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The backward flow of the hot burned gas surrounding a diesel flame was found to be one of the factors dominating the set-off length (also called the lift-off length), that is, the distance from a nozzle exit into which a diffusion flame cannot intrude. In the combustion chamber of an actual diesel engine, the entrainment of the surrounding gas into a spray jet from a multi-hole nozzle is restricted by the walls and adjacent spray jets, which induces the backward flow of the surrounding gas. A new momentum theory to calculate the backward flow velocity was established by extending Wakuri's momentum theory. Shadowgraph imaging in an optical engine successfully visualized the backward flow of the hot burned gas.

The need to improve fuel consumption by saving the weights of automobile parts is growing from the viewpoint of global warming mitigation. In the case of a throttle body for controlling the air flow volume into an engine, it is important to achieve a high dimensional accuracy of the valve-bore gap in the state of closed valve. In fact, most throttle bodies are made of precision-machined metal. Therefore, resin throttle bodies are drawing attention as a lightweight alternate. However, in comparison with metal throttle bodies, resin throttle bodies have two potential disadvantages that should be solved prior to productization. The first one is greater air leakage in the state of closed valve, and the second one is smaller heat conduction for unfreezing the valve in a frigid climate. We have developed an electronic resin throttle body that has overcome the above-mentioned disadvantages.

The hole diameter of injection nozzles in diesel engines has become smaller and the nozzle coking could potentially cause injection characteristics and emissions to deteriorate. In this research, engine tests with zinc-added fuels, deposit analyses, laboratory tests and numerical calculations were carried out to clarify the deposit formation mechanisms. In the initial phase of deposit formation, lower zinc carboxylate formed close to the nozzle hole outlet by reactions between zinc in the fuel and lower carboxylic acid in the combustion gas. In the subsequent growth phase, the main component changed to zinc carbonate close to nozzle hole inlet by reactions with CO₂ in the combustion gas. Metal components and combustion gases are essential elements in the composition of these deposits. One way of removing these deposits is to utilize cavitations inside the nozzle holes.

In recent years, the use of acrylic rubber has grown because of improved low temperature performance and heat resistance. Acrylicrubber is now being adopted as a replacementof NBR because it has good oil and heat resistance. One special feature inherent toacrylic rubber is that if it is in contact withmetal, upon heating, it will adhere to the metal. This adhesion would not be a problem with a fixed O-ring; however, in the case of an oilfilter (O/F) gasket which is regularly changed,the rubber which remains due to adhesion couldbe problematic for sealing. In the past, this problem was overcome by utilizing a coating, such as silicone, on the rubber surface, although this adds another step to the rubber process. Therefore, we developed a new method to prevent the adhesion of acrylic rubber by analyzing the mechanism by which the acrylic rubber adheres to a metal surface.

In this paper, we will introduce a stereo vision system developed as a sensor for a vehicle's front monitor. This system consists of three parts; namely, a stereo camera that collects video images of the forward view of the vehicle, a stereo ECU that processes its output image, and a near-infrared floodlight for illuminating the front at night. We were able to develop an obstacle detection function for the Pre-Crash Safety System and also a traffic lane detection function for a Lane-Keeping Assist System. Especially in regard to the obstacle detection function, we were able to achieve real-time processing of the disparity image calculations that had formerly required long processing times by using two types of recently developed LSIs.

From the view of suppressing the global warming and environmental pollution, responding to the regulation of fuel consumption and exhaust gases along with lengthening the maintenance interval, are becoming more demanded. The development of a high-performance, long-life spark plug has become essential in response to these demands. While improved performance (high ignitability and low required voltage), the discharge part of the spark plug needs to be reduced in size. But, in the past this has been difficult because of the limitations of platinum alloys in terms of wear. Therefore, it has been quite difficult to achieve both smaller discharge parts and longer life. To dramatically improve wear resistance, we researched materials that are both resistant to oxidation and have a high melting point. This research resulted in our development of a new iridium alloy (Iridium-10wt%Rhodium).

