Balanced Eccentric Gear Design for High Ratio Wobble Plate Drive

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Solution Overview

Problem

Existing wobble plate drive mechanisms face challenges in achieving high gear ratios within a small volume due to disengagement and unacceptable vibrations, making efficient and effective systems elusive.

Innovation Solution

The proposed wobble plate drive system includes a stator with a central axis and upper surface teeth, a wobble plate with a non-zero angled wobble axis, and an output gear, where the wobble plate nutates around the stator, engaging lower and upper teeth with stator and output teeth respectively, utilizing compound involute shapes to manage eccentric forces and maintain alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a wobble plate drive mechanism is used to achieve high gear ratio in small volume, then the gear ratio and compactness are improved, but disengagement and unacceptable vibrations occur

Engineering Contradiction:
Improvegear ratioVSAvoidmechanism stability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The gear system is divided into multiple gears with different tooth counts (first gear with N teeth, second gear with N+1 teeth, third gear with M teeth) rather than using a single wobble plate interface. This segmentation allows each gear to handle specific force vectors, preventing disengagement while achieving the desired high gear ratio through the combined gear ratio of N:(N+1)×M:1

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different gears are positioned at specific locations around the rotor to handle different force components. The first gear engages at one location to prevent disengagement in one direction, the second gear engages at another location to prevent disengagement in the opposite direction, and the third gear provides additional gear reduction. This localized arrangement of gears with specific tooth counts at specific positions ensures reliable force transmission without vibrations

Inventive Principle:
Principle #3Local quality

2Device complexity

If fewer gears are used to reduce device complexity, then the mechanism simplicity is improved, but disengagement and vibrations increase

Engineering Contradiction:
Improvenumber of gearsVSAvoidmechanism stability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The gear system is divided into multiple gears with different tooth counts (first gear with N teeth, second gear with N+1 teeth, third gear with M teeth) rather than using a single wobble plate interface. This segmentation allows each gear to handle specific force vectors, preventing disengagement while achieving the desired high gear ratio through the combined gear ratio of N:(N+1)×M:1

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different gears are positioned at specific locations around the rotor to handle different force components. The first gear engages at one location to prevent disengagement in one direction, the second gear engages at another location to prevent disengagement in the opposite direction, and the third gear provides additional gear reduction. This localized arrangement of gears with specific tooth counts at specific positions ensures reliable force transmission without vibrations

Inventive Principle:
Principle #3Local quality

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 configuration allows for high gear ratios, such as 33,000:1, within a compact volume, ensuring non-eccentric motion and enabling precise motor control, overcoming previous inefficiencies and vibration issues.

Implementation Method 1

Electric motors create mechanical energy from electromagnetic energy. An alternating current (AC) motor generally includes a rotor and a stationary stator. The stationary stator usually has windings of electrical wires which carry an alternating current which produces a rotating magnetic field.

Methodology Applied
Scientific EffectElectromagnetic energy conversion: Electromagnetic Induction

Implementation Method 2

utilizing compound involute shapes to manage eccentric forces and maintain alignment

Methodology Applied
Scientific EffectCompound involute geometry: Geometry

Data Source

PatentEP3096444B1Balanced eccentric gear design and method
Publication Date: 2020.10.28 THE BOEING CO
  • EP3096444B1 patent drawingFigure 1
  • EP3096444B1 patent drawingFigure 2
  • EP3096444B1 patent drawingFigure 3~4

AI summary

A wobble plate drive system may include a stator having a central axis, an upper surface perpendicular to the central axis, and a plurality of stator teeth disposed on the upper surface. The system may further include a wobble plate having a wobble axis disposed at a non-zero angle relative to the central axis, a lower wobble surface perpendicular to the wobble axis, and an upper wobble surface perpendicular to the wobble axis. A plurality of lower wobble teeth may be disposed on the lower wobble surface and a plurality of upper wobble teeth may be disposed on the upper wobble surface. The system may include an output gear having an output axis substantially aligned with the central axis and a lower surface perpendicular to the output axis. A plurality of output teeth may be disposed on the lower surface. The wobble plate may be configured to rotate as it nutates around the stator.