We had proposed the worm gear with new tooth profile for Electric Power Steering (EPS) which could make the worm wheel diameter small. This new tooth profile was derived by solving subject of the fundamental factor which reduced efficiency from a viewpoint of meshing, the strength, and the friction of the worm gear. In this paper, in order to reducing torque fluctuation in a high torque of stationary steering about this new tooth profile, from a view point of load distribution of worm gear, new modification method of this new tooth worm gear was found out. Verifying the effect of this modification, the gear was actually manufactured, and by measuring torque fluctuation of worm gear, the torque fluctuation was verified to reduce in spite of single thread worm gear.

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The drag reduction system which consisted of the rear underbody slant and the rear flat flaps of a bluff-body was optimized by using design of experiments with robustness for cross wind. Drag force measurements accompanied by the orthogonal array were carried out at the low turbulence wind tunnel varying in the yaw angle. As a result of the analysis of variance, it was identified that the rear underbody slant angle, the lower and upper flaps' lengths were significant to the drag force while the side flap's length and interaction effects were insignificant. The slant angle, the most significant factor, should be set very carefully in designing the drag reduction device.

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The unstable operation of the engine is found, when the pressue in the injection pipe of the DME(CH₃OCH₃) engine is lower than the saturation pressure of DME. This fact means that the flow of DME is choked by the bubbles which are generated by the cavitations and the injection rate of DME to the combustion chamber is too small to run the engine smoothly. In order to prevent the unstable operation of the engine, the pressure of DME in the injection pipe is always over its saturation pressure. The flow generated by the rapid moement of the solenoid valve simulates the injection system of DME fueled diesel engine. Experimental results conducted that the instantaneous pressure in the pipe depends on the wave propagation and the vibration of solenoid valve. The measured pressure in the pipe agrees with the calculated value by the one-dimensional unsteady DME flow model.

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We have developed a measuring method that can measure liquid fuel (= wet) quantity in an intake port and a cylinder under transient state. The features of this method use specified single-cylinder research engine with rapid shutdown system of valve train for keeping wet condition at that time and control transient engine speed by using a low-inertia dynamo. In this paper, we clarified the ratio of injected fuel at 1^st cycle from cold start (intake port wet: 64%, cylinder wet: 24%, burned fuel: 12%), and increasing process of these wet quantities cycle by cycle.

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The severe conditions under which intake and exhaust valves of D.I. diesel engines must operate (including exposure to hot combustion gas and engagement in a rapid reciprocating motion) present a variety of obstacles to the successful measurement of instantaneous surface temperature which is necessray in evaluation of direct heat loss from the combustion gas to those valves. In this study, the authors have developed new thin film thermocouples of high heat resistance along with a method of leading signal wires out from the valve surfaces to recording apparatus.

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The original DPNR catalyst has been developed to decrease both PM and NOx emissions on the diesel engine. It will be necessary to focus on PM particle number emissions in the future though the development for the decrease of exhaust weight has been considered before now. In this study, the relation between the pore structure of DPNR catalyst and the PM particle trapping was clarified by evaluating the cordierite DPF of average pore size 20 μm or more. Furthermore, the optimal pore structure to trap the PM particle highly effective was discussed.

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Multi stage boosting combined with variable valve actuation system is assumed as a key technology for simultaneous reduction of exhaust emission and fuel consumption on diesel engine. However its potential was not clear. Therefore performance evaluation of the 3-stage boosting diesel engine which was proposed by the simulation result of 1-dimensional gas dynamics simulation software was conducted in this study by using the total engine simulation system (TESS). Single cylinder engine testing was also conducted to make its effectiveness clear. This project is conducted as a part of comprehensive technological development of innovative, next-generation, low-pollution vehicles program in the New Energy and Industrial Technology Development Organization (NEDO).

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Glycerol free FAME technology with alkylcarbonate and alkali solid catalyst has been developed. Novel BDF made from vegetable oil and dimethylcarbonate consists of ca90% of FAME and ca10% of glycerol derivatives, and meets with the specification of EN14214 except for FAME content. In this system, glycerol is converted into glycerol derivatives which can be used for diesel fuel as FAME mixture. Evaporation tests at 600K under microgravity condition also showed that the mixture had equivalent property to normal FAME made from vegetable oil and MeOH.

