The present invention relates to an apparatus for pushing pipes along a duct, said apparatus being arranged to be positioned in association with the duct, and including a pushing piston which is arranged to exert a forward pushing force on a pipe with support of a holding-up device, and a tube supporting device for carrying the pipe around the pushing piston during movement of the later.

The invention also relates to a method for pushing forward a pipe along a duct, comprising feeding the pipes to the duct and successively pushing forward them by means of a pushing piston.

Primarily, the invention is intended to be used for jointing and pushing forward the jointed pipes for so called "relining".

"Relining" is a method by means of which pipes are jointed and pushed, e.g. from a manhole, into an existing pipe line connected to the manhole, for reconditioning the pipe line.

Devices of the kind defined by way of introduction are earlier known. These and other devices intended for relining each have at least sme of a number of disadvantages. Of these disadvantages the following may be mentioned:

1. A dimensioning of the apparatus that makes impossible bringing down and using the same in a simple way in a manhole. Thus, extra space for the apparatus may be required outside the manhole, in line with the pipe line intended to be reconditioned, e.g. for making space for the pushing piston. In some cases it is not at all possible to perform the operations necessary without introductory excavating works in connection with a manhole or along the pipe line.

2. A complex and expensive associated equipment.

3. Requirement for a large working staff, i.e. normally more than two persons.

4. The operations and working steps for relining a certain pipe line is time consuming.

A general object of the invention is to provide an apparatus and a method greatly simplifying reconditioning of an existing duct by lining the same with pipes.

A more specific object of the invention is to provide an apparatus and a method for pushing pipes along a pipe line, for relining the same as discussed above, which, as compared with earlier apparatus and methods is simpler and cheaper as to its design, admits lowering into and use in a simple way in a manhole, within the space admitted by the manhole, and admits relining of a certain pipe line for a considerably cheaper price and in a considerably shorter time than has been possible thus far.

These and other objects are attained in that, in the apparatus according to the invention, the holding-up device comprises an elongated support, means are arranged for supporting the pushing piston on said elongated support so as to be movable between an operative position in which the piston is ready for pushing a pipe in the direction of the duct, and a pipe receiving position deviating from said operative position, and means are arranged for carrying at the leading end of said elongated support a pipe retaining device for holding the trailing end portion of a previously pushed forward pipe, while performing a connecting stroke with the piston for connecting a pipe, carried around the piston, with said previously pushed forward pipe.

The method according to the invention is characterized by exerting the action of the piston on each pipe after it having been positioned around the pressure piston when the later takes a position deviating from the pushing direction thereof, and

performing, before the pushing forward operation proper, a connect¬ ing stroke by the piston for connecting the pipe carried around the piston with the trailing end portion of a previously pushed forward pipe.

Different advantageous embodiments of the invention have obtained the features defined in the respective sub-claims.

As an example of the importance of the invention in practice may be mentioned that, in one embodiment of the apparatus according to the invention, intended for relining pipe lines as discussed above, relining of a pipe section of 50 - 100 meters could be carried through in appr. one hour by a staff of two persons.

The invention will now be described more closely with reference to an embodiment of the apparatus of the invention shown on the attached drawings, wherein

Figure 1 shows a perspective view of the apparatus, Figure 2 is a perspective view of a so called short pipe with a collar attached to the end thereof,

Figure 3 illustrates a further perspective view of the apparatus, one portion thereof, however, taking another position than in Figure 1,

Figures 4-8 in section through the bottom portion of a manhole and a short section of a connected older pipe line illustrate a number of consecutive steps at use of the apparatus according to the invention, Figures 6 and 8 showing the apparatus partly sectioned.

With reference particularly to Figures 1 and 3 the apparatus as main portions includes an elongated trough-shaped bottom portion or cradle 2, open at both ends, a piston-cylinder device generally designated 4, and a collar-retaining device generally designated 6, whereof the two last-mentioned devices will be described more closely below. Since the present description will be carried through partly with reference to pipes of the short pipe type, with which the apparatus will be working, such a pipe will be briefly

described with reference to Figure 2.

