Conduit space recovery system

Abstract

Space in a conduit having at least one cable therein which is surrounded by a duct is recovered by longitudinally cutting the duct and removing the duct from around the cable. The duct may be pulled out of the conduit and past a blade to affect the cutting, or a blade may be pulled through the conduit to cut the duct while still in the conduit.

Claims

1. A method of recovering space in an underground conduit having at least one active cable positioned in a duct which is in the conduit, the method comprising the steps of providing an apparatus for pulling the duct partially out of the conduit while the conduit is positioned underground, cutting the duct that has been pulled out of the conduit without damaging the active cable, and removing the cut duct from around the active cable such that when all of the duct has been cut and removed from around the active cable, space is recovered in the conduit.

2. The method of claim 1 wherein the step of pulling includes the step of grasping the duct with opposed wheels, and rotating the wheels to pull the duct out of the conduit.

3. The method of claim 1 wherein the step of pulling includes the step of engaging the duct with opposed tractor drives.

4. The method of claim 1 further comprising the step of guiding the duct as the duct is being pulled out of the conduit.

5. The method of claim 1 further comprising the step of protecting the cable while cutting the duct.

6. The method of claim 1 further comprising the step of inserting an innerduct in the recovered space.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1A is a schematic and end view of a conduit which is filled with three innerducts, each of which is housing a communications cable.

(2) FIG. 1B is a schematic view, like FIG. 1, showing that the innerducts have been slit lengthwise.

(3) FIG. 1C is a schematic view, like FIGS. 1 and 2, showing the space in the conduit that is recovered after the split innerducts have been removed.

(4) FIG. 2 is a somewhat schematic, fragmented, sectional view of a typical manhole with a cable extending therethrough.

(5) FIG. 3 is a sectional view taken substantially along line 3-3 of FIG. 2 and showing an end wall of the manhole.

(6) FIG. 4 is a schematic view like FIG. 2 showing a portion of an innerduct having been removed from the conduit.

(7) FIG. 5 is a schematic top representation of a device positioned in the manhole which cuts and removes the innerduct from the conduit according to one aspect of the present invention.

(8) FIG. 6 is a schematic representation similar to FIG. 5 showing some alternative features of the present invention.

(9) FIG. 7 is a somewhat schematic depiction of an alternate system to cut and remove innerduct from the conduit.

(10) FIG. 8 is an end view of the device of FIG. 7.

PREFERRED EMBODIMENTS FOR CARRYING OUT THE INVENTION

(11) A conduit 10 for carrying communications cables 12 typically will extend longitudinally in the ground for up to thousands of feet. As previously described, when multiple cables are to be positioned in a conduit, it is easier to insert them and to keep them from damaging existing cable or being twisted with existing cable by inserting them into some kind of duct, commonly known as an innerduct, such as the plastic tubing innerduct 11 shown. However, as shown in FIG. 1A, these innerducts 11 take up space that could otherwise be used for additional cables 12.

(12) In accordance with the present invention, as shown in FIG. 1B, one or more of the innerducts 11 may be cut along their length, as at 13, at multiple locations. Then the pieces of innerduct 11 may be removed from around the cables 12 which creates a recovered space 14 in the conduit 10 as shown in FIG. 1C. Then it would be preferable to encase the freed cable or cables 12 in a fabric sleeve so that additional cables could be inserted into conduit 10 without encountering the friction caused by an exposed cable and without potentially damaging existing cable. In addition, a fabric innerduct M, such as that shown in U.S. Pat. No. 6,251,201, and sold under the trademark MAXCELL® by Wesco Distribution, Inc. of Pittsburgh, Pa., could be inserted into space 14 and new cables could be inserted of inside the compartments of the fabric innerduct.

(13) FIG. 2 schematically depicts a conventional cable service point such as a manhole generally indicated by the numeral 15. Manhole 15, of course, has a normally covered open top 16, a bottom surface 17 on which workers may stand, and sidewalls 18. When conduits are initially inserted in the ground 19, manholes 15 are provided every several hundred feet for access to the cables 12 (one shown in FIG. 2 for convenience) which extend across the manhole 15 from one sidewall 18 to the other sidewall 18. The cable 12 shown in FIG. 2 is fragmented to indicate that the cable 12 does not pass through the manhole 15 from one sidewall 18 to the other. Rather, typically, a coil of cable 12 may be found in a manhole 15. As shown in FIG. 3, the conduit 10 and innerducts 11 (one shown in FIG. 3 for convenience) are exposed in manhole sidewalls 18.

(14) The operation of the system of the present invention can take place in a manhole 15, and in accordance with an embodiment of the present invention, the innerduct 11 to be operated upon can be pulled a short distance into the manhole as shown in FIG. 4. Then an assembly, generally shown in FIG. 5, can be used to remove and cut innerduct 11 as now will be described.

(15) Assembly 20 is shown as having a frame generally indicated by the numeral 21. Frame 21 includes spaced support arms 22 the edges of which rest against manhole sidewall 18. Arms 22 are spaced from each other with cable 12 being positioned therebetween. Each arm 22 carries a drive device generally indicated by the numeral 23. Drive 23 can be as shown in the form of rotating wheels 24 or could be in the form of a conventional tractor drive. In the form shown, wheels 24 first clamp down on opposite sides of the exposed innerduct 11, as is shown in FIG. 5, and then wheels 24 may be rotated in opposite directions, as shown by the arrows in FIG. 5, to pull innerduct 11 out of the conduit 10 and move it to the left in FIG. 5. Wheels 24 may be hydraulically driven and may be provided with a knurled surface to assist in the engaging and pulling functions. Since frame 21 is braced against manhole sidewall 18, the force used in the pulling process is borne by sidewall 18.

