The main objective of active downsizing is to increase the power train efficiency. In order to consistently enhance an approach of active downsizing, it is inevitable to disable and additionally to disengage part of the overall engine displacement volume. The disengagement avoids the friction loss of the piston group as well as its crank- and valve-train section. Therefore, this beneficial approach, the Split-Crankshaft Engine (SCE) is currently under development at the Chair of Internal Combustion Engines in cooperation with the Gear Research Centre (FZG), at the Technical University of Munich. The SCE concept consists of two partial internal combustion engines, which are arranged inline. The Primary Engine (PE) is permanently running while the Secondary Engine (SE) can be switched on and off load-dependently during driving operation. Within the switching process, the electromechanically actuated Split-Clutch Unit (SCU) realizes the run-up of the SE as well as the angular synchronization of both partial engines. Hence, the fuel saving potential of the SCE rests upon raising the load points and additionally saving the whole friction losses of the non-fired cylinders. A detailed full vehicle simulation determines the SCE’s fuel saving potential. All fundamental investigations concerning the whole concepts functionality are based on testing rig and simulative studies. This paper gives a precise description of the mechanical structure of the SCU itself and its mode of operation, followed by the detailed modelling specifications of the whole SCU mechanism. The integration of the Simulink® based SCU’s simulation model into the GT-Suite® based full vehicle simulation via co-simulation is shown subsequently. The SCU’s system performance is discussed according to the results of exclusive preliminary investigations within the full vehicle environment using standardized driving cycles.

Karmann, Stephan Bernhard, Rösler, Sebastian, Wachtmeister, Georg, Fischer, Patrick Daniel, Pflaum, Hermann, Stahl, Karsten

Dynamic Analysis of the Lubrication in a Wet Clutch of a Hydromechanical Variable Transmission

2016-01-80999/27/2016

The paper investigates the oil flow through a multi plate clutch for a hydro-mechanical variable transmission under actual operating conditions. The analysis focuses on the numerical approach for the accurate prediction of the transient behavior of the lubrication in the gear region: the trade-off between prediction capabilities of the numerical model and computational effort is addressed. The numerical simulation includes the full 3D geometry of the clutch and the VOF multi-phase approach is used to calculate the oil distribution in the clutch region under different relative rotating velocities. Furthermore, the lubrication of the friction disks is calculated for different clutch actuation conditions, i.e. not-engaged and engaged positions. The influence of different geometrical features of the clutch lubricating circuit on the oil distribution is also determined. The results show the areas where poor lubrication occurs and extend the experiments where measurements are difficult to carry out. The simulation highlight the regions where high thermal stresses are observed during tests.

Bassi, Andrea, Milani, Massimo, Montorsi, Luca, Terzi, Stefano

Learning Slip Control of an Engine Clutch in a Parallel Hybrid Electric Vehicle for Linear Vehicle Launch

2014-01-17454/1/2014

This work studied the control technique for the engine clutch engagement at launch for the TMED parallel HEV for the improved drivability and dynamic performance. Analysis are done on the speed synchronization of the clutch plates, the speed control using the starter motor (ISG), and the fluid pressure control for the clutch. Possible external factors such as changes in the friction coefficient of transmission fluid, temperature variation, auxiliary power and pressure losses are identified and their effects on the targeted dynamic performance are examined. The targeted system performance was achieved with a learning control technique using fluid pressure as the only control input. This involves the compensation for the effect of external factors on the fluid pressure profile and this effect is memorized for the subsequent slip-launch application. To simulate the dynamics of the drivetrain including the engine clutch at various driving scenarios, a simulation model including the clutch slip dynamics is built. Using the simulation model, the learning factors for the fluid pressure are obtained and its sensitivity on the targeted drivability is analyzed under various driving conditions. By breaking down the error components on the pressure profile, the control compensation points for each of the external factors are found. It is found through the simulations that it requires maximum of two learning iterations to bring the error within the allowable bounds. With analysis on the several external factors, the control method achieved the desired performance with minimum number of learning.

