Flywheel Assembly Composite Ring Strain Matching
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Solution Overview
Problem
Existing flywheel assemblies face challenges in withstanding high rotational speeds due to material limitations, particularly in hybrid vehicles and uninterruptable power supplies, where high specific strength and low density materials are required to efficiently store kinetic energy without compromising durability under centrifugal forces.
Innovation Solution
A flywheel assembly design featuring an annular rotor and rotor support with a composite material ring that provides greater elasticity, allowing press-fitting and enhancing durability, along with a frusto-conical inner surface for strain matching and optimized load-bearing capabilities, and the use of magnetic particles for magnetic coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a metallic hub with composite fibre rim is used, then the flywheel can store kinetic energy, but the assembly cannot withstand the stresses at extremely high rotational speeds greater than 10,000 rev./min
Solution Approach 1:
The patent employs composite materials throughout the assembly - the rotor uses carbon fibres in a resin matrix, the ring uses glass or basalt fibres in a resin matrix, and the rotor support uses a composite material with fibres oriented to withstand centrifugal forces. These composite materials provide the necessary strength-to-weight ratio to withstand extremely high rotational speeds while storing kinetic energy.
Solution Approach 2:
The flywheel assembly is divided into distinct segmented components: the rotor, the ring, and the rotor support, each optimized for specific functions. The rotor stores kinetic energy, the ring provides strain matching and stress distribution, and the rotor support withstands centrifugal forces. This segmentation allows each component to be independently optimized for its specific role.
2Ease of manufacture
If the ring has greater elasticity than the rotor support, then the ring can be press fitted onto the rotor support, but the fitting process requires precise control to maintain structural integrity
Solution Approach 1:
The patent utilizes the elastic properties of the ring material as a key parameter, selecting materials with specific elastic moduli that allow press-fitting. The ring's greater elasticity compared to the rotor support enables it to deform during the press-fitting process and then recover, creating a secure interference fit without requiring excessive manufacturing precision.
3Reliability
If the frusto-conical inner surface angle is optimized for strain matching, then the rotor support and ring assembly maintains integrity under centrifugal forces, but the manufacturing of the conical surface requires high precision
Solution Approach 1:
The frusto-conical inner surface of the rotor support features locally optimized fibre orientation, with fibres arranged to match the strain distribution pattern under centrifugal loading. This local quality optimization ensures that the material properties align with the stress fields, maximizing assembly integrity while the precision conical geometry provides the necessary strain matching interface.
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 design significantly increases the assembly's durability and ability to withstand high centrifugal forces, ensuring efficient kinetic energy storage and maintaining structural integrity at extreme rotational speeds.
Implementation Method 1
The ring has a greater elasticity than the rotor support in the circumferential direction which allows it to be press fitted into the inner diameter of the rotor
Implementation Method 2
The angle defined by the frusto-conical inner surface with respect to a plane perpendicular to its longitudinal axis is selected so as to substantially strain match the rotor support with the ring. This ensures the integrity of the rotor support and ring assembly when subjected to centrifugal forces
Implementation Method 3
The amount of energy stored depends on the mass of the flywheel and its speed of rotation. The kinetic energy of the flywheel is proportional to the square of its angular velocity
Data Source
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AI summary
A flywheel for kinetic energy storage and its construction using composite materials. The amount of energy that may be stored in a given flywheel is dependent on the robustness of the flywheel assembly and how it responds to the stresses experienced at high rotational speeds. The present invention provides a flywheel assembly(70) having a longitudinal axis(81)and comprising an annular rotor(26)and a rotor support (74) for coupling the rotor to an axial shaft(76), wherein the rotor comprises fibres in a matrix material, and a ring (84) comprising fibres in a matrix material is mounted on the outer circumference of the rotor support and the rotor is mounted on the outer circumference of the ring, the rotor, rotor support and ring each having longitudinal axes which are coincident with the longitudinal axis of the assembly. The presence of the intermediate ring (84) formed of a composite material assists in the fabrication of the assembly and increases its durability by providing a suitable interface between the rotor and a rotor support.