Patent application title: Method of regulating pool surface agitation at low pump rpm using butterfly valve eyeball fittings
Sean Patrick Walsh (Riverhead, NY, US)
Robert Charles Raynor (Longmeadow, MA, US)
IPC8 Class: AE04H414FI
Class name: Pool type construction details including water inlet or outlet means
Publication date: 2011-09-15
Patent application number: 20110219531
A method of improving pool surface agitation, to reduce settling of
debris at low filter pump RPMs, comprising use of standard eyeball
fittings that permits unrestricted return flow, and a second eyeball
fitting configuration comprising a bi-fold split-disk butterfly valve
being normally biased into a closed position. The biasing is calibrated
to selectively inhibit filter pump return flow below a threshold flow
rate. One or more standard eyeball fittings and one or more second
eyeball fittings are alternately installed in a pool's sidewall. When the
filter pump is operated at high RPMs, the selective return flow comprises
return flow being discharged through standard eyeball fittings and
through second eyeball fittings; and when the filter pump setting is
reduced whereby return flow is below the threshold, the selective return
flow comprises butterfly valves in second eyeball fittings closing, with
the return flow being discharged solely through the standard eyeball
1. A method of improving pool surface agitation to reduce settling of
debris at low filter pump RPMs, using butterfly valves in eyeball
fittings, said method comprising: a first eyeball fitting, said first
eyeball fitting permitting free return flow of filter pump water, one or
more of said first eyeball fittings being installed in a pool; a second
eyeball fitting, said second eyeball fitting comprising a bi-fold
split-disk butterfly valve being normally biased into a closed position
with said biasing being calibrated to selectively inhibit return flow of
filter pump water, one or more of said second eyeball fittings being
installed in said pool to be interspersed between said installation of
said one or more first eyeball fittings.
2. The method according to claim 1, wherein when said filter pump is set to operate at high RPMs, said selectively inhibited return flow comprises said return flow being discharged through said first eyeball fittings and through said second eyeball fittings.
3. The method according to claim 2, wherein when said filter pump setting is reduced from said high RPMs, said selectively inhibited return flow comprises said butterfly valve in one or more of said second eyeball fittings partially closing, and said return flow being discharged through said first eyeball fittings and discharged partially through said second eyeball fittings.
4. The method according to claim 3, wherein when said filter pump setting is further reduced to operate at low RPMs, said selectively inhibited return flow comprises said butterfly valve in each of said second eyeball fittings completely closing, and said return flow being discharged solely through said first eyeball fittings.
5. The method according to claim 4, wherein said biasing of said bi-folding split-disk is by a torsion spring.
6. The method according to claim 5, wherein said one or more first and second eyeball fittings installed in said pool comprises a plurality of first eyeball fittings and a plurality of said second eyeball fittings being installed in said pool.
7. The method according to claim 6, wherein said torsion springs in each of said plurality of second eyeball fittings each comprises a unique spring constant resulting in closing of said second eyeball fitting across a spectrum of flow rates.
8. The method according to claim 7, wherein a number of said plurality of first and second eyeball fittings, and said closing of said second eyeball fittings across a spectrum of flow rates, is calibrated to occur based upon length and width dimensions of a pool.
9. A method of improving pool surface agitation at low filter pump RPMs using flow control valves in eyeball fittings to reduce settling of debris, said method comprising: a first eyeball fitting, said first eyeball fitting permitting free return flow of filter pump water; one or more of said first eyeball fittings being installed in one or more sidewalls of a pool; and a second eyeball fitting, said second eyeball fitting comprising a valve being biased to inhibit return flow of filter pump water being at or below a threshold flow rate, one or more of said second eyeball fittings being installed in said one or more sidewalls of said pool to alternate with said installation of said one or more first eyeball fittings.
10. The method according to claim 9, wherein when said filter pump is operating at high RPMs, said return flow is discharged through said first eyeball fittings and through said second eyeball fittings; and wherein when said filter pump is operating at low RPMs to produce return flow at or below said threshold rate, said valve in each of said second eyeball fittings is biased closed, and said return flow is discharged solely through said first eyeball fittings.