This paper presents the oil circulation behavior in a CO2 climate control system operating at low evaporating temperature down to -32°C. The increase of oil circulation ratio (OCR) from 0 to 6 wt.% during steady state conditions degrades the coefficient of performance and cooling capacity by 15% and 8%, respectively. The pressure drop across the heat exchangers increases, especially in the gas cooler. In low temperature CO2 systems some fluctuations of oil and refrigerant flow rates were observed during cyclic operations when the system did not equip the oil separator, but was observed only at high oil charge when the system did equip the oil separator. These instabilities lead to a periodic compressor performance fluctuation, which caused system performance degradations. Therefore, the use of an oil separator is recommended for the low temperature operation if an ordinary metering valve is adopted as an expansion device without any special control strategy.

In gasoline direct injection engines it is important to optimize fuel spray characteristics, which strongly affect stratified combustion process. Spray simulation is anticipated as a tool for optimizing nozzle design, but conventional simulation, which is based on experimental data and/or empirical laws regarding spray boundary condition at the nozzle exit, cannot predict the effect of various nozzle geometries on spray characteristics. In Japan, a fan spray injected from a slit type nozzle has recently been adopted for gasoline direct injection engines. This paper proposes a computational model for the fan spray. The structure of two-phase flow inside the nozzle is numerically analyzed using the volume of fluid (VOF) method in a three-dimensional CFD code based on the nozzle geometry. The results of these analyses are applied to classical linear instability theory to calculate fuel droplet mean diameter after primary breakup.

We have proposed First Order Analysis (FOA) as a method, which the engineering designers themselves can use easily in an initial design stage. In this paper, we focus on the crashworthiness, and present the method to predict the collapse behavior of the frame member. This method is divided into two parts. Those are (1) collapse analysis under loading conditions of combined axial force and bending moment to the cantilever, and (2) collapse analysis of structural member considering the previously obtained moment - rotation angle relationship using the beam element. In comparison with the results according to the detailed Finite Element Analysis (FEA) model, effectiveness and validity of this method are presented.

The automotive industry has increasingly been focusing its efforts on vehicle part weight reduction, with the aim of improving fuel efficiency as an environmental protection measure. As part of these efforts, the industry has actively been developing plastic pulleys to replace conventional steel pulleys. Of the various pulleys used in vehicles, the air conditioner (A/C) compressor pulley is exposed to the harshest working environment. We therefore investigated towards development of a plastic pulley for A/C compressor application. Required material properties were first identified on the basis of required product characteristic values. As a result, a phenolic resin material was developed that is superior in heat resistance one of the most important properties among those identified. Using the material, we succeeded in developing an A/C compressor plastic pulley, achieving approximately 50% weight reduction compared to conventional steel pulleys.

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 stratification feature of DI gasoline combustion was studied by using a constant volume combustion vessel. An index of stratification degree, defined as volumetric burning velocity, has been proposed based on the thermodynamic analysis of the indicated pressure data. The burning feature analysis using this stratification degree and the fuel vapor concentration measurement using He-Ne laser ray absorption method were carried out for the swirl nozzle spray with 90° cone angle and the slit nozzle spray with 60° fan angle. Ambient pressure and ambient temperature were changed from atmospheric condition to 0.5∼0.6 MPa and 465 K, respectively. Air Swirl with swirl ratio of 0∼1.0 were added for the 90° swirl nozzle spray. Single component fuels with different volatility and self-ignitability from each other were used besides gasoline fuel. The major findings are as follows. High ambient temperature improves stratification degree due to the enhanced fuel vaporization and vapor diffusion.

Recently CO₂ emission regulation has become more stringent and higher thermal efficiency of the internal combustion engine is required. Spray-guided gasoline direct injection engine has promising potential for lower fuel consumption. The purpose of this study is to clarify the air-fuel mixture formation requirements and to investigate the spray specification of multi-hole nozzle injector for spray-guided stratified combustion.

Quality control of gasoline constituents and its effect on the Intake Valve Deposits (IVD) has become a recent issue. In this paper, the effects of gasoline and oil quality on intake valve deposits were investigated using an Intake Valve Deposit Test Bench and a Sludge Simulator. The deposit formation from the gasoline maximized at an intake valve temperature of approximately 160 °C, and the deposits formed from the engine oil were maximum at approximately 250 °C. Therefore, the contribution of the gasoline or the engine oil appears to depend on the engine conditions. The gasoline which contains MTBE or ethanol with no detergent additive slightly increases the deposition amount. The gasoline with a superior detergent significantly decreases the deposition amount even when MTBE or ethanol is blended in the gasoline. Appropriate detergent fuel additive retards the oil deterioration.

