| 摘要 |
A helical gear pump 18 has a rotor 44 rotatably mounted about the axis, the drive shaft 22, and at least two stators 42.1, 42.2, 42.3 of resilient material mounted operatively in series around the rotor 44, at least one of the stators 42.2 having an outer wall which is unconstrained against radial inward movement along a portion of its length. Delivery pressure in a clearance space 48 around the outside of such unconstrained wall of the stator 42.2, compensates at least in part for the internal pressure exerted radially outwardly tending to expand the stator 42.2. Such an arrangement, makes it possible the provision of less initial interference between rotor 44 and stator 42.2 thereby resulting in the use of a lower starting torque and making it possible for such pumps when fitted in boreholes, to be hand driven or to be driven by a windmill. Such an arrangement also makes possible the effective pumping of hot liquids, by having initial interference between the rotor 44 and the stator 42.2 than would have been necessary with a conventional rotor. |
