Turbocharging is rapidly becoming an integral part of many internal combustion engine systems. While it has long been a key to diesel engine performance, it is increasingly seen as an enabler in meeting many of the efficiency and performance requirements of modern automotive gasoline engines. This web seminar will discuss the basic concepts of turbocharging and air flow management of four-stroke engines. The course will explore the fundamentals of turbocharging, system design features, performance measures, and matching and selection criteria.
The three major objectives of a car design are reduced costs, maximized performance and improved fuel economy. The total mass of a car has a direct effect on all these three objectives. Around 25% of the total mass of a typical car is accumulated in its Body-In-White (BIW). Thus, reducing the total mass of the BIW while satisfying the target stiffness is of utmost importance in the early stages of design. Reducing the total mass of the BIW involves the identification of potential sites for mass reduction and stiffness improvement. The joints of the BIW are often the most critical locations that decide the overall stiffness of the BIW. Understanding the contribution of each joint towards the overall stiffness is thus of paramount importance towards improving the stiffness of the BIW. This paper describes a new approach of identifying the contribution of each joint in a BIW towards the overall stiffness of the BIW.
Variable Displacement Oil Pump (VDOP) is becoming the design of choice for engine friction reduction and fuel economy improvement. Unfortunately, this pump creates excessive pressure ripples, at the outlet port during oil pump shaft rotation, causing oscillating forces within the lubrication system and leading to the generation of objectionable tonal noises and vibrations. In order to minimize the level of noise, different vanes spacing and porting geometries are used. This paper presents an optimization method to identify the best geometry of the oil pressure relief groove. The method integrates adaptive meshing, 3D CFD simulation, Matlab routine and Genetic Algorithm based optimization. The genetic algorithm is used to create the required design space in order to perform a multi-objective optimization using a large number of parameterized groove geometries. Results of this optimization method are discussed and a design guideline for the oil pressure relief groove is disclosed.
Cylinder deactivation has been in use at Fiat Chrysler Automobiles for several years resulting in a fuel economy advantage for V8-powered vehicles. The size of the fuel-economy benefit, compared to the full-potential possible, is often limited due to the amount of usable torque available in four-cylinder-mode being capped by Noise, Vibration, and Harshness (NVH) sensitivities of various rear-wheel-drive vehicle architectures. This paper describes the application and optimization of active vibration absorbers coupled with interior active noise control, optimized as a system, to attenuate vibration through several paths from the powertrain-driveline into the vehicle. The use of this strategy for attenuating vibration at strategic points is shown to diminish the need for reducing the powertrain source vibration amplitude.
Modern engines have high torque outputs and have low RPM due to increased demand for fuel efficiency. Such engines have high vibration and must be mitigated for customer comfort. Decoupling the roll mode from the remaining five rigid body modes results in a vibratory response which is predominantly about the torque roll axis (TRA). Therefore, placing the mounts on the TRA early in the design phase is crucial. Best NVH performance can be obtained by optimizing the powertrain mount parameters like position, orientation and stiffness. Many times, packaging restricts the mounts to be placed about the TRA resulting in degradation in NVH performance. Assuming that the engine mounts cannot be moved, let the desired TRA be the line through the existing engine mount (body side) centers. We propose a novel method of shifting the TRA by adding mass modifying the powertrain inertia such that the new TRA is parallel to and on top of the desired TRA.
This paper focuses on partial encapsulation technique for reducing air-borne noise from the rocker cover of a commercial vehicle diesel engine. Due to increasing awareness, customers demand for improvised NVH-Noise Vibration and Harshness performance in modern day vehicles. Better NVH performance implies better comfort for passengers as well as vehicle operator. This further increases the driver up time due to reduced driver fatigue. In order to improve NVH performance of existing vehicle and observe different noise and vibration zones, detailed noise and vibration mapping was carried out on one of our vehicle platform. It is observed that engine noise is one of the major contributors for interior noise, apart from road inputs etc.
Developing vehicles that achieve optimum fuel economy and acceleration performance is critical to the success of any automotive company, yet many practicing engineers have not received formal training on the broad range of factors which influence vehicle performance. This seminar provides this fundamental understanding through the development of mathematical models that describe the relevant physics and through the hands-on application of automotive test equipment. Attendees will also be introduced to software used to predict vehicle performance.
Improving vehicular fuel efficiency is of paramount importance to the global economy. Governmental regulations, climate change and associated health concerns, as well as the drive towards energy independence, have created a technical need to achieve greater fuel efficiency. While vehicle manufacturers are focusing efforts on improved combustion strategies, smaller displacement engines, weight reduction, low friction surfaces, etc., the research involved in developing fuel efficient engine oils has been less publicized.
Variable Compression Ratio systems are an increasingly attractive solution for car manufacturers in order to reduce vehicle fuel consumption. By having the capability to operate with a range of compression ratios, engine efficiency can be significantly increased by operating with a high compression ratio at low loads, where the engine is normally not knock-limited, and with a low compression ratio at high load, where the engine is more prone to knock. In this way, engine efficiency can be maximized without sacrificing performance. This study aims to analyze how the effectiveness of a VCR system is affected by various powertrain and vehicle parameters. By using a Matlab model of a VCR system developed in Part 1 of this work, the influence of the vehicle characteristics, the drive cycle, and of the number of stages used in the VCR system was studied.
