A SYSTEM FOR DRIP IRRIGATION AND A DRIP NOZZLE

Abstract: The drip nozzles (1) of the system for drip irrigation of plants comprise a nozzle member (2) with a feeding channel (11, 12, 13) and an outlet channel (15, 17, 18, 26). The outlet (14) of the feeding channel and the inlet (16) of the outlet channel in the nozzle member (2) are covered by a resilient membrane (3). In connection with a low water pressure, the latter membrane closes both the outlet and the inlet (14, 16), and in connection with a high water pressure it opens the passage between the outlet and the inlet. The drip nozzle according to the invention prevents air from entering said nozzle to a substantial degree, and accordingly prevents deposits of calcium and ferric oxide from blocking up the interior of the nozzle in such a manner that the functioning period of the nozzle is very long.

Description: Title: A System for Drip Irrigation and a Drip Nozzle Technical Field The present invention relates to a system for drip irriga¬ tion of the type stated in the preamble of claim 1 and a drip nozzle of the type stated in the preamble of claim 2. Background Art Various drip tubes and nozzles are used in irrigation systems, where the water is supplied to for instance plants through feeding pipes and thin water pipes. Such systems are characterised by the irrigation water being slowly, such as drippingly, supplied to the nursery bed in such a manner that the water is oxidized and a slow seepage down to the roots of the plants is taking place. Most systems for drip irrigation are based on low pressure, such as for instance a column of water of 1 to 1.8 m, in order to achieve the aforesaid effect. A simultaneous irrigation of large areas by way of the above low pressure necessi¬ tates rather large supply pipes and tubes. When drip tubes are used, said tubes are of a diameter of about 1 to 2 mm, in which calcareous deposits set in from the open end with the result that said end must be cut-off in order to re-open the outlet or with the result that the drip tube is generally replaced by a new tube being placed on the supply tube. The known drip nozzles are provided wi-th a complicated channel system reducing the water pressure in order to adjust the flow of water to the desired low speed. When the supply of water is interrupted periodically, the water is sucked especially from the top drip nozzles into the supply tube with the result that a water membrane remains , said water membrane being oxidized by the entrance of atmospheric air while forming hard deposits of calcium and ferric oxide. When fertilizers have been admixed the water, the drip nozzles may furthermore be choked due to crystallization with the result that the nozzles are quickly blocked up and cannot be used. When the drip nozzles are used in a system placed on an undulating ground whether in a greenhouse or outdoors, the plants growing in the low areas are supplied with too much water through functioning drip nozzles with the result that the ground may turn sour, whereas the plants growing in the high areas are only supplied with little or no water at all due to the low pressure and the advanced blocking. Accord¬ ingly the latter plants are dried. Attempts have been made at using the known drip nozzles in systems involving high pressures with restraining zones with the result, however, that the deposits and impurities are compressed inside the nozzles so that they are very difficult and expensive to remove from the nozzles. As an example a cleaning out of the nozzles in a single greenhouse of 20 times 100 m may cost up to DKK 10,000. In addition, the production of the known drip nozzles is expensive due to their complicat¬ ed structure. '' Disclosure of the Invention The object of the present invention is to provide a system for drip irrigation and an inexpensive drip nozzle to be used in said system, which ensures a uniform and reliable irrigation of large cultivated areas both in greenhouses, plantations, nurseries and market gardens etc., where the drip nozzle must be able to operate with a high pressure inside the supply tube, and which in ordinary operation prevents atmospheric air from entering the channels of said drip nozzle, and which is not liable to get blocked up, and finally which is easy to clean out. The above object is provided by the system and the drip nozzle mentioned in the introduction to this specification, said system and said drip nozzle being characterised by the subject matter of the characterising clause of claim 1 and 2, respectively. The resilient closing means ensures an automatic closing by closing for the water, i.e. in case of a low water pressure, and by closing the outlet and the inlet, whereby a back flow is prevented and a small column of water remains in the outlet channel. As a result, calcium and ferric oxide are subs antially com¬ pletely prevented from depositing inside the feeding and outlet channels