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A multi-dimensional numerical method for predicting the warm-up characteristic of automobile catalytic converter systems was developed to effectively design catalytic converter systems which achieve low tail pipe emissions with satisfactory packagebility. The features of the method are; (1) consideration of the governing phenomena such as gas flow, heat transfer, and chemical reactions (2) capability of predicting warm-up characteristic for not only the catalytic converters but also the system as a whole during emission test modes such as the USA LA-4 mode. The description of the method is presented. The experimental verifications of the method were conducted to assure the accuracy of it. The effect of design parameters such as electrically heated catalyst (EHC), high loading of noble metal and thin honeycomb wall on warm-up characteristic of the catalyst are analyzed in the paper.

In the field of automotive body electronic control such as control of door locks, power windows, and wipers, there is a growing need of multiplexing communication to reduce the amount of wire harnesses. To meet this need, we developed a multiplexing communication protocol particularly suited to the body electronic control. Based on the developed protocol, we designed a communication control IC and a simple driver/receiver circuit with a few discrete components. The bus access method of the communication is the CSMA/CD with nondestructive bit arbitration, and its bit rate is 5 kbps. Its transmission media is a single wire. The communication IC has a multiplexing control block and a serial I/O block for an interface with a host CPU. It was fabricated using CMOS technology and has a chip of 2.6mm x 3.0mm in size that contains about 5,000 transistors. The driver/receiver circuit consists of one transistor, one capacitor and several resistors.

Development of a new battery system for Toyota Estima Hybrid, the world's first minivan hybrid vehicle, has been completed. The battery pack that consists of 30 nickel metal hydride battery modules is compactly arranged under the 3rd seat in the cabin along with components such as the battery cooling blower and the ducts. This arrangement was designed in consideration of user's vehicle use, passengers' comfort and efficient battery-cooling performance.

In this paper, the authors have developed a new measuring method of the liquid fuel film thickness on walls, such as intake ports, the combustion chamber and cylinder liner of a Port Fuel Injection (PFI) engine, and clarified the fuel film behavior under various running conditions when Fiber-based Laser-Induced Fluorescence (Fiber-based LIF) was applied to the newly developed method. The thickness of the fuel film is measured by detecting the intensity of fluorescence from the film that is irradiated by a He-Cd laser. A single optical fiber is used to simultaneously transmit the laser beam and the fluorescence from the film. In addition, the S/N ratio of the fluorescence is improved by using a He-Cd laser of which the wavelength (λ=442nm) is able to efficiently irradiate test fuel doped 2-3-butandione. Using this method, the fuel film thickness on the wall of the PFI engine was analyzed in two case studies.

Environmental improvement is moving forward, due in part to the reduction of fuel consumption of automatic transmission(AT) vehicles as a result of social requirements in recent years and many measures have been implemented. Adoption of idling stop is a typical example introduced to reduce energy consumption while the vehicle is stopped to improve the urban environment. However, there are problems such as responsiveness and smoothness for an AT vehicle when the engine is stopped with the shift selector in “D” range. To overcome these problems, a new start clutch control system has been developed using an electric oil pump installed in a simple hybrid vehicle called a mild hybrid. As a result, a smooth feeling starting performance is achieved by operating the system in combination with the engine and other systems.

Toyota Motor Corporation has been actively pursuing the development of fuel cell vehicles (FCVs) to respond to global environmental concerns and demands for clean energy. Toyota developed the first fuel cell (FC) bus to receive vehicle type certification in Japan. Subsequently, a new FC bus has been developed, which adopts two FC systems and four high-voltage batteries to achieve the required high power performance and durability. For enhanced durability, the FC system is controlled to maximize usage of the high-voltage batteries and to reduce the number of electric potential changes of the fuel cell. To accomplish this, the voltage of the FC stack must be kept high and FC power must be kept low. The high-voltage batteries were used to actively minimize FC power during acceleration.

The outline of the TOYOTA FCHV-adv is described in this paper. The TOYOTA FCHVadv achieved an approximately 25 percent improvement in vehicle fuel efficiency and about 1.9 times the amount of usable hydrogen in comparison with the previous model. These improvements have enabled almost 2.5 times longer practical cruising range, more than 500 km. The freeze start capabilities of the FCHV-adv were improved by modifying the FC stack and control system. As a result, the FCHV-adv has been capable of starting at a temperature of -30°C. In the future, TOYOTA intends to improve durability and reduce costs.

