Battery cooling system

Abstract

To appropriately perform suppression of a sub-cool abnormality and suppression of a surging phenomenon in a battery cooling system.SOLUTION: A battery cooling system comprises a refrigeration cycle for forming a circuit, in which a coolant is circulated, and a control device. The refrigeration cycle includes: a compressor of which the compression system is a speed type; a condenser; a fan which cools the condenser; a plurality of evaporators each disposed correspondingly to each of a plurality of batteries; a plurality of branch channels each connected to each of one-side ends of the plurality of evaporators; and a plurality of decompressors each disposed in each of the plurality of branch channels. The control device adjusts at least one of a rotation speed of the fan and a rotation speed of the compressor so as to suppress a surging phenomenon in a case where it is determined that the surging phenomenon may occur and adjusts at least one of the rotation speed of the fan and the rotation speed of the compressor so as to suppress a sub-cool abnormality in a case where it is determined that the surging phenomenon may not occur but the sub-cool abnormality may occur.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a battery cooling system for cooling a plurality of batteries. [Background technology]

[0002] JP 2020-184427 A (Patent Document 1) discloses a battery cooling system that cools multiple battery modules. The refrigeration cycle installed in this battery cooling system is configured to branch the refrigerant supplied from a condenser into multiple branch flow paths in order to cool each of the multiple battery modules, and to arrange an expansion valve and an evaporator in each of the multiple branch flow paths, and to cool each battery module with each evaporator. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-184427 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a refrigeration cycle configuration in which an expansion valve (pressure reducer) and an evaporator are arranged in each of a plurality of branch flow paths, such as the battery cooling system disclosed in JP 2020-184427 A, in order to evenly cool a plurality of battery modules, it is desirable to distribute the refrigerant to each of the plurality of branch flow paths in equal amounts. To achieve this, it is desirable to maintain the refrigerant in a liquid state (subcooled state) in the plurality of branch flow paths. However, depending on the temperature of each battery module and the outside air temperature around the condenser, a subcooling anomaly may occur in which the refrigerant in the plurality of branch flow paths does not become liquid. If the rotation speed of the compressor or the rotation speed of the fan that cools the condenser is set to an excessively high value as a countermeasure, the power consumption of the compressor and the fan may become unnecessarily large, and there is a concern that the cruising distance of the vehicle equipped with the battery module may be reduced. In addition, if the compression method of the compressor is a speed type, a surging phenomenon may occur depending on the operating state of the compressor, causing the compressor to be unable to operate normally. Moreover, since the surging phenomenon is likely to cause a system failure, the surging phenomenon is more likely to cause serious problems in the system than the subcooling anomaly.

[0005] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to effectively suppress subcooling anomalies and surging phenomena in a battery cooling system equipped with a refrigeration cycle in which a pressure reducer and an evaporator are arranged in each of a plurality of branch flow paths. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, there is provided a battery cooling system as described below. (Item 1) The battery cooling system includes a refrigeration cycle forming a circuit through which a refrigerant circulates, and a control device. The refrigeration cycle includes a compressor, a condenser, a fan for cooling the condenser, a plurality of evaporators arranged corresponding to the plurality of batteries, a first flow path connected to a discharge port of the compressor and one end of the condenser, a second flow path connecting the other end of the condenser and one ends of the plurality of evaporators, and a third flow path connecting the other ends of the plurality of evaporators and a suction port of the compressor. The compressor is a speed type compressor. The second flow path includes a plurality of branch flow paths each connected to one ends of the plurality of evaporators. The battery cooling system further includes a plurality of pressure reducers arranged in the plurality of branch flow paths, a first detection means for detecting a state of the refrigerant upstream of the pressure reducer in the second flow path, and a second detection means for detecting a state of the compressor. The control device is configured to determine, based on the detection result of the first detection means, whether a subcooling anomaly will occur in which the refrigerant will not be in a liquid state upstream of the pressure reducer in the second flow path; determine, based on the detection result of the second detection means, whether a surging phenomenon of the compressor will occur; and, when it is determined that surging will occur, adjust at least one of the fan rotation speed and the compressor rotation speed so as to suppress the surging phenomenon; and, when it is determined that surging will not occur but a subcooling anomaly will occur, adjust at least one of the fan rotation speed and the compressor rotation speed so as to suppress the subcooling anomaly.

[0007] In the above configuration, when it is determined that surging will not occur (i.e., the compressor can operate normally) and when it is determined that subcooling anomaly will occur (i.e., the refrigerant will not be in a liquid state upstream of the pressure reducer in the second flow path), at least one of the fan rotation speed and the compressor rotation speed is adjusted to suppress the subcooling anomaly. This makes it difficult for the subcooling anomaly to occur. On the other hand, when it is determined that surging will occur, at least one of the fan rotation speed and the compressor rotation speed is adjusted to at least suppress the surging phenomenon, regardless of the determination result of the subcooling anomaly. This makes it possible to more reliably avoid the surging phenomenon.

[0008] The battery cooling system described in the above item 1 may have a configuration described in any one of items 2 to 5 below.

[0009] (Item 2) The battery cooling system described in item 1 further has the following features. The control device is configured to determine whether the state of the refrigerant corresponds to a first state in which a subcooling abnormality occurs, a second state in which a subcooling abnormality is unlikely to occur, or a third state which is neither the first state nor the second state, in determining whether a subcooling abnormality occurs. The control device is configured to accelerate at least one of the rotation speed of the fan and the rotation speed of the compressor when it is determined that no surging phenomenon occurs and the state of the refrigerant is in the first state, to decelerate at least one of the rotation speed of the fan and the rotation speed of the compressor when it is determined that no surging phenomenon occurs and the state of the refrigerant is in the second state, and to keep both the rotation speed of the fan and the rotation speed of the compressor unchanged when it is determined that no surging phenomenon occurs and the state of the refrigerant is in the third state.

[0010] According to the above configuration, when a subcooling abnormality occurs, at least one of the rotation speed of the fan and the rotation speed of the compressor is accelerated, which makes it easier to accurately avoid the subcooling abnormality. Also, when a subcooling abnormality is unlikely to occur, at least one of the rotation speed of the fan and the rotation speed of the compressor is decelerated, which makes it possible to reduce energy consumption while maintaining the refrigerant in a liquid state upstream of the pressure reducer in the second flow path.

[0011] (Item 3) The battery cooling system described in item 2 further has the following features. The control device is configured to execute determining whether or not the rotation speed of the fan is less than an upper limit value, and determining whether or not the rotation speed of the compressor is greater than a lower limit value. The control device is configured to accelerate the rotation speed of the fan when it is determined that the surging phenomenon does not occur, the state of the refrigerant is in the first state, and the rotation speed of the fan is less than the upper limit value, to accelerate the rotation speed of the compressor when it is determined that the surging phenomenon does not occur, the state of the refrigerant is in the first state, and the rotation speed of the fan is not less than the upper limit value, to decelerate the rotation speed of the compressor when it is determined that the surging phenomenon does not occur, the state of the refrigerant is in the second state, and the rotation speed of the compressor is greater than the lower limit value, and to decelerate the rotation speed of the fan when it is determined that the surging phenomenon does not occur, the state of the refrigerant is in the second state, and the rotation speed of the compressor is not greater than the lower limit value.

