Flywheel Rotor Support Composite Design

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Solution Overview

Problem

Existing flywheel assemblies face challenges in storing mechanical kinetic energy efficiently due to material limitations, particularly at high rotational speeds, as they need to be both strong and lightweight to withstand stresses and maintain structural integrity.

Innovation Solution

A rotor support is designed using a stack of unidirectional composite sheets with fibers oriented at different angles, including a side layer of woven fabric to prevent delamination, and a mid-layer of non-aligned fibers for cost reduction, ensuring quasi-isotropic properties and strain matching with the rotor for uniform deflection and stress distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If high rotational speeds are used to increase energy storage capacity, then kinetic energy storage increases, but structural integrity and resistance to delamination deteriorate

Engineering Contradiction:
Improvekinetic energy storageVSAvoidstructural integrity
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The rotor support uses a composite structure combining unidirectional carbon fibre sheets (for strength) with woven fabric layers (for delamination resistance). This composite material approach allows the flywheel to withstand the high centrifugal forces at 50,000-100,000 rev/min while maintaining structural integrity and preventing delamination between layers.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent adds a new dimensional element by incorporating woven fabric layers oriented at 45 degrees relative to the unidirectional sheets. This cross-ply arrangement creates a multi-dimensional reinforcement system that resists delamination forces acting parallel to the sheet planes, thereby improving reliability at high rotational speeds.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Strength

If unidirectional composite sheets are used to maximize strength, then material strength increases, but resistance to delamination deteriorates

Engineering Contradiction:
Improvematerial strengthVSAvoiddelamination
Core Design Contradiction:
StrengthVSObject-generated harmful factors

Solution Approach 1:

The patent combines unidirectional carbon fibre sheets (providing high tensile strength) with woven fabric reinforcement layers (providing delamination resistance). This composite material system addresses both requirements simultaneously by leveraging the complementary properties of different material configurations.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The woven fabric layers are strategically positioned at interfaces between unidirectional sheets and oriented at 45 degrees, creating local reinforcement zones specifically targeted at preventing delamination. This localized quality enhancement addresses the delamination issue without compromising the overall strength provided by the unidirectional sheets.

Inventive Principle:
Principle #3Local quality

3Stability of the object's composition

If multiple unidirectional sheets with different fiber orientations are stacked, then quasi-isotropic properties improve, but manufacturing complexity increases

Engineering Contradiction:
Improvequasi-isotropic propertiesVSAvoidmanufacturing complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent specifies a particular fiber orientation angle of 45 degrees for the woven fabric layers, which optimizes the quasi-isotropic properties of the composite structure. This parameter optimization ensures uniform strength and stiffness in all radial directions while maintaining manufacturing feasibility, avoiding the need for complex multi-angle stacking sequences.

Inventive Principle:
Principle #35Parameter changes

4Weight of moving object

If high specific strength materials are used to reduce density, then energy storage efficiency improves, but manufacturing cost increases

Engineering Contradiction:
ImprovedensityVSAvoidmanufacturing cost
Core Design Contradiction:
Weight of moving objectVSEase of manufacture

Solution Approach 1:

The patent uses carbon fibre composite materials which provide high specific strength (strength-to-density ratio), enabling lightweight construction for efficient energy storage. The composite structure allows optimization of material placement to achieve required performance with minimal mass, thereby improving energy storage efficiency while managing manufacturing costs through targeted material usage.

Inventive Principle:
Principle #40Composite materials

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

The solution provides a stiff and reliable flywheel assembly capable of operating at high speeds with enhanced structural integrity, resisting delamination and maintaining uniform properties, thus effectively storing kinetic energy while reducing material costs.

Implementation Method 1

the body comprises a stack of sheets of a composite material including fibres, the stack includes at least two unidirectional sheets, each having substantially all of their fibres extending in the same direction

Methodology Applied
Scientific EffectComposite materials: Composite Materials

Implementation Method 2

all of the sheets in the stack are unidirectional sheets of carbon fibre

Methodology Applied
Scientific EffectFiber reinforcement:

Implementation Method 3

the or each side layer extends at least partway over an outer circumferential edge surface of the stack of sheets to resist delamination of the stack

Methodology Applied
Scientific EffectDelamination resistance:

Implementation Method 4

it is sufficiently stiff to ensure that its resonant frequencies of vibration are greater than the rotational frequencies encountered during its operation

Methodology Applied
Scientific EffectResonant frequency: Resonance

Implementation Method 5

the frusto-conical inwardly facing surface of the support defining an angle with respect to the longitudinal axis of the body which is selected such that the support is strain matched with the rotor

Methodology Applied
Scientific EffectStrain matching:

Implementation Method 6

The kinetic energy of the flywheel is proportional to the square of its angular velocity

Methodology Applied
Scientific EffectKinetic energy storage: Flywheel

Implementation Method 7

The amount of energy stored depends on the mass of the flywheel and its speed of rotation

Methodology Applied
Scientific EffectMoment of inertia: Moment of Inertia

Data Source

PatentEP3022462B8Flywheels for energy storage and methods of manufacture thereof
Publication Date: 2019.09.11 GKN HYBRID POWER

AI summary

A flywheel used for kinetic energy storage and the construction of the flywheel using composite materials. The present invention provides a rotor support (74) for coupling an annular flywheel rotor (26) to a shaft (76) for rotation with the shaft, the support comprising a body having a longitudinal axis (81) about which it rotates in the finished flywheel assembly, wherein the body comprises a stack of sheets (101 to 5) of a composite material including fibres, the stack includes at least two 10 unidirectional sheets, each having substantially all of their fibres extending in the same direction, and the fibres of one of the unidirectional sheets are orientated at a different angleto the longitudinal axis of the body to the fibres in another unidirectional sheet. The body includes at least one side layer (40, 42) of woven fabric provided over a side of the stack of sheets. The rotor support configuration of the invention providesa stiff construction.