A 2-stroke gasoline engine may have an opportunity as a high efficiency engine in series hybrid with avoiding the low-load operation. Therefore, for the 2-stroke opposed piston engine that uses both SI operation and HCCI operation, we optimized the parameters that maximize the thermal efficiency using 1D-CFD and optimization software. Since the miller cycle is realized by using the EX crank delay and the dynamic effect of exhaust, knocking can be avoided even with a very high volume ratio (geometric compression ratio). Combined with the low cooling loss of the opposed piston engine, high thermal efficiency may be realized.
To achieve variable compression ratio, the multi-link system which has secondary merit as silence performance and low friction loss was selected. The multi-link system has the lever system which can amplify not only the load but also piston stroke. By using this characteristic, the main bearing load capacity was improved by the high rigidity crankshaft in spite of the amplified load. Simultaneously, by the arrangement of control shaft which is unique parts of multi-link system, the torque fluctuation was reduced. As a result, the size of multi-link system or engine was designed compactly.
We predicted the oil behavior around the piston ring in an automobile engine based on gas-liquid two-phase flow analysis and investigated the mechanism of oil consumption. The calculation results quantitatively revealed the pressure and the flow rate at various positions around the ring. The inflow oil increases the pressure at the bottom of the side rails and flows into the groove through the side clearance. The results are not affected by the grid size even when the inflow oil film thickness from the skirt is thin due to the level set method, which resolves the interface sharply. The maximum oil film thickness is similar to the case where the oil velocity is the maximum by inertia force due to increased oil volume.
The authors were studying micro groove bearing using the copper-lead alloy that was used at the time of development, so report the results of the study. Ｗear test on engine test bench reveals optimal ratio of width to groove depth for micro groove bearing. The friction loss torque of properly designed micro groove bearings is slightly reduced compared to natural plain bearings. Authors thought that the upper limit of oil clearance could be reduced by that amount. Properly designed micro groove bearing endurance test showed no seizure or fatigue, and good wear results were obtained. The optimum groove size for micro groove bearings are groove depth of 2.5-4.5μｍ and groove width of 0.15-0.25mm.
In this study, we developed a technology that can detect multi-hydrocarbon component in a wide range of 100nm with 3μm high-speed scanning laser system based on difference frequency generation method lasers and tunable diode laser absorption spectroscopy (TDLAS). The applicability of simultaneous multi-hydrocarbon components measurement technology in the engine process was evaluated. TDLAS with 3μm high-speed scanning laser system is capable of mixture measuring and has the potential for practical application.
The knocking phenomenon at the time of auto-ignition can be examined in detail using the pressure transport equation. In particular, it has been clarified that the expansion effect suppresses the pressure increasing. In this study, effective applications of the expansion effect based on the acoustic energy equation derived from transport equations is discussed. And the knock suppression theory is verified using numerical simulations and the results show that knock intensity can be reduced. Finally, it is shown that the knock intensity has a similarity rule to acoustic Damkohler Number.
In this study, the compact PAH growth model previously presented by authors was combined with a reduced gas-phase reaction model for toluene reference fuel and ethanol proposed by Sakai and Miyoshi. The present model, PS3SMr2, consists of 107 chemical species and 473 elemental reactions. This model well reproduces the ignition delay time and the laminar flame speed of iso-octane, n-heptane, toluene and ethanol air mixtures as well as the base model. Verifications of soot formation characteristics were first performed for the experimental results for a gasoline surrogate fuel measured by shock tube. As a result, it was shown that the model can well reproduce sooting characteristics regardless of the pressure and the amount of oxygen. The ethanol blend effect to the test fuel on the soot emissions was verified on the simulated in-cylinder pool combustion experiments for iso-octane/toluene/ethanol blended fuels. As a result, we showed that the present model shows a good reproducibility of the qualitative trend of soot emissions with the change in the equivalence ratio for a gasoline surrogate fuel as well as existing model results. As for the effect of ethanol blend, it was shown that the experiments were well reproduced when toluene was replaced and that there was room for improvement when iso-octane was substituted.
In this study, we considered a method for clarifying main factors increasing vehicle interior noise using operational transfer path analysis (TPA) principal component model (PCCA: principal component contribution analysis). Through an experiment using simple vehicle physical scale model at an operational condition, the main factors (acoustic resonance in cabin, vibration resonance of body or vibration resonance of flame) were estimated by evaluating the elements of repeated PCCA results and the verification was carried out through the countermeasure for the reduction of the interior noise.
It is necessary to consider driver’s behavioral change in an integrated method to detect abnormal physical condition while driving because various symptoms occur due to the disease. In this paper, we analyzed the characteristics of gaze behavior with respect to driving scenery for higher brain dysfunction, and clarified differences in gaze behavior between attention-impaired patients and controls. In addition, we evaluated the robustness of the method of detecting abnormal signs from gaze behavior in actual vehicles and environments.
An available path planning is required for a vehicle turning control to pass through any target point. It is well known that a vehicle driving trajectory is well coincided with a clothoid curve when the steering wheel was turned with constant speed. However, a real-time planning without trial and error of a clothoid curve that pass through the target point has not been much reported. This paper investigated a real-time path planning using the characteristics of both a clothoid curve and turning trajectory. The experimental results showed that the vehicle well passed through any target point.