EP1992892A1 - Accumulator for an air-conditioning circuit of the type with an internal heat exchanger and circuit including same - Google Patents

Abstract

The present invention relates to an accumulator for an air conditioning circuit comprising an internal heat exchanger, and such a circuit incorporating this accumulator, in particular for a motor vehicle.

An accumulator (101) according to the invention incorporates a baffle (105), a desiccant system (113) and an internal heat exchanger (110) which comprises two pipes of high and low pressure respectively (112 and 117) intended to be traversed by a refrigerant circuit and arranged around a longitudinal axis of symmetry (106) of the accumulator.

According to the invention, the exchanger comprises a stack of fins (111) for cooling the fluid flowing in the high-pressure pipe via the fluid at low pressure contained in the accumulator, these fins being stacked along the accumulator substantially perpendicular to this axis and supporting the desiccant system and at least the high pressure pipe around said axis.

Description

The present invention relates to an accumulator for an air conditioning circuit comprising an internal heat exchanger, and such a circuit incorporating this accumulator, in particular for a motor vehicle. The invention applies in particular but not exclusively to an air conditioning circuit using carbon dioxide as a refrigerant.

In certain air conditioning circuits for motor vehicles, especially those using carbon dioxide as a refrigerant, it is necessary to perform an exchange or heat transfer between the fluid of the high pressure portion of the circuit that is to be cooled and the same fluid from the low pressure portion of this circuit which serves as a cold source and which is heated in exchange, to improve the efficiency of the circuit. To this end, an internal heat exchanger is used, because it does not seek an exchange with the outside air of the vehicle or with the air of the passenger compartment.

In known manner, such an air conditioning circuit with an internal heat exchanger also comprises in particular a compressor, a cooler or condenser from which the high pressure portion to be cooled, an evaporator from which the low pressure portion is heated in the exchanger and a accumulator which is mounted between the evaporator and the compressor and which is essentially designed to separate the liquid and gaseous phase of the refrigerant by preventing the return of the latter in the liquid state to the compressor, via a deflector that includes the accumulator in its upper part.

This accumulator is usually provided with a desiccant system in its lower part, to protect the various components of the air conditioning system from moisture. This desiccant system generally consists of a relatively bulky bag or cartridge which contains a desiccant salt and which is manually raised to bottom of the accumulator via a fastening means, such as a clamp, able to keep the desiccant system in place in use.

He is known, by the documents US-B-6,463,757 and US-B-6,523,365 , to integrate in such an accumulator an internal heat exchanger in which the high pressure line for the refrigerant is formed of a coil which is arranged helically around the inner face of the side wall of the accumulator and which n ' is not in contact with the fluid accumulated in the liquid state at the bottom of this accumulator. This coil makes it possible in particular to increase the residence time of the fluid in the exchanger and therefore the efficiency of the latter.

A major disadvantage of the accumulators described in these two documents resides in particular in the length and large size of the coil used for the high pressure pipe, as well as in the constraint inherent in the manual fixing of the aforementioned desiccant system in a small space located at the bottom. of the accumulator.

The document US-B-6,681,597 also teaches the integration of an internal heat exchanger into an accumulator for an air conditioning circuit, with a high-pressure "U" pipe which is coplanarly housed inside a low-pressure "J" pipe and which is provided with a stack of fins between the two wings of the "U", so as to improve the efficiency of the heat exchange by increasing the exchange surface, without increasing the residence time of the fluid in the exchanger. Note that the latter document does not mention the mounting of a desiccant system in the accumulator, and that the reduced height between the high pressure pipe "U" and the bottom of the accumulator greatly complicates such a mounting.

An object of the present invention is to provide an accumulator for an air conditioning circuit intended to be mounted between an evaporator and a compressor of said circuit, this accumulator incorporating a baffle, a desiccant system and an internal heat exchanger which comprises two pipes of respectively high and low pressure intended to be traversed by a refrigerant of said circuit and arranged around a longitudinal axis of symmetry of the accumulator, which allows to overcome the aforementioned drawbacks.

