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Viewing 1 to 30 of 2936
2017-03-28
Technical Paper
2017-01-1093
Yosuke Michikoshi, Daisuke Kusamoto, Hirofumi Ota, Masashi Ikemura, Noritaka Takebayashi, Ike Nobukazu, Yasuda Takashi, Inoue Ryohei
Abstract The new eight-speed automatic transmission direct shift-8AT (UA80) is the first automatic transmission to be developed based on the Toyota New Global Architecture (TNGA) design philosophy. Commonizing or optimizing the main components of the UA80 enables compatibility with a wide torque range, including both inline 4-cylinder and V6 engines, while shortening development terms and minimizing investment. Additionally, it has superior packaging performance by optimizing the transmission size and arrangement achieving a low gravity center. It contributes to Vehicle’s attractiveness by improving driving performance and NVH. At the same time, it drastically improves fuel economy and quietness.
2017-03-28
Journal Article
2017-01-1099
Seiji Masunaga, Terufumi Miyazaki, Yohei Habata, Kazuhiko Yamada, Yoshio Hasegawa, Takahiro Kondo, Ichiro Kitaori, Akira Takeichi
Abstract Toyota Motor Corporation has developed an innovative 10-speed longitudinal automatic transmission called the Direct Shift-10AT. The Direct Shift-10AT is a significant contributor to the excellent dynamic performance of the Lexus LC500. A wide gear spread with close gear ratios allows for rhythmical shifting, smooth and powerful acceleration from a standing start, along with quiet and relaxed high- speed driving due to low engine speeds. The lock-up area is expanded to a wider range of vehicle speeds (excluding low-speed regions such as when starting off), by the adoption of a multi-plate lock-up clutch, a newly developed torque converter, and a high-precision controller. As a result, the shift control can match the driver's intended operation more directly because the main cause of the response delay (transient changes in engine speed (flare)) is eliminated. Furthermore, fuel economy is improved due to the adoption of low friction clutches.
2017-03-28
Technical Paper
2017-01-1104
William D. Dunham, Jinwoo Seok, Weitian Chen, Edward Dai, Ilya Kolmanovsky, Anouck Girard
Abstract The efficiency of power transmission through a Van Doorne type Continuously Variable Transmission (CVT) can be improved by allowing a small amount of relative slip between the engine and driveline side pulleys. However, excessive slip must be avoided to prevent transmission wear and damage. To enable fuel economy improvements without compromising drivability, a CVT control system must ensure accurate tracking of the gear ratio set-point while satisfying pointwise-in-time constraints on the slip, enforcing limits on the pulley forces, and counteracting driveline side and engine side disturbances. In this paper, the CVT control problem is approached from the perspective of Model Predictive Control (MPC). To develop an MPC controller, a low order nonlinear model of the CVT is established. This model is linearized at a selected operating point, and the resulting linear model is extended with extra states to ensure zero steady-state error when tracking constant set-points.
2017-03-28
Technical Paper
2017-01-1103
Sergei Aliukov, Andrei Keller, Alexander Alyukov
Abstract The inertial continuously variable transmission is a mechanical transmission which is based on the principle of inertia. This transmission has a lot of advantages, namely: compactness, minimum friction losses and high efficiency as a result of the relatively small number of rotating components, a wide range of transformation of the torque. It does not need any conventional friction clutches. This transmission protects the engine from overload when the output shaft is braked. This drive guarantees optimum conditions of work for the engine regardless of the changing of load, and smoothly changes output speed according to the load. Mostly, design of this transmission consists of a pulsed mechanism with unbalanced inertial units and two overrunning clutches. The objects of the investigation are structural dynamic analysis of the continuously variable transmission. The physical and mathematical models of this transmission are developed.
2017-03-28
Technical Paper
2017-01-1095
Sankar B. Rengarajan, Jayant Sarlashkar, Peter Lobato
Abstract SAE Recommended Practice J1540 [1] specifies test procedures to map transmission efficiency and parasitic losses in a manual transmission. The procedure comprises two parts. The first compares input and output torque over a range of speed to determine efficiency. The second measures parasitic losses at zero input torque over a range of speed. As specified in J1540, efficiency of transmissions is routinely measured on a test-stand under steady torque and speed [2] [3]. While such testing is useful to compare different transmissions, it is unclear whether the “in-use” efficiency of a given transmission is the same as that measured on the stand. A vehicular transmission is usually mated to a reciprocating combustion engine producing significant torque and speed fluctuations at the crankshaft. It is thus a valid question whether the efficiency under such pulsating conditions is the same as that under steady conditions.
