Abstract:
A self-cleaning filter system is disclosed that includes an inlet fitting that is adapted to be inserted into an existing filter body. A spray tube having a plurality of outlets that slideably engages the inlet fitting, is positioned in the ring discs of the existing filter and a compression member proximate to one end of the ring discs applies a compressive force to the ring discs. When fluid enters the spray tube from the inlet fitting compression on the ring discs is reduced to allow the ring discs to separate while fluid pressure is simultaneously imposed on the ring discs through a plurality of outlets to clean the filter component. The parts included with the system may be used to convert a manual filter into a self-cleaning filter system.

Description:
BACKGROUND  
     37 C.F.R. § 1.77(b)(5)  
       [0001]     The present invention relates to filters and more particularly to a self-cleaning filter systems. The self-cleaning filter system cleans ring disc media effectively without the need to open and clean the filter manually.  
         [0002]     Ring disc filter elements were originally developed to filter hydraulic fluid for military aircraft and have gradually found widespread use in agricultural irrigation and in industrial applications. Ring discs are highly efficient in their ability to filter particulates from fluids. The ring discs are diagonally grooved on both sides to a specific micron size. A series of the ring discs are then stacked and compressed on a spine. When stacked, the grooves on top of each disc runs opposite from the grooves below it, creating a filtration system having a series of grooves and traps for solids.  
         [0003]     Agricultural irrigation systems that use ring disc filters are typically large scale and require high flow, high volume filters. It is typical for filters used in large-scale agricultural irrigation systems to exceed a flow rate of 25 gallons per minute. The large-scale ring disc filters that have the ability to provide back flushing of the ring discs tend to include complex mechanisms. For example, complex flapper type valves for controlling the flow direction are shown in U.S. Pat. Nos. 4,655,910 and 4,655,911. Other complex back flushing ring disc filters use a funnel shaped rubber sleeve to control the flow direction. For example, see U.S. Pat. No. 6,398,037. A spring loaded valve system is another complex approach that is shown in U.S. Pat. No. 6,419,826.  
         [0004]     Because of the effectiveness of ring disc filter systems, their use has spread into smaller applications such as plant nurseries, greenhouses and wastewater treatment systems. They are also now being used in such industries as food and beverage, pulp and paper, mining, textile, chemical, pharmaceutical, electronic, refinery, power generation, and aquaculture. Typically, for small-scale applications, the ring disc filters are manual, non-backflushing filters. Backflushing reduces the frequency of required disassembly of the filter and ring discs, improves the operation of the filter system and it reduces labor costs.  
         [0005]     Because the majority of self-cleaning filter systems are limited to applications where flow rates typically exceed 25 gallons per minute, water systems with lower flows must rely on manual filters or partially self-flushing filters.  
         [0006]     Manual filters do not have any mechanism for backflushing while partially self-flushing filters are used together with valves that reverse the direction of fluid flow to flush particulate matter out of the ring disc media. The partially self-flushing filters are an improvement over the manual filters but because of the structure of ring disc filter media, tend not to be effective in removing particulate matter. Particles can become lodged in the grooves in the surfaces of the ring discs and water that is simply flushed back through them in the reversed direction does not direct enough velocity at the grooves of the discs necessary to remove the particles. Furthermore, the ring discs tend to stay compacted together and the generalized fluid flow does not separate the ring discs sufficiently to allow fluid flow to be directed to the grooves in the ring discs or around the grooved surfaces of the ring discs.  
         [0007]     Ring disc filter manufacturing companies have not found it cost effective to manufacture small, self-cleaning filters. As a result, there is a need for a low volume, low flow rate, self-cleaning filter.  
       SUMMARY OF THE INVENTION  
     37 C.F.R. § 1.77(b)(6)  
       [0008]     The invention involves a self-cleaning filter system. Manual filter systems include a filter body with an inlet and an outlet, a filter cover and ring disc filter elements. The improvement includes an inlet fitting that is adapted to be inserted into the filter body. A spray tube that has a plurality of orifices slideably engages the inlet fitting. The spray tube is positioned inside of the ring discs that are contained in the filter cover. A compression member proximate to one end of the ring discs applies a compressive force to the ring discs. When fluid flows into the filter body through the spray tube to clean the ring discs, fluid flows through the spray tube and against the compression member. The pressure acting against the compression member reduces the compression on the ring discs allowing them to separate. During the cleaning process, the reversed fluid flow flows out of the orifices in the spray tube toward the ring discs.  
