US3543542A - Self-cleaning filter - Google Patents

Description

- Dec; 1, 1970' JQB'OCHA'N SELF-CLEANING FILTER Filed Jan. 29, l969 3 Sheets-Sheet 1 INVENTOR. J'OHN BOCHAN HlS ATTORNEY FDGJ Dec. 1, 1970' J. BOCHAN SELF-CLEANING FILTER 5 Sheets-Sheet 2 Filed Jan. 29, 1969 INVENTOR. J'OHN BOCHAN H15 ATTORNEY Dec. 1, 1970 BOCHAN 3,543,542

SELF-CLEANING FILTER Filed Jan. 29, 1969 5 Sheets-Sheet S I03 INVENTOR.

J'OHN BOCHAN HIS ATTORNEY United States Patent O 3,543,542 SELF-CLEANING FILTER John Bochan, Louisville, Ky., assignor to General Electric Company, a corporation of New York Filed Jan. 29, 1969, Ser. No. 794,891 Int. Cl. D06f 29/00 US. Cl. 68-18 13 Claims ABSTRACT OF THE DISCLOSURE A self-cleaning filter assembly for removing impurities from a fluid flow is provided having a housing defining a chamber therein and having inlet and outlet means comprising a centrally positioned opening in the bottom portion of the housing and at least one opening formed else where in the housing. A plurality of circular discs are disposed one above the other in stacked relationship within the chamber, the uppermost of the discs being imperforate, the remainder of the discs having an aperture formed centrally therein. Spacing means separate each disc from adjacent discs, and the cross-section of the chamber is sufficiently large to permit the discs to stack therein with edges randomly unaligned and randomly contacting the housing. Impurities trapped along the edges of the stacked discs during fluid discharge from the chamber through the bottom opening are prevented, by the unaligned edges of the stacked discs, from forming a solid continuous blanket therealong. By preventing such a blanket formation, the discs are able to separate and thereby release the impurities during fluid discharge from the chamber through the other opening.

BACKGROUND OF THE INVENTION This invention relates generally to an improved selfcleaning filter for removing lint and other foreign materials from the recirculating flow of fluid passing through fabrics in the washing and rinsing operations of an automatic clothes washer.

In domestic automatic washing machines, clothes are placed within a container such as a blanket supported within an outer tub. Fluid is added to the clothes container and a means such as an agitator is employed to agitate the washing fluid to wash the clothes and carry away the foreign materials which have soiled the clothes. At the end of the washing operation, the washing fluid is drained whereupon a series of rinses may be utilized followed by centrifugal fluid extraction through high speed rotation of the washing basket. During the washing and rinsing processes, the washing fluid becomes laden with foreign materials removed from the clothes, and with particles of lint or the like which are loosened and removed from the fabrics by the fluid. These impurities deter the efficient action of the cleaning fluid and may redeposit themselves on the clothes when the wash or rinse water is drained away, or when the clothes are spun dry.

It is, therefore, highly desirable to provide a means for removing the lint and foreign particles from the water during the Washing and rinsing operations. Filters of various configurations have been provided for removing such impurities in previous machines, but have not been wholly effective either because they were not self-cleaning in nature or because the self-cleaning provision thereof was subject to temporary or permanent clogging. Where such filters are not self-cleaning in nature, proper operation is dependent on periodic maintenance of the filter by the operator. Such periodic attention is bothersome to the operator and is subject to neglect, resulting in clogging of the filter by impurities which may seriously impair the recirculation flow and thereby reduce washing quality.

3,543,542 Patented Dec. 1, 1970 Previously known self-cleaning filters, on the other hand, have been highly subject to clogging. Temporary clogging, which may be relieved during the self-cleaning cycle, commonly occurs in such filters due to insufiicient filtering capacity. Permanent clogging is also common where the filter construction is such as to provide internal portions of sufliciently small perimeter to permit thread-like impurities to wrap completely therearound and become entangled thereupon.

It is therefore an object of my invention to provide a new and improved self-cleaning filter assembly for removing solid impurities from a fluid stream.

Another object is to provide a compact self-cleaning filter assembly having a large filtering capacity to minimize temporary clogging.

Another object is to provide a self-cleaning filter assembly with internal elements so designed as to minimize permanent clogging thereof by thread-like materials wrapping themselves around and entangling upon parts of limited perimeter.

A further object of the invention is to provide such an improved filter assembly in an automatic clothes washer to clean lint and foreign particles from the washing fluid during the washing and/or rinsing operation and to release them to drain thereafter.