[0012] Usually, the energy consumed to drive the compressor that draws in and discharges the refrigerant is greater than the energy consumed to drive the fan that cools the condenser. According to the above configuration, when a subcooling abnormality occurs, the drive amount of the fan is increased (the rotation speed is increased) in preference to the compressor, making it easier to accurately avoid the subcooling abnormality while suppressing energy consumption. Also, when a subcooling abnormality is unlikely to occur, the drive amount of the compressor is reduced (the rotation speed is reduced) in preference to the fan, making it possible to reduce energy consumption while maintaining the refrigerant in a liquid state upstream of the pressure reducer in the second flow path.

[0013] (4) The battery cooling system according to any one of the first to third aspects further has the following features. The control device is configured to execute the following: determining whether the rotation speed of the fan is less than a fan rotation upper limit value; determining whether the rotation speed of the compressor is less than an upper limit value; and determining whether the rotation speed of the compressor is greater than a lower limit value. The control device is configured to accelerate the rotation speed of the fan when it is determined that the surging phenomenon will occur when the rotation speed of the fan is less than the fan rotation upper limit value; and to accelerate or decelerate the rotation speed of the compressor so as to suppress the surging phenomenon when it is determined that the surging phenomenon will occur when the rotation speed of the fan is not less than the fan rotation upper limit value and the rotation speed of the compressor is greater than the lower limit value and less than the upper limit value.

[0014] According to the above configuration, when surging occurs, the amount of drive of the fan is increased (the rotation speed is increased) in preference to the compressor, which makes it easier to accurately avoid the surging phenomenon while suppressing energy consumption.

[0015] (Item 5) The battery cooling system according to any one of items 1 to 4 further has the following features. The first detection means includes a pressure sensor that detects the pressure of the refrigerant upstream of the pressure reducer in the second flow path, and a temperature sensor that detects the temperature of the refrigerant upstream of the pressure reducer in the second flow path. The control device is configured to calculate a saturation temperature of the refrigerant upstream of the pressure reducer in the second flow path based on the pressure of the refrigerant detected by the pressure sensor, and determine whether or not a subcooling anomaly occurs based on the saturation temperature and the temperature of the refrigerant detected by the temperature sensor. The second detection means includes a first pressure sensor that detects a suction pressure that is the pressure of the refrigerant on the suction side of the compressor, a second pressure sensor that detects a discharge pressure that is the pressure of the refrigerant on the discharge side of the compressor, and a flow rate sensor that detects a flow rate of the refrigerant flowing through the compressor. The control device is configured to identify an operating point of the compressor using the suction pressure, discharge pressure, and flow rate detected by the second detection means, and determine whether or not a surging phenomenon occurs based on whether or not the identified operating point is included in a predetermined surging region. In addition, the above-mentioned pressure sensor, temperature sensor, first pressure sensor, second pressure sensor, and flow sensor are concepts that not only directly detect the pressure, temperature, and flow rate of the refrigerant at the corresponding locations, but also include configurations that estimate the pressure, temperature, and flow rate of the refrigerant at the corresponding locations from other detection values ​​in the battery cooling system.

[0016] According to the above configuration, it becomes easier to appropriately determine whether or not a subcooling abnormality occurs and whether or not a surging phenomenon occurs. Effect of the Invention

[0017] According to the present disclosure, in a battery cooling system having a refrigeration cycle in which a pressure reducer and an evaporator are arranged in each of a plurality of branch flow paths, it is possible to effectively suppress subcooling anomalies and surging phenomena. [Brief description of the drawings]

[0018] [Figure 1] 1 is a diagram showing the overall configuration of a battery cooling system according to an embodiment of the present disclosure. [Diagram 2]2 is a diagram showing an example of the arrangement of a plurality of branch flow paths and a plurality of pressure reducers in the battery cooling system shown in FIG. 1. [Diagram 3] 5 is a flowchart illustrating an example of a processing procedure of a control device according to an embodiment of the present disclosure. [Figure 4] 4 is a flowchart showing details of a process related to a first determination shown in FIG. 3. [Diagram 5] 4 is a flowchart showing details of the process relating to the second determination shown in FIG. 3. [Figure 6] 6 is a flowchart showing the details of a process for avoiding the surging phenomenon shown in FIG. 5. [Figure 7] FIG. 2 is a diagram for explaining a first example of vehicle control according to the present embodiment. [Figure 8] FIG. 11 is a diagram for explaining a second example of vehicle control according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and their description will not be repeated.

[0020] FIG. 1 is a diagram showing an overall configuration of a battery cooling system 1 according to the present embodiment. Referring to FIG. 1, the battery cooling system 1 is mounted on a vehicle. The vehicle is, for example, an xEV (electric vehicle) configured to be able to run using power from an on-board battery (battery module 2). Examples of xEVs include a BEV (electric vehicle), a HEV (hybrid vehicle), a PHEV (plug-in hybrid vehicle), a FCEV (fuel cell vehicle), and a range extender EV. The battery cooling system 1 includes a plurality of battery modules 2, a refrigeration cycle 10, and a control device 100. The battery cooling system 1 cools the plurality of battery modules 2 using the refrigeration cycle 10. Each battery module 2 is formed by connecting a plurality of battery cells (not shown). The plurality of battery modules 2 are packaged as one battery pack, for example, by being housed in a housing (not shown).

[0021] The refrigeration cycle 10 forms a circuit through which a refrigerant circulates. The refrigeration cycle 10 includes a compressor 11, a condenser 12, a fan 13, a plurality of pressure reducers 14, a plurality of evaporators 15, flow paths 31, 32, and 35, a plurality of branch flow paths 33, and a plurality of branch flow paths 34.

[0022] The compressor 11 is a speed type compressor that compresses the refrigerant gas sucked from the flow path 35 and discharges it to the flow path 31. The flow path 31 connects the discharge port of the compressor 11 to the inlet of the condenser 12. The condenser 12 exchanges heat between the refrigerant supplied from the compressor 11 and flowing inside the condenser 12 and a fluid (e.g., outside air) present around the condenser 12. The fan 13 is disposed at a position where the condenser 12 can be cooled. The fan 13 functions as a cooling fan that air-cools the condenser 12. The fan 13 may cool the condenser 12 by sending air outside the vehicle cabin to the condenser 12.

[0023] The flow path 32 connects the outlet of the condenser 12 and the connection point N1. The flow path 32 branches into a plurality of branch flow paths 33 at the connection point N1. The plurality of branch flow paths 33 connect the connection point N1 and the inlets of the plurality of evaporators 15, respectively. A plurality of pressure reducers 14 are provided on the plurality of branch flow paths 33, respectively. Each of the plurality of pressure reducers 14 is formed of, for example, an inexpensive fixed orifice. Each of the plurality of pressure reducers 14 may be an expansion valve (throttle valve).

