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5 belt wind tunnels are the most common facility to conduct the experimental aerodynamics development for production cars. Among aerodynamic properties, usually drag is the most important development target, but lift force and its front/rear balance is also important for vehicle dynamics. Related to the lift measurement, it is known that the “pad correction”, the correction in the lift measurement values for the undesirable aerodynamic force acting on wheel belt surface around the tire contact patch, must be accounted. Due to the pad correction measurement difficulties, it is common to simply subtract a fixed amount of lift values from measured lift force. However, this method is obviously not perfect as the pad corrections are different for differing vehicle body shapes, aerodynamic configurations, tire sizes and shapes.

A fuel reforming technology using a low temperature oxidation was developed to improve a NOx reduction performance of HC-SCR (Hydrocarbons Selective Catalytic Reduction) system, which does not require urea. The low-temperature oxidization of a diesel fuel in gas phase produces NOx reduction agents with high NOx reduction ability such as aldehydes and ketones. A pre-evaporation-premixing-type reformer was adopted in order to generate a uniform temperature field and a uniform fuel/air premixed gas, and to promote the low temperature oxidation efficiently. As a fundamental study, elementary reaction analysis for n-hexadecane/air premixtures was carried out to investigate the suitable reformer temperature and fuel/air equivalence ratio for generation of oxygenated hydrocarbons. It was found that the reforming efficiency was highest at the reforming temperature around 623 to 673K, and aldehydes and ketones were produced.

Understanding and prediction of flash-boiling spray behavior in gasoline direct-injection (GDI) engines remains a challenge. In this study, computational fluid dynamics (CFD) simulations using the homogeneous relaxation model (HRM) for not only internal nozzle flow but also external spray were evaluated using CONVERGE software and compared to experimental data. High-speed extinction imaging experiments were carried out in a real-size axial-hole transparent nozzle installed at the tip of machined GDI injector fueled with n-pentane under various ambient pressure conditions (Pa/Ps = 0.07 - 1.39). The width of the spray during injection was assessed by means of projected liquid volume, but the structure and timing for boil-off of liquid within the sac of the injector were also assessed after the end of injection, including cases with different designed sac volumes.

An accurate prediction of internal nozzle flow in fuel injector offers the potential to improve predictions of spray computational fluid dynamics (CFD) in an engine, providing a coupled internal-external calculation or by defining better rate of injection (ROI) profile and spray angle information for Lagrangian parcel computations. Previous research has addressed experiments and computations in transparent nozzles, but less is known about realistic multi-hole diesel injectors compared to single axial-hole fuel injectors. In this study, the transient injector opening and closing is characterized using a transparent multi-hole diesel injector, and compared to that of a single axial hole nozzle (ECN Spray D shape). A real-size five-hole acrylic transparent nozzle was mounted in a high-pressure, constant-flow chamber. Internal nozzle phenomena such as cavitation and gas exchange were visualized by high-speed long-distance microscopy.

The reduction of cycle-to-cycle variations (CCV) is a prerequisite for the development and control of spark-ignition engines with increased efficiency and reduced engine-out emissions. To this end, Large-Eddy Simulations (LES) can improve the understanding of stochastic in-cylinder phenomena during the engine design process, if the employed modeling approach is sufficiently accurate. In this work, an inhouse code has been used to investigate CCV in a direct-injected spark ignition (DISI) engine under fuel-lean conditions with respect to a stoichiometric baseline operating point. It is shown that the crank angle when a characteristic fuel mass fraction is burned, e.g. MFB50, correlates with the equivalence ratio computed as a local average in the vicinity of the spark plug. The lean operating point exhibits significant CCV, which are shown to be correlated also with the in-cylinder subfilter-scale (SFS) kinetic energy.

Metal additive manufacturing has high potential to produce automobile parts, due to its shape flexibility and unique material properties. On the other hand, residual stress which is generated by rapid solidification causes deformation, cracks and failure under building process. To avoid these problems, understanding of internal residual stress distribution is necessary. However, from the view point of measureable area, conventional residual stress measurement methods such as strain gages and X-ray diffractometers, is limited to only the surface layer of the parts. Therefore, neutron which has a high penetration capability was chosen as a probe to measure internal residual stress in this research. By using time of flight neutron diffraction facility VULCAN at Oak Ridge National Laboratory, residual stress for mono-cylinder head, which were made of aluminum alloy, was measured non-distractively. From the result of precise measurement, interior stress distribution was visualized.

In this research, a material model was developed that has orthotropic properties with respect to in-plane damage to support finite element strength analysis of components manufactured from a randomly oriented long-fiber thermoplastic composite. This is a composite material with randomly oriented bundles of carbon fibers that are approximately one inch in length. A macroscopic characteristic of the material is isotropic in in-plane terms, but there are differences in the tension and compression damage properties. In consideration of these characteristics, a material model was developed in which the damage evolution rate is correlated with thermodynamic force and stress triaxiality. In-plane damage was assumed to be isotropic with respect to the elements. In order to validate this material model, the results from simulation and three-point bending tests of closed-hat-section beams were compared and found to present a close correlation.

