FR3056453A1 - INDIRECT INDIRECT AIR CONDITIONING CIRCUIT FOR A MOTOR VEHICLE AND METHOD OF OPERATING THE SAME - Google Patents

Abstract

The present invention relates to an indirect reversible air conditioning circuit (1) for a motor vehicle comprising: a first refrigerant fluid loop (A) comprising: a compressor (3), a first expansion device (7), a first heat exchanger (9), ○ a second expansion device (11), ○ a second heat exchanger (13), ○ a bypass branch (30) of the second expansion device (11) and the second heat exchanger ( 13), • a second heat transfer fluid loop (B), • a two-fluid heat exchanger (5) arranged jointly on the first refrigerant loop (A) downstream of the compressor (3), and on the second fluid loop coolant (B), and • an internal heat exchanger (19), allowing a heat exchange between the refrigerant at the outlet of the two-fluid heat exchanger (5) and the refrigerant from the bypass branch (30). e t / or the second heat exchanger (13), the first refrigerant loop (A) also having a branch branch (40) of the refrigerant from the second heat exchanger (13), said branch branch (40) ) directly connecting the coolant outlet of the second heat exchanger (13) to the coolant inlet of the compressor (3).

Description

(57) The present invention relates to an indirect reversible air conditioning circuit (1) for a motor vehicle comprising:

a first coolant loop (A) comprising:

O a compressor (3),

O a first expansion device (7),

O a first heat exchanger (9),

O a second expansion device (11),

O a second heat exchanger (13),

O a bypass branch (30) of the second expansion device (11) and of the second heat exchanger (13), a second loop of heat transfer fluid (B), a two-fluid heat exchanger (5) arranged jointly on the first loop coolant (A) downstream of the compressor (3), and on the second heat transfer fluid loop (B), and an internal heat exchanger (19), allowing heat exchange between the coolant leaving the dual fluid heat exchanger (5) and the refrigerant coming from the bypass branch (30) and / or the second heat exchanger (13), the first refrigerant loop (A) also comprising a branch branch (40 ) coolant from the second heat exchanger (13), said branch branch (40) directly connecting the coolant outlet of the second heat exchanger (13) to the coolant inlet of the compressor (3).

Indirect reversible air conditioning circuit of a motor vehicle and corresponding operating method

The invention relates to the field of motor vehicles and more particularly to a motor vehicle air conditioning circuit and its operating method.

Today's motor vehicles increasingly include an air conditioning circuit. Generally, in a “conventional” air conditioning circuit, a refrigerant passes successively through a compressor, a first heat exchanger, called a condenser, placed in contact with an air flow outside the motor vehicle to release heat, a device expansion valve and a second heat exchanger, called an evaporator, placed in contact with an air flow inside the motor vehicle to cool the air flow, in an operating mode called cooling mode.

There are also more complex air conditioning circuit architectures which make it possible to obtain an invertible air conditioning circuit, that is to say that it can absorb heat energy in the outside air at the level of the first heat exchanger, then called evapo-condenser, and restore it in the passenger compartment in particular by means of a third dedicated heat exchanger, in an operating mode called heat pump mode.

This is possible in particular by using an indirect air conditioning circuit. Indirect here means that the air conditioning circuit has two circulation loops of two separate fluids (such as a refrigerant and glycol water) in order to carry out the different heat exchanges.

The air conditioning circuit thus comprises a first coolant loop in which a coolant circulates, a second coolant loop in which a coolant circulates, and a two-fluid heat exchanger arranged jointly on the first coolant loop and on the second loop of heat transfer fluid, so as to allow heat exchanges between said loops.

In order to improve the performance of such an air conditioning circuit in cooling mode, it is known to equip them with an internal heat exchanger which allows the heat exchanges between the refrigerant leaving the dual-fluid heat exchanger and the fluid. refrigerant at the outlet of the evapo-condenser. However, in heat pump mode and in particular for so-called chemical coolants such as R134a or R1234YF, the presence of the internal heat exchanger is a drawback, lowering the density of the coolant before entering the compressor. from the increase in his enthalpy. This low density of the refrigerant makes its compression less efficient and it is therefore necessary to use a more powerful compressor to obtain the same pressure and therefore this decreases the performance of the air conditioning circuit.

In addition, increasing the enthalpy of the refrigerant due to the action of the internal heat exchanger in heat pump mode can cause the refrigerant to reach a high temperature which can damage the compressor.

One of the aims of the present invention is therefore to at least partially remedy the drawbacks of the prior art and to propose an improved reversible air conditioning circuit.

The present invention therefore relates to an indirect reversible air conditioning circuit for a motor vehicle comprising:

A first coolant loop in which a coolant circulates, said first coolant loop comprising in the direction of circulation of the coolant:

° a compressor, ° a first expansion device, ° a first heat exchanger, ° a second expansion device, ° a second heat exchanger, ° a bypass branch of the second expansion device and of the second heat exchanger, • a second loop of coolant in which a coolant circulates, • a two-fluid heat exchanger arranged jointly on the first coolant loop downstream of the compressor, between said compressor and the first expansion device, and on the second fluid loop coolant, so as to allow heat exchanges between the first coolant loop and the second coolant loop, and • an internal heat exchanger, allowing heat exchange between the coolant at the outlet of the heat exchanger bifluid and the refrigerant coming from the bypass branch and / or the second heat exchanger, the first loop of refrigerant fluid also comprising a branch of refrigerant fluid from the second heat exchanger, said branch branch directly connecting the coolant outlet of the second heat exchanger to the coolant inlet of the compressor.

According to one aspect of the invention, the indirect reversible air conditioning circuit comprises a first device for redirecting the refrigerant coming from the first heat exchanger to the second expansion device or to the bypass branch.

