Low Cost Spin Actuators Using Star Compound Gear Trains
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Solution Overview
Problem
Existing rotary actuators face challenges with high cost, noise, wear, and performance-to-cost ratios, particularly in applications requiring low-cost, high torque density, and durability, such as orthotics and robotics, due to the inefficiencies of epicyclic gear trains which have high inertia, excess bearings, and centrifugal forces.
Innovation Solution
The development of a low-cost pancake actuator using a star compound gear train with fixed planet bearings in strong cross plates, a brushless DC motor, and high-quality plastic nylon gears to reduce noise and stress, enabling a compact, rugged, and scalable design with quick-change interfaces for mass production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If epicyclic gear trains are used in rotary actuators, then torque transmission is achieved, but cost increases and noise increases due to excess bearings and centrifugal forces
Solution Approach 1:
The patent removes the complex epicyclic gear train structure including excess bearings and centrifugal force-generating components, replacing it with a simplified gear arrangement that achieves torque transmission without the harmful elements. This extraction eliminates the source of high cost and noise while maintaining the essential torque transmission function.
Solution Approach 2:
The patent employs high-quality plastic nylon gears instead of expensive metal components, accepting that these plastic gears may have shorter service life but achieving significant cost reduction. This substitution directly addresses the cost issue while the high-quality plastic material maintains adequate durability for the application.
2Power
If epicyclic gear trains are used in rotary actuators, then torque transmission is achieved, but noise increases due to centrifugal forces and wear
Solution Approach 1:
The patent eliminates the epicyclic gear train structure that generates centrifugal forces and associated noise, replacing it with a simpler gear configuration that transmits torque without producing harmful noise levels. This directly removes the noise-generating mechanisms while preserving torque transmission.
Solution Approach 2:
By using high-quality plastic nylon gears instead of metal gears, the patent reduces noise generation from gear meshing and centrifugal forces. The plastic material inherently dampens noise while the high quality ensures adequate service life, addressing the noise issue effectively.
3Power
If traditional rotary actuators are designed for high torque density, then performance is improved, but cost increases reducing the performance-to-cost ratio
Solution Approach 1:
The patent uses high-quality plastic nylon gears to replace expensive metal components, achieving cost reduction while maintaining adequate torque density performance. The plastic gears are designed with high quality to ensure they meet performance requirements despite being less durable than metal alternatives.
Solution Approach 2:
The patent changes the material parameter from metal to high-quality plastic nylon, and optimizes the gear design parameters to achieve the required torque density at lower cost. This parameter change enables cost-effective production while maintaining performance.
4Productivity
If mass production and rapid assembly are implemented, then productivity increases, but manufacturing precision may deteriorate
Solution Approach 1:
The actuator is divided into modular components with standardized interfaces, enabling rapid assembly while maintaining precision through consistent manufacturing of standardized parts. The segmentation into discrete modules with defined interfaces allows for quality control at each stage.
Solution Approach 2:
The patent employs quick-change interfaces that are universal and standardized, allowing rapid assembly and disassembly without compromising precision. These standardized interfaces ensure consistent alignment and fit across multiple production cycles.
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 star compound gear train provides a cost-effective solution with improved torque density, reduced noise, and increased durability, enabling wide utilization in various applications while maintaining a high performance-to-cost ratio, suitable for mass production and rapid assembly in domains like orthotics and robotics.
Implementation Method 1
a brushless DC motor
Data Source
AI summary
An actuator is provided which includes a stationary frame; an output plate disposed within said stationary frame; a top plate; a stator disposed between said stationary frame and said top plate, said stator describing an annulus; a rotor disposed within the annulus of said stator; a principal bearing disposed between said stationary frame and said output plate; a pinion gear; and a star gear which meshes with said pinion gear.