Dissertations / Theses on the topic 'Automated manual transmissions'

2012 - 2013
The goal of this thesis is the study of the automotive push-type dry clutches used in the Automatic Manual Transmissions (AMTs) and in the Dual Clutch Transmissions (DCTs) in order to improve their performances dur- ing the engagements phases. The push-type clutch is very widespread in the automotive sector because it allows many advantages in terms of cost, relia- bility, isolation of vibrations to the driveline, reduced axial size and stability to the facings wear [1]. Instead, the main advantages of an AMT, respect to the Automatic Transmissions (ATs), are improvements in terms of safety, reliability, and driving performances together with the reduction of the fuel consumption and pollutant emissions [2]. For these reasons by mixing the advantages of the push-type clutch with the advantages of the AMT it is possible to attain very high performance [3, 4]. On the other hand, the most important drawback of the AMT is the power interruption (the so called "torque gap") during the gear shifts events. To solve this problem in the last decade the DCTs have been introduced. In fact, by applying the engine torque to one clutch just as the engine torque is being disconnected from the other one [5] the torque transmission is allowed also during the gear shift phases. In this light, the work developed for this Thesis aimed at providing useful information both to the clutch designers and to control algorithm designers in order to enhance the performances, and consequently, the market di usion mof the AMT and DCT transmissions. The thesis is organized as follows. Chapter 2 is an introductory section on the historical evolution of the clutches and of the automotive transmissions systems. Chapter 3 deals with the transmissibility torque model by consid- ering the main factors which a ect the elastic components of a push-type clutch and the friction coe cient. In the Chapter 4 application of control algorithms both for a two DoFs driveline model and for a ve DoFs model are introduced. Finally, the Chapter 5 underlines the concluding remarks. [edited by author]
XII n.s.

Automated gear-shifts are critical procedures for the driveline as they are demanded to work as fast and accurate as possible. The torque control of a driveline is especially important for the driver’s feeling of driveability. In the case of gear-shifts and torque control in general, the boost pressure is key to achieve good response and thereby a fast gear-shift. An experimental study is carried out to investigate the phenomena of boost pressure drop during gear-shift and gather data for the modelling work. Results confirm the stated fact on the influence of boost pressure drop on gear-shift completion time and also indicate a clear linear dependence between initial boost pressure and the following pressure drop. A dynamic predictive model of the engine is developed with focus on implementation in a heavy duty truck, considering limitations computational complexity and calibration need between truck configurations. The resulting approach is based on a mean value modelling scheme that uses engine control system parameters and functions when possible. To be able to be predictive, a model for demanded torque and engine speed during the gear-shift is developed as reference inputs to the simulation. The simulation is based on a filling and emptying process throughout the engine dynamics, and yields final values of several engine variables such as boost pressure. The model is validated and later evaluated in comparison to measurements gathered in test vehicle experiments and in terms of robustness to input and model deviations. Computer simulations yield estimations of the boost pressure drop within acceptable limits. Consid- ering estimations used prior to this thesis the performance is good. Input deviations and modelling inaccuracies are found to inflict significant but not devastating deviations to the model output, possibly more over time with ageing of hardware taken into account. Final implementation in a heavy duty truck ecu is carried out with results indicating that the current implementation of the module is relatively computationally heavy. At the time of ending the thesis it is not possible to analyse its performance further, and it is suggested that the module is optimized in terms of computational efficiency.

In an automated manual transmission it is desired to have zero torque in the transmission when disengaging a gear. This minimizes the oscillations in the driveline which increases the comfort and makes the speed synchronization easier. The automated manual transmission system in a Scania truck, called Opticruise, uses engine torque control to achieve zero torque in the transmission.In this thesis different control strategies for engine torque control are proposed in order to minimize the oscillations in the driveline and increase the comfort during a gear shift. A model of the driveline is developed in order to evaluate the control strategies. The main focus was to develop controllers that are easy to implement and that are robust enough to be used in different driveline configurations. This means that model dependent control strategies are not considered.A control strategy with a combination of a feedback from the speed difference between the output shaft speed and the wheel speed, and a feedforward with a linear ramp, showed very good performance in both simulations and tests in trucks. The amplitude of the oscillations in the output shaft speed after neutralengagement are halved compared to the results from the existing method in Scania trucks. The new concept is also more robust against initial conditions and time delay estimations.

