Valve seat for an insufflation cannula assembly

Claim 1

A flapper valve for an insufflation cannula assembly, the cannula assembly including a cannula defining a cannula passage and a housing mounted on one end of the cannula and having an opening formed therein, the flapper valve being mounted in the housing of the assembly, the flapper valve comprising: a valve seat within the housing opening, said valve seat being formed of a resilient flexible material and having an opening formed therein, said valve seat opening being bounded by a lip extending at least generally radially inwardly of said valve seat, at least a portion of said lip being of reduced thickness, said reduced thickness portion thereby being of greater flexibility than adjacent portions of said valve seat, said valve seat opening being in communication with the cannula passage and being adapted to allow a surgical instrument to pass therethrough and into the cannula passage; a valve plate pivotally mounted in said housing, said valve plate having front and back faces, said front face of said valve plate being dimensioned and adapted to engage said resilient flexible lip of said valve seat, said valve plate including means for obstructing said opening in said valve seat by engagement with said lip of said valve seat in a manner to cause said lip to become resiliently flexed to thereby affect a substantially gas tight seal; and biasing means for biasing said valve plate into engagement with said lip of said valve seat.