Double-Pinion Planetary Gear for Counter-Rotating Marine Propellers
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Solution Overview
Problem
Existing marine propulsion units face challenges in efficiency, performance, lifetime, and cost, particularly in systems with dual propellers rotating in opposite directions, where improvements are needed to enhance energy efficiency, maneuverability, and reduce appendage drag.
Innovation Solution
A marine propeller propulsion unit utilizing a double-pinion planetary gear, where a sun gear is connected to an input shaft, a ring gear to a front propeller, and a planet carrier to a rear propeller, allowing for a high gear ratio and compact design, with a single electric propulsion motor directly connected to the input shaft, and optionally using helical gears to cancel axial forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a high-speed motor is used to drive dual propellers, then power density and speed are improved, but torque distribution control becomes difficult
Solution Approach 1:
A planetary gear mechanism is introduced as an intermediary between the high-speed motor and the dual propellers. The sun gear connects to the motor, while planet gears and ring gear distribute torque to front and rear propellers respectively. This mechanical intermediary automatically achieves differential torque distribution based on gear ratios, solving the control difficulty while maintaining high motor speed operation
2Volume of moving object
If a planetary gear mechanism is used to achieve high gear ratio, then compact size is improved, but manufacturing complexity increases
Solution Approach 1:
The planetary gear mechanism is divided into modular components: sun gear, planet gears, ring gear, and carrier. Each component can be manufactured separately using standard gear manufacturing processes, then assembled together. This segmentation reduces manufacturing complexity while achieving the compact high gear ratio design
3Adaptability or versatility
If dual propellers rotate in opposite directions for improved maneuverability, then performance is improved, but system complexity increases
Solution Approach 1:
The planetary gear mechanism inherently provides asymmetric torque distribution to the dual propellers. By configuring the ring gear and planet carrier connections, the system automatically generates opposite rotation directions with different torque characteristics. This asymmetric mechanical design achieves superior maneuverability while maintaining relatively simple structure compared to independent motor control systems
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 solution achieves increased efficiency by providing a higher torque to the front propeller, reduced appendage drag, and lower operational costs through a compact, submerged design, with improved maneuverability and performance.
Implementation Method 1
A marine propeller propulsion unit comprises a double-pinion planetary gear for driving a front and a rear propeller by means of an input shaft. A sun gear is adapted to be connected to the input shaft, a ring gear is adapted to be connected to the front propeller, and a planet carrier is adapted to be connected to the rear propeller.
Data Source
AI summary
A marine propeller propulsion unit has a double-pinion planetary gear for driving a front and a rear propeller by means of an input shaft. A sun gear is adapted to be connected to the input shaft, a ring gear is adapted to be connected to the front propeller, and a planet carrier is adapted to be connected to the rear propeller.