Patent Publication Number: US-11660935-B2

Title: Vehicle cabin and high voltage battery thermal management system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. application Ser. No. 15/927,592, filed Mar. 21, 2018, now U.S. Pat. No. 10,814,700, issued Oct. 27, 2020, the disclosure of which is hereby incorporated in its entirety by reference herein. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to thermal management systems to assist in managing thermal conditions for cabins and high voltage batteries of vehicles. 
     BACKGROUND 
     Vehicle thermal management systems may include a first thermal loop for managing thermal conditions of a high voltage battery and a second thermal loop for managing thermal conditions of a vehicle cabin. Electrified vehicles often include a powertrain requiring an air conditioning (A/C) system to provide cooling functions to the high voltage battery. The powertrain may still engage the A/C system to cool the high voltage battery in a scenario in which a passenger requests climate control off or A/C system off. In this scenario, engagement of the A/C system leads to undesired cooling of the vehicle cabin contrary to the requested climate control off or A/C system off made by the passenger. 
     SUMMARY 
     A vehicle thermal management system includes an electric powertrain, a single thermal loop, and a controller. The electric powertrain includes a high voltage battery. The single thermal loop is for managing thermal conditions of the high voltage battery and a vehicle cabin and includes a climate control system, a blower, and a front evaporator in fluid communication with the vehicle cabin. The controller is programmed to, responsive to detection of a climate control system off request, output a command to direct the blower to push air through a heater core to the vehicle cabin at a predetermined temperature such that a temperature within the vehicle cabin is maintained at a predetermined temperature and refrigerant continues to flow through the front evaporator. The system may include a vehicle cabin temperature sensor and an ambient temperature sensor, each in electrical communication with the controller. The predetermined temperature may be based on temperature sensor signals received by the controller from one of the vehicle cabin temperature sensor or the ambient temperature sensor. The system may include a chiller. The controller may be further programmed to control coolant flow through the chiller to maintain a temperature of the high voltage battery within a predetermined temperature range and to reduce an impact on vehicle cabin temperature. The controller may be further programmed to direct the blower to output the air to the vehicle cabin and maintain coolant flow through a chiller in accordance with noise, vibration, and harshness standards. The system may include a rear evaporator. The single thermal loop may include only one evaporator shut off valve in fluid communication with one of the front evaporator or the rear evaporator. The system may include a chiller arranged with the front evaporator such that the coolant flow continues to maintain a predetermined temperature of the high voltage battery and refrigerant flows through the front evaporator while the blower outputs air to the vehicle cabin at a temperature based on a vehicle cabin temperature or an ambient temperature. The controller may be further programmed set the blower at a predetermined low speed. The controller may be further programmed to output the command to the blower to push air through the heater core based on a detected compressor speed being above a predetermined threshold. The controller may be further programmed to output the command to the blower to push air through the heater core based on a detected front evaporator temperature being below a predetermined threshold. 
     A vehicle thermal management system includes a blower, an evaporator a chiller, and a controller. The blower and evaporator are in fluid communication with a vehicle cabin. The chiller is for facilitating fluid communication between the evaporator and a high voltage battery. The controller is programmed to, responsive to detection of a front control head of an air conditioning system in an off state, output a control signal to the blower to move air across a heat source and to the vehicle cabin at a predetermined temperature while maintaining refrigerant flow through the evaporator and maintaining coolant flow through the chiller to maintain a high voltage battery temperature within a predetermined battery temperature range. The controller may be further programmed to adjust the predetermined temperature of the air to the vehicle cabin based on detected changes in vehicle cabin temperature. The controller may be further programmed to output the control signal to the blower based on a detected climate control system off request and a high voltage battery temperature being above a predefined threshold. Refrigerant flow to the evaporator may not be controlled by a shut-off valve. The system may further include a compressor in fluid communication with a climate control system and a compressor speed sensor. The controller may be further programmed to output the control signal to the blower based on a detected compressor speed. The controller may be further programmed to activate a blend door control to move the air across the heat source based on detection of a thermal management system front control head in an off status. 
