The influence of repeated high-energy engagements on the permeability of a paper-based wet clutch friction material

2017 ◽  
Vol 231 (12) ◽  
pp. 1574-1582
Author(s):  
Niklas Lingesten ◽  
Pär Marklund ◽  
Erik Höglund
Keyword(s):  
High Energy ◽  
Friction Material ◽  
Sliding Surface ◽  
Steel Core ◽  
Interface Surface ◽  
Clutch Engagement ◽  
Wet Clutch ◽  
Oil Flow ◽  
Contradictory Behavior ◽  
Test Cells

The behavior of a wet clutch during engagement is of great importance to the durability of the clutch and the drivability of a vehicle. While many different factors influence the engagement behavior, the focus of this paper is to investigate only one factor, the permeability of the wet clutch friction material. Two test cells for measuring the permeability of friction material mounted on clutch discs have been developed. The test cells were then used to examine the effect of clutch material ageing through clutch engagement on the permeability of the material. The tests were performed on full size friction discs including the steel core prior and subsequent to testing in a wet clutch engagement test rig. The ability of the friction material to allow for oil flow both through the sliding surface layer and the bulk of the material was measured. The results indicate that repeated clutch engagements will increase the bulk permeability. However, the repeated engagements will decrease the ability to pass fluid through the friction material sliding surface. This contradictory behavior could be explained by a combination of an increase in pore size through repeated compression and the surface glaze clogging of the friction interface surface pores.

A Numerical Study on the Influence of Grooves on Heat Transfer Performance of Wet Clutch

2012 ◽  
Vol 249-250 ◽  
pp. 517-522 ◽  
Author(s):  
Yu Long Lei ◽  
Jie Tao Wen ◽  
Xing Zhong Li ◽  
Cheng Yang
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Three Dimensional ◽  
Friction Material ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Linear Distribution ◽  
Exchange Performance ◽  
Wet Clutch ◽  
Oil Flow

In order to evaluate the efficacy of grooves on cooling performance of wet clutch, a numerical analysis based on the computational fluid dynamics (CFD) code FLUENT is presented in this study. This analysis is based on the numerical solution of the three-dimensional Navier-Stokes equation, coupled with the energy equation in the flow and the heat conduction equations in the friction material and the core disk. The turbulence characteristics were predicted using RNGk-ε model. The flow field and temperature distributions in radial grooves are obtained. It is shown that radial grooves possess the highest heat exchange performance at the entrance and is not linear distribution in the radial direction and cooling oil flow has a little effect on the highest temperature of friction plate. With the developed analysis method, it is possible to easily and quickly investigate the heat transfer behaviour of wet cluth with groove patterns.

Simulation of Wet Clutch Engagement on Electronically-Controlled Limited-Slip Differential (LSD) With Consideration of Degraded Clutch Performance

2010 ◽  
Author(s):  
Jaewon Choi ◽  
Mohsen Nakhaeinejad ◽  
Michael D. Bryant
Keyword(s):  
Friction Material ◽  
Dynamic Equations ◽  
Negative Slope ◽  
Combined Effects ◽  
Oil Oxidation ◽  
Friction Modifier ◽  
Clutch Engagement ◽  
Wet Clutch ◽  
Simulation Results ◽  
Parameter Values

A wet clutch is an integral part of the electronically controlled limited slip differential (eLSD) [1]. In this study, an eLSD model is constructed based on Deur et al.’s dynamic wet clutch model [2]. First the eLSD model including key dynamic equations and parameter values is discussed. The main culprits of clutch shudder include the negative slope of friction coefficient vs. slip speed curve, which is often caused by oil oxidation due to heat or an improper amount of friction modifier among others, and glazing of the friction linings [3,4]. In the second part, consequences of improper lubrication and glazed friction material during launch control of a vehicle equipped with eLSD will be studied based on simulations with lubrication data provided in [3]. The simulation results show that the combined effects of oxidized ATF and glazed friction material can cause clutch shudder.

Modeling and experimental research on engaging characteristics of wet clutch

2019 ◽  
Vol 71 (1) ◽  
pp. 94-101 ◽  
Author(s):  
Yanzhong Wang ◽  
Yuan Li ◽  
Yang Liu ◽  
Wei Zhang
Keyword(s):  
Contact Surface ◽  
Hydrodynamic Lubrication ◽  
Load Capacity ◽  
Lubricating Oil ◽  
Centrifugal Effect ◽  
Element Analysis ◽  
Content Type ◽  
Clutch Engagement ◽  
Wet Clutch ◽  
Engagement Process

PurposeTo gain in-depth understandings of engaging characteristics, the purpose of this paper is to improve the model of wet clutches to predict the transmitted torque during the engagement process.Design/methodology/approachThe model of wet clutch during the engagement process took main factors into account, such as the centrifugal effect of lubricant, permeability of friction material, slippage factor of lubricant on contact surface and roughness of contact surface. Reynolds’ equation was derived to describe the hydrodynamic lubrication characteristics of lubricant film between the friction plate and the separated plate, and an elastic-plastic model of the rough surfaces contact based on the finite element analysis was used to indicate the loading force and friction torque of the contact surface.FindingsThe dynamic characteristics of wet clutch engagement time, relative speed, hydrodynamic lubrication of lubricating oil, rough surface contact load capacity and transfer torque can be obtained by the wet clutch engagement model. And the influence of the groove shape and depth on the engaging characteristics is also analyzed.Originality/valueThe mathematical model of the wet clutch during the engagement process can be used to predict the engaging characteristics of the wet clutch which could be useful to the design of the wet clutch.

