Abstract:
A check valve for placement in a fluid conduit, includes a separator element with at least one opening; the opening allows fluid flow through the separator element. A pliant sealing member is attached to a downstream side of the separator element, covering the opening. During forward flow, this pliant sealing member deforms, allowing fluid to pass around it. However, during reverse fluid flow, this pliant sealing member flattens and covers the opening, preventing reverse fluid flow through the opening.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application Serial No. 60/161,526, filed Oct. 26, 1999, and U.S. Provisional Application Serial No. 60/183,262, filed Feb. 17, 2000. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to check valves, and, in particular, to inversion resistant check valves. 
     2. Description of the Prior Art 
     A check valve is essentially a valve which allows fluid to flow in only one direction through a conduit, while closing and preventing back or reverse flow, when back pressure builds up downstream of the valve to a level greater than the upstream fluid pressure head. 
     Check valves are used in various fluid transportation operations and must include some means of allowing the forward flow of liquid yet preventing any back flow. Further, it is desirable to have maximum flow at the lowest possible pressure drop in the forward direction of flow, commonly referred to as headloss. It is also necessary to provide some means for resisting collapse under the back pressure or reverse flow of the fluid. 
     As demonstrated in U.S. Pat. No. 5,769,125 to Duer et al., a check valve may employ a hinge and trough construction, which is an inversion deterrent. Further, as seen in U.S. Pat. No. 5,848,605 to Bailey et al., a spring and poppet mechanism may be utilized to allow forward fluid flow, while, at the same time preventing back flow. Still another example of a check valve with back flow prevention is disclosed in U.S. Pat. No. 5,947,152 to Martin et al. In this patent, a resilient seal ring is used to engage opposed walls of the valve body, allowing forward fluid flow and preventing back flow. 
     While all of the prior art uses some form of mechanism to prevent back flow, most of the previously mentioned patents are unable to withstand very high back pressure. Further, the prior art that discusses intricate mechanical devices to prevent back flow and inversion are cost prohibitive in many situations. Still further, the prior art, which does provide increased inversion protection, does so at the cost of pressure drop in the forward direction of flow. This headloss degrades the flow pattern and velocity in the valve mechanism, decreasing efficiency. 
     It is, therefore, an object of this invention to provide a check valve that overcomes the design problems encountered in the prior art. It is another object of this invention to provide high inversion resistance during high back pressure situations, in a much more cost-effective manner. It is also an object of the present invention to allow smooth fluid flow in the forward direction, with little headloss through the valve. 
     SUMMARY OF THE INVENTION 
     The present invention is a check valve for placement in a fluid conduit including a separator element having at least one opening to allow fluid flow through the separator element. A pliant sealing member is attached to one side of the separator element, covering the separator element opening. This pliant sealing member is configured to deform during forward fluid flow, allowing fluid to pass around the pliant sealing member, and to flatten during reverse fluid flow, covering the opening. In this manner, reverse fluid flow is prevented from entering the opening. 
     In operation, the fluid flow of liquid enters the check valve area, passes through the opening of the separator element, deflecting the pliant sealing member forward. The fluid passes around the separator element and exits, continuing through the fluid conduit. When back flow is encountered, the pliant sealing member is “flipped” backwards, returning to its flat, undeflected state and engaging the separator element. Once in this state, the pliant sealing member effectively blocks the opening in the separator element, preventing passage of liquid in the reverse direction. The invention also includes a method of conveying fluid and preventing reverse fluid flow in a conduit. 
     The invention itself, both as to its construction and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a side sectional view of a first embodiment of the present invention; 
     FIG. 2 shows a front view of the separator element; 
     FIG. 3 a  shows a front view of a pliant sealing member according to a second embodiment of the present invention; 
     FIG. 3 b  shows a side sectional view of the pliant sealing member of FIG. 3 a  taken along line A—A; 
     FIG. 4 shows a perspective view of a pliant sealing member and separator element according to a third embodiment of the present invention; 
     FIG. 5 a  shows a perspective view of a pliant sealing member and a separator element according to a fourth embodiment of the present invention; 
     FIG. 5 b  shows a perspective view of a pliant sealing member and a separator element according to a fifth embodiment of the present invention; 
     FIG. 6 shows a side sectional view of a sixth embodiment of the present invention; 
     FIG. 7 shows a side exploded sectional view according to a seventh embodiment of the present invention; 
     FIG. 8 shows a front view of the separator element according to the seventh embodiment of the present invention; 
     FIG. 9 shows a front view of a separator element according to an eighth embodiment of the present invention; 
     FIG. 10 shows a front view of a further embodiment of the openings of the separator element according to the eighth embodiment of the present invention; and 
     FIG. 11 shows a front view of a further embodiment of the openings of the separator element according to the eighth embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention is a check valve  10  with primary application in the area of large diameter “clean” water usage operations. While check valve  10  is typically used in “inline” configurations, in a preferred embodiment, as shown in FIG. 1, the present invention check valve  10  comprises an inlet body half  12  connected to an outlet body half  14 . Both the inlet body half  12  and the outlet body half  14  can be constructed of metal or plastic materials, selected to be compatible with the process fluid and pressure requirements. The inlet body half  12  begins with an inlet flange  16  which diverges and terminates in an inlet body flange  20 . The outlet body half  14  begins with an outlet body flange  22 , converges and terminates in an outlet flange  18 . The inlet body half  12  is connected to the outlet body half  14  via the inlet body flange  20  and the outlet body flange  22 . Further, it is contemplated that suitable gaskets may be required to provide a fluid-tight seal. Inlet flange  16  and outlet flange  18  are provided so that the check valve  10  may be connected to a piping system in a conventional manner. 