For this purpose, an accumulator according to the invention is such that said exchanger further comprises a stack of fins for cooling the fluid flowing in said high pressure pipe via the low-pressure fluid contained in the accumulator, these fins being stacked on the along the accumulator substantially perpendicular to said axis and supporting, on the one hand, said desiccant system and, secondly, at least said high pressure pipe around said axis (which is thus mounted in contact with the fins).

It will be noted that this incorporation of the desiccant system into the internal heat exchanger makes it possible to dispense with the means for fastening this system to the bottom of the accumulator and to mount said system in a simple and possibly automated manner by keeping it in position at the same time. inside the accumulator, unlike the manual mounting required in known accumulators.

It will also be noted that this stack of fins also makes it possible to improve the exchange surface in this exchanger, so as to optimize the cooling of the fluid flowing in the high-pressure pipe. These fins are made of a material of high thermal conductivity, preferably a metallic material such as aluminum, without limitation.

According to another characteristic of the invention, said stack may have an axial channel substantially centered on said axis, advantageously obtained via a piercing of orifices opposite in the fins, in which channel is mounted a drying container containing a desiccant ( this container may be formed of a conduit in which is housed a bag or a cartridge containing the desiccant, or may be simply formed of such a bag, for example), this container having a side wall in fluid communication with the internal space of the accumulator, for example via perforations formed in this wall. In this case, the stack of fins thus supports the desiccant system substantially centered on said axis.

It will be noted that this desiccation container thus equipped, which delimits the desiccant system according to the invention, can thus be indifferently a bag or a duct of cylindrical geometry (advantageously of circular section) or prismatic (for example of square section).

According to a preferred embodiment of the invention, said desiccation container is formed of a duct mounted integral with said deflector, which may in this case advantageously be formed in one piece with the latter.

The "desiccant" deflector thus obtained makes it possible to group together in one and the same component the two main functions of an accumulator, thereby eliminating an article reference and further simplifying the assembly of the desiccant system inside the accumulator. which reduces the overall cost of manufacturing the accumulator.

It should be noted, however, that the desiccant system of an accumulator according to the present invention could also be dissociated (i.e. separately mounted) from the deflector equipping it in its upper part.

According to another characteristic of the invention, said stack may have at least two axial channels which are formed through said fins and about said axis being two by two interconnected by a bend, and in which is mounted the high pressure line in contact with these fins.

Advantageously, this high-pressure pipe may have a lower bend which is adjacent to a bottom wall of the accumulator and which is located immediately above a lower bend of the low-pressure pipe, so that part of the high-pressure pipe is located at the bottom of the accumulator and is thus able to bathe in the low-pressure liquid fluid accumulated at the bottom of the accumulator, in order to optimize the aforementioned cooling of the fluid in the high-pressure pipe.

Also advantageously, said low pressure pipe can be accommodated along an external lateral face of said stack, for example in two axial housings symmetrical to each other with respect to said axis and formed in this external face.

Note that this configuration of the internal heat exchanger according to the invention advantageously has a small footprint inside the accumulator, in particular due to the relatively short length of the high pressure line (unlike the coils of the prior art mentioned above) and that the independence between the two high and low pressure lines makes it possible to dispense with any soldering or soldering connection unit, for example.

According to a first exemplary embodiment of the invention, said high-pressure pipe may have substantially a U-tube shape, the low-pressure pipe being advantageously bent substantially in the form of a "J" pipe and then extending in a plane substantially perpendicular to that containing the high pressure pipeline.

According to a second exemplary embodiment of the invention, the high-pressure pipe may have substantially a first U-shaped tubular section extending non-coplanarly by a second inverted U-shaped tubular section, which is again extended in a non-coplanar manner by a third U-shaped tubular section whose base is for example overlapped by that of the first section, the low pressure pipe can then also be bent substantially J-shaped extending for example in a plane substantially parallel to that containing portions; inlet and outlet of the high pressure pipeline.

