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We have developed Li-ion battery heating system which is direct resistance heating for hybrid electric vehicles (HEV), plug-in hybrid vehicles (PHEV) and electric vehicles (EV) by use of an inverter and a motor. One relay is added between a positive terminal of Li-ion battery and one-phase (e.g. U-phase) of a three-phase motor. When additional relay is turned on, the motor coils, IGBTs (Insulated-gate bipolar transistor) and diodes in the inverter and a smoothing capacitor for the inverter constitute buck-boost DC to DC converter. IGBTs are controlled to repeat charging and discharging between the battery and the smoothing capacitor. We made a system prototype and examined battery heating capability. And also we optimized charging and discharging frequency from impedance and current to improve heat generation. This method can increase battery temperature from −20 degrees C to 0 degrees C in 5 minutes and can extend EV driving range.

Recently, enhancements to product quality from the standpoint of consumer protection have become a prerequisite in responding to the increase of social awareness of product quality. The results of our researches[1, 2] on quality problems suggest that they were often induced by a known contributing factor, which means many of them could have been prevented if the design engineers and/or design reviewers had “smelled” the known factors. This report describes the steps taken by the System Control Components Product Division in DENSO Corporation in order to make a change to the existing quality control strategy by providing a new systematic tool for conveying know-how needed to prevent recurrences of quality problems.

In recent years, background noise in vehicle interiors has tended to decrease more and more in hybrid and luxury cars. As a result, there is an increased demand for noise reduction capabilities of automotive grease, in addition to the original lubrication function. In this study, we report the mechanism of noise reduction in car air conditioners, and describe a new grease that meets both excellent noise reduction and low temperature performance. In the collision model, sound pressure is generated by collision velocity and material properties (ex. Poisson ratio, Young's modulus). When the grease is applied over the area around the collision point, collision velocity is reduced because of the viscous resistance of the grease. Therefore, it is effective to use highly viscous base oil for noise reduction. However, the base oil also harmfully influences low temperature performance.

To meet the requirements for lower fuel consumption and emissions as well as higher performances, a “Variable Valve Timing - intelligent by Electric motor (VVT-iE)” system has been newly developed. The system has been firstly adopted to the intake valve train of the Toyota's new 4.6 and 5.0 litter V8 SI engine series. The VVT-iE is composed of a cam phasing mechanism connected to the intake camshaft and brushless motor integrated with its intelligent driver. The motor-actuated system is completely free from operating limitation caused from hydraulic conditions. This enjoys an advantage for reducing cold HC. The system also presents further reduction in fuel consumption.

As the whole world has been getting more concerned about the environmental protection, the emission regulations are getting stricter. The requirement to diesel engine is to develop the high-level engine management system to reduce both PM(Particulate Matter)and NOx. For PM reduction, post-treatment technology using a pressure sensor and a diesel particulate filter (hereinafter referred to as DPF) is necessary. This system burns out the clogged PM at the filter that the pressure sensor detects. The pressure sensor used in the DPF system has to be at an affordable price and to be reliable against corrosion, freezing, moisture and clogged soot in the harsh environment of exhaust gas with high humidity where highly-acid condensation water and the produced soot can intrude. This paper describes our newly developed pressure sensor that is suitable for the DPF system. The main features are as follows: a. Semiconductor type sensor with a simple structure and being less costly. b.

Ever since the creation of the spark plug, improvements have continually been made to achieve high ignitability and long life. To fulfill these requirements, “Iridium Spark Plug” was introduced in 1997 with fine-wire center electrode technology to promote ignitability and long life. Then in 2003 “Super Ignition Spark Plug” was developed which uses fine-wire precious metal alloys on both the center and ground electrodes to achieve supreme ignitability and long life. Currently, the global technology trend is focusing more and more on the regulation of emissions and fuel consumption. This is driven by increased awareness for environmental conservation. These regulations are becoming stricter, which leads to a higher demand for spark plug ignitability from all kinds of vehicles ranging from luxury cars through compact sized cars. Particularly in the small vehicle category, both ignitability and low cost are a requirement.

The whirl noise on turbochargers is generated by the self-induced vibration of the oil film in the bearing system. The noise is characterized by its frequency behavior that doesn't increase proportionately to the turbo shaft speed. It tends to be felt annoying. In this paper, to improve the whirl vibration, a statistical analysis approach was applied to the bearing specifications. The results from experiments showed that the bearing clearances played an important role in the reduction of the whirl vibration. To further investigate into this phenomenon, the shaft oscillation behavior was measured. And a vibration simulation program for the turbocharger bearing system was also developed.