         [0009]     The outlets in the spray tube are at an oblique angle relative to the wall of the spray tube. Fluid that is forced through the outlets at an oblique angle directs pressure against the ring discs also at an oblique angle. This causes the ring discs to spin which helps to agitate particles on the grooves on the ring discs. The outlets can also be at an upward angle to force the ring discs upwardly. By forcing the ring discs upwardly, the ring discs are separated effectively, even the ring discs on the lower part of the stack.  
         [0010]     Compression can be applied to the ring discs in several different ways. In one preferred embodiment, an external compressor is positioned outside of the filter cover that engages a compression rod to apply compression to a compression plate above the ring discs. The external compressor may either use a spring compressor or a hydraulic compressor. In another preferred embodiment, a spring is positioned inside of the filter cover that imposes pressure on a compression plate. In another alternative embodiment, the internal spring and an external compressor are used to compress the compression plate and the ring discs.  
         [0011]     The invention can also be used to convert an existing manual filter into a self-flushing filter so that the resulting converted manual filters may be economically used for low volume and low flow rate applications. Unlike the prior art, the invention does not require a complex internal mechanism.  
         [0012]     The spray tube of the invention directs high velocity fluid into spaces between ring discs to clean particles and residual materials from grooves in ring discs. After installing the self-cleaning kit, the resulting filter operates more efficiently than a manual filter, does not require regular cleaning and therefore requires less labor costs to operate.  
         [0013]     To clean the self-cleaning filter system, the operator simply directs flow through the spray tube, restricts flow exiting from the outlet and allows flow to exit the inlet. Control of the flow may be achieved with conventional methods of manual valves or electric valves. The procedure can be automated with the use of a computer control system that is interfaced to the electric valves or other flow control devices.  
         [0014]     Because the frequency of required cleaning of the ring discs is determined by the amount of particles and solids that are build up on and around the ring discs, the self-cleaning filter system can be further automated by sensing the pressure differential between the inlet flow and the outlet flow. At a predetermined pressure differential, which corresponds to a predetermined amount of contamination, the outlet is closed, flow to the spray tube is opened, and the filter is flushed. The predetermined pressure differential can trigger an alarm that alerts an operator to flush the filter, or a computer can control the valves to flush the filter automatically without human intervention.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     37 C.F.R. § 1.77(b)(7)  
     Eight (8) sheets of drawings are attached.  
       [0015]      FIG. 1  is the outside view of a prior art ring disc filter assembly.  
         [0016]      FIG. 2  is a cross section view of a prior art ring disc filter assembly.  
         [0017]      FIG. 3  is an assembly drawing of an embodiment of the self-cleaning filter system including a spring compressor.  
         [0018]      FIG. 4  is a cross section view of an embodiment of the self-cleaning filter system including a spring compressor.  
         [0019]      FIG. 5  is a cross section view of an embodiment of the self-cleaning filter system showing the inlet and exit flow paths and including a spring compressor together with an internal spring.  
         [0020]      FIG. 5   a  is an isometric view of a portion of the ring disc filter elements in the normal compressed filtering mode.  
         [0021]      FIG. 6   a  is an outside view of an embodiment of the self-cleaning filter system that includes a spring compressor.  
         [0022]      FIG. 6   b  is a partial view of an embodiment of the self-cleaning filter system that includes a hydraulic compressor.  
         [0023]      FIG. 6   c  is a partial view of an embodiment of the self-cleaning filter system that includes an internal spring.  
         [0024]      FIG. 7  is the self-cleaning filter kit of  FIG. 4 , showing the effect of reversed flow on the spray tube, compression plate and ring discs.  
         [0025]      FIG. 7   a  is an isometric view of a portion of the ring disc filter elements in the normal compressed filtering mode.  
         [0026]      FIG. 8  is the cross section, taken on line  9 - 9  in  FIG. 3 , showing the tangential direction of the orifices.  
         [0027]      FIG. 9  is a side view of the part shown in section  FIG. 8 .  
         [0028]      FIG. 10  is a side view of the part shown in  FIG. 9  showing the orifice upward angle.  
