A modeling method for spray combustion with a real fuel is proposed and validated. A total of 22 species are defined as palette species for the modeling of market fuels based on two-dimensional gas chromatography and hydrogen nuclear magnetic resonance spectroscopy. A surrogate fuel model is formulated to best reproduce the distillation curve and the reactivity of the real fuel. Large-eddy simulations are performed for spray combustion with the surrogate fuel model. The results showed that a local hot spot develops into ignition with the equivalence ratios raging from one to six, indicating that the modeling of reaction and mixing at fuel rich side is significantly important.

View full abstract

White smoke emission is observed at tailpipe of diesel engine when unburned hydrocarbons (HCs) are stored on diesel oxidation catalyst (DOC) under low gas temperatures. In this research, it was investigated that effects of HCs adsorbed on alumina and zeolite coated on DOC for white smoke emission by change of zeolite content and specific surface area (SSA) of alumina. HCs poisoning on platinum group metal (PGM) may occur by rapid HCs desorption from zeolite and degrade the HCs oxidation performance of DOC, leading to white smoke emission. Therefore, adopting small SSA alumina to DOC can reduce the adsorbed HCs amount on alumina inhibiting HCs poisoning on PGM, thus improve HCs oxidation performance. This improvement achieved not only the reduction in white smoke emission but also the improvement of HCs and carbon monoxide clarification during New European Driving Cycle mode compared to conventional DOC specifications.

View full abstract

In Direct Injection Spark Ignition engines, the fuel atomization is one of the most effective factors in characteristics of combustion and emissions. The characteristics of the fuel spray are known to be affected by cavitating flow inside the nozzle hole. In this paper, to clarify the effect of hole angle on cavitation inside the nozzle and liquid jet, observation of flow inside the nozzle and liquid jet were carried out for various injection pressure by using enlarged nozzle with the hole angle. The images of cavitation and liquid jet are taken using a high speed video camera.

View full abstract

Diesel fuel reformations have been suggested to extend the operational ranges of premixed diesel combustion. In this research, the diesel fuel is reformatted by the piston compression of rich mixture in the reformation cylinder and the thermal conversion conditions of reformatted gases, hydrogen, carbon monoxide, and methane, were first investigated by the chemistry dynamics simulation (CHEMKIN pro). Based on the calculated results, the diesel engine was operated under the rich mixture conditions. Throughout this research, it was found that the composition of reformatted gas can be estimated by the maximum cylinder temperature.

View full abstract

A comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometer (GCxGC-TOFMS) was used for analysis of gas composition in a constant volume combustion chamber before ignition. Influences of mixture temperature on reaction products from toluene/O₂/Ar were investigated by varying mixture temperature from 450 to 510K. From the detected signal of benzaldehyde, it was indicated that oxidation reaction of toluene was accelerated by temperature rising. From comparison between toluene/O₂/Ar and 20mol%toluene+80mol%n-heptane/O₂/Ar, it was indicated that the reaction of n-heptane accelerated the consumption of toluene. In addition, it was suggested that heptanedione was important product of low temperature reaction of alkanes.

View full abstract

Urea SCR system is effective post treatment device of diesel engine to remove NOx in exhaust gas. The purpose of this study is constructing simulation model capable of predicting spray behavior and NH₃ concentration distribution. In order to achieve the purpose, it is necessary to clarify urea solution spray behavior injected by Urea SCR injector and concentration distribution of NH₃ generated by chemical reaction in experimental analysis. In this report, NH₃ generating process is clarified by understanding urea solution spray behavior and NH₃ concentration distribution in high temperature flow field.

View full abstract

We developed a damping device that used a magneto-rheological (MR) fluid, whose yield stress varies with applied magnetic field intensity. The device consists of two rotating disks with the MR fluid between them. It reduces vibrations by varying the viscosity of the fluid, and thus the moment of inertia of the rotating bodies, by controlling the magnetic field using the current in a stator coil. When this device was applied to the flywheel of a hybrid vehicle, it reduced the energy needed to start the engine, and improved the engine response.

View full abstract

In this paper, we evaluate replacement from a gasoline vehicle(GV) to an electric vehicle(EV) and introduction of Vehicle-to-Home(V2H) from an economic point of view. V2H is a system that supplies electricity from a Lithium ion battery(LiB) of the EV to home. We use a dynamic model of the LiB for economic evaluation. For efficient evaluation, we propose a method in which we construct a database about various EV operating conditions using the LiB model and select appropriate data from the database for a given operating condition.

View full abstract

When driving on uneven road, the road input causes a vehicle various motions. Although the studies on bounce and pitch responses to road input in the view point of ride comfort have been reported, there are not a lot of analyses of lateral, yaw and roll responses on uneven road. In this paper, these responses to road input during turning was focused. A hypothesis about the phenomenon were formulated and were verified.