     Clamped between the inlet body flange  20  and the outlet body flange  22  is a separator element  24  bisecting the check valve  10 . Any fluid that enters the inlet body half  12  must necessarily encounter the separator element  24 . Additionally, the separator element  24  must have at least one passage  26  in order for fluid to flow through the separator element  24 . In the preferred embodiment, the separator element  24  has multiple separator element passages  26 . These passages  26  can be of unlimited shapes and patterns (as long as fluid flow is acceptable and the structural integrity of the separator element  24  is not compromised), and FIG. 2 illustrates a typical separator element  24  design. 
     A pliant sealing member  28  is attached to the center of the separator element  24  via a retaining element, for example, retaining bar  30 . The retaining bar  30  is secured to the separator element  24  by a retaining nut  32 , fastening the pliant sealing member  28  at its center to the separator element  24 . 
     In operation, fluid flows through a piping system inlet pipe into the check valve  10 . Initially, the fluid enters the inlet body half  12 , encountering the separator element  24  and passing through the separator element passages  26 . As fluid contacts the pliant sealing member  28 , the pliant sealing member  28  is deflected forward into the outlet body half  14 . The fluid continues by and around the now deflected pliant sealing member  28 , through the outlet body half  14  and into a piping system outlet pipe. If back pressure and back flow arises, the fluid flow reverses, flattening the pliant sealing member  28  flush against the separator element  24 . In this manner, the separator element passages  26  are fully covered by the pliant sealing member  28  and reverse flow is stopped. Overall, using the check valve  10  in this operation will allow forward flow and disallow reverse flow of the process fluid. This invention is particularly useful in larger diameter applications, for example 48-inch or 60-inch water lines operating with high back pressures. 
     Since high back pressure may, in some instances, extrude the pliant sealing member  28  back through the separator element passages  26 , one or more plies of a reinforcing layer, such as fabric, nylon, polyester or Kevlar®, can be included in the construction of the pliant sealing member to strengthen the pliant sealing member  28 . Constructed with low durometer elastomer reinforced with plies, the pliant sealing member  28  can be made both strong enough to resist high back pressure, and, at the same time, pliable enough to provide excellent sealing at the separator element  24 . 
     A second embodiment is illustrated in FIGS. 3 a  and  3   b . The overall invention and operation of the second embodiment is identical as hereinabove described. However, in this embodiment, an inner surface of the pliant sealing member  28  is formed with a seal  34 , typically an integral O-ring, around the outside diameter of the pliant sealing member  28 . During reverse fluid flow, the seal  34  engages the separator element  24  and provides a substantially fluid-tight seal between the pliant sealing member  28  and the separator element  24 . The integral O-ring  34  is molded on the pliant sealing member  28  and engages the outer periphery of the separator element  24  in order to provide a secondary sealing area against the separator element  24 , when back flow conditions are present. 
     A third embodiment is illustrated in FIG.  4 . In this embodiment, the check valve  10  is identical as hereinabove described, however, the retaining bar  30  extends vertically, bisecting the pliant sealing member  28 . The retaining bar  30  is still utilized to secure the pliant sealing member  28  against the separator element  24 , but also serves to reinforce the pliant sealing member  28 , preventing sagging during periods of no flow. This retaining bar  30  may be made of any suitable cross-sectional shape; it may be hollow or solid. Further, the retaining bar  30  can be made with metal bar or rubber, allowing “give” to the rubber membrane and enhancing life under flow conditions. 
