Browse Topic: Automatic transmissions

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Comprehensive Durability Assessment of Planet Carrier in Heavy-Duty Tipper Gearboxes Using RLDA Torque Data2026-26-0443To be published on 01/16/2026
In heavy-duty tippers, where challenging conditions demand high torque, planet carriers play a crucial role by enabling efficient load distribution and torque transmission while supporting gear ratio and speed variation in space-constrained systems such as automatic transmissions, hybrid drivetrains, and electric vehicles. This paper focuses on the comprehensive durability performance assessment of planet carriers using duty cycles derived from RLDA measurements for a heavy-duty tipper gearbox development program. The existing Design Validation Plan (DVP) for the planet carrier considers first gear utilization of 10-15% at 40% vehicle overload, in line with historical data. However, recent trends in mining applications revealed vehicle overloads of 55-65%, leading to an increase in first gear utilization (25-35%). This shift presents challenges for OEMs to enhance design durability while incorporating additional safety margins to meet the demands of a competitive, cost-driven market
Bagane, Shivraj, Pendse, Ameya
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
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
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
Automatic Transmission and Transaxle Committee
ENGINE, BATTERY AND VEHICLE SIMULATION STRATEGIES FOR TRANSMISSION TESTING2024-01-311711/15/2024
WHY DO WE NEED SIMULATIONS? This paper is intended to provide a broad presentation of the simulation techniques focusing on transmission testing touching a bit on power train testing. Often, we do not have the engine or vehicle to run live proving ground tests on the transmission. By simulating the vehicle and engine, we reduce the overall development time of a new transmission design. For HEV transmissions, the battery may not be available. However, the customer may want to run durability tests on the HEV motor and/or the electronic control module for the HEV motor. What-if scenarios that were created using software simulators can be verified on the test stand using the real transmission. NVH applications may prefer to use an electric motor for engine simulation to reduce the engine noise level in the test cell so transmission noise is more easily discernable.
Johnson, Bryce
An optimum solution to meet the Thermal load challenge in a high mobility military vehicle2024-26-024601/16/2024
Military vehicles are intended to operate at rugged terrains in adverse environmental conditions. Unlike a regular truck, these vehicles are powered by a much bigger engine and transmission to meet the vehicle performance parameters. Thermal systems in these vehicles are challenging. With the adverse climatic condition and driving terrains, the criticality of Engine cooling system are intensified. In this paper, a Cooling system is finalised for a high mobility military vehicle with high power engine, Automatic transmission and a hydraulic retarder. Thermal load cases are different for each. Modelling is done in thermal simulation software KULI. A steady state simulation is done for engine and automatic transmission. Transient simulation is performed for retarder. The aim is to finalise a cooling system circuit consisting of radiator, oil to air cooler and oil to water cooler which are interconnected to meet the heat load demand of engine, transmission and retarder together.
AT, SHAJAHAN, KIRAN, NALAVADATH, RAO, BONTHALA
Development of Transmission adaptor for diesel engine application2024-26-033601/16/2024
Transmission adapter is solid, located on cylinder block , on which sits the transmission housing. The function of a flexplate is to provide a mounting point for a torque converter which is used to couple the engine and transmission together when an automatic transmission is used. Transmission adapter provide access for torque convertor and flexplate assembly and protect the flexplate from external environment. Transmission adapter is also support and locate the starter. This study deals with different alloy grade material use, improvement in process to reduce porosity. Porosity observed in first samples of the proposed grade material. The study represents investigation of Transmission adaptor porosity root cause. This also included visual observation, radiography -X ray testing , analysis,3D scan, dimensional inspection, chemical analysis and comparison, tensile testing, truck testing validation tasks. Make sure critical parameter of the clearance meet between flexplate and
Karale, Pranjali
Dynamic Automatic Transmission Oil Life Prediction Using Machine Learning2024-26-003601/16/2024
Conventional resource conservation for automotive traction and its utilization to maximize efficiency is not only important but also essential for climate change. Automatic transmission fluid (ATF) is one such component, which has enough potential considering the current methods of servicing. It also plays a crucial role in the performance and longevity of the transmission system. Predicting the actual life of the ATF can be challenging due to various factors such as its application, driving conditions, driving behavior, oil grade and maintenance schedules, which can help prevent costly repairs and improve the overall performance of the vehicle. Present work is focused on developing/validating a process, which can predict critical properties of oil at any given instance and give indication to the driver/fleet owner. Data is collected for various oil properties and vehicle parameters as vehicle's usage patterns such as shift density, vehicle load, torque, current gear, lock up state
Badiger, Aishwaryalaxmi, Priyadarshi, Priyamvad, Bhat, Goutam
Controller design for path tracking of autonomous vehicle incorporating four-wheel steering system2022-01-034603/29/2022
This research aims to model and assess autonomous vehicle controller while including a four-wheel steering and longitudinal speed control. Such a modeling process simulates human driver behavior with consideration of real vehicle dynamics’ characteristics during standard maneuvers. However, a four-wheel steering control improves vehicle stability and maneuverability as well. A two-degree of freedom bicycle model, lateral deviation and yaw angle, is constructed to describe vehicle dynamics’ behavior. Moreover, a comprehensive traction model is implemented which includes an engine, automatic transmission, and non-linear magic formula tire model for simulation of vehicle longitudinal dynamics. A combination of PID longitudinal controller and fuzzy lateral controller are implemented simultaneously to track the desired vehicle path while minimizing lateral deviation and yaw angle errors. Then, A LQR based rear steering controller is introduced to represent a performance improvement over
Gafar, Ibrahim, Oraby, Walid, Aly, Mahmoud Atef
A Work in Synthesizing Simplest Planetary Gear Trains for Plug-in Hybrid Electrical Powertrain Systems for Automotive Vehicles 2022-01-081603/29/2022
Planetary gear trains (PGT) are widely used in automatic transmissions (AT), hybrid electric powertrains (HEP) and plug-in hybrid electrical powertrains (PHEP) for automotive vehicles. Plenty PGTs have been developed by the industry throughout the history of automotive vehicles. To name few which includes 6, 7, 8, 9 or 10 speeds automatic transmissions (AT) for internal combustion engine (ICE) power train systems; PGTs with two electrical machines (EM) and an ICE for single mode or multi-mode HEP systems; PGTs with single EM and an ICE for PHEP systems. Facing the new competitive challenges in motor vehicle electrification, synthesizing the simplest PGTs for PHEP become an important task. The work reported in this article is a such effort which results in much simpler, if not simplest, PGT designs for PHEPs as well as for ATs. The methodology of the synthesis works, and the details of the results will be reported.
