Abstract:
A diaphragm membrane ( 212 ) is disclosed that has a shape that spring loads a diaphragm during assembly to provide a default position for the diaphragm. The diaphragm membrane ( 212 ) is made from a resilient material. The diaphragm is spring loaded during assembly to provide a force that returns the diaphragm to the default position.

Description:
RELATED APPLICATIONS 
       [0001]    This application is related to applications “A rocker type diaphragm valve” and “A one piece double membrane diaphragm” filed on the same day as this application and hereby included by reference into this application. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention is related to the field of valves, and in particular, to an improved diaphragm valve. 
         [0004]    2. Description of the Prior Art 
         [0005]    Poppet valves can be stacked together to form control systems. The width of the poppet valve is typically known as the slice width Reducing the slice width allows more valves to be placed in the same amount of space. Some valves, for example a 5/2 mono-stable valve, require the valve to return to a default position in the absence of an activation force. The return force for the valve is typically supplied by a spring. Springs take up space. 
         [0006]    Therefore there is a need for a diaphragm poppet valve having a default position without requiring a separate spring. 
       SUMMARY OF THE INVENTION 
       [0007]    A diaphragm is disclosed that has a shape that spring loads the diaphragm during assembly to provide a default position for the diaphragm. The diaphragm is made from a resilient material. The diaphragm is spring loaded during assembly to provide a force that returns the diaphragm to the default position. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0008]      FIG. 1  is a cross sectional view of a typical prior art diaphragm valve  100 . 
           [0009]      FIG. 2  is an isometric sectional view of a diaphragm valve  200  in an example embodiment of the invention. 
           [0010]      FIG. 3  is an isometric sectional view of valve body  306  in an example embodiment of the invention. 
           [0011]      FIG. 4   a  is a top view of upper diaphragm membrane  412  in an example embodiment of the invention. 
           [0012]      FIG. 4   b  is a sectional view AA of upper diaphragm membrane  412  in an example embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0013]      FIGS. 2-4  and the following description depict specific examples to teach those skilled in the art how to make and use the best mode of the invention. For the purpose of teaching inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations from these examples that fall within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of the invention. As a result, the invention is not limited to the specific examples described below, but only by the claims and their equivalents. 
         [0014]      FIG. 1  is a cross sectional view of a typical 3/2 function diaphragm valve  100 . Diaphragm valve  100  comprises top plate  102 , bottom plate  104 , valve body  106 , top diaphragm membrane  108 , bottom diaphragm membrane  110 , top retaining ring  112 , bottom retaining ring  114 , spacer  116 , center spool  126 , upper sealing surface  120 , lower sealing surface  118 , inlet opening  122  and exhaust  124 . A diaphragm assembly is comprised of top diaphragm disk  108 , bottom diaphragm disk  110 , top retaining ring  112 , bottom retaining ring  114 , spacer  116  and center spool  126 . The parts in the diaphragm assembly are generally circular in nature and are symmetric about center line AA. Top plate  102  is attached to valve body  106  capturing top diaphragm disk  108  in a gap between the top plate  102  and valve body  106 . Bottom plate  104  is attached to valve body  106  capturing bottom diaphragm disk  110  in a gap between the bottom plate  104  and valve body  106 . Upper and lower sealing surfaces are generally circular in nature with each sealing surface formed in a plane. The sealing surfaces may also be called valve seats. The two planes containing the two sealing surfaces are generally parallel to each other. 
