PTO Unit Connection Mechanism for Wave Energy Recovery

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Solution Overview

Problem

Existing wave energy recovery systems face challenges in efficient maintenance and repair, as the power-take-off (PTO) unit must be stopped and locked before removal, which is time-consuming and expensive, and modular energy transfer mechanisms are prone to fatigue due to high forces and torques, making installation and removal difficult, especially in dynamic ocean conditions.

Innovation Solution

The PTO unit is designed as a separate modular structure that can be easily locked motionless and removed without stopping the panel's reciprocating motion, allowing for remote-controlled connection and disconnection using alignment rails and actuator means, enabling easy installation, maintenance, and replacement without disturbing the panel's operation, and allowing for different PTO units to be used with similar connection means.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the PTO unit is permanently connected to the reciprocating panel, then the structure is simple and robust, but the maintenance and repair operations become time-consuming and expensive because the panel must be stopped and locked before removal

Engineering Contradiction:
Improvestructural robustnessVSAvoidmaintenance time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The PTO unit is divided into a separate modular component that can be independently connected to and disconnected from the reciprocating panel. This segmentation allows the PTO unit to be removed for maintenance without stopping the panel, resolving the contradiction between structural robustness and maintenance time by enabling quick detachment while maintaining operational integrity during connection.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The connection between the PTO unit and the reciprocating panel is made dynamic rather than static. The PTO unit can be connected when the panel is moving and disconnected without stopping the panel, transforming the fixed connection into a flexible, adaptable connection that resolves the time loss during maintenance while maintaining reliable power transfer during operation.

Inventive Principle:
Principle #15Dynamics

2Ease of manufacture

If modular energy transfer mechanisms are connected directly onto the pivot shaft, then installation and removal can be done in flat configuration, but the structure becomes extremely prone to fatigue breakdowns due to massive forces and torques

Engineering Contradiction:
Improveinstallation easeVSAvoidfatigue resistance
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

An intermediary connection mechanism is introduced between the PTO unit and the pivot shaft. This intermediary allows the PTO unit to be connected to the moving panel rather than directly to the stationary pivot shaft, reducing the transmission of massive forces and torques to the modular components while still enabling easy installation and removal during flat configuration.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

Instead of connecting the modular PTO unit directly to the rigid pivot shaft, the connection is inverted to attach it to the moving panel. This reversal of the connection point allows the panel's motion to accommodate the modular connection while reducing stress concentrations that would otherwise occur at the pivot shaft interface.

Inventive Principle:
Principle #13The other way round (Inversion)

3Ease of operation

If the panel is stopped and locked for mounting or removing the driving rod and hydraulic cylinder, then the connection can be made securely, but the operation becomes time-consuming and expensive

Engineering Contradiction:
Improveconnection securityVSAvoidmounting time
Core Design Contradiction:
Ease of operationVSLoss of time

Solution Approach 1:

The PTO unit is designed with preliminary alignment features and connection mechanisms that allow it to be attached to the moving panel without requiring the panel to be stopped. The connection is prepared in advance with proper alignment, enabling secure attachment during motion and eliminating the time-consuming stopping and locking operations.

Inventive Principle:
Principle #10Preliminary action

4Ease of operation

If the panel is lowered into flat survival mode configuration for installation or removal of modular energy transfer mechanisms, then the task becomes easy and fast, but it becomes extremely difficult or almost impossible in prevailing ocean conditions where waves never stop moving

Engineering Contradiction:
Improveinstallation easeVSAvoidoperational flexibility
Core Design Contradiction:
Ease of operationVSAdaptability or versatility

Solution Approach 1:

The connection system is designed to be dynamic, allowing the PTO unit to be connected to and disconnected from the panel during its normal reciprocating motion caused by waves. This eliminates the need to lower the panel to a flat survival mode configuration, enabling installation and removal operations to proceed in prevailing ocean conditions without stopping the wave-driven motion.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3337971B1Arrangement in a wave energy recovery apparatus
Publication Date: 2020.04.15 AW ENERGY
  • EP3337971B1 patent drawingFigure 1
  • EP3337971B1 patent drawingFigure 2~3
  • EP3337971B1 patent drawingFigure 4

AI summary

(57) Abstract This invention relates to an arrangement in a wave energy recovery apparatus comprising at least a base (1), a reciprocating panel (2), a pivot shaft (4) for the reciprocating panel (2), a control system, a power-take- off (PTO) unit (5) with a primary shaft (5a) to convert kinetic energy of waves or tidal currents to another type of energy, and a connection mechanism (2a) to connect the PTO unit (5) to the panel (2) or to the pivot shaft (4) and to disconnect the PTO unit (5) from the panel (2) or from the pivot shaft (4). The arrangement comprises actuator means (5b) to connect the primary shaft (5a) of the PTO unit (5) either to the back and forth moving panel (2) or its pivot shaft (4) while the panel (2) and the pivot shaft (4) are reciprocating.