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Viewing 1 to 30 of 2716
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
2015-01-1146
Matthew Barr, Krishnaswamy Srinivasan
In this paper, a new algorithm for the off-line estimation of wet clutch friction parameters is proposed for automotive transmissions, motivated by the usefulness of such an algorithm for diagnosing the condition of the clutch and transmission fluid in service. We assume that clutch pressure is measured, which is the case in dual clutch transmissions (DCT). The estimation algorithm uses measured rotational speeds and estimated accelerations at the input and output sides of a clutch to calculate clutch friction torque during a gear shift. Assuming for the purpose of estimation a static relationship between friction torque, clutch fluid film thickness, and clutch pressure, the viscous and contact components of clutch friction torque are estimated. From the contact friction torque, coefficient of friction data is generated. A Stribeck friction model is fit to the data, and parameters in the model are then calculated by applying linear least squares estimation.
2015-04-14
Technical Paper
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
2015-01-1138
Kyohei Sakagami
When fluctuations in the speed of rotation of the drive pulley are transmitted to the driven pulley via the metal pushing V-belt, the transmitted fluctuations become attenuated as friction force approaches a state of saturation. A method of predicting the friction drive limit in a transmission by measuring these changes in the fluctuation of the speed of rotation has been proposed. We determined to find the gradient of friction using the fluctuation in the speed of rotation of both pulleys by analytically solving equations of motion with the drive and driven pulleys regarded as a one-dimensional vibrating system connected by an elastic body. The gradient of friction is defined as the amount of increase in the coefficient of friction in relation to the increase in slippage between the belt and the pulleys.
2015-04-14
Technical Paper
2015-01-1135
Karthik Bhargav Siriyapuraju
The customer of today is sensitive towards shift quality. The demand is for a crisp and precise gear shift with low shift effort. The impulses from synchronizers make shifts feel notchy. After synchronization the blocker ring releases the sleeve. The sleeve then hits the teeth of the clutch body ring. The second impulse causes a phenomenon called double bump. This can be felt at the hand and makes a shift feel notchy or sluggish. An ideal way to overcome this is to optimize the detent profile. This paper explains in detail the various factors that contribute to the perceived shift feel. Various methods to optimize the forces on the knob by changing the detent profile are discussed. Gear Shift Quality Assessment( referred as GSQA henceforth) is a tool to acquire the required shift feel data. Using this tool shift efforts and kinematics of a 5 speed manual transmission are plotted for illustration. The calculations required to optimize the detent profile are explained in detail.
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
2015-01-1120
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
2015-01-1130
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
2015-01-1132
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
2015-01-1104
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
2015-01-1101
Jun Hakamagi, Tetsuya Kono, Ryoji Habuchi, Masahiro Tawara
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
2015-01-1103
Taiki Ando
We studied the reduction of pulley thrust and the deviation of the winding trajectory of the pushing V-belt on the pulleys to reduce friction loss due to slipping in metal pushing V-belt. Pulley thrust control, the amount of friction transmitted between the pulleys and the metal pushing V-belt, and a configuration that controls pulley inclination were three focal points in reducing transmission loss. The effects of the three methods of increasing transmission efficiency in OD ratio during cruising studied in this project were verified in tests. The new pulley thrust control employed reduced pulley thrust by approximately 40% and increased transmission efficiency by 2.6%. The trajectory of the pushing V-belt when it winds around the pulleys deviates from the theoretical winding radius due to the inclination of the pulley v-surfaces.
2015-04-14
Technical Paper
2015-01-1109
Ke Liu, Yulong Lei, Yao Fu
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
2015-01-1139
Haijun Song, Jian Song, Shengnan Fang, Yuzhuo Tai
Fully electric vehicle powertrain traditionally installs a single-speed transmission. Current research suggests that the performance of electric vehicle with a single-speed can still be widely improved. Despite the wide speed range of traction motor, the two-speed uninterrupted transmission employed instead of a single-speed transmission can enhance electric vehicle performance, and improve efficiency of the electric powertrain, and increase the mileage. The wheel torque at low velocities of the vehicle can be increased. In addition, the lower second-gear ratio raises the vehicle's top speed. The novel two-speed uninterrupted transmission system during power-on is specifically designed for electric vehicle in this article, in order to be compact, easy to control, and cheap to manufacture. It consists of a single-row planetary, a wet centrifugal clutch, a wet band brake, and two motor used to control the clutch and brake.
2015-04-14
Technical Paper
2015-01-1086
Darrell Robinette, Gabriel Gibson, David Szpara, Eugene Tehansky
As the number of fixed gear ratios in automatic transmissions continues to increase in the pursuit of powertrain system efficiency particular consideration must continue to be focused on optimize the design for shifting performance. This investigation focuses on the effect of shift time on the performance attributes of shift quality, durability, on schedule fuel consumption and enablers to further reduce shift time. A review of fundamental design features that enable reduced shift times in both planetary and dual clutch transmissions is presented along with key operating features of both the transmission and engine/prime mover. The durability of fast shift times during performance maneuvers is quantified through calculation of shifting clutch energy and power as measured on a powertrain dynamometer.