SUMMARY OF THE INVENTION Briefly stated, in accordance with one aspect of the present invention, there is provided a self-cleaning filter assembly for removing solid impurities from a fluid stream comprising a housing defining a chamber therein, and inlet and outlet means, for admitting fluid to the chamber and for discharging fluid therefrom comprising a first opening positioned within the bottom portion of the housing, and additional opening means formed within a portion of the housing other than the bottom portion. A plurality of discs are disposed one above the other in stacked relationship within the chamber, the uppermost of the stacked discs being imperforate. At least one substantially centrally disposed aperture is formed in each of the discs other than the uppermost disc, and spacing means are provided to separate each of the discs from adjacent discs. The chamber is of sufficient size to accommodate the stacked discs therein with the edges of the discs unaligned. The fluid stream passes through the spaces between the stacked discs and then through the apertures in the discs to flow from the opening means to the first opening. By this arrangement, impurities are removed from the fluid stream at the outer edges of the discs to filter the stream, and the unalignment of the outer edges of the discs acts to prevent the removed impurities from forming a continuous blanket along the edges. The discs are thereby enabled to separate from the stacked relationship and the impurity formation to break up when fluid is passed through the chamber and discharged by means other than the first opening for cleaning the filter assembly.

BRIEF DESCRIPTION OF THE DRAWINGS While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention, it is believed the invention will be better understood from the following description of the preferred embodiments taken in connection with the accompanying drawings, in which:

FIG. 1 is a partial, schematic, elevational view of a clothes washing machine including one embodiment of the present invention;

FIG. 2 is a sectional view of the filter assembly of FIG. 1 showing my device in the filtering mode;

FIG. 3 is a view taken along line 33 of FIG. 1;

FIG. 4 is a sectional view similar to FIG. 2 showing my device in the self-cleaning mode;

FIG. is an enlarged partial sectional view of the discs used in the embodiment of FIG. 1;

FIG. 6 is a partial plan view of one of the discs of FIG. 5;

FIG. 7 is a sectional view of another embodiment of my device; and

FIG. 8 is a plan view of the embodiment of FIG. 7, the view being partly broken away to show details.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, and initially to FIG. 1 thereof, there is illustrated an agitator-type vertical axis automatic clothes washer 10. The washer 10 normally includes a suitable appearance and protective outer cabinet which, in the interest of clarity, has been omitted from the drawings. The washer may include a rigidly mounted imperforate tub 11 having a perforate washing basket or container 12 rotatably supported therein for washing and rinsing clothes therein and for centrifugally extracting liquid therefrom. At the center of the basket 12 there is provided an agitator 13 which includes a center post 14 having a plurality of curved water circulating vanes 15 joined at the lower end to form an outwardly flared skirt 16. Normally a resilient gasket (not shown) is provided between the upper edge of tub 11 and the appearance cabinet to prevent moisture from escaping into the space between the tub and cabinet.

Both the washing basket 12 and the agitator 13 are rotatably mounted. The basket is mounted on a flange 17 of a hub 18 and the agitator 13 is mounted on a shaft 19 which extends upwardly through the hub 18 and through the center post 14 and is secured to the agitator so as to drive it. During one possible cycle of operation of the washer 10, liquid is introduced into tub 11 and basket 12, and the agitator is oscillated around its axis to wash the clothes within the basket. After a predetermined period of this washing action, basket 12 is rotated at high speed to centrifugally extract the washing liquid from the fabrics. Following this extraction operation, a supply of clean liquid is introduced into the basket for rinsing the fabrics, and the agitator is again oscillated. Finally, the basket is once more rotated at high speed to extract the rinse liquid.

The basket 12 and the agitator 13 may be driven by any suitable means. By way of example, I have shown them as driven from a reversible motor 20 through a drive mechanism including a clutch 21 mounted on the motor shaft. A suitable belt 22 transmits power from clutch 21 to a transmission assembly 23 through a pulley 24. Thus, depending upon the direction of motor rotation, the pulley 24 of transmission 23 is driven in opposite directions. The transmission 23 is so arranged that it supports and drives both the agitator drive shaft 19 and the basket mounting hub 18. When motor 20 is rotated in one direction, the transmission causes agitator 13 to oscillate and when motor 20 is driven in the opposite direction, the transmission rotates the washing basket 12 and the agitator 13 together at high speed for centrifugal fluid extraction. While the specific type of transmission used does not form a part of the present invention, reference is made to U.S. Pat. No. 2,844,225 issued July 22, 1958 to Mr. James R. Hubbard et al. and assigned to the assignee of the instant invention. That patent discloses in detail the structural characteristics of the transmission assembly suitable for use in the illustrated machine.

In addition to operating the transmission 23 as described, motor 20 also provides a direct drive through a flexible coupling 25 to a pump structure 26 which includes two separate pumping units 27 and 28 which are operated simultaneously in the same direction by motor 20. Pump unit 27 has an inlet connected by a conduit 29 to a filter assembly 30, which is in turn connected by a conduit 31 to an opening 32 formed in the lower most part of the tub 11, and an Outlet connected by a conduit 33 to a suitable 4 drain (not shown). Pump unit 28 has an inlet connected by a conduit 34 to filter 30, and an outlet connected by a conduit 35 to a nozzle 36 positioned to discharge into basket 12. With this structure, when the motor is operated so as to provide agitation, pump 28 draws liquid in through conduit 34, filter 30, and conduit 31 from tub 11 and discharges it through conduit 35 into basket 12. Conversely, when the motor is reversed so as to rotate the basket 12 and agitator 13 together at high speed to centrifugally extract fluid from fabrics in the basket, pump 27 will draw liquid in from conduit 29, filter 30, and

conduit 31 from tub 11 and discharge it through conduit 33 to drain. Each of the pump units is substantially inoperative in the direction of rotation in which it is not used.

