Air-conditioning system for a motor vehicle

Abstract

In an air-conditioning system for motor vehicles, the radiator for heating the passenger compartment is excluded from connection to the circuit for cooling the engine when heating of the passenger compartment is not required. In this condition, a mixing valve is set in an intermediate position, in which part of the flow of air leaving the evaporator of the system flows directly in the passenger compartment of the motor vehicle, keeping it cooled, while part of the flow of air leaving the evaporator flows through the aforesaid heating radiator, which in this condition functions as accumulator of cold. When the cooling circuit is temporarily deactivated, cooling of the passenger compartment can be ensured by the radiator, that yields the previously accumulated cold.

1 . An air-conditioning system of a motor vehicle, comprising:
 an evaporator for cooling the air, forming part of a cooling circuit, and interposed in a path of a flow of air;   a radiator for heating the air, connected to the circuit of the liquid for cooling the engine and set in the aforesaid path of the flow of air, downstream of the evaporator; and   a mixing valve for directing the flow of air leaving the evaporator all through the heating radiator, or else all directly to the passenger compartment, without passing through the heating radiator, or else part through the cooling radiator and part directly to the passenger compartment,   wherein, in the connection between the heating radiator and the circuit of the liquid for cooling the engine, a by-pass valve is provided that can be activated for excluding the heating radiator from the circuit of the liquid for cooling the engine; and   in that control means are provided, configured for activating said by-pass valve and for keeping the aforesaid mixing valve in an intermediate position when heating of the passenger compartment is not required and the cooling circuit is active so that in said conditions the radiant mass of said heating radiator functions as accumulator of cold, which can be subsequently used for keeping the passenger compartment cooled also during a temporary arrest of the cooling circuit.   
     
     
         2 . The system according to  claim 1 , wherein said control means are electronic control means programmed for keeping said mixing valve in said intermediate position when heating of the passenger compartment is not required and the cooling circuit is active so as to exploit the radiant mass of the heating radiator as accumulator of cold, said electronic control means being instead programmed for displacing the mixing valve into a position in which the entire flow leaving the evaporator is forced to pass through the heating radiator in the conditions in which cooling of the passenger compartment is desired and the cooling circuit is temporarily inactive so as to exploit to the maximum the cold accumulated in the radiator for keeping the passenger compartment cooled. 
     
     
         3 . The system according to  claim 1 , wherein said control means are electronic control means programmed for activating the step of accumulation of cold in the radiator also in the steps of deceleration of the vehicle. 
     
     
         4 . A method for controlling an air-conditioning system of a motor vehicle, wherein said system comprises:
 an evaporator for cooling the air, forming part of a cooling circuit, and interposed in a path of a flow of air;   a radiator for heating the air, connected to the circuit of the liquid for cooling the engine and set in the aforesaid path of the flow of air, downstream of the evaporator; and   a mixing valve for directing the flow of air leaving the evaporator all through the heating radiator, or else all directly to the passenger compartment, without passing through the heating radiator, or else part through the heating radiator and part directly to the passenger compartment,   wherein, in the connection between the heating radiator and the circuit of the liquid for cooling the engine, pass valve is provided that can be activated for excluding the heating radiator from the circuit of the liquid for cooling the engine, and   in that, when heating of the passenger compartment is not required and the cooling circuit is active, the aforesaid by-pass valve is activated and the aforesaid mixing valve is set in an intermediate position so that in said condition the radiant mass of said heating radiator functions as accumulator of cold, which can subsequently be used for keeping the passenger compartment cooled also during a temporary deactivation of the cooling circuit.   
     
     
         5 . The method according to  claim 4 , wherein said mixing valve is kept in the aforesaid intermediate position when heating of the passenger compartment is not required and the cooling circuit is active, whilst said mixing valve is set in a position where the entire flow leaving the evaporator is forced to pass through said heating radiator to exploit the cold accumulated therein when cooling of the passenger compartment is required and the cooling circuit is temporarily deactivated. 
     
     
         6 . The method according to  claim 4 , wherein the step of accumulation of cold in the heating radiator is also activated during the steps of deceleration of the vehicle.