Vehicle thermal management system

Abstract

This invention relates to a vehicle thermal management system. The object of this invention is to respond to icing in the outdoor heat exchanger under heat pump mode without restricting refrigerant flow to the outdoor heat exchanger, and to prevent instability in refrigerant flow in the refrigerant circulation line due to refrigerant flow restriction to the outdoor heat exchanger, and to prevent deterioration of vehicle interior heating performance due to refrigerant flow instability. To achieve the above object, a vehicle thermal management system includes a heat pump type refrigerant circulation line having a compressor, a high-pressure side heat exchanger, an outdoor heat exchanger, a plurality of expansion valves, and a low-pressure side heat exchanger. The thermal management system includes: a first expansion valve installed upstream of the outdoor heat exchanger; a second expansion valve installed downstream of the outdoor heat exchanger; and a control unit that controls the opening degree of the first and second expansion valves located upstream and downstream of the outdoor heat exchanger based on whether icing occurs in the outdoor heat exchanger under heat pump mode.

Description

Technical Field

[0001] This invention relates to a vehicle thermal management system, and more particularly to a vehicle thermal management system that can respond to icing in the outdoor heat exchanger without restricting the flow of refrigerant to the outdoor heat exchanger when icing occurs in the outdoor heat exchanger under heat pump mode conditions, and can prevent instability of refrigerant flow in the refrigerant circulation line due to restriction of refrigerant flow to the outdoor heat exchanger and the resulting deterioration of heating performance in the vehicle interior. Background Technology

[0002] Examples of environmentally friendly vehicles include electric vehicles, hybrid vehicles, and fuel cell vehicles (collectively referred to as “vehicles”).

[0003] This vehicle is equipped with various thermal management devices. For example, such as... Figure 1 As shown, the thermal management device includes an air conditioner 10 for cooling and heating the vehicle interior and a water-cooled cooling device 20 for cooling the battery B and the electronic component module P.

[0004] The air conditioner 10 is a heat pump type and is equipped with a refrigerant circulation line 12.

[0005] The refrigerant circulation line 12 includes a compressor 12a, a high-pressure side indoor heat exchanger 12b, a first expansion valve 12c, an outdoor heat exchanger 12d, a second expansion valve 12e, a third expansion valve 12f connected in parallel with the second expansion valve 12e, a cooler 12g arranged on the second expansion valve 12e, and a low-pressure side indoor heat exchanger 12h arranged downstream of the third expansion valve 12f.

[0006] In the refrigerant circulation line 12, in air conditioner mode, the first expansion valve 12c is opened, allowing the refrigerant in the compressor 12a to circulate in the following order: high-pressure side indoor heat exchanger 12b, outdoor heat exchanger 12d, second expansion valve 12e, third expansion valve 12f, cooler 12g, and low-pressure side indoor heat exchanger 12h.

[0007] This refrigerant cycle generates low-temperature cold air in the cooler 12g and the low-pressure side indoor heat exchanger 12h. The generated cold air is then delivered to the vehicle interior, battery B, and electronic component module P, thereby cooling the vehicle interior, battery B, and electronic component module P.

[0008] Furthermore, in heat pump mode, the first expansion valve 12c is opened, causing the refrigerant in the compressor 12a to circulate in the order of the high-pressure side indoor heat exchanger 12b, the first expansion valve 12c, and the outdoor heat exchanger 12d.

[0009] Additionally, high-temperature heat is generated in the high-pressure side indoor heat exchanger 12b through refrigerant circulation. The generated heat is supplied to the vehicle interior to heat it.

[0010] The refrigerant circulation line 12 also includes an electronic component waste heat cooler 12i. The electronic component waste heat cooler 12i is configured to allow the refrigerant in the refrigerant circulation line 12, which returns from the outdoor heat exchanger 12d to the compressor 12a, to exchange heat with the cooling water in the cooling water circulation line 22 of the water-cooled cooling device 20, which absorbs waste heat from the battery B and the electronic component module P.

[0011] Therefore, the waste heat from battery B and electronic component module P can be recovered into the refrigerant in refrigerant circulation line 12. This waste heat recovery can improve the heat pump mode efficiency of air conditioner 10.

[0012] Meanwhile, when the temperature of the outdoor heat exchanger 12d is reduced to a low temperature under specific external air conditions (e.g., high humidity conditions) and the air conditioner 10 enters heat pump mode, the problem is that icing may occur on the surface of the outdoor heat exchanger 12d.

[0013] Therefore, the air conditioner 10 also includes an anti-icing section 14 to prevent icing from occurring in the outdoor heat exchanger 12d.

[0014] The anti-icing section 14 includes a three-way flow control valve 14a, which allows the refrigerant to bypass the electronic component waste heat cooler 12i before being introduced into the outdoor heat exchanger 12d.

[0015] When icing occurs in the outdoor heat exchanger 12d, the anti-icing section 14 prevents icing of the outdoor heat exchanger by restricting the flow of refrigerant to the outdoor heat exchanger 12d before the refrigerant is introduced into the outdoor heat exchanger 12d.

[0016] However, when icing occurs in the outdoor heat exchanger 12d when entering heat pump mode, this conventional thermal management system requires altering the refrigerant flow in the refrigerant circulation line 12 via a three-way flow control valve 14a. Consequently, the refrigerant flow becomes unstable, and the efficiency of the heat pump mode decreases.

[0017] Specifically, while the three-way flow control valve 14a repeatedly operates to prevent icing of the outdoor heat exchanger 12d, the refrigerant flow in the refrigerant circulation line 12 changes frequently. Due to these frequent changes in refrigerant flow, the refrigerant flow in the circulation line 12 becomes unstable. The heat exchange rate in the high-pressure side indoor heat exchanger 12b fluctuates, and the temperature change of the air discharged into the vehicle interior intensifies. As a result, the heating performance inside the vehicle decreases.

