Title of Invention	CATHODES FOR ALUMINIUM ELECTROLYSIS CELL WITH NON-PLANAR SLOT DESIGN
Abstract	Abstract CATHODES FOR ALUMINIUM ELECTROLYSIS CELL WITH NON-PLANAR SLOT DESIGN Cathodes for aluminium electroiysis cells containing of cathode blocks and current collector bars attached to those blocks whereas the cathode slots receiving the collector bar have a higher depth at the center than at both lateral edges of the cathode block. Additionaliy, the collector bar thickness is higher at the center than at both lateral edges of the cathode block. This cathode design provides a more even current distribution and, thus, a longer useful lifetime of such cathodes and increased cell productivity.

Title of Invention

CATHODES FOR ALUMINIUM ELECTROLYSIS CELL WITH NON-PLANAR SLOT DESIGN

Abstract

Abstract CATHODES FOR ALUMINIUM ELECTROLYSIS CELL WITH NON-PLANAR SLOT DESIGN Cathodes for aluminium electroiysis cells containing of cathode blocks and current collector bars attached to those blocks whereas the cathode slots receiving the collector bar have a higher depth at the center than at both lateral edges of the cathode block. Additionaliy, the collector bar thickness is higher at the center than at both lateral edges of the cathode block. This cathode design provides a more even current distribution and, thus, a longer useful lifetime of such cathodes and increased cell productivity.

