DRIP IRRIGATION PIPE WITH EMBODIED CONTINUOUS CONDUIT FOR PRESSURE REDUCTION AND METHOD OF PRODUCING SAME

Abstract: This invention concerns a drip irrigation pipe with embodied continuous conduit for pressure reduction and method of producing same. The drip irrigation pipe has a main pipe (1) for supplying water to a pressure reduction conduit (2), and the conduit is attached to the main pipe. The conduit has water inlet openings (3) at intervals, it ensures pressure drop and flow strangulation with successive narrowings-widenings (22, 24) and/or flow diversion (32, 36, 40) and it has outlet means (4) for supplying water in small quantities to the environment for irrigation.

Description: DRIP IRRIGATION PIPE WITH EMBODIED CONTINUOUS CONDUIT FOR PRESSURE REDUCTION AND METHOD OF PRODUCING SAME The invention concerns a drip irrigation pipe having means for partially obstructing the water flow in order to achieve a "strangulation" of the water flow. Such strangulation is required to adjust the amount of the water flowing out of the pipe for irrigation purposes to a relatively small amount. The problem of drip irrigation has been faced by the up- to-date technology mainly by inserting independent drippers in the pipe. The insertion is done either with the use of a special mechanism on-line or manually depending on the type of the drippers. These drippers have a meander or helical path in which the water strangulation (and therefore the drip irrigation) is achieved. A drip irrigation pipe with strangulation channel has been manufactured for short-life pipes. Also in this case the strangulation is done with flow diversion through small cross-sectional areas. The structures using independent drippers • have to achieve the necessary strangulation in a relatively short length of the flow path (which is limited by the length of the dripper) and therefore the crosse-sectional area of this flow path through the dripper has to be reduced. The existing systems of short-life pipe suffer from the same disadvantage of small cross—sectional areas. Practically, this results flow interruption (blocking) by even small quantities of particles or minerals deposits The present invention is based on a new concept relating to a special pressure reduction conduit which is secured to or formed integrally with the (main) pipe which supplies the water. According to the present invention the special conduit has an irregular form, i.e. the conduit is successively narrow and then wide, by providing narrow and wide passages in alternating fashion; or the special conduit employs means for flow diversion; or the special conduit uses a combination of narrow/wide passages and flow diversion. The special conduit for pressure reduction has a tubular or special profile cross section and is running along the whole length of the main pipe internall r or externally. Thus reduction of the water pressure is achieved using successive narrowings-widenings, diversion of the water flow direction or combination of the above inside the embodied conduit, while assuring small water supply inside the embodied pressure reduction conduit using at the same time large cross—sectional areas in such a way that the interruption of flow due to particles or minerals is avoided. The flow out of this small water supply will be in small quantities through holes of proper dimensions and at proper distances which will be opened during the production of the drip irrigation pipe with embodied pressure reduction conduit. The water will enter the embodied pressure reduction conduit through holes of proper dimension and shape which will act as filter well in order to prevent particles from entering the conduit. The scope of the invention includes the way of strangulation which is achieved with successive narrowings-widenings in order to achieve pressure reduction and decrease of water flow for drip irrigation in such a way that relatively large cross-sectional areas can be used along the strangulation path, for decreasing the probability of blockings or flow interruptions due to particles and minerals. In addition the scope of the invention includes the method of production of the special conduit for drip irrigation and the method of production of the drip irrigation pipe. The proposed way for drip irrigation with an embodied continuous conduit for pressure drop using narrowings—winderings , flow diversion or their combination, has the advantage, over the existing systems mentioned above, in that since it can have larger strangulation path length, it can also have larger cross sectional areas of this path avoiding therefore flow interruption due to particles or minerals deposits . According to the proposed invention a continuous conduit will be embodied in the main supply pipe internally or externally having constant or variable flow section where using successive narrowings-widenings, flow diversion or their combination, pressure drop of the water is going to be achieved. When the continuous conduit is embodied internally, it will be supplied with water through groups of holes