Cooling method for automotive vehicle batteries.

Abstract

Cooling method. Cooling method for a motor vehicle battery, the vehicle comprising a body, a battery fixed under the body, and a fairing interposed between the battery and an airflow circulating under the vehicle, the fairing comprising at least one air intake, each at least one air intake being located upstream of the battery in the airflow, and each at least one air intake being equipped with at least one flap, the method comprising - a first mode in which at least one flap equipping at least one air intake is in the open position and allows airflow from outside the fairing to contact the battery, and - a second mode in which each flap equipping at least one air intake is in the closed position and prevents airflow from outside the fairing to contact the battery. Figure for the abstract: 2

Description

Title of the invention: Cooling method for a motor vehicle battery.

[0001] The invention relates to a cooling method for a motor vehicle battery. The invention also relates to a cooling device for a motor vehicle battery. The invention further relates to a motor vehicle equipped with such a cooling device. The invention also relates to a computer program implementing the mentioned method. The invention finally relates to a recording medium on which such a program is recorded.

[0002] In order to meet the objectives of reducing carbon dioxide emissions and optimizing vehicle consumption, fairing of the area located under the body is becoming increasingly common. The fairing advantageously reduces the SCx of the vehicle, thereby reducing its energy consumption.

[0003] However, in vehicles equipped with a traction battery, such a fairing limits the transfer of heat between the traction battery and an air flow circulating under the vehicle body. However, maintaining the temperature of the battery within an optimal operating range is essential. The management of the temperature of the battery is then mainly managed by an air conditioning device with a phase change fluid. The air conditioning device may be of the reversible heat pump type. However, such a device consumes energy, in particular for the operation of a compressor, thus leading to an increase in fuel consumption and an increase in carbon dioxide emissions by hybrid vehicles, as well as a reduction in the autonomy of hybrid or electric vehicles.

[0004] The aim of the invention is to provide a device and a method for cooling a motor vehicle battery which overcomes the drawbacks mentioned above and improves the devices and methods for cooling a motor vehicle battery known from the prior art. In particular, the invention makes it possible to produce a device and a method which are simple and reliable and which allow a reduction in fuel consumption and carbon dioxide emissions for hybrid vehicles and an increase in autonomy for electric or hybrid vehicles.

[0005] To this end, the invention relates to a cooling method for a motor vehicle battery, the motor vehicle comprising a body, a battery fixed under the body and a fairing interposed between the battery and an air flow circulating under the motor vehicle, the fairing comprising at least one air intake, each at least one air intake being located upstream of the battery in the air flow, and each at least one air intake being equipped with at least one flap, the method comprising - a first operating mode in which the at least one flap equipping the at least one air intake is in the open position and allows circulation of the air flow from outside the fairing in contact with the battery, and - a second operating mode in which each flap equipping the at least one air intake is in the closed position and prevents circulation of the air flow from outside the fairing in contact with the battery.

[0006] In one embodiment, at least one flap equipping the at least one air intake is placed in the open position if the following two conditions are verified: (i) a battery temperature is above a cooling start threshold, and (ii) a difference between the battery temperature and an outside air temperature is greater than a positive temperature difference.

[0007] In one embodiment, when the temperature of the battery reaches an end of cooling threshold, all the flaps equipping the at least one air intake are placed in the closed position when the temperature of the battery reaches the end of cooling threshold, the end of cooling threshold taking a first value if intensive use of the battery is in progress and / or if a next rapid recharge of the battery is planned, and the end of cooling threshold taking a second value otherwise, the first value being less than the second value.

[0008] In one embodiment, the cooling method comprises a first step comprising - a determination of a first indicator of intensive use of the battery, and a determination of a second indicator of a next rapid recharge of the battery planned by the driver, - an assignment of a first value to a cooling start threshold and an assignment of a second value to a cooling stop threshold if the first or second indicator is true, or an assignment of a third value to the cooling start threshold and an assignment of a fourth value to the cooling stop threshold if the first and second indicators are false, the third value being greater than the first value, and the fourth value being greater than the second value, then - a comparison of a battery temperature at the cooling start threshold, and a measurement of a temperature of air outside the motor vehicle. In addition, the first step is followed - a second step implementing the first operating mode only if the battery temperature is higher than the cooling start threshold, and if a difference between the battery temperature and the outside air temperature is higher than a minimum positive temperature difference, or - a third step implementing the second operating mode only if the battery temperature is higher than the cooling start threshold and if the difference between the battery temperature and the outside air temperature is lower than the minimum positive temperature difference.

