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Technical Paper

Characteristics of High-Pressure Spray and Exhaust Emissions in a Single- Cylinder Di Diesel Engine

2000-06-12
2000-05-0333
Regulations on exhaust emissions from light- and heavy-duty diesel engines have generated interest in high-pressure fuel injection systems. It has been recognized that high-pressure injection systems produce fuel sprays that may be more conductive to reducing exhaust emissions in direct-injection diesel engines. However, for such a system to be effective it must be matched carefully with the engine design and its operating parameters. A common-rail type of fuel injection system was investigated in the present study. The injection system utilizes an intensifier to generate injection pressures as high as 160 MPa. The fuel spray characteristics were evaluated on a test bench in a chamber containing pressurized nitrogen gas. The injection system was then incorporated in a single-cylinder diesel engine. The injection system parameters were adjusted to match engine specifications and its operating parameters.
Technical Paper

Transmission Mount Assembly Modelling for Load Simulation and Analysis

2007-04-16
2007-01-1348
Transmission mounts are usually tested as an assembly and typically only translational stiffnesses are provided. The torsional stiffness of the assembly is traditionally estimated based on experience in load simulation and analysis. This paper presents a procedure to estimate the torsional stiffness of the transmission mount assembly by using the test data. The effects of the torsional stiffness on the simulation results are also discussed.
Technical Paper

A Comparison of the Effect of E85 vs. Gasoline on Exhaust System Surface Temperatures

2007-04-16
2007-01-1392
With concerns over increasing worldwide demand for gasoline and greenhouse gases, many automotive companies are increasing their product lineup of vehicles to include flex-fuel vehicles that are capable of operating on fuel blends ranging from 100% gasoline up to a blend of 15% gasoline/85% ethanol (E85). For the purpose of this paper, data was obtained that will enable an evaluation relating to the effect the use of E85 fuel has on exhaust system surface temperatures compared to that of regular unleaded gasoline while the vehicle undergoes a typical drive cycle. Three vehicles from three different automotive manufacturers were tested. The surface of the exhaust systems was instrumented with thermocouples at specific locations to monitor temperatures from the manifold to the catalytic converter outlet. The exhaust system surface temperatures were recorded during an operation cycle that included steady vehicle speed operation; cold start and idle and wide open throttle conditions.
Technical Paper

Modeling, Validation and Dynamic Analysis of Diesel Pushrod Overhead Bridged Valve Train

2007-04-16
2007-01-1256
A bridged valve train configuration exhibits complex dynamic behavior due to the uniqueness of the special elephant foot/bridge/valve structure. Consequently, this system arrangement presents significant design challenges in system stability at high speed, high load, wear, no-follow and valve seating velocity, etc. An efficient way to gain a thorough understanding of the behavior of this type of valve train system and to drive the valve train design improvement is through the use of an effective dynamic simulation tool. In this paper, an advanced CAE tool developed by Ford Motor Company for the bridged type valve train simulations has been described. This automated CAE tool provides a complete virtual ADAMS-based simulation environment for the pushrod bridged valve train system analysis. This paper also presents the correlation and validation between the simulations and the measurements. The design analysis for the bridged valve train has been discussed briefly in this paper.
Technical Paper

Design of Vehicle Air Conditioning Systems Using Heat Load Analysis

2007-04-16
2007-01-1196
The objective of this paper is to describe a Computer Aided Engineering (CAE) model and its applications for A/C system development at early design stages. This CAE tool calculates the heat load of the vehicle passenger compartment with considerations of solar radiation, conductive/convective heat transfer through the body shell, and any passengers present in the vehicle. A data bank of 6 glass types, 9 surface finishes and 15 material properties are available to increase simulation flexibility. This heat load model can be used as a stand alone tool to calculate the steady-state thermal load of the passenger compartment under users' pre-defined conditions. When interfaced with an A/C refrigerant subsystem model, this integrated CAE tool is capable of evaluating the impacts on A/C system performance when body structures and/or operating conditions are changed.
Technical Paper

