Abstract:
The invention relates to a device for cooling the heat engine ( 10 ), electrical components ( 26, 14, 28 ), and an electrical power storage means (18) of a hybrid vehicle, said device including a first circuit ( 60,  HT) for cooling the heat engine, a second circuit (BT) for cooling the electrical components, and a third circuit ( 78,  TBT) for cooling the electrical power storage means, a heat transfer fluid being capable of flowing inside said circuits, comprising heat exchdange means ( 46, 48, 52 ). According to the invention, the heat exchange means consist of a heat exchanger ( 88 ) that is separated into three portions, and the device comprises a means for placing the first circuit in communication with the third circuit, the means being actuated on the basis of the temperature of the heat transfer fluid and on the basis of the flow of the heat transfer fluid inside the first circuit. The invention also relates to radiator for a hybrid vehicle.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is the US National stage, under 35 U.S.C. §371, of International App. No. PCT/FR2010/051956 which was filed on Sep. 21. 2010 and claims the priority of French application 0957165 filed on Oct. 13, 2009 the content of which (text, drawings and claims) is incorporated here by reference. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
       [0002]    Not Applicable. 
       BACKGROUND 
       [0003]    The present invention relates to a cooling device for a hybrid vehicle, comprising an internal combustion engine coupled to an electrical machine, and a device for storing electrical energy, such as a battery. The cooling of the different electrical components, the electrical energy storage device, and the combustion engine is ensured by a heat transfer fluid circulating through thermal heat exchangers. The invention also relates to a radiator for installation in a hybrid vehicle. 
         [0004]    For clarity purposes, the electrical energy storage device will be referred to in the specification simply by the term “battery”. However, the storage device can include, for example, several batteries and/or several super capacitors. A hybrid vehicle normally uses a supplementary battery dedicated to supplying electricity to the electric motor. The storage capacity is much larger than that of the normal battery. As a result, the battery has a tendency to heat up because it is used more than in a vehicle with only a combustion engine. The battery operates optimally in a well-defined temperature range, generally about 40° C. However, cooling is necessary to maintain a temperature of about 40° C. For this purpose, cooling with air, a heat transfer fluid, or a coolant can be used. In the case of a heat transfer fluid or coolant, a cooling circuit is used having a heat exchanger, such as a radiator, for circulation of the heat transfer fluid or coolant. 
         [0005]    Other electrical components of the vehicle also need to be cooled, such as the electrical traction motor(s) or the inverter, to operate in an optimal temperature range, generally about 60° C. Another cooling circuit having a heat exchanger is used for this purpose. 
         [0006]    Similarly, the combustion engine needs to be cooled for operation in a typical temperature range, generally about 80° C. Another cooling circuit having a heat exchanger is used for this purpose. 
         [0007]    In general, three cooling circuits having three heat exchangers are used with each cooling circuit operating in a different temperature range. While this configuration optimizes the cooling, it requires the addition of heat exchangers and the creation of independent cooling circuits. Therefore, it would be very advantageous to reduce the number of heat exchangers and, generally, to modify the cooling circuits for reduction of the cost and the space occupied under the hood of the vehicle. 
         [0008]    Vehicles equipped with climate control can also use the cooling fluid of the climate control circuit. However, as discussed above, such a configuration requires a dedicated cooling circuit. In addition, this configuration generates higher energy consumption due to the operation of a climate control compressor. 
         [0009]      FIG. 1  illustrates the most widely used prior art configuration using independent cooling circuits for circulation of a heat transfer fluid, which demonstrates the disadvantages of the prior art. 
       SUMMARY 
       [0010]    According to the present invention, when the battery is cooled by a heat transfer fluid, the use of a heat exchanger is shared between the combustion engine and the battery according to the operating conditions of the vehicle. The invention takes advantage of the fact that the elements to be cooled generally do not function at the same time, and therefore do not require cooling at the same time. For example, when the combustion engine runs, the electrical traction motor is stopped, and vice versa. Therefore, one of the goals of the invention is to use only one radiator and to share as much as possible the components already present under the hood of a hybrid motor vehicle, such as a motor-ventilator group and a degassing box for filling. For this purpose, the cooling device of the present invention uses a single heat exchanger divided in three members. In addition, the present invention comprises a device for directing the flow of heat transfer fluid from one cooling circuit to another. 