The pipe, conventionally manufactured of hard plastic, and being designated 8, at each end has a number of outer grooves 10 intended to cooperate, in a manner not shown and described, with an end collar 12. Briefly, one or more of the grooves 10 can contain sealing rings for sealing between the tube 8 and the collar 12, and otherwise de ine protrusions for cooperation with corresponding formations in the inside of the collar 12, for snap connection between the pipe 10 and the collar 12. The collar 12 has a syπmetrical shape for receiving one pipe 8 in each end. Short pipes and collars of the kind described here can be of conventional type, available on the market.

The cylinder, designated 14, of the piston-cylinder device 4 is pivotally mounted at 16 on a cross piece 18 between the sides of the cradle 2, at one end thereof. The piston rod included in the piston-cylinder device is designated 20, and is shown with dashed and dotted lines in Figure 1. As will appear from the following description, the cradle 2 and the cross piece 18 may be said to form part of a "holding-up device" supportingly cooperating with the piston 20 during operation thereof. The piston rod 20 at its leading end carries a plate 22 with a partly essentially circular contour 24 with a radius somewhat less than the inner diameter of the tube 8 with the attached collar 12. The plate 22 also has a straight bevel , 26 with a function to be descibed more closely below. The ratio between the radii of curvature of the plate 22 and the trough 2 is such that the pipe 8 can be supported with clearance between the contour 24 and the inner wall of the trough 2, said inner wall in the position shown in Figure 1 extending essentially coaxial with the contour 24.

By means of three struts, or bars, 27 the plate 22 is connected to a pressure abutment plate 28, which is located essentially in plane with the rear end of the piston rod. The plate 28 has a radius, which is greater than the inner radius of the collar 12 but less

than the inner radius of the trough 2. The plate 28 has a recess 30 for the cylinder 14 and the appurtenant structure extending along the same, so that the plate 28 can move freely along the cylinder 14 between the entirely rear position shown in Figure 1 and a forward position in the vicinity of the leading end of the cylinder, corresponding to the position of the plate 22 shown with dashed and dotted lines in Figure 1.

The hydraulic fluid supply to the cylinder 14 takes place through hoses 32 and 34, respectively, and a hydraulic fluid branch pipe 36 extends to the leading end of the cylinder 14. The details of the design of the piston-cylinder device 4 can, as mentioned above, be of a conventional kind and need therefore not be described more closely here. The hoses 32 and 34 are connected to a valve box 38 which can be attached to the trough 2 or, alternatively, to the collar retaining device 6 described more closely below. Hydraulic hoses 40 lead to the valve box 38 from a pump assembly, not shown, the hoses 40 being so long that the pump assembly can stand on the ground adjacent to a manhole in the bottom of which the apparatus is arranged in a way appearing more closely from Figures 4-8 and the corresponding description below. With a control rod 42 connected to the valve box 38 the valve is controlled to direct hydraulic fluid as desired in the respective hoses 32 and 34. The pump assembly can be of a kind known per se and available on the market, e.g. a portable 220 V so called hydraulic packet. The apparatus according to the invention and such a pump assembly do not occupy greater space than being able to be carried together in a small delivery van or a great passenger car.

The collar retaining device 6 includes a plate 44 which, by means of an arm 46 on each side of the trough 2, is pivotally supported in the end faces of the cross piece 18 through the corresponding wall portions of the trough 2. A handle 45 is attached to the plate 44 to allow lifting of the later as will be described more closely below. In the position shown in Figure 1, in which the plate 22 is completely inserted, the plate 44 is located on a distance from the

plate 28 which, for reasons appearing from the description below with reference to Figures 4-8, essentially corresponds to the added lengths of a pipe 8 with attached collar 12 according to Figure 2, and a further collar 12 located at seme distance from that end of the pipe 8 not provided with a collar. The plate 44 furthermore has an inner arcuate recess 48 with a radius essentially corresponding to the outer radius of the pipe 8, and thus is smaller than the outer radius of the collar 12.

The way of operation of the described apparatus in connection with relining shall now be described closer with reference to Figures 3- 8.

The apparatus is placed in the way shown in Figures 4-8 in the bottcsti of a manhole 50, from which the pipe line to be reconditioned by relining starts. The beginning of this pipe line is shown at 52.

