FR2904791A1 - Motor vehicle`s cab interior refrigerating method, involves pre-cooling fluid between compression and regulation of fluid, in exchanger where fluid is cooled by heat exchange with coolant that cools engine and circulates in exchanger - Google Patents

Abstract

The method involves compressing refrigerant fluid i.e. carbondioxide gas, in a compressor (44), and cooling the fluid in a cooler (48) with a cooling ventilator (56). The fluid is regulated in a regulator (52) and evaporated in an evaporator (54) placed in a direct heat exchanging relation with a cab interior (13) of a motor vehicle (10). The fluid is pre-cooled between compression and regulation of the fluid, in a pre-cooling heat exchanger (46) where the fluid is cooled by heat exchange with a coolant e.g. glycol water, that cools a vehicle`s heat engine (12) and circulates in the exchanger. An independent claim is also included for a cab interior refrigerating assembly comprising a compressor.

Description

Refrigeration process of a passenger compartment of a motor vehicle, together

  refrigeration and associated motor vehicle. The present invention relates to a refrigeration method of a passenger compartment of a motor vehicle, of the type comprising the following steps: - compression of a refrigerant in a compressor; cooling of the refrigerant fluid from the compressor in a cooler provided with a fan; - Expansion of the refrigerant fluid from the cooler in the expander; - Evaporation of the refrigerant in an evaporator placed in heat exchange relationship with the passenger compartment of the motor vehicle. It is known from EP-A-0 991 536 a process of the aforementioned type, implemented in an air conditioning circuit successively comprising a compressor, a cooler, a pressure reducer and an evaporator placed in heat exchange relation with the passenger compartment of the vehicle.

  In summer, in a conventional mode of operation for the cooling of the passenger compartment, the refrigerant present in the circuit is compressed in the compressor, then cooled in the cooler before being de-stretched and evaporated successively in the regulator and in the the evaporator. Expansion and evaporation of the refrigerant generate frigories necessary for cooling the passenger compartment. In a particular mode of operation, when the passenger compartment must be heated in winter, the refrigerant fluid from the compressor is sent to a heat exchanger placed in heat exchange relation with the coolant for cooling the engine, and is sent di - right to the regulator without going through the cooler. This mode of operation makes it possible to preheat the coolant when the engine is cold, and to provide calories to the cabin of the vehicle before the engine reaches its operating temperature. Such a method is not entirely satisfactory as regards its operation for generating frigories with a view to refrigerating the passenger compartment.

Indeed, the refrigeration process is not fully optimized in terms of energy and the consumption of the compressor and the fan unit associated with the cooler could be optimized. An object of the invention is therefore to obtain a refrigeration process 5 of a passenger compartment of a motor vehicle which has an improved efficiency. For this purpose, the subject of the invention is a process of the aforementioned type, characterized in that the process comprises, between the compression step and the expansion step, a step of pre-cooling the refrigerant in a pre-cooling heat exchanger , in which the refrigerant fluid from the compressor is cooled by heat exchange with a coolant for cooling the vehicle engine, flowing in the pre-cooling heat exchanger. The process according to the invention may comprise one or more of the following characteristics, taken separately or in any technically possible combination: all the refrigerant fluid from the compressor passes continuously into the heat exchanger pre-cooling when the compressor is in operation; the heat transfer fluid passing through the pre-cooling exchanger 20 circulates on a cooling branch of the engine continuously supplied when the engine is activated; and - the heat transfer fluid passing through the pre-cooling exchanger circulates on a branch of the engine cooling circuit fed intermittently when the engine is activated.

