BorgWarner Powerdrive Systems is constantly developing the performance of wet clutches used in passenger car all-wheel drive systems. The Haldex limited slip coupling, LSC, is the trade name of the all-wheel drive system sold and developed by BorgWarner Powerdrive Systems. In a primary front-wheel driven vehicle, the Haldex LSC can transfer torque to the rear axle based on sensor input with full electronic control and can thus work seamlessly together with other systems such as traction and stability control. In the design of such an all-wheel drive system; it is critical to avoid issues with drive line vibrations as well as the accompanying noise generation. This is a complex issue and even though the goal is to avoid these problems, they may still occur to a certain degree. BorgWarner now wants to investigate whether changes in the friction disc quality may affect the occurrence of vibrations. The friction disc quality could e.g. be described in terms of variations in height, material composition, material porosity and Young's modulus with the variations distributed around the circumferential of the friction disc. This study is however limited to investigate if a difference in height could be the cause of drive line vibrations. The goal is to determine if there is a correlation between a shifting thickness around the circumferential of the friction disc and the occurrence of vibrations. With the help from RISE Sicomp and their 3D-scanner it was possible to determine the difference in height around the circumference of the disc. The discs was scanned and then analyzed with the help of GOM-software. When the height was measured around the disc they were exposed to a run-in, this with the use of an LSC test rig. This way it is possible to see how the friction characteristics changes while it is being used and to later see if the height difference has changed. All this to see the correlation between the difference in height around the disc and the friction characteristics. A micro tomography scanner at LTU was used to section through the disc. It uses x-ray and makes it possible to look at sections all through the disc to see if there is a difference in the strucure of certain areas. If one pillow is more porous then another one. Based solely on the tomography test it is hard explaining the difference in Young’s modulus, the result showed little to none difference between different areas of the disc. With the help from 3D-scanning it has been shown that there is in fact a height difference. That difference becomes smaller with time when used, this due to the wearing of the highest area being greater than that of a lower area. The run-in seems to always have a positive result on the disc. Friction measurements during run-in showed that also a disc with small differences in height could display unfavorable friction characteristics. This would imply that the height difference matters but is not the only contributing factor to vibrations. Even though the difference in thickness of the friction disc has shown to contribute to vibrations, there are still factors that remains unclear. If the height would have been the only factor the friction measurements would support this more than what the actual case is. The other factors need further examination.

Thesis (M.Eng.(Mechanical and Aeronautical Engineering))--University of Pretoria, 2008. / Includes bibliographical references.

In 2004, students at the University of Guelph designed and constructed an all-wheel-drive Formula SAE vehicle for competition. It utilized an electronically-controlled, hydraulic-actuated limited slip center coupling from Haldex Traction Ltd, to transfer torque to the front wheels. The initial control system design was not comprehensively conceived, so there was a need for a thoroughly developed control system for the all-wheel-drive actuator augmented with commonly available sensors and a low cost controller. This thesis presents a novel all-wheel-drive active torque transfer controller using a neural network estimated slip angle velocity. This controller specifically targets a racing vehicle by allowing rapid direction changes for maneuverability but damping slip angle changes for increased controllability. The slip angle velocity estimate was able to track the actual simulated value it was trained against with excellent phase matching but with some offsets and phantom spikes. Using the estimated slip angle velocity for control realized smooth control output, excellent stability, and a fast turn-in yaw response on par with rear-wheel-drive configurations. A full vehicle simulation with software-in-the-loop testing for control software was also developed to aid the system design process and avoid vehicle run time for tuning. This design flow should significantly decrease development time for controls algorithm work and help increase innovation within the team.

The thesis is performed in order to improve the curvic coupled engagement of a dog clutch situated in the transfer case of a truck. The dog clutch is used to engage the so called all-wheel-drive system of the truck. If the driver tries to engage the all-wheel-drive when truck’s rear wheels already skid, due to a slippery surface a relative rotational speed in the dog clutch will occur. This relative rotational speed will cause the dog clutch to bounce back of itself before engagement, or to not engage at all. The dog clutch has been redesigned to prevent this. Dynamic simulations using MD Adams have been made for the existing model, for the models created in previous works, and for the new model in order to figure out which of them will show the most stable engagement, at high relative rotational speed. The implemented simulations show that better results can be obtained. Separation into two parts of the disc pushed by the fork, shows that dog clutch’s engagement is faster and more stable, comparing to the original model and the other created models. The new model shows better coupling in the whole range of the relative rotational speed from 50 up to 120rpm.

Normally the trucks with four wheel drive option will be running in rear wheel drives and the front wheels will be rotating freely. In extreme tough driving conditions, the risk for getting stopped or slipping the rear wheels in mud is high. When the driver tries to engage the four wheel drive option and due to the difference in relative rotational speed of the dog clutch parts, there is a risk for slipping off or bouncing back of the dog clutch. After studying the importance of gear geometry and a few parameters, the team ended up with a new design and the performance of the design found satisfactory when simulated in MSC ADAMS.

This thesis consists of two parts. The first one contains a research about different kinds of divorces in tractors. There is also a description of a modelling in MATLAB, Simulink and Stateflow programs. The second part focuses on designing an algorithm of an automatic locking differential and connection front-wheel drive and its testing on a model of tractor. Furthermore the thesis solves an implementation process of the algorithm into the control unit.

