Elevator Governor Rope Tensioning with Spring Failure Detection

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Solution Overview

Problem

Existing rope tensioning devices for elevator overspeed governors are complex, require guidance for springs, and pose safety risks due to unreliable force generation by extension springs, while compression springs lack pretension force.

Innovation Solution

A rope tensioning device using two parallel extension springs with a tiltable connecting member and a detection mechanism to activate a switch when the springs fail, ensuring immediate detection of reduced tension.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If extension springs are used for rope tensioning, then the device is simpler and more compact, but safety is compromised because the spring may fail without generating sufficient force

Engineering Contradiction:

Improvestructure complexityVSAvoidsafety

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The tensioning device is divided into separate functional modules: the extension spring assembly for tensioning, the tiltable connecting member for movement detection, and the switch mechanism for safety signaling. This segmentation allows each component to perform its specific function reliably while maintaining overall system simplicity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A tiltable connecting member acts as an intermediary between the extension spring and the switch. When the spring fails or loses tension, the connecting member tilts and mechanically activates the switch, providing reliable failure detection without requiring complex electronic sensors or additional actuation mechanisms.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If compression springs are used for rope tensioning, then safety is improved through reliable force generation, but the device becomes more complex requiring guidance mechanisms

Engineering Contradiction:

Improveforce generation reliabilityVSAvoidguidance structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Instead of using compression springs that require complex guidance mechanisms to maintain their orientation and force generation, the patent inverts the approach by using extension springs. The extension springs naturally extend in a linear fashion without requiring complex guidance, while still providing reliable tensioning force through their elastic properties.

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If compression springs are used for rope tensioning, then force generation is reliable, but pretension force cannot be produced

Engineering Contradiction:

Improveforce generationVSAvoidpretension capability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The extension spring's elastic properties allow it to be pre-loaded during manufacturing to provide pretension force. By changing the physical parameters of the spring (such as wire diameter, coil density, and length), the pretension force can be precisely controlled and adjusted to match the specific requirements of the elevator governor system, while maintaining reliable force generation during operation.

Inventive Principle:

Principle #35Parameter changes

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 solution provides a safe, simpler, and compact rope tensioning system that reliably detects spring failure, immediately interrupting elevator operation to ensure safety.

Implementation Method 1

two extension springs arranged in parallel; a first connecting member mounted on the fixed support member and a second connecting member mounted on the lever arm, each extension spring having one end connected to the first connecting member and the other one to the second connecting member

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

at least one of the first and second connecting members is mounted so as to be tiltable around a hinge axis, the tiltable connecting member being held in a predetermined working position by the two extension springs

Methodology Applied

Scientific EffectRotation:

Implementation Method 3

means for detecting a tilt of the tiltable connecting member beyond a predetermined angle with respect to its working position. According to one embodiment, the means for detecting comprises a switch which is activated when the tiltable connecting member is tilted beyond the predetermined angle

Methodology Applied

Scientific EffectMechanical contact detection:

Data Source

PatentEP4469380B1Rope tensioning device for an overspeed governor of an elevator and an elevator comprising such a rope tensioning device

Publication Date: 2026.01.14 WITTUR HLDG GMBH

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Figure 3~4
Figure 5~6

AI summary

A rope tensioning device (1) for an overspeed governor of an elevator, comprising: a pulley (2); a lever arm (3) hinged to the pulley (2); a fixed support member (4), to which one end (3a) of the lever arm (3) is hinged; two extension springs (5) arranged in parallel; a first connecting member (6) mounted on the fixed support member (4) and a second connecting member (7) mounted on the lever arm (3), each extension spring (5) having one end connected to the first connecting member (6) and the other one to the second connecting member (7), at least one of the first and second connecting members (6, 7) is mounted so as to be tiltable around a hinge axis (X), said at least one tiltable connecting member (6, 7) being held in a predetermined working position by the two extension springs (5); means for detecting (8) a tilt of said at least one tiltable connecting member (6, 7) beyond a predetermined angle with respect to its working position.