[0018] Furthermore, conventional thermal management systems have a structure that restricts the flow of refrigerant to the outdoor heat exchanger 12d when icing occurs. Consequently, the heat exchange efficiency (evaporation efficiency) of the refrigerant is relatively reduced. Therefore, the amount of heat generated in the high-pressure side indoor heat exchanger 12b is also relatively reduced, resulting in poor heating performance inside the vehicle. Summary of the Invention

[0019] Technical issues

[0020] In view of the inherent problems in the related art, the object of the present invention is to provide a vehicle thermal management system that can respond to icing in the outdoor heat exchanger without restricting the flow of refrigerant to the outdoor heat exchanger when icing occurs.

[0021] Another object of the present invention is to provide a vehicle thermal management system that can prevent instability in refrigerant flow in the refrigerant circulation line due to the restriction of refrigerant flow to the outdoor heat exchanger when icing occurs in the outdoor heat exchanger.

[0022] Another object of the present invention is to provide a vehicle thermal management system that can prevent changes in the heat exchange rate in the high-pressure side indoor heat exchanger and changes in the temperature of the air discharged into the vehicle interior due to unstable refrigerant flow in the refrigerant circulation line, thereby improving the heating performance inside the vehicle.

[0023] Another object of the present invention is to provide a vehicle thermal management system that can prevent a decrease in the refrigerant heat exchange efficiency (evaporation efficiency) on the outdoor heat exchanger side due to restrictions on the flow of refrigerant to the outdoor heat exchanger.

[0024] Another object of the present invention is to provide a vehicle thermal management system that can prevent the reduction of heat generation in the high-pressure side indoor heat exchanger, thereby improving the heating performance inside the vehicle.

[0025] Technical solution

[0026] To achieve these objectives, a vehicle thermal management system is provided, comprising: a compressor disposed on a heat pump type refrigerant circulation line; a high-pressure side heat exchanger disposed on the heat pump type refrigerant circulation line; an outdoor heat exchanger disposed on the heat pump type refrigerant circulation line; a plurality of expansion valves disposed on the heat pump type refrigerant circulation line; a low-pressure side heat exchanger disposed on the heat pump type refrigerant circulation line; a first expansion valve disposed upstream of the outdoor heat exchanger; a second expansion valve disposed downstream of the outdoor heat exchanger; and a control unit configured to control the opening degree of the first expansion valve and the second expansion valve based on whether icing occurs in the outdoor heat exchanger under heat pump mode conditions.

[0027] In this system, the control unit can be configured to: if the control unit determines that icing has occurred in the outdoor heat exchanger, enter a dual expansion mode in which the refrigerant expands using both the first expansion valve and the second expansion valve; and if the control unit determines that no icing has occurred in the outdoor heat exchanger, enter a single expansion mode in which the refrigerant expands using only one of the first expansion valve and the second expansion valve.

[0028] In this system, the control unit can be configured to: fully open the second expansion valve on the downstream side of the outdoor heat exchanger in the single expansion mode, and control the opening degree of the first expansion valve on the upstream side of the outdoor heat exchanger to adjust the refrigerant flow rate on the outdoor heat exchanger side.

[0029] In this system, the control unit can be configured to control the opening degree of the first expansion valve and the second expansion valve in the dual expansion mode to regulate the refrigerant flow rate on the outdoor heat exchanger side.

[0030] In this system, the control unit can be configured to control the opening of the first expansion valve and the second expansion valve in the dual expansion mode to adjust the refrigerant flow rate on the outdoor heat exchanger side in the decreasing direction, thereby increasing the temperature of the outdoor heat exchanger to cope with the occurrence of icing.

[0031] In this system, the control unit can be configured to: in the dual expansion mode, maintain the opening degree of one of the first expansion valve and the second expansion valve constant, and vary the opening degree of the other of the first expansion valve and the second expansion valve.

[0032] In this system, the control unit can be configured to: maintain the opening of the first expansion valve constant in the dual expansion mode, and vary the opening of the second expansion valve.

[0033] In this system, the control unit can be configured to: in the dual expansion mode, periodically predict the probability of icing occurring in the outdoor heat exchanger according to pre-stored logic, and control the opening degree of the second expansion valve in a variable manner according to the predicted probability of icing.

[0034] In this system, the control unit can be configured to: in the dual expansion mode, periodically calculate the icing occurrence index of the outdoor heat exchanger at predetermined time intervals using the following pre-stored formula 2; the control unit can be configured to: predict a high probability of icing occurring in the outdoor heat exchanger if the calculated icing occurrence index is greater than the pre-stored reference index; and the control unit can be configured to: predict a low probability of icing occurring in the outdoor heat exchanger if the calculated icing occurrence index is less than the reference index.

[0035] [Formula 2]

[0036] Icing Index (I) = Outdoor Air Temperature (Tamb) - Outdoor Heat Exchanger Outlet Refrigerant Temperature (Tref)

[0037] Beneficial effects

[0038] According to the vehicle thermal management system of the present invention, when icing occurs in the outdoor heat exchanger under heat pump mode, the temperature of the outdoor heat exchanger is regulated by controlling the opening degree of the third expansion valve on the downstream side of the outdoor heat exchanger. Therefore, when icing occurs in the outdoor heat exchanger, the flow of refrigerant to the outdoor heat exchanger can be controlled without restricting the flow of refrigerant to the outdoor heat exchanger.

[0039] In addition, since it can handle icing in the outdoor heat exchanger without restricting the flow of refrigerant to the outdoor heat exchanger, it can prevent unstable flow of refrigerant in the refrigerant circulation line caused by the restriction of the flow of refrigerant to the outdoor heat exchanger when icing occurs in the outdoor heat exchanger.

