The Effect of the Method of Compensation on Hydrostatic Bearing Stiffness

1961 ◽  
Vol 83 (2) ◽  
pp. 179-185 ◽  
Author(s):  
Stanley B. Malanoski ◽  
Alfred M. Loeb
Keyword(s):  
Film Thickness ◽  
Rapid Determination ◽  
Control Valve ◽  
Flow Control Valve ◽  
Absolute Value ◽  
Thrust Bearings ◽  
Hydrostatic Bearing ◽  
Supply Pressure ◽  
Bearing Stiffness

Capillary, orifice, and flow control valve compensation of hydrostatic thrust bearings is investigated theoretically with regard to the effect of these three methods of compensation on the stiffness of the lubricant film. Equations are derived which permit rapid determination of bearing stiffness at any given load and film thickness. When a hydrostatic bearing is made to operate at any given film thickness and load, it is found that at this load and film thickness no adjustment of the compensating element or supply pressure will alter the fact that ψvalve > ψorifice > ψcapillary where ψ equals the absolute value of stiffness. Furthermore, with fixed supply pressure and compensation, this stiffness relationship will remain the same for all practical values of load above and below the initial film thickness-load point.

A theoretical and experimental study on the stiffness of aerostatic thrust bearings with vacuum preloading

2018 ◽  
Vol 233 (2) ◽  
pp. 256-270 ◽  
Author(s):  
Ming Huang ◽  
Hailong Cui ◽  
Pinkuan Liu ◽  
Mengyang Li ◽  
Yueqing Zheng ◽  
...  
Keyword(s):  
Film Thickness ◽  
Vacuum Chamber ◽  
Pressure Ratio ◽  
Vacuum Pressure ◽  
Orifice Diameter ◽  
Absolute Pressure ◽  
Vacuum Preloading ◽  
Thrust Bearings ◽  
Supply Pressure ◽  
Bearing Stiffness

In this paper, the pressure distribution of aerostatic thrust bearings with vacuum pre-loading was investigated by solving the full Navier–Stokes equations based on the computational fluid dynamics method. The influences of the supply pressure, vacuum pressure, orifice diameter, and gas film thickness on the absolute pressure ratio were investigated. The finite difference method was used to study the effects of the vacuum chamber area, orifice diameter, orifice number, supply pressure, and vacuum pressure on the bearing stiffness. It is confirmed that the orifice diameter and film thickness had a great influence on the absolute pressure ratio, which increased with the reduction in the gas film thickness and the rise in the orifice diameter. The bearing stiffness can be improved by increasing the supply pressure, orifice number or vacuum chamber area or decreasing the orifice diameter or vacuum pressure, which provides useful guidance for the optimization design of aerostatic thrust bearings with vacuum preloading.

Static Characteristics of a Rectangular Hydrostatic Thrust Bearing With a Self-Controlled Restrictor Employing a Floating Disk

1993 ◽  
Vol 115 (2) ◽  
pp. 307-311 ◽  
Author(s):  
S. Yoshimoto ◽  
Y. Anno ◽  
M. Fujimura
Keyword(s):  
Flow Rate ◽  
Applied Load ◽  
Thrust Bearing ◽  
Static Characteristics ◽  
Hydrostatic Bearing ◽  
Supply Pressure ◽  
Wide Range ◽  
Bearing Stiffness ◽  
New Type ◽  
Very High

This paper proposes a new type of a self-controlled restrictor which can achieve a very high bearing stiffness in hydrostatic bearings. This self-controlled restrictor employs a floating disk to control the mass flow rate of the oil entering the bearing clearance according to changes of the applied load. Furthermore, a hydrostatic bearing with this restrictor can theoretically achieve an infinite stiffness when the mass of a floating disk is assumed to be zero. The static characteristics of a rectangular hydrostatic thrust bearing with this self-controlled restrictor are theoretically and experimentally investigated. It was consequently shown that the proposed hydrostatic thrust bearing can achieve a very high stiffness (nearly infinite stiffness) in a very wide range of applied load independent of supply pressure.

Analysis and Modification of the Design of Fluid Power Control System for the Improvement of Product Quality

2013 ◽  
Author(s):  
Tahany W. Sadak ◽  
Taha E. Mkawee
Keyword(s):  
Flow Control ◽  
Flow Rate ◽  
System Performance ◽  
Dynamic Performance ◽  
Control Valve ◽  
Operating Conditions ◽  
Flow Control Valve ◽  
Supply Pressure ◽  
System Designs ◽  
Proportional Flow

This research investigation is focused on providing system performance under different operating conditions, with special focus on variations in the supply pressure. The investigations have been carried out for different system designs. The analysis of the results introduces the effect of system designs on its static and dynamic performance. Also, the investigations provide the effect of variations of system operating conditions and load value. A hydraulic system has been designed with variable velocity, pressure and load. The detailed examination has been carried out on a system that consists of a hydraulic power supply unit, control valves (pressure control valve, flow control valve, throttle valve and directional control valve). We have investigated the effect of adding a flow control valve (FCV) in the chosen circuit and also replacing the FCV with a proportional flow control valve (PFCV). In order to study the effect of this valve on system performance we examine the role of change of operating conditions and loading values on the system performance. Thus the displacement and speed of the piston of the hydraulic cylinder has been experimented under different values of supply pressure, flow rate, and load. We make this investigation to develop the performance evaluation by replacing the (FCV) by proportional flow control valve (PFCV) via position control so that one can achieve the static and dynamic performance of the system more accurate. Apparent improvement in flow rate ranges from 8% to 29.5% and dynamic response from 30 to 64%. The results reveal that this methodology allows one to achieve high quality of the product.

