BRPI1005089B1 - Internal heat exchanger for vehicle climate control circuit and vehicle climate control circuit - Google Patents

Abstract

INTERNAL THERMAL EXCHANGER FOR AUTOMOTIVE VEHICLE AIR CONDITIONING CIRCUIT AND ONE SUCH CIRCUIT. The present invention relates to an internal heat exchanger of coaxial tubular type for a motor vehicle air conditioning circuit comprising two portions of low and high pressure traversed by a refrigerant, and to such an air conditioning circuit that incorporates it. This coaxial tubular exchanger (E) defines at least one radially internal channel (11) preferably for the low pressure fluid inside an inner tube (10) and one radially external channel (21) preferably for the high pressure fluid formed between that inner tube and an outer tube (20). According to the invention, spacing means (30) of thermal conductivity lower than that of the inner and outer tubes are mounted movable at least in translation between these two tubes and extend in a part only along the length of the outer channel, at least one zone of the latter devoid of these means being destined to be connected to a bypass (40), such as a valve body or a sensor support pipe, through a connection hole (23) formed in the external tube perpendicularly to that zone.

Description

The present invention relates to an internal coaxial type heat exchanger for a motor vehicle air conditioning circuit, and to such a air conditioning circuit that incorporates that heat exchanger. In certain automotive air conditioning circuits, it is necessary to perform a thermal exchange or transfer between the fluid in the high pressure portion of the circuit that is being cooled and the same fluid in the low pressure portion of that circuit that serves as a cold source and that is reheated in exchange to improve the circuit performance. An internal heat exchanger is used for this purpose, due to the fact that it does not seek exchange with the air outside the vehicle or with the air in the passenger compartment.

In a known way, a heat exchanger is of metallic type and is connected to the corresponding conduits of the air conditioning circuit, which in particular comprise flexible, via connectors mounted at each end of the exchanger, which can be, for example, of the type of plate, which consists of a stack of flat tubes and which performs the thermal exchange both by convection with the air outside the exchanger and by conduction, or of the type of multitubes which, without its simplest version, is a counter-current coaxial tubular type, which in this case performs the thermal exchange without the precited convection.

1. - na parte de dentro de um tubo interno do trocador, pelo menos um canal radialmente interno destinado a veicular o fluido proveniente da porção de baixa pressão do circuito, e
2. - radialmente entre esse tubo interno e um tubo externo que forma invólucro para o trocador, um canal radialmente externo usualmente provido de aletas longitudinais projetadas para otimizar a transferência térmica entre os fluidos que circulam nos canais interno(s) e externo que são repartidas em sua circunferência e que podem ser solidarias dos tubos interno e/ou externo ou ainda adaptadas entre esses dois tubos, como ilustrado por exemplo no documento US-A-6 434 972.

In the latter case, and notably with fluids such as R134a or R152, this coaxial exchanger generally defines:

1. - inside an inner tube of the exchanger, at least one radially internal channel designed to convey the fluid coming from the low pressure portion of the circuit, and
2. - radially between this inner tube and an outer tube that forms a shell for the exchanger, a radially outer channel usually provided with longitudinal fins designed to optimize the thermal transfer between the fluids that circulate in the inner (s) and outer channels that are distributed in their circumference and that can be solidary of the inner and / or outer tubes or even adapted between these two tubes, as illustrated for example in US-A-6 434 972.

Generally, at least one metallic female connector is used for the end of the exchanger that is welded or brazed at the same time in the inner and outer tubes of the exchanger in order to define duct passages for the fluid that communicate tightly with these internal and external channels.

Patent documents WO-A1-2007 / 013439 and EP-A1- 1762 806 show such internal heat exchangers that are respectively equipped with two female connectors and a single female connector, in both cases via three welding or brazing lines in the corresponding end of the exchanger.

A major drawback of these known coaxial internal fin exchangers is that one must refrain from making derivations in the external tube perpendicularly to these fins in order to connect notably valves or pipes that support sensors, or that the profiles that form the inner tubes must be previously machined and / or external at the location of the fins that they comprise in the area of the exchanger (usually at the extremity) precisely destined to receive these derivations, which increases the manufacturing cost of the exchangers.

