WO2013029747A1

WO2013029747A1 - Refrigerant circuit having two compression stages and an intermediate pressure cylinder

Info

Publication number: WO2013029747A1
Application number: PCT/EP2012/003420
Authority: WO
Inventors: Bertrand Nicolas; Mohamed Yahia; Régine Haller
Original assignee: Valeo Systems Thermiques
Priority date: 2011-08-29
Filing date: 2012-08-09
Publication date: 2013-03-07
Also published as: FR2979287B1; FR2979287A1

Abstract

The invention relates to a circuit (1) for the air-conditioning of a vehicle passenger compartment, including: a first portion (2) of the circuit (1), which extends between an inlet (5) of a first compression means (6) and an outlet (7) of a first expansion member (8), said first portion (2) including at least one outer exchanger (15) dividing said first portion (2) into a first sector (24) located upstream from said outer exchanger (15) and a second sector (24) located downstream from said outer exchanger (15); a third portion (4) of the circuit (1), which extends between an outlet (22) of a second expansion member (25) and an outlet (30) of a second compression means (31), said third portion (4) including an evaporator (32) dividing said third portion (4) between a first area (33) located upstream from the evaporator (32) and a second area (34) located downstream from said evaporator (32), characterized in that the circuit (1) includes a first means (35) which connects the first area (33) to the first sector (23) and a second means (36) which connects the second sector (24) to the second area (34).

Description

REFRIGERANT FLUID CIRCUIT WITH TWO COMPRESSION STAGES AND INTERMEDIATE PRESSURE BOTTLE

The technical sector of the present invention is that of assemblies or systems used to condition a flow of air entering a passenger compartment of a motor vehicle. More particularly, the invention relates to a refrigerant circuit used in heating mode, otherwise called heat pump, cooling mode or dehumidification mode and using three different pressure levels. The invention optimizes the architecture and performance of such a circuit in cooling mode but also in heating mode.

A motor vehicle is conventionally equipped with a loop or air conditioning circuit inside which circulates a refrigerant. This loop conventionally comprises a compressor, a condenser, a pressure reducer and an evaporator traveled in this order by the refrigerant. The evaporator is mounted inside a ventilation, heating and / or air conditioning installation generally placed in the passenger compartment of the vehicle to provide the latter with a flow of hot air or a cold air flow depending on the temperature. a request from the user of the vehicle. The condenser is conventionally installed on the front of the vehicle to be traversed by the flow of air outside the vehicle.

This air conditioning loop can be used in cooling mode or heating mode. In cooling mode, the coolant is sent to the front-end exchanger operating in condenser mode, where the coolant is cooled by the outside air flow. Then, the coolant flows to the pressure reducer where it undergoes a lowering of its pressure before entering the passenger compartment exchanger, the latter operating in evaporator mode. The refrigerant fluid passing through the evaporator is then heated by the flow of air entering the ventilation system, which is correlatively reflected by a cooling of this air flow in order to air condition the passenger compartment of the vehicle. The circuit being a closed loop, the refrigerant then returns to the compressor.

In heating mode, the fluid is circulated by the compressor which sends it to the passenger compartment exchanger, the latter then operating in condenser. The latter then behaves as a condenser, where the coolant is cooled by the air circulating in the ventilation system. This air is heated in contact with the passenger compartment and thus brings calories to the passenger compartment of the vehicle. After passing through the passenger compartment heat exchanger, the refrigerant is expanded by an expansion valve before reaching the front-face exchanger, the latter being used in evaporator mode. The outside air flow then heats the refrigerant. The outside air flow is consequently colder after passing through the front-end heat exchanger compared to its temperature before passing through the passenger compartment heat exchanger. The refrigerant then returns to the compressor.

Such an organization has been improved by completing the air conditioning loop presented above by adding an additional heat exchanger through which the refrigerant fluid and whose function is to heat the air sent into the cabin. Thus, this exchanger called "inside" behaves like a radiator instead of Γ evaporator, in heating mode.

The operation of the loop in the heating mode is limited by the pressure of the refrigerant fluid on the low pressure side. When the outside temperature is low, there is a risk that the pressure of the refrigerant fluid at the low pressure side will fall below atmospheric pressure, which results in a risk of outside air entering the circuit and deformation of the air. pipes. The operation of the loop in the heating mode is also limited by the value of the compression ratio of the compressor. Such difficulties hinder the improvement of a thermodynamic cycle used in the heating mode.

The document US5322424 discloses an air conditioning circuit comprising a compressor equipped with two compression mechanisms. Such a circuit is suitable for operation in cooling mode but it is obviously not suitable for operation in heating mode, that is to say in heat pump. This is a major drawback that the invention also proposes to solve.

