Pneumatic pressure regulator

A pneumatic regulator which regulates a discharge pressure value discharged from a main valve to a predetermined pressure value by increasing or decreasing a pilot pressure in response to a gas supplied to or discharged from a solenoid valve, wherein:

• said discharge pressure value is detected and a pressure difference between said discharge pressure value and said predetermined pressure value is supplied to a pulse-width modulation circuit, an integral control circuit and an absolute value circuit;
• an output of said integral control circuit is supplied to a pulse frequency modulation circuit;
• an output of said absolute value circuit is supplied to one input of a comparator;
• a reference signal is supplied to another input of said comparator as a given value;
• and
• said integral control circuit is reset by an output of said comparator or an output of said pulse frequency modulation circuit, and along with said resetting, an output of said pulse frequency modulation circuit and an output of said pulse-width modulation circuit are switched over by an output of said comparator and is supplied to said solenoid valve,
• in case said pressure difference is greater than said given value, a switching is performed based on an output of said comparator so as to make said pulse-width modulation circuit connected with said solenoid valve and said solenoid valve is driven by a pulse-width modulation signal,
• in case said pressure difference is smaller than said given value, based on an output of said comparator, said integral control circuit is reset and an integral action is started and a switching is performed so as to make said frequency modulation circuit connected with said solenoid valve, and when said integral value reaches a fixed threshold, a pulse frequency modulation signal having a fixed pulse-width is outputted from said pulse frequency modulation circuit and said solenoid is driven, and said integral control circuit is reset to start an integral action again.

A pneumatic regulator comprising:

• a main valve having a supply port, a discharge port and an exhaust port, wherein a stem which is displaced along an axial direction under a deflecting action of a diaphragm stretched inside is disposed at a central portion of said main valve and said main valve further includes a valve body which is opened or closed under a displacement action of said stem, and
• a bonnet integrally connected with an upper portion of said main valve and having a space portion,
• wherein in said space portion of said bonnet, a first solenoid valve and a second solenoid valve which control a pilot pressure supplied to a diaphragm chamber defined by said diaphragm, a pressure detection part which detects a discharge pressure value discharged from said discharge port, a control part which outputs a drive signal to said first solenoid valve and said second solenoid valve based on a discharge pressure signal transmitted from said pressure detection part, and a display part which displays at least a pressure value corresponding to a discharge pressure signal detected by said pressure detection part are disposed,
• further wherein with respect to said drive signal, in a case of a pressure difference between said discharge pressure value and a predetermined pressure value being greater than a given value, said first solenoid valve and said second solenoid valve are driven by a pulse width modulation signal, while in a case of said pressure difference being smaller than said given value, said first solenoid valve and said second solenoid valve are driven by a pulse frequency modulation signal.