Browse Topic: Torque converters

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An LQR Approach of Automatic Transmission Upshift Control Including Use of Off-Going Clutch within Inertia Phase2020-01-09704/14/2020
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 optimization results. A special attention is given on proper implementation of nonlinear energy loss term through LQR cost function cross term and using a clipped optimal control approach to provide that the clutches (described as torque source elements) can only dissipate energy. The LQR approach was applied to a fifth-order powertrain model and different upshift control scenarios ranging from the use of single clutch towards using both clutches and transmission input/engine torque reduction. It is shown that the LQR approach can reproduce Pareto frontiers obtained by multi-objective control parameter optimization demonstrating that apart from being used in closed loop controls, the proposed LQR approach can also be exploited for computationally efficient (off-line) optimization purposes.
Cvok, Ivan, Deur, Josko, Ivanovic, Vladimir, Zhang, Yijing, Fujii, Yuji
Development of GM Allison 10-Speed Heavy Duty Transmission2020-01-04384/14/2020
This paper describes the development of the GM Allison 10-Speed Heavy Duty (HD) Transmission. The trend of increased towing capacity and engine horsepower in the automotive heavy-duty truck segment has been steadily climbing for the past 10 years. The development of 10-Speed HD Transmission is designed to be best in class in for towing performance in the 2500/3500 series segment while optimizing fuel economy. The 10-Speed HD Transmission also gives the customers the option to order an integrated power take-off (PTO) unit that benefits downstream installation of utility accessories such as hydraulic pumps, generators, etc.
Lee, Chi Teck, Ames, David, Caldwell, Brett, Knoth, Matthew, Reinhart, Timothy, Kelly, Jeffrey, Kannan, Rajesh, Tanasi, German
Inside Tremec's SUPERCAR DCT20AUTP02_041/1/2020
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 box, the automated half of the equation - mechatronic actuators to engage the clutches and shift the gears - was beyond their ken. Tremec filled that need in 2012 by purchasing Hoerbiger Drivetrain Mechatronics, a Belgium-based supplier of electronic dual-clutch actuators with a customer list including AMG-Mercedes, Ferrari and McLaren.
Sherman, Don
Hydrodynamic Drives TerminologyJ641_201912 (Current)12/2/2019
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
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% improvement in fuel economy over the previous one.
Sukumar, Arun
Domestic Performance Torque Converter ManufacturingJ2440_201910 (Current)10/9/2019
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
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
Integrated Multi-Physics Simulation for Full-Vehicle Low Frequency NVH Optimization in HEVs2019-01-14556/5/2019
The recent automotive industry trend towards electrification has created new challenges for NVH engineers. These challenges stem from new powertrain architectures and their complex interactions, the governing control strategies which aim to optimize energy management, and new unmasked sources of excitation. Additionally, vehicle manufacturers are attempting to reduce hardware testing in order to rapidly satisfy increasing production demand and to minimize its costs. Hence, to meet the above-mentioned challenges up front in the development process of Hybrid Electrical Vehicles (HEVs) while balancing competing design objectives of drivability, durability and NVH, a simulation-led design and optimization is required. NVH problems are often the result of mechanisms that originate through complex interactions between different physical domains (flow, electromagnetic, structural/mechanical, control logic, etc.) and the assembly of individual components into a complete system. Therefore, accurate system-level integrated models are becoming a requirement to solve modern NVH problems. Combining the optimal balance between simulation and experimental data, this article describes a joint effort between Ford and Gamma Technologies to develop a general methodology to perform full-vehicle low frequency NVH analysis. Using GT-SUITE software, a non-linear multi-physics simulation model of a rear wheel drive HEV was created. The model was exercised to accurately evaluate the effects of powertrain control strategy and component selection on low-frequency NVH performance during a tip-in regeneration, downshifting and in-gear acceleration maneuvers while minimizing the computational cost.
Gomez, Llorenc Foraste, Zeman, Jonathan, Liu, Jack
Systematic CFD Parameter Approach to Improve Torque Converter Simulation06-12-02-00084/8/2019
A systematic parametrization approach was employed to simulate a torque converter operating over a wide range of speed ratios. Results of the simulation yielded torque converter impeller and turbine torques prediction errors below 11% when compared to manufacturer data. Further improvements in the computational fluids dynamic (CFD) model reduced such errors down to 3% for the impeller and 6% for the turbine torque predictions. Convergence was reached well under 300 iterations for the most optimal variable setting, but each speed ratio was let to run for 300 iterations. Solution time for the 300 iterations was 40 minutes per speed ratio. The systematic parametrization provides a very competitive procedure for torque converter simulation with reduced computational error and fast solution time.
De Jesus Rivera, Edward, Robinette, Darrell L., Blough, Jason R., Anderson, Carl L., Frait, Steve
Quantifying the Effect of Initialization Errors for Enabling Accurate Online Drivetrain Simulations2019-01-03474/2/2019
Simulations conducted on-board in a vehicle control module can offer valuable information to control strategies. Continued improvements to on-board computing hardware make online simulations of complex dynamic systems such as drivetrains within reach. This capability enables predictions of the system response to various control actions and disturbances. Implementation of online simulations requires model initialization that is consistent with the physical drivetrain state. However, sensor signals and estimated variables are susceptible to errors, compromising the accuracy of the initialization and any future state predictions as the simulation proceeds through the numerical integration process. This paper describes a drivetrain modeling and analysis method that accounts for initialization errors, thereby enabling accurate simulations of system behaviors. First, the hybrid dynamical system paradigm is employed to develop a torsional drivetrain model that captures the dynamics during a gear shift. The model is constructed in an analytical form and linearized to enable online mathematical analysis. Then a methodology is introduced to quantify the effect of initialization errors online. Finally, a procedure to systematically account for initialization errors is discussed. The outcome of this study demonstrates the capability for enabling accurate online simulations in the presence of sensor and state estimation errors in drivetrain applications and beyond.