         [0029]      FIG. 11   a  is a view of the top of a ring disc, including a section view of the spray tube and spine legs, taken on line  11   a - 11   a  in  FIG. 7 .  
         [0030]      FIG. 11   b  is a view of the bottom of a ring disc, including a section view of the spray tube and spine legs, taken on line  11   b - 11   b  in  FIG. 7 .  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
     37 C.F.R. § 1.77(b)(8)  
       [0000]     Prior Art Manual Filter:  
         [0031]      FIG. 1  shows the outside view of a conventional prior art manual ring disc filter assembly generally referred to by the letter A.  FIG. 2  shows a sectional view of the manual ring disc filter assembly A of  FIG. 1 . The manual ring disc filter assembly has a body  10  that includes an inlet  16  and an outlet  18 . The housing  12  is attached to the body  10  with a threaded securing ring  14 . On the top of the cover  12  is a port  20  that is generally provided molded in, undrilled and untapped as shown in  FIGS. 1 and 2 . An inlet pressure measuring port  22  and an outlet pressure measuring port  24  are provided to allow pressure measurements to be taken to determine the pressure drop across the ring disc filters  32 . The inlet pressure measuring port  22  and outlet pressure measuring port  24  may secondarily be used to drain fluid from the inlet  16  and outlet  18 , respectively. A stack of ring discs  32  are located on the spine  34  and positioned on the top of the flow diverter  41 . The spine  34  includes several spine legs  34   a  that extend from a compression plate  30  that is positioned on the top of the stack of ring discs  32 . The spine legs  34   a  in the conventional filter A include cross members  35  that provide structural support to the spine legs  34   a  and to the ring discs  32  before and after assembly. An internal spring  27  urges the compression plate  30  downwardly and compresses the ring discs  32  together. The spring is uniform in diameter along its length and is held in position on the compression plate  30  with a raised ring  27   a.    
         [0032]     As is known, the detailed view of the ring discs in  FIGS. 11   a  and  11   b,  show ring discs  32  having grooves  32   a  and ridges  32   d  that radiate outwardly on their surfaces. The enlarged view of the grooves  32   a  and ridges  32   d  are shown in  FIGS. 5   a  and  7   a.  When the bottom surface  32   f  of a ring disc  32  is placed on top of the top surface  32   e  of another ring disc  32 , the direction of the grooves  32   a  and ridges  32   d  run in opposite directions, thereby creating an intersection of the grooves  32   a  and  32   d.  The intersections  32   g  of the grooves  32   a  and ridges  32   d,  best seen by the hidden lines in  FIG. 5   a,  trap solid particles to prevent them from passing through between the ring discs  32 , but allow fluid to pass. The ring discs  32  are typically constructed of polypropylene or other polymer material, depending upon the fluid being filtered.  
         [0033]     During normal operation of the prior art device A, fluid of the inlet flow  16  to be cleaned enters the filter body through the inlet  16 . The flow diverter forces the fluid to travel up and around the ring discs  32 . The fluid is then forced to travel between the ring discs  32 . Particles that are contained in the fluid are trapped at the intersections  32   g  between the grooves  32   a  and ridges  32   g  of the ring discs  32 . The filtered fluid that has passed between the ring discs  32  travels down the open filtrate flush space  32   b  of the ring discs  32  and out the outlet  18 . Over time, particles build up in the grooves  32   a  and particles and other solid matter collects on the outside of the ring discs  32 . The build up of particles reduces the efficiency of the filtration and in time, can totally block the flow of fluid into or out of the filter.  
         [0034]     To clean the manual filter, the filter ring cover  12  must be removed, and then the ring discs  32  must be removed and sprayed with water or other cleaning fluid. Alternatively, a conventional backflush may be performed by reversing the flow direction in an attempt to free particles from the grooves  32   a  in the ring discs  32 . The backflush operation is performed by first opening the inlet  16 , then directing backflush fluid flow  18   b  into the outlet  18  to force flushing fluid to flow out from the bore  32   b  of the ring discs  32  and then out as backflush fluid flow  16   b  from the inlet  16 . The fluid traveling out from the bore  32   b  of the ring discs  32  is intended to carry solid particles along with it out the filter inlet  16 . However, it is rarely, if ever effective to try to clean the manual filter simply by reversing the fluid flow direction. The ring discs  32  are compressed together and the particulates trapped in the ring disc grooves  32   a  and at the intersections  32   g  of the grooves  32   a  and ridges  32   d  are generally not easily removed. As a result, the manual filters typically must be disassembled and cleaned by hand, either regularly or periodically with backflushing performed between manual disassemblies.  