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The new piston material has been developed in which the type and amount of the added transition metals and the size of the crystallized intermetallic compounds has been optimized. In order to control the size of the intermetallic compounds, the material is not produced by conventional metal mold casting, but by a carbon mold continuous casting method that enables a fine and uniform structure to be obtained. The optimization of the elements forming the intermetallic compounds and the quantity of these elements added, in addition to the addition of refining elements, to enable dispersion of needle-type intermetallic compounds throughout the alloy, has resulted in the achievement of levels of specific gravity and forgeability similar to those of a conventional forged piston material, while increasing strength at high temperatures by 50%.

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Global warming and decreasing energy supply are serious issues we face today. Automobile industries aim to solve these problems by improving fuel efficiency and reducing CO₂ emission. Therefore, there are strict demands for light-wright, fuel efficient cars. One way to reduce car body weight is by replacing steel with aluminum alloy.
Under such a background, an effective steel-aluminum alloy joining technique is required. However, removal of aluminum alloy surface oxide and the control of interface intermetallic compound are difficult tasks to overcome. Furthermore, galvanic corrosion is also a problem when dissimilar materail joint is applied to automobile outer panels.
To solve these problems, we aimed to reduce the welding process temperature by focusing on low temperature eutectic reaction between aluminum and zinc at 382°C.
As a result, we achieved to remove aluminum alloy surface oxide at low temperature, controlled intermetallic compound formation by heat input reduction, and finally achieved higher tensile strength. In this study, we developed dissimilar materials joining technique using Resistance Spot Weling. In addition to static tensile properties, we have already achieved all the other perofrmance requirements for vehicle application, including fatigue properties, high-speed tensile properties, low-and high-temperature tensile properties and anticorrosion performance.

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Tests were performed to investigate the fectors influencing driving force characteristics on 4WD chassis dynamometers using two types of cars and three laboratories. As a result, the cooling fan condition was found to affect tire temperature, which in turn affected the resultant work at the wheel. In addition, the difference of work done at the wheel between on road and on 4WD chassis dynamometer was examined.

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The purpose of this study is to consider an evaluating method of the direct field of view. The angle of the blind spot is one of the evaluating indexes of the direct field of view. However, it is not enough to evaluate the direct field of view with only the angle of the blind spot; the relative position of other traffic must also be considered.
Therefore, a method was proposed for evaluating the direct field of view around the A pillar for right turns at different-scale intersections. For different scale intersections, it is possible to examine the relative position of other traffic like pedestrians in the direct field of view area by using this method.

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We developed a traction control system for electric vehicle, especially in right-and-left independent drive or all-wheel independent drive. The method is based on slip ratio control that aims to keep actual slip ratio below target value. Experimental results of compact electric vehicle show improvement of starting performance on low μ road surface. And we combined this with accelerated-base traction control for expanding its robustness even in all-wheel independent electric vehicle.

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We have proposed G-Vectoring control that is a method for controlling vehicle longitudinal acceleration in coordination with lateral motion and clarified that the control can improve both vehicle agility and stability by full vehicle computer simulation. In this paper, the dynamic characteristics of G-Vectoring equipped real test vehicle realized by brake by wire technology were introduced. We confirmed that the improvement of vehicle motion in view of both handling and ride quality. The experimental results and analytical examinations were discussed in detail.

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This study examines a lane-keeping-assistance system for motorcycles by using a rider control model. By examining the computer simulation with the rider-in-the-loop system consisting of the motorcycle, the lane-keeping controller and the rider control model, the lane-keeping-assistance system suppresses the lateral displacement of the motorcycle and decreases the rider's steering torque. In addition, the virtual point regulator, which compensates the lateral displacement at the virtual point ahead of the vehicle, corresponds to not only the steering torque disturbance but also the lateral force disturbance by choosing the distance to the virtual point.

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We are developing motorized direct yaw-moment control (DYC) system. Since it is composed of one electric motor and double-row planetary gears between rear wheels, yaw-moment can be generated with high smoothness, with small self aligning torque, and without affecting the speed of the vehicle. In this paper, we show the motorized DYC system has high suitability for a lane-keep assist actuator compared with brake or steering actuators.

