Method for controlling a thermal conditioning system

Abstract

The invention relates to a method for controlling a thermal conditioning system (100), comprising: - a refrigerant circuit (10), - a compression device (7) having two inlets (7A, 7B) and one outlet (7C), - a liquid / vapor separator (6), in which the refrigerant circuit (10) comprises: a main loop (A) comprising: - the compression device (7), - a first heat exchanger (1), - a first expansion valve (21), - an inlet (6A) and a first outlet of the liquid / vapor separator (6), - a second expansion valve (22), - a second heat exchanger (2), the refrigerant circuit (10) comprising a bypass branch (B) connecting a second outlet (6C) of the liquid / vapor separator (6) to the second inlet (7B) of the compression device (7), in which the refrigerant exits the first exchanger (1) in a subcooled liquid state,in which the subcooling efficiency (SC) of the refrigerant is controlled at a setpoint value (C_SC). Figure from the abstract: Figure 5,

Description

Title of the invention: Method for controlling a thermal conditioning system. Technical field.

[0001] The present invention relates to the field of thermal conditioning systems. Such systems can, for example, be fitted to motor vehicles. These systems ensure thermal regulation of various vehicle components, such as the passenger compartment or an electrical energy storage battery, when the vehicle is electrically powered. Heat exchange is managed primarily by the compression and expansion of a refrigerant circulating in a circuit containing several heat exchangers. A compressor forces the refrigerant into a high-pressure state, allowing its circulation within the circuit. Previous technique

[0002] The refrigerant can absorb or release heat at various heat exchangers located in the circuit. Typically, a thermal conditioning system can operate in different modes, depending on the sections of the circuit and the heat exchangers through which the refrigerant circulates. Some thermal conditioning systems also use a heat transfer fluid circuit, where the heat transfer fluid can exchange heat both with the refrigerant and with various airflows via heat exchangers located in the fluid circuit. Due to the numerous possibilities for managing the different heat exchanges, optimizing operation can be challenging.

[0003] It is therefore desirable to have methods that allow for optimizing the energy efficiency of thermal conditioning systems, while being simple to implement. Summary

[0004] To this end, a method for controlling a thermal conditioning system is proposed, the thermal conditioning system comprising: - a refrigerant circuit configured to circulate a refrigerant, - a compression device comprising a first inlet, a second inlet and an outlet, - a liquid / vapor separation device comprising an inlet, a first outlet and a second outlet, in which the refrigerant circuit comprises a main refrigerant circulation loop comprising successively, in a direction of refrigerant circulation: - the first input of the compression device, - the output of the compression device, - a first heat exchanger, - a first regulator, - the inlet of the liquid / vapor separation device, - the first output of the liquid / vapor separation device, - a second regulator, - a second heat exchanger, and wherein the refrigerant circuit includes a bypass branch connecting the second outlet of the liquid / vapor separation device to the second inlet of the compression device, The control process includes the following steps: - circulating an initial flow of high-pressure refrigerant through the first heat exchanger where it releases heat, the refrigerant exiting the first heat exchanger in a subcooled liquid state, - to reduce the pressure of the subcooled refrigerant from the first heat exchanger to an intermediate pressure lower than the high pressure, - to circulate the intermediate-pressure refrigerant through the liquid / vapor separation device and divide it into a second flow of gaseous refrigerant circulating in the bypass branch and joining the second inlet of the compression device, and a third flow of liquid refrigerant circulating in the main loop, - reduce the third flow of liquid refrigerant circulating in the main loop to a low pressure below the intermediate pressure, - circulating the refrigerant at low pressure in the second exchanger where it evaporates and joins the first inlet of the compression device, in which a subcooling efficiency of the refrigerant at the outlet of the first exchanger is controlled to a setpoint value.

[0005] By controlling the subcooling efficiency of the high-pressure refrigerant from the first heat exchanger, the coefficient of performance of the thermal conditioning system can be increased. The efficiency of the thermodynamic cycle is improved.

[0006] The features listed in the following paragraphs can be implemented independently of each other or in any technically possible combination:

[0007] The control method is a method for controlling subcooling at the outlet of the first exchanger.

[0008] The thermal conditioning system is, for example, a thermal conditioning system for a motor vehicle.

[0009] The compression device is configured to supply high-pressure refrigerant.

[0010] The first inlet of the compression device is configured to receive low-pressure refrigerant fluid. The second inlet of the compression device is configured to receive intermediate pressure refrigerant.

[0011] The outlet of the compression device is configured to supply high-pressure refrigerant.

[0012] The compression device is configured so that the refrigerant admitted through the first inlet is discharged through the outlet, and the refrigerant admitted through the second inlet is also discharged through the outlet.

[0013] The first exchanger is configured to operate as a refrigerant fluid condenser.

[0014] The first heat exchanger is configured to exchange heat with a first heat transfer fluid.

[0015] The second exchanger is configured to operate as a refrigerant fluid evaporator.

[0016] The second exchanger is configured to exchange heat with a second heat transfer fluid.

[0017] The second flow of gaseous refrigerant circulating in the bypass branch is at intermediate pressure.

[0018] According to one aspect of the proposed control method, in which the first heat exchanger is arranged jointly on the refrigerant circuit and on a heat transfer fluid circuit configured to circulate a heat transfer fluid, so as to allow heat exchange between the refrigerant and the heat transfer fluid, the subcooling efficiency of the refrigerant at the outlet of the first heat exchanger is defined as a ratio between: - the difference between a saturation temperature of the refrigerant in the first exchanger, and a temperature of the refrigerant at the outlet of the first exchanger, and - the difference between the saturation temperature of the refrigerant in the first exchanger, and a temperature of the heat transfer fluid at the inlet of the first exchanger.

[0019] According to an example of implementation of the proposed control process, the setpoint value for the subcooling efficiency of the refrigerant at the outlet of the first exchanger is between 50% and 65%.

[0020] This value range ensures optimized operation of the thermal conditioning system, applicable to all operating conditions of the thermal conditioning system. A simple criterion is thus proposed to ensure rapid development of the thermal conditioning system. Development effort is thereby reduced.

[0021] In other words, the subcooling efficiency of the refrigerant at the outlet of the first exchanger is determined by the equation: (equation 1) [Math. 1] TS_l-TR_laveC: OC - ​​ts_1-TL_1 SC: Determined value of the subcooling efficiency of the refrigerant at the outlet of the first heat exchanger, TS_1: Saturation temperature of the refrigerant in the first exchanger, TR_1: Temperature of the refrigerant at the outlet of the first exchanger, TL_1: Temperature of the heat transfer fluid at the inlet of the first exchanger.

[0022] The saturation temperature of the refrigerant in the first exchanger is the saturation temperature corresponding to a pressure equal to the pressure of the refrigerant in the first exchanger.

[0023] The control process thus comprises a sub-step: - determine a temperature of the refrigerant fluid at the outlet of the first exchanger.

[0024] The control method comprises a substep: - determine a refrigerant fluid pressure in the first exchanger.

[0025] The control process includes a substep: - determine a saturation temperature of the refrigerant in the first exchanger, the saturation temperature corresponding to the determined pressure of the refrigerant in the first exchanger.

[0026] The control process includes a substep: - determine a temperature of the heat transfer fluid at the inlet of the first exchanger.

[0027] The second exchanger is arranged jointly on the refrigerant circuit and on the heat transfer fluid circuit so as to allow heat exchange between the refrigerant and the heat transfer fluid. In other words, the second heat transfer fluid is a heat transfer liquid.

[0028] The first exchanger is configured to be selectively coupled to an airflow inside a passenger compartment of a motor vehicle, or to an airflow outside the passenger compartment of the motor vehicle.

[0029] The second exchanger is configured to be selectively coupled to an outside airflow to the passenger compartment of the motor vehicle, or to an inside airflow to the passenger compartment of the motor vehicle.

[0030] According to an example of implementation of the proposed control method, the thermal conditioning system operates according to a first operating mode called passenger compartment cooling mode, in which: - the first exchanger is thermally coupled with a third heat exchanger configured to exchange heat with an outside airflow to the passenger compartment of a motor vehicle, and - the second exchanger is thermally coupled with a fourth heat exchanger configured to exchange heat with an airflow from inside the passenger compartment of the motor vehicle, and in which the setpoint value for the subcooling efficiency of the refrigerant at the outlet of the first exchanger is between 58% and 62%.

[0031] This reduced range is preferentially applicable to the so-called passenger compartment cooling operating mode.

