Reciprocating Power Tool Anti-Jamming Torsion Spring Mechanism

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Solution Overview

Problem

Motorized hedge trimmers often jam when encountering obstacles, leading to reduced efficiency and increased effort in gardening tasks, as existing solutions do not effectively address the issue of blade jamming during operation.

Innovation Solution

A reciprocating power tool with a torsion spring mechanism that is charged during motor operation and reverses the cutting mechanism when the motor is terminated, using a driving assembly with a gear member, cover member, and eccentric cams to un-jam the blades by reversing their direction upon detection of a jam.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If motorized trimmers are used to trim faster with less effort, then productivity is improved, but the blades may jam when encountering obstacles, reducing efficiency

Engineering Contradiction:
Improvetrimming speedVSAvoidblade jamming
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The resilient arrangement is pre-loaded during normal operation to store energy, preparing the system in advance to reverse the blades when jamming occurs. This preliminary energy storage enables automatic unjamming without user intervention.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The jamming force that stops blade movement is converted into a useful function: the resilient arrangement uses the stored energy to reverse the blades, transforming the harmful jamming condition into a beneficial automatic unjamming mechanism.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

2Ease of operation

If significant effort is applied to un-jam the hedge trimmer, then the blades can be freed, but the efficiency of gardening works suffers due to loss of time

Engineering Contradiction:
Improveunjamming effortVSAvoidtime lost during unjamming
Core Design Contradiction:
Ease of operationVSLoss of time

Solution Approach 1:

The system performs unjamming automatically through the resilient arrangement reversing the blades without user intervention. The mechanism serves itself by using stored energy to free the blades, eliminating the need for manual unjamming efforts.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

Energy is stored in the resilient arrangement during normal operation, preparing the system in advance to automatically reverse the blades when jamming occurs, eliminating time loss during unjamming.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If a resilient arrangement is used to reverse the cutting mechanism, then automatic unjamming is achieved, but the device complexity increases

Engineering Contradiction:
Improveanti-jamming capabilityVSAvoiddriving assembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The resilient arrangement serves multiple functions: it stores energy during normal operation, reverses the blades when jamming occurs, and provides automatic unjamming. This multi-functionality reduces the need for separate dedicated unjamming mechanisms.

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

Solution Approach 2:

The resilient arrangement is integrated into the existing driving assembly, combining the energy storage and blade reversal functions with the motor-driven cutting mechanism, rather than adding a separate unjamming system.

Inventive Principle:
Principle #5Merging (Combining)

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 tool effectively un-jams the blades by reversing their direction when a jam is detected, allowing for efficient resumption of operation after the user re-activates the motor, providing a robust anti-jamming mechanism and additional safety protection.

Implementation Method 1

the resilient arrangement includes a torsion spring arranged to be charged when the cutting mechanism is driven by the motor and discharged when the drive from the motor is terminated to reverse the cutting mechanism

Methodology Applied
Scientific EffectElastic energy storage: Spring

Implementation Method 2

the torsion spring is charged by friction between the torsion spring and the driving assembly

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP2878191B1Reciprocating power tool
Publication Date: 2018.03.28 TECHTRONIC OUTDOOR PRODS TECH
  • EP2878191B1 patent drawingFigure 1
  • EP2878191B1 patent drawingFigure 2~3
  • EP2878191B1 patent drawingFigure 4

AI summary

The present invention provides a reciprocating power tool (10) comprising a reciprocating cutting mechanism (102, 104) arranged to be driven by a motor via a driving assembly (100), wherein the driving assembly includes a resilient arrangement (126) arranged to be charged when the cutting mechanism is driven by the motor and, whereupon the drive from the motor is terminated, the resilient arrangement is arranged to reverse the cutting mechanism from the direction of the drive from the motor. By including a simple yet robust anti-jamming mechanism for un-jamming the blades, the present invention provides a reciprocating power tool with improved effectiveness and efficiency for operational use.