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Insight: Fuel Effiency: Fuel Economy Testing (DVD)

"Spotlight on Design: Insight" features an in-depth look at the latest technology breakthroughs impacting mobility. Viewers are virtually taken to labs and research centers to learn how design engineers are enhancing product performance/reliability, reducing cost, improving quality, safety or environmental impact, and achieving regulatory compliance. As global concerns about the negative consequences of greenhouse gases on the environment increase, regulatory agencies around the world are taking serious steps to address the issue of tailpipe emissions In the episode "Fuel Efficiency: Fuel Economy Testing" (12:01), engineers at the EPA’s National Vehicle and Fuel Emissions Laboratory demonstrate how different vehicles are tested for emissions, and AVL’s technical team shows how accurate tailpipe emissions can be measured and reported.
Technical Paper

Developing Robust Vibration Excitation and Control Methods for Evaluating Rattle Noise in Automotive Components

The authors participated in a task force that was required to develop a repeatable, dependable, and reliable test procedure to compare, rate, and evaluate the severity of rattles. The assemblies involved in the study are designed and manufactured by different companies and are tested by different people on test equipment and instrumentation from different suppliers. The challenges therefore, were considerable and involved both the vibration inputs and responses as well as the acoustic responses. At the beginning of this activity, it was observed that different test labs using the same Ford vibration specs were obtaining different sounds from the same test item! Clearly, this was unacceptable and the test methods had to be improved and standardized. This paper focuses on vibration related to rattle testing. The particular assemblies used in this study were seat belt retractors.
Technical Paper

A Method to Measure Air Conditioning Refrigerant Contributions to Vehicle Evaporative Emissions (SHED Test)

Although the intent of the SHED test (Sealed Housing for Evaporative Determination) is to measure evaporative fuel losses, the SHED sampling methodology in fact measures hydrocarbons from all vehicle and test equipment sources. Leakage of air conditioning (AC) refrigerant is one possible non-fuel source contributing to the SHED hydrocarbon measurement. This report describes a quick and relatively simple method to identify the contribution of AC refrigerant to the SHED analyzer reading. R134A (CH2FCF3), the hydrofluorocarbon refrigerant used in all current automotive AC systems, as well as its predecessor, the chlorofluorocarbon R12, can be detected using the gas chromatography methods currently in place at many emissions labs for the speciation of exhaust and evaporative hydrocarbon emissions.
Technical Paper

Development of an Engine Head Friction Tester

An engine head friction tester that has excellent repeatability, can differentiate between oils with good and poor friction properties and can also obtain steady sequential data for many hours has been developed. It was formerly thought that data variations were inevitable in this type of tester. However, analysis of specific factors of the variations showed that the main factors involved in the variation were the temperature gradient between the head and the torquemeter and the temperature change resulting from the aforementioned temperature gradient. Next, by almost completely separating the head side from the torquemeter side thermally and by taking measures to maintain both sides at their respective constant temperatures, along with other countermeasures, a tester having the special properties indicated above was developed. This paper describes some test results demonstrating the advantages listed above.
Technical Paper

Using Modern Technology to Improve Truck Seating

Many advancements have been made through the use of technology that give seat manufacturers the capability to provide greatly improved truck seats. Until recently the design and development of new seating was accomplished primarily through static surveys. Modern technologies available today will reduce cost, development time, and the overall effort associated with utilizing real people to develop a seating project. In many instances when these seats were placed into vehicles with actual truck drivers riding in them for many hours a day, the drivers inputs resulted in multiple revisions to the original seat to satisfy their comfort issues. With modern technologies such as computer generated seat modeling, pressure mapping, and our state of the art test equipment such as a six–axis ride simulator, it has become part of any new seat development program to acquire field ride data in specific trucks and duplicate these inputs in the test laboratory.
Technical Paper

Vehicle Calibration on the TestBed (VCOT)

This paper presents engine performance and emission results that demonstrate a high degree of correlation between tests performed on a transient engine dynamometer with simulated vehicle characteristics, and test performed on a chassis rolls with a vehicle. The transient testing methodology that has been developed is being used to underpin the transfer of vehicle calibration activity to the testbed.
Technical Paper

