Battery cooling system

Abstract

To efficiently cool a battery module on a downstream side of a coolant flow.SOLUTION: A battery cooling system is configured to cool first and second battery modules. The battery cooling system includes a refrigerant circuit and a control device. The refrigerant circuit includes first and second coolers and first and second expansion valves, and coolant circulates. The control device controls the first and second expansion valves. The first and second coolers cool the first and second battery modules, respectively. The first cooler is arranged on an upstream side of the second cooler. The first expansion valve is arranged on an upstream side of the first cooler. The second expansion valve is arranged on the downstream side of the first cooler and on the upstream side of the second cooler. When temperature of the second battery module is higher than threshold, the controller controls the aperture of the second expansion valve so that it becomes greater than the aperture of the first expansion valve.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a battery cooling system that cools a plurality of battery modules. [Background technology]

[0002] Patent Document 1 discloses a cooling device for electrical equipment. This cooling device includes a refrigerant passage through which a refrigerant for vehicle interior air conditioning flows. The refrigerant passage has first and second porous pipe sections each having a porous pipe shape arranged in parallel with the flow direction of the refrigerant, and an inversion space section. The inversion space section agitates the refrigerant having a temperature difference by reversing the flow direction of the refrigerant between the first and second porous pipe sections by a partition wall provided between the first and second porous pipe sections. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-105880 A Summary of the Invention [Problem to be solved by the invention]

[0004] According to the refrigerant passage described in Patent Document 1, a low-temperature refrigerant flows upstream of the refrigerant passage, but downstream of the refrigerant passage, the refrigerant flows after having exchanged heat with an electrical device upstream. As a result, the amount of heat exchanged downstream is lower than that upstream. If the technology described in Patent Document 1 is applied to a battery cooling system that cools multiple battery modules in sequence (series), the amount of heat exchanged in the downstream battery modules may not be sufficient. As a result, the temperature variation between the battery modules may become large. Thus, the technology described in Patent Document 1 has room for improvement in terms of efficiently cooling the downstream battery module.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and has an object to provide a battery cooling system that can efficiently cool battery modules downstream in the refrigerant flow. [Means for solving the problem]

[0006] A battery cooling system according to the present disclosure is configured to cool a first and a second battery module. The battery cooling system includes a refrigerant circuit and a control device. The refrigerant circuit includes first and second coolers and first and second expansion valves, and a refrigerant circulates. The control device controls the first and second expansion valves. The first and second coolers cool the first and second battery modules, respectively. The first cooler is disposed upstream of the second cooler. The first expansion valve is disposed upstream of the first cooler. The second expansion valve is disposed downstream of the first cooler and upstream of the second cooler. When the temperature of the second battery module becomes higher than a threshold value, the control device controls the opening degree of the second expansion valve to be greater than the opening degree of the first expansion valve. Effect of the Invention

[0007] According to the battery cooling system of the present disclosure, the battery module downstream in the refrigerant flow can be efficiently cooled by controlling the opening degree of the second expansion valve described above. [Brief description of the drawings]

[0008] [Figure 1] A diagram showing a schematic configuration of a main part of a battery cooling system according to an embodiment. [Diagram 2] 2 is a block diagram showing an example of the configuration of a control system of the battery cooling system shown in FIG. 1. [Diagram 3] 5A to 5C are diagrams for explaining the effects of control of the expansion valve according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] An embodiment of the present disclosure will be described with reference to the accompanying drawings.

[0010] 1. Battery Cooling System Configuration Fig. 1 is a diagram showing a schematic configuration of a main part of a battery cooling system 10 according to an embodiment. The battery cooling system 10 is disposed, for example, in a battery pack 100 (see Fig. 2). The battery pack 100 is mounted on a vehicle and supplies power to an electric motor that drives the vehicle.

[0011] The battery pack 100 includes a plurality of battery modules. The battery cooling system 10 cools the plurality of battery modules. The plurality of battery modules includes, for example, three battery modules 1, 2, and 3 shown in FIG.

