FR3033194A1 - TRANSCRITIC AIR CONDITIONING CIRCUIT WITH INTEGRATED EXPANSION VASE - Google Patents

Abstract

Transcritical operating cycle air conditioning device (1), the device comprising a circuit (4) conveying a refrigerant fluid (5) and successively connecting: - the outlet (6) of a compressor (7); - a gas cooler (8); - the cold circuit (9) of an intercooler (10); an expander (11); - a second exchanger (12) having a volume (31, 71) for circulating a cooling fluid (21) in heat exchange with the refrigerant fluid (5); the inlet (13) of the hot circuit (14) of the intercooler (10); the air conditioning device (1) being characterized in that the second type exchanger (12) comprises an expansion volume of the cooling fluid (21).

Description

FIELD OF THE INVENTION The present invention relates to the field of air conditioning and more particularly to air conditioning circuits with transcritical operation. BACKGROUND OF THE INVENTION The air conditioning devices of the passenger compartment of a vehicle are widespread, regardless of the type of engine of the vehicle. Conventionally, an air conditioning device operates according to a subcritical vapor compression operating cycle using a fluid such as that produced under the reference R134a (1,1,1,2-tetrafluoroethane). A thermodynamic cycle is said to be subcritical when operating below the critical temperature of the fluid. The critical temperature of a fluid is its maximum temperature in the liquid phase, whatever the pressure, that is to say the temperature of its critical point. The use of fluids such as the fluid R134a will soon be banned because of its significant greenhouse effect. Among the alternatives, carbon dioxide (CO2), also known as R744, appears to be the most promising replacement for future air conditioning systems. However, because of the low critical temperature (31 degrees Celsius) of CO2, an air conditioning system employing CO2 must adopt a transcritical operating cycle, ie involving higher temperatures / pressures. at the temperature / critical pressure of the fluid. The equipment usually used for subcritical duty cycle circuits is not suitable for transcritical operating cycles and must be rethought.

Conventionally, a transcritical cycle of air conditioning circuit comprises a rotary compressor driven, via a clutch, by a rotating element of the vehicle engine. Referring to Figure 1, this compressor 60 compresses a refrigerant fluid and directs it to a gas cooler 61 attached to a fan. The fan forces a flow of air through the gas cooler 61 to remove a maximum of calories from the compressed fluid. The refrigerant fluid is then directed to the cold circuit of an internal heat exchanger 62 in which the refrigerant fluid still gives heat to a portion of the circuit corresponding to the hot circuit of the internal heat exchanger 62. The coolant fluid thus cooled is then directed to a pressure reducer 63 which relaxes the coolant fluid and directs it to a "chiller" type exchanger (or water chiller in French) 64. The "chiller" type exchanger 64 is connected to a cooling circuit. Cooling 65 in which circulates a cooling fluid in heat exchange with the refrigerant coolant circuit also comprises an expansion vessel whose function is to provide an expansion volume absorbing the variations in the volume of the cooling fluid.

As car manufacturers wish to offer compact and inexpensive vehicles as possible, there is a need for compact and economical transcritical cycle air conditioning systems.

OBJECT OF THE INVENTION An object of the invention is to reduce the size and the costs of manufacturing and mounting a transcritical cycle air conditioning circuit.

SUMMARY OF THE INVENTION For this purpose, there is provided a transcritical operating cycle air conditioning device, comprising a circuit conveying a refrigerant fluid and successively relying on: the output of a compressor; - a gas cooler; - the cold circuit of an intercooler; An expander; - A second heat exchanger of the air conditioning device having a circulation volume of a refrigerant in heat exchange with the coolant fluid; the inlet of the hot circuit of the intermediate cooler. The output of the hot cooler circuit is connected to the compressor inlet. According to the invention, the second exchanger comprises an expansion volume of the cooling fluid. Thus, the overall size of the second exchanger and expansion vessel is reduced by merging these two components. The risk of fluid leakage is also reduced by a reduction in the number of conduits. Finally, manufacturing and assembly operations are simplified, all resulting in a more reliable device, more compact and less expensive than the previous solutions. The invention also comprises a second exchanger for a transcritical air conditioning circuit, comprising a bundle of circulating coolant fluid tubes which extend in a circulation volume of a refrigerant fluid. The second exchanger comprises an expansion volume of the cooling fluid. The circulation volume of the cooling fluid of such an exchanger is advantageously of substantially parallelepipedal shape and is delimited by a body comprising a first molded element and a second element attached by stapling on the first. This method of assembly is particularly economical and reliable.

