FR2802291A1 - AIR CONDITIONING CIRCUIT, PARTICULARLY FOR MOTOR VEHICLE - Google Patents

Abstract

An air conditioning circuit comprises a compressor (10), a condenser (12), an expansion valve (14) and an evaporator (16) suitable for being traversed by a refrigerant. The condenser (12) comprises a first outlet (26) connected to a first branch (28) of an internal heat exchanger (30) and a second outlet (32) connected through a second regulator (34) to a second branch (36) of said internal heat exchanger. The first branch (28) is connected to the regulator (14) of the circuit, while the second branch (36) is connected upstream of the compressor (10). The condenser (12), the internal heat exchanger (30) and the second expander (34) are arranged in the form of a unitary module (20) suitable for being installed in the circuit.

Description

Air conditioning circuit, in particular for a motor vehicle The invention

  concerns an air conditioning circuit, in particular

for motor vehicle.

  A conventional air conditioning circuit is traversed by a refrigerant, generally a fluorinated compound, which is present in two different phases, namely a gas phase and a liquid phase. Such a circuit essentially comprises a compressor, a condenser, a pressure reducer and an evaporator traversed, in this order, by the refrigerant fluid. The refrigerant in the gas phase is compressed by the compressor, then transformed into the liquid phase in the condenser which is swept by an air flow, then expanded at low pressure by the regulator and, finally, transformed into the vapor phase in the evaporator , which is traversed by an air flow, and so on. In the evaporator, the refrigerant absorbs heat from an air flow which is thus cooled to be sent for example into the living room

of a motor vehicle.

  There are also known air conditioning circuits which function-

  nent with natural refrigerants, such as carbon dioxide (CO2), according to a so-called "supercritical" cycle, since the refrigerant is present in only one phase, namely a gas phase, and not not in two phases as in the case of the circuits of

conventional air conditioning.

  An air conditioning circuit operating according to a supercritical cycle essentially comprises a compressor, a

  gas cooler (also called "gas cooler"), an exchanger

  internal heat sink, regulator, evaporator and accumulator. Thus, the conventional condenser is replaced by a gas cooler which releases heat under a

variable high pressure.

  In a conventional air conditioning circuit, there is provision

  usually a bottle placed between the compress

  sor and the condenser, i.e. an accumulator placed between the evaporator and the compressor, so that it is not possible to exercise control of the sub-cooling of the

  refrigerant at the outlet of the condenser.

  To overcome this drawback, various techniques for controlling and improving sub-cooling have been

proposed.

  In a first solution, sub-cooling is forced by the use of a third heat exchanger placed after the bottle. This forms a condenser, bottle and sub-cooling module which can be

grouped in a single module.

  According to a second solution, subcooling is forced by the use of an expansion member (on command

  internal or external) placed between the bottle and the

  sister. In a third solution, an internal heat exchanger is used which cools the hot liquid at the outlet of the

  condenser by fresh gases at the outlet of the evaporator.

  The second solution is particularly suitable for operating according to a supercritical cycle with a fluid

  natural refrigerant, in particular carbon dioxide.

  All of these known air conditioning circuits have the drawback of requiring a large number of connections.

  between the different components of the circuit.

  The object of the invention is in particular to overcome such a drawback

  deny. To this end, it offers an air conditioning circuit of the type defined in the introduction, in which the condenser comprises a first outlet connected to a first branch of an internal heat exchanger and a second outlet connected through a second regulator to a second branch of the internal heat exchanger, in which the first branch of the internal heat exchanger is connected to the expansion valve of the circuit, while the second branch of the internal heat exchanger is connected upstream of the compressor, and in which the condenser, the internal heat exchanger and the second pressure reducer are arranged in the form of a unitary module suitable for being installed in the circuit. The invention thus makes it possible to integrate, in a unitary module,

  the condenser, an internal exchanger and a second regulator.

  The result in particular is a reduction in the number of connections, a reduction in the total length of the

ducts and modularity.

  In the circuit of the invention, the refrigerant is thus divided, at the outlet of the condenser, into two parts, a first part which passes through the second expander and which cools a second part of the refrigerant. The first part is used for the super-cooling of the second part, which is directed towards the regulator. This first part is returned directly to the compressor suction. According to another characteristic of the invention, the module

  unit includes only one input and two outputs.

  Advantageously, the input of the unitary module is adapted to be connected to a line coming from the compressor, while a first output of the unitary module is adapted to be connected to a line leading to the regulator, and that a second output of the unitary module is suitable for being connected to a

  bypass line leading to the compressor inlet.

