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General Motors introduced a family of small front wheel drive six speed automatic transmissions for the 2008 model year. The family currently has two variants: 6T40 and 6T45, which cover a range of vehicles from small & compact cars to small SUVs and handle engines torque capacities up to 240 Nm Gas(280 Nm Diesel) & 315 Nm Gas (380 Nm Diesel) respectively. The 6T40/45 transmissions replace GM traditional four speed automatic wrap around transmissions 4T40/45. The wrap around transmissions have Torque Converter, Pump & Controls on the engine axis and the rest of the transmission content on the output axis. The 6T40/45 have an on-axis architecture with majority of the transmission content on the engine axis and final drive & differential on the output axis. The 4T40/45 have input chain transfer whereas the 6T40/45 have an output chain transfer.

Two-stage turbochargers are a recent solution to improve engine performance, reducing the turbo-lag phenomenon and improving the matching. However, the definition of the control system is particularly complex, as the presence of two turbochargers that can be in part operated independently requires effort in terms of analysis and optimization. This work documents a characterization study of two-stage turbocharger systems. The study relies on a mean-value model of a Diesel engine equipped with a two-stage turbocharger, validated on experimental data. The turbocharger is characterized by a VGT actuator and a bypass valve (BPV), both located on the high-pressure turbine. This model structure is representative of a “virtual engine”, which can be effectively utilized for applications related to analysis and control. Using this tool, a complete characterization was conducted considering key operating conditions representative of FTP driving cycle operations.

Architecture exploration could benefit from some early results of a safety analysis process. Typically, classical system safety analysis techniques such as Fault tree analysis (FTA) are performed after the design is completed. We propose an approach for an early safety assessment to improve the design and also shorten the design cycle time. A quick assessment to determine the safety figure of merit of the intended architecture expressed as a parametric expression can be used to determine the overall acceptability of the architecture. The result from a quick assessment of the system safety could be used as a means to explore system trade-offs in reliability and redundancy at the highest design levels.

We investigate and analyze the concept of “missed detection” and its application to the design of architectures that integrate multiple safety/mission critical functions. The analysis is based on considering different design alternatives with varying levels of missed fault detection of the components constituting the functions or subsystems. The overall system reliability and availability in a fault tolerant architecture relies as heavily on the ability to detect a fault as it does on being able to prevent a fault as one would attempt by having multiple levels of redundancy and/or improved reliability of the components in such an architecture. In short, the safety of a particular architecture depends not only on component reliability, and fault tolerance, expressed as redundancy, but also on fault detectability.

We investigate and analyze the concept of “shared redundancy” and its application to the design of architectures that integrate multiple safety/mission critical functions or subsystems. The analysis is based on considering different design alternatives with varying levels of physical redundancy of the components constituting the functions or subsystems. Under a set of assumptions, we show that the overall system reliability and availability in a shared redundancy based architecture can be improved without increasing the levels of physical redundancy for the components employed at the subsystem level. However, such an improvement will be limited by the component(s) with the minimal level of redundancy.

A wet multi-plate clutch, designated as the “starting clutch”, and a two-speed simple planetary gearset are used to replace the torque converter in the 4T60-E automatic transmission in order to study the potential improvement of vehicle fuel economy without sacrificing 0 - 60 mph acceleration performance. The starting clutch and the two-speed simple planetary gearset are designed to fit in the torque converter compartment. This paper describes the modified five-speed 4T60-E starting clutch automatic transmission system and provides vehicle test results to demonstrate its fuel economy and 0-60 mph performance potential.

A wet multi-plate clutch, designated as the “starting clutch”, is used to replace the torque converter in the automatic transmission in order to improve vehicle fuel economy. The transmission ratio spread must be increased to compensate for the torque multiplication of the torque converter and avoid penalizing the 0-60 mph acceleration performance. The main challenge of this concept is the control of the starting clutch to ensure acceptable vehicle drivability. This paper describes the system of a five-speed starting clutch automatic transmission vehicle and shows vehicle test results. Vehicle test data show that (i) the fuel economy benefit of the starting clutch is significant, and (ii) a starting clutch transmission can be designed to equal or better the 0-60 mph acceleration performance of a torque converter transmission by proper selection of the gear ratios.

By-wire systems have the potential of augmenting the normal capabilities of human drivers as well as serving as enablers for emerging safety technologies. To achieve these features, these systems must be carefully designed, analyzed, and verified for safety because they are new, complex, and potentially exhibit new and different failure modes and effects. Duplication may be required to ensure that safety margins are met in the presence of faults. Full duplication of every system may not lead to a cost effective implementation, especially if multiple independent by-wire systems are placed on a single vehicle. Other architectural approaches for the integration of by-wire systems need to be considered and analyzed. These architectures should meet if not exceed the safety requirements while providing a more cost effective implementation than a fully duplicated architecture.

The development and application of a traction control Kodiak and GMC TopKick are explained. Most traction systems use engine management to enable traction control, while the adaptive braking system can provide traction assist for either gas or Diesel powered vehicles from 14,000 lbs. to 33,000 lbs. GVW. The performance driven criteria that established the design requirements and the development of a new product to meet these objectives are discussed. Both the vehicle manufacturer and the traction controller supplier provided these criteria. The basic ABS and traction control hydraulic schematics will be described as they apply to the vehicles. The results of the development program will be compared to the criteria used to establish the goals, and the benefits of the traction control system will be discussed.

By using descriptive charts and graphs, this report provides an analysis of the IDB-C network at the Subsystem level and at the vehicle level, using data comparison between modeling and simulation of the network and measurement and analysis on physical systems.

This paper describes the recent efforts on developing an automotive climate control system throughout integrating an electrically-controlled variable capacity scroll compressor with a fuzzy logic control-based refrigerant flow management. Applying electrically-controlled variable capacity compressor technology to climate control systems has a significant impact on improving vehicle fuel economy, achieving higher passenger comfort level, and extending air and refrigerant temperature controllability as well. In this regard, it is very important for automotive climate control engineers to layout a system-level temperature control strategy so that the operation of variable capacity compressor can be optimized through integrating the component control schemes into the system-level temperature control. Electronically controlled expansion devices have become widely available in automotive air conditioning (A/C) systems for the future vehicle applications(1, 2, 3 and 4).

The complexity of designing and implementing a vehicle electrical control system for ultra fuel-efficient hybrid vehicles is significantly greater than that of a conventional vehicle. To quickly demonstrate and iterate capabilities of these vehicles, an efficient and rapid means for developing requirements, mapping these into an electrical control and communications architecture, and developing prototype systems is needed. The General Motors Precept concept vehicle is an example of an energy- efficient vehicular control system developed using a "requirements to software'' development process and electronic controller infrastructure that demonstrates these attributes. The Precept is General Motors Corporation's technology demonstration concept vehicle developed to address General Motors Corporation's commitment to the Partnership for a New Generation (PNGV) program.

The purpose of the Cadillac DeVille Night Vision System is to provide drivers with visual information beyond with the range of their headlamps. It can also help drivers see beyond the glare of oncoming vehicle’s headlamps. With increased visual range the driver may have more time to react to potentially dangerous situations. The system consists of a thermal imaging camera, a head-up display, and image controls. The camera senses temperature differences of objects in the road scene ahead and creates a thermal image of the scene. The head-up display projects this image onto the windshield creating a virtual image that appears at the front edge of the vehicle’s hood just below the driver’s line of sight. This paper will describe the system requirements and parameters of the 2000 Cadillac DeVille Night Vision system.

This paper describes the performance attributes of the all-new front and rear SLA (short-long arm) suspensions, steering system, and tires of the 1997 Corvette. The process by which these subsystem attributes flowed down from vehicle-level requirements for ride and handling performance is briefly described. Additionally, where applicable, specific subsystem attributes are rationalized back to a corresponding vehicle-level performance requirement. Suspension kinematic and compliance characteristics are described and contrasted to those of the previous generation (1984 to 1996 Model Year) Corvette. Both synthesis/analysis activities as well as mule-level vehicle development work are cited for their roles in mapping out specific subsystem attributes and related vehicle performance.

This paper describes the design, synthesis-analysis and development of the unique vehicle structure architecture for the fifth generation Chevrolet Corvette, ‘C5’, which starts in the 1997 model year. The innovative structural layout of the ‘C5’ enables torsional rigidity in an open roof vehicle which exceeds that of all current production open roof vehicles by a wide margin. The first structural mode of the ‘C5’ in open roof configuration approaches typical values measured in similar size fixed roof vehicles. Extensive use of CAE and a systems methodology of benchmarking and requirements rolldown were employed to develop the ‘C5’ vehicle architecture. Simple computer models coupled with numerical optimization were used early in the design process to evaluate every design concept and alternative iteration for mass and structural efficiency.

This paper describes an absolute stability analysis of idle speed control systems. Current idle speed control systems make use of both spark advance and the idle air actuator to control engine speed for improved response relative to variations in the target idle speed due to load disturbances. The control system at idle can be presented by a multiple input multiple output (MIMO) model [1]. Control system design is usually done based on linear or linearized models [2,3,4]. However idle speed control systems are nonlinear because of the saturation of the actuators. This paper describes an application of the absolute stability theory to idle speed control systems with saturation of actuators.

It is known that the formability of tailored welded blanks depends on the welding set-up conditions. Little information is available on the correlation between the formability of welded blanks and weld set-up conditions. In this investigation, effects of mash seam welding parameters of weld current, weld force, material overlap and planish on formability performance of welded blanks are studied. The systematic design of experiments approach is used to identify the key weld parameters influencing the formability performance of welded blanks. It is found that high weld force decreases formability of welded blanks and high weld force coupled with a small material overlap results in very low forming limit of the weld zone. Weld current has little effect on formability of welded blanks and planishing significantly reduces it. Overall, the mash seam welded blanks produced with appropriate weld set-up conditions are robust with respect to formability.

A design of experiments is used to study the effect of laser weld parameters on formability of welded blanks for two different material combinations of cold rolled (bare) steel to cold rolled steel and cold rolled steel to hot dipped galvanized steel. Critical weld parameters influencing the formability of welded blanks are identified and the optimum weld set-up condition is obtained based on formability performance and consistency of formability for laser welded blanks. The results are applied to an automotive body side frame. The robustness of welded blank production is also assessed and the final welded set-up condition for the body side frame is obtained based on both the formability of welded blanks and the robustness of welded blank production. The body side frame is successfully made from the welded blanks with this final weld set-up condition.

This paper introduces for the first time a fully connectorized passive optical star for use with plastic optical fiber that addresses all automotive application requirements. A unique mixing element is presented that offers linear expandability, uniformity of insertion loss, and packaging flexibility. The star is constructed of all plastic molded components to make it low cost and produceable in high volume and is single-ended to facilitate vehicle integration. The star is connectorized to facilitate assembly into the vehicle power and signal distribution system.

Passive star networks have been shown to be the best architecture for high speed vehicle networks. This paper attempts to describe how problems in passive star networks can be diagnosed in the field. The potential physical layer failure modes for passive star networks are detailed, and a network test tool is described which is capable of determining whether a media fault exists and locating the position of that fault. The application of the test tool to potential failure modes is discussed.