Dual Marine Propulsion Shaft Synchronization in Trolling Mode

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Solution Overview

Problem

Existing marine propulsion control systems fail to synchronize engine speed control during trolling operations, limiting their effectiveness in scenarios requiring synchronized thrust from multiple propulsion systems.

Innovation Solution

A marine propulsion control system that synchronizes the shaft speeds of dual propulsion systems using a control module to adjust clutch slip based on operator inputs, ensuring synchronized thrust during trolling operations by controlling shaft speed rather than engine speed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If engine speed is controlled to synchronize propulsion systems, then synchronized thrust is achieved, but trolling mode with constant engine speed cannot be maintained

Engineering Contradiction:
Improvesynchronized thrustVSAvoidtrolling mode capability
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system dynamically switches between two control modes: in sync mode, engine speed is actively controlled to synchronize propulsion systems; in troll mode, engine speed is held constant while clutch slip is controlled. The control system adapts its behavior based on the selected mode, allowing both synchronized operation and constant speed trolling to function effectively.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the controlled parameter based on operating mode: during sync mode, engine speed is the controlled parameter for synchronization; during troll mode, clutch slip becomes the controlled parameter while engine speed remains constant. This parameter switching resolves the contradiction by allowing each mode to optimize its specific performance requirement.

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If clutch slip is controlled to maintain constant engine speed during trolling, then fine speed control is achieved, but synchronized control of multiple propulsion systems becomes impossible

Engineering Contradiction:
Improvefine speed controlVSAvoidsynchronized control
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The control system dynamically adjusts which parameter is actively controlled based on the selected mode. In troll mode, clutch slip is controlled to maintain constant engine speed, providing fine speed control. In sync mode, the system switches to controlling engine speed to synchronize propulsion systems. This dynamic adaptation allows both fine speed control and synchronized control to function in their respective operating contexts.

Inventive Principle:
Principle #15Dynamics

3Ease of operation

If a single lever controls both propulsion systems in synchronized mode, then operational simplicity is improved, but the ability to operate in troll mode with constant engine speed is lost

Engineering Contradiction:
Improvesingle lever controlVSAvoidtroll mode operation
Core Design Contradiction:
Ease of operationVSAdaptability or versatility

Solution Approach 1:

The single lever control system is designed to perform multiple functions depending on the selected mode. In sync mode, the lever controls engine speed to synchronize both propulsion systems. In troll mode, the lever controls clutch slip while engine speed remains constant. The control system's multi-functionality allows one lever to provide both synchronized control and constant speed trolling capabilities.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP4373740B1Marine propulsion control system with syncronized troll and method of operation
Publication Date: 2026.04.01 CATERPILLAR INC
  • EP4373740B1 patent drawingFigure 1~2
  • EP4373740B1 patent drawingFigure 3
  • EP4373740B1 patent drawingFigure 4

AI summary

A marine vessel (100) includes a hull (110), an operator station (130) having an operator interface (200) configured to receive a mode input and a lever position input, a left propulsion system (150), a right propulsion system (155), and a control module (410). Each of the propulsion systems (150, 155) includes an engine (320), a transmission (330), a troll valve (360) configured to adjust clutch slip, a shaft (340), a shaft speed sensor (370) configured to detect the speed of rotation of the shaft (340), and a propeller (350). The control module (410) is configured to receive the mode input and the lever position input from the operator interface (200), receive signals from the left shaft sensor (370) indicating a left shaft speed, receive signals from the right shaft (375) sensor indicating a right shaft speed, determine if the vessel (100) is operating in a trolling state, and determine if a sync mode is active, based on the mode input. If the sync mode is active and the vessel (100) is in a trolling state, the speed of the left shaft (340) and the right shaft (345) are synchronized.