The invention relates to a coupler for conduits with inner ducts. More particularly, ihe invention relates to a coupler for conduits with inner ducts that are adhered in a constant plane to the inner surface of the main conduit.
Background of Invention
Fiber optic cables are widely used as a substitute for much of the copper wire heretofore used in the telecommunications industry, and are often preferred over traditional copper wires in that they are capable of transmitting a substantially greater amount of information while occupying a substantially smaller amount of space. These cables are typically encased in a polyethylene sheath that acts as a protective coating for the fiber optic elements that are formed from glass.
The cables are installed in conduits buried in the ground, or in ducts that have been placed in existing typically subterranean conduits. The inner ducts are used to provide for substantially tow friction placement of, and a hazardless environment for the fiber optic cables. The inner ducts also provide scope for future expansion of networks.
The use of inner ducts for faying cables is known in the art and has been described in documents, for example US 4565351.
On account of various limitations including uneven ground surface, bends, long stretches of cable laying requirements and manufacturing limitations, it is necessary to join two stretches of conduit, and where applicable the ducts within the conduits, together. Couplers, or split couplers as they comprise of two parts that are joint together, are used for this purpose.
Couplers are a!so applicable in the event of conduit, duct or cable repair, as part of the conduit, duct or cable that has been damaged may be replaced and the same may be connected to the existing length by using couplers.
Referring initially to figures 1,2 and 3 a conventional coupler and its application in joining two lengths of a conduit is schematically illustrated.

Figures 1A and 1B illustrate two parts of a coupler (10,11) that are used to receive the two lengths of a conduit. The coupler parts may have one or more flange (12) and may have a provision for fastening means (13) on the flange, such as a nut and bolt. The two parts of the coupler when fastened together define a hollow space (14) in between, such that the hollow space corresponds with the diameter of the conduit, thereby providing an airtight joint.
The coupler parts have a mouth at both ends (15,16) and the two lengths of conduit (17,18) are received in the coupler through these openings, as illustrated by figure 2a and 2b. The inner ducts (19,20) in the conduit are joined using connectors as shown in Figure 3.
It has been discovered, however, that the process of installing a duct within a conduit or main duct poses certain difficulties, particularly when the conduit contains existing duct or cable, a process called an override. The existing duct or cable within the conduit generally exists in a loose and undefined manner, causing new duct to become entangled with the existing duct or cable. Due to this difficulty, inserting a duct into a conduit containing existing cable or duct can be time consuming and in some cases, the insertion of the duct may be limited to short lengths of conduit.
Moreover, installation of cable within a duct that lies in a loose and undefined manner is demanding and requires greater effort.
To address this limitation, the applicant's co-pending patent application No 2045/del/2006 provides for a conduit with an inner duct in which the inner duct is fixed to the conduit over at least a certain portion. More preferably, the inner duct is fixed to the conduit in substantially the same plane.
An example of such a conduit, where the two lengths of the conduit to be joined (30,34) with inner ducts (31,35) fixed to the inner surface of the conduits in substantially the same plane, is illustrated in figure 4.
However, on account of the inner duct being fixed to the conduit wall it is difficult, if not impossible to join the inner ducts using connectors, on account of interference with the conduit inner wall.

There is therefore a requirement for a coupler that can provide an adequate joint for a conduit having inner ducts, in which the inner ducts are fixed to the inner surface of the conduit.
The invention provides for a coupler for joining two lengths of conduit comprising of at least a first part and a second part wherein the first part has a mouth at both ends to receive the two lengths of conduit and is substantially hollow between the mouth at both ends and the second part has a mouth at both ends to receive the two lengths of conduit and includes a central filling between the mouth at both ends, the central filling being capable of receiving a duct placed within the conduit.
Brief Description of the Accompanying Drawings:
The. accompanying drawings illustrate the preferred embodiments of the invention and together with the following detailed description serve to explain the principles of the invention.
Figures 1a and 1b illustrate two parts of a coupler as provided by prior art.
Figures 2a and 2b illustrate joining of two lengths of conduit using a coupler as provided by the priof art
Figure 3 illustrates the joining of inner ducts of the conduit provided by figure 2.
Figures 4a and 4b illustrate a conduit with an inner duct adhered in a constant plane.
Figure 5a and 5b illustrate a coupler in accordance with an embodiment of the invention.
Figure 6 illustrates the use of a coupler as provided by an embodiment of the invention to join inner ducts.

