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Technical Paper

Wall Heat Flux on Impinging Diesel Spray Flame: Effect of Hole Size and Rail Pressure under Similar Injection Rate Condition

2020-10-30
2020-32-2313
The fuel economy of recent small size DI diesel engines has become more and more efficient. However, heat loss is still one of the major factors contributing to a substantial amount of energy loss in engines. In order to a full understanding of the heat loss mechanism from combustion gas to cylinder wall, the effect of hole size and rail pressure under similar injection rate conditions on transient heat flux to the wall were investigated. Using a constant volume vessel with a fixed impingement wall, the study measured the surface heat flux of the wall at the locations of spray flame impingement using three thin-film thermocouple heat-flux sensors. The results showed that the characteristic of local heat flux and soot distribution was almost similar by controlling similar injection rate except for the small nozzle hole size with increasing injection pressure.
Technical Paper

Investigations on NOx and Smoke Emissions Reduction Potential through Diesel-Water Emulsion and Water Fumigation in a Small Bore Diesel Engine

2020-10-30
2020-32-2312
In the present work, a relative comparison of addition of water to diesel through emulsion and fumigation methods is explored for reducing oxides of nitrogen (NOx) and smoke emissions in a production small bore diesel engine. The water to diesel ratio was kept the same in both the methods at a lower concentration of 3% by mass to avoid any adverse effects on the engine system components. The experiments were conducted at a rated engine speed of 1500 rpm under varying load conditions. A stable water-diesel emulsion was prepared using a combination of equal proportions (1:1 by volume) of Span 80 and Tween 80. The mixture of Span 80 in diesel and Tween 80 in water was homogenized using an IKA Ultra Turrax homogenizer with tip stator diameter 18mm at 5000 rpm for 2 minutes. The water-in-diesel emulsions thus formulated were kinetically stable and appeared translucent. No phase separation was observed on storage for approximately 105 days.
Technical Paper

Transitioning from IC Engine to Electric Vehicle: An Optimized Wheel End Solution

2020-10-05
2020-01-1632
This paper discusses the change in vehicle parameters when moving from a conventional internal combustion engine to electric motor. It discusses the impact on the wheel end bearings. Typically these include higher GAWRs (Gross Axle Weight Rating) at lower center of gravity heights. These changes require bearings to handle higher loads. Typically, larger loads will increase the bearing size and with it the mounting interface dimensions to auxiliary components. Timken demonstrates an alternative bearing design that can handle higher vehicle GAWRs but would allow for continuity in the surrounding brake corner components – saving OEMs significant design costs and delays.
Technical Paper

A Full-System Approach to Maximise Energy Efficiency of a Wheel Bearing

2020-10-05
2020-01-1631
Environmental sustainability is morphing Automotive technical development strategies and driving the evolution of vehicles with a speed and a strength hardly foreseeable a decade ago. The entire vehicle architecture is impacted, and energy efficiency becomes one of the most important parameters to reach goals, which are now not only market demands, but also based on regulatory standards with penalty consequences. Therefore, rolling drag from all bearings in multiple rotating parts of the vehicle needs to be reduced; wheel bearings are among the biggest in size regardless of the powertrain architecture (ICE, Hybrid, BEV) and have a significant impact. The design of wheel bearings is a complex balance between features influencing durability, robustness, vehicle dynamics, and, of course, energy efficiency.
Technical Paper

Enclosure-In-Chamber Setup to Achieve Near-Zero Background Concentrations for Brake Emissions Testing

2020-10-05
2020-01-1634
Measuring brake emission is still a challenging non-standardized task. Extensive research is ongoing. Updates of work in progress are presented at SAE Brake Colloquium and PMP meetings. However, open items include how to achieve lower background concentration and how to design the brake enclosure. A low background concentration is essential as brake events are short and some emit in the range of reported background levels. Hence these emissions are difficult to distinguished from the background level. Even more critical, a high background concentration can result in a wrong particle number emissions value, either overestimated, background counted as emissions, or underestimated, background level subtracted, and low emission events no longer detected and counted. However, reducing the background level to less than 100 #/cm³ appeared to be quite challenging.
Technical Paper

Anodization: Recent Advancements on Corrosion Protection of Brake Calipers

2020-10-05
2020-01-1626
Brake calipers for high-end cars are typically realized using Aluminum alloys, with Silicon being the most common alloying element. Despite the excellent castability and machinability of AlSix alloys, anodization is often necessary in order to provide to AlSix components the required corrosion resistance or when the braking system has to withstand to severe chloride-rich environments [1]. Even if the anodization process is known for almost 100 years, a continuous research and process optimization can lead to the development of anodic layers with enhanced morphological and electrochemical properties, which enable a prolonged resistance of calipers under endurance corrosive tests (e.g. >1000hours Neutral Spray Tests).
Technical Paper

