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In the automobile industries, weight reduction has been investigated to improve fuel efficiency together with reduction of CO2 emission. In such circumstance, it becomes necessity to make an electric power steering (EPS) more compact and lightweight. In this study, we aimed to have a smaller and lighter EPS gear size by focusing on an impact load caused at steering end. In order to increase the shock absorption energy without increase of stopper bush size, we propose new theory of impact energy absorption by not only spring function but also friction, and a new stopper bush was designed on the basis of the theory. The profile of the new stopper bush is cylinder form with wedge-shaped grooves, and when the new stopper bush is compressed by the end of rack and the gear housing at steering end, it enables to expand the external diameter and produce friction. In this study, we considered the durability in the proposed profile.

This paper will discuss the stress reduction of the worm wheel for an electric power steering (EPS) system. The research discussed in this paper focused on the worm wheel, the EPS component that determines the maximum diameter of the system. If the stress of the worm wheel could be reduced without increasing in size, it would be possible to reduce the size of the worm wheel and EPS system. In order to reduce the stress of the worm wheel, the conventional design method has extended the line-of-action toward outside of the worm wheel to increase the contact ratio of the gears and these method lead to an increase in the outer diameter. In order to address this issue, past research proposes the basic concept to extend line-of-action toward the inside of the worm wheel. And this new meshing theory was named MUB (Meshing Under Base-circle) theory. In this paper, characteristics of meshing of the gear formed by MUB theory are determined in more detail.

Exhaust heat recovery units that use a thermoelectric element generate electricity by creating a temperature difference in the thermoelectric element by heating one side and cooling the other side of the thermoelectric circuit (module). In this case, the general structure does not directly join the thermoelectric module with the heat sink, and instead presses the thermoelectric module against the heat sink using bolts or other means in order to prevent thermoelectric element damage due to the difference in linear expansion between the cooled and heated sides of the thermoelectric module. However, this poses the issues associated with a complex, heavy and expensive structure. Therefore, a new vacuum space structure was devised that houses the thermoelectric module in a vacuum chamber and presses the module against the heat sink using atmospheric pressure.

In the early stages of aerodynamic development of commercial vehicles, the aerodynamic concept is balanced with the design concept using CFD. Since this development determines the aerodynamic potential of the vehicle, CFD with high accuracy is needed. To improve its accuracy, spatial resolution of CFD should be based on flow phenomenon. For this purpose, to compare aerodynamic force, pressure profile and velocity vector map derived from CFD with experimental data is important, but there are some difficulties to obtain pressure profile and velocity vector map for actual vehicles. At the point of pressure measurement for vehicles, installation of pressure taps to the surface of vehicle, i.e., fuel tank and battery, is a problem. A new measurement method developed in this study enables measurement of surface pressure of any desired points. Also, the flexibility of its shape and measuring point makes the installation a lot easier than the conventional pressure measurement method.

Bioethanol is being used as an alternative fuel throughout the world based on considerations of reduction of CO2 emissions and sustainability. It is widely known that ethanol has an advantage of high anti-knock quality. In order to use the ethanol in ethanol-blended gasoline to control knocking, the research discussed in this paper sought to develop a fuel separation system that would separate ethanol-blended gasoline into a high-octane-number fuel (high-ethanol-concentration fuel) and a low-octane-number fuel (low-ethanol-concentration fuel) in the vehicle. The research developed a small fuel separation system, and employed a layout in which the system was fitted in the fuel tank based on considerations of reducing the effect on cabin space and maintaining safety in the event of a collision. The total volume of the components fitted in the fuel tank is 6.6 liters.

The purpose of this research is to develop a prediction technique that can be used in the development of port fuel-injection (hereinafter called PFI) gasoline engines, especially for general purpose small utility engines. Utility engines have two contradictory desirable aspects: compactness and high-power at wide open throttle. Therefore, applying the port fuel injector to utility engines presents a unique intractableness that is different from application to automobiles or motorcycles. At the condition of wide open throttle, a large amount of fuel is required to output high power, and injected fuel is deposited as a wall film on the intake port wall. Despite the fuel rich condition, emissions are required to be kept under a certain level. Thus, it is significant to understand the wall film phenomenon and control film thickness in the intake ports.