as well as in the supply tubes. At the same time it is possible to involve pressures exceeding a 30 m column of water and accordingly it is possible to use longer and/or thinner supply tubes and feeding pipes than previously, the latter presenting a great advantage in connection with growing plants outdoors. The use of a high water pressure and the securing against an emptying at the closing means or the membrane ensure furthermore that all plants are supplied simultaneously with substan¬ tially the same amount of water irrespective of the con- figuration of the ground. Previously, the irrigation sometimes started at the plants growing adjacent the supply source, and not until later the plants growing far from the supply source were irrigated. The drip nozzle according to the invention can be used in existing systems, option- ally by increasing the pressure in the water supply. The new systems are encumbered with the advantage that it is possible to use supply tubes and feeding pipes of a smaller diameter than previously, whereby the costs involved in using the drip nozzle according to the invention are additonally reduced. When the water supply is opened, each drip nozzle is immediately pressurized with the result that the membrane is pressed away from the outlet of the feeding pipe and the water is pressed while subjected to a high drop in pressure below the membrane towards the inlet of the outlet pipe so as thereby to flow through and drip from the outlet pipe at an adjusted speed. When the pressure is removed, the membrane closes both the outlet and the inlet, and a column of water remains in the outlet with a drop of water hanging at the bottom because the membrane closes the inlet of the outlet pipe. The column of water and the drop evaporate slowly in response to the moisture of the air and the surrounding heat, but simultaneously said column of water and said drop prevent, usually until the next irrigation period, air from entering the outlet pipe. The closing by the membrane of the outlet of the feeding pipe blocks up completely the feeding pipe for entrance of air. As a result, the depositing of calcium and ferric oxide is substantially delayed or completely prevented. Should the outlet pipe be blocked up either by "calcifica- tion" or by penetrating dirt, the latter can easily be removed by the membrane being pushed aside and by the outlet pipe being cleaned out by means of a wire or a corresponding scraping means. As the nozzle is inexpensive and easy to replace, it is often less expensive to replace said nozzle. .- The characterising clause of claim 3 deals with a parti¬ cular embodiment which is easy to manufacture. The charac¬ terising clauses of claims 3 to 7 deal with practical embodiments which are simple and inexpensive to manufacture by way of mass production. The embodiment dealt with in the characterising clause of claims 6 and 7 ensures a retaining of a large column of water and drop in such a manner that the evaporation and consequently the entrance of air into the outlet pipe is maximally. delayed so as to prevent "calcification". The embodiment dealt with in the characterising clause of claim 8 ensures that the passage opening between the axial and radial lengths of pipe is of a complete dimension. The membrane dealt with in the characterising clause of claim 9 is an inexpensive membrane, which is easy to replace with respect to maintenance at the same time as the column of water is extended so as to delay additionally the evaporation and the resulting depositing of calcium and ferric oxide. The circumferential recess described in the characterising clause of claim 10 ensures that the water does not flow in an uncontrolled manner outside the outlet channel and over the lower end and outlet opening of the nozzle member. The blocking bead described in the characterising clause of claim 11 ensures that the water does not seep in an uncontrolled manner downwards along the outer surface of the nozzle member, whereas the slot stated in the charac¬ terising clause of claim 12 ensures a limited irrigation of each plant in case the outlet channel gets blocked up by dirt. Brief Description of the Drawing The drip nozzle according to the invention is described below in three embodiments with reference to the accompa¬ nying drawing, in which Fig. 1 is an enlarged view of a first embodiment of the drip nozzle according to the invention, a sectional view of a valve tubing appearing as well, Fig. 2 is an enlarged view of a second embodiment of the drip nozzle according to the invention with a supply tube inserted and wherein the right half appears in section, Fig. 3 is a diagrammatic view of a system for drip irriga¬ tion, Fig. 4 illustrates an alternative embodiment of the drip nozzle corresponding to the nozzle of Fig. 1, but where said alternative embodiment has been supplemented with a circumferential recess in the surface of the nozzle oppo¬ site