Development of High-Speed Gas Bearings for High-Power Density Microdevices

2002 ◽  
Vol 125 (1) ◽  
pp. 141-148 ◽  
Author(s):  
F. F. Ehrich ◽  
S. A. Jacobson
Keyword(s):  
Power Density ◽  
High Power ◽  
High Speed ◽  
Single Crystal Silicon ◽  
Small Scale ◽  
Crystal Silicon ◽  
Gas Bearings ◽  
Electromagnetic Devices ◽  
Air Turbine ◽  
Micro Machine

A 4.2-mm diameter silicon rotor has been operated in a controlled and sustained manner at rotational speeds greater than 1.3 million rpm and power levels approaching 5 W. The rotor, supported by hydrostatic journal and thrust gas bearings, is driven by an air turbine. This turbomachinery/bearing test device was fabricated from single-crystal silicon wafers using micro-fabrication etching and bonding techniques. We believe this device is the first micro-machine to operate at a circumferential tip speed of over 300 meters per second, comparable to conventional macroscale turbomachinery, and necessary for achieving high levels of power density in micro-turbomachinery and micro-electrostatic/ electromagnetic devices. To achieve this level of peripheral speed, micro-fabricated rotors require stable, low-friction bearings for support. Due to the small scale of these devices as well as fabrication constraints that limit the bearing aspect ratio, the design regime is well outside that of more conventional devices. This paper focuses on bearing design and test, and rotordynamic issues for high-speed high-power micro-fabricated devices.

Development of High-Speed Gas Bearings for High-Power-Density Micro-Devices

2001 ◽  
Author(s):  
F. F. Ehrich ◽  
S. A. Jacobson
Keyword(s):  
Power Density ◽  
High Power ◽  
High Speed ◽  
Single Crystal Silicon ◽  
Small Scale ◽  
Crystal Silicon ◽  
Gas Bearings ◽  
Electromagnetic Devices ◽  
Macro Scale ◽  
Micro Machine

A 4.2 mm diameter silicon rotor has been operated in a controlled and sustained manner at rotational speeds greater then 1.3 million rpm and power levels approaching 5 W. The rotor, supported by hydrostatic journal and thrust gas bearings, is driven by an air turbine. This turbomachinery/bearing test device was fabricated from single crystal silicon wafers using micro-fabrication etching and bonding techniques. We believe this device is the first micro-machine to operate at a circumferential tip speed of over 300 meters per second, comparable to conventional macro-scale turbomachinery, and necessary for achieving high levels of power density in micro-turbomachinery and micro-electrostatic/ electromagnetic devices. To achieve this level of peripheral speed, micro-fabricated rotors require stable, low friction bearings for support. Due to the small scale of these devices as well as fabrication constraints that limit the bearing aspect ratio, the design regime is well outside that of more conventional devices. This paper focuses on bearing design and test, and rotordynamic issues for high-speed high-power micro-fabricated devices.

scholarly journals Research on aerodynamic characteristics of two-stage axial micro air turbine spindle for small parts machining

2020 ◽  
Vol 12 (12) ◽  
pp. 168781402098437
Author(s):  
Liu Jiang ◽  
Guo Zhiping ◽  
Miao Shujing ◽  
He Xiangxin ◽  
Zhu Xinyu
Keyword(s):  
High Speed ◽  
Aerodynamic Characteristics ◽  
Maximum Efficiency ◽  
Two Stage ◽  
Output Torque ◽  
Air Turbine ◽  
Solid Foundation ◽  
Computational Fluid Dynamics Cfd ◽  
Micro Machine ◽  
Small Parts

In order to meet the requirements of output torque, efficiency and compact shape of micro-spindles for small parts machining, a two-stage axial micro air turbine spindle with an axial inlet and outlet is proposed. Based on the k-ω turbulence model of SST, the flow field and operation characteristics of the two-stage axial micro air turbine spindle were studied using computational fluid dynamics (CFD) combined with an experimental study. We obtained the air turbine spindle under different working conditions of the loss and torque characteristics. When the inlet pressure was 300 KPa, the output speed of the two-stage turbine was 100,000 rpm, 9% higher than that of a single-stage turbine output torque. The total torque reached 6.39 N·mm, and the maximum efficiency of the turbine and the spindle were 42.2% and 32.3%, respectively. Through the research on the innovative structure of the two-stage axial micro air turbine spindle, the overall performance of the principle prototype has been significantly improved and the problems of insufficient output torque and low working efficiency in high-speed micro-machining can be solved practically, which laid a solid foundation for improving the machining efficiency of small parts and reducing the size of micro machine tool.

