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To adapt to Battery Electric Vehicle (BEV) integration, the significance of protective designs for battery packs against ground impact caused by road debris is very high, and there is also a keen interest in the feasibility assessment technique using Computer-Aided Engineering (CAE) tools for prototype-free evaluations. However, the challenge lies in obtaining real-world empirical data to verify the accuracy of the predictive CAE model. Collecting real-world data using actual battery pack can be time-consuming, costly, and accurately ascertaining the precise direction, magnitude, and location of the force applied from the road to the battery pack poses a challenging task. Therefore, in this study, we developed a methodology using machine learning, specifically Gaussian process regression (GPR), to perform inverse analysis of the direction, magnitude, and location of vehicle-road contact forces during rough road conditions.

Reducing vehicle CO2 emissions is an important measure to help address global warming. To reduce CO2 emissions on a global basis, Toyota Motor Corporation is taking a multi-pathway approach that involves the introduction of the optimal powertrains according to the circumstances of each region, including hybrid electric (HEVs) and plug-in hybrid electric vehicles (PHEVs), as well as battery electric vehicles (BEVs). This report describes the development of a new PHEV system for the Toyota Prius. This system features a traction battery pack structure, transaxle, and power control unit (PCU) with boost converter, which were newly developed based on the 2.0-liter HEV system. As a result, the battery capacity was increased by 1.5 times compared to the previous model with almost the same battery pack size. Transmission efficiency was also improved, extending the distance that the Prius can be driven as an EV by 70%.

Toyota has developed a new 2.4L L4 turbo (2.4L-T) engine with 8AT and 1-motor hybrid electric powertrains for midsize pickup trucks. The aim of these powertrains is to fulfill both strict fuel economy and emission regulations toward “Carbon Neutrality”, while exceeding customer expectations. The new 2.4L L4 turbocharged gasoline engine complies with severe Tier3 Bin30/LEVIII SULEV30 emission regulations for body-on-frame midsize pickup trucks improving both thermal efficiency and maximum torque. This engine is matched with a newly developed 8-speed automatic transmission with wide range and close step gear ratios and extended lock-up range to fulfill three trade-off performances: powerful driving, NVH and fuel economy. In addition, a 1-motor hybrid electric version is developed with a motor generator and disconnect clutch between the engine and transmission.

This paper describes the development of a new e-AWD hybrid system developed for SUVs. This hybrid system consists of a high-torque 2.4-liter turbocharged engine and a front unit that contains a 6-speed automatic transmission, an electric motor, and an inverter. It also includes a rear eAxle unit that contains a water-cooled high-power motor, an inverter, and a reduction gear, as well as a bipolar nickel-metal hydride battery. By combining a turbo engine that can output high torque across a wide range of engine rpm with two electric motors (front and rear), this system achieves both smooth acceleration with a torquey driving feeling and rapid response when the accelerator pedal is pressed. In addition, new AWD control using the water-cooled rear motor realized more stable cornering performance than the previous e-AWD system.

This paper describes a new control technology that coordinates the operation of multiple actuators in a new hybrid electric vehicle (HEV) system consisting of a turbocharged engine, front and rear electric motors, two clutches, and a 6-speed automatic transmission. The development concept for this control technology is to achieve the driver’s desired acceleration G with a natural feeling engine speed. First, to realize linear acceleration G even while the engine is starting from EV mode, clutch hydraulic pressure reduction control is implemented. Furthermore, the engine start timing is optimized to prevent delayed drive force response by predicting the required maximum power during cranking. Second, to realize linear acceleration, this control selects the proper gear position based on the available battery power, considering noise and vibration (NV) restrictions and turbocharging response delays.

In 2022, Toyota launched new battery electric vehicle (BEV), the Toyota bZ4X. Unlike gasoline-powered vehicles, BEVs require charging. Users want increased range and shorter charging times. bZ4X's charging system increased range and shortened AC/DC charging time compared to the Lexus UX300e launched in 2020. A new unit called Electricity Supply Unit (ESU) was developed that integrated a DCDC converter, on-board charger, DC relays, and a branch box for power distribution function into a single unit. The design moved the branch box out of the battery pack to make room for the battery capacity, and it integrated the power conversion function into a single unit, making it more compact than if each unit were mounted separately. A 7 kW or 11 kW on-board charger is included with the vehicle. The 7 kW on-board charger is inside ESU; the 11 kW charger is external to the ESU.

