Slide ring sealing assembly with bellows and fluid pressure control of sealing pressure

A slide ring seal assembly sealing a gap between a rotatable shaft and a fixed wall and separating a pressure fluid space on one side of the fixed wall from a space on the other side of the wall, said assembly comprising:

• a non-rotatable, axially slidable seal ring surrounding said shaft;
• a bellows member surrounding said shaft and having an end fixed to said non-rotatable seal ring and an opposite end fixed to said fixed wall;
• a rotatable seal ring surrounding said shaft and fixed thereto, said rotatable and non-rotatable seal rings having sealing surfaces which are slidably engaged with each other and which are axially pressed against one another;
• means forming a control space around said bellows and sealing said space from said pressure fluid space and from said space on said other side of said wall;
• and control means for selectively increasing and decreasing the axial force which presses said sealing surfaces together, said means including fluid pressure supply means, different from the fluid in said pressure fluid space, for selectively increasing and decreasing the pressure in said control space to thereby selectively extend and contract said bellows whereby said non-rotatable sealing ring is moved axially relative to said shaft.