Abstract:
A check valve is provided for stopping the reverse flow of fluid through a fluid-carrying conduit and includes a fluid dampening device to dampen the closing movement of the valve upon flow reversal. The fluid dampening device includes a member for containing a fluid that becomes compressed upon a reverse flow of fluid through a conduit that houses the check valve. As the check valve is forced by a reverse fluid flow in a reverse direction, fluid in the fluid dampening device becomes compressed and is permitted to slowly seep out of the fluid dampening device via fluid passageways that permit only the slow escape of fluid from a compressed fluid chamber.

Description:
BACKGROUND 
     The present invention relates to a check valve for shutting off the reverse flow of fluid through a conduit upon a fluid flow reversal event. 
     A common problem with existing check valves is that upon flow reversal, as can occur in fluid flow systems, the check valve slams shut. The slamming action of the valve and repeated slamming can damage the valve and prevent the valve from operating properly. A need exists for a check valve that can stop the reverse flow of fluid through a fluid carrying conduit without causing damage to the valve or to the conduit. It would be desirable to provide a check valve that does not slam shut upon reverse flow conditions in a fluid carrying conduit but instead is provided with a dampening feature to allow a smooth and non-damaging closing movement of the valve upon reverse fluid flow. 
     SUMMARY OF THE INVENTION 
     The present invention provides a check valve for allowing the flow of fluid through a fluid-carrying conduit in a normal, forward direction, and for preventing the reverse flow of fluid in a reverse direction. The check valve of the present invention is designed such that upon a reversal of fluid flow through a conduit in which the check valve is employed, the closing movement of the valve is dampened and does not slam shut. 
     This objective is achieved according to the present invention by providing a check valve that includes a sealing device, a guide plate, and a valve plate with a dampening chamber wherein the sealing device includes a sealing plate, a guide shaft, and a dampening shaft that cooperates with the dampening chamber. The sealing plate is adapted to seal one or more through-passages in the valve plate that allow the flow of fluid through the valve plate. The guide shaft extends from a first surface of the sealing plate and is adapted for reciprocating guided movement within a guide aperture of the guide plate. The guide plate is adapted to be positioned within a fluid-carrying conduit and has one or more through-passages for allowing the flow of fluid through the guide plate. Preferably, the guide aperture is centrally located through the guide plate and guides the reciprocating movement of the guide shaft. The dampening shaft extends from a second surface of the sealing plate that is opposite the first surface. The dampening shaft is adapted for reciprocating movement within the dampening chamber of the valve plate. 
     The valve plate is adapted to be positioned within a fluid-carrying conduit and has one or more through-passages for allowing the flow of fluid through the valve plate. A seat is provided surrounding the through-passages of the valve plate and is designed for contacting the second surface of the sealing device to prevent the flow of fluid through the through-passages of the valve plate. The dampening chamber receives the dampening shaft and is adapted for providing a fluid cushioning of the dampening shaft as the dampening shaft moves into the dampening chamber, as occurs upon a reversal of fluid flow through the fluid-carrying conduit. At least one of the dampening shaft and the dampening chamber includes a choke bore for preferably allowing the slow escape of compressed fluid from the dampening chamber upon movement of the dampening shaft into the dampening chamber. The dampening shaft, dampening chamber, and choke bore are respectively dimensioned such that when the guide plate, sealing device, and valve plate are operably positioned within a fluid-carrying conduit, and the dampening shaft is forced into the dampening chamber, fluid within the dampening chamber becomes compressed and escapes through the choke bore at a rate that is sufficiently slow to dampen the movement of the dampening shaft into the dampening chamber. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are only intended to provide a further explanation of the present invention, as claimed. The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate several exemplary embodiments of the present invention and together with description serve to explain the principles of the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention may be more fully understood with reference to the accompanying figures. The figures are intended to illustrate exemplary embodiments of the present invention without limiting the scope of the invention. 
     FIG. 1 is a cut-away view of a section of pipe containing therein a check valve, shown in partial cross section and in partial phantom view, according to an embodiment of the present invention; 
     FIG. 2 is a cut-away view of the section of pipe shown in FIG. 1 wherein the check valve of the present invention is in a partially closed position; 
     FIG. 3 is a cut-away view of the section of pipe shown in FIG. 1 wherein the check valve of the present invention is in a fully closed position; 
     FIG. 4 is a top plan view of the valve seat disk shown in the embodiment of the present invention depicted in FIG. 1; and 
     FIG. 5 is a top plan view of the valve guide plate shown in the embodiment of the present invention depicted in FIG.  1 . 
