Azimuthing Drive Gearbox Variable Ratio for Marine Propulsion
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Solution Overview
Problem
Conventional azimuthing drive systems for marine propulsion face inefficiencies due to mismatched optimum operating speed and load ranges between engines and propulsors, making it difficult to fully utilize both components for optimal performance.
Innovation Solution
The azimuthing drive system incorporates a propulsion pod with a propulsor that can swivel about a horizontal axis, driven by a vertical shaft, and includes a gearbox connected to a diesel engine and an electric motor. The electric motor can drive the gearbox directly or via a coaxial, coplanar, or parallel shaft, allowing for sharing or dividing propulsion loads between the engine and motor, and an energy management system controls the modes of operation to optimize performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional gearing is used to match engine speed to propulsor speed, then the engine can operate at its optimum speed range, but the propulsor cannot fully utilize its optimum speed and loading ranges
Solution Approach 1:
The patent applies dynamics by making the gear ratio variable rather than fixed. The gearbox is configured to provide different gear ratios depending on operating conditions, allowing the system to adapt between engine-speed-optimized and propulsor-speed-optimized modes. This enables the propulsor to operate across its full optimum speed range while the engine operates efficiently, resolving the contradiction between fixed gearing limitations and adaptive operating requirements.
Solution Approach 2:
The patent changes the parameter of gear ratio from a fixed value to a variable parameter that can be adjusted based on operational needs. By enabling the gearbox to provide multiple gear ratios, the system can optimize the matching between engine speed and propulsor speed under different operating conditions, allowing both components to operate within their optimum ranges simultaneously.
2Productivity
If fixed gearing is used to connect engine to propulsor, then the mechanical transmission is simple, but the system cannot efficiently utilize both engine and propulsor throughout their optimum ranges
Solution Approach 1:
The patent implements dynamics in the gearing system by allowing the gear ratio to change based on operating conditions. This enables the system to optimize propulsion efficiency across different speed and load ranges, justifying the increased complexity through significant productivity improvements. The variable gearing allows the system to adapt to varying operational requirements, maximizing the utilization of both engine and propulsor.
3Speed
If the engine operates at high speed to drive the propulsor, then the propulsor achieves high speed, but the engine consumes excessive fuel outside its optimum range
Solution Approach 1:
The patent applies parameter changes by adjusting the gear ratio to decouple the direct relationship between engine speed and propulsor speed. This allows the engine to operate at its optimum speed range while the propulsor achieves the required speed through appropriate gear reduction or multiplication. The variable gear ratio enables independent optimization of engine operating parameters and propulsor speed, resolving the contradiction between high speed requirements and fuel efficiency.
Data Source
AI summary
An azimuthing drive system is provided for marine vessels. The azimuthing drive system includes a propulsion pod that houses a propulsor, which is configured to rotate about a first axis and to be driven by a first shaft generally orthogonal to the first axis. The propulsion pod is configured to swivel about the first shaft. The drive system also includes a gearbox connected to drive the first shaft, a diesel engine connected to drive the gearbox via a second shaft, and an electric motor connected to drive the first shaft via the gearbox or directly, whereby propulsion loads are shared between the diesel engine and the electric motor.