         [0015]    Valve  100  is shown in the off or closed position with top diaphragm disk  108  contacting upper sealing surface  120  and having a gap between bottom diaphragm disk  110  and lower sealing surface  118 . The gap between the bottom diaphragm disk  110  and the lower sealing surface is uniform in height. In the closed position fluid from an outlet opening (not shown) flows through the gap between the bottom diaphragm disk  110  and lower sealing surface  118  and out through exhaust  124  (as shown by arrow E). In the on position the central part of the diaphragm assembly is shifted upward such that the bottom diaphragm disk  110  contacts lower sealing surface  118  and a gap is formed between top diaphragm disk  108  and upper sealing surface  120 . The gap between the top diaphragm disk  108  and the upper sealing surface is uniform in height. In the on position, fluid flows from inlet opening  122  through the gap between top diaphragm disk  108  and upper sealing surface  120 , into an outlet opening (not shown). The two diaphragm disks flex or deform as the central part of the diaphragm assembly is shifted between the open and closed positions. There is generally radial symmetry in the deformation of the two diaphragm disks. The radial symmetry forms concentric circles of constant deflection in the two diaphragm disks. 
         [0016]      FIG. 2  is an isometric sectional view of a 3/2 function diaphragm valve  200  in an example embodiment of the invention. Diaphragm valve  200  comprises top plate  202 , bottom plate  204 , valve body  206 , upper diaphragm membrane  212 , lower diaphragm membrane  220 , spindle  210 , spindle cap  208  and spacer  218 . Top sealing surface  226  and bottom sealing surface  228  are formed in valve body  206 . In one example embodiment of the invention, each sealing surface is formed in one plane. Upper diaphragm membrane  212  has outer rim  214  attached to the outer edge of the diaphragm membrane and inner rim  216  attached to the inner edge of the diaphragm membrane. Lower diaphragm membrane  220  has outer rim  222  attached to the outer edge of the diaphragm membrane and inner rim  224  attached to the inner edge of the diaphragm membrane. The inner and outer rims on the two diaphragm membranes are optional. Other methods may be used to hold the diaphragm membranes into the valve or into the spindle. For example, a groove or channel may be formed in the outer edge of the diaphragm membrane and a lip or bead may be formed on the top plate that fits into the groove. A diaphragm assembly comprises the upper and lower diaphragm membranes ( 212  and  220 ), spindle  210 , spacer  218  and spindle cap  208 . The spacer is optional or may be integrated into spindle. 
         [0017]    To assemble the diaphragm assembly the upper diaphragm membrane  212  is inserted onto the spindle  210 . Spacer  218  is the inserted onto spindle  210 , capturing the inner rim  216  of upper diaphragm membrane between spindle  210  and spacer  218 . In one example embodiment of the invention, the spindle may be inserted into central opening  230  in valve body  206 . In other example embodiments of the invention, the diaphragm assembly may not be inserted into central opening  230  until fully assembled. Lower diaphragm membrane is now inserted onto spindle  210 . Spindle cap  208  is inserted onto, and attached to, spindle  210 , capturing inner rim  224  between spacer  218  and spindle cap  208 . 
         [0018]    When the diaphragm assembly is installed into diaphragm valve  200 , the two outer rims ( 222  and  214 ) are captured between the valve body and the upper and lower plates ( 202  and  204 ) respectively. In one example embodiment of the invention, the upper and lower outer rims seat into grooves formed into the top and bottom surfaces of the valve body  206 . In one example embodiment of the invention, top plate  202  and bottom plate  204  are attached to valve body  206  by laser welding. Other attachment methods may be used to attach the top and bottom plates to valve body  204 . 
         [0019]    In operation, diaphragm assembly moves between two positions, an upper position and a lower position. The deflection of diaphragm  228  is generally radially symmetric about the center of the diaphragm assembly. In the upper diaphragm position (not shown), lower diaphragm membrane  220  contacts and seals against the bottom sealing surface  228 . Upper diaphragm membrane  212  is positioned away from top sealing surface  226 , leaving a gap between the upper diaphragm membrane  212  and the top sealing surface  226 . The gap between the upper diaphragm membrane  208  and the top sealing surface  226  is generally a constant width (i.e. the gap is typically uniform). 
         [0020]    In the lower diaphragm position, upper diaphragm membrane  212  contacts and seals against the top sealing surface  226 . Lower diaphragm membrane  220  is positioned away from bottom sealing surface  228 , leaving a gap between the lower diaphragm membrane  220  and the bottom sealing sure  228 . 
