scholarly journals Analysis of Dynamic Engaged Characteristics of Wet Clutch in Variable Speed Transmission of a Helicopter

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1474
Author(s):  
Heyun Bao ◽  
Tongjing Xu ◽  
Guanghu Jin ◽  
Wei Huang
Keyword(s):  
Film Thickness ◽  
Bearing Capacity ◽  
Friction Torque ◽  
Rate Of Change ◽  
Lubricating Oil ◽  
Oil Film ◽  
Capacity Model ◽  
Wet Clutch ◽  
Friction Plate

The working principle and motion process of an aviation wet clutch are analyzed. The initial velocity before the friction pair engaged is solved. The transient Reynolds equation is modified, and an oil film bearing capacity model and a micro-convex bearing capacity model are derived. The film thickness equation between N friction pairs and a pressure-plate is derived. A dynamic engaged model of springs, pistons, friction pairs, and pressure plates are established. The torque balance equation is established of two pairs of friction pairs. The friction torque, rate of change in the oil film, and law of relative change in speed are obtained. The results demonstrate that the spring preload and the viscosity of the lubricating oil have a significant influence on the engagement characteristics. Increasing the quality of the friction plate will reduce the time of engagement, whereas the quality of the friction plate has slight effect on the friction torque characteristics and oil film thickness. The initial speed generated by the collision process will reduce the output speed, sharply increase the torque peak at the lock, and increase the shift shock.

scholarly journals Influence of the Temperature of Lubricating Oil on the Friction Torque of Cu-based Wet Clutch

2020 ◽  
Vol 56 (20) ◽  
pp. 155
Author(s):  
YU Liang ◽  
MA Biao ◽  
CHEN Man ◽  
ZHANG Cunzhen ◽  
WU Junfeng
Keyword(s):  
Friction Torque ◽  
Lubricating Oil ◽  
Wet Clutch

Experimental study on line-contact elastohydrodynamic grease lubrication properties of surface-textured rollers

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Fuqin Yang ◽  
Dexing Hu ◽  
Qianhao Xiao ◽  
Shun Zhao
Keyword(s):  
Film Thickness ◽  
Surface Texture ◽  
Inhibitory Effect ◽  
Lubricating Oil ◽  
Line Contact ◽  
Grease Lubrication ◽  
Content Type ◽  
Oil Film ◽  
Crown Width ◽  
Lubrication Properties

Purpose This paper aims to study line-contact elastohydrodynamic grease lubrication properties of surface-textured rollers as well as the effect of different crown widths (dw) on oil film thickness under textured conditions. Design/methodology/approach The laser processing method was used to make the micro-texture on the surface of GCr15 steel rollers; lithium grease was used as the lubricant, and line-contact elastohydrodynamic grease lubrication experiments under pure sliding conditions were performed on light interference elastohydrodynamic-lubricated experimental table. Findings The results show that the line-contact elastohydrodynamic grease lubrication is closely related to the textured crown width of steel rollers. At low speeds and light loads, texturing has an inevitable inhibitory effect on the formation of the lubricating oil film, and the smaller the width of the crown area, the more obvious the inhibitory effect, which is not conducive to the improvement of the lubrication condition. At high speeds and high loads, the textured roller with dw = 1 mm has the largest oil film thickness and shows better lubrication performance. Originality/value At present, there is little research on the surface texture of line-contact friction pairs. This work explores the effect of different textured crown width on the lubricating properties of line-contact elastohydrodynamic grease lubrication by experiment. It provides a new theoretical basis for the subsequent practical application of surface texture technology.