[0024] Fig. 2 is a diagram showing an example of the arrangement of the branch flow paths 33 and the pressure reducers 14. As shown in Fig. 2, a main pipe 33m that connects the connection point N1 to each branch flow path 33 is arranged between the connection point N1 and each branch flow path 33. The refrigerant from the flow path 32 is supplied to the main pipe 33m at the connection point N1, and is distributed from the main pipe 33m to each branch flow path 33. The flow path 32, the main pipe 33m, and the branch flow paths 33 may correspond to the "second flow path" of the present disclosure.

[0025] In this embodiment, a pressure sensor 50 and a temperature sensor 60 are provided near a branch flow path (the rightmost branch flow path in FIG. 2) 33a in which a pressure reducer 14a (the rightmost pressure reducer in FIG. 2) having the longest flow path length from a connection point N1 among the multiple pressure reducers 14 is arranged. The pressure sensor 50 detects a refrigerant pressure Pa in the multiple branch flow paths 33 near the branch flow path 33a. The temperature sensor 60 detects a refrigerant temperature Ta in the multiple branch flow paths 33 near the branch flow path 33a. Each of the pressure sensor 50 and the temperature sensor 60 outputs a detection result to the control device 100.

[0026] Referring again to FIG. 1, the multiple evaporators 15 are disposed corresponding to the multiple battery modules 2, respectively, and perform heat exchange between the refrigerant flowing therethrough and the multiple battery modules 2, respectively. The multiple evaporators 15 have the same shape. Therefore, the multiple evaporators 15 have the same flow path cross-sectional area. The multiple branch flow paths 34 connect the outlets of the multiple evaporators 15 to a connection point N2, respectively. The multiple branch flow paths 34 merge into a flow path 35 at the connection point N2. The flow path 35 connects the connection point N2 to the suction port of the compressor 11.

[0027] A pressure sensor 71 (first pressure sensor) is provided on the suction side (e.g., near the suction port) of the compressor 11. The pressure sensor 71 detects the pressure Pb (suction pressure) of the refrigerant gas on the suction side of the compressor 11. A pressure sensor 72 (second pressure sensor) and a flow rate sensor 80 are provided on the discharge side (e.g., near the discharge port) of the compressor 11. The pressure sensor 72 detects the pressure Pc (discharge pressure) of the refrigerant gas on the discharge side of the compressor 11. The flow rate sensor 80 detects the flow rate Gc of the refrigerant gas flowing through the compressor 11 toward the condenser 12. Each of the pressure sensors 71, 72 and the flow rate sensor 80 outputs the detection results to the control device 100.

[0028] The control device 100 is configured to control the battery cooling system 1. Although details will be described later, the control device 100 controls the rotation speeds of the compressor 11 and the fan 13 based on detection signals input from the pressure sensor 50, the temperature sensor 60, the pressure sensors 71 and 72, and the flow rate sensor 80. The control device 100 may also perform driving control of a vehicle equipped with the battery cooling system 1 (see, for example, Figs. 7 and 8). The control device 100 includes a processor 110, a RAM (Random Access Memory) 120, and a storage device 130. An example of the processor 110 is a CPU (Central Processing Unit). The storage device 130 is configured to be able to save stored information. In this embodiment, the processor 110 executes a program stored in the storage device 130 to execute various controls (for example, controls shown in Figs. 3 to 6 described later). However, these processes may be executed only by hardware (electronic circuits) without using software. The number of processors included in the control device 100 is arbitrary, and may be one or more.

[0029] In the operating state of the refrigeration cycle 10, a high-temperature, high-pressure gas refrigerant compressed by the compressor 11 is sent to the condenser 12 and condensed by the condenser 12. This liquefies the refrigerant. The high-temperature, high-pressure liquid refrigerant condensed by the condenser 12 is supplied to a flow path 32 and distributed from the flow path 32 to a plurality of branch flow paths 33. The refrigerant distributed to the plurality of branch flow paths 33 is depressurized by a plurality of pressure reducers 14 and then sent to a plurality of evaporators 15.

[0030] The low-pressure refrigerant sent to the multiple evaporators 15 exchanges heat with the multiple battery modules 2 in the multiple evaporators 15 and evaporates (gasifies) to become a low-pressure gas refrigerant. This cools the multiple battery modules 2. The low-pressure gas refrigerant evaporated in the multiple evaporators 15 joins together at the connection point N2, passes through the flow path 35, and is sucked into the compressor 11 again.

[0031] During the above-described cooling operation, in order to uniformly cool the multiple battery modules 2, it is desirable to distribute the same amount of refrigerant to each of the multiple branch flow paths 33. To achieve this, it is desirable to maintain the refrigerant in the main pipe 33m in a liquid state (subcooled state). In this embodiment, it is determined to be an abnormality (subcooled abnormality) when the refrigerant is no longer in a liquid state in the region downstream of the condenser 12 and upstream of the pressure reducer 14 of the refrigeration cycle 10 (i.e., the region upstream of the pressure reducer 14 in the second flow path).

[0032] However, depending on the temperature of each battery module 2 and the outside air temperature around the condenser 12, the refrigerant in the main pipe 33m may not necessarily become liquid. If the rotation speed of the compressor 11 is set to an excessively high value as a countermeasure, there is a concern that the power consumption of the compressor 11 will be unnecessarily large. In addition, depending on the operating state of the compressor 11, a surging phenomenon of the compressor 11 (i.e., the compressor 11 cannot operate normally) may occur. If the vehicle continues to run in a state where a surging phenomenon occurs, the NV (noise and vibration) performance of the vehicle will deteriorate. In addition, since the surging phenomenon is likely to cause a system failure, the surging phenomenon is more likely to cause a serious problem in the system than the subcooling abnormality.

[0033] Therefore, the control device 100 according to this embodiment is adapted to suitably suppress the subcooling abnormality and the surging phenomenon by executing the controls shown in Figures 3 to 6, which will be described below. In more detail, when the control device 100 can simultaneously suppress both the subcooling abnormality and the surging phenomenon, it suppresses both, but when it can suppress only one of them, it preferentially suppresses the surging phenomenon.

[0034] In the following, each step in the flowchart will simply be denoted as "S". The rotation speed command value from the control device 100 to the compressor 11 will be denoted as "Ncomp". Adjusting Ncomp to the acceleration side will be referred to as "Ncomp increase", and adjusting Ncomp to the deceleration side will be referred to as "Ncomp decrease". The rotation speed command value from the control device 100 to the fan 13 will be denoted as "Nfan". Adjusting Nfan to the acceleration side will be referred to as "Nfan increase", and adjusting Nfan to the deceleration side will be referred to as "Nfan decrease".

[0035] When the rotation speed of the compressor 11 is within a first operating range from an Ncomp lower limit (compressor rotation lower limit) to an Ncomp upper limit (compressor rotation upper limit), the normal operation of the compressor 11 is guaranteed by the manufacturer. When the rotation speed of the compressor 11 deviates from the first operating range, the operation of the compressor 11 may become unstable or deterioration of the compressor 11 may be accelerated. The control device 100 basically controls the rotation speed of the compressor 11 within the first operating range. Also, when the rotation speed of the fan 13 is within a second operating range below an Nfan upper limit (fan rotation upper limit), the normal operation of the fan 13 is guaranteed by the manufacturer. When the rotation speed of the fan 13 deviates from the second operating range, the operation of the fan 13 may become unstable or deterioration of the fan 13 may be accelerated. The control device 100 basically controls the rotation speed of the fan 13 within the second operating range.

