A DEVICE AND METHOD FOR REMOVING IRREGULARITIES IN OR ENLARGING AN UNDERGROUND DUCT

Abstract: A device for removing irregularities in or enlarging a buried duct comprises a cylindrical housing corresponding approxi­ mately in diameter to the required diameter of the duct, an ex­ pandable shell comprising a plurality of tapered leaf members pivotally attached at their rear ends to the front of the housing, and remotely controllable drive means for moving the leaf members between contracted and expanded configurations. In operation, the apparatus is drawn through the duct with the leaf members in a contracted configuration in which they enter a portion of the duct of a diameter less than the required diam­ eter. The drive means is operated to force the leaf members outwardly against the sides of the duct to expand the duct. The leaf members are then retracted and the apparatus is drawn for­ ward. The apparatus is particularly intended for preparing damaged sewers prior to fitting an inner, lining pipe. By forming the shell in two sections, of which the nose is cylindrical in the contracted configuration and conical in the expanded configu­ ration, the apparatus can move forward a distance approxi­ mately equal to the length of the leaf members with each ex­ pansion and contraction cycle, a continuous tension being ap­ plied to the chain drawing the device forward.

Description: A DEVICE AND METHOD FOR REMOVING IRREGULAITIES IN OR ENLARGING AN UNDERGROUND DUCT This invention relates to a device for profiling an underground duct, for example an underground sewer which is to be repaired by fitting an inner pipe lining. In many of the developed industrial countries of the world, underground sewers have to a large extent reached an age at which they are in a state of severe disrepair and liable to collapse. One method of repairing sewers is to line the existing sewer pipe internally with plastics pipe sections or an expandable plastics sleeve. However, the condition of the original sewer is often such that the original earthenware pipe sections are displaced relative to each other or have already partly collasped. In these circumstances the diameter of an inner pipe lining made up of rigid plastics pipe sections is limited over the length of sewer being repaired to that determined by the worst irregularity in that length. The result is that the flow capacity of the repaired sewer may be considerably reduced. - Attempts have been made to hammer out the irregularities with a remotely controlled machine, but this has proved difficult to control and can worsen the state of collapse. It is an object of this invention to provide apparatus able largely to enlarge or correct the irregularities in an existing sewer in a relatively controllable and reliable manner. According to a first aspect of the invention, apparatus for travelling through an underground duct and for enlarging or removing irregularities in the duct comprises an expandable segmented shell including a series of shell parts arranged around a longitudinal axis of the apparatus and having respective outwardly facing surface portions for engaging the sides of the duct, wherein the shell parts are movable laterally with respect to the axis from a contracted configuration to an expanded configuration for forcing the sides of the duct away from the axis to enlarge a portion of the duct, and a nose portion extending in a longitudinal direction forwardly of the segmented shell portion and having an outer surface engaging the sides of the duct ahead of the said segmented shell portion. The nose portion may comprise a second expandable and segmented shell including a second series of shell parts arranged around a longitudinal axis and having respective second outwardly facing surface portions for engaging the sides of the duct, the shell part of the second series being movable transversely with respect to the said axis between a contracted configuration and an expanded configuration. The shell parts of both series preferably each have a front end and a rear end, the front ends of the shell parts of the second series are each coupled on a first diameter around a forward pivot assembly by a plurality of respective forward pivot joints, the rear ends of the shell parts of the second series are each coupled by respective intermediate pivot joints to the front ends of the shell parts of the first series, and the rear ends of the shell parts of the first series to a base member on a second diameter which is larger than the first diameter. In this case internally mounted fluid drive means are preferably coupled to the