IL106608A - Trickle irrigation emitter with by-pass - Google Patents

Description

"TRICKLE IRRIGATION EMITTER WITH BY-PASS" ΦΗΒ APPLICANT: DR. GIDEON PERI 15, MIV ZA YONATAN ST. nii> y^3D aim HAIFA. .n a » n All trickle irrigation emitters include one - or more -flow-restricting passage or flow-path and a discharge chamber at the downstream end of the passage; an inlet connects the passage with the pipe interior, and the discharge chamber communicates with the outside through a suitable opening. The full line pressure at the upstream end of the passage is reduced by the flow resistance in the passage and reaches the discharge chamber at the required low pressure to ensure trickle discharge. To compensate for varying line pressures and to ensure that the discharge be more or less identical, independent of these variations, means are provided serving to reduce the cross section of the passage with increasing line pressure. The so-called self-compensating units include a base having a flat surface impressed with the passage - or flow-path - and the discharge chamber which are covered by a loosely movable, relatively thin, flexible sheet, a so-called membrane, the opposite surface of which is exposed to the full line pressure. With increasing line pressure the membrane is urged onto the base and partly pressed into the flow path and the discharge chamber causing their cross sections to be reduced and the flow resistance to be Increased. Dependent on the shape of the flow path and the properties of the membrane the cross section of the flow path and the discharge chamber varies according to the line pressure resulting in a more or less equal trickle discharge independent of the pressure in the pipe.

One major drawback of all trickle irrigation emitters is clogging by dirt or sediments of their flow path which will often necessitate replacement of the entire length of pipe, since a number of plants in the row are not being sufficiently irrigated. The remedy of increasing the line pressure and flushing the flow path - used with non-compensated emitters - is usually not effective with the self-compensating kind, owing to the fact that the increased pressure on the membrane closes the flow path and the discharge chamber still more than before and keeps the dirt in place.

It is, therefore, a foremost object of the present invention to provide a self-compensating emitter which will continue to discharge water to plants, even after clogging, though at a slightly reduced rate It is another object of the invention to provide a trickle irrigation emitter which is less sensitive to clogging and which will lend itself to ready flushing of an obstruction It is another object to provide a self-compemsating emitter of improved performance while retaining its external shape, at no additional cost.

The improvement can be carried out to emitters both attached to the outside of an irrigation pipe as well as to emitters integrated with the inside of the pipe or hose.

SUMMARY OF THE INVENTION.

The improvement to a self-compensating emitter comprises the addition of a by-pass in the form of a short, shallow duct starting from the inlet of the labyrinthine flow path to the discharge chamber. The cross section of the by-pass should not exceed .25% of the cross section of the main flow path, causing 60-90% of the flow to pass through the main path, while the remaining 10-40% would go through the by-pass. Since the membrane covers both the main flow path and the by-pass, increased line pressure will urge the membrane into both passages and reduce their cross section; this will increase their flow resistance to a similar degree and effect a compensating action more or less like in an emitter without a by-pass. However, the chance of the by-pass being clogged is very slim owing to its short straight length, whereas the labyrinth is more readily clogged. Removal of a clogging in the flow path by increased line pressure is made possible for the following reason:- The discharge chamber and the part of the flow path beyond the obstruction are at full line pressure by their connection to the inlet through the by-pass; this leaves the membrane more or less free floating above the labyrinth and permits the increased water pressure to clear the obstruction. On the other hand, should the clogging not be removed and the flow path remain closed, then the emitter would still be operative due to water flow through the by-pass, although at a slightly reduced rate. This fact will, of course, allow the irrigation pipe to remain in situ instead of having it replaced by a new pipe with clean emitters. In all cases where the inlet and the discharge chamber are at opposite ends of an emitter, a large duct should be provided parallel to the flow path, of a size not apt to reduce the flow there- - 4 - 106,608/2 through, with the by-pass extending from its end into the discharge chamber^.

In addition to the by-pass connecting the inlet with the discharge chamber, it is proposed to provide one or more by-passes communicating certain sections of the flow path direct with the pipe interior. Again, as with the above by-pass, these should be short, straight ducts of small cross section compared with the cross section of the main flow path, having the purpose of facilitating flushing of the clogged labyrinth. It is evident that such an additional by-pass will result in full line pressure beyond the obstruction, lifting the membrane and allow clearing of the sediments or dirt out of the emitter.