         [0011]    More specifically, the present invention relates to a device for cooling the combustion engine, the electric components, and the electrical energy storage device of a hybrid vehicle. The device includes a first circuit for cooling the combustion engine, a second circuit for cooling the electrical components, and a third circuit for cooling the electrical energy storage device, whereby a heat transfer fluid flows through the circuits which include heat exchange device. According to the invention, the heat exchange device includes a heat exchanger divided into three members: a high temperature member HT connected to the first circuit, a low temperature member BT connected to the second circuit, and a very low temperature member TBT connected to the third circuit. 
         [0012]    In addition, the device includes a device for establishing communication between the first circuit and the third circuit, which are located upstream and downstream of the member HT of the heat exchanger. The communication device located downstream actuates as a function of the temperature of the heat transfer fluid at the location of the communication device and the communication device located upstream are actuated in function of the flow of the heat transfer fluid through the first circuit. 
         [0013]    According to one embodiment, the communication device located between the first circuit and the third circuit and located upstream of the heat exchanger includes a double acting valve for closing the first circuit to allow the passage of heat transfer fluid from the third circuit to the member HT of the heat exchanger when the flow of heat transfer fluid in the first circuit is less than a predetermined flow. The communication device located between the first circuit and the third circuit and located downstream of the heat exchanger includes a double acting thermostatic valve for closing the first circuit to allow the passage of heat transfer fluid from the first circuit to the third circuit when the temperature of the heat transfer fluid at the location of the thermostatic valve is lower than the optimal operating temperature of the electrical energy storage device. 
         [0014]    The first circuit includes a water pump, a water outlet box in communication with a pump, and an air heater for heating the vehicle cabin and in communication with the inlet of the member HT of the heat exchanger through the intermediary of a conduit connected between the outlet of the water outlet box and the inlet of the member HT. The conduit includes the double acting valve located at the inlet of the member HT and the outlet of the member HT connects to the pump by a pipe which includes the thermostatic valve located at the outlet of the member HT of the heat exchanger. 
         [0015]    The third circuit includes the electrical energy storage device, a pump, and the member TBT of the heat exchanger. The inlet of the pump connects to the outlet of the heat transfer fluid of the electrical energy storage device, and the outlet of the pump connects to the inlet of the member TBT. The outlet of the member TBT connects to the first circuit through the intermediary of the thermostatic valve, and or to the electrical energy storage device. The inlet of the member TBT connects to the first circuit through the intermediary of the valve located at the inlet of the member TBT. 
         [0016]    The second circuit can include the member BT of the heat exchange device, a pump, an inverter, an electrical machine, and an automatic start and stop device of the combustion engine. 
         [0017]    Advantageously, the first and third circuits include a common degassing box. 
         [0018]    The electrical energy storage device includes at least one battery. 
         [0019]    According to another embodiment, each of the members TBT, HT and BT includes an inlet box for the heat transfer fluid, a radiator, and an outlet box for heat transfer fluid. 
         [0020]    The inlet boxes of members TBT and HT define a common passage which close with a valve so that a portion of the heat transfer fluid circulates from the TBT inlet box to the HT box. The TBT and HT outlet boxes define a common passage which close with a thermostatic valve so that a portion of the heat transfer fluid circulates from the HT outlet box to the TBT outlet box. 
         [0021]    When the flow of the heat transfer fluid in the first circuit for cooling of the combustion engine is less than a predetermined value, the valve opens the common passage of the inlet boxes to allow a portion of the heat transfer fluid of the TBT inlet box to flow to the HT inlet box. The valve closes the first circuit when the flow of heat transfer fluid in the cooling circuit of the combustion engine is zero. 