shell parts in the region of the intermediate joints, having a generally cylindrical outer surface when in the contracted configuration, thereby defining the penetration diameter, and a forwardly tapering outer surface in a fully expanded configuration. This tapering outer surface advantageously corresponds substantially in shape to the forwardly tapering outer surface of the first series of shell parts when in their contracted configuration, such that the portion of the duct expanded by the nose portion is shaped to receive the whole length of the first series of shell parts, whilst a trailing part of the apparatus, which may or may not include the pipe lining behind it, simultaneously moves into a substantially cylindrical duct portion created by the expansion of the first series of shell parts. According to a second aspect of the invention, there is provided apparatus for travelling through an underground duct and for enlarging or removing irregularities in the duct, wherein the apparatus comprises an expandable segmented shell including a plurality of shell parts arranged around a longitudinal axis of the apparatus and having respective outwardly facing surface portions for engaging the sides of the duct, and wherein the shell parts are drivable laterally with respect to the axis from a contracted configuration, in which at least a front end portion of the shell lies within a duct penetration diameter, to an expanded configuration in which the shell defines a forwardly tapered outer surface portion. Such tapering may be produced by a shell having two shell portions each having a respective series of transversely movable shell parts. Method aspects of the invention include a method of removing irregularities in or enlarging an underground duct comprising the steps of: (i) locating in the duct on expansion device including a leading expandable shell portion and a trailing expandable shell portion, which portions comprise respectively leading and trailing sets of shell parts which are movable laterally with respect to a longitudinal axis between a contracted configuration and an expanded configuration, the device being located in the duct with the shell parts in their contracted configuration and the leading shell portion in an unexpanded duct portion, (ii) driving the shell parts into their expanded configuration to force the sides of the duct away from the axis to create an enlarged duct portion having a front section which is forwardly tapering and a rear section having an overall diameter at least as large as the required diameter of the duct, (iii) causing the shell parts to return to their contracted configuration and the device to move forwardly by a distance such that leading shell portion enters a new unexpanded duct portion, and the trailing shell portion substantially occupies the said front section of the enlarged duct portion, and (iv) repeating steps (ii) and (iii) to traverse a required duct length. In a preferred method, the apparatus or the expansion device are subjected to a continuous forwardly directed force and the shell parts are reciprocated back and forth in a regular manner. In this way,the apparatus or device moves forward automatically on each contraction stroke. Providing a nose portion corresponding, at least in the contracted configuration, substantially to the penetration diameter largely prevents the inward collapse of the sides of the duct prior to moving forward the apparatus or device. The apparatus or device may be driven through the duct by repeatedly operating a hydraulic ram at an accessible location, the ram being alternately connected and disconnected during each operating stroke to a chain or wire connected to the device through the duct. The invention will now be described by way of example with reference to the drawings in whch:- Figure 1 is a perspective view of an embodiment of the present invention showing a device having a segmented front section comprising two sets of shell parts; Figure 2A is a cut away side view of the device of Figure 9 showing shell parts in a retracted configuration; Figure 2 B is a view similar to Figure 2 A out showing shell parts in an expanded position; Figure 3 shows an operative environment of the device shown in Figure 1- 2 in an underground duct; and Figure 4 shows an alternative expansion means for expanding the shell parts shown in Figures 1 - 3. Referring to Figures 1, 2A and 2B, a sewer pipe expansion device in accordance with t. e invention has a front part which is an expandable shell having two sets of shell parts in the form of leaf members, these comprising (i) a first