Pressure actuated shut-off valve with membrane
An ON/OFF valve ( 1,1′,1″ ) that has an outer body ( 3 ) defining a fluid flow cavity ( 2 ) divided by an intermediate surface ( 8, 21 ) into a first and a second chamber ( 2 a, 2 b ) communicating with each other via an opening section ( 6, 28 ) in the intermediate surface ( 8, 21 ). A flexible shutter ( 7 ) has on the side facing the first chamber ( 2 a ), a membrane portion ( 17 ) that cooperates elastically, by virtue of a fluid pressure, with the intermediate surface ( 8, 21 ) and with the opening section ( 6, 28 ) to separate the first and second chamber ( 2 a, 2 b ) hermetica1ly. Fluid leakage generating members ( 20, 27 ) are located between the membrane portion ( 17 ) of the shutter ( 7 ) and the opening section ( 6, 28 ), and are active when the pressure in the first chamber ( 2 a ) exceeds the pressure in the second chamber ( 2 b ) by an amount equal to or less than a threshold value (P) other than zero.
1. An ON/OFF valve ( 1 , 1 ′, 1 ″) comprising:
an outer body ( 3 ) defining a fluid flow cavity ( 2 ) divided by an intermediate surface ( 8 , 21 ) into a first and a second chamber ( 2 a , 2 b ) communicating with each other via an opening section ( 6 , 28 ) in the intermediate surface ( 8 , 21 ); and
a flexible shutter ( 7 ) having, on the side facing said first chamber ( 2 a ), a membrane portion ( 17 ) cooperating elastically, by virtue of a fluid pressure, with said intermediate surface ( 8 , 21 ) and with said opening section ( 6 , 28 ) to separate said first and said second chamber ( 2 a , 2 b ) hermetically;
characterized by comprising fluid leakage generating means ( 20 , 27 ) located between said membrane portion ( 17 ) of said shutter ( 7 ) and said opening section ( 6 , 28 ), and which are active when the pressure in said first chamber ( 2 a ) exceeds the pressure in said second chamber ( 2 b ) by an amount equal to or less than a threshold value (P) other than zero, said fluid leakage generating means including a number of grooves ( 20 ) formed in said intermediate surface ( 8 ) that are equally spaced about a central axis (A) of said intermediate surface ( 8 ) and extend radially with respect to said axis (A), said grooves ( 20 ) communicating with said opening section ( 6 ), and said threshold value (P) being a function of the geometry of said grooves ( 20 ).
2. A valve as claimed in claim 1 , characterized in that said shutter ( 7 ) comprises a stem ( 15 ) extending inside said second chamber ( 2 b ); and in that said membrane portion ( 17 ) projects radially from one end of said stem ( 15 ).
3. A valve as claimed in claim 1 , characterized in that said intermediate surface ( 8 , 21 ) is annular, and centrally defines said opening section ( 6 , 28 ).
4. A valve as claimed in claim 1 , characterized in that said groove ( 20 ) extends from a radially-outer peripheral edge of said opening section ( 6 ), and projects radially with respect to said membrane portion ( 17 ).
5. A valve as claimed in claim 1 , characterized in that said groove ( 20 ) has an open U-shaped cross section.
6. A valve as claimed in claim 1 , characterized in that said opening section ( 6 ) comprises two substantially half-moon-shaped openings ( 10 , 11 ) defining, on opposite sides, a seating portion ( 12 ) for said stem ( 15 ) of said shutter ( 7 ).
7. A valve as claimed in claim 1 , characterized by comprising a disk-shaped base member ( 5 ) housed hermetically in said cavity ( 2 ), and which defines said intermediate surface ( 8 ) on the side facing said first chamber ( 2 a ); said stern ( 15 ) being fitted coaxially through said base member ( 5 ).
8. A valve as claimed in claim 1 , characterized in that said membrane portion ( 17 ) of said shutter ( 7 ) is circular-dome-shaped and convex on the side facing said first chamber ( 2 a ).