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Powertrain electrification is becoming increasingly common in the transportation sector to address the challenges of global warming and deteriorating air quality. This paper introduces a novel “Build Your Hybrid” approach to experience and test various hybrid powertrain concepts. This approach is applied to the light commercial vehicles (LCV) segment due to the attractive combination of a Diesel engine and a partly electrified powertrain. For this purpose, a demonstrator vehicle has been set up with a flexible P02 hybrid topology and a prototype Hybrid Control Unit (HCU). Based on user input, the HCU software modifies the control functions and simulation models to emulate different sub-topologies and levels of hybridization in the demonstrator vehicle. Three powertrain concepts are considered for LCVs: HV P2, 48V P2 and 48V P0 hybrid. Dedicated hybrid control strategies are developed to take full advantage of the synergies of the electrical system and reduce CO2 and NOx emissions.

When evaluating the wear properties of slide bearings for car engines, it is a common practice to conduct long-term physical test using a bearing tester for screening purposes according to the revolution speed of the shaft, supply oil temperature and bearing pressure experienced in the actual use of engines. The loading waveform applied depends on the capability of the tester that is loaded, and it is often difficult to apply a loading waveform equivalent to that of actual engines. To design an engine that is more compact or lighter, it is necessary to reduce the dimensions of slide bearings and the distance between bearings. This requires loading tests on a newly designed engine by applying a loading waveform equivalent to that of actual engines to slide bearings and their vicinity before conducting a firing test. We therefore conducted an engine firing test by attaching thin-film sensors to the slide bearing part of the engine and measured the actual load distribution.

This study attempted to faithfully reproduce and scientifically analyze the process of formation of the exhaust pipe of the winning RA272 engine used in Formula One in the 1960's, using the waza (skills) employed in its fashioning, which have been handed down by its makers. This analysis showed that the manual bending method, used to create the RA272 exhaust pipe, which was filled with sand and bent while being flame-heated, without the use of figures or molds, was superior to the mechanical bending method of that time, from the standpoint of short-term period of production. We have determined that the pipe displays that the microstructure of the material remains stable, even at exhaust temperatures of 700°C to 900°C, and that useful information on the pipe's shape stability and mechanical strength has been provided.

New 12 V/48 V power net architectures are potential solutions to close the gap between customer needs and legislative requirements. In order to exploit their potential, an increased effort is needed for functional implementation and hardware integration. Shifting of development tasks to earlier phases (frontloading) is a promising solution to streamline the development process and to increase the maturity level at early stages. This study shows the potential of the frontloading of development tasks by implementing a virtual 48 V mild hybridization in an engine-in-the-loop (EiL) setup. Advanced simulation technics like functional mock-up interface- (FMI) based co-simulation are utilized for the seamless integration of the real-time (RT) simulation models and allow a modular simulation framework as well as a decrease in development time.

When a vehicle is cruising, unpleasant noise in the 4 to 5 KHz high-frequency band can be heard at the center of all seats in the vehicle cabin. In order to specify the source of this noise, the correlation between the noise and airborne noise from the outer surface of the transmission was determined, and transfer path analysis was conducted for the interior of the transmission. The results indicated that the source of the noise was the 0th-order breathing mode specific to the drive motor. To make it possible to predict this at the desk, a vibrational analysis method was proposed for drive motors made up of laminated electrical steel sheets and segment-type coils. Material properties data for the electrical steel sheets and coils was employed in the drive motor vibrational analysis model without change. The shapes of the laminated electrical steel sheets and coils were also accurately modeled.

A new motor has been developed that combines the goals of greater compactness, increased power and a quiet drive. This motor is an interior permanent magnet synchronous motor (IPM motor) that combines an interior permanent magnet rotor and a stator with concentrated windings. In addition, development of the motor focused on the slot combination, the shape of the magnetic circuits and the control method all designed to reduce motor noise and vibration. An 8-pole rotor, 12-slot stator combination was employed, and a gradually enlarged air gap configuration was used in the magnetic circuits. The gradually enlarged air gap brings the centers of the rotor and the stator out of alignment, changing the curvature, and continually changing the amount of air gap as the rotor rotates. The use of the gradually enlarged air gap brings torque degradation to a minimum, and significantly reduces torque fluctuation and iron loss of rotor and stator.