[0040] Furthermore, since it can prevent instability in the flow of refrigerant in the refrigerant circulation line due to the restriction of refrigerant flow to the outdoor heat exchanger, it can prevent fluctuations in the heat exchange rate in the high-pressure side indoor heat exchanger caused by the instability in the flow of refrigerant in the refrigerant circulation line and the resulting change in the temperature of the air discharged into the vehicle interior, thereby improving the heating performance inside the vehicle.

[0041] In addition, when icing occurs in the outdoor heat exchanger, the system can handle the icing without restricting the flow of refrigerant to the outdoor heat exchanger. Therefore, it can prevent a decrease in the refrigerant heat exchange efficiency (evaporation efficiency) on the outdoor heat exchanger side due to the restriction of refrigerant flow to the outdoor heat exchanger.

[0042] Furthermore, since it can prevent the reduction of refrigerant heat exchange efficiency (evaporation efficiency) on the outdoor heat exchanger side due to the restriction of refrigerant flow to the outdoor heat exchanger, it can prevent the reduction of heat generation in the high-pressure side indoor heat exchanger, thereby improving the heating performance inside the vehicle. Attached Figure Description

[0043] Figure 1 This is a diagram illustrating a conventional vehicle thermal management system.

[0044] Figure 2 This is a diagram illustrating a vehicle thermal management system according to a first embodiment of the present invention.

[0045] Figure 3 This is a diagram illustrating an operational example of a vehicle thermal management system according to a first embodiment of the present invention, showing the control of the vehicle thermal management system when no icing occurs in the outdoor heat exchanger in heat pump mode.

[0046] Figure 4 This is a diagram illustrating an operational example of a vehicle thermal management system according to a first embodiment of the present invention, showing the control of the vehicle thermal management system when icing occurs in the outdoor heat exchanger in heat pump mode.

[0047] Figure 5 This is a flowchart illustrating an operational example of a vehicle thermal management system according to a first embodiment of the present invention, and an operational example illustrating whether icing occurs in the outdoor heat exchanger under heat pump mode conditions.

[0048] Figure 6 This is a diagram illustrating a vehicle thermal management system according to a second embodiment of the present invention.

[0049] Figure 7 This is a flowchart illustrating an operational example of a vehicle thermal management system according to a second embodiment of the present invention, and an operational example illustrating whether icing occurs in the outdoor heat exchanger under heat pump mode conditions. Detailed Implementation

[0050] A preferred embodiment of the vehicle thermal management system according to the present invention will now be described in detail with reference to the accompanying drawings.

[0051] [First Implementation Method]

[0052] Before describing the features of the vehicle thermal management system according to the present invention, reference will be made to... Figure 2 Briefly describe the general configuration of the vehicle's thermal management system.

[0053] The vehicle thermal management system includes an air conditioner 100 and a water-cooled cooling device 200. The air conditioner cools and heats the vehicle interior, and the water-cooled cooling device cools the battery B and the electronic component module P.

[0054] Air conditioner 100 is a heat pump type and includes refrigerant circulation line 110.

[0055] The refrigerant circulation line 110 includes a compressor 112, a high-pressure side indoor heat exchanger 114, a first expansion valve 116, an outdoor heat exchanger 118, a second expansion valve 120, a third expansion valve 122 connected in parallel with the second expansion valve 120, a cooler 124 arranged downstream of the second expansion valve 120, and a low-pressure side indoor heat exchanger 126 located downstream of the third expansion valve 122.

[0056] The first expansion valve 116 and the second expansion valve 120 are electromagnetic type (EXV), while the third expansion valve 122 is thermostatic type (TXV) with opening and closing functions.

[0057] In the refrigerant circulation line 110, in air conditioning mode, the first expansion valve 116 is opened, so that the refrigerant in the compressor 112 can circulate in the following order: high-pressure side indoor heat exchanger 114, outdoor heat exchanger 118, second expansion valve 120, third expansion valve 122, cooler 124, and low-pressure side indoor heat exchanger 126.

[0058] This refrigerant cycle generates low-temperature cold air in the cooler 124 and the low-pressure side indoor heat exchanger 126. The generated cold air is then delivered to the vehicle interior, battery B, and electronic component module P. Therefore, the vehicle interior, battery B, and electronic component module P are cooled.

[0059] In addition, in heat pump mode, the first expansion valve 116 is opened, so that the refrigerant in the compressor 112 circulates in the order of the high-pressure side indoor heat exchanger 114, the first expansion valve 116 and the outdoor heat exchanger 118.

[0060] Furthermore, high-temperature heat is generated in the high-pressure side indoor heat exchanger 114 through refrigerant circulation. The generated heat is supplied to the vehicle interior to heat the vehicle interior.

[0061] Meanwhile, in heat pump mode, cooler 124 is also used to allow the refrigerant in refrigerant circulation line 110 returning from outdoor heat exchanger 118 to compressor 112 to exchange heat with the cooling water on the cooling water circulation line 210 side of water-cooled cooling device 200, which has absorbed the waste heat of battery B and electronic component module P.

[0062] Therefore, in heat pump mode, waste heat from battery B and electronic component module P can be recovered into the refrigerant in refrigerant circulation line 110.

[0063] Furthermore, the second expansion valve 120 located on the upstream side of the cooler 124 is configured to vary the amount of refrigerant pressure reduction / expansion introduced into the cooler 124, even in heat pump mode.

[0064] Therefore, in heat pump mode, the amount of heat absorbed by the upstream cooler 124 and the outdoor heat exchanger 118 can be varied.

[0065] In particular, the temperature of the outdoor heat exchanger 118 can be regulated by allowing variable adjustment of the heat absorbed by the upstream outdoor heat exchanger 118.

[0066] Next, we will refer to Figures 2 to 5 The features of the vehicle thermal management system according to the present invention are described in detail.

[0067] First refer to Figure 2 The vehicle thermal management system according to the present invention includes an icing occurrence determination unit 300, which determines whether icing occurs in the outdoor heat exchanger 118 when entering heat pump mode.

