Development of a Novel Parallel-spool Pilot Operated High-pressure Solenoid Valve with High Flow Rate and High Speed

High-pressure solenoid valve with high flow rate and high speed is a key component in an underwater driving system.However,traditional single spool pilot operated valve cannot meet the demands of both high flow rate and high speed simultaneously.A new structure for a high pressure solenoid valve is needed to meet the demand of the underwater driving system.A novel parallel-spool pilot operated high-pressure solenoid valve is proposed to overcome the drawback of the current single spool design.Mathematical models of the opening process and flow rate of the valve are established.Opening response time of the valve is subdivided into 4 parts to analyze the properties of the opening response.Corresponding formulas to solve 4 parts of the response time are derived.Key factors that influence the opening response time are analyzed.According to the mathematical model of the valve,a simulation of the opening process is carried out by MATLAB.Parameters are chosen based on theoretical analysis to design the test prototype of the new type of valve.Opening response time of the designed valve is tested by verifying response of the current in the coil and displacement of the main valve spool.The experimental results are in agreement with the simulated results,therefore the validity of the theoretical analysis is verified.Experimental opening response time of the valve is 48.3 ms at working pressure of 10 MPa.The flow capacity test shows that the largest effective area is 126 mm2 and the largest air flow rate is 2320 L/s.According to the result of the load driving test,the valve can meet the demands of the driving system.The proposed valve with parallel spools provides a new method for the design of a high-pressure valve with fast response and large flow rate.

Is it the time to reconsider the choice of valves for cardiac surgery： mechanical or bioprosthetic？

Valvular heart disease is a pathologic process involving one or more of the four valves(aortic,pulmonary,mitral and tricuspid)of the heart typified by stenosis or regurgitation and leading to patient symptoms.The most common causes are tissue degeneration,rheumatic fever and congenital heart diseases.Aortic valve replacement(AVR)using either mechanical or bioprosthetic(tissue)valves via open-heart surgical

发动机可变气门正时阀的微分先行的PID控制算法

为优化发动机可变气门正时(VVT)阀原有的控制,提出了微分先行的比例积分微分(PID)控制算法。分析了VVT阀的工作原理与机械结构,测定了VVT阀的关键参数。建立了数学模型与Simulink仿真模型,借助于Matlab/Simulink平台。用实机平台与仿真平台,验证所提出的控制算法。结果表明:在VVT阀控制中,面对目标期望值的波动,与传统PID算法相比,在阶跃测试时,微分先行PID算法超调量降低0.8%,静态误差降低0.15%;在追踪测试时,其超调量降低1%,静态误差降低0.15%。因此,本算法完成了对VVT阀的优化控制。

Diesel Engine Fault Diagnosis with Vibration Signal

When the vibration of diesel engine structure is measured, the signal is composed of a very complex superposition of the contributions of different vibratory sources modified by their respective transmission paths. These sources originate from several internal phenomenon in the engine such as combustion pressure variation, unbalanced reciprocating and rotating parts. In a diesel engine, movement parts work in a specific order. Once the starting point is determined, occurrence of work order in different cycle phases can be determined. This could successfully use to identifying of impulses in complex vibration signal of a diesel engine. From the variation of features of those impulses, it is possible to determine the working condition of the engine. This can use to fault diagnosis of diesel engine, specially faults related to combustion process.

Design of a hybrid magnetomotive force electromechanical valve actuator

We propose a novel axis-symmetric modified hybrid permanent magnet(PM)/electromagnet(EM) magnetomotive force actuator for a variable valve timing camless engine. The design provides a large magnetic force with low energy consumption, low coil inductance, PM demagnetization isolation, and improved transient response. Simulation and experimental results confirm forces of about 200 N(in the presence of coil current) at the equilibrium position and 500 N(in the absence of coil current) at the armature seat. We compared our proposed design with a double solenoid valve actuator(DSVA). The finite element method(FEM) designs of the DSVA and our proposed valve actuator were validated by experiments performed on manufactured prototypes.

Effects of fuel combination and IVO timing on combustion and emissions of a dual-fuel HCCI combustion engine

This paper experimentally and numerically studied the effects of fuel combination and intake valve opening(IVO)timing on combustion and emissions of an n-heptane and gasoline dual-flicl homogeneous charge compression ignition(HCCI)engine.By changing the gasoline fraction(GF)from 0」to 0.5 and the IVO timing from-15°CA ATDC to 35°CA ATDC,the in-cylinder pressure traces,heat release behaviors,and HC and CO emissions were investigated.The results showed that both the increased GF and the retarded IVO timing delay the combustion phasing,lengthen the combustion duration,and decrease the peak heat release rate and the maximum average combustion temperature,whereas the IVO timing has a more obvious influence on combustion than GF.HC and CO emissions are decreased with reduced GF,advanced IVO timing and increased operational load.