Stator Support Element for Vibration Control and Thermal Expansion
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Solution Overview
Problem
Existing stator assemblies in electrical machines face challenges with high vibration levels in round connection arms due to resonance issues, which can lead to cracks and breakage, and existing stiff support solutions hinder thermal expansion, causing further stress and potential loosening of connections.
Innovation Solution
A support element made of glass fibre reinforced insulation material with a lamination direction along the contour, featuring a resilient design with screw-type connections and gluing or fixation with cords/tapes, allowing axial, radial, and tangential displacement for thermal expansion while detuning vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a very stiff support is applied between the round connection arm and the support ring with cords or tape together with resin, then the Eigen-frequency is detuned out of the range of 100 to 140 Hz and vibration amplitude is reduced, but thermal expansion is hindered which increases stress at the strands close to the lug and considerably increases the danger of cracks
Solution Approach 1:
The support element changes its mechanical parameters dynamically: it provides high stiffness in the radial direction to detune Eigen-frequency and reduce vibrations, while maintaining flexibility in the axial direction to allow thermal expansion. This is achieved through its specific geometric design and material properties that create direction-dependent mechanical behavior.
Solution Approach 2:
The support element is made of glass fibre reinforced insulation material, which combines the high strength and stiffness of glass fibres with the flexibility and thermal resistance of insulation material. This composite structure enables simultaneous vibration reduction and thermal expansion accommodation.
2Reliability
If a stiff support is applied to reduce vibrations, then vibration amplitude is reduced, but the high stress to the cords/tapes of the stiff support may lead to a loosening of the connection over time
Solution Approach 1:
The support element modifies the stress distribution by providing flexible support that accommodates thermal movements, thereby reducing cyclic stress fluctuations on the cords/tapes. This decreases the rate of connection loosening and extends service life.
3Strength
If the round connection ends are not fixed to the supporting structure over a long distance, then the structure remains flexible for thermal expansion, but the round connection arms have a high risk of vibrations
Solution Approach 1:
The support element acts as an intermediary component between the round connection arm and the support ring. It provides the necessary mechanical coupling to reduce vibrations while simultaneously allowing thermal expansion through its flexible design, thus mediating between the two conflicting requirements.
4Reliability
If a very stiff support is applied between the round connection arm and the support ring, then the Eigen-frequency is detuned, but thermal expansion is blocked which increases the stress at the strands close to the lug
Solution Approach 1:
The support element exhibits direction-dependent mechanical parameters: high radial stiffness for vibration control and high axial flexibility for stress-free thermal expansion. This anisotropic behavior eliminates stress concentration at critical locations while maintaining vibration reduction.
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 effectively reduces vibration amplitudes and stresses, allowing thermal expansion without causing breakage, making it easy to install and cost-efficient.
Implementation Method 1
thermal expansion, which does occur during operation of the machine, should not be blocked. Such thermal expansion mainly occurs along the axial direction (usually causing a displacement of the connection arm of about 2-3 mm)
Implementation Method 2
The Eigen frequency of these arms often need to be detuned (e.g. no resonance between 100 and 140 Hz for 60 Hz applications) or at least the vibration levels have to be reduced to a minimum
Implementation Method 3
Some round connections arms have Eigen frequencies close to 120 Hz (for 60 Hz applications) or 100 Hz (for 50 Hz applications)
Data Source
AI summary
The present disclosure relates to a stator assembly for an electrical machine, and more in particular relates to a support element utilized within the stator assembly in order to improve its performance. The support element allows the thermal expansion of round connection arms while detuning the Eigen-frequency and reducing the amplitude of the vibrations.