Conical Fluid Dynamic Bearing Sealing Gap Design
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Solution Overview
Problem
Existing fluid dynamic bearing systems with conical bearings face challenges in filling and inspecting the bearing fluid level due to the design of the covering cap, which prevents visual inspection and requires assumptions for fluid quantity, leading to potential underfilling or overfilling, especially with geometric dimensional deviations.
Innovation Solution
The sealing gap is bounded by the bearing cone and rotor component surfaces instead of a covering cap, allowing for easy filling and visual inspection of the fluid level before cap installation, and the cap only serves a protective function, simplifying the design and eliminating the need for a leak-proof connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a covering cap is used to seal the bearing, then the bearing structure is closed and protected, but the filling level cannot be optically inspected and the design becomes more complex
Solution Approach 1:
The sealing function is segmented into two parts: the covering cap provides structural protection and contamination barrier, while the sealing gap between the bearing cone and rotor component provides both sealing and optical inspection capability. This segmentation allows each component to fulfill its specific function without compromising the other.
Solution Approach 2:
The sealing gap acts as an intermediary element between the bearing interior and exterior, serving dual purposes: it maintains the sealing function while allowing optical inspection of the filling level. This intermediary space resolves the contradiction by providing a transmission path for light while maintaining fluid retention.
2Ease of operation
If a covering cap with filling aperture is used, then the bearing can be filled, but the connection must be leak-proof increasing manufacturing complexity
Solution Approach 1:
The filling operation is extracted from the sealed bearing structure. The bearing is filled through the open sealing gap before the covering cap is installed, eliminating the need for complex leak-proof filling connections. The covering cap is then installed as a simple protective cover without requiring precise sealing during the filling process.
Solution Approach 2:
The filling action is performed preliminarily, before the covering cap is installed. This preliminary filling through the accessible sealing gap simplifies the overall process by separating the filling operation from the sealing requirement, allowing use of simpler connection methods for the covering cap.
3Manufacturing precision
If geometric dimensional deviations occur, then incorrect filling levels result, but the covering cap prevents detection and correction
Solution Approach 1:
The open sealing gap provides continuous visual feedback on the filling level, allowing operators to detect and correct filling inaccuracies caused by dimensional deviations. This feedback mechanism enables real-time verification and adjustment, ensuring correct filling levels despite manufacturing variations.
Solution Approach 2:
The bearing fluid's visual properties (color, meniscus visibility) provide indication of the filling level. Through the open sealing gap, the fluid's optical characteristics can be observed to determine whether the correct filling level has been achieved, compensating for dimensional variations.
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
This design facilitates easier filling and level control, reduces manufacturing complexity and costs, and eliminates the need for stringent sealing, while ensuring effective fluid retention through capillary and centrifugal effects, preventing leakage.
Implementation Method 1
The bearing fluid is filled into the sealing gap through an opening in the covering cap and reaches the bearing gap through the use of capillary forces
Implementation Method 2
ensuring effective fluid retention through capillary and centrifugal effects
Data Source
AI summary
A fluid dynamic bearing system having a first conical bearing and a second conical bearing working in opposition to the first conical bearing, wherein the two conical bearings are disposed along a stationary shaft, wherein the first and the second conical bearing each comprises a bearing cone disposed on the shaft having bearing surfaces as well as a conical counter bearing disposed in a rotor component that are separated from one another by a bearing gap filled with a bearing fluid, wherein the bearing gap has a first open end that is sealed by a first sealing gap partially filled with bearing fluid, wherein the bearing fluid in the sealing gap forms a fluid meniscus. The sealing gap is bounded by sealing surfaces of the bearing cone and associated sealing surfaces of the rotor component, wherein the smallest radius R1 of the sealing surfaces of the rotor component is larger than the largest outer radius R2 of the bearing cone and larger than the greatest possible distance R3 of the fluid meniscus from the rotational axis.