Planetary Gear Counterweighting in Reciprocating Tools for Low Vibration

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Solution Overview

Problem

Existing power-driven reciprocating tools experience significant vibration due to acceleration/deceleration at extreme ends of travel, especially at increased operational speed and stroke length, affecting user control, precision, and causing fatigue.

Innovation Solution

A power-driven reciprocating tool incorporating a planetary gear assembly and counterweighting mechanism to convert rotational force into linear motion, with a counterbalance mechanism that counteracts imbalances, reducing vibration and enhancing user control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If operational speed and stroke length of the output spindle are increased, then productivity is improved, but vibration increases causing user fatigue and reduced control

Engineering Contradiction:
Improveoperational speed and stroke lengthVSAvoidvibration
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

A counterbalance mechanism is integrated into the reciprocating mechanism, comprising a counterbalance arm coupled to the reciprocating component and a counterbalance weight positioned to offset the reciprocating component's mass. This counterweight system generates opposing inertial forces that cancel out vibrations produced during high-speed operation, enabling increased productivity without exacerbating user fatigue

Inventive Principle:
Principle #8Anti-weight (Counterweight)

2Ease of operation

If a compact tool profile is provided, then ease of operation in confined spaces is improved, but device complexity increases due to additional balancing mechanisms

Engineering Contradiction:
Improveaccess to smaller, tighter spacesVSAvoidreciprocating mechanism with counterbalancing
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The counterbalance mechanism is merged with the existing reciprocating mechanism structure. The counterbalance arm is coupled to the reciprocating component through shared structural elements, and the counterbalance weight is integrated into the same housing space. This merging approach provides vibration reduction functionality without requiring separate balancing assemblies, thereby limiting the increase in device complexity

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The counterbalance mechanism components are nested within the existing tool housing and structural framework. The counterbalance arm utilizes the same mounting points and structural support as the reciprocating mechanism, while the counterbalance weight is positioned within the available internal volume of the housing. This nesting arrangement achieves a compact overall profile that accommodates both the reciprocating and counterbalancing functions

Inventive Principle:
Principle #7Nested doll (Nesting)

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

The solution provides a compact tool profile for improved user control, reduced vibration, and decreased operator fatigue, enabling precise operation in confined spaces.

Implementation Method 1

A planetary gear assembly is aligned with the motor, and converts a rotational force generated by the motor to a linear force

Methodology Applied
Scientific EffectPlanetary gear mechanism: Epicyclic Gearing

Implementation Method 2

A counterbalance mechanism is coupled to the reciprocating mechanism, and counterbalances imbalances generated by the motor and the reciprocating mechanism

Methodology Applied
Scientific EffectCounterbalancing: Balance

Data Source

PatentEP3757427B1Reciprocating tool having planetary gear assembly and counterweighting assembly
Publication Date: 2025.11.19 BLACK & DECKER CORP
  • EP3757427B1 patent drawingFigure 1
  • EP3757427B1 patent drawingFigure 2A
  • EP3757427B1 patent drawingFigure 2B

AI summary

A power-driven reciprocating tool may include a transmission mechanism that converts rotational force from a motor to linear force to be output by a reciprocating mechanism coupled thereto, and a counterbalancing mechanism coupled to the transmission mechanism to counter-balance forces generated by the reciprocating mechanism. The transmission mechanism may include a planetary gear assembly including a sun gear in meshed engagement with at least one planet gear. In response to a force converted by and transmitted from the transmission mechanism, the reciprocating mechanism may move in a first linear direction, and the counterbalancing mechanism may move in a second linear direction, opposite the first linear direction. The opposite linear movement of the reciprocating mechanism and the counterbalancing mechanism may counteract forces generated by the reciprocating motion of the reciprocating mechanism, thus reducing vibration output by the tool.