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In open-grille vehicle aerodynamics simulation using computational fluid dynamics, in addition to basic flow characteristics, such as turbulent flow with a Reynolds number of several million on the bluff body, it is important to accurately estimate the cooling air flow introduced from the front opening. It is therefore necessary to reproduce the detailed geometry of the entire vehicle including the engine bay as precisely as possible. However, there is a problem of generating a good-quality calculation grid with a small workload. It usually takes several days to a week for the pretreatment process to make the geometry data ‘clean’ or ‘watertight’. The authors proposed a computational method for complex geometries with a hierarchical Cartesian grid and a topology-independent immersed boundary method with dummy cells that discretize the geometry on a cell-by-cell basis and can set an imaginary point arbitrarily.

It has been widely known that thermal and fuel stratifications of in-cylinder mixture are effective to reduce in-cylinder pressure rise rate during high load HCCI operations. In order to optimize a combustion chamber design and combustion control strategy for HCCI engines with wide operational range, it is important to know quantitatively the influence of the temperature and fuel concentration distributions on ignition and heat release characteristics. At the same time, it is important to know the influence of in-cylinder flow and turbulence on the temperature and fuel concentration distributions. In this study, a numerical simulation of HCCI combustion were conducted to investigate the effects of the in-cylinder flow and turbulence, and the distributions of temperature on ignition and combustion characteristics in HCCI combustion.

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.

Cost reduction is an important development goal for small motorcycles (1). As a way to reduce costs, we have developed an electronically controlled fuel injection (hereafter FI) system without a throttle position sensor (hereafter TPS). Ordinarily, the high throttle range is controlled and computed by TPS, and the low throttle range by manifold pressure sensor (hereafter MPS). The intake airflow is estimated with consistent high precision regardless of the engine load, and the basic fuel injection is executed accordingly. Also, transient correction monitors the size of TPS changes, to inject fuel immediately when a TPS change equal to or greater than a threshold value is detected. In our development, we replaced these functions with control by MPS. For calculation of basic fuel injection quantity by MPS, we carried on the conventional method. However, MPS transient correction control had some aspects with poor tracking.

Currently, the improvement of fuel economy is the most important issue in automobile engine development. To improve fuel economy via greater thermal efficiency, the enhancement of the compression ratio and the reduction of thermal losses because of cooling have been widely investigated. These efforts to improve thermal efficiency increase the thermal load on pistons. Ensuring the reliability of the pistons and the antiknocking capacity of engines require a better understanding of piston temperature distributions through accurate measurements under various engine operating conditions. Thus, direct and indirect measurement methods have been developed to estimate the actual piston temperature. Direct methods, such as linkage-type measurements, are not typically applicable under higher engine speeds because of the poor durability of linkages.

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.

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 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.

In this study, to improve the cruising performance of planing craft with outboard motor, we have examined a estimation method of the hull attitude angle at cruising and resistance in case of changing the tilt angle and mounting position of the outboard motor by the tank test using a scale model of a hull and an outboard motor in the ship testing tank. Planing craft with outboard motor have different characteristics from large vessels. The characteristics are shown below. The hull attitude angle at cruising is different in each forward speed. The thrust accounted for a large percentage of hull weight. And the flow field around the hull changes along with the operation of the propeller. The hull attitude angle at cruising is changed by the rigging state of the outboard motor.

With the surge of environmental problems, the number of small vehicles with lower energy consumption is increasing. For such a vehicle, difficulty of achieving crashworthiness exists since it has smaller deformation space in a frontal impact accident. Smaller deformation space needs high vehicle deceleration for absorbing kinetic energy of the vehicle.The high vehicle deceleration in the event of a frontal collision may produce high occupant deceleration, resulting high chances of an occupant injury value. In this study, over 138 types of vehicle decelerations expressed by three variables in a frontal collision were examined in order to reduce occupant decelerations. Solving differential equations, following results were obtained (1) The minimum value of the maximum occupant deceleration exists.

