Conical Fluid Dynamic Bearing Air Bubble Discharge
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Solution Overview
Problem
Fluid dynamic bearings face challenges in suppressing the harmful effects of air bubbles, which can impair their functionality due to inadequate design in existing spindle motors, leading to reduced lifespan and strength.
Innovation Solution
A conical bearing member with a specific configuration, including a conical surface, a tapered seal, and a circulation hole, is used to support the rotor, where the circulation hole communicates with the tapered seal and is spaced apart from the first gap to prevent air bubbles from being drawn back into the gap, ensuring effective lubrication and bubble release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional fluid dynamic bearing is used, then the bearing can support the rotor, but air bubbles are generated and accumulate in the lubricating oil, reducing bearing life and reliability
Solution Approach 1:
The invention extracts air bubbles from the lubricating oil by providing a dedicated air bubble discharge path through the circulation hole. The circulation hole is positioned to allow air bubbles to be discharged from the first gap to the external environment, separating the harmful air bubbles from the lubrication system and preventing their accumulation that would otherwise reduce bearing reliability.
Solution Approach 2:
The circulation hole acts as an intermediary element between the first gap (where air bubbles are generated) and the external environment. It provides a controlled passage for air bubbles to exit the system, mediating the removal of harmful factors while maintaining the lubrication function of the bearing.
2Object-affected harmful factors
If the circulation hole is positioned close to the first gap, then air bubbles can be discharged effectively, but lubricating oil may leak through the circulation hole
Solution Approach 1:
The invention applies local quality by creating a tapered seal structure at the opening of the circulation hole. The seal surface has a specific taper angle (5° to 45°) that is optimized to prevent lubricating oil leakage while allowing air bubbles to pass through. This localized sealing structure addresses the leakage issue at the critical location without affecting the overall air bubble discharge function.
3Productivity
If the second gap is made larger to improve lubrication circulation, then lubrication efficiency increases, but the bearing structure becomes less stable
Solution Approach 1:
The invention changes the parameter of the second gap by making it extend over the entire periphery of the conical bearing member in the circumferential direction. This peripheral extension provides both improved lubrication circulation pathways and enhanced structural stability, as the gap is distributed around the entire bearing rather than being localized, thus maintaining bearing rigidity while enabling effective oil flow.
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 configuration enhances the suppression of air bubbles, improves lubrication circulation, and maintains the structural integrity of the bearing, thereby extending the product life and ensuring effective operation of the spindle motor.
Implementation Method 1
A circulation hole is formed in the conical bearing member, in which one end of the circulation hole opens to another end of the second gap and another end of the circulation hole opens to the space forming the tapered seal
Implementation Method 2
A space which forms a tapered seal is provided between the conical surface and the rotor
Data Source
AI summary
A fluid dynamic pressure bearing includes a conical bearing member having a conical bearing surface forming a first gap between a member constituting the rotor. A second gap connected to one end of the first gap and provided over the entire periphery of the shaft is formed between the conical bearing member and the shaft. A tapered seal portion is formed between the conical bearing member and the rotor. The conical bearing member is provided with a circulation hole that communicates the second gap and the tapered seal portion. The circulation hole communicates to another end of the first gap through a part of the tapered seal portion, so that the circulation hole and the other end of the first gap are spaced apart.