2017-03-28
Journal Article
2017-01-1094
Yusuke Nakade, Atsushi Kamada, Koki Ueno, Mikine Kume, Kouji Sakaguchi
Abstract Shift selection devices are desired to be flexible for design and layout, in order to realize the next generation of cockpits for Lexus vehicles. In addition, refined shift operation feelings are also required to be suitable for Lexus vehicles. To meet these demands, the Lexus LC500 has been equipped with a shift-by-wire system, which replaces the mechanical linkage between the shift selector and transmission with electrical signals and an actuator. This shift-by-wire system will be installed in a wide variety of Lexus powertrain lineup, including conventional gas vehicles and hybrid vehicles. Therefore, the next generation shift-by-wire system for Lexus has been developed with high reliability and applicability. This technology will be essential when autonomous driving and autonomous parking systems are realized in the near future.
2017-03-28
Journal Article
2017-01-1097
Tomohide Suzuki, Hiroyuki Sugiura, Atsushi Niinomi, Shingo Maezuka, Terufumi Miyazaki, Yohei Habata
Abstract 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.
2017-03-28
Technical Paper
2017-01-1096
Robin Temporelli, Philippe Micheau, Maxime Boisvert
Abstract Automated Manual Transmission (AMT) based on classic electrohydraulic clutch actuation gives high performances and comfort to a recreational vehicle. However, overall power consumption remains high due to the pump efficiency. In addition, the pump is often driven by the vehicle’s engine and thus is continuously working. To address this issue, a new electrified clutch based on electromechanical actuation has been designed and prototyped. In order to evaluate the effective fuel consumption reduction using this new clutch actuator, a low-cost and agile method is presented and used in this paper. Indeed, instead of integrating the clutch actuator in a real vehicle and performing expensive real emission test cycles on a road, this original method proposes to perform accurate semi-virtual emission test cycles. Moreover, the method allows to perform numerous test iterations in a short time.
2017-03-28
Technical Paper
2017-01-1116
Tomohiro Tasaka, Nobuyuki Oshima, Shinji Fujimoto, Yuya Kishi
Abstract 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.
2017-03-28
Journal Article
2017-01-1120
Kenji Tsutsumi, Yoshitaka Miura, Yusuke Kageyama, Arata Miyauchi
Abstract A CVT variator chain system is superior in transmission efficiency to a belt system because of its lower internal friction. However, a chain produces more noise than a belt due to the long pitch length of contact between the pulleys and rocker pins. This study focuses on optimization of the pitch sequence for reducing chain noise. The previous pitch sequence was suitably combined of links of different lengths to improve noise dispersibility for reducing chain noise. First, the object function was defined as the reduction of the peak level of 1st-order chain noise combined with a well-balanced the levels on the low and high frequency sides. Interior background noise consisting of road noise and wind noise have the characteristic that they increase as the frequency decreases.
2017-03-28
Technical Paper
2017-01-1119
Fangwu Ma, Ying Zhao, Yongfeng Pu, Jiawei Wang
Abstract Gear transmission is widely used in mechanical transmission system and acts an important role in automotive industry. Manufacturing errors, assembly looseness, gear wear issues may result in gear backlash, noise and fatigue damage seriously affecting efficiency and service life of gear transmission. For gear transmission assembled, it is important to monitor the conditions of gear meshing and prevent the occurrence of dangerous situations. How to define the issues of gear tooth wear, misaligned bearing, gear eccentricity, backlash, and how to find faulty planetary gear sets and specific issues existing in gear transmission are meaningful and significant to ensure the quality of product. This paper starts from the analysis on gearing mechanism. Based on the behaviors represented by the issues, gear tooth wear, misaligned bearing, gear eccentricity and backlash are demonstrated and explained in detail.
2017-03-28
Technical Paper
2017-01-1108
Yulong Lei, Yao Fu, Ke Liu, Li Xingzhong, Zhenjie Liu, Yin Zhang, Xuanyi Fu
Abstract Selection of gearshift point plays an important role in the field of automatic transmission technology, which directly affects the vehicle dynamic and economic performance, etc. In order to designing optimal gearshift strategies for conventional passenger vehicles equipped with stepped automatic transmission, in this paper, the vehicle power demand was defined under different environment, different driving intention and different vehicle operating conditions. Dynamic programming (DP) method is used to solve the optimal static gearshift decision sequence based on the simplified model of powertrain system. The drivability is respected by imposing an inequality constraint on the power reserve limit and the fuel economy is the objective function. Considering the change of vehicle additional load and road slope, the gearshift strategy based on power reserve is proposed.
