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Recently, an increasing demand for comfort has been accelerating the trend toward multifunctional car air conditioners, including zone air conditioning which controls the cabin temperature independently for the driver and the passenger and compensates for the side solar radiation. In addition, the multifunctional air conditioner should be compact to save cabin space and ensure passenger comfort. This report describes the development of a compact and multifunctional car air conditioning unit.

The electricity stored in the battery is the only source of energy driving an electric vehicle (EV). Therefore, the target of the air conditioning system for EVs is to cool and heat the air in the cabin and demist the wind shield using a small power consumption. We have developed a dehumidifying heat pump system that consists of an interior unit constructed to separate the recirculation air flow and fresh air flow, an exterior unit capable of controlling the absorption and radiation of heat, and an inverter-controlled, electric-driven compressor. The results of an experiment using this system proved that it could provide comfortable cabin air and good visibility through the wind shield with small power consumption at ambient temperatures ranging from -10°C to 40°C.

To improve vihicle compartment comfort, there has been a great demand for the development of odor filters which reduce odors, especially external diesel exhaust odors. Therefore, in efficiently developing cabin air filter combining dust removal and deodorant functin, a quantitative formula which enables acquisition of the correlation between sensory evaluation values and instrumental analysis values of odors has been designed and verified. We developed a deodorizing filter that effectively deodorized with minimal use of deodorant, combined with a dust filter based on these figures, to develop a high-performance air conditioning cabin air filter.

In the diesel engine field, increasingly strict emission regulations and customer requirements have necessitated advanced technology. One important subject for diesel engines is cold startability and white smoke under cold conditions. In this paper, the combustion mechanism of a multi cylinder engine under cold conditions is discussed. First, during a starting condition, it is proved that the cold flame, which is caused by previously misfired fuel during intermittent combustion, promotes good combustion on the following cycle. Secondly, following engine starting, it is estimated that there is minimum fuel quantity above which combustion is carried out. The minimum fuel quantity depends upon the temperature of the combustion chamber. Unbalance between the minimum fuel quantity and actual injection quantity results in white smoke emission.

Environmental control of the passenger compartment has become increasingly important and sophisticated. One major consideration of interior comfort is clean, healthful, aromatic air. Accordingly, two new products were developed to increase the dust removing and deodorizing effects. These are the “Air Purifier” and the air conditioner ventilation filter called the “Air Refiner”. The Air Purifier affects the air inside the vehicle, and the Air Refiner affects the air from outside the vehicle. Remarkable effects are achieved by employing a newly developed material called “Impregnated Activated Carbon Fiber (IACF)” which is utilized in both the Air Purifier and the Air Refiner. In addition to the air purification system, a new fragrance control system called the “Aroma Controller” was developed. The Aroma Controller allows the user to select from three aromatic fragrances. The fragrance is emitted intermittently by way of “1/f fluctuation control” via microcomputer control.

As an alternative refrigerant for CFC-12, HFC-134a is the best choice in automotive air conditioning system. Refrigeration cycle characteristics using HFC-134a have been previously reported, but most of those papers were confined to the differences of basic system performance between CFC-12 and HFC-134a. So this paper emphasized the analysis on functional components. As a result, we have introduced the differences of refrigeration cycle characteristics which had not been acquainted well by now.

Extensive work was conducted to develop a corrosion resistant brazing sheet alloy and to apply it to a drawn cup type evaporator in automotive air conditioning system. The items to be investigated included the influence of chemical composition of the core alloy on corrosion resistance, suppression of erosion during the brazing cycle, and enhancement of the brazing sheet formability. Additional investigation was conducted to develop a new corrosion test method on the basis of better understanding of the mechanism of corrosion in the field and to evaluate the corrosion resistance of a evaporator fabricated from the new alloy. This paper, as Part 1, describes the results of alloy development from the metallurgical and electrochemical point of view.

