Self-aligning wobble plate drive without supporting shaft

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Solution Overview

Problem

Wobble plate drive mechanisms face challenges in achieving high gear ratios within a small volume due to issues like disengagement, binding, over-constraint, and inefficiency caused by friction, as existing designs often require a supporting shaft or fulcrum that introduces limitations.

Innovation Solution

A self-aligning wobble plate drive system without a supporting shaft or fulcrum, featuring an input plate, a stator gear with a central axis, a wobble plate with a non-zero wobble angle, and an output plate, where the wobble plate engages with the stator and output plates in a self-aligning manner to maintain constant wobble angle during nutation, utilizing complementary frustoconical surfaces to prevent eccentric forces and ensure alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a supporting shaft or fulcrum is used in the wobble plate drive, then the mechanism is constrained and guided, but the system becomes over-constrained leading to binding and friction

Engineering Contradiction:
Improvealignment stabilityVSAvoidfriction loss
Core Design Contradiction:
Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The patent removes the supporting shaft or fulcrum from the wobble plate drive mechanism. By extracting this constraint element, the system eliminates the over-constraint that causes binding and friction, allowing the wobble plate to move freely while maintaining alignment through the gear tooth engagement alone.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The wobble plate drive system achieves self-alignment through the geometric relationship between the gear teeth and the wobble plate geometry. The system serves its own alignment function without external support structures, using the inherent geometry of the meshing teeth to maintain proper orientation during nutation.

Inventive Principle:
Principle #25Self-service

2Reliability

If the wobble plate is constrained by a supporting shaft, then the gear teeth remain in alignment, but the mechanism experiences disengagement and binding

Engineering Contradiction:
Improvegear tooth alignmentVSAvoidmechanism smoothness
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The supporting shaft that causes disengagement and binding is removed from the system. The wobble plate operates without this external constraint, allowing smooth operation while the gear tooth geometry itself maintains alignment reliability.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using a supporting shaft to maintain alignment, the patent inverts the approach by using the gear tooth engagement geometry to provide alignment. The alignment function is transferred from the supporting structure to the meshing teeth themselves.

Inventive Principle:
Principle #13The other way round (Inversion)

3Stability of the object's composition

If a traditional wobble plate drive with supporting shaft is used, then the structure is stable, but the volume is increased and efficiency is reduced due to friction

Engineering Contradiction:
Improvestructural stabilityVSAvoidfriction loss
Core Design Contradiction:
Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The supporting shaft is extracted from the system, eliminating the source of friction and energy loss. The structural stability is maintained through the precision gear tooth engagement and the inherent geometry of the wobble plate mechanism without the need for additional support structures.

Inventive Principle:
Principle #2Taking out (Extraction)

4Ease of operation

If the wobble plate is supported by a shaft or fulcrum, then the mechanism is guided, but binding and over-constraint occur

Engineering Contradiction:
ImproveguidanceVSAvoidmechanism reliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The supporting shaft or fulcrum is removed from the system. The wobble plate is no longer guided by external support structures, eliminating the over-constraint that causes binding. Guidance is achieved through the gear tooth engagement geometry alone.

Inventive Principle:
Principle #2Taking out (Extraction)

Data Source

PatentEP3399212B1Self-aligning virtual elliptical drive
Publication Date: 2023.06.14 THE BOEING CO
  • EP3399212B1 patent drawingFigure 1
  • EP3399212B1 patent drawingFigure 2~3
  • EP3399212B1 patent drawingFigure 4

AI summary

A self-aligning wobble plate drive (10, 110, 210), including a stator gear (16, 116), a wobble plate (14, 114, 214), and an output plate (118). The stator gear has a central stator axis (54, 154) and a plurality of stator teeth (32, 132). The wobble plate has a wobble axis (22, 122, 222), a plurality of face teeth (28, 128), and a plurality of wobble teeth (30, 130), and is disposed such that the wobble axis is at a non-zero wobble angle relative to the stator axis. The output plate includes a plurality of output teeth (134) and is substantially aligned with the stator axis. At least two of the pluralities of teeth are configured to engage with each other in a self-aligning manner such that as the wobble plate nutates around the stator gear, the wobble angle remains constant.