In the shrinking of sedan market, the creation of new values for sedan is strongly demanded. The luxury sedan, LEGEND, comes to the situation of a full model change after the interval of nine years. The 2005 model year LEGEND has been developed, which has the aim of creating the ultimate luxury sedan brand of Honda and the attractive features expected to the luxury sedan class.

A good balance between excellent driving performance and fuel economy has been achieved with lightweight and compact engine which has superb power performance, the weight saving technologies, and SH-AWD to improve the driving stability dramatically. The vehicle features the latest technologies such as iNVS and AFS, driving support system to increase safety during night driving, and the latest safety equipments to reduce impact. The functional design of spacious cabin, which appeals to the senses, and quietness in a cabin during driving present a driver and passengers with a relaxed and luxurious experience. These advanced technologies have been brought together in an ultimate sports sedan, the new LEGEND, which has new values and attractive features of “high quality as a luxury car” and “driving pleasure”.

In a world first, Honda has developed the SH-AWD (Super Handling-All Wheel Drive) system, enabling complete control of torque distribution to any wheel, front or rear, left or right.

A direct electromagnetic clutch in which solenoid attraction acts directly on the clutch was newly developed to enable the system to be realized. In addition, a 2-speed shift unit was developed to adjust differential revolutions in the clutch in order to enable the system to exert control under all conditions.

The use of this system in a vehicle provided incredibly neutral steering and high vehicle stability by direct control of turning yaw moment through differential distribution of torque to the right and left wheels. And the vehicle has enhanced cornering limit performance by equalization of the load ratio between the wheels through differential distribution of torque to all four wheels.

An aluminum hood was developed for the 2005 model year LEGEND in order to reduce costs while maintaining durability and performance requirements and help ensure pedestrian safety.

We focused on materials cost reduction for the aluminum hood skin sheet by reviewing its chemical composition and developing a 5000 series alloy produced with the continuous casting directed rolling method for the stiffener sheet.

Planning for general purpose processing specifications, a PVC-free acrylic acid resin system mastic sealer for steel and aluminum was applied for adhesion between the various components. Continuous multipoint self-piercing rivets were applied for the reduction of machining costs. The surface was treated with a surface conditioner that has a zinc phosphoric crystal as its main component. This allowed the precise formation of a chemical conversion coating on the surface.

The frame structure of this developed hood was also optimized, enabling it to achieve the same performance in pedestrian safety as a conventional steel hood.

The first aluminum subframe has been developed in the world, that is composed of bulge-formed members and die cast members welded by MIG.

The bulging employed a newly developed hot process with superior formability together with an alloy developed for the hot process. The die casting employed a newly developed vacuum die casting process and alloy which has superior weldability. A method of MIG welding was established, after the weldability of these new alloys was researched. The developed subframe achieved a 20% cost reduction and 10% weight reduction while keeping functional performance equal to or better than the company’s conventional aluminum subframe.

Change to the use of aluminum material is being promoted in order to achieve the important goal of weight reduction. However, the high cost of this material means that weight reduction by this method is currently not progressing. Here we focused on the material cost, which occupies 59% of the manufacturing cost of forged aluminum suspension arms, and developed a new continuous casting technology which does not need peeling. This is called the peeling-less casting billet. To eliminate the peeling process, it was necessary to control material segregation and surface unevenness. Therefore the material content was adjusted (adding Ca) and direct cooling during casting was used, together with adiabatic mold casting and a graphite casting mold, and those problems were overcome. This developed technology eliminated the need for peeling, and in combination with reduced costs due to equipment depreciation, it reduced the cost of forging materials approximately 20%, thus realizing a reduction in cost compared to conventional forged aluminum suspension arms.

Honda R&D has developed an advanced business jet. The HondaJet is an entry-level, light-weight, business jet featuring an extra large cabin, high fuel efficiency, and high cruise speed compared to existing small business jets. To achieve the performance goals, a natural-laminar-flow wing, a natural-laminar-flow fuselage nose, an over-the-wing engine-mount configuration, and other advanced technologies were developed. The wing is metal, having an integral machined skin to achieve a very smooth upper surface, which is required for natural laminar flow. The fuselage is made entirely of composites and the stiffened panels and the sandwich panels were co-cured integrally in an autoclave to reduce weight and cost. The advanced avionics system, which provides a high degree of integration for enhanced functionality and flight safety, was also installed in the cockpit. Several advanced technologies were employed for the HondaJet.

