Spindle Motor Helium Sealing via Segmented Shaft
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Solution Overview
Problem
Spindle motors in disk drives face challenges in maintaining a sealed environment due to the leakage of low-density gases like helium, which affects the precision and reliability of data recording by allowing gas to escape from the housing.
Innovation Solution
The spindle motor design incorporates a shaft with a non-through hole portion, first and second connection channels, and a sealing member between the screw hole portion and the first connection channel, creating a continuous space that prevents gas leakage by using a combination of press-fitting and adhesive sealing to secure the shaft to the base, ensuring a tight seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shaft is fixed in a through hole defined in the base, then the shaft can be securely mounted, but it is not easy to ensure sufficient sealing of the region where the base and shaft are fixed
Solution Approach 1:
The shaft is divided into multiple sections: a through-hole portion that passes through the base, a non-through hole portion that extends downward from the upper end, and connection channels within the non-through hole portion. This segmentation allows the sealing member to be positioned specifically in the non-through hole portion, creating effective sealing without complicating the overall structure.
Solution Approach 2:
A sealing member is introduced as an intermediary element between the shaft and the base. The sealing member is arranged in the non-through hole portion of the shaft, preventing gas leakage through the connection between the shaft and base while maintaining structural simplicity.
2Reliability
If the interior of the HDD is filled with low-density gas such as helium, then resistance against disk and head during rotation is reduced, but the gas tends to easily leak out due to extremely small molecules
Solution Approach 1:
The sealing member acts as an intermediary barrier that prevents helium gas from leaking through the shaft-base connection. By positioning the sealing member in the non-through hole portion, the patent effectively blocks the escape path for helium molecules while maintaining the low-density gas environment necessary for precise data recording.
Solution Approach 2:
The sealing member functions as a flexible barrier that conforms to the shaft structure, creating an effective seal against helium gas leakage. This flexible sealing approach is particularly effective for preventing escape of gases with extremely small molecules like helium.
3Ease of manufacture
If the shaft is fixed in a through hole, then mounting is simplified, but gas can leak through the connection region between base and shaft
Solution Approach 1:
The shaft structure is segmented into a through-hole portion for simple mounting and a non-through hole portion for sealing. The connection channels are embedded within the non-through hole portion, allowing gas flow while maintaining sealing at the critical shaft-base interface. This segmentation achieves both mounting simplicity and gas leakage prevention.
Solution Approach 2:
Different portions of the shaft are given different functions: the through-hole portion provides simple mounting, the non-through hole portion provides sealing, and the connection channels provide gas flow paths. This local differentiation of quality and function resolves the contradiction between ease of manufacture and prevention of gas leakage.
Data Source
AI summary
A spindle motor includes a shaft extending in an axial direction, and a base portion configured to define a portion of a housing, and including a through hole in which the shaft is inserted. The shaft includes a non-through hole portion, a first connection channel, and a second connection channel extending from the non-through hole portion in a radial direction. An upper portion of the hole portion includes a screw hole portion including a screw thread. A minimum diameter of the screw thread is greater than an inside diameter of the hole portion. A sealing member is located between the screw hole portion and the first connection channel.