Method for detecting and mitigating freezing of external heat exchanger of automobile heat pump system

Abstract

The invention provides a method for detecting and mitigating freezing of an external heat exchanger of an automobile heat pump system. A method of detecting and mitigating icing of an external heat exchanger in an electric vehicle including a heat pump. Various heat sources may be utilized to deice the external heat exchanger of the heat pump. The heat source may include one or more of a vehicle electronics, a high voltage ("HV") battery, and an HV coolant heater. Predefined criteria may be utilized to determine the action to take to deice and / or prevent icing of the external heat exchanger.

Description

[0001] Cross-references to related applications

[0002] This application is a partial continuation to U.S. Patent Application No. 17 / 740,593, filed May 10, 2022, entitled “VAPOR INJECTION HEAT PUMP”, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to vehicle heat exchangers, and more specifically to a method for mitigating icing of external heat exchangers. Background Technology

[0004] Various types of heat pumps have been developed for use in motor vehicles. Heat pumps may include external heat exchangers. Summary of the Invention

[0005] One aspect of this disclosure is a method for de-icing an external heat exchanger of a heat pump in an electric vehicle having a high-voltage (traction) battery that supplies power to one or more electric motors moving the vehicle, wherein the heat pump is configured to heat the passenger compartment of the electric vehicle. The method includes implementing a first de-icing mode if the ambient air temperature is at or above a first predefined temperature greater than the freezing point. The first de-icing mode includes shutting down the heat pump and using coolant from a high-voltage heater to heat the passenger compartment and / or the high-voltage battery. The method further includes implementing a second de-icing mode if the high-voltage battery is acceptable for cooling according to predefined criteria. The second de-icing mode includes cooling the high-voltage battery and heating the external heat exchanger by utilizing the heat from the high-voltage battery by allowing the coolant, already heated by the high-voltage battery, to flow through the external heat exchanger. The method further includes implementing a third de-icing mode if the high-voltage battery is not acceptable for cooling according to predefined criteria and if the high-voltage battery temperature is greater than a second predefined temperature greater than the freezing point. The third de-icing mode includes shutting off the heat pump, using a high-pressure coolant heater to heat the electric vehicle's cabin, and circulating coolant through a combined fluid loop between the high-voltage battery and an external heat exchanger to heat the external heat exchanger. The method also includes implementing a fourth de-icing mode if the high-voltage battery cannot be cooled according to predefined criteria and if the high-voltage battery temperature is not greater than a second predefined temperature. The fourth de-icing mode includes shutting off the heat pump, using a high-pressure coolant heater to heat the cabin, and circulating coolant between the vehicle's power electronics, the heat pump's water-cooled condenser, and the external heat exchanger to heat the external heat exchanger.

[0006] - The first predefined temperature can be 3℃.

[0007] The electric vehicle may include an electric fan and grille louvers, which may be actuated to control airflow above the external heat exchanger, and the first de-icing mode may include opening the grille louvers and actuating the electric fan to increase the flow of ambient air above the external heat exchanger.

[0008] - After the external heat exchanger has been de-iced using the first, second, third, or fourth de-icing modes, the method may include opening the grille louvers and actuating the electric fan to dissipate water droplets on the external heat exchanger.

[0009] The method may include determining whether the external heat exchanger is about to freeze during vehicle compartment heating. If the external heat exchanger is about to freeze, the method may include opening the louvers of the external heat exchanger and activating a fan to increase the airflow above the external heat exchanger, and disengaging the steam injection operation of the heat pump, before implementing any of the first, second, third, and fourth de-icing modes.

[0010] - The first mode may include increasing airflow above the external heat exchanger by opening the grille louvers of the external heat exchanger and actuating the electric fan of the external heat exchanger.

[0011] - The second mode may include reducing airflow above the external heat exchanger by closing the grille louvers of the external heat exchanger and actuating the electric fan of the external heat exchanger.

[0012] - The third mode may include reducing airflow above the external heat exchanger by closing the grille louvers of the external heat exchanger and actuating the electric fan of the external heat exchanger.

[0013] - A second predefined temperature above the freezing point can be 3°C to 10°C.

