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SAE No. 2 Friction Test Machine µPVT TestJ2490_202511 (Current)11/25/2025
This SAE Recommended Practice is intended as the definition of a standard test, which may be subject to frequent change to keep pace with experience and technical advances. This should be kept in mind when considering its use.The SAE No. 2 Friction Test Machine is used to evaluate the friction characteristics of automatic transmission plate clutches with automotive transmission fluids. It can also be used to conduct durability tests on wet friction systems.The specific purpose of this document is to define a µPVT Test for the evaluation of the variation of wet friction system performance as a function of speed, temperature, and pressure. This procedure is intended as a standard for both suppliers and end users.The only variables selected by the supplier or user of the friction system are:a. Friction materialb. Fluidc. Reaction platesThese three variables must be clearly identified when reporting the results of this test. If any of the test parameters or system hardware as described in this document are changed, other than the friction material, test fluid, or reaction plates, the data may not be reported as having been obtained using this document.This procedure is intended to evaluate the endpoint/midpoint ratios, midpoint and breakaway coefficients. The procedure can be used to demonstrate changes that occur between the different levels of engagement speed, sump temperature, and apply pressure. Refer to SAE J2487, SAE J2488, or SAE J2489 for coefficient variations due to changes in power level.The procedure, as described in detail in Table 1, consists of four 50 cycle break-in levels at 3500 rpm with increasing steps of apply pressure, followed by 16 levels consisting of 25 dynamic engagements, and one breakaway following completion of the 25th dynamic cycle. The 16 levels are achieved by varying initial engagement speed, apply pressure, and oil sump temperature while the inertia is kept constant at 0.701 kg/m2.
Automatic Transmission and Transaxle Committee
SAE No. 2 Friction Test Machine 6000 rpm Stepped Power TestJ2488_202511 (Current)11/25/2025
This SAE Recommended Practice is intended as the definition of a standard test, but may be subject to frequent change to keep pace with experience and technical advances. This should be kept in mind when considering its use.The SAE No. 2 Friction Test Machine is used to evaluate the friction characteristics of automatic transmission plate clutches with automotive transmission fluids. It can also be used to conduct durability tests on wet friction systems.The specific purpose of this document is to define a 6000 rpm stepped power test for the evaluation of wet friction system performance variation as a function of power level. This procedure uses an initial engagement speed of 6000 rpm and is intended as a standard procedure for common use by both suppliers and end users.The only variables selected by the supplier or user of the friction system are:a. Friction materialb. Fluidc. Reaction platesThese three variables must be clearly identified when reporting the results of using this test. If any of the test parameters or system hardware as described in this document are changed, other than the friction material, test fluid, or reaction plates, the data may not be reported as having been obtained using this document.This procedure is not intended to evaluate the initial coefficient or break-in characteristics. For this information, refer to SAE J2490 SAE No. 2 Friction Test Machine PVT test.
Automatic Transmission and Transaxle Committee
SAE No. 2 Friction Test Machine 3600 rpm Stepped Power TestJ2487_202511 (Current)11/21/2025
This SAE Recommended Practice is intended as the definition of a standard test, but may be subject to frequent change to keep pace with experience and technical advances. This should be kept in mind when considering its use.The SAE No. 2 Friction Test Machine is used to evaluate the friction characteristics of automatic transmission plate clutches with automotive transmission fluids. It can also be used to conduct durability tests on wet friction systems.The specific purpose of this document is to define a 3600 rpm Stepped Power Test for the evaluation of wet friction system performance variation as a function of power level. This procedure uses an initial engagement speed of 3600 rpm and is intended as a standard procedure for common use by both suppliers and end users.The only variables selected by the supplier or user of the friction system are:a. Friction Materialb. Fluidc. Reaction PlatesThese three variables must be clearly identified when reporting the results of using this test. If any of the test parameters or system hardware as described in this document are changed, other than the friction material, test fluid, or reaction plates, the data may not be reported as having been obtained using this document.This procedure is not intended to evaluate the initial coefficient or break-in characteristics. For this information, refer to SAE J2490.
Automatic Transmission and Transaxle Committee
Automatic Transmission Intake Filter Test ProcedureJ2312_202106 (Current)6/22/2021
This test procedure is intended to apply to hydraulic pump suction filters and strainers used in automotive automatic transmissions that include hydraulic power pumps. The various paragraphs of Section 5 include a variety of tests and alternative tests that are not applicable to all filters and applications, so the engineer must specify which tests are to be performed for a particular application. These test procedures are intended to evaluate filter functional performance characteristics only, durability is not evaluated under this standard. Filter design requirements must be specified by the engineer on the filter assembly drawing, an applicable engineering specification, or summarized on an application data sheet similar to that found in this recommended practice. See Figure 6. Pressure circuit filters, both barrier and system contamination control types, are not covered under this standard. They are similar in design and construction to filters used in many hydraulic and lubricating applications. Testing for pressure filters are covered by the ISO and SAE standards listed under references in Section 2.
Automatic Transmission and Transaxle Committee
Transmission Oil Cooler HoseJ1532_202106 (Current)6/10/2021
This SAE Standard covers hose intended for use with automatic transmission cooling system applications. Type A hoses are intended for original equipment or replacement applications while Type B hoses are intended for aftermarket auxiliary cooler applications only. The reference fluid for tests requiring the use of automatic transmission fluid (ATF) shall be Dexron III / Mercon 5 or equivalent ATF that is agreed to by hose manufacturer and customer.
Non-Hydraulic Hose Committee
PERFORMANCE SPECIFICATION FOR AUTOMOTIVE WIRE HARNESS RETAINER CLIPSUSCAR44-1 (Historical)1/20/2021
This specification describes a method and acceptance criteria for testing automotive wire harness retainer clips. Retainer clips are plastic parts that hold a wire harness or electrical connector in a specific position. Typical plastic retainers work by having a set of “branches” that can be inserted into a hole sized to be easy to install but provide acceptable retention. This specification tests retainer clips for mechanical retention when exposed to the mechanical and environmental stresses typically found in automotive applications over a 15-year service life. This specification has several test options to allow the test to match to the expected service conditions. The variability of applications typically arises from different ambient temperatures near the clip, different proximity to automotive fluids, different exposure to standing water or water spray, and different thicknesses of the holes that the clip is inserted into. Clips are typically inserted into sheet or rolled metal from 0.6 to 8 mm thick, so this specification focuses on that range. Outside of this range requires a custom test. The procedures described in this document have been evaluated for the design types shown in Table 2. Use of USCAR-44 for other than a design shown in Table 2 may or may not produce acceptable test correlation to actual experience, but USCAR has not reviewed any data. USCAR-44 can be used at all phases of development, production, and field analysis since it is a performance test and not a process validation or quality assessment. No retainer may be represented as having met USCAR/EWCAP specifications unless conformance to all applicable requirements of this specification have been verified and documented. All required verification and documentation must be provided by the supplier of the part. If testing is performed by another source, it does not relieve the primary supplier of responsibility for documentation (DVP&R) of all test results and for verification that all samples tested met all applicable acceptance criteria.
USCAR
Characterization and Modeling of Wet Clutch Actuator for High-Fidelity Propulsion System Simulations2020-01-14144/14/2020
Innovations in mobility are built upon a management of complex interactions between sub-systems and components. A need for CAE tools that are capable of system simulations is well recognized, as evidenced by a growing number of commercial packages. However impressive they are, the predictability of such simulations still rests on the representation of the base components. Among them, a wet clutch actuator continues to play a critical role in the next generation propulsion systems. It converts hydraulic pressure to mechanical force to control torque transmitted through a clutch pack. The actuator is typically modeled as a hydraulic piston opposed by a mechanical spring. Because the piston slides over a seal, some models have a framework to account for seal friction. However, there are few contributions to the literature that describe the effects of seals on clutch actuator behaviors. In a routine simulation, a spring constant is commonly tuned to match vehicle data, assuming that it captures the effects of seal friction. The validity of this approach is not well established. This article describes the characterization and empirical modeling of a wet clutch actuator. The effect of seal friction is examined in detail during stroking and de-stroking. It is found that the seal friction is highly non-linear and directional. It introduces a significant error in clutch applied force calculation unless seal friction is explicitly accounted for. Propulsion system simulations are conducted to demonstrate the significant impact of seal friction on clutch operation and the quality of simulations. A framework of a new actuator model is proposed to represent seal friction based on empirical observations of its complex behaviors.
