Battery pack and battery cooling system

Abstract

To provide a battery pack capable of cooling cell bodies of a battery module and also appropriately cooling cell terminals.SOLUTION: A battery pack 1 includes a plurality of battery modules 10, a battery case 31, a water jacket 40 arranged in or inside the battery case 31 and through which a first refrigerant flows to exchange heat with the plurality of battery modules 10, a second evaporator 17 arranged in or inside the battery case 31 and through which a second refrigerant flows to exchange heat with the internal air, and a fan 13 arranged in or inside the battery case 31 and circulating the internal air.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to a battery pack that can be mounted on a moving object such as a vehicle, and a battery cooling system. [Background technology]

[0002] In recent years, efforts to realize a low-carbon or carbon-free society have become more active, and research and development into electrification technologies is being conducted in vehicles to reduce CO2 emissions and improve energy efficiency.

[0003] Batteries play an important role in electrification technology. Because batteries are heat-generating components, current is limited when the battery reaches a certain temperature or higher, for safety reasons and to prevent battery deterioration. For this reason, for example, a water jacket is provided in the battery pack, and cooling control is performed to keep the battery temperature within a desired temperature range.

[0004] Patent Document 1 describes providing water jackets between batteries arranged in multiple rows, and providing a cooling fan to blow air from the rear to the front of the battery case. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2003-297439 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, with recent battery developments, the heat resistance temperature of the cells that make up a battery module has increased. Therefore, while it was previously sufficient to cool the cells that make up a battery module, in recent years, there is a risk that the terminal temperature of the cell may reach the critical temperature for limiting the current, even if the cell temperature has not yet reached the critical temperature for limiting the current.

[0007] The battery cooling method described in Patent Document 1 can cool the outer surfaces of the battery module located at the front in the vehicle width direction by blowing air from a cooling fan, but does not mention cooling of the cell terminals.

[0008] The present invention provides a battery pack and a battery cooling system that are capable of cooling cell bodies of a battery module and also appropriately cooling cell terminals. [Means for solving the problem]

[0009] The battery pack of the present invention comprises: a plurality of cells having positive and negative terminals; A plurality of battery modules each including a plurality of the cells stacked therein; a battery case that houses the plurality of battery modules; a water jacket disposed in or inside the battery case, through which a first refrigerant flows and through which the water jacket exchanges heat with the battery modules; a heat exchanger that is disposed in or inside the battery case and through which a second refrigerant flows and exchanges heat with the air inside; and a fan disposed in or inside the battery case for circulating air therein.

[0010] In addition, the battery cooling system of the present invention includes: The battery pack; a refrigerant circuit in which the first refrigerant circulates through the water jacket; a heat pump circuit in which the second refrigerant circulates through the heat exchanger; a second heat exchanger capable of exchanging heat between the first refrigerant and the second refrigerant; and a control unit that controls the heat exchanger, the second heat exchanger, and the fan. Effect of the Invention

[0011] According to the present invention, it is possible to cool the cell bodies of the battery module, and further, it is possible to appropriately cool the cell terminals as well. [Brief description of the drawings]

[0012] [Figure 1] 1 is an exploded perspective view of a battery pack 1 according to a first embodiment. [Diagram 2] 1 is an exploded perspective view of a battery module 10. FIG. [Diagram 3] FIG. 2 is a perspective view of a laminated cell 21. [Figure 4] FIG. 2 is a perspective view showing a bus bar 22 that connects electrode tabs 212 of each laminated cell 21. [Diagram 5] FIG. 2 is a plan view showing the internal structure of the battery pack 1. [Figure 6] 6 is a cross-sectional view taken along line AA in FIG. 5. [Figure 7] 6 is a cross-sectional view taken along line BB in FIG. 5. [Figure 8] 6 is a cross-sectional view taken along line CC in FIG. 5. [Figure 9] FIG. 6 is a cross-sectional view taken along line DD in FIG. 5. [Figure 10] 2 is a plan view showing the internal structure of the battery pack 1, and diagrammatically illustrating the air flow caused by the fan 13. FIG. [Figure 11] FIG. 1 illustrates a battery cooling system 100. [Figure 12] 6 is a timing chart of battery cooling control in a case where quick charging is started in a state where the cell temperature is lower than the cell cooling start temperature by a predetermined amount or more. [Figure 13] 6 is a timing chart of battery cooling control in a case where quick charging is started in a state where the cell temperature is close to the cell cooling start temperature. [Figure 14] 11 is a plan view showing the internal structure of a battery pack 1A of a second embodiment, and also shows a schematic diagram of the air flow caused by a fan 13. FIG. [Figure 15] 15 is a cross-sectional view taken along line EE in FIG. 14. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, battery packs according to embodiments of the present invention will be described with reference to the accompanying drawings.