The object of the present invention is therefore to solve the defects described above mainly by adapting an air conditioning circuit comprising a double-stage compressor so that it operates effectively in operating mode. cooling, in dehumidification mode and especially in heating mode.

The invention therefore relates to a circuit for thermally conditioning a passenger compartment of a vehicle, comprising:

a first circuit portion which extends between an inlet of a first compression means and an outlet of a first expansion element, said first portion comprising at least one external exchanger sharing said first portion in a first sector situated in upstream of the external exchanger and a second sector located downstream of said external exchanger,

a third portion of the circuit which extends between an outlet of a second expansion member and an outlet of a second compression means, said third portion comprising an evaporator sharing said third portion between a first zone situated upstream of the evaporator and a second zone located downstream of said evaporator, characterized in that the circuit comprises a first means which relates the first zone to the first sector and a second means which relates the second sector to the second zone.

Advantageously, a refrigerant fluid is able to circulate in said circuit to implement at least one heating mode of the passenger compartment and a cooling mode of the passenger compartment.

According to a first characteristic of the invention, the circuit comprises a second circuit portion which extends between the output of the first expansion member and the output of the second expansion member, the output of the second compression means and the input of the second first compression means being in communication with the second portion via a refrigerant phase separation device.

According to a characteristic of the invention, the first means comprises at least one duct extending between the first zone and the first sector and a third branching member which manages a refrigerant circulation in said duct. The third bifurcation member, for example taking the form of a three-way valve with a control member, can then be installed at one or other of the ends of the duct, but it can also be installed in the duct. that is to say between said ends.

According to a second characteristic of the invention, the first means comprises a fourth bifurcation member installed at a confluence of the first sector with said conduit, the third bifurcating member being installed at a confluence of the first zone with said conduit. The confluences are at the ends of said duct, that is to say at the place where the portion and the duct separate or join.

According to another characteristic of the invention, the second means comprises at least one channel which extends between the second sector and the second zone and a fifth bifurcation member which manages a refrigerant circulation in said channel. The fifth bifurcation member, for example taking the form of a three-way valve control member, can then be installed at one or the other end of the channel but it can also be installed in the channel, it that is to say between said ends.

According to another characteristic of the invention, the second means comprises a sixth bifurcation member installed at a confluence of the second zone with said channel, the fifth bifurcation member being installed at a confluence of the second sector with said channel. The confluences in question are at the ends of said channel, that is to say at the place where the portion and the channel separate or join.

According to yet another characteristic of the invention, the refrigerant circulates through the external exchanger in the same direction of circulation when the circuit is operated in the heating mode and cooling mode. In other words, the circuit of the invention is arranged so that the refrigerant does not change direction by switching from one mode to another. This arrangement of the circuit takes in particular the form of the first means and the second means.

Advantageously, the refrigerant circulates through the phase separation device of the refrigerant fluid in the same direction of circulation when the circuit is operated in heating mode, in cooling mode and advantageously in dehumidification mode, the latter corresponding to simultaneous activation of the heating mode and cooling mode. The circuit of the invention is thus arranged so that the refrigerant does not change direction through the phase separation device passing from one mode to another. This arrangement of the circuit takes in particular the form of the first means and the second means.

Advantageously, the refrigerant circulates through the second detent member in the same direction of circulation when the circuit is operated in heating mode, in cooling mode and advantageously in a dehumidification mode. Such a solution optimizes the rate of use of the expansion member, the latter not being used only for the cooling mode. This relaxing organ is thus used for the heating mode and for the dehumidification mode.

Note also that the direction of circulation of the coolant in dehumidification mode in at least one of the three components mentioned above is also identical to the flow direction in heating mode or in cooling mode.

According to a first characteristic of the invention, the first compression means and the second compression means are driven by the same driving element, said element advantageously being an electric motor. In such an embodiment, the two compression means and the electric motor are integrated in the same compressor housing to form a monoblock unit, the electric motor being installed between each compression means.

According to a second characteristic of the invention, the first compression means has a first displacement and the second compression means has a second displacement, the ratio between the second displacement and the first displacement being equal to 1.72 +/- 5% . This ensures that a compression ratio of the first compression means is equal to, or substantially equal to, a compression ratio of the second compression means and this, for a subcritical refrigerant fluid, such as R134a, for example.

According to an example of implementation of this report, the displacement of the second compression means is equal to 19 cm ³ while the displacement of the first compression means is equal to 11 cm ³ .

