A battery cooling system and method

Abstract

The present invention provides a battery cooling system and method, comprising: a first expansion valve, a direct cooling plate heat exchanger, a controller, a compressor, and a battery direct cooling plate disposed outside the battery; the direct cooling plate heat exchanger includes a first heat exchange circuit and a second heat exchange circuit; the inlet of the first heat exchange circuit is connected to the outlet of the compressor, the outlet of the first heat exchange circuit is connected to the inlet of the first expansion valve, and the outlet of the first expansion valve is connected to the inlet of the battery direct cooling plate; the inlet of the second heat exchange circuit is connected to the outlet of the battery direct cooling plate, and the outlet of the second heat exchange circuit is connected to the inlet of the compressor; the controller is used to adjust the heat exchange amount of the direct cooling plate heat exchanger by controlling the opening degree of the first expansion valve; in the embodiments of the present invention, by adjusting the first expansion valve, on the basis of avoiding the excessive temperature at the outlet of the battery direct cooling plate, the ideal superheat degree at the outlet of the direct cooling plate heat exchanger can be ensured, and the refrigerant at the outlet of the battery direct cooling plate is in the two-phase state interval with an ideal dryness degree.

Description

Technical Field

[0001] The present invention relates to the technical field of automobiles, and particularly relates to a battery cooling system and method. Background Art

[0002] With the popularization of private cars and the continuous development of battery technology, the market share of electric vehicles is increasing continuously.

[0003] For existing electric vehicles, in order to cool the battery, a direct cooling plate can be arranged outside the battery for external cooling. First, the state of the refrigerant at the outlet of the direct cooling plate can be determined by the collected values of the pressure and temperature at the outlet of the direct cooling plate. Then, by adjusting the regulating valve, the state of the refrigerant can be changed so that the state of the refrigerant in the direct cooling plate meets the target conditions.

[0004] However, in the current solution, the refrigerant at the outlet of the direct cooling plate is prone to an overheated state. When this overheated state is detected, the two-phase state performance of the refrigerant in the direct cooling plate is poor, and there is already a large temperature difference between the refrigerant at the outlet of the direct cooling plate and the refrigerant at other positions of the direct cooling plate, thus affecting the temperature consistency of the battery. Summary of the Invention

[0005] In view of this, the present invention aims to provide a battery cooling system and method to solve the problem in the prior art that the refrigerant at the outlet of the direct cooling plate is prone to an overheated state during the battery cooling process. When this overheated state is detected, there is already a large temperature difference between the refrigerant at the outlet of the direct cooling plate and the refrigerant at other positions of the direct cooling plate, thus affecting the temperature consistency of the battery.

[0006] To achieve the above object, the technical solution of the present invention is realized as follows:

[0007] A battery cooling system, the system includes: a first expansion valve, a direct cooling plate heat exchanger, a controller, a compressor, and a battery direct cooling plate arranged outside the battery;

[0008] The direct cooling plate heat exchanger includes a first heat exchange circuit and a second heat exchange circuit;

[0009] The inlet of the first heat exchange circuit is connected to the outlet of the compressor, and the first heat exchange circuit is used to receive the refrigerant with a higher temperature output by the compressor; the outlet of the first heat exchange circuit is connected to the inlet of the first expansion valve, and the outlet of the first expansion valve is connected to the inlet of the battery direct cooling plate;

[0010] The inlet of the second heat exchange circuit is connected to the outlet of the battery direct cooling plate, and the second heat exchange circuit is used to receive the refrigerant at a lower temperature output by the battery direct cooling plate; the outlet of the second heat exchange circuit is connected to the inlet of the compressor; the direct cooling plate heat exchanger is used for heat exchange through the temperature difference between the first heat exchange circuit and the second heat exchange circuit;

[0011] The controller is used to adjust the heat exchange amount of the direct cooling plate heat exchanger by controlling the opening degree of the first expansion valve.

[0012] A battery cooling method, the method includes:

[0013] Determine the superheat degree at the outlet of the direct cooling plate heat exchanger;

[0014] By adjusting the heat exchange amount of the direct cooling plate heat exchanger, make the superheat degree within the target superheat degree range, and make the dryness value at the inlet of the battery direct cooling plate within the target dryness range;

[0015] Wherein, when the superheat degree is within the target superheat degree range, the dryness value at the outlet of the battery direct cooling plate is within the target dryness range.

[0016] Compared with the prior art, the battery cooling system and method of the present invention have the following advantages:

[0017] A battery cooling system and method provided by an embodiment of the present invention include: a first expansion valve, a direct cooling plate heat exchanger, a controller, a compressor, and a battery direct cooling plate arranged outside the battery; the direct cooling plate heat exchanger includes a first heat exchange circuit and a second heat exchange circuit; the inlet of the first heat exchange circuit is connected to the outlet of the compressor, and the first heat exchange circuit is used to receive the refrigerant at a higher temperature output by the compressor; the outlet of the first heat exchange circuit is connected to the inlet of the first expansion valve, and the outlet of the first expansion valve is connected to the inlet of the battery direct cooling plate; the inlet of the second heat exchange circuit is connected to the outlet of the battery direct cooling plate, and the second heat exchange circuit is used to receive the refrigerant at a lower temperature output by the battery direct cooling plate; the outlet of the second heat exchange circuit is connected to the inlet of the compressor; the direct cooling plate heat exchanger is used for heat exchange through the temperature difference between the first heat exchange circuit and the second heat exchange circuit; the controller is used to adjust the heat exchange amount of the direct cooling plate heat exchanger by controlling the opening degree of the first expansion valve; in the embodiment of the present invention, the direct cooling plate heat exchanger can exchange heat between the low-temperature refrigerant output by the battery direct cooling plate and the high-temperature refrigerant before the first expansion valve. By adjusting the first expansion valve, on the basis of avoiding the excessive temperature at the outlet of the battery direct cooling plate, the ideal superheat degree at the outlet of the direct cooling plate heat exchanger is ensured, and the refrigerant at the outlet of the battery direct cooling plate is in the two-phase state interval with the ideal dryness, and at the same time, the problem of large temperature difference between the refrigerants at different positions of the battery direct cooling plate is solved. Description of the Drawings