Furthermore, this low pressure pipe substantially shaped "J" may further comprise in a known manner one or more holes, so that the oil contained in the accumulator can return to the compressor and thus circulate in the air conditioning circuit .

It will be noted, however, that the high-pressure line integrated in the accumulator according to the invention could have a geometry other than those in one or more U-shaped tubular sections mentioned above, may for example be constituted by a straight tube or zigzag, non-limiting.

Advantageously, said fins of said stack may have, in whole or in part, an embossed surface, microreliefs and / or axially offset or facing orifices forming ventilation flaps, so as to improve the natural convection of said fluid. at low pressure through the stack and thus to further optimize the heat exchange for cooling the fluid of the high pressure line.

An air conditioning circuit according to the invention is in particular intended to equip a motor vehicle and comprises an accumulator which is mounted between an evaporator and a compressor of said circuit and which incorporates an internal heat exchanger. According to the invention, this circuit is characterized in that this accumulator is as defined above.

• la figure 1 est une vue schématique en coupe, dans un plan longitudinal médian, d'un accumulateur selon un premier exemple de l'invention intégrant un déflecteur, un échangeur thermique interne à ailettes partiellement illustré et un logement pour un système dessicatif,
• la figure 2 est une vue schématique en coupe dans un plan longitudinal médian d'un ensemble déflecteur - système dessicatif selon un exemple préférentiel de l'invention pour l'accumulateur de la figure 1,
• la figure 3 est une vue de dessus des ailettes de l'échangeur selon la figure 1 selon un mode de réalisation de l'invention,
• la figure 4 est une vue de dessus des ailettes de l'échangeur selon la figure 1 selon une variante de la figure 3,
• la figure 5 est une vue de dessus des ailettes de l'échangeur selon la figure 1 selon une autre variante de la figure 3,
• la figure 6 est une vue en coupe selon le plan VI-VI de la figure 7 d'un accumulateur selon un second exemple de l'invention intégrant également un déflecteur, un échangeur thermique interne à ailettes et un système dessicatif,
• la figure 7 est une vue en coupe selon le plan VII-VII de la figure 6 du même accumulateur selon ce second exemple de l'invention,
• la figure 8 est une vue en perspective de l'accumulateur selon les figures 6 et 7,
• les figures 9 et 10 sont des vues en coupe correspondant respectivement aux figures 6 et 7 et illustrant uniquement le montage de la canalisation haute pression de l'échangeur dans les ailettes de ce dernier, et
• la figure 11 est une vue en perspective illustrant le montage de cette canalisation haute pression dans ces ailettes, conformément aux figures 9 et 10.

Other characteristics, advantages and details of the present invention will emerge on reading the following description of an exemplary embodiment of the invention, given by way of nonlimiting illustration, said description being made with reference to the accompanying drawings, among which :

• the figure 1 is a diagrammatic sectional view, in a median longitudinal plane, of an accumulator according to a first example of the invention incorporating a deflector, an internally illustrated fin heat exchanger and a housing for a desiccant system,
• the figure 2 is a schematic sectional view in a median longitudinal plane of a deflector assembly - desiccant system according to a preferred example of the invention for the accumulator of the figure 1 ,
• the figure 3 is a top view of the fins of the exchanger according to the figure 1 according to one embodiment of the invention,
• the figure 4 is a top view of the fins of the exchanger according to the figure 1 according to a variant of the figure 3 ,
• the figure 5 is a top view of the fins of the exchanger according to the figure 1 according to another variant of the figure 3 ,
• the figure 6 is a sectional view according to plane VI-VI of the figure 7 an accumulator according to a second example of the invention also incorporating a deflector, an internal heat exchanger with fins and a desiccant system,
• the figure 7 is a sectional view along plane VII-VII of the figure 6 of the same accumulator according to this second example of the invention,
• the figure 8 is a perspective view of the accumulator according to Figures 6 and 7 ,
• the Figures 9 and 10 are sectional views respectively corresponding to Figures 6 and 7 and illustrating only the assembly of the high pressure line of the exchanger in the fins of the latter, and
• the figure 11 is a perspective view illustrating the mounting of this high pressure pipe in these fins, in accordance with Figures 9 and 10 .