     A vehicle thermal management control strategy outputs a command, by a controller, for a blower to direct airflow across a heat source en route to a vehicle cabin to maintain a temperature of the vehicle cabin at or above a detected ambient temperature outside the vehicle cabin in response to detection of an air-conditioning system off request. The controller may be programmed to responsive to the detection of the air-conditioning system off request, output a command to a chiller to maintain coolant flow and to output a command to an evaporator to maintain refrigerant flow. The controller may be further programmed to update a temperature of the airflow based on changed and detected vehicle cabin temperatures. The controller may be further programmed to control a flow of refrigerant to an evaporator without a use of a shut-off valve. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram illustrating an example of a portion of a prior art architecture for a vehicle thermal management system including two thermal loops. 
         FIG.  2    is a schematic diagram illustrating an example of a portion of an architecture for a vehicle thermal management system including a front evaporator shut-off valve. 
         FIG.  3 A  is a schematic diagram illustrating an example of a portion of an architecture for a vehicle thermal management system without a front evaporator shut-off valve and including a control unit. 
         FIG.  3 B  is a diagram illustrating an example of a portion of a heating, ventilation, and air-conditioning system for a vehicle. 
         FIG.  4    is a flow chart illustrating an example of a portion of a control strategy for a vehicle thermal management system. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments may take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present disclosure. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures may be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be used in particular applications or implementations. 
       FIG.  1    is a schematic diagram illustrating a portion of an architecture of a vehicle thermal management system, referred to generally as a thermal management system  10  herein. The thermal management system  10  includes a first thermal loop  14  and a second thermal loop  16 . As used herein, a thermal loop is a vehicle system loop including vehicle components and a conduit assembly to transfer fluid for managing thermal conditions of the vehicle components and portions of the vehicle adjacent thereto. The first thermal loop  14  assists in controlling thermal conditions of a vehicle cabin. The first thermal loop includes a front cabin evaporator  20 , a rear cabin evaporator  22 , a compressor  24 , and a condenser  26 . 
     The second thermal loop  16  assists in controlling thermal conditions of a high voltage battery. The second thermal loop  16  includes a high voltage battery  30 , a pump  32 , a battery radiator  34 , a three-way valve  36 , a refrigerant to coolant heat exchanger  38 , a compressor  40 , and a condenser  42 . In this example, the first thermal loop  14  and the second thermal loop  16  are not in fluid communication with one another and operate separately. 
       FIG.  2    is a schematic diagram illustrating another portion of an architecture of a vehicle thermal management system, referred to generally as a thermal management system  50  herein. The thermal management system  50  includes a front evaporator  52  and a rear evaporator  54 . A rear evaporator shut-off valve (RESOV)  55  may control a flow of refrigerant to the rear evaporator  54 . A front evaporator shut-off valve (FESOV)  56  may control flow of refrigerant to the front evaporator  52 . The thermal management system  50  may further include an internal heat exchanger  58 , a condenser  60 , a pressure sensor  62 , and a compressor  64 . A chiller  70  may assist in transferring heat between portions of the thermal management system  50  to assist in maintaining thermal conditions of a high voltage battery. A chiller shut-off valve (CHSOV)  71  may control a flow of refrigerant to the chiller  70 . 
     Coolant may travel from the chiller  70  through a first three-way valve  72  and a second three-way valve  74  en route to a high voltage battery  76 . A pump  78  may assist in controlling movement of the coolant to assist in managing thermal conditions of the high voltage battery  76 . The first three-way valve  72  may operate to direct the coolant from the chiller  70  through a bypass line to avoid distributing the coolant to the high voltage battery  76 . The second three-way valve  74  may operate to direct the coolant to a radiator  80  instead of to the high voltage battery  76 . In comparison to the thermal management system  10 , the thermal management system  50  includes only one thermal loop to manage thermal conditions of the vehicle cabin and the high voltage battery  76 . 