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We propose the new vehicle dynamics control of in-wheel electric vehicle based on the tire force usage rate. In the vehicle dynamics control, we have adopted non-linear optimizing controller using the direct yaw-moment control, the tire force usage rate and the tire force. Because it has been that DYC is not compatible with the tire force usage equalization and it is important to consider total tire force Fx and Fy as feedback signals for being compatible DYC with the tire force usage equalization. It was found that our control logic devised in the simulation. In this report, an attempt has been made to clarify whether our control logic is effective as predicted by simulation or not for real vehicle by conducting real electric vehicle test run. Our control logic was also found to be effective enough in the improvement of driving stability compared with the other type of DYC. From the experiment result, it has been found that our control logic is very effective for the independent in-wheel motor electric vehicle. Because the electric vehicle handling has become neutral steering by using our control logic, and consequently, the vehicle could be neutrally steer up to higher speed than without control and the other type of DYC.

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In this paper, the beam element for spot welded thin-walled box section beam considering shearing deformation is proposed. Additional warping produced by the bending torsion is analyzed considering local warping of the spot weld zone, and the effective shear modulus to be introduced into the beam element considering shearing deformation is calculated. By using the proposed element, it was shown that the effect of the shearing deformation of spot welded beams with closed and opened cross section could be expressed within acceptable engineering accuracy, and the twist angle distribution of the spot welded beam with the opening could be analyzed.

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LMS algorithm has been used for an active control. But it can only reduce the first and second firing order in order to reduce booming noise. The authors developed the new method by means of modifying LMS algorithm in order to reduce wide frequency band for comfortable car interior space.
This control method was applied to a vehicle. It was obtained that the seat rail vibration level is reduced in the frequency domain of not only the first firing order but also from 200 to 500Hz.

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Injury criteria for the thigh and leg of a pedestrian dummy were determined by comparing section bending moments due to pedestrian lateral impact between FE human and dummy models. A procedure to calculate section bending moment using longitudinal strain data from multiple strain gages affixed to the femur and tibia sections was established. The procedure was validated by comparing the bending moment from the strain data and that from support forces in quasi-static 3-point bending tests.

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Functional near infrared spectroscopy (fNIRS) was used to measure drivers' brain activity while performing driving tasks on a driving simulator. Increased activation in the dorsolateral prefrontal region was observed when driving on a narrow road and when following a preceding vehicle compared with the level seen for ordinary driving. In addition, a difference in the level of activation attributable to the exercise of attention was seen between the different tasks of driving on a narrow road and ordinary stop-and-go driving.

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In recent years, handle type electric powered wheelchairs become important transportation of persons with disability and elder persons. However, there are few study about behaviors of wheelchair's users in accidents. Therefore, we performed collision experiment of a wheelchair and a passenger car. The experiment revealed that a contact with road surface is a severer injury causation for wheelchair user than a contact with vehicle bonnet.

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A FE model for the lower limb of the modified version of a pedestrian dummy developed by the authors for improved biofidelity have been developed. The moment-deflection characteristics of the femur and tibia and the moment-angle characteristics of the knee joint were validated against dynamic 3-point and 4-point bending experiments, respectively. The results of the model validation were quantitatively assessed using a published procedure used for dummy biofidelity evaluation.

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A multilayer sound absorption/insulator including porous material is difficult to predict performance because of a number of design parameters such as Biot parameters and production tolerance. We developed a performance prediction system based on set-based design method that can obtain a ranged set of design solutions that satisfies sets of performance requirements through set-to-set space mapping from design space to performance space and space narrowing to eliminate infeasible design subspaces. Moreover, our system is applied to sound absorbency and insulation prediction.

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Influences of fatty acid methyl esters (FAME) on the combustion characteristics of diesel engine are examined by the engine performance test and the cold start test. Tests are conducted by using three kinds of FAMEs made from coconuts oil, tallow (beef suet) and soybean. Tests are made at full load and 3000 rpm. Ignitability and combustion characteristics of three kinds of neat FAMEs are compared from indicator diagrams. The coconut-oil methyl ester which mainly consists of saturated fatty acid has superior ignition characteristics on the cold start test, however the break mean effective pressure is lower than other FAMEs.

