The invention relates to a system for connecting energy recovering pipe sections .

Such a system is for example known from NL-8205037. This patent document discloses double walled pipe sections for recovering heat from the soil . The double walled pipe sections can be connected by a joint having interior and exterior sleeves. The sleeves are positioned over the double walled pipe sections and can be attached thereto by using for example adhesive.

The system of NL-8205037 is preferably not used in a sanitary sewer, as the central flow passage defined therein comprises obstacles, such as for example the stepped inner sleeve. This inner sleeve will increase the risk of clogging when used in a sewage system. In addition, sanitary sewage pipes are often located underground, which means that repairing clogged pipes and/or maintenance thereto has a lot of impact with regard to work load .

It is therefore an object of the present invention to provide a system for connecting pipe sections for recovering energy, which system is used for recovering energy from sewage.

With the system according to the present invention as defined in claim 1 a sewage flow path is provided which minimizes the risk of clogging and therefore minimizes repair and maintenance work. The system of the present invention provides an obstacle- free flow path for sewage.

Advantageous embodiments of the present invention can be found in the dependent claims. To explain the invention in more detail, exemplary embodiments thereof will hereinafter be described with reference to the accompanying drawings, wherein: Figure 1 shows a section of a first embodiment of the system for connecting energy recovery pipe sections according to the present invention;

Figures 2a and 2b show schematic views of parts of the system shown in figure 1;

Figure 3 shows a section of a second embodiment of the system according to the present invention;

Figures 4a and 4b show a schematic view of a third embodiment of the system according to the present invention; In this description, identical or corresponding parts have identical of corresponding reference numerals .

Figures 1, 2a and 2b show (parts) of the system 1 of the present invention. The system 1 shown in figure 1 comprises at least two sanitary sewage pipe sections, comprising a first pipe section 3, and a second pipe section 5. Each pipe section having pipe walls 8 with longitudinally extending fluid passages 7 therein for recovering energy from sewage (not shown) flowing through central passageways 6 of the pipe sections 3,5 in a direction indicated with arrow PI. The pipe sections are made of plastics, particularly thermoplastics. The pipe walls 8 are provided with longitudinal passages 7 extending parallel to the center line of each pipe section. The passages also known as channels are regularly divided over the circumference of the pipe sections and preferably each channel has an identical cross section. The channels extend parallel to each other and parallel to the central passageways 6. Preferably, an inner side of the pipe walls provides the inner wall of the pipe section 3 , 5 wherein within the inner wall the fluid passages 8 extend.

The system 1 further comprises a coupling device or means 11 for coupling the first 3 and second pipe sections 5. The pipe wall end parts have spigot ends 15. The spigot ends 15 provide dead endings for the fluid passages 7 in pipe walls 8. To establish a fluid connection between the fluid passages 7 of the first pipe section 3 and the fluid passages 7 of the second pipe section 5, the coupling device 11 incorporates a fluid connector 13. The fluid connector 13 comprises a channel 17 to be connected to openings 19, 20 in the pipe walls 8. The fluid connector 13 will be discussed in more detail below with reference to figure 2b.

The coupling device 11 comprises an annular rim 21, which is attached to an inner annular shell 38 of the coupling device 11. The rim 21 is provided with a radially inner side 23. This radially inner side 23 of the coupling device 11 together with inner pipe walls 28 define a sewage flow passage 30 of the system 1. The sewage flow passage 30 of the system 1 according to the present invention provides a smooth sewage flow path, which extends in the direction of arrow PI. As can be seen in figure 1 the flow path is without obstacles, such as indentations and/or protruding parts which increase the risk that the flow path is clogged.

The radially inner side 23 is flush with the inner pipe walls 28 such that the diameter Dl of the sewage flow path defined by the radially inner side 23 of the rim 21 is identical to the central passageways diameter D2, i.e. the diameter defined by the inner pipe wall 28.