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.

To measure the stresses acting on the crankshaft of an engine, signals must be taken out from the rapidly spinning shaft. This paper discusses the measurement of stress signals from the crankshaft using a slip ring, which is the conventional method. By developing a special fixture that allowed us to measure rotations up to 14,000 rpm and using the four-gauge method, we succeeded in accurately measuring stress waves. We confirmed that, during the motoring operation, stresses due to the secondary component of the inertia forces of the reciprocating parts are dominant and that, during the firing operation, deformation occurs at various frequency bands. As the engine speed increased, the stress amplitude increased and reached a maximum around the highest engine speed. The results of a static analysis predicted values close to actual measurements.

Anodizing is applied to improve the durability and the corrosion resistance of aluminum alloy parts of engines and car bodies. Generally, anodic oxide film is formed using direct current anodizing (DCA). However, in the case of anodizing high silicon aluminum alloy cast parts, it is difficult to derive uniform film thickness distribution. Furthermore, it takes a long treatment time which causes low productivity. In this study, the authors have developed an anodizing method by using high-frequency switching anodizing (HSA) to solve these problems. The growth process of anodic oxide film is susceptible to the metallographic structure. Thus, the typical DCA application to the high silicon aluminum alloy produces a non-uniform film thickness, while HSA has the potential to form uniform film without being affected by metallographic structure. Moreover, the current density of HSA is higher than that of DCA which reduces treatment time to 1/5 as the film formation enhances.

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.

We have developed a small-displacement gasoline direct-injection engine (1.3L). Gasoline direct-injection engines rely on ultra-lean stratified combustion to deliver significantly better fuel economy, and are already used in many practical applications. When gasoline direct-injection is applied to a small-displacement engine, however, the amount of wall wetting of fuel on the piston surface will increase because the traveled length of the fuel spray is short. This may result in problems such as smoke production, high emissions of unburned HC, and poor combustion efficiency.

In recent years, one of the most important issues in the automotive industry is the improvement of fuel economy started from the environmental problem. Making cars lighter and reducing the coefficient of friction are two ways to improve fuel economy. Reducing the weight of a cylinder, an engine component, is a typical example. The traditional, mainstream method to reduce cylinder weight has been to convert cast iron cylinder blocks into aluminum cylinder blocks by using cast iron sleeves. To further make engines lighter and more compact, however, it is desirable that cast iron sleeves be abolished, or, in other words, making cylinder blocks sleeveless. A typical technology to make cylinder blocks sleeveless is applying anti- wear coating on a bore wall. Electroplating is currently the mainstream method used for this technology. It must be noted, however, electroplating is used primarily for low-pressure cast cylinders.

We have developed an electronically controlled four-speed automatic transmission with a "D-range neutral control system" for vehicles of small piston displacements (0.66 to 1.0 liter). When the vehicle is stationary with the engine idling, the system reduces the pressure being supplied to the clutch, thereby creating a neutral clutch condition. This helps reduces fuel consumption of the stationary vehicle without intervention of the driver. The non-intervention, however, can cause discomfort for the driver when the system is engaged and disengaged as the vehicle condition (i.e., engine revolution speed, vibration or noise transmitted to the vehicle) may change noticeably. Such a cause of discomfort that surfaced during the system development stage was thoroughly investigated and successfully eliminated by improving the method of control.

Reduction of flow resistance in an intake system is essential for increasing the output of a four-stroke engine. Evaluation method regardless engine displacement or number of valves or cylinder must be required in intake system design. This study proposes intake loss coefficient as total evaluation method from flow in an intake port to charging flow into a cylinder. A three-dimensional, general-purpose Computational Fluid Dynamics (CFD) code was used to calculate an intake loss coefficient. A correlation was confirmed between an intake loss coefficient and the engine power output. Intake loss coefficients and the CFD technique may be used for efficient optimization of the shape of an intake system.

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.