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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.

When the belt contacts a pulley in a pushing belt-type CVT, vibration is generated by frictional force due to rubbing between the individual elements that are components of the belt, which is said to increase wear and noise. The authors speculated that the source of that vibration is misalignment of the secondary pulley and primary pulley V-surfaces. To verify that phenomenon, a newly developed micro data logger was attached to an element of a mass-produced metal pushing V-belt CVT and the acceleration was measured at rotations equal to those at drive (1000 to 2500 r/m). In addition, the results of calculations using a behavior analysis model showed that changes in pulley misalignment influence element vibration, and that the magnitude of the vibration is correlated to the change in the metal pushing V-belt alignment immediately before the element contacts the pulley.

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.

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.

Initiation and propagation of ductile fractures in crashed automotive components made from high strength steels are investigated in order to understand the mechanism of fracture propagation. Fracture of these components is often prone to occur at the sheet edge in a strain concentration zone under crash deformation. The fracture then extends intricately to the inside of the structure under the influence of the local stress and strain field. In this study, a simple tensile test and a 3-point bending test of high strength steels with tensile strengths of 590 MPa and 1180 MPa are carried out. In the tensile test, a coupon having a hole and a notch is deformed in a uniaxial condition. The effect of the notch type on the strain concentration and fracture behavior are investigated by using a digital imaging strain measurement system.

Honda’s purpose is to realize the joy and freedom of mobility and a sustainable society in which people can enjoy life. As such, three series of environmental vehicles-FCVs, BEVs, and PHEVs-have been developed so that users in communities around the world can select the ones best suited to their local energy circumstances and individual lifestyles. This paper discusses a structure that enhances both the motive power performance and quietness of a newly developed FCV/BEV traction motor. To enhance motive power performance, the research focused on the stator lamination technique. As for methods of affixing the stator’s layers, the practice with previous models has been adhesion lamination, using electric steel sheets that come pre-made with adhesive layers. Having adhesive layers, however, lowers the ratio (space factor) of steel sheet layers. The new motor uses electric steel sheets without an adhesive layer in order to enhance motive power performance.

The atomization of molten aluminum when injected during high-pressure die casting is analyzed to determine its effect in enhancing the strength of the product being cast. In the previously reported first step of this study, molten aluminum was injected into open space and its atomization was observed photographically. Now in the second step of the study, a simulation is conducted to determine how the molten aluminum becomes atomized at the injection nozzle (gate) and how this atomized material flows and fills the cavity. A new simulation method is developed based on large-eddy simulation coupled with the volume-of-fluid method. The simulation system is verified by comparing its output with photographs taken in the first step of the study. Simulations are then conducted using an approximation of a real cavity to visualize how it is filled by the atomized molten aluminum.

In recent years, studies have been conducted on the relationship between the J factor, which indicates flow of molten aluminum at the time of injection, and the quality of HPDC products. The flow of molten metal at a high J factor is referred to as “Atomized Flow.” The authors and others conducted studies on the relationship between the J factor and the strength of HPDC products. An area exceeding 300MPa was found in the product produced at a high J factor corresponding to the “Atomized Flow.” The defect was less in the above-mentioned position because the gas porosity was finely dispersed. Considering that the fine dispersion of gas porosity is related to the “Atomized Flow”, pictures were taken to analyze “Atomized Flow.” The molten aluminum was ejected into an open space at a high speed and the splashed conditions were photographed. From the images taken by the pulse laser permeation, the conditions of microscopic atomized flow were observed precisely.

Regulation of automotive CO2 emissions is becoming increasingly stringent throughout the world in response to global warming. For automakers, this means a focus not only on increasing the fuel economy of powertrains, but also on reducing automotive driving resistance. High expectations are held for thermoplastic fiber-reinforced plastics (FRP) for the realization of automotive weight savings while also offering high levels of productivity and recyclability. Thermoplastic FRP crush boxes display a higher level of energy absorption performance than metal (steel, aluminum, etc.) crush boxes. This will contribute to automotive weight savings and improved package design. In the case of automotive front bumper beam systems, it is necessary to realize stable load characteristics irrespective of the use environment. It is therefore necessary to consider the effects of temperature and thermoplastic resin degradation.

Amidst of the recent concerns on depletion of natural resources, a new heat resistant titanium alloy has been developed using the minimum amount of rare metals. Using Ti-811 as a basis and modifying the alloy composition to Ti-7Al-2Mo-0.2Si-0.15C-0.2Nb, the mechanical property, the creep resistance and the oxidation resistance at high temperatures are improved. At the same time, with the β transformation point shifted to a higher temperature, the hot formability is also improved. The newly developed alloy has made it possible to expand the application of titanium material to exhaust valves in reciprocating engines.