Topology Optimization of Brake Caliper

2020-10-05
2020-01-1620
The objective of the research is to develop a lightweight yet stiff, 2 piston fixed brake caliper which can be used in formula student race car. To make a race car, its components need to be lighter. To stop a car with minimum stopping distance, it needs to have a sophisticated braking system with well-designed components. The designing of the caliper is carried out on the Altair Inspire software. The topology optimization algorithm is used to minimize the weight of the caliper without compromising the stiffness. The structural analysis is also carried out on the Altair Inspire. The caliper is also tested for fatigue failure using Ansys.
Technical Paper

Coarse Mesh RIFF Method to Identify the Homogenized Flexural and Shear Complex Moduli of Composite Beams

2020-09-30
2020-01-1579
Facing the increasing use of composite materials regarding their stiffness to mass ratio, industries need to design complex structures. Hence specific methods must developed to predict the vibratory behavior of such materials but also to check their performances in-situ, analyse the presence of flaws or quantify degradation of properties throughout time. This paper describes a method to estimate the flexural and shear complex moduli of composite beams, based on a simple measurement of the transverse displacement on a coarse mesh using a hammer and an accelerometer. The herein depicted approach consists in an adaptation of the corrected finite difference scheme (Leclere et al. 2012) applied to an inverse vibratory method developed by the authors in previous works (Wassereau et al. 2017). The Timoshenko’s equation of motion and the corrected finite difference scheme are the two major key points of the method.
Technical Paper

Optimization Of Vehicle Damping Sheets Position Based On Energy Calculation

2020-09-30
2020-01-1528
As a common means for reducing vibration and noise for automobiles, damping material is usually employed in the vehicle body, typically on the floor, the dashboard, and the top roof. With the growing demand of fuel economy, light weighting, as well as NVH comfort, the optimization of the damping pads has become a topic of increasing importance. In numerical simulation, the traditional methods generally make use of the modal strain energy of the metal sheet as the main indicator for making layout choice for the damping pads. The optimization is not performed according the vehicle’s real working condition. Furthermore, the traditional methods do not depend on the accurate properties of the damping material. In this paper, a novel optimization method based on energy analysis is presented.
Technical Paper

Root Cause Analysis and Structural Optimization of E-Drive Transmission

2020-09-30
2020-01-1578
We face a growing demand for so-called eAxles (electric axle drive) in vehicle development. An eAxle is a compact electric drive solution for full electric vehicles (and P4 hybrids) with integrated electric machine and transmission. The transmission can be rather simple using fixed gear with cylindrical gear steps but increasing demands on power and speed range as well as efficiency increase its complexity with planetary stages or switchable gear steps. Such an electro-mechanic system has different behavior than the classical ICE-driven powertrains, for example regarding NVH, where high frequency and tonal noise from gear whining and electro-magnetic excitation is an important comfort issue that needs to be understood and controlled.
Technical Paper

Design of a Multiwaves Vibration Filtering

2020-09-30
2020-01-1560
In vibroacoustics, bandgap effects related to periodic and/or locally resonant architectural materials can lead to new types of structural vibration filters. This communication concerns periodic pipes used in industrial context. Such pipes are seen, as architectural structural waveguides in which bending, torsional, and longitudinal waves can propagate. To control the propagation of these vibrations and reduce their possible noise disturbance, Bragg or resonant band effects can be obtained by architecting the axial variations of the cross-section. As a result, a waveguide can be tuned to create stop bands with bandwidths large enough to make them interesting for industrial applications. For this purpose, dispersion relations are derived and analyzed based on the Floquet method and numerical Finite Element simulations. In many practical cases, all kinds of waves generally coexist due to the inevitable structural couplings.
Technical Paper

Study of the Glass Contribution to the Interior Acoustics of a Car and Related Countermeasures

2020-09-30
2020-01-1585
This paper shows that the collaboration between a glass manufacturer and a passive acoustic treatment manufacturer can bring different benefits and considerably improve the interior acoustics of a vehicle. In terms of passenger safety and well-being, glazing have always played a key role by offering solutions to interior comfort, particularly when it comes to heat and acoustics. Today, cars are becoming a living space which from an acoustic point of view brings a challenge for the interior comfort. Indeed, glazing has no absorption and classically it has an acoustic insulation weakness around its coincident frequency. In most of the cases, these different aspects make glazing one of the main contributors to the sound pressure level in the passenger compartment, and the trend is not one of change. However, there are possible countermeasures. One of which is the use of laminated glazing with acoustic PVB.
Technical Paper

NVH Optimization Methods Applied to e-Motors

2020-09-30
2020-01-1531
Noise-vibration-harshness (NVH) is now playing an important role in electric vehicle development process. Experience shows that the NVH criteria must be considered at the very early stages of the concept design phase. Finite Elements (FE) models are widely used to simulate the vehicle design. To achieve a correct accuracy of a FE model, the results of an experimental modal analysis (EMA) are commonly applied to a FE model via correlation and updating processes. Thus, different kinds of optimization might be used throughout the concept design duration. This paper describes, first, the use of a parametric optimization to tune a FE model in high frequencies relying on the results of the EMA test. Then the frequency response analysis is conducted to detect the critical frequencies for the NVH performance. Based on the results of this analysis, a topographic optimization is performed.
Technical Paper