the inlet of the outlet channel thereof, and Fig. 5 is a sectional view of the drip nozzle of Fig. 4 taken along the line V-V. Best Mode for Carrying Out the Invention Corresponding parts have been designated the same reference numerals in the drawing, an "a" being added to the deviat¬ ing embodiments of Fig. 2. The references "upwards" and "downwards" and the like refer to the drawing, A drip nozzle 1, la. for irrigation of plants and according to the invention comprises a nozzle member 2, 2a. preferably made of hard plastics, and a resilient pressure means, i.e. a membrane/valve tubing 3 in the illustrated embodi- ments, said resilient pressure means closing tightly about the major portion of the circumference of the nozzle member. In use the nozzle member is connected to a supply tube 4. On the outside the nozzle member 2, 2a. comprises - at the top a top member 5 with a rest 6 for the membrane 3 at the bottom thereof, at a short distance (3 to 4 mm) below the rest a plurality of circumferential sharp*-edged membrane- holding beads 7, 8 and 7, 8, 9, respectively, and - at the bottom at least one circumferential blocking bead 10 of a circular cross section to prevent seeping of water along the outer surface at the bottom. The inlet channel of the nozzle comprises the outer end of the supply tube 4 inserted and clamped and retained by way of friction in a recess 11, said recess being conically and downwardly tapered with respect to varying diameters of the tubes and an easy introduction of the above end. The retaining can be further ensured by means of for instance glue or ruggings or clamping means , such as spring rings or screws (not shown) . The recess is terminated by a rest 19 for the supply tube, - an axially extending first length 12 of feeding pipe, and a radially extending second length 13 of feeding pipe with an outlet 14 in the outer surface of the nozzle member 2, 2a.. The outlet channel of the nozzle comprises a radially extending first length 15 .of outlet pipe with its inlet 16 positioned in the outer surface of the nozzle member 2, 2a. in axial distance downstream the outlet 14 and upstream the blocking bead 10, and optionally staggered in the circumferential direction, cf. Fig. 1, an axially extending second length 17 of outlet pipe, an axially extending third length 18, 18a. of outlet pipe of a larger diameter than the lengths 12 to 17 of pipe, and an extension 26 of the valve tubing 3 extending beyond the nozzle member 2, 2a.. Usually, the valve tubing 3 fits tightly to the outlet and the inlet 14 and 16, respectively, so as to close said outlet and inlet. Dimensional examples of the drip nozzle shown in the drawing are: Internal diameter of the lengths 12-17 of pipes about 0.5 to 3.0 mm, especially 1.5 mm; the length 18, 18a. of pipe and the extension 26 about 3.5 to 7 mm, especially 4.5 mm and 5 mm, respectively. The drip nozzle is of a length of about 25 to 50 mm, especially 30 to 40 mm, and especially 33 mm. Other dimensions, both larger and smaller, can be used. A shoulder 21 can be shaped in a particular, water-column- carrying manner at the transition between the second and the third length 17 and 18 of pipe, such as either by a sharp circumferential recess 21, cf. Fig. 1, or a rounded circumferential recess 21a., cf. Fig. 2 r and/or a water-binding coating, optionally also applied onto the inner surfaces of the second and the third length 17 and 18 of pipe and the extension 26 and/or the inner surfaces of the lengths 17 and 18 of pipe can be provided with a rugging or a corrugation. The axial lengths 12 and 17 of pipe have been extended in axial direction by a recess 23 and 24, respectively, past the radial lengths 13 and 15, respectively, of pipe in order to ensure a complete passage. The outer surface of the nozzle member may be provided with a circumferential recess 30, cf. Figs. 3 and 4, opposite and in flow connection with the outlet channel 15. In this manner it is ensured that the water leaving the outlet 14 is always directed to the length 15 of outlet pipe in such a manner that water can only seep over the rear end of the nozzle member when the outlet channel 15 , 16, 17, 18, 26, 30 has been blocked up. A narrow slot 25, cf. Fig. 2, may be cut in the blocking bead so as to provide for seepage of water in case the outlet channel is blocked up by for instance sand or clay. The flow resistance inside the slot 25 must, however, be substantially stronger than the one inside the outlet channel in order to prevent water from seeping out this way in an uncontrolled manner. The drip nozzle according to the invention operates in the following manner: A plurality of drip nozzles are connected through indivi¬ dual supply tubes 4 to a common pressure pipe 27, cf. Fig. 3, with a water pressure of for instance 30 m water column. When the water is turned on, said water is by virtue of the high water pressure caused to flow directly through the