Electrohydraulic drive

Abstract

Abstract High-speed injection valves have recently incorporated hydraulic lift transformers consisting, for example, of a pressure piston (DK) driven by a piezo-actuator (P) and a reciprocating piston (HK) connected to the valve needle (VN) and mounted for axial displacement in a pressure piston bore (ZY). This design places great demands on the individual components with respect to axial symmetry and dimensional accuracy, which complicates mass production of the valve and makes manufacture more expensive.The present application describes a drive that consists of a piezo-actuator (P) and a hydraulic force/travel ratio and that is compact and relatively economical to manufacture. To ensure the requisite axial symmetry of the drive despite production-based tolerances, a balancing element (AE) is mounted between the piezo-actuator (P) and the lift transformer, supported in a frustoconical recess (WL) in the pressure piston. This element (AE), which is shaped as a sperical segment of two bases and is made from special steel, can slide freely on the piezoceramic during the hydraulic buildup and thus can compensate a nonconcentric alignment of actuator (P) and pressure piston (DK). The free rotatability within the abutment (WL) also ensures that the upper part of the actuator (P) always maintains full surface contact with the pressure piston (DK). The drive is used in injection valves, pumps, etc.

Inventors

• 👤 Andreas Kappel
• 👤 Randolf Mock

Bibliographic Details