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Viewing 1 to 30 of 2732
2015-04-14
Technical Paper
2015-01-1132
Jiaxing Zhan, Mohammad Fard
Preventing the backdriving and controlling the position stability of gearbox are critical tasks in some precision machineries and instruments. Consequently, many self-locking mechanisms have been developed to stabilize the rotation accuracy in gearing system. However, these assistant devices could enlarge the volume of gearbox, increase the complexity of transmission system and introduce more errors between gear pairs. Therefore, alternative methods are required to achieve design requirement without adding any extra electric or mechanical device. As a novel gear designed with anti-backdriving capacity, the self-locking gear has been of great interest to researchers and engineers to date. The self-locking gear can be used to prevent either the inertia driving, or backdriving, or both, when the driving torque is suddenly reduced as a result of power off, torsional vibration, power outage, or any mechanical failure at the transmission input side.
2015-04-14
Technical Paper
2015-01-1130
Sergei Aliukov, Andrei Keller, Alexander Alyukov
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.
2015-04-14
Technical Paper
2015-01-1123
Jiangwu Zhang, Donghao Liu, Haisheng Yu
Torsional vibrations of the full hybrid electric vehicle driveline with a novel single-mode power-split transmission are investigated, in which three power sources, internal combustion engine (ICE), motor/generator 1 (MG1) and motor/generator 2 (MG2) are equipped. The compound planetary gear unit inside the transmission provides the driveline output with continuously variable gear ratios and serves as a power splitting device. Though very similar in configuration, the compound planetary gear used herein is a novel variation of Ravigneaux planetary gear set. MG1, MG2 and ICE are connected to the small sun gear (S1), the large sun gear (S2), the planetary carrier (C), respectively. The ring gear (R) is connected to the final reduction gear (FR), outputting tractions by the conventional differential (DF) to the right and left half shafts for the front wheels.
2015-04-14
Technical Paper
2015-01-1102
Katsuhiko Ohishi, Toshihiro Uehara, Ichirou Kishigami
In recent years, fuel economy improvement of automobiles is required to reduce emissions of carbon dioxide (CO2) which is a greenhouse gas and is well known as one of the factors of global warming. Therefore, continuously variable transmissions (CVT) have been used increasingly, because they are light, compact and contribute to better fuel consumption. Metal belt CVTs are the most popular system in use today. 18mass%Ni maraging steel is used for CVT belts because it has good weldability, good formability and high fatigue strength. Maraging steels strengthened by Ti have high fatigue strength, but TiN particles, which are the main non-metalic inclusions inside steels, might cause fatigue cracks in high cycle regions over 107 cycles. At present there is a special melting process to minimize TiN particle size, but we need further technological innovations to improve fatigue strength.
2015-04-14
Technical Paper
2015-01-1108
Hongqing Chu, Yong Chen, Lishu Guo, Bingzhao Gao, Hong Chen
Automated Manual Transmission is popularly used in microcars due to its small size, light weight, low cost and high efficiency. The dry clutch engagement is a very important control issue for AMT vehicles. The performance of dry clutch engagement must be guaranteed with the following different and sometimes conflicted goals: the shortest possible lock up time, the smoothest possible lock up process and the smallest friction losses during the slipping phase. A precondition for this complicated control issue is to obtain the information of road slope during the process of hill-start. The rapid development of sensing technology makes many semiconductor companies produced various kinds of MEMS (Micro-Electro-Mechanic System) sensors. Slope sensor is already applied in some ESP (Electronic Stability Program) vehicles which equipped with hill parking aid system.