According to a particular embodiment, the first element has a substantially parallelepipedal shape and the second element is substantially plane. Alternatively, the first element and the second element are both substantially parallelepipedal in shape. Thus, it is possible to provide exchangers for transcritical air conditioning circuit having two different refrigerant circulation volumes and having a large number of parts in common, which contributes to reducing the unit price of each exchanger. Finally, at least one of the elements comprises at least one groove for receiving the flanks of a collector of the circulating fluid flow tube bundle.

This facilitates the relative positioning of the different components of the second exchanger during assembly and thus reduces its manufacturing cost. Other features and advantages will become apparent upon reading the following description of non-limiting embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Reference will be made to the accompanying drawings, in which: FIG. 1 is a diagrammatic representation of a prior art transcribing air conditioning circuit; FIG. 2 is a schematic representation of an air conditioning circuit with transcritical operation according to the invention; FIG. 3 is a perspective view of a first embodiment of a second exchanger according to the invention; Figure 4 is a perspective view of the exchanger of Figure 3 after a 90 'rotation; FIG. 5 is an exploded perspective view of the exchanger of FIG. 4; - Figure 6 is a section along a plane VI-VI of the exchanger of Figure 4; FIG. 7 is a perspective view of a second embodiment of a second exchanger according to the invention; - Figure 8 is a perspective view of the exchanger of Figure 7 after a 90 'rotation; FIG. 9 is an exploded perspective view of the exchanger of FIG. 8. DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 2, the transcritical operating cycle cooling device, generally designated 1, is mounted in a motor compartment 2 of a vehicle 3 with an internal combustion engine (not shown). The device 1 comprises a circuit 4 conveying a coolant fluid 5, here CO2, in one direction represented by the arrows. The circuit 4 connects successively: the output 6 of a compressor 7; a gas cooler 8; The cold circuit 9 of an intermediate cooler 10; an expander 11; a second exchanger 12 of the air conditioning device; and the inlet 13 of the hot circuit 14 of the intermediate cooler 10. The outlet 15 of the hot circuit 14 of the aftercooler 10 is, in turn, connected to the inlet 16 of the compressor 7.

A cooling circuit 20 conveys a cooling fluid 21, here glycol water, through a circulation pump 22. The circuit 20 comprises a fluid / air heat exchanger 23 through which a fan 24 forces a flow of water. 3. The cooling fluid 21 enters the second exchanger 12 in order to lose calories absorbed by the change of state of the coolant 5 in the second exchanger 12. The second exchanger 12 can be used as a "chiller" type chiller or water chiller in French. In such a use, this type of exchanger operates as an exchanger capable of creating cold for an exchange with a cooling fluid of another circuit of the motor vehicle, particularly when the latter comprises batteries. The second heat exchanger may also be used as a condenser type exchanger or as a gas cooler exchanger cooled with a coolant (such as, for example, brine). A first embodiment of the second heat exchanger 12 will now be described with reference to FIGS. 3 to 5. The second heat exchanger 12 comprises a body 30 of substantially parallelepipedal shape delimiting an interior volume 31 containing a tubular bundle 50. body 30 comprises a first molded element 32 of substantially parallelepiped shape on which is reported a second element 33 substantially planar. The elements 32 and 33 are secured to one another by a plurality of staples 34 integrated in the second element 33. The first element 32 has an open face 35 and is provided with a plurality of outer ribs 36. reinforcing its resistance to pressure. The first member 32 includes a first internal peripheral groove 37 and a second identical groove 38. The grooves 37 and 38 are respectively located at the upper end 39 and at the lower end 40 of the first element 32. The first element 32 also comprises a first and a second tubular connection 41 and 42 respectively emerging in an upper and lower portion of the inner volume 31. As shown in the figures, the connectors 41 and 42 project from two opposite faces of the first element 32, one near the upper end 39 and the Another portion near the lower end 40. A portion 43 of substantially parallelepiped shape is connected by its base to the upper end 39 of the first element 32. The portion 43 is in fluid connection with the volume 31 because its base is recessed.

