【作者】 马辉；

【导师】 朱瑞祥；

【作者基本信息】 西北农林科技大学 ， 农业机械化工程， 2010， 硕士

【摘要】 喷油器是发动机的核心部件,其性能对发动机的动力性、经济性、排放性有着重要的影响。目前,我国喷油器质量检测普遍采用人工方法,借助传统的手动泵和压力等工具进行检测,存在主观性大、操作不方便及检测精度不高等问题。改善现有喷油器性能检测技术,对提高喷油器出厂合格率、降低发动机尾气排放以及燃油消耗具有重要意义。本文分析了喷油器各种故障及其对压力波形的影响,借助电子技术、传感器技术以及信号处理技术对压力波形进行处理,设计了一套通过提取高压油管内压力波形特征参数对喷油器性能进行检测的系统。得出如下主要结果及结论:(1)针对喷油器性能检测行业存在的问题,以单片机为微控制器,以压力波形为研究对象,设计了一套喷油器性能检测系统。(2)霍尔传感器采集发动机转速信号,通过递推平均滤波法去除转速信号中的噪声,从而获得发动机转速,并以发动机转速为依据确定压力信号的采样频率。(3)外夹式压电传感器采集高压油管内压力信号,通过小波变换法去除高压油管振动等噪声,得到纯净的压力信号,再运用符号描述法从纯净的压力信号中提取启喷压力、最大压力以及二次启喷压力等压力特征参数。(4)完成了本系统硬件电路设计,主要包括单片机微控制器、外夹式压电传感器、霍尔开关传感器、数据处理电路、A/D转换电路、外部存储器扩展电路、LCD显示电路、声光报警电路、键盘电路、电源电路、时钟及复位电路等。用面包板搭建了实际电路。(5)完成了本系统软件设计,主要包括初始化模块、发动机转速测量模块、压力信号采集及A/D转换模块、压力波形特征参数提取模块、外部存储器读写模块、LCD显示模块、键盘以及声光报警模块等。运用C语言编写了相应的软件程序。(6)通过Keil与Proteus联合对系统进行了调试和仿真,设定发动机实际转速为1000r/min,系统检测到的转速为999r/min;提取了压力波形及启喷压力P0、最大压力P1、二次启喷压力P2三个特征参数;借助实际硬件电路中对整个系统进行了验证。实验结果表明,通过提取高压油管内压力波形特征参数来检测喷油器性能的方案可行,实现了预期喷油器性能检测功能。更多还原

【Abstract】 Injector has an important effect on engine power, economy and exhaust emission. However, the way to test injector in our county lags behind, by using hand pump to test injector, there is great subjectivity, not high detection precision and inconvenient use. It is necessary to improve injector testing way in order to enhance injector passing rate,control engine exhaust emissions and reduce energy consumption.This paper analyzes the various faults of injector and its impact on the pressure wave, and design an injector testing system based on high-pressure in the pipe with electronic technology, sensor technology and signal processing technology. Main results and conclusions are as follow:(1)According to the main problems in the injector testing line, design an injector testing system whose microcontroller is MCU and study object is pressure wave.(2)Hall sensor is used to test engine speed, recursive average filter is used to filer noise, and then get engine speed. Determine sampling frequency according to engine speed.(3)Piezoelectric sensor clipped on outside of pipe is used to test pressure, wavelet transform is used to remove noise in order to get sheer pressure wave signal. Symbolic method is used to extract opening pressure, maximum pressure and secondary opening pressure from sheer pressure signal.(4)Complete the design of system hardware, mainly included MCU microcontroller, external clip-on piezoelectric sensors, Hall switch sensor, data processing circuit, A / D converter circuit, the external memory expansion circuit, LCD display circuit, sound and light alarm circuit , the keyboard circuit, power circuit, clock and reset circuit. Bread board is used to build actual circuit.(5)Complete the design of system software, mainly included initialization module, engine speed measurement module, the pressure signal acquisition and A / D converter module, the pressure waveform feature extraction module, external memory read and write modules, LCD display module, keyboard, and sound and light alarm module. Use C language to design software program. (6)By the combination of Keil and Proteus system debugging and simulation, set the actual engine speed 1000r/min, the system detects the speed 999r/min; extract the pressure wave and three characteristic parameters ,the opening pressure P0, the maximum pressure P1, secondary opening pressure P2.the actual hardware on the system was verified. The results show that high-pressure tubing to the pressure by extracting the feature parameters to detect the waveform performance of the injector is feasible, to achieve the desired detection performance of the injector.更多还原