From global environmental problems to local air pollution and traffic congestion issues, the current motorized society has a number of problems to be solved. In 1994, we proposed the concept of a near-future transport system made up of energy efficient electric powered community-use vehicles called the ICVS (Intelligent Community Vehicle System). After fabricating many prototypes, a fleet of ICVS vehicles has been in actual use at the TWIN RING MOTEGI facility since March of 1998.

This paper describes an overview of ICVS, and introduces four types of vehicles for ICVS. Additionally, it describes the details of the public demonstrations which were held at TWIN RING MOTEGI.

New working fluids more favorable for domestic air conditioning are investigated and it is concluded that new organic working fluids, namely trifluoroethanol (TFE) as the refrigerant and dimethylimidazolidinone (DMI) as absorbent are very promising. Property data for thermodynamic evaluation of these new working fluids are measured. Heat and Mass transfer characteristics for the suggested pair are also investigated in a practical aspect using laminated plate type absorber having constant curvature surfaces. The prototype residential chiller/heat pump system using the new working fluids are built to prove its feasibility.

The world’s largest four-stroke outboard motor with 115/130 PS has been developed to correspond to the growing interest in the environmental problems such as water and air pollution. By adapting the electronically programmed fuel injection system and the second order twin shaft balancer for the BF115/130 outboard motor, the followings are realized.

Environment: Exhaust gas emission level meets and exceeds the mandatory regulated values on marine engines by EPA (Environment Protection Agency), Economical feature: Improvement in fuel

consumption rate as much as 50% compared with those of existing models has been achieved, Comfort: Easy starting, excellent trolling performance, and low vibration level has been achieved.

The reduction in cost has been achieved as well as high performance and excellent reliability through utilizing mass-produced automobile engine parts for HONDA ACCORD series and frame parts from an existing outboard motor.

Under the concept of “New Generation Real Open Sports”, a two-seater open sports car the HONDA S2000 was developed.

Applying the newly developed technologies below, the S2000 became a roadster with needs of the time, for example environmental protection, safety and comfort, as well as “fun to drive” that is the origin of sports car.

· The engine-layout behind the front axle that enabled weight distribution ratio of 50:50 for front and rear axles, lowered the center of gravity, and reduced the yaw moment of inertia.

· The open body, whose weight, body stiffness and crash safety performance are equal to those of closed body by the measures such as higher floor tunnel with a box shape section.

· The 2L L-4 engine that offered high power of 125PS/L and low exhaust emission levels half of the 2000 Japanese regulation.

· The 6-speed manual transmission that matches well to the input of 9 000 rpm and offers a light and smooth shift feel.

· The wind management technology and heater performance that make driving with the top opened comfortable even in winter.

2 liter DOHC-VTEC engine was developed for the HONDA S2000. It produced the highest power-output as a naturally aspirated 2 liter mass-production engine. At the same time, it also achieved a half of the emission level of 2000 Japanese exhaust emission regulation (J-LEV).

The new engine utilized a newly designed VTEC cylinder head, new construction cylinder block, cam-shaft chain drive system, metal honeycomb catalyst and many other new technological elements. This paper describes the major specifications, general construction, technological features, power-output, and exhaust emission characteristics of the engine.

HONDA S2000 has been developed with the key words “New Generation Real Open Sports”.

It provides with the newly developed 6-speed manual transmission which is expected to show supple feel of shifting with the extremely short transmission shift stroke 36mm while the higher engine revolution 9000rpm,which is unprecedented in the mass production cars, is available.

The IOR (Independent Output Reduction gear train) is employed in order to substantially reduce the equivalent inertia mass of synchronizer and allow the ultimate engine revolutions.

The construction of highly rigid transmission case allows the shift knob to be stiff and well control of vibration occurrence.

Consequently the basic construction of FR transmission has been successfully improved to the development objective.

The new open monocoque body was developed to meet the concept of the HONDA S2000.

Large amount of additional weight was required to maintain the performance of body rigidity and crash safety of an open-body equivalent to a closed-body.

The new monocoque body, named High "X" Bone, was designed to have a closed floor tunnel section, which laid at the same height as the front and rear side members.

This enabled us to get better performance of body rigidity and crash safety than closed-body with the same weight level.

With the theme of “Comfortable driving, and ‘being one’ with the vehicle”, the chassis of the HONDA S2000 has been developed with an aim at a real sports car that has smooth and light handling characteristics.

For comfortable driving, the engine was positioned behind the front axle to reduce the yaw moment of inertia as well as proper distribution of the weight between the front and rear. The suspension was designed to be high in lateral stiffness. The size of rear tires are wider than the front tires so that they track well with the fronts.

The toe angle control, most suitable tire characteristics and improvements in aerodynamics make the handling characteristics highly stable in all driving conditions.

An important theme during the development of the “New Generation Real Open Sports” HONDA S2000 was to create a pleasant cabin feeling during open running conditions by controlling the wind flow in and around the cabin area, and also managing the performance of the heater/air-conditioner unit. These open running objectives were realized through the application of the following 3 items.