In order to accommodate any vibrational movement which occurs between transmission 23 and tub 11, which also represents vibrational movement between basket 12 and tub 11, without any danger of fluid leakage between them, the stationary tub 11 is joined to the upper part of transmission 22 by a flexible boot member 37. A member of this type is described and claimed in US. Pat. No. 2,959,966 issued Nov. 15, 1960 to Mr. John Bochan and assigned to the assignee of the instant invention.

Hot and cold water may be supplied to the machine through conduits 38 and 39 which are adapted to be connected respectively to sources of hot and cold water (not shown). Conduits 38 and 39 extend into a conventional mixing valve structure 40 having solenoids 41 and 42 and being connected to a hose 43. In a conventional manner selective or concurrent energization of solenoids 41 and 42 will provide the passage of hot, cold or warm water from the mixing valve 40 through the hose 43. As is increasingly required by plumbing codes to prevent contamination of the household water supply, a vacuum break 44 is provided for connection to hose 43 and comprises an inlet 45, an outlet 46, and an opening 47 to the machine interior between inlet 45 and outlet 46. A nozzle 48 is connected to outlet 46 and is positioned to discharge water into basket 12. By this arrangement, suds and liquid in the vicinty of a nozzle 48 will not be drawn inwardly through nozzle 48 and into the household water supply if the household water supply should experience a short duration vacuum when valve structure 40 is supplying water to the machine.

It will be understood that, while the description of the machine thus far excludes a substantial amount of detail relating to the drive, and does not show all the valves and particular controls normally provided on modern domestic clothes washing machines, the elimination and simplification of these items is primarily for the purpose of permitting a clear explanation of the inventive concept set forth below. It will be recognized that the omitted details are conventional items included in virtually all automatic clothes washing machines, whose structure and positioning is well known to those skilled in the art.

In automatic washing machines it is advantageous for the stream of fluid admitted to the basket 12 from nozzle 36 be free of lint and foreign particles which may otherwise be deposited upon the clothes within basket 12. For this purpose, filter assembly 30 is connected within the recirculation flow system defined by conduit 31, conduit 34, pump unit 28, and conduit 35. It is also desirable that filter 30 be self-cleaning in nature. For this purpose, filter assembly is connected within the drain system defined by conduit 31, conduit 29, pump unit 27 and conduit 33 whereby fluid being drained from tub 11 may be used to carry impurities deposited within filter 30 to a drain or sewer.

Referring now, more particularly, to FIGS. 2-4 wherein one embodiment of my device is illustrated, it will be seen that filter assembly 30 comprises a housing 49 with a plurality of walls or wall portions defining 'a chamber 50' therein. Included among the walls or wall portions of housing 49 are a bottom wall 51, a substantially vertical side wall 52, and a top wall 53. Inlet and outlet means are provided for admitting fluid to chamber 50 and for discharging fluid therefrom comprising an outlet opening 54 positioned substantially centrally within bottom wall 51, an outlet opening 55 positioned substantially centrally within top wall 53, and an inlet opening 56 in vertical side wall 52. As may be best seen in FIG. 3, in cross section vertical side wall 52 forms a substantially equilateral hexagon, and inlet opening 56 is directed substantially tangentially to chamber 50 and parallel to the adjacent equilateral side 57.

Associated with each of the aforedescribed openings 54, 55 and 56 are connection means adapted to connect filter 30 with the aforementioned conduits 29, 31 and 34. Associated with outlet opening 54 is a connection means 58 comprising an L-shaped member 59 secured at its upper end 60 to an annular projection 61 depending from housing 49, and having an elongated portion 62 of uniform diameter formed on the lower end terminating in an annular locking ramp 63. By this arrangement, connection means 58 is particularly adapted for use with a flexible conduit such as plastic tubing which may be forced over the annular locking ramp 63 and secured to elongated portion 62 by a suitable adhesive or by a suitable clamp. When used in association with the automatic washer of FIG. 1, connection means 58 connects with conduit 34.

Similarly positioned atop housing 49 is a connection means 64 associated with outlet opening 55 for connection to conduit 29 of FIG. 1. Connection means 64 comprises an L-shaped member 65 identical to L-shaped member 59, and is secured at its lower end 66 to an annular projection 67 extending from housing 49. As with L-shaped member 59, member 65 has an elongated portion 68 of uniform diameter terminating in an annular locking ramp 69 particularly adapted for connection with a flexible conduit.

Associated with tangential inlet opening 56 is a connection means 70 comprising an L-shaped member 71 integral at its upper end 72 with bottom wall 51 of housing 49, and communicating with a passageway 73 formed by an outward extension 74 of vertical side wall 52. Th lower end of L-shaped member 71 has an elongated portion 75 terminating in an annular locking ramp 76 adapted for connection with conduit 31 of FIG. 1.