HondaJet utilizes an all-composite fuselage. The main feature of this fuselage structure is that the stiffened panel and the sandwich panel are co-cured integrally to reduce both weight and cost. Another key feature is that a buckling tolerance design is adopted for the skin. This means that shear buckling is allowed beyond 50% limit load. Several affordable process technologies were developed in the field of lay up and structural bonding. The material and structural tests were conducted applying the concept of “Building Block Approach” to prove safety of flight. First the design allowables of the materials were decided. Environmental, damage tolerance, and fatigue conditions were considered. Three major component tests were conducted.

Honda’s current inverter generators have a maximum power of 3kVA and single-voltage output. Dual-voltage output is essential when producing higher-power inverter generators, because the larger equipment connected to them requires either high current or high voltage. A new dual-voltage inverter has therefore been developed. The dual-voltage inverter produces two voltages by connecting two inverters in parallel or in series. Sub-winding for the inverter unit power supply has not been employed in the alternator. Only main winding has been used, and power supplies have been built into each unit, meaning that the system is composed of the output of the main winding. This has enabled the alternator to be reduced in size and increased in efficiency. The completed generator is fitted with an integrated control unit. The centralization of control functions has enabled 2/3 of the electronic components to be eliminated and a liquid crystal monitor to be employed to display information. Like Honda’s previous inverter generators, the newly developed EM7000is employs an electric governor. In combination with its shroud sound isolation duct structure, this enables the unit to run quietly with high fuel efficiency.

A 4-stroke, 150 cm3 engine that satisfied both of low fuel consumption and drivability was developed for Brazilian market. For decreasing the fuel consumption, quick burnning was attempted by employing a tumble-port, and leaner air-fuel ratio than the former model was enabled. In order to decrease the engine friction, a thin oil ring and a cam follower with a roller bearing was employed. Engine output at low and middle engine speed was enhanced and high gear ratio was enabled. This reduced the fuel consumption at the same vehicle speed. As a result, compared to the former 125 cm3 models, the fuel economy at ECE-40 mode was enhanced by 18% despite increased displacement to 150 cm3, and the maximum output was increased by 18%. Engine output at low and middle engine speed was enhanced by 37%. Emission level of EURO-2 was attained without any devices such as secondary air induction. In addition, vibration was decreased with a primary balancer.

A center injection system in which a high-pressure fuel injector is located in the center of the combustion chamber has been employed in a direct-injection engine, significantly improving fuel economy and emissions performance in the direct injection stratified charge (DISC) range. Ensuring the stable formation of a combustible mixture around the spark plug at the appropriate time is the most important element in achieving stable combustion in the DISC range. During the development of the engine, a variety of methods were used to measure mixture distribution, including visualization using Laser Induced Fluorescence (LIF) and infrared absorption analysis to measure the air-fuel ratio around the spark plug, and CFD simulations were conducted to analyze mixture distribution and in-cylinder flow, enabling analysis and evaluation of the combustion process. These analyses enabled the design of an original piston cavity form with reference to the fuel spray characteristics of the center-positioned high-pressure injector. This has ensured the stable formation and maintenance of a compact combustible mixture around the spark plug, enabling the achievement of a high lean combustion limit in stratified combustion and significantly reducing fuel consumption.

A new electronically controlled 4-speed automatic transmission has been developed for use in next-generation compact class vehicles and employed in the new Honda LIFE. In addition to new fourth gear shift and lock-up mechanisms, the new AT features a parallel triple-shaft structure with a squashed torque converter and a case with no side cover, and the control system components are also concentrated. These have made the unit more compact, the shortest in its class at 334 mm in overall length. The employment of Active Lock-up II to provide lock-up control has significantly increased the lock-up control area with no loss of drivability. In combination with the addition of a fourth gear and the reduction of friction by 30%, this expansion of the control area has contributed significantly to improved fuel economy.

