WEED AND TRASH SCREENING APPARATUS FOR IRRIGATION SYSTEMS

Abstract

The invention relates in general to weed and trash screening apparatus for irrigation systems. In one embodiment a debris screening apparatus is provided for use adjacent a check structure in a canal having a flow of water. The preferred apparatus comprises a frame substantially open to the flow of water and adapted to abut the check structure and a screen having at least one face with a plurality of pleats. The screen is mounted within the frame and, during operation, a first portion of the screen is submerged within the water, a second portion of the screen is above the water and a portion of water in the canal is directed through the screen. Screen face cleaning means are operable to periodically clean debris off of the screen's at least one face.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application is a regular application of U.S. Provisional Patent Application Ser. No. 61/470,463 filed Mar. 31, 2011 and entitled, “WEED AND TRASH SCREENING APPARATUS FOR IRRIGATION SYSTEMS”, the entirety of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to an apparatus for catching trash or debris from water and, more particularly, to a debris screening apparatus adapted for use in an irrigation ditch.

BACKGROUND OF THE INVENTION

During the passage of water down a stream or river, leaves, tree branches or other trash may float to be carried down the river or stream to enter an irrigation ditch. Irrigation ditches are also normally open and therefore may collect leaves, limbs, grass, weeds and the like during passage of the water. Moss, algae, aquatic weeds as well as leaves, stems and litter are therefore typically present in these open irrigation ditches. Such debris may be carried down to a point which would impede the flow through a diversion device, damage downstream pumps and clog or plug irrigation equipment, such as siphon tubes, gated pipes, and sprinklers. The need to allocate time and labour to address this problem, as well as the loss in water conveyance and down-time, presents a significant burden to both irrigation districts and water users. The removal of such debris is thus of importance.

One way to remove such debris is through the use of physical screening devices at canal inlet structures, weirs, canal check structures or the like. For example, stationary screens may be placed in-line across irrigation ditches at check structures, or at entrances to lateral canal branches, to catch the unwanted debris. A major advantage of removing debris in this manner is that it collects only once and nothing is sent downstream with the potential for further clogging, thereby reducing problems for downstream irrigators. This is a particular advantage in narrow canals that tend to collect debris across the entire downstream canal width. However, such stationary screens will need to be cleaned regularly, therefore requiring both manual labour and regular periodic surveillance of the screens.

Irrigation districts may also employ screening that removes debris using an automated, sweep-up-the-bank style screener with a static perforated steel plate on a steel frame, all mounted in a concrete inlet or check structure. In these types of screeners, brushes are mounted parallel to the bank and are chain-driven to sweep debris off the screens and up into a collection area on the bank. Operation is typically on a timer, but can be overridden by an operator when accumulations of debris are higher than normal, such as due to upstream mowing. Smaller systems can be remote-mounted and powered using solar panels to trickle charge a battery. However, these sweep-up-the-bank style systems have a history of problems, particularly with the adhesion of weeds onto the perforated steel plate.

Travelling screens are another way to remove debris at inlet, inline or canal check structures. In these types of screening devices, the entire screen is arranged in a conveyor belt like fashion and pulls the debris out of the water. Subsequent cleaning of the screen is accomplished with high pressure backwash nozzles mounted on the bank. Grade 304, 316 or 317 stainless steel screens are typically used in a belted configuration, the belting traveling at a speed of 7-8 feet per minute. An internal spray bar then uses high pressure water to blow off the debris material on the back side of the screen. Disadvantages of the travelling screen devices are that they often require additional power (to power both the continuously travelling screen as well as the high pressure water pumps), have additional complexity (including the need for a high pressure water system) and regardless of how clean the screen is kept, these screen will reduce the amount of water flow through the inlet, inline or canal check structure due to their conveyor belt-like nature (typically a travelling screen only allows approximate 60% of the normal flow rate through).

What is desired therefore is a novel apparatus which overcomes the limitations and problems of the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, wherein:

FIG. 1 is a perspective view of one embodiment of a weed and trash screening apparatus of the present invention, shown being suspended by straps and being lowered into position into a canal check structure;

FIGS. 2-5 are various perspective views the embodiment of FIG. 1, shown positioned within a canal check structure;

FIG. 6 is a cross-sectional view of the embodiment of FIG. 1 taken along line 6-6 in FIG. 2;

FIGS. 7a-7c are various perspective views the embodiment of FIG. 1, showing the hexagonal screen drum in various rotated positions;

FIGS. 8a-8b are various perspective views of the embodiment of FIG. 1, showing debris being swept of off the hexagonal screen drum into a lateral collection area, as well as a close up view the perforations in, and accordion style folding of, the screen drum; and

FIG. 9 is a perspective view of another embodiment of the hexagonal screen drum.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description is of a preferred embodiment by way of example only and without limitation to the combination of features necessary for carrying the invention into effect. Reference is to be had to the Figures in which identical reference numbers identify similar components. The drawing figures are not necessarily to scale and certain features are shown in schematic or diagrammatic form in the interest of clarity and conciseness.

