IL97577A - Flexible pipe for drip irrigation provided with integrated emitters - Google Patents

Description

097577/2 9 1 0 2 "FLEXIBLE PIPE FOR DRIP IRRIGATION PROVIDED WITH INTEGRATED EMITTERS" - ixnn t|ioa*O*i r >p»ni> vn THE APPLICANTS: 1. DAVID KARMELI »¾n:> in .1 YALDEI TEHERAN ST. ,21*1ilD ΊΊ Ί mm DANYA, HAIFA. . ,ΪΡ.Ι*Ι 2. GIDEON PERI *<13 nyu .2 15, MIVTZA YONATAN ST. 15 i-i3i*» yum mm HAIFA .no*Ti FLEXIBLE PIPE FOR DRIP IRRIGATION PROVIDED WITH INTEGRATED EMITTERS.

BACKGROUND OF THE INVENTION The invention relates to a pipe for drip irrigation which includes a plurality of emitter units heat bonded into the pipe at preferably even intervals. It is characterized by the possibility to increase the discharge of each unit separately relative to the size of the plant to be irrigated, and by the possibility to replace a clogged flow path by another flow path incorporated in the same emitter unit.

It need not be said that nowadays trickle or drt irrigation is becoming imperative and has to replace irrigation by sprinklers or channels, owing to the increasing scarcity of natural water resources and increased use of land for agriculture to feed the ever-increasing populations.

There exist many kinds of drip irrigation emitters which are designed for controlled constant discharge at different line pressures, the discharge control being, in most embodiments, effected by a flexible wafer or tongue which is urged into a flow restricting passage by pressure differential between line pressure and ambient pressure. Not only are the units relatively expensive owing to high manufacturing costs, but they are relatively sensitive to malfuctioning due to clogging and to deterioration of the flexible material. This usually means exchanging of an entire irrigation pipe, if several units are out of action, in order to prevent non-irrigation of a certain number of plants.

Today's trend is to provide drip irrigation pipes with a smooth outside which permit their ready laying and dragging over the ground, an aim not attainable with pipes having emitter units fastened to their outside, most constant discharge units are voluminous, ©ndj they generally protrude either wholly or partly out of the pipe, which evidently aggravates the aforementioned ^ operations. On the other hand, if controlled-discharge units are inserted into the pipe itself, they diminish the pipe's cross section owing to their large size and constitute a considerable flow resistance.

The drip irrigation emitters according to the present invention are not self-regulating and are apt to emit a larger discharge volume with increased line pressure. However, by installing pressure regulators at the head of a group of discharge lines it has become possible to control the line pressure to a high degree of accuracy, which makes the use of non-compensating drip irrigation emitters satisfactory, and would allow the use of emitters with flow rate variations within an acceptable range.

In view of the drawbacks of the known kinds of drip irrigation pipes it is the object of the present invention to provide a pipe with drip irrigation emitters of small annular cross section attached to the inside of the pipe wall with the object of presenting a minimum flow resistance within the pipe.

It is another object to provide each emitter with several separate flow passages of which only a part will be in use, for the purpose of permitting the use of the other pasages in case the first ones are clogged; or, in case a larger discharge volume should be required for a growing plant, of multiplying the throughflow.

It is still another object to provide an emitter unit of simple design, consisting of only one component which can be produced at low cost, thereby reducing the total expenses incurred in drip irrigation.

And it is a final object to provide emitters suitable for ready insertion into a flexible pipe during the process of its extrusion.

SUMMARY OF THE INVENTION The drip irrigation pipe according to the invention includes a plurality of one-piece in-line drip irrigation emitters disposed at predetermined spaced intervals and heat bonded to its wall inside. Each emitter is of cylindrical or part-cylindrical shape and has a smooth interior surface and an exterior surface containing at least two separate, independent flow restricting passages formed between the exterior surface of the emitter and the pipe wall and extending parallel to the cylinder axis in to and fro direction. The emitter is of a length large compared with its outer diameter which is coextensive with the diameter of the pipe in which it is disposed. The front end of each flow passage communicates with the pipe interior through several small openings extending through the emitter material, while the rear end opens into a discharge chamber, the latter communicating with the atmosphere through one or more openings in the pipe wall.

In a preferred embodiment each flow restricting passage is composed of at least two stretches extending in parallel alignment on the exterior surface of the emitter in the shape of a labyrinth of crosswise extending ribs or protrusions which cause the flow within these stretches to perform bows and bends through a tortuous or meandering path.

The different flow passages in one emitter may be in the same or in opposite direction, i.e. both inlet openings may be at one end of the emitter and the discharge chambers at the other end, or the discharge chambers and inlet openings may be located at opposite ends of the emitter unit.

Water will enter the flow passage through the small openings at the front end of the passage, which are destined to serve as filter, the line pressure will be reduced by flow resistance of the labyrinthine path, water will then enter the discharge chamber at reduced pressure and will be discharged from there to the atmosphere through one or more openings in the pipe wall. It is understood that initially only a part of the flow passages will be connected to the outside through holes or openings in the pipe wall, and that additional flow restricting passages will be connected to the open as soon as the first ones have become non-operative by clogging or that a larger throughflow is required due to the growth of the irrigated plant. Providing another opening is effected by cuttiing or punching a hole in the pipe wall at the location of the other discharge chamber of the emitter, which may be marked by a depression or any other marking.

