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In internal combustion engines, the majority of the friction loss associated with the piston takes place on the thrust side in early expansion stroke. Research has shown that the Friction Mean Effective Pressure (FMEP) of the engine can be reduced if proper modifications to the piston skirt, which is traditionally barrel-shaped, are made. In this research, an existing model was applied for the first time to study the effects of different oil supply strategies for the piston assembly. The model is capable of tracking lubricating oil with the consideration of oil film separation from full film to partial film. It is then used to analyze how the optimized piston skirt profile investigated in a previous study reduces friction.

Our studies of the lithium-ion battery system have shown considerably more power capability than some existing batteries. Based on these results, we have developed a lithium-ion battery for parallel hybrid electric vehicle (PHEV) application. This battery system provides around ten times the specific power of conventional batteries and also achieves high recharging performance and high charge/discharge efficiency. Evaluation results indicate that it is a highly promising energy source for PHEVs.

There are two primary technical issues in the application of position sensorless control to generators for 100% electric-drive hybrid vehicles. The first is the risk of losing control when position sensorless estimation methods are changed in accordance with the generator speed, while. The second is the reduction in the maximum torque if the rate of change in the generator speed is extremely large in a relatively low-rotation-speed area. This study proposes countermeasures for each issue and their effects examines them via simulations and experiments.

Mechanisms of NH₃ generation using LNT-like catalysts have been studied in a bench reactor over a wide range of temperatures, flow rates, reformer catalyst types and synthetic exhaust-gas compositions. The experiments showed that the on board production of sufficient quantities of ammonia on board for SCR operation appeared feasible, and the results identified the range of conditions for the efficient generation of ammonia. In addition, the effects of reformer catalysts using the water-gas-shift reaction as an in-situ source of the required hydrogen for the reactions are also illustrated. Computations of the NH₃ and NOx kinetics have also been carried out and are presented. Design and impregnation of the SCR catalyst in proximity to the ammonia source is the next logical step. A heated synthetic-exhaust gas flow bench was used for the experiments under carefully controlled simulated exhaust compositions.

Ground impact caused by road debris can result in very severe fire accident of Electric Vehicles (EV). In order to study the ground impact accidents, a Finite Element model of the battery pack structure is carefully set up according to the practical designs of EVs. Based on this model, the sequence of the deformation process is studied, and the contribution of each component is clarified. Subsequently, four designs, including three enhanced shield plates and one enhanced housing box, are investigated. Results show that the BRAS (Blast Resistant Adaptive Sandwich) shield plate is the most effective structure to decrease the deformation of the battery cells. Compared with the baseline case, which adopts a 6.35-mm-thick aluminum sheet as the shield plate, the BRAS can reduce the shortening of cells by more than 50%. Another type of sandwich structure, the NavTruss, can also improve the safety of battery pack, but not as effectively as the BRAS.

Nissan’s variable compression turbo (VC-Turbo) engine has a multilink mechanism that continuously adjusts the top and bottom dead centers of the piston to change the compression ratio and achieve both fuel economy and high power performance. Increasing the exhaust gas recirculation (EGR) rate is an effective way to further reduce the fuel consumption, although this increases the exhaust gas condensation in the cylinder bores, causing a more corrosive environment. When the EGR rate is increased in a VC-Turbo engine, the combined effect of piston sliding and exhaust gas condensation at the top dead center accelerates the corrosive wear of the thermal spray coating. Stainless steel coating is used to improve the corrosion resistance, but the adhesion strength between the coating and the cylinder bores is reduced.

An investigation has been done on the relationship between spark ignition characteristics and combustion stability in a gasoline engine. The spark discharge parameters examined were the spark current, energy, and duration. It has been found that lengthening the spark discharge duration is particularly effective in achieving stabilized combustion. A longer spark duration provides a continued supply of electric energy as kinetic energy to the mixture around the spark gap. The analytical results of a constant volume combustion chamber test verify that a longer spark duration promotes flame initiation and makes reliable flame propagation possible. The length of the spark duration is regarded as the period from ignition to the onset of combustion pressure rise. The results of a combustion pressure analysis reveal that the spark duration must be longer than the heat release delay.

