Upper Backrest Linkage to Cut Actuator Load in Vehicle Seats
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Solution Overview
Problem
Existing vehicle seat backrest adjustment devices require high forces during rotation, leading to motor overload and premature wear, and experience excessive loading and force transmission during collisions, complicating integration and assembly.
Innovation Solution
The upper backrest adjustment device features a kinematic system with a support member pivotably mounted on a backrest frame, connected via articulated rods and an actuator that reduces force variation and transmission, allowing for reduced motor dimensions and enhanced structural reinforcement, while maintaining comfort and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional upper backrest adjustment device is used, then the support member can be adjusted between retracted and advanced positions, but high forces are required during rotation causing motor overload and premature wear
Solution Approach 1:
The backrest adjustment device is segmented into multiple independent components: support member, intermediate part, connecting rod, and actuator. Each component has a specific function and can move independently through pivotable articulations about different transverse axes, distributing the mechanical load across multiple joints rather than concentrating force on the actuator alone.
Solution Approach 2:
An intermediate part is introduced as a mediator between the support member and the connecting rod. This intermediate part pivotably articulates relative to both the support member and the connecting rod, acting as a force-distributing intermediary that reduces the peak force transmission to the actuator during support member rotation.
2Reliability
If the actuator is designed to handle high forces, then the support member can be adjusted reliably, but the motor dimensions increase and the device becomes more complex
Solution Approach 1:
The kinematic chain is segmented into multiple simple pivotable joints rather than requiring a single complex high-force actuator. Each segment (support member, intermediate part, connecting rod) connects through simple pivot articulations, reducing individual component complexity while maintaining system reliability.
Solution Approach 2:
The device uses a dynamic kinematic chain where multiple parts move relative to each other through pivotable articulations. This dynamic distribution of motion and force allows the system to adapt force requirements during operation, avoiding the need for an oversized static actuator design.
3Object-affected harmful factors
If the support member is in the retracted position during a collision, then occupant safety is compromised, but the force transmitted to the actuator and kinematics increases excessively
Solution Approach 1:
The kinematic chain converts the harmful collision force into beneficial operational characteristics. The pivotable articulations and intermediate part create a kinematic mechanism that naturally reduces force transmission to the actuator during collision, while the support member's ability to rotate provides both safety functionality and force reduction.
Solution Approach 2:
The intermediate part serves as a mediator that reduces force transmission during collision events. By pivotably articulating between the support member and connecting rod, it acts as a force-dampening intermediary that protects the actuator and kinematic components from excessive loading during safety-critical collision scenarios.
Data Source
AI summary
The present disclosure relates to a backrest for a vehicle seat comprising a backrest frame and a upper backrest adjustment device comprising a support member intended to receive, bearing against a front face, the upper back of an occupant of the seat, pivotably mounted on the backrest frame; at least one first connecting rod pivotably articulated relative to the backrest frame; an intermediate part between the support member and the first connecting rod, pivotably articulated relative to the support member and relative to the first connecting rod, an actuator for adjusting the position of the support member between a retracted position and an advanced position, the actuator comprising a pivotably articulated connecting part relative to the intermediate part.