Coolant circuit for a motor vehicle air conditioning system, using carbon dioxide as the coolant, sets the pressure difference between the inflow and outflow pressures at the second evaporator valve to reduce noise emissions

摘要

The cooling circuit for a motor vehicle air conditioning system, using carbon dioxide as the coolant, has a compressor (1) for coolant compression and a cooler (2) with two pressure reduction units (4,5) each linked to an evaporator (8,9). On starting and stopping the pressure difference between the mean inflow and outflow pressures at the magnetic valve (7) at the second evaporator or the magnetic valve downstream of it is set lower than the pressure difference at the first evaporator during normal running by opening or closing the magnetic valve. The carbon dioxide is held at a critical pressure or higher.