| 摘要 |
A double-staged, rotary pump and a fluid flow control device is disclosed. An inner rotary member is fixed to a rotatable drive shaft. The inner rotary member has n circumferentially spaced radially projecting teeth. An intermediate rotary member having n+1 internal teeth encircles the inner rotary member and is mounted for rotation about an axis eccentrically disposed from the drive shaft axis. The intermediate member has n+1 circumferentially spaced radially projecting teeth. An outer rotary member having n+2 circumferentially spaced internal teeth encircles the intermediate member and is mounted for rotation about an axis coincident with the drive shaft axis. The inner rotary member drivingly engages the intermediate rotary member which in turn drivingly engages the outer rotary member, all members rotating in the same direction. The external teeth of the inner rotary member and the internal teeth of the intermediate rotary member define a first set of successive expanding pumping chambers and a first set of successive contracting pumping chambers. The external teeth of the intermediate rotary member and the internal teeth of the outer rotary member define a second set of successive expanding pumping chambers and a second set of successive contracting pumping chambers. A valve control means is provided to connect the first pump stage and the second pump stage in differing modes to effectuate series communication, and to effect parallel communication. The valve control means also provides connection with one of the pump stages while connecting the other pump stage to itself.
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