Using Statistical Energy Analysis to Optimize Sound Package for Realistic Load Cases

2020-09-30
2020-01-1525
The statistical energy analysis (SEA) is widely used to support the development of the sound package of cars. This paper will present the preparation of a model designed to investigate the sound package of the new Audi A3 and associated correlation against measurements. Special care was given during the creation of the model on the representation of the structure to enable the analysis of structure borne energy flow on top of the classical airborne analysis usually done with SEA. The sound package was also detailed in the model to allow further optimization and analysis of its performance. Two real life load cases will be presented to validate the model with measurements. First, the dominating powertrain and a second load case with dominating rolling noise. An analysis of the contribution of the different source components and a way to diagnose the weak paths of the vehicle will be presented. The focus of this investigation is the application of optimally adjusted treatment.
Technical Paper

Robust Development of Electric Powertrain NVH for Compact Electric SUV

2020-09-30
2020-01-1503
Electric vehicles (EV's) present new challenges to achieving the required noise, vibration & harshness performance (NVH) compared with conventional vehicles. Specifically, high-frequency noise and abnormal noise, previously masked by the internal combustion engine can also cause annoyance in an EV. Electric motor (E-motor) whine noise caused by electromagnetic excitation during E-motor operation is caused by torque ripple and stator local excitation. Under high speed and high load operating conditions, the sound level is low, however high frequency whine noise is a factor that can impair the vehicle level NVH performance. An example of a previously masked abnormal noise is a droning noise that can be caused by manufacturing quality variation of the spline coupling between the rotor shaft of the E-motor and the input shaft of the reducer, it is dominated by multiple higher orders of the E-motor rotation frequency.
Technical Paper

A Generic Testbody for Low-Frequency Aeroacoustic Buffeting

2020-09-30
2020-01-1515
Raising demands towards lightweight design paired with a loss of originally predominant engine noise pose significant challenges for NVH engineers in the automotive industry. From an aeroacoustic point of view, low frequency buffeting ranks among the most frequently encountered issues. The phenomenon typically arises due to structural transmission of aerodynamic wall pressure fluctuations and/or, as indicated in this work, through rear vent excitation. A possible workflow to simulate structure-excited buffeting contains a strongly coupled vibro-acoustic model for structure and interior cavity excited by a spatial pressure distribution obtained from a CFD simulation. In the case of rear vent buffeting no validated workflow has been published yet. While approaches have been made to simulate the problem for a real-car geometry such attempts suffer from tremendous computation costs, meshing effort and lack of flexibility.
Technical Paper

Experimental Investigation on the Effects of Cooled Low Pressure EGR and Water Injection on Combustion of a Turbocharged GDI Engine

2020-09-27
2020-24-0003
This work focuses on the effects of cooled Low Pressure EGR and Water Injection observed by conducting experimental tests consisting mainly of Spark Advance sweeps at different cooled LP-EGR and WI rates. The implications on combustion and main engine performance indexes are then analysed and modelled with a control-oriented approach, showing that combustion duration and phase and exhaust gas temperature are the main affected parameters. Results show that cooled LP-EGR and WI have similar effects, being the associated combustion speed decrease the main cause of exhaust gas temperature reduction. Experimental data is used to identify control-oriented polynomial models able to capture the effects of LP-EGR and WI on both these aspects. The limitations of LP-EGR are also explored, identifying maximum compressor volumetric flow and combustion stability as the main ones.
Technical Paper

An Analytical Procedure to Analyse Efficiency, Cooling and Thermal Management of a BEV Sport Car Transmission

2020-09-27
2020-24-0023
The implementation of increasingly stricter regulations on CO2 emissions by the European Community is pushing the automotive industry towards a radical change. In a rush to electrify their model ranges, global carmakers are investing heavily on developing new electrified powertrains. Within this context, this work focuses on the analysis of electric axles drives (eAxles) for a BEV (battery electric vehicle) sport car, with the aim to develop an analytical tool useful to perform predictive analysis in the concept design phase. Through a parametric definition of the procedure, the tool with its 2800 lines of code is able to “adapt” to any drivetrain layout analysed. The tool actually allows to enter more than 100 input values including lubrication conditions (oil viscosity and operating temperature), gears (number, macrogeometry, mesh), bearings (number, type, geometry, mounting layout, angle mesh), shafts, oil seals, external layout and external fluid conditions.
Technical Paper

Determination of energy-saving potentials by reducing the rolling bearing friction in the tractor drive train

2020-09-27
2020-24-0024
Increased efficiency and emission reduction have, in recent years, introduced several changes in the architecture of agricultural tractors transmissions. As one of the leading rolling bearing manufacturers for this industry, Schaeffler has explored energy saving potentials related to rolling bearings friction reduction. Starting point of the activity is the actual status of the design of tractor transmission manufactured by one of the key players in the sector.
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