US 5,521,594 A · Road surface condition detector for automotive vehicle

Abstract

A road surface condition detector for detecting a dry/wet condition of a road surface includes an ultrasonic wave receiver 2 for picking up the ultrasonic noise generated by a road wheel tire 1, which increases conspicuously when the R is wet. The output of the ultrasonic wave receiver 2 is amplified by a amplifier 21, and the absolute level thereof is detected by an absolute level detector 22, and the absolute level is smoothed by a received-wave intensity detector 20. The smoothed signal is compared with a reference voltage Vt to determine the road surface condition. Preferably, the reference voltage Vt is varied in accordance with the vehicle speed. When the automotive vehicle is provided with ultrasonic wave transmitter/receiver units 3a and 3b, the ultrasonic noise component is extracted from the received signal by an ultrasonic noise intensity detector circuit 40, and the extracted component is compared with a reference voltage level to determine the road surface condition.

Claims15

Dependent claims

A road surface condition detector for an automotive vehicle for detecting a dry/wet condition of a road surface, comprising:

receiver means mounted on a body of an automotive vehicle for receiving ultrasonic noise generated by a road wheel tire of said automotive vehicle, said receiver means being arranged on the body so as to be directed toward a contact surface between said road wheel tire and a road surface;
intensity detector means, coupled to said receiver means, for detecting an intensity of said ultrasonic noise from an output of said receiver means and generating an intensity signal corresponding to said intensity of said ultrasonic noise;
and
judgement means, coupled to said intensity detector means, for determining a dry/wet condition of said road surface from said intensity signal output from said intensity detector means.

1 more element

A road surface condition detector for detecting a dry/wet condition of a road surface comprising:

receiver means mounted on a body of an automotive vehicle for receiving ultrasonic noise generated by a road wheel tire of said automotive vehicle, said receiver means exhibiting a directivity toward a contact surface between said road wheel tire and a road surface;
intensity detector means, coupled to said receiver means, for detecting an intensity of said ultrasonic noise from an output of said receiver means and generating an intensity signal corresponding to said intensity of said ultrasonic noise;
judgement means, coupled to said intensity detector means, for determining a dry/wet condition of said road surface from said intensity signal output from said intensity detector means;
transmitter means, mounted on said body of said automotive vehicle, exhibiting a directivity toward a contact surface between said road wheel tire and a road surface, for transmitting bursts of ultrasonic waves intermittently toward said road surface for reflection therefrom to said receiver means;
wherein said intensity detector means includes first extraction means, coupled to said receiver means, for extracting a first component corresponding to said ultrasonic noise from an output of said receiver means, said judgment means determining said road surface dry/wet condition from said first component extracted by said first extraction means.

2 more elements

Dependencies are inferred from the claim text.

Road surface condition detector for automotive vehicle

Life of this patent

Road surface condition detector for automotive vehicle

Life of this patent

Abstract

Claims15