Input-Side Mechanical Brake for Compact Power Tool Drivetrains

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Solution Overview

Problem

Existing active injury mitigation systems for mobile power tools are cumbersome and weighty, complicating their operation due to the need for additional space and weight, which hinders manual handling and increases the risk of injury from implement contact with the user's body.

Innovation Solution

A compact and lightweight drivetrain with a brake unit integrated into the gear stage, where the brake unit is drivingly coupled to the input side, allowing it to decelerate or stop the implement holder with a reduced torque, thus minimizing the weight and size requirements, and enabling reliable operation with various types of implements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an active injury mitigation system (brake unit) is added to the mobile power tool, then the safety and injury prevention capability is improved, but the weight and space requirements increase, complicating the operation and handling of the tool

Engineering Contradiction:
Improveinjury prevention capabilityVSAvoidweight of power tool
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The brake unit is integrated into the gear stage by drivingly coupling it to the input side of the gear stage. This merging of the brake function with the existing gear stage structure allows the brake unit to benefit from the torque reduction provided by the gear stage, enabling a more compact and lighter brake system while maintaining effective injury prevention capability

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If an active injury mitigation system (brake unit) is added to the mobile power tool, then the safety and injury prevention capability is improved, but the space requirements increase, complicating the operation and handling of the tool

Engineering Contradiction:
Improveinjury prevention capabilityVSAvoidspace occupied by brake unit
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The brake unit is merged with the gear stage structure through driving coupling at the input side. This integration allows the brake unit to be positioned within or alongside the existing gear stage components, minimizing additional space requirements while providing effective injury mitigation

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If a brake unit is drivingly coupled to the output side of the gear stage, then the braking effectiveness on the implement is improved, but the torque requirements and resulting brake unit size increase

Engineering Contradiction:
Improvebraking effectivenessVSAvoidbrake unit size
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

Instead of coupling the brake unit to the output side of the gear stage (where high torque is present), the brake unit is invertedly coupled to the input side of the gear stage (where torque is reduced). This inversion of the typical braking approach allows the brake unit to operate with lower torque requirements, resulting in a more compact and simpler brake system while maintaining effective braking capability through the mechanical advantage of the gear stage

Inventive Principle:
Principle #13The other way round (Inversion)

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 and lightweight brake system that effectively mitigates injuries by decelerating or stopping the implement without complicating the operation of the mobile power tool, maintaining ease of handling and allowing for versatile implement compatibility.

Implementation Method 1

the brake unit is configured to decelerate or stop the movement of the implement holder in an engaged state of the brake unit

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP4527558A1Drivetrain for a mobile power tool, mobile power tool and use of a mechanical brake
Publication Date: 2025.03.26 FESTOOL GMBH
  • EP4527558A1 patent drawingFigure 1~2
  • EP4527558A1 patent drawingFigure 3~4
  • EP4527558A1 patent drawingFigure 5~6

AI summary

A drivetrain (16) for a mobile power tool is shown. The drivetrain (16) comprises a gear stage (28) having an input side and an output side. The drivetrain (16) also comprises an implement holder (40) configured to be coupled to an implement (20) and drivingly coupled to the output side of the gear stage (28). Moreover, the drivetrain (16) comprises a brake unit (42) drivingly coupled to the input side of the gear stage (28) and configured to permit a movement of the implement holder (40) in a disengaged state of the brake unit (42) and to decelerate or stop the movement of the implement holder (40) in an engaged state of the brake unit (42). Furthermore, a mobile power tool comprising such a drivetrain (16) is presented. Additionally, a use of a mechanical brake at an input side of a gear stage (28) of a drivetrain (16) for a mobile power tool is explained.