Full Text	The invention is related to the field of valves, and in particular, to an improved diaphragm valve. Diaphragm valves typically use a double membrane diaphragm design. Double membrane diaphragm designs typicall; contain a top and bottom diaphragm membrane attached to a central spindle and held in place by a top and bottom retaining part. The central spindle may also be fabricated from a number of parts. Each interface between the different parts is a potential leak point for the valve. The large number of parts needed for each diaphragm may increase manufacturing cost and inventory cost. THerefore there is a need for a doUBLEe membrane diaphragm fabricaRed in one piece, SUMMARY OF THE INVENTION A one piece double membrane diaphragm is disclosed. The double membrane diaphragm has an upper and lower diaphragm membrane joined together by a central section. The upper diaphragm membrane is configured to seal against a top sealing surface when the diaphragm is in a first position. The lower diaphragm membrane is configured to seal against a bottom sealing surface when the diaphragm is in a second position. An upper rim may be attached to the upper diaphragm membrane where the upper rim is configured to help hold the upper diaphragm membrane into the valve. A lower rim may be attached to the lower diaphragm membrane where the lower rim is configured to help hold the lower diaphragm membrane into the vaive. The diaphragm may also be made from a resilient materia] and shaped in such a way as to create a spring force holding the diaphragm into a default position in the valve. 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 a drawing of diaphragm 328 in an example embodiment of the invention. FIG- 4 is a flow chart for assembling a diaphragm valve 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 ait 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 diaphragm valve 1 00. Diaphragm valve 100 comprises top plate i 02. bottom plate 104. valve body 106. top diapln-agm disk 108. bottom diaphragm disk 110. top retaining ring 112. bottom retaining ring 114. spacer I ] 6, 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 A.A. Top plate 102 is attached to vaK'e body 106 capturing top diaphragm disk ! 08 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 ] GO is shown in the offer 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 iower 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 ! 10 and lower sealing surface 11 8 and out through exhaust 124 {as shown by arrovv E). In the on position the centra) pan of the diaphragm assembJy is shifted upward such thai 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 ) 08 and the upper sealing surface is uniform in height. In flie 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. In different valve configurations, the inlet opening 122 may be used as an exhaust port and the exhaust 124 may be used as an inlet opening. Figure 2 Is an isometric sectional view of a diaphragm valve 200 in an example embodiment of the invention. Diaphragm \alve 200 comprises top plate 202. bottom plate 204. valve body 206 and diaphragm 228. Diaphragm 228 has upper diaphragm membrane 205. lower diaphragm membrane 210. center section 212. upper rim 218, iower rim 220, top stiffener 214 aNd bottom sliffener 216. Diaphragm 228 is fabricated as one piece. In one example embodiments diaphragm 228 is generally circular in shape. In other example embodiments of the invention, diaphragm 228 may be oval or rectangular in shape. In one example embodiment of the invention, diaphragm 228 is molded. In another example embodiment of the invention, diaphragm 228 is machined from a block of material. Diaphragm 228 is fabricated from a resilient material or a combination of resilient materials, for example rubber, polyurethane. or the like. The upper diaphragm membrane 208 and lower diaphragm membrane 210 are joined together by the central diaphragm section 212. In one example embodiment of the invention, diaphragm 228 is symmetric with respect to axis AA. Top stiffener 214 is formed on the top side of upper diaphragm membrane and configured to stiffen upper diaphragm membrane. Bottom stiffener 216 is formed on the bottom side of lower diaphragm membrane and configured to stiffen lower diaphragm membrane. Top and bottom stiffeners (2 i 4 and 2 ] 6) may nol be needed and are optional. A top sealing surface (also called a top valve seat) 222 and bottom sealing surface (also called a bottom valve seat) 224 are formed in valve body 206. In one example embodiment of the invention, each sealing surface or valve seat is formed in one plane. The top sealing surface 222 and the bottom sealing surface 224 generally surround a central opening 240 in the valve body 206. In one example embodiment of the invention, the planes containing the top and bottom valve seats are generally parallel to each other. In another example embodiment of the invention, the planes containing the top and bottom valve seats are generally not parallel to each other. Top plate 202 is attached to valve body 206. capturing upper diaphragm membrane 208 in a gap between top plate 202 and valve body 206. Bottom plate 204 is attached to valve body 206. captui'ing lower diaphragm membrane 210 in a gap between bottom plate 204 and valve body 206. in one example embodiment of the invention, top plate 202 and bottom plate 204 are attached to valve body by laser welding. Any other attachment method may be used to attach the top and bottom plates to valve body 204. In one example embodiment of the invention, top rim 218 is formed around the outer edge of upper diaphragm membrane 208 and is configured to fit into a groove formed between the top plate 202 and the top side of valve body 206. Top rim 218 holds upper diaphragm membrane in place and forms a seal between the diaphragm and the valve. Bottom rim 220 is foimed around the outer edge of lower diaphragm membrane 210 and is configured lo fit into a groove formed between the bottom plate 204 and the bottom side of valve body 206. Bottom rim 220 holds lower diaphragm membrane in place and forms a seal between the diaphragm and the valve. The top and bottom rims on the two diaphragm membranes are optional. Other methods may be used to hold ihe diaphragm membranes into the valve. 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. In operation, diaphragm 228 moves between two positions, an upper position and a lower position. The deflection of diaphragm 228 is generally radially symmetric about the center of diaphragm 228 (axis AA). In the upper diaphragm position (not shown), lower diaphragm membrane 210 contacts and seals against the bottom sealing surface 224. Upper diaphragm membrane 208 is positioned away from top sealing surface 222. leaving a gap between the upper diaphragm membrane 208 and tHe lop sealing surface 222. In the lower diaphragm position, upper diaphragm membrane 208 contacts and seals against the top sealing surface 222. Lower diaphragm membrane 210 is positioned away from bottom sealing surface 224. leaving a gap between the lower diaphragm membrane 210 and the bottom sealing surface 224. Diaphragm 228 is typically moved between the upper position and the lower position using an activation force created by pressure from a pilot fluid (not shown). The pilot fluid is introduced into the gap betw'een the upper diaphragm membrane 208 and the top plate 202 to force diaphragm 228 into the lower position. The pilot fluid is introduced into the gap between the lower diaphragm membrane 210 and the bottom plate 204 to force diaphragm 228 into the upper position. When there is no activation force applied to ether area, diaphragm 228 may be configured to snap or return to a default position. The diaphragm 228 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, botli the control and the source will be inactive and the diaphragm will return lo the default position. The method used to move the diaphragm between the upper and lower position