(16) Each arm 22 of frame 21 also includes a cutting device generally indicated by the numeral 25. In the embodiment shown in FIG. 5, cutting device 25 is schematically shown to be in the form of a stationary blade 26. Opposed blades 26 extend inwardly from each arm 22 a sufficient extent so as to come into contact with innerduct 11 but not so far as to touch and potentially damage active cable 12. Thus, as drive 23 moves innerduct 11 past cutting device 25, innerduct 11 is longitudinally severed at two circumferentially spaced locations and the cut pieces 27 of innerduct 11 may be removed from around cable. If desired to cut innerduct 11 in three or more locations, additional cutting devices 25 can be provided. Pieces 27 may then be ground up and environmentally recycled.

(17) FIG. 6 depicts some alternative features to the embodiment of FIG. 5 just discussed. Thus, as shown in FIG. 6, the drive device 23 is shown in the form of conventional tractor devices 28 and the cutting device 25 is shown in the form of rotating cutter wheels 29. Cutter wheels 29 can rotate in a clockwise direction against the direction of movement of the innerduct 11 or, if desired, could rotate in a counterclockwise direction to actually assist tractor devices 28 in the movement of innerduct 11.

(18) FIG. 6 also shows that if desired, a split metal tube 30 can be inserted into the conduit 10 and around innerduct 11 if guidance of the innerduct 11 is required as it is being removed from the conduit 11. Tube 30 extends out of the conduit and into manhole 15 and is shown as having a slot 31 at the location of drive devices 23 so that they may engage the innerduct 11 and other slot 32 at the location of cutting devices 25 to that they may longitudinally sever the innerduct 11. Moreover, if necessary to protect the live cable 12 from damage which might be occasioned by accidental contact with the cutting devices 25, a split metal tube 33 may be inserted a short distance into conduit 10 around cable 12. Tube 33 extends into manhole 15 to 50 protect cable 12, if necessary.

(19) FIGS. 7 and 8 show an alternative system to accomplish space recovery in a conduit. There, a cutting assembly, generally indicated by the numeral 40, includes a body portion generally indicated by the numeral 41. Body portion 41 must extend around the cable 12, but because live cables cannot be severed, body portion 41 is split into two sections 41A and 41B. Body portion 41 is installed around a cable 12 at a service point, such as the manhole previously described, where the cable 12 is exposed. The innerduct having an edge 42 may then be pulled into the manhole and the two halves can then be positioned around the cable 12 and can be connected by any suitable means. For example, each half 41A, 41B may be provided with a small apertured flange 43 which mate with each other and receive a fastener.

(20) Cutting assembly 40 includes a plurality of outer guides 44 which are positioned on the circumferential outside of the innerduct 11 being worked on. A blade 45 extends from each guide 44 to body portion 41. Blades may be attached to guide 44 and/or body portion 41 in such a manner that they could be readily changed, if necessary. While three blades 45 are shown, which will longitudinally slit innerduct 11 into three pieces, as is evident from the previous discussion of FIGS. 5 and 6, at least two blades 45 are required. Moreover, more than three blades 45 could be utilized if desired. At the outset of the cutting process, blades 45 are positioned adjacent to end 42 of innerduct 11.

(21) Blades 45 longitudinally slit innerduct 11 by causing relative movement between cutting assembly 40 and innerduct 11. This can happen by causing cutting assembly 40 to remain stationary and pulling innerduct 11 past blades 45 (to the left in FIG. 2) in a similar manner as described with respect to FIGS. 5 and 6. Or cutting assembly 40 can be caused to move through the conduit 10. Such can be accomplished by blowing one or more pull tapes into the conduit 10 in a conventional manner. Then the tape(s) can be attached to the cutting assembly 40. To that end, body sections 41A and 41B may be provided with slots 46 so that the pull tape can be connected thereto. Then by pulling on the tape, downstream from the end 42 of innerduct (at the next adjacent manhole), cutting assembly 40 can move, to the right in FIG. 2, through conduit 10 to cut innerduct 11. Slots 47 are also provided at the other end of cutting assembly 40 so that a tape can be attached thereto to pull cutting assembly 40 in the reverse direction, if necessary.

(22) When the innerduct 11 has been longitudinally split as shown in FIG. 1B, its pieces may be easily pulled out of conduit 10. If additional innerducts 11 are in conduit 10 and if it is desired or necessary to remove them all, the process may be repeated until all innerducts are spliced and removed creating the recovered space 14. As previously described, the pieces of the innerduct may be ground up and environmentally recycled. Once the space of one or more removed ducts has been recovered, the fabric innerduct M such as that shown in U.S. Pat. No. 6,251,201 could be inserted into that space so that one or more new cables could be inserted into the fabric innerduct.

(23) In view of the foregoing, it should be evident that a conduit space recovery system as described herein accomplishes the objects of the present invention and otherwise substantially improves the art.