         [0022]    The thermostatic valve opens the common passage between the members HT and TBT of the exit boxes and closes the outlet of the HT exit box when the temperature of the heat transfer fluid at the outlet of the member HT is lower than a predetermined temperature. Conversely, the thermostatic valve closes the common passage between the members HT and TBT of the outlet boxes and opens the outlet of the HT outlet box when the temperature of the heat transfer fluid at the outlet of the HT outlet box is greater than the predetermined temperature, which equals the optimal operating temperature of the electrical energy storage device. 
         [0023]    The first circuit for cooling the combustion engine includes a thermostatic valve located at the outlet of the water outlet box, with which the circulation of the heat transfer fluid in the first circuit stops when the temperature of the heat transfer fluid in the water outlet box is lower than the optimal operating temperature of the combustion engine. 
         [0024]    The invention also relates to a radiator for circulation of the heat transfer fluid and installation in a hybrid vehicle. According to the invention, the radiator includes three distinct members separated from each other by a wall. Each of the members includes an inlet box having an inlet for heat transfer fluid, a heat exchanger, and an outlet box equipped with an outlet for heat transfer fluid. One of the walls separates the inlet boxes between two adjacent members to define a first passage. The wall separating the outlet boxes between the two adjacent members defines a second passage, whereby the first closing device moves between two positions. In a first position the inlet of an inlet box is open and the first passage is closed. In a second position the inlet of an inlet box is closed and the first passage is open. The second closing device moves between two positions. In a first position the outlet of an outlet box is open and the second passage is closed. In a second position the exit of the exit box is closed and the second passage is open. 
         [0025]    The first closing device includes a double acting valve which changes position when the pressure exercised on the valve is zero. The second closing device includes a thermostatic valve which can change position at 40°. 
         [0026]    The foregoing and other features, and advantages of the disclosure as well as embodiments thereof will become more apparent from the reading of the following description in connection with the accompanying drawings. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0027]    In the accompanying drawings which form part of the specification: 
           [0028]      FIG. 1  is a schematic of a prior art cooling device, 
           [0029]      FIG. 2  is a schematic is a first embodiment of a cooling device according to the present invention; 
           [0030]      FIG. 3  is a schematic of a second embodiment of a cooling device according to the present invention; 
           [0031]      FIG. 4  is a schematic of a radiator according to the present invention; and. 
           [0032]      FIG. 5  is a schematic of the radiator of  FIG. 4  with a water outlet box in an open position according to the present invention. 
       
    
    
       [0033]    Corresponding reference numerals indicate corresponding parts throughout the several figures of the drawings. 
       DETAILED DESCRIPTION 
       [0034]    The following detailed description illustrates the claimed invention by way of example and not by way of limitation. The description clearly enables one skilled in the art to make and use the disclosure, describes several embodiments, adaptations, variations, alternatives, and uses of the invention, including what is presently believed to be the best mode of carrying out the claimed invention. Additionally, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. 
         [0035]    The device shown in  FIG. 1  represents the most widely used configuration for cooling of the various elements of a hybrid vehicle. It includes a combustion engine  10 , a water outlet box  12 , an electrical machine  14  (such as the electrical motor(s) providing traction to the vehicle), a transmission  16 , and electrical energy storage device  18  (such as one or more batteries or one or more super capacitors). For clarity reasons, the electrical energy storage device is referred to in the specification by the term “battery”, with the understanding that this term covers all kinds of electrical energy storage device. 
         [0036]    The hybrid vehicle includes three different cooling circuits: a first circuit  20  dedicated to cooling the combustion engine  10 , (also referred to as a “HT circuit” for High Temperature and shown in  FIG. 1  and the following figures in solid line; a second circuit  22  for cooling of the electrical components, (also referred to as a “BT circuit” for Low Temperature and shown in double solid line), and a third circuit  24  for cooling of battery  18  (also referred to as a “TBT circuit” for Very Low Temperature and shown in dashed line). In general, the electrical components include the electrical machine  14 , an inverter  26 , and often an automatic start and stop system  28  (usually referred to as “Stop &amp; Start”). A heat transfer fluid, usually a mixture of water and glycol such as 50% water and 50% glycol, can flow in these three circuits in directions indicated by the arrows. 