Failure Loads of Spot Friction Welds in Aluminum 6111-T4 Sheets under Quasi-Static and Dynamic Loading Conditions

2007-04-16
2007-01-0983
In this investigation, spot friction welds in aluminum 6111-T4 lap-shear specimens were tested under both quasi-static and dynamic loading conditions. Micrographs of the spot friction welds after testing were examined to understand the failure modes of spot friction welds in lap-shear specimens under different loading conditions. The micrographs indicate that the spot friction welds produced by this particular set of welding parameters failed in interfacial failure mode under both quasi-static and dynamic loading conditions. The load and displacement histories for lap-shear specimens were obtained under quasi-static and dynamic loading conditions at three different impact velocities. The failure loads of spot friction welds in lap-shear specimens under dynamic loading conditions are about 7% larger than those under quasi-static loading conditions.
Technical Paper

A CAE Methodology to Simulate Testing a Rearward Facing Infant Seat during FMVSS 208 Low Risk Deployment

2007-04-16
2007-01-1770
The Federal Motor Vehicle Safety Standard or FMVSS 208 requires passenger cars, multi-purpose vehicles, trucks with less than unloaded vehicle weight of 2,495 kg either to have an automatic suppression feature or to pass the injury criteria specified under low risk deployment test requirement for a 1 year old dummy in rearward and forward facing restraints as well as a forward facing 3 and 6 year old dummy. A convertible child seat was installed in a sub-system test buck representing a passenger car environment with a one-year- old dummy in it at the passenger side seat and a passenger side airbag was deployed toward the convertible child seat. A MADYMO model was built to represent the test scenario and the model was correlated and validated to the results from the experiment.
Technical Paper

Characterization of Exhaust Emissions in a SI Engine using E85 and Cooled EGR

2009-06-15
2009-01-1952
Gasoline-ethanol blends are being used or have been considered as a fuel for spark ignition engines. The motivation for using the blends varies in indifferent parts of the world and even in regions within a country. The increasing cost of gasoline, combined with regional tax incentives, is one of the reasons for increased interests in gasoline-ethanol blends in recent years in the U.S. Many vehicular engines are not designed to use a specific gasoline-ethanol blend. Rather, the engines have multi-blend capability, ranging from E0 to about E85. It is plausible that engine-out emissions will vary depending on the blend being used which may be further impacted by the level of EGR used with the blends. The present work was carried out to investigate engine out emissions when a vehicular spark-ignition engine was operated on E0 and E85 and different levels of EGR. A 4-cylinder, 2.5 liter, PFI engine was used in the experimental investigation.
Technical Paper

Optimizing R&H and NVH Performances Early in the Design Process via Multi Body Simulation

2009-05-19
2009-01-2087
This paper presents a CAE based approach to accurately simulate and optimize Ride and Handling metrics. Because of the wide range of vehicle phenomena involved, across the variety of frequency ranges, it is essential that the vehicle model includes proper representation of the dynamic properties of the various subsystems (e.g. tires, steering, PT, etc.) Precise correlation between test and simulation for standalone vehicle components and systems is achieved by replicating in the MBS (Multi-body Simulation) the same tests and boundary conditions. This allows the analyst to correctly define those crucial elements and parameters which have the greatest effect on the R&H attribute to be investigated. Setting up the simulation to correctly represent only one single maneuver simulation at a time would not allow the analyst to consider how the dynamic properties of the chassis design variables should be tuned to achieve to best balance and trade-offs.
Technical Paper

A Test-Based Procedure for the Identification of Rack and Pinion Steering System Parameters for Use In CAE Ride-Comfort Simulations