2015-04-14
Technical Paper
2015-01-1101
Jun Hakamagi, Tetsuya Kono, Ryoji Habuchi, Naoki Nishimura, Masahiro Tawara, Naoki Tamura
As requirements for protecting the global environment are being heightened on a worldwide scale in recent years, the development of fuel-economy technologies in order to reduce CO2 emissions is an important issue for the automotive industry. Aiming of improving fuel economy, TOYOTA has developed a new belt-type continuously variable transmission (CVT), unit K114, for 2.0-liter class vehicles. The CVT has adopted various technologies fuel economy such as a coaxial 2-discharge port oil pump system, wider ratio coverage, flex lock-up control,and so on. Notably, a start-stop system, which makes the engine stop automatically while the vehicle stopping with “D” range to reduce wasting the energy, is compatible with the CVT with higher quality and lower cost. In addition, the CVT has been also worked on improving quietness by adopting new soundproofing cover and by revising the arrangement of the steel belt elements in order to reduce the vibrator force which generates the belt noise.
2015-04-14
Technical Paper
2015-01-1127
Wenbin Liu, Gangfeng Tan, Xiaoqing Tian, Zhiqiang Hu, Yuanqi Gao, Zhi Li, Junyi Yuan, Wei Liu
As a kind of an important auxiliary brake of heavy vehicle, hydraulic retarder has good performance for stability and braking sustainability. However, the hydraulic retarder is filled with air when the vehicle is traveling in non-braking state, and the Air-friction may reduce the vehicle transmission efficiency obviously.   The air density in retarder cavity can be decreased by pumping the gas, which can reduce the transmission power loss. The gas pumping in retarder cavity has an important influence on the retarder working stability. Firstly, the dynamic characteristics relationships between the vacuum degree and the change of flow resistance in retarder cavity are analyzed by the 3D fluid simulation in different driving conditions, and the stability boundary conditions of the Air-friction change is determined.
2015-04-14
Technical Paper
2015-01-0228
Francesco Braghin, Francesco Salis
An innovative low cost active gear-shift and clutch for Formula Student cars is designed and produced. Racecars require extremely quick gear-shifts and every system to be as light as possible. The proposed solution has been designed to reduce energy consumption, weight and improve gear-shift precision compared to an electro-hydraulic solution although keeping state of the art performances. This could be easily obtained with DC electric motors, System modeling, regulator design, based on PI-control, and simulation were carried out. Electronics, both signal and power, micro-controller based design and program coding, written in C language, were the next steps. Data from the working system mounted on the car were acquired, in order to verify the validity of the design choices. The solution has proven to satisfy the requirements with 20 ms shifting time and reduced weight (2 kg), energy consumption and system complexity.
2015-04-14
Technical Paper
2015-01-1120
Siddhartha Singh, Sudha Ramaswamy
Driving comfort is very important selling factor in today’s automobile market. Manual Transmission Clutch systems has to balance between driving control given to the driver and driver comfort.If ergonomics of ABC pedals are not taken care, driving stress will increase. The increase in engine torque because of change in technologies like turbocharging and pressure injection has also increased the release load for actuating clutch which in turn increases pedal load. There are many assistance mechanisms integrated with pedal to reduce the load like over-center spring, double torsion spring, each with its own limitations.
2015-04-14
Technical Paper
2015-01-1109
Yulong Lei, Ke Liu, Yao Fu, Ge Lin, Bin Song
This investigation presents a methodology to develop and optimize shift process control strategy to improve shift quality as perceived by drivers during power-on upshift events for Dual Cultch Transmission (DCT) vehicles. As part of the first study, the main factors affecting shift quality during shifting process under typical working conditions are analyzed. And taking the power-on upshift as example, dynamic model of DCT shifting process is build. An Integrated control strategy is proposed for power on upshift, which during torque phase slipping revolving speed controller is adapted to harmonically control two clutches power switching process, and during Inertial phase engine torque is regulated to synchronize with target gear while holding the oncoming clutch pressure. Oncoming oil pressure gradient in torque phase and engine torque reducing target quantity in inertial phase are chosen as controlled quantity.
