Abstract: A relief valve for gas includes: a housing having a valve port connecting with an inflow passage and an outflow passage, and a tapered valve seat formed in the inflow passage to surround the valve port; a valve body having a tapered valve head part and movable between a closed position where the valve head part is seated and fits in the valve seat to close the valve port, and a full stroke position farthest from the valve seat; and a biasing member that biases the valve body to the closed position. The valve body has a seal member that is provided to externally fit on a seal groove formed on an outer circumferential face of the valve head part over an entire circumferential periphery, and to be seated on the valve seat in the closed position to seal between the valve seat and the valve head part.

Abstract: A valve device includes: a main valve element dividing a valve element space of a housing into first and second pressure chambers; a sealing member configured to isolate the first and second pressure chambers from each other; a first pilot passage including one end communicating with a primary passage, the other end communicating with the second pressure chamber, and a first restrictor; a second pilot passage including a second restrictor and formed at the main valve element; a pilot valve element configured to open and close the second pilot passage; a drive mechanism configured to, when a current flows through the drive mechanism, drive the pilot valve element such that the pilot valve element opens the second pilot passage against biasing force of a biasing member; and a pin coupling the main valve element and the pilot valve element to each other.

Abstract: A valve device includes: a main valve element dividing a valve element space of a housing into first and second pressure chambers; a sealing member configured to isolate the first and second pressure chambers from each other; a first pilot passage including one end communicating with a primary passage, the other end communicating with the second pressure chamber, and a first restrictor; a second pilot passage including a second restrictor and formed at the main valve element; a pilot valve element configured to open and close the second pilot passage; a drive mechanism configured to, when a current flows through the drive mechanism, drive the pilot valve element such that the pilot valve element opens the second pilot passage against biasing force of a biasing member; and a pin coupling the main valve element and the pilot valve element to each other.

Abstract: A valve device includes main valve element and pilot valve element. The main valve element divides valve element space of housing into first pressure chamber and second pressure chamber. The pilot valve element is provided in the second pressure chamber. In one example, first pilot passage including first restrictor extends from primary passage to the second pressure chamber, and second pilot passage including second restrictor is formed at the main valve element. The main valve element and the pilot valve element are coupled to each other by pin, and gap is formed between the pin and one of the main valve element and the pilot valve element. The pilot valve element opens and closes the second pilot passage by biasing member and drive mechanism. The main valve element is driven so as to open the secondary passage by differential pressure between the first pressure chamber and the second pressure chamber.