Diesel Particulate Measurements with a Light Scattering Photometer

A light scattering photometer has been used to measure the diesel particulate emission from a vehicle to assess the capability of this instrument by comparing with the results from the traditional filter collection method and also with an opacimeter. Tests were conducted on a diesel vehicle mounted on a chassis dynamometer with its exhaust directed to a double dilution tunnel. Different types of test were carried out, including steady speed tests at different engine loads and transient tests. It was found that the correlation between the average particulate mass concentrations determined from the photometer and the filters changed with engine operating conditions. Comparison between the real-time outputs from the photometer and the opacimeter showed an excellent agreement in their particulate emission patterns measured during the transient tests. In conclusion, the photometer demonstrates a good potential in its application to diesel particulate measurements.
Technical Paper

The Audi Aeroacoustic Wind Tunnel: Final Design and First Operational Experience

Audi's new full scale aeroacoustic wind tunnel is under full operation now. The new facility is designed for full scale automotive testing of aerodynamics and aeroacoustics for vehicles up to 3 m2 frontal area at wind speeds up to 300 kph. The highlights are the unique ground simulation system with boundary layer suction and a 5-belt-system, and the extremely low background noise of only 60 dB(A) at 160 kph. First the background of the project is illustrated and the need for the special features of the tunnel is deduced form the industrial requirements. Then an overview of the facility design is given with a detailed description of the key technical components. The calibration of the self-correcting test section will be discussed and the physical background for it will be examined more closely. For the calibrated wind tunnel the results of two correlation tests including open jet as well as closed wall wind tunnels show a reasonable conformity.
Technical Paper

Approach to Realization of Micro-gravity Performance of Centrifuge Rotor System

The Centrifuge Rotor (CR) system, presented at the last ICES (Ohtomi et al., 1999) and scheduled to be launched in 2004, provides an artificial gravitational environment for biological specimens housed in habitats on the International Space Station (ISS). This paper presents the concept and investigation for realizing the micro-gravity (micro-g) performance, that is, the vibration suppression performance of the CR system which is the artificial gravity generator. The CR is a significant new development that will provide artificial gravity for gravitational experiments involving relatively large biological specimens such as small animals and plants. The CR rotates habitats located radially around the axis and generates centrifugal force, imposing artificial gravity of arbitrary magnitude up to 22.0 m/s2 (about 2.2 g) on the specimens housed in the habitats.
Technical Paper

The Application of Direct Body Excitation Toward Developing a Full Vehicle Objective Squeak and Rattle Metric

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.
Technical Paper

Equipment for Accelerated Reliability Testing of Cars and their Components

This paper analyses the current approaches in the development of accelerated stress testing, and describes why present test equipment cannot provide the simulation of simultaneous combination of basic field influences on the car and car's components. The authors show a new perspective for the evalution of equipment development for accelerated testing (AT) which would eliminate the above negative aspect and solve the problem of accurate simulation of real life input influences on the natural product for its reliability improvement.
Technical Paper

Testing Elastomers - Can Correlation Be Achieved Between Machines, Load Cells, Fixtures and Operators?

At present, testing elastomeric parts is performed at a level dictated by the users of the testing equipment. No society or testing group has defined a formal standard of testing or a way to calibrate a testing machine. This is in part due to the difficulty involved with testing a material whose properties are in a constant state of flux. To further complicate this issue, testing equipment, testing procedures, fixtures, and a host of other variables including the operators themselves, all can have an impact on the characterization of elastomers. The work presented in this paper looks at identifying some of the variables of testing between machines, load cells, fixtures and operators. It also shows that correlation can be achieved and should be performed between companies to ensure data integrity.
Technical Paper

Towards a Standard for Material Friction Pair Testing to Reduce Automotive Squeaks

Today vehicle owners perceive squeaks and itches inside a vehicle cabin as a major negative indicator of vehicle build quality and durability. Manufacturers struggle to bear the high costs of squeak and rattle (S&R) related warranty. Although the benefits of structural integrity and tight manufacturing tolerances with respect to the prevention of S&R are known, today's cost, weight, crash requirements, aesthetic demands and environmental/fire hazard rules quite often dictate the design of S&R prone sub-systems. Even sub-systems with the best possible structural design and manufacturing tolerances are not immune to extreme environmental conditions, and mating materials can initiate contact leading to S&R. One method of minimizing the possibility of squeaks is by the judicious selection of mating material pairs. This paper describes a test process aimed at the quantification of material pair compatibility.
Technical Paper

