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In the 1st generation Toyota "MIRAI" fuel cell stack, carbon protective surface coating is deposited after individual Ti bipolar plate being press-formed into the desired shape. Such a process has relatively low production speed, not ideal for large scale manufacturing. A new coating concept, consisting of a nanostructured composite layer of titanium oxide and carbon particles, was devised to enable the incorporation of both the surface treatment and the press processes into the roll-to-roll production line. The initial coating showed higher than expected contact resistance, of which the root cause was identified as nitrogen contamination during the annealing step that inhibited the formation of the composite film structure. Upon the implementation of a vacuum furnace chamber as the countermeasure, the issue was resolved, and the improved coating could meet all the requirements of productivity, conductivity, and durability for use in the newer generation of fuel cell stacks.

Teammate Advanced Drive is a driving support system with state-of-the-art automated driving technology that has been developed for customers’ safe and secure driving on highways based on the Toyota’s Mobility Teammate Concept. This SAE Level 2 (L2) system assists overtaking, lane changes, and branching to the destination, in addition to providing hands-free lane centering and car following. The automated driving technology includes self-localization onto a High Definition Map, multi-modal sensing to cover 360 degrees of the surrounding environment using fusion of LiDARs, cameras, and radars, and a redundant architecture to realize fail-safe operation when a malfunction or system limitation occurs. High-performance computing is provided to implement deep learning for predicting and responding to various situations that may be encountered while driving.

Collisions between opened doors and approaching vehicles such as bicycles are common occurrences in urban areas around the world. For example, in Chicago, 20% of all bicycle accidents involve collisions with doors, which occur over 300 times a year. In addition, there are concerns about a further rise in accidents due to the recent increase in home delivery services and bicycle commuting during the COVID-19 pandemic. Some advanced driver assistance systems (ADAS) that are designed to help prevent this type of accident have already been introduced. These systems detect approaching vehicles with sensors and alert the person opening the door via LED lights or a buzzer when the door is opened. The occupant must understand the meaning of the alert and stop opening the door quickly to prevent an accident. However, if the occupant is an elderly person or a child, it is difficult to stop opening the door quickly.

In recent years, electrically heated catalysts (EHCs) have been developed to achieve lower emissions. In several EHC heating methods, the direct heating method, which an electric current is applied directly to the catalyst substrate, can easily activate the catalyst before engine start-up. The research results reported on the use of the direct heating EHC to achieve significant exhaust gas purification during cold start-up [1]. From the perspective of catalyst loading, ceramics is considered to be a better material for the substrate than metal due to the difference in coefficient of thermal expansion between the catalyst and the substrate, but the EHC made of ceramics has difficulties such as controllability of the current distribution, durability and reliability of the connection between the substrate and the electrodes.

Since bumper reinforcements are positioned at front/rear ends of vehicles, weight reduction of the bumper reinforcements enhances vehicle dynamic performance by reducing a yaw moment of inertia. CFRP (Carbon Fiber Reinforced Plastic) composites are attractive lightweight materials due to their excellent specific strength and rigidity. However, because of their relatively high cost, applications of CFRP materials to vehicle structural parts are limited. In this study we have developed a lightweight, structural part, which consists of a thin-walled Al (Aluminum) bumper reinforcement with a UD (Unidirectional)-CFRP sheet. The intention is to prevent an increased part cost by reducing the amount of Al and by minimizing the amount of CFRP. Compared to Al, UD-CFRP sheets have even higher tensile strength and modulus. When vehicles crash, bumper reinforcements may be subjected to bending force.

Further fuel economy improvement of the internal combustion engine is indispensable for CO2 reduction in order to cope with serious global environmental problems. Although lowering the viscosity of engine oil is an effective way to improve fuel economy, it may reduce the wear resistance. Therefore, it is important to achieve both improved fuel economy and reliability. We have developed new 0W- 8 engine oil of ultra-low viscosity and achieved an improvement in fuel economy by 0.8% compared to the commercial 0W-16 engine oil. For this new oil, we reduced the friction coefficient under boundary lubrication regime by applying an oil film former and calcium borate detergent. The film former increased the oil film thickness without increasing the oil viscosity. The calcium borate detergent enhanced the friction reduction effect of molybdenum dithiocarbamate (MoDTC).