Haria, Hiral, McCallum, James, Fujii, Yuji, Tsuchiya, Takahiro, Miyagawa, Masatoshi, Nakamura, Shinji, Wendel, Matthew, Katopodes, Nikolaos
Studying Ignition Delay Time of Lubricant Oil Mixed with Alcohols, Water and Toluene in IQT and CVCC2020-01-14224/14/2020
The auto-ignition of liquid fuel and lubricant oil droplets is considered as one of the possible sources of pre-ignition. Researchers are continually finding new ways to form advanced lubricant oil by changing its composition and varying different oil additives to prevent the occurrence of this event. This study investigates additives for lubricants to suppress its auto-ignition tendency. Three sets of mixtures were prepared. The first set of mixtures were prepared by adding different alcohols namely ethanol, and methanol to the commercial lubricant oil (SAE 15W-40) in ratio of 1 - 5 % by vol The second set of mixtures were prepared by mixing SAE 15W-40 with aforementioned alcohols (1 % vol.) and H2O (1 % vol.). Lastly, the third set of mixtures were prepared by adding toluene to SAE 15W-40 in (1 % - 5% by vol.). Two experimental setups were used in the current work. An Ignition Quality Tester (IQT) was used to investigate the mixtures’ ignition delay time (IDT) following standard ASTM D6890 procedure, and a larger constant volume combustion chamber (CVCC) was used to investigate the combustion characteristics of a suspended single oil droplet. In the CVCC chamber, the droplet was ignited in an atmosphere of air at 300 °C and pressure ranging from 4 bar - 22 bar at 6 bar interval pressures. IDT of lubricant oil was considered as the base IDT, which was compared to those of other mixtures. Addition of alcohols and water in lubricant oil showed a significant increase in IDT compared to toluene addition. On the contrary, the addition of toluene resulted in a decrease in IDT. Among the alcohols, methanol addition showed higher IDT than ethanol addition. Alcohols increased the IDT effectively only beyond the addition of > 4 % by vol.
Maharjan, Sumit, Elbaz, Ayman, Mitsudharmadi, Hatsari, Roberts, William
Prediction of Friction Durability in Off-Road Applications Based on Mechanistic Understanding of the Effects of Fluids and Surfaces on Clutch Friction2019-01-233912/19/2019
After new transmission lubricants are developed there is an extensive validation program where friction durability testing is performed on multiple clutch materials. Each durability test can run for long terms and the entire validation program can take much longer terms. A well designed lubricant and friction material will deliver the necessary friction control for construction equipment to operate at optimum level. A mechanistic construct has been evaluated to calculate friction durability in clutch systems based on fluid and surface tribological properties. Fluid properties include both boundary frictional and rheological effects. Surface properties include elastic modulus, surface roughness, asperity density and asperity tip radius. Using this mechanistic construct friction durability has been predicted. In the past, researchers in the field have often associated lubricant induced glazing of the friction material surface as the cause of the loss of friction control in clutch systems. In the current study, results show that wear is also a dominant cause of friction loss. In short clutch friction tests the rate of change in surface properties and fluid properties have been determined. Fluid friction properties do not change in these tests and surface properties of materials can change significantly. Based on the rate of change in surface properties, friction durability predictions have been made in order to shorten product validation time.
Devlin, Mark, Adhvaryu, Atanu, Cameron, Timothy, Kariwa, Shinpei, Abekawa, Toshiharu
Understanding Base Oils and Lubricants for Electric Drivetrain Applications2019-01-233712/19/2019
ABSTRACT The penetration of hybridization and electrification (HEV and EV) technology into automotive powertrain designs is an evolving trend resulting from global regulations intended to reduce transportation-related emissions of greenhouse gases and other pollutants and to improve vehicle fuel efficiency. In many HEV and EV hardware designs, drivetrain fluids have contact with the integrated electric motor (e-motor), which requires electrical and thermal properties to be considered in addition to traditional fluid properties. This paper discusses new insights gained around electrical and thermal properties of drivetrain fluids, with a specific emphasis on understanding the critical impacts of base oils (BOs). Electrical and thermal properties data as a function of temperature for a range of BOs as well as automatic transmission fluids are shared. We found that BOs and their viscosities play a critical role in cooling performance, while additives play a critical role in electrical conductivity (EC). That being said, we also have observed that additives in BOs can modify cooling performance. We will demonstrate how each component in the additive package affects EC and in some cases cooling performance. The successful utilization of this knowledge is demonstrated on a proof-of-principle basis to show that fluids with appropriate electrical and thermal properties can be designed to meet critical factors for electrification such as cooling capacity and EC, while still maintaining essential performance features for conventional driveline fluids.
Kwak, Yungwan, Cleveland, Christopher, Adhvaryu, Atanu, Fang, Xinggao, Hurley, Susie, Adachi, Tsuneo
Development of Motor Cooling Technology in Hybrid Vehicles2019-01-231212/19/2019
1 In order to reduce the size and weight of the hybrid motor, improving motor cooling performance is essential. Therefore, we have been working on the development. This paper will explain the development of cooling technology TOYOTA has been working on, specifically the evolution of the hybrid motor cooling system and structure from the 1st generation Prius to the current model.
Matsumoto, Takashi, Kato, Hiroki, Takizawa, Keiji, Yashiro, Takahisa, Okazaki, Sho, Tabuchi, Kenta
Ford ‘cranks’ it up with another big V8 for Mustang19AUTP09_119/1/2019
When Ford introduced the Mustang Shelby GT350 in 2015, it was the pinnacle of Mustang-ness thanks to its 5.2-L DOHC “Voodoo” V8 that featured a flat-plane crankshaft design to enable sky-high revs (the GT350's 8200-rpm redline is one reason Ferrari has long specified flat-plane V8s) and a rollicking 526 hp at 7,500. Then there's the exotic “rip” exhaust note unique to flat-plane V8s. But contemporary musclecar development times seemingly are as quick as their ever-dropping 0-to-60 mph runs-and before Ford released the Shelby GT350, its SAE-certified 526 hp already had been eclipsed by the 707-hp supercharged 6.2-L Hemi V8 in the Dodge Challenger SRT Hellcat and later the 797-hp Hellcat Redeye. Prior to all this, GM's Chevrolet started the hyper-power frenzy by generating 650 hp from the supercharged 6.2-L OHV V8 launched for the 2012 Camaro ZL1.
Visnic, Bill
Torque and Pressure CFD Correlation of a Torque Converter06-12-03-00128/22/2019
A torque converter was instrumented with 29 pressure transducers inside five cavities under study (impeller, turbine, stator, clutch cavity between the pressure plate and the turbine shell). A computer model was created to establish correlation with measured torque and pressure. Torque errors between test and simulation were within 5% and K-Factor and torque ratio errors within 2%. Turbulence intensity on the computer model was used to simulate test conditions representing transmission low and high line pressure settings. When turbulence intensity was set to 5%, pressure simulation root mean square errors were within 11%-15% for the high line pressure setting and up to 34% for low line pressure setting. When turbulence intensity was increased to 50% for the low line pressure settings, a 6% reduced root mean square error in the pressure simulations was seen. For all pressure settings, cavities closer to the converter inlet required a 5% turbulence intensity while the cavities inside or near the torus were better suited with 50% turbulence intensity levels.
