Seat Linear Drive With Phase-Shifted Rack Engagement
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Solution Overview
Problem
Existing linear drives for longitudinal seat adjustment in motor vehicles face challenges in achieving a play-free movement, adapting break loads, and maintaining quiet operation, which are essential for comfort and safety.
Innovation Solution
A linear drive design featuring a rack with equally distributed teeth and propulsion elements that perform cyclical stroke movements with a phase shift, driven by a transverse drive shaft, allowing for compact, play-free, and adaptable break load adjustment without additional gear units, utilizing helical gearing and camshaft disks for optimized contact and movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional spindle-based linear drive is used, then the structure is simple, but play-free linear movement cannot be realized and break loads cannot be adapted
Solution Approach 1:
The linear drive is segmented into multiple propulsion elements (at least two) that work independently but cooperatively. Each propulsion element has its own propulsion tooth that engages with the rack teeth, allowing the system to achieve play-free movement through distributed contact points while maintaining a relatively simple overall structure.
Solution Approach 2:
The drive shaft is designed to rotate dynamically, causing the propulsion elements to perform cyclical stroke movements. This dynamic operation allows the propulsion elements to enter and exit the rack in sequence, maintaining continuous engagement without play while adapting to varying break loads through the phase-shifted motion pattern.
2Volume of moving object
If additional gear units are added to achieve compact design, then the footprint is reduced, but the device complexity increases
Solution Approach 1:
The drive shaft combines multiple functions into a single component: it serves as both the rotating driver and the mechanical linkage for the propulsion elements. The propulsion elements themselves integrate the cam mechanism and propulsion tooth, eliminating the need for separate gear units and reducing overall device complexity while achieving compact dimensions.
Solution Approach 2:
The propulsion elements move in a stroke axis that is transverse to both the longitudinal axis (rack direction) and the transverse axis (drive shaft direction). This three-dimensional motion arrangement allows compact packaging of the drive mechanism without requiring additional gear units, as the stroke movement perpendicular to the rack direction enables space-efficient design.
3Productivity
If high adjustment speed is achieved, then productivity increases, but noise and friction increase reducing comfort
Solution Approach 1:
The propulsion elements perform periodic cyclical stroke movements as the drive shaft rotates. This periodic engagement and disengagement with the rack creates a rhythmical motion pattern that maintains high adjustment speed while distributing friction and noise over time, preventing continuous high-level noise and heat generation that would occur with constant sliding contact.
Solution Approach 2:
The phase-shifted cyclical stroke movements of multiple propulsion elements ensure continuous engagement with the rack, maintaining constant propulsion force and high adjustment speed without interruption. The overlapping engagement patterns of the propulsion elements ensure that at least one element is always in contact with the rack, providing continuous useful action while distributing the friction and noise load.
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
This design enables a compact, high-speed, and quiet linear movement with minimal play, allowing for efficient seat adjustment while ensuring safety and comfort by reducing friction and optimizing the number of components used.
Implementation Method 1
the propulsion tooth and the tooth of the rack come into operative contact at so-called friction surfaces, resulting in the propulsion
Data Source
AI summary
A linear drive has at least one rack which is arranged along a longitudinal axis and has a plurality of teeth, a drive shaft arranged in a transverse axis transversely to the longitudinal axis, and at least two propulsion elements, each having at least one propulsion tooth. The at least two propulsion elements are linearly movable in a stroke axis which is oriented transversely to the longitudinal axis and transversely to the drive shaft. The at least two propulsion elements are drivingly coupled to the drive shaft in such a manner that the at least two propulsion elements perform at least one cyclical stroke movement in the course of one rotation of the drive shaft and enter and exit the at least one rack to generate a propulsion in the longitudinal axis. The at least two propulsion elements enter and exit the at least one rack with a phase shift.