2015-04-14
Technical Paper
2015-01-0517
Masaaki Kawahara, Noriaki Katori, Tatsuya Koyama
Reduction of fatigue and improvement of drivability have been required in commercial vehicles and automated manual transmissions are widely used. Further reduction of shifting time results in faster collision and slide between chamfers of sleeve and dog gear, and wear of chamfers increases. In this study, mechanism of the wear was clarified and a machine to evaluate the wear by test piece Base was developed. Using this machine, materials to improve the wear resistance were developed. It was found that addition of B and Ti-Nb had significant effect in the improvement of wear resistance. The developed material showed 45 % reduction in wear in transmission durability test.
2015-04-14
Technical Paper
2015-01-1113
Jae Sung Bang, Young-Kwan Ko, Tae-Hee Jung
In this paper, we consider the driveline oscillation problem for electric vehicles. The research is motivated by the fact that the driveline oscillation should be eliminated because the oscillation has a bad effect on the ride comfort of the electric vehicles. In contrast with the conventional vehicle which contains a torque converter at the automatic transmission, the driveline of the electric vehicles is the lightly damped system since the torque source, that is, the motor is directly connected to the driving wheel through the driveline. As a result, the magnitude of the oscillation of the electric vehicle is much bigger than that of the conventional vehicle and the residual oscillation lasts for long time. To solve the problem, we suggest the novel active damping control algorithm using the speed of the driving wheel which is directly connected to the motor.
2015-04-14
Technical Paper
2015-01-1104
Patrick Sexton, Robert A. Smithson, Gordon McIndoe
In order to introduce Dana’s Variglide Continuously Variable Planetary (CVP) technology to the mobility industry, Dana has produced demonstrator transmissions for use in a rear wheel drive C-class car and in a fork lift truck. The intention is to illustrate how the CVP can be combined with conventional transmission technology to produce either a continuously variable transmission with the ratio range comparable to that of the latest step ratio transmissions, or used in a simple IVT configuration for off-highway applications. The co-axial design of the CVP allows it to package well into current drivetrain solutions. The ratio control of the device is fast, precise, and stable and the CVP does not require high power consumption for clamping. Multiple power flow configurations of the CVP are shown to blend well with current conventional transmission technology as well as future hybrid configurations.
2015-04-14
Technical Paper
2015-01-1303
Wenli Li, Xiao-Hui Shi, Dong Guo, Peng Yi
An approach using dynamic emulation of mechanical loads for testing and validation of the vehicles' Transmission will be presented in the paper. In order to reduce costs and shorten new vehicle development cycle time, vehicle simulation on the driveline test bench is an attractive alternative at the development phase to reduce the quantity of proto vehicles. This test method moves the test site from the road to the bench without the need for real chassis parts. Dynamic emulation of mechanical loads is a Hardware-in-the-loop (HIL) procedure, which can be used as a supplement of the conventional simulations in testing of the operation of algorithms without the need for the prototypes. The combustion engine is replaced by a electric drive dynamometer, which replicates the torque and speed signature of an actual engine, The road load sistance of the vehicle on a real test road is accurately simulated on Load dynamometer by corrected road load forces.
2015-04-14
Technical Paper
2015-01-1124
Gerrit Knabe, Markus Zahlten, Ferit Kücükay
In order to improve the acoustic comfort inside passenger cars in terms of transmission noise, a special method has been developed. For a structured and comprehensive analysis of the transmission noise, the generation and transfer mechanisms are divided into four separate but nevertheless connected parts. Although simulation and components tests are used to analyze vibration excitation which may cause rattle and the mechanisms causing rattle in detail, they are not the main part of the analysis. The focus of this study is on the transfer of automotive transmission rattle and the passengers’ perception. The noise characteristics, which can be specified using conventional analysis methods as well as assessments by test persons, are important for the transfer path of the disturbing noise. By combining different methods of transfer path analysis (TPA), direct airborne-sound transmission is identified as a significant transfer path of the rattling noise.
