Efficient Automation of Homologation Tests for Active Aerodynamic Components

<div class="htmlview paragraph">This paper presents the basic test data obtained from tests of a cabin air distribution system in a simulated Space Station U.S. Lab-A module.</div> <div class="htmlview paragraph">The cabin air distribution system controls the flow of air in the open space of a Space Station module. In order to meet crew comfort criteria the local velocities for this cabin air are required to be distributed within a specified range with upper and lower limits. Achieving this desired velocity distribution is dependent upon the: (1.) design of the cabin air supply equipment and cabin air return equipment, (2.) total flowrate of air supplied to and subsequently returned from the cabin, and (3.) interactive effects of any other additional air flow streams which enter and exit the cabin.</div> <div class="htmlview paragraph">The basic Space Station design for the cabin air supply and air return equipment was used in this test program. Only directional adjustments to vanes in supply air diffusers were made during the test. This equipment is included in the Temperature and Humidity Control (THC) subsystem for the Space Station. Two other air streams, in addition to what is defined as THC cabin airflow, which were involved in the test program were:</div> <div class="htmlview paragraph"> <ol class="list nostyle"> <li class="list-item"> <span class="li-label">1.</span> <div class="htmlview paragraph">Standoff airflow – Standoffs are described in the paper. Briefly, they are enclosures within the cabin which formerly included ventilation fans. The consequent standoff airflow interacted with THC cabin airflow. The present baseline THC subsystem does not include the standoff fans.</div></li> <li class="list-item"> <span class="li-label">2.</span> <div class="htmlview paragraph">Intermodule Ventilation (IMV) Airflow – IMV assemblies are used to interchange airflow between Space Station modules. These modules include the U.S. Lab-A module, the nodes, and, later in the Space Station program, the international modules.</div></li></ol></div> <div class="htmlview paragraph">Test results from eight (8) of the test runs which demonstrate the ability for the air distribution system to meet its objectives are presented. These test run results are compared with each other with respect to their standing relative to meeting the test objectives.</div> <div class="htmlview paragraph">The test program investigated the effects of the variables noted above in meeting the test objectives. The basic variable in these test runs was the THC airflow. This airflow varied from 300 cfm to 500 cfm in the 8 test runs presented here. Some changes were made in supply air diffuser vane directional settings. Standoff airflow was used in one test run (number 4) and IMV airflow was used in test runs 5, 6, 7, and 8. Based on the test results, the desired velocity range and an engineering evaluation of the test results, a THC airflow rate for U.S. Lab-A is recommended.</div>

<div class="section abstract"> <div class="htmlview paragraph">This Recommended Practice provides a procedure for measuring and documenting the aerodynamic performance in a full-scale wind tunnel of passenger vehicles, i.e., mass-produced cars and light-duty trucks intended primarily for individual consumers. Testing or numerical modeling of pre-production and/or reduced-scale models is outside the scope of this document. Aerodynamic <i>development</i> procedures, i.e., methods to improve or optimize aerodynamic performance, are also excluded.</div> <div class="htmlview paragraph">It is well-known that aerodynamic performance results depend significantly on vehicle content and loading, as well as the wind tunnel itself (type, scale, and simulation qualities of the wind tunnel). Publication of non-standard test results causes unnecessary additional development work and incorrect perception of a vehicle’s anticipated aerodynamic performance by government, academia, and the general public.</div> <div class="htmlview paragraph">The intent of this document is to promote uniformity and traceability of published aerodynamic performance data acquired in a wind tunnel, thereby enhancing the public reputation and credibility of the aerodynamics discipline in the total vehicle development process.</div> <div class="htmlview paragraph">Measurement of the aerodynamic performance according to this Recommended Practice requires a full-scale wind tunnel test on a production-ready, full-scale vehicle according to specifications for vehicle loading, content, and wind tunnel conditions.</div> <div class="htmlview paragraph">The measurement and resulting documentation for a particular vehicle shall be reported only by the company that intends to produce the vehicle. Whenever there is an opportunity for interpretation of the document, a good faith effort shall be made to obtain the vehicle’s typical in-service performance and avoid finding the best possible performance under the best possible circumstances.</div> <div class="htmlview paragraph">Use of and compliance with this Recommended Practice is voluntary; however, it is mandatory for those advertising or otherwise publishing aerodynamic performance as “measured according to SAE J2881.” Conversely, any advertised or otherwise published result carrying this or a substantially similar designation must have the necessary documentation accepted by and on file with the SAE in accordance with the procedures defined in this Recommended Practice.</div> <div class="htmlview paragraph"><span class="xref">Appendices B</span> and <span class="xref">C</span> contain the necessary submittal documents for compliance with this Recommended Practice. When a submittal is made, the chairman of the Road Vehicle Aerodynamics Forum Committee (RVAC) or his/her designee shall review the submittal for proper completion according to the requirements herein, but without consideration of the technical merit of the claimed performance. After the chairman’s review, SAE will maintain an electronic database of all submittals.</div> <div class="htmlview paragraph">The database shall be available only to members and liasion members of the RVAC. Any RVAC member who retrieves information from the database shall do so with the understanding that the information is to be considered confidential within his or her company.</div></div>