[0012] The battery cooling system 10 includes a refrigerant circuit 12 through which a refrigerant circulates. The refrigerant circuit 12 utilizes, for example, a refrigeration cycle and includes a plurality of coolers that cool the plurality of battery modules, respectively. The plurality of coolers are arranged in series on the refrigerant circuit 12. The plurality of coolers are heat exchangers for cooling, for example, evaporators.

[0013] The multiple coolers include three coolers 14, 16, and 18 that respectively cool the three battery modules 1, 2, and 3. As shown in Fig. 1, the three coolers 14, 16, and 18 are arranged in the order of cooler 14, cooler 16, and cooler 18 from the upstream side of the refrigerant flow. Refrigerant flow paths 14a, 16a, and 18a, which are part of the flow path of the refrigerant circuit 12, are formed inside the three coolers 14, 16, and 18, respectively.

[0014] The refrigerant circuit 12 also includes a plurality of expansion valves corresponding to the plurality of coolers, respectively. The plurality of expansion valves are electric (e.g., motorized or electromagnetic) expansion valves whose opening degree can be adjusted in response to a command from a control device 30 described later. The plurality of expansion valves include three expansion valves 20, 22, and 24 corresponding to the three coolers 14, 16, and 18, respectively. As shown in FIG. 1, the expansion valve 20 is disposed upstream of the cooler 14. The expansion valve 22 is disposed downstream of the cooler 14 and upstream of the cooler 16. Similarly, the expansion valve 24 is disposed downstream of the cooler 16 and upstream of the cooler 18.

[0015] In addition, devices such as a compressor and a condenser (not shown) are arranged in the refrigerant circuit 12. In the example shown in Fig. 1, in the relationship between the battery module 1 and the battery module 2, the battery modules 1 and 2 correspond to the "first and second battery modules" according to the present disclosure, respectively, and in the relationship between the battery module 2 and the battery module 3, the battery modules 2 and 3 correspond to the "first and second battery modules" according to the present disclosure, respectively. The same applies to the correspondence between the coolers 14, 16, and 18 and the "first and second coolers" and the correspondence between the expansion valves 20, 22, and 24 and the "first and second expansion valves."

[0016] FIG. 2 is a block diagram showing an example of the configuration of a control system of the battery cooling system 10 shown in FIG. 1. The battery cooling system 10 includes a control device 30. The control device 30 executes various processes related to the battery cooling system 10. The various processes include processes related to the control of a plurality of expansion valves such as the expansion valve 20. The control device 30 is, for example, an electronic control unit (ECU) including a processor and a storage device. The storage device stores various information required for processing by the processor. The processor executes a computer program stored in the storage device to realize the various processes by the control device 30. Alternatively, the various processes may be realized by hardware processing using dedicated electronic circuits.

[0017] Various sensors are connected to the control device 30. The various sensors include, for example, a plurality of refrigerant temperature sensors and a plurality of battery temperature sensors. As shown in FIG. 1 , the plurality of refrigerant temperature sensors include three refrigerant temperature sensors 32, 34, and 36 disposed upstream of the three coolers 14, 16, and 18, respectively. The plurality of battery temperature sensors include three battery temperature sensors 38, 40, and 42 that detect temperatures Tb of the three battery modules 1, 2, and 3, respectively.

[0018] 2. Expansion valve control In the battery cooling system 10 having the above-mentioned configuration, the opening of the expansion valve 22, etc. is controlled according to the amount of cooling required for the battery module 2, etc. located relatively downstream, thereby making it possible to adjust the temperature of the refrigerant flowing inside the cooler 16, etc. located relatively downstream. By adjusting the refrigerant temperature in this manner, it is possible to ensure the amount of heat exchange for the battery module 2, etc. corresponding to the cooler 16, etc. located downstream.

[0019] Therefore, in this embodiment, when the temperature Tb of the second battery module becomes higher than a predetermined threshold value TH, the control device 30 controls the opening degree of the second expansion valve so that the opening degree is greater than the opening degree of the first expansion valve.