which will be opened internally at proper distances and these holes will act as a filter, while it will supply small quantities of water through holes which will be opened on the circumference of the main pipe at proper distances from the entrance holes of the continuous conduit. When the continuous conduit is installed externally it will be supplied with water from the main pipe through groups of holes which will be opened at proper distances on the circumference of the main pipe and will act as filter, while it will supply small quantities of water through wholes which will be opened on the continuous conduit at proper distances from the entrance holes. The use of the continuous conduit for pressure reduction has the advantage that the strangul tion cross-sectional area is larger and therefore the probability of blocking or flow interruption is considerably reduced, in relation to the existing drip irrigation systems. The provision for use and installation of a seperate special conduit for pres¬ sure reduction allows this special conduit to be designed in such a manner that the way of strangulation is optimi¬ zed using successive narrowings-widenings, flow diversion or their combination thus achieving both strangulation and self-cleaning from particles or minerals deposits, in contradiction to the existing short-life systems where only flow diversion is applied using small cross-sectional areas and therefore the flow interruption is not avoided. Further advantage of the use of separate special continu¬ ous conduit for pressure reduction is the possibility of installing more than one conduits in the same main pipe in the case that the flow-out distances require small strangulation length. The successive flow-out holes can belong to different conduits in such a way that the strangulation length is the proper one. In addition using the continuous conduit, the production of the long life drip irrigation pipe is simplified because the special system for the insertion of the drippers used in the existing systems is not required. The continuous conduit for pressure reduction may be embodied in different forms and shapes. According to a preferred embodiment of the invention, the conduit has a cross section which varies along the length of the conduit, thus providing alternating narrowings and widenings. This may be achieved by changing the diameter in step-wise fashion or (alternatively) in wave-like fashion, for example. According to a further preferred embodiment to the invention, the continuous conduit for pressure reduction can have diaphragms or obstacles along its length or it can be without diaphragms according to the demand. Its cross-section can be circular or special profile or generally any proper shape with constant or variable cross-sectional area while the water flow path inside the conduit can be any form which ensures narrowings -widenings, flow diversion or their combination. In addition the distances of the narrowings-widenings and flow diver¬ sions as well as their rest geometrical specifications can be uniform or non-uniform or to vary in any way along the flow path. The conduit can have one or more strangu- ation paths (channels) along its length. Each of them can' ave or not have its own water inlet or outlet wholes, and it can communicate or not (through proper holes) with its neighbour channel(s). In the case that the conduit is profile-shaped it can have a straight channel which runs parallel to the strangulation channel(s). The water enters the strangulation channel (s) from groups of holes opened at proper distances and after running some length it flows in the straight channel of the conduit. Then the water can flow out to the environment through holes which can be opened at any point of the straight channel. This structure reduces the problem of blocking due to insects. Any of the above shapes the conduit has, it will always be embodied in the same way in the main pipe and it will be continuous. The invention will be explained subsequently in more detail with respect to the accompanying drawings , in which Fig. 1 shows an axial cross section of a drip irrigation PΪP e having a special conduit according to the present invention where: Fig. la to Fig. Ik show preferred embodiments of the special conduit according to the present invention, where: Fig. la shows an axial cross section of a conduit having a step-wise varying diameter; Fig. lb shows an axial cross section of a conduit having a wave-like varying diameter; Fig. lc shows an axial cross section of a conduit having a constant outer cross-section and having diaphragms inside; Fig. Id shows an axial cross of another embodiment of a conduit according to the present invention having diaphragms with sharp edges; Fig. le shows a detailed part, in enlarged scale, of Fig. Id; Fig. If shows a cross section in a direction perpendicular to the longitudinal direction, of a conduit according to the present invention having a circular cross section; Fig. Ig shows cross sections, of other conduits according to the present invention having rectangular cross sections and Fig. lh shows two cross sections similar to Figs. 