The cooling performance and the heat resistance performance of commercial vehicle are balanced with aerodynamic performance, output power of powertrain, styling, cost and many other parameters. Therefore, it is desired to predict the cooling performance and the heat resistance performance with high accuracy at the early stage of development. Among the three basic forms of heat transfer (conduction, convection and radiation), solving thermal conduction accurately is difficult, because modeling of “correct shape” and setting of coefficient of thermal conductivity for each material need many of time and efforts at the early stage of development. Correct shape means that each part should be attached correctly to generate the solid mesh with high quality. Therefore, it is more efficient and realistic method to predict the air temperature distribution around the rubber/resin part instead of using the surface temperature at the preliminary design stage.

Controllability is defined in ISO 26262 as a driver’s ability to avoid a specified harm caused by a malfunction of electrical and electronic systems installed in road vehicles. According to Annex C of Part 12 of ISO 26262, simulation is one of the techniques that the Controllability Classification Panel (CCP) can use to evaluate comprehensively the controllability class (C class) of motorcycles. With outputs of (i) an index for the success of harm avoidance and (ii) the magnitude of the rider’s compensatory control action required to avoid harm, the simulation is useful for evaluating the C class of the degrees of malfunction that cannot be implemented in practice for the sake of the test rider’s safety. To aim at supplying data that the CCP can use to judge the C class, we try to estimate the vehicle behavior and a rider’s compensatory control actions following a malfunction using vehicle dynamics simulations.

This study employed a diesel particulate generator (DPG), with an installed engine oil injector for soot and ash accumulation in a diesel particulate filter (DPF). Ash was generated by engine oil injection into the diesel burner flame. The amount of soot accumulation per loading varied from 0.5 g/L to 8 g/L while ash accumulation amount per loading was maintained at 0.5 g/L. Initially, ash accumulation distribution in the DPF was visualized using X-ray computed tomography (CT). It was revealed that the form of ash accumulation changed depending on the amount of soot accumulation before active regeneration, i.e., a large amount of soot accumulation resulted in plug ash, whereas a small amount of soot accumulation resulted in wall ash. To clarify ash accumulation mechanisms, soot and ash transport behavior in DPF during active regeneration process was directly observed using a high-speed camera through an optically accessible D-shaped cut DPF covered with a quartz glass plate.

This work investigated the mechanism of oil dilution by post injection to remove accumulated particulate matter on the diesel particulate filter of diesel engines. We developed a model to simulate post injection spray under low ambient gas pressure conditions. The model can predict the quantity of fuel mass adhered on the cylinder wall. The adhered fuel enters oil sump through the piston ring and cause oil dilution. The fuel in diluted oil evaporates during normal engine operations. We focus on the mechanism of fuel evaporation from diluted oil. The effects of engine speed and oil temperature on the evaporation were investigated. The results showed that the fuel evaporation rate increases with increasing engine speed and oil temperature. Furthermore, we developed an empirical model to predict the fuel evaporation rate of diluted oil through regression analysis with measured data.

A compact intelligent power unit capable of being installed under the rear seating was developed for the 2018 model year Accord Hybrid that is to be equipped with the SPORT HYBRID Intelligent Multi Mode Drive (i-MMD) system. The space under the rear seat features multiple constraints on dimensions. In the longitudinal direction, it is necessary to attempt to help ensure occupant leg room and to position the fuel tank; in the vertical direction, it is necessary to attempt to help ensure occupants comfort and a minimum ground clearance; and in the lateral direction, it is necessary to avoid the position of the body side frames and the penetrating section of the exhaust pipe. The technologies described below were applied in order to reduce the size of components, making it possible to position the IPU amid these constraint conditions.

In recent years along with stringent the regulations, vehicles equipped with gasoline particulate filter (GPF) have started to launch. Compared to bare GPF, coated GPF (cGPF) requires not only PN filtration efficiency, low pressure drop, but also purification performance. In the wall flow type cGPF having a complicated the pore shape, the pore structure further irregularly changes depending on the coated state of the catalyst, so it is difficult to understand the matter of in-wall. In order to advance of cGPF function, it was researched that revealing the relevance between pore structure change in the wall and GPF function. Therefore, to understand the catalyst coated state difference, cGPF of several coating methods were prepared, and their properties were evaluated by various analyses, and performance was tested.

