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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.

Recently, automakers have launched various types of electric vehicles (EVs) to help reduce global CO₂ emissions and reduce dependency on fossil fuel energy. Because the lithium-ion batteries that are currently under development are restricted by energy density, the physical size and mass of the battery must be significantly increased to extend the cruising range of the EV. Furthermore, dedicated charging infrastructure is required to charge the battery in a short time. At SAE in 2012, Toyota Motor Corporation proposed a concept that described the EV as suitable mainly for short-distance transportation now and in the near future. Later in the same year, Toyota launched a new EV that embodies this concept in the American and Japanese markets. This new EV is light-weight and has a compact body size, and its battery capacity is designed to sufficiently cover distances traveled in daily life. Charging is assumed to take place mainly at home.

Over the past decades, the automotive industry has made significant efforts to improve engine fuel economy by reducing mechanical friction. Reducing friction under cold conditions is becoming more important in hybrid vehicle (HV) and plug-in hybrid vehicle (PHV) systems due to the lower oil temperatures of these systems, which results in higher friction loss. To help resolve this issue, a new internal gear fully variable discharge oil pump (F-VDOP) was developed. This new oil pump can control the oil pressure freely over a temperature range from -10°C to hot conditions. At 20°C, this pump lowers the minimum main gallery pressure to 100 kPa, thereby achieving a friction reduction effect of 1.4 Nm. The developed oil pump achieves a pressure response time constant of 0.17 seconds when changing the oil pressure from 120 kPa to 200 kPa at a temperature of 20°C and an engine speed of 1,600 rpm.

To improve the fuel economy and dynamic performance of hybrid electric vehicles (HVs), Toyota Motor Corporation has boosted the voltage of the hybrid system. Increases in system voltage have to be matched by increases in the breakdown voltage of the Free Wheeling Diodes (FWD) in that system. However, using conventional technology to accomplish this causes a temporary decrease in breakdown voltage during switching, leading to increased device losses. It was found that this phenomenon was being caused by the unexpected generation of crystal defects, the reduction of which has enabled device losses to be suppressed. (Reported at ISPSD 2006.)

In order to improve air quality and to reduce urban noise, Toyota Motor Corporation has developed a fuel cell hybrid bus, FCHV-BUS2, in cooperation with HINO Motors, Ltd. The FCHV-BUS2 is based on a HINO low floor city bus model, and powered by a hydrogen fuel cell hybrid system. Hydrogen is stored in high pressure tanks on the bus roof. Based on the Toyota fuel cell hybrid technology for passenger cars, this fuel cell hybrid bus is equipped with two fuel cell stacks, two traction motors and four secondary batteries, making its vehicle efficiency approximately 1.7 times better than the diesel engine powered bus. The vehicle efficiency is boosted by charging the secondary batteries with regenerated energy while deceleration and by stopping the fuel cell stack(s) power generation during low fuel cell power modes.

Improving vehicle fuel economy is a central part of efforts toward achieving a sustainable society. An effective way of accomplishing this is to enhance the engine thermal efficiency. Mitigating knock and reducing engine heat loss are important aspects of enhancing the thermal efficiency. Cooled exhaust gas recirculation (EGR) is regarded as a key technology because it is capable of achieving both of these objectives. For this reason, it has been adopted in a wide range of both hybrid vehicles and conventional vehicles in recent years. In EGR equipped engines, fast combustion is regarded as one of the most important technologies, since it realizes higher EGR ratio. To create fast combustion, generation of strong in-cylinder turbulence is necessary. Strong in-cylinder turbulence is achieved through swirl, squish, and tumble flows. Specifically high tumble flow has been adopted on a number of new engines because of the intense effect of promoting in-cylinder turbulence.

Low pressure loop (LPL) EGR systems are effective means of simultaneously reducing the NOx emissions and fuel consumption of diesel engines. Further lower emission levels can be achieved by adopting a system that combines LPL EGR with a NOx storage and reduction (NSR) catalyst. However, this combined system has to overcome the issue of combustion fluctuations resulting from changes in the air-fuel ratio due to EGR gas recirculation from either NOx reduction control or diesel particulate filter (DPF) regeneration. The aim of this research was to reduce combustion fluctuations by developing LPL EGR control logic. In order to control the combustion fluctuations caused by LPL EGR, it is necessary to estimate the recirculation time. First, recirculation delay was investigated. It was found that recirculation delay becomes longer when the LPL EGR flow rate or engine speed is low.

A low sulfated ash (S.Ash) DL-1/C2 0W-30 diesel engine oil with improved fuel economy has been developed to meet the PM targets outlined in the Euro 5 emissions standards and to help achieve the voluntary European CO2 target of 140 g/km. The newly developed engine oil is an effective solution to the trilemma (triple probrem) of reliability (high detergency and high anti wear), low S.Ash, and fuel economy, achieving a fuel economy improvement of 2% and reducing CO2 emissions by 3 g/km.

1 In order to reduce the size and weight of the hybrid motor, improving motor cooling performance is essential. Therefore, we have been working on the development. This paper will explain the development of cooling technology TOYOTA has been working on, specifically the evolution of the hybrid motor cooling system and structure from the 1st generation Prius to the current model.