Toyota has launched a new BEV which incorporates our newest evolutions in BEV powertrain systems and vehicle platform innovations. The new BEV uses newly developed large format battery cells, which, in addition to achieving our key performance and safety targets, also incorporates new technologies resulting in improved battery energy density and a reduction in battery deterioration. For the BEV battery cooling, to enhance safety, the cooling plate and the battery cells are separated by a chamber structure. The battery pack also incorporates a newly developed high resistance coolant with low conductivity. The new BEV improves system efficiency by leveraging some technologies that were originally developed for HEV and developing new systems. For example, radiant heating and a newly developed heat pump system improve EV driving range. This presentation will introduce our new battery technologies and discuss our new BEV system.

It is necessary for us to reduce CO2 emissions in order to hold down global warming which is advancing year by year. Toyota Motor Corporation believes that not only the introduction of BEVs but also the sale of the hybrid vehicles must spread in order to achieve the necessary CO2 reduction. Therefore, we planned to improve the attractiveness of future hybrid vehicles. Prius has always made full use of hybrid technologies and leading to significant CO2 reduction. Toyota Motor Corporation has developed a 2.0L hybrid system for the new Prius. We built the system which could achieve a comfortable drive along following the customer’s intention while improving the fuel economy more than a conventional system. The engine improves on both output and thermal efficiency. The transaxle decreases mechanical loss by downsizing the differential, and adoption of low viscosity oil.

The new Toyota Mirai hydrogen fuel cell electric vehicle (FCEV) was launched in December 2020. Achieving a low-cost, high-performance FC stack is an important objective in FCEV development. At the same time, it is also necessary to ensure vehicle safety. This paper presents an overview of the safety requirements for onboard FC stacks. It also describes the simulation and evaluation methods for the following matters related to the FC stack. i) Impact force resistance: The FC stack was designed to prevent cell layer slippage due to impact. Constraint force between the cell layers is provided by the frictional force between the cells and an external constraint. A simulation of the behavior of the cell layers under impact force was developed. The impact force resistance was confirmed by an impact loading test. ii) Hydrogen safety: The FC stack was designed so that permeated hydrogen is ventilated and the hydrogen concentration is kept below the standard.

Since the regulations of CO2 emissions have been tightened in each country recently, each automotive manufacturer has responded by bringing competitive technologies that maximize efficiency while promoting vehicle electrification such as xEV. Not only the efficiency, we need to meet or exceed occupant performance and comfort expectations. The climate control system expends a large amount of energy to keep a comfortable environment, having a significant impact on fuel consumption and EV driving range. Therefore, many manufacturers try to save energy and improve occupant comfort quickly by using not only the conventional convective heating by HVAC but also the conductive heating to heat the human body directly such as seat and steering wheel heater. In this study, a radiative heater, which is more efficient than a convective heating to warm anterior thigh and shin where a conductive heating cannot warm, was applied to vehicle.

This paper proposes a technology to reduce vehicle surge during towing that utilizes motors and shifting to help ensure comfort in a parallel HEV pickup truck. Hybridization is one way to reduce fuel consumption and help realize carbon neutrality. Parallel HEVs have advantages in the towing, hauling, and high-load operations often carried out by pickup trucks, compared to other HEV systems. Since the engine, motor, torque converter, and transmission are connected in series in a parallel HEV, vehicle surge may occur when the lockup clutch is engaged to enhance fuel efficiency, similar to conventional powertrains. Vehicle surge is a low-frequency vibration phenomenon. In general, the source is torque fluctuation caused by the engine and tires, with amplification provided by first-order torsional driveline resonance, power plant resonance, suspension resonance, and cabin resonance. This vibration is amplified more during towing.

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.