View full abstract

In pedestrian protection, the effect of difference in body shape on injury measures has not been studied. An obese FE model was developed and injury measures were compared against a model representing an average male to examine the influence of pedestrian body shape on injury measures. In addition, the influence of car body shape and the body weight of a pedestrian were also investigated. As a result, the effects of these factors were quantitatively clarified.

View full abstract

The objective of the study is to clarify how driving experience using ACC system affects an elderly driver in adaptation of ADAS. We simulated a car platoon including ACC-ON and ACC-OFF vehicles as the drive experience situation in the study on the test track. The drive experience was conducted at the test track with a 2,700m oval track in Tomakomai City, Japan. 32 drivers (aged 65 to 79 years; 11 females and 21 males) participated in the drive experience with ACC system. the drive experience with ACC-ON vehicle increased adaptation of ADAS for Elderly Drivers. Most participants answered positive subjective assessments rather than those before the drive experience of ACC-ON vehicle. However, sudden system-off of ACC system while driving lowered the evaluations on the ADAS vehicle.

View full abstract

To respond to the needs for utilizing information safely while driving, we studied a system that controls useful information properly in response to driving workload. First, we devised a new method which adds the correction by individual differences to VACP that is the method of estimating workload uniquely from characteristics of driving workload. Secondly, we verified the effectiveness of the system that controls information based on the new method by implementing the system into driving simulator.

View full abstract

The contribution ratio of indoor climate (CRI)—an index of the spatial distribution of the thermal influence of heat sources—has previously been proposed as a means to estimate the individual contribution of heat sources to the temperature field in a room. In the present study, the CRI was used to predict the distribution of air temperature in vehicle cabins, and this simple prediction method was validated. Both convective and radiant heat transfer coefficients were calculated through computational fluid dynamics modeling, following which the entire thermal environment was evaluated. The equivalent temperature was predicted using prior knowledge of only the CRI and the airflow velocity. The results can be applied to increase the efficiency and decrease the energy consumption of air-conditioning systems.

View full abstract

Influence of effect factors for measuring fuel consumption of fuel cell vehicles was studied by testing a mass product type vehicle. Effect factors were extracted and divided into the factors originated from the facilities for hydrogen supply and the factors originated from their drive batteries. The measuring method for fuel consumptions in this paper was based on the World wide harmonized Light vehicles Test Procedure (WLTP). The fuel consumptions were measured by driving with the Worldwide Light-duty Test Cycles (WLTC). Their influence of the factors on fuel consumptions were quantitatively compared.

View full abstract

Recently, the vehicle emissions measurement is required not only under test cycle conditions but also under real driving conditions. Especially, the real driving emissions (RDE) regulation will be applied from September 2017 in Europe, and a solid particle number portable emissions measurement system (PEMS-PN) was developed. In order to obtain the high performance of PEMS-PN, the correlation with the reference system was evaluated before RDE tests and the PEMS-PN was used to determine the PN emission behavior under real-driving conditions.

View full abstract

Fuel consumption characteristics in automobiles depend on those types of propulsion system and driving patterns. In this study, typical propulsion system models were coupled with virtual test driving tool and those fuel consumptions at real world driving patterns were estimated as a result. Fuel consumptions at type approval test procedure are also estimated. Furthermore, those conformities of propulsion system with driving pattern are solved and possibility of CO₂ emission reduction in Real-world Driving Emissions.

View full abstract

A new cutting force simulator, which calculates discretely uncut chip thickness based on fully voxel representation of cutting edge and instantaneous workpiece shape, has been developed to predict cutting force for corner radius end mill. In this cutting force simulator, it is possible to detect the uncut chip thickness between the complex workpiece shape and the special cutting edge shape such as corner radius end mill. Experimental milling tests using a corner radius end mill were conducted for the verification of this cutting force simulation. Predicted milling forces have good agreement with measured milling forces.

View full abstract

In order to improve the self-localization accuracy of autonomous driving vehicles, we have developed the processing system of LiDAR scan data utilizing the landmark information stored in Advanced map. The data processing system consists of three contents: the optimal prediction window for landmark detection, determination of reliability information of landmark measurement, and adaptive Kalman gain according to the generated reliability information. The experimental results confirmed that high accurate self-localization can be realized with above technologies. After that, from the simulation assuming by using forward scan type LiDAR, we calculated the accuracy of the estimated position and confirmed the sufficient performance. In addition, we studied how to update of landmark information. Simulation results of them indicated that utilizing the cloud server will make possible the update of landmark information.

View full abstract

Verification and validation of large-scale and complicated automotive control systems remains a major challenge. Regarding this challenge, we have developed search based testing (SBT), that is the verification method to search for input scenarios that lead to undesirable behavior. Although SBT is useful as a verification method applicable to large-scale and complicated systems, input scenarios not suitable for actual development process are often detected, and it causes an increase in work man-hours. To realize the efficient search, we developed a novel SBT with input scenario evaluator based on the driving conditions distribution obtained from the real driving data.

View full abstract