La transmission à double embrayage a été introduite dans les véhicules afin d'améliorer le confort de conduit, l'économie de conduite et de diminuer le temps de changement de vitesses. La gestion du double embrayage joue un rôle important sur le confort de conduite. L'objectif principal de ce travail concerne alors la synthèse des lois de commande du double embrayage en phase de décollage et lors du changement de vitesses. Le mémoire est structuré de la façon suivante : le premier chapitre propose un état de l'art sur le groupe motopropulseur, la modélisation et la commande du groupe motopropulseur. Le second chapitre s'intéresse à la modélisation du groupe motopropulseur à double embrayage : dans une première partie, un modèle complet à simuler est développé, puis la deuxième partie propose une simplification de modèle en vue de la commande. Le troisième chapitre aborde les lois de commande du double embrayage en utilisant la technique de commande par mode glissant pour les systèmes multivariables. Le quatrième chapitre propose l'utilisation des modèles flous du type Takagi-Sugeno pour la synthèse des lois de commande. Dans une première partie, des lois de commande basées sur un modèle Takagi-Sugeno prenant en compte des incertitudes et des perturbations sont établies. Afin d'améliorer la performance de la loi de commande lors du changement de vitesses supérieures, la deuxième partie présente une loi de commande basée sur un modèle de Takagi-Sugeno incertain et perturbé à commutations. Enfin, des résultats de simulation obtenus en considérant le modèle complet développé dans le chapitre 2 sont donnés.

碩士
國立屏東科技大學
車輛工程系所
99
Vehicles with automatic manual transmission (AMT) for gear shift offer many advantages in terms of reduction of fuel consumption, improvement of driving comfort, and shifting quality. The AMT can either automatically shift gears using appropriate actuators mounted on manual transmission (MT) according to driver’s power command and driving conditions, or in accordance with driver’s gear command through shifting level. Conventional AMT for vehicles powered by internal combustion engine (ICE) requires an electronic controlled clutch to separate or engage engine power to the MT for gear change smoothly, because of high inertia of the ICE, which complicates the system and thus with high cost. In this study, an AMT design without the use of the clutch for electric vehicle (EV) is studied. The idea is mainly based on the fact that the inertia of the power motor of EV is generally quite small compared with that of the ICE. This enable synchronize electronically the rotating speed of driving gears with driven gears in the MT gearbox during the gear change operations. This thesis introduces the design of the CL AMT and its feasibility was verified through a test rig.

碩士
國立交通大學
機械工程系所
92
Automated Manual Transmission (AMT) system is gradually prevailed in recent years since it has high transmission efficiency, auto shifting capability, and low cost. Vehicles from high quality sports cars like BMW M3, Ferrari 355, Alfa Romeo 156, etc., to general sedans like Opel Corsa, Renault Twingo, etc. have introduced such system. However, the key point that AMT can’t completely substitute Automated Transmission (AT) system is the smoothness that a auto clutch system on AMT can’t transmit power as smooth as a torque converter on AT. Clutch control of AMT system is the main subject in this study, which includes three objectives: dynamic modeling, control function design, and optimization. The first objective is to create a dynamic model of AMT system, which includes engine, clutch, clutch actuator, gear box, and vehicle loading. Clutch actuator is focused in this model, since this study is a project cooperating with Industrial Technology Research Institute (ITRI) to modify a prototype of clutch actuator. The second objective uses the dynamic model created before to design a control function for the clutch actuator, some control methods and parameter turning methods are introduced here. According to the control model and dynamic model, a complete shifting process from controller to vehicle dynamic is simulated in this study. The third objective is optimization, some parts in the clutch actuator and some parameters of the control function are optimized to give a better performance on clutch engagement and disengagement.

