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Three different acoustic finite element models of an automobile passenger compartment are developed and experimentally assessed. The three different models are a traditional model, an improved model, and an optimized model. The traditional model represents the passenger and trunk compartment cavities and the coupling between them through the rear seat cavity. The improved model includes traditional acoustic models of the passenger and trunk compartments, as well as equivalent-acoustic finite element models of the front and rear seats, parcel shelf, door volumes, instrument panel, and trunk wheel well volume. An optimized version of the improved acoustic model is developed by modifying the equivalent-acoustic properties. Modal analysis tests of a vehicle were conducted using loudspeaker excitation to identify the compartment cavity modes and sound pressure response to 500 Hz to assess the accuracy of the acoustic models.

This research examined driver acceptance and behavior associated with Speed Limit and Curve Advisor systems, including influences on speed choice. Drivers experienced messages from an emulated Speed Limit and Curve Advisor system during a 2-hour public road drive. Driver tolerance for system errors and message conflicts was also studied by manipulating the accuracy of the information provided by the system. Messages were presented using either a Head-Up Display or on an in-dash Driver Information Center. Results indicate that drivers liked having speed limit information continuously available to them while driving, but the information provided by the Speed Limit Advisor did not significantly influence or alter drivers' speed choice or deceleration profiles in comparison to driving without the system.

Cast aluminum alloys are normally quenched after solution treatment or solidification process to improve aging responses. Rapid quenching can lead to high residual stress and severe distortion which significantly affects dimension stability, functionality and particularly performance of the product. To simulate residual stress and distortion induced during quenching, a finite element based approach was developed by coupling an iterative zone-based transient heat transfer algorithm with material thermo-viscoplastic constitutive model. With the integrated models, the numeric predictions of residual stresses and distortion in the quenched aluminum castings are in a good agreement with experimental measurements.

General Motors' (GM) eAssist powertrain builds upon the knowledge and experience gained from GM's first generation 36Volt Belt-Alternator-Starter (BAS) system introduced on the Saturn VUE Green Line in 2006. Extensive architectural trade studies were conducted to define the eAssist system. The resulting architecture delivers approximately three times the peak electric boost and regenerative braking capability of 36V BAS. Key elements include a water-cooled induction motor/generator (MG), an accessory drive with a coupled dual tensioner system, air cooled power electronics integrated with a 115V lithium-ion battery pack, a direct-injection 2.4 liter 4-cylinder gasoline engine, and a modified 6-speed automatic transmission. The torque-based control system of the eAssist powertrain was designed to be fully integrated with GM's corporate common electrical and controls architectures, enabling the potential for broad application across GM's global product portfolio.

Conventional HVAC systems adjust the position of a temperature door, to achieve a required air temperature discharged into the passenger compartment. Such systems are based upon the fact that a conventional (non-hybrid) vehicle's engine coolant temperature is controlled to a somewhat constant temperature, using an engine thermostat. Coolant flow rate through the cabin heater core varies as the engine speed changes. EREVs (Extended Range Electric Vehicles) & PHEVs (Plug-In Hybrid Electric Vehicles) have two key vehicle requirements: maximize EV (Electric Vehicle) range and maximize fuel economy when the engine is operating. In EV mode, there is no engine heat rejection and battery pack energy is consumed in order to provide heat to the passenger compartment, for windshield defrost/defog and occupant comfort. Energy consumption for cabin heating must be optimized, if one is to optimize vehicle EV range.

This paper describes the development of an improved method for Noise and Vibration (N&V) chassis dynamometer testing using Road Load Simulation (RLS). Powertrain-induced noise and vibration testing on a chassis dynamometer has commonly been conducted using fixed loads or simplistic load versus speed approximations. Simple speed control and load control dyno test conditions are largely sufficient to provide representative noise and vibration performance assessment when the powertrain and its controls are insensitive to differences between the actual road load and the dyno load. With the recent growth of advanced engine control systems and hybrid powertrains, more representative road load simulation is required to ensure proper operation of the increasingly sophisticated and diverse powertrain and chassis control systems. Proper exercise of these control systems often determines the quality of the noise and vibration data.

Spot, or distributed, cooling and heating is an energy efficient way of delivering comfort to an occupant in the car. This paper describes an approach to distributed cooling in the vehicle. A two passenger CFD model of an SUV cabin was developed to obtain the solar and convective thermal loads on the vehicle, characterize the interior thermal environment and accurately evaluate the fluid-thermal environment around the occupants. The present paper focuses on the design and CFD analysis of the energy efficient HVAC system with spot cooling. The CFD model was validated with wind tunnel data for its overall accuracy. A baseline system with conventional HVAC air was first analyzed at mid and high ambient conditions. The airflow and cooling delivered to the driver and the passenger was calculated. Subsequently, spot cooling was analyzed in conjunction with a much lower conventional HVAC airflow.