'I of other conduits according to the present invention having cross section in the shape of a section of an arc; Fig. li and lj show axial cross sections of two further embodiments of the conduit in the case when there exist diaphragms forming angle different than 90° with the wall of the conduit. Fig. Ik shows an axial cross section of still another embodiment of the conduit for the case where the distances between the diaphragms are such that only water flow diversion is involved. Fig. 2 shows a cross section through the pipe of Fig. 1 in the direction perpendicular to the axial direction thereof; Fig. 3 shows a cross section through another embodiment of a pipe according to the present invention in a direction perpendicular to the axial direction thereof; Fig. shows a cross section through the pipe of Fig. 3 along the plane indicated by arrows in Fig. 3; Fig. 5 shows a view of a manuf cturing apparatus for producing the pipe according to the present invention; Fig. 6 shows a cross section of still another embodiment of the pipe according to the present invention in a direction perpendicular to the axial direction thereof where the conduit has a straight channel parallel to the strangulation channel. Fig. 7 shows a cross section through the pipe shown in Fig.6 and through the plane indicated by the arrows. Fig. 8 shows a cross section , similar to Fig. 6, of still another embodiment of the pipe according to the present invention having a conduit embodied at the outside of the main pipe. Fig. 9 shows a cross section, similar to Fig. 8, of still another embodiment of the pipe according to the present invention where there are two conduits embodied at the inside surface of the pipe; Fig. 10 shows a cross section, similar to Fig. 9, of still another embodiment of the pipe where the conduit has two strangulation channels parallel to each other. Fig. 11 shows a cross section through the pipe shown in Fig. 10 and along the plane indicated by arrows in Fig. 10; Fig. 12a shows a schematic axial cross section of a pipe according to the present invention having two strangulation channels like in figs 9 and 10, and the water flow is indicated. Fig. 12b shows schematically another cross section, of the pipe of Fig. 12a, in a different view where the water flow is indicated. Fig. 12c shows schematically a cross section, similar to Fig. 12a, of still another pipe according to the present invention, showing one conduit comprising three strangulation channels. Fig. 12d shows a different cross section of the pipe of Fig. 12c in a different view where the water flow is indicated. Fig. 13 shows a schematic side view of a conduit according to the present invention in the axial direction thereof showing the inlet and outlet sections, respectively, of tube shaped conduit. Fig.13a is similar to Fig. 13 for a profile shaped conduit, while fig. 13b is similar to fig. 13a but the inlet and outlet openings have the form of a slit. Fig. 14, 15 and 16 show cross sections of three further embodiments employing the continuous conduit in combination with plastic film. In Fig. 1 and Fig. 2 is shown a long/itudinal section and a section in a direction perpendicular thereto, respectively, of a drip irrigation pipe 1 according to the present invention. Pipe 1 has a circular cross section, and a pressure reduction conduit 2 according to the present invention is secured to the inside surface of the pipe 1. Supply water flows into pipe 1, and some of this water enters through an inlet hole 3 shown in figure 1 to the conduit 2. The conduit 2 has narrowings and widenings in alternating fashion as it will be explained in detail below. In the embodiment shown in fig. 1,2 the conduit 2 has straight wide passages (widenings) followed by straight narrow passages, (narrowings) such that a wide passage is followed by a narrow passage, and vice versa. The water in the conduit 2 flows along the conduit, to the right in fig. 1," and some of this water leaves the conduit 2 and the main pipe 1 through an outlet hole 4 for irrigation purposes. The inlet hole 3 and the outlet hole 4 in fig. 1 are shown only indicatively. Several inlet holes and/or outlet holes may be provided, as will be explained in more detail below. The relative positions of the inlet holes and outlet holes, respectively, depend on the specific application and are shown only indicatively in fig. 1. Figs, la to Ik show specific details of several embodiments of the pressure reduction conduit according to the present invention. Fig. la shows the conduit 2 already shown in fig. 1 again for comparison purposes. As shown in fig. la, a narrow passage indicated by "MIN" of the conduit 2 is followed by wide passage, indicated by "MAX", and so on in the direction of the flow of the water indicated by the thick arrow in fig. la. Fig. lb shows another embodiment of a conduit 20 having narrow passages 22 and wide passages 24. The walls of the conduit 20 are wave-like shaped such that corrugations appear at regular