Yang, Hang, Kidambi, Narayanan, Wang, Kon-Well, Pietron, Gregory M., Hippalgaonkar, Rohit, Fujii, Yuji
A Generalized Component Efficiency and Input-Data Generation Model for Creating Fleet-Representative Vehicle Simulation Cases in VECTO2019-01-12804/2/2019
The Vehicle Energy Consumption calculation Tool (VECTO) is used for the official calculation and reporting of CO2 emissions of HDVs in Europe. It uses certified input data in the form of energy or torque loss maps of driveline components and engine fuel consumption maps. Such data are proprietary and are not disclosed. Any further analysis of the fleet performance and CO2 emissions evolution using VECTO would require generic inputs or reconstructing realistic component input data. The current study attempts to address this issue by developing a process that would create VECTO input files based as much as possible on publicly available data. The core of the process is a series of models that calculate the vehicle component efficiency maps and produce the necessary VECTO input data. The process was applied to generate vehicle input files for rigid trucks and tractor-trailers of HDV Classes 4, 5, 9 and 10. Subsequently, evaluating the accuracy of the process, the simulation results were compared with reference VECTO results supplied by various vehicle manufacturers. The results showed that the difference between simulated and reference CO2 emissions was on average -0.6% in the Long Haul cycle and 1% in the Regional Delivery. Such a process could be a powerful tool for calculating HDV CO2 emissions for development and analysis purposes, e.g. for new vehicle prototypes or multistage vehicles, and for creating VECTO equivalent models that can be used to assess alternative operating conditions and mission profiles of existing vehicle models. The methodology was applied for creating input of various components in the US tool for HDV certification, GEM, for generic sample-vehicle models available.
Zacharof, Nikiforos, Tansini, Alessandro, Prado Rujas, Iker, Grigoratos, Theodoros, Fontaras, Georgios
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
Ford engineers a tech barrage with 2020 Lincoln Aviator19AUTP01_161/1/2019
Ford Motor Co. officially launched its 2020 Lincoln Aviator at the 2018 Los Angeles auto show, with the all-new three-row midsized luxury SUV featuring a barrage of equally new and significant technologies. Production is slated for 3Q 2019 at Ford's Chicago assembly complex. Aviator debuts Ford's first RWD/AWD vehicle platform, coded CD6, that was engineered from a clean sheet to support both conventional gasoline-ICE and plug-in hybrid models. It also features the much-anticipated electrified variant of Ford's 10R 10-speed automatic transmission, which will also be used to “hybridize” the F-Series pickup. Known internally as MHT (modular hybrid transmission), the electrified 10R packages the e-motor on the input side, between the engine and gearset. It retains its torque converter. Non-hybrid Aviators will use the conventional 10R60 unit.
Brooke, Lindsay
Commercial Truck and Bus SAE Recommended Procedure for Vehicle Performance Prediction and ChartingJ2188_201807 (Current)7/25/2018
This SAE Recommended Practice takes into account modern standardized methods for collecting and summarizing data that has an effect on vehicle steady-state performance, such as engine output (gross and net), transmission losses, drivetrain efficiency, vehicle aerodynamic devices for various vehicle and body configurations, as well as road surface variations and air density variations resulting from altitude and barometric effects. The procedure does not address vehicle transient performance (acceleration, braking, and cornering), because of the considerable amount of additional data required such as moment of inertia of all the rotating parts. Nor does it address vehicles with torque converters and automatic transmissions. This document is, therefore, intended for vehicles having fixed-ratio type transmissions and positive engagement clutches. Metric and ISO unit conversions are provided in the metric conversion tables at the end of this procedure (see Appendix B). Some modern vehicles with electronic engine controls have the ability to vary the maximum engine revolutions for each gear, as well as permitting the power or rpm to increase if more time is spent in the lower gears, as when climbing a grade. These special cases can be handled by this procedure, just by customizing the data for each transmission ratio and superimposing the long-term data on top of the instantaneous data. All of the equations are written in a form suitable for programming into a mainframe or desk-top computer, using a spreadsheet/database or a higher level language, such as Basic, Fortran, Pascal, C or Unix, etc. However, they are simple enough, to be performed on a hand-held calculator.
Truck and Bus Powertrain Committee
Interior Noise Refinement in an ICV Bus through Driveline Torsional Vibration Analysis2018-01-14726/13/2018
With a push for urbanization across cities, there is an increased demand for mobility in public transportation especially buses which are provided through state transport undertakings. Hence, the expectations of this class of vehicles will be high in terms of quality and comfort to the passengers. The noise inside the passenger area of the bus becomes an important parameter, which sets apart a bus manufacturer from its competitors. The driveline of the bus is the system responsible for the transfer of power from engine to the wheels. The noise and vibration problems associated with it are detected only in the late stages of the design chain, when all its elements are tested together over a wide range of conditions. Since, calibration of engine and the selection of transmission is freezed in early stages, satisfying power and torque requirements, the only viable option left to address the problem is by optimizing the clutch parameters. Combustion in multi-cylinder four stroke diesel engine produces periodically changing gas and inertia forces associated with reciprocating pistons. This leads to fluctuation in the engine speed and the torque transmitted by the engine, inducing torsional vibrations into the system. These torsional vibrations make the unloaded gear pairs of the gearbox to impact against each other generating Gear rattle noise. In the present work, an abnormal noise was observed in an ICV (Intermediate Commercial Vehicle) bus at both idling and driving conditions. Near source noise measurements and interior noise measurements were carried out to determine the source of the noise. Torsional vibration levels were also measured at engine and gearbox. Upon identification of the source, the clutch parameters including the clutch torsion spring stiffness was scrutinized and modified. This gave improvement in the interior noise levels inside the passenger area of the bus.
Kamani, Keval, Kannan, P, P, Sivaraman
Classification of Time Series Measurement Data for Lock-Up Clutch of Automatic Transmission of Vehicles Using Deep Convolutional Neural Networks2018-01-03994/3/2018
A newly developed classifying method for time series measurement data of automatic transmission of vehicles is presented. The proposed method uses deep convolutional neural networks to learn what is comfortable acceleration. In addition, our proposal method employs supervised learning based on experienced engineer’s criterion. As a demonstrative problem, we consider the classification of time series measurement data for lock-up clutch control of an 8 speed automatic transmission.
