In an effort to improve the safety and road-holding capabilities of vehicles, manufacturers have begun a trend toward increasing vehicle body roll resistance by introducing stiffer roll-stabilizer bars. In this study vehicle suspension and road surface models are developed to investigate the effects of such stabilizer bars on ride quality. The purpose of the research is to determine the need for further studies in the area of active roll stabilizer systems. Two dynamic vehicle models are developed: the simplified front-car model and the full-vehicle-body three-degree-of-freedom model. The effects of the stabilizer bars on ride quality are then studied through the use of asymmetric road surface profiles. Discrete, periodic, and random road surface models are used to excite the vehicle models. Emphasis is placed on random road models and predicting the vehicle response using spectral input/output techniques.

<p> This dissertation describes a methodology for the vehicle dynamics control of a wheel motored vehicle. All theory is developed assuming that the driver has control of the front wheel steering angle, and that wheel torque is solely generated by independent wheel motors at each corner of the vehicle. Theoretical work is presented for the general case with four independent wheel motors, but can be easily reduced to a situation with only two wheel motors. Indeed, all theory developed in this work is evaluated experimentally on a production automobile converted to be driven by two independent rear wheel motors. </p><p> As opposed to directly allocating wheel torques, the proposed philosophy operates in the slip-ratio domain. Doing so helps to prevent excessive tire saturation and allows the system to adapt to changing road surfaces. To that end, this dissertation first proposes a method of estimating slip-ratio utilizing only sensors currently available on modern automobiles. A slip-ratio controller is then developed approximating the disturbance observer structure. This allows the controller to be robust to changing road surface and as a byproduct provide an accurate estimate of longitudinal tire force. Combining the estimated longitudinal tire force with the estimated slip-ratio it is then possible to ascertain some degree of tire saturation. With this in mind, an optimal control allocation problem is proposed which attempts to achieve the desired vehicle dynamics while at the same time minimizing tire saturation. </p><p> It is shown experimentally that the proposed control methodology effectively achieves desired vehicle dynamics. In addition, the system adapts its behavior to changing road surfaces resulting in optimal performance regardless of operating conditions.</p>

