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Exhaust and evaporative emissions systems have been developed to match the characteristics and usage of the Toyota THS II plug-in hybrid electric vehicle (PHEV). Based on the commercially available Prius, the Toyota PHEV features an additional external charging function, which allows it to be driven as an electric vehicle (EV) in urban areas, and as an hybrid electric vehicle (HEV) in high-speed/high-load and long-distance driving situations. To reduce exhaust emissions, the conventional catalyst warm up control has been enhanced to achieve emissions performance that satisfies California's Super Ultra Low Emissions Vehicle (SULEV) standards in every state of battery charge. In addition, a heat insulating fuel vapor containment system (FVS) has been developed using a plastic fuel tank based on the assumption that such a system can reduce the diffusion of vapor inside the fuel tank and the release of fuel vapor in to the atmosphere to the maximum possible extent.

The effects of an increasing boost pressure, a high EGR rate and a high injection pressure on exhaust emissions from an HSDI (High Speed Direct Injection) diesel engine were examined. The mechanisms were then investigated with both in-cylinder observations and 3DCFD coupled with ϕT-map analysis. Under a high-load condition, increasing the charging efficiency combined with a high injection pressure and a high EGR rate is an effective way to reduce NOx and soot simultaneously, which realized an ultra low NOx of 16ppm at 1.7MPa of IMEP (Indicated Mean Effective Pressure). The flame temperature with low NOx and low soot emissions is decreased by 260K from that with conventional emissions. Also, the distribution of the fuel-air mixture plot on a ϕT-map is moved away from the NOx and soot formation peninsula, compared to the conventional emissions case.

In this study, we combined a diesel engine with the Toyota Hybrid System (THS). Utilizing the functions of the THS, reducing engine friction, lowering the compression ratio, and adopting a low pressure loop exhaust gas recirculation system (LPL-EGR) were examined to achieve both low fuel consumption and low nitrogen oxides (NOx) emissions over a wide operating range. After applying this system to a test vehicle it was verified that the fuel economy greatly surpassed that of a conventional diesel engine vehicle and that NOx emissions could be reduced below the value specified in the Euro 6 regulations without DeNOx catalysts.

A new automatic transmission, engineered from concept for “intelligent” and “anti-aging” (long life), has been designed and developed for TOYOTA's luxury passenger car, LEXUS LS400. This system, which has resulted in silky-smooth shift quality without changes in the long term, is composed of a transmission computer that interacts with engine computer, a number of sensors, an electronically controlled hydraulic unit with linear solenoid valves and assorted devices. As new control logic being developed with the aid of computer simulation to achieve distinction, the hydraulic and engine controls are combined in this system. There is a “feedback control”, where the clutch pressure is controlled according to the rate of acceleration and compensated for dispersion to applied pressure, engine torque and/or the coefficient of dynamic friction of clutches, and at the same time engine torque is reduced by retarding ignition timing.

The impact of fatty acid methyl ester (FAME) blended diesel fuel on engine/vehicle systems was comprehensively investigated by vehicle, laboratory and engine tests. In this study, 20% FAME blended fuel (B20) was mainly used and soy bean oil methyl ester (SME) was primarily selected as the FAME. Vehicle testing with long-term fuel storage in vehicle fuel tanks was conducted, considering the most severe conditions in market use. Laboratory and engine tests were also conducted to better understand the vehicle test results. In the vehicle test, engine startability, idle roughness and fuel injection control were evaluated using nine vehicles with plastic or metal fuel tanks. All vehicles showed no problems up to 7 months. While five vehicles with plastic fuel tank did not show any problems throughout the test period up to 18 months, four vehicles with metal fuel tanks experienced malfunctions in engine start or fuel injection control following 8, 13, 13 and 18 months respectively.

In Biodiesel Fuel Research Working Group(WG) of Japan Auto-Oil Program(JATOP), some impacts of high biodiesel blends have been investigated from the viewpoints of fuel properties, stability, emissions, exhaust aftertreatment systems, cold driveability, mixing in engine oils, durability/reliability and so on. This report is designed to determine how high biodiesel blends affect oil quality through testing on 2005 regulations engines with DPFs. When blends of 10-20% rapeseed methyl ester (RME) with diesel fuel are employed with 10W-30 engine oil, the oil change interval is reduced to about a half due to a drop in oil pressure. The oil pressure drop occurs because of the reduced kinematic viscosity of engine oil, which resulting from dilution of poorly evaporated RME with engine oil and its accumulation, however, leading to increased wear of piston top rings and cylinder liners.