2015-04-14
Technical Paper
2015-01-1088
Tomohiko Usui, Tomoya Okaji, Tatsuya Muramatsu, Yoshiyuki Yamashita
A low-cost lock-up damper displaying a high level of damping performance has been developed for use in torque converters in automatic transmissions. The new damper was actualized by sharing parts (the turbine and damper components) and optimizing parameters for damping characteristics. The new torque converter displays equivalent conversion performance to a conventional model while reducing the width of the torus by approximately 30%. The combination of the lock-up damper and the small torus has made it possible to reduce torque fluctuation transmitted to the transmission to less than 50% with no increase in the overall width of the torque converter against a conventional model. This has reduced engine speed when the vehicle is cruising by 400rpm, resulting in an increase in fuel efficiency of approximately 2%.
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
2015-01-1091
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.
2015-04-14
Technical Paper
2015-01-1094
Tsuyoshi Aoyagi
For reducing CO2 emission, hybrid transmission technology is becoming important.Dry multiple-plate clutch system is efficient for reduce drug loss in hybrid transmission. However, there exist several challenges to realize high reliability during those operation.This paper describes new technology for dry multiple-plate clutch.The technology has been adopted to new FWD hybrid transmission system.
2015-04-14
Technical Paper
2015-01-1095
Makarand Kumbhar
Transmission designs over the years have been evolved significantly achieving more efficiency in terms of fuel economy, comfort and reduction in emissions. This paper describes a Dc motor based E-shift mechanism which automates an existing manual transmission and clutch system to give comfort and ease for gear shifting. The basic idea of E-shift mechanism is to make hassle free gear shifting of manual transmission at sole command of driver without any control strategy for automatic shifting as in case of Automated Manual transmission (AMT) . The E-shift mechanism will eliminate the manual efforts required for pressing clutch pedal and shifting gear, giving more ease while driving. The developed mechanism can be retro fitted on existing manual transmission without any major modification at lower cost. The E-shift mechanism uses two actuators for gear shifting and one actuator for clutch actuation.
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
2015-01-1108
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
2015-01-1087
Juergen Greiner, Martin Grumbach, Albert Dick
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
2015-01-0231
Qingkai Wei, Yulong Lei, Xingzhong Li, Boqin Hu, Zhengwei Liu
Shift process of automatic transmission (AT) can be achieved with hydraulic control system which operate clutches or brakes' engagement or disengagement. According to the state of engagement elements, shift process can be divided into torque phase and inertia phase. This article analyses shift process of automatic transmission with the lever method and got the variation of the transmission's output torque. Then, the control principle of clutch to clutch shift is studied. This article takes power on up shift as study example and minimum of transmission output torque fluctuations during shifting as control target, proposes inertia phase engine & transmission integrated control principle and entire shift process engine & transmission integrated control principle.
2015-04-14
Technical Paper
2015-01-0230
Shuhan Tang, Yanfang Liu, Xiao Han
As a significant control component of vehicles, automatic transmissions should have failure protection function. The failure protection function partly is determined by the hydraulic control system. However traditional design could not cover all of failures, and there is no general design method. A design method is proposed for designing the shift control oil circuit of the hydraulic control system with the failure protection function. . The design method is applied to optimize the hydraulic control system of a six-speed automatic transmission. The function of the optimized hydraulic control system is confirmed by the dynamic simulation. The results show that the design method can simplify the hydraulic control system without losing any original functions. The proposed design method is proved to be suitable for all kinds of hydraulic control systems of automatic transmissions.
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
2015-01-1661
Anthony Levillain, Pascale BRASSART, Béatrice Patte-Rouland
New directives and increasing competition push OEMs to get better performances (engine power increase), along with mass and size reduction (consumption). These evolutions lead to an increase of the thermal solicitations undergo by the clutches whereas their weight must be decreased, as it is one of the main influent factor on CO2 emissions. As the compactness is even more reduced for a Double Dry Clutch (DDC), this issue is critical. In order to improve the thermal behavior of the DDC, a CFD study has been performed. The present paper will introduce the first results obtained with a validated CFD model. The computations are performed on a DDC where the air flow around the rotating parts, along with the convection and the conduction of all solid parts are modeled. Then four different cases are used to evaluate the impact of holes on the air flow path and on the thermal behavior of the different parts of the system.
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
2015-01-1115
Xiaofeng Yin, Hua Sun, Wei Li
With the introduction of some kind of automatic transmission, the pure electric vehicle could obtain the benefits of downsizing the traction motor and increasing the overall performance of vehicle. Due to its relatively higher transmission efficiency and lower manufacturing cost, a 3-speed automated manual transmission (AMT) was used to replace the fixed ratio gearbox in an electric vehicle to investigate the possibility of performance improvement. Based on the parameter matching for the drivetrain system of the electric vehicle, a gearshift rule generating method based on the optimal motor efficiency was put forward, and the optimal efficiency gearshift rule for the investigated electric vehicle equipped with 3-speed AMT was established. And the optimal driveability gearshift rule was also generated for the purpose of comparison.
Viewing 1 to 30 of 2716