Moon, Seongwook

A Design Guide for Wet Multiple Plate Clutches on Forklift Truck Transmissions Considering Strength Balance between Friction Material and Mating Plate

2013-01-02314/8/2013

Wet multiple plate clutches consist of friction plates, on which a friction material is bonded, and mating plates that are plain metal plates. Since the frequency and the range of load in the field of forklift trucks vary widely and are more severe than those for passenger cars, the wet multiple plate clutches on forklift trucks are often damaged. Damaged clutches that were returned from the field typically had 3 types of symptoms: 1.Only the friction material was damaged, 2.Only the mating plates were deformed, 3.Both symptoms were observed. It was clear that the cause of these symptoms depended on the difference of the operating application and the strength criteria of each part. This showed that a design guide for wet multiple plate clutches considering the strength balance between the two parts according to the work application was required. The relevant flow chart of this design process was proposed.

Okabe, Kazunari, Houjoh, Haruo

SAE No. 2 Friction Test Machine µPVT Test

J2490_201208 (Historical)8/6/2012

Automatic Transmission and Transaxle Committee

Glossary of Terms - Lubricated Friction Systems

J1646_201203 (Current)

3/19/2012

This SAE Recommended Practice defines the principal terms and equations pertaining to automotive automatic transmission clutch plate, band, or other wet-friction systems. The terms apply directly to friction-system testing as is typically conducted on inertia-stop test equipment. Some terms can be directly applied to the analysis of friction in the transmission or brake assembly and other friction-test equipment. The glossary presents terms used to describe the set-up, testing, and results of tests as shown in Figure 1, which were taken on a clutch SAE No. 2 machine. The glossary is intended to provide a collection of definitions in the hope of eliminating confusion in development and their application to passenger cars and trucks. This document focuses on the terminology of friction-system testing. References for this type of testing are shown in Section 2.

Automatic Transmission and Transaxle Committee

Spin Loss Computation for Open Clutch Using CFD

2011-01-12384/12/2011

Open clutch spin loss computation is of interest for new clutch designs. It is desirable to minimize open clutch spin loss. Spin loss in automatic transmission clutches is mainly due to the viscous shear of the transmission fluid. Depending on the relative rotational speed of the plates the spin loss varies. At low rotational speeds the gap between the plates is filled with ATF (Automatic Transmission Fluid) and spin loss increases linearly with the rotational speed. At higher speeds the ATF layer, which is held together primarily by surface tension, begins to breakdown due to higher centrifugal forces and air pockets form at outward radial locations of the clutch plates. This results in a decrease in spin loss for the open clutch. CFD (computational fluid dynamics) modeling is an attractive option in calculating the spin loss for an open clutch. Not only can a CFD model give an accurate estimation of the magnitude and trend of spin loss variation but it can also compare various groove designs. This is a significant advantage compared to some existing analytical methods for spin loss estimation of open clutches, as they are limited to either groove-less designs or designs with radial grooves. This work describes a 3D CFD modeling procedure that yields spin loss computations of sufficiently high accuracy by improvements made to some stated procedures in literature. Effect of variation of design parameters such as number of grooves, flow rates, etc, is studied.

Jammulamadaka, Anand K., Gaokar, Prajal

Proposal of Field Life Design Method for Wet Multiple Plate Clutches of Automatic Transmission on Forklift-trucks

2009-01-293410/6/2009

A method of life calculation for wet multiple-plate clutches has not been established; they are tribological parts and the damage of such parts depends on many intertwining parameters such as operating condition and lubrication condition. The focus of this study is on the clutch plate surface temperature, T, that represents many parameters. A T-N curve was developed for the friction material that is similar to the S-N curve for metal fatigue. Load frequency was measured from actual operating conditions in the field, and from this data the frequency of T was predicted. Field life could then be calculated for wet multiple plate clutches from the aforementioned T-N curve, the field frequency of T, and Miner's law.