[0036] Fig. 3 is a flowchart showing an example of a processing procedure of the control device 100. The processing shown in this flowchart is repeatedly executed by the control device 100, for example, at a predetermined cycle. However, the present invention is not limited to this, and the control device 100 may execute the processing flow shown in Fig. 3 only when a predetermined start condition is satisfied. The start condition may be set so as to be satisfied only in a situation in which at least one of a subcooling anomaly and a surging phenomenon may occur.

[0037] 3, in S1, the control device 100 determines whether the current value of Nfan is less than the Nfan upper limit value. Since the rotation speed of the fan 13 is controlled according to Nfan (command value), the rotation speed of the fan 13 corresponds to Nfan. The current value of Nfan roughly coincides with the current rotation speed of the fan 13.

[0038] When the current value of Nfan is less than the Nfan upper limit value (YES in S1), the control device 100 executes a first judgment in S21. The first judgment includes a subcool judgment and a surge judgment. The subcool judgment is a judgment as to whether or not the above-mentioned subcool abnormality occurs. The control device 100 executes the subcool judgment based on the detection result of the first detection means that detects the state of the refrigerant upstream of the pressure reducer 14 in the second flow path. In this embodiment, the pressure sensor 50 and the temperature sensor 60 function as the first detection means. The surge judgment is a judgment as to whether or not the surging phenomenon of the compressor 11 occurs. The control device 100 executes the surge judgment based on the detection result of the second detection means that detects the state of the compressor 11. In this embodiment, the pressure sensors 71, 72 and the flow rate sensor 80 function as the second detection means. FIG. 4 is a flowchart showing the details of the process related to the first judgment (S21).

[0039] Referring to FIG. 4, S111 to S113 and S121 to S129 are a process flow related to the subcooling judgment. In S111, the control device 100 acquires the refrigerant pressure Pa detected by the pressure sensor 50. In the following S112, the control device 100 calculates the saturation temperature of the main pipe 33m in the vicinity of the branch flow path 33a in the plurality of branch flow paths 33 based on the refrigerant pressure Pa. For example, correspondence information (e.g., a map or a formula) that specifies the correspondence relationship between the refrigerant pressure and the saturation temperature may be stored in advance in the storage device 130. The control device 100 may calculate the saturation temperature corresponding to the refrigerant pressure Pa by referring to the correspondence information. Next, in S113, the control device 100 acquires the refrigerant temperature Ta detected by the temperature sensor 60, and in the following S121, based on a value (temperature difference) obtained by subtracting the refrigerant temperature Ta from the saturation temperature, judges which of the following first to third states the state of the refrigerant corresponds to.

[0040] The first state is a refrigerant state in which a subcooling abnormality occurs. The second state is a refrigerant state in which a subcooling abnormality is unlikely to occur. The third state is a refrigerant state that is neither the first state nor the second state. A refrigerant state that is determined to correspond to the second state or the third state means that a subcooling abnormality is determined not to occur. In this embodiment, if the above temperature difference (saturation temperature - Ta) is within the appropriate range, it is determined to be the third state (appropriate liquefaction state), if it is smaller than the appropriate range, it is determined to be the first state (insufficient liquefaction state), and if it is larger than the appropriate range, it is determined to be the second state (excessive liquefaction state). The closer the refrigerant temperature Ta is to the saturation temperature, the more likely a subcooling abnormality is to occur.

[0041] The appropriate range is, for example, a range between the first threshold and the second threshold. In this embodiment, when the temperature difference (saturation temperature - Ta) is less than the first threshold, the control device 100 determines in S122 that the state of the refrigerant corresponds to the "first state", and in the subsequent S123, determines "A13" as the method of suppressing the subcooling abnormality. The determination of A13 means that the adjustment according to the determination result of the subcooling abnormality is an increase in Nfan. By increasing the rotation speed of the fan 13 without changing the rotation speed of the compressor 11, the subcooling abnormality is less likely to occur. The degree (adjustment amount) of the increase in Nfan according to the determination of A13 may be a predetermined fixed value, or may be variable according to a predetermined parameter (for example, the difference between the saturation temperature and the refrigerant temperature Ta, or the difference between the current Nfan value and the upper limit Nfan value).

[0042] If the temperature difference (saturation temperature-Ta) exceeds the second threshold, the control device 100 determines in S124 that the state of the refrigerant corresponds to the "second state", and the process proceeds to S125. In S125, the control device 100 determines whether the current value of Ncomp is greater than the lower limit value of Ncomp. Since the rotation speed of the compressor 11 is controlled according to Ncomp (command value), the rotation speed of the compressor 11 corresponds to Ncomp. The current value of Ncomp roughly coincides with the current rotation speed of the compressor 11.

[0043] If the current value of Ncomp is greater than the Ncomp lower limit value (YES in S125), the control device 100 makes a judgment of "A12" in the subsequent S126 regarding the method of suppressing the subcooling abnormality. The judgment of A12 means that the adjustment according to the judgment result of the subcooling abnormality is a reduction in Ncomp. The lower the rotation speed of the compressor 11, the less energy is consumed by the compressor 11. The degree (adjustment amount) of the reduction in Ncomp according to the judgment of A12 may be a predetermined fixed value, or may be variable according to a predetermined parameter (for example, the difference between the saturation temperature and the refrigerant temperature Ta, or the difference between the current Ncomp value and the Ncomp lower limit value).

[0044] If the current value of Ncomp is equal to or less than the Ncomp lower limit value (NO in S125), the control device 100 judges "A11" in the subsequent S127 regarding the method of suppressing the subcooling abnormality. The judgment of A11 means that the adjustment according to the judgment result of the subcooling abnormality is a reduction in Nfan. The lower the rotation speed of the fan 13, the less energy is consumed by the fan 13. The degree of reduction in Nfan according to the judgment of A11 (adjustment amount) may be a predetermined fixed value, or may be variable according to a predetermined parameter (for example, the difference between the saturation temperature and the refrigerant temperature Ta, or the difference between the current Nfan value and the Nfan lower limit value).

[0045] In this embodiment, the energy consumed to drive the compressor 11 that draws in and discharges the refrigerant is greater than the energy consumed to drive the fan 13 that cools the condenser 12. Therefore, the amount of energy consumption reduced is greater by reducing Ncomp than by reducing Nfan. The compressor 11 and the fan 13 may be driven by power supplied from the battery module 2, or may be driven by power supplied from another vehicle-mounted battery (e.g., an auxiliary battery).