Note finally that the refrigerant contained in the first portion is at a first pressure, called high pressure because it is the result of a compression action of the first compression means combined with that of the second compression means, while the fluid refrigerant contained in the third portion is at a third pressure, so-called low pressure, after relaxation successively by the expansion members, the refrigerant contained in the second portion being at a second pressure, called intermediate pressure, between the first pressure and the third pressure.

The phase separation device is in turn installed so as to contain the refrigerant fluid subjected to the intermediate pressure.

A first advantage according to the invention lies in the possibility of using a dual-stage compression system both in the cooling mode and also while the circuit is operating in the heating mode. This makes it possible to reach higher levels of high pressure so that the thermodynamic cycle has a higher efficiency, or coefficient of performance, than in the prior art and to limit the discharge temperature of the compression means.

The use of the two compression means in series also increases the enthalpy on the evaporator. Such an increase results in a decrease in the refrigerant flow rate and, consequently, a reduction in the work provided by the compression means. Thus, at iso-performance with the prior art, the invention makes it possible to use a compression means which consumes less energy, or with iso-consumption of energy, the invention provides a greater thermodynamic capacity than that of the prior art.

Another advantage lies in the possibility of increasing the heating power of a circuit according to the invention. Indeed, increasing the enthalpy of the evaporator makes it possible to reduce the refrigerant flow rate in the third portion of the circuit. This has the effect of reducing the pressure losses between the evaporator and the second compression means while ensuring a refrigerant pressure side low pressure, that is to say in the third portion of the circuit, greater than the pressure atmospheric, 1 bar.

Other characteristics, details and advantages of the invention will emerge more clearly on reading the description given below as an indication in relation to drawings in which:

FIG. 1 is a schematic view of the circuit according to the invention, represented in a cooling mode,

FIG. 2 is a schematic view of the circuit of FIG. 1, represented in a use according to a heating mode, - Figure 3 is a schematic view of the circuit of Figure 1, shown in a use in a dehumidification mode.

It should be noted that the figures disclose the invention in detail to implement the invention, said figures can of course be used to better define the invention where appropriate.

FIG. 1 illustrates a circuit 1 according to the invention. The architecture of this circuit will be described in the following, whatever the mode of operation, and then, in a second step, the path taken or borrowed by a refrigerant will be described. circulating in the circuit for each of the modes of operation.

The terms "upstream" and "downstream" used below refer to the direction of movement of the fluid considered in the component or portion considered.

In FIGS. 1 to 3, the circuit 1 comprises portions, sectors or zones in solid lines symbolizing the circulation of the refrigerant during the operating mode under consideration and portions, sectors or dashed zones in which the refrigerant fluid does not circulate. .

The circuit 1, otherwise called air conditioning loop or refrigerant circuit, is a closed loop inside which a refrigerant circulates. The refrigerant fluid is of the type of a subcritical fluid, such as hydrofluorocarbon known by the acronym R134a or a low greenhouse effect refrigerant, that is to say which is able to to offer a sustainable solution for car air conditioners, known as HFO1234yf. It can also be a super-critical fluid, such as carbon dioxide, for example, known as R744. In this case the condenser is replaced by a gas cooler.

Such a circuit serves to condition, that is to say adjust the temperature and humidity, the air present in a passenger compartment of a motor vehicle.

The circuit 1 is divided into several portions in which the pressure of the coolant is different from one portion relative to the other. Circuit 1 therefore comprises a first portion 2, a second portion 3 and a third portion 4.

The first portion 2 extends between an inlet 5 of a first compression means 6 and an outlet 7 of a first expansion member 8. The first compression means 6 is in particular a compressor, for example electric, whose compression mechanism is of the spiral or piston type, driven by an electric motor integrated in a compressor housing. The compression means 6 comprises an outlet 9 connected directly to an internal exchanger 10. According to the invention, the first compression means 6 form a first compression stage by means of which the refrigerant circulates in the circuit 1 and undergoes an elevation of its pressure to go from an intermediate pressure Pi to a high pressure, referenced Hp.

This internal exchanger 10 is arranged to ensure a heat exchange between an interior air flow sent into the passenger compartment and the refrigerant flowing therethrough. This indoor exchanger 10 has the function of heating the indoor air flow when the circuit is used in heating mode or in dehumidification mode. This exchanger is called "interior" in that it is intended to change the temperature of the interior air flow sent into the passenger compartment, that it is directly by exchange with the flow of air passing through this exchanger, or indirectly, especially via a secondary loop (not shown) in which circulates a liquid heat transfer fluid responsible for transporting the heat generated by the inner heat exchanger 10 to a radiator that delivers these calories to the air flow inside.

