FR3079669A1 - THERMAL MANAGEMENT CIRCUIT OF AN ELECTRICAL STORAGE DEVICE OF A MOTOR VEHICLE AND ASSOCIATED STEERING METHOD - Google Patents

Abstract

The present invention relates to a thermal management circuit (1) of an electrical storage device (D) of a motor vehicle inside which a refrigerant circulates, and comprising at least one battery module (M), the thermal management circuit (1) comprising at least one compressor (3), a first heat exchanger (5), a first expansion device (7) and at least one heat exchange device (9) disposed at the each battery module (M), the heat exchange device (9) comprising a distribution switch (11) and at least a first heat exchange zone (9a) and a second heat exchange zone (9b) connected in series, said distribution switch (11) being configured to redirect the coolant first to the first heat exchange zone (9a) and recover the refrigerant at the outlet of the second zone exchange (9b) in a first sense of circu or to redirect the coolant first to the second heat exchange zone (9b) and recover the refrigerant at the outlet of the first exchange zone (9a) in a second direction of circulation.

Description

The present invention relates to the field of thermal management circuits for vehicles, in particular for motor vehicles, and more particularly, the present invention relates to thermal management circuits allowing thermal regulation of an electrical storage device intended for electric motor vehicles or hybrids.

These vehicles, whether fully electric or hybrid, that is to say combining the use of a heat engine and an electric motor, therefore require a substantial supply of electrical energy and are equipped with electrical storage devices. , usually comprising several battery modules. Battery modules, that is to say a plurality of electric cells connected to each other, are thus arranged in the chassis of these vehicles. These battery modules do not support functioning well outside of a determined temperature range, generally around 45 ° C. Outside this temperature range, the operation of the battery modules and its service life may be reduced. In addition, above this temperature range, the battery modules can reach high temperatures at which it can deteriorate. This is particularly the case when charging the battery modules.

It is known to use a refrigerant circuit, also used to heat or cool different areas or different components of the vehicle, to cool or heat the electrical storage device as needed.

For example, the refrigerant circuit may be sufficient to cool the battery modules during a conventional charging phase of the vehicle's electrical storage device, namely a charging phase carried out by connecting the vehicle for several hours. to the domestic electrical network. This charging technique keeps the temperature of the electrical storage device below a certain threshold, which makes it possible to reduce the dimensions of the thermal management circuit of the electrical storage device, in particular for its cooling.

However, a new rapid charging technique has appeared recently. It consists in charging the electrical storage device under a high voltage and amperage, so as to charge the electrical storage device in a time reduced by a few tens of minutes. However, this rapid charge implies a significant heating of the electrical storage device due to a Joule effect as well as exothermic chemical reactions which imposes a larger dimensioning of the heat exchanger (s) intended for thermal regulation of the device. electrical storage. However, if the need for cooling of the electrical storage device is very high during rapid charging phases, this need decreases during driving or so-called “conventional” charging phases. The use of an oversized heat exchanger then unnecessarily consumes energy or generates weight and / or size. Another important point during this rapid charge is to have homogeneous cooling of the batteries and battery modules in particular in order to allow the shortest possible rapid charge.

The present invention proposes to at least partially resolve the drawbacks of the prior art and proposes a thermal management circuit as well as its control method allowing homogeneous thermal management of the battery modules.

The present invention therefore relates to a thermal management circuit of an electrical storage device of a motor vehicle inside which circulates a cooling fluid, the electrical storage device comprising at least one battery module, the thermal management circuit comprising at least, in the direction of circulation of the coolant, a compressor, a first heat exchanger intended to be traversed by an external air flow, a first expansion device and at least one heat exchange device disposed at the level of each battery module, the heat exchange device comprising a switch for distributing the coolant coming from the first expansion device and at least a first heat exchange zone and a second heat exchange zone connected in series, said distribution switch being configured so as to redirect the coolant e n first to the first heat exchange zone and recover the refrigerant leaving the second exchange zone in a first direction of circulation, or redirect the refrigerant first to the second heat exchange zone and recover the refrigerant at the outlet of the first exchange zone in a second direction of circulation.

