Exit Device Assembly With Rotational Rod Actuation

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Solution Overview

Problem

Existing exit devices require high input force to actuate latches due to precise rod lengths and translation mechanisms, which can be cumbersome and inefficient.

Innovation Solution

An intermediate transmission assembly that translates input into rotational motion, reducing the need for precise rod lengths and minimizing the input force required to actuate upper and lower latches, using a rotatable input and crank link mechanism to facilitate easier door opening.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If traditional translation mechanisms with precise rod lengths are used, then latch actuation reliability is maintained, but input force requirement increases and operation becomes cumbersome

Engineering Contradiction:

Improveinput forceVSAvoidrod length precision

Core Design Contradiction:

ForceVSManufacturing precision

Solution Approach 1:

The patent replaces the traditional translation mechanism with a rotational mechanism. The vertical rod rotates about its longitudinal axis instead of translating linearly, and this rotational motion is transmitted through a crank link to actuate the latch. This substitution of rotational motion for translational motion reduces the input force required while maintaining reliable latch actuation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the motion parameter from linear translation to rotational movement. The vertical rod's longitudinal axis becomes the rotation axis, and the crank link converts this rotation into the appropriate motion for latch actuation. This parameter change allows the system to operate with lower input force while avoiding the need for precise rod length specifications.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If precise rod lengths and translation mechanisms are used, then latch actuation reliability is ensured, but device complexity increases

Engineering Contradiction:

Improvelatch actuation reliabilityVSAvoidmechanical complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent simplifies the mechanical system by replacing the complex translation mechanism with a simpler rotational mechanism. The vertical rod rotates about its longitudinal axis, and the crank link provides a straightforward conversion to latch actuation motion. This reduces the number of components and simplifies the overall mechanical arrangement while maintaining reliable operation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

Instead of using a vertical rod that translates linearly to actuate the latch, the patent inverts the approach by using a vertical rod that rotates about its longitudinal axis. The crank link then converts this rotation into the motion needed for latch actuation. This inversion of the motion type simplifies the mechanical arrangement.

Inventive Principle:

Principle #13The other way round (Inversion)

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

Reduces the input force needed to open doors by allowing for rotational movement of vertical rods, enhancing ease of operation and reducing mechanical complexity.

Implementation Method 1

The door latch assembly further comprises a cam and, and the rotatable input comprises a vertical rod

Methodology Applied

Scientific EffectCam mechanism: Cam

Data Source

PatentUS12435551B1Exit device assembly

Publication Date: 2025.10.07 DORMAKABA USA INC

AI summary

An exit device including an intermediate transmission assembly transmitting the translation of an input into a rotational vertical rod output is disclosed. An upper door latch receiving a rotational vertical rod input to actuate an upper door latch from a latched position to an unlatched position is further disclosed. A lower latch receiving a rotational vertical rod input to actuate a lower latch from a latched position to an unlatched position is additionally disclosed.