[0018] The accompanying drawings that form a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0019] Figure 1 is a structural diagram of a cooling system according to an embodiment of the present invention;

[0020] Figure 2 is a structural diagram of another cooling system according to an embodiment of the present invention;

[0021] Figure 3 is a structural diagram of another cooling system according to an embodiment of the present invention;

[0022] Figure 4 is a structural diagram of another cooling system according to an embodiment of the present invention;

[0023] Figure 5 is a step flowchart of a battery cooling method according to an embodiment of the present invention.

[0024] Reference numerals: direct cooling plate heat exchanger 10, first heat exchange circuit 11, second heat exchange circuit 12, battery direct cooling plate 20, compressor 30, first expansion valve 40, second expansion valve 41, first sensor 50, second sensor 51, third sensor 55, fourth sensor 56, fifth sensor 57, sixth sensor 53, seventh sensor 54, eighth sensor 80, external heat exchanger 60, internal heat exchanger 70. Detailed Embodiments

[0025] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0026] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0027] Referring to Figure 1 , there is shown a structural diagram of a cooling system according to an embodiment of the present invention. The system includes: a first expansion valve 40, a direct cooling plate heat exchanger 10, a controller, a compressor 30, and a battery direct cooling plate 20 provided outside the battery; the direct cooling plate heat exchanger 10 includes a first heat exchange circuit 11 and a second heat exchange circuit 12; the inlet of the first heat exchange circuit 11 is connected to the outlet of the compressor 30, the outlet of the first heat exchange circuit 11 is connected to the inlet of the first expansion valve 40, and the outlet of the first expansion valve 40 is connected to the inlet of the battery direct cooling plate 20; the inlet of the second heat exchange circuit 12 is connected to the outlet of the battery direct cooling plate 20, and the outlet of the second heat exchange circuit 12 is connected to the inlet of the compressor 30; the controller is used to adjust the heat exchange amount of the direct cooling plate heat exchanger 10 by controlling the opening degree of the first expansion valve 40.

[0028] In the embodiment of the present invention, the battery direct cooling plate cools the battery surface by means of the refrigerant filled inside the battery direct cooling plate, so as to achieve the cooling of the battery. Specifically, in order to achieve a better cooling effect and ensure the uniformity of the battery surface temperature, the battery cooling system in the embodiment of the present invention needs to meet two conditions: 1. The temperature at the outlet of the battery direct cooling plate should not be too high, so as to avoid a large temperature difference between the refrigerant near the outlet of the battery direct cooling plate and the refrigerant at other positions due to the high temperature at the outlet, which affects the uniformity of the battery temperature. 2. The dryness of the refrigerant in the battery direct cooling plate is within the target dryness range, so as to avoid reducing the refrigeration effect due to the non-compliance of the dryness condition or causing damage to the upstream and downstream equipment. For example, referring to Figure 2 ..., the liquid slug damage to the compressor 30 is caused because the dryness of the coolant at the outlet of the battery direct cooling plate 20 is not in the optimal two-phase state.

[0029] Specifically, the dryness at a certain position refers to the ratio of the steam mass to the total mass at that position. For example, the inlet dryness value at the inlet of the battery direct cooling plate refers to the ratio of the mass of the steam-state coolant at the inlet to the total mass of the coolant. The superheat degree refers to the difference between the superheat temperature and the saturation temperature of the refrigerant under the same evaporation pressure. The two-phase state refers to the state in which a certain substance coexists in a gaseous and a liquid state. In the embodiment of the present invention, the refrigerant being in the optimal two-phase state means that the gaseous refrigerant and the liquid refrigerant coexist and maintain a certain ratio, that is, the refrigerant is within the target dryness range. Under this condition, the refrigeration effect of the refrigerant is better.

[0030] In the embodiment of the present invention, a direct cooling plate heat exchanger 10 including a first heat exchange circuit 11 and a second heat exchange circuit 12 can be provided at the outlet of the battery direct cooling plate 20. The direct cooling plate heat exchanger 10 can exchange heat between the low-temperature refrigerant output by the battery direct cooling plate 20 and the high-temperature refrigerant before the first expansion valve 40. By adjusting the first expansion valve 40, on the basis of avoiding too high a temperature at the outlet of the battery direct cooling plate 20, the ideal superheat degree at the outlet of the direct cooling plate heat exchanger 10 is ensured, and the refrigerant at the outlet of the battery direct cooling plate 20 is in the two-phase state interval with an ideal dryness, and at the same time, the problem of a large temperature difference between the refrigerants at different positions of the battery direct cooling plate 20 is solved.

