Abstract:
A magnetic filter removes magnetic particles from fluid communicated through the filter. The filter includes elongated, circumferentially spaced magnetic elements which capture magnetic particles entrained in the fluid. The magnetic elements must be cleaned periodically to remove the particles from the elements by moving a scraper plate from one end of the housing to the other. At the end of travel of the scraper plate, the particles are scraped upon non-magnetic end portions (which may contain residual magnetism) of the magnetic elements, from which they are flushed by fluid communicated through the inlet port out through other ports provided on the housing.

Description:
TECHNICAL FIELD 
     This invention relates to a magnetic filter for separating magnetic particles from fluids. 
     BACKGROUND OF THE INVENTION 
     Many industrial processes generate fluids in which magnetic particles are suspended. For example, motor vehicles are commonly painted by dipping the entire body into a large paint bath. Since the body is assembled by welding and the welds are sanded, many iron particles remain loosely attached to the vehicle. When the vehicle is dipped into a paint bath, these particles mix with the paint. Accordingly, it is desirable to remove the particles from the paint continuously. Similarly, many industrial machining processes use cooling fluids, such as oil, in which magnetic particles may be suspended, and it is accordingly necessary to remove these particles from the oil. 
     Centrifuges and magnetic filters have been used in the prior art to remove magnetic particles suspended in fluids. Centrifuges are effective for removing large particles, but are ineffective in removing small particles, and it is desirable in many processes that small particles be removed. Magnets and magnetic filters are effective in removing small particles, but these particles remain attached to magnets, and filters incorporating magnets for the removal of magnetic particles must be cleaned at regular intervals. However, the cleaning of magnetic filters to remove magnetic particles captured by magnets within the filter is relatively expensive, since it requires substantial manual labor, requires substantial production down time, wastes a significant quantity of the fluid, and may require expensive equipment to effect cleaning. 
     SUMMARY OF THE INVENTION 
     According to the present invention, a magnetic filter consisting of multiple elongated magnetic elements which terminate in non-magnetic end portions is provided with a scraper which can be periodically actuated to scrap the particles that have been retained on the magnet in elements onto the non-magnetic end portions. The fluid being processed flushes the particles from the end portion into a flushing chamber, from which the fluid is discharged from the magnetic filter. Accordingly, the same fluid is used to remove the particles from the magnetic filter as is being processed by the magnetic filter and no disassemble is required. Labor and down time are minimized, and the waste of the processed fluid is also minimized. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a view in perspective of a magnetic filter made pursuant to the teachings of the present invention; 
     FIG. 2 is an exploded view in perspective of the magnetic filter illustrated in FIG. 1; 
     FIGS. 3-5 are longitudinal cross-sectional views of the magnetic filter illustrated in FIGS. 1 and 2, with the scraper removing the particles captured by the magnets within the filter housing as being shown in its various operative positions; and 
     FIG. 6 is a cross-sectional view taken substantially along lines  8 — 8  of FIG.  3 . 
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings, a magnetic filter made pursuant to the present invention is generally indicated by the numeral  10 . Magnetic filter  10  includes a housing generally indicated by the numeral  12 , which includes a longitudinally extending portion  14 , and a pair of transverse end portions  16 ,  18  mounted on opposite ends of the longitudinally extending portion  14 . Each of the end portions  16 ,  18  includes an end plate  20 ,  22 , each of which is secured to opposite ends of the longitudinal extending portion  14 , and a removable cover plate  24 ,  26  each of which is secured to the corresponding end plates  20 ,  22  by appropriate fasteners  28 . 
     The housing portion  14  circumscribes multiple (in this case six) longitudinally extending, elongated, substantially parallel magnet elements  30 A-F. The magnet elements  30 A-F each include an outer housing  32  that terminates in transverse ends  34 ,  36 . Each of the transverse ends  34 ,  36  define an aperture that receives a correspondingly pin  38 ,  40  mounted on the corresponding end plates  24 ,  26  to thereby position the magnetic elements  30  A-F in their proper locations within the housing portion  14 . Each of the housings  32  enclose multiple magnetic segments which include two end segments  42 ,  44  and multiple intermediate segments  46  which extend between the end segments  42 ,  44 . The segments  42 ,  44  and  46  are maintained an axial alignment by the housing  32  of each of the magnetic elements  30 A-F. Each of the segments  42 ,  44  and  46  define a magnetic axis extending between north and south magnetic poles at opposite ends thereof, and each of the intermediate segments are installed in their corresponding housings  32  such that the north pole of one of the intermediate segments is continuous with the south pole of an adjacent segment. The housings  32  extend beyond the outer ends of the end segments  42  and  44  to define non-magnetic portions  48 ,  50  of each of the magnetic elements  30 A-F. Although the end portions  48 ,  50  are nominally non-magnetic, there will be residual magnetism in the end portions  48 ,  50 . 
     Fluid containing magnetic particles suspended therein is admitted into the housing  12  through an inlet port  54  and is discharged through an outlet port  56 . As the fluid communicates through the housing between the inlet and outlet ports, magnetic particles entrained in the fluid are captured on the surface of the magnetic elements  30  A-F. Although some of the particles will be distributed over the entire surface of the magnetic elements  30  A-F, the particles will tend to concentrate at the juncture between the north and south poles of adjacent magnetic segments  42 ,  44  and  46 . The particles must eventually be removed from the magnetic elements  30  A-F, but the frequency that they must be removed is a function of the concentration of the magnetic particles in the fluid. Prior art of the magnetic filters required disassembly of the housing  12 , removal of the magnetic elements  30 A-F, and manual removal of the magnetic particles from the elements  30 A-F. 