         [0037]    In the first circuit  20  (HT circuit), the heat transfer fluid circulates in the combustion engine  10  and leaves the engine through the water outlet box  12  (remark: this is the normal designation of the outlet box, although it relates to the coolant outlet which is normally not pure water). Box  12  has two outlets: an outlet  30  which can be closed by a thermostatic valve  32  and an outlet  34 . Exiting through outlet  34 , the heat transfer fluid is aspirated by a pump  36 , such as an electric pump, and sent to an air heater  38  to heat the vehicle cabin. 
         [0038]    Before penetrating the air heater  38 , the heat transfer fluid can, if necessary, pass through a reheater  40 , such as an electrical or gasoline heater. Leaving the air heater  38 , the fluid flows towards a pump  42 , generally referred to as a “water pump”, from where it returns to the combustion engine. A degassing box  44  common to the first circuit  20  and the second circuit  22  evacuates the gas which could be present in the heat transfer fluid and fills the level of heat transfer fluid in the cooling circuits  20  and  22 . Exiting through the outlet  30  of the water outlet box  12 , the heat transfer fluid passes through a heat exchanger  46  (HT for High Temperature), such as a radiator installed in the front of the vehicle, and passes through the water pump  42  before returning to the combustion engine  10 . A bypass  43  allows for the return of the heat transfer fluid to the water outlet box  12  when the thermostatic valve  32  closes outlet  30 . 
         [0039]    The second circuit  22  (BT circuit) for cooling of the electrical components, includes a heat exchanger  48 , such as a radiator (also referred to as BT exchanger or BT radiator for Low Temperature). The heat transfer fluid circulates through the second circuit  22  with an electric pump  50 . The fluid then passes sequentially through the pump  50 , the inverter  26 , the electrical machine  14 , the automatic start and stop system  28  of the combustion engine and the BT radiator  48 . 
         [0040]    The third circuit  24  (TBT circuit) includes a heat exchanger or radiator  52  or TBT (TBT for Very Low Temperature). The heat transfer fluid is circulates with an electric pump  54  and passes sequentially through the TBT radiator  52  and battery  18 . In fact, the fluid does not pass through the battery  18  itself, but through the heat exchange device for cooling of the battery, such as a copper pipe in the form of a coil surrounding the battery. 
         [0041]    The temperature HT of the heat transfer fluid present in the first circuit  20  can vary from 70 to 110° C. The thermostatic valve  32  closes the outlet  30  and stops the circulation of the heat transfer fluid in the first HT circuit when the temperature of the fluid in the HT circuit is lower than the optimal operating temperature of the combustion engine, generally about 80° C. 
         [0042]    The temperature of the heat transfer fluid in the second BT circuit  22  is generally maintained about 60° C., or the optimal operating temperature of the electrical machine  14 . 
         [0043]    The temperature of the heat transfer fluid in the third TBT circuit  24  is generally maintained about 40° C., or the optimal operating temperature of the battery  18 . 
         [0044]    The differences in the optimal operating temperatures of the combustion engine, the electrical machine, and the battery are the reason for using three different circuits, and thus three radiators. This increases the fabrication cost of the vehicle and increases the space occupied under the hood. 
         [0045]      FIG. 2  illustrates a schematic of a first embodiment of the present invention where the use of a heat exchanger is shared between the combustion engine and the battery based on the operating conditions of the vehicle. In  FIG. 2 , the elements common with  FIG. 1  are indicated by the same reference numbers. There are three cooling circuits: the second circuit  22  (BT circuit) includes an identical radiator  48 , an electric pump  50 , an inverter  26 , an electrical machine  14  and a Stop &amp; Start system  28  or STT. 
