In recent years, due to a need to reduce emissions, the automotive industry has focused on increasing vehicle efficiency. One of the areas being examined for potential improvement is the automatic transmission; specifically, the torque converter clutch damper. The better the performance of the damper, the more time the torque converter can be kept in the optimum locked position, thus increasing vehicle efficiency. Currently a large number of vehicle manufacturers use transmission technology sourced from external OEMs; due to a lack of available performance data or validated simulations, sometimes vehicle manufacturers are not able to fully understand the behaviour of the damper. If damper performance (or interactions with other components) cannot be fully assessed during the design development phase, key issues may become known too late in the development process. Thus a deeper understanding of the processes of experimentally characterising and simulating torque converter dampers is required. This thesis describes the development of an arc spring torque converter damper simulation, including the gathering of the experimental data required to validate the simulation. The simulation is used to draw conclusions on the impact of excitation signal form on damper behaviour, leading to new knowledge on the signals required to experimentally characterise a damper. In this thesis a methodology for (and implementation of) the characterisation of torque converter dampers is detailed. It was found that existing available technologies (e.g. fired engines, electric dynamometers) were either too inflexible or prohibitively expensive; thus a novel high frequency mechanical pulsation generator was developed. This solution was developed from a 4 cylinder motored diesel engine; the cylinders are filled with compressed air and the crankshaft driven using an electric dynamometer. Simulation and experimental data has confirmed that mean torque can be controlled using the input dynamometer, with the compressed air producing fluctuations of up to 900Nm amplitude. However, it was found that the frequency of the output pulsations varied from a fired engine; this is due to reactions between the pulsation generator and the stiffness and inertias of other components on the rig. A review of the performance of the novel pulsation generation concept against other damper excitation methods was also conducted. It was determined that fired engines and electric motors are more suitable for durability testing; the flexibility of the electric motors and the low running costs of the pulsation generator suit damper performance tests. The second phase of this project was to develop a simulation of a two-stage arc spring turbine damper. This damper consists of three inertias, separated by two spring sets; the outer spring set has 3 individual arc springs, while the inner spring set has 5 nested pairs. The principle of conservation of angular momentum is applied to each of the three inertias in order to calculate their individual accelerations. This method is also applied when calculating the acceleration and movement of the springs; the arc springs are discretised into mass and (massless) spring segments. Two features not previously seen in literature are included in the simulation; hardstops and nested springs. The physical hardstops limit the movement of the spring sets (relative movements of the inertias). In this study, the nested springs were simulated as a pair of parallel springs, rather than as a single stiffer arc spring; this is due to the friction that occurs between the springs (the inner race of the larger spring forms the housing for the inner spring). These two features highlight the need for hardware examination before simulation development; disassembling the hardware also allows the location of hardstops (and other features) to be measured rather than relying on the test data. Once a damper simulation was designed, a methodology for simulation parameterisation was required; parameterisation is the process of improving simulation performance through iterations of estimated parameters. The simulated damper was excited using sampled experimental data; to maximise parameterisation process efficiency, each time a parameter change was made, a set of key test points were selected in order to assess simulation performance change. It is not recommended that single test points be examined individually; parameter changes may improve simulation performance at one test point but have an adverse reaction at another. A clear causal relationship between simulation timestep and accuracy (as well as simulation run time) was found; a link between the number of discretised segments and simulation accuracy (and run time) was also confirmed. It was determined that 8 segments was optimal for the inner springs and 18 outer segments offered the best balance between computing power and simulation time. A variety of methods for analysing damper (and simulation) performance are presented in this thesis; it was found that for the 2.5 bar torque curve experimental data set the simulation performs excellently, with on average less than 5% error. Overall torque error is less than 10% across the tested speed range (900 to 2800rpm), with mean torque differences between simulated and tested order magnitudes of less than 5Nm. It has been determined that hysteresis loops are not an accurate predictor of real-world damper performance; while they can approximate general trends, they do not cover the normal operating condition. In the final phase of this thesis, the validated simulation has been used to investigate excitation signal, areas of poor damper performance and the link between speed and damper stiffness. By subjecting the simulation to a variety of sinusoidal input signals, it was established that if a sinusoidal signal approximates the 3 most dominant frequencies in a real signal, the damper will behave in a representative manner. Additional orders that have lower frequencies than the dominant order will have a greater impact on the attenuation behaviour of the damper; the effect of additional orders on attenuation behaviour is also linked to their magnitude (relative to the dominant order). A methodology for efficient damper mapping is proposed; the key aim is to produce a dataset that will minimise the length of the parameterisation process while capturing key damper behaviours. It was found that the magnitude of the torque oscillations used to excite the damper is linked to parameter adjustment impact, though this relationship is not linear for all parameters; an approximate level of 300Nm should be used for excitation. Parameters such as spring stiffness and plate inertias are more likely to have a substantial impact on damper performance at frequencies below 70Hz; friction tuning factors are impacted more by magnitude changes at frequencies above 150Hz. It has been demonstrated that while speed can have an effect on magnification ratio, this effect is far less significant at mean torques above the knee point and when sinusoidal input magnitude is kept at or above 300Nm. It was concluded that neither engine speed nor precise excitation magnitude must be replicated in order to predict approximate performance. During the investigation into areas of poor damper performance, it was confirmed that the trend of increasing magnification ratio with lower frequencies ( < 30Hz) seen in experimental data continued. Simulation testing above 140Hz revealed that there is not a linear relationship between increased frequency and increased magnification ratio; these areas of magnification ratio spikes are likely due to system resonances. It has been confirmed that while fluctuation magnitude does impact magnification ratio, fluctuation frequency has the most significant (dominant) impact. Finally, the effect of speed on apparent damper stiffness was investigated for both hysteresis loop testing and across a range of outer spring vibration angles; it was confirmed that increasing speed does result in non-homogeneous compression of the springs. It was established that while speed can have an effect on spring stiffness, this effect will vary significantly depending on the movement range (vibration angle) of the spring. / The largest increase in spring stiffness with speed is seen when segments of the spring become inactive (cease to move), hence why the effect of speed is more substantial at vibration angle of < 10°. The simulation was used to confirm the theories linking speed and stiffness found in the literature; higher speeds increase frictional forces, slowing damper segments, resulting in reduced movement. The findings of this thesis are relevant to damper simulation and testing engineers; by expanding knowledge of damper behavioural responses to high frequency excitation signals, as well as demonstrating an effective method for producing validated damper simulations, it is hoped that the vehicle design process will be more efficient and damper modifications more effective.

