Planetary Gearset Layout for Compact Marine Forward-Reverse Shifting

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Solution Overview

Problem

Existing marine propulsion transmissions face challenges such as difficult manufacturing and assembly of bevel gearsets, noisy shifting due to unsynchronized clutches, large installation dimensions, complex hydraulic systems, and significant power losses, which complicate integration and increase environmental susceptibility.

Innovation Solution

A transmission design utilizing a main and complementary planetary gearset that allows for forward and reverse rotation, with integrated brakes to engage these gearsets, enabling compact, efficient, and synchronized speed reduction and reversal, while maintaining a hydrodynamic gearcase shape.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If bevel gearset is used for speed reduction, then speed reduction function is achieved, but manufacturing difficulty and assembly complexity increase

Engineering Contradiction:

Improvespeed reductionVSAvoidmanufacturing difficulty

Core Design Contradiction:

SpeedVSEase of manufacture

Solution Approach 1:

The patent replaces the traditional bevel gearset with a planetary gearset, substituting one mechanical system with another that achieves the same speed reduction function but with superior manufacturability. The planetary gearset uses simpler cylindrical gears arranged in a compact configuration, eliminating the complex bevel gear geometry while maintaining the speed reduction capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If bevel gearset with dog tooth clutches is used, then forward and reverse function is achieved, but shifting noise and damage risk increase

Engineering Contradiction:

Improveforward and reverse functionVSAvoidshifting noise

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces dog tooth clutches with a different clutch mechanism that eliminates the punching noise during engagement. The new system uses a more gradual engagement method, possibly involving friction surfaces or a different tooth engagement geometry, that avoids the sudden impact and associated noise while still achieving reliable forward and reverse shifting.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If horizontally arranged idler shaft with bevel gear is used, then reversing function is achieved, but space occupation and installation complexity increase

Engineering Contradiction:

Improvereversing functionVSAvoidspace occupation

Core Design Contradiction:

Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The patent merges the reversing function directly into the planetary gearset by incorporating a reversing planetary gearset that shares common components with the forward gear planetary set. This integration eliminates the need for a separate horizontal idler shaft and its associated bevel gears, consolidating multiple functions into a single compact unit that reduces overall space requirements.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent transitions from a horizontal arrangement of idler shafts to a vertical or coaxial arrangement within the planetary gearset. By organizing the reversing mechanism in a different spatial dimension (using vertical stacks of planetary gears or coaxial arrangements), the design achieves the same reversing function while occupying significantly less horizontal space and allowing for more compact integration into the transmission housing.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

4Adaptability or versatility

If multi-disc clutches with large installation dimensions are used, then forward and reverse control is achieved, but transmission size and complexity increase

Engineering Contradiction:

Improveforward and reverse controlVSAvoidtransmission complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines the forward and reverse clutch functions into a single integrated planetary gearset system. Rather than using separate multi-disc clutches for each direction, the design uses a unified planetary arrangement where the same basic mechanism can produce both forward and reverse output by changing the engagement state of brake bands or clutch packs applied to different elements of the planetary set. This merging reduces the number of separate clutch assemblies and simplifies the overall transmission architecture.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS12552511B2Planetary gearset and a transmission with the planetary gearset

Publication Date: 2026.02.17 FORTL KAREL

AI summary

The planetary gearset has different areas of use. Transmissions are intended for example for marine propulsion device. A main planetary gearset that connects the input shaft to the output shaft so as to drive the output shaft into forward rotation. A complementary planetary gearset together with the main planetary gearset that connect the input shaft to the output shaft so as to drive the output shaft into reverse rotation. A forward brake engages the main planetary gearset in a forward gear wherein the main planetary gearset drives the output shaft into the forward rotation. A reverse brake engages the complementary planetary gearset in a reverse gear wherein the complementary planetary gearset together with the main planetary gearset drive the output shaft into the reverse rotation.