  In a first embodiment of the invention, the second regulator is interposed directly between the second outlet of the condenser and the second branch of

the internal heat exchanger.

  In this case, it is advantageous for the circuit to further comprise an accumulator placed between the unitary module and the pressure reducer and / or a bottle placed between the evaporator and

the compressor.

  In a second embodiment of the invention, the unitary module further comprises an accumulator interposed between the second regulator and the second branch of

the heat exchanger.

  The second regulator can be either of the command type

  external, or of the thermostatic type.

  The circuit of the invention can be used with a refrigerant present in the gas phase and in the liquid phase, the

  condenser then ensuring the condensation of the refrigerated fluid

  rant. The circuit can also be used with a refrigerant present only in the gas phase, according to a supercritical cycle, the condenser then constituting a gas cooler for cooling the refrigerant. In another aspect, the invention relates to a unitary module capable of being part of an air conditioning circuit as defined above and comprising a condenser, a heat exchanger

  internal heat and a second regulator.

  In the following detailed description, made only at

  By way of example, reference is made to the appended drawings in which: - Figure 1 shows an air conditioning circuit for a motor vehicle according to a first embodiment of the invention; - Figure 2 shows an air conditioning circuit for a motor vehicle according to a second embodiment of the invention; - Figure 3 is a sectional view of a module suitable for being part of the air conditioning circuit of Figure 1; and - Figure 4 is a sectional view of a module suitable for making

  part of the air conditioning circuit of figure 2.

  The air conditioning circuit shown in Figure 1 includes

  takes, essentially, a compressor 10, a condenser 12,

  a regulator 14 and an evaporator 16, suitable for being traversed

  rus, in this order, by a coolant.

  This air conditioning circuit can be produced in the form of a conventional circuit operating with a refrigerant present in two phases, namely a phase

  gas and a liquid phase. In this case, the refrigerant

  rant in the gas phase is compressed by the compressor 10, transformed into the liquid phase in the condenser 12 (which is swept by an air flow), then expanded at low pressure by the regulator 14 and, finally, transformed into the vapor phase in the evaporator 16, which is traversed by an air flow F. This air flow is thus cooled to be sent into the passenger compartment of a motor vehicle, under the action of a

blower 18.

  Such a circuit can also operate with a refrigerated fluid.

  natural rant, such as carbon dioxide, according to a supercritical cycle, in which the refrigerant is

  always present in the gas phase. In such a case, the conden-

  seur 12 constitutes a "gas cooler" used for

  cooling of the refrigerant.

  According to the invention, the condenser 12 is part of a unitary module 20 comprising an input 22 suitable for being

  connected to a line 24 coming from the compressor 10.

  The condenser 12 comprises a first outlet 26 connected to a first branch 28 of a heat exchanger 30, called "internal heat exchanger", and a second outlet 32 connected, through a second expander 34, to a second

  branch 36 of the heat exchanger 30.

  The heat exchanger 20 is called here "internal heat exchanger" since it makes it possible to carry out a heat exchange between two parts of the same fluid,

know the refrigerant.

  The condenser 10 as well as the heat exchanger 30 and the second pressure reducer 34 form part of the unitary module 20. The latter also comprises a first outlet 38 suitable for being connected to a line 40 leading to the pressure reducer 14 and a second clean outlet 42 to be connected to a pipe of

  bypass 44 leading to the inlet of compressor 10.

  Line 40 leads to an accumulator 46, which is connected by a line 48 to the regulator 14. This regulator is connected by a line 50 to the evaporator 16. This evaporator is itself connected to a bottle 52 by a line 54. The bottle 52 is connected to the inlet of the compressor by a pipe 56. The bypass pipe 44 opens into the

  line 56 upstream of compressor 10.

  As a result, a first part of the refrigerant leaving the condenser 12 passes through the regulator 34 to cool a second part of the refrigerant. The

  first part of the refrigerant thus allows

  cool the second part which goes towards the regulator 14. This first part is thus returned directly to

compressor suction.

  The module 20 thus constitutes an assembly ready to be integrated into the circuit and comprising only one input and two

  exits. In addition, this improves the super-cooling

  ment of the part of the refrigerant which goes to the regulator 14 and which is then returned to the suction of the

  compressor via evaporator 16 and bottle 52.

  It should be noted that, in the circuit of FIG. 1, one or the other of the accumulator 46 and of the bottle 52 can be

deleted.

  In a preferred embodiment, the regulator 34 can be either an externally controlled regulator or a thermostatic regulator which opens the passage to the branch 36 of the heat exchanger 30, depending on the thermal load

of the circuit loop.

