PRESSURE CONTROL METHOD IN PRESSURE PROPORTIONAL CONTROL VALVE AND PRESSURE PROPORTIONAL CONTROL VALVE

摘要

PROBLEM TO BE SOLVED: To quickly and surely control pressure supplied to a load even when it is controlled to pressure approximate to external pressure. ;SOLUTION: The exhaust port of an exhaust solenoid valve of a pressure proportional control valve 1 is communicated with a negative pressure generating part 2. When a solenoid valve 27 is actuated, the negative pressure generating part 2 introduces supply pressure PI to generate the negative pressure in a negative pressure chamber where the exhaust port is communicated. A control section 24 is equipped with a comparator 44 which outputs a driving signal VD2 for actuating the solenoid valve 27 when an actual pressure signal VO is smaller than preset reference volt VCI. When target pressure is set up to pressure approximate to the atmospheric pressure, and pilot pressure Pp is thereby lowered, and actual pressure PO is therefore controlled to pressure approximate to the atmospheric pressure, a pilot chamber is communicated with a negative pressure source.;COPYRIGHT: (C)1997,JPO