         [0000]     Self-Cleaning Filter Apparatus:  
         [0035]     An assembly drawing showing a manual filter A with the improved elements of an embodiment of the invention is shown in  FIG. 3 . The improved elements may be included as an overall filter assembly B or may be provided as a kit to convert an existing manual filter A into a self-cleaning filter assembly B. The overall self-cleaning filter assembly is referred to generally by the letter B. A sectional view of the manual filter A with the self-cleaning kit installed is shown in  FIGS. 4 and 5 . An opening  25  is first formed in the body  10  sufficiently large for the inlet fitting  40  to be inserted. Before inserting the inlet fitting  40  into the opening  25  created in the body  10 , a sealant, such as epoxy or other waterproof sealing material, is applied to the outside of the inlet fitting  40  and on the inside of the opening  25  of the body  10  before inserting into the opening  25  in the body  10 . The sealant generally extrudes out of the opening  25  during assembly as shown at  40   a.  Alternative sealing techniques, such as thermo bonding between the polymeric materials, or other bonding techniques may also be used.  
         [0036]     A spine  34  having spine legs  34   a  and a compression plate  30  is assembled on a spray tube  36 . The spine legs  34   a  are generally affixed to the spray tube  36  with epoxy or other water proof adhesive material. The spine legs  34  have a tapered entry taper  34   b  at the end opposite from the compression plate  30  to allow for easier assembly of the ring discs  32  onto the spine  34 . In the illustrated embodiment, the spine legs penetrate and are attached to the compression plate  30 , as best seen in  FIG. 3 . Alternative spine  34  constructions are also contemplated. Although the spine legs  34   a  are affixed to the spray tube  36 , they may be removable from the spray tube  36 . The spray tube  36  is sealed at the top to the bottom side of the compression plate  30  in the position identified as  30   a.    
         [0037]     The ring discs  32  are placed onto the spine legs  34   a  and then the spray tube  36  is inserted into the bore  40   b  of the inlet fitting  40 . The bore  40   b  of the inlet fitting  40  has a groove  40   c  in which an o-ring seal  37  is positioned to provide a dynamic sealing surface between the spray tube  36  and the inlet fitting  40 . The o-ring seal  37  may also be replaced with an alternative seal member. The o-ring seal  37  allows the spray tube  36  to move up and down relative to the inlet fitting  40  while retaining a fluid seal between the outer surface of the spray tube  36  and the bore  40   b  of the inlet fitting  40 .  
         [0038]     Several small nubs  41   a  are positioned inside of the flow diverter. The spine legs  34   a  contact the nubs  41   a  to prevent the spray tube  36  from rotating.  
         [0039]     After inserting the lower end of the spray tube  36  into the inlet fitting  40 , the ring discs  32  are positioned on top of the flow diverter  41 . On the upper end of the spine  34 , the upper surface of the ring disc  32  on the top of the stack of ring discs  32  is in contact with the lower surface of the compression plate  30 . After the spray tube  36 , spine  34  and ring discs  32  have been installed into the filter body  10 , the filter cover  12  is installed on the filter body  10  and secured with the securing ring  14 .  
