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Previous studies have investigated the impacts of biofuel usage on the performance, drivability and durability of modern diesel engines and exhaust after-treatment systems including test work with different types, concentrations and mixtures of bio fuel components. During this earlier work vehicle fuel filter blocking issues were encountered during a field trial using various types of EN 14214 compliant Fatty Acid Methyl Ester (FAME) blended into EN 590 diesel. This paper summarises a subsequent literature review that was carried out looking into potential causes of this filter blocking and further work that was then carried out to expand on the findings. From this, a laboratory study was carried out to assess the increase in fuel filter blocking tendency (FBT) when various FAMEs from mixed sources were blended into EN 590 diesel at different concentrations, including levels above those currently allowed in the European market.

From the viewpoint of the global warming restraint, reduction of exhaust emissions from diesel engine is urgent demand. However, it needs further development in combustion control besides after treatment system. Larger amount of EGR (Exhaust Gas Recirculation) is effective to reduce NOx emission. On the other hand, in-cylinder physical conditions greatly influence on self-ignition and combustion process, especially low O2 fraction charged gas owing to excessive EGR causes misfire. A drastic solution for this problem, fuel injection timing should be optimally manipulated based on predicted ignition delay period before actual injection. For this purpose, Toyota has developed a model based diesel combustion control concept to avoid the misfire and to keep low emission combustion includes in transient condition.

A computational and experimental study has been carried out to assess the high load efficiency and emissions potential of a combustion system designed to operate on low octane gasoline (or naphtha). The “naphtha engine” concept utilizes spark ignition at low load, HCCI at intermediate load, and compression ignition at high load; this paper focuses on high load (compression ignition) operation. Experiments were carried out in a single cylinder diesel engine with compression ratio of 16 and a common rail injector/fuel delivery system. Three fuels were examined: a light naphtha (RON∼59, CN∼34), heavy naphtha (RON∼66, CN∼31), and heavy naphtha additized with cetane improver (CN∼40). With single fuel injection near top dead center (TDC) (diesel-like combustion), excessive combustion noise is generated as the load increases. This noise limits the maximum power, in agreement with the CFD predictions. The noise-limited maximum power increases somewhat with the use of single pilot injection.

The purpose of this study is to analyze the piston skirt friction reduction effect of a diamond-like carbon (DLC)-coated wrist pin. The floating liner method and elasto-hydrodynamic lubrication (EHL) simulation were used to analyze piston skirt friction. The experimental results showed that a DLC-coated wrist pin reduced cylinder liner friction, and that this reduction was particularly large at low engine speeds and large pin offset conditions. Friction was particularly reduced at around the top and bottom dead center positions (TDC and BDC). EHL simulation confirmed that a DLC-coated wrist pin affects the piston motion and reduces the contact pressure between the piston skirt and cylinder liner.

Behavior of sprays formed by slit nozzle as well as swirl nozzles with the spray cone angle in the range of 40° ∼110 ° were studied in a constant volume N2 gas chamber. The fuels used are iso-pentane, n-heptane, benzene and gasoline. The ambient pressure and temperature were raised up to 1.0 MPa and 465 K, respectively. The injection pressure was mainly set at 8 MPa. Spray penetrates at an almost constant speed for a while after injection start and begins to decelerate at a certain point. This point was judged as breakup point, based on a momentum theory on spray motion, the observation of spray inside and the analysis of the spray front reacceleration which occurs under highly volatile condition.

The effects of biodiesel oxidation stability on diesel fuel injection equipment (FIE) behavior were investigated using newly developed test rig and methodology. On the test rig, biodiesel blend fuels were circulated through a fuel tank and a common rail injection system. Fuel injected from typical diesel injectors was returned into the fuel tank to enhance the speed of fuel degradation. The results showed that injector deposits could be reproduced on a test rig. It was observed that injector body temperature increase accelerates the degradation of fuel and therefore gives earlier FIE failure. Fuel renewal could partially restore the injection quantity after complete failure at low injection pressure, thus showing a potential cleaning effect on injector deposits when refueling a car.