11. The method according to claim 10, wherein said valve comprises a bi-fold split-disk butterfly valve.
12. The method according to claim 11, wherein said butterfly valve comprises a bi-folding split-disk butterfly valve.
13. The method according to claim 12, wherein said bi-folding split-disk of said butterfly valve is biasing by a torsion spring.
14. The method according to claim 13, wherein said one or more first and second eyeball fittings installed in said pool comprises a plurality of first eyeball fittings and a plurality of second eyeball fittings being installed in said pool.
15. A swimming pool eyeball fitting comprising: a housing; said housing being adapted to have a portion therein be installable into an orifice in a pool sidewall; a tubular sleeve; a bi-folding split-disk assembly; said split-disk assembly comprising: a pair of demi-disks, a biasing means, and an axle; each of said pair of demi-disks being pivotally attached to said axle and being biased by said biasing means to be in-line in a closed position, and wherein when said biasing is overcome by return flow to deflect said demi-disks, said demi-disk then being oriented to be parallel to each other in an open position; said split-disk assembly being mounted in said sleeve with a first end and a second end of said axle being received in corresponding first and second orifices in said sleeve; said tubular sleeve with split disk assembly being installed into an opening in said housing; an eyeball, said eyeball being received in an opening in said tubular sleeve; and a cover plate, said cover plate serving to retain said eyeball within said tubular sleeve to be moveable therein.
16. A swimming pool eyeball fitting according to claim 15, wherein said biasing means comprises a torsion spring
17. A swimming pool eyeball fitting according to claim 16, wherein said pivotal mounting of said demi-disks upon said axle comprises a clevis on each of said demi-disks, said clevis comprising an orifice to receive said axle therethrough.
18. A swimming pool eyeball fitting according to claim 17, wherein said axle comprises a hollow cylinder, a helical compression spring, and two pins; and wherein said helical compression spring is disposed within said cylinder to bias said first and second pins to protrude out from first and second ends of said cylinder.
19. A swimming pool eyeball fitting according to claim 17, wherein said axle comprises a cylinder, and said corresponding first and second orifices in said sleeve comprises in-line through-holes to slidably receive said axle.
20. A swimming pool eyeball fitting according to claim 18, wherein at least a portion of said tubular sleeve comprises a spherical interior surface and at least a portion of said eyeball comprises a spherical outer surface; and wherein said eyeball being moveable within tubular sleeve comprises said spherical exterior surface of said eyeball permitting eyeball adjustment to variable angular orientations relative to said spherical interior surface of said tubular sleeve.
CROSS REFERENCE TO RELATED APPLICATIONS
 This application claims priority on U.S. Provisional Application Ser. No. 61/280,603 filed on Nov. 5, 2010, the disclosures of which are incorporated herein by reference.
FIELD OF THE INVENTION
 The present invention relates to improvements in flow return (eyeball) fittings for swimming pools, and more particularly to a method of using such fittings which are capable of regulating flow, for improving pool water surface agitation for a pool with a variable speed pump operating at low RPMs.
BACKGROUND OF THE INVENTION
 Many homes today have been upgraded or even built from scratch to incorporate a swimming pool. In certain parts of the country, particularly the southern states, the percentage of homes with either an in-ground or an above-ground pool is even greater due to the higher temperatures and longer usable season, despite the inconvenience of, and the costs associated with, maintaining the pool. The inconvenience has been virtually eliminated with the proliferation of and competition between companies that cater to servicing and maintaining of a homeowner's swimming pool. While some of the costs may be attributed to the fees for such services and chemicals or other products required annually, another significant source of a pool's expenses may be attributed to the utility costs incurred.
 Electricity consumed by a pool's filter pump is sizeable, but appropriate periods of filtration are necessary to maintain the pool water in a serviceable condition. Recommended periods of filter use vary throughout the country, and although some pool owners operate their pool pump and filter on an 8-hour on/16 hour-off cycle, the pump is more preferably operated to filter 24 hours a day during the applicable seasonal. The 24-hour cycle is preferable because constant circulation serves not only to remove dirt and debris, but also to prevent algae outbreaks and pH swings, which serves to reduce the related maintenance costs. But the energy consumption involved in this consistent usage can account for up to 60% of a homeowner's summer utility bills, making his or her summer energy costs far more expensive than winter heating costs.