Bai, Shushan
Mathematical Modeling of the Longitudinal motion of a Vehicle with a Continuously Variable Transmission2021-01-123709/21/2021
The Continuously Variable Transmission (CVT) is a widely adopted transmission system. It varies smoothly across a range of gear ratios and provides an automatic transmission. The operation of a CVT is simple, but successfully foretelling the longitudinal motion of a vehicle that utilizes such a transmission mechanism is sophisticated. As a result, different vehicles taking part in BAJA-SAE competitions were developed using various strategies to model the vehicle’s longitudinal dynamics and CVT operation. This article aims to provide a tool for obtaining a quantitative estimate of the longitudinal performance of a CVT-equipped vehicle and for the selection of an optimal drive-train gear ratio for such a vehicle. To this end, this article proposes a novel, relatively simple, and reasonably accurate mathematical approach for modeling the longitudinal motion of a vehicle utilizing a CVT, which was developed by a novel integration of existing vehicle dynamics concepts. The proposed
Sharma, Ayush, Tanwar, Harshit, Mittal, Ankit
Torque Weighting Vibration Dose Value to Aid Powertrain Calibration Process for Transient Torque Maneuvers2021-01-103408/31/2021
This paper investigates the application of torque weighting to vibration dose value. This is done as a means to enhance correlation of perceived drive comfort directly to driver pedal commands while rejecting uncorrelated inputs. Current industry standards for vehicle comfort are formulated and described by ISO2631, which is a culmination of research with single or multi-axis vibration of narrow or broadband excitation. The standard is capable of estimating passenger comfort to vibrations, however, it only accounts for reaction vibrations to controlled inputs and not perceived vibration request vs. response vibration. Metrics that account for torque inputs and the vibration response create actionable estimates of dosage due to driver torque requests without uncorrelated inputs. This reduces the need for additional accelerometers and special compensating algorithms when road or track testing. The use case for the proposed modified metric is during the powertrain calibration process
Furlich, Jon, Robinette, Darrell, Blough, Jason
Powertrain Design Optimization for a Range-Extended Electric Pickup and Delivery Truck02-13-03-001410/02/2020
The ongoing electrification and data-intelligence trends in logistics industries enable efficient powertrain design and operation. In this work, the commercial package delivery vehicle powertrain design space is revisited with a specific combination of optimization and control techniques that promise accurate results with relatively fast computational time. The specific application that is explored here is a Class 6 pickup and delivery truck. A statistical learning approach is used to refine the search for the most optimal designs. Five hybrid powertrain architectures, namely, two-speed e-axle, three-speed and four-speed automatic transmission (AT) with electric motor (EM), direct-drive, and dual-motor options are explored, and a set of Pareto-optimal designs are found for a specific driving mission that represents the variations in a hypothetical operational scenario. The modeling and optimization processes are performed on the MATLAB™-Simulink platform. A cross-architecture
Anil, Vijay Sankar, Zhao, Tong, Zhao, Mingjie, Villani, Manfredi, Ahmed, Qadeer, Rizzoni, Giorgio
Powertrain Design Optimization for a Range-Extended Electric Pickup and Delivery Truck02-13-03-0014-TEST-REC10/02/2020
The ongoing electrification and data-intelligence trends in logistics industries enable efficient powertrain design and operation. In this work, the commercial package delivery vehicle powertrain design space is revisited with a specific combination of optimization and control techniques that promise accurate results with relatively fast computational time. The specific application that is explored here is a Class 6 pickup and delivery truck. A statistical learning approach is used to refine the search for the most optimal designs. Five hybrid powertrain architectures, namely, two-speed e-axle, three-speed and four-speed automatic transmission (AT) with electric motor (EM), direct-drive, and dual-motor options are explored, and a set of Pareto-optimal designs are found for a specific driving mission that represents the variations in a hypothetical operational scenario. The modeling and optimization processes are performed on the MATLAB™-Simulink platform. A cross-architecture
Anil, Vijay Sankar, Zhao, Tong, Zhao, Mingjie, Villani, Manfredi, Ahmed, Qadeer, Rizzoni, Giorgio
Nissan reveals design study for next-generation Z sportscar20AUTP10_1310/01/2020
Giving hope to automotive enthusiasts that niche models will remain in at least some automakers' lineups, Nissan this week revealed the Z Proto, “signaling the company's intent to launch a new generation of the legendary Z sports car.” The production-intent Z Proto likely bears close resemblance to the production model that will replace today's 370Z, a model that has been little changed since its introduction in 2003 as the 350Z. “The Z represents the joy of driving in its purest form and has helped shape Nissan's DNA as a passionate, innovative challenger,” said Nissan CEO Makoto Uchida in a release coinciding with the Z Proto's unveiling. “Ever since the first generation, it has captured the hearts of car enthusiasts all over the world. That's why we're so excited today to be able to say to them: ‘Yes, the next one is coming!’” the CEO continued. He did not confirm when the new-generation Z-car will be in showrooms; some enthusiast media outlets indicate that will be in 2022.