is not imponant and other methods besides a pilot fluid may be used, for example a plunger activated by a coil and attached to the diaphragm. In one example embodiment of the invention, diaphragm 228 is made from a resilient material, for exainple polyurethane. The resilient material allows diaphragm 228 to be assembled into the valve such that the resilient diaphragm maierial and the shape of diaphragm 228 interacting with the valve enclosure creates a spring force that returns diaphragm 228 to a default position. In one example embodiment of the invention, the upper diaphragm membrane 208 has a bowl or dish shape such that when the diaphragm is installed into the valve, the upper diaphragm membrane forces the diaphragm into the lower position when there is no pressure into the valve. In another example embodiment of the invention, both the upper and lower diaphragm membranes have a bowl or dish shape such that when the diaphragm is installed into the valve, the two diaphragm membranes forces the diaphragm into the lower position. Figure 3 is a drawing of diaphragm 328 in an example embodiment of the invention. Figure 3a is a top view of diaphragm 328. in an example embodiment of the invention. Figure 3b is a sectional view AA from top view 3a, in an example embodiment of the invention. Diaphragm 328 comprises upper diaphragm membrane 308. lower diaphragm membrane 310, center section 312, upper rim 318 and lower rim 320. In one example embodiment, diaphragm 328 is generally circular in shape. In other example embodiments of the invention, diaphragm 328 may be ovai or rectangular in shape. Other shapes are also possible. Upper diaphragm membrane 308 is attached to lower diaphragm membrane 310 by center section 31 2 that holds the two diaphragm membranes in a spaced apart relationship, in one example embodiment of the invention, upper diaphragm membrane is generally parallel with lower diaphragm membrane 310. In another example embodiment of the invention, upper diaphragm membrane is not parallel with lower diaphragm membrane 310. In one example embodiment of the invention the upper and lower rims are generally circular in shape. In other example embodiments of the invention, the rims may be oval or rectangular in shape. The upper and lower rims (31 S and 320) are configured to fit into a gap between the top plate and the valve body and the bottom plate and the valve body. The rims help hoid diaphragm 328 in place in the valve and create a seal between diaphragm 328 and the valve. The upper and lower rims on the two diaphragm membranes are optional. Other methods may be used to hold the diaphragm membranes into the valve. For example, a groove or channel may be formed in the outer edge of tlie diaphragm membrane and a lip or bead may be formed on the top plate or on the valve bod\' that fits into the groove. Upper diaphragm membrane 308 is coupled to upper rim 318 along the inner diameter of upper rim 318. Lower diaphragm membrane 310 is coupled to lower rim 320 along the inner diameter of lower rim 320. Diaphragm 328 is fabricated in one piece. Upper diaphragm membrane 308 has thickness t. Upper diaphragm membrane 308 has a bowl or dish shape. The outer edge of upper diaphragm membrane 308 is fomied in essentially one plane shown as BB. The inner part of upper diaphragm membrane 308, where it joins with the central section 312. is formed in essentially one plane as shown by CC. Plane CC is offset, but generally parade! to plane BB. The offset between the inner and th*e outer areas of upper diaphragm membrane, 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. In one example embodiment of the invention, lower diaphragm membrane also has a dish or bowl shape that is aligned in the same direction as the dish or bowl shape of the upper diaphragm membrane, in other example embodiments of the invention, lower diaphragm membrane may be flat or ha-ve a bowl shape that is not aligned with the upper diaphragm membrane. Figure 4 is a flow chart for assemblingg a diaphragm valve in an example embodiment of the invention- At step 402 the upper diaphragm membrane is compressed. At step 404 the compressed upper membrane is inserted through the central opening in the valve body. At step 406 the compressed upper diaphragm membrane is released such that the valve body is captured between the upper diaphragm membrane and the lower diaphragm membrane with the center section of the diaphragm located in the central opening in the valve body. Either the upper diaphragm membrane or the lower diaphragm membrane can be compressed and insened through the central opening in the valve body. At optional step 408. an upper and lower rim is seated into an upper and lower groove respectively, where the upper and lower grooves are formed into a top and bottom surface of the valve body. At step 410 atop plate is attached to the top surface of the valve body holding the upper diaphragm membrane between the top plate and the valve body. At step 4) 2 a bottom plate is attached to the bottom surface of the valve body holding the lower diaphragm membrane between the bottom piate and the valve body. CLAIMS: (1) Cathode 1 for aluminium electraiysis ce«5 comprising a csrtior or graphite cathode block 4 with a collector bar slot 3 receiving one or two steel-made current collector bars 2, cfiaracterized in that the depth of slot 3 Is higher at the center C than at both lateral edges of cathode block 4. {2) Cathode 1 according to claim 1, characlerized ir that the collector bar slot 3 has a triangular, semi-circular or semi-eliipsojdal shape- (3) Cathode 1 according to Glaims 1 or 2, characterized in that the collector bar slat 3 comprises one or more steps. (4) Cathode 1 according to one of the claims 1 to 3, characterized in that the collector bar slot 3 has an initial planar top face at both lateral block adges stretching over 10 to 1000 mm from each edge. (5) Cathode 1 according to to ons of the claims 1 to 4, characterized in that the thickness of the one or two collector bars 2 is higher at higher at the center C than at tfoih lateral edges of cathode block 4. {6} Cathode 1 according to claim 5, characlerized in that the thickness of the one or two collector bars 2 is increased exclusively at the face facing the slot 3 top face. (7) Cathode 1 according to dalms 5 or 6, characterized in that the one or two collector bars 2 have a triangular, semi-circular QT semi-ellipsoidal sdape. (8) Cathode 1 according to one of the claims 5 to 7, characterized in that the the thickness of the one or twa collector bars 2 comprises Increases by one or more steps. (9) Cathode 1 according to one of the claims 5 to S, characterized in that the one or two collector bars 2 have at least one steel plate 9 attached to it (10) Cathode 1 according to claim 9, characterized In that resilient graphite foil is placec between the at least one steel plala 9 and steel collector bar 2 as well as between each subsequently attached steal piale 9, {11} Cathode 1 according to ona of the claims 1 to 10 having more (han one collector bar slot 3. (12) Method of manufacturing cathodes 1 for aluminium electrolysis cells, characterized by the steps - manufacturing a carbon or graphite cathode block 4 with standard External dimensions, ■ machining at feasf one collector bar slot 3 with iacreasing depfli towards the cathode block center C, fitting at least one steel collector bar 2 Info each of the at least one slots 3, (13) Method of manufacturing cathodes 1 for aluminium electrolysis cells, characterized by the steps - manufacturing a carbon or graphite cathode bioci dimensions. machining at least one collBctor bar slot 3 with increasing depth towards the cathode blocic center C, fitting at least one steel collector bar 2 with Increasing thickness at the face facing the col lector bar slot 3 top face towards its center C into each of the atieastoneslotsS. (14} Aluminium electrolysis celis containing cathodes 1 according to one of the claims 1 to 11.

