HK1020232A - Method and assembly for cleaning and/or insertion of a draw line in a conduit - Google Patents

Description

Method and apparatus for cleaning a pipe and/or inserting a pull cord into a pipe

The present invention relates to a method and apparatus for cleaning the inside of a duct and/or inserting a pull cord into a length of duct, and to a convenient and effective method of sealing the end of a duct for facilitating said insertion of said pull cord, the leading end of which is fed through the duct by an air assist shuttle attached to said leading end.

Today, telecommunication cables are often laid in specially constructed cable trenches in the ground. To protect the cable from possible damage by water, debris and insects, telecommunication cables are generally laid inside plastic (usually polyvinyl chloride, PVC) pipes. Thousands of kilometers of such cables have been laid in underground pipelines, but due to the rapid development of telecommunications utilities and the need for more cables, it is envisaged that hundreds of thousands of kilometers of cables will be required in the future.

Installed pipes are generally of three types: unoccupied ducts that are ready to wait for receiving a new cable, ducts that are already partially occupied, and ducts that are completely full of cable. The present invention relates primarily to the first and second types of conduits described above. The process of inserting the cable into the conduit is time consuming, labor intensive and therefore expensive. Existing methods of inserting a pull cord into a conduit are slow, cumbersome and inefficient.

To feed a cable through a conduit, it is necessary to insert a pull cord into the conduit and then secure the pull cord to the leading end of the cable so that the cable can be pulled through a length of the conduit end. The pull cord may be inserted and simply placed in the conduit to await the subsequent insertion of the cable. This is helpful to the cable installer because in this case the pull cord is already placed in the conduit prior to installation of the cable, so that the pull cord is easily attached to the leading end of the cable, which is then pulled through the conduit by the pull cord. One prior method of inserting a pull cord into a conduit involves the use of an original umbrella to which the pull cord is attached. The umbrella is inserted into the pipe through the access end. Compressed air is then fed into the umbrella to inflate it, whereupon it exits the duct, with the pull cord also exiting with it. To maintain the required positive air pressure, the inlet end of the pipe must be sealed to prevent air from escaping. This is currently done in the original manner by inserting rags or similar materials into the inlet end of the duct, which must be manually held in place when introducing positive pressure into the duct. The positive pressure is introduced into the conduit through a copper tube connected to a source of compressed air. Rags and other packaging materials surround the copper tubing. The drawstring must be sufficiently free to move through or around the packaging material while compromising the integrity of the seal, resulting in a loss of pressure at the entry end of the tube. In the past, pipe sealing has been a major problem for operators and has been a particular problem when the pipe is filled with water and debris due to back flow. When the pipeline is under pressure and the seal fails, the pressurization may cause water and debris to move to the point of the pipeline inlet end. When the conduit is partially filled with cable, it is difficult to seal the conduit. Another problem that arises with the above-described method is that the umbrella elements present a detrimental fold or bond. The umbrella members currently in use consist essentially of a layer of textile material or the like, to which one end of each multi-length thread is attached at a point on its periphery, the lengths of thread terminating at their other end in a connector which also receives the leading end of a pull cord.

The umbrella is easily folded within the duct, allowing more air to bypass one edge if the air is collected asymmetrically in the umbrella, especially compared to when the bypass is symmetrical in normal operation and the umbrella is balanced properly. This imbalance may cause the umbrella to rotate, causing the connecting wires to become entangled, in which case the wires may become entangled in the air-collecting textile material of the umbrella. This means that the tangled umbrella must be removed from the pipe, and the procedure described adds time and effort to the insertion of the drawstring.

Solving this problem is the subject of the applicant's co-pending application. There are other problems with the prior art devices, such as: the drawstring contacts the user's hand, the copper tubing must be held in place by the operator, and the wrapping rag and foam may be blown out. In addition, two people are typically required in the pipe pit, one to transport the drawstring and the other to secure the copper air line and rag in place.

In another prior art method, push rods may be inserted from both ends of the pipe until they meet at a point midway where the pipe is severed and joined, thus creating a joint through which harmful water may subsequently pass. The push rod can be inserted from both ends up to 100 m. The push rod method is cumbersome and can result in damage to the cables within the conduit, especially in those instances where the narrow V-shaped channel formed when the cables cross within the conduit engages the push rod.

The present invention provides a method and apparatus for cleaning the interior of a conduit and for inserting a pull cord suitable for carrying a cable such as a telecommunications cable into the conduit without undue effort. The present invention also relates to an efficient method of sealing the ends of occupied or unoccupied ducts to facilitate insertion of a pull cord into the duct. The device includes an air-assisted shuttle that pulls a pull-cord through the conduit under positive air pressure. The applicant has made this shuttle the subject of a co-pending application.