[0009] In one embodiment, the vehicle comprises an additional air conditioning means for the battery, and the additional air conditioning means is used when performing the third step. In addition, when performing the second step, the additional air conditioning means is used only if a temporal variation in temperature of the battery is greater than a given variation threshold, for example zero degrees per second.

[0010] The invention further relates to a cooling device for a battery of a motor vehicle, the vehicle comprising a body under which the battery is fixed, a fairing fixed to the body, a temperature sensor of air outside the vehicle, a battery temperature sensor, a computer, a network connecting the computer to a set of computers and an air conditioning compressor, the device comprising hardware and / or software elements implementing the method according to the invention.

[0011] In one embodiment of the device, the respective flaps of each at least one air intake have a common axis of rotation oriented in a transverse direction of the motor vehicle.

[0012] In one embodiment of the device, each at least one air intake is a NACA air intake, of which - an air intake length is measured in a longitudinal direction of the motor vehicle between an air inlet into the air intake and an air outlet from the air intake, - an air intake width is measured in a transverse direction of the motor vehicle at the level of the air outlet of the air intake, Furthermore, the ratio of the air intake length to the air intake width is within an optimal value range for achieving laminar air flow in the air intake, the optimal value range being, for example, between 1.6 and 2.

[0013] In one embodiment of the device, the fairing comprises at least two NACA air intakes of identical shapes and dimensions and distributed uniformly in the transverse direction of the motor vehicle. In addition, the number and dimensions of NACA air intakes required to cool the entire battery are calculated based on - a width of the battery measured in the transverse direction of the motor vehicle, and - of a given dimension according to the longitudinal direction of a fairing area available for the installation of air intakes, the available fairing area being located between the battery and a front axle of the motor vehicle.

[0014] The invention further relates to a vehicle comprising a cooling device according to the invention.

[0015] The invention also relates to a computer program product comprising program code instructions recorded on a computer-readable medium for implementing the steps of the method according to the invention, or to a computer program product downloadable from a communication network and / or recorded on a data medium readable by a computer and / or executable by a computer, comprising instructions which, when the program is executed by the computer, lead the latter to implement the method according to the invention.

[0016] The invention also relates to a computer-readable data recording medium on which is recorded a computer program comprising program code instructions for implementing the method according to the invention, or to a computer-readable recording medium comprising instructions which, when executed by a computer, cause the latter to implement the method according to the invention.

[0017] The attached drawing represents, by way of example, an embodiment of a determination device according to the invention and an embodiment of a determination method according to the invention.

[0018] [Fig.l] represents a motor vehicle equipped with an embodiment of a cooling device according to the invention.

[0019] [Fig.2] is a bottom view of a motor vehicle equipped with a mode of production of the cooling device according to the invention.

[0020] [Fig. 3] is a top view of one embodiment of the cooling device development according to the invention.

[0021] [Fig.4] is a top view of the cooling device according to the invention controlled according to a first operating mode.

[0022] [Fig. 5] is a bottom view of the cooling device according to the invention controlled according to the first operating mode.

[0023] [Fig.6] is a top view of the cooling device according to the invention controlled according to a second operating mode.

[0024] [Fig.7] is a bottom view of the cooling device according to the invention controlled according to the second operating mode.

[0025] [Fig.8] is a schematic representation of a network connecting a set of computers of the motor vehicle equipped with the invention.

[0026] [Fig.9] is a first flowchart of a cooling method according to the invention.

[0027] [Fig. 10] illustrates an embodiment of a first and a second cooling profile.

[0028] [Fig. 11] is a second flowchart of the cooling method according to the invention.

[0029] An example of a motor vehicle 100 equipped with an embodiment of a battery cooling device is described below with reference to [Fig.l].

[0030] The motor vehicle 100 is a hybrid or electric vehicle equipped with a traction battery 1, called battery 1. The motor vehicle 100 may be a vehicle of any type, for example a passenger or utility vehicle or a public transport vehicle.

[0031] In addition to the battery 1, the motor vehicle 100 comprises - a box 2 under which the battery 1 is fixed, - a fairing 3 fixed to the body 2, - a sensor 4 for the temperature of air outside the vehicle, - a battery temperature sensor 5, - a computer 6 (or electronic control unit 6) monitoring the temperature of the battery 1 and controlling the opening and closing of flaps 32 arranged on the fairing 3, - a network 7 connecting the computer 6 to a set 8 of computers described below, and - a compressor 9 of a cooling circuit of the motor vehicle 100.