2009-05-19
2009-01-2090
Current CAE modeling and simulation techniques in the time domain allow, by now, very accurate prediction of many ride-comfort performances of the cars. Nevertheless, the prediction of the steering wheel rotation vibration excited by, for instance, wheel unbalance or asymmetric obstacle impact, often runs into the difficulty of modeling the steering line with sufficient accuracy. For a classic rack and pinion, hydraulic assisted steering line, one of the challenges is to model the complex and non linear properties - stiffness, friction and damping - of the rack-rack case system. This paper proposes a rack model, thought for easy implementation in complex multi-body models, and an identification procedure of its parameters, based on measurements, in the operational range of the wheel unbalance excitation. The measurements have been gathered by specific tests on the components and the test set-up is also shown here.
Technical Paper

Steering Grunt Noise Robustness Improvement

2009-05-19
2009-01-2095
Grunt is a structure-born noise caused by resonance of the steering gear torsion bar (T-bar) in an HPAS (Hydraulic Power Assist Steering) system. The goal of this work was to develop techniques to quantify and predict grunt in a RV (rotary valve) steering gear system. First, vehicle testing was used to identify an objective metric for grunt: y = dynamic pressure in the return line. Then, a computer simulation was developed to predict y as a function of two known control factors. The simulation results were correlated to measurements on a test vehicle. Finally, the simulation was expanded to include two additional control factors, and grunt predictions were demonstrated on a different test vehicle.
Technical Paper

Control of Powertrain Noise Using a Frequency Domain Filtered-x LMS Algorithm

2009-05-19
2009-01-2145
An enhanced, frequency domain filtered-x least mean square (LMS) algorithm is proposed as the basis for an active control system for treating powertrain noise. There are primarily three advantages of this approach: (i) saving of computing time especially for long controller’s filter length; (ii) more accurate estimation of the gradient due to the sample averaging of the whole data block; and (iii) capacity for rapid convergence when the adaptation parameter is correctly adjusted for each frequency bin. Unlike traditional active noise control techniques for suppressing response, the proposed frequency domain FXLMS algorithm is targeted at tuning vehicle interior response in order to achieve a desirable sound quality. The proposed control algorithm is studied numerically by applying the analysis to treat vehicle interior noise represented by either measured or predicted cavity acoustic transfer functions.
Technical Paper

Experimental Estimation of On-Vehicle Wheel-End Force and Application to Tire Flat-Spotting Effect

2009-05-19
2009-01-2160
Nibble is torsional vibration at the steering wheel of a vehicle. Typically it occurs at a resonant frequency of the steering and suspension system excited by the 1st harmonic tire/wheel force. A nibble target is established to be consistent with customer satisfaction target and then cascaded down to the targets for vehicle nibble sensitivity and tire/wheel inputs. Hence accuracy of the sensitivity and the tire/wheel force is important for a Computer Aided Engineering (CAE) nibble simulation. On-vehicle wheel-end forces are fore/aft and vertical tire/wheel forces acting on a vehicle spindle in an operating condition. This paper presents a methodology to estimate the wheel-end forces. The methodology was applied to investigate the effect of the tire flat-spot on the wheel-end forces. Tires were flat-spotted for one week and two months to simulate customer usage profiles. They were tested to measure the growth of the wheel-end forces.
Technical Paper

Sound Simulation and NVH Tuning of a Multi-Mode Engine

2009-05-19
2009-01-2191
This paper describes the use of an interactive NVH simulator in simulating and designing the sound character of a vehicle with a multi-mode engine and active exhaust valve. When designing a vehicle for sound quality, it is not sufficient to merely record some discreet operating conditions and modify these in a traditional sound quality program. The ability to simulate the sound quality of the vehicle over the full operating envelope is a necessity. Additionally, the ability to break down the sound contributions from intake, exhaust and other key contributors to the driver's ear, and manipulate these independently is also essential. In the case described here, an additional factor makes it mandatory that an accurate vehicle sound simulation is performed. The state of the engine and exhaust contribution, and thus the sound of the vehicle, change based on several parameters - vehicle speed, load demand and gear.
Technical Paper

