Development Of Common Rail Diesel Engine ECU Assistant Debug System

This project is one part of common-rail diesel engine development of FAW. The main content is to develop a set of intelligent debugging system according to the needs of FAW. This system can simulate and test the signals of the ECU facilitating the hardware and software debugging.Increasingly rigorous emission legislation and severe energy shortage force diesel to be developed for the objects of lower pollution, lower fuel consume and high power per weigh. However, the key to reduce emissions, improving diesel's power and fuel efficiency depends on improving diesel's combustion process. And among all of fuel injection system currently, diesel engine high-pressure common rail electronic control injection system is the most effective in emission reduction and engine performance improvement. The electronic control system is common rail diesel engine's core technology and hardware basic. The design of the electronic control system will have a direct bearing on the quality of the diesel engine.During the development of common-rail diesel engine ECU, we request the ECU can deal with the sensor signal in variety of environmental, to ensure that the diesel engine electronic control system can work reliably under all conditions. However, during the software and hardware debug of ECU, it is difficult to issue the original car signal and the various electromagnetic valves, relays, etc. for the debug. Based on these disadvantages, some well-known automotive electronics developing companies abroad has developed their related analog signal detection system, such as Motorola and Bosch have developed their products. But due to the confidentiality of foreign automotive electronic technology and high product prices, the domestic automotive manufacturers are very difficult to use it. Therefore, the development of a low-cost , intelligent test systems for analog signal ECU hardware and software testing has a very important significance.This paper search some relevant information of the common-rail diesel engine electronic control unit at home and abroad, and find out the various types of sensors and load of common-rail diesel engine ECU and also develop a set of intelligent assistant debugging system according to the needs of FAW.This system can be controlled by MCU, and be designed in modular concept. It is a multi-CPU assistant debugging system which is made up of a number of micro-controllers .This system can simulate some sensor signals of common rail diesel engine's ECU, including analog signal, switch signal, speed signal, crankshaft signal camshaft signal and so on. In addition, this system can test the control and display signal of ECU, including electromagnetic valve, relay signal and speed signal of the drive panel. This system can provide the CAN bus interface for ECU, simulate the CAN signal from other module, communicate with the ECU and know about the control information from ECU.This paper can simulate the adjustable frequency crankshaft speed sensor signal of hall style and camshaft speed sensor signal of magnetic-electric style, with MCU and related peripheral circuits, based on a detailed study of the hall sensor and magnetic sensor working principle and the basis of signal types. Crankshaft speed sensor signal is square-wave output with missing tooth structure. Its design is to use single-chip microcomputer in accordance with the frequency of the crankshaft signal calculated to achieve the turnover time. Camshaft speed sensor signal is the sine wave output with zero-point of identification. For camshaft signal output with the type of magnetic-electric, the design is to use MCU output the PWM signal with continuous duty cycle change, and through RC filter and the amplifier. This design has the characters of accurate output signal and simple hardware circuit. This is one innovation of this paper.At the same time, this paper simulate analog sensor signals which is the most common sensor signal of common-rail diesel engine ECU based on the referring to the relevant literature. There is a total of 16 analog sensor signals output. In this paper, the use of host microcontroller control ST7 MCU to output 16 adjustable duty cycle PWM signal through the SPI communication , and through the RC filter, amplifier, transistor emitter output, and taking fully account into the design of the system, such as short-circuit protection factors. Compared with the conventional D / A converters analog signals, the hardware design has a simple structure, low cost, reliability, etc. This is an innovative point of this paper.This paper also describes software design of the assistant debug system and main software modules of the system. This paper also describes the CAN communication design process in detail. The main control program of the Assistant debug system is modular design. That is, the system is divided into several functional modules. The main program only carry out scheduling function, and is responsible for calling the function module procedure. With the main cycle circling around, all the functional modules are called. The benefits of using this structure is all the modules are independent, and have clear procedures and simple logic.This paper also describes the CAN application-layer communication protocol and the CAN communication mechanism for receiving and processing of the assistant debug system in detail. About the CAN communication receive mechanism, this paper is use the interrupt and store the packet into the circle queue. About the CAN data process mechanism, the paper uses the method of inquiry flag in the main cycle. Idea of using the benefits of this design is separate CAN receive and CAN process, ensuring the reliability of the data communications and high-efficiency and avoiding the loss of packets.Common rail diesel engine ECU assistant debug system belongs to an intelligent tool for the automotive electronic development. It is a set of signal simulate and test system based on the common-rail diesel engine electronic control unit. It combines virtual instrument technology and field bus communications technology and so on. The framework is designed in blocking. And it breaks the complicated system into some relatively simple systems, provided with adequate hardware and software support. Through the use of assisted human-computer interaction interface, debugging system can simulate various sensor signals and detection of various common-rail diesel engine loads conveniently and quickly.