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An active suspension system controls a spring constant and an attenuater in real time using a power supply. Generally, the hydraulic pressures are used for transmitting the power. Therefore, a highly reliable and inexpensive control system has been required for a commercial use. This has been achieved by developing a mechanical fluid servo valve which comprises a simple combination of a solenoid valve and a spool valve. The technical problem of the valve vibrations has been solved through the numerical analyses, the fluid flow visualization tests and the vehicle tests.

This paper describes the investigation into the contact pressure and incidental deformation on the contact surface of the piston skirt which comes in contact with the cylinder bore in operation. Focused on the single piston static tests in the first place, relationship between the contact pressure on said skirt and the strains developed inside the skirt, and the relationship between the deformation of skirt face and the strains inside the skirt were studied. Then, the dynamic contact pressure onto the skirt in operation and the amount of deformation were calculated based on the relationships mentioned above using the factor of dynamic strains measured on an engine in operation. The deformation of skirt calculated using said dynamic strains was verified by the direct measurement of the skirt deformation. It was demonstrated that the thrust side of a piston skirt was largely deformed due to enlarged contact pressure caused by the piston slap subsequent to firing top dead center.

This paper reports that estimation accuracy of suspension stroke velocity is increased by considering the damping force delay characteristics to an observer. Thereby ride comfort is improved, using the simple and low-cost semi active suspension systems that use only three vertical acceleration sensors.

This paper reports the results of a study into a preview control that uses the displacement of the road surface in front of the vehicle to improve for front and rear actuator responsiveness delays, as well as delays due to calculation, communication, and the like. This study also examined the effect of a preview control using the eActive3 electric active suspension system, which is capable of controlling the roll, pitch, and warp modes of vehicle motion.

In this paper, we discuss vehicle directional stability and introduce advanced stability control (ASTC) to stabilize the vehicle during severe cornering. Vehicle behavior in a transient steering condition during severe cornering was analyzed by computer simulation. It was found that applying an external yaw moment makes the vehicle more stable. The effect of controlling the brake force response is also evaluated by simulation to determine the brake actuator response criteria. The actual vehicle test was performed with a pylon slalom using a hydraulic brake actuator. It is verified that the ASTC stabilizes the vehicle for transient steering maneuvers.

It is well known that the self-aligning torque decreases before lateral force is saturated. Focusing on this self-aligning torque change, an estimation method has been developed to detect the friction condition between steered wheels and road surface before the lateral force reaches the friction limit. The lateral grip margin (LGM) is defined based on the self-aligning torque change, which is obtained using the EPS torque and motor current information. The LGM is theoretically analyzed based on the tire model and experimentally verified through the full-scale vehicle test. Moreover, the estimated LGM is applied for the chassis control systems to improve the vehicle dynamics performance.

There are such outside door handles called smart handles which have a transmitting antenna, a lock/unlock sensor, and a sensor detection circuit, with which operation of door lock is possible just by "touching" the electrostatic-capacitance type sensor of the handles.As the design of the outside handles, body color painting and Cr plating are adopted. However, if plating is applied over the entire surface of a smart handle, electromagnetic waves transmitted from the antenna will be blocked since plating material is electrically conductive. In addition to this, touching a part other than the sensor may change the electrostatic-capacitance of the sensor, which results in unwanted functioning of the lock/unlock sensor. Because of this, only part of the handle, which does not hinder the transmission of electromagnetic waves and does not cause unwanted functioning, is covered by plating, that is called, "Partially plated specifications" (Figure 1).

A new variable displacement pump has been developed. This pump can variably change its discharged flow rate in accordance with the revolution changes of an automotive engine from idling engine speed to 6000rpm. It can quickly discharge oil necessary for controlling the autmotive active suspension system. This pump is of a swash plate, axial piston type which controls optimal fluid flow in time by using a pressure sensing control valve. Further, in order to improve the quietness in the vehicle system, the pulsation of the pump pressure was reduced and this pump's utility was realized for automobile use. This is a report on how the pump was introduced for commercial automobile use.

Drive train components (transmission, differential gears, etc.) can be made smaller and lighter if the excessive torque exerted on them can be reduced during the quick start of a vehicle. An orifice put in the hydraulic clutch piping path is an effective method. However, increased oil viscosity at low temperatures (0°C or below) makes the “pedal feel” worse. In order to increase the orifice diameter for better “pedal feel”, a shape memory alloy spring, for operation at low temperatures, was developed by adding cobalt to the nickel-titanium alloy. Consequently, a Variable-Orifice valve, using the shape memory alloy spring, is practical.

As a process that enables the high-speed and continuous forming of lengthy materials with a constant cross-sectional configuration, roll forming offers much higher productivity than the stamping process. However, in case a change must be made to the shape of the cross section, the material must normally be stamped or joined with a part containing a separate shape. This affects productivity, increases the number of pieces, and degrades the material's appearance. This report describes the roll-forming technology that we developed, in which the cross section of the material can be changed gradually. This method adopts a system which uses a movable and rotatable roll-stand that enables high-speed, continuous roll-forming processes.

AISIN SEIKI CO., Ltd. Started the production of electronically controlled hydraulic automatic transmissions for medium-duty trucks and buses in 1989. The number of vehicles on the Japanese market in which this system is adopted is increasing steadily. After re-examining market needs, AISIN SEIKI CO., Ltd. has newly developed an electronically controlled hydraulic automatic transmission A580 which focuses on improved input capacity, driving performance and fuel economy for medium-duty trucks and buses and lessens learnt from experience.