Okabe, Kazunari, Fujimoto, Akihiko, Harasawa, Takeshi

Dynamic Analysis of Damper System in Torque Converter

2007-01-37498/5/2007

This paper presents a newly proposed damper system in torque converter to minimize the vibration in powertrain system. The lock-up clutch in torque converter makes engine and transmission connected directly. When the lock-up clutch is engaged, the torque fluctuation of engine is attenuated by the damper system. This function decides the vehicle powertrain dynamic characteristics. To calculate the dynamic characteristics of vehicle, the vehicle model with a six-cylindered diesel engine and eight-speed A/T and three damper systems (conventional damper, turbine damper and new damper system) were structured by using AMESim® that is a commercial S/W. At first, the proposed damper system was analyzed by using the damper spring stiffness of previous damper system. New resonance frequency was appeared around 45Hz which didn't exist in previous damper system. However, this resonance frequency was critical to the dynamic characteristics of the vehicle because engine operation range was between 40Hz and 250Hz. Therefore, this resonance frequency should be excluded from engine operation range. For solving this problem, the stiffness of damper spring was changed by using the stiffness equation proposed by regression analysis. As a result, new resonance frequency could be excluded from engine operation range, and the magnitude of frequency response function of the new damper system was less than that of the previous damper system. The torque and speed fluctuations of the vehicle model with new damper system were also reduced.

Park, Taejun, Song, Jaehoon, Jang, Jaeduk, Joo, Insik

Development of an Electronically-Controlled, Limited-Slip Differential (eLSD) for FWD Applications

2007-01-09254/16/2007

Limited-slip differentials improve traction and handling when compared to open differentials, but offer no active modulation and can compromise typical driving. A number of passive control systems exist that attempt to reduce this compromise. Electronically controlled limited-slip differentials (eLSD) are being introduced that allow active control of the differential in all driving situations and can be operated as an open differential, a fully locked differential, or at any point between these extremes. Such an eLSD system was implemented in two General Motors front wheel drive cars-one on an automatic transmission and applied by the transmission pump, the other on a manual transmission and applied by an external pump. This eLSD system contains a multi-plate wet clutch connected to the differential carrier and right side half-shaft of an all wheel drive capable transmission. It was a bolt-on unit, mounted to the right of the transmission output of a multi-axis transmission, replacing the intermediate shaft. The eLSD system, its implementation, and its effects on traction and handling are detailed. The effects of adding the eLSD system to the demands on the automatic transmission hydraulics and oil management are also discussed.

Ross, Craig S., Carey, Clinton E., Schanz, Todd, Gaffney, Edmund. F., Catalano, Michael

Glossary of Terms - Lubricated Friction Systems

J1646_200608 (Historical)8/25/2006

Automatic Transmission Friction Standards Committee

SAE No.2 Friction Test Machine 6000 r/min Stepped Power Test

J2488_200608 (Historical)8/16/2006

Automatic Transmission Friction Standards Committee

Testing and engineering services

AUTOJUL06_047/1/2006

This special edition of Testing & Simulation focuses on the latest technology for vehicle development and validation. The use of mechatronic systems continues to increase in all types of ground vehicles. From electronic stability control and automated manual transmissions to active dampers and active steering systems, the growing complexity, integration, and need to directly characterize the mechanical, software, and electronic interactions of such systems is creating demand for physical test systems that provide a more efficient means of mechatronics development and validation. By providing engineers with the tools to move mechatronics testing from the proving ground to the test lab, OEMs and suppliers will have a much more precise, safe, affordable, and repeatable means of evaluating component and vehicle performance.

Monaghan, Matthew

DensiForm® Technology for Wrought-Steel-Like Performance of Powder Metal Components

2006-01-03984/3/2006

Power transmission components for automotive applications require high static and dynamic mechanical properties to insure long term system reliability. Historically, high quality wrought steel alloys have been the only materials used in the series manufacturing of high torque transmitting components such as one-way clutch races, transmission gears, sprockets and bearing races. Although powder metal technology offers lower cost components, limitations in static and fatigue properties of sintered materials preclude utilization of conventional powder metallurgy in these applications. To address these shortcomings we have developed DensiForm®, a surface densification technology. Specifically, a densification process is utilized with the net result of a full density layer on critical areas up to 1 mm deep into the part and an overall component density above 92% of the theoretical density. The combination of full density on critical areas, high core density and powder metal alloying flexibility enable the production of sintered components which match the performance of wrought steel in highly stressed applications. Contact and bending fatigue properties are presented along with applications to powertrain components.

Trasorras, Juan R. L., Nigarura, Salvator, Sigl, Lorenz S.