Referring now in detail to the accompanying Figures, there is illustrated an exemplary embodiment of the weed and trash screening apparatus according to the present invention, the apparatus generally referred to by the numeral 10.

FIGS. 1-8b illustrate a preferred form of the invention 10 and show its use in a typical irrigation canal C adjacent to a check structure S, weir or other water delivery structure that discharges water W downstream into the remainder of the canal C. In this embodiment the check structure S is shown within a relatively small lined canal C. The object of the invention is to remove debris D such as algae, weeds and other trash that is carried within the water W of the canal C (upstream of the apparatus 10), so as to minimize subsequent pump and irrigation equipment damage downstream.

The apparatus 10 comprises a screen 12 rotatably mounted within a stationary rigid frame 14 that is adapted to abut the check structure S or other water delivery canal structure and further has a rear end 14r of the frame 14 adapted to be located downstream from its front end 14f along the canal C. During operation, at least a portion of the screen 12 is submerged within the water W and acts in a traditional manner to catch debris D and prevent said debris D from passing further downstream. The frame 14 is also positioned within check structure S at a height such that the top of the screen 12 is at least a couple inches above the water surface level within the canal C (such as by being lifted into place using lifting straps Z and a hydraulic lift). This positioning assures free flow of water W through the apparatus 10 and the screen 12 while also providing an opportunity to clean a top-most face 12tf of the screen 12 in the atmosphere and away from the water environment. Advantageously, the chance of debris D being dislodged and subsequently lifted by the flowing water to move downstream in the canal C is reduced significantly.

The frame 14 can be held stationary within the check structure S by frictional engagement of its various support members, or it can be rigidly mounted to the check structure S at its front end 14f. In any respect, the frame 14 is designed and located in such fashion as to insure that substantially all water W in the canal C will be directed onto the porous screen 12.

Unlike the conveyor belt screens of the prior art travelling screen device, the screen 12 of the present invention is substantially arranged in the form of a prism, i.e. having an n-sided polygonal base 12b forming a first end, a corresponding copy of that base 12c (i.e. not in the same plane as the first base) forming a second end, and n other faces 12f joining corresponding sides of the two bases 12b, 12c. In the preferred embodiment shown in FIGS. 1-8, as well as in the embodiment of FIG. 9, the screen is shaped substantially as a hexagonal prism or hexagon drum, i.e. wherein congruent hexagons form the top and bottom ends and the side faces are parallelograms or rectangles. However, other prism shapes can be utilized, such as a pentagonal prism or even a rectangular box (not shown).

Preferably, the screen 12 is made from perforated metal plate having a 51% open area or perforations 12o. More preferably, the metal plate of the screen 12 is a stainless steel, such as a grade 304, 316 or 317 stainless steel. Even more preferably, the metal plate of the screen 12 is 10 gauge stainless steel with ¼ inch diameter perforation providing the 51% open area. Yet even more preferably, the faces 12f of the screen 12 are corrugated or pleated to increase the surface area of each of the faces 12f and, hence, their total perforated open area.

The inventor has calculated that, using the hexagonal prism screen 12 of the preferred embodiment, by providing faces 12f each having a width of 24 inches, and by corrugating or pleating each face 12f so as to provide eight pleats 12p per face 12f, each approximately 4 inch high and being of substantially triangular cross-section, and providing a 2 inch base 12z between adjacent pleats 12p (see, for example the embodiment of FIG. 9, which more clearly shows the bases 12z between the pleats 12p), the effective open area is approximately 150% open, or allow 150% of the normal canal water W through the apparatus 10 when placed in an irrigation canal C as shown substantially in FIGS. 1-5.