       FIG.  3 A  is a schematic diagram illustrating an example of a portion of an architecture of a vehicle thermal management system, referred to generally as a thermal management system  100 . In contrast to the thermal management system  10 , the thermal management system  100  includes only one thermal loop to manage thermal conditions of a vehicle cabin and a high voltage battery. Inclusion of only one thermal loop instead of two thermal loops provides an architecture with fewer components and reduced assembly time thus presenting cost advantages in comparison to the thermal management system  10  of  FIG.  1   . 
     The thermal management system  100  includes components to assist in managing thermal conditions of the vehicle cabin and the high voltage battery with one less shut-off valve in comparison to the thermal management system  50 . For example, the thermal management system  100  may include a front heating, ventilating, and air conditioning (HVAC) system  104  and a rear HVAC system  106 . Each of the front HVAC system  104  and the rear HVAC system  106  may be in fluid communication with a vehicle cabin (not shown in  FIG.  3 A ) to assist in managing thermal comfort of passengers within the vehicle cabin. Each of the front HVAC system  104  and the rear HVAC system  106  may include an evaporator, a blower, a heat source, and a conduit system. 
       FIG.  3 B  illustrates an example of a portion of a vehicle HVAC system, referred to as an HVAC system  170  herein. Each of the front HVAC system  104  and the rear HVAC system  106  may include components similar to the HVAC system  170 . The HVAC system  170  includes an ambient inlet to selectively receive air from outside the vehicle as represented by arrow  172  and a cabin inlet to receive air from inside the vehicle as represented by arrow  174 . An air filter  175  may operate to filter air received from outside the vehicle. A recirculation flap  176  may operate to selectively permit air to flow from outside or inside the vehicle to the HVAC system  170 . In  FIG.  3 B , the recirculation flap  176  is shown in a position to permit air from outside the vehicle to flow into the HVAC system  170 . 
     A blower  177  may operate to move the air throughout the HVAC system  170 . For example, the blower  177  may direct air to flow as represented by arrow  178  to an evaporator core  179 . The evaporator core  179  may operate to selectively cool the air and remove moisture. An evaporator drain  180  may operate to remove undesired material from the evaporator core  179 , such as the moisture. A blend door  182  may selectively direct the air flow to pass through a heat source  184 , such as a heater core, or to route the air flow around the heat source  184 . 
     For example, the blend door  182  may operate to direct the air flow through the heat source  184  in response to a passenger request including heat, such as an activate heat request or an activate defog request. Alternatively, if a passenger requests cool air, the blend door  182  may be positioned to prevent the air flow from passing through the heat source  184  and the evaporator core  179  may be activated to cool the air flow. 
     A first mode door  186  and a second mode door  188  may also operate to direct the air flow based on passenger requests. For example, the first mode door  186  and the second mode door  188  may be positioned such that air may travel to floor vents as represented by arrow  190 , to main upper vents as represented by arrow  192 , or to defrost vents as represented by arrow  194 . 
     Referring back to  FIG.  3 A , a first thermal expansion valve  107  may operate to adjust a flow rate of refrigerant passing therethrough based on thermal conditions of the refrigerant. A second thermal expansion valve  109  may operate to adjust a flow rate of refrigerant passing therethrough based on thermal conditions of the refrigerant. The second thermal expansion valve  109  may include a shut-off valve to selectively prevent refrigerant from flowing to the second evaporator of the rear HVAC system  106 . 
     It is contemplated that the thermal management system  100  may operate in an example in which a first thermal expansion valve includes shut-off valve characteristics and a second thermal expansion valve does not include shut-off valve characteristics. 
     A first blower may be in fluid communication with a first evaporator of the front HVAC system  104  similar to the configuration described in relation to the HVAC system  170  above. A second blower may be in fluid communication with a second evaporator of the rear HVAC system  106 . In contrast to the thermal management system  50  of  FIG.  2   , the thermal management system  100  does not include a FESOV to control refrigerant flow to the first evaporator of the front HVAC system  104 . Exclusion of the front shut-off valve provides a cost savings and provides noise, vibration, and harshness (NVH) benefits and improves the passenger&#39;s ride experience since operation of the front shut-off valve may be noisy. For example, operation of the system with a front shut-off valve generates undesired noise when refrigerant flow and/or pressure is adjusted when flowing through the front shut-off valve. 