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4-stage-injection consisted of pilot-, pre-, main-, and after-injection was applied to a single cylinder direct injection heavy duty diesel engine to achieve lower emission under the condition of diffusive combustion. Soot suppression mechanism of 4-stage-injection was investigated using a 3D-CFD calculation. Since separately injected fuel effectively use oxygen unused for the main combustion, pilot- and pre-injection generates no soot and soot from after-injection is oxidized rapidly. Lower soot is formed from less main-injected fuel when 4-stage-injection is applied. These two effects provide reduction of soot emission.

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The purpose of this study is to evaluate effect of fuel ignitability and volatility on spray and combustion characteristic. The fuel is paraffinic that is imitated with Fischer-Tropsch Diesel Fuel (FTD). The spray characteristics of the fuel were investigated taken by shadowgraph photography and Mie-scattered light imaging. The combustion characteristics of the fuel were evaluated taken by direct photography. The two experiments were performed with a constant volume combustion vessel. Two major results were obtained in these experiments. First, the fuel volatility and kinetic viscosity affect liquid phase penetration. Second, the fuel ignitability and volatility affect soot formation.

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Instantaneous surface temperature of the intake and exhaust valves in a DI diesel engine was measured by newly developed thin film thermocouples. Characteristic unsteady behaviors in the surface temperature and the corresponding surface heat flux were clearly captured. Direct heat loss ratio, a percentage of the lost heat to the fuel energy, amounted to approximately 1.5% at the intake valve and 1.0% at the exhaust valve.

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The effects of fuel properties on the characteristics of the PM particle were investigated by using several experimental PM samples. The PM samples were obtained through the thermal cracking reactor by using typical fuels, two commercial Diesel fuels containing aromatics (JIS-2, Class 1) and some paraffin-based Gas-to-liquid (GTL) fuels with different distillation temperatures. In this report, it was found that an aromatic content , carbon number and carbon number distribution of the fuel have a profound effect on the characteristics of the PM by using some analyses such as XRD, thermal and spectroscopic methods.

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A LPG engine has the characteristics of lower NOx emission than the gasoline engine. In this study, in-depth consideration made this mechanism clear that the main cause of this NOx reduction was the decrease in local combustion temperature of LPG by high water content in its combustion products. In addition, increase of EGR was tested in order to reduce NOx emission more and to improve BSEC. As a result, combustion stability of the LPG engine is greater than that of the gasoline engine enough to improve these performances.

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Interaction of fuel spray and surrounding air plays important role to mixture formation, ignition and combustion processes in diesel combustion. Effects of supercharging, swirl strength and fuel injection pressure on development, ignition and combustion process of diesel spray were investigated by using free pisto type rapid compression machine. Detailed observation of the spray was carried out by visualization including schlieren photography and direct photography. The experiments show the results as below. There is an optimum strength in swirl for favorable mixture formation. Higher supercharging pressure makes swirl more effective. Higher injection pressure increases the amount of well-prepared mixture prior to ignition, thus it results less smoke.

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The Local-contact Microwave-heating Injector (LMI) was designed with the coaxial cable. The coaxial cable can make the lines with less restriction of the line layout to transfer the microwave. The coaxial cable also realizes the high spatial microwave density at the end of the coaxial cable, where the microwave irradiates. The microwave generator was controlled with the inverter and the source was AC100V, 60Hz. The fuel temperature near the injection hole was measured with the sheath K-type thermocouple. The fuel was ethanol. The images of the sprays were caught with 130Mpix CCD camera, 1200fps high speed camera. A laser diffraction method was used to evaluate the distributions of the droplet diameter. As the result, the droplet diameter that showed the maximum volume ratio was decreased when the fuel was heated with the microwave.

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One of the main issues for the gasoline HCCI engine system is a realization of SI-HCCI combustion switching. A combustion switching control method was proposed in the previous report, which controls A/F ratio and internal EGR rate strictly. However, the previous report focused on a combustion switch under the steady operation conditions. In this paper, a combustion switching method under the transient operation conditions is investigated. A control algorithm is proposed in the basis of the combustion switching concepts. Its validity is confirmed from the experimental results.