碩士
國立中正大學
機械工程學系暨研究所
101
Due to discharging for battery is usually over its rated current, a electric scooter has problems of low driving efficiency and short life of battery. Especially, a battery's output current is much higher when a electric scooter is drove on a ramp. In order to solve above problems, people are used to reducing voltage of motor to control battery's output current. However, it's confirmed by an experiment that reducing motor's voltage can't improve driving efficiency of a electric scooter. Therefore, I choose to install an Automated Manual Transmission on a electric scooter to limit battery's output current and depend on the value of current to choose a suitable gear ratio to drive.

碩士
國立中興大學
機械工程學系所
101
The V-belt Continuously Variable Transmission (CVT) system is widely used in Scooters nowadays. The major mechanism of the traditional CVT consists of centrifugal rollers, drive pulley, torque spring, driven pulley, and reaction skewed slot. The centrifugal rollers, torque spring, and reaction skewed slot are used for changing the transmission ratio which follows the engine speed and the rear wheel load. CVT is a good transmission system because it has advantage of simple structure, easy operating and convenient maintenance. But it’s not good enough because its transmission efficiency is lower than the gear types transmission system, and the transmission ratio change locking with the engine speed varying from low speed to high speed. This results higher fuel consumption. In order to improve the transmission efficiency, promote the driving power and reduce the fuel consumption, a new design of transmission system is needed. The aim of this study is to design a brand new Mechanical Manual-Automatic Continuously Variable Transmission (MMACVT) system to overcome the limitation of the traditional CVT mechanism. A mechanical control mechanism, which is driven by a servo motor, is used in this MMACVT for changing the transmission ratios. Therefore, the MMACVT system also has the advantage of simple structure, easy operating, and convenient maintenance. The MMACVT system can be used for different types of driving power and different kinds of light vehicles. Consequently, the MMACVT system can be expected to get better power transmission and higher energy transferring efficiencies. At the present stage, a better fuel consumption efficiency has been proved by road test for the new MMACVT system. The next stage, we will improve the fabrication process and operation method for the MMACVT system.