[0032] The third heat exchanger, called the external radiator, is located on the heat transfer fluid circuit. The third heat exchanger is configured to allow heat exchange between the heat transfer fluid and an outside airflow to the passenger compartment of a motor vehicle.

[0033] The fourth heat exchanger, called the passenger compartment cooling radiator, is also located on the heat transfer fluid circuit. The fourth heat exchanger is configured to allow heat exchange between the heat transfer fluid and an internal airflow to the passenger compartment of the motor vehicle.

[0034] According to an example of an implementation of the proposed control method, the thermal conditioning system operates in a second mode of operation called the passenger compartment heating mode, in which: - the first exchanger is thermally coupled with a fifth heat exchanger configured to exchange heat with an airflow from inside the passenger compartment of the motor vehicle, and - the second exchanger is thermally coupled with the third heat exchanger configured to exchange heat with the outside airflow to the passenger compartment of the motor vehicle, and in which the setpoint value for the subcooling efficiency of the refrigerant at the outlet of the first exchanger is between 53% and 57%.

[0035] This reduced range is preferentially applicable to the so-called passenger compartment heating operating mode.

[0036] The fifth heat exchanger, called the passenger compartment heater core, is also located on the heat transfer fluid circuit. The fifth heat exchanger is configured to allow heat exchange between the heat transfer fluid and an airflow inside the passenger compartment of the motor vehicle.

[0037] The control process comprises the following steps: (i) determine a setpoint for the subcooling efficiency of the refrigerant at the outlet of the first heat exchanger, (ii) determine a value for the subcooling efficiency of the refrigerant at the outlet of the first heat exchanger, (iii) control a refrigerant expansion in the first expansion valve so that the determined value of the refrigerant subcooling efficiency at the outlet of the first exchanger is equal to the subcooling efficiency setpoint.

[0038] The subcooling efficiency setpoint may vary depending on the operating mode of the thermal conditioning system.

[0039] The subcooling efficiency setpoint can be a constant value depending on the operating mode of the thermal conditioning system.

[0040] The subcooling efficiency setpoint can be a tabulated value based on the ambient temperature, the table depending on the operating mode of the thermal conditioning system.

[0041] The control process comprises the following substeps: (iii-1) increase the cross-sectional area of ​​the refrigerant flow through the first expansion valve if the determined subcooling efficiency of the refrigerant at the outlet of the first heat exchanger is greater than the subcooling efficiency setpoint, and (iii-2) decrease a refrigerant passage cross-section through the first expansion valve if the determined subcooling efficiency of the refrigerant at the outlet of the first exchanger is less than the subcooling efficiency setpoint.

[0042] The control process comprises the following steps: (iv) determine an intermediate pressure setpoint, (v) determine a value for the intermediate pressure, (vi) control a refrigerant expansion in the second expansion valve so that the determined value of the intermediate pressure is equal to the intermediate pressure setpoint.

[0043] The control process comprises the following substeps: - increase the cross-sectional area of ​​the refrigerant flowing through the second expansion valve if the determined value of the intermediate pressure is greater than the intermediate pressure setpoint, and - decrease a cross-section of the refrigerant passing through the second expansion valve if the determined value of the intermediate pressure is less than the intermediate pressure setpoint.

[0044] The proposed control method comprises the following steps: - determine a high pressure value, - determine a low pressure value, and the intermediate pressure setpoint can be equal to the square root of the product of the high pressure value and the low pressure value.

[0045] Thus, the two compression stages of the compression device operate with an identical compression ratio. This compression ratio is equal to the square root of the ratio of the high-pressure and low-pressure values. The operation of the compression device is optimized.

[0046] In other words, the intermediate pressure setpoint can be determined by the equation: (equation 2) [Math. 2] C_IP = \lBP*HP âvec ' C_IP: Intermediate pressure setpoint, HP: High pressure value, BP: Low pressure value.

[0047] A thermal conditioning system is also proposed comprising: - a refrigerant circuit configured to circulate a refrigerant, - a compression device comprising a first inlet, a second inlet and an outlet, - a liquid / vapor separation device comprising an inlet, a first outlet and a second outlet, in which the refrigerant circuit comprises a main refrigerant circulation loop comprising successively, in a direction of refrigerant circulation: - the first input of the compression device, - the output of the compression device, - a first heat exchanger, - a first regulator, - the inlet of the liquid / vapor separation device, - the first outlet of the liquid / vapor separation device, - a second pressure regulator, - a second heat exchanger, and wherein the refrigerant circuit includes a bypass branch connecting the second outlet of the liquid / vapor separation device to the second inlet of the compression device, - an electronic control unit configured to implement the process described above.

[0048] According to one embodiment of the thermal conditioning system, the compression device is a two-stage compression compressor, in which: - the first inlet of the compression device is a low-pressure refrigerant inlet, - the second inlet of the compression device is an intermediate-pressure refrigerant inlet, the intermediate pressure being greater than or equal to the low pressure.

[0049] According to another embodiment of the thermal conditioning system, the compression device comprises a first compressor having an inlet and an outlet, and a second compressor having an inlet and an outlet, and: - a first refrigerant circulation channel connecting the outlet of the first compressor to the inlet of the second compressor, and - a second refrigerant circulation channel connects the second inlet of the compression device to the first refrigerant circulation channel.

[0050] According to one embodiment, the main loop of the refrigerant circuit includes a refrigerant accumulation device located downstream of the first exchanger and upstream of the first expansion valve.

[0051] The refrigerant accumulation device can be integrated into the first heat exchanger. The refrigerant accumulation device can be integrated into the first heat exchanger between a first heat exchange section of the first heat exchanger in which the refrigerant is condensed, and a second heat exchange section of the first heat exchanger 1 in which the refrigerant in liquid form is subcooled.

[0052] Alternatively, the main loop of the refrigerant circuit may include a refrigerant accumulation device located downstream of the third heat exchanger and upstream of an inlet of the refrigerant compression device.

[0053] According to one embodiment, the heat transfer fluid circuit comprises a primary heat transfer fluid circulation loop, the primary loop comprising a first circulation pump, the first heat exchanger, the fifth heat exchanger known as the passenger compartment heater radiator.

[0054] The first circulation pump is, for example, a unidirectional pump.

[0055] The heat transfer fluid circuit may include a secondary heat transfer fluid circulation loop, the secondary loop comprising a second circulation pump, the second heat exchanger, the fourth heat exchanger called the passenger compartment cooling radiator.

[0056] The second circulation pump can be a unidirectional pump.

[0057] The heat transfer fluid circuit may include a first branch branch arranged in parallel with the primary loop, the first branch branch including the third heat exchanger called external radiator.

[0058] The third heat exchanger, called the external radiator, is configured to exchange heat with an external airflow to the vehicle's passenger compartment.

[0059] The heat transfer fluid circuit may include a second branch connecting the secondary loop to the first branch.

[0060] The heat transfer fluid circuit may include a third branch connecting the first branch to the secondary loop.

[0061] According to one embodiment of the thermal conditioning system, the heat transfer fluid circuit includes a first three-way valve disposed jointly on the primary loop and on the first branch; the first three-way valve is configured to selectively: - allow the heat transfer fluid from the first exchanger to circulate in the primary loop towards the fifth heat exchanger and prohibit circulation of heat transfer fluid in the first bypass branch, or - allow the heat transfer fluid from the third exchanger to flow in the first branch of the bypass towards the first heat exchanger and prohibit the flow of heat transfer fluid towards the fifth heat exchanger.

[0062] According to one embodiment of the thermal conditioning system, the heat transfer fluid circuit includes a second three-way valve arranged jointly on the secondary loop and on the third bypass branch; the second three-way valve is configured to selectively: - allow the heat transfer fluid from the fourth heat exchanger to flow in the secondary loop to the second heat exchanger and prohibit heat transfer fluid flow in the third bypass branch, or - allow the heat transfer fluid from the third bypass branch to flow to the second heat exchanger and prohibit heat transfer fluid flow to the fourth exchanger.

[0063] The flow rate of heat transfer fluid in the fifth heat exchanger is zero.

[0064] The flow rate of heat transfer fluid in the fourth heat exchanger is zero. Brief description of the drawings

[0065] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analysis of the accompanying drawings, on which:

[0066] [Fig. 1] is a schematic view of a thermal conditioning system that can implement the proposed method,

[0067] [Fig.2] is a block diagram of the proposed process.

