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Over the last two decades, engine research was mainly focused on reducing fuel consumption in view of compliance with more stringent homologation cycles and customer expectations. As it is well known, the objective of overall engine efficiency optimization can be achieved only through the improvement of each element of the efficiency chain, of which mechanical constitutes one of the two key pillars (together with thermodynamics). In this framework, the friction reduction for each mechanical subsystem has been one of the most important topics of modern Diesel engine development. The present paper analyzes the crankshaft potential as contributor to the mechanical efficiency improvement, by investigating the synergistic impact of crankshaft design itself and oil viscosity characteristics (including new ultra-low-viscosity formulations already discussed by the author in [1]).

Over the last two decades, engine research has been mainly focused on reducing fuel consumption in view of compliance with stringent homologation targets and customer expectations. As it is well known, the objective of overall engine efficiency optimization can be achieved only through the improvement of each element of the efficiency chain, of which mechanical constitutes one of the two key pillars (together with thermodynamics). In this framework, the friction reduction for each mechanical subsystems has been one of the most important topics of modern Diesel engine development. In particular, the present paper analyzes the lubrication circuit potential as contributor to the mechanical efficiency improvement, by investigating the synergistic impact of oil circuit design, oil viscosity characteristics (including new ultra-low formulations) and thermal management. For this purpose, a combination of theoretical and experimental tools were used.

The introduction of new light-duty vehicle emission limits to comply under real driving conditions (RDE) is pushing the diesel engine manufacturers to identify and improve the technologies and strategies for further emission reduction. The latest technology advancements on the after-treatment systems have permitted to achieve very low emission conformity factors over the RDE, and therefore, the biggest challenge of the diesel engine development is maintaining its competitiveness in the trade-off “CO2-system cost” in comparison to other propulsion systems. In this regard, diesel engines can continue to play an important role, in the short-medium term, to enable cost-effective compliance of CO2-fleet emission targets, either in conventional or hybrid propulsion systems configuration. This is especially true for large-size cars, SUVs and light commercial vehicles.

Multiple automotive applications exist for small electric motors that are activated by vehicle occupants for various functions such as window lifts and seat adjusters. For such a motor to be described as high quality, not only should the sound it produces be low in amplitude, but it also needs to be free from pulsations and variations that might occur during its (otherwise) steady-state operation. If a motor’s sound contains pulsations or variations between 2 and 8 cycles per second, the variation is described as warble. To establish performance targets for warble noise at both the vehicle and component level a way to measure and quantify the warble noise must be established. Building on existing sound quality metrics such as loudness and pitch variation, a method is established by which processed sound data is put through a secondary operation of Fourier analysis.

With rapid increase of vehicles on the road, safety concerns have become increasingly prominent. Since the leading cause of many traffic accidents is known to be by human drivers, developing autonomous vehicles is considered to be an effective approach to solve the problems above. Although trajectory tracking plays one of the most important roles on autonomous driving, handling the coupling between trajectory-tracking control and ESP under certain driving scenarios remains to be challenging. This paper focuses on trajectory-tracking control considering the role of ESP. A vehicle model is developed with two degrees of freedom, including vehicle lateral, and yaw motions. Based on the proposed model, the vehicle trajectory is separated into both longitudinal and lateral motion. The coupling effect of the vehicle and ESP is analyzed in the paper. The lateral trajectory-tracking algorithm is developed based on the preview follower theory.

The paper describes the challenges and results achieved in developing a new high-speed Diesel combustion system capable of exceeding the imaginative threshold of 100 kW/l. High-performance, state-of-art prototype components from automotive diesel technology were provided in order to set-up a single-cylinder research engine demonstrator. Key design parameters were identified in terms boost, engine speed, fuel injection pressure and injector nozzle flow rates. In this regard, an advanced piezo injection system capable of 3000 bar of maximum injection pressure was selected, coupled to a robust base engine featuring ω-shaped combustion bowl and low swirl intake ports. The matching among the above-described elements has been thoroughly examined and experimentally parameterized.

This paper describes the development of an analytical method to assess and optimize halfshaft joint angles to avoid excessive 3rd halfshaft order vibrations during wide-open-throttle (WOT) and light drive-away events. The objective was to develop a test-correlated analytical model to assess and optimize driveline working angles during the virtual design phase of a vehicle program when packaging tradeoffs are decided. A twelve degree-of-freedom (12DOF) system model was constructed that comprehends halfshaft dynamic angle change, axle torque, powertrain (P/T) mount rate progression and axial forces generated by tripot type constant velocity (CV) joints. Note: “tripot” and “tripod” are alternate nomenclatures for the same type of joint. Simple lumped parameter models have historically been used for P/T mount optimization; however, this paper describes a method for using a lumped parameter model to also optimize driveline working angles.

