Intermittent Elevator Brake Torque Detection

Solution Overview

Problem

Existing braking torque detection methods for elevator brakes face challenges in accuracy and overheating of frequency converters due to continuous output of large torque currents, which affects the reliability and precision of the detection process.

Innovation Solution

A method and system that implement intermittent output of detection torques, with a first detection torque being applied only when specific conditions are met and a second detection torque being applied after a cooling period, to prevent overheating and ensure accurate braking torque inspection, utilizing a controller and frequency converter to manage the output of detection torques.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If continuous large torque currents are output for braking torque detection, then detection accuracy is improved, but frequency converter overheating occurs

Engineering Contradiction:

Improvebraking torque detection accuracyVSAvoidfrequency converter temperature

Core Design Contradiction:

Measurement precisionVSTemperature

Solution Approach 1:

The patent implements periodic action by alternating between first and second detection torques with intermittent time periods in between. The first detection torque is applied for a first detection period, then an intermittent time period follows, and subsequently the second detection torque is applied for a second detection period. This periodic alternation allows the frequency converter to cool down during intermittent periods while still performing repeated detections, thus resolving the contradiction between detection accuracy and overheating.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent applies dynamics by making the detection torque magnitude variable rather than constant. The system dynamically switches between two different detection torque levels (first and second detection torques) based on the detection phase. The second detection torque is specifically designed to be smaller than the first, allowing adaptive adjustment of power output to prevent overheating while maintaining detection capability.

Inventive Principle:

Principle #15Dynamics

2Reliability

If first detection torque is applied continuously, then detection coverage is improved, but system reliability deteriorates due to overheating risks

Engineering Contradiction:

Improvedetection system reliabilityVSAvoidfrequency converter overheating

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent implements periodic action by alternating between first and second detection torques with intermittent time periods in between. The first detection torque is applied for a first detection period, then an intermittent time period follows, and subsequently the second detection torque is applied for a second detection period. This periodic alternation allows the frequency converter to cool down during intermittent periods while still performing repeated detections, thus resolving the contradiction between detection accuracy and overheating.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent applies beforehand cushioning by introducing intermittent time periods between consecutive detection torque applications. These intermittent periods serve as preventive cooling intervals that cushion against the accumulation of heat in the frequency converter before overheating can occur, thereby maintaining system reliability during continuous detection operations.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Temperature

If second detection torque (smaller than first) is used, then overheating is reduced, but detection precision may be compromised

Engineering Contradiction:

Improvefrequency converter temperatureVSAvoidbraking torque detection accuracy

Core Design Contradiction:

TemperatureVSMeasurement precision

Solution Approach 1:

The patent applies segmentation by dividing the detection process into two distinct phases with different torque levels. The first detection phase uses a first detection torque for initial assessment, while the second detection phase uses a smaller second detection torque for follow-up verification. This segmentation allows the system to balance between applying sufficient torque for accurate detection and using reduced torque to prevent overheating during repeated detections.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies dynamics by making the detection torque magnitude variable rather than constant. The system dynamically switches between two different detection torque levels (first and second detection torques) based on the detection phase. The second detection torque is specifically designed to be smaller than the first, allowing adaptive adjustment of power output to prevent overheating while maintaining detection capability.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentEP3434636B1Brake torque detection for elevator brake

Publication Date: 2023.08.30 OTIS ELEVATOR CO

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AI summary

The present invention relates to braking torque detection for an elevator brake (140) and belongs to the technical field of elevators. A braking torque detection method for an elevator brake (140) according to the present invention comprises the following steps (S320,S410):a drive motor (130) outputting a first detection torque (T1,T2) for a first brake torque inspection; the drive motor (130) stopping output of the detection torque (T1,T2) in intermittent time periods when it is determined that a second brake torque inspection is required according to a result of the first brake torque inspection;and the drive motor (130) outputting a second detection torque (T1,T2) for the second brake torque inspection. The present invention can avoid overheating of a frequency converter (120) in a continuous braking torque detection process and achieves good braking torque detection accuracy.