supply tubes 4 to each drip nozzle and conse¬ quently to each plant 28 irrespective of the' fact whether the system for drip irrigation has been placed on an 1 " un¬ dulating ground whether outdoors or in a greenhouse. The bendings and small diameter, such as 1 to 2.5 mm, of the inlet channel cause the water to flow therethrough under a decreasing pressure to the outlet 14, cf. Fig. 2. At the outlet the water presses the closing means or the membrane 3 away from the surface of the nozzle member 2 and fills a space 29, cf. Fig. 2, with water. The con¬ tinuously decreasing drop in pressure presses the water to the inlet 16 and further through the outlet channel while forming a column of water inside the channel sections 30, 15, 17, 18, 18a, 24 and 26. The blocking bead 10 ensures during the usual running of the system that the flow of water is not pressed in an uncontrolled manner downwards between the surface of the nozzle member 2 and the valve tubing 3 to the periphery of the outlet opening 20. Instead the water is forced into the inlet 16. During the latter flow, the pressure of the water has been de¬ creased sufficiently for said water dripping onto the ground at the plant 28 in question, cf. Fig. 3, at a controlled rate. Each system of drip irrigation allows an adjustment of the rate and the amount of water to various strains of plants by using drip nozzles having different intervals and different flow directions between the outlet 14 and the inlet 16, cf. Figs. 1 and 2, and/or by choosing drip nozzles where the inlet and outlet channels are of suitable diameters, cf. above. When the pressure pipe 27 is turned off, the pressure inside the drip nozzle 1 drops, and the connection between the outlet 14 and the inlet 16 is interrupted by the membrane retighening both said outlet and said inlet by virtue of its resilience. In this manner it is primarily ensured that the column of water inside the outlet channel and the following air are not resucked into the sup-ply tube 4 in connection with the drop in pressure therein. Accordingly, calcium and/or ferric oxide cannot deposit therein at all. Secondly, the column of water inside the outlet channel remains therein with a drop hanging down¬ wards due to the particular shape of said outlet channel, whereby atmospheric air is immediately prevented from coming into contact with large water surfaces inside the outlet channel. As a result, the column of water is only insignificantly oxidized. In practice deposits of calcium and ferric oxide inside the outlet channel of the drip nozzle are almost completely avoided, and to a 99% degree inside greenhouses having a high relative humidity. When the drip nozzle is not used for a long time, it is not possible, especially in a very dry climate, to avoid evaporation of water from the column of water, but under all circumstances the deposits of calcium and ferric oxide are substantially reduced compared to the deposits appear¬ ing in connection with the conventional types of drip nozzles. The large diameter of the third length 18, 18a. of outlet pipe and of the valve tubing 3 ensures further- more that the area in question subjected to most deposits of calcium and ferric oxide can receive a high amount of deposit products before it is completely blocked up. Even after such a blocking up of the outlet channel, the greater resilience of the valve tubing compared to that of ordinary drip tubes implies that the extension 26 thereof functions as an additional safety valve which yields to an increased water pressure and ensures a seepage of water along the surface of the nozzle member past the blocking of the outlet channel. Accordingly, the plant in question is secured against a drying out. Such a seepage occurs, however, in a more uncontrolled manner and may optionally imply that the site in ' question is watered too much. As stated above, the known drip nozzles operate at a relatively low pressure, such as 1.8 m to 3 m of water column, in such a manner that plants growing far from 'the supply source, especially in an undulating ground, are watered less or even not at all compared to plants growing close to the supply source. Theoretically speaking it is also possible completely to omit the first, the second and the third length 15, 17 and 18 of outlet pipe in such a manner that the water is pressed out directly between the nozzle member and the valve tubing through one or more slots 25 which then are somewhat wider than stated above. Such a procedure in- volves, however, a high risk of deposits of calcium and ferric oxide and furthermore an uncontrolled irrigation of the plants, the reason why it does not present a pre¬ ferred embodiment. The drip nozzle 1 according to the invention is particular- ly used for irrigation of individual plants 28 growing in greenhouses, market gardens, nursery beds, plantations and corresponding growing sites, such as in fields growing particular crops .

