Piston-diaphragm assembly for a valve and a manufacturing method

A piston-diaphragm assembly for a valve, the assembly comprising:

• a piston that comprises:
• a stem, which extends parallel to a distal direction, the stem being intended to be received in a central conduit of a body of the valve, in a sliding manner relative to the body parallel to the distal direction, the stem comprising a piston groove surrounding the stem and being radially outwardly open, the piston groove comprising a groove proximal rim and a groove distal rim between which the piston groove is delimited, the groove distal rim being offset from the groove proximal rim in the distal direction;
• and
• a needle, which is fastened to a stem distal end, belonging to the stem, and which is configured to abut against a shut-off seat along the distal direction to shut off a pressurized fluid conduit;
• and
• a diaphragm that comprises:
• a peripheral annular ring for fastening the diaphragm to the body of the valve, the peripheral annular ring surrounding the piston;
• an internal annular ring, which surrounds the piston and is received in the piston groove to thereby attach the diaphragm to the piston;
• and
• an annular membrane, which connects the peripheral annular ring to the internal annular ring;
• wherein the needle comprises:
• a crown which surrounds the stem and externally covers the internal annular ring;
• and
• a crown rim which ends the crown in a direction opposite to the distal direction, the crown rim being arranged at the height of the groove proximal rim, the diaphragm being radially interposed between the groove proximal rim and the crown rim and being in contact with the crown rim.