Low-loss cyclically-operating pressure-responsive bypass valve for fixed displacement pump flow control

US4897996A · kind A · utility

Assignee

• MAN Nutzfahrzeuge AG · DE

Inventors

• Faust Hagin · Munich, DE
• Stefan Martini · Ulm, DE

Key dates

• Filing date: Jul 27, 1987
• Grant date: Feb 6, 1990
• Expiry date: Jul 27, 2007

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T137/2617
• WIPO field: Mechanical elements
• WIPO sector: Mechanical engineering

Abstract

In a system for varying the output flow from a constant rate feed pump with low losses by chopping the said output flow into one flow fraction supplied to the load as a power flow and into another flow fraction returned as a pressureless flow, the loads are aperiodically supplied with proportionated amounts of fluid by chopping, the respective amounts of fluid and the chop frequency being inherently controlled in way dependent on the instantaneous requirement of the load in the system. The system for performing the method has a housing with a number of pressure spaces arranged to be acted upon by different flows and with one or more pressureless spaces, a piston with a piston rod arranged in a piston space, a compression spring preferably arranged in a hole in said piston rod and adapted to act against the sum of the hydraulic forces acting on the piston and spool. The method is applicable to complex hydraulic systems and more especially to hydrostatic drives.