An on-board particulate matter (PM) sensor, consisting of a gas-permeable electrochemical cell with a porous yttria-stabilized zirconia solid oxide electrolyte, was developed to assist the on-board diagnostics (OBD) system of a vehicle. Exhaust is pumped from the anode side to the cathode side and PM deposited on the anode is instantly oxidized by the catalytic effects of the metal component of the electrode at temperatures higher than 350°C. The PM oxidation reaction occurs at the three-phase boundary between the anode, electrolyte and gas phase, and causes a slight change in the bulk average oxygen concentration, which produces electrochemical polarization by the difference in oxygen partial pressures between the anode and cathode. The developed PM sensor has a detection limit of 2 mg/m₃, at which level will enable PM detection in the OBD system according to the EURO VI regulation.

In order to clarify the diesel fuel spray characteristics inside the cylinder, we developed two novel techniques, which are preparation of same level of temperature and pressure ambient as inside cylinder and quantitative measurement of vapor concentration. The first one utilizes combustion-type constant-volume chamber (inner volume 110cc), which allows 5 MPa and 873K by igniting the pre-mixture (n-pentane and air) with two spark plugs. In the second technique, TMPD vapor concentration is measured by using Laser Induced Exciplex Fluorescence method (LIEF). The concentration is compensated by investigation of the influence of ambient pressure (from 3 to 5 MPa) and temperature (from 550 to 900 K) on TMPD fluorescence intensity. By using two techniques, we investigated the influence of nozzle hole diameter, injection pressure and ambient condition on spray characteristics.

Premixed diesel combustion modes including low temperature combustion and MK combustion are expected to realize smokeless and low NOx emissions. As ignition must be delayed until after the end of fuel injection to establish these combustion modes, methods for active ignition control are being actively pursued. It is reported that alcohols including methanol and ethanol strongly inhibit low temperature oxidation in HCCI combustion offering the possibility to control ignition with alcohol induction. In this research improvement of diesel combustion and emissions by ethanol intake port injection for the promotion of premixing of the in-cylinder injected diesel fuel, and by increased EGR for the reduction of combustion temperature.

In order to correspond to the exhaust emissions regulations that become severe every year, more advanced engine control becomes necessary. Engine engineers are concerned about the Hydrocarbons (HCs) that flow through the air-intake ports and that are difficult to precisely control. The main sources of the HCs are, the canister purge, PCV, back-flow gas through the intake valves, and Air / Fuel ratio (A/F) may be aggravated when they flow into the combustion chambers. The influences HCs give on the A/F may also grow even greater, which is due to the increasingly stringent EVAP emission regulations, by more effective ventilation in the crankcase, and also by the growth of the VVT-operated angle and timing, respectively. In order to control the A/F more correctly, it is important to estimate the amount of HCs that are difficult to manage, and seek for suitable controls over fuel injection and so on.

CARB (California Air Resources Board) has required the evaporative emissions to be restricted to 1/4th of the parameter stated in the 1995 regulations. Furthermore, hydrocarbons (hereafter, HC) from the fuel system must be reduced to near 0.0 grams, according to the PZEV (Partial Zero Emission Vehicle) regulations enforced from 2003. The wet film in intake ports and fuel leaking from the injector nozzles evaporate and diffuse while the car is parked, and consequently may cause HC to leak the air cleaner inlet. The air cleaner which prevents HC leakage from the air intake system is already in mass production. In the course of designing this product to be installed in a vehicle, the authors developed a method to estimate the amount of HC that reaches the air cleaner. Based on detailed investigation on HC distribution and the changes that occur during parking, the HC amount reaching the air cleaner was calculated by both the equation of diffusion and the equation of state.

A new stratified charge system has been developed for direct injection gasoline engines. The special feature of this system is employment of a thin fan-shaped fuel spray formed by a slit nozzle and a shell-shaped piston cavity. This system, basically classified into the wall-guided mixture preparation concept that leads air/fuel mixture to the spark plug periphery by means of spray penetration and piston cavity configuration without an extra intake air flow controlling system, obtained wide engine operating area with stratified combustion and high output performance. This report presents the characteristics of stratified mixture formation and combustion, especially the important factor for achieving stable stratified combustion in the high-speed region, which have been clarified through analytical studies.

