Control valve for a variable displacement pump

US4699571A · kind A · utility

Assignee

• Mannesmann Rexroth AG · DE

Inventor

• Reiner Bartholomaus · Brück, DE

Key dates

• Filing date: Sep 30, 1985
• Grant date: Oct 13, 1987
• Expiry date: Sep 30, 2005

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F04B2205/15
• WIPO field: Engines, pumps, turbines
• WIPO sector: Mechanical engineering

Abstract

In the pressure regulation of a variable displacement pump very high pressures can build up in the pump delivery line if at the consumer no discharge of the fluid takes place, for example the piston of a servo motor moves against a stop. A pressure regulation of the pump is then only possible via the inner losses of the pump. Consequently, although the pressure can be built up rapidly it can only be reduced very slowly. According to the invention the pressure reduction is via a bypass which is controlled by the control valve of the variable displacement pump and which connects the pressure side of the pump to a tank discharge when the control valve is driven in the sense of a reduction of the pump pressure. According to the invention a very rapid pressure reduction is obtained so that the variable displacement pump can again be pressure controlled.