[0031] Further, the compressor 30 outputs refrigerant at a relatively high temperature. After the refrigerant at a relatively high temperature flows into the first heat exchange circuit 11, the first heat exchange circuit 11 is maintained at a relatively high temperature. The first heat exchange circuit 11 outputs the refrigerant at a relatively high temperature to the first expansion valve 40. After the first expansion valve 40 changes the refrigerant at a relatively high temperature into a refrigerant at a relatively low temperature, it is input into the battery direct cooling plate 20. The refrigerant at a relatively low temperature output by the battery direct cooling plate 20 flows into the second heat exchange circuit 12, causing the second heat exchange circuit 12 to be maintained at a relatively low temperature. Therefore, the direct cooling plate heat exchanger 10 can utilize the temperature difference between the first heat exchange circuit 11 and the second heat exchange circuit 12 to achieve the purpose of heat exchange between the low-temperature refrigerant output by the battery direct cooling plate 20 and the high-temperature refrigerant before the first expansion valve 40.

[0032] Among them, the first heat exchange circuit 11 is affected by the second heat exchange circuit 12, and the temperature of the refrigerant in the first heat exchange circuit 11 is reduced and output to the first expansion valve 40. The first expansion valve 40 further reduces the temperature of the refrigerant and then inputs it into the battery direct cooling plate 20 for battery cooling; the second heat exchange circuit 12 is affected by the first heat exchange circuit 11, and the temperature of the refrigerant in the second heat exchange circuit 12 increases, so as to meet the requirement of superheat monitoring of the refrigerant at the outlet position of the direct cooling plate heat exchanger 10, that is, by adjusting the first expansion valve 40, the ideal superheat at the outlet of the direct cooling plate heat exchanger 10 is ensured, and at the same time, the refrigerant at the outlet of the battery direct cooling plate 20 is in the two-phase state interval of the ideal dryness, solving the problem of large temperature difference between the refrigerants at different positions of the battery direct cooling plate 20.

[0033] Specifically, when constructing the battery cooling system, the target dryness range can be determined first, and then according to the refrigeration demand during battery cooling, the target superheat range can be set, and the design goal is that when the superheat at the outlet of the direct cooling plate heat exchanger is within the target superheat range, the outlet dryness value at the outlet of the battery direct cooling plate is within the target dryness range, so as to ensure that the refrigerant state at the outlet of the battery direct cooling plate is the best two-phase state.

[0034] Specifically, refer to Figure 1, by adjusting the opening degree of the first expansion valve 40 at the inlet of the battery direct cooling plate 20, the flow rate of the first expansion valve 40 can be adjusted, thereby changing the superheat at the outlet of the direct cooling plate heat exchanger 10, making the refrigerant in the battery direct cooling plate 20 in a two-phase evaporation state, achieving the change of the heat exchange amount of the direct cooling plate heat exchanger 10 and the inlet dryness value at the inlet of the battery direct cooling plate 20, and when adjusting the superheat at the outlet of the direct cooling plate heat exchanger 10 to the target superheat range and simultaneously adjusting the inlet dryness value at the inlet of the battery direct cooling plate 20 to the target dryness range, the adjustment target is achieved. At this time, since the superheat at the outlet of the direct cooling plate heat exchanger 10 is within the target superheat range, the outlet of the direct cooling plate heat exchanger 10 is in a superheat critical or small superheat state. In this state, it can be ensured that the outlet dryness value at the outlet of the battery direct cooling plate 20 is within the target dryness range. At the same time, since the inlet dryness value at the inlet of the battery direct cooling plate 20 is also adjusted to the target dryness range, it is ensured that the refrigerant at each position in the battery direct cooling plate 20 is in the best two-phase state.

[0035] Optionally, the target superheat range is 0 - 3 degrees, and the target dryness range is 0.22 - 0.88. When the target superheat range is 0 - 3 degrees, it can indicate that the outlet of the direct cooling plate heat exchanger is in a superheat critical or small superheat state, so that the outlet dryness value at the outlet of the battery direct cooling plate is within the target dryness range. That is, it can also be understood that when the outlet dryness value at the outlet of the battery direct cooling plate is within the target dryness range, the direct cooling plate heat exchanger can work normally, so that the superheat at the outlet of the direct cooling plate heat exchanger is within the target superheat range.

[0036] In the embodiment of the present invention, the direct cooling plate heat exchanger can exchange heat between the low-temperature refrigerant output by the battery direct cooling plate and the high-temperature refrigerant before the first expansion valve. By adjusting the first expansion valve, on the basis of avoiding the too high outlet temperature of the battery direct cooling plate, the ideal superheat at the outlet of the direct cooling plate heat exchanger is ensured, and the refrigerant at the outlet of the battery direct cooling plate is in the two-phase state interval with the ideal dryness. At the same time, the problem of large temperature difference between the refrigerants at different positions of the battery direct cooling plate is solved.

[0037] Optionally, referring to Figure 1 , the system further includes: a first sensor 50 and a second sensor 51 respectively electrically connected to the controller; the first sensor 50 is used to collect temperature data, and the second sensor 51 is used to collect temperature data; the first sensor 50 is arranged between the inlet position of the battery direct cooling plate 20 and the outlet position of the first expansion valve 40, and the second sensor 51 is arranged at the outlet position of the battery direct cooling plate 20.

[0038] Specifically, in the embodiments of the present invention, a dedicated dryness detection device can be used to detect the inlet dryness value at the inlet of the battery direct cooling plate, or the inlet dryness value can be calculated based on the collected temperature values at the inlet and outlet of the battery direct cooling plate and the characteristic parameters of the refrigerant. The calculation method is as follows:

[0039] Step A1: The controller obtains the first temperature value at the inlet of the battery direct cooling plate through the first sensor, obtains the second temperature value at the outlet of the battery direct cooling plate through the second sensor, and obtains the characteristic parameters of the refrigerant in the battery direct cooling plate.