A plug 44 located on the opposite side to the base of the portion 43 provides access to the inner volume 43.1 of the portion 43. The second member 33 includes a first tubular connector 45 and a second tubular connector 46 de- plugging in the volume 31 respectively facing the grooves 37 and 38. The tubular bundle 50 comprises, here, seven tubes 51 parallel to each other and of rectangular section. The tubes 51 comprise crenellations 51.1 which increase the exchange surface of the tubes with the medium in which they extend. The tubes 51 extend into the volume 31 from an inlet manifold 52 to an outlet manifold 53. Each manifold 52 and 53 has a substantially parallelepipedal shape and has respectively a sealing member 54 and 55. 8), the flanks of the collectors 53 and 54 of the tubular bundle 50 are respectively placed in the grooves 38 and 37 of the groove. first element 32. The second element 33 is then presented in such a way that the sealing elements 54 and 55 respectively engage in the tubular portions of the connectors 46 and 45. The second element 33 is then brought into contact with the first element 33. element 32 and the elements 32 and 33 are secured by means of the clips 34. The second exchanger 12 thus formed thus comprises a tubular bundle 50 extending in a volume in interior 31 between the two collectors 52 and 53.

The second heat exchanger 12 also comprises the internal volume 43.1 of the portion 43 in fluidic connection with the volume 31. The second heat exchanger 12 is connected to the air conditioning device 1 so that the refrigerating fluid 5 at the outlet the regulator 11 enters the inlet manifold 52 via the connector 46 and leaves the outlet manifold 53 via the connector 45. The inlet of the exchanger 23 is connected to the connector 42 and the outlet of the exchanger 23 is connected to the connection 41. In operation, the expanded coolant 5 evaporates in the tubes 51 of the tubular bundle 50 and cools the coolant 21 circulating in the internal volume 31 under the effect of the circulation pump 22. In the case of a variation of the volume of cooling fluid 21 produced by a change in ambient pressure or a large heat to be evacuated, the volume 43.1 allows the expansion of the cooling fluid 21. 4 3.1 being situated above the connection 41 of the cooling fluid outlet 21, the latter is little or not occupied by the cooling fluid 21 and forms an expansion volume of the latter. Elements identical or similar to those previously described will bear a numerical reference identical thereto in the description which follows of a second embodiment of the invention with reference to FIGS. 7 to 9. The body 30 the second exchanger 12 is of substantially parallelepipedal shape and comprises a first molded element 32 of substantially parallelepipelic shape, open on one of its faces. A second element 70 also substantially parallelepipedic comprises an open face on which is reported the open face of the element 32. The bodies 32 and 70 thus define an internal volume 71 for circulation of the cooling fluid 21. The elements 32 and 70 are secured to one another by a plurality of staples 34. The connection between the two elements 32 and 70 can be achieved by staples, screws, or by induction or vibration welding. The second member 70 is provided with a plurality of outer ribs 36 reinforcing its resistance to pressure; as well as a first internal peripheral groove 72 and a second internal peripheral groove 73 identical to the groove 72. The grooves 72 and 73 are located respectively at the upper end 74 and at the lower end 75 of the second element 70. The second element 70 comprises a first tubular connector 45 and a second tubular connector 46 opening into the volume 71 respectively facing the grooves 72 and 73. The tubular bundle 80 comprises, here, fourteen 30 tubes 51 extending in the volume 71 from the inlet manifold 52 to the outlet manifold 53. During the manufacture of the second exchanger 12, the flanks of the collectors 53 and 54 of the tubular bundle 80 are respectively placed in the grooves 38 and 37 of the first element 32. The second member 70 is then presented in such a way that the grooves 73 and 72 face the flanks of the collectors 53 and 54. In this position, the Sealing elements 54 and 55 engage respectively in the tubular portions of the connectors 46 and 45. The second element 70 is then brought into contact with the first element 32 and the elements are secured by stapling. The second heat exchanger 12 thus formed thus comprises a tubular bundle 80 providing an exchange surface of fourteen tubes 51. The manufacture of the second heat exchanger according to this second embodiment implements an important part of common or identical elements. with the first embodiment, resulting in reduced manufacturing and tooling costs.