     A control unit  112 , also referred to as a controller herein, may be in electrical communication with the front HVAC system  104  and the rear HVAC system  106  to selectively direct operation thereof. One or more blend doors may be included in the conduit system to selectively move air at various temperatures to the vehicle cabin based on signals received from the control unit  112 . For example, the control unit  112  may include programming to direct operation responsive to detected operating conditions of the thermal management system  100  as further described herein. 
     An internal heat exchanger  120  may operate to assist in controlling thermal conditions of refrigerant received from a cabin climate control system  122  and a compressor  124 . The cabin climate control system  122  may be, for example, a cooling module. In an embodiment in which the cabin climate control system  122  is a cooling module, the cabin climate control system  122  may include a condenser  128 , a radiator  130 , and an air conditioning (A/C) fan  132 . The compressor  124  and the A/C fan  132  may be in electrical communication with the control unit  112  to receive operating instructions therefrom. The compressor  124  may include a speed sensor  125  in electrical communication with the control unit  112  to provide signals indicating compressor  124  operating speeds. The control unit  112  may direct operation of refrigerant and coolant flow within the thermal management system  100  based on the received signals from the speed sensor  125 . 
     A chiller  140  may operate to exchange heat between refrigerant of a portion of the thermal management system  100  relating to the vehicle cabin and coolant of a portion of the thermal management system  100  relating to a high voltage battery by facilitating fluid communication therebetween. The chiller  140  assists in providing a thermal management system architecture with a single thermal loop to manage the thermal conditions of both the vehicle cabin and the high voltage battery. Coolant may flow from the chiller  140  to a high voltage battery  144  via a first three-way valve  146  and a second three-way valve  148 . A pump  150  may operate to control movement of the coolant. 
     The first three-way valve  146  may operate to make use of a by-pass line such that the coolant flowing from the chiller  140  will selectively not enter the high voltage battery  144 . The second three-way valve  148  may operate to direct coolant to the high voltage battery  144  and/or to the radiator  130 . For example, operating conditions of the thermal management system  100  may be such that coolant may be directed to flow through the radiator  130  to assist in managing thermal conditions of the high voltage battery  144 . 
     An internal temperature sensor  160  and an external temperature sensor  162  may each be in electrical communication with the control unit  112  to send signals indicating detected temperature conditions. The internal temperature sensor  160  may monitor thermal conditions of, for example, the vehicle cabin. The external temperature sensor  162  may monitor thermal conditions of, for example, ambient conditions outside the vehicle cabin. The control unit  112  may include programming to direct operation of the components of the thermal management system  100  to manage thermal conditions of the vehicle cabin and the high voltage battery  144  without requiring multiple thermal loops and additional components which may have negative impacts on NVH standards. 
     For example, the programming may direct activation of the first blower and/or the second blower to move air through a respective evaporator of a respective HVAC system to the vehicle cabin. The first blower and/or the second blower may be activated based on detected conditions of the components of the thermal management system  100  or a detected temperature within the vehicle cabin or a detected temperature of the ambient conditions outside the vehicle cabin. 
     In one example, when the chiller  140  is in operation to manage thermal conditions of the high voltage battery  144 , refrigerant will be flowing through the evaporators and a passenger may have requested the climate control system  122  to be off. For example, the passenger may turn the A/C system off. In previous systems, the A/C system may continue to output cool air regardless of the passenger request so that the high voltage battery continues to be cooled. The refrigerant flow through the evaporators may cause undesired cooling temperature conditions to passengers within the vehicle cabin. To avoid the undesired cooling temperatures within the vehicle cabin, the control unit  112  may activate the first blower and/or the second blower to move air at a predetermined temperature to the vehicle cabin. For example, blend doors of one of the HVAC systems may be positioned to facilitate a desired air flow in combination with selected operation of a respective heater core and a respective evaporator. The predetermined temperature may be based on temperatures detected by the internal temperature sensor  160  and/or the external temperature sensor  162 . In one example, the air may be moved through the respective HVAC system at a temperature equal to or greater than the detected ambient temperature to maintain a comfortable temperature within the vehicle cabin while continuing to cool the high voltage battery  144  and maintain refrigerant flow through the evaporators. In another example, the air may be moved at a temperature equal to or greater than the detected vehicle cabin temperature to maintain comfortable temperature within the vehicle cabin while continuing to cool the high voltage battery  144  and maintain refrigerant flow through the evaporators. 
