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As a part of our efforts to conform to particulate emission regulation in the U.S., a particulate trap system has been developed that collects particulates using a filter and burns them by heat of the exhaust gas. In order to more easily burn the particulates, the system combines a platinum catalyst to lower the ignition temperature of particulates and a mechanism which causes the exhaust gas to bypass the filter during non-injection periods, thereby preventing a temperature drop of the filter. In the various driving tests conducted, including urban areas, almost no particulate deposits were found on the filter. This simplified particulate trap system is outlined in this paper.

A new system developed by the authors to predict the cavitation erosion of the fuel injection system utilizes ultrasonic wave issued by collapse of cavities in the system. This prediction system can replace the conventional time-consuming endurance test and thus greatly contributes to the saving of cost and time. The technical features of this system include: (1) Detection of ultrasonic wave through the fuel injection pipe wall using a piezoelectric sensor, with the ultrasonic wave signal intensity in a higher frequency range increasing with the cavitation intensity, i.e., the leval of energy released by the collapse of cavities; (2) the system output representing effective cavitation intensity which is given after being processed from the raw state in a high pass filter; and (3) capability of dealing with a higher level of accuracy than by the conventional method.