Magnetic REX Sensor for Door Lockset Wear Reduction

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Solution Overview

Problem

Existing REX switches in door locksets, which rely on electromechanical switches, are prone to failure due to wear and malfunction from repeated actuation, leading to potential security breaches.

Innovation Solution

A sensor assembly for door locksets that includes a mounting member, a rotatable member, and a sensor configured to detect rotation, eliminating the need for electromechanical switches by using a magnetic attraction mechanism to activate the sensor upon rotation of the latch operator, thereby sending a request to exit signal to the controller.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electromechanical switches are used in the REX switch mechanism, then the device can detect door opening from the inside, but the switch is prone to failure due to wear and malfunction from repeated actuation

Engineering Contradiction:

Improvereliability of REX switchVSAvoidservice life of electromechanical switch

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent replaces the electromechanical switch with a magnetic field-based sensor system. A magnet is attached to the rotatable member, and a reed switch or Hall effect sensor detects its position through the wall of the rotatable member without mechanical contact. This eliminates wear from repeated actuation while maintaining the ability to detect door opening from the inside, directly resolving the reliability and service life contradiction.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If a sensor is mounted inside the rotatable member to detect rotation, then the REX function can be achieved, but the sensor may be damaged from repeated actuation and wear

Engineering Contradiction:

Improvereliability of sensor detectionVSAvoidwear and damage to sensor

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent uses the wall of the rotatable member as an intermediary barrier that protects the sensor while allowing magnetic field penetration. The magnet is positioned such that its magnetic field passes through the wall to actuate the reed switch or Hall effect sensor, which remains protected inside the rotatable member. This intermediary structure eliminates direct exposure to wear and damage while maintaining detection functionality.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If the REX switch uses mechanical components that rotate and actuate, then the door opening detection function works, but the components are subject to breakage from repeated actuation

Engineering Contradiction:

Improvedoor opening detection functionVSAvoidresistance to breakage of mechanical components

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The patent replaces mechanical actuation components with a magnetic field-based detection system. The magnet rotates with the rotatable member, and its magnetic field actuates the reed switch or Hall effect sensor without mechanical contact. This substitution maintains the ease of operation for detecting door opening while eliminating the strength limitations of mechanical components subjected to repeated actuation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 enhances the reliability and durability of the REX switch mechanism, reducing the likelihood of failures and ensuring secure operation by using a magnetic attraction mechanism that is less susceptible to wear and tear, thus maintaining security without the limitations of electromechanical switches.

Implementation Method 1

using a magnetic attraction mechanism to activate the sensor upon rotation of the latch operator

Methodology Applied

Scientific EffectMagnetic attraction: Magnetism

Data Source

PatentUS8690205B2Door lockset

Publication Date: 2014.04.08 ASSA ABLOY ACCESSORIES & DOOR CONTROLS GROUP INC

AI summary

A sensor assembly for generating a request to exit (REX) signal for a door lockset operable with a latch operator and a controller that can signal an alarm. In one embodiment, the sensor assembly includes a mounting member adapted to be in a fixed position in the door lockset, a rotatable member adapted to rotate in response to rotation of the latch operator, and a sensor mounted to the mounting member. The sensor is spaced from the rotatable member and is configured to detect rotation of the rotatable member. When the rotatable member is rotated corresponding to rotation of the latch operator, the sensor detects the rotation, and a switch in the sensor, which may be magnetic, is actuated, closing a circuit to send a REX signal to the controller. The sensor assembly may be associated with a chassis of the door lockset.