to be formed as a male spigot and female socket respectively adapted to form a complete spigot or socket together with a cooperant duct unit that forms a closed duct therewith with the male end being adapted to be accommodated within the female end of a coaxially arranged similar duct unit.

Preferably, the male end of the channel shaped part has a peripheral flange extending at least a part way around the end of the duct unit i which case the female end has a cooperating groove to accommodate the peripheral flange such that, in the closed position, the flange and groove serve to angularly align two coaxial interconnected duct unite. The arrangement of the spigot and socket is preferably such that the internal diameter of a joint between two coaxial duct units remains constant across the joint. This arrangement enables cables and the like to be drawn through the duct without any interference that could be caused by a small step change in internal diameter. Also, the outer surface of the duct unit can have both longitudinal and circumferential reinforcing ridges moulded integral therewith.

In order that the above and other features of the invention may be more fully understood one embodiment thereof will now be described with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective illustration of one embodiment of the invention showing one pair of duct units cooperating to form a closed length of duct and a colliπear pair in the open condition; Figure 2 ϊs an end view of two duct units in exploded relationship relative to each other;

Figure 3 is a plan view of part of the length of a duct unit showing two pairs of diametrically opposite catch formations and the spigot and socket formations at the end thereof;

' Figure 4 ϊs a detailed perspective view of the on type of catch formation; and, Figure 5 is a detailed perspective view of the other type of catch formation.

DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS

In this embodiment of the invention a duct unit, generally indicated by numeral (1), is made as a single piece plastics injection moulding having the and diameter. Typically the length could be of the order of about a metre and the diameter can be as required, typically from 50 to 300 mm although for illustration purposes, a very much shorter duct unit is illustrated.

The duct unit ϊs formed as a single channel shaped part of semicircular Shape in cross-section such that ϊt has two longitudinal free edges (2) and (3) and two semicircular ends (4) and (5) (see Figure 1).

the one free edge (2) of the duct unit has a longitudinally extending sealing lip (6) the transverse dimension of which is directed in a generally circumferential direction and that is operatively sealiπgly received in a cooperant rebate (7) in the other free edge (3) (see in particular Figure 2). The lips and rebates can be made to effectively close the duct and the degree of sealing achieved can be selected according to requirements and according to the materials of manufacture as well as the strength of the catch formations described below.

In this illustrated embodiment of the invention the duct unit has two catch formations (8) and (9) at corresponding diametrically opposed positions on the outside of the edges (3) and (2) respectively. The catch formations are symmetrically spaced apart along the length of the duct unit; are integral with the duct unit; and our radially outside of the edges (3) and (2) The one form of catch formations (8) associated with the one edge (3) each assume the form of a channel that may either be inwardly lipped or have an integral catch member (10) serving as a closure for the catch formation. The other form of catch formations (9) that are associated with the opposite edge (2) are rod tike ϊn general configuration to present a complementary surface to the channel shaped catch formations (8). The catch formations have corresponding lengths and thus, when inter-engaged with the co-operant catch formations of another duct unit to form a complete duct, the catch formations serve not only to securely attach the duet units together in a radial to locate them longitudinally relative to each other. End on end attachment of lengths of duct is provided for by forming a male spigot (10) and female socket (11) at the two ends (4) and (S). As indicated above, the ends are preferably provided with cooperant flange (12) and groove (13) formations to ensure that collϊnear lengths of duct remain angularly aligned.

Also, as indicated above, the injection moulded duct unit can be reinforced with both circumferential external ribs (14) and longitudinally extending external ribs (15).

In use, an elongate duct assembly can easily be made up from a series of coaxial duct units of the type described above, A collinear series of duct units can be laid along a required path and any desired cables pipes or other elongate service elements installed therein. The co-operant duct units are then clipped into position in cooperating relationship with those laid on the required path to close the duct.

It will be understood that numerous variations may be made to the embodiment of the invention described above without departing from the scope hereof. Also, it will be understood that, as described in my earlier international patent application identified above, various junction and terminal fittings can be produced to cooperate with duct units provided by this invention.

Claims

CLAIMS;

1. A duct unit (1) of channel shape cross-section and adapted to cooperate with an identical duct unit to form a closed duct therewith, the duct unit having a closing surface in the form of a rebate or groove (7) extending along one longitudinal edge (2) thereof and a closing surface ϊn the form of a co-operant lip or tongue (6) extending along the other longitudinal edge (3) such that the dosing surfaces of two opposite edges of two duct units cooperate operatively to form an effective closure of the duct along the two pairs of cooperating closing surfaces, the duct unit being characterized in that it has at least two spaced catch formations (8, 9) offset radially outwards from the adjacent closing surface and spaced apart along each edge of the duct unit with diagonally opposite catch formations being configured so that one (8) operatively receives the other (9) with a clipping action and wherein the catch formations further serve to locate the one duct unit axially relative to a co-operant duct unit

2. A duct unit as dai ed in daim 1 in which the catch formations are formed integral with the duct unit.

3. A duct unit as claimed in daim 2 in which the catch formations are formed one as a channel (8) having a catch or a slightly inwardly lipped configuration ϊn which case a cooperant catch formation has a cross- sectional shape complementary to that of the channel and of a generally rod shape (9).

4. A duct unit as daimed in any one of the preceding claims 2 in which the duct unit is a single piece injection moulding of suitable plastics material.

5. A duct unit as daimed ϊn any one of the preceding daims ϊn which the two ends of the duct unit are formed as a male spigot (10) and female socket (11) respectively adapted to form a complete spigot or socket together with a cooperant duct unit that forms a dosed duct therewith with the male end being adapted to be accommodated within the female end of a coaxially arranged similar duct unit.

6. A duct unit as claimed in claim 5 in which the male end of the channel shaped part has a peripheral flange (12) extending at least a part way around the end of the duct unit in which case the female end has a cooperating groove (13) to accommodate the peripheral flange such that, in the dosed position, the flange and groove serve to angularly align two coaxial interconnected duct units.

7, A duct unit as claimed in either one of daims 5 or 8 in which the spigot and socket are such that the internal diameter of a joint between two coaxial duct units remains constant across the joint,

8. A duct unit as daimed in any one of the preceding claims in which the outer surface of the duct unit has both longitudinal and drcumfereπtϊal reinforcing ridges (14, 15) moulded integral therewith.