[0014] Another aspect of this disclosure is a method for de-icing an external heat exchanger of a heat pump in an electric vehicle having a high-voltage battery, wherein the heat pump is configured to heat the passenger compartment of the electric vehicle. The method includes implementing a first de-icing mode if a condition satisfying a first predefined criterion is detected. The first de-icing mode includes reducing heat pump output and using heat from a high-pressure coolant heater to heat the passenger compartment and / or the high-voltage battery. The method includes implementing a second de-icing mode if the high-voltage battery is acceptable for cooling according to a predefined criterion. The second de-icing mode includes using heat from the high-voltage battery to heat the external heat exchanger. The method includes implementing a third de-icing mode if the high-voltage battery is not acceptable for cooling according to the predefined criterion, and if the high-voltage battery temperature is greater than a second predefined temperature above the freezing point. The third de-icing mode includes reducing heat pump output, using a high-pressure coolant heater to heat the passenger compartment of the electric vehicle, and circulating coolant through a combined fluid loop between the high-voltage battery and the external heat exchanger to heat the external heat exchanger. The method includes implementing a fourth de-icing mode if the criteria for the first, second, and third de-icing modes are not satisfied. The fourth de-icing mode includes shutting down the heat pump, using high-voltage battery coolant to heat the passenger compartment, and circulating the coolant between the vehicle's power electronics, the heat pump's water-cooled condenser, and the external heat exchanger to heat the external heat exchanger.

[0015] - The first predefined criterion may include an ambient temperature above the freezing point.

[0016] - The second de-icing mode may include allowing coolant already heated by the high-voltage battery to flow through an external heat exchanger.

[0017] - Optionally, the fourth de-icing mode may not be implemented unless the high-voltage battery cannot be cooled according to a predefined standard and the temperature of the high-voltage battery is not greater than the second predefined temperature.

[0018] - The first de-icing mode may include turning off the heat pump.

[0019] - The third de-icing mode may include turning off the heat pump.

[0020] - After implementing the fourth de-icing mode, if the loop cooling temperature is below a predefined threshold, the method may include bypassing the external heat exchanger with coolant and using waste heat from the motor electronics to heat the coolant circulating through the vehicle's power electronics and the water-cooled condenser of the heat pump, and / or operating the vehicle's power electronics in a destructive mode.

[0021] - After implementing the fourth de-icing mode, if the loop cooling temperature is higher than a predefined threshold, the method may include allowing coolant to flow through the external heat exchanger to de-ic the external heat exchanger.

[0022] The electric vehicle may include an electric fan and grille louvers, which may be actuated to control airflow above the external heat exchanger, and the first de-icing mode may include opening the grille louvers and actuating the electric fan to increase the flow of ambient air above the external heat exchanger.

[0023] - After the external heat exchanger has been de-iced using the first, second, third, or fourth de-icing modes, the grille louvers can be opened and the electric fan can be activated to dissipate water droplets on the external heat exchanger.

[0024] The method may include determining whether the external heat exchanger is about to freeze during vehicle compartment heating. If the external heat exchanger is about to freeze, the method may include opening the louvers of the external heat exchanger and activating a fan to increase the airflow above the external heat exchanger, and disengaging the steam injection operation of the heat pump, before implementing any of the first, second, third, and fourth de-icing modes.

[0025] By referring to the following description, claims and drawings, those skilled in the art will further understand and appreciate these and other features, advantages and objectives of the present invention. Attached Figure Description

[0026] In the attached diagram:

[0027] Figure 1 This is a schematic diagram showing the heat flow of a heat pump in heating mode;

[0028] Figure 2 This is a flowchart illustrating the process for determining whether an external heat exchanger is about to freeze; and

[0029] Figure 3 This is a flowchart illustrating a process for mitigating icing of an external heat exchanger according to one aspect of this disclosure. Detailed Implementation

[0030] Reference will now be made in detail to the preferred embodiments of this disclosure, examples of which are illustrated in the accompanying drawings. Where possible, the same reference numerals will be used throughout the drawings to refer to the same or similar parts. In the drawings, structural elements are depicted not to scale, and some parts are enlarged relative to others for emphasis and understanding purposes.

[0031] Detailed embodiments of the present invention are disclosed herein as requested; however, it should be understood that the disclosed embodiments are merely examples of different and alternative forms in which the invention may be embodied. The accompanying drawings are not necessarily detailed designs; some schematic diagrams may be enlarged or minimized to show a functional overview. Therefore, the specific structural and functional details disclosed herein are not to be construed as limiting, but only as representative bases for teaching those skilled in the art to employ the invention in various ways.

[0032] For the purposes of this description, the terms “up,” “down,” “right,” “left,” “back,” “front,” “vertical,” “horizontal,” and their derivatives should refer to, for example, the following: Figure 1 The concept of orientation is used. However, it should be understood that the concept may present various alternative orientations unless explicitly stated otherwise. It should also be understood that the specific apparatus and processes shown in the accompanying drawings and described in the following specification are merely exemplary embodiments of the inventive concept defined in the appended claims. Therefore, unless otherwise expressly stated in the claims, the specific dimensions and other physical characteristics relating to the embodiments disclosed herein should not be considered limiting.

