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In recent years, improvements in the fuel economy and exhaust emission performance of internal combustion engines have been increasingly required by regulatory agencies. One of the salient concerns regarding general purpose engines is the larger amount of CO emissions with which they are associated, compared with CO emissions from automobile engines. To reduce CO and other exhaust emissions while maintaining high fuel efficiency, the optimization of total engine system, including various design parameters, is essential. In the engine system optimization process, cycle simulation using 0-D and 1-D engine models are highly useful. To define an optimum design, the model used for the cycle simulation must be capable of predicting the effects of various parameters on the engine performance. In this study, a model for predicting the performance of a general purpose SI (Spark Ignited) engine is developed based on the commercially available engine simulation software, GT-POWER.

In CFD (Computational Fluid Dynamics) verification of vehicle aerodynamics, detailed velocity measurements are required. The conventional 2D-PIV (Two Dimensional Particle Image Velocimetry) needs at least twice the number of operations to measure the three components of velocity ( u,v,w ), thus it is difficult to set up precise measurement positions. Furthermore, there are some areas where measurements are rendered impossible due to the relative position of the object and the optical system. That is why the acquisition of detailed velocity data around a vehicle has not yet been attained. In this study, a detailed velocity measurement was conducted using a 3D-PIV measurement system. The measurement target was a quarter scale SAE standard vehicle model. The wind tunnel system which was also designed for a quarter scale car model was utilized. It consisted of a moving belt and a boundary suction system.

Titanium alloy for forging and pure titanium material for exhaust systems have been developed. The forging alloy will be applied to production of lightweight motorcycle frames and the pure titanium will be applied to improve engine performance. The materials have been made inexpensive by the use of off-grade sponge that includes many impurities for production of titanium ingot. Stable characteristics have been obtained by controlling oxygen equivalent after setting the volume of tolerable impurities by considering mechanical properties and production engineering. In spite of low-cost, the material provides the same design strength compared to conventional material, and enables parts production with existing equipment. A review of manufacturing and surface treatment processes indicated a reduction in the price of titanium parts produced with this new material.

Crankshafts of motorcycles require high strength, high reliability and low manufacturing cost. Recently, a reduction of Pb content in the free-cutting steel, which is harmful substance, is required. In order to satisfy such requirements, we started the development of Pb-free free-cutting steel which simultaneously enabled the omission of the normalizing process. For the omission of normalizing process, we adjusted the content of Carbon, Manganese and Nitrogen of the steel. This developed steel can obtain adequate hardness and fine microstructure by air-cooling after forging. Pb-free free-cutting steel was developed based on Calcium-sulfur free-cutting steel. Pb free-cutting steel is excellent in cutting chips frangibility in lathe process. We thought that it was necessary that cutting chips frangibility of developed steel was equal to Pb free-cutting steel. It was found that cutting chips frangibility depend on a non-metallic inclusion's composition, shape and dispersion.

There is a movement to apply emission control in a marine engine as well due to high public awareness of environmental concern in the United States. We started at the development of 3-seater Personal Watercraft (PWC) equipped with 4-stroke engines in taking environment conformity and potential into account. The PWC employed series 4-cylinder 1100cc displacement engine that has been used for mass production motorcycles. The engine was modified to satisfy requirements for PWC, as a marine engine, such as performance function and corrosion. In order to achieve greater or equal power/weight ratio as against two-stroke PWCs, a four-stroke engine for PWC with an exhaust turbo charger was developed. As a result, we succeeded in developing an engine that attained top-level running performance and durability superior to competitors' 2-stroke engines.

A numerical calculation method, which enables the analysis of gear train behavior including non-linear elements in a motorcycle engine, was established. During the modeling process, it was confirmed that factors such as bearing distortion, radial bearing clearance and elastic deformation of a tooth flank could not be neglected because they effect the rotation behavior. To keep a high accuracy, those factors were included in the simulation model, after they were converted into the rigidity elements along the rotational direction of each gear model. In addition, the model was combined with a crankshaft behavior calculation model for a driving and excitation source. A time domain numerical integration method was used to perform the transient response simulation across a wide range of engine speeds. A jump phenomenon of response behavior of the driven gear was predicted that is a characteristic of non-linear response. The phenomenon was also observed in a physical test.