[0068] [Fig.3] is a schematic view of a first embodiment of a system of thermal conditioning that can implement the proposed process

[0069] [Fig.4] is a schematic view of a first embodiment of a system of thermal conditioning that can implement the proposed process

[0070] [Fig.5] is a schematic view of the thermal conditioning system of the [Fig. 3], illustrating a first mode of operation,

[0071] [Fig.6] is a schematic view of the thermal conditioning system of the [Fig. 3], illustrating a second mode of operation,

[0072] [Fig.7] represents curves illustrating the operation of the system of thermal conditioning of [Fig.3] according to the first operating mode,

[0073] [Fig.8] represents curves illustrating the operation of the system of thermal conditioning of [Fig.3] according to the second operating mode,

[0074] [Fig.9] represents a partial view of the thermal conditioning system of [Fig. 3], illustrating its operation,

[0075] [Fig. 10] is a diagram illustrating the operation of the system of Thermal conditioning offered. Description of the implementation methods

[0076] To facilitate reading the figures, the various elements are not necessarily drawn to scale. In these figures, identical elements bear the same reference numerals. Certain elements or parameters may be indexed, that is, designated, for example, as first element or second element, or first parameter and second parameter, etc. This indexing aims to differentiate similar, but not identical, elements or parameters. This indexing does not imply a priority of one element or parameter over another, and the designations may be interchanged.

[0077] In the following description, the expression "a first element upstream of a second element" means that the first element is placed before the second element with respect to the direction of flow, or path, of a fluid. Similarly, the term "a first element downstream of a second element" means that the first element is placed after the second element with respect to the direction of flow, or path, of the fluid in question. In the case of the refrigerant circuit, the term "a first element is upstream of a second element" means that the refrigerant flows successively through the first element, then the second element, without passing through the compression device. In other words, The refrigerant fluid exits the compression device, possibly passes through one or more elements, then passes through the first element, then the second element, then returns to the compression device, possibly after passing through other elements.

[0078] The expression "a second element is placed between a first element and a third element" means that the shortest path to go from the first element to the third element passes through the second element.

[0079] When it is specified that a subsystem includes a given element, this does not exclude the presence of other elements in that subsystem.

[0080] The thermal conditioning system 100, which will be described below, comprises an electronic control unit that receives information from various sensors, notably those measuring the characteristics of the refrigerant at various points in the circuit. The electronic control unit also receives commands from the vehicle occupants, such as the desired temperature inside the passenger compartment. The electronic control unit can also receive commands from other electronic subsystems, such as the battery management system for electrical energy storage. The electronic control unit implements control laws to operate the various actuators, thereby ensuring that the thermal conditioning system 100 is controlled in such a way as to maintain the received commands.

[0081] A compression device 7 allows a refrigerant to circulate in a refrigerant circulation circuit 10. The refrigerant circuit 10 forms a closed loop in which the refrigerant can circulate. The refrigerant circuit 10 is leak-proof when it is in its nominal operating condition, that is, without any faults or leaks. Each connection point of the circuit 10 allows the refrigerant to flow into one or the other of the circuit sections that converge at that connection point. The distribution of the refrigerant between the circuit sections that converge at a connection point is achieved by opening or closing the shut-off valves, check valves, or expansion devices included on each of these sections. In other words, each connection point is a means of redirecting the refrigerant arriving at that connection point.Various shut-off valves and check valves thus allow the refrigerant to be selectively directed into the different branches of the refrigerant circuit, in order to ensure different operating modes, as will be described later.

[0082] The refrigerant used by the refrigerant circuit 10 is here a natural fluid, such as R290 or R744. A chemical refrigerant such as R1234yf, or 134a can also be used.

[0083] Each refrigerant expansion device, also called an expansion valve, can be an electronic expansion valve. In an electronic expansion valve, the passage area through which the refrigerant passes can be continuously adjusted between a closed position and a maximum open position. To achieve this, an electronic control module for the expansion valve drives an electric motor that moves a movable shutter, thus controlling the passage area available to the refrigerant.

[0084] The term "interior airflow Fi" refers to an airflow directed towards the passenger compartment of the motor vehicle. This interior airflow Fi may circulate within a heating, ventilation, and / or air conditioning (HVAC) system. This system is not shown in the various figures. A first motor-fan unit, not shown, is located within the HVAC system to increase the flow rate of the interior airflow Fi if necessary.

[0085] The term "external airflow Fe" refers to an airflow that is not directed towards the vehicle's passenger compartment. In other words, this airflow Fe remains outside the vehicle's passenger compartment. A second motor-fan unit, also not shown, can be activated to increase the flow rate of the external airflow Fe if necessary. The airflow provided by both the first and second motor-fan units can be adjusted in real time according to heat exchange requirements, for example, by the electronic control unit of the climate control system 100.

[0086] The term "first exchanger" is equivalent to the term "first heat exchanger". Similarly, the term "internal exchanger" is equivalent to the term "internal heat exchanger". The term "storage device" is equivalent to the term "refrigerant storage device".

[0087] The heat transfer fluid circuit(s) also form one or more closed and sealed circuits in which a heat transfer fluid can circulate.

[0088] A thermal conditioning system 100 is shown in [Fig.1]. The thermal conditioning system 100 is, for example, a thermal conditioning system for a motor vehicle.

[0089] The thermal conditioning system 100 comprises: - a refrigerant circuit 10 configured to circulate a refrigerant, - a compression device 7 comprising a first inlet 7A, a second inlet 7B and an outlet 7C, - a liquid / vapor separation device 6 comprising an inlet 6A, a first output 6B and a second output 6C. The refrigerant circuit 10 comprises a main refrigerant circulation loop A, which includes successively, according to the direction of refrigerant circulation: - the first input 7A of the compression device 7, - the 7C output of the compression device 7, - a first heat exchanger 1, - a first regulator 21, - the 6A input of the liquid / vapor separation device 6, - the first outlet 6B of the liquid / vapor separation device 6, - a second 22 regulator, - a second heat exchanger 2. The refrigerant fluid circuit 10 includes a bypass branch B connecting the second outlet 6C of the liquid / vapor separation device 6 to the second inlet 7B of the compression device 7. The thermal conditioning system 100 includes an electronic control unit 60 configured to implement the process which will be described in detail below.

[0090] The compression device 7 is configured to supply high-pressure refrigerant. The compression device 7 includes a refrigerant outlet 7C and two refrigerant inlets 7A, 7B. The first inlet 7A of the compression device 7 is configured to receive low-pressure refrigerant. The second inlet 7B of the compression device 7 is configured to receive intermediate pressure refrigerant. The 7C outlet of the compression device 7 is configured to supply high-pressure refrigerant.

[0091] The intermediate pressure IP is a pressure greater than or equal to the low pressure BP. High pressure (HP) is a pressure higher than intermediate pressure (IP).

[0092] The compression device 7 is configured so that the refrigerant admitted through the first inlet 7A is discharged through the outlet 7C, and the refrigerant admitted through the second inlet 7B is also discharged through the outlet 7C. The refrigerant discharged from outlet 7C is in a high-pressure gaseous state.

[0093] The compression device 7 can be of different types.

[0094] According to a first embodiment of the thermal conditioning system 100, illustrated in [Fig. 3], the compression device 7 is a two-stage compressor 7, in which: - the first inlet 7A of the compression device 7 is a low-pressure refrigerant inlet, - the second inlet 7B of the compression device 7 is an inlet of intermediate pressure refrigerant fluid, the intermediate pressure being greater than or equal to the low pressure.

[0095] The compressor 7 can draw in refrigerant at low pressure at its first inlet 7A and discharge it at high pressure at its outlet 7C. Similarly, the compressor 7 can draw in refrigerant at intermediate pressure at its second inlet 7B and discharge it at high pressure at its outlet 7C.

[0096] According to a second embodiment of the thermal conditioning system 100, illustrated in [Fig.4], the compression device 7 comprises a first compressor 8 having an inlet 8a and an outlet 8b, and a second compressor 9 having an inlet 9a and an outlet 9b. A first refrigerant circulation channel Cl connects the outlet 8b of the first compressor 8 to the inlet 9a of the second compressor 9, and a second refrigerant circulation channel C2 connects the second inlet 7B of the compression device 7 to the first refrigerant circulation channel Cl.