The fact that the exchange device allows circulation in a first and a second direction makes it possible, by alternating these directions of circulation, to have a more uniform thermal management at the level of the battery module.

According to one aspect of the invention, the heat exchange device is a heat exchanger comprising a refrigerant circulation channel comprising countercurrent circulation branches arranged in series, the first corresponding heat exchange zone to a first circulation branch and the second heat exchange zone corresponding to a second circulation branch.

According to another aspect of the invention, the heat exchange device comprises, a plurality of heat exchangers, the first heat exchange zone corresponding to a first heat exchanger and the second heat exchange zone corresponding to a second heat exchanger.

According to another aspect of the invention, the distribution switch comprises:

° a coolant inlet connected to the first expansion device, ° at least a first controllable coolant inlet-outlet and connected to the first heat exchange zone, ° a second controllable coolant inlet-outlet and connected to the second heat exchange zone, and ° a coolant outlet through which the coolant having passed through the heat exchange device is discharged.

According to another aspect of the invention, the distribution switch is a four-way valve connected to the inlet, to the outlet as well as to the various inlets of coolant.

According to another aspect of the invention, the distribution switch comprises a plurality of connections connecting the inlet as well as the outlet with each of the coolant input-outputs, each of the connections comprising a controllable blocking means of the coolant in order to define its destination.

According to another aspect of the invention, the thermal management circuit comprises at least two battery modules and at least two associated heat exchange devices, said heat exchange devices being connected in parallel with each other, the first expansion device being common for said heat exchange devices.

According to another aspect of the invention, the thermal management circuit comprises at least one primary branch comprising the first expansion device and the at least one heat exchange device and at least one secondary branch arranged in parallel with the at least one primary branch and comprising, in the direction of circulation of the refrigerant, a second expansion device and a second heat exchanger.

According to another aspect of the invention, the thermal management circuit comprises on its primary branch, a third expansion device disposed downstream of the heat exchange device (s).

The present invention also relates to a method for controlling a thermal management circuit, said thermal management circuit comprising at least, in the direction of circulation of the coolant, a compressor, a first heat exchanger intended to be traversed by a flow. of external air, a first expansion device and at least one heat exchange device disposed at each battery module, according to any one of the preceding claims, said heat exchange device comprising a distribution switch refrigerant from the first expansion device and at least a first heat exchange zone and a second heat exchange zone connected in series, said distribution switch being configured so as to redirect the refrigerant first to the first heat exchange zone and recover the refrigerant leaving the the second exchange zone in a first direction of circulation, or to redirect the refrigerant first to the second heat exchange zone and recover the refrigerant leaving the first exchange zone in a second direction of circulation , said method comprising a cooling cycle of a battery module, said cooling cycle comprising a first cooling step during which the refrigerant circulates in the first direction of circulation and a second cooling step during which the refrigerant circulates in the second direction of traffic.

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

Figure 1 shows a schematic representation of an electrical storage device, Figures 2 and 3 show a schematic representation of the thermal management circuit according to a first embodiment, Figures 4 and 5 show a schematic representation of the thermal management circuit according to a second embodiment, Figures 6 and 7 show a schematic representation of the coolant distribution switch according to two embodiments, Figure 8 shows a schematic representation of the thermal management circuit according to a third embodiment, Figure 9 shows a schematic representation of the thermal management circuit according to a fourth embodiment.

Identical elements in the different figures have the same references.

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

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

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

Figure 1 shows a schematic representation of an electrical storage device D of a motor vehicle. This electrical storage device D comprises at least one battery module M. By battery modules M is meant more particularly a plurality of electrical cells connected to each other. These battery modules M are arranged in the electric or hybrid motor vehicle, for example in the chassis or in the trunk. Each battery module M is individually cooled by at least one dedicated heat exchange device 9.

