Integrated Motor Braking Coil for Simpler Power Tool Motors

Solution Overview

Problem

Braking resistors and heat sinks in power tool motors are costly and complicate the form factor, increasing manufacturing costs and complexity.

Innovation Solution

Incorporating a motor braking coil wound around the stator or stator windings, which dissipates heat through the stator or airflow, eliminating the need for additional heat sinks and resistors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If braking resistors and heat sinks are added outside the motor, then motor braking capability is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improvemotor braking capabilityVSAvoidform factor complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The braking coil is merged with the motor stator structure. The coil is wound around the stator core or stator teeth, integrating the braking function directly into the motor assembly. This eliminates the need for separate external braking resistors and heat sinks, reducing device complexity while maintaining braking capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The stator structure serves dual functions: as the motor's magnetic core for motor operation and as the mounting structure for the braking coil. The stator teeth and windings provide both motor function and braking resistance, making the motor assembly multi-functional and reducing overall component count.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If braking resistors and heat sinks are added outside the motor, then motor braking capability is improved, but manufacturing cost increases

Engineering Contradiction:

Improvemotor braking capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The braking coil is manufactured as part of the motor assembly process. The coil is wound around the stator during motor manufacturing, eliminating the need for separate procurement and assembly of external braking components. This integration reduces manufacturing steps and overall cost.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The stator structure serves dual functions: as the motor's magnetic core for motor operation and as the mounting structure for the braking coil. The stator teeth and windings provide both motor function and braking resistance, making the motor assembly multi-functional and reducing overall component count.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If braking resistors are placed outside the motor, then braking function is achieved, but heat dissipation requires additional heat sink components

Engineering Contradiction:

Improvebraking functionVSAvoidcomponent count

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The braking coil is merged with the motor stator structure. The coil is wound around the stator core or stator teeth, integrating the braking function directly into the motor assembly. This eliminates the need for separate external braking resistors and heat sinks, reducing device complexity while maintaining braking capability.

Inventive Principle:

Principle #5Merging (Combining)

4Temperature

If the motor braking coil is wound around the stator, then heat dissipation is improved through the stator, but the stator structure must handle additional thermal load

Engineering Contradiction:

Improveheat dissipation capabilityVSAvoidthermal stress on stator

Core Design Contradiction:

TemperatureVSStress or pressure

Solution Approach 1:

The stator structure serves itself by providing both magnetic function for motor operation and thermal dissipation path for the braking coil. The stator's inherent thermal mass and surface area are utilized to dissipate braking heat, eliminating the need for separate heat sink components.

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

Reduces manufacturing costs and simplifies the power tool's form factor by distributing braking resistance over a larger area, enhancing heat dissipation and reducing component count.

Implementation Method 1

The motor braking coil and the braking switch are connected between the power source and the plurality of switching elements... connect the motor braking coil to the motor to brake the motor

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

The stator of the motor absorbs the heat from the motor braking coil

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

the heat generated by the motor braking coil is dissipated by an airflow generated by a fan of the motor

Methodology Applied

Scientific EffectConvection: Convection

Data Source

PatentUS12506422B2Motor braking coil for a power tool

Publication Date: 2025.12.23 MILWAUKEE ELECTRIC TOOL CORP

AI summary

Method and power tool for braking a motor of the power tool. One embodiment provides a method for braking a motor of a power tool. The method includes operating, using a motor controller of the power tool, the motor in accordance with a user input. The method also includes detecting, using the motor controller, a braking event of the power tool and connecting, using a braking switch, a motor braking coil to the motor to brake the motor in response to detecting the braking event of the power tool. The method further includes cooling, using a component of the motor, the motor braking coil.