AU7727681A - Self cleaning filter - Google Patents

Description

"SELF CLEANING FILTER"

This invention relates to a self cleaning filter such as may be used in an irrigation system,

Background of the Invention

With the advent of irrigation systems where the irrigation water is sprayed through small nozzles, or where the irrigation is carried out by drip irrigation, it is essential that the water be filtered before passing to the spray nozzles or drip units otherwise these would readily clog 'with the particles carried in suspension in the water. Thus it is necessary that filter units be supplied and that some way be provided for effectively cleaning these filter units. While it is known that filter units can be dismantled and manually cleaned or replaced, this procedure is not entirely satisfactory.

Also filtering units are known where a reverse flow can flush the collected filtered material from the filter, this being flushed through an exhaust port. However these rely solely on the flow of water and thus an effective cleaning is not always carried out. An example of this has applied to a cartridge of particulate filter medium is shown in Australian Patent No. 420747.

U.S. Patent No. 4060483 discloses a method and apparatus for effecting the cleaning of a fluid filter by a hollow filter cleaning body having an inlet situated in close proximity to the filter member, the flow of water through the cleaning body causing movement of the cleaning body, the cleaning water then flowing through an exhaust port.

Brief Description of the Invention Thus there is provided according to the invention a self cleaning filter unit, the unit having a liquid inlet and a liquid outlet, a filtering member disposed between said filter inlet and filter outlet, an exhaust outlet, means disposed within said filter unit for moving a filter cleaning element over said filter element to remove filtered material therefrom, and means driving said filter cleaning element responsive to flow of fluid from said filter cleaning element through said exhaust to sweep away said filtered material through said exhaust.

Brief Description of the Drawings

In order to more fully describe the invention, reference will now be made to the accompanying drawings in which:

FIG. 1 is a longitudinal cross-sectional view of the invention, and

FIG. 2 is a cross-section on the lines 2-2 of FIG. 1 on an enlarged scale.

Description of the Preferred Embodiment

In a preferred form of the invention the filter unit can comprise a generally cylindrical casing 1 having an inlet 2 and socket 3 toward one end and an outlet 4 and socket 5 toward the other end. Within the casing there is disposed a cylindrical filter element 6, the element being mounted in rings 7 which are sealed by sealing members 8 to the interior of the cylindrical casing 1. The cylindrical filter element 6 is positioned such that the fluid will flow in through the inlet 2 into the interior of the casing at that end and then through the interior of the filter 6, and after passing through the filter element 6 is discharged through the outlet port 4. The inlet flows from the inlet 2 through a course prefilter portion 6a into the interior of the filter 6.

The cylindrical casing 1 at the inlet end is closed by an end cap 9 provided with suitable sealing rings 10, the cap being maintained in position by a longitudinal rod 11 passing through the filter unit to be secured to the end cap 12 at the outlet end of the filter unit. This second end cap is provided with an exhaust outlet 13 and sealing rings 10, with the rod 11 supporting on a bush 14 and thrust bearing 15 a water turbine 16 between the end cap 12 and the adjacent ring 7. The water turbine 16 has two arms 17 extending radially, each arm having an aperture 28 so that the water is discharged tangentially to cause the turbine to rotate. This water turbine 16 is connected to a hollow member 17 surrounding said rod and extending through the filter element and supported on the rod 11 by a bush 18 at the ring 7 adjacent the inlet 2 to the casing 1. The hollow member 17 is shaped to have a portion 19 adjacent to the inner surface of the filter 6 , where the member 17 is provided with a series of slits, holes or apertures 20. The hollow member 17 is also provided with a longitudinal brush element 21 supported from the hollow element by suitable arms 22 or the like. The brush element is adapted to contact the interior of the filter element for cleaning the filtered material therefrom. A drive housing 23 surrounds the turbine 16, and has a radial wall 24 and a sealing ring 25 to seal the turbine drive area from the filter area except through the hollow member 17.

