Vehicle Seat Load Sensor Isolation via Sliding Bridging Member
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Solution Overview
Problem
Conventional passenger weight measurement devices in vehicles face inaccuracies due to the transmission of inertia forces during a front collision, leading to the 'submarine phenomenon' where the passenger is pushed under the waist belt, and this affects the accuracy of weight measurement.
Innovation Solution
A vehicle seat design featuring a load sensor under the cushion with a bridging member between mounting units that is slidable in the left-and-right direction, preventing the transmission of loads to the sensor and holding the passenger's buttocks in place during collisions, ensuring accurate weight measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the supporting member is disposed at a position lower than the seating surface to prevent the submarine phenomenon, then the passenger safety is improved, but the weight measurement accuracy deteriorates because inertia forces are transmitted to the load sensor through the supporting member and cushion frame
Solution Approach 1:
The supporting member is divided into two functional parts: a first supporting portion that contacts the passenger's buttocks for safety, and a second supporting portion that is slidable relative to the cushion frame to prevent inertia force transmission. This segmentation allows each part to perform its specific function without interfering with the other.
Solution Approach 2:
The second supporting portion is designed to be slidable relative to the cushion frame along a sliding surface, transforming a static structure into a dynamic one. During normal operation, it provides support; during collision, it slides to isolate the load sensor from inertia forces, thus maintaining measurement accuracy while preserving safety functionality.
2Reliability
If the bridging member is made fixed to prevent submarine phenomenon, then passenger holding capability is improved, but measurement accuracy deteriorates due to load transmission in left-and-right direction
Solution Approach 1:
The bridging member is designed with sliding capability relative to the mounting units, allowing it to move in the left-and-right direction when subjected to lateral loads during collision. This dynamic behavior prevents load transmission to the load sensor while maintaining the structural integrity needed for passenger holding capability.
Solution Approach 2:
The sliding mechanism acts as an intermediary between the bridging member and the mounting units, allowing relative motion that decouples the lateral load path from the load sensor. This intermediary mechanism enables the system to simultaneously achieve passenger holding and measurement accuracy.
Data Source
AI summary
The submarine phenomenon can be prevented and the accuracy of a passenger's weight measurement is improved.A vehicle seat 1 comprises a pair of fixed lower rails 3 fixed on the floor of a passenger compartment, a pair of movable upper rails 4 which are engaged with the fixed lower rails 3 so as to be slidable in a front-and-rear direction with respect to each of the fixed lower rails 3, a sub frame 110 which is disposed at an upper side of the movable upper rails 4, load sensors 50, 60, 70, and 80 which lie between the sub frame 110 and the movable upper rails 4, brackets 8 and 9 which are disposed so as to erect them on each of the movable upper rails 4, and a submarine pipe 11 which is crossed between the brackets 8 and 9. The submarine pipe 11 is disposed to be slidable in a left-and-right direction with respect to the right bracket 9.