2015-04-14
Journal Article
2015-01-1093
Kirby S. Clark, Tejinder Singh, Ronald P. Buffa, Jack M. Gayney, William L. Cousins, Zhe Xie, Steven P. Moorman, Alexandria Wilson, Michael P. Fannin, Mark L. Graham, Christopher B. Preston, Michael B. Solt, David J. Varda, Mark R. Gilmore, Martin G. Foulkes, Rebecca K. Risko
General Motors has introduced a new front wheel drive seven speed dry dual clutch automatic transmission in 2014. The 250 Nm input torque rated gear box was designed and engineered for a global market in both front wheel drive and all-wheel drive configurations. The transmission has integrated start/stop capability enabled by the use of an electric motor driven pump and a pressurized accumulator. The architecture selected was chosen for optimization of packaging, fuel economy, mass, shift optimization, and NVH. High mileage durability and world class drivability were the cornerstone deliverables during the engineering and design process Fuel efficiency is estimated to be 3%+ improvement over a conventional 6 speed automatic transmission. FWD variant mass of 78.1 kg was achieved through the rigorous engineering processes used to optimize the transmission system.
2015-04-14
Technical Paper
2015-01-1148
Xi Li, Weiguo Zhang, Jinning Li, Ming Jiang, Yunqing Zhang
A simulation model of a single cone synchronizer is presented using the dynamic implicit algorithm with commercial Finite Element Analysis (FEA) software Abaqus.. The meshing components include sleeve gear, blocking ring, clutch gear and detent, which are all considered as deformation body. The processes mainly contain the contact between sleeve teeth and blocking teeth, meshing period and the impact of sleeve teeth and clutch gear teeth,and these nonlinear contact steps are realized with Abaqus. In addition, a shift force as the driving load derives from a synchronizer experiment for approximating to the true condition, and a moment is added to the clutch gear to realize the relative rotational speed. Based on the FEA model, the effects of the varied cone angle and the frictional coefficients between the cone surfaces of blocking ring and clutch gear on the synchronizer time and contact stress are discussed.
2015-04-14
Technical Paper
2015-01-1149
Donghao Liu, Haisheng Yu, Jiangwu Zhang
Nowadays environmental pollutions and energy efficiency are two of the major challenges for the automotive industry arisen from the increasingly stringent environmental standard. Over the last few years, Hybrid Electric Vehicles (HEVs) have been developed as the most promising solutions that can have the advantages both of the conventional vehicles and electric vehicles. The power-split hybrid powertrain has become the main stream of hybrid electric vehicles in the world market. Toyota hybrid system (THS) is a single mode power-split transmission, which has the advantages for the mechanical configure and control strategy. However, at high vehicle speeds, the speed of the driving motor is quite high, so that the efficiency of the driving motor is poor. General Motors (GM) two-mode hybrid system has two power-split modes and four fixed speed ratio transmissions with different combinations of the clutches to realize cost savings and reduce demand on the motor torque and speed.
2015-04-14
Technical Paper
2015-01-1153
Kingsly Samuel, David Brigham, Mark Jennings
The Powersplit transaxle is a key subsystem of Ford Motor Company’s hybrid electric vehicle line up. The powersplit transaxle consists of a planetary gear, four reduction gears and various types of bearings. During vehicle operation, the transaxle is continuously lubricated by a lube oil pump. All these components consume power to operate and they contribute to the total transaxle losses which ultimately influences energy usage and fuel economy. In order to enable further model-based development and optimization of the transaxle design relative to vehicle energy usage it is essential to establish a physics-based transaxle model with losses distributed across components, including gears, bearings etc. In this work, such a model has been developed. The model accounts for individual bearing losses (speed, torque and temperature dependency), gear mesh losses, lube pump loss and oil churning loss.
2015-04-14
Technical Paper
2015-01-0380
Stefania Falfari, Gian Marco Bianchi, Giulio Cazzoli, Federico Brusiani, Claudio Forte, Cristian Catellani
In PFI and GDI engines the tumble motion is the most important charge motion for enhancing the in-cylinder turbulence level at ignition time close to the spark plug position. In the open literature different studies were reported on the tumble motion, experimental and not. Research on the tumble motion generation at partial load conditions is rather infrequent. In the present paper the research activity on the tumble generation at partial load and very partial load conditions was presented. The added value of the analysis was the study of the effect of the throttle valve rotational direction on the tumble motion and the final level of turbulence at the ignition time close to the spark plug location. The focus was to determine if the throttle rotational direction was crucial for the tumble ratio and the turbulence level. The analyzed engine was a PFI 4-valves motorcycle engine. The engine geometry was formed by the intake duct and the cylinder. The CFD code was FIRE AVL code 2013.1.
