ELECTRICALLY-DRIVEN PUMPING UNIT Russian patent published in 1997 - IPC

FIELD: hydraulic automation. SUBSTANCE: electrically-driven pumping unit has electric motor and variable-capacity axial-flow plunger pump with zero output pressure regulator and direct regulator of swivel cradle position which includes differential servopiston and spring unit with stops connected with opposite edges of cradle; one stop is linked with cradle and other stop is linked with adjusting member of spring unit initial force provided with at least two coaxial springs of different stiffness. Embracing spring rests on both above-mentioned stops and embraced spring arranged inside first one is supported by one stop on one side and by additional spring-loaded support on other side. Spring-loaded support is mounted in initial position relative to second stop at clearance which is lesser than stroke of stop during motion of cradle between extreme positions. EFFECT: enhanced reliability. 4 dwg