APPARATUS FOR SENSING SPEED ITSELF OF VEHICLE USING PIEZO-ELECTRIC EFFECT ELEMENT AND METHOD THEREOF

摘要

The present invention relates to a method and an apparatus for measuring the speed of a vehicle by detecting the speed of a vehicle by a piezoelectric element and analyzing and processing the detected signal. The apparatus comprises: a bracket which is fixated to the surface of a vehicle body and transmits vibration generated when the engine of the vehicle runs; a piezoelectric element fixedly coupled to the bracket to convert and output the vibration from the bracket into a voltage signal; a low pass filter to remove a high band frequency and noise among the voltage signal of the piezoelectric element; a shift ratio writer to compare the rotation number of a wheel over the rotation number in accordance with RPM due to gear shifting; and a speed measuring CPU to convert and output the rotation number received from the shift ratio writer and the low band frequency received from the low pass filter into a vehicle velocity in accordance with the gear shifting. The apparatus can be installed on a desired location of the vehicle body without deformation or decomposition of the vehicle, with a low manufacturing cost of designing and producing a circuit comprising the bracket, the piezoelectric element, the low pass filter and the speed measuring CPU. The apparatus can be easily adapted to various devices using the speed information of the vehicle, with improved accuracy and credibility of sensing the speed itself.