Overmoulded Headrest Sleeve Bushings for BSR Noise Damping
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Solution Overview
Problem
Existing sleeve devices for vehicle headrests face issues with noise due to tolerances and misalignment between rods and sleeves, leading to vibration and discomfort for users, while attempts to improve damping and sliding smoothness have been insufficient.
Innovation Solution
A sleeve device with overmoulded antifriction resilient plastic bushings at both ends of the inner and external seat portions to guide and absorb vibrations, allowing for secure positioning and reduced noise through a single manufacturing step.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the sleeve and rod are designed to fit tightly to avoid gaps, then noise problems (BSR) are reduced, but the metal rods cannot slide smoothly along the sleeves
Solution Approach 1:
The patent introduces an intermediary element (bushing or ring of flexible material) between the metal rod and the plastic sleeve body. This intermediary absorbs the tight fit requirements for noise reduction while providing the necessary compliance for smooth sliding motion, resolving the contradiction between noise reduction and sliding ease.
Solution Approach 2:
The patent changes the material parameters of the sleeve body by incorporating flexible material bushings or rings that can deform elastically. This allows the effective clearance between rod and sleeve to dynamically adjust - tight when stationary (reducing noise) and compliant during motion (enabling smooth sliding).
2Object-affected harmful factors
If elastomeric elements are placed between the frame and sleeve body to dampen noise, then vibration transmission is reduced, but the structure becomes complex
Solution Approach 1:
The patent merges the noise-dampening function with the existing sleeve body structure by integrating elastomeric elements as bushings or rings within the sleeve body itself, rather than adding separate damping components between the frame and sleeve. This consolidation reduces structural complexity while maintaining vibration dampening effectiveness.
Solution Approach 2:
The elastomeric bushings or rings serve multiple functions simultaneously: they act as bearing surfaces for the rod, provide noise dampening, accommodate tolerances, and enable smooth sliding. This multi-functionality eliminates the need for separate damping components, reducing overall structural complexity.
3Manufacturing precision
If the accommodation of the rod in the sleeve admits variances to compensate tolerances, then manufacturing flexibility is improved, but noise is generated by vibration during driving
Solution Approach 1:
The patent changes the material parameters of the sleeve-rod interface by introducing flexible elastomeric bushings or rings. These materials can deform to accommodate manufacturing tolerances in rod diameter and sleeve clearance while maintaining consistent contact pressure, thereby preventing the loose fits that lead to vibration-induced noise.
Solution Approach 2:
The patent employs composite construction by combining plastic sleeve body material with elastomeric bushing material. This composite approach allows the rigid plastic to maintain structural integrity while the flexible elastomeric portion accommodates tolerances and dampens vibrations, preventing noise generation.
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 sleeve device effectively reduces noise and vibration, providing a smooth sliding experience for the headrest while accommodating manufacturing tolerances, thus addressing the BSR (Buss Squeak Rattle) issues and ensuring a pleasant user experience.
Implementation Method 1
an upper inner bushing (7) overmoulded to the upper inner seat portion (6), the upper inner bushing (7) being made from an antifriction resilient and soft plastic material and comprising an inner axial opening for guiding the rod (18) of the headrest
Implementation Method 2
so that transmission of vibrations from the frame to the rod of the headrest and generation of noise is reduced
Implementation Method 3
damping of the noise can only be achieved in an insufficient manner
Implementation Method 4
the upper inner bushing (7) being made from an antifriction resilient and soft plastic material
Data Source
Figure 1
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AI summary
A sleeve device for a headrest comprising a sleeve body (1) to be inserted into an opening in a frame of a vehicle seat, the sleeve body (1) comprising an inner axial passage (2) to accommodate a rod (18) of the headrest, the inner axial passage (2) including an inner wall (2a), a top end portion (2b) and a bottom end portion (2c); a head portion (3) ;an external side (1a); and an upper inner seat portion (6) at the inner the wall (2a) of the top end portion (2b) of the axial passage (2), the upper inner seat portion (6) for encircling an upper portion of the rod (18) of the headrest; and an upper inner bushing (7) overmoulded to the upper inner seat portion (6), the upper inner bushing (7) being made from an antifriction resilient plastic material and comprising an inner axial opening for guiding the rod (18) of the headrest.