     In the event the detected ambient temperature is within a predetermined range equating to an uncomfortable passenger temperature, the control unit  112  may direct operation of the HVAC systems to move air to the vehicle cabin based on temperature conditions detected by the internal temperature sensor  160 . 
       FIG.  4    is a flow chart illustrating an example of a control strategy for operation of a vehicle thermal management system, referred to as a control strategy  200  herein. The control strategy  200  may be used to direct operation of, for example, components of the thermal management system  100  described above. In operation  204 , a controller may detect whether a front control head of a thermal management system is in an on or off position. The front control head may be, for example, a user interface of a climate control system for a passenger to input climate control commands. 
     In the event the front control head is off, the controller may detect an operating status of a compressor of the thermal management system in operation  206 . Detection of the operating status of the compressor may be based on compressor revolutions per minute (RPM) detected by a sensor of the compressor. For example, if an RPM of the compressor is detected as reflecting a moderate or high operation state within a speed range in which a potential exists for liquid to return to the compressor, the control strategy  200  may be activated. In one example, such a compressor speed may be greater than 2500 RPM. 
     Alternatively, evaporator operating conditions may be examined to identify whether to advance to operation  208  or revert back to operation  204 . For example, evaporator operating conditions may be examined to identify whether a potential for a freeze condition exists. In one example, if an evaporator temperature is less than or equal to 2° C. plus a hysteresis, such as 4.5° C., the controller may direct advancement to operation  208 . 
     In the event the controller detects that the compressor is in an on state in operation  206 , the controller may direct activation of components of the thermal management system to maintain desired thermal conditions of the vehicle cabin while appropriately managing thermal conditions of a high voltage battery. For example, the controller may direct a blower to push air through an evaporator and/or a heater core in fluid communication with a vehicle cabin in operation  208  to obtain a selected temperature. The selected temperature may represent a temperature or range selected to reflect desired vehicle cabin thermal conditions for passengers. The selected temperature may be predetermined or may be selected based on a detected vehicle cabin temperature or a detected ambient temperature outside the vehicle. 
     The controller may activate other components of the thermal management system according to predefined operating conditions in operation  208 . A speed of the blower may be set to a low speed to further minimize impact to vehicle cabin passengers. A low speed as used herein may be a predetermined value, a calibrated value, or a configured value. In one example, a low speed may be approximately equal to 25% of a max speed. In one example, three volts may be supplied to the blower to operate at a low speed. In another example, a front air distributor may be set to a floor mode to minimize pushed air felt by the vehicle cabin passengers. In another example, a front air inlet door may be set to an outside air position. In another example, a temperature of the pushed air may be selected based on detected vehicle cabin temperatures plus an offset. In yet another example, a temperature of the pushed air may be sequentially varied based on changes to vehicle cabin temperature over a time-period. 
     In the event the controller detects that the front control head is in an on state in operation  204 , the controller may detect whether an A/C request is designated as off in operation  212 . In the event the A/C request is designated as on, the controller may return to operation  204 . In the event the A/C request is designated as off, the controller may proceed to operation  214 . 
     In operation  214 , the controller may direct operation of the thermal management system to address a scenario in which a passenger does not want to activate the A/C system but A/C system operation is needed to assist in managing thermal conditions of the high voltage battery. For example, an automatic blend door control may direct a target air discharge temperature to be no lower than a predetermined temperature range based on a detected ambient temperature plus an offset. In this example, the A/C system may be run without negatively impacting passenger comfort. 
     The words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments may be combined to form further embodiments of the invention that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics may be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes may include, but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, embodiments described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and may be desirable for particular applications.