Vehicle Seat Joint Fine Tilt Adjustment Mechanism
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Solution Overview
Problem
Existing seat back articulations in vehicles face challenges in achieving a finer locking pitch while maintaining safety and robustness, as increasing the number of teeth reduces the depth of engagement, which is critical for shock resistance.
Innovation Solution
The implementation of multiple subsets of toothed grains with control cams and springs allows for a finer locking pitch by angularly offsetting the teeth, enabling one subset to be fully engaged while others are partially engaged, thereby reducing the locking pitch to less than 1.5 degrees or even 1 degree, while maintaining robustness through adequate engagement depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of teeth is increased to reduce locking pitch, then the locking pitch is reduced (improving adjustment precision), but the depth of engagement decreases (worsening shock resistance)
Solution Approach 1:
The locking mechanism is segmented into multiple independent subsets of locking grains (first subset with first grains, second subset with second grains, etc.). Each subset can engage independently with the base toothing, allowing the system to achieve fine adjustment precision through multiple engagement points while maintaining sufficient engagement depth at each point. The angular offset between subsets ensures that not all grains engage simultaneously, distributing the load and maintaining robustness.
2Measurement precision
If multiple subsets of toothed grains are introduced to achieve finer locking pitch, then the locking pitch is reduced (improving adjustment precision), but the device complexity increases
Solution Approach 1:
Multiple subsets of locking grains are merged into a single integrated locking mechanism that operates through one control hub. The control hub simultaneously controls multiple control cams (first control cam, second control cam, etc.), each associated with different subsets of grains. This merging approach achieves fine locking pitch through multiple engagement points while avoiding the complexity of multiple independent control systems.
Solution Approach 2:
The control hub serves multiple functions: it controls the radial displacement of locking grains from different subsets, manages the engagement/disengagement of multiple control cams, and coordinates the overall locking mechanism. This multi-functionality reduces the need for separate control mechanisms for each grain subset, thereby managing device complexity while achieving fine adjustment precision.
3Measurement precision
If the teeth are angularly offset to enable finer positioning, then the locking pitch is reduced (improving adjustment precision), but the manufacturing precision requirements increase
Solution Approach 1:
Different subsets of locking grains have different angular positions relative to the base toothing, creating local quality variations. The first subset's grains are at one angular position, while the second subset's grains are angularly offset by a specific difference. This local quality approach allows each subset to engage at different positions, achieving fine locking pitch while the angular offsets can be designed to accommodate reasonable manufacturing tolerances.
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 user comfort by providing a more precise adjustment mechanism while ensuring safety and robustness by maintaining significant engagement depth for shock resistance.
Implementation Method 1
a first control cam biased by one or more first springs, a second control cam biased by one or more second springs
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
Vehicle seat joint (10) allowing angular adjustment of a backrest relative to a seat, the joint comprising two flanges (7,8), the first flange comprising a basic toothing on an inwardly directed border, with N teeth spaced at an angular pitch of 360/N degrees, a series of first grains (21) cooperating with a first control cam (31) returned by first springs (41), a series of second grains (22) cooperating with a second control cam (32) returned by second springs (42), a control hub (1) for moving the control cams to an unlocking position against the first and second springs, wherein the teeth (27) of the series of first grains are angularly offset by at most half a tooth relative to the teeth (28) of the series of second grains, thus obtaining a locking pitch at least twice as fine.