Full Text

The invention is related to the field of valves, and in particular, to an improved diaphragm valve.
Diaphragm valves typically use a double membrane diaphragm design. Double membrane diaphragm designs typicall; contain a top and bottom diaphragm membrane attached to a central spindle and held in place by a top and bottom retaining part. The central spindle may also be fabricated from a number of parts. Each interface between the different parts is a potential leak point for the valve. The large number of parts needed for each diaphragm may increase manufacturing cost and inventory cost.
THerefore there is a need for a doUBLEe membrane diaphragm fabricaRed in one piece,
SUMMARY OF THE INVENTION
A one piece double membrane diaphragm is disclosed. The double membrane diaphragm has an upper and lower diaphragm membrane joined together by a central section. The upper diaphragm membrane is configured to seal against a top sealing surface when the diaphragm is in a first position. The lower diaphragm membrane is configured to seal against a bottom sealing surface when the diaphragm is in a second position. An upper rim may be attached to the upper diaphragm membrane where the upper rim is configured to help hold the upper diaphragm membrane into the valve. A lower rim may be attached to the lower diaphragm membrane where the lower rim is configured to help hold the lower diaphragm membrane into the vaive. The diaphragm may also be made from a resilient materia] and shaped in such a way as to create a spring force holding the diaphragm into a default position in the valve.
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 a drawing of diaphragm 328 in an example embodiment of the invention.
FIG- 4 is a flow chart for assembling a diaphragm valve 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 ait 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 diaphragm valve 1 00. Diaphragm valve 100 comprises top plate i 02. bottom plate 104. valve body 106. top diapln-agm disk 108. bottom diaphragm disk 110. top retaining ring 112. bottom retaining ring 114. spacer I ] 6, 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 A.A. Top plate 102 is attached to vaK'e body 106 capturing top diaphragm disk ! 08 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 ] GO is shown in the offer 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 iower 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 ! 10 and lower sealing surface 11 8 and out through exhaust 124 {as shown by arrovv E). In the on position the centra) pan of the diaphragm assembJy is shifted upward such thai 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 ) 08 and the upper sealing surface is uniform in height. In flie 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. In different valve configurations, the inlet opening 122 may be used as an exhaust port and the exhaust 124 may be used as an inlet opening.
Figure 2 Is an isometric sectional view of a diaphragm valve 200 in an example embodiment of the invention. Diaphragm \alve 200 comprises top plate 202. bottom plate
204. valve body 206 and diaphragm 228. Diaphragm 228 has upper diaphragm membrane
205. lower diaphragm membrane 210. center section 212. upper rim 218, iower rim 220, top stiffener 214 aNd bottom sliffener 216. Diaphragm 228 is fabricated as one piece. In one example embodiments diaphragm 228 is generally circular in shape. In other example embodiments of the invention, diaphragm 228 may be oval or rectangular in shape. In one example embodiment of the invention, diaphragm 228 is molded. In another example embodiment of the invention, diaphragm 228 is machined from a block of material. Diaphragm 228 is fabricated from a resilient material or a combination of resilient materials, for example rubber, polyurethane. or the like.
The upper diaphragm membrane 208 and lower diaphragm membrane 210 are joined together by the central diaphragm section 212. In one example embodiment of the invention, diaphragm 228 is symmetric with respect to axis AA. Top stiffener 214 is formed on the top side of upper diaphragm membrane and configured to stiffen upper diaphragm membrane. Bottom stiffener 216 is formed on the bottom side of lower diaphragm membrane and configured to stiffen lower diaphragm membrane. Top and

