Elevator Drive Machine Engine Braking for Smooth Emergency Stops

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Solution Overview

Problem

Existing passenger transport systems, such as elevators, experience uncomfortable and inefficient emergency stops due to high braking deceleration, which can exceed 1g, and are hindered by delays in braking force generation and system-related delays, leading to inadequate braking performance.

Innovation Solution

A braking method that maintains the drive machine connected to the power supply during emergency stops, transitioning from engine braking to mechanical braking based on detected braking effects, allowing for a smoother transition and optimizing braking power to minimize braking distance and maximize comfort.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If the service brake is activated immediately during an emergency stop, then the braking distance is reduced, but the braking deceleration becomes excessively high causing user discomfort and exceeding 1g

Engineering Contradiction:

Improvebraking distanceVSAvoidbraking deceleration

Core Design Contradiction:

Loss of timeVSObject-affected harmful factors

Solution Approach 1:

The drive machine is switched to engine braking mode before the service brake is fully activated. This preliminary braking action reduces the speed of the passenger transport system gradually, so that when the service brake engages, the remaining speed is lower, resulting in reduced braking deceleration and improved user comfort while still achieving adequate braking distance.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Engine braking acts as a cushioning mechanism that absorbs kinetic energy before the mechanical service brake engages. By maintaining the drive machine connection during the transition phase, the system creates a smooth deceleration profile that cushions the impact of service brake activation, preventing sudden high deceleration forces on passengers.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Speed

If the drive machine is disconnected from the supply network simultaneously with service brake activation, then the braking response time is reduced, but system delays in switching deteriorate braking performance

Engineering Contradiction:

Improvebraking response speedVSAvoidbraking performance

Core Design Contradiction:

SpeedVSLoss of time

Solution Approach 1:

The drive machine is switched to engine braking mode as a preliminary action before being completely disconnected from the supply network. This allows the braking process to begin immediately using the drive machine's electromagnetic torque, while the disconnection process can proceed without compromising braking performance. The engine braking phase ensures braking action starts instantly, eliminating system switching delays.

Inventive Principle:

Principle #10Preliminary action

3Speed

If a non-adjustable part of braking force is provided directly, then the braking force generation speed is increased, but the braking effect is insufficient when emergency braking is initiated

Engineering Contradiction:

Improvebraking force generation speedVSAvoidbraking effect

Core Design Contradiction:

SpeedVSForce

Solution Approach 1:

The braking system dynamically adjusts the contribution of engine braking versus service brake based on real-time conditions. The drive machine remains connected during the emergency stop sequence, allowing the control system to optimize the braking force distribution dynamically. Engine braking provides immediate adjustable braking force, while the service brake supplements it, ensuring both rapid response and sufficient total braking effect.

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

This approach reduces the braking distance, enhances user comfort, and ensures safety by controlling the braking torque to prevent excessive loads, while protecting the brake lining and maintaining system efficiency.

Implementation Method 1

the drive machine of the passenger transport system is controlled in an engine braking mode

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a service brake is activated and an emergency stop is initiated

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentEP3008007B1Braking methods for a passenger transport installation, brake control for performing the brake method and passenger transport installation with a brake control

Publication Date: 2017.03.29 INVENTIO AG

AI summary

The invention relates to a braking method for a passenger transport system (1) which is designed as an elevator, escalator or moving walkway. Upon the occurrence of a technical problem on the passenger transport system (1), a service brake (15) of the passenger transport system (10) is activated by means of an activation signal and an emergency stop is initiated. In addition to activation of the service brake (15), the activation signal is supplied directly to a brake control (3) of the passenger transport system (1) such that, upon the occurrence of the activation signal by means of the brake control (3) a drive machine (9) of the passenger transport system (1) is actuated in a motor brake operating mode. The drive machine (9) is not switched by the brake control (3) to a condition free of braking torque until a braking effect of the service brake (15) is detected on moving components (4, 5, 6, 7, 10, 22) of the passenger transport system (1) and has been transmitted to the brake control (3).