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The authors have reported significant smoke reduction in twin shaped semi-premixed diesel combustion with a newly designed combustion chamber to distribute the first and the second sprays into upper and lower layers. However, the first stage premixed combustion tends to advance far from the TDC, resulting in lowering of thermal efficiencies. In this report, improvement of thermal efficiency by optimizing the combustion phase with lower ignitability fuels was identified with the divided combustion chamber. The experiment was conducted with four fuels with different cetane numbers. The first stage premixed combustion can be retarded to the optimum phase with the fuel with cetane number 38, establishing high efficiencies.

In this paper, a newly developed Active Noise Control (ANC) system is introduced, that effectively reduces road noise, which becomes a major issue with electrified vehicles, and that enhances vehicle interior sound levels matching seamless acceleration by electric drive. Conventionally, reducing road noise using ANC requires numerous sensors and speakers, as well as a processor with high computing power. Therefore, the increase in system cost and the complexity of the system are obstacles to its spread. To overcome these issues, this system is developed based on four concepts. The first is a modular system configuration with unified interface to apply to various vehicle types and grades. The second is the integration and optimal placement of noise source reference sensors to achieve both reduction in number of parts and noise reduction performance.

Honda has developed a new hybrid system targeting the C and D segments that aims for the latest environmental performance, high fuel economy, and enhanced acceleration feeling in driving. The new engine to be applied to this new hybrid system has been developed with the goal of expanding the high thermal efficiency range, realizing the latest environmental performance, and high quietness. The new engine has adopted the Atkinson cycle and cooled exhaust gas recirculation (EGR) carried over from the previous model [1], and employed an in-cylinder direct fuel injection system with fuel injection pressure of 35 MPa. The combustion chamber and ports have been newly designed to match the fuel system changes. By realizing high-speed combustion, the engine realized a high compression ratio with the mechanical compression ratio of 13.9.

The application of optical diagnostics in turbulent reactive flows often suffers from the beam steering (BS) effects, resulting in degraded image quality and/or measurement accuracy. This work investigated a method to correct the BS effects to improve the accuracy of optical diagnostics, with particle imagine velocimetry (PIV) measurements on turbulent reactive flames as an example. The proposed method used a guiding laser to correct BS. Demonstration in laboratory turbulent flames showed promising results where the accuracy of PIV measurement was significantly enhanced. Applicability to more complicated and practical situations are discussed.

According to some papers, the label fuel economy and the actual fuel economy experienced by the customers may exhibit a gap. One of the reasons may stem from the aerodynamic drag variations due to the natural wind. The fuel consumption is measured through bench test under several driving modes by using the road load as input condition. The road load is measured through the coast down test under less wind ambient conditions as determined by each regulation. The present paper aims to analyze the natural wind conditions encountered by the vehicle on public roads and to operate a comparison between the fuel consumptions and the driving energy. In this paper, the driving energy is calculated by the aerodynamic drag from the natural wind specifications and driving conditions. This driving energy and the fuel consumptions show good correlation. The fuel consumption is obtained from the vehicle Engine control unit(ECU) data.

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.

Recent trends to downsize engines have resulted in lighter weight and greater compactness. At the same time, however, power density has increased due to the addition of turbocharger and other such means to supplement engine power and torque, and this has increased the thermal and mechanical load. In this kind of environment, corrosion of the copper alloy bushing (piston pin bushing) that is press-fitted in the small end of the connecting rod becomes an issue. The material used in automobile bearings, of which the bushing is a typical example, is known to undergo sulfidation corrosion through reaction with an extreme-pressure additive Zinc Dialkyldithiophosphate (ZnDTP) in the lubricating oil. However, that reaction path has not been clarified. The purpose of the present research, therefore, is to clarify the reaction path of ZnDTP and copper in an actual engine environment.

Today’s progress in electronic technologies is advancing the process of making vehicles more intelligent, and this is making driving safer and more comfortable. In recent years, numerous vehicles equipped with high-level Advance Driving Assist System (ADAS) have been put on the market. High-level ADAS can detect impending lane deviation, and control the vehicle so that the driver does not deviate from the lane. Lane departure prevention systems are able to detect imminent departure from the road, allowing the driver to apply control to prevent lane departure. These systems possess enormous potential to reduce the number of accidents resulting from road departure, but their effectiveness is highly reliant on their level of acceptance by drivers.

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.

A rubber sealing for a water-cooled battery pack plays a significant role to prevent water immersion into the inside of the pack. The appropriate design including the adjacent parts achieves a weight reduction of the battery pack by reducing the battery tray thickness and the quantity of bolts used in the whole battery pack. Generally, finite element analysis (FEA) is effective for the design optimization before proto-typing. However, the application to the sealing for a battery pack requires a large scale analysis, including the complicated contacts and large deformation of the rubber sealing, and results in unpractically long computation time and frequent computation errors due to the finite element distortion. A multi-scale structural analysis and the process on the rubber sealing for the battery pack has been developed to solve the above issues. This approach consists of 3 steps, which are single-unit, entire-scale and detailed structural analysis.