intervals. Fig. lc shows still another embodiment of the conduit 30 having the shape of a profile with diaphragms arranged at proper distances. In more detail, water enters conduit 30 at the left hand side thereof, as indicated by the thick arrow in fig. lc, and flows to the right until the flow is obstructed by a first diaphragm 32 and the wall of conduit 30. The area of gap 34 corresponds to the area of the narrow passage 22 of the conduit 20 shown in fig. lb, or to the area of the narrow passage indicated by "MIN" of the conduit 2 shown in fig. la, respectively. The water after gap 34 of conduit 30 then enters into the next wider passage thereof and is again obstructed by a further diaphragm 36. Diaphragm 36 extends from the opposite wall of the conduit 30, as compared to diaphragm 32, leaving open only a small gap 38 similar to gap 34. Diaphragm 36 is followed, in the direction of flow of the water, by a further diaphragm 40 similar to diaphragm 32 which leaves open a small gap 42 similar to gap 34. The same procedure is followed along the whole length of the pipe. Thus, in the conduit 30 shown in fig. lc narrowings are employed by gaps (34, 38, 42) and also a diversion of the direction of water flow, which results from the alternating arrangement of diaphragms 32, 36, 40 Fig. Id shows a still further embodiment of a conduit 50 according to the present invention. Conduit 50 is similar to conduit 30 shown in fig. lc in that conduit 50 also has diaphragms 52, 54, 56. The gaps 34, 38, 42 in " fig. lc, however, are formed between the tip of the respective diaphragm and the inner surface of the wall of conduit 30. In the conduit 50 shown in fig. Id, similar gaps are formed between the tips of diaphragm 52, 54, 56, respectively, and the tips of shorter diaphragms 58, 60, 62, respectively. Thus, the diversion of the direction of the water flow is less in the embodiment shown in fig. Id than in the embodiment shown in fig. lc. The embodiment of the conduit 50 shown in fig. Id may present further advantages, if the edges of the diaphragm sections which are aligned with each other are formed as sharp or pointed edges, as shown in an enlarged view in fig. le for the diaphragm sections 52, 58 of fig. Id. The sharp edges of the diaphragm sections 52, 58 serve to reduce any danger that particulate matter or minerals might be trapped in the narrowing between the two diaphragm sections. Firstly, the danger of any particulate material or minerals being trapped between two sharp or pointed edges is very small in itself, because the sharp edges have a very small lenght in the axial direction of the water flow. Secondly, any particulate matter or mineral which is nevertheless trapped between these two edges tend to be removed due to the pressure applied on them and to their poor atachmeπt on the walls of the narrowing in combination with the local increase of speed. Fig. If shows a cross section through a conduit having a circular cross section, for example the conduit 2 or the conduit 20 mentioned above. In this respect it is to be noted that conduit 2 and conduit 20 are circular incross section, the cross section taken along a plane perpendicular to the axial extension of these conduits. Fig. Ig shows two cross sections taken along a plane perpendicular to the axial direction of conduits 70, 74 and it is to be noted that, for example, the above—mentioned conduits 30 and/or 50 may have such rectangular cross section. Fig. Ih shows still two more embodiments of conduit 72, 76 whose cross sections, taken along a plane perpendicular to the axial direction of the conduits 72, 76 have the shape of the section of an arc segment. The conduits shown in fig. lc or fig. Id, respectively, may have a cross section like conduits 72, 76 shown in fig. Ih. Fig. li shows still another embodiment of the conduit 250 according to the present invention where there are diaphragms- 252, 254, 256 on the one wall of the conduit and 258, 260, 262 on the other, in such a way that the said diaphragms form an angle different than 90° with the respective wall. Each diaphragm 252, 254, 256 forms with one of 258, 260, 262 gaps 264, 266, 268 respectively, for the water strangulation with the use of narrowings-widenings. Fig. lj shows still another embodiment of the conduit 270 where there are diaphragms 272, 274, 276 similar to the diaphragms 32, 36, 40 of fig. lc, but they form an angle different than 90° with the respective walls of the conduit 270. The gaps 278, 280, 282 operate in a similar manner like 34, 38, 42 in fig lc in such a way that we have both narrowings-widenings and water flow diversion. Fig. Ik shows still another embodiment of .the conduit 300 where there are diaphragms 302, 304, 306 and 308, 310, 312 similar to the diaphragms 32, 36, 40 of fig. lc but where the distance between successive diaphragms is of the order of the respective gap 314, 316, 318, 320, 322, 324. Hence essentially we have only water flow diversion and not narrowings-widenings. Figs.3 and 4 show an embodiment of the pipe according to the present invention where the pipe 10 