  Indeed, the need for super-cooling does not manifest itself

than at high thermal load.

  The arrangement of the module in the condenser area, which synthesizes the outside temperature and the thermal load of the circuit, allows a fairly easy thermostatic adjustment. A setting depending on the discharge temperature, or

  even the condensing temperature is sufficient.

  It should be noted that the use of a regulator with external control gives more details to the actions and leads to a

  more optimized use of the circuit.

  In addition, the connection between the heat exchanger 30 and the suction of the compressor 10 could include a pressure drop element to balance the pressures of the two.

  lines (lines 44 and 56) which converge towards the compressor

  sister. We now refer to Figure 2 which represents a

  more elaborate embodiment of the air conditioning circuit

  tion of the invention. The circuit of FIG. 2 essentially comprises the same components as those of FIG. 1 and the common components are designated by the same reference numbers. The main difference lies in the fact that the module 20 comprises an accumulator 58 interposed between the second regulator 34 and the second branch 36 of the heat exchanger.

internal heat 30.

  In addition, the accumulator 46 and the bottle 52 of the

Figure 1 have been deleted.

  This embodiment is particularly suitable for a natural refrigerant, in particular carbon dioxide.

  carbon, operating on a supercritical cycle.

  Because the high pressure line (line 24 between the compressor 10 and the condenser 12) is in the gaseous state, the reserve of refrigerant must be made

on a low pressure line.

  We thus benefit from a second low pressure line in

  parallel with a main line to place the accumu-

  tor. The arrangement of the accumulator 58, upstream of the heat exchanger 30, ensures the overheating of the gases which flow to the compressor, which avoids the risk of breakdown

compressor.

  It is also possible to arrange a bottle similar to the bottle 52 of FIG. 1, to allow its integration

in module 20.

  In the case of the circuit of FIG. 2, the regulator 34 can be either an externally controlled regulator or a regulator

internally controlled.

  When the circuit operates with a natural refrigerant, in particular carbon dioxide, the control of the loop is carried out according to the high pressure. We try to keep this high pressure at a sufficient level to be able to exchange heat correctly with the external environment. This then implies the use

  an externally controlled regulator.

  The use of a thermostatic expansion valve allows the adjustment of the high pressure upstream of the evaporator and, consequently, the use of an expansion valve with internal control

at the entrance of this evaporator.

  The unitary module 20, which integrates the condenser 12, the sample

  heat gor 30, the regulator 34 and, optionally, the accumulator 58, can be produced by means known in

  itself in the technique of heat exchangers.

  FIG. 3 represents an exemplary embodiment of a unitary module 20 suitable for forming part of the air conditioning circuit of FIG. 1. The elements common with the circuit of the

  Figure 1 are designated by the same reference numerals.

  The unitary module 20 comprises a condenser 12 formed from a multiplicity of tubes 58 which alternate with corrugated spacers 60 forming heat exchange fins. The tubes 58 open, on one side, into a manifold 62 and,

  on the other hand, in a manifold 64.

  The manifold 62 extends in a generally vertical direction and delimits internally, from the top

  below, four successive compartments 66, 68, 70 and 72.

  The inlet 22 of the condenser 12 communicates with the compartment 68. The manifold 64 extends in a general vertical direction and it delimits internally, from top to bottom, four successive compartments 74, 76, 78 and 80. The compartments 74 and 80 communicate with each other by a vertical conduit 82 which is preferably integrated in the

manifold.

  The refrigerant circulates in several passes in the tubes 58 passing successively through the compartments 68, 76, 70, 78, 72 and 80 as indicated by the arrows. Then, the refrigerant reaches compartment 74 passing through

  the conduit 82, then the compartment 66.

  Above the condenser 12 is mounted an internal heat exchanger 30 which is formed of a first branch 28 produced by a bundle of short tubes and a second branch 36 produced by a bundle of long tubes, the long tubes

  being interposed with the short tubes.

  The two branches 28 and 36 are arranged between two collectors

  teurs 84 and 86 placed respectively above the boxes

collectors 62 and 64.

  The manifold 84 comprises a side wall 88 into which the short tubes of the first branch 28 open and an internal partition 90 into which the long tubes open

  of the second branch 36. The collector 84 delimits interior

  a compartment 92 which communicates the

  compartment 66 with the first branch 28, and a compartment

  ment 94 which makes the second branch 36 communicate with the

exit 42.