[0040] Step A2: The controller calculates the inlet dryness value based on the first temperature value, the second temperature value, and the characteristic parameters.

[0041] In the embodiments of the present invention, referring to Figure 1 , the inlet dryness value can be obtained by the collected values of the first sensor 50 provided before the first expansion valve 40 at the inlet of the battery direct cooling plate 20, the collected values of the second sensor 51 provided at the outlet of the battery direct cooling plate 20, and the characteristic parameters of the refrigerant. Specifically, first, the gaseous enthalpy value and liquid enthalpy value of the refrigerant in the battery direct cooling plate 20 can be found through the characteristic parameters of the refrigerant at different temperatures, the preset characteristic parameters, and the corresponding relationships among the enthalpy value of the gaseous refrigerant and the enthalpy value of the liquid refrigerant, and then the inlet dryness value can be calculated based on the gaseous enthalpy value and the liquid enthalpy value.

[0042] In one implementation manner of the embodiments of the present invention, the direct cooling plate heat exchanger can be a thermoelectric heat exchanger, and the controller is used to adjust the heat exchange amount of the thermoelectric heat exchanger by controlling the opening degree of the first expansion valve and the input current of the thermoelectric heat exchanger.

[0043] In the embodiments of the present invention, the thermoelectric heat exchanger can adjust its heat exchange amount by changing its input current value, so that the heat exchange amount of the thermoelectric heat exchanger can be adjusted to the target superheat range, and the outlet dryness value at the outlet of the battery direct cooling plate is further within the target dryness range. Further, by adjusting the flow rate of the first expansion valve, the inlet dryness value at the inlet of the battery direct cooling plate can be within the target dryness range.

[0044] It should be noted that whether it is to adjust the input current value of the thermoelectric heat exchanger or the opening degree of the first expansion valve, it can be executed by the vehicle controller, that is, implemented by the corresponding control instructions of the controller. In addition, when adjusting the opening degree of the first expansion valve, the heat exchange amount of the thermoelectric heat exchanger can also be changed, so the operations of adjusting the input current value of the thermoelectric heat exchanger and adjusting the opening degree of the first expansion valve can be performed simultaneously.

[0045] Optionally, in another implementation manner of the embodiments of the present invention, referring to Figure 2, the system further includes: a sixth sensor 53 and a seventh sensor 54 respectively electrically connected to the controller; the sixth sensor 53 is used to collect temperature and pressure data, and the seventh sensor 54 is used to collect temperature data; the sixth sensor 53 is disposed at the inlet position of the first expansion valve 40, and the seventh sensor 54 is disposed between the inlet position of the battery direct cooling plate 20 and the outlet position of the first expansion valve 40.

[0046] In another implementation manner of the embodiment of the present invention, the direct cooling plate heat exchanger may be an aluminum heat exchanger. Adjusting the opening degree of the first expansion valve 40 can throttle the medium-temperature and high-pressure liquid refrigerant to become a low-temperature and low-pressure wet steam, so that the refrigerant in the state of low-temperature and low-pressure wet steam absorbs heat in the battery direct cooling plate to achieve a refrigeration effect. Since the structural material of the aluminum heat exchanger is already fixed, the embodiment of the present invention can directly change the inlet dryness value at the inlet of the battery direct cooling plate by adjusting the flow rate of the first expansion valve 40 to make it within the target dryness range. During the process of adjusting the first expansion valve 40, the heat exchange amount of the aluminum heat exchanger can also be changed. When the heat exchange amount of the aluminum heat exchanger is within the target superheat range, the outlet dryness value at the outlet of the battery direct cooling plate is further within the target dryness range, achieving the best two-phase state of the coolant at each position in the battery direct cooling plate.

[0047] In the embodiment of the present invention, a pressure and temperature sensor may be disposed at the outlet of the direct cooling plate heat exchanger to calculate the superheat degree at the outlet of the direct cooling plate heat exchanger based on the collected values of pressure and temperature and the characteristic parameters of the refrigerant.

[0048] Optionally, referring to Figure 1 and Figure 2 , the system further includes: an eighth sensor 80 electrically connected to the controller; the eighth sensor 80 is used to collect temperature and pressure data; the eighth sensor 80 is disposed between the outlet position of the second heat exchange circuit 12 and the inlet position of the compressor 30; the controller is further configured to adjust the flow rate of the first expansion valve 40 according to the data collected by the eighth sensor 80, so as to adjust the heat exchange amount of the direct cooling plate heat exchanger 10.

[0049] Specifically, the controller can obtain the second temperature value and the second pressure value at the outlet of the second heat exchange circuit 12 of the direct cooling plate heat exchanger and the characteristic parameters of the refrigerant in the battery direct cooling plate through the eighth sensor 80, and calculate the outlet superheat degree of the direct cooling plate heat exchanger according to the second temperature value, the second pressure value and the characteristic parameters. In the embodiment of the present invention, the dry saturation temperature of the refrigerant in the battery direct cooling plate 20 can be found first through the characteristic parameters of the refrigerant, and then the superheated steam temperature can be calculated through the collected values of the temperature and pressure sensors: the second temperature value and the second pressure value. Subtracting the dry saturation temperature from the superheated steam temperature can obtain the above-mentioned superheat degree.

