Elevator Hoisting Machine Idle Inspection via Counterweight Vibration

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional elevator systems fail to confirm the normal operation of the emergency stopper when the driving force of the hoisting machine is not large enough, due to high frictional forces or heavy elevator car weights, preventing the driving sheave from running idle.

Innovation Solution

The elevator system employs an elevator controller to drive the hoisting machine, exciting vertical natural vibration of the counterweight to allow the driving sheave to run idle, ensuring the emergency stopper's functionality can be confirmed even with insufficient driving force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the hoisting machine drives the elevator car downward at low speed to inspect the emergency stopper, then the emergency stopper operation can be confirmed when driving force is sufficient, but the driving sheave cannot run idle when frictional force is large or weight is heavy, preventing confirmation of normal operation

Engineering Contradiction:

Improveemergency stopper operation confirmationVSAvoiddriving force

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The patent applies mechanical vibration by exciting the counterweight to vibrate vertically at its natural frequency. This vibration causes the main rope to alternately tighten and loosen, creating periodic variations in tension that allow the driving sheave to run idle intermittently. The vibration frequency is controlled to match the natural frequency of the counterweight system, maximizing the amplitude of vibration and the effect on rope tension.

Inventive Principle:

Principle #18Mechanical vibration

Solution Approach 2:

The patent changes the operational parameters of the counterweight from a static state to a dynamically vibrating state. By controlling the hoisting machine to generate vibrations at the natural frequency of the counterweight, the system transforms the counterweight's motion state, which in turn causes periodic changes in main rope tension and enables the driving sheave to run idle during vibration cycles.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the driving force is increased to ensure the driving sheave runs idle during inspection, then the emergency stopper can be confirmed to operate normally, but the hoisting machine may cause the elevator car to descend too quickly or lose control

Engineering Contradiction:

Improveemergency stopper operation confirmationVSAvoidelevator car descent speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

Instead of increasing driving force continuously, the system uses mechanical vibration to create periodic variations in rope tension. This allows the driving sheave to run idle only during specific phases of the vibration cycle when tension is reduced, while maintaining controlled descent speed overall. The vibration approach enables emergency stopper confirmation without sustaining high driving forces that could cause uncontrolled descent.

Inventive Principle:

Principle #18Mechanical vibration

3Strength

If the frictional force between the main rope and driving sheave is increased to improve grip, then the elevator system has better holding capability, but the driving sheave cannot run idle during emergency stopper inspection

Engineering Contradiction:

Improveholding capabilityVSAvoidemergency stopper operation confirmation

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The vibration method temporarily reduces the effective frictional force by creating periodic slack in the main rope during counterweight vibration. This allows the driving sheave to run idle during inspection without permanently reducing the frictional grip needed for normal operation. The high frictional force is maintained during non-vibration periods for safe holding capability.

Inventive Principle:

Principle #18Mechanical vibration

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

This method enables the confirmation of the emergency stopper's normal operation by inducing vertical vibrations, allowing the driving sheave to run idle and ensuring the stopper's holding function is validated, even in cases where the driving force is insufficient.

Implementation Method 1

exciting vertical natural vibration of the counterweight

Methodology Applied

Scientific EffectNatural vibration: Resonance

Data Source

PatentUS10421639B2Elevator system and elevator inspection method for driving a hoisting machine while keeping an emergency stopper operational

Publication Date: 2019.09.24 MITSUBISHI ELECTRIC CORP

AI summary

In an elevator system, whether an emergency stopper thereof operates normally can be confirmed by letting a driving sheave run idle even in a case where the driving force of a hoisting machine is not large enough, the elevator system includes a main rope to suspend an elevator car and a counterweight, the emergency stopper to prevent the elevator car from dropping, the driving sheave, with the main rope wound around, to drive the main rope by a frictional force therebetween, the hoisting machine to rotate the driving sheave, and an elevator controller to drive the hoisting machine, wherein the elevator controller drives the hoisting machine, with the emergency stopper kept in operation, to let the driving sheave run idle by exciting vertical natural period vibration of the counterweight.