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A great deal of interest is focused on Homogeneous Charge Compression Ignition (HCCI) combustion today as a combustion system enabling internal combustion engines to attain higher efficiency and cleaner exhaust emissions. Because the air-fuel mixture is compression-ignited in an HCCI engine, control of the ignition timing is a key issue. Additionally, because the mixture ignites simultaneously at multiple locations in the combustion chamber, it is necessary to control the resultant rapid combustion, especially in the high-load region. Supercharging can be cited as one approach that is effective in facilitating high-load operation of HCCI engines. Supercharging increases the intake air quantity to increase the heat capacity of the working gas, thereby lowering the combustion temperature for injection of the same quantity of fuel. In this study, experiments were conducted to investigate the effects of supercharging on combustion characteristics in an HCCI engine.

A wall-resolving Large Eddy Simulation (LES) has been performed by using up to 40 billion grids with a minimum grid resolution of 0.1 mm for predicting the exterior hydrodynamic pressure fluctuations in the turbulent boundary layers of a test car with simplified geometry. At several sampling points on the car surface, which included a point on the side window, the door panel, and the front fender panel, the computed hydrodynamic pressure fluctuations were compared with those measured by microphones installed on the surface of the car in a wind tunnel, and effects of the grid resolution on the accuracy of the predicted frequency spectra were discussed. The power spectra of the pressure fluctuations computed with 5 billion grid LES agreed reasonably well with those measured in the wind tunnel up to around 2 kHz although they had some discrepancy with the measured ones in the low and middle frequencies.

The purpose of this study is to experimentally investigate in-cylinder flows with cyclic variation in a practical part-loaded two-stroke engine. First, the in-cylinder LDV measurements are introduced, which were carried out above the port layout and the combustion chamber as well as the exhaust pipe or the transfer port together with the simultaneous pressure measurements. Second, the in-cylinder flow characteristics in different combustion groups were discussed. The in-cylinder flow and the combustion-chamber flow were not simply characterized by the pressure variation in the engine or the other passage flow in the exhaust pipe or the transfer port. Finally, the in-cylinder flow structure with three stages was shown using the vector variation analysis and the drawing of the velocity profiles in the engine parts.

The purpose of this study was to detect a misfiring cycle in terms of the transfer-passage and the exhaust-pipe flow rate by experimental measurements. Simultaneous measurements of flow rates and in-cylinder pressure were carried out. The flow rate data were grouped into the different combustion classes by the in-cylinder pressure. A large flow rate of exhaust blow-down and a large reverse flow rate were observed in the cycle before misfiring, compared with in the cycle before firing. It showed that high concentration of the residual burnt gas in the cylinder was the main source of misfiring, this feature was also demonstrated by the complementary measurement of CO and CO2 concentrations.

The purpose of this study is to show cycle-to-cycle combustion variation in transient conditions of quick throttle opening and to control the combustion fluctuation improve acceleration in a two-stroke motorcycle engine. Two phases of engine operation were focused on: the low-load condition before quick throttle opening, and the transient condition after quick throttle opening. The time-series variation of the heat release rate based on the in-cylinder pressure, the engine-speed and the exhaust pressure variation were measured simultaneously, in an engine with a new multiple-timing-ignition-system, and in an engine with a modified exhaust port. Stable ignition performance and fast burning velocity were the keys to attaining smooth acceleration.

A resin coating was applied to a piston skirt for use in an internal combustion engine to reduce the frictional resistance on its surface. The purpose of the authors' study was to observe the change in surface states with the addition of nylon and graphite to the coating as solid lubricant particles in order to investigate the tribological properties of the surface. The authors observed self-formed microdimples on the resin surface when nylon particles were added to the polyamide-imide (PAI) coating material. These microdimples functioned as oil reservoirs similar in size to the nylon particles. The authors used PAI as a binder, and graphite particles (5 μm) and two different grades (5 and 10 μm) of nylon-12 particles as additives. These materials were mixed in a solvent, and an aluminum test sample was coated. The test sample was then heated in an oven to cure the PAI. Next, the texture of the surface was observed.

Various sensors including throttle position sensors (TPS), manifold pressure sensors (MPS), crank angle sensors, engine temperature sensors, and oxygen sensors are mounted in electronically controlled fuel injection (FI) systems to accurately regulate the air-fuel ratio according to the operating state and operating environment. Among these vehicle-mounted sensors, TPS has functions for detecting a fully-closed throttle and estimating intake air volume by the amount of throttle opening. Currently, we have conducted a study on transferring TPS functions into the MPS (manifold pressure sensor) in order to eliminate the TPS. Here we report on detecting a fully-closed throttle for achieving fuel cut control (FCC) and idle speed control (ISC) in fuel injection systems. We contrived a means for fully-closed throttle detection during ISC and controlling changes in the bypass opening during FCC in order to accurately judge each fully-closed throttle state via the manifold pressure.

