Self-locking Belt Retactor Control Clip for Rattle Noise Reduction
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Solution Overview
Problem
Self-locking belt retractors experience issues with unwanted rotational springback and noise generation due to inertia and sudden braking, leading to control problems and undesirable rattle noises, especially when the seatbelt is unlatched or during small vibrations.
Innovation Solution
A control clip with legs that overlap the follower and a damping component is used to prevent the inertia element from swiveling during belt winding and fix the locking element, reducing noise by frictionally locking the pin in the oblong hole, and an external gear mechanism is introduced to manage vehicle-sensitive control mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the winding spring rotates the belt shaft at high speed during belt retraction, then the belt winding function is improved, but the inertia causes unwanted rotational springback and activates the control mechanism falsely
Solution Approach 1:
The control clip is designed to dynamically change its locking state based on rotational direction. During forward rotation (belt retraction), the clip's geometry allows free rotation. During reverse rotation (springback), the clip engages to prevent false activation, thus adapting the system's constraints to different operational phases
Solution Approach 2:
The control clip acts as an intermediary element between the belt shaft and the control mechanism. It selectively transmits or blocks rotational movement based on direction, preventing unwanted signal transmission to the control mechanism during springback while allowing normal operation during active retraction
2Ease of operation
If the pin is allowed to move freely in the oblong hole during relative rotation, then the control mechanism flexibility is improved, but rattle noises are generated
Solution Approach 1:
The control clip applies localized frictional locking at specific positions within the oblong hole rather than constraining the pin throughout its entire travel path. This allows the pin to move freely where control flexibility is needed while providing friction-based noise suppression at critical positions
Solution Approach 2:
The frictional locking mechanism changes the effective clearance parameter between the pin and oblong hole. Under normal operation, full clearance is available for flexibility. Under certain conditions, frictional engagement reduces the effective clearance to eliminate rattling, thus dynamically adjusting the mechanical parameter
3Manufacturing precision
If the inertia element is prevented from swiveling during belt winding, then control precision is improved, but the inertia element cannot respond to angular acceleration
Solution Approach 1:
The control mechanism dynamically adjusts the inertia element's degrees of freedom based on operational mode. During belt winding, the inertia element is constrained to maintain control precision. During belt payout or sudden acceleration events, the constraint is released to allow proper inertial response
Solution Approach 2:
The control system periodically engages and disengages the inertia element constraint based on the operational cycle. The control clip alternates between locked and free states depending on whether the belt is being retracted or paid out, creating a periodic pattern of constraint that matches the operational rhythm
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 effectively prevents unwanted rotational springback and noise by ensuring the inertia element can freely swivel during belt extension and fixes the locking element in the belt winding direction, reducing rattle noises and improving the overall functioning of the belt retractor.
Implementation Method 1
a belt shaft (1) mounted rotatably in a housing frame (2) and tensioned by a winding spring (3) in the winding direction of the seat belt
Implementation Method 2
the control disc (10) carries a two-armed inertia element (15) eccentrically swivel-mounted on the control disc that, when triggered, swivels radially against the action of the return spring with its one blocking arm until it engages into a stationary toothed section owing to the angular acceleration acting on the control disc
Implementation Method 3
swivels radially against the action of the return spring
Implementation Method 4
a control clip (25) having two legs that are spaced apart from each other in the peripheral direction is mounted in a mounting point for the belt shaft and/or the control disk by means of a friction mount relative to the control disc
Data Source
AI summary
A self-locking belt retractor for seat belts having a belt-strap-sensitive control mechanism with a control disc coupled to the belt shaft to control a locking element, by means of a pin moveably in an oblong hole in the control disc. The control disc carries an inertia element that, when triggered, radially swivels to lock the retractor belt shaft engages into a stationary toothed section. A control clip has two spaced apart legs on a friction mount between a blocking position of the inertia element and a release position. A follower forms stop surfaces engageable with the clip legs to carry the control clip during the rotation of the control disc belt winding direction a belt extension direction. The control clip releases the inertia element in the release position. One spring leg extends with an end into the movement path of the pin in the oblong hole.