Miniature Laminar Gear Transmission Torque Density

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Solution Overview

Problem

Commercially available miniature gearboxes have intermittent torque ratings that require further reduction and lack sufficient torque density, leading to larger-than-necessary designs due to material strengths and design complexities, making it difficult to achieve high torque outputs in compact spaces.

Innovation Solution

A compact gearbox design utilizing a lamellar structure with integrated 3D printed planetary and spur gear stages, allowing for high torque density and seamless integration, achieved through additive manufacturing such as direct metal laser sintering, which enables the gearbox to be produced in a compact form with multiple components housed within each section.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If standard manufacturing techniques are used to produce compact gearboxes, then material strengths and design features (hub dimensions, shaft sizes) are constrained, but the gearbox size increases and torque density decreases

Engineering Contradiction:

Improvegearbox sizeVSAvoidtorque density

Core Design Contradiction:

Volume of moving objectVSQuantity of substance

Solution Approach 1:

The patent implements a nested planetary gear configuration where multiple planet gears are arranged concentrically around a sun gear within a compact housing. The planet gears are positioned in radial slots that allow them to mesh with both the sun gear and the annulus, creating a dense packing arrangement that maximizes torque density while minimizing overall gearbox volume.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The invention utilizes three-dimensional spatial arrangement by stacking gear stages vertically and arranging planetary gears in multiple radial positions. The housing incorporates internal cavities and recesses that allow gears to be positioned in non-planar configurations, effectively using vertical and radial dimensions to pack more components into a smaller footprint without increasing the external envelope significantly.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Strength

If additional design features (hub dimensions, shaft sizes, housing) are added to commercial gears, then material strength requirements are met, but device complexity and overall size increase

Engineering Contradiction:

Improvematerial strengthVSAvoiddesign complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent integrates the housing, mounting features, and gear support structures into a unified compact design. The housing incorporates integrated bearing mounts, shaft supports, and gear retention features directly into its structure, eliminating the need for separate components. This merging of functions reduces the number of parts and assembly steps while maintaining the necessary structural strength and material properties.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If separate housings are used for gear components, then component protection and mounting are achieved, but the overall gearbox size increases

Engineering Contradiction:

Improvecomponent protectionVSAvoidgearbox size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent employs a nested housing structure where internal cavities and recesses are formed within the main housing body to accommodate gear stages. Smaller protective chambers are positioned within larger housing sections, allowing multiple gear stages to be enclosed and protected within a single compact housing envelope rather than requiring separate housings for each component.

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 compact gearbox achieves high torque density, enabling applications requiring high torque outputs in confined spaces, such as prosthetic fingers, with a torque density of at least 0.15 Nm/m3, and allows for flexible integration without the need for separate housings, overcoming the limitations of traditional manufacturing techniques.

Implementation Method 1

direct metal laser sintering (DMSL) is used to manufacture the various components of the gearbox

Methodology Applied

Scientific EffectLaser sintering: Selective Laser Sintering

Implementation Method 2

direct metal laser sintering (DMSL) is used to manufacture the various components of the gearbox

Methodology Applied

Scientific EffectLaser heating: Laser

Data Source

PatentUS10794453B2High torque density miniature laminar gear transmission

Publication Date: 2020.10.06 COLORADO SCHOOL OF MINES

AI summary

A miniturized laminar gear box possessing high torque densities and methods of manufacturing the same. The high torque density is possible by directing the output shaft of the planetary stages through the sun gear and behind the input shaft. This allows the input shafts of the planetary stages to face towards the interior of the gearbox and provides a rotary shaft for the spur stages housed in between the planetary stages.