[0032] As illustrated by [Fig.2], which represents the motor vehicle 100 in a view from below, the fairing 3 is fixed so as to be interposed between an air flow 200 circulating under the motor vehicle 100 and the battery 1. In other words, the fairing 3 isolates the battery 1 from an air flow 200 circulating under the motor vehicle 100.

[0033] The battery 1 is arranged in an underbody area located between a front axle 102 and a rear axle 103 of the motor vehicle 100.

[0034] The motor vehicle 100 has a longitudinal axis X directed towards the rear of the vehicle, and a transverse axis Y, perpendicular to the longitudinal axis X, and an axis vertical Z oriented towards the top of the vehicle, the X, Y, Z axes together forming a direct orthonormal reference frame (X, Y, Z).

[0035] The fairing 3 comprises at least one air inlet 31, or air intake 31. As is more specifically visible in [Fig. 3], each air intake 31 is located upstream of the battery 1 (the battery 1 is shown in transparency in [Fig. 3]) relative to the direction of the longitudinal axis X, and each air intake 31 is equipped with a flap 32.

[0036] An embodiment of an air intake 31 is represented more specifically by Figures 4 to 7. An air intake has a length 311, measured along the longitudinal direction X of the vehicle, and a width 312, measured along the transverse direction Y of the vehicle. In a preferred embodiment, the width of the air intake is progressive along the longitudinal axis X and the width 312 is measured at the widest end of the air intake 31. In this embodiment, the width of the air intake increases along the direction of the longitudinal axis X.

[0037] In a preferred embodiment, each air intake 31 is a NACA type air intake, the term "NACA" being the acronym for "National Advisory Committee for Aeronautics". A NACA type air intake is a common form of air intake having low drag. Advantageously, a NACA type air intake has a specific aerodynamic profile allowing a laminar flow of air in the air intake to be obtained.

[0038] In this embodiment, the quotient between the air intake length 311 and the air intake width 312 is within an optimal value range for obtaining a laminar air flow in the air intake 31, the optimal value range being for example between 1.6 and 2. In addition, the slope of the air intake 31, i.e. the maximum variation slope, along the longitudinal axis X, of a height of the air intake 31 measured along the axis Z, is advantageously between 5 and 7 degrees.

[0039] In this embodiment, the at least one air intakes have the same dimensions. The number of air intakes 31 and the dimensions of the air intakes are then determined by taking into account the range of optimal values ​​relating to the quotient between the length and the width of an air intake 31 of the NACA type, but also the transverse dimension 11 of the battery 1 and a given dimension 36 in the longitudinal direction X of an available fairing zone 37 for the installation of air intakes, the available fairing zone 37 being located between the battery 1 and a front axle 102 of the motor vehicle.

[0040] In other words, the number of air intakes 31 and their longitudinal and transverse dimensions 311, 312 are calculated as a function of the space available 37 to create air intakes in the fairing part located upstream of the battery. This calculation also takes into account an optimum quotient (i.e. within the range of optimum values) between the longitudinal and transverse dimensions 311, 312 of the air intakes, and the need to cool the battery over its entire width 11.

[0041] The air flow 200, circulating under the motor vehicle 100 in the longitudinal direction X, enters the air intake 31 through a first end 313, and moves to a second end 314 materialized by an opening, called opening 314.

[0042] A rear opening 38 is arranged in the rear part of the fairing 3 and downstream of the battery 1, in order to allow the extraction of the air flow 200 downstream of the battery 1. Advantageously, the surface area of ​​the rear opening 36 is greater than the sum of the surface areas of the air inlets 314. For example, the surface area of ​​the rear opening 38 is 1.2 to 1.5 times greater than the sum of the surface areas of the air inlets 314.

[0043] In one embodiment, the opening 38 is never closed. Alternatively, the opening 38 could be equipped with a shutter allowing it to be closed. The shutter could be controlled to open and close synchronously with the shutters 32 of the air intakes 31.

[0044] Each opening 314 is equipped with a flap 32 which can take two positions, a first position called open (represented by figures 4 and 5) and a second position called closed (represented by figures 6 and 7). In one embodiment, a flap 32 in the open position is located in a plane parallel to the plane (X, Y), and a flap 32 in the closed position is located in a plane parallel to the plane (Y, Z).

[0045] When a flap 32 is in the open position, it allows circulation of the air flow 200 in contact with the battery 1 located above the fairing 3. When a flap 32 is in the closed position, it prevents circulation of the air flow 200 in contact with the battery 1.