<div class="htmlview paragraph">The Columbus laboratory module, developed by Astrium Bremen as prime contractor and Alenia Spazio as co-prime, is the European contribution to the International Space Station (ISS) program and as such it will support, once in orbit, micro-gravity and space based research activities of the member states.</div> <div class="htmlview paragraph">Columbus Environmental Control System (ECS) employs an Environmental Control and Life Support System (ECLSS) providing atmosphere pressure, cabin ventilation and temperature humidity control inside the module in conjunction with an autonomous Active Thermal Control System (ATCS) that provides the heat collection capability. The ATCS, based on software controlled water loop, provides also the cooling capability for Payloads and Subsystem equipment. The ECS is completed with the Passive Thermal Control System based on software controlled shell heating system plus passive fixtures such as Multi-Layers Insulation (MLI) blankets.</div> <div class="htmlview paragraph">Generally, both, the Columbus ATCS as well as the ECLSS are qualified via simplified but representative tests and concluding analyses. Complete verification of the module thermal and environmental control design however, will be performed via analysis supported by ECS System Level Integrated Test as well as the predictions for flight.</div> <div class="htmlview paragraph">With respect to responsibility sharing, Alenia is responsible for all verification by test related to thermal/environmental aspects, i.e. Alenia will define the test requirements and cases to be performed via the establishment of a dedicated test specification. On the other side, definition and production of the test set-up as well as the performance of the test is assigned to the Columbus prime Astrium SI Bremen.</div> <div class="htmlview paragraph">In order to get confidence on the functional performance of the Columbus ECS and to validate the Integrated Overall Thermal Mathematical Model (IOTMM) on system level the module will be subjected to an Integrated System Test (IST).</div> <div class="htmlview paragraph">Purpose of the ECS IST is to provide the first verification of the thermal/environmental interrelation between the active cooling (ATCS) and environmental control system (ECLSS) hardware and software and to collect as much characteristic thermal data as possible for the validation of the flight configuration IOTMM. This test will represent the second and last test in series on the flight configuration of the Columbus module.</div> <div class="htmlview paragraph">Previous tests, for verification of the functional interfaces of the ATCS and ECLSS, have been performed already in the frame of the Electrical Test Model (ETM) utilization. However, this test did not provide information on environmental and thermal parameters of the system but rather on the functional interrelations of the relevant units of the subsystems. Presently, the subject test will be performed in the integration hall of Astrium SI Bremen (Class 100.000 clean room conditions) and the pressurized shell is planned to be covered by the flight multi-layer insulation only located beneath the meteoroid debris panels (MDPS) of the module. However, in order to get as much as possible characteristic data of the system not only the test cases have to be selected very carefully but also additional test supporting equipment (TSE) has to be evaluated.</div> <div class="htmlview paragraph">The present paper summarizes the efforts generated to establish the Environmental/Thermal test in the frame of the system level IST of the Columbus module, describes the interrelation aspects of the thermal/environmental subsystem verification by test and analysis and presents the derived methodologies and expected results.</div>

