All Products for US Patent 5271722 - Automotive control system for hydrostatic pumps

Inventor(s): Hansell; Jeffrey C. (Ames, IA)

Owner: Sauer Inc. (Ames, IA)

Filing Date: January 11, 1993

Issue Date: December 21, 1993

Abstract: An automotive control system for hydrostatic pumps includes a hydraulic circuit with an automotive orifice located upstream of the main hydrostatic loop with replenishing check valves and downstream of the fill pump. The location of the automotive orifice upstream of the check valves isolates system leakage from affecting flow to the automotive orifice. A hydrostatic unit displacement control valve has a drain side connected to the hydraulic circuit downstream of the fill pump and in parallel with the automotive orifice, and has a supply side connected downstream of the automotive control orifice. The input logic of the control valve is reversed to compensate for the greater pressure available to the drain side of the control valve as compared to the supply side. Reversing the input logic of the control valve provides servo control pressures without the need to isolate the control supply from the hydrostatic loop supply.