According to an apparatus aspect of the present invention there is provided apparatus for cleaning the inside of a duct and/or inserting a pull cord into a duct, comprising a device for sealing the end of a duct into which a pull cord is to be placed, the device, when compressed air is fed into a duct between the device and a shuttle responsive to the compressed air, promoting the leading end of the pull cord being fed through the duct so that the shuttle is advanced along the duct until the pull cord exits the duct with it.

In its most general form, the apparatus aspect of the invention comprises:

a device for air-assisted insertion of a pull cord into a pipe from its inlet end and advancing the cord along the pipe to its outlet end,

the device includes:

a source of compressed air;

a means for sealing the end of said conduit which permits the delivery of compressed air from said air source through or around said sealing means into said conduit;

a through passage in or adjacent said sealing device which receives a pull cord so that when said sealing device engages the entry end of said pipe, the pull cord can enter the sealing device outside or inside the pipe and exit the sealing device inside the pipe; and

a device connected to the leading end of the pull cord, responsive to the delivery of air from said source of compressed air, for advancing the pull cord along the conduit until it exits the conduit through said outlet end.

Preferably, the air source is connected directly or indirectly to the sealing device, and the insertion device further comprises a manifold comprising means for receiving at least one air hose communicating between said compressed air source and said manifold, and the sealing device comprises an inflatable bag responsive to said compressed air such that said inflatable bag expands under said air pressure to seal the end of said conduit.

Preferably, at the forward end of the sealing device, the inflatable bag is positioned around a generally elongate tubular member, wherein a membrane is secured at both ends to the member and is positioned coaxially around it, wherein a chamber is formed between the inside of the membrane and the tubular member which receives compressed air to inflate the membrane and engage the inner surface of the pipe.

The manifold preferably includes at least one air inlet, one air outlet, and a control valve for controlling the flow of air as the air is exhausted.

According to a most general form of the method aspect of the present invention, there is provided a method for inserting a pull cord into a conduit, comprising the steps of:

a) feeding the free end of the pull cord through a passage or opening in a sealing device capable of sealing one end of the conduit;

b) fixing the free end of the pull rope on the shuttle, and inserting the shuttle into the pipeline through the inlet end;

c) sealing the end of the pipe with a sealing device;

d) introducing compressed air into or around said sealing means and into said conduit downstream of said sealing means and upstream of said shuttle;

e) sufficient air pressure is applied to cause the shuttle to move along the conduit until it carries the pull cord out of the conduit.

According to a preferred embodiment, the method further comprises a step of returning the pull cord through the sealing device for removing any slack in the pull cord between the sealing device and the shuttle.

According to another broad form of the method aspect of the invention, the apparatus of the invention comprises:

a source of compressed air;

a means for sealing one end of said conduit which permits compressed air to be delivered from said air source through or around said sealing means into said conduit;

an adaptor channel in or adjacent said sealing device which receives a pull cord so that when said sealing device engages the entry end of said pipe, the pull cord can enter the sealing device outside or inside the pipe and exit the sealing device inside the pipe;

a device connected to the leading end of the pull cord for advancing the pull cord along the conduit in response to the delivery of air from said source of compressed air until it exits the conduit through said outlet end;

the method of the invention comprises the following steps:

a) feeding the free end of the pull cord through a passage or opening in a sealing device capable of sealing one end of the conduit;

b) fixing the free end of the pull rope on the shuttle, and inserting the shuttle into the pipeline through the inlet end;

c) sealing the end of the pipe with a sealing device;

d) introducing compressed air around the sealing device and into the conduit downstream of the sealing device and upstream of the shuttle;

e) inflating an inflatable bag on said sealing apparatus so that the inflatable bag engages the inner surface of said pipe to seal said pipe;

f) sufficient air pressure is applied to cause the shuttle to move along the conduit until it carries the pull cord out of the conduit.

According to another broad form of the method aspect of the present invention, the invention comprises a method of inserting a pull cord into a conduit using an apparatus comprising:

a source of compressed air;

a sealing device for sealing one end of the pipe, which is directly or indirectly connected to a source of compressed air;

a shuttle connected to the pull cord and responsive to the pressurized air;

the method comprises the following steps:

a) feeding the free end of the pull cord through an opening in the sealing device;

b) securing the shuttle to said free end of the pull cord and inserting the shuttle into the conduit through the inlet end;

c) inserting the sealing device into said inlet port after the sealing device has been connected to a manifold that controls the flow of air into the sealing device and the pipe;

d) sealing the end of the pipe by adjusting a control valve on the manifold, and inflating an inflatable bag on the sealing device;

e) the control valve is adjusted to allow compressed air to enter the conduit, thereby activating the shuttle until the shuttle exits the conduit carrying the pull cord.