         [0021]    Diaphragm assembly is typically moved between the upper position and the lower position using an activation force created by pressure from a pilot or control fluid (not shown). The control fluid is introduced into the gap between the upper diaphragm membrane  212  and the top plate  202  to force the diaphragm into the lower position. The control fluid is introduced into the gap between the lower diaphragm membrane  220  and the bottom plate  204  to force the diaphragm into the upper position. When there is no activation force applied to ether area, the diaphragm is configured to snap or return to a default position. The diaphragm may be configured such that the default position is either the upper diaphragm position or the lower diaphragm position. In some cases, the spring force may not be strong enough to return the diaphragm to the default position if the source supply is still active. Typically, the source supply is also used for the control supply, so when there is no pressure into the valve, both the control and the source will be inactive and the diaphragm will return to the default position. In one example embodiment of the invention, upper diaphragm membrane  212  is made from a resilient material, for example polyurethane, rubber, spring steel, or the like. The resilient material allows upper diaphragm membrane  212  to be assembled into the valve such that the resilient diaphragm material and the shape of upper diaphragm membrane  212  interacting with the valve body  206  and top plate  202  creates a spring force that returns the diaphragm to a default position. In another example embodiment of the invention, both the upper and lower diaphragm membranes are used to create the spring force. The lower diaphragm membrane would be made from a resilient material and also have a curved or bowl shape that would be aligned with the curved or bowl shape of the upper diaphragm membrane to help create a spring force when the diaphragm is installed into the valve. The method used to move the diaphragm between the upper and lower position is not important and other methods besides a pilot fluid may be used, for example a plunger activated by a coil and attached to the diaphragm. 
         [0022]      FIG. 3  is an isometric sectional view of valve body  306  in an example embodiment of the invention. Valve body  306  forms three ports or openings, port  322 , port  328  and port  324 , top sealing surface  320  and bottom sealing surface  318 . Depending on the configuration of the valve, the ports may be used as an inlet port, an outlet port, or an exhaust port. When a diaphragm (not shown) is in the upper position, fluid enters port  322 , flows over the top of top sealing surface  320  between a gap formed between the upper diaphragm membrane and the top sealing surface, and then flows into port  328 . When the diaphragm (not shown) is in the lower position, fluid exits port  328 , flows underneath the bottom sealing surface  318  between the gap formed between the lower diaphragm membrane and the bottom sealing surface  318 , and then flows into port  324 . 
         [0023]      FIG. 4  is a drawing of an upper diaphragm membrane  412  in an example embodiment of the invention. In one example embodiment of the invention, upper diaphragm membrane  412  is a generally circular part. In other example embodiments of the invention, the upper diaphragm membrane  412  may be oval or rectangular in shape. Other shapes are also possible.  FIG. 4   a  is a top view of upper diaphragm membrane  412  in an example embodiment of the invention. 
         [0024]      FIG. 4   b  is a sectional view AA of upper diaphragm membrane  412  in an example embodiment of the invention. Upper diaphragm membrane  412  comprises an outer rim  414 , an inner rim  416  and a diaphragm membrane  411  having a thickness t. The outer rim  414  is configured to fit into a gap between the top plate and the valve body of the valve. The outer rim helps hold the diaphragm assembly in place in the valve and create a seal between the diaphragm assembly and the valve. Diaphragm membrane  411  is coupled to outer rim  414  along the inner diameter of outer rim  414 . Diaphragm membrane  411  is coupled to inner rim  4416  along the outer diameter of inner rim  414 . Upper diaphragm membrane  412  is made from a resilient material, for example rubber, polyurethane, spring steel, or the like. Outer rim  414  is formed essentially in one plane shown as AA. Inner rim  416  is formed in essentially one plane shown as BB that is offset, but generally parallel to plane AA. The offset between the inner rim and the outer rim, the diaphragm membrane thickness t, and the diaphragm material generate the force that returns the diaphragm assembly to the first, or default, position when the diaphragm assembly is installed into the valve.