Regulator

A regulator, comprising:

• a main body portion including a passage formed through the main body portion, one opening end of the passage serving as an introduction port for introducing a fluid and another opening end of the passage serving as an extraction port for extracting a fluid;
• a valve seat including a valve-seated seat on an inner side in the introduction port of the passage and a valve-seated seat holding member having a through-hole in an axial direction of the passage;
• a pressure regulating chamber formed on a downstream side of the valve-seated seat in the passage;
• a piston pressure regulating valve including a pressure regulating valve element having an end surface that is contactable with the valve-seated seat, the piston pressure regulating valve disposed between the pressure regulating chamber of the passage and the introduction port, the piston pressure regulating valve including a communication passage having a cylindrical shape with both ends opened;
• the piston pressure regulating valve further including a piston portion formed to surround an outer periphery of a fitting portion of the pressure regulating valve element on an extraction port side of the passage, the piston portion slidable in an axial direction of the passage and biased in a direction of the extraction port of the passage via a pressure regulating spring having a predetermined load disposed in an atmosphere chamber provided coaxially in parallel with the pressure regulating chamber around the piston portion;
• wherein, during operation, the fluid introduced through the introduction port is introduced into the pressure regulating chamber via the through-hole formed in the valve-seated seat holding member and passes through the pressure regulating valve element in which the communication passage is formed, a load due to a pressure of a fluid acting on the piston portion joined to the pressure regulating valve element and a load due to the pressure regulating spring acting on the piston portion on a side opposite to the pressure regulating chamber are balanced such that an opening area of the valve-seated seat and the pressure regulating valve element is changed to control a fluid pressure in the pressure regulating chamber, and a fluid regulated to a desired pressure is taken out from the extraction port;
• wherein the pressure regulating valve element and the piston portion are separately formed;
• wherein the pressure regulating valve element is insertable into the passage through the introduction port and the piston portion is insertable into the passage through the extraction port, and the pressure regulating valve element and the piston portion are fitted to each other at an axial position and then fixed via at least one of press-fitting and welding at a fixing portion;
• wherein the pressure regulating valve element includes a step protruding from the fitting portion at an upstream position disposed spaced apart from the fixing portion at an outer peripheral portion of the pressure regulating valve element;
• and
• wherein, in a case where fixation between the pressure regulating valve element and the piston portion is released, when the pressure regulating chamber reaches a predetermined pressure, the piston portion presses the step of the pressure regulating valve element against a biasing force of the pressure regulating spring and closes the pressure regulating valve element.