String Trimmer Spool Winding Mechanism

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Solution Overview

Problem

Existing string trimmers require cumbersome and time-consuming processes for replacing cutting line, often necessitating manual spool rotation and disassembly, which is inefficient for both residential and professional users.

Innovation Solution

A string trimmer with a winding button that automatically rotates the spool using a motor control module, allowing users to wind new cutting line without manual knob turning, ensuring safe and controlled operation by keeping the spool housing stationary.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If manual spool rotation is used to wind cutting line, then the winding process can be completed, but the operation becomes cumbersome and time-consuming

Engineering Contradiction:

Improveease of cutting line replacementVSAvoidtime for winding cutting line

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The patent replaces the manual mechanical rotation system with an automated motor-driven system. The motor control module automatically rotates the spool to wind cutting line, eliminating the need for users to manually turn the spool, thereby reducing both operational effort and time required for line replacement

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The winding mechanism is designed to perform the winding operation automatically once activated. The system serves itself by using the motor to rotate the spool and wind the line without requiring continuous manual intervention, making the process more efficient and less labor-intensive

Inventive Principle:

Principle #25Self-service

2Ease of operation

If the spool housing rotates during winding, then the winding process may be simpler, but safety risks increase due to uncontrolled spool rotation

Engineering Contradiction:

Improveease of winding operationVSAvoidsafety hazards from uncontrolled rotation

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent separates the spool rotation function from the spool housing. Only the spool itself rotates while the housing remains stationary, isolating the rotational movement to a controlled component. This segmentation allows the winding mechanism to function effectively while preventing uncontrolled housing rotation that could create safety hazards

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The motor control module provides controlled rotation with inherent feedback mechanisms that regulate the spool's movement. This ensures the spool rotates at a controlled speed and stops when winding is complete, preventing unsafe uncontrolled rotation while maintaining ease of operation

Inventive Principle:

Principle #23Feedback

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

Facilitates quick and simple replacement of cutting line, reducing user effort and time, while ensuring safety by automating the winding process and controlling motor speed and direction.

Implementation Method 1

A string trimmer with a winding button that automatically rotates the spool using a motor control module

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3308622B1Powered spool line winding mechanism for string trimmer

Publication Date: 2020.06.10 BLACK & DECKER CORP

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AI summary

A string trimmer having a cutting head with a spool, where replacement cutting line can be wound onto the spool. The trimmer includes a powered winding button that rotates a motor in a reverse direction from its operation direction, and at a slower speed to wind the replacement cutting line.