Seatbelt Retractor Guide Member Segmentation for Engagement Force
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing seatbelt retractors with pretensioners experience a reduction in engagement force during vehicle collisions due to the guide portion not being fixed, leading to inefficient rotation of the rotary member.
Innovation Solution
A seatbelt retractor design featuring a guide member with a tubular part and a hook portion that is fixed to the retractor frame, allowing the tubular part to move using reactive forces from rolling bodies, preventing a decrease in engagement between the rotary member and rolling bodies, ensuring efficient rotation during pretensioner operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the guide portion is made deformable to allow passage widening during pretensioner operation, then the balls can be pushed through the pipe without stopping, but the engagement amount between the ring gear and balls decreases leading to reduced force transmission
Solution Approach 1:
The guide member is segmented into a fixed portion (attached to retractor frame) and a movable portion (that can move in the radial direction). This segmentation allows the movable portion to widen the passage for ball movement while the fixed portion maintains the engagement amount between the ring gear and balls, resolving the contradiction between ease of operation and force transmission.
2Force
If the guide portion is fixed to prevent movement, then the engagement amount between ring gear and balls is maintained, but the passage cannot widen when balls are pushed back during energy absorption mechanism operation
Solution Approach 1:
The guide member is divided into fixed and movable portions. The fixed portion maintains engagement force while the movable portion provides passage widening capability when needed during energy absorption operations.
Solution Approach 2:
The guide member transitions from a completely fixed structure to a dynamic structure where the movable portion can change position radially. This allows the system to adapt between maintaining engagement force and widening passage based on operational requirements.
3Stability of the object's composition
If the guide member is completely fixed, then structural stability is improved, but the reactive force from rolling bodies cannot be utilized for efficient rotation
Solution Approach 1:
The guide member is segmented into fixed and movable portions. The fixed portion provides structural stability while the movable portion can move in response to rolling body forces, converting linear motion into rotational motion of the rotary member, thus improving productivity without sacrificing stability.
Solution Approach 2:
The movable portion of the guide member acts as an intermediary that translates the reactive force from rolling bodies into useful rotational motion. It mediates between the fixed structural framework and the rotary member, enabling efficient 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 design effectively maintains engagement between the rotary member and rolling bodies, ensuring efficient rotation and preventing reduction in transmitted force during pretensioner operation, enhancing the retraction efficiency of the seatbelt.
Implementation Method 1
a pretensioner that rotates the spindle in a retraction direction using a gas pressure generated when a gas generating medium is ignited
Data Source
AI summary
A pretensioner includes a gas generator, a pinion, a tube pipe, a piston ball, a plurality of balls, and a tube cover. The tube pipe includes a tubular part that is formed continuously from one end portion to the other end in order to receive the piston ball and the plurality of balls. A hook portion formed at the other end portion is angled toward the pinion. A tip end part of the hook portion is attached to at least one of a refractor frame and the tube cover. With this construction, a reduction in an engagement amount between the pinion and the balls during operation of the pretensioner can be prevented, and as a result, the pinion can be rotated efficiently.