Visnic, Bill
Driver Classification of Shifting Strategies Using Machine Learning Algorithms2020-01-224109/15/2020
The adequate dimensioning of drive train components such as gearbox, clutch and driveshaft presents a major technical task. The one of manual transmissions represents a special significance due to the customer’s ability of inducing high force, torque and thermic energy into the powertrain through direct mechanical interconnection of gearstick, clutch pedal and gearbox. Out of this, the question about how to capture behavior and strain of the components during real operation, as well as their objective evaluation evolves. Furthermore, the gained insights must be considered for designing and development. As a basis for the examination, measuring data from imposing driving tests are adduced. Therefore, a trial study has been conducted, using a representative circular course in the metropolitan area of Stuttgart, showing the average German car traffic. The more than 40 chosen drivers constitute the average driver in Germany with respect to age, gender and annual mileage. The used vehicle
Trost, Daniel, Ebel, André, Brosch, Erwin, Reuss, Hans-Christian
Modeling and Parameter Estimation of Automatic Transmission for Heavy-Duty Vehicle Using Dual Clutch Scheme2020-01-224209/15/2020
This paper focuses on modeling of the heavy-duty vehicle drivetrain with automatic transmission by using dual clutch scheme. The planetary gear set in the automatic transmission is complicated structure and difficult to understand. The advantage of the dual clutch scheme is that it can be used to represent the complex planetary gear set intuitively, which is a great help to understand the gear shifting process. It is also suitable for being used in the controller due to its low order. Some conditions are required to convert the planetary gear set to the dual clutch model. The heavy-duty vehicle driveline can be converted to the dual clutch model due to its heavy engine and vehicle inertia. This paper also proposes system parameter estimation methods to represent the driveline model. The main parameters are lumped inertia, lumped gear efficiency, output shaft compliance and friction coefficient of clutches. First, a method for estimating lumped inertia and lumped gear efficiency is
Lee, Tae Heon, Choi, Seibum
Parking Brake Control Identification - Vehicles with Hydraulic Brake Systems and Automatic TransmissionsJ2688_202007 (Current)07/13/2020
The scope and purpose of the SAE Recommended Practice is to provide standards for the control and indication of parking brakes in hydraulic braked vehicles over 4540 kg (10000 lb) GVWR. This recommended practice pertains to automatic transmission applications and supplements the SAE J915 recommended practice. This recommended practice does not address parking brake system performance. Parking brake system performance, both static and dynamic conditions, is the responsibility of the OEM vehicle manufacturer or manufacturers that modify the vehicle by adding special vocational required equipment (such as but not limited to outriggers, cranes, etc.).
Truck and Bus Hydraulic Brake Committee
WHAT WE'RE DRIVING20AUTP08_0707/01/2020
Before I started a drive in the 2020 Mazda3, I had to toggle the drive-select to “sport.” And release the parking brake. Each and every time. At least the two switches are in proximity on the center console. But this annoyance mars the generally good experience of the Mazda3 (all-new in 2019) and once again suggests it's a refreshing but occasionally cockeyed prism through which Mazda engineers and planners view the world.
