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The gasoline engine with continuously variable valve actuation is recently focused on as a method to improve fuel consumption and performance of a vehicle. The suction air amount is controlled without using throttling, and therefore can dramatically reduce pumping losses. On the other hand, the suction air amount is significantly affected when the valve lift is slightly changed under low lift condition. In other words, the response of the suction air amount against the change of the valve lift is very sensitive. Furthermore, a conventional gasoline engine with a throttle has a self-stabilizing effect on engine speed, but an engine controlled by a valve lift is not. Therefore, accurate idle speed control is required in order to reduce engine idle speed and improve fuel consumption. The conventional control is composed of a two-degree-of-freedom sliding mode controller and an adaptive disturbance observer.

A continuously variable valve lift gasoline engine can improve fuel consumption by reducing pumping loss and increase maximum torque by optimizing valve lift and cam phase according to engine speed. In this research, a new control system to simultaneously ensure good driveability and low emissions was developed for this low fuel consumption, high power engine. New suction air management through a master-slave control made it possible to achieve low fuel consumption and good driveability. To regulate the idle speed, a new controller featuring a two-degree-of-freedom sliding-mode algorithm with cooperative control was designed. This controller can improve the stability of idle speed and achieve the idle operation with a lower engine speed. To reduce emissions during cold start condition, an ignition timing control was developed that combine I-P control with a sliding mode control algorithm.

Engines equipped with continuously variable valve lift (CVTL) system can improve the fuel consumption of gasoline engines and provide better torque and power characteristics than conventional engines using variable cam phasing or switcthable valve timing and lift mechanisms. However, the relationship between the intake valve lift and suction air volume to the cylinders changes drastically at low valve lift and low engine speed conditions. This causes air-fuel ratios between cylinders to differ and deteriorates control performance of the airfuel ratio during transient operations. These in turn reduce the catalyst conversion rate. The purpose of this research is aimed at improving the control performance of the air-fuel ratio with a redesigned secondary O2 feedback system using a delta-sigma modulation algorithm and a feed-forward compensation algorithm for suction air volume.

An accurate and rapid engine speed control has been required to improve the shift quality of automated manual transmissions. However, conventional controls could not provide sufficient controllability. They caused the overshoot and steady-state error of engine speed from target values. Therefore, a two-degree-of-freedom sliding mode algorithm was newly designed and applied to the engine speed control. This algorithm can independently assign the disturbance suppression characteristic and tracking performance, and has excellent robustness against the changes in engine dynamics. As a result, the overshoot and steady-state error were prevented under all engine conditions.

The sliding mode algorithm is used for air fuel ratio control, device control, and other systems because of its high responsiveness and robustness. A special feature is that the disturbance suppression characteristic can be set as needed by changing the gradient of the switching line. However, there has been no research into applying this feature. Taking note of the fact that a servo system with a high compliance can be established by lowering the disturbance suppression characteristic, this algorithm was applied to gearing control in automated manual transmissions. During gear changes, automated manual transmissions require the positioning control of a shift rod, the contact control of a sleeve and synchronizer ring, and revolution synchronizing control of the main shaft and counter-shaft by pressing in the sleeve.

Electronic throttle control has been receiving increased attention lately as a technique for attaining highly accurate idling air control and improving emissions. To accomplish these goals, it is necessary to achieve greater robustness in control performance, and to compensate for the production variability of individual units and degradation of parts over time. Up to now, it has been difficult for PID control systems to recognize uncertain disturbances, and this has been an impediment to achieving balance between robustness and responsiveness. To attain robustness, an adaptive control system has been constructed which utilizes sliding mode control and includes an identifier to perform sequential calculations. This technology has realized previously unattainable levels of robustness, accuracy, and responsiveness in an electronic throttle control system.

The Honda Accord is the world's first automobile meeting the SULEV category criteria in the LEV-II exhaust emissions standards. An improved accuracy engine control system and catalyst account for the automobile's extremely low emissions. The accuracy engine control system includes double adaptive air-fuel ratio feedback loops composed of STR (Self-Tuning Regulator), for primary air-fuel ratio control, and PRISM (Prediction and Identification Sliding Mode Control), for secondary O2 feedback. The basic algorithm of the latter was presented at SAE 20001). However, two issues required further PRISM algorithm improvements in order to apply the double adaptive loops to an actual vehicle. One such achievement is both the compensation for engine dynamic characteristics by PRISM and the avoidance of the reciprocal interference with two adaptive loops.

Recently, much research has been carried out on secondary O2 feedback which performs control based on the output from a secondary O2 sensor (HEGO sensor). In this research it has been found that, regardless of catalyst aging conditions, the HEGO sensor output indicates 0.6 V when the catalyst reduction rate is maintained at the optimum level. Therefore, based on this relationship, we designed an accurate secondary O2 feedback with the aim of reducing emissions by stabilizing the HEGO sensor output to 0.6 V. In order to realize this control, it was necessary to solve the three problems of nonlinear catalyst characteristics, dead time characteristics, and changes in dynamic characteristics due to catalyst aging conditions. Therefore, these problems were solved using the modeling approach of robust control and a new robust adaptive control named Prediction and Identification Type Sliding Mode Control.

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.

HONDA has developed technology to fulfill the strictest emissions standards to date. That is, we have developed the technology necessary to satisfy the state of California's SULEV (LEV–II) regulations. We were able to move from the conventional 600–cell, 4.3mil three–way catalyst to a 1200–cell, 2.0mil catalyst through the application of new canning technology. We were also able to achieve early catalyst light–off and improved conversion performance without increasing the precious metal content. However, it was not possible to satisfy the SULEV standards using only these improvements to the catalyst. It was also necessary for us to develop new emission control technology for the various stages of engine operation: cold, warm–up and post warm–up. Specifically, we developed technology that dramatically increases catalyst light–off speed by controlling intake air and ignition timing.