Figure 7 illustrates the application of a coupler as provided by an embodiment of the invention to conduits with inner duct adhered in a constant plane.
Figure 8 illustrates the assembly of the coupler with the conduit in accordance with an embodiment of the invention.
Detailed description of the invention
For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.
It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be restrictive thereof.
Through out the patent specification, a convention employed is that in the appended drawings, like numerals denote like components.
With reference to figure 5 a coupler in accordance with an embodiment of the invention is illustrated. As shown the coupler, as before, comprises of two parts (10', 11') that may be joined together along their flange (12').
The first part of the coupler (10') has mouth (15', 16') at both ends to receive the two lengths of the conduit to be joined The first part (10') also has a hollow central portion
The second part of the coupler (11') also has mouth (15\ 16') at both ends to receive the two ends of the conduit to be joined. The second part has a central filling (32), instead of being hollow, which may be in the form of a molding. The

filling (32) is at a distance from the mouth (15', 16') so as to allow the conduit to enter the coupler.
As also illustrated in figure 5b, the filling (32) has an opening (33) that extends through the length of the filling. The opening is sized so as to allow the inner duct to enter the opening (33) from either end.
The insertion of the inner duct (31) into the opening (33) has been illustrated in figure 6. The mouths (15\ 16') of both the first and second part of the coupler receive the conduit lengths (30, 34), whereas the inner ducts (31, 35) are received by the opening (33) from both end of the filling (32).
When the two parts of the coupler are joined, as illustrated in figure 8, a seal is provided, that is easy and quick to install. Moreover, the coupler allows the joining of conduits with an inner duct fixed to one surface of the conduit and in the same plane.
The coupler as provided, can accommodate conduits with inner ducts loosely defined, as well as conduits with inner ducts adhered in a constant plane.
Though the illustrations depict the filling to be solid and covering the entire central portion of one part of the coupler, it is within the scope of the invention to have a filling in the form of a hollow pipe that is capable of receiving the inner duct from either end. The filling in the preferred embodiment is molded along with the coupler.
Furthermore, the coupler in accordance with an embodiment of the invention has been described to comprise of two parts. However, it is within the scope of the invention to have the coupler comprise of more than two parts that may be joined together with at least one of the parts having a central filling.
It will readily be appreciated by those skilled in the art that the present invention is not limited to the specific embodiments herein shown. Thus variations may be made within the scope and spirit of the accompanying claims without sacrificing the principal advantages of the invention.

We Claim:
1. A coupler for joining two lengths of conduit comprising of at least a first
part and a second part wherein the first part has a mouth at both ends to
receive the two lengths of conduit and is substantially hollow between the
mouth at both ends and the second part has a mouth at both ends to
receive the two lengths of conduit and includes a central filling between
the mouth at both ends, the central filling being capable of receiving a duct
placed within the conduit.
2. A coupler as claimed in claim 1 wherein the filling has an opening that
receives the inner duct.
3. A coupler as claimed in claim 1 wherein the first and second parts of the
coupler have flanges.
4. A coupler as claimed in claim 1 wherein the flanges are provided with
fastening means.
5. A coupler as claimed in claim 1 wherein the central filling is molded with
the coupler.
6. A coupler substantially as herein described with reference to and as
illustrated by figures 5, 6, 7 and 8 of the accompanying drawings.
Dated this 1gth Day of December 2006
Of Anand and Anand Agent for Applicant