De Jesus Rivera, Edward, Woodland, Mark, Robinette, Darrell, Blough, Jason, Anderson, Carl, Frait, Steve, Devendran, Ram
Testing Methods and Signal Processing Strategies for Automatic Transmission Transient Multiplexed Pressure Data2019-01-15006/5/2019
Transmissions have multiple transient events that occur from gear shifting to torque converter clutch application. These transients can be difficult to capture and observe. A six speed front wheeled drive transmission was instrumented with pressure transducers to measure clutches and the torque converter. Due to size restrictions internal to the torque converter the data had to be multiplexed across three different transmitters. A method to capture a transient event through the use of multiplexed data was developed to create a data set with the transient event occurring on each channel. Once testing is completed, the data has to be split into individual channels and synced with the operational data. The data then can be used in both time and frequency domain analysis. It is important to understand that the data is not continuous and must be taken into consideration when post processing it for further results.
Woodland, Mark, Blough, Jason, Robinette, Darrell, Anderson, Carl, Frait, Steve, Devendran, Ram Sudarsan
Development of Electric Oil Pump Controller in Hybrid Vehicle Based on PMSM (Permanent Magnet Synchronous Motor) and the AUTOSAR Platform2019-01-07654/2/2019
Traditional hybrid vehicles operated two types of oil pump, mechanical for combustion engine and electrical for electric motor, to supply oil pressure for automatic transmission in each power source. New hybrid vehicles has only one electrical pump to reduce system volume and to improve fuel efficiency. Purposes of this study are to make standardization of firmware development process for oil pump unit (OPU) and electric oil pump (EOP) and to apply permanent magnet synchronous motor (PMSM) instead of brushless DC (BLDC) motor. In old-fashioned non-operating system (OS) firmware, it was convenient to calculate control timing for motor control, however the firmware was deeply dependent to specific microcontroller Unit (MCU). In other words, much of efforts and time are needed if new MCU were applied. In this study, new standard development process for MCU firmware can be built up based on automotive open system architecture (AUTOSAR) platform by developing specific motor complex device driver (CDD). In existing system, the OPU supplied with high-voltage from battery drives the BLDC motor driven with six-step block commutation method through the hall sensor inputs. In new system of this study, sensorless vector control algorithm for PMSM is applied to improve motor performance and sensorless algorithm helps to reduce failure risk caused by position sensor.
Kim, Haejin, Ryu, Seung-yun, Yoo, Hojeong, Kim, Hyoungsu, Kim, Gyeongcheol
CVT Ratio Scheduling Optimization with Consideration of Engine and Transmission Efficiency2019-01-07734/2/2019
This paper proposes a transmission ratio scheduling and control methodology for a vehicle with a Continuous Variable Transmission (CVT) and a downsized gasoline engine. The methodology is designed to deliver the optimal vehicle fuel economy within drivability and performance constraints. Traditionally, the Optimum Operating Line (OOL) generated from an engine brake specific fuel consumption map is considered to be the best option for ratio scheduling, as it defines the points at which engine efficiency is maximized. But the OOL does not consider transmission efficiency, which may be a source of significant losses. To develop a CVT ratio schedule that offers the best fuel economy for the complete powertrain, an empirical approach was used to minimize fuel consumption by considering engine efficiency, CVT efficiency, and requested vehicle power. A backward-looking model was used to simulate a standard driving cycle (FTP-75) and develop a new powertrain-optimal operating line (P-OOL). Simulation results using the backward-looking model show a significant improvement in overall fuel economy when using the P-OOL (considers engine and CVT efficiency) compared to the OOL (considers only engine efficiency). Next, a forward-looking, velocity-driven model was developed to simulate the real-time behavior of a vehicle. Fuel economy results were compared when implementing the P-OOL and the OOL with a hardware-based CVT shift rate constraint. Finally, a control algorithm that considers powertrain loss and inertia torque due to CVT ratio changes is proposed to minimize powertrain response lag when operating along the P-OOL. This combined ratio scheduling and response lag control methodology is shown to improve vehicle fuel economy with real-time simulated driving conditions.
Deshmukh, Paresh, Beuerle, Steven, Hudson, Jennifer, Chen, Weitian, Dai, Edward, Hu, Guopeng, Xu, Yang
Development of Motor with Heavy Rare Earth-Free Magnet for Two-Motor Hybrid System2019-01-06004/2/2019
Conventional HEV motors use neodymium magnets with added heavy rare earths, to realize high output and size reduction. However, deposits of heavy rare earths such as Dysprosium (Dy) and Terbium (Tb) are unevenly distributed, so it is important to reduce the amount used, because of supply issue and material cost. In this paper, the application of a heavy rare earth-free magnet is considered on the new motor for a two-motor hybrid system. Compared to conventional neodymium magnets, heavy rare earth free magnets tend to have low coercivity. Also, heavy rare earth-free magnet have low thermal durability, so it is not easy to apply them to motors for a two-motor hybrid system, which requires high output and small size. The motor requires twice as much torque and six times output than one-motor hybrid system. Increase demagnetization resistance and magnet cooling performance is studied by development of the new motor. With the new rotor structure, a magnetic circuit suitable for the magnetic property of heavy rare earth-free magnet was designed, and demagnetization resistance property is raised 24%. Also, the new motor cooling system is a shaft cooling structure, which uses centrifugal force to supply refrigerant to the interior of the rotor yoke, achieving a 23% increase in magnet cooling performance. This technology succeeded in applying heavy rare earth-free magnet to the motor for a two-motor hybrid system, while maintaining high power density.
Ito, Yuta, Aoki, Tadanobu, Naito, Tomokazu, Hiranishi, Toru
Modeling, Control, and Adaptation for Shift Quality Control of Automatic Transmissions2019-01-11294/2/2019
The parameters determining shift quality control in automatic transmissions are determined as part of the calibration of the transmission control. The resulting control system typically has three components: feedforward control, where the control output is determined before a gearshift; feedback control, where the control output is determined during the gearshift based on sensed feedback; and learning control (adaptation), where the feedforward or feedback controller parameters are modified after the current gearshift has ended and before the next similar gearshift begins. Gearshifts involving the same ratio change are referred to here as similar gearshifts, though such gearshifts may involve differences in other variables such as vehicle speed or engine torque. In most automatic transmissions, gearshifts are controlled by hydraulic clutches, and operating conditions for these clutches may vary widely, requiring a dedicated transmission controller involving significant calibration effort. In the current work, novel model-based methods are used to accomplish feedforward control of gearshifts, involving offline calibration of fill and torque phase control parameters and learning control of the fill phase. Towards this end, a physics-based model of the oncoming clutch involved in an upshift of a production automatic transmission was developed and experimentally validated against test bench experiments for a wide variety of inputs and operating conditions. The resulting model is used to generate a feedforward controller, offline model-based calibration algorithm, and a learning controller that corrects for clutch under-fill and over-fill. The effectiveness of the resulting controller is validated by simulation studies using the experimentally validated transmission hydraulic system model, in conjunction with a powertrain model. In particular, it is demonstrated that the learning controller corrects for initial under- or over-fill error in two to three gearshifts. Convergence and robustness properties, and transient performance of the learning controller are also discussed.
