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To prevent global warming, further reductions in carbon dioxide are required. It is therefore important to promote the spread of electric vehicles powered by internal combustion engines and electric vehicles without internal combustion engines. As a result, emissions from hybrid electric vehicles equipped with internal combustion engines should be further reduced. Interest in catalytic reactions in an electric field with a higher catalytic activity compared to conventional catalysts has increased because this technology consumes less energy than other electrical heating devices. This study was therefore undertaken to apply a catalytic reaction in an electric field to an exhaust emission control. First, the original experimental equipment was built with a high voltage system used to conduct catalytic activity tests.

This paper presents an improvement in the accuracy of NOx sensors at high NOx concentration regions by optimizing the manufacturing process, sensor electrode materials and structure, in order to suppress the deterioration mechanism of sensor electrodes. Though NOx sensors generally consist of Pt/Au alloy based oxygen pump electrodes and Pt/Rh alloy based sensor electrodes, detailed experimental analysis of aged NOx sensors showed changes in the surface composition and morphology of the sensor electrode. The surface of the sensor electrode was covered with Au, which is not originally contained in the electrode, resulting in a diminished active site for NOx detection on the sensor electrode and a decrease in sensor output. Theoretical analysis using CAE with molecular dynamics supported that Au tends to be concentrated on the surface of the sensor electrode.

The use of exhaust gas recirculation (EGR) in spark ignition engines has been shown to have a number of beneficial effects under specific operating conditions. These include reducing pumping work under part load conditions, reducing NOx emissions and heat losses by lowering peak combustion temperatures, and by reducing the tendency for engine knock (caused by end-gas autoignition) under certain operating regimes. In this study, the effects of EGR addition on knocking combustion are investigated through a combined experimental and modeling approach. The problem is investigated by considering the effects of individual EGR constituents, such as CO2, N2, and H2O, on knock, both individually and combined, and with and without traces species, such as unburned hydrocarbons and NOx. The effects of engine compression ratio and fuel composition on the effectiveness of knock suppression with EGR addition were also investigated.

The effects of high boiling point fuel additives on deposits were investigated in a commercial turbocharged direct injection gasoline engine. It is known that high boiling point substances have a negative effect on deposits. The distillation end points of blended fuels containing these additives may be approximately 15°C higher than the base fuel (end point: 175°C). Three additives with boiling points between 190 and 196°C were examined: 4-tert-Butyltoluene (TBT), N-Methyl Aniline (NMA), and 2-Methyl-1,5-pentanediamine (MPD). Aromatics and anilines, which may be added to gasoline to increase its octane number, might have a negative effect on deposits. TBT has a benzene ring. NMA has a benzene ring and an amino group. MPD, which has no benzene ring and two amino groups, was selected for comparison with the former two additives.

The SEA model of wind noise requires the quantification of both the acoustic as well as the turbulent flow contributions to the exterior pressure. The acoustic pressure is difficult to measure because it is usually much lower in amplitude than the turbulent pressure. However, the coupling of the acoustic pressure to the surface vibration is usually much stronger than the turbulent pressure, especially in the acoustic coincidence frequency range. The coupling is determined by the spatial matching between the pressure and the vibration which can be described by the wavenumber spectra. This paper uses measured vibration modes of a vehicle window to determine the coupling to both acoustic and turbulent pressure fields and compares these to the results from an SEA model. The interior acoustic intensity radiating from the window during road tests is also used to validate the results.

In order to adapt to energy security and the changes of global-scale environment, further improvement of fuel economy and adaptation to each country’s severer exhaust gas emission regulation are required in an automotive engine. To achieve higher power performance with lower fuel consumption, the engine’s basic internal design such as an engine block and cylinder head were changed and the combustion speed was dramatically increased. Consequently, stroke-bore ratio and valve layout were optimized. Also, both flow coefficient and intake tumble ratio port were improved by adopting a laser cladded valve seat. In addition, several new technologies were adopted. The Atkinson cycle using a new Electrical VVT (Variable Valve Timing) and new combustion technology adopting new multi-hole type Direct fuel Injector (DI) improved engine power and fuel economy and reduced exhaust emissions.

New 2A/F systems different from usual A/F-O2 systems are being developed to cope with strict regulation of exhaust gas. In the 2A/F systems, 2A/F sensors are equipped in front and rear of a three-way catalyst. The A/F-O2 systems are ideas which use a rear O2 to detect exhaust gas leaked from three-way catalyst early and feed back. On the other hand, the 2A/F systems are ideas which use a rear A/F sensor to detect nearly stoichiometric gas discharged from the three-way catalyst accurately, and to prevent leakage of exhaust gas from the three-way catalyst. Therefore, accurate detection of nearly stoichiometric gas by the rear A/F sensor is the most importrant for the 2A/F systems. In general, the A/F sensors can be classified into two types, so called, one-cell type and two-cell type. Because the one-cell type A/F sensors don’t have hysteresis, they have potential for higher accuracy.

