Direct Drive Exercise Machine Using Nested Planetary Gears
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Solution Overview
Problem
Current elliptical exercise machines require large spaces due to complex drive mechanisms involving pulleys, belts, and cables, which increase the size of the rotating elements and necessitate larger covers for safety, highlighting a need for a more compact and efficient motion transfer system.
Innovation Solution
The implementation of a direct drive mechanism using a crank shaft with two planetary gear sets, where the first planetary gear set is connected to the second, and both are linked to a flywheel, allowing for efficient rotation and compact packaging by eliminating the need for additional pulleys or belts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional drive mechanisms with pulleys, belts, and cables are used, then motion transfer is achieved, but the size of the machine increases and safety covers become larger
Solution Approach 1:
The patent combines multiple drive functions into a single integrated planetary gear system. The first and second planetary gear sets are coupled together with their planet carriers connected, allowing the system to perform both motion transfer and resistance control in one compact unit, eliminating the need for separate pulleys, belts, and cables
Solution Approach 2:
The planetary gear sets are nested within each other, with the second planetary gear set positioned inside the first. The planet carriers are coupled together, creating a compact nested arrangement that significantly reduces the overall volume of the drive mechanism compared to traditional distributed components
2Reliability
If traditional drive mechanisms are used, then motion transfer is achieved, but the rotating elements become larger requiring larger safety covers
Solution Approach 1:
The patent merges the flywheel function with the planetary gear system by integrating it as part of the second planetary gear set. This consolidation reduces the overall footprint of rotating elements, allowing for smaller safety covers while maintaining protective functionality
Solution Approach 2:
The nested arrangement of planetary gear sets places rotating elements concentrically, minimizing the radial footprint. This nested configuration allows safety covers to be smaller while still enclosing all moving parts effectively
3Volume of moving object
If planetary gear sets are used, then compact arrangement is achieved, but gear meshing complexity increases
Solution Approach 1:
The drive mechanism is segmented into two distinct planetary gear sets, each with its own sun gear, planet gears, and ring gear. This segmentation allows for modular manufacturing and assembly, where each gear set can be produced and tested separately before being coupled together, reducing overall manufacturing complexity despite the compact final arrangement
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 a compact arrangement of driven elements, reducing the size of the support structure and enhancing safety by simplifying the packaging of the exercise machine's components, while maintaining effective motion transfer and resistance control.
Implementation Method 1
a first planetary gear set including a first sun gear rotatably mounted on the crank shaft, a first planet carrier mounted on the crank shaft and secured thereto for rotation with the crank shaft, a first planet gear rotatably mounted on the first planet carrier and meshing with the first sun gear, and a first ring gear encircling and meshing with the first planet gear
Implementation Method 2
a flywheel rotatably mounted on the crank shaft and being operatively connected to the second planetary gear set such that output rotation of the second planetary gear set causes rotation of the flywheel
Data Source
AI summary
An exercise machine includes a support structure, a crank shaft rotatably mounted on the support structure, a first planetary gear set operatively coupled to the crank shaft so that the crank shaft provides an input for the first planetary gear set, a second planetary gear set operatively coupled to the first planetary gear set so that an output of the first planetary gear set provides an input for the second planetary gear set, and a flywheel rotatably operatively coupled to the second planetary gear set so that an output of the second planetary gear set rotates the flywheel.