Mishra, Kirti Deo, Cardwell, Gilbert, Srinivasan, Krishnaswamy
Application of Empirical Asperity Contact Model to High Fidelity Wet Clutch System Simulations2019-01-13014/2/2019
Wet clutches are complex hydrodynamic devices used in both conventional and electrified drivetrain systems. They couple or de-couple powertrain components for applications such as automatic shifting, engine disconnect and torque vectoring. Clutch engagement behaviors vary greatly, depending on design parameters and operating conditions. Because of their direct impact on vehicle drivability and fuel economy, a predictive CAE model is desired for enabling analytical design verification processes. During engagement, a wet clutch transmits torque through viscous shear and asperity contact. A conventional Coulomb’s model, which is routinely utilized in shift simulations, is inadequate to capture non-linear hydrodynamic effects for higher fidelity analysis. Extensive research has been conducted over the years to derive hydrodynamic torque transfer models based on 1D squeeze film or 3D CFD. They are typically coupled with an elastic asperity contact model for mechanical torque transfer. However, the recent advancement reveals no significant asperity deformation at the frictional surface during engagement and establishes a new empirical asperity contact model. This paper describes the integration of the empirical asperity contact model with CFD for developing a high-fidelity wet clutch engagement model. The asperity models are examined in detail for four friction materials to highlight distinct contact behaviors. They are coupled with 3D CFD model in OpenFOAM for engagement simulations, demonstrating the importance of selecting the right asperity model for predictive clutch analysis. A breakdown of hydrodynamic and mechanical torques is provided, enabling numerical examination of clutch engagement processes. Simulation results are compared with clutch module test data that is specifically designed to replicate actual shifting conditions. It is found that accurate simulation of a complete clutch system requires not only engagement physics, but also in-depth understanding of actuator characteristics such as seal drag.
Haria, Hiral, Fujii, Yuji, Pietron, Gregory M., Wang, Pengchuan, Katopodes, Nikolaos, Miyagawa, Masatoshi, Tsuchiya, Takahiro, Nakamura, Shinji, Wendel, Matthew, Miyoshi, Hiroya
Efficiency Evaluation of Lower Viscosity ATF in a Planetary Automatic Transmission for Improved Fuel Economy2019-01-12964/2/2019
With continued industry focus on reducing parasitic transmission and driveline losses, detailed studies are required to quantify potential enablers to improve vehicle fuel economy. Investigations were undertaken to understand the influence of lower viscosity Automatic Transmission Fluids (ATF) on transmission efficiency as compared with conventional fluids. The objectives of this study were to quantify the losses of lower viscosity ATF as compared with conventional ATF, and to understand the influence of ATF properties including viscosities, base oil types, and additive packages on fuel efficiency. The transmission efficiency investigations were conducted on a test bench following a vehicle-based break-in of the transmission using a prescribed drive cycle on a chassis dynamometer. At low temperature, the lower viscosity ATF showed a clear advantage over the conventional ATF in both spin loss and loaded efficiency evaluations. At high temperature, mixed results were obtained; it appeared the chemistry of ATF influenced the results. Overall, using the low viscosity fluid tends to improve loss behavior, but the benefits can be offset if the transmission hardware employed is not specifically designed for low viscosity fluids. Potential noise factors of the test method were discussed along with the strategies to reduce them which included oil flushing method, break-in method, and selection of test transmission design. This project was undertaken and financially supported by the Transmission Working Group (TWG) of the United States Council of Automotive Research (USCAR).
Tang, Haiying, Zreik, Khaled, Ohtani, Hiroko, D'Anna, Thomas, Murtagh, Jason E., Wellmann, Thomas
Automotive Gear Lubricant Viscosity ClassificationJ306_201902 (Current)2/6/2019
This SAE Standard defines the limits for a classification of automotive gear lubricants in rheological terms only. Other lubricant characteristics are not considered.
Fuels and Lubricants TC 3 Driveline and Chassis Lubrication
Ricardo reveals details of latest e-motor and eDCT19AUTP02_122/1/2019
United-Kingdom engineering specialist Ricardo recently revealed extensive development details of its latest automotive 48-V 25-kW e-motor and associated inverter, which it claims can deliver up to a 50% increase in power density compared with current production electric machines. The project is of potential significance to automotive OEMs moving towards high-volume electric-vehicle (EV) production models requiring enhanced motor power density without cost and complexity drawbacks. Emphasis during the new e-motor's development was placed on thermal management-chiefly, gaining efficiency via reduction of thermal resistance, particularly concerning the inverter's metal oxide semiconductor field-effect transistor (MOSFET). Ricardo revealed its solution is based on the use of direct oil cooling of the heat sink, using the same automatic transmission fluid used to cool the emotor itself.
Birch, Stuart
Gearset Synchronization Modeling of a Heavy Commercial Vehicle Transmission and Correlation with Objective Measurements of Gear Shift Quality2019-01-00311/15/2019
For manual transmissions, including the automated types, reduced shifting effort and easy of gear set engagements in a short period of time without rattles and shakes are major requirements for the shift quality evaluations. Performance of the synchronizer mechanisms depends highly on the design, material and arrangement of the transmission synchronization components; thus, the synchronization process is a mechanical and tribological process which is influenced by numerous design parameters of the synchronizers, constraints and properties of the lubricated contacts. In this study, a detailed multi-body-dynamics model for a HCV (Heavy Commercial Vehicle) transmission gearset is presented; various synchronization simulations are performed and the results are compared with the objective shift quality measurements. The developed model yields total synchronization and engagement time based on the applied gear shifting effort. The translational and rotational movements are calculated using the force and moment balance in each stage of the synchronization process solving the governing differential equations numerically. Synchronizer mechanisms are frictional lock-up mechanisms that the synchronization process needs to be considered and evaluated step by step due to the transient nature of lubrication regimes from hydrodynamic to boundary as a result of changing lubricant film thickness, oil viscosity and kinetic coefficient of friction. Besides, the transmission shifting system has complex linkages and detents that is included in the model because of their significant influence on the shift quality. The developed gear set synchronization model was validated using objective GSQA (Gear Shift Quality) measurements obtained in real heavy duty commercial vehicle field tests and various shifting scenarios were simulated. The effects of principal synchronizer design parameters and level of applied force on the shift quality characteristics were discussed in detail.
Özpınar, İlker, Akalin, Ozgen
Development of Hose and Pipe Assembly for Automatic Transmission Cooling System2019-26-03271/9/2019
Rubber hose and metallic pipe with crimped joints are extensively used in steering system assembly, transmission oil cooler system, brake system etc. to carry hydraulic fluid or lubricants from one place to another. The pipe and rubber hose assembly provides necessary flexibility for complex routing on the vehicle level. Design of hose and pipe assembly for this application are different due to difference in operating pressure and temperature requirement for vehicle application. This paper defines the criteria for design and validation of hose & pipe assembly used to connect automatic transmission with the cooler. Crimped joints are validated for their separation force, leakages, ability to withstand pressure pulsations, burst test etc. Parameters which influence the hose & pipe assembly durability are pipe end flaring dimensions, type of crimping, reinforcement type, its size, material and pattern, rubber material properties, crimping force, effective crimping diameter etc. Minor variations in these design parameters can influence the durability of the assembly. Several trials were carried out to arrive at an optimum design of the hose and pipe assembly for automatic transmission cooling system during development phase. This paper provides guidelines developed based on test results for hose & pipe assembly development. Sensitivity of parameters such as crimping pressure, pipe flaring design, metal cap thickness, effective crimping diameter, crimping type, reinforcement size on durability of hose & pipe assembly has been discussed in detail in this paper. Optimum hose and pipe assembly designed for passenger car automatic transmission cooling system was subjected to test bench and vehicle level test.
Tongaonkar, Yogesh Manohar, Patel, Hiral, Tendulkar, Vishveshvar, Bhosale, Vikas
Transmission Breather Evaluation2019-26-03391/9/2019
Breather assembly is mounted on transmission to maintain the pressure equilibrium inside transmission. Breather allows the transmission to breathe air when the air inside transmission expands or contracts due to heating and cooling of lubricating oil during vehicle running. Breather allows the hot air to escape and cool air to enter into the transmission to prevent overheating issue. Failure of breather assembly can lead to pressure buildup inside transmission and further leading to leakage from transmission oil seals. Oil leakage through the breather assembly is governed by parameters such as opening pressure, location and orientation of breather etc. The transmission undergoes different operating conditions of input speed, load, temperature, inclination etc. Also, breather assembly is designed and positioned in such a way that there is no leakage through breather due to oil splash inside the transmission. The paper gives details of leakage issue observed at vehicle level and methodology derived to simulate on test bench. Information of vehicle level tests carried out and conditions under which leakage was observed, was used to derive a test schedule, to simulate the oil leakage issue on test rig. The transmission input speed, angle of inclination were altered during test so that the vehicle level failure is simulated on test rig. The paper also explains different trials conducted to arrive at simple and optimized design of transmission to arrest this oil leakage issue through breather. The solution proposed was again revalidated at vehicle level and results were having good correlation with rig level results. The rig level test methodology proposed in this paper can be horizontally deployed to all transmissions and subsequently lead to early capture of oil leakage issue in the development phase. Test bench validation helps to capture input early in the development time due to shorter test duration compared to vehicle level validation.