[0046] If the temperature difference (saturation temperature - Ta) is equal to or greater than the first threshold and equal to or less than the second threshold, the control device 100 determines in S128 that the state of the refrigerant corresponds to the "third state", and then in the subsequent S129 determines "A14" as the method of suppressing the subcooling abnormality. The determination of A14 means that the adjustment according to the determination result of the subcooling abnormality is to leave both Nfan and Ncomp unchanged (no adjustment required). When any of the determinations A11 to A14 is made, the process flow for the subcooling determination ends.

[0047] S131 to S133 and S141 to S145 are processing flows related to surge determination. In S131, the control device 100 acquires the pressures Pb, Pc and the flow rate Gc detected by the pressure sensors 71, 72 and the flow rate sensor 80, respectively. In the following S132, the control device 100 converts the flow rate Gc into a corrected flow rate (amount of suction refrigerant) indicating the operating point of the compressor 11. The control device 100 may convert the flow rate Gc into the corrected flow rate by multiplying the flow rate Gc by a predetermined correction coefficient. The control device 100 may also convert the flow rate Gc into the corrected flow rate based on the refrigerant temperature.

[0048] Next, in S133, the control device 100 specifies an operating point (Comp operating point) of the compressor 11 using the corrected flow rate according to the flow rate Gc and the pressure ratio according to the pressures Pb and Pc, and in the following S141, it is determined whether the specified Comp operating point is included in a predetermined surging region. The operating point of the compressor 11 in this embodiment is an operating state of the compressor 11 that is determined by the corrected flow rate (amount of refrigerant sucked in) of the compressor 11 and the pressure ratio (=Pc / Pb). The pressure ratio is the ratio of the pressure Pc (discharge pressure) to the pressure Pb (suction pressure). A map (see, for example, FIG. 6) showing the surge characteristics of the compressor 11 may be stored in advance in the storage device 130. A surge line showing the surging region (i.e., an operating region where the surging phenomenon is likely to occur in the compressor 11) may be set on the map. The surge line is a line showing the boundary between the inside and outside of the surging region, and may be set in consideration of a margin. Furthermore, if the flow rate Gc indicates the operating point of the compressor 11 with high accuracy, the conversion in S132 may be omitted.

[0049] When the operating point of the compressor 11 is included in the surging region (YES in S141), the control device 100 determines in S142 that the surging phenomenon of the compressor 11 occurs (i.e., the compressor 11 is in a surging state), and in the following S143, determines "B11" as the method of suppressing the surging phenomenon. The determination of B11 means that the adjustment according to the determination result of the surging phenomenon is an increase in Nfan. By increasing the rotation speed of the fan 13 without changing the rotation speed of the compressor 11, the surging phenomenon becomes less likely to occur. The degree (adjustment amount) of the increase in Nfan according to the determination of B11 may be a predetermined fixed value, or may be variable according to a predetermined parameter (for example, the Comp operating point, or the difference between the Nfan current value and the Nfan upper limit value).

[0050] If the operating point of the compressor 11 is not included in the surging region (NO in S141), the control device 100 determines in S144 that the surging phenomenon of the compressor 11 does not occur (i.e., the compressor 11 is in a non-surge state), and subsequently determines "B12" regarding the method of suppressing the surging phenomenon in S145. The determination of B12 means that the adjustment according to the determination result of the surging phenomenon is to leave both Nfan and Ncomp unchanged (no adjustment required). When either the determination of B11 or B12 is made, the processing flow regarding the surge determination ends.

[0051] When the process flow for the first judgment (subcool judgment and surge judgment) shown in Fig. 4 is executed, the process returns to the process flow of Fig. 3 and proceeds to S22. In S22, the control device 100 determines an adjustment amount for suppressing the occurrence of an abnormality based on the result of the first judgment and the first judgment matrix shown in Fig. 3, and then outputs the determined adjustment amount in S40. Then, the rotation speeds of the compressor 11 and the fan 13 are controlled by commands reflecting the determined adjustment amount (see Figs. 7 and 8 described later for details).

[0052] Specifically, when the rotation speed of the fan 13 is less than the upper limit (YES in S1), the control device 100 uses, for example, a first judgment matrix stored in the storage device 130 to determine the adjustment amount as described below. When it is determined that the surging phenomenon does not occur (B12) but the subcooling abnormality occurs (A13), the control device 100 determines to adjust the rotation speed of the fan 13 so as to suppress the subcooling abnormality (increase Nfan) and not to adjust the rotation speed of the compressor 11. In detail, the control device 100 adjusts the rotation speed of the fan 13 to be accelerated by the adjustment amount according to the A13 judgment. When the rotation speed of the compressor 11 is greater than the lower limit, when it is determined that the surging phenomenon does not occur (B12) and the state of the refrigerant is the second state (A12), the control device 100 adjusts the rotation speed of the compressor 11 to be decelerated by the adjustment amount according to the A12 judgment (decrease Ncomp) and not to adjust the rotation speed of the fan 13. When the rotation speed of the compressor 11 is not greater than the lower limit, if it is determined that the surging phenomenon does not occur (B12) and the state of the refrigerant is in the second state (A11), the control device 100 adjusts the rotation speed of the fan 13 to be decelerated (Nfan decrease) by an adjustment amount according to the A11 judgment, and determines not to adjust the rotation speed of the compressor 11. If it is determined that the surging phenomenon does not occur (B12) and the state of the refrigerant is in the third state (A14), the control device 100 determines not to change both the rotation speed of the fan 13 and the rotation speed of the compressor 11 (no adjustment). If it is determined that the surging phenomenon occurs (B11), the control device 100 adjusts the rotation speed of the fan 13 so as to suppress the surging phenomenon, and does not adjust the rotation speed of the compressor 11. In more detail, the control device 100 adjusts the rotation speed of the fan 13 to be accelerated by an adjustment amount according to the B11 judgment.

[0053] When the current value of Nfan is equal to or greater than the Nfan upper limit (NO in S1), the control device 100 executes a second determination in S31. The second determination includes a subcooling determination and a surge determination. Fig. 5 is a flowchart showing the details of the process related to the second determination (S31).

[0054] With reference to Fig. 5, S211 to S213 and S221 to S229 are a process flow relating to the sub-cooling judgment. The processes of S211 to S213 and S221 to S229 in Fig. 5 are basically similar to the processes of S111 to S113 and S121 to S129 in Fig. 4 described above, respectively, and therefore overlapping descriptions will not be repeated. In the process flow relating to the sub-cooling judgment shown in Fig. 5, instead of S123 (A13 judgment), S126 (A12 judgment), S127 (A11 judgment), and S129 (A14 judgment) in Fig. 4, S223 (A23 judgment), S226 (A21 judgment), S227 (A22 judgment), and S229 (A24 judgment), respectively, are adopted.

[0055] In S223, the control device 100 judges "A23" regarding the method of suppressing the subcooling abnormality. The judgment of A23 means that the adjustment according to the judgment result of the subcooling abnormality is to increase Ncomp. By increasing the rotation speed of the compressor 11 without changing the rotation speed of the fan 13, the subcooling abnormality becomes less likely to occur. The degree of increase in Ncomp (adjustment amount) according to the judgment of A23 may be a predetermined fixed value, or may be variable according to a predetermined parameter (for example, the difference between the saturation temperature and the refrigerant temperature Ta, or the difference between the current Ncomp value and the Ncomp upper limit value).

