Patent Abstract:
Valves, and particularly check valves, are detailed. The valves may isolate a spring or other biasing member from flowing fluid so as to reduce the possibility of damage to the spring caused, for example, by chemicals contained in the fluid. In some versions of the valves, the spring may be positioned within a cavity of a cover sealed from the fluid.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/295,221 filed on Jan. 15, 2010, and of allowed U.S. patent application Ser. No. 13/006,672 filed on Jan. 14, 2011, both entitled “Valves,” the contents of both of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to valves and more particularly, although not necessarily exclusively, to check valves designed to accommodate fluids having, e.g., low pH or high salt content. 
     BACKGROUND OF THE INVENTION 
     U.S. Pat. No. 6,247,489 to Maskell, et al., discloses an exemplary check valve especially useful as part of the water-recirculation system of a swimming pool, spa, or hot tub. The check valve includes a housing and a cover removably attached thereto. The housing may include coupling portions defining ports through which fluid may enter and exit the housing. 
     Pivotally attached to the cover of the check valve of the Maskell patent is a flapper assembly. The flapper assembly may comprise a diverter member having a body and two attachment arms. Pins are inserted through bores in the arms and the cover to attach the diverter member of the flapper assembly to the cover. 
     A spring (or other biasing member) may be positioned between the cover and the flapper assembly of the valve of the Maskell patent. The spring functions to bias the flapper assembly “into sealing engagement” with seats associated with the housing. Hence, when fluid flows through a conduit and into the entry port of the valve,
         it contacts the flapper assembly and pivots it to an open position . . . wherein fluid is permitted to enter the central area of the valve and exit through the [exit] port. However, should the fluid . . . be discontinued or otherwise attempt to flow out from the central area through the [entry] port, the flapper assembly is pivoted by virtue of contact with such fluid and by the biasing force of the spring [which] serves to bias [the flapper assembly] into contact with the seat to achieve a fluid-tight seal therebetween.
 
The contents of the Maskell patent are incorporated herein in their entirety by this reference.
       

