The present invention relates to a treatment element for treating the inside of a pipe, wherein during treatment a medium flow, in particular a compressible medium such as air is maintained in said pipe, while the treatment element is moved in the lengthwise direction through the pipe under the influence of the thrust of the medium against said element and of a flexible pulling element controlling the movement of said treatment element. The invention also relates to a method for treating the inside of a pipe.

Known treatment elements are relatively inflexible and because of that they are mainly used for treating substantially straight pipes with little change of the cross section.

The object of the present invention is to provide a treatment element that is improved regarding the known treatment element.

To this end, the treatment element is characterised in that the treatment element comprises a bag which is flexible for radial compression, with the edge of the open end being connected to a flexible pulling element and at said opening and along the longest part of its length from that opening radially free compressible, which bag has along a part of its length a wall part running in the peripheral direction, which part is pressed against the wall of the pipe during treatment of the pipe by the thrust of the medium against the treatment element, and whereby the inner wall of the pipe is treated, as well as a method for treating the inside of pipes.

If this treatment element is held in the medium flow, it vill bulge out due to the thrust produced. Thereby the bag is pressed against the inner wall of the pipe and can e.g. clean this by sanding. The treatment element can be controlled or slowed down by means of the flexible pulling element in such a way that it moves with the medium flow in the pipe, or moves in the opposite direction to it, or stands still.

The treatment element according to the present invention is advantageous in that its bag can easily be inserted in the pipe through a small aperture, because this bag is radially free compressible. This is very advantageous at e.g. pipes of an air conditioning system for buildings. Such systems are often not provided with provisions for the insertion of a treatment element into the pipe, while there is often little space to make an acess opening in the pipe. Furthermore the bag of the treatment element can easily adapt to cross- sectional changes of the pipe. Cross-sectional changes are for example at connecting flanges of pipe parts projecting into the pipe, and they also occur often at guide vanes present in curves of air conditioning pipes. Sharp curves of more than 90o also give no rise to problems for the treatment element according to the present invention. The treatment element according to the invention is likely not to stick in the pipe.

Thus the invention provides a treatment element of simple design, which is relatively small and light and hardly sensitive to disturbances. Besides such treatment element can be fabricated cheap from for example a funnel shaped bag of woven cloth, connected to a rope.

The treatment element according to the invention is pre¬ eminently suitable for treating relatively fragile or very small pipes, which are especially used at the more or less over pressureless transport of gaseous media, such as air. Such pipes are often also supported by a relatively weak structure. Because of that, for treating such pipes no use can be made of known treatment elements which move by an own drive with for example wheels.

Treatment elements that are moved through the pipe with the aid of a medium flow are a.o. known from US-2,508,659 and 2,481,152 and from DE-U-8506314.2.

The treatment element according to US-2,508,659 comprises a bag of which the edge of the open end is connected to flexible pulling elements, while that same edge is connected to resilient rods, which try to keep the open end of the bag in the opened position. A rigid rod extends through the bag, along which the flexible pulling element is

led at the front end of the bag, while at the back end of the bag the resilient rods are connected to that rod. When a pulling force is exerted on the flexible pulling elements, the bag will be closed against the action of the resilient rods. US-2,481,152 comprises a bag as well, which along its length is provided with spaced strengthening rings, which keep the bag in the opened position. The front strengthening ring at the open end of the bag is connected to the flexible pulling element. The part of the open end of the bag that extends beyond that front strengthening ring and that grates along the inner wall of the pipe, is connected to the flexible pulling element as well. By this that edge of the bag is prevented from being folded over by the flow, as a result of which the abrasive action is lost. Finally DE-U- 8506314.2 describes a rigid hollow conical treatment element of for example plastics, the walls of which have a relatively high flexural rigidity, and which press resiliently against the inner wall of the pipe to be cleaned.

The bag of the treatment element known from US-2,508,659 and 2,481,152 is not radially free compressible. Such treatment element lacks the advantageous of the treatment element according to the present invention, The treatment element according to US-2,508,659 is not able to pass curves in the pipe. US-2,508,659 and 2,481,152 don't show, that the treatment element as discussed in there is suitable for treating the insic of a pipe wherein a compressible medium such as air flows t÷nrough the pipe. The treatment element according to DE-U-8506314.2 lacks the bag, and is also not suited to be controlled with the aid of a flexible pulling element.

