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Technical Paper

Development of New AMT Shift Speed Control System for Lexus LFA

2011-10-06
2011-28-0103
The development of the Lexus LFA focused on the pursuit of a passionate driving experience suitable for a super sports car. The shift speed control system in the LFA is an automated manual transmission (AMT) that uses an electrohydraulic actuator. The excellent shifting performance of the AMT was achieved by developing control technology that performs smooth, quick, and highly responsive shifting in accordance with the driving conditions. This was the result of repeated evaluations in both normal driving and on circuits featuring many acceleration, deceleration, and high-speed driving sectors. This paper describes the AMT shift speed control system and technology.
Technical Paper

Development of an On-Board Type Oil Deterioration Sensor

1993-10-01
932840
According to the principle of pH measurement, an on-board type engine oil deterioration sensor has been developed. The developed sensor is composed of a Pb and oxidized stainless steel electrodes. The sensor signal shows a good linear relationship to the quasi-pH value of the oil. Especially in the region where the oil deterioration proceeds, the remaining basic additives in the oil is easily estimated from the sensor signal.
Technical Paper

Analysis of Poor Engine Response Caused by MTBE-Blended Gasoline from the Standpoint of Fuel Evaporation

1992-02-01
920800
Fifty percent distillation temperature (T50) can be used as a warm-up driveability indicator for a hydrocarbon-type gasoline. MTBE-blended gasoline, however, provides poorer driveability than a hydrocarbon-type gasoline with the same T50. The purposes of this paper are to examine the reason for poor engine driveability caused by MTBE-blended gasolines, and to propose a new driveability indicator for gasolines including MTBE-blended gasolines. The static and dynamic evaporation characteristics of MTBE-blended gasolines such as the evaporation rate and the behavior of each component during evaporation were analyzed mainly by using Gas Chromatography/Mass Spectrometry. The results of the analysis show that the MTBE concentration in the vapor, evaporated at ambient temperature (e.g. 24°C), is higher than that in the original gasoline. Accordingly, the fuel vapor with enriched MTBE flows into the combustion chamber of an engine just after the throttle valve is opened.
Technical Paper

Analysis of Oil Consumption by Observing Oil Behavior Around Piston Ring Using a Glass Cylinder Engine

1989-09-01
892107
The reduction of engine oil consumption rate is one of the important concerns for automotive engineers. However, it has been difficult to solve this subject, since the oil consumption mechanism has not yet been elucidated. In this study, to clarify the oil loss mechanism via the piston rings, a transparent glass cylinder engine was used to observe oil behavior between cylinder wall and piston surface. For photographic observation, a high speed camera, a still camera. and a TV camera were used. Since the new photographic system by using TV camera with a synchro - flash and a synchro-memory was applied, it was also possible to observe the oil behavior in detail. Moreover, a new visual method by which colored oil was injected from the various points on the piston surface and traced was developed for easy analysis of oil movement around the piston ring.
Technical Paper

Study of Transient Oil Consumption of Automotive Engine

1989-09-01
892110
The oil consumption phenomena during transient engine operating condition is analyzed. The investigation of the oil consumption by means of the real-time oil consumption meter shows that higher intake manifold vacuum during engine-brake condition causes a larger amount of transient oil consumption. The reverse blowby gas flow into the combustion chamber from the crankcase is generated by the high vacuum under engine-brake condition. It is found that this reverse gas flow carries the oil into the chamber from the third land of the piston through the ring end gap of the compression rings. The oil on the piston skirt leaks into the third land through the clearance between the oil ring and the cylinder bore. The weakened bore-to-ring contact pressure by the piston slap motion increases the amount of the leakage oil. New ring sets and pistons are developed based on the results of this study.
Technical Paper

Investigation of the Transient Oil Consumption of Engine by the Newly Developed Oil Consumption Meter

1986-02-01
860544
A new method of continuous measurement of engine oil consumption using sulfur as the tracer has been developed. The modified non-dispersive-infrared (NDIR) analyzer with the SO2 absorbent and a permeable plastic type dryer enable to measure very low concentration of SO2 in the exhaust gas. By the use of this method, the engine oil consumption under the transient engine operating condition has been analyzed. The experimental result show that the measured value of the transient oil consumption is larger than the estimated value by the quasisteady method using the experimental data of steady-state operations. The difference between these value is explained by the simple model developed here. This model also show that the total oil consumption under the transient engine operating condition depends mainly on the amount of oil drawn into the combustion chamber by the high vacuum during engine-brake conditions.
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