Recently many automotive components have become electrified and an ultra high speed drive (over 150,000 rpm) is now expected in applications such as a turbocharger. In these applications, a robust induction motor (IM) with a rectangular wave drive is generally adopted. A speed sensor is required to control the IM, but it can cause problems concerning cost, space and reliability. Thus, a sensorless speed detection method is required. Because general sensorless methods based on a sinusoidal wave drive are not applicable to a rectangular wave drive, we propose a method utilizing slot harmonics that are generated by the mechanical structure of the IM. Signal-to-noise (S/N) ratio of slot harmonics is very small, and hence we suggest three techniques: a detection circuit, a digital filter with a variable passband, and a detection method to restart the motor while rotating.

We have developed a high-precision linear Hall sensor, which can detect absolute angles from 0 to 360°. In this sensor, novel vertical Hall elements have been used that can be fabricated using CMOS process technology, and the signal processing circuit is incorporated on the same chip. Using two vertical Hall elements placed precisely at an angle of 90° in the center of the chip, two-dimensional magnetic signals are detected. These signals are converted to an absolute angle by calculating the arc tangent of two Hall voltages. Moreover, this process compensates for the temperature dependence of these signals. Such a novel integrated vertical Hall sensor is promising for a wide range of applications.

To enhance drivers' convenience and safety, headlamps and headlamp control systems have been remarkably improved. For example, in daytime driving condition, auto-lighting systems support drivers especially when they repeat entering and exiting tunnels in mountain areas. On the other hand, in nighttime driving conditions, the higher luminance headlamp HID gives drivers the enhanced visibility and Adaptive Front-lighting System (AFS) offers them the increased forward visibility on curves. Nevertheless, their performances are not yet enough developed to meet the market demands. In case of entering tunnels, the lighting-up timing is sometimes later than desired. In case of HID and AFS, their potentials are sometimes unnecessarily restrained to prevent glare to oncoming vehicles even they don't exist. These problems should be solved by adding the scene sensor to those systems.

In order to clarify the combustion behavior in the ultra high engine speed range, a new technique has been developed. This technique is composed of ionization current detection and flame observation, and is highly heat-resistant, vibration-resistant, and has a quick response. From analyzing the flame front propagation in the high-speed research engine, it was found that the flame propagated throughout the entire cylinder over almost the same crank angle period irrespective of engine speed introduction.

In order to clarify the diesel fuel spray characteristics inside the cylinder, we developed two novel techniques, which are preparation of same level of temperature and pressure ambient as inside cylinder and quantitative measurement of vapor concentration. The first one utilizes combustion-type constant-volume chamber (inner volume 110cc), which allows 5 MPa and 873K by igniting the pre-mixture (n-pentane and air) with two spark plugs. In the second technique, TMPD vapor concentration is measured by using Laser Induced Exciplex Fluorescence method (LIEF). The concentration is compensated by investigation of the influence of ambient pressure (from 3 to 5 MPa) and temperature (from 550 to 900 K) on TMPD fluorescence intensity. By using two techniques, we investigated the influence of nozzle hole diameter, injection pressure and ambient condition on spray characteristics.

This paper describes the customized power MOSFET technologies that we have developed over the last twenty years for automotive use. During the 1980s we developed thermal-destruction free power MOSFETs with monolithically integrated polysilicon thermal sensing diodes (PTSDs), which are in wide use around the world. In the 1990s, we succeeded in developing the CONCAVE-DMOSFET, the first vertical channel power MOSFET for automotive use that achieves both lower dissipation and optimal gate reliability. Recently, we have greatly advanced power MOSFET performance through the development of PTOx trench-gate MOSFETs (TMOSs), where PTOx stands for partially thick gate oxide film structure. The PTOx structure consists of thick oxide around the trench top, thin oxide on the trench sides, and thick oxide at the trench bottom, and is formed using a simple process that we developed.

