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e-Thermal is a vehicle level thermal analysis tool developed by General Motors to simulate the transient performance of the entire vehicle HVAC and Powertrain cooling system. It is currently in widespread (global) use across GM. This paper discusses the details of the air-conditioning module of e-Thermal. Most of the literature available on transient modeling of the air conditioning systems is based on finite difference approach that require large simulation times. This has been overcome by appropriately modeling the components using Sinda/Fluint. The basic components of automotive air conditioning system, evaporator, condenser, compressor and expansion valve, are parametrically modeled in Sinda/Fluint. For each component, physical characteristics and performance data is collected in form of component data standards. This performance data is used to curve fit parameters that then reproduce the component performance.

This paper describes a vehicle-level simulation model for climate control and powertrain cooling developed and currently utilized at GM. The tool was developed in response to GM's need to speed vehicle development for HVAC and powertrain cooling to meet world-class program execution timing (18 to 24 month vehicle development cycles). At the same time the simulation tool had to complement GM's strategy to move additional engineering responsibility to its HVAC suppliers. This simulation tool called “e-Thermal” was quickly developed and currently is in widespread (global) use across GM. This paper describes GM's objectives and requirements for developing e-Thermal. The structure of the tool and the capabilities of the simulation tool modules (refrigeration, front end airflow, passenger compartment, engine, transmission, Interior air handling …) is introduced. Model data requirements and GM's strategy for acquiring component data are also described.

Vibration and sound radiation characteristics of bead-stiffened panels are investigated. Rectangular panels with different bead configurations are considered. The attention is focused on various design parameters, such as orientation, depth, and periodicity, and their effects on equivalent bending stiffness, modal density, radiation efficiency and sound transmission. A combined FEA-SEA approach is used to determine the response characteristics of panels across a broad frequency range. The details of the beads are represented in fine-meshed FEA models. Based on predicted surface velocities, Rayleigh integral is evaluated numerically to calculate the sound pressure, sound power and then the radiation efficiency of beaded panels. Analytical results are confirmed by comparing them with experimental measurements. In the experiments, the modal densities of the panels are inferred from averaged mechanical conductance.

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 boom test for the transverse engine with all wheel drive configuration on a front-wheel drive base (TFWD/AWD). Driveline boom caused by engine firing frequency that excites the bending mode of the propeller shaft becomes a noise and vibration issue for the design of TFWD/AWD driveline. The major source of vibrations and noise under the investigation in this paper is the dominant 3rd order engine torque pulse disturbance that excites the bending of the propeller shaft, the bending of the powertrain and possible the bending of the rear halfshaft. All other excitation sources in this powertrain for a 60° V6 engine with a pushrod type valvetrain are assessed and NVH issues are also considered in this transient dynamic model.

Damping treatments are widely used in passenger vehicles, but the knowledge of damping treatments is often fragmentary in the industry. In this study, vibro-acoustics behavior of a set of vehicle floor and dash panels with various types of damping treatments was investigated. Sound transmission loss, sound radiation efficiency as well as damping loss factor were measured. The damping treatments ranged from laminated steel construction (thin viscoelastic layer) and doubler plate construction (thick viscoelastic layer) to less structural “bake-on” damping and self-adhesive aluminum foil-backed damping treatments. In addition, the bare vehicle panels were tested as a baseline and the fully carpeted floor panel was tested as a reference. The test data were then examined together with analytical modeling of some of the test configurations. As expected, the study found that damping treatments add more than damping. They also add mass and change body panel stiffness.

The dash mat is one of the most important acoustic components in the vehicle for both powertrain noise and road noise attenuation. To optimize acoustic performance and mass requirements in the advanced development stage, analytical modeling is essential. The development of a detailed Statistical Energy Analysis (SEA) model of a dash mat is discussed in this paper. Modeling techniques and correlation with test are presented for two different production dash mat designs, a barrier-decoupler conventional system and a dual layer dissipative system without a mass barrier. The material properties and thickness distribution are used in the SEA model together with the geometry information of the dash panel. With the SEA model suitably correlated, trade-off studies are conducted to investigate the relationship between mass reduction of the barrier and change in decoupler thickness. The effects of air gaps are also considered in both modeling and testing.

