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Fuel economy can be improved by adopting the method of lean burning and reducing idle speed. And to achieve it, it is required to improve the performance of idle speed control. The dead time in the process of intake air control is one of the reasons, which cause the worse response and poor stability of idle speed control. The problem of the dead time compensation for intake air control is investigated in this paper. The Smith predictor and various linear compensators are discussed in it. By using a proper compensator, it is possible to improve the performance of the system's disturbance rejection. A new compensation method is presented in this paper, which is adopting a Smith predictor combining with disturbance compensator M1(s) and M2(s), to improve the idle speed control system's response to the disturbance at the front or rear part of the dead time.

Meeting future exhaust emission and fuel consumption standards for passenger cars will require refinements in how the combustion process is carried out in spark ignition engines. A direct injection system reduces fuel consumption under road load cruising conditions, and stratified charge of the air-fuel mixture is particularly effective for lean combustion. This paper describes an approach to improve combustion stability for direct fuel injection gasoline engines. Effects of spray characteristics (spray pattern and diameter) and air flow motion on the combustion stability were investigated. Spray patterns were observed by the laser sheet scattering method and 3-dimensional laser doppler velocimetry. Mixture behavior in the combustion chamber was observed by the laser-induced fluorescence method using an excimer laser and single cylinder optical engine. It was found that the spray pattern for a pressurized condition affects the combustion stability and smoke generation.

Mixture formation technology for a fuel injection system has been investigated. The effects of spray droplet diameter on engine performance were clarified. The combustion light Intensity was measured with a spark plug integrated combustion flame sensor. When sequential injection is used for better responsiveness in fuel injection systems, engine performance may be reduced through increased HC emissions. Reducing the diameter of the spray droplets and preventing fuel from adhering to the intake manifold walls promote vaporization, reduce fuel concentration on the cylinder wall, decrease HC emissions, improve cold start ability, and give good idling performance.

High engine load and over-heated engine cylinder are the main causes of engine knock. When knock occurs in an engine, vibrations composed of several specific resonant frequencies occur. Some of these resonant frequencies are missed stochastically because specific resonant frequencies are caused by different resonant vibration modes in an engine cylinder. However, a conventional knock detector can only measure a fixed resonant frequency using a band-pass filter. This paper presents a multi-spectrum method which greatly improves knock detection accuracy by detecting the knock resonance frequencies from several specific vibration frequencies. Through overcoming the random occurrences of knock resonant frequencies by selecting specific frequencies, knock detection accuracy can be greatly improved. We studied a high precision knock detection method using real-time frequency analysis and a piezoelectric accelerometer on a V-6 engine.

An automatic matching method for engine control parameters is described which can aid efficient development of new engine control systems. In a spark-ignition engine, fuel is fed to a cylinder in proportion to the air mass induced in the cylinder. Air flow meter characteristics and fuel injector characteristics govern fuel control. The control parameters in the electronic controller should be tuned to the physical characteristics of the air flow meter and the fuel injectors during driving. Conventional development of the engine control system requires a lot of experiments for control parameter matching. The new matching method utilizes the deviation of feedback coefficients for stoichiometric combustion. The feedback coefficient reflects errors in control parameters of the air flow meter and fuel injectors. The relationship between the feedback coefficients and control parameters has been derived to provide a way to tune control parameters to their physical characteristics.

This paper discusses causes and the mechanism of surging, back and forth chassis oscillation which occurs in cars with electronically controlled multi-point gasoline injection systems. This occurs during sharp acceleration, engine braking deceleration, and low speed coasting, at rather low ratio gear positions. We conclude that the mechanism of surging is parametric coupled oscillation. This conclusion is based on experimental data analysts and parameter sensitivity analysis using a chassis and engine dynamics simulator. The elements of parametric coupled oscillation are: a forcing system composed of engine control systems, engine and power transmission systems; a resonance system composed of axle and frame-body translation systems; a feedback system composed of axle translation systems and wheel revolution systems.

A new air-fuel ratio control algorithm and its effect on automotive engine operation is described. The system consists of a wide range air-fuel ratio sensor and a single point injector with an ultrasonic fuel atomizer. The air-fuel ratio control adopts PID control and it has built-in learning control. A 16 bit microcomputer is used for the latter. The results of three studies are given. The first deals with adaptive PID gain control for various conditions. The second is the new learning control which uses an integration terra. The third is individual cylinder air-fuel ratio control.