         [0040]     In  FIGS. 3, 4 ,  5 ,  6   a  and  7  a spring compressor body  50   a  is shown connected to the top of the filter cover with a threaded connection at the port  20 . The port  20 , on the existing filter cover  12  in the prior art device of  FIGS. 1 and 2  can be drilled and tapped with threads if it has not been previously adapted to receive a threaded member. A compressor spring  52  ( FIG. 3 ) is contained within the compressor body  50   a.  A compression rod  58 , which is limited by the compressive strength of the compressor spring  52 , extends out of the bottom of the spring compressor  50 . As shown in  FIG. 4 , after the compressor body  50   a  is threaded into the port  20 , the compression rod  58  extends and contacts the top of the compression plate  30 . The upward travel of the compression rod  58  is limited by the compressor spring  52  and the resulting compression is transferred to the compression plate  30 . Collar  26  in the cover  12  may be engaged by the compression plate  30  to limit the upward travel of the compression plate  30 . The compression plate  30  exerts compression onto the stack of ring discs  32  to hold each of the individual ring discs  32  close together. The resistance of the compression provided by the compressor spring  52  can be varied to increase the compression of the ring discs  32 . As shown in  FIG. 5 , additional downward compression may also be provided by inserting an internal spring  54  between the inside of the top of the filter cover  12  and the top of the compression plate  30 . Depending on the strength of the springs  52  and  54 , it is also possible to use the internal spring  54  by itself without the external compressor  50  (See  FIG. 6   c ). The configuration that excludes the external compressor body is advantageous in situations where available space for the filter assembly is limited.  
         [0041]     When the internal spring  54  is used by itself a button  55  on the lower end of the spring  54 , which has a hole positioned at its center, engages a post  53 . The post  53  is secured to the compression plate  30  and ensures that the spring  54  stays in the proper position on the center of the compression plate  30 .  
         [0042]     The desired amount of compression can vary according to the demands placed on the self-cleaning filter system B. In general, systems that use higher flow rates and higher pressures may require a higher compression on the stack of ring discs  32 .  
         [0043]      FIG. 6   b  shows a hydraulic compressor  56  that performs a function similar to the spring compressor  50 , but uses hydraulic pressure instead of compression from a spring. The hydraulic compressor  56  includes a compressor body  56   a  that houses a hydraulic compressor piston  57 . The hydraulic compressor piston  57  engages the compression rod  58  to compress the compression plate  30  and the stack of ring discs  32 .  
         [0044]      FIGS. 4 and 5  show the self-cleaning filter assembly B in the compressed mode. The filter assembly is usually in the compressed mode during normal filter operations. During normal filter operations inlet flow  16   a  enters the filter body  10  through the inlet  16  ( FIGS. 4 and 5 ). The flow is directed to the outside of the ring discs  32  by the flow diverter  41 . Fluid must then flow through the spaces or gaps between the grooves  32   a  on the ring discs  32  ( FIGS. 5   a  and  7   a ) and into the space between the spray tube  36  and the inside of the ring discs  32 . This annular filtrate flush space between the spray tube and the ring discs is identified as  32 c in  FIGS. 11   a  and  11   b.  The ring discs  32  trap particles from the fluid that travels between them in the grooves  32   a  ( FIGS. 5   a  and  7   a ). The depth of the grooves  32   a  generally determines the size of the particles that can pass between the ring discs  32 . Shallower grooves  32   a  will trap smaller particles and deeper or wider grooves  32   a  will let smaller particles pass and will only trap larger particles. The fluid that has passed through the ring discs  32  exits the filter cover  12  and filter body  10  through the outlet  18  as filtered outlet flow  18   a.  During normal operation, when the self-cleaning filter assembly B is in the compressed mode, a conventional manual or electric valve, or other flow control device (not shown) is used to prevent flow from entering into the inlet fitting  40  or into the spray tube  36 .  
         [0045]     The self-cleaning filter assembly B in  FIG. 7  is shown in the self-cleaning mode. A valve or other flow control device is used to stop flow from exiting at the outlet  18 . Flushing flow  15  is then allowed to enter the spray tube  36 . The flushing flow  15  travels up the spray tube  36  and is forced to flow out of the orifices  38 . The upward flushing flow  15  also directs pressure to the bottom surface of the compression plate  30 . The upward pressure on the compression plate forces the compression rod upwardly into the spring compressor  50  or hydraulic compressor  56 . The compression plate may travel as far up as bottom edge of the collar  26 . Because the compression plate is forced upwardly, the compression on the ring discs  32  is removed, which allows them to travel upwardly. The upward travel provides space or gaps between the ring discs  32  as shown in  FIG. 7   a  so that particles and debris may be flushed from the grooves  32   a  on the surfaces of the ring discs  32 .  
         [0046]     Three rows of multiple orifices  38  are preferably located along the length of the spray tube  36  ( FIG. 3 ). Although in the preferred embodiment, the rows of orifices  38  are uniformly distributed about the circumference of the spray tube  36 , it is contemplated that additional rows may also be added either uniformly distributed or in a staggered pattern.  