Downsizing or higher compression ratio of SI engines is an appropriate way to achieve considerable improvements of part load fuel efficiency. As the compression ratio directly impacts the engine cycle thermal efficiency, it is important to increase the compression ratio in order to reduce the specific fuel consumption. However, when operating a highly boosted / downsized SI engine at full load, the actual combustion process deviates strongly from the ideal Otto cycle due to the increased effective loads requiring ignition timing delay to suppress abnormal combustion phenomena such as engine knocking. This means that for an optimal design of an SI engine between balances must be found between part load and full load operation. If the knocking characteristic can be accurately predicted beforehand when designing the combustion chamber, a reduction of design time and /or an increase in development efficiency would be possible.

Lean burn gasoline spark-ignition engines can support the reduction of CO2 emissions for future hybrid passenger cars. Very high efficiencies and very low NOx raw emissions can be achieved, if relative air/fuel ratios λ of 2 and above can be reached. The biggest challenge here is to assure a reliable ignition process and to enhance the fuel oxidation in order to achieve a short burn duration and a good combustion stability. This article aims at introducing an innovative combustion system fully optimized for ultra-lean operation and very high efficiency. Thereto, a new cylinder head concept has been realized with high peak firing pressure capability and with a low surface-to-volume ratio at high compression ratios. 1D and 3D simulations have been performed to optimize the compression ratio, charge motion and intake valve lift. Numerical calculations also supported the development of the ignition system.

There are strong demands for reduced production costs of ordinary bolts, of which a large number are used throughout automobiles. In addition, there are continued demands for higher performance and lower weight in automobiles. For this reason, there is an increasing trend to develop steel for high strength bolts or to adopt the plastic region tightening method. At present, the principal materials used in high strength bolts of class 10.9 are medium carbon alloy steel. When a low carbon boron steel bolt is used as a class 10.9 bolt under high stress, delayed fracture may occur, so that these cannot always be used for the body and chassis applications. The authors have developed a new low carbon boron steel with increased delayed fracture strength on the same order as that of JIS-SCM435 (equivalent to SAE4135) medium carbon alloy steel. Attention was focused principally on decreasing the amounts of phosphorus and sulfur in the steel.

A second-generation power control unit (PCU) for a two-motor hybrid system is proposed. An optimally designed power module, which is a key component of the PCU, is applied to increase heat-resistant temperature, while the basic structure of the first generation is retained and the power semiconductor chip is directly cooled from the single side. In addition to the optimum design, by decreasing the power loss as well as increasing the heat-resistant temperature of the power semiconductors (IGBT: Insulated Gate Bipolar Transistor and FWD: Free Wheeling Diode), the proposed PCU has attained 25% higher power density and 23% smaller size compared to first-generation units, maintaining PCU efficiency (fuel economy). To achieve a high yield rate in the power module assembly process, a new screening technology is adopted at the initial stage of power module manufacturing.

New combustion processes require an understanding of the highly three-dimensional flow field to effectively decrease fuel consumption and pollutant emission. Due to the complex spatial character of the flow the knowledge of the development of the flow in an extended volume is necessary. Previous investigations were able to visualize the discrete three-dimensional flow field through multi-plane stereoscopic PIV. In this study, cycle resolved tomographic particle-image velocimetry measurement have been performed to obtain a fully resolved representation of the three-dimensional flow structures at each instant. The analysis is based on the measurements at 80°, 160°, and 240° after top dead center(atdc) such that the velocity distributions at the intake, the end of the intake, and the compression stroke at an engine speed of 1,500 rpm are discussed in detail.

Honda announced an independent right and left rear toe control system (first generation) in 2013 and presented it as the world's first. As stated in a previous paper, “Independent Left and Right Rear Toe Control System,” with this system Honda has achieved a balance between an enjoyable driving experience in which handling is performed at the driver's will (“INOMAMA” handling) and stable driving performance.(1) This first generation is optimally designed to the vehicle specifications such as suspension axial force and steering gear ratio of the vehicle to which the system is applied. For more widespread application of independent rear toe control technology, a next generation system (second generation) has been developed, which achieves both cost reduction and flexible system performance which can be adapted to a variety of vehicles. The system development began by setting the required target performance with consideration for adaptation to various car models.

