| 摘要 |
PCT No. PCT/ES96/00182 Sec. 371 Date Aug. 28, 1997 Sec. 102(e) Date Aug. 28, 1997 PCT Filed Sep. 20, 1996 PCT Pub. No. WO97/11007 PCT Pub. Date Mar. 22, 1997A pump for pumping through a variable plunger chamber having a pair of plungers disposed in a stepped cylinder with a slide valve includes two plungers of different diameters, united to each other. As they move within a stepped cylinder, the plungers form a chamber of variable volume according to the ratio of their height in respect of the step formed by the cylinder. The ports and clearance between the stem and the plunger chamber create intake, by means of the port housed in the plunger chamber on driving the stem in its upward stroke, and drive by means of the port drilled in the stem on forcing the stem in its downward stroke. Just three structural components are needed for operation of the pump.
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