Preferably, the method includes an additional step of adjusting the control valve after the shuttle exits the conduit to release the sealing device from the conduit.

Preferably, the sealing means comprises a manifold which controls the delivery of air to the conduit connected to the leading end of the manifold and to the sealing means.

In another broad form thereof, the invention comprises an apparatus for cleaning the interior of a pipe using a cleaning element such as a cylindrical block (pellet), the apparatus comprising a means for sealing one end of the pipe and allowing compressed air to be fed into the pipe, the compressed air forcing the cylindrical block through the pipe, thereby forcing water and/or debris in front of it through the pipe.

The invention will now be described in more detail with reference to preferred but not limiting embodiments of the invention in terms of methods and apparatuses, and with reference to the accompanying description thereof.

FIG. 1 illustrates an illustration of a pull cord insertion device in accordance with a preferred embodiment of the present invention;

FIG. 2 illustrates a side view of a manifold similar to that shown in FIG. 1 controlling the delivery of air into the interior of the duct and into the sealing apparatus, in accordance with a preferred embodiment of the present invention; and

fig. 3 illustrates a sealing apparatus according to a preferred embodiment of the present invention.

Referring to fig. 1, there is shown in accordance with a preferred embodiment of the present invention a device 1 for placing a pull cord into a conduit 2. This device may also be used to remove water and/or debris from the interior of the pipe. However, the device will be described substantially only in terms of its use for inserting a pull cord into a conduit. The device 1 comprises a manifold 3 with a sealing device 4, a compressed air source, a shuttle 6 and a pull cord 6 a. The sealing device 4 is preferably detachably fixed to the manifold 3 so that different sizes of sealing devices can be exchanged depending on the size of the pipe to be sealed. Fig. 1 shows the sealing device 4 inserted into the pipe 2, through which the pull cord 6a passes and is connected with its front end to the shuttle 6.

Referring now to fig. 2, the manifold 3 comprises a manifold body 3a having a base 5 at one end thereof, the base 5 receiving a fitting 5a connected to an air supply hose 7 (see fig. 1), the hose 7 in turn being connected to a source of air which may be, for example, a conventional air compressor 8. At or near the same end, the manifold block 3a further includes a base 9, the base 9 housing a fitting 10 connected to an air supply hose 11 (see FIG. 1), the hose 11 in turn being connected directly or indirectly to the air compressor 8.

As shown in fig. 1, the hose 11 sends compressed air to the sealing device 4 through the base 9. The air supply to the sealing device 4 is regulated by a valve 12, the valve 12 being manually operated by an operator to send air to a space 13 (see also figure 3) surrounded by an inflatable bag formed in a flexible membrane 14, the membrane 14 being radially enlarged until it frictionally engages the inner surface 15 of the pipe 2. The seal 4 acts as a plug to seal the end 16 of the pipe 2 and the seal 4 is releasably secured to the manifold body 3a by the connector 17. The sealing device 4 is selected according to the size of the pipe into which the pull cord 6a is to be placed, so that a range of sizes is obtained.

Figure 3 shows a partial cross-sectional view of a typical sealing device 4. The sealing device 4 is a generally tubular member comprising an inflatable bag formed by a flexible membrane 14, the membrane 14 surrounding a cylindrical inner tube 18, thereby forming a cavity or space 13 between the membrane 14 and the tube 18. The membrane 14 is preferably of rubber material and is secured at both ends by clamps 19 and 20. The clamping of the two ends of the membrane 14 ensures that the cavity or space 13 is airtight. The membrane 14 is sufficiently resilient that it can move radially in response to pressurisation of the cavity with compressed air from the air source 8, thereby enabling a tight interfit between the membrane 14 and the inner surface 15 of the pipe 2, with the result that the end 16 of the pipe 2 is sealed so that compressed air introduced into the pipe 2 can only exit through the opposite end of the pipe according to the arrangement shown in figure 1.

Preferably, air introduced into the cavity 13 is fed from the hose 11, through the valve 12 and then into the cavity 13 via one or more apertures 21 and 22 to inflate the air-filled bag formed by the membrane 14 to the required pressure. The operator selects the pressure required to effect a seal against the inner surface 15 of the pipe 2 according to the sealing requirements taking into account the size of the diameter of the sealing device and the radial distance the membrane must travel. Generally, the air pressure that can be used to achieve an adequate seal is in the range of 25 to 150 psi. The pressure may be monitored by a pressure gauge 23. To maintain this pressure when the pull cord 6a is inserted after pressurizing the cavity 13 to the desired degree, the valve 12 is adjusted to seal the compressed air to maintain frictional engagement between the membrane 14 and the inner surface 15 of the pipe 2.

