Vehicle Seat Recliner Fitting Cam Arrangement Load Limiting
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Solution Overview
Problem
Existing vehicle seat recliner fittings are prone to damage from high loads applied to the hand lever, leading to unnecessary twist and deformation of the connection between the shaft and locking device, which can result in improper movement of the hand lever in both use and non-use positions.
Innovation Solution
A recliner fitting design featuring a shaft connected to a hand lever, with a locking device and a cam arrangement that includes a handle load element and clip element to limit movement and prevent high loads from being transferred to the locking device, incorporating a two-way clip for connection to the driving element and handle load element, and a cam arrangement to define the angle of the hand lever in both use and non-use positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the hand lever is connected directly to the locking device via the shaft, then the locking device can be actuated to adjust the backrest angle, but high loads applied to the hand lever cause unnecessary twist and deformation of the connection between the shaft and locking device
Solution Approach 1:
A cam arrangement is introduced as an intermediary element between the shaft and the locking device. The cam arrangement includes a cam surface that interacts with a follower, allowing the shaft to rotate and actuate the locking device while preventing the transmission of high loads and twisting forces to the shaft connection. This mediator absorbs the harmful loads while transmitting the necessary actuation motion.
2Ease of operation
If the hand lever allows free movement, then the passenger can easily adjust the backrest angle, but the hand lever can be subjected to high loads causing damage to the locking structure
Solution Approach 1:
The cam arrangement is designed to provide beforehand cushioning by limiting the movement range of the hand lever. The cam surface geometry defines specific start and end positions for the adjustment range, preventing the hand lever from being pulled with excessive force that could damage the locking structure. The follower rides along the cam surface within predetermined limits, cushioning against misuse forces.
3Strength
If the shaft connection is made robust to handle high loads, then the connection can withstand misuse forces, but the complexity of the fitting increases
Solution Approach 1:
The cam arrangement serves as a protective intermediary that shields the shaft connection from high loads. Instead of making the shaft connection more robust to handle misuse forces, the cam mechanism absorbs these forces before they can reach the shaft. This approach maintains the simplicity and robustness of the shaft connection while providing the necessary protection against excessive loads.
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 design effectively prevents damage from misuse forces by limiting the angle of the hand lever and avoiding overtwist, providing a customizable solution that can be used independently of seat design, while simplifying assembly with a single weld and eliminating the need for a pushnut.
Implementation Method 1
The handle load element includes a cam arrangement for following the recess surface and for forming a stop with the end surface to limit movement of the cam arrangement and to prevent a transfer of high loads from the hand lever to the locking device
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A vehicle seat is provided, in particular motor vehicle seat, including a seat part (3) and a backrest (4) which are connected by recliner fittings (5) that are connected together by a shaft (7) connected to a hand lever (9) for unlocking each recliner fitting to adjust an angle of the backrest relative to the seat base The fitting has a first fitting part (11) and a second fitting part (12) mounted to be rotatable relative to each other about an axis of rotation. The second fitting part has inwardly facing toothing which extends along at least a portion of an arc. A locking device with a driving element (27) is connected to the shaft and locking elements movable in response to rotation of the shaft, each of the locking elements having a radial outward side with at least one tooth for engaging the toothing of the second fitting part when the locking element is in a locking position, one of the first fitting part and the second fitting part having an outer surface defining a recess having a recess surface with an end surface (38). A clip element (40, 70) is connected to the driving element (27) and a handle load element (50, 80) is fixed to the shaft (7) and is connected to the clip element (40, 70). The handle load element (50, 80) extends radially outward from the shaft (7) and includes a cam arrangement (52) forming a stop with the end surface (38) to limit movement of the cam arrangement (52) and to prevent a transfer of high loads from the hand lever to the locking device.