Closed Loop Performance of a Slotless Lorentz Self-Bearing Motor

2003 ◽  
Author(s):  
Hooi-Mei Chin ◽  
L. Scott Stephens
Keyword(s):  
High Speed ◽  
Closed Loop ◽  
Coupling Effect ◽  
Cross Coupling ◽  
Motor Design ◽  
High Speed Rotation ◽  
Bearing Stiffness ◽  
Speed Rotation ◽  
Power Densities ◽  
Tangential Directions

In previous work the authors presented a Lorentz self-bearing motor design targeted for precision pointing and smooth angular slewing applications. The motor also offers potential advantages when operated as a synchronous machine at high speed including larger power densities and shorter shafts. In this paper, the closed loop performance of the motor at low transient speeds (0–588 rpm) is presented. Using these results, several challenges to achieving high-speed rotation are identified and discussed. The most significant is the heavy cross coupling within the actuator which limits bearing stiffness and stability, and is amplified at rotor natural frequencies resulting in potential loss of levitation when passing through critical speeds. Of particular interest is the discovery of a significant cross coupling effect between the radial and tangential directions. A theory is put forth explaining this effect.

scholarly journals Sound Noise Generated from Ball Bearing in High Speed Rotation

1978 ◽  
Vol 21 (158) ◽  
pp. 1306-1310 ◽  
Author(s):  
Akio NAGAMATSU ◽  
Masaho FUKUDA
Keyword(s):  
High Speed ◽  
Ball Bearing ◽  
High Speed Rotation ◽  
Speed Rotation

Analysis of the Lubrication Regimes at the Small End and Big End of a Connecting Rod of a High Performance Motorbike Engine

2012 ◽  
Author(s):  
Luca Bertocchi ◽  
Matteo Giacopini ◽  
Daniele Dini
Keyword(s):  
Rotational Speed ◽  
High Speed ◽  
High Performance ◽  
Hydrodynamic Lubrication ◽  
Vertical Axis ◽  
Connecting Rod ◽  
Lubrication Regimes ◽  
High Speed Rotation ◽  
Speed Rotation ◽  
Squeeze Effect

In the present paper, the algorithm proposed by Giacopini et. al. [1], based on a mass-conserving formulation of the Reynolds equation using the concept of complementarity is suitably extended to include the effects of compressibility, piezoviscosity and shear-thinning on the lubricant properties. This improved algorithm is employed to analyse the performance of the lubricated small end and big end bearings of a connecting rod of a high performance motorbike engine. The application of the algorithm proposed to both the small end and the big end of a con-rod is challenging because of the different causes that sustain the hydrodynamic lubrication in the two cases. In the con-rod big end, the fluid film is mainly generated by the relative high speed rotation between the rod and the crankshaft. The relative speed between the two races forms a wedge of fluid that assures appropriate lubrication and avoids undesired direct contacts. On the contrary, at the con-rod small end the relative rotational speed is low and a complete rotation between the mating surfaces does not occurs since the con-rod only oscillates around its vertical axis. Thus, at every revolution of the crankshaft, there are two different moments in which the relative rotational speed between the con-rod and the piston pin is null. Therefore, the dominant effect in the lubrication is the squeeze caused by the high loads transmitted through the piston pin. In particular both combustion forces and inertial forces contribute to the squeeze effect. This work shows how the formulation developed by the authors is capable of predicting the performance of journal bearings in the unsteady regime, where cavitation and reformation occur several times. Moreover, the effects of the pressure and the shear rate on the density and on the viscosity of the lubricant are taken into account.

Research on Calibration Method of Tire Dynamic Balance Detection System

2012 ◽  
Vol 542-543 ◽  
pp. 828-832 ◽  
Author(s):  
Jing Fang Yang ◽  
Xian Ying Feng ◽  
Hong Jun Fu ◽  
Lian Fang Zhao
Keyword(s):  
High Speed ◽  
Detection System ◽  
Dynamic Balance ◽  
Calibration Method ◽  
Engineering Practice ◽  
Influence Coefficient ◽  
Quality Factors ◽  
High Speed Rotation ◽  
Speed Rotation ◽  
Upper Rim

Tire dynamic balance detection plays an important part in tire quality detection area. This paper uses the two-sided balance method to obtain the unbalance of the tire. According to the engineering practice, builds kinetic model and then introduces the calculating principle and operating procedures. In order to accurately determine the influence coefficient, a calibration method without tire is put forward. Further more, this new method is able to eliminate the unbalance caused by non-quality factors to some extent. But this method is presented based on the relative position invariance of the upper rim and lower rim, even both of them are under high-speed rotation situation. Finally, the experimental data acquired from both of the two methods are compared. The calibration method without tire is proved to be more feasible, efficient and accurate.

Improvement of Silver Recovery Efficiency by High-Speed Rotation

2003 ◽  
Vol 439 ◽  
pp. 156-162
Author(s):  
A. Da Camara ◽  
Joaquín Lira-Olivares ◽  
Soo Wohn Lee ◽  
H.D. Park ◽  
Y.S. Park
Keyword(s):  
High Speed ◽  
Recovery Efficiency ◽  
Silver Recovery ◽  
High Speed Rotation ◽  
Speed Rotation

High-speed Rotation and Speed Stability of the Sodium-driven Flagellar Motor inVibrio alginolyticus

1995 ◽  
Vol 251 (1) ◽  
pp. 50-58 ◽  
Author(s):  
Kazumasa Muramoto ◽  
Ikuro Kawagishi ◽  
Seishi Kudo ◽  
Yukio Magariyama ◽  
Yasuo Imae ◽  
...  
Keyword(s):  
High Speed ◽  
Flagellar Motor ◽  
High Speed Rotation ◽  
Speed Rotation ◽  
Speed Stability

Uniformity and repeatability of InAlN-barrier HEMTs growth by high-speed-rotation single-wafer MOCVD tool

2019 ◽  
Vol 509 ◽  
pp. 103-106 ◽  
Author(s):  
Masayuki Tsukui ◽  
Yasushi Iyechika ◽  
Hajime Nago ◽  
Hideshi Takahashi
Keyword(s):  
High Speed ◽  
High Speed Rotation ◽  
Speed Rotation

Mechanical Properties and Experimental Study of a Composite Polishing Plate during Super-High Polishing

2010 ◽  
Vol 135 ◽  
pp. 337-342
Author(s):  
Li Zhou ◽  
Shu Tao Huang ◽  
Li Fu Xu
Keyword(s):  
Chemical Reaction ◽  
High Speed ◽  
Equivalent Stress ◽  
Stress Distributions ◽  
Centrifugal Forces ◽  
X Ray ◽  
High Speed Rotation ◽  
Speed Rotation ◽  
Von Mises Equivalent Stress ◽  
Von Mises

A new composite polishing plate for polishing of CVD diamond films has been designed. The displacement and stress distributions of the high speed rotation polishing plate have been investigated due to centrifugal forces, and the polishing mechanism of super-high polishing has been analyzed by using X-ray photo-electron spectroscopy. The results showed that the displacements both in axial and radial increase with the increasing of the rotational speed. When the rotation speed reached to 1200 rad/s, the von Mises equivalent stress is about 242 MPa, which is safe for the composite polishing plate. Additional, the polishing mechanism is mainly the chemical reaction between carbon and titanium during the super-high speed polishing. At elevated temperature, the chemical reaction between oxygen and titanium, oxygen and carbon can also occur.

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