[0050] Optionally, in another implementation manner of the embodiment of the present invention, refer to Figure 3 , the system further includes: a third sensor 55, a fourth sensor 56, and a fifth sensor 57 respectively connected to the controller; the third sensor 55, the fourth sensor 56, and the fifth sensor 57 are all used to collect temperature data; the third sensor 55 is arranged between the inlet position of the battery direct cooling plate 20 and the outlet position of the first expansion valve 40, the fourth sensor 56 is arranged at the middle position of the battery direct cooling plate 20, and the fifth sensor 57 is arranged at the outlet position of the battery direct cooling plate 20; the controller is further used to determine a first temperature difference between the inlet position and the middle position of the battery direct cooling plate 20 and a second temperature difference between the inlet position and the outlet position of the battery direct cooling plate 20 according to the data collected by the third sensor 55, the fourth sensor 56, and the fifth sensor 57; the controller is further used to adjust the opening degree of the first expansion valve 40 according to the first temperature difference, the second temperature difference, and the first temperature threshold, so that the first temperature difference and the second temperature difference are less than the first temperature threshold.

[0051] In another implementation manner of the embodiment of the present invention, it is also possible to respectively arrange temperature sensors at the inlet position, the middle position, and the outlet position of the battery direct cooling plate 20, and determine a first temperature difference between the inlet position and the middle position of the battery direct cooling plate 20 and a second temperature difference between the inlet position and the outlet position of the battery direct cooling plate 20 through the readings of the temperature sensors, and reflect the temperature uniformity of the battery direct cooling plate 20 by the magnitudes of the absolute values of the first temperature difference and the second temperature difference. When the controller detects that the first temperature difference is greater than the second temperature threshold, it can reduce the opening degree of the first expansion valve 40, so that the first temperature difference gradually decreases until it decreases to the normal state; when it detects that the second temperature difference is greater than the second temperature threshold, it can increase the opening degree of the first expansion valve 40, so that the second temperature difference gradually decreases until it decreases to the normal state, thereby achieving the purpose of controlling the temperature uniformity of each position of the battery direct cooling plate 20.

[0052] It should be noted that, refer to Figure 3 , when the direct cooling plate heat exchanger 10 is a thermoelectric heat exchanger, the controller can further adjust the input current value of the thermoelectric heat exchanger by collecting the temperature and pressure data collected by the eighth sensor 80, so as to change the outlet superheat degree of the second heat exchange circuit of the thermoelectric heat exchanger, so that the outlet superheat degree is within the target superheat degree range.

[0053] Optionally, refer to Figure 1 , the system further includes: an external heat exchanger 60, an internal heat exchanger 70, and a second expansion valve 41; the inlet of the external heat exchanger 60 is connected to the outlet of the compressor 30, and the outlet of the external heat exchanger 60 is connected to the inlet of the first heat exchange circuit 11; the inlet of the internal heat exchanger 70 communicates with the outlet of the second expansion valve 41, and the outlet of the internal heat exchanger 70 communicates with the inlet of the compressor 30.

[0054] Among them, referring to Figure 1 , the inlet of the second expansion valve 41 is connected between the outlet of the external heat exchanger 60 and the first heat exchange circuit 11, or referring to Figure 4 , the inlet of the second expansion valve 41 is connected between the first heat exchange circuit 11 and the inlet of the first expansion valve 40.

[0055] In the embodiment of the present invention, the high-temperature and high-pressure refrigerant comes out of the compressor and enters the external heat exchanger to exchange heat and cool with the external environment. The refrigerant output from the external heat exchanger is throttled and depressurized through the expansion valve, becoming a low-temperature and low-pressure refrigerant. The low-temperature refrigerant enters the internal heat exchanger or the battery direct cooling plate to cool the passenger compartment and the battery in the vehicle, and then the refrigerant returns to the compressor inlet for recycling.

[0056] Furthermore, by adjusting the opening degree of the first expansion valve 40, the dryness of the coolant input to the inlet of the battery direct cooling plate 20 can be adjusted, and by adjusting the opening degree of the second expansion valve 41, the dryness of the coolant input to the inlet of the internal heat exchanger 70 can be adjusted.

[0057] Specifically, referring to Figure 1 , by adjusting the opening degree of the first expansion valve 40 at the inlet of the battery direct cooling plate 20, the refrigerant in the battery direct cooling plate 20 can be in a two-phase evaporation state, realizing the change of the heat exchange amount of the direct cooling plate heat exchanger 10 and the inlet dryness value at the inlet of the battery direct cooling plate 20, and when adjusting the superheat degree at the outlet of the direct cooling plate heat exchanger 10 to the target superheat degree range and simultaneously adjusting the inlet dryness value at the inlet of the battery direct cooling plate 20 to the target dryness range, the adjustment target is achieved. At this time, since the superheat degree at the outlet of the direct cooling plate heat exchanger 10 is within the target superheat degree range, the outlet of the direct cooling plate heat exchanger 10 is in a superheat critical or small superheat degree state. In this state, it can be ensured that the outlet dryness value at the outlet of the battery direct cooling plate 20 is within the target dryness range, and at the same time, since the inlet dryness value at the inlet of the battery direct cooling plate 20 is also adjusted to the target dryness range, it is ensured that the refrigerant at each position in the battery direct cooling plate 20 is in the best two-phase state.