         [0046]    The first circuit  60  (HT circuit) is identical to the first circuit  20  of  FIG. 1 , except that the first circuit  60  of  FIG. 2  includes a double acting valve  62  located upstream (in the direction of the heat transfer fluid flow) of radiator  46  (HT radiator), and a thermostatic valve  64  located downstream of the HT radiator. More specifically, valve  62  is located in a pipe  66  linking the outlet  30  of the water outlet box  12  to the HT radiator. In addition, a conduit  68  connects conduit  70 , thereby, connecting the pump  54  to radiator  52  (TBT radiator). Conduit  68  communicates with pipe  66  opposite valve  62  so that when valve  62  closes pipe  66 , the heat transfer fluid flows through the pipe  68  towards the HT radiator. Conversely, when valve  62  is open, the communication between pipe  66  and the HT radiator is open while the communication between pipe  68  and the HT radiator is closed. 
         [0047]    The thermostatic valve  64  is located downstream of the HT radiator in a pipe  72  linking outlet  74  of the HT radiator with the water pump  42 . The TBT circuit includes a conduit  76  linking pipe  72  with battery  18 , pipe  76  connects with pipe  72  at the location of the thermostatic valve  64  so that, when valve  64  closes pipe  72 , the heat transfer fluid exiting the HT radiator can flow in pipe  76  and, inversely, when valve  64  is not closing pipe  72 , the heat transfer fluid exiting the HT radiator cannot flow in pipe  76 . 
         [0048]    The third circuit  78 , dedicated to cooling of battery  18 , includes TBT radiator  52 , pipe  80  (linking the outlet  82  of radiator  52  with pipe  68 ), pipe  76 , battery  18  (generally the electrical energy storage device), and the pump  54  connected to the battery  18  through the pipe  84  and linked to the inlet  86  of the TBT radiator  52  through the intermediary of the pipe  70 . 
         [0049]    Advantageously, radiators  52 ,  46  and  48  can be formed by a single heat exchanger  88  separated in three distinct members to form the three radiators  52  (TBT),  46  (HT) and  48  (BT). 
         [0050]    As before, the HT circuit  46  or first circuit is shown in continuous solid line, the BT circuit  48  or second circuit is shown in double line, and the TBT circuit  52  or third circuit in dashed line. 
         [0051]    The double acting valve  62  establishes the communication between the first circuit  60  and the third circuit  78  when the flow of heat transfer fluid in pipe  72  is very low, or practically zero. This situation occurs when the thermostatic valve  32  closes the outlet of the water outlet box  12 , which occurs when the temperature of the heat transfer fluid in the water outlet box  12  is below the optimal operating temperature of the combustion engine. The optimal operating temperature can be for example between  80  and  110 ° C. In this case, outlet  30  is open when the temperature of the heat transfer fluid is equal to or higher than for instance 80° C. and the output  30  is closed when the temperature of the heat transfer fluid is lower than 80° C. 
         [0052]    When valve  32  closes outlet  30  of the water outlet box, the valve  62  opens the communication between pipe  68  and the HT radiator, thereby, placing the third circuit  78  (TBT) in communication with the first circuit  60  (HT). The double acting thermostatic valve  64  is calibrated to open pipe  72  at a predetermined temperature, which corresponds with the optimal operating temperature of battery  18 . For example, this temperature can be about 40° C. 
         [0053]    A device according to the invention functions in different ways according to the conditions of vehicle use. For example: 
         [0054]    First Use Conditions:
       Combustion engine used little or stopped,   Reheater  49  used little or stopped,   Electrical machine  14  stopped or running,   Charging of the battery starting from the electric grid.       