Inverter type electric compressors capable of providing cooling capability during engine stop and that do not cause fuel efficiency drop during air conditioning system use are recently being used in hybrid vehicles that have been drawing attention for their low fuel consumption and low emissions. Conventionally, the electric compressor inverter, like other high-voltage devices, was located in a cooling unit known as a power control unit (PCU) box because it requires cooling. However, inverter installation in the PCU box is subject to rigid installation constraints, and there is increasing need to integrate it with the electric compressors. In the present development, we adopted inverter-integrated construction in which the inverter is cooled using suction refrigerant etc., so as to make the electric compressor compact.

In a common rail type fuel injection system installed in recent diesel engines, a supply pump is needed to accumulate high pressure fuel. In this supply pump, a bushing is used for the outer cam system. The bushing is lubricated by diesel fuel with relatively low viscosity and unit load of the bushing is higher. Therefore, lubricating film thickness of the bushing is extremely thin. In order to ensure the bushing function under such severe sliding conditions, the bushing is required higher seizure resistance and higher fatigue resistance. Conventionally, lead bronze alloys are applied for the bushing material. We developed a new high performance copper alloy material without lead, which is one of substances of environmental concern. The newly developed bushing contains bismuth instead of lead for tribological component.

We have been developing the mixed-potential type NOx sensor which can detect the total-NOX concentration directly in exhausts for automobiles. It has been confirmed that the sensor is capable of detecting wide concentrations of total-NOx from 20 to 1000 ppm under the condition from rich-burn (A/F=12) to lean-burn without any interference from reducing gases, such as HC and CO. In addition, it has been confirmed that the sensor output is correlated fairly well to NOx concentrations from the analyzer in the engine test at any rotations. The results obtained here indicate that the present sensor has great possibility of being utilized as an on-board NOx sensor for practical use.

In recent years, new technologies have been developed and are being marketed with the aim of reducing the number of injuries and fatalities due to traffic accidents. They range from systems designed to reduce the driving burden to systems for controlling vehicles in the hope of mitigating the harm done by accidents when they do occur. One of the most important components in creating these systems has been a front obstacle detection sensor that detects obstacles in the paths of vehicles. DENSO is developing laser sensors, millimeter-wave radar, and vision sensors for front obstacle detection. Of these three, it is the laser sensors that have had the important role of supplying adaptive cruise control (ACC) to the market at a low price. This paper focuses on the laser sensor, the expansion of its applications, and the development of new technology to that end.

Through the basic research of the plasma assisted catalyst system using DeNOx catalysts and the gas analysis of the system, its conceptual use for automobile diesel engine applications has been studied. This study has shown that the length between the plasma reactor and the catalyst reactor does not affect the NOx conversion. To obtain an efficient NOx conversion, the plasma should affect both the HC as the reductant and NOx at the same time. In the case of γ-Al2O3 and C3H6, the main component for NOx reduction was CH3CHO generated by the plasma. Under 250 deg. C, the temperature was too low for the γ-Al2O3 to become effective. Therefore, the NOx conversion became low. At 400 deg. C, the NOx conversion became high. However, at 600 deg. C, the CH3CHO for reducing NOx was not generated, and the NOx conversion decreased.

NOx reduction activity in an oxidizing exhaust gas was significantly improved by discharging non-thermal plasma and catalysts (plasma assisted catalysis). We investigated effective catalyst for plasma assisted catalysis in view of hydrocarbon-selective catalytic reduction(HC-SCR). Plasma assist was effective for γ-alumina and alkali or alkaline earth metals loaded zeolite and γ-alumina showed the highest NOx conversion among these catalysts. On the other hand, Plasma assist was not effective for Cu-ZSM-5 and Pt loaded catalyst. The NOx conversion for the plasma assisted γ-alumina decreased by formation of a deposit on the catalyst below 400°C. It is shown that indium loading on γ-alumina improved the NOx reduction activity and suppressed the degradation of the NOx reduction activity at 300°C with plasma assist.

We developed a high performance automotive lithium-ion battery and applied it to our new Toyota Intelligent Idling Stop System. This hybrid power management system has been introduced in the “intelligent package” of Toyota Vitz vehicles sold in Japan. The lithium-ion battery is installed under the seat on the passenger-side. The battery supplies electric power to the auxiliary electrical systems during the “idling stop” mode, and when restarting the engine. The main requirements of this battery are to supply high electric power output even at low temperatures and at the same time, maintain continuous power during charge and discharge cycling, and have long storage life. This performance has been accomplished successfully through a series of improvements in battery materials and structures.