Contrary to treatment elements known from the three publications mentioned above it is surprisingly found out that the treatment element according to the present invention, comprising a radially free compressible bag connected to a flexible pulling element, bulges out in the i -jdium flow without the need for the bag to be provided with means to keep the bag in the opened position. It seems that the medium thrust is sufficiently capable that the wall part of the treatment element is pressed against the wall of the

pipe, with or without a pulling force exerted on the flexible pulling element.

The flexible bag of the treatment element can for example be made of woven cloth. For, for example, cleaning of the inside of the pipe it is preferable for the treating outside surface of the treatment element to be covered with an abrasive.

It is preferable that the bag of the treatment element, in the part situated past the treating outside surface, should merge into a part of reducing cross-section, ending in an aperture for allowing through the medium. In this way the treatment element will be flowed through by the medium, while the medium thrust is caused through the inlet aperture of the treatment element being greater than the outlet aperture. In order to be able to vary the ratio between the inflow aperture and the outflow aperture of the treatment element depending on the conditions, it is preferable for the treatment element to be provided in the vicinity of the outflow aperture with means for varying the cross-section of said aperture.

It is also possible to cause a thrust of medium in an alternative manner. This is preferably achieved by fitting a flow element inside the bag of the treatment element.

As a further improvement of treating the inside of a pipe, preferrably a pipe of an air conditioning system in a building, the invention provides a useful method. The problem of conveyance and collecting of dirt that has come away during treatment is solved herewith.

According to this method, in the pipe a flow of a compressible medium is generated and maintained, and while a compressibel medium is flowing through the pipe, a treatment element is moved in the lengthwise direction through the pipe under the influence of the thrust of the medium against said element and of a flexible pulling element controlling the movement of said treatment element, while the thrust of the medium against said element presses a flexible wall part of the element running in the peripheral direction against the wall of the pipe, wherein the direction of flow of the medium during the treatment is opposite to the usual direction of

flow .

Because a medium is flowing through the pipe, dirt or other material that has come away during treatment is automatically conveyed to the downstream end of the pipe. At for example air conditioning systems of buildings this down stream end is positioned centrally, wherefrom during normal operation of the system the conditioned air branches to the different living rooms over the building. Directing the flow in the opposite direction during the carrying out of the method ensures that the material which has come away during the treatment does not flow into the living rooms. Centrally collecting material that has come away during treatment facilitates its removal.

It is preferable if the pipe forms part of an air conditioning system for buildings that an end of the pipe is already or is now connected to the suction side of an air conditioning cabinet or of a mobile fan unit. If the pipe in normal circumstances is already being used for the suction of air out of the living rooms, this is automatically the case. If this is not the case, there is still a possibility of using the air conditioning cabinet already present, in which case then the flow of the medium during the treatment must be directed in the opposite direction to the usual direction of flow. It can also be an advantage while the process is being carried out to have the air treatment cabinet to which the pi' o be treated is connected blown out in an essentially closed space in which the air conditioning cabinet is situated. In that case the material c.rried along with the medium Tlow is collected in said space. After the completion of the treatment, this generally fairly readily accessible space can be cleaned.

Controlling of the movement of the treatment element in the pipe by means of a flexible pulling element can be carried out by fixing a bracket with a flexible guide means on or in an aperture which can be shut off in the wall of the pipe. This can be carried out in such a way that it can, inter alia, be ensured that the flexible pulling element is held well in the centre of the duct, and that it is thus

ensured that the flexible pulling element is not severed through contact with a sharp edge of the generally very thin sheet material of the pipe wall near the edge of the aperture in the pipe. The invention will be explained in greater detail with reference the drawings, which show a number of non-limiting examples of embodiments. In the drawings:

Fig. 1 shows a partially cut-away pipe with a treatment element according to the present invention disposed therein, in perspective view;

Fig. 2 shows a preferred embodiment of the treatment element according to the present invention, in perspective view;

Fig. 3 shows another preferred embodiment of the treatment element according to the present invention, in perspective view;

Fig. 4 shows an alternative embodiment of the treatment element according to the present invention, in perspective view; Fig. 5 shows a view in cross-section of the pipe 1 at the position where the flexible pulling element is passed through.