has a shape similar to pipe 1 shown in fig. 1, but where conduit 12 has a shape,for example, as in fig. Ih, without the upper wall (profile shape, 76) and where diaphragms 13, 14, 15 are provided which are similar to diaphragms 32, 36, 40 of conduit 30 shown in fig.lc. In more detail, diaphragms 13, 14, 15, and so on, extend in an alternating fashion from the side walls of conduit 12, leaving a gap 16 between diaphragm 13 and the side wall of conduit 12, leaving a gap 17 between diaphragm 14 and the opposite side wall of conduit, and leaving a gap * 18 between diaphragm 15 and again the first side wall of conduit 12, respectively. Inlet holes 19 are shown while the outlet holes are not shown in figs. 3 and 4. Respectively the conduit 12 might have diaphragms similar to the diaphragms of the conduit 50 in fig. Id. Fig. 5 shows an apparatus for producing pipe 1 having conduit 2 shown in figs. 1, 2. It is to be noted that the apparatus shown in fig. 5 may be used, employing suitable modifications if required, to produce any one of the of the pipes according to the present invention. The continuous conduit 2 may either be produced at the same time as the main pipe 1, or, alternatively, continuous conduit 2 has already been produced during a previous phase of the manufacturing process, and the conduit 2 is supplied in the production room coiled in jumbo roll. The conduit 2 or 20 shown in figs, la and lb, as well as all the conduits according to the present invention, will be produced with the use of special corrugators. The main pipe 1 is extruded from a suitable plastic material through an extruder 6 to an angular extrusion head 7 similar to the ones used for cable manufacturing. The continuous conduit 2 is supplied to the extrusion head 7 and enters the extrusion head through a second inlet thereon. Before conduit 2 enters the extrusion head 7, holes serving as inlet or outlet holes are drilled into the walls of conduit 2 by means of a suitable drilling mechanism 8. Alternatively, the holes may be drilled into conduit 2 during the previous production phase thereof. When the conduit 2 is installed internally of the main pipe 1, these holes are used for the entrance of the water into the conduit. The drilling is performed at proper locations, depending on the type of the pipe which is to be produced. When the conduit 2 has entered the extrusion head 7, is pulled by the flow of plastic material adhered to the outer surface of the conduit due to the irregularities of the outer surface. Then the continuous conduit 2 is installed in the main pipe 1, that is fixed to the surface of the main pipe 1 . The main pipe 1 with the conduit 2 fixed thereto leaves the extrusion head 7, and further downstream another suitable drilling mechanism 9 is provided for drilling holes into the wall of the pipe 1 and the wall of the conduit 2 (when the conduit is of such a shape that it has upper wall). These holes drilled by the drilling mechanism 9 serve as outlet holes for the water for irrigation. If the conduit is to be istalled on the outer surface of the main pipe, the holes of the conduit which either have already been drilled or are drilled during the production of the drip irrigation pipe, are used for the flow out of the water to the environment. In this case, the main pipe is produced, and holes are drilled separately, in order to form entrance holes for the water. Subsequently the conduit will be fixed externally on the pipe. Figures 6 and 7 show a drip irrigation pipe 80 according to the present invention having internally a profile-shaped conduit 82 which comprises a straight channel 86 extending parallel to a "strangulation" channel 84. Water enters into the strangulation channel 84 from the inside of the main pipe 80 through holes 92 provided in the bottom wall of conduit 82. The water flows along channel 84 for a certain distance, and exits from channel 84 through holes 90 into the straight channel 86. The water is distributed from channel 86 through holes 88 in the main pipe 80 to the environment for drip irrigation. As shown in figure 7, strangulation channel 84 is provided with diaphragms and gaps similar to those shown, for example, in figure lc. Straight channel 86 has no diaphragms or obstacles. Figure 8 shows an embodiment of a drip irrigation pipe 100 having one continuous special conduit 102 provided at the outside of the main pipe. This continuous conduit can have any shape according to the present invention. Figure 9 shows an embodiment of a drip irrigation pipe 110 having two continuous profile-shaped conduits 112, 114 arranged at the inside of the main pipe 110. As shown in figure 9, the conduits 112, 114 extend along the axial direction of the main pipe 110. In the same sense more than two such continuous conduits may be installed anywhere inside or outside of the main pipe. Figures 10, 11 show still another embodiment of the drip irrigation pipe with embodied continuous conduit. In the embodiment shown in figures 10, 11, a pro ile-shaped conduit 122 is provided which has two parallel strangulation channels 