Elevator Brake Control Using Solid State Switches

Solution Overview

Problem

Elevator system designers face challenges in reducing costs and space requirements due to the use of expensive and space-consuming force guided relays for controlling elevator brake power supply, which are necessary for monitoring relay actuation in a fail-safe manner.

Innovation Solution

A relay switch associated with a safety chain monitors elevator door conditions, with a solid state switch in series controlling power to the elevator brake, allowing power only when all doors are closed, and preventing power when at least one door is open, using a driver to manage the solid state switch and eliminate the need for force guided relays.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If force guided relays are used to control elevator brake power supply with monitoring capability, then reliability is improved, but cost and device complexity increase

Engineering Contradiction:

Improvemonitoring capabilityVSAvoidrelay structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical force-guided relay system with a solid state switch (semiconductor device) controlled by a driver circuit. The solid state switch eliminates the need for mechanical relay contacts and force guidance mechanisms while providing the same monitoring function through electronic control. The driver circuit receives input from the safety chain and controls the solid state switch accordingly, achieving reliable monitoring without mechanical complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If force guided relays are used to control elevator brake power supply, then reliability is improved, but space requirements increase

Engineering Contradiction:

Improvemonitoring capabilityVSAvoidcircuit board space

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent replaces the mechanical force-guided relay system with a solid state switch (semiconductor device) controlled by a driver circuit. The solid state switch eliminates the need for mechanical relay contacts and force guidance mechanisms while providing the same monitoring function through electronic control. The driver circuit receives input from the safety chain and controls the solid state switch accordingly, achieving reliable monitoring without mechanical complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If force guided relays are used to control elevator brake power supply, then reliability is improved, but cost increases

Engineering Contradiction:

Improvemonitoring capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces the mechanical force-guided relay system with a solid state switch (semiconductor device) controlled by a driver circuit. The solid state switch eliminates the need for mechanical relay contacts and force guidance mechanisms while providing the same monitoring function through electronic control. The driver circuit receives input from the safety chain and controls the solid state switch accordingly, achieving reliable monitoring without mechanical complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP2763925B1Elevator brake control

Publication Date: 2020.11.25 OTIS ELEVATOR CO

Figure 1

AI summary

An exemplary elevator brake control device includes a relay switch that is associated with a safety chain configured to monitor at least one condition of a selected elevator system component. The relay switch is selectively closed to allow power supply to an electrically activated elevator brake component responsive to the monitored condition having a first status. The relay switch is selectively opened to prevent power supply to the brake component responsive to the monitored condition having a second, different status. A solid state switch is in series with the relay switch between the relay switch and the brake component. A driver selectively controls the solid state switch to selectively allow power to be supplied to the brake component only if the relay switch is closed and the monitored condition has the first status.