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We propose a composite thermal model of the vehicle passenger compartment that can be used to predict and analyze thermal comfort of the occupants of a vehicle. Physical model is developed using heat flow in and out of the passenger compartment space, comprised of glasses, roof, seats, dashboard, etc. Use of a model under a wide variety of test conditions have shown high sensitivity of compartment air temperature to changes in the outside air temperature, solar heat load, temperature and mass flow of duct outlet air from the climate control system of a vehicle. Use of this model has subsequently reduced empiricism and extensive experimental tests for design and tuning of the automatic climate control system. Simulation of the model allowed several changes to the designs well before the prototype hardware is available.

This paper discusses an analytical technique for computing the failure rate of steel springs used in automotive part applications. Preliminary computations may be performed and used to predict spring failure rates quickly at a very early stage of a product development cycle and to establish program reliability impact before commitment. The analytical method is essentially a combination of various existing procedures that are logically sequenced to compute a spring probability of failure under various operational conditions. Fatigue life of a mechanical component can be computed from its S-N curve. For steels, the S-N curve can be approximated by formulae which describe the fatigue life as a function of its endurance limit and its alternating stress. Most springs in service are preloaded and the actual stress fluctuates about a mean level. In order to compute an equivalent alternating stress with zero mean, an analytical method based on the Goodman Diagram is used.

Since 1997, General Motors Body Manufacturing Engineering - Die Engineering Services (BME-DES) has been working jointly with our software vendor to develop and implement a parallel version of stamping simulation software for mass production analysis applications. The evolution of this technology and the insight gained through the implementation of DMP/MPP technology as well as performance benchmarks are discussed in this publication.

Historically, the long development time required to produce a new automobile has meant that the electronics in that vehicle might lag the state-of-the-art by several years. For traditional vehicle electronics, this was certainly an appropriate delay, ensuring through extensive testing and qualification that the quality and reliability of the electronic systems met rigorous standards. However, with the growing consumer-oriented electronics content in today's vehicles, it is becoming more difficult for the automotive manufacturers to meet consumers' expectations with older technology. Couple this with the fast-paced consumer product cycle, typically nine to eighteen and the result is increasing pressure on the vehicle manufacturers from after-market electronics suppliers, who can update their product lines as fast as the component manufacturers can produce new models.

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.

Fully Flexible Valve Actuation (FFVA) systems provide maximum flexibility to adjust lift profiles of engine intake and exhaust valves. A research grade electro-hydraulic servo valve based FFVA system was designed to be used with an engine in a test cell to precisely follow desired lift profiles. Repetitive control was chosen as the control strategy. Crank angle instead of time is used to trigger execution to ensure repeatability. A single control is used for different engine speeds even though the period for one revolution changes with engine speeds. The paper also discusses lift profile extension, instantaneous lift profile switching capability and built-in safety features.

The Auto/Steel Partnership established the Light Truck Frame Project Group in 1996 with two objectives: (a) to develop materials, design and fabrication knowledge that would enable the frames on North American OEM (original equipment manufacturer) light trucks to be reduced in weight, and (b) to improve corrosion resistance of frames on these vehicles, thereby allowing a reduction in the thickness of the components and a reduction in frame weight. To address the issues relating to corrosion, a subgroup of the Light Truck Frame Project Group was formed. The group comprised representatives from the North American automotive companies, test laboratories, frame manufacturers, and steel producers. As part of a comprehensive test program, the Corrosion Subgroup has completed tests on frame coatings. Using coated panels of a low carbon hot rolled and pickled steel sheet and two types of accelerated cyclic corrosion tests, seven frame coatings were tested for corrosion performance.

Electro-Motive Division of GM jointly with HRL Laboratories have developed a software tool, called TechPro, which assists in troubleshooting of diesel locomotives. The tool has been tested extensively in the field for the last two years. It has improved significantly the quality of diagnosis of locomotives. The tool is based on Graphical Probabilistic Models and Case Data Bases. We will discuss the design of the tool, its performance and will show its relevance to diagnosis of automobiles.

This report summarizes the methodology used in automotive industry for virtual evaluation of vehicle structural integrity under abusive load cases. In particular, the development of a nonlinear finite element (FE) centric approach is covered that is based on the functions implemented in ABAQUS (by ABAQUS Inc.). An overview is also given for comparative study of the ABAQUS capability with the existing ADAMS (MSC Software) based methods.

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).

