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In respect to the present large refrigerator trucks, sub-engine type is the main product, but the basic structure does not change greatly since the introduction for around 50 years. A sub-engine type uses an industrial engine to drive the compressor, and the environmental correspondence such as the fuel consumption, the emission is late remarkably. In addition, most of trucks carry the truck equipment including the refrigerator which consumes fuel about 20% of whole vehicle. Focusing on this point, the following are the reports about the system development plan for fuel consumption reduction of the large size refrigerator truck. New concept is to utilize electrical power from HV system to power the electric-driven refrigerator. We have developed a fully electric-driven refrigerator system, which uses regenerated energy that is dedicated for our refrigerator system.

Alternator, which supplies electric energy to a battery and electrical loads when it is rotated by engine via belt, is one of key components to improve vehicle fuel efficiency. We have reduced rectification loss from AC to DC with a MOSFET instead of a rectifier diode. It is important to turn on the MOSFET and off during a rectification period, called synchronous control, to avoid a current flow in the reverse direction from the battery. We turn it off so as to remain a certain conduction period through a body diode of the MOSFET before the rectification end. It is controlled by making a feedback process to coincide with an internal target conduction period based on the rotational speed of the alternator. We reduced a voltage surge risk at turn-off by changing the feedback gain depending on the sign of the time difference between the measured period and the target.

We propose a verification method in the field of automotive control systems integrating the concepts of Formal Methods with testing, aiming at efficient and reliable software development. Although Formal Methods are believed to provide the benefits of their rigorous nature and their inherent capability of automation, only limited cases are known where Formal Methods were applied in system and software development, in practice, due to two major difficulties: appropriate abstraction in modeling and scalability in automated reasoning. Focusing on testing on the other hand, there is the difficulty of selecting reasonable set of tests for given verification objectives. In order to overcome these difficulties, our approach is to present verification criteria for testing to appropriately cover the property with the help of the Formal Method concepts.

In this paper, we propose a high voltage brushless AC starter that contributes to improved fuel efficiency and a reduction in the cost of the one-motor two-clutch hybrid system, which we call a 1MG2CL system. We have named it the HV starter, and it is composed of an AC motor, inverter and pinion with a shift mechanism. One of the issues with the 1MG2CL system is the high electrical energy when starting an ICE as it switches over from EV drive to HEV drive. While the ICE is starting, the main motor has to crank the ICE via the clutch; the clutch slips to absorb the main motor power, so the main motor has to output a high power to overcome the loss. Therefore, to contribute to reducing the electrical power by eliminating clutch slip losses, we developed an HV starter as a dedicated ICE starting device. Thanks to the reduction in electrical power, the HV starter is able to improve fuel efficiency and reduce system costs.

Shift selection devices are desired to be flexible for design and layout, in order to realize the next generation of cockpits for Lexus vehicles. In addition, refined shift operation feelings are also required to be suitable for Lexus vehicles. To meet these demands, the Lexus LC500 has been equipped with a shift-by-wire system, which replaces the mechanical linkage between the shift selector and transmission with electrical signals and an actuator. This shift-by-wire system will be installed in a wide variety of Lexus powertrain lineup, including conventional gas vehicles and hybrid vehicles. Therefore, the next generation shift-by-wire system for Lexus has been developed with high reliability and applicability. This technology will be essential when autonomous driving and autonomous parking systems are realized in the near future.

Trivalent chromium passivation is used after zinc plating for enhancing corrosion resistance of parts. In the passivating process, the amount of dissolved metal ions (for example zinc and iron) in the passivation solution increases the longer the solution is used. This results in a reduced corrosion resistance at elevated temperatures. Adding a top coat after this process improves the corrosion resistance but has an increased cost. To combat this, we strove to clarify the mechanism of decreased corrosion resistance and to develop a trivalent chromium passivation with a higher corrosion resistance at elevated temperatures. At first, we found that in parts produced from an older solution, the passivation layer has cracks which are not seen in parts from a fresh/new solution. These cracks grow when heated at temperatures over 120 degrees Celsius.

In automobiles, Integrated Starter Generators (ISGs) are important components since they ensure significant fuel economy improvements. With motors that operate at high voltage such as ISGs, it is important to accurately know partial discharge inception voltages (PDIVs) for the assured insulation reliability of the motors. However, the PDIVs vary due to various factors including the environment (temperature, atmospheric pressure and humidity), materials (water absorption and degradation) and voltage waveforms. Consequently, it is not easy either empirically or analytically to ascertain the PDIVs in a complex environment (involving, for example, high temperature, low atmospheric pressure and high humidity) in which many factors vary simultaneously, as with invehicle environments. As a well-known method, PDIVs can be analyzed in terms of two voltage values, which are the breakdown voltage of the air (called “Paschen curve”) and the shared voltage of the air layer.

