Elevator Electromagnetic Brake with Partial Spring-Force Offset

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Solution Overview

Problem

Existing passenger conveyer systems, such as elevators, struggle to control deceleration rates during braking, often resulting in uncomfortable high deceleration rates that affect ride quality.

Innovation Solution

An electromagnetic brake system with primary and secondary electromagnets is used to control deceleration rates by partially offsetting the spring bias force, utilizing adjustable current levels in the secondary coil to produce a magnetic field that reduces the deceleration rate without fully disengaging the brake.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the brake system applies full spring bias force to stop the elevator car, then the stopping reliability is improved, but the deceleration rate becomes excessively high causing discomfort to passengers

Engineering Contradiction:

Improvestopping reliabilityVSAvoiddeceleration rate

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The brake system is segmented into two independent electromagnet circuits: a primary electromagnet for full braking control and a secondary electromagnet for deceleration modulation. This segmentation allows the system to apply different levels of braking force independently, enabling reliable stopping while reducing harmful deceleration rates through the secondary electromagnet's partial offset of spring bias force.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system changes the magnetic field parameter by using two electromagnets with different current levels. The primary electromagnet operates at full current for reliable stopping, while the secondary electromagnet operates at a lower current level to provide a partial offset force, thereby controlling the deceleration rate and reducing passenger discomfort during braking.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If the electromagnet is activated to offset the spring bias force, then the deceleration rate is reduced improving ride quality, but the braking effectiveness may be compromised

Engineering Contradiction:

Improvedeceleration rateVSAvoidbraking effectiveness

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The secondary electromagnet applies a partial offset force rather than fully counteracting the spring bias force. By providing only a partial offset (enough to reduce deceleration to acceptable levels but not eliminate braking), the system maintains braking effectiveness while improving ride quality, avoiding the extremes of full offset or no offset.

Inventive Principle:

Principle #16Partial or excessive action

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 system effectively manages deceleration rates, providing comfortable braking by partially offsetting the spring force, thereby enhancing ride quality and reducing harsh deceleration sensations.

Implementation Method 1

an electromagnet selectively activated in response to a command from the controller to produce a magnetic field attracting the plate in a second direction opposite the first direction to partially offset the bias force of the spring

Methodology Applied

Scientific EffectElectromagnetism: Electromagnet

Data Source

PatentEP3822208B1Electromagnetic brake configured to slow deceleration rate of an elevator during braking

Publication Date: 2025.12.24 OTIS ELEVATOR CO

Figure 1~2
Figure 3

AI summary

This disclosure relates to an electromagnetic brake (22) configured to slow a deceleration rate of a passenger conveyer, such as an elevator car, during braking. In particular, this disclosure relates to a passenger conveyer system including the electromagnetic brake (22) and a corresponding method. An example system includes a controller (28) and an electromagnetic brake (22). The electromagnetic brake (22) includes a disc (32) configured to interface with a drive shaft, a spring (38), and a plate (36) biased in a first direction (Di) into engagement with the disc (32) by a bias force of the spring (38). The electromagnetic brake (22) further includes an electromagnet (42) selectively activated in response to a command from the controller (28) to produce a magnetic field attracting the plate (36) in a second direction (D2) opposite the first direction (Di) to partially offset the bias force of the spring (38). Further, when the electromagnet (42) is activated, the plate (36) engages the disc (32).