Tongaonkar, Yogesh Manohar, Patel, Hiral, Tendulkar, Vishveshvar, Bhosale, Vikas
The Influence of Friction Modifiers in Fully Formulated Motorcycle Engine Oils2018-32-002410/30/2018
Globally, emissions legislation placed on motorcycles is becoming ever more stringent [1]. One way of meeting these new regulations is to use friction modifiers (FMs) in the engine oil to reduce frictional losses in the engine. This is, however, complicated by the fact that many motorcycles use a common oil sump for both the engine and a lubricated clutch. It is often the case that if a FM reduces friction in a steel/steel contact it will also reduce friction in a steel/friction material contact. Therefore, it is usually viewed that there will be a necessary compromise between maximizing engine efficiency and maintaining efficient clutch performance. In this paper we examine the effect of a range of organic FMs on commercial fully formulated motorcycle engine oils (MCOs) using benchtop tribotests and full-scale rig tests (SAE #2 clutch test machine). The results show that by careful selection of appropriate FM chemistry it is possible to reduce steel/steel friction whilst maintaining clutch performance. To obtain a deeper understanding of the effect of FM chemical structure on the clutch friction performance the friction-speed (μ-v) behaviour of a commercial MCO formulation is investigated. It is found, in agreement with previous studies, that a lower amount of branching in the alkyl tail of an organic FM corresponds to a positive correlation between friction and speed of the type usually desired in an automatic transmission fluid (ATF). This contrasts with the μ-v behaviour of a commercial MCO intended for use in motorcycles with a wet clutch, which shows almost no correlation between friction and speed. This insight could be used to help rational design of new OFMs for motorcycle oils.
Gillespie, David, Moody, Gareth, Viadas, Aitziber
Improvement in DCT Shaft Lubrication through CFD Method04-11-03-001110/25/2018
Dual-clutch transmission (DCT) output shaft 1 (OS1) mount position is higher than the transmission lubricant level. Needle bearings and idler gears on OS1-insufficient lubrication issues and the transmission lubrication system were investigated. In the design model, the transmission housing lubrication channel and oil guide component design were studied. For numerical analysis, the STAR-CCM+ software was used to simulate transmission internal complex oil-gas multiphase transient flow morphology that monitored the four bore oil churning volumes of OS1. Finally, lubrication test results affirm simulation predictions that idler gears, needle bearings, and synchronizer rings on OS1 obtain sufficient lubrication provided that a reliable method to inspect lubrication design functions is available.
Liu, Hai, Zang, Libin
Optimization of the Lubrication Distribution in Multi Plate Wet-Clutches for HVT Transmissions: An Experimental - Numerical Approach2018-01-18229/10/2018
The paper investigates the lubrication flow within multi plate wet-clutches for hydro-mechanical variable transmissions in order to optimize the oil distribution and to reduce the thermo-mechanical stresses on the plates. Since experimental measurements are very difficult to carry out on a real system, CFD numerical tools are used for predicting the flow distribution in a real geometry under actual operating conditions. A modular approach is adopted for the domain subdivision in order to represent accurately the three dimensional geometrical features, while the volume of fluid approach is used to model the multi-phase flow that characterizes the component. Poor lubrication is predicted where high thermal stresses were observed during tests. Furthermore, the numerical modeling is validated against measurements carried out on an ad-hoc designed test rig, which adopts transparent PMMA and 3D-printed inserts for the flow investigation. Fast imaging techniques are used to capture the multiphase flow pattern within the clutch gear chamber. The testing facility replicates both the geometry of a real clutch and the actual operating conditions. A good agreement between the numerical and the experimental results is found and the analysis highlights the importance of modeling the multi-phase nature of the lubrication process for the accurate prediction of the oil distribution within multi plate wet-clutches. By means of the numerical analysis modifications to the inlet flow configuration and to the leakages’ height are developed, leading to a better oil distribution within the clutch and to a more uniform lubrication through the plates clearances.
Terzi, Stefano, Manhartsgruber, Bernhard, Milani, Massimo, Montorsi, Luca
Super Low Viscosity ATF; AW-22018-01-17569/10/2018
Reducing loss torque in automatic transmissions (ATs) is a key factor in improving fuel economy. A promising approach is to reduce the viscosity of the Automatic Transmission Fluid (ATF) so as to minimize churning loss. Aisin AW and JXTG Nippon Oil & Energy Corporation have developed a super low viscosity ATF, called “AW-2”, which has approximately 50% lower kinematic viscosity at 40 °C compared to the conventional ATF “AW-1”. It is generally understood that if the viscosity of an ATF is too low, it can have a negative impact on the fatigue life of components such as gears and bearings, and possibly lead to increased wear or seizure. AW-2 was designed to solve these problems via the application of two key technologies. The first is a high performance base oil with a low traction coefficient, which translates to low viscosity under high pressure conditions. This decreases the shear resistance between sliding surfaces under elastohydrodynamic lubrication (EHL) conditions, which contributes in improving the fatigue life of bearings and other components. The second is an ester type base oil with high polarity. It was found that the amount of ester base oil used has a major influence on fatigue life. The adsorption of esters onto metal surfaces is thought to improve lubricity in severe lubrication conditions. Durability tests were performed in a wide range of conditions, using gear and bearing components and actual transmission units, and it was confirmed that AW-2 outperforms AW-1, despite its super low viscosity. Furthermore, AW-2 reduced loss torque in the transmission by approximately 10% compared to AW-1.
Masuda, Kohei, Nakao, Hajime, Komatsubara, Hitoshi, Kurosawa, Osamu, Yamada, Katsuhito, Ishikawa, Kazunori, Mori, Atsushi
Effect of Facing Groove Design on Drag Torque of Automatic Transmission Wet Clutches2018-01-04004/3/2018
In recent years, along with growing requirement for fuel economy in relation to reduce CO2 emission, reduction of drag torque from wet clutches has been an important issue. This study observed ATF flow on friction surface under different configurations of facing using high speed camera and investigated the mechanism of drag torque using CFD analysis.
Asai, Kazunari, Ito, Takanobu
Drag and Cooling Characteristics of Circular Pin-Fin Groove Pattern of a Multi-plate Clutch Pack Using CFD2018-01-03874/3/2018
A numerical analysis of drag torque and cooling characteristics of a Multi-plate clutch pack with a circular pin fin shaped groove pattern is presented in this article. Simulations were performed using Simerics MP® platform to investigate the drag torque and heat transfer under various operating conditions. The performance characteristics of the circular pattern were later compared with various designs from the literature. Some of the groove pattern designs considered have been commonly used in transmission systems and some are from the patent literature. This study compares each design and later proposes the most efficient, that has the least drag and highest heat transfer characteristics.
Yashwanth, Bangalore Lingaraj, Ngo, Dinh, Schroeder, Debera, Hopson, Brian, Wang, De Ming
Development of New Groove Design for Reduction of Drag Torque or Spin Loss of Disengaged Wet Clutches in the High Speed Region2018-01-13004/3/2018
The typical graph of a drag torque or spin loss vs. speed of disengaged wet clutch of automotive transmission shows 4 types of trends. First one is increasing until a peak level, next decreasing to the lowest level, next saturating or being no change, and last again increasing. If the absolute value of drag torque at high speed (6000-20,000rpm) is high, the possibility of fluttering of friction disk, chipping, burning and delamination of friction materials will be high. Moreover, the efficiency of a transmission will be dropped and the life of it become shorter. Therefore, it is important to understand the physics behind the torque jump up at high speed. In our previous study, we investigated the possible reasons of torque jump up at high rotation speed. In this paper, we have extended our previous study and developed new groove design to reduce the drag toque in the high speed range. Result shows that a significant amount of drag torque in the high speed range can be reduced by a new groove design friction disk.