Another drawback of known coaxial internal exchangers equipped with connectors is the relatively large weight of these connectors, which on the other hand must be precisely machined and then brazed or welded for their solidarity with the internal and external tubes of the exchangers, which also contributes to increase the manufacturing and assembly costs of the latter.

An objective of the present invention is to propose such an internal exchanger of coaxial tubular type comprising two portions of low and high pressure traversed by a refrigerant fluid, the exchanger defining at least one radially internal channel inside the inner tube preferably for the low pressure fluid and a radially external channel preferably for the high pressure fluid formed between that inner tube and an outer tube, an exchanger that allows to correct these inconveniences.

For this, a heat exchanger according to the invention is such that means of spacing of thermal conductivity lower than that of the inner and outer tubes are mounted movable at least in translation between these two tubes and extend axially in a part only the length of the outer channel , at least one zone of the latter devoid of these means being destined to be connected to a bypass, such as a valve body or a sensor support pipe, through a connection hole formed in the external tube perpendicularly to that zone.

It will be noted that these spacing means, according to the invention, which ensure a spacer function (that is, of crosspiece), between these tubes thus allow, due to their thermal conductivity lower than that of the latter, to avoid thermal coupling under the form of thermal bridges between these two inner and outer tubes. As an example, these spacing means can be made of a metallic material (typically of lower thermal conductivity than that of aluminum in the case of tubes based on that metal) or plastic (for example based on polyamide).

According to another feature of the invention, these spacing means, which are intended to generate turbulence for the fluid circulating within the external channel in order to optimize the thermal transfer between high and low pressure fluids, can extend axially. in a continuous or discontinuous manner over said part of the external channel ending in the recoil of at least one connecting end of the external tube.

According to a first embodiment of the invention, these spacing means are formed by several longitudinal ribs connected circumferentially between their respective bases by a substantially cylindrical wall to fit the inner tube, such that the total radial height of that wall and each rib is substantially the same as that of the external channel.

According to a second embodiment of the invention, these spacing means are formed by at least one spiral rib suitable to fit the inner tube, thereby extending in a helix around the latter according to a constant or variable pitch.

It will be noted that this adapted and sliding assembly of the spacing means between the inner and outer tubes allows to position them precisely in anticipation of the or each derivation to be made in the outer tube, making them slide previously axially outside the or each zone the derivation to leave one or more free space (s) that allow (s) that derivation (s). It is thus totally exempt from the need according to the prior art to use internal or external finned tubes locally machined in the areas intended for by-passages, which allows lowering the manufacturing cost of the exchanger.

It will also be noted that these derivations that are thus facilitated thanks to the adjustable positioning of the spacing means may for example allow the connection to the exchanger of bodies of refrigerant filling valves, pipes that support pressure or temperature sensors or any other pipe or radial connection tip (that is, whose axis is perpendicular to the axial direction of the exchanger).

According to another feature of the invention, these spacing means can be advantageously mounted in contact with the inner and outer tubes in order to serve as radial crosspieces between these tubes to ensure their concentricity. Also advantageously, in the case where the exchanger is of a type that has at least one curved or arched segment, these spacing means are preferably inserted at least in the location of that segment (s) and, even more preferably, over most of the axial length of the external channel.

It will be noted that these spacing means according to the invention thus allow to "absorb" the bending and / or bending rays of the inner and outer tubes of the exchanger in their length, which allows to maintain the passage section for the fluid within the substantially constant external channel and therefore do not hinder heat exchange in curved or arched segments.

Advantageously, a exchanger according to the invention can incorporate said branch perpendicularly to said zone of the external channel without these spacing means which is located in the vicinity of an end of the external pipe, that branch being formed by a pipe connecting the exchanger intended to convey the fluid that comes from or towards the external channel.

According to another characteristic of the invention, the exchanger can advantageously be devoid of any female high-pressure / low-pressure connector for connecting the internal (s) and external (s) channels to the air conditioning circuit. In other words, this exchanger is then exclusively made up of the inner tube, the outer tube and the so-called spacing means, which are not opposed to a derivation that communicates with the external channel and must also not be machined to allow this derivation. , as explained above.

It will be noted that this absence of a female connector (usually made of aluminum) allows to significantly reduce the mass of the exchanger according to the invention, and on the other hand its overall cost of manufacture and assembly, which in the past was burdened by the operations of machining of or of each connector.

