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A fuel control method to reduce the harmful exhaust gas from SI engines is proposed. As is well known, both the amplitude and the frequency of the limit cycle in a conventional air-fuel ratio control system are determined uniquely by parameters in the system. And this limits our making full use of the oxygen storage effect of TWC. A simple model of TWC reaction revealed the relationship between maximum conversion efficiency and both the amplitude and the frequency in a air fuel control system. It also revealed that TWC conversion efficiency attained to maximum levels when both the amplitude and the frequency of the limit cycle are selected so as to make full use of the oxygen storage effect of TWC. In order to achieve this, it is necessary to vary both the amplitude and the frequency arbitrarily.

A flexible fuel vehicle (FFV) was evaluated through various tests for its potential as an alternative to the conventional gasoline vehicle. This paper presents the systems incorporated in the FFV and the test results. 50,000 mile emission durability tests were also performed and the potential of the FFV as a “Low Emission Vehicle” was assessed. As the result of extensive engineering work, we successfully developed a Galant FFV which exhibits very good durability and reliability. The emission control system which we have developed demonstrated that the vehicle has a good potential to comply with the California formaldehyde emission standard of 15 mg/mile. However, due to the large portion of unburnt methanol in the tail-pipe emissions, FFVs will have more difficulty than gasoline vehicles in meeting non-methane organic gas (NMOG) standards applicable to “Low Emission Vehicles”.

In order to meet increasing demands for safety and comfort in a vehicle compartment, automatic adjustment of seat, mirrors, steering wheel has been developed. The multiplex wiring system was constructed for the automatic adjustment of the cockpit elements to drivers preferred positions or to physique-matched settings based on ergonomic data. This paper describes the construction of the multiplex system and functions of automatic adjustment of the cockpit elements for comfortable driving position and better visibility.

Beta Ti alloy valve spring retainers are newly developed for use in mass produced automobiles for the first time. Ti alloy valve spring retainers vith a weight saving of 42%, compared to steel retainers, have reduced the inertial weight of the valve train components by 6%. And this weight reduction has the benefit of increasing the upper limit of the engine speed, which improves the engine performance. Ti alloy valve spring retainers are cold forged by the conventional fabrication facilities for steel retainers, using Ti-22V-4Al (the beta Ti alloy) which possesses excellent cold workability in a solution treated condition. Oxygen surface hardening is applied to protect Ti alloy valve spring retainers from wear damage. In addition, aging treatment and shot blasting are performed to improve strength and stiffness of valve retainers.

This paper describes a control strategy for autonomous vehicles in an intelligent vehicle/highway system. The control concept aims at the compatibility of passenger riding comfort and vehicle controllability. The main subject of this paper is lateral control of vehicles. In order to analyze riding comfort, we have experimented on the lateral riding comfort during a lane change. It was found that the riding comfort is mainly related to the jerk more than the acceleration, and that the trajectory pattern is important. According to the experimental results, a motion control system was designed. We found through the computer simulation and the experiment with an autonomous test vehicle that comfortable ride is realized along with system stability. Lastly, in order to apply this strategy to the longitudinal direction, we have experimented on the longitudinal acceleration with the test vehicle. The results shows that the same strategy is applicable to the longitudinal direction.

The authors developed, for use in diesel engines, ceramic tappets cast in aluminum alloy that drastically improved wear resistance and valve train dynamics. The ceramic tappets consist of two parts: a ceramic head, which contacts the cam and push rod, and a tappet body made of aluminum alloy. Concerning the ceramic, silicon nitride was the best material of the three ceramics evaluated in the tests and the sliding surface, in contact with the cam and push rod, was left unground. As for the aluminum alloy, hyper-eutectic aluminum-silicon alloy with a controlled pro-eutectic silicon size was selected. A reliability analysis using the finite-element method (FEM) was also made on the structure of the ceramic tappet for enhanced durability and reliability. The combination of this tappet and a cam made of hardened ductile cast iron, hardened steel, or chilled cast iron, respectively exhibits excellent wear resistance.