<div class="htmlview paragraph">This paper describes the development process for acceleration sensors used on automobiles and acceleration evaluation system especially for the acceleration in super low range frequency.</div> <div class="htmlview paragraph">Acceleration sensor is indispensable not only for good vehicle motion control system, for example, active suspension control system, antiskid control system and four wheel steering control system, but also for safety system like air bag control system. This work focused on the development process of acceleration sensor which applied piezo ceramics.</div> <div class="htmlview paragraph">Features of newly developed sensor are as follows.</div> <div class="htmlview paragraph"> <ol class="list nostyle"> <li class="list-item"> <span class="li-label">1)</span> <div class="htmlview paragraph">Achievement of self-diagnostic function to detect sensor failure utilizing the characteristics of piezo ceramics</div> </li> <li class="list-item"> <span class="li-label">2)</span> <div class="htmlview paragraph">Addition of piezo ceramic to cancel the pyro-effect achieved stabilization of sensor characteristics and enabled to detect acceleration of 0.0025G in super low range frequency of 0.05Hz.</div> </li> <li class="list-item"> <span class="li-label">3)</span> <div class="htmlview paragraph">Incorporates impedance conversion, filtering and temperature characteristics compensation circuitry.</div> </li> </ol> </div> <div class="htmlview paragraph">Frequency range of acceleration for good vehicle motion control is considered to be from DC to about 50Hz.</div> <div class="htmlview paragraph">But the measurement of acceleration in thus super low range frequency near DC had been difficult because of its mechanical and electrical noise interruption.</div> <div class="htmlview paragraph">This had delayed the development of acceleration sensor for automotive use.</div> <div class="htmlview paragraph">We succeeded in the development of acceleration measurement system for super low range frequency from 0.01Hz to 2Hz with detecting acceleration range from 0.0002 (0.2 gal) G to 1G as well as the development of piezo type acceleration sensor for automotive use.</div>

<div class="section abstract"><div class="htmlview paragraph">Automatic transmission (AT) is a complex hydroelectromechanical system, since it consists of hydraulic, electrical and mechanical parts.</div><div class="htmlview paragraph">On cars produced by “UzAuto Motors” mainly AT of the 6T family, 6-speed AT family GM: 6T30, 6T40, 6T45, 6T50 “Hydra-Matic” are used.</div><div class="htmlview paragraph">Production of parts of these transmissions is carried out both at American GM plants and at GM plants in China and Korea.</div><div class="htmlview paragraph">The differences between AT 6T30/6T40/6T45/6T50 are in the thickness of the output chain and in the planetary gear, in the sizes of some other units and the housing itself. But the differences are much more influenced by the settings of the transmission unit, which select operating modes with different engines so as not to overload the thinnest places of the automatic transmission.</div><div class="htmlview paragraph">Automatic transmissions 6T30, 6T40, 6T45, 6T50 have the ability to manually shift gears and activate the “kickdown” mode (for quick acceleration of the car, when you sharply press the gas “all the way” it makes the automatic transmission downshift, and sometimes by two steps).</div><div class="htmlview paragraph">The operation of the transmission is controlled by various electronic systems that are responsible for the operability and structural integrity of the gearbox.</div><div class="htmlview paragraph">Failure of the automatic transmission can occur as a result of one or a combination of malfunctions of the following parts: in the torque converter; in the mechanical part of the gearbox; in the hydraulic part of the control system; one or more clutches of the gearbox; in the electrical part of the control system; in the electronic control unit.</div><div class="htmlview paragraph">The authors of the work investigated and determined the occurrence of malfunctions and failures depending on the temperature of the working fluid of the automatic transmission of a passenger car.</div><div class="htmlview paragraph">Also, the dependence of the resource of the automatic transmission on the temperature of the hydraulic fluid was obtained. High-quality diagnostics of the automatic transmission and its control system can in many cases save the car owner from expensive repairs: <ul class="list disc"><li class="list-item"><div class="htmlview paragraph">without thorough diagnostics, the automatic transmission cannot be subjected to routine or major repairs. Only on the basis of diagnostic information can a conclusion be made about the technical maintenance or repair of the automatic transmission;</div></li><li class="list-item"><div class="htmlview paragraph">based on real experience of operating passenger cars equipped with automatic transmission, we recommend changing the oil every 35000 miles under operating conditions in Tashkent. We also recommend conducting diagnostics of the automatic transmission every 12500 miles of the car's mileage.</div></li></ul></div></div>