The EHD lubrication model of connecting rod big end bearings is compared with experiments using an automotive diesel engine. The axial load and the bending moment near the middle of rod length were derived from strain measurements and compared with the theoretical results based on engine dynamics. Although oscillation appeared on bending moment at 5000 rpm, the theoretical load almost agreed with the experiment. The EHD lubrication theory and the experiments were compared by the histories of clearances and the journal center orbits in the bearing. The theoretical results agreed well with the experimental one. The deformation of the bearing appeared both in the theory and in the experiment at 3000 rpm or above; these results confirm the necessity of the EHD lubrication theory.

Temperature distributions on the surface of a connecting rod big end bearing were measured to understand the margin to the allowable limiting temperature. The results show that the temperature difference between the bearing surface and the feed oil is independent of the engine load but quadratically increased with the engine speed, and that the bearing surface temperature on the rod side is higher than those on the cap side, and that the high temperature regions appeared near the edges on the rod side of the bearing under high speed operations. The results were analyzed by the observation of rubbing traces on the bearing surface and the EHD lubrication theory.

Three-dimensional numerical analysis of fuel liquid and mixture behavior in a port-injection gasoline engine is assessed by comparing calculations with measurements. The fuel mass distributed in the intake port and cylinder is measured using an engine with hydraulic valve and gas sampling system. The experimental results show that about half of the fuel mass per injection enters the cylinder, and the rest stays in the port. The difference of the mass fraction of injected fuel directly entering the cylinder is small between the cases of single pulse injection and serial injection. Therefore, three-dimensional calculation presupposing single pulse injection has difficulty in predicting the in-cylinder mixture formation process, although it can analyze the amount of fuel wetting the port wall. The calculations are performed for a port-injection engine, and the differences of fuel behavior with respect to swirl control valve opening and wall temperature are discussed.

The recent progress of electronic control systems in vehicles is remarkable as evidenced by the development of electronic fuel injection systems,(EFI), automatic transmission control systems, and anti-lock brake systems,(ABS). The number of actuators for the systems has been increasing. Consequently, a need has been identified for a reduction in volume and number of the system actuators for control purposes. A composite magnetic material has been developed with the aim of miniaturizing magnetic solenoid valves for actuator applications. A composite magnetic material is such that both ferromagnetic and paramagnetic sections coexist within a single material, and can contribute to optimization of the magnetic circuit of a solenoid valve. This paper describes the development of a composite magnetic material, and its resultant characteristics.

This paper will focus on fuel flow analysis in nozzles, in particular, in the injection hole, a key component of Fuel Injection Equipment(FIE). Optimum controlled flow in the hole improves flow efficiency and atomization. To meet the emission regulations which will be introduced from the end of '90's to the 21st century, Diesel Engines require FIE to produce higher injection pressure which creates better atomization and higher utilization of air. But higher injection pressure results in increased pump driving torque, larger pump size and higher cost. We have studied the improvement in fuel flow characteristics of the nozzle, using an enlarged flow model and the theoretical analysis method. As a result, we have found that the cavitation, which occurs at the inlet of the hole, is affected by the configuration of the sac hole and injection hole. And, furthermore, the cavitation has a direct effect on the contraction and its recovery flow.

For improving DI diesel engine performance, such as lower nitrogen oxidant (NOx), particulate molecular (PM) emission and higher output, etc., atomization of the fuel spray plays an important role. In order to obtain better fuel atomization without increasing the fuel injection pressure, increasing the flow velocity at the injection nozzle spray holes is regarded as an effective way. Through experiments, enlarging the chamfer at the spray hole inlet proved to be the most effective and suitable method for establishing high flow velocity injection nozzles. We have compared the high flow velocity injection nozzles with conventional nozzles in terms of injection characteristics and fuel spray characteristics, and confirmed the improved fuel spray atomization with the high flow velocity injection nozzles. Finally the high flow velocity injection nozzles were tested on a medium duty class, natural aspirated DI diesel engine.