[0097] In this embodiment, the first compressor 8 can draw in refrigerant at the first inlet 7A at low pressure, and discharge it at an intermediate pressure higher than the low pressure, at its outlet 8c. The second compressor 9 can draw in at its inlet 9a the intermediate pressure refrigerant from the first compressor 7 and the intermediate refrigerant from the bypass branch B.

[0098] According to the embodiments shown, the main loop A of the refrigerant fluid circuit 10 includes a refrigerant fluid accumulation device 19 located downstream of the first heat exchanger 1 and upstream of the first expansion valve 21. Accumulation device 19 is a desiccant bottle. The refrigerant fluid exiting the desiccant bottle is in a liquid state.

[0099] The first exchanger 1 is configured to operate as a refrigerant fluid condenser. The first heat exchanger 1 is configured to exchange heat with a first heat transfer fluid FL

[0100] The second exchanger 2 is configured to operate as a refrigerant fluid evaporator. The second exchanger 2 is configured to exchange heat with a second heat transfer fluid F2.

[0101] According to the example illustrated in Figures 3 and 4, the first heat exchanger 1 is arranged jointly on the refrigerant fluid circuit 10 and on a liquid circuit Heat transfer fluid 20 configured to circulate a heat transfer fluid, so as to allow heat exchange between the refrigerant and the heat transfer fluid.

[0102] The first heat exchanger 1 allows heat exchange between two separate fluids, each circulating in a closed circuit. One of the two fluids is the refrigerant circulating in the refrigerant circuit 10, and the other is the heat transfer fluid circulating in the heat transfer fluid circuit 20. In other words, the first heat transfer fluid Fl is the heat transfer fluid circulating in the heat transfer fluid circuit 20. The heat transfer fluid is, for example, a mixture of water and glycol.

[0103] Similarly, the second heat exchanger 2 is arranged jointly on the refrigerant circuit 10 and on the heat transfer fluid circuit 20 so as to allow heat exchange between the refrigerant and the heat transfer fluid. In other words, the second heat transfer fluid F2 is a heat transfer fluid.

[0104] The first heat exchanger 1 is thermally coupled with a third heat exchanger heat 3 configured to exchange heat with an outside airflow Fe to the passenger compartment of the motor vehicle. The second exchanger 2 is thermally coupled with a fourth heat exchanger 4 configured to exchange heat with an interior airflow Fi to the passenger compartment of the motor vehicle.

[0105] The first exchanger 1 is also thermally coupled with a fifth heat exchanger 5 configured to exchange heat with an interior airflow Fi to the passenger compartment of the motor vehicle. The second exchanger 2 is also thermally coupled with the third heat exchanger 3 configured to exchange heat with the outside airflow Fe to the passenger compartment of the motor vehicle.

[0106] The third heat exchanger 3, called the external radiator, is arranged on the heat transfer fluid circuit 20. The third heat exchanger 3 is configured to allow heat exchange between the heat transfer fluid and an outside airflow Fe to the passenger compartment of the motor vehicle. The third heat exchanger 3 is located, for example, in the front of the vehicle, just behind the grille. The third heat exchanger 3 thus receives the airflow resulting from the vehicle's forward movement. A motor-fan unit, not shown, can be activated to increase the airflow directed at the third heat exchanger 3.

[0107] The fourth heat exchanger 4, called the passenger compartment cooling radiator, is also located on the heat transfer fluid circuit 20. The fourth heat exchanger 4 is configured to allow heat exchange between the heat transfer fluid and an interior airflow Fi to the passenger compartment of the motor vehicle. The fourth heat exchanger 4 helps to cool the passenger compartment.

[0108] The fifth heat exchanger 5, called the passenger compartment heater radiator, is located on the heat transfer fluid circuit 20. The fifth heat exchanger 5 is configured to allow heat exchange between the heat transfer fluid and an interior airflow Fi to the passenger compartment of the motor vehicle. The fifth heat exchanger 5 allows the passenger compartment to be heated. The fourth heat exchanger 4 and the fifth heat exchanger 5 are both located in the heating, ventilation and / or air conditioning system. The fourth heat exchanger 4 is located upstream of the fifth heat exchanger 5 according to the direction of the indoor airflow Fi.

[0109] The heat transfer fluid of circuit 20 ensures thermal coupling between the first exchanger 1 and the third exchanger 3, as well as thermal coupling between the first exchanger 1 and the fifth exchanger 5. Similarly, the heat transfer fluid of circuit 20 ensures thermal coupling between the second exchanger 2 and the fourth exchanger 4, as well as thermal coupling between the second exchanger 2 and the third exchanger 3.

[0110] As schematically illustrated in [Fig.9], the heat transfer fluid circulates in the first exchanger 1 between an inlet ICa and an outlet ICb of heat transfer fluid from the first exchanger 1. The refrigerant fluid circulates in the first exchanger 1 between an inlet IRa and an outlet IRb of the first exchanger 1. Similarly, the heat transfer fluid circulates in the second exchanger 2 between an inlet 2Ca and an outlet 2Cb of heat transfer fluid from the second exchanger 2. The refrigerant fluid circulates in the second exchanger 2 between an inlet 2Ra and an outlet 2Rb. The heat transfer fluid and the refrigerant exchange heat as they circulate in the first exchanger 1. The same is true for the second exchanger 2.

[0111] The architecture of the heat transfer fluid circuit 20 will now be described.

[0112] According to the example illustrated in figures 3 to 6, the heat transfer fluid circuit 20 includes a primary loop 20A for circulating heat transfer fluid.

[0113] The primary loop 20A includes a first circulation pump 31, the first heat exchanger 1, the fifth heat exchanger 5.

[0114] The heat transfer fluid circuit 20 includes a secondary loop 20B for circulating heat transfer fluid.

[0115] The secondary loop 20B includes a second circulation pump 32, the second heat exchanger 2, the fourth heat exchanger 4, called the passenger compartment cooling radiator.

[0116] The first circulation pump 31 is here a unidirectional pump. The second circulation pump 32 is here a unidirectional pump.

[0117] The heat transfer fluid circuit 20 also includes a first branch 20C arranged in parallel with the primary loop 20A. The first branch 20C includes the third heat exchanger 3, called the external radiator.

[0118] The third heat exchanger 3, referred to as the external radiator, is configured to exchange heat with an external airflow Fe to the vehicle's passenger compartment. The third heat exchanger 3 allows heat to dissipate into the external airflow Fe, or to absorb heat from the external airflow Fe.

[0119] The first branch 20C connects a first connection point 51 located on the primary loop 20A between the outlet ICb of the first heat exchanger 1 and a first inlet / outlet of the fifth heat exchanger 5 to a second connection point 52 located on the primary loop 20A between a second inlet / outlet of the fifth heat exchanger 5 and the inlet of the first heat transfer fluid circulation pump 31. The primary loop 20A is formed by the circuit portion 20 comprising, successively according to the direction of flow of the heat transfer fluid: the first pump 31, the inlet ICa of the first heat exchanger 1, the outlet ICb of the first heat exchanger 1, the first connection point 51, the first inlet / outlet of the fifth heat exchanger 5, the second inlet / outlet of the fifth heat exchanger 5, the second connection point 52, and again the first pump 31.

[0120] The heat transfer fluid circuit 20 includes a second branch 20D connecting the secondary loop 20B to the first branch 20C.

[0121] The second branch branch 20D connects a third connection point 53 located on the secondary loop 20B between the outlet of the second exchanger 2 and a first inlet / outlet of the fourth exchanger 4 to a fourth connection point 54 located on the first branch branch 20C between the first connection point 51 and the first inlet / outlet of the third exchanger 3.

[0122] The heat transfer fluid circuit 20 includes a third branch branch 20E connecting the first branch branch 20C to the secondary loop 20B.

[0123] The third branch branch 20E connects a fifth connection point 55 located on the first branch branch 20C between a second inlet / outlet of the third exchanger 3 and the second connection point 52 to a sixth connection point 56 located on the secondary loop 20B between a second inlet / outlet of the fourth exchanger 4 and a second inlet / outlet of the second exchanger 2.

[0124] The heat transfer fluid circuit 20 thus comprises several branches. Valves arranged on the circuit allow different branches or loops of the circuit 20 to be connected or isolated. Different configurations of the heat transfer fluid circuit 20 can therefore be created, depending on the opening of the different valves.

[0125] According to the illustrated example, the heat transfer fluid circuit 20 is equipped with two three-way valves.

