ES2426247T3 - Internal heat exchanger for automobile vehicle air conditioning circuit and circuit of this type - Google Patents

Abstract

Internal heat exchanger (E) of coaxial tubular type for an air conditioning circuit (1) of a vehicle that incorporates two low and high pressure tracts (BP and HP) covered by a refrigerant fluid, the exchanger defining at least one channel radially internal (11) preferably for the low pressure fluid inside an internal tube (10, 110) and a radially external channel (21) preferably for the high pressure fluid formed between that internal tube and an external tube (20, 120) , characterized in that spacing means (30, 130) of thermal conductivity lower than that of the internal and external tubes are movably mounted at least in translation between these two tubes and run only for a part of the length of the canalexterno, destined to the less an area of the latter, devoid of these means, to be connected to a branch (40), such as a valve body or a support pipe of a sensor, by an ori interconnection fluid (23) determined in the outer tube perpendicular to that zone.

Description

Internal heat exchanger for automobile vehicle air conditioning circuit and circuit of this type

The present invention concerns an internal heat exchanger of the coaxial tubular type for an automobile vehicle air conditioning circuit and an air conditioning circuit of this type which incorporates this heat exchanger.

In certain air conditioning circuits for motor vehicles, it is necessary to perform an exchange or thermal transfer between the high pressure tract fluid of the circuit to be cooled and the same fluid coming from the low pressure tract of that circuit that serves as a cold focus and which by exchange is heated, to improve circuit performance. A heat exchanger called internal is used for this purpose, because it does not pursue an exchange with the air outside the vehicle or with the cabin air.

In a known way, a heat exchanger is of the metallic type and is connected to the corresponding conduits of the air conditioning circuit that particularly comprise hoses, through connectors mounted on each of the ends of the exchanger, which can be for example of the type of plate which, being constituted from a stack of flat tubes, performs the thermal exchange both by convection with the outside air to the exchanger and by conduction, or of the type of multitubes, which in its version more simple is a coaxial tubular countercurrent type, which then performs the heat exchange without the said convection.

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

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 inside an internal tube of the exchanger, at least one radially internal channel intended to conduct the fluid from the low pressure tract of the circuit and

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 radially between that inner tube and an outer tube in cover configuration for the exchanger, a radially external channel usually provided with longitudinal fins designed to optimize the thermal transfer between the circulating fluids through the internal (s) and external channels that are distributed by their circumference and that they can be in solidarity with the internal and / or external tubes or also inserted between these two tubes, as illustrated for example in document US-A-6 434 972.

Generally, at least one metallic female connector is then used for the end of interest of the exchanger which is joined by welding or welding at the same time on the internal and external tubes of the exchanger in order to define passageways for the fluid that communicate tightly with those internal and external channels.

Patent documents WO-A1-2007 / 013 439 and EP-A1-1 762 806 present internal heat exchangers of this type that are respectively equipped with two female connectors and with only one female connector, in these two cases through three welding or alloy welding lines at the corresponding end of the exchanger.

A major drawback of these known internal coaxial fin exchangers is that you have to give up making shunts in the outer tube perpendicular to those fins to especially attach valves or sensor-carrying pipes, or then you have to pre-machine the shaping profiles of the internal and / or external tubes in the location of the fins that they incorporate in the area of the exchanger (usually extreme) just destined to receive these shunts, which increases the manufacturing cost of the exchangers.

Another drawback of the coaxial internal exchangers that are known equipped with connectors is the relatively high weight of these connectors, which also have to be machined precisely with subsequent welding or alloy welding for their solidarity with the internal and external tubes of the exchangers, which also contributes to increasing the cost of manufacturing and assembly of the latter.

It is a purpose of the present invention to propose an internal exchanger of this type of coaxial tubular type that incorporates two low and high pressure tracts covered by a refrigerant fluid, the exchanger defining, inside an internal tube, at least one channel radially internal preferably for the low pressure fluid and a radially external channel preferably for the high pressure fluid formed between that internal tube and an external tube, exchanger that allows to overcome these drawbacks.

For this purpose, an exchanger according to the invention is such that spacing means of thermal conductivity lower than that of the internal and external tubes are mounted with the possibility of at least translation translation between these two tubes and run axially only by a part of the length of the external channel, at least one zone of the latter being allocated, devoid of these means, to be connected to a branch, such as a valve body or a support pipe of a sensor, by an interconnection hole determined in the outer tube perpendicular to that area.

