Hydrodynamic Bearing Rotary Device Friction Torque Reduction
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Solution Overview
Problem
Conventional hydrodynamic bearing rotary devices experience high friction torque and increased power consumption due to pressure differences causing lubricant leakage and large friction at thrust bearing portions, especially at low temperatures, leading to longer startup times and higher motor power requirements.
Innovation Solution
The design incorporates specific gap configurations between the sleeve, rotary shaft, and hub, where the second gap is larger than the first gap, and the fourth gap is larger than the second gap, utilizing surface tension to prevent lubricant leakage and reduce friction torque, along with a communication path for lubricant circulation and a tapered surface to enhance oil sealing, and the use of a sintered sleeve with a metal collar for improved accuracy and mass production capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thrust hydrodynamic grooves are designed with large diameter to prevent lubricant leakage, then lubricant sealing is improved, but friction torque at thrust bearing portion becomes large
Solution Approach 1:
The invention divides the bearing structure into two separate functional portions: a radial bearing portion with radial hydrodynamic grooves for lubricant circulation, and a thrust bearing portion with thrust hydrodynamic grooves for axial load support. This segmentation allows each portion to be optimized independently, preventing lubricant leakage through the radial portion while maintaining low friction at the thrust portion.
Solution Approach 2:
The invention applies different groove configurations to different locations: radial hydrodynamic grooves are formed on the outer peripheral surface of the rotary shaft for effective lubricant circulation, while thrust hydrodynamic grooves are formed on the thrust plate for axial load support. This local differentiation optimizes performance for each specific function while minimizing overall friction torque.
2Use of energy by moving object
If thrust hydrodynamic grooves are designed with large diameter to reduce friction, then friction torque is reduced, but lubricant leakage occurs due to pressure difference
Solution Approach 1:
The invention separates the lubricant sealing function from the friction reduction function by creating distinct radial and thrust bearing portions. The radial bearing portion with radial hydrodynamic grooves handles lubricant circulation and sealing, while the thrust bearing portion with thrust hydrodynamic grooves handles axial load support with minimal friction.
Solution Approach 2:
The invention introduces a communication path that connects the radial bearing portion and thrust bearing portion, allowing lubricant to flow between them. This intermediary connection ensures proper lubricant distribution and pressure management, preventing leakage while maintaining low friction operation.
3Device complexity
If conventional bearing design is used, then structural simplicity is maintained, but power consumption increases due to high friction torque
Solution Approach 1:
The invention divides the bearing into radial and thrust portions with distinct groove configurations, optimizing each for its specific function. This segmentation reduces overall friction torque and power consumption while maintaining a relatively simple overall structure that can be manufactured using conventional processes.
Solution Approach 2:
The invention optimizes geometric parameters including groove depth, groove width, and groove spacing in both radial and thrust portions. These parameter adjustments are made within conventional manufacturing capabilities to achieve reduced friction torque and lower power consumption without significantly increasing device complexity.
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 significantly reduces rotation friction torque, prevents lubricant leakage, and minimizes power consumption, resulting in a more efficient and reliable hydrodynamic bearing rotary device suitable for high-speed applications with reduced motor power requirements.
Implementation Method 1
generates a pumping pressure (hydrodynamic pressure) by hydrodynamic grooves during rotation
Implementation Method 2
utilizing surface tension to prevent lubricant leakage
Data Source
AI summary
A hydrodynamic bearing rotary device which can reduce rotation friction, and recording and reproducing apparatus including the same is provided. In the hydrodynamic bearing rotary device, such as hard disc devices, a rotary shaft having a hub on one end is provided in a bearing of a sleeve so as to be rotatable. Thrust hydrodynamic grooves are provided on the other end surface of the rotary shaft, to form a thrust bearing with the thrust plate. A communication path is provided in the sleeve. The second gap between the hub and the sleeve end surface is used as a flow channel and is connected to the communication path. In this way, the rotation friction torque of the thrust bearing can be made sufficiently small, and internal pressure in bonded portions of the rotary shaft or the bottom plate can be suppressed. Thus, the oil can be prevented from oozing out from a small space of the bonded surfaces. Furthermore, the hydrodynamic bearing can be made thin. These effects can be combined to realize an optimal hydrodynamic bearing rotary device.