Elevator Pit Ladder Lockout Using Presence Sensors

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Solution Overview

Problem

Elevator pits are often too small for safe maintenance, posing risks to personnel, and existing safety measures are inadequate to ensure the elevator remains non-operational during maintenance procedures.

Innovation Solution

A safety device with sensors along the elevator pit ladder path generates a signal to lock out the elevator's operational state, ensuring it remains non-functional until a reset is activated, using a lockout mechanism and reset circuit to manage the machine's state.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If elevator pits are made as small as possible to save space, then space utilization is improved, but safety for personnel working in the pit deteriorates

Engineering Contradiction:

Improveelevator pit areaVSAvoidsafety risk to personnel

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The sensor detects the presence of personnel on the pit ladder before they enter the hazardous pit region, and the lockout mechanism is activated in advance to prevent elevator movement. This preliminary safety action is taken before the personnel are actually in danger, resolving the contradiction by enabling safe work in compact pits through proactive protection.

Inventive Principle:

Principle #10Preliminary action

2Object-affected harmful factors

If a lockout mechanism is implemented to prevent elevator movement during maintenance, then safety is improved, but device complexity increases

Engineering Contradiction:

Improvesafety risk to personnelVSAvoidsafety device complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The sensor continuously monitors the pit ladder area and provides feedback to the lockout mechanism. When personnel are detected, the system automatically activates the lockout; when personnel leave, the system can be reset. This automated feedback loop improves safety while keeping the device complexity manageable through intelligent control rather than mechanical complexity.

Inventive Principle:

Principle #23Feedback

3Object-affected harmful factors

If sensors are installed along the pit ladder path to detect personnel, then safety monitoring is improved, but device complexity and cost increase

Engineering Contradiction:

Improvesafety monitoring capabilityVSAvoidsensor system complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

Instead of installing sensors throughout the entire pit or using complex multi-sensor arrays, the invention places a simple presence-detecting sensor at the critical location where personnel enter the pit via the ladder. This localized sensing approach provides adequate safety monitoring with minimal added complexity, addressing the contradiction by focusing safety resources on the most critical hazard zone.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS20220048731A1Safety lockout on paths to regions of heightened risk

Publication Date: 2022.02.17 ELEVATOR IND WORK PRESERVATION FUND

AI summary

A safety device for a path that is traversed to enter a region in which danger to an individual is heightened due to operation of a machine includes at least one sensor installed along the path so as to detect the individual thereat, which compels the sensor to generate a signal. A lockout mechanism is deployed that compels the machine into a non-operational state in response to receiving the signal from the sensor. The lockout mechanism ensures the machine remains in the non-operational state when the signal from the sensor is removed therefrom. A reset circuit is deployed that, in response to activation thereof, compels the lockout mechanism to allow the machine into the operational state from the non-operational state.