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While there has been an empirical rule telling suspension designers that a slight rearward inclination of the wheel travel locus could improve ride harshness performance, there has not been any quantitative proof on it, to the extent of authors' knowledge. The authors planned to analyze the phenomenon by quantitatively measuring the force transmission via suspension, to find out that the amplitude of longitudinal force transmission to the sprung mass changes significantly depending on the above inclination angle. Further investigation has lead to a conclusion that the force transmission from ground to tire has a sharp directivity. And that the relationship between this direction and the direction of wheel travel is a dominant factor, which decides the magnitude of longitudinal force transmission to the sprung mass. In order to make use of the finding, the optimal wheel center locus inclination in side view has been studied, to minimize the longitudinal force transmission.

The new automatic transmission, A-HMT (Advanced Hydro-Mechanical Transmission) has been developed for the Honda ATV (All Terrain Vehicle), which is for wide applications such as utility, recreation, etc. The A-HMT system features high performance, durability and reliability attained by improving the structures from the original hydro-mechanical automatic transmission used for the scooter called “Juno”, which Honda had produced many years ago, working on the same principle. In addition to it, by applying the electronic control system, the highly responsive driveability that suits the requirements of ATV's has been realized. The A-HMT is installed in the new 500 cm3 ATV, FOURTRAX FOREMAN RUBICON, which has been introduced in the USA market since June 2000.

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.

In recent years, the slip lock-up mechanism has been adopted widely, because of its fuel efficiency and its ability to improve NVH. This necessitates that the automatic transmission fluid (ATF) used in automatic transmissions with slip lock-up clutches requires anti-shudder performance characteristics. The test methods used to evaluate the anti-shudder performance of an ATF can be classified roughly into two types. One is specified to measure whether a μ-V slope of the ATF is positive or negative, the other is the evaluation of the shudder occurrence in the practical vehicle. The former are μ-V property tests from MERCON® V, ATF+4®, and JASO M349-98, the latter is the vehicle test from DEXRON®-III. Additionally, in the evaluation of the μ-V property, there are two tests using the modified SAE No.2 friction machine and the modified low velocity friction apparatus (LVFA).

An analytic technology able to rapidly and accurately predict oil flows and churning torque in a transmission has been developed. The new method uses the finite difference method for analysis; with regard to wall boundaries it reproduces the shapes of physical objects by imparting boundary information to cells. This has made it a simple matter to treat the rotation and meshing of the gears, which form oil flows, and has also reduced the calculation cost. Tests of single-phase and multi-phase flows and churning torque were conducted in order to verify the accuracy of the new method. Calculation results for the flow velocity fields produced by rotating bodies, the trajectory of oil, and the behavior of the surface of the fluid displayed a good correlation with test results. Considering air entrainment in the oil, the ability of the method to reproduce these phenomena at high speeds of rotation was also increased.

The practical application of heat recovery using thermoelectrics requires the realization of reasonable cost effectiveness. Therefore, a thermoelectric generator (TEG) structure that can compatibly increase efficiency and reduce cost was investigated with the aim of enhancing cost effectiveness. To increase efficiency, a method of using a vacuum space structure to reduce the TEG size was investigated to enable installation just after the close-coupled catalyzer, which is subject to many space restrictions. It was found that by making it possible to use high temperature exhaust heat, power generation efficiency can be increased to approximately twice that of the typical under floor installation. In addition, coupled simulation of heat transfer and power generation using FEM, 1D cost effectiveness simulations, and bench tests were performed with the aim of reducing cost.

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).

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.

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 new DC brushless motor, which has an almost equivalent driving performance to a 50 cm₃ scooter engine, has been developed to be used in a new electric motorcycle for business. The traction motor is compact enough to be mounted close to the driveshaft of the transmission, which helps reduce friction in the drive train. Consequently, in the downsized motor, by mounting the drive train unit with the PDU (Power Drive Unit) on the wheel side by applying reduction gears, it enables the reduction of maximum motor torque requirement. It also enables other parts of the drive system to be integrated into one unit. In this motor, IPM (Interior Permanent Magnet) structure has been implemented to cope with the high rotation of the motor, and the concentrated winding stator coil has been implemented for downsizing. As for the rotor, the magnets were placed in sections and the yoke shapes were improved to achieve higher rotation speeds that provide the higher power.

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).

An electronically controlled belt-type CVT (Continuously Variable Transmission) has been developed for scooter type two-wheeled vehicles. Related to two-wheeled vehicles, the electronically controlled belt-type CVT has advantages over the conventional belt-type CVT, such as more compact and lighter weight. This was achieved by developing a new rubber belt-type. The new rubber belt-type CVT uses a rubber belt with high friction coefficient and pulleys made of aluminum. To obtain good shifting characteristics, the desired speed ratio related to throttle opening and drive speed is calculated. When moving, the actual speed ratio automatically adjusts to the desired value. For the shift modes, three shift modes, two automatic modes and one manual mode with six-speeds were prepared. The electronically controlled CVT increased the range of usable engine speeds compared to the conventional belt-type CVT. Therefore good drivability is maintained.