Application of dynamic mesh technology in the oil film flow simulation for hydrostatic bearing

2019 ◽  
Vol 71 (1) ◽  
pp. 146-153
Author(s):  
Yanqin Zhang ◽  
Zhiquan Zhang ◽  
Xiangbin Kong ◽  
Rui Li ◽  
Hui Jiang
Keyword(s):  
Film Thickness ◽  
Flow Velocity ◽  
Manufacturing Industry ◽  
Dynamic Mesh ◽  
Lubricating Oil ◽  
Thickness Variation ◽  
Content Type ◽  
Oil Film ◽  
Rotating Speed ◽  
Hydrostatic Bearing

Purpose The purpose of this paper was to obtain the lubrication characteristics of heavy hydrostatic bearing in heavy equipment manufacturing industry through theoretical analysis and numerical simulation. Design/methodology/approach This paper discusses the influence of oil film thickness variation on velocity field, outlet-L and outlet-R flow velocity under the hydrostatic bearing running in no-load 0 N, load 400 KN, full load 1,500 KN and rotating speeds of 10 r/min, 20 r/min, 30 r/min, 40 r/min, 50 r/min and 60 r/min, by using dynamic mesh technology and FLUENT software. Findings When the working table rotates clockwise, in the change process of oil film thickness, the fluid flow pattern of the lubricating oil at the edge of the sealing oil is the rule of laminar flow, and the oil cavity has a vortex. The outlet-R flow velocity becomes higher and higher by increasing the bearing load and working table speed, and the flow velocity increases with the decrease in oil film thickness; the outlet-L flow velocity increases with the decrease in oil film thickness under low rotating speed (less than 10 r/min) condition and decreases with the decrease of oil film thickness under high rotating speed (more than 60 r/min) condition. Originality/value The influence of the oil film thickness on the flow state distribution of the oil film was analyzed under different working conditions, and the influence rules of oil film thickness on the flow velocity of hydrostatic bearing oil pad was obtained by using dynamic mesh technology.

Numerical Investigation of the Flow in a Hydrodynamic Thrust Bearing With Floating Disk

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Magnus Fischer ◽  
Andreas Mueller ◽  
Benjamin Rembold ◽  
Bruno Ammann
Keyword(s):  
Film Thickness ◽  
Thrust Bearing ◽  
Rotational Velocity ◽  
Control Unit ◽  
Axial Direction ◽  
Lubricating Oil ◽  
Temperature Dependent ◽  
Temperature Dependent Viscosity ◽  
Axial Thrust ◽  
Oil Film

In this paper we present a novel method for the numerical simulation of flow in a hydrodynamic thrust bearing with floating disk. Floating disks are commonly employed in turbochargers and are situated between the thrust collar, which is rotating at turbocharger speed, and the static casing. A floating disk reduces wear, improves the skew compensating capacity of the bearing, and is freely movable in the axial direction. The simulation model presented combines a commercial flow solver (ANSYS CFX) with a control unit. Based on physical principles and a predefined axial thrust, the control unit automatically sets the rotational speed of the floating disk, the mass flow of the oil supply, and the oil film thickness between the rotating disk and the casing wall and collar, respectively. The only additional inputs required are the temperature and the pressure of the oil at the oil feed and the turbocharger speed. The width of the computational grid of the thin lubricating oil film in the gaps is adjusted using a mesh-morphing approach. The temperature-dependent variation in viscosity is included in the model. The calculated solution of the flow field in the domain, the oil film thickness, and the resulting rotational velocity of the floating disk are validated against experimental data and demonstrate favorable agreement. The influence of uncertainties in the measurements and the behavior of the systems are thoroughly investigated in parametric studies that reveal the key influencing factors. These are the temperature-dependent viscosity of the oil, the axial thrust, and turbulence effects in the supply grooves and ducts of the floating disk. Using the model presented here, it is now possible to predict design variants for this type of bearing.

