This research investigated the influence of thermal conductivity of piston on cooling loss and exhaust loss in a spark ignition engine. In the experiments, operations with a conventional piston made of aluminum alloy and a low thermal conductivity piston made of magnesium alloy were compared in an engine fueled with ethanol and hydrogen. Experimental results show that the low thermal conductivity piston brings higher thermal efficiency and larger exhaust heat by reduced cooling loss.

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Low emission and high efficiency is required of diesel engine. Therefore, it is necessary to develop a technique instead of high injection pressure, because efficiency of atomization is very low in this method. Our study suggests EGR gas dissolved fuel which improves spray atomization by effervescent atomization. In this paper, the purpose is to evaluate the influence of the combustion characteristics of the CO₂ dissolved fuel. As a result, the higher dissolved pressure has the lower flame temperature and flame KL factor. Therefore, the simultaneous reduction of NO_x and soot can be achieved by use of the CO₂ dissolved fuel.

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We have proposed the application of EGR gas dissolved fuel which might improve spray atomization through effervescent atomization instead of high injection pressure. In this paper, the purpose is to evaluate the influence of the application of CO₂ gas dissolved fuel on the combustion characteristics and emissions inside the single cylinder direct injection diesel engine. As a result, by use of the fuel, smoke is reduced by about 50 to 70 %. The amount of NO_x is reduced at IMEP_g (Gross Indicated Mean Effective Pressure) = 0.3 MPa, but the amount of it is increased at IMEP_g = 0.9 MPa.

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For the improvement of the transient driving performance of a diesel engine, it is useful to control the fuel injection timing and quantity using model-based control (MBC). The authors previously developed the on-board in-cylinder gas flow model and the wall heat transfer prediction model, which are a part of the models for MBC. However, the developed gas flow model contains an undecided constant called as turbulence intensity coefficient (TIC), which has the significant effect on the wall heat transfer prediction model. The present study evaluated the TIC by using the in-cylinder gas flow velocities obtained from the PIV measurements, which were measured at multiple planes and were analyzed by separating the velocity to mainstream and turbulent components. Furthermore, we compared between the heat fluxes from the experiments and those from the model with the TIC, and it was found that the model with the coefficients obtained by using velocities at the lower part of cylinder was agreed with the experiments, because the error ratio was evaluated to be -4.7%. Finally, for the identification of the TIC without any experiment, we calculated the TIC using velocities at the lower part of cylinder obtained by CFD analysis. It was obvious that the heat fluxes from the model with the TIC was agreed with the experiments, because the error ratio was evaluated to be -3.8%.

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In this study, combination of PCC (Plume Ignition and Combustion Concept) combustion, in which plume of fairly rich air-fuel mixture is ignited and burned immediately after completion of injection in the latter half of the compression stroke of the in-cylinder direct injection hydrogen engine proposed by the authors so far, with optimized hydrogen jet configuration such as the direction of the jet flow, diameter of nozzle hole and injection timing and combustion in the lean air-fuel mixture region markedly improved thermal efficiency and reduced NOx emissions at the same time. As a result, hydrogen engine which does not emit any CO2 and particulate matter emissions in principle is worth to be called near-zero emission hydrogen engines in both name and reality.

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In dual fuel compression ignition engines fueled with diesel and gaseous fuel, an increase in unburnt gaseous fuel emission and thermal efficiency deterioration caused by high unburnt emission under low load are main drawbacks. In this study, combustion chamber design is optimized to reduce the unburnt gaseous fuel emission by using a genetic algorithm in conjunction with the KIVA-4 computational fluid dynamics combustion simulation code. The simulation results show that the optimized chamber design improves the unburnt gaseous fuel emission and thermal efficiency.

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Multiple injection often come to use for post injection, and the injection quantity per injection is small-quantity. Therefore, it is thought that Spray characteristics in post injection are different from that in main injection. This is important to comprehend the characteristics of small-quantity spray such as post injection. This report, the characteristics of small-quantity spray was obtained from various spray measurement. As a result, small-quantity spray was greatly affected by sheet throttle due to low needle lift movement. Therefore, Sack pressure (P_sac) tended to be equal regardless of the Rail pressure (P_rail). Also, it is influenced by acceleration of atomization due to an increase in Sac pressure under the injection quantity assumed to be used in post injection. For this reason, it was found that there is a region in which the spray tip penetration is suppressed.

