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Technical Paper

Experimental Investigation of Fuel Film Characteristics of Ethanol Impinging Spray at Ultra-Low Temperature

2017-03-28
2017-01-0851
Increasing the injection pressure in DISI engine is an efficient way to obtain finer droplets but it will also potentially cause spray impingement on the cylinder wall and piston. Consequently, the fuel film sticking on the wall can dramatically increase the soot emission of the engine especially in a cold start condition. On the other hand, ethanol is widely used as an alternative fuel in DI engine due to its sustainable nature and high octane number. In this study, the fuel film characteristics of single-plume ethanol impinging spray was investigated. The experiments were performed under ultra-low fuel/plate temperature to simulate the cold start condition in cold areas. A low temperature thermostatic bath combined with specially designed heat exchangers were used to achieve ultra-low temperature for both the impinging plate and the fuel. Laser induced fluorescence (LIF) technique was employed to measure the thickness of fuel film deposited on the impinging plate.
Technical Paper

Voltec Battery Design and Manufacturing

2011-04-12
2011-01-1360
In July 2007, GM announced that it would produce the Chevy Volt, the first high-production volume electric vehicle with extended range capability, by 2010. In January 2009, General Motors announced that the Chevrolet Volt's lithium ion Battery Pack, capable of propelling the Chevy Volt on battery-supplied electric power for up to 40 miles, would be designed and assembled in-house. The T-shaped battery, a subset of the Voltec propulsion system, comprises 288 cells, weighs 190 kg, and is capable of supplying over 16 kWh of energy. Many technical challenges presented themselves to the team, including the liquid thermal management of the battery, the fast battery pack development timeline, and validation of an unproven high-speed assembly process. This paper will first present a general overview of the approach General Motors utilized to bring the various engineering organizations together to design, develop, and manufacture the Volt battery.
Technical Paper

Road Map and Technology Trends for Vehicle Engine Cooling Fan Speed Control

2011-04-12
2011-01-1334
This paper describes the rationale for the technology selection and speed control methods for electric cooling fans used for typical automotive applications, including most passenger cars and even some light duty truck s. Previous selection criteria were based primarily around cost, simplicity of implementation and reliability. However, the more recent focus toward fuel economy and optimization of energy consumption at a vehicle level has given a greater priority to the minimization of electrical power draw. Specifically, that need is addressed through both efficiency of the electric motor at any operating condition as well as providing a control method that delivers only the minimum electrical power to meet engine cooling and air conditioning requirements. This paper will explore the various control methods available, their relative merits and shortcomings and how they influence both FTP and real world fuel economy.
Technical Paper

Lubricant Flow and Temperature Prediction in a Planetary Gearset

2011-04-12
2011-01-1235
This study introduces a method to examine the flow path of the lubricant inside a planetary gearset of an automatic transmission. A typical planetary gearbox has several load bearing elements which are in relative sliding motion to each other which causes heat to be released. The major sources of friction as well as heat are the meshing teeth between gears (sun/planet, planet/ring), thrust washers, thrust bearings and needle bearings. The lubricant performs the vital function of both lubricating these sliding interfaces and cooling these sources of heat, thereby preventing failure of the gearbox. The exact flow path that the lubricant takes inside a planetary gearset is unknown. Since the gearset is primarily splash lubricated, it is also not known how much lubricant reaches critical areas. A method is developed using computational fluid dynamic techniques to enable comprehensive flow and thermal analysis and visualization of an automatic transmission assembly.
Technical Paper

A Statistical Approach for Correlation/Validation of Hot-Soak Terminal Temperature of a Vehicle Cabin CFD Model

2013-04-08
2013-01-0854
A Design for Six Sigma (DFSS) statistical approach is presented in this report to correlate a CFD cabin model with test results. The target is the volume-averaged hot-soak terminal temperature. The objective is to develop an effective correlation process for a simplified CFD cabin model so it can be used in practical design process. It is, however, not the objective in this report to develop the most accurate CFD cabin model that would be too expensive computationally at present to be used in routine design analysis. A 3-D CFD model of a vehicle cabin is the central part of the computer modeling in the development of automotive HVAC systems. Hot-soak terminal temperature is a thermal phenomenon in the cabin of a parked vehicle under the Sun when the overall heat transfer reaches equilibrium. It is often part of the simulation of HVAC system operation.
Technical Paper

Visualization and Analysis of Condensation in Exhaust Gas Recirculation Coolers

2013-04-08
2013-01-0540
Cooled exhaust gas recirculation (EGR) is widely used in diesel engines to control engine-out NOx (oxides of nitrogen) emissions. A portion of the exhaust gases is re-circulated into the intake manifold of the engine after cooling it through a heat exchanger. EGR cooler heat exchangers, however, tend to lose efficiency and have increased pressure drop as deposit forms on the heat exchanger surface due to transport of soot particles and condensing species to the cooler walls. In this study, condensation of water vapor and hydrocarbons at the exit of the EGR cooler was visualized using a fiberscope coupled to a camera equipped with a complementary metal oxide semiconductor (CMOS) color sensor. A multi-cylinder diesel engine was used to produce a range of engine-out hydrocarbon concentrations. Both surface and bulk gas condensation were observed with the visualization setup over a range of EGR cooler coolant temperatures.
Technical Paper