[0033] The embodiments shown here exist primarily in combinations of method steps and equipment components related to heat pumps. Therefore, equipment components and method steps have been indicated by conventional symbols in the accompanying drawings where appropriate, illustrating only those specific details relevant to understanding embodiments of this disclosure, so as not to obscure the disclosure with details readily apparent to those skilled in the art who benefit from the description herein. Furthermore, the same reference numerals denote the same elements in the specification and drawings.

[0034] As used herein, the terms “or” and “and / or” when used with two or more listed items mean that any one of the listed items may be used alone, or any combination of two or more listed items may be used. For example, if a composition or device is described as containing or including components A, B, or C, the composition or device may contain (including): A only; B only; C only; a combination of A and B; a combination of A and C; a combination of B and C; or a combination of A, B, and C. If a composition or device is described as containing or including components A or B or C, the composition or device may contain (including): A only; B only; C only; a combination of A and B; a combination of A and C; a combination of B and C; or a combination of A, B, and C.

[0035] In this document, relational terms such as first and second, top and bottom are used individually to distinguish one entity or action from another, without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprising,” “including,” or any other variation thereof are intended to cover non-exclusive inclusion, such that a process, method, article of manufacture, or apparatus that comprises a list of elements includes not only those elements but may also include other elements not expressly listed or inherent to such process, method, article of manufacture, or apparatus. Without further constraints, an element preceded by “comprising…” does not exclude the presence of additional identical elements in the process, method, article of manufacture, or apparatus that includes said element.

[0036] As used herein, the term "about" means that a quantity, size, formulation, parameter, and other quantity and characteristic is not precise, nor need it to be precise, but may be approximate and / or larger or smaller as required to reflect tolerances, conversion factors, rounding, measurement errors, and other factors known to those skilled in the art. When the term "about" is used to describe an endpoint of a value or range, this disclosure should be understood to include both the specific value and the mentioned endpoint. Whether or not the endpoints of numerical values ​​or ranges in this specification are referred to as "about," the endpoints are intended to include both embodiments: one modified by "about" and one not modified by "about." It should also be understood that each endpoint of a range is significant both in relation to and independent of another endpoint.

[0037] As used herein, the terms “substantially,” “basically,” and variations thereof are intended to indicate that the described feature is equal to or approximately equal to a value or description. For example, a “substantially planar” surface is intended to indicate a planar or approximately planar surface. Additionally, “substantially” is intended to mean that two values ​​are equal or approximately equal. In some embodiments, “substantially” may indicate that the values ​​are within about 10% of each other, such as within about 5% of each other, or within about 2% of each other.

[0038] Unless explicitly indicated otherwise, as used herein, the terms “the,” “an,” or “a” mean “at least one” and should not be limited to “only one.” Thus, for example, unless the context clearly indicates otherwise, references to “component” include embodiments having two or more such components.

[0039] Typically, battery electric vehicles (BEVs) do not have an internal combustion engine and therefore have alternative methods of providing heat using heat pump systems and / or electric heaters. The air conditioning cycle, or refrigerant cycle, has a cold heat exchanger and a hot heat exchanger. Conventional air conditioning uses the cold heat exchanger to cool passengers, while the hot heat exchanger is exposed to outside air. For BEVs, the refrigerant cycle can be used as a conventional air conditioning system to cool the cabin and battery. The refrigerant cycle may also include a heat pump system that uses the hot side to heat the cabin, defrost the windshield, and heat the HV battery, while the cold external heat exchanger can be exposed to outside (ambient) air. If the cold (external) heat exchanger is exposed to moisture, where frost or ice begins to form on the external heat exchanger, preventative measures may be necessary. These preventative measures may include warming the external heat exchanger to thaw the frost or ice into liquid, after which the liquid water can be blown out (removed) from the external heat exchanger.

[0040] Icing on external heat exchangers can cause problems with compressor operation and system heat dissipation capacity (reduced heat output). When external heat exchangers are de-iced, the system's normal heating function cannot occur, which may result in the use of less efficient electric heaters. Delayed de-icing (no attribute / performance loss) and optimized de-icing (time and heat source) can provide a better passenger experience.