It is noted that these spacing means according to the invention that play a function of spacer (i.e., separator) between these tubes thus allow, due to their thermal conductivity lower than the latter, to avoid thermal coupling in the form of thermal bridges between those two internal and external tubes. By way of example, these spacing means can be made of a metallic material (typically of thermal conductivity lower than that of aluminum in the case of tubes based on this metal) or plastic (for example, based on a polyamide).

According to another feature of the invention, these spacing means, which are intended to generate turbulence for the circulating fluid through the external channel in order to optimize the thermal transfer between high and low pressure fluids, can run axially continuously. or discontinuous on said part of the external channel ending in a delayed position with respect to at least one interconnecting end of the external tube.

According to a first embodiment of the invention, these spacing means are formed by several longitudinal ribs circumferentially related between their respective bases by a substantially cylindrical wall suitable for conforming to the inner tube, such that the total radial height of this wall and of each rib is substantially equal to 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 for fitting to the inner tube running helix around the latter according to a constant or variable pitch.

It is noted that this superimposed and sliding assembly of the spacing means between the inner and outer tubes allows them to be accurately positioned in anticipation of the or each branch to be made on the outer tube, making them slide axially out of the o of each zone of the branch to condition one or some free space (s) that allows this branch (s). Thus, the need according to the prior art of using internal or external tubes of locally machined fins in the areas destined to the shunts is totally saved, which makes it possible to reduce the cost of manufacturing the exchanger.

It is also noted that these shunts which are thus facilitated by virtue of the adjustable positioning of the spacing means may, for example, allow the connection to the exchanger of refrigerating fluid filling valve bodies, pressure sensor carrying pipes or temperature or any other radial interconnection pipe or nozzle (i.e., 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 separators between these tubes to ensure their concentric arrangement. Also advantageously, in the case where the exchanger is of the type that has at least one angled or curved section, these spacing means are preferably inserted at least in the location of this or these section (s) and, even more preferably , in most of the axial length of the external channel.

It is noted that these spacing means according to the invention thus allow to "absorb" the radii of curvature and / or curvature of the internal and external tubes of the exchanger along its length, which allows the passage section to be kept substantially constant for the fluid in the external channel and, thus, not hinder thermal exchange in the bent or curved sections.

Advantageously, an exchanger according to the invention can incorporate said branch in the perpendicular to said area of the external channel devoid of these spacing means which is located close to one end of the external tube, branch which is formed from a pipe of interconnection of the exchanger destined to conduct the fluid coming from or in the direction of the external channel.

According to another feature of the invention, the exchanger can advantageously be devoid of any high-pressure / low-pressure female connector for the connection of the internal (s) and external (s) channels to the air conditioning circuit. In other words, this exchanger is then constituted exclusively from the internal tube, the external tube and said spacing means, which do not oppose a branch that communicates with the external channel and does not have to be mechanized to allow this derivation, as explained above.

It is noted that this absence of female connector (usually of aluminum) allows to significantly reduce the mass of the exchanger according to the invention and, in addition, the overall cost of its manufacture and assembly which, in the past, is I was taxed with the machining operations of the or of each connector.

It will also be noted that the internal and external tubes of the exchanger according to the invention that no longer have to be machined by the spacing profiles can thus be used directly following their forming.

According to a first embodiment of the invention which is facilitated by the said sliding assembly of the spacing means, the inner tube has, at least one of its ends, an protruding tract axially protruding from the corresponding end of the tube. external being solidary with this last end and that determines by itself - instead of the referred female connector - another interconnection pipe of the exchanger destined to conduct the fluid coming from or in direction to or to each internal channel. In this case, this end of the outer tube can be in solidarity with the inner tube by a simple highlighting of this end obtained for example by knurling, followed by a circumferential fixation of this end on that inner tube implemented for example by welding, welding alloy, by magneto-forming (preferably in two stages, although one stage can be contemplated) or by gluing.

According to a second embodiment of the invention which is also facilitated by the said sliding assembly of the spacing means, the outer tube is connected, at one of its ends, with the inner tube by crimping with prior Plug between the respective ends of these tubes one end of a flexible hose for interconnection to the air conditioning circuit, whose hose is optionally mounted butt axially against a collar of the inner tube. It is noted that this single crimping operation then allows the two internal and external tubes of the exchanger to be attached to the adjacent hose of the air conditioning circuit.

