The RTL250F has a compact and lightweight 249cm³, water-cooled, 4-stroke engine. As the world’s first off-road motorcycle with a batteryless electronically controlled fuel injection system (hereinafter referred to as batteryless PGM-FI system), the RTL250F has obtained the same or better racing performance than the RTL250R with a 2-stroke engine. Furthermore, the RTL250F motorcycle employs a kick-starter for engine ignition. The batteryless PGM-FI system utilizes a lower cost ECU (Engine Control Unit) integrated throttle body developed for small motorcycles. A control system was developed to obtain the drivability and usability required by a trials motorcycle. As a result, a commercially available trials motorcycle with a 4-stroke engine has been realized. This trials motorcycle has shown competitive performance for the World Championship Trials.

The 05 model US Odyssey was developed as the “King of Minivans,” providing superior styling and excellent utility combined with drivability and quality that rival any luxury sedan. It is built on the foundation of Honda safety and environmental leadership, and will become the benchmark for the next generation of minivans.

The Odyssey powertrain employs North America’s first Variable Cylinder Management (VCM) engine, achieving best-in-class fuel economy. The chassis ensures a quiet ride through the use of a floating rear subframe, and at the same time, achieves handling stability.

The interior incorporates many new ideas for the small item storage spaces required of a minivan, adopting features such as the world’s first rotary in-floor storage unit. The seats work to provide maximum utility, with the adoption of one motion stowing for the 3rd row seats, and in the eight-passenger spec, a stowable 2nd Row PlusOne Seat that can be easily fitted in the center of the second row. The power sliding doors are easily operated with the adoption of a continuous electrical supply system and touch sensors, etc.

The vehicle structure is designed to perform well in frontal impacts, offset impacts, and car-to-car collisions with the adoption of Honda’s Advanced Compatibility Engineering Body structure. In addition, the Odyssey combines existing safety features with side curtain airbags and Vehicle Stability Assist (VSA) as standard for all grades. The Odyssey is a vehicle that demonstrates Honda’s commitment to “Safety for Everyone.”

The 2005 model year ACCORD Hybrid was developed to enhance the driving performance of a V6 luxury sedan while retaining the fuel economy of a compact class, four-cylinder CIVIC sedan. The base 3.0L V6 engine has been equipped with Variable Cylinder Management (VCM) to decrease parasitic pumping losses in the engine, while motor assist has been employed to extend the operating range of the threecylinder operation mode. Both these factors have contributed to improved fuel economy. The Integrated Motor Assist (IMA) system applies new technologies to the high-voltage electrical equipment, including fine patterning of the inverter chips, as well as the use of an Interior Permanent Magnet (IPM) rotor. The result has been a 20% increase in maximum power and a 26% increase in maximum torque.

A hybrid compressor fitted with a high-voltage drive has been employed to increase the commercial appeal of idle stop. In order to offset the increase in weight from the IMA system, aluminum has been employed in the bumper beams and certain other parts to reduce weight.

All of these fuel saving technologies have resulted in a level of fuel economy, equal to that of the compact class, four-cylinder CIVIC sedan, achieving 29 mpg in US City mode and 37 mpg in US Highway mode.

A smaller and more powerful 12V DC-DC converter has been developed for Honda’s Integrated Motor Assist (IMA) system. Low breakdown voltage FETs and a beam lead diode module in combination with highefficiency soft switching circuits have reduced energy loss to increase the efficiency of the unit. Heat dissipation simulations were employed to optimize the component layout for efficient cooling. The new unit employs a digital signal processor, and the reduction in component numbers enabled by digital control has resulted in a 40% reduction in the size of the circuit board of the control section. The application of these technologies has enabled the unit volume to be decreased by 17% while output current has been increased by 60% against the former model.

For the 2005 Model year LEGEND, a compact lightweight muffler valve with new construction was developed for the variable flow rate muffler.

A conventional muffler valve rotates about a shaft.A load is applied to the rotating shaft by a coil spring.For this reason many parts are required for the valve to open and close. The body of the muffler valve traditionally coveres the entire valve operating range, resulting in the valve being large and heavy.

