Abstract:
A check valve including a cylindrical valve well defining a chamber, a valve disk, a pin centrally connecting the valve well to the valve disk; the valve disk being axially symmetrically positioned with respect to the valve well. The valve disk forms a fluid seal with an annular rim of the valve well when a first pressure acting on the valve disk is greater that a opposing second pressure within the chamber. The check valve further includes a plurality of vanes disposed within the chamber, where the vanes prevent the valve disk from collapsing into the chamber due to an excessive first pressure on the valve disk.

Description:
BACKGROUND 
       [0001]    The present disclosure relates generally to check valves and more particularly to a check valve utilized in a printing device. 
         [0002]    Check valves are widely used in industries for controlling the flow of fluids. They are frequently used together with a variety of mechanical pumps to prevent back flow of fluids from the pump to the fluid original supply. Use of check valves in this manner ensures that sudden changes in pressure at a delivery end of the pump does not result in contamination of the fluid supply. Check valves of the variety which utilizes a valve disk are simple in design and widely used in printing devices. However, due to their simple design, they are often prone to failure when subjected to excessive pressures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]    For a detailed description of exemplary embodiments of the invention, reference will now be made to the accompanying drawings in which: 
           [0004]      FIG. 1  illustrates a block diagram of a simplified system deploying a prior art check valve; 
           [0005]      FIG. 2  shows a partially cross-sectioned prior art check valve; 
           [0006]      FIG. 3  shows a side view of a cross sectioned prior art check valve; 
           [0007]      FIG. 4  shows a partially cross-sectioned check valve of a present embodiment; 
           [0008]      FIG. 5  shows a side view of a cross sectioned check valve of a present embodiment; 
           [0009]      FIG. 6  shows a side view of a cross sectioned check valve of a present embodiment; and 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    An embodiment of a simplified printing system  5  such as an inkjet printer is generally depicted in  FIG. 1 . The simplified printing system  5  generally comprises an ink supply  2 , and an ink jet print head  7 . Ink is delivered to the ink jet print head  7  by a pump  3  drawing ink from the ink supply  2 . The pump  3  may be any of a variety of mechanical or electromechanical pumps and can be a generic diaphragm pump. A check valve  10  prevents any ink pumped out from the pump  3  from flowing back into and contaminating the ink supply  2 . 
         [0011]      FIG. 2  shows an example of a general prior art check valve  10 . Such a check valve  10  comprises a cylindrical valve well  30 , a circular valve disk  40  and a pin  50 . The pin  50  serves to connect the valve disk  40  securely to the valve well  30 . 
         [0012]    The valve well  30  includes an internal wall  32  and an internal floor  34 . The internal wall  32  and the internal floor  34  in combination defines a chamber of the valve well  30 . 
         [0013]    The valve disk  40  is axially symmetrically positioned with respect to the valve well  30  and is kept in position by the pin  50 . 
         [0014]    When a pressure P 1  which is greater than an opposing pressure in the chamber, is exerted on the valve disk  40 , the valve disk  40  is actively in a closed position. In the closed position, the valve disk  40  is seated on an annular rim  36  of the valve well  30 . The valve disk  40  in the closed position forms a fluid seal with the annular rim  36 . This prevents any fluid in the chamber of the valve well from escaping via spaces between the valve well  30  and the valve disk  40 . 
         [0015]    The valve disk  40  is formed from a flexible resiliently deformable material and is of a larger diameter than the annular rim  36 . When pressure P 1  is the same as the pressure in the chamber, the valve disk  40  is passively in a closed position and seated on the annular rim  36 . 
         [0016]    In operation, when P 1  is lower than the opposing pressure in the chamber of the valve well  30 , the valve disk  40  is actively in an open position. 
         [0017]    The valve disk  40  flexes away from the annular rim  36  of the valve well  30  allowing fluid to escape via space between the valve disk  40  and the annular rim  36  of the valve well  30 . 
         [0018]    In  FIG. 3 , when pressure P 1  on the valve disk  40  is excessively high, the valve disk  40  being made from a flexible resiliently deformable material may flex inwards into the chamber of the valve well  30 . If the pressure P 1  is too high, a portion of the valve disk  40  may flex to a point where that portion of the valve disk  40  collapses into the chamber of the valve well  30  as shown in  FIG. 3 . 
         [0019]    While the valve disk  40  is generally designed to have a greater diameter than the annular rim  36 , excessive pressure P 1  on the valve disk  40  causes it to flex until the edge  42  of the valve disk  40  collapses into the chamber. In addition to the edge  42  of the valve disk  30  collapsing into the chamber, the edge  42  is further caught up against the internal wall  32 . This further prevents the valve disk  40  from recovering to its uncollapsed position. Such a collapse of the valve disk  40  can be catastrophic as no amount of corresponding pressure will be able to restore the valve disk  40  to its uncollapsed condition. 
         [0020]      FIG. 4  shows a check valve  10 A in accordance with a present embodiment. The check valve  10 A similarly comprises a cylindrical valve well  30 , a circular valve disk  40  and a pin which connects the valve disk  40  to the valve well  30 . The valve well  30  includes an internal wall  32  and an internal floor  34  which in combination defines a chamber. The valve disk  40  is similarly axially symmetrically positioned with respect to the valve well  30  and is kept in position by the pin  50 . 
         [0021]    The check valve  10 A further comprises a plurality of vanes  60  disposed within the chamber of the valve well  30 . 
         [0022]    The vanes  60  extend radially from a circumference of the internal well  32  into the chamber of the valve well  30 . The vanes  60  are substantially arranged in a well spaced out manner along the circumference. In an example, the number of vanes may number between 3 to 6. 
         [0023]    In  FIG. 5 , the vanes  60  when viewed from a side view are substantially in a convex configuration and extend from the internal wall  32  to the internal floor  34 . The convex configuration is not a limitation and those skilled in the art will appreciate that the vanes may be practised in a variety of configurations. 
         [0024]    The valve disk  40  typically has a diameter which is greater than the diameter of the annular rim  36 . This feature helps to prevent the valve disk  40  from collapsing into the chamber. However in the event excessive pressure is encountered, the valve disk  40  may still collapse into the chamber as shown in  FIG. 3 . 
         [0025]    In  FIG. 5 , a profile of the valve disk  40  when in a passively closed position is represented by x. When experiencing excessive pressure, the valve disk  40  deforms and flexes to a profile represented by y 2 . This amount of flex is minimal and permits the valve disk  40  to recover to its original profile once the pressure eases. The profile y 2  is made possible by the valve disk  40  being supported by the plurality of vanes  60 . The vanes  60  are designed to minimize flexing of the valve disk into the chamber under pressure by supporting the valve disk  40  from inside the chamber. 
         [0026]    However, in a situation where the plurality of vanes  60  is absent, the valve disk  40  may collapse to a profile as represented by y 1  and as an example may be illustrated in  FIG. 3 . With a collapse to a profile of y 1 , the valve disk  40  may be damaged and will unlikely to recover to its earlier profile of x. 
         [0027]    The plurality of vanes  60  in the check valve  10 A of the embodiment, prevents the valve disk  40  from collapsing into the chamber. In  FIG. 6 , even with excessive pressure P 1  on the valve disk  40 , the valve disk  40  is supported by the vanes  60  from inside the chamber and slides on the vanes  60  but cannot collapse into the chamber. In particular, the edge  42  of the valve disk  40  is further prevented from collapsing into the chamber or from getting caught on the internal wall  32  of the valve well  30 . 
         [0028]    Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. In addition, certain additional operational details and features of the check valve  10  known to those skilled in the art which do not have bearing on the current embodiments have not been discussed in detail.