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After the Great East Japan Earthquake on March 11, 2011, Toyota Motor Corporation received considerable public response regarding the role of vehicles in emergencies from a large number of customers. These included comments about the usefulness of the electricity supply system in the Estima Hybrid during the long power outages caused by the earthquake. In response, Toyota decided to install this system in its other hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs). This system is capable of supplying power up to 1,500 watts, which means that it can be used to operate virtually every household electrical device. Since the engine starts automatically when the main battery capacity is depleted, a single vehicle can supply the daily power needs of a normal house in Japan for about four days, providing that the battery is fully charged and the fuel tank is full.

A new combustion concept for DISI gasoline engine was developed to achieve superior performances of high power and low environmental load. It realizes a high specific power and a good lean combustion performance simultaneously by utilizing a DI spray jet effectively to accelerate the in-cylinder tumble flow. Injection direction and configuration of the DI spray was optimized for intensification of the in-cylinder flow and high mixture homogeneity, a thin fan-shaped spray generated by a slit nozzle was adopted. As a result, combustion was accelerated by increase of in-cylinder turbulence intensity, and homogeneity of air-fuel mixture was improved. In addition, in-cylinder fuel wall wetting, which causes emission of particulate matter (PM) and oil dilution, was drastically reduced by improvement of the fan-shaped spray.

The impact of fatty acid methyl ester (FAME) blended diesel fuel on engine/vehicle systems was comprehensively investigated by vehicle, laboratory and engine tests. In this study, 20% FAME blended fuel (B20) was mainly used and soy bean oil methyl ester (SME) was primarily selected as the FAME. Vehicle testing with long-term fuel storage in vehicle fuel tanks was conducted, considering the most severe conditions in market use. Laboratory and engine tests were also conducted to better understand the vehicle test results. In the vehicle test, engine startability, idle roughness and fuel injection control were evaluated using nine vehicles with plastic or metal fuel tanks. All vehicles showed no problems up to 7 months. While five vehicles with plastic fuel tank did not show any problems throughout the test period up to 18 months, four vehicles with metal fuel tanks experienced malfunctions in engine start or fuel injection control following 8, 13, 13 and 18 months respectively.

Exhaust and evaporative emissions systems have been developed to match the characteristics and usage of the Toyota THS II plug-in hybrid electric vehicle (PHEV). Based on the commercially available Prius, the Toyota PHEV features an additional external charging function, which allows it to be driven as an electric vehicle (EV) in urban areas, and as an hybrid electric vehicle (HEV) in high-speed/high-load and long-distance driving situations. To reduce exhaust emissions, the conventional catalyst warm up control has been enhanced to achieve emissions performance that satisfies California's Super Ultra Low Emissions Vehicle (SULEV) standards in every state of battery charge. In addition, a heat insulating fuel vapor containment system (FVS) has been developed using a plastic fuel tank based on the assumption that such a system can reduce the diffusion of vapor inside the fuel tank and the release of fuel vapor in to the atmosphere to the maximum possible extent.

The original Toyota Hybrid System (THS) was installed in the Prius and was introduced in 1997 as the world's first mass-produced hybrid passenger car. Since then, THS has been continuously improved. In 2003 THS-II (marketed as Hybrid Synergy Drive [HSD]), was installed in a new larger Prius. In 2006 HSD was installed in a Rear Wheel Drive Vehicle: the LEXUS GS450h. This system achieved both 4.5-liter class power performance and compact class fuel economy with outstanding emissions performance. In 2007, this system is expanded to a mechanical all-wheel-drive(AWD) in the LEXUS LS600hL(with new V8 engine). This paper will explain this hybrid system which achieved both V12 class power performance and mid-size class fuel economy, while meeting the most stringent emission standard SULEV as a full-size vehicle.

The original Toyota Hybrid System (THS) was installed in the Prius and was introduced in 1997 as the world's first mass-produced hybrid passenger car. THS has been continuously improved. In 2003 THS-II (marketed as Hybrid Synergy Drive [HSD]), was installed in a new larger Prius. In 2005 HSD was installed in two SUVs: the RX400h and Highlander Hybrid. This system achieved both V8 engine power performance and compact class fuel economy with outstanding emissions performance. In 2006, the HSD line-up is expanded to front-engine rear-wheel (FR) drive in the Lexus GS450h. This paper will explain this hybrid system which achieves both 4.5-liter class power performance and compact class fuel economy, while meeting the most stringent emission standard SULEV.

