Abstract:
An aerator, that includes jet-defining slots and jet-fragmenting surface therein formed of or in molded plastic parts, is provided with a self-cleaning character that is achieved by providing a washer-shaped body that effects, upon initial flow of water into the aerator, a directed liquid flow at an increased velocity to effect a scrubbing action of the jet-defining slots to dislodge debris therefrom, and a plug member providing an open flow passageway through which the dislodged debris is then discharged, after which the flow passageway is automatically closed by a valve member and normal steady state aeration conditions then prevail in the aerator.

Description:
FIELD OF THE INVENTION 
     This invention relates to a self-cleaning aerator, for use on faucets and the like, and more particularly relates to the self-cleaning aspect of an aerator whose jet-forming element is a unitary part with jet-forming slots defined entirely within that single part. 
     BACKGROUND OF THE INVENTION 
     An essential element of all aerators is a jet-forming means provided within a casing from which a plurality of relatively fine jets of liquid, such as water, are discharged into a mixing chamber to be fragmented and mixed intimately with air, after which straightening means operate to cause a coherent stream of aerated liquid to be discharged from the aerator. The jet-forming means have typically been in the form of a perforated disc or the equivalent. 
     When usage of aerators disclosed the fact that the disc perforations tended to clog with water-borne debris, a self-cleaning aerator was developed in which the jet-defining flow apertures of a metal disc, or equivalent, were provided by two mating metal parts that were resiliently separble, during the non-flow condition, to permit debris to be flushed between the separated edges of the two parts before water pressure of the steady flow condition operated to restore the two parts to their mating condition. Such prior art constructions are disclosed in U.S. Pat. Nos. 2,707,624; 2,896,863; 2,928,607; and 3,014,665. 
     The use of plastic apertured discs in aerators has operated to reduce the cost of the aerator. But the use of plastic parts to define jet-forming flow apertures did not permit effective use of the same self-cleaning feature as first disclosed in U.S. Pat. No. 2,707,624. It has been the experience that jet-defining flow apertures preferably be provided in their entirety in a single part, and should not be defined between edges of two mating parts. 
     One of the most effective designs of an aerator using plastic internal parts is disclosed in U.S. Pat. No. 3,684,191 wherein one internal part is in the form of an annular guide ring, and a second internal part, made wholly of plastic, is in the form of a flanged, cup-shaped, plug member with a series of fine vertical jet-forming slots defined therethrough. The fine vertical slots in the plug member are susceptible of being clogged by water-borne debris. 
     It is, therefore, one object of this invention to provide self-cleaning character for an aerator whose jet-forming apertures are defined in a molded plastic part, whereby water-borne debris may be automatically flushed from the aerator without disassembly of the aerator, or removal of the aerator from its operative environs. 
     It is another object of this invention to provide a self-cleaning aerator wherein the liquid flow therethrough is automatically controlled to effect, upon initial liquid flow, an increased and directed liquid velocity therethrough to effect a directed scrubbing, and debris dislodging, flow action over the jet-forming apertures, after which a steady state condition, for which the aerator is designed, will be established. 
     A further object of this invention is to provide a self-cleaning aerator that is characterized by economy of construction and effectiveness of operation. 
     Further objects and advantages will become apparent to one skilled in the art from the following description of preferred embodiments of the invention. 
     BRIEF SUMMARY OF THE INVENTION 
     An aerator with internal plastic parts of the type generally disclosed in U.S. Pat. No. 3,684,191 is provided with self-cleaning character by modifying the jet-forming, cup-shaped, plug member to provide a central flow opening therein through which debris may be discharged after being flushed and scrubbed, by liquid flow, from the jet-forming slots or apertures in the plug member. 
     To effect flushing and scrubbing of the jet-forming slots, an upstream apertured washer is provided with concentric flow aperture means therein. The inner flow aperture means is normally closed by a resiliently-biased, flow-blocking, valve member when there is no flow through the aerator, and so that initial flow of water through the aerator is directed through the outer flow aperture means which are positioned to direct a sheet of liquid, at increased velocity, over and across the jet-forming slots downstream of the washer, to effect a scrubbing of debris from said slots and to effect discharge of the debris and initial flow of liquid downstream through the central flow opening of the plug member. 
     The application of liquid force against the flowblocking valve member does cause same to move downstream against the resilient bias force transmitted from a helical spring. The downstream shape of the valve member is selected and arranged to complement and close the central flow opening in the plug member. A resilient flange provided on the valve member is shaped and arranged to form a seal with a shaped seat surrounding the central flow opening in the plug member, so that during steady state operation the aerator operates as disclosed in U.S. Pat. No. 3,684,191. 
     The slight time delay, between the two extremes when there is initial liquid flow and when the valve has seated to close the central flow opening in the plug member, provides a time period when there is provided desirable fluctuating pressure drops and surges in the region adjacent the jet-forming slots that aids in dislodging and flushing debris that has been temporarily lodged in the jet-forming slots of the plug member. 
