Compound Harmonic Gearbox Structure for Continuous Output Rotation

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Solution Overview

Problem

Existing compound harmonic gearboxes have a limited range of rotational motion, restricting their application in machinery requiring continuous output rotation.

Innovation Solution

A compound harmonic gearbox design featuring a first ground gear with mounting features, a flex spline, and a wave generator that allows the output flange to rotate completely around a stationary shaft, enabling continuous rotation through a combination of spur and bevel gears and support bearings, with the input shaft extending through axial and radial channels for rotational positioning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a traditional compound harmonic gearbox is designed with a fixed housing structure, then manufacturing and assembly are simplified, but the output rotation is limited to a restricted range

Engineering Contradiction:

Improveoutput rotation rangeVSAvoidhousing structure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The housing is divided into two separate ground gears (first ground gear and second ground gear) that can be independently manufactured and then assembled. This segmentation allows each ground gear to be produced using standard manufacturing processes while enabling the overall structure to accommodate continuous output rotation, thus resolving the contradiction between manufacturing simplicity and rotational versatility.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The output flange is positioned such that it rotates within the housing formed by the two ground gears, with the input shaft extending through the first ground gear. This nested configuration allows the output component to achieve continuous rotation while maintaining a compact overall structure, balancing adaptability with device complexity.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Adaptability or versatility

If the input shaft extends through the first ground gear, then continuous output rotation is enabled, but mounting and assembly become more complex

Engineering Contradiction:

Improvecontinuous rotation capabilityVSAvoidmounting and assembly

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The housing is segmented into two separate ground gears with the input shaft extending through the first ground gear. This segmentation allows the input shaft to pass through a dedicated pathway in the first ground gear, enabling continuous rotation while keeping the mounting features on only one component, thus facilitating assembly despite the extended shaft configuration.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first ground gear serves multiple functions: it forms part of the housing structure, provides a pathway for the input shaft extension, and incorporates mounting features for securing the assembly. This multi-functionality reduces the number of separate components needed, simplifying manufacturing and assembly while enabling continuous rotation.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Ease of manufacture

If only the first ground gear includes mounting features, then assembly is simplified, but structural symmetry is reduced

Engineering Contradiction:

Improveassembly simplicityVSAvoidstructural symmetry

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The housing structure deliberately employs asymmetry by placing mounting features only on the first ground gear rather than symmetrically on both ground gears. This asymmetric design simplifies assembly by providing a single location for mounting operations while the two ground gears remain structurally equivalent in terms of their gear functionality, thus resolving the contradiction between assembly simplicity and structural symmetry.

Inventive Principle:

Principle #4Asymmetry

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

This design enhances the gearbox's power density and efficiency, enabling broader applications in earth moving equipment, power tools, and other machinery by allowing continuous output rotation, thus expanding its utility beyond the limitations of traditional gearboxes.

Implementation Method 1

a wave generator within the housing that drives the flex spline

Methodology Applied

Scientific EffectMechanical Force: Mechanical Force

Implementation Method 2

an input gear that drives the wave generator, the input shaft extending through the first ground gear

Methodology Applied

Scientific EffectGear: Gear

Implementation Method 3

one or more input-shaft bearings are disposed in the input-shaft channel for rotational positioning of the input shaft

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS11371596B2Compound harmonic gearbox configured for continuous output rotation

Publication Date: 2022.06.28 HAMILTON SUNDSTRAND CORP

AI summary

Disclosed is a compound harmonic gearbox having: a first ground gear and a second ground gear being interconnected about a stationary shaft to form a housing, wherein only the first ground gear includes gearbox mounting features; an output flange partially encased within the housing; a flex spline within the housing that drives the output flange; a wave generator within the housing that drives the flex spline; an input shaft with an input gear that drives the wave generator, the input shaft extending through the first ground gear, wherein the output flange is configured to rotate completely around the stationary shaft by rotating the input shaft.