Study on the Change of Friction Characteristics with Use In the Wet Clutch of Automatic Transmission

1997 ◽  
Author(s):  
Kohei Matsuo ◽  
Shin Saeki
Keyword(s):  
Automatic Transmission ◽  
Friction Characteristics ◽  
Wet Clutch

Optimizing the Smoothness and Temperatures of a Wet Clutch Engagement Through Control of the Normal Force and Drive Torque

1999 ◽  
Vol 122 (1) ◽  
pp. 119-123 ◽  
Author(s):  
Mikael Holgerson
Keyword(s):  
Temperature Rise ◽  
Normal Force ◽  
Dynamic Performance ◽  
Automatic Transmission ◽  
Test Rig ◽  
Friction Characteristics ◽  
Drive Torque ◽  
Clutch Engagement ◽  
Wet Clutch ◽  
Transmission Gear

Automatic transmission gear shifts are handled by wet clutches, which determine the smoothness. The clutch face temperatures during the engagements are often an important parameter for the total clutch life. A wet clutch test rig has been used to evaluate how a wet clutch engagement can be improved in terms of smoothness and temperature. This was performed with control based upon knowledge about friction characteristics and dynamic performance. The parameters used for control were the drive torque and the normal force on the clutch. By drive torque shut-off and reduced normal force the torque variations were greatly reduced and the temperature rise was decreased by 37%. [S0742-4787(00)01601-5]

scholarly journals Evaluation of thermo-oxidized Jatropha bio-oil in lubrication of actual wet clutch materials

2020 ◽  
pp. 135065012098146
Author(s):  
Leonardo I Farfan-Cabrera ◽  
Ezequiel A Gallardo-Hernández ◽  
José Pérez-González ◽  
Benjamín M Marín-Santibáñez ◽  
Roger Lewis ◽  
...  
Keyword(s):  
Automatic Transmission ◽  
Viscosity Index ◽  
Jatropha Oil ◽  
Oxidative Aging ◽  
Lubrication Regime ◽  
Viscosity Increase ◽  
Bio Oil ◽  
Wet Clutch ◽  
Transmission Fluid ◽  
Pin On Disk

In this work, an assessment of the performance of thermo-oxidated Jatropha oil as a lubricant for actual wet clutch materials was performed and compared with a commercial automatic transmission fluid. For this, Jatropha oil, a commercial automatic transmission fluid and a blend of 20 vol% Jatropha oil–80 vol% automatic transmission fluid were subjected to thermo-oxidative aging at 26 °C and 100 °C, followed by a pin-on-disk testing with disk samples from an actual wet clutch. Evaluation of the film thickness at the sliding interface resulted in a boundary lubrication regime for all the tests. The changes in oxidation, viscosity, and a viscosity index of the samples were evaluated along with friction coefficients at various sliding speeds. Jatropha oil was the most sensitive to thermo-oxidation. Jatropha oil and the blend showed a higher viscosity increase than automatic transmission fluid with thermo-oxidation, while the viscosity index of all oils was decreased considerably, Jatropha oil and the blend being the most reduced. Finally, the anti-shudder property, as measured by the change in the friction coefficient with a sliding speed, of Jatropha oil and automatic transmission fluid was improved by thermo-oxidation at 26 °C but worsened at 100 °C, meanwhile it was barely affected in the blend. Therefore, these results indicate that using pure Jatropha oil as automatic transmission fluid would be unsuitable, but blending it with automatic transmission fluids in specific proportions may be apposite for improving the friction properties of wet clutches even under thermo-oxidative conditions.

Experimental study on the friction stability of paper-based clutches concerning groove patterns

2019 ◽  
Vol 72 (4) ◽  
pp. 541-548 ◽  
Author(s):  
Liang Yu ◽  
Biao Ma ◽  
Man Chen ◽  
He Yan Li ◽  
Jikai Liu
Keyword(s):  
Experimental Study ◽  
Surface Temperature ◽  
Design Methodology ◽  
Automatic Transmission ◽  
Applied Pressure ◽  
Friction Torque ◽  
Content Type ◽  
Rotating Speed ◽  
Wet Clutch ◽  
Transmission Fluid

Purpose This paper aims to study and compare the friction stability of wet paper-based clutches with regard to the radial grooves (RG) and waffle grooves (WG). Design/methodology/approach This paper presents an experimental study of a wet clutch concerning the effect of groove patterns on the friction torque and surface temperature. The friction stabilities of RG and WG are investigated with the applied pressure, rotating speed and automatic transmission fluid (ATF) temperature taken into consideration. Findings The friction torque and surface temperature of WG are larger than those of RG under the same operating condition. The friction torque difference between RG and WG grows with the increase of applied pressure and narrows with the increase of ATF temperature. Additionally, their temperature difference expands via increasing the rotating speed and ATF temperature or reducing the applied pressure; in this way, not only the variable coefficient difference between RG and WG can be narrowed, but also the friction stability of the clutch can be improved dramatically. Originality/value This paper explains the thermodynamic differences between RG and WG; moreover, it is verified experimentally that WG has a better friction stability than RG.

Wet clutch transmission fluid for AWD differentials: base fluid influence on friction characteristics

Tribotest ◽  
10.1002/tt.4 ◽  
2005 ◽  
Vol 12 (1) ◽  
pp. 47-56 ◽  
Author(s):  
Rikard Mäki ◽  
Bager Ganemi ◽  
Richard Olsson
Keyword(s):  
Base Fluid ◽  
Friction Characteristics ◽  
Wet Clutch ◽  
Transmission Fluid

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.

Research on Temperature Rise of Wet Clutch Based on Multi-Field Coupling

2019 ◽  
Author(s):  
Bangzhi Wu ◽  
Datong Qin ◽  
Jianjun Hu ◽  
Qing Zhang
Keyword(s):  
Temperature Field ◽  
Numerical Calculation ◽  
Flow Field ◽  
Field Distribution ◽  
Working Conditions ◽  
Temperature Rise ◽  
Automatic Transmission ◽  
Calculation Model ◽  
Field Coupling ◽  
Wet Clutch

Abstract Wet clutch is widely used in vehicle power transmission, especially in dual clutch automatic transmission. However, due to the unclear understanding of clutch temperature distribution and its influencing factors, the clutch is prone to excessive temperature rise or even wear under severe working conditions or continuous starting conditions. In this paper, the finite element model of stress field distribution of friction pair is established by considering the non-uniform fixed constraint of clamping spring and the non-uniform contact of hydraulic cylinder. Based on the inclined groove structure of the friction plate, the numerical calculation model of the flow field in the groove is established by the finite volume method. On this basis, considering the time-varying characteristics of stress distribution and cooling flow field distribution of clutch friction pairs, a numerical calculation model of clutch temperature field is established, and a multi-field coupling calculation method of clutch is proposed. The distribution of temperature field under different working conditions during clutch engagement is obtained by numerical calculation. The results show that the temperature rise of clutch depends on the target speed of the clutch driving end and the load on the driven end. The research results can provide guidance for the design and control of the clutch.

Sign in / Sign up

Export Citation Format

Share Document