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

摘要

An electronically controllable valve-actuator has the potential to improve volumetric efficiency and also realize a variable compression ratio engine. An electro-hydraulic actuator [1] has the characteristic of high force density, but working speed is usually relatively slow at limited power, as compared to an electro-magnetic actuator [2]. This paper describes a newly designed hydro-mechanical position control actuator for a 2800rpm cam less engine. The actuator positions the valve without using an electronic position sensor. The position is controlled by using a hydro-mechanical feedback slot. It has a function that reduces the landing speed. The stability of the hydro-mechanical position control mechanism is examined by both linear theory and bond graphs analysis. It expresses both power waste and landing speed simultaneously. A prototype has been designed to actuate a valve of 200g mass with 12mm in displacement, with a delay of 10ms; closing is executed under a landing speed of 0.1 m/s at a supply pressure of 14MPa.