Latest Technique to Improve Driving Surge in CVVT Engine Vehicle

2005-01-23015/16/2005

This paper presents a series of experimental and analytical works to improve driving surge in a vehicle with CVVT (Continuous Variable Valve Timing) engine. To fully understand the surge mechanism, comprehensive vehicle tests were performed in relations to engine pressure variations, rotational dynamics of driveline, and rigid body dynamics of powertrain. Base on such experimental results, a simple yet reliable model was developed and simulated to optimize driveline. This study found that parameters, such as characteristics of the clutch in a torque converter, roll mode of powertrain, and timing of CVVT, were shown to have noticeable influence on performance of driving surge. A significant improvement in surge vibration was possible by optimizing each of these parameters both through simulations and experiments.

Won, Kwang-Min, Chae, Chang-Kook, Seo, Jae-Joon

Limited Slip Wet Clutch Transmission Fluid for AWD Differentials; Part 1: System Requirements and Evaluation Methods

2003-01-19805/19/2003

Part 1 of this paper is focused on requirements and evaluation methods for transmission fluids used to lubricate wet clutches in all-wheel drive systems. Part 2: Fluid Development and Verification; presents more measurement data and shows how these results are used in the fluid development process. The investigated all-wheel drive system, featuring a wet multi-plate clutch with a sintered brass base friction material, is described with emphasis on the demands placed on the transmission fluid. A new test equipment to determine the frictional (μ-V) characteristics of the transmission fluid is described. The equipment can measure the actual temperature experienced by the fluid in the contact zone using an infrared temperature measurement method, as well as temperature in the oil sump and inside the clutch discs by use of thermocouples. Variable operation parameters include velocity, normal force and oil flow.

Mäki, Rikard, Ganemi, Bager, Olsson, Richard, Lundström, Bo

Thermomechanical Effects in a Single-Sided Multidisk Clutch/Brake Design

2002-01-14393/19/2002

In the single-sided design of a multidisk clutch or brake, each disk is composed of a steel core with a single layer of friction material bonded to one side. Each disk in the pack faces in the same direction so that the rubbing surface of friction material slides against the bare metal surface of the adjacent disk. This design has been known for years and can be considered an alternative to the much more common double-sided design. In the paper, thermomechanical effects in the single-sided clutch are studied. Finite element simulation shows characteristic pattern of thermal deformations of friction disks, peculiar to that design. The pattern is accompanied by non-uniform contact pressure at some sliding interfaces and high thermal stresses in the disks. The stresses may exceed the yield limit and this results in the known permanent conical distortions of the disks. The theoretical predictions were confirmed in experimental tests performed on inertia-type test stand. A good agreement in the pattern of thermoelastic deformation and disks' coning was obtained. The major mechanism causing excessive thermal stresses in single-sided design was identified in this study. As a result, the clutch design was modified in order to better accommodate the thermal deformations of the disks. Both the calculations and experimental tests showed that the design improvements significantly reduce maximum temperature, thermal stresses, and thereby the coning problem. This single-sided design was proved to be suitable for high-energy power-shift applications.

Zagrodzki, Przemyslaw, Wagoner, Peter

Fluid for Passenger Car Type Automatic Transmissions

J311_200002 (Historical)

2/22/2000

This SAE Information Report details some of the equipment and procedures used to measure critical characteristics of automatic transmission fluid (ATF) used in current automatic transmissions. It is intended to assist those concerned with the design of transmission components, and with the selection and marketing of automatic transmission fluids for the use in passenger car and light-duty truck automatic transmissions. The information contained herein will be helpful in understanding the terms related to properties, designations, and service applications of automatic transmission fluids.