More particularly, the apparatus is placed in line with the pipe line 52 and so that the rear end of the trough 2 is supported against a step 54 in the bottom of the manhole. This step 54 can be formed in a conventional way as the end of an elongated recess in the bottom of the manhole, leading to an opening to which the pipe line 52 is connected. Lacking such a premanufactured recess some form of stop piece, forming a step, can be placed between the wall of the manhole and the rear end of the trough 2. Suitably, the step shall not be higher than allowing the swinging movement of the piston-cylinder device 4 to the position shown in Figure 3, i.e. so that the rear end of the cylinder structure escapes the step without necessitating lifting of the trough to allow it. However, the apparatus according to the invention is not heavier than well admitting such lifting of the rear end of the trough 2, e.g. up onto the step, where appropriate.

With the apparatus arranged in the way described, the piston- cylinder device is swung to the position shown in Figure 3 so that it points -upwardly and admits receipt of a pipe, e.g. of the kind

shown in Figure 2 with a collar 12 attached thereto. More particularly, the pipe is moved, with the collar 12 first, over the support structure formed by the plate 26 and the rods 27, so that the collar will abut against the plate 28. The piston-cylinder device with the pipe sitting thereon is thereafter lowered to the position shown in Figures 4 and 6-8 and a pushing forward stroke of the pushing piston 20 is started by operating the stick 42. This stroke is ended by the leading edge of the collar 12 being stopped by the stop abutment 44, as shown in Figure 4.

The piston-cylinder device 4 is now raised again for receiving a new pipe 8 with a collar 12 attached thereto, as is indicated by the arrow designated 58 in Figure 5. The piston-cylinder device 4 with the pipe sitting thereon is thereafter lowered again, as indicated by the arrow 60 in Figure 5. Due to the above described dimensioning of the distance between the plates 28 and 44, the leading edge of the pipe 8 is then placed with some clearance with respect to the collar 12 of the pipe already pushed forward. A joining stroke of the pushing piston 20 is now started in order to snap the leading edge of the new pipe into the collar. Figure 6 illustrates the end of this step.

The collar stop abutment 44 is now swung upwardly by means of the handle 45 as indicated by the arrow 62 in Figure 7, so that it will not form an obstacle to the collar 12 sitting on the first pipe 8 during the continuing pushing forward of the pipes now joined. However, as soon as this collar has passed the raised stop abutment 44, the later is lowered again for forming a stop to the collar of a following pipe. Figure 8 illustrates this pushing forward step, indicated by arrow 64, during the ending phase thereof, iπitediately before the collar of the pipe sitting on the support device 22, 27 is going to be stopped by the collar stop abutment 44.

The cycle illustrated by Figures 4-8 is thereafter repeated a required number of times until a new pipe line, consisting of the pipes 8 joined together by means of the collars 12, has been pushed

forward along the whole length of the old pipe line, e.g. to the next manhole.

For performing the described work two persons are enough. One person is down at the bottom of the manhole standing astraddle over the apparatus, this person receiving pipes handed down from the other person who is on the ground level. The person in the manhole thereafter carries through the steps illustrated in Figures 4-8 for each pipe. Switching on and off the pump assembly located on ground level and connected via the lines 40 is dealt with by the person located there, of course.

Of course, the invention is not limited to the embodiment described above and shown on the drawings, but can be modified within the scope of the claims.

Thus, it would be well possible to remotely control the apparatus according to the invention entirely from ground level by carrying through the swinging movements of the piston-cylinder device 4 and the stop abutment 44 by means of small hydralic cylinders controlled from ground level. Of course, the control device 38-42 will then likewise be located on ground level. A suitable guide means for bringing down each pipe onto the uppwardly pointing piston-cylinder device will then also be arranged.

Furthermore a retaining device 44 is described above and shown, which is particularly suited for outer collars. At pipe lines with inner collars a clamping device for the tube including the collar can instead be used. This clamping device can e.g. be designed with jaws or similar which are abutted against the outside of the trailing end portion of the pipe. The jaws can be hydraulically operated.

It will be appreciated from the description above and the embodiment shown on the drawings that the invention makes possible use of an apparatus for relining without requiring any extra operations, such

as excavating works in connection with the manhole or along the pipe line. Above all this is obtained by the illustrated design where a pipe pushed forward by the apparatus during the pushing forward movement surrounds the pushing piston, which minimizes the length of the apparatus.