Patent ID: 6786057
Filing Date: 2004-09-07
Classification: F25B

Abstract:
A method for controlling a refrigerant loop in an air-conditioning unit, especially for the passenger compartment of a vehicle, said loop containing a compressor (1) suitable for receiving the refrigerant in the gaseous state and for compressing it, a refrigerant cooler (2) suitable for cooling the refrigerant compressed by the compressor, at approximately constant pressure, by transferring heat to a first medium, an expander (4) suitable for lowering the pressure of the refrigerant leaving the refrigerant cooler by taking it at least partly into the liquid state and an evaporator (5) suitable for making the refrigerant in the liquid state coming from the expander pass into the gaseous state, at approximately constant pressure, by removing heat from a second medium in order to cool the space to be air-conditioned, the refrigerant thus vaporized then being sucked up by the compressor, the loop furthermore containing an internal heat exchanger (3) allowing the refrigerant, flowing in a first path (3-1) of the internal exchanger, between the refrigerant cooler and the expander, to yield heat to the refrigerant flowing in a second path (3-2) of the internal exchanger, between the evaporator and the compressor,wherein in that a first condition likely to reveal the presence of refrigerant in the liquid state in said second path is monitored and the flow rate of refrigerant in the loop is reduced when said first condition is satisfied, and in which said first condition consists in that the efficiency &eegr; of the internal heat exchanger, represented by equation Î·=Tpi-TeoTco-Teo[1]in which Tpi, Teo and Tco are the compressor inlet temperature, the evaporator outlet temperature and the cooler outlet temperature respectively, is less than a reference value &thgr;0.