船舶柴油机冷却水温度控制系统.doc

本科生毕业设计（论文） PAGE PAGE II 本科生毕业设计（论文） PAGE 1 摘 要 船舶柴油机冷却水的温度是影响柴油机工作的重要热工参数。精确控制冷却水的温度，对于提高柴油机的动力性、减少废气的产生、减少燃料消耗量等方面都有着重要的意义。 本设计的单片机系统采用了AT89C51作为微处理器，采用铂电阻(pt100)作为温度传感器，与运算放大器(op27)相结合构成精密测温电路，采用了ADC0809芯片作为精密测温电路与单片机的转换通道。键盘矩阵采用2行3列非编码方式，显示部分为3位LED数码管显示，看门狗电路采用了较为常见的X25045芯片。系统输出环节通过单片机输出口传递输出控制信号，经光电藕合4N25和模拟开关CD4052后去控制继电器的通断，进而控制三相伺服交流步进电机电机的旋转，当实际温度偏高时，单片机输出控制信号使正转继电器通电，伺服电机正转，改变三通调节阀的开度，增加流过淡水冷却器的淡水量，使淡水温度降低;当实际温度偏低时，单片机输出控制信号使反转继电器通电，伺服电机反转，改变三通调节阀的开度，增加旁通冷却水流量，使淡水温度升高，最终起到温度控制的作用。 本设计引入了功率模糊控制信号的智能温度控制系统，有效地克服了水温的时滞特性，大大地降低了冷却水温度的超调量，并提高了系统的响应速度；采用屏蔽与隔离技术，提高了控制系统在恶劣环境中的抗干扰能力；采用指令冗余及数字滤波技术，提高了系统的软件抗干扰能力。 关键词：船舶柴油机；冷却水温度；单片机；数码管显示 Abstract The temperature of cooling water of marine diesel engine is an important reference. It is very significant to control the temperature of cooling water accurately. For improving the power performance of diesel engine, decreasing the exhausting and saving fiiel. The design of the SCM system uses AT89C51 as the microprocessor, using platinum resistance (pt100) as a temperature sensor, and operational amplifiers (op27) combined constitute precise temperature measurement circuit, using ADC0809 chip as precision temperature measurement circuit and microcontroller conversion channels. Keyboard matrix using two rows three non-coding mode, the display part of the three LED digital tube display, the watchdog circuit uses more common X25045 chip. System output link passing through the microcontroller output port output control signal, the optical coupling and analog switches CD4052 4N25 go after control relay off, and then control three-phase AC servo motor stepper motor rotation, when the actual temperature is high, the microcontroller output control signal forward relay is energized, the servo motor is transferred, changed way regulating valve opening, increasing freshwater flowing fresh water cooler, so that f