The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 21, 1984
Filed:
Sep. 09, 1982
Rudolf Babitzka, Kirchberg, DE;
Wilhelm Polach, Moglingen, DE;
Walter Schlagmuller, Schwieberdingen, DE;
Robert Bosch GmbH, Stuttgart, DE;
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 hence to the valve stem (11).