[0068] The icing occurrence determination unit 300 includes an outdoor air temperature sensor 310 and a control unit 320. The outdoor air temperature sensor detects the temperature outside the vehicle interior, and the control unit determines whether icing has occurred in the outdoor heat exchanger 118 based on the outdoor air temperature data input from the outdoor air temperature sensor 310.

[0069] An outdoor air temperature sensor 310 is installed on the exterior of the vehicle interior and is configured to detect the outdoor air temperature and input the detected outdoor air temperature data to the control unit 320.

[0070] The control unit 320 is equipped with a microprocessor. When outdoor air temperature data is input from the outdoor air temperature sensor 310 in heat pump mode, the control unit 320 determines whether the input outdoor air temperature falls within the temperature range where icing occurs in the outdoor heat exchanger 118, thereby determining whether icing has occurred in the outdoor heat exchanger 118.

[0071] In other words, as shown in Formula 1 below, it determines whether the outdoor air temperature falls within a range that exceeds the first set temperature but is smaller than the second set temperature which is higher than the first set temperature.

[0072] [Formula 1]

[0073] First set temperature < Outdoor air temperature < Second set temperature

[0074] As a result, if the outdoor air temperature does not fall within the range of exceeding the first set temperature and being smaller than the second set temperature, the control unit 320 determines that no icing has occurred in the outdoor heat exchanger 118.

[0075] As a result, if the outdoor air temperature falls within a range that exceeds the first set temperature but is less than the second set temperature, the control unit 320 determines that icing has occurred in the outdoor heat exchanger 118.

[0076] In this regard, it is preferable that the first set temperature, which serves as the standard for determining whether icing occurs in the outdoor heat exchanger 118, is set to -5 degrees Celsius, and the second set temperature is set to 5 degrees Celsius.

[0077] This is because it was found that under heat pump mode conditions, icing occurs in the outdoor heat exchanger 118 when the outdoor air temperature is between -5 degrees Celsius and 5 degrees Celsius.

[0078] Refer again Figure 2 After determining whether icing has occurred in the outdoor heat exchanger 118, the control unit 320 controls the first expansion valve 116 and the second expansion valve 120 on the upstream and downstream sides of the outdoor heat exchanger 118 according to the determination result, so as to prevent icing from occurring in the outdoor heat exchanger 118.

[0079] To explain in more detail, if it is determined that no icing has occurred in the outdoor heat exchanger 118, the control unit 320 enters a single expansion mode 320a. The control unit 320 is configured to control only one of the first expansion valve 116 and the second expansion valve 120 in the single expansion mode 320a.

[0080] Specifically, the second expansion valve 120 is fully opened and its opening is controlled only for the first expansion valve 116 to regulate the pressure reduction / expansion of the refrigerant introduced into the outdoor heat exchanger 118.

[0081] Therefore, as Figure 3As shown in the pH diagram, a high refrigerant evaporation rate (D-D') can be maintained in the outdoor heat exchanger 118. With this high refrigerant evaporation rate, the outdoor heat exchanger 118 enables the control of the heat output of the high-pressure side indoor heat exchanger 114 while maintaining a temperature lower than the outdoor air temperature.

[0082] When it is determined that icing has occurred in the outdoor heat exchanger 118, the control unit 320 enters... Figure 2 The dual expansion mode 320b is shown. In the dual expansion mode 320b, the control unit 320 is configured to control both the first expansion valve 116 and the second expansion valve 120.

[0083] In particular, such as Figure 4 As shown in the pH diagram, by varying the opening of the second expansion valve 120, the refrigerant on the downstream side of the outdoor heat exchanger 118 is again depressurized and expanded (D'-D”). During the process of depressurization and expansion of the refrigerant on the downstream side, the flow rate of the refrigerant on the outdoor heat exchanger 118 side decreases.

[0084] Therefore, the refrigerant evaporation rate (D-D') in the outdoor heat exchanger 118 is reduced, and due to this lower refrigerant evaporation rate, the outdoor heat exchanger 118 can maintain a temperature higher than the outdoor temperature.

[0085] Therefore, icing in the outdoor heat exchanger 118 can be prevented. In particular, since the outdoor heat exchanger 118 is maintained at a temperature higher than the outdoor air temperature, icing in the outdoor heat exchanger 118 is fundamentally prevented. Even if icing does occur in the outdoor heat exchanger 118, the icing can be quickly removed.

[0086] Refer again Figure 2 When the dual expansion mode 320b is entered, the control unit 320 controls the opening of the second expansion valve 120 to prevent icing from occurring in the outdoor heat exchanger 118. Thereafter, the control unit 320 periodically predicts the probability of icing occurring in the outdoor heat exchanger 118 according to preset logic, and periodically controls the opening of at least one of the first expansion valve 116 and the second expansion valve 120 according to the predicted probability of icing occurring in the outdoor heat exchanger.

[0087] In other words, under the dual expansion mode 320b, the control unit 320 periodically calculates the icing occurrence index I in the outdoor heat exchanger 118 at predetermined time intervals using the following formula 2. For example, the icing occurrence index I is calculated at 30-second intervals.

[0088] [Formula 2]

[0089] Icing Index (I) = Outdoor Air Temperature (Tamb) - Outdoor Heat Exchanger Outlet Refrigerant Temperature (Tref)

[0090] When the calculation of the icing occurrence index I is completed, the control unit 320 compares the calculated icing occurrence index I with the pre-stored reference index Tset to predict the probability of icing occurring in the outdoor heat exchanger 118, and controls the opening degree of the second expansion valve 120 in a variable manner according to the predicted probability of icing.

[0091] Specifically, the control unit 320 compares the icing occurrence index I with the reference index Tset, predicts the probability of icing occurring in the outdoor heat exchanger 118 based on the comparison result, and increases or decreases the opening of the second expansion valve 120 by a preset value based on the predicted probability of icing.