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During forced regeneration of a diesel particulate filter, it is important to set an optimal regeneration timing and duration in consideration of pressure loss and fuel efficiency. Generally, the relationship between regeneration period and pressure drop are predicted by numerical calculation, but depending on the conditions, the prediction accuracy during regeneration may not be sufficient. In this study, we proposed a reaction equation based on the Arrhenius equation and shrinking sphere model to improve the prediction accuracy. Finally, the relationship between regeneration temperature and time was revealed by the proposed model.

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Fuel injection control is effective to improve the thermal efficiency of a diesel engine. In order to predict the gas temperature at the start time of fuel injection, the authors have previously developed an on-board polytropic index prediction model for the compression stroke with low calculation load based on physical principles. However, to estimate the indicated mean effective pressure (IMEP) required in its model, the diagram factor has been assumed to be a constant. In this study, a regression equation for diagram factor was derived based on numerical simulation results. Since the diagram factor depends on the centroid of heat release rate (CA₅₀), a regression equation to estimate the CA₅₀ based on operational conditions was determined. The average error between the IMEP estimated using the regression equations and experimental results was 1.2%, and the usefulness of the regression equation was confirmed.

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In the conventional map control, the number of calibration becomes large to make the map for transient driving conditions, which leads to extend the development period and increase the development cost. To overcome these shortcomings, the development of the model-based control is required. The previous model-based feedforward (FF) controller for diesel engines used several empirical equations based on experiments to predict the polytropic index for the compression stroke considering heat losses. To reduce the number of experiments, the authors developed the physical model for predicting the polytropic index (referred to as the present model) and implemented on the above FF controller. Under the transient driving conditions, it was found that the FF controller with the present model could predict the polytropic index with an average error of 0.31% and the indicated mean effective pressure (IMEP) with the maximum difference of 6.4 kPa, which shows that the present model can be used in place of the empirical equation.

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The effect of pilot injection conditions on cold startability of a diesel engine under low-temperature condition was evaluated experimentally. Test engine was installed in a low temperature test room where the temperature was set at －25℃. Injection strategy during cranking period was two-stage injection consisting of a pilot and a main. By measuring dynamic strain of a glow plug using a strain gauge, measurement of cylinder pressure was carried out. Rate of heat release was derived from the cylinder pressure, and ignition quality of the main injection was evaluated from a profile of the rate of heat release. The profile of the rate of heat release indicated that the ignition quality of the main injection was affected by the pilot injection timing and the appropriate timing of the pilot injection was varied by the engine speed.

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The vaporization efficiency of injected urea aqueous solution into Urea SCR systems is improved by promoting atomization at wall colliding. This paper suggested the promotion method of an atomization by several texturing ideas on test materials. The wall colliding behavior of water droplets was visualized by backlight method. The particulate size and speed were measured from the visualization results using software. The texture shape of the higher atomization promotion effect was decided by comparing Weber number which was calculated. Furthermore, the atomization promotion mechanism by adding the surface texture was predicted from the visualization result in high-magnification.

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In this study, judgement criteria for corrosion of piston pin bushing has been developed, which enables evaluation of design validity against corrosion before running engine durability test. Judgement criteria were obtained by performing plenty of tests by test rig simulating actual environment of bushing in engine with acceleration test conditions. The judgement criteria enable to predict corrosion state by estimating contact pressure and temperature of bushing at design stage.

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A pinion gear using an involute tooth profile can be characterized as having high transmission efficiency. However, if the number of teeth is reduced to one for high speed reduction, the operating pressure angle becomes large and the transmission efficiency becomes very low, so it is said that practical use is difficult. In this paper as the number of teeth is reduced to one, the transmission efficiency is successfully maintained by making the tooth profile circular and optimizing the operating pressure angle.

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This paper describes a discretization method for the arc spring in the torsional damper with physical modeling approach, and suggests to develop a practical plant model for the arc spring with non-linear characteristic in amplitude and speed dependencies. Non-linear characteristics of arc spring are studied from the torsional damping performance measurements with the low inertia dynamometer bench tester simulated the vehicle driveline. Both proposed method and conventional model are validated by experimental results in different rotational speed and different excitation amplitudes. The efficiency of model accuracy and computation time of both proposed model and conventional model are investigated.

