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Trivalent chromium passivation is used after zinc plating for enhancing corrosion resistance of parts. In the passivating process, the amount of dissolved metal ions (for example zinc and iron) in the passivation solution increases the longer the solution is used. This results in a reduced corrosion resistance at elevated temperatures. Adding a top coat after this process improves the corrosion resistance but has an increased cost. To combat this, we strove to clarify the mechanism of decreased corrosion resistance and to develop a trivalent chromium passivation with a higher corrosion resistance at elevated temperatures. At first, we found that in parts produced from an older solution, the passivation layer has cracks which are not seen in parts from a fresh/new solution. These cracks grow when heated at temperatures over 120 degrees Celsius.

Measurements of residual stress in a printed circuit board, which consists of copper foil, silver alloy and thermo plastic resin, were conducted under a thermal cycle. The printed circuit board was given a ten-layer repeat of prepreg and made by thermocompression bonding. Experiments suggested the possibility of measuring surface residual stress of copper circuits and the internal residual stress of metallic connections by synchrotron radiation of Spring-8. FEM analysis of the printed circuit board during a thermal cycle was conducted, and the result was adjusted to X-ray stress using absorption correction. X-ray stress during a heat-cycle obtained by synchrotron radiation showed good agreement with stress calculated by FEM analysis.

Humidity sensors used in automatic windshield defogging controls contribute to the improvement of fuel consumption. The optimum control of air conditioning systems can be realized by adding humidity information to conventional systems which have used only temperature information. While resistive humidity sensors have been widely used, their sensing range and responsiveness are observed as issues. Resistive sensors cannot function at a humidity range of around 100% RH as well as at a low temperature range, and have a low response rate to sudden changes in humidity. It is considered that resistive humidity sensors will be replaced with capacitive ones which have a wide sensing range and high responsiveness.

In recent years, due to a growing demand for improvement in the performance and reliability of automotive fuel pumps and the advancement of globalization, automotive fuel pumps are being used with inferior gasolines that include more sulfur, organic acids or compounds, compared to gasolines used in general regions. Conventionally, bearings in these fuel pumps have mainly been made of sintered bronze alloy. With this bronze alloy, however, it is difficult to achieve a significant improvement in the tribology characteristics of bearings, in order to meet the demands for performance improvement, etc., and corrosion is severe in inferior gasolines that contain highly-concentrated organic acids or sulfur and the corrosion products that accompany them. Therefore, in order to obtain fine tribology characteristics and superior corrosion resistance in gasolines with highly-concentrated organic acids and sulfur, various copper-based alloys were studied using the powder metallurgy process.

PBT (polybutylene terephthalate) and epoxy adhesive, which both have superior heat resistance and environmental resistance, are a representative combination now being applied to many parts. Generally, PBT is annealed after molding at a temperature above the glass transition temperature to ensure dimensional stability when in use. But in this case, this process decreases the adhesive strength between PBT and epoxy. This study analyzes the adhesion degradation mechanism in this system and a countermeasure technology is proposed. Regarding this PBT-epoxy adhesion degradation mechanism, focus is placed on changes in the fracture surface, which is analyzed before and after annealing. From this analysis it becomes clear that generation of a WBL (weak boundary layer) is caused by non-crystallization and a migration of the PBT functional group on the adhesion surface layer.

In 1989, the first black face cluster was introduced as the first Lexus cluster and has been highly praised in the market. The cluster has strong advantages but could not gain a higher installation ratio in various vehicles because of the cost. DENSO Corp. has been improving the cost performance of this cluster and the installation ratio is being increased. On the other hand, multi-information displays and component integration in instrument panels will soon be introduced. Considering this, I would like to discuss the future trend of instrument clusters using the black face cluster concept with multi displays and integration capabilities.

Stringent emission regulations call for advanced catalyst substrates with thinner walls and higher cell density. However, substrates with higher cell density increase backpressure, thinner cell wall substrates have lower mechanical characteristics. Therefore we will focus on cell configurations that will show a positive effect on backpressure and emission performance. We found that hexagonal cells have a greater effect on emission and backpressure performance versus square or round cell configurations. This paper will describe in detail the advantage of hexagonal cell configuration versus round or square configurations with respect to the following features: 1 High Oxygen Storage Capacity (OSC) performance due to uniformity of the catalyst coating layer 2 Low backpressure due to the large hydraulic diameter of the catalyst cell 3 Quick light off characteristics due to efficient heat transfer and low thermal mass

The coming Diesel powertrains will remain as key technology in Europe to achieve the stringent 2025 CO2 emission targets. Especially for applications which are unlikely to be powered by pure EV technology like Light Duty vehicles and C/D segment vehicles which require a long driving range this is the case. To cope with these low CO2 targets the amount of electrification e.g. in form of 48V Belt-driven integrated Starter Generator (BSG) systems will increase. On the other hand the efficiency of the Diesel engine will increase which will result in lower exhaust gas temperatures resulting in a challenge to keep the required NOx reduction system efficiencies under Real Drive Emissions (RDE) driving conditions. In order to comply with the RDE legislation down to -7 °C ambient an efficient thermal management is one potential approach. Commonly utilized means to increase exhaust gas temperature are late injection and/or intake throttling, which enable sufficient NOx reduction efficiency.

