Electro-hydraulic valve control system for internal combustion engine valves

US4466390A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Rudolf Babitzka · Kirchberg, DE
• Wilhelm Polach · Asperg, DE
• Walter Schlagmuller · Schwieberdingen, DE

Key dates

• Filing date: Sep 9, 1982
• Grant date: Aug 21, 1984
• Expiry date: Sep 9, 2002

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F01L9/14
• WIPO field: Engines, pumps, turbines
• WIPO sector: Mechanical engineering

Abstract

Electric control of a hydraulic valve control system is obtained by providing hydraulic fluid to form a hydraulic plug between a cam follower in engagement with the camshaft of the engine and a valve stem (11), the hydraulic plug or hydraulic fluid being retained in a chamber which, under control of an electrically operated valve (20, 25; 38), can establish communication to a drain line (19, 47). For rapid movement, the valve can be clamped in closed position by a piezoelectric column (FIG. 1: 28) to prevent drainage, and, upon clamping release of the column, permit drainage, and hence release of the "hydraulic plug", and thus provide for closing action of the valve under operation of a valve spring (13) to thereby shorten the open-time of the valve (FIG. 2, compare curves 31, 32, 33). A spool slider valve can also be used, the position of which is controlled by a pilot valve (FIG. 3: 40, 57, 64) in which a piezoelectric element moves a piston (57) which establishes pressure differential on a slider spool (42) which, respectively, connects the hydraulic plug to a drain (47) or prevents drainage, thus transferring movement of a cam (3) from the camshaft to the cam follower (4) and h…