         [0047]     The orifices  38  are illustrated in detail in  FIGS. 8-9  and show that they are typically angled tangentially relative to the wall of the spray tube  36 . Because the orifices  38  are angled relative to the wall of the spray tube  36 , water that is forced out of the orifices  38  strikes the ring discs  32  obliquely, thereby causing the ring discs  32  to spin. The spinning action of the ring discs  32  disrupts particles that are in the grooves  32   a  of the discs  32  ( FIGS. 5   a  and  7   a ). The spinning action and the movement of the ring discs  32  causes turbulent flow, which further helps to agitate debris and particles that may be trapped on the grooves  32   a  of the ring discs  32 . The turbulence and agitation of the fluid about the surfaces of the ring discs  32  is effective to cause trapped particles and solids to be flushed free. The orifices  38  may also be angled upwardly, as shown in  FIG. 10 . The orifice upward angle  38   a  is preferably 1-3 degrees above horizontal but smaller or larger angles of inclination may be used. When fluid is forced out of the orifices  38 , the orifice upward angle  38   a  directs the fluid flow toward the discs  32  at a correspondingly upward angle. The resulting upward force imposed on the discs  32  urges them upward on the spine  34 , which helps to create spaces or gaps between the individual discs  32  ( FIG. 7   a ). In addition, the upward force on the ring discs  32  from the fluid flow overcomes the problem of the lower discs  32  tendency to stay close together. The gaps between all of the discs  32  allows the pressurized fluid traveling through the orifices  38  to effectively clean particles that may be in the grooves  32   a  of the discs  32 .  
         [0048]     Manual valves, electric valves, or other flow control devices may be used to control the fluid flow into and out of the self-cleaning filter. The electric valves (not shown) may also be controlled with a computer system and may be further automated by using a pressure differential detection system (not shown) together with the computer system and electric valves. When particles or other solids build up in the ring disc grooves  32   a  or on the outside of the ring discs  32 , the pressure difference between the inlet  16  and the outlet  18  will reach a predetermined level at which point an alarm can be activated or the computer system can automatically shut the outlet  18 , open the flushing flow  15  to the spray tube  36  to clean the filter. If a computer system is used together with a pressure differential sensing device, together with electric valves to control the flow, the entire self-cleaning filter can operate without human intervention.  
         [0049]     The following table lists the part numbers and part descriptions as used herein and in the drawings attached hereto.  
                                             Parts List                Part Number:   Description:                       A   Manual Ring Disc Filter Assembly           B   Self-Cleaning Ring Disc Filter Assembly           10   Body           12   Cover           14   Securing Ring           15   Flushing flow           16   Inlet           16a   Inlet flow           16b   Backflush flow out           18   Outlet           18a   Outlet flow           18b   Backflush flow in           20   Port (filter cover)           22   Pressure measurement port (inlet)           24   Pressure measurement port (outlet)           25   Opening for Inlet Fitting           26   Limiting collar           27   Spring           27a   Raised ring           30   Compression plate           30a   Spray tube seal           32   Ring disc           32a   Ring disc grooves           32b   Open filtrate flush space in manual filter           32c   Annular filtrate flush space between spray               tube and ring discs in self-cleaning filter           32d   Ring disc ridge           32e   Top surface of ring disc           32f   Bottom surface of ring disc           32g   Intersecting ridges           34   Spine           34a   Spine leg           34b   Spine entry taper           35   Cross member           36   Spray tube           37   o-ring seal           38   Orifice           38a   Orifice upward angle           40   Inlet fitting           40a   Seal of inlet fitting to body           40b   Bore of inlet fitting           40c   O-ring groove           41   Flow diverter           42   Backflush water inlet fitting           44a   Upward flow direction           44b   Tangential flow direction           46   Sealing ring           50   Spring compressor           50a   Spring compressor body           52   Compressor Spring           53   Post           54   Internal Spring           55   Button           56   Hydraulic compressor           56a   Hydraulic compressor body           57   Hydraulic compressor piston           58   Compression rod                      
 
         [0050]     The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size and shape of filter kit components, self-cleaning filter systems and configurations, and differing materials, as well as changes in the details of the illustrated embodiments may be made without departing from the spirt of the invention.