[0020] More specifically, in the example shown in FIG. 1, when the temperature Tb of the battery module 2 becomes higher than a predetermined threshold TH1, the control device 30 controls the opening degree of the downstream expansion valve 22 so that the opening degree is greater than the opening degree of the upstream expansion valve 20. When the temperature Tb of the battery module 3 becomes higher than a predetermined threshold TH2, the control device 30 controls the opening degree of the downstream expansion valve 24 so that the opening degree is greater than the opening degree of the upstream expansion valve 22. Therefore, for example, when the temperatures Tb of the downstream battery modules 2 and 3 are higher than the respective thresholds TH1 and TH2, the control device 30 controls the opening degrees of the expansion valves 22 and 24 so that the opening degrees are greater in the order of the expansion valve 24>expansion valve 22>expansion valve 20. In addition, the thresholds TH such as the thresholds TH1 and TH2 may be set such that the temperature Tb of the second battery module is higher than the temperature Tb of the first battery module by a predetermined value.

[0021] Fig. 3 is a diagram for explaining the effect of the control of the expansion valve according to the embodiment. Fig. 3 shows changes in pressure and temperature of the refrigerant circulating in the refrigerant circuit 12 when the control of the expansion valve according to the embodiment is executed.

[0022] The refrigerant is compressed by the compressor, and the pressure and temperature of the refrigerant increase. When the refrigerant then passes through the expansion valve 20 upstream of the cooler 14, the pressure of the refrigerant is reduced and the temperature of the refrigerant drops, as indicated by the arrow A1 in Fig. 3. Then, the battery module 1 is cooled by heat exchange between the refrigerant and the battery module 1 in the cooler 14, and the refrigerant receives heat from the battery module 1, as indicated by the arrow A2.

[0023] Thereafter, when the refrigerant passes through expansion valve 22 downstream of expansion valve 20, the pressure of the refrigerant is reduced and the refrigerant temperature drops, as indicated by arrow A3. Then, the battery modules 2 are cooled by heat exchange between the refrigerant and the battery modules 2 in cooler 16 downstream of cooler 14, and the refrigerant receives heat from the battery modules 2, as indicated by arrow A4.

[0024] Similarly, when the refrigerant subsequently passes through expansion valve 24 downstream of expansion valve 22, the pressure of the refrigerant is reduced and the refrigerant temperature drops, as indicated by arrow A5. Then, the battery modules 3 are cooled by heat exchange between the refrigerant and the battery modules 3 in cooler 18 downstream of cooler 16, and the refrigerant receives heat from the battery modules 3, as indicated by arrow A6.

[0025] According to the control of the expansion valves in this embodiment, when the temperatures Tb of the downstream battery modules 2 and 3 are higher than the respective threshold values ​​TH1 and TH2, the openings of the expansion valves 22 and 24 are controlled so that the openings are larger in the order of expansion valve 24>expansion valve 22>expansion valve 20, as described above. That is, the openings of the expansion valves are controlled for each cooler (each refrigerant flow path). As a result, the temperature of the refrigerant flowing through the downstream coolers (coolers 16 and 18 in this case) can be lowered compared to the case where the openings of the expansion valves 20 to 24 are uniformly controlled. Therefore, the heat exchange amount of the downstream battery modules (battery modules 2 and 3 in this case) can be appropriately secured. As a result, the battery modules 1 to 3 can be cooled evenly. In addition, since there is no need to change the shape of the coolers 14 to 18, one standard part can be made versatile. [Explanation of symbols]

[0026] REFERENCE SIGNS LIST 1, 2, 3 battery module, 10 battery cooling system, 12 refrigerant circuit, 14, 16, 18 cooler, 14a, 16a, 18a refrigerant flow path, 20, 22, 24 expansion valve, 30 control device, 38, 40, 42 battery temperature sensor, 100 battery pack

Claims

[Claim 1] A battery cooling system for cooling first and second battery modules, a refrigerant circuit including first and second coolers and first and second expansion valves, in which a refrigerant circulates; A control device that controls the first and second expansion valves; Equipped with the first and second coolers cool the first and second battery modules, respectively; the first cooler is disposed upstream of the second cooler; the first expansion valve is disposed upstream of the first cooler; the second expansion valve is disposed downstream of the first cooler and upstream of the second cooler; When the temperature of the second battery module becomes higher than a threshold value, the control device controls the opening degree of the second expansion valve to be larger than the opening degree of the first expansion valve. A battery cooling system comprising:

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