As a method of reducing the number of parts and the weight of the valve, this development employed the mechanism of the reed valve. A reed valve is used in 2-cycle motorcycle engines to control the intake air volume at the intake port. The addition of a support plate to the reed valve structure was investigated to suppress valve vibration and to apply a pre-load.

The number of parts in the newly developed muffler valve was reduced from 13 parts in the conventional valve to four parts. Both the weight and volume were reduced to about 1/10. This enabled the cost to be reduced to about 1/7 of a traditional exhaust valve.

A motorcycles’ smart card key system (duplex electric wave communication key system) with both, user-friendliness and antitheft certainty has been developed for the first time in the world. The system can unlock a main-switch, seat and console-box by one-push operation. The main-switch is changed to a knob type from the conventional key type. To protect the key cylinder from excess input torque, a torque-limiter was installed in the mechanism. An on/off switch that can stop the communication function at anytime was added on the smart card key because a motorcycle can be parked just outside a shop or other location when the main switch is still on and vehicle can be started. The lock and unlock available area was determined from the viewpoint of user’s convenience. The function and layout of the communication system was determined by the performance of using one low frequency transmitting antenna. A factor and an analysis technique for influences of radio noises from other electrical components on the vehicles and surrounding environments was clarified.

A method has been developed for predicting the sound radiation characteristics of transmission cases in order to reduce gear whine noise radiating from transmissions. Normal components of frequency response vectors on the transmission case surface calculated using an FE -model of the case are used to predict sound radiation characteristics. To study the validity of the method, the correlation between sound pressure level and the level of vibration of the case surface during operation and the predicted sound radiation characteristics was investigated. Results showed a good correlation between the figures and enabled equations of correlation between them unaffected by shape or type of transmission to be obtained, indicating that this method is sufficiently accurate for studying case specifications at the design stage.

This method enables the design of transmission cases fulfilling performance requirements for gear whine noise using only an FE -model of the case. The employment of the method in the development process commenced with the development of 2004 model year LIFE AT.

A propeller shaft made of carbon fiber reinforced plastic (hereafter referred to as “CFRP”), a lightweight material, was developed and used on the 2005 model year LEGEND.

To utilize the characteristics of carbon fiber (CF) which is an anisotropic material, the CFRP tube was produced using filament winding molding method. The winding angles of CF was set at 30 degrees to help ensure tube torsional strength. The press-fitting allowance of the metallic stub shaft in the CFRP tube at the joint was optimized, and adequate margin in strength and durability was assigned with respect to other metallic members to help ensure reliability.

The press-fitted portion of the stub shaft was designed such that the tube broke when subjected to the specific axial load, and the ability of the vehicle to absorb shocks during a collision was ensured.

A 30% savings in weight was achieved in the developed CFRP propeller shaft compared to the conventional steel tube propeller shaft.

A variety of components and systems in a vehicle are involved in brake judder. Up to the present, many papers have explored the roles of the brake and suspension in judder, but quite few have taken up the analysis of the vibration behavior of transfer systems, such as the steering system, subframe and body, from a viewpoint of their impact to brake judder.

This study employed bench tests to reproduce driving conditions. In order to analyze the transfer system, vibration of the entire vehicle was measured and behavior analysis was performed by visualization of vibration phenomena. Much was learned about the vibration behavior of the steering system, subframe and body, and the basic mechanism of brake judder involving the entire vehicle was proposed.

In addition, the influential factors in the transfer system were identified, and the contribution of each was analyzed.

A combustion monitoring system has been developed by applying ionic current measurement for malfunction diagnosis and combustion management of Formula One engines. In this system the spark plug’s center electrode acts as an ion probe for ionic current measurement, which eliminates the need for additional sensors. The system allows the onboard monitoring of each of the cylinders for their combustion status under all operational conditions. The accuracy and reliability has ensured that the technology can be effectively used for the management of Formula One engines with car-to-pit communication carried out via telemetering. It is capable of various types of controls including detection of misfire, hesitation, detonation and the lean-burn condition. In addition to these points, this paper reports on the relationship between the spark plug center electrode configuration and the absolute quantity of ionic current.