trailing set of leaf members 130 attached at their rear ends to a cylindrical rear body member 110 by a set of circumferential rear pivot joints 142, and (ii) a second, leading set of leaf members 132 each pivotally attached at their rear ends to the respective front ends of the trailing leaf members 130 by intermediate pivot joints 133, and at their front ends to a rounded front end pivot assembly 134 carrying a number of circumferential front pivot joints 135. Mounted in the body portion 110 is a longitudinal hydraulic ram 112 which in this example is annular, with an annular piston 120, providing a central longitudinal bore. This bore allows a central passage, defined by a tube 123, to be provided over the whole length of the device to receive a chain 122. The piston 120 carries a pivot block 115 which is, in turn, coupled by a plurality of radiating connecting links 116 to the intermediate pivot joints 133 for converting longitudinal motion of the piston 120 into lateral (with respect to the longitudinal axis of the device) motion of the front ends of the trailing leaf members 130 and the rear ends of the leading leaf members 132. The two sets of leaf members thus form an expandable shell having a leading portion constituting a nose portion for penetrating and expanding an unenlarged duct portion, and a trailing portion for subsequently further expanding that duct portion to an overall diameter such that the body portion can then move forwardly into the duct portion without further expansion of the duct sides. In Figure 1, the device is shown in its expanded configuration with the trailing set of leaf members 130 forming an approximately cylindrical envelope having a diameter at least as large as the diameter of the body member 110. The leading set of leaf members 132 form a generally conical surface which tapers forwardly from a diameter at least as large as that of the body member 110 to a smaller penetration diameter at the extreme forward end of the device. In the contracted configuration, the trailing leaf members 130 form a similar forwardly tapering conical surface whilst the leading leaf members 132 form a cylinder of the smaller penetration diameter. The fully contracted and expanded configurations are shown more clearly in Figures 2A and 2B respectively., which are sectional views. The split front part of the device shown in Figures 1 - 3 has particular advantage in the enlargement of a duct. As illustrated in Figure 3 where the device is shown in side elevation, the leading leaf members 132 in their contracted configuration are able to penetrate an original duct 140 of diameter D2 which is larger than the penetration diameter referred to above but smaller than thediameter of the body member 110. The device is being used to enlarge the original duct 140 to a required diameter D2 corresponding to the diameter of the body member 110, and at the same time, for drawing a pipe lining 144 of similar diameter through the duct behind it. With a continuous tension applied to the chain 122 (attached to the rear end of the lining 144 to place the joints between the sections of the lining under compression), the ram 112 (Figures 2A and 2 B) is operated to expand the leaf members into the position shown by the dotted lines 142, forcing out the sides of the duct to the new diameter D2 . Since the leaf members are all of approximately equal length the forwardly tapered profile of the expanded duct formed by the expansion of the leading leaf members 132 corresponds to the forwardly tapered surface formed by the trailing leaf members 130 in their contracted configuration. Thus, when the ram 112 is caused to retract, the whole device and the pipe lining 144 can move forward by a distance "S" which is the length of the leaf members. This means that in a duct enlarging operation a full length "S" of the duct can be enlarged with each cycle of the ram 112. formed by the leading leaf members 132 reduces the possibility of the duct sides collapsing ahead of the device during the expansion operation, because the front ends of the leaf members 132 merely engage the duct sides to stablise them without expanding them at that point. Another embodiment of the invention is shown in section in Figure 4. In this embodiment a split expandable shell is employed as in Figures ls 2A and 2B, but in this case a wedge expander 146 is coupled to the piston 120 instead of pivotable connecting links to expand the leaf members 130 and 132. This construction can be preferable when space is limited as in a device designed for relatively small ducts, typically 150mm diameter or less.

