Electric valves

An electric valve comprising a casing which has an inlet and an outlet connection, a seat for a membrane, a magnetically actuated valve shutter, a flexible, impervious membrane, clamped at its periphery, and an insert tightly held in the midportion of said membrane and having a hole therethrough, said membrane being in contact with said seat so as to define with the casing and the insert a control chamber which communicates with the outlet connection by said hole provided in said insert, which hole is normally closed by said valve shutter, said control member also communicating with the inlet connection by a restricted passage, and magnetic means for actuating said valve shutter so that it disengages from the hole, and further comprising the improvement which consists in that:

• said casing is made of a first portion and a second portion both made of the same thermoplastic material, said first portion being shaped as a valve body and said second portion being shaped as a cap for said valve body shape and defining said control chamber with said membrane and said insert thereof and also supporting said valve shutter and said magnetic actuating means;
• said control chamber, outlet connection, membrane, insert and actuator have an axis common to surface-of-revolution shaping of each of them;
• said membrane has an annularly cylindrical peripheral rim having at least one cylindrical surface substantially coaxial with said axis and said rim is restrained in a radial direction by a cylindrical surface of one of said casing portions likewise coaxial with said axis;
• and
• said first and second portions respectively have opposite stepped portions where they meet which are formed by cylindrical riser surfaces coaxial with said axis offset radially by surfaces perpendicular to said axis, two opposed pairs of said step riser surfaces being overlapped and fused by ultrasonic thermomechanical bonding under axial forcing together of said portions by reason of the diameter of the external riser surface of the casing portion that fits inside the other casing portion at their joint being slightly greater than the internal diameter of the internal riser surface of said outer casing portion at the joint, said two pairs of fused step riser surfaces being separated by an intermediate pair of said step riser surfaces of said respective casing portions which are separated from each other by the width of a pair of said radially offsetting surfaces likewise separated from each other, so that an annular cavity is formed thereby which is at least partially filled with material squeezed out from at least one of the fused overlaps of said adjacent opposed pairs of riser surfaces of said respective casing portions,
• whereby axially and radially offset tandem sealed annular bonds are provided joining said first and second casing portions and seal said casing peripherally independently of the manner in which said membrane is held therein.