The device is suitable for use in the following aspects described with particular reference to the arrangement shown in figure 1. An operator selects the pipe 2 for inserting the pull cord 6a therein. On site, it is very common for the pipes to have water or debris in them, which is preferably removed. If the conduit is empty, the shuttle 6 can be replaced by a cylindrical block 23, since water and debris can be pushed in front of it as it moves through the conduit. The shuttle 6 can be used when the conduit into which the pull cord is placed is partially full of cable or empty. The shuttle 6 can move some debris to some extent, but the guides or air traps 24 on the shuttle 6 tend to conform to the internal contours of the duct under air pressure and are generally insufficient to push debris in front of the shuttle. In the case of pipes in which some cables have been laid, the section may be uneven; in this case, the air collector may travel on uneven contours. Thus, the operator can select the cylinder block 26 or the shuttle 6 for inserting the pull cord, depending on the state of the conduit (i.e. empty or partially full of cable).

In the case of a cylindrical block, the pull cord is attached to it by end 6 b. According to a method aspect of the invention, the first step is to feed the leading end of the pull cord 6a through the opening 5a in the manifold body 3 a. The leading end 6b is then attached to the shuttle 6 or cylindrical block 23 and fed into the pipe 2 at a short distance. Thereafter, the manifold 3 is secured to the end of the pipe while the pull cord is fed back through the manifold to eliminate undesirable sagging of the pull cord 6 a. When the manifold 3 is assembled, the sealing device 4 enters the pipe 2 and then inflates it, thereby sealing the pipe 2 in the manner described hereinbefore. After closing the valve 12, the manifold is securely fixed in position. Compressed air is then fed into the conduit by further adjusting the valve 12, thereby driving the cylindrical block 23 or shuttle 6 along the conduit until it exits the conduit pulling the pull cord 6 a. The sealing device 4 is then released by opening the valve 12, whereby compressed air is expelled from within the membrane 14. The trailing end of the pull cord 6a is then pulled out of the manifold 3, thereby providing for the securement of a cable to be pulled through the conduit.

The apparatus may also be used to deliver pull cords from a device called a launcher (launcher) which includes a spool of cord to be fed into a pipe.

It will be appreciated by persons skilled in the art that numerous variations and modifications may be made to the invention as broadly described herein without departing from the general spirit and scope of the invention.

Claims (27)

1. An apparatus for air-assisted insertion and propulsion of a pull cord into a conduit from an inlet end to an outlet end along said conduit, the apparatus comprising:

a source of compressed air;

a means for sealing one end of said conduit to allow compressed air to be fed into said conduit from said air source, through or around said sealing means;

a through passage in or adjacent said sealing device which receives a pull cord such that when said sealing device engages the inlet end of said pipe, the pull cord is able to enter the sealing device outside or inside the pipe and exit the sealing device inside the pipe;

a shuttle connected to the leading end of the pull cord is responsive to the delivery of air from the source of compressed air to advance the pull cord along the conduit until the pull cord exits the conduit through the outlet end.

2. The apparatus of claim 1, wherein the air source is directly or indirectly connected to the sealing device.

3. The apparatus of claim 2, wherein the air source delivers air to the sealing device through an air manifold.

4. The apparatus of claim 3, wherein the manifold controls the delivery of compressed air into the conduit.

5. The apparatus of claim 4, wherein the sealing device comprises a generally elongated tubular body including an outer membrane forming an inflatable bag.

6. Apparatus according to claim 5, wherein the membrane forming the inflatable bag is responsive to said compressed air to urge the membrane against the inner wall of the duct to effect a sealing engagement between the inflatable bag and the duct.

7. Apparatus according to claim 6, wherein the membranes are secured to the ends of said tubular body by clamps or the like, one of which is connected to a connector for receiving said manifold.

8. The apparatus of claim 5, wherein the manifold includes at least one air inlet, one air outlet, and a control valve for controlling the flow of air and for exhausting air.

9. The apparatus of claim 8, wherein the control valve moves between: a first position in which compressed air is prevented from entering the manifold, a second position in which air is delivered into the inflatable bag, a third position in which air is delivered into the conduit, and a fourth position in which air is exhausted from the manifold, the conduit, and the inflatable bag.

10. Apparatus according to claim 9, wherein the manifold includes fittings at both inlet ports which receive air supply hoses connected to said source of compressed air.