According to another aspect of the invention, the indirect reversible air conditioning circuit comprises a second device for redirecting the refrigerant from the second heat exchanger to the branch branch and / or to the internal heat exchanger.

According to another aspect of the invention, the second device for redirection of the coolant comprises:

• a first non-return valve disposed upstream of the internal heat exchanger between said internal heat exchanger and the second heat exchanger, and • a second non-return valve disposed on the branch branch.

According to another aspect of the invention, the first non-return valve and the second non-return valve have pressure drops calibrated so as to define an equal ratio of refrigerant coming from the second heat exchanger passing through said first non-return valve -return and said second non-return valve.

According to another aspect of the invention, the second coolant redirection device comprises a control valve piloted and disposed on the branch branch so as to control the ratio of coolant fluid coming from the second heat exchanger passing through said branch derivation.

According to another aspect of the invention, the second heat transfer fluid loop (B) comprises:

° the two-fluid heat exchanger, ° a first heat transfer fluid circulation pipe comprising a third heat exchanger intended to be traversed by a flow of air inside the motor vehicle, and connecting a first junction point arranged downstream of the 'two-fluid heat exchanger and a second junction point arranged upstream of said two-fluid heat exchanger, ° a second coolant circulation pipe comprising a fourth heat exchanger intended to be traversed by a flow of air outside the motor vehicle, and connecting the first junction point arranged downstream of the two-fluid heat exchanger and the second junction point arranged upstream of said two-fluid heat exchanger, and ° a pump arranged downstream or upstream of the two-fluid heat exchanger, between the first junction point and the second junction point.

According to another aspect of the invention, the second heat transfer fluid loop comprises an electrical element heating the heat transfer fluid disposed, in the direction of circulation of the heat transfer fluid, downstream of the two-fluid heat exchanger, between said two-fluid heat exchanger and the first junction point.

According to another aspect of the invention, the indirect reversible air conditioning circuit comprises a device for redirection of the heat-transfer fluid coming from the dual-fluid heat exchanger towards the first circulation line and / or towards the second circulation line (60) .

According to another aspect of the invention, the indirect reversible air conditioning circuit comprises an accumulator disposed upstream of the internal heat exchanger.

The present invention also relates to a method of operating an indirect reversible air conditioning circuit according to a cooling mode in which:

° the refrigerant circulates successively in the compressor, the two-fluid heat exchanger, the internal heat exchanger and the first expansion device where said refrigerant undergoes a pressure loss, said refrigerant then circulates successively in the first heat exchanger heat, the bypass branch, the refrigerant then passes into the accumulator and then into the internal heat exchanger before returning to the compressor, ° the heat transfer fluid leaving the dual-fluid heat exchanger circulates in the fourth exchanger heat from the second circulation line.

The present invention also relates to a method of operating an indirect reversible air conditioning circuit according to a dehumidification mode in which:

° the refrigerant circulates successively in the compressor, the two-fluid heat exchanger, the internal heat exchanger, the first expansion device where said refrigerant undergoes a pressure loss, said refrigerant then circulates successively in the first heat exchanger heat, the second expansion device that the coolant passes through or bypasses without loss of pressure, the second heat exchanger, a portion of the coolant from the second heat exchanger passing through the internal heat exchanger, another portion of refrigerant from the second heat exchanger passing through the branch branch, the two portions of refrigerant mixing before returning to the compressor, ° a portion of the heat transfer fluid leaving the dual-fluid heat exchanger circulates in the third exchanger of heat from the first circulation line and another portion of the heat transfer fluid ortor at the output of the dual-fluid heat exchanger circulates in the fourth heat exchanger of the second circulation pipe.

The present invention also relates to a method of operating an indirect reversible air conditioning circuit according to a heat pump mode in which:

° the refrigerant circulates successively in the compressor, the two-fluid heat exchanger, the internal heat exchanger, the first expansion device that the refrigerant crosses or bypasses without loss of pressure, said refrigerant then circulates successively in the first heat exchanger, the second expansion device where said refrigerant undergoes a pressure loss, the second heat exchanger, a portion of the refrigerant coming from the second heat exchanger passing through the internal heat exchanger, another portion of coolant coming from the second heat exchanger passing through the branch branch, the two portions of coolant mixing before returning to the compressor, ° the heat transfer fluid leaving the dual-fluid heat exchanger circulates only in the third heat exchanger heat from the first circulation line.

The present invention also relates to a method of operating an indirect reversible air conditioning circuit according to a heat pump mode where the refrigerant captures the heat in the air taken from the passenger compartment and the outside air in which:

° the refrigerant circulates successively in the compressor, the two-fluid heat exchanger, the internal heat exchanger, the first expansion device that the refrigerant passes through and then circulates successively in the first heat exchanger at an evaporation temperature near zero and where the air taken back from the passenger compartment (hot air has a temperature close to 22 ° C) cools and the refrigerant evaporates, the second expansion device where said refrigerant undergoes a pressure loss, the second heat exchanger, a portion of the refrigerant from the second heat exchanger passing through the internal heat exchanger, another portion of the refrigerant from the second heat exchanger passing through the branch branch, the two portions of coolant mixing before returning to the compressor, ° the heat transfer fluid leaving the dual fluid heat exchanger circulates only in the third heat exchanger of the first circulation line.

The present invention also relates to a method of operating an indirect reversible air conditioning circuit according to a defrosting mode in which only the first loop of refrigerant is in operation, the refrigerant circulating successively in the compressor, the two-fluid heat exchanger , the internal heat exchanger and the first expansion device where said refrigerant undergoes a pressure loss, said refrigerant then circulates successively in the first heat exchanger, the bypass branch, the refrigerant then passes through the exchanger internal heat before returning to the compressor.