This research systematically compares various electrified vehicles based upon electrification levels and powertrain configurations. A series of novel hybrid electric powertrain systems based on the newly proposed Hybridized Automated Manual Transmission (HAMT) concept are introduced. One representative hybrid powertrain system is selected to illustrate their operation principle. The new HAMT-based hybrid powertrain system overcomes the bottleneck problem of mainstream power-split hybrid systems with relatively low torque capacity and the constraint for utility vehicle electrification, and presents advantages over other hybrid powertrain systems in efficiency and costs. In addition, the new hybrid powertrain system can deliver continuous output torque by filling torque hole during gearshift, through coordinated control of engine, motor, and transmission, improving the driveability of regular Automated Manual Transmission (AMT), whose applications have been hampered by torque hole over the past years. The proposed HAMT-based hybrid systems with improved torque capacity, efficiency, costs, and driveability come with a compact design and more flexible operation through the amount of gearwheels equivalent to a 5-speed AMT to achieve 8 variable gear ratios for the Hybrid Electric Vehicle (HEV) mode and Electric Vehicle (EV) mode operations of a Plug-in Hybrid Electric Vehicle (PHEV). Model-based optimization, dynamics analysis, and powertrain control strategies have been introduced for a PHEV with a representative 8-speed HAMT. Vehicle simulations have been made to study and verify the capability and advantages of the new electrified powertrain system. Firstly, the operation principles of various HAMTs are discussed through detailed power flows at each gear. The fundamental principles of typical HAMT variations are explained using a new power-flow triangle with three ports. Based on the concept of Torque Gap Filler (TGF), a set of HAMT system designs have been introduced and closely studied to provide continuous and stable output torque. The selected hybrid powertrain system equipped with a representative HAMT system supports both HEV mode and EV mode with eight variable gear ratios for each mode. Among the eight forward gear ratios, six are independent and two are dependent on the other gears. Combinations of dog clutches at all gears are designed to eliminate torque holes. Gear ratios and gearshift schedule of the 8-speed HAMT are designed to support the new design. Torque paths at each gear are illustrated and transient scenarios including gearshifts and mode transitions are investigated. The gear ratio of each gear is determined by considering the unique clutch combination of this HAMT, using the classical gear ratio design method - Progressive Ratio Steps. Due to the broader high efficiency operation region of electric motors, a model-based optimization method is used to determine the two gear ratios for the EV mode to achieve better fuel economy and avoid unnecessary gearshifts. Dynamic Programming (DP) is used to identify the optimal gear ratios, considering vehicle fuel economy for the EPA75 and Highway Fuel Economy Fuel Test (HWFET) driving cycles. The 4th and 6th gears among the eight gear ratios in the EV mode of PHEV are based on 2-speed gearbox design for an EV, and their gearshift schedules are determined by optimization. Combining the considerations for the hybrid and EV modes of a PHEV, key elements of the proposed HAMT system, including gearshift schedule, clutch combination, and gear ratios for highly efficient operation are determined. The more challenging driveability issues during mode transition from EV to HEV and power-on gearshift with TGF during acceleration are addressed. Both of these two operations require relatively high power/torque outputs and involve multiple powertrain components, including engine, motor, main clutch and gearbox, within a period of two seconds. A lumped-mass model (LMM) of the HAMT-based hybrid vehicle is built to analyze the driveline dynamics in two steady states and four transient states. Each of these states is analyzed independently, according to states of main clutch and gear selectors, considering different phases of the TGF operation and EV-HEV mode transition. The methods for modeling the discontinuity of clutch torque and dog clutch inside the HAMT are discussed to support the subsequent powertrain system modeling and control development. To identify the optimal control schemes for model transition and gearshift, the model-based optimization method for a post-transmission parallel PHEV is developed. The vehicle powertrain model was initially built using AUTONOMIE and MATLAB/Simulink with primary parameters from a prototype PHEV and its dSPACE ASM model developed at University of Victoria. System dynamics in EV mode and hybrid mode are described as a group of state-space equations, which are further discretized into matrix form to simplify the optimization search. A DP-based global optimization method is used to identify the optimal control inputs, including engine torque, motor torque, and main clutch torque. Four principles for desirable EV-HEV mode transitions are extracted based on the results of the optimization. To model different operation modes and complex power flows, the initial baseline powertrain system model is then replaced by a customized MATLAB/SimDriveline model. In this new physics-based powertrain model, gearshift actuators and controller are added to model the gearshift and mode transition processes. To achieve good driveability, the TGF feature of the HAMT design is split into five transient and two steady phases, each corresponding to a fundamental operating mode. Control logics of upshift and downshift, as well as EV-HEV mode transition are introduced. Four principles of mode transition derived from global optimization results are introduced for powertrain system control. Simulations of the HAMT-based hybrid powertrain operations have been carried out to verify the functionality and advantages of the proposed HAMT design in achieving excellent driveability during mode transition and gearshifts. Through controlled coordination of engine, motor and main clutch, EV-HEV mode transition can be achieved smoothly within a period of 2-3 seconds. Even slight driveline fluctuation can be eliminated by dedicated anti-shuffle control with the motors as actuators. The same simulation model also demonstrates excellent driveability during power-on gearshift. Comparing simulation results with and without TGF shows that this new hybrid powertrain system can effectively eliminate torque holes during gearshift. With the demonstrated advantages of this new system in efficiency, torque capacity, simplicity in design and manufacturing costs over its existing rivals, the research provides a promising alternative to mainstream power-split hybrid electric powertrain system design.
Graduate

碩士
國立屏東科技大學
車輛工程系所
103
In this thesis, a new gear-shift control strategy for an electric bus clutch-less automated manual transmission (AMT) is studied. This control method is developed for improving gear-shift efficiency and reduces total friction work of the synchronizer during the gear-shift. The dynamic of the driveline is described and the operation details of synchronizer are studied. A new layout of the transmission is modified from a conventional AMT showed in this thesis that enables to control an adjacent gear-shift actuator independently at the same time. This modified AMT could apply the new gear-shift control strategy. Simulation results have demonstrated that synchronous time and total friction work of the synchronizer are reduced during gear-shift with the new gear-shift control strategy. The optimizations of transmission system design and control strategy are necessary to achieve better performance of the gear-shift efficiency. In the future, an experimental test rig is required to verify the feasibility of the new gear-shift control strategy.