[0058] In another implementation manner, referring to Figure 4 . The structure diagram of another battery cooling system according to the embodiment of the present invention is shown, where the inlet of the second expansion valve 41 is connected between the first heat exchange circuit 11 and the inlet of the first expansion valve 40. In the embodiment of the present invention, Figure 1 The structure of the connection between the direct cooling plate heat exchanger 10 and the battery branch of the battery direct cooling plate 20 is shown, Figure 4 The structure of the connection between the direct cooling plate heat exchanger 10 of the battery direct cooling plate 20 and the high-temperature main circuit of the external heat exchanger 60 is shown, that is Figure 1In the structure, the direct cooling plate heat exchanger directly exchanges heat with the battery branch output by the battery direct cooling plate outside the battery. Figure 4 In the structure, the direct cooling plate heat exchanger directly exchanges heat with the high-temperature main path output by the external heat exchanger. The embodiments of the present invention do not limit the specific structural manner.

[0059] In summary, a battery cooling system provided by an embodiment of the present invention includes: a first expansion valve, a direct cooling plate heat exchanger, a controller, a compressor, and a battery direct cooling plate arranged outside the battery; the direct cooling plate heat exchanger includes a first heat exchange circuit and a second heat exchange circuit; the inlet of the first heat exchange circuit is connected to the outlet of the compressor, and the first heat exchange circuit is used to receive the refrigerant at a relatively high temperature output by the compressor; the outlet of the first heat exchange circuit is connected to the inlet of the first expansion valve, and the outlet of the first expansion valve is connected to the inlet of the battery direct cooling plate; the inlet of the second heat exchange circuit is connected to the outlet of the battery direct cooling plate, and the second heat exchange circuit is used to receive the refrigerant at a relatively low temperature output by the battery direct cooling plate; the outlet of the second heat exchange circuit is connected to the inlet of the compressor; the direct cooling plate heat exchanger is used to perform heat exchange through the temperature difference between the first heat exchange circuit and the second heat exchange circuit; the controller is used to adjust the heat exchange amount of the direct cooling plate heat exchanger by controlling the opening degree of the first expansion valve; in the embodiments of the present invention, the direct cooling plate heat exchanger can exchange heat between the low-temperature refrigerant output by the battery direct cooling plate and the high-temperature refrigerant before the first expansion valve. By adjusting the first expansion valve, on the basis of avoiding the excessive temperature at the outlet of the battery direct cooling plate, the ideal superheat degree at the outlet of the direct cooling plate heat exchanger is ensured, and the refrigerant at the outlet of the battery direct cooling plate is in the two-phase state interval with the ideal dryness, and at the same time, the problem of large temperature difference between the refrigerants at different positions of the battery direct cooling plate is solved.

[0060] Refer to Figure 5 , which shows the structural diagram of a battery cooling method according to an embodiment of the present invention, applied to a controller in a battery cooling system, including:

[0061] Step 101: Determine the superheat degree at the outlet of the direct cooling plate heat exchanger.

[0062] Step 102: Adjust the heat exchange amount of the direct cooling plate heat exchanger to make the superheat degree within the target superheat degree range and make the inlet dryness value of the battery direct cooling plate within the target dryness range.

[0063] Wherein, when the superheat degree is within the target superheat degree range, the outlet dryness value of the battery direct cooling plate is within the target dryness range.

[0064] In the embodiments of the present invention, a special dryness detection device can be used to detect the inlet dryness value at the inlet of the battery direct cooling plate, or the inlet dryness value can be calculated through the collected temperature values at the inlet and outlet of the battery direct cooling plate and the characteristic parameters of the refrigerant.

[0065] Further, in the embodiment of the present invention, an eighth sensor 80 for collecting pressure and temperature data may be provided at the outlet of the direct-cooling plate heat exchanger, so as to calculate the superheat degree at the outlet of the direct-cooling plate heat exchanger based on the collected values of pressure and temperature and the characteristic parameters of the refrigerant.

[0066] A direct-cooling plate heat exchanger 10 including a first heat exchange circuit 11 and a second heat exchange circuit 12 may be provided at the outlet of the battery direct-cooling plate 20. The direct-cooling plate heat exchanger 10 can exchange heat between the low-temperature refrigerant output by the battery direct-cooling plate 20 and the high-temperature refrigerant before the first expansion valve 40. By adjusting the first expansion valve 40, on the basis of avoiding the excessive temperature at the outlet of the battery direct-cooling plate 20, the ideal superheat degree at the outlet of the direct-cooling plate heat exchanger 10 is ensured, and the refrigerant at the outlet of the battery direct-cooling plate 20 is in the two-phase state interval with the ideal dryness. At the same time, the problem of large temperature difference between the refrigerants at different positions of the battery direct-cooling plate 20 is solved.

[0067] When constructing the cooling system of the battery, the target dryness range may be determined first, and then the target superheat degree range may be set according to the refrigeration demand during battery cooling. With the superheat degree at the outlet of the direct-cooling plate heat exchanger being within the target superheat degree range, the outlet dryness value at the outlet of the battery direct-cooling plate is within the target dryness range as the design goal, so as to ensure that the refrigerant state at the outlet of the battery direct-cooling plate is the best two-phase state.