Hybridization the highlight of Ford's all-new 2021 F-15020AUTP08_1107/01/2020
Ford in June unveiled an all-new version of its F-150, highlighted by a first-ever full-hybrid variant and the promise - but not yet specifics - of class-leading figures for the metrics that matter most to pickup customers. Even the COVID-19 pandemic couldn't stall the launch of Ford's crucial profit engine, with the new 2021 model coming to showrooms this fall from Ford plants in Dearborn, Mich. and Kansas City, Missouri. Being Ford's and the U.S.'s best-selling passenger vehicle, few risks were taken with the 2021 F-150's design, even if there is a selection of 11 new grilles. Chief designer Ehab Kaoud said in a session revealing the new pickup to the media that the 2021 F-Series is “all-new, inside and out.” That includes carrying over the current-generation F-150's pioneering use of aluminum for the body, which rides on a fully-boxed, high-strength steel ladder frame. The new aluminum bodywork may be difficult to differentiate from the current model's, but Kaoud said changes are
Visnic, Bill
A Reverse Engineering Method for Powertrain Parameters Characterization Applied to a P2 Plug-In Hybrid Electric Vehicle with Automatic Transmission2020-37-002106/23/2020
Over the next decade, CO2 legislation will be more demanding and the automotive industry has seen in vehicle electrification a possible solution. This has led to an increasing need for advanced powertrain systems and systematic model-based control approaches, along with additional complexity. This represents a serious challenge for all the OEMs. This paper describes a novel reverse engineering methodology developed to estimate relevant but unknown powertrain data required for fuel consumption-oriented hybrid electric vehicle modelling. The main estimated quantities include high-voltage battery internal resistance, electric motor and transmission efficiency maps, torque converter and lock-up clutch operating maps, internal combustion engine and electric motor mass moment of inertia, and finally front/rear brake torque distribution. This activity introduces a list of limited and dedicated experimental tests, carried out both on road and on a chassis dynamometer, aiming at powertrain
Galvagno, Enrico, Millo, Federico, DiPierro, Giuseppe, Velardocchia, Mauro, Perazzo, Alessandro, Mari, Gianluca
WHAT WE'RE DRIVING20AUTP05_0605/01/2020
The aftermarket driven by Jeep Wrangler is reportedly north of $1 billion and I like to think that my dad had something to do with kickstarting that phenomena. After purchasing a new 1947 Willys CJ2A ($1,067!), he began adding accessories that, at the time, were practical rather than fashionable - a front-mounted Koenig PTO winch, a Warn overdrive, extra driving lights and an hydraulic snowplow. Today's Wrangler buyers need only check the boxes - dozens of them - to customize their new steeds “from the factory.” On the heels of last year's launch of the Gladiator pickup body-style, Jeep has added the Mojave moneymaker to the Gladiator lineup for 2020. Although aimed at the “desert runner” vehicle trend, many “Glad Mojaves” will never see a speck of sand. Their owners will nonetheless point to their Jeeps' truly desert-capable hardware - Fox 2.5 Performance suspension dampers, Dana-44 axles with rear locker, 33-inch tires and more skid plates than a Stryker combat vehicle.
Parameter Optimization of Two-Speed AMT Electric Vehicle Transmission System2020-01-043504/14/2020
At present, many electric vehicles are often equipped with only a single-stage final drive. Although the single-stage speed ratio can meet the general driving requirements of electric vehicles, if the requirements of the maximum speed and the requirements for starting acceleration or climbing are met at the same time, the power demand of the drive motor is relatively large, and the efficient area of the drive motor may be far away from the operating area corresponding to daily driving. If the two-speed automatic transmission is adopted, the vehicle can meet the requirements of maximum speed, starting acceleration and climbing at the same time, reduce the power demand of the driving motor, and improve the economy under certain power performance. This is especially important for medium and large vehicles. Therefore, this paper considers that the working torque and speed of the motor can be changed by optimizing the speed ratio of the transmission and changing the gear position so that
Cui, Jian, Tan, Gangfeng, Feng, Jia'ao, Tian, Zhongpeng, Agyeman, Philip
Main Features of Forming the Transmission of an Active Multi-Link Road Train2020-01-042704/14/2020
The development of the economy and the associated growth in trade both within the country and international transport, the associated construction and development of transport routes using elements of intelligent transport systems constantly require increasing the efficiency of trunk transportation. In addition, the development of new economic regions with an undeveloped road network is impossible without high-capacity motor vehicles and cross-country ability. To achieve these goals, the creation of active road trains, including multi-link ones, based on non-traditional technical solutions, is required. The idea of using multi-link trains in the system of intercity and international transportation is not new. However, at the present stage of development of automotive technology requires rethinking and use of new achievements of science and technology. At present, the process of changing the design of land vehicles, qualitatively changing their structure and composition of the main
Belousov, Boris, Haritonchik, Sergey, Keller, Andrei, Bakhmutov, Sergey, Berdnikov, Alexey, Alyukov, Sergei, Alyukov, Alexander
Classification of Time Series Measurement Data for Shift Control of Automatic Transmission of Vehicles Using Machine Learning Techniques2020-01-026004/14/2020
An efficient approach to classify time series physical measurement data of shift control of automatic transmission for vehicles is presented. Comfortable acceleration is the essential factor of today’s vehicles. Shift control of automatic transmission of vehicles directly contributes to the comfortable acceleration. Since calibration of automatic transmission of vehicles is time consuming task for expert engineers, the development of autonomous calibration is desired to reduce product development period in today’s competitive automobile market. In the stage of product development, it is difficult to obtain a large amount of physical measurement data. Therefore, we need to develop machine learning method for limited amount of data. For this purpose, we develop the method to classify time series measurement data of shift control of automatic transmission of vehicles. We use support vector machine (SVM) as a machine learning technique. Features, used by SVM, of time series measurement
Morikawa, Yusuke, Ishihara, Yasuhiro, Akita, Taku, Ide, Takanori, Miyake, Noriyuki, Moriyama, Eiji, Nakagawa, Hiroshi, Tabei, Yasuo, Utsuro, Takehito
Dynamics and Control of Gearshifts in Wet-Type Dual Clutch Transmission for BEVs2020-01-076704/14/2020
The dual clutch transmission is one of the possible choices for electric vehicle drivelines. The basic principle and control mode of shifting of wet dual clutch transmission are introduced, and the dynamic process of shifting of wet double clutch transmission is studied. Combined with the dynamic model of the wet clutch engagement process, the difference between the dynamic characteristics of the dual clutch transmission modeling using the Coulomb friction model and the dual-clutch transmission model using the average flow model and the micro-convex contact theory is analyzed. The shift control strategy of the dual clutch transmission proposes a correction method to improve the shifting smoothness. Studies have shown that the torque response of the wet clutch has significant hysteresis, and the improved control algorithm can significantly improve the shifting smoothness of the wet dual clutch transmission. Based on the dynamic model of the wet clutch, the torque interruption of the
Lou, Zhenxiong, Duan, Yupeng, Zhang, Yunqing
Quantifying Engine Braking for Various Common Street Motorcycles2020-01-088004/14/2020
Motorcycle engine braking was measured in each forward gear for a cross-section of typical street motorcycles. Using GPS data acquisition and video, deceleration relative to speed was examined. Motorcycle characteristics included various engine displacements and types of motorcycle. The data acquired will give more insight into the extent which engine braking is a factor for deceleration, a topic which has not been addressed in a peer-reviewed journal article to this date.