1) The shape of the rollover bar decreased the level of back-draft wind, while the A-pillar shape aids in the management of the frontal wind flow along the windshield.

2) A pleasant level of wind flow was achieved in a variety of open running conditions which contained a high speed region through the use of an aerodynamic wind screen.

3) A good level of heating distribution and overall heating feeling was attained during cold temperature conditions. This was achieved through the use of a new heater distribution method called “OPEN mode”.

Large amount of efforts are put into the research of the secondary O₂ feedback that is the feedback control of air fuel ratio according to O₂ sensor output for increasing catalyst reduction rate.

The robust stability against the modeling error, which is caused by nonlinear characteristics of the catalyst, is necessary for improving the control performance.

Low-pass filer model was developed based on frequency characteristics of the catalyst, and Adaptive Sliding Mode Control was applied to that feedback algorithm. As a result, this secondary O₂ feedback obtained the superior stability against the modeling error.

To warm up catalyst quickly has an effect on emission reduction during engine startup mode, to give an example, a method using ignition retarding is generally known.

In this investigation the quick warm-up system was put into practice by the logic which much intake air was guided into the cylinder using feedforward control, and engine speed was controlled by ignition timing.

In addition this method had need to prevent deterioration of control with variations in air-device flow. Therefore it had been able to advance performance by means of compensation for the mass flow rate using an Adaptive Sliding-mode Controller and learning coefficient of compensation for the mass flow rate.

The new valve control system (HYPER VTEC: Variable Valve Timing and Lift Electronic Control System) with a valve inactive mechanism has been developed to achieve effectively engine power enhancement and the environment protection for sports type motorcycle engines with higher engine speed.

The mass increase in the valve operating system is kept to a minimum with a compact, simple mechanism, enables high engine speeds of up to 13,500 rpm without malfunctional valve motion, and providing high reliability and durability.

In addition, the valve control system contributes to enhance fuel economy and also to decrease the intake and exhaust system sounds during two valve operation. The switching mechanism part of the operating valve number was manufactured by cold forging, and was achieved inexpensively.

This system was introduced on the sports type motorcycle CB400SF for domestic sales in 1999.

Earth environmental problems cause regulations to enforce or propose emission reduction and fuel economy improvement in many countries. Under such conditions, authors developed a new engine for reducing emission and maintaining high power output by improving the exhaust system as well as the combustion, A/F control and the catalytic converter.

The exhaust system comprises the 4-into-2 exhaust manifold of low heat capacity, which is preferable to high power engine due to exhaust pulsation, shortens the time necessary to activate the catalytic converter and can make the catalytic converter to be installed under floor.

Developed exhaust manifold is characterized by a double wall structure with an inner thin wall and a slide structure for absorbing heat expansion difference between both walls.

A continuously variable transmission, or CVT, offers high fuel economy, presumably because it can produce a low BSFC driving condition with its continuously variable ratio characteristics.

In this paper, it is shown that a substantial amount of work loss is generated in the drivetrain, including the transmission and engine accessories, from the engine to tires. It is also shown that focusing solely on BSFC values is not sufficient.

Based on the statement above, fuel consumption was targeted as a new index to indicate the overall efficiency for the engine, engine accessories and transmission. Integration of the engine-CVT control system and new algorithm to calculate the combinations of engine torque and CVT ratio to minimize the overall fuel consumption is proposed.

Furthermore, as a result of the tested vehicle that incorporates the integrated system described above, the system achieved an approximate 1% improvement in fuel economy in the LA-4 mode test compared to the conventional system and also reduced control data set up time by the use of CAE tools and simulation.

It is very important to grasp the forces acting on the layered rings of a metal pushing V-belt for estimating the durability of the V-belt.

In this paper we measured the ring stress of the outermost rings each time another layer was added. By estimating the distribution of the ring stress and the ring tension for the layered rings from the outermost ring stress, we deduced the following conclusion. The forces acting on the innermost rings were higher than the other layered rings. Therefore the durability of the V-belt can be estimated from the durability of the innermost rings.

A new steering system which has variable gear ratio according to vehicle speed and steering wheel angle has been developed.

As the steering gear ratio in existing automobiles is almost constant, yaw rate gain increases with increasing vehicle speed. Moreover, for understeer vehicle, yaw rate gain tends to decrease with increasing lateral acceleration.

With a view to improving the driver-vehicle response, to make the yaw rate gain almost constant, a steering system in which the equivalent steering gear ratio increases with increasing vehicle speed and decreases with increasing steering wheel angle was created.

This paper presents the procedure for selecting variable gear ratio characteristic, starting with a hypothesis of ideal gear ratio which was derived from observations of drivers' steering behavior, including the compensation of the gear ratio for vehicle speed and steering wheel angle, and the estimation of the effects of the gear ratio by simulation.

This paper also introduces the design method and the construction in order to realize the selected gear ratio, the effects that were confirmed by vehicle tests, and the vehicle characteristic which this system necessitates.

Transient vibration such as steering kickback in automobile suspension is a technical problem whose cause-and-effect relationship is not well known and for which design guidelines have not been established yet.

