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The Wankel rotary engine is more compact than conventional piston engines, but its oil and fuel consumption must be reduced to satisfy emission standards and customer expectations. A key step toward this goal is to develop a better understanding of the apex seal lubrication to reduce oil injection while reducing friction and maintaining adequate wear. This paper presents an apex seal dynamics model capable of estimating relative wear and predicting friction, by modeling the gas and oil flows at the seal interfaces with the rotor housing and groove flanks. Model predictions show that a thin oil film can reduce wear and friction, but to a limited extent as the apex seal running face profile is sharp due to the engine kinematics.

The objective of the present study is to analyze soot formation in diesel engine combustion by using multi-dimensional combustion simulations with a parallelized explicit ODE solver. Parallelized CHEMEQ2 was used to perform detailed chemical kinetics in KIVA-4 code. CHEMEQ2 is an explicit stiff ODE solver developed by Mott et al. which is known to be faster than traditional implicit ODE solvers, e.g., DVODE. In the present study, about eight times faster computation was achieved with CHEMEQ2 compared to DVODE when using a single thread. Further, by parallelizing CHEMEQ2 using OpenMP, the simulations could be run not only on calculation servers but also on desktop machines. The computation time decreases with the number of threads used. The parallelized CHEMEQ2 enabled combustion and emission characteristics, including detailed soot formation processes, to be predicted using KIVA-4 code with detailed chemical kinetics without the need for reducing the reaction mechanism.

A high compression ratio is an effective means for improving the thermal efficiency of an internal combustion engines. However, a high compression ratio leads to a rapid rise in the combustion pressure, as it causes a high impulse force. The impulse force generates vibrations and noise by spreading in the engine. Therefore, reducing the vibration of the combustion (which increases as the compression ratio increases) can improve the thermal efficiency while using the same technology. We are conducting model-based research on technologies for reducing combustion vibration by applying a granular damper to a piston. To efficiently reduce the vibration, we suppress it directly with the piston, i.e., the source of the vibration. Thus, the damping effect is maximized within a minimized countermeasure range.

A structure which effectively improves compatibility in a vehicle-to-vehicle frontal impact has been considered focusing on sub-frame structure that disperses applied force with multiple load paths. Evolved sub-frame structure has been studied by CAE with RADIOSS to search the possibility to reduce aggressivity and to improve self-protection at the same time. Vehicle models used for this compatibility study were a large saloon car with sub-frame and a small family car without sub-frame. The large saloon car had three different front structures: original, forward-extended sub-frame, and original with 25%-stiffness reduced structures. The types of collision contained four different crash modes in a combination of lateral overlap rate difference and side member height difference.

Valve train motion was investigated with computer simulation technique. The application of a 5-mass model was found to accurately predict the valve train behavior. It was identified that valve train stiffness and close-side characteristics of valve lift curve have significant effects on bounce occurrence. A valve train with high stiffness tends to develop bounce after jump, while on one with low stiffness, bounce starts in the absence of jump. These findings allowed to develop a new cam form with use of harmonic curves for elevating the revolution limit of the valve train.

To realize high levels of handling, driving performance, and NVH characteristics for a sports car, it is important to develop a lightweight and high-stiffness vehicle body. For the new RX-7, weight saving and higher stiffness were pursued as top priorities from the very first stage of the program. We were able to achieve 20% higher bending stiffness and 15% higher torsional stiffness with vehicle weight reduced by 30 kg, compared with the former model. The development of the lightweight, high-stiffness body for the new RX-7 is discussed under three subjects: 1. Contributions of vehicle components to vehicle stiffness 2. Effective procedure for developing vehicle high stiffness and lightweight construction with emphasis on calculation analysis 3. New RX-7's body structure and accomplishment