Vehicle Sensor Assembly Angled Planar Surface Vibration Damping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vehicle occupant protection devices face issues with unwanted or nuisance locking of seat belt retractors due to vehicle vibrations, which can lead to false activation and reduced effectiveness during intended protection scenarios.
Innovation Solution
A vehicle sensitive sensor assembly with an inertia locking mechanism, featuring a movable inertia member and planar surfaces, prevents rotation of the spool in the belt withdrawal direction only during predetermined conditions like sudden deceleration or tilt, using a sensor lever element and support element with angled planar surfaces to dampen vibrations and ensure proper activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a vehicle sensitive sensor assembly is used to activate the occupant protection device, then the protection device can be activated during critical vehicle conditions, but the sensor may cause unwanted or nuisance locking of the spool in response to vehicle vibrations
Solution Approach 1:
The planar surface is positioned at a specific angle (e.g., 30-60 degrees) relative to the vertical axis to create directional sensitivity. This local geometric property allows the inertia member to respond differently to vibrations versus critical deceleration events, enabling the sensor to distinguish between harmful vibrations and legitimate activation conditions.
Solution Approach 2:
The angle of the planar surface relative to the vertical axis is optimized to change the sensitivity threshold of the sensor. By adjusting this geometric parameter, the sensor can be tuned to ignore low-intensity vibrations while remaining sensitive to high-intensity deceleration or tilt events that require activation.
2Reliability
If the inertia member is made sensitive to vehicle conditions, then it can prevent spool rotation during deceleration and tilt, but it may also lock the spool during normal vehicle vibrations
Solution Approach 1:
The planar surface creates an asymmetric response characteristic where the inertia member can move freely in one direction during normal vibrations but is constrained in the opposite direction during critical events. This asymmetric geometry enables the sensor to differentiate between normal operational vibrations and critical conditions requiring activation.
Solution Approach 2:
The combination of the spherical cavity and the angled planar surface creates a specific geometric interaction that allows controlled movement. The curvature of the spherical cavity provides a stable resting position for the inertia member, while the planar surface at an angle creates a threshold effect that prevents false activation during minor vibrations.
3Adaptability or versatility
If the support has a spherical cavity for the inertia member, then the inertia member can move freely, but the sensor causes nuisance locking due to vibrations
Solution Approach 1:
The planar surface is positioned at a specific angle (e.g., 30-60 degrees) relative to the vertical axis to create directional sensitivity. This local geometric property allows the inertia member to respond differently to vibrations versus critical deceleration events, enabling the sensor to distinguish between harmful vibrations and legitimate activation conditions.
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
The solution effectively prevents false locking during normal vehicle conditions like vibrations while ensuring timely activation during critical events like deceleration or tilt, enhancing the reliability and effectiveness of the occupant protection device.
Implementation Method 1
an inertia member movable relative to a support from an unactuated position to an actuated position in response to at least one sensed vehicle condition
Implementation Method 2
at least one of the element and the inertia member has at least one planar surface that extends at an angle relative to the vertical axis. The inertia member and element are movable relative to one another along the at least one planar surface
Data Source
AI summary
A vehicle occupant protection device (10) for helping to protect an occupant of a seat of a vehicle includes an inertia member (66) that engages an element (54). The inertia member (66) is movable relative to the element (54) from an unactuated position to an actuated position in response to at least one sensed vehicle condition for activating the occupant protection device (10). A vertical axis (83) extends through the center of mass of the inertia member (66) when the inertia member (66) is in the unactuated position. At least one of the element (54) and the inertia member (66) has at least one planar surface (80) that extends at an angle relative to the vertical axis (54). The inertia member (66) and element (54) are movable relative to one another along the at least one planar surface (80) to place the inertia member (66) in the actuated position to activate the occupant protection device.