HILS has been introduced to the CVT ECU development process in an attempt to increase efficiency. To create HILS, it was necessary to develop a CVT HILS model capable of simulating transient states in a CVT shift mechanism, including a hydraulic control system. The calculation burden of the model was required to be low enough to enable real-time simulation. The aim of this project was to develop an experimental model capable of calculating the transient characteristics of the pulley ratio on the basis of pulley ratio, the torque input to the pulley, and the speed of revolution of the pulley; in order to enable simulation of transient states, in particular in kick-down shift. Given the high calculation load of the hydraulic control system model, test data was employed to enable the higher order simultaneous equation model to be replaced by a lower order transfer function model. The newly developed HILS has been successfully introduced to the development process for CVT ECU, resulting in a 30% reduction in the number of procedures required for verification of functioning and setting parameters for programs.

World’s first electronically controlled belt CVT System (hereinafter referred to as Honda S MATIC) for 250 cm³ class scooters has been developed in FORZA 2004 model. Honda S MATIC employed a rubber belt with a high friction coefficient and pulleys made of aluminum alloy. It was placed inside the unit-swing type engine, which is the same type as conventional scooters. For shift changing, pitch circle diameter of the driving pulley was adjusted by a motor. Preparing several selectable shift modes, suitable shifting characteristics could be obtained at flat road or mountain road. Furthermore, because of the elimination of ratio change due to aging, Honda S MATIC provides several advantages such as little reduction in maximum speed, no change in shifting characteristics, and no change in clutch connection point. Exceeding the conventional CVTs, Honda S MATIC has simultaneously satisfied low fuel consumption, low emissions, low noise and excellent engine performance.

Research was carried out on inspection technology for gear surface imperfection inspection that has the same degree of accuracy as that of a human inspector. Regarding the surface of the tooth which is the object of inspection, over-detection resulting from the extraction of uneven brightness other than that due to imperfections was an issue. For this reason, the features of imperfections that permit imperfections to be discriminated from non-imperfections were set based on visual observation. In addition, a self-organizing map which is a kind of neural network was employed as a method whereby these features are used to identify imperfections in the same way as a human inspector. By using this map to teach the inspection system the features of multiple imperfections and also uneven brightness and dirt on the surface of the gear, it was possible to recognize imperfections to the same degree of accuracy as that of a human inspector. Technology constructed using this imperfection recognition method enabled the work of visual inspection to be reduced to about 10% of that necessitated previously.

The temperature of the road surface is known to affect vehicle braking distance. This study demonstrated that the variation in wet braking distance with road temperature is significantly affected by the viscoelastic properties of the tread rubber of the tires. On the basis of this relation, a method of bench testing the viscoelastic properties of tires has been developed which enables the prediction of braking distance for a wide range of road temperatures.

The development of technology to predicting sloshing noise from a fuel tank was approached from the aspects of simulation and experiment. First, an acceleration and deceleration from a vehicle was applied to a benchmounted fuel tank containing fuel to generate a sloshing noise, and the physical parameters that were closely correlated with the sloshing noise were extracted. Next, computer simulation using an explicit transient solution method was performed to reproduce the fluid motion behavior in the tank, and a study was performed whether or not the physical parameters obtained from the experiment was useful for predicting sloshing noise. As a result, it was confirmed that the sloshing noise was caused by fuel striking localized areas of the inside wall of the tank. It was found that the occurrence of sloshing noise could be predicted by analyzing the impulsive pressure rise at the inside wall of the tank. A comparison of the computer simulation results with the experimental results showed that the experimentally observed impulsive pressure rise could be accurately reproduced by simulation as well, thus enabling the occurrence of fuel sloshing noise to be predicted.

This report describes research on the prediction of the cooling air field for air-cooled engines using Computational Fluid Dynamics (CFD). The design of the cooling air field is very important for engine cooling, a factor which has a significant effect on engine performance, fuel consumption, noise, reliability, etc. However, the flow field is very complex because a large number of components are located in the flow passages and the cooling air is generated by a centrifugal fan. In order to understand this flow field, calculations were performed using CFD and measurements were taken in an actual engine. Given practical considerations such as computing time, modeling time, correlation between calculation and test results, formulation of a database, etc., the fan P-Q (pressure vs. volume flow rate) characteristics and the flow field were calculated separately when employing CFD. In addition to visualization using Particle Image Velocimetry (PIV) pressure measurements and measurements of the P-Q characteristics of the cooling fan were employed to measure the flow field in the actual engine. The correlation between the results of CFD calculations and measurements was studied. Almost suitable prediction results were achieved by setting the P-Q characteristics at the boundary surface of the rotational area, as obtained from the calculation of P-Q characteristics, as a fan boundary condition for CFD analysis of the cooling air field. This research has enabled the qualitative and quantitative prediction of the cooling air flow of aircooled engines.