11. The apparatus of claim 10, wherein the manifold further comprises a fitting at the outlet that mates with the sealing device.

12. The apparatus of claim 11, wherein the manifold further comprises a pressure gauge.

13. The apparatus of claim 12, wherein the shuttle comprises an elongated shaft having at least one inflatable air collector radially disposed therearound.

14. An apparatus according to claim 13, wherein the air collector comprises either a skirt having a waist fixed to said shaft and a free end which moves radially in response to air pressure, or an array of air collection cells disposed radially around said shaft.

15. A sealing device for use with apparatus for inserting a pull cord into a duct, the sealing device comprising a generally elongate tubular member having disposed therearound a flexible membrane clamped at its ends to form an inflatable bag.

16. The sealing apparatus of claim 15, wherein the membrane forming the inflatable bag is responsive to compressed air to urge the membrane against the inner wall of the duct to effect a sealing engagement between the inflatable bag and the duct.

17. A sealing device according to claim 16, wherein the membranes are secured to both ends of the tubular body by clamps or the like, one of which is connected to a fitting for receiving the manifold.

18. A manifold for use with a device for inserting a pull cord into a conduit, wherein the manifold comprises at least one air inlet, one air outlet, and a control valve.

19. A manifold according to claim 18, wherein the control valve moves between: a first position in which compressed air is prevented from entering the manifold, a second position in which air is delivered into an inflatable bag connected to the sealing apparatus, a third position in which air is delivered into the conduit, and a fourth position in which air is exhausted from the manifold.

20. A manifold according to claim 19, wherein the manifold comprises fittings at both inlet ports, the fittings receiving air supply hoses connected to said source of compressed air.

21. A manifold according to claim 20, further comprising a fitting at the outlet for mating with the sealing device.

22. The apparatus of claim 21, further comprising a pressure gauge.

23. A method of inserting a pull cord into a conduit and moving it along the conduit using an apparatus comprising:

a source of compressed air;

a means for sealing one end of said conduit to allow compressed air to be fed into said conduit from said air source through or around said sealing means;

a through passage in or adjacent said sealing device which receives a pull cord such that when said sealing device engages the inlet end of said pipe, the pull cord is able to enter the sealing device outside or inside the pipe and exit the sealing device inside the pipe;

a device connected to the leading end of the pull cord for advancing the pull cord along the conduit in response to the delivery of air from said source of compressed air until the pull cord exits the conduit through said outlet end;

the method comprises the following steps:

a) feeding the free end of the pull cord through a passage or opening in a sealing device capable of sealing one end of the conduit;

b) securing the free end of the pull cord to the shuttle and inserting the shuttle through the access end into the conduit;

c) sealing the end of the pipe with a sealing device;

d) introducing compressed air around the sealing apparatus and into the conduit downstream of the sealing apparatus and upstream of the shuttle;

e) inflating an inflatable bag on the sealing apparatus such that the inflatable bag engages the inner surface of the pipe, thereby sealing the pipe;

f) sufficient air pressure is applied to urge the shuttle along the conduit until the shuttle exits the conduit carrying the pull cord.

24. The method of claim 23, further comprising the step of returning the pull cord to eliminate any sagging in the pull cord between the seal and the shuttle.

25. A method of inserting a pull cord into a conduit using a device comprising:

a source of compressed air;

a sealing device for sealing one end of the pipe, which is directly or indirectly connected to a source of compressed air;

a shuttle connected to the pull cord and responsive to the pressurized air;

the method comprises the following steps:

a) feeding the free end of the pull cord through an opening in a sealing device;

b) -securing a shuttle at said free end of the pull cord and inserting the shuttle into the conduit through the access end;

c) inserting the sealing device into said access port after connecting the sealing device to a manifold that controls the flow of air into the sealing device and the conduit;

d) inflating an inflation bag on the sealing apparatus by adjusting a control valve on the manifold to seal the end of the tube;

e) the control valve is adjusted to allow compressed air to enter the conduit, thereby pushing the shuttle until the shuttle exits the conduit carrying the pull cord.

26. The method of claim 25, further comprising the step of adjusting the control valve to deflate said inflatable bag to enable release of the sealing device from the conduit.

27. An apparatus for cleaning the inside of a pipe using a cleaning element such as a cylindrical block, said apparatus comprising a source of compressed air, a sealing device for sealing the inlet end of said pipe, and an inflatable air-filled bag for receiving air from said source of compressed air, said compressed air forcing the cylindrical block through the pipe after the cylindrical block is placed in the pipe and the inlet end is sealed with said sealing device.