<p>The Swedish Military Defence is about to make a large reorganization. Surplus, everything from tanks to personal underwear, enough to equip 800,000 soldiers will be destroyed or sold to the highest bidder. This thesis is a discourse analysis about the argumentation in media between the Military and the enthusiast, who are interested in military vehicles and military surplus.</p> / <p>Uppsatsen är en kartläggning och diskursanalys av den argumentation som förekommit i den mediala debatten rörande den svenska Försvarsmaktens avveckling av överskott. Morgondagens försvar ska vara baserat på kvalité istället för kvantitet. Från att ha haft ett försvar som omfattat omkring 800 000 personer under vapen i händelse av ofred ska det nya försvaret skäras ned till att omfatta omkring 200 000 personer. En mängd materiel, allt från stridsvagnar och underkläder, blir således överflödig. Försvarsmakten skall fram till utgången av 2004 ha genomfört omorganisationen. Tillvägagångssättet att avveckla överskottet varierar, destruktion, försäljning och som bistånd är exempel på avvecklingsalternativ. De olika tillvägagångssätten har fått kritik från olika aktörer som deltagit i debatten. Det opinionen reagerat på är att, i många fall, helt fungerande och ny materiel destruerats eller så har kritik riktats mot de olika försäljningsförfarandena som Försvarsmakten tillämpat. Uppsatsen undersöker aktörernas argumentering i debatten och försöker att analysera varför argumenteringen ser ut som den gör. </p>

The Swedish Military Defence is about to make a large reorganization. Surplus, everything from tanks to personal underwear, enough to equip 800,000 soldiers will be destroyed or sold to the highest bidder. This thesis is a discourse analysis about the argumentation in media between the Military and the enthusiast, who are interested in military vehicles and military surplus. / Uppsatsen är en kartläggning och diskursanalys av den argumentation som förekommit i den mediala debatten rörande den svenska Försvarsmaktens avveckling av överskott. Morgondagens försvar ska vara baserat på kvalité istället för kvantitet. Från att ha haft ett försvar som omfattat omkring 800 000 personer under vapen i händelse av ofred ska det nya försvaret skäras ned till att omfatta omkring 200 000 personer. En mängd materiel, allt från stridsvagnar och underkläder, blir således överflödig. Försvarsmakten skall fram till utgången av 2004 ha genomfört omorganisationen. Tillvägagångssättet att avveckla överskottet varierar, destruktion, försäljning och som bistånd är exempel på avvecklingsalternativ. De olika tillvägagångssätten har fått kritik från olika aktörer som deltagit i debatten. Det opinionen reagerat på är att, i många fall, helt fungerande och ny materiel destruerats eller så har kritik riktats mot de olika försäljningsförfarandena som Försvarsmakten tillämpat. Uppsatsen undersöker aktörernas argumentering i debatten och försöker att analysera varför argumenteringen ser ut som den gör.

Safety, performance and driving comforts are given high importance while developing modern day cars. All-Wheel Drive vehicles are exactly designed to fulfill such requirements. In modern times, human concern towards depleting fossil fuels and cognizance of ecological issues have led to new innovations in the field of Automotive engineering. One such outcome of the above process is the birth of electrical hybrid vehicles. The product under investigation is a combination of all wheel drive and hybrid system. A superior fuel economy can be achieved using hybrid system and optimized vehicle dynamic forces are accomplished by torque vectoring action which in turn provides All-Wheel Drive capabilities. Heat generation is inevitable whenever there is a conversion of energy from one form into another. In this master thesis investigation, a thermal simulation model for the product is built using 1D simulation tool AMESim and validation is done against the vehicle driving test data. AMESim tool was chosen for its proven track record related to vehicle thermal management. The vehicle CAN data are handled in MATLAB. In a nutshell, Simulation model accounts for heat generation sources, oil flow paths, power loss modeling and heat transfer phenomena. The final simulation model should be able to predict the transient temperature evolution in the rear drive when the speed and torque of motor is supplied as input. This simulation model can efficiently predict temperature patterns at various locations such as casing, motor inner parts as well as coolant at different places. Various driving cases were tried as input including harsh (high torque, low speed) ones. Simulation models like this helps Engineers in trying out new cooling strategies. Flow path optimization, flow rate, convection area, coolant pump controlling etc are the few variables worth mentioning in this regard.

The thesis is carried out in order to improve the transfer case in trucks with all-wheel-drive. When the truck loses traction at the rear wheels, due to slippery surfaces, wheel-spin occurs. If the driver engages the all-wheel-drive at a point where traction already has been lost, a relative rotational speed in the dog clutch will occur. If this relative speed is too high the dog clutch bounces of itself before coupling or it does not couple at all. To avoid this problem, the geometry of the teeth is modified. FE simulations are done for the existing model as well as for all the new models in order to find out which of them can handle the highest relative rotational speed. The results show that the original model is not the best one. Simple modifications of the teeth’s chamfer distance and chamfer angle shows that the dog clutch can handle up to 120 rpm of relative rotational speed whereas the original model only handles 50 rpm. / Examensarbetet är utfört för att försöka förbättra inkopplingen av allhjulsdrift på lastbilar. När en lastbil kör på halt eller löst väglag kan hjulspinn uppstå vid bakhjulen. Om föraren kopplar in allhjulsdriften när hjulen börjat slira uppstår en relativ rotationshastighet mellan halvorna i klokopplingen. Om denna relativa rotationshastighet är för hög kommer halvorna i kopplingen studsa mot varandra innan de kopplas ihop eller inte koppla ihop alls. För att undvika detta problem har klokopplingens tandgeometri modifierats. FE simuleringar är gjorda på den ursprungliga modellen samt alla nya modeller för att ta reda på vilken som kopplar vid högst relativa rotationshastighet. Resultaten visar att förbättringar kan göras. Enkla modifieringar på avfasningarnas avstånd och vinklar visar att klokopplingen kan klara upp till 120 rpm i relativ rotationshastighet jämfört med den ursprungliga modellen som endast klarar 50 rpm.