Immediately downstream of this inner exchanger 10, there is a first bifurcation member 1 1 of the refrigerant. This first bifurcation member 1 1 has the function of diverting the refrigerant from the first portion 2 when the heating mode or the dehumidification mode is activated. This first bifurcation member 11 is for example a three-way valve, comprising for example a movable element capable of controlling the flow from its inlet to one or the other of its outputs.

This first bifurcation device 11 has an inlet 12 through which the refrigerant enters, a first outlet 13 taken by the refrigerant when the cooling mode is active and a second outlet 14 through which the refrigerant flows when the heating mode or the dehumidification mode is active.

The first portion 2 of the circuit 1 further comprises an external exchanger 15 arranged to ensure a heat exchange between the refrigerant and a flow air. The heat exchanger referenced 15 is described as "outside", in that it is arranged to achieve a heat exchange between an air flow outside the passenger compartment of the vehicle and the refrigerant flowing in the circuit 1.

Such an external exchanger 15 can be used as a gas cooler or condenser when the refrigerant circuit is operated in the cooling mode of the air flow sent into the passenger compartment.

This same exchanger can also be used as an evaporator when the refrigerant circuit is operated in heating mode of the air flow sent into the passenger compartment.

The external exchanger 15 shares the first portion 2 of the circuit in two sectors 23 and 24 located on either side of this exchanger. In other words, a first sector 23 is formed by the portion of the first portion 2 located downstream of the external exchanger 15 while the second sector 24 is formed by the portion of the first portion 2 located downstream of the external exchanger 15.

This first portion 2 of circuit 1 continues with a second bifurcation member 16 installed downstream of the external exchanger but directly upstream of the first expansion member 8. This second bifurcation member 16 is in particular a three-way valve comprising, for example a movable element capable of controlling the flow from its input to one or other of its outputs. According to another variant embodiment which simplifies the circuit, this second bifurcation member is a "T" or "Y" connection without any element capable of blocking one or the other of the outlets.

This second bifurcation member has a first inlet 17 through which the refrigerant from the external exchanger 15 enters to be distributed to an outlet 18. The latter is directly connected to an inlet 20 of the first expansion member 8. This second bifurcation member further comprises a second input 19 connected directly to the second output 14 of the first bifurcation member 1 1. A line 21 installed between the second outlet 14 of the first bifurcation member 1 1 and the second inlet 19 of the second member of bifurcation 16 has a function of bypassing the external exchanger 15 by the coolant coming from the first compression means 6, when the circuit is used in the heating mode or in the dehumidification mode. In other words, driving 21 is allows the coolant to flow from the first sector 23 to the second sector 24 without passing through the external exchanger 15.

The first portion 2 of the circuit 1 which, as seen above starts at the inlet 5 of the first compression means 6, ends at the outlet 7 of the first expansion member 8.

Thus, the first portion 2 comprises components installed in series in the circuit 1, these components being at least the first compression means 6, the external exchanger 15 and the first expansion member 8. Advantageously, these components are supplemented by the first bifurcation member 1 1 and the second bifurcation member 16. Advantageously, the inner heat exchanger 10 is part of these components installed in series.

The circuit 1 comprises a second portion 3 which extends between the outlet 7 of the first expansion member 8 and an outlet 22 of a second expansion member 25. The first expansion member 8 is responsible for lowering the pressure of the fluid refrigerant from a high pressure level Hp to a lower level, said intermediate pressure Pi, the latter prevailing in the second portion 3.

A phase separation device 26 of the refrigerant fluid is interposed between the first expansion member 8 and the second expansion member 25. It has a first inlet 27 connected to the outlet 7 of the first expansion element 8 and a first connected outlet 28 at an inlet 29 of the second expansion member 25.

As an exemplary embodiment, the first expansion member 8 and / or the second expansion member 25 may be a thermostatic expansion valve, a calibrated orifice or an electronically controlled expansion valve, or a combination of these embodiments. In the case of a calibrated orifice, that is to say a fixed section, an accumulator will be placed upstream of the compressor to ensure the protection of the compressor against any circulation of coolant in the liquid state.

The circuit 1 comprises a third portion 4 which extends between the second portion 3 and the first portion 2 of the circuit 1.

This third portion 4 starts at the outlet 22 of the second expansion member 25 and ends at an outlet 30 of a second compression means 31. The second compression means 31 is particularly a compressor, for example electric, whose compression mechanism is of the spiral or piston type, driven by an electric motor integrated in a compressor housing.

According to a variant of the invention, such a second compression means 31 is combined with the first compression means 6. In this situation, they are driven by the same drive element and can advantageously be collected in the same compressor housing. In one example, the drive element is an electric motor that simultaneously drives both compression means. Interestingly, the electric motor is disposed between the two compression means, the latter being rotated by a shaft of the electric motor which opens at each end of the electric motor.

