Segmented Flock Drive Shaft for Vehicle Seat Rail Noise Reduction
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Solution Overview
Problem
Existing drive shaft assemblies in rail adjustment systems for vehicle seats experience undesired noise and vibrations due to the compression of flock fibers over time, especially at high rotational speeds, leading to operational issues during the expected lifespan.
Innovation Solution
The drive shaft assembly features sections with flock fibers arranged along the shaft axis, creating visible gaps and localized thickening, which are strategically applied to specific locations on the drive shaft's surface, avoiding uniform compression and influencing the natural frequency to reduce noise and vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If flock fibers are applied uniformly along the entire central part of the drive shaft, then play between the guide and drive shaft is reduced and noise is avoided during rotation, but uncontrolled compression and wear of flock fibers occurs over time leading to increased noise and vibrations
Solution Approach 1:
The flock fiber application is segmented into discrete sections along the shaft axis rather than continuous uniform coverage. These sections are spaced at specific intervals and create localized thickening zones that maintain contact with the guide while preventing uncontrolled compression of the entire flock fiber layer, thereby maintaining noise reduction properties throughout the operational lifespan
Solution Approach 2:
Different sections of the drive shaft receive different treatments: some sections have flock fibers applied creating localized thickening for noise reduction, while other sections between the flock fiber sections remain without flocking. This local differentiation allows specific zones to承担 the noise reduction function while preventing uniform compression across the entire shaft surface
2Object-affected harmful factors
If flock fibers are compressed to reduce play between guide and drive shaft, then noise during rotation is reduced, but the compressed flock fibers generate vibrations and noise after increased operating time
Solution Approach 1:
The drive shaft is divided into alternating sections: flock fiber sections that provide noise reduction through controlled contact with the guide, and gap sections without flocking that prevent uncontrolled compression. This segmentation ensures that only specific localized zones experience compression, maintaining vibration characteristics throughout the operational lifespan
Solution Approach 2:
The spaced arrangement of flock fiber sections creates a periodic structure along the shaft axis. This periodicity allows the drive shaft to maintain consistent vibration characteristics during rotation, as the regular spacing of thickening zones prevents chaotic vibration patterns that would arise from uniform or irregular flocking distribution
3Object-affected harmful factors
If sections with flock fibers are provided spaced along the shaft axis creating visible gaps, then uncontrolled compression is prevented and operational noise is reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The flocking process is simplified by segmenting it into discrete sections rather than requiring complex masking or selective application techniques. The spaced sections can be applied using straightforward flocking methods over specific zones, reducing manufacturing complexity compared to attempting uniform precise control
Solution Approach 2:
The invention changes the parameter of flock fiber distribution from uniform continuous coverage to discrete spaced sections. This parameter change simplifies the manufacturing process by allowing standard flocking techniques to be applied to defined zones, while the resulting structure naturally prevents uncontrolled compression and reduces operational noise
Data Source
AI summary
A drive shaft assembly, e.g. as part of a rail adjustment system for a vehicle seat, with a flexible drive shaft for transferring an adjustment force, is provided wherein the drive shaft has central part extending between the two shaft ends of the drive shaft, and the drive shaft is located with its central part at least partially in an elongate guide of the drive shaft assembly. At the central part of the drive shaft several sections arranged in the guide are provided with directly applied flock fibers, in a flocking process on a lateral surface of the drive shaft, which are spaced from each other along a shaft axis of the drive shaft and at which an outer diameter of the drive shaft is enlarged locally with regard to sections abutting these.