Seat Linear Drive With Phased Propelling Teeth for Play-Free Motion
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Solution Overview
Problem
Existing linear drives for seat adjustment in motor vehicles face challenges in achieving smooth linear movement with minimal play and adjustable breaking loads, requiring complex designs and manufacturing processes.
Innovation Solution
A compact linear drive design featuring a rotatably arranged drive shaft with reciprocating propelling teeth and a gear rack, where the propelling teeth perform cyclical movements with a phase shift to generate propelling motion along the longitudinal axis, utilizing wedge-shaped friction surfaces for efficient power transmission and adjustable load handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a traditional spindle mechanism is used for linear drive, then the structure is simple, but the linear movement has play and the breaking load cannot be adjusted
Solution Approach 1:
The drive mechanism is segmented into multiple propelling teeth (at least two) that work in sequence on the gear rack, allowing each tooth to engage and disengage independently. This segmentation enables precise control of linear movement while distributing mechanical loads, eliminating play through phased engagement of multiple teeth rather than relying on a single continuous spindle contact.
Solution Approach 2:
The propelling teeth are designed to perform cyclical reciprocating movements with phase shifts during drive shaft rotation, creating dynamic engagement patterns with the gear rack. This dynamic mechanism allows the breaking load to be adjusted by controlling the phase shift and movement amplitude of the propelling teeth, while maintaining precise linear movement through controlled intermittent contact.
2Adaptability or versatility
If multiple propelling teeth with phase shift are used, then breaking load is adjustable and movement precision improves, but the device complexity increases
Solution Approach 1:
The propelling teeth mechanism serves multiple functions simultaneously: it provides adjustable breaking load through phase shift control, ensures precise linear movement through gear rack engagement, and enables fast adjustment speed through direct mechanical coupling to the drive shaft. This multi-functionality reduces the need for separate adjustment mechanisms, thereby limiting the increase in overall device complexity.
Solution Approach 2:
The propelling teeth perform cyclical reciprocating movements with defined periods during drive shaft rotation, creating periodic engagement patterns with the gear rack. This periodic action enables predictable and controllable breaking load characteristics while maintaining smooth linear movement, as the phased periodic engagement of multiple teeth distributes mechanical stresses and enables load adjustment without complex continuous control systems.
3Speed
If the propelling teeth engage the gear rack continuously, then the linear movement is smooth, but the adjustment speed decreases
Solution Approach 1:
The propelling teeth engage the gear rack in periodic cyclical movements rather than continuous contact, with at least two teeth performing reciprocating engagements with phase shifts. This periodic engagement pattern enables fast adjustment speed by allowing rapid engagement and disengagement cycles, while the overlapping phases of multiple teeth ensure continuous propelling force is maintained, preserving movement smoothness throughout the adjustment process.
Solution Approach 2:
Although individual propelling teeth engage and disengage periodically, the phased arrangement ensures that at least one tooth is always engaged with the gear rack, maintaining continuous useful propelling action. This continuity of propelling force across multiple teeth in sequence achieves both fast adjustment speed through rapid tooth cycling and smooth linear movement through uninterrupted force transmission to the gear rack.
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 enables smooth, virtually play-free linear movement with adjustable breaking loads and fast adjustment speed, improving the operational efficiency and reliability of the linear drive system.
Implementation Method 1
the propelling tooth and the tooth of the gear rack come into operative contact at so-called friction surfaces, from which the propelling motion results. For this purpose, it is necessary that at least the teeth and/or the propelling teeth have friction surfaces, which are designed in the manner of a wedge surface.
Data Source
AI summary
The present invention relates to a linear drive (1) having a drive shaft (10) along a longitudinal axis (X), at least two propelling teeth (20), and at least one gear rack (30) comprising a plurality of teeth (31), wherein the propelling teeth (20) are reciprocatingly movable perpendicularly to the longitudinal axis (X) and are drivingly connected to the drive shaft (10) such that said at least two propelling teeth (20) carry out at least one cyclical reciprocating movement (21) during the course of one rotation (φ) of the drive shaft (10), dipping into and out of the at least one gear rack (30) in order to produce propelling motion along the longitudinal axis (X), and wherein the cyclical reciprocating movement (21) of the at least two propelling teeth (20) have phase shifts (Δφ). Furthermore, the present invention relates to a longitudinal-adjustment unit as well as to a motor vehicle coprising such a longitudinal-adjustment unit.