Hydraulic Pull Rope Head Fixing Apparatus for Elevator Tension Balancing

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Solution Overview

Problem

Elevator systems using multiple pull ropes face challenges in maintaining balanced tensions, particularly with flat pull ropes, leading to wear on traction wheels and sheaves, increased maintenance, and reduced safety and performance due to unbalanced tensions.

Innovation Solution

A pull rope head fixing apparatus with hydraulic cylinders and pistons automatically balances tensions between multiple pull ropes by adjusting hydraulic forces and using an elastic component to absorb energy and reduce vibration, eliminating the need for manual tension adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If multiple pull ropes are used to lift the car simultaneously, then the lifting capacity and stability are improved, but the tensions of the pull ropes become unbalanced leading to wear on traction wheels and sheaves

Engineering Contradiction:
Improvelifting capacityVSAvoidtension balance
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The pull rope head fixing apparatus divides the tension balancing function into multiple independent hydraulic sub-cylinders, each handling one pull rope. This segmentation allows individual adjustment of each rope's tension while maintaining overall system balance, preventing wear on traction wheels and sheaves caused by unbalanced tensions.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The apparatus uses hydraulic cylinders with pistons to automatically adjust and balance the tensions of multiple pull ropes. The hydraulic system provides precise, continuous tension adjustment through fluid pressure control, ensuring reliable tension balance across all pull ropes while maintaining high lifting capacity.

Inventive Principle:
Principle #29Pneumatics and hydraulics

2Reliability

If manual tension adjustments are performed regularly, then the tension balance can be maintained, but the maintenance workload increases

Engineering Contradiction:
Improvetension balanceVSAvoidmaintenance workload
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The pull rope head fixing apparatus automatically balances tensions through its hydraulic system without requiring manual intervention. The device monitors and adjusts pull rope tensions in real-time, eliminating the need for regular manual tension adjustments and significantly reducing maintenance workload while maintaining reliable tension balance.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The apparatus incorporates automatic feedback control through its hydraulic piston system, which continuously monitors tension variations and makes real-time adjustments. This closed-loop control ensures tension balance is maintained automatically without manual intervention, reducing maintenance workload while preserving reliability.

Inventive Principle:
Principle #23Feedback

3Ease of operation

If hydraulic cylinders and pistons are used to adjust tensions automatically, then the maintenance workload is reduced, but the device complexity increases

Engineering Contradiction:
Improvemaintenance workloadVSAvoidapparatus structure
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The hydraulic cylinder assembly serves multiple functions simultaneously: it fixes the pull rope head, automatically balances tensions across multiple ropes, and provides vibration damping through the elastic component. This multi-functionality reduces the need for separate devices, thereby limiting the increase in overall device complexity while achieving automatic tension adjustment and reduced maintenance workload.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The apparatus combines the tension adjustment mechanism and the vibration damping function into a single integrated hydraulic cylinder assembly. By merging these functions, the design avoids the complexity of separate systems while achieving automatic tension balancing and reduced maintenance requirements.

Inventive Principle:
Principle #5Merging (Combining)

4Stability of the object's composition

If the pull ropes are flat ropes with greater width than thickness, then the lifting stability is improved, but the tension balance becomes more difficult to maintain

Engineering Contradiction:
Improvelifting stabilityVSAvoidtension balance
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The hydraulic piston system provides dynamic, real-time adjustment of pull rope tensions, adapting to variations in load distribution and rope characteristics. This dynamic control capability is particularly effective for flat ropes with greater width than thickness, as it continuously compensates for tension imbalances that arise from their unique mechanical properties, maintaining both lifting stability and tension balance.

Inventive Principle:
Principle #15Dynamics

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 apparatus maintains balanced tensions automatically, reducing maintenance workload, prolonging component lifespan, and improving operational safety and passenger experience by minimizing vibrations and noise.

Implementation Method 1

a hydraulic cylinder body configured to form a hydraulic cylinder; N first hydraulic sub-cylinders arranged in parallel on the hydraulic cylinder body and communicated with the hydraulic cylinder

Methodology Applied
Scientific EffectHydraulic pressure: Hydraulic Press

Implementation Method 2

an elastic component, at least one end of the elastic component receiving a hydraulic force of the hydraulic cylinder transmitted from the second piston while applying a bounce to the second piston

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3495305B1End-fastening apparatus for lifting rope and elevator system using thereof
Publication Date: 2021.12.01 OTIS ELEVATOR CO
  • EP3495305B1 patent drawingFigure 1
  • EP3495305B1 patent drawingFigure 2~3
  • EP3495305B1 patent drawingFigure 4

AI summary

The present invention provides a pull rope head fixing apparatus and an elevator system using the same, and belongs to the technical field of elevators. The pull rope head fixing apparatus of the present invention is configured to simultaneously fix rope heads of N pull ropes that are arranged in parallel, and includes: a hydraulic cylinder body configured to form a hydraulic cylinder; N first hydraulic sub-cylinders arranged in parallel on the hydraulic cylinder body and communicated with the hydraulic cylinder; and first pistons each disposed corresponding to each of the first hydraulic sub-cylinders. The pull rope head fixing apparatus of the present invention can automatically balance the tensions of multiple pull ropes fixed by it.