<div class="section abstract"><div class="htmlview paragraph">Virtual simulation is a fundamental tool for the development of new vehicles, both for individual components and for complete subsystems and full vehicles. Many software tools exist in the automotive sector to assess full-vehicle behavior and performance, including multibody software and algorithms based on 14 (or more) degrees-of-freedom vehicle dynamics models. In order to reproduce the testing maneuvers and typical vehicle mission, a key part of such simulation tools is the virtual driver algorithm. It is essential to implement a control logic that reproduces the handling response of the driver, so that the closed-loop maneuvers can be evaluated. However, the response of typical virtual drivers is not always similar to the human driving characteristics. Virtual driver algorithms can perform very fast, precise, and smooth steering and pedal actions, while humans display a more variable, delayed and often not optimal actions.</div><div class="htmlview paragraph">The aim of this article is to describe the concept and implementation of a novel human-like path planning model. The algorithm is developed in MATLAB environment, creating a function that obtains a human-like path and vision logic by setting some key-parameters. They are: Distance Factor, Widening Factor, Cutting Factor, Inner Smoothing Factor and Outer Smoothing Factor.</div><div class="htmlview paragraph">The parameters - essential to alter the shape of the trajectory described in a track - have their values attributed by fitting experimental data gathered during test sessions in a driving simulator. The vehicle model used to implement the path planning system is based on the VI-Grade CarRealTime environment, in co-simulation with MATLAB/Simulink, and the results indicate that the novel algorithm has a closer correlation with the DiL tests than the original virtual driver. The stronger correlation is confirmed also in the comparison between different human drivers, showing that the proposed strategy is robust to driving styles.</div><div class="htmlview paragraph">Among the potential applications of this new “human-like virtual driver” approach is the ability to better predict human driver response during tuning and optimization of vehicles and control systems, apart from a further understanding of human driving behavior useful for tasks like ADAS and autonomous driving.</div></div>

<div class="htmlview paragraph">In order to suppress the well-documented low frequency pressure fluctuations in open jet wind tunnels, termed ‘wind tunnel buffeting’, an Active Resonance Control (ARC) System was implemented in the Audi aero-acoustic wind tunnel several years ago. This ARC-Sys-tem reduces the periodic pressure fluctuations by up to 23 dB and completely eliminates the periodic velocity fluctuations using a simple feedback control scheme.</div> <div class="htmlview paragraph">To set up the ARC system in practice, the system's parameters are optimised once for each critical flow velocity, when the vortex shedding frequency coincides with an acoustic resonance mode of the wind tunnel.</div> <div class="htmlview paragraph">Due to the fact that both frequency and amplitude of the excited resonances not only depend on flow velocity but also on other parameters such as collector position and test-car geometry, the system has to be adjusted with regard to each of these cases. Furthermore, experimental data suggests that multiple resonances are excited simultaneously under certain conditions.</div> <div class="htmlview paragraph">For these reasons a new, self-adapting control scheme was developed which combines the utilisation of the same physical mechanism of damping with greater control flexibility.</div> <div class="htmlview paragraph">The first part of this paper deals with experimentally measured pressure fluctuations and the influence different variables have on this phenomenon. The configuration of the self-adapting Enhanced Active Resonance Control (EARC) together with experimental results is presented in the second part of the paper.</div>