bottom stiffeners (2 i 4 and 2 ] 6) may nol be needed and are optional. A top sealing surface (also called a top valve seat) 222 and bottom sealing surface (also called a bottom valve seat) 224 are formed in valve body 206. In one example embodiment of the invention, each sealing surface or valve seat is formed in one plane. The top sealing surface 222 and the bottom sealing surface 224 generally surround a central opening 240 in the valve body 206. In one example embodiment of the invention, the planes containing the top and bottom valve seats are generally parallel to each other. In another example embodiment of the invention, the planes containing the top and bottom valve seats are generally not parallel to each other.
Top plate 202 is attached to valve body 206. capturing upper diaphragm membrane 208 in a gap between top plate 202 and valve body 206. Bottom plate 204 is attached to valve body 206. captui'ing lower diaphragm membrane 210 in a gap between bottom plate 204 and valve body 206. in one example embodiment of the invention, top plate 202 and bottom plate 204 are attached to valve body by laser welding. Any other attachment method may be used to attach the top and bottom plates to valve body 204. In one example embodiment of the invention, top rim 218 is formed around the outer edge of upper diaphragm membrane 208 and is configured to fit into a groove formed between the top plate 202 and the top side of valve body 206. Top rim 218 holds upper diaphragm membrane in place and forms a seal between the diaphragm and the valve. Bottom rim 220 is foimed around the outer edge of lower diaphragm membrane 210 and is configured lo fit into a groove formed between the bottom plate 204 and the bottom side of valve body 206. Bottom rim 220 holds lower diaphragm membrane in place and forms a seal between the diaphragm and the valve. The top and bottom rims on the two diaphragm membranes are optional. Other methods may be used to hold ihe diaphragm membranes into the valve. 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.
In operation, diaphragm 228 moves between two positions, an upper position and a lower position. The deflection of diaphragm 228 is generally radially symmetric about the center of diaphragm 228 (axis AA). In the upper diaphragm position (not shown), lower diaphragm membrane 210 contacts and seals against the bottom sealing surface 224. Upper diaphragm membrane 208 is positioned away from top sealing surface 222. leaving a gap between the upper diaphragm membrane 208 and tHe lop sealing surface 222. In the lower

