Research And Design Of ECU Hardware Circuit For National VI Emission High Pressure Common Rail Diesel Engine

Automotive pollutants are one of the major contributors to atmospheric pollution.As China’s vehicle ownership continues to increase and the environment continues to deteriorate,in order to effectively control the emission of vehicle pollutants,China has successively formulated and implemented emission regulations for each stage,which was proposed in 2016.The national 6emission regulations for light-duty diesel vehicles are planned to be implemented in phases 6（a）and6（b）in 2020 and 2023 respectively.Electronically controlled high-pressure common-rail diesel engine can achieve flexible control of fuel injection pressure,fuel injection quantity,fuel injection timing and fuel injection law.The electronic control unit（ECU）hardware circuit is used as the carrier of the electronic control system.Therefore,the ECU hardware circuit is studied.It has important practical significance.For the medium-power high-pressure common-rail diesel engine and its after-treatment system,the Yunnei D20TCI is the control object,using Infineon’s AURIX^TM series 32-bit 3-core microcontroller（MCU）.The functional requirements of the ECU hardware circuit of the State6 high-voltage common rail diesel engine were analyzed.Several key technical problems of the ECU hardware circuit were analyzed in a theoretical analysis combined with the experimental verification method.The adjustment methods of the crankshaft and camshaft signals were used for fuel injection.Instrument,urea nozzle and fuel metering valve drive method.The results show that the crankshaft and camshaft signals use variable magnetoresistive sensor interface chip for signal conditioning circuit design to convert differential input signals to square wave signals;the injector adopts high and low voltage driving modes;the urea nozzle adopts the high-low single voltage driving mode;Fuel metering valves use low-side drive to meet functional requirements.A modular design method was used to design the ECU’s five major module circuits:MCU module peripheral circuits,ECU power supply module circuits,power drive module circuits,signal conditioning module circuits,and ECU communication module circuits.Among them,the power drive modules mainly include high pressure common rail injectors,fuel metering valves,glow plugs,urea nozzles,exhaust gas recirculation（EGR）,variable area turbocharger（VNT）,electronic throttle（ETC）,DPF oil injection device,wide-ranging oxygen sensor heater,electric heating of selective catalytic reduction（SCR）system,and water heater.The ECU printed circuit board（PCB）laminated structure,PCB layout and wiring,grounding,electrostatic discharge（ESD）protection design points were analyzed in detail,to meet the requirements of the PCB design.The ECU hardware circuit was tested using circuit function experiments and bench tests.The results show that the ECU hardware circuit meets the design criteria.Both the urea nozzle and injector drive currents achieve the ideal PEAK-HOLD waveform.Urea nozzle response time is less than 5ms,power consumption is less than 3.5W;within 100μs,injector drive current can be increased from 0A to 18A;60μs internal energy can be reduced from12A to 0A;switching from 18A to 12A within 80μs does not cause injector Shutdown,the crankshaft,camshaft signal conditioning circuit can convert the original signal into a no-delay,clean square wave signal,providing an accurate angle reference point for the high pressure common rail system to judge the cylinder.The fuel metering valve can adjust the common rail pressure in real time based on the common rail pressure signal fed back by the rail pressure sensor.