Blade Reversal Device Using Linear Rack Actuation

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Solution Overview

Problem

The existing mechanisms for reversing blades in tidal power plant runner units face inefficiencies due to limited angle of rotation and increased friction, leading to reduced efficiency when operating in reverse mode, and are heavier and prone to wear due to complex gear systems.

Innovation Solution

A device comprising an annular lever fixed to the blade, a main servomotor with a piston for initial rotation, and an auxiliary servomotor with a linear rack to facilitate further rotation beyond the dead zone, reducing friction and weight by eliminating the need for a rotative gear system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a rotative gear system (toothed sector and crank) is used to enable complete blade inversion, then the blade can rotate beyond 180 degrees, but the mechanism becomes heavier and more prone to wear due to multiple moving elements

Engineering Contradiction:

Improveblade rotation angleVSAvoidmechanism weight

Core Design Contradiction:

Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The patent extracts the rotative gear elements (toothed sector and crank) from the mechanism and replaces them with a linear rack system. The linear rack translates linearly instead of rotating, eliminating the need for a crank and reducing the number of moving parts that contribute to weight and wear.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent substitutes a mechanical rotative gear system with a linear rack and pinion system. This replacement maintains the ability to achieve complete blade inversion while reducing complexity and weight by eliminating the crank and reducing the number of articulated connections.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If a rotative gear system with multiple articulated elements is used, then complete blade inversion is achieved, but friction increases and wear occurs at the coupling rod-crank interface

Engineering Contradiction:

Improveblade rotation angleVSAvoidmechanism wear

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent removes the crank and its associated articulated connections from the mechanism. By using a linear rack that translates in a straight line, the system eliminates the coupling rod-crank interface that was prone to wear and high friction.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The linear rack acts as an intermediary element that translates the reciprocating motion of the piston into blade rotation without requiring articulated connections. The rack engages with a gear or cam to produce the rotational motion, reducing direct friction between moving parts.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If the hub supports multiple pivots (pin for crank, pin for servomotor) in a rotative gear system, then complete inversion is enabled, but the hub design becomes more complex and heavier

Engineering Contradiction:

Improveblade inversion capabilityVSAvoidhub weight

Core Design Contradiction:

Adaptability or versatilityVSWeight of stationary object

Solution Approach 1:

The patent extracts the crank and its pivot pin from the hub assembly. The linear rack system requires fewer pivot points, simplifying the hub design and reducing its weight while maintaining the capability for complete blade inversion.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The linear rack serves multiple functions: it translates piston motion, engages with the gear/cam mechanism, and enables complete blade inversion. This multi-functionality reduces the need for separate components and pivots in the hub design.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

Enables efficient blade inversion beyond 180 degrees with reduced wear and weight, maintaining high efficiency in both direct and reverse water flow modes, and simplifies the mechanical design by using a linear rack instead of a rotative gear.

Implementation Method 1

a main servomotor comprising a piston adapted to reciprocate along a shaft of the runner unit and coupled to the annular lever such to cause a first rotation of the blade

Methodology Applied

Scientific EffectMechanical coupling: Mechanical Advantage

Implementation Method 2

the auxiliary servomotor comprises a reciprocating linear rack configured to cooperate with a toothed sector provided on the annular lever

Methodology Applied

Scientific EffectRack and pinion mechanism: Rack and Pinion

Data Source

PatentEP3101270B1Device for reversing a blade of a runner unit

Publication Date: 2019.07.31 GE RENEWABLE TECH

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AI summary

The present invention generally relates to a runner unit (3) of a tidal power plant, and more particular to a device (1) for reversing a blade (2) of the runner unit. The device according to the invention is lighter and more efficient with respect to known solutions which involve articulated mechanisms as it is based on an auxiliary servomotor (6) including a reciprocating linear rack (61) which acts on the blade (2) to be reversed.