124 and 126, respectively. In more detail, in this example continuous conduit 122 is embodied to the inside surface of the main pipe 120. This conduit can operate in various manners having the proper form. According to one of these cases water flows from the inside of the main pipe 120 through holes 132 into the (left) strangulation channel 126. After having traversed channel 126 for a certain distance in the axial direction thereof, the water reaches the hole or holes 130 in the partition wall between channels 126 and 124. At this point there is a diaphragm which forces the water to flow through holes 130 to the (right) channel 124 and after having traversed a certain distance to fiow out through hole or holes i28 existing on the outer wall of the main pipe 120. In addition the entrance holes 132 might be on the right channel and the outlet holes 128 on the left. Further, the indermediate holes 130 might not exist, and each channel might have its own inlet and outlet holes instead. In this case each outlet hole of each channel in the middle of the distance which is defined by each pair of holes of the other channel, in such a a3 r that the strangulation length is kept sufficiently big, while we have outlet holes in shorter intervals. Also the conduit might have more than two strangulation channels and it can be installed on the inner or outer surface of the main pipe. These channels might have or not have seperating diaphragms and they can communicate or not communicate to each other. The outlet holes of these channels will be at proper distances. Figure 12a shows, in a very simplified manner, an axial cross section through a part of main pipe 130 having -a conduit 132 similar to the one of fig. 11 while figure 12b shows another view of an axial cross section of the same pipe so that the water flow can be indicated. In this example the conduit 132 has two strangulation channels 152, 154 running in a parallel fashion to each other and is separated in sections by latteral diaphragms like 134, 136, 138. The water flow direction in the main pipe 130 is indicated by the double arrow in fig. 12a. Water from the main pipe 130 enters the conduits sections from points like 142, 146, 148 which are indicated with respective arrows, and it flows until it meets the respective diaphragm. Then the water reverses its flow direction and enters the other strangulation channel 152 of the conduit 132. Finally it flows out of the conduit 132 through holes 140, 144, 150 on the wall of the main pipe 130 which are indicated with arrows. Figs. 12c and 12d show one more embodiment of the drip irrigation pipe 160 according to the present invention. This embodiment is similar to the one shown in figs. 12a and 12b, but the conduit has three strangulation channels (176, 178, 180) . The water enters through points 164, 168. 172 and after running the three strangulation channels 176, 178, 180 between the diaphragms 182, 184, 186 it flows out through points 166, 170, 174. Figure 13 shows a side view of the inlet and the outlet sections, respectively, of the conduit 240 for the case when the conduit has a closed cross section as for example in figs, la, lb, If. Conduit 240 has inlet sections 242 and outlet sections 244 arranged at a suitable distance from the inlet sections 242. Inlet section 242 comprises a group of holes of a first diameter. Outlet 244 comprises a group of holes having a second diameter. The diameter of each of the holes in inlet section 242 is smaller than the diameter of each of the holes of the outlet section 244. Furthermore, the diameter of the each of the holes in inlet section 242 is smaller than each of the gaps or the narrow passages of the conduit according to the present invention. Thus, inlet section 242 effictively serves as filter thus effectively preventing that particles of a size suitable for blocking any of these small passages and/or gaps within the special conduit according to the present invention may be bl ocked . Fig. 13a shows a side view of the inlet and outlet openings of the conduit 230 for the case when the conduit has profile-shaped cross section open from the one side. It is noted that when the conduit is installed on the inner surface of the main pipe it has only inlet section, while when the conduit is installed on the outer surface it has only outlet section because the respective outlet and inlet sections are formed on the wall of the main pipe. For the rest the situation is similar to what described for fig. 13. Fig. 13b shows a view of the inlet and outlet openings of the conduit 340 similar to the one shown in fig. 13a but having . slit shaped inlet and outlet openings instead of hole shaped. Also in this case the width of the inlet slit 342 is smaller than the width of the gap or narrow passage of the conduit in order to act as filter. For the rest the situation is similar to what described for fig. 13 and 13a. Figures 14, 15 and 16 show three further embodiments of the present invention where the continuous conduit is used with plastic film. Figure 14 shows a cross section in