Development Of Diesel Engine SCR System Management Software And Key Components

With the increasingly strict emission regulations,diesel vehicle emission pollution has become the focus of social attention.Many diesel engine factories and scientific research institutions have carried out a lot of research work.A lot of studies show that SCR technology has been one of the most effective way to meet the National IV emission regulations and above.The diesel engine SCR system comprises a plurality of electronic control units,the urea pump control unit DCU and nitrogen oxygen sensor ECU communicate with the Engine control unit through CAN bus,both of them are the core of the whole control system.Therefore,this paper will focus on the development of the hardware and software of urea metering pump and nitrogen oxygen sensor.The increasingly complexity of automotive electronic system has proposed new requirements for software development.In order to improve the real-time,portability and compatibility of the software,German auto industry jointly launched the OSEK standard.This paper followed the OSEK standard and a set of management software was developed based on Trampoline.On the basis of this software,we develop application program and configure the corresponding OIL file.The basic configuration file and the GOIL parsing file were merged to generate the whole application program.The development of application software can shorten the development cycle and reduce development costs,the portability and compatibility of the software are relatively better as well.In regard to nitrogen oxygen sensor hardware,the independent design and development of a nitrogen oxygen sensor ECU circuit board were carried out according to the working principle of nitrogen oxygen sensor.The circuit includes CAN communication module,MCU module,voltage converter module,heating and the signal processing module.In this paper,a new heating control circuit and a new method for nitrogen and oxygen sensor were proposed.Compared with existing solutions,this solution could reduce the use of constant current source,lower the cost and complexity of the circuit.Regarding the urea metering pump hardware,according to the domestic and foreign advanced achievements of SCR.An urea metering pump and the corresponding method of urea supply were provided.The dosing control unit(DCU)was intergrated as well.By adjusting the speed of the stepper motor according to the different conditions of engine to control the diaphragm pump,the supply of urea could be measured accurately.The input end and the output end of the device were respectively arranged on both sides.A pressure sensor is placed in the compressed air channel of the device.There is a solenoid valve in the urea return channel and the heating device is placed near the mixing chamber.The DCU is fixed on the cover of urea metering pump.The base of this device has simple structure which can reduce the cost largely.By testing the real-time and portability of the management software,results show that the developed management software can be applied to the development of various applications,the developed nitrogen oxygen sensor and urea metering pump can work normally.