Vehicle Seat Catch Assembly Dynamics for Friction Reduction
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Solution Overview
Problem
Existing vehicle seat fittings struggle with unintentional backrest movement due to geometry changes, leading to increased static friction and complex handling mechanisms, which complicate the 'easy-entry' function and crash safety considerations.
Innovation Solution
A pawl arrangement with a rolling contact mechanism between the pawl and counter-element, utilizing a self-locking eccentric planetary gear and a multi-part pawl design with a spiral spring, minimizes static friction and simplifies the handling of the backrest's free-pivoting function, allowing independent adjustment of the backrest inclination and seat position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple pawl is used to prevent backrest movement, then the structure is simple, but static friction increases and handling becomes complex
Solution Approach 1:
The patent transforms the static pawl structure into a dynamic system where the pawl can automatically swing open and engage with the counter-element based on backrest position. The pawl is spring-loaded to maintain contact pressure, enabling automatic engagement without manual intervention, thus improving ease of operation while keeping the structure relatively simple.
Solution Approach 2:
The pawl arrangement is designed to automatically engage and disengage based on backrest movement forces. When the backrest is moved forward, the pawl swings open automatically; when the backrest returns to its original position, the pawl automatically engages with the counter-element. This self-service mechanism eliminates the need for complex manual control systems.
2Device complexity
If sliding movement is used between pawl and counter-element, then the structure is simple, but friction increases
Solution Approach 1:
The patent introduces a rolling contact mechanism where a roller is mounted on the pawl to contact the counter-element. This dynamic rolling contact replaces static sliding contact, significantly reducing friction forces while maintaining the simplicity of the overall structure. The roller rotates as the pawl moves, converting sliding friction into rolling friction.
3Stability of the object's composition
If the backrest is fixed in freely pivoted position, then stability is improved, but crash safety requirements become more stringent
Solution Approach 1:
The patent employs a spring-loaded pawl mechanism where the spring force can be adjusted to provide appropriate preloading. This parameter adjustment allows the system to maintain stable positioning during normal operation while allowing controlled movement during crash events. The spring force parameter can be optimized to balance stability and safety requirements.
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 enhances the 'easy-entry' function by ensuring the backrest can be easily pivoted back when the seat reaches the set longitudinal position, reducing friction and simplifying the mechanism, thus improving user handling and safety by minimizing static friction and maintaining effective locking without sliding friction.
Implementation Method 1
a spiral spring (36) acting on the pawl arrangement (34) with a force
Implementation Method 2
the locking bolt (18a) has a roller (18b), in particular a plain bearing or a roller bearing, mounted on it, by means of which rolling movement and no sliding movement occurs in the contact area
Data Source
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AI summary
In a fitting (5) for a vehicle seat, a catch assembly (34) has a pivot axis (B), and the catch assembly (34) further has a catch (34a) and a lever (34c) which can be pivoted relative to one another about an axis which is spaced from the pivot axis (B). The catch (34a) is designed with a hook-like contour in an end region (34a') and in the pivoted-out position of the backrest (2) said catch engages with a catch locking element (18) for locking in a punctiform or linear contact region (C). The catch (34a), in particular the other end (34a") of the catch (34a), cooperates with a spring (36). In the region of a first end, the lever (34c) is mounted pivotably about the pivot axis (B) and in the region of the opposing second end said lever rotatably mounts the catch (34a). In the unloaded pivoted-out position, the perpendicular in the contact region (C) runs on one side of the pivot axis (B) or through the pivot axis (B), resulting in the generation of a torque which closes the catch (34a) or no torque, and when a return pivoting force is imposed on the backrest (2) in the pivoted-out position, the perpendicular in the contact region (C) runs on the opposing side of or outside of the pivot axis (B), resulting in the generation of a torque which opens the catch (34a).