Influence of Paper-Based Friction Material Visco-Elasticity on the Performance of a Wet Clutch

1997 ◽  
Author(s):  
Takayuki Matsumoto
Keyword(s):  
Friction Material ◽  
Wet Clutch

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.

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.

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.

scholarly journals Influence of oxidation of automatic transmission fluids (ATFs) and sliding distance on friction coefficients of a wet clutch in the running-in stage

Friction ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 401-414
Author(s):  
Leonardo Israel Farfan-Cabrera ◽  
Ezequiel Alberto Gallardo-Hernández ◽  
Manuel Vite-Torres ◽  
Jesús Gilberto Godínez-Salcedo
Keyword(s):  
Automatic Transmission ◽  
Viscosity Index ◽  
Composite Plates ◽  
Friction Material ◽  
Friction Coefficients ◽  
Surface Flattening ◽  
Wet Clutch ◽  
Torque Capacity ◽  
Pin On Disk ◽  
Sliding Distance

AbstractIn this paper, the influence of oxidation of automatic transmission fluids (ATFs) and sliding distance on the friction coefficients of a wet clutch in approached running-in conditions was investigated. The ATFs were oxidized by a laboratory process approaching oxidation occurred in actual ATFs. Oxidation was evaluated by means of increase in carbonyl compounds and depletion of zinc dialkyldithiophosphates (ZDDPs) additives. Also, the changes in kinematic viscosity and viscosity index were evaluated. Pin-on-disk tests were conducted to replicate the actual sliding contact in a wet clutch. The pin specimens were cut from friction material composite plates and the disks were actual steel separators both from an automotive wet clutch. Friction coefficient, μ, was measured at progressive sliding velocity, ν, to obtain μ-ν curves at 26 and 100 ΰC. Three μ-ν tests were consecutively run using the same pair of specimens and oil. The cumulative sliding distance for each μ-ν test generated surface flattening using the oils. The friction coefficients of the wet clutch increased due to the ATFs oxidation meanwhile the dμ/dυ values decreased in most cases. It suggests that ATF oxidation can enhance torque capacity of the wet clutch, but it could reduce anti-shudder property. Progressive sliding distance improved the slopes in the μ-ν results using fresh ATFs meanwhile it generated a slope decrease by using aged ATFs.

Parametric analysis of wear factors of a wet clutch friction material with different groove patterns

2017 ◽  
Vol 231 (8) ◽  
pp. 1056-1067 ◽  
Author(s):  
M Li ◽  
MM Khonsari ◽  
DMC McCarthy ◽  
Joakim Lundin
Keyword(s):  
Temperature Field ◽  
Material Properties ◽  
Parametric Analysis ◽  
Wear Test ◽  
Friction Material ◽  
Asperity Contact ◽  
Wet Clutch ◽  
Engagement Process ◽  
Insight Into ◽  
Friction Lining

The experimentally observed, two-stage wear in the wet clutch friction material is directly related to temperature and engagement load. To gain insight into the durability of the friction lining, an extensive parametric analysis of the factors is performed that takes into account different groove patterns (waffle shape, radial, and spiral), internal structure and material properties. The temperature field is predicted using a thermohydrodynamic analysis with the consideration of the asperity contact stress during the engagement process. The results should be useful to facilitate the industrial design of friction lining by avoiding costly wear test.

20608 Changes in flow properties due to friction material shape of the wet clutch

2015 ◽  
Vol 2015.21 (0) ◽  
pp. _20608-1_-_20608-2_
Author(s):  
Yuto SAKURAI ◽  
Takuma KATO ◽  
Daiki SHINOBU
Keyword(s):  
Friction Material ◽  
Flow Properties ◽  
Wet Clutch
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