An investigation of dielectric breakdown on a pressurized, flowing oil switch - WITHDRAWN

2009 ◽  
Author(s):  
◽  
Peter A. Norgard
Keyword(s):  
Electric Field ◽  
Rise Time ◽  
High Performance ◽  
Dielectric Breakdown ◽  
High Energy ◽  
Operating Characteristics ◽  
University Of Missouri ◽  
Breakdown Electric Field ◽  
Alpha Olefin ◽  
Oil Flow

WITHDRAWN - [ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] In the not-so-distant future, a need is foreseen for a high-performance, compact switch that is capable of repetitively switching kilovolts to megavolts and several hundred joules, all while delivering a square pulse with a fast current rise time. Many industrial and military applications currently exist that could take advantage of these operating characteristics, and many more are surely to be developed in the coming years. The proposed approach to realizing the goal of producing a fast rise time, high voltage, high energy, repetitive switch technology is to employ a pressurized, flowing oil dielectric switching medium. Oil pressure and oil flow will be used to increase the rate of dielectric recovery following a high energy discharge, thus enabling a much higher operating repetition frequency; oil pressure will be utilized to control gaseous switching byproducts, and oil flow will be utilized to control solid and gaseous switching byproducts. The well-known increase in breakdown electric field strength with increasing oil pressure will be utilized to reduce the gap separation, thus reducing the inductance of the electrical arc and increasing the rise time of the current pulse produced during breakdown. An experiment was designed and undertaken to evaluate the complete statistical performance of the breakdown electric field of an emerging dielectric liquid, poly-[alpha]olefin, with respect to variations in oil pressure, oil flow rate, peak rate of rise of the voltage, and gap separation.

On the Formation of Hot Spots in Wet Clutch Systems

2001 ◽  
Vol 124 (2) ◽  
pp. 336-345 ◽  
Author(s):  
J. Y. Jang ◽  
M. M. Khonsari
Keyword(s):  
Hot Spots ◽  
Friction Material ◽  
Mechanical Seal ◽  
Comprehensive Model ◽  
Governing Equations ◽  
Thermoelastic Instability ◽  
Wet Clutch ◽  
Special Case

A comprehensive model is developed for analyzing the onset of thermoelastic instability in a wet clutch. For this purpose, appropriate governing equations are derived that take into account the porosity and deformability of the friction material. The effect of the thickness of the separator disk and that of the friction material are also included. The model is general and can be used to describe TEI in a variety of other systems such as in a mechanical seal, as a special case. A series of simulations are presented that predict the thermoelastic behavior of a wet clutch from an instability viewpoint.

Research on the Wet Clutch Engagement Torque

2014 ◽  
Author(s):  
Yingying Zhang ◽  
Changle Xiang
Keyword(s):  
Rough Surface ◽  
Automatic Transmission ◽  
Squeeze Film ◽  
Real Contact Area ◽  
Asperity Contact ◽  
Time Flow ◽  
Clutch Engagement ◽  
Wet Clutch ◽  
Lubrication Oil ◽  
Engagement Process

The driving performance of the vehicle with automatic transmission is influenced by the performance of the wet clutch directly. But at present it is still a challenge to build a reliable predictable model for the torque of the engagement process of the wet clutch. Focusing on the wet clutch of vehicle, this paper starts from mechanism analysis, and a modified Reynolds equation with the consideration of the centrifugal force of the squeeze-film is established. In the model, we can consider the speeds of the friction and separator plates independently. At the same time, flow factors have been used to research the impacts of rough surface on the flow of the lubrication oil. In the three-dimensional solution domain, the circumferential pressure gradient of lubrication oil is considered. The model is solved with the finite volume method. The simulation of the torque of the asperity contact calculates the real contact area changed with the engagement process, and the microscopic texture direction of rough surface is considered. Subsequently, the squeeze-film flow model is combined with the asperity contact model to create an integrated clutch engagement model. Finally, the influence of applied force, viscosity of lubrication oil, friction material, the depth of grooves and the width of the grooves are investigated. Based on the comparison with the experimental data, the performance of the proposed model is found satisfactory. Because in this model more detail properties of material and geometric features of the friction plate are include, the wet clutch model developed in this research can become a baseline model for the prediction of the engagement behavior of a real wet clutch. The present model may become an efficient alternative to laboratory testing and lead to designs that can not be envisioned by other approaches.

Robust predictive control design for optimal wet-clutch engagement

2012 ◽  
Author(s):  
A. Dutta ◽  
R. De Keyser ◽  
C. M. Ionescu ◽  
J. Stoev ◽  
G. Pinte ◽  
...  
Keyword(s):  
Predictive Control ◽  
Control Design ◽  
Clutch Engagement ◽  
Wet Clutch ◽  
Robust Predictive Control
Sign in / Sign up

Export Citation Format

Share Document