Vehicles and vehicle cooling systems

Abstract

A vehicle includes a first cooling circuit, a second cooling circuit, and a controller. The first cooling circuit includes a compressor and a cooler. The second cooling circuit includes a valve and an evaporator. The second cooling circuit extends from an input side to an output side of the cooler on the first circuit. The controller is programmed to close the valve in response to operation of the cooler but not the evaporator and intermittently pulse open the valve whenever a discharge pressure of the compressor exceeds a first threshold.

Description

Technical Field

[0001] The present disclosure relates to a vehicle and a cooling system for a vehicle. Background Art

[0002] Vehicles may include a cooling or air conditioning system configured to cool spaces within the vehicle or specific components of the vehicle. Summary of the invention

[0003] A vehicle includes a first cooling circuit, a second cooling circuit, and a controller. The first cooling circuit includes a compressor and a cooler. The second cooling circuit includes a valve and an evaporator. The second cooling circuit extends from an input side to an output side of the cooler on the first circuit. The controller is programmed to close the valve in response to operation of the cooler but not the evaporator and intermittently pulse open the valve whenever a discharge pressure of the compressor exceeds a first threshold.

[0004] A vehicle cooling system includes a first refrigerant circuit, a second refrigerant circuit, and a controller. The first refrigerant circuit includes a first heat exchanger. The second refrigerant circuit includes a valve and a second heat exchanger. The second refrigerant circuit extends from a high pressure side of the first circuit to a low pressure side, the high pressure side and the low pressure side being on opposite sides of the first heat exchanger. The controller is programmed to close and intermittently pulse open the valve in response to operation of the first heat exchanger but not the second heat exchanger.

[0005] A vehicle includes a first refrigerant circuit, a second refrigerant circuit, and a controller. The first refrigerant circuit includes a cooler. The second refrigerant circuit includes an evaporator. The second refrigerant circuit extends from an input side to an output side of the cooler on the first circuit. The valve is disposed within the second circuit between the evaporator and the input side of the cooler. The controller is programmed to close and intermittently pulse open the valve in response to operation of the cooler but not the evaporator. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a schematic diagram of the vehicle; and

[0007] Figure 2 is a schematic diagram of a vehicle cooling system. DETAILED DESCRIPTION

[0008] Embodiments of the present disclosure are described herein. However, it should be understood that the disclosed embodiments are merely examples and that other embodiments may take various forms and alternative forms. The drawings are not necessarily drawn to scale; some features may be magnified or minimized to show the details of a particular component. Therefore, the specific structural details and functional details disclosed herein should not be interpreted as restrictive, but only as a representative basis for teaching those skilled in the art to adopt the embodiments in various ways. As will be understood by those of ordinary skill in the art, the various features shown and described with reference to any one of the accompanying drawings may be combined with the features shown in one or more other drawings to produce embodiments that are not explicitly shown or described. The combination of the features shown provides representative embodiments for typical applications. However, various combinations and modifications of features consistent with the teachings of the present disclosure may be desired for specific applications or implementations.

[0009] refer to Figure 1 , a vehicle 10 having a cabin 12, a battery 14, a cooling system 16, and a controller 18 is shown. The cooling system 16 is arranged to absorb heat from the air introduced into the cabin 12 and the battery 14. The cooling system 16 is also configured to transfer the absorbed heat to a heat exchanger (i.e., a condenser), which then discharges the heat to the surrounding environment or ambient air. The controller 18 is used to coordinate the cooling of the cabin air with the cooling of the battery 14. The battery 14 can be a traction battery configured to power an electric motor to propel the vehicle 10. The vehicle 10 can be any type of vehicle, including a non-hybrid vehicle (e.g., a vehicle propelled by an internal combustion engine), an electric vehicle (e.g., a battery-operated electric vehicle), or a hybrid vehicle. Hybrid configurations can include, but are not limited to, micro-hybrid vehicles, series hybrid vehicles, parallel hybrid vehicles, series-parallel hybrid vehicles, plug-in hybrid electric vehicles (PHEVs), fuel cell hybrid vehicles, or any other vehicle configuration known to those of ordinary skill in the art.