At this point it will be apparent that the entire outer structure of my filter assembly comprises only four sepa rate pieces, namely an upper housing member 77 comprising vertical side wall 52, top wall 53 and outward extension 74, a lower housing member 78 comprising L- shaped member 71 and bottom wall 51, and two identical L-shaped members 59 and 65. Each of these four outer structural members is of such configuration as to readily permit formation thereof by injection molding or other suitable molding techniques, and in this respect provides a simple and inexpensive structure capable of being produced from a Wide variety of substantially rigid materials.

Sandwiched between L-shaped member 59 and annular projection 61 to prevent fluid leakage therebetween is a gasket 79. Integrally formed with gasket 79 and connected by a flexible hinge thereto is a means for selectively opening and closing outlet opening 54, comprising a resilient flap portion 80. Flap portion 80 is adapted to cooperate with an annular lip 81 formed within annular projection 61 to close opening 54 when the pressure within chamber 50 is less than that within L-shaped member 59, and adapted to open the outlet opening 54 when the pressure within L-shaped member 59 is less than the pressure within chamber 50.

Similarly sandwiched between L-shaped member 65 and annular projection 67 to prevent fluid leakage therebetween in a gasket 82. Integrally formed with gasket 82 for selectively opening and closing outlet opening 55 is a resilient flap portion 83. Flap portion 83 is adapted to cooperate with an annular lip 84 formed within annular projection 67 to close opening 55 when the pressure within chamber 50 is less than that within L-shaped member 6 65, and adapted to open the outlet opening 55 when the pressure within L-shaped member 65 is less than the pressure within chamber 50.

By the aforedescribed arrangement of means for selectively opening and closing outlet openings 54 and 55, it will be seen that when the pressure is reduced within lower L-shaped member 59 by means of pump unit 28, flap will open permitting the pressure within chamber 50 to be similarly reduced causing flap 83 to close opening 55, whereby a suction force will be exerted on the fluid in communication with tangential inlet 56. Similarly, 'when the pressure is reduced within upper L-shape'd member 65 by pump unit 27, flap 83 will open permitting the pressure within chamber 50 to be reduced causing flap 80 to, close opening 54, whereby a suction force will be exerted on the fluid in communication with tangential inlet 56. Thus depending on the direction of rotation of pump structure 26 by reversible motor 20, fluid will enter tangential inlet 56 of filter 30 and discharge either to lower outlet opening 54 or to upper outlet opening 55.

Having described the outer structure of my filter assembly and the means whereby fluid is admitted to, and discharged from, the filter chamber, I now turn to a description of the filter mechanism disposed within the filter chamber, which principally comprises a plurality of discs 85 disposed one above the other in stacked relationship. Discs 85 are substantially circular and of substantially uniform diameter. Spacing means are provided to separate each of the discs from adjacent discs, comprising projections 86 depending from the lower surfaces of the discs. The uppermost disc 87 is imperforate while the remaining discs each have a centrally disposed aperture 88 formed therein substantially in alignment with lower outlet opening 54.

During the filtering mode of operation, fluid enters chamber 50 from inlet opening 56 and flows through the spaces between discs 85 and through the apertures 88 in the discs and exits chamber 50 through lower outlet opening 54. Chamber 50 is of sufficient size to permit stacking of discs 85 therein with the peripheral edges of the discs randomly unaligned and randomly contacting the vertical housing wall as shown in FIG. 2. By this arrangement of discs 85 randomly contacting housing wall 52, impurities trapped along the edges of the stacked discs, are prevented from forming a solid or continuous blanket therealong. By preventing, in this manner, the formation of a solid wrapping of impurity deposit about the filter structure, my device achieves a significant advance over prior art configurations enabling the filter to readily break up the impurity deposit. The impurity deposit thereby in no way hinders the self-cleaning operation and tends to discharge from the filter in small sectors posing much less of a clogging threat to the machine discharge conduits than would a larger unitary impurity deposit.

Referring now more particularly to FIGS. 5 and 6 wherein the construction of the aforementioned discs 85 is illustrated in greater detail, it will be seen that projections 86 are formed by pressing a portion of the flat planar disc surface 89 downwardly thereby forming a small and insignificant cavity 90 above each projection. As the length and width dimensions of cavity 90 are less than the length and width dimensions of disc projections 86, the projection of one disc are prevented from entering the cavity of the lower disc. The cavities, therefore, do not alfect the operation of each of the upper planar disc surfaces 89 as a supporting surface for the adjacent discs disposed thereabove. The projections 86 are disposed on each of the discs at a sufliciently small diameter concentric with the disc edge so as to support the discs when a stacked relationship having randomly unaligned edges is formed.

Another feature of my invention is the large perimeter which my design provides on all surfaces within chamber 50 which are exposed to the impurity laden fluid flow. A serious drawback of prior art self-cleaning filters has been the necessity of incorporating within the filter chamber one or more elements having a perimeter or circumference small enough to permit thread-like impurities or lint formations to wrap completely around these elements with subsequent entangling of the end portions of the thread-like impurities. Such wrapping and entangling about small perimeter element has been a serious drawback. of many prior art filter designs as the impurity deposits so formed are practically impossible to remove in any fashion other than cutting them loose with a sharpened blade. It is therefore a feature of my design that the elements which form the filtering medium per se are provided with large cross-sectional perimeters. For example, as seen in FIG. 5, the discs 85 each have a minimum pe rimeter defined by twice the disc thickness plus twice the distance 91 between central aperture 88 and the outer peripheral disc edge. The distance 91 is selected to be of such length that the resulting minimum perimeter is greater than the longest thread-like impurity likely to enter the filter structure. In this manner, permanent clogging of my filter is guarded against.