[0041] In addition to preventing excessive ice / frost on external heat exchangers, this disclosure also provides a method for preventing excessive thermal cycling of external heat exchangers. This disclosure may include determining how quickly the external heat exchanger freezes, and may also include maintaining output to meet heating demands. A method according to one aspect of this disclosure reduces or eliminates the buildup of ice / frost on external heat exchangers without cycling the levels too frequently or with too large a temperature increment, in a manner that could degrade components of the system.

[0042] This disclosure also provides de-icing using an optimal heat source. As discussed in more detail below, the system can be configured to determine, based on operating conditions, whether an acceptable form of heat is available and which heat source is optimal for the de-icing purpose of the external heat exchanger. Typically, the external heat exchanger can defrost rapidly under certain conditions (the coldest ambient air temperature, but with the lowest total moisture level on the external heat exchanger). However, in the presence of mild ambient conditions, road splashes, rainwater, or sludge may freeze when the HV battery cooler and / or LTR (low-temperature radiator) are operating at sub-zero temperatures (i.e., where heat may be more easily “trapped” in the coolant, thus delaying de-icing without compromising passenger comfort). Exemplary heat sources are the powertrain / electronics (including “damaged” versions if the vehicle is equipped with these components), the HV battery, and the HV coolant heater.

[0043] refer toFigure 1 According to one aspect of this disclosure, system 1 includes an external heat exchanger 5, which includes active grille louvers and an electrically driven fan 4. In use, outside air 3 can flow through the external heat exchanger 5 to provide heat transfer, and the active grille louvers and electrically driven fan 4 can be used to control the flow of outside air 3. Arrow 2 generally indicates the heat flow from outside (ambient) air 3 to the external heat exchanger 5.

[0044] System 1 also includes a heat pump 8, which can be actuated to provide heat 9 to a water-cooled condenser 10. Heat from the water-cooled condenser 10 can be transferred to the high-voltage battery 16, the cabin heater 18, and the electrical (motor) electronics 20, as indicated by arrows 12, 13, and 14. Typically, the heat flow corresponding to arrows 6, 9, 12, 13, and 14 can be achieved using one or more coolant circuits, as described in U.S. Patent No. 11,906,213 to Brown et al., published February 20, 2024, and / or U.S. Patent No. 10,190,812 to Ragazzi, published January 29, 2019, the entire contents of each of which are incorporated herein by reference. System 1 may optionally include one or more coolant circuits 17, 19, and 21, which allow heat to be transferred from the HV battery 16, the cabin heater 18, and the electrical electronics 20 to an external heat exchanger 5, respectively. Coolant circuits 17, 19, and 21 may include conduits for fluid in a loop form, the loop allowing coolant to flow through the heat exchangers of the HV battery 16, cabin heater 18, and power electronics 20, and through the external heat exchanger 5, thereby selectively transferring heat from the HV battery 16 and / or cabin heater 18 and / or power electronics 20 to the external heat exchanger 5. Controller 15 may be configured to selectively actuate pumps and / or valves (not shown) of one or more of coolant circuits 17 and / or 19 and / or 21 in any combination as needed to control coolant flow based on operating conditions to transfer heat to (or from) the external heat exchanger 5. System 1 may also include a cryogenic external radiator 7 exposed to ambient air. The cryogenic external radiator 7 may include an air-to-liquid (coolant) heat exchanger. The cryogenic radiator 7 may be operatively connected to the heat pump 8 via coolant circuit 18. If heat pump 8 is off, cryogenic radiator 7 can be used to cool HV battery 16 and / or power electronic device 20 via coolant circuits 24 and 25, respectively. Coolant circuits 18, 24, and 25 may include conduits, valves, and one or more pumps (not shown), which may be selectively actuated by controller 15 to allow coolant to flow through coolant circuits 18, 24, and 25 as needed based on operating conditions and the methods of this disclosure. It should be understood that cryogenic radiator 7 and coolant circuits 17, 18, 19, 21, 24, and 25 are optional, and system 1 may utilize one or more of the coolant circuits disclosed in the aforementioned patent application to provide the heat transfer function of one or more of circuits 17, 18, 19, 21, 24, and 25. Therefore, system 1 may include only one of coolant circuits 17, 18, 19, 21, 24, and 25, or system 1 may include selected circuits in any combination.

[0045] System 1 may include a controller 15 operatively connectable to various components, as shown by dashed lines 22A-22D. It should be understood that controller 15 may include one or more separate controllers in hardware and / or software form that can be integrated with various vehicle controllers and systems.