It will also be noted that the inner and outer tubes of the exchanger according to the invention that no longer need to be machined at the level of the spacing profiles can thus be used directly after their manufacture.

According to a first embodiment of the invention, which is facilitated by the sliding assembly of the spacing means, the inner tube has at least one of its ends a surplus portion that axially exceeds the corresponding end of the outer tube being solidary to that last end and that it forms by itself - in place and instead of the preceding female connector - another pipe of connection of the exchanger designed to convey the fluid that comes from or in the direction of or of each internal channel. In that case, that end of the outer tube can be joined with the inner tube by a simple reduction of the diameter of that end, for example obtained by knurling, followed by a circumferential fixation of that end in this inner tube, for example, performed by welding, brazing, magnetic conformation ( preferably in two stages, although only one stage can be considered) or by gluing.

According to a second embodiment of the invention, which is also facilitated by the sliding assembly of the spacing means, the outer tube is attached at least at one of its ends to the inner tube by crimping with prior threading between the respective ends of these tubes from one end of a flexible tube connecting to the air conditioning circuit, which tube is optionally mounted on an axial stop against a collar of the inner tube. It will be noted that this single setting operation then allows connecting the two inner and outer tubes of the exchanger to the adjacent flexible of the air conditioning circuit.

A motor vehicle air conditioning circuit according to the invention is such that it comprises an internal heat exchanger as defined above, which is preferably connected to that circuit without a high pressure / low pressure female connector.

• a figura 1 é uma vista esquemática de um circuito de climatização para veículo automóvel que incorpora um trocador térmico interno de acordo com a invenção,
• a figura 2 é uma vista em perspectiva de um elemento de inserção de espaçamento de acordo com um primeiro exemplo da invenção a inserir no trocador térmico interno da figura 1,
• a figura 3 é uma vista parcial, em corte longitudinal e em parte em perspectiva, de uma extremidade de conexão de um trocador de acordo com esse primeiro exemplo da invenção que incorpora o elemento de inserção da figura 2,
• a figura 4 é uma vista em perspectiva de um elemento de inserção de espaçamento de acordo com um segundo exemplo da invenção a inserir no trocador da figura 1,
• a figura 5 é uma vista parcial, em corte longitudinal e em parte em perspectiva, de uma extremidade de conexão de um trocador de acordo com esse segundo exemplo da invenção que incorpora o elemento de inserção da figura 4,
• a figura 6 é uma vista parcial em perspectiva de uma extremidade de conexão de um trocador térmico interno de acordo com um primeiro modo da invenção, notadamente em referência aos exemplos das figuras 3 e 5, e
• a figura 7 é uma vista esquemática parcial em meio corte longitudinal de uma extremidade de conexão de um trocador térmico interno de acordo com um segundo modo da invenção, notadamente em referência aos exemplos das figuras 3 e 5.

Other characteristics, advantages and details of the invention will be highlighted by reading the following description of several examples of carrying out the invention, given by way of illustration and not limitation, the description being made in reference to the attached drawings, among which:

• figure 1 is a schematic view of a motor vehicle air conditioning circuit that incorporates an internal heat exchanger according to the invention,
• figure 2 is a perspective view of a spacing insertion element according to a first example of the invention to be inserted in the internal heat exchanger of figure 1,
• figure 3 is a partial view, in longitudinal section and partly in perspective, of a connecting end of a exchanger according to this first example of the invention that incorporates the insertion element of figure 2,
• figure 4 is a perspective view of a spacing insertion element according to a second example of the invention to be inserted in the exchanger of figure 1,
• figure 5 is a partial view, in longitudinal section and partly in perspective, of a connecting end of a exchanger according to this second example of the invention that incorporates the insertion element of figure 4,
• figure 6 is a partial perspective view of a connection end of an internal heat exchanger according to a first mode of the invention, notably with reference to the examples in figures 3 and 5, and
• figure 7 is a partial schematic view in half longitudinal section of a connection end of an internal heat exchanger according to a second mode of the invention, notably with reference to the examples of figures 3 and 5.

The air conditioning circuit 1 illustrated in figure 1 is known as a closed circuit or "loop" comprising, in addition to an internal heat exchanger E, several elements distributed inside the vehicle's engine compartment, notably a compressor 2, a chiller or condenser 3 and an evaporator 4, in which a refrigerant fluid under pressure, such as R134a or R152, circulates non-limitingly. All of these elements are linked together by rigid or flexible lines made up of rigid and / or flexible tubular portions, which have watertight connection means at each end.