Fig. 1 shows a part of a pipe, for example a ventilation duct of an air conditioning system for buildings. Such pipes are generally designed in a light construction, and the support of such pipes is generally not designed for a higher load than purely the weight of the pipe itself. In addition, such pipes generally have poor accessibility, and during the original installation are hardly provided with access hatches or inspection doors. It is therefore generally necessary for access doors to be fitted first in such a pipe 1 of an air conditioning system before the treatment of the inside can be started. Due to the fact that with the present invention the pipe can be treated without disruption over a long length from one access aperture, the costs of providing the necessary access doors remain limited. A medium flows through the pipe part 1 in the direction of the arrows.

In the cut-away section of the pipe part 1 is a treatment element 2 for carrying out the method according to

the present invention. The medium flowing through the pipe part 1 thrusts on the inside against the treatment element 2, as a result of which a flexible wall part 3 of the treatment element 2 running in the peripheral direction is pressed outwards against the wall of the pipe 1. The treatment element 2 is connected to a flexible pulling element 4, which is shown in all figures by a dashed and dotted line. It runs at a suitable point through an access aperture through which treatment element 2 can be inserted to the outside, and can be paid c^t and hauled in there with a reel. A solution to prevent tne flexible pulling element from being severed by the generally sharp edges of such an access aperture is shown in Fig. 5. A bracket 16 is fitted projecting inwards into the inside of the pipe 1. For this, the bracket 16 is fixed on a cover plate 15 which is fixed along or on the edge of the aperture in the pipe 1. A guide wheel 17 over which the flexible pulling element 4 can be guided is fitted on the end of the bracket 16. This pulling element 4 runs from a pulley 18 outside the pipe 1 in the manner shown through the cover plate 15 and into the pipe 1. It is preferable for the measurement of the bracket 16 and the guide wheel 17 to be such that the flexible pulling element 4 in the tensioned state runs approximately in the centre point of the cross- section of the pipe 1. Through paying out or hauling in the flexible pulling element 4 it is possible to make the treatment element 2 move along with the medium stream in the direction of the arrows in Fig. 1, to stop it, or to make it move in the opposite direction to the direction of flow of the medium. In this process it will generally have to be ensured that the velocity difference between the treatment element 2 and the medium present upstream of the treatment element 2 is prevented from being zero. If this is prevented, the wall part 3 of the treatment element 2 will be pressed against the wall of the pipe in all circumstances. Due to the abrasive action thereof on the wall of the pipe 1, said wall can, for example, be cleaned and have the dust, dirt and the like present removed.

So-called guide vanes 10 are also often situated in bends in such a pipe 1. In the pipe shown they are achieved

by means of depressions provided in the wall of the pipe 1. If for the method according to the present invention use is made of treatment elements such as those shown, for example, in Figs. 2 and 3, it is now even possible for the treatment element, due to its flexibility, to pass through an opening between two of such guide vanes 10 and then to resume its ormer shape and continue its passage through pipe 1.

Fig. 2 shows a preferred embodiment of the treatment element 2 for carrying out the method according to the present invention. This preferred embodiment is formed by a slightly flexible bag with along a part of its length an outer surface 3 treating the inside wall of the pipe. The bag is connected to the edge 5 of the open end 6 by a flexible pulling element 4. Relatively short pulling elements are fixed at regular intervals to the edge 5 of the open end 6 along the periphery of the opening 6, these short pulling elements merging at their other end into a point 7 where they are fixed to the flexible pulling element 4. The fixing to the edge 5 of the open end 6 of these relatively short pulling elements 8 can be made detachable, for example by means of snap hooks which are fixed on the short flexible pulling elements 8 and are fastened to pull rings fitted in the edge 5 of the open end 6. The bag of the treatment element 2 shown in Fig. 2 is flexible for radial compression at least over part of its length and in any case near the open end 6. The bag is provided along a part of its length with an outer surface 3 treating the inside wall of the duct and being of at least approximately constant cross-section over the length, which outer surface 3 in the example shown is provided with an abrasive material 9. This can be, for example, material of the type used in the home for cleaning dishes or pans. Such an abrasive surface gives good results for cleaning off dust, dirt and the like from the inside of a pipe. Past the treating outside surface 3 the bag merges into a part 11 of reducing cross-section, ending in an aperture 12, the purpose of which is to allow through the medium. The shape shown means that the bag of the treatment element 2 will bulge out when it is flowed through by medium passing from inflow aperture 6 to outflow aperture 12. Along the edge

of outflow aperture 12 a cord 13 is sewn into the edge of the outflow aperture, which makes it possible, through adjusting the cord 13 so that it is tighter or looser, to increase or reduce the cross-section of the outflow aperture 12. The treatment element 2 can also be used for carrying out the method according to the present invention if the outflow aperture 12 is completely shut off or is omitted, but the use of such an aperture is preferred.

