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This study investigates if particulates from a GDI engine can be significantly suppressed by use of ultra-high injection pressures under 2 different engine conditions known to be associated with high particulate numbers (PN): warm-up and transients. Experiments were carried out in a single-cylinder GDI engine equipped with an endoscope connected to a high-speed camera to enable combustion visualization. To mimic the warming-up, the coolant temperature was varied between 20 °C and 90 °C. A Diesel injector with modified nozzle was used and the injection pressures were varied between 400 and 1500 bar. The results revealed that increasing the fuel injection pressure decreased engine out HC and PN under warming-up conditions. However, the coolant water temperature was the most dominant factor affecting the emissions. For coolant temperature of 20 °C, the use of 1500 bar fuel injection pressure in comparison to lower fuel pressures resulted in significantly lower PN.

Electronics has greatly contributed to the operation of internal combustion engines. This is especially evident in the benefits that it has brought to drivers, such as enhancing the “Fun to Drive” experience and in reducing the cost of fuel. Moreover, this progress has resulted in minimizing environmental degradation, and yet continuing to support improvements in performance. In the diesel engine, which has superb fuel economy, the innovative progress has been achieved by the common rail technology. The common rail system has the features of high injection pressure control in all engine speed range, highly precise injection control and multiple injections per combustion cycle. The latest 2nd generation of the DENSO common rail system features 1800 bar injection pressure, and five times multiple injection with fully electronic control to ensure precise small injection quantities. This technology has been commercialized into passenger car products in the European market.

This paper describes the reliability of silicon carbide (SiC) MOSFET. We clarified the relation between the lifetime of the gate oxide and the crystal defects. We fabricated MOS diodes using thermal oxidation and measured their lifetimes by TDDB (Time Dependent Dielectric Breakdown) measurement. The wear-out lifetime is sufficient for hybrid vehicle but many MOS diodes broke in shorter time. The breakdown points were defined by Photo-emission method. Finally, we classified the defects by TEM (Transmission Electron Microscopy). A TSD (Threading Screw Dislocation) plays the most important role in the lifetime degradation of the gate oxide. The lifetime of the gate oxide area, in which a TSD is included, is shorter by two orders of magnitude than a wear-out breakdown. The mechanism by which threading dislocations degrade the gate oxide lifetime was not discovered. To explain the degradation, we assumed two models, the shape effect and the oxide quality degradation.

In this paper, we propose a high voltage brushless AC starter that contributes to improved fuel efficiency and a reduction in the cost of the one-motor two-clutch hybrid system, which we call a 1MG2CL system. We have named it the HV starter, and it is composed of an AC motor, inverter and pinion with a shift mechanism. One of the issues with the 1MG2CL system is the high electrical energy when starting an ICE as it switches over from EV drive to HEV drive. While the ICE is starting, the main motor has to crank the ICE via the clutch; the clutch slips to absorb the main motor power, so the main motor has to output a high power to overcome the loss. Therefore, to contribute to reducing the electrical power by eliminating clutch slip losses, we developed an HV starter as a dedicated ICE starting device. Thanks to the reduction in electrical power, the HV starter is able to improve fuel efficiency and reduce system costs.

The Diesel engine performance was drastically improved since the introduction of the Common Rail system in 1996. Over the years, the Common Rail technology was continuously improved to reduce the fuel consumption, engine-out emissions and enhance the drivability. However further technical improvement steps for a precise control of combustion are required to satisfy the increasing stringent worldwide emissions limits and to contribute to attractively performing Diesel powered vehicles. Common Rail injectors significantly contribute to improve the combustion. This improvement can be achieved by precisely controlling the injected fuel quantity and increasing the injection pressure. In addition to those features, a more rectangular injection rate, the capability of stable multiple injections at shorter intervals and the control of the spray shape, are required to achieve an optimized fuel mixture.

According to the advance of engine control development, demands for direct sensing of physical quantity have been growing. Regarding pressure sensing, key properties for direct sensing are robustness against high temperature and pressure, and response time in addition to accuracy. In this work, a pressure sensor module with these key properties was developed. First of all, a piezoelectric device was selected as a suitable sensing principle for the required properties because of its thermally stable piezoelectric effect and potential for simple installation structure. Regarding robustness against temperature, the sensor module was designed to form thermal isolation layer with outer housing which is optimized according to its application. Regarding robustness against pressure and response time, breakage of the piezoelectric element is the main technical issue.