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

Other features, advantages and details of the invention will become apparent upon reading the following description of several embodiments of the invention, given by way of illustration and not limitation, the description being made with reference to the attached drawings, of which:

Figure 1 is a schematic view of an air conditioning circuit for a motor vehicle that incorporates an internal heat exchanger according to the invention,

Figure 2 is a perspective view of a spacing insert 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 partially in perspective of an interconnecting end of an exchanger according to that first example of the invention that incorporates the insert of Figure 2,

Figure 4 is a perspective view of a spacing insert 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 partially in perspective of an interconnecting end of an exchanger according to that second example of the invention that incorporates the insert of Figure 4,

Figure 6 is a partial perspective view of an interconnecting end of an internal heat exchanger according to a first embodiment of the invention, with special reference to the examples of Figures 3 and 5 and

Figure 7 is a partial schematic view in longitudinal semi-section of an interconnecting end of an internal heat exchanger according to a second embodiment of the invention, with special reference to the examples of Figures 3 and 5.

The air conditioning circuit (1) illustrated in Figure 1 is in a known way a closed circuit or "loop" comprising, in addition to an internal heat exchanger E, several elements distributed inside the engine compartment of the vehicle, especially a compressor (2), a cooler or condenser (3) and an evaporator (4), and through which a refrigerant fluid under pressure, such as R134a or R152, circulates, without limitation. All these elements are related to each other by rigid or flexible lines constituted by rigid and / or flexible tubular tracts, which have in each of their ends airtight interconnection means.

More precisely, circuit (1) incorporates:

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 a low pressure line BP intended to conduct the refrigerant fluid between the evaporator (4) and the compressor (2), through the exchanger E through a low pressure fluid eBP inlet to be heated and a sBP outlet of this fluid so heated, and

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 a high pressure line HP intended to drive that same fluid downstream of the compressor (2) and the cooler

(3) through an eHP inlet of high pressure fluid to be cooled and an sHP outlet of this fluid thus cooled, establishing an expansion valve (5) downstream of this sHP outlet and upstream of the evaporator (4) .

The exchanger E is of the coaxial countercurrent type and is intended to cool the fluid coming from the HP line by conduction in its contact with the same fluid coming from the BP line that is heated by exchange. For this purpose and as illustrated in the example of Figure 3, this exchanger E is constituted from a radially internal metal tube (10) that delimits in its interior space an internal channel (11) for the fluid coming from the BP line and which is axially inserted inside a radially external tube (20) also metallic that 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, in sliding assembly between the tubes (10 and 20) and in contact with them, it is arranged in a delayed position according to an adjustable axial distance from the interconnecting end (22) of the tube external (20), a spacer insert (30) in separator configuration according to the first example of the invention, which is intended to optimize the thermal transfer between HP and BP fluids by generating turbulence in the external channel ( twenty-one). In this way, the end zone of the external channel (21) with total possibility of free access - due to the fact that it is devoid of the insert (30) - can be easily attached to a branch (40), such as a valve body filling or a support pipe of a pressure sensor, for example, by an interconnection hole (23) determined in the external tube (20).

The insert (30) is formed by several ribs (31) circumferentially related in their respective bases by a cylindrical wall (32) that conforms to the inner tube wall (10), the total radial height of the wall (32) being and of each rib (31) substantially equal to that of the external channel (with a margin of the order of the assembly set to allow sliding of the insert (30)).

As visible in Figures 4 and 5, a spacer insert (130) according to the second example of the invention is formed by a spiral rib that is both molded to the inner tube (10) and the outer tube (20) of the exchanger E running in propeller around the latter (according to a constant step in this exemplary embodiment, it being specified that this step could vary in axial direction and that the spiral could be discontinuous along the external channel (21)).

As indicated above, it is noted that the insert (30, 130) allows at the same time to improve the thermal transfer between HP and BP fluids and serve as a radial separator between these tubes to ensure their concentric arrangement, especially in angled or curved sections of the E. exchanger

In the embodiment of Figure 6, which integrates for example the insert (30, 130) of Figures 2 or 4, the inner tube (10) has an protruding tract (12) protruding axially from the end (22) of the tube (20) being integral with it and constituting the interconnecting pipe of the internal channel (11) of the exchanger E to the line BP of the air conditioning circuit (1). This end (22) of the tube (20) can be in solidarity with the tract (12) of the tube (10) by means of an upset that is applied by knurling, followed by a circumferential fixation of the end (22) thus stressed to that tract of tube (12) preferably by welding or alloy welding (it being specified that other procedures such as magneto-forming or even gluing are usable).