The invention further relates to a refrigeration assembly of a passenger compartment of a motor vehicle, of the type comprising: a refrigerant compressor; a refrigerant cooler connected to the compressor; - a refrigerant expansion valve, connected to the cooler; - A refrigerant evaporator connected to the expander and placed in heat exchange relationship with the passenger compartment of the motor vehicle; characterized in that it comprises a heat exchanger coolant pre-cooling, placed between the compressor and the deputy and placed in heat exchange relationship with a heat transfer fluid for cooling the engine of the motor vehicle, the pre-cooling heat exchanger being connected in series with the compressor, the cooler and the expander so that all the refrigerant fluid from the compressor is continuously circulating in the pre-cooling exchanger when the compressor is in operation. The assembly according to the invention may comprise one or more of the following characteristics, taken separately or according to any technically possible combination: the precooling heat exchanger is placed between the compressor and the cooler; it comprises a branch of a cooling circuit of the motor capable of being continuously supplied with power when the motor is activated, the pre-cooling heat exchanger being placed in heat exchange relation with the branch fed continuously; and - it comprises a branch of the engine cooling circuit capable of being fed intermittently when the engine is activated, the pre-cooling heat exchanger being placed in heat exchange relation with the branch fed intermittently.

The invention also relates to a motor vehicle, characterized in that it comprises a refrigeration assembly as defined above. The invention will be better understood on reading the following description, given solely by way of example, and with reference to the appended drawings, in which: FIG. 1 is a diagrammatic view of a first set of refrigeration of a passenger compartment of a motor vehicle according to the invention; FIG. 2 is a view similar to FIG. 1 of a second refrigeration unit of a motor vehicle passenger compartment according to the invention; and FIG. 3 is a view similar to FIG. 1 of a third refrigeration unit of a passenger compartment of a motor vehicle according to the invention.

In all that follows, the terms upstream and downstream agree with respect to the direction of normal flow of a fluid in an installation. The motor vehicle 10 diagrammatically and partially shown in FIG. 1 comprises, in a conventional manner, a heat engine 12, a passenger compartment 13, and a first refrigeration unit according to the invention comprising a closed circuit 14 for cooling the heat engine. 12, and a closed circuit 18 for refrigeration of the passenger compartment. Typically, the cooling circuit 14 of the engine 12 contains a coolant consisting for example of brine. It comprises a pump 20 for circulating the coolant, a circulation network 22 in the engine 12, and a water outlet box 24. The heat transfer fluid circulating network 22 in the engine de-mouth upstream in the pump 20, and downstream in the water outlet box 24.

The circuit 14 further comprises a branch 26 for circulating the heat transfer fluid in a heater 28, a branch 30 for circulating the refrigerant in a radiator 32, and a branch 34 for circulating the refrigerant in a heat exchanger 36 for cooling the refrigerant. engine oil.

The heater 28 is placed in direct heat exchange relation or via a fan with the passenger compartment 13 of the motor vehicle. It is connected upstream to the water outlet box 24, and is connected downstream to the pump 20 via a heater outlet pipe 38. The radiator 32 is for example placed on the front face (not shown) of the motor vehicle 10. It is provided with a fan 40 for scanning the radiator. The radiator 32 is connected upstream to the pump 20, and downstream to the water outlet box 24. The branch 26 of circulation in the heater 28 and the branch 30 of circulation in the radiator 32 are connected in parallel between the pump 20 and the water outlet box 24. A distributor 42 is placed in the water outlet box 24 for re-starting the heat transfer fluid flow between the branch 26 and the branch 30.

The exchanger 36 for cooling the engine oil is placed in heat exchange relation with the oil circulating in the engine. It is connected, upstream and downstream, to the network 22. As soon as the motor 12 is in operation, the branches 26, 30 and 34 are permanently supplied with heat transfer fluid pumped by the pump 20. The refrigeration circuit 18 of the passenger compartment 13 includes, successively in series, a compressor 44, a pre-cooling heat exchanger 46, a cooler 48, and an internal cooler 50. It further comprises an expander 52, and an evaporator 54 placed in connection with each other. heat exchange with the passenger compartment 13. The refrigeration circuit 18 contains a refrigerant fluid consisting for example of a carbon dioxide type gas. The pre-cooling exchanger 46 is connected upstream to the compressor 44, and downstream to the cooler 48 by non-bypass lines. Thus, all the refrigerant from the compressor 44 passes permanently into the pre-cooling exchanger 46 before entering the cooler 48 when the compressor 44 is activated. The pre-cooling heat exchanger 46 is also mounted on the air heater outlet duct 38 between the heater 28 and the pump 20. Thus, the refrigerant circulating in the refrigeration circuit 18 of the passenger compartment between the compressor 44 and the cooler 48 is placed in heat exchange relation in the exchanger 46 with the heat transfer fluid for cooling the motor 12 flowing in the branch 26 between the water outlet box 24 and the pump 20. In the exchanger 46, the coolant and the coolant are not mixed. The cooler 48 is placed on the front face (not shown) of the motor vehicle. It is equipped with a cooling fan 56. The internal heat exchanger 50 is connected in series with the pipe connecting the cooler 48 to the expansion valve 52 and the pipe connecting the evaporator 54 to the compressor 44. It thus places the cooling fluid from the cooler 48 in heat exchange relation with the refrigerant leaving the evaporator 54.