2017-03-28
Technical Paper
2017-01-1105
Sergei Aliukov, Alexander Alyukov
Abstract The inertial continuously variable transmissions are mechanical transmissions that are based on the principle of inertia. These transmissions have a lot of advantages. Usually, the design of the inertial continuously variable transmissions consists of inertia pulsed mechanism with unbalanced inertial elements and two overrunning clutches. Dynamics of the transmissions is described by systems of substantial nonlinear differential equations. In general, precise methods of solution for such equations do not exist. Therefore, in practice, approximate analytical and numerical methods must be employed. The main analytical methods employ successive approximation, a small parameter, or power series expansion. Each approach has its advantages and disadvantages. Therefore, we need to compare them in order to select the best method for dynamic study of such kind of transmissions.
2017-03-28
Technical Paper
2017-01-1110
Muammer Yolga, Markus Bachinger
Abstract With the introduction of new regulations on emissions, fuel efficiency, driving cycles, etc. challenges for the powertrains are significantly increasing. In order to fulfil these regulations, hybrid-electric powertrains are an unquestioned option for short and long-term solutions. Hybridization however, is not only fulfilling these challenging efficiency or emission targets, but also allows numerous new possibilities on control strategies of different powertrain elements as well as new approaches of designing them. A good example is transmissions where, hybridization allows a new transmission type called Dedicated Hybrid Transmission (DHT), which enables to use novel control strategies bringing improved performance, driveability, durability and NVH behavior. This paper focuses on the novel shift strategy where friction clutches do not have to slip.
2017-03-28
Journal Article
2017-01-1111
Marcello Canova, Cristian Rostiti, Luca D'Avico, Stephanie Stockar, Gang Chen, Michael Prucka, Hussein Dourra
Abstract To improve torque management algorithms for drivability, the powertrain controller must be able to compensate for the nonlinear dynamics of the driveline. In particular, the presence of backlash in the transmission and drive shafts excites sharp torque fluctuations during tip-in or tip-out transients, leading to a deterioration of the vehicle drivability and NVH. This paper proposes a model-based estimator that predicts the wheel torque in an automotive drivetrain, accounting for the effects of backlash and drive shaft flexibility. The starting point of this work is a control-oriented model of the transmission and vehicle drivetrain dynamics that predicts the wheel torque during tip-in and tip-out transients at fixed gear. The estimator is based upon a switching structure that combines a Kalman Filter and an open-loop prediction based on the developed model.
2017-03-28
Technical Paper
2017-01-0890
Yoichiro Nakamura, Masahisa Horikoshi, Yasunori TAKEI, Takahiro Onishi, Yasuhiro Murakami, Chip Hewette
Abstract Heavy duty vehicles take a large role in providing global logistics. It is required to have both high durability and reduced CO2 from the viewpoint of global environment conservation. Therefore lubricating oils for transmission and axle/differential gear box are required to have excellent protection and longer drain intervals. However, it is also necessary that the gear oil maintain suitable friction performance for the synchronizers of the transmission. Even with such good performance, both transmission and axle/differential gear box lubricants must balance cost and performance, in particular in the Asian market. The development of gear oil additives for high reliability gear oil must consider the available base oils in various regions as the additive is a global product. In many cases general long drain gear oils for heavy duty vehicles use the group III or IV base oils, but it is desirable to use the group I/II base oils in terms of cost and availability.
2017-03-28
Journal Article
2017-01-1133
Norman J. Bird, Raunak Bindra, Jacob Klaser
Abstract 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.
2017-03-28
Technical Paper
2017-01-1134
Taechung Kim, Jaret Villarreal, Luke Rippelmeyer
Abstract Automotive automatic transmissions have multiple axis configurations in which planetary gears transmit torque to a counter gear on another axis. Although general characteristics of a planetary gear (component level) have been studied, no specific investigations are available in literature explaining interactions between planetary and torque-transmitting gears (Full Unit or Sub-System). In this paper, a system FEA model (Using TM3D) of a Ravigneaux and a counter gear pair is introduced, exploring influences of system deflection in pinion load sharing to changes in gear root stress pattern. Additionally, by a series of strain gauge tests under a controlled test jig, reliability of the FEA model is verified. Finally, benefits of system-level FEA are explained by macro/micro-geometry optimization in the early design stage.
