Trawl Door Shutter Rotation for Energy Reduction

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Solution Overview

Problem

Existing trawl door control systems face inefficiencies due to high energy consumption from pivoting flaps and sliding surfaces, which are mechanically vulnerable and prone to wear, and have difficulty protecting control components from impacts.

Innovation Solution

A trawl door design featuring hydrofoils with overlapping sequences and shutters that rotate around a pivoting axis, orienting to move parallel to their surfaces, minimizing energy use and protecting components by positioning them inside the door.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If pivotable flaps are used for trawl door control, then positional control capability is improved, but energy consumption increases substantially due to water pressure forces acting parallel to flap motion

Engineering Contradiction:

Improvepositional control capabilityVSAvoidenergy consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

Instead of moving the flap surface parallel to water pressure forces (conventional approach), the invention inverts the motion direction so that the flap surface moves perpendicular to water pressure forces. The flap rotates about an axis parallel to the water flow direction, causing the flap surface to sweep through an arc that is perpendicular to the pressure forces, thereby minimizing energy consumption.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The invention changes the motion parameter of the control surface from linear/sliding motion to rotational motion about a specific axis. By rotating the flap about an axis parallel to the water flow rather than pivoting it perpendicular to the flow, the relative orientation between motion direction and water pressure forces is changed, reducing the work required against pressure forces.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If sliding surfaces are used for trawl door control, then positional control capability is improved, but mechanical wear and friction increase

Engineering Contradiction:

Improvepositional control capabilityVSAvoidmechanical wear resistance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The invention replaces the sliding mechanical contact system with a rotational pivot system. Instead of surfaces sliding against each other (which generates friction and wear), the flap rotates about a pivot axis where contact occurs at a line or point rather than across a surface, significantly reducing friction and wear.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If flaps and foil extensions are positioned on the trawl door for control, then positional control capability is improved, but mechanical vulnerability to impacts increases

Engineering Contradiction:

Improvepositional control capabilityVSAvoidmechanical vulnerability

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The invention nests the control flaps within the structure of the trawl door itself. The flaps are positioned on the inner surface of the door and rotate within the door's structural boundaries, so that the door structure protects the flaps from external impacts. The flaps are essentially nested within the protective envelope of the door structure.

Inventive Principle:

Principle #7Nested doll (Nesting)

4Adaptability or versatility

If pivotable flaps are used for trawl door control, then positional control capability is improved, but mechanical complexity increases

Engineering Contradiction:

Improvepositional control capabilityVSAvoidmechanical complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The invention segments the control function into multiple independent flap units that can be controlled individually. Each flap is a separate, simple rotational element rather than a complex integrated mechanism. This segmentation allows for simpler individual components while achieving comprehensive control capability through coordinated operation of multiple segments.

Inventive Principle:

Principle #1Segmentation

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

This design significantly reduces mechanical work required for positional control, enhances energy efficiency, and provides robust protection against impacts, maintaining performance and reducing operational costs.

Implementation Method 1

Water is a heavy medium and at typical towing velocities of 3-6 knots substantial pressure forces will impact a pivotable flap

Methodology Applied

Scientific EffectHydrodynamic pressure forces: Drag

Implementation Method 2

The trawl doors are hydrodynamic wings which upon being towed by the towing vessel (trawler) will generate outwards directed forces

Methodology Applied

Scientific EffectHydrodynamic lift: Aerofoil

Data Source

PatentEP4064835B1A trawl door

Publication Date: 2024.10.30 VOLU VENTIS APS

Figure 1~2A
Figure 2B~2C
Figure 3A~3B

AI summary

The disclosure relates to a trawl door (2) comprising a plurality of hydrofoils (9), one or more shutters (20) extending in the longitudinal direction of the plurality of hydrofoils, and drive means (21) for rotating the shutters about a pivoting axis, wherein the drive means are arranged to rotate the shutters between a disengaged position and an engaged position. The disclosure further relates to the use of a set of trawl doors and a round-shaped elongated element for a trawl door.