    
    
     DETAILED DESCRIPTION 
     The check valve of the present invention provides a dampening closing movement of a sealing device upon reverse fluid flow conditions in a fluid-carrying conduit. The dampened movement prevents a slamming action of the sealing device when the check valve is closed. The present invention provides the dampened action by a check valve design that includes a sealing device, a guide plate, and a valve plate, wherein the sealing device includes a sealing plate, a guide shaft, and a dampening shaft. All components are preferably made of durable, non-corrosive materials such as metal or hard plastic or the like. Aluminum and stainless steel are preferred materials for the check valve components. 
     The sealing device includes a sealing plate that is preferably disk-shaped, though other shapes can be used. The guide shaft and the dampening shaft of the sealing device are preferably cylindrical shafts that preferably extend perpendicularly from opposite first and second surfaces of the sealing plate. Again, other shapes can be used. The sealing plate is adapted to seal one or more through-passages in the valve plate that allow the flow of fluid through the valve plate. The sealing plate, guide shaft, and dampening shaft of the sealing device can be integrally formed or molded, welded, or otherwise connected together after being separately made. The guide shaft and dampening shaft can be continuous with one another, for example, in the form of a continuous shaft or dowel, and the sealing plate can be a ring with a hole in the middle through which one of the guide shaft and dampening shaft is slipped and then connected. The sealing plate can then be mounted to the shaft at about a midpoint to form the sealing device. 
     The guide shaft preferably extends through a guide aperture of the guide plate. Preferably, the guide aperture of the guide plate is formed in a central location of the guide plate and has a diameter that is slightly larger than the outer diameter of the guide shaft. The guide shaft, or reciprocating shaft, is preferably guided in its reciprocating motion by the guide aperture of the guide plate. 
     The dampening shaft preferably extends directly opposite the guide shaft, and extends from the second surface of the sealing plate. The dampening shaft is adapted for reciprocating movement within a dampening chamber or fluid cushioning chamber of the valve plate. The valve plate is adapted to be positioned within a fluid-carrying conduit and to have one or more through-passages for allowing a flow of fluid through the valve plate. A seat, provided on a top surface of the valve plate that faces the guide plate, surrounds the one or more through-passages in the valve plate and is designed for contacting the second surface of the sealing device or sealing plate so that, upon contact, the flow of fluid through the through-passages of the valve plate is prevented. 
     The dampening chamber is preferably positioned in a central location of the valve plate and is preferably aligned with the guide aperture of the guide plate. The dampening chamber, also referred to as a fluid cushioning chamber, preferably comprises a cup-shaped member having a hollow cylindrical sidewall and a bottom wall. The dampening chamber could be mounted or formed in a separate plate or disk separate from said valve plate. The dampening chamber receives the dampening shaft and at least one of the dampening shaft and the dampening chamber is provided with a choke bore for allowing the escape of fluid at a limited rate from the dampening chamber as the dampening shaft moves into the dampening chamber. The dampening shaft, dampening chamber, and choke bore are respectively dimensioned such that, in operation, when the sealing plate and associated guide shaft and dampening shaft move in a closing direction, the dampening shaft is forced into the dampening chamber and fluid within the dampening chamber becomes compressed and escapes the dampening chamber through the choke bore at a rate that is sufficiently slow so as to dampen the movement of the dampening shaft into the dampening chamber. 
     Referring now to the drawing figures, FIG. 1 shows a section of pipe  10  containing therein a check valve  12  according to an embodiment of the present invention. The check valve  12  includes a sealing device  13 , a guide plate  20 , and a valve plate  40 . In the embodiment shown in FIG. 1, the sealing device  13  is not shown in cross-section. The sealing device includes a sealing means such as a sealing plate  14  fastened, secured, mounted, integrally formed with, fixed, or otherwise secured to a guide shaft or reciprocating shaft  16 , and a dampening shaft  17 . The reciprocating motion of guide shaft  16  is guided by a guide means such as a shaft guide ring  18  preferably integrally formed at an inner, central portion of the guide plate  20 . A TEFLON® ring or other type of bushing can be provided between guide shaft  16  and guide shaft ring  18 . Guide plate  20  is mounted within pipe section  10  by spot weld beads  22  and is configured such that the outer diameter of guide plate  20  is the same as the inner diameter of the pipe section  10 . The outer diameter of guide plate  20  is defined by another ring  23  as is best seen in FIG.  5 . Shaft guide ring  18  has an inner diameter that is substantially the same as, although preferably slightly larger than, the outer diameter of guide shaft  16  to enable a guided reciprocating motion of guide shaft  16  substantially free of frictional interference between the shaft guide ring  18  and the guide shaft  16 . 