Gasoline direct injection (GDI) systems are a main development focus for global environment issues and energy security. At the same time, it is also important to challenge further development of Multi point injection (MPI) systems for a simple and robust combustion system responding to global fuels ,required for the growing automotive markets in emerging countries, especially in the A, B vehicle segments. This paper focuses on reducing wall wetting in cold conditions and maximizing mixture cooling by fuel vaporization (preventing knocking) in high load conditions as key development points of MPI systems. We propose a dual MPI system enhancing direct flow of spray into the combustion chamber to gain part of the benefit of GDI in addition to the homogeneity advantage of an MPI system. This dual MPI system requires finer atomization with at the same time robustness against intake airflow.

In SI engines with port injection system, the injected fuel spray adheres surely on the port wall and the inlet valve, consequently, the spray-wall interaction process leads to the generation of unburned hydrocarbons and uncontrollable mixture formation. This paper deals with the fuel mixture preparation process including basic research on characteristics of the wall-wetted fuel film on a flat wall inside a constant volume vessel. In the experiments, iso-octane mixed with biacetyl as a tracer dopant was injected through a pintle type injector against a flat glass wall under the ambient conditions of atmospheric pressure and room temperature. The thickness of the adhered fuel film on the wall was quantitatively measured by using laser induced fluorescence (LIF) technique, which provides 2-D distribution information with high special resolution as a function of the injection duration, the impingement distance from the injector to the wall, and the impingement angle against the wall.

One of the main features of 48 V vehicles is the ability to coast at high speeds with the Internal Combustion Engine (ICE) off. This can be realized due to the high torque and power the 48 V motor-generator provides which allows a quick and smooth re-cranking of the ICE. The coasting feature reduces the fuel consumption depending on frequency and duration of the coasting events. This depends in turn on driving pattern, driving style, State-of-Charge of the 48 V and 12 V batteries and the air-conditioning (A/C) system. In summer, if the A/C runs with a mechanical belt-driven compressor, the cabin inlet air temperature from the evaporator inevitably increases during each coasting event as the ICE turns off and cannot operate the compressor. If the evaporator temperature reaches a certain threshold at which the cabin comfort is noticeably affected, the ICE is re-cranked for resuming air-conditioning.

Tightening global emissions standards are driving automotive Original Equipment Manufacturer’s (OEM’s) to utilize Three Way Catalyst (TWC) aftertreatment systems that can perform with greater efficiency and greater measured control of Precious Group Metals (PGM) use. At the same time, TWC aftertreatment systems minimize exhaust system pressure drops. This study will determine the influence of catalyst substrate cell geometry on emission and PGM usage. Additionally, a study of lightoff and backpressure comparisons will be conducted. The two substrate configurations used are hex/750cpsi and square/750cpsi.

With the global adoption of diesel common rail systems and the wide variation in composition of local commercial fuels, modern fuel injection systems must be robust against diverse fuel properties. To bridge the knowledge gap on the effects of compositional variation for real commercial fuels on spray combustion characteristics, the present work quantifies ignition and soot formation/oxidation in three unique, international diesel blends. Schlieren imaging, excited-state hydroxyl radical (OH*) chemiluminescence imaging and diffused back-illumination extinction imaging were employed to quantify vapor penetration, ignition, and soot formation and oxidation for high-pressure sprays in a constant-volume, pre-burn chamber. The three fuels were procured from Finland, Japan and Brazil and have cetane numbers of 64.1, 56.1 and 45.4, respectively.

An ignition simulation and an ignition visualization method that analyze effects of spark plug electrode design have been developed. In the ignition simulation, a programmed heat source corresponds to the discharge energy in the spark gap, and the flame-kernel generation and flame propagation are calculated on the heat balance in the gap, in consideration of thermal transmission to the electrodes. The results by this simulation indicate that high ignitability of fine ground electrode spark plugs is because the miniaturization of the ground electrode reduces the heat loss, and flame growth is thus less disturbed by the loss. The ignition visualization includes taking Schlieren images by laser light to capture flame kernels with weaker luminescence intensity compared to ignition discharge spark luminescence. This visualization enables the observation of the influence of the shape of spark plug electrodes on flame growth.

Reducing the loss of the power control unit (PCU) in a hybrid vehicle (HV) is an important part of improving HV fuel efficiency. Furthermore the loss of power devices (insulated gate bipolar transistors (IGBTs) and diodes) used in the PCU must be reduced since this amounts to approximately 20% of the total electrical loss in an HV. One of the issues for reducing loss is the trade-off relationship with reducing voltage surge. To restrict voltage surge, it is necessary to slow down the switching speed of the IGBT. In contrast, the loss reduction requires the high speed switching. One widely known method to improve this trade-off relationship is to increase the gate voltage in two stages. However, accurate and high-speed operation of the IGBT gate control circuit is difficult to accomplish. This research clarifies a better condition of the two-stage control and designed a circuit that improves this trade-off relationship by increasing the speed of feedback control.

