Search Results

Furuhama(1)* proposed the new two ring package consist of a pressure ring and a narrow single-rail oil ring (NSOR) in 1985. Number of studies(2) have been done for the purpose of reducing the oil consumption (OC) in this ring package. However, OC reduction problem has been still remaining to solve as only one serious problem of this ring package. The reasons of a larger OC in the new ring package than the conventional three ring has been hardly understood, considering the OC control ability on second ring in three ring package will not so large since the fact that the oil film thickness is thicker than that of the oil ring. In this study, the mechanism of OC increase in new ring package was found out at last, as a result, OC of new ring package piston was improved up to the same level of conventional three ring package piston.

Exhaust-gas recirculation (EGR) causes the piston rings and cylinder liners of a Diesel engine to suffer abnormal wear on the sliding parts. The present study aimed at making clear such abnormal wear structurally by examining the state of lubrication of the piston with a floating liner method, observing directly a visualized cylinder and experimenting on a Diesel engine for wear. As a result, it was confirmed that soot in EGR gas would change a lot the characteristics of the piston friction force. There are two mechanisms: one directly enters the sliding surfaces, and the other enters the ring rear, applying more load to them. It was also confirmed that the level of wear on the piston ring would vary to a large extent as the state of lubrication changed.

This study has been conducted aiming at an experimental verification of the ring collapse phenomena that occurs in a taper faced second ring of a direct fuel injection type truck diesel engine. The oil film thickness of the second ring, the ring axial motion and the inter-ring pressure have been measured under various operating conditions of engine. As a result, it is verified that the back pressure of the second ring becomes lower than the second land pressure, and that the second ring oil film becomes extremely thick temporarily where the second ring contacts with the ring groove upper surface. It is also verified that blow-by passes through the second ring where the oil film of the second ring becomes thick. Hence it is highly probable that the collapse of the second ring has occurred at that time.

Ammonia is one of the most useful compounds that react with NOx selectively on a catalyst, such as V2O5-TiO2, under oxygen containing exhaust gas. However ammonia cannot be stored because of its toxicity for the small power generator in populated areas or for the diesel vehicles. A new concept for NOx reduction in diesel engine using ammonia is introduced. This system is constructed from the hydrogen generator by fuel reformer, the ammonia synthesizer, SCR catalyst for NOx reduction and the gas injection system of reformed gas into the cylinder. Experimental results show that, the SCR catalyst provides a very high rate of NOx reduction, reformed gas injection into cylinder is very effective for particulate reduction. WHEN CONSIDERING INTERNAL COMBUSTION ENGINES of the 1990's the question of how to harmonize the engine with the natural environments is one of the greatest problems. The internal combustion engine changes a substance into energy via its explosive combustion.

The objective was to rank piston friction and noise for three piston architectures at three cold clearance conditions. Piston secondary motion was measured using four gap sensors mounted on each piston skirt to better understand the friction and noise results. One noticeable difference in friction performance from conventional designs was as engine speed increased the friction force during the expansion stroke decreased. This was accompanied by relatively small increases in friction force during the other strokes so Friction Mean Effective Pressure (FMEP) for the whole cycle was reduced. Taguchi's Design of Experiment method was used to analyze the variances in friction and noise.

Proposed at Musashi I.T. Engine research Laboratory in order to realize a smaller size and lower friction piston was a new piston ring parkage, which consisted of one pressure ring and one narrow single-rail oil ring. The new package has tested for two different types of gasoline engines to examine its influences on blow-by, piston temperature, piston friction and oil consumption. Efforts have been also made to improve these characteristics of the package and have resulted in its promising prospects.

Exhaust-gas recirculation (EGR) causes the piston ring and cylinder liners of a diesel engine to suffer abnormal wear. The present study aimed at making clear the mechanism of wear which is induced by soot in the EGR gas. The piston ring has been chrome plated and the cylinder was made of boron steadite cast iron. Detailed observations of the ring sliding surfaces and that of the wear debris contained in lubricating oil were carried out. As a result, it was found that the wear of the top ring sliding surfaces identify abrasive wear without respect to the presence of EGR by steadite on the cylinder liner sliding surface. In addition, it is confirmed in a cutting test that soot mixed lubricating oil improved in performance as cutting oil. Based on these results, we proposed the hypothesis in the present study that ring wear is accelerated at EGR because abrasive wear increases due to a lot of soot mixed into lubricating oil improving the performance of lubricating oil as cutting oil.