In addition, the employment of direct control of clutch hydraulic pressure using a linear solenoid, center positioning of idler gear trains on each shaft and climbing and descending control, among a variety of other technologies, has resulted in a smooth and very stable shift feeling, superb quietness and improved drivability.

A 2.4L class CVT has been newly developed for the 2004 Odyssey to provide superior automotive fuel economy and a high level of driving pleasure. In addition to a torque converter, a first for a Honda CVT, the new CVT includes among its features lock-up control operating from immediately after start-off, a high-efficiency oil pump with a delivery switching mechanism, technologies enabling overall length to be reduced, a simple hydraulic circuit capable of optimizing pulley pressure, an ECU to realize excellent driving performance and a three-part case. With a maximum transmitted torque of 218 Nm at 385 mm in length and weighing 95.3 kg, the new CVT records 7.5-11% higher transmission efficiency than competitors’ CVTs in the same class. The new CVT has enabled optimization of shift control, balancing fuel economy with sporty driving performance.

Honda presently mass produces a metal pushing V-belt to enable a compact CVT layout in a 1.5L class vehicle. The project discussed in this paper based itself on the technologies developed for mass production of the 1.5L class belt, and employed dynamic analysis of slack string elements and study of ATF extreme pressure lubricant oil films using measurements of electrical resistance to develop a metal pushing V-belt enabling a compact CVT layout in a 2L class vehicle.

The size of CVTs has conventionally been determined by the pitch radius of the V-belt. To increase the torque capacity of the CVT, it was formerly necessary to increase the pitch radius of the belt in order to reduce the belt load. In the newly designed belt, reduction of the pitch radius has enabled the distance between the shafts to be reduced, hence reducing the size of the CVT. The newly developed belt achieves a maximum transmitted power of 150 kW with 170 mm between the shafts, and enables a more compact CVT layout.

An optimization method has been developed as a tool to contribute to the design of lightweight and high-rigidity automotive transmission housings. The method is divided into topology optimization and shape optimization and can be applied at any of three different stages depending on the maturity of the design.

The application of topology optimization from the framework conception stage in the design of an actual automotive transmission enabled rigidity targets to be met with a reduction in weight of 10%.

Study of the generation of stress in the optimized shapes predicted by the method indicated that the placement of ribs along the paths of transmission of bearing load to increase rigidity was highly efficient.

Fatalities in rollover accidents have recently been increasing in the US. In particular, 60% of fatalities in SUVs are related to rollover accidents. In addition, 62% of occupants who die in rollover accidents involving all passenger vehicles are either partially or completely ejected from the vehicle. To help address this issue, a side curtain airbag system has been developed that enhances occupant safety in rollover accidents. When a rollover sensor detects the possibility of the vehicle rolling, the side curtain airbags are deployed, covering the greater part of the side windows and thus reducing the possibility of occupant ejection.

In the field of collision safety, conspicuous progress has been made in recent years in occupant restraint devices. Collision avoidance and injury mitigation technologies are also developing rapidly. Various proposals have been made for next-generation systems combining collision avoidance technologies with injury mitigation and occupant restraint technologies. This paper introduces a first step in this direction, the Honda precrash safety technology employed in the Inspire.

The newly developed 2.2L 4-cylinder diesel engine for the new ACCORD marketed in Europe employs numerous noise and vibration reduction technologies. 2nd-order vibration balancers and other technologies have been used to reduce engine noise and vibration, and optimization of pilot injection has reduced combustion noise. In addition, a principal axis of inertia type engine mounting system with torque rods has been employed, and soundproof performance of complete vehicle has been improved.

The new ACCORD using this new engine is powerful yet achieves the high quality cabin sound and low vibration levels, and has been extremely well received in the European market.

