Seat Belt Pretensioner with Staged Pulling for Side Collision Restraint
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Solution Overview
Problem
In far side collisions, existing occupant protection systems, such as airbags, fail to adequately restrain the upper body, leading to severe injuries as the occupant's head and body are shaken and collide with other occupants or interior members, due to insufficient restriction of movement in the vehicle width direction.
Innovation Solution
An occupant protection device incorporating a seat belt system with a locking tongue, shoulder-belt puller, lap-belt puller, and a control unit that detects side collisions, rapidly increasing the tensile force of the shoulder belt after initial restraint of the lap belt to prevent excessive movement and reduce chest injuries by transitioning the locking tongue state and pretensioner forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing occupant protection systems (airbags) are used in far side collisions, then the upper body is not adequately restrained, but the occupant's head and body collide with other occupants or interior members causing severe injuries
Solution Approach 1:
The seat belt system is divided into two independent pullers: a lap-belt puller for the lower body and a shoulder-belt puller for the upper body. This segmentation allows each puller to independently control the restraint force applied to different body regions, enabling the lap belt to restrain the hips first and the shoulder belt to subsequently restrain the upper body, preventing head and body collision with interior members
Solution Approach 2:
The control unit activates the lap-belt puller before the shoulder-belt puller in a two-stage sequence. The preliminary action of the lap-belt puller restrains the occupant's hips and lower body first, stabilizing the base of support. Subsequently, the shoulder-belt puller activates to restrain the upper body, preventing excessive forward and sideways movement that would cause collision with interior members
2Reliability
If the shoulder belt is pulled with high tensile force immediately in side collisions, then the upper body is restrained, but the chest may be injured due to excessive force
Solution Approach 1:
The control unit implements periodic action by activating the shoulder-belt puller in two distinct stages: a first pulling state with a predetermined preliminary pulling force, and a second pulling state with a larger pulling force. This staged approach allows the chest to gradually adapt to the restraint force, preventing immediate excessive force that would cause injury while still achieving effective upper body restraint
Solution Approach 2:
The lap-belt puller is activated in preliminary action before the shoulder-belt puller. By first restraining the hips and lower body, the occupant's center of gravity is stabilized, reducing the inertial forces acting on the chest. This preliminary stabilization allows the subsequent shoulder belt activation to apply force more safely without causing chest injury
3Ease of operation
If the locking tongue remains in unlock state during side collision, then the seat belt allows movement, but the occupant experiences excessive displacement in the vehicle width direction
Solution Approach 1:
The locking tongue is designed with dynamic state switching capability, transitioning from an unlock state during normal operation to a lock state during side collisions. This dynamic adaptation allows the system to maintain seat belt flexibility during everyday use while providing rigid movement restriction when collision is detected, ensuring both ease of operation and occupant protection reliability
Solution Approach 2:
The control unit activates the locking tongue to the lock state in preliminary action before the main restraint phase. By locking the tongue early in the collision sequence, the system ensures that the seat belt webbing cannot slip through the buckle, preventing any excessive displacement in the vehicle width direction while maintaining the flexibility benefits of the unlock state during normal operation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively restricts occupant movement in the vehicle width direction, reducing the risk of chest injuries by converting kinetic energy into rotational motion, thereby minimizing the distance of head and upper body displacement and preventing collisions with other occupants or interior members.
Implementation Method 1
a lap-belt puller that is capable of pulling the lap belt to apply a tensile force thereto
Implementation Method 2
a shoulder-belt puller that is capable of pulling the shoulder belt to apply a tensile force thereto
Implementation Method 3
The locking tongue is capable of switching between an unlock state in which the seat belt is allowed to move with the locking tongue being between the shoulder belt and the lap belt and a lock state in which movement thereof is restricted
Implementation Method 4
The side-collision detector is configured to detect a side collision or a precursor thereof
Data Source
AI summary
An occupant protection device including a seat belt that includes a shoulder belt and a lap belt, a locking tongue that is capable of switching between an unlock state and a lock state, a shoulder-belt puller that is capable of pulling the shoulder belt, a lap-belt puller that is capable of pulling the lap belt, a side-collision detector that detects a side collision or a precursor thereof, and a control unit that changes a state of the locking tongue into the lock state and a state of the lap-belt puller into a first pulling state in which the lap-belt puller pulls the lap belt and that subsequently changes a state of the shoulder-belt puller into a second pulling state in which the shoulder-belt puller pulls the shoulder belt when the side-collision detector detects the side collision that occurs opposite an occupant or the precursor thereof.