Impact Tool Biasing Member Dust Protection

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Solution Overview

Problem

The existing mode switching mechanisms in impact tools are prone to durability issues due to dust exposure, as the biasing members are typically disposed outside the housing and not adequately protected.

Innovation Solution

The impact tool design incorporates a biasing member, such as a leaf spring, disposed within the housing space to protect it from dust, along with a sealing member like an O-ring to prevent lubricant leakage and dust entry, enhancing the biasing member's durability and wear resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the biasing member is disposed outside the housing, then the structure is simpler and easier to access, but the biasing member is exposed to dust which impairs its durability

Engineering Contradiction:
Improvestructural simplicityVSAvoidbiasing member durability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The biasing member is nested inside the housing space, placing it within the protected internal environment of the housing. This nesting arrangement shields the biasing member from external dust while maintaining structural integrity, resolving the contradiction between accessibility and durability.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

A sealing member (flexible shell) is introduced to close the opening of the housing space, creating a dust-proof barrier. This flexible sealing element protects the biasing member from dust exposure while allowing the housing to maintain its structural form, thereby improving durability without significantly increasing complexity.

Inventive Principle:
Principle #30Flexible shells and thin films

2Reliability

If the biasing member is disposed inside the housing space, then the biasing member is protected from dust, but the housing structure becomes more complex

Engineering Contradiction:
Improvebiasing member durabilityVSAvoidhousing structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The biasing member is nested inside the housing space, utilizing the existing housing structure to provide protection. This approach minimizes additional structural complexity while achieving dust protection, as the housing itself serves as the protective enclosure.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

A sealing member is added to close the housing opening, providing dust protection with minimal structural modification. The flexible sealing element requires only a small addition to the housing structure, thereby limiting the increase in overall device complexity while effectively protecting the biasing member.

Inventive Principle:
Principle #30Flexible shells and thin films

3Reliability

If a sealing member is added to prevent dust entry, then the biasing member is protected, but the device complexity increases

Engineering Contradiction:
Improvedust protection effectivenessVSAvoidsealing structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

A sealing member (flexible shell such as O-ring) is used to close the housing opening. This flexible sealing element provides effective dust protection with a simple, compact design that does not significantly increase device complexity. The sealing member is easily integrated into the existing housing structure.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The sealing member is designed as a simple, inexpensive component that can be easily replaced if needed. This approach minimizes the impact on overall device complexity and cost, while providing reliable dust protection for the biasing member during the tool's service life.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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

This configuration effectively shields the biasing member from dust, improving its durability and ensuring reliable operation by maintaining the lubrication within the housing space, thus enhancing the overall performance and longevity of the impact tool.

Implementation Method 1

a biasing member which is disposed between the operating member and the housing part and biases the operating member so as to hold it in a selected position

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

a sealing member is provided between the housing part and the operating member... the sealing member prevents the lubricant from leaking to the outside of the housing space

Methodology Applied
Scientific EffectSealing:

Implementation Method 3

a lubricant for lubricating the driving mechanism is provided in the housing space... a sliding part of the driving mechanism can be reliably lubricated by the lubricant

Methodology Applied
Scientific EffectLubrication: Lubrication

Data Source

PatentEP2732925B1Impact tool
Publication Date: 2018.01.03 MAKITA CORP
  • EP2732925B1 patent drawingFigure 1
  • EP2732925B1 patent drawingFigure 2
  • EP2732925B1 patent drawingFigure 3

AI summary

Impact tool with a driving mechanism (120) for driving a tool bit (119), housing parts (105, 106) that form a housing space (105a) in which at least part of the driving mechanism (120) is disposed, and a switching member (160) for switching a drive mode of the impact tool. The switching member (160) has an operating member (161) that is operated by a user for mode switching, and a biasing member (175) that is disposed between the operating member (161) and the housing part (106) and biases the operating member (161) so as to hold the operating member (161) in a selected position. The biasing member (175) is disposed in the housing space (105a).