Wind Turbine Shaft Seal With Bearing for Misalignment
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Solution Overview
Problem
Conventional sealing methods for rotating shafts in wind turbine powertrains, such as annular lip seals and labyrinth seals, are ineffective due to alignment errors between shafts, leading to increased wear and leakage, particularly in applications where the pitch tube passes through different environments.
Innovation Solution
A seal arrangement comprising a seal member and a bearing, where the seal member is locked to the rotating shaft, accommodating alignment errors through a flexible annular seal that closes an annular gap between the shafts, providing a low-friction interface and effective sealing even with high speed differentials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sealing methods (annular lip seals or labyrinth seals) are used, then sealing is provided, but alignment errors between shafts cause increased wear and reduced sealing effectiveness
Solution Approach 1:
A bearing is introduced as an intermediary component between the seal member and the rotating shaft. The bearing supports the seal member and allows it to accommodate misalignment through radial movement, while the seal member itself remains positioned to effectively seal against the shaft. This intermediary bearing absorbs the alignment errors that would otherwise cause wear and sealing failure.
Solution Approach 2:
The seal member is made dynamically adjustable through the bearing support, allowing it to move radially to accommodate misalignment between shafts. This dynamic positioning capability enables the seal to maintain effective sealing contact despite manufacturing tolerances and operational deflections, transforming a static sealing arrangement into an adaptive one.
2Reliability
If the seal member is locked to the rotating shaft, then sealing is maintained, but alignment errors cause lateral movement and wear
Solution Approach 1:
The bearing serves as a mediator between the locked seal member and the rotating shaft. It allows the seal member to be locked to the shaft while accommodating lateral movements and misalignments through the bearing's radial clearance, preventing direct contact and wear between the seal and shaft surfaces.
Solution Approach 2:
The bearing provides a cushioning effect beforehand, absorbing misalignment and lateral movement before they can cause wear or leakage. This preemptive cushioning protects the sealing interface from harmful forces that would otherwise occur during operation.
3Ease of operation
If remote bearings are used to support the shaft, then shaft rotation is enabled, but significant lateral movement occurs at the sealing point
Solution Approach 1:
A local bearing is positioned close to the sealing point to support the seal member, acting as an intermediary that prevents lateral movement at the critical sealing interface. This local support compensates for the lateral movement that would otherwise occur due to remote bearing support, maintaining sealing alignment without interfering with shaft rotation.
Solution Approach 2:
The bearing support is applied locally at the sealing point rather than relying on remote support. This localized quality control ensures that the sealing interface maintains its alignment and precision where it is most needed, while allowing the shaft to rotate freely through the remote bearings.
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 seals against alignment errors, reducing wear and leakage, and is compact, ensuring reliable operation in wind turbine powertrains by accommodating eccentricities and maintaining efficient rotation without excessive space usage.
Implementation Method 1
The bearing supports the seal member on the pitch tube such that the seal member is able to rotate relative to the pitch tube about a rotational axis. The bearing provides a low-friction interface between the seal member and the pitch tube.
Implementation Method 2
A flexible annular seal extends between a surface of the first shaft and a surface of the seal arrangement to close the annular gap. The flexible nature of the seal allows it to deform and accommodate alignment errors between the shafts while maintaining sealing effectiveness.
Data Source
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AI summary
Apparatus comprising a first shaft and a second shaft supported in a substantially concentric relationship so that they are able to rotate relative to one another about a rotational axis (R); wherein one of the first and second shafts passes through a bore defined in the other of the first and second shafts; a seal arrangement between the first and second shafts, said seal arrangement being locked from rotational movement relative to said first shaft; wherein the seal arrangement comprises a first portion that is rotatably mounted on the second shaft by a bearing and a second portion that is configured to seal against a running surface defined by the second shaft. Advantageously, since the seal arrangement is rotatably mounted on the same shaft against which it forms a seal, the sealing arrangement accommodates for alignment errors between the first and second shafts.