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In response to the growing demand for fuel economy, we are developing a high-efficient variable displacement pump for hydraulic power steering systems. In order to develop a quiet variable displacement pump which generates lower noise for better vehicle interior sound quality, we have been developing a simulation tool which includes hydraulic analysis, vibration analysis, and vehicle interior noise analysis which combines simulation outputs and measured noise transfer functions of the targeted vehicle. This paper provides both validation results of the simulation tool and application examples to design improvement to conclude the effectiveness of the simulation tool developed.

We have achieved injection quantity range enhancement by using the current waveform control technique for direct injection (DI) gasoline injectors. In this study, we developed an injection quantity simulator to find out the mechanism of non-linear characteristics. We clarified the non-linear production mechanism by using the simulator. This simulator is a one-dimensional simulator that incorporates calculation results from both unsteady electromagnetic field analysis and hydraulic flow analysis into the motion equation of this simulation code. We investigated the relation between armature and the injection quantity by using the simulator. As a result, we clarified that the non-linearity was produced by the bounce of the armature in the opening action. Thus, we found that it is effective to reduce the armature bounce to improve the linearity of the injection quantity characteristics.

This paper presents a new substrate for Lean NOx Traps (LNT) which enables high NOx conversion efficiency, even after long-term aging, when using alkali metals as the NOx adsorber. When a conventional metal honeycomb is used as the LNT substrate, the chromium in the metal substrate migrates into the washcoat and reacts with the alkali metals after thermal aging. In order to help prevent this migration, we have developed a new substrate where a fine -alumina barrier is precipitated to the surface of the metal substrate. The new substrate is highly capable of preventing migration of chromium into the washcoat and greatly enhances the NOx conversion. The durability of the new substrate and emission test using a test vehicle are also examined.

Hydrogen produced from regenerative sources has the potential to be a sustainable substitute for fossil fuels. A hydrogen internal combustion engine has good combustion characteristics, such as higher flame propagation velocity, shorter quenching distance, and higher thermal conductivity compared with hydrocarbon fuel. However, storing hydrogen is problematic since the energy density is low. Hydrogen can be chemically stored as a hydrocarbon fuel. In particular, an organic hydride can easily generate hydrogen through use of a catalyst. Additionally, it has an advantage in hydrogen transportation due to its liquid form at room temperature and pressure. We examined the application of an organic hydride in a spark ignition (SI) engine. We used methylcyclohexane (MCH) as an organic hydride from which hydrogen and toluene (TOL) can be reformed. First, the theoretical thermal efficiency was examined when hydrogen and TOL were supplied to an SI engine.

Every fuel injection system for DI gasoline engines has a DC-DC converter to provide high, stabile voltage for opening the injector valve more quickly. A current control circuit for holding the valve open is also needed, as well as a large-capacity capacitor for pilot injection. Since these components occupy considerable space, an injector drive unit separate from the ECU must be used. Thus, there has been a need for a fuel injection system that can inject a small volume of fuel without requiring high voltage. To meet that need, we have developed a dual coil injector and an opening coil current control system. An investigation was also made of all the factors related to the dynamic range of the injector, including static flow rate, fuel pressure, battery voltage and harness resistance. Both efforts have led to the adoption of a battery voltage-driven fuel injector.

To detect an air-fuel ratio in wide range is very important to control the automotive engines with low fuel consumption and low exhaust emissions. Although the application of zirconia electrolyte for this purpose has been proposed by the authors several years ago, there remained several problems due to the contamination of gas diffusion apertures which are exposed to the exhaust gas environment. Here the behavior of ions transported in zirconia electrolyte have been analyzed to optimize the structure and characteristics, and to guarantee the long life operation of sensor. Gas contents and their reactions in combustion process under the wide range air-fuel ratio have been analyzed, and these results were reflected to the analysis of ion transportation in zirconia electrolyte. Experimental results supported the analytical results, and they showed the possibilities of long life operation of zirconia air-fuel ratio sensor utilizing ion transportation phenomena.

Plastic optical fiber has been widely used in the field of short distance optical transmission. However heat resistance of commercial plastic fiber is so low that its applications are limited. Then, a plastic fiber of thermosetting acrylate resin core has been developed. This fiber shows 80%/m retention of light transmittance at 1m after 1,000 hours at 150°C. It resists heat deformation and withstands up to 200 °C for a short time period. Tests show this fiber has desirable mechanical characteristics, along with good environmental resistance. In addition, a fiber which has a silicon resin as a core material was developed which has even better heat resistance.