A first method of refrigerating the passenger compartment 13 of the motor vehicle according to the invention will now be described. Initially, when the engine 12 of the vehicle 10 is started, the temperature of the heat transfer fluid is substantially equal to the ambient temperature. Once the engine is on, the pump 20 is activated. The heat transfer fluid then circulates in the network 22 to cool the motor 12. It also circulates permanently in the branch 34 of circulation in the exchanger 36 for cooling the engine oil. Similarly, the heat transfer fluid from the water box 24 is distributed by the distributor 42 between the branch 26 of circulation in the heater 28 and the branch 30 of circulation in the radiator 32. These branches 26, 30 are supplied with continuously by circulating coolant as soon as the motor 12 is in operation. When a user of the motor vehicle 10 operates the refrigeration circuit 18 of the passenger compartment, the compressor 44 is activated to circulate the refrigerant in the refrigeration circuit 18. The pressure of the refrigerant at the outlet of the compressor 44 before its entry into the pre-cooling exchanger 46 is for example 130 bar absolute, and its temperature is 180 C.

In the exchanger 46, the high temperature coolant is placed in a heat exchange relationship with the coolant at ambient temperature for cooling the engine 12. Since the heat engine 12 is not yet hot, the coolant is cooled in the exchanger 46, before being introduced into the cooler 48.

In the cooler 48, the compressed refrigerant is further cooled to a temperature substantially equal to 50 C. Then, the coolant from the cooler 48 is introduced into the internal heat exchanger 50, where it cools down again. at a temperature substantially equal to 35 C.

The refrigerant from the internal exchanger 50 is then expanded in the expander 52 to a pressure substantially equal to 35 bar. During this expansion, the temperature of the refrigerant decreases to about 0 C. The coolant partially condenses.

Then, the cooled cooled refrigerant is partially evaporated in the evaporator 54, which generates frigories for the cooling of the passenger compartment 13. The heated refrigerant fluid from the evaporator 54 is then introduced into the refrigerator. internal heat exchanger 50 for cooling the refrigerant fluid from the evaporator 48. It heats up to a temperature substantially equal to 40 C before being introduced again into the compressor 44. The refrigerant fluid from the compressor 44 being pre-cooled completely in the pre-cooling exchanger 46, the fan speed 56 of the cooler 48 can be greatly reduced, especially when the vehicle has a zero speed and the motor 12 is still activated. Thus, the consumption generated by the fan 56 is reduced, which contributes to increasing the efficiency of the air conditioning circuit 18. The consumption of the compressor 44 can be reduced significantly, since the pressure at the outlet of this compressor can be reduced while always producing the same number of frigories. In addition, when the need for cooling of the passenger compartment 13 is very high, it is possible to run the fan 56 and the compressor 44 at full speed by increasing the maximum performance of the refrigeration circuit 18 for the production of frigories. in the evaporator 54. The second refrigeration assembly shown in FIG. 2 differs from the first refrigeration assembly in that the pre-cooling heat exchanger 46 is connected in series with the coolant circulation branch 34 in the heat exchanger 36. cooling the engine oil, not on the branch 26 of circulation in the heater 28. The refrigeration process implemented in this set is otherwise similar to that implemented in the first set. The third refrigeration assembly according to the invention, shown in FIG. 3, differs from the first assembly in that it comprises an exhaust gas cooling circuit 70 comprising an additional pump 72 and a heat exchanger 74 mounted in series. .