According to the invention, the second compression means 31 forms a second compression stage through which the refrigerant circulates in the circuit 1 and undergoes an increase in pressure to go from a low pressure Bp to the intermediate pressure Pi.

The first compression means 6 has a first displacement and the second compression means 31 has a second displacement. According to the invention, a ratio is chosen between the second displacement and the first displacement of 1.72 +/- 5%. According to an exemplary embodiment implementing this ratio, the second displacement is equal to 19 cm ³ while the first displacement is equal to 11 cm ³ .

The third portion 4 further comprises an evaporator 32 arranged to ensure cooling of the internal air flow by heat exchange with the refrigerant. This evaporator 32 is installed in a housing (not shown) so as to be traversed by the interior air flow sent into the cabin of the vehicle. This evaporator 32 is placed upstream of the internal exchanger 10, or the radiator in the case where the circuit comprises a secondary loop, according to the direction of movement of the air flow inside the housing. This component is a heat exchanger intended to cool the interior air flow that passes through when the circuit is in cooling mode or in dehumidification mode. This evaporator 32 correlatively ensures a drying of the interior air flow by condensation on its outer walls, this function being particularly sought when activating the dehumidification mode.

This evaporator 32 is interposed between the second expansion member 25 and the second compression means 31 in order to divide the third portion 4 of the circuit 1 between a first zone 33 situated upstream of the evaporator 32 and a second zone 34 located in downstream of this same evaporator.

The phase separation device 26 of the refrigerant fluid is specifically installed in the circuit 1 between the first compression means 6 and the second compression means 31. In other words, this separation device 26 contains a refrigerant fluid which is subjected to pressure Pi intermediate.

In addition to its first input 27 and its first output 28, the phase separation device 26 comprises a second input 60 and a second output 61. The second input 60 is connected directly to the output 30 of the second compression means 31 and the second output 61 is connected directly to the inlet 5 of the first compression means 6.

The first inlet 27, the second inlet 60 and the second outlet 61 open into an internal volume of the phase separation device 26 where the refrigerant is in the gaseous state. In other words, this first inlet 27, the second inlet 60 and the second outlet 61 pass through an upper wall of the phase separation device 26 and terminate immediately below this upper wall.

The phase separation device 26 is arranged so that the first outlet 28 dips to the bottom of the internal volume of said device in order to capture the cooling fluid in the liquid state. To do this, the phase separation device 26 comprises a tube which has a first end connected to the first outlet 28 and a second end which opens in the immediate vicinity of a bottom which delimits the internal volume of the phase separation device. 26.

The circuit 1 according to the invention has a first means 35 which connects the first zone 33 with the first sector 23 and a second means 36 which connects the second sector 24 with the second zone 34.

The first means 35 comprises at least one duct 37 which extends between the first zone 33 of the third portion 4 and the first sector 23 of the first portion 2 of the circuit 1. This first means 35 also comprises a third bifurcation member 38 installed either at the junction of the first zone 33 with the duct 37 or at the level of the duct 37 and independently of the sector or area concerned, or at the junction of the first sector 23 with the duct 37.

In general, this third bifurcation member 38 manages a circulation of refrigerant fluid in said duct according to the operating mode. This is a three-way valve comprising, for example, a movable element capable of controlling the flow from its inlet to one or other of its outputs.

According to a variant of the invention, the third bifurcation member 38 is installed at a confluence of the first zone 33 with said duct 37, in other words in series with the constituent components of the third portion 4 of the circuit 1. This three-way valve has an inlet 39 directly connected to the outlet 22 of the second expansion element 25, and where a first outlet 40 is directly connected to an inlet 41 of the evaporator 32 while a second outlet 42 is connected to the conduit 37.

According to an exemplary embodiment, the first means 35 comprises a fourth bifurcation member 43 installed at a confluence, that is to say at the junction of the first sector 23 with the duct 37. According to one embodiment, the fourth member bifurcation 43 is a three-way valve interposed between the first outlet 13 of the first bifurcation member 1 1 and an inlet 44 of the outer heat exchanger 15. Alternatively, this fourth bifurcation member is a "T" or "Y" connection devoid of any element likely to block one or the other of the outputs.

This fourth bifurcation member thus comprises an inlet 45 connected directly to the first outlet 13 of the first bifurcation member, a first outlet 46 connected directly to the inlet 44 of the external exchanger 15 and a second outlet 47 connected directly to the duct 37 .

The function of the first means 35 according to the invention is to bypass the second sector 24, including the external exchanger 15, and the second portion 3 while allowing or preventing the circulation of the refrigerant in this first means depending on the mode of operation. circuit operation 1.