The EURO-3 emission regulation will be enforced in the EU in 2006. To meet the regulation, emission reduction technologies were developed by using a test motorcycle with a water-cooled, four-cylinder, 1 100cm³ engine. In order to reduce HC during cold-start cycle, catalyst was activated early and the fuel spray was atomized by means of combining Idle Air Control Valve System (IACV) with ignition retard. In order to reduce NOx during extra-urban driving cycle, number of cells and capacity of three-way catalyst were optimized, and air-fuel ratio was also optimized. However, the increase of catalyst capacity caused increase of exhaust resistance, and reduced engine power. In order to solve this problem, location of the catalyst was optimized. By these measures, the EURO-3 regulation value was sufficiently attained without detriment to the engine power and drivability.

Honda has developed its first-ever i-VTEC I direct injection gasoline engine employing a center injection system in which a high-pressure fuel injector is located at the center of the combustion chamber. Direct injection enables stratified charge combustion to be employed, and the new center injection engine demonstrates significantly improved fuel economy and emissions performance in the range of vehicle operation in which this type of combustion is used. The authors studied methods of switching between direct-injection stratified charge (DISC) and pre-mixed combustion in order to utilize DISC. The two forms of combustion employed in the new direct-injection engine differ in terms of combustion limits in relation to recirculated exhaust gas and air-fuel ratio. This causes the torque difference which is a specific issue in direct injection gasoline engines. The authors resolved this issue through the application of two technologies. Fuel injection during the intake stroke and the compression stroke has improved the combustion limit. When combustion is stable, the appropriate quantity of fuel to be supplied is determined from the required torque.

In fall 2003, Honda introduced a passenger vehicle diesel engine to the European market. During the development of this engine, research was conducted on combustion technologies to reduce fuel consumption, combustion noise and emissions.

By adopting the pilot injection while also advancing the start of main combustion event, fuel consumption and combustion noise are both lowered, but emissions performance was not improved. Dispersion of the air-fuel mixture and the extension of the appropriate period for dispersion ensured a lean local air-fuel ratio and resolved the emissions issue.

The use of these combustion technologies has enabled fuel consumption and emissions out of engine to be reduced with no increase in combustion noise. Fitted in a 1 590 kg equivalent inertia class vehicle in combination with the catalyst, the vehicle satisfied the 2005 European diesel exhaust emissions standards (EURO IV), and achieved a low fuel consumption of 5.4L / 100 km and superb quietness.

Accurate engine speed control has been required to improve the shift quality of automatic transmissions. However, engine dynamics dramatically change with engine load and with the aging of the engine. Therefore, conventional controls such as PID control cause large overshoots and can not ensure accurate controllability. A control composed of a sliding-mode controller and an adaptive disturbance observer was therefore designed and applied to engine speed control. The new control had high robustness against changes in engine dynamics and excellent ability to suppress overshoot. In addition, it provided accurate and rapid engine speed control under all engine conditions.

Sliding mode algorithms are highly responsive and robust, and this has led to their use in air-fuel ratio control and device control systems. Alteration of the gradient of the switching line enables their ability to suppress disturbance to be freely set, but no applied research has been conducted on this characteristic. In this research, the ability of a sliding mode algorithm to suppress disturbance was lowered to enable the construction of a high-compliance servo control system, and this was employed in shift control in an automated manual transmission, in which compliance control is required during shifting. The sliding mode algorithm has been employed in position control to ensure contact between the sleeve and the synchronizer ring and force control to enable the synchronization of the revolution of the main shaft and counter-shaft through sleeve force. The compliance established between the sleeve and the synchronizer ring by this means has enabled the formerly required mechanical buffer to be eliminated, and shift time has been increased to 350msec. In addition, the stabilization of sleeve force has suppressed bouncing and stoppage of the sleeve and failure of the synchronizer ring during shifting.

The elimination of the throttle has recently attracted attention as a means of improving fuel economy through the reduction of pumping loss. The research described in this paper concerned fuel economy, noise and vibration performance and wide-open throttle performance in an engine equipped with an electromagnetic variable valve timing mechanism to enable the throttle to be eliminated.

A high-efficiency mechanism equipped with a low voltage drive method from considerations of practical use and constant voltage opening and closing control that has realized short and stable valve contact speed were developed. In comparison with a conventional cam-driven valvetrain, this new valve mechanism has achieved a simulation-based improvement of 7% in fuel economy in the 10.15 mode and a roughly 20% increase in torque at low to mid engine speeds through optimization of valve timing and scavenging effectiveness. In addition, the combination of compact type-integrated hydraulic tappet, dual over-excitation constant voltage control and resin engine cover, has enabled the engine to record the same noise level when idling as an engine with a conventional valvetrain.

