| 摘要 |
A suction pump, e.g. an engine oil exchange pump, comprises reservoir 11, cap 12, inlet hose 16, an evacuator e.g. piston or venturi pump and an automatic pressure-relieving apparatus. The apparatus comprises a through cap passage 15 with exterior 151 and reservoir 152 openings and a peripheral vent hole 154. Reservoir air flows through the evacuation device via the reservoir opening, the vent hole and a cap passage 121. A first rod 21 in the passage has an upper seal 211 releasably sealing the exterior opening and a second rod 22 coupled to the first passes through the reservoir opening into the reservoir and carries a spring 221b mounted seal 221 releasably sealing the reservoir opening. A control device, e.g. a float, acts, e.g. through a rack and pinion, on the second rod so that rising reservoir contents lift the rods to open and close the exterior and reservoir openings respectively. Prevents contents entering the cap, unloads the evacuator and the sprung seal allows vacuum relief. |
