| 摘要 |
<p>A dispenser pump has an arrangement for sucking material out of its discharge nozzle (74) after a dispensing stroke, to avoid clogging. The material is sucked through a suck-back passage provided by minor non-complementarity between a resilient outlet valve disc (45) and its valve seat (41). The ball (6) of the inlet valve is arranged to travel vertically in a tubular portion (161) of the inlet passage in which it is a blocking fit, between its valve seat (62) and an open cup portion (61) where fluid flows freely past it into the pump chamber. During recharging at the pump chamber the ball (6) is held in the open cup position (61). Once recharging stops the ball (6) falls gradually down the tubular position (160), drawing liquid back through the pump chamber until the inlet valve reseats.</p> |
