| 摘要 |
<p>A manually actuated dispensing pump has a pump housing (10) for mounting with a closure cap (11) at an upper end of a container for fluent product, the housing having a pump cylinder (12) open at its outer end to atmosphere and providing at its inner end area a pump chamber (13) for a manually reciprocable piston (14) having a resilient piston seal (21). The cylinder has in its lower area at least one vent port (17) positioned outwardly of the pump chamber, the piston having a vent seal (19) for closing communication between the open end of said cylinder and the vent port. The piston forms a sub-assembly with the housing upon insertion into said cylinder (12) through the open outer end thereof, and one or more ramps (29) or tapered ribs are provided adjacent the vent port (17) for spacing the piston seal (21) from an inner edge of the vent port permitting the piston seal to by-pass the vent port to avoid any damage of the piston seal upon assembly into the cylinder.</p> |