2015-04-14
Technical Paper
2015-01-0212
Mohamed El Morsy, Gabriela Achtenova
Condition monitoring is used to increase machinery availability and machinery performance, whilst reducing consequential damage, increasing machine life, reducing spare parts inventories, and reducing breakdown maintenance. An efficient condition monitoring system provides early warning of faults by predicting them at an early stage. When a localized fault occurs in gears, the vibration signals always exhibit non-stationary behavior. The periodic impulsive feature of the vibration signal appears in the time domain and the corresponding gear mesh frequency (GMF) emerges in the frequency domain. However, one limitation of frequency-domain analysis is its inability to handle non-stationary waveform signals, which are very common when machinery faults occur. Particularly at the early stage of gear failure, the GMF contains very little energy and is often overwhelmed by noise and higher-level macro-structural vibrations.
2015-04-14
Technical Paper
2015-01-1625
Frederic Boissinot, Jerome Bellavoine, Andrew Shabashevich, Siegfried Puster
In today’s competitive automotive market, car manufacturers and transmission suppliers are challenged with an increasing number of powertrain variants and complexity of controls software. They are facing internal pressure to provide mature and refined calibrations earlier and earlier in the development process. Until now, it has been difficult to respond to these requests as the calibration tasks linked to drivability are still mostly done in vehicles. This paper describes a new methodology designed to answer these challenges by performing automated shift quality calibration for transmissions prior to the availability of test vehicles. This procedure allows development of accurate and representative transmission calibrations focused on drivability by using a powertrain dynamometer coupled with a real-time vehicle dynamics model. By using a Power Train Test Bed (PTTB), a physical vehicle is not required.
2015-04-14
Technical Paper
2015-01-1634
Toru Ishino, Shinichi Takai
Transmission and vehicle control technology is advancing, and the shift operation format for the electronic gear selector is currently diverging from typical shifters, such as the shift lever located near the center console. As a result, automobile manufacturers find technical solutions that bridge the gear selection operations desired by drivers and the technical demands arising from control. A pushbutton-type electronic control gear selector device was developed with a differing operation direction for each gear operation. This enables instinctive operation that makes it easy for drivers to master the shift operation for each driving gear, while providing the same operating capability as a typical shift device. This new electronic control gear selector is scheduled for .
2015-04-14
Technical Paper
2015-01-0633
Fan Luo, Jinning Li, Xingxing Feng, Yunqing Zhang
The structure of a classic self-energizing synchronizer is presented, and a simulation model is developed for analyzing the synchronizer performance. The self-energizing synchronizer has a disk spring and several energizing teeth on the sleeve for increasing the shift force, besides, the asymmetric arrangement of chamfer teeth is applied to increase the torque for rotating ring and shift gears smoothly. The parameterized model of the typical synchronizer is developed with ADAMS for studying the synchronizer performance. In order to truly reflect the reality, the teeth of the synchronizer sleeve, outer ring and clutch gear are connected to the gear ring through bushing force alone, and the stiffness coefficient are obtained through the analysis of finite element model. Based on the dynamic model, the behavior of synchronizer with asymmetric arrangement of chamfer teeth, and the energizing effects of stiffness of disk spring and length of energizing teeth of sleeve are studied.