In the example presented in FIG. 1, the electrical storage device D comprises three battery modules M placed side by side, however it is quite possible to imagine an electrical storage device D comprising battery modules M placed in different places of the motor vehicle.

In FIGS. 2 to 5 and 7, the direction of circulation of the coolant is represented by arrows.

Figures 2 and 3 show schematic representations of a thermal management circuit 1 inside which circulates a refrigerant for an electrical storage device D.

The thermal management circuit 1 comprises at least, in the direction of circulation of the coolant, a compressor 3 and a first heat heat exchanger 5 intended to be traversed by an external air flow 100. This first heat exchanger 5 more particularly corresponding to a condenser for example disposed at the front face of the motor vehicle.

Downstream of the first heat exchanger 5, the thermal management circuit 1 is divided into a primary branch A and a secondary branch B. The primary A and secondary B branches are arranged in parallel with one another and are connected to the level of a first connection point 19a disposed downstream of the first heat exchanger 5 and of a second connection point 19b disposed upstream of the compressor 3.

The primary branch A comprises, in the direction of circulation of the refrigerant, a first expansion device 7 and at least one heat exchange device 9 disposed at each battery module M.

More particularly, the heat exchange device 9 comprises:

• a distribution switch 11 for the refrigerant coming from the first expansion device 7, • at least a first heat exchange zone 9a and a second heat exchange zone 9b connected in series.

This distribution switch 11 is configured so as to:

• redirect the coolant first to the first heat exchange zone 9a and recover the coolant at the outlet of the second heat exchange zone 9b in a first direction of flow, as illustrated in Figure 2, or • redirect the refrigerant first to the second heat exchange zone 9b and recover the refrigerant leaving the first heat exchange zone 9a in a second direction of flow, as illustrated in FIG. 3. The heat exchange zones 9a, 9b play the role of an evaporator and in particular allow the cooling of the battery modules M.

The fact that the exchange device 9 allows circulation in a first and a second direction makes it possible, by alternating these directions of circulation, to have a more uniform thermal management at the level of the battery module M. This is particularly the case during fast charging where the cooling requirements are high and where good homogeneity of this cooling over the entire surface of the battery modules M is important.

In fact, in the first direction of circulation, the first exchange zone 9a is reached first and therefore the temperature difference between the refrigerant and the first exchange zone 9a is maximum. When the coolant arrives at the second exchange zone 9b, the temperature difference between the coolant and the second exchange zone 9b is less and therefore the heat exchanges are also less. Conversely, in the second direction of traffic, it is the second exchange zone 9b is reached first and the first exchange zone 9a then. By alternating the directions of circulation it is therefore possible to homogenize the temperature at the level of the battery module and thus to cool it more efficiently.

The secondary branch B may, for its part, in the direction of circulation of the refrigerant, a second expansion device 13 and a second heat exchanger 15. This second heat exchanger 15 may in particular be intended to allow exchanges directly or indirectly with an internal air flow 200 intended to supply the passenger compartment of the motor vehicle.

The second heat exchanger 15 can be directly traversed by the internal air flow 200 as illustrated in FIG. 2. In this case, this second heat exchanger 15 can be an evaporator and be placed in a heating, ventilation and air conditioning (HVAC in English for Heating, Ventilation ans AirConditioning).

The second heat exchanger 15 can also be connected to a second thermal management circuit, for example a heat transfer fluid circuit which will itself be in contact with the internal air flow 200 in the heating, ventilation and air conditioning device.

Other types of secondary branch B may nevertheless be possible, for example a secondary branch B allowing operation in a heat pump mode making it possible to heat the internal air flow 200.

The first and second expansion devices 7, 13, can in particular include a stop function in order to block or not the circulation of the refrigerant and to control in which branch the refrigerant circulates. An alternative solution is to provide the primary branch A and / or the secondary branch B with a shut-off valve.