The Advanced Engineering (AE) group within General Motors Powertrain (GMPT) develops next generation engines and transmissions for automotive and marine products. As a research organization, AE needs to prototype design ideas quickly and inexpensively. To this end, AE has embraced model-based development techniques and is currently investigating the benefits of software in-the-loop (SIL) testing. The underlying obstacle faced in developing a practical SIL system lays in the ability to integrate a plant model with sufficient fidelity together with target application software. ChiasTek worked with AE utilizing their CosiMate tool chain to eliminate these barriers and delivered a flexible SIL system simulation solution.

An accurate air flow rate model is critical for high-quality air-fuel ratio control in Spark-Ignition engines using a Three-Way-Catalyst. Emerging Variable Valve Timing technology complicates cylinder air charge estimation by increasing the number of independent variables. In our previous study (SAE 2004-01-3054), an Artificial Neural Network (ANN) has been used successfully to represent the air flow rate as a function of four independent variables: intake camshaft position, exhaust camshaft position, engine speed and intake manifold pressure. However, in more general terms the air flow rate also depends on ambient temperature and pressure, the latter being largely a function of altitude. With arbitrary cam phasing combinations, the ambient pressure effects in particular can be very complex. In this study, we propose using a separate neural network to compensate the effects of altitude on the air flow rate.

The emerging Variable Valve Timing (VVT) technology complicates the estimation of air flow rate because both intake and exhaust valve timings significantly affect engine's gas exchange and air flow rate. In this paper, we propose to use Artificial Neural Networks (ANN) to model the air flow rate through a 2.4 liter VVT engine with independent intake and exhaust camshaft phasers. The procedure for selecting the network architecture and size is combined with the appropriate training methodology to maximize accuracy and prevent overfitting. After completing the ANN training based on a large set of dynamometer test data, the multi-layer feedforward network demonstrates the ability to represent air flow rate accurately over a wide range of operating conditions. The ANN model is implemented in a vehicle with the same 2.4 L engine using a Rapid Prototype Controller.

A turbocharged version of the 2.4L engine has been developed by the Chrysler Group of DaimlerChrysler Corporation. This new engine is derived from the proven 2.4L 4-cylinder, with significant changes to achieve a durable, high performance package for the PT Cruiser vehicle. The package includes an integrated turbocharger / exhaust manifold, oil squirters for piston cooling, and numerous other upgrades to satisfy the demanding performance, emissions, and durability requirements unique to this powertrain. The purpose of this paper is to describe the mechanical changes to the base engine, the unique turbocharger configuration, and the new parts necessary to accommodate the higher output.

Transmission mounts are usually tested as an assembly and typically only translational stiffnesses are provided. The torsional stiffness of the assembly is traditionally estimated based on experience in load simulation and analysis. This paper presents a procedure to estimate the torsional stiffness of the transmission mount assembly by using the test data. The effects of the torsional stiffness on the simulation results are also discussed.

The US Environmental Protection Agency (EPA)’s heavy duty diesel emission standard was tightened beginning from 2007 with the introduction of ultra-low-sulfur diesel fuel. Most heavy duty diesel applications were required to equip Particulate Matter (PM) after-treatment systems to meet the new tighter, emission standard. Systems utilizing Diesel Oxidation Catalyst (DOC) and Catalyzed-Diesel Particulate Filter (DPF) are a mainstream of modern diesel PM after-treatment systems. To ensure appropriate performance of the system, periodic cleaning of the PM trapped in DPF by its oxidation (a process called “regeneration”) is necessary. As a result, of this regeneration, DOC’s and DPF’s can be exposed to hundreds of thermal cycles during their lifetime. Therefore, to understand the thermo-mechanical performance of the DOC and DPF is an essential issue to evaluate the durability of the system.

Crankshafts must be balanced statically and dynamically before being put into service. However, without pistons and connecting-rod assemblies, a non-symmetric crankshaft is not in dynamic balance. Therefore, it is necessary to apply equivalent ring-weights on each of the crankpins of the crankshaft when balancing it on a dynamic balancing machine. The value of the ring weight must be accurately determined, otherwise all advantages that are derived from balancing would be of no avail. This paper analytically examines the theoretical background of this problem. Formulas for calculating the ring weights are derived and presented. These formulas are applicable to a generic class of crankshafts of V-type engines with piston pin offset. Also, practical consideration, such as the design and manufacturing of these ring weights, the method of testing, and correction is addressed.