 A key factor in properly selecting a swimming pool filter pump is the turnover, meaning the amount of time it takes to move a volume of water equal to that stored in the pool, through the filter system once. Where a pool experiences high usage, it may be recommended in certain regions to use a six-hour turnover; for medium usage, an eight-hour turnover; and for low use, a ten hour turnover. The turnover, along with the pool's size and necessary flow rate will lead a purchaser to an optimal single-speed pump size, with its associated cost. However, many pool retailers use upgrades in the pump size as a marketing incentive to beat the competition, making them needlessly oversized. Therefore, the filter pump will be energy inefficient due to its RPM speed rating for the proper turnover rate, and will be even more wasteful when utilized in a highly desirable 24-hour cycle. As a result, some states, including California and Florida, have taken legislative action recently to regulate residential pool pump efficiencies.
 The problem has been largely addressed with the introduction of variable-speed pool pumps, which are commercially available today. Use of a properly sized, high-efficiency, variable-speed pump on a 24-hour basis--which will normally be at a correspondingly lower RPM setting--will in fact be less expensive than the oversized fixed-speed pump operated only part-time throughout the day.
 However, the variable speed pump, by running at different speeds in revolutions per minute, will vary the amount of water being returned to the pool in gallons per minute, which presents a new problem. The water being delivered to the standard pool-wall eyeball fittings, of which U.S. Pat. No. 4,717,078 serves as an example, at energy efficient low rpm settings, will occur at too low of a flow rate. This lower flow rate that occurs at each of the pool's eyeball fittings, while advantageously using less energy, will adversely produce insufficient surface agitation of the water. Prior art methods usable to address this problem, such as the one shown by expired U.S. Pat. No. 4,503,573 to Handzel, have heretofore only offered complex and costly solutions. The invention disclosed herein more elegantly addresses this problem in selectively restricting flow to certain returns, to thereby allow greater flow to the remaining returns. This creates the desired water agitation while still permitting energy savings by running the variable speed pump at a lower speed, without the use of expensive components and redundancy. (Note--all references cited in this document are incorporated herein in their entirety by reference).
SUMMARY OF THE INVENTION
 A bi-fold split-disk butterfly valve is configured to be incorporated into a standard pool eyeball fitting to create a more functional arrangement. The bi-fold split-disk butterfly valve fitting may contain a housing that is installable into the side wall of a pool. The housing may provide support for a sleeve, into which is installed a bi-fold split-disk assembly (FIG. 8). The bi-fold split-disk assembly may be comprised of a pair of demi-disks, each of which may have a clevis protruding from the back face. The clevis may be offset from the center so that two demi-disks could be pushed together to form a full circular disk shape, with the clevis of one demi-disk fitting up against the clevis of the other demi-disk, and thereby be pivotally mounted onto an axle using the holes through the walls of each clevis.
 The axle may be a hollow cylinder containing a helical compression spring that is trapped therein by two pins which have exposed, and rounded edges. Wrapped about the outside of the axle may be a helical spring having straight ends extending away from the coils to provide torsional biasing of the two demi-disks. The demi-disks may each have a recessed area to positively retain the straight ends of the torsion spring. The spring biased pins of the axle may be used to install the bi-fold split-disk assembly into co-axial holes in the sleeve.
 With the bi-fold disk assembly installed into the sleeve, the assembly would be normally biased to a closed position (FIGS. 10 and 11) with the two demi-disks being in-line to block the path of the water flowing within the sleeve. The demi-disk could be maintained in the closed position, with over-travel being prevented, by having stops on the disks. The clevis of the respective demi-disks could include a protrusion which, once the two demi-disks were biased in-line to form the full circular disk shape, would make contact and serve as a stop to prevent further rotation about the axle.
 The sleeve may have a spherical internal surface to accommodate installation of a spherical eyeball that could be used to direct the flow of water from the pump to different regions of the pool. The eyeball may be rotatably retained in the sleeve by attachment of an eyeball cover plate, which has a spherical internal surface to mate with the spherical eyeball.