[0046] Further reference Figure 2 Process 30 can be used to detect that the external heat exchanger 5 is about to freeze, thereby monitoring the situation to determine whether further action is needed to prevent the external heat exchanger 5 from freezing or to defrost it. At 32, the external heat exchanger is detected to be about to freeze during cabin heating. Imminent freezing and / or freezing can be detected by monitoring the radiator outlet temperature (i.e., the temperature of the coolant leaving the low-temperature radiator 7) relative to the outside air temperature during heat pump operation. The threshold for impending freezing may differ from the threshold for detecting freezing. Detected freezing occurs when the difference between the ambient air temperature and the radiator outlet temperature is very large. Imminent freezing detection occurs when the difference between the ambient temperature and the LTR (radiator 7) outlet temperature is slightly smaller than that for detected freezing. After impminent freezing is detected at 32, a timer is started at 34. At step 36, if system 1 is a dual-compressor system, the process allows only a single compressor to operate, as shown at 38. At point 40, the active grille louvers of the external heat exchanger 5 are opened, and the electronically driven fan is actuated to increase airflow above the external heat exchanger 5. At point 42, the steam injection operation can be exited. At point 44, the process determines whether the external temperature of the external heat exchanger 5 is greater than X degrees Celsius + hysteresis or whether a timer has expired (e.g., the external air temperature is greater than a calibrable threshold). It should be understood that hysteresis typically refers to the temperature difference between "on" and "off" (e.g., 1, 2, 3, 4, 5, 10 degrees Celsius) to prevent over-circulation. If "No" is found at point 44, the process returns to step 40. If "Yes" is found at point 44, the process ends at point 46.

[0047] Further reference Figure 3The de-icing process 54 for the external heat exchanger 5 may include actions in modes 56, 60, 64, 66, 70, and 72 based on detected operating conditions 54, 58, 62, and 68. At 52, if it is detected that the external heat exchanger 5 is about to freeze during cabin heating, process 50 begins. At 54, if the ambient temperature is greater than or equal to “T1” (e.g., 3°C), the process implements a first mode or a first set of actions 56, which may include one or more of the following: 1) cabin and / or battery heating using an HV coolant heater during heat pump shutdown and / or 3) operation of active grille louvers and / or electrically driven fans to defrost the external heat exchanger 5 via ambient air 3. It should be understood that the heat pump does not necessarily need to be completely shut down, and the heat pump can operate at a reduced level.

[0048] If the ambient temperature at point 54 is not greater than or equal to T1, then at point 58, the process determines whether the HV battery 16 is acceptable for cooling according to predefined criteria. Predefined criteria may include battery temperature and battery state of charge (SOC). A lookup table using the SOC and temperature as inputs can be used to arbitrate whether battery cooling is acceptable. Additional control inputs / factors may include ambient air temperature and battery charge usage. If the HV battery 16 is acceptable for cooling at point 58, the process proceeds to a second mode or a second set of actions 60, which may include one or more of the following: 1) cooling the HV battery to provide heat for de-icing the external heat exchanger and / or 2) allowing warm or hot coolant to flow through the external heat exchanger 5 and / or 3) closing the active grille louvers and / or shutting off the electrically driven fan to minimize ambient air flow over the external heat exchanger 5 during de-icing.

[0049] If the HV battery cannot be cooled at point 58, the process continues to point 62. At point 62, the system (e.g., controller 15) determines whether the temperature of the HV battery 16 is greater than 0°C plus an offset “T2”, where T2 is a calibrable temperature (T2 refers to the HV battery temperature).

[0050] If the HV battery temperature at point 62 is greater than 0°C plus an offset T2, a third action or mode 64 is implemented. The third mode 64 may include one or more of the following: 1) shutting down the heat pump (or reducing heat pump output) and / or 2) using the HV coolant heater for cabin heating and / or 3) circulating coolant through the HV battery 16 and external heat exchanger 5 in the combined circuit to defrost the external heat exchanger 5 and / or 4) closing the active grille louvers and / or shutting down the electric drive fan. The combined circuit combines the HV battery and the cryogenic radiator 7 into the same continuous coolant circuit 24 to allow coolant to flow between the HV battery 16 and the cryogenic radiator 7. Generally, a "combined circuit" refers to circulation within a coolant loop or coolant flow path. A loop is a loop or flow path through which coolant flows in a certain operating mode. Having the HV battery 16 and the cryogenic radiator 7 in the same circuit 24 provides coolant circulation between the HV battery 16 and the cryogenic radiator 7.

