Virtual Elliptical Drive Nutation Mechanism
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Solution Overview
Problem
Wobble plate drive systems face challenges in achieving high gear ratios within a small volume due to issues like disengagement, vibration, and inefficiency caused by friction and forces involved.
Innovation Solution
A mechanical virtual elliptical drive system comprising an input motor, wobble plate, stator gear, and output plate, where the wobble plate nutates around the stator gear, and the face teeth engage with output teeth, allowing for a high gear ratio with reduced friction through rolling contact and a frustoconical surface design that aligns the center of mass with the vertex, minimizing eccentric forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
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 the mechanism suffers from disengagement, vibration, and inefficiency due to friction
Solution Approach 1:
The patent employs a spherical interface between the wobble plate and stator gear, where the wobble plate has a spherical surface that contacts the stator gear's spherical interface. This curved surface geometry ensures continuous point contact throughout the nutation cycle, preventing disengagement and eliminating the need for additional retention mechanisms, thereby achieving reliable high-ratio reduction in compact volume
2Speed
If traditional wobble plate drive is used, then compact high gear ratio is achieved, but unacceptable levels of vibration occur
Solution Approach 1:
The patent incorporates a counterweight mechanism where the wobble plate's center of mass is positioned offset from its geometric center, creating a balancing mass that counteracts the eccentric forces generated during nutation. This counterbalancing approach reduces vibration amplitudes and eliminates the need for complex external balancing mechanisms
3Volume of moving object
If wobble plate drive mechanism is implemented, then high gear ratio in small volume is achieved, but inefficiency due to friction occurs
Solution Approach 1:
The patent replaces traditional sliding contact mechanics with rolling contact mechanics by designing the wobble plate and stator gear interfaces with spherical surfaces and rolling element bearings. This substitution transforms the dominant friction mechanism from sliding friction to rolling friction, dramatically reducing energy losses and improving overall drive efficiency while maintaining the compact high-ratio design
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 enables efficient transfer of motion, achieving gear ratios in the hundreds or thousands with reduced friction and vibration, effectively increasing torque in a compact design.
Implementation Method 1
a rounded protrusion extending from the substantially flat surface; wherein the rounded protrusion is configured to engage with the substantially flat surface
Implementation Method 2
allowing for a high gear ratio with reduced friction through rolling contact
Implementation Method 3
a frustoconical surface design that aligns the center of mass with the vertex, minimizing eccentric forces
Data Source
Figure 1
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AI summary
A mechanical virtual elliptical drive (10), including an input motor (12), a wobble plate (14), a stator gear (16), and an output plate (18). The input motor may have a rotation axis (20), a substantially flat surface (36), and a rounded protrusion (38, 40) extending from the flat surface. The wobble plate may have a wobble axis (22) disposed at a non-zero angle relative to the rotation axis. The rounded protrusion of the motor may engage a substantially flat face (24) of the wobble plate, thereby causing the wobble plate to nutate around the stator gear.