Jansen, Henricus, LeBlanc, Beau, Wilhelm, Christopher, Shaw, Tyler, Lowi, Alvin
An LQR Approach of Automatic Transmission Upshift Control Including Use of Off-Going Clutch within Inertia Phase2020-01-097004/14/2020
This paper considers using linear quadratic regulation (LQR) for multi-input control of the Automatic Transmission (AT) upshift inertia phase. The considered control inputs include the transmission input/engine torque, oncoming clutch torque, and traditionally not used off-going clutch torque. Use of the off-going clutch has been motivated by discussed Control Trajectory Optimization (CTO) results demonstrating that employing the off-going clutch during the inertia phase along with the main, oncoming clutch can improve the upshift control performance in terms of the shift duration and/or comfort by trading off the transmission efficiency and control simplicity to some extent. The proposed LQR approach provides setting an optimal trade-off between the conflicting criteria related to driving comfort and clutches thermal energy loss. It ensures tracking a linear-like profile of oncoming clutch slip speed reference, which was found to be nearly optimal based on control trajectory
Cvok, Ivan, Deur, Josko, Ivanovic, Vladimir, Zhang, Yijing, Fujii, Yuji
An Intuitive Derivation of the Dual-Clutch Model for Clutch Shift Dynamics2020-01-043304/14/2020
There are several commercial off-the-shelf software available to study transmission and driveline dynamics. Many of these software require a faithful representation of the transmission topology in order to carry out the analyses. This approach utilizes several redundant degrees of freedom which may not be necessary for studying low frequency (<~30 Hz) dynamics and may be computationally inefficient. The dual-clutch model has been proposed as a generic 2-DOF model that overcomes some of these drawbacks. In this paper, the dual-clutch model is initially derived from first principles, starting with the equations of motion for a planetary automatic transmission. The model coefficients - the inertia matrix and the matrix of clutch gains - are then derived using a more intuitive approach and compared to the model derived from first principles.
Attibele, Pradeep
Launch and Lock with Multi-input Multi-Output Converter Control2020-01-026204/14/2020
A torque converter is a type of fluid coupling device used to transfer engine power to the gearbox and driveline. A bypass clutch equipped in a torque converter assembly is a friction element which when fully engaged, can directly connect the engine to the gearbox. The torque converter is an important launch device in an automatic transmission which decouples engine speed from gearbox input speed while provides torque multiplication to drive the vehicle. During partial pedal launch, it is desired to engage the bypass clutch early and reduce the converter slippage in order to reduce power loss and achieve better fuel economy. However, engaging the bypass clutch early and aggressively may disturb the wheel torque and cause an unpleasant driving experience. This paper describes a multi-input multi-output (MIMO) control method to coordinate both engine and converter bypass clutch to simultaneously deliver desired wheel torque and reduce converter slippage. This control method leverages a
Xu, Yang, Chen, Weitian, Ford, Stuart, Liu, Pinzhi, Dai, Edward, Keller, Bret, Jiang, Hong
A Study on the Development of the CPA (Centrifugal Pendulum Absorber) Reducing the Rattle & Booming Noise in the Manual Transmission Vehicle2020-01-039704/14/2020
In recent years, the automotive engine strategies are forced on downsizing and down speeding to enhance fuel economy and reduce the emission. These make torque increase significantly in order to improve the vehicle performance, especially in diesel engines. At this time, the torsional damper performs the most important role in the driveline NVH of the manual transmission system. The clutch disk with torsional dampers is not easy to be applicable to the high torque of low speed RPM range. And* DMF with sufficient isolation of vibrations of driving system includes disadvantages of the expensive cost, delayed response, and engine NVH aspect deteriorated due to increase of angular acceleration of engine. This paper presents that the Centrifugal Pendulum Absorber (CPA) is applied to maximize the isolation and to compensate for the disadvantages of DMF and SMF system. Furthermore, CPA was developed for the first time in the world on SMF clutch discs in manual transmission.
