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A fuel injector adapter which can divide the fuel spray into two streams and produce fine fuel atomization is being developed to improve fuel economy and transient performance in four-valve gasoline engines. The adapter has the shape of a pair of spectacles and is attached to the orifice outlet of the injector. The optimum shape of the adaptor is investigated by 3-D viscous flow analysis by FEM and experiment. A 17% improvement in transient performance over the conventional Hitachi injector is confirmed by engine tests in a passenger car.

Chassis back and forth oscillation caused by sudden engine torque increase tends to occur, according to the characteristic of vehicle dynamics. This oscillation is called an acceleration surge and gives a vehicle driver a feeling of discomfort. This paper provides two control methods which can change the characteristic of vehicle acceleration response in order to suppress acceleration surge and to macth with driver's preference. The first control method is an acceleration servo method which is composed of control reference model and ignition timing control. The second control method is a variable response characteristic control algorithm. We treat the controlled object as the second order model with time delay, and assign the characteristic roots of transfer function in order to obtain the desired response.

Attenuation of fore and after vehicle vibration caused by transient throttle pedal maneuvering is a key factor in achieving a good drivability. The dynamics of this vibration is analyzed considering torque generated by combustion as the exciting force. The relationship between vibration attenuation and improvement of drivability is determined using a subjective, low frequency vibration test. Through these analyses and tests, a new vibration control system is developed which controls the above noted torque by providing optimum adjustment of ignition timing. Decreasing fore and after vehicle vibration without adversely affecting vehicle performance, this control system improves drivability in both FF and FR cars by more than 1.0 evaluation point.

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.