     Preferably, the guide plate  20  and valve plate  40  have shapes that match the inner shape of the conduit  10  in which they are mounted, for example, circular in the embodiment shown. Preferably, the sealing plate, guide plate, and valve plate are each symmetrically shaped, for example, each are circular or disk-shaped. 
     The guide plate  20  and valve plate  40  can alternatively be integrally formed, for example, cast, with sections of pipe that can later be assembled and connected with the sealing device  13  placed between the plates. 
     The guide shaft  16  extends from a top surface  15  of sealing plate  14 . The dampening shaft  17  extends from a bottom surface  19  of sealing plate  14 , preferably directly opposite the guide shaft  16 . The reciprocating motion of dampening shaft  17  is guided by the motion of a sealing ring  24  mounted, secured, or otherwise fixed to dampening shaft  17  at a lower end of dampening shaft  17 . The sealing ring  24  is preferably made of a material exhibiting lubricity, such as a TEFLON® material, and may be made of a conventional bushing material. The reciprocating motion of dampening shaft  17  is guided by the motion of sealing ring  24  along an inner wall  26  of a dampening means such as a fluid cushioning or dampening chamber  28 . Further, details of guide plate  20  and valve plate  40  are shown in FIGS. 5 and 4, respectively. 
     The fluid cushioning or dampening chamber  28  is defined by a cup-shaped member  30  having a sidewall  32  and a bottom wall  34 . Provided in the sidewall  32  of cup-shaped member  30  is a bleed hole  36  for allowing the passage of air or fluid from said fluid cushioning or dampening chamber  28  to the interior space  38  of the pipe section  10 . The cup-shaped member  30  that defines fluid cushioning or dampening chamber  28  is preferably mounted to the central portion of a flow-through valve plate  40  that is secured to the inner wall of pipe section  10 , for example, by beads of welding material  42  welded to an outer ring  47 . Also mounted, secured, or otherwise fixed to flow-through valve plate  40  is a seat means such as a sealing plate seat  44  that extends from an upper surface  46  of flow-through valve plate  40 . Sealing plate seat  44  is ring-shaped and provides a through-passage  48  through the inner portion thereof. The sealing plate seat may be integrally formed, for example, cast, with the valve plate  40  or it may be made separately and then fixed or otherwise connected to the valve plate  40 . The seat  44  is preferably made of a non-corrosive material and can be made of a rubber or plastic material, such as TEFLON®, adhered to the valve plate  40 . Through-passage  48  communicates with one or more through-passages  50  formed through the flow-through valve plate  40 . 
     Dampening shaft  17  is provided with one or more bore holes  52 , shown in phantom in FIG.  1 . Preferably, the bore hole  52  is a radial bore hole. Bore hole  52  communicates with an axial bore  54  also shown in phantom in FIG.  1 . Axial bore  54  is preferably formed in the lower end of dampening shaft  17  and extends upward through a central portion of dampening shaft  17  to an intersection with bore hole  52 . Thus, a passage is formed from the side of dampening shaft  17  into dampening shaft  17  and out through the lower end thereof. 
     In operation, fluid flows through pipe section  10  in the direction shown by arrows A. A fluid, such as air, flows from section  56  of pipe section  10  through through-passages  50  and  48 , respectively, into section  58  of pipe section  10 . From pipe section  58 , the fluid flows through one or more through-passages  21  formed in guide plate  20  and into pipe section  60 . The flow of fluid through pipe section  10  typically also includes a flow of fluid into bore hole  52 , through axial bore  54 , into fluid cushioning or dampening chamber  28 , and out bleed hole  36 . The flow of fluid through pipe section  10  urges the sealing plate  14  and its connected guide shaft  16  in an upward open direction in the view shown in FIG. 1, against the force of a biasing element  80  in the form of a helical spring that urges the sealing plate in a closed direction. The upward movement of the sealing plate  14  and guide shaft  16  can be limited by an advancement restraining device such as a spring, mechanical stop, or other device that limits the movement of the sealing plate  14  in the direction of the flow of fluid. 