Fuels and Lubricants TC 3 Driveline and Chassis Lubrication

A Comparison of Methods for Evaluating Automatic Transmission Fluid Effects on Friction Torque Capacity - A Study by the International Lubricant Standardization and Approval Committee (ILSAC) ATF Subcommittee

98267210/19/1998

As part of the International Lubricant Standardization and Approval Committee's (ILSAC) goal of developing a global automatic transmission fluid (ATF) specification, members have been evaluating test methods that are currently used by various automotive manufacturers for qualifying ATF for use in their respective transmissions. This report deals with comparing test methods used for determining torque capacity in friction systems (shifting clutches). Three test methods were compared, the Plate Friction Test from the General Motors DEXRON®-III Specification, the Friction Durability Test from the Ford MERCON® Specification, and the Japanese Automotive Manufacturers Association Friction Test - JASO Method 348-95. Eight different fluids were evaluated. Friction parameters used in the comparison were breakaway friction, dynamic friction torque at midpoint and the end of engagement, and the ratio of end torque to midpoint torque. Correlation among the three test methods was relatively good in the early portions of the test procedures, however as tests progressed correlation deteriorated. A “severity index” was developed that might help explain the deterioration in correlation among the three test methods.

Doi, Jyunichi, Ueda, Fumio, Furumoto, Mitsumasa, Linden, James L., Sprys, Joseph W., Kurashina, Hideo, Hoshikawa, Nobuyoshi, King, Tracey, Murakami, Yasuhiro

Analysis of Temperatures and Stresses in Wet Friction Disks Involving Thermally Induced Changes of Contact Pressure

9820359/14/1998

Thermal distortions of friction disks caused by frictional heating modify pressure distribution on friction surfaces. Pressure distribution, in turn, determines distribution of generated frictional heat. These interdependencies create a complex thermoelastic system that, under some conditions, may become unstable and may lead to severe pressure concentrations with very high local temperature and stress. The phenomenon is responsible for many common thermal failure modes of friction elements and is known as frictionally excited thermoelastic instability (TEI). In the paper, one of the cases of TEI is investigated theoretically and experimentally. The study involves a two-disk structure with one fiction disk and one matching steel disk that have one friction interface. An unsteady heat conduction problem and an elastic contact problem are modeled as axisymmetric ones and are solved using the finite element method. The model allows for investigation of thermally induced changes in contact pressure and accompanying temperature and stress fields. The solutions are calculated for real scenarios of clutch engagement recorded in stand tests. In those tests, transient temperatures at mid-radius of the friction surface are measured using a thermocouple. Also time courses of sliding speed, applied force and torque are recorded. Theoretical solutions show specific behavior of the steel disk in the case when sliding occurs on only one side of the disk, leading to high contact pressure in the central part of the friction surface. These predictions are confirmed by experimental tests, which show temperatures at this location higher than the estimated mean temperature of the surface.

Zagrodzki, Przemyslaw, Farris, Todd D.

Prediction of Torque Response During the Engagement of Wet Friction Clutch

9810972/23/1998

The approximate torque response model for the engagement of a wet friction clutch, developed by Berger [1, 2], was modified and enhanced. The modified Reynolds equation for the film thickness and force balance for the wet clutch pack are solved numerically. The Reynolds equation relates the film hydrodynamic pressure to the film thickness, physical properties of friction materials, and operating parameters. The torque is calculated from the film and asperity pressure distribution at the friction interface. The applied pressure and the interface temperature as a function of time during engagement are considered in the model. The correct average flow factors of Patir and Cheng [3, 4] for ATF flow between rough surfaces are incorporated into the model. The permeability of friction materials and the temperature gradient inside the friction material are considered. The key input parameter for predicting the torque response is the friction coefficient as a function of sliding speed, temperature, and pressure, which can be measured by the Low Velocity Friction Apparatus (LVFA). The effects of physical and operating parameters on the torque response are demonstrated. Finally, the model predictions of the torque response are compared favorably with the experimental measurements under various operating conditions.

Yang, Yubo, Lam, Robert C.

Fundamental Studies on ATF Friction I.

9716215/1/1997

Automatic transmission clutches are complex tribological systems. Frictional performance is controlled by the interaction of base fluids, additive components, composition clutches, and steel reaction plates with varying energy inputs and thermal stresses in an oxidizing environment. This paper, rather than addressing fully formulated fluid performance in such a system, takes a more fundamental approach where the number of system variables is reduced and the relative effects of formulation variables on system performance can be better examined. Relationships among observed friction performance, system oxidation, friction member condition, and representative performance additives are explored using a synthetic base fluid and a conventionally refined mineral base fluid.

Tipton, C. D., Schiferl, E. A.

