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Carbon neutrality has become a significant target. One essential parameter regarding energy consumption and emissions is the mass of vehicles. Lightweight design improves the result of vehicle life cycle assessment (LCA), increases efficiency, and can be a step towards sustainability and CO2 neutrality. Weight reduction through structural optimization is a challenging task. Typical design development procedures have to be overcome. Instead of just a facelift or the creation of a derivative of the predecessor design, completely alternative design creation methods have to be applied. Automated structural optimization is one tool for exploring completely new design approaches. Different methods are available and weight reduction is the focus of topology optimization. This paper describes a fatigue life homogenization method that enables the weight reduction of vehicle parts. The applied CAE process combines fatigue life prediction and topology optimization.

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.

HEV and PHEV require an improved aftertreatment system to clean the exhaust gas in various driving situations. The efficiency of aftertreatment system is significantly influenced by the residence time of the gas in a catalyst which gas flow has generally strong pulsation. Simulation showed up to 70% reduction of exhaust gas emission if the pulsation could be completely attenuated. A new concept exhaust manifold was designed to minimize pulsation flow by wall impingement, with slight increase of pressure loss. Experimental results with new concept exhaust manifold showed exhaust gas emission were reduced 16% at cold condition and 40% at high-load condition.

Global focus on CO2 reduction and environmental protection is increasing. To comply with stricter exhaust gas regulations and reduce real world emissions, it is becoming increasingly important to improve the performance of three-way catalysts. Therefore, highly efficient conversion of hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) is required. In general, the more active the precious metals used, the better the conversion performance. However, precious metals have supply risks, such as price fluctuation and the uneven distribution of production areas. Therefore, it is necessary to lower emissions while also lowering the amount of precious metals used. This paper focuses on how catalysts are used and describes the development of a new three-way catalyst for the purpose of strengthening cold conversion and decreasing the usage of precious metals.

To prevent global warming, many countries are making efforts to reduce CO2 emissions toward achieving 2050 carbon neutrality. In order to reduce CO2 concentration quickly, in addition to spread of renewable energy and expansion of BEV, it is also important to reduce CO2 emissions by improving thermal efficiency of ICE (internal combustion engine) and utilizing carbon neutral fuels such as synthetic fuels and biofuels. It is well known that lean burn is an effective technology to increase thermal efficiency of engine highly. However, since NOx emission from lean burn engine cannot be reduced with three-way catalyst, there have been issues such as complicated system configuration due to the addition of NOx reduction catalyst or limiting lean operation to narrow engine speed and load in order to meet emission regulation of each country.

This paper presents a design method for continuous fiber composites in three-dimensional space with locally varying orientation distribution and 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 a CNC embroidery machine prepares the preform. 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.

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.

This paper describes the high-pressure hydrogen storage system developed for new FCV. With the aim of further popularizing FCVs, this development succeeded in improving the performance of the system and reducing costs. This new storage system consists of multiple tanks of different sizes, which were optimized to store the necessary amount of hydrogen without sacrificing the interior space of the vehicle. The new tanks achieved one of the highest volume efficiencies in the world by adopting high-strength carbon fiber, developed in conjunction with the carbon fiber manufacturer, and by optimizing the layered construction design which allowed the amount of carbon fiber to be reduced. To increase the amount of available hydrogen, the longer high pressure tanks were mounted under the vehicle floor unlike the previous model. This was accomplished by the following two measures: First, individual design and manufacturing measures for the tanks were adopted.

The first MIRAI was launched in 2014 as the world’s first commercial fuel cell vehicle (FCV) [1]. Compared to the FC stack used in the first MIRAI, the FC stack in the new MIRAI achieved one of the highest volumetric power densities in the world (5.4 kW/L, excluding end plates, 1.5 times higher than the FC stack in the first MIRAI) by adopting a new flow channel for the bipolar plate and an improved electrode [2]. Enhancing the current density is an important means of increasing power performance and reducing size. The bipolar plate functions to distribute gas and drain water inside the cells to stabilize current generation. However, a conventional straight flow channel tends to cause flooding, which makes it difficult to maintain stable current generation. A partially narrow flow channel was developed to enhance oxygen diffusion without the 3D fine-mesh flow field that was adopted in the previous FC stack.

