VALVE DEVICE

PURPOSE:To adjust a channel through low voltage, to reduce pressure loss, and to simplify a structure and reduce the size thereof by forming a valve device out of a valve body for switching and adjusting the opening of the channel following rotation, in the surface perpendicular to the channel, of a sealing material, and of a driving part of the valve body. CONSTITUTION:When a valve device is in an opened state, one side of a valve body 30 is abutted on a stopper pin 34a, while a communicating port 32 of the valve body 30 is concentrically opposed to a channel 28, which is in a completely opened state through the communicating port 32. The gas in a fluid passage 44 is flown from an upper stream side 44a through the channel 28 to a lower stream side 44b. The valve body 30 is sandwiched between each sealing material 29 vertically, and the leakage of the flowing gas is prevented thereby. When an abnormal detection signal is input to a driving circuit, a pulse signal of closing command is output, so as to drive a pulse motor, and the valve body 30 is rotated by a gear 40 through a gear part 35. By this rotational operation, the channel 28 is cut by the plate surface of the valve body 30, and is in a closed state. The pulse motor is then stopped, and it is thus ensured that the closed state is maintained.