[0126] The heat transfer fluid circuit 20 includes a first three-way valve 35 arranged jointly on the primary loop 20A and on the first branch 20C. The first three-way valve 35 is configured to selectively: - allow the heat transfer fluid from the first exchanger 1 to flow in the primary loop 20A towards the fifth heat exchanger 5 and prohibit a flow of heat transfer fluid in the first branch of bypass 20C, or - allow the heat transfer fluid from the third exchanger 3 to flow in the first branch of bypass 20C towards the first heat exchanger 1 and prohibit a flow of heat transfer fluid towards the fifth heat exchanger 5.

[0127] According to the illustrated example, the heat transfer fluid circuit 20 includes a second three-way valve 36 arranged jointly on the secondary loop 20B and on the third branch 20E. The second three-way valve 36 is configured to selectively: - allow the heat transfer fluid from the fourth heat exchanger 4 to circulate in the secondary loop 20B towards the second heat exchanger 2 and prohibit circulation of heat transfer fluid in the third bypass branch 20E, or - allow the heat transfer fluid from the third branch of the 20E branch to flow towards the second heat exchanger 2 and prohibit the flow of heat transfer fluid towards the fourth exchanger 4.

[0128] Each three-way valve includes three inlets / outlets, and allows communication between a first inlet / outlet and either the second inlet / outlet or the third inlet / outlet.

[0129] The first exchanger 1 is configured to be selectively coupled to an interior airflow Fi to a passenger compartment of a motor vehicle, or to an exterior airflow Fe to the passenger compartment of the motor vehicle. This selective coupling is achieved by playing on the position of the three-way valves 35 and 36, which allow the heat transfer fluid from the first exchanger 1 to be directed either to the third exchanger 3, or to the fifth exchanger 5.

[0130] The second exchanger 2 is configured to be selectively coupled to an outside airflow Fe to the passenger compartment of the motor vehicle, or to an inside airflow Fi to the passenger compartment of the motor vehicle. Similar to the first exchanger 1, this selective coupling is achieved by playing on the position of the three-way valves 35 and 36, which allow the heat transfer fluid from the second exchanger 2 to be directed either to the third exchanger 3, or to the fourth exchanger 4.

[0131] Other architectures of the refrigerant circuit 10 are of course possible. In particular, the refrigerant circuit 10 may include one or more additional branches, for example to cool other components such as an electrical energy storage battery.

[0132] Similarly, the heat transfer fluid circuit 20 may include one or more additional branches comprising additional heat exchangers. Other types of valves may also be used. Each three-way valve 35, 36 may, for example, be replaced by two two-way valves.

[0133] We will now describe the proposed control method, aimed at optimizing the operation of the thermal conditioning system 100 previously described.

[0134] A method for controlling a thermal conditioning system 100 is proposed, the thermal conditioning system 100 comprising: - a refrigerant circuit 10 configured to circulate a refrigerant, - a compression device 7 comprising a first inlet 7A, a second inlet 7B and an outlet 7C, - a liquid / vapor separation device 6 comprising an inlet 6A, a first output 6B and a second output 6C, in which the refrigerant circuit 10 comprises a main refrigerant circulation loop A comprising successively, in a direction of refrigerant circulation: - the first input 7A of the compression device 7, - the 7C output of the compression device 7, - a first heat exchanger 1, - a first regulator 21, - the 6A input of the liquid / vapor separation device 6, - the first outlet 6B of the liquid / vapor separation device 6, - a second 22 regulator, - a second heat exchanger 2, in which the refrigerant circuit 10 includes a branch B connecting the second outlet 6C of the liquid / vapor separation device 6 to the second inlet 7B of the compression device 7. The proposed control procedure includes the following steps: - to circulate a first flow Qrl of high-pressure refrigerant (HP) in the first heat exchanger 1 where it releases heat, the refrigerant exiting the first heat exchanger 1 in a subcooled liquid state, - to reduce the subcooled refrigerant from the first heat exchanger 1 to an intermediate pressure IP lower than the high pressure HP, - to circulate the intermediate pressure refrigerant IP in the liquid / vapor separation device 6 and divide it into a second flow Qr2 of gaseous refrigerant circulating in the bypass branch B and joining the second inlet 7B of the compression device 7, and a third flow Qr3 of liquid refrigerant circulating in the main loop A, - to reduce the third flow Qr3 of liquid refrigerant circulating in the main loop A to a low pressure BP lower than the intermediate pressure IP, - to circulate the refrigerant at low pressure BP into the second exchanger 2 where it evaporates and joins the first inlet 7A of the compression device 7, in which a subcooling efficiency SC of the refrigerant at the outlet of the first exchanger 1 is controlled to a setpoint value C_SC.

[0135] The proposed method aims to optimize the operation of the described thermal conditioning system. By controlling the subcooling efficiency of the high-pressure refrigerant from the first heat exchanger 1, the coefficient of performance of the thermal conditioning system 100 can be increased. The efficiency of the thermodynamic cycle is improved.

[0136] The control method is a method for controlling the subcooling at the outlet of the first exchanger 1. More precisely, the control method is a method for controlling the subcooling efficiency at the outlet of the first exchanger 1.

[0137] The refrigerant exits the first heat exchanger 1 in a subcooled liquid state. In other words, the refrigerant exiting the first heat exchanger 1 is in a liquid state, and its temperature is below the saturation temperature of the refrigerant for that pressure.

[0138] Figure 10 schematically describes the operation of the thermal conditioning system when the proposed process is implemented. The diagram in Figure 10 represents the pressure P of the refrigerant as a function of its enthalpy H at various points in the refrigerant circuit 10.

[0139] Curve s represents the saturation curve of the refrigerant used. Point E_7A represents the state of the low pressure refrigerant fluid BP at the inlet of the compression device 7. Point Eil represents the state of the intermediate pressure refrigerant IP after compression by the first compression stage of the compression device 7. Point E_7C represents the state of the high-pressure refrigerant HP at the outlet of the compression device 7. This point also corresponds to the state of the refrigerant at the inlet of the first heat exchanger 1. Point Es corresponds to the saturation point of the high-pressure (HP) refrigerant. Point E_21 corresponds to the state of the refrigerant at the inlet of the first expansion valve 21. Point E_6A corresponds to the state of the intermediate pressure refrigerant IP at the outlet of the first expansion valve 21, and also corresponds to the state at the inlet 6A of the liquid / vapor separation device 6. Point E_6B corresponds to the state of the intermediate pressure refrigerant IP at the first outlet 6B of the liquid / vapor separation device 6. The refrigerant is in a liquid state at this point. Point E_6C corresponds to the state of the intermediate-pressure refrigerant (IP) at the second outlet 6C of the liquid / vapor separation device 6. The refrigerant is in a gaseous state at this point. This point also corresponds to the state of the refrigerant at the second inlet 7C of the compression device 7. Point Ei2 schematically represents the state of the mixture of the intermediate-pressure refrigerant (IP) from the first compression stage of the compression device 7 with the gaseous intermediate-pressure refrigerant (IP) from the liquid / vapor separation device 6. Point E_2a represents the state of the refrigerant fluid at the inlet of the second exchanger 2, i.e. after having been expanded to a low pressure BP by the second expansion valve 22.

[0140] When the compression device 7 comprises two separate compressors 8,9 instead of a two-stage successive compressor, point Eil corresponds to the state at outlet 8b of the first compressor 8. Point Ei2 corresponds to the state at inlet 9a of the second compressor 9, therefore after mixing with the refrigerant fluid from the liquid / vapor separation device 6 and circulating in the bypass branch B.

[0141] On [Fig. 10], the double horizontal arrow SR represents the subcooling of the refrigerant at the outlet of the first exchanger 1, i.e. the difference between the saturation temperature TS_1 of the refrigerant in the first exchanger 1, for the pressure HP, and the temperature TR_1 of the refrigerant at the outlet IRb of the first exchanger 1. The symbol Q1 designates the quantity of heat dissipated at the first exchanger 1. The symbol Q2 designates the quantity of heat absorbed at the second exchanger 2. The second flow rate Qr2 of gaseous refrigerant circulating in the bypass branch B is at intermediate pressure IP. This second flow rate is represented schematically by the line between point E_6A and point E_6C.

