METHOD AND APPARATURS FOR COOLING AIR IN AIR-CONDITIONING SYSTEMS OF MOTOR VEHICLES The invention comprise a method and an apparatus for cooling the air in air-conditioning systems of motor vehicles. The system utilizes a jet pump, also known as a thermocompressor. The essence of the invention is the utilization of waste heat from an internal combustion engine as the driving force of the air cooling process. The heat is transferred from the engine to a vapour generator by a heating medium having the form of a hot liquid circulating in the cooling system of the internal combustion engine. As a result, in the vapour generator, a working medium with high pressure and temperature is produced, which flows from the vapour generator to a jet pump, and reaches high speed in the nozzle of the jet pump owing to its adequately high pressure. High kinetic energy of the jet of working medium is used to draw coolant vapours from the low-temperature evaporator, in accordance with Venturi's phenomenon.

The method invented has the advantage of using the same organic substance as the working medium and as the coolant.

The essence of the invention are two components of the system: the vapour generator and the jet pump, connected in series and installed between the pump and the air-cooled condenser, and the fact that the low-temperature evaporator is situated between the pump and the jet pump, in parallel with the vapour generator, the generator being supplie with the heating medium.

An advantage of the invention is the elimination of the need for power- consuming, high-rpm mechanical compressor of complex construction. In the solution proposed it is not necessary to compress vapours of the circulating medium with a mechanical compressor. The jet pump applied is a simple, reliable, and relatively inexpensive device without moving parts.

Another advantage of the invention is the kinetic energy of the working medium used as the driving force of the cooling process. The energy is generated in the vapour generator by means of the waste heat from an internal combustion engine. The heat, usually carried away to the environment through the cooling system of the engine, in the solution described is used to produce pressurized jet of working medium vapours. By eliminating a power-consuming mechanical compressor, the conditioned air can be cooled without imposing additional load on the engine, and therefore without increasing fuel consumption. The solution proposed permits continuous cooling of air for the air-conditioning system with no harm to fuel economy.

An additional virtue of the invention is the possibility of drying the air during the cooling process by means of the condensation of steam contained in the air.

Air dried in that manner can be used to prepare air-fuel mixture for the fuel supply system of the internal combustion engine. Steam contained in the air-fuel mixture delivered to the combustion chamber of the internal combustion engine reduces its efficiency. As a result of drying the supplied air, the overall efficiency of the engine increases. With increased efficiency of the engine, the solution described herein can be commonly used in motor vehicles with engines having low power output.

An example of the implementation of the method and apparatus invented is shown in Figure 1, containing a scheme of the working medium and coolant circuits in the air-conditioning system of a motor vehicle, including a jet pump as a part of the system.

The invented method of cooling the air in air-conditioning systems of motor vehicles consists in the exchange of heat between a low temperature medium and a high temperature medium, and utilizes the relationship between evaporation temperature and gas pressure. Low pressure in the low-temperature evaporator (P2) is generated by the jet pump (_). The waste heat from the internal combustion engine acts as the driving force of air cooling process (1). The heat is transferred from the engine to the vapour generator (PI) by a heating medium (;)) having the form of a hot liquid circulating in the cooling system of the internal combustion engine. As a result, in the vapour generator (P1), a working medium (01) with high pressure and temperature is generated, flowing from the vapour generator (P1) to the jet pump (T), and reaching considerably high speeds in the nozzle of the jet pump (T) owing to sufficiently high pressure of the working medium (01). The kinetic energy of the jet of working medium (01) is used to draw coolant vapours (02) from the low-temperature evaporator (P2), in accordance with Venturi's phenomenon. The jet pump (I) draws the vapours of coolant (02) contained in the low-temperature evaporator (P2), keeping low pressure (0,5 to 5,0 bars) and low temperature (+5 to +15°C) of the coolant (02) in the evaporator (P2). The coolant (02) evaporates in the evaporator (P2), utilizing heat captured from the medium being cooled (1), which has the form of warm and humid air having a temperature of +20 to +40°C, drawn from the outside of the vehicle. The coolant (02) chills the warm air to a sufficiently low temperature (+5 to +15°C), and causes condensation of steam (la) which is drained out of the vehicle. In this process, the air (1) is cooled and dried simultaneously. Cool and dry air (1b) is blown into the motor vehicle interior in order to lower the inner temperature to the level providing the assumed level of thermal comfort. The air can be also used to prepare air-fuel mixture needed by the fuel supply system of the internal combustion engine.

The apparatus invented consists of a vapour generator (P1), a low- temperature evaporator (P2), a jet pump (T), an air-cooled condenser (S), a pump (Po), a throttling valve (Z), and hydraulic conduits (H) connecting all components of the system. In the apparatus invented, the working medium (01) and the coolant (02) are the same organic substance (0) of different pressure and temperature parameters. The air drawn from the outside of the motor vehicle (1) is the medium being cooled, and the hot liquid circulating in the internal combustion engine cooling system is utilized as the medium (3) heating the vapour generator (PI). The complete equipment is installed in a motor vehicle.