The field of diesel combustion research is producing numerous reports on studies of premixed combustion, which promises simultaneous reduction of both NOx and soot, in order to meet increasingly stringent regulations on harmful emissions from automobiles. However, although premixed combustion can simultaneously reduce both NOx and soot, certain issues have been pointed out, including the fact that it emits greater quantities of unburned HC and CO gases and the fact that it limits the operating range. Furthermore, this combustion method sets the ignition delay longer with the aim of promoting the mixing of fuel and air. This raises issues with the product due to the combustion instability and sensitivity to the uneven fuel properties that are found on the market, the capability of the engine response under transient conditions, the deterioration in combustion noise, and so on.

Recently, the use of ethanol blended fuel is growing worldwide. Therefore, there is increasing needs for addressing issues relating to ethanol blended fuel use in gasoline engine fuel supply systems. In this paper, we focused on one of such issues, which is the reduced life of a multi-layered fuel filter used at inlet side of a fuel pump when it is used with ethanol blended fuel. In this study, we clarified that ethanol blended fuel tends to disperse dust particles contained in fuel to a greater extent than gasoline, and that it has a mechanism to accelerate clogging by concentrating the clogging only on the finest layer of the multi-layered filter. Also, in the process of clarifying this principle, we confirmed that dust particles dispersed by ethanol are coagulated when passing through the filter layers.

Bio-ethanol is one of the candidates for automotive alternative fuels. For reduction of carbon dioxide emissions, it is important to investigate its optimum combustion procedure. This study has explored effect of ethanol fuels on HCCI-SI hybrid combustion using dual fuel injection (DFI). Steady and transient characteristics of the HCCI-SI hybrid combustion were evaluated using a single cylinder engine and a four-cylinder engine equipped with two port injectors and a direct injector. The experimental results indicated that DFI has the potential for optimizing ignition timing of HCCI combustion and for suppressing knock in SI combustion under fixed compression ratio. The HCCI-SI hybrid combustion using DFI achieved increasing efficiency compared to conventional SI combustion.

In an attempt for further improvement of exhaust gas purification and fuel economy, an electronically controlled fuel injection (FI) system has been applied to small size motorcycles. As compared to a similar system for cars, FI systems for small two wheeled vehicles are required to be small, lightweight and low cost. In order to meet these requirements, authors developed a new control method of determining the required quantity of fuel. This system removes the intake pressure sensor of the intake pipe that exists in the conventional FI system. From correlating the peak intake pressure in the intake pipe with the quantity of intake air closely, the peak intake pressure is estimated by using rotation change of the crankshaft. The required quantity of fuel is injected into the engine intake pipe determined by the map set up in the peak intake pressure and the fuel injection period.

A compact, low-cost fuel pump module has been developed for use in motorcycles with a small-displacement engine. Various considerations are given to make the module as compact as possible. The pump motor, which is one of the major component parts, is down-sized specifically for applications to small-displacement engines. The pressure regulator uses a simple construction consisting only of a ball and a spring without a diaphragm. Especially noteworthy is that with the volume reduced by approximately 40% from the conventional pressure regulator while using the construction that reduces self-excited vibrations caused by fuel pressure pulsations, the pressure regulator contributes significantly to the down-sizing and cost reduction of the module. Furthermore, the down-sized module remarkably reduces the size of fuel pump mount surface, allowing a modification from the flat-surface sealing to the radial sealing.

As a result of recent EPA (U.S. Environmental Protection Agency) gasoline permeation control regulations, the fuel tanks on motorcycles and ATVs (All-Terrain Vehicles) are required to change to lower gasoline permeation performance on 2008 models. Therefore, we determined to use a multilayer plastic fuel tank. There are some molding issues that are peculiar to motorcycle and ATV fuel tanks. First, when the insert is blow molded, there is a reduction in welding strength. Second, peeling of the adhesion occurs on impact in the inserted parts. Third, saddle shapes with large ductility deformation are easy to be punctured during molding. Finally, the appearance of the fuel tank is not acceptable. In order to address the first issue, the welding performance, the drawdown of parison and the melting damage of insert parts were balanced, focusing attention to the temperatures of the parison and the insert.

In an attempt to decrease the amount of CO2 emitted by engines and yet improve engine output power, various approaches to the development of variable valve-lift mechanisms and the application of direct fuel injection and supercharger mechanisms are rapidly gaining popularity. In the case of the swing motion which takes place in variable valve-lift mechanisms, the relative speed between the two components reaches zero at the location where the load is high and the oil film tends to break, thereby leading to wear. Furthermore, the use of a supercharger and a direct injection device generates soot, which promotes further wear. Therefore establishing a reliable method for estimating wear has become a pressing issue. Wear problems caused by the swing motion occur during boundary lubrication, and we have devised a solution for them.