The rim 21 further comprises two opposing contacting sides 31, 33, which are positioned against spigot end parts 15 of the pipe sections 3, 5. Preferably, the rim is made of elastic material or plastic material, e.g. PVC such that spigot end parts 15 can be firmly pushed against the rim 21, minimizing the transition effects between the rim 21 and the spigot end parts 15 such that an almost seamless transition is provided there between. The coupling means 11 further comprise a number of annular elastomeric seals 41, 43, 45, 47 for coupling the pipe sections 3, 5. In addition, the seals 41, 43, 45, 47 provide a fluid tight connection between the coupling means 11 and the pipe sections 3, 5.

Further, figure 1 and 2a show a sleeve or an annular element 51 arranged or able to be arranged over the first pipe section 3 and attached thereto by means of annular elastomeric seals 53, 55. The annular element 51 shows an inlet 57 to provide for example fluid in the direction of arrow P2 through opening 59 into the fluid passages 7. It is also possible to use inlet 57 as an outlet, i.e. to remove fluid from the fluid passages 7. The annular element 51 further comprises a second inlet 61 positioned above another opening 60 in the pipe wall 8. The openings 19, 20, 59, 60 can be prefabricated or provided in situ.

In figure 2b the coupling means 11 is shown in more detail. The cylindrical coupling means 11 comprises an outer annular shell 71 and the inner annular shell 38 connected to the outer annular shell 71 by means of clamping rings 90 located in recesses 92 in the outer annular shell 71. Sealing elements 75, 76 provide a fluid tight connection between outer annular shell 71 and the inner annular shell 38. The inner annular shell 38 is provided with openings 81 forming part of channel 17. The other part of the channel 17 is provided by the space 80 between the outer annular shell 71 and the inner annular shell 38. Between openings 81 a part 83 of the annular shell 38 is made thinner than other parts of the annular shell 38. By means of thinner part 83 the fluid from fluid channels 7 is able to flow to the openings 81, indicated by arrows P3 and P4. Part 83 in combination with fluid connector means 13 provides a fluid mixing effect of the fluid from channels 7 such that the heat exchange between the fluid and the sewage can be optimized. In figure 3 a second embodiment of the system 101 according to the invention is shown. The pipe sections 3, 5 comprise end parts 115. The end parts 115 are wide end parts, i.e. these end parts have a larger diameter than the rest of the pipe sections. These end parts 115 are provided with seals 141, 143, 145, 147. The pipe sections are coupled by means of a coupling device or coupling means 111. Coupling means 111 comprise an outer part 111A and an inner part 111B, which are connected to the end parts 115. The channel 117 is integrated in the coupling means 111, and the channel 117 provides the fluid connection between the fluid passages 7 of the pipe sections 3, 5.

Clamping rings (not shown) can optionally be moved over the outer side 111A of the coupling means 111 for providing a radial inward clamping force to prevent that the end parts 115 move relatively to the coupling means 111.

The coupling means 111, more in particular the inner part 111B of the coupling means 111, define together with the central passageways of the pipe sections in the direction of arrow PI a sewage flow passage 130 of the system 101. In the sewage flow passage 130 the inner part 111B of the coupling means only has one radially inner side 123 extending parallel to the flow direction of the sewage indicated by arrow PI.