A new high output supercharged Northstar DOHC 4.4L V8 engine has been developed for new “V” series Cadillac performance models. The new engine combines the highest power rating of any production Cadillac engine to date with operating refinement uncommon at this power level. The new engine incorporates a high capacity airflow system including a unique GM Powertrain (GMPT) patented supercharger. The design integrates the intake manifold and supercharger (SC) into a supercharger module (SCM) supplied with throttle body (TB) and intercoolers (IC). The new engine architecture is based on the naturally aspirated (NA) rear wheel drive (RWD) engine released in 2004, but has been specifically designed and upgraded from the NA version for the greater structural and thermal loads that result from supercharging.

A new generation Northstar DOHC V8 engine has been developed for a new family of rear-wheel-drive (RWD) Cadillac vehicles. The new longitudinal engine architecture includes strategically selected technologies to enable a higher level of performance and refinement. These technologies include four-cam continuously variable valve timing, low restriction intake and exhaust manifolds and cylinder head ports, a steel crankshaft, electronic throttle control, and close-coupled catalysts. Additional design features beyond those required for RWD include optimized block ribbing, improved coolant flow, and a newly developed lubrication and ventilation system for high-speed operation and high lateral acceleration. This new design results in improved performance over the entire operating range, lower emissions, improved fuel economy, improved operating refinement, and reduced noise/vibration/harshness (NVH).

In September 2003, the Mercedes Car Group set another milestone by introducing the fifth generation of automatic transmissions developed and manufactured in-house since 1960. The world's first 7-speed automatic transmission 7G-TRONIC is featured in the Mercedes-Benz S, SL, CL and E-Classes with V8 gasoline engines. Deduced from the demands of the requirement specifications, the 5-speed automatic transmission was decisively improved; the result is a clear increase in spontaneity, agility, fuel economy, and driving comfort for the customer. And because of the harmony between the vehicle and its powertrain, excellent results in the areas of performance, reduced emissions, comfort, and acoustics are obtained.

For the 2003 model year DaimlerChrysler Corporation (DCC) will introduce an all-new 5.7L V8 truck engine manufactured at the new Saltillo II Engine Plant (SEPII) in Saltillo, Mexico. The product will debut in the new RAM series of pick-up trucks and marks the return of the hemispherical combustion chamber architecture. This paper covers the engine design features, simulation methods, development, and manufacturing processes. Also reviewed are the project objectives and the organizational processes used to manage and deliver the program.

The existence of the cyclic variation of the flow inside an cylinder affects the performance of the engine. Developing methods to understand and control in-cylinder flow has been a goal of engine designers for nearly 100 years. In this paper, passive control of the intake flow of a 3.5-liter DaimlerChrysler engine was examined using a unique optical diagnostic technique: Molecular Tagging Velocimetry (MTV), which has been developed at Michigan State University. Probability density functions (PDFs) of the normalized circulation are calculated from instantaneous planar velocity measurements to quantify gas motion within a cylinder. Emphasis of this work is examination of methods that quantify the cyclic variability of the flow. In addition, the turbulent kinetic energy (TKE) of the flow on the tumble and swirl plane is calculated and compared to the PDF circulation results.

Control System testing determines whether the embedded controller (software and its HWIO / hardware system) are operating according to specification. General Motors Powertrain (GMPT) has increased its span of test coverage through the use of automated testing. Further use of this type of testing is advised to enhance quality in a field that is rapidly growing more complex.

With the ever increasing popularity of SUV automobiles, studies involving driveline specific problems have grown. One prevalent NVH problem is axle whine associated with the assembled motion transmission error (MTE) of an axle system and the corresponding vibration/acoustic transfer paths into the vehicle. This phenomenon can result in objectionable noise levels in the passenger compartment, ensuing in customer complaints. This work explores the methodology and test methods used to diagnose and solve a field axle whine problem, including the use of cab mount motion transmissibility path analysis, running modes and a detailed MTE best-of-the-best (BOB)/worst-of-the-worst (WOW) study. The in-vehicle axle whine baseline measurements including both vehicle dynamometer and on-road test conditions, along with the countermeasures of axle whine fixes are identified and presented in this paper.