[0010] Although shown as one controller, the controller 18 may be part of a larger control system and may be controlled by various other controllers throughout the vehicle 10, such as a vehicle system controller (VSC). It should therefore be understood that the controller 18 and one or more other controllers may be collectively referred to as a "controller" that controls various actuators in response to signals from various sensors to control the functionality of the vehicle 10 or a vehicle subsystem. The controller 18 may include a microprocessor or central processing unit (CPU) that communicates with various types of computer-readable storage devices or media. The computer-readable storage devices or media may include, for example, volatile and non-volatile memory in a read-only memory (ROM), a random access memory (RAM), and a keep-alive memory (KAM). KAM is a persistent or non-volatile memory that can be used to store various operating variables when the CPU is powered off. The computer readable storage device or medium may be implemented using any of a number of known memory devices, such as a PROM (programmable read-only memory), an EPROM (electrical PROM), an EEPROM (electrically erasable PROM), flash memory, or any other electrical, magnetic, optical, or combination memory device capable of storing data, some of which represent executable instructions used by the controller 18 to control the vehicle 10 or a vehicle subsystem.

[0011] The control logic or functions performed by the controller 18 may include control strategies implemented using one or more processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, etc. Therefore, various steps or functions of the control logic or functions may be executed in a specific order, in parallel, or omitted in some cases. Those of ordinary skill in the art will recognize that one or more of the steps or functions may be repeatedly executed depending on the specific processing strategy used. Similarly, the processing order is not necessary to achieve the features and advantages described herein. The control logic may be implemented primarily in software executed by a microprocessor-based vehicle or vehicle subsystem controller (such as the controller 18). Of course, depending on the specific application, the control logic may be implemented in software, hardware, or a combination of software and hardware with one or more controllers. When implemented in software, the control logic may be provided in one or more computer-readable storage devices or media, which store data representing codes or instructions executed by a computer to control a vehicle or its subsystems. The computer-readable storage device or medium may include one or more of many known physical devices that utilize electrical, magnetic, and / or optical storage to store executable instructions and associated calibration information, operating variables, and the like.

[0012] The controller 18 may be configured to receive various states or conditions of various components of the vehicle 10 via electrical signals. The electrical signals may be delivered to the controller 18 from the various components via input channels. Additionally, the electrical signals received from the various components may indicate a request or command to change or alter the state of one or more of the corresponding components of the vehicle 10. The controller 18 includes output channels configured to deliver requests or commands (via electrical signals) to the various vehicle components. The controller 18 includes control logic and / or algorithms configured to generate requests or commands delivered via output channels based on requests, commands, conditions, or states of the various vehicle components.

[0013] refer to Figure 2 , a vehicle cooling system 16 is shown. The cooling system 16 includes a first cooling (or refrigerant) circuit 20. The first cooling circuit 20 includes a compressor 22, a condenser 24, a receiver / dryer 26, a shutoff valve (not shown), a thermal expansion valve (or optionally an electric expansion valve) 28, and a cooler 30 (which may be referred to as a first heat exchanger). The shutoff valve may be located between the receiver / dryer 26 and the thermal expansion valve 28 on the input side of the thermal expansion valve 28. The shutoff valve may be configured to block the flow of coolant or refrigerant within the first cooling circuit 20. More specifically, the shutoff valve in the first cooling circuit 20 may be incorporated into and integrated with the thermal expansion valve 28. The coolant or refrigerant in the first cooling circuit 20 flows from the compressor 22 to the condenser 24, from the condenser 24 to the receiver / dryer 26, from the receiver / dryer 26 to the thermal expansion valve 28, from the thermal expansion valve 28 to the cooler 30, from the cooler 30 back to the thermal expansion valve 28, and from the thermal expansion valve 28 back to the compressor 22. The first cooling circuit 20 includes a high-pressure side extending from the output of the compressor 22, through the condenser 24 and the receiver / dryer 26, and to the input side of the thermal expansion valve 28. The first cooling circuit 20 also includes a low-pressure side extending from the input side of the thermal expansion valve 28, through the cooler 30 and the output side of the thermal expansion valve 28, and to the input side of the compressor 22.