The wedge clutch takes advantages of small actuation force/torque, space-saving and energy-saving. However, big challenge arises from the varying self-reinforced ratio due to the varying friction coefficient inevitably affected by temperature and wear. In order to improve the smoothness and synchronization time of the slipping process of the wedge clutch, this paper proposes a self-tuning PID controller based on Lyapunov principle. A new Lyapunov function is developed for the wedge clutch system. Simulation results show that the self-tuning PID obtains much less error than the conventional PID with fixed gains. Moreover, the self-tuning PID is more adaptable to the variation of the friction coefficient for the error is about 1/5 of the conventional PID.

Brake systems are strongly related with safety of vehicles. Therefore a reliable design of the brake system is critical as vehicles operate in a wide range of environmental conditions, fulfilling different security requirements. Particularly, countries with mountainous geography expose vehicles to aggressive variations in altitude and road grade. These variations affect the performance of the brake system. In order to study how these changes affect the brake system, two approaches were considered. The first approach was centered on the development of an analytical model for the longitudinal dynamics of the vehicle during braking maneuvers. This model was developed at system-level, considering the whole vehicle. This allowed the understanding of the relation between the braking force and the altitude and road grade, for different fixed deceleration requirement scenarios. The second approach was focused on the characterization of the vacuum servo operation.

This study presents the comparison of vehicle handling performance results obtained using physical test tire data and a tire model developed by means of Finite Element Method. Real tires have been measured in laboratory to obtain the tire force and moment curves in terms of lateral force and align torque as function of tire slip angle and vertical force. The same tire construction has been modeled with Finite Element Method and explicit formulation to generate the force and moment response curves. Pacejka Magic Formula tire response models were then created to represent these curves from both physical and virtual tires. In the sequence, these tire response models were integrated into a virtual multibody vehicle model developed to assess handling maneuvers.

A computational and experimental study was performed to characterize the flow within a gasoline injector and the ensuing sprays. The computations included the effects of turbulence, cavitation, flash-boiling, compressibility, and the presence of non-condensible gases. The flow domain corresponded to the Engine Combustion Network's Spray G, an eight-hole counterbore injector operating in a variety of conditions. First, a rate tube method was used to measure the rate of injection, which was then used to define inlet boundary conditions for simulation. Correspondingly, injection under submerged conditions was simulated for direct comparison with experimental measurements of discharge coefficient. Next, the internal flow and external spray into pressurized nitrogen were simulated under the base spray G conditions. Finally, injection under flashing conditions was simulated, where the ambient pressure was below the vapor pressure of the fuel.

The paper examines how the issue of lengthy development times can be mitigated by adopting a multivariable physics based control method for the development and deployment of complex engine control algorithms required for modern diesel engines equipped with Lean NOx Trap aftertreatment technology. The proposed approach facilitates manufacturers to consider lower cost powertrain configurations for selected markets while maintaining higher performance configurations for other markets. The contribution includes on-engine results from joint work between General Motors and Honeywell. The Honeywell OnRAMP Design Suite which applies model predictive control techniques was used for model identification, control design (using model predictive control) and its calibration. With no prior work on the engine this process of calibrating an engine model and achieving transient drive cycle control on the engine required ten days in the test cell and five days of offline work using the OnRAMP software.

Recent advancements in simulation software and computational hardware make it realizable to simulate a full vehicle system comprised of multiple sub-models developed in different modeling languages. The so-called, co-simulation allows one to develop a control strategy and evaluate various aspects of a vehicle system, such as fuel efficiency and vehicle drivability, in a cost-effective manner. In order to study the feasibility of the synchronized parallel processing in co-simulation this paper presents two co-simulation frameworks for a complete vehicle system with multiple heterogeneous subsystem models. In the first approach, subsystem models are co-simulated in a serial configuration, and the same sub-models are co-simulated in a parallel configuration in the second approach.