The thermal management circuit 1 may also include an internal heat exchanger 17 so as to allow heat exchanges between the refrigerant fluid at the outlet of the first heat exchanger 5 and the refrigerant fluid upstream from the inlet of the compressor 3. This internal heat exchanger 17 makes it possible in particular to improve the performance coefficient of the thermal management circuit 1.

According to a first embodiment illustrated in FIGS. 2 and 3, the heat exchange device 9 can be a heat exchanger comprising a channel for the circulation of the refrigerant fluid comprising counter-current circulation branches and arranged in series. The first heat exchange zone 9a then corresponds to a first circulation branch and the second heat exchange zone 9b corresponds to a second circulation branch. Such a heat exchanger is for example a cold plate intended to be placed under a battery module or else in between two battery modules M. This cold plate in particular comprises a channel in circulation in "U" of the refrigerant formed by two branches of series circulations.

According to a second embodiment illustrated in Figures 4 and 5, the heat exchange device 9 may include a plurality of heat exchangers. The first heat exchange zone 9a then corresponds to a first heat exchanger and the second heat exchange zone 9b corresponds to a second heat exchanger. In the example presented in FIGS. 4 and 5, the heat exchange device 9 comprises two heat exchangers connected in series.

The present invention is not limited to two heat exchange zones 9a, 9b. Indeed it is entirely possible to imagine alternative embodiments in which the heat exchange device 9 comprises more than two heat exchange zones 9a, 9b connected in series. In particular in the context of the first embodiment, the heat exchanger may include more than two channels. In the second embodiment, the heat exchange device may include more than two heat exchangers connected in series.

In order to be able to implement the two directions of circulation of the coolant, as illustrated in FIGS. 6 and 7, the distribution switch 11 comprises in particular:

• an inlet 1 la of coolant connected to the first expansion device 7, • at least a first inlet-outlet 11c of controllable coolant and connected to the first heat exchange zone 9a, • a second inlet-outlet lld of controllable coolant connected to the second heat exchange zone 9b, and • an outlet 11b of coolant through which the coolant having passed through the heat exchange device 9 is discharged.

The distribution switch 11 is notably configured so that in the first direction of circulation (illustrated in FIGS. 2 and 4) the inlet 11a is connected to the first inlet-outlet 11c so that the refrigerant fluid coming from the first expansion device 7 circulates first in the first exchange zone 9a. The refrigerant then circulates in the second exchange zone 9b, passes through the second inlet-outlet 1 Id which is itself connected to the outlet 11b in order to evacuate the refrigerant to the compressor 3.

The distribution switch 11 is also configured so that in the second direction of circulation (illustrated in FIGS. 3 and 5) the inlet 11a is connected to the second inlet-outlet 11d so that the refrigerant fluid coming from the first expansion device 7 circulates first in the second exchange zone 9b. The refrigerant then circulates in the first exchange zone 9c, passes through the first inlet-outlet 11c which is in turn connected to the outlet 11b in order to evacuate the refrigerant to the compressor 3.

According to a first embodiment illustrated in FIG. 6, the distribution switch 11 can be a four-way valve. This four-way valve is arranged so as to be connected to the inlet 11a, to the outlet 11b as well as to the various outlets lld, 1 lc of refrigerant.

According to a second embodiment illustrated in Figure 7, the distribution switch 11 may include a plurality of connections connecting the inlet 11a as well as the outlet 11b with each of the input-outputs 11b, 11c of refrigerant. The distribution switch 11 comprises at each of its connections a controllable blocking means 110 of the refrigerant in order to define its destination. In the example illustrated in FIG. 7, these controllable blocking means 110 are shut-off valves placed on each connection.

FIG. 8 shows an alternative embodiment in which the thermal management circuit 1 comprises at least two battery modules M and at least two associated heat exchange devices 9, 9 ’. These heat exchange devices 9, 9 'are connected in parallel to each other in the primary branch A. The first expansion device 7 is common for said heat exchange devices 9, 9', that is that is to say that the various heat exchange devices 9, 9 ′ are all supplied with the refrigerant coming from the first expansion device 7.