Key fobs, also known as remote keys or remote transmitters, have become a common piece of equipment in today's vehicle, being ubiquitous in every market segment. Once limited to remote locking and unlocking operations, today's key fobs can be used to control many comfort and security features beyond locking and unlocking, such as alarm system operation, vehicle locate, approach lighting, memory seat recall, and remote starting systems. Key fobs are designed to be easy to use as well as easy to carry and transport in personal containers, such as purses, pockets, wallets, and the like. Accordingly, as with other personal effects, key fobs and other portable remote devices can be lost or misplaced or can be otherwise difficult to find. Even with careful tracking of a remote device, children and pets, among other factors, can make location difficult. Moreover, multiple remote devices are often distributed with each vehicle.

The increasing usage of brake-by-wire systems in the automotive industry has provided manufacturers with the opportunity to improve both vehicle and manufacturing efficiency. The replacement of traditional mechanical and hydraulic control systems with electronic control devices presents different potential vehicle-level safety hazards than those presented by conventional braking systems. The proper design, development, and integration of a brake-by-wire control system requires that hazards are reasonably prevented or mitigated in order to maximize the safety of the vehicle operator, occupant(s), and passers-by.

This study documents a method developed for dynamically measuring occupant pocketing during various low-speed rear impact, or “whiplash” sled tests. This dynamic pocketing measurement can then be related to the various test parameters used to establish the performance rating or compliance results. Consumer metric and regulatory tests discussed within this paper as potential applications of this technique include, but are not limited to, the Insurance Institute for Highway Safety (IIHS) Low Speed Rear Impact (LSRI) rating, Federal Motor Vehicle Safety Standard (FMVSS) 202a, and European New Car Assessment Program (EURO-NCAP) whiplash rating. Example metrics are also described which may be used to assist in establishing the design position of the head restraint and optimize the balance between low-speed rear impact performance and customer comfort.

To realize better fuel economy benefits from transmissions, car makers have started the application of torque converter clutch control in second gear and beyond, resulting in greater demand on the torque converter clutch (TCC) and its control system. This paper focuses on one aspect of the control of the torque converter clutch to improve fuel economy and faster response of the transmission. A TCC is implemented to control the slip between the pump and turbine of the torque converter, thereby increasing its energy transfer efficiency and increasing vehicle fuel economy. However, due to the non-linear nature of the torque converter fluid coupling, the slip feedback control has to be very active to handle different driver inputs and road-load conditions, such as different desired slip levels, changes in engine input torques, etc. This non-linearity requires intense calibration efforts to precisely control the clutch slip in all the scenarios.

The engineering of electric propulsion systems requires time and cost efficient methodologies to determine system characteristics as well as potential component integration issues. A significant part of this analysis is the identification of the electromagnetic fields present in the propulsion system. Understanding of the electromagnetic fields during system operation is a significant design consideration due to the use of components that require large current(s) and high voltage(s) in the proximity of other control system items (such as sensors) that operate with low current(s) and voltage(s). Therefore, it is critical to quantify the electromagnetic fields produced by these components within the design and how they may interact with other system components. Often overlooked (and also extremely important) is an evaluation of how the overall system architecture can generate or react to electromagnetic fields (which may be a direct result of packaging approaches).

Recent changes to the U.S. CAFÉ (Corporate Average Fuel Economy) requirements have caused increased focus on alternative vehicle component designs that offer mass savings while maintaining overall vehicle design and performance targets. The instrument panel components comprise approximately 6% of the total vehicle interior mass and are thus a key component of interest in mass optimization efforts. Typically, instrument panel structures are constructed of low carbon tubular steel cross car members with welded stamped steel component brackets. In some cases, instrument panel structures have incorporated high strength low alloy (HSLA) steels to reduce mass by reducing gage. In this study, aluminum low mass instrument panel structure concept designs are developed. This paper illustrates the differences between a HSLA steel solution and four different aluminum instrument panel structure designs.

