Patent ID: 6220565
Filing Date: 2001-04-24
Classification: F16K

Abstract:
A safety valve assembly having a main valve (5) and a pilot valve (6) arranged between a pressure port (P) and a discharge port (R), the main valve (5) being adjusted to open when the pilot valve (6) opens, the safety valve assembly comprising:the main valve (5) comprising a first valve seat (11) provided between the pressure port (P) and the discharge port (R), a first closure member (14) which makes an opening and closing movement to the first valve seat (11) and an urging means (21) which urges the first closure member (14) to the first valve seat (11);a restricting passage (16) having an inlet and an outlet and being provided within the first closure member (14), the inlet communicating with an interior area of the first valve seat (11);an actuation chamber (17) for valve closing which communicates with the outlet of the restricting passage (16) and pressurizes the first closure member (14) in a closing direction;a fitting wall (23) having a fitting portion (24) with which the first closure member (14) fits by a predetermined length at a final time of its closing movement, the fitting wall (23) being arranged between the pressure port (P) and the discharge port (R) in a radially outer space of the first valve seat (11);a valve-opening holding chamber (25) formed from an inner space defined by the fitting portion (24);the pilot valve (6) comprising a second valve seat (31) provided between the actuation chamber (17) for valve closing and the discharge port (R), a second closure member (34) which makes an opening and closing movement to the second valve seat (31), and a pushing means (37) which brings the second closure member (34) into closing contact with the second valve seat (31); anda sealing sectional area (S) of the second valve seat (31), a sealing sectional area (T) of the first valve seat (11), a pressurizing sectional area (U) of the actuation chamber (17) and a pressurizing sectional area (V) of the valve-opening holding chamber (25) set to values enlarging one after the other in the mentioned order.