[0046] As shown in Figures 3 to 7, advantageously the flap 32 equipping each at least one air intake 31 is movable in rotation around an axis 33 oriented in the transverse direction Y of the motor vehicle 100.

[0047] Furthermore, when the fairing has several air intakes 31, the respective flaps 32 of each air intake 31 advantageously share a common axis of rotation 35 oriented in a transverse direction Y of the motor vehicle. In other words, the respective axes of rotation of the flaps 32 are the same.

[0048] In one embodiment, by means of a single electric motor 34, the common rotation axis 35 also makes it possible to control in a coordinated manner the flaps 32 of the air intakes 31 to place them simultaneously either in the open position or in the closed position.

[0049] In alternative embodiments, each shutter 32 could be controlled independently, in particular by separate motors 34, so as to open or close independently of each other and thus allow cooling. selective of a portion of the battery, but also allow for less degradation of the SCx when only part of the shutters are in the open position.

[0050] In a preferred embodiment, the electric motor 34 is controlled by the BMS 6 (“BMS” being the acronym for “Battery Management System”), which manages the operation of the battery 1. In an alternative embodiment not described in this document, the motor 34 could be controlled by a computer separate from the BMS 6. In the remainder of the document, the computer controlling the electric motor 34 is called “computer 6”.

[0051] The computer 6 is notably connected to the temperature sensor 5 which provides a measurement of the temperature T_bat of the battery 1.

[0052] In one embodiment, the computer 6 is further connected to the network 7. The network 7 is also called the “CAN” network (acronym “Controller Area Network”). As described in [Fig. 8], the computer 6 is connected to a set 8 of computers, via the network 7.

[0053] The computer 6 comprises a microprocessor 61, a local electronic memory 62 and communication interfaces 63 allowing the microprocessor 61 to communicate with the engine 34 and the set 8 of computers via the network 7.

[0054] The set 8 of computers comprises an air conditioning computer 81, which provides an outside temperature T_ext measured outside a passenger compartment of the motor vehicle 1. The computer 81 controls the starting and stopping of a compressor 9 of a battery cooling system.

[0055] The set 8 of computers also comprises a computer 82 which controls the longitudinal speed of the vehicle, and transmits on the network 7 a current value of the longitudinal speed V_long of the motor vehicle 1.

[0056] The set 8 of computers further comprises a computer 83 which manages the navigation data of the motor vehicle 100, in particular an indicator of a forthcoming rapid recharge of the vehicle Ind_RR. The computer 83 shares the indicator Ind_RR on the network 7. In the case where the indicator Ind_RR is true, the computer 6 is thus informed that the temperature of the battery 1 must be brought back into a low temperature range, as will be detailed later in this document.

[0057] The set 8 of computers further comprises a computer 84 which is connected to a switch 10 managing the activation of a sporty driving mode of the motor vehicle 100. The computer 84 shares an indicator of an intensive driving mode Ind_I on the network 7. In the case where the indicator Ind_I is true, the computer 6 is thus informed that the temperature of the battery must be brought back into a low temperature range.

[0058] The network 7 thus allows the computer 6 to access measurements carried out by the computers of the set 8 and to record said measurements in the local memory. 62. The measurements carried out by the computers of the set 8 and stored in the local memory 62 advantageously include an outside temperature T_ext, a longitudinal speed of the vehicle V_long, an indication of rapid recharging of the vehicle Ind_RR, and an indication of an intensive driving mode Ind_I.

[0059] The network 7 further allows the computer 6 to transmit, to the engine 34, orders to open and close at least one flap 32.

[0060] The network 7 also allows the computer 6 to send orders to the computer 81 to activate or stop the compressor 9.

[0061] In one embodiment, the microprocessor 61 makes it possible to execute software comprising the following modules, which collaborate with each other: - a module 610 for determining a cooling mode, which collaborates with the memory 62, - a control module 611 according to a first operating mode, which collaborates with the memory 62, the motor 34 and the compressor 9, and - a control module 612 according to a second operating mode, which collaborates with the memory 62 and the compressor 9.

[0062] The motor vehicle 100, in particular the cooling system, preferably comprises all the hardware and / or software elements configured so as to implement the method defined in the subject of the invention or the method described below.

[0063] A first mode of execution of a cooling method is described below with reference to [Fig.9].

[0064] The cooling method comprises: - a second step El 1 of control according to a first operating mode in which the at least one flap 32 equipping the at least one air intake 31 is in the open position and allows circulation of the air flow 200 from the outside of the fairing 3 in contact with the battery 1, and - a third step E12 of control according to a second operating mode in which all the flaps 32 equipping the at least one air intake 31 are in the closed position and prevent circulation of the air flow 200 from outside the fairing 3 in contact with the battery 1.