Other characteristics and advantages of the invention will appear more clearly on reading the following description, given by way of illustrative and nonlimiting example, and the appended drawings among which:

Figure 1 shows a schematic representation of an indirect reversible air conditioning circuit, Figure 2 shows a schematic representation of an expansion device according to an alternative embodiment, Figure 3 shows a schematic representation of the second heat transfer fluid loop of the indirect reversible air conditioning circuit of FIG. 1, according to an alternative embodiment, FIG. 4a shows the indirect reversible air conditioning circuit of FIG. 1 according to a cooling mode, FIG. 4b shows a pressure / enthalpy diagram of the mode of cooling illustrated in FIG. 4a, FIG. 5a shows the indirect reversible air conditioning circuit of FIG. 1 according to a dehumidification mode, FIG. 5b shows a pressure / enthalpy diagram of the dehumidification mode illustrated in FIG. 5a, FIG. 6a shows the indirect reversible air conditioning circuit of figure 1 according to a heat pump mode, figure 6b shows e a pressure / enthalpy diagram of the heat pump mode illustrated in FIG. 6a, FIG. 7 shows the first loop of refrigerant in FIG. 1 according to a first defrosting mode, FIGS. 8 and 9 show the second loops of heat transfer fluid Figures 1 and 3 respectively according to a second defrosting mode, Figure 10 shows a schematic representation of the second heat transfer fluid loop of the indirect reversible air conditioning circuit of Figure 1, according to an electric heating mode.

In the different figures, identical elements have the same reference numbers.

The following embodiments are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the characteristics apply only to a single embodiment. Simple features of different embodiments can also be combined and / or interchanged to provide other embodiments.

In the present description, it is possible to index certain elements or parameters, such as for example first element or second element as well as first parameter and second parameter or even first criterion and second criterion etc. In this case, it is a simple indexing to differentiate and name elements or parameters or criteria that are similar but not identical. This indexing does not imply a priority of an element, parameter or criterion over another and one can easily interchange such names without departing from the scope of this description.

This indexing does not imply an order in time for example to assess this or that criterion.

In the present description, the term "placed upstream" means that one element is placed before another with respect to the direction of circulation of a fluid. Conversely, by "placed downstream" is meant that one element is placed after another with respect to the direction of circulation of the fluid.

Figure 1 shows an indirect air conditioning circuit 1 reversible for a motor vehicle. The term "reversible" is used here rather than the term "reversible" commonly used because in the case of the indirect air conditioning circuit 1 according to the invention, the thermodynamic cycle is not reversible but the system nevertheless makes it possible to produce heat or cold as needed.

This indirect air conditioning circuit 1 includes in particular:

• a first loop of refrigerant A (in solid line) in which a refrigerant circulates, in particular a so-called chemical refrigerant such as R134a or R1234YF, • a second loop of heat transfer fluid B (in dotted line) in which a heat transfer fluid such as glycol water, and • a two-fluid heat exchanger 5 arranged jointly on the first coolant loop A and on the second heat transfer fluid loop B, so as to allow heat exchanges between said first coolant loop A and said second coolant loop B.

The first refrigerant loop A comprises more particularly in the direction of circulation of the refrigerant:

° a compressor 3, ° the two-fluid heat exchanger 5, arranged downstream of said compressor 3, ° a first expansion device 7, ° a first heat exchanger 9, said first heat exchanger 9 being able in particular to be intended to be passed through by an internal air flow 100 to the motor vehicle, ° a second expansion device ff, ° a second heat exchanger 13, said second heat exchanger 13 which can in particular be intended to be traversed by an air flow 200 which can be internal or external to the motor vehicle, said heat exchanger 13 can also be a cooler connected to another thermal management loop of the motor vehicle, and a bypass branch 30 of the second expansion device 11 and of the second heat exchanger 13.

The bypass branch 30 can more specifically connect a first connection point 31 and a second connection point 32.

The first connection point 31 is disposed, in the direction of circulation of the refrigerant, downstream of the first heat exchanger 9, between said first heat exchanger 9 and the second expansion device 11.

The second connection point 32 is itself located downstream of the second heat exchanger 13, between said heat exchanger 13 and the compressor 3.

The first coolant loop A also includes an internal heat exchanger 19 (IHX for “internai heat exchanger”) allowing heat exchange between the coolant at the outlet of the dual fluid heat exchanger 5 and the coolant in outlet of the second heat exchanger 13 or of the first bypass branch 30. This IHX 19 comprises in particular an inlet and an outlet for coolant coming from the second connection point 32, as well as an inlet and an outlet for coolant in from the two-fluid heat exchanger 5.

The first loop of refrigerant A can also include an accumulator 15 disposed upstream of the compressor 3, more precisely upstream of 1ΊΗΧ 19, between said IHX 19 and the second connection point 32. This accumulator 15 allows, upstream of 1ΊΗΧ 19 , to separate the liquid phase and the gas phase from the refrigerant. Only the gaseous phase of the refrigerant passes into 1ΊΗΧ 19 in order to be overheated and then to pass into the compressor 3.

The first refrigerant loop A also comprises a branch 40 for the refrigerant coming from the second heat exchanger 13. This branch 40 directly connects the coolant outlet of the second heat exchanger 13 to the fluid inlet compressor 3 refrigerant. More specifically, the branch branch 40 connects a third connection point 41 and a fourth connection point 42. The first connection point 41 is arranged downstream of the second heat exchanger 13, between said second heat exchanger heat 13 and the second connection point 32. The fourth connection point 42 is when it is arranged downstream of 1ΊΗΧ 19, between said IHX 19 and the compressor 3.

The indirect reversible air conditioning circuit 1 also includes a first device for redirection of the refrigerant which allows the redirection of the refrigerant from the first heat exchanger 9 to the second expansion device 11 or to the first bypass branch 30.

