Massachusetts Institute of Technology

Woo Sok Chang

Kamal Youcef-Toumi

John G Kassakian

Thomas A Keim

The present invention provides a means to reduce holding current and driving current of EMVD's effectively and practically and to provide soft landing of a valve. The invention incorporates a nonlinear mechanical transformer as part of an EMVD system. The nonlinear mechanical transformer is designed for the spring and the inertia in the EMVD to have desirable nonlinear characteristics. With the presently disclosed invention, the holding current and driving current are reduced and soft valve landing is achieved. The nonlinear characteristics of a nonlinear mechanical transformer can be implemented in various ways. The concept of the invention can be applied not only to EMVD's but also to general reciprocating and bi-stable servomechanical systems, where smooth acceleration, soft landing, and small power consumption are desired.

Electromechanical valve drive incorporating a nonlinear mechanical transformer

A high precision friction drive positioning stage system is described. The friction drive positioning stage system uses three special actuation systems, each having a tip in contact with the stage and being capable of generating directional elliptical motion which allows the stage to move in any direction in the plane of the stage and in rotation. In one embodiment, each actuation system includes a plurality of piezoelectric elements in contact with a hat-shaped element at which the tip of the actuation system is located.

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Lexington, MA, United States of America

Woo Sok Chang