The emitter is advantageously in the shape of a whole cylinder, having several flow paths impressed on its exterior surface, this shape being advantageous with regard to insertion of emitters into a pipe during its extrusion process. On the other hand, a part-cylindrical emitter has the advantage of presenting less flow resistance along the pipe, while lowering the manu- facturing costs due to simple dies and a simplified injection moulding process. The part-cylindrical emitter will usually have two separate flow restricting pasages, while the outer surface of the cylindrical emitter may be impressed with up to four separate passages.

A solution for manufacturing at relatively low cost is the assembly of a cylindrical emittter from two semi-cylindrical emitters, which will facilitate insertion and heat bonding to the inside of the pipe and permit the provision of up to four flow restricting passages It is reiterated that the trickle emitters of the present invention are not pressure compensating, but require standard pressure regulating system at the head of each irrigation area. It can also be shown that a limited permitted pressure drop along the pipe provided with this type of emitters can be achieved, by chosing a suitable pipe length, and owing to the reduction in the water volume downstream of every emitter and owing to the slow flow in a drip irrigation pipe, even of relatively great length.

SHORT DESCRIPTION OF THE DRAWINGS Figure 1 is a plan view - and part section - of a cylindrical drip irrigation emitter placed inside a flexible pipe, Figure 2 is a longitudinal section of the emitter of Figure 1 along the line A-A, Figure 3 is a cross section of the emitter of Figure 1 along the line B-B, Figure 4 is a cross section of the emitter of Figure 1 along the line C-C, Figure 2 is a longitudinal section of the emitter of Figure 1 along the line A-A, Figure 3 is a cross section of the emitter of Figure 1 alcng the line B-B, Figure 4 is a cross section of the emitter of Figure 1 along the line C-C, Figure 5 is a plan view of a part-cylindrical drip irrigation emitter provided with two flow restricting passages , Figure 6 is a section of the emitter of Figure 5 along line D-D, Figure 7 is a section of the emitter of Figure 5 along line F-F, Figure 8 is as section of the emitter of Figure 5 along line E-E, Figure 9 is a longitudinal section through a cylindrical emitter composed of two part-cylindrical emitters , and Figure 10 is a section of the emitter of Figure 9 along the 1 ine G-G .

DETAILED DESCRIPTION OF THE DRAWINGS Referring now to Figures 1 through 4 of the drawings a cylindrical emitter I is positioned in, and heat-bonded to, a pipe II, both the pipe and the emitter being of a plastic material suitable for fusing into each other. It is important that fusion is over the entire surface of the emitter, in order to prevent leakage between the several flow passages and to ensure that the entire water flow passes through the passage and not direct between inlet and outlet. The interior surface of the emitter is smooth, while the exterior surface is impressed with two U-shaped flow passages 1 and 1 'positioned on opposite sides of the cylinder, and in opposite direction of flow. Each flow passage is formed by intermittent teeth or protrusions 10 which extend into bays 11 and thus form a labyrinthine, tortuous passage. In the present embodiment the passage visible in Figure 1 is formed by two parallel stretches 11 disconnected at their one end by a bend 13, while their other ends communicate with an inlet chamber 14 and with a circumferential discharge chamber 15, both chambers being on the same side, i.e. on the left of the drawing in respect of the visible flow passage. The flow passage on the opposite side of the cylinder has both its inlet chamber 14' and discharge chamber 15' on the rright side of the drawing as indicated in Figure 2, for the reason that this arrangement permits provision of two circumferential discharge chambers. The discharge chamber 15 shown on the left communicates with the open by a perforation 16 in the pipe wall, while the right-hand discharge chamber 15' is still blocked, a possible later opening being marked by a minute depression 17 on the outside of the pipe. The drawings show that the discharge chambers circumvent the entire cylinder surface permitting the provision of an opening -such as 16 - in any place of the pipe, opposite the discharge chambers. The inlets to both independent flow restricting passages are in the shape of two rows of perforations 18 and 18\ extending from the inlet chambers 14 and 14' into the pipe interior. These perforations are of small cross section, so as to serve as filters holding back sediments and other pollution in the water and preventing their entry into the emitter. The portion of the outer surface not occupied by the flow passages is provided with circumferential ribs 19 as well as with a central groove 20 positioned between the two stretches of the flow passages.

Figures 5 through 8 illustrate a part-cylindrical emitter III provided with two pairs of independent, separate flow passages 101 and 101 · which are similar to the flow passages 1.1· illustrated in Figure 1. Both passages start from inlet chambers 14 and 14·, and terminate in discharge chambers 15 and 15', respectively. Water enters the emitter from the pipe through narrow openings 18 extending from the inlet chamber into the pipe interior, and leaves the emitter into the open from the discharge chamber though a hole 16 in the pipe wall.