     According to the invention, elements  30 A-F are cleaned by a scraper plate generally indicated by the numeral  58 . Plate  58  is slideably received within housing portion  14 , and includes circumferentially spaced apertures  60 A-F, which slideably receive corresponding magnetic elements  30 A-F. Mounted within each of the apertures  60 A-F are bronze wipers  62  (FIG. 6) that frictionally engage the outer surface of magnetic elements  30 A-F to wipe the particles collected on the magnetic elements port onto one of the end portions  48  or  50  at opposite ends of the magnetic elements. Plate  58  is operated by a hydraulic piston and cylinder assembly generally indicated by the numeral  64 . Assembly  64  includes a cylinder housing  66  which includes an enlarged portion  68  defining a shoulder  70  with the smaller diameter portion thereof. A cylinder rod  72  extends from one end of the housing  66  and is connected to a double acting hydraulic cylinder (not shown) which is slideable within the housing  66  in a manner well known to those skilled in the art. Fluid fittings  74 ,  76  are connected to an appropriate source of hydraulic pressure. Hydraulic pressure is admitted into fitting  74  while fitting  76  is communicated to sump pressure to move the polar rod  72  to the left viewing the Figures, and the fitting  76  is communicated to hydraulic pressure while fitting  74  is communicated to sump pressure to move the rod  72  to the right viewing the Figures. 
     The piston and cylinder assembly  64  is installed in the housing  12  through an aperture  78  in the end plate  24 , and extends through an aperture  80  in the scraper plate  58 , and an aperture  82  in the end plate  26 . Accordingly, the hydraulic piston and cylinder assembly  64  is supported within the housing  12  coaxial with the scraper plate  58  and coaxial with the volume defined by the magnetic elements  30 A-F. The shoulder  70  is seated on the outer surface of the plate  24  to establish the proper position of the piston and cylinder assembly  64 . Accordingly, the piston rod  72 , even in its retracted position illustrated in FIGS. 2 and 3, extends beyond the end of the end plate  26  as does a portion of the housing  66  carrying the fitting  76 . The fitting  74  is also exterior of the housing, being located on the enlarged portion of  68 . An appropriate fastener  84  secures the piston rod  72  to a push/pull plate  86 . Push/pull plate  86  is secured to scraper plate  58  by rods  88 , which are secured to the push/pull plate  86  by appropriate fasteners and extend through corresponding apertures  90  in end plate  26  and are secured to the scraper plate  58  by fasteners  92 . Flushing chambers  94 ,  96  are defined within each of the end plates  20 ,  22  and are provided with drain lines  98 ,  100 . 
     When it is desired to clean the magnetic particles off of the surfaces of the magnetic elements  30 A-F, and assuming that the scraper plate  58  is in the position illustrated in FIG. 3, fluid is admitted into the hydraulic cylinder assembly  64  through fitting  74 , thereby driving the piston (not shown) within the cylinder  66  to the left viewing the Figures, and forcing the piston rod  72  to the left viewing FIGS. 3-5. As illustrated in FIG. 4, as the scraper plate  58  travels to the left viewing the Figures, the magnetic particles will be swept to the left viewing the Figures with most of the particles remaining on the outer surface of the magnetic element  38  due to the magnetic attraction of the magnetic segments  42 - 46 . As plate  58  is forced into the FIG. 5 position, which is the maximum travel position to the left viewing the Figures, the particles are scraped onto the non-magnetic end portions  50  of the magnetic elements  30 A-F. At this time, the outlet port  56  is closed off, drain line  100  is opened, and fluid is continued to be pumped through inlet port  54 . A small clearance exists between the outer circumferential surface of the scraper plate  58  and the inner surface of the housing portion  14 . Accordingly, fluid entering the inlet  54 , since it is blocked from being discharged through outlet port  56 , communicates through the small gap or clearance between the scraper plate  58  and the housing  14 . Accordingly, particles accumulated on the non-magnetic end portion  50  of the magnetic elements  30 A-F will be flushed off of the magnetic elements and into the flushing chamber  96 . Particles in flushing chamber  96  are discharged through drain line  100 , into appropriate containers either for further processing or for discard. 
     The scraper plate  58  rod  72 , push/pull plate  86  and the rods  88  remain in the position illustrated in FIG. 5 while the outlet port  56  is reopened and fluid is again communicated through the housing  14 . When a quantity of magnetic particles are again accumulated on the magnetic elements  30 A-F such that cleaning is again required, hydraulic fluid under pressure is admitted through fitting  76  into the cylinder  66 , thereby driving the double acting piston (not shown) to the right, thereby also forcing the scraper plate  58  to the right. When the scraper plate is returned to the FIG. 3 position, the outlet port  56  is closed off and drain line  98  is opened to permit fluid to communicate around the scraper plate  58 , to thereby flush the magnetic particles off of the non-magnetic end portions  48  of the magnetic elements  30  A-F and into the flushing chamber  94 . The fluid in flushing chamber  94  is discharged through drain line  98  and is captured to be either disposed of or further processed. 
     Fluid lines  102 ,  104  may be provided to communicate fluid directly into the portion of the housing between the scraper plate  58  and the end plate  24  or  26 , through which the non-magnetic portions  48  or  50  of the magnetic elements  30 A-F extend. This fluid communicated through fluid lines  102 ,  104  flushes the particles from the end portions  48  or  50  of the magnetic elements  30 A-F and into corresponding flushing chambers  94 ,  96 , from which the fluid is discharged as described above through drain lines  98  and  100 . If the lines  102 ,  104  are used to flush magnetic particles, the inlet port  54  and outlet  56  remain open, permitting continued processing of fluid in which the magnetic particles are entrained even while particles cleaned from the magnetic elements  30  A-F are being flushed from the filter  10 .