<p>Shift-by-Wire is about replacing the mechanical link between the automatic transmission and the shift lever with an electromechanical system. This will make new safety functions possible and assist the driver in other ways. </p><p>To do this, an actuator with a brushless DC motor is built into the transmission. It controls the position of the shift valve, which decides the driving position. </p><p>This thesis concerns the controlling of the brushless DC motor. This is done by programming a shift control unit with a Motorola HC12 microcontroller. The performance of the motor is then tested and evaluated.</p>

<p>The transmission is probably the drivetrain component with the greatest impact on driveability of an automatic transmission equipped vehicle. Since the driver only has an indirect influence on the gear shift timing, except for situations like kick-down accelerations, it is desirable to improve shift quality as perceived by the driver. However, improving shift quality is a problem normally diametrically opposed to minimizing transmission clutch energy dissipation. The latter has a great impact on transmission lifetime, and has to be defined and taken into consideration along with the notion of shift quality. The main focus of this thesis is the modeling of a drivetrain of an automatic transmission vehicle, and the implementation in MatLab/Simulink, including the first to second gear upshift. The resulting plant based on the derived equations is validated using data from a test vehicle equipped with a torque sensor located at the transmission output shaft. The shaft torque is more or less proportional to the driveline jerk, and hence of great interest for control purposes. Control strategies are discussed and a PID controller structure is developed to control the first to second gear upshift, as opposed to the traditional open-loop upshift control. Furthermore, the proposed controller structure uses the transmission output torque and the differential speed of the engaging clutch as inputs, to control the clutch pressure and the engine output torque, respectively. The structure is unsophisticated and transparent compared to other approaches, but shows great theoretical results in terms of improved shift quality and decreased clutch wear.</p>

Shift-by-Wire is about replacing the mechanical link between the automatic transmission and the shift lever with an electromechanical system. This will make new safety functions possible and assist the driver in other ways. To do this, an actuator with a brushless DC motor is built into the transmission. It controls the position of the shift valve, which decides the driving position. This thesis concerns the controlling of the brushless DC motor. This is done by programming a shift control unit with a Motorola HC12 microcontroller. The performance of the motor is then tested and evaluated.

The transmission is probably the drivetrain component with the greatest impact on driveability of an automatic transmission equipped vehicle. Since the driver only has an indirect influence on the gear shift timing, except for situations like kick-down accelerations, it is desirable to improve shift quality as perceived by the driver. However, improving shift quality is a problem normally diametrically opposed to minimizing transmission clutch energy dissipation. The latter has a great impact on transmission lifetime, and has to be defined and taken into consideration along with the notion of shift quality. The main focus of this thesis is the modeling of a drivetrain of an automatic transmission vehicle, and the implementation in MatLab/Simulink, including the first to second gear upshift. The resulting plant based on the derived equations is validated using data from a test vehicle equipped with a torque sensor located at the transmission output shaft. The shaft torque is more or less proportional to the driveline jerk, and hence of great interest for control purposes. Control strategies are discussed and a PID controller structure is developed to control the first to second gear upshift, as opposed to the traditional open-loop upshift control. Furthermore, the proposed controller structure uses the transmission output torque and the differential speed of the engaging clutch as inputs, to control the clutch pressure and the engine output torque, respectively. The structure is unsophisticated and transparent compared to other approaches, but shows great theoretical results in terms of improved shift quality and decreased clutch wear.

An automatic transmission is a device that is connected to the back of an engine and sends the power from the engine to the drive wheels. Its job is to keep the engine within a certain angular velocity. Although there are many epicyclic-type automatic transmissions in production, the related configuration design methods are still tedious and prone to human error. A simple and analytic methodology needs to be developed. Therefore, the purpose of this research is to present an efficient methodology for the systematic design of the epicyclic gear transmissions for automobiles. First, fundamentals and gear-shifting operations of the four-speed, five-speed and six-speed epicyclic-type automatic transmissions are illustrated to establish the design requirements. Second, based on the kinematic equations of the fundamental geared entities and the corresponding basic gear ratios, a procedure is applied to execute the kinematic and mechanical-efficiency analyses for the automatic transmissions. Third, two simple clutching-sequence synthesis methods are proposed and illustrated. One is based on the speed ratio equations, and another is based on the lever diagram. Next, a planar-graph representation is presented to arrange the desired clutches for each possible clutching sequence into the epicyclic gear mechanism. Then, the number of teeth of each gear is synthesized from assigning two or three desired speed ratios by the analytic method. Finally, a computer-aided design program for the clutching-sequence synthesis is developed with the considerations of the design requirements. With the above methods, the systematic designs of the 204 epicylic gear mechanisms are given for demonstrating the feasibility of the proposed methodology. The result of this work shows that the seven-link two-DOF epicylic gear mechanisms, the eight-link two-DOF Ravigneaux gear mechanism, and the nine-link two-DOF parallel-connected epicylic gear mechanisms could reach four-, six-, and six-forward speeds at most, respectively.