Pahlovy, Shahjada A., Mahmud, Syeda, Ogawa, Makoto
General Motors Hydra-Matic 9T50 Automatic Transaxle2018-01-03914/3/2018
General Motors Global Propulsion Systems’ first nine-speed automatic transmission makes its debut in the 2017 Chevrolet Malibu, advancing a legacy of multispeed transmissions designed to optimize efficiency, performance and refinement. The Hydra-Matic 9T50 nine-speed is paired with a Ecotech 2.0L Turbo engine in the Malibu, contributing to an EPA estimated 33 mpg highway, a three-percent increase over the 2016 Malibu with an eight-speed automatic paired to the same engine. The 9T50 has a wider 7.6:1 overall ratio, which is the ratio between the first gear ratio and the top gear ratio, - compared to the six-speed’s 6.0:1 ratio. The 9T50 is fitted with a “deep” 4.69 first gear ratio for excellent off-the-line acceleration and a “tall” 0.62 top gear ratio for low-rpm highway cruising. That balance optimizes acceleration and fuel economy while reducing engine noise during cruising. With nine available forward ratios, the step size between the gears is reduced providing smooth, precise upshifts and excellent refinement. Engineering features like the Selectable One Way Clutch (SOWC), step pinion gear set, and control valves integrated into the pump support allows the 9T50 to package in the same vehicle architectures as the 6T50 six speed automatic. Vehicle integration and packaging costs have been significantly reduced so interchangeability in existing vehicles will be quick and use less capital.
Martin, Thomas, Hendrickson, James
Lumped Parameter Based Thermo-Physical Modeling of Electrified Vehicle Transmission System2018-01-11954/3/2018
More stringent Federal emission regulations and fuel economy requirements have driven the automotive industry toward more efficient vehicle thermal management systems to best utilize the heat produced from burning fuel and improve driveline efficiency. The greatest part of the effort is directed toward the hybridization of automotive transmission systems. The efficiency and durability of hybrid powertrain depends on the heat generation in electric motors and their interactions among each other, ambient condition, the cooling system and the transmission component configuration. These increase the complexity of motor temperature prediction as well as the computational cost of running a conjugate heat-transfer based CFD analysis. In this paper, 1D physics based thermal model is developed which allows rapid and accurate component-wise temperature estimation of the electric motor during both steady-state and transient driving cycles. The complex and combined effect of heat convection, conduction and radiation have been considered while developing the energy conservation equations. The model represents a useful tool to design and analysis of a cooling system for the electric motors of the electrified transmission systems and thus to develop more sophisticated thermal control system strategies with variable coolant flow control devices. The critical temperature predictions from the proposed were within 10% of the real-vehicle based test data under different drive cycles.
Nahid, Mohammad, Rahman, Rezwanur, Saha, Joydip, Kapatral, Shreyas, Hossainy, Tabassum Aziz, Modi, Prashant, Rahman, Sadek
A Study on the Friction Reduction of Seal Rings for Automatic Transmission2018-01-08424/3/2018
In this study, we have developed two type of low friction seal rings (S/R). The first of developed product is textured seal ring. The surface textures with the side of seal ring are designed by using numerical analysis of hydrodynamic, and attempt to reduce the friction coefficient by lubrication improvement of sliding surface. Low friction effect is confirmed by friction torque and oil film thickness measurement, and it was discussed from analysis and experiments. The second is outer sliding type seal ring. This seal ring is unaffected by the environmental factors, it is possible to a pressure-receiving area reduction by changing the sliding surface from the side to the outer. Friction characteristics and sealing performance have been evaluated by the sliding test. Also both developed seal rings were confirmed that the low-torque effect compared to conventional one (T-shaped cross section seal ring) is obtained.
Yoshida, Yusuke, Watanabe, Koji, Seki, Kazunari, Tadano, Hikaru, Hosoe, Takeshi
Simulation to Estimate the Output Torque Characteristics and Temperature Rise of a Transmission Wet Clutch during the Engagement Process2018-01-04024/3/2018
During a typical shift event, one or more clutches are brought to engagement while others are released in order to change the torque transmission path. A mismatch in torque level and handshake timing between the off-going and on-coming clutches affects the shift quality. In order to capture the dynamic behavior of the torque response and estimate the temperature rise at the friction disk and separator plate interfaces during the engagement process, several numerical models have been developed. The earliest of these models was presented by Berger et al. which was later modified and enhanced by Natsumeda et al. and Yang et al. However, these models cannot capture the dynamic behavior of grooved clutch disks. Hence, development of a wet clutch engagement simulation model using commercial CFD simulation tool, which can capture the dynamic behaviors of no groove and grooved disks, becomes a pressing need. In this paper, we have presented an engagement simulation model using Star CCM+ simulation software and also discussed our observations from the simulation results. The key input parameters are squeeze velocity of the oil film, oil inlet temperature, initial rotating speed and flow rate. The porosity of the friction materials, friction co-efficient, compressive strain and flow factors are also taken into account. Our simulation model provides a helpful means to realize the influence of oil flow rate, rotating speed, applied pressure and groove patterns on the output torque behavior and temperature rise.
Mahmud, Syeda Faria, Pahlovy, Shahjada A., Ogawa, Makoto
In-Vehicle Characterization of Wet Clutch Engagement Behaviors in Automatic Transmission Systems2018-01-03954/3/2018
A new generation of a planetary-gear-based automatic transmission system is designed with an increasing number of ratio steps. It requires synchronous operation of one or more wet clutches, to achieve a complex shift event. A missed synchronization results in drive torque disturbance which may be perceived by vehicle occupants as an undesirable shift shock. Accurate knowledge of clutch behaviors in an actual vehicle environment is indispensable for achieving precise clutch controls and reducing shift calibration effort. Wet clutches are routinely evaluated on an industry-standard SAE#2 tester during the clutch design process. While it is a valuable tool for screening relative frictional behaviors, clutch engagement data from a SAE#2 tester do not correlate well with vehicle shift behaviors due to the limited reproducibility of realistic slip, actuator force profiles, and lubrication conditions. Advanced clutch testers with programmable slip and force controller are available for replicating torque phase and inertia phase of shifting. However, it remains a challenge to substantiate bench test data in the absence of actual clutch behaviors observed in a vehicle. This article describes the in-vehicle characterization of wet clutch engagement torque, with a focus on temperature effects during gear ratio changing. Clutch torques are accurately identified based on transmission torque measurements at input and output shafts. The analysis shows that the relationships between actuator force and clutch torque are highly non-linear with respect to transmission oil temperature, demonstrating the importance of in-vehicle clutch characterization for robust shift control. Furthermore, a squeeze film analysis is conducted to provide physical insight into clutch behaviors during torque transfer phase of shifting, where Coulomb’s linear friction model is not applicable.
Haria, Hiral, Pietron, Gregory M., Meyer, Jason, Fujii, Yuji, Wang, Pengchuan, Katopodes, Nikolaos
Parallel Thermal Management System of the Water Medium Retarder2018-01-07774/3/2018
The thermal management system of the water medium retarder using engine coolant (water and ethylene glycol) as transmission medium, omits oil-water heat exchanger in the structure. When the hydraulic retarder is operated, the valve is connected with the retarder and water pump, and then the engine coolant enters the working chamber. The kinetic energy of the vehicle is converted into internal energy of the coolant, and the heat is discharged to the external environment through the engine thermal management system. The braking torque of the water medium hydraulic retarder is determined by the water medium flow rate in the working chamber. The smaller the valve opening degree, the greater the braking torque and the faster the heating transmission fluid. Small valve opening is not conducive to the loss of heat. It will affect the normal working of the engine and hydraulic retarder. In this paper, the thermal management system of the water medium hydraulic retarder is independent of the engine. Hydraulic retarder can be controlled individually so that to improve the auxiliary braking performance. Firstly, the independent thermal management system is designed according to the heat dissipation requirement of the hydraulic retarder. Secondly, the heat transfer of the hydraulic retarder thermal management system is analyzed. Finally, compare to the thermal management system of the traditional water medium retarder and the paper. The results show that the thermal management system of parallel water medium hydraulic retarder can effectively use the radiator cooling capacity, and reduce the working temperature of the water hydraulic retarder.
