【作者】 吕成绪；

【导师】 张维强； 缪培仁；

【作者基本信息】 南京农业大学 ， 机械设计及理论， 2004， 硕士

【摘要】 发动机的动力性能是发动机技术状况的重要指标，其动力性能的好坏不仅能反映发动机的技术状态，而且还可以作为发动机进一步检测的依据。传统的发动机动力性能检测主要为台架式检测装置，需要将发动机安装在台架上，其缺点是一方面检测比较繁琐，另一方面其检测时加载后的运行状态与实际的工作负荷状态有一定的差异，从而会导致检测结果的差异。台架式检测装置不能进行实时检测。目前国内外常用的发动机动力性能实时检测系统是采用无负荷测功法，即通过加速后测定平均加速时间的方式来计算发动机的功率值。该方法的缺点是检测结果精度差，重复性差，同时无法根据功率状态进行加载，故具有明显的局限性。本文总结和汲取前人研究成果，针对洋马联合收割机设计开发了基于工业控制计算机的发动机功率实时检测系统。 该系统在洋马联合收割机的发动机动力输出与工作装置的动力输入轴之间安装了转速和扭矩传感器，对转速和扭矩传感器的输出信号进行V／F转换、放大等预处理，并计算出功率值。在设计中通过添加单片机弥补了数据采集卡所带的定时／计数器不够精确的缺陷，提高了系统的精度。 同时，洋马联合收割机工作环境恶劣，很容易受到各种干扰，本系统采用了光电隔离、接地、屏蔽、滤波等硬件措施，以及看门狗电路、数字滤波等软件措施，有效的降低了干扰，保证系统能正常工作，保证了检测结果的稳定性与正确性。 开发了一套以Visual Basic 6.0为软件平台的洋马联合收割机发动机功率实时检测系统。采用动态多文档技术，整个系统包括以下几个部分：密码模块、转速和扭矩的初始化模块、转速和扭矩实时波形显示模块、数据与报表模块以及帮助模块等。系统可以同时实现转速和扭矩的实时波形和数据显示，并将数据存贮到数据库中，可作为状态监测、故障诊断等后续研究之用。 系统设计完成后，利用频率发生器对系统精度进行检验。通过实验发现本系统精度很高，完全可以满足实际需要，具有很高的使用价值。 最后，本文介绍了本系统存在的一些不足之处以及需要补充及扩展的部分，对将来的继续研究做出了建议。更多还原

【Abstract】 The dynamic: performance of engine is one of important indexes of engine technical status. It can reflect engine technical status, and the further test can be done according to it. Engine test-bed experiment is the traditional main means of testing the performance of engines, which need the engine fixed on the test-bed. One of the shortcomings of it is inconvenient, and the other is the work status after being loaded when the engine is tested is different from what it is at actual work status. It cannot test the performance of engines in real time. Now the common means of testing the performance of engines in real time is noload dynamometer test, which computes the engine power by measuring the average accelerate time. The accuracy and repetition of it is low, and it cannot be loaded acfcording to the status. So it has obvious limitation. The power testing system in real time applied to Yanmar combine harvester with industrial control computer is studied in this paper on the basis of former achievements.In the system, the rotate speed sensor and torque sensor are fixed between the engine power output shaft of Yanmar combine harvester and the power input shaft of working device. The signals of torque and rotate speed are preprocessed such as V/F, amplified. And the power is computed. The bug, that data-acquisition card’s timer/counter is not accurate, is made up by adding Single Chip Micyoco. And the system’s precision is improved.Meanwhile, the working condition of Yanmar combine harvester is very foul, so the system is prone to be disturbed. Interference-free measures are taken on hardware such as optoelectric coupling, earth, screen and filtering. And measures on software such as watch dog circuit and digital filter were taken too. These measures ensure the system work normally, and ensure the result steady and accurate.An engine power testing software for Yanmar combine harvester based on Visual Basic 6.0 is developed. The software applies the technology of dynamic multipledocuments. It includes password module, initialization module, waves of torque and rotate speed display module, data and report forms module and help module. It can display the waves and value of torque and rotate speed at the same time, and the data can be saved in database as the reference information for status inspecting and malfunction diagnosis in the future.After the system is designed, frequency generator is used to test the precision of system. Through the experiments, it can be concluded that the precision of system is very high, and it can fit the actual requirement, and be of very valuable.At last, this paper also illustrates the shortage and some parts needed to add in of the system, and give some suggestion for the study on this topic in the future.更多还原