 
         [0059]    When the temperature of the heat transfer fluid in the HT circuit  60  is less than 80° C., the thermostatic valve  32  is closed. The heat transfer fluid coming from the combustion engine  10  is directly sent to the reheater  40  and the air heater  38  to heat the vehicle cabin. When the heat transfer fluid is not flowing through the HT radiator, the flow in pipe  66  is zero. Therefore, valve  62  is in a closed position with no pressure applied on it. The heat transfer fluid of the third circuit  78  (TBT) then passes through the HT radiator in addition to the TBT radiator. In this way, the cooling of battery  18  improves by increasing the exchange surface area of the heat transfer fluid in the heat exchanger  88 . Since the temperature in the third circuit TBT does not exceed 40° C., the thermostatic valve  64  is in closed position and the heat transfer fluid exiting the HT radiator is returned to battery  18 . Furthermore, the thermostatic valve  64  prevents any risk of sending heat transfer fluid with a temperature higher than 40° C. to battery  18 , which would degrade its performance and/or life. The flow in the third TBT circuit  78  is provided by the electric pump  54 , so that the cooling of the battery is ensured when the combustion engine is stopped. 
         [0060]    These operating conditions correspond to the times that the battery requires the most cooling. The surface area of the heat exchanger becomes more important during this period. 
         [0061]    Second Use Conditions:
       Combustion engine  10  runs,   Reheater  40  functioning or stopped,   Electrical machine  14  stopped or little used,   Charging of the battery  18  with the power of the combustion engine.       
 
         [0066]    When the combustion engine requires cooling, for temperatures of the heat transfer fluid in the first HT circuit  46  higher than 80° C., the thermostatic valve  32  opens. Under the pressure of the heat transfer fluid, valve  62  also opens and closes pipe  76 . The heat transfer fluid coming from the combustion engine  10  cools in the HT radiator. Since the temperature at the outlet  74  of the HT radiator is greater than 40° C., the thermostatic valve  32  also opens so that the fluid is sent in direction of the combustion engine through pipe  72 . The battery  18  then cools only by the TBT radiator, whereby valve  62  and thermostatic valve  64  closes pipes  68  and  76  to link the third TBT circuit with the HT radiator. 
         [0067]    The second operating conditions correspond to times when the battery  18  is charging starting from the power of the combustion engine  10 . Therefore, only minimum cooling of the battery  18  must be provided. Since the cooling requirement is less significant than in the first conditions, the heat exchange surface of the TBT radiator is sufficient. 
         [0068]      FIG. 3  illustrates a schematic of a second embodiment of the invention. This embodiment generally includes the same elements as those of the embodiment mode shown in  FIG. 2 , and the common elements are indicated by the same reference numbers. The differences between the two embodiments relate to the heat exchanger, framed in an oval  88 , the valve  62 , and the thermostatic valve  64 . Heat exchanger  88  includes a single radiator divided in three members TBT, HT and BT. In the second embodiment, the valve  62  and the valve  64  are integrated in the HT radiator. This arrangement simplifies the HT and TBT circuits, since the communication between the HT and TBT circuits is established in the heat exchanger  88 , and more specifically between the HT and TBT members of the heat exchanger, due to the use of a new type of radiator as shown in  FIGS. 4 and 5 . In  FIG. 3 , outlet  74  of the HT radiator is directly connected to water pump  42 , and the communication conduit  88  and member of conduit  76  have been eliminated. 
         [0069]    The heat exchanger  88  is represented schematically in  FIG. 4 , which shows a situation in which the temperature of the heat transfer fluid in the HT circuit  60  is lower than the optimal operating temperature of the combustion engine, for example, lower than 80° C.). Exchanger  88  is a “complex” radiator with exchange of coolant between the TBT and HT members. This radiator includes three members: a TBT member (Very Low Temperature)  90 , a HT member (High Temperature)  92 , and a BT member (Low Temperature)  94 . The TBT and HT members are separated by a wall  96  and the HT and BT members are separated by a wall  98 . 
         [0070]    Each of the members includes a heat transfer fluid inlet box ( 100  for the TBT member,  102  for the HT member and  104  for the BT member), a heat exchanger member ( 106  for the TBT member,  108  for the HT member and  110  for the BT member) and an outlet box ( 112  for the TBT member,  114  for the HT member and  116  for the BT member). The heat transfer fluid circulates in the directions indicated by the arrows in dashed lines for the TBT member  106 , in solid line for the HT member  108 , and double lines for the BT member  110 . 
