Reciprocating Power Tool Counterbalance for No-Load Vibration

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Solution Overview

Problem

Reciprocating power tools with large saw blades experience significant no-load vibration due to increased mass, leading to reduced user comfort and efficiency, as existing balancing components fail to effectively mitigate this issue.

Innovation Solution

A reciprocating power tool design incorporating a balancing component with a mass ratio greater than 1.05, where the product of the balancing component's mass and movement distance exceeds the product of the reciprocating assembly's mass and movement distance, along with a transmission assembly and eccentric member, to counteract the motion and reduce vibration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a large saw blade with greater mass is used for cutting operations, then cutting capability is improved, but no-load vibration significantly increases

Engineering Contradiction:
Improvecutting capabilityVSAvoidno-load vibration
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies the counterweight principle by introducing a balancing component with mass M2 that moves in opposition to the reciprocating assembly. The balancing component generates a counterbalancing force through its motion, where the product M2·L2 is designed to be greater than M1·L1 (with ratio >1.05), creating an opposing force that cancels out the harmful vibrations generated by the large-mass saw blade during no-load operation.

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

Solution Approach 2:

The patent changes the mass and motion parameters of the balancing component relative to the reciprocating assembly. Specifically, it designs the balancing component with a mass M2 and motion distance L2 such that the ratio (M2·L2)/(M1·L1) exceeds 1.05, optimizing the counterbalancing effect. This parameter adjustment allows the system to effectively reduce no-load vibration while maintaining cutting performance with large saw blades.

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

The solution significantly reduces no-load vibration by up to 40% compared to existing designs, enhancing user experience and tool stability, even when using large-mass saw blades, and optimizes loaded vibration by sacrificing no-load vibration.

Implementation Method 1

a balancing component for balancing a motion of the reciprocating assembly. A maximum distance the centroid of the reciprocating assembly moves is a first distance L1; a maximum distance the centroid of the balancing component moves is a second distance L2; the mass of the reciprocating assembly is a first mass M1, and the mass of the balancing component is a second mass M2

Methodology Applied
Scientific EffectInertia: Inertia

Data Source

PatentEP4523825A1Reciprocating power tool
Publication Date: 2025.03.19 NANJING CHERVON IND
  • EP4523825A1 patent drawingFigure 1
  • EP4523825A1 patent drawingFigure 2
  • EP4523825A1 patent drawingFigure 3

AI summary

A reciprocating power tool (100) includes a housing (10), a power assembly (20) including an electric motor (21), a transmission assembly (32) connected to the power assembly (20), a reciprocating assembly (31) connected to the transmission assembly (32) performing a reciprocating motion and mountable with a working accessory (50) for an operation and a balancing component (331) for balancing a motion of the reciprocating assembly (31). A maximum distance the centroid (C1) of the reciprocating assembly (31) moves is a first distance L1, a maximum distance the centroid (C2) of the balancing component (331) moves is a second distance L2, the mass of the reciprocating assembly (31) is a first mass M1 and the mass of the balancing component (331) is a second mass M2. The ratio of a product M2·L2 of the second mass M2 and the second distance L2 to a product M1·L1 of the first mass M1 and the first distance L1 is greater than 1.05.