Kim, Ukjin
Mathematical Analysis of Clutch Thermal Energy during Automatic Shifting Coupled with Input Torque Truncation2020-01-096704/14/2020
A step-ratio automatic transmission alters torque paths for gearshifting through engagement and disengagement of clutches. It enables torque sources to run efficiently while meeting driver demand. Yet, clutch thermal energy during gearshifting is one of the contributors to the overall fuel loss. In order to optimize drivetrain control strategy, including the frequency of shifts, it is important to understand the cost of shift itself. In a power-on upshift, clutch thermal energy is primarily dissipated during inertia phase. The interaction between multiple clutches, coupled with input torque truncation, makes the decomposition of overall energy loss less obvious. This paper systematically presents the mathematical analysis of clutch thermal energy during the inertia phase of a typical single-transition gearshift. In practice, a quicker shift is generally favored, partly because the amount of energy loss is considered smaller. However, the analysis reveals that there is a critical input
Zhang, Yijing, Fujii, Yuji, Hippalgaonkar, Rohit, Cvok, Ivan, Ivanovic, Vladimir, Deur, Josko, Ranogajec, Vanja
Feedback Control of Synchronizers for Reducing Impacts during Sleeve to Gear Engagement2020-01-096004/14/2020
This paper presents a feedback control strategy aimed to reduce noise and wear during gearshifts in conventional and hybrid Dual Clutch Transmissions (DCT and DCTH) and Automated Manual Transmissions (AMT). The control strategy is based on a new dog teeth position sensor developed by China Euro Vehicle Technology AB and existing speed sensors in the transmission. During gear shifting, noise is generated by impacts between the sleeve teeth and the idler gear dog teeth after speed synchronization. Besides noise, these impacts are also responsible for delaying the completion of shift and contribute to wear in the dog teeth, hence reducing the lifespan of the transmission. The presented control strategy controls speed synchronization such that the impact between sleeve and idler gear dog teeth, before the start of torque ramp up, is avoided. Since drag torque is an important factor in speed synchronization, this paper also contains an algorithm to identify friction torque coefficient in
Piracha, Muddassar Zahid, Grauers, Anders, Hellsing, Johan
Sweating the details OF C8 DEVELOPMENT20AUTP04_0304/01/2020
How GM's Corvette engineers tackled challenges in the move to a mid-engine architecture. Shifting 500 lb (227 kg) of engine mass rearward by 7.5 feet (2.3 m) and moving 300 lb (136 kg) of transmission components aft by almost three feet transformed the 2020 Chevrolet Corvette Stingray into a budding supercar. General Motors' motive behind adopting a mid-engine layout for the eighth-generation (C8) Corvette was to improve acceleration, braking and handling via substantially increased rear-tire loading. While numerous test-drive reviews and ‘Of the Year’ trophies mark that mission accomplished, there are lessons behind the hoopla: how GM engineers solved problems they encountered reinventing America's sports car. “Porsche was our primary benchmark, especially in reference to their PDK dual-clutch automatic transmission's overall dynamics,” revealed executive chief engineer Tadge Juechter, in an interview with SAE's Automotive Engineering. He said GM also purchased a Ferrari 458 for
Sherman, Don
Nissan's 2020 Frontier gets new V6, 9-speed20AUTP03_1503/01/2020
More transmission gears and greater engine horsepower should enliven the 2020 Nissan Frontier midsize pickup truck. “We're launching a new transmission and new engine in the current Frontier, and this powertrain will be the heart of the next-generation Frontier coming in 2021,” said Tiago Castro, Nissan North America's director of commercial business unit for pickup trucks, SUVs and vans. Castro spoke with Automotive Engineering during the 2020 Chicago Auto Show. Replacing the current standard 152-hp 2.5-L 4-cylinder and an optional 261-hp 4.0-L V6, the 3.8-L V6's first application is the 2020 Frontier. “We're getting 49 more horsepower with the new V6, which is best-in-class standard horsepower,” Castro said. The new 3.8-L engine's torque, rated at 281 lb-ft (381 Nm), matches the outgoing 4.0-L V.6.
Buchholz, Kami
Two-Speed Transmission Gear Shift Process Analysis and Optimization Using Genetic Algorithm08-09-01-000101/16/2020
Electric Vehicle (EV) equipped with two-speed transmission has benefit in improving dynamic performance and saving battery consumption. However, during gear shift process, torque interruption and shift impact may lead to a bad shift quality. This work investigates gear shift process in an Automated Manual Transmission (AMT) configuration-based two-speed transmission. First of all, a typical gear shift process is analyzed. Parameters like motor speed, shift force, motor torque change rate, and speed difference between synchronizer and target engage gear are all included to find the relationships with shift duration. Then vehicle jerk is introduced as a criterion to evaluate shift impact. Besides, a comprehensive shift control strategy is developed. While keeping the output torque at wheels unchanged, the shift strategy also improved motor working efficiency after gear shift. Therefore, to determine an optimum shift strategy and achieve a balance among different parameters, Genetic
Cao, Zhan, Yang, Jiansen, Wang, Xinyu
Dynamic modeling and simulation of a powertrain system with a six-speed automatic transmission2019-36-010001/13/2020
The constant growth of the automotive market demands for comfort to the user and energy efficiency have caused the intensification of the industry researches and development of the automatic transmissions (AT). However, vehicles equipped with these gearboxes entails in higher fuel consumption levels than the one required by vehicles equipped with manual transmission. In the automotive industry due to the advantages offered using computer simulations, such as fast evaluation an optimization, many researchers are using virtual models for optimization of dynamic behavior of systems and fuel consumption. Aiming to study the dynamic behavior of an AT and the influence of its components on that behavior, this paper presents an AT dynamic model developed in MATLAB® / Simulink®. The AT model has three main subsystems: a torque converter model, which includes the dynamic of both the forward flow mode and the reverse flow mode; a Lepelletier gearbox model, composed by a set of three planetary
de Araujo, Marcel T. da S., Falleiros, Murilo F., Gioria, Gustavo dos S.