Fig. 3 shows a different embodiment of the treatment element 2 for carrying out the method according to the preseπr invention. In this case the periphery of the bag of the treatment element 2 is adapted to a pipe 1 with rectangular cross-section, instead of with a circular cross- section as was the case in the preceding example. For the rest, the treatment element has the same parts as the treatment element of Fig. 2. This means that a treatment element 2 adapted to the specific pipe can be manufactured cheaply for any type, any modified shape and any measurement of pipe 1. With the embodiments shown in Fig. 2 and Fig. 3 of the treatment element 2 for carrying out the method according to the present invention it is possible for a treatment element 2 to be made totally flexible, so that it is easily possible to pass places with great cross-section changes in the pipe 1, such as at the position of the guide vanes 10.

Fig. 4 shows an alternative embodiment of the treatment element 2, which is not completely axible. A shape- retaining flow element 14 J .>W projects into the inflow ape--ure 6 of the bag. This flow element 14 is also attached in .e manner shown to the flexible pulling element 4, as a result of which the flow element 14 cannot move in the lengthwise direction relative to the outer surface 3 treating the pipe 1. As shown, the flow element 14 has a conical front side and an aerodynamically shaped rear side. The part 11 of the treatment element 2 situated past the treating outer surface 3 in this embodiment does not have a reducing cross- section. This part does end in an aperture 12. The flow element 14 in the treatment element 2 will now give the desired thrust effect, so that the treating outer surface 3

will be pressed against the wall of the pipe 1. For additional thrust the cross-section of the aperture 12 can still be reduced by means of the cord 13. It is also possible to make an embodiment of the treatment element 2 as shown in Fig. 4 without flow element 14. The outflow aperture 12 will then always have to be made smaller than the inflow aperture 6 by means of the cord 13, or any other suitable means. The manufacture of such a treatment element is now even further simplified, through the fact that only two opposite edges of, for example, a rectangular piece of cloth need be fastened to each other, thus producing a sleeve-shaped element to which only cord 13, treatment surface 9 and, for example, along the edge 5 of the opening 6 pull eyes need be fastened.

Of course, other embodiments of the treatment element 2 are also possible. For example, other forms can be chosen for the flow element 14. The method of fastening the treatment element 2 to the flexible pulling element 4 can also be carried out in a different way. In addition, in the case of treatment elements for pipes with a circular cross-section it is possible to fit, for example, fins which are exposed to the flowing medium and are disposed in such a way that they set the treatment element 2 in rotation. This could produce an additional treating action. It could also be beneficial to make the edge of the aperture 12 elastically stretchable, for example by using an elastically stretchable cord 13, so that the ratio between the size of the inflow aperture 6 and the outflow aperture 12 of the treatment element 2 can automatically adapt within certain limits to changes occurring in the flow pattern. The present invention can, of course, also be very serviceable for treatments such as cleaning, coating, painting or covering the inside of, for example, an oil pipeline. It will then, of course, be necessary to remove the oil from the oil pipeline and temporarily create a flow of a compressible medium therein. Gas pipelines and all kinds of other pipes can be treated easily and effectively in this way. The desired flow of compressible medium can be generated by an external generator for a medium flow, for example a fan or a compressor. In the case of air conditioning systems for buildings, so-called air

conditioning cabinets are, however, always present. These can be ideal for carrying out the method according to the invention. It is always best in this case when treating the pipe to use these air conditioning cabinets in such a way that air is sucked out of the various living rooms through the ducts to be treated. In some cases the direction of the air flow in the ducts to be treated has to be reversed for this purpose. This is possible in virtually all cases by the temporary use of flexible shunt pipes or bypass pipes which are fitted in such a way that the suction side of the existing air conditioning cabinet extracts from the pipe to be treated at that moment. If different air conditioning "-abinets are present in the same location or in the same room, it is preferable for this solution to connect the pipe to be treated to the air conditioning cabinet with the largest capacity. It is also an advantage to use the space in which the air conditioning cabinets are situated for collecting the material removed from the pipes. This space is then simple to clean later.