Seat-belt pretensioner with slip-based tension control
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Solution Overview
Problem
Existing seat-belt pretensioner systems lack the ability to dynamically adjust tension based on real-time vehicle slip conditions, potentially failing to provide optimal protection during varying accident scenarios.
Innovation Solution
A seat-belt pretensioner arrangement with a control system that processes signals from multiple sensors to generate slip functions indicative of vehicle handling conditions, such as over-steer/under-steer, body slip, evasive maneuvering, and high-speed cornering, and adjusts tension accordingly using a discriminator and comparator to select and apply appropriate tension levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a pyrotechnic charge is used to actuate the pretensioner, then the pretensioner can generate high tension quickly, but the system lacks the ability to dynamically adjust tension levels based on vehicle slip conditions
Solution Approach 1:
The patent applies dynamics by enabling the pretensioner system to transition from a static, fixed-tension design to a dynamic, adjustable-tension system. The control system continuously monitors vehicle slip conditions and real-time adjusts the pretensioner output to match the actual accident severity and vehicle handling characteristics, allowing the seat-belt tension to adapt dynamically rather than applying a fixed high force in all scenarios
Solution Approach 2:
The patent implements parameter changes by varying the pretensioner output parameters (tension magnitude and application timing) based on processed sensor data. The control system modifies operational parameters such as the amount of reel rotation, piston displacement, or wire spooling based on slip function values, enabling continuous adjustment of tension levels to optimize protection while minimizing discomfort
2Reliability
If high seat-belt tension is applied in all accident situations, then optimal protection is provided, but excessive discomfort and potential injury may occur in less severe situations
Solution Approach 1:
The patent applies partial action by providing only the necessary amount of pretensioner force required for each specific accident scenario. Rather than applying maximum tension in all cases, the control system calculates the appropriate tension level based on slip conditions and applies only that amount, avoiding excessive force when the accident severity is low while ensuring sufficient force when severity is high
Solution Approach 2:
The patent implements feedback by continuously monitoring vehicle dynamics parameters (longitudinal velocity, lateral acceleration, angular velocity, steering angle) and using this information to adjust pretensioner output. The control system processes sensor signals to determine actual accident severity and feeds this information back to the pretensioner actuator, creating a closed-loop system that adjusts tension in real-time based on actual conditions rather than assuming worst-case scenarios
3Measurement precision
If multiple sensors are used to detect vehicle slip conditions, then accurate tension adjustment is achieved, but the device complexity increases
Solution Approach 1:
The patent applies universality by designing the control system to process multiple sensor inputs (longitudinal velocity, lateral acceleration, angular velocity, steering angle) through a unified slip function calculation framework. Rather than requiring separate processing paths for each sensor type, the system uses a general-purpose microprocessor or microcontroller that can handle all sensor data through common algorithms, reducing overall system complexity despite the multiple sensors employed
Data Source
AI summary
A seat-belt pretensioner arrangement includes a pretensioner configured to apply at least two tension levels to a seat-belt and a control system to control the pretensioner. A control system is configured to provide at least one vehicle slip function which is derived from at least one sensed parameter relating to the current or expected dynamic situation of the vehicle. The control system is configured to select the tension level to be applied to the seat-belt by the pretensioner in response to the value of the slip function provided by the control system.