Engine-out HC emissions from a PFI spark ignition engine were measured using a gas chromatograph and a flame ionization detector (FID). Two port fuel injectors were used respectively for ethanol and gasoline so that the delivered fuel was comprised of 0, 25, 50, 75 and 100% (by volume) of ethanol. Tests were run at 1.5, 3.8 and 7.5 bar NIMEP and two speeds (1500 and 2500 rpm). The main species identified with pure gasoline were partial reaction products (e.g. methane and ethyne) and aromatics, whereas with ethanol/gasoline mixtures, substantial amounts of ethanol and acetaldehyde were detected. Indeed, using pure ethanol, 74% of total HC moles were oxygenates. In addition, the molar ratio of ethanol to acetaldehyde was determined to be 5.5 to 1. The amount (as mole fraction of total HC moles) of exhaust aromatics decreased linearly with increasing ethanol in the fuel, while oxygenate species correspondingly increased.

The purpose of this paper is to clarify the mechanisms of unburnt hydrocarbon (HC) emissions from a small direct - injection (DI) diesel engine. HC emission levels of small DI diesel engines are considerably higher than those of corresponding indirect - injection (IDI) diesel engines, even when sacless injection nozzles that are effective in reducing HC emissions are installed on them. In this study, analytical engine tests were performed to evaluate the relative significance of various potential sources of HC emissions from a small DI diesel engine equipped with sacless type injectors.

The accumulation of soot and lubrication-derived ash particles in a diesel particulate filter (DPF) increases exhaust flow restriction and negatively impacts engine efficiency. Previous studies have described the macroscopic phenomenon and general effects of soot and ash accumulation on filter pressure drop. In order to enhance the fundamental understanding, this study utilized a novel apparatus that of a dual beam scanning electron microscope (SEM) and focused ion beam (FIB), to investigate microscopic details of soot and ash accumulation in the DPF. Specifically, FIB provides a minimally invasive technique to analyze the interactions between the soot, ash, catalyst/washcoat, and DPF substrate with a high degree of measurement resolution. The FIB utilizes a gallium liquid metal ion source which produces Ga+ ions of sufficient momentum to directionally mill away material from the soot, ash, and substrate layers on a nm-μm scale.

The Diesel Particulate Filter (DPF) system has been developed as one of key technologies to comply with tight diesel PM emission regulations. For the DPF control system, it is necessary to maintain temperature inside the DPF below the allowable service temperature, especially during soot regeneration to prevent catalyst deterioration and cracks. Therefore, the evaluation of soot regeneration is one of the key development items for the DPF system. On the other hand, regeneration evaluation requires a lot of time and cost since many different regeneration conditions should be investigated in order to simulate actual driving. The simulation tool to predict soot regeneration behavior is a powerful tool to accelerate the development of DPF design and safe regeneration control strategies. This paper describes the soot regeneration model applied to fuel additive and catalyzed types, and shows good correlation with measured data.

CRT looks promising in achieving clean Diesel emission particularly PM, however, it presents two limits in exhaust gas temperature levels, i.e., at idling to low power region requiring emission temperature 260°C minimum, and at high power region 450°C maximum. These problems can only be solved by the proposed method under the currently available known technologies. At the lower power side, 260°C minimum, can be materialized by the use of “Exhaust Secondary Cam (ESC)”, throttling intake air and exhaust gas lines together with other means like reduction of number of cylinders in operation. At the high power side, 450°C maximum, will easily be cleared by “Hyperbrid supercharging system” invented by the author.

This paper presents a new measurement technique for in-cylinder gas temperature and residual gas concentration during the compression stroke of an internal combustion (IC) engine. This technique is based on the infrared absorption of water vapor by a wavelength modulated laser. Wavelength modulation spectroscopy with second harmonic detection (WMS-2f) was adopted to enable the short-path measurements over a wide range of temperatures and pressures corresponding to the late compression stroke in a typical automotive engine. The WMS-2f signal is detected through a bandpass filter at a width of 7.5 kHz, enabling crank angle-resolved measurements. The temperature is determined from the ratio of optical absorption for two overtone transitions of water vapor in the intake gas mixture, and the H2O concentration is determined from this inferred temperature and the absorption for one of the transitions.

