Magnetic Field Braking Device for Portable Power Tools

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Solution Overview

Problem

Existing power tool braking systems face challenges in efficiently and frictionlessly reducing the speed of rotating components, particularly in portable machine tools, where space is limited and reliable, friction-free braking is essential for safety and efficiency.

Innovation Solution

A power tool braking device incorporating a magnetic brake unit, integrated into an angular gear system, which uses a mechanical activation unit to initiate a relative movement that changes the magnetic field parameters, allowing for frictionless braking of the machining tool, independent of the electric motor's magnetic field, and can be designed as an eddy current or hysteresis brake for enhanced performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a friction braking unit is used to reduce the speed of rotating components, then the braking force is reliable and controllable, but frictional forces cause wear, heat generation, and energy loss

Engineering Contradiction:
Improvebraking force reliabilityVSAvoidfrictional forces and wear
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the mechanical friction braking system with an electromagnetic braking system. The electromagnetic brake uses magnetic fields to generate braking force through electromagnetic interaction between the stator and rotor, eliminating the need for friction-based braking mechanisms. This substitution maintains reliable and controllable braking force while eliminating frictional wear, heat generation, and energy loss associated with mechanical friction brakes.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental parameter of braking mechanism from mechanical friction to electromagnetic force. By using electromagnetic fields instead of physical contact, the system achieves the same braking function through a different physical principle, thereby eliminating the harmful effects of friction while maintaining braking reliability and controllability through electromagnetic parameter control.

Inventive Principle:
Principle #35Parameter changes

2Object-generated harmful factors

If a magnetic field braking unit is used to achieve frictionless braking, then frictional wear and heat generation are reduced, but the device complexity increases due to additional electromagnetic components

Engineering Contradiction:
Improvefrictional wear and heatVSAvoidelectromagnetic braking components
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges the electromagnetic braking components (stator and rotor) directly into the output unit structure. The braking elements are integrated with the existing mechanical components, allowing the electromagnetic braking system to be incorporated without adding separate, complex assemblies. This integration reduces device complexity while maintaining the frictionless braking advantage.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The electromagnetic braking unit is designed to serve multiple functions: it provides frictionless braking, can be integrated into the output unit structure, and works independently of the drive system. This multi-functionality reduces the need for additional specialized components, thereby simplifying the overall device complexity while achieving the desired frictionless braking performance.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Volume of moving object

If the magnetic field braking unit is integrated into the output unit, then installation space is saved, but the braking element arrangement becomes more constrained

Engineering Contradiction:
Improveinstallation spaceVSAvoidbraking element arrangement
Core Design Contradiction:
Volume of moving objectVSDevice complexity

Solution Approach 1:

The patent implements a nested arrangement where the braking elements (stator and rotor) are positioned concentrically around the output shaft. The stator is arranged on the output element and the rotor on the output shaft, creating a compact nested structure that maximizes space utilization. This nesting approach saves installation space while providing sufficient clearance for the magnetic field to function effectively.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent utilizes the radial dimension by arranging the braking elements in a concentric configuration around the output shaft. This dimensional arrangement allows the braking components to be compactly integrated into the existing output unit structure without interfering with the axial or tangential dimensions, thereby saving installation space while maintaining functional clearance.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 solution provides a compact, reliable, and efficient braking system that reduces the speed of rotating components without friction, ensuring safety and operational efficiency in portable power tools, with low error rates and the ability to be integrated into various machine tools, including angle grinders and drills.

Implementation Method 1

a magnetic field braking unit, which, by utilizing a magnetic field, reduces and/or limits the speed, in particular the rotational speed, of a moving component, especially a rotating component

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

designed as an eddy current or hysteresis brake

Methodology Applied
Scientific EffectEddy current damping: Eddy Current Damping

Implementation Method 3

change a characteristic parameter of a magnetic field of the magnetic field braking unit as a result of a relative movement

Methodology Applied
Scientific EffectMagnetic field interaction: Magnetic Field

Implementation Method 4

designed as an eddy current or hysteresis brake

Methodology Applied
Scientific EffectMagnetic hysteresis: Magnetic Hysteresis

Data Source

PatentEP2632650B1Power tool braking device
Publication Date: 2019.02.13 ROBERT BOSCH GMBH
  • EP2632650B1 patent drawingFigure 1
  • EP2632650B1 patent drawingFigure 2
  • EP2632650B1 patent drawingFigure 3

AI summary

The invention relates to a power tool braking device, in particular to a portable power tool braking device, for a portable power tool (12a; 12b; 12c) having at least one magnetic field braking unit (14a; 14b; 14c). It is proposed that the power tool braking device comprise at least one drive unit (42a; 42b; 42c) which has at least one drive element (44a, 46a; 44b, 46b; 44c, 46c), on which at least one braking element (18a, 24a; 18b, 24b; 18c, 24c) of the magnetic field braking unit (14a; 14b; 14c) is arranged.