The second means 36 according to the invention comprises a channel 48 which extends between the second sector 24 and the second zone 34. This second means 36 also comprises a fifth bifurcation member 49 installed either at the junction of the second sector 24 with the channel 48, or at the channel 48 and independently of the sector or zone concerned, or at the junction of the second zone 34 with the channel 48.

In general, this fifth bifurcation member 49 manages a circulation of refrigerant in the channel depending on the mode of operation.

According to a variant of the invention, the fifth bifurcation member 49 is a three-way valve comprising for example a movable element capable of controlling the flow from its inlet to one or other of its outputs. This fifth bifurcation member is installed at a confluence of the second sector 24 with the channel 48, in other words in series with the constituent components of the first portion 2. This fifth bifurcation member comprises an inlet 50 directly connected to an outlet 51 of

The outer heat exchanger 15, and wherein a first outlet 52 is directly connected to the first inlet 17 of the first expansion member 16 while a second outlet 53 is connected to the channel 48.

According to an exemplary embodiment, the second means 36 comprises a sixth bifurcation member 54 installed at a confluence, that is to say at the

Joining the second zone 34 with the channel 48. This sixth bifurcation member 54 is for example a three-way valve interposed between an outlet 55 of the evaporator 32 and an inlet 56 of the second compression means 31. Alternatively, this sixth bifurcation member 54 is a "T" or "Y" fitting without any element capable of blocking one or the other of the outlets.

This sixth bifurcation member thus comprises a first inlet 57 connected directly to the outlet 55 of the evaporator 32, a second inlet 58 connected directly to the conduit 48 and an outlet 59 connected directly to the inlet 56 of the second compression means.

The function of the second means 36 according to the invention is to circumvent the

Second portion 3 and the first zone, including the evaporator 32, while allowing or preventing the circulation of the refrigerant in this second means depending on the operating mode of the circuit 1.

It will be particularly noted that the first means 35 and the second means 36 are arranged so that the refrigerant circulates through the outer heat exchanger 15 in the same direction of circulation in heating mode, in cooling mode and advantageously in dehumidification mode.

It will also be noted that these means 35 and 36 allow the refrigerant to circulate through the phase separation device 26 of the refrigerant fluid in the same direction of circulation in the heating mode, in the cooling mode and advantageously in the dehumidification mode.

Finally, it should be noted that the first means 35 and the second means 36 provide the possibility for the refrigerant to flow through the second expansion member 25 in the same direction of circulation in the heating mode, in the cooling mode and advantageously in the dehumidification.

After having described in detail the structure of the circuit according to the invention, the circulation of the coolant in this circuit is now explained when it is in operation according to the mode chosen.

Figure 1 illustrates the cooling mode. The arrows symbolize the circulation of the refrigerant in the circuit 1.

The second compression means 31 raises the refrigerant pressure of the so-called low pressure level Bp to the level called the intermediate pressure Pi, the latter being greater than the value of the low pressure.

The refrigerant enters the phase separation device 26 through the second inlet 60 and the liquid phase of the refrigerant accumulates at the bottom of the phase separation device 26, while the gaseous phase remains in the upper part of the internal volume of this device.

This gaseous phase is sucked by the first compression means 6 and is raised to a so-called high pressure level Hp, the value of the latter being greater than the low pressure Bp and the intermediate pressure Pi.

In cooling mode, the refrigerant passes through the inner heat exchanger 10 without undergoing heat exchange with the interior air flow. To do this, a flap (not shown) prevents the flow of air through the inner heat exchanger. Alternatively, the circuit 1 may comprise a bypass line of the inner exchanger 10 which prevents the refrigerant from passing into this exchanger. In any case, the inner heat exchanger 10 is inactive vis- with respect to the interior air flow.

The first bifurcation member 1 1 allows the passage of refrigerant from its inlet 12 to its first outlet 13 and prohibits the circulation of fluid in the pipe 21.

The fourth bifurcation member 43 allows the refrigerant to flow from its first inlet 45 to its outlet 46. In the case of a three-way valve, this prevents any flow from the conduit 37. The refrigerant then passes through the outside exchanger 15 where it is cooled by the outside air flow.

The fifth bifurcation member 49 allows the flow of refrigerant from its inlet 50 to its first outlet 52 and prohibits any circulation of the refrigerant towards the channel 48.

The second bifurcation member 16 lets the refrigerant flow from its first inlet 17 to its outlet 18. In the case of a three-way valve, this prevents any entry of the refrigerant from the pipe 21.

The refrigerant continues its course and passes through the first expansion member 8 where it undergoes a lowering of its pressure to go from the high pressure value Hp to the intermediate pressure value Pi.