In recent years, from a viewpoint of global warming and energy issues, the need to improve vehicle fuel economy to reduce CO2 emission has become apparent. One of the ways to improve this is to enhance engine thermal efficiency, and for that, automakers have been developing the technologies of high compression ratio and dilute combustion such as exhaust gas recirculation (EGR), and lean combustion. Since excessive dilute combustion causes the failure of flame propagation, combustion promotion by intensifying in-cylinder turbulence has been indispensable. However, instability of flame kernel formation by gas flow fluctuation between combustion cycles is becoming an issue. Therefore, achieving stable flame kernel formation and propagation under a high dilute condition is important technology.

Engine friction reduction is an effective means to improve fuel consumption. Fluid friction reduction of main bearing is examined for engine friction reduction in cold condition. As one of the examinations, it was focused on low temperature of lubricating oil in the early stage during engine cold start. In hydrodynamic lubrication, the oil film temperature is maintained by balance between heat generation and heat transfer. The heat generation is generated by shear of lubricating oil. The factors of the heat transfer, the following elements are considered as follows, A) The heat transfer to a crank shaft, B) The heat transfer to a bearing, C) The heat transfer by convection. If the heat generation is constant, oil film temperature is increased by reduction of heat transfer. It is considered that the reduction of oil leakage and reduction of the heat transfer by convection is equivalent.

It is important for vehicle concept planning to estimate fuel economy and the influence of vehicle vibration in advance. This can be accomplished using virtual engine specifications and a virtual vehicle frame. In this paper, I will show the power plant model with electric starter and battery that can predict fuel economy, combustion heat results and transient torque. The power plant is a 1.3L 4cyl designed for NA Spark Ignition. The power plant model was realized using an energy based model using VHDL-AMS. Here, VHDL-AMS is modeling language stored in IEC international standard (IEC61691-6) and can realize multi physics in 1D simulation. The modeling language supports electrical, magnetic, thermal, mechanical, fluidic and compressive fluidic domains. The model was created in house using VHDL-AMS and validated on ANSYS SIMPLORER. The simulated results of fuel energy consumption agreed with driving energy and amount of energy losses, e.g. cooling loss, exhaust loss.

Countries and regions around the world are tightening emissions regulations in reaction to the increasing awareness of environmental conservation. At the same time, growing concerns about the depletion of raw materials as vehicle ownership continues to increase is prompting automakers to look for ways of decreasing the use of platinum-group metals (PGMs) in the exhaust systems. This research has developed a new catalyst with strong robustness against fluctuations in the exhaust gas and excellent nitrogen oxide (NOx) conversion performance. This catalyst incorporates rhodium (Rh) clusters with a particle size of several nanometers, and stabilized CeO2-ZrO2 solid-solution (CZ) with a pyrochlore crystal structure as a high-volume oxygen storage capacity (OSC) material with a slow O2 storage rate.

In recent years, enhancing engine thermal efficiency is strongly required. Since the maximum engine thermal efficiency is especially important for HVs, the technologies for improving engine thermal efficiency have been developed. The current gasoline engines for hybrid vehicles have Atkinson cycle with high expansion ratio and cooled exhaust gas recirculation (EGR) system. These technologies contribute to raise the brake engine thermal efficiency to more than 38%.In the near future the consumers demand will push the limit to 40% thermal efficiency. To enhance engine thermal efficiency, it is essential to improve the engine anti-knock quality and to decrease the engine cooling heat loss. To comply with improving the anti-knock quality and decreasing the cooling heat loss, it is known that the cooled EGR is an effective way.

In response to increasing demands for measures to conserve the global environment and the introduction of more stringent CO2 emissions regulations around the world, the automotive industry is placing greater focus on reducing levels of CO2 through the development of fuel-efficient technologies. With the aim of improving fuel economy, a new continuously variable transmission (CVT) has been developed for 2.0-liter class vehicles. This new CVT features various technologies for improving fuel economy including a coaxial 2-discharge port oil pump system, wider ratio coverage, low-viscosity CVT fluid, and a flex start system. This CVT is also compatible with a stop and start (S&S) system that reduces fuel consumption by shutting off the engine while the vehicle is stopped. In addition, the development of the CVT improves driveability by setting both the driving force and engine speed independently.