This first device for redirecting the refrigerant fluid may in particular comprise:

• a first stop valve 22 disposed downstream of the first connection point 31, between said first connection point 31 and the second expansion device 11. An alternative to this first stop valve 22 may be that the second expansion valve 11 includes a stop function so as to be able to block the coolant and prevent it from circulating, • a second stop valve 33 disposed on the first bypass branch 30.

Another alternative (not shown) may also be to have a three-way valve at the first connection point 31.

By stop valve, three-way valve or expansion device with stop function is meant here mechanical or electromechanical elements which can be controlled by an electronic control unit on board the motor vehicle.

The indirect reversible air conditioning circuit 1 also includes a second device for redirection of the refrigerant which allows the redirection of the refrigerant from the second heat exchanger 13 to the branch branch 40 and / or to 1ΊΗΧ 19.

According to a first embodiment, the second device for redirection of the refrigerant fluid may in particular comprise:

• a first non-return valve 23a disposed upstream of 1ΊΗΧ 19 between said IHX and the second heat exchanger 13, more precisely between the third connection point 41 and the second connection point 32, and • a second non-return valve 23b disposed on the branch branch 40.

The first non-return valve 23a and the second non-return valve 23b have pressure drops calibrated so as to define the ratio of refrigerant coming from the second heat exchanger 13 passing through them. For example, when the second non-return valve 23b has pressure losses equal to the sum of the pressure losses of the elements present outside the branch branch 40, between the third connection point 41 and the fourth connection point 42, that is to say for example the first non-return valve 23a, the accumulator 15 and 1ΊΗΧ 19, then the proportion of refrigerant passing through 1ΊΗΧ 19 and bypassing it via the branch branch 40 will be equal.

According to a second embodiment, not shown, the second device for redirection of the coolant comprises a control valve controlled and disposed on the branch branch 40. This control valve makes it possible to control the ratio of coolant coming from the second heat exchanger. heat 13 passing through the branch branch 40. This regulation valve can be a mechanical or electromechanical valve which can be controlled by an electronic control unit on board the motor vehicle, for example a linear valve. By linear valve is meant a valve whose opening and closing is done by a linear movement of translation of a valve in the body of the valve.

The first 7 and second 11 expansion devices can be electronic expansion valves, that is to say the pressure of the refrigerant fluid at the outlet is controlled by a solenoid valve whose open position determines the pressure of the fluid at the outlet. Such an electronic expansion valve is in particular capable of allowing the coolant to pass without loss of pressure when said solenoid valve is fully open.

The first 7 and second 11 expansion devices can also be parallel thermostatic expansion valves (that is to say comprising in their bulb the same fluid as in the air conditioning circuit) or crossed (that is to say comprising in their bulb a fluid different from that of the air conditioning system).

Said first 7 and second 11 expansion devices can each be bypassed by a clean bypass line A ', comprising in particular a stop valve 25, as illustrated in FIG. 2. This bypass line A' allows the refrigerant to bypass respectively the first 7 and / or second 11 expansion devices without undergoing a pressure loss. Preferably, at least the second expansion device 11 is a thermostatic expansion valve comprising a bypass line A '.

The second heat transfer fluid loop B can include:

° the two-fluid heat exchanger 5, ° a first circulation pipe 50 of heat transfer fluid comprising a third heat exchanger 54 intended to be traversed by an interior air flow 100 to the motor vehicle, and connecting a first junction point 61 disposed downstream of the dual-fluid heat exchanger 5 and a second junction point 62 disposed upstream of said dual-fluid heat exchanger 5, ° a second circulation pipe 60 of coolant comprising a fourth heat exchanger 64 intended to be traversed by an outside air flow 200 to the motor vehicle, and connecting the first junction point 61 disposed downstream of the dual-fluid heat exchanger 5 and the second junction point 62 disposed upstream of said dual-fluid heat exchanger 5, and ° a pump 17 arranged downstream or upstream of the two-fluid heat exchanger 5, between the first junction point 61 and the second junction point 62.

The indirect reversible air conditioning circuit 1 includes, within the second heat transfer fluid loop B, a device for redirection of the heat transfer fluid from the two-fluid heat exchanger 5 to the first circulation line 50 and / or to the second heat line traffic 60.

As illustrated in FIGS. 1 and 2, said device for redirection of the heat-transfer fluid coming from the dual-fluid heat exchanger 5 can in particular comprise a third stop valve 63 disposed on the second circulation pipe 60 in order to block or not block the heat transfer fluid and prevent it from circulating in said second circulation line 60.

The indirect reversible air conditioning circuit 1 may also include a shutter 310 for blocking the interior air flow 100 passing through the third heat exchanger 54.

This embodiment makes it possible in particular to limit the number of valves on the second loop of heat transfer fluid B and thus makes it possible to limit the production costs.

According to an alternative embodiment illustrated in FIG. 3, the device for redirection of the heat-transfer fluid coming from the dual-fluid heat exchanger 5 can in particular comprise • a third stop valve 63 disposed on the second circulation pipe in order to block or not the heat transfer fluid and prevent it from flowing in said second circulation pipe 60, and • a fourth stop valve 53 disposed on the first circulation pipe in order to block or not the heat transfer fluid and prevent it from circulate in said first circulation pipe 50.

The second heat transfer fluid loop B can also include an electric heating element 55 of the heat transfer fluid. Said electrical heating element 55 is notably arranged, in the direction of circulation of the heat-transfer fluid, downstream of the dual-fluid heat exchanger 5, between said dual-fluid heat exchanger 5 and the first junction point 61.

The present invention also relates to a method of operating the indirect reversible air conditioning circuit 1 according to different operating modes illustrated in FIGS. 4a to 10. In FIGS. 4a, 5a, 6a, 7, 8, 9 and 10 only the elements in which the refrigerant and / or circulating coolant are shown. The direction of circulation of the coolant and / or the coolant is represented by arrows.