<div class="htmlview paragraph">In the past decade, SCR deNOx technology with urea injection has grown to maturity. European OEMs will apply SCR deNOx to meet future heavy-duty emissions legislation starting with EURO-4 (2005/2006). Numerous research programs in Europe and the US have shown a variety of system layouts and control strategies. The main differences are formed by:</div> <div class="htmlview paragraph"> <ul class="list disc"> <li class="list-item"><div class="htmlview paragraph">the engine-out NO<sub>x</sub> calibration</div> </li> <li class="list-item"><div class="htmlview paragraph">the application of an NO to NO<sub>2</sub> catalyst</div> </li> <li class="list-item"><div class="htmlview paragraph">open-loop or closed-loop urea dosage control.</div> </li> </ul> </div> <div class="htmlview paragraph">This paper gives an overview of possible SCR system configurations that are required for different stages of future emission legislation.</div> <div class="htmlview paragraph">Engine-out NO<sub>x</sub> emission is strongly influenced by ambient conditions. Projections in this study show that a combination of cold climate and a wintergrade fuel is the most severe: it may lead to 30% lower engine-out NO<sub>x</sub> emission with respect to laboratory conditions. The varying engine-out NO<sub>x</sub> emission requires a safety margin in the case of an open-loop controlled system in order to avoid excessive NH<sub>3</sub> slip.</div> <div class="htmlview paragraph">Calculations in this paper show that Euro 4 limits can be met with open-loop controlled urea dosage; an NO to NO<sub>2</sub> catalyst is even not required. For other future emission legislation (Euro 5, US 2007 and US 2010), it becomes difficult to safely achieve the limits with open-loop control. US 2007 and 2010 legislation require an NO to NO<sub>2</sub> catalyst because of the low average load and consequently low exhaust gas temperatures. Engines that are developed to meet US 2010 legislation need special measures to increase the exhaust gas temperature and to reduce engine-out NO<sub>x</sub> below 2 g/kWh.</div> <div class="htmlview paragraph">In all cases, optimal hydrolysis and mixing conditions are of major importance. High speed photography and droplet size measurements are presented as methods for characterizing and modeling aqueous urea spray patterns. The information from these measurements is used as input parameters for simulation tools. These consist of a 2D/3D CFD program for urea mixing analysis and a 1D SCR system model for development of dosage control and optimization of catalyst dimension.</div> <div class="htmlview paragraph">Finally, simulations with the SCR system model are compared with measurements on the engine test bench.</div>

<div class="htmlview paragraph">A continuously growing demand comes from the automotive industry for optimization of materials and sound insulating product packaging inside the car, so as to propose the best acoustic performance at reduced costs.</div> <div class="htmlview paragraph">A new acoustical holography system provides part of the solution to meet such a demand. The capability of measuring the acoustic field inside a vehicle with high spatial resolution makes it an advanced tool for performing extensive studies of the acoustic transparency of car openings and interior components in various environmental conditions (acoustic chamber, on road, in wind tunnel). The method allows for:</div> <div class="htmlview paragraph"> <ul class="list disc"> <li class="list-item"><div class="htmlview paragraph">Detailed localization of noise sources or leaks,</div></li> <li class="list-item"><div class="htmlview paragraph">Knowledge of the acoustic energy distribution on elementary surfaces (such as doors, windscreen, roof, sealing components, …),</div></li> <li class="list-item"><div class="htmlview paragraph">Reconstruction of the energy radiated by elementary surfaces in order to predict the acoustic pressure at driver's and passengers' ears,</div></li> <li class="list-item"><div class="htmlview paragraph">Introduction of local modifications on subsystems and components in order to predict their effect on the acoustic field.</div></li> </ul> </div> <div class="htmlview paragraph">In conjunction with some numerical prediction methods, this technique will allow to apply integrated acoustic engineering design methods for a complete understanding and control of the large variety of components and systems involved in the car performance.</div>