The accumulator 1 according to the first example of the figure 1 is intended to be mounted between an evaporator and a compressor of an air conditioning circuit using in particular carbon dioxide as a refrigerant. This accumulator 1 essentially comprises a reservoir 2 which is delimited in this example by a cylindrical side wall ending in a concave bottom, for example substantially in the form of a hemispherical cap (this bottom may nevertheless have any other geometry, such as a conical shape or same flat, non-limiting) and which is closed in its upper part by a closure cap 3 provided with orifices 4 connecting an internal heat exchanger 10 which is integrated with the accumulator 1. It will be noted that no It would not be outside the scope of the invention to provide a second closure plug at the lower end of the accumulator 1.

More precisely, the accumulator 1 of the figure 1 comprises in known manner a deflector 5 in its upper part which is located below the plug 3 adjacent to the latter, and which is designed to separate the liquid and gaseous phase of the refrigerant from the refrigerant circuit. air conditioning by preventing the return of this fluid in the liquid state to the compressor.

• un système dessicatif 13 monté centré sur l'axe 6, via un canal central 14 qui est obtenu par des perforations en regard formées dans les ailettes 11 et dans lequel est monté un conduit de dessication 13a perforé contenant un agent dessicatif (non illustré, e.g. logé dans un sac ou une cartouche, ce conduit 13a étant visible à la figure 2) et communiquant avec l'espace interne de l'accumulateur 1, et
• la canalisation haute pression 12 de l'échangeur 10 formée d'un tube en U dans l'exemple de la figure 1, dont les ailes 12a et 12b définissant des portions d'entrée et de sortie du fluide haute pression (voir flèches A et B pour l'entrée et la sortie de fluide) sont respectivement logées dans deux canaux latéraux 15 et 16 axiaux formés à travers les ailettes 11 et symétriques l'un de l'autre par rapport à l'axe 6 (et donc au canal central 14 recevant le conduit 13a) et dont le coude inférieur 12c est agencé à proximité immédiate du fond du réservoir 2, de telle sorte qu'une partie inférieure de la canalisation haute pression 12 baigne dans le fluide liquide basse pression accumulé au fond de l'accumulateur 1.

The internal heat exchanger 10 comprises fins 11 stacked along the tank 2 perpendicular to its longitudinal axis of symmetry 6 and intended to cool the refrigerant circulating in a high pressure pipe 12 of the exchanger 10 via the low pressure fluid contained in the accumulator 1 and, according to the invention, these fins 11 support at the same time:

• a desiccant system 13 mounted centered on the axis 6, via a central channel 14 which is obtained by facing perforations formed in the fins 11 and in which is mounted a perforated drying duct 13a containing a desiccant (not shown, eg housed in a bag or a cartridge, this conduit 13a being visible at the figure 2 ) and communicating with the internal space of the accumulator 1, and
• the high pressure line 12 of the exchanger 10 formed of a U-shaped tube in the example of the figure 1 , whose wings 12a and 12b defining inlet and outlet portions of the high pressure fluid (see arrows A and B for the inlet and the fluid outlet) are respectively housed in two axial lateral channels 15 and 16 formed through the fins 11 and symmetrical to each other with respect to the axis 6 (and therefore to the central channel 14 receiving the conduit 13a) and whose lower bend 12c is arranged in the immediate vicinity of the bottom of the tank 2, such so that a lower portion of the high pressure line 12 is immersed in the low pressure liquid fluid accumulated at the bottom of the accumulator 1.