It is reiterated that a by-pass - or additional by-passes - can be provided on any self-compensating emitter, be it attached to the inside or the outside of an irrigation pipe, and irrespective of the shape and length of the flow restricting passage.

BRIEF DESCRIPTION OF THE DRAWINGS.

Figure 1 is a a cross section of a trickle irrigation pipe and an emitter attached to its inside wall, Figure 2 is a section along line 2-2 of Figure 1, showing the shape of the flow path,, the discharge chamber and a by-pass, Figure 3 is a section along line 3-3 of Figure 2, Figure 4 is a cross section along line 4-4 of Figure 5 showing a second embodiment of an emitter attached to its inside wal 1 , Figure 5 is a section along line 5-5 of Figure 4, showing the shape of the flow path, of the discharge chamber and of two by-passes, Figure 6 is a section along line 6-6 of Figure 5, Figure 7 is a section of a cylindrical trickle irrigation emitter usually attached to the outside of an, irrigation pipe, and Figure 8 is a modification of the cyl indrical emitter of Figurre 7. " ) ' DETAILED DESCRIPTION OF THE DRAWINGS. \ Figures 1, 2 and 3 illustrate a first embodiment of an emitter attached to the inside of an irrigation pipe 1, usually by heat welding during extrusion of the pipe. The emitter includes a rectangular casing 2 which is divided by a partition 3 into a membrane housing 4 and an outlet pool 5. In a manner known to the art a flow-restricting passage 6 and a discharge chamber 7 are impressed into the smooth surface of the partition, a water inlet 8 connecting the passage with the pipe interior, while an outlet bore 9 penetrates the partition and connects the discharge chamber with the outlet pool 5. An outlet opening 10 in the form of a punched hole through the pipe X permits water to reach the outside. The entire partition is covered by a flexible, thin membrane 13 which is urged onto and into the impressed portions by the line pressure acting on its outside. Up to here the emitter is of the conventional kind, wherein the inlet and outlet are at opposite ends of the casing. As said before, the invention includes the provision of a short and straight by-pass between the inlet? and the discharge chamber/^ overcoming ends, which would require a long, unsuitable by-pass, a short by-pass 11 is placed between the discharge chamber?, and the end of a long duct 12, the latter extending from the inlet 8 towards the discharge chamber 7 stopping short off the chamber.

In case the labyrinth 6 is clogged by an obstruction, by-pass 11 will supply a reduced water flow through the emitter, since neither the duct 12 nor the by-pass are apt to be clogged, not to mention the wide discharge chamber?. On the other hand, flushing of the obstruction is made possible, owing to the fact that the line pressure acts on both sides of the membrane along duct 12 and over the discharge chamber which communicates with the inlet via the by-pass. This will lift the membrane off the labyrinth and increased line pressure is apt to flush the obstruction out of the emitter.

A second embodiment of a trickle irrigation emitter is illustrated x in Figures 4, 5 and 6. It differs from the aforedescribed embodiment mainly by the shape of the flow path 6' which is in U-shape, i.e. it is composed of two parallel branches interconnected at their one end, while their other ends communicate with the inlet 8 and the discharge chamber 7 respectively. The casing and all other features of the emitter are identical with that of the first embodiment and are designated by identical numerals. The difference expresses itself by the provision of two by-passes - instead of one - and their position in relation to the U-shaped flow path. They include a first straight and short by-pass 11 connecting the closely positioned inlet and discharge chamber, and a second, somewhat longer, by-pass 15 which connects one flow path branch with the pipe interior, while extending through the casing wall. It will be understood that the location of this second by-pass is being shown in a arbitrary manner, and that it may be located at any distance from the discharge chamber. In certain cases more than two by-passes may be provided.

In case of the path being clogged by an obstruction, both by-passes will serve as emergency flow-paths, and the emitter will continue to operate and to irrigate the plants around it. They will also assist in flushing the obstruction by means of increased line pressure, since they will tend to raise the membrane off the flow path th reb the obstruction will be able to free itself.