diaphragm position, upper diaphragm membrane 208 contacts and seals against the top sealing surface 222. Lower diaphragm membrane 210 is positioned away from bottom sealing surface 224. leaving a gap between the lower diaphragm membrane 210 and the bottom sealing surface 224.
Diaphragm 228 is typically moved between the upper position and the lower position using an activation force created by pressure from a pilot fluid (not shown). The pilot fluid is introduced into the gap betw'een the upper diaphragm membrane 208 and the top plate 202 to force diaphragm 228 into the lower position. The pilot fluid is introduced into the gap between the lower diaphragm membrane 210 and the bottom plate 204 to force diaphragm 228 into the upper position. When there is no activation force applied to ether area, diaphragm 228 may be configured to snap or return to a default position. The diaphragm 228 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, botli the control and the source will be inactive and the diaphragm will return lo the default position. The method used to move the diaphragm between the upper and lower position is not imponant and other methods besides a pilot fluid may be used, for example a plunger activated by a coil and attached to the diaphragm.
In one example embodiment of the invention, diaphragm 228 is made from a resilient material, for exainple polyurethane. The resilient material allows diaphragm 228 to be assembled into the valve such that the resilient diaphragm maierial and the shape of diaphragm 228 interacting with the valve enclosure creates a spring force that returns diaphragm 228 to a default position. In one example embodiment of the invention, the upper diaphragm membrane 208 has a bowl or dish shape such that when the diaphragm is installed into the valve, the upper diaphragm membrane forces the diaphragm into the lower position when there is no pressure into the valve. In another example embodiment of the invention, both the upper and lower diaphragm membranes have a bowl or dish shape such that when the diaphragm is installed into the valve, the two diaphragm membranes forces the diaphragm into the lower position.
Figure 3 is a drawing of diaphragm 328 in an example embodiment of the invention. Figure 3a is a top view of diaphragm 328. in an example embodiment of the invention.

Figure 3b is a sectional view AA from top view 3a, in an example embodiment of the invention. Diaphragm 328 comprises upper diaphragm membrane 308. lower diaphragm membrane 310, center section 312, upper rim 318 and lower rim 320. In one example embodiment, diaphragm 328 is generally circular in shape. In other example embodiments of the invention, diaphragm 328 may be ovai or rectangular in shape. Other shapes are also possible. Upper diaphragm membrane 308 is attached to lower diaphragm membrane 310 by center section 31 2 that holds the two diaphragm membranes in a spaced apart relationship, in one example embodiment of the invention, upper diaphragm membrane is generally parallel with lower diaphragm membrane 310. In another example embodiment of the invention, upper diaphragm membrane is not parallel with lower diaphragm membrane 310. In one example embodiment of the invention the upper and lower rims are generally circular in shape. In other example embodiments of the invention, the rims may be oval or rectangular in shape. The upper and lower rims (31 S and 320) are configured to fit into a gap between the top plate and the valve body and the bottom plate and the valve body. The rims help hoid diaphragm 328 in place in the valve and create a seal between diaphragm 328 and the valve. The upper and lower rims on the two diaphragm membranes are optional. Other methods may be used to hold the diaphragm membranes into the valve. For example, a groove or channel may be formed in the outer edge of tlie diaphragm membrane and a lip or bead may be formed on the top plate or on the valve bod\' that fits into the groove. Upper diaphragm membrane 308 is coupled to upper rim 318 along the inner diameter of upper rim 318. Lower diaphragm membrane 310 is coupled to lower rim 320 along the inner diameter of lower rim 320. Diaphragm 328 is fabricated in one piece. Upper diaphragm membrane 308 has thickness t. Upper diaphragm membrane 308 has a bowl or dish shape. The outer edge of upper diaphragm membrane 308 is fomied in essentially one plane shown as BB. The inner part of upper diaphragm membrane 308, where it joins with the central section 312. is formed in essentially one plane as shown by CC. Plane CC is offset, but generally parade! to plane BB. The offset between the inner and th*e outer areas of upper diaphragm membrane, 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. In one example embodiment of the invention, lower diaphragm membrane also has a dish or bowl shape that is aligned in the same direction as the dish or bowl shape of the upper diaphragm membrane, in other