We developed the numerical simulation tool by using OpenFOAM® and in-house simulation codes for Gasoline Direct Injection (GDI) engine in order to carry out the precise investigation of the throughout process from the internal nozzle flow to the fuel/air mixture in engines. For the piston/valve motions, a mapping approach is employed and implemented in this study. In the meantime, the spray atomization including the liquid-columnbreakup region and the secondary-breakup region are simulated by combining the different numerical approaches applied to each region. By connecting the result of liquid-column-breakup simulation to the secondary-breakup simulation, the regions which have different physical phenomena with different length scales are seamlessly jointed; i.e., the velocity and position of droplets predicted by the liquid-column-breakup simulation is used in the secondary breakup simulation so that the initial velocity and position of droplets are transferred.

We have developed an excitation source identification system that can distinguish excitation sources on a sub-assembly level (around 30mm) for vehicle components by combining a measurement and a timing analysis. Therefore, noise and vibration problems can be solved at an early stage of development and the development period can be shortened. This system is composed of measurement, control, modeling, and excitation source identification parts. The measurement and the excitation source identification parts are the main topics of this paper. In the measurement part, multiple physical quantities can be measured in multi-channel (noise and vibration: 48ch, general purpose: 64ch), and these time data can be analyzed by using a high-resolution signal analysis (Instantaneous Frequency Analysis (IFA)) that we developed.

The problem of high fatal accident rates due to drunk driving persists, and must be reduced. This paper reports on a prototype system mounted on a car mock-up and a prototype portable system that enables the checking of the drivers’ sobriety using a breath-alcohol sensor. The sensor unit consists of a water-vapor-sensor and three semiconductor gas sensors for ethanol, acetaldehyde, and hydrogen. One of the systems’ features is that they can detect water vapor from human-exhaled breath to prevent false detection with fake gases. Each gas concentration was calculated by applying an algorithm based on a differential evolution method. To quickly detect the water vapor in exhaled breath, we applied an AC voltage between the two electrodes of the breath-water-vapor sensor and used our alcohol-detection algorithm. The ethanol level was automatically calculated from the three gas sensors as soon as the water vapor was detected.

We have developed a model-based control for the air intake system in a variable valve engine, employing total engine simulation, the response surface method and multi-objective optimization scheme. In our technique, we performed the simulation model tuning and validation, followed by the creation of a dataset for the polynomial regression analysis of the charging efficiency. A D-optimal design, robust least squares method, and likelihood-ratio test were demonstrated to yield a robust and accurate control model. Coupling the total engine simulator with a genetic algorithm, model based calibration for optimal valve timing stored in lookup table was carried out under multiple objectives and restrictions. The reliability of the implementation control model, which considers the effect of gas dynamics in the intake system, was confirmed using a model-in-the-loop simulation.

Predicting the vibration of a motor gearbox assembly driven by a PWM inverter in the early stages of development is demanding because the assembly is one of the dominant noise sources of electric vehicles (EVs). In this paper, we propose a simulation model that can predict the transient vibration excited by gear meshing, reaction force from the mount, and electromagnetic forces including the carrier frequency component of the inverter up to 10 kHz. By utilizing the techniques of structural model reduction and state space modeling, the proposed model can predict the vibration of assembly in the operating condition with a system level EV simulator. A verification test was conducted to compare the simulation results with the running test results of the EV.

We investigated the size of fuel spray droplets from nozzles for direct injection gasoline (DIG) engines. Our findings showed that the droplet size can be predicted by referencing the geometry of the nozzle. In a DIG engine, which is used as part of a system to reduce fuel consumption, the injector nozzle causes the fuel to spray directly into the combustion chamber. It is important that this fuel spray avoid adhesion to the chamber wall, so multi-hole injection nozzles are used to obtain spray shape adaptability. It is also important that spray droplets be finely atomized to achieve fast vaporization. We have developed a method to predict the atomization level of nozzles for fine atomization nozzle design. The multi-hole nozzle used in a typical DIG injector has a thin fuel passage upstream of the orifice hole. This thin passage affects the droplet size, and predicting the droplet size is quite difficult if using only the orifice diameter.