         [0071]    Each of the inlet boxes  100 ,  102 , and  104  is equipped with an inlet for the heat transfer fluid respectively  118 ,  120  and  122 . Each of the outlet boxes  112 ,  114  and  116  includes a fluid outlet respectively  124 ,  126  and  128 . Wall  96  separating the TBT and HT members  106  and  108  includes a first communication passage  130  between the inlet boxes  100  and  102  and a second communication passage  132  between outlet boxes  112  and  114 . Passage  130  includes a first closing device  134  which can assume two positions, one position in which the inlet  120  of the inlet box  102  is open and the first passage  130  is closed, and a second position in which inlet  120  of the inlet box  102  is closed and the first passage  130  is open. Passage  132  includes a second closing device  136  which can assume two positions, one position in which the outlet  126  of the outlet box  114  is open and the second passage  132  is closed, and a second position in which the outlet  126  is closed the second passage  132  is open. 
         [0072]    The closing device  134  includes a double acting valve equivalent to valve  62  of the embodiment of  FIG. 2 . This valve  62  closes inlet  120  and opening passage  130  when the flow in pipe  72  is very low, even zero, and therefore when the temperature of the heat transfer fluid is lower than 80° C. for example (temperature for which the thermostatic valve  32  closes the outlet  30  of the water outlet box). 
         [0073]    The closing device  136  includes a thermostatic valve identical to the thermostatic valve  64  of the embodiment mode of  FIG. 2 . This valve closes the outlet  126  and opens passage  132  when the temperature of the heat transfer fluid in the outlet box  114  is lower than the optimal operating temperature of the battery  18 , for example  40  ° C. 
         [0074]    The conditions for circulation of the heat transfer fluid from the TBT circuit to the HT radiator are the following: when the thermostatic valve  32  of the water outlet box closes outlet  30 , the flow in the HT radiator is zero; valve  134  closes inlet  120  of the HT radiator and the passage  130  is open; the inlet boxes  100  and  102  communicate and some of the heat transfer fluid of the TBT circuit can then pass through the HT circuit. The fluid contained in the HT radiator cools down. As soon as the temperature of this fluid is lower than 40° C., the thermostatic valve  136  opens passage  132  and closes outlet  126  of the HT radiator. The heat transfer fluid of the TBT circuit can then circulate in the HT circuit, more specifically in the radiator  108  of the HT circuit. 
         [0075]      FIG. 5  shows the radiator of  FIG. 4 , when the thermostatic valve  32  of the water outlet box is in open position, in other words, when the outlet  30  is open. This corresponds with a coolant temperature higher than or equal to the optimal operating temperature of the combustion engine, for example 80° C. There is no circulation of heat transfer fluid from the TBT circuit to the HT circuit. Indeed, valve  134  closes passage  130  and opens inlet  120  of the HT radiator  108 . The thermostatic valve  136  (open until about 40° C.) is open. In other words, it opens outlet  126  of the HT radiator and closes passage  132 . Therefore, there is no communication between the TBT and HT circuits. In this case, the result is that the HT radiator is dedicated to the cooling of the combustion engine. 
         [0076]    The advantages provided by the present invention are for example and in non-limiting manner: 
         [0077]    Intelligent thermal management of the cooling circuit, 
         [0078]    Splitting the radiator for cooling different elements operating in much different temperature ranges, 
         [0079]    The absence of a supplementary heat exchanger, either in front of the vehicle or elsewhere in the vehicle, 
         [0080]    The absence of the additional motor-ventilator group and the use of the main motor-ventilator group in front, 
         [0081]    Easier installation of the cooling circuit in the vehicle due to less space occupied by the radiator of the invention compared to the three radiators of prior art, 
         [0082]    The electrical consumption of the cooling circuit is low compared to the electrical consumption of a cooling circuit using air or coolant. 
         [0083]    Changes can be made in the above constructions without departing from the scope of the disclosure, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.