Belt Retractor Two-Part Drive Wheel Assembly
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Solution Overview
Problem
Existing motor vehicle seat belt retractors face challenges in ease of assembly and space efficiency, particularly due to complex component interactions and additional components required for fixation.
Innovation Solution
A two-part pretensioner drive wheel configuration, comprising a profile head and a push-on ring with dome-shaped partial receiving socket segments, along with a force-limiting torsion bar, ensures secure vehicle fixation and simplified assembly by eliminating the need for additional components and providing a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a one-part pretensioner drive wheel is used with a special bearing ring, then the shaft body can be securely fixed, but the assembly becomes complex with many parts pushed onto the profile head
Solution Approach 1:
The drive wheel is divided into two separate parts: the profile head and a push-on ring. The push-on ring is inserted onto the profile head and secured through plastic deformation of an annular projection, eliminating the need for additional bearing rings while maintaining secure fixation of the shaft body.
2Reliability
If additional components are used for fixing the pretensioner drive on the profile head, then secure fixation is achieved, but the space requirement increases
Solution Approach 1:
The fixation function is merged into the push-on ring itself, which combines both the mounting function and the securing function. The annular projection on the profile head serves dual purposes: guiding the push-on ring during assembly and providing the deformation zone for secure fixation, eliminating the need for separate fixation components.
3Ease of manufacture
If a two-part configuration is used with push-on ring, then assembly is simplified and space is reduced, but additional fixation mechanism is needed
Solution Approach 1:
The push-on ring performs self-service by simultaneously serving as the mounting component and its own fixation mechanism. The annular projection is designed to be plastically deformed during assembly to lock the push-on ring in place, eliminating the need for separate fixation mechanisms while maintaining ease of assembly.
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 enables easy assembly, reduces space requirements, and ensures secure locking of the seatbelt by allowing the belt pretensioner to wind the belt webbing effectively while limiting force on the occupant during acceleration.
Implementation Method 1
a force-limiting torsion bar is additionally provided between the profile head and the shaft body. If the torsion bar thereby limits the force effect of the seatbelt acting on the occupant
Implementation Method 2
one end of the profile head can be especially caulked or crimped, so that the push-on ring can no longer be detached from the profile head without destroying it due to the plastic deformation of the profile head
Data Source
AI summary
A belt retractor having a belt shaft having a shaft body, a profile head and a torsion bar, wherein the torsion bar arranged in the shaft body is connected on one end to the shaft body and on a second end to the profile head, and the profile head can be securely attached to the vehicle, and having a belt pretensioner, wherein a pretensioner drive wheel of the belt pretensioner is directly connected in a rotationally fixed manner to the profile head of the belt shaft, and mass bodies can be engaged with the pretensioner drive wheel so as to transmit force to drive the belt shaft in winding direction. The pretensioner drive wheel (16) is configured by means of two parts, the profile head (1) of the belt shaft and a push-on ring (2) that is pushed onto the profile head (1) and is positively and non-positively connected thereto, wherein respectively mutually opposite dome-shaped partial receiving socket segments (3), which form together receiving sockets for the mass bodies, are formed on the profile head (1) and on the push-on ring (2).