¡@An automatic transmission that is a transmission device between the engine and drive wheel, offers the vehicle while increasing and decreasing the speed mainly. Its job keeps the engine within a certain working rotational speed range.¡@Although there are many epicyclic-type automatic transmissions in production, the related design methods of lever diagram is not well developed.¡@Thus, the purpose of this research is to develop a systematic design of the epicyclic gear transmissions for automobiles with lever diagrammatical methodology.¡@First, fundamentals and gear-shifting operations of the four-speed and six-speed epicyclic-type automatic transmissions are illustrated to establish the design requirements.¡@Second, based on the basic theories of lever diagram, a procedure is applied to kinematic analysis for automatic transmission existed, and set up composite lever diagrams of 13 two-DOF seven-link epicyclic gear mechanisms and 190 two-DOF nine-link epicyclic gear mechanisms.¡@Next, a general clutching-sequence synthesis of lever diagrammatical method are proposed and illustrated. According to the limit range of lever dimensions established for four and five coaxial components, the clutching-sequences and the ranges of basic gear ratio of the feasible gear trains can be derived.¡@Finally, the planar-graph representation for arranging desired clutch and the number of teeth based on lever dimensions are applied to design six-forward speeds automatic transmission. The result of this work shows that the seven-link two-DOF epicylic gear mechanisms, and the nine-link two-DOF parallel-connected epicylic gear mechanisms could reach four- and six-forward speeds at most, respectively.

Lately the discussion on how big impact vehicles has on the environment has grown bigger and bigger. The vehicle manufacturers are building cars, trucks, and wheel loaders etc. that are getting more and more fuel efficient for every year. But where do the engineers at the companies make the improvements? The drive train is one area of the vehicle where many different sources of losses are found. The gearbox is one example, where the losses are both dependent and independent on the torque transferred by the gear pairs. The gearbox consists of several components that all of them contribute to the total system power loss. It is therefore of great interest to understand the magnitude of the losses in the gears, for different operating conditions, and also to be able to determine how they change with, for instance, rotational speed, oil viscosity. The goal of the master thesis was to make a study about the oil churning losses in a 6 speed automatic gearbox. This model makes use of calculations which were based on scientific experiments. This makes the loss calculations more advanced and accurate than the generalized formulas in most commercial software’s. This model takes into account only the oil churning and oil pocketing losses and shall not hold account for the windage losses or the other losses such as losses occurring due to bearings, seals, pumps etc. Due to time constraint a user friendly programme could not be written but the generated programme can be modified to make it easier for the user to input the data and produce results. All gears are modelled in simple modules built using MATLAB m-codes. Assumptions are made in the code when it came to choosing the oil viscosity. / På senare år har diskussionen om fordonens miljöpåverkan blivit allt mer intensiv. Fordonstillverkarna bygger bilar, lastbilar, hjullastare, etc., vars bränsleeffektivitet årligen når nya höjder. Var finns utrymme för förbättringar? Drivlinan är en del av fordonet där många olika förlustkällor påträffas; t.ex. växellådan, där förlusterna både är beroende och oberoende av det vridmoment som överförs av kugghjulsparen. Växellådan består av ett flertal komponenter som bidrar till systemets totala effektförlust. Det är därför av stort intresse att förstå omfattningen av förlusterna i kugghjulen, för olika driftsförhållanden, och att kunna bestämma hur förlusterna är relaterade till t.ex. rotationshastighet och oljeviskositet. Målet med examensarbetet var att göra en undersökning om oljeskvalpförluster (”oil churning losses”) i en 6-växlad automatlåda. Modellen använder beräkningar baserade på vetenskapliga experiment. Detta gör förlustberäkningarna mer avancerade och exakta än de allmänna formler som de flesta kommersiella programvaror nyttjar. Modellen tar endast hänsyn till oljeskvalpförluster och oljeficksförluster (”oil pocketing losses”) och tar icke hänsyn till vindförluster eller andra förluster såsom lagerförluster, friktion i tätningar, pumpförluster, etc. På grund av projektets tidsramar har förfiningen av programmets användargränssnitt prioriterats lågt; vid behov kan detta åtgärdas för att förenkla input och output av data. Alla kugghjul modelleras i enkla moduler som byggts som MATLAB-skript. Antaganden görs i koden när det gäller oljans viskositet .

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