Self-Locking Blade Cap for Tool-Free Robotic Mower Replacement

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Solution Overview

Problem

Existing garden tools, such as robotic lawn mowers, face challenges in securely attaching and easily removing blade modules without the need for tools, which can lead to unintentional loosening during operation.

Innovation Solution

A self-locking locking cap with a ratchet mechanism is used to securely attach the blade module to the drive shaft, preventing loosening during operation and allowing for tool-free removal by rotating the cap in a specific direction, which simultaneously releases the blade module.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a removable blade module is used in a robotic lawn mower, then ease of removal and replacement is improved, but reliability of attachment during operation deteriorates due to potential unintentional loosening

Engineering Contradiction:
Improveease of removalVSAvoidattachment security
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The locking cap incorporates a self-locking ratchet mechanism that automatically prevents loosening during operation without requiring additional locking actions or tools from the user. The system serves itself by maintaining secure attachment through the pawl-ratchet engagement during normal operation

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The locking mechanism transitions between two dynamic states: a locked state where the pawl engages the ratchet teeth to prevent loosening, and an unlocked state where the pawl is disengaged to allow removal. This dynamic behavior enables the same mechanism to provide both secure attachment during operation and easy removal when needed

Inventive Principle:
Principle #15Dynamics

2Reliability

If a self-locking mechanism is added to prevent loosening, then reliability of attachment is improved, but device complexity increases due to additional components

Engineering Contradiction:
Improveattachment securityVSAvoidmechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The locking cap merges multiple functions into a single component: it provides the locking action through the ratchet mechanism, the self-locking function through the pawl engagement, and the release function through the same structural elements. This consolidation reduces the number of separate parts compared to using distinct locking and releasing mechanisms

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The locking cap serves multiple purposes: it secures the blade module during operation through the ratchet mechanism, prevents unintentional loosening through the self-locking pawl engagement, and enables tool-free removal through the same structural design. This multi-functionality reduces the need for additional specialized components

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

3Ease of operation

If a ratchet mechanism with pawl and slider is used, then ease of operation for removal is improved, but device complexity increases due to additional moving parts

Engineering Contradiction:
Improveease of removalVSAvoidmechanism complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The ratchet mechanism is segmented into distinct functional components: the ratchet wheel with engagement teeth provides the locking structure, the pawl provides the self-locking action, and the slider provides the release function. This segmentation allows each component to be optimized for its specific function while working together as an integrated system

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The slider acts as an intermediary element that mediates between the user's removal action and the pawl's engagement state. When the user rotates the locking cap, the slider translates this motion into pawl disengagement, providing a mechanical advantage and making the removal process easier while isolating the complexity of the ratchet mechanism from direct user interaction

Inventive Principle:
Principle #24Intermediary (Mediator)

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 solution ensures secure attachment and easy, tool-free removal of blade modules, enhancing user convenience and preventing accidental detachment during operation.

Implementation Method 1

The locking cap may be self-locking by way of a ratchet mechanism; the ratchet mechanism may include a ratchet wheel, a pawl pivotable between a first pawl position and a second pawl position, and a slider slideable between a first slider position and a second slider position

Methodology Applied
Scientific EffectRatchet mechanism: Ratchet

Implementation Method 2

The ratchet mechanism may include a biasing member, such as a spring

Methodology Applied
Scientific EffectElastic potential energy: Spring

Implementation Method 3

The locking cap may be configured to thread onto the drive shaft by actuation in a first direction to secure the driven implement to the drive shaft

Methodology Applied
Scientific EffectScrew mechanism: Screw

Data Source

PatentEP4238404A1Robotic garden tool with quick change mechanism
Publication Date: 2023.09.06 TECHTRONIC CORDLESS GP
  • EP4238404A1 patent drawingFigure 1
  • EP4238404A1 patent drawingFigure 2
  • EP4238404A1 patent drawingFigure 3

AI summary

A garden tool includes a drive shaft, a driven implement, and a locking cap configured to removably secure the drive shaft and the driven implement relative to each other. The locking cap is self-locking to inhibit loosening. The locking cap may include a ratchet mechanism. The garden tool may include a vegetation cutter.