Innovative clutching mechanisms for hybrid automotive transmissions that yield low losses, while still satisfying the conflicting requirements of compactness, quick response, and high power density are explored in this thesis. Moreover, a systematic approach to automotive-transmission clutch design is proposed. The goal is to provide a complementary tool to aid the designer's judgment. The various design variants chosen serve two purposes, to demonstrate the foundation and to showcase approaches and solutions to specific problems that have a direct application in transmission design. The analysis of design variants goes into sufficient depth to be useful to both practicing automotive design engineers and academics.The phenomenon of "spin loss" is well known in the automotive industry, for it affects all transmissions. One energy sink identified in this regard lies in traditional wet clutches and brakes, wherein an open clutch or, correspondingly, an open brake, creates drag on the transmission because of the oil churning around and between the rotating friction plates. A second source of spin loss, or energy sink, is of electromagnetic origin, as it occurs by virtue of spinning inactive motors that carry permanent magnets. Apart from spin losses, the hydraulic actuation of clutches and brakes suffers from head losses. Seals, pumps and valves incur leakages that cause energy loss.Using the techniques outlined in this thesis, two separate novel clutch variants are demonstrated to improve clutch and brake technology. One variant, the electromechanical clutch actuator, is based on a high-performance screw joint with a built-in locking mechanism. The screw joint was tested with two sub-variants, namely, a lead screw and a ball screw. One prototype of each of the two sub-variants was installed on a testbed, to mimic the installation of the actuator in place of the corresponding hydraulic components. To better reflect the elastostatic behaviour of the clutch disk assembly, a new model for its stiffness as a hardening spring was formulated. Proof-of-concept tests of both sub-variants, lead and ball screws, demonstrated their feasibility.The second variant, the electromagnetic dog clutch, is directly aimed at minimizing spin and hydraulic actuation losses for clutched electric motors, wherein the motor is connected to a clutch. The system includes a unique contactless electromagnetic synchronizer and a synchronizing sleeve with dog teeth on the input and output components. The design study, focused on the electromagnetic part, strives to reduce clutch slip and control torque. The novel design features claw-like stator and salient rotor poles with good machinability within a restrictive design volume. A complete design analysis with physical proof-of-concept testing was conducted.Reducing "spin-loss" in transmission assemblies will improve system efficiency and yield better fuel economy. The technologicalimpact will benefit not only the user, who will obtain more mileage for her or his dollar, but also the environment. / Dans cette thèse sont étudiés des mécanismes innovants d'embrayage pour transmissions automobiles hybrides qui n'engendrent que de faibles pertes, tout en satisfaisant les besoins parfois conflictives de compacité, de haute vitesse de réaction et de haute densité d'énergie. Une approche systématique de la conception de transmissions automobiles est proposée, dont l'objectif est d'offrir un outil complémentaire au jugement du concepteur. Les divers alternatives choisises servent à présenter les concepts fondamentaux, ainsi qu'à mettre en valeur les différentes approches et solutions à des problèmes spécifiques qui ont une application directe dans le domaine des conceptions de transmissions. L'analyse d'alternatives de conception va suffisamment en profondeur pour être utile à la fois aux ingénieurs de conception automobile et aux théoriciens.Le phénomène de pertes d'énergie cinétique de rotation (PECR) est bien connu dans l'industrie automobile, car cela affecte toutes les transmissions. Un puits d'énergie mis en évidence à ce propos concerne les embrayages et freins traditionnels à fluides, pour lesquels un embrayage ouvert ou un frein ouvert, crée une traînée dans la transmission parce que l'huile tourbillonne autour et dans les plaques tournantes de friction. Un second puits d'énergie est d'origine électromagnétique, car générée par la rotation de moteurs inactifs contenant des aimants permanents. Hormis le PECR, l'actionnement hydraulique d'embrayages ou de freins entraîne des pertes de charges. Les joints, pompes et valves encourent des fuites qui engendrent de puits d'énergie.En utilisant les techniques mises en avant dans cette thèse, deux nouvelles alternatives d'embrayages démontrent leurs capacités à améliorer les technologies des freins et des embrayages. L'une de ces alternatives, l'actionneur {\em électromécanique d'embrayage}, est basée sur une liaison à vis et dispose d'un mécanisme intégré de verrouillage. La liaison à vis a été testée au travers de deux sous-alternatives, à savoir une vis à filet trapézoïdal et une vis à billes. Un prototype de chacune des alternatives a été installé sur un banc d'essai, afin de reproduire l'installation de l'actionneur en lieu et place des composants hydrauliques correspondants. Pour mieux refléter le comportement élastostatique de l'assemblage des disques d'embrayage, un nouveau modèle de sa raideur, assimilée à un ressort durcissant, a été formulé. Des tests de preuve de concept des deux variantes, vis à filet trapézoïdal et vis à billes, ont montré leur faisabilité.La seconde variante, l'embrayage électromagnétique à interférence, est directement utilisable pour minimiser les pertes en rotation et en actionnement hydraulique pour les moteurs électriques à embrayage, pour lesquels un moteur est connecté à un embrayage. Le système inclut un unique synchronisateur et des bagues de synchronisation avec des dents-de-chien sur les composants en entrée et en sortie. Le travail de conception a été concentré sur la partie électromagnétique, qui essaie de réduire le glissement de l'embrayage et le couple de commande. Le nouveau système conception est doté d'un stator en forme de griffes et des pôles de rotor saillants faciles à usiner et à installer dans un espace restreint dans la voiture. Une étude complète de conception avec des tests concrets de preuve de concept a été accomplie.Rééduire le PECR dans les assemblages de transmissions améliorera l'efficience du système et mènera à davantage d'économie de carburant. L'impact technologique sera ainsi bénéfique non seulement pour l'utilisateur, qui profitera d'un kilométrage plus élevé pour son argent, mais aussi pour l'environnement.

The effects of swirling flow and spark locations on the specific rate of growth of flame area, the flame speed and the convection velocity are investigated experimentally in a constant volume vessel near the lean misfire limit for an equivalence ratio of 0.645 using the shadowgraph technique. The circular and the elliptical models are used as flame contours to calculate the flame speed and the convection velocity. The circular model indicates that the flame speed decreases as the swirl flow decays and as the spark location is moved towards the center of the combustion chamber. The modified elliptical model shows the same result for the average flame speed $S\sb{ws}$. Both models show an overlap in convection velocity when comparison is made at a given spark location for different swirl levels because of cyclic variation; even though the average is higher for higher swirl level. The specific rate of growth of flame area (${1\over A}{dA\over dt}$) is obtained using three models for flame area A: (i) 2-D flame area $A\sb{f}$ measured from the photographs, (ii) spherical flame geometry model, and (iii) ellipsoidal geometry model. The stretch factor $K=({\delta\sb{l}\over u\sb{l}}) ({1\over A}{dA\over dt})$ at 0.5 ms from ignition time for the 2-D and the spherical models at ${r\over R}=0.68$ was within the range 0.63-0.97 and at ${r\over R}=0.55$ was within the range 0.5-0.59. The stretch factor for the ellipsoidal model at ${r\over R}=0.68$ was within the range 0.53-1.05 and at ${r\over R}=0.55$ was within the range 0.46-0.53. All three models for flame area indicate that the specific rate of growth of flame area and stretch factor at 0.5 ms from ignition time decrease as the swirl flow decays and as the spark location approaches the center of the combustion chamber.