[0092] In other words, for example, if it is confirmed that the calculated icing occurrence index I is greater than the reference index Tset, the control unit 320 determines that the outdoor heat exchanger 118 has a high probability of icing occurring in the outdoor heat exchanger 118. Based on this determination, the control unit 320 reduces the opening of the second expansion valve 120 by a predetermined value.

[0093] Therefore, the flow rate of the refrigerant in the outdoor heat exchanger 118 is reduced by a predetermined amount, thereby reducing the evaporation rate of the refrigerant in the outdoor heat exchanger, so that the temperature of the outdoor heat exchanger can be maintained at a higher level.

[0094] As a result, by actively addressing the high probability of icing in the outdoor heat exchanger 118, icing in the outdoor heat exchanger 118 can be fundamentally prevented.

[0095] Conversely, if the calculated icing occurrence index I is confirmed to be less than the reference index Tset, the control unit 320 determines that the probability of icing occurring in the outdoor heat exchanger 118 is low. Based on this determination, the control unit 320 increases the opening of the second expansion valve 120 by a predetermined value.

[0096] Therefore, the refrigerant flow rate in the outdoor heat exchanger 118 is increased by a predetermined amount, thereby increasing the refrigerant evaporation rate in the outdoor heat exchanger 118, so that the temperature of the outdoor heat exchanger 118 can be maintained at a lower level.

[0097] As a result, the low probability of icing occurring in the outdoor heat exchanger 118 can be proactively addressed.

[0098] At the same time, when the calculated icing occurrence index I is equal to the reference index Tset, the control unit 320 controls the opening of the second expansion valve 120 to be maintained in the current state.

[0099] Refer again Figure 2In the dual expansion mode 320b, when the opening degree of the second expansion valve 120 is controlled in a variable manner, the control unit 320 fixes the opening degree of the first expansion valve 116.

[0100] Specifically, when the opening of the second expansion valve 120 is controlled according to the probability of icing in the outdoor heat exchanger 118, the control unit 320 controls the opening of the first expansion valve 116 to the opening that is available before entering the dual expansion mode 320b or a preset opening.

[0101] Therefore, in the dual expansion mode 320b, the opening of the first expansion valve 116 is fixed, the amount of refrigerant pressure reduction / expansion introduced into the outdoor heat exchanger 118 is kept constant, and the heat absorption temperature of the outdoor heat exchanger 118 is controlled only by adjusting the opening of the second expansion valve 120, while the refrigerant flow rate on the outdoor heat exchanger 118 side is controlled.

[0102] Meanwhile, in the dual expansion mode 320b, the opening degree of the second expansion valve 120 can be fixed at a constant value, depending on the situation, while the opening degree of the first expansion valve 116 can be varied.

[0103] Specifically, the opening degree of the second expansion valve 120 can be fixed at a preset value, and the opening degree of the first expansion valve 116 can be controlled in a variable manner according to the probability of icing occurring in the outdoor heat exchanger 118.

[0104] Therefore, the refrigerant flow rate in the outdoor heat exchanger 118 and the heat absorption temperature in the outdoor heat exchanger 118 can be controlled simply by adjusting the opening of the first expansion valve 116.

[0105] Refer again Figure 2 In the dual expansion mode 320b, if the outdoor air temperature input by the outdoor air temperature sensor 310 does not fall within the icing temperature range of the outdoor heat exchanger 118, that is, if the outdoor air temperature is a first set temperature (-5 degrees Celsius) or lower, or a second set temperature (5 degrees Celsius) or higher, the control unit 320 determines that there is no possibility of icing occurring in the outdoor heat exchanger 118.

[0106] Based on this determination, the control unit 320 enters a single expansion mode 320a while being released from the dual expansion mode 320b. The control unit 320, which has entered the single expansion mode 320a, fully opens the second expansion valve 120 and controls only the first expansion valve 116 to regulate the amount of pressure reduction / expansion of the refrigerant introduced into the outdoor heat exchanger 118.

[0107] Meanwhile, in single expansion mode 320a, the control unit 320 periodically predicts the probability of icing occurring in the outdoor heat exchanger 118 according to preset logic.

[0108] Specifically, as described above, the control unit 320 periodically calculates the icing occurrence index I of the outdoor heat exchanger 118 at predetermined time intervals using Formula 2, and compares the calculated icing occurrence index I with a pre-stored reference index Tset to predict the probability of icing occurring in the outdoor heat exchanger 118.

[0109] As a result of predicting the probability of icing occurring in the outdoor heat exchanger 118, if it is determined that the probability of icing occurring in the outdoor heat exchanger 118 is high, the control unit 320 controls the first expansion valve 116 and the second expansion valve 120 when switching from the single expansion mode 320a to the dual expansion mode 320b.

[0110] Specifically, the control unit 320 controls the first expansion valve 116 and the second expansion valve 120 to cause the refrigerant to expand twice in the outdoor heat exchanger 118. By causing the refrigerant to expand twice, the control unit 320 regulates the flow rate of the refrigerant in the outdoor heat exchanger 118. By regulating the flow rate of the refrigerant in the outdoor heat exchanger 118, the control unit 320 controls the temperature of the outdoor heat exchanger and fundamentally prevents surface icing.

[0111] Next, we will refer to Figure 2 and Figure 5 A detailed description of an operational example of the vehicle thermal management system according to the present invention, having this configuration.

[0112] First refer to Figure 5 In heat pump mode (S101), it is determined whether the outdoor air temperature falls within the range of exceeding the first set temperature (-5 degrees Celsius) and being less than the second set temperature (5 degrees Celsius) (S103).

[0113] As a result, if the outdoor air temperature does not fall within the range of exceeding the first set temperature (-5 degrees Celsius) and being less than the second set temperature (5 degrees Celsius) (S103-1), the control unit 320 determines that no icing has occurred in the outdoor heat exchanger 118. Based on this determination, the control unit 320 enters the single expansion mode 320a (S105).

