Wave Gear Motor Integration for Compact Flexspline Drives

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Solution Overview

Problem

Existing geared motor units require significant installation space due to the length needed for the flexspline deformation, making them unsuitable for applications with space constraints, and existing solutions fail to efficiently utilize available space.

Innovation Solution

A compact geared motor unit design integrates the motor into the transmission, utilizing unused space within the wave gearbox, with a wave gearbox comprising a flexspline, circular spline, and wave generator, and incorporating a thermally conductive stator housing for efficient heat dissipation and flexible element arrangement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the flexspline is given sufficient axial length to maintain deformation and prevent excessive angular deformation, then reliability is improved, but volume increases

Engineering Contradiction:
Improveflexspline deformation stabilityVSAvoidgearbox volume
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The motor is integrated into the unused space within the wave gearbox, merging two separate components (motor and gearbox) into a single compact unit. This eliminates the need for separate motor housing and reduces overall volume while maintaining the required flexspline axial length for reliable operation

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The motor is nested within the gearbox structure, specifically utilizing the unused space created by the flexspline deformation zone. The stator and rotor are positioned within the gearbox volume, allowing the motor to be contained within the existing gearbox boundaries rather than requiring additional external space

Inventive Principle:
Principle #7Nested doll (Nesting)

2Volume of moving object

If the motor is integrated into the gearbox using unused space, then volume is reduced, but device complexity increases

Engineering Contradiction:
Improvegeared motor unit volumeVSAvoidintegration complexity
Core Design Contradiction:
Volume of moving objectVSDevice complexity

Solution Approach 1:

The gearbox housing serves multiple functions: it contains the wave gear mechanism, provides structural support, and acts as the motor housing. The stator housing is formed as an integral part of the gearbox structure, eliminating the need for separate motor housing and reducing overall complexity despite the integrated design

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Temperature

If the stator housing is made thermally conductive for efficient heat dissipation, then temperature control is improved, but weight increases

Engineering Contradiction:
Improveheat dissipation efficiencyVSAvoidstator housing weight
Core Design Contradiction:
TemperatureVSWeight of stationary object

Solution Approach 1:

The stator housing is made from a thermally conductive material that provides efficient heat dissipation. The material selection balances thermal conductivity requirements with weight considerations, allowing the integrated motor-gearbox unit to dissipate heat effectively without excessive weight increase

Inventive Principle:
Principle #40Composite materials

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 design allows for efficient torque translation and versatile application in space-constrained environments, reducing installation space requirements while maintaining performance through efficient heat management and flexible component arrangement.

Implementation Method 1

The flexspline can typically deform, for example, by means of a rolling bearing

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

incorporating a thermally conductive stator housing for efficient heat dissipation

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP3625880B1Transmission motor unit
Publication Date: 2023.10.11 SIEMENS AG
  • EP3625880B1 patent drawingFigure 1
  • EP3625880B1 patent drawingFigure 2
  • EP3625880B1 patent drawingFigure 3

AI summary

The invention relates to a geared motor unit (1) comprising a motor (12, 14) that includes a stator (12) and a rotor (14), further comprising a gear unit (22, 24, 26) that includes a first element (22), a second element (24) and a third element (26), one part of the motor (12, 14) being connected to the third element (26), the other part of the motor (12, 14) being connected to the first element (22) of the gear unit, and an element of the gear unit (22, 24, 26) being connected to ground (40).