Cooperated with a local Chinese brand, Geely, the goal of this research is to improve the thermal efficiency on an extremely downsized 3-cylinder 1.0 L turbocharged GDI engine. Effects of compression ratio, low pressure cooled EGR, valve timing and viscosity of oil on fuel economy were studied. The results show that increasing compression ratio (from 9.6 to 12) can improve fuel economy at relative low load (below 12 bar BMEP), but has negative effect at high load due to increased knock intensity. EGR can significantly reduce the pumping loss at low load, optimize combustion phase and reduce exhaust gas temperature. Therefore, the fuel consumption is decreased at all test points. The average brake thermal efficiency (BTE) benefit percentage is 3.47% with 9.6 compression ratio and 5.33 % with 12 compression ratio. However, at higher load (over 18bar BMEP), EGR needs to be reduced to reach the target load, which would affect its beneficial to efficiency.
This paper presents the thermal management of a hybrid vehicle (HV) by using a heat pump system in cold weather. The advantage of an HV is a high efficiency of the vehicle system since an electric motor and an engine are coupled and optimally controlled. However, in the conventional HV, we see the fuel economy degradation in cold weather because delivering heat to the passenger cabin by using an engine results in a low efficiency of the vehicle system. To improve the fuel economy degradation, in this study, a heat pump is used and combined with an engine for the thermal management. The heat pump with an electrically driven compressor pumps heat from ambient into a water-cooled condenser. The heat which is generated by the engine and the heat pump is delivered to the engine and the passenger cabin because the engine needs to warm up quickly to reduce the emission and the cabin needs heat for thermal comfort.
Vehicle weight reduction through the use of components made of magnesium alloys is an effective way to reduce carbon dioxide emission and improve fuel economy. In the design of these components, which are mostly under cyclic loading, notches are inevitably present. In this study, surface strain distribution and crack initiation sites in the notch region of AZ31B-H24 Mg alloy specimens under uniaxial load are recorded via digital image correlation. Predicted strains from finite-element analysis using LS-DYNA material types 124 (MAT_PLASTICITY_COMPRESSION_TENSION) and 233 (MAT_CAZACU_BARLAT) are compared against experimental measurements during quasi-static and cyclic loadings. It is concluded that MAT_233, when calibrated using cyclic tensile and compressive stress-strain curves, is capable of predicting strain at the notch root.
The availability of connectivity and autonomy enabled resources to the automotive sector, has primarily been considered for driver assist technologies (DAT) and for extending the levels of vehicle autonomy. It is clear, however, that the additional information available from connectivity and autonomy, may also be useful in further improving powertrain functions. Additionally, critical subsystems that must operate with limited or uncertain knowledge of their environment stand to benefit from such new information sources. In this paper we discuss one such system, the Diesel Particulate Filter (DPF). Standard DPF regenerations are scheduled on some soot load inference based on indirect indicators of system state, such as exhaust gas flow rate and pressure drop across the DPF. Approaches such as this are necessary since a reliable method of a direct soot load measurement in the DPF is currently not available.
Toyota Motor Corporation has developed an innovative AWD system called "Dynamic Torque Vectoring AWD" for FF-based AWD vehicles.The Dynamic Torque Vectoring AWD is a significant contributor to the excellent dynamic performance and fuel efficiency of New RAV4. A very unique and compact new disconnect mechanism is in each used the transfer and rear differential unit, the rotation of the propeller shaft is completely stopped when unnecessary, contributing to the overwhelming fuel economy improvement. In addition, by utilizing the electronically controlled coupling independently on the left and right sides of the rear differential, it is possible to distribute the torque of the rear wheels independently, thereby greatly improving the on-road steering performance and off-road driving performance.
With continued industry focus on reducing parasitic transmission and driveline losses, detailed studies are required to quantify potential enablers to improve vehicle fuel economy. Investigations were undertaken to understand the influence of lower viscosity Automatic Transmission Fluids (ATF) on transmission efficiency as compared with conventional fluids. The objectives of this study were to quantify the losses of lower viscosity ATF as compared with conventional ATF, and to understand the influence of ATF properties including viscosities, base oil types, and additive packages on fuel efficiency. The transmission efficiency investigations were conducted on a test bench following a vehicle-based break-in of the transmission using a prescribed drive cycle on a chassis dynamometer. At low temperature, the lower viscosity ATF showed a clear advantage over the conventional ATF in both spin loss and loaded efficiency evaluations.
The confluence of fuel economy improvement requirements and increased use of ethanol as a gasoline blend component has led to various studies into the efficiency and performance benefits of using high octane number, high ethanol content fuels in modern engines. As part of a comprehensive study of the autoignition of fuels in both the CFR octane rating engine and a modern, direct injection, turbocharged spark ignited engines, a series of fuel blends were prepared with market-relevant ranges for octane numbers and ethanol blends levels. The paper reports on the first part of this study where fuel flow measurements were done on a single cylinder research engine, based on a GM LHU engine. For a range of engine speeds and manifold air pressures, spark timing was adjusted to achieve either the maximum brake torque (MBT) or a matched 50% mass fraction burned location.