FIG. 4a shows a cooling mode in which:

° the refrigerant circulates successively in the compressor 3, the two-fluid heat exchanger 5,1ΊΗΧ 19 and the first expansion device 7 where said refrigerant undergoes a pressure loss, said refrigerant then circulates successively in the first heat exchanger 9, the bypass branch 30, the coolant then passes into 1ΊΗΧ 19 before returning to the compressor 3, ° the heat transfer fluid at the outlet of the dual-fluid heat exchanger 5 circulates in the fourth heat exchanger 64 of the second line of traffic 60.

As illustrated by FIG. 4a, a portion of the heat transfer fluid at the outlet of the dual-fluid heat exchanger 5 circulates in the third heat exchanger 54 of the first circulation pipe 50 and another portion of the heat transfer fluid at the outlet of the exchanger dual-fluid heat 5 circulates in the fourth heat exchanger 64 of the second circulation line 50. The obstruction flap 310 is closed so as to prevent the interior air flow 100 from circulating in the third heat exchanger 54.

The pressure and enthalpy variations undergone by the refrigerant during this cooling mode are illustrated on the pressure / enthalpy diagram in FIG. 4b. Curve X represents the saturation curve of the refrigerant.

The refrigerant at the inlet of compressor 3 is in the gas phase and undergoes compression, illustrated by arrow 300, while passing through compressor 3.

The refrigerant passes through the two-fluid heat exchanger 5 and undergoes a loss of enthalpy, illustrated by arrow 500, due to the passage in the liquid phase of the coolant and the transfer of enthalpy to the heat transfer fluid of the second loop. heat transfer fluid B. The refrigerant then loses enthalpy while remaining at a constant pressure.

The refrigerant then passes into 1ΊΗΧ 19 where it loses enthalpy, as illustrated by the arrow 190a. This enthalpy is transferred to the cooling fluid at the outlet of the bypass branch 30, as illustrated by the arrow 190b.

The refrigerant then passes through the first expansion device 7. The refrigerant undergoes an isenthalpic pressure loss, illustrated by arrow 700 and crosses the saturation curve X, which makes it pass into a state of liquid mixture plus gas.

The refrigerant then passes into the first heat exchanger 9 where it gains enthalpy, as illustrated by the arrow 900, by cooling the interior air flow 100. The refrigerant thus joins the saturation curve X and returns to the gaseous state. At the outlet of the first heat exchanger 9, the refrigerant is redirected to the first bypass branch 30.

The refrigerant then passes into 1ΊΗΧ 19 where it again gains enthalpy, as illustrated by the arrow 190b coming from the refrigerant through 1ΊΗΧ 19 downstream of the two-fluid heat exchanger 5. The refrigerant then returns to the compressor 3.

This cooling mode is useful for cooling the interior air flow 100.

In this cooling mode, the first coolant redirection device is configured so that the coolant does not circulate either in the second expansion device 11 or in the second heat exchanger 13 and passes into the bypass branch 30

This is in particular possible by closing the first stop valve 22 and by opening the second stop valve 33.

The second coolant redirection device is not used because the coolant does not pass through the second heat exchanger

13.

The use of 1ΊΗΧ 19 makes it possible to reduce the enthalpy of the coolant entering the first expansion device 7. The coolant in the liquid state at the outlet of the two-fluid heat exchanger 5 is cooled by the coolant at l gas leaving the first heat exchanger 9. The enthalpy difference across the first heat exchanger 9 increases significantly which allows an increase in the cooling capacity available at said first heat exchanger 9 which cools the flow of air 100 and this therefore leads to an improvement in the coefficient of performance (or COP for “coefficient of performance”).

At the second heat transfer fluid loop B, the heat transfer fluid gains enthalpy from the coolant at the two-fluid heat exchanger 5.

As illustrated in FIG. 4a, a portion of the heat transfer fluid circulates in the first circulation pipe 50 and passes through the third heat exchanger 54. The heat transfer fluid does not, however, lose any enthalpy because the obstruction flap 310 is closed and blocked the interior air flow 100 so that it does not pass through the third heat exchanger 54.

Another portion of the heat transfer fluid circulates in the second circulation line 60 and passes through the fourth heat exchanger 64. The heat transfer fluid loses enthalpy at said heat exchanger 64 by releasing it into the external air flow 200. The third stop valve 63 is open to allow the passage of the heat transfer fluid.

An alternative solution (not shown) so that the heat transfer fluid does not exchange with the interior air flow 100 at the third heat exchanger 54, is to provide, as in FIG. 3, the first circulation pipe 50 with the fourth stop valve 53 and to close it so as to prevent the coolant from flowing in said first circulation pipe 50.

FIG. 5a shows a dehumidification mode in which:

° the refrigerant circulates successively in the compressor 3, the two-fluid heat exchanger 5,1ΊΗΧ 19, the first expansion device 7 where said refrigerant undergoes a pressure loss, said refrigerant then circulates successively in the first heat exchanger 9, the second expansion device 11 that the refrigerant passes through or bypasses without loss of pressure, the second heat exchanger 13, a portion of the refrigerant coming from the second heat exchanger 13 passing through 1ΊΗΧ 19, another portion of fluid refrigerant from the second heat exchanger 13 passing through the branch branch 40, the two portions of refrigerant fluid mixing before returning to the compressor 3, ° a portion of the heat transfer fluid leaving the dual-fluid heat exchanger 5 circulates in the third heat exchanger 54 of the first circulation pipe 50 and another portion of the heat transfer fluid leaves it ie from the two-fluid heat exchanger 5 circulates in the fourth heat exchanger 64 of the second circulation pipe 60.

