AU2007100270A4

AU2007100270A4 - Screen Cleaner

Info

Publication number: AU2007100270A4
Application number: AU2007100270A
Authority: AU
Inventors: John Commins
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-04-05
Filing date: 2007-04-05
Publication date: 2007-05-24
Anticipated expiration: 2015-04-05

Description

SCREEN CLEANER Field of the invention THIS INVENTION relates to a apparatus for cleaning a screen and is more specifically, although not exclusively, concerned with cleaning a sloping screen formed by a grid of inclined but upright iron bars used to block the passage of trash carried by water along a land drainage ditch in which the screen is mounted.

State of the art Irrigation drainage ditches are used to convey large volumes of water and may be ten meters wide and of considerable length. Trash, washed or blown into the ditch over a period of time, will be carried along by water flowing in the ditch and, unless removed, can block the ditch and cause flooding of the surrounding land.

Drainage ditches are often provided with fixed, iron grid screens at pre-selected locations to collect the trash. These screens have parallel bars which slope upwardly, usually at an angle of sixty degrees, to the direction of flow of water through them. The iron grid screen is a large structure, often set into a concrete frame, and may be two and a half meters wide and extend upwardly above the height of the ditch. It may be provided with cleaning apparatus which can be intermittently operated to enable the screen to be cleaned from time-to-time. Such apparatus is permanently installed on the upstream side of the screen and may have a slat or slats which extends the width of the screen and which are dragged upwardly along its upstream face to transfer trash collected on the screen onto the upper surface of the slat. The collected trash is then dumped at a chosen collection point on the land alongside the ditch.

Screen-cleaning apparatus spends much of its time unattended in the open air between periods of use. It is then required to function correctly. Small details of design can have an adverse effect on the functioning of the apparatus and it is therefore important that the apparatus is designed to be robust and to have a relatively long working and trouble-free life.

Object of the invention An object of this invention is to provide improved screen-cleaning apparatus.

The invention In accordance with the present invention there is provided apparatus for cleaning trash from a screen and operating by dragging a cleaning slat up the upstream face of a screen, the slat having its opposite end-portions mounted in respective carriages which are each carried by a respective endless chain having one run defining a path of movement of the slat up the screen, the carriage being attached to the chain by a shaft pivoted for rotation about a horizontal axis, the orientation of the carriage about the shaft axis during its upward movement being determined by the engagement of wheels on the carriage with a guide plate fixed in the apparatus and terminating short of the underside of a drive sprocket around which a return bend of the chain passes at the upper end of its upward movement, a first stop on the carriage being positioned to abruptly engage a first part of the apparatus when the slat lies substantially in a first vertical plane with one edge facing downwards, and means on the carriage to retain its orientation with respect to the chain until it reaches a position on said return bend at which the carriage topples forwardly to bring said slat into a second vertical plane with said one edge uppermost.

Preferred features of the invention Preferably said means includes a member on the carriage which bears on the chain after the wheels have disengaged from the guide plate.

Suitably the member, which may comprise a bar projecting from the carriage, retains the orientation of the carriage with respect to the chain until the carriage reaches a predetermined position on the return bend at which the slat moves to the second vertical plane.

Suitably the apparatus includes a second guide plate parallel to the first guide plate and for engagement with the carriage wheels during the carriage descent into the ditch.

Conveniently the location of the slat in the second vertical plane is determined by the engagement of a relatively soft block on the carriage with a section of the chain running over said return bend.

Introduction to the drawings The invention will now be described in more detail, by way of example, with reference to the accompanying informal drawings, in which: In the drawings FIGURE 1 is diagrammatic side elevation taken along a part of a drainage ditch and shows a trash screen and associated screen-cleaning apparatus, partly broken away; and, FIGURE 2 is an enlarged isometric view of a carriage forming part of the apparatus.

Description of preferred embodiment Figure 1 shows a much simplified diagrammatic vertical section, partly broken away, of a drainage ditch 1 containing a screen 2 formed by a grid of upright iron bars sloping upwardly at sixty degrees to the direction of flow of water along the ditch. For convenience of description the screen 2 and an associated cleaning apparatus 3 is broken horizontally into three, vertically-spaced portions referenced and The flow direction of water in the ditch is denoted by the arrowll 0. Trash carried along the ditch by the water flowing through it, collects on the upwardly-sloping upstream face of the screen 2 and has to be removed from time-to-time by the apparatus to ensure a steady flow of water along the ditch.

The apparatus 3 is mounted in the ditch 1 on the upstream side of the screen 2 and operates by dragging a flat horizontal blade 4 having a bristled or fingered edge 5, up the inclined face of the screen. The blade 4 extends between opposite sides of the ditch and is set at an angle which is perpendicular to the plane of the screen 2 when the slat is carrying out screen cleaning. The apparatus illustrated in this example of the invention is equipped with a single cleaning blade 4 which is shown in figure 1 in three different positions it occupies when the apparatus is in use.

The opposite ends of the blade 4 are mounted in respective carriages 6 which are respectively arranged close to opposite sides of the ditch 1. Each carriage 6 is provided with a laterally-extending horizontal shaft 7 journalled for rotation about its axis in a hollow pivot 8 of an endless chain 9 shown in interrupted outline in figure 1. The chain 9 is formed with links (not shown) pivoted to one another to enable the chain 9 to run around an upper sprocket 12 driven by means (not shown). The chain also runs around a lower idler sprocket 13. The chain 9 provides two runs 10 and 11 which extend parallel to one another and to the screen 2. The direction of movement of each run is indicated by an arrow adjacent its reference line. In practice, the screen is about two and one half meters wide and its bars are set in a concrete frame (not shown) in the ditch 1. The ditch may have a substantial width upstream and downstream of the screen 2 of as much as ten meters or sometimes more.