Inside Tremec's SUPERCAR DCT20AUTP02_0401/01/2020
To polish the 2020 mid-engine Corvette's driving prowess, GM and Tremec engineers joined forces to create a new and better automated transaxle. Explaining Corvette's move to one transmission for all buyers, global chief engineer Tadge Juechter notes, “Our customers began requesting a dual-clutch automatic transmission [DCT] several years ago. Following the introduction of the C7 Corvette in 2014, our take-rate for sticks [manual gearboxes] fell from 50 percent to less than 20 percent this year.” Searching the globe - read Europe - for a suitable DCT, Juechter's team found none with sufficient torque capacity to survive behind the lively LT2 6.2-L V8 planned for the all-new 2020 mid-engine edition of GM's reimagined sports car. To solve that dilemma, discussions began with Tremec, the Mexico City-based manufacturer which has supplied GM, Ford and FCA with manual transmissions for two decades. While Tremec had the expertise to make the mechanical components packed inside a dual-clutch
Sherman, Don
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
Kwak, Yungwan, Cleveland, Christopher, Adhvaryu, Atanu, Fang, Xinggao, Hurley, Susie, Adachi, Tsuneo
Advanced Bench Test Methodology for Generating Wet Clutch Torque Transfer Functions for Enhanced Drivability Simulations2019-01-234012/19/2019
A wet clutch continues to play a critical role for step-ratio automatic transmissions and finds new utilities in hybrid and electrified propulsion systems. A torque transfer function is often employed in practice for sophisticated clutch slip controls. It provides a simple, yet practical framework to represent clutch torque as a function of actuator force. An accurate transfer function is also increasingly desired in today's vehicle design process to enable upfront assessment of clutch controls through simulations. The most common approach is based on Coulomb's linear friction model, where the coefficients are adaptively identified based on vehicle data. However, it is generally difficult to tune Coulomb's model for hydrodynamic behaviors even if the reference vehicle data are available. It also remains a challenge to produce in-vehicle clutch behaviors on a component test bench to determine realistic transfer function before prototype vehicles are built. SAE#2 test procedure is the
Haria, Hiral, Fujii, Yuji, Pietron, Gregory M., Sun, Anna, Tsuchiya, Takahiro, Miyagawa, Masatoshi, Nakamura, Shinji, Wendel, Matthew, Miyoshi, Hiroya, Wang, Pengchuan, Katopodes, Nikolaos
Hydrodynamic Drives TerminologyJ641_201912 (Current)12/02/2019
Since the torque converter and fluid coupling are commonly used components of automatic transmissions in industry, the SAE appointed a committee to standardize terminology, test procedure, data recording, design symbols, and so forth, in this field. The following committee recommendations will facilitate a clear understanding for engineering discussions, comparisons, and the preparation of technical papers. The recommended usages represent the predominant practice or the acceptable practice. Where agreement is not complete, alternates have been included for clarification. EXAMPLE: Two systems of blade angle designations are described. Consequently, when a blade angle is specified, the system should be designated. This SAE Recommended Practice deals only with the physical parts and dimensions and does not attempt to standardize the design considerations, such as the actual fluid flow angle resulting from the physical blade shape.
Automatic Transmission and Transaxle Committee
Automatic Transmissions - Schematic DiagramsJ647_201911 (Current)11/19/2019
The following schematic diagrams reflect various methods of illustrating automotive transmission arrangements. These have been developed to facilitate a clear understanding of the functional interrelations of the gearing, clutches, hydrodynamic drive unit, and other transmission components. Two variations of transmission diagrams are used: in neutral (clutches not applied), and in gear. For illustrative purposes, some typical transmissions are shown.
Automatic Transmission and Transaxle Committee
Study on Engine Start Vibration Index in a Hybrid Powertrain Using Torque Sensor and Cylinder Pressure Sensor2019-01-503411/04/2019
This paper presents an investigation of drivability issue of engine start-stop. Hybrid vehicles provide excellent benefits regarding fuel efficiency and emission. However, vibration results from constant engine start and stop events generate drivability issues, thus compromising driving comfort. This paper has designed a high speed torque sensor to capture instantaneous torque at the engine shaft. Its consequences help to find out the most suitable index of vibration severity. This paper is organized in four sections. The first section introduces the powertrain to be studied. The second section introduces development of a specially designed torque sensor. The torque sensor is installed between the engine and ISG (Integrated Starter Generator), alongside with an encoder. The torque sensor is utilized to collect the instantaneous shaft torque on occasion of engine start. In the third section, this paper has performed two experiments. Firstly, a typical engine start process (from 0 to 650
Yang, Fuyuan, Du, Lei, Hu, Yaodong
WHAT WE'RE DRIVING19AUTP11_0811/01/2019
While I'm among the first media to have driven the mid-engine 2020 Stingray, my time in the car (during the North American Car, Truck and Utility of the Year judging) was but 45 minutes. A very invigorating 45 minutes. My Torch Red coupe came with a special feature: Corvette ride-and-handling engineer Mike Hurley, who rode shotgun with me through the Michigan countryside. As we discussed C8 development, Mike schooled me on the magneto-rheological (MR) dampers that underpin the desirable $5,000 Z51 performance package. With three driver-selectable suspension modes - Tour, Sport, Track - the MR dampers deliver a compliant ride in town and plushness on the open road, while transforming the car into a sharp track-day tool. Crossing railroad tracks is no longer torture in a Corvette.