Improving the engine efficiency to respond to climate change and energy security issues is strongly required. In order to improve the engine efficiency, lower fuel consumption, and enhance engine performance, OEMs have been developing high compression ratio engines and downsized turbocharged engines. However, higher compression ratio and turbocharging cause cylinder pressure to increase, which in turn increases the demand voltage for ignition. To reduce the demand voltage, a new ignition system is developed that uses a high voltage Zener diode to maintain a constant output voltage. Maintaining a constant voltage higher than the static breakdown voltage helps limit the amount of overshoot produced during the spark event. This allows discharge to occur at a lower demand voltage than with conventional spark ignition systems. The results show that the maximum reduction in demand voltage is 3.5 kV when the engine is operated at 2800 rpm and 2.6 MPa break mean effective pressure.

In this paper, a control strategy to switch NSR (NOx storage and reduction) function from standard DeNOx by rich combustion to DiAir (Diesel NOx After-treatment by Adsorbed Intermediate Reductants) and additional advantages to use HCI (Hydrocarbon Injector) during desulfation were introduced. Investigations under a transient cycle suggest that NOx conversion with DiAir is strongly affected by preliminary NOx storage condition in the NSR catalyst. To avoid NOx breakthrough just after starting HC dosing for DiAir, a rich operation to reduce stored NOx was shown to be important and high NOx conversion could be maintained using this control strategy under a transient cycle. Furthermore, by combining HCI and in-cylinder post injection, usage of rich condition for NSR DeSOx can be expand to wider engine speed and load area.

At the engine restart, when the temperature of the catalytic converter is low, additional fuel consumption would be required to warm up the catalyst for controlling exhaust emission.The aim of this study is to find a thermally optimal way to reduce fuel consumption for the catalyst warm up at the engine restart, by improving the thermal retention of the catalytic converter in the cool down process after the previous trip. To make analysis of the thermal flow around the catalytic converter, a 2-D thermal flow model was constructed using the thermal network method. This model simulates the following processes: 1) heat conduction between the substrate and the stainless steel case, 2) heat convection between the stainless steel case and the ambient air, 3) heat convection between the substrate and the gas inside the substrate, 4) heat generation due to chemical reactions.

The advantages of gasoline direct-injection are intake air cooling due to fuel vaporization which reduces knocking, additional degrees of freedom in designing a stratified injection mixture, and capability for retarded ignition timing which shortens catalyst light-off time. Stratified mixture combustion designs often require complicated piston shapes which disturb the fluid flow in the cylinder, leading to power reduction, especially in turbocharged gasoline direct-injection engines. Our research replaced the conventional shell-type shallow cavity piston with a dog dish-type curved piston that includes a small lip to facilitate stratification and minimize flow disturbance. As a result, stable stratified combustion and increased power were both achieved.

Fuel efficiency improvement measures are focusing on both cold and hot conditions to help reduce CO2 emissions. Recent technological trends for improving fuel economy such as hybrid vehicles (HVs), engine start and stop systems, and variable valve systems feature expanded use of low-temperature engine operation regions. Under cold conditions (oil temperature: approximately 30°C), fuel consumption is roughly 20% greater than under hot conditions (80°C). The main cause of the increased friction under cold conditions is increased oil viscosity. This research used the motoring slipping method to measure the effect of an improved crankshaft bearing, which accounts for a high proportion of friction under cold conditions. First, the effect of clearance was investigated. Although increasing the clearance helped to decrease friction due to the oil wedge effect, greater oil leakage reduced the oil film temperature increase generated by the friction.

From the time the first Hybrid Vehicle (HV) was launched, 17 years have past, and HV vehicles have boosted the global CO2 reduction trend. In order to maximize their merit, many HV engines focused on the best fuel consumption value namely thermal efficiency. This was because HV systems can control the operating area of engine and get merit. However, considering climate change and energy issues, it is important to focus conventional vehicle as well as HV vehicle progress. The Atkinson cycle with a high compression ratio is the typical approach that HV engines use to enhance thermal efficiency. However, the drawback of the high compression ratio is a reduction of engine torque. Thermal efficiency at low load areas is relatively more important with conventional engines than with HV engines and how to overcome these issues is significantly important with conventional engines.

Due to increasing demands for further CO2 reduction and tighter exhaust emissions regulations, automakers are increasingly downsizing turbo-charged diesel engines by raising specific power, or adopting low-pressure loop exhaust gas recirculation (LPL-EGR) systems to improve the EGR rate. However, adopting a higher boost pressure to increase the specific power, or introducing hot exhaust gas before the turbocharger compressor with the LPL-EGR system creates higher gas temperatures in the compressor, which results in soot-containing deposits derived from the engine oil in the compressor. This phenomenon causes significant deterioration of turbocharger efficiency. Therefore, countermeasures such as restricting boost pressure or limiting EGR usage in the operational map are necessary to prevent engine performance deterioration. Increasing the gas temperature in the compressor while preventing deposit formation should enable further improvements in fuel consumption and engine power.