 In normal operation, when the variable flow pump is advanced to a high speed, the static pressure would overcome the biasing of the torsion spring to rotate both demi-disks to the open position (FIG. 6), in which they are parallel to each other. Dynamic pressure of the fluid flow would keep the demi-disks in the open position until the pump speed was changed. When the pump speed is reduced, the biasing would overcome the reduced dynamic fluid pressure and cause the demi-disks to rotate to be in-line and essentially form a single disk, which blocks the fluid flow path.
 Since a pool may have multiple eyeball return fittings and the filter pump may operate at various speeds, one or more of those fittings may be equipped without the valve of the current invention, one or more may be equipped with a valve having a low stiffness for the torsion spring, and one or more may be equipped with a valve having a higher spring stiffness. Such an arrangement would permit flow through only as many return fittings as necessary to create sufficient agitation, and the fittings through which flow was occurring would correspond to the speed setting of the pump. At a low setting, flow would be through the fittings having no valve therein, and the fittings with a valve utilizing a low spring rate. At a high setting, flow would be through all of the fittings.
BRIEF DESCRIPTION OF THE DRAWINGS
 FIG. 1 is a perspective view of the eyeball fitting of the present invention which includes a bi-fold split-disk butterfly valve.
 FIG. 2 is an exploded view of the parts comprising a first embodiment of the eyeball fitting of the present invention with a bi-folding split-disk butterfly valve.
 FIG. 3 is an enlarged perspective view of the eyeball fitting of the present invention with the bi-fold butterfly valve in the fully-closed position.
 FIG. 4 is a reverse perspective view of the eyeball fitting of the present invention, with the bi-fold butterfly valve in the fully-closed position.
 FIG. 5 is a front view of the eyeball fitting of the present invention, with the bi-fold butterfly valve in the fully-closed position.
 FIG. 6 is a front view of the eyeball fitting of the present invention, with the bi-fold butterfly valve in the fully-open position.
 FIG. 7 is a perspective view of the eyeball fitting of the present invention, with the bi-fold butterfly valve in the fully-open position.
 FIG. 8 is a perspective view of a first embodiment of the bi-fold split-disk assembly of the butterfly valve prior to installation in the eyeball fitting of the present invention.
 FIG. 9 is a perspective view of the axle of the bi-fold split-disk assembly in FIG. 8.
 FIG. 9A is a perspective view of an alternate embodiment of the axle of FIG. 9.
 FIG. 10 is a perspective view of the bi-fold split-disk assembly after being installed into the sleeve of the eyeball fitting of the present invention, with the valve in the fully-closed position.
 FIG. 11 is a reverse perspective view of the eyeball fitting of FIG. 10.
 FIG. 12 is a top view of an in-ground pool, which incorporates into its filter system, within the pool's sidewalls, the eyeball fitting with the bi-fold split-disk butterfly valve of the present invention
 FIG. 13 is a section view through the in-ground pool of FIG. 12.
 FIG. 14 is an exploded view of the parts comprising a second embodiment of the eyeball fitting with bi-fold split-disk butterfly valve of the present invention.
 FIG. 15 is an enlarged view of the alternative embodiment of the split disks and axle of FIG. 14.
 FIG. 16 a rear perspective view of the alternative embodiment of the sleeve of FIG. 14, with the alternative split disks and axle assembled therein.
DETAILED DESCRIPTION OF THE INVENTION
 FIG. 1 shows a perspective view of a first embodiment of the eyeball fitting 10 with a bi-fold split-disk butterfly valve of the present invention, while FIG. 2 shows the parts comprising one embodiment of the eyeball fitting in an exploded view. The eyeball fitting 10 with a bi-fold split-disk butterfly valve may be comprised of a housing 11, a bi-fold split-disk assembly 70, a sleeve 30, an eyeball 43, and an eyeball cover pate 50.
