Passive Infrared Detection for Elevator Hoistway Safety

Solution Overview

Problem

Elevator safety systems face challenges in efficiently detecting and clearing unauthorized access and ensuring safety without causing unnecessary shutdowns, leading to increased service costs and inconvenience, especially in cases where brief openings of hoistway doors do not result in personnel presence.

Innovation Solution

A system utilizing passive infrared detectors positioned on top, below, and in the pit area of the elevator car, coupled with a local processor, to detect the presence of persons and open landing doors, allowing for automatic reset of the elevator system when no personnel are detected, thereby preventing false shutdowns and enabling safe operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If manual reset by service personnel is required after hoistway door opening, then safety is ensured, but service costs increase and convenience decreases

Engineering Contradiction:

ImprovesafetyVSAvoidconvenience

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The system automatically detects whether personnel are present in the hoistway using sensors and autonomously determines whether to permit elevator operation without requiring manual intervention. The controller self-services by monitoring sensor inputs and automatically clearing shutdown conditions when safe, eliminating the need for service personnel to manually reset the system after every door opening event.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The manual mechanical reset process is replaced with an automated electronic detection and control system. Sensors detect personnel presence and transmit signals to the controller, which then automatically manages the safety chain and elevator operation, substituting human mechanical intervention with electronic automation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If manual reset by service personnel is required after hoistway door opening, then safety is ensured, but service costs increase

Engineering Contradiction:

ImprovesafetyVSAvoidservice costs

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system automatically detects whether personnel are present in the hoistway using sensors and autonomously determines whether to permit elevator operation without requiring manual intervention. The controller self-services by monitoring sensor inputs and automatically clearing shutdown conditions when safe, eliminating the need for service personnel to manually reset the system after every door opening event.

Inventive Principle:

Principle #25Self-service

3Reliability

If elevator system shuts down after abnormal hoistway door opening, then personnel safety is protected, but elevator functionality is lost

Engineering Contradiction:

Improvepersonnel safetyVSAvoidelevator functionality

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system dynamically adjusts elevator operation based on real-time sensor feedback. When sensors detect no personnel in the hoistway, the controller dynamically permits operation. When personnel are detected, the system dynamically shuts down to ensure safety. This dynamic response allows the elevator to maintain functionality when safe while protecting personnel when necessary.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

Sensors continuously monitor the hoistway for personnel presence and provide feedback to the controller. The controller uses this feedback to automatically determine whether to permit or prohibit elevator operation, creating a closed-loop safety system that maintains elevator functionality when conditions are safe while ensuring shutdown when personnel are present.

Inventive Principle:

Principle #23Feedback

4Ease of operation

If automatic reset is implemented without personnel detection, then convenience improves, but false shutdowns may occur

Engineering Contradiction:

ImproveconvenienceVSAvoidfalse shutdowns

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The manual mechanical reset process is replaced with an automated electronic detection and control system. Sensors detect personnel presence and transmit signals to the controller, which then automatically manages the safety chain and elevator operation, substituting human mechanical intervention with electronic automation.

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 system effectively detects personnel presence and open doors, allowing for controlled elevator motion and automatic reset, reducing service costs and ensuring safety without unnecessary shutdowns, thus maintaining elevator functionality and safety.

Implementation Method 1

A system utilizing passive infrared detectors positioned on top, below, and in the pit area of the elevator car, coupled with a local processor, to detect the presence of persons

Methodology Applied

Scientific EffectInfrared radiation detection: Infrared Radiation

Data Source

PatentUS8556043B2Passive detection of persons in elevator hoistway

Publication Date: 2013.10.15 OTIS ELEVATOR CO

AI summary

Passive infrared detectors (20, 22, 24, 26, 28) carried by an elevator car (14) detect the presence of persons on top of or in the hoistway (12) below the elevator car (14). The passive infrared detectors (20, 22, 24, 26, 28) can also be used to detect open landing doors with no elevator present.