[0114] like Figure 2 and Figure 5 As shown, the control unit 320, which has entered the single expansion mode 320a, fully opens the second expansion valve 120 and controls only the first expansion valve 116 to vary the amount of pressure reduction / expansion of the refrigerant introduced into the outdoor heat exchanger 118 (S107).

[0115] Simultaneously, as a result determined in step S103, if the outdoor air temperature falls within the range exceeding the first set temperature (-5 degrees Celsius) and below the second set temperature (5 degrees Celsius) (S103-2), the control unit 320 determines that icing has occurred in the outdoor heat exchanger 118. Based on this determination, the control unit 320 enters the dual expansion mode 320b (S109).

[0116] The control unit 320, which has entered the dual expansion mode 320b, controls the opening degree of the first expansion valve 116 and the second expansion valve 120 (S111).

[0117] Specifically, by varying the opening of the second expansion valve 120, the control unit 320 again depressurizes and expands the refrigerant on the downstream side of the outdoor heat exchanger 118, thereby reducing the refrigerant flow rate in the outdoor heat exchanger 118 and lowering the refrigerant evaporation rate in the outdoor heat exchanger 118.

[0118] Then, the temperature of the outdoor heat exchanger 118 is increased to prevent icing from occurring on the surface and to remove any icing that occurs.

[0119] Meanwhile, in the dual expansion mode 320b, the control unit 320 periodically calculates the icing index I (S113) of the outdoor heat exchanger 118 using Formula 2 at predetermined time intervals.

[0120] When the calculation of the icing occurrence index I is completed, the control unit 320 periodically determines whether the calculated icing occurrence index I is greater than the pre-stored reference index Tset (S115).

[0121] As a result, if the icing occurrence index I is greater than the reference index Tset, the control unit 320 determines that the probability of icing occurring in the outdoor heat exchanger 118 is high, and thereby reduces the opening of the second expansion valve 120 by a preset value (S117).

[0122] Then, the refrigerant flow rate in the outdoor heat exchanger 118 decreases, and the refrigerant evaporation rate in the outdoor heat exchanger 118 decreases. The temperature of the outdoor heat exchanger 118 increases due to the reduced evaporation rate. This makes it possible to cope with the probability of icing occurring in the outdoor heat exchanger 118.

[0123] Meanwhile, as a result of the determination in step S115, if the icing occurrence index I is not greater than the reference index Tset (S115-1), the control unit 320 determines again whether the icing occurrence index I is less than the reference index Tset (S119).

[0124] As a result, if the icing occurrence index I is less than the reference index Tset, the control unit 320 determines that the probability of icing occurring in the outdoor heat exchanger 118 is low, and thereby increases the opening of the second expansion valve 120 by a preset value (S121).

[0125] Then, the refrigerant flow rate in the outdoor heat exchanger 118 increases, and the refrigerant evaporation rate in the outdoor heat exchanger 118 increases. The temperature of the outdoor heat exchanger 118 decreases due to the increased evaporation rate. This makes it possible to cope with the probability of icing occurring in the outdoor heat exchanger 118.

[0126] Meanwhile, as a result of the determination in step S119, if the icing occurrence index I is not less than the reference index Tset (S119-1), the control unit 320 determines again whether the icing occurrence index I is equal to the reference index Tset (S123).

[0127] As a result, if the icing occurrence index I is equal to the reference index Tset, the control unit 320 will maintain the opening of the second expansion valve 120 in the current state (S125).

[0128] According to the vehicle thermal management system of the present invention, when icing occurs in the outdoor heat exchanger 118 under heat pump mode, the temperature of the outdoor heat exchanger 118 is regulated by controlling the opening degree of the second expansion valve 120 on the downstream side of the outdoor heat exchanger 118. Therefore, when icing occurs in the outdoor heat exchanger 118, the flow of refrigerant to the outdoor heat exchanger 118 can be controlled without restricting the flow of refrigerant to the outdoor heat exchanger 118.

[0129] In addition, since it can cope with icing in the outdoor heat exchanger 118 without restricting the flow of refrigerant to the outdoor heat exchanger 118, it can prevent unstable flow of refrigerant in the refrigerant circulation line due to restriction of the flow of refrigerant to the outdoor heat exchanger 118 when icing occurs in the outdoor heat exchanger 118.

[0130] Furthermore, since the instability of refrigerant flow in the refrigerant circulation line 110 due to the restriction of refrigerant flow to the outdoor heat exchanger 118 can be prevented, the fluctuation of heat exchange rate in the high-pressure side indoor heat exchanger 114 due to the instability of refrigerant flow in the refrigerant circulation line 110 and the resulting change in the temperature of the air discharged into the vehicle interior can be prevented, thereby improving the heating performance inside the vehicle.

[0131] Furthermore, since it can handle the occurrence of icing in the outdoor heat exchanger 118 without restricting the flow of refrigerant to the outdoor heat exchanger 118, it can prevent the reduction of refrigerant heat exchange efficiency (evaporation efficiency) on the outdoor heat exchanger 118 side due to the restriction of refrigerant flow to the outdoor heat exchanger 118.

[0132] In addition, since the reduction in refrigerant heat exchange efficiency (evaporation efficiency) on the outdoor heat exchanger 118 side due to the restriction of refrigerant flow to the outdoor heat exchanger 118 can be prevented, the reduction in heat generation in the high-pressure side indoor heat exchanger 114 can be prevented, thereby improving the heating performance inside the vehicle.

[0133] [Second Implementation]

[0134] Figure 6 This is a diagram illustrating a vehicle thermal management system according to a second embodiment of the present invention.

[0135] The vehicle thermal management system according to the second embodiment has the same main configuration as the vehicle thermal management system according to the first embodiment described above.

