Patent ID: 7011295

Claim:
A vacuum regulating valve comprising: a valve casing having a cylindrical valve chamber extending along an axis, and provided with a first port having an axis parallel to the axis of the valve chamber and a first open end opening into the valve chamber, and a second port having an axis perpendicular to the axis of the valve chamber and a second open end opening into the valve chamber; a valve seat defining the first open end; a disk-shaped valve element capable of being seated on the valve seat to give a tight closure on the valve seat; a valve stem extending from a back part of the valve element coaxially with the valve chamber; a valve operating unit for operating the valve element through the valve stem for opening and closing operations; an extendable bellows disposed in the valve chamber so as to surround the valve stem in an airtight fashion; and a cylindrical baffle member disposed behind the valve element so as to surround the bellows and capable of moving together with the valve element; wherein the baffle member has a base part attached to the valve element and an open free end, and is formed in an axial length such that the baffle member is able to cover the second open end entirely when the valve element is seated on the valve seat; outside diameter of the baffle member is determined such that an outside space of the smallest possible thickness is defined between an outer circumference of the baffle member and an inner circumference of a side wall of the valve casing, the thickness of the outside space is great enough to keep the baffle member spaced from the inner circumference of the side wall of the valve casing and is small enough to prevent a fluid from flowing through the outside space into an inside space formed between the baffle member and an imaginary cylinder circumscribed about the bellows; and the inside space has a thickness greater than that of the outside space.