The sprockets 12 and 13, the chains 9 together with two spaced guide plates 15 and 16 are mounted in a steel framework (not shown) The guide plates 15 and 16 extend parallel to the screen 2 and are located between the vertical planes of respective chains.

The marginal side edges of the guide plates 15 and 16 are engaged by wheels on the carriages 6 and act to control their orientation about their shafts 7 during operation of the apparatus as is described in more detail below.

Each end of each blade 4 is welded to a flat support surface 14 shown clearly in figure 2 and forming part of the carriage 6. The wheels on the carriage 6 take the form of guide wheels 21,22, and 23. Guide wheels 21 and 22 each comprise a pair of wheels arranged in tandem, and the third guide wheel is on its own. The guide wheels 21,22 and 23 are arranged to run along the faces of the marginal edge portions of the guide plates 15 and 16 to ensure the correct orientation of the carriage 6 as it travels around the path of movement of the chain 9.

As shown in figure 2, the carriage 6 is provided with a first stop formed by the wheel 23 and a second stop formed by a nylon pad 29 bolted to one limb of an angle bracket 28 welded to the carriage 6. The carriage 6 is also provided with a bar 30 of square crosssection the position of which is indicated in figure 1 by an interrupted outline, positioned to engage the chain 9 after the wheel 23 is raised above the level of the top of the guide plate 15 and detaches from it.

Operation of the preferred embodiment The orientation of the carriage 6 at different places on the chain 9 is shown in portions A and B of figure 1. Portion B of figure 1 shows the orientation of the carriage 6 as it travels up the upstream face of the screen 2. The bristled edge 5 of the blade 4 then engages the upstream face of the screen 2 to clean it. The perpendicular angle of the blade 4 to the screen ensures that it retains collected trash on its upper surface. This orientation of the blade 4 is maintained by the wheels 21,22 which engage the upstream surface of the side margins of the guide plate 15. The weight of the carriages 6, the blade 4, and the trash collected on it, is carried by the two shafts 7 which are journalled into the pivots of respective chains 9 attached to opposite ends of the blade 4.

The upper left-hand portion A of figure 1 shows what happens as the carriage 6 approaches the drive sprocket 12. It will be noted that the guide plate 15 terminates at its upper end short of the level of the sprocket 12. This allows the wheels 21,22 and 23 to disengage in turn from the upper end of the guide plate 15. When the wheels 21 and 22 have disengaged from the plate 15 but before the wheel 23 disengages, the weight of the blade 4, and the trash on it, causes the carriage 6 to rotate quite violently in a counterclockwise direction around the axis of the shaft 7 to the position shown and at which the blade 4 is vertical. This rotational movement is abruptly halted at this position as it is determined by the sudden engagement of the wheel 23 with the underside of the guide plate 15. This results in the bulk of the trash being dislodged from the slat 4 although a small amount may still adhere to the upper edge of the slat 4. The dislodged trash falls downwards onto a dump or some other form of trash-collection device (not shown) positioned above the downstream side of the screen 2.

The upwards movement of the chain continues and causes the wheel 23 to disengage from the upper end of the guide plate 15. The carriage 6 can then further rotate in the counter-clockwise direction through a small angle until the bar 30 bears on the chain 9.

This prevents further counter-clockwise rotation of the carriage 6 about the axis of the shaft 7 and holds the orientation of the carriage with respect to the chain until the end of the upward run 10 is reached.

The carriage 6 now moves with the return bend of the chain 9 in a clockwise direction until its centre of gravity passes through the vertical plane. The carriage 6 then topples forwardly in a clockwise direction around the axis of the shaft 7 until the nylon block 29 strikes the portion of the chain still engaging the sprocket 12 at the top of the return bend 11 of the chain. This occurs when the slat 4 is again substantially vertical but inverted with respect to the orientation it had when the bar 30 first contacted the chain. Residual trash clinging to the edge of the vertical but inverted slat 4 now dislodges from the slat 4.

The carriage continues traveling down along the return run 11 of the chain 9 with its wheels 21,22 and 23 engaging the marginal edge of the guide plate 16 as shown on the right-hand side of portion A. The orientation of the carriage 6 is maintained by this engagement, even when trash floating on the surface of the water in the ditch I is struck by the descending slat and which might otherwise urge the carriage 6 to move in a counter-clockwise direction.

7 Finally the carriage reaches the end of its descent and is guided around the lower sprocket 13 to recommence its upward movement along the face of the screen 2 in readiness to perform the next screen-cleaning operation when required.

Claims

2. Apparatus as claimed in Claim 1, in which said means includes a member on the carriage which bears on the chain when the wheels disengage from the guide plate.
3. Apparatus as claimed in Claim I or Claim 2, in which the member retains the orientation of the carriage with respect to the chain until the carriage reaches a predetermined position on the return bend at which the slat moves to the second vertical plane.
4. Apparatus as claimed in any one of the preceding Claims, which includes a second guide plate parallel to the first guide plate and for engagement with the carriage wheels during the carriage descent into the ditch.
5. Apparatus as claimed in any one of the preceding claims, in which the location of the slat in the second vertical plane is determined by the engagement of a relatively soft 1 block on the carriage with the upper surface of a section of the chain running over said return bend. Dated this 3 rd day of April 2007 JOHN COMMINS (Applicant's Patent Attorney)