To meet future stringent emission regulations such as Euro6, the design and control of diesel exhaust after-treatment systems will become more complex in order to ensure their optimum operation over time. Moreover, because of the strong pressure for CO₂ emissions reduction, the average exhaust temperature is expected to decrease, posing significant challenges on exhaust after-treatment. Diesel Oxidation Catalysts (DOCs) are already widely used to reduce CO and hydrocarbons (HC) from diesel engine emissions. In addition, DOC is also used to control the NO₂/NOx ratio and to generate the exothermic reactions necessary for the thermal regeneration of Diesel Particulate Filter (DPF) and NOx Storage and Reduction catalysts (NSR). The expected temperature decrease of diesel exhaust will adversely affect the CO and unburned hydrocarbons (UHC) conversion efficiency of the catalysts. Therefore, the development cost for the design and control of new DOCs is increasing.

Despite the fact that methanol is toxic to human health and causes serious damage to automobile engines and fuel system components, methanol-containing gasoline is becoming popular in some areas. Methanol demonstrates similar chemical properties to ethanol (which is already established as an additive to gasoline), so that it is difficult to identify methanol-containing gasoline without performing proper chemical analysis. In this study, we report a low-cost, portable, and easy-to-operate sensor that selectively changes color in response to methanol contained in gasoline. The colorimetric sensor will be useful for automobile users to avoid methanol-containing gasoline upon refueling.

Toyota has been continuing to study economy and general-purpose starting technologies for smaller displacement engines, since market introduction of the 42-14V MHV in 2001. This study shows one of the strategies for nearly silent and fast starting for economy size cars, which have smaller displacement engines by utilizing a small MG (motor generator) at 12 Volts. The most significant issue for realizing advanced starting features (silent, fast and smooth) is the cost. Power electric components, especially, have a large cost disadvantage, which is generally proposed to the controlling power. So efforts were made to reduce the electrical power requirements. Also methods for minimizing additional components and utilizing conventionally existing components (e.g. sensors) are discussed in this paper. Another characteristic is that smaller displacement engines (e.g. I4, I3) have larger cranking torque difference characteristics than larger engines (e.g. I6, I8).

This research investigates the influences of the injection timing, injection pressure, and compression ratio on the combustion and exhaust emissions in a single cylinder 1.0 L DI diesel engine operating with ultra-high EGR. Longer ignition delays due to either advancing or retarding the injection timing reduced the smoke emissions, but advancing the injection timing has the advantages of maintaining the thermal efficiency and preventing misfiring. Smokeless combustion is realized with an intake oxygen content of only 9-10% regardless of the injection pressure. Reduction in the compression ratio is effective to reduce the in-cylinder temperature and increase the ignition delay as well as to expand the smokeless combustion range in terms of EGR and IMEP. However, the thermal efficiency deteriorates with excessively low compression ratios.

Generally Hybrid Electrical Vehicles (HEV's) tend to have difficulty with regard to evaporative emissions because they have less capability of purging canisters compared with that of conventional systems. Toyota has developed a new fuel system that can address this difficulty and enables outstanding performance for the new-generation HEV. The fuel system, called the “Fuel Vapor-containment System (FVS)”, consists of newly developed or redesigned components, such as a high strength fuel tank, a Fuel Vapor-containment Valve (FVV), refueling canister and a purge buffer as well as newly defined controls of the components for the vehicle. The fuel tank is sealed while a vehicle is parked and fuel vapor does not flow into the canister by control of the FVV, except during refueling events. Therefore, HEV's do not have to ensure as much as purge capacity to achieve the necessary lower evaporative requirements.

Due to new CO2 regulations and increasing demand for improved fuel economy, reducing aerodynamic drag has become more critical. Aerodynamic drag at the rear of the vehicle accounts for approximately 40% of overall aerodynamic drag due to low base pressure in the wake region. Many studies have focused on the wake region structure and shown that drag reduction modifications such as boattailing the rear end and sharpening the rear edges of the vehicle are effective. Despite optimization using such modifications, recent improvements in the aerodynamic drag coefficient (Cd) seem to have plateaued. One reason for this is the fact that vehicle design is oriented toward style and practicality. Hence, maintaining flexibility of design is crucial to the development of further drag reduction modifications. The purpose of this study was to devise a modification to reduce rear drag without imposing additional design restrictions on the upper body.

In order to clarify the combustion behavior in the ultra high engine speed range, a new technique has been developed. This technique is composed of ionization current detection and flame observation, and is highly heat-resistant, vibration-resistant, and has a quick response. From analyzing the flame front propagation in the high-speed research engine, it was found that the flame propagated throughout the entire cylinder over almost the same crank angle period irrespective of engine speed introduction.