Gao, Xin, Lei, Yulong, Chen, Wei, Cui, Guokai, Zhong, Lei
Lubricant Technology for Hybrid Electric Automatic Transmissions2017-01-235810/8/2017
The automotive vehicle market has seen an increase in the number of hybrid electric vehicles (HEVs), and forecasts predict additional growth. In HEVs, the hybrid drivetrain hardware can combine electric motor, clutches, gearbox, electro-hydraulics and the control unit. In HEV hardware the transmission fluid can be designed to be in contact with an integrated electric motor. One transmission type well-suited to such hybridization is the increasingly utilized dual clutch transmission (DCT), where a lubricating fluid is in contact with the complete motor assembly as well as the DCT driveline architecture. This includes its electrical components and therefore raises questions around the suitability of standard transmission fluids in such an application. This in turn drives the need for further understanding of fluid electrical properties in addition to the more usually studied engineering hardware electrical properties. New understanding around the properties of transmission fluids in electric fields has been gained. This knowledge has been used to design a fluid with the appropriate electrical characteristics coupled with those essential performance characteristics for a fluid required to lubricate a DCT unit. Such a fluid technology recently developed to be suitable for a hybrid electric DCT unit, an eDCT, is described, as well as some of the more fundamental investigations underpinning its development.
Gahagan, Michael P
Continuously Variable Transmission (CVT) Fuel Economy2017-01-235510/8/2017
Due to its simplicity and fuel economy benefit, continuously variable transmission (CVT) technology has gained a lot of attention in recent years. Market penetration of CVT technology is increasing rapidly compared to step-type automatic transmission technology. OEMs, Tier 1 suppliers, and lubricant suppliers are working to further improve the fuel economy benefit of CVTs. As a lubricant supplier, we want to understand the effects of fluid properties on CVT fuel economy (FE). We have formulated fluids that had KV100 ranges from 2-4 cSt to 7-9 cSt with various types and viscosities of base oils. Wide ranges of viscosity indexes, steel-on-steel friction, and other properties were tested. Full vehicle fuel economy tests were performed in a temperature controlled environment with a robotic driver. The test revealed that there was more than 3% overall FE variation compared to a reference fluid. Iron content analysis following each test confirmed there was no noticeable transmission wear, and average sump temperature increase was found to be more dependent on driving cycle rather than fluid.
Kwak, Yungwan, Cleveland, Christopher
Steric Effects on Tribochemical Reactivity in Detergent-Containing Lubricants under Nanoconfinement2017-01-234710/8/2017
Modern formulation in a wide variety of lubricants including engine oils and transmission fluids is designed to control friction through film-forming tribochemical reactions induced by the functional additives mixtures. Although many cases on the synergistic or antagonistic effects of additives on friction have been reported, their mechanisms are poorly understood. This study focused on the influences of metallic detergents on tribochemical reactions. We examined the mechanical properties of detergent-containing lubricants confined at a single-asperity contact and their contributions to tribochemical phenomena. We found that detergents enlarged the confinement space required for generating repulsive force and shear resistance. This means that these detergents provide steric effects under nanoconfinement at interfacial contacts. These detergents reduced friction synergistically with molybdenum dithiocarbamate (MoDTC), which is a widely used friction modifier additive that forms a slippery tribofilm. When detergents and MoDTC were mixed together in lubricants, their friction coefficient was very well correlated with the steric size. The steric size was similar to the spatial particle size of detergents measured by dynamic light scattering experiments. This suggested that steric effects were based on mechanical interference between contacting surfaces. We also found a correlation between steric size and synergy with MoDTC on non-detergent nanoparticles in the same way as detergents. These results led us to the conclusion that tribochemical reactivity of the lubricants containing detergents and MoDTC was enhanced by the steric effects under nanoconfinement. We consider that the microscopic friction between nanoparticles and solid surfaces helps MoDTC receive frictional energy to form slippery tribofilms, resulting in a synergistic reduction in friction. Such concept based on steric effects may be applicable to control many other tribochemical reactions.
Tamura, Kazushi, Sunahara, Kenji, Ishikawa, Motoharu, Mizukami, Masashi, Kurihara, Kazue
Driveline Ratio Selection and Shift Map Optimization for Automatic Transmission Vehicle at Concept Phase through Simulations06-11-01-000510/8/2017
Traditionally driveline ratios are selected based on trial and error method of proto vehicle testing. This consumes lot of time and increases overall vehicle development effort. Over last few decades, simulation-based design approach has been extensively used to alleviate this problem. This paper describes torque converter and final drive ratio (FDR) selection at concept phase for new Automatic Transmission (AT) vehicle development. Most of the critical data required for simulating vehicle performance and fuel economy (FE) targets were not available (e.g. shift map, clutch slip map, pedal map, dynamic torque, coast down, etc.) at an initial stage of the project. Hence, the risk for assuming right inputs and properly selecting FDR/Torque converter was particularly high. Therefore, a validated AVL Cruise simulation model based on an existing AT vehicle was used as a base for new AT vehicle development to mitigate the risk due to non-availability of inputs. The simulation model shows 97% correlation with the test results by using base shift map. The shift map was further optimized by using Gear Shifting Program (GSP) and FE improved by ~ 1.5% over base shift map without deterioration in performance. Finally, Torque converter and FDR were selected based on Performance and FE trade-off through simulation. The new AT proto vehicle was built with suggested configuration and Jury feedback on drivability on proto vehicle was found to be excellent. The FDR and Torque converter were subsequently confirmed to supplier for mass production. Hence, the FDR and torque converter selected by simulation met the requirements of “First Time Right” Quality Crusade while conforming to strict project deadlines.
Paulraj, Srinivasan, Muthiah, Saravanan
Statistical Modeling of Plate Clearance Distribution for Wet Clutch Drag Analysis06-11-01-000710/8/2017
Wet clutch packs are the key component for gear shifting in the step-ratio automatic transmission system. The clutch plates are coupled or de-coupled to alter gear ratios based on the driver’s actions and vehicle operating conditions. The frictional interfaces between clutch plates are lubricated with automatic transmission fluid (ATF) for both thermal and friction management. In a 10-speed transmission, there may be as many as 6 clutch packs. Under typical driving conditions, 2 to 3 clutch packs are open, shearing ATF and contributing to energy loss. There is an opportunity to improve fuel economy by reducing the associated viscous drag. An important factor that directly affects clutch drag is the clearance between rotating plates. The axial position of clutch plates changes continuously during operation. It is known in practice that not only the total clearance, but also its distribution between the plates affects the viscous drag. However, it is very difficult to measure the actual distribution for every clutch in a running transmission. Because of the limited theoretical understanding of plate movement, a fine tuning of clutch clearance design is often conducted based on trial and error during a vehicle’s development process. This article describes a statistical method for modeling the distribution of the plates in a clutch pack. The proposed method employs order statistics to represent dynamically-changing plate positions. A simulation study is conducted to investigate the effects of plate movement on open clutch drag in the slip region where ATF is present at the interface. It is shown that the model can predict the difference in drag torque with or without fixed clutch plates. The simulation results compare satisfactorily with experimental data. The model provides a mathematical insight into complex plate behaviors for open clutch drag torque analysis. The use of such a statistical model improves the fidelity of a drive cycle simulation for up-front examination of drivetrain efficiency, thus practitioners can take the impact of clearance into consideration when calibrating open clutch models.