The shape of the inner part 11IB corresponds to the shape of the end parts 115 of the pipe sections 3, 5. In this manner the system 101 comprises a smooth or continuous i.e. without steps sewage flow path without obstacles such as indentations or protruding parts. In addition, the radially inner side 123 is flush with the inner pipe walls 28 such that the diameter Dl of the sewage flow path defined by the radially inner side 123 is identical to the central passageways diameter D2, i.e. the diameter defined by the inner pipe wall 28. Figures 4a and 4b show another embodiment of the system 201 of the present invention. Figure 4b shows the system 201 not fully coupled, i.e. to finish the coupling operation the pipe sections 3, 5 have to be moved closer to each other over a distance indicated with A in figure 4b. The parts of the system 201 shown in the schematic view of figure 4b are not drawn to scale and the distances shown between certain parts may differ from the actual distances. In system 201 the coupling device or coupling means 211 are provided by the pipe wall end parts, wherein the pipe wall end part of the first pipe section 3 is designed as a female coupling part 215A and the pipe wall end part of the second pipe section 5 is designed as a male coupling part 215B. The fluid connector 213 are provided by an external channel 217 and two annular elements 251, which connect the channel 217 to the fluid passages 7 in the pipe sections 3, 5. In other words, in system 201 the fluid connector means are not incorporated in the coupling means 211. In a fully coupled state (not shown) the coupling means 211, more in particular male coupling part 215B, together with the central passageways 6 of the pipe sections 3, 5 form a sewage flow passage 230 of the system, wherein in the sewage flow passage 230 of the system 201 the coupling means only have one radially inner side 223 extending parallel to the flow direction of the sewage. As the radially inner side 223 is flush with the inner pipe walls 28, the diameter (not shown) of the sewage flow path defined by the radially inner side 223 is identical to the central passageways diameter (not shown), i.e. the diameter defined by the inner pipe wall 28.

In the embodiments of the system 1, 101, 201 a sewage flow path 30, 130, 230 is provided without radially inwardly protruding parts of the coupling means 11, 111, 211 with respect to the inner pipe wall 28 of the pipe sections 3, 5. More in particular the system 1, 101, 201 comprises a sewage flow path with a constant diameter over substantially the complete length of the system seen in the direction of flow indicated by arrow PI .

The coupling device 11 for coupling first and second pipe sections comprise a rim 21 providing only one radially inner side in the flow path of the sewage, which radially inner side extends parallel to the flow direction of the sewage and the rim is dimensioned such that the radially inner side is flush with the inner pipe walls 28 such that the diameter Dl of the sewage flow path defined by the radially inner side 23 of the rim 21 is identical to the central passageways diameter D2, i.e. the diameter defined by the inner pipe wall 28. Preferably, a fluid connector is integrated in the coupling means, wherein, if the pipe sections are coupled by means of the coupling means, the center line of the channel of the fluid connector means does not coincide with the center lines of the fluid passages as can been seen in the embodiments shown in the figures. Preferably, the main part of the channel, i.e. the part of the channel that extends above the transition between the pipe sections, comprises a center line extending parallel to the center lines of the fluid passages in the pipe walls.

The system for connecting energy recovering pipe sections comprises:

- at least two sanitary sewage pipe sections comprising a first and a second pipe section with central passageways, each pipe section having pipe walls with longitudinally extending fluid passages therein for recovering energy from sewage flowing through the central passageways,

- fluid connector means for connecting the fluid passages of the first and second pipe section,

- coupling means for coupling the first and second pipe sections, said coupling means define together with the central passageways of the pipe sections a sewage flow passage of the system, wherein in the sewage flow passage of the system a radially inner side of the coupling means only have one radially inner side extending parallel to the flow direction of the sewage.

In the system 1 it is also possible to use an external channel provided between two annular elements 51, instead of the channel 17 integrated in the coupling means 11.

The side by side arranged fluid passages are separated from each other with longitudinally extending ribs, which extend between the inner and the outer side of the pipe section. The fluid passages are circumferentially regularly divided in the pipe walls of the pipe sections.

The sleeve 351 does not have a pipe-coupling function. The same applies for the annular element 51, 251. In other words, the sleeves 51, 251, 351 can not be used to provide a mechanical connection or coupling between two pipe sections. A sleeve can be part of the fluid connector for connecting the fluid passages of the first and second pipe section or the sleeve can be used to introduce or remove fluid from the pipe sections.

The invention can be extended beyond the presently presented claims. Note that a number of modifications to what has been presented above is not inconceivable. For instance, instead of having fluid passages extending within each inner pipe wall, it is also possible to have within each pipe wall at least one fluid passage extending for recovering energy from sewage flowing through the central passage way. It is also conceivable that the fluid passages, or at least one fluid passage, extend (s) in a helical fashion.