Seat Belt Retractor Coupling for Controlled Tensioner Engagement
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Solution Overview
Problem
Existing belt retractors face challenges in efficiently transmitting drive movement from the drive wheel to the belt reel, particularly due to unintended rotational connections that hinder normal use and interfere with the operation of reversible and irreversible belt tensioners.
Innovation Solution
A belt retractor design featuring a coupling pawl with an enlarged catch tooth and a force transmission surface on the drive wheel, aligned to synchronize engagement with the belt reel toothing, reduces bearing forces and ensures direct torque transmission without unintended connections, using control contours for reversible and irreversible tensioner activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a coupling mechanism is provided to connect the drive wheel to the belt reel, then drive force transmission is enabled, but unintended rotational connections occur that hinder normal use and interfere with tensioner operation
Solution Approach 1:
The coupling pawl is designed with a control element that dynamically changes the engagement state based on operational conditions. During normal use, the coupling pawl remains disengaged allowing free rotation of the belt reel. Upon detection of specific conditions (such as acceleration changes), the control element automatically engages or disengages the coupling, enabling power transmission only when needed without interfering with normal operation.
Solution Approach 2:
The coupling pawl acts as an intermediary component between the drive wheel and the belt reel. It selectively transmits torque from the drive wheel to the belt reel only when engaged, while allowing the belt reel to rotate freely when disengaged. This intermediary mechanism resolves the contradiction by providing conditional power transmission that does not permanently constrain the system.
2Power
If the coupling pawl engages in the toothing during normal operation, then drive transmission is maintained, but interference with reversible and irreversible tensioner activation occurs
Solution Approach 1:
The coupling mechanism dynamically adjusts its engagement state in response to different operational modes. During normal operation, the coupling pawl engages to transmit drive force. When tensioner activation is detected (through control elements sensing acceleration or other parameters), the coupling automatically disengages to allow the tensioner to operate independently without interference, then re-engages after tensioning is complete.
3Reliability
If the coupling pawl is designed with multiple teeth for engagement, then reliable connection is achieved, but increased complexity in synchronization and engagement control results
Solution Approach 1:
The coupling pawl incorporates a control element that automatically detects engagement conditions and actuates the coupling without external intervention. The control element monitors system state (such as acceleration or tension) and autonomously engages or disengages the coupling pawl, eliminating the need for complex external synchronization control while maintaining reliable connection when engaged.
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
Enhances the direct transmission of drive force to the belt reel, minimizing interference during normal use and ensuring seamless operation of reversible and irreversible tensioners, while allowing automatic disengagement for irreversible activation.
Implementation Method 1
The belt reel is spring-loaded in the winding direction via a spring
Implementation Method 2
a friction-controlled coupling which, in order to establish the coupling connection, engages in an internal toothing of a clutch bell connected in a rotationally fixed manner to the belt shaft
Data Source
AI summary
A belt retractor for a seat belt device of a motor vehicle, comprising a rotatably mounted belt reel on which a seat belt of the seat belt device can be taken up, and a reversible belt tensioner comprising a drive wheel which drives the belt reel in the take-up direction upon an activation via the drive wheel, and a positively controlled tensioning coupler which transmits the drive movement from the drive wheel to the belt reel, comprising at least one coupling pawl which is mounted on the drive wheel and can be moved into and out of engagement with a toothing fixed on the belt reel in order to establish and neutralize a rotary connection of the drive wheel, and a control element comprising a first control contour for controlling the engagement movement of the coupling pawl into the toothing fixed on the belt reel.