Safety Belt Retractor Integrating Pre-Tensioning and Force-Limiting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vehicle safety belt retractors require significant axial structural space due to separate pre-tensioning and force-limiting devices, leading to increased weight and complexity, and do not achieve complete decoupling from the driving element.
Innovation Solution
A compact safety belt retractor design integrating a pre-tensioning, force-limiting, and decoupling device on a single end segment, featuring a safety belt reel with a driving element, sleeve, and energy absorbing disc, utilizing helical surfaces and projections for efficient axial force transfer and decoupling, and a pyrotechnic driving unit for enhanced functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate pre-tensioning device and force-limiting device are arranged on two ends of the safety belt reel, then the pre-tensioning function and force-limiting function are achieved, but the axial structural space requirement increases significantly
Solution Approach 1:
The patent combines the pre-tensioning device and force-limiting device into a single integrated structure on one end of the safety belt reel. The driving element incorporates both a pre-tensioning projection with helical surface and a force-limiting projection, eliminating the need for separate devices on opposite ends of the reel. This merging reduces the axial space requirement while maintaining both safety functions.
Solution Approach 2:
The driving element serves multiple functions simultaneously: it provides pre-tensioning through the helical surface interaction, force-limiting through the breakable projection design, and decoupling capability through the integrated projection structures. This multi-functionality allows a single component to replace what would traditionally require multiple separate devices, reducing overall system complexity and axial dimension.
2Reliability
If separate pre-tensioning device and force-limiting device are used, then both functions are achieved, but the device complexity and number of parts increase
Solution Approach 1:
The patent merges the pre-tensioning device and force-limiting device into a single driving element with integrated projections. This consolidation reduces the number of discrete parts while maintaining both safety functions, thereby reducing device complexity and assembly requirements.
Solution Approach 2:
The driving element is designed as a multi-functional component that performs pre-tensioning, force-limiting, and decoupling operations. By making this single component universal in its functionality, the patent eliminates the need for multiple specialized parts, simplifying the overall device structure.
3Reliability
If axial space is reserved for safety belt reel movement against housing wall, then decoupling function is enabled, but the axial structural space requirement increases
Solution Approach 1:
The driving element is pre-loaded against the safety belt reel through the integrated projection structures during normal operation. In the event of a collision, the force-limiting projection breaks and the pre-tensioning projection rotates, enabling automatic decoupling without requiring additional axial movement space. The decoupling action is initiated by the pre-positioned projection interactions rather than requiring post-failure axial travel.
Solution Approach 2:
The patent transitions the decoupling mechanism from axial movement to rotational movement. The pre-tensioning projection's helical surface causes the driving element to rotate relative to the safety belt reel during decoupling, rather than requiring axial displacement. This dimensional change from linear to rotational motion eliminates the need for reserved axial space while maintaining the decoupling function.
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 solution achieves a compact axial structure, reduces the number of parts, enables complete decoupling, and provides effective pre-tensioning and force-limiting functions, enhancing passenger safety while minimizing structural space and weight.
Implementation Method 1
an energy absorbing disc which is capable of being plastically deformed when squeezed by the axial outer end of the sleeve and/or the axial outer end of the driving element
Implementation Method 2
A first helical surface is arranged on an end, facing a safety belt retracting direction, of the first recess. A second surface acting together with the first helical surface... The driving element is capable of transferring an axial force to the sleeve
Data Source
AI summary
A safety belt retractor, a vehicle safety belt with the safety belt retractor and a vehicle with the vehicle safety belt are provided. The safety belt retractor is provided, on an end segment thereof, with a pre-tensioning, force-limiting and decoupling device that comprises a safety belt reel (1), a driving element (2), a sleeve (3) and an energy absorbing disc (4). The safety belt reel (1) is provided with a first recess (10) and a second recess. A first helical surface (9) is arranged in the first recess (10), and the driving element (2) is provided with a first projection (21) having a second helical surface acting together with the first helical surface (9). The sleeve (3) is provided with a second projection (31) mounted in the second recess. Under a predetermined load, the second projection (31) is cut off, such that the energy absorbing disc (4) is plastically deformed due to squeezing. The safety belt retractor achieves on the same end segment, the pre-tensioning, force-limiting and decoupling functions as well as a compact structure.