The gasoline direct injection engine starts significantly faster than a conventional engine. Fuel can be injected into the cylinder during the compression stroke at the same time of cranking start. When the spark plug ignites the mixture at the end of compression stroke, the engine has its first combustion, that is, the first combustion occurs within 0.2 sec after the start of cranking. This unique characteristic of quick startability has realized a idle stop system, which enables drivers to operate the vehicle in a natural manner.

A stratified-charge lean-burn engine is newly developed for the purpose of energy saving and carbon dioxide reduction to minimize the global warming. The engine, named MVV(Mitsubishi Vertical Vortex)engine, is based on the unique vertical vortex technology which realizes stable combustion even with lean mixture without any additional device. And it also has another feature of “all range air-to-fuel ratio feedback control system” utilizing linear air-to-fuel ratio sensor. This paper describes various technologies developed in this engine.

A trap system has been developed that collects particulate using two small filters and regenerates alternately by electric heaters. This system contains a new idea in detection of the amount of particulate accumulation in the filters. The system counts the amount using a particulate accumulation rate map which is a function of the engine load and speed. In vehicle test with this trap system, the particulate collection efficiency and the regeneration efficiency were proved to be high enough for practical use. The test results also showed that the shutdown performance of the route switch valve greatly influenced the regeneration efficiency.

A new prototype oxygen storage componented oxygen sensor has been developed which shows significant emission reductions of a 3-way catalyst system. This sensor is composed of ceria, as an oxygen storage component and supported pellets as a buffer layer surrounding the protective coating of the sensor element. This sensor offers a more rapid response than conventional ones under lean and rich fuel mixture excursions, which is caused by CO or O2 electrode poisoning.

In previous studies(1)(2), the acceleration performance of vehicles equipped with torque converter has been analysed with the assumption that the converter characteristic was under continued steady-state. However, in case of sharp acceleration of the fluid flow in the converter from inactive flow condition, which would occur at wide-open throttle starting, it is not possible to accurately analyse the vehicle performance at immediately after starting if the converter characteristic is assumed to remain under steady-state condition. In this paper, the transient phenomenon in the converter is verified by applying the theory of angular momentum and the concept of energy balance through the converter elements providing with a dynamic-model for the driveline. The present study has clarified the effect of the transient converter characteristic, at sharp starting, on the acceleration performance.

A high-performance road profile measuring system has developed. The measuring system consists of four laser displacement sensors and an optical speed sensor. It has the advantage of making high-accuracy measurements during a regular run, on a public road, and without any traffic restriction. The measurement is hardly affected by bouncing and pitching motions of the vehicle. The four displacement sensors are arranged at unequal intervals in the direction of vehicle. A road profile is calculated from sensor outputs. This paper describes not only the development of this unique measuring system but also its application to a vehicle behavior. Significant measurements of typical and peculiar public roads in Japan and Northern Europe by the measuring vehicle have been performed for the last few years. The features of these roads are described by the power spectrum densities and the profiles.

An investigation of anti-corrosion steel sheets (non-galvanized) which contain copper for automobile body parts has been conducted. Copper additives accelerate the formation of amorphous substrates. These substrates decrease the rate of corrosion. In order to retain the steel's formability and weldability, the contents of the alloying elements have been optimized. As a result, this newly developed steel sheet can be used for many different applications such as door sashes and door panels of mass produced cars. This paper describes the key properties of the newly developed steel sheet and additionally the mechanism of corrosion prevention, weldability, formability, and so on.

Flow and flame structure visualization and modeling were performed to clarify the characteristics of bulk flow, turbulence and mixing in a four-valve engine to adopt the lean combustion concept named “Barrel-Stratification” to the larger displacement center-spark four-valve engine. It was found that the partitions provided in the intake port and the tumble-control piston with a curved-top configuration were effective to enhance the lean combustion of such an engine. By these methods, the fuel distribution in the intake port and the in-cylinder bulk flow structure are optimized, so that the relatively rich mixture zone is arranged around the spark plug. The tumble-control piston also contributes to optimize the flow field structure after the distortion of tumble and to enable stable lean combustion.