In recent years, the increased use of electric power steering in vehicles has increased the importance of issues such as making systems more compact and lightweight, and dealing with increased development man-hours. To increase development efficiency, the use of a “Hardware in the loop simulator” (HILS) is being tested to shift from the previous development method that relied on a driver's subjective evaluation in an actual vehicle test to bench-test development. Using HILS enables tasks such as specification studies, performance forecasts, issue identification and countermeasure proposals to be performed at an early stage of development even when there is no prototype vehicle. This report describes a case study of using HILS to solve the issues of reducing the load by adjusting the geometric specifications around the kingpin and eliminating the tradeoff by adding a new EPS control algorithm in order to make the electric power steering (EPS) more compact and lightweight.

In conventional electronically controlled fuel injection systems, when the battery is inadequately charged, the small amount of electric power generated from the alternator by the kick starter operation is consumed by all electrical loads including the battery. This causes a voltage drop, hence the fuel injection system does not function due to a power shortage. To eliminate the power shortage, an installed relay circuit opens all electric loads other than the fuel injection system. This allows the fuel injection system to use all the electric power generated by the kick starter operation aided through using an additionally incorporated condenser. This type of electric power control system has been incorporated into the ECU. Thus, the control system has been realized that permits starting of an engine by using the kick-starter even when the battery is completely discharged.

A fuel-cell-vehicle has been provided with an electric-double-layer-capacitor system (capacitor) to act as a back-up power source. The fuel cells and the capacitor have different voltages when the system is started, and for this reason the system could not be reconnected by relays. A VCU (Voltage and current Control Unit) has been positioned in the path of electrical connection between the fuel cells and the capacitor as a method of dealing with this issue. The VCU enables the charging of the capacitor to be controlled in order to equalize the voltage of the two power sources and allow a connection.

In this study, a spark plug sensor for in-situ fuel concentration measurement was applied to a port injected lean-burn engine. Laser infrared absorption method was employed and a 3.392 μm He-Ne laser that coincides with the absorption line of hydrocarbons was used as a light source. In this engine, the secondary valve lift height of intake system was controlled to obtain appropriate swirl and tumble flow in order to achieve lean-burn with the characteristics of intake flow. For such in-cylinder stratified mixture distribution, the fuel concentration near the spark plug is very important factor that affects the combustion characteristics. Therefore, the mixture formation process near the spark plug was investigated with changing fuel injection timing. Under the intake stroke, the timing that fuel passed through near the spark plug depended largely on the fuel injection timing.

A variable cooling system has been developed for scooters equipped with an air cooled, four-stroke, single cylinder gasoline engine. This system opens or closes louver located at the cooling air inlet using an oil-temperature sensitive actuator. When the engine is cold or the engine load is low, the louver shut off the cooling air for a quick warm-up and for maintaining the engine oil temperature high to reduce the friction losses that occur with low oil temperature while eliminating the loss from driving the cooling fan as well. The quick warm-up also decreases supplementary fuel injections necessary when the engine is cold. Consequently, fuel economy improvement by 3.3% was realized in running condition of the Urban Driving Cycle.

A three-motor hybrid system suitable for a super sports car was developed. This system features high power, light weight and high response, and has high cooling performance for high-load operation such as circuit driving. The power plant drives the rear wheels using the combination of a midship-mounted V6 twin-turbo engine, the direct drive motor of a hybrid system mounted directly on the engine, and a 9-speed dual-clutch transmission (DCT). The front wheels are driven by a twin-motor unit (TMU), and the size and weight of the Intelligent Power Unit (IPU) that supplies electric power to the TMU has been reduced to enable mounting behind the seats inside the cabin. In addition, the IPU uses air-conditioner cooperative cooling to enhance the cooling performance. As a result, assist is performed even during high-load operation.

As technologies for simultaneously maintaining the current high thermal efficiency of diesel engines and reducing particulate matter (PM) and nitrogen oxide (NOX) emissions, many new combustion concepts have been proposed, including premixed charge compression ignition (PCCI) and low-temperature combustion[1]. However, it is well known that since such new combustion techniques precisely control combustion temperatures and local air-fuel ratios by varying the amount of air, the exhaust gas recirculation (EGR) ratio and the fuel injection timing, they have the issues of being less stable than conventional combustion techniques and of performance that is subject to variance in the fuel and driving conditions. This study concerns a system that addresses these issues by detecting the ignition timing with in-cylinder pressure sensors and by controlling the fuel injection timing and the amount of EGR for optimum combustion onboard.