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Powertrain development requires an efficient development process with no rework and model-based development (MBD). In addition, to performance design that achieves low CO2 emissions is also required. Furthermore, it also demands fuel economy performance considering real-world usage conditions, and in North America, the EPA (U.S. Environmental Protection Agency) 5-cycle, which evaluates performance in a combination of various environments, is applied. This evaluation mode necessitates predicting performance while considering engine heat flow. Particularly, simulation technology that considers behavior based on engine temperature for Hybrid Electric Vehicle (HEV) is necessary. Additionally, in the development trend of vehicle aerodynamic improvement, variable devices like Active Grille Shutter (AGS) are utilized to contribute to reducing CO2 emissions.

In recent years, electrification of powertrains has been promoted to improve fuel efficiency and CO2 emissions. Along with electrification, it is possible to reduce engine usage frequency and improve the fuel efficiency in traveling. Especially in a hybrid electric vehicle (HEV), the state changes from motor assist mode to engine firing mode. As a result, stay time in eigenvalue of a powertrain is shortened, and vibration of the vehicle body at the engine start situation is able to be reduced as compared with conventional engine-driven vehicle. However, since the HEV is equipped with a high compression ratio engine for improving fuel economy, there is cause for concern that excitation force generated by the powertrain at the time of engine start increases. Also, the vehicle body vibration at engine start situations requires further consideration, because the operation frequency of engine decreases.

Low pressure cooled exhaust gas recirculation (EGR) to suppress engine knocking is increasingly being used to downsize engines and increase the compression ratio to improve thermal efficiency. This study aims to develop an ignition system to extend the EGR limit and EGR operation area. The ignition system must be improved to enhance ignitability of a mixture of fuel and air. In this paper, we focus on ignition energy of the ignition coil and summarize experimental results on a test dyno obtained by using reinforced conventional ignition coil on the basis of ignition energy and engine speed. As engine speed (mixture flow velocity between ignition plug electrode-gap) and EGR ratio were increased, the secondary energy requirement of the ignition coil was increased. This increase was considered to be caused by an increase of mixture flow velocity at the plug gap and a decrease of laminar flame velocity as EGR ratio increased.

A technique of estimating particulate matter (PM) from gasoline direct injection engines is proposed that is used to compute mass density and particle number density of PM by using fuel mass in rich mixtures obtained by using non-combustion computational fluid dynamics (CFD). The CFD code that was developed by the authors employed a Cartesian coordinates system as a discretization method and large eddy simulation (LES) as a turbulence model. Fuel spray droplets were treated with the discrete droplet model (DDM). The code was verified with some experimental data such as those obtained from in-cylinder gas-flows with a laser Doppler velocimeter (LDV) and in-cylinder fuel concentration with laser induced fluorescence (LIF). PM emissions from a single-cylinder gasoline direct injection engine were measured with an electrical low pressure impactor (ELPI) to determine the model constants that were required in the estimation model.

The robustness control for homogeneous charge compression ignition (HCCI) using a crank angle sensor and a knock sensor has been estimated. On the other hand, an ion current sensor is used as a countermeasure against abnormal combustion with downsized and higher compression ratio engines. This sensor can generally be adopted in engine systems. Therefore, we examined the application of an ion current sensor to robustness control for HCCI. The purpose of this research was to develop a method of detecting combustion conditions to make HCCI engines more robust. Therefore, we evaluated the performance of the ion current sensor. Experimental results comparing ion intensity detection in HCCI. The detection value of the ion current sensor changed based on the form of combustion. Experimental results showed that the heat release rate increased with an increase in ion signals appear during the same time at approximately in both spark ignition (SI) and HCCI.

The purpose of this study was to develop a method for detecting combustion fluctuation and noise to improve homogeneous charge compression ignition (HCCI) engine system robustness. In the present study, the maximum rate of pressure rise (dp/dθmax) was used as an index of noise and the standard deviation of indicated mean effective pressure (σIMEP) was used as an index of HCCI combustion fluctuation. A knock sensor and crank angle sensor, which are equipped with a conventional spark ignition (SI) engine system, were used as combustion noise and fluctuation detection sensors. For acquiring knock sensor signals, the time series of data were analyzed using fast Fourier transformation (FFT). The integral value of the power spectrum shows the vibration intensity of the engine. For acquiring crank angle sensor signals, the time series of data were analyzed using the average calculation of crankshaft revolution.