[0065] Upstream of the second and third steps E11, E12, in a first step E10, a cooling mode to be applied to the at least one flap 32 is determined.

[0066] For this purpose, step E10 comprises: - a determination of a first indicator Ind_I of intensive use of battery 1, and a determination of a second indicator Ind_RR of a next rapid recharge of the battery planned by the driver, - an assignment of a first value T_start_cooling_A to a cooling start threshold and an assignment of a second value T_stop_cooling_A to a cooling stop threshold if the first or second flag is true, or an assignment of a third value T_start_cooling_B to the cooling start threshold and an assignment of a fourth value T_stop_cooling_B to the cooling stop threshold if the first and second flags are false, the third value T_start_cooling_B being greater than the first value T_start_cooling_A, and the fourth value T_stop_cooling_B being greater than the second value T_stop_cooling_A Then - a comparison of a temperature T_bat of battery 1 to the cooling start threshold, and - a measurement of a temperature T_ext of air outside the motor vehicle (100).

[0067] Then, the first step E10 is followed by - the second step Eli only if the battery temperature T_bat is higher than the cooling start threshold T_start_cooling_A, T_start_cooling_B, and if a difference AT between the battery temperature T_bat and the outside air temperature T_ext is higher than a minimum positive temperature difference AT_min, or - the third step E12 only if the battery temperature T_bat is higher than the cooling start threshold T_start_cooling_A, T_start_cooling_B and if the difference AT between the battery temperature T_bat is lower than the minimum positive temperature difference AT_min.

[0068] In one embodiment, AT_min may be equal to a few degrees, for example 5°C.

[0069] The different sub-steps of the first step E10 are detailed below.

[0070] At the start of the first step E10, the flaps 32 are in the closed position.

[0071] In a first sub-step E101 of step E10, a cooling profile is determined PI, P2 to be applied to battery 1.

[0072] For this, we test - a current value, stored in the local memory 62, of the indicator of an intensive driving mode Ind_I on the one hand, and - a current value, stored in local memory 62, of the vehicle's fast charging indicator Ind_RR on the other hand.

[0073] If one of these indicators is true, then the cooling profile is determined to be of a first type PI. Otherwise, the cooling profile is determined to be of a second type P2.

[0074] [Fig. 10] illustrates an embodiment of the first and second types of cooling profiles PI and P2. The y-axis of the graph represents two states of the battery cooling: an E_ON state in which the battery is cooled, and an E_OFF state in which the battery is not cooled.

[0075] The first type of cooling profile PI is applied in driving phases requiring the temperature T_bat of the battery 1 to be maintained in a first range of low temperatures, with a lower limit T_stop_cooling_A, and an upper limit T_start_cooling_A.

[0076] For example, - the threshold T_stop_cooling_A, below which the vehicle cooling is stopped, can be set to 25°C, and - the threshold T_start_cooling_A, above which the vehicle cooling is started, can be set to 35°C.

[0077] Thus, if at least one of the indicators of an intensive driving mode Ind_I or rapid charging of the vehicle Ind_RR is true, then the temperature of the battery 1 will be maintained between 25°C and 35°C.

[0078] If the motor vehicle is not in an intensive driving mode and if no rapid recharging of the vehicle is planned in the short term, then the second type of cooling profile P2 is applied. For example, the temperature of the battery 1 is preferentially maintained in a second temperature range located between a threshold T_stop_cooling_B equal to 30°C, and a threshold T_start_cooling_B equal to 40°C.

[0079] The selected cooling profile PI, P2 makes it possible to determine a temperature range applicable to the temperature of battery 1, delimited by a minimum temperature T_stop_cooling_A and a maximum temperature T_start_cooling_A.

[0080] Then, in a second sub-step E102 of step E10, the position of the current temperature of the battery T_bat relative to the applicable temperature range is determined.

[0081] As long as the current temperature T_bat is lower than the temperature T_start_cooling_A, then cooling of the battery is not desirable, and we return to sub-step E101 of determining a cooling profile.

[0082] If the current temperature T_bat is higher than the temperature T_start_cooling_A, in a third sub-step E103 of step E10, the temperature of the battery T_bat is compared to the temperature T_ext of air outside the motor vehicle 100.

[0083] The outside air temperature T_ext is updated regularly in the local memory 62. Similarly, the current battery temperature T_bat is updated regularly in the local memory 62 from the data from the sensor 5.