Toyota Hybrid System (THS), that combines a gasoline engine and an electric motor was installed in the Prius, which was introduced in 1997 as the world's first mass-produced hybrid passenger car, and was vastly improved in 2003. The new Prius gained a status of highly innovative and practical vehicle. In 2005, combined with a V6 engine, THS had a further evolution as a Hybrid System for SUV, which was installed in the RX400h and Highlander Hybrid to be introduced into the world. This report will explain “new THS” which achieved both V8 engine power performance and compact class fuel economy, while securing the most stringent emission standard, SULEV.

Toyota Hybrid System (THS), the powertrain that combines a gasoline engine and an electric motor was first introduced in December 1997. It became the first mass-produced hybrid passenger vehicle in the world, gaining a reputation as a highly innovative vehicle, and its cumulative worldwide sales have exceeded 120,000 units. In 2003, THS had a further evolution. The “new-generation Toyota Hybrid System (THS II)” would be introduced on the new Prius. This report shall explain “THS II”, which achieved drastic improvements in power performance and fuel economy, while securing the most stringent emission standard Advanced Technology Partial Zero Emission Vehicle (ATPZEV).

CARB (California Air Resources Board) has required the evaporative emissions to be restricted to 1/4th of the parameter stated in the 1995 regulations. Furthermore, hydrocarbons (hereafter, HC) from the fuel system must be reduced to near 0.0 grams, according to the PZEV (Partial Zero Emission Vehicle) regulations enforced from 2003. The wet film in intake ports and fuel leaking from the injector nozzles evaporate and diffuse while the car is parked, and consequently may cause HC to leak the air cleaner inlet. The air cleaner which prevents HC leakage from the air intake system is already in mass production. In the course of designing this product to be installed in a vehicle, the authors developed a method to estimate the amount of HC that reaches the air cleaner. Based on detailed investigation on HC distribution and the changes that occur during parking, the HC amount reaching the air cleaner was calculated by both the equation of diffusion and the equation of state.

The design of the newly developed Toyota AZ series 4 cylinder engine has been optimized through both simulations and experiments to improve heat transfer, cooling water flow, vibration noise and other characteristics. The AZ engine was developed to achieve good power performance and significantly reduced vibration noise. The new engine meets the LEV regulations due to the improved combustion and optimized exhaust gas flow. A major reduction in friction has resulted in a significant improvement in fuel economy compared with conventional models. It also pioneered a newly developed resin gear drive balance shaft.

The Vapor Reducing Fuel Tank System (Bladder Tank System) using a flexible plastic membrane (Bladder Membrane) was newly developed in order to reduce the amount of vaporized gasoline in a steel fuel tank. This Bladder Membrane is flexible to expand in proportion to a fuel volume and prevents the permeation of the vaporized gasoline. As a result of our initial study for various materials, we decided to apply a multi-layer plastic material which could achieve both low fuel permeability and good flexibility. This multi-layer material consists of polyethylene(PE) for structural material and polyamide(PA) for low permeability. The modulus of the PE needs to achieve a sufficient flexibility in order to keep the movement of the membrane. While PA material must have not only low fuel permeability but also strong adhesion with the structural material of PE. We also clarify the membrane design to keep a good flexibility and to reduce a strain.

In preparation for compliance with California's SULEV standard and Euro STAGE 4 standard, which will take effect in 2002 and 2005, respectively, we have developed a laminated planar oxygen sensor. The developed sensor has the following characteristics: high thermal conductivity and superior dielectric characteristic, due to direct joining of the heater element alumina substrate and the sensor element zirconia electrolyte; low heat stress at temperature rise, due to optimized heater design; superior sensor protection from water droplets, and improved sensor response, due to optimized arrangement of intake holes in the sensor cover. With these characteristics, the developed oxygen sensor can be activated in 10 seconds after cold start. This report describes the technologies we used to develop the early-activation oxygen sensor.

In succession to the world-first introduction of a mass production gasoline hybrid passenger car into the Japanese market in 1997, Toyota also has introduced an enhanced version of the above to the US and European markets in 2000. Upon introduction of Toyota Hybrid System (THS) into the US market, a drastic reduction of gasoline vapor evaporation from the fuel tank was necessary, in order to meet the most stringent exhaust emission (SULEV) and evaporative emission standards in the world. In order to meet this requirement, a fuel tank system named “Vapor Reducing Fuel Tank System” was developed. This is the first commercial application in the world to use a variable tank volume to drastically reduce gasoline vapor generation.