The purpose of this study is to develop model-based methodologies which employ thermo-fluid dynamic engine simulation and multiple-objective optimization schemes for engine control and calibration, and to validate the reliability of the method using a dynamometer test. In our technique, creating a total engine system model begins by first entirely capturing the characteristics of the components affecting the engine system's behavior, then using experimental data to strictly adjust the tuning parameters in physical models. Engine outputs over the full range of engine operation conditions as determined by design of experiment (DOE) are simulated, followed by fitting the provided dataset using a nonlinear response surface model (RSM) to express the causal relationship among engine operational parameters, environmental factors and engine output. The RSM is applied to an L-jetronic® air-intake system control logic for a turbocharged engine.

Most automatic transmissions are controlled in compliance with a predetermined program. Transient control during gear shift is also carried out according to a predetermined process. In this method a lot of labor is required to tune data tables. So we developed a tuning free system by feedback control using torque estimation technology and the experimental result is reported. Torque fluctuation during shift is detected and fed back to compare the torque reference, which is generated from the estimated torque itself. The engine torque is decreased by means of retarding the ignition spark advance, according to the comparison deviation. As a consequence of the feedback, the transient torque control is carried out without any tuning trouble, and better than usual torque fluctuation is obtained.

A new engine drivetrain control system is described which can provide a higher gear ratio and leaner burning mixture and thus reduce the fuel consumption of spark ignition engines. Simulations were performed to obtain reduced torque fluctuation during changes in the air - fuel ratio and gear ratio, without increasing nitrogen oxide emissions, and with minimum throttle valve control. The results show that the new system does not require the frequent actuation of throttle valves because it uses direct fuel injection, which increases the air - fuel ratio of the lean burning limit. It also achieves a faster response in controlling the air mass in the cylinders. This results in the minimum excursion in the air - fuel ratio which in turn, reduces nitrogen oxide emissions.

We developed a high-pressure fuel pump for a direct injection gasoline engine and used a hydraulic simulator to design it. A single plunger design is the major trend for high-pressure fuel pumps because of its simple structure and small size. However, the single plunger causes large pressure pulsation and an unstable flow rate, especially at high engine speed. Therefore, a fuel-pipe layout that inhibits the pressure pulsation and a flow-rate control that stabilizes the flow are the most important challenges in pump design. Our newly developed hydraulic simulator can evaluate the dynamic characteristics of a total fuel supply system, which consists of pump, pipe, injector, and control logic. Using this simulator, we have improved fuel flow by optimizing the outlet check valve lift and the cam profile, and we reduced pressure pulsation by optimizing the layout of fuel pipes. Our simulation results agreed well with our experimental results.

Magnetic Phase Shifter is the controlling element to make integral action, excellent in anti-noise performance and makes high stable and reliable controlling device. (1)* We have developed a new compact thyristor chopper equipment controlled by Magnetic Phase Shifter. This equipment has simple controlling circuit and many functions such as wide range duty factor control, adjustable plugging brake, speed up by field weakening, anti-rollback control and so on.

Mixture formation technology for gasoline engine multipoint fuel injection systems has been investigated. The fuel injector's spray, the volatility of droplets floating in the air flow, the movement of droplets around the intake valve's upper surface, the volatility of droplets on heated surfaces, and the process of atomizing droplets in the intake valve air flow was analyzed. Droplet diameters and spray patterns for good mixture formation without liquid film in cylinders have been clarified. When sequential injection is used for better responsiveness in fuel injection systems, engine performance may be reduced through increased HC emissions in some conditions. Reducing the diameter of spray droplets and preventing fuel from concentrating in the intake valve promotes vaporization, reduces fuel concentration on cylinder walls, and prevents reductions in engine performance.

A multiplexed transmission system utilizing newly developed optical polymer has been proposed. The system is composed of a star-shaped optical network, in which optical signals can be transmitted bi-directionally through a fiber and optical branches between the central and local controllers. The new polymer optical fiber has been developed and adopted for this system, and it was designed to be durable to the high temperature in automotive engine rooms. The high temperature resistibility of the fiber has been achieved with utilization of a thermo-setting resin for the core materials. The optical loss characteristics of the fiber is as low as 0.50 dB/m at 660 nm wavelength.