A further feature of my design is in its compactness while providing a sufficiently large filtering area to prevent temporatry clogging, as occurs in prior art devices having insufficient filtering area to handle fluids having a high impurity content. The entire circumferential area of the discs 85 forms the filtering area of my device, and as will be readily apparent, the outer structure of the filter housing is not of significantly greater size than the filtering area it houses, thereby providing a compact assembly. Furthermore, depending on the filtering requirement of the particular system in which my filter is employed, more or less filtering area may be readily added or subtracted from my device by adding or subtracting discs 85 and correspondingly adjusting the length of vertical side wall 52. In washing machine application, a filter having suflicient filter area to prevent clogging has been constructed using forty-six discs formed of 0.020 inch thick thermally and hydrologically stable thermoplastic, the discs being approximately three and one half inches in diameter and each having a single one and one quarter inch central aperture formed therein.

In operation, my device does not rely entirely on the separation between the discs to perform the filtering function. Such separation between discs 85 as provided by projections 86 is ideally made greater than the size of the smallest impurity particles to be removed from the recirculation flow. By this arrangement, an impurity buildup is begun on the periphery of discs 85, starting with larger lint and impurity particles and progressing to smaller particles, whereby the impurities themselves readily become the primary filter medium. A disc separation of 0.009 inch has been found acceptable for such operation in connection with an automatic clothes washer.

In the preferred form of my invention, as has been described in conjunction with FIGS. 24, discs 85 are adapted to rotate during the self-cleaning operation. To augment rotation during self-cleaning, a plurality of vanes 92 are formed integral with the top surface of uppermost disc 87 and integral with the bottom surface of lowermost disc 93. During self-cleaning, as shown in FIG. 4, discs 85 separate from each other and rotate randomly under the influence of fluid entering through tangential inlet 56. In separating, the discs rise upwardly toward top wall 53 and outlet opening 55. In order to prevent the discs from turning on end and wedging in chamber 50, and to prevent the vanes 92 formed on uppermost disc 87 from contacting top wall 53, a pivotal means 94 is positioned within the upper portion of chamber 50, depending from top wall 53, to engage uppermost disc 87 during the self-cleaning operation. Pivotal means 94 includes a downwardly convex spherical sector 95 supported by a member 96 integral with top wall 50. Spherical sector 95, as may be seen in FIG. 4, serves as a pivotal 8 bearing surface for uppermost disc 87 to pivot about in a random to and fro, tilt and toss fashion.

In somewhat analogous fashion, provision is made heneath lowermost disc 93 to permit the vanes 92 formed integral therewith to rotate without contacting bottom wall 51. In the embodiment of FIG. 2, such provision takes the form of an upstanding circular wall portion 97 formed integral with bottom wall 51 defining an inner annular groove 98 into which lowermost disc vanes 92 may depend without contacting bottom wall 51.

To assure no entangling of thread-like impurities about vanes 92, the vanes are designed With substantially wide surfaces. Furthermore, the edges of vanes 92 are not parallel to each other thereby forming a tapered vane configuration which will permit impurities to slide off the ends thereof if such impurities should become deposited thereon. To further discourage thread-like impurity deposits within chamber 50, spherical sector 95 and supporting member 96 are of sufficiently large cross section as to provide a minimum periphery greater than the longest therad-like impurity likely to enter the filter structure.

To further augment disc rotation, it will be ssen in FIGS. 2-4 that the tangential inlet opening 56 extends from bottom wall 51 upwardly to a point on vertcial side Wall 52 above which discs may rise. By this arrangement, the tangential fluid inflow is directed toward the peripheral edges of all the discs 85 tending to rotate all of the discs rather than only a limited number thereof.

It should be understood that in the operation of my device, the discs 85 are caused to rotate only during the self-cleaning operation, and not during the filtering func tion. Discs 85 are released for rotation only when they are caused to rise upwardly from their normally stacked relationship under the infuence of fluid being discharged from chamber 50 through upper outlet opening 55 as a result of the operation of pump unit 27. Due to frictional forces, no rotation of discs 85 is experienced when the discs are drawn tightly downwardly into stacked relationship under the influence of fluid being discharged from chamber 50 through lower outlet opening 54 as a result of the operation of pump unit 28.

