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A new index for evaluating load path dispersion is proposed, using a structural load path analysis method based on the concept of U* , which expresses the connection strength between a load point and an arbitrary point within the structure enables the evaluation of the load path dispersion within the structure by statistical means such as histograms and standard deviations. Presenter Tadashi Naito, Honda R&D Co., Ltd.

Honda's technology applied to CR-Z HEV propulsion system. Presenter Takeo Nishibori, Honda R&D Co., Ltd.

Currently, two consolidated aftertreatment technologies are available for the reduction of NOx emissions from diesel engines: Urea SCR (Selective Catalytic Reduction) systems and LNT (Lean NOx Trap) systems. Urea SCR technology, which has been widely used for many years at stationary sources, is becoming nowadays an attractive alternative also for light-duty diesel applications. However, SCR systems are much more effective in NOx reduction efficiency at high load operating conditions than light load condition, characterized by lower exhaust gas temperatures.

A new index U* for evaluating load path dispersion is proposed, using a structural load path analysis method based on the concept of U*, which expresses the connection strength between a load point and an arbitrary point within the structure. U* enables the evaluation of the load path dispersion within the structure by statistical means such as histograms and standard deviations. Different loading conditions are applied to a body structure, and the similarity of the U* distributions is evaluated using the direction cosine and U* 2-dimensional correlation diagrams. It is shown as a result that body structures can be macroscopically grasped by using the U* distribution rather than using the stress distribution. In addition, as an example, the U* distribution of torsion loading condition is shown to comprehensively include characteristics of the U* distribution of other loading conditions.

HCCI combustion can realize low NOx and particulate emissions and high thermal efficiency. Therefore, HCCI combustion has a possibility of many kinds of applications, such as an automotive powertrain, general-purpose engine, motorcycle engine and electric generator. However, the operational range using HCCI combustion in terms of speed and load is restricted because the onset of ignition and the heat release rate cannot be controlled directly. For the extension of the operational range using either an external supercharger or a turbocharger is promising. The objective of this research is to investigate the effect of the intake pressure on the HCCI high load limit and HCCI combustion characteristics with blowdown supercharging (BDSC) system. The intake pressure (Pin) and temperature (Tin) were varied as experimental parameters. The intake pressure was swept from 100 kPa (naturally aspirated) to 200 kPa using an external mechanical supercharger.

In the automobile industries, weight reduction has been investigated to improve fuel efficiency together with reduction of CO2 emission. In such circumstance, it becomes necessity to make an electric power steering (EPS) more compact and lightweight. In this study, we aimed to have a smaller and lighter EPS gear size by focusing on an impact load caused at steering end. In order to increase the shock absorption energy without increase of stopper bush size, we propose new theory of impact energy absorption by not only spring function but also friction, and a new stopper bush was designed on the basis of the theory. The profile of the new stopper bush is cylinder form with wedge-shaped grooves, and when the new stopper bush is compressed by the end of rack and the gear housing at steering end, it enables to expand the external diameter and produce friction. In this study, we considered the durability in the proposed profile.

This paper will discuss the stress reduction of the worm wheel for an electric power steering (EPS) system. The research discussed in this paper focused on the worm wheel, the EPS component that determines the maximum diameter of the system. If the stress of the worm wheel could be reduced without increasing in size, it would be possible to reduce the size of the worm wheel and EPS system. In order to reduce the stress of the worm wheel, the conventional design method has extended the line-of-action toward outside of the worm wheel to increase the contact ratio of the gears and these method lead to an increase in the outer diameter. In order to address this issue, past research proposes the basic concept to extend line-of-action toward the inside of the worm wheel. And this new meshing theory was named MUB (Meshing Under Base-circle) theory. In this paper, characteristics of meshing of the gear formed by MUB theory are determined in more detail.