[0014] The cooler 30 may be configured to absorb heat from the battery 14 and transfer the heat to the coolant or refrigerant within the first cooling loop 20. The cooler 30 may be a cold plate in contact with the battery 14, or may be a cold plate that absorbs heat from a secondary coolant loop configured to cool the battery 14. The secondary coolant loop may include a liquid, such as water or ethylene glycol, that absorbs heat from the battery 14. Alternatively, the cooler may be an evaporator including a coil. The battery 14 may be cooled by directing air across the coil of the evaporator (which will transfer heat from the air to the coolant or refrigerant in the first cooling loop 20) and then directing the same air across the battery 14. The air may be directed through the evaporator and across the battery by a fan or blower. Once the cooler 30 has transferred the heat to the coolant or refrigerant, the coolant or refrigerant will then pass through the compressor 22 and arrive at the condenser 24, where the heat will then be discharged to the surrounding environment. The condenser 24 may include a coil. The cooling system 16 may include a fan or blower that directs air across the coils of the condenser 24 to transfer heat from the coolant or refrigerant to the surrounding environment.

[0015] Alternatively, the cooler 30 may be configured to cool some other system in the vehicle 10 in addition to the battery 14. For example, the cooler 30 may be configured to cool a traction motor in an electric or hybrid vehicle, an inverter in an electric or hybrid vehicle, any of the power electronics in the vehicle, a transmission including transmission electronics and / or transmission fluid, a turbocharger, a supercharger, a fuel cell exhaust water condenser, diesel fuel or engine oil in a diesel operated vehicle. This list is not meant to be exhaustive, and it should be understood that the cooler 30 may be used to cool any auxiliary system in the vehicle 10 that may require additional cooling.

[0016] The cooling system 16 includes a second cooling (or refrigerant) circuit 32. The second cooling circuit 32 is connected to the first cooling circuit 20 and extends from the input side (or high pressure side) of the thermal expansion valve 28 and the cooler 30 to the output side (or low pressure side) of the thermal expansion valve 28 and the cooler 30. The second cooling circuit 32 includes a second shut-off valve 34, a second thermal expansion valve (or optionally a second electric expansion valve) 36, an evaporator 38 (which may be referred to as a second heat exchanger), and an internal heat exchanger 40. The second shut-off valve 34 may be located between the first cooling circuit 20 and the second thermal expansion valve 36 on the input side of the second thermal expansion valve 36. The second shut-off valve 34 may be configured to block the flow of coolant or refrigerant within the second cooling circuit 32.

[0017] The coolant or refrigerant in the second cooling circuit 32 flows from the input side of the thermal expansion valve 28 of the first cooling circuit 20 (or the high pressure side of the first cooling circuit 20) through the internal heat exchanger 40 to the second thermal expansion valve 36, flows from the second thermal expansion valve 36 to the evaporator 38, flows from the evaporator 38 back to the second thermal expansion valve 36, and flows from the second thermal expansion valve 36 through the internal heat exchanger 40 to the output side of the thermal expansion valve 28 of the first cooling circuit 20 (or the low pressure side of the first cooling circuit 20). The second cooling circuit 32 includes a high pressure side extending from the input side of the thermal expansion valve 28 of the first cooling circuit 20 (or the high pressure side of the first cooling circuit 20) to the input side of the second thermal expansion valve 36. The second cooling circuit 32 also includes a low pressure side extending from the input side of the second thermal expansion valve 36, through the evaporator 38 and the output side of the second thermal expansion valve 36, and to the output side of the thermal expansion valve 28 of the first cooling circuit 20 (or the low pressure side of the first cooling circuit 20).