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A damper mechanism was developed that provides high damping performance across a broad range of use by applying a preload force on the dynamic damper spring. The dynamic damper spring is located radially between the primary damper, which is positioned on the outside diameter, and the secondary spring positioned on the inside diameter. The damper mechanism was developed with preload and clearance settings configured for ease of assembly. The dimensions and increase in number of parts were also held down while realizing high damping performance and low inertia mass.

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Heavy-duty electric vehicles (EVs) are expected to increase in the future. At present, power consumption of EVs is evaluated by using HILS (Hardware in the loop simulation), which is calculated by motor/generator model and battery model. Battery model is dealt with on the steady condition (25℃). However, batteries are degraded with age and the performance is affected by a rise in temperature at driving EVs. Therefore, it is difficult to construct a model of batteries. In this study, EVs were evaluated by using a new method which is called Battery-HILS (Battery in the loop simulation). Battery-HILS is composed of an actual battery and HILS, and runs in real time.

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Electric vehicles (EVs) are an important means to solve energy and environment problems. However, their deployment has been hampered by their high cost, their short cruising range and the lack of charging facilities, as well as their long charging time. Those problems are expected to be rapidly solved by the fast and steady technical progresses worldwide and, the massive adoption of EVs is expected to start from around 2025. As an example, in order to reduce the EVs charging time to less than 6 minutes, a 350kW super-rapid charger was developed and a large current charging battery is currently under development. The main concern of charging a battery with 350kW within 6 minutes is that the battery cells may exceed the maximum allowed temperature of 60℃. Therefore, we investigated cooling methods and found out that the most effective one is to use Phase Change Materials (PCMs) to absorb the heat generated by the cells. In this paper, we confirm using simulations that the PCM cooling technology can keep the battery cells below 60℃. We also investigated the issue of heat radiation for PCM.

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Electric vehicles (EV) can be used as not only transportation equipment but also energy storage and leveling of renewable energy generated fluctuations by using EV batteries. In this paper, an advanced V2H(Vehicle to Home) system which is combined with photovoltaic power generator (PV), EV and heat pump (HP) water heater has been studied in order to use renewable energy effectively. In this system, PV power is charged directly to EV battery and surplus electricity that is not used for driving the car is supplied from EV battery to the home. As a result, the advanced V2H system is able to reduce CO₂ emissions by 80% in comparison with the conventional system. And, it is clarified that the V2H system can utilize PV power more efficiently than the mega-solar system in which EV is charged from power system. Additionally, EV battery can be used in the same way as the stationary battery to adjust PV power and the electricity demand.

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This paper proposes a slip detection method for inverters of EV (Electric Vehicle), which drives a vehicle by one traction motor with a differencial gear and driveshafts. It is observed that the resonance frequency of the motor speed changes when tire slip happens. Based on this phenomenon, a slip detection method is developed based on abstraction of a cetrain frequency of motor speed using band-pass filter (BPF) and discrete fourier transform (DFT). According to vehicle dynamics simulation, the proposed method can avoid misdetection of slip when tire is gripping and resonance of motor speed occurs. In addition, the method is affected by transitional response of BPF and DFT, which may delay slip detection.

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This paper presents a design method for continuous fiber composites in three-dimensional space with locally varying orientation distribution, as well as their fabrication method. The design method is formulated based on topology optimization by augmented tensor field design variables. The fabrication method is based on Tailored Fiber Placement technology, whereby the preform is prepared by a CNC embroidery machine. The fiber path is generated from an optimized orientation distribution field. The preform is formed with vacuum-assisted resin transfer molding. The fabricated prototype weighs 120 g, a 70% weight reduction, achieving 3.5× mass-specific stiffness improvement.

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This paper investigates an evaluation method of the sound quality of structure-borne combustion noise on a powertraindynamometer test bench. The analytic procedure is as follows. First, the vibro-acceleration of each engine mount and the cylinder pressure of each cylinder are measured simultaneously. Following this, combustion-related contributions are extracted from measured mount acceleration results using the time domain combustion-related contribution separation method. Next, these acceleration signals are converted to sound signals equivalent to structure-borne noise in the vehicle interior by a finite impulse response filter; this filter simulates the standard vehicle transfer characteristic. Finally, the sound quality of these structure-borne combustion noises is quantified using the existing sound quality evaluation index, the dissonant combustion noise index. This new method was applied to an actual advanced engine development. The results demonstrated the effectiveness of the new method, which makes it possible to examine countermeasures for enhancing the sound quality of combustion noise at early stages of engine development before the completion of a prototype vehicle.