2017-03-28
Technical Paper
2017-01-1131
Keith Gilbert, Srini Mandadapu, Christopher Cindric
Abstract The implementation of electronic shifters (e-shifter) for automatic transmissions in vehicles has created many new opportunities for the customer facing transmission interface and in-vehicle packaging. E-shifters have become popular in recent years as their smaller physical size leads to packaging advantages, they reduce the mass of the automatic transmission shift system, they are easier to install during vehicle assembly, and act as an enabler for autonomous driving. A button-style e-shifter has the ability to create a unique customer interface to the automatic transmission, as it is very different from the conventional column lever or linear console shifter. In addition to this, a button-style e-shifter can free the center console of valuable package space for other customer-facing functions, such as storage bins and Human-Machine Interface controllers.
2017-03-28
Technical Paper
2017-01-1137
Xiaofeng Yin, Han Lu, Xiaohua Wu, Yongtong Zhang, Wei Luo
Abstract For the vehicle equipped with stepped automatic transmission (SAT) that has a fixed number of gears, gearshift schedule is crucial to improve the comprehensive performance that takes into account power performance, fuel economy, and driver’s performance expectation together. To optimize and individualize the gearshift schedule, an optimization method and an improved performance evaluation approach for multi-performance gearshift schedule were proposed, which are effective in terms of reflecting the driver's expectation on different performance. However, the proposed optimization method does not consider the influence of the road slope on the comprehensive performance. As the road slope changes the load of vehicle that is different from the load when a vehicle runs on a level road, the optimized gearshift schedule without considering road slope is obviously not the optimal solution for a vehicle equipped with SAT when it runs on ramp.
2017-03-28
Journal Article
2017-01-1138
Gary Stevens, Martin Murtagh, Robert Kee, Juliana Early, Roy Douglas, Robert Best
Abstract In this paper a dynamic, modular, 1-D vehicle model architecture is presented which seeks to enhance modelling flexibility and can be rapidly adapted to new vehicle concepts, including hybrid configurations. Interdependencies between model sub-systems are minimized. Each subsystem of the vehicle model follows a standardized signal architecture allowing subsystems to be developed, tested and validated separately from the main model and easily reintegrated. Standard dynamic equations are used to calculate the rotational speed of the desired driveline component within each subsystem i.e. dynamic calculations are carried out with respect to the component of interest. Sample simulations are presented for isolated and integrated components to demonstrate flexibility. Two vehicle test cases are presented.
2017-03-28
Journal Article
2017-01-1135
Sen Zhou, Bryan Williams
Abstract Transmission spin loss has significant influence on the vehicle fuel economy. Transmission output chain may contribute up to 10~15% of the total spin loss. However, the chain spin loss information is not well documented. An experimental study was carried out with several transmission output chains and simulated transmission environment in a testing box. The studies build the bases for the chain spin loss modeling and depicted the influences of the speed, the sprocket sizes, the oil levels, the viscosity, the temperatures and the baffle. The kriging method was employed for the parameter sensitivity study. A closed form of empirical model was developed. Good correlation was achieved.
2017-03-28
Journal Article
2017-01-1124
Enrico Galvagno, Pablo Gutierrez, Mauro Velardocchia, Alessandro Vigliani
Abstract This paper investigates the effect of the powertrain mounting system on the linear and nonlinear torsional dynamical behaviour of a transmission system. To this aim, two dynamic models, one with rigid mounts and the other with flexible mounts, are presented and compared: the first model considers only the torsional dynamics of transmission and driveline, while the second model includes also a 3 degrees-of-freedom powertrain block. The mechanical coupling and interaction between the powertrain block and transmission system is discussed and formulated. These models are then analyzed in terms of vibrational mode shapes, natural frequencies and Frequency Response Functions (FRFs); a sensitivity analysis of the main transmission parameters, e.g. the gear ratio, is also presented.
2017-03-28
Technical Paper
2017-01-1129
Kayoko Kanda
Abstract The frictional performance of the wet clutch used for automatic transmission is determined by the interaction between the paper-based friction material (D/C), separator plates (S/P), and automatic transmission fluid (ATF). In order to understand the impact of additives in ATF on the frictional performance, commercial ATF was modified by adding 5 types of additives one by one in a specified concentration, and the friction test was conducted for 6 levels of ATF consisting of these 5 modified ATFs plus commercial ATF.
2017-03-28
Journal Article
2017-01-1127
Pengchuan Wang, Nikolaos Katopodes, Yuji Fujii
Abstract Wet clutch packs are widely used in today’s automatic transmission systems for gear-ratio shifting. The frictional interfaces between the clutch plates are continuously lubricated with transmission fluid for both thermal and friction management. The open clutch packs shear transmission fluid across the rotating plates, contributing to measurable energy losses. A typical multi-speed transmission includes as many as 5 clutch packs. Of those, two to three clutches are open at any time during a typical drive cycle, presenting an opportunity for fuel economy gain. However, reducing open clutch drag is very challenging, while meeting cooling requirements and shift quality targets. In practice, clutch design adjustment is performed through trial-and-error evaluation of hardware on a test bench. The use of analytical methodologies is limited for optimizing clutch design features due to the complexity of fluid-structure interactions under rotating conditions.
