Patent ID: 9400206
Filing Date: 2016-07-26
CPC Classification: B60N,B60R,G01G,G01L

Claim Text:
1. A weight detection sensor for a vehicle seat apparatus disposed in a fixing unit that fixes a seat side fixing member which fixes a vehicle seat to a floor side fixed member which is fixed to a vehicle floor at four front, back, left, and right sides of the vehicle seat and measuring a load of a passenger sitting in the vehicle seat, comprising: a strain body that is fixed to both end portions of a mounting surface formed on one of the floor side fixed member and the seat side fixing member and arranged in the fixing unit on a front side and a back side of the vehicle seat at a predetermined distance from the mounting surface, the strain body extending in a front-back direction of the vehicle seat; a connection member that is fixed to a central portion of the strain body in a vertical direction and is fixed to the other one of the floor side fixed member and the seat side fixing member; a strain detection element unit that includes a first strain detection element and a third strain detection element arranged on opposite sides across a front-back direction center line of the strain body at positions where a compressive strain is generated on an outer surface of the strain body between a first end portion and the central portion of the strain body when a weight of the passenger is applied, and a second strain detection element and a fourth strain detection element arranged on opposite sides across the front-back direction center line of the strain body at positions where a tensile strain is generated on the outer surface of the strain body between the first end portion and the central portion of the strain body when the weight of the passenger is applied, the front-back direction center line of the strain body extending between the end portions of the mounting surface; and a Wheatstone bridge circuit where the first strain detection element and the third strain detection element are arranged on sides facing each other and the second strain detection element and the fourth strain detection element are arranged on sides facing each other, each of the strain detection elements being a variable resistor, wherein the strain detection element units are arranged in a pair in at least a front and a back or a left and a right of the vehicle seat and the first end portions forming the pair are arranged at symmetrical positions in the directions forming the pair.