Slipping Torque Converter Clutch Interface Temperature, Pressure and Torque Measurements Using Inductively Powered Radiotelemetry

9706792/24/1997

Torque converter clutch friction interface and automatic transmission fluid (ATF) temperatures, pressure difference across the clutch piston, flow through the friction material grooves, and engine crankshaft dynamic torque were measured for typical operating conditions on a running transmission. The friction coefficient, clutch unit pressure, fraction of heat rejected to ATF flowing through the grooves, and time dependent thermal response were determined. Simplified heat transfer calculations were compared with thermal data. Clutch interface temperatures were assessed as they relate to the process of friction material and ATF degradation. The inductively powered radiotelemetry system was found to be a robust and powerful tool for investigating continuously slipping clutch system performance.

Throop, M.J., McWatt, D.G.

The Effects of Water on Cellulose-Based Frictional Surfaces in Automatic Transmission Clutch Plates

96191710/1/1996

A bench scale apparatus and accelerated test protocol were developed to evaluate the effect of contamination of automatic transmsission fluid by mg/kg levels of water on cellulose frictional clutch surfaces. The testing indicated that water added at levels as low as 600 mg/kg migrated to the surface of untreated paper frictionals and contributed to loss of the paper coating and erratic torque transfer properties. Treated, “high performance” paper frictional surfaces showed less physical damage but the same torque transfer effects from water contaminated ATF. A mechanism of the water coating, swelling and weakening the hydrophillic cellulose fibers, with subsequent destruction due to hydrodynamic shear was proposed.

Williamson, Will, RhodILLEGIBLE, Blaine

SAE No. 2 Clutch Friction Test Machine Guidelines

J286_199609 (Historical)9/1/1996

Automatic Transmission Friction Standards Committee

Glossary of Terms-Lubricated Friction Systems

J1646_199607 (Historical)7/1/1996

Automatic Transmission and Transaxle Committee

Friction Characteristics of DEXRON®-III Automatic Transmission Fluids

94188710/1/1994

The friction characteristics of several DEXRON®-III automatic transmission fluids were examined in a variety of friction tests. These evaluations included tests with SAE No. 2 Friction Machines using either Band or Plate heads, breakaway friction tests, and low-sliding speed friction tests. The effect of bulk fluid temperature on friction performance was examined in band tests and in breakaway tests using the plate clutch apparatus. The DEXRON®-III fluids were compared to the previous generation automatic transmission fluids. Results showed that the DEXRON®-III fluids exhibited more desirable friction characteristics; for example, with the DEXRON®-III fluids in the band machine, dynamic friction remained stable during sustained operation at high temperature, whereas with DEXRON®-IIE fluids, dynamic friction decreased as much as 25%. Band tests and breakaway friction tests at various temperatures showed fluid friction characteristics and durability to be sensitive to bulk fluid temperature, but with the DEXRON®-III fluid being less sensitive than the DEXRON®-IIE fluid.

Linden, James L., Stebar, Russell F., Kemp, Steven P.

Tracking Wet Friction Performance Via Energy Dispersive X-Ray Spectroscopy

9410333/1/1994

This paper describes a technique which uses Energy Dispersive X-ray Spectroscopy (EDX) to track progressive changes in wet friction material surface chemistry as the material is cycled under various energy and temperature conditions. Using this technique, elements can be identified on the surface and compared with the base friction material and fluid chemistries to obtain a quantitative measure of chemistry changes at the interface. Performance effect of surface chemistry change can be obtained by corresponding measurement of the coefficient of friction. Additionally, surface chemistry changes can be compared with progressive changes in friction material degradation as measured by Thermogravimetric Analysis (TGA) after identical conditions of use. Surface chemistry change and mating surface temperatures have been measured versus cycles at several energy loadings. Separate tests have been performed to follow friction material degradation changes during cycling. The results show that performance correlates closely with surface chemistry changes that occur dependant on surface temperature/time conditions produced by the energy/power loadings of the application. Friction material degradation is an separate mode of change which is also dependant on the energy/power loadings of the application. The EDX technique provides a method of distinguishing between these changes, leading to a better understanding of failure modes and the energy/power, time/temperature conditions under which these modes occur.