[0018] The evaporator 38 can be configured to cool the cabin 12. More specifically, the evaporator 38 can be configured to cool the first portion 12' of the cabin (e.g., the front portion of the cabin 12). The evaporator 38 can include a coil. The first portion 12' of the cabin can be cooled by directing air across the coil of the evaporator 38 (which will transfer heat from the air to the coolant or refrigerant in the second cooling circuit 32) and then directing the same air into the first portion 12' of the cabin. The air can be directed through the evaporator 38 and into the first portion 12' of the cabin by a fan or blower. Once the evaporator 38 has transferred heat to the coolant or refrigerant, the coolant or refrigerant will then return to the first cooling circuit 20, through the compressor 22 and onto the condenser 24, where the heat will then be discharged to the surrounding environment.

[0019] The cooling system 16 may include a third cooling (or refrigerant) circuit 42. The third cooling circuit 42 is connected to the second cooling circuit 32 and extends from the input side of the second thermal expansion valve 36 and the evaporator 38 (or the high pressure side of the second cooling circuit 32) to the output side of the second thermal expansion valve 36 and the evaporator 38 (or the low pressure side of the second cooling circuit 32). The third cooling circuit 42 includes a third shut-off valve 44, a third thermal expansion valve (or optionally a third electric expansion valve) 46, and a second evaporator 48 (which may be referred to as a third heat exchanger). The third shut-off valve 44 may be located between the second cooling circuit 32 and the third thermal expansion valve 46 on the input side of the third thermal expansion valve 46. The third shut-off valve 44 may be configured to block the flow of coolant or refrigerant within the third cooling circuit 42.

[0020] The coolant or refrigerant in the third cooling circuit 42 flows from the input side of the second thermal expansion valve 36 of the second cooling circuit 32 (or the high-pressure side of the second cooling circuit 32) to the third shut-off valve 44, from the third shut-off valve 44 to the third thermal expansion valve 46, from the third thermal expansion valve 46 to the second evaporator 48, from the second evaporator 48 back to the third thermal expansion valve 46, and from the third thermal expansion valve 46 to the internal heat exchanger 40 and the output side of the second thermal expansion valve 36 of the second cooling circuit 32 (or the low-pressure side of the second cooling circuit 32). The third cooling circuit 42 includes a high-pressure side extending from the input side of the second thermal expansion valve 36 of the second cooling circuit 32 (or the high-pressure side of the second cooling circuit 32) to the input side of the third thermal expansion valve 46. The third cooling circuit 42 also includes a low-pressure side, which extends from the input side of the third thermal expansion valve 46 through the second evaporator 48 and the output side of the third thermal expansion valve 46, and reaches the output side of the second thermal expansion valve 36 of the second cooling circuit 32 (or the low-pressure side of the second cooling circuit 32).

[0021] The second evaporator 48 can be configured to cool the vehicle cabin 12. More specifically, the second evaporator 48 can be configured to cool a second portion 12" of the vehicle cabin (e.g., a rear portion of the vehicle cabin 12). The second evaporator 48 can include a coil. The second portion 12" of the vehicle cabin can be cooled by directing air across the coil of the second evaporator 48 (which will transfer heat from the air to the coolant or refrigerant in the third cooling circuit 42) and then directing the same air into the second portion 12" of the vehicle cabin. The air can be directed through the second evaporator 48 and into the second portion 12" of the vehicle cabin by a fan or blower. Once the second evaporator 48 has transferred heat to the coolant or refrigerant, the coolant or refrigerant will then return to the first cooling circuit 20 via the second cooling circuit 32, through the compressor 22 and to the condenser 24, where the heat will then be discharged to the surrounding environment.

