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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.

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.

An on-line oil consumption measurement system using the SO2 tracer method has characterized automotive gasoline engine oil consumption under various engine operating conditions, including a 200-hour durability test. An oil consumption map of total engine, individual cylinder, and valve train was produced for various speed and load ranges under both steady-state and step-transient operating conditions. The effect of spark timing as an additional engine parameter on the oil consumption was also investigated. Oil consumption maps have enlightened the conventional understanding of oil consumption characteristics and broadened the areas of concern for control technologies. This paper reports the benefit of the on-line oil consumption measurement system, the result of oil consumption history over the durability test, discrete measurement of oil consumption contribution within the engine, and various oil consumption characteristics affected by engine operating conditions.

The flow vector variations at the transfer port exit in a small two-stroke engine under firing condition were investigated experimentally. A fiber LDV system was used to measure the two-dimensional velocities near the cylinder to obtain the scavenging flow vector. The scavenging flow vector variations at different engine speeds were discussed, and the relation between its vector behavior and the pressure differences between the exhaust pipe and the crankcase was examined. The measurement results show that the velocity profiles at the scavenging port were not uniform and to obtain the representative velocity at the port exit was impossible. But the major features of the scavenging flow can be understood from the pressure difference between the exhaust pipe and the crankcase. The start timing of the scavenging flow was delayed due to the residual gas and high pressure in the cylinder when the scavenging port was opened.

A direct fuel-injection two-stroke cycle engine operated with neat methanol was investigated. The engine performance, combustion and exhaust-gas characteristics were analyzed experimentally and compared for operation with a carburetor, EFI injection at the intake manifold, and EFI injection at the scavenging port. The power and the brake thermal efficiency of the direct fuel-injection engine were higher than those of engines operated with a carburetor and either of the two EFI methods. The exhausted unburnt fuel of the direct fuel-injection engine was lower than that for operation with a carburetor, and formaldehyde and the CO concentration were of the same level as for operation with the carburetor and EFI methods. The NOx concentration of the direct fuel-injection was half the level of the result of carburetor operation.

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 design of engine cylinders must satisfy two conflicting requirements, good cooling performance and ease of manufacture. A cooling system was designed to permit the circulation of engine lubricating oil as a coolant at high speed through grooves provided on the external periphery of the cylinder liner. Testing in an actual operating engine confirmed that this cooling system design not only provides better heat transfer and higher cooling performance but also simplifies the manufacturing of the cylinder since external cooling fins are not required. In this paper, we will discuss the cylinder cooling effect of the new cylinder cooling system, referring mainly to the test results of a single-cylinder motorcycle engine with lubricating oil from the crankcase used as the coolant.

A new method for rating the varnish of the piston skirt was developed by using image processing. The varnished area of a piston skirt was extracted from the developed color image in terms of the density and the color data. The figure of merit rating was calculated using a personal computer. The newly developed method makes it possible to rate varnish of the piston skirt automatically, quantitatively and quickly.

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.

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.

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.

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.

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.

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.