As has been previously explained, during the filtering function, discs 85 assume a stacked relationship with the edges of the discs randomly unaligned and randomly contacting vertical side wall 52. The outer edges of discs 85 when in such stacked relationship approximately define a cylindrical filtering unit of radius somewhat greater than that of the individual discs 85. In order to assure proper vertical fluid flow between this filtering unit and vertical side wall 52, it is within the scope of my invention to incorporate one or more substantially vertically oriented protrusions in vertical side wall 52 to provide one or more unobstructed vertical flow paths Within chamber 50. By the term protrusion, I means such an outward extension of vertical side wall 52 as will provide a vertical flow channel that will not be obstructed by the filtering unit comprising the randomly unaligned stack of discs 85. In the form of my invention as shown in FIG. 3, such protrusions simply comprise the regions of juncture 99 of the equilateral sides of vertical side wall 52. Such regions of juncture 99 provide vertical flow channels that cannot be obstructed by discs 85.

Having described in detail the structural characteristics of one form of my filter assembly, I turn now to the operation of the aforedescribed embodiment in conjunction with the washer 10 of FIG. 1. During the washing cycle wherein clothes and Washing fluid have been added to tub 11 and basket 12, agitator 13 is caused to oscillate by transmission assembly 23 driven in one direction by motor 20. The washing fluid becomes laden with foreign materials or impurities which have soiled the clothes, and with particles of lint or the like which are loosened and removed from the fabrics by the cleaning fluid. During the washing cycle, such impurity-laden fluid is withdrawn from tub 11 through conduit 31 under the action of pump structure 26 and pump unit 28 in particular. With pump unit 28 in operation, flap 80 will open and flap 83 will close as previously explained, whereby fluid will enter filter assembly 30 through inlet 56 and discharge through lower outlet opening 54 for return to washing basket 12 through nozzle 36. And, as has been explained, under the influence of fluid flowing through chamber 50 toward outlet opening 54, discs 85 are drawn tightly downwardly into stacked relationship whereupon the edges thereof act as a weir or filter surface to retain solid impurities from exiting through opening 54.

Subsequent to the washing cycle wherein filter 50 has formed a significant deposit of impurities along the edges of discs 85, motor 20 is reversed whereby pump structure 26 is driven in reverse direction and pump unit 27 alone becomes operative. With this arrangement, fluid is withdrawn from tub 11 through conduit 31, and is caused to enter filter 30 through tangential inlet 56. As previously explained, operation of pump unit 27 will cause flap 80 to close and flap 83 to open, whereupon the influence of fluid flowing toward upper outlet opening 55 will cause discs 85 to rise and separate from each other within chamber 50, thereby freeing themselves from the frictional forces which prevented their rotation while pumping unit 28 was in operation. As discs 85 separate and each disc assumes a mode of random rotation, the impurity formation is released from the edges of the discs and is broken up and carried to the drain or sewer along with the cleaning fluid. As the randomly unaligned stacked disc arrangement prevented the impurities from forming a solid blanket along the edges of the discs during the filtering operation, the impurity formation readily breaks up and the discs are readily permitted to separate and free themselves from the impurity formation.

Referring now more particularly to FIGS. 7 and 8, another form of my invention will be described which differs from the aforedescribed embodiment principally in that no provision is made for rotation of the discs during the self-cleaning operation. In this embodiment, the filter assembly 100 comprises a housing 101 with a plurality of walls or wall portions defining a chamber 102 therein. Included among the walls or wall portions of housing 101 are a bottom wall 103, a substantially vertical side wall 104, and a top wall 105. Inlet and outlet means are provided for admitting fluid to chamber 102 and for discharging fluid therefrom comprising a lower opening 106 positioned substantially centrally within bottom wall 103 and an upper opening 107 positioned substantially centrally within top wall 105. As may be best seen in FIG. 8, in cross section vertical side wall 104 is substantially circular with the exception of a plurality of vertically oriented protrusions 108 formed therein to facilitate vertical fluid flow within chamber 102.

The outer filter structure of this embodiment is seen to comprise only two separate pieces, namely an upper housing member 109 comprising vertical side wall 104, top wall 105 and suitable connection means 110 for connection to a conduit (not shown), and a lower housing member 111 comprising bottom wall 103 and suitable connection means 112 for connection to another conduit (not shown). As such the outer structure is simple in design and may be readily formed by such techniques as injection molding.

Disposed within chamber 102 are a plurality of discs 113 which, ideally, are constructed exactly as discs 85 previously described in detail in conjunction with FIGS. and 6. Uppermost disc 114 is imperforate, while the remainder of the discs 113 have an aperture 115 formed therein substantially in alignment with the lower opening 106. As with discs 85 of FIGS. 5 and 6, discs 113 are provided with spacing means comprising projections 116 depending from the lower surface of each of the discs.

In similar fashion to chamber 50 of filter assembly 30,

chamber 102 of filter is of such cross section as to permit stacking of discs 113 therein with the peripheral edges of the discs randomly unaligned and randomly contacting the vertical side wall 104. By this arrangement, impurities trapped along the edges of the stacked discs are prevented from forming a solid or continuous blanket which would impede the separation of the discs and the breaking up of the impurity deposit during self-cleaning. Formed within chamber 102 and depending from top wall are a plurality of projecting portions 117 designed to space uppermost disc 114 downwardly from top wall 105 during self-cleaning when discs 113 separate.