Kawakami, Takefumi, Ide, Takanori, Tomita, Kiyohisa, Moriyama, Eiji, Tsutsui, Hiroshi, Hoki, Kunihito, Muramatsu, Masakazu
Structural Analysis Based Sensor Placement for Diagnosis of Clutch Faults in Automatic Transmissions2018-01-13574/3/2018
This paper describes a systematic approach to identify the best sensor combination by performing sensor placement analysis to detect and isolate clutch stuck-off faults in Automatic Transmissions (AT) based on structural analysis. When an engaged clutch in the AT loses pressure during operation, it is classified as a clutch stuck-off fault. AT can enter in neutral state because of these faults; causing loss of power at wheels. Identifying the sensors to detect and isolate these faults is important in the early stage of the AT development. A universal approach to develop a structural model of an AT is presented based on the kinematic relationships of the planetary gear set elements. Sensor placement analysis is then performed to determine the sensor locations to detect and isolate the clutch stuck-off faults using speed sensors and clutch pressure sensors. The proposed approach is then applied to a 10-Speed AT to demonstrate its effectiveness. A simulator is developed to qualitatively study the effects of clutch stuck-off faults on speeds of different elements in an AT. Simulator results are presented to support the sensor placement analysis. Later, a comparative analysis of different sensor sets based on the cost and performance is conducted to choose the optimal sensor combination. This paper concludes by discussing in detail the different sensor sets that give different fault isolation performance and suggests that only increasing number of sensors does not guarantee better fault isolation.
Deosthale, Eeshan Vijay, Ahmed, Qadeer, Arasu, Mukilan, Rizzoni, Giorgio, Mohammed, Majed, Hathaway, Richard
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
Correlation of “Non-Zero” Speedometer Readings with EDR Data2018-01-05224/3/2018
Observations made during forensic automotive crash investigations have identified instances of non-zero, post-crash speedometer readings and created questions as to the validity of the indicated speed relative to the vehicle speed at impact. Previously published work has addressed many issues related to the reliability of non-zero, post-crash speedometer readings identified in vehicles as well as motorcycles. Much of this work established criteria that related the reliability of the post-crash needle position to the design of the stepper motor that controls the needle. Part of this criteria is related to the static torque associated with the speedometer needle shaft rotation due to outside (crash) forces. The published criteria were evaluated in staged crash tests which investigated the ability to maintain needle position under longitudinal and lateral forces after an electrical power loss. In an effort to extend the science, this paper compares non-zero, post-crash speedometer readings with event data recorder (EDR) data from twenty-one real-world crashes where both non-zero, post-crash speedometer readings and EDR data were available. Results from this study suggest a positive correlation between non-zero speedometer readings and vehicles experiencing both an electrical power loss and a single impact. However, this study also shows a negative correlation between non-zero speedometer readings and vehicles experiencing an electrical power loss and multiple impacts. Eighteen of the twenty-one vehicles had valid pre-crash EDR speeds. Of those eighteen vehicles, the speedometer position and EDR speed were within ±15% for fourteen of the vehicles. The current study also demonstrates that non-zero tachometer readings do not always improve confidence levels of non-zero speedometer readings. While the post-crash needle position may provide a good estimate of the travel speed of the vehicle at the time of power loss, there are numerous other factors which must be considered prior to accepting these readings.
Yannaccone, John R., Kinder, Robert
Travelling Resistance Estimation and Sandy Road Identification for SUVs2018-01-05784/3/2018
The mechanical properties of sandy road are quite different from those of hard surface road. For vehicle control systems such as EMS (engine management system), TCU (transmission control unit) and ABS (antilock brake system), the strategies and parameters set for solid surface road are not optimal for driving on sandy road. It is an effective way to improve the mobility of all-terrain vehicles by identifying sandy road online and shifting the control strategies and parameters of control systems to sandy sets. In this paper, a sandy road identification algorithm for SUVs is proposed. Firstly, the vehicle signals, such as engine torque and speed, gear position, wheel and vehicle speed, are acquired from EMS, TCU and ESP (electronic stability program) through CAN (controller area network) bus respectively. Based on the information and longitudinal force equilibrium equation, the travelling resistance of vehicle is estimated. The hydraulic torque converter is divided into several parts to calculate the acceleration resistance instead of using the rotational inertia coefficient. Then, the sandy road identification algorithm is proposed mainly based on the travelling resistance. Finally, real vehicle tests are carried out on different road conditions. After cone index penetrometer and soil hygrometer are used to measure the sandy test fields, performances of the travelling resistance estimation method and sandy road identification algorithm are validated. The results show that the identification algorithm designed in the paper can identify the sandy terrain effectively.
Wu, Weixiang, Zhang, Jian, Zhao, Jian, Zhu, Bing
Constructing Engine Maps for Full Vehicle Simulation Modeling2018-01-14124/3/2018
The Environmental Protection Agency (EPA) has collected a variety of engine and vehicle test data to assess the effectiveness of new automotive technologies in meeting greenhouse gas (GHG) and criteria emission standards and to monitor their behavior in real world operation. EPA’s Advanced Light-Duty Powertrain and Hybrid Analysis (ALPHA) tool was created to estimate GHG emissions from vehicles using various combinations of advanced technologies and has been refined using data from testing conducted at EPA’s National Vehicle and Fuel Emissions Laboratory. This paper describes a process for constructing complete engine maps using engine dynamometer and in-vehicle test data for use in ALPHA or any other full vehicle simulation which performs similar analyses. The paper reviews how to use available steady state and transient test data to characterize different operating conditions, and then combine the data to construct a complete engine map suitable for ALPHA model simulation. The paper also discusses the use of default values when specific engine test data are unavailable. Finally, tools used to assess the quality of the generated complete engine maps are presented.
Dekraker, Paul, Barba, Daniel, Moskalik, Andrew, Butters, Karla
WHAT WE'RE DRIVING18AUTP02_152/1/2018
It isn't every carmaker that introduces its new model with a session on a tight and slippery test track. But when it's a 1955-kg (4090-lb) sedan with 450 kW (603 hp) and 850 N·m (627 lb·ft) available at the shove of a foot, it is a useful education. That's what Mercedes-Benz offers its U.K. buyers of the new Mercedes-AMG E 63 S 4Matic+.
