| Since the diesel engine came out, it has developed over one century and it has already made the great progress on overall technology. The diesel engine plays the irreplaceable role in each profession's power machine, and also occupies dominant status in the ship power. Presently diesel engines are used as the main engine on most ships.Among all equipments on a ship, the main propulsion diesel engine is the ship's important component, and is also the source of power to propel the ship. It plays an irreplaceable role in the ship movement. After the diesel engine works in long time, the mechanical fault, the heat from bearing and so on can cause the crankcase giving off heat seriously, which will vaporize the lubricating oil to produce the high-temperature oil gas. After the oil gas cools, it forms the oil mist. In a high temperature environment the excessively high density of the oil mist will cause the diesel engine crank case to explode, which will create the economic loss and the personal injuries.As early as 1960, the first oil mist density detector used in marine diesel engine crankcase was invented in Britain. With the development of ship industry, the functions of the detector have been constantly improved, but there are still many problems such as the relatively slow reaction rate, the low digitized degree as well as no communication with the entire ship monitoring system and so on, which can not meet the demand of modern ship. In this paper, a design of the oil mist density detector based on the DSP (Digital Signal Processing) was proposed. The corresponding research was made.The design in this paper is based on the method of traditional oil mist density detector. The function of oil mist density detector designed in this paper meets the specifications of The classification and construction regulation for steel ship. In this paper the hardware and software designs of control section were finished, and functionality experiment confirmation was carried out.The following work was made in this paper:(1) The factors and conditions of causing the high oil mist density and explosion in crankcase were analyzed, and the effects that equipment failure, crank case temperature and pressure and so on cause explosion in the crank case were analyzed.(2) The hardware designs of the oil mist density detector were completed, including power supply, AD acquisition module, analog input, digital input and output, communication module, sampling solenoid valve control circuit, alarm display circuit and various experiment and test modules.(3) The software of the oil mist density detector was designed, including various algorithms and module programs, so oil mist density detector meets the demand of The Classification and Construction regulation for steel ship.(4) The interface program was achieved, and the functions of interactive communication between man and machine and data storage were accomplished.(5) The related functional experiments were made after completing the design, and the experiment results meet the desired requirements. |