Instrument clusters used in automobiles play an important role as man-machine interface. A variety of information about the current driving situation is conveyed to the driver quickly and accurately. A great interest has been taken in the high visibility and legibility of the head-up display (subsequently abbreviated as HUD). Originally developed as display used in aeronautical applications, we have tried to exploit ways to adapt this device for automotive use. We have succeeded to produce a new HUD system, which has the following design features; (1) High brightness and high contrast display device using a liquid crystal display (subsequently abbreviated as LCD) and a halogen lamp illumination. (2) Long focus display in two colors using holographic lens. (3) Automatic dimming control system using an illuminance sensor. (see Fig. 1)

The purpose of this study is to present a new method for controlling a car air conditioning system, in which the air temperature can be controlled to produce any level of occupants' thermal sensation by utilizing car occupants' skin temperatures as a controlling index. In this paper, an equation for a quantitative evaluation of car occupants' thermal sensation, in steady and non-steady states, by face skin temperature and its rate of change was developed and was confirmed by experiments in an environmental chamber to be applicable for all seasons with an accuracy of ±1 in the thermal sensation voting scale we used.

The effect of the amount of refrigerant on automotive air conditioning system behavior was clarified through simulations and experiments. It has been revealed that the best way to measure the amount of refrigerant in an air-conditioning system is to measure the liquid-gas flow ratio in the liquid line. In order to measure the liquid-gas flow ratio, a mechanical sensor for fluids was developed and applied to a refrigerant monitoring system which can identify when the amount of refrigerant drops to 60% of the regular level.

The authors developed a low-speed in-vehicle network for the body control system on passenger cars, where the most remarkable effects to reduce the number of wire harnesses could be expected. First, the authors analyzed the body control system to clarify the specifications required to build a low-speed in-vehicle network. Then the authors worked out optimum communication protocol, placing emphasis on cost reduction which is the key to expanding the applications of the low-speed in-vehicle network over wider fields. The low-speed in-vehicle network was evaluated for its performance through simulation and on-vehicle tests, and proved the practical validity of the concept. It was also verified that introducing the low-speed in-vehicle network has a satisfactory effect to reduce the number of wire harnesses.

1 Attenuation of acoustic noise from automobile components is important for passenger comfort. Since the alternator is one of the major sources of noise, many manufacturers have studied the various mechanisms which generate noise within an alternator as well as the methods to reduce the noise level. This paper presents the dynamic properties of the alternator with respect to the acoustic noise during current generation, and introduces a vibration damping structure based on experimental modal analysis. Rotating magnetic forces in a magnetic circuit (stator and rotor) can excite numerous structural resonances, resulting in acoustic noise. A modal analysis performed on the major magnetic circuit of the alternator (Nippondenso Co., Ltd.) revealed that the stator has elliptic, triangular and rectangular mode shapes in the radial coordinate plane, while the rotor does not have any significant resonances in the same 0 - 3 kHz region.

A method of real time oil concentration measurment has been developed utilizing the effect of ultraviolet light absorption by lubricating oil in the liquid refrigerant line of an automotive air conditioning system. The light wavelengths from 200nm to 370nm are selected based on the ultraviolet light absorption sensitivity of the oils and refrigerants (CFC12,HFC134a). The effects of temperature,pressure and contaminantion on the absorbance of light are investigated in order to determine how these parameters affect the concentration measurement. The density changes of refrigerants are then compensated in the calculation for the oil concentration. The uncertainties of the overall concentration measurement are less than ±0.1 weight percent at 1 weight percent concentration. A transient oil circulation of the automotive air conditioner is measured by using this method.

Semi-active suspension is one of many effective devices to improve vehicle stability, controllability and riding comfort. A practical means to realize semi-active suspension is to vary the damping force of the shock absorber. In this paper, we propose a new type of shock absorber using a piezoelectric sensor and actuator. The piezoelectric sensor and actuator are built into the piston rod which is a part of the shock absorber. The piezoelectric element provides a fast response and a high actuation force. We used the piezoelectric element in shock absorbers in order to take advantage of these two features. High level compatibility between stability, controllability and riding comfort is expected, since damping force changes very quickly using this new type of shock absorber. In this paper, several topics are discussed. First, a general description of the damping force control system with simple configuration is explained.