 The housing 11 may have a cylinder 12, which may be threadably inserted into a receptacle 90 that is installed in the sidewall 100 of a pool (FIG. 12). Cylinder 12 of housing 11 may have a first end 13, which is the end that is initially inserted into the receptacle 90, a second end 14, an outer cylindrical surface 15 which may have external threading over at least a portion of the surface, and an inner cylindrical surface 16. Extending from second end 14 of the cylinder 12 may be a face plate 19. Face plate 19 may have a curved surface 20 that may begin at the inner cylindrical surface 16 and terminates on a side edge 21. Face plate 19 of the housing 11 may also be comprised of a shoulder 22 that extends approximately orthogonally from side edge 21 down to the outer cylindrical surface 15. The housing 11 may also be comprised of an inner wall 17 that protrudes inwardly from the inner cylindrical surface 16, but does not completely obstruct the opening, and generally only protrudes a short distance from inner cylindrical surface 16. There may also be a plurality of notches 18 equally spaced radially about the inner wall 17, which may serve to receive a tool that can be used to apply torque to the housing 11 when installing it into the receptacle 90.
 The housing 11 being so constructed may receive the sleeve 30 and the bi-fold split-disk assembly 70, which are shown assembled together in FIGS. 10 and 11. The bi-fold split-disk assembly 70 may consist of two identical demi-disks 71 that are mounted upon an axle assembly 60. The axle assembly 60 (FIG. 9) may be comprised of an axle cylinder 61, into which is installed a compression helical spring 62 that is located between a pair of pins 63. Pin 63 may preferably be cylindrical, and may have one rounded end 64 and a flat end 65. The flat end 65 may be installed inwardly into the axle cylinder 61 to contact the compression coil spring 62, while the outwardly pointing rounded end 64 of each pin 63 may be used to engage a hole in sleeve 30, as described hereinafter.
 The demi-disk 71 may preferably be approximately one-half of a circular disk, having a diametrical edge 73, and flat edge 72 which is located roughly through the center of the circle diametrical edge 73. The diametrical edge 73 may be sized to match the sleeve 30. Demi-disk 71 may also have a generally flat front face 74 and back face 75. Protruding from the back face 75 of demi-disk 71 may be a pair of walls 76 that form a clevis, with each wall having a hole therein to form a pair of coaxial holes. Each of the walls 76 of the clevis may preferably protrude past flat edge 72, whereby the axis of the coaxial holes may be approximately coplanar with the flat edge 72. Back face 75 may have a flat recessed area 77 located between the walls of the clevis 76. The clevis 76 (and recess 77) may preferably be offset from being centered on the back face 75 of demi-disk 71 by approximately one-half of the thickness 78 of the wall 76 of the clevis. This offsetting of the clevis 76 on back face 75 of demi-disk 71 permits two identical demi-disks 71 to be pushed together as shown in FIG. 8, such that the two half-disks approximately form a complete circular disk shape being usable to inhibit fluid flow through the sleeve.
 In between the respective clevis walls of the two demi-disks 71 may be one or more helical springs 80 with pairs of straight ends 81 extending therefrom. The straight ends 81 may be received in the recess 77 of each respective demi-disk, and may alternatively just contact the flat back face 75. The axle assembly 60 may be inserted through the holes of the first walls of the clevis 76 of each demi-disk, and through the coils 82 of the helical spring(s) 80, and finally through the second walls of the clevis 76 of the two demi-disks, as seen in FIG. 8. With the demi-disks 71 pivotally mounted on the axle assembly 60 as described to form the bi-fold split-disk assembly 70, the straight ends 81 of the helical spring 80 being received in the recess 77 of each demi-disk 71 serves to permit the helical spring to act as a torsion spring and bias the two demi-disks to a closed position, which is described hereinafter.
 The bi-fold split-disk assembly 70 may be mounted into the sleeve 30 as seen in FIGS. 10 and 11. The sleeve 30 may be comprised of a first cylinder 31 (FIG. 2) having a first end 32, a second end 33, an outer cylindrical surface 34, and an inner cylindrical surface 35. The inner cylindrical surface 35 may include a pair of coaxial holes 41, to receive the rounded end 64 of pins 63 of the axle assembly 60 of the bi-fold split-disk assembly 70. The coaxial holes 41 may each begin at the inner cylindrical surface 35 and just have the minimal depth needed to receive the axle assembly 60, and not be bored so deep as to pierce the outer cylindrical surface 34 (FIG. 2). In an alternative embodiment, the coaxial holes may each be through-holes 41A, and pierce the outer cylindrical surface 34 (FIG. 14), which permits use of axle 60A in the form of a plain cylinder (no pins or helical spring) and allows for easier assembling. Additionally, demi disks 71A may be used, in which the flat edge 72 is replaced by an edge 71B that includes the stepped cutouts shown in FIG. 14, which may serve to prevent the flaps from rotating on the axis.