This paper presents the technologies incorporated in an electric vehicle (EV)/hybrid electric vehicle (HEV) inverter built with power semiconductors of silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs) instead of conventional silicon (Si) insulated gate bipolar transistors (IGBTs). A SiC inverter prototype of 2.9 L in size for driving an 80-kW motor was fabricated and evaluated on a motor test bench. The SiC inverter prototype attained average efficiency of 98.5% in the Worldwide harmonized Light-duty Test Cycle (WLTC) driving mode. The two main technologies achieved with this SiC inverter prototype are described. The first one is a new direct-cooled power module with a thick copper (Cu) heat spreader located under the semiconductors that improves thermal resistance by 34% compared with a conventional direct-cooled power module.

Current CJ-4 lubricant specifications place chemical limits on diesel engine oil formulations to minimize the accumulation of lubricant-derived ash in diesel particulate filters (DPF). While lubricant additive chemistry plays a strong role in determining the amount and type of ash accumulated in the DPF, a number of additional factors play important roles as well. Relative to soot particles, whose residence time in the DPF is short-lived, ash particles remain in the filter for a significant fraction of the filter's useful life. While it is well-known that the properties (packing density, porosity, permeability) of soot deposits are primarily controlled by the local exhaust conditions at the time of particle deposition in the DPF, the cumulative operating history of the filter plays a much stronger role in controlling the properties and distribution of the accumulated ash.

Since the VQ engine series of lightweight, compact, low friction and high response engines was released in 1994, they have been rated highly both at home and abroad. Two new 3.0-liter and 3.5-liter V6 engines have been developed as the second generation of the VQ engine and introduced into the North American market. Continuing the characteristics of the first generation, this new VQ engine series achieves a performance figure of 98Nm/L as a result of adopting part shapes defined with a three-dimensional analysis method. The new VQ30DE engine adopts a plastic intake manifold which incorporates a variable induction system with a rotary valve. The new VQ35DE engine adopts a continuously variable valve timing control system and a long branch intake manifold with an inertial induction system. It also incorporates a new concept piston and a hot coined connecting rod to reduce its reciprocating inertial mass.

THE indicated output of a 2-stroke engine is primarily dependent upon the success with which the products of combustion are driven from the cylinder and are replaced by fresh air or mixture during the scavenging period. Such replacement must, of course, be accomplished with a minimum of blower power. This paper deals with various aspects of 2-stroke research conducted at M.I.T. during the past 10 years. Among the subjects discussed are the methods used in the prediction and measurement of scavenging efficiency, and the effect of engine design and operating variables on the scavenging blower requirements as reflected by the scavenging ratio.

This paper presents a new methodology for the safety assessment of complex software intensive systems such as is envisioned for the coming major upgrade of the air traffic management system known as NextGen. This methodology is based on a new, more inclusive model of accident causation called Systems Theoretic Accident Model and Process (STAMP) [1]. STAMP includes not just the standard component failure mechanisms but also the new ways that software and humans contribute to accidents in complex systems. A new hazard analysis method, called Systems Theoretic Process Analysis (STPA), is built on this theoretical foundation. The STPA is based on systems theory rather than reliability theory; it treats safety as a control problem rather than a failure problem with interactive and possibly nested control loops that may include humans. In this methodology, safety is assured by closed loop control of safety parameters.

A variable swirl intake port system for 4 valves/cylinder direct injection diesel engines was developed. This system combines two mutually independent intake ports, one of which is a helical port for generating an ultra-high swirl ratio and the other is a tangential port for generating a low swirl ratio. The tangential port incorporates a swirl control valve that controls the swirl ratio by varying the flow rate. To investigate the performance of the intake port system, steady-state flow tests were conducted in parallel with three-dimensional computations. In conducting the steady-state flow tests, it was found that a paddle wheel flow sensor was not suitable for evaluating the characteristics of the high-swirl port and that it was necessary to use an impulse swirl flow meter.

An investigation was made of the relationship between the driving speed at the time of impact and the injury levels suffered in accidents. The results showed that a 5 km/h or more reduction in collision speed tends to mitigate injury severity. Using sensors and brake actuators already in practical use, we have started to research a braking system aimed at reducing the collision speed by at least 5 km/h in rear-end collisions. The system estimates the risk of a collision with the vehicle ahead. If it judges there is a very high possibility of a collision, it applies the brakes.