In general, CFD analysis with porous media is precise enough to simulate airflow behavior in a heat exchanger core, placed in the vehicle. In a case when the airflow behavior is complex, however, the precision lowers according to our study. Therefore, we developed a new modeling method to keep high-precision and applied it to analysis of airflow in the vehicle. The concept is at first that the shape of tubes and the distance between the tubes are as the actual product so that the airflow with an oblique angle is to pass through a core. With this concept, airflow with an oblique angle hits the surface of tubes and passes through a core with changing the direction. Next, the concept is to reproduce the air pressure loss in actually-shaped fins, and therefore, we use a porous medium for the modeling of the fins instead of the product shape modeling to combine with the the tubes.

In the future, autonomous vehicles will be realized. It is assumed that traffic accidents will be caused by the overconfidence to the autonomous driving system and the lack of communication between the vehicle and the pedestrian. We propose that one of the solutions is a display system to give the information the state of vehicle to pedestrians. In this paper, we studied how the information influences the motion of pedestrians. The vehicle gives the information, which is displayed on road by using of color light (red, yellow and blue), of the collision risk determined by the TTC (Time to Collision). The pedestrian is ordered to cross the road in several cases of the TTC. In the presence of the TTC information, the number of the pedestrians, who did not cross the road in the case of short TTC (red light is displayed), increased from 52% to 67%. It is cleared that the pedestrians determined whether they crossed the road or not by the information effectively.

In automobiles, Integrated Starter Generators (ISGs) are important components since they ensure significant fuel economy improvements. With motors that operate at high voltage such as ISGs, it is important to accurately know partial discharge inception voltages (PDIVs) for the assured insulation reliability of the motors. However, the PDIVs vary due to various factors including the environment (temperature, atmospheric pressure and humidity), materials (water absorption and degradation) and voltage waveforms. Consequently, it is not easy either empirically or analytically to ascertain the PDIVs in a complex environment (involving, for example, high temperature, low atmospheric pressure and high humidity) in which many factors vary simultaneously, as with invehicle environments. As a well-known method, PDIVs can be analyzed in terms of two voltage values, which are the breakdown voltage of the air (called “Paschen curve”) and the shared voltage of the air layer.

Driving is an action that depends strongly on visual information. For displays in the cockpit, a combination of “ease of viewing” to inform the driver of danger early and “annoyance reduction” to avoid drops in the driver’s perception is needed. In this study, we tried to capture “ease of viewing” and “annoyance” in one fixed-quantity indicator. We took up a Camera Monitor System (CMS) as the subject and analyzed the effect that annoyance with the display used in CMSs has on driving behavior. Based on our analysis, we hypothesize that evaluating carelessness in viewing behavior is related evaluating to annoyance. Next, we chose a Detection Response Task (DRT) technique as a method to evaluate driving behavior influenced by this annoyance.

Alternator, which supplies electric energy to a battery and electrical loads when it is rotated by engine via belt, is one of key components to improve vehicle fuel efficiency. We have reduced rectification loss from AC to DC with a MOSFET instead of a rectifier diode. It is important to turn on the MOSFET and off during a rectification period, called synchronous control, to avoid a current flow in the reverse direction from the battery. We turn it off so as to remain a certain conduction period through a body diode of the MOSFET before the rectification end. It is controlled by making a feedback process to coincide with an internal target conduction period based on the rotational speed of the alternator. We reduced a voltage surge risk at turn-off by changing the feedback gain depending on the sign of the time difference between the measured period and the target.

This paper describes the reliability of silicon carbide (SiC) MOSFET. We clarified the relation between the lifetime of the gate oxide and the crystal defects. We fabricated MOS diodes using thermal oxidation and measured their lifetimes by TDDB (Time Dependent Dielectric Breakdown) measurement. The wear-out lifetime is sufficient for hybrid vehicle but many MOS diodes broke in shorter time. The breakdown points were defined by Photo-emission method. Finally, we classified the defects by TEM (Transmission Electron Microscopy). A TSD (Threading Screw Dislocation) plays the most important role in the lifetime degradation of the gate oxide. The lifetime of the gate oxide area, in which a TSD is included, is shorter by two orders of magnitude than a wear-out breakdown. The mechanism by which threading dislocations degrade the gate oxide lifetime was not discovered. To explain the degradation, we assumed two models, the shape effect and the oxide quality degradation.