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The cellulosic liquefaction fuel (CLF) is made from woods by the direct liquefaction process. The purpose of this study is to analyze the ignition characteristics and performance of CLF applied to diesel engine. Diesel fuel and CLF are mixed and the blended ratio of CLF is changed. The blended fuel can be burned by diesel engine, when the mixing ratio of CLF is up to 35 [wt%]. The engine performance is almost the same as that of diesel fuel until 20 [wt%] of mixing ratio, however the cold start ignition performance is inferior in comparison with diesel fuel.

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An analyzing system of oil film behavior was developed which measures oil film thickness on the piston skirt bearing area using oil film images obtained by high-speed digital camera through the sapphire liner. Quantified oil film images were animated to observe oil film movement and analyze the factors affecting the oil film formation on the piston skirt. As a result, new phenomena of the oil supply route to the skirt bearing area were observed during the upward stroke of the piston as well as the downward stroke. The factors influenced to the oil film formation were identified.

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Pin noise occurrence due to the impact of the piston pin against the pin boss bearing is one of the typical engine noises emitted from piston related regions. The detailed mechanism of the pin noise is yet to be clearly understood.We have measured contact force and acceleration generated in the circumference of the pin under the condition of engine operation and analyzed the mechanism of this phenomenon in detail.

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In this study, the emission gases of diesel engine were evaluated by changing intake valve close timing (IVS) in a single cylinder DI diesel engine which is installed digital hydraulic variable valve actuation system. Moreover, when the effective compression ratio is made almost equal at compression ratio (ε=14,16,18) by adjusting IVC, the influence of low ε and high ε on the exhaust emission, fuel consumption and operating load of premixed compression ignition combustion was examined. As a result of experiment, it is found that low ε is effective to raise operating load and the operating load of high ε is limited at low level due to the increase of Smoke.

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Quench of turbulent flame kernel and its incidence factors were studied for methane-air flames. Quench of turbulent flame kernel occurred at large turbulence Karlovitz numbers both for lean and rich flames. Lean flames quenched at higher turbulence Karlovitz numbers compared to rich flames because the Markstein number of lean flames were smaller than those of rich flames. Quench of rich flames may be due to the thermo-diffusive effects induced by the flame stretch. On the other hand, quench of lean flames may be due to the incomplete reaction because of their small burning velocities.

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In this study, differences of laminar burning mechanism between LPG (C₃H₈, n-C₄H₁₀, i-C₄H₁₀) and regular gasoline were investigated in detail with one-dimensional premixed laminar flame simulation. Furthermore, the effect of above differences on burning velocity of SI engine combustion was investigated with experiment and two-zone model analysis. In the results, a main elementary reaction which influences a difference of laminar burning velocity was extracted. As for burning velocity of SI engine, the difference derived from that of laminar burning velocity between C₃H₈ and gasoline was significant, and that of C₃H₈ was faster than that of gasoline under low engine speed.

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For the valve train with camshafts and roller followers, influences of the roller support bearing and the engine oil properties on the friction losses at the contact between cam and roller follower and the contacts of other elements in the valve train were examined by measuring the contact load and the friction force between the cam and the roller follower with a practical sized OHV valve train friction tester. The followings were made obvious. (1)The friction loss is smaller with the roller support of slide bearing than that of needle bearing. (2)When the viscosity of low-SAPS engine oils becomes low, the friction between cam and roller hardly changes but that from the other valve train elements slightly increases. (3)The friction loss becomes smaller with the low-SPAS engine oils lower in sulfur content.

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Low sulfated .ash and fuel economy DL-1/C20W-30 diesel engine oil was developed to meet PM regulation in Euro5 and CO2 140g/km. The trilemma of high detergency, low sulfated ash, and fuel economy were achieved in the higher dimension in this development, and 2% fuel economy improvement and 3g/km CO2 reduction were achieved while corresponding to Diesel Particulate Filter.

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The effects of biodiesel oxidation on exhaust emissions in a diesel vehicle were investigated together with chamical components in the fuel. The biodiesel fuel made from 30% Rape-seed Methyl Ester blended fuel(RME30) was oxidized deliberately. When total acid number of the oxidized RME30 is low, there is little polymer and acid formation independent of peroxide number. The exhaust emissions in a diesel vehicle operated on the oxidized RME30 decrease or slightly increase compared to those for the fresh RME30. There is little negative effect of the oxidized biodiesel fuel within a low total acid number level on diesel exhaust emissions.