The refrigerant then enters the internal volume of the phase separation device 26 through the first inlet 27 and leaves it in the liquid state through the first outlet 28.

By passing through the second expansion member 25, the refrigerant undergoes another lowering of the pressure to go from the value of the intermediate pressure Pi to the value of the low pressure Bp.

The refrigerant continues its course through the third bifurcation member 38 from its inlet 39 to its first outlet 40, the second outlet 42 being closed to prevent any circulation of the refrigerant in the conduit 37.

The refrigerant then passes through the evaporator 32, where it captures the calories present in the interior air flow, thereby conditioning the vehicle interior. The refrigerant fluid thus subjected to low pressure and low temperature then reaches the sixth bifurcation member 54 while flowing from the first inlet 57 to the outlet 59. In the case of a three-way valve, the latter prohibits any circulation from the second entrance 58.

The refrigerant fluid finally returns to the second compression means 31, before performing a new thermodynamic cycle.

It is found that in cooling mode, the pipe 21, the duct 37 and the channel 48 are not traversed by the refrigerant.

Refer to Figure 2 for the description of the heating mode. It will be noted that the refrigerant circulates in the same direction at the heart of the circuit 1 as the direction of circulation for the cooling mode presented above. The following description focuses on the differences and reference is made to the description of Figure 1 for identical elements.

The inner heat exchanger 10 dissipates the calories present in the refrigerant fluid, subjected to high pressure and high temperature, in the interior air flow that passes through it. This ensures the heating of the air sent into the cabin.

The first bifurcation member 11 forces the refrigerant coming from the inlet 12 to circulate towards the second outlet 14, thus preventing any exit of the refrigerant by the first outlet 13.

The high-pressure refrigerant then bypasses the outer heat exchanger 15 passing through the pipe 21 to join the second branching member 16, entering the latter through its second inlet 19 to exit through its outlet 18.

By passing through the second expansion member 25, the coolant undergoes another lowering of the pressure from the value of the intermediate pressure Pi to the value of the low pressure Bp.

The refrigerant continues its course through the third bifurcation member 38 from its inlet 39 to its second outlet 42, the first outlet 40 being closed to prevent any circulation of the refrigerant in direction of the evaporator 32.

The refrigerant then circulates in the first means 35. It thus passes into the duct 37 and joins the fourth bifurcation member 43, for entry into it by its second inlet 47 and exit through its outlet 46.

The refrigerant then reaches the outer heat exchanger 15 and passes through the latter undergoing heating to the benefit of the outside air flow.

The refrigerant then prepares to take the second means 36. It thus enters the fifth bifurcation member 49 through its inlet 50 and out of its second outlet 53 to flow in the channel 48.

The refrigerant then joins the sixth bifurcation member 54 and enters the latter through its second inlet 58 to exit its outlet 59 before returning to the second compression means 31.

Figure 3 illustrates the operation of the circuit in dehumidification mode. This mode of operation is close to that described in Figure 1 and reference is made to the description thereof to know the structure. Note that the refrigerant flows in the same direction at the heart of the circuit 1 as the direction of circulation for the cooling mode shown in Figure 1. The description below focuses on differences compared to the latter.

The dehumidification mode cools and heats successively the flow of indoor air sent into the passenger compartment. While in the cooling mode, the inner heat exchanger 10 was rendered inactive with respect to the interior air flow, it is here crossed by this flow of air in order to dissipate the calories generated by the refrigerant fluid subjected to high pressure Hp and high temperature.

The first bifurcation member 1 1 then receives the refrigerant from the indoor exchanger 10 via its inlet 12. The first outlet 13 is then closed while the second outlet 14 is open, thereby allowing the refrigerant to circulate in the pipe 21.

The second bifurcation member referenced 16 allows an entry of the refrigerant fluid through its second inlet 19 and an outlet thereof through the outlet 18.

In this way, the outer heat exchanger 15 is bypassed since the refrigerant passes through the pipe 21 instead of crossing it. The remainder of the circuit is identical to that detailed with respect to the cooling mode, the evaporator 32 then being active so as to dry out the flow of air sent into the cabin and thus reduce the moisture content present in the cabin of the vehicle.

The above description uses the term "directly" to describe the position of one component over another. This term must be understood in the sense that a first component considered is adjacent to a second component considered, or possibly connected to each other exclusively by a refrigerant transport means which takes, for example, the form of a conduit or tube, especially flexible or rigid. In other words, the first component considered is connected to the second component considered by an inactive means with regard to the thermodynamic cycle that takes place in the circuit.