[0014] [First embodiment] A battery pack 1 according to a first embodiment of the present invention is configured to be mountable on an electric vehicle such as a hybrid vehicle, an electric vehicle, or a fuel cell vehicle. As shown in Fig. 1, the battery pack 1 includes four battery modules 10, a junction box 11, an auxiliary device 12, and a battery case 31 that houses these. The four battery modules 10 are arranged in two rows in the front-rear direction and two rows in the left-right direction. The number of battery modules 10 can be set arbitrarily as long as it is two or more, and the arrangement is not particularly limited.

[0015] The battery modules 10 are electrically connected to each other via electrical connection members (not shown). The power stored in the battery modules 10 is supplied to a motor or the like that serves as a drive source for the vehicle. In the following description, the four battery modules 10 may be collectively referred to as a battery.

[0016] As shown in FIG. 2, the battery module 10 includes a cell stack 20 in which a plurality of laminated cells 21 are stacked, an intermediate plate 30, a pair of end plates 37, a pair of restraining members 38, and a pair of cover plates 60.

[0017] The laminated cell 21 is, for example, a solid-state battery. As shown in FIG. 3, the laminated cell 21 made of a solid-state battery has a positive electrode connected to a positive electrode tab 21a, a negative electrode connected to a negative electrode tab 21b, a solid electrolyte disposed between the positive electrode and the negative electrode, and a laminated film 21c that accommodates them, and charges and discharges by receiving and transferring lithium ions between the positive electrode and the negative electrode via the solid electrolyte. In addition, a seal portion 211 is provided on the periphery of the laminated cell 21. The positive electrode tab 21a extends from the seal portion 211 at one end side in the longitudinal direction of the laminated cell 21, and the negative electrode tab 21b extends from the seal portion 211 at the other end side in the longitudinal direction of the laminated cell 21. The positive electrode tab 21a and the negative electrode tab 21b may both extend from the seal portion 211 at one end side in the longitudinal direction of the laminated cell 21. Hereinafter, the positive electrode tab 21a and the negative electrode tab 21b are collectively referred to as electrode tabs 212. Note that the electrolyte used in the laminated cell 21 is not limited to a solid electrolyte, and may be a semi-solid electrolyte or a liquid electrolyte.

[0018] 4, the cell stack 20 is configured by stacking a plurality of laminated type cells 21 in the left-right direction. In this embodiment, each laminated type cell 21 is arranged such that an electrode tab 212 extends in the front-rear direction. Each laminated type cell 21 is electrically connected via a bus bar 22.

[0019] Returning to Fig. 2, the intermediate plate 30 is provided in the middle in the stacking direction (here, the left-right direction) of the plurality of laminated cells 21. Two or more intermediate plates 30 may be provided.

[0020] The pair of end plates 37 are provided at both ends of the laminated cells 21 in the stacking direction.

[0021] The pair of restraining members 38 face each other in the up-down direction and are connected to the pair of end plates 37 to restrain the multiple laminated cells 21. Here, the pair of restraining members 38 have a plate shape and cover the multiple laminated cells 21, the intermediate plate 30, and the pair of end plates 37 from the up-down direction. In this example, the restraining members 38 are plate-shaped, but as long as they can restrain the end plates 37 in the stacking direction, their shape may be a ladder shape, rod-shaped restraint, or the like that does not cover and conceal the cells.

[0022] The pair of cover plates 60 are provided outside the laminated cells 21 in the front-rear direction and extend in the stacking direction. When viewed from the front-rear direction, the cover plates 60 cover the bus bars 22 and the electrode tabs 212 of each laminated cell 21 via the electrically insulating bus bar covers 23, thereby protecting the bus bars 22 and the electrode tabs 212.

[0023] Returning to Fig. 1, the battery case 31 has a battery tray 32 on which a plurality of battery modules 10 are placed, and an upper cover 33 that covers the upper side of the battery modules 10. An upper gap 15 is provided between the battery modules 10 and the upper cover 33, as shown in Figs.

[0024] As shown in FIG. 5, the battery tray 32 includes a bottom plate 321 on which the battery module 10 is placed, a pair of side frames 322 provided on both the left and right sides of the bottom plate 321, and a front cross member 333, a central cross member 334, and a rear cross member 335 that connect the pair of side frames 322.

[0025] The front cross member 333 forms a front wall of the battery case 31, and the rear cross member 335 forms a rear wall of the battery case 31. The central cross member 334 divides the interior of the battery case 31 into two spaces, a front space and a rear space. Two battery modules 10 are arranged on the left and right in the front space, and two battery modules 10 are arranged on the left and right in the rear space.

[0026] An upper frame 34 extending in the front-rear direction is bridged over the two battery modules 10 located on the left side and the two battery modules 10 located on the right side in the left-right center of the battery case 31. A junction box 11 is disposed in the front of the upper frame 34, and an auxiliary device 12 is disposed in the rear. In the junction box 11, electronic components such as conductive members, fuses, contactors, etc. that connect the power system inside the battery case 31 and the DC line outside the battery case 31 are disposed. The auxiliary device 12 is, for example, a battery ECU.