The number of idle-stop vehicles is rapidly increasing in recent years, and air-conditioning technologies that extend engine stopped time while maintaining the cabin comfort are required. When the engine stops during idle- stop mode, the air conditioner also stops functioning. To maintain cabin comfort, the engine is restarted to work the air-conditioning cycle, which reduces the fuel saving effects. As a countermeasure, a cold storage air conditioning system has been proposed. The system extends engine non-operation time by using cold storage for generating cool air while the engine is stopped. We have integrated this technology into an evaporator, which is used in the air-conditioning cycle, and the system has a short cold storage period and a necessary cold release period. This report describes its concept and effects.

To comply with increasing fuel efficiency regulations, a low temperature radiator (LT radiator) is required to cool the charge-air system of a turbocharged engine. These engines are important to use for environmentally-friendly cars. Since heavy-duty and high-performance cars demand high cooling performance, the main radiator alone is typically insufficient in meeting the vehicle’s cooling requirements. An additional radiator installed in the front of the wheel-well is required to meet the extra cooling demand. In order to install this radiator in the front of the wheel-well, guaranteed performance in the limited packaging space and impact resistance of the leading tube edge are required. We developed the Supplementary Inner-Fin Radiator (SIR) which achieves the compact, high-performance, and durability requirements by use of an inner-fin tube (I/F tube). The purpose of this paper is to report our design approach and product specifications of the SIR.

As a method of maintaining thermal sensation and comfort inside a passenger compartment, not only a conventional HVAC system but also a combination of a HVAC system and other devices such as seat heaters, a steering wheel heater, ventilation seats are increasing. This research developed a method to evaluate thermal sensation of a human body when using these various thermal control devices. This method can evaluate the heat balance of the human body by calculating the amount of heat exchange between a human body and the external environment, and it takes into consideration the influence of heat exchange by heat conduction with seats or a steering wheel. The human thermal model is made by dividing a human body into various segments, and it is the model that considers heat transport by blood flow for each segment.

One of the main features of 48 V vehicles is the ability to coast at high speeds with the Internal Combustion Engine (ICE) off. This can be realized due to the high torque and power the 48 V motor-generator provides which allows a quick and smooth re-cranking of the ICE. The coasting feature reduces the fuel consumption depending on frequency and duration of the coasting events. This depends in turn on driving pattern, driving style, State-of-Charge of the 48 V and 12 V batteries and the air-conditioning (A/C) system. In summer, if the A/C runs with a mechanical belt-driven compressor, the cabin inlet air temperature from the evaporator inevitably increases during each coasting event as the ICE turns off and cannot operate the compressor. If the evaporator temperature reaches a certain threshold at which the cabin comfort is noticeably affected, the ICE is re-cranked for resuming air-conditioning.

Global exhaust emission regulations are becoming stricter, and vehicles equipped with the idle stop system (ISS) are increasing. Recently, starters for vehicles equipped with ISS are required to improve operation feel when speedily restarted. To satisfy this demand, starters must rotate at higher rotational speeds, and heavier wear in their brushes may cause problems. Tribofilm formed on commutators surface by the brush sliding is an important factor in the brush commutator wear, because tribofilm is said to have a property to increase lubricity and decrease mechanical wear in brushes and commutator, as well as to improve commutation and decrease arc wear. Therefore, for reducing brush commutator wear, it is considered effective to promote film formation by improving materials. However, few researches have been conducted to evaluate the relationship between brush materials and tribofilm formation.

In recent years, the spread of eco-car has led to the demand for adaptation to low heat source, high efficiency and low noise in vehicle air conditioner. On the other hand, larger interior space of vehicle to assure passenger comfort is demanded, so that the car air-conditioner is required to be smaller. Therefore, we adopted 2-layer HVAC for the air conditioner which can respond to a low heat source. At the same time we have developed the compact high-efficiency 2-layer blower fan for HVAC in order to enable the 2-layer HVAC to be mounted on eco-car with smaller space than conventional HVAC. Generally, because axial flow velocity increases resulting from downsizing of the blower, the ununiform velocity distribution in the axial direction and the turbulent flow between fan blades occurs. It causes the efficiency decrease. To satisfy both downsizing and high-efficiency of the 2-layer blower, we have developed new technologies which can make the flow uniform between fan blades.