Patent ID: 7004451

Claim:
A ball cock for controlling media flow comprising: (a) a housing having at least two housing parts, each of said housing parts having a respective flow-through channel for forming a respective flow-through path for a medium; (b) a ball-shaped shut-off element having a passage bore for forming a flow path for selectively connecting said flow-through paths, said shut-off element being disposed within only two housing parts of said housing between ring-shaped seals and being movable via a switching shaft between an open position where said flow path is opened and a closed position where said flow path is closed; wherein at least one of said seals is mounted in one of said housing parts with limited axial mobility and has a sealing surface for pressing against said shut-off element; wherein said at least one seal is coupled with a device for moving said at least one seal between an axial contact pressure position where said sealing surface is pressed against said shut-off element and a stress-relief position where said sealing surface either rests against said shut-off element at a reduced surface pressure relative to said contact pressure position or is lifted off said shut-off element; and wherein said sealing surface is pressed against said shut-off element in the contact pressure position, irrespective of any spring forces that are applied to said at least one seal; and (c) a switching channel connected to said at least one seal and arranged in sealed manner relative to an associated one of said flow-through channels, to selectively receive pressure of a separate working medium for causing said at least one seal to move between the contact pressure position and the stress-relief position; wherein said at least one seal has working surfaces that face toward the shut-off element and contact surfaces that face away from said shut-off element, said working surfaces and said contact surfaces receiving the medium when the medium flows through the flow-through channel of an associated one of said flow-through channels for said at least one seal and when said at least one seal is pressed against the shut-off element with its sealing surface, said working surfaces having a first projection surface projected in a first projection plane that runs perpendicular to an axial displacement direction of the seal and said contact surfaces having a second projection surface projected in a second projection plane arranged parallel to the first projection plane, said first projection surface being at least as great as said second projection surface.