Patent ID: 6805156
Filing Date: 2004-10-19
Classification: G05D,Y10T

Abstract:
A constant flow valve comprised ofa valve body (10), a valve action chamber (20) and connecting channel (50) formed at said valve body, a valve mechanism (30) attached in said valve action chamber, and a restrictor (60) provided in said connecting channel, wherein said valve action chamber (20) is formed with a primary side fluid inlet port (11), a valve seat (15), an outlet port (12) to said connecting channel, an inlet port (13) from said connecting channel, and a secondary side fluid outlet port (14); said valve mechanism (30) is provided with a first diaphragm (41), a second diaphragm (42), and a third diaphragm (43) moving together with a valve element (31), said first diaphragm (41) has an effective pressure receiving area (S1b) substantially equal to a valve seat upstream side pressure receiving face (Va) of said valve element, is attached inside said valve action chamber, and has one surface (41a) defining part of an air pressure chamber (21) and another surface (41b) defining part of a first chamber (22) having said primary side fluid inlet port and valve seat upstream part; said second diaphragm (42) is attached in said valve action chamber, and has one surface (42a) defining a second chamber (23) having the outlet port to said connecting channel and valve seat downstream part and another surface (42b) defining a third chamber (24) having the inlet port from said connecting channel and the secondary side fluid outlet port; said third diaphragm (43) has an effective pressure receiving area (S3a) substantially equal to a valve seat downstream side pressure receiving face (Vb) of said valve element, is attached inside said valve action chamber, and has one surface (43a) defining part of said third chamber and another surface (43b) defining part of a pressurizing chamber (25); said valve element advances and retracts with respect to said valve seat together with movement of said valve mechanism; and said pressurizing chamber is provided with a pressurizing means (72) for pressing said valve mechanism by a predetermined pressure.