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It had been revealed that the fatigue life of the hot forging die for a connecting rod was improved by cavitation shotless peening (CSP). In the present paper, in order to improve peening intensity and reveal surface modification by CSP, Vickers hardness, surface roughness and residual stress changing with depth of the specimen made of tool alloy steel peened by CSP were measured. It was revealed that peening intensity was improved compared with SP and former type of CSP, and residual stress in sub-surface was changed with processing time of CSP.

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We have been developing a driver model which reproduces differences of vehicle motion in differnt situations and individuals. In this paper, we assumed key parameters which affect acceleration and steering behavior, such as transient response coefficient and lateral acceleratin, and investigated the variation of those parameters when driver characteristics and driving situation changed. We also investigated the relationship between those driver parameters and the result of a questionnaire survey on driving style. As a result, we confirmed a possibility to predict varied vehicle motions by using individual driving parameters estimated by the questionnaire survey.

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Trends of tracking error, reaction time, heart rate, eye closure, Electroencephalogram (EEG), and sleepiness expression on monotonous task were measured and compared. Sleepiness expression had the strongest correlation with EEG in comparison with the other indexes. Tracking error and reaction time increased after participants were evaluated as falling into doze by sleepiness expression. These results show that sleepiness expression is useful to measure drivers' sleepiness level before falling into a doze. In addition, three types of trends were found on heart rate.

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This paper is concerned with a quantitative classification based on driver characteristics of steering maneuvers. The evaluation indexes that can be used for quantifying differences of driver groups such as experimental driver or beginner driver are proposed. The crank course test using actual car is performed in order to find the evaluation indexes to classify the driver's steering maneuvers. Then the crank course test using driving simulator is performed when gear ratio and a course width are changed. The characteristics of driver's steering maneuvers using these indexes are classified. It is demonstrated in this investigation that the method can be effectively used for classify an important characteristics of driver's steering maneuvers.

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This study investigates effects of hierarchization of auditory signal on driver behavior when various information provision services are introduced into in-vehicle information systems. The characteristic of auditory signal was determined based on subjective criticality and urgency for each information services. Moreover, motion-based driving simulator experiment was conducted, and driver behaviors were measured and evaluated comparing between the information services with hierarchized/non-hierarchized auditory signals and voice messages. The results show the information service with hierarchized auditory signals is more effective for collision avoidance than that with non-hierarchized auditory signals. Voice messages may confound drivers in recognizing criticality of information service, although the information service with voice message is slightly more effective than that with hierarchized auditory signals.

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A driver-distraction is an improtant traffic safety issue to avoid the degradation of driving performance. VOR (vestibulo-ocular reflex), and involuntary eye movement is used in this paper to evaluate the driver-distraction. VOR was severely affected in our previous studies according to task workloads presented on the central vision. This study extends the scope of the previous ones to consider the relationship between VOR and task workload on the peripheral vision. The experimental results suggests that processing resources for task workloads in the central vision and peripheral vision are separated, and 'n-back' task which involves highly complex informatin processing rarely affected VOR.

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This paper proposes the preview speed control for suppression of the shockwave propagation to prevent traffic congestion with communication systems which transmit the speed or the acceleration information from the downstream vehicle or infrastructure to upstream vehicles. The simulation studies indicate the improvement of the traffic flow by the proposed system even under a condition of a low penetration rate of the communication systems.

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The methodology for evaluating the effectiveness of information presentation regarding oncoming vehicles at intersection in terms of the reduction of traffic accidents was proposed. At first, driver's behavior such as the relation between the distance to an oncoming vehicle and the frequency of right-turning at intersection was analyzed, when the field of view was changed and the information system presenting the distance to an oncoming vehicle was used or not, in a driving simulator with 50 participants. After that, the driver's operation model simulating the right turning at the intersection based on the driver's behavior analyzed in the experiment was coustructed. The frequency of collision at the intersection was analyzed through 10,000 times of simulations at each condition by making use of this driver's operation model. One of the results show that the frequency of the collisin was decreased from 6.1×10^-3 to 1.0×10^-6 in condition that the field of view is extremely short such as 40m at the intersection when the driver used the information system for avoiding the collision.

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