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This paper describes idle vibration reduction methods using a Stellantis vehicle as a case study. The causes of idle vibration are investigated using the NVH source, path, and receiver method. The torque transfer path into a vehicle has shown to be very important in determining vehicle idle vibration response. New electronic control enablers that affect idle vibration are tested and discussed, including Neutral Idle Control (NIC), Transfer-case Idle Control (TIC,®), and Switchable Engine Mounts (SEM). The Design For Six Sigma (DFSS) analysis method is used to arrive at an optimized result for vehicle idle vibration. In addition, Stellantis has developed a new idle vibration control enabler known as Transfer-case Idle Control (TIC), which was awarded by the US patent Office and will be applied on future vehicles. This paper also discusses the results confirming TIC’s capability of reducing idle vibration on all-wheel drive vehicles.

The charge air cooler, which is placed between the compressor and the engine intake manifold, is an important component in a turbocharged engine. Air, already hot and under high pressure from the compressor, passes through many small fin tubes in the core of the charge air cooler which decreases the temperature of the air before it enters the engine cylinder. This process increases both engine power and efficiency. To improve the predictive accuracy of engine performance and intake noise using a 1-D GT-power model, it is essential for the charge air cooler model to capture all the parameters of the component, whether it is temperature change, pressure drop or the acoustical wave behavior. Although there may be flow-induced high frequency noise content present from the compressor, low frequency engine intake order noise is more dominant of the overall intake noise level for a turbocharged engine.

An Inline 4-cylinder engine is equipped with second-order balance shafts. When the engine is running under a low load acceleration condition, the gear system of the balance shaft generated whine noise. In this paper, an analysis method for reducing the whine noise is presented. First, a flexible multi-body dynamic model of the engine is established, which includes shaft and casing deformation, micro-modification of the balance shaft gears. Taking the measured cylinder pressure as the input, the influence of the micro-modification of the gears’ tooth surface at the balance shaft on the meshed noise was calculated and analyzed. The torsional vibration at the crankshaft nose was measured during no-load conditions, and the measured data was compared with the estimated data, which validate the established multi-flexible body dynamic model of the engine. Secondly, a quasi-static model of the balance shaft gear transmission was established.

Current trends of advanced automotive engines focus on downsizing, better fuel efficiency, and lower emissions, which lead to several advancements in turbocharger designs and technology. More recent trends in electric and hybrid powertrains have further brought additional sources into the NVH balance. With vehicle environments becoming quieter, this has posed a great challenge in controlling undesirable noise from boosting systems. Boosting systems provide oxygen through boosted air pressure, to ICE or fuel cell systems, to improve their efficiency and limit their CO2 and pollutant emissions. Boosting systems are also key elements in current and new electrical and hybrid powertrains. During real driving conditions, the rotational speed of boosting systems (turbomachines and compressors) varies greatly, which makes them produce different noise signatures that can be unpleasant for the end users.

HVAC systems are of critical importance in ensuring passengers’ thermal comfort inside the car cabin as well as safety requirements for defogging functions. These systems involve various components and subcomponents as blowers, thermal exchangers, actuators… with a wide range of well-known technologies and also new ones on newly introduced products. Currently, within established electrification trends worldwide, the HVAC system is becoming the most important embedded system that can induce major contribution of noise and vibration. These NVH issues can emerge through different transfer paths inside the car cabin possibly causing significant discomfort to passengers. During developments, the NVH issues are mastered and contained by both suppliers according to internal standards and OEMs according to specifications compliance. However, OEMs specifications are mainly consisting of overall noise levels and improvements over the years consisting of reduction of these specified levels.

Vehicle weight reduction is important to improve the fuel mileage of ICE vehicles and to extend the range of electric vehicles. Glass fiber reinforced (GFR) Composite(Polyamide) brackets provide significant weight reductions at a competitive part price. Traditionally, metal brackets are designed to surpass a target natural frequency and static stiffness. Composite brackets are inherently less stiff and have lower natural frequencies. However, they also have higher material damping than metal brackets, and good isolation performance can be achieved. The key to integrating the Composite brackets into the vehicle design is to perform adequate analysis to ensure that the noise and vibration performance at the vehicle level meets expectations. In this paper, case studies are presented for three different vehicles - engine roll restrictor bracket (for ICE vehicle), rear differential bracket (for ICE), and rear (electric) motor mount bracket.