Experimental measurements and model predictions of ignition delay times for single component and two-component liquid fuels are presented. The methodology used is the suspended-droplet/moving-furnace technique, in which a droplet of fuel is suspended from the tip of a thin quartz fibre. A preheated electric furnace moves towards and encompasses the droplet locality, producing a sudden rise in ambient temperature, and thus initiating the ignition process. The entire apparatus is enclosed in a pressure vessel and is remotely operated. Data were collected for pressures up to 18 atm absolute and in a temperature range of 773 K to 973 K. Fuels tested comprised n-paraffins (decane, dodecane, and hexadecane), aromatics (mesitylene, o-xylene, and isobutylbenzene) and a cycloparaffin (decalin), as well as selected binary combinations: n-decane/n-dodecane, n-dodecane/n-hexadecane, n-decane/decalin, n-decane/isobutylbenzene, n-decane/mesitylene, and n-decane/o-xylene. Paraffin measurements at low pressures and high temperature revealed a monotonic decrease in ignition times with increasing pressure. However, higher pressure ignitions at lower temperatures showed more complex behaviour by the measurement of two or "twinned" ignition times for the same pressure and temperature condition, indicating a change in reaction mechanism, possibly from one-stage to two-stage ignition. Aromatic fuels did not show "twinned" ignition time behaviour and responded with a slight increase in ignition times with increasing pressure, owing to a weaker reaction rate dependence on pressure. The cycloparaffin behaved analogously to the n-paraffin family. The behaviour of mixtures was largely controlled by the more volatile component. (Abstract shortened by UMI.)

No description available.

This work deals with the problem of determining the tire-road interaction forces for vehicle dynamic simulations. The work is an attempt to develope a numerical scheme that is universally applicable to all possible running conditions. The tire-road contact patch is approximated as a two-dimensional array of nodal points. Properties such as distribution of normal pressure, deflection and stresses over the contact patch are expressed as sets of the respective nodal values rather than analytical functions. Such a representation enables the treatment of any arbitrary, two-dimensional variation of contact patch properties. The representation of non-rectangular contact patch shapes and trapezoidal pressure distributions is also discussed. For steady state running conditions the performance of the scheme is compared with that of an existing analytical model. The applicability of the scheme to transient running conditions is also shown.

No description available.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2009. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3631. Adviser: Dimitrios C. Kyritsis. Includes bibliographical references (leaves 144-149) Available on microfilm from Pro Quest Information and Learning.

The accuracy and precision of catalytic converter analysis using conventional analytical methodology such as fire assay, x-ray fluorescence, atomic absorption and ICP-AES are typically in the range of ±7-10% RSD. Due to the high cost of noble metals, methods of analysis with increased accuracy and precision are desired to evaluate the loading of noble metals onto converter bricks. The investigations described in this work have resulted in a better understanding of many of the inherent problems and have contributed new approaches for sample dissolution and analysis using array detector based Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). These methods are shown to be accurate and precise for the analysis of Pt, Pd, and Rh in catalytic converters. Catalytic converters are difficult to dissolve by conventional acid methodology. While carius, tubes have previously been employed to dissolve small weights of sample, complete dissolution of increased amounts of sample, as needed for high precision ICP-AES analysis, has been hindered by the insufficient oxidation potential of the acids in the carius tube. In this work, the addition of ferric chloride is shown to increase the dissolving power of the carius tube method and specifically targets Pt, Pd and Rh for dissolution. Simultaneous collection of analyte wavelengths and simultaneous background correction, as performed with multichannel array detector ICP-AES instrumentation, have enhanced sensitivity and precision in catalytic converter analysis when compared to single channel instrumentation. The studies described within this dissertation demonstrate that flicker noise has been effectively eliminated through the use of multichannel array based ICP-AES instrumentation. With proper line selection and the use of the high-resolution system, Pt, Pd and Rh in catalytic converters can be analyzed with precision of 1-1.5%. ICP-AES accuracy has been confirmed through isotope dilution ICP-MS employing new methodology to avoid Zr isobaric interferences.