Experimental Analysis on Oil Film Properties of Plane Port Pair in Axial Piston Machine

2013 ◽  
Vol 681 ◽  
pp. 169-174
Author(s):  
Bin Wang ◽  
Shi Long Chen ◽  
Zhi Feng Ye
Keyword(s):  
Film Thickness ◽  
High Performance ◽  
Lubricating Oil ◽  
Frictional Torque ◽  
Fluid Temperature ◽  
Film Properties ◽  
Oil Film ◽  
Supply Pressure ◽  
Axial Piston Machine ◽  
Axial Piston

To find some rules keeping good lubrication condition for plane port pair in high-performance axial piston pump or motor, especially in the very severe applications, a new test rig was built up to simulate the operational principle of port pair, and to form the lubricating oil film for representative parameter acquisition. This rig is principally characterized by supply pressure up to 30 MPa, accurate control of oil film thickness by separate oil circuit design and electrohydraulic feedback control. The tested oil film working properties was analyzed by comparison with theoretical or simulation references. Experiments show that film balance time and thickness are two key parameters for describing oil film properties, and that working condition factors such as supply pressure, lubricating fluid temperature also notably affects the film thickness and its configuration, but they don’t show equivalent action. Lubrication effects can be valued by the tested frictional torque change of port pair.

The Significance of Oil Thermal Properties on the Performance of a Tilting-Pad Thrust Bearing

2001 ◽  
Vol 124 (2) ◽  
pp. 377-385 ◽  
Author(s):  
Sergei B. Glavatskih ◽  
Michel Fillon ◽  
Roland Larsson
Keyword(s):  
Thermal Properties ◽  
Film Thickness ◽  
Thrust Bearing ◽  
Friction Torque ◽  
Temperature Fields ◽  
Outer Diameter ◽  
Oil Film ◽  
Tilting Pad ◽  
Viscosity Grade ◽  
Mineral Base

This paper is a report into an experimental and theoretical investigation of the effect of oil thermal properties on the performance of a tilting-pad thrust bearing. Three oils, namely poly-α-olefin, ester and mineral base, were chosen for this study. These oils all have same viscosity grade (ISO VG46) but differ in their rates of viscosity variation with temperature and in their heat capacity and thermal conductivity values. Mineral base oil of a higher viscosity grade (ISO VG68) was also analyzed for comparison. Experimental data were obtained from an equalizing tilting-pad thrust bearing with an outer diameter of 228.6 mm operating in a flooded lubrication mode. Simultaneous measurements of pad and collar temperatures, friction torque, pressures and oil film thickness were taken. In the tests, oil supply temperature and flow rate were held constant for all load-speed combinations. The theoretical analysis of oil performance was based on a three-dimensional TEHD model. In the analysis, thermal effects were locally taken into account and heat transfer into the pads was considered. The displacements of the active surface of the pads, due to pressure and temperature fields, were determined. The effect of initial pad crowning on the oil film thickness is discussed. Experimental and theoretical results are compared and analyzed in terms of the inlet and outlet oil film thickness, bearing operating temperature and power loss.

The Simple Model of the Oil Film Thickness between Piston Ring and Cylinder

2010 ◽  
Vol 97-101 ◽  
pp. 1239-1242
Author(s):  
De Liang Liu ◽  
Hui Biao Lu ◽  
C.G. Sun
Keyword(s):  
Film Thickness ◽  
Internal Combustion Engine ◽  
Piston Ring ◽  
Reynolds Equation ◽  
Combustion Engine ◽  
Friction Pair ◽  
Internal Combustion ◽  
Theoretical Research ◽  
Lubricating Oil ◽  
Oil Film

Piston ring-cylinder is one of the most important friction pair of internal combustion engine，the lubricating state between them has decided internal combustion engine lubrication quality. So the theoretical research to the lubricating characteristics of the piston-ring group, especially the calculation of the lubricating oil film thickness is very important. The oil film thickness between piston-ring and cylinder is studied by calculation method. The calculation program is developed with average Reynolds equation taken the surface topography, viscosity-temperature effect, viscosity-pressure effect, extrusion effect and other factors into account. The position of oil outlet point is preinstalled, the full lubrication is assumed, and the Reynolds equation is solved by full pivot element gausses elimination approach, so the iterative course and calculation workload are reduced, and a great lot of the calculating time is saved, the oil film thickness of full period can be more accurately predicted by the ordinary PC within 30 minutes, which can supply quick effective evidence for next calculation and analysis.

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