Impact Tool Counterweight Nesting for Compact Design

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Solution Overview

Problem

Existing impact tools face challenges in size reduction due to the need for multiple clearances to avoid interference when a counter weight is disposed outside the inner housing, which limits the tool body's compactness.

Innovation Solution

The counter weight is positioned inside the inner housing, reducing the need for clearances between the counter weight and the outer housing, and is designed to rotate on a pivot shaft, allowing it to counteract vibration effectively while being formed in a closed ring-like shape for enhanced durability and ease of assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the counter weight is disposed outside the inner housing, then the counter weight can be easily assembled and disassembled, but multiple clearances are required between the counter weight and the housing, preventing size reduction of the tool body

Engineering Contradiction:
Improveease of assemblyVSAvoidtool body size
Core Design Contradiction:
Ease of manufactureVSVolume of moving object

Solution Approach 1:

The counter weight is disposed inside the inner housing, nesting the counter weight within the housing structure. This eliminates the need for external clearances between the counter weight and outer housing, allowing the tool body to be reduced in size while maintaining the vibration reduction function.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The counter weight is positioned in the radial direction within the inner housing rather than externally, changing the spatial arrangement from an external radial position to an internal radial position. This dimensional repositioning allows the tool body to be more compact.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Volume of moving object

If the counter weight is disposed inside the inner housing, then the tool body size can be reduced by minimizing clearances, but the counter weight may interfere with other components during operation

Engineering Contradiction:
Improvetool body sizeVSAvoidinterference with components
Core Design Contradiction:
Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The inner housing is provided with a specific opening structure at a predetermined location that allows the counter weight to swing through a controlled range of motion. This localized structural feature ensures the counter weight does not interfere with other components while maintaining its vibration reduction function.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The counter weight is designed to swing dynamically within the inner housing rather than being fixed, allowing it to move through a controlled arc that avoids interference with stationary components while maintaining contact with the swinging member for effective vibration reduction.

Inventive Principle:
Principle #15Dynamics

3Volume of moving object

If the counter weight is disposed inside the inner housing, then the number of clearances is reduced for compactness, but the counter weight must be precisely positioned to avoid interference

Engineering Contradiction:
Improvetool body sizeVSAvoidpositioning precision
Core Design Contradiction:
Volume of moving objectVSManufacturing precision

Solution Approach 1:

The counter weight is pre-positioned and fixed to the swinging member at a specific location before assembly. This preliminary positioning ensures that when the counter weight swings inside the inner housing, it follows a predetermined path that avoids interference with other components, reducing the need for high manufacturing precision during final assembly.

Inventive Principle:
Principle #10Preliminary action

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 allows for a more compact tool body design by minimizing the number of required clearances and enhances vibration reduction and durability, while also simplifying mounting and repair processes.

Implementation Method 1

a counter weight that is disposed within the internal space of the inner housing and reduces vibration caused when the tool bit is driven

Methodology Applied
Scientific EffectVibration reduction: Damping

Data Source

PatentEP2540448B1Impact tool
Publication Date: 2017.08.02 MAKITA CORP
  • EP2540448B1 patent drawingFigure 1
  • EP2540448B1 patent drawingFigure 2
  • EP2540448B1 patent drawingFigure 3

AI summary

An impact tool in which a tool body can be effectively reduced in size is provided. The impact tool has a motor 111, a swinging member 129 that is driven by the motor 111 and swings in the axial direction of the tool bit, a striking mechanism 115 that is driven by components of linear motion in the axial direction of the tool bit in the swinging motion of the swinging member 129, a connecting part 124 that connects the swinging member 129 and the striking mechanism 115, a housing member 151 that houses at least the connecting part 124 in an internal space 156, and a counter weight 155 that is disposed within the internal space 156 of the housing member 151 and reduces vibration caused when the tool bit is driven.