| With stringent emission standards and the non-renewable nature of petroleum,modern diesel engines have to achieve many performance standards related to fuel consumption,emissions,noise and vibration.Combustion control has a great influence on the economy and emissions of diesel engines.The diesel injection system is one of the key factors for combustion control.The fuel injection control valve is also a key device for controlling the fuel injection of the fuel injector.Therefore,high-performance marine low-speed engine injection is developed Piezo valves for oil control are very important and have a very important engineering application value,which helps to promote the development of electronically controlled fuel injection technology for marine diesel in China.The thesis takes the low-speed marine fuel injection system independently developed by a domestic company as the object.First,the structure and size of the piezoelectric valve for fuel injection control are designed,and the prototype is completed.Then,through the AMESim system modeling and simulation platform,the performance of the preliminary designed piezoelectric valve for fuel injection control was simulated.Finally,a piezoelectric valve performance test bench was developed,and the response and flow characteristics of the piezoelectric valve were tested and verified.The research work completed and the main conclusions obtained are as follows:(1)Analyzed the key technical index requirements of the piezoelectric valve for fuel injection control,combined with the existing technical research foundation of the research group,and completed the preliminary design of the piezoelectric valve.Mainly include piezoelectric valve main performance and structure parameter design,piezoelectric valve drive device selection design,valve body structure design,drive circuit design,reset spring design,etc.The piezoelectric valve adopts a two-position three-way ball valve structure,the diameter of the ball valve core is8 mm,the stroke is 0.35 mm,and the valve port diameter is 6mm;the driving device of the piezoelectric valve is the NAC2643 piezoelectric actuator of CTS.(2)The driver design of the piezoelectric valve was carried out,the AMESim simulation model of the piezoelectric actuator was established,and the influence of the basic parameters of the piezoelectric stack on the output displacement was analyzed.A performance test device for piezoelectric actuators was developed to test and analyze the influence of control voltage on the displacement of piezoelectric actuators and the influence of spring preload on the displacement of piezoelectric actuators.The test results show that the maximum output force of the piezoelectric actuator is250 N,the maximum displacement is 0.625 mm,and the response speed is 0.7ms.The performance of the piezoelectric actuator can meet the driving requirements of the piezoelectric valve.(3)The AMESim simulation model of the piezoelectric valve for fuel injection control is established,and the characteristics of fluid motion(flow field)and dynamic response during the operation of the piezoelectric valve are analyzed;the structural dimensions of different valve cores are compared to open the piezoelectric valve the effect of response speed.After comprehensive analysis,the structure size of the spool still takes the preliminary design value,the spool radius is 4mm,and the spool stroke is 0.35 mm.(4)Developed a piezoelectric valve performance test bench,and conducted an experimental study on the trial-made piezoelectric valve,and measured the switching response time and flow rate of the piezoelectric valve.The test results show that the opening response time of the piezoelectric valve is 0.72 ms and the closing response time is 0.65 ms,and its high-speed response performance far exceeds that of the traditional electromagnetic injection control valve;when the pressure difference of the piezoelectric valve is 30 MPa,the flow rate can reach 42L/min,which can achieve the actual requirements of the fuel injection control valve. |
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