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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.

Three zone mixture preparation model, assuming that fuel and air are distributed in three separate zones, fuel air and mixture zone, was proposed. Air Utilization Efficiency derived from the model was used to evaluate the mixing nonuniformity. Effect of the large scale nonisotropic turbulence downstream of the dimple or edge in the intake port of MPI engine on the convective mass transfer from fuel film was clarified by the proposed nondimensional index, Local Sherwood Number. It was found that when the fuel is injected toward the wall where large scale turbulence exists, almost all of the fuel is seeded in the air passing the region at the beginning of the intake process, resulting in the time-resolved nonuniformity of the mixture strength at the intake valve. Using the Air Utilization Efficiency, it was elucidated that time-resolved mixing nonuniformity at intake valves induces spatially nonuniform fuel/air distribution in the cylinder.

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.

The accuracy of real-time A/F measurement at engine test benches has been improved with a modified equation to calculate A/F from exhaust gas composition. In addition to CO, CO2, total hydrocarbon (THC) and O2, the proposed equation includes NO and NO2 concentration as variables. In an attempt to improve the accuracy of the assumed constants in the equation, experiments have been conducted using automotive exhaust H2O and H2 analyzers. The accuracy of the proposed equation was proven through experiments and it was also found useful for precise evaluation of three-way catalyst or oxygen sensor characteristics.

This year (1989) Mitsubishi Motors Corp. introduced, on some models, a newly-developed Hydraulic Coupling Uint (HCU), by which 2WD vehicles can be converted into 4WD ones in the same way as done by a viscous coupling (VC). This HCU is similar in the configuration to a vane pump: the oil discharge is returned to the suction chamber through a number of orifices. The rotor and cam ring (housing) are respectively connected to the two shafts; either of the one with the front wheels and the other with the rear wheels. Accordingly, it works as a slip-sensitive differential like a VC while it has a merit of progressive and parabolic torque-response characteristic, which offers stronger traction and acceleration capability and also minimizes tight-corner braking. This paper discusses primarily the configurations, functions and test results of the HCU and also presents an overview on further development possibilities of the 4WD system.

In order to investigate the effects of high injection pressure on engine performance and exhaust emissions, some experimental high injection pressure in-line pumps were made and tested. Increasing fuel spray momentum by high injection pressure could reduce smoke emission, but excessive increase in injection pressure was found not so effective in further reducing smoke emission. Accordingly, a high injection pressure should be accomplished within the low engine speed range a feature that has been very difficult to achieve for a conventional in-line pump. An electronic controlled injection-rate-control pump with a variable prestroke mechanism can provide higher injection pressure in low engine speed range and advances injection timing in high engine speed range. This pump can improve fuel economy in low engine speed range and emissions (smoke and particulate) over transient FTP for HDE's.

A particulate trap oxidizer system to reduce diesel particulate emissions has been developed. This system consists of a ceramic foam filter with an optimum volume, shape, and mesh number in terms of collection efficiency, pressure loss and particulate blow-off; a catalyst with a low activated-temperature for particulate incineration and with no sulfate formation during highway driving; and a regeneration system which prevents particulate overcollection during long-term continuous low-load/low-speed driving where it is difficult to achieve self-burning of particulates with a catalytic reaction. This paper describes the development of the particulate trap oxidizer system with these technologies and presents the results of practicability evaluations and 50,000-mile vehicle durability tests.

Auto-regeneration of diesel particulate traps, particularly combustion mode of soot in a wall flow filter with fuel additives, was investigated using a diesel engine of a light duty truck and truck itself. Soot burning in the trap and regeneration were observed under any engine operating condition including prolonged idling and stop-and-go driving at 0.18g metal/1 dosage of a mixture of copper and lead in the fuels. However, trap life was limited by ash clogging due to the metallic compounds. Although the influence of metallic additives on the environment was debatable, test results of the trap durability and calculations of soot burning based on the thermal ignition theory indicated that dosage and kind of fuel additives should be optimized in view of both trap life and reliability of soot burning.

This is to introduce a development history of Doubles-Combinations in Japan and a several important technological points briefly. We understand that our wide promotion of these development activities are strongly supported by the General/Technical Committee members. And totally 10 - million kirometers practical operation data included by 3 - famous Japanese fleet owners, these must be very much useful and valuable for anyone interesting those of Trailer-Combination technologies.

The effect of the use of the EGR system on the lubrication of a passenger car diesel engine was investigated. The higher the EGR rate, the more soot in the oil. And the most detrimental effect was found in valve train wear. Some engine tests, including motoring tests, were carried out to investigate the contribution of soot to valve train wear. The mechanism of cam and rocker arm wear in used oils was studied by analyzing for elements on the lubricated metal surface and subsequently the mechanism was more thoroughly studied using the four-ball test. Soot seems to act as an abrasive on the anti-wear solid film formed by the oil on the metal surface and this film contains Ca, O, P and S. Some hardware modifications and oil formulations to reduce valve train wear are also discussed.

A new combustion system - called MCA-JET- has been developed to improve combustion under the low speed, low load conditions typical of urban driving. Engines with this new system incorporate a special “jet valve”, in addition to the inlet and exhaust valves of the conventional combustion chamber, which directs air or a super-lean mixture towards the spark plug, and induces a strong swirling flow in the cylinder. This swirl persists during the compression and expansion processes, moves the mixture spirally and helps the flame to propagate. As a result, the combustion of lean mixtures, including those with exhaust gas recirculation, can be carried out rapidly and thus the fuel economy improved.

Three Japanese automobile manufacturers-Mitsubishi Motors Corp., Nissan Motor Co., Ltd., and Toyo Kogyo Co., Ltd.-have been making efforts over the past three years to design and develop effective thermal reactor-exhaust gas recirculation and catalytic converter systems suitable for small engines. The work is being done by members participating in the IIEC (Inter-Industry Emission Control) Program, and the exhaust emission levels of the concept vehicles developed by these companies have met the goal established by the IIEC Program at low mileage. Each system, however, has a characteristic relationship between exhaust emission level and loss of fuel economy. Much investigation is required, particularly with respect to durability, before any system that will fully satisfy all service requirements can be completed. This paper reports the progress of research and development of the individual concept vehicles.