In the embodiment of Figure 7, which also integrates, for example, the insert (30, 130) of Figures 2 or 4, the tube (120) is connected to the tube (110) by crimping with a previous plug between the respective ends (112 and 122) of the tubes (110 and 120) of one end of a flexible hose (50) interconnecting to the circuit (1), this hose being mounted in this example butt axially against a collar (113) ) of the tube (110) (the deformations of the respective ends (112 and 122) of the tubes (110 and 120) due to this crimping in contact with the hose (50) have been schematically represented.

It is noted that the two embodiments of Figures 6 and 7 have the advantage of allowing the corresponding end of the exchanger E to be attached to the rest of the air conditioning circuit (1) without requiring a welding

or alloy welding of one or more female connector (s), whose solid structure and whose previous machining required, for its weight and for the overall cost of assembly that for the exchanger E represent, are known drawbacks for this union.

Claims (12)

one.

Internal heat exchanger (E) of coaxial tubular type for an air conditioning circuit (1) of a motor vehicle that incorporates two low and high pressure tracts (BP and HP) covered by a refrigerant fluid, the exchanger defining at least one channel radially internal (11) preferably for the low pressure fluid inside an internal tube (10, 110) and a radially external channel (21) preferably for the high pressure fluid formed between that internal tube and an external tube (20 , 120), characterized in that spacing means (30, 130) of thermal conductivity lower than that of the internal and external tubes are movably mounted at least in translation between these two tubes and run only for a part of the length of the external channel, at least one zone of the latter being allocated, devoid of these means, to be connected to a branch (40), such as a valve body or a support pipe of a sensor, po r an interconnection hole (23) determined in the outer tube perpendicular to that zone.

2.

Exchanger (E) according to claim 1, characterized in that said spacing means (30, 130) are mounted in contact with the inner (10, 110) and outer (20, 120) tubes in order to serve as radial separators between these tubes to ensure their concentric arrangement.

3.

Exchanger (E) according to claim 2, of a type that has at least one elbow or curved section, characterized in that said spacing means (30, 130) are inserted at least in the location of this or these section (s) .

Four.

Exchanger (E) according to any one of the preceding claims, characterized in that said spacing means (30, 130) run axially continuously or discontinuously over said part of the external channel (21) ending in a delayed position with respect to at least an interconnecting end (22, 122) of the outer tube (20, 120).

5.

Exchanger (E) according to claim 4, characterized in that said spacing means (30) are formed by several longitudinal ribs (31) circumferentially related between their respective bases by a substantially cylindrical wall (32) suitable for conforming to the inner tube (10, 110), so that the total radial height of this wall and of each rib is substantially equal to that of the external channel (21).

6.

Exchanger (E) according to claim 4, characterized in that said spacing means (130) are formed by at least one spiral rib suitable for fitting to the inner tube (10, 110) running in a helix around the latter according to a constant or variable step.

7.

Exchanger (E) according to any one of the preceding claims, characterized in that said bypass (40) is incorporated in the perpendicular to said area of the external channel (21) devoid of said spacing means (30, 130) which is found located next to one end (22, 122) of the outer tube (20, 120), bypass this is formed from an interconnection pipe of the exchanger intended to conduct the fluid coming from or in the direction of the external channel.

8.

Exchanger (E) according to claim 7, characterized in that the inner tube (10) has at least one of its ends an protruding tract (12) protruding axially from the corresponding end (22) of the outer tube (20) being solidary with this last end and that determines by itself another interconnection pipe of the exchanger destined to conduct the fluid coming from or in the direction of or to each internal channel (11).

9.

Exchanger (E) according to claim 8, characterized in that said end (22) of the outer tube (20) is in solidarity with the inner tube (10) by highlighting this end obtained for example by knurling, followed by fixing circumferential of this end on that internal tube implemented for example by welding, alloy welding, magneto-forming or gluing.

10.

Exchanger (E) according to claim 7, characterized in that, at one of at least its ends (122), the outer tube (120) is connected with the inner tube (110) by crimping with a previous plug between the respective ends (112 and 122) of these tubes (110 and 120) of one end of a flexible hose (50) interconnecting to the air conditioning circuit (1), whose hose is optionally mounted butt axially against a collar (113) of the inner tube .

eleven.

Exchanger (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 joining the internal (s) (11) and external (s) channels (21) to the air conditioning circuit (1).

12.

Air conditioning circuit (1) for motor vehicles, characterized by incorporating a

internal heat exchanger (E) as defined in any one of the preceding claims which is preferably connected to this circuit without a high pressure / low pressure female connector.