[0142] According to one aspect of the proposed control method, in which the first heat exchanger 1 is arranged jointly on the refrigerant circuit 10 and on a heat transfer fluid circuit 20 configured to circulate a heat transfer fluid, so as to allow heat exchange between the refrigerant and the heat transfer fluid, the subcooling efficiency SC of the refrigerant at the outlet of the first heat exchanger 1 is defined as a ratio between: - the difference between a saturation temperature TS_1 of the refrigerant in the first heat exchanger 1, and a temperature TR_1 of the refrigerant at the outlet of the first heat exchanger 1, and - the difference between the saturation temperature TS_1 of the refrigerant in the first exchanger 1, and a temperature TL_1 of the heat transfer fluid at the inlet of the first exchanger 1.

[0143] In other words, the subcooling efficiency SC of the refrigerant at the outlet of the first exchanger 1 is determined by the equation: (equation 1) [Math. 1] TSJh'RJ with ■ TS_1-TL_1 SC: Determined value of the subcooling efficiency SC of the refrigerant at the outlet of the first heat exchanger 1, TS_1: Saturation temperature TS_1 of the refrigerant in the first heat exchanger 1, TR_1: Temperature TR_1 of the refrigerant fluid at the outlet of the first exchanger 1, TL_1: Temperature of the heat transfer fluid at the inlet ICa of the first exchanger 1.

[0144] The subcooling efficiency SC of the refrigerant at the outlet of the first exchanger 1 is called the subcooling percentage, and is a dimensionless parameter. The subcooling efficiency SC is by definition positive, or zero.

[0145] The saturation temperature TS_1 of the refrigerant in the first exchanger 1 is the saturation temperature corresponding to a pressure equal to the pressure P_1 of the refrigerant in the first exchanger 1. On [Fig.9], the dotted arrow TL1 schematically indicates where in the heat transfer fluid circuit 20 the temperature TL_1 refers, and the dotted arrow TRI schematically indicates where in the refrigerant fluid circuit 10 the temperature TR 1 refers.

[0146] The setpoint value C_SC of subcooling efficiency SC of the refrigerant at the outlet of the first exchanger 1 is between 50% and 65%.

[0147] This range of values ​​ensures optimized operation of the thermal conditioning system, applicable to all operating conditions of the thermal conditioning system. A simple criterion is thus proposed to ensure rapid fine-tuning of the thermal conditioning system. The development effort required to optimize the operation of the thermal conditioning system is therefore reduced.

[0148] The control process thus comprises a sub-step: - determine a temperature TR_1 of the refrigerant fluid at the outlet of the first exchanger 1. The control process includes a sub-step: - determine a pressure P_1 of the refrigerant fluid in the first exchanger 1.

[0149] The temperature TR_1 of the refrigerant at the outlet of the first exchanger 1 is for example measured by a measuring sensor placed on the refrigerant circuit near the refrigerant outlet IRb of the first exchanger 1. The pressure P_1 of the refrigerant in the first heat exchanger 1 is for example measured by a measuring sensor placed on the refrigerant circuit near the refrigerant outlet IRb of the first heat exchanger 1. It is also possible to place the measuring sensor near the refrigerant inlet IRa of the first heat exchanger 1, or in the heat exchanger 1 itself. The pressure P_1 of the refrigerant in the first exchanger 1 is considered equal to the high pressure HP of the cycle.

[0150] The control process includes a substep: - determine a saturation temperature TS_1 of the refrigerant in the first exchanger 1, the saturation temperature TS_1 corresponding to the determined pressure P_1 of the refrigerant in the first exchanger 1.

[0151] The saturation temperature is determined for example from a model based on the pressure of the refrigerant fluid, for the refrigerant fluid used.

[0152] The control process includes a substep: - determine a temperature TL1 of the heat transfer fluid at the inlet ICa of the first exchanger 1.

[0153] Figures 5 and 6 illustrate the circulation of the heat transfer fluid and the refrigerant for two distinct operating modes. In these figures, the operating regime is assumed to correspond to a steady state in which operating conditions are stabilized. The flow rate exiting a heat exchanger is therefore equal to the flow rate entering that heat exchanger.

[0154] In [Fig.5], the thermal conditioning system 100 operates according to a first operating mode called passenger compartment cooling mode. In this operating mode: - the first exchanger 1 is thermally coupled with a third heat exchanger 3 configured to exchange heat with an outside airflow Fe to the passenger compartment of a motor vehicle, and - the second exchanger 2 is thermally coupled with a fourth heat exchanger 4 configured to exchange heat with an interior airflow Fi to the passenger compartment of the motor vehicle. In this operating mode, the setpoint value C_SC of subcooling efficiency SC of the refrigerant at the outlet of the first exchanger 1 is between 58% and 62%.

[0155] This reduced range is preferentially applicable to the so-called passenger compartment cooling operating mode.

[0156] Figure 7 illustrates the main operating parameters of the thermal conditioning system in the first operating mode, known as passenger compartment cooling mode. These parameters are expressed as a function of the subcooling efficiency SC. In part A of [Fig.7], the Cl-1 curve corresponds to the coefficient of performance of the thermal conditioning system, In part B of the figure, curve C2-1 corresponds to the high pressure HP of the cycle, curve C3-1 corresponds to the intermediate pressure IP of the cycle, and curve C4-1 corresponds to the low pressure BP of the cycle. In part C of the figure, curve C5-1 corresponds to the power absorbed by the compression device 7, and curve C6-1 corresponds to the total flow rate of refrigerant discharged by the compression device 7.

[0157] As shown by curve C6-1, the flow rate discharged by the compression device 7 decreases as the subcooling efficiency increases. The power consumed by the compression device, curve C5-1, initially decreases as the subcooling efficiency increases, reaches a minimum value, and then increases again for higher values ​​of subcooling efficiency. Curve C1-1 shows a maximum, indicating that the thermodynamic coefficient of performance reaches a maximum value. The C_SC-1 setpoint value range is selected to frame the position of the maximum value, and is indicated by the dotted frame.

[0158] According to this first operating mode, known as passenger compartment cooling: - a first flow Qcl of heat transfer fluid circulates in the primary loop 20A, successively in the first heat exchanger 1 where it receives heat from the fluid refrigerant, in the first branch of bypass 20C, in the third heat exchanger 3 where it releases heat to the outside air flow Fe, in the first branch of bypass 20C, and returns to the first exchanger 1, - a second flow Qc2 of heat transfer fluid circulates in the secondary loop 20B, successively in the second exchanger 2 where it gives up heat to the refrigerant fluid, in the fourth heat exchanger 4 where it receives heat from the indoor air flow Fi, and returns to the second exchanger 2.

[0159] The flow rate of heat transfer fluid in the fifth heat exchanger 5 is zero. The first pump 31 is active. The second pump 32 is active.

[0160] As illustrated in [Fig. 5], the first three-way 51 directs the heat transfer fluid from the first heat exchanger 1 to the third heat exchanger 3. The fifth heat exchanger 5 does not carry a flow of heat transfer fluid. The second three-way 52 directs the heat transfer fluid from the second heat exchanger 2 to the fourth heat exchanger 4. The second branch 20D and the third branch 20E do not carry a flow of heat transfer fluid. The heat transfer fluid circuit 20 is thus, for this first mode of operation, in a configuration in which the heat transfer fluid circulating in the first exchanger 1 also circulates in the third exchanger 3, and does not circulate in any other heat exchanger. Simultaneously, the heat transfer fluid circulating in the second heat exchanger 2 also circulates in the fourth heat exchanger 4 and does not circulate in any other heat exchanger. The heat from the refrigerant, which is absorbed by the heat transfer fluid in the first heat exchanger 1, is thus dissipated into the outside air stream Fe in the third heat exchanger 3. The first heat exchanger 1 is therefore thermally coupled with the third heat exchanger 3. The heat transfer fluid gives up heat to the refrigerant at the second exchanger 2. The cooled heat transfer fluid circulates in the fourth exchanger 4 where it receives heat from the internal airflow Fi. The passenger compartment can thus be cooled.

[0161] In [Fig.6], the thermal conditioning system 100 operates according to a second operating mode called passenger compartment heating mode. In this operating mode: - the first exchanger 1 is thermally coupled with a fifth heat exchanger 5 configured to exchange heat with an interior airflow Fi to the passenger compartment of the motor vehicle, and - the second exchanger 2 is thermally coupled with the third heat exchanger 3 configured to exchange heat with the outside airflow Fe to the passenger compartment of the motor vehicle, and In this operating mode, the setpoint value C_SC of the subcooling efficiency SC of the refrigerant at the outlet of the first exchanger 1 is between 53% and 57%.

[0162] This reduced range is preferentially applicable to the so-called passenger compartment heating operating mode.