<div class="section abstract"> <div class="htmlview paragraph">Nondestructive tests are those tests which detect factors related to the serviceability or quality of a part or material without limiting its usefulness. Material defects such as surface cracks, laps, pits, internal inclusions, bursts, shrink, seam, hot tears, and composition analysis can be detected. Sometimes their dimensions and exact location can be determined. Such tests can usually be made rapidly. Processing results such as hardness, case depth, wall thickness, ductility, decarburization, cracks, apparent tensile strength, grain size, and lack of weld penetration or fusion may be detectable and measurable. Service results such as corrosion and fatigue cracking may be detected and measured by nondestructive test methods. In many cases, imperfections can be automatically detected so that parts or materials can be classified.</div> <div class="htmlview paragraph">The SAE Handbook describes the following nondestructive test methods:</div> <ol class="list nostyle"> <li class="list-item"> <div class="htmlview paragraph">SAE J359—Infrared</div></li> <li class="list-item"> <div class="htmlview paragraph">SAE J420—Magnetic Particle</div></li> <li class="list-item"> <div class="htmlview paragraph">SAE J425—Eddy Current</div></li> <li class="list-item"> <div class="htmlview paragraph">SAE J426—Liquid Penetrant</div></li> <li class="list-item"> <div class="htmlview paragraph">SAE J427—Penetrating Radiation</div></li> <li class="list-item"> <div class="htmlview paragraph">SAE J428—Ultrasonic</div></li> <li class="list-item"> <div class="htmlview paragraph">SAE J1242—Acoustic Emission</div></li> <li class="list-item"> <div class="htmlview paragraph">SAE J1267—Leakage Testing</div></li></ol> <div class="htmlview paragraph"><span class="xref">Table 1</span> summarizes the principal features of most of these tests. In addition to the tests described, other nondestructive tests exist which are less well established, but whose use is expanding. Among these are microwave tests, holography, and sonic tests. Microwaves are used to locate defects in nonmetallic substances and to determine some physical characteristics of those materials. Optical holography uses coherent light from a laser beam to detect strains and defects in materials by means of three-dimensional imaging and interferometry techniques. Acoustical holography uses ultrasonic waves to image discontinuities in the interior of solids. Recent refinements in sonic testing permit more objective determination of the physical properties of cast iron. Complete information concerning each nondestructive test can be obtained from books listed in the bibliographies of the aforementioned reports.</div> <div class="htmlview paragraph">Increasing consumer demand for product quality at reasonable cost has resulted in development of nondestructive tests which can be applied to materials and manufactured parts. Although a variety of complementary nondestructive methods is available, development time is generally required for application to specific materials or products. The effect of part contour, surface condition, heat treatment, composition variation, and other variables may limit the ability of certain tests to detect imperfections with desired accuracy.</div> <div class="htmlview paragraph">Nondestructive tests properly applied to basic material can add greater assurance of performance to design strengths, thereby affecting material and manufacturing economy. In addition, parts can be tested after each basic operation which is critical to service performance of the finished part. In-process nondestructive tests can also serve as basic components of feedback process control systems since all tests are based upon measurements which do not damage the material or part being inspected.</div></div>

<div class="htmlview paragraph">The use of graphical dynamic system simulation software is becoming more popular as automotive engineers strive to reduce the time to develop new control systems. The use of model-based control methods designed to meet future emission and diagnostic regulations has also increased the need for validated engine models. A previously validated, nonlinear, mean-torque predictive engine model<span class="xref">*</span> is converted to MATLAB / SIMULINK<span class="xref"><sup>†</sup></span> to illustrate the benefits of a graphical simulation environment. The model simulates a port-fuel-injected, spark-ignition engine and includes air, fuel and EGR dynamics in the intake manifold as well as the process delays inherent in a four-stroke cycle engine. The engine model can he used in five ways:</div> <div class="htmlview paragraph"> <ul class="list disc"> <li class="list-item"><div class="htmlview paragraph">As a nonreal-time engine model for testing engine control algorithms</div> </li> <li class="list-item"><div class="htmlview paragraph">As a real-time engine model for hardware-in-the-loop testing</div> </li> <li class="list-item"><div class="htmlview paragraph">As an embedded model within a control algorithm or observer</div> </li> <li class="list-item"><div class="htmlview paragraph">As a system model for evaluating engine sensor and actuator models</div> </li> <li class="list-item"><div class="htmlview paragraph">As a subsystem in a powertrain or vehicle dynamics model</div> </li> </ul> </div> <div class="htmlview paragraph">Although developed and validated for a specific engine, the model is generic enough to be used for a wide range of spark-ignition engines. Modular programming techniques reduce model complexity by dividing the engine and control system into hierarchical subsystems.</div>

