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The purpose of this study is to propose braking characteristics that are easy for drivers to handle in a system in which braking and driving operations are performed by hand. Genetic algorithm optimization of braking characteristics showed that the best deceleration tracking was achieved by an FG diagram with a logarithmic function shape. In contrast, the slope of the optimal FG diagram tended to decrease as the driver's proportional gain increased.

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.

Reducing the carbon emissions associated with ICE- containing vehicles is a complimentary step towards carbon neutrality alongside the introduction of vehicles using newer energy vectors. In this study, the authors investigated emissions and efficiency impact of fully renewable E10-grade gasoline fuels blended with sustainable components at both 90 RON and 96 RON in comparison with reference regular E0 and premium certification gasolines across a range of ICE vehicle applications. Both renewable fuels were blended to the Japan JIS K2022 2012 E10 specification. The study shows very low carbon gasolines are technically feasible and potentially have an important role to play in decarbonizing both new advanced technology ICE vehicles and, critically, the existing ICE vehicle parc in the transition towards a zero emissions future.

The development of electric vehicles has been progressed, rapidly, to achieve Carbon neutrality by 2050. There have been increasing concerns about Electromagnetic Compatibility (EMC) performance due to increasing power for power trains of vehicles. Because same power train system expands to some vehicles, we have developed numerical simulations in order to predict the vehicle EMC performances. We modeled a vehicle which has inverter noises by numerical simulation to calculate electric fields based on GB/T18387. We simulated the common mode noise which flows through the shielding braid of the high voltage wire harnesses. As a result, it is confirmed a correlation between the electric fields calculated by numerical simulation and the measured one.

Contribution to carbon neutrality is one of the most important challenges for the automotive industry. Though CO2 emission has been reduced through electrification, internal combustion engines equipped in vehicles such as Hybrid Electric Vehicle (HEV) and Plug-in Hybrid Electric Vehicle (PHEV) are still necessary for the foreseeable future, and continuous efforts to improve fuel economy are demanded. To improve powertrain thermal efficiency, direct-injection turbocharged gasoline engines have been widely utilized in recent years. Super lean-burn combustion engine has been being researched as the next generation of turbocharged gasoline engines. It is known that an increase of the boost pressure causes deposit formation, which decrease the turbocharger efficiency, in the turbocharger compressor housing. To avoid the efficiency loss due to deposit, air temperature at compressor outlet has to be limited low.

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.

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.

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.

Nitric Oxide (NO) can significantly influence the autoignition reactivity and this can affect knock limits in conventional stoichiometric SI engines. Previous studies also revealed that the role of NO changes with fuel type. Fuels with high RON (Research Octane Number) and high Octane Sensitivity (S = RON - MON (Motor Octane Number)) exhibited monotonically retarding knock-limited combustion phasing (KL-CA50) with increasing NO. In contrast, for a high-RON, low-S fuel, the addition of NO initially resulted in a strongly retarded KL-CA50 but beyond the certain amount of NO, KL-CA50 advanced again. The current study focuses on same high-RON, low-S Alkylate fuel to better understand the mechanisms responsible for the reversal in the effect of NO on KL-CA50 beyond a certain amount of NO.

To achieve carbon neutrality by reducing carbon dioxide (CO2) emissions, vehicles with an internal combustion engine have started to be replaced by electrification vehicles such as hybrid electric vehicles (HEVs), plug-in HEVs (PHEVs), and battery EVs (BEVs) worldwide, which have motors in their transaxles (T/As). Reducing transmission torque loss in the transaxles is effective to reduce CO2 emissions, and lowering the viscosity of lubrication fluids in T/As is a promising method for reducing churning and drag loss. However, lowering viscosity generally leads to thin oil films and makes the lubrication condition severe, resulting in worse anti-fatigue and anti-seizure performance. To deal with these issues, we made improvements on the additive formulation of fluid, such as the addition of an oil-film-forming polymer, chemical structure change of calcium detergents, and an increase of anti-wear additives including phosphorus and sulfur.

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.

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.

Toyota developed a new hybrid unit “L4A0” for the new Tundra, which creates both good drivability and environmental performance. To ensure off-road, towing performance and typical truck driving characteristics, the unit is based on a transmission with a torque converter and a multi-plate lock up clutch, with a motor-generator and K0 clutch installed between the engine and transmission. The motor-generator and K0 clutch are built into a module, making it possible to create new hybrid units by combining the module with various transmissions. The unit features many different motor controls. For example, in the case of step-in acceleration input, in order to achieve the desired output torque, typically a kick-down shift is necessary [1]; however, by utilizing “L4A0” both high response and high power output is achieved even without a kick-down shift. This is accomplished by assisting the engine with the motor-generator even when the engine torque is delayed at low engine speeds.

The reduction of CO2 emissions is one of the most important challenges for the automotive industry to contribute to address global warming. Reducing friction of internal combustion engines (ICEs) is one effective countermeasure to realize this objective. The improvement of engine oil can contribute to reduce fuel consumption by reducing friction between engine parts. Electrification of ICE powertrains increases the overall efficiency of powertrains and reduces the average engine oil temperature during vehicle operation, due to intermittent engine operation. An effective way of reducing engine friction is to lower the viscosity of the engine oil in the low to medium temperature range. This can be accomplished while maintaining viscosity at high temperatures by reducing the base oil viscosity and increasing the viscosity modifier (VM) content to raise the viscosity index (so-called “flat viscosity” concept).

In recent years, the realization of carbon neutrality has become an activity to be tackled worldwide, and automobile manufacturers are promoting electrification of power train by HEV, PHEV, BEV and FCEV. Although interest in BEV is currently growing, vehicles equipped with internal combustion engines (ICE) including HEV and PHEV will continue to be used in areas where conversion to BEV is not easy due to lack of sufficient infrastructures. For such vehicles, low-viscosity engine oil will be one of the most important means to contribute to further reduction of CO2 emissions. Since HEV requires less work from the engine, the engine oil temperature is lower than that of conventional engine vehicles. Therefore, the reduction of viscous resistance in the mid-to-low temperature range below 80°C is expected to contribute more to fuel economy. On the other hand, the viscosity must be kept above a certain level to ensure the performance of hydraulic devices in the high oil temperature range.

Due to new CO2 regulations and increasing demand for improved fuel economy, reducing aerodynamic drag has become more critical. Aerodynamic drag at the rear of the vehicle accounts for approximately 40% of overall aerodynamic drag due to low base pressure in the wake region. Many studies have focused on the wake region structure and shown that drag reduction modifications such as boattailing the rear end and sharpening the rear edges of the vehicle are effective. Despite optimization using such modifications, recent improvements in the aerodynamic drag coefficient (Cd) seem to have plateaued. One reason for this is the fact that vehicle design is oriented toward style and practicality. Hence, maintaining flexibility of design is crucial to the development of further drag reduction modifications. The purpose of this study was to devise a modification to reduce rear drag without imposing additional design restrictions on the upper body.

In recent years, GPFs (Gasoline particulate filters) have been installed in gasoline engines to comply with stricter environmental regulations in China and Europe. In particular, coated-GPFs having a catalytic purification function are required to have high conversion performances, high filter efficiencies in the sense of a high collection efficiency, and low pressure loss. It is not easy to design a filter that satisfies all these parameters. Experimental studies are being conducted, but it is costly to study in trial productions. In this technical paper, a GPF design optimization method will be proposed that combines multi-scale simulation, surrogate models by machine learning, and an optimization algorithm. By using this method, a GPF design that minimizes pressure loss while providing high conversion performance and particle collection rates that satisfy current regulations can be created.

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.