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The important problems to be tackled from the point of view of preventing global warming are to save the power consumption of car air conditioning systems and reducing the refrigerant used in those systems. Our approach to the task is to enhance system efficiency by utilizing sub-cooling at the outlet of the condenser and also to reduce the amount of refrigerant through a refrigerant behavior pattern analysis. This approach has created a simple system construction using an integrated condenser/receiver device.

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.

Concerns on environmental protection are being intensified throughout the world in recent years. Of those concerns, depletion of the ozone layer in the atomosphere caused by CFC emission into the atomosphere is the target of serious concern as shown in Fig. 1. At present, the use of CFC production is restricted by regulations at the global level, and CFC will be phased out by the end of 1995. In this regard, the authors have developed a new vehicle air conditioner to adapt to a new refrigerant HFC-134a, which is gentle to the ozone layer, and to replace CFC-12. The new refrigerant system was introduced to the market in October, 1991, and the replacement will be almost completed by the end of 1993 for the Lexus and Toyota production vehicles. This paper describes the development of the new compressor lubricant, seal rubber, hose and desiccant by taking into consideration the materials concerned and the number of technological issues involved in the new refrigerant, HFC-134a.

The A/C compressor installed in the Toyota cars on sale in the Japanese market since August 1983, has adopted the variable displacement control method, and as a result, both comfort and power saving have been obtained. The compressor called “Two-stage variable displacement type A/C Compressor (10P-V)” is based upon the swash-plate type compressor, with ten cylinders to the front and rear of the cylinder block, and is constructed with a two mode choice. In the first, high load cooling is carried out (100% displacement) with all the cylinders operating. In the second, low load cooling is carried out (50% displacement) with the five cylinders in front operating while the discharge valves of the five rear cylinders are unloaded.