Implements or apparatus for applying pushing or pulling force – Method or apparatus for placement of conductive wire – By fluid pressure differential in conduit
Reexamination Certificate
1999-09-17
2001-07-24
Watson, Robert C. (Department: 3723)
Implements or apparatus for applying pushing or pulling force
Method or apparatus for placement of conductive wire
By fluid pressure differential in conduit
Reexamination Certificate
active
06264170
ABSTRACT:
BACKGROUND
The Present invention relates to a method and apparatus for cleaning of and insertion of a draw line in a conduit and particularly small to medium sized conduits. The method is applicable for insertion of draw lines in a wide variety of conduits including water and electrical conduits. It will be appreciated that the application of the invention should not be limited to the types of conduit specifically mentioned by way of example.
PRIOR ART
Insertion of draw lines in small to medium sized conduits has been a problem for some time. It has in the past proved particularly difficult to insert cables in conduits of small diameter for example electrical conduit especially where those conduits include bends. Electricians very often are required to feed electrical cable through small diameter conduits having awkward 90° and 120° bends causing bending or bunching of the cable at the bends. Previously, to overcome this problem, feeding had to be done piece by piece using separate and detachable bend fittings.
Ideally, insertion of the cable in a conduit is best effected by pulling the cable through a conduit rather than pushing it through, but the former can only be effected if a drawline is inserted into the length of conduit from an inlet to an outlet end but achieving this is difficult particularly where the pipe network includes bends as is usually the case with electrical conduits. The same problem occurs in any pipe network system such as in water or gas pipes where they may need to be internally cleaned. It is infeasible to push cleaning probes into pipes particularly those of narrow diameter as they become jammed and often cannot be retrieved. Also, where the network includes sharp bends it is not possible to clean the pipe network from beginning to end and throughout the network due to the extreme difficulty in inserting cleaning cloths or analogous cleaning apparel inside a conduit.
INVENTION
In one form, the present invention provides an assembly for air assisted insertion of a draw line or the like through a conduit or pipe network of conceivably almost any length. The assembly according to one embodiment generally includes;
a pneumatic gun which regulates the flow of pressurised air from an air source, a spool unit including a chamber for receiving and holding a spool of string, and guide means to guide the string from said chamber into said conduit via said pneumatic gun. The assembly according to the invention provides a convenient, quick and efficient, cost effective method for insertion of a draw line in a conduit. The assembly is ideally suited for small diameter conduits such as those in the 10-100 mm range and particularly those including bends, where it would normally be difficult to feed a cable through the conduit or (where the conduit or pipe is to be cleaned), to insert cleaning cloth or like apparel into the pipe.
In one broad form the present invention comprises;
an assembly for providing air assisted insertion of a draw line such as a string line or the like in and through a conduit or network of conduits; the assembly including;
a pneumatic gun with a housing having an internal chamber having an entrance and an exit, a handle attached to or integral with said housing and having a bore therethrough in communication with said internal chamber, and at an entrance to said bore coupling means to facilitate receipt of pressurised air from a pressurised air source;
a spool unit integrally or detachably connected directly or indirectly to said pneumatic gun and which receives and retains therein a draw line spool or cartridge, said spool unit including an internal chamber which terminates in an opening in communication with the internal chamber of said pneumatic gun and through which a line on said line spool travels; wherein, upon actuation of a trigger on the pneumatic gun, pressurised air from the air source urges the draw line through the gun and upon exiting said internal chamber into the conduit.
Preferably, the assembly includes a line guide at least partially located in a bore of the gun and within the internal chamber and which guides the line through the gun until it enters the conduit. The spool unit is either integrally or detachably connected to the line guide which in turn is fitted to the gun. The pressurised air supply is delivered via a hose through the handle of the gun and into the bore such that it passes about the line guide and urges the line as it exits the line guide along the conduit. A pellet or line traveller is tied at the leading end of the draw line which guides the draw line through a conduit in which it is injected. The gun also preferably includes a head assembly which receives an adaptor having an orifice of a predetermined size selected according to the diametric size of the pipe in which the line is to be placed. Thus an end of the adaptor will ideally have an external diameter less than the internal diameter of a pipe in which the draw line is to be inserted.
In an alternative form the present invention comprises;
a line guide for use with an assembly for air assisted insertion of a draw line in a conduit, the line guide comprising:
a generally elongate body having a leading end and a trailing end, wherein the leading end includes a tubular member having a bore therethrough and wherein the trailing end comprises means to enable connection of said line guide to a pneumatic gun, and means to enable connection of a spool unit to said line guide each said means having a through passage in communication with said bore through which a draw line is fed.
In another form of the apparatus aspect the invention comprises; a spool unit for use with an assembly for air assisted insertion of a draw line in a conduit; the unit including a generally cylindrical body, defining an internal chamber, a shaft mounted on the body and inside said chamber and which receives and supports a line carrying spool; means on the body enabling connection of the body either directly or indirectly to a pneumatic gun, such that the internal chamber communicates via an opening through which the line exits, with a bore inside a line guide inserted inside the pneumatic gun; and further including a braking assembly to control the degree of rotation of the spool upon actuation of the air assisted insertion assembly.
According to a preferred embodiment the chamber comprises a detachable cover which allows access to the inside of the chamber for insertion of the spool.
According to a preferred embodiment the spool unit comprises first and second body parts each of which include a generally cylindrical skirt formation having a free end defining an opening and an opposite end wall, wherein an axle or shaft is attached to said end wall of one or other of said body parts, said axle receiving and retaining a line spool for rotation about said axle, each said skirt formations including corresponding mating profile parts which enable opposing engagement of said first and second body parts so as to form said spool unit.
Preferably, the spool unit comprises a braking assembly including a braking member biased so as to bear against a spool flange or wall when the spool is inserted inside the chamber defined by engagement of the first and second body parts, said braking member comprising; a disc mounted on a shaft, a first end of which engages in axial alignment with a free end of the axle of a first body part and the second end of which engages and is supported by the end wall of the second body part, a fibre ring disposed about the periphery of the disc adapted to engage under the action of said bias the wall of a spool inserted in said chamber.
The first body part also includes a fibre ring which engages an opposite wall or flange of the spool to regulate rotation thereof. In an alternative embodiment, the second element further includes means to increase or decrease the level of said bias to thereby adjust the level of braking of rotation of said spool.
According to a method aspect the present invention comprises; a method for air assisted insertion of a draw line i
Lowe Hauptman & Gilman & Berner LLP
Pneumatic Systems International Pty., Ltd.
Watson Robert C.
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