 In another alternate embodiment, the axle cylinder 61 of axle 60 may have a rectangular-shaped protrusion 65 that extends downward (FIG. 9A). The protrusion 65 may be received in a rectangular opening that enlarges hole 41 to produce a "keyway" (hole 41 plus rectangular opening) and "key" (axle 61) arrangement, which may serve to prevent rotation of the axle assembly 60. The alternate embodiment may also have the clevis 76 with a corresponding protrusion to engage protrusion 65 of the rotation inhibited axle cylinder 61, and thus prevent rotation or fluttering of the entire bi-fold split-disk assembly 70, which may otherwise, depending of the flow characteristics, fold up to have the disks be parallel, but alternately pivot to close off one-half of the opening leaving the other half open for return flow, and then pivot in the opposite direction to close of the other half, leaving open the previously closed off one-half.
 To one familiar with the art, it should be apparent that other possible means of preventing rotation are possible, including, but not limited to, bonding the axle cylinder 61 to the sleeve 30, or having the outer surface of the axle cylinder 61 have a rectangular cross-section locally at the ends, which may be slidably received by rectangular openings in first end 31 of sleeve 30, rather than in holes 41. It may be seen from this description that where protrusion 65 is used in conjunction with the axle cylinder 61 that has a cylindrical outer surface, the rectangular protrusion could also be slidably received in such a small rectangular opening, while the pin 63 may need to be depressed to be simultaneously received by the hole 41.
 As previously mentioned, as to sizing of the diametrical edge 73 of the demi-disk 71, its size should preferably be set to provide minimal clearance with the diameter of the inner cylindrical surface 35, and the coaxial holes 41 may preferably be located near first end 32. With the holes being so located, the torsionally mounted helical spring 80 may bias the two demi-disks 71 of the bi-fold split-disk assembly 70 to a position in which the disk's front face 74 may be approximately flush to the first end 32 of first cylinder 31 of the sleeve 30 (FIG. 11). The demi-disks 71 may include stops (such as the stepped cutouts of edge 71B of disk 71A, in which a portion may overlap to serve as a stop) to limit its pivotal movement, caused by spring biasing, to the point where the two demi disk's front faces 74 are planar as shown in FIG. 11. The positions of the demi-disks may hereinafter be referred to as being "in-line," with the valve being in a closed position to inhibit flow, and being "parallel" to each other, with the valve being in an open position to permit flow.
 The first cylinder 31 of the sleeve 30 may connect to a second cylinder 36, which may begin at the second end 33 of the first cylinder and run to a second cylinder end 37. Second cylinder 36 may have an outer cylindrical surface 38, which may be formed to have a greater diameter than outer cylindrical surface 34, and thus create a step 40. Second cylinder 36 may also have an inner surface 39. Inner surface 39 may be cylindrical, or may alternatively be spherical, or it may comprise a spherical surface transitioning into a cylindrical surface.
 With the bi-fold split-disk assembly 70 mounted into the sleeve 30, as described, the combination (seen in FIGS. 10 and 11) may then be mounted into housing 11 so that the outer cylindrical surface 38 of the second cylinder 36 of the sleeve 30 makes sliding contact with the inner cylindrical surface 16 of the housing 11, until the first end 32 of the first cylinder 31 contacts the inner wall 17 of housing 11 (FIG. 4). The installation may be made permanent through the use a fastening means including, but not limited to, mechanical fasteners, glue or epoxy, or external threading on outer cylindrical surface 38 of the second cylinder 36 of the sleeve 30 along with internal threading on the inner cylindrical surface 16 of the housing 11. The installation may also be retained by being trapped therein through the installation of eyeball 43 and eyeball cover plate 50, as discussed hereinafter. If used, the selection of a fastening means may depend on the materials used to construct the various parts of the bi-fold split-disk butterfly valve 10 of the present invention. The parts may be metallic or plastic, although they may preferable be formed of polyvinyl chloride (PVC). The demi-disk 71 may be formed of a high-density plastic to resist deflection and creep deformation resulting from dynamic pressures--the sustained impact pressure of the fluid flow.