[0022] The controller 18 may communicate with the compressor 22, the thermal expansion valve 28 (including the shutoff valve of the first cooling circuit 20), the second shutoff valve 34, the second thermal expansion valve 36, the third shutoff valve 44, and the third thermal expansion valve 46. The controller 18 may also communicate with various user controls and / or sensors (such as temperature sensors) that direct or command the cooling system 16 to cool the cabin 12 (or a portion thereof), the battery 14, or any other auxiliary system connected to the cooling system 16. The cooling system 16 may also include a pressure sensor 50 that measures the coolant or refrigerant pressure on the high pressure side of the first cooling circuit 20. The pressure sensor 50 may be located anywhere on the high pressure side of the first cooling circuit 20. For example, the pressure sensor may be located at the discharge or output of the compressor 22 (as shown), on either side of the condenser 24, or on either side of the receiver / dryer 26. The pressure of the coolant or refrigerant at the output of the compressor is then communicated to the controller 18 by the pressure sensor 50.

[0023] During the mode in which the cooler 30 operates alone to cool the battery 14 (or other systems that the cooler 30 may be configured to cool), the second shutoff valve 34 and the third shutoff valve 44 will be closed so that the evaporator 38 and the second evaporator 48 will not operate to cool the cabin 12 or any portion thereof. It should also be noted that when the cooler 30 is operating alone, the shutoff valve in the first cooling circuit 20 (which may be integral with the thermal expansion valve 28) will be open and the compressor 22 will be operating. In the case of the cooler 30 operating alone, excess coolant or refrigerant may be drawn into the first cooling circuit 20 from the high and low pressure sides of the second and third cooling circuits 32 and 42 downstream of the second and third shutoff valves 34 and 44. Excess coolant or refrigerant may cause the pressure at the discharge or output port of the compressor 22 to exceed the discharge pressure limit (which may also be referred to as a shutoff threshold). In this case, the compressor 22 may be automatically powered off by the controller 18 to protect the inverter in the electric compressor from drawing too much current and overheating. This may be problematic if compressor 22 is shut down while battery 14 (or other system that chiller 30 may be configured to cool) still requires cooling.

[0024] To prevent the compressor 22 from shutting down during the mode in which the chiller 30 is operated alone, the controller 18 may be programmed to close the second shutoff valve 34 and intermittently pulse open the second shutoff valve 34. Intermittently pulsing open the second shutoff valve 34 will reduce the pressure of the coolant or refrigerant within the first cooling circuit 20 (and more specifically, the pressure of the coolant or refrigerant at the discharge or output of the compressor 22) by causing excess coolant or refrigerant to flow out of the first cooling circuit 20 and back into the second cooling circuit 32 and / or the third cooling circuit 42. Intermittently pulsing open the second shutoff valve 34 may refer to occasionally opening the second shutoff valve 34 at regular or irregular time intervals for a short period of time, followed by re-closing the second shutoff valve 34, whenever the cooling system 16 is commanded to operate the chiller 30 alone.

[0025] The second shut-off valve 34 may be pulsed open at regular, predetermined, evenly spaced time intervals while the cooling system 16 is commanded to operate the chiller 30 alone. Each time the second shut-off valve 34 is pulsed open, the second shut-off valve 34 may remain open for a predetermined period of time. The timing and / or duration of pulsing the second shut-off valve 34 may correspond to a predetermined time and / or duration that prevents the first cooling circuit 20 from being overfilled with coolant or refrigerant to a point at which liquid coolant or refrigerant (as opposed to gaseous coolant or refrigerant) begins to enter the compressor 22 from the input side (or low pressure side) of the first cooling circuit 20.

[0026] Alternatively, the second shut-off valve 34 may be pulsed open whenever the pressure of the refrigerant or coolant at the discharge or output of the compressor 22 exceeds a first threshold. The first threshold may be less than a shut-off threshold for the compressor 22. The first threshold is set and / or adjusted based on the ambient temperature surrounding the vehicle and the rotational speed of the compressor 22. Once the second shut-off valve 34 has been pulsed open in response to the output or discharge pressure of the compressor 22 exceeding the first threshold, the second shut-off valve 34 may remain open for a predetermined period of time or may remain open until the discharge pressure of the compressor 22 drops below a second threshold that is less than the first threshold. The second threshold may correspond to a pressure of the coolant or refrigerant at the discharge or output of the compressor 22 that is low enough that the compressor 22 is unlikely to be powered off. It should be noted that intermittently pulsing the shut-off valve open to relieve pressure in a first cooling or refrigerant circuit of the cooling system is applicable to any cooling system having two or more cooling circuits. For example, if in Figure 2 If the third cooling circuit 42 is eliminated, the pressure in the first cooling circuit 20 can be relieved by intermittently pulsing the second shut-off valve 34 to allow coolant to flow from the first cooling circuit 20 to the second cooling circuit 32 only during a mode in which the cooler 30 is operating alone (in which the second shut-off valve 34 is closed so that the evaporator 38 is not operating).