The frame 14 is substantially rectangular in shape and substantially open to the flow of water W in the canal C. The screen 12 is rotatably mounted or journalled within the frame 14 about a pivot axis P which is substantially aligned with the screen's longitudinal axis A and positioned substantially along the horizontal plane. Preferably, the frame 14 has solid sides 14b, 14c, so as to direct the flow of water W through the interior of the frame 14 and through the screen 12. More preferably, the screen's bases 12b, 12c and placed substantially adjacent the frames sides 14b, 14c in a planar alignment (as shown in FIGS. 1-5) so that there is minimal clearance between the bases 12b, 12c of the rotating screen 12 and the frame's sides 14b, 14c and so that the majority of the water W in the canal C is directed through the screen 12 (rather than between the frame's sides 14a, 14b and the bases of the screen 12b, 12c as might otherwise be the case). Preferably the frame 14, and screen 12, are sized appropriately for the check structure S, weir or other water delivery structure that the apparatus 10 is intended to be placed adjacent to, so that substantially all of the water is directed through the screen 12.

The apparatus 10 further comprises screen rotating means 20, to periodically rotate the screen 12 within the frame 14, and screen face cleaning means 30, to periodically clean or sweep debris D off of one or more of the screen's faces 12f. Preferably, the screen face cleaning means 30 is mounted near to top end of the frame 14 so as to clean a top-most face 12tf of the screen. More preferably, the screen rotating means 20 rotates the screen 12 so that one of the faces 12f is oriented near the top of the frame, underneath the screen face cleaning means 30, substantially along the horizontal plane.

In the preferred embodiment of FIGS. 1-8b, the screen rotating means 20 is comprised of a conventional electric motor 20m that drives a belt 20b and pulley 20p attached to an axel shaft 20a which rotatably supports the screen 12 (at the bases 12b, 12c) and is mounted at pivot P (as more clearly shown in FIG. 3). Advantageously, the belt 20b and pulley 20p allow the electric motor 20m to be mounted near the top of the frame 14 and above the normal surface water W level that might exist within the canal C. More advantageously, appropriate gearing (not shown) can be provided within the motor 20m to allow proper torque and rotational to reach the axel shaft 20a to compensate for screen size, weight and water W flow forces, while still allowing the apparatus 10 to rotate or turn the screen 12 along the screen's longitudinal axis A. Those skilled in the art will recognize that other rotating or drive means can be used, such as waterproof electric motors directly driving the axel shaft 20a, gasoline or diesel powered engines (mounted above the water level), or supporting the screen 12 on a plurality of powered rollers or bearings (instead of supporting the screen via axel shaft 20a).

In the preferred embodiment of FIGS. 1-8b, the screen face cleaning means 30 is comprised of a broom 30b or similar cleaning tool consisting of stiff fibers and broom moving means 40 to support the broom 30b and to move it across one or more of the screen's faces 12f to allow broom 30b to sweep off debris D from said one or more of the screen's faces 12f. Preferably, broom 30b is supported above, and moveable across, the top-most face 12tf of the screen 12. More preferably, broom 30b is moveable along the longitudinal axis A of the screen 12 (and hence the longitudinal axis A′ of the frame 14) in an oscillating manner as more clearly shown by arrow O in FIG. 4.

Further in the preferred embodiment of FIGS. 1-8b, the broom moving means 40 is comprised of a carriage 42 slidably or moveably mounted on pair of transversely spaced rail members 44a, 44b mounted parallel to one another near the top end of the frame 14. The carriage 42, in turn, supports the broom 30b for oscillating movement O above the screen 12 and along the rail members 44a, 44b.

Preferably, the rail members 44a, 44b extend along the frame's longitudinal axis, above the screen 12. Sufficient clearance is provided to the rail members 44a, 44b so that, when the screen 12 is rotated or pivoted within the frame 14 at pivot P the screen 12 does not hit, touch or impact said rail members 44a, 44b. More preferably, the rail members 44a, 44b extend laterally along the frame's top for a distance that is more than the length of the screen 12 (as measured along its longitudinal axis), so that the carriage 42 that is mounted thereon (and the broom 30b carried thereby) can be positioned to at either end of the frame 14 (i.e. near and above sides 14b, 14c) so that it will not interfere with the rotation of the screen 12 at pivot P (see FIGS. 7a and 7b). In an alternate embodiment, broom moving means 40 further comprises lifting means (not shown) to lift the broom 30b sufficiently above the rail members 44a, 44b, to prevent broom 30b from interfering with the rotation of the screen 12, when said screen 12 is rotated during operation.