We developed a copper catalyst using zero Platinum group metals (hereafter PGMs) to fit motorcycle specific emission gas environment. Though many research reports to develop catalyst without using PGMs that are precious and costly resources are available, no reports had proven Base Metal Catalyst development to meet actual emission regulation equivalent to PGM catalysts. Compared to conventional PGM catalysts, higher temperature is required to keep high catalytic conversion efficiency by utilizing properties of this Base Metal Catalyst. Thus, this Base Metal Catalyst is located in cross coupling position, though it is rare case in motorcycle. This catalyst location could cause negative impacts on engine knocking, engine performance and drivability. This time, to overcome such negative impacts we optimized whole exhaust system, including parts around catalyst.

High-tensile steel plates and lightweight aluminum are being employed as materials in order to achieve weight savings in automotive subframe. Closed-section structures are also in general use today in order to efficiently increase parts stiffness in comparison to open sections. Aluminum hollow-cast subframe have also been brought into practical use. Hollow-cast subframe are manufactured using sand cores in gravity die casting (GDC) or low-pressure die casting (LPDC) processes. Using these manufacturing methods, it is difficult to reduce product thickness, and the limitations of the methods therefore make the achievement of weight reductions a challenge. The research discussed in this paper developed a lightweight, hollow subframe technology employing high-pressure die casting (HPDC), a method well-suited to reducing wall thickness, as the manufacturing method. Hollow-casting using HPDC was developed as a method of forming water jackets for water-cooled automotive engines.

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.

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.

Lithium-rich layered oxide, expressed as xLi2MnO3-(1-x) LiMO2 (M = Ni, Co, Mn, etc.), exhibits a high discharge capacity of 200 mAh/g or more and a high discharge voltage at a charge of 4.5 V or more. Some existing reports on cathode materials state that lithium-rich layered oxide is currently the most promising candidate as an active material for high-energy-density lithium-ion cells, but there are few reports on the degradation mechanism. Therefore, this study created a prototype cell using a lithium-rich layered cathode and a graphite anode, and analyzed the degradation mechanism due to charge and discharge. In order to investigate the causes of degradation, changes in the bulk structure and surface structure of the active material were analyzed using high-resolution X-ray diffraction (HRXRD), a transmission electron microscope (TEM), X-ray absorption fine structure (XAFS), and scanning electron microscope/energy dispersive X-ray spectroscopy (SEM-EDX).

When the strain is temporarily stopped during tensile testing of a metal, a stress relaxation phenomenon is known to occur whereby the stress diminishes with the passage of time. This phenomenon has been explained as the change of elastic strain into plastic strain. A technique was devised for deliberately causing strain dispersion to occur by applying the stress relaxation phenomenon during stamping. A new step motion that pause the die during forming was devised; it succeeded in modifying the deep-draw forming limit by a maximum of 40%. This new technique was verified through tensile and actual stamping tests. It was confirmed that the use of step motion causes the strain to disperse, thereby modifying the deep draw forming limit. The degree to which the forming limit is modified is dependent on the stop time and the temperature. Step motion technology increases the stampability of high-strength, forming-resistant materials and allows for expanded application of these materials.

Regulations that limit emissions of pollutants from gasoline-powered cars and trucks continue to tighten. More than 75% of emissions through an FTP-75 regulatory test are released in the first few seconds after cold-start. A factor that controls the time to catalytic light-off is the heat capacity of the catalytic converter substrate. Historically, substrates with thinner walls and lower heat capacity have been developed to improve cold-start performance. Another approach is to increase porosity of the substrate. A new material and process technology has been developed to significantly raise the porosity of thin wall substrates (2-3 mil) from 27-35% to 55% while maintaining strength. The heat capacity of the material is 30-38% lower than existing substrates. The reduction in substrate heat capacity enables faster thermal response and lower tailpipe emissions. The reliance on costly precious metals in the washcoat is demonstrated to be lessened.

When using aluminum for vehicle body parts to reduce weight, the high pressure die casting (HPDC) is widely applied due to its adaptability to thin-wall products, near-net-shape castability, and short casting cycle time. Since a hollow construction is advantageous to increase stiffness of body parts, there has been a need of development of techniques for casting of hollow parts by HPDC. So far, hollow casting by HPDC has been realized for small parts using sand cores. When applying that method to large parts, however, it is necessary to increase filling speed. When the filling speed is increased, the core tends to break. In this project, we have developed a method to estimate changes of pressure distribution when filling molten metal by the casting simulation in order to analyze damages to the core. Through the analysis, we discovered occurrence of impulsive pressure waves.

When fluctuations in the speed of rotation of the drive pulley are transmitted to the driven pulley via the metal V-belt, the transmitted fluctuations become attenuated as friction force approaches a state of saturation. The research discussed in this paper focused on these fluctuations in the speed of rotation and developed an index for the slip state between the belt and the pulleys. The drive and driven pulleys were regarded as a one-dimensional vibrating system connected by elastic bodies, and changes in the state matrix of the system were focused on. It was determined that when all of the eigenvalues in this state matrix become real numbers, slip speed between the belt and the pulleys increases sharply. A method was proposed of estimating this behavior of the eigenvalues from changes in the speed of rotation of the drive and driven pulleys, and indexing the current slip state.