The pressure and enthalpy variations undergone by the refrigerant during this dehumidification mode are illustrated on the pressure / enthalpy diagram in FIG. 5b. Curve X represents the saturation curve of the refrigerant.

The refrigerant at the inlet of compressor 3 is in the gas phase and undergoes compression, illustrated by arrow 300, while passing through compressor 3.

The refrigerant passes through the two-fluid heat exchanger 5 and undergoes a loss of enthalpy, illustrated by arrow 500, due to the passage in the liquid phase of the coolant and the transfer of enthalpy to the heat transfer fluid of the second loop. heat transfer fluid B. The refrigerant then loses enthalpy while remaining at a constant pressure.

The refrigerant then passes into the first IHX 19 where it loses enthalpy, as illustrated by the arrow 190a. This enthalpy is transferred to the refrigerant downstream of the second heat exchanger 13, as illustrated by the arrow 190b.

The refrigerant then passes through the first expansion device 7. The refrigerant undergoes an isenthalpic pressure loss, illustrated by arrow 700 and crosses the saturation curve X, which makes it pass into a state of liquid mixture plus gas.

The refrigerant then passes into the first heat exchanger 9 where it gains enthalpy as illustrated by the arrow 900 by cooling the interior air flow 100. The refrigerant thus joins the saturation curve X and returns to the gaseous state. At the outlet of the first heat exchanger 9, the refrigerant is redirected to the first bypass branch 30.

At the outlet of the first heat exchanger 9, the refrigerant is redirected to the second expansion device 11 which it passes through or bypasses without loss of pressure.

The refrigerant then passes through the second heat exchanger 13 where it gains enthalpy, as illustrated by arrow 130, by absorbing enthalpy from the flow of outside air 200. The refrigerant thus joins the saturation curve X and returns to the gaseous state.

At the outlet of the second heat exchanger 13, a portion of refrigerant passes through 1ΊΗΧ 19 and gains enthalpy from the coolant at the outlet of the two-fluid heat exchanger 5, this increase in enthalpy is illustrated by the arrow 190b .

At the outlet of the second heat exchanger 13, another portion of refrigerant passes through the branch branch 40 and therefore does not undergo an increase in enthalpy.

The two portions of coolant mix at the fourth connection point 42 and the enthalpy is balanced to reach an intermediate enthalpy illustrated by point 420.

The refrigerant then joins the compressor 3.

In this dehumidification mode, the first coolant redirection device is configured so that the coolant does not circulate in the first bypass branch 30.

This is in particular possible by closing the second shut-off valve 33 so that the refrigerant leaving the first heat exchanger 9 does not circulate in the first bypass branch 30 and passes into the second heat exchanger

13.

The second coolant redirection device is configured so that the coolant circulates both in 1ΊΗΧ 19 and in the branch branch 40.

In this dehumidification mode, the enthalpy supply to the refrigerant at level 1ΊΗΧ 19 is compensated by the refrigerant which passes through the branch branch 40. Thus, arriving at the level of compressor 3, the increase in temperature of the coolant and its drop in density due to the action of 1 l'action 19 will be limited and the coolant will have a temperature low enough not to damage the compressor 3 and a density sufficient for the compressor 3 to be effective.

At the second heat transfer fluid loop B, the heat transfer fluid gains enthalpy from the coolant at the two-fluid heat exchanger 5.

As illustrated in FIG. 5a, a portion of the heat transfer fluid circulates in the first circulation line 50 and passes through the third heat exchanger 54. The heat transfer fluid loses enthalpy by heating the internal air flow 100. For this, the obstruction flap 310 is open or the fourth stop valve 53 is open.

Another portion of the heat transfer fluid circulates in the second circulation line 60 and passes through the fourth heat exchanger 64. The heat transfer fluid loses enthalpy at said heat exchanger 64 by releasing it into the external air flow 200. The third stop valve 63 is open to allow the passage of the heat transfer fluid.

This dehumidification mode is useful for dehumidifying the interior air flow 100 by subjecting it to cooling at the first heat exchanger 9 and by reheating it at the third heat exchanger 54.

FIG. 6a shows a heat pump mode in which:

° the refrigerant circulates successively in the compressor 3, the two-fluid heat exchanger 5,1ΊΗΧ 19, the first expansion device 7 that the refrigerant crosses or bypasses without loss of pressure, said refrigerant then circulates successively in the first exchanger heat 9, the second expansion device 11 where said refrigerant undergoes a pressure loss, the second heat exchanger 13, a portion of the refrigerant from the second heat exchanger 13 passing through 1ΊΗΧ 19, another portion of fluid refrigerant from the second heat exchanger 13 passing through the branch branch 40, the two portions of refrigerant fluid mixing before returning to the compressor 3, ° the heat transfer fluid leaving the dual-fluid heat exchanger 5 circulates only in the third heat exchanger 54 of the first circulation pipe 50.

The pressure and enthalpy variations undergone by the refrigerant during this heat pump mode are illustrated in the pressure / enthalpy diagram in FIG. 6b. Curve X represents the saturation curve of the refrigerant.

The refrigerant at the inlet of compressor 3 is in the gas phase. The refrigerant undergoes compression, illustrated by arrow 300, while passing through the compressor 3.

The refrigerant passes through the two-fluid heat exchanger 5 and undergoes a loss of enthalpy, illustrated by arrow 500, due to the passage in the liquid phase of the coolant and the transfer of enthalpy to the heat transfer fluid of the second loop. heat transfer fluid B. The refrigerant then loses enthalpy while remaining at a constant pressure.

The refrigerant then passes into 1ΊΗΧ 19 where it loses enthalpy, as illustrated by the arrow 190a. This enthalpy is transferred to the refrigerant downstream of the second heat exchanger 13, as illustrated by the arrow 190b.