 As seen in FIG. 4, the notches 18 in wall 17 of housing 11 should be of sufficient depth to accomplish its function in providing a means of applying torque to install the housing, but preferably will not be full depth down to inner surface 16, which could serve as a leak path. Additionally, the height of wall 17 may be set so as to remain clear of the demi-disks 71 of the bi-fold split-disk assembly 70, which may necessitate having the stops in the demi-disks as previously described to prevent the torsion spring 80 from biasing the two demi-disks past the fully closed position of FIG. 4. Rather than incorporating the stops, the height of wall 17 may also be increased to provide a means of limiting rotation of the demi-disks 71 in traveling from the valve's open position in FIGS. 6 and 7, to the closed position in FIGS. 3 and 4. Also, rather than using a stop or the increased wall height, the torsion spring 80 may be designed so as to be in an undeflected position when the disks are in-line in the closed position. However, this arrangement may not provide sufficient biasing with the disks being only slightly deflected, and undesirably result in a leak path that reduces pressure.
 Once the combination of the bi-fold split-disk assembly 70 and sleeve 30 (FIG. 10) is mounted into the housing 11 (FIG. 4), the eyeball 43 may be mounted into the sleeve 30. The eyeball 43 may have a spherical outer surface 44, with a flat first end 45, a second end 46, and an inner surface 48. The eyeball 43 may be mounted into the sleeve 30 by having the spherical outer surface 44 of eyeball 43 mate with the spherical inner surface 39 of the second cylinder 36 of the sleeve 30, and provide for multiple degrees of freedom in its movement. The eyeball 43 would thereby be enabled to swivel and direct the return flow into the pool as desired, as discussed hereinafter and as illustrated in FIGS. 12, 12A, and 13. Alternatively, eyeball 43 may additionally have a cylindrical portion having an outer surface 47 that extends outward from spherical outer surface 44. This cylindrical portion may be used to enable the eyeball 43 to be mounted in a fixed position within the sleeve 30, such that the eyeball's outer surface 47 engaged with inner cylindrical surface 35 of the sleeve 30.
 Once the eyeball 43 has been properly positioned within the sleeve, the eyeball cover plate 50 may be installed over the eyeball. Eyeball cover plate 50 may comprise a cylinder, having a cylindrical inner surface 51, and a cylindrical outer surface 53, which are connected by an edge surface 52. Cylindrical outer surface 53 transitions, distally from the edge surface 52, into a curved front cover surface 54, which has a circular opening 55. The circular opening 55 may be sized so as to permit the eyeball 43 to protrude therefrom. In addition, the eyeball cover plate 50 may have a spherical inner surface 56, which is located between the circular opening 55 and the cylindrical inner surface 51. The spherical inner surface 56, once the eyeball cover plate 50 has been installed, will be flush against the spherical outer surface 44 of eyeball 43, so that the eyeball may be moveably positioned between the spherical inner surface 56 of eyeball cover plate 50 and the spherical inner surface 39 of the second cylinder 36 of the sleeve 30. With the eyeball cover plate 50 properly installed, the bi-fold split-disk butterfly valve 10 may appear as in FIG. 1, with the edge surface 52 of the eyeball cover plate 50 attached to the curved surface 20 of the face plate 19 of the housing 11.
 A pool may have a plurality of eyeball return fittings to accommodate the flow return from the filtering unit. The pool designer may thus opt to incorporate the eyeball fitting 10 with a bi-fold split-disk butterfly valve of the present invention into one or more of those fittings, and may do so according to a couple different methods, which may serve to improve pool surface water agitation to reduce settling of debris at low filter pump RPMs (revolutions per minute).
 In a first method, a series of first eyeball fittings 10P, which comprise eyeball fittings that are known in the prior art and therefore do not incorporate the split-disk bi-fold valve therein, may be located on one or more sidewalls of the pool, to thereby permit free return flow of filter pump water. (It should be noted that a pool may be comprised of one continuous curved wall, or one or more flat walls, or a combination therebetween). A series of second eyeball fittings 10V, which include the bi-fold split-disk butterfly valve disclosed herein, may be installed in the pool so as to be interspersed between the first eyeball fittings, as seen in FIG. 12.