[0027] As shown in FIGS. 6 to 9, a cover plate is attached below the bottom plate 321, and a water jacket 40 is formed between the bottom plate 321 and the cover plate .

[0028] The water jacket 40 is provided over substantially the entire surface of the bottom plate 321. If an area in the internal space of the battery case 31 where the battery module 10 is arranged is defined as a first section 51, and an area where the battery module 10 is not arranged is defined as a second section 52, the water jacket 40 is provided across the first section 51 and the second section 52. In the first section, heat exchange occurs between the battery module 10 and the water jacket 40. The battery module 10 and the bottom plate 321 may be in direct contact with each other, or indirectly in contact with each other via a heat transfer material.

[0029] The second compartment 52 is provided on both the left and right sides above the water jacket 40 and outside the first compartment 51. That is, the second compartment 52 has a left gap 521 between the two battery modules 10 located on the left side and the left side frame 322, and a right gap 522 between the two battery modules 10 located on the right side and the right side frame 322.

[0030] The interior of the battery case 31 has a front gap 523 between the two battery modules 10 located on the front side and the front cross member 333, a central front gap 524 between the two battery modules 10 located on the front side and the central cross member 334, a central rear gap 526 between the two battery modules 10 located on the rear side and the central cross member 334, and a rear gap 527 between the two battery modules 10 located on the rear side and the rear cross member 335. The front gap 523, the central front gap 524, the central rear gap 526, and the rear gap 527 are perpendicular to the extension direction of the left gap 521 and the right gap 522 that constitute the second section 52, and form an air passage that connects the left gap 521 and the right gap 522.

[0031] The water jacket 40 is connected to a battery cooling circuit 18 of a battery cooling system 100 shown in Fig. 11. The battery cooling system 100 includes the battery cooling circuit 18 in which a first refrigerant (e.g., LLC) circulates through the water jacket 40, a heat pump circuit 19 in which a second refrigerant (e.g., an air conditioner refrigerant) different from the first refrigerant circulates, a chiller 42 capable of heat exchange between the first refrigerant and the second refrigerant, a fan 13, and a control unit 14 that controls these.

[0032] The battery cooling circuit 18 is provided outside the battery case 31 and connected to the battery case 31 by piping. The battery cooling circuit 18 includes a main flow path 45 including a water jacket 40, a radiator 41, a chiller 42, a heater 43, and an electric pump 44, and a bypass flow path 47 that bypasses the radiator 41 of the main flow path 45.

[0033] The bypass flow path 47 connects a branching portion 46a located between the water jacket 40 and the radiator 41 and a junction portion 46b located between the radiator 41 and the chiller 42. A three-way valve 48 is provided at the branching portion 46a. The control unit 14 switches the three-way valve 48 between a bypass-off state and a bypass-on state. When the three-way valve 48 is in the bypass-off state, the first refrigerant delivered from the electric pump 44 circulates through the water jacket 40, the radiator 41, the chiller 42, and the heater 43. On the other hand, when the three-way valve 48 is in the bypass-on state, the first refrigerant delivered from the electric pump 44 bypasses the radiator 41 and circulates through the water jacket 40, the chiller 42, and the heater 43. The heater 43 is controlled between an on state and an off state by the control unit 14.

[0034] The battery cooling circuit 18 is driven in a stop mode, a heating mode, a normal mode, and a cooling mode by the control unit 14. The stop mode is set, for example, when the vehicle is parked. In the stop mode, the electric pump 44 does not operate. The heating mode is set, for example, when the battery is at a low temperature. In the heating mode, the three-way valve 48 is in a bypass-on state, and the first refrigerant is heated by the heater 43 while heat radiation from the radiator 41 is blocked, thereby heating the battery. The normal mode is set, for example, when the vehicle is running. In the normal mode, the three-way valve 48 is in a bypass-off state, and the heat of the refrigerant is radiated from the radiator 41, thereby cooling the battery. The cooling mode is set, for example, when the temperature of the battery is high while the vehicle is running, or when the vehicle is being charged (including quick charging). In the cooling mode, in addition to radiating heat from the radiator 41, the first refrigerant exchanges heat with the second refrigerant of the heat pump circuit 19 in the chiller 42, thereby further cooling the battery. During charging or the like, the heat exchange capacity of the radiator 41 is limited, so heat exchange by the chiller 42 becomes effective.

[0035] The heat pump circuit 19 is, for example, a refrigeration cycle for vehicle air conditioning. The heat pump circuit 19 includes a main flow path 70 and a battery cooling flow path 80 branched from the main flow path 70. The main flow path 70 includes a compressor 71, a condