Retractable Elevator Apron Mechanism for Shallow Hoistways

Solution Overview

Problem

Elevator aprons hitting the bottom of the hoistway in elevator systems with no or shallow pits cause noise and wear, necessitating a retractable solution.

Innovation Solution

A retractable apron mechanism that moves between extended and retracted positions, activated by the elevator's movement, using mechanical components like rollers and pulleys to prevent contact with the hoistway bottom.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the apron is made retractable to prevent hitting the hoistway bottom, then noise and wear are reduced, but the device complexity increases due to additional retraction mechanisms

Engineering Contradiction:

Improvenoise and wear of apronVSAvoidretraction mechanism complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The apron is retracted in advance before the elevator car reaches the bottom of the hoistway. The retraction mechanism is activated by the downward movement of the elevator car itself, which pulls the apron upward through mechanical linkages (ropes, pulleys, or cranes) before contact with the hoistway bottom can occur. This preliminary action prevents the harmful impact while using the existing motion of the elevator car to drive the retraction.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The retraction mechanism utilizes the gravitational force and the downward movement of the elevator car to automatically retract the apron. The system does not require external power sources or complex control systems - the weight of the apron and the motion of the elevator car itself provide the energy needed for retraction. The mechanism serves itself by converting the downward motion into upward retraction through mechanical advantage.

Inventive Principle:

Principle #25Self-service

2Reliability

If the apron is extended to close the gap between elevator car and floor, then safety is improved, but the risk of hitting the hoistway bottom increases in shallow pit configurations

Engineering Contradiction:

Improvesafety of elevator carVSAvoidcontact with hoistway bottom

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The apron transitions from a static structure to a dynamic one that can change its position based on the elevator car's location. When the elevator car is positioned above the bottom of the hoistway, the apron extends downward to close the gap and ensure safety. When approaching the bottom, the apron dynamically retracts to avoid contact. This dynamic adjustment allows the system to maintain safety while eliminating the harmful contact risk.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The apron is retracted in advance before the elevator car reaches the bottom of the hoistway. The retraction mechanism is activated by the downward movement of the elevator car itself, which pulls the apron upward through mechanical linkages (ropes, pulleys, or cranes) before contact with the hoistway bottom can occur. This preliminary action prevents the harmful impact while using the existing motion of the elevator car to drive the retraction.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20250353705A1Elevator car with retractable apron and elevator system comprising such an elevator car

Publication Date: 2025.11.20 OTIS ELEVATOR CO

AI summary

An elevator car (6) includes a retractable apron (12), which is movable between an extended position and a retracted position, and a retraction mechanism (14), which is configured for retracting the apron (12) from the extended position into the retracted position when the elevator car (6) approaches the bottom (4a) of a hoistway (4), so that the apron (12) does not contact the bottom (4a) of the hoistway (4).