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For compliance with the exhaust emission regulations, such as SULEV and STAGE4, a new air-fuel ratio control system has been developed. The concept behind this system is that the best performance of air-fuel ratio control is achieved with the minimum of man-hours of adaptation. The system consists of a section in which an engine's air-fuel ratio is fed back and a section in which the amount of oxygen stored by the catalyst is predicted and controlled. In the feedback section, a high-precision air-fuel ratio control was achieved. In the oxygen storage mass predicting and controlling section, a catalyst model was incorporated to predict the amount of oxygen in the catalyst. The important point to note in this control system is that the air-fuel ratio feedback section requires no adaptation work when using an actual engine.

This paper describes a new variable valve system that enables continuous control of valve events, i.e. time periods when the valve is open. In this system, valve events are controlled by varying the camshaft angular speed by means of an offset between the center of the camshaft and that of the medium member that transfers crankshaft torque to the camshaft. The medium member, a rotating disk, has a drive pin to enable the transfer of torque. The system has a mechanism that produces an offset between the center of the rotating disk and that of the camshaft as well as an actuator that drives the mechanism. This makes it possible to develop a compact system that can be installed in existing DOHC direct-acting valve train engines without making any major cylinder head modifications.

We have applied a non–linear control system to a hydraulically–operated continuous valve timing control (C–VTC) now in the mainstream of variable valve actuation systems. The system applied this time is a sliding mode control (SMC), which is found of late in a number of applications. Hydraulic pressure serving as the driving source of the C–VTC and the mechanism of the C–VTC have non–linear characteristics. We have investigated certain problems which occur, influenced by this non–linearity, when using a PID controller for C–VTC control. Typical issues include a large program memory size because of the large number of control parameters, a resultant considerable number of man–hours required for adaptation, and the low compatibility of response performance both for large step operations and for small step operations. Furthermore, high machining accuracy is required for the mechanical components.

In order to address global environmental problems and safety issues, software control algorithms for various automobile control units are becoming more complex every year, resulting in larger program sizes. This has made program development work more difficult, thereby increasing the number of engineering man-hour required. We have therefore developed UJ CASE, an original CASE (Computer-Aided Software Engineering) system, and make the system readily applicable to daily work with the cooperation of software engineers (users), which has produced a result of revolutionizing our program development.

Control of internal combustion engines depends on reduced idle speed and stabilized idling to improve fuel consumption.. Using a valve (ISC/V) to adjust air intake at idling, various idle speed control techniques have been proposed to improve response to variations in the target idle speed due to disturbance and to enhance speed control stability. Many conventional idle speed control systems utilize P and I control. They cannot compensate for the phase difference caused by the intake air volume between the throttle and intake valves. This leads to poor response to variations in the target idle speed and unsatisfactory control accuracy, that is, problems in preventing engine stalling and maintaining idle speed stability. To solve these problems, an idle speed control system based on fuzzy control(1)* theory is proposed. However, it is impossible to determine the control constant (membership function) theoretically.

With the recent movement to attack global environmental problems, regulations on everything from vehicle emissions to mileage are becoming stricter year by year to reduce noxious emissions. In order to meet these regulations, it is necessary to achieve higher reliability in those automotive parts which may affect emissions. Since there is a limit to how much the reliability of parts can be increased against aging and deterioration, software such as learning control utilizing air-fuel ratio lambda control, has been used. However, it has proven difficult to compensate for accuracy, by subdividing areas to memorize the results of learning, and have a higher learning speed. This paper describes the nest-structuring of learning areas which, unlike conventional air-fuel ratio learning, realize both faster learning and improvements in the compensating accuracy by subdividing the learning area.

Through the rapid evolution of microcomputer capability in the field of automotive electronic fuel injection, a system has recently been developed to integrate powertrain control, unifying engine control and automatic transmission control. Implementation of advanced control theory is one of the major issues in this field and will benefit greatly from microcomputer performance improvements. This paper commences with a discussion of the trend toward higher performance requirements in integrated powertrain control, driven by a new concept in control: variable transmission shiftpoint control based on vehicle operating conditions. The latter portion of the paper describes a new 16-bit dual CPU system for integrated powertrain control. The system achieves an improvement in processing through high-density communication.

Electronic fuel injection systems for automotive engine control are now capable of greater control precision and increased function through the progress in microcomputer performance and cost efficiency. The dependence of engine control systems on microcomputer performance is expected to remain significant for the future as well, in such areas as improved learning control techniques and new control theories. This paper first refers to sequential fuel injection systems under cylinder-by-cylinder control and adaptive learning control techniques for which a new control theory has been employed, and then presents a new microcomputer integrated with a multifunctional timer module for extremely high real-time control capabilities by means of its 16-bit core CPU. A single chip ASIC memory unit integrated with EPROM and RAM devices serves as a peripheral LSI for the microcomputer

Air-fuel ratio learning control has generally been adopted in automobile engines at present. For this control, it is important that learning at a high speed be minutely performed to cope with a driving state which may vary considerably at high speed. This report describes a process for attaining this objective, in which regular learning, having a high learning detection precision, and presumptive learning for the transient region and the region where air-fuel ratio feedback is not affected are performed at a high speed while monitoring the progress of such learning.