[0068] Specifically, referring to Figure 1 , by adjusting the opening degree of the first expansion valve 40 at the inlet of the battery direct-cooling plate 20, the flow rate of the first expansion valve 40 can be adjusted, and then the superheat at the outlet of the direct-cooling plate heat exchanger 10 can be changed, so that the refrigerant in the battery direct-cooling plate 20 is in the two-phase evaporation state, realizing the change of the heat exchange amount of the direct-cooling plate heat exchanger 10 and the inlet dryness value at the inlet of the battery direct-cooling plate 20. When the superheat degree at the outlet of the direct-cooling plate heat exchanger 10 is adjusted to the target superheat degree range and the inlet dryness value at the inlet of the battery direct-cooling plate 20 is adjusted to the target dryness range, the adjustment goal is achieved. At this time, since the superheat degree at the outlet of the direct-cooling plate heat exchanger 10 is within the target superheat degree range, the outlet of the direct-cooling plate heat exchanger 10 is in the superheat critical or small superheat degree state. In this state, it can be ensured that the outlet dryness value at the outlet of the battery direct-cooling plate 20 is within the target dryness range. At the same time, since the inlet dryness value at the inlet of the battery direct-cooling plate 20 is also adjusted to the target dryness range, it is ensured that the refrigerants at all positions in the battery direct-cooling plate 20 are in the best two-phase state.

[0069] Optionally, the method may further include:

[0070] Step 103: When it is detected that the temperature difference between the inlet position and the middle position of the battery direct cooling plate is less than or equal to the second temperature threshold, and the temperature difference between the inlet position and the outlet position of the battery direct cooling plate is greater than the second temperature threshold, the operation of adjusting the opening degree of the first expansion valve is performed multiple times at a preset time interval.

[0071] In the embodiments of the present invention, for some extreme working conditions of the whole vehicle, there will be a situation where the refrigeration capacity of the entire refrigeration circuit cannot meet the large refrigeration requirements of the indoor heat exchanger and the battery direct cooling plate at the same time. At this time, considering the thermal comfort of the passengers and drivers, usually the refrigeration capacity is preferentially allocated to the indoor heat exchanger to meet the refrigeration requirements of the passenger compartment, and the remaining performance is distributed to the battery direct cooling plate. At this time, when the battery also has a large refrigeration requirement, but the refrigerant flow rate entering the battery direct cooling plate is small, the refrigerant will complete intense boiling heat exchange in the first half of the battery direct cooling plate to cool the battery, and the refrigerant is in a superheated state in the second half, resulting in obvious temperature non-uniformity of the battery direct cooling plate.

[0072] To solve this problem, in the embodiments of the present invention, the controller can perform the operations of opening and closing the first expansion valve multiple times at a preset time interval when it is detected that the temperature difference between the inlet position and the middle position of the battery direct cooling plate is less than or equal to the second temperature threshold, and the temperature difference between the inlet position and the outlet position of the battery direct cooling plate is greater than the second temperature threshold. By operating to adjust the opening degree of the first expansion valve multiple times, a pulsating impact of the refrigerant can be formed in the battery direct cooling plate. Under the action of the pulsating impact, the superheated state of the refrigerant in the second half of the battery direct cooling plate can be alleviated, thereby improving the problem of obvious temperature non-uniformity of the battery direct cooling plate. Among them, the operation of adjusting the opening degree of the first expansion valve can be the operation of opening / closing the first expansion valve, that is, adjusting the opening degree of the first expansion valve from the maximum value to the minimum value. In addition, the operation of adjusting the opening degree of the first expansion valve can also be the operation of adjusting the opening degree of the first expansion valve back and forth between a larger value and a smaller value. For example, adjusting the opening degree of the first expansion valve from 50% to 100% and from 100% to 50%.

[0073] In summary, a battery cooling method provided by an embodiment of the present invention includes: determining the superheat degree at the outlet of the direct cooling plate heat exchanger; adjusting the heat exchange amount of the direct cooling plate heat exchanger so that the superheat degree is within a target superheat degree range and the dryness value at the inlet of the battery direct cooling plate is within a target dryness range; wherein, when the superheat degree is within the target superheat degree range, the dryness value at the outlet of the battery direct cooling plate is within the target dryness range; in the embodiment of the present invention, the direct cooling plate heat exchanger can perform heat exchange between the low-temperature refrigerant output by the battery direct cooling plate and the high-temperature refrigerant before the first expansion valve. By adjusting the first expansion valve, on the basis of avoiding too high an outlet temperature of the battery direct cooling plate, an ideal superheat degree at the outlet of the direct cooling plate heat exchanger is ensured, and the refrigerant at the outlet of the battery direct cooling plate is in an ideal dryness two-phase state interval. At the same time, the problem of large temperature difference between refrigerants at different positions of the battery direct cooling plate is solved.

[0074] An embodiment of the present invention further provides a vehicle, and the vehicle includes a battery and a battery cooling system.

[0075] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the above-described systems, devices, and units can refer to the corresponding processes in the foregoing method embodiments and will not be described herein again.