[0027] The words used in the specification are descriptive rather than limiting, and it should be understood that various changes may be made without departing from the spirit and scope of the present disclosure. As previously mentioned, the features of the various embodiments may be combined to form other embodiments that may not be explicitly described or shown. Although various embodiments may be described as providing advantages or being superior to 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 the desired overall system properties, depending on the specific application and implementation. Therefore, embodiments described as being less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the present disclosure and may be desirable for specific applications.

[0028] According to the present invention, a vehicle is provided, the vehicle having: a first cooling circuit, the first cooling circuit including a compressor and a cooler; a second cooling circuit, the second cooling circuit including a valve and an evaporator, and extending from an input side to an output side of the cooler on the first circuit; and a controller, the controller being programmed to close the valve in response to operation of the cooler rather than the evaporator and to intermittently pulse open the valve whenever the discharge pressure of the compressor exceeds a first threshold.

[0029] According to an embodiment, the valve is arranged in the second circuit between the evaporator and the input side of the first circuit.

[0030] According to an embodiment, the controller is further programmed to, in response to each pulsed opening of the valve, close the valve when the discharge pressure of the compressor drops below a second threshold value that is less than the first threshold value.

[0031] According to an embodiment, the compressor is configured to be de-energized in response to the discharge pressure of the compressor exceeding a shut-down threshold greater than the first threshold.

[0032] According to an embodiment, the invention is also characterized by a traction battery and wherein the cooler is configured to cool the traction battery.

[0033] According to an embodiment, the invention also features a vehicle cabin, and wherein the evaporator is configured to cool the vehicle cabin.

[0034] According to the present invention, a vehicle cooling system is provided, the vehicle cooling system having: a first refrigerant circuit, the first refrigerant circuit including a first heat exchanger; a second refrigerant circuit, the second refrigerant circuit including a valve and a second heat exchanger and extending from a high-pressure side of the first circuit to a low-pressure side, the high-pressure side and the low-pressure side being on opposite sides of the first heat exchanger; and a controller, the controller being programmed to close and intermittently pulse open the valve in response to operation of the first heat exchanger but not the second heat exchanger.

[0035] According to an embodiment, the valve is pulsed open intermittently at regular time intervals.

[0036] According to an embodiment, each time the valve is pulsed open, the valve remains open for a predetermined period of time.

[0037] According to an embodiment, the valve is arranged in the second refrigerant circuit between the second heat exchanger and the high-pressure side of the first circuit.

[0038] According to an embodiment, the first refrigerant circuit includes a compressor, and the controller is further programmed to intermittently pulse open the valve whenever a discharge pressure of the compressor exceeds a first threshold in response to operation of the first heat exchanger but not the second heat exchanger.

[0039] According to an embodiment, the controller is further programmed to, in response to each pulsed opening of the valve, close the valve when the discharge pressure of the compressor drops below a second threshold value that is less than the first threshold value.

[0040] According to an embodiment, the first heat exchanger is configured to cool a vehicle traction battery.

[0041] According to an embodiment, the second heat exchanger is configured to cool a vehicle cabin.

[0042] According to the present invention, a vehicle is provided, the vehicle having: a first refrigerant circuit; the first refrigerant circuit includes a cooler; a second refrigerant circuit, the second refrigerant circuit includes an evaporator and extends from the input side of the cooler on the first circuit to the output side; a valve, the valve is arranged in the second circuit, between the evaporator and the input side; and a controller, the controller is programmed to close and intermittently pulse open the valve in response to operation of the cooler rather than the evaporator.