[0084] In one embodiment, the outside air can be used to cool the battery 1 only if the difference AT between the battery temperature T_bat and the outside temperature T_ext is greater than a minimum positive temperature difference AT_min, for example 5°C, or 3°C. In this case, we continue with step El 1 of controlling the shutters according to the first operating mode, in which the shutters are in the open position. Otherwise, we continue with step E12 of controlling the shutters according to the second operating mode, in which the shutters 32 are in the closed position.

[0085] In step E11, in particular in a first sub-step E11 of step E11, an order to open the flaps 32 is transmitted to the motor 34.

[0086] Then we continue with a loop comprising a second and third sub-steps E112, E113.

[0087] In sub-step E1 12, it is tested whether the current temperature of the battery T_bat is lower than the temperature T_stop_cooling_A. If this is the case, then cooling the battery is no longer desirable. An order to close the flaps 32 is then transmitted to the motor 34 and the process loops back to step E10.

[0088] If the current temperature T_bat is higher than the temperature T_stop_cooling_A, then the cooling of battery 1 must be continued.

[0089] We then continue with sub-step El 13, in which we test whether the temperature of the battery T_bat is decreasing. For this purpose, in a preferred embodiment, the local memory 62 stores a measurement of variation Var_T_bat of the temperature of the battery 1, calculated from the most recent measurements of the temperature of the battery. The sign of the variation Var_T_bat makes it possible to indicate whether the temperature of the battery is increasing or decreasing.

[0090] If the rate of variation Var_T_bat of the battery temperature is lower than a given threshold Var_T_req, this threshold being zero or negative, this means that the cooling implemented meets the current needs of the vehicle. We then loop back to step El 12.

[0091] As a note, the Var_T_req threshold could be modified depending on the vehicle's usage conditions, for example, if an upcoming recharge is planned, or when the driving mode is sporty.

[0092] If the rate of variation Var_T_bat of the battery temperature is greater than the given negative threshold Var_T_req, this means that the cooling currently implemented does not meet the current needs of the motor vehicle 100. Additional air conditioning means must then be implemented, in particular the air conditioning compressor 9 can be started to cool the battery more quickly.

[0093] To this end, we then continue with a sub-step El 14 in which a start-up order is transmitted to the compressor 9 via the computer 81.

[0094] We then iterate on a sub-step El 15 of comparing the temperature of the battery T_bat with the temperature T_stop_cooling_A, until the temperature of the battery T_bat reaches a value less than or equal to the temperature T_stop_cooling_A.

[0095] Then, in a sub-step El 16, a stop order is transmitted to the compressor 9 and an order to close the flaps 32 to the motor 34.

[0096] We then loop back to step E10.

[0097] Step E12 implements cooling of the battery 1 by activating the compressor 9 and without opening the flaps 32.

[0098] It comprises a sub-step E121 in which a start-up order is transmitted to the compressor 9 via the computer 81.

[0099] We then iterate on a sub-step E122 of comparing the temperature of the battery T_bat with the temperature T_stop_cooling_A, until the temperature of the battery T_bat reaches a value less than or equal to the temperature T_stop_cooling_A.

[0100] Then, in a sub-step E123, a stop order is transmitted to the compressor 9 via the computer 81.

[0101] We then loop back to step E10.

[0102] Thus, the additional air conditioning means or compressor 9 is used - when executing the third step E12, i.e. when the outside temperature T_ext is higher than the battery temperature T_bat, or - when executing the second step Eli, only if the temperature variation over time Var_T_bat of battery 1 is greater than a given variation threshold, for example zero degrees per second.

[0103] A second mode of carrying out a cooling method is described below with reference to [Fig. 11].

[0104] In a first step IF the flaps 32 are in the closed position.

[0105] Then, in a second step S2, we test whether a rapid charge of the vehicle is planned or if heavy battery usage is in progress: - if not, in a third step S3, we use standard battery cooling thresholds, corresponding to the cooling profile P2 (represented by [Fig. 10]), then we continue with a fifth step S5, - if yes, in a fourth step S4 we reduce the temperature thresholds, thus obtaining the temperature profile PI (represented by [Fig. 10]) then we continue with the fifth step S5.

[0106] In the fifth step S5, it is tested whether the temperature of the battery T_bat is higher than the cooling start threshold determined in step S3 or S4: - if not, we loop back upstream of step S2, - if yes, we move on to a sixth stage S6.

[0107] In the sixth step S6, we test whether the temperature of the battery T_bat is higher than the temperature of the air outside the vehicle: - if yes, we continue with a seventh stage S7, - if not, we continue with an eleventh step IF 1.