We have developed a highly corrosion-resistant serpentine type condenser which is characterized by its manufacturing process that zinc is coated on the surface of a multi-cavity extruded tubing at the rate of 5-20 g/m2 by arc spray, and then, thus prepared tubing and corrugated fin stocks are brazed by the conventional Nocolok brazing process (Herein after this is referred to as ZAS NB process). By this brazing process as well as conventional flux brazing (FB) process, a highly pitting corrosion-resistant zinc diffusion layer is formed on the surface of the tubing at the time when brazing is operating. This newly developed method achieved improvements in productivity and quality of product.

This paper introduces a new type of radiator that has been developed with the objective being, high performance (compact size), light weight, and high quality in the field of copper/brass radiators that are superior in heat conduction, lower in price, yet there is still more room for improvement. The development of a new copper/brass radiator with the objective being higher performance (more compact), lighter weight, and higher quality has been completed. The synthetic study covered is not only an in-depth analysis of performance and structure, but the new development of materials and production engineering. As a result, the new radiator has a minimum of 10% increased performance, a minimum of 25% weight reduction, and its corrosion resistance is more than twice that of a conventional radiator.

The smaller and lighter SV-06 sliding vane type compressor has been developed as the successor of the swash plate type 10P08 compressor for mini-car air conditioning applications. The SV-06 is the first vane type compressor in the world which utilizes an aluminum cylinder and rotor to achieve weight reduction. This was accomplished by introducing several new features to the design, such as a boron treated vane and smooth cylinder profile. Thinner vanes and a high performance oil separator were also introduced for compactness. This paper presents the many design features that allow small size and low weight while maintaining compressor performance and reliability, and focuses on the most important technology: (1) Abrasion Characteristics of Boron Treated Vane Against Al-Si Alloy (2) Oil Separator Performance

This paper is an introduction to the design, development and heat transfer performance of a new drawn-cup plate evaporator for the refrigerant cycle of automotive air conditioning systems. This evaporator is characterized by the tank section at one side alone and U-turn refrigerant path in each tube. This system has reduced dead space and has superior overall heat transfer coefficient. Therefore, we expected that its potential performance would be much higher than any other conventional type. But, while developing it, we encountered some serious structural problems which affected the flow of the refrigerant and heat transfer in the U-turn sections. We isolated the causes of the performance degradation by analizing the refrigerant flow behavior in these sections. With this type of evaporator we finally achieved our target of 15% improved performance compared with the serpentine tube evaporator.

This paper describes the development of the two-dimensional semiconductor device simulator called DS2* and its application in automotive power MOSFET design. DS2 clarifies carrier motions in MOSFETs under various operating conditions and calculates the current characteristics in intense electric fields in order to evaluate the device breakdown. Simulation results with p channel power MOSFETs for automotive application indicate that on resistance is significantly dependent on device miniaturization and that device breakdown is caused by one of three mechanisms which are, avalanche from the surface layer, reach through arid punch through.

EMI suppresion capacitors and filters are common in automobile electronics today, but they are insufficient for heavy concentrations of wideband electromagnetic radiation. To resolve this problem, a highly-integrated Ceramic Absorber was developed to efficiently shield against frequencies from 1MHz to 1000MHz, which is mountable on the control circuit board easily, as it is the form of a flat plate strip line. This filter provides the signal line with an electromagnetic absorption effect through line transmission characteristics. Research into ceramic materials was required to determine the specific dielectric constants and frequency characteristics of ferroelectric ceramic materials. The development objective was material with optimum dielectric dispersion, as determined from research into energy absorption based on the Debye dielectric dispersion theory.