Such a circuit is for example described in the French patent application No. 0550416 of the Applicant. The pump 72 is connected upstream to a tapping 76 provided on the circulation branch 30 in the radiator 32, placed at an outlet of the radiator 32. The exchanger 74 is connected downstream to a tapping 78 on the branch 30 circulation, located at an inlet of the radiator 32. In this assembly, the pre-cooling heat exchanger 46 is formed by the heat exchanger 74 which is connected upstream to the compressor 44 and downstream to the cooler 48. In the exchanger 74 , the refrigerant circulating in the refrigeration circuit 18 is placed in heat exchange relation with the coolant circulating in the exhaust gas cooling circuit 70. The refrigeration method implemented in this third set is analogous to that implemented in the first set. However, the pump 72 is activated intermittently when the motor 12 is running. When the pump 72 is activated, the pre-cooling exchanger 76 allows the pre-cooling of the refrigerant present in the refrigeration circuit 18 and flowing between the compressor 46 and the cooler 48. In a variant, the refrigeration circuit 18 is devoid of of in-dull heat exchanger 50.

Claims (9)

  1. A method of refrigerating a passenger compartment (13) of a motor vehicle (10), of the type comprising the following steps: - compressing a refrigerant in a compressor (44); 5 - cooling the coolant from the compressor (44) in a cooler (48) provided with a fan (56); - Expansion of the coolant from the cooler (48) in the expander (52); - evaporation of the refrigerant in an evaporator (54) placed in heat exchange relationship with the passenger compartment (13) of the motor vehicle (10), characterized in that the process comprises, between the compression step and the an expansion step, a step of pre-cooling the refrigerant in a pre-cooling heat exchanger (46), in which the refrigerant from the compressor (44) is cooled by heat exchange with a coolant for cooling the engine (12) of the vehicle (10) circulating in the pre-cooling heat exchanger (46).   2. Method according to one of claims 1, characterized in that all of the refrigerant fluid from the compressor (44) permanently passes into the pre-cooling heat exchanger (46) when the compressor (44) is in operation. .   3. A process according to any one of the preceding claims, characterized in that the heat transfer fluid passing through the pre-cooling exchanger (46) circulates on a cooling branch of the motor (12) continuously supplied when the engine (12) is activated.   4. A process according to any one of claims 1 to 2, characterized in that the heat transfer fluid passing through the pre-cooling exchanger (13) circulates on a branch of the engine cooling circuit (12) fed intermittently when the motor (12) is activated.   5. A refrigeration unit of a passenger compartment (13) of a motor vehicle (10), of the type comprising: a compressor (44) for refrigerant fluid; A refrigerant cooler (48) connected to the compressor (44); - a refrigerant expander (52) connected to the cooler (48); - an evaporator (54) of refrigerant fluid connected to the expander (52) and placed in heat exchange relation with the passenger compartment (13) of the motor vehicle (10); characterized in that it comprises a heat exchanger (46) for pre-cooling the refrigerant fluid, placed between the compressor (44) and the expander (52) and placed in heat exchange relation with a coolant for cooling the motor ( 12) of the motor vehicle (10), the pre-cooling heat exchanger (46) being connected in series with the compressor (44), the cooler (48) and the expander (52) so that all the refrigerant from the compressor (44) is continuously circulating in the precooling heat exchanger (46) when the compressor (44) is in operation.   6. An assembly according to claim 5, characterized in that the pre-cooling heat exchanger (46) is placed between the compressor (44) and the cooler (48).   7. An assembly according to any one of claims 5 or 6, characterized in that it comprises a branch (26; 30; 34) of a cooling circuit of the motor (12) able to be fed continuously when the motor (12) is activated, the pre-cooling heat exchanger (46) being placed in heat exchange relation with the continuously energized branch (26; 30; 34).   8.- assembly according to any one of claims 5 to 6, characterized in that it comprises a branch (70) of the engine cooling circuit adapted to be fed intermittently when the motor (12) is activated, the exchanger precooling heat exchanger (46) being placed in heat exchange relationship with the intermittently energized branch (70).   9. A motor vehicle (10) characterized in that it comprises a refrigeration unit according to any one of claims 5 to 8.