[0056] The A21 judgment in S226 is the same as the A12 judgment in S126 in FIG. 4. That is, the A21 judgment indicates "reduced Ncomp." The A22 judgment in S227 is the same as the A11 judgment in S127 in FIG. 4. The A22 judgment indicates "reduced Nfan." The A24 judgment in S229 is the same as the A14 judgment in S129 in FIG. 4. That is, the A24 judgment indicates "no adjustment required." When any of the judgments A21 to A24 is made, the process flow for the subcooling judgment ends.

[0057] S231 to S233 and S241 to S244 are processing flows relating to surge determination. The processes of S231 to S233 and S241 are basically similar to the processes of S131 to S133 and S141 in Fig. 4, respectively, and therefore overlapping descriptions will not be repeated.

[0058] When the operating point of the compressor 11 is included in the surging region (YES in S241), the control device 100 executes a process for avoiding the surging phenomenon in S242. Fig. 6 is a flowchart showing the details of the process for avoiding the surging phenomenon (S242).

[0059] Referring to FIG. 6, in S301, the control device 100 determines whether the adjustment direction of Ncomp to move the operating point (Comp operating point) of the compressor 11 out of the surging region is to increase or decrease, based on a map M1 (a map stored in the memory device 130) indicating the surge characteristics of the compressor 11, the current value of Ncomp, the pressure Pb (suction pressure), the pressure Pc (discharge pressure), and the flow rate Gc.

[0060] When it is determined in S301 that the adjustment direction of Ncomp for avoiding the surging phenomenon is a decrease (deceleration side), the control device 100 determines in S302 whether the current value of Ncomp is greater than the lower limit value of Ncomp. When the current value of Ncomp is greater than the lower limit value of Ncomp (YES in S302), the control device 100 determines "B21" in the next S303 regarding the suppression method of the surging phenomenon. The determination of B21 means that the adjustment according to the determination result of the surging phenomenon is a decrease in Ncomp. The control device 100 calculates the degree of decrease in Ncomp according to the determination of B21 (adjustment amount for avoiding the surging phenomenon) based on the map M1, the current value of Ncomp, the pressures Pb, Pc, and the flow rate Gc. On the other hand, when the current value of Ncomp is equal to or less than the lower limit value of Ncomp (NO in S302), the control device 100 generates a signal (load adjustment request signal) requesting adjustment of the battery load to avoid the surging phenomenon in the next S304. The load adjustment request signal is a signal that requests to avoid the surge phenomenon by control outside the refrigeration cycle 10. The load adjustment request signal may request, for example, to limit at least one of the charging and discharging of the battery module 2.

[0061] When it is determined in S301 that the adjustment direction of Ncomp for avoiding the surging phenomenon is an increase (acceleration side), the control device 100 determines in S305 whether the current value of Ncomp is less than the Ncomp upper limit value. When the current value of Ncomp is less than the Ncomp upper limit value (YES in S305), the control device 100 determines "B22" in the next S306 regarding the suppression method of the surging phenomenon. The determination of B22 means that the adjustment according to the determination result of the surging phenomenon is an increase in Ncomp. The control device 100 calculates the degree of increase in Ncomp according to the determination of B22 (adjustment amount for avoiding the surging phenomenon) based on the map M1, the current value of Ncomp, the pressures Pb, Pc, and the flow rate Gc. On the other hand, when the current value of Ncomp is equal to or greater than the Ncomp upper limit value (NO in S305), the control device 100 generates a signal (load adjustment request signal) requesting adjustment of the battery load to avoid the surging phenomenon in the next S307.

[0062] Referring again to FIG. 5, if the operating point of the compressor 11 is not included in the surging region (NO in 241), the control device 100 determines in S243 that the surging phenomenon of the compressor 11 is not occurring, and subsequently determines "B23" in relation to the method of suppressing the surging phenomenon in S244. The determination of B23 means that the adjustment according to the determination result of the surging phenomenon is not to change either Nfan or Ncomp (no adjustment required). When any of the determinations of B21 to B23 is made, the process flow for surge determination ends. Also, when a load adjustment request signal (S304, S307 in FIG. 6) is generated, the process flow for surge determination ends.

[0063] When the process flow for the second judgment (subcooling judgment and surge judgment) shown in Fig. 5 is executed, the process returns to the process flow in Fig. 3 and proceeds to S32. In S32, the control device 100 determines an adjustment amount for suppressing the occurrence of an abnormality based on the result of the second judgment and the second judgment matrix shown in Fig. 3, and then outputs the determined adjustment amount in S40.

[0064] Specifically, when the rotation speed of the fan 13 is equal to or higher than the upper limit (NO in S1), the control device 100 determines the adjustment amount as described below, for example, using a second judgment matrix stored in the storage device 130. When it is determined that the surging phenomenon does not occur (B23) but the subcooling abnormality occurs (A23), the control device 100 determines to adjust the rotation speed of the compressor 11 (increase Ncomp) so as to suppress the subcooling abnormality, and not to adjust the rotation speed of the fan 13. In detail, the control device 100 adjusts the rotation speed of the compressor 11 to be accelerated by the adjustment amount according to the judgment of A23. When the rotation speed of the compressor 11 is higher than the lower limit, when it is determined that the surging phenomenon does not occur (B23) and the state of the refrigerant is the second state (A21), the control device 100 determines to adjust the rotation speed of the compressor 11 to be decelerated by the adjustment amount according to the judgment of A21 (decrease Ncomp), and not to adjust the rotation speed of the fan 13. When the rotation speed of the compressor 11 is not greater than the lower limit, if the surging phenomenon does not occur (B23) and if it is determined that the state of the refrigerant is in the second state (A22), the control device 100 adjusts the rotation speed of the fan 13 to be decelerated (Nfan decrease) by an adjustment amount according to the A22 judgment, and determines not to adjust the rotation speed of the compressor 11. When the surging phenomenon does not occur (B23) and if it is determined that the state of the refrigerant is in the third state (A24), the control device 100 determines not to change both the rotation speed of the fan 13 and the rotation speed of the compressor 11 (no adjustment). When it is determined that the surging phenomenon occurs when the rotation speed of the compressor 11 is greater than the lower limit and less than the upper limit, the control device 100 adjusts the rotation speed of the compressor 11 to be decelerated (Ncomp decrease) by an adjustment amount according to the B21 judgment, or adjusts the rotation speed of the compressor 11 to be accelerated (Ncomp increase) by an adjustment amount according to the B22 judgment. This suppresses the surging phenomenon.

[0065] Furthermore, if a load adjustment request signal (see FIG. 6) is generated in S31, the adjustment amount is determined to be "0 (no adjustment)" in S32, and the control device 100 outputs the load adjustment request signal in the following S40.

