Webbing Take-Up Device Mode Switching Mechanism
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Solution Overview
Problem
Existing webbing take-up devices for seatbelts have complex structures for switching between modes of torsional deformation in energy absorbing members, requiring multiple components and complicating the mode-switching process.
Innovation Solution
A webbing take-up device with a spool, lock bases, energy absorbing members, lock pawls, and a switching unit that allows for simple switching between modes of torsional deformation in the first and second energy absorbing members by controlling the engagement and rotation of the lock ring, using a connecting member to interlock the lock pawls and break connections to achieve deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a switching device with locking element and spindle ring is used to switch between modes, then mode switching capability is achieved, but device complexity increases due to multiple required members
Solution Approach 1:
The patent combines the locking element and spindle ring into a single integrated locking mechanism that rotates between locked and unlocked positions. This merging of previously separate components into one unified structure directly reduces device complexity while maintaining the mode switching capability between single torsion bar and dual torsion bar configurations.
Solution Approach 2:
The locking mechanism serves multiple functions: it locks the spool in the retracted position, enables mode switching between single and dual torsion bar engagement, and controls the pretensioner activation. This multi-functionality eliminates the need for separate switching devices and additional members, thereby reducing overall device complexity.
2Adaptability or versatility
If a switching device with torque tube and locking element is implemented, then mode switching is achieved, but the number of required members increases
Solution Approach 1:
The patent merges the torque tube function into the spool structure itself, where the spool acts as the rotating element that engages or disengages the torsion bars. This eliminates the need for a separate torque tube member while maintaining the mode switching function between single and dual torsion bar configurations.
Solution Approach 2:
The spool serves multiple functions: it winds the webbing, acts as the torque transmission element, and functions as the switching mechanism by rotating to engage or disengage the torsion bars. This multi-functionality reduces the total number of members required in the device.
3Adaptability or versatility
If multiple members such as locking element, spindle ring, and torque tube are used, then mode switching capability is achieved, but ease of manufacture decreases
Solution Approach 1:
By combining multiple members into integrated structures (locking mechanism, spool as torque element), the patent reduces the number of discrete parts that need to be manufactured and assembled. This simplification directly improves ease of manufacture while maintaining full mode switching capability between single and dual torsion bar configurations.
Solution Approach 2:
The locking mechanism and spool perform multiple functions simultaneously, eliminating the need for separate dedicated components for each function. This reduction in component count simplifies manufacturing processes and assembly operations.
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
This design simplifies the structure for switching between modes of deformation, allowing for efficient energy absorption and passenger inertial movement by selectively engaging and disengaging the lock ring to control the deformation of the energy absorbing members.
Implementation Method 1
a first energy absorbing member that is connected at an inner side of the spool, in a state in which relative rotation of the first energy absorbing member with respect to the spool is restricted, and that is connected at the one end side of the spool in the axial direction, in a state in which relative rotation of the first energy absorbing member with respect to the first lock base is restricted
Data Source
AI summary
In a webbing take-up device, a structure for interlocking a second lock pawl with a first lock pawl is only a shaft. It also suffices for switching between restricting of rotation of a lock ring and cancelling of the restricting to be carried out merely by moving a piston by gas pressure generated at a gas generator. In this way, by a simple structure, it is possible to switch between a mode, in which torsional deformation is brought about at a sub torsion main body of a sub torsion shaft, and a mode, in which torsional deformation is not brought about at the sub torsion main body of the sub torsion shaft.