Due to high dilution and /or high supercharging of a spark ignition engine, the ignition environment is getting severe. Thereby, it is an important key technology to develop next-generation’s spark ignition system by clarifying discharge channel behavior during flow and initial flame kernel growth process. In this paper, the authors investigated the discharge and the ignitability of the mixture in diluted flow field using a constant volume combustion chamber. As a result, the ignitability was found to depend on discharge current, discharge energy and /or ambient gas velocity. Also, the extension of discharge channel by ambient gas flow was found to shorten the discharge duration and also to increase the discharge energy, leading to good ignitability.

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In the conventional map control, the number of adaptations 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 modelbased 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. For the verification of the sensitivity of the polytropic index to the control results, we compared between the FF controller with the empirical equation and that with the present model. Under the steady driving conditions, it was found that the FF controller with the present model could predict the polytropic index with an average error of 0.22% and the IMEP with the difference of 8.56 kPa, which shows that the present model can be used in place of the empirical equation.

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In this study, we constructed a soot formation model which describes the process of PAH growth up to about 60 carbons in three sections and can predict soot formation by combining with the method of moments. This model was combined with the gas phase reaction model of Miyoshi et al. which is a model for gasoline surrogate fuel including the growth process up to benzene and toluene. As a result of model adjustments and verifications using the experimental results for a gasoline surrogate fuel measured by shock tube, it was found that the basic bell characteristics can be reproduced well when arranged using the ambient temperature, regardless of the pressure and the amount of oxygen.

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Soot and ash transport behavior has been investigated using a diesel particulate generator (DPG). It was revealed that ash accumulation pattern strongly depends on the soot amount accumulated in the DPF at the onset of regeneration by analysis using X-ray CT imaging. From in-situ visualization using an optically-accessible full-sized DPF, soot transport behavior was observed frequently when the accumulated soot amount became larger. The plug ash is formed by the soot transport involving the ash particles, while the wall ash is formed when the accumulated soot amount is small. In addition, the ash accumulation structure, such as packing density and permeability, was examined in detail.

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In the former report (3rd report), authors applied temperature swing insulation pistons except piston cavity, which is to avoid deterioration of the specific fuel consumption due to the surface roughness. In this report, the performance of heat insulation by temperature swing was investigated with the different surface roughness pistons. As the result, the better surface finishing showed the lower specific fuel consumption. Furthermore, utilizing the increased in-cylinder gas temperature of pilot combustion with insulation, fuel injection strategy was re-calibrated, and showed further specific fuel consumption improvement.

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Low emission and high efficiency is required of diesel engine. As a method of improvement of the combustion, high pressure injection is carried out. But, efficiency of atomization is very low in this method. Therefore, it is necessary to develop a technique to atomize and distribute spray under low injection pressure. Our study suggests EGR gas dissolved fuel. EGR gas dissolved fuel improves spray atomization by effervescent atomization. Furthermore, NO_x emissions are reduced by Internal-EGR gas. As basic research, the purpose of this paper is to evaluate the influence of the combustion characteristics of the CO₂ dissolved fuel spray.

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This paper clarifies the relationship between basic technology area and basic vehicle performance obtained from university-industry collaborative research in the power transmission system technology area where companies in multiple layers cooperate. Specifically, the process in basic technology area of air bubble control technology for oil bubbles is visualized to improve the shift characteristics of CVT for vehicles. By describing the methodology for returning the results in the basic technology area to the participating companies, we discuss effective methods for sharing the results of collaborative research between the principle side and the application side in each process.

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Toward the widespread use of polymer electrolyte fuel cells to the electric vehicles, the degradation of carbon support at the cathode should be resolved. The cell performance using high durable Pt/Nb-SnO₂ cathode catalyst layer was higher than that using Pt/GCB by decreasing ionomer content. The increase of primary pore volume in Pt/Nb-SnO₂ catalyst layers mitigated the overpotential originated from the gas diffusion. The increase of secondary pore volume in the catalyst layers also prevented the water flooding.

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This paper considered the root loci plot when the velocity was changed by using 3 degree of freedom (D.O.F) model consisting of plane 2 D.O.F motion and roll 1 D.O.F motion. As a result of the parameter study, this paper pointed out that the two root loci may become double roots in a case. On the lower speed side than the vehicle speed at which the double root occurs, the yaw natural frequency was about 30% larger than that of the 2.D.O.F plane model. Thus, an approximate expression of the yaw natural frequency in this vehicle speed range was proposed.

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In the sensory evaluation of the driver, the steering transient response is divided into stages, and the phenomena of each stage is explained. In order to improve the steering response based on the understanding of this explanation, the stage of the steering transient response was theoretically categorized. Further, I pointed out the order in which response indices become apparent for each stage. As a result, it turns out that it becomes manifested in order of fast response, yaw lead time constant and yaw natural frequency.