     The flow-directing washer is of shape-retaining character to insure obtaining the desired flow therethrough and downstream thereof. While it may be possible to effect a liquid-tight seal thereagainst, a distortable, resilient washer is included upstream of the shape-retaining washer to insure the required liquid-tight seal between the aerator and the discharge spout of a faucet. 
     The aerator itself may be provided with any means for attachment, including a male threaded or female threaded casing as seen in FIGS. 1 and 5 of U.S. Pat. No. 3,684,191, and the casing itself may be enclosed within an outer imperforate casing, or sleeve, that provides surrounding vertical air passageways, that provide the known effect of a slotless aerator, the latter also being disclosed in said U.S. Patent. 
     The invention herein will be better understood by reference to the following detailed description when considered in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a vertical axially cross-sectional view through one form of aerator constructed in accord with the features and principles of this invention; 
     FIG. 2 is a cross-sectional view taken substantially on line 2--2 of FIG. 1, showing the flow passageways through the washer and the relationship of those passageways with the jet-forming slots in the plug member that is downstream of the washer; and 
     FIG. 3 is a fragmentary view, partly in elevation and partly in cross-section, showing the lower portion of the casing and interior construction of a modified form of aerator construction. 
    
    
     Like parts in FIGS. 1 and 3 are identified by same numeral, and where a modification is made, similar parts carry the same numeral primed. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, there is shown in FIG. 1 an aerator generally indicated at 10 that includes an axially elongated casing 12 having upstream and downstream ends respectively at upper and lower ends of the Figure. The specific casing shown is female threaded at 14 at the upstream end, and the casing provides an inturned flange 16 at the downstream end to support the lowermost screen that is hereinafter referred to. 
     The side wall of casing 12 is provided with three slots 18 through which air is ingested into a mixing chamber 20 that is located generally centrally of the ends of the casing. The downstream end of mixing chamber 20 is bounded by upper and lower disc-like screens 22 and 24 of very coarse mesh, contrasted with fine mesh screens normally used in aerators, separated by a ring-like spacer 26 that is press fit into position with casing 12. While two screens are shown, the use of more screens or only one screen is also contemplated. The casing 12 is provided with an internal groove 28 that receives a split ring screen retainer 30 that extends inwardly to overlie the peripheral edge of the upper screen 22. The lower screen 24 abuts inturned flange 16. 
     The casing 12 is provided with an annular support shoulder 32, upstream of the air intake slots 18, which serves as a support for aerating parts positioned upstream of mixing chamber 20. The aeratoring parts include an annular guide ring 34 that is a unitary part molded of a plastic, preferably Delrin. Guide ring 34 is shaped to provide thereon an annular convex impingement surface 36 which extends radially inwardly and curves in a downstream direction. The portion of surface 36 against which the liquid jets impinge is located outwardly and downwardly of the apertures through which the liquid jets issue. Guide ring 34 has an upstream, annular, support edge surface 38 located in a plane that is perpendicular to the longitudinal axis of casing 12. 
     The aerating parts also include a cup-shaped plug member, generally 40, that is also molded of a plastic, preferably Delrin. Plug member 40 has a generally shallow cup shape, and has an annular support flange 42 extending radially outwardly. The support flange 42 is slidingly telescoped into and supported on guide ring 34, with the lower edge of flange 42 engaging the uppermost part of convex surface 36. The plug member 40 provides an upright, generally cylindrical, side wall 44 that projects downstream from the radial inner edge of the annular peripheral flange 42. The upstream surface 46 of the support flange 42, and upstream edge of wall 44, lie in the same plane as the annular support edge 38 of the guide ring. 
     The upright side wall 44 is provided therein with a series of circumferentially spaced, axially elongated, radial slots 48 that extend downstream from the upstream side 46 of the support flange 42. The slots 48 operate to form and provide the liquid jets required to be fragmented to effect aeration of liquid passing through the aerator. The slots 48 extend part way down the axial length of side wall 44 and provide radially outwardly disposed discharge ports 49 that are seen below flange 42, and which are constructed to direct liquid jets issuing therefrom against the surface 36 on the guide ring 34. The lower end of wall 44 turns inwardly to provide a transverse wall 50 on the cup-shaped plug member 40. 
     What has thus far been described are construction features for aerators that are disclosed in U.S. Pat. No. 3,684,191. The improvement features of the instant invention will now be described. 
     In the form of invention shown in FIGS. 1 and 2, the plug member 40 is formed as an annulus having a relatively large central flow opening 52 through its downstream transverse wall 50. The opening 52 is bounded by a downstream cylindrical bore and an adjacent upstream inclined seat 56 that tapers downwardly and inwardly. 
     A shape-retaining washer 58, molded of plastic, preferably polyethylene, is positioned above coplanar surfaces 38 and 46 respectively of guide ring 34 and plug member 40. The shape-retaining washer 58 is supported at least upon the annular support edge 38 of guide ring 34, but as shown, the outer annulus 60 of washer 38 also overlies and engages a portion of surface 46 of plug member 40. 