2017-03-28
Technical Paper
2017-01-1128
Yuvraj Y. Gorwade, Anand S. Damami
Abstract To ensure a robust, reliable and durable product, predicting the useful life of aggregates at the concept stage is a very important aspect in the any product design. This requirement is very much necessary in today’s competitive environment, wherein the customer expectations are increasing and development time for reliable product is shrinking. Clutch is one of the important aggregate in an automobile having manual transmission. It acts like a fuse in the driveline system wherein its wear and tear cannot be avoidable. The performance of Clutch is correlated with its useful life. In this paper, a unique methodology is formulated for the prediction of beta life of clutch. Actual field data of over 3 to 4 years related with warranty claims, mode of failures, usage kilometers etc. has been collected on a typical utility vehicle platform which has been operating on roads of Indian subcontinent.
2017-03-28
Technical Paper
2017-01-1140
Yang Xu, Yuji Fujii, Edward Dai, James McCallum, Gregory Pietron, Guang Wu, Hong Jiang
Abstract A transmission system model is developed at various complexities in order to capture the transient behaviors in drivability and fuel economy simulations. A large number of model parameters bring more degree of freedom to correlate with vehicular test data. However, in practice, it requires extensive time and effort to tune the parameters to satisfy the model performance requirements. Among the transmission model, a hydraulic clutch actuator plays a critical role in transient shift simulations. It is particularly difficult to tune the actuator model when it is over-parameterized. Therefore, it is of great importance to develop a hydraulic actuator model that is easy to adjust while retaining sufficient complexity for replicating realistic transient behaviors. This paper describes a systematic approach for reducing the hydraulic actuator model into a piecewise 1st order representation based on piston movement.
2017-03-28
Technical Paper
2017-01-1139
Syeda Faria Mahmud, Shahjada Pahlovy, Masamitsu Kubota, Makoto Ogawa, Norio Takakura
Abstract Reduction of drag torque is a crucial demand for improvement of transmission efficiency and fuel economy. In the low speed range, the drag torque at first increases with speed until it reaches a peak point, and then it starts decreasing sharply and finally stays at a minimum level until certain speed limit. Several analytical and simulation models have been presented by the researchers describing the drag torque characteristics at lower clutch speed. However, under certain conditions, the drag torque again starts to rise sharply in the high speed range (6000~10000+ rpm) and even exceeds the peak torque magnitude of low speed. The alarming jump of the drag torque at high rotational speed remains indeterminate to date. In this paper, we presented a simulation model that can predict the high speed torque jump up at different conditions. Simulation result shows that the static pressure decreases very sharply in the oil outlet region as the speed rises beyond 5000 rpm.
2017-03-28
Journal Article
2017-01-1142
Vanja Ranogajec, Josko Deur
Abstract The ever-present pressure on shortening the development cycle of transmission systems requires development of numerical methods and tools that would speed up those processes. This paper contributes to the field by proposing a method for automated generation of the full-order automatic transmission (AT) model from a bond graph model that directly reflects the AT structure. The proposed numerical method is implemented within the 20-sim and MATLAB software environments, where 20-sim is used to draw the bond graph and export it to a MATLAB script (or simulate it). A proposed method relies on a system identification method that extracts the characteristic full-order model state-space matrices from either a 20-sim-Matlab exported script or 20-sim-simulated bond graph model. The automated modeling method is demonstrated on an example of an advanced 10-speed AT.
2017-03-28
Journal Article
2017-01-1144
Jongryeol Jeong, Ram Vijayagopal, Aymeric Rousseau
Abstract Building a vehicle model with sufficient accuracy for fuel economy analysis is a time-consuming process, even with the modern-day simulation tools. Obtaining the right kind of data for modeling a vehicle can itself be challenging, given that while OEMs advertise the power and torque capability of their engines, the efficiency data for the components or the control algorithms are not usually made available for independent verification. The U.S. Department of Energy (DOE) funds the testing of vehicles at Argonne National Laboratory, and the test data are publicly available. Argonne is also the premier DOE laboratory for the modeling and simulation of vehicles. By combining the resources and expertise with available data, a process has been created to automatically develop a model for any conventional vehicle that is tested at Argonne.
Viewing 1 to 30 of 2936