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Almost all the problems of a serpentine belt drive system such as maximum tension, belt slip on the pulley, squeal noise and self-exciting string vibration of the belt are caused by a resonant phenomenon of the belt drive system. In this report, the following items are described on the resonant phenomenon. (1) Eigenvalue analysis that is the method to get the natural frequency, resonant speed and vibration mode of the belt system. (2) Tension mode that can estimate the span of self-exciting belt vibration occurrence, and slip mode that can estimate the pulley of squeal noise occurrence. (3) Some application examples of eigenvalue analysis and methods to avoid or reduce the resonant phenomena.

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When the driver fails to respond to a request to intervene issued by a level 3 automated vehicle, the system considers a way to reduce the risk by performing a system operation called minimum risk maneuver (MRM). In this paper, a driving simulator experiment investigates the effects of MRM condition such as hazard lamp activation, amount of deceleration, and stop position on the following vehicles. As a result of the experiments, one condition demonstrated that the blinking of the hazard lamp in the MRM was effective in reducing the braking response time of the following driver and the maximum deceleration. As a result of arranging MRM conditions to be effective for risk reduction, it was suggested that MRM consistent with the driver’s prediction would be effective.

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The method that the trajectory parts correspond to lane change for safety assessment is rationally extracted, was built, utilizing all the vehicle trajectory data actually generated by image sensing for the heavy traffic sections on urban expressways. Furthermore, we extracted the scenarios with high risk of collision, which are included in the data, and organized their occurrence tendency through evaluation with TTC.

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In recent years, the number of traffic accidents caused by elderly drivers have been increasing. In order to develop driver assistance system, it is necessary to analysis driver’s driving behavior to extract unsafe driving behavior. In this paper, we propose a method that estimate face pose and leaning forward posture by using on-board camera image. We discuss the safety of driving behavior of expert drivers using leaning forward posture.

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The methods that solve the flow equations and the acoustics equations separately are often applied to the aeroacoustics simulations. Although the acoustics simulations are generally applied to the far fields, this paper concerns about the near fields to predict the wind noise observed on the surfaces of automobiles. The acoustic fields obtained by the non-linear, linear, and Lighthill analogy models are compared around a two dimensional cylinder. Furthermore, the acoustic fields around the side window of an automobile are calculated. This paper shows the characteristics of each model with the detailed analysis of the wave profiles.

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In order to enhance the cooling performance and aerodynamics of a vehicle, a front-end cooling structure is improved with Computational Fluid Dynamics(CFD) and optimization algorithm. Multi-objective optimization was implemented and optimal solutions that enhanced both the cooling performance and aerodynamics were obtained. For example, one selected design from optimal solutions shows that the airflow velocity passing through the heat exchanger increased by 14% compared with the baseline while maintaining its aerodynamic performance. To verify optimization results, the vehicle test was carried out with the prototype front bumper based on the selected design in the optimal solutions. The results show that the shape-optimized bumper is effective to improve the cooling and aerodynamic performance.

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The purpose of this study is to construct a prediction method for cavitation erosion in a trochoid oil pump and to examine countermeasures. This paper describes the possibility of erosion prediction using CFD by comparing the CFD analysis results and the experimental results of the cavitation behavior and erosion by the difference in the pump rotational speed. The cavitation behavior results are fairly consistent with the results of the high-speed camera image. There was correlation between the collapse energy computed by CFD using the Gray Level Method (GLM) and the actually measured erosion amount.

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The objective of this research is to construct the particulate matter (PM) emission measurement method with lower measurement variability based on filter gravimetric for PM emission vehicle of less than 1mg/mile. The measurement variability was defined as the standard deviation 1ó, and target level of 1ó was less than 1/20 of averaged PM emission. At first, the PM measurement variability of the conventional testing method based on the current regulation was examined using by direct injection gasoline engine vehicle. A 3-bag Worldwide harmonized light duty test cycle (WLTC) with hot start condition was selected to achieve lower PM emission source from the test vehicle. In addition, the impacts of dilution tunnel heating, filter media and filter face velocity (FFV) for PM collection process on PM emission variability were analyzed base on design of experiments. It was found that the recommendation testing method with Teflo filter and higher FFV setting achieved lower PM emission variability than conventional testing method based on current regulation.

