Vehicle Seat Drive Friction Ring for Reducer Play Masking

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Solution Overview

Problem

Motorized training devices for vehicle seats often exhibit a noticeable functional game due to the reducer's operation, which can be distracting during location changes such as when a occupant sits or leaves the seat, and existing solutions fail to effectively mask this game.

Innovation Solution

A motorized training device with an actuator housing containing a reducer, an output organ with a friction ring that includes a skirt in contact with an inner level, creating a friction brake effect, which masks the reducer's game by requiring a torque above a predetermined threshold to turn the output organ, thus minimizing noticeable movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a reducer with functional clearance is used to achieve high reduction ratio, then the seat raising movement can operate in all circumstances, but noticeable gear play occurs when load polarity changes

Engineering Contradiction:
Improveoperational reliabilityVSAvoidgear play
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

A friction ring is introduced as an intermediary element between the output pinion and the inner bearing. This friction ring creates a friction brake that masks the functional clearance of the reducer, preventing noticeable gear play while maintaining operational reliability. The friction ring acts as a mediator that absorbs the clearance effect through frictional resistance.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If a friction brake is applied to mask reducer play, then gear play is reduced, but additional friction elements increase device complexity

Engineering Contradiction:
Improvegear play reductionVSAvoidstructure complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The friction ring is merged with the existing actuator housing structure. The inner bearing is integrated into the housing, and the friction ring is positioned between the output pinion and the bearing, combining multiple functions (support, friction braking, and clearance masking) into a unified structure rather than adding separate independent components.

Inventive Principle:
Principle #5Merging (Combining)

3Ease of operation

If a torque threshold is required to overcome friction brake, then functional clearance is masked, but energy consumption increases

Engineering Contradiction:
Improveclearance maskingVSAvoidenergy consumption
Core Design Contradiction:
Ease of operationVSUse of energy by moving object

Solution Approach 1:

The friction coefficient and normal force parameters of the friction brake are optimized to achieve the desired torque threshold for masking clearance while minimizing energy consumption. By adjusting these parameters, the system requires sufficient torque to mask the functional clearance during normal operation, but the energy penalty is minimized through proper parameter selection.

Inventive Principle:
Principle #35Parameter changes

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 solution effectively masks the reducer's game by ensuring the output organ only turns when a sufficient torque is applied, providing a smoother operation and reducing the noticeable functional game, with a braking torque of at least 3 N.m, thus enhancing user experience.

Implementation Method 1

a friction ring mounted around said output member and integral in rotation with said output member, the friction ring comprising a skirt, the actuator housing comprising an inner bearing for receiving said skirt, the skirt being in contact with at least said inner bearing to form a friction brake between said output member forming a rotating part and said inner bearing forming a fixed part

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP4272998B1Motorised drive device for hight adjustable vehicle seat
Publication Date: 2025.02.12 FAURECIA SIEGES D AUTOMOBILE SA
  • EP4272998B1 patent drawingFigure 1~2
  • EP4272998B1 patent drawingFigure 3~4
  • EP4272998B1 patent drawingFigure 4A~6

AI summary

Motorized drive device for vehicle seat having a seat in particular with a riser, the device comprising an actuator (13) and an actuator housing (10) containing a reducer (8), an output member (3), mounted for rotation about an axis (A1), the output member comprising a peripheral rim (2), a friction ring (4) mounted around the output member and rotationally fixed to the output member, the friction ring comprising a skirt (5), the actuator housing comprising an inner bearing (1) optionally provided with a plurality of internal radial projections (1a) to receive the skirt, the skirt coming into contact at least against the inner bearing to generate continuous friction between the output member forming a rotating part and the inner bearing forming a fixed part.