Reducing the loss of the power control unit (PCU) in a hybrid vehicle (HV) is an important part of improving HV fuel efficiency. Furthermore the loss of power devices (insulated gate bipolar transistors (IGBTs) and diodes) used in the PCU must be reduced since this amounts to approximately 20% of the total electrical loss in an HV. One of the issues for reducing loss is the trade-off relationship with reducing voltage surge. To restrict voltage surge, it is necessary to slow down the switching speed of the IGBT. In contrast, the loss reduction requires the high speed switching. One widely known method to improve this trade-off relationship is to increase the gate voltage in two stages. However, accurate and high-speed operation of the IGBT gate control circuit is difficult to accomplish. This research clarifies a better condition of the two-stage control and designed a circuit that improves this trade-off relationship by increasing the speed of feedback control.

Due to the recent trend emphasizing on environmental friendly, engine supercharger downsizing technology has been under development globally. In this report, the technical knowledge for high performance and high quality water-cooled CAC development is provided. For higher cooling performance, the optimum fin and tube core matrix water-cooled CAC, delivering best performance and quality have been developed. For higher reliability against thermal stress, the detail specifications of water-cooled CAC based on the transient analysis and the simulation technology have been established.

Toyota Motor Corporation has developed the new compact-class hybrid vehicle (HV). This vehicle incorporates a new hybrid system for the improvement of fuel efficiency. For this system, a new Power Control Unit (PCU) is developed. The feature of the PCU is downsizing, lightweight, and high efficiency. In expectation of rapid popularization of HV, the aptitude for mass production is also improved. The PCU, which plays an important role in the new system, is our main focus in this paper. Its development is described.

The growing functionality and complexity of recent vehicle electronic systems have made inter-device communication (on-board LAN) technology vital to vehicle design. By field of application, the LAN (Local Area Network) systems currently in use are LIN (Local Interconnect Network) used for body systems, CAN (Controller Area Network) used for control systems, and MOST (Media Oriented Systems Transport ) used for multimedia and camera systems, and work to standardize the next-generation communication technology for each of those fields is underway. This paper provides a technical overview of the CXPI (Clock Extension Peripheral Interface) communication protocol, which satisfies the body system requirements (rapid response, system extensibility, high reliability, and low cost). It also presents the progress made on standardization at SAE and other organizations.

A new development environment is required where conflict between control systems is minimized, where processing can be executed while maintaining independence between systems, and where quality can be assured easily. This environment must enable flexibility in software layouts to accommodate software changes during the development process and the parallel development of multiple derivative systems. We have developed virtualization technology (virtual CPU), which allows the execution of system control with a single CPU without conflict between systems. An outstanding virtual CPU architecture that we have developed allows us to execute multiple real-time control tasks with the hardware scheduler, and we have developed hardware that extends the management of address space and interrupt handling, making it possible for a single CPU to be configured as multiple CPUs. Also, we have implemented a bus system that reduces interference between threads.

This paper describes the reliability of silicon carbide (SiC) MOSFET. We clarified the relation between the lifetime of the gate oxide and the crystal defects. We fabricated MOS diodes using thermal oxidation and measured their lifetimes by TDDB (Time Dependent Dielectric Breakdown) measurement. The wear-out lifetime is sufficient for hybrid vehicle but many MOS diodes broke in shorter time. The breakdown points were defined by Photo-emission method. Finally, we classified the defects by TEM (Transmission Electron Microscopy). A TSD (Threading Screw Dislocation) plays the most important role in the lifetime degradation of the gate oxide. The lifetime of the gate oxide area, in which a TSD is included, is shorter by two orders of magnitude than a wear-out breakdown. The mechanism by which threading dislocations degrade the gate oxide lifetime was not discovered. To explain the degradation, we assumed two models, the shape effect and the oxide quality degradation.

A new exhaust emission control system has been developed which complies with the world's most severe emission standard: CARB PZEV. Leaner combustion in cold condition was enabled and rapid warm-up of a close-coupled catalyst was realized by utilizing a newly developed Intake Air Control Valve (IACV) system and hyper-atomization fuel injector. In addition, the newly developed HC adsorbing type 3-way catalyst realized cold HC reduction at lower cost. For further reduction of the exhaust emission, the Variable Valve Timing-Intelligent (VVT-i) system was positively operated immediately after the cold start. By the suitable operation of Variable Valve Timing (VVT), the blow-back from the cylinder enhanced the fuel atomization and re-burning of remaining unburned hydrocarbons (HCs), and increased in-cylinder residual gas reduces NOx.

In recent years, the powertrain system is becoming bigger and more sophisticated than ever, and it is very important that new powertrain systems shall be timely developed just when the market required. In this kind of new system, the quality in particular will be an important factor on the vehicle evaluation issue. With this objective in mind, DENSO has been working on the following challenges, such as the development of key technology, the improvement of quality assurance system, and engineer education to realize them. This reports a general idea on these quality management activities.