Vehicle seat load detection device

Abstract

A magnet is attached to springs of a sheet cushion. A connecting member is attached to side portions of a seat cushion frame. A magnetic sensor having a magnetic impedance element is fixed on the connecting member while being positioned right below the magnet. By seating of an occupant on the seat cushion, springs are downwardly bent to bring the magnet closer to the magnetic sensor and to thereby change the magnetic field of the magnet detected with the magnetic sensor. The load applied by an occupant to the seat cushion is detected on the basis of the change of the magnetic field.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a vehicle seat in an illustrative aspect of the present invention;

FIG. 2 is a perspective view of a state in which a cushioning material is removed from the vehicle seat shown in FIG. 1;

FIG. 3 is a sectional view taken along line A-A in FIG. 2;

FIG. 4 is an enlarged view of a portion shown in FIG. 3;

FIG. 5 is a diagram schematically showing the vehicle seat load detection device in the illustrative aspect of the present invention;

FIG. 6 is a sectional view showing a state in which the spring shown in FIG. 3 is bent;

FIG. 7 is a graph showing the relationship between the amount of bending of the springs and the output voltage from the magnetic sensor;

FIG. 8 is a diagram schematically showing an example of modification of the device in the illustrative aspect of the present invention; and

FIG. 9 is a diagram schematically showing an example of modification different from that shown in FIG. 8.

Claims

1. A vehicle seat load detection device for detecting a load applied to a vehicle seat having a non-bendable fixed member irrespective of the existence/nonexistence of the load and a flexible member displaceable relative to the fixed member by being bent under the applied load, through the amount of bending of the flexible member, the vehicle seat load detection device comprising: a magnetism generator which generates a magnetic field provided on one side of the fixed member and the flexible member, and a magnetic sensor having a magnetic impedance element provided on the other side to detect the magnetic field generated by the magnetism generator,wherein the flexible member is bent by an amount corresponding to the load applied to the vehicle seat to change the distance between the magnetism generator and the magnetic sensor and to thereby change the magnetic field generated by the magnetism generator, and the load applied to the vehicle seat is detected on the basis of the detected change of the magnetic field.

2. The vehicle seat load detection device according to claim 1, wherein the magnetic sensor is attached to the fixed member.

3. The vehicle seat load detection device according to claim 2, wherein the vehicle seat has a seat cushion to be sat on by an occupant; the flexible member comprises a plurality of spring members downwardly bendable by sitting on the seat cushion; the fixed member comprises a sheet frame for fixing the end portion of the spring members; a supporting member for supporting the magnetism generator is provided on the plurality of the spring members; a connecting member is stretched below the supporting member between two side portions of the seat frame facing each other so as to be opposed to the supporting member through a predetermined distance; the magnetic sensor is fixed on the connecting member; and the supporting member is downwardly bent together with the plurality of the spring members by seating on the vehicle seat to bring the magnetism generator closer to the magnetic sensor.