Of course, the invention is not limited to the embodiments described but encompasses the whole variant within the scope of the invention as defined by the claims. In particular: although here the circuit directly connects the various components of the air-conditioning device, the invention also applies to components connected to one another via other components such as a desiccator, control or regulating devices, valves or the like; - Although here the refrigerant fluid is CO2, the invention is also applicable to other types of refrigerant fluids suitable for operation in transcritical cycle; Although here the cooling fluid is glycol water, the invention is also applicable to other types of refrigerant fluids, for example alcohol, salt water, ammonia or chloride. ammonium; Although here the elements constituting the body of the second heat exchanger are made by molding, the invention is also applicable to other embodiments of the elements, such as, for example, stamping, forming, welding mechanics. or machining; - Although here the body elements are linked to each other by stapling, the invention also applies to elements linked together by other assembly means such as welding, the Screwing, gluing; - Although here the connections reported on the body of the second heat exchanger are tubular, the invention is also applicable to other types of connectors such as bayonet connectors or cartridges; Although here the tubes of the bundle of tubes are crenellated and seven or fourteen in number, the invention also applies to tubes of any shape different in number, such as for example smooth tubes.

Claims (8)

REVENDICATIONS1. Transcritical operating cycle air conditioning device (1), the device comprising a circuit (4) conveying a coolant fluid (5) and successively connecting the outlet (6) of a compressor (7); - a gas cooler (8); the cold circuit (9) of an intermediate cooler (10); an expander (11); - a second exchanger (12) having a volume (31, 71) for circulating a cooling fluid (21) in heat exchange with the refrigerant fluid (5); the inlet (13) of the hot circuit (14) of the intercooler (10), the outlet (15) of the hot circuit (14) of the intercooler (10) being connected to the inlet (16) of the compressor (7). ), the air conditioning device (1) being characterized in that the second heat exchanger (12) comprises an expansion volume (43.1) of the cooling fluid (21). 2. Device (1) according to claim 1, wherein the expansion volume (43.1) of the second heat exchanger (12) also comprises an access cap (44). 3. Heat exchanger (12) for a transcritical operation air conditioning device (1), comprising a bundle (50) of coolant circulation tubes (51) which extend in a volume (31, 71) for circulating a cooling fluid (21), said exchanger (12) comprising an expansion volume (43.1) of the cooling fluid (21). 3033194 13 4. Exchanger (12) according to claim 3, comprising an access plug (44) to the expansion volume (43.1) of the cooling fluid (21). 5 5. Exchanger (12) according to claim 3, wherein the volume (31, 71) of circulation of the cooling fluid (21) is of substantially parallelepiped shape and is delimited by a body (30) comprising a first element (32). ) and a second member (33, 70) stapled to the first member (32). 6. The exchanger (12) of claim 5, wherein the first member (32) is substantially parallelepipedal in shape and the second member (33) is substantially planar. 7. Exchanger (12) according to claim 5, wherein the first element (32) and the second element (70) are of substantially parallelepiped shape. 8. Exchanger (12) according to claim 5, wherein at least one of the elements (32, 70) comprises at least one groove (37, 38, 72, 73) for receiving the flanks 25 of a collector ( 52, 53) of the beam (50) of tubes (51) for circulating the coolant fluid (5).