汽车挂车电磁制动器的控制系统

CONTROL SYSTEM OF ELECTROMAGNETIC BRAKE USED ON TRAILER

旅游挂车与主车的制动不协调是长期以来阻碍拖挂式房车发展的主要原因,电磁制动器的应用可有效地解决这一问题。研究电磁制动器的关键部件——制动器的控制系统,它可通过主挂车连接处的小变形信号来判断挂车所需的制动力。A/D数据采集卡把从应变片采集到的模拟信号转化为数字信号,计算机将获取的数字信号进行运算处理,应用到制动器的控制算法中,得到的控制量作为定时/计数器的初始化值。定时/计数器的8253芯片被初始化后可以叠加形成两路输出的脉宽可调(PWM)信号。信号输出给半导体金属氧化物(MOS)开关控制电磁制动器的电压,从而实现对挂车制动力的控制。电磁制动器的控制系统整车制动试验表明,可根据主车制动情况的变化实时控制挂车制动力。

The disharmonism of brake system between the travel-trailer and the car is the main reason which has blocked the development of travel-trailer for a long time. The application of electromagnetic brake can solve that problem well. The control system of electromagnetic brake is studied. The brake system can recognize the magnitude of the braking force which the trailer needs by the tiny deform of the joint between trailer and car. Analog signals collected by strain gages are translated into digital signals by A/D board. Computer operates the digital signals with control arithmetic and the result is used to initialize timing/counter board. After being initialized, the 8253 CMOS of timing/counter board can output two routes pulse width modulation （PWM） pulse signals. The signals are exported to metal-oxide-semiconductor （MOS） switch to control the voltage of electromagnetic brake. Then the braking force of trailer can be controlled. Experimentation proves that the control system can adjust trailer＇s braking force in time.