In motorcycle engines, blow-by gas is generally introduced into intake system including air cleaner to decrease blow-by emission inside crankcase. There was concern in the previous system that some running conditions might shorten an interval of oil change. Those phenomena were caused by mixing of water or gasoline in the blow-by gas into engine oil. In order to control the phenomena, a new positive ventilation system of the crankcase was developed. In the new system, fresh air was introduced into the crankcase by pressure fluctuation in the crankcase. The fresh air ventilates the crankcase. Comparing to the previous system, the developed Positive Crankcase Ventilation system has decreased the density of the water and the gasoline contained in the engine oil: water by 73% and gasoline by 42%.

This paper describes the development of an 0W-20 engine oil meeting the ILSAC GF-4 engine oil standard which will go into effect from July 31^st, 2004.

The GF-4 engine oil standard stipulates upper limits for phosphorus and sulfur content in oil to prevent poisoning the exhaust system components, but the new standard has generated concerns about the acceleration of wear of engine parts. Each additive in the newly developed has been selected to improve anti-wear performance. In addition, the contribution of kinematic viscosity and HTHS viscosity to engine motoring friction has been verified, and the molecular weight of the viscosity index improver has been optimized to achieve the higher fuel economy requirement in GF-4.

The newly developed engine oil was evaluated in GF-4 standard tests and was confirmed to meet GF-4 performance.

To date, fixed volume tank pressure measurement devices have been employed in evaluation of the performance of the gas generators (inflators) used in airbags, etc. However, these measurement devices cannot be used to accurately gauge inflator characteristics as the volume changes. This research project therefore built a variable volume tank pressure measurement device⁽³⁾ to enable measurement data to be obtained as internal volume changes with increasing tank pressure. This device was used in tests, and measured values were input into a predictive equation to define an index (inflator work) for the evaluation of inflator performance. The new measurement device has made it possible to evaluate energy in an inflator and has enabled the development of a new performance evaluation index (inflator work) and method.

A high-ductility TRIP steel sheet has been developed to achieve weight savings in automotive bodies. When TRIP steel is deformed by pressing, etc., the transformation of the retained austenite distributed in its matrix structure into martensite controls the strain concentration. This gives the material higher formability than other steels. However, TRIP steel sheets contain a higher amount of Si than standard steel sheets, and this can cause the platability of the material during hot-dip galvanealing and the ability of cold rolled sheets to accept coatings to decline. A TRIP steel displaying the required strength and formability while possessing identical platability and coatibility to standard steels has therefore been developed by optimizing the amount of C, Si and Mn, the main constituent elements of the steel, adding an element which controls Si concentration to sheets for hot-dip galvannealed (GA steel sheet) and removing the concentrated Si surface layer of non-galvanealed sheets for cold rolling (CR steel sheet). As a result, it has been possible to achieve an identical level of formability in 590MPa and 780MPa grade steel sheets when compared to 440MPa and 590MPa grade standard high strength steel sheets (HSS) respectively. In addition, the new steel possesses identical energy absorption characteristics to existing high-tensile steel but is 10% lighter, enabling weight per vehicle to be reduced by more than 10kg when the new sheets are employed.

A ferrite-pearlite type microalloyed steel has been developed for use in the crankshafts of small multipurpose engines. Although the thermal refining process after hot forging has been eliminated, this steel possesses equivalent strength and toughness to thermally refined steel, and can also be induction hardened. The design of the alloy sought to ensure toughness by increasing the ratio of ferrite in the structure of the steel and refining the structure through the use of intragranular ferrite and, at the same time, to ensure strength by strengthening of solid solution and precipitation strengthening and increasing hardenability while still employing a carbon content within the range enabling induction hardening. In addition, conditions for the temperature of heating during hot forging and for cooling after hot forging were established to control coarsening of the structure and optimize the characteristics of the alloy. At the same time, the design ensured that while no lead was added, a level of machinability equivalent to that conventional free-cutting steel with added lead was achieved. This has reduced the cost of crankshaft manufacture by eliminating the thermal refining process and done away with the necessity of adding lead, an environmentally harmful substance.