Is also partially illustrated at the figure 1 a low pressure line 17 of the exchanger 10 formed of a substantially "J" bent tube, which is mounted in a plane substantially perpendicular to that containing the high pressure line 12 and whose lower elbow 17a overlaps the bottom one; of Line 12 (are visible at figure 1 the upper outlet portion of the low pressure fluid, identified by the arrow C, and the lower elbow 17a).

Maintaining the deflector 5 in the accumulator 1 can be ensured by a wedging made to choose against one of the pipes 12 and 17 through the cap 3, against the inner face of the wall of the tank 2, against the stack of fins 11 or even against this plug 3.

The deflector assembly 5 - desiccant system 13 which is illustrated preferentially only at figure 2 is characterized in that the drying duct 13a is formed integrally with the deflector 5, being fixed to the latter in a centered manner (the deflector 5 is conventionally flattened dome or cup returned). It will be noted that this monoblock structure advantageously makes it possible to avoid the manual fixing (eg by clamping) of the desiccant system to the bottom of the accumulator 1 and thus to reduce the overall manufacturing cost of the latter.

The Figures 3 to 5 illustrate various embodiments of the fins 11, 11 ', 11 "used to form the stack supporting the desiccant system 13 and the high pressure line 12, in which we can see the central channel 14 for the desiccation line 13a and the two lateral channels 15 and 16 for the high-pressure pipe 12, as well as variable shapes for these fins 11, 11 ', 11 "which can be for example substantially rectangular ( Figures 3 and 4 ) or substantially oval with two semicircular portions respectively surrounding the lateral channels 15 and 16 which are interconnected by a median constriction around the central channel 14 ( figure 5 ).

The accumulator 101 according to the second example of the invention, which is illustrated in FIGS. Figures 6 and 7 and whose internal heat exchanger 110 (housed inside a reservoir 102 closed by the plug 103) is visible in various aspects to Figures 8 to 11 , is essentially different from that of the figure 1 in that the high pressure line 112 of this exchanger 110 does not have a U-shaped tube geometry but, as is notably visible in FIGS. figures 8 and 11 has, from its inlet (arrow D) at its fluid outlet (arrow E), a first U-shaped tubular section 112a extending non-coplanarly by a second inverted U-shaped tubular section 112b, which again extends in a non-coplanar manner by a third tubular section 112c U whose base 112d is overlapped downwardly by the elbow 112e of the first section 112a. These sections 112a, 112b, 112c may be provided with assembly sleeves, such as the sleeve 112f illustrated in a non-limiting manner to the figure 6 .

Like the figure 1 these sections 112a, 112b, 112c are received in the stack of fins 111 via axial alignments of perforations formed through these fins 111 (four alignments in the example of Figures 6 to 11 , instead of the two alignments 15 and 16 of the figure 1 ). Note that one could provide a geometry and a different number of such perforation alignments in the fins 111 without departing from the scope of the invention.

As for the low pressure pipe 117, it is formed of a bent tube in "J" (as in the figure 1 ) and extends according to this example in a plane substantially parallel to that containing the inlet and outlet portions of the high pressure pipe 112, overlapping from below the pipe 112 via its lower elbow 117a. It will be noted, however, that the low pressure pipe 117 could be arranged differently with respect to the pipe 112.

As illustrated in figures 8 and 11 , the low pressure line 117 according to this second example of the invention is housed along an external lateral face 111a of the stack of fins 111, advantageously by means of two axial housings 115 and 116 symmetrical one of the other relative to the longitudinal axis of symmetry 106 of the accumulator 101 and formed in said outer face 111a via a pair of diametrically opposed half-circle notches 111b which are formed in each fin 111 (which is present in this example a substantially circular contour), for receiving the low pressure line 117 within the accumulator 101.

As for the first example of the invention illustrated in figure 1 it will be noted that this accumulator 101 according to the invention advantageously integrates with reduced compactness, thanks to the stack of perforated fins 111 that it contains, both the functions of accumulator (via the deflector 105 in its upper part ), moisture capture (via the perforated duct drying system 113a 113a supported axially in the center of this stack via a central channel 114 thereof) and internal heat exchanger (via in particular the high pressure pipe 112 also supported by this stack on both sides of the desiccant system 113 and arranged to dive sufficiently into the low pressure liquid fluid accumulated at the bottom of the accumulator 101).

