Battery Connection Asymmetry for Electric Tool Weight Balance

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Solution Overview

Problem

In electric tools like mowing machines, the interchangeability of batteries with the same rated voltage can disrupt the weight balance, leading to operability issues, necessitating a solution to prevent the use of non-dedicated batteries even if they are compatible with the tool's voltage.

Innovation Solution

The design incorporates specific dimensional mismatches in the battery and tool connections, such as varying linear projection dimensions and slit configurations, to prevent the attachment of batteries other than the dedicated type, ensuring only the dedicated battery can be used, thus maintaining weight balance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If interchangeability is given between battery adapter and battery having the same rated voltage, then versatility is improved, but weight balance deteriorates

Engineering Contradiction:
Improvebattery interchangeabilityVSAvoidweight balance
Core Design Contradiction:
Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent applies asymmetry by creating dimensional mismatches in the connection interfaces. The battery adapter has different linear projection dimensions and slit configurations compared to the dedicated battery, making the connection interface asymmetric. This prevents interchangeable connection while maintaining voltage compatibility, thereby preserving weight balance without sacrificing versatility for tools that accept the standardized battery.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The patent applies local quality by making specific dimensional modifications to particular features of the connection interface. The linear projection dimensions and slit configurations are locally adjusted in the battery adapter compared to the dedicated battery. This localized dimensional differentiation prevents unauthorized substitution while allowing the rest of the battery design to maintain standard specifications for voltage compatibility.

Inventive Principle:
Principle #3Local quality

2Reliability

If connection prohibition portions are added to prevent non-dedicated battery attachment, then reliability is improved, but device complexity increases

Engineering Contradiction:
Improvebattery compatibility controlVSAvoidconnection structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical locking or electronic verification systems with a simpler dimensional compatibility system. Instead of using mechanical interlocks or electronic authentication, the invention uses dimensional mismatches in the connection interface itself to prevent incompatible battery attachment. This reduces device complexity while maintaining reliability in controlling battery compatibility.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP2397277B1Motor-driven tool
Publication Date: 2024.11.06 MAKITA CORP
  • EP2397277B1 patent drawingFigure 1
  • EP2397277B1 patent drawingFigure 2
  • EP2397277B1 patent drawingFigure 3

AI summary

For a specific electric tool, the present invention prohibits attachment of other battery than a dedicated battery even that compatible with the rated voltage of the electric tool. An electric tool main body of an electric tool according the present invention is provided with a battery retaining portion (28), and a battery (30) is provided with a fitting portion (36t) capable of fitting with the battery retaining portion (28); the battery (30) is connected to the electric tool main body through a sliding motion in a predetermined direction with respect to the electric tool main body in the state that the battery retaining portion (28) is fitted with the fitting portion (36t); the electric tool main body is provided with a connection prohibition portion (45) prohibiting connection of other battery than the dedicated battery even if the battery is compatible with the rated voltage of the electric tool main body.