Conventional silencers have extensively been used to attenuate airborne pressure pulsations in the breathing system of internal combustion engines, typically at low frequencies as dictated by the crankshaft speed. With the introduction of turbocharger compressors, however, particularly those with the ported shroud recirculating casing treatment, high-frequency tones on the order of 10 kHz have become a significant contributor to noise in the induction system. The elevated frequencies promote multi-dimensional wave propagation, rendering traditional silencing design methods invalid, as well as the standard techniques to assess silencer performance. The present study features a novel high-frequency silencer designed to target blade-pass frequency (BPF) noise at the inlet of turbocharger compressors. The concept uses an acoustic straightener to promote planar wave propagation across arrays of quarter-wave resonators, achieving a broadband attenuation.

Highly compression ratio is effective as one means of improving the thermal efficiency of an internal combustion engine. On the other hand, rapidly rise at combustion pressure to occur because of this high compression ratio causes a highly impulse force. The impulse force gives rise to a vibration and noise by spreading in an engine. Therefore, it can be said that reducing the vibration of combustion, which increases as the compression ratio increases, is same technology with improving thermal efficiency. Regarding the function of reducing combustion vibration, we are conducting model-based research on technology to reduce vibration by applying a granular damper to the piston. To reducing the vibration of combustion efficiently, we attempt to suppress the vibration directly with the piston, which is the source of the vibration. In this way, the damping effect is maximized within the minimized countermeasure range.

This paper describes a simulation methodology developed for gear rattle severity evaluation and drivetrain architecture optimization . The noise generated by gear rattle is one of the main contributors towards customer's overall NVH perception. This study adopts a model-based design approach towards gear rattle phenomenon to simulate the tendency of gear rattle in neutral and drive conditions . Gear rattle simulation model for Tractor driveline developed in 1-D environment and correlated with test data acquired on tractor drivelines for multiple field applications. This analytical physics-based model includes engine torsional signature, clutch damper torsional characteristic and dynamics of traction and PTO driveline. This dynamic simulation model helps to understand and predict the gear rattle severity of various drivetrain architecture early in the product development cycle and assess & Optimize driveline NVH performance.

Low rolling resistance tires are a technology used to improve fuel economy and reduce greenhouse gas emissions in the transportation sector. This project analyzed current relationships between environmental and safety performance properties of commercially available light-duty tire models in Canada. This paper presents the results of a blinded multi-year light-duty vehicle tire research project conducted by Transport Canada & Natural Resources Canada. The study follows on an update to SAE WCX 2018-01-1336 which presented results for tires tested between MY2014-2018. Tire performance was evaluated in a variety of tire categories with a focus on wet grip and rolling resistance. Correlations between key performance indicators were charted to analyze trends in new model tires available on the Canadian tire market. Manufacturer specifications were also charted to evaluate the relations of wet grip and rolling resistance with price, UTQG ratings, and marketing categories.

This study aims to provide an understanding of self-similarity in the turbulent wake generated by a Fastback DrivAer automotive model and assess the impact of upstream disturbances on the wake. The disturbances are generated using a circular cylinder placed five cylinder diameters upstream. Multiple ‘cylinder-model’ positions were tested by offsetting the lateral positioning of the cylinder with respect to the centreline of the model. Data was obtained at cross-planes in the wake going from 25% to 100% car length. Wind tunnel data has been obtained using a total pressure probe rake and a four-hole cobra probe. Data has also been obtained using RANS based simulations with k – ε realisable turbulence model. Mean axial-component velocity profiles were analysed with momentum thickness (θ) and vorticity thickness (δω) used as the scaling parameters. It was seen that self-similarity marginally exists in the wake depending on the upstream conditions and the scaling parameter.

Fatigue analysis of pistons is reliant on an accurate representation of the high temperatures to which they are exposed. It can be difficult to represent this accurately, because instrumented tests to validate piston thermal models typically include only measurements near the piston crown and there are many unknown backside heat transfer coefficients (HTCs). Previously, a methodology was proposed to aid in the estimation of HTCs for backside convection boundary conditions of a stratified charge compression ignition (SCCI) piston. This methodology relies on Bayesian inference of backside HTC using a co-simulation between computational fluid dynamics (CFD) and finite element analysis (FEA) solvers. Although this methodology primarily utilizes the more computationally efficient FEA model for the iterations in the calibration, this can still be a computationally expensive process.

Currently, there are no safe and suitable fuel sources with comparable power density to traditional combustible fuels capable of replacing Internal Combustion Engines (ICEs). For the foreseeable future, civilian and military systems are likely to be reliant on traditional combustible fuels. Hybridization of the vehicle powertrains is the most likely avenue which can reduce emissions, minimize system inefficiencies, and build more sustainable vehicle systems that support the United States Army modernization priorities. Vehicle systems may further be improved by the creation and implementation of artificial intelligence and machine learning (AI/ML) in the form of advanced predictive capabilities and more robust control policies. AI/ML requires numerous characterized and complete datasets, given the sensitive nature of military systems, such data is unlikely to be known or accessible limiting the reach to develop and deploy AI/ML to military systems.