A new hybrid system has been developed which features a highly efficient, clean gasoline engine, and a high performance exhaust catalyst system. The new system meets the strictest low emission standards in the world, while realizing a major reduction in CO2 emissions. The Toyota Hybrid System (THS) has improved engine performance, transaxle transmission efficiency, and various vehicle improvements for improving fuel consumption. It also employs a high performance catalyst, a rapid catalyst warm-up strategy, Toyota HC Adsorber and Catalyst System (Toyota-HCAC-System) and a Vapor Reducing Fuel Tank System. These combined technologies allow for the achievement of U.S. California SULEV, European Step 4 and Japanese J-ULEV emission requirements. It has also lowered the CO2 level to less than 120g/km in EC European mode.

We urgently need to develop the next generation of automotive technology to support energy conservation and the global environment. For this we need an advancement of the Laboratory Automation System (LAS). However, restructuring the hardware and software of the LAS requires enormous amounts of time and costs. To solve the problems of the LAS development, we formed a user-vendor working group, which then established the common rules of LAS and IMACS (Integrated Measurement And Control System). IMACS are software-centered rules, characterized by the stratification of LAS and the interface called software parts. So far, we have integrated IMACS into five engineering fields. A total of 11 testing machine vendors participated in the development. We manufactured about 350 software parts and made their specifications openly available. As the next step, we are collecting software parts by deleting redundant functions.

In order to investigate the effect of sulfur and distillation properties on exhaust emissions, emission tests were carried out using a California Low Emission Vehicle (LEV) in accordance with the 1975 Federal Test Procedure ('75 FTP). To study the fuel effect on the exhaust emissions from different systems, these test results were compared with the results obtained from our previous studies using a 92MY vehicle for California Tier 1 standards and a 94MY vehicle for California TLEV standards. (1)(2) First, the sulfur effect on three regulated exhaust emissions (HC, CO and NOx) was studied. As fuel sulfur was changed from 30 to 300 ppm, the exhaust emissions from the LEV increased about 20% in NMHC, 17% in CO and 46% in NOx. To investigate the recovery of the sulfur effect, the test fuel was changed to 30 ppm sulfur after the 300 ppm sulfur tests. The emission level did not recover to that of the initial 30 ppm sulfur during three repeats of the FTP.

Detergent additives in automotive gasoline fuel are mainly designed to reduce deposit formation on intake valves and fuel injectors, but it has been reported that some additives may contribute to CCD formation. Therefore, a standardized bench engine test method for CCDs needs to be developed in response to industry demands. Cooperative research between the Petroleum Association of Japan (PAJ) and the Japan Automobile Manufacturers Association, Inc. (JAMA), has led to the development of a 2.2L Honda engine dynamometer-based CCD test procedure to evaluate CCDs from fuel additives. Ten automobile manufacturers, nine petroleum companies and the Petroleum Energy Center joined the project, which underwent PAJ-JAMA round robin testing. This paper describes the CCD test development activities, which include the selection of an engine and the determination of the optimum test conditions and other test criteria.

As a means of effectively incorporating the concept of “life cycle” for reducing the environmental impact of the automobile, we carried out a life cycle inventory study on a part-by-part basis. The targets of our study are the fuel tanks that are made of different materials and manufacturing processes. One is made of steel, and the other is made of plastic, both perform identical functions. Our evaluation study encompasses the period from the manufacturing of the main materials until the disposal of the tanks. The evaluation items consist of the amount of energy consumed and the emissions (of CO2, NOx, SOx, and PM) that are released into the atmosphere. The results show that the plastic tank poses a greater burden in terms of the amount of energy consumed and the CO2 and NOx emitted.

In order to satisfy future demands of low exhaust emission vehicles (LEV), a new fuel injection control system has been developed for SI engines with three-way catalytic converters. An universal exhaust gas oxygen sensor (UEGO) is mounted on the exhaust manifold upstream of the catalytic converter to rapidly feedback the UEGO output signal and a heated exhaust gas oxygen sensor (HEGO) is mounted on the outlet of the converter to achieve an exact air fuel ratio control at stoichiometry. The control law is derived from mathematical models of dynamic air flow, fuel flow and exhaust oxygen sensors (HEGO and UEGO). Experimental results on FTP (Federal Test Procedure) exhaust emissions show a dramatic reduction of HC, CO and NOx emissions and a possibility of practical low emission vehicles at low cost.

A highly accurate fuel sensing system has been developed which provides a digital indication of the remaining fuel on a l/P cluster. This system uses capacitance type sensors placed in the fuel tank to detect fuel level changes. This system uses three capacitance type sensors which enables it to determine highly accurate fuel level even in sloped surfaces. This fuel level sensor has been in production since 1991 and today is used on the TOYOTA SOARER in Japan.