[0163] Fig. 8 illustrates the main operating parameters of the thermal conditioning system in the second operating mode, known as passenger compartment heating mode. The parameters shown are the same as in [Fig.7]. The suffix '-1' is replaced by the suffix '-2' for each of the curves, in part A, part B and part C of the figure.

[0164] In this second mode of operation, the general shape of the different curves is the same as for the first mode of operation. The Cl-2 coefficient of performance curve shows a maximum for a subcooling efficiency shifted relative to the first operating mode. The C_SC-2 setpoint value range is selected to frame the position of this maximum value, and is indicated by the dotted frame. The setpoint value C_SC of the subcooling efficiency SC of the refrigerant at the outlet of the first exchanger 1 thus depends on the selected operating mode, in order to optimize the coefficient of performance in each of the operating modes.

[0165] According to the second operating mode, known as passenger compartment heating: - a first flow Qcl of heat transfer fluid circulates in the primary loop 20A, successively in the first exchanger 1 where it receives heat from the refrigerant fluid, in the fifth heat exchanger 5 where it releases heat to the internal air flow Fi, and returns to the first exchanger 1, - a second flow Qc2 of heat transfer fluid circulates in the secondary loop 20B in the second exchanger 2 where it gives up heat to the refrigerant, in the second bypass branch 20D, in the third heat exchanger 3 where it receives heat from the outside air flow Fe, in the third bypass branch 20E, and returns to the second exchanger 2.

[0166] The flow rate of heat transfer fluid in the fourth heat exchanger 4 is zero. The first pump 31 is activated. The second pump 32 is also activated.

[0167] As illustrated in [Fig.6], the first three-way 51 directs the heat transfer fluid from the first exchanger 1 to the fifth exchanger 5. The first branch 20C does not carry a flow of heat transfer fluid. The second three-way 52 directs the heat transfer fluid from the second exchanger 2 to the third exchanger 3. For this, the refrigerant from the second exchanger 2 flows through the second branch of the bypass 20D, passes through the third exchanger 3, then flows through the third branch of the bypass 20E and joins the suction side of the second pump 32. The heat transfer fluid circuit 20 is thus, for this second mode of operation, in a configuration in which the heat transfer fluid circulating in the first exchanger 1 also circulates in the fifth exchanger 5, and does not circulate in any other heat exchanger. Simultaneously, the heat transfer fluid circulating in the second exchanger 2 also circulates in the third exchanger 3 and does not circulate in any other exchanger. The heat supplied by the high-pressure refrigerant, which is received by the heat transfer fluid at the first exchanger 1, is dissipated into the interior airflow Fi at the fifth exchanger 5. The passenger compartment is thus heated. The refrigerant receives heat from the heat transfer fluid at the second exchanger 2. The cooled heat transfer fluid is then heated by the outside air flow Fe at the third exchanger 3. In other words, the heat given to the refrigerant by the heat transfer fluid at the second exchanger 2 is taken from the outside air flow Fe at the third exchanger 3.

[0168] According to the proposed control method: - a first flow Qrl of refrigerant circulates in the compression device 7 where it passes through high pressure, circulates successively in the first heat exchanger 1 where it releases heat, in the first expansion valve 21, and divides into: - a second flow Qr2 of refrigerant circulating in the bypass branch B, and joining the second inlet 7B of the compression device 7, - a third flow Qr3 of refrigerant circulating in the main loop A, successively in the second expansion valve 22 where it undergoes expansion and passes to a low pressure BP lower than the intermediate pressure IP, then in the second exchanger 2 where it evaporates, the low-pressure refrigerant from the second exchanger 2 returning to the first inlet 7A of the compression device 7. The refrigerant travels through the same portions of circuits and the same exchangers in the two modes of operation illustrated.

[0169] A control of the expansion rate carried out by the first expansion valve 21 allows the subcooling efficiency SC to be adjusted to the determined subcooling efficiency setpoint value C_SC.

[0170] The control process comprises the following steps: (i) determine a subcooling efficiency setpoint C_SC of the refrigerant at the outlet of the first heat exchanger 1, (ii) determine a value for the subcooling efficiency SC of the refrigerant at the outlet of the first heat exchanger 1, (iii) control a refrigerant expansion in the first expansion valve 21 so that the determined value of the subcooling efficiency SC of the refrigerant at the outlet of the first exchanger 1 is equal to the subcooling efficiency setpoint C_SC.

[0171] The subcooling efficiency setpoint C_SC may vary depending on the operating mode of the thermal conditioning system. The subcooling efficiency setpoint C_SC is determined in real time

[0172] According to an example of implementation of the process, the subcooling efficiency setpoint C_SC is a constant value dependent on the operating mode of the thermal conditioning system.

[0173] According to another example of implementation of the process, the subcooling efficiency setpoint C_SC is a tabulated value as a function of the ambient temperature, the table depending on the operating mode of the thermal conditioning system. In other words, the setpoint value depends on the selected operating mode, and is adjusted according to the ambient temperature.

[0174] The control process comprises the following substeps: (iii-1) increase the cross-sectional area of ​​the refrigerant flow through the first expansion valve 21 if the determined subcooling efficiency SC of the refrigerant at the outlet of the first heat exchanger 1 is greater than the subcooling efficiency setpoint C_SC, and (iii-2) decrease a refrigerant passage section through the first expansion valve 21 if the determined subcooling efficiency SC of the refrigerant at the outlet of the first exchanger 1 is less than the subcooling efficiency setpoint C_SC.

[0175] In other words, an increase in the degree of opening of the first regulator 21 allows to reduce the subcooling at the outlet of the first exchanger 1. Conversely, a decrease in the degree of opening of the first expansion valve 21 allows to reduce the subcooling at the outlet of the first exchanger 1.

[0176] For a given BP value of the low pressure of the thermodynamic cycle and a given HP value of the high pressure of the cycle, several intermediate pressure values ​​are possible. The proposed process also determines an intermediate pressure setpoint, and adjusts the rate of expansion achieved by the second regulator 22 to reach this intermediate pressure setpoint.

[0177] The control procedure thus comprises the following steps: (iv) determine an intermediate pressure setpoint C_IP, (v) determine an IP value for the intermediate pressure, (vi) control a refrigerant expansion in the second expansion valve 22 so that the determined value IP of the intermediate pressure is equal to the intermediate pressure setpoint C_IP.

[0178] The control process comprises the following substeps: - increase the cross-sectional area of ​​the refrigerant flowing through the second expansion valve 22 if the determined value IP of the intermediate pressure is greater than the intermediate pressure setpoint C_IP, and - decrease a cross-section of the refrigerant fluid passing through the second expansion valve 22 if the determined value IP of the intermediate pressure is less than the intermediate pressure setpoint C_IP.

[0179] In other words, increasing the degree of opening of the second expansion valve 22 reduces the intermediate pressure of the thermodynamic cycle. Conversely, decreasing the degree of opening of the second expansion valve 22 increases the intermediate pressure of the cycle.

[0180] The proposed control method comprises the following steps: - determine a high pressure (HP) value, - determine a BP value of the low pressure, and the C_IP intermediate pressure setpoint can be equal to the square root of the product of the HP value of the high pressure and the BP value of the low pressure.

[0181] Thus, the two compression stages of the compression device 7 operate with an identical compression ratio. This compression ratio is equal to the square root of the ratio of the high pressure (HP) to the low pressure (LP) value. The operation of the compression device 7 is optimized.

[0182] In other words, the intermediate pressure setpoint C_IP can be determined by the equation: (equation 2) [Math. 2] C_IP = \[bp*hp avec : C_IP: Intermediate pressure C_IP setpoint, HP: HP value of the high pressure, BP: BP value of the low pressure.

[0183] The HP value of the high pressure of the cycle is for example between 15 bar and 33 bar. The IP value of the intermediate pressure of the cycle is, for example, between 5 bar and 15 bar. The BP value of the low pressure of the cycle is, for example, between 2 bar and 7 bar.

[0184] The refrigerant storage device 19 can be integrated into the first heat exchanger 1. The refrigerant storage device 19 can be integrated into the first heat exchanger 1 between a first heat exchange section of the first heat exchanger 1 in which the refrigerant is condensed, and a second heat exchange section of the first heat exchanger 1 in which the refrigerant in its liquid state is subcooled. This alternative embodiment has not been shown.