1. - uma linha de baixa pressão BP destinada a veicular o fluido frigorígeno entre o evaporador 4 e o compressor 2, através do trocador E via uma entrada 6bp de fluido de baixa pressão a reaquecer e uma saída sbp desse fluido assim reaquecido, e
2. - uma linha de alta pressão HP destinada a veicular esse mesmo fluido a jusante do compressor 2 e do resfriador 3 via uma entrada 6hp de fluido de alta pressão a resfriar e uma saída Shp desse fluido assim resfriado, uma válvula de descompressão sendo disposta a jusante dessa saída shp e a montante do evaporador 4.

More precisely, circuit 1 comprises:

1. - a low pressure BP line designed to convey the refrigerant fluid between the evaporator 4 and the compressor 2, through exchanger E via a 6bp low pressure fluid inlet to be reheated and a sbp outlet of that fluid so reheated, and
2. - an HP high pressure line designed to convey that same fluid downstream of compressor 2 and chiller 3 via a 6hp inlet of high pressure fluid to be cooled and an Shp outlet of that fluid so cooled, a decompression valve being arranged downstream of this shp outlet and upstream of the evaporator 4.

The E exchanger is a countercurrent coaxial type, and it is designed to cool the fluid coming from the HP line by conduction in contact with the same fluid coming from the BP line which is reheated in exchange. For this and as illustrated in the example of figure 3, this exchanger E consists of a radially internal metallic tube 10 which delimits in its internal space an internal channel 11 for the fluid coming from the BP line and which is inserted axially in the inside of a radially external tube 20 also metallic which delimits with the tube 20 an external channel 21 of annular cross section for the fluid coming from the HP line.

As illustrated in figures 2 and 3, a spacing insertion element 30 that forms a crosspiece according to the first example of the invention, which is intended to optimize the thermal transfer between HP and BP fluids by generating turbulence within the external channel 21 , it is mounted sliding between the tubes 10 and 20 and in contact with the latter, being for this purpose arranged in recoil according to an adjustable axial distance from the connection end 22 of the external tube 20. In this way, the end zone of the external channel 21 which is completely free of access - due to the fact that it lacks an insert 30 - can be easily connected to a bypass 40, such as a filling valve body or a support pipe for a depression sensor, for example example by a connection hole 23 formed in the outer tube 20.

The insertion element 30 is formed by several ribs 31 connected circumferentially at their respective bases by a cylindrical wall 32 that fits the wall of the inner tube 19, the total radial height of the wall 32 and each rib 31 being substantially equal to that of the channel external (with the exception of the mounting clearance to allow the insertion element 30 to slide).

As shown in figures 4 and 5, a spacer insert 130 according to the second example of the invention is formed by a spiral rib that fits at the same time to the inner tube 10 and the outer tube 20 of the exchanger E extending to this in a helix around the latter (according to a constant step in this realization example, it being specified that this step could vary in the axial direction and that the spiral could be discontinuous along the external channel 21).

As previously indicated, it will be noted that the insertion element 30, 130 allows at the same time to improve the thermal transfer between HP and BP fluids and to serve as a radial crosspiece between these tubes to ensure their concentricity, notably in curved or arched segments of the E exchanger .

In the embodiment of figure 6, which includes, for example, the insertion element 30, 130 of figures 2 or 4, the inner tube 10 has a surplus portion 12 that axially exceeds the end 22 of the tube 20, being integral with the latter and constituting the latter the connection piping from the internal channel 11 of the exchanger E to the BP line of the air conditioning circuit 1. That end 22 of the tube 20 can be joined to the portion 12 of the tube 10 by a reduction of diameter applied to it by knurling, followed by a circumferential fixation of the end 22 with the diameter thus reduced in that portion of the tube 12 preferably by welding or brazing (it being necessary that other methods such as magnetic forming or even a glue can be used).

In the embodiment of figure 7, which also includes, for example, the insertion element 30, 130 of figures 2 or 4, the tube 120 is attached to the tube 110 by crimping with prior threading between the respective ends 112 and 122 of the tubes 110 and 120 of an end of a flexible tube 50 connecting to circuit 1, that tube 50 being in this example mounted in axial stop against a collar 113 of the tube 110 (the deformations of the respective ends 112 and 122 of the tubes 110 and 120 were schematically represented) due to this setting in contact with the tube 50).