[0108] In the seventh step S7, an order to open the flaps 32 is sent to the motor 34, then an eighth step S8 is carried out.

[0109] In the eighth step S8, we test whether the temperature of the battery T_bat is lower than the cooling stop threshold determined in one of the steps S3 or S4: - if yes, we continue with a step S9, in which we send an order to close the flaps 32 to the motor 34, then we loop back upstream of the second step S2, - if no, we continue with a tenth step S10.

[0110] In the tenth step S10, it is tested whether the temperature of the battery has increased: - if yes, we continue with the eleventh step IF 1, - if yes, we loop back upstream of the eighth step S8.

[0111] In the eleventh step SI 1, a start command is sent to the air conditioning compressor 9 to activate the cooling of the battery by a cooling fluid.

[0112] Then, we loop on a twelfth step S12 as long as the temperature of the battery T_bat is higher than the cooling stop threshold determined in one of the steps S3 or S4.

[0113] Then, we move on to a thirteenth step S13 in which we send a stop order to the air conditioning compressor 9.

[0114] We then move on to a fourteenth step S14 in which we test whether the flaps 32 are in the open position: - if yes, we continue with the tenth step S10, in which we send an order to close the flaps 32 to the motor 34, then we loop back upstream of the second step S2, - if not, we loop back upstream of the second step S2.

[0115] More generally, according to one embodiment, one switches between the first and second operating modes according to the following logic.

[0116] At least one flap 32 equipping the at least one air intake 31 is placed in the open position if the following two conditions are verified: (i) a battery temperature T_bat is higher than a first cooling start threshold T_start_cooling_B, and (ii) if a difference between the battery temperature T_bat and an outside air temperature T_ext is greater than a positive temperature difference AT_min.

[0117] In addition, advantageously, when the battery temperature reaches an end of cooling threshold T_stop_cooling_A, T_stop_cooling_B, all the flaps 32 equipping the at least one air intake 31 are placed in the closed position when the battery temperature reaches the end of cooling threshold, the end of cooling threshold taking a first value if intensive use of battery 1 is in progress and / or if a next rapid recharge of the battery is planned, and the end of cooling threshold taking a second value otherwise, the first value being lower than the second value.

[0118] Finally, the method for cooling a battery according to the invention makes it possible to benefit from the aerodynamic advantages of a fairing fixed under the body of a motor vehicle, while maintaining the possibility of bringing a flow of air from the outside of the fairing to the inside of the fairing in contact with the battery during specific driving phases where cooling the battery is essential.

[0119] When the shutters are in the closed position, the cooling device according to the invention thus makes it possible to preserve an SCx compatible with current constraints on reducing carbon dioxide emissions.

[0120] Furthermore, in the phases where the flaps are in the open position to direct an air flow towards the battery, the cooling device according to the invention can totally or partially replace a conventional battery air conditioning system consuming electricity. This technical solution thus makes it possible to save electrical energy, which results in a reduction in fuel consumption and carbon dioxide emissions for hybrid vehicles or an increase in autonomy for electric or hybrid vehicles.

Claims

Claims

1. Cooling method for a motor vehicle battery, the motor vehicle (100) comprising a body (2), a battery (1) fixed under the body (2) and a fairing (3) interposed between the battery (1) and an air flow (200) circulating under the motor vehicle (100), the fairing comprising at least one air intake (31), each at least one air intake being located upstream of the battery (1) in the air flow (200), and each at least one air intake being equipped with at least one flap (32), characterized in that the method comprises - a first operating mode in which the at least one flap (32) equipping the at least one air intake (31) is in the open position and allows circulation of the air flow (200) from outside the fairing (3) in contact with the battery (1),and - a second operating mode in which each flap (32) equipping the at least one air intake (31) is in the closed position and prevents circulation of the air flow (200) from outside the fairing (3) in contact with the battery (1).,

2. Cooling method according to the preceding claim, characterized in that at least one flap (32) equipping the at least one air intake (31) is placed in the open position if the following two conditions are satisfied: (i) a temperature of the battery (T_bat) is greater than a cooling start threshold (T_start_cooling_A, T_start_cooling_B), and (ii) a difference between the temperature of the battery (T_bat) and a temperature of an outside air (T_ext) is greater than a positive temperature difference (AT_min).