Toyota Motor Corporation developed the Fuel Cell Hybrid Vehicle (FCHV). The FCHV-4 is an evolution of the conventional fuel cell vehicle that has made immense improvements in efficiency. Both a fuel cell and a secondary battery are used as sources of energy for the hybrid system. By using these energy sources proportionally, the system can be kept at or near its optimum state. The FCHV-4's system is designed to improve the efficiency and aims for high responsiveness when the vehicle is in a transitional state. In the same way as most electric vehicles, and as in the gasoline powered hybrid “Prius”, the energy the traction motor creates during breaking can be used to regenerate the secondary. The fuel cell and traction motor inverter are connected directly, with the secondary battery connected through the DC/DC converter to the fuel cell in parallel.

The new Toyota FCV “Mirai” has reduced the weight, size, and cost of the high-pressure hydrogen storage system while improving fueling performance. The four 70 MPa tanks used on the 2008 Toyota FCHV-adv were reduced to two new larger diameter tanks. The laminated structure of the tanks was optimized to reduce weight, and a high-strength low-cost carbon fiber material was newly developed and adopted. The size of the high-pressure valve was reduced by improving its structure and a high-pressure sensor from a conventional vehicle was modified for use in a high-pressure hydrogen atmosphere. These innovations helped to improve the weight of the whole storage system by approximately 15% in comparison with Toyota FCHV-adv, while reducing the number of component parts by half and substantially reducing cost. The time required to fuel the FCV was greatly reduced by chilling the filling gas temperature at the hydrogen filling station to −40°C (as per SAE J2601).

This paper contains an explanation of a Multiplex Wiring System with Optical Data-Link for cars, which has been installed in the Toyota “Century” since 1982. In this system, a total of 64 signals related to door wiring are transmitted in a multiplex fashion, and the number of wires from the front right-hand door to the interior could be reduced from 46 wires, which were used with conventional wiring techniques, to 10 wires including 2 plastic optical fibers. This system also has various control functions which includes a door-lock control function. In order to give high reliability to this system, we have developed a new optical data-link as well as a new custom micro-computer. And in the automobile industry, such a large scale multiplex wiring system having high reliability is very innovative in our opinion and will surely have a large impact in the future.

Toyota has been introducing several hybrid vehicles (HV) as a countermeasure to concerns related to the automotive mobility like CO2 reduction, energy security, and emission reduction in urban areas. A next step towards an even more effective solution for these concerns is a plug-in hybrid vehicle (PHV). This vehicle combines the advantages of electric vehicles (EV), which can use clean electric energy, and HV with it's high environmental potential and user-friendliness comparable to conventional vehicles such as a long cruising range. This paper describes a newly developed plug-in hybrid system and its vehicle performance. This system uses a Li-ion battery with high energy density and has an EV-range within usual trip length without sacrificing cabin space. The vehicle achieves a CO2 emission of 59g/km and meets the most stringent emission regulations in the world. The new PHV is a forerunner of the large-scale mass production PHV which will be introduced in a year.

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 camshaft for an automobile engine is generally made of chilled cast iron. But, because of increased demand for higher performance engines, a camshaft with many camshaft has been expected. The cam intervals were necessarily narrow. So it was difficult to manufacture the conventional chilled cast iron camshaft at a moderate price. In the case of a rocker-arm type valve mechanism, higher wear resistance was necessary. After due consideration to solve these problems, development of surface remelted chilled layer camshafts by Toyota's unique manufacturing method has been accomplished. In 1984 Toyota Motor Corporation started the mass-production of this camshaft, first for the new 1.0 liter 1E engine, and then for the 1.3 liter 2E engine. In this paper, the excellent wear resistance, the low manufacturing cost and the characteristic manufacturing method are described.

