Reciprocating Tool Counterweight Layout for Low-Vibration Cutting

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Solution Overview

Problem

Existing reciprocating tools face challenges in efficiently translating rotary motion into reciprocating motion while minimizing vibrations and reducing tool size, particularly in tight spaces or awkward angles.

Innovation Solution

A power tool design featuring a counterweight and spindle mechanism that translate rotary motion into reciprocating motion, with a counterweight and spindle reciprocating parallel and opposite to each other, and a gear case with elastic members to absorb axial vibrations, reducing tool size and enhancing stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a traditional reciprocating mechanism is used to translate rotary motion into reciprocating motion, then the cutting function is achieved, but the tool size becomes large and vibrations increase

Engineering Contradiction:

Improvetool sizeVSAvoidcutting function

Core Design Contradiction:

Volume of moving objectVSEase of operation

Solution Approach 1:

The patent places the counterweight mechanism inside the gear case housing, nesting multiple functional components within a compact structure. The counterweight assembly is positioned within the existing gear case volume, allowing the reciprocating mechanism to be integrated without increasing overall tool size, thus resolving the contradiction between achieving cutting function and maintaining compact dimensions

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent introduces a counterweight mechanism that offsets vibrations generated during reciprocating motion. The counterweight is configured to move in opposition to the spindle, balancing the dynamic forces and reducing vibrations, which enables the tool to maintain compact size while still performing cutting operations effectively

Inventive Principle:

Principle #8Anti-weight (Counterweight)

2Volume of moving object

If a compact design is implemented to fit tight spaces, then the tool can operate in confined areas, but vibrations and shock increase

Engineering Contradiction:

Improvetool sizeVSAvoidvibrations and shock

Core Design Contradiction:

Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The counterweight mechanism is specifically designed to offset vibrations and shock forces generated during reciprocating motion. By positioning the counterweight to move in opposition to the spindle, the system balances dynamic forces, reducing harmful vibrations even in the compact configuration required for tight space operation

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The patent incorporates an elastic member positioned at the second end of the gear case that absorbs axial vibrations before they propagate through the tool structure. This cushioning element is pre-positioned to mitigate shock forces, allowing the compact tool design to operate in confined spaces without transmitting excessive vibrations to the user

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Ease of manufacture

If the gear case structure is simplified to reduce manufacturing complexity, then production cost decreases, but shock absorption capability is reduced

Engineering Contradiction:

Improvemanufacturing complexityVSAvoidaxial vibrations

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The gear case is divided into a first housing portion and a second housing portion, with the elastic member positioned at the second end. This segmentation allows the shock absorption function to be implemented as a discrete, easily manufactured component rather than requiring complex integrated structures, thus maintaining ease of manufacture while providing vibration damping

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The elastic member is integrated into the gear case structure as a simple, easily manufactured element that provides shock absorption. This approach uses a basic elastic component rather than complex damping mechanisms, maintaining manufacturing simplicity while effectively reducing axial vibrations through the elastic properties of the member

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 design achieves efficient motion translation with reduced vibrations and tool size, allowing for precise cutting operations in confined spaces.

Implementation Method 1

an elastic member positioned at the second end... configured to abut the clastic member to absorb shock due to axial vibrations during operation

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS12599978B2Reciprocating tool

Publication Date: 2026.04.14 MILWAUKEE ELECTRIC TOOL CORP

AI summary

A power tool includes: a housing having a handle configured to be grasped by a user; a motor supported by the housing and defining a motor axis; a driving gear rotated by the motor about the motor axis; a driven gear defining a rotation axis that is parallel to the motor axis, the driven gear engaging the driving gear to be rotated by the driving gear about the rotation axis; a crankshaft coupled to and rotatable with the driven gear; a counterweight having a first yoke coupled to the driven gear to translate rotation of the driven gear into reciprocating motion of the counterweight; and a spindle having a second yoke coupled to the crankshaft to translate rotation of the driven gear into reciprocating motion of the spindle, wherein the counterweight and the spindle reciprocate opposite one another.