Webbing Take-up Device Switching Mechanism
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Solution Overview
Problem
Existing webbing take-up devices for vehicle seatbelts often cause operation noise and require excessive force during normal usage when switching between modes that allow or prevent deformation of the energy absorption member, affecting user sensation.
Innovation Solution
A webbing take-up device with a switching section and a switching restriction member that restricts movement between engaged and disengaged positions, allowing deformation only when necessary, reducing the need for force and noise by interlocking with the spool and rotation body, and using a guiding section to facilitate smooth switching without mechanical intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gas generator is used to switch between deformation and non-deformation modes of the energy absorption member, then mode switching is achieved, but costs increase
Solution Approach 1:
The patent replaces the gas generator-based switching mechanism with a purely mechanical switching section that utilizes the rotational movement of the spool itself to drive the switching action. The switching section includes a switching member that engages or disengages from the rotation body based on spool rotation, eliminating the need for gas generators and reducing device complexity while maintaining reliable mode switching.
Solution Approach 2:
The switching mechanism is designed to be self-actuating through the spool's own rotational movement. As the spool rotates during webbing pull-out or retraction, the switching section automatically transitions between engaged and disengaged states without requiring external power sources or control systems, thereby simplifying the overall device structure.
2Device complexity
If mechanical switching is performed between deformation and non-deformation modes during normal usage, then costs are reduced, but operation noise occurs and large force is required
Solution Approach 1:
The switching section is designed to transition smoothly between engaged and disengaged states through controlled rotational movement rather than abrupt mechanical engagement. The switching member gradually moves from one position to another, reducing impact forces and associated noise during mode transitions during normal usage.
3Device complexity
If mechanical switching is performed between deformation and non-deformation modes during normal usage, then costs are reduced, but large force is required during switching operation
Solution Approach 1:
The switching mechanism utilizes the existing rotational kinetic energy of the spool to drive the switching action. As the spool rotates during normal operation, this motion is transmitted to the switching section, which then transitions between modes using the available rotational force rather than requiring additional actuation force from the user.
Solution Approach 2:
The switching section acts as an intermediary mechanism that converts the spool's rotational movement into the engagement or disengagement of the energy absorption member. This intermediary mechanism amplifies the effect of the spool's rotation, enabling mode switching without requiring large additional forces from the user.
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
Enables seamless switching between deformation modes without user disturbance, reducing operational noise and force requirements, thus enhancing the user experience during normal usage of the seatbelt.
Implementation Method 1
a main torsion shaft and a sub torsion shaft that are disposed coaxially to the spool in the through hole in this order from the spool toward the leg plate, and a force limiter mechanism that restricts rotation of the spool in the pull-out direction
Data Source
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AI summary
In a webbing take-up device, configuration is made such that in a state in which a restriction wall of a cam gear is positioned at a lateral the side of a pin of a link configuring a switching section, the restriction wall abuts the pin when the link attempts to move. The restriction wall does not actively move the link regardless of the number of revolutions made by the cam gear. Operation noise of the link, a stopper pawl and a slide stopper accordingly does not occur during pull-out and take-up of webbing during normal usage, and a desirable user sensation is achieved in pull-out and take-up of the webbing during normal usage.