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.

In order to achieve the Toyota Environmental Challenge of 2050 (zero CO2 emissions), we have developed an innovative coating system that achieves more than 95% transfer efficiency. In order to reduce paint loss in the painting process, it is necessary to eliminate overdust and bounce dust. The most important point is how to spray (atomization, particle flight, adhesion) without shaping air. We have developed a “super high transfer efficiency system” that eliminates the need for shaping air. We continue to challenge the development of innovative technologies to view the paint shop as clean and eco-friendly environment.

Further improvements in catalyst performance are required to help protect the atmospheric environment. However, from the viewpoint of resource availability, it is also necessary to decrease the amount of precious metals used at the active sites of the catalyst. Therefore, a high-performance three-way catalyst with an advanced coating layer has been developed to lower the amount of precious metal usage. Fuel efficiency improvement technologies such as high compression ratios and a large-volume exhaust gas recirculation (EGR) generally tend to increase the ratio of hydrocarbons (HC) to nitrogen oxides (NOx) in exhaust gas. This research focused on the palladium (Pd) loading depth in the coating layer with the aim of improving the hydrocarbon (HC) conversion activity of the catalyst.

The knock-suppression effectiveness of exhaust-gas recirculation (EGR) can vary between implementations that take EGR gases after the three-way catalyst and those that use pre-catalyst EGR gases. A main difference between pre-and post-catalyst EGR gases is the level of trace species like NO, UHC, CO and H2. To quantify the role of NO, this experiment-based study employs NO-seeding in the intake tract for select combinations of fuel types and compression ratios, using simulated post-catalyst EGR gases as the diluent. The four investigated gasoline fuels share a common RON of 98, but vary in octane sensitivity and composition. To enable probing effects of near-zero NO levels, a skip-firing operating strategy is developed whereby the residual gases, which contain trace species like NO, are purged from the combustion chamber. Overall, the effects of NO-seeding on knock are consistent with the differences in knock limits for preand post-catalyst EGR gases.

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.

1 Structural parts, such as the center pillar, are a multi-layer structure. They are a combination of high-strength panels and high-toughness panels, to control the deformation mode during a crash. If we can make this multi-layered structure as one panel, consisting of different hardness within it, we will be able to make a lightweight part. In this study, we have developed a method to fabricate a ‘lightweight center pillar’ with the following processes. First, the whole panel is hardened by quenching within the hot stamp process. Next, certain areas of the panel are softened by partial tempering. We have found that the temperature zone for softening is between A1 and A3, and it is easy to perform a rapid and accurate tempering by utilizing induction heating around the Curie temperature between A1 and A3 transformation temperature.

Wireless Power Transfer (WPT) promises automated and highly efficient charging of electric and plug-in-hybrid vehicles. As commercial development proceeds forward, the technical challenges of efficiency, interoperability, interference and safety are a primary focus for this industry. The SAE Vehicle Wireless Power and Alignment Taskforce published the Recommended Practice J2954 to help harmonize the first phase of high-power WPT technology development. SAE J2954 uses a performance-based approach to standardizing WPT by specifying ground and vehicle assembly coils to be used in a test stand (per Z-class) to validate performance, interoperability and safety. The main goal of this SAE J2954 bench testing campaign was to prove interoperability between WPT systems utilizing different coil magnetic topologies. This type of testing had not been done before on such a scale with real automaker and supplier systems.

To resolve two major problems of conventional CFD-based shape optimization technology: (1) dependence of the outcome on the selection of design parameters, and (2) high computational costs, two types of innovative inverse analysis technologies based on a mathematical theory called the Adjoint Method were developed in previous studies for maximizing an arbitrary hydrodynamic performance aspect as the cost function: surface geometry deformation sensitivity analysis to identify the locations to be modified, and topology optimization to generate an optimal shape. Furthermore, these technologies were extended to transient flows by the application of the transient Adjoint Method theory. However, there are many cases around flow path shapes in vehicles where performance with respect to heat or concentration, such as the total amount of heat transfer or the flow rate of a specific gas component, is very important.

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).