Wang, Pengchuan, Katopodes, Nikolaos
Research on Temperature Stability of an Independent Energy Supply Device with Organic Rankine Cycles Based on Hydraulic Retarder2017-01-70039/22/2017
Hydraulic retarder, as an auxiliary braking device, is widely used in commercial vehicles. Nowadays, the hydraulic retarder’s internal oil is mainly cooled by the coolant circuit directly. It not only aggravates the load of engine cooling system, but also makes the abundant heat energy not be recycled properly. In this study, an independent energy supply device with organic Rankine cycles is applied to solve the problems above. In the structure of this energy supply device, the evaporator’s inlet and outlet is connected in parallel with the oil outlet and inlet of the retarder respectively. A part of oil enters the evaporator to transfer heat with the organic fluid, and the rest of oil enters the oil-water heat exchanger to be cooled by the coolant circuit. According to the different braking conditions of the retarder, the oil temperature in the inlet of the hydraulic retarder can be kept within the proper range through adjusting the oil flow rate into the evaporator properly. Firstly, the temperature and flow characteristics of hydraulic retarder’s internal oil are studied. Secondly, the steady-state heat transfer model of the energy supply device is established, and the distribution principle of the oil flow rate between the evaporator and the oil-water heat exchanger is proposed in order to improve the temperature stability of the energy supply device and stabilize the oil temperature in the retarder’s inlet. At last, with the multiple comparisons with the conventional structure of hydraulic retarder, comprehensive analysis of the energy supply device’s effect mechanism on the working stability of the retarder is carried out. Result shows that although this additional device increases the cost and the space requirement of the whole hydraulic retarder, it greatly improves the working stability of hydraulic retarder, and it also recovers the transmission oil’s waste-heat effectively, which reduces the energy consumption as well as the cooling load of engine cooling system.
Han, Mengzuo, Gao, Xin, Wang, Tie, Zhang, Zhiwei
SAE ARP598 and ISO 4407 Compliant Technological Advances in Wear Debris Particle Imaging for On-Site Condition Monitoring in the Aerospace Industry2017-01-21239/19/2017
The need to maintain aircraft in remote, harsh environments poses significant challenges. For example, in desert assignments or on-board carrier vessels where frequent rotation of staff with variable levels of skill and experience requires condition monitoring equipment that is not only robust and portable but also user friendly and requiring a minimum of training and skill to set up and use correctly. The mainstays of any on-site aircraft maintenance program are various fluid and particulate condition monitoring tests that convey information about the current mechanical state of the system. In the front line of these is the collection and analysis of wear debris particles retrieved from a component’s lubricating or power transmission fluid or from magnetic plugs. It is standard practice within the specialist laboratory environment to view and image wear debris using a microscope. However, it is not possible to view both macroscopic and microscopic particles at the same magnification. In addition, shallow depth of focus at high magnifications means that microscope stands must be particularly stable in order to view and capture blur-free images. Thus, a good quality microscope will weigh upwards of 20kgs.The current work has researched and developed new imaging technology that caters specifically to the need for robust, portable imaging equipment that is easy to set up and use on-site. The novel hardware/software combination is ISO 4407, SAE ARP598 and ASTM D7684 compliant with a range of on-screen magnifications from x20 to x500 and produces sharply focused one-shot images that allow both macroscopic and microscopic particles to imaged and analysed at the same magnification.
Leavers, Violet
Vehicle Idle Gear Rattle Evaluation ProcedureJ2555_201709 (Current)9/19/2017
This SAE Standard describes a procedure to be used to evaluate a disturbance known as “idle gear rattle” which can exist in vehicles equipped with manual transmissions and clutches. Other types of noises associated with operation at idle are also briefly described.
Truck and Bus Powertrain Committee
Effect of Temperature on Braking Efficiency Stability of Magnetorheological Fluid Auxiliary Braking Devices2017-01-25109/17/2017
Fluid auxiliary braking devices can provide braking torque through hydraulic damping, fluid auxiliary braking devices can also convert vehicular inertia energy into transmission fluid heat energy during the braking, which can effectively alleviate the work pressure of the main brake. Traditional hydraulic auxiliary braking devices use transmission fluids to transmit torque, however, there is a certain lag effect during the braking. The magnetorheological fluid (MR fluid) can also be used to transmit torque because it has the advantages of controlling braking torque linearly and responding fast to the magnetic field changed. The temperature of MR fluid will increase when the vehicle is engaged in continuous braking. MR fluid temperature changes will cause a bad influence on the efficiency stability of auxiliary braking. So it is necessary to clear about the effect of temperature on MR fluid auxiliary braking torque in order to keep the braking efficiency stability through torque compensated by other factors, such as changing the magnetic field strength. In order to analyze the effect of temperature on MR fluid auxiliary braking torque, this study established the mathematical model of the MR fluid auxiliary braking device through the theory of one dimensional flow theory of hydraulic retarders, and the properties of MR fluid are described based on the Bingham model. This paper researched the change of the properties of MR fluid under the same magnetic field condition with different temperatures, and summarized how much compensated torque is needed to keep the braking efficiency stability. Research showed that when the vehicle is engaged in continuous braking, the temperature effect on the braking torque is non-linear. The braking torque increases with the increase of temperature under the same magnetic field condition, the braking torque increases fast at high rotating speed of the rotor.
Xiong, Shengguang, Tan, Gangfeng, Yang, Bo, Xiao, Longjie, Xu, Yongbing, Wang, Yishi
Automotive Gear Lubricant Viscosity ClassificationJ306_201708 (Historical)8/14/2017
This SAE Standard defines the limits for a classification of automotive gear lubricants in rheological terms only. Other lubricant characteristics are not considered.
Fuels and Lubricants TC 3 Driveline and Chassis Lubrication
Engine Cooling Fan Structural AnalysisJ1390_201706 (Historical)6/1/2017
Three levels of fan structural analysis are included in this practice: a Initial Structural Integrity b In-vehicle Testing c Durability (Laboratory) Test Methods The Initial Structural Integrity section describes analytical and test methods used to predict potential resonance and, therefore, possible fatigue accumulation. The In-vehicle (or machine) section enumerates the general procedure used to conduct a fan strain gage test. Various considerations that may affect the outcome of strain gage data have been described for the user of this procedure to adapt/discard depending on the particular application. The Durability Test Methods section describes the detailed test procedures for a laboratory environment that may be used depending on type of fan, equipment availability, and end objective. The second and third levels build upon information derived from the previous level. Engineering judgment is required as to the applicability of each level to a different vehicle environment or a new fan design. This SAE Recommended Practice is applicable to any engine cooling fan application including medium and heavy-duty trucks, buses, construction equipment, industrial, and agricultural equipment. Some sections are more applicable to engine-driven fans than to hydraulic-driven or electric-motor-driven fans, especially with respect to speed control. Fan failure modes, however, are generally the same regardless of driving modes. The usage of non-metallic construction necessitates areas of evaluation not required by metallic designs. Chief among these are temperature extremes, moisture content, impact resistance, chemical attack, material purity/homogeneity, and aging/weathering. Areas of evaluation affecting both metallic and non-metallic fans, but requiring somewhat different approaches with non-metallic parts, include natural frequency determination and durability testing.
Cooling Systems Standards Committee
Oil Sheer Clutch Cuts Downtime for Metal Stamping PressTBMG-270746/1/2017
In the metal stamping business, precision, repeatability, and uptime are key. But stamping accuracy suffers when improper tension on the coil feeders incorrectly supplies metal to the presses, resulting in off-spec parts and increased rejections. ART Technologies of Fairfield, OH, relies on an oil shear clutch brake to supply constant, reliable tension on the coil feeding to one of its 400-ton presses to produce the precision and repeatability it needs, with no downtime for maintenance or adjustment. When the plant is working 20 hours a day, that uptime is as critical as the tolerances it maintains.
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