GKN readies new 2-speed e-axle for 202017AUTP11_1111/1/2017
Driveline-enhancement technology is hot these days, with Tier 1s rolling out new axle-disconnect, electric axle and light-weighting innovations in rapid cadence. In the vanguard of this trend is GKN Driveline, whose masterpiece Twinster dual-clutch differential imparted the 2016 Ford Focus RS and Range Rover Evoque dynamic torque vectoring functions across the entire speed range. That was followed by the company's eTwinster, bringing e-axle technologies pioneered in the Volvo XC90 T8 and other hybrids. Now comes eTwinsterX, which leverages those learnings and integrates a compact 2-speed transmission into a unit aimed at broad vehicle applications-from city cars to plug-in SUVs, high-performance hybrids and EVs and the upcoming wave of electrified light trucks in North America. The system is engineered for front-drive, rear-drive and all-wheel drive configurations and is claimed to be the first e-axle that is fully off-road capable. It can incorporate electric motors from 80 to 120 kW (107 to 161 hp) and peak torque to 147 lb·ft (200 N·m).
Brooke, Lindsay, Adcock, Ian
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
Machine Vision SystemTBMG-273048/1/2017
A number of instruments have been built to obtain range images — a two-dimensional array of numbers that gives the depth of a scene along many directions from a central point in the instrument. Instead of measuring the brightness of many points in a scene, as in a television camera, these instruments measure where each point is in a three-dimensional space. Both range images and the more conventional intensity images from digital cameras have been used in the computer vision research community to determine the pose of observed objects or surface shapes. “Pose” refers to a complete description of an object's position and orientation. For a rigid object, this requires six numbers — such as X, Y, Z, pitch, yaw, and roll — or six equivalent coordinates. The previous methods for pose estimation all suffer from either a lack of generality or from time inefficiency.
Impact of the Future Fuel Economy Targets on Powertrain, Driveline and Vehicle NVH Development2017-01-17776/5/2017
The automotive industry continues to develop new technologies aimed at reducing overall vehicle level fuel consumption. Powertrain and driveline related technologies will play a key role in helping OEM’s meet fleet CO2 reduction targets for 2025 and beyond. Specifically, use of technologies such as downsized engines, idle start-stop systems, aggressive torque converter lock-up schedules, wide-ratio spread transmissions, and electrified propulsion systems are vital towards meeting aggressive fuel economy targets. Judicious combinations of such powertrain and driveline technology packages in conjunction with measures such as the use of low rolling resistance tires and vehicle lightweighting will be required to meet future OEM fleet CO2 targets. Many of the technologies needed for meeting the fuel economy and CO2 targets come with unique NVH challenges. In order to ensure customer acceptance of new vehicles, it is imperative that these NVH challenges be understood and solved. This paper will begin with an introduction of the legislative framework with respect to fuel economy and CO2 targets for light duty vehicles. Key megatrends of engine, transmission, driveline, and electrified propulsion systems will be examined, following which the NVH behavior of each sub-system will be illustrated. A combination of experimentally measured data and simulations will be used to demonstrate key NVH challenges such as high levels of combustion noise, increased driveline torsional excitation, start-stop refinement, shift quality, and high-frequency whine noise from motors/generators in electrified propulsion systems. Examples of component-level and system-level NVH countermeasures will be discussed. Finally, the use of advanced test and simulation-based methodologies for smooth NVH refinement of future propulsion systems will be illustrated using case study examples.
Wellmann, Thomas, Govindswamy, Kiran, Tomazic, Dean
Acceleration Testing of 2016 Freightliner Cascadia with Automated Manual Transmission in Auto Mode2017-01-14263/28/2017
The time/distance relationship for a heavy truck accelerating from a stop is often needed to accurately assess the events leading up to a collision. Several series of tests were conducted to document the low speed acceleration performance of a 2016 Freightliner Cascadia truck tractor equipped with a 12-speed automated manual transmission in Auto Mode. Unlike tests in previous papers, the driver never manually shifted gears. These tests included three trailer load configurations and two different acceleration rates. Data were gathered with both a VBOX and with the Detroit Diesel Diagnostic Link (DDDL) software.
Grimes, Wesley D., Vadnais, Thomas H., Wilcoxson, Gregory A.
Characterizing Factors Influencing SI Engine Transient Fuel Consumption for Vehicle Simulation in ALPHA2017-01-05333/28/2017
The U.S. Environmental Protection Agency’s (EPA’s) Advanced Light-Duty Powertrain and Hybrid Analysis (ALPHA) tool was created to estimate greenhouse gas (GHG) emissions from light-duty vehicles. ALPHA is a physics-based, forward-looking, full vehicle computer simulation capable of analyzing various vehicle types with different powertrain technologies, showing realistic vehicle behavior, and auditing of all energy flows in the model. In preparation for the midterm evaluation (MTE) of the 2017-2025 light-duty GHG emissions rule, ALPHA has been refined and revalidated using newly acquired data from model year 2013-2016 engines and vehicles. The robustness of EPA’s vehicle and engine testing for the MTE coupled with further validation of the ALPHA model has highlighted some areas where additional data can be used to add fidelity to the engine model within ALPHA. A simple model based only on a steady-state fuel map will yield fuel consumption and GHG emissions lower than what is measured during a chassis dynamometer test due to a variety of factors present during transient operation. This paper examines a) typical transient engine operation encountered over the EPA city and highway drive cycles, b) EPA’s vehicle and engine testing to characterize that transient fuel usage, and c) changes made to ALPHA to better model transient engine operation. Topics examined in this paper include spark retardation for powertrain torque management, an engine power rate based fuel adjustment, additional fueling associated with deceleration fuel cut-off, and cylinder deactivation management.
Dekraker, Paul, Stuhldreher, Mark, Kim, Youngki
Development and Challenges of Electrically Selectable One-Way Clutches2017-01-11333/28/2017
This paper discusses new developments in the field of one-way clutches (OWC). These recent developments involve “Selectable OWC (SOWC)” actuating both hydraulically as well as electrically. The primary focus of this paper is a low-current consuming Electrical SOWC (eSOWC) used in hybrid transmission being designed and developed at Ford Motor Company. Other SOWCs currently being utilized across different applications at Ford are also discussed. Clutching devices represent significant cost, weight, size and drag-loss in automatic transmissions. However, implementation of SOWCs offers the potential to reduce transmission cost, size, weight, and spin loss; eSOWCs may also improve shift quality, reduce shift times, improve shift consistency and reduce OWC-related NVH. In Hybrid applications the electric motor(s) and SOWC create a system that is analogous to a manual transmission synchronizer. Similarly, in automatic transmissions SOWC are analogous to pump-solenoid-valve-friction-clutch system. In conclusion, this paper is intended to educate the reader on the development challenges and benefits associated with SOWC using analytical and empirical data.