Design and Characteristics of Microfocus X-ray Source with Sealed Tube and Transmissive Target on Diamond Window

2021 ◽  
Vol 79 (6) ◽  
pp. 631-640
Author(s):  
Takaaki Tsunoda ◽  
Takeo Tsukamoto ◽  
Yoichi Ando ◽  
Yasuhiro Hamamoto ◽  
Yoichi Ikarashi ◽  
...  
Keyword(s):  
Power Density ◽  
High Power ◽  
High Speed ◽  
Electronic Device ◽  
High Reliability ◽  
Electronic Devices ◽  
Lithium Ion ◽  
High Power Density ◽  
High Magnification ◽  
X Ray

Electronic devices such as medical instruments implanted in the human body and electronic control units installed in automobiles have a large impact on human life. The electronic circuits in these devices require highly reliable operation. Radiographic testing has recently been in strong demand as a nondestructive way to help ensure high reliability. Companies that use high-density micrometer-scale circuits or lithium-ion batteries require high speed and high magnification inspection of all parts. The authors have developed a new X-ray source supporting these requirements. The X-ray source has a sealed tube with a transmissive target on a diamond window that offers advantages over X-ray sources having a sealed tube with a reflective target. The X-ray source provides high-power-density X-ray with no anode degradation and a longer shelf life. In this paper, the authors will summarize X-ray source classification relevant to electronic device inspection and will detail X-ray source performance requirements and challenges. The paper will also elaborate on technologies employed in the X-ray source including tube design implementations for high-power-density X-ray, high resolution, and high magnification simultaneously; reduced system downtime for automated X-ray inspection; and reduced dosages utilizing quick X-ray on-and-off emission control for protection of sensitive electronic devices.

Research on a high power density mechanical-electrical-hydraulic regenerative suspension system for high-speed tracked vehicles

2021 ◽  
pp. 095440702110610
Author(s):  
Chao Wang ◽  
Weijie Zhang ◽  
Guosheng Wang ◽  
Yong Guo
Keyword(s):  
Power Density ◽  
High Power ◽  
High Speed ◽  
Excitation Amplitude ◽  
Suspension System ◽  
Level Energy ◽  
High Power Density ◽  
Damping Force ◽  
Tracked Vehicles ◽  
Energy Regeneration

High power density energy regeneration is one of the effective solutions to solve the contradiction between improving the damping performance and energy consumption of active suspension. The hydraulic commutator is used to realize hydraulic rectification and hydraulic variable speed/pump/motor with few teeth difference gear pairs is used to match the speed, combined with permanent magnet motor power generation and power supply to put forward kilowatt level high power density mechanical-electrical-hydraulic regenerative suspension system for high-speed tracked vehicles. The mathematical model and fluid-solid-thermo-magnetic multiphysics coupling model are built to analyze the damping performance and regenerative characteristics of the system under passive and semi-active working conditions. The simulation results show that the damping force of the system increases with the increase of the road excitation amplitude and the semi-active control can be realized by adjusting the duty cycle with the PWM control rectifier module. The high power density mechanical-electrical-hydraulic regenerative suspension system can realize kilowatt level energy regeneration, and the regenerative efficiency is more than 50% under low-frequency excitation. The temperature rise of the system is low during operation, which is helpful to improve the reliability and service life.

High-speed strained-single-crystal-silicon thin-film transistors on flexible polymers

2006 ◽  
Vol 100 (1) ◽  
pp. 013708 ◽  
Author(s):  
Hao-Chih Yuan ◽  
Zhenqiang Ma ◽  
Michelle M. Roberts ◽  
Donald E. Savage ◽  
Max G. Lagally
Keyword(s):  
Thin Film ◽  
Single Crystal ◽  
Thin Film Transistors ◽  
High Speed ◽  
Single Crystal Silicon ◽  
Flexible Polymers ◽  
Silicon Thin Film ◽  
Crystal Silicon

Optimization of Cutting Parameters for High Speed End Milling of Single Crystal Silicon by Diamond Coated Tools with Compressed Air Blowing Using RSM

2012 ◽  
Vol 576 ◽  
pp. 46-50 ◽  
Author(s):  
M.A. Mahmud ◽  
A.K.M. Nurul Amin ◽  
M.D. Arif
Keyword(s):  
Single Crystal ◽  
High Speed ◽  
End Milling ◽  
Single Crystal Silicon ◽  
Depth Of Cut ◽  
Machining Parameters ◽  
Crystal Silicon ◽  
Design Expert ◽  
Coated Tools ◽  
Optimization Of Cutting Parameters

This paper presents the thorough experimental analysis on high speed end milling of single crystal silicon using diamond coated tools. Experiments were conducted on CNC milling machine. The design of the experiments was based on the central composite design (CCD) technique of Design Expert software. Response Surface Methodology (RSM) was used to develop mathematical imperial model to establish a correlation between machining parameters (cutting speed, feed and depth of cut) and machined surface roughness in high speed end milling of single crystal silicon using 2mm diameter diamond coated tools. The optimum machining parameters were determined using the optimization tool of Design Expert software based on the desirability function. Finally, confirmation tests were performed to validate the developed model.

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