Constant Torque Module with Directional Buffer Units

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Solution Overview

Problem

Conventional power tools face challenges in controlling torque output for both tightening and loosening operations, especially under high rotational speed, leading to potential damage and uneven stress distribution, and are costly to manufacture due to precise structural requirements.

Innovation Solution

A constant torque module comprising a transmission ring member, buffer units, internal and external shaft members, and drive blocks that allow for different torque outputs in clockwise and counterclockwise directions, maintaining high rotational speed and reducing manufacturing costs through simplified design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If pneumatic tools utilize oil pressure or planetary gear reduction mechanism to control torque, then torque control is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:
Improvetorque controlVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The torque control mechanism is segmented into two independent buffer units (first and second buffer units) with different buffer forces, allowing separate control of clockwise and counterclockwise torque without complex integrated systems. Each buffer unit independently manages torque in one rotational direction.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different buffer forces are applied at different locations (first buffer unit vs. second buffer unit) to achieve different torque magnitudes for clockwise and counterclockwise rotation. The third buffer unit provides additional localized torque adjustment capability.

Inventive Principle:
Principle #3Local quality

2Reliability

If conventional torque control mechanisms are used, then torque control is improved, but rotational speed decreases leading to poor working efficiency

Engineering Contradiction:
Improvetorque controlVSAvoidworking efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

Buffer units are introduced as intermediary elements between the output shaft and the tool head to control torque. These buffer units provide torque control through elastic deformation rather than mechanical friction or hydraulic resistance, minimizing energy loss and maintaining high rotational speed.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of operation

If arch-shaped sections with different striking portions are used, then different torques in different directions are achieved, but manufacturing cost increases due to high structural accuracy requirements

Engineering Contradiction:
Improvetorque differentiationVSAvoidmanufacturing cost
Core Design Contradiction:
Ease of operationVSEase of manufacture

Solution Approach 1:

Instead of requiring precise geometric shapes (arch-shaped sections), the invention changes the parameter of buffer force by using different buffer unit configurations and pre-compressed spring forces. This allows torque differentiation through easily adjustable mechanical parameters rather than precision machining.

Inventive Principle:
Principle #35Parameter changes

4Force

If torque is increased for tightening, then tightening force is improved, but risk of damage to fasteners increases

Engineering Contradiction:
Improvetightening forceVSAvoidfastener damage
Core Design Contradiction:
ForceVSObject-affected harmful factors

Solution Approach 1:

The buffer units provide automatic feedback control of torque through elastic deformation. When the tightening force reaches the buffer force limit, the buffer unit deforms elastically, automatically limiting further torque increase and preventing fastener damage without requiring complex sensing systems.

Inventive Principle:
Principle #23Feedback

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 module achieves consistent torque control at high rotational speeds, reducing manufacturing costs while ensuring efficient operation and preventing damage to fasteners, with clockwise torque being about one-quarter of counterclockwise torque, and can be adapted to various power tools.

Implementation Method 1

two buffer units, each of the two buffer units being disposed in a part of one of the two accommodations such that each of the two accommodations remains a receiving space

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP4467291B1Constant torque module for power tool
Publication Date: 2025.07.02 HO CHUAN CHENG
  • EP4467291B1 patent drawingFigure 1
  • EP4467291B1 patent drawingFigure 2
  • EP4467291B1 patent drawingFigure 3

AI summary

A constant torque module (1, 1a, 1b) for a power tool (2) includes a transmission ring member (10, 10a, 10b), which has a core shaft (14), two accommodations (16) and two drive blocks (18), two buffer units (20) disposed respectively in parts of the accommodations (16) such that each of the two accommodations (16) remains a receiving space (17), an internal shaft member (30), which has two inner protrusions (32) extending into the receiving spaces (17) and being contactable with the two buffer units (20) respectively, a shaft notch (34) engaged with the core shaft (14), and a shaft rod (35) having an engagement portion (38), and an external shaft member (40) including two outer protrusions (42) contactable with the two drive blocks (18) respectively, and a shaft tube (44) having an engagement notch (49) engaged with the engagement portion (38) of the internal shaft member (30). As such, the constant torque module (1, 1a, 1b) outputs different torques when it rotates in reverse directions and has the advantages of high rotational speed, good working efficiency and low manufacturing cost.