Bird, Norman J., Bindra, Raunak, Klaser, Jacob
Regenerative Braking Control Development for P2 Parallel Hybrid Electric Vehicles2017-01-11493/28/2017
Regenerative braking in hybrid electric vehicles is an essential feature to achieve the maximum fuel economy benefit of hybridization. During vehicle braking, the regenerative braking recuperates its kinetic energy, otherwise dissipated into heat due to friction brake, into electrical energy to charge the battery. The recuperation is realized by the driven wheels propelling, through the drivetrain, the electric motor as a generator to provide braking while generating electricity. “Rigid” connection between the driven wheels and the motor is critical to regenerative braking; otherwise the motor could drive the input of the transmission to a halt or even rotating in reverse direction, resulting in no hydraulic pressure for transmission controls due to the loss of transmission mechanical oil pump flow. Because of the potential open or slipping torque converter and the multiple step ratios in the drivetrain, and the gear shifting transients in P2 parallel hybrid electric vehicles, special challenges for regenerative braking emerge. The challenges are primarily the torque converter clutch capacity controls, shift scheduling and shift controls, and the coordination between regenerative braking and friction brake controls. This paper describes the control challenges encountered during the regenerative braking development work and presents the design considerations to address these challenges. Finally, the experimental results are presented to demonstrate the performance of the developed regenerative brake controls.
Zhao, Yanan, Kuang, Ming, Nefcy, Bernard, Colvin, Dan, Ford, Stuart, Liu, Zheng
An Advanced Automatic Transmission with Interlocking Dog Clutches: High-Fidelity Modeling, Simulation and Validation2017-01-11413/28/2017
Fuel economy regulations have forced the automotive industry to implement transmissions with an increased number of gears and reduced parasitic losses. The objective of this research is to develop a high fidelity and a computationally efficient model of an automatic transmission, this model should be suitable for controller development purposes. The transmission under investigation features a combination of positive clutches (interlocking dog clutches) and conventional wet clutches. Simulation models for the torque converter, lock-up clutch, transmission gear train, interlocking dog clutches, wet clutches, hydraulic control valves and circuits were developed and integrated with a 1-D vehicle road load model. The integrated powertrain system model was calibrated using measurements from real-world driving conditions. Unknown model parameters, such as clutch pack clearances, compliances, hydraulic orifice diameters and clutch preloads were estimated and calibrated. Simulation results, such as vehicle acceleration, turbine speed, and output shaft speed, are reported and compared with the measured data to validate the transmission model. Subsequently, the transmission model was coupled with internal combustion engine and road load models. This arrangement permitted investigating the dog clutch engagement dynamics under transient conditions. The relative speed of the dog clutch halves was found to be highly sensitive to the transmission input torque, which indicates that a precise engine torque control schemes are necessary for successful engagement.
Alzuwayer, Bashar, Prucka, Robert, Haque, Imtiaz, Venhovens, Paul
Development of New Shift Control System using a Model-based Control Method for Toyota Stepped Automatic Transmissions2017-01-16323/28/2017
A new shift control system using a model-based control method for stepped automatic transmissions. Using a gear train numerical formula model, the model-based shift control system is constructed using minimum calibration parameters with feedforward and feedback controllers. It also adopts control target values for the input shaft revolution and output shaft torque, thus enabling precise control that provides the most suitable shift feeling in various driving situations and for various vehicle characteristics. Furthermore, the model-based shift control system improves robustness in terms of disturbance elements such as production tolerance, time degradation, and use environment. Toyota has adopted this model-based shift control system in its UA80/UB80 8-speed automatic transmissions for front-wheel-drive vehicles and its AGA0 10-speed automatic transmission for rear-wheel-drive vehicles. This paper describes the details of this model-based shift control system.
Tsukamoto, Norihiro, Chimbe, Tomohiro, Asami, Tomohiro, Ota, Keisuke, Masunaga, Seiji
Driveability Improvement with Innovative Toyota 8 Speed Automatic Transmission Control2017-01-11093/28/2017
To meet increasing driveability expectation and government stringent fuel economy regulations reducing CO2 emissions of passenger cars; Toyota developed a new 8-speed automatic transmission "Direct Shift-8AT". Direct Shift-8AT is the first stepped automatic transmission model based on “TNGA” philosophy. New models which received Direct Shift-8AT are the new Camry, Highlander and Sienna. Direct Shift-8AT has an innovative control method with gear train and torque converter models, providing enhanced driveability and fuel economy performance through high efficiency transmission technology. This paper describes details of the new technology and vehicle performance.
Ota, Keisuke, Kondo, Masami, Shinohara, Shuntaro, Tsukamoto, Norihiro, Masunaga, Seiji, Sagawa, Ayumu
Application of Large Eddy Simulation to a Torque Converter to Predict its Fluid Performance2017-01-11163/28/2017
An automatic transmission torque converter is usually used as a power transmission element, which performs the function of the torque matching and the torque amplification of the engine power output. This is referred to as the fluid performance of the torque converter, which is determined by its blade shape. Therefore, it is necessary to predict the fluid performance of the torque converter at the design stage to determine the blade shape, to which computational fluid dynamics (CFD) analysis can be applied. At present, time-averaged turbulence models such as k-ε (called Reynolds-averaged Navier–Stokes—RANS—model) are often used in such CFD analysis for industrial purposes, and are not limited to torque converters because of its appropriate calculation time. However, major traditional RANS models are less reliable for applications to complex three-dimensional flows in the torque-converter than those to simple pipe, channel and boundary layer flows. Therefore, with respect to this issue, a large eddy simulation (LES), which can directly treat the unsteady phenomena of turbulence, has been applied to such complex flow fields not only for research but also for industrial purposes, though it still has a difficulty in the amount of calculation cost. This research applies an open-license software program “FrontFlow/red,” which is specially developed for high-performance computing. This enables the application of the LES turbulence model for a performance prediction of the torque converter design.