In operation, the embodiment of FIGS. 7 and 8 will be seen to perform a filtering function when fluid enters upper opening 107 and strikes uppermost disc 114 forcing the discs into a tightly stacked relationship whereby fluid flows through the interstices between the discs and down through the central apertures thereof to discharge from lower opening 106. Self-cleaning takes place by a reversal of fluid direction or back-flow of fluid through lower opening 106 whereupon fluid striking imperforate uppermost disc 114 causes upward movement thereof toward projection portions 117 which limit the travel of uppermost disc 114. Under the influence of fluid entering lower opening 106 and discharging through upper opening 107, discs 113 separate and bob about in chamber 102 causing the impurity formation about the edges of discs 113 to break up and discharge through upper opening 107.

The embodiment of FIGS. 7 and 8, may be incorporated for use in automatic washing machines by providing such a conventional valve and conduit network as is required to incorporate the filter within the recirculation flow system for filtering and within the drain system for self cleaning.

As was previously mentioned, my filter assembly is particularly adapted for use in automatic clothes washers wherein it is desirable to provide a means for cleaning lint and foreign particles from the cleaning fluid during the washing operation, which means will not be subject to the problems of temporary or permanent clogging and which will automatically release the impurities trapped during the washing operation for discharge to a drain or sewer during a subsequent operation.

From the foregoing description it should now be apparent that the present invention, by providing a stacked arrangement of discs having unaligned edges combined with a large minimum perimeter on all internal filtering elements will successfully overcome the problem of clogging and in this respect represents a significant improvement in filter assemblies.

As will be evident from the foregoing description, certain aspects of the invention are not limited to the particular details of the construction of the examples illustrated, and it is contemplated that various other modifications or applications will occur to those skilled in the art. It is therefore intended to cover such modifications and applications as do not depart from the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A self-cleaning filter assembly for removing solid impurities from a fluid stream comprising:

a housing defining a chamber therein;

inlet and outlet means for admitting fluid to said chamber and for discharging fluid therefrom comprising a first opening positioned within the bottom portion of said housing and additional opening means formed within a portion of said housing other than said bottom portion;

a plurality of discs disposed one above the other in stacked relationship within said chamber;

at least one substantially centrally disposed aperture formed in each of said discs other than said uppermost disc, and said uppermost disc being imperforate;

spacing means to separate each of said discs from adjacent discs; and

said chamber being of sufl'icient size to accommodate the stacked discs therein with the peripheral edges thereof unaligned;

said fluid stream passing through the spaces between said stacked discs and then through said apertures in said discs to flow from said opening means to said first opening, whereby impurities are removed from said fluid stream at the outer edges of said discs to filter said stream, the unalignment of said outer edges of said discs acting to prevent the removed impurities from forming a continuous blanket along said edges thereby enabling said discs to separate from said stacked relationship and the impurity formation to break up when fluid is passed through said chamber and discharged by means other than said first opening for cleaning said filter assembly.

2. The filter assembly of claim 1 wherein:

said housing comprises a plurality of walls including a bottom wall, substantially vertical side wall, and a top wall;

said first opening is positioned substantially centrally within said bottom wall; and

said additional opening means comprises an opening positioned within said top wall. 3. The filter assembly of claim 1 wherein said discs are substantially circular and of substantially uniform diameter, and said spacing means extend from at least alternate ones of said discs.

4. The filter assembly of claim 3 wherein said housing comprises a plurality of walls including a bottom wall, a substantially vertical side wall and a top wall, said substantially vertical side wall includes at least one substantially vertically oriented protrusion to augment vertical fluid flow along said peripheral edges of said discs and said side wall.

5. A self-cleaning filter assembly for removing solid impurities from a fluid stream comprising: a housing defining a chamber therein; said housing comprising a plurality of Walls including a bottom wall, a substantially vertical side wall, and a top wall;

inlet and outlet means for admitting fluid to said chamber and for discharging fluid therefrom comprising a first opening positioned within said bottom wall, at least one opening positioned within said side wall, and additional opening means comprising an opening positioned within said top wall;

a plurality of discs disposed one above the other in stacked relationship within said chamber;

at least one substantially centrally disposed aperture formed in each of said discs other than said uppermost disc, and said uppermost disc being imperforate;

spacing means to separate each of said discs from adjacent discs;

said chamber being of sufficient size to accommodate the stacked discs therein with the peripheral edges thereof unaligned; and

said at least one opening in said side wall comprising at least one opening directed substantially tangentially to said chamber;

said fluid stream passing through the spaces between said stacked discs and then through said apertures in said discs to flow from said opening in said side wall to said first opening, whereby impurities are removed from said fluid stream at the outer edges of said discs to filter said stream, the unalignment of said outer edges of said discs acting to prevent the removed impurities from forming a continuous blanket along said edges thereby enabling said discs to separate from said stacked relationship and the impurity formation to break up when fluid enters said chamber through said at least one opening directed substantially tangentially to said chamber tend- 12 ing to rotate said discs as fluid is passed through said chamber and discharged from said opening in said top wall for cleaning said filter assembly.

