Leg Rest Release Linkage for Obstruction-Safe Retraction

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Solution Overview

Problem

Furniture leg rest assemblies with powered actuators may continue to apply downward pressure after encountering an object, unaware to the occupant, due to lack of detection mechanisms during the return to the retracted position.

Innovation Solution

A release system incorporating a pantograph link with an engagement slot and an engagement pin, which allows the leg rest assembly to release from the engagement slot when an obstruction is encountered, enabling the assembly to return to the retracted position by gravity once the obstruction is cleared.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Extent of automation

If a powered actuator is used to operate the leg rest assembly, then the leg rest can be automatically extended and retracted, but the system cannot detect objects in the return path and may continue to apply downward pressure after encountering an object

Engineering Contradiction:

Improveautomatic operation of leg rest assemblyVSAvoiddetection of objects in return path

Core Design Contradiction:

Extent of automationVSReliability

Solution Approach 1:

The patent implements a feedback mechanism through the engagement slot and engagement pin system. When the leg rest assembly encounters an object during retraction, the engagement pin is forced out of the engagement slot, which signals the actuator to stop or reverse direction. This feedback loop allows the automated system to detect and respond to obstacles in the return path, preventing continuous downward pressure on objects.

Inventive Principle:

Principle #23Feedback

2Speed

If a ratchet and pawl assembly is used to hold the leg rest in extended position, then the return to retracted position can be rapid, but the system lacks the ability to release upon encountering an object

Engineering Contradiction:

Improvereturn speed to retracted positionVSAvoidrelease capability upon object contact

Core Design Contradiction:

SpeedVSAdaptability or versatility

Solution Approach 1:

The patent transforms the static ratchet-and-pawl locking mechanism into a dynamic system by introducing the engagement slot and engagement pin. The engagement pin can be inserted into or removed from the engagement slot depending on operational conditions. During normal retraction, the pin engages the slot for rapid return. When an object is encountered, the pin is forced out of the slot, allowing the system to adapt by stopping or reversing, thus providing both speed and release capability.

Inventive Principle:

Principle #15Dynamics

3Reliability

If the engagement pin is firmly held in the engagement slot during extension, then the leg rest assembly can be reliably extended, but the system cannot release when an obstruction is encountered

Engineering Contradiction:

Improveextension reliabilityVSAvoidrelease upon obstruction

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The engagement pin system is designed to be dynamically adjustable between engaged and disengaged states. During extension, the pin is firmly held in the engagement slot to ensure reliable operation. When an obstruction is encountered during retraction, the force from the object causes the pin to be forced out of the slot, allowing the system to release and adapt to the obstructed condition.

Inventive Principle:

Principle #15Dynamics

4Force

If continuous downward pressure is applied by the powered actuator, then the leg rest can be forcefully extended, but harmful pressure continues to be applied after encountering an object

Engineering Contradiction:

Improvedownward pressure applicationVSAvoidcontinuous pressure on encountered object

Core Design Contradiction:

ForceVSObject-affected harmful factors

Solution Approach 1:

The engagement slot and engagement pin create a feedback mechanism that monitors the return path for obstructions. When an object is encountered, the pin is forced out of the slot, which provides feedback to the actuator system to stop or reverse direction. This prevents continuous downward pressure from being applied to the encountered object, eliminating the harmful effect while maintaining the ability to apply force during normal operation.

Inventive Principle:

Principle #23Feedback

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

Ensures safe and automatic release of the leg rest assembly when encountering objects, preventing further pressure application and allowing smooth retraction, enhancing user safety and mechanism efficiency.

Implementation Method 1

enabling the assembly to return to the retracted position by gravity

Methodology Applied

Scientific EffectGravity: Gravitation

Data Source

PatentUS8366188B2Release system for furniture member leg rest assemblies

Publication Date: 2013.02.05 LA Z BOY INC

AI summary

A release system for a furniture member leg rest assembly extended from an actuation mechanism includes an actuation mechanism, the actuation mechanism having a leg rest assembly movable between a fully retracted and a plurality of extended positions inclusive, including a fully extended position. A pantograph link of the leg rest assembly is rotatably connected to the actuation mechanism. An extension link is rotatably connected to the actuation mechanism and moves in extension and retraction directions. A member is in contact with the extension link and in releasable contact with the pantograph link. The member is in contact with the pantograph link when the member is operating to push the pantograph link outward toward the fully extended position. The member is spatially separable from the pantograph link when an object is contacted by the leg rest assembly during return from any of the extended positions toward the fully retracted position.