3. Cooling method according to the preceding claim, characterized in that, when the temperature of the battery reaches an end of cooling threshold (T_stop_cooling_A, T_stop_cooling_B), all the flaps (32) equipping the at least one air intake (31) are placed in the closed position when the temperature of the battery reaches the end of cooling threshold, the end of cooling threshold taking a first value if intensive use of the battery (1) is in progress and / or if a next rapid recharge of the battery is planned, and

4. the end of cooling threshold taking a second value otherwise, the first value being lower than the second value. Cooling method according to one of the preceding claims, characterized in that it comprises a first step (E10) comprising • a determination of a first indicator (Ind_I) of intensive use of the battery (1), and a determination of a second indicator (Ind_RR) of a next rapid recharge of the battery planned by the driver, • an assignment of a first value (T_start_cooling_A) to a cooling start threshold and an assignment of a second value (T_stop_cooling_A) to a cooling stop threshold if the first or second indicator is true, or an assignment of a third value (T_start_cooling_B) to the cooling start threshold and an assignment of a fourth value (T_stop_cooling_B) to the cooling stop threshold if the first and second indicators are false, the third value (T_start_cooling_B) being greater than the first value (T_start_cooling_A), and the fourth value (T_stop_cooling_B) being greater than the second value (T_stop_cooling_A), then • a comparison of a temperature (T_bat) of the battery (1) to the cooling start threshold (T_start_cooling_A, T_start_cooling_B), and • a measurement of a temperature (T_ext) of air outside the motor vehicle (100), and in that the first step (E10) is followed • a second step (Eli) implementing the first operating mode only if the battery temperature (T_bat) is higher than the cooling start threshold (T_start_cooling_A, T_start_cooling_B), and if a difference (AT) between the battery temperature (T_bat) and the outside air temperature (T_ext) is higher than a minimum positive temperature difference (AT_min), or • a third stage (El2) implementing the second operating mode only if the temperature of the battery temperature (T_bat) is greater than the cooling start threshold (T_start_cooling_A, T_start_cooling_B) and if the difference (AT) between the battery temperature (T_bat) and the outside air temperature (T_ext) is less than the minimum positive temperature difference (AT_min).

5. Cooling method according to the preceding claim, the vehicle comprising an additional air conditioning means (9) for the battery, characterized in that the additional air conditioning means (9) is used during the execution of the third step (E12) and in that, during the execution of the second step (Eli), the additional air conditioning means (9) is used only if a temporal variation in temperature (Var_T_bat) of the battery (1) is greater than a given variation threshold, for example zero degrees per second.

6. Cooling device for a battery (1) of a motor vehicle (100), the vehicle comprising a body (2) under which the battery (1) is fixed, a fairing (3) fixed to the body (1), a temperature sensor (4) of air outside the vehicle, a battery temperature sensor (5), a computer (6), a network (7) connecting the computer (6) to a set (8) of computers and an air conditioning compressor (9), the device comprising hardware and / or software elements (1, 2, 3, 4, 5, 6, 7, 8, 9, 31, 32, 33, 34, 35, 36, 37, 38, 61, 62, 63, 81, 82, 83, 84, 610, 611, 612) implementing the method according to one of claims 1 to s

7. id J. Cooling device according to the preceding claim, characterized in that the respective flaps (32) of each at least one air intake (31) have a common axis of rotation (35) oriented in a transverse direction (Y) of the motor vehicle.

8. Cooling device according to claim 6 or 7, characterized in that each at least one air intake (31) is a NACA air intake, of which - an air intake length (311) is measured in a longitudinal direction (X) of the motor vehicle (100) between an air inlet (313) in the air intake and an air outlet (314) from the air intake, - an air intake width (312) is measured in a transverse direction (Y) of the motor vehicle (100) at the air outlet (314) from the air intake, and in that the quotient between the air intake length (311) and the air intake width (312) lies within an optimal value range for achieving laminar air flow in the air intake, the optimal value range being for example between 1.6 and 2.

9. Cooling device according to any one of the preceding claims, characterized in that the fairing (3) comprises at least two NACA air intakes (31) of identical shapes and dimensions and distributed uniformly in the transverse direction (Y) of the motor vehicle, and in that the number and dimensions of the NACA air intakes necessary to cool the entire battery (1) are calculated according to - a width (11) of the battery (1) measured in the transverse direction (Y) of the motor vehicle (100), and - of a given dimension (36) in the longitudinal direction (X) of an available fairing zone (37) for the installation of air intakes, the available fairing zone (37) being located between the battery (1) and a front axle (102) of the motor vehicle.

10. Vehicle characterized in that it comprises a cooling device according to any one of claims 6 to 9.

Images