Gas chromatographic methods for analyzing hydrocarbon species in vehicle exhaust emissions were compared in terms of their collection efficiency, detection limit, repeatability and number of species detected using cylinder gas and tailpipe emission samples. The main methods compared were a Tenax cold trap injection (TCT) method (C5-C12 HCs) and a cold trap injection (CTI) method (C2-C4 HCs; C5-C12 HCs). Our own direct (DIR) method was used to confirm the collection efficiencies. Both methods yielded good results, but the CTI method showed low collection efficiency for some C2-C4 HCs. Measurement of individual species is needed with this method for accurate analysis of tailpipe emissions. Both the CTI method and the TCT method combined with the DIR method for determining C2-C4 HCs yielded nearly the same ozone specific reactivity values for the NMHC species analyzed.

This paper introduces a new type of aluminum radiator that has been developed with the objective of high performance and light weight. Aluminum radiators have recently been replacing copper radiators because of their light weight, but the heat rejection of such conventional alminum radiators does not exceed that of copper radiators. Authors established the aluminum radiator not only being light weight but also having high performance through the following approaches. (1) Optimization of radiator core module. (2) Thickness reduction of tube and fin. (3) Development of aluminum alloys with improved corrosion resistance for tubes and fins. As a result, a new type single-row aluminum radiator has achieved 7% higher rejection at 50% lighter weight than those of copper double-row radiator.

Rollover crashes have continued to be a source of extensive research into determining both vehicle performance, and occupant restraint capabilities. Prior research has utilized various test procedures, including the FMVSS 208 dolly fixture, as a basis for evaluating vehicle and restraint performance. This research, using 2001 Nissan Pathfinder sport utility vehicles (SUVs), was conducted to update the status of passenger vehicle rollover testing, and evaluate dynamic test repeatability with a new test procedure. A series of eight rollover tests was conducted using these SUV vehicles, mounted on a modified FMVSS 208 rollover dolly fixture, with instrumented dummies in both front seat positions. This test protocol involved launching the vehicles horizontally, after snubbing the dolly fixture, and having the leading-side tires contact curbing for a trip mechanism.

A variable valving system was developed. This system has two cam profiles, one for low speed and one for high speed. A 1.2-litre DOHC experimental engine using this system was made and mounted in the body of a 2-1itre class passenger car. Test results of this car were compared to those of the same car with its original engine. The test car showed better results in every area of driving performance, in mode-fuel-econorny and in noise tests. This paper presents the mechanism, operation and test results of this variable valving system, the 1.2-litre experimental engine and this passenger car. THE PERFORMANCE AND EFFICIENCY of the passenger car gasoline engine have been greatly improved: primarily as a response to exhaust-gas emission regulations and the oil crises. These improvements have been achieved mainly through the development of control technologies to optimize many parameters such as ignition timing and air fuel ratio precisely according to driving conditions.

With conventional float-type fuel level sensor's, measurement errors when the vehicle is on an incline or going around corners. Now, a highly-accurate measuring system employing an electrostatic capacity sensor is developed for practical application. This sensor is composed of multiple electrode plates formed alone a allows accurate measurement of regaining fuel even in tanks of irregular shapes. Also, since this sensor comes a unit, it is easier to replace. The system furthermore, employs software provided with averaging, memory storage, and permittivity correction functions in order to elminate the effects of fuel level fluctuations and pressure changes within the tank during driving along with the effect of fuels with different permittivity.

Research is under way on an engine system [1] that achieves a variable compression ratio using a multiple-link mechanism between the crankshaft and pistons for the dual purpose of improving fuel economy and power output. At present, there is no database that allows direct judgment of the feasibility of the specific sliding parts in this mechanism. In this paper, the feasibility was examined by making a comparison with the sliding characteristics and material properties of conventional engine parts, for which databases exist, and using evaluation parameters based on mixed elasto-hydrodynamic (EHD) lubrication calculations. In addition, the innovations made to the mixed EHD calculation method used in this study to facilitate calculations under various lubrication conditions are also explained, including the treatment of surface roughness, wear progress and stiffness around the bearings.

Maintaining reliability of the connecting rod bearing is a very important subject, and the following is a problem that needs to be overcome. Predicting reliability has generally depended on minimum oil film thickness (M.O.F.T), but recently, the engines of passenger cars which have greater power and speed potential than conventional ones are sometimes run beyond their M.O.F.T. limit (a degree of roughness around the crank shaft's axis.) In such a case, it is so difficult to predict reliability according to M.O.F.T., that we need a new index which directly shows seizure and wear. For this purpose, we found that the crank shaft pin temperature can be a key cause of seizure and wear according to an analysis of the relationship between its temperature and the seizure and wear caused intentionally. Using this method, we confirmed that the combination of bearing and crank shaft materials is very important for preventing seizure and wear.

