Adaptive Labyrinth Shaft Seal for High-Speed Electric Machines
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Solution Overview
Problem
Conventional sealing solutions for electric machine output shafts, such as labyrinth seals and friction seals, fail to provide sufficient tightness and have limited lifespan, especially in extreme conditions, and are not suitable for high-speed applications due to heating issues and imperfect fluid sealing at standstill.
Innovation Solution
A sealing arrangement featuring a structurally continuous labyrinth seal with zig-zag sections and a second seal made of elastic material, which converts to a clearance seal at high speeds to reduce friction and heat, combined with a dust and particle seal and a lubricant transfer system to manage centrifugal forces and prevent contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional radial seals are used, then sealing tightness is improved, but friction increases causing heating which limits use at high speeds
Solution Approach 1:
The seal system dynamically adapts its configuration based on operating conditions. The second seal element can assume different positions relative to the shaft surface - contacting at low speeds for tight sealing, and retracting at high speeds to reduce friction and heat generation.
Solution Approach 2:
The system changes the physical state and configuration of the sealing elements according to operational parameters. The second seal element transitions between contact and clearance states based on rotational speed, optimizing performance across different operating regimes.
2Device complexity
If conventional labyrinth seals are used, then structure simplicity is maintained, but sealing effectiveness is insufficient against fluids at standstill
Solution Approach 1:
The invention merges two sealing mechanisms - a labyrinth seal for structural simplicity and a second seal element for enhanced fluid sealing - into a unified system that leverages the strengths of both approaches.
Solution Approach 2:
The sealing system uses composite construction with a labyrinth structure and an additional elastic seal element, combining different sealing principles to achieve superior overall performance.
3Reliability
If the second seal maintains constant contact with the shaft surface, then sealing tightness is improved, but friction and heat generation increase at high speeds
Solution Approach 1:
The second seal element's position is dynamically adjusted based on rotational speed. At high speeds, centrifugal force causes the element to retract from the shaft surface, reducing friction and thermal loading to extend seal lifespan.
Solution Approach 2:
Centrifugal force acts as a counterbalancing mechanism that opposes the sealing contact force at high speeds, automatically reducing the normal force between the seal element and shaft surface to minimize wear and heat generation.
4Reliability
If multiple seal elements are added to improve sealing, then sealing efficiency is improved, but device complexity increases
Solution Approach 1:
The second seal element serves multiple functions - providing fluid sealing at standstill and low speeds, and acting as a clearance seal at high speeds - thereby improving sealing efficiency without proportionally increasing structural complexity.
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 enhanced sealing efficiency and longevity by minimizing friction and heat, effectively preventing fluid and particle ingress at various speeds while allowing for lubricant management, thus improving the reliability of electric machines in extreme conditions.
Implementation Method 1
the second seal (112) comprising an elastic material part (114) which is pressed, by the spring part (116) in the radial direction, the elastic material part (114) against a surface (118) of the second part (102) at rotational speeds a centrifugal force of which to the second seal (112) is weaker than a spring force of the spring part (116)
Implementation Method 2
opening a gap (120) between the elastic material part (114) and said surface (118) at rotational speeds the centrifugal force of which to the second seal (112) is greater than the spring force of the spring part (116)
Implementation Method 3
A plurality of zig-zag sections (110) of a structurally continuous labyrinth seal (108) in a radial direction of the electric machine (10) between the first and second parts (102, 104)
Data Source
AI summary
A sealing arrangement for an electric machine, which is between a first part attached to a rotatable shaft and a second part immobile with respect to a stator of the electric machine includes a plurality of zig-zag sections of a channel of a labyrinth seal in a radial direction of the electric machine. The channel of the labyrinth seal includes a second seal which is fixedly attached to the first part and which has an elastic material part, the second seal is pressed in the radial direction against a surface of the second part, a normal of which has a component parallel to the radial direction, at rotational speeds a centrifugal force of which to the second seal is weaker than a spring force of the second seal, and the second seal opening a gap between the second seal and said surface at rotational speeds the centrifugal force of which to the second seal is greater than the spring force of the second seal.