| 摘要 |
<p>A discharge valve is provided for a finger-operable pump (20, 20F) with an actuating plunger (80, 71F and 69F). The actuating plunger defines a discharge passage (86, 102, 104 or 86F, 102F and 104F) in communication with the ambient atmosphere. The discharge valve includes a valve seat (120, 120F) defined by the plunger in the discharge passage. A valve member (110, 110F) is disposed in the discharge passage and is movable: (a) upstream to a closed position against the valve seat wherein the valve member defines a first area subjected to the chamber pressure and: (b) downstream to an open position away from the valve seat wherein the valve member defines a second area subjected to the chamber pressure such that the net pressure force imposed on the valve member by the chamber pressure is greater when the valve member is opened than when the valve member is closed. A spring (118, 118F) biases the valve member toward the valve seat.</p> |
