Webbing Take-Up Device Axial Clutch Restriction
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Solution Overview
Problem
Existing webbing take-up devices face issues with the friction spring moving axially on a cylindrical gear, potentially disrupting rotation force transmission, leading to instability in overload release mechanisms.
Innovation Solution
A webbing take-up device is designed with a restriction section along the axial direction of a second gear to prevent movement of the clutch member towards the first gear, utilizing a rotor with a circular cylinder portion and a corner portion to securely wind the clutch member, ensuring it remains on the rotor side of the maximum external diameter position, thus preventing further movement towards the first gear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the friction spring is attached to the cylindrical portion of the small diameter gear, then the overload release mechanism can function, but the friction spring may move axially along the cylindrical portion causing instability
Solution Approach 1:
A restriction section is introduced as an intermediary component between the clutch member and the first gear. This restriction section prevents axial movement of the clutch member along the cylindrical portion, thereby stabilizing the overload release mechanism while maintaining its functionality.
Solution Approach 2:
The solution addresses the axial movement problem by adding a dimensional constraint through the restriction section that extends in the axial direction. This creates a physical barrier that limits the clutch member's movement to a specific axial range, preventing it from moving along the cylindrical portion.
2Device complexity
If the clutch member is allowed to move freely axially, then the device structure remains simple, but rotation force transmission becomes unstable
Solution Approach 1:
The restriction section serves as a simple intermediary structure that adds minimal complexity to the device. It effectively constrains the clutch member's axial movement without requiring complex mechanisms, thereby maintaining rotation force transmission stability with minimal structural addition.
3Reliability
If the restriction section is added to prevent axial movement, then axial movement of clutch member is restricted, but the device complexity increases
Solution Approach 1:
The restriction section is designed to be integrated with the existing gear structure. By merging the restriction function into the existing components rather than adding completely separate parts, the increase in device complexity is minimized while still achieving the goal of restricting axial movement.
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 configuration effectively restricts axial movement of the clutch member, maintaining secure winding on the rotor and preventing slipping torque variations, enhancing the stability and efficiency of rotation force transmission in the device.
Implementation Method 1
a restriction section that is provided, along an axial direction of the second gear, between the first gear and the clutch member, and that restricts movement of the clutch member toward the first gear side
Implementation Method 2
a clutch member that is provided at the first gear and transmits rotation between the second gear and the first gear
Data Source
AI summary
A webbing take-up device is obtained capable of restricting movement of a clutch member in the axial direction of a second gear. In the webbing take-up device, a movement prevention portion is formed, on a rotor side, at an intermediate bottom portion of a large gear portion, and a clutch spring attached to the rotor abuts the movement prevention portion, thereby preventing any movement of the clutch spring further to the intermediate bottom portion side. Movement of the clutch spring in the axial direction of the rotor can accordingly be suppressed, enabling movement of the clutch spring in the axial direction of the rotor to be restricted.