[0185] According to another variant not shown, the main loop A of the refrigerant circuit 10 may include a refrigerant accumulation device disposed downstream of the second exchanger 2 and upstream of an inlet 7A of the refrigerant compression device 7. In this case, the refrigerant accumulation device is an accumulator.

Claims

Demands

1. A method for controlling a thermal conditioning system (100), the thermal conditioning system (100) comprising: - a refrigerant circuit (10) configured to circulate a refrigerant, - a compression device (7) having a first inlet (7A), a second inlet (7B) and an outlet (7C), - a liquid / vapor separation device (6) having an inlet (6A), a first outlet (6B) and a second outlet (6C), in which the refrigerant circuit (10) has a main refrigerant circulation loop (A) comprising successively, in a direction of refrigerant circulation: - the first inlet (7A) of the compression device (7), - the outlet (7C) of the compression device (7), - a first heat exchanger (1), - a first expansion valve (21), - the inlet (6A) of the liquid / vapor separation device (6),- the first outlet (6B) of the liquid / vapor separation device (6), - a second expansion valve (22), - a second heat exchanger (2), and wherein the refrigerant circuit (10) includes a bypass branch (B) connecting the second outlet (6C) of the liquid / vapor separation device (6) to the second inlet (7B) of the compression device (7), the control method comprising the steps: - circulating a first flow (Qrl) of refrigerant at high pressure (HP) in the first heat exchanger (1) where it releases heat, the refrigerant exiting the first heat exchanger (1) in a subcooled liquid state, - expanding the subcooled refrigerant from the first heat exchanger (1) to an intermediate pressure (IP) lower than the high pressure (HP),- to circulate the intermediate pressure (IP) refrigerant through the liquid / vapor separation device (6) and divide it into a second flow (Qr2) of gaseous refrigerant circulating in the bypass branch (B) and joining the second inlet (7B) of the, compression device (7), and a third flow (Qr3) of liquid refrigerant circulating in the main loop (A), - expand the third flow (Qr3) of liquid refrigerant circulating in the main loop (A) to a low pressure (BP) lower than the intermediate pressure (IP), - circulate the refrigerant at low pressure (BP) into the second exchanger (2) where it evaporates and joins the first inlet (7A) of the compression device (7), in which a subcooling efficiency (SC) of the refrigerant at the outlet of the first exchanger (1) is controlled to a setpoint value (C_SC).

2. A control method according to claim 1, wherein the first heat exchanger (1) is arranged jointly on the refrigerant circuit (10) and on a heat transfer fluid circuit (20) configured to circulate a heat transfer fluid, so as to permit heat exchange between the refrigerant and the heat transfer fluid, wherein the subcooling efficiency (SC) of the refrigerant at the outlet of the first heat exchanger (1) is defined as a ratio between: - the difference between a saturation temperature (TS_1) of the refrigerant in the first heat exchanger (1), and a temperature (TR_1) of the refrigerant at the outlet of the first heat exchanger (1), and - the difference between the saturation temperature (TS_1) of the refrigerant in the first heat exchanger (1), and a temperature (TL_1) of the heat transfer fluid at the inlet of the first heat exchanger (1),and in which the setpoint value (C_SC) of the subcooling efficiency (SC) of the refrigerant at the outlet of the first heat exchanger (1) is between 50% and 65%.

3. A control method according to claim 1 or 2, wherein the thermal conditioning system (100) operates according to a first operating mode called the passenger compartment cooling mode, in which: - the first heat exchanger (1) is thermally coupled with a third heat exchanger (3) configured to exchange heat with an outside airflow (Fe) to a passenger compartment of a motor vehicle, and - the second exchanger (2) is thermally coupled with a fourth heat exchanger (4) configured to exchange heat with an interior airflow (Fi) to the passenger compartment of the motor vehicle, and in which the setpoint value (C_SC) of subcooling efficiency (SC) of the refrigerant at the outlet of the first exchanger (1) is between 58% and 62%.

4. A control method according to claim 1 or 2, wherein the thermal conditioning system (100) operates according to a second operating mode called passenger compartment heating mode, wherein: - the first heat exchanger (1) is thermally coupled with a fifth heat exchanger (5) configured to exchange heat with an interior airflow (Fi) to the passenger compartment of the motor vehicle, and - the second heat exchanger (2) is thermally coupled with the third heat exchanger (3) configured to exchange heat with the exterior airflow (Fe) to the passenger compartment of the motor vehicle, and wherein the setpoint value (C_SC) of subcooling efficiency (SC) of the refrigerant at the outlet of the first heat exchanger (1) is between 53% and 57%.

5. A control method according to any one of the preceding claims, comprising the steps: (i) determining a subcooling efficiency setpoint (C_SC) of the refrigerant at the outlet of the first heat exchanger (1), (ii) determining a value of the subcooling efficiency (SC) of the refrigerant at the outlet of the first heat exchanger (1), (iii) controlling an expansion of the refrigerant in the first expansion valve (21) so that the determined value of the subcooling efficiency (SC) of the refrigerant at the outlet of the first heat exchanger (1) is equal to the subcooling efficiency setpoint (C_SC).

6. A control method according to the preceding claim, comprising the substeps: (iii-1) increasing the cross-sectional area of ​​the refrigerant through the first expansion valve (21) if the subcooling efficiency (SC) of the refrigerant at the outlet of the first exchanger (1) is greater than the subcooling efficiency setpoint (C_SC), and (iii-2) decrease a refrigerant passage cross-section through the first expansion valve (21) if the determined subcooling efficiency (SC) of the refrigerant at the outlet of the first exchanger (1) is less than the subcooling setpoint (C_SC).

7. A control method according to any one of the preceding claims, comprising the steps: (iv) determining an intermediate pressure setpoint (C_IP), (v) determining an intermediate pressure value (IP), (vi) controlling a refrigerant expansion in the second expansion valve (22) so that the determined intermediate pressure value (IP) is equal to the intermediate pressure setpoint (C_IP).

8. A control method according to the preceding claim, comprising the substeps: - increasing a cross-section of the refrigerant through the second expansion valve (22) if the determined value (IP) of the intermediate pressure is greater than the intermediate pressure setpoint (C_IP), and - decreasing a cross-section of the refrigerant through the second expansion valve (22) if the determined value (IP) of the intermediate pressure is less than the intermediate pressure setpoint (C_IP).

9. A control method according to claim 7 or 8, comprising the steps: - determining a value (HP) of the high pressure, - determining a value (BP) of the low pressure, in which the intermediate pressure setpoint (C_IP) is equal to the square root of the product of the value (HP) of the high pressure and the value (BP) of the low pressure.

10. Thermal conditioning system (100) comprising: - a refrigerant circuit (10) configured to circulate a refrigerant, - a compression device (7) comprising a first inlet (7A), a second inlet (7B) and an outlet (7C), - a liquid / vapor separation device (6) comprising an inlet (6A), a first outlet (6B) and a second outlet (6C), in which the refrigerant circuit (10) comprises a main refrigerant circulation loop (A) comprising successively, in a direction of refrigerant circulation: - the first inlet (7A) of the compression device (7), - the outlet (7C) of the compression device (7), - a first heat exchanger (1), - a first expansion valve (21), - the inlet (6A) of the liquid / vapor separation device (6), - the first outlet (6B) of the liquid / vapor separation device (6), - a second expansion valve (22), - a second heat exchanger (2), and in which the refrigerant circuit (10) comprises a bypass branch (B) connecting the second outlet (6C) of the liquid / vapor separation device (6) to the second inlet (7B) of the compression device (7), - an electronic control unit (60) configured to implement the method according to one of the preceding claims.

11. Thermal conditioning system (100) according to the preceding claim, wherein the compression device (7) is a two-stage compression compressor (7), wherein: - the first inlet (7A) of the compression device (7) is a low-pressure refrigerant inlet, - the second inlet (7B) of the compression device (7) is an intermediate-pressure refrigerant inlet, the intermediate pressure being greater than or equal to the low pressure.

12. Thermal conditioning system (100) according to claim 10 or 11, wherein the compression device (7) comprises a first compressor (8) having an inlet (8a) and an outlet (8b), and a second compressor (9) having an inlet (9a) and an outlet (9b), in which: - a first refrigerant (Cl) circulation channel (Cl) connects the outlet (8b) of the first compressor (8) to the inlet (9a) of the second compressor (9), and - a second refrigerant circulation channel (C2) connects the second inlet (7B) of the compression device (7) to the first refrigerant circulation channel (Cl).

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