     The washer 58 has radially spaced outer and inner concentric annular lands, respectively 60 and 62, joined together by four circumferentially spaced radial lands 64. The inner annular land 62 surrounds and defines a central flow passageway 66. The annulus between the outer and inner lands 60 and 62 has provided therein a plurality of circumferentially spaced primary flow passageways 68 that are shown to be of arcuate, generally oval, shape and through which initial flow of liquid is directed downstream, in a manner to flush against, scrub, and dislodge from the slots 48 any debris that may have become lodged therein. The debris that is flushed from slots 48 will then pass downstream through the central flow opening 52 of said plug member 40, and will easily pass through coarse mesh screens 22 and 24 out of the aerator. 
     There is also provided, downstream of the shape-retaining washer 58, a flow-blocking valve member 70 molded of plastic, preferbly Delrin. The valve member 70 is a body of revolution providing an inverted cup shape with an upstream transverse wall 72 and an axially-extending cylindrical side wall 74 that surrounds a recess 75. The valve member 70 is adapted to engage the downstream side of washer 58, prior to start of flow through aerator 10, to block flow of liquid through the central flow passageway 66. 
     Provided concentrically on valve member 70, and as part thereof, is an annular flange 76 that is cantilevered from side wall 74 through a frusto conical connecting flange 78. At least an annular portion of the upstream edge of flange 76 engages land 62 simultaneously with wall 72. An annular recess 80 is defined between concentric sidewall 74 and flange 76. The diameter of central flow passageway 66 in washer 58 is less than the diameter of transverse wall 72. The diameter of opening 52 in plug member 40 is greater than the diameter of transverse wall 72 and the diameter of side wall 74, but is less than the maximum diameter of frusto conical wall flange 78. When the valve member 70 is moved by flow of liquid, downstream to its position shown in phantom by broken lines in FIG. 1, the downstream surface of frusto conical flange wall 78 engages and seats against the inclined wall 56 on plug member 40. 
     The thickness of the flange walls 76 and 78 and the nature of the plastic material, Delrin, of which part 70 is formed, are such that flange wall 78 will, under pressure of flowing liquid entering recess 80 during steady state flow conditions in the aerator, flex and deflect as needed to cause frusto conical flange wall 78 to conform to the shape of the seat 56 defined on the plug member 40, to the end that a seal is formed between members 70 and 40 to prevent flow of liquid through the central aperture 52 of the plug member. 
     The means for maintaining the valve member 70 in its upstream position, as shown in full lines in FIG. 1, includes a helical spring 82 having an upstream end 82a, that is press fit into the recess 75 of valve member 70, and a downstream end 82b that is flared outwardly in a generally conical shape, as shown. The lowermost portion of spring end 82b engages and is supported by the screen 22. To prevent lateral movement of the spring end 82b, the central portion of screen 22 is deformed to provide an upstream bulge 23, generally of rounded pyramidal shape, that serves as a stud over which the spring end 82b fits. In an alternate form of construction, shown in FIG. 3, the aerator uses a flat screen 22&#39;, and the spring end 82b merely engages screen 22&#39;. 
     The outer annular land 60 of the washer 58 is of such radial width that a radial inner portion thereof overlies a portion of upper annular support flange 42 of the plug member, and this arrangement serves to substantially block flow of liquid through the joint defined between the annular guide ring 34 and the plug menber 42. 
     The shape-sustaining washer 58, when made of polyethylene, has sufficient resiliency for use as a deformable washer to effect sealing during connection of the aerator 10 with the discharge end of a spout to which the aerator is to connect. If greater sealing resiliency is required because of the nature of material, such as Delrin, used to form washer 58, then a resilient rubber washer 84 should be used to effect a sealing relationship of the aerator 10 with a faucet spout. The resilient, deformable washer 84 would rest upon washer 58, as seen in FIG. 1, and has an inner diameter substantially as shown that is selected to avoid interfering with flow through primary flow apertures 68 in washer 58. 
     Reference is made to FIG. 2 which illustrates many of the slots 48 of the plug member 42 being exposed through primary flow apertures 46, so that water passing through apertures 46 will flush from the exposed fine slots 48 any debris that may have been captured in those slots. The total washer aperture area, of all the primary flow apertures 68 and central flow aperture 66, and shape and location of apertures 68 are selected relative to the position and discharge capacity of slots 48 so that when central aperture 66 is blocked, when flow is first initiated, there is provided a directed liquid flow through apertures 68 at increased velocity to effect a scrubbing action of the jet-defining slots 48 to dislodge debris therefrom. It will be appreciated that until the valve member 70 has been fully depressed to the broken line position in FIG. 1, there can be higher liquid velocity and pressure developed by the fluid passing through flow passageways 68. The liquid pressure drops and surges in the region adjacent the slots 48, during the brief time period before valve member 70 seats against plug member 40 and establishes a steady flow-condition, aids and contributes to the scrubbing and flushing action of the liquid in effecting cleaning of debris that may be temporarily lodged in slots 48. 
     While particular embodiments of this invention have been shown and described, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention and, therefore, it is intended in the appended claims to cover all such changes and modifications which fall within the true spirit and scope of the invention.