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This paper discusses the development of a system enabling real-time measurements of combustion pressure in an internal combustion engine, using a comparatively low-cost polycrystalline piezoelectric element. Tests conducted using a mass production vehicle showed that by using the measured cylinder pressure, the status of combustion could be measured across the entire range of driving conditions, enabling accurate detection of misfires and knocking. To date, despite their comparatively low cost, the use of piezoelectric elements in mass production vehicles has represented a challenge, because the temperature characteristics of the elements in the use environment, age degradation, and other factors may cause variations in output. This research therefore studied the variation in sensor output in terms of each causal factor.

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.

In a conventional fuel metering control system (speed density method) for an internal combustion engine, the fuel injection amount during transient operation is usually determined by using mapped data and various settings in a feedforward system predetermined through experimentation. However, this still does not necessarily represent the ideal level of compensation under a diverse range of environmental conditions. In order to satisfy various demanding requirements, such as reducing emissions, it is vital that the controllability of the air excess ratio(λ) be enhanced. The main technological obstacle that needs to be overcome is how best to determine accurately the required fuel amount from the engine in the feedforward system. To enable accurate prediction of the cylinder intake air volume, physical formulas of fluid dynamics were used to facilitate formulation of a model for the dynamic behavior of the intake air.

The purpose of this paper is to quantify the improvements possible for ULEV emissions by improved air-fuel ratio control during starting by modifying conventional fuel injection strategy with a first order wall-wetting-fuel model. Measurements of emissions during first 30 starting cycles of a ULEV engine, made with a fast response flame ionization detector (FID) and conventional fuel injection strategy, show that these account for 17% of the overall FTP-75 mode HC emissions. The wall-wetting-fuel model is a two coefficient model: α, the ratio of the injected fuel mass to the fuel mass inducted into the cylinder during a given cycle, and β, the ratio of the total fuel mass accumulated on the intake port wall to the mass inducted into the cylinder from the accumulated fuel at a given cycle.

In this research project, modeling of the dynamic air excess ratio (λ) behavior in the exhaust gas at the confluence point in the exhaust manifold was performed. By applying an observer which is one method described by modern control system theory, estimation of the λ for each cylinder was carried out using one λ sensor. The estimated value was used to perform λ feedback control for each cylinder, allowing compensation of deviation in air-fuel ratio between cylinders and individual control of fuel injection volume for each cylinder, dramatically enhancing λ controllability.

The reduction of fuel consumption is of great importance to automobile manufacturers. As a prospective means to achieve fuel economy, lean burn is being investigated at various research organizations and automobile manufacturers and a number of studies on lean-burn technology have been reported to this date. This paper describes the development of a four-valve lean-burn engine; especially the improvement of the combustion, the development of an engine management system, and the achievement of vehicle test results. Major themes discussed in this paper are (1) the improvement of brake-specific fuel consumption under partial load conditions and the achievement of high output power by adopting an optimized swirl ratio and a variable-swirl system with a specially designed variable valve timing and lift mechanism, (2) the development of an air-fuel ratio control system, (3) the improvement of fuel economy as a vehicle and (4) an approach to satisfy the NOx emission standard.