<div class="htmlview paragraph">Wind tunnel interference effects are still considered to be negligible - or at least undesired - in automotive aerodynamics. Consequently, up to now there is no standard correction method which is used in everyday wind tunnel testing although a lot of research has been done in recent years.</div> <div class="htmlview paragraph">In most full-vehicle CFD simulations, wind tunnel interference effects are not simulated. The flow about the car is computed under idealized conditions. The wind tunnel is designed to simulate these conditions but fails to do so to some degree due to its limited size.</div> <div class="htmlview paragraph">Therefore a comparison of blockage-free CFD results and wind tunnel measurements is deficient. Hence CFD simulations including wind tunnel interference effects should be favored in the future for validation purposes. Furthermore, CFD offers new possibilities to investigate individual contributions to wind tunnel interference effects and therefore could help to increase the understanding of the flow in the wind tunnel. This may result in the development of advanced correction methods. To be able to use these possibilities, it has to be ensured that all effects of the whole wind tunnel test section with a car present will be captured in a simulation.</div> <div class="htmlview paragraph">In this paper simulations of the IVK model scale wind tunnel including wind tunnel interference effects are presented. As a first parameter variation, the influence of different longitudinal pressure distributions in the virtual test section are investigated and compared with test data. This investigation is presented here. In a second step, different vehicle models will be tested. All simulations were carried out with EXA PowerFLOW™.</div>

<div class="htmlview paragraph">In recent years, the fraction of air conditioning systems installed in American automobiles has increased to approximately 85%. Concurrently, efforts to improve fuel economy have resulted in smaller engines. The point has been reached in which load from a cycling fixed-displacement compressor can significantly affect vehicle drivability and performance. To remedy this problem, variable-capacity A/C systems have been developed with mechanically controlled compressor displacements.</div> <div class="htmlview paragraph">An alternative electronic approach to cooling capacity modulation is presented in this paper. The system utilizes a variable-speed brushless dc motor to drive a fixed-displacement compressor, thus achieving continuous control of cooling output independent of the engine drive belt. Compared to variable-displacement compressors, electrically driven A/C systems provide the following additional benefits: <ul class="list disc"> <li class="list-item"><div class="htmlview paragraph">Hermetic motor/compressor assembly (no shaft seal leakage)</div></li> <li class="list-item"><div class="htmlview paragraph">Smaller, less complex compressor</div></li> <li class="list-item"><div class="htmlview paragraph">Flexible packaging (no drive belt)</div></li> <li class="list-item"><div class="htmlview paragraph">Full cooling capacity at any engine speed</div></li> <li class="list-item"><div class="htmlview paragraph">Control of conditioned air temperature without reheat</div></li> </ul></div> <div class="htmlview paragraph">This paper deals with the development of a brushless dc drive system suitable for powering an automotive air conditioner. Two 5 hp motors were designed and built with maximum operating speeds of 6000 and 7000 rpm. These motors were then tested in a typical automotive air conditioning system over a range of operating conditions in order to determine their performance envelopes. The results are discussed, and conclusions are drawn as to the type of compressor and control strategy best suited for electric automotive A/C. Issues that are critical to the further development of electrically driven A/C systems are identified. An example simulation of annualized A/C system performance is also provided to quantify some of the benefits of cooling capacity modulation.</div>

