Suction button assembly for endoscope

A suction button assembly for an endoscope including an operation unit, a section of an elongated tube for entry in a body cavity, and a suction channel and a discharge conduit disposed with said operation unit, wherein a distal opening is formed in a distal end of said elongated tube, said suction channel is disposed to extend to said distal opening, said discharge conduit is connected to a negative pressure source, said suction button assembly comprising:

• a cylinder housing, disposed on said operation unit, and including a cylinder passage, a valve engaging surface and a flow opening, said cylinder passage being formed through said cylinder housing, said valve engaging surface being disposed in said cylinder passage, said flow opening formed in a wall of said cylinder passage, said cylinder passage having first and second cylinder openings, said first cylinder opening being connected to said suction channel, said valve engaging surface being tapered with an inner diameter decreasing from said first cylinder opening toward said second cylinder opening, said discharge conduit extending from said flow opening;
• a plunger, contained in said cylinder passage in a slidable manner, and including a stem end, a valve head and a flow channel, said stem end protruding from said second cylinder opening, said valve head being movable to and from said valve engaging surface for contact, said flow channel being opposed to said flow opening, wherein said plunger is in a closed position when said stem end is free without being depressed, and is in an open position when said stem end is depressed, and said valve head, when said plunger is in said closed position, contacts said valve engaging surface for interruption between said suction channel and said discharge conduit, and when said plunger is in said open position, leaves from said valve engaging surface for communication between said suction channel and said discharge conduit in cooperation with said flow channel aligned with said flow opening.