Rear Seat Backrest Cam Locking for Four Crash-Compliant Positions

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Solution Overview

Problem

Current vehicle rear seat backrests are limited to a few positions, primarily focused on passenger comfort, and can only withstand crash tests within a narrow inclination range (20° to 32°), leading to reduced user options due to cost and regulatory constraints.

Innovation Solution

A rear seat with a backrest that can pivot around an axis of rotation, utilizing two cams with offset hollow impressions to create four distinct notches, allowing the backrest to occupy various inclinations, each designed to resist crash tests, and an unlocking mechanism to facilitate easy adjustment and secure locking in desired positions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the backrest is limited to a narrow inclination range (20° to 32°) to meet crash test regulations, then safety compliance is achieved, but the number of available positions is reduced

Engineering Contradiction:
Improvecrash test complianceVSAvoidnumber of backrest positions
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The backrest adjustment mechanism is segmented into multiple discrete notches within the 20° to 32° inclination range. Each notch represents a specific approved position that meets crash test requirements, while collectively providing multiple usable positions for different functions (seating, child seats, trunk access).

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The backrest mechanism transitions from a static fixed-position design to a dynamic multi-position system. The releaseable locking mechanism allows the backrest to move between discrete notches, adapting to different functional requirements while maintaining safety compliance at each position.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If multiple discrete backrest positions are provided to enhance versatility, then adaptability is improved, but the mechanism complexity increases

Engineering Contradiction:
Improvenumber of backrest positionsVSAvoidadjustment mechanism complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The backrest adjustment mechanism is designed to be self-servicing through its simple locking and release mechanism. The user can easily move the backrest between notches by releasing and re-engaging the locking mechanism, without requiring complex controls or assistance. The mechanism automatically maintains its position at each notch through the locking action.

Inventive Principle:
Principle #25Self-service

3Adaptability or versatility

If the backrest can pivot to multiple inclinations for different functions, then versatility is improved, but the structural complexity increases

Engineering Contradiction:
Improvefunctional positionsVSAvoidstructural complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The continuous arc of the backrest movement is segmented into discrete functional notches. Each notch corresponds to a specific inclination angle optimized for a particular function (normal seating, child seat installation, trunk access). This segmentation allows the structure to be simple while providing multiple specialized positions.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A single backrest structure serves multiple functions by pivoting to different notched positions. The same physical component (the backrest) adapts to different uses: passenger seating comfort, child seat installation stability, and trunk volume maximization, without requiring separate structures for each function.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP4477465A1Vehicle comprising a rear seat with a backrest which can be pivoted into at least four positions
Publication Date: 2024.12.18 RENAULT SA
  • EP4477465A1 patent drawingFigure 1
  • EP4477465A1 patent drawingFigure 2
  • EP4477465A1 patent drawingFigure 3~4

AI summary

The invention relates to a vehicle (1) comprising a rear seat (2) having a seat (3) and a backrest (4) mounted pivoting around an axis of rotation (9).According to the invention, the backrest (4) has a drive piece (17) through which the rotation axis (9) passes and which includes a circular arc-shaped peripheral portion from which a pin (18) emerges. The vehicle comprises two cams (15, 16) placed side by side, each having at least two hollow recesses. The two cams (15, 16) are arranged relative to each other such that the two hollow recesses of one cam (15, 16) are offset from the two hollow recesses of the other cam (15, 16). Rotating the backrest (4) causes a simultaneous rotation of the drive piece (17), allowing the pin (18) to engage in a hollow recess of one of the two cams (15, 16). The insertion of the pin (17) into a hollow recess of one of the... two cams (15, 16) locking the backrest (4) in a position corresponding to a given inclination.