a plain perpendicular to the axial direction of a conduit 190. Three walls of conduit 190 are shaped as a U-shape profile, whereas the fourth wall is formed by a film 192 with the use of conventional methods. The conduit of this shane can also be used in the form of segments as independent drip irrigation units . As shown in figure 15, such film may also serve as the main pipe, if no high mechanical strength of the main pipe is required. The special conduit has a U-shaped section 200, and the upper wall of the conduit is formed by a foil 202. Foil 202 is actually a section of a foil 204 which forms the main pipe according to the present invention. Water enters the special conduit 200 in a direction indicated by the double arrow in figure 15 and flows out of the special conduit in the direction indicated by the triple arrow. The connection between film and conduit is achieved with the use of conventional methods. In fig. 16 is shown a case similar to the one of fig. 15 according to the present invention where the conduit 210 has only two side walls (222, 216) which are connected to each other via the flow strangulation diaphragms (218) while the film 214 forms the two other walls 212, 220. With respect to particular advantageous dimensions of the conduits mentioned above, the holes or slits in the inlet sections thereof, for example, the inlet sections (242, 232, 342) preferably have a diameter or width of one millimeter each. Then, the extension of the gaps or narrow passages of the conduits is preferably of diameter 1.5 mm or of cross-section 1,2 mm x 1,2 mm, respectively. The axial distance between two diaphragms is preferably of the order of " 6 mm or 1.3 mm. The size of the conduit is preferably of the order of diameter 3 mm or cross-section 3 mm x 3 mm, for a cross section as described in figures If, lg, Ih for example. Under a water pressure of 1 bar, such a conduit having a length of lm, will output approximately 4,2 liters of water per hour. A straight round pipe with a constant diameter of 3 mm will output more than approximately 120 liters of water per hour under the same conditions. Thus, the pipe according to the present invention is particularly well suited for drip irrigation purposes. It is to be noted, however, that the pipe according to the present invention may b'e used in several other cases where a rather large quantity of a fluid shall be supplied in rather small quantities at a plurality of outlet openings. The preferred material for the pipe and the special conduit according to the present invention is polyethylene of either low or high density (LDPE, HDPE) , the linear polyethylene (LLDPE), the polypropylene (PP) or their mixtures, in mixing with carbon black in proper quantities. It is possible though that any other thermoplastic material could also be used.

Claims: f ~ C L A I M S 1. A drip irrigation pipe, characterized by the following features : a) a main pipe (1) for supplying water b) a pressure reduction conduit (2), c) the conduit (2) being attached to the main pipe (1), d) the conduit (2) having water inlet openings and/or water outlet openings at intervals, e) the conduit (2) having pressure reducing means which include an irregular conduit shape, with successive narrowings (MIN) and then widenings (MAX) , and a flow diversion, or both, f) outlet means (4) for supplying water to the environment for irrigation. 2. A pipe according to claim 1, characterized in that said conduit (2, 20) comprises a series of corrugations (MIN, MAX) for providing said narrow (MIN, 22) and said wide passages (MAX, 24), respectively. 3. A pipe according to claim 1, characterized in that said conduit (30) has diaphragms (32, 36, 40) arranged at the inside of said conduit (30) spaced apart from each other in regular intervals in the longitudinal or axial direction of said conduit, said diaphragms (32, 36, 40) each providing a relatively small gap (34, 38, 42) for the water flow. 4. A pipe according to claim 3, characterized in that said diaphragms (32, 36, 40) are arranged in alternating fashion on opposite inner walls of said conduit (30) for providing a diversion of water flow. 5. A pipe according to claim 3 characterized in that said diaphragms (252, 258; 254, 260; 256, 262) are arranged one opposite to the other in such a way that they form gaps (264, 266, 268) and each diaphragm forms an angle different than 90° with the respective wall of the conduit. 6. A pipe according to claims 3 or 4, characterized in that said diaphragms (52, 58; 54, 60; 56, 62) each comprise two sections which can be either equal or one longer (52, 54, 56) and the other shorter (58, 60, 62) aligned with respect to said associated longer section and spaced apart with respect thereto for forming said gap. 7. A pipe according to claim 6, characterized in that said diaphragm sections (52, 58) each comprise a sharp or pointed edge, said edges being disposed in matually aligned relationship for forming said gap therebetween. 8. A pipe according to claims 3, 4, 6, 7 characterized in - 2 - that each of the said diaphragms (32, 36, 40) forms a 90° angle with the respective wall of the conduit. 