We expect to reduce exhaust gas emissions further and improve fuel consumption, by developing a new brake system (called brake-by-wire system) to control the friction brake force and the regenerative brake force of the two motors, one each at front and rear axle. Within this new system we developed the new technology listed below. 1 To compensate the changes of the regenerative brake force of front and rear motors, the friction brake force is controlled by adjusting the wheel cylinder hydraulic pressures. 2 The pressure of each wheel cylinder is controlled by linear solenoid valves. So the hydraulic pressure of wheel cylinders is controlled individually and smoothly. This brake system also operates ABS, VSC, TRC functions. The vehicle stability performance is improved by controlling the braking and driving torque of two motors and also controlling the friction brake torque cooperatively.

Port fuel injection (PFI) injector and direct fuel injection (DI) injector clogging from deposits caused by poor fuel quality, is a concern in emerging countries. Then DI injector deposits are sometimes cleaned by injector cleaners in such situation. However deposit cleaners for PFI injectors have not been developed, because of the lack of research of PFI injector deposits. Through chemical analysis, this study showed them to be water-soluble deposits. Subsequently success was achieved in developing a new gasoline injector cleaner applicable to injector deposits in both types of injectors, through optimization of a surface active agent.

To improve the thermal efficiency of an internal combustion engine, the application of ceramics to heat loss reduction in the cylinders has been studied [1-2]. The approach taken has focused on the low heat conductivity and high heat resistance of the ceramic. However, since the heat capacity of the ceramic is so large, there is a problem in that the wall temperature increases during the combustion cycle. This leads to a decrease in the charging efficiency, as well as knocking in gasoline engines. To overcome these problems, the application of thermal insulation without raising the gas temperature during the intake stroke has been proposed [3-4]. As a means of achieving this, we developed a "temperature swing heat insulation coating" [5, 6, 7, 8, 9]. This reduces the heat flux from the combustion chamber into the cooling water by making the wall temperature follow the gas temperature as much as possible during the expansion and exhaust strokes.

Awareness of environmental protection with respect to the particulate number (PN) in the exhaust emissions of gasoline direct injection (GDI) engine vehicles has increased. In order to decrease the emission of particulate matter (PM), suppressing emissions by improving engine combustion, and/or filtering PM with a gasoline particulate filter (GPF) is effective. This paper describes the improvement of the coated GPF to reduce pressure drop while securing three-way performance and PN filtration efficiency. It was necessary to load a certain amount of washcoat on the GPF to add the three-way function, but this led to an increase in pressure drop that affected engine power. The pressure drop was influenced by the gas permeation properties of the filter wall.

An unique diesel engine electronic control system has been developed, which contains two distinctive features. Firstly, the delivery type fuel injection pump has an electro-magnetic valve to control the quantity of fuel injected. This valve is then acutuated to ensure that the timing of the high pressure fuel flow out stops the fuel injection. In the previous diesel electronic control system, the fuel quantity control was effected via the position control of a mechanical spill ring. Since timing control is more suitable than position control for handling by a microcomputer, the electro-magnetic valve is able to control the quantity of fuel injected more precisely, whilst consisting of a simpler structure. Secondly, an optical combustion timing sensor is able to detect initial combustion timing by sensing the light of the combustion flame in the combustion chamber. Using the signal from the sensor, the microcomputer then exerts a compensating control over the fuel injection timing.

In order to optimize air-fuel mixture formation in a small DI diesel engine, studies were conducted into the effects of combustion chamber shape and fuel spray impingement. Based on the findings of these studies, the shape of the combustion chamber was modified to induce complex air motion with high turbulence and fuel injection was carefully controlled to achieve optimum impingement intensity. As a result, the mixture formation process was greatly improved with a consequent gain in terms of engine performance. To clarify the reasons for this improvement in combustion, a three-dimensional calculation of the in-cylinder air motion was made. The behaviour of the spray and flame was observed using an endoscope. The new combustion system, named TOYOTA Reflex Burn system (TRB) thus developed has been adopted in production engines since August 1988.

In anticipation of the increased needs to further reduce exhaust gas emissions and improve fuel consumption, a new brake-by-wire system called an “Electronically Controlled Brake” system (hereafter referred to as “ECB”) has been developed. With this brake system, which is able to smoothly control the hydraulic pressure that is applied to each of the four wheel cylinders on an individual basis, functional enhancements can be added by appropriately modifying its software. This paper discusses the necessity of the ECB, the system configuration, and the results of its application on hybrid vehicles.