JPS6461884A - Ultrasonic-system vehicle sensor - Google Patents

Abstract

PURPOSE:To receive only a primary reflected wave regardless of the constitutions of the bottom of an elevated road and a circumferential environment, by fitting a reflecting plate, which is in an inclined condition for the turnaround wave direction of an ultrasonic wave, at an vehicle passing on a road, and folding and reflecting the reflected wave returning near the circumference of an ultrasonic wave echo sunder transducer. CONSTITUTION:When an ultrasonic wave X1 is transmitted from an ultrasonic wave transceiver 4, a primary reflected wave H1, which is reflected by a road surface R or the passing vehicle and returns, is received by the ultrasonic wave transceiver 4. At such a time, a reflected wave H1 has a slight diffusion, and returns near the circumference of a transceiver 2, on the other hand, when an inclined reflecting plate 5 with an inclination angle of 45 deg. is provided at the vehicle, the wave H1 is reflected in a vertical direction, and does not reach the road surface R or the bottom L of the upper elevated road. Consequently, the secondary or tertiary reflection is not generated, too, and the measuring accuracy is improved. Here, the inclination angle is allowable at 20-60 deg.,, and when sponge or glass wool is stuck on a reflecting plate 5, and external sound is absorbed, and a sensing function is improved.