In the preferred embodiment of FIGS. 1-8b, broom 30b is a rotary broom driven by broom rotating means 50 (such as a conventional electric motor 50m) so as to rotate the broom along an axis R that is substantially perpendicular to the screen's longitudinal axis A and, hence, also substantially perpendicular to the longitudinal axis of the pleats 12p (see FIG. 6). Advantageously, the bristles of the rotary broom can easily sweep any debris D between the individual pleats 12p along axis A (see FIG. 8a, broom 30b shown schematically). More advantageously, by providing pleat bases 12z between the pleats, the likelihood of bristle damage to the broom (due to individual bristles being caught between the pleats or the perforations 12o) is significantly reduced.

Preferably, the broom moving means 40 further comprises carriage moving means 46 to slidable or rollably move carriage 42 along the rail members 44a, 44b in an oscillating manner O along the screen's face 12f and between ends 12b and 12c. More preferably, the carriage moving means 46 is a conventional rack and pinion rail system with a rack (not shown) mounted on the top of each of the rail members 44a, 44b and a drive pinion (not shown) and appropriate gearing positioned within the broom moving means 40 enclosure. Even more preferably, the pinion is driven by a conventional electric motor. Yet even more preferably, the electric motor 50m of the broom rotating means is also geared to drive the pinion of the carriage moving means 46. Yet even more preferably, the gearing of the electric motor 50 is such that the broom rotates R in such a manner so as to lift up, or kick forward, any debris D forward (in direction U) ahead of the broom's path of travel T, rather than sweep debris underneath the rotary broom (see FIGS. 4, 5 and 8a). Preferably, the screen face cleaning means 30 further comprises a cover positioned above the rotating broom 30b, so as to limit the amount of debris D being swept upwards and, instead, direct the debris D ahead of the broom's path of travel T. Advantageous, the rotating broom 30b will sweep off debris D from a screen face 12f in a similar fashion as a non-rotating broom would—i.e. sweep the debris D head of the brooms path of travel T. More advantageously, as the broom 30b is oscillated O across a screen face 12f, the debris D will be moved to the ends of the frame (near sides 14b, 14c).

Preferably a catch basin 60 or containment member is provided at either end of the frame (near sides 14b, 14c) wherein debris D can be collected and contained during operation of the apparatus 10. Advantageously, the debris D is removed from both the screen face 12f as well as from the canal C and the water W therein and is securely held within basins 60 where it can then be subsequently removed by an operator at periodic intervals.

More preferably, conventional mechanical or electronic timers or programmable logic controllers (not shown) are provided to control and actuate the operation of the screen rotating means 20, screen face cleaning means 30, broom moving means 40, carriage moving means 46 and broom rotating means 50. Even more preferably, a conventional solar panel (not shown) is provided to trickle charge a battery (also not shown) which in turn provides power in a conventional manner to the various electric motors, timers, programmable logic controllers and screen rotating means 20, screen face cleaning means 30, broom moving means 40, carriage moving means 46 and broom rotating means 50.

Operation:

During operation, and in a preferred embodiment, apparatus 10 is placed within a canal C so that the front end 14f of frame 14 abuts the check structure S and rear end 14r of the frame 14 is located downstream (as more clearly shown in FIGS. 2-5). During operation, at least a portion of the screen 12 is submerged within the water W and acts in a traditional manner to catch debris D and prevent said debris D from passing further downstream. In particular, those screen faces 12f located on the upstream end of the screen 12 will act to catch and hold debris D (see, for example, FIGS. 4 and 7a) as time is permitted to pass and more and more water W flows through the apparatus 10 and the screen 12.

If it were left unattended for any substantial time, the upstream end of the screen 12 would clog with debris D and be rendered inoperative. Therefore, after a predetermined amount of time, calculated for the particular canal C, water W flow and amount of debris D present, the screen 12 is periodically swept and cleaned by the screen face cleaning means 30. In particular, and in the preferred embodiment, this is accomplished as follows. First, if the broom 30b is not already positioned there, broom 30b is positioned at either end of the frame 14 (i.e. near and above side 14b or 14c, see FIGS. 7a-7c), using broom moving means 40. Then, using screen rotating means 20, the screen is rotated along axis A, in direction F (see FIGS. 7a-7c) so that the screen face 12f that was on the upstream side of the screen 12, and that caught the debris D (see FIG. 7a), is positioned substantially horizontal and level with the catch basins 60, so as to become a top-most face 12tf (see FIG. 7c). Then the screen face cleaning means 30 is actuated to clean the debris D off of the top-most face 12tf and move said debris D into basins 60 (see FIGS. 4, 5 and 8a). Preferably, screen face cleaning means 30 will make a preset number of oscillating sweeps across the top-most face 12tf, to ensure sufficient removal of debris D from the top-most face 12tf, before this operational cycle is repeated and the top-most face 12tf is subsequently rotated so as to be positioned in the water W downstream of the apparatus 10.

