US 5,739,757 A · Vehicle passenger weight sensor

Abstract

A vehicle safety system having crash detection circuitry and an airbag adjacent a vehicle seat further includes a system for determining the weight of a passenger on the vehicle seat. If the detected weight of the passenger does not exceed a predetermined weight threshold, the airbag is disabled. A forward sensor and a rear sensor are mounted in a vehicle seat adjacent a ferromagnetic structure element in the seat. The sensors measure strain on the ferromagnetic element, which is proportional to weight on the vehicle seat. A comparison of the measurements of the two sensors also provides an indication of the position of the passenger on the vehicle seat, such that the airbag may be disabled if the passenger is sitting too close to the airbag. Each of the sensors preferably comprises an electromagnet generating an oscillating magnetic field of a known frequency and a coil. Strain on the ferromagnetic element alters the magnetic field and such strain is detected by the coil. The detected change in the magnetic field is proportional to the weight of the passenger.

Claims15

Dependent claims

A system for measuring a weight upon a seating surface within a motor vehicle, said system comprising:

(a) a ferromagnetic element mechanically coupled to the seating surface such that strain is induced in said ferromagnetic element responsive to the weight thereon;
and
(b) a first sensor comprising (i) a magnet generating a magnetic field and (ii) an inductor, said magnet and inductor mounted on the vehicle adjacent said ferromagnetic element, said magnetic field altered by said strain in said ferromagnetic element, said inductor generating a signal based upon the alteration in said magnetic field.

A vehicle safety system comprising:

(a) a vehicle seat having a seating surface;
(b) a vehicle safety device positioned operatively with respect to said vehicle seat;
(c) crash detection circuitry generating a trigger upon detection of a sufficient impact to said vehicle;
(d) an actuator for actuating said vehicle safety device;
(e) a ferromagnetic element mechanically coupled to the seating surface such that strain is induced in said ferromagnetic element by weight on said seating surface;
and
(f) a first sensor mounted on the vehicle adjacent said ferromagnetic element and generating a magnetic field, said first sensor comprising a magnet and a first coil mounted on the vehicle adjacent said ferromagnetic element, said magnetic field generating an electromotive force voltage in said first coil, said electromotive force voltage being altered by an alteration in said magnetic field, said strain in said ferromagnetic element altering said magnetic field, said first sensor generating a signal based upon said alteration in said magnetic field, said actuator actuating said vehicle safety device based upon said signal from said first sensor and said trigger by said crash detection circuitry.

4 more elements

Dependencies are inferred from the claim text.

Vehicle passenger weight sensor

Life of this patent

Vehicle passenger weight sensor

Life of this patent

Abstract

Claims15