[0066] Hereinafter, an example of vehicle control using the adjustment amount or the load adjustment request signal obtained by the process shown in FIG. 3 will be described with reference to FIG. 7 and FIG. 8. As shown in FIG. 7 and FIG. 8, the vehicle according to this example further includes a PCU (Power Control Unit) 3, a MG (Motor Generator) 4, and drive wheels W. The PCU 3 includes electronic circuits such as an inverter and a DC / DC converter, and is located between the battery module 2 and the MG 4. The PCU 3 drives the MG 4 using power supplied from the battery module 2 (for example, a battery pack formed by a plurality of battery modules 2). The MG 4 functions as a motor for driving the vehicle. The MG 4 in the power running state is driven by the PCU 3 to rotate the drive wheels W. The MG 4 also performs regenerative power generation, for example, when braking the vehicle. The MG 4 in the power generation state outputs the generated power to the battery module 2. The number of motors and drive wheels is arbitrary, and may be one or more.

[0067] Fig. 7 is a diagram for explaining a first example of vehicle control according to the present embodiment. The control device 100A shown in Fig. 7 corresponds to the above-mentioned control device 100 (Fig. 1) and executes the processes shown in Figs. 3 to 6. Furthermore, the control device 100A includes adder circuits 141 and 142.

[0068] The control device 100A repeatedly executes the process shown in FIG. 3 at a predetermined cycle. In the current processing routine, Nfan and Ncomp (previous values) determined in the previous processing routine correspond to the current values ​​of Nfan and Ncomp, respectively. In S40 in FIG. 3, the determined adjustment amounts of Nfan and Ncomp are output to the adder circuits 141 and 142, respectively. The adder circuits 141 and 142 add the input adjustment amounts of Nfan and Ncomp to the previous values ​​of Nfan and Ncomp, respectively. The adjustment amount on the acceleration side is expressed as a positive value, the adjustment amount on the deceleration side is expressed as a negative value, and no adjustment is expressed as a value "0". In this embodiment, the adjustment amount of at least one of Nfan and Ncomp becomes "0". The control device 100A determines the Nfan and Ncomp after addition output from the adder circuits 141 and 142 as Nfan and Ncomp (current values), respectively, and controls the fan 13 and the compressor 11 according to the determined Nfan and Ncomp.

[0069] 3 is output to the PCU 3 in S40. For example, the control device 100A limits the exchange of power between the battery module 2 and the MG 4 by sending the load adjustment request signal to the PCU 3. The load adjustment request signal may lower the upper limit of the power output from the battery module 2 to the MG 4. The load adjustment request signal may also lower the upper limit of the power input from the MG 4 to the battery module 2.

[0070] FIG. 8 is a diagram for explaining a second example of vehicle control according to the present embodiment. The control device 100B shown in FIG. 8 corresponds to the above-mentioned control device 100 (FIG. 1), and executes the processes shown in FIGS. 3 to 6. Furthermore, the storage device of the control device 100B stores a map M2 (correspondence information) that defines the correspondence between the battery state and each of the target Nfan and the target Ncomp. The battery state includes the temperature of the multiple battery modules 2. The battery state may include the current and voltage instead of or in addition to the temperature.

[0071] The control device 100B refers to the map M2 to obtain the target Nfan and the target Ncomp corresponding to the current battery state. The control device 100B then executes the process shown in FIG. 3 and adjusts the target Nfan and the target Ncomp according to the adjustment amount output in S40. The control device 100B determines the adjusted Nfan and Ncomp as Nfan and Ncomp (current values), respectively. When the adjustment amount of both Nfan and Ncomp is "0 (no adjustment)", the target Nfan and the target Ncomp are determined as Nfan and Ncomp (current values) as they are. Then, the control device 100B controls the fan 13 and the compressor 11 according to the determined Nfan and Ncomp, respectively. In addition, when a load adjustment request signal is generated in S31 of FIG. 3, the control device 100B restricts the exchange of power between the battery module 2 and the MG4 by sending the load adjustment request signal to the PCU 3, similar to the above-mentioned control device 100A.

[0072] In the above, the PCU is shown as an example of the output destination of the load adjustment request signal, but the output destination of the load adjustment request signal is not limited to the PCU. For example, the driving load may be instructed to the PCU via a vehicle ECU or the like. Alternatively, output adjustment may be performed between the vehicle ECU and the charger during quick charging or the like. The output destination of the load adjustment request signal can be set arbitrarily.

[0073] As described above, the control device according to this embodiment (control devices 100, 100A, 100B) determines whether or not a subcooling abnormality occurs in which the refrigerant is no longer in a liquid state upstream of pressure reducer 14 in the second flow path based on the detection result of the first detection means (see FIGS. 3 to 5), determines whether or not a surging phenomenon occurs in compressor 11 based on the detection result of the second detection means (see FIGS. 3 to 6), and, if it is determined that a surging phenomenon will occur, adjusts either the rotation speed of fan 13 or the rotation speed of compressor 11 so as to suppress the surging phenomenon. When it is determined that a surging phenomenon will not occur but a subcooling anomaly will occur, the rotation speed of the fan 13 or the rotation speed of the compressor 11 is adjusted so that the subcooling anomaly is suppressed (for example, an adjustment corresponding to the A13 judgment and the B12 judgment in the first judgment matrix, and an adjustment corresponding to the A23 judgment and the B23 judgment in the second judgment matrix).

[0074] In the above configuration, when it is determined that the surging phenomenon will not occur (i.e., the compressor 11 can operate normally) and when it is determined that the subcooling abnormality will occur (i.e., the refrigerant will not be in a liquid state upstream of the pressure reducer 14 in the second flow path), one of the rotation speed of the fan 13 and the rotation speed of the compressor 11 is adjusted so that the subcooling abnormality is suppressed. This makes it difficult for the subcooling abnormality to occur. On the other hand, when it is determined that the surging phenomenon will occur, regardless of the determination result of the subcooling abnormality, one of the rotation speed of the fan 13 and the rotation speed of the compressor 11 is adjusted so that at least the surging phenomenon is suppressed. This makes it difficult for the surging phenomenon to occur. According to the above configuration, the control for suppressing the surging phenomenon is preferentially executed, thereby suppressing the promotion of the surging phenomenon due to the control for suppressing the subcooling abnormality.

[0075] If both the rotation speed of the compressor 11 and the rotation speed of the fan 13 are changed at the same time, these changes will affect each other, making it difficult to obtain control parameters for suppressing the occurrence of abnormalities (subcool abnormalities or surging phenomenon). If the correct control parameters are not obtained, there is a possibility that the occurrence of abnormalities will not be avoided. Therefore, in the above configuration, one of the rotation speed of the fan 13 and the rotation speed of the compressor 11 is adjusted. This makes it possible to obtain the adjustment direction and adjustment amount of the rotation speed of the compressor 11 to suppress the occurrence of abnormalities on the premise that the rotation speed of the fan 13 does not change. Also, it makes it possible to obtain the adjustment direction and adjustment amount of the rotation speed of the fan 13 to suppress the occurrence of abnormalities on the premise that the rotation speed of the compressor 11 does not change. Therefore, it becomes easier to accurately obtain control parameters for suppressing the occurrence of abnormalities. This makes it possible to more reliably avoid the occurrence of abnormalities (especially the surging phenomenon). However, if the adjustment is insufficient by changing only one of the rotation speeds of the compressor 11 and the fan 13, both may be changed.