[0051] If the HV battery temperature at step 62 is not greater than 0°C plus offset T2, the process continues to the fourth mode or fourth group of actions 66, which may include one or more of the following: 1) turning off the heat pump (or reducing the heat pump output) and / or: 2) using the HV coolant heater for cabin heating and / or: 3) circulating coolant between the power electronics, water-cooled condenser and external heat exchanger 5 and / or: 4) closing the active grille louvers and / or turning off the electronically driven fan.

[0052] Following step 66, at step 68, the process (e.g., controller 15) determines whether the loop cooling temperature is greater than a threshold temperature. The threshold temperature may include a calibrable temperature threshold calibrated for a specific vehicle application. This threshold ensures that the coolant used to defrost the external heat exchanger 5 is warm enough to do so. This threshold temperature value is above and deviates from 0°C. Bypassing the cryogenic radiator 7 or the external heat exchanger 5 redirects the coolant flow around the heat exchanger, thus bypassing it (e.g., using a bypass valve). Bypassing the external heat exchanger 5 prevents heat transfer with the environment and the cryogenic radiator 7, while simultaneously allowing some heat to accumulate in the coolant via lossy modes, etc. When the coolant is warm enough, it flows through the external heat exchanger 5 to defrost it.

[0053] If the coolant temperature in the circuit is not greater than the threshold temperature at step 68, then at step 70, one or more actions are taken. These actions may include: 1) bypassing an external heat exchanger and / or: 2) the power electronics using motor electronics waste heat or a “lossy mode” to accumulate heat in the coolant circuit. A lossy mode typically refers to using motor electronics to generate additional heat. In the case of an electric motor controller for a battery-powered electric vehicle, the electric motor may operate in a manner that generates heat at the components. This heat can be transferred to the flow through motor electronics 20 (Figure 1 The coolant is then transferred to an external heat exchanger 5 for de-icing purposes.

[0054] If the coolant temperature in the loop is higher than the threshold temperature at step 68, then at step 72, the coolant is allowed to flow through the external heat exchanger 5 to thaw the external heat exchanger 5.

[0055] After de-icing at steps 56, 60, 64, or 72, the process continues to step 74, where the active grille louvers are opened and the electronically driven fan is actuated to blow water droplets away from the heat exchanger 5. Then, as shown at step 76, operation of the heat pump 8 can be resumed, and process 50 ends at 78.

[0056] External heat exchanger 5 may collect frost or ice from moisture contained in the road surface or ambient air, which may obstruct airflow or, under extreme conditions, degrade the heat exchanger 5. This disclosure provides a method for detecting and preventing frost formation on external heat exchanger 5 to maintain performance, improve vehicle efficiency, and enhance durability.

[0057] It should be understood that changes and modifications may be made to the foregoing structures and methods without departing from the concept of the invention, and it should also be understood that such concepts are intended to be covered by the following claims unless otherwise expressly stated in their language.

[0058] According to the present invention, a method for de-icing an external heat exchanger of a heat pump in an electric vehicle having a high-voltage battery, wherein the heat pump is configured to heat the passenger compartment of the electric vehicle, the method comprising: implementing a first de-icing mode if the ambient air temperature is at or above a first predefined temperature greater than the freezing point, wherein the first de-icing mode includes shutting down the heat pump and using heat from a high-voltage coolant heater to heat the passenger compartment and / or heat the high-voltage battery; implementing a second de-icing mode if the high-voltage battery is coolable according to a predefined standard, wherein the second de-icing mode includes cooling the high-voltage battery and using heat from the high-voltage battery to heat the external heat exchanger by allowing coolant already heated by the high-voltage battery to flow through the external heat exchanger; and implementing a second de-icing mode if the high-voltage battery is not coolable according to the predefined standard. If cooling is acceptable and the high-voltage battery temperature is greater than a second predefined temperature above freezing, a third de-icing mode is implemented, wherein the third de-icing mode includes shutting off the heat pump, using a high-voltage coolant heater to heat the passenger compartment of the electric vehicle, and circulating coolant through the high-voltage battery and the external heat exchanger in a combined fluid loop to heat the external heat exchanger; and if the high-voltage battery cannot be cooled according to predefined criteria and if the high-voltage battery temperature is not greater than the second predefined temperature, a fourth de-icing mode is implemented, wherein the fourth de-icing mode includes shutting off the heat pump, using high-voltage battery coolant to heat the passenger compartment, and circulating coolant between the vehicle's power electronics, the heat pump's water-cooled condenser, and the external heat exchanger to heat the external heat exchanger.

[0059] In one aspect of the invention, the first predefined temperature is 3°C.

