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We have developed a method by which the oil flow rate can be measured by using a hot-wire sensor that could be installed in the passages of actual engine lubricant oil. This measuring method proves to have a ±5% accuracy and a 40kHz response that enables ‘real time’ function. Thus, observation of (1) the effect of bearing clearance, and (2) the fluctuating mechanism of the oil flow per 1 degree crank angle from the point of engine start-up to 6000r/min and full load can be achieved, and the timing and quantity of intermittent oil-jet from the oil hole in connecting rod were ascertained.

Maximum fuel injection pressures for GDI engines is expected to increase due to positive effects on emissions and engine-efficiency. Current GDI injectors have maximum operating pressures of 35 MPa, but higher injection pressures have yielded promising reductions in particle number (PN) and improved combustion stability. However, the mechanisms responsible for these effects are poorly understood, and there have been few studies on fuel sprays formed at high injection pressures. This paper summarizes experimental studies on the properties of sprays formed at high injection pressures. The results of these experiments can be used as inputs for CFD simulations and studies on combustion behavior, emissions formation, and combustion system design. The experiments were conducted using an injection rate meter and optical methods in a constant volume spray chamber. Injection rate measurements were performed to determine the injectors’ flow characteristics.

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.

Oil film thickness is one of the most important issues for optimization of bearing design. A technique has been developed to measure oil film thickness by noting the change in capacitance between the shaft and a thin-film electrode of several micrometers thickness formed on the surface of a bearing. The authors applied this technique to the main journals of an automobile engine and measured the oil film thickness up to maximum speed and full load. The oil film thickness became thinner with increased engine load, and then turned thicker with increased engine speed.

We developed a technique to measure oil film pressure distribution in engine main bearings using thin-film pressure sensors. The sensor is 7μm in thickness, and is processed on the surface of an aluminum alloy bearing. In order to increase the durability of the sensor, a layer of MoS2 and polyamide-imide was coated on thin-film sensors. This technique was applied to a 1.4L common-rail diesel engine operated at a maximum speed of 4,500r/min with a 100Nm full load, and the oil film pressure was monitored while the engine was operating. The measured pressure was compared with calculations based on hydrodynamic lubrication (HL) theory.

Thermal load caused by engine combustion is one of the important issues for the engines such as high-boosted downsized engines and engines with high compression ratio. In particular, it is necessary to maintain the reliability and durability of exhaust valves which are subject to the biggest thermal impact. For this reason, sodium filled hollow valves are utilized in preference to solid valves in order to decrease the exhaust valve temperature. The most common method for detecting the valve temperature is to estimate the temperature by measuring hardness on valve surface (Hardness test). However, the hardness test is only applicable to the condition up to 800°C. Therefore, this paper presents new techniques for measuring the temperature for sodium-filled valve using infrared thermography and thermocouple as an alternative hardness test. The authors also examined the valve temperatures at a variety of engine speeds and cooling of the sodium-filled valve during engine operation.

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.

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.

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.

Recently, there is a need for new applications of pressure sensor, such as direct fuel injection systems for protecting the environment, or power assisted brake systems for improved driving safety. For these widening areas of application, pressure sensors with higher accuracy, a wider pressure-sensing range, and integration of sensor chip functions are required. This paper discusses our development of automotive semiconductor pressure sensors.

In order to evaluate the toughness of automotive ECU's to electrostatic discharge, a conventional method where electrostatic discharge pulse is applied to connector parts on a printed circuit board is commonly used. But quantitative re-designing principles to improve the static electricity tolerance have not been made clear that completely utilizes the test data shown below till now, because propagation mechanism of static electricity on a circuit board is not clear. This paper describes the ESD current measurement technique which detects the near magnetic field generated by ESD currents. We developed to measure the ESD currents using the new loop antenna on a circuit board. The ESD current, was generated with the static electricity applied to a model circuit pattern in conformity with IEC and ISO standard and measured using the antenna. Also it was able to visualize how static electricity energy would propagate through the circuit board.

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).

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 required fuel spray characteristics, controlled fuel pressure, and injector installation configurations in gasoline direct injection differ among manufacturers. As a result, there are currently a variety of injector types and configurations being proposed by many different component manufacturers. This paper proposes a new injector design that both enables high fuel pressure operation by utilizing a highly efficient electromagnetic valve using a composite magnetic material for the injector actuator, and increases manufacturing productivity while also meeting the requirements of each engine manufacturer by simplifying the construction of the injector.

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 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 the field of automotive gasoline engines, new products aiming at greater fuel economy and cleaner exhaust gases are under development with the aim of preventing environmental destruction. Severe ignition environments such as lean combustion, stronger charge motion, and large quantities of EGR require ever greater combustion stability. In an effort to meet these requirements, an iridium plug has been developed that achieves high ignitability and long service life through reduction of its diameter, using a highly wear-resistant iridium alloy as the center electrode.(1)(2) Recently, direct injection engines have attracted attention. In stratified combustion, a feature of the direct injection engine, the introduction of rich air-fuel mixtures in the vicinity of the plug ignition region tends to cause carbon fouling. This necessitates plug carbon fouling resistance.

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.

The development of new systems to reduce exhaust gases is being investigated in response to OBD-II regulations and regulations all over the world relating to the introduction of low exhaust gas vehicles (LEV, ULEV, STEP3, STEP4). We have developed a highly responsive thermistor type catalyst temperature sensor that is very accurate, highly heat resistant, has a wide detection range, and that can be used in exhaust gas cleansing systems. The key technologies used in this new catalyst temperature sensor are: 1 Wide detection range: The thermistor is of a network construction that comprises a semi-conductor with a new Y-Cr-Mn perovskite crystal structure and an insulator. The temperature range can be set by changing the proportions of semi-conductor and insulator.

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.