A numerical methodology that decomposes a fluid motion into the convection due to the flow material velocity and the transportation of the sound wave was newly developed and then a unified flow solver for all-speed flow regime was conducted. The developed flow solver has been validated using bench mark problems. Furthermore, the solver has been extended to practical one for an engineering purpose, such as three-dimensional turbulent flow, by implementing an unstructured grid method, a parallel computation technique, and a turbulence model. Availability as a unified flow solver in practical use has been confirmed by solving a flow field around three-dimensional wing.

A rather novel coupling method is developed for predictions of aerodynamic sound fields. The flow fields are predicted by Reynolds Averaged Navier-Stokes (RANS) and the sound propagations are computed by Linearized Euler Equations (LEE). This method enables wide range aeroacoustic analyses with the lower computational cost. All simulations are performed using unstructured grid methods because of their flexibility to fit complex geometries. To validate this method in the present work computational aeroacoustic analysis around an airfoil was carried out. Sound sources are treated universally by using turbulent vortex fluctuations which induce aeroacoustic phenomena, not by the secondary pressure fluctuations on the body surfaces. This suggests a new guidance in computational aeroacoustics.

Identifying sound sources which make a significant contribution to pass-by noise is essential in attempts to reduce it. This paper discusses a technique of identification of sound sourse using the inverse matrix method.In this technique, multiple observation points are established around a sound source, and the sound source is identified using sound pressure and acoustic transfer function. The stability of the inverse matrix of the acoustic transfer function has a significant effect on the accuracy of sound source identification. An index expressing the stability of the inverse matrix of the transfer was therefore devised. The use of this index has made it possible to determine optimum observation points. Actual vehicle tests have confirmed that the method is capable of predicting far-field sound pressure with a high degree of accuracy.

Pulse feeling is an important factor of ride comfort for V-twin engine, American-type motorcycles. Depending on sensory evaluation, the pulse feeling varies widely among estimators. Therefore, it takes much time to determine specifications. To solve this problem, a quantitative evaluation method was developed. In the development process, sensory evaluation testing for Japanese and American riders was conducted to verify how they feel the pulse. There was no significant difference between both riders. Both riders felt that the seat vibration made the largest contribution to the pulse feeling. In order to quantify the seat vibration pulse, a pulse intensity indicator was added to the previous sensual vibration indicator. Furthermore, time domain response analysis was applied to a complete motorcycle analysis model. The output showed good correlation with the actual data. The pulse feeling indicator was obtained from the analysis results. Consequently, the established method has allowed early prediction of the pulse intensity at design stage.

A measurement standard model of buttocks shape was made. This model represented average body pressure distribution of Japanese. The distribution data of Japanese, American and European were measured, and compared by using Buttocks Characteristic Index. The pressure body distributions for every category of motorcycle seats were measured by using the measurement standard model of hip shape. Relation between the measured distribution data and the fit feeling evaluation was analyzed. Based on the analysis, a prediction equation of fit feeling was devised. A simulation model of body pressure distribution was created using Finite Element Method. The simulation model was substituted for the measured distribution data in the prediction equation. A prediction method of fit feeling has been established. The established method has allowed early prediction of the fit feeling for motorcycle seats at the designing stage.

The concept of Honda airbags for a large touring motorcycle is “To reduce the injuries of rider impact with opposing vehicle and/or opposing object in frontal collisions by absorbing rider kinetic energy and by reducing rider velocity separating from the motorcycle in the forward direction.” In order to verify whether this concept is applicable to large scooter-type motorcycle, an exploratory study was conducted. First, airbag positioning and supporting structure of the airbag was examined. Then, a prototype airbag system for a large scooter-type motorcycle was produced and tested by utilizing a part of ISO 13232: “Test and analysis procedures for research evaluation of rider crash protective devices fitted to motorcycles.” As a result, it was recognized that an airbag with the same concept as a large touring motorcycle could be also applicable to a large scooter-type motorcycle.