Measurement of Multilayer Film Thickness Using X-Ray Fluorescence Spectrometer

2017 ◽  
Vol 726 ◽  
pp. 85-89
Author(s):  
Lei Zhang ◽  
Man Li ◽  
Hai Jian Li ◽  
Xin Song
Keyword(s):  
Thin Film ◽  
Film Thickness ◽  
Multilayer Film ◽  
Rapid Determination ◽  
Middle Layer ◽  
X Ray ◽  
Fundamental Parameters ◽  
Minimum Number ◽  
Fluorescence Spectrometer

Energy dispersive X-ray fluorescence spectrometry (EDXRF) allows a rapid determination of the concentration of elemental constituents or the thickness of thin film, it has been widely used in the industry of thin film thickness. But for multilayer film, especially the middle layer, with the absorption and enhance effect of other layers, the thickness and intensity of the middle layer is not a linear relationship. This paper reports a quantitative analysis of multilayer film thicknesses based on the use of EDXRF and fundamental parameters method. The thickness of multilayer film can be easily determined with the CTCFP software because it requires a minimum number of pure elementals only. Analysis of double-layer thin films using the CTCFP software shows that the inter-element and inter-layer X-ray absorptions and enhancements in a specimen have been determined properly. Results obtained on the standards confirmed the accuracy of the method.

Dynamic Analysis of High-Speed Hybrid Thrust Bearings

2013 ◽  
Vol 365-366 ◽  
pp. 304-308
Author(s):  
Lei Wang
Keyword(s):  
Dynamic Analysis ◽  
High Speed ◽  
Reynolds Equation ◽  
Thrust Bearing ◽  
Dynamic Performance ◽  
Orifice Diameter ◽  
Thrust Bearings ◽  
Supply Pressure ◽  
Bearing Stiffness ◽  
Stiffness And Damping

An analysis is conducted and solutions are provided for the dynamic performance of high speed hybrid thrust bearing. By adopting bulk flow theory, the turbulent Reynolds equation is solved numerically with the different orifice diameter and supply pressure. The results show that increasing supply pressure can significantly improve the bearing stiffness and damping, while the orifice diameters make a different effect on the bearing stiffness and damping.

On the Optimization of the Stiffness of Externally Pressurized Bearings

1962 ◽  
Vol 84 (1) ◽  
pp. 119-122 ◽  
Author(s):  
Marvin T. S. Ling
Keyword(s):  
Optimum Condition ◽  
Film Thickness ◽  
Incompressible Fluid ◽  
Compressible Fluid ◽  
Theoretical Studies ◽  
Proper Selection ◽  
Supply Pressure ◽  
Bearing Stiffness ◽  
Selection Of

This paper presents theoretical studies of the method of optimization of the stiffness of externally pressurized bearings. When an externally pressurized bearing is designed to operate at any given film thickness, it is found that the maximum bearing stiffness can be obtained by proper selection of the value of the ratio of recess to supply pressure, Pr/Ps. While various values of Pr/Ps can be attained by either varying the restrictor constant for a given film thickness or varying the film thickness for a given restrictor constant, the important quantity to vary in determining the optimum condition is the restrictor constant rather than the film thickness. For an incompressible fluid, the Pr/Ps value for which the bearing stiffness is optimized depends only on the type of compensation used, while for a compressible fluid it is slightly affected by exhaust pressure.

A semianalytical method for studying the performances of aerostatic thrust bearing

2018 ◽  
Vol 233 (4) ◽  
pp. 628-637
Author(s):  
Jianbo Zhang ◽  
Chunxiao Jiao ◽  
Donglin Zou ◽  
Na Ta ◽  
Zhushi Rao
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Film Thickness ◽  
Reynolds Equation ◽  
Thrust Bearing ◽  
Separation Of Variables ◽  
Orifice Diameter ◽  
Thrust Bearings ◽  
Supply Pressure ◽  
Semianalytical Method

