Vessel Propulsion Asymmetric Thrust Lateral Control
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Solution Overview
Problem
Conventional vessel propulsion systems face limitations in lateral movability due to the difference in maximum forward and backward thrusts, where the maximum backward thrust is often smaller than the maximum forward thrust, restricting the resultant force during lateral movement.
Innovation Solution
A vessel propulsion system with two propulsion devices on either side of the hull, controlled to generate backward thrust on the commanded side and forward thrust on the opposite side, with adjustable steering angles to position the resultant force's operating point off the central line, allowing greater utilization of forward thrust for lateral movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the propulsion device is configured with limited steering angle (less than 360 degrees), then the device complexity is reduced, but the maximum backward thrust becomes smaller than the maximum forward thrust
Solution Approach 1:
The patent applies inversion by reversing the traditional symmetric thrust configuration. Instead of using equal forward and backward thrusts from both propulsion devices, the system uses one propulsion device to generate forward thrust while the other generates backward thrust. This asymmetric configuration allows the limited-steering-angle propulsion devices to achieve effective lateral movement without requiring 360-degree rotation capability.
Solution Approach 2:
The patent implements asymmetry in the thrust configuration where the left and right propulsion devices operate differently during lateral movement. One device operates in forward thrust mode while the other operates in backward thrust mode, creating an asymmetric force distribution that overcomes the limitation of unequal maximum thrusts and enables effective lateral propulsion.
2Device complexity
If the propulsion device uses propeller rotation for backward thrust, then the device structure is simplified, but the backward thrust efficiency decreases
Solution Approach 1:
The patent applies inversion by using the propeller's forward rotation capability to generate backward thrust through strategic positioning and directional control. Instead of requiring separate mechanisms for forward and backward propulsion, the system reverses the conventional approach by using one propeller's forward thrust and another propeller's backward rotation to achieve lateral movement, thereby maintaining structural simplicity while improving backward thrust efficiency.
3Ease of operation
If the thrust magnitudes are equalized for lateral movement, then the lateral movability is improved, but the forwardly driven propulsion device cannot utilize its reserve force
Solution Approach 1:
The patent applies partial action by having the forwardly driven propulsion device operate at less than its maximum capacity. The system deliberately uses only the necessary portion of the forward thrust to balance the backward thrust, allowing the forward propulsion device to maintain reserve force while achieving effective lateral movement. This prevents over-utilization and preserves productivity potential.
4Device complexity
If the resultant force operating point is positioned on the hull center line, then the lateral movement control is simplified, but the maximum lateral force is limited by the smaller backward thrust
Solution Approach 1:
The patent implements asymmetry in the thrust configuration where the left and right propulsion devices operate differently during lateral movement. One device operates in forward thrust mode while the other operates in backward thrust mode, creating an asymmetric force distribution that overcomes the limitation of unequal maximum thrusts and enables effective lateral propulsion.
Data Source
AI summary
A vessel propulsion system includes two propulsion devices that are disposed on a left side and on a right side, respectively, with respect to a central line extending in a front-rear direction through a rotational center of a hull, an operating device that outputs a lateral movement command including a commanded direction, and a controller. The controller is configured and programmed to control the thrust and the steering angle of each of the two propulsion devices so that, when the operating device outputs a lateral movement command, a first propulsion device on a side existing in the commanded direction generates a backward thrust, whereas a second propulsion device generates a forward thrust, and so that an operating point of a resultant force of the thrusts of the two propulsion devices is positioned to deviate to the side in the commanded direction from the central line, and so that a direction of action of the resultant force follows the commanded direction.