VALVE WITH A SPRINGY DIAPHRAGM

RELATED APPLICATIONS

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

1. FIELD OF THE INVENTION The invention is related to the field of valves, and in particular, to an improved diaphragm valve.

2. DESCRIPTION OF THE PRIOR ART

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.

Therefore there is a need for a diaphragm poppet valve having a default position without requiring a separate spring.

SUMMARY OF THE INVENTION

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

FIG. 1 is a cross sectional view of a typical prior art diaphragm valve 100. FIG. 2 is an isometric sectional view of a diaphragm valve 200 in an example embodiment of the invention.

FIG. 3 is an isometric sectional view of valve body 306 in an example embodiment of the invention.

FIG. 4a is a top view of upper diaphragm membrane 412 in an example embodiment of the invention.

FIG. 4b is a sectional view AA of upper diaphragm membrane 412 in an example embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Figures 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. Figure 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.

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.

Figure 2 is an isometric sectional view of a 3/2 iunction 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 Up 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.

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.

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.

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).

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 surface 228.

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.

Figure 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.

Figure 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. Figure 4a is a top view of upper diaphragm membrane 412 in an example embodiment of the invention.

Figure 4b 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 X, 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.