Directly actuated valve with a strain-type actuator and a method of operating same

Abstract

Disclosed is a method of operating a directly actuated valve that comprises a strain-type actuator to actuate a valve member to travel between a closed position and an open position, the method comprising transmitting displacements from the strain-type actuator to the valve member, maintaining a compressive stress on the actuator that is greater than a predetermined minimum stress by applying a pre-load compressive stress and limiting to less than predetermined limits at least one of: (a) acceleration and deceleration of the valve member when moving between open positions and the closed position; and (b) velocity of said valve member immediately before contacting the valve seat. One of the preferred techniques for limiting the velocity of the valve member while also reducing the amount offluid that flows through the valve during the closing time, comprises changing the closing rate of the valve member so that the valve member travels most of the closing distance quickly during the beginning of a closing movement, and then slowing down the closing rate of the valve member in a second portion of the closing movement, so that the velocity of the valve member is less than a predetermined limit immediately before contacting the valve seat.

Description

technical field [0001] The present invention relates to a directly actuated valve with a strain gauge actuator, and a method of operating the same. There are many applications today which benefit from fast acting direct actuated valves, and in order to illustrate the advantages of the invention it is described herein, for example, in relation to one application which is particularly suitable, namely the direct injection of fuel into the combustion chamber of an internal combustion engine middle. Background technique [0002] The internal combustion engine has been used to generate power and drive machines throughout the centuries. Since its inception, internal combustion engines have undergone many improvements to become more efficient, more powerful and / or less polluting. Under some conditions, fuel combustion within the combustion chamber may be incomplete, which reduces efficiency and produces undesired emissions of unburned fuel. [0003] By having more precise contro...

AI Technical Summary

Problems solved by technology

Therefore, while it is desirable to close the injection valve quickly, there is also a need to reduce the impact of the needle on the valve seat in the case of direct actuated fuel injection valves operated by strain gauge actuators due to the possibility of damage to the actuator. force

The fastest closing time is not optimal if excessive stress is created on the actuator and other components

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