Webbing Take-up Device Sub-clutch Mechanism
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Solution Overview
Problem
Existing webbing take-up devices suffer from motor operation loss due to unnecessary rotation of the clutch when the motor rotates in one direction, leading to inertia and inefficient energy use.
Innovation Solution
A webbing take-up device is designed with a sub-clutch mechanism that includes a coil spring to selectively transmit or block rotation force between the first rotating body and the clutch, preventing clutch rotation when no force transmission is needed, thereby conserving energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the clutch is rotated by the motor irrespective of rotation direction, then the clutch can transmit rotation force to the spool when needed, but unnecessary rotation occurs when the motor rotates toward the another side, causing inertia and motor operation loss
Solution Approach 1:
The sub clutch is configured to dynamically change its force transmission state based on the rotation direction of the first rotating body. When the first rotating body rotates toward the another side, the sub clutch transmits rotation force to the clutch; when it rotates toward the one side, the sub clutch blocks force transmission. This dynamic adaptation eliminates unnecessary clutch rotation and associated energy loss while maintaining reliable force transmission when needed.
Solution Approach 2:
The sub clutch acts as an intermediary component between the first rotating body and the clutch. It selectively mediates the transmission of rotation force based on rotation direction, allowing force transmission in one direction while blocking it in the other direction. This intermediary function prevents direct coupling between the motor and clutch when force transmission is not required, reducing motor operation loss.
2Loss of energy
If the sub clutch is added to selectively transmit or block rotation force, then energy efficiency is improved by preventing unnecessary clutch rotation, but the device complexity increases due to additional components
Solution Approach 1:
The sub clutch mechanism is integrated into the existing clutch assembly, merging the force transmission control function directly into the clutch structure. The sub clutch and clutch share the same rotational axis and are positioned adjacently, allowing them to work together as a unified force transmission system. This merging approach adds minimal structural complexity while achieving the energy efficiency benefit of selective force transmission.
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 sub-clutch mechanism effectively suppresses clutch rotation when no force transmission is required, enhancing energy efficiency and reducing motor operation loss by ensuring that rotation is only transmitted when necessary.
Implementation Method 1
the sub clutch being configured by a sub clutch spring that includes a coil portion wound in a ring shape... the rotation force of the first rotating body is transmitted to the clutch by the coil portion making pressing contact with the first rotating body
Data Source
AI summary
A webbing take-up device includes a spool that takes up webbing worn by an occupant, an input gear that is rotated by rotation force being transmitted, a spool gear that rotates the spool by being rotated, and a second clutch that is provided between the input gear and the spool gear, and that transmits rotation force of the input gear to the spool gear by being rotated by the input gear. The webbing take-up device further includes a sub clutch spring that is provided between the input gear and the second clutch, that transmits rotation force of the input gear to the second clutch when the input gear is rotated toward one side, and that shuts off transmission of rotation force of the input gear to the second clutch when the input gear is rotated toward another side.