     Referring now to FIG. 2, wherein reference numerals that are the same as used in FIG. 1 represent the same respective components. Upon a reversal of the direction of fluid flow through pipe section  10 , as shown by flow directional arrows B, sealing device  13  begins to close and is shown in a partially closed position. As can be seen in FIG. 2, the sealing ring  24  disposed at the lower end of dampening shaft  17  has moved passed bleed hole  36  in the sidewall  32  of cup-shaped member  30  that defines the dampening chamber  28 . As a result, fluid trapped within the bottom portion of fluid cushioning chamber  28  cannot escape through bleed hole  36  because sealing ring  24  forms a seal between the outside of shaft  16  and the inner surface of sidewall  32 . As a result of the sealing function of sealing ring  24 , the only escape route for fluid trapped within dampening chamber  28  is through axial bore  54  and out bore hole  52 . As a result, the rate of escape of fluid from dampening chamber  28  slows after the sealing ring  24  moves into dampening chamber  28  past bleed hole  36 , relative to the rate of escape upon the initial closing movement. Preferably, the diameter of at least one of axial bore  54  and bore hole  52  is smaller than the diameter of bleed hole  36 . Preferably, at least one of axial bore  54  and bore hole  52  is sufficiently small such that fluid in dampening chamber  28  becomes compressed due to the downward motion of dampening shaft  17  and sealing ring  24 . Preferably, the compression of fluid in dampening chamber  28  is significant enough and/or the rate of escape of fluid from dampening chamber  28  is slow enough, to cushion, dampen, or slow the advancement of dampening shaft  17  and the connected sealing plate  14  in the downward direction, thereby preventing a slamming action of sealing plate  14  against the top surface  45  of sealing plate seat  44 . 
     Referring now to FIG. 3, wherein reference numerals identical to those used in FIGS. 1 and 2 depict identical perspective components to those shown in FIGS. 1 and 2, the reverse motion of sealing device  13  has been completed and the sealing plate  14  is seated against the top surface  45  of seat  44 . In the fully closed positioned shown, the flow of fluid through through-passages  48  and  50  has ceased and the reverse flow of fluid through pipe section  10  has ceased. The sealing plate  14 , guide shaft  16 , and dampening shaft  17  will remain in the closed positions shown in FIG. 3 until a forward flow of fluid, as depicted in FIG. 1, resumes through pipe section  10 . 
     FIG. 4 shows a top plan view of the flow-through valve plate  40 , including the sealing plate seat  44  and the cup-shaped member  30  shown in FIGS. 1-3. As can be seen in FIG. 4, the flow-through disk  40  is made of a solid material such as metal, and has through passages  48 ,  50  through a substantially central portion thereof. The cup-shaped member  30  can be seen in the central portion of the flow-through valve plate  40  including the sidewall  32  and the bottom wall  34 . The sealing plate seat  44 , as shown, constitutes a ring-shaped protrusion extending from the top surface  46  of the flow-through valve plate  40 . The top surface  45  of the sealing plate seat  44  provides a flat sealing surface for contacting the sealing plate  14  (not shown in FIG.  4 ). The cup-shaped member  30  is secured to the flow-through valve plate  40  by three mounting brackets  64 ,  66 ,  68 , as shown in FIG.  4 . The mounting brackets  64 ,  66 , and  68  can be welded, integrally formed with, or otherwise, fixed, mounted, or secured to flow-through valve plate  40 , preferably by a suitable method recognized by those skilled in the art. Mounting brackets  64  and  66  are not shown in the cross sectional view of flow-through valve plate  40  depicted in FIGS. 1-3 and mounting bracket  68  is hidden from view by dampening shaft  17  and cup-shaped member  30 . 
     FIG. 5 is a top plan view of the guide plate  20  shown in FIGS. 1-3. As shown in FIG. 5, the guide plate  20  includes guide member  18  in the form of a ring mounted in a central portion of the guide plate  20 . The guide member  18  is connected to an outer ring  23  of guide plate  20  by mounting brackets  70 ,  72 , and  74 . Mounting brackets  70 ,  72 , and  74  can be welded, integrally formed with, or otherwise mounted, fixed, or secured to the centrally located guide member  18  and the outer ring  23  in any suitable manner recognized by those skilled in the art. In the cross sectional view of guide plate  20  shown in FIGS. 1-3, mounting brackets  70  and  72  are not shown and mounting bracket  74  is hidden from view by a top portion of guide member  18 . 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments of the present invention without departing from the spirit or scope of the present invention. Thus, it is intended that the present invention cover other modifications and variations of this invention within the scope of the appended claims and their equivalents.