Thermally controlled valve

A thermally-controlled valve comprising:

• a housing having an internal chamber which is communicative to an inlet and outlet;
• a valve seat element disposed in said housing having a valve seat for communicating the outlet to the inlet;
• a valve shaft slidably retained in said housing and extending through the opening defined by said valve seat and including a spherically-shaped, valve member communicative with said valve seat element;
• guide bushing elements diposed in said housing and having diametrical clearances for retaining at least a portion of said valve shaft on opposite sides of said valve seat;
• and
• a bimetallic element coupled to said shaft and in engagement with said valve seat element, for opening and closing said valve member, wherein the dimensions of the diametrical clearances between said guide bushing elements and said valve shaft portions are in a ratio with respect to each other which is proportional to the ratio of distances between the spherical center point of said valve member and the points at which said valve shaft radially engages said guide bushing elements when said valve member is in its closed position, whereby, upon engagement of said valve shaft with said guide bushing elements, said spherical center point of said valve member is aligned with the center axis of the opening defined by said valve seat.