2015-04-14
Technical Paper
2015-01-1090
Sachin Bhide
This paper presents a method to model the transmission mechanical power loss to represent the unloaded and loaded losses on a planetary gearset. In this paper, the transmission losses are differentiated into losses due to fluid churning, losses due to fluid shear in between the walls of rotating parts, losses due to fluid shear between motor stator and rotor and losses due to the meshing of gearsets caused when the gears slide while transferring torque. Mesh loss model is physics based and losses are calculated at each mesh. Mesh losses depend on co-efficient of friction of gear material, number of teeth of the meshing gears and torque transfer. The fluid churning losses are calculated empirically and are specified for both laminar and turbulent flows. Fluid churning losses are calculated based on submerged depth of the gear component, oil properties and volume, gear geometry and speed.
2015-04-14
Technical Paper
2015-01-1089
Ajay Vasantrao Shinde, Prashant Jha, Anshuman Dev
Transmission is the drive line of a vehicle. Road load requirement are fulfilled by transmission system. Selection of gear ratios in early stage of design based on simulated vehicle performance reduces the cost and time in product design cycle. Selection of gear ratios based on acceleration performance in 1st and 2nd gear, maximum speed of vehicle achieved in last gear and grade-ability in first gear is explained in this paper for AMT. Automated manual transmission is a recent trend in two wheelers that fulfills fuel economy requirement and increases driving comfort. Gear shift strategy for AMT is derived based on fuel economy or drivability. This paper addresses the shift strategy that targets drivability of vehicle. Simulation done in GT power is done with India driving cycle to derive gear number against vehicle speed.
2015-04-14
Technical Paper
2015-01-1087
Juergen Greiner, Martin Grumbach, Albert Dick, Christoph Sasse
This is a preliminary version of the abstract to save the date, it will be replaced after discussion with the main author Dr. Jürgen Greiner ZF in short time. The discussion was not possible earlier, due to vacation of the authors and other stakeholders. Marketresearch shows the ongoing worldwide increasing acceptance and success of modern automatic transmissions in passenger cars. This success is based on the further developed of the driving comfort, shifting dynamic and - most important - fuel consumption reduction modern transmission systems show.
2015-04-14
Technical Paper
2015-01-1096
Robert Lloyd
Abstract The frequent occurrence of stops and starts on the typical postal delivery route makes it an attractive application for regenerative braking. The transmission described in SAE paper 2014-01-1717 contains all the functions necessary to implement hydraulic regenerative braking including the accumulator and reservoir. This paper describes the substitution of the hydro-mechanical transmission for the present transmission and estimates the performance benefits. The result in a low impact path for the US Postal Service to conform to the congressional mandate to improve the mpg of the vehicles and extend their useful life.
2015-04-14
Technical Paper
2015-01-1091
Fumikazu Maruyama, Moichio Kojima, Tomoyuki Kanda
The framework structure of this Continuously Variable Transmissions (CVT) differs from that of previous CVT. For this CVT, we used the framework structure of our CVT for midsize cars, and changed the pulley shaft support structure and consolidated the arrangement of the hydraulic control system and hydraulic supply unit. To achieve a higher level of both starting acceleration and fuel efficiency in which the CVT is installed, we set the ratio coverage to 6.2, which represents a 14% improvement. We set the Low side ratio to the same as the previous CVT and increased the OD side ratio To ensure that the components of the fundamental framework can be mounted in vehicles with widely varying engine capacities, we designed the components to tolerate torque levels comparable to those of a 1.8 liter engine while reducing their weight by approximately 12%.
2015-04-14
Technical Paper
2015-01-1092
Gabriela Achtenova, Ondrej Milacek
The closed-loop stand has its main advantage in a small power demand. The electromotor has to provide the sum of power losses in the stand, which are 20 to 40 % of the test power – depending on configuration of the test stand. This is especially important value when performing endurance long-run tests. That is the reason, why the closed-loop test stands are widely used for life-cycle tests of one speed (one or more stages) gearboxes. At CTU in Prague exists the closed loop test stand with a unique design, dedicated for testing of the complete automotive gearbox for transversal disposition of the drivetrain. The transmission is mounted in the test stand in the same manner as in the vehicle (with use of rubber silentblocks and reactional strut). Only one output from the differential is used. The differential is locked.
Viewing 1 to 30 of 2732