It will be noted that the two embodiments of figures 6 and 7 have the advantage of allowing the connection of the corresponding end of the exchanger E to the rest of the air conditioning circuit 1 without requiring a welding or brazing of one or more female connector (s) ) of which the massive structure and the pre-machining required are known drawbacks for this connection due to their weight and the overall additional cost of assembly that they represent for the E changer.

Claims (12)

Internal heat exchanger (E) of coaxial tubular type for a motor vehicle air conditioning circuit (1) comprising two portions of low and high pressure (BP and HP) traversed by a refrigerant, the exchanger defining at least one channel radially inner (11) preferably for the low pressure fluid inside an inner tube (10, 11) and a radially outer channel (21) preferably for the high pressure fluid formed between that inner tube and an outer tube (20, 120), characterized by the fact that spacing means (30, 130) of thermal conductivity lower than that of the inner and outer tubes are mounted mobile at least in translation between these two tubes and extend in a part only the length of the external channel, at least one area of the latter devoid of these means being destined to be connected to a branch (40), such as a valve body or a sensor support pipe, through a connection hole (2 3) formed in the external tube perpendicularly to that zone. Exchanger (E) according to claim 1, characterized by the fact that said spacing means (30, 130) are mounted in contact with the inner (10, 110) and outer (20, 120) tubes in order to serve of radial crossbeams between these tubes to ensure their concentricity. Exchanger (E) according to claim 2, of a type that has at least one curved or arched segment, characterized by the fact that said spacing means (30, 130) are inserted at least in the location of that segment (s) ( s). Exchanger (E) according to any one of claims 1 to 3, characterized in that said spacing means (30, 130) extend axially in a continuous or discontinuous manner over said part of the external channel (21) ending at recoil of at least one connecting end (22, 122) of the outer tube (20, 120). Exchanger (E) according to claim 4, characterized in that said spacing means (30) are formed by several longitudinal ribs (31) connected circumferentially between their respective bases by a substantially cylindrical wall (32) adjust to the inner tube (10, 110), in such a way that the total radial height of that wall and each rib is substantially equal to that of the outer channel (21). Exchanger (E) according to claim 4, characterized in that said spacing means (130) are formed by at least one spiral rib suitable to fit the inner tube (10, 110) extending to it in a helix around the latter according to a constant or variable step. Exchanger (E) according to any one of claims 1 to 6, characterized by the fact that it incorporates said branch (40) perpendicularly to said external channel region (21) devoid of said spacing means (30, 130) that it is located in the proximity of an end (22, 122) of the external tube (20, 120), this derivation being formed by a pipe of connection of the exchanger destined to convey the fluid that comes from or in the direction of the external channel. Exchanger (E) according to claim 7, characterized in that the inner tube (10) has at least one of its ends an excess portion (12) that axially exceeds the corresponding end (22) of the outer tube (20 ) being solidary of that last end and that forms by itself another pipe of connection of the exchanger destined to convey the fluid that comes from or in the direction of or of each internal channel (11). Exchanger (E) according to claim 8, characterized in that said end (22) of the outer tube (20) is joined to the inner tube (10) by a reduction in the diameter of that end for example obtained by knurling, followed by a circumferential fixation of that end to this inner tube, for example performed by welding, brazing, magnetic forming or by gluing. Changer (E) according to claim 7, characterized by the fact that at least one of its ends (122), the outer tube (120) is joined to the inner tube (110) by crimping with prior threading between the ends (112 and 122) of these tubes (110 and 120) from one end of a flexible tube (50) connecting to the air conditioning circuit (1), which tube is optionally mounted on an axial stop against a collar (113) of the tube internal. Changer (E) according to any one of claims 7 to 10, characterized in that it is devoid of any high pressure / low pressure female connector for the connection of the internal (s) (11) and external (s) channels (21) to the air conditioning circuit (1). Air conditioning circuit (1) for the motor vehicle, characterized by the fact that it comprises an internal heat exchanger (E) as defined in any of the preceding claims which is preferably connected to that circuit without a high pressure / low pressure female connector .

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