The solution of Reynolds equation and computational fluid dynamics are widely employed for the lubrication performance analysis of aerostatic thrust bearing. However, the solution of Reynolds equation may be inaccurate and cannot present detailed performance near orifice, while computational fluid dynamics method has low computational efficiency with time consumption in mesh generation and solving Navier–Stokes equations. In order to overcome the drawbacks of Reynolds equation and computational fluid dynamics, based on the method of separation of variables, a semianalytical method is developed for describing the characteristics of aerostatic bearings available. The method of separation of variables considering the initial and viscous effect is more accurate than the Reynolds equation and can present detailed performance near orifice in the aerostatic thrust bearings, while method of separation of variables has great computational efficiency compared to computational fluid dynamics. Meanwhile, the pressure distribution calculated by method of separation of variables is compared to the published experimental data and the results obtained by computational fluid dynamics. The comparative results indicate validity of the method. Furthermore, the influences of flow and geometry parameters, such as supply pressure, orifice diameter, film thickness, and bearing radius, on the characteristics of aerostatic thrust bearings with single orifice are studied. The results show that there exists pressure depression phenomenon near orifice. The depression phenomenon is strengthened with increase of film thickness and supply pressure and decrease of orifice diameter and bearing radius, while the maximum speed increases with strengthening of pressure depression due to decrease of minimum local pressure near orifice. Moreover, the bearing capacity increases with increase of supply pressure, orifice diameter, and bearing radius and decreases with increase of film thickness, while mass flow rate increases with supply pressure, orifice diameter, and film thickness and it is not sensitive to bearing radius.

Hydrostatic bearings with multiport viscous pumps

2003 ◽  
Vol 217 (4) ◽  
pp. 333-342 ◽  
Author(s):  
H. A. Arafa ◽  
T. A. Osman
Keyword(s):  
Load Carrying Capacity ◽  
Pressure Source ◽  
Hydrostatic Bearing ◽  
Supply Pressure ◽  
Hydrostatic Bearings ◽  
Load Carrying ◽  
Viscous Pump ◽  
Bearing Stiffness ◽  
Flow Pressure ◽  
Good Agreement

An analysis of multirecess hydrostatic bearings with linear flow-pressure supply characteristics is presented. These characteristics can be obtained using either a constant supply pressure source with a laminar flow restrictor before each recess, or, as suggested in this paper, a multiport viscous pump. Analysis of the viscous pump-bearing system is made for odd numbers of recesses, and it is shown that a staggered or skip-one sequence of connection of the pump ports to the bearing recesses gives the least unbalanced reaction between the pump rotor/stator. The flow-pressure characteristics of viscous pumps with peripheral shrouded Rayleigh steps in a cylindrical configuration are derived and used to design a five-port pump to match a hydrostatic bearing. An experimental pump is designed, manufactured and tested, and the results obtained at one port show good agreement with the theoretically calculated values of pressure and flow. If this port is taken as representative of a pump, which is manufactured with higher accuracy, then the principle of having an effective multiport viscous pump is hereby validated. A simple means is suggested for making the bearing stiffness and load-carrying capacity insensitive to temperature/viscosity changes.

Diagnostics of Resistance Coefficients and Cavitation of Flow Control Valve

2015 ◽  
Vol 752-753 ◽  
pp. 980-987 ◽  
Author(s):  
Jana Jablonská ◽  
Milada Kozubková
Keyword(s):  
Flow Control ◽  
Flow Rate ◽  
Flow Characteristic ◽  
Rate Coefficient ◽  
Control Valve ◽  
Flow Control Valve ◽  
Flow Rate Coefficient ◽  
Resistance Coefficients ◽  
Valve Pressure

The paper deals with the determination of characteristic as dependence of the valve pressure drop on the flow rate, flow characteristic and cavitation conditions in case of water flow in the flow control valve. Emphasis is put on the utilization of simple, available relationships and measuring for identification of the basic valve coefficients, e.g. loss coefficient, flow rate coefficient and cavitation factor. These coefficients are used for designing of pipe circuits. In this paper there is defined methodology for determining those coefficients and is applied to the modified cone of flow control valve for verification the linear flow characteristic. It is necessary to consider the fact that in various countries the modifications of coefficients are preferred and it is therefore necessary to specify them.

The Effect of Different Designs on Performance of a Fluid Power Control System

2014 ◽  
Author(s):  
Tahany W. Sadak ◽  
Ahmed Fouly
Keyword(s):  
Hydraulic System ◽  
Dynamic Performance ◽  
Time Lag ◽  
Control Valve ◽  
Operating Conditions ◽  
Flow Control Valve ◽  
Hydraulic Systems ◽  
Supply Pressure ◽  
High Speeds ◽  
Hydraulic Servo

Hydraulic systems are characterized by their ability to import large forces at high speeds and are used in many industrial motion systems, also, in applications where good dynamic performance is important. This research concentrates on static and dynamic performance of a linear hydraulic system under different operating conditions in case of connecting an Electro Hydraulic Servo Valve (EHSV) and a Proportional Directional Flow Control Valve (PDFCV). High technology is used for measuring and recording the experimental results which achieves accurate evaluations. Experiments have been conducted in case of no-load and under load 5560 N. Supply pressure has been changed from 10 up to 50 bar. Effect of pressure and load variation on hydraulic system performance has been studied. It is concluded that increasing the load decreases the bandwidth frequency, but increasing the supply pressure increases the bandwidth frequency. Comparing the time lag of the system considering connecting the (EHSV) with that in case of connecting (PDFCV), it’s observed that in the present investigation the time lag improves by about 86.4% in case of free-load and by about 95.3% in case of system loaded.

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