Claims (12)

An accumulator (1, 101) for an air conditioning circuit for mounting between an evaporator and a compressor of said circuit, said accumulator incorporating a baffle (5, 105), a desiccant system (13, 113) and an internal heat exchanger (10, 110) which comprises two pipes respectively of high and low pressure (12, 112 and 17, 117) intended to be traversed by a refrigerant of said circuit and arranged around a longitudinal axis of symmetry (6, 106) of the accumulator , characterized in that said exchanger further comprises a stack of fins (11, 11 ', 11 ", 111) for cooling the fluid flowing in said high-pressure pipe via the low-pressure fluid contained in the accumulator, these fins being stacked along the accumulator substantially perpendicular to said axis and supporting, on the one hand, said desiccant system and, on the other hand, at least said high pressure pipe around said axis. Accumulator (1, 101) according to claim 1, characterized in that said stack (11, 11 ', 11 ", 111) has an axial channel (14, 114) substantially centered on said axis (6, 106) in which is mounted a desiccant container (13a, 113a) containing a desiccant, for example of the type housed in a bag or a cartridge, said container having a side wall in fluid communication with the internal space of the accumulator, for example via perforations formed in this wall. Accumulator (1) according to claim 2, characterized in that said desiccant container (13a) is formed of a duct mounted integral with said deflector (5). Accumulator (1, 101) according to one of the preceding claims, characterized in that said stack (11, 11 ', 11 ", 111) has at least two axial channels (15 and 16) which are formed through said fins and around said axis (6, 106) being connected in pairs them by a bend, and in which is mounted said high pressure line (12, 112). Accumulator (1, 101) according to claim 4, characterized in that said high pressure pipe (12, 112) has a lower bend (12c, 112e) which is adjacent to a bottom wall of the accumulator and is located immediately above a lower bend (17a, 117a) of the low pressure line, such that part of said high pressure line is immersed in the low pressure liquid fluid accumulated at the bottom of the accumulator. Accumulator (1) according to claim 5, characterized in that said high pressure pipe (12) has substantially a U-tube shape. Accumulator (101) according to claim 5, characterized in that said high pressure pipe (112) has substantially a first U-shaped tubular section (112a) extending non-coplanarly by a second inverted U-shaped tubular section (112b), which is extended again non-coplanar manner by a third U-shaped tubular section (112c) whose base (112d) is for example overlapped by that (112e) of said first section. Accumulator (101) according to one of the preceding claims, characterized in that said low pressure pipe (117) is housed along an external lateral face (111a) of said stack (11, 11 ', 11 ", 111), for example in two axial housings (115 and 116) symmetrical to each other with respect to said axis (106) and formed in this outer face. Accumulator (1) according to claims 6 and 8, characterized in that said low pressure pipe (17) is bent substantially in the form of a "J" tube and extends in a plane substantially perpendicular to that containing said high pressure pipe ( 12). Accumulator (101) according to claims 7 and 8, characterized in that said low pressure pipe (117) is bent substantially in the form of a "J" tube and extends in a plane substantially parallel to that containing inlet and outlet portions of said high pressure line (112). Accumulator (1, 101) according to one of the preceding claims, characterized in that said fins (11, 11 ', 11 ", 111) have, in whole or in part, an embossed surface, microreliefs and / or axially offset orifices. or facing forming aeration flaps, so as to improve the natural convection of said fluid at low pressure through said stack. An air conditioning circuit in particular for a motor vehicle comprising an accumulator (1, 101) which is mounted between an evaporator and a compressor of said circuit and which incorporates an internal heat exchanger (10, 110), characterized in that said accumulator is as defined according to one of the preceding claims.

Images