     It is envisioned that the retaining bar  30  may also comprise at least three arms extending centrally from the pliant sealing member  28 . For example, in a fourth embodiment, as shown in FIG. 5 a , the retaining bar  30  may consist of three connected equilaterally-spaced bars extending from the center point of the pliant sealing member  28 . This embodiment would provide even further support to the pliant sealing member  28  during periods of no flow. In addition, this embodiment may be particularly useful in large diameter pipe applications. 
     In a fifth embodiment, as shown in FIG. 5 b , the retaining bar  30  may consist of four connected equilaterally-spaced bars, extending from the center point of the pliant sealing member  28 . The retaining bar  30  thus resembles a cruciform. This embodiment would provide still further support to the pliant sealing member  28  during periods of no flow. Additionally, this embodiment may also be utilized in large diameter pipe applications. In addition, this embodiment is preferred when the invention is oriented in a horizontal manner (i.e., with the piping system running vertically), with the pliant sealing member  28  on the underside of the separator element  24 . Using this embodiment of the retaining bar  30  prevents the pliant sealing member  28  from flipping and remaining in the open position due to gravity. 
     A sixth embodiment is illustrated in FIG. 6, which is particularly adapted for smaller diameter pipeline applications. In this embodiment, the inlet body half  12  terminates with inlet body pipe threads  38 . Likewise, the outlet body half  14  begins with outlet body pipe threads  40  which are constructed to mate with the inlet body pipe threads  38 . The inlet body half  12  begins with the inlet pipe threads  42  and the outlet body half  14  ends with the outlet pipe threads  44 . Both the inlet pipe threads  42  and the outlet pipe threads  44  are utilized to connect the check valve  10  to a smaller diameter pipe system. 
     In this sixth embodiment, the separator element  24  is directly attached to (or integrally formed with) the end of the inlet body half  12 . The pliant sealing member  28  is attached to the center of the separator element  24  via a retaining screw  36 . In operation, this embodiment is identical to the invention as hereinabove described. The threaded connections promote more secure and economical usage of the invention in small diameter pipe applications. 
     A seventh embodiment is illustrated in FIG. 7, which demonstrates another inline application of the present invention  10 . Pipe flanges  46  are secured together using bolt mechanisms  54  around the perimeter. Attached directly between these pipe flanges  46  is a separator element  24  with separator element passages  26 . On both sides of the separator element  24  and around the perimeter are circular support plate O-ring grooves  52 . As seen in FIG. 8, the support plate O-ring grooves  52  are particularly adapted to receive support plate O-rings  50 , which seal the separator element  24  between the pipe flanges  46 . 
     Also, as seen in this embodiment, the separator element passages  26  may be arranged so as to leave solid, unopened areas  56  in the separator element  24  (shown in FIG.  8 ). These solid, unopened areas  56  add strength to the separator element  24 . Further, the solid, unopened areas  56  create an overall stronger valve. After assembly, the pliant sealing member  28  (not shown) is attached to the downstream side of the separator element  24  via the retaining bar  30  and retaining nut  32  (not shown). In operation, this embodiment operates as hereinabove described. Further, this seventh embodiment is more cost-effective in its manufacture. 
     Three variations of the separator element  24 , according to an eighth embodiment of the invention, are illustrated in FIGS. 9-11. As seen in these variations, the placement of the separator element passages  26  on the separator element  24  can be drilled so as to provide the aforementioned solid, unopened areas  56 . These solid, unopened areas  56  promote a stronger separator element  24 . So as not to produce too much pressure drop across the valve, these solid, unopened areas  56  can directly correspond to the geometric shape of the retaining bar  30 . For example, the retaining bar  30  of the fourth embodiment consists of three connected equilaterally-spaced bars, extending from the center point of the pliant sealing member  28 . So, for the fourth embodiment, as illustrated in FIG. 9, the solid, unopened areas  56  would correspond directly to the shape of the retaining bar  30 . Likewise, the solid, unopened areas  56  can correspond to each geometric shape of the retaining bar  30 . These solid, unopened areas  56 , while slightly increasing the pressure drop, greatly increase the strength of the separator element  24  and, in turn, the valve  10 . 
     Overall, the present invention creates an efficient and durable inversion resistant check valve  10  with high back pressure capability and low pressure drop in the forward direction. Further, the present invention is cost-effective and particularly adapted to large diameter pipe applications. 
     It will be evident to those of ordinary skill in the art that various changes and modifications may be made to the present invention without departing from the spirit and scope thereof. The specific embodiments described herein are intended to be illustrative of, and not restrictive of, the present invention. This invention has been described with reference to the preferred embodiments. Obvious modifications and alterations will occur to others upon reading and understanding the detailed description.