Fish, Robert L., Truncone, Samuel A.

Intricacies of SAE #2 Computerized Clutch Friction Durability Testing

93284710/1/1993

This paper discusses the implications of computerizing the SAE #2 clutch friction durability tests that General Motors Corporation and Ford Motor Company require for automatic transmission fluid certification. There are three reasons for this paper. 1) Friction durability testing is a significant part of a much larger battery of tests needed to qualify a fluid. 2)There have been recent modifications concerning computerization of both the Ford and GM tests. 3) Because there are only two OEM qualified testing facilities, the details of certain testing intricacies in the areas of data acquisition, reduction and reporting may not be as understood as well as in other areas of automotive-based standardized testing. Formulators of automatic transmission fluid need to be aware of all details surrounding the collection and evaluation of the data that will result in the final test report. This paper focuses on the algorithms and nuances of data acquisition, data reduction, and report generation as based on the issued test specifications by Ford and GM. The intention of this paper is to give insight into the computerization and reporting aspects; it is not to interpret or restate the issued specifications. It is hoped that the various automatic transmission fluid (ATF) formulators will find this paper of significant interest, for they are the intended audience.

Marty, Steve, Carpenter, Bill

The Effect of Separator Flatness on the Performance and Durability of Wet Friction Clutches

9309153/1/1993

The automatic transmission clutch represents a complex system involving critical interactions between the separator plates, fluid, operating conditions and friction material. This paper focuses on the effect of separator plate flatness on the performance and durability of two friction materials on an SAE #2 machine. The data from this study shows that flat separator plates yield higher dynamic coefficients and lower wear when compared to non-flat plates. These effects were obtained for separator plates with peak-to-peak departure from flatness values between approximately .08mm and .25mm. In addition, other variables such as material elastic modulus, separator plate thickness, and material operating pressure were studied. The use of soft friction materials to improve performance with non-flat reaction plates was quantified.

Barker, Keith

Thermal and Mechanical Damage of Paper Wet Friction Material Induced by Non-Uniform Contact

9220959/1/1992

Black mottled patterns often apear on the surfaces of steel reaction plates in wet paper friction clutch system. This phenomenon results from non-uniform contact in the clutch pack. It isexperientially said that this non-uniform contact in the wet paper friction clutch shortens its life. To date the damage by non-uniform contact has not been studied quantitatively. Analysis of this phenomenon was studied to determine its relationship to the life of the wet friction system's frictional and durability characteristics. By analyzing the relationship between friction surface temperature, degree of non-uniform contact of the clutch pack and the degree of damage on the friction materials (or the whole clutch pack system), useful information for actual clutch and brake application has been obtained.

Takezaki, Kenichi, Kubota, Masamitsu

A New Method to Calculate Energy Dissipation and Temperature Distribution in Multidisc Clutches in Powershift Transmissions

9118829/1/1991

This paper describes a simulation program to calculate energy throughput and temperature distribution in a clutch pack in powershift transmissions for any gear change. Unlike other approaches, the program is built as a time related loop in which both mechanical and thermal variables are calculated. This approach permits a flexible implementation of dependencies of all variables on each other. Given an applied clutch pressure of any shape, the behaviour of any powershift transmission configuration can be calculated. Special care has been taken to solve the temperature equation, using an implicit notation and a technique called TriDiagonal Matrix Algorithm.

Wouters, Marc

Using the SAE #2 Machine to Evaluate Wet Clutch Drag Losses

910803

2/1/1991

The study of energy losses in disengaged wet clutches is important to efforts to maximize the efficiency of automatic transmissions. This paper describes a simple, accurate method of investigating clutch drag using the SAE #2 machine. By recording coast down speed versus time with known inertia, average and instantaneous torques can be calculated. Bearing and component losses can also be identified by running empty and partially built clutches. Many individual variables can be studied under laboratory controlled conditions. Friction plate geometry, surface finish, groove design, and plate flatness are evaluated at various levels of pack clearance, oil flow, oil level, and temperature. The influence of clutch speed on the magnitude of power loss is also shown. Results are analyzed to demonstrate the relative contribution of each factor. Conclusions are drawn to maximize effectiveness of effort to reduce power loss.

Fish, Robert L.