Development of a Sensor-less Electro-Hydraulic Valve Actuator for a Cam-less Engine

Abstract

A fully electronically controllable valve-actuator has potentials of improving volumetric efficiency at gas exchange, and of presenting variable compression-ratio. This paper describes a new type of hydro-mechanical position-servo electro-hydraulic valve actuator for a cam-less engine. The piston is positioned hydro mechanical feedback mechanism, which balances the flow rate of the feedback slot to the pilot valve. The feedback-slot opens its area in proportion to the piston displacement. This mechanism succeeds to decelerate the landing-velocity of 0.2m/s at a working speed of 1.0m/s for valve lift of 12mm, and to actuate the valve at a volumetric efficiency of 95% within lag times of opening 18ms and closing 8ms, that is possible to work at an equivalent engine rotational speed of 2100rpm. The actuator is energized by the hydraulic power source of flow-rate of 6.7L/min and pressure of 14MPa.