When the planing craft with outboard motor is running, cavitation occurs around the surface of propeller and lower unit of outboard motor. Cavitation has been classified under several categories by the feature and cause of occurrence. Among them, cloud cavitation and root cavitation lead to erosion damage on the surface of lower unit and propeller. To prevent from poor appearance or performance deterioration of outboard motor by erosion damage, it is important problem to predict the erosion occurrence. Currently we can predict the cavitation phenomena sufficiently, but the area of cavitation does not necessarily correspond with the area of erosion. In this study, we present the new method to predict the area of erosion due to cavitation using CFD (computer fluid dynamics) analysis. In order to evaluate the accuracy of erosion occurrence simulation, the simulation results are compared against the result of a full-scale cruising test.

The purpose of this study was to measure the distribution and volume of liquid film adhering to the walls after the injection of fuel by an injector of a port-injection engine using the laser induced fluorescence (LIF) method while changing the fuel pressure and the angle of injection, and to consider how adhesion can be reduced in order to decrease the exhaust emission of gasoline engine. Using a high-speed camera, we filmed the adhesion and evaporation of liquid film in time series. Perylene, used here as a fluorescence dye, was blended with a fuel comprising toluene and n-heptane, and the mixture was injected onto a solid surface using a port-injection injector. UVLED with a maximum output wavelength of 375 nm was used as the exciting light. To more accurately measure the volume of fuel adhesion, it was necessary to correct the unevenness of the light source.

The electrodeposition painting can make a coat adhere not only to the exterior surface but also on the inside of an object, and has excellent corrosion resistance. Therefore, it is widely used as paint for anti-corrosion to various vehicles. In electrodeposition painting, by the electricity from an electrode flowing into the surface of an object through paint solution, a paint deposits to the surface of an object and a paint film is formed. Therefore, if the object is simply in contact with paint solution, a paint film will not necessarily be formed. For example, even if paint solution has touched, since the electrical resistance of paint solution is not high, sufficient current flows through the outside of a motorcycle frame, nor the inner surface of the automobile body and a paint film may not be formed. In order to check the paint film thickness of electrodeposition painting conventionally, it was measuring by disassembling the actually painted object.

Traditionally, a Boundary Element Method (BEM) is often used for a radiation noise analysis. In recent years, to define an infinite region, a Finite Element Method (FEM) that can use an infinite boundary condition has been developed. However, studies on the radiation noise analysis by the FEM are few. Recently a number of an electric scooter has been increased. One of development issues is a radiation noise by a vibration of a wall surface of a swing-arm. In this paper, the vibration of the wall surface of the swing-arm is calculated, and a sound pressure level (SPL) of the radiation noise is calculated using a result of the frequency response analysis. And compare results of an experimental and an analytical sound pressure, its results were matched to within 5% error. Furthermore we used the method of this paper, proposed the model to reduce the radiation noise 10dB. Then we compare with the FEM and the BEM to verify the computation time and the mesh size.

Lead-added free-cutting steel has been used by many parts which need high machinability because lead improves chip friability and drill life. However, the demand of lead reduction increases in recent years, because of environmental impact substance reduction. Therefore, we developed lead-free crankshaft for motorcycle. Until now, crankshaft for motorcycle has been manufactured with lead-added free-cutting steel by a following process; Hot-Forging - Quenching and Tempering (QT) - Prior Machining - Nitrocarburizing - Finishing process because of strength and machinability. When we tried to change steel to lead-free, we examined to change to sulfur-added free-cutting steel. However, chip friability of sulfur-added free-cutting steel is inferior to lead one. Thus, we concerned about increase in machining expense. Then, heat-treatment after forging was examined to change from QT to normalizing for reducing the heat-treatment expense.

Unresolved issues of Homogeneous Charge Compression Ignition (HCCI) combustion include an extremely rapid pressure rise on the high load side and resultant knocking. Studies conducted to date have examined ways of expanding the region of stable HCCI combustion on the high load side such as by applying supercharging or recirculating exhaust gas (EGR). However, the effect of applying EGR gas to supercharged HCCI combustion and the mechanisms involved are not fully understood. In this study, the effect of EGR gas components on HCCI combustion was investigated by conducting experiments in which external EGR gas was applied to supercharged HCCI combustion and also experiments in which nitrogen (N2) and carbon dioxide (CO2) were individually injected into the intake air pipe to simulate EGR gas components. In addition, HCCI combustion reactions were analyzed by conducting chemical kinetic simulations under the same conditions as those of the experiments.