The fact of connecting the different heat exchange devices 9, 9 'in parallel and that the first expansion device 7 is common to said heat exchange devices 9, 9', in particular allows the temperature difference between the fluid refrigerant and the battery modules M are the same at each heat exchange device 9, 9 '.

In addition, it is also thus possible to control to which heat exchange device 9, 9 ′ the refrigerant can go, for example by completely closing the distribution switches 11 or by means of dedicated shut-off valves (not shown) .

According to a last embodiment illustrated in FIG. 9, the thermal management circuit 1 can comprise on its primary branch A, downstream of the heat exchange device (s) 9, a third expansion device 21. This third device detent 21 can in particular be able to be crossed without loss of pressure or else bypassed by a bypass branch C comprising a stop valve 23.

This third expansion device 21 allows in particular that the refrigerant leaving the first expansion device 7 can have a pressure different from that of the refrigerant leaving the second expansion device 13. This thus makes it possible to control the level of heat exchange at the heat exchange device 9 and the second heat exchanger 15 independently of one another. The third expansion device 21 then allows the refrigerant leaving the primary branch A to be at the same pressure as the refrigerant leaving the secondary branch B before entering the compressor 3.

The present invention also relates to a method for controlling a thermal management circuit 1. This method notably includes a cooling cycle of a repeated battery module. A cooling cycle comprises a first cooling step during which the refrigerant circulates in the first direction of circulation and a second cooling stage during which the refrigerant circulates in the second direction of circulation.

During the transition from one direction of circulation to another, the circulation of the refrigerant in the heat exchange device 9 is stopped. This stopping of the circulation of the refrigerant fluid can be achieved in particular by closing the distribution switch 11 of said heat exchange device 9 in order to have individual control of each heat exchange device 9. Another solution can also be a closure of the first expansion device 7 which allows a general shutdown of the refrigerant throughout the primary branch A.

This cooling cycle by alternating the directions of circulation makes it possible to have a more uniform thermal management at the level of the battery module. This is particularly the case during rapid charging of the batteries where the cooling requirements are high and where good homogeneity of this cooling over the entire surface of the battery modules M is important.

In the first direction of circulation, the first exchange zone 9a is reached first and therefore the temperature difference between the refrigerant and the first exchange zone 9a is maximum. When the coolant arrives at the second exchange zone 9b, the temperature difference between the coolant and the second exchange zone 9b is less and therefore the heat exchanges are also less. Conversely, in the second direction of traffic, it is the second exchange zone 9b is reached first and the first exchange zone 9a then. By alternating the directions of circulation it is therefore possible to homogenize the temperature at the level of the battery module.

It can thus be seen that the thermal management circuit 1 owing to the fact that it comprises a heat exchange device 9 allowing circulation in two distinct directions of circulation as well as its control process, allows homogeneous thermal management of the battery modules. M, particularly during rapid charging of the batteries where the cooling requirements are high and where good homogeneity of this cooling over the entire surface of the battery modules M is important.

Claims (11)