An experimental study was carried out in order to reduce engine-out HC emissions from a direct injection spark ignition (DISI) engine during the cold start period. The objectives of this study were to investigate the fuel behavior quantified with an analytic method and to propose some practical techniques to reduce the cylinder-wetting fuel volume and engine-out HC emissions. Compared to the MPI (Multi Port Fuel Injection) engine, required fuel volume for DISI engine was reduced during the cold start because intake port wall-wetting was not generated. On the other hand, a large volume of cylinder wetting fuel resulted in engine-out HC emissions. Injection timing, atomization and vaporization of injected fuel affected the cylinder-wetting fuel volume. Above all, Injection of the heated fuel provided good results. In summary, engine-out HC emissions from DISI engine was reduced compared to that of MPI engine during the cold-start period.

The Vapor Reducing Fuel Tank System (Bladder Tank System) using a flexible plastic membrane (Bladder Membrane) was newly developed in order to reduce the amount of vaporized gasoline in a steel fuel tank. This Bladder Membrane is flexible to expand in proportion to a fuel volume and prevents the permeation of the vaporized gasoline. As a result of our initial study for various materials, we decided to apply a multi-layer plastic material which could achieve both low fuel permeability and good flexibility. This multi-layer material consists of polyethylene(PE) for structural material and polyamide(PA) for low permeability. The modulus of the PE needs to achieve a sufficient flexibility in order to keep the movement of the membrane. While PA material must have not only low fuel permeability but also strong adhesion with the structural material of PE. We also clarify the membrane design to keep a good flexibility and to reduce a strain.

Methanol steam reforming, which is an endothermic reaction, needs some heating. Both methanol conversion ratio and carbon monoxide (CO) concentration increase when temperature is elevated. As CO poisons a typical polymer electrolyte of a fuel cell, the relationship between methanol conversion ratio and CO concentration is a trade-off one. It was found from preliminary researches that the reforming reaction speed is controlled by heat transfer rate at large methanol flow rate, where methanol conversion ratio becomes lower and CO concentration becomes higher. Therefore it is necessary to develop a new methanol reforming concept that provides stable combustion for heating and enhanced heat transfer for improving the trade-off relationship and making a compact reformer. Reforming catalyst using metal honeycomb support and a new catalytic combustion were applied to a new concept plate type methanol steam reformer, which is used in a fuel cell of 3 kW-class electric generation.

In direct-injection (DI) gasoline engines, spray characteristics greatly affect engine combustion. For the rapid development of new gasoline direct-injectors, it is necessary to predict the spray characteristics accurately by numerical analysis based on the injector nozzle geometry. In this study, two-phase flow inside slit nozzle injectors is calculated using the volume of fluid method in a three-dimensional CFD. The calculation results are directly applied to the boundary conditions of spray calculations, of which the submodels are recently developed to predict spray formation process in direct injection gasoline engines. The calculation results are compared with the experiments. Good agreements are obtained for typical spray characteristics such as spray shape, penetration and Sauter mean diameter at both low and high ambient pressures. Two slit nozzle injectors of which the slit thickness is different are compared.

The cause of the exhaust smoke and its reduction methods in a small DI Diesel engine with a small-orifice-diameter nozzle and common rail F.I.E. were investigated under high-speed and high-load condition, using both in-cylinder observations and Three-dimensional numerical analyses. The following points were clarified during this study. At these conditions, fuel sprays are easily pushed away by a strong swirl, and immediately flow out to the squish area by a strong reverse squish. Therefore, the air in the cavity is not effectively used. Suppressing the airflow in a piston cavity, using such ideas as enlarging the piston cavity diameter or reducing the port swirl ratio, decreases the excessive outflow of the fuel-air mixture into the squish area, and allows the full use of air in the whole cavity. Hence, exhaust smoke is reduced.

A description is made of new control methods to improve response of wheel slip regulation. These methods enabled a new Traction Control (TRC) system based on throttle control rather than brake pressure to be developed. Major points are as follows: (1) Use of fuel injection cut-off to minimize delay (2) Additional adaptive throttle control logic By these means, a response nearly equal to that with brake pressure control is achieved at lower cost and with a considerable weight saving. Furthermore, the system, by suppressing noise and vibration, enhances the driver's control ability.

EXPERIMENTAL ANALYSIS for the increase of the radiator cooling air has been performed with special attention to the utilization of air pressure in high-speed running conditions. Measurements of pressure distributions at the radiator cooling air intake showed that the prevention of the occurrence of separations around the bumper is the efficient method to increase the cooling air. Furthermore, the optimum configuration for the radiator cooling air discharge has also been experimentally studied using a simplified model which simulates the under part of the engine compartment. These improvements made the vehicle radiator cooling air volume increase 14% under high-speed running conditions.

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.