Handheld Power Tool Torque Control for Jam Release

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Solution Overview

Problem

Hand-held power tools often jam during screwing operations due to elastic deformation and wear, leading to complicated and time-consuming release processes, which can result in damage and require additional tools.

Innovation Solution

A method involving alternating torque directions, applying a first torque in one direction to tighten screws and a second torque in the opposite direction to release jams, utilizing a drive unit and clutch to reverse the rotation, thereby preventing tool damage and simplifying the screwing process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If continuous tightening torque is applied to screw in the screwing means, then the screwing means is tightened to desired depth or torque, but the handheld power tool clamps with the screwing means due to elastic deformation and wear

Engineering Contradiction:
Improvetightening torqueVSAvoidrelease process
Core Design Contradiction:
Manufacturing precisionVSEase of operation

Solution Approach 1:

The patent applies reverse rotation torque to the screwing means after tightening to release the clamping condition. By rotating the screwing means in the opposite direction, the elastic deformation and wear-induced clamping is reversed, allowing the screwing means to be easily removed from the handheld power tool without requiring additional tools or excessive force.

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

2Ease of operation

If reverse rotation is applied to release clamping, then the screwing means can be removed, but the tightening torque may be reduced

Engineering Contradiction:
Improverelease processVSAvoidtightening torque
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The patent employs periodic alternating torque application where the drive unit alternates between applying tightening torque in the first rotational direction and reverse rotation torque in the second rotational direction. This periodic action allows the system to achieve both tight screwing and easy release by cycling through tightening phases and release phases, maintaining tightening torque integrity while enabling straightforward removal when needed.

Inventive Principle:
Principle #19Periodic action

3Ease of operation

If additional tools are used to release clamping, then the screwing means can be removed, but the device complexity increases

Engineering Contradiction:
Improverelease processVSAvoidtool requirements
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The handheld power tool is equipped with a built-in drive unit capable of applying reverse rotation torque to the screwing means. This self-service capability allows the tool to release its own clamping condition without requiring external tools or assistance. The drive unit automatically reverses rotation to loosen and release the screwing means, making the tool self-sufficient and eliminating the need for additional release tools.

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

This method allows for reliable and efficient screwing and unscrewing without reducing the tightening torque, preventing tool jamming and damage, and simplifying the release process, ensuring operator safety and efficiency.

Implementation Method 1

Clamping can be generated by elastic deformation and subsequent bracing of the handheld power tool, in particular the torque transmission area of ​​the handheld power tool, relative to the screwing means

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP3856462B1Method for controlling or regulating a hand-held power tool
Publication Date: 2024.04.17 ROBERT BOSCH GMBH
  • EP3856462B1 patent drawingFigure 1
  • EP3856462B1 patent drawingFigure 2
  • EP3856462B1 patent drawingFigure 3

AI summary

The invention relates to a method for controlling or regulating a hand-held power tool, in particular a screwdriver, preferably a rotary percussion drill, comprising at least the following steps: applying screw means having a first torque, in particular a torque pulse, in a first direction of rotation, and subjecting the screw means having a second torque, in particular a torque pulse, in a second direction of rotation opposite to the first direction of rotation.