Hand-held Power Tool Jamming Release via Reverse Rotation

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Solution Overview

Problem

Hand-held power tools, such as rotary impact wrenches, often experience jamming issues when tightening fasteners due to high moments and impulse-like loads, making it difficult to release jammed nuts or bits without applying considerable force, which can lead to injury and require additional tools.

Innovation Solution

A method for operating hand-held power tools that involves rotating the tool holder in a second direction opposite to the initial rotation at a predefined speed and duration to loosen jammed fasteners without fully unscrewing them, using sensors and automatic detection to monitor and address jamming, and adjustable parameters for efficient operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If high torque and impact operation are used to tighten fasteners, then tightening capability is improved, but jamming of the drive or interface occurs frequently

Engineering Contradiction:
Improvetightening capabilityVSAvoidjamming frequency
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The patent applies reverse rotation to release jamming. After detecting a jamming event during forward rotation (tightening operation), the system automatically rotates the tool holder in the opposite direction to loosen and release the jammed components, then restores forward rotation to continue the tightening task.

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

Solution Approach 2:

The system uses sensors to detect jamming events during operation and provides feedback to the control unit. Based on this feedback, the control unit automatically adjusts the rotation direction and parameters to release jamming, enabling closed-loop control that prevents operation interruption.

Inventive Principle:
Principle #23Feedback

2Ease of operation

If considerable force is applied to release jammed fasteners, then jamming is released, but risk of injury and damage increases

Engineering Contradiction:
Improvejamming release capabilityVSAvoidinjury risk
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The system performs self-diagnosis and self-release of jamming events. When jamming is detected through sensor feedback, the control unit automatically initiates reverse rotation to release the jamming, eliminating the need for manual intervention and reducing injury risk from forced release attempts.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The control unit acts as an intermediary between the motor and tool holder, mediating the release process by automatically controlling reverse rotation when jamming occurs, thereby preventing direct manual force application that could cause injury.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If additional tools are used to release jammed fasteners, then jamming is released, but device complexity and operation time increase

Engineering Contradiction:
Improvejamming release reliabilityVSAvoidtool requirement
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The power tool is designed with multi-functionality, combining both tightening (forward rotation) and jamming release (reverse rotation) capabilities in a single device. The motor can rotate in both directions, and the control unit manages both functions, eliminating the need for separate release tools.

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

Solution Approach 2:

The patent merges the tightening and jamming release functions into a single integrated system. The control unit combines detection, decision-making, and execution of reverse rotation within the same device, consolidating multiple operations that would otherwise require separate tools into one unified tool.

Inventive Principle:
Principle #5Merging (Combining)

4Reliability

If reverse rotation is used to release jamming, then jamming is released, but fastener may be loosened

Engineering Contradiction:
Improvejamming release effectivenessVSAvoidfastener retention
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The system applies partial reverse rotation action - rotating in reverse just enough to release jamming without fully loosening the fastener. The control unit limits the duration and extent of reverse rotation to minimize fastener loosening while achieving jamming release, then immediately restores forward rotation.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP4406700A1Method for operating a hand-held power tool
Publication Date: 2024.07.31 ROBERT BOSCH GMBH
  • EP4406700A1 patent drawingFigure 1
  • EP4406700A1 patent drawingFigure 2~3
  • EP4406700A1 patent drawingFigure 4

AI summary

Method for operating a hand-held power tool, in particular an impact wrench, the hand-held power tool comprising a tool holder for receiving a tool such as a tool bit or a socket, wherein the tool is configured to drive the fastening element rotationally via a corresponding drive of a fastening element; the method comprising the steps: S1 Screwing the fastening element into a substrate, rotating the tool holder and thus the fastening element in a first direction of rotation; S2 Rotating the tool holder in a second direction of rotation opposite to the first direction of rotation, at a predefined speed and for a predefined time period.