example embodiments of the invention, lower diaphragm membrane may be flat or ha-ve a bowl shape that is not aligned with the upper diaphragm membrane.
Figure 4 is a flow chart for assemblingg a diaphragm valve in an example embodiment of the invention- At step 402 the upper diaphragm membrane is compressed. At step 404 the compressed upper membrane is inserted through the central opening in the valve body. At step 406 the compressed upper diaphragm membrane is released such that the valve body is captured between the upper diaphragm membrane and the lower diaphragm membrane with the center section of the diaphragm located in the central opening in the valve body. Either the upper diaphragm membrane or the lower diaphragm membrane can be compressed and insened through the central opening in the valve body. At optional step 408. an upper and lower rim is seated into an upper and lower groove respectively, where the upper and lower grooves are formed into a top and bottom surface of the valve body. At step 410 atop plate is attached to the top surface of the valve body holding the upper diaphragm membrane between the top plate and the valve body. At step 4) 2 a bottom plate is attached to the bottom surface of the valve body holding the lower diaphragm membrane between the bottom piate and the valve body.

CLAIMS:
(1) Cathode 1 for aluminium electraiysis ce«5 comprising a csrtior or graphite cathode block 4 with a collector bar slot 3 receiving one or two steel-made current collector bars 2, cfiaracterized in that the depth of slot 3 Is higher at the center C than at both lateral edges of cathode block 4.
{2) Cathode 1 according to claim 1, characlerized ir that the collector bar slot 3 has
a triangular, semi-circular or semi-eliipsojdal shape-
(3) Cathode 1 according to Glaims 1 or 2, characterized in that the collector bar slat 3 comprises one or more steps.
(4) Cathode 1 according to one of the claims 1 to 3, characterized in that the collector bar slot 3 has an initial planar top face at both lateral block adges stretching over 10 to 1000 mm from each edge.
(5) Cathode 1 according to to ons of the claims 1 to 4, characterized in that the thickness of the one or two collector bars 2 is higher at higher at the center C than at tfoih lateral edges of cathode block 4.
{6} Cathode 1 according to claim 5, characlerized in that the thickness of the one or two collector bars 2 is increased exclusively at the face facing the slot 3 top face.
(7) Cathode 1 according to dalms 5 or 6, characterized in that the one or two collector bars 2 have a triangular, semi-circular QT semi-ellipsoidal sdape.
(8) Cathode 1 according to one of the claims 5 to 7, characterized in that the the thickness of the one or twa collector bars 2 comprises Increases by one or more
steps.
(9) Cathode 1 according to one of the claims 5 to S, characterized in that the one or
two collector bars 2 have at least one steel plate 9 attached to it
(10) Cathode 1 according to claim 9, characterized In that resilient graphite foil is

placec between the at least one steel plala 9 and steel collector bar 2 as well as between each subsequently attached steal piale 9,
{11} Cathode 1 according to ona of the claims 1 to 10 having more (han one collector bar slot 3.
(12) Method of manufacturing cathodes 1 for aluminium electrolysis cells,
characterized by the steps
- manufacturing a carbon or graphite cathode block 4 with standard External
dimensions,
■ machining at feasf one collector bar slot 3 with iacreasing depfli towards the cathode block center C, fitting at least one steel collector bar 2 Info each of the at least one slots 3,
(13) Method of manufacturing cathodes 1 for aluminium electrolysis cells,
characterized by the steps
- manufacturing a carbon or graphite cathode bioci dimensions.
machining at least one collBctor bar slot 3 with increasing depth towards
the cathode blocic center C,
fitting at least one steel collector bar 2 with Increasing thickness at the face
facing the col lector bar slot 3 top face towards its center C into each of the
atieastoneslotsS.
(14} Aluminium electrolysis celis containing cathodes 1 according to one of the claims 1 to 11.

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Patent Number

278888

Indian Patent Application Number

5477/CHENP/2008

PG Journal Number

01/2017

Publication Date

06-Jan-2017

Grant Date

03-Jan-2017

Date of Filing

13-Oct-2008

Name of Patentee

SGL Carbon SE

Applicant Address

Sohnleinstr. 8, 65201 Wiesbaden, Deutschland; Nationality : Germany

Inventors:

#	Inventor's Name	Inventor's Address
1	HILTMANN, FRANK,	SITTIGSTRASSE 13, 65830 KRIFTEL
2	BEGHEIN, PHILIPPE,	249 LA COMBE, 74190 PASSY,

PCT International Classification Number

C25C3/16

PCT International Application Number

PCT/EP06/12334

PCT International Filing date

2006-12-20

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	06007808.6	2006-04-13	EUROPEAN UNION