碩士
國立臺北科技大學
車輛工程系所
95
The shifting system of a vehicle can be divided into manual transmission (MT) and automatic transmission (AT). Because of the high efficiency in the MT system, MT systems are popularly used in vehicles. But it is found that power shock exists due to shifting with incorrect timing while a MT system is shifting. Such a problem makes drivers exhausted in driving. Therefore, automatic transmission system has gradually replaced MT system in passenger cars and some other vehicles. However, an AT system generally has 7% less transmission efficiency and 30% higher cost than those for a MT system. Thus an automatic manual transmission (AMT) system is the key to solve such problems. AMT system is adding functions of automatic clutch and gear-shifting to the traditional manual transmission system. The main parts in AMT system include automatic clutch, gear box and electric control system. The transmission control unit (TCU) in AMT system controls the functions of clutch engaging, gear shifting and fuel throttling by electrics or hydraulics. TCU also decides the optimal gear-shifting by vehicle speed and throttle opening to make the vehicle having smooth speed and power output in the transition of gear shifting. With the aid of AMT system, a vehicle can have higher transmission efficiency, lower fuel consumption, and higher driving comfort.

碩士
國立臺灣大學
機械工程學研究所
105
Today, the automatic clutch control system using DC motor drive has been widely used. Because DC motors contain brush and slip ring, and they are consumable where the durability of DC motor and energy converted efficiency are its shortage. In addition, the position control of DC motors is not as accurate as servo motors. Due to these reasons, a DC motor is replaced by a permanent magnet synchronous motor in this thesis. The investigation of disturbance rejection based on the disturbance observer is also discussed. The type of observer can be conventional single-observer and Torque and Speed dual-observer. The mathematical model of two different observer types will be built. And The effect of torque disturbance on the motor position control about (1)no observer, (2)single observer and (3)dual observer will be analyzed by frequency response. The feasibility and performance for permanent magnet synchronous motor are validated and compared in the experimental results. Moreover, In this thesis, the working principle and experiment results of the number of estimators and the bandwidth selection have been discussed in detail.

碩士
國立中正大學
機械工程學系暨研究所
103
In this thesis, a specially designed automated manual transmission is prototyped and implemented in a 48-volt electric two-wheel. The transmission includes not only a set of manual gears, a collar, a collar driver, and a potentiometer to detect the position of collar but also the single-directional beating to replace conventional clutches. Since this transmission adopts manual gears and its “clutch” consumes no power, it is the most energy-saving transmission design for the present industry. In this thesis, mechatronic design is detailed and experimental data verifies such a design.

碩士
國立屏東科技大學
車輛工程系所
103
The objectives of this thesis are analyzing and design the shifting mechanism and synchronizer assembly of an automatic manual transmission (AMT) developed by NPUST. Because of without the use of clutch in the AMT, mechanism synchronizers are required of gear shifting process. The works are proceeded firstly by developing a program to simulate every step of synchronization process during gear shift. Then a set of modified parameters of the synchronizer are proposed for smoothing gear shift operations. Furthermore, a brand new shifting mechanism was designed for more smooth and responsive shift control. Finally, a test rig was established to verify the performance of the proposed shifting mechanism. Throughout all the feasibility studies, numerical simulation, and experimental tests, it was proved that the new designed shifting mechanism could achieve smooth shift and simplify the control logic successfully.