<div class="section abstract"> <div class="htmlview paragraph">The SAE J3211 procedure applies to squeal evaluation for foundation brakes using single-ended inertia dynamometers for friction couples used on vehicles with regenerative braking systems. This document applies to squeal noise occurrences for on-road passenger cars and light trucks with a gross vehicle weight rating of 4536 kg or below and with at least one rechargeable energy storage system as a source for propulsion. The procedure incorporates aspects related to (a) minimum inertia dynamometer capabilities, (b) fixture requirements and setup, and (c) test sequences with emphasis on brake temperatures, brake pressure profiles, and strategies to represent brake blending.</div> <div class="htmlview paragraph">For this document, squeal occurs when the peak noise level is at least 70 dB(A) between 1.25 and 16 kHz for tests using full suspension corners or complete axle assemblies, or between 2 and 16 kHz for brakes not using an entire suspension corner.</div> <div class="htmlview paragraph">Test facilities intending to use this document, building on their expertise in conducting SAE J2521, shall review in detail the changes to test parameters (mainly brake temperatures and brake pressures) for legacy modules.</div> <div class="htmlview paragraph">This document also applies to vehicles with electromechanical braking systems to actuate the foundation brake. The test requester and the test facility are responsible for converting the hydraulic pressure levels into their equivalent clamping forces for brakes using electromechanical actuation.</div> <div class="htmlview paragraph">Before using this document for chassis dynamometer testing, review in detail the specifics related to at least (a) instrumentation, including in-cabin microphones; (b) threshold levels for noise detection; (c) temperature control priority between the front and rear axles; (d) vehicle loading and load distribution; (e) cooling air and environmental conditioning; (f) detailed terminology and labeling of channels and sensors; and (g) the regenerative settings and the state of charge during the test.</div> <div class="htmlview paragraph">Before using this document along with other methods to recreate the regenerative brake blending (e.g., Software-in-the-Loop or Hardware-in-the-Loop), consider (a) the vehicle powertrain, blending architecture and its applicable models, (b) actual profiles intended to recreate (e.g., control strategies, state of charge, test scenarios), and (c) actual embodiment of the simulation and integration with the native controls of the brake dynamometer.</div> <div class="htmlview paragraph">This document does not include noise from other sources (e.g., parking brakes, electric machines, driveline components).</div> </div>

<div class="section abstract"><div class="htmlview paragraph">Electric vehicle thermal management system is essential for electric vehicles to guarantee cabin thermal comfort and battery appropriate operating temperature. As a matter of fact, in such systems, high- and low-temperature driving conditions can severely affect system performance, in terms of overall efficiency and driving range. In this context, an effective thermal management solution both for cabin thermal comfort and battery heating/cooling is investigated in this paper.</div><div class="htmlview paragraph">A key innovation is the deep integration of the HVAC and battery heating/cooling circuits. Primarily, in winter scenario, the heat generated by the powertrain during operation is used to warm the cabin, thereby mitigating the necessity for additional electric cabin heating. This way, despite the inclusion of an extra heat exchanger, a consistent amount of heat can be recovered and the use of the battery energy for electrical heating activation is significantly reduced, as already presented by the authors in a previous study. Furthermore, the HVAC sub-system is designed so as to streamline hot or fresh air to the battery for heating or cooling purposes, respectively, resulting in a comprehensive and integrated solution that enhances overall energy efficiency, with minimum penalizations in cabin comfort.</div><div class="htmlview paragraph">This evaluation employs a 1-D model of the HVAC and battery heating/cooling integrated circuit and a 0-D model to interface it with the vehicle powertrain. A second order electrical equivalent circuit model is employed for the battery, to better capture transient behavior and heat generation, with all the parameters in the model being temperature-and SoC-dependent. Different control strategies are proposed for the management of the thermal system and various driving conditions, including scenarios during summer and winter with different speed profiles, are taken into account to assess their performance.</div><div class="htmlview paragraph">It is important to note that while this integrated approach introduces a degree of complexity, the benefits in terms of energy efficiency are shown to be substantial if the system control logic is designed properly. This multi-faceted analysis contributes valuable insights to the ongoing discourse on optimizing electric powertrains for enhanced performance and efficiency under diverse operating conditions.</div><div class="htmlview paragraph">The analysis carried out allows to effectively determine the influence of the HVAC sub-system on the battery state of charge, and then in terms of driving range, i.e. for the Helsinki driving cycle, the deactivation of the cabin heating allows the increase of about the 30% the driving time. It has been also highlighted how the different control strategy can influence the average battery temperature and as a consequence its internal resistance especially during winter scenario. Due to the high thermal load required during the summer driving conditions, the control strategy seems to be less effective.</div></div>