Diagnostics for Diesel Particulate Filters

2004-03-08
2004-01-1422
This paper presents some of the challenges involved in diagnosing leaks in diesel particulate filters (DPFs). It concentrates on diagnosis with a pressure sensor. It is argued that not all failure modes can be detected by such a sensor, and that this method of diagnosis has far-reaching implications on the monitor completion frequency. Via an error analysis of commercially available sensors we argue that there is little to no separation between healthy and damaged particulate filters. The challenges are illustrated with straightforward analytical calculations.
Technical Paper

Effects of MMT® Fuel Additive on Emission System Components: Comparison of Clear- and MMT®-fueled Escort Vehicles from the Alliance Study

2004-03-08
2004-01-1084
Emission studies were carried out on clear-fueled and MMT®-fueled 100,000-mile Escort vehicles from the Alliance study [SAE 2002-01-2894]. Alliance testing had revealed substantially higher emissions from the MMT-fueled vehicle, and the present study involved swapping the engine cylinder heads, spark plugs, oxygen sensors, and catalysts between the two vehicles to identify the specific components responsible for the emissions increase. Within 90% confidence limits, all of the emissions differences between the MMT- and Clear-vehicles could be accounted for by the selected components. NMHC emission increases were primarily attributed to the effects of the MMT cylinder head and spark plugs on both engine-out and tailpipe emissions. CO emission increases were largely traced to the MMT cylinder head and its effect on tailpipe emissions. NOx emission increases were linked to the MMT catalyst.
Technical Paper

An Excel Based Robust Design Tool for Vehicle Structural Optimization

2004-03-08
2004-01-1124
To reduce the cost of prototype and physical test, CAE analysis has been widely used to evaluate the vehicle performance during product development process. Combining CAE analysis and optimization approach, vehicle design process can be implemented more efficiently with affordable cost. Reliability based design optimization (RBDO) formulation considers variations of input variables, such as component gauges and material properties. As a result, the design obtained by using RBDO is more reliable and robust compared to those by deterministic optimization. The RBDO process starts from running simulation at DOE sampling data points, generating surrogate models (response surface) and performing robust and reliability based design optimization on the surrogate models by using Monte Carlo simulation. This paper presents a RBDO framework in Excel enviroment.
Technical Paper

Reliability-Based Design Optimization of a Vehicle Exhaust System

2004-03-08
2004-01-1128
This paper focuses on the methodology development and application of reliability-based design optimization to a vehicle exhaust system under noise, vibration and harshness constraints with uncertainties. Reliability-based design optimization provides a systematic way for considering uncertainties in product development process. As traditional reliability analysis itself is a design optimization problem that requires many function evaluations, it often requires tremendous computational resources and efficient optimization methodologies. Multiple functional response constraints and large number of design variables add further complexity to the problem. This paper investigates an integrated approach by taking advantages of variable screening, design of experiments, response surface model, and reliability-based design optimization for problems with functional responses. A typical vehicle exhaust system is used as an example to demonstrate the methodology.
Technical Paper

Comparison of Dual Retard VCT to Continuously Variable Event Valvetrain

2004-03-08
2004-01-1268
Variable cam timing strategies which utilize retard of the intake and exhaust valve events at part load have been previously shown to provide improved fuel consumption and feedgas NOx. These benefits can be increased by enhancing the combustion system with variable charge motion. A variable event duration valvetrain was simulated on engine dynamometer by running a series of short duration/low lift intake valve events. The fuel consumption benefit for this simulated variable event valvetrain is compared to that of dual retard VCT with variable charge motion. An estimated upper limit for the fuel consumption improvement potential of variable valve timing is presented. This upper limit includes both pumping work reduction and indicated efficiency improvement with high levels of exhaust residual dilution. The measured benefits of dual retard VCT and of the variable event valvetrain are compared to the estimated upper limit.
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