碩士
國立屏東科技大學
車輛工程系所
103
This thesis is aimed to develop an automatic shifting control strategy for a micro electric vehicle (EV). The power package of the EV is composed of two 2 KW BLDC motors and three gear ratio clutch-less automatic manual transmission (AMT). With the combination of two motors and the multiple gears transmission, the vehicle is possessed with the characteristics of high torque and high rotation speed. The purpose of the use of two motor is to avoid torque hole during gear shifting processes. The Vehicle Control Unit (VCU) in this thesis is the Renesas RH850-F1L micro controller that fits the ISO26262 standard (the standards of vehicle safety). With the micro controller, an automatic shifting controller and gear shift strategy were designed. The works of this thesis can be divided into three parts, namely, function development of the micro controller, gear shift control algorithm design for the AMT, and finally automatic gear shift strategy for the AMT. The target was to achieve a top speed of 45 km/hr on level road, 8 km/hr for a slope of 27%. In order to complete automatic shifting function in a short time, this paper applied adaptive control theory for speed synchronization control. The design method of shifting strategy is based on the characteristics curve of the power motors and the gear ratio of the AMT. Furthermore, road loads and driver requests are considered to establish appropriate timing for up and down gear shifts. Experimental results have shown that, with the integration of the micro controller (RH850) and automatic shifting strategy, the EV could execute shifting process automatically and successfully and possessed with satisfactory driving performance and automatic shifting function for all driving conditions.

碩士
國立中正大學
機械工程學系暨研究所
103
Electric two-wheels without transmission encounter unreasonable currents necessarily provided by battery and severely low energy-efficiency when running up a slope. To be sure, both of the life of batteries and driving range of the vehicle are short, and fortunately this thesis develops a solution thereto. Such a solution includes a specially designed Automatic Manual Transmission to regulate motor currents. Therein, a single-directional bearing working embedded controller replaces a conventional clutch for energy saving. In this work, embedded-controller design is presented and experimental data verifies such a design.

碩士
國立屏東科技大學
車輛工程系所
100
Electric vehicles equipped with automatic manual transmission (AMT) offer many advantages in terms of transmission efficiency, improvement of driving comfort, and shifting quality. Conventional AMT for vehicles powered by internal combustion engine (ICE) requires an electronic controlled clutch to separate/engage engine power for gear change smoothly, because of high inertia of the ICE. This complicates the system and thus raises higher cost. Hence, a Clutchless Automated Manual Transmission (CLAMT) with the advantages of high efficiency, low cost, and simple structure is adopted and developed in this thesis. The objective of this study is focused on gear-shifting control technique of CLAMT, including model parameters identification, synchronization control during gear engaging and motion control of shift actuated mechanism. Through theoretical analysis, simulation, as well as experimental verification, the results confirm that the designed control technique is able to make smoothly gear-shifting and the feasibility of CLAMT is verified.

碩士
國立臺北科技大學
車輛工程系
107
Due to the fast and accurate response of the traction motor (TM), active speed synchronization control can be realized by controlling the speed and torque of the TM during the gear shifting process. Therefore, the clutch is no longer needed for the powertrain system. In this thesis, the vehicle longitudinal dynamics model, the powertrain system model and the synchronizer model are established for the electric vehicle equipped with a two-speed Clutchless Automated Manual Transmission (CLAMT). According to the shifting process, the equations of motion for each stage are simulated to analyze the dynamics of the vehicle during gear shift process. Such that the gear shift control strategy can be designed accordingly. The gear shift process can be divided into five processes which are torque release, gear shift to neutral, active speed synchronization, target gear engagement (mechanical synchronization), and torque recovery. A rule-based gear shift control strategy architecture is used in this thesis. Model predictive control (MPC) with the consideration of the TM dynamics is employed to control the TM speed which is during the active speed synchronization phase. Simulation results show that the dynamic response of TM has a significant impact on the jerk during the torque release and torque recovery phase. The response and overshoot of the proposed MPC are faster and smaller than those of the PI controller during the active speed synchronization process. Therefore, the time for active speed synchronization and the jerk for gear engagement are effectively reduced.