Fluid Dynamic Bearing Lid Member Fixation Surface Design
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Solution Overview
Problem
Conventional fluid dynamic bearing devices face challenges in reducing axial dimensions and enhancing durability due to insufficient fixing force between the lid member and the housing, leading to potential lubricant leakage and accuracy issues under impact loads.
Innovation Solution
The design includes a lid member with a plate portion and a fixation surface having an axial dimension larger than the plate portion, allowing for a thinner form while increasing the fixing force, and an open space that can be filled with lubricant or adhesive to enhance sealing and fixation, thereby downsizing the device and improving durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the lid member is thinly-formed to reduce axial dimensions, then the device size is reduced, but the fixation area between the lid member and housing is reduced, leading to insufficient fixing force
Solution Approach 1:
The invention transitions from a single-layer thin plate structure to a multi-layer structure by adding a fixation surface that extends in the axial direction. This dimensional extension increases the fixation area without significantly increasing the overall thickness of the lid member, thereby resolving the contradiction between thinning and sufficient fixation strength.
Solution Approach 2:
The lid member is segmented into distinct functional portions: a plate portion for closing the housing opening and a fixation surface for securing the lid member to the housing. This segmentation allows each portion to be optimized independently - the plate portion remains thin for size reduction while the fixation surface provides adequate area for strong attachment.
2Volume of moving object
If the fixation area is reduced due to thinning the lid member, then the device becomes more compact, but the fixing force is insufficient under impact loads
Solution Approach 1:
By extending the fixation surface in the axial direction rather than increasing the radial or circumferential dimensions, the invention increases fixation area without proportionally increasing overall device volume. This allows improved reliability under impact loads while maintaining compact dimensions.
Solution Approach 2:
The invention applies local quality enhancement by concentrating the increased fixation area specifically at the fixation surface where it is needed for durability, while keeping the rest of the lid member thin. This localized enhancement improves impact resistance without compromising overall device compactness.
3Length of moving object
If the lid member is made thinner for downsizing, then the device axial dimension is reduced, but displacement of the lid member relative to the housing occurs under impact load
Solution Approach 1:
The fixation surface extends in the axial direction to provide increased area for attachment, creating stronger mechanical bonding between the lid member and housing. This enhanced bonding prevents relative displacement under impact loads while maintaining the thin profile of the main lid body.
Solution Approach 2:
The fixation surface is designed with sufficient area in advance to anticipate and withstand impact loads before they occur. This preliminary design ensures that the lid member remains stably positioned during normal operation and under transient impact conditions.
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 effectively increases the fixing force between the lid member and the housing, allowing for a more compact and durable fluid dynamic bearing device while preventing lubricant leakage and maintaining bearing performance.
Implementation Method 1
a radial bearing gap facing with an outer peripheral surface of the shaft member and having one end communicating with a space closed by means of the lid member, the radial bearing gap including an oil film with which the shaft member is rotatably supported
Data Source
AI summary
A lid member (10) is formed in a cup-like shape while having a plate portion (10a) and a cylindrical fixed portion (10b) axially protruding from an outer peripheral end of the plate portion (10a). An outer peripheral surface (10b1) of the fixed portion (10b), which serves as a fixation surface (B), is fixed to an inner peripheral surface (7a) of a housing (7) as an outer member (A). An axial dimension of the fixation surface (B) is larger than a thickness of the plate portion (10a), and hence it is possible to thinly-form the plate portion (10a) and to increase a fixing force between the lid member (10) and the housing (7). As a result, an axial dimension of a fluid dynamic bearing device can be reduced and durability thereof can be simultaneously increased.