Search Results

Regarding the prevention of global warming and ozone layer depletion to protect the global environment, energy conservation and disuse of CFCs are among the recent industrial requirements. An ejector cycle can save power by eliminating expansion energy loss in the conventional vapor compression refrigeration cycle, which uses an expansion valve, and using the otherwise lost energy as compressor power. This technology is useful for almost all kinds of refrigerating and air-conditioning systems, but has not yet been developed to a practical level anywhere in the world. We have developed a practical ejector cycle technology and successfully commercialized it for the first time in the world, as an ejector cycle refrigerator that drastically improves refrigerating capacity and power efficiency while substantially reducing system weight, in comparison with refrigerators using the conventional vapor compression cycle.

Among aluminum heat exchangers used for automotive air conditioning, the evaporator is located in the instrument panel. We have developed a new evaporator by: 1) improving the heat transfer performance through use of thinner tubes and fins; 2) establishing technologies for improving corrosion resistance and enabling reduction in wall thickness (development of highly corrosion-resistant material and control of Zn diffusion by shortening brazing time); and 3) improving refrigerant distribution in the tanks. The new evaporator is equivalent to our conventional MS Evaporator (of Multi-Tank Super-Slim Structure)(1) in cooling performance and corrosion resistance, while being significantly thinner (35% reduction) and lighter in weight (40% reduction).

In today's motorized society, various automotive technologies continue to evolve every day. Amid this trend, a new concept with respect to automatic transaxle gear-shifting has been developed. In order to materialize a new concept for shifting operation with a universal design in mind, a system has been developed: a shift-by-wire system developed specifically for hybrid vehicles. The greatest advantage of this new system is the lack of constraints associated with the conventional mechanical linkage to the transaxle. This allows freedom of design for the gear selection module. A revolutionary improvement in the ease of shifting has been realized by taking full advantage of this design freedom. In addition, this system contributes to an innovative design. For improved ease of operation, the operation force of the shift lever of this system has been dramatically reduced. For parking, the driver can engage the parking mechanism of the transaxle at the touch of a switch.

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.

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.

A new after-treatment system called DPNR (Diesel Particulate-NOx Reduction System) has been developed for simultaneous and continuous reduction of particulate matter (PM) and nitrogen oxides (NOx) in diesel exhaust gas. This system consists of both a new catalytic technology and a new diesel combustion technology which enables rich operating conditions in diesel engines. The catalytic converter for the DPNR has a newly developed porous ceramic structure coated with a NOx storage reduction catalyst. A fresh DPNR catalyst reduced more than 80 % of both PM and NOx. This paper describes the concept and performance of the system in detail. Especially, the details of the PM oxidation mechanism in DPNR are described.

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.

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.

“Adherent odors” emitted from the evaporator in an air-conditioning (A/C) unit are caused by desorption of adherent odorant on the evaporator such as exhaust gas, cigarette odor, interior materials and so on. In an attempt to reduce adherent odors we have developed and initiated production of the ‘Adherent Odor Reductive Coating’. In this paper we investigate the adherent and desorption mechanisms of these odors by componential analyses and odor sensory tests. As the result of the investigation, we find that the odor emission relates to hydrophilic group on the evaporator surface and we design evaporator coating based on the result. This paper also reports the positive effects that our ‘Adherent Odor Reductive Coating’ has in reducing adherent odors.

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.

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.

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.

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.

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.

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.

As a result of recent improvements in engine efficiency, vehicle heating performance has decreased and the demand for auxiliary heat sources is increasing. To help meet this need, we have developed an auxiliary heat system known as the “Hot Gas Heater”. The Hot Gas Heater uses components common to the vehicle air-conditioning system that are not used during winter. However, there are some concerns with this system. In this paper we describe our solutions to these problems. We reduced gas flow noise through multi-stage pressure reduction, and prevented fogging by adding “water retention memory” and “evaporator outlet air temperature control” functions to the system. As a further benefit, we developed a New Accumulator Cycle that moves the cooling cycle accumulator tank to the high-pressure side.

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.

Phosphating is a surface treatment process widely used for preparing metal surfaces before painting. The phosphate coating plays a very important role in enhancing after-painting corrosion resistance, which is one of the essential quality requirements of painted surfaces. Continued research and development is therefore under way in various parts of the world to increase the corrosion resistance enhancement effect of phosphating. Moreover, because the demand for environmental protection has been increasing in recent years, reducing the amount of waste (sludge) generated during the phosphating process is also strongly required. To meet these requirements, we have developed a novel phosphating technology called the “electrolytic phosphating process,” which drastically enhances corrosion resistance after painting and reduces sludge generation. The developed process has already been put to practical use for surface preparation before cation electrodeposition painting of automotive parts.

As a means to reduce exhaust emission, narrowing nozzle hole diameter is known to be an effective method of improving fuel atomization. In general, Electrical Discharge Machining (EDM) is more effective than other machining techniques because there is no burring and no machining force is apply to the tool, but the drawback to EDM is a low removal rate. An EDM drilling device by using piezoelectric elements has been newly developed. This device can drive a wire electrode at a high response of 5kHz. As a result of high response, this device can drill holes 0.1-0.5mm in diameter 3 times more efficiently than a conventional electrical discharge machine.

This paper introduces the cruise control system with distance control function, that is called Adaptive Cruise Control (ACC), that uses a scanning laser radar as a sensor to detect preceding vehicles. With the goal of increasing the driving convenience and comfort when compared to the conventional cruise control, lots of ACC systems have been proposed and developed. This paper presents ACC system using the scanning laser radar which was developed by Toyota, and describes the adaptation of the system specifications. This ACC system was able to greatly reduce the driver's work load, and increased the driver's convenience and comfort when operating the cruise controls system. In addition, we were able to design this system to be highly dependable and inexpensive and supply it to the market as a result of incorporating various ideas for improvements.