1. Thermal management circuit (1) of an electrical storage device (D) of a motor vehicle inside which a coolant circulates, the electrical storage device (D) comprising at least one battery module ( M), the thermal management circuit (1) comprising at least, in the direction of circulation of the refrigerant, a compressor (3), a first heat exchanger (5) intended to be traversed by an external air flow ( 100), a first expansion device (7) and at least one heat exchange device (9) disposed at each battery module (M), characterized in that the heat exchange device (9) comprises a distribution switch (11) for the coolant coming from the first expansion device (7) and at least a first heat exchange zone (9a) and a second heat exchange zone (9b) connected in series , said distribution switch (11) being configured so as to redirect the coolant first to the first heat exchange zone (9a) and recover the coolant at the outlet of the second heat exchange zone (9b) in a first direction of circulation, or to redirect the refrigerant first to the second heat exchange zone (9b) and recover the refrigerant at the outlet of the first exchange zone (9a) in a second direction of circulation. 2. Thermal management circuit (1) according to claim 1, characterized in that the heat exchange device (9) is a heat exchanger comprising a channel for circulation of the refrigerant fluid comprising branches of circulation against the current arranged in series, the first heat exchange zone (9a) corresponding to a first circulation branch and the second heat exchange zone (9b) corresponding to a second circulation branch. 3. Thermal management circuit (1) according to claim 1, characterized in that the heat exchange device (9) comprises, a plurality of heat exchangers, the first heat exchange zone (9a) corresponding to a first heat exchanger and the second heat exchange zone (9b) corresponding to a second heat exchanger. 4. Thermal management circuit (1) according to any one of claims 1 to 3, characterized in that the distribution switch (11) comprises: ° an inlet (lia) of coolant connected to the first expansion device (7), ° at least a first inlet-outlet (11c) of controllable coolant and connected to the first heat exchange zone (9a), ° a second inlet-outlet (1 Id) of controllable coolant and connected to the second heat exchange zone (9b), and ° an outlet (11b) of coolant through which the coolant having passed through the device heat exchange (9) is removed. 5. Thermal management circuit (1) according to claim 4, characterized in that the distribution switch is a four-way valve connected to the input (lia), to the output (Ub) as well as to the various inputs- coolant outlets (11b, 11c). 6. thermal management circuit (1) according to claim 4, characterized in that the distribution switch (11) comprises a plurality of connections connecting 1 input (lia) as well as the output (11b) with each of the input-outputs ( lld, 11c) of refrigerant, each of the connections comprising a controllable blocking means (110) of the refrigerant in order to define its destination. 7. thermal management circuit (1) according to any one of the preceding claims, characterized in that it comprises at least two battery modules (M) and at least two heat exchange devices (9) associated, said heat exchange devices (9) being connected in parallel with each other, the first expansion device (7) being common for said heat exchange devices (9). 8. Thermal management circuit (1) according to one of claims 1 to 6, characterized in that it comprises at least one primary branch (A) comprising the first expansion device (7) and the at least one device heat exchange (9) and at least one secondary branch (B) arranged in parallel with the at least one primary branch (A) and comprising, in the direction of circulation of the coolant, a second expansion device (13 ) and a second heat exchanger (15). 9. Thermal management circuit (1) according to claim 7, characterized in that it comprises at least one primary branch (A) comprising the first expansion device (7) and the at least two heat exchange devices ( 9) and at least one secondary branch (B) arranged in parallel with the at least one primary branch (A) and comprising, in the direction of circulation of the coolant, a second expansion device (13) and a second heat exchanger heat (15). 10. Thermal management circuit (1) according to one of claims 8 or 9, characterized in that it comprises on its primary branch (A), a third expansion device (21) disposed downstream of the device or devices heat exchange (9). 11. Method for controlling a thermal management circuit (1), said thermal management circuit (1) comprising at least, in the direction of circulation of the refrigerant, a compressor (3), a first heat exchanger (5 ) intended to be traversed by an external air flow (100), a first expansion device (7) and at least one heat exchange device (9) disposed at each battery module (M), according to any one of the preceding claims, said heat exchange device (9) comprising a distribution switch (11) for the coolant coming from the first expansion device (7) and at least one first heat exchange zone (9a) and a second heat exchange zone (9b) connected in series, said distribution switch (11) being configured so as to redirect the coolant first to the first heat exchange zone (9a) and recover fluid r refrigerant leaving the second exchange zone (9b) in a first direction of circulation, or redirecting the refrigerant first to the second heat exchange zone (9b) and recovering the refrigerant leaving the first exchange zone (9a) in a second direction of circulation, characterized in that said method comprises a cooling cycle of a battery module (M), said cooling cycle comprising a first cooling step during which the refrigerant flows in the first direction of circulation and a second cooling step during which the refrigerant circulates in the second direction of circulation.