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The reason of oscillating motion in steering of an automated driving bus at middle speed range is revealed and feedback control with six variables, including front tire angle, is proposed to damp the oscillation. Real-time kinematic GNSS with centimeter accuracy is used for selflocalization and the angle of the steering wheel is controlled by a motor equipped on the steering shaft. Root locus method considering the relation between lateral error and feedback gains indicates damping of the motion of the vehicle become smaller at middle speed range than at low speed range. The numerical simulation and experimental results show the six state variables feedback control has an advantage in obtaining high damping ratio with avoiding the vehicle leaving the travelling lane under the influence of the lateral wind and the transverse gradient.

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This paper investigates real-time optimal control for an autonomous vehicle. The clock-based real-time optimal control that generates the so-called Carathéodory-π trajectories has found wide applications in recent years due to an increase in computational performance. The applicability of a propagation type Carathéodory-π control algorithm for the vehicle in the curved road is investigated by numerical simulations using the full-vehicle model. Results demonstrate that the sequentially calculating optimal control command given by a simple dynamical model has the potential for the real-time optimal control of the conventional type vehicle.

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To enhance the accuracy of the conventional correction of tire rolling resistance, viscoelastic characteristics was taken into account in method. Specifically, a tire rolling test bench capable of controllable ambient temperature was used to determine the relationship between tire rolling resistance and temperature fluctuation. To use of the correction formula derived from that relationship has made it possible to apply highly accurate correction. This correction formula is effective in terms of enhancing the accuracy of running resistance. On the other hand, this method had issue that rolling resistance bench of controllable ambient temperature had to be used. In order to resolve this issue, the use of temperature characteristics of tire rolling resistance extracted from separate measurement results was verified. The results showed that both methods yield values that are close to the actual measurement values within an error of ±1%.

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Market specific driver behaviors as well as demands and the vehicle manufacturers’ efforts to achieve brand specific drivability characteristics as unique selling propositions, require an objectified evaluation and classification approach for vehicles drivability capabilities. This objectified approach enables frontloading of drivability related engineering tasks and even allows to start drivability calibration tasks already in early component conception phases of a new vehicle or a vehicle derivate development program. Furthermore, this approach can be adapted to various closed-loop co-simulation testing scenarios (e.g. Hardware-in-the-Loop or Engine-in-the-Loop). This article presents the capabilities of an objectified drivability evaluation and classification approach, which is based on physical criteria, for passenger vehicle development programs.

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Steering behavior is affected by driving tasks and vehicle characteristics. In this study, driving behaviors during lane change tasks were first quantified through measurement and identification. Three handling parameters in the driver model were identified using logged experimental data of driver steering angles and vehicle trajectories. Second, the relations between distance of lane change section and the identified parameters were statistically analyzed. Third, the effects of vehicle motion-response characteristics on the identified parameters were also statistically analyzed. Consequently, the lane change section was found to mainly affect two of the identified parameters, while vehicle motion-response characteristics determined the other parameter.

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It is known that the lateral force shows transient characteristics when the wheel axle is vertically oscillated with some frequencies. The purpose of this study is to clarify the mechanism of transient tire lateral force under time-varying vertical load. At first, the lateral force responses were measured under the wheel axle oscillated and at a constant small slip angle of one degree with a tire rolling speed of 60km/h. We obtained the result that the lateral force decreases depending on the oscillated frequency of the vertical load. Next, the tire model based on tire brush model was developed for calculation of transient lateral force. The calculated results showed good agreement with trend of experimental results. As a results, It was found that the apparent slip angle fluctuation had an effect on the transient lateral force.

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As electrified vehicles become more widespread, the primary approach to braking is shifting from wheel brakes to regenerative brakes. Under these circumstances, this paper proposes a new brake system architecture called the triple hybrid brake system (THBS). THBS features a new high load brake installed on the vehicle body, and restricts the role of wheel brakes to low loads. As a result, THBS helps to reduce the unsprung mass. First, the basic design guidelines were obtained using a 2-DOF vibration model. Then the effect was confirmed by driving simulations of a 3-D vehicle dynamics model.

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The triple hybrid brake system (THBS) proposed in the previous report is configured with three braking elements: a wheel brake, regenerative brake, and high load brake. Therefore, it is important that the braking force distribution and cooperative control system considers the properties of each braking element. This paper describes a basic brake simulation based on a single-wheel vehicle model. The brake control factors adopted by this model are a time constant, gain, and dead time. These parameters were used to devise, an appropriate braking torque distribution algorithm, which was then verified in a deceleration simulation.

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The automotive industry continues to develop new power plant technologies such as downsizing, rapid combustion for fuel efficiency. But engine excitation force will be increased by those, it’s very important to improve the isolation of engine mount. This paper proposes new active torque rod by using Axiomatic Design which can be simple design methodology against conflicting requirements. Our technology principle consist of big improvement of the isolation level by lowering the resonance of torque rod and applying the damping force by inertial mass actuator. We successfully achieved good NVH level on L4 downsizing engine as same as V6 engine.