The weight-saving requirements for automobiles are important. In order to produce a lighter engine, an aluminum block with cast-iron liners and a hypereutectic aluminum-silicon alloy block have been developed. (1)*, (2), (3), (4), (5), (6) We developed a new aluminum engine block which has the cylinder bore surface structure reinforced with short ceramic fiber. We also established technology suitable for mass-production including a fiber preform process and a non-destructive inspection method. In this paper, the optimum properties and production technology of MMC engine blocks are introduced. A portion of the paper is dedicated to the results of a comparison study between a new light-weight aluminum engine block, a hypereutectic aluminum-silicon engine block and an aluminum engine block with cast-iron liners.

A method of predictive simulation of flow-induced noise using computational fluid dynamics has been developed. The goal for the developed method was application in the vehicle development process, and the target of the research was therefore set as balancing the realization of a practical level of predictive accuracy and a practical computation time. In order to simulate flow-induced noise, it is necessary to compute detailed eddy flows and changes in the density of the air. In the research discussed in this paper, the occurrence or non-occurrence of flow-induced noise was predicted by conducting unsteady compressible flow calculation using large eddy simulation, a type of turbulence model. The target flow-induced noise for prediction was narrow-band noise, a type of noise in which sound increases in specific frequency ranges.

Modern automotive development evolves beyond artificial intelligence for highly automated driving, and toward an interconnected manifold of data-driven development processes. Widely used analytical system modelling struggles with rising system complexity, invoking approaches through data-driven system models. We consider these as key enablers for further improvements in accuracy and development efficiency. However, literature and industry have yet to thoroughly discuss the relevance and methods along the vehicle development cycle. We emphasize the importance of data-driven system models in their distinct types and applications along the developing process, from pre-development to fleet operation. Data-driven models have proven in other works to be fast approximators, of high accuracy and adaptive, in contrast to physics-based analytical approaches across domains.

The moment of inertia of the crankshaft cannot be ignored when analyzing the dynamics of a motorcycle. In this research, the tire friction force (calculated by drag and tire side force) was used as an index of the drive performance. The ratio of roll rate and steering torque (here after referred to as a roll rate gain) was used as an index of the cornering performance, and it was analyzed as the influence of the moment of inertia of a crankshaft on the drive performance as well as cornering performance. As a result, the influence on drive performance and cornering performance by the moment of inertia has been found.

The reduction of fuel consumption is of great importance to automobile manufacturers. As a prospective means to achieve fuel economy, lean burn is being investigated at various research organizations and automobile manufacturers and a number of studies on lean-burn technology have been reported to this date. This paper describes the development of a four-valve lean-burn engine; especially the improvement of the combustion, the development of an engine management system, and the achievement of vehicle test results. Major themes discussed in this paper are (1) the improvement of brake-specific fuel consumption under partial load conditions and the achievement of high output power by adopting an optimized swirl ratio and a variable-swirl system with a specially designed variable valve timing and lift mechanism, (2) the development of an air-fuel ratio control system, (3) the improvement of fuel economy as a vehicle and (4) an approach to satisfy the NOx emission standard.

The “Statistical Design Support System” produces a new practical optimal design method. It can be used even on nonlinear behavior. The optimization can be carried out with this system using a small number of calculation results. The authors applied it to the design optimization of the occupant restraint system in order to reduce the injury criteria based on the crash simulation. In line with growing interest and improvements in technology on vehicle safety, it will be necessary to consider some different crash situations simultaneously. The authors made an optimal design taking into account the different collision conditions. This paper describes the effectivity analysis and the optimization.

Honda R&D has developed a throttle-by-wire (TBW) system that meets the needs of motorcycles where the attitude of the vehicle body is controlled by operation of the throttle. To gain high response and following for the throttle valve, we employed a new adaptive control algorithm. The newly developed system has an idling combustion stabilization function and a three-dimensional control function for the throttle-opening map based on running gear and engine speed. With those functions, we improved the controllability of the motorcycle, especially for small throttle openings. Furthermore, we improved the feeling of the limiter control used in maximum-speed limitation. For the overall system, intake system related devices are consolidated to improve the layout flexibility and expand the mounting options on the motorcycle.

In our preceding report [1], we showed that the thermal conductivity of a heat pipe dramatically improves during high-speed reciprocation. However, this cooling method has rarely been applied to car engine pistons because the thermal conductivity of commercially available heat pipes does not increase easily even if the pipe is subjected to high-speed reciprocation. In consideration of the data from our preceding report, we decided to investigate heat pipe designs for car engine pistons, propose an optimum design, and conduct thermal analysis of the design. As a result, we found that it is possible to transport heat from the central piston head area, where cooling is most needed, to the piston skirt area, suggesting the possibility of efficient cooling.