The emitter illustrated in Figure 7 is of the conventional type to be inserted into a pipe from the outside by means of a perforated plug. It has a cylindrical casing 25 enclosing a substantially circular flow path 20. An inlet 22 enters the flow path through the casing and a central outlet 23 surrounded by a discharge chamber 24 defines the downstream end of the path. The invention is defined by a straight and short by-pass 21 of small cross section connecting the inlet with the discharge chamber. A second, optional by-pass 26 is shown to connect the central portion of the circular flow path with the pipe interior.

The emitter illustrated in Figure 8 is similar to that of Figure 7, but shows a circular channel 27 surrounding the flow path in spaced-apart relationship, with the aim to providing communication of the inlet with the optional second by-pass 26. In all other respects the two cylindrical emitters are identical and their operation in case of clogging is similar to that described in respect to the internal emitters.

The cross section of the by-pass should not exceed 25% of the cross section of the flow path. It should be as short, as possible and extend in a straight line so as to present a minimum of flow resistance, while its section may have any form suitable for manufacture. Under free and unobstructed flow the by-pass should be designed to permit a throughflow of from 10 to 40% of the entire discharge, the remainder to go through the labyrintine flow path. After clogging the by-pass may deliver up to the full nominal flow through its entire cross sectional area, there existing no restriction by pressure of the membrane.

The addition of one or more by-passes will greatly improve irrigation control, even with non-compensating emitters which otherwise would have a discharge proportional to the line pressure.

It will be understood that the by-pass and the second optional by-pass may be provided in any trickle irrigation emitter, irrespective of its design and shape, and that the invention is not restrcited to the emitters illustrated and described in the foregoing..

Claims (9)

C L A

1. , An improved self-compensating trickle irrigation outsi e, a thin flexible membrane having a first surface in close contact with said flow restricting passage and said discharge chamber and having its second opposite syf ce exposed to the full water pressure in said pipe, serving to increase the flow resistance in said passage with increasing water pressure, the improvement .iif; ovision of a short and substantially straight by-p&ss *t connecting said water inlet with said discharge cham er, 50: id by-pass being impressed in said base and , eing covered b said membran .

2. , The trickle irrigation emi ter of Ciaim 1, wh rein the cross sectional area of said by-pass is less or equal 25% of the cross-'- sectional area of said flow restricting passage.

3. , T ii improved trickle irrigation emitter of Claim 1. including the prevision of at least one additional by- pa s covered by said membrane and connecting a point of said flow restricting passage with the interior of said - 10 - 106,608/2

4. The improved trickle irrigation emitte of Claim 1, of the kind having a U-shaped flow restricting passage including two sections extending parallel to the axis of said emitter, wherein said water inlet and said discharge chamber are positioned at one end of said emitter and are connected by a by-pass extending perpendicular to the longitudinal axis of said emitter.

5. The improved trickle irrigation emitter of Claim 1, of the kind having a straight flow restricting passage parallel to its longitudinal axis with said water inlet at one end of said emitter and said discharge chamber at its other end, the improvement of providing a wide duct extending from said water inlet to close to said discharge chamber and providing said by-pass from the end of said duct to said discharge chamber, for the purpose of providing a short by-pass..

6. The improved trickle irrigation emitter of Claim 1, of the kind having a cylindrical housing and a substantially circular flow passage with a lateral water inlet communicating with the inlet end of said circular passage and with a discharge chamber in the center of said housing, wherein said by-pass extends from said passage in the vicinity of said inlet to said discharge chamber in radial direction.

7. The improved trickle irrigation emitter of Claim 1, of the kind having a cyindrical housing and a substantially circular flow passage with a lateral water inlet communicating with the inlet end of said circular passage and with a discharge chamber in the center of said housing, 11 106,608/2 wherein a circular channel surrounds said flow passage in spaced relation and communicates with said water inlet, and wherein a first by-pass extends from said passage in the vicinity of said inlet to said discharge chamber, and wherein a second by-pass extends from said channel to said flow passage.

8. The improved trickle irrigation emitter of 4, 5 or 6, wherein one or more additional by-passes are provided extending from one or more points along said flow restricting passage to the interior of said pipe.

9. The improved trickle irrigation! emitter as defined by any of the Claims 1 through 8, and substantially as herein before described and illustrated in the accompanying drawings. FOR THE APPLICANT, E.A. GLUCKSMAN, PATENT ATTORNEY.