Tasaka, Tomohiro, Oshima, Nobuyuki, Fujimoto, Shinji, Kishi, Yuya
Self-Tuning PID Design for Slip Control of Wedge Clutches2017-01-11123/28/2017
The wedge clutch takes advantages of small actuation force/torque, space-saving and energy-saving. However, big challenge arises from the varying self-reinforced ratio due to the varying friction coefficient inevitably affected by temperature and wear. In order to improve the smoothness and synchronization time of the slipping process of the wedge clutch, this paper proposes a self-tuning PID controller based on Lyapunov principle. A new Lyapunov function is developed for the wedge clutch system. Simulation results show that the self-tuning PID obtains much less error than the conventional PID with fixed gains. Moreover, the self-tuning PID is more adaptable to the variation of the friction coefficient for the error is about 1/5 of the conventional PID.
yao, Jian, Chen, Li, Zhao Jr, Ding, Lee, Chunhao, Huang, Ying, Chengliang, Yin
Numerical Investigation of Flow Induced Excitations in a Torque Converter2017-01-11153/28/2017
This study analyzes the flow dynamics of a fluid within an operating torque converter. Transient computational fluid dynamics (CFD) simulations have been carried out with prescribed torque converter motions using commercially available CFD software. The analysis computes torque converter excitation forces that predict flow induced excitations during converter operation. In this study, various torque converter designs are compared and assessed with the aim of limiting flow induced excitations.
Sawkar, Nandan A., Modi, Prashant, Fingerman, Michael
Multibody Dynamics Cosimulation for Vehicle NVH Response Predictions2017-01-10543/28/2017
At various milestones during a vehicle’s development program, different CAE models are created to assess NVH error states of concern. Moreover, these CAE models may be developed in different commercial CAE software packages, each one with its own unique advantages and strengths. Fortunately, due to the wide spread acceptance that the Functional Mock-up Interface (FMI) standard gained in the CAE community over the past few years, many commercial CAE software now support cosimulation in one form or the other. Cosimulation allows performing multi-domain/multi-resolution simulations of the vehicle, thereby combining the advantages of various modeling techniques and software. In this paper, we explore cosimulation of full 3D vehicle model developed in MSC ADAMS with 1D driveline model developed in LMS AMESim. The target application of this work is investigation of vehicle NVH error states associated with both hybridized and non-hybridized powertrains. AMESim is responsible for generating the engine excitation, dampers, and detailed transmission, along with modeling the control strategy for powertrain component operations. Engine block, engine mounts, driveshaft, differential-axle unit, suspension, half-shafts, wheels, and body are modeled in ADAMS and imported as a functional mock-up unit in AMESim. Several key steady-state and transient error states are investigated. In particular, we look at the vibration response at the customer touch points due to transient phenomena generated by engine. Although a specific application of cosimulation is demonstrated in this paper, the methodology is general and can be used to simulate any powertrain system – vehicle combination. Hence data transfer between the co-simulating software is described and effects of key parameters, such as integrator type, time steps, and communication interval, on the quality of results are also investigated.
Khan, Imad M., Datar, Makrand, Sun, Wulong, Festag, Georg, Juang, T Bin, Remisoski, Natalie
New RWD 10 Speed Automatic Transmission for Passenger Vehicles2017-01-10973/28/2017
Aisin AW (AW) and Toyota Motor Corporation (TMC) have developed a new rear wheel drive (RWD) 10-speed automatic transmission, AWR10L65 (TMC name: AGA0), suitable for RWD/AWD luxury passenger cars and sports cars. This 10-speed automatic transmission provides enhanced drivability leading to outstanding driver satisfaction. This has been accomplished using a close ratio gear train with optimized gear steps for rhythmic shift changes and quick acceleration. Low rpm lock-up and highly responsive shift changes result in a direct shift feel. This automatic transmission contributes to improved fuel economy by having higher efficiency and lower mass than current 8-speed RWD automatic transmissions.
Suzuki, Tomohide, Sugiura, Hiroyuki, Niinomi, Atsushi, Maezuka, Shingo, Miyazaki, Terufumi, Habata, Yohei
Honda's new 10-speed is a slick shifter17AUTP02_082/1/2017
Honda's 2018 Odyssey offers room for eight passengers and its all-new transaxle packs 10 forward gears. Developed in-house over a three-year period, the new automatic is the industry's first production 10-speed for front-drive vehicles. It is being produced at the company's Tallapoosa, GA, transmission plant. Automotive Engineering spoke with Tom Sladek, principal engineer at Honda R&D in Raymond, OH, about the new gearbox during the Odyssey's media unveiling at the 2017 Detroit auto show. He said the transaxle's input torque rating is 370 N·m (275 lb·ft) “with some degree of headroom designed in.” While Honda has yet to announce the SAE-rated torque of the Odyssey's 3.5-L V6, it is expected to be greater than the 2017 engine's 250 lb·ft (338 N·m). SAE peak power for the 2018 engine is 280 hp-a 32-hp increase over the current engine's output.
Brooke, Lindsay
Fluid Effects on Shifting Clutch Friction2016-01-220610/17/2016
Good shift quality in automatic transmissions is important for fuel efficiency, driver comfort, and performance. Maintaining this performance over the life of the vehicle is also important. Typically lubricant development focuses on reducing viscosity and friction in order to reduce parasitic losses. In an automatic transmission other factors are also important for good performance, primarily due to the shifting clutches and the torque converter clutch. A high level of friction is desirable for torque capacity and a steady decrease in friction as sliding speed (rpm) decreases is necessary for both good shift feel and good friction system durability over the lifetime of the vehicle. Changes in the friction system over time that result in a lowering of the friction level, particularly at higher sliding speeds, compromise the performance of both types of clutches. In this paper, an experimental shifting clutch durability study demonstrates the impact of changes in friction materials on the mu-v curve and how small changes in a fluid can control these changes.