     SUMMARY OF THE INVENTION 
     The check valve of the Maskell patent is a commercially useful product. However, when subjected to certain harsh environments, the valve may become less effective or fail sooner than desired. This is a particular risk when water flowing through the valve has low pH or high salt concentration, for example, as the water may cause pitting of the (typically stainless steel) biasing spring. 
     Accordingly, the present invention provides a check valve in which the biasing spring (which may be adjustable) is isolated from the flowing water. The valve may include a cover having a dry cavity in which the spring is positioned and a separate covering section for the cavity. Attachment arms of a diverter member (flapper) may receive a pivot pin to which a pivot link is pinned. Water-tight seals additionally may receive the pivot pin and prevent water from entering the cavity. Further, a bail may firmly receive ends of the pivot pin to facilitate transfer of motion of the flapper into extension of the spring. 
     The result is an assembly in which water flow against the (closed) flapper in one direction causes it to pivot against the bail (and thus to open), in turn causing rotation of the pivot pin. Rotation of the pivot pin, in its turn, causes rotation (or other movement) of the pivot link, which extends the biasing spring. Should the water flow cease (or reverse direction), the spring will tend to contract to its normal length and the flapper will return to its closed position. Alternatively, the assembly may be configured so that the flapper is normally open and closes as a function of water flow. 
     It thus is an optional, non-exclusive object of the present invention to provide a valve in which a biasing member is isolated from fluid flowing through the valve. 
     It is another optional, non-exclusive object of the present invention to provide a valve especially useful in certain harsh environments. 
     It is also an optional, non-exclusive object of the present invention to provide a check valve including a flapper configured to pivot about a pin. 
     It is a further optional, non-exclusive object of the present invention to provide a check valve in which a spring is positioned within a cover of the valve. 
     It is an additional optional, non-exclusive object of the present invention to provide a check valve in which a bail, attached to a pivot pin, facilitates transfer of motion of a flapper into extension or compression of a spring. 
     Other objects, features, and advantages of the present invention will be apparent to those skilled in the relevant art with reference to the remaining text and the drawings of this application. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  is a perspective, partially-exploded view of portions of a check valve of the present invention. 
         FIG. 2  is a perspective view of portions of a first alternate version of the check valve of  FIG. 1 . 
         FIGS. 3A-B  are perspective views of portions of a second alternate version of the check valve of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Illustrated in  FIG. 1  is cover  10  of an exemplary check valve of the present invention. Cover  10  may be similar to the covers described in the Maskell patent. Indeed, cover  10  may substitute for those covers if desired. In use, cover  10  is intended to be (removably) attached to a housing and, together with the housing, to form part of a valve assembly. 
     Cover  10  typically (although not necessarily) has generally circular cross-section with protrusions  14  extending outward about its periphery  18 . Consistent with the description in the Maskell patent, each protrusion  14  contains a bore  22  for receiving a screw or other fastener to attachment to the housing of the valve. 
     Again similar to the valve of the Maskell patent, that of the present invention may incorporate pin-receiving bores at or adjacent periphery  18  of cover  10 . Such bores receive pin  26 , connecting the pin  26  to cover  10 . Pin  26  preferably is cylindrical in central part  28 , albeit with D-shaped ends  30 . Pin  26  may, however, assume other shapes, as may its ends  30 . If ends  30  indeed are D-shaped, the flat portions of the “Ds” preferably face downward toward the housing when the valve is upright with cover  10  at its top. 
     Cover  10  may include cavity  34  in which (coil) spring  38  may be placed. A first end  42  of spring  38  may be anchored within cavity  34  in any suitable manner so that its second end  46  extends toward pin  26 . Rather than being connected directly to pin  26  outside cover  10 , however, second end  46  remains within cavity  34  and is connected to link  50 . Link  50 , in turn, is connected to central part  28  of pin  26  within cavity  34 . Annular (or other) seals  54  receive pin  26  to either side of link  50 , sealing boundaries of cavity  34  from fluid flowing through the valve. 
     Covering section  58  may function to cover cavity  34  to complete the isolation of spring  38  and link  50 . Section  58  preferably snap-fits onto cavity  34  to provide a generally continuous upper surface  62  of cover  10 . Section  58  may attach to cover  10  in other ways, however, if appropriate or desired. 
     Also illustrated in  FIG. 1  is bail  66 , preferably (although not necessarily) made of plastic or other non-metallic material. Bail  66  may comprise elongated central portion  70  from which legs  74 A and  74 B extend. Each leg  74 A and  74 B may define a D-shaped bore  78  adapted snugly to receive a corresponding D-shaped end  30  of pin  26 . 
     Finally, depicted in  FIG. 1  is flapper  82 , which may if desired be similar to the diverter member of the flapper assembly of the Maskell patent. Extending from flapper  82  are one or more arms  86 . In use, each arm  86  includes a bore  90  that receives pin  26 —preferably between a seal  54  and a leg  74 A or  74 B. 
     Flapper  82  typically is two-sided, with first side  94  shown in  FIG. 1 . Fluid impinging sufficiently on first side  94  will tend to rotate flapper  82  (generally “into” the paper of  FIG. 1 ) about pin  26  into an “open” position. This rotation itself may induce rotation of pin  26  depending on the amount of frictional contact between pin  26  and arms  86 . Otherwise, flapper  82  will rotate into contact with central portion  70  of bail  66 ; because of the keyed connection of D-shaped bores  78  and D-shaped ends  30 , such contact will cause bail  66  to induce rotation of pin  26 . In either circumstance (or via a combination of the two circumstances), rotation of pin  26  will cause movement of link  50 , which in turn will cause second end  46  to move away from first end  42 , hence extending spring  38 . Should the fluid impingement thereafter subside so as to be insufficient to overcome the contraction force of spring  38 , the spring  38  indeed will contract, moving link  50  and causing pin  26  to rotate in the opposite direction, and returning flapper  82  to the “closed” position illustrated in  FIG. 1 . In the “closed” position, flapper  82  generally is seated (as described, for example, in the Maskell patent) so as to preclude further rotation (i.e. “out of” the paper of  FIG. 1 ) and hence preclude any fluid impinging on the second side (not shown) of flapper  82  from exiting the valve via its entrance. 
       FIG. 2  illustrates cover  10  and spring  38  as part of a first alternate version of a check valve of the present invention. Second end  46  of spring  38  may be installed as shown in  FIG. 1 . First end  42 , however, may be moveable within cavity  34  so as to adjust the bias provided by spring  38 . One such movement means is depicted in  FIG. 2 : As shown, first end  42  connects to anchor  100 , whose position within rack  104  may be changed. Manual movement of anchor  100  between recesses  108 A-C of rack  104  thus changes the normal (resting) length of spring  38 , thereby changing the bias it may provide. Those skilled in the art will, of course, recognize that mechanisms other than as shown in  FIG. 2  may be employed to effect changes in bias. 
       FIG. 3B  illustrates cover  10  as well as anchor  100 , rack  104 , and recesses  108 A-C. Spring  38 ′ of  FIGS. 3A-B  is not an extension spring such as spring  38 , however. Instead, spring  38 ′ may be a compression spring. In this second alternate version of a check valve, the assembly may be reconfigured so that flapper  82  is normally open and designed to close as a consequence of sufficient fluid flow. 
     The assembly of the present invention thus provides a valve structure in which a biasing member, such as spring  38  or  38 ′, is isolated from fluid flowing through the valve. Although part of presently-preferred versions of the invention, bail  66  is optional and may, in some cases, be omitted. The foregoing thus is provided for purposes of illustrating, explaining, and describing embodiments of the present invention. Modifications and adaptations to these embodiments will be apparent to those skilled in the art and may be made without departing from the scope or spirit of the invention.

Technology Classification (CPC): 5