All-solid-state lithium (Li)-ion batteries have attracted significant interest for their enhanced energy density compared with conventional batteries employing an organic liquid electrolyte. However, the interfacial impedance and reaction between electrodes and the electrolyte can hinder the transport of Li-ions, thus degrading the battery performance. This paper presents a systematic screening method to identify coatings to reduce impedance and maintain interface stability during battery operation. Promising coating materials are rapidly selected by evaluating properties for ideal coating materials from computational databases containing a vast collection of Li compounds. Finally, a few candidates are discovered and their battery performances are tested. This approach is demonstrated to be an efficient way to predict and evaluate functional coatings for a high performance all-solid -state battery design.

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).

In order to improve the fuel efficiency of Hybrid Electric Vehicles (HEVs), it is necessary to reduce the size and power loss of the HEV Power Control Units (PCUs). The loss of power devices (IGBTs and FWDs) used in a PCU accounts for approximately 20% of electric power loss of an HEV. Therefore, it is important to reduce the power loss while size reduction of the power devices. In order to achieve the newly developed PCU target for compact-size vehicles, the development targets for the power device were to achieve low power loss equivalent to its previous generation while size reduction by 25%. The size reduction was achieved by developing a new RC-IGBT (Reverse Conducting IGBT) with an IGBT and a FWD integration. As for the power loss aggravation, which was a major issue due to this integration, we optimized some important parameters like the IGBT and FWD surface layout and backside FWD pattern.

Toyota Motor has developed a new compact class hybrid vehicle (HV). This vehicle incorporates a new hybrid system to improve fuel efficiency. For this system, a new power control unit (PCU) has been developed that is downsizing, lightweight, and high efficiency. It is also important to have a highly adaptable function that can be applied to various car models. This paper describes the development of PCUs that play an important role in new systems.

Automobile manufactures need to adopt new technologies to meet global CO2 (carbon dioxide) emission regulations and better fuel efficiency demands from customers. Also, the production cost should be as low as possible for an affordable vehicle. Therefore, it is advantageous for OEMs to develop fuel efficient technologies which can be controlled by software without additional hardware costs. The coasting control is a fuel efficiency improvement technology that can be implemented by the change of vehicle software only. The coasting control is a technology that reduces the driving resistance (Deceleration) when the driver releases the gas pedal. This technology leads to reducing the energy required for the vehicle to drive and results in improving the real-world fuel economy. In an internal combustion engine (ICE) vehicle, the coasting state is achieved by changing the gear to neutral, and the effect has been discussed and clarified by many previous studies.

Toyota has developed a new Hybrid (HV) transaxle P810 for Mid-Size SUVs to improve fuel efficiency and power performance. The transaxle was developed based on Toyota's new development strategy - Toyota New Global Architecture (TNGA). By adopting technologies to shorten overall length of the transaxle, installation into the same engine compartment of Mid-Size sedans have been realized while also improving the motor output. This paper will introduce technologies regarding the new mount structure for shortening overall length, and furthermore, noise reduction related to this mount structure.

Toyota Motor Corporation has developed new Hybrid Vehicle (HV) and Plug in Hybrid Vehicles (PHV) from Compact class to Medium class. These vehicles incorporate newly developed hybrid systems for the improvement of fuel efficiency. The feature of these new generation power control unit is smaller, lighter, and higher efficiency than the previous generation. To adapt to various output systems, a development strategy of new generation Power Control Unit (PCU) was established. Based on the strategy, the development efficiency was improved. In this Paper, the strategy is described.

Given a forecast of speed and load demands during a trip, a hybrid powertrain power-split Trajectory Optimization Problem (TOP) can be solved to optimize fuel consumption. This can be done on desktop to set performance benchmarks; however, it has been believed that the TOP could not be solved in real-time and is not a realizable controller. As such, several approximations of the TOP have been made in the interest of obtaining a real-time near-optimal controller, for example, Equivalent Consumption Minimization Strategies (ECMS) and their adaptive counterparts. These strategies decide on the power-split by, at each sampled time instant, minimizing a Horizon-0 (without predicting forward in time) composite function of fuel consumption and equivalent battery energy. The fuel economy that results from these strategies is highly sensitive to the calibration of the associated equivalence factor, and furthermore, must be chosen differently for different drive cycles.