In military applications, diesel engines are required to achieve high power outputs and therefore must operate at high loads. This high load operation leads to high piston component temperatures and heat rejection rates limiting the packaged power density of the powertrain. To help predict and understand these constraints, as well as their effects on performance, a thermodynamic engine model coupled to a finite element heat conduction solver is proposed and validated in this work. The finite element solver is used to calculate crank angle resolved, spatially averaged piston temperatures from in-cylinder heat transfer calculations. The calculated piston temperatures refine the heat transfer predictions as well requiring iteration between the thermodynamic model and finite element solver.

The major area in which the automotive manufacturers are working is to produce high-performance vehicles with lighter weight, higher fuel economy and lower emissions. In this regard, hollow camshafts are widely used in modern diesel and gasoline engines due to their inherent advantages of less rotational inertia, less friction, less weight and better design flexibility. However, the dynamic loads of chain system, valve train and fuel injection pump (if applicable) makes it challenging to design over-head hollow camshafts with the required factor of safety (FOS). In the present work, high-fidelity FE model of a hollow camshaft assembly is simulated to evaluate the structural performance for assembly loads, valve train operating loads, fuel injection pump loads and chain system loads. The investigation is carried out in a high power-density (70 kW/lit) 4-cylinder in-line diesel engine.

The recent introduction of high power Silicon Carbide (SiC) switching devices has enabled electric vehicle (EV) traction inverters to achieve >99% efficiency. The consequentially low heat loss is horrific to vehicle heating-systems designers, since ~200W of power is available, at highway speeds, to heat a liquid coolant -- an order of magnitude less than that necessary to thermally condition High Voltage (HV) battery packs, and is ~40x lower than the peak heating levels needed to warm a passenger cabin.

In automotive air conditioning systems, the oil circulation rate (OCR) is known to affect performance at both the component and system levels. The OCR is the ratio of the mass of the oil in a representative sample of oil-refrigerant mixture from the system to the total mass of the sample taken during steady state operation. With the general industry trend towards low-OCR compressors, the OCR values of interest are getting smaller, and it is becoming increasingly important to acquire an accurate knowledge of OCR for proper system optimization. While there are different OCR measurement techniques available, they all require accurate calibration which is done using the ASHRAE Standard 41.4. The standard describes a sampling technique using an evacuated sampling cylinder with a dead end to draw a sample of oil-refrigerant mixture from the system liquid line.

The author has been conducting research on UV based photocatalytic air purifier systems for the past 5 years to eliminate living organic germs, bacteria, pathogens, etc. from the cabin air. An HVAC system has been developed by using a filter impregnated by titanium di-oxide (TiO2) with UV lights to improve and maintain cabin air quality. The author has designed and constructed a 3rd generation HVAC unit for cabin air purification for automobiles that is based on UV photocatalytic process by using UV-C LEDs to eliminate viruses that typically exist in conditioned space. The author has conducted tests with HVAC unit to determine power consumptions of air purification systems. An HVAC unit that employs a HEPA (high efficiency particulate air filter) filter is compared with the same HVAC unit with UV & titanium dioxide based photocatalytic system. The pressure drops of the HEPA, particulate and TiO2 filters have been investigated that contribute to the overall energy consumption.

High-efficient simulations are mandatory to manage the ever-increasing complexity of automotive powertrain system and reduce development time and costs. Integrating AI methods into the development process provides an ideal solution thanks to massive increase in computational power. Based on an 1D physical engine model of a turbo-charged direct injection gasoline engine with variable valve timing (VVT), a high-performance hybrid simulation model has been developed for increasing computing performance. The newly developed model is made of a physics-based low-pressure part including intake and exhaust peripheries and a neural-network-based high-pressure part for combustion chamber calculations. For the training and validation of the combustion chamber neural networks, a data set with 10.5 million operating points was generated in a short time thanks to the parallelizable combustion chamber simulations in stand-alone mode.

To achieve global climate goals, greenhouse gas emissions must be drastically reduced. The energy and transportation sectors are responsible for about one third of the greenhouse gases emitted worldwide, and they often use internal combustion engines (ICE). One effective way to decarbonize ICEs may be to replace carbon-containing fossil fuels such as natural gas entirely, or at least partially, with hydrogen. Cost-effective development of sustainable combustion concepts for hydrogen and natural gas/hydrogen mixtures in ICEs requires the intensive use of fast and robust simulation tools for prediction. The key challenge is appropriate modeling of flame front propagation. This paper evaluates and applies different approaches to modeling laminar flame speeds from the literature. Both appropriate models and reaction kinetic calculations are considered.