A Quantitative Analysis of the Effects of Rolls Coupling on Fuel Economy and Emission Levels

The effect of coupling chassis dynamometer rolls (front to rear) on city and highway fuel economy and emissions was investigated. A representative fleet of ten Ford certification vehicles (five passenger cars and five trucks) was tested in coupled and uncoupled roll configurations. Testing was conducted on a Clayton CTE-50 dynamometer with a hydrokinetic power absorption unit (P.A.U.) which was calibrated at a single point (50 mph). It was found that emission levels increased significantly (95% confidence level) for all constituents except city-NOx, which demonstrated mixed results. Observed fuel economy was reduced for both city and highway (3.6% and 4.0%, respectively, for a combined Metro/Highway (M/H) reduction of 3.8%) when the rolls were coupled.
Technical Paper

Road Load Measurement and Dynamometer Simulation Using Coastdown Techniques

Reduction of vehicle road load is important in the overall effort to improve fuel economy in motor vehicles. The ability to accurately simulate vehicle road load on a chassis dynamometer is similarly critical in the process of measuring fuel economy on such a dynamometer. This paper discusses coastdown techniques of road load measurement and dynamometer simulation from the standpoint of SAE Recommended Practice J1263 developed by an SAE Task Force between 1976 and 1979. These techniques are compared to other methods and the equations used to determine the absorber setting which duplicates vehicle road load for a single parameter chassis dynamometer are developed.
Technical Paper

Automatic Datalogging Techniques for Automotive Applications

New instrumentation designs require extensive proveout in the vehicle environment. The sheer magnitude of information required to evaluate today’s microprocessor-based systems precludes manual data collection and analysis. A method of automating the data collection process through direct communication with the instrumentation module is discussed. A design for an automatic data collector, or datalogger, is presented.
Technical Paper

Dynamometer Simulation of Truck and Bus Road Horsepower for Transient Emissions Evaluations

Appropriate chassis dynamometer simulation of road power for truck tractor-trailers and buses were required for emissions evaluations. To establish such simulations, the power required to operate vehicles over a roadway (speed-power relationship) was determined for two truck tractor-trailers and one city bus. Results of these determinations, along with data reported in the literature, were used to determine the power to be absorbed by a chassis dynamometer to simulate On-road driving of trucks and buses. The chassis dynamometer is being used in the subsequent phases of this study involving emissions evaluations of heavy duty vehicles. THE PURPOSE OF THIS PAPER is to describe the findings associated with road power determination and simulation for heavy-duty trucks and buses. Included is a general discussion of road power, along with the results of evaluations on the road and on the chassis dynamometer.
Technical Paper

Analysis of Road Load Losses in Cars on Standard Driving Cycles and Road Tests

In order to have a better understanding of fuel consumption of vehicles in real operating conditions, the Fiat Research Center is carrying out an extensive research on an instrumented Ritmo car. The first results of this research show that the estimate of road load is quite easy by using simple laws and experimental indoor measures. But the distribution of energy losses experienced during a series of road tests reproducing actual italian use patterns can only partially be reproduced by mixes of standardized road and/or chassis dynamometer standardized tests.
Technical Paper

A Proposal for an Engine Dynamometer Procedure for Evaluating the Relative Fuel Efficiency of Engine Oils

A multi-vehicle chassis dynamometer procedure for evaluating an engine oil for fuel economy effects has been accepted by ASTM and the lubrication industry with reservation. The reservation stems from the high test cost, the poor repeatability/reproducibility, and a concern that some additive chemistries are not being fairly evaluated. Recognizing these concerns, ASTM Committee D-2 has agreed to continue development work, but the thrust will now be toward a Sequence type, dynamometer engine test. The work which will be described here is part of a statistically designed study intended to screen operating conditions and hardware for their effects on fuel efficiency and test reliability. Three ASTM FEEO oils were evaluated relative to the FEEO reference oil HR-2 in a 2.8 L V-6 engine. Correlation with results from the 5-car test development program will be presented, as well as the results of the analysis for operating condition effects and sources of test variability.