Electromagnetic Brake Assembly With Conical Interface for Quiet Holding Torque

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Solution Overview

Problem

Conventional braking mechanisms in powered mobility assistance devices are noisy, bulky, and inefficient, with limited holding torque, making them unsuitable for individuals with impairments short of complete paralysis, such as those using KAFO and HKAFO devices.

Innovation Solution

A low-profile, quiet, and high-torque electromagnetic brake assembly with an integrated solenoid coil and friction components, where a ferrous armature interacts with a rotating member to provide controlled braking, utilizing a conical interface and O-rings for enhanced friction and wear performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If conventional braking mechanisms are used in powered mobility assistance devices, then the devices can provide holding torque during swing phase, but the mechanisms are noisy, bulky, and have limited holding torque capacity

Engineering Contradiction:

Improveholding torqueVSAvoidnoise

Core Design Contradiction:

ForceVSObject-generated harmful factors

Solution Approach 1:

The patent replaces conventional mechanical braking mechanisms with an electromagnetic brake assembly that uses a solenoid coil to generate magnetic force. This substitution eliminates the noisy mechanical engagement and disengagement of traditional brakes while providing sufficient holding torque through electromagnetic attraction between the armature and brake stator.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The brake assembly is integrated within the motor assembly, with the brake stator, armature, and solenoid coil nested within the motor housing. The brake components are positioned concentrically around the motor shaft, allowing the brake to be housed within the same space as the motor, thereby reducing overall device bulk.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Force

If conventional braking mechanisms are used, then holding torque can be provided, but the mechanisms are bulky and take up excessive space

Engineering Contradiction:

Improveholding torqueVSAvoidbrake assembly volume

Core Design Contradiction:

ForceVSVolume of moving object

Solution Approach 1:

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The brake assembly and motor assembly are merged into a single integrated unit. The brake stator is positioned within the motor housing, and the armature is coupled to the motor shaft, combining the functions of motor and brake into one compact assembly that reduces the overall volume required in the mobility device.

Inventive Principle:

Principle #5Merging (Combining)

3Force

If electromagnetic brake assembly is used, then holding torque and motor duty cycle reduction are achieved, but electrical power consumption increases

Engineering Contradiction:

Improveholding torqueVSAvoidelectrical power input

Core Design Contradiction:

ForceVSUse of energy by moving object

Solution Approach 1:

The solenoid coil is activated only during the swing phase of gait when holding torque is required to prevent knee buckling. During the stance phase, when the foot is on the ground and the knee is naturally stable, the coil is de-energized. This periodic activation reduces overall electrical power consumption while providing holding torque when needed.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The control system automatically manages the brake activation based on gait phase detection, eliminating the need for continuous manual control. The system self-regulates power consumption by activating the brake only when biomechanical conditions indicate the need for holding torque, optimizing energy efficiency.

Inventive Principle:

Principle #25Self-service

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 brake assembly provides effective, controlled holding torque with minimal electrical power input, engaging and disengaging quietly and reducing the duty cycle of electric motors, thus enhancing mobility assistance for individuals with lesser impairments while optimizing battery life.

Implementation Method 1

When the solenoid coil is energized, the armature translationally moves from the disengaged position to the engaged position

Methodology Applied

Scientific EffectElectromagnetism: Electromagnet

Implementation Method 2

the braking face of the armature interacts with the mating surface of the rotating member to apply a braking force to the rotating member

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentEP3975967B1Electromagnetic brake for powered mobility assistance device

Publication Date: 2023.06.28 EKSO BIONICS HLDG INC

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AI summary

An electromagnetic brake assembly includes a solenoid coil; a fixed ferrous brake stator; a ferrous armature having a braking face, wherein the armature is moveable in a translation direction relative to the brake stator between a disengaged position and an engaged position; and a rotating member including a mating surface and that rotates relative to the armature when the armature is in the disengaged position. When the solenoid coil is energized, the armature translationally moves from the disengaged position to the engaged position, and in the engaged position the braking face of the armature interacts with the mating surface of the rotating member to apply a braking force to the rotating member. The braking face and the mating surface may form a conical interface, and the conical interface further may include a friction O-ring positioned within a slot that permits the O-ring to roll along the braking interface when the armature moves between the disengaged position and the engaged position.