Williams, Darryl, Guevremont, Jeffrey, Perry, John
Control and Integration Challenges for Future Automatic Transmissions2016-01-11024/5/2016
The ever-increasing regulatory requirement on CO2 emissions drives efficiency improvement of vehicle powertrain systems. In this context, three mega trends have been happening in the automotive transmission industry. First, future automatic transmissions will have more gear steps to offer a broader ratio spread and finer ratio steps, which may enable the engine to operate at its efficient regions more often. Second, engine downsizing with boosted power and flexible cylinder deactivation have been become the technology trend to achieve better thermal efficiency. These engine technologies demand improved transmission dampers with greater isolation capabilities to drive future transmission dampers to be equipped with softer springs. Third, future transmissions will be more efficient due to new architectures and incremental subsystem improvements. We have discovered that all three trends can impose significant challenges to make the future transmission controls and powertrain integration more difficult. This paper starts with a fundamental study on the automotive drivetrain system. The powerful analytical modeling and sensitivity analysis method developed allows us to gain deep understandings of the drivetrain system dynamic nature. The results are general and can help answer some long-standing questions on transmission controls, such as, what is the physics behind the shift vibrations? why are some shifts intrinsically more difficult to control than others? Through the theoretical analysis, we can identify the latent shift vibration tendency and the dynamic structures behind. As the transmission system continue to evolve, it becomes clear that controls and integration will be more challenging for future transmissions. Simple adaption of the control systems from the existing transmissions today may no longer be adequate to the transmission systems tomorrow.
Li, Dongxu
New Slip Ring System for Electromagnetic Coupling in HEV Driveline2016-01-12224/5/2016
This paper describes the slip ring system for a new hybrid system using an electromagnetic torque converter or an electromagnetic coupling. The slip ring system, which enables electric power transmission between a winding rotor and an inverter fixed on a case, is a key component for establishing a new highly efficient hybrid system. Reducing the wear of the brushes in the slip ring system is a major topic of this research. To achieve this objective, brush wear characteristics were investigated using test-piece experiments that simulated the hybrid system environment. By clarifying these characteristics, the structure of a slip ring system for reducing brush wear was identified and a wear prediction method was constructed.
Asami, Shu, Watanabe, Takao, Tominaga, Satoshi, Murakami, Akira
Dynamic Three-Dimensional CFD Simulation of Closed Circuit Torque Converter Systems2016-01-13454/5/2016
This paper details the capability of PumpLinx® and Simerics® in simulating both Steady-State (Multiple Reference Frame) and transient, three dimensional torque converter performance and predicting the coupling point in a closed torque converter system in automatic transmission. The focuses of the simulation are in predicting the performance characteristics of the torque converters at different turbine to impeller rotating speeds (speed ratios) for 7 different torque converter designs and determine the coupling point at 70°C temperature. The computational domain includes the complex 3D design of all the impeller, turbine and reactor blades, the path ways that the oil travels between the above three components and the leakage gaps between these components. The physics captured in the simulation include the turbulence in the flow field and the rigorous treatment of the Fluid Structure Interaction (FSI) for the one-way free wheel reactor in predicting coupling point. The one-dimensional rotating dynamic modeling of the reactor enables the simulation of the whole range of speed ratios starting from 0 to 0.99. The integrated values of the transient torque on all the rotating components are found out to determine the torque ratio, K-Factor and efficiency. The comparisons with the hardware measurements show less than 5% differences between the test and simulation results. The consistency of the numeric schemes used for the simulation combined with the extremely fast run times and close comparisons with the test measurements adds value to the use of PumpLinx as a tool for simulating full torque converter systems.
Srinivasan, Chiranth, Joshi, Darshak, Dhar, Sujan, Wang, De Ming
Design and Calculating of Relay-Type Overrunning Clutch2016-01-11344/5/2016
Overrunning clutches are devices for transmitting rotary motion in one direction only. These mechanisms are widely used in automotive industry, for example, in torque converters, impulse stepless transmissions, inertial continuously variable transmissions, starter engine starting system, and in other similar devices, where torque transmission is performed only in one direction. There are many different designs of the overrunning clutches, for example, ball, roller, cam, ratchet, spring ones, etc. But despite such a variety of designs and great efforts to establish reliable overrunning clutches, these mechanisms are still the weakest parts of many drive systems. Therefore, creation of reliable overrunning clutches is an urgent problem of mechanical engineering. Unfortunately, existing designs of the overrunning clutches have insufficient reliability and durability, which in many cases limits reliability of drive as a whole. The weakest links of the overrunning clutches are the so called wedging elements. This paper describes a promising new design of overrunning clutches. In this design only a small part of torque is transmitted through the weak wedging elements, and the main part of this torque is transmitted through friction disc surfaces, which allows to unload the wedging elements and substantially improve the reliability and durability of the overrunning clutches in comparison with known designs of overrunning clutches. Investigation of the redistribution of amount of torque transmitted through the wedging elements and the friction disc surfaces was done. It was shown that in suggested design there is the principal possibility of reducing of the amount of the torque transmitted through the wedging elements in tens and hundreds times. Besides, a mathematical model describing the dynamics of the overrunning clutches of relay type was developed and investigated in this paper. Feature of the developed model is that, despite of the variability of the structure, dynamics of the overrunning clutches is described by only one system of differential equations, which greatly simplifies the study of periodic solutions and their stability. In this paper there is a methodology how to select the main parameters of relay-type overrunning clutches, which are characterized by considerable load capacity, reliability, and durability.
Aliukov, Sergei, Keller, Andrei, Alyukov, Alexander
Influence of an Automatic Transmission with a Model Predictive Control and an On-Demand Clutch Actuator on Vehicle Fuel Consumption2016-01-11154/5/2016
The demand for lower CO2 emissions requires not just the optimization of every single component but the complete system. For a transmission system, it is important to optimize the transmission hardware as we well as the interaction of powertrain components. For automatic transmission with wide ratio spreads, the main losses are caused by the actuation system, which can be reduced with use of ondemand actuation systems. In this paper, a new on-demand electromechanical actuation system with validation results on a clutch test bench is presented. The electro-mechanical actuator shows an increase in the efficiency of 4.1 % compared to the conventional hydraulic actuation in a simulated NEDC (New European Driving Cycle) cycle. This increase is based on the powerless end positions of the actuator (engaged and disengaged clutch). The thermal tension and wear are compensated with a disk spring. This allows a stable control over service life. This actuation system is developed for a new 7-speed automatic transmission layout and with a model predictive controller the fuel economy and comfort issues are optimized. The decrease in fuel consumption is achieved with an optimized shift strategy depending on the driver type determination. This enables 13 % lower fuel consumption for a small gasoline passenger car (vehicle mass: 1250 kg, air drag coefficient: 0.3, roll resident coefficient: 0.01, total powertrain efficiency NEDC: 20 %) in the NEDC simulation compared to manual shifting defined by legislation. The combination of an on-demand electro-mechanical actuator and a model predictive transmission controller is shown to achieve a fuel consumption reduction of 17.1 % for a small gasoline passenger car.