 In normal operation of the pool filter with the pump operating at full speed (high RPMs), the flow rate would be sufficient to counter the biasing of the torsional spring 80 of bi-fold split-disk valve of eyeball fittings 10V, so that the demi-disks 71 would be open as in FIG. 6. In this case, return flow would be discharged from both the first eyeball fittings 10P and the second eyeball fittings 10V. When the filter pump is operated at a reduced speed (low RPMs), the resulting flow rate would be insufficient to overcome the biasing of the torsional spring 80 of valve 10, so that the demi-disks 71 would be biased closed, as seen in FIG. 5. In this instance, return flow would only be discharged from the first eyeball fittings 10P. The biasing capability of the spring 80 may thus being calibrated to selectively inhibit return flow from a particular filter pump that is pumping water at a "low" RPM setting. This "low" RPM value may be specific to a particular pool, as many in-ground pools are often custom designed according to the space available, the shape, or the length, width, and depth dimensions desired by the owner, etc, and may thus require a certain size filter pump. The pool designer may therefore need to adjust the spring constant, k (where for a spring, the deflection force is given by: F=-kx), for the spring 80 as required on a pool-by-pool basis.
 In this first method, the pool designer may opt to utilize the same spring stiffness for the torsional spring 80 in each of the eyeball return valves 10 in a particular pool installation. In this embodiment, during low speeds, all of the valves of eyeball fittings 10V would be closed and block the return flow, once the return flow fell to, or went below, a threshold flow rate.
 In an alternative method, for intermediate pump speeds (between high and low RPMs), the pressure force on the demi-disks from the flow rate may only be sufficient to cause the demi-disks to be partially biased back to the closed position, and may thus permit some water flow, and of course, at a high pump speed, the demi-disks would be fully open, while at low RPMs, the demi-disks would be fully closed.
 In yet another embodiment, the torsional capability (spring constant) of the helical spring 80 may be varied for different eyeball return fittings 10V that are utilized in a given pool installation to correspond to different flow rates of the variable speed filter pump. For example, a pool may utilize ten eyeball fittings, four of which may be the prior art eyeball fitting, 10P, and six of which may be the eyeball fitting of the current invention 10V. In this case, three of the six eyeball fittings 10V may have a higher spring constant, and thus may remain open when the filter pump is only reduced from high to mid-level RPMs, while the remaining three eyeball fittings with a lower spring constant are biased closed. When the filter pump is further reduced from mid-level RPMs to low RPMs, the three eyeball fittings 10V having the higher spring constant may also then bias its disks to be closed, so that filter return discharge is then only from the four prior art eyeball fittings 10P. Where multiple filter pump speeds are used (possibly a six-speed filter pump), it may be seen that torsion springs in each of the six (or alternatively a plurality of) second eyeball fittings may each comprises a unique spring constant, resulting in successive closing of second eyeball fittings across the six possible flow rates (or more generally, for a spectrum of flow rates).
 FIG. 12 illustrates installation, in a pool's sidewalls, of eyeball fittings 10P, and with installation of valved eyeball fittings 10V being interspersed therebetween, so that the eyeball fittings alternate peripherally around the pool (i.e., 10P, 10V, 10P, 10V . . .). Alternatively, other arrangements may be used, as seen in FIG. 12A, which may better serve to direct the surface agitation so as to produce current flows which direct the debris towards the pool's skimmer(s) 101.
 The examples and descriptions provided merely illustrate a preferred embodiment of the present invention. Those skilled in the art and having the benefit of the present disclosure will appreciate that further embodiments may be implemented with various changes within the scope of the present invention. Other modifications, substitutions, omissions and changes may be made in the design, size, materials used or proportions, operating conditions, assembly sequence, or arrangement or positioning of elements and members of the preferred embodiment without departing from the spirit of this invention.
Patent applications in class Including water inlet or outlet means
Patent applications in all subclasses Including water inlet or outlet means