ADJUSTABLE AXIAL-FLOW PISTON MACHINE Russian patent published in 2007 - IPC F04B1/26 

FIELD: adjustable hydraulic machines including variable-displacement axial-flow piston machines.

SUBSTANCE: proposed machine has differential-control piston installed in housing and kinematically coupled with rocking-assembly distributor, and control valve incorporating slide valve and relevant control element. Adjusting-mechanism housing has cover. Differential piston has two sections, large-diameter and small-diameter ones. Rod cavity is formed between small-diameter butt-end surface of control piston and housing. Piston cavity is formed between large-diameter butt-end surface and housing. Working-pressure line of machine communicates with rod cavity. Slide valve is disposed in adjusting-mechanism housing cover mounted on piston cavity end. Cover has channel running to piston cavity. The latter communicates through channels made in cover and slide valve with working-pressure line and with drain. Working line and drain communicate with piston cavity through respective channels in slide valve provided on opposite end surfaces of slide valve isolated from one another. When machine is idle, piston cavity is held at working-medium pressure which is lower than control piston motion pressure. Slide-valve control element is mounted for acting on this slide valve to ensure its displacement relative to adjusting-mechanism housing cover. When machine is running, communication between piston cavity and high-pressure line is maintained by the end of adjustment cycle which compensates for working medium leakage from piston cavity.

EFFECT: enhanced adjustment characteristics and operating reliability due to enhanced control sensitivity.

1 cl, 4 dwg