The description of the modes of operation presented above uses the second and sixth bifurcation members, but the person skilled in the art will be able to adapt the operation in the case where the first means 35 and / or the second means 36 comprise only one valve. three ways.

The above description discloses a bifurcation member that can take the form of three-way valves with control member or "T" connection without a control member.

The invention covers the case where the first means 35, the second means 36 and the duct 21 each comprise at least one three-way valve to allow or interrupt the circulation of fluid in the portion concerned, this valve being able to be placed at one end. or at the other end of the first means 35, the second means 36 or the pipe 21.

In a complementary manner, it is provided by the invention that the first means comprises a three-way valve with a control member at each of its ends.

Alternatively and / or complementary, it is provided by the invention that the second means 36 comprises a three-way valve control member at each of its ends.

Alternatively and / or complementary, it is provided by the invention that the pipe 21 comprises a three-way valve control member at each of its ends. Thus, the invention ultimately covers the case where all the bifurcation members are three-way valves with a control member.

Claims

Circuit (1) for thermally conditioning a passenger compartment of a vehicle, comprising:

a first portion (2) of circuit (1) extending between an inlet (5) of a first compression means (6) and an outlet (7) of a first expansion member (8), said first portion (2) comprising at least one external exchanger (15) sharing said first portion (2) in a first sector (23) located upstream of the external exchanger (15) and a second sector (24) located downstream of said external exchanger (15),

a third portion (4) of the circuit (1) extending between an outlet (22) of a second expansion member (25) and an outlet (30) of a second compression means (31), said third portion (4) comprising an evaporator (32) sharing said third portion (4) between a first zone (33) located upstream of the evaporator (32) and a second zone (34) located downstream of said evaporator (32) characterized in that the circuit (1) comprises a first means (35) which connects the first zone (33) with the first sector (23) and a second means (36) which connects the second sector (24). with the second zone (34).

2. Circuit according to claim 1, comprising a second portion (3) of circuit (1) which extends between the outlet (7) of the first expansion member (8) and the outlet (22) of the second expansion member ( 25), the outlet (30) of the second compression means (31) and the inlet (5) of the first compression means (6) being in communication with the second portion (3) via a device phase separation (26) of the refrigerant.

3. Circuit according to any one of claims 1 or 2, wherein the first means (35) comprises at least one duct (37) extending between the first zone (33) and the first sector (23) and a third bifurcation member (38) which manages a refrigerant circulation in said conduit (37).

4. Circuit according to claim 3, wherein the first means (35) comprises a fourth bifurcation member (43) installed at a confluence of the first sector (23) with said duct (37), the third bifurcation member (38). being installed at a confluence of the first zone (33) with said conduit (37).

The circuit of any one of claims 1 to 4, wherein the second means (36) comprises at least one channel (48) extending between the second sector (24) and the second zone (34) and a fifth bifurcation member (49) which manages a refrigerant circulation in said channel (48).

The circuit of claim 5, wherein the second means (36) comprises a sixth bifurcation member (54) installed at a confluence of the second zone (34) with said channel (48), the fifth bifurcation member (49). ) being installed at a confluence of the second sector (24) with said channel (48).

7. Circuit according to any one of the preceding claims, wherein the refrigerant circulates through the outer heat exchanger (15) in the same direction of circulation when the circuit is operated in a heating mode, in dehumidification mode and in a cooling mode.

8. Circuit according to claim 2, wherein the refrigerant circulates through the phase separation device (26) of the refrigerant in a same direction of circulation when the circuit is operated in a heating mode, dehumidification mode and in a cooling mode.

9. Circuit according to any one of the preceding claims, wherein the coolant flows through the second expansion member (25) in the same direction of circulation when the circuit is operated in a heating mode, in dehumidification mode and in a cooling mode.

10. Circuit according to any one of the preceding claims, wherein the first compression means (6) and the second compression means (31) are driven by a same driving element, said element being advantageously an electric motor.

11. Circuit according to any one of the preceding claims, wherein the first compression means (6) has a first displacement and the second compression means (31) has a second displacement, the ratio between the second displacement and the first displacement. being equal to 1.72 +/- 5%.

12. Circuit according to claim 11, wherein the second displacement is equal to 19 cm ³ while the first displacement is equal to 11 cm ³ .

13. Circuit according to any one of the preceding claims, wherein the refrigerant contained in the first portion (2) is at a first pressure, said high pressure Hp, while the refrigerant contained in the third portion (4) is at a third pressure, said low pressure Bp, the refrigerant contained in a second portion (3) of circuit (1) which extends between the outlet (7) of the first expansion member (8) and the outlet (22) of the second expansion member (25) being at a second pressure, said intermediate pressure Pi, between the first pressure and the third pressure.