Patent Publication Number: US-2011061750-A1

Title: Check valve counterbalanced by flow to control opening and closing speed

Description:
BACKGROUND OF THE INVENTION 
     This application relates to a check valve which pivots about an axis which is offset from a center of the check valve disc in two directions. 
     Check valves are known, and utilized in many fluid flow applications. Essentially, a check valve allows flow of a fluid in one direction, but is forced to a sealing position if flow moves in the opposed direction. 
     In one known type of check valve, a disc pivots about an axis, from a first sealing position at which the disc seats on a valve seat, and to an open position. If such a disc valve pivots about an axis which extends through a center of the disc, then the fluid forces acting on the disc to open or close the disc will be balanced. The speed of movement to the open position can thus only be controlled by the force of the fluid. 
     It has been proposed to move the hinge axis off of the center line of the disc. In this manner, fluid forces acting on the disc on opposed sides of the hinge axis are unequal, and thus the fluid forces on the two sides of the axis can be controlled to control the opening and closing speed by selecting the amount of offset. 
     Still, there are deficiencies in the proposed check valve. 
     Various other offset angled valves are known, and have been used in particular in butterfly valves. Butterfly valves are typically driven by a motor, and thus, the challenges mentioned above with regard to a check valve are not as applicable. 
     SUMMARY OF THE INVENTION 
     A check valve has a valve seat defining an inner peripheral bore. A valve disc is positioned within said inner peripheral bore, and mounted for pivotal movement about a hinge axis. A first central plane separates the valve disc along a diameter, and a second central plane dividing the valve disc along a thickness. The hinge axis is offset from both of the central planes. 
     These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross sectional view through a first check valve embodiment. 
         FIG. 2  shows the  FIG. 1  check valve in an open position. 
         FIG. 3  is a perspective view of a valve disc according to this invention. 
         FIG. 4  is a cross-sectional view showing yet another feature. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A check valve  20  is illustrated in  FIG. 1  for being mounted within a pipe or conduit  22 . As illustrated in this Figure, a valve seat within the conduit  22  has an angled portion  41 , and a cylindrical portion  43 . The entire surface of the valve seat, beyond these two singular points will be best understood from  FIG. 4 . A valve disc  26  has a surface  40  mating with the angled point  41 , and a cylindrical portion  25 . 
     The valve disc  26  pivots about a hinge axis  28  mounted within an ear  30  for defining the axis  28 . As can be appreciated, a central plane P of the disc  32 , defined through a thickness, is offset from the hinge axis  28  by a distance d 1 . As can also be seen in  FIG. 1 , the hinge axis  28  is offset from a center plane C, defined by a diameter, of the valve disc  26  by a second distance d 2 . The d 2  offset provides the benefit of allowing the fluid flow to be controlled to control the opening and closing speed. As can be appreciated from  FIG. 1 , there will be greater valve force to the right-hand side (area  34 ) of the hinge axis  28  as illustrated in this Figure than to the left (area  32 ), and this will allow the speed of the valve opening to be controlled. That is, by selecting a desired offset d 2 , the speed of opening of the valve at any given pressure of fluid expected to pass through the conduit  22  can be controlled. 
     The offset d 1  moves the hinge axis away from the sealing seal as the hinge pin will increase the difficulty of providing sealing. 
     As shown in  FIG. 2 , a stop  100  will stop movement of the valve disc  26 . In this stopped position, the valve disc will be held against the stop. 
     As can appreciated, the stop pin  100  is positioned such that a flat face  110  on the ear  30  contacts the stop pin to prevent further movement of the valve disc  32 . This will avoid transmitting the loads through stress concentrations in the valve disc. 
     As can be appreciated from  FIG. 4 , the valve seat surface  100  is defined by a conical surface which is centered about an axis x. The axis x is offset from a center axis y of the duct  22  by an angle A. The angle A may be between 20° and 30°. As can be appreciated from  FIG. 4 , the angled surface  43  is positioned on one side of the valve seat  100 , while at a diametrically opposed location is the angled surface  41 . The angled surface  41  is at an angle equal to angle A. Between points  43  and  41 , in both circumferential directions, the angle of the valve seat increases progressively and at a constant rate from the cylindrical surface  43  to the angle A at  41 . 
     Although an embodiment of this invention have been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.