| 摘要 |
Disclosed is an expanding gate valve that expands the gate assembly by engagement of symmetrical opposing inclined cam surfaces with corresponding symmetrical opposing wedges, where at least one of the wedges is driven by the stem that moves the gate assembly, and where the gate assembly is urged back toward the retracted position by at least one lateral-force-inducing member at least when the gate assembly is not in the closed position. Example compact and full body gate valve designs are disclosed. Lateral-force-inducing members may comprise one or more springs, such as a snap-ring, or may comprise cam followers running against surfaces defining the gate members' movement profile. A sealed sleeve is also disclosed that seals the interior of the valve body from pressure in the pipeline when the valve is open, while allowing the gate assembly to expand and retract laterally. |