An air-dam spoiler is commonly used to reduce aerodynamic drag in production vehicles. However, it inexplicably tends to show different performances between wind tunnel and coast-down tests. Neither the reason nor the mechanism has been clarified. We previously reported that an air-dam spoiler contributed to a change in the wake structure behind a vehicle. In this study, to clarify the mechanism, we investigated the coefficient of aerodynamic drag CD reduction effect, wake structure, and underflow under different boundary layer conditions by conducting wind tunnel tests with a rolling road system and constant speed on-road tests. We found that the air-dam spoiler changed the wake structure by deceleration of the underflow under stationary floor conditions. Accordingly, the base pressure was recovered by approximately 30% and, the CD value reduction effect was approximately 10%.

A new nitriding technology and material technology have been developed to increase the strength of microalloyed gears. The developed nitriding technology makes it possible to freely select the phase composition of the nitride compound layer by controlling the treatment atmosphere. The treatment environment is controlled to exclude sources of supply of [C], and H2 is applied as the carrier gas. This has made it possible to control the forward reaction that decomposes NH3, helping to enable the stable precipitation of γ′-phase, which offers excellent peeling resistance. A material optimized for the new nitriding technology was also developed. The new material is a low-carbon alloy steel that makes it possible to minimize the difference in hardness between the compound layer and the substrate directly below it, and is resistant to decline in internal hardness due to aging precipitation in the temperature range used in the nitriding treatment.

In this research, a new wire material made using surface-reforming heat treatment was developed in order to enhance the corrosion fatigue resistance of suspension springs. The aim of surface reforming is to improve hydrogen embrittlement characteristics through grain refinement and to improve crack propagation resistance by partial softening of hardness. The grain refinement method used an α'→γ reversed transformation by rapid short-term heating in repeated induction heating and quenching (R-IHQ) to refine the crystal grain size of SAE 9254 steel spring wire to 4 μm or less. In order to simultaneously improve the fatigue crack propagation characteristics, the possibility of reducing the hardness immediately below the spring surface layer was also examined. By applying contour hardening in the second IHQ cycle, a heat affected zone (HAZ) is obtained immediately below the surface.

When a vehicle is in motion, noise is generated in the cabin that is composed of noise in multiple narrow-frequency bands and caused by input from the road surface. This type of noise is termed low-frequency-band road noise, and its reduction is sought in order to increase occupant comfort. The research discussed in this paper used feedback control technology as the basis for the development of an active noise control technology able to simultaneously reduce noise in multiple narrow-frequency bands. Methods of connecting multiple single-frequency adaptive notch filters, a type of adaptive filter, were investigated. Based on the results, a method of connecting multiple filters that would mitigate mutual interference caused by different controller transmission characteristics was proposed.

The process for setting the marketability targets and achievement methods for automotive interior quietness (as related to air borne noise above 400Hz, considered the high frequency range) was established. With conventional methods it is difficult to disseminate the relationship between the performance of individual parts and the overall vehicle performance. Without new methods, it is difficult to propose detailed specifications for the optimal sound proof packages. In order to make it possible to resolve the individual components performance targets, the interior cavity was divided into a number of sections and the acoustic performance of each section is evaluated separately. This is accomplished by evaluating the acoustical energy level of each separate interior panel with the unit power of the exterior speaker excitation. The applicability of the method was verified by evaluating result against predicted value, using the new method, during actual vehicle operation.

Cabin quietness is one of the important factors for product marketability. In particular, the importance of reducing road noise is increasing in recent years. Methods that reduce acoustic sensitivity as well as those that reduce the force transferred from the suspension to the body (the suspension transfer force) are used as means of reducing road noise. Reduction of the compliance of the body suspension mounting points has been widely used as a method of reducing acoustic sensitivity. However, there were cases where even though this method reduced acoustic sensitivity, road noise did not decrease. This mechanism remained unclear. This study focused on the suspension transfer force and analyzed this mechanism of change using the transfer function synthesis method. The results showed that the balance between the body's suspension mounting points, suspension bush, and suspension arm-tip compliance is an important factor influencing the change in suspension transfer force.

