Research And Design Of Multi-point Injection Gasoline Engine ECU Hardware Circuit

Based on the practicality of multi-point injection gasoline engine in the intake port,this paper analyzes the domestic and international research status of multi-point injection gasoline engine ECU and its adaptability to the latest emission standards in China.The use of discrete components combined with the current popular high-integration engine management chip solution.The ECU hardware circuit of the multi-point injection gasoline engine of the inlet is designed and the hardware modular test is carried out.The detailed ECU hardware scheme of the multi-point injection gasoline engine of the inlet is designed,including the selection of each power device,the selection of the MCU and the resource allocation of the MCU pins.The entire ECU power module was analyzed in detail,and the MCU power module,sensor power module and power device power module were designed.Detailed requirements analysis was performed on the sensors required for the multi-point injection gasoline engine of the inlet,including sensor type,principle,signal type,power supply parameters and signal output range.The corresponding conditioning circuit is designed,and the signal generator is used to perform signal offset test at different frequency states.The test results show that the sensor conditioning circuit meets the design requirements.Detailed requirements analysis was performed on the actuators required for the multi-point injection gasoline engine of the inlet,including the type of actuator,the drive mode and the operating voltage.Based on the electrical characteristics of electronic throttle,EGR valve,idle valve,OCV valve,ignition coil,fuel injector,canister solenoid valve,fuel pump motor,oxygen sensor heater and relay,the corresponding drive mode and drive components are selected.The drive circuit of each actuator is designed.The fault diagnosis principle and implementation method of the fuel injection system,ignition system and H-bridge motor control system integrated chip are analyzed in detail.The scheme analysis of the ECU’s PCB selection four-layer board is given,and the layout points and wiring precautions of the PCB in the complex system of the gasoline engine ECU and the difficulties encountered in the layout and routing are explained.The interference problems caused by the grounding design and the power layer design are analyzed in detail,and how to avoid them,and the circuit for setting the isolation band is used to guide the current on the PCB.The necessity of manual welding for the initial ECU commissioning is briefly described.On the basis of the completion of the schematic diagram,the design of the ECU hardware PCB is completed and made by the plate making manufacturer.After the PCB was completed,the components of each module were soldered by hand and hardware debugging was performed.The signal waveforms of each module were tested.In the absence of the test bench,the signal conditioning module,the fuel injection module,the ignition module,and the motor drive module worked normally and met the design requirements.The hardware-in-the-loop test was performed on the fuel injection system.The injector solenoid drive current reached 1.5A at 500μs.After the driving control signal was continuously shaken,the current of the injection solenoid valve could be maintained at about 1A.After the Hold phase is completed,the injector solenoid valve is quickly shut down within 150μs,and the load current is feedback controlled by the hardware circuit,which can maintain the current waveform well.