Vehicle Seat Recliner Bolt Plastic Deformation Locking

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Solution Overview

Problem

Existing recliner mechanisms for vehicle seat backrests lack sufficient safety under overload conditions, such as during accidents, and require cost-effective improvements to maintain the backrest's fixed position.

Innovation Solution

A recliner mechanism featuring a bolt with a positive connection through plastic deformation between the bolt and a locking cam, which restricts rotation under radial overload forces, utilizing a toothed portion to prevent undesirable unlocking by engaging the latching pawl with the second fixing plate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a locking cam and latching pawl mechanism is used to maintain backrest position, then the backrest remains fixed during normal use, but the mechanism may undesirably unlock under overload conditions

Engineering Contradiction:

Improvebackrest position stabilityVSAvoidundesirable unlocking under overload

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by pre-deforming the bolt through plastic deformation before overload occurs. The bolt is designed with a deformation zone that will yield under predetermined overload conditions, creating a positive connection with the locking cam in advance to prevent unwanted unlocking during accidents while maintaining normal operation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent utilizes parameter changes by designing the bolt with specific material properties and geometric features (deformation zone) that change its mechanical behavior under different load conditions. The bolt transitions from an elastic state during normal use to a plastically deformed state under overload, fundamentally changing its interaction with the locking cam from free rotation to positive connection.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If structural reinforcement is added to prevent unlocking under overload, then safety improves, but manufacturing cost and complexity increase

Engineering Contradiction:

Improvesafety under overloadVSAvoidmechanism structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies self-service by designing the bolt to automatically deform and create a positive connection with the locking cam under overload conditions without requiring additional control systems, sensors, or complex mechanisms. The system uses the overload force itself to trigger the safety feature, eliminating the need for external control and reducing overall system complexity.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent employs a sacrificial bolt design where the bolt's deformation zone is intended to undergo permanent deformation under extreme overload conditions. This disposable element provides safety through a simple, low-cost plastic deformation mechanism rather than requiring expensive, complex redundant locking systems.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Ease of operation

If the locking cam is designed to allow free rotation for adjustment, then ease of operation is improved, but the mechanism becomes vulnerable to accidental unlocking

Engineering Contradiction:

Improvebackrest adjustmentVSAvoidresistance to accidental unlocking

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent applies dynamics by designing the bolt's mechanical properties to change its behavior based on load conditions. During normal operation, the bolt remains elastic and allows free rotation of the locking cam for adjustment. Under overload, the bolt transitions to plastic deformation, dynamically changing from a free-rotation state to a locked state that prevents accidental unlocking.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent applies preliminary anti-action by pre-configuring the bolt with a deformation zone that will counteract unwanted rotation under overload conditions. The plastic deformation capability is built into the bolt before use, creating a predetermined counter-force that activates only when excessive loads threaten to cause accidental unlocking.

Inventive Principle:

Principle #9Preliminary anti-action

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

Enhances safety by maintaining the backrest's fixed position during overloads while allowing normal operation without hindrance, with the ability to reset after the overload has subsided, thus ensuring passenger safety and ease of exit.

Implementation Method 1

Rotation of the second sub-assembly relative to the first sub-assembly is reduced by a positive connection between the bolt and at least one of the first sub-assembly and the second sub-assembly. According to one exemplary embodiment, the positive connection results from plastic deformation.

Methodology Applied

Scientific EffectPlastic deformation: Plasticity

Data Source

PatentUS7604297B2Adjusting mechanism and vehicle seat

Publication Date: 2009.10.20 KEIPER SEATING MECHANISMS CO LTD

AI summary

An adjusting mechanism includes a first sub-assembly, a bolt disposed on the first sub-assembly and a second sub-assembly. The bolt is configured to receive a force in a radial direction relative to an axis of the bolt. The second sub-assembly is mounted so as to be rotatable relative to the first sub-assembly by means of the bolt. The rotatability of the second sub-assembly relative to the first sub-assembly is configured to be reduced by a positive connection created using plastic deformation between the bolt and at least one of the first sub-assembly and the second sub-assembly.