[0060] In one aspect of the invention, the electric vehicle includes an electric fan and grille louvers, the electric fan and grille louvers being actuated to control airflow above the external heat exchanger, and the first de-icing mode includes opening the grille louvers and actuating the electric fan to increase the flow rate of ambient air above the external heat exchanger.

[0061] In one aspect of the invention, the method includes: after the external heat exchanger has been de-iced using one or more of the first de-icing mode, the second de-icing mode, the third de-icing mode, or the fourth de-icing mode, opening the grille louvers and actuating the electric fan to dissipate water droplets on the external heat exchanger.

[0062] In one aspect of the invention, the method includes: determining, using predefined criteria, whether an external heat exchanger is about to freeze during carriage heating; and if the external heat exchanger is about to freeze, before implementing any of the first, second, third, and fourth de-icing modes, 1) opening the louvers of the external heat exchanger and activating an electric fan to increase the airflow above the external heat exchanger, and 2) disengaging the steam injection operation of the heat pump.

[0063] In one aspect of the invention, the first mode includes increasing airflow above the external heat exchanger by opening the grille louvers of the external heat exchanger and actuating the electric fan of the external heat exchanger.

[0064] In one aspect of the invention, the second mode includes reducing airflow above the external heat exchanger by closing the grille louvers of the external heat exchanger and actuating the electric fan of the external heat exchanger.

[0065] In one aspect of the invention, the third mode includes reducing airflow above the external heat exchanger by closing the grille louvers of the external heat exchanger and actuating the electric fan of the external heat exchanger.

[0066] In one aspect of the invention, the second predefined temperature above the freezing point is 3°C-10°C.

[0067] In one aspect of the invention, a method for de-icing an external heat exchanger of a heat pump in an electric vehicle having a high-voltage battery, wherein the heat pump is configured to heat the passenger compartment of the electric vehicle, the method comprising: implementing a first de-icing mode if conditions satisfying a first predefined criterion are detected, wherein the first de-icing mode includes reducing heat pump output and using heat from a high-voltage coolant heater to heat the passenger compartment and / or heat the high-voltage battery; implementing a second de-icing mode if the high-voltage battery is capable of being cooled according to the predefined criterion, wherein the second de-icing mode includes using heat from the high-voltage battery to heat the external heat exchanger; and implementing a second de-icing mode if the high-voltage battery is not capable of being cooled according to the predefined criterion and if the high-voltage battery temperature is greater than a certain value. If the temperature exceeds a second predefined temperature above freezing, a third de-icing mode is implemented, wherein the third de-icing mode includes reducing the heat pump output, using a high-pressure coolant heater to heat the passenger compartment of the electric vehicle, and circulating coolant through the high-voltage battery and the external heat exchanger in a combined fluid loop to heat the external heat exchanger; and if the criteria of the first, second, and third de-icing modes are not met, a fourth de-icing mode is implemented, wherein the fourth de-icing mode includes shutting down the heat pump, using high-pressure battery coolant to heat the passenger compartment, and circulating coolant between the vehicle's power electronics, the heat pump's water-cooled condenser, and the external heat exchanger to heat the external heat exchanger.

[0068] In one aspect of the invention, the first predefined criterion may include a selected ambient temperature above the freezing point.

[0069] In one aspect of the invention, the second de-icing mode includes allowing the coolant, which has been heated by the high-voltage battery, to flow through the external heat exchanger.

[0070] In one aspect of the invention, the fourth de-icing mode is not implemented unless the high-voltage battery cannot be cooled according to a predefined standard and the temperature of the high-voltage battery is not greater than the second predefined temperature.

[0071] In one aspect of the invention, the first de-icing mode includes shutting down the heat pump.

[0072] In one aspect of the invention, the third de-icing mode includes shutting down the heat pump.

[0073] In one aspect of the invention, the method includes: after implementing the fourth de-icing mode, if the loop cooling temperature is below a predefined threshold, causing the coolant to bypass the external heat exchanger and using waste heat from the motor electronics to heat the coolant circulating through the power electronics of the vehicle and the water-cooled condenser of the heat pump, and / or operating the power electronics of the vehicle in a destructive mode.

[0074] In one aspect of the invention, the method includes: after implementing the fourth de-icing mode, if the loop cooling temperature is higher than a predefined threshold, allowing coolant to flow through the external heat exchanger to de-ic the external heat exchanger.

