Fluid passage valve

A fluid passage valve comprising:

• a main body comprising a valve body which is disposed rotatably through a shaft, and a valve chamber in which the valve body is accommodated;
• a movable seat having a seating surface on which the valve body is seatable;
• and
• an elastic member for urging the movable seat toward a side opposite from the valve body about the movable seat, wherein:
• the valve body includes, as at least one portion thereof, a spherical surface portion formed as a spherical surface,
• the shaft is installed on the valve body such that an axis thereof is disposed at a position offset from a center of curvature of the spherical surface portion,
• the movable seat includes a communication hole therein, an axis of which lies substantially perpendicularly to the axis of the shaft,
• the spherical surface portion of the valve body abuts against the seating surface thereby producing a valve-closed condition by closing the communication hole, and
• a valve-open condition is produced by separating the valve body from the movable seat and opening the communication hole.