The refrigerant then passes through the first expansion device 7. The refrigerant passes through the first expansion device 7 without undergoing pressure loss or bypasses it.

The refrigerant then passes through the first heat exchanger 9 where it loses enthalpy, as illustrated by the arrow 900, by heating the interior air flow 100.

At the outlet of the first heat exchanger 9, the refrigerant is redirected to the second expansion device 11 where it undergoes an isenthalpic pressure loss.

The refrigerant then passes through the second heat exchanger 13 where it gains enthalpy, as illustrated by arrow 130, by absorbing enthalpy from the flow of outside air 200. The refrigerant thus joins the saturation curve X and returns to the gaseous state.

At the outlet of the second heat exchanger 13, a portion of refrigerant passes through ΓΙΗΧ 19 and gains enthalpy from the refrigerant at the outlet of the two-fluid heat exchanger 5, this increase in enthalpy is illustrated by arrow 190b .

At the outlet of the second heat exchanger 13, another portion of refrigerant passes through the branch branch 40 and therefore does not undergo an increase in enthalpy.

The two portions of coolant mix at the fourth connection point 42 and the enthalpy is balanced to reach an intermediate enthalpy illustrated by point 420.

The refrigerant then joins the compressor 3.

In this heat pump mode, the first coolant redirection device is configured so that the coolant does not circulate in the first bypass branch 30.

This is in particular possible by closing the second shut-off valve 33 so that the refrigerant leaving the first heat exchanger 9 does not circulate in the first bypass branch 30 and passes into the second heat exchanger

13.

The second coolant redirection device is configured so that the coolant circulates both in 1ΊΗΧ 19 and in the branch branch 40.

In this heat pump mode, the enthalpy contribution to the coolant at 1ΊΗΧ 19 is compensated by the coolant which passes through the branch branch 40. Thus, arriving at the compressor 3, the increase in the temperature of the refrigerant as well as its drop in density due to the action of 1ΊΗΧ 19 will be limited and the refrigerant will have a temperature low enough not to damage the compressor 3 and a density sufficient for the compressor 3 to be effective.

At the second heat transfer fluid loop B, the heat transfer fluid gains enthalpy from the coolant at the two-fluid heat exchanger 5.

As illustrated in FIG. 7a, the heat transfer fluid circulates in the first circulation pipe 50 and passes through the third heat exchanger 54. The heat transfer fluid loses enthalpy by heating the internal air flow 100. For this, the shutter obstruction 310 is open and / or the fourth stop valve 53 is open. The third stop valve 63 is closed in order to prevent the passage of the heat transfer fluid in the second circulation pipe 60.

This heat pump mode is useful for heating the interior air flow 100 both at the level of the first heat exchanger 9 and of the third heat exchanger 54 by absorbing enthalpy of the exterior air flow 200 at the level of the second heat exchanger 13.

In addition, the electric heating element 55 can be in operation in order to provide an additional supply of heat energy to the heat transfer fluid to heat the interior air flow 100.

FIG. 7 shows a first defrosting mode in which only the first loop of refrigerant A is in operation.

In this first defrosting mode, the refrigerant circulates successively in the compressor 3, the two-fluid heat exchanger 5,1ΊΗΧ 19, the first expansion device 7 where said refrigerant undergoes a pressure loss, the first heat exchanger 9 and the second heat exchanger 13. and the second internal heat exchanger 19 'before returning to the compressor 3.

At the outlet of the second heat exchanger 13, a portion of refrigerant passes through 1ΊΗΧ 19. Another portion of refrigerant passes through the branch branch 40.

The two portions of coolant mix at the fourth connection point 42 and the coolant then joins the compressor 3.

This first defrosting mode is useful for supplying hot coolant to the second heat exchanger 13 in order to avoid the formation of frost at its level.

In this first defrosting mode, the first expansion device 7 allows the refrigerant to pass without it undergoing a pressure loss or is bypassed. The refrigerant passes through the first heat exchanger 9 while losing little or no enthalpy, for example due to a stoppage of the interior air flow 100.

The refrigerant then passes through the second expansion device 11 where it does not undergo pressure loss or bypasses it. The refrigerant then passes through the second heat exchanger 13 where it releases its enthalpy in order to avoid the formation of frost.

In this first defrosting mode, the coolant redirection device is configured so that the coolant does not circulate in the bypass line 30.

This is in particular possible by opening the first stop valve 22 and closing the second stop valve 33 so that the coolant leaving the first heat exchanger 9 does not circulate in the bypass line 30 and passes into the second heat exchanger 13.

The second coolant redirection device is configured so that the coolant circulates both in 1ΊΗΧ 19 and in the branch branch 40.

Figures 8 and 9 show a second and a third defrosting mode where only the second heat transfer fluid loop B is in operation.

In the second defrosting mode, illustrated in FIG. 8, the heat transfer fluid propelled by the pump 17 passes through the heat exchanger 5 but does not exchange enthalpy with the coolant of the first coolant loop A of the the latter does not work, for example by stopping compressor 3.

The heat transfer fluid then passes through the electric heating element 55 which is in operation and heats said heat transfer fluid.

A portion of the heat transfer fluid circulates in the first circulation pipe 50 and passes through the third heat exchanger 54. The heat transfer fluid does not, however, lose any enthalpy because the obstruction flap 310 is closed and blocks the internal air flow 100 so that it does not pass through the third heat exchanger 54.

Another portion of the heat transfer fluid circulates in the second circulation line 60 and passes through the fourth heat exchanger 64. The heat transfer fluid loses enthalpy at said heat exchanger 64 by releasing it into the external air flow 200 and allows to heat the second heat exchanger 13 in order to avoid the formation of frost on the latter. The third stop valve 63 is open to allow the passage of the heat transfer fluid.

