Power Impact Tool Counterweight Inversion for Axial Vibration Reduction

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Solution Overview

Problem

Existing power impact tools with swinging mechanisms experience vibration issues due to counterweights positioned below the swinging ring, leading to unnecessary vibration and energy loss during operation.

Innovation Solution

A counterweight is positioned higher than the lower end region of the swinging ring, connected to its lower end, and extends upward with a pivot point at the end, rotating in the axial direction to reduce vibration and energy loss, while being designed to avoid interference with the swinging ring and simplify the supporting structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the counter weight is disposed in a lower region apart from the swinging ring, then the counter weight can be connected to the lower end region of the swinging ring, but unnecessary vibration is caused by a couple around the horizontal axis and energy loss occurs due to sliding resistance

Engineering Contradiction:
Improveconnection structureVSAvoidvibration and energy loss
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent inverts the conventional arrangement by positioning the counterweight above the swinging ring instead of below it. The counterweight is disposed in a region higher than the lower end region of the swinging ring in the vertical direction, and a lower end of the counterweight is connected to the lower end region of the swinging ring. This inversion eliminates the harmful couple around the horizontal axis and reduces energy loss.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the spatial arrangement from a horizontal/vertical mixed configuration to a purely vertical configuration. The counterweight is positioned in the vertical direction above the swinging ring, aligned with the axis of the tool bit, which eliminates the horizontal offset that causes the harmful couple and reduces vibration.

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

2Ease of operation

If the counter weight is disposed away from the axis of the tool bit, then the counter weight can be connected to the swinging ring, but unnecessary vibration is caused by a couple around the horizontal axis

Engineering Contradiction:
Improvevibration reduction functionVSAvoidcouple-induced vibration
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent inverts the position of the counterweight from a location that creates a horizontal offset to a location that aligns vertically with the tool bit axis. By positioning the counterweight above the swinging ring and connecting it to the lower end region, the counterweight acts along the same vertical axis as the tool bit, eliminating the harmful couple.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent creates an asymmetric vertical arrangement where the counterweight is positioned at a specific height above the swinging ring, disconnected from the horizontal symmetry that would create couples. The vertical asymmetric positioning eliminates the horizontal couple while maintaining the vibration reduction function.

Inventive Principle:
Principle #4Asymmetry

3Object-affected harmful factors

If the counter weight linearly moves by the swinging movement of the swinging ring, then the counter weight can reduce vibration, but energy loss occurs due to resistance of the sliding area

Engineering Contradiction:
Improvevibration reductionVSAvoidsliding resistance loss
Core Design Contradiction:
Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The patent inverts the motion type of the counterweight from linear sliding motion to rotational motion. The counterweight rotates about a pivot point during the swinging movement of the swinging ring, which eliminates sliding resistance and the associated energy loss while maintaining the vibration reduction effect through the rotational movement.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent introduces rotational motion which inherently involves curved paths rather than linear sliding. The counterweight rotates about a pivot point, following a curved arc during operation, which eliminates the sliding contact and associated friction losses that would occur with linear movement.

Inventive Principle:
Principle #14Spheroidality (Curvature)

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 reduces axial and vertical vibrations, minimizes energy loss, and simplifies the structure, enhancing the vibration-reducing performance and manufacturing efficiency of power impact tools.

Implementation Method 1

a counter weight that reduces vibration caused in the axial direction of the tool bit during the operation is provided. The counter weight is disposed in a region higher than a lower end region of the swinging ring in the vertical direction that intersects with the axis of the rotating shaft. Further, a lower end of the counter weight is connected to the lower end region of the swinging ring. The counter weight extends upward from the connection between the counter weight and the swinging ring and has a pivot point in the extending end portion. When the swinging ring swings, the counter weight is driven by the swinging ring and caused to rotate in the axial direction of the tool bit, thereby reducing vibration caused in the axial direction of the tool bit.

Methodology Applied
Scientific EffectInertia: Inertia

Data Source

PatentEP2540449B1Power impact tool
Publication Date: 2017.02.22 MAKITA CORP
  • EP2540449B1 patent drawingFigure 1
  • EP2540449B1 patent drawingFigure 2
  • EP2540449B1 patent drawingFigure 3

AI summary

It is an object of the invention to provide a technique for further improving the vibration reducing a performance in a power impact tool (101) that linearly drives a tool bit (119) by using a swinging mechanism. A representative power impact tool (101) is provided with a motor (111), a rotating shaft (125), a swinging member (129), a tool driving mechanism (141,143,145) and a counter weight (153;163). The swinging member (129) is supported by the rotating shaft (125) to swing in the axial direction of the rotating shaft (125) by rotation of the rotating shaft (125). The counter weight (153;163) is disposed in a region higher than a lower end region of the swinging member (129) in the vertical direction to intersect with the axis of the rotating shaft (125), and a lower end of the counter weight (153;163) is connected to the lower end region of the swinging member (129). The counter weight (153;163) extends upward from the connection between the counter weight (153;163) and the swinging member (129) and has a pivot point in the extending end portion, and when the swinging member (129) swings, the counter weight (153;163) is driven by the swinging member (129) to rotate in the axial direction of the tool bit (119), thereby reducing vibration caused in the axial direction of the tool bit (119).