With a growing demand for high-power diesel engines, a key issue in engine development is to create efficient methods for developing highly durable cylinder heads, without having to repeat trial-and-error testing. Especially, it was difficult to accurately predict the occurrence and origin of cracks on the surfaces of cylinder heads in hot and cold cycle engine operation. This paper describes a thermal fatigue evaluation method developed by analyzing areas around the glow plug hole where cracks often occur during hot and cold cycle engine operation. To reveal the conditions of edges from which cracks were formed under engine durability tests, we used two procedures. One was estimating local temperature of edge areas based on material hardness determination, in order to compensate for the accuracy of the thermal analysis. The other was analyzing the strain amplitudes on the cylinder head surface using computer simulation.

Technology has been developed to increase the fatigue strength of powder-forged connecting rods. The fatigue strength of powder-forged materials was increased without adding special alloy components or lowering workability by adjusting the ratios of the conventional main mixed powders (iron, carbon, copper). In addition to solid solution strengthening of the ferrite using copper, reducing porosity, which is a material surface defect, is also an effective method of increasing fatigue strength. Reducing carbon content greatly reduced the occurrence of defects in the forging stage. The results of this research showed that the fatigue strength of high strength powder-forged connecting rods can be increased by 30% or more over that of conventional materials, allowing powder-forged connecting rods to be applied to even higher output and higher load engines than before.

A CVT for midsize vehicles was developed that simultaneously achieves high levels of fuel efficiency performance and driving enjoyment, and marketability enabling deployment to global markets, and support for high-torque direct injection engines. This was done by modifying the CVT for 2.4 L-class vehicles sold in Japan, expanding the ratio range, using CVTF with a high friction-coefficient that simultaneously realizes both high efficiency and a high transmission capacity. This enabled achievement of an overall length of 386.5 mm, total weight of 96.1 kg, and maximum transmission torque of 270 Nm, and also enhanced fuel efficiency by approximately 10% (EAP fuel economy label) compared to the 2008 model year Accord 5AT and approximately 5% (JC08) compared to the 2010 model year STEP WGN CVT. Thus, CVT performance was obtained that can simultaneously realize high levels of both fuel efficiency and driving enjoyment.

An Integrated Motor Assist (IMA) system for the 2006 Civic Hybrid has been developed, with the goal of having class leading fuel economy among compact vehicles and enhanced driving performance. The IMA system has been enhanced for greater power and efficiency. Combining the 3-stage i-VTEC engine with a higher power, higher efficiency electric motor assist mechanism enables an increase in deceleration regeneration energy and a drive mode powered by the electric motor alone. The engine is a newly developed 3-stage i-VTEC, based on the 1.3L SOHC i-DSI engine. The new 3-stage i-VTEC engine incorporates both a VTEC mechanism that switches cam profiles in low and high engine speed ranges, and a cylinder deactivation mechanism. The CVT has both an expanded ratio range and a higher final gear ratio. Through these technological enhancements, we have achieved the highest levels of fuel economy in the compact class and enhanced acceleration performance.

HONDA completed research and development of the Metal V-Belt for CVTs in-house for the purpose of reducing the minimum pitch radius. The newly developed belt is essential to the compactness of a CVT and increases the speed ratio range. Increase of ring stress caused by reducing the minimum pitch radius is treated by improvement of element shape, optimizing clearance between elements and between element and ring and improving materials.(1) In this paper, the optimization of clearance between elements, heat treatment of elements and optimization of ring material are described in detail. Optimum total clearance between elements for a virgin belt is defined by test results during operation using a specially engraved gap sensor and a telemeter system. Tolerance and conditions of heat treatment for elements are optimized concerning fatigue strength of the element nose.

This paper introduces the newly developed super sports car engine mounted in the new model NSX. A super sports car engine was newly developed to satisfy the high power performance required by the body package. Higher power and compactness were simultaneously achieved by selecting an engine displacement of 3.5 L and by using a V6 layout and a turbocharger. This enabled to mount a power train that combines a hybrid motor with a newly developed transmission in the rear of the body. The lubrication system uses a dry sump system capable of maintaining reliable lubrication in all possible super sports car driving scenarios. The combustion system uses high tumble-flow ports, a direct injection and a port injection system that increase power performance and thermal efficiency, emission reduction. To support the increased heat load due to higher power, a 3-piece water jacket is used around the combustion chamber and the exhaust ports.

For detailed temperature estimates in the engine of a running motorcycle, newly researches were conducted on the method for calculation of temperature distribution using a three-dimensional (3D) thermal conductivity simulation after calculating the total balance of heat generation and heat dissipation of the engine using a one-dimensional (1D) thermal simulation. This project is targeted at air-cooled engines in which the cooling conditions vary significantly depending on the external shapes of the engines and the airflow around them. The heat balance is calculated using the 1D thermal simulation taking into account all the routes and processes for dissipation to the atmosphere of the heat that is generated by the combustion in the engine. The 1D engine cycle simulation is applied to calculate the heat transmission to the engine from the combustion. For the calculation of heat transfer within the engine, the engine components are converted to a one-dimensional model.

By optimizing parameters related to damping performance and adopting a layout that incorporates the turbine into the damper components, a “Turbine Twin-Damper” lock-up damper was developed that achieves both damping performance and compactness. To reduce losses in the fluid flow channel, a smaller torus was developed that reduce the width of the torus by about 30%.Through the combination of this Turbine Twin-Damper and smaller torus, attenuation of the torque fluctuation transmitted to the transmission to 1/2 or less compared to a conventional product was achieved without increasing the overall width of the torque converter. As a result, the engine speed at cruise fell by 400rpm, and fuel economy improved.