一种高性能价格比的汽车超速报警系统

An overspeed alarm system for automobile with high ratio of performance to price

设计了一种以频率/电压转换芯片LM2917为核心的高性能价格比的汽车超速报警系统。分析了系统电路的工作原理,给出系统的印刷电路板图,并测试实际超速报警车速与其设置报警车速相对误差的数据。系统设置5档超速阀值选择功能,可根据实际情况手动设置阀值。当汽车行驶速度超过设置报警阀值时,蜂鸣器能准确可靠的发出报警声及时提醒驾驶员减速,以减少因超速而发生交通事故。实验表明该系统相对误差小于0.40%,精度较高。系统结构简单、工作可靠、成本价不高于30元人民币,性能价格比高。已在四川丰田柯斯达TRB53L-ZEMSK型中巴汽车上得到了很好的应用,通过改变LM2917第7脚外接上拉电阻的阻值,可广泛应用于不同车型的汽车,具有较好的通用性。

An overspeed alarm system for automobile with high ratio of performance to price was designed by using the chip of FVC LM2917. In this paper, the working principle of system circuit is analyzed and the printed-circuit-board graph is present. Meanwhile, the data related to relative error between alarm speed actually measured and alarm speed setted is obtained. The system sets selection functions of 5 overspeed threshold values with manually setting-up in accordance with practical circumstance. When the speed of automobile is higher than the alarm threshold set value, the buzzer emits alarm sound properly and reliably in time to remind driver to slow down automobile in ease traffic accidents owing to overspeed. It is demonstrated by experiment that the relative error of the system is less than 0.4% and the precision is better. Because of simple structure, working reliability, low cost with less than 30 RMB and high ratio of performance to price, the system has been applied well to medium bus-TRB53 L-ZEMSK of ToYoTa automobile in Sichuan province. In addition, by changing the value of the pull-up resistor connected externally with 7th pin of LM2917, the system can applied to automobile with different types, so the system is of good transferability.