Automotive A/C System Integrated with Electrically-Controlled Variable Capacity Scroll Compressor and Fuzzy Logic Refrigerant Flow Management 2001-01-0587

This paper describes the recent efforts on developing an automotive climate control system throughout integrating an electrically-controlled variable capacity scroll compressor with a fuzzy logic control-based refrigerant flow management.

Applying electrically-controlled variable capacity compressor technology to climate control systems has a significant impact on improving vehicle fuel economy, achieving higher passenger comfort level, and extending air and refrigerant temperature controllability as well. In this regard, it is very important for automotive climate control engineers to layout a system-level temperature control strategy so that the operation of variable capacity compressor can be optimized through integrating the component control schemes into the system-level temperature control.

Electronically controlled expansion devices have become widely available in automotive air conditioning (A/C) systems for the future vehicle applications^{(1, 2, 3 and 4)}. An electronic expansion valve (EXV), similar to the mechanically actuated thermostatic expansion valve (TXV), is a flow control device whose operational goal is to throttle and regulate the refrigerant flow rate. Principally, TXV regulates the refrigerant entering the evaporating equipment in response to the superheat variation. Comparing to the mechanical actuation mechanism of TXV, the electronically modulated EXV gives the additional flexibility to apply the microprocessor-based intelligent control. Accordingly, a fuzzy logic algorithm of EXV has been incorporated to the A/C system control in order to achieve a high efficiency and optimal operation.

The primary objectives of this paper are to (a) present the design features and control mechanism of an electrically-controlled variable capacity scroll compressor; (b) describe the temperature control system architecture of refrigeration circuit and air flow management; (c) describe the architecture of fuzzy logic control of a refrigerant flow control; and (d) discuss and analyze the results obtained in bench testing.