Impact Tool Vibration Suppression via Variable Motor Speed

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing impact tools generate unnecessary vibration during the non-pressed state, which can be detrimental to user safety and operational efficiency.

Innovation Solution

An impact tool equipped with a brushless motor, a driving mechanism, a vibration suppressing mechanism featuring a movable weight or dynamic vibration reducer, and a controller that adjusts the motor's rotation speed based on the tool's state (pressed or non-pressed) to minimize vibration. The controller switches between a first rotation speed during the pressed state and a lower second rotation speed during the non-pressed state to suppress unwanted movement and vibration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the driving mechanism operates the swinging member in the non-pressed state to enable quick transition to hammering operation, then the responsiveness and safety are improved, but unnecessary vibration is generated due to reciprocating movement of the counter weight

Engineering Contradiction:
ImproveresponsivenessVSAvoidvibration
Core Design Contradiction:
Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The patent applies dynamics by making the motor rotation speed variable based on operational state. The controller dynamically adjusts the motor speed between a first rotation speed (during hammering operation) and a second rotation speed (during non-pressed state), optimizing both responsiveness and vibration reduction through speed variation rather than fixed operation

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the operational parameter of motor rotation speed according to the state of the tool. By switching between different rotation speeds (first rotation speed for hammering, second rotation speed for non-pressed state), the system achieves both quick transition capability and vibration suppression in the non-pressed state

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

Effectively reduces vibration in the non-pressed state, enhancing user safety and operational efficiency by minimizing unnecessary movement and vibration, thereby improving the overall performance of the impact tool.

Implementation Method 1

a brushless motor (110), a driving mechanism (120, 160) that drives the tool accessory by an output of the brushless motor

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a vibration suppressing mechanism (160, 490) having a movable weight (490), and a controller (112) that controls driving of the brushless motor

Methodology Applied
Scientific EffectDynamic vibration reduction: Tuned Mass Damper

Data Source

PatentEP3184259B1Impact tool
Publication Date: 2022.02.16 MAKITA CORP
  • EP3184259B1 patent drawingFigure 1
  • EP3184259B1 patent drawingFigure 2
  • EP3184259B1 patent drawingFigure 3

AI summary

It is an object of the invention to provide a further rational technique for reducing vibration in a non-pressed state for an impact tool. A representative electric hammer (100) has a driving mechanism (160) for driving a tool bit (119), a vibration suppressing mechanism (190) having a movable weight, and a controller (112) for controlling driving of an electric motor (110). In a pressed state that the tool bit (119) is pressed against a workpiece by a user, the controller (112) drives the electric motor (110) at a first rotation speed, and in a non-pressed state that the tool bit (119) is not pressed against the workpiece by the user, the controller (112) drives the electric motor (110) at a second rotation speed lower than the first rotation speed.