[0136] In particular, the vehicle thermal management system according to the second embodiment has the same structure as the vehicle thermal management system according to the first embodiment, wherein when icing occurs in the outdoor heat exchanger 118 under heat pump mode, the temperature of the outdoor heat exchanger is adjusted by controlling the opening of the second expansion valve 120 on the downstream side of the outdoor heat exchanger 118, thereby preventing icing in the outdoor heat exchanger 118 without restricting the flow of refrigerant to the outdoor heat exchanger 118.

[0137] However, the vehicle thermal management system according to the second embodiment differs from the vehicle thermal management system according to the first embodiment in that the icing occurrence determination unit 300 is used to determine whether icing occurs in the outdoor heat exchanger 118.

[0138] Specifically, the icing occurrence determination unit 300 of the first embodiment is configured to determine whether icing occurs in the outdoor heat exchanger 118 based on outdoor air temperature data. However, the icing occurrence determination unit 300 of the second embodiment is configured to determine whether icing occurs in the outdoor heat exchanger 118 based on two types of data, namely outdoor air temperature and outdoor air humidity.

[0139] To provide a more detailed explanation, the icing occurrence determination unit 300 of the second embodiment also includes an outdoor air humidity sensor 330.

[0140] An outdoor air humidity sensor 330 is installed outside the vehicle interior and is configured to detect the relative humidity of outdoor air (hereinafter referred to as "outdoor air humidity") and input the detected outdoor air humidity data to the control unit 320.

[0141] Meanwhile, when outdoor air temperature data and outdoor air humidity data are input from outdoor air temperature sensor 310 and outdoor air humidity sensor 330 respectively in heat pump mode, control unit 320 determines whether outdoor air temperature and outdoor air humidity meet all preset conditions respectively, and then determines whether icing occurs in outdoor heat exchanger 118 based on whether all conditions are met.

[0142] In other words, when outdoor air temperature data and outdoor air humidity data are input from outdoor air temperature sensor 310 and outdoor air humidity sensor 330 respectively, the control unit 320 determines whether the input outdoor air temperature meets the condition in Formula 1 above that the outdoor air temperature falls within the range of exceeding the first set temperature and being less than the second set temperature (hereinafter referred to as the "first condition").

[0143] Then, as shown in Formula 3 below, the control unit 320 determines whether the input outdoor air humidity meets the condition that the outdoor air humidity is equal to or greater than the preset reference humidity (hereinafter referred to as the "second condition").

[0144] [Formula 3]

[0145] Outdoor air humidity ≥ reference humidity

[0146] As a result, if either the first condition or the second condition is not met, that is, if neither the first condition (where the outdoor air temperature falls within the range of a first set temperature and a second set temperature) nor the second condition (where the outdoor air humidity is equal to or greater than a preset reference humidity) is met, then the control unit 320 determines that no icing has occurred in the outdoor heat exchanger 118.

[0147] If all of the first and second conditions are met, that is, if the outdoor air temperature falls within the range of the first condition which exceeds the first set temperature and is less than the second set temperature, and the outdoor air humidity is equal to or greater than the preset reference humidity, the control unit 320 determines that icing has occurred in the outdoor heat exchanger 118.

[0148] Based on the determined results, as in the first embodiment, the control unit 320 controls the first expansion valve 116 and the second expansion valve 120 when entering the single expansion mode 320a or the dual expansion mode 320b.

[0149] In this regard, the reference humidity, which serves as a standard for determining whether icing has occurred in the outdoor heat exchanger 118, is preferably set to 75% relative humidity.

[0150] This is because, under heat pump mode, when the outdoor air humidity is equal to or greater than 75% relative humidity, icing occurs in the outdoor heat exchanger 118.

[0151] Next, we will refer to Figure 6 and Figure 7 A detailed description of an operational example of the vehicle thermal management system according to the second embodiment, having this configuration.

[0152] First refer to Figure 7 In heat pump mode (S201), control unit 320 determines whether all of the following conditions are met: the outdoor air temperature falls within the range of the first set temperature (-5 degrees Celsius) and the second set temperature (5 degrees Celsius) and the outdoor air humidity is equal to or greater than the reference humidity (75%) (S203).

[0153] As a result, if neither the condition that the outdoor air temperature falls within the range of the first set temperature (-5 degrees Celsius) and the condition that the outdoor air humidity is equal to or greater than the reference humidity (75%) is met (S203-1), the control unit 320 determines that no icing has occurred in the outdoor heat exchanger 118, and enters the single expansion mode 320a based on this determination (S205).

[0154] The operational example after entering the single expansion mode 320a is the same as the operational example of the first embodiment described above. Therefore, its description will be omitted.

[0155] On the other hand, as a result of the determination in step S203, if both the condition that the outdoor air temperature falls within the range of exceeding the first set temperature (-5 degrees Celsius) and being less than the second set temperature (5 degrees Celsius) and the condition that the outdoor air humidity is equal to or greater than the reference humidity (75%) are met (S203-2), then the control unit 320 determines that icing has occurred in the outdoor heat exchanger 118, and enters the dual expansion mode 320b based on this determination (S209).

[0156] The operation example after entering the dual expansion mode 320b is the same as the operation example of the first embodiment described above. Therefore, its description will be omitted.

[0157] According to the vehicle thermal management system of the second embodiment with this configuration, the control unit 320 is configured to determine whether icing has occurred in the outdoor heat exchanger 118 based on outdoor air temperature data and outdoor air humidity data, which makes it possible to accurately determine whether icing has occurred in the outdoor heat exchanger 118.

[0158] Furthermore, since it is possible to accurately determine whether icing occurs in the outdoor heat exchanger 118, the timing of entering the dual expansion mode 320b due to icing in the outdoor heat exchanger 118 can be precisely controlled.

[0159] In particular, because the timing of entering the dual expansion mode 320b can be precisely controlled, unstable refrigerant flow in the refrigerant circulation line 110 caused by entering the dual expansion mode 320b can be minimized. This allows for improved performance of the heat pump mode.