Huth, Thomas, Pischinger, Stefan
High Efficiency Electromagnetic Torque Converter for Hybrid Electric Vehicles2016-01-11624/5/2016
A new concept of an electromagnetic torque converter for hybrid electric vehicles is proposed. The electromagnetic torque converter, which is an electric system comprised of a set of double rotors and a stator, works as a high-efficiency transmission in the driving conditions of low gear ratio including a vehicle moving-off and as a starting device for an internal combustion engine. Moreover, it can be used for an electric vehicle driving as well as for a regenerative braking. In this concept, a high-efficiency drivetrain system for hybrid electric vehicles is constructed by replacing a fluid-type torque converter with the electromagnetic torque converter in the automatic transmission of a conventional vehicle. In this paper, we present the newly developed electromagnetic torque converter with a compact structure that enables mounting on a vehicle, and we evaluate its transmission efficiency by experiment. Furthermore, using the experimental results and finite element analysis of the electric machine, we clarify the system loss of the electromagnetic torque converter.
Watanabe, Takao, Tsuchiya, Eiji, Ebina, Masaki, Osada, Yasumitsu, Toyama, Tomoyuki, Murakami, Akira
Bond Graph Analysis of Automatic Transmission Shifts including Potential of Extra Clutch Control2016-01-11464/5/2016
New generation of torque converter automatic transmissions (AT) include a large number of gears for improved fuel economy. Control requirements for such transmissions become more demanding, which calls for the development of new shift optimization and analysis tools. This paper presents two contributions to the field of transmission dynamics analysis: (i) bond graph method-based shift transient analysis, and (ii) deriving a unique set of conditions for beneficial use of a third (normally-open) clutch for any upshift or downshift, with emphasis on inertia phase. The derived conditions are examined on an example of 10-speed AT based on the clutch torque input trajectory optimization results. The examination results point out that the extra clutch has a potential of significant performance improvement for any single-transition upshift in the inertia phase, in terms of reduced vehicle jerk RMS value due to the suppressed inertia bump effect. The shift quality improvement is possible in the torque phase, as well, but it is of much smaller extent when compared to that related to the inertia phase.
Ranogajec, Vanja, Deur, Joško, Coric, Mirko
Comparison of Parameter-Identified Simulation Models with Different Detailing Level to Reproduce the Side Shaft Torque of an Automotive Powertrain with Automatic Transmission2016-01-11484/5/2016
The underlying basic model represents a powertrain with automatic transmission including a torque converter. It is based on a greybox-modeling approach, which refers to ordinary differential equations with identified parameters and characteristic curves. The validated basic model is extended in order to reproduce the system behavior and especially the side shaft torque during a gear shift process. Therefore the model is extended by a transmission model with clutches for gear shifting in order to simulate specific powertrain dynamics additionally. The parameters have already been determined for the basic model using a method for isolated and structured parameter identification based on measurement data of an automotive powertrain test bench. A comparable structured parameter identification method is applied to obtain the parameters of the extended model. The extended model will be compared with a state observer which is based on a low-order model and neglects the detailed consideration of submodels with nonlinear characteristics. The observer also reconstructs the side shaft torque during the entire maneuver and will be consulted as an alternative approach for estimating non-measurable states in the system. Comparing the extended model with the observer model will illustrate the limits and potentials of both approaches. The simulation results are compared and evaluated based on the measured side shaft torque. Within this study the extended powertrain model is used as reference model that describes the vehicle dynamics for the considered maneuver precisely, whereas the observer is an alternative approach trying to reach similar results mainly obtained from the measured speed signals.
Yousif, Leonard, Rot, Ivan, Rinderknecht, Stephan
Performance Analysis of Multi-Speed Torque Coupler for Hybrid Electric Vehicle2016-01-11494/5/2016
A novel torque-coupling architecture for hybrid electric vehicles is proposed. The torque-coupling device is based on automated manual transmission (AMT), which is highly efficient and provides six gears for the engine and three gears for each motor to enable the engine and the motors to work at high-efficiency levels in most cases. The proposed power-shift AMT (P-AMT) does not have a hydraulic torque converter and wet clutches, which dampen the driveline shock. Thus, the drivability control of the P-AMT becomes a challenging issue. Accurate engine, motor model and transmission model have been built and the dynamic control of the gear shift process of PAMT in hybrid mode is simulated. The electric motors compensate for the traction loss during the gear shift of the engine. Thus, the engine is allowed to adjust its speed actively by controlling the throttle opening θth and spark advance Δθsp to reach the target synchronous speed in a relatively long time, thereby eliminating the use of a clutch. The simulation results show the P-AMT has good performance in fuel economy and gear-shifting quality.
Yue, Hanqi, Lu, Xintian, Li, Xuesong, Gao, Bingzhao, Chen, Hong
Sliding Mode Adaptive PID Control of an Automotive Clutch-By-Wire Actuator2016-01-91063/14/2016
Dry clutch control is one of the main components of both conventional and advanced automotive powertrain systems. In this paper, a robust control strategy is proposed which is suitable for the precise and accurate control of a clutch-by-wire actuator in automotive applications. A parallel connection of a sliding mode controller to a proportional integral derivative (PID) controller collectively forms the proposed robust controller. The sliding mode controller alone ensures robust control against system nonlinearities by providing a high feedback gain, but it also induces a control chattering phenomenon which could be harmful for the clutch-by-wire actuator. Instead of viewing chattering as an undesirable yet inevitable feature, the chattering signals are used as natural excitation signals for identifying an equivalent PID controller using the recursive least squares algorithm. Analysis is provided on the robustness properties of the control scheme. Simulation results of the proposed controller for a clutch-by-wire actuator are presented using a highly realistic clutch-by-wire system mathematical model. The simulation results demonstrate that the proposed control approach has achieved excellent performance indices while at the same time damp the chattering signal commonly encountered in sliding mode techniques.
Haggag, Salem A.
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