  The collector 86 comprises a side wall 96 into which the short tubes of the first branch 28 open and a partition 98 into which the long tubes of the second branch 36 open. The collector 86 thus delimits two compartments: a compartment 100 which communicates with the first branch and an outlet 38, and a compartment 102 which communicates an outlet 32 of the conduit 82 with the second branch 36. For this, the collector 86 comprises, at its lower part, an inlet conduit 104 which communicates with the outlet 32 provided in conduit 82. This conduit 104 houses the

regulator 34.

  The outputs 38 and 42 of the unitary module 20 are provided

  respectively on the collector 86 and on the collector 84.

  Thus, at the outlet of the condenser, part of the refrigerated fluid

  rant circulates in the first branch 28 then leaves the module via the outlet 38 of the manifold 86. Another part of the refrigerant leaves the condenser via the outlet 32, passes through the regulator 34 and then reaches the second branch

  36 to exit via outlet 42 of collector 84.

  The unitary module 20 represented in FIG. 4 constitutes a variant of that of FIG. 3 and is suitable for being part of the circuit of FIG. 2. The elements common with those of

  FIG. 2 are designated by the same numerical references.

ques.

  The main difference compared to the module in the figure

  3 resides in the fact that the outlet 32 of the conduit 82 communicates

  that with an accumulator 58 produced in the form of a

  reservoir which extends in a generally vertical direction.

  The outlet 32 houses the regulator 34. The accumulator 58 houses a U-shaped duct 106 which has an inlet 108 placed in the upper part and an outlet 110 placed in the upper part and

  communicating with the inlet conduit 104 of the manifold.

  Thus the second branch 36 of the heat exchanger

  internal 30 is supplied via the accumulator 58.

  The circuit and the unitary module of the invention are suscep-

  tibles of many variants.

  Their application is not limited to the air conditioning of

motor vehicles.

Claims (11)

Claims   1. Air conditioning circuit of the type comprising a compressor   sor (10), a condenser (12), a pressure reducer (14) and an evaporator (16) suitable for being traversed by a coolant, characterized in that the condenser (12) comprises a first outlet (26) connected to a first branch (28) of an internal heat exchanger (30) and a second outlet (32) connected through a second expander (34) to a second branch (36) of said internal heat exchanger, in that the first branch (28) of the internal heat exchanger is connected to the expansion valve (14) of the circuit, while the second branch (36) of the internal heat exchanger is connected upstream of the compressor (10), and in this that the condenser (12), the internal heat exchanger (30) and the second pressure reducer (34) are arranged in the form of a unitary module (20)   suitable for installation in the circuit.   2. Air conditioning circuit according to claim 1,   characterized in that the unitary module (20) comprises only-   an inlet (22) and two outlets (38, 42).   3. Air conditioning circuit according to claim 2, characterized in that the input (22) of the unitary module is suitable for being connected to a line (24) coming from the compressor (10), in that a first output (38 ) of the unitary module is suitable for being connected to a line (40) leading to the regulator (14), and in that a second outlet (42) of the unitary module is suitable for being connected to a line of   bypass (44) leading to the inlet of the compressor (10).   4. Air conditioning circuit according to one of claims   1 to 3, characterized in that the second regulator (34) is interposed directly between the second outlet (32) of the condenser (12) and the second branch (36) of the heat exchanger internal heat (30).   5. Air conditioning circuit according to claim 4, characterized in that it further comprises an accumulator (46) placed between the unit module (20) and the regulator (14) and / or a bottle (58) placed between the evaporator (16) and the compressor (10).   6. Air conditioning circuit according to one of claims   1 to 3, characterized in that the unitary module (20) further comprises an accumulator (58) interposed between the second regulator (34) and the second branch (36) of the heat exchanger internal heat (30).   7. Air conditioning circuit according to one of the claims   1 to 6, characterized in that the second regulator (34) is of external control type.   8. Air conditioning circuit according to one of claims   1 to 6, characterized in that the second regulator (34) is thermostatic type.   9. Air conditioning circuit according to one of claims   1 to 8, characterized in that the refrigerant is present in the gas phase and in the liquid phase and that the   condenser (12) condenses the refrigerant.   10. Air conditioning circuit according to one of claims   1 to 8, characterized in that the refrigerant is present only in the gas phase to operate according to a supercritical cycle and that the condenser (12) constitutes a gas cooler for cooling the refrigerant. 11. Unit module suitable for being part of a circuit   air conditioning as defined in one of claims 1   to 10, and comprising a condenser (12), a heat exchanger   internal heat (30) and a second regulator (34).