Shallow Notch Headrest Rod Locking Mechanism

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Solution Overview

Problem

Existing headrest adjustment mechanisms in motor vehicles require significant material volume and depth for locking notches, leading to structural weakness, increased mass and cost, ergonomic issues, noise, and limited adjustment positions due to deep notches.

Innovation Solution

A sliding rod locking device with a reciprocal rack and pinion system, featuring shallow notches and teeth, allowing for multiple adjustment positions with reduced notch depth, improved ergonomics, and enhanced safety and comfort.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If deep notches are used for locking the rod, then the locking strength is improved, but the rod structure is weakened and mass increases

Engineering Contradiction:
Improvelocking strengthVSAvoidrod mass
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The locking mechanism is segmented into multiple notches distributed along the rod, with each notch providing partial locking capability. The blocking edge engages with multiple notches simultaneously or sequentially, distributing the locking load across several engagement points rather than relying on a single deep notch, thereby reducing the depth required for each individual notch while maintaining overall locking strength.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The solution transitions from relying on notch depth (one dimension) to utilizing the distribution of notches along the length of the rod (another dimension). By spacing multiple notches along the rod's length and having the blocking edge engage with multiple notches, the system achieves sufficient locking strength without requiring deep notches that would weaken the rod structure.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If deep notches are used for locking the rod, then the locking reliability is improved, but the number of adjustment positions is reduced

Engineering Contradiction:
Improvelocking reliabilityVSAvoidnumber of adjustment positions
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The locking mechanism is segmented into multiple notches distributed along the rod, with each notch providing partial locking capability. The blocking edge engages with multiple notches simultaneously or sequentially, distributing the locking load across several engagement points rather than relying on a single deep notch, thereby reducing the depth required for each individual notch while maintaining overall locking strength.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The solution transitions from relying on notch depth (one dimension) to utilizing the distribution of notches along the length of the rod (another dimension). By spacing multiple notches along the rod's length and having the blocking edge engage with multiple notches, the system achieves sufficient locking strength without requiring deep notches that would weaken the rod structure.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Strength

If deep notches are used for locking the rod, then the locking strength is improved, but the manufacturing complexity and cost increase

Engineering Contradiction:
Improvelocking strengthVSAvoidmanufacturing complexity
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The locking mechanism is segmented into multiple notches distributed along the rod, with each notch providing partial locking capability. The blocking edge engages with multiple notches simultaneously or sequentially, distributing the locking load across several engagement points rather than relying on a single deep notch, thereby reducing the depth required for each individual notch while maintaining overall locking strength.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent employs a blocking edge made of plastic or metal that can be easily manufactured and replaced if needed. This blocking edge engages with multiple shallow notches in the rod, providing sufficient locking strength without requiring complex deep notch formation processes. The simplicity of the blocking edge design and the shallow notches reduces manufacturing complexity and cost compared to creating deep notches.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

4Strength

If deep notches are used for locking the rod, then the locking strength is improved, but the ergonomics of operation deteriorate

Engineering Contradiction:
Improvelocking strengthVSAvoidergonomics
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The locking mechanism is segmented into multiple notches distributed along the rod, with each notch providing partial locking capability. The blocking edge engages with multiple notches simultaneously or sequentially, distributing the locking load across several engagement points rather than relying on a single deep notch, thereby reducing the depth required for each individual notch while maintaining overall locking strength.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The solution transitions from relying on notch depth (one dimension) to utilizing the distribution of notches along the length of the rod (another dimension). By spacing multiple notches along the rod's length and having the blocking edge engage with multiple notches, the system achieves sufficient locking strength without requiring deep notches that would weaken the rod structure.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP2774806B1Device for preventing the sliding of a ring-threaded shank for combining a headrest with a backrest of an automobile seat
Publication Date: 2016.04.06 CERA TSC
  • EP2774806B1 patent drawingFigure 1a~2b
  • EP2774806B1 patent drawingFigure 3a~3b
  • EP2774806B1 patent drawingFigure 4a~5b

AI summary

The device (1) has a blocking part (4) moving in radial translation relative to a sheath (3) receiving a ring-threaded shank (2). A releasing unit (7) radially spaces the part from the shank to release the shank. The part includes a blocking edge (5) in form of toothed rack with teeth (8). The shank includes a reciprocal toothed rack with notches (9). Inter-notch space is similar to inter-tooth space such that the notches receive the teeth to block the shank. The reciprocal toothed rack has height (10) greater than height (11) of the toothed rack to block shank according to height positions.