Nissan has developed a new GA16DE engine for use in the new 1991 Sentra. The major development aims for this engine were to achieve ample torque at low to intermediate engine speed and smooth throttle response. These aims, of course, had to be compatible with good fuel economy, quietness, maintenance-free operation and high reliability. In addition, It was necessary to achieve a compact package size despite the twin-cam design. All of those objectives have been attained through the use of a super-long and aerodynamic intake system, variable valve timing control, a low friction, maintenance-free, direct acting valve system, dual direction fuel injectors, and a two-stage cam drive system. This paper discuss the major development objectives, basic engine structure and principal component parts.

Sophisticated product designs enrich people's lives and social demands for creation of good designs are quite strong. In the automobile industry, good design quality is one of the principal factors for determining market competitiveness. In this situation where good design quality is required of every product, the authors have developed a CAD/CAM system which makes it possible to create good and accurate designs by translating designers' ideas directly and quickly into high quality CAD models, a capability that has long been desired. With this high performance system, freely formed curves and surfaces can be easily manipulated with a man-machine interface familiar to industrial designers accutomed to the conventional design process. The system also integrates photo-realistic rendering, stereography and NC milling machines for verifying differences between the realized shape and the image in the designer's mind.

As a new generation sports car engine to lead the field in the 1990s, a 3.0 liter, 60°V, type 6 cylinder, 4 cam, 24 valve engine (VG30DETT) has been developed to achieve the utmost in high performance levels and reliability. it has been mounted on the new model 300ZX and announced in the North America and Japanese markets. The VG30DETT engine is based on the previous VG30DE engine (the engine mounted on the former model 300ZX designed for the market in Japan). The main components, the major driving and the lubrication systems including such parts as the crank shaft,con-rod, cylinder block, piston, exhaust manifold, and oil pan of the VG30DE were thoroughly reviewed and revised. The VG30DETT engine is the result of redesigning the structure of the engine itself and its parts and components to assure durability under, high-level performance requirements.

An engine cycle simulation code with detailed chemical kinetics has been developed to study Homogeneous Charge Compression Ignition (HCCI) combustion with hydrogen as the fuel. In order to attain adequate combustion duration, resulting from the self-accelerating nature of the chemical reaction, fuel and temperature inhomogeneities have been brought to the calculation by considering the combustion chamber to have various temperature and fuel distributions. Calculations have been done under various conditions including both perfectly homogeneous and inhomogeneous cases, changing the degree of inhomogeneity. The results show that intake gas temperature is more dominant on ignition timing of HCCI than equivalence ratio and that there is a possibility to control HCCI by introducing appropriate temperature inhomogeneity to in-cylinder mixture.

Early activation of catalyst by quickly raising the temperature of the catalyst is effective in reducing exhaust gas during cold starts. One such technique of early activation of the catalyst by raising the exhaust temperature through substantial retardation of the ignition timing is well known. The present research focuses on the realization of quick warm-up of the catalyst by using a method in which the engine is fed with a large volume of air by feedforward control and the engine speed is controlled by retarding the ignition timing. In addition, an intake air flow control method that comprises a flow rate correction using an adaptive sliding mode controller and learning of flow rate correction coefficient has been devised to prevent control degradation because of variation in the flow rate or aging of the air device. The paper describes the methods and techniques involed in the implementation of a quick warm-up system with improved adaptability.

A robotic driver has been designed on the basis of an analysis of a human driver's action in following a given driving schedule. The self-learning algorithm enables the robot to learn the vehicle characteristics without human intervention. Based on learned relationships, the robotic driver can determine an appropriate accelerator position and execute other operations through sophisticated calculations using the future scheduled vehicle speed and vehicle characteristics data. Compensation is also provided to minimize vehicle speed error. The robotic driver can reproduce the same types of exhaust emission and fuel economy data obtained with human drivers with good repeatability. It doesn't require long preparation time. Thereby making it possible to reduce experimentation work in the vehicle development process while providing good accuracy and reliability.

This paper describes a simple engine model at idling and it applies particularly to idle speed control. Through linearization in the neighborhood of the nominal operating points (650 rpm), the engine is expressed as a reduced-order constant coefficient state variable (2 state) model. It was produced through the system order-reduction method. The strategy for controlling idle speed uses the Linear Quadratic and Integral (LQI) optimal control theory. The tracking controller was designed using a state variable engine model, and the performance index was minimized. Since state variables are artificially introduced, they are not directly accessible. Therefore, they must be estimated in accordance with a stored dynamic model (i.e. observer), in which the engine dynamic behavior is estimated on the basis of a state variable model which represents the engine's internal states, in determining controlling values.