6. The filter assembly of claim 5 wherein said vertical side wall is substantially equilateral polygonal in cross section and said tangentially directed opening is directed parallel to the adjacent one of the equilateral sides thereof.

7. The filter assembly of claim 5 wherein said opening in said top wall is substantially centrally positioned within said top wall, said opening in said bottom wall is substantially centrally positioned within said bottom wall, and additionally including means for selectively opening and closing said centrally positioned top wall opening and said centrally positioned bottom wall opening, whereby one of said centrally positioned openings may be opened while the other is closed, permitting fluid admission to said chamber from said tangential side wall opening and fluid discharge selectively through one of said central openings.

8. The filter assembly of claim 7 additionally including at least one vane formed on said uppermost disc to augment rotation thereof during discharge from said top wall opening.

9. In an automatic clothes Washing machine having an imperforate tub with an inlet and an outlet, a first pump associated with said inlet and said outlet for recirculating liquid to said tub, and a second pump associated with said outlet for discharging liquid from said tub to a drain, the improvement comprising a self-cleaning filter assembly for removing solid impurities from the recirculation flow comprising:

a housing having a bottom wall, a top wall, and a vertical side wall defining a chamber therein;

at least one outlet opening substantially centrally positioned within said bottom wall, at least one outlet opem'ng substantially centrally positioned within said top wall, and at least one inlet opening formed Within said vertical side wall and directed tangentially thereto;

a plurality of circular discs disposed one above the other in stacked relationship within said chamber; spacing means to support and separate each of said discs from adjacent discs;

the uppermost of said stacked discs being imperforate;

at least one substantially centrally disposed aperture formed in each of said discs other than said uppermost disc; and said chamber being of such cross section suflicient to accommodate free rotation of said discs therein and stacking of said discs therein with the edges thereof unaligned whereby impurities trapped along said edges of said stacked discs are prevented from forming a solid continuous blanket along said edges;

connection means adapted to connect said tangential inlet opening to the tub outlet, said bottom wall outlet opening to the first pump, and said top wall outlet opening to the second pump;

means for selectively opening and closing each of said centrally positioned outlet openings enabling one of said centrally positioned outlet openings to be opened while the other is closed;

whereby said bottom wall outlet opening is opened and said top wall outlet opening is closed to liquid discharge when the first pump is operated thereby causing said discs to form said stacked relationship and to operate as a filter during recirculation of liquid from the tub through the filter and back to the tub; and

whereby said bottom wall outlet opening is closed and said top wall outlet opening is opened to liquid discharge when the second pump is operated thereby separating and randomly rotating said discs providing a self-cleaning action thereto by the liquid being pumped from the tub to the drain.

10. The invention of claim 9 wherein said circular discs are of a uniform diameter and have a minimum crosssectional periphery sufliciently large to prevent a threadlike impurity from wrapping therearound and becoming entangled thereupon.

11. The invention of claim 10 wherein:

said spacing means comprise projections disposed at such a diameter concentric with said circular discs as to afford support for each of said discs when said discs form said stacked relationship having randomly unaligned edges;

said vertical side wall is of substantially equilateral polygonal cross section and said tangential inlet is directed parallel to one of the equilateral sides thereof; at least one vane is formed on said uppermost discs and at least one vane is formed on the lowermost of said discs to augment the rotation thereof during discharge from said opening in said top wall; and

pivotal means depending from said top wall to engage said uppermost disc during discharge from said opening in said top wall to limit upward movement of said uppermost disc and to augment the rotation thereof 'by pivoting said uppermost disc thereon.

12. The filter assembly of claim 11 additionally including a pivotal means depending from said top wall to engage said uppermst disc during fluid discharge from said opening in said top wall to limit the upward movement of said uppermost disc and to augment the rotation thereof by pivoting said uppermost disc thereon.

13. A self-cleaning filter assembly for removing solid impurities from a fluid stream comprising:

a housing defining a chamber therein;

inlet and outlet means for admitting fluid to said chamber and for discharging fluid therefrom comprising at least one opening positioned at one end of said housing and additional opening means formed within a portion of said housing other than said one end;

a plurality of discs disposed one above the other in stacked relationship within said chamber;

spacing means to separate each of said discs from adjacent discs;

said chamber being of sufiicient size to accommodate the stacking of said discs therein with the peripheral edges thereof unaligned; and

at least one substantially centrally disposed aperture formed in each of said discs other than the disc most remote from said one end, said remote disc being imperforate;

said fluid stream passing through the spaces between said stacked discs then through said apertures in said discs to flow from said opening means to said opening in said one end, whereby impurities are removed from said fluid stream at the outer edges of said discs to filter said stream, the unalignment of said outer edges of said discs acting to prevent the removed impurities from forming a continuous blanket along said edges thereby enabling said discs to separate from said stacked relationship and the impurity formation to break up when fluid is passed through said chamber and discharged by means other than said first opening for cleaning said filter assembly.

References Cited UNITED STATES PATENTS 1,975,393 10/1934 Fulcher 210357 3,006,478 10/1961 Mueller 210-356 FRANK A. SPEAR, JR., Primary Examiner US. Cl. X.R,

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