This paper describes the development of a simplified fracture finite element (FE) model for resistance spot welds (RSW) of ultra-high-strength steel (UHSS) that can be incorporated into large-scale vehicle FE model. It is known that the RSW of UHSS generates two types of fracture modes: heat-affected zone (HAZ) and nugget zone fractures. Lap shear and peeling coupon tests using UHSS sheets found that the different RSW fracture modes occurred at different nugget diameters. To analyze this phenomenon, detailed simulated coupon tests were carried out using solid hexahedral elements. The analytical results revealed that RSW fractures are defined by both the application of plastic strain on the elements and the stress triaxiality state of the elements. A detailed model incorporating a new fracture criteria model recreated the different UHSS RSW fracture modes and achieved a close correlation with the coupon test results.

Silver metallic colors with thin and smooth aluminum flake pigments have been introduced for luxury brand OEMs. Regarding the paint formulation for these types of colors, low non-volatile(NV) and high aluminum flake pigment contents are known as technology for high metallic appearance designs. However, there are two technical concerns. First is mottling which is caused by uneven distribution of the aluminum flake pigments in paint film and second is poor film property due to high aluminum pigment concentration in paint film. Therefore, current paint systems have limitation of paint design. As a countermeasure for those two concerns, we had investigated cellulose nanofiber (CNF) dispersion liquid as both the coating binder and rheology control agent in a new type of waterborne paint system. CNF is an effective rheology control agent because it has strong hydrogen bonds with other fiber surfaces in waterborne paint.

Application of SiC power devices is regarded as a promising means of reducing the power loss of power modules mounted in power control units. Due to those high thermostable characteristics, the power module with SiC power devices are required to have higher operating temperature than the conventional power module with Si power devices. However, the limitations of current packaging technology prevent the utilization of the full potential of SiC power devices. To resolve these issues, the development of device bonding technology is very important. Although transient liquid phase (TLP) bonding is a promising technology for enabling high temperature operation because its bonding layer has a high melting point, the characteristics of the TLP bonding layer tend to damage the power devices. This paper describes the development of a bonding technology to achieve high temperature operation using a stress reduction effect.

Growing concerns about the depletion of raw materials as vehicle ownership continues to increase is prompting automakers to look for ways of decreasing the use of platinum-group metals (PGMs) in the exhaust systems. This research has developed a new catalyst with strong robustness against fluctuations in the exhaust gas and excellent nitrogen oxide (NOx) conversion performance. One of the key technologies is a new OSC material that has low surface area (SA) and high OSC performance. We enhanced the pyrochlore- ceria/zirconia (CZ) which has a very small SA. In order to enhance the heat resistance and promote the OSC reaction, we selected and optimized the additive element. This material showed high OSC performance especially in the temperature range of 400 degrees or less. Another key technology is washcoat structure that has high gas diffusivity by making connected pore in the washcoat (New pore forming technology).

The tendency for car engines to reduce the cylinder number and increase the specific torque at low rpm has led to significantly higher levels of low frequency pulsation from the exhaust tailpipe. This is a challenge for exhaust system design, and equally for body design and vehicle integration. The low frequency panel noise contributions were identified using pressure transmissibility and operational sound pressure on the exterior. For this the body was divided into patches. For all patches the pressure transmissibility across the body panels into the interior was measured as well as the sound field over the entire surface of the vehicle body. The panel contributions, the pressure distribution and transmissibility distribution information were combined with acoustic modal analysis in the cabin, providing a better understanding of the airborne transfer.

In an effort to reduce mass, future automotive bodies will feature lower gage steel or lighter weight materials such as aluminum. An unfortunate side effect of lighter weight bodies is a reduction in sound transmission loss (TL). For barrier based systems, as the total system mass (including the sheet metal, decoupler, and barrier) goes down the transmission loss is reduced. If the reduced surface density from the sheet metal is added to the barrier, however, performance can be restored (though, of course, this eliminates the mass savings). In fact, if all of the saved mass from the sheet metal is added to the barrier, the TL performance may be improved over the original system. This is because the optimum performance for a barrier based system is achieved when the sheet metal and the barrier have equal surface densities. That is not the case for standard steel constructions where the surface density of the sheet metal is higher than the barrier.

The renewed platform of the upcoming flagship front-engine, rear-wheel drive (FR) vehicles demands high levels of driving performance, fuel efficiency and noise-vibration performance. The newly developed driveline system must balance these conflicting performance attributes by adopting new technologies. This article focuses on several technologies that were needed in order to meet the demand for noise-vibration performance and fuel efficiency. For noise-vibration performance, this article will focus on propeller shaft low frequency noise (booming noise). This noise level is determined by the propeller shaft’s excitation force and the sensitivity of differential mounting system. In regards to the propeller shaft’s excitation force, the contribution of the axial excitation force was clarified. This excitation force was decreased by adopting a double offset joint (DOJ) as the propeller shaft’s second joint and low stiffness rubber couplings as the first and third joints.