For the first time ever, a new hybrid system using a 42-V power supply system has been developed for better fuel economy, lower emissions and urban environment. This paper introduces the system configuration, features and gives actual vehicle evaluation results. This system has a motor generator (hereinafter abbreviated as M/G) connected to the engine crankshaft via a belt, in place of the alternator on a conventional vehicle. The electronic control of the M/G has five functions, 1 restarting the stopped engine, 2 driving the vehicle when starting, 3 driving auxiliaries when the engine is stopped, 4 power generation during ordinary traveling and 5 regenerative braking on deceleration braking. By restarting the engine via a belt with motor driving control, a smooth starting without discomfort is achieved. Furthermore, using this motor to drive auxiliaries during idle increases the number of idle stop opportunities.

The use of ceramic insulation to reduce engine heat loss and thus improve fuel economy was examined but found to be detrimental rather than advantageous. This paper analyzes the reasons and presents an alternative approach, namely minimizing the heat transfer area. Experiments were conducted to determine the effects of surface smoothness on BSFC, output torque, heat release rate and piston temperature. It was found that with a mirror-finished combustion chamber, heat loss is decreased and consequently engine output is raised, while fuel consumption is lowered. The percentage reduction in heat loss was ascertained by numerically simulating combustion and was confirmed by FEM analysis of piston thermal distribution.

Engine friction reduction is an effective means to improve fuel consumption. Fluid friction reduction of main bearing is examined for engine friction reduction in cold condition. As one of the examinations, it was focused on low temperature of lubricating oil in the early stage during engine cold start. In hydrodynamic lubrication, the oil film temperature is maintained by balance between heat generation and heat transfer. The heat generation is generated by shear of lubricating oil. The factors of the heat transfer, the following elements are considered as follows, A) The heat transfer to a crank shaft, B) The heat transfer to a bearing, C) The heat transfer by convection. If the heat generation is constant, oil film temperature is increased by reduction of heat transfer. It is considered that the reduction of oil leakage and reduction of the heat transfer by convection is equivalent.

Multi-cylinder hydrogen-absorbing alloy tanks for fuel cell vehicles have 10 to 40 metallic cylinders that are bundled and filled with hydrogen-absorbing alloy. In this system, the cylinders themselves act as a heat exchanger and the working pressure is lowered to 10 to 20 MPa compared with high-pressure MH tanks. Moreover, both heat conduction and mass reduction can be achieved by reducing the wall thickness of the cylinders. A model verification experiment was conducted using a one-quarter-scale prototype of a full size tank, and a conduction simulation model verified in the experiment was used to predict the performance of the full size tank. Results showed that it is possible to fill the tank with hydrogen to 80% of its capacity in a five-minute filling time, although issues related to heat conductivity performance require improvement. Accordingly, it may be possible to adopt this tank as part of a system if the storage amount of the hydrogen-absorbing alloy can be increased.

The authors developed a high-reliability low-cost gold-plated connector for automobiles. The connector is covered with three plated layers, nickel, palladium-nickel alloy, and gold. The three-layer plating helps to reduce the required thickness of gold. This paper describes the reasons why palladium-nickel plating was adopted and compares the corrosion resistance, oxidation resistance and wear resistance of three-layer-plated materials with those of conventional gold-plated materials. In addition, the characterisitics of three-layer-plated connectors were compared with those of conventional gold-plated connectors. It was found that the reliability of three-layer-plated connectors was as high as that of conventional gold-plated connectors.

On the basis of the investigation of the airflow and temperature distributions between the car underside and the wind tunnel floor, methods to improve, the differential gear lubricant cooling performance in high speed running have been studied. It has been clarified that the differential gear lubricant temperature is nearly dominated by the convective heat transfer coefficient and the air temperature around the differential gear carrier. Control of the heat transfer coefficient and the air temperature around the differential gear carrier through the modification of the car underside configuration was found to be the most efficient method to decrease the temperature of the differential gear lubricant.

Engine starting vibration of hybrid vehicle with Toyota hybrid system has variations even in the same vehicle, and a large vibration that occurs rarely may cause stress to the passengers. The contribution analysis based on the vibration theory and statistical analysis has been done, but the primary factor of the rare large vibration has not been clarified because the number of factors is enormous. From this background, we apply machine learning that can reproduce multivariate and complicated relationships to analysis of variation factors of engine starting vibration. Variations in magnitude of the exciting force such as motor torque for starting the engine and in-cylinder pressure of the engine and timing of these forces are considered as factors of the variations. In addition, there are also nonlinear factors such as backlash of gears as a factor of variations.