The dynamic performance of battery electric vehicles (BEV) is affected by battery output power, which depends on state of charge (SOC) and the temperature of battery cells. The temperature of the batteries varies in particular with the environment, in which the user stores the vehicle, and the battery output power. It is therefore necessary to employ thermal management systems that can control the battery temperature within the optimal range under severely hot and cold conditions in BEVs. A highly sophisticated thermal management system and its operation strategy were developed to fulfill the above requirements. The powertrain components to be thermo-controlled were located into two coolant circuits having different temperature range. The compact and efficient front-end heat exchangers were designed to optimally balance the cooling performance of powertrain, cabin comfort, vehicle aerodynamics and the vehicle design.

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.

It is experimentally known that the surface color of bearing balls gradually becomes brown during long term operation of the bearings under appropriate lubrication conditions. That exhibits the possibility of an estimation method for residual life of ball bearings without any abnormal wear on the surfaces by precise color measurements. Therefore, we examined what set colors on bearing balls by surface observation using scanning electron microscopy and subsurface analysis using transmission electron microscopy. Results showed that an amorphous carbon layer had gradually covered ball surfaces during operation of the bearings. The layer not only changed ball color but also made overall ball shapes closer to a complete sphere. The report also introduces a uniquely developed color analyzer which enabled color measurements on metallic surfaces, such as the above-mentioned balls.

Adhesive bonding is a key technology for the lighter weight of battery pack trays using aluminum material. A robust design method of adhesive bonding with the required strength for battery pack structure after degradation was developed to minimize variability of strength under various noise conditions. The parameter design based on Taguchi methods determined the optimum adhesive condition of the bonding process. To guarantee strength after degradation, it is essential to select a robust adhesive material and to minimize the strength variation derived from the adhesive material. The functional evaluation, which includes experimental design method, determined adhesive material with the minimum strength variation among material candidates. Then, robustness of the adhesive material itself has been evaluated as the result of collaboration with the adhesive material supplier. This analysis was able to regulate the compound ratio of raw materials without reducing the adhesive strength.

Turbine housings in car engine turbochargers, which use costly stainless steel castings, account for nearly 50% of the parts cost of a turbocharger. They are also the component which controls the competitiveness of the turbocharger, in terms of both function and cost. In this research, focusing on thermal fatigue resistance which is one of the main functions demanded of a turbine housing, achieving reduction in wall thickness while securing sufficient thermal fatigue resistance, it is possible to reduce the amount of material used in the turbine housing and aimed for cost reduction. Therefore, we built a method to quantitatively predict, using 3D FEM, the lifespan from the initiation of thermal fatigue cracking to the formation of a penetrating crack which leads to gas leakage.

In engines having an inline four cylinder DOHC configuration, the rotational vibrations of camshaft increase at high engine speeds above 10000 rpm, causing an increase of tension in the cam chain. It is therefore difficult to realize an optimum designing of a cam chain system when the durability has to be taken into considerations. Using the simulation we analyzed in this research how the rotational vibrations and tension increase at high engine speeds in an inline four cylinder DOHC engine. As its consequent, it is understood that the increases of rotational vibrations and tension caused by the resonance of the spring mass vibration system in which the cam chain serves as springs and the camshafts as the equivalent masses. Also it is found out that the vibration system is of a unique non-linear type in which the resonance of the fourth order frequency is also excited by the crankshaft torque fluctuations of the second order frequency.

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.

Honda has developed the 2018 model CLARITY PLUG-IN HYBRID. Honda’s new plug-in hybrid is a midsize sedan and shares a body platform with the CLARITY FUEL CELL and the CLARITY ELECTRIC. The vehicle’s electric powertrain boosts driving performance as an electric vehicle (EV) over Honda’s previous plug-in hybrid. The CLARITY PLUG-IN HYBRID’s electric powertrain consists of a traction motor and generator built into the transmission, a Power Control Unit (PCU) positioned above the transmission, an Intelligent Power Unit (IPU) fitted under the floor, and an onboard charger fitted below the rear trunk. The PCU integrates an inverter that drives the traction motor, an inverter that drives the generator, and a DC-DC converter to boost battery voltage (referred to as a “Voltage Control Unit (VCU)” below).

Increasing the strength of materials is effective in reducing weight and boosting structural part performance, but there are cases in where the residual strain generated during the process of manufacturing of high-strength materials results in a decline of durability. It is therefore important to understand how the residual strain in a manufactured component changes due to processing conditions. In the case of a connecting rod, because the strain load on the connecting rod rib sections is high, it is necessary to clearly understand the distribution of strain in the ribs. However, because residual strain is generally measured by using X-ray diffractometers or strain gauges, measurements are limited to the surface layer of the parts. Neutron beams, however, have a higher penetration depth than X-rays, allowing for strain measurement in the bulk material.