This paper presents a new torque distribution system-“Right/Left Torque Control System”, aimed at improving a vehicle's cornering properties by using yaw moment control. The torque transfer mechanisms of this system have been analyzed. Also, a yaw moment control algorithm using yaw rate feedback control has been designed. Next, vehicle cornering properties were evaluated using numerical simulation developed from data taken from an actual vehicle. As a result, improvements were achieved in the maneuverability and stability of a vehicle during cornering.

Passenger cars with sunroofs sometimes experience a low frequency pulsation noise called “wind throb” when traveling with the roof open. This “wind throb” should be suppressed because it is an unpleasant noise which can adversely affect the acoustic environment inside a car. In this paper, 3-dimensional numerical flow analysis is applied around a car body to investigate the wind throb phenomenon. The computational scheme and the modeling method of the car body is first described. A flow visualization test in a water tunnel was completed for the simple car body shape to compare against the numerical procedure. The numerical and the visualized results compared well and the numerical simulation method employed was considered to be a reliable tool to analyze the wind throb phenomenon. Calculated results of pressure and vorticity distribution in the sunroof opening were analyzed with the spectrum of pressure fluctuation at the sunroof opening with and without a deflector.

Mitsubishi has developed the new, compact, water-cooled vertical type 2-cylinder diesel engine model K2AS and brought it to market in spring of '82. The K2AS is a small-sized engine of 451 cc total displacement and 10HP/3600 rpm maximum output. Its weight of 58 kg is light enough to use this diesel engine for various machines which have formerly been driven by gasoline engines. The well matched combustion chamber and injection system realize low fuel consumption, low noise and easy engine starting. High durability is also assured by various kinds of reliability evaluation. Features of K2AS are outlined below.

Mitsubishi Motors Corporation presents the newly-developed 2-liter engine, which we have named SIRIUS DASH. The SIRIUS DASH engine, with its compound intake system, features great performance in both high and low speed ranges while keeping fuel consumption low. The compound intake system operates the 3 valves in 2 stages. When engine speed is low, just one intake valve is used, but when engine speed increases, two intake valves are used. And to make this engine truly extraordinary, we added a turbocharger with an intercooler, and equipped the whole thing with a total electonic control system. Generally, high performance engines which have large inlet ports and high speed type valve timing enabling them to intake sufficient air for high performance at high speeds. The problem is here that when speed is dropped, combustion becomes unstable at the expense of torque and fuel consumption.

An analysis of the static behavior of T-shaped joint is presented. Advanced testings by laser holography and infrared ray stress wave analyzers verified the surface deformation and the stress concentration of joint area, which are very important factors of thin-walled joint stiffness. The definition of structural joint stiffness is attempted, and the relationship between structural joint stiffness and sizes(dimension) of the constructing members is obtained in case of a thin-walled T-shaped member with rectangular cross section. The parametric study to accomplish weight reduction, while maintaining the necessary structural joint stiffness, is described in case of Rocker to Center pillar. The numerical analysis of body structure considering the structural joint stiffness shows better accuracy as compared with the analysis with the joint assumed rigid.

The adoption of the diesel engine EGR systems, and increased uses of alcohol in spark ignited engines require wear resistant and low maintenance valve trains. Silicon nitride ceramic inserts were pressureless-sintered and successfully die-cast in rocker arms contacting the overhead cams in the valve trains. As fired, the insert sliding surface was fine and precise, eliminating any further processing. The comosite structure was machined with the sliding surface as a reference plane. Beside inherent high wear resistance, these lighter inserts reduced inertial forces of the trains and the torque required to drive the cams. The hard, brittle ceramics and a softer, more elastic aluminum alloy made the structure more durable and reliable. The process of development includes characterization, screening, manufacturing and quality control of the materials, and determination of wear resistance and reliability for this new structure.