Seat Belt Retractor Inertia Mass Preload for Rattle Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing self-locking belt retractors generate unwanted noise due to the relative movement of the inertia mass and control disc, which is caused by vibrations and tolerances in the pivot axis.
Innovation Solution
A pretensioning apparatus is introduced to preload the inertia mass parallel to the pivot axis, using a spring or deflectable elements to minimize relative movement and prevent rattling noises, with features like snap connections and locking webs to secure the inertia mass in place.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inertia mass has a certain mass to pivot when pull-out acceleration is exceeded, then the blocking function is achieved, but vibrations lead to unwanted noise being generated
Solution Approach 1:
The pretensioning apparatus applies a preliminary axial force to the inertia mass before operation, pre-compressing it against the control disc. This preliminary action eliminates axial play and prevents rattling noises during operation while maintaining the mass's ability to pivot for blocking function
Solution Approach 2:
The invention changes the force state of the inertia mass by applying a pretensioning force parallel to the pivot axis. This parameter change (from zero axial force to compressed state) eliminates noise-generating movements while preserving the pivoting capability needed for reliability
2Reliability
If the inertia mass is pivotably mounted on the control disc to control the blocking apparatus, then the safety function is achieved, but clearance due to tolerances causes unwanted noise
Solution Approach 1:
The pretensioning apparatus is installed and adjusted before final assembly, applying the necessary axial preload to eliminate clearance. This preliminary action ensures that when the assembly is put into service, the inertia mass is already in optimal contact with the control disc, preventing noise while maintaining safety function
Solution Approach 2:
The invention modifies the positional parameter of the inertia mass by applying axial compression. This changes the clearance state from having gaps (due to tolerances) to having continuous contact, eliminating noise sources while preserving the pivoting motion required for safety function
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 pretensioning apparatus effectively reduces noise by compensating for axial play and ensuring minimal movement of the inertia mass, thereby enhancing operational silence and ease of assembly.
Implementation Method 1
The control disc of the control disc device is spring-loaded in the belt pull-out direction of the belt shaft and rotates with the belt shaft below the predetermined pull-out acceleration of the safety belt
Implementation Method 2
An inertia mass is pivotably mounted on the control disc, which pivots when the predetermined pull-out acceleration of the safety belt is exceeded and thereby engages in a frame-mounted toothing of the belt retractor
Implementation Method 3
a control disc device which is mounted on the belt shaft and which is particularly spring-biased in the direction of extension of the safety belt
Data Source
AI summary
A self-locking belt retractor comprising a belt shaft which is rotatably mounted in a frame, wherein a safety belt can be wound up said belt shaft, a blocking device which blocks the belt shaft if a predetermined feed-out acceleration of the safety belt in the feed-out direction of the safety belt is exceeded, and comprising a control disc device mounted on the belt shaft, the control disc device comprising a control disc and an inert mass which is mounted on the control disc so as to be pivotable about a pivot axis.