Observations:

The inventor has observed that, using the preferred embodiment of FIGS. 1-8b in a typical irrigation canal in southern, Alberta, Canada, the apparatus 10 operated for ten (10) days, turning the screen 12 every ten (10) minutes and oscillating O the rotary broom 30b twice along the top-most face 12tf, kept the apparatus 10 sufficiently clean of debris D to never have the flow of water W through the apparatus 10 go below the 100% flow rate of the check structure S. Moreover, the inventor observed a significant amount of debris D having been collected at the basins 60 and removed from the water W.

Advantageously, the apparatus 10 continuously maintained a screen 12 that provided a greater than 100% normal flow rate of water W, while removing debris D from the water W. More advantageously, the apparatus 10 is mechanically simple and does not require complex high pressure water cleaning sprays to maintain the screen 12 in a continuous clean condition. Even more advantageously, the apparatus 10 works day and night, and frees the user from the tedious task of manually cleaning the conventional screens used in irrigation canals and ditches.

Those of ordinary skill in the art will appreciate that various modifications to the invention as described herein will be possible without falling outside the scope of the invention.

Claims

1. A debris screening apparatus, for use adjacent a check structure in a canal having a flow of water, the apparatus comprising:

a frame substantially open to the flow of water and adapted to abut the check structure;

a screen having at least one face with a plurality of pleats, said screen mounted within the frame wherein, during operation, a first portion of the screen is submerged within the water, a second portion of the screen is above the water and wherein a portion of water in the canal is directed through the screen; and

screen face cleaning means operable to periodically clean debris off of the screen's at least one face.

2. The debris screening apparatus of claim 1 wherein there are at least eight pleats per said at least one face of the screen.

3. The debris screening apparatus of claim 1 wherein the plurality of pleats are of substantially triangular cross-section.

4. The debris screening apparatus of claim 3 further comprising a substantially flat base between adjacent pleats.

5. The debris screening apparatus of claim 4 wherein the pleats are each at least 4 inches high and the base between adjacent pleats is at least 2 inches wide.

6. The debris screening apparatus of claim 1 wherein the screen is made from perforated metal plate having at least a 51% open area.

7. A debris screening apparatus, for use adjacent a check structure in a canal having a flow of water, the apparatus comprising:

a frame substantially open to the flow of water and adapted to abut the check structure;

a screen having a plurality of faces, said screen rotatably mounted within the frame wherein, during operation, a first portion of the screen is submerged within the water, a second portion of the screen is above the water and wherein a portion of water in the canal is directed through the screen;

screen rotating means operable to periodically rotate the screen within the frame; and

screen face cleaning means operable to periodically clean debris off at least one face of the screen's plurality of faces.

8. The debris screening apparatus of claim 7 wherein each of the screen's faces has a plurality of pleats.

9. The debris screening apparatus of claim 8 wherein there are at least eight pleats per face of the screen.

10. The debris screening apparatus of claim 8 wherein the plurality of pleats are of substantially triangular cross-section.

11. The debris screening apparatus of claim 10 further comprising a substantially flat base between adjacent pleats.

12. The debris screening apparatus of claim 11 wherein the pleats are each at least 4 inches high and the base between adjacent pleats is at least 2 inches wide.

13. The debris screening apparatus of claim 7 wherein the screen is made from perforated metal plate having at least a 51% open area.

14. The debris screening apparatus of claim 7 wherein the screen is a prism.

15. The debris screening apparatus of claim 14 wherein the screen is a hexagonal drum.

16. The debris screening apparatus of claim 7 wherein the screen face cleaning means further comprises a broom and broom moving means operable to move said broom across at least one of the screen's faces.

17. The debris screening apparatus of claim 16 wherein the broom is a rotary broom driven by rotating means.

18. The debris screening apparatus of claim 8 wherein the screen is a prism.

19. The debris screening apparatus of claim 18 wherein the screen face cleaning means is operable to clean debris off of a top-most face.

20. The debris screening apparatus of claim 19 wherein the screen face cleaning means is operable to make a preset number of oscillating sweeps across the top-most face, prior to actuation of the screen rotating means.