In order to investigate such a phenomenon, the authors tried a new method in which the individual contribution of force vector components to the steering tie-rod axial force was examined. These force components and their contribution were calculated from the measured force vector components and the measured acceleration vector components. The method was applied to investigate the causes of steering kickback, and some key design points were found.

In order to minimize the occupant injury in a vehicle crash, we tried an approach to address this issue by making the wave form of vehicle body deceleration optimal to lower the maximum value of the occupant deceleration.

A study with a one-dimensional two mass model was done to address the kinetic mechanism between the body deceleration wave form and the responding occupant's motion while finding a mathematical solution for the optimum body deceleration wave form. A common feature of the three derived mathematical solutions is that they consist of three parts, a high deceleration, a negative deceleration, and a constant deceleration. We have demonstrated this by simulation using a three-dimensional dummy. The results show the response of the dummy closely agrees with that of the one-dimensional two mass model, thus the mathematical solution adequately proves this and the occupant injury has also been reduced.

Honda considers that a positive aspect of airbags for motorcycles would be to reduce rider ejection speeds through airbag installation and to minimize injury of riders caused by hitting other vehicles in traffic accidents. This study covers the exploratory stage for airbag research, and the airbag system was evaluated by full scale impact tests and computer simulation according to ISO13232.

The airbag system is made up of a inflator, an airbag, acceleration sensors and ECU, and was installed on a GL1500 motorcycle as test.

The evaluation results indicated the prototype airbag had both some potential benefits and adverse effects in certain impact tests. The risks when measured against the benefits of prototype airbag were larger than for cars. Full scale impact tests of 9 collision configurations and computer simulation of 200 collision configurations indicated 25 % and 16 % of risk, respectively. Further research is necessary to reduce the risks.

Using a current simulation model representing the dummy's foot by ellipsoids, it was difficult to accurately predict the foot motion rolling off of different surfaces at varying heights from the toeboard surface. A new modelling method using Facet Surface, which is a newly developed function in MADYMO program, was applied to the dummy's foot. Furthermore, properties of the Hybrid-Ⅲ foot and ankle revised by NHTSA were measured and reflected in the model.

A sled test, in which the dummy's left foot rolled off the foot rest, was conducted to validate the model. When comparing the simulation results with the sled test results, high accuracy for both the dynamic motion of the foot and the tibia moment were confirmed.

CNG or LPG fueled engines typically have less valve seat wear resistance than gasoline powered engines.

An analysis of the valve seat wear mechanism was performed and various designs of alloys were studied. A Co-Mo-Cr type alloy, that has a self-lubricating effect against wear, was employed. Also, MnS addition improved the alloy’s machinability, which is typically counter to a materials wear resistance characteristics.

In the end, a robust CNG/LPG engine valve seat material specification was successfully developed that exhibits equivalent wear properties to that of gasoline powered engines.

In order to develop the new 2L DOHC engine for the “New Generation Real Open Sports” HONDA S2000, it was necessary to develop an improved valve rocker arm which allows for extremely high engine revolutions and is light in weight while compact in size.

The new valve rocker arm is characterized by applying roller bearing to the cam follower and variable valve timing and lift electronic control system (VTEC) built-in (or coaxial) roller bearing shaft. It also is capable of mass-production by employing metal injection molding (MIM), which will produce near-net shape rocker arms.

With these improvements, the new engine has been successfully developed and achieves a maximum revolution of 9 000 rpm.

Previous high impact resistant polypropylene for instrument panel was mainly paintend. Because it was difficult to have high quality of aPPearance. But it is required to eliminate painting for commercial competition.

In this paper, we modified dispersion and particle size of elastomer added to polypropylene for low gloss surface, hardness and contents of elastomer added to polypropylene for scratch resistance and shape of filler for inhibition of weld-line. At this method , we developed new non-painted material for instrument panel which has both high impact resistance and high quality of aPPearance.

This paper includes the report on the development of small-scale production method for large-size exterior plastic parts of vehicle when it was applied to the production of the pop-up roof specification of specific vehicle.

The RTM (Resin Transfer Molding), which is conventionally applied to a small-scale production in a development, was not applied to the production of large size exterior plastic parts which requires high grade quality.

To use RTM, we tried to:

(1) employ after-cure to produce in high accuracy,

(2) use parts which are produced without mold as many as possible to reduce investment,

(3) use rectangular extruded aluminum hollow beam, formed styro-foam core material and hybrid pre-form material to make products light and stiff, and

(4) use fine glass fiber filled FRP (Fiber Resin Plastic) to increase the strength.

These measures have resulted in great reduction of investment and cost. Also, many parts of FRP are jointed by bonding so that after used up, they are capable of group collection to be recycled.

In order to get good quality for car interior molding plastic parts,we investigated about die, plastic material and molding condition to reduce gloss of plastic parts.After that we got the low gloss plastic parts.

Then we found reason of increace gloss during mass production was caused by additives of plastics.And we got the low and stable gloss plastic parts by changing of additives of plastics.