In general, CFD analysis with porous media is precise enough to simulate airflow behavior in a heat exchanger core, placed in the vehicle. In a case when the airflow behavior is complex, however, the precision lowers according to our study. Therefore, we developed a new modeling method to keep high-precision and applied it to analysis of airflow in the vehicle. The concept is at first that the shape of tubes and the distance between the tubes are as the actual product so that the airflow with an oblique angle is to pass through a core. With this concept, airflow with an oblique angle hits the surface of tubes and passes through a core with changing the direction. Next, the concept is to reproduce the air pressure loss in actually-shaped fins, and therefore, we use a porous medium for the modeling of the fins instead of the product shape modeling to combine with the the tubes.

It is important that Advanced Driver Assistance Systems (ADAS) and Automated Driving Systems (AD) detect on-road objects, road vehicles and pedestrians. The typical detection devices mounted on ADAS and AD include a camera, a millimeter-wave radar and a Light Detection And Ranging (LiDAR). Since LiDAR can obtain accurate distance and fine spatial resolution due to its short wavelength, it is expected that small objects such as a tire can be detected. However, the conventional LiDAR is equipped with multiple light transmitters and light receivers such as avalanche photo diodes. This causes LiDAR system to be expensive and large in size. Aiming to reduce the cost and size of LiDAR, we employed Single-Photon Avalanche Diode (SPAD) which can be fabricated by CMOS process and easily arrayed. We also developed “Single Chip SPAD Array“ in which the two-dimensional array of SPAD and a signal processing block of range calculation were integrated into a single chip.

Combustion-pressure-data-based feedback control of fuel injection and EGR is the most promising diesel system, since it can reduce fuel consumption and emissions, as well as noise and vibration, and improve the evaluation efficiency for adapting engine performance to. We developed a combustion pressure sensor installed inside the glow plug. This is superior in maintainability and ease of installation, and can detect the combustion pressure in each cylinder at high accuracy and low cost, with no need for engine modification.

Continuous improvement of gasoline engine emissions performance is required to further protect the global environment and also the impact of emissions on a local level. During real world driving, transient engine operation and variation in fuel injection, airflow, and wall temperature are key factors to be controlled. Due to the limited opportunity for optimization of engine control, generation of a well-mixed fuel spray is necessary to create a suitable combustion environment to minimize emissions. Optimum spray performance achieves minimum surface wetting as well as promoting evaporation and diffusion if wetting occurs. Improvement in spray homogeneity is an important step to achieve this. Higher fuel pressure is initially considered to achieve improvements, as it is expected to improve mixture formation by reduction of wall wetting due to high atomization and lower penetration, as well as improvement in spray homogeneity.

This study reports on a new generation ECS (Ejector Cycle System) which includes a highly efficient ejector and a novel system configuration. The ejector is working as a fluid jet pump that recovers expansion energy which is wasted in the conventional refrigeration cycle decompression process, and converts the recovered expansion energy into pressure energy and raises the compressor suction pressure. Consequently, the ejector system can reduce power consumption of the compressor by using the above mentioned pressure-rising effect and improve energy efficiency of the refrigeration cycle. The ejector consists of a nozzle, a suction section, a mixing section and a diffuser. The objective of this study is to improve actual fuel economy of all vehicles by ejector technology. The previous generation ECS was reported in 2012 SAE World Congress1. Now, a new generation ECS has been successfully developed and released in the market for Mobile Air Conditioning systems as of 2013.

In gasoline direct injection (GDI) systems, various injection types are needed to reduce emissions and improve fuel consumption. This requires high-precision injection in the region in which the amount of injection is small. Achieving injection of a small amount of fuel using GDI solenoid injectors requires the use of the half-lift region. In this region, however, the variation in the injection amount tends to increase due to the variation in the lift behavior of the injectors, posing the problem of how to achieve high-precision injection. To reduce the variation, we analyzed the lift timing out of the injector current and voltage signal with the ECU in an attempt to adjust the amount of injection.

An important function of an Automated Driving (AD) system is to detect objects including vehicles and pedestrians on the road. Typical devices for detecting those objects include cameras, millimeter-wave RADAR, and light detection and ranging (LiDAR). LiDAR uses the flight time of a short-wavelength electromagnetic wave. Because of that LiDAR is expected to find even small objects such as tire fragments on a road in high resolution. The detection performance required for LiDAR depends on the operational design domain (ODD). For example, while a vehicle is travelling at high speeds, LiDAR needs to detect apparently small objects at long distances, and while it is travelling at low speeds, LiDAR has to detect objects over a wide angular range. Conventional LiDAR is developed to satisfy all requirements, providing performance including detection distance, resolution, and angle of view tends to expose issues such as cost and size when it is mounted onboard.