[0075] In one aspect of the invention, the electric vehicle includes an electric fan and grille louvers, the electric fan and grille louvers being actuated to control airflow above the external heat exchanger; and the first de-icing mode includes opening the grille louvers and actuating the electric fan to increase the flow rate of ambient air above the external heat exchanger.

[0076] In one aspect of the invention, the method includes: after the external heat exchanger has been de-iced using the first de-icing mode, the second de-icing mode, the third de-icing mode, or the fourth de-icing mode, opening the grille louvers and actuating the electric fan to dissipate water droplets on the external heat exchanger.

[0077] In one aspect of the invention, the method includes: determining, using predefined criteria, whether an external heat exchanger is about to freeze during carriage heating; if the external heat exchanger is about to freeze, before implementing any of the first, second, third, and fourth de-icing modes, 1) opening the louvers of the external heat exchanger and activating an electric fan to increase the airflow above the external heat exchanger, and 2) disengaging the steam injection operation of the heat pump.

Claims

1. A method for de-icing an external heat exchanger of a heat pump in an electric vehicle having a high-voltage battery, wherein the heat pump is configured to heat the passenger compartment of the electric vehicle, the method comprising: If a condition that meets a first predefined criterion is detected, a first de-icing mode is implemented, wherein the first de-icing mode includes reducing heat pump output and using heat from the high-pressure coolant heater to heat the passenger compartment and / or heat the high-pressure battery; If the high-voltage battery is coolable according to predefined standards, a second de-icing mode is implemented, wherein the second de-icing mode includes using heat from the high-voltage battery to heat the external heat exchanger. If the high-voltage battery cannot be cooled according to predefined criteria and if the high-voltage battery temperature is greater than a second predefined temperature above the freezing point, a third de-icing mode is implemented. This third de-icing mode includes reducing the heat pump output, using a high-pressure coolant heater to heat the passenger compartment of the electric vehicle, and circulating coolant through the high-voltage battery and the external heat exchanger in a combined fluid loop to heat the external heat exchanger. If the criteria for the first, second, and third de-icing modes are not met, a fourth de-icing mode is implemented, wherein the fourth de-icing mode includes shutting down the heat pump, using high-voltage battery coolant to heat the passenger compartment, and circulating the coolant between the vehicle's power electronics, the heat pump's water-cooled condenser, and the external heat exchanger to heat the external heat exchanger.

2. The method of claim 1, wherein: The first predefined criterion can include selected ambient temperatures above the freezing point.

3. The method as claimed in claim 1 or claim 2, wherein: The second de-icing mode includes allowing the coolant, which has been heated by the high-voltage battery, to flow through the external heat exchanger.

4. The method according to any one of claims 1 to 3, wherein: The fourth de-icing mode is not implemented unless the high-voltage battery cannot be cooled according to a predefined standard and the temperature of the high-voltage battery is not greater than the second predefined temperature.

5. The method according to any one of claims 1 to 4, wherein: The first de-icing mode includes turning off the heat pump.

6. The method according to any one of claims 1 to 5, wherein: The third de-icing mode includes shutting down the heat pump.

7. The method according to any one of claims 1 to 6, comprising: After implementing the fourth de-icing mode, if the loop cooling temperature is below a predefined threshold, the coolant is bypassed from the external heat exchanger, and the waste heat from the motor electronics is used to heat the coolant circulating through the vehicle's power electronics and the water-cooled condenser of the heat pump, and / or the vehicle's power electronics are operated in a destructive mode.

8. The method according to any one of claims 1 to 7, comprising: After implementing the fourth de-icing mode, if the loop cooling temperature is higher than a predefined threshold, coolant is allowed to flow through the external heat exchanger to de-ic the external heat exchanger.

9. The method according to any one of claims 1 to 8, wherein: The electric vehicle includes an electric fan and grille louvers, which can be actuated to control airflow above the external heat exchanger. and The first de-icing mode includes opening the grille louvers and actuating the electric fan to increase the airflow above the external heat exchanger.

10. The method according to any one of claims 1 to 9, comprising: After the external heat exchanger has been de-iced using the first, second, third, or fourth de-icing modes, the grille louvers are opened and the electric fan is activated to dissipate water droplets on the external heat exchanger.

11. The method according to any one of claims 1 to 10, comprising: Predefined criteria are used to determine whether the external heat exchanger is about to freeze during the heating of the carriage; If the external heat exchanger is about to freeze, before implementing any of the first, second, third, and fourth de-icing modes: 1) open the louvers of the external heat exchanger and activate the electric fan to increase the airflow above the external heat exchanger, and 2) deactivate the steam injection operation of the heat pump.

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