Exit Device Coordination Mechanism for Flexible Cable Latch Retention

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Solution Overview

Problem

Existing exit devices with remote latching assemblies face issues such as premature extension of the bottom bolt causing drag on the floor, reduced structural integrity due to large cutouts for rods, and inability of flexible cables to transmit pushing forces, complicating selective bolt retention.

Innovation Solution

A pushbar assembly with a coordination mechanism that biases the latch control assembly toward its actuated state, using flexible cables for connectors, and includes a mechanism to selectively retain the latch mechanisms in an actuated state until a threshold force is exceeded, allowing for concealed installation without compromising structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If rigid rods are used to connect latch mechanisms, then the top latch mechanism can exert a pushing force to retain the lower rod in its raised position, but rods require much larger cutouts than cables, reducing structural integrity of the door

Engineering Contradiction:

Improvelatch retention reliabilityVSAvoiddoor structural integrity

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent replaces rigid rod connectors with flexible cable connectors that run through guide members. This substitution allows the use of flexible cables instead of rigid rods, enabling smaller cutouts in the door while maintaining the ability to transmit forces for latch retention.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces guide members as intermediary components that constrain the movement of flexible cables. These guide members ensure the cables follow a predetermined path and can transmit both pulling and pushing forces, enabling the flexible cable system to achieve the same retention functionality as rigid rods.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If flexible pull cables are used for connectors, then smaller cutouts are allowed, but their inability to transmit pushing forces complicates the selective retention of the bottom bolt in its retracted position

Engineering Contradiction:

Improvedoor structural integrityVSAvoidlatch control mechanism complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs a coordination mechanism with a spring that dynamically adjusts the state of the latch control assembly. The spring biases the assembly toward the actuated state, automatically coordinating the movement of both latch mechanisms without requiring complex control systems.

Inventive Principle:

Principle #15Dynamics

3Reliability

If retention mechanisms are incorporated in surface-mounted remote latching assemblies, then the desired functionality is achieved, but these retention mechanisms typically cannot be mounted within the pushbar assembly itself, restricting design flexibility

Engineering Contradiction:

Improvelatch coordination reliabilityVSAvoidmounting location flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent designs the coordination mechanism to be mounted within the pushbar assembly, allowing it to serve multiple functions: coordinating both latch mechanisms, providing the retention function, and biasing the latch control assembly. This multi-functional design eliminates the restriction of mounting location and enhances design versatility.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 prevents premature extension of the bottom bolt, maintains structural integrity, and allows for flexible cable use in concealed remote latching assemblies, enhancing operational reliability and aesthetics.

Implementation Method 1

the coordination mechanism includes a spring operable to urge the latch control assembly toward the actuated state

Methodology Applied

Scientific EffectSpring: Spring

Data Source

PatentUS12410636B2Exit device coordination mechanisms

Publication Date: 2025.09.09 SCHLAGE LOCK CO LLC

AI summary

An exemplary exit device includes a pushbar assembly, a remote latching assembly, and a coordination mechanism. The pushbar assembly includes a latch control assembly, and the coordination mechanism biases the latch control assembly toward its actuated state. The remote latching assembly includes first and second latch mechanisms, and the latch control assembly is operable to actuate the latch mechanisms. Each of the latch mechanisms at least selectively urges the latch control assembly toward its deactuated state such that the remote latching assembly exerts a variable deactuating force on the latch control assembly. The coordination mechanism selectively retains the latch control assembly in its actuated state, thereby selectively retaining at least one of the latch mechanisms in a corresponding actuated state. When the deactuating force exceeds a threshold force value, the latch control assembly and the latch mechanisms return to the deactuated states thereof.