Although insertion of the part-cylindrical emitter into the pipe and heat-bonding to its wall is slightly more difficult than in the case of the cylindrical emitter, it has the advantage of ready manufacture in simple dies. Combination of the advantages of both the cylindrical and of the part-cylindrical emitter, i.e. simple manufacture and ready insertion into the pipe is shown in Figures 9 and 10. Herein two part-cylindrical emitters 21 and 21' are jointed by two intermittent part-cylindrical portions 22 into a cylindrical emitter to be inserted into a pipe II. Again, as in the afore described embodiments, only one emitter (21) is in use and discharges water to the plant through an opening 16 in the pipe wall. Should this emitter be clogged, or does the plant require more water, after growth, a similar opening can be made in the pipe wall opposite the discharge chamber of the second part-cylindrical emitter 21'.

In order to accommodate long stretches of the flow restricting passages the emiiter units are relatively long, and for effective operation the minimum ratio of length to diameter is 3 to 1, which may be increased to 5 to 1 or even more.

It is evident and known that most components of the three embodiments of the emitter have been uti 1 ized in the past, but that the provision of at least two independent, separate flow restricting passages is novel, as well as the formation of one cylindrical emitter from two part-cylindrical emitters. Most of all, the cheap method of production of the emitters make the irrigation pipes readily available to any farmer, where they must replace the hitherto used wasteful irrigation by sprinklers. This does not only apply to Israel, but to most countries in semi-tropical countries where natural water sources are becoming scarce.

It will be understood that the trickle irrigation pipe and emitters illustrated and described in the foregoing represent only some examples of the many possible embodiments, and that many variations and modifications may be carried out to the emitters and to their arrangement within the irrigation pipe.

It is, for instance, proposed to have more than two flow restricting stretches in each passage. Instead of providing both the inlet and outlet chamber of each passage at one end of the unit, these may be located at opposite ends.

It is also proposed to convert the emitter into a controlled^discharge emitter by placing a pressure sensitive element into the discharge chamber, capable of graduallyt obstructing the outlet opening in the pipe as a result of increased pressure differential between the line and the outlet pressure.

Claims (10)

10 097577/4

1. C L A I M S :- 1. A drip irrigation pipe includes a plurality of one-piece in-line emitters disposed on its inside wall at predetermined spaced intervals, wherein each said in-line emitter is of cylindrical shape and has a smooth interior surface and an exterior surface containing at least two separate, independent flow restricting passages formed between said exterior surface of said emitter and the wall of said pipe and extending parallel to the emitter axis in to and fro direction, and wherein each said flow passage has a front end defining its inlet communicating with the interior of said pipe through several small openings, and a rear end in the form of a discharge chamber communicating with the atmosphere through at least one opening in said pipe wall, and wherein said front inlet ends of said separate flow passages are positioned alternately upstream and downstream inside said drip irrigation pipe.

2. A drip irrigation pipe includes a plurality of one-piece in-line emitters disposed on its inside wall at predetermined spaced intervals, wherein each said in-line emitter is of part-cylindrical shape and has a smooth interior surface and an exterior surface containing at least two separate, independent flow restricting passages formed between said exterior surface of said emitter and the wall of said pipe and extending parallel to the emitter axis in to and fro direction, and wherein each said flow passage has a front end defining its inlet communicating with the interior of said pipe - 11 - 097577/4 through several small openings, and a rear end in the form of a discharge chamber communicating with the atmosphere through at least one opening in said pipe wall, and wherein said front inlet ends of said separate flow passages are positioned alternately upstream and downstream inside said drip irrigation pipe.

3. The drip irrigation emitter as defined in Claim 1 or 2, wherein each said flow restricting passage is formed by two stretches connected at one of their ends by a bend, and wherein the other end of the first stretch is connected to an inlet chamber which communicates with said pipe interior by means of several small openings, and wherein the other end of the second stretch is connected to said discharge chamber, said inlet chamber and said discharge chamber being positioned at the same end of said emitter and upstream and downstream in alternating flow restricting passages.

4. The drip irrigation emitter as defined in Claim 1 or 2, wherein each stretch of said flow restricting passage is formed by intermittent protrusions along one side which extend into bays provided on the other side.

5. The drip irrigation emitter as defined in Claim 3, provided with two flow restricting passages, wherein said inlet chamber and said discharge chamber of each passage are positioned at opposite ends of said emittter, the inlet chamber of one passage being positioned adjoining the discharge chamber of the other passage.

6. The cylindrical drip irrigation emitter as defined in Claim 3, wherein said discharge chamber of each said flow restricting passage surrounds the entire circumference of said cylindrical emitter at each end.

7. The drip irrigation pipe as defined in any of the preceding Claims, wherein the length of each emitter is large compared with its diameter.

8. The drip irrigation emitter as defined in Claim 7, wherein the length of each emitter is between three and five times its diameter.

9. The drip irrigation pipe as defined in Claim 2, wherein a cylindrical emitter is formed from two part- cylindrical emitters jointed into cylindrical shape by means of two intermittent part-cylindrical portions positioned between said two part-cylindrical emitters.

10. The drip irrigation pipe as defined in one of Claims 1 through 7 and as hereinbefore described and illustrated in the accompanying drawings. FOR THE APPLICANTS,