Claims: Claims 1. A system for drip irrigation and comprising a plurali¬ ty of supply tubes and drip nozzles connected to said supply tubes as dosing nozzles, c h a r a c t e r i s e d in that each drip nozzle (1, la.) comprises a) a nozzle member (2) having a first nozzle chamber fluid- tightly connected to the supply tube (4) , and a second nozzle chamber physically separated from said first cham¬ ber, and b) a resilient closing means closing in a first position any fluid passage between the first and the second nozzle chamber, and which allows liquid to pass from the first to the second nozzle chamber and further to the opening of the latter when pressurized liquid is present in the supply tube (4) and consequently in the first nozzle chamber . 2. A drip nozzle for drip irrigation, especially of plants within the gardening and plantation industry, including greenhouses and nurseries, and comprising a nozzle member with feeding and outlet channels, c h a r¬ a c t e r i s e d in that the outlet (14) of the feeding channel and the inlet (16) of the outlet channel in the nozzle member are covered by a resilient closing means, such as a membrane (3) , which closes the passage between the outlet and the inlet and closes the outlet and inlet, respectively, (14 and 16, respectively) when the water pressure is low, and which opens said passage between the inlet and the outlet when said water pressure is high. 3. A drip nozzle as claimed in claim 2, c h a r a c - t e r i s e d in that in mutual downstream sequence the feeding channel comprises a first axial length (12) of feeding pipe and a second substantially radial length (13) of feeding pipe in open connection with said first length (12) of feeding pipβj that the feeding channel comprises an outlet (14) in the outer surface of the nozzle member (2) , and that downstream the outlet (14) the outlet channel comprises in mutual downstream sequence an inlet (16) in the same outer surface of the nozzle member (2) and at least one first substantially radial length (15) of outlet pipe and a second axial length (17) of outlet pipe in open connection with said first length (15) of outlet pipe. 4. A drip nozzle as claimed in claim 3, c h a r a c - t e r i s e d in that an axial recess (11) in the nozzle member (2) for receiving the supply tube (4) communicates openly with the first axial length (12) of feeding pipe, and that said recess (11) preferably is conically tapered towards the first axial length (12) of feeding pipe for receiving and retaining of said supply tube. 5. A drip nozzle as claimed in claim 4, c h a r a c ¬ t e r i s e d in that the inner surface of the recess (11) is rugged or coated with a binding material for retaining the supply tube (4) , or that clamping means are provided for clamping said supply tube in its posi¬ tion. 6. A drip nozzle as claimed in one or more of the claims 3 to 5, c h a r a c t e r i s e d in that a third axial length (18) of outlet pipe communicates openly with the second axial length (17) of outlet pipe downstream said second length and comprises the outlet opening (20) of the nozzle member (2), said third axial length (18) being of a diameter exceeding the diameter of said second axial length (17) of outlet pipe. 7. A drip nozzle as claimed in claim 6, c h a r a c ¬ t e r i s e d in that the transition between the second and the third length (17 and 18, 18a., respectively) of outlet pipe is shaped as a drop-retaining shoulder (21, 22, 22a.) , and that the inner surfaces of said lengths of outlet pipe preferably provide a water-binding coating and/or shape, such as a corrugation or rugging. 8. A drip nozzle as claimed in one or more of the claims 3 to 7, c h a r a c t e r i s e d in that the bores of the first and the second, respectively, axial length of feeding and outlet pipe (12 and 17, respectively) are extended in axial direction with recesses (23 and 24, respectively) past the radial lengths of feeding and outlet pipe (13 and .15, respectively). 9. A drip nozzle as claimed in one or more of the claims 2 to 8, c h a r a c t e r i s e d in that the closing means or the membrane is a valve tubing (3) retained in the distended position against the outer surface of the nozzle member (2) and further retained by means of a plurality of circumferential sharp-edged beads (7, 8 and 7, 8, 9, respectively) , said valve tubings covering both the outlet (14) of the feeding channel and the inlet (16) of the outlet channel and preferably protruding by an extension (26) past the outlet opening (20) of the nozzle member (2) . 10. A drip nozzle as claimed in one or more of the claims 2 to 8, c h a r a c t e r i s e d in that a circumferen¬ tial recess (30) is provided in the outer surface of the nozzle member (2), said recess allowing passage to the first length (15) of outlet pipe. 11. A drip nozzle as claimed in one or more of the claims 2 to 8, c h a r a c t e r i s e d in that on the outer surface of the nozzle member (2) a circumferential blocking bead (10) is provided downstream the inlet (16) of the outlet pipe. 12. A drip nozzle as claimed in claim 11, c h a r a c- t e r i s e d in that a narrow slot (25) is cut in the blocking bead (10) , said slot extending in axial direction. 13. A drip nozzle as claimed in one or more of the preced¬ ing claims , c h a r a c t e r i s e d in that the inter- nal diameters of the first, the second, and the third length (15, 17 and 18) of outlet pipe and of the valve tubing extension (26) are adjusted such that they can carry a column of water of subs antially the same height as the length from the bottom of the inner recess of the second length (17) of outlet pipe to the outlet opening of the valve tubing (3) plus a water drop hanging from the latter opening, and that the distance from the beads (8 and 9, respectively, and 10) to the outlet (14) and the inlet (16) is such that the membrane (3) in the non- pressurized state closes tightly to said outlet (14) and said inlet (16), and t at the distance has been adjusted by way of tests to the pressure inside the feeding pipe and the desired amount of drops.

Inventors: JENSEN NIELS THORKILD, JENSEN, NIELS, THORKILD
Applicants: DGT VOLMATIC AS, DGT-VOLMATIC A/S
Application year: 1989
Main classification: A01G25
IPC codes: A01G25