Impact Tool Ball-Groove Mechanism for High-Torque Handling

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Solution Overview

Problem

Existing impact tools face challenges in achieving high torque output while maintaining ergonomic design and efficient power transmission, often resulting in complex mechanisms that are cumbersome and inefficient.

Innovation Solution

The impact tool incorporates a unique ball groove design on the main shaft and impact block, with specific included angles and a rolling ball mechanism, along with an optimized elastic element, to enhance torque output and ergonomic handling, while utilizing a compact motor and transmission assembly for efficient power delivery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a complex impact mechanism is used to achieve high torque output, then the torque output is improved, but the device complexity increases making the mechanism cumbersome

Engineering Contradiction:
Improvetorque outputVSAvoidmechanism complexity
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The impact mechanism is divided into separate functional components: an impactor assembly that generates impact forces and a separate output assembly that delivers rotary motion. This segmentation allows each component to be optimized independently, reducing overall complexity while maintaining high torque output capability through coordinated operation of simpler parts

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent employs dynamic elements including a rotating impactor that can be actuated in multiple directions (first and second directions), and a ball groove mechanism with specific included angles (α < β) that enables dynamic ball positioning. These dynamic features allow the system to generate high impact forces through controlled motion rather than complex static mechanisms

Inventive Principle:
Principle #15Dynamics

2Productivity

If the ball groove included angle α is reduced to improve power transmission, then the power transmission efficiency is improved, but the manufacturing precision requirements increase

Engineering Contradiction:
Improvepower transmission efficiencyVSAvoidball groove angle precision
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent specifies particular parameter ranges for the ball groove included angles (α < 117° and β > 118°) to optimize power transmission efficiency. By defining these parameters within specific ranges rather than requiring exact precise values, the design achieves high power transmission while allowing for manufacturing tolerances, thus reducing the stringency of precision requirements

Inventive Principle:
Principle #35Parameter changes

3Power

If the impact frequency is increased to improve torque, then the torque output is improved, but the ergonomic handling deteriorates due to increased vibration

Engineering Contradiction:
Improvetorque outputVSAvoidergonomic handling
Core Design Contradiction:
PowerVSEase of operation

Solution Approach 1:

The ball groove mechanism acts as an intermediary between the high-frequency impact generator and the output assembly. The ball grooves with specific included angles guide and filter the impact forces, converting high-frequency impacts into smoother rotary motion. This intermediary mechanism maintains high torque output while reducing transmitted vibrations that would affect ergonomic handling

Inventive Principle:
Principle #24Intermediary (Mediator)

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 achieves high torque output exceeding 700 foot-pounds with a compact design, improved power transmission efficiency, and ergonomic handling, reducing user fatigue and enhancing operational efficiency.

Implementation Method 1

a rolling ball connecting the main shaft to the impact block

Methodology Applied
Scientific EffectRolling contact: Ball

Implementation Method 2

an elastic element that provides a force for the impact block to approach the hammer anvil

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4454816B1Impact tool
Publication Date: 2025.07.02 NANJING CHERVON IND
  • EP4454816B1 patent drawingFigure 1
  • EP4454816B1 patent drawingFigure 2
  • EP4454816B1 patent drawingFigure 3

AI summary

Provided is an impact tool. The impact tool includes an output shaft (400) for outputting torque, where the tightening torque of the output shaft (400) to a workpiece is greater than or equal to 750 N.m; and an impact assembly (300) that provides an impact force to the output shaft (400). A main shaft ball groove (311) includes a first ball groove (3111) that extends spirally about a main shaft axis (301) and is concave on an outer surface and a second ball groove (3112) that extends spirally about the main shaft axis (301) and is concave on the outer surface. An impact ball groove (321) includes a third ball groove (3211) that mates with the first ball groove (3111) to accommodate the rolling ball (350) and a fourth ball groove (3212) that mates with the second ball groove (3112) to accommodate the rolling ball (350). The included angle α between the first ball groove (3111) and the second ball groove (3112) is less than the included angle β between the third ball groove (3211) and the fourth ball groove (3212).