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In Europe, particle number (PN) regulation has been introduced for solid particles larger than 23 nm. For the purpose of future regulation, reducing of target particles is being considered. In this study, we aimed to understand the influence of the difference in CPC lower detection limit on the measurement. Simultaneous measurement of PN emission was investigated with five CPCs settled at exit of Volatile Particle Remover of Particle Number Counting System suitable for sub 23nm measurement. PN emission tended to increase as the lower detection limit of CPC reduced. Contribution of particles above than 23nm was about 80%, and those above 10nm was about 99% in WLTC-Cold test cycle for type approval. Therefore, almost all particles could be measured with 10nm CPC, since the contribution of sub 10nm particles was very small.

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A finite element analysis (FEA) model for predicting the weld fracture is developed using the local plastic strain together with the stress triaxiality σ_m/σ(σ_m: hydrostatic stress, σ: equivalent stress) as fracture criterion. In this study, this FEA model is applied to tension tests of arc welded joints, and is examined the influence of welding wires on joint strength and fracture locations. FEA results show good agreement with experimental results of joint strengths and fracture locations. This method enables clarification of the arc weld fracture phenomenon and the accurate fracture prediction.

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The purpose of this work is to improve cabin VOC and odor quality and meet China market needs. Polyurethane Foam(PUF) materials is one of the main source of cabin VOC and odor. We identified PUF odor compounds as 1) amino compounds from catalyst and 2) aldehydes. Ally ether contained in polyol as impurities convert to aldehydes by acid hydrolysis and they convert to odor compounds 2) by aldol condensation. By 1) using reactive type amino catalyst and 2) reducing impurities of polyol, we developed low VOC and smell PUF and improved cabin air quality.

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This paper describes the development of a simplified modeling method to represent fracture of Self-Piercing Riveted (SPR) joints to be used for aluminum die casting. A fracture determination area of the simplified SPR model was modeled by subdivided solid elements. Fracture criteria were determined based on the peel and lap shear tensile tests. The calculated fracture mode and force-stroke history of a structure composed of aluminum die casting and steel sheet parts showed a good correlation with the experimental result.

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Fracture by tensile loading could be made cause in heat affected zone around the spot weld point. On prebious report, a flange shape that achieved both the performance of the member and suppression of the fracture was found by 4 point bending test simulation. On this report, the flange shape which reduces the tensile stress was considered by 4 point bending test. Therefore, as aresult of experimentally verifying the effect of the flange shape by 4 point bending test, it was confirmed that the member was as expected in the previous report.

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The ring deposits generated on the window glass of cars, buses, trains, were investigated by a chemical approach. The experiments were conducted to generate ring deposits using three types of water containing different silicon concentration. The Si concentration of groundwater was the highest, and the amount of ring deposits was also the higher than that of tap water and rain water. It was clear that the main element of the ring deposit was silicon. It was estimated that the ring deposit was occurred by reaction of the fine particle formation in the water droplet and the chemical reaction between the glass surface and the fine particles. Thermodynamic equilibrium calculation revealed that the main compound in the ring deposit is orthosilicate (H₄SiO₄).

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At wiper system, the self-excited vibration is often occurred, and it is caused some problem, such as a noise, low visibility, and so on. In order to reduce the vibration by control technology, we estimate behavior of tip of wiper arm using extended Kalman filter. One of nonlinear factor is friction between wiper rubber and windshield at wiper system, and the model of wiper system has discontinuity in the velocity equal to 0. Therefore, the Jacobian is so big and it cannot use for the real system. So in this paper, we propose method of applying extended Kalman filter to discontinuity system, without changing structure of model.

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We studied a self-localization technology of vehicle using the developed MEMS mirror type LiDAR. In data processing, we perform the movement correction within a LiDAR frame and the integration of multiple LiDARs. In NDT scan matching calculation, we perform ND map creation and LiDAR data down sampling using reflection intensity information. Results of experiments on general roads showed accuracy within 15cm in the direction of longitudinal, lateral and altitudinal. As a result, we confirmed that highly accurate self-localization can be realized by using above technologies.

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