Claims: CLAIMS: 1. Apparatus for travelling through an underground duct and for enlarging, or removing irregularities, in the duct, wherein the apparatus comprises an expandable segmented shell portion including a series of shell parts arranged around a longitudinal axis of the apparatus and having respective outwardly facing surface portions for engaging the sides of the duct, wherein the shell parts are movable laterally with respect to the axis from a contracted configuration to an expanded configuration for forcing the sides of the duct away from the axis to enlarge a portion of the duct, and a nose portion extending in a longitudinal direction forwardly of the segmented shell portion and having an outer surface for engaging the sides of the duct ahead of the said segmented shell portion. 2. Apparatus according the claim 1, wherein the nose portion comprises a second expandable and segmented shell including a second series of shell parts arranged around a longitudinal axis and having respective second outwardly facing surface portions for engaging the sides of the duct, the shell parts of the second series being movable transversely with respect the said axis between a contracted configuration and an expanded configuration. 3. Apparatus according to claim 2, wherein the shell parts of the first series and the second series each have a front end and a rear end, the front ends of the shell parts of the second series are each coupled on a first diameter around a forward pivot assembly by a plurality of respective forward pivot joints, the rear ends of the shell parts of the second series are each coupled by respective intermediate pivot joints to the front ends of the shell parts of the first series, and the rear ends of the shell parts of the first series are each coupled to a base member on a second diameter which is larger than the first diameter. 4. Apparatus according to claim 3, including internal fluid pressure drive means coupled to the shell parts in the region of the intermediate joints. 5. Apparatus according to claim 1, wherein the nose portion defines a generally cylindrical outer surface defining a penetration diameter in at least one configuration of the shell parts. 6. Apparatus according to claim 2, wherein the -shell parts of the nose portion define a forwardly tapering outer surface in their fully expanded configuration. 7. Apparatus for travelling through an underground duct and for enlarging, or removing irregularities in the duct, wherein the apparatus comprises an expandable segmented shell including plurality of shell parts arranged around a longitudinal axis of the apparatus and having respective outwardly facing surface portions for engaging the sides of the duct, and wherein the shell parts are drivable laterally with respect to the axis from a contracted configuration, in which at least a front end portion of the shell lies within a duct penetration diameter, to an expanded configuration in which the shell defines a forwardly tapered outer surface portion. 8. Apparatus according to claim 7, wherein the shell defines, in the expanded configuration, an outer surface having a forwardly tapered front surface portion and a cylindrical or rearwardly tapered rear surface portion. 9. Apparatus according to claim 8 having, in the contracted configuration of the shell parts, a forwardly tapered rear outer surface portion corresponding substantially in shape to the said forwardly tapered outer surface portion of the shell in the expanded configuration of the shell parts. 10. A method of removing irregularities in or enlarging an underground duct comprising:- (i) locating in the duct an expansion device including a leading expandable shell portion and a trailing expandable shell portion, which portions comprise respectively leading and trailing sets of shell parts which are movable laterally with respect to a longitudinal axis between a contracted configuration and an expanded configuration, the device being located in the duct with the shell parts in their contracted configuration and the leading shell portion in an unexpanded duct portion; ; (ii) driving the shell parts into their expanded configuration to force the sides of the duct away from the axis to create an enlarged duct portion having a front section which is forwardly tapering and a rear section having an overall diameter at least as large as the required diameter of the duct; (iii) causing the shell parts to return to their contracted configuration and the device to move forwardly by a distance such that leading shell portion enters a new unexpanded duct portion, and the trailing shell portion substantially occupies the said front section of the enlarged duct portion; and (iv) repeating steps (11) and (iii) to traverse a required duct length. 11. A method according to claim 10, wherein a continuous forwardly directed force is applied to the device over a plurality of cycles of steps (ii) and (iii). 12. A method of lining an underground duct, including enlarging the duct as defined in claim 10, and simutaneously feeding a lining pipe into the duct. 13. A device for removing irregularities in or enlarging an underground duct comprising an expandable segmented shell having two sets of shell parts arranged around a longitudinal axis of the device, the two sets comprising a front set in which the shell parts are each pivotally attched by front end portions thereof to a forward pivot assembly, and a rear set in which the shell parts are each pivotally attached by front end portions thereof to rear end portions of respective shell parts of the front set, and by rear end portions thereof to a base member. 14. A method of removing irregularities in or enlarging an underground duct including: (i) locating in the duct apparatus according to any of claims 1 to 9 with the shell parts in their contracted configuration; (ii) driving the shell parts in to their expanded configuration to create an expanded duct portion; (iii) returning the shell parts to their contracted configuration and causing the apparatus to move forwardly into the expanded duct portion; and (iv) repeating steps (ii) and (iii) to traverse a required length of the duct. 15. A method according to claim 14, wherein the expanded duct portion is forwardly tapered over at least a part of its length.

Inventors: YARNELL, IAN ROLAND
Applicants: I.P.D. SYSTEMS LIMITED
Application year: 1984
Main classification: E03F3
IPC codes: E21B7, F16L55, E03F3