As customer dissatisfaction with interior trim components is tracked by the JDPowers question on “surface durability”, there is a need to increase the durability of the parts that are molded in color. In particular, door trim panel lowers are susceptible to surface damage which results in an unfavorable appearance. To address this issue, an assessment of the various factors that can affect surface durability was conducted using talc filled TPO materials in order to determine the optimum set of physical properties. The team used Design for Six Sigma (DFSS) methodology. A Taguchi orthogonal experiment was used and included control system factors of material, grain, gloss, and color. Noise factors included molding process parameters, aging, and piece to piece variation. The output was a measure of the scratch resistance of the molded plaque which was defined by a Delta L calculation.

A structural-acoustic finite element model of an automotive vehicle is developed and applied to evaluate the effect of structural and acoustic modifications to reduce low-frequency ‘boom’ noise in the passenger compartment. The structural-acoustic model is developed from a trimmed body structural model that is coupled with an acoustic model of the passenger compartment and trunk cavities. The interior noise response is computed for shaker excitation loads at the powertrain mount attachment locations on the body. The body panel and modal participation diagrams at the peak response frequencies are evaluated. A polar diagram identifies the dominant body panel contributions to the ‘boom’ noise. A modal participation diagram determines the body modes that contribute to the ‘boom’ noise. Finally, structural and acoustic modifications are evaluated to determine their effect on reducing the ‘boom’ noise and on the overall lower-frequency sound pressure level response.

This study investigates a novel approach towards boosted HCCI operation, which makes use of all engine system components in order to maximize overall efficiency. Four-cylinder boosted HCCI engines have been modeled employing valve strategies and turbomachines that enable high load operation with significant efficiency benefits. A commercially available engine simulation software, coupled to the University of Michigan HCCI combustion and heat transfer correlations, was used to model the HCCI engines with three different boosting configurations: turbocharging, variable geometry turbocharging and combined supercharging with turbocharging. The valve strategy features switching from low-lift Negative Valve Overlap (NVO) to high-lift Positive Valve Overlap (PVO) at medium loads. The new operating approach indicates that heating of the charge from external compression is more efficient than heating by residual gas retention strategies.

SAE J1100 - Motor Vehicle Dimensions was first published in September 1973. One of the many significant aspects of this recommended practice is that it provides procedures for estimating cargo/luggage volume in various types of vehicles. Passenger vehicles typically carry cargo in one of two areas: those that are separate from the passenger compartment and those that are open to the passenger compartment. A closed compartment is: An area intended to carry or stow luggage or cargo for personal or commercial purposes that is distinct or enclosed from the area used to transport people. The volume of this area is quantified by a physical stack of simulated luggage pieces, and include the following body types: coupes, sedans, and convertibles. An open compartment is: An area intended to carry or transport luggage or cargo for personal or commercial purposes that is open to the passenger compartment. These areas have the potential to carry people or cargo.

Plug in hybrid electric vehicles (PHEV) and electric vehicles (EV) are using large lithium ion battery packs to store energy for powering electric traction motors. These batteries, or Rechargeable Energy Storage Systems (RESS), have a narrow temperature operating range and require thermal management systems to properly condition the batteries for use in automotive applications. This paper will focus on energy optimization of a RESS cooling system. The battery thermal management system for the General Motors Chevrolet Volt has three distinct modes for battery cooling: active cooling, passive cooling, and bypass. Testing was conducted on each individual thermal cooling mode to optimize, through control models, the energy efficiency of the system with the goal of maximizing electric vehicle range.

As the automotive industry moves toward producing more advanced hybrid/electric vehicles, high voltage Rechargeable Energy Storage Systems (RESS) are now being implemented as the main power source of the vehicle, replacing the need for the traditional Internal Combustion Engine (ICE) altogether or just during certain parts of a drive cycle. With this type of architecture, it is becoming a necessity to equip these vehicles with devices that can draw their power from the high voltage (HV) RESS. These HV devices are not only used to support the propulsion of the vehicle but to perform other necessary vehicle functions as well. With demands of high voltage power from multiple systems ranging from RESS thermal conditioning, cabin thermal conditioning, RESS charging, and vehicle propulsion, power demands can exceed the available power of the vehicle. This creates a perplexing problem of how to manage the high voltage power consumption between the different vehicle systems.

The development and validation of an electric vehicle presents numerous issues that are not normally encountered during the development of a traditional internal combustion powered vehicle. Many of the issues that are encountered involve components that are common to both electric and internal combustion vehicles but are utilized in new or unique ways that may present challenges during the development process. The integration of the electric motors, power supply, batteries, and associated content into a traditional vehicle can bring new and challenging issues to light. This paper discusses the solution for an issue that arose during the testing and development of the chassis and powertrain hardware of an electric vehicle. In particular, the large rotational inertia of the electric drive motor presented significant challenges when it was accelerated by forces that were external to the drive unit.