Handheld Cutting Tool Torque Control for Automatic Jam Release

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Solution Overview

Problem

Hand-held processing devices, such as power tools and gardening equipment, often experience tool jamming due to blockages, requiring users to manually intervene and adjust controls, which can be inconvenient and inefficient.

Innovation Solution

An automated method and device that independently monitor for blockages, reduce torque when a jamming criterion is detected, and then increase torque to clear the blockage without user intervention, allowing for continuous operation and user notification of jamming through haptic or acoustic signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If manual intervention is required to release tool blockages, then user control over the device is maintained, but operational continuity is interrupted and user effort increases

Engineering Contradiction:
Improveoperational continuityVSAvoiduser effort
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The device automatically detects blockages through monitoring means and releases them through controlled torque reduction and reversal, enabling the system to service itself without user intervention. The control means autonomously manages the entire blockage release process including detecting the blocked state, reducing torque to free the cutting tool, and restoring normal operation.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system performs preliminary detection of blockage conditions through monitoring means before complete jamming occurs. By identifying blocked states early and automatically initiating torque reduction, the system prevents full blockage development and maintains continuous operation without requiring user response.

Inventive Principle:
Principle #10Preliminary action

2Productivity

If automated blockage detection and release is implemented, then operational continuity is improved, but device complexity increases

Engineering Contradiction:
Improveoperational continuityVSAvoidcontrol system complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The control means performs multiple functions including normal torque control, blockage detection through monitoring means integration, automated torque reduction, and torque reversal for blockage release. This multi-functionality consolidates what could be separate complex systems into a single integrated control unit, managing to reduce overall system complexity while achieving automated blockage handling.

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

Solution Approach 2:

The monitoring means continuously provides feedback on the operational state of the cutting tool to the control means. This feedback loop enables automatic detection of blocked states and triggers appropriate control actions. The system adjusts torque based on real-time feedback, creating a self-regulating mechanism that simplifies the control architecture through intelligent response to sensor data.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3854556B1Handheld processing device and method for operating same
Publication Date: 2024.03.06 ANDREAS STIHL AG & CO KG
  • EP3854556B1 patent drawingFigure 1~2
  • EP3854556B1 patent drawingFigure 3~4
  • EP3854556B1 patent drawingFigure 5

AI summary

The invention relates to a method for operating a hand-held processing device (1), wherein the processing device (1) comprises: - a rotating and/or circulating cutting tool (2), - an electric motor drive system (3), wherein the electric motor drive system (3) is configured to generate a torque (M) for driving the cutting tool (2), and - a user-operated control element (4), wherein the method comprises the steps: a) automatically monitoring whether a blocking criterion (BC) is met, wherein the blocking criterion (BC) is characteristic of a blockage of the cutting tool (2), and b) if the blocking criterion (BC) is met and the control element (4) is operated, automatically reducing the torque (M) generated by the electric motor drive system (3) and subsequently automatically increasing the torque (M) generated by the electric motor drive system (3).