Fluid Dynamic Bearing with Void Section and Optimized Gap
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing fluid dynamic bearing devices with fully-filled structures require complex and costly processes for oil filling and management, making them difficult to manufacture at a low cost while maintaining desired bearing performance.
Innovation Solution
A fluid dynamic bearing device with a housing having a void section, where the radial and thrust bearing gaps are filled with lubricating oil, and the gap widths are optimized to prevent oil leakage, allowing for easier and less costly oil injection and assembly, with a communication path to discharge air and maintain oil levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire interior space of the housing is filled with lubricating oil (fully-filled structure), then the bearing performance is maintained and the sealing space functions as a buffer for temperature changes, but the oil filling process becomes complicated and costly, and the oil level management requires high accuracy
Solution Approach 1:
The invention extracts the lubricating oil from the entire interior space of the housing, leaving a void section. Only the radial bearing gap and bottom gap are filled with oil. This eliminates the need for complex vacuum impregnation processes and high-precision oil level management while maintaining bearing performance through proper oil placement in critical areas.
2Object-generated harmful factors
If the radial gap width is made large to prevent oil leakage during shaft insertion, then oil leakage is prevented, but the gap width must be carefully controlled within specific ranges to maintain bearing performance
Solution Approach 1:
The invention specifies a particular range for the radial gap width (0.03mm to 0.3mm) to optimize both oil leakage prevention and bearing performance. This parameter change allows the radial gap to serve dual functions: preventing oil leakage during shaft member insertion while maintaining adequate bearing performance without requiring overly precise manufacturing tolerances.
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 enables the fluid dynamic bearing device to be manufactured at a lower cost while maintaining desired bearing performance by simplifying the oil injection process and preventing oil leakage, ensuring stable operation.
Implementation Method 1
a radial bearing portion for supporting the shaft member in a radial direction by an oil film of lubricating oil formed in a radial bearing gap
Implementation Method 2
when a shaft member is inserted along an inner periphery of the bearing sleeve, air which is present in the interior space of the housing is pumped into the radial gap, and thus the lubricating oil leaks out to an outside along with the shaft member
Data Source
Figure 1~2
Figure 3~4
Figure 5A~5B
AI summary
A fluid dynamic bearing device (1) including: a bearing sleeve (8) fixed to an inner periphery of a housing (7); a shaft member (2) removably inserted along an inner periphery of the bearing sleeve (8); an annular member (9) having an inner peripheral surface (9a) for defining a radial gap (Ga) together with an outer peripheral surface (2a) of the shaft member (2); and radial bearing portions (R1, R2) and a thrust bearing portion (T) for supporting the shaft member (2). At least the radial bearing gap (Gr) at each of the radial bearing portions (R1, R2), and a bottom gap (Gb) having the thrust bearing portion (T) received therein are filled with lubricating oil (11). A void section is formed in an interior space of the housing (7). Assuming that d1 represents a gap width of the radial bearing gap (Gr) and d2 represents a gap width of the radial gap (Ga), a relationship of 30d1≤d2≤250d1 is satisfied.