In order to increase the efficiency of automotive turbochargers at low speed without compromising the performance at maximum boost conditions, variable geometry compressor (VGC) systems, based on either variable inlet guide vanes or variable geometry diffusers, have been recently considered as a future design option for automotive turbochargers. This work presents a modeling, analysis and optimization study for a Diesel engine equipped with a variable geometry compressor that help understand the potentials of such technology and develop control algorithms for the VGC systems,. A cycle-averaged engine system model, validated on experimental data, is used to predict the most important variables characterizing the intake and exhaust systems (i.e., mass flow rates, pressures, temperatures) and engine performance (i.e., torque, BMEP, volumetric efficiency), in steady-state and transient conditions.

Vehicle dynamics simulation with Hardware In the Loop (HIL) has been demonstrated to reduce development and validation time for dynamic control systems. For dynamic control systems such as Anti-lock Braking System (ABS) and Electronic Stability Control (ESC), an accurate vehicle dynamics performance simulation system requires the Electronic Brake Control Module (EBCM) coupled with the vehicles brake system hardware. This kind of HIL simulation-specific software tool can further increase efficiency by means of automation and optimization of the development and validation process. This paper presents a method for HIL vehicle dynamics simulator optimization through Brake Response Time (BRT) correlation. The paper discusses the differences between the physical vehicle and the HIL vehicle dynamics simulator. The differences between the physical and virtual systems are used as factors in the development of a Design Of Experiment (DOE) quantifying HIL simulator performance.

The friction material is arguably at the heart of any brake system, with its properties taking one of the most important roles in defining its performance characteristics. High performance applications, such as race track capable brake systems in high powered vehicles, exert considerable stress on the friction materials, in the form of very high heat flux loads, high clamp and brake torque loads, and high operating temperatures. It is important, for high performance applications, to select capable friction materials, and furthermore, it is important to understand fully what operating conditions the friction material will face in the considered application.

The GM Aerodynamics Laboratory (GMAL) was modified in 2001 to reduce the background noise level and provide a semi-anechoic test section for wind noise testing. The walls and ceiling of the test section were lined with acoustic foam and foam-filled turning vanes were installed in the corners. Portions of the wind tunnel circuit were also treated with fiberglass material covered by perforated sheet metal panels. High skin drag due to roughness of the foam surfaces, along with high blockage due to the large turning vanes, increased the wind tunnel circuit losses so that the maximum wind speed in the test section was reduced. The present study calculates the averaged total pressure losses at three locations to evaluate the reductions in skin drag and blockage from proposed modifications to the circuit, which were intended to increase the test section wind speed without compromising noise levels.

The unsteady flow fields behind two different automobile outside side rear view mirrors were examined experimentally in order to obtain a comprehensive data base for the validation of the ongoing computational investigation effort to predict the aero-acoustic noise due to the outside rear view mirrors. This study is part of a larger scheme to predict the aero-acoustic noise due to various external components in vehicles. To aid with the characterization of this complex flow field, mean and unsteady surface pressure measurements were undertaken in the wake of two mirror models. Velocity measurements with particle image velocimetry were also conducted to develop the mean velocity field of the wake. Two full-scale mirror models with distinctive geometrical features were investigated.

It is well understood that conditions encountered during racetrack driving are amongst the most severe to which vehicle braking systems can be subjected. High braking pressure is combined with enormous energy input and high temperatures for multiple braking events. Brake fade, degradation of brake pedal feel, and brake lining taper/overall wear are common results of racetrack usage. This paper focuses on how racetrack and high energy driving-type conditioning affects the performance of the brake caliper - in particular, its ability to maintain an even pressure distribution at all of its interfaces (pad to rotor, piston to pad backing plate, and housing to pad backing plate).

The impact of ultra thinwall catalysts on TIER2 emission performance, packaging and total system cost was evaluated. The primary focus was to compare ultra-thinwall and thinwall cell configurations (400/3, 400/4, 600/2, 600/3, 600/3 hex, 900/2, and 1200/2) with a baseline 600/4 at constant substrate volume, washcoat and PGM loading. Other areas investigated included the evaluation of decreasing catalyst volume while maintaining constant or increased mass transfer capabilities while holding washcoat and PGM loadings constant. The emissions impact of varying washcoat and PGM loading was measured on specific substrates, including a comparison of square to hex cell. Backpressure for each configuration was calculated with the Corning substrate pressure drop modeling tool. Converters were rapid aged on dynamometers reflecting approximately a 50,000 mile aged performance. Emission testing was completed using the FTP test cycle.