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Engine noise is considered to decrease by electrification of the vehicle drive power. In this study, we evaluated the drivers’ vehicle-speed control abilities by the perception of the engine noise so as to investigate influence of the engine noise on their vehicle operation. As the result, the speed control ability was decreased significantly by the reduction of the engine-noise especially in accelerating and cruising conditions. On the other hand, the ability was increased by adding a high order pure-tone noise component in the reduced engine-noise reduction condition.

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A semi-active suspension has been widely adopted to enhance vehicle performance. In order to improve occupant ride comfort and tire road holding using a semi-active suspension system, a variety of suspension control methods have also been proposed for a long time. In this paper, we configured the triple skyhook control, which features reducing sprung vibration over a wide frequency range with a simple control law, for a test vehicle equipped with a semi-active suspension system to enhance ride comfort. We confirmed that the control showed high performance to the sprung vibration suppression over a wide frequency range and its results were verified on a test vehicle.

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Previously the authors developed the dissonant combustion noise index (DCNI), which is an objective evaluation index for combustion noise quality in vehicle interiors. At present, the DCNI is used effectively in actual mass-production vehicle developments. However, the DCNI was developed based on the results of subjective evaluation experiments conducted by 14 experts in engine vibration and noise, hence it is pointed out that its effectiveness for the feeling of general vehicle users has not been verified. Therefore, subjective evaluation experiments of combustion noise were conducted based on Scheffe's paired comparison method. A total of 19 experts and 200 non-experts (general vehicle users) evaluated 15 different combustion noise in three different speed conditions using a headphone playback system. The results demonstrated that the DCNI is appropriate as an objective evaluation index to enhance engine sound quality in vehicle interiors.

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This study aims to develop a shared control based steering assistance system together with a defensive brake control in order to achieve safety margin form a potential risk ,and operate a steering with stable manner in same driving maneuver with an expert driver. The key feature of the proposed system is to indicate a reference steering angle with the haptic steering control torque by using the key concept of the shared ratio (SR) in the condition of risk predictive brake control. To investigate the effectiveness of the proposed system, the experiment in a parked vehicle overtaking scenario was conducted by using the test vehicle. Thirty-two elderly drivers were employed, and the changes of the maneuver characteristics were evaluated. From the evaluations, the positive shared control characteristics are confirmed in the condition of with SR=0.5 (soft) control.

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For maintaining and improving the drivers’ condition in a highly automated driving support system, we are examining a new interface to promote their voluntary behavior for keeping own arousal state. The interface is composed of a neck pad attached to the driver’s seat, and the neck pad has a cooling system. We report the evaluation of the effects for keeping their arousal state at 2 temperature conditions of the neck pad’s surface with 10 subjects in laboratory experiments.

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Although an industrial vehicle has several operation buttons, there are few regulations/guidelines for these layouts. Because of this, there are often gaps between the user-expected layout and the actual layout. Therefore, it is very important to minimize this gap. However, it is difficult to accurately design a user-expected layout because currently there are no effective methods to measure this gap. In this study, we propose a method for evaluating the gap between the user-expected human machine interface layout and the actual layout using the P300 component of event-related potentials, by using a passenger vehicle as the initial step.

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This work provides an effective numerical approach to predict thermofluidics in a tu rbocharger. In the standard CFD approach, a huge number of meshes are required to represent a complicated blade shape in the turbine or the compressor. In order to reduce the calculation cost, the present work proposes a momentum source model, in which the effect of the blade-rotation is taken into account through the source terms representing the momentum-generation by the blade-rotation without considering the actual shape of the blade. In the original model,1) the obtained solution of the flow field did not agree sufficiently with that by the Multiple Reference Frame (MRF) method, where the blade shape is highly-resolved. In order to solve the accuracy problem an irreversible loss, which has not taken into account in the original model, is considered in the present work by modeling the viscous dissipation near the blade surfaces. In addition, a geometrical fidelity of the rotating axis, which has been approximated with the cylinder, is improved by the use of a body-fitted function. The proposed method is validated by comparing the solutions obtained by the present method and that obtained by the MRF method. The relative errors are evaluated for the rotational velocity, the expansion ratio, temperature difference between the inlet and outlet, and the amount of energy loss. Both the modified points introduced in the present work are confirmed to contribute to accuracy improvement.

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In this study, the NH₃ oxidation reactivity of a Cu-chabazite SCR catalyst, which has a large impact on NOx purification characteristic at higher temperatures, was investigated using a synthetic gas bench. Detailed analyses by in-situ XAFS and DRIFTS were also performed to clarify the difference in reactions on Cu sites and Brønsted acid sites. Moreover we have developed a SCR reaction model considering the difference in reactions on these sites and showed this model can express the NOx purification phenomena at the high temperature range correctly.

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Fracture by tensile loading could be made cause in heat affected zone around the spot weld point. On this report, the flange shape which reduces the tensile stress was considered by 4 point bending test simulation. Concretely, some notches were given between the spot weld zone on the flange. Some analysis results of showed the fracture was restrained by the notches. Additionally, the better notch shape was considered based on the results.

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