Multi-Disciplinary Analyses for Brake Fluid Temperature Evaluation

2013-04-08
2013-01-0635
During braking events, a brake corner sustains high brake torque, generating a large amount of heat in the process. This is most significant during mountain descent events and vehicle race track events. The brake thermal events not only reduce brake friction coefficient and lining life, but also produce elevated brake fluid temperature. Traditionally, brake hardware testing is warranted to evaluate brake fluid temperature for high speed flat track and mountain descent. These tests are costly and time-consuming. A CAE process to predict brake fluid temperature early in the vehicle development process before hardware exists, and to reduce and to replace testing will greatly benefit the vehicle development process. To this end, multiple analyses can be run. The heat transfer coefficients and cooling coefficients were evaluated from relevant CFD analyses.
Technical Paper

Optimization of Scratch Resistance for Molded in Color Interior Thermoplastic Olefin Injection Molded Plastics

2011-04-12
2011-01-0464
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.
Technical Paper

Structural-Acoustic Analysis of Vehicle Body Panel Participation to Interior Acoustic Boom Noise

2011-04-12
2011-01-0496
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.
Technical Paper

Method and System for Determining the Location of a Lost Vehicle Key Fob

2011-04-12
2011-01-0044
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.
Technical Paper

Modeling of Battery Pack Thermal System for a Plug-In Hybrid Electric Vehicle

2011-04-12
2011-01-0666
Fuel economy and stringent emissions requirements have steered the automotive industry to invest in advanced propulsion hybrids, including Plug-in hybrid vehicles (PHEV) and Fuel cell vehicles. The choice of battery technology, its power and thermal management and the overall vehicle energy optimization during different conditions are crucial design considerations for PHEVs and battery electric vehicles (BEV). Current industry focus is on Li-Ion batteries due to their high energy density. However, extreme operating temperatures may impact battery life and performance. Different cooling strategies have been proposed for efficient thermal management of battery systems. This paper discusses the modeling and analysis strategy for a thermally managed Lithium Ion (Li-Ion) battery pack, with coolant as the conditioning medium.
Technical Paper

Vehicle Crash and Steering Column Frequency Simulation of an Aluminum Instrument Panel Structure

2011-04-12
2011-01-0765
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.
Technical Paper

Interpretation of SAE J1100 Cargo Volume Indices

2011-04-12
2011-01-0779
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.
Technical Paper

Measurement of Occupant Pocketing Kinematics During Whiplash Assessments

2011-04-12
2011-01-0270
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.
Technical Paper

A Multidisciplinary Numerical Modeling Tool Integrating CFD and Thermal System Simulation for Automotive HVAC System Design

2012-04-16
2012-01-0644
A multidisciplinary toolset integrating ANSYS FLUENT CFD solver and GM in-house thermal system design tool - e-Thermal has been developed to design automotive HVAC systems. This toolset utilizes COM software interface standard of MS Windows for inter-process communication at simulation run-time to synchronize the two applications and to exchange data. In this report, first, the implementation of this fully transient, coupled method between FLUENT CFD and e-Thermal is introduced. We then apply this integrated tool to simulate a transient A/C operating cycle including hot-soak and cool-down of a cabin. The coupled simulation consists of an A/C and an Air-Handling (HVAC module) system models, and a cabin CFD model. It demonstrates that the coupled method can simulate fully transient HVAC system operations in a vehicle.
Technical Paper

Test Method for Seat Wrinkling and Bagginess

2012-04-16
2012-01-0509
This study evaluates utilizing an accelerated test method that correlates customer interaction with a vehicle seat where bagginess and wrinkling is produced. The evaluation includes correlation from warranty returns as well as test vehicle results for test verification. Consumer metrics will be discussed within this paper with respect to potential application of this test method, including but not limited to JD Power ratings. The intent of the test method is to aid in establishing appropriate design parameters of the seat trim covers and to incorporate appropriate design measures such as tie downs and lamination. This test procedure was utilized in a Design for Six Sigma (DFSS) project as an aid in optimizing seat parameters influencing trim cover performance using a Design of Experiment approach.
Technical Paper

Optimal Use of Boosting Configurations and Valve Strategies for High Load HCCI - A Modeling Study

2012-04-16
2012-01-1101
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.
Technical Paper

Utilizing Finite Element Tools to Model Objective Seat Comfort Results

2012-04-16
2012-01-0074
The comfort assessment of seats in the automotive industry has historically been accomplished by subjective ratings. This approach is expensive and time consuming since it involves multiple prototype seats and numerous people in supporting processes. In order to create a more efficient and robust method, objective metrics must be developed and utilized to establish measurable boundaries for seat performance. Objective measurements already widely accepted, such as IFD (Indentation Force Deflection) or CFD (Compression Force Deflection) [1], have significant shortcomings in defining seat comfort. The most obvious deficiency of these component level tests is that they only deal with a seats' foam rather than the system response. Consequently, these tests fail to take into account significant factors that affect seat comfort such as trim, suspension, attachments and other components.
Technical Paper

Consumer Sensitivity to Vehicle Interior Component Adjustments

2012-04-16
2012-01-0075
The number of adjustable vehicle interior components features is growing. For example, the number of adjustable components of a vehicle seat has been growing from 4-way to as many as 22-way. The presented study aims to develop understanding on how sensitive drivers and front passengers are to individual component adjustment of vehicle interior features. This understanding could provide insights on which adjustable vehicle interior components features are more important to be precisely adjusted. A commercially available full-size sedan, equipped with a 4-way adjustable steering column & wheel and an 8-way adjustable seat for drivers, and an 8-way adjustable seat for front passengers, was used in this study. A total of 29 and 30 consumers were participating in this study to adjust components to their comfort on driver and front passenger sides, respectively.
Technical Paper

Determining Most Energy Efficient Cooling Control Strategy of a Rechargeable Energy Storage System

2011-04-12
2011-01-0893
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.
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