Over the past 20 years the automotive industry has constantly improved vehicle corrosion behaviour by exploiting the benefits of zinc coated steels. The application of zinc coated steel, however, does have considerable impact on processes within the automotive industry, the choice of coating type, therefore, can differ between OEM. Using the surface sensitive technique of Atomic Force Microscopy (AFM) the local corrosion behaviour of galvanised steel (GI) and galvannealed (GA) has been compared. Three sample models have been exposed to 5 wt% sodium chloride solution, for different times, to simulate cut edge, stone chipping and galvanic coupling corrosion behaviour. AFM was used to determine the volume of material loss for each time interval which could then be related to an absolute measure of corrosion rate. By converting corrosion rate to current density values the degree of electrochemical activity of the GI and GA systems were compared. For all experimental models GA showed lower corrosion densities compared to GI. The cut edge specimens show GI to have up to 7 times the current density of GA after 256 minutes. The coupled samples magnify this difference further with almost no material loss to the GA coating but a greatly increased corrosion rate for GI. This study has confirmed that, by using the specialised technique of AFM in an innovative way, GA outperforms GI, where the zinc coating has been damaged, with its coating sacrificially corroding at a slower rate.

A hexavalent chromium-free surface treatment has been developed for automotive parts which provides a coating possessing equivalent anti-corrosion performance and friction characteristics to conventional chromate layers containing chromium(VI). The treatment forms a passivation layer of trivalent chromium and metallic chelates at the interface with the zinc, while uniformly covering the surface with a protective zinc layer. It is an unusual feature of this process that a single procedure is able to form a double layer. Optimization of the amount of silica added has enabled the achievement of friction characteristics equivalent to those of conventional chromium(VI) chromate layers. The new surface treatment has resulted in a reduction in the amount of hexavalent chromium used in the production process and present in finished parts.

A rear-wheel hub with lightweight and high strength that satisfies the needs for motocross riding and contributes considerably to the vehicle mass reduction has been developed. To reduce material, a hollow structure is used in the thick section of the flange on the sprocket side of the wheel hub, which transmits driving force. The thin-wall design is employed in the straight, cylindrical section of the hub. To maintain necessary strength of the structural part, the die-casting method, which is most suitable for a thin-wall product, is applied. With regard to the casting, the inner structure quality is ensured by applying a molten metal treatment, reducing the amount of gas by evacuating the cavity and providing a squeezing function after plunger ejection. As for the material, an Al-Si-Mg alloy is employed and T5 heat treatment is applied. Thus, the yield strength is improved by 27% and the tensile strength is increased by 30% compared to the conventional material.

A low-cost material for engine exhaust valve seats has been developed with the aim of a positive use of an oxide layer. A cost reduction of more than 40% has been attained while maintaining the same or better anti-wear characteristics and machinability as current materials by the optimum designation of density, the optimum addition of secondary hard particles and the special consideration given to the basic iron powder shape for microscopic vacancy without using a special molding method such as repressing and resintering (2P2S), copper infiltration, resin impregnation, nor using a high cost material such as Cr-Mo-Co, Co, or Ni powder to improve the generation of an oxide layer.

A highly accurate method of camera calibration which works by tracing the light rays incident on the camera has been developed. In this method, the relative position of the point light source is adjusted to position the point light source image in the center of each pixel. Afterwards, the relative distance to the point light source is changed and the relative position of the point light source is adjusted again. A three-dimensional locus of the incident rays to the two point light sources obtained is then estimated from the relative positions. This procedure can be used to determine the relative positions of multiple cameras. The accuracy of the method was verified by calibrating a stereo camera and estimating the three-dimensional position of the point light source. The camera calibration method displayed identical accuracy for an image across an irregularly warped shield, which is conventionally a difficult condition for calibration, as when no shield was present. In addition, it was confirmed that there was deviation from the pinhole camera model (no crossing of incident rays).