The exhaust 13 can be provided with a suitable flow control, and in normal operation of the filter device this exhaust valve is closed so that the water will flow from the inlet 2 through the interior of the filter element 6 and to the outlet port 4. At this time also the hollow element 17 and the turbine 16 will be filled with water. The thrust bearing 15 carries a disc 26 to help break up the turbulance from the turbine and allow the water to flow through the exhaust.

However on opening the exhaust port fluid will flow from the interior of the filter element through the hollow member and through the water turbine to drive the turbine to rotate the hollow element with the brush attached thereto so that the brush then sweeps over the interior of the filter element. The flow of water as it sweeps past the filter and into the hollow through the slots will carry with it the debris and filtered material which has been removed from the filter element by the brush and this material is then discharged to waste through the exhaust port.

The hollow element may have a plurality of apertures therein to allow the water to flow therethrough, or could have a longitudinal slit or plurality of slits, which slits can be positioned in relation to the filter and the brush to that as the element and brush rotate the disturbed filtered material and debris would immediately be swept through the slit. The slit is preferably positioned in the vicinity of the filtering element so that as the water flows through the slit it will carry with it the debris and filtered material loosely adhered to the filtering element.

The control of the filter unit by the valve positioned in the exhaust aperture or in the exhaust line can be manually operated or alternatively be controlled automatically either by sensing the back pressure in the filter, or alternatively be controlled by a timer or some other control such as the quantity of water which has passed through the filter.

One suitable form of valve is that shown in Australian Patent No. 508284 entitled "Automatic Filter Backwash Control".

The filter element with its sealing rings and the hollow member and the turbine can be readily assembled into the outer cylindrical casing through the ends of the cylindrical casing and are retained in position by the longitudinal rod and the end caps.

It will be realised that various forms of water turbines can be provided, that is being either the reaction or impulse type and either operated by way of the use of curved vanes or jets or the like.

It will be seen that by the action of the brush passing over the filter element that this readily disturbes the collected material therefrom, this not only being suspended particles being carried by the water, but also any accumulated algae or slime or the like which tends to collect on these components. The brush then disturbs these filtered materials and these are then easily carried away by the flow through the exhaust port.

This can be carried out during the normal operation of the filter or alternatively the flow through the outlet port can be stopped during the filter cleaning operation but in normal practice the cleaning would take place during the normal operation of the filter.

O PI A 1PO -*_*y , Although one form of the invention has been described in some detail it is to be realised that the invention is not to be limited thereto but can include various modifications falling within the spirit and scope of the invention.

Claims (6)

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:-

1. A self cleaning filter unit, said unit comprising a cylindrical housing, an inlet at one end of said housing and an outlet at said other end, a circular filter element supported by sealing rings engaging the interior of said housing, characterised by a tubular element supported on a rod extending through said housing and connected to a turbine, an exhaust outlet in an end cap adjacent said turbine, said tubular element having a portion adjacent to the interior of said filter element, openings in said portion opening into the interior of said tubular element whereby fluid can flow through said inlet into the interior of said filter element through said filter to said outlet, and when said exhaust is open, fluid flows from the interior of said filter element through said openings into the tubular element to said turbine which rotates said tubular element sweeping the filtered material from said filter through said exhaust.

2. A self cleaning filter unit as defined in Claim 1 further characterised by a brush carried by said tubular element and adapted to sweep the interior of said filter element ahead in the direction of rotation of said portion of said tubular element.

3. A self cleaning filter unit as defined in Claim 1 further characterised in that said turbine is mounted in a drive housing having a radial wall adjacent the adjacent sealing ring, a further seal sealing said radial wall to said tubular member, said tubular member having a hollow portion passing through said further sealing ring and connected to said turbine.

4. A self cleaning filter unit as defined in Claim 3 further characterised in that said turbine has a pair of hollow radial arms, a tangential aperture in each arm through which water will pass to- cause the turbine to rotate.

5. A self cleaning filter unit as defined in Claim 1 further characterised in that said turbine is spaced from the adjacent end cap by a thrust bush carrying a circular baffle.

6. A self cleaning filter unit substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.