Performance Analysis of an Automated Manual Transmission Controller for Two-Wheeler2019-28-012510/11/2019
This research paper presents controller development and its performance analysis for two wheeler. The comparison for different performance parameters is carried out with and without automated manual transmission (AMT) controller. The AMT considered in this case, includes a conventional manual transmission gear-box with conventional clutch pedal. It is equipped with clutch actuation with the help of linear actuator and the gear shifting using servo motor. The upshift and downshifting of the gears and the clutch actuation is done through the decisions of controller. The results generated during the engine dynamometer test are used as input creating two wheeler vehicle model using AVL cruise software. This vehicle model is used to predict vehicle performance. The vehicle performance results are validated with chassis dynamometer test data. The vehicle model is modified for generation of gear shifting plot. Also Gear shift program (GSP) is generated using the GSP generation module of AVL
Patil, Saurabh Sunil, Wani, Kiran Pralhad
Fuel Efficiency Improvement in Automatic Transmissions by Lockup Slip Methodology2019-28-002910/11/2019
Increasing of automatic transmissions in passenger cars is based on pleasure of driving, smooth acceleration and easy operation makes the customer satisfaction. Challenges beyond 2020 is BS VI emission norms in India - a very tough goals on CO2& NOx reduction in Gasoline & Diesel vehicles. But its setback in lower fuel economy. To support & enhance fuel economy in Automatic transmissions as part of drivetrain technologies, this article discusses about the power losses in torque converters and experiments on the actual Automatic transmission (AT) vehicle on-road to understand the real city driving behavior in the aspects of gear utilization & gas pedal utilization throughout the entire traffic conditions. With that data research, slip area and slipping conditions is determined & clutch slip control is enabled at area in torque converter by ensuring that NVH parameters are not affected. The addition of the Lock-up Slip system add value in terms of “Joy of Driving” by providing a 2-3
Sukumar, Arun
Domestic Performance Torque Converter ManufacturingJ2440_201910 (Current)10/09/2019
The scope of this SAE Draft Technical Report is to establish dimensional standards for high-performance domestic torque converter manufacturers. Many torque converter manufacturers build converters to their own standards. Some of these standards may be outside of the specifications that define a quality performance torque converter.
Motor Vehicle Council
Rectangular Cross Section Polymeric Sealing RingsJ2310_201910 (Current)10/09/2019
The purpose of this SAE Recommended Practice is to establish guidelines for the automatic transmission and hydraulic systems engineer to design rectangular cross section seals for rotating and static grooved shaft applications. Also included are property comparisons of polymeric materials suitable for these applications. Historically, material covered in this document is not intended to include aluminum contact applications.
Automatic Transmission and Transaxle Committee
Ford revisits OHV layout, big displacement for new commercial-truck V819TOFHP10_0910/01/2019
In a still-heated market for highly profitable heavy-duty pickups and commercial vehicles, Ford doesn't intend to be outdone by General Motors' and FiatChrysler's recently-launched new efforts, announcing the power and torque figures for its all-new 7.3-L gasoline V8 for its 2020 models and reminding that major revisions for 2020 for its Power Stroke diesel V8 also portend to increased power. At a late-July media event, Ford revealed that the new 7.3-L, which revives the overhead-valve layout Ford largely abandoned years ago for gasoline engines, generates 430 hp at 5500 rpm and 475 lb-ft (644 Nm) at 4000 rpm. The figures conveniently slip past the 401 hp and 464 lb-ft (629 Nm) available from GM's 6.6-L gasoline V8 and the 410 hp and 429 lb-ft (582 Nm) FCA deals out with its 6.4-L Hemi V8-both of which, it may be no coincidence, also are OHV designs.
Visnic, Bill
Engineering the 2020 CHEVROLET CORVETTE19AUTP09_0109/01/2019
The eighth-gen (C8) Corvette is a creative mix of novel and traditional technical solutions unleashed at a shockingly low base price. Two days before the 50th anniversary of astronaut Neil Armstrong's leap for mankind and 10 years after General Motors emerged from bankruptcy, the camouflage was finally ripped from the eighth-generation (C8) 2020 Chevrolet Corvette. As widely anticipated, C8 now flaunts a mid-engine layout that ostensibly puts it on equal terms with the world's most venerated supercars. After six decades of experimentation and concept-car teasing, GM acknowledged that the new Stingray will enter production before year's end. The truly shocking announcement is a base price of $59,995 including destination, only $3,000 more than today's front-engine C7. Along with moving the cockpit forward 16.5 inches (419 mm) to facilitate shifting the engine rearward, the new Corvette is an innovative mix of novel and traditional engineering solutions.
Sherman, Don
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