The third defrosting mode illustrated in FIG. 9 is similar to the second defrosting mode of FIG. 8, with the difference that the heat transfer fluid does not circulate in the first circulation line 50 due to the presence and the closing of the fourth stop valve 53. All the refrigerant therefore passes through the second circulation line 60 and passes through the fourth heat exchanger 64.

Figure 10 shows an electric heating mode where only the second heat transfer fluid loop B is in operation.

In this second mode of electric heating, the heat transfer fluid propelled by the pump 17 passes through the heat exchanger 5 but does not exchange enthalpy with the coolant of the first coolant loop A because the latter does not not working, for example by stopping compressor 3.

The heat transfer fluid then passes through the electric heating element 55 which is in operation and heats said heat transfer fluid.

The heat transfer fluid circulates only in the first circulation line 50 and passes through the third heat exchanger 54. The heat transfer fluid loses heat by transmitting it to the interior air flow 100. In order for the interior air flow 100 to pass through the third heat exchanger 54, the obstruction flap 310 is open and / or the fourth stop valve 53 is open.

The heat transfer fluid does not circulate in the second circulation line 60 because the third stop valve 63 is closed.

Thus, it is clear that due to its architecture, the air conditioning circuit 1 allows operation in a cooling mode having a refrigerating performance and an improved COP thanks to the action of 1ΊΗΧ 19. This IHX 19 having no negative effect on the COP or on the compressor 3 in a heat pump mode or in a dehumidification mode.

Claims (11)

1. Indirect reversible air conditioning circuit (1) for a motor vehicle comprising: A first coolant loop (A) in which a coolant circulates, said first coolant loop (A) comprising in the direction of circulation of the coolant: ° a compressor (3), ° a first expansion device (7), ° a first heat exchanger (9), ° a second expansion device (11), ° a second heat exchanger (13), ° a branch bypass (30) of the second expansion device (11) and of the second heat exchanger (13), • a second loop of heat transfer fluid (B) in which a heat transfer fluid circulates, • a dual-fluid heat exchanger (5) arranged jointly on the first coolant loop (A) downstream of the compressor (3), between said compressor (3) and the first expansion device (7), and on the second coolant loop (B), so that allow heat exchanges between the first coolant loop (A) and the second heat transfer fluid loop (B), and • an internal heat exchanger (19), allowing heat exchange between the coolant leaving the bifluid heat exchanger (5) and the coolant coming from the bran bypass che (30) and / or the second heat exchanger (13), characterized in that the first coolant loop (A) also includes a branch branch (40) of the coolant coming from the second heat exchanger (13), said branch branch (40) directly connecting the coolant outlet of the second heat exchanger (13) to the coolant inlet of the compressor (3). 2. Indirect reversible air conditioning circuit (1) according to the preceding claim, characterized in that it comprises a first device for redirecting the coolant coming from the first heat exchanger (9) to the second expansion device (11) or to the bypass branch (30). 3. Indirect reversible air conditioning circuit (1) according to one of the preceding claims, characterized in that it comprises a second device for redirecting the coolant coming from the second heat exchanger (13) towards the branch branch (40 ) and / or to the internal heat exchanger (19). 4. Indirect reversible air conditioning circuit (1) according to the preceding claim, characterized in that the second device for redirection of the coolant comprises: • a first non-return valve (23a) disposed upstream of the internal heat exchanger (19) between said internal heat exchanger (19) and the second heat exchanger (13), and • a second non-return valve (23b) disposed on the branch branch (40). 5. Indirect reversible air conditioning circuit (1) according to the preceding claim, characterized in that the first non-return valve (23 a) and the second non-return valve (23b) have pressure losses calibrated so as to define a equal ratio of refrigerant coming from the second heat exchanger (13) passing through said first non-return valve (23a) and said second non-return valve (23b). 6. Indirect reversible air conditioning circuit (1) according to the preceding claim, characterized in that the second device for redirection of the coolant comprises a control valve controlled and disposed on the branch branch (40) so as to control the ratio of refrigerant from the second heat exchanger (13) passing through said branch branch. 7. Indirect reversible air conditioning circuit (1) according to one of the preceding claims, characterized in that the second heat transfer fluid loop (B) comprises: ° the two-fluid heat exchanger (5), ° a first circulation pipe (50) of heat transfer fluid comprising a third heat exchanger (54) intended to be traversed by an internal air flow (100) in the motor vehicle, and connecting a first junction point (61) disposed downstream of the dual-fluid heat exchanger (5) and a second junction point (62) disposed upstream of said dual-fluid heat exchanger (5), ° a second circulation pipe (60) of heat transfer fluid comprising a fourth heat exchanger (64) intended to be traversed by an external air flow (200) to the motor vehicle, and connecting the first junction point (61) disposed downstream of the exchanger dual fluid heat (5) and the second junction point (62) disposed upstream of said dual fluid heat exchanger (5), and ° a pump (17) disposed downstream or upstream of the dual fluid heat exchanger (5) , between the first junction point (61) and the second junction point (62). 8. Indirect reversible air conditioning circuit (1) according to the preceding claim characterized in that the second loop of heat transfer fluid (B) comprises an electric heating element (55) of the heat transfer fluid arranged, in the direction of circulation of the heat transfer fluid, downstream of the dual fluid heat exchanger (5), 5 between said two-fluid heat exchanger (5) and the first junction point (61). 9. Indirect reversible air conditioning circuit (1) according to one of claims 7 or 8, characterized in that it comprises a device for redirection of the heat-transfer fluid coming from the two-fluid heat exchanger (5) towards the 10 first circulation line (50) and / or to the second circulation line (60). 10. Indirect reversible air conditioning circuit (1) according to one of the preceding claims, characterized in that it comprises an accumulator (15) arranged in 15 upstream of the internal heat exchanger (19). 1/8