[0043] According to an embodiment, the valve is pulsed open intermittently at regular time intervals.

[0044] According to an embodiment, each time the valve is pulsed open, the valve remains open for a predetermined period of time.

[0045] According to an embodiment, the first refrigerant circuit includes a compressor, and the controller is further programmed to intermittently pulse open whenever a discharge pressure of the compressor exceeds a first threshold in response to operation of the chiller instead of the evaporator.

[0046] According to an embodiment, the controller is further programmed to, in response to each pulsed opening of the valve, close the valve when the discharge pressure of the compressor drops below a second threshold value that is less than the first threshold value.

[0047] According to an embodiment, the compressor is configured to be de-energized in response to the discharge pressure of the compressor exceeding a shut-down threshold greater than the first threshold.

Claims

1. A vehicle, comprising: a first cooling circuit, the first cooling circuit comprising a compressor and a cooler; a second cooling circuit comprising a valve and an evaporator and extending from an input side to an output side of the cooler on the first cooling circuit; as well as A controller is configured to close the valve and intermittently pulse open the valve each time a discharge pressure of the compressor exceeds a first threshold in response to operation of the chiller but not the evaporator. 2 . The vehicle of claim 1 , wherein the valve is disposed within the second cooling circuit between the evaporator and an input side of the first cooling circuit.

3. The vehicle of claim 1 wherein the controller is further configured to close the valve in response to each pulsed opening of the valve when the discharge pressure of the compressor drops below a second threshold that is less than the first threshold. 4 . The vehicle of claim 1 , wherein the compressor is configured to de-energize in response to the discharge pressure of the compressor exceeding a shut-off threshold that is greater than the first threshold.

5. A vehicle cooling system, comprising: a first refrigerant circuit, the first refrigerant circuit comprising a first heat exchanger; a second refrigerant circuit including a valve and a second heat exchanger and extending from a high pressure side to a low pressure side of the first refrigerant circuit, the high pressure side and the low pressure side being on opposite sides of the first heat exchanger; as well as a controller configured to close and intermittently pulse open the valve in response to operation of the first heat exchanger but not the second heat exchanger, wherein the valve is pulsed open intermittently at regular time intervals; and / or each time the valve is pulsed open, the valve remains open for a predetermined period of time.

6. The system of claim 5, wherein the valve is disposed within the second refrigerant circuit between the second heat exchanger and the high pressure side of the first refrigerant circuit.

7. The system of claim 5, wherein the first refrigerant circuit includes a compressor and the controller is further configured to intermittently pulse open the valve whenever a discharge pressure of the compressor exceeds a first threshold in response to operation of the first heat exchanger but not the second heat exchanger.

8. The system of claim 7, wherein the controller is further configured to close the valve in response to each pulsed opening of the valve when the discharge pressure of the compressor drops below a second threshold that is less than the first threshold.

9. The system of claim 5, wherein the first heat exchanger is configured to cool a vehicle traction battery.

10. The system of claim 5, wherein the second heat exchanger is configured to cool a vehicle cabin.

11. A vehicle, comprising: a first refrigerant circuit, the first refrigerant circuit comprising a cooler; a second refrigerant circuit including an evaporator and extending from an input side to an output side of the cooler on the first refrigerant circuit; a valve disposed in the second refrigerant circuit between the evaporator and an input side; as well as A controller is configured to close and intermittently pulse open the valve in response to operation of the chiller but not the evaporator.

12. The vehicle of claim 11 wherein each time the valve is pulsed open, the valve remains open for a predetermined period of time.

13. The vehicle of claim 11 wherein the first refrigerant circuit includes a compressor and the controller is further configured to intermittently pulse open whenever a discharge pressure of the compressor exceeds a first threshold in response to operation of the cooler instead of the evaporator.

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