[0160] Although preferred embodiments of the invention have been described above, the invention is not limited to these embodiments. Various modifications and changes can be made without departing from the scope and spirit of the invention as defined in the claims.

Claims

1. A vehicle thermal management system, the vehicle thermal management system comprising: The compressor is arranged on a heat pump type refrigerant circulation line; A high-pressure side heat exchanger is arranged on the heat pump type refrigerant circulation line; An outdoor heat exchanger is arranged on the heat pump type refrigerant circulation line; Multiple expansion valves are arranged on the heat pump type refrigerant circulation line; A low-pressure side heat exchanger is arranged on the heat pump type refrigerant circulation line; A first expansion valve is disposed on the upstream side of the outdoor heat exchanger; A second expansion valve is arranged on the downstream side of the outdoor heat exchanger; as well as The control unit is configured to control the opening degree of the first expansion valve and the second expansion valve based on whether icing occurs in the outdoor heat exchanger under heat pump mode conditions. The control unit is configured to: if the control unit determines that icing has occurred in the outdoor heat exchanger, enter a dual expansion mode in which the refrigerant expands using both the first expansion valve and the second expansion valve; and if the control unit determines that no icing has occurred in the outdoor heat exchanger, enter a single expansion mode in which the refrigerant expands using only one of the first expansion valve and the second expansion valve. The control unit is configured to: in the single expansion mode, fully open the second expansion valve on the downstream side of the outdoor heat exchanger, and control the opening degree of the first expansion valve on the upstream side of the outdoor heat exchanger to adjust the refrigerant flow rate on the outdoor heat exchanger side. The control unit is configured to control the opening of the first expansion valve and the second expansion valve in the dual expansion mode to adjust the refrigerant flow rate on the outdoor heat exchanger side in the decreasing direction, thereby increasing the temperature of the outdoor heat exchanger to cope with the occurrence of icing.

2. The vehicle thermal management system according to claim 1, wherein, The control unit is configured to: determine that icing has occurred in the outdoor heat exchanger when the outdoor air temperature falls within a range exceeding a first set temperature but below a second set temperature that is higher than the first set temperature; The control unit is configured to determine that no icing has occurred in the outdoor heat exchanger when the outdoor air temperature does not fall within the range of exceeding the first set temperature and being less than the second set temperature.

3. The vehicle thermal management system according to claim 1, wherein, The control unit is configured to determine that icing has occurred in the outdoor heat exchanger when both a first condition (outdoor air temperature falling within a range exceeding a first set temperature and below a second set temperature) and a second condition (outdoor air humidity equal to or greater than a preset reference humidity) are met, and... If either the first condition or the second condition is not met, the control unit determines that no icing has occurred in the outdoor heat exchanger.

4. A vehicle thermal management system, the vehicle thermal management system comprising: The compressor is arranged on a heat pump type refrigerant circulation line; A high-pressure side heat exchanger is arranged on the heat pump type refrigerant circulation line; An outdoor heat exchanger is arranged on the heat pump type refrigerant circulation line; Multiple expansion valves are arranged on the heat pump type refrigerant circulation line; A low-pressure side heat exchanger is arranged on the heat pump type refrigerant circulation line; A first expansion valve is disposed on the upstream side of the outdoor heat exchanger; A second expansion valve is arranged on the downstream side of the outdoor heat exchanger; as well as The control unit is configured to control the opening degree of the first expansion valve and the second expansion valve based on whether icing occurs in the outdoor heat exchanger under heat pump mode conditions. The control unit is configured to: if the control unit determines that icing has occurred in the outdoor heat exchanger, enter a dual expansion mode in which the refrigerant expands using both the first expansion valve and the second expansion valve; and if the control unit determines that no icing has occurred in the outdoor heat exchanger, enter a single expansion mode in which the refrigerant expands using only one of the first expansion valve and the second expansion valve. The control unit is configured to: in the dual expansion mode, maintain a constant opening degree of one of the first expansion valve and the second expansion valve, and variablely control the opening degree of the other of the first expansion valve and the second expansion valve. The control unit is configured to: maintain the opening degree of the first expansion valve constant in the dual expansion mode, and vary the opening degree of the second expansion valve.

5. The vehicle thermal management system according to claim 4, wherein, The control unit is configured to: in the dual expansion mode, periodically predict the probability of icing occurring in the outdoor heat exchanger according to pre-stored logic, and control the opening degree of the second expansion valve in a variable manner according to the predicted probability of icing.

6. The vehicle thermal management system according to claim 5, wherein, The control unit is configured to: in the dual expansion mode, periodically calculate the icing index of the outdoor heat exchanger at predetermined time intervals using pre-stored formula 2: Icing Index = Outdoor Air Temperature - Outdoor Heat Exchanger Outlet Refrigerant Temperature. The control unit is configured to predict a high probability of icing occurring in the outdoor heat exchanger if the calculated icing occurrence index is greater than a pre-stored reference index. The control unit is configured to predict a low probability of icing occurring in the outdoor heat exchanger if the calculated icing occurrence index is smaller than the reference index.

7. The vehicle thermal management system according to claim 6, wherein, The control unit is configured to reduce the opening of the second expansion valve by a preset value when it is determined that the probability of icing occurring in the outdoor heat exchanger is high, so as to reduce the refrigerant flow rate in the outdoor heat exchanger by a preset value.

8. The vehicle thermal management system according to claim 7, wherein, The control unit is configured to increase the opening of the second expansion valve by a preset value when it is determined that the probability of icing occurring in the outdoor heat exchanger is low, thereby increasing the refrigerant flow rate in the outdoor heat exchanger by a preset value.

9. The vehicle thermal management system according to claim 8, wherein, The control unit is configured to maintain the opening of the second expansion valve in its current state when the icing occurrence index equals the reference index.

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