In recent years, attention has been focused on a hybrid vehicle capable of substantial reductions in CO2 exhaust emissions. This paper describes the newly developed 1.8-liter 2ZR-FXE gasoline engine for use with a hybrid system for compact vehicles, which effectively combines higher driving performance with higher fuel efficiency. This engine was based on the 1.8-liter 2ZR-FE engine with outstanding performance and fuel efficiency. This engine has achieved high thermal efficiency by using the high-expansion ratio cycle “Atkinson cycle”, as with the previous 1NZ-FXE engine. Additionally, a new cooled Exhaust Gas Recirculation (EGR) system and electric water pump were adopted to further improve fuel efficiency. A high efficiency cooler was used to cool the EGR gas, which enabled the introduction of the EGR gas at high load conditions, and exhaust gas temperature was reduced.

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%.

An unique diesel engine electronic control system has been developed, which contains two distinctive features. Firstly, the delivery type fuel injection pump has an electro-magnetic valve to control the quantity of fuel injected. This valve is then acutuated to ensure that the timing of the high pressure fuel flow out stops the fuel injection. In the previous diesel electronic control system, the fuel quantity control was effected via the position control of a mechanical spill ring. Since timing control is more suitable than position control for handling by a microcomputer, the electro-magnetic valve is able to control the quantity of fuel injected more precisely, whilst consisting of a simpler structure. Secondly, an optical combustion timing sensor is able to detect initial combustion timing by sensing the light of the combustion flame in the combustion chamber. Using the signal from the sensor, the microcomputer then exerts a compensating control over the fuel injection timing.

Recently, due to mounting concerns regarding the environment and energy conservation, demand for compact and hybrid vehicles with good fuel economy has been increasing. Toyota Motor Corporation has developed its first hybrid transaxle for installation in sub-compact class vehicles. This new hybrid transaxle is both smaller and lighter than the P410 hybrid transaxle for compact class vehicles, including the 2009 Prius. This was accomplished by creating new designs of the gear train, motor, and motor cooling system, and by adopting advanced technology. This paper describes the major features and performance of this transaxle in detail.

The world is currently facing environmental issues such as global warming, air pollution, and high energy demand. To mitigate these challenges, the electrification of vehicles is essential as it is effective for efficient fuel utilization and promotion of alternative fuels. The optimal approach for electrification varies across different markets, depending on local energy conditions and current circumstances. Consequently, Toyota has taken the initiative to offer a comprehensive lineup of battery electric vehicles (BEV), hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), and fuel cell electric vehicles (FCEV), aiming to provide sustainable solutions tailored to the unique situations and needs of each region. As part of this effort, Toyota has developed the 5th generation of hybrid electric vehicles. This paper describes the electric motor used in the new Toyota Camry which achieves high torque, high power, low losses, and compact design.

A next-generation plug-in hybrid system has been developed for the new Prius Prime. The objective of this development was to maximize the performance of the Toyota Hybrid System II (THS II) developed for the new fourth generation Prius HV, while achieving even better dynamic performance in electric vehicle (EV) mode. These objectives were accomplished by the adoption of new components and systems, as well as refinements to existing hybrid vehicle (HV) components. This paper describes the development of this new plug-in hybrid system.

To help respond to growing customer demand for environmentally friendly vehicles, a new transaxle for plug-in hybrid vehicles (PHVs) has been developed that achieves excellent fuel economy and ensures high performance when the PHV operates in electric vehicle (EV) mode. Under the basic concept of sharing a large number of parts with the transaxle in the all new Prius, the newly designed PHV transaxle was developed with the aim of enhancing EV power and range. To achieve our goal, the new transaxle uses a Dual Motor Drive System that operates the generator as a motor to supplement the existing motor. It also features an electrical oil pump (EOP) that improves cooling performance in EV mode. The developed transaxle helps to advance the PHV as a key next-generation environmentally friendly vehicle by maximizing the performance of the Toyota Hybrid System (THS) and achieving even better dynamic EV mode performance than the new Prius HV.

There is increasing demand for highly functional diesel engine turbochargers capable of meeting Euro 6 emissions regulations while improving dynamic performance and fuel economy. However, since these requirements cannot be easily satisfied through refinements of existing technology, Toyota Motor Corporation has developed the new D-series turbocharger for initial installation in its GD diesel engine. The higher efficiency and wider operation range of the new turbocharger enabled the amount of the turbine flow capacity to be reduced by 30%, while helping to improve dynamic response and fuel economy. The mechanism causing the generation of fuel deposits in the fuel injection system upstream of the turbocharger, which was adopted for compliance with emissions regulations, was analyzed and fundamental countermeasures were applied. The result is a new highly functional turbocharger with greatly enhanced reliability.

In recent years, many various energy sources have been investigated as replacements for traditional automotive fossil fuels to help reduce CO₂ emissions, respond to instabilities in the supply of fossil fuels, and reduce emissions of air pollutants in urban areas. Toyota Motor Corporation considers the plug-in hybrid vehicle, which can use electricity efficiently, to be the most practical current solution to these issues. For this reason, Toyota began sales of the Prius plug-in hybrid in early 2012 in both the U.S. and Japan. This is the first plug-in hybrid vehicle to be mass-produced by Toyota Motor Corporation. Prior to this, in December 2009, Toyota sold 650 plug-in hybrid vehicles through lease programs for verification testing in the U.S., Europe, and Japan. The system of the recently launched mass-produced vehicle underwent major improvements in response to the results of this verification testing. As a result, EV range was increased with a smaller battery.

Toyota Motor Corporation has developed the new compact-class hybrid vehicle (HV). This vehicle incorporates Toyota Hybrid System II (THS-II) to improve fuel efficiency. For this system we have developed a new power control unit (PCU) that features size reduction, light weight, and high efficiency. We have also improved the ability to mass produce these units with the expectation of rapid popularization of HV. The PCU, which plays an important role in THS-II, is our main focus in this paper. Its development is described.

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.