To evaluate the relationship between the exhaust gas purification performance and the catalyst pore properties related to gas diffusion, an elementary reaction model was combined with gas diffusion into catalyst pores, referred to as the pseudo-2D gas diffusion/reaction model. It was constructed for Pt/Al2O3 + CeO2 catalyst as lean NOx catalyst. The gas diffusion was described as macro pore diffusion between the catalyst particles and meso pore diffusion within the particle. The kinetic model was composed of 26 reactions of NO/CO/O2 chemistry including 17 Pt/Al2O3 catalyst reactions and 9 CeO2 reactions. Arrhenius parameters were optimized using activity measurement results from various catalysts with various pore properties, meso pore volume and diameter, macro pore volume and diameter, particle size, and washcoat thickness. Good agreement was achieved between the measured and calculated values.

At present, measurements of running resistance are conducted outdoors as a matter of course. Because of this, the ambient temperature at the time of the measurements has a considerable impact on the measurement data. The research discussed in this paper focused on the temperature characteristic of the tires and developed a new correction technique using a special rolling test apparatus. Specifically, using a tire rolling test apparatus that made it possible to vary the ambient temperature, measurements were conducted while varying the levels of factors other than temperature that affect rolling resistance (load, inflation pressure, and speed). Next, a regression analysis was applied to the data for each factor, and coefficients for a relational expression were derived, making it possible to derive a quadratic equation for the tire rolling resistance correction formula.

When a vehicle is driven in snowy conditions, if a proper air intake design is not adopted, the snow lifted by the leading vehicles may penetrate into the engine air intake, in case of large snow ingress amount, causing a power drop. The evaluation of such risk for the intake is carried out through climatic wind tunnel tests, which cannot be conducted at the early stage of vehicle development when the prototype vehicle does not exist. In order to study that risk prior to the prototype vehicle delivery, computational fluid dynamics (CFD) which predicts the snow ingress amount accurately was established with taking into account unsteady air flow and snow accumulation. Large Eddy Simulation (LES) was used to reproduce the unsteady flow field, leading to a good agreement of the flow downstream from the snow generator with the experimental one measured by Particle Image Velocimetry (PIV). As for the snow particle behavior model, the Lagrangian method was chosen.

The ISO 26262 standard specifies the requirement for functional safety of electrical and electronic systems within road vehicles. We have accumulated case studies based on actual riding tests by subjective judgment of expert riders to define a method for determining the controllability class (C class). However, the wide variety of practical traffic environments and vehicle behaviors in case of malfunction make it difficult to evaluate all C classes in actual running tests. Furthermore, under some conditions, actual riding tests may cause unacceptable risks to test riders. In Part 12 Annex C of ISO/DIS 26262, simulation is cited as an example of a technique for comprehensive evaluations by the Controllability Classification Panel. This study investigated the usefulness of mathematical simulations for evaluating the C class of a motorcycle reproducing a malfunction in either the front or rear brakes.

We studied a simple and cost effective controlled auto ignition (CAI) combustion engine in order to achieve simultaneous reduction of NOx and soot, which are issues in diffusion combustion. The engine type was a uniflow scavenging 2-stroke engine, and the fuel used was diesel, as is common in diesel engines. We examined the position of the injector that effectively forms the premixture and realized stable operation with diesel fuel by the low pressure fuel injection device for port fuel injection (PFI), and it was found that the CAI combustion ignition timing can be controlled through setting the air/fuel ratio that obtains the optimal ignition timing per operation conditions.

In motorcycles, the mass difference between a vehicle and a rider is small and motions of a rider impose a great influence on the vehicle behaviors as a consequence. Therefore, dynamic properties of motorcycles should be evaluated not merely dealing with a vehicle but considering with a man-machine system. In the studies of a simulation for vehicle dynamics, various types of rider models have been proposed and it has already been reported that rider motions have a significant influence on the dynamic properties. However, the mechanism of the interaction between a rider and a vehicle has not been clarified yet. In our study, we focused on weave motion and constructed a full vehicle simulation model that can reflect the influences of the movements of the rider’s upper body and lower body. To construct the rider model, we first measured the vibrational characteristics of a human body using a vibration test bench.

To meet the strict emission regulations for diesel engines, an advanced processing device such as a Urea-SCR (selective catalytic reduction) system is used to reduce NOx emissions. The Real Driving Emissions (RDE) test, which is implemented in the European Union, will expand the range of conditions under which the engine has to operate [1], which will lead to the construction of a Urea-SCR system capable of reducing NOx emissions at lower and higher temperature conditions, and at higher space velocity conditions than existing systems. Simulations are useful in improving the performance of the urea-SCR system. However, it is necessary to construct a reliable NOx reduction model to use for system design, which covers the expanded engine operation conditions. In the urea-SCR system, the mechanism of ammonia (NH3) formation from injected aqueous urea solution is not clear. Thus, it is important to clarify this mechanism to improve the NOx reduction model.