[0076] The control device according to the present embodiment calculates the saturation temperature of the refrigerant upstream of the pressure reducer 14 in the second flow path based on the pressure of the refrigerant detected by the pressure sensor 50 (first detection means) (S112 in FIG. 4 and S212 in FIG. 5), and determines whether or not a subcooling abnormality occurs based on the saturation temperature and the temperature of the refrigerant detected by the temperature sensor 60 (first detection means) (S113, S121 in FIG. 4 and S213, S221 in FIG. 5). This makes it easier to appropriately determine whether or not a subcooling abnormality occurs. In addition, the control device according to the present embodiment identifies the operating point of the compressor 11 using the suction pressure, discharge pressure, and flow rate detected by the pressure sensors 71 and 72 and the flow rate sensor 80 (second detection means), and determines whether or not a surging phenomenon occurs based on whether or not the identified operating point is included in a predetermined surging region (S131 to S133, S141 in FIG. 4 and S231 to S233, S241 in FIG. 5). This makes it easier to appropriately determine whether or not the surging phenomenon occurs.

[0077] The batteries cooled by the battery cooling system are not limited to batteries installed in xEVs, but may also be batteries used in vehicles other than automobiles (railroad cars, ships, airplanes, etc.), unmanned mobile objects (automated guided vehicles (AGVs), agricultural machinery, walking robots, drones, robot cleaners, space probes, etc.), or stationary energy storage systems.

[0078] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present disclosure is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0079] 1 battery cooling system, 2 battery module, 3 PCU, 4 MG, 10 refrigeration cycle, 11 compressor, 12 condenser, 13 fan, 14 pressure reducer, 15 evaporator, 31, 32, 35 flow path, 33, 33a, 34 branch flow path, 50, 71, 72 pressure sensor, 60 temperature sensor, 80 flow rate sensor, 100, 100A, 100B control device.

Claims

1. A battery cooling system, comprising: The present invention includes a refrigeration cycle that forms a circuit through which a refrigerant circulates, and a control device. The refrigeration cycle includes: A compressor, a condenser, and a fan for cooling the condenser; A plurality of evaporators arranged corresponding to the plurality of batteries, respectively; a first flow path connected to a discharge port of the compressor and one end of the condenser; a second flow path connecting the other end of the condenser and one ends of the plurality of evaporators; a third flow path connecting the other ends of the plurality of evaporators and a suction port of the compressor; The compressor is a speed type compressor, the second flow path includes a plurality of branch flow paths connected to one ends of the plurality of evaporators, The battery cooling system includes: A plurality of pressure reducers respectively disposed in the plurality of branch flow paths; a first detection means for detecting a state of the refrigerant upstream of the pressure reducer in the second flow path; and a second detection means for detecting a state of the compressor. The control device includes: determining whether or not a subcooling abnormality occurs in which the refrigerant is not in a liquid state upstream of the pressure reducer in the second flow path based on a detection result of the first detection means; determining whether or not a surging phenomenon occurs in the compressor based on a detection result of the second detection means; When it is determined that the surging phenomenon occurs, adjusting at least one of a rotation speed of the fan and a rotation speed of the compressor so as to suppress the surging phenomenon; When it is determined that the surging phenomenon does not occur but the subcooling abnormality occurs, adjusting at least one of the rotation speed of the fan and the rotation speed of the compressor so as to suppress the subcooling abnormality; A battery cooling system configured to:

2. the control device is configured to determine, in determining the subcooling abnormality, whether a state of the refrigerant corresponds to a first state in which the subcooling abnormality occurs, a second state in which the subcooling abnormality is unlikely to occur, or a third state which is neither the first state nor the second state; The control device includes: When the surging phenomenon does not occur and the state of the refrigerant is determined to be in the first state, at least one of a rotation speed of the fan and a rotation speed of the compressor is accelerated; When the surging phenomenon does not occur and the state of the refrigerant is determined to be in the second state, at least one of the rotation speed of the fan and the rotation speed of the compressor is reduced; The battery cooling system of claim 1, configured so that when the surging phenomenon does not occur and the state of the refrigerant is determined to be in the third state, both the rotational speed of the fan and the rotational speed of the compressor are not changed.

3. The control device includes: determining whether a rotation speed of the fan is less than an upper limit value; determining whether a rotation speed of the compressor is greater than a lower limit value; configured to run The control device includes: When it is determined that the surging phenomenon does not occur, the state of the refrigerant is the first state, and the rotation speed of the fan is less than the upper limit value, the rotation speed of the fan is accelerated, When it is determined that the surging phenomenon does not occur, the state of the refrigerant is the first state, and the rotation speed of the fan is not less than the upper limit value, the rotation speed of the compressor is accelerated, When it is determined that the surging phenomenon does not occur, the state of the refrigerant is the second state, and the rotation speed of the compressor is greater than the lower limit value, the rotation speed of the compressor is reduced; The battery cooling system of claim 2, configured to slow down the rotational speed of the fan when it is determined that the surging phenomenon does not occur, the state of the refrigerant is in the second state, and the rotational speed of the compressor is not greater than the lower limit value.

4. The control device includes: determining whether a rotation speed of the fan is less than an upper fan rotation limit; determining whether a rotation speed of the compressor is less than an upper limit value; determining whether a rotation speed of the compressor is greater than a lower limit value; configured to run The control device includes: When it is determined that the surging phenomenon occurs when the rotation speed of the fan is less than the upper limit of the fan rotation, the rotation speed of the fan is accelerated; The battery cooling system of claim 1, configured to accelerate or decelerate the rotational speed of the compressor so as to suppress the surging phenomenon when it is determined that the surging phenomenon will occur when the rotational speed of the fan is not less than the fan rotation upper limit value and the rotational speed of the compressor is greater than the lower limit value and less than the upper limit value.

5. The first detection means is a pressure sensor for detecting a pressure of the refrigerant in the second flow path upstream of the pressure reducer; a temperature sensor for detecting a temperature of the refrigerant upstream of the pressure reducer in the second flow path; Including, The control device includes: calculating a saturation temperature of the refrigerant in the second flow path upstream of the pressure reducer based on the pressure of the refrigerant detected by the pressure sensor; determining whether or not the subcooling anomaly occurs based on the saturation temperature and the temperature of the refrigerant detected by the temperature sensor; configured to run The second detection means is a first pressure sensor for detecting a suction pressure of the refrigerant on a suction side of the compressor; a second pressure sensor for detecting a discharge pressure of the refrigerant on a discharge side of the compressor; a flow rate sensor for detecting a flow rate of the refrigerant flowing through the compressor; Including, The battery cooling system of any one of claims 1 to 4, wherein the control device is configured to identify an operating point of the compressor using the suction pressure, the discharge pressure, and the flow rate detected by the second detection means, and to determine whether or not the surging phenomenon will occur based on whether or not the identified operating point is included in a predetermined surging region.

Images