9. A pipe according to claims 3, 4, 6, 7 characterized in that each of the said diaphragms (272, 274, 276) forms an angle different than 90° with the respective wall of the conduit. 10. A pipe according to any one of claims 1 to , characterized in that said conduit (2) has an essentially circular cross section in a plane perpendicular to the axial direction of said conduit. 11. A pipe according to any one of claims 1 to 9, characterized in that said conduit (70, 74) has an essentially rectangular cross section in a plane perpendicular to the axial direction of said conduit. 12. A pipe according to claims 1 to 9 , characterized in that conduit (72,76) has a cross section, in a plane perpendicular to the axial direction of said conduit, in the shape of a section of an arc segment. 13. A pipe according to any one of claims 1 to 12, characterized in that said conduit (2, 12) is disposed at the inner surface of said pipe (1, 10). 14. A pipe according to any one of claims 1 to 12, characterized in that said conduit (102) is disposed at the outer surface of said pipe (100). 15. A pipe according to any one of claims 1 to 14, characterized in that said pipe (110) has two or more conduits (112, 114). 16. A pipe according to any of claims 1 to 15, characterized in that said conduit (82; 122) comprises two (84, 86; 124, 126) or more channels extending in mutual parallel relationship along the length of said conduit (82; 122), said channels (84, 86; 124, 126) communicating through at least one opening (90; 130). 17. A pipe according to claim 16, characterized in that said conduit (82) has a straight channel (86) providing essentially no pressure drop and one (84) or more water flow strangulation channels said straight channel (86) having at least one outlet opening (88) for irrigation. 18. A pipe according to claim 16, characterized in that said conduit (122) has two (124, 126) or more water flow strangulation channels. 19. A pipe according to any of the claims 1 to 15 characterized in that said conduit 122 has two (124, 126) - 3/ - or more strangulation channels extended in a mutual parallel relationship along the said conduit 122. The said channels (124, 126) do not communicate to each other and each has its own flow out openings. In this case the openings 130 do not exist. 20. A pipe according to any one of claims 1 to 19, characterized in that said conduit (240, 230, 340) has an inlet section (242, 232, 342) comprising a plurality of holes or slits each having a diameter or width smaller than the minimum space or gap formed inside said conduit. 21. A pipe according to any one of claims 1-20, characterized in that said conduit has a profiled section (190, 200, 210) covered by a plastic film (192, 202, 212, 220) for forming said conduit (190, 192; 200, 202, 210, 212, 220). 22. A pipe according to claim 21, characterized in that said film (202, 204, 212, 220, 214) is adapted to cover said conduit section ' (200, 210) and to form said pipe (204, 214) 23. A method for drip irrigation, characterized in that it provides a substantial water pressure reduction along the axial extension of a water supply pipe and small water supply by providing an irregular flow scheme comprising successive narrowings and widenings, water flow diversion or their combination. 24. A method according to claim 23, characterized in that a circular shape conduit is involved for pressure reduction with its bigger diameter not larger than 5 mm. 25. A method for producing a drip irrigation pipe, in particular a pipe according to any one of claims 1-22, characterized by the following steps: a) forming a special conduit (2) of relatively small cross section with the use of a special corrugator, * b) guiding said conduit to a first inlet of a plastics extrusion head (7) ; c) supplying molten plastic material from a plastics extruder (6) to a second inlet of said extrusion head (7); d) forming said pipe (1) at the outlet of said extrusion head (7) and simultaneously securing said conduit (2) to the wall of said pipe (1). 26. A method according to claim 25, characterized in that water inlet openings are formed in said conduit (2) before it enters said extrusion head (7) . 27. A method according to claims 25 or 26, characterized in that water outlet openings are formed in said pipe (1) and/or in said conduit (2) after said pipe (1) has left said extrusion head (7). 28. A method according to any one of claims 25 to 27, characterized in that said conduit is formed immediately before it enters said extrusion head (7) with the use of a special corrugator. 29. A method according to any of the claims 25 to 27 characterized in that said conduit is produced before the main pipe during another production stage with the use of a special corrugator.

Inventors: LEBIDAKIS IOANNIS, PUST DETLEV A W, LEBIDAKIS, IOANNIS, PUST, DETLEV, A., W.
Applicants: KRITIS PLASTIKA, PUST DETLEV A W, PLASTIKA KRITIS S.A., PUST, DETLEV, A., W.
Application year: 1990
Main classification: A01G25
IPC codes: A01G25, B01D35