Impact Tool Hammer Inertia Ratio for Efficient Energy Transfer

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Solution Overview

Problem

Existing impact tools suffer from inefficiencies in energy transfer due to clearances and imbalances between the hammer and anvil, leading to significant energy loss without effectively tightening fastening members.

Innovation Solution

The impact tool design increases the moment of inertia of the hammer relative to the anvil by incorporating a skirt part or a combination of main and sub-hammers, ensuring the hammer's moment of inertia is 10 or more times that of the anvil, thereby optimizing energy transfer and reducing energy loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the hammer and anvil have comparable moments of inertia, then the device structure remains compact and simple, but energy transfer efficiency deteriorates due to clearances and imbalances

Engineering Contradiction:
Improveenergy transfer efficiencyVSAvoidhammer structure complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by modifying the moment of inertia of the hammer relative to the anvil. Specifically, the hammer is designed with a moment of inertia that is 10 or more times greater than that of the anvil, which fundamentally changes the dynamic characteristics of the impact mechanism. This parameter adjustment optimizes energy transfer efficiency by reducing the impact of clearances and imbalances during operation.

Inventive Principle:
Principle #35Parameter changes

2Loss of energy

If the hammer's moment of inertia is increased significantly, then energy efficiency improves, but the tool size and weight increase

Engineering Contradiction:
Improveenergy efficiencyVSAvoidhammer weight
Core Design Contradiction:
Loss of energyVSWeight of moving object

Solution Approach 1:

The patent applies local quality by concentrating mass distribution in specific regions of the hammer to achieve the required moment of inertia ratio. Instead of uniformly increasing the hammer's mass throughout, the design focuses mass strategically to optimize the moment of inertia while controlling overall weight and tool dimensions.

Inventive Principle:
Principle #3Local quality

3Loss of energy

If the hammer's moment of inertia is increased significantly, then energy efficiency improves, but the tool size increases

Engineering Contradiction:
Improveenergy efficiencyVSAvoidhammer volume
Core Design Contradiction:
Loss of energyVSVolume of moving object

Solution Approach 1:

The patent applies local quality by concentrating mass distribution in specific regions of the hammer to achieve the required moment of inertia ratio. Instead of uniformly increasing the hammer's mass throughout, the design focuses mass strategically to optimize the moment of inertia while controlling overall weight and tool dimensions.

Inventive Principle:
Principle #3Local quality

4Force

If conventional hammer and anvil design is used, then device complexity remains low, but torque output and tightening effectiveness deteriorate

Engineering Contradiction:
Improvetorque outputVSAvoidhammer-anvil mechanism complexity
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by modifying the moment of inertia of the hammer relative to the anvil. Specifically, the hammer is designed with a moment of inertia that is 10 or more times greater than that of the anvil, which fundamentally changes the dynamic characteristics of the impact mechanism. This parameter adjustment optimizes energy transfer efficiency by reducing the impact of clearances and imbalances during operation.

Inventive Principle:
Principle #35Parameter changes

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 design improves energy efficiency, allowing for more effective tightening of fastening members with increased torque and reduced noise and heat generation, while maintaining a compact tool size.

Implementation Method 1

moment of inertia of the hammer around the rotation axis is 10 or more times moment of inertia of the anvil around the rotation axis

Methodology Applied
Scientific EffectMoment of Inertia: Moment of Inertia

Data Source

PatentEP4112228B1Impact tool
Publication Date: 2025.08.27 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD
  • EP4112228B1 patent drawingFigure 1
  • EP4112228B1 patent drawingFigure 2
  • EP4112228B1 patent drawingFigure 3

AI summary

An object of the present disclosure is to improve energy efficiency. An impact tool (1) includes a motor (3), a hammer (42), and an anvil (45). The hammer (42) is configured to be rotated around a rotation axis (Axl) by motive power provided from the motor (3). The anvil (45) is configured to be rotated around the rotation axis (Axl) by receiving striking force from the hammer (42) in a circumferential direction of the rotation axis (Axl). In the impact tool (1), moment of inertia of the hammer (42) around the rotation axis (Axl) is 10 or more times moment of inertia of the anvil (45) around the rotation axis (Axl).