A Compact Horizontal Scroll Type Compressor for Room Air Conditioners

This paper presents the construcrion, newly developed design technologies and performance characteristics of a compact horizontal scroll-type compressor for room air conditione~:s. The authors were able lo develop a compacl variable speed horizontal scroll-type compressor with a cooling capacity of I. 8 kW, which necessitated the development of new mechanisms, namely, an alCial compliance mechanism for compensating liquid compression, an oil pump mechanism for Iubricalion and a suppression mechanism for oil discharge. Use of the new compressor in room air conditioners made it possible to reduce rhe elCternal unil of the air conditioner by about 25%. The new compressor possesses a high efficiency: about I 0% higher especially al low speed operation. !.INTRODUCTION In recent years, in the field of room air conditioners, I here has been an increasing demand for reduced equipment energy consumption as well as for lower vibration and noise. The attention of the authors was drawn to the outstanding low vibration and low noise characteristics of scroll compressors, and the authors have already developed the world's first compact vertical scroll compressor with a cooling capacity of 2.4 kW, which is used in room air conditioners that were put on the market in 1990. This paper describes efforts to develop a smaller horizontal scroll compressor, with the goal of reducing the size of lhe external unit of split-type room air conditioners. The cooling capacity of the new compressor is 1. 8 kW, which is the most frequently used capacity for household applications in Japan. Because horizontal compressors have up to now presented problems such as difficulty in supplying lubricating oil to the mechanisms and discharging large amounts of oil from the compressor to the refrigeration cycle, achieving this goal was considered difficult. However, by developing a new trochoid-type oil pump mechanism for lubrication and a suppression mechanism for oil discharge, completely horizontal installation was made possible. In addition, by using a radial compliance device developed by our company, high efficiency was assured when the cooling capacity· was reduced. Furthermore, greater reliability was achieved by developing and adopting an uial compliance device that limits the effects of liquid compression. In this paper, the structure of the newly developed scroll compressor, as well as its features and performance characterisrics, are presented. 2. OVERVIEW OF THE NEWLY DEVELOPED SCROLL COMPRESSOR The design of the newly developed scroll compressor is shown in Figure I, and its specifications are given in Table 1. 2.1 Internal High-Pressure Structure gf the Shell In development, emphasis was placed on compression efficiency, and rhus a highpressure shell was adopted with the aim of minimizing the degree of superheat of the intake gas and suppressing the amount of oil discharged from the discharge conduit.