Abstract
Keywords: Transient data acquisition, Diesel, Start voltage, Start electric current, Start rotational speed
Along with the increasing strict of the emission control regulations on automobile, it is stringent and important to control the emission of the cool-starting diesel engine, simultaneity, transient performance is profoundly researched on the diesel engine for vehicles; it is more and more important that the transient data acquisition systems of the cool-starting diesel engine have high-precision and high-frequency. At present, there are many methods at acquiring transient datas of the engine (1), (2), (3), (4).Which are applied on the immovable engine laboratorial platform. in the cool-starting process, to the transient parameters of the start motor on the start voltage and the start electronic current, their transient fluctuant rates and values are changed very rapidly, and their signals are required very highly in-phase. So the ordinary data acquisition apparatus can't achieve the needs on the on-line acquisition and deal of the cool-starting experiment in the diesel engine.
In order to carry out the transient parameter acquisition of the cool-starting diesel engine and roundly understand the work characteristic of the diesel engine and its accessorial equipments on the cool-starting, so it is necessary to develop a data acquisition system for researching the cool-starting performance of diesel engine. Based on these aspects, the portable data acquisition system which can acquire the dynamic parameters of the cool-starting diesel engine has been developed. Based upon the transient data acquisition systems of the diesel engine, the dynamic process of the diesel engine is tested and researched on the cool-starting, several dynamic parameters of the diesel engine about temperature, starting voltage, starting electric current and starting rotate speed are measured on the cool-starting. The test results show :( 1) At 5℃A after top dead center, initial stage of the diesel engine is started ; the variation of the start rotational speed is about 25%, the whole start process time is 15℃A, about 7.8 second, the maximum temperature variation of the cooling fluid is 0.5℃during the cooling start of the diesel engine; the maximum decreasing value of storage battery instantaneous starting voltage is 1.8V and the temperature variation range of the storage battery is minimum, about 0.4℃.All of these are accorded with the facts. (2) The maximum starting electric current is 678A, the minimum starting voltage is 9.3V, the maximal starting torque is 200 N·m, which completely satisfy the performance requirements of the cool-starting diesel engine. (3) The variation of the start voltage is 30%, and the start electric current is 25%, the reason is that the electrolyte conglutination of the battery is bigger at low temperature, so that the internal resistance of the battery is increased. The regulation and the variation of instantaneous parameters can meet the cool-starting diesel engine greatly. (4) It is reliable that the transient data acquisition systems and its signal deal circuit can carry out real-time collection, display, storage and analysis. It can be easily controlled by interface and demarcate program. It can meet the needs of the dynamic data acquisition for the cool-starting diesel engine greatly.