Patent ID: 8443830
Filing Date: 2013-05-21
Classification: F16K,Y10T

Abstract:
1. A heater built-in valve comprising a valve box provided with a fluid passage, a casing provided above the valve box, a valve rod that moves up and down a valve element opening and closing the fluid passage, a piston that is arranged movably upward and downward inside the casing and is fixed to the valve rod, piston driving means for moving up and down the piston, heating means for heating a vicinity of the valve element, and sealing means for sealing between the piston and the casing, the heater built-in valve, wherein the piston driving means has an upper compressed-air introducing chamber for moving the piston downward, and a lower compressed-air introducing chamber for moving the piston upward, and the sealing means has an upper bellows that seals the upper compressed-air introducing chamber, and a lower bellows that seals the lower compressed-air introducing chamber, the piston includes a large-diameter cylindrical part and a small-diameter cylindrical part that continues below the large-diameter cylindrical part, and a first upper bellows which upper end is placed above an upper end of the piston large-diameter cylindrical part, and which is arranged inside the piston large-diameter cylindrical part, and a second upper bellows which upper end is placed above the upper end of the piston large-diameter cylindrical part, and which is arranged outside the piston large-diameter cylindrical part, respectively, so that bellows receiving parts that support the upper end portions of the respective bellows are provided in an upper portion of the casing, by which the upper compressed-air introducing chamber is formed by an upper end surface of the piston large-diameter cylindrical part, the upper portion of the casing, the first upper bellows and the second upper bellows, while a lower bellows is arranged outside the piston small-diameter cylindrical part, and a bellows receiving part that supports a lower end surface of the lower bellows is provided in a circumferential wall of the casing, by which the lower compressed-air introducing chamber is formed by the circumferential wall of the casing, the second upper bellows, a lower end portion of the piston large-diameter cylindrical part and the lower bellows.