In brake squeal analyses using FE models, minimizing the discrepancies in vibration characteristics between the measurement and the simulation is a key issue for improving its reproducibility. The discrepancies are generally adjusted by the shape parameters and/or material properties applied to the model. However, the discrepancy cannot be easily adjusted, especially, for the vibration characteristic of the disc model of a motorcycle. One of the factors that give a large impact on this discrepancy is a thermal history of the disc. That thermal history includes the one experienced in manufacturing process. In this paper, we examine the effects of residual stress on the natural frequency of motorcycle discs. The residual stress on the disc surface was measured by X-ray stress measurement method. It was followed by an eigenvalue analysis. In this analysis, we developed a unique method in which the residual stress was substituted by thermal stress.

We developed “Two-Stage Method” that makes it possible to evaluate the automotive suitability of FM receivers by generating a virtual radio wave environment on a PC. The major technological challenge for the Two-Stage Method was reproducing an actual radio wave environment on PC. It was necessary to estimate the characteristics of the FM radio wave environment in tests using the Multiple Signal Classification (MUSIC) method. However, when the MUSIC method is applied to FM reception, restrictions in factors including the number of array antenna elements and the occupied bandwidth result in issues of separation performance in relation to multipath waves in urban environments. We therefore developed a MUSIC Method using a virtual array antenna, making it possible to create combinations of numbers of array and sub-array elements as desired, thus boosting multipath wave separation performance. This development was reported at the 2015 SAE World Congress.

The suitability of FM radio receivers for automobiles has conventionally been rated by evaluating reception characteristics for broadcast waves in repeated driving tests in specific test environments. The evaluation of sound quality has relied on the auditory judgment due to difficulties to conduct quantitative evaluations by experiments. Thus the method had issues in terms of the reproducibility and objectivity of the evaluations. To address these issues, a two-stage method generating a virtual radio wave environment on a PC was developed. The research further defined the multipath distortion rate, MDr, as an index for the sound quality evaluation of FM receivers, and the findings concerning the suitability of the evaluation of FM terminals for automobiles were reported at the 2015 SAE World Congress.

In the early stages of aerodynamic development of commercial vehicles, the aerodynamic concept is balanced with the design concept using CFD. Since this development determines the aerodynamic potential of the vehicle, CFD with high accuracy is needed. To improve its accuracy, spatial resolution of CFD should be based on flow phenomenon. For this purpose, to compare aerodynamic force, pressure profile and velocity vector map derived from CFD with experimental data is important, but there are some difficulties to obtain pressure profile and velocity vector map for actual vehicles. At the point of pressure measurement for vehicles, installation of pressure taps to the surface of vehicle, i.e., fuel tank and battery, is a problem. A new measurement method developed in this study enables measurement of surface pressure of any desired points. Also, the flexibility of its shape and measuring point makes the installation a lot easier than the conventional pressure measurement method.

Vehicles are required durability in various environments all over the world. Especially water resistance on flooded roads is one of the important issues. To solve this kind of problem, a CFD technology was established in order to predict the water resistance performance of the vehicle at the early development stage. By comparison with vehicle tests on flooded roads, it is clarified the following key factors are required for accurate prediction; the vehicle velocity change, the vehicle height change and the air intake flow rate. Moreover, these three key factors should be appropriately determined from vehicle and engine specification to predict water intrusion for flooded roads at the early stage of development. In this paper, a methodology which determines appropriate analysis conditions mentioned above for flooding simulation from vehicle and engine specification is described. The methodology enables us to determine whether the vehicle provides sufficient waterproofness.

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.

Bioethanol is being used as an alternative fuel throughout the world based on considerations of reduction of CO2 emissions and sustainability. It is widely known that ethanol has an advantage of high anti-knock quality. In order to use the ethanol in ethanol-blended gasoline to control knocking, the research discussed in this paper sought to develop a fuel separation system that would separate ethanol-blended gasoline into a high-octane-number fuel (high-ethanol-concentration fuel) and a low-octane-number fuel (low-ethanol-concentration fuel) in the vehicle. The research developed a small fuel separation system, and employed a layout in which the system was fitted in the fuel tank based on considerations of reducing the effect on cabin space and maintaining safety in the event of a collision. The total volume of the components fitted in the fuel tank is 6.6 liters.