The Development Of Measurement And Control System For A Loading Test Device Of Engine Accessories

With the increasing of the market competition and the user’s expectations of product quality and performance, the performance test and reliability test of engine becomes more and more rigorous. Engine bench test is an important means to test the performance of the engine. Through a lot of tests, it can test whether the engine performance meets the design requirements, and provide the basis and direction for the design and improvement.In order to make the engine bench test environment more close to the engine environment in vehicle road running, it is necessary for engine to use the load test device to load different power accessories in the prescribed engine conditions in bench test. In order to control the loading process of the power accessories and to monitor the working status of the engine and its power accessories in real time, this paper developed a measurement and control system of the engine accessories loading test device. The main contents are as follows:1) Based on functional requirements analysis, the loading mode and control mode of engine power accessories were determined, and the overall structure design of the system was carried out by using the control scheme of upper and lower computer. According to the loading requirements, the air conditioning compressor loading module, vacuum pump loading module, alternator loading module and steering pump loading module were developed. At the same time, the selection of actuators and sensors for each module was completed.2) A foreground measurement and control unit was developed based on NXP 16 bit dual core microcontroller. The functional modules of hardware system include analog signal conditioning, RS-232 serial communication, Ethernet communication, switching control module, etc. The embedded software was designed based on the principle of modularization and task scheduling mechanism. Task functions include vacuum pump loading control, air conditioning compressor load control, generator load fan control, servo motor control, A/D data acquisition, real-time interrupt, Ethernet communication, serial communication, etc.3) Background management software was designed based on the Visual Basic 6.0 programming environment and industrial control computer. It can distinguish the test conditions of the engine and work synchronously with the measurement and control system of engine bench test. The manual loading and automatic loading control of the power accessories were realized through the information interaction between the background management software and the foreground controller. Management software has a good man-machine interface, and its functions include user management, parameter setting, data communication, test status display, parameter digital and graphical display, data storage and dynamic playback, fault alarm, etc.4) On the engine test bench, the manual loading and automatic loading tests of power accessories were carried out. The results indicate that the system meet the requirements of the multiple engine accessories loading in the bench test, and it can stably and reliably control the loading of engine accessories, and can complete the engine test according to the test specification.