Emission regulations in many countries and regions around the world are becoming stricter in reaction to the increasing awareness of environment protections, and it has now become necessary to improve the performance of catalytic converters to achieve these goals. A catalytic converter is composed of a catalytically active material coated onto a ceramic honeycomb-structured substrate. Honeycomb substrates play the role of ensuring intimate contact between the exhaust gas and the catalyst within the substrate’s flow channels. In recent years, high-load test cycles have been introduced which require increased robustness to maintain low emissions during the wide range of load changes. Therefore, it is extremely important to increase the probability of contact between the exhaust gas and catalyst. To achieve this contact, several measures were considered such as increasing active sites or geometrical surface areas by utilizing substrates with higher cell densities or larger volumes.

Increasing numbers of vehicles equipped with downsized, turbocharged engines have been introduced seeking for better fuel economy. LSPI (low speed pre-ignition), which can damage engine hardware, is a potential risk of the engines. We reported that engine oil formulation affects frequency of LSPI events, and formulating magnesium detergents into oil is a promising option to prevent LSPI events. From the viewpoint of achieving better fuel economy by engine oil, lowering viscosity is being required. However, it causes reduced oil film thickness and will expand boundary lubrication condition regions in some engine parts. Hence, a technology to reduce friction under boundary lubrication becomes important.

A highly anti-corrosive organic-inorganic hybrid paint for automotive steel parts has been developed. The inorganic component included in the paint is silicon dioxide (SiO2), which has the capability to passivate zinc. By application of the paint on a trivalent chromatetreated zinc-plated steel sheet or a trivalent chromate-treated zinc-nickel-plated steel sheet, high anti-corrosion protection can be provided to steel materials. Particularly in the case of application over a zinc-nickel-plated steel sheet, 0 mm corrosion depth after a cyclic corrosion test (CCT) of 450 cycles was demonstrated.

The dissolution and exfoliation of chromium plating specific to Russia was studied. Investigation and analysis of organic compounds in Russian soil revealed contents of highly concentrated fulvic acid. Additionally, it was found that fulvic acid, together with CaCl2 (a deicing agent), causes chromium plating corrosion. The fulvic acid generates a compound that prevents reformation of a passivation film and deteriorates the sacrificial corrosion effectiveness of nickel.

The use of a head-up display (HUD) system has become popular recently, as it can provide feedback information at a position easily seen by the driver. However, the outline of the HUD bezel often reflects on the windshield of a HUD equipped vehicle. This phenomenon occurs when the sun is at a high position and reflects off the top of the instrument panel and the front view is dark. For this reason, it can occur when driving on asphalt paved roads, causing annoyance to the driver. Under fixed environmental conditions, the vehicle based factors that influence the annoyance caused by reflected boundary lines are the position of the reflection, line thickness, and the contrast of the reflected boundary line. These can be represented by the conspicuity of a striped pattern (contrast sensitivity function). In previous research in 1991, M. S. Banks et al. studied a contrast sensitivity function that included the factors stated above.

Replacing the metal car roof with conventional solar modules results in the increase of total car weight and change of center of mass, which is not preferable for car designing. Therefore, weight reduction is required for solar modules to be equipped on vehicles. Exchanging glass to plastic for the cover plate of solar module is one of the major approaches to reduce weight; however, load bearing property, impact resistance, thermal deformation, and weatherability become new challenges. In this paper a new solar module structure that weighs as light as conventional steel car roofs, resolving these challenges is proposed.

This paper describes the development of a fatigue life prediction method for Laser Screw Welding (LSW). Fatigue life prediction is used to assess the durability of automotive structures in the early design stages in order to shorten the vehicle development time. The LSW technology is a spot-type joining method similar to resistance spot welding (RSW), and has been developed and applied to body-inwhite structures in recent years. LSW can join metal panels even when a clearance exists between the panels. However, as a result of this favorable clearance-allowance feature of LSW, a concave shape may occur at the nugget part of the joint. These LSW geometric features, the concavity of nuggets and the clearance between panels, are thought to affect the local stiffness behavior of the joint. Therefore, while assessing the fatigue life of LSW, it is essential to estimate the influence of these factors adequately for the representation of the local stiffness behavior of the joint.