[0076] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0077] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present invention and should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A battery cooling system, characterized in that, The system includes: a first expansion valve, a direct cooling plate heat exchanger, a controller, a compressor, a battery direct cooling plate disposed outside the battery, a first sensor and a second sensor respectively electrically connected to the controller; The direct cooling plate heat exchanger includes a first heat exchange circuit and a second heat exchange circuit; The inlet of the first heat exchange circuit is connected to the outlet of the compressor. The first heat exchange circuit is used to receive the refrigerant at a relatively high temperature output by the compressor. The outlet of the first heat exchange circuit is connected to the inlet of the first expansion valve. The outlet of the first expansion valve is connected to the inlet of the battery direct cooling plate; The inlet of the second heat exchange circuit is connected to the outlet of the battery direct cooling plate. The second heat exchange circuit is used to receive the refrigerant at a relatively low temperature output by the battery direct cooling plate. The outlet of the second heat exchange circuit is connected to the inlet of the compressor. The direct cooling plate heat exchanger is used to perform heat exchange through the temperature difference between the first heat exchange circuit and the second heat exchange circuit; The controller is used to adjust the heat exchange amount of the direct cooling plate heat exchanger by controlling the opening degree of the first expansion valve and the input current of the direct cooling plate heat exchanger, and the heat exchange amount is within a preset target superheat range; The first sensor is used to collect temperature data, and the second sensor is used to collect temperature data; The first sensor is disposed between the inlet position of the battery direct cooling plate and the outlet position of the first expansion valve. The first sensor is used to obtain a first temperature value at the inlet of the battery direct cooling plate. The second sensor is disposed at the outlet position of the battery direct cooling plate. The second sensor is used to obtain a second temperature value at the outlet of the battery direct cooling plate and the characteristic parameters of the refrigerant in the battery direct cooling plate; The controller is further used to calculate an inlet dryness value of the battery direct cooling plate according to the first temperature value, the second temperature value and the characteristic parameters. The inlet dryness value is within a preset target dryness range, and the target superheat range is determined according to the target dryness range; 2. The system according to claim 1, wherein The direct cooling plate heat exchanger is a thermoelectric heat exchanger. The controller is used to adjust the heat exchange amount of the thermoelectric heat exchanger by controlling the opening degree of the first expansion valve and the input current of the thermoelectric heat exchanger; 3. The system according to claim 1, wherein The system further includes: a third sensor, a fourth sensor and a fifth sensor respectively connected to the controller. The third sensor, the fourth sensor and the fifth sensor are all used to collect temperature data; The third sensor is disposed between the inlet position of the battery direct cooling plate and the outlet position of the first expansion valve. The fourth sensor is disposed at the middle position of the battery direct cooling plate. The fifth sensor is disposed at the outlet position of the battery direct cooling plate; The controller is further used to determine a first temperature difference between the inlet position and the middle position of the battery direct cooling plate and a second temperature difference between the inlet position and the outlet position of the battery direct cooling plate according to the data collected by the third sensor, the fourth sensor and the fifth sensor; The controller is further configured to adjust the opening degree of the first expansion valve according to the first temperature difference, the second temperature difference, and a first temperature threshold, such that the first temperature difference and the second temperature difference are less than the first temperature threshold.

4. The system according to claim 1, wherein The system further includes: a sixth sensor and a seventh sensor, both electrically connected to the controller; the sixth sensor is configured to collect temperature and pressure data, and the seventh sensor is configured to collect temperature data; The sixth sensor is disposed at the inlet position of the first expansion valve, and the seventh sensor is disposed between the inlet position of the battery direct cooling plate and the outlet position of the first expansion valve.

5. The system according to any one of claims 1-4, characterized in that, The system further includes: an eighth sensor electrically connected to the controller; the eighth sensor is configured to collect temperature and pressure data; The eighth sensor is disposed between the outlet position of the second heat exchange loop and the inlet position of the compressor. The controller is further configured to adjust the flow rate of the first expansion valve according to the data collected by the eighth sensor, so as to adjust the heat exchange amount of the direct cooling plate heat exchanger.

6. The system according to claim 1, characterized in that, The system further includes: an external heat exchanger; The inlet of the external heat exchanger is connected to the outlet of the compressor, and the outlet of the external heat exchanger is connected to the inlet of the first heat exchange loop.

7. The system according to claim 6, characterized in that The system further includes: an internal heat exchanger and a second expansion valve; The inlet of the internal heat exchanger communicates with the outlet of the second expansion valve, and the outlet of the internal heat exchanger communicates with the inlet of the compressor; the inlet of the second expansion valve communicates between the outlet of the external heat exchanger and the first heat exchange loop, or the inlet of the second expansion valve communicates between the first heat exchange loop and the inlet of the first expansion valve.

8. A battery cooling method, applied to a controller in the battery cooling system according to any one of claims 1 to 7, characterized in that, The method includes: Determining the superheat degree at the outlet of the direct cooling plate heat exchanger; By adjusting the heat exchange amount of the direct cooling plate heat exchanger, such that the superheat degree is within a target superheat degree range, and the dryness value at the inlet of the battery direct cooling plate is within a target dryness range, and the heat exchange amount of the direct cooling plate heat exchanger is adjusted by the controller controlling the opening degree of the first expansion valve and the input current of the direct cooling plate heat exchanger; Wherein, when the superheat degree is within the target superheat degree range, the dryness value at the outlet of the battery direct cooling plate is within the target dryness range; The method further includes: Obtaining a first temperature at the inlet of the battery direct cooling plate, a second temperature at the outlet of the battery direct cooling plate, and characteristic parameters of the refrigerant in the battery direct cooling plate; Calculating the dryness value at the inlet of the battery direct cooling plate according to the first temperature value, the second temperature value, and the characteristic parameters, the inlet dryness value is within the target dryness range, and the target superheat degree range is determined according to the target dryness range.

9. The method according to claim 8, wherein When it is detected that the temperature difference between the inlet position and the middle position of the battery direct cooling plate is less than or equal to a second temperature threshold, and the temperature difference between the inlet position and the outlet position of the battery direct cooling plate is greater than the second temperature threshold, then at a preset time interval, perform multiple operations of adjusting the opening degree of the first expansion valve.

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