Design Of Solenoid Valve Of Electronic Controlled Injector For Marine Diesel Engine

Electronic-controlled high pressure common rail fuel injection technology is oneof the most promising technologies of a diesel engine. Because it could reduce NOxand Soot emissions of the diesel engine and improve the fuel economy simultaneously.In the common rail system, the solenoid valve controls the injector’s action accordingto the fuel injection signal from the electronic control unit (ECU), and thus realizesthe flexible control of fuel injection. The response speed of the solenoid valve needsto be fast enough in order to accurately control the injection timing, the injection du-ration and the multiple injections. The flow capacity of the solenoid valve needs to belarge enough to guarantee the needed cycle fuel injection quantity for marine largepower diesel engine in all its working range. However, the response speed and theflow capacity of the solenoid valve are paradoxical. To increase the flow capacity,either spoon diameter or stroke needs to be enlarged, which in turn slows down theresponse speed. In order to meet the demand of the electronic-controlled fuel injector,the solenoid valve is designed and optimized through calculation method. The relatedresearch work and conclusions are as follows：First, the solenoid valve is intended to realize the injection control of the elec-tronic-control hydraulic intensified injector for a marine two-stroke low speed dieselengine, which demands for the specific flow capacity and the response speed of thesolenoid valve. The diameter and stroke of the valve spool is determined according tothe flow capacity needed, and the structure parameters of the solenoid is determinedaccording to the response speed needed together with the spool stroke by applying themagnetic circuit calculation method.Second, an electromagnetic field finite element model of the solenoid is estab-lished on Ansys Maxwell platform. The parameters of the solenoid, including the corematerial, the pole number, the outer diameter and the thickness of yoke and armature,have on influence on the electromagnetic force. They are studied through paramete-rized static magnetic field finite element analysis of the solenoid. All the parametersare optimized based on the research results. Transient magnetic field simulation of thesolenoid optimized is carried out with voltage excitation equal to the injection pulse width and load force similar to the valve hydraulic force applied. The simulation re-sult revealed a clue of the opening and closing response time of the solenoid valve,and the influence of the core eddy effect on the inner distribution of the flux density.Third, the dynamic model of the entire solenoid valve, including the solenoid,the PI controlled H Bridge driving circuit and every detail of the valve, is establishedon AMESim platform. The simulation result of the dynamic model revealed the elec-tronic，the magnetic，the mechanical and the hydraulic coupling relationship in thesolenoid valve working process. The diameter and stroke of the spoon is optimized toreach a faster response speed using the dynamic simulation method.Finally, the performance of designed solenoid value is analyzed through dynam-ic simulation. The influence of the current set value, including the trigger current andmaintain current, on the response time of the solenoid valve is analyzed, and the bestcurrent set value can be determined. With this current set value, the solenoid valvecan open in less than1ms and close in less than2ms, within its operating pressurerange (200bar to300bar). As for the multi-injection control ability of the designedsolenoid valve, the minimum opening pulse width is less than1ms, the minimumopening interval is less than2ms. It is concluded that the flow capacity, the responsespeed and the working frequency of the solenoid valve designed meet the demand ofthe flexible fuel injection control.