Vehicle Seat Fitting With Eccentric Epicyclic Gear
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Solution Overview
Problem
Existing vehicle seat fittings face challenges in adapting to project-specific strength requirements, particularly in crash scenarios, due to difficulties in optimizing dimensioning and material usage, which limits their effectiveness and efficiency.
Innovation Solution
The use of a fitting system with identical inner components and parametrized outer components, featuring an eccentric epicyclic gear system for continuous backrest adjustment, reduces material usage and weight by incorporating a flat enclosing ring and wedge segments, allowing for dynamic load retention and simplified manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the fitting uses a standardized gear system design, then the manufacturing and assembly are simplified, but the adaptation to project-specific strength requirements becomes difficult or impossible
Solution Approach 1:
The fitting is divided into identical parts (inner components) and parametrized components (outer components). The identical parts include elements like the driver, wedge segments, and retaining elements that remain the same across load classes. The parametrized components include the first fitting part, second fitting part, and enclosing ring that are adapted to different load classes. This segmentation allows standardized manufacturing of identical parts while enabling customization of parametrized parts for different strength requirements.
Solution Approach 2:
The fitting uses parameterized components where dimensions and proportions can be varied to meet different load class requirements. The first fitting part and second fitting part have dimensions that are adapted to specific load classes (1500 Nm, 2000 Nm, 2500 Nm), allowing the same basic design to be scaled and adjusted for different strength requirements while maintaining the same fundamental structure and manufacturing processes.
2Quantity of substance
If the toothed wheel is positioned on the radially outer edge of the second fitting part, then material and building space are saved, but the connecting areas for mounting the fitting are reduced
Solution Approach 1:
The toothed wheel is positioned on the radially outer edge of the second fitting part, utilizing the radial dimension efficiently. The enclosing ring is configured substantially flat rather than L-shaped, and axially protruding centering sections are distributed in the circumferential direction. This dimensional arrangement allows the toothed wheel to be placed at the outer edge to save material while the axial protrusions provide additional mounting surfaces in a different dimension, thus maintaining connecting areas without increasing overall material usage.
3Device complexity
If an eccentric epicyclic gear system is used instead of a planetary gear system, then the central pinion is eliminated saving components, but a wobbling movement is introduced that complicates the motion
Solution Approach 1:
The central pinion component is extracted/removed from the gear system. The eccentric epicyclic gear system uses only the toothed ring on the first fitting part and the toothed wheel on the second fitting part, eliminating the need for a central pinion. This reduces the number of components and simplifies the assembly while accepting the resulting wobbling motion as a trade-off for component reduction.
4Weight of moving object
If the enclosing ring is configured substantially flat instead of L-shaped, then weight and costs are reduced, but the engagement area with the first fitting part is reduced
Solution Approach 1:
The fitting parts utilize different material properties to compensate for the reduced engagement area. The first fitting part and second fitting part are made from materials with appropriate mechanical properties to ensure sufficient engagement strength despite the flat enclosing ring configuration. The material selection and dimensional optimization of the fitting parts compensate for the reduced contact area, maintaining overall engagement strength while reducing the enclosing ring material and weight.
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 solution enhances the fitting's ability to meet strength requirements across different load classes, enabling efficient and cost-effective production while ensuring continuous backrest adjustment and improved dynamic operating characteristics.
Implementation Method 1
The two fitting parts are connected to one another by means of a gear unit, in particular an eccentric epicyclic gear system
Implementation Method 2
The basic component of retaining the eccentric epicyclic gear system is provided by the friction between the eccentric and one of the two fitting parts
Implementation Method 3
The preferably provided wedge segments which define the eccentric serve for both, retaining and driving the rolling movement of toothed wheel and toothed ring
Data Source
AI summary
For a fitting for a vehicle seat, in particular for a motor vehicle seat, comprising a first fitting part and a second fitting part, which are in a transmission connection with each other by means of a spur gear and a ring gear, which mesh with each other, and comprising a rotating eccentric driven by a carrier for driving a relative rolling motion of the spur gear and the ring gear, wherein the first fitting part accommodates the eccentric, which is supported on the second fitting part, the fitting is associated with one of at least two load classes and comprises components that are parameterized in regard to the associated load class and components that are carry-over parts for all load classes, wherein the fitting parts are parameterized components and the eccentric is one of the carry-over parts.