The automotive industry has long been searching for efficient ways to improve vehicle performance such as drivability, fuel consumption, and emissions. Researchers in the automotive industry have tried to develop methods to improve fuel consumption and reduce the emission gases of a vehicle, while satisfying drivability and ride comfort issues. Today, by developing computer/software technologies, automotive manufacturers are moving more and more towards modelling a real component (prototype) in a software domain (virtual prototype). For instance, modelling the components of a vehicle's powertrain (driveline) in the software domain helps the designers to iterate the model for different operating conditions and scenarios to obtain better performance without any cost of making a real prototype. The objective of this research is to develop and validate physics-based powertrain models with sufficient fidelity to be useful to the automotive industry for rapid prototyping. Developing a physics-based powertrain model that can accurately simulate real phenomenon in the powertrain components is of great importance. For instance, a high-fidelity simulation of the combustion phenomenon in the internal combustion (IC) engine with detailed physical and chemical reactions can be used as a virtual prototype to estimate physical prototype characteristics in a shorter time than it would take to build a physical prototype. Therefore, the powertrain design can be explored and validated virtually in the software domain to reduce the cost and time of product development. The main focus of this thesis is on development of an internal combustion engine model, four-cylinder spark ignition engine, and a hydrodynamic torque converter model. Then, the models are integrated along with the rest of a powertrain's components (e.g. vehicle longitudinal dynamics model) through acausal connections, which represents a more feasible physics-based powertrain model for model-based control design. The powertrain model can be operated at almost all operating conditions (e.g. wide range of the engine speeds and loads), and is able to capture some transient behaviour of the powertrain as well as the steady state response. Moreover, the parametric formulation of each component in the proposed powertrain model makes the model more efficient to simulate different types of powertrain (e.g. for a passenger car or truck).

No description available.

No description available.

In order to make a profit in any earthmoving operation it is important to plan the operation, select the appropriate equipment and use the haul units efficiently in order to obtain the maximum productivity. Maximizing productivity is one of construction project management personnel's primary objectives, but can also be one of their greatest challenges. The need for effective productivity planning is obvious since productivity ultimately translates into profit. In order to plan an earthmoving operation it is important to understand the travel times of the hauling equipment. Travel time is a variable that, in turn, depends upon other variables associated with the haul unit, and the haul road conditions. Presently there is no travel time model that appropriately considers these factors and simulates the interactions among them such that more detailed analysis could be performed. Such a model needs to be developed. The objective of this research is to develop a detailed model to simulate the travel time considering, in the amount of detail needed, the variables upon which travel time is dependent. The key in the development of the model is the calculation of acceleration. The simulation of how instantaneous acceleration varies may be a complex procedure because instantaneous acceleration is a function of numerous variables, many of which are in turn functions of the velocity and position, which are themselves integral functions of acceleration. The acceleration of a vehicle is dependent on the vehicle characteristics, road conditions, and operator. It is very difficult to consider changes in instantaneous acceleration by using analytical procedures. A numerical method should be used in order to analyze the complex system and determine the travel time or velocity profile of the vehicle. MATLAB software was used to analyze and solve the complex system numerically. A model that considers that the machine is working at full capacity was developed. It considers the variables that affect travel time in the amount of detail needed. The impact that the operator has in the machine performance can be highlighted after a comparison of the results obtained with actual field data, once the model is calibrated. / Master of Science

A simulation model for an automatic gearbox with primary retarder has been constructedand implemented, in this thesis. Together with other modelled vehicle components, thismodel could for example be used for fuel consumption estimation or optimizing vehicleparameters.The mechanical components and the control system inside the automatic gearbox weremodelled separately and then assembled into the nal gearbox model, using the objectorientedprogramming language Modelica. Modelica ensures that each individual componentcan be reused in other models.The gearbox model was validated through a number of test cycles designed to capturedierent vehicle behaviours. The test cycles were recreated in the simulation environmentand the simulation results could be compared to a real vehicle performing the same tests.Validation showed that the model succeeded in its goal, that the implemented model isreproducing similar behaviour as the real gearbox. With gear shifts taking place in aboutthe same situations and converter locking/unlocking occurring the same time in the simulationsas in the real vehicle testing. / I det här examensarbetet har en simuleringsmodell för en automatisk växellåda med primär retarder utvecklats och implementerats. Tillsammans med andra modeller från fordonoch drivlina skulle denna simuleringsmodell kunna användas för att uppskatta ett fordonsbränsleförbrukning eller till att optimera olika fordonsparametrar.De olika mekaniska komponenterna samt kontrollsystemet i växellådan modellerades separat.Dessa modeller kunde sedan sammanfogas för att bygga den slutliga växellådsmodellen.Alla modeller implementerades i det objektorienterade programmeringsspråket Modelica,som tillåter en stor återanvändningsbarhet till vardera enskild komponent.Den implementerade modellen verierades genom ett antal provcykler, utformade för attfånga olika beteenden hos växellådan. Dessa cykler har återskapats i simuleringsmiljön ochmed det kunde resultat från simuleringar jämföras mot data från ett verkligt fordon somutförde samma prov.Från verieringen har slutsatsen dragits att modellen uppfyllde målen med projektet. Målen var, att den slutliga simuleringsmodellen visar ett liknande beteende som en växellåda i ett verkligen fordon. Växlingar och låsning/upplåsning hos momentomvandlareninträande vid ungefär samma situationer i simuleringarna som i provningen med det verkligafordonet.

Uppsala University has been spending a lot of time and resources in developing wave energy converters. In the test site of Lysekil, a full-scale point absorbing buoy with its associated components have been tested. From the test, various new information were discovered. To improve energy generation from wave motion, new ideas and machineries need to be developed. The linear generator deployed with the point absorbing buoy needs a better power absorbing torque converter. Therefore, this master thesis focuses on a novel twin generator torque converter that will convert the mechanical motions of the buoy in a wave climate to electrical power to a load. The prototype design needs to be validated by simulation before a physical model can be built. By using COMSOL Multiphysics® software, a regular wave is simulated by linear potential flow theory. The forces a buoy will experience in a wave climate are calculated and then used to rotate the prototype generator. The prototype generator is also simulated in COMSOL using the ‘Rotating Machineries’ physics. Power extracted from the generator is then observed and discussed.

In recent years many companies have investigated the use of hybrid technology due to the potential of increasing the driveline’s efficiency and thus reducing fuel consumption. Previous studies show that hydraulic hybrid technology can be favourable to use in construction machinery such as wheel loaders, which often operate in repetitive drive cycles and have high transient power demands. Parallel as well as Series hybrid configurations are both found suitable for wheel loader applications as the hybrid configurations can decrease the dependency on the torque converter. This project has investigated a novel hydraulic hybrid concept which utilizes the wheel loaders auxiliary pump as a supplement to enable both Series and Parallel hybrid operation. Impact of accumulator sizes has also been investigated, for which smaller accumulator sizes resembles a hydrostatic transmission. The hybrid concept has been evaluated by developing a wheel loader simulation model and a control system based on a rule-based energy management strategy. Simulation results indicate improved energy efficiency of up to 18.80 % for the Combined hybrid. Moreover, the accumulator sizes prove to have less impact on the energy efficiency. A hybrid system with decreased accumulator sizes shows improved energy efficiency of up to 16.40 %.