In order to engineer Squeak & Rattle (S&R) free vehicles it is essential to develop an objective measurement method to compare and correlate with customer satisfaction and subjective S&R assessments. Three methods for exciting S&Rs -type surfaces. Excitation methods evaluated were road tests over S&R surfaces, road simulators, and direct body excitation (DBE). The principle of DBE involves using electromagnetic shakers to induce controlled, road-measured vibration into the body, bypassing the tire patch and suspension. DBE is a promising technology for making objective measurements because it is extremely quiet (test equipment noise does not mask S&Rs), while meeting other project goals. While DBE is limited in exposing S&Rs caused by body twist and suspension noises, advantages include higher frequency energy owing to electro-dynamic shakers, continuous random excitation, lower capital cost, mobility, and safety.

A gasoline direct injection fuel spray was observed using a fired, optical access, square cross-section single cylinder research engine and high-speed video imaging. Spray interaction with the piston is described qualitatively, and the results are compared with Computational Fluid Dynamics (CFD) simulation results using KIVA-3V version 2. CFD simulations predicted that within the operating window for stratified charge operation, between 1% and 4% of the injected fuel would remain on the piston as a liquid film, dependent primarily on piston temperature. The experimental results support the CFD simulations qualitatively, but the amount of fuel film remaining on the piston appears to be under-predicted. High-speed video footage shows a vigorous spray impingement on the piston crown, resulting in vapor production.

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.

This study examined whether the effect of subsidiary tasks on driving performance can be predicted from stationary (static) testing. Alternative methods for assessing the performance of drivers during their use of in-vehicle information systems were examined. These methods included static testing in stationary vehicles, as well as dynamic, on-road testing. The measures that were obtained from static tests were evaluated in terms of how well they could predict measures obtained from driving performance during on-road testing (which included concurrent use of secondary information systems). The results indicated that measures obtained in static test settings were highly correlated with corresponding measures obtained from on-road performance testing.

Commercially available software tools are widely used to assist in conducting life cycle inventory, life cycle assessment (LCA), life cycle impact analysis (LCIA), and design for the environment (DfE) studies. Five leading software tools, Boustead 4.2, GaBi 3.2, SimaPro 4.0, TEAM 3.0, and Toolkit, currently in use or under consideration by life cycle practitioners, were selected for testing, and a detailed evaluation scheme was used to evaluate the effectiveness of these tools for practical application in automotive life cycle studies. A consensus numerical score for each of 20 separate test criteria was assigned to each of the software packages under evaluation, and the total scores compared. On the basis of these scores, the authors chose GaBi version 3.2 as the LCA software package currently best suited for use by experienced life cycle practitioners in conducting environmental life cycle assessments in the automotive industry.

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.

Reducing the high cost of hardware testing with analytical methods has been highly accelerated in the automotive industry. This paper discusses an analytical model to simulate the driveline bending integrity test for the longitudinal 4WD-driveline configuration. The dynamic stresses produced in the adapter/transfer case and propeller shaft can be predicted analytically using this model. Particularly, when the 4WD powertrain experiences its structural bending during the operation speed and the propeller shaft experiences the critical whirl motion and its structural bending due to the inherent imbalance. For a 4WD-Powertrain application, the dynamic coupling effect of a flexible powertrain with a flexible propeller shaft is significant and demonstrated in this paper. Three major subsystems are modeled in this analytical model, namely the powertrain, the final rear drive, and the propeller shafts.

FIGURE 1 The 200 HP high performance 4.3L Vortec V6 engine has been developed to satisfy the need for a fuel efficient performance powerplant in the General Motors small truck platforms. Marketing requirements included strong low and mid range torque, relatively high specific power, smoothness and noise comparable to the best competitive six cylinder engines, excellent driveability, and a new technology image. Maintaining the 4.3L engine record of high reliability and customer satisfaction was an absolute requirement. Fuel economy and exhaust emission performance had to meet expected customer and legislated requirements in the mid 1990's.

In order to meet progressively stringent regulations on particulate emission from diesel engines, GM has developed and tested a variety of trap oxidizer systems over the years. A particulate trap system for a light duty diesel engine has been selected and developed based on this experience, with particular emphasis on production feasibility. The system components have been designed and developed in collaboration with potential suppliers, to the extent possible. The technical performance of this system has been demonstrated by successful system durability testing in the test cell and vehicle experience in computer controlled automatic operation mode. Although the system shows promise, its production readiness will require more development and extensive vehicle validation under all operating conditions.