Marine Propulsion Transmission with Radial Planetary Gearsets
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Solution Overview
Problem
Current marine propulsion transmission systems face challenges in providing efficient and compact solutions for both forward and reverse gear operations with high power density, while maintaining durability and minimizing drag.
Innovation Solution
The transmission system incorporates forward and reverse planetary gearsets with integrated brakes, allowing for simultaneous power distribution to both gearsets, enabling the same speed reduction in both directions and utilizing a compact design within a gearcase housing that minimizes axial length and drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional transmission systems are used to provide both forward and reverse gear operations, then the system can achieve basic gear functionality, but the axial length increases and drag is minimized poorly
Solution Approach 1:
The patent combines forward and reverse planetary gearsets into a single integrated transmission unit with a common input shaft and shared structural components. The forward planetary gearset and reverse planetary gearset are merged such that they share the input shaft, carrier, and housing structure, reducing the overall axial length compared to separate forward and reverse transmission units.
Solution Approach 2:
The patent arranges the forward and reverse planetary gearsets in a radial configuration around the input shaft rather than in series along the axial direction. The forward planet gears and reverse planet gears are positioned at different radial angles, allowing power distribution in multiple directions simultaneously and minimizing axial length extension.
2Adaptability or versatility
If separate forward and reverse gear mechanisms are used, then gear functionality is achieved, but the device complexity and power density are reduced
Solution Approach 1:
The input shaft serves multiple functions simultaneously: it acts as the common input for both forward and reverse planetary gearsets, provides structural support for both gearsets, and enables power distribution to multiple outputs (forward drive, reverse drive, and neutral) through its integrated carrier design. This multi-functionality increases power density by eliminating redundant components.
Solution Approach 2:
The transmission system is segmented into functionally independent but structurally integrated modules: the forward planetary gearset, reverse planetary gearset, common input shaft, and shared housing. Each module can be designed and manufactured separately but combines into a compact unified system that achieves high power density through efficient space utilization.
3Ease of manufacture
If compact design is implemented to minimize axial length, then drag is reduced, but manufacturing complexity increases
Solution Approach 1:
The integrated transmission system is divided into modular components (forward planetary gearset, reverse planetary gearset, input shaft assembly, housing) that can be manufactured and assembled separately. This segmentation allows each component to be optimized for manufacturing while maintaining the compact integrated design, reducing overall manufacturing complexity despite the advanced geometry.
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 provides high power density, durability, and efficient gear operation in both forward and reverse modes, sustaining torque and speed requirements while maintaining a compact, hydrodynamically optimized shape.
Implementation Method 1
A forward planetary gearset connects the input shaft to the output shaft so as to drive the output shaft into forward rotation. A reverse planetary gearset connects the input shaft to the output shaft so as to drive the output shaft into reverse rotation.
Implementation Method 2
A forward brake engages the forward planetary gearset in a forward gear. A reverse brake engages the reverse planetary gearset in a reverse gear.
Data Source
AI summary
A transmission is for a marine propulsion device having an internal combustion engine that drives a propulsor for propelling a marine vessel in water. An input shaft is driven into rotation by the engine. An output shaft drives the propulsor into rotation. A forward planetary gearset that connects the input shaft to the output shaft so as to drive the output shaft into forward rotation. A reverse planetary gearset that connects the input shaft to the output shaft so as to drive the output shaft into reverse rotation. A forward brake engages the forward planetary gearset in a forward gear wherein the forward planetary gearset drives the output shaft into the forward rotation. A reverse brake engages the reverse planetary gearset in a reverse gear wherein the reverse planetary gearset drives the output shaft into the reverse rotation.