Importance

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Abstract

A bellows-type pressure responsive valve comprising bellows 66 of a closed structure as a pressure sensing element adapted to vary an opening amount of the valve by transmitting expansions and contractions of the bellows 66 to a valve body 61 by means of a valve rod 65 which is supported on a valve housing 51 so as to move in a valve lifting direction, characterized in that the bellows 66 and the valve rod 65 are spherically connected by means of a spherical coupling structure which is incorporated at a connecting portion of the bellows 66 and the valve rod 65 and composed of a ball 77 which is rotatably disposed coaxially with the valve rod 65, and a spherical recess 78 which is formed at a closed end face 67a of a bellows body 67 of the bellows 66 at a central position thereof. With this structure, centripetal motions of the bellows and the valve rod are automatically effected by means of the spherical coupling between the bellows and the valve rod. Therefore, even though the bellows is weaving or inclined, the unsymmetrical abutment between the bellows and the valve rod can be avoided. Further, forces based on the weaving of the bellows in directions intersecting the valve lifting direction, that is, other directions than the valve lifting direction will be absorbed by the spherical movement of the first spherical coupling structure. Thus, the forces in the other directions than the valve lifting direction will not be transmitted to the valve rod, the hysteresis in the valve motions will be minimized, and a high controlling accuracy can be obtained.

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First Claim