Research And Design On Drive Characteristics Of Hydraulic Exhaust Valve System For Small Bore Low-speed Diesel Engine

In order to reduce environmental pollution,improve the economy,and ensure that the diesel achieve optimal distribution under different work conditions,adopting new exhaust system is the inevitable trend in the development of modern diesel.Variable valve technologies is one of the hot research direction to improve the performance of engine,one of them,the electro-hydraulic no cam driven exhaust system compared with the traditional system has the advantages of light,flexible layout,adjusted timing,and single valve controlled independently.It is meaningful to design and optimize the structure of exhaust valve system.This article analyses operating principle of diesel engine hydraulic exhaust valve system,establishes the numerical simulation model for the small bore low-speed diesel engine hydraulic no cam driven exhaust system,and analyses the performance of the exhaust valve with the simulation model,including servo oil rail,valve control unit and exhaust valve components,etc.By comparing the simulation model results with relevant data,the model accuracy had been verified.Secondly,to research valve open delay,valve close delay and valve maximum lift as the object of study,Paper analyzes the dynamic response of the exhaust valve under the influence of the different servo oil rail pressure,engine load and the characteristic parameters.By application of quantitative analysis,research on influence to the valve open delay,valve close delay and valve maximum lift can be develop.Results show that the secondary piston diameter,hydraulic tubing diameter,valve hydraulic piston diameter and air spring piston diameter are the main factors that influence the dynamic response of the exhaust valve.Finally,in view that the double-piston hydraulic driven exhaust valve has disadvantage of larger displacement fluctuations and collision impact force,this paper designs a three-piston driven hydraulic exhaust valve system and establish the simulation model.Exhaust valve dynamic response characteristics are analyzed under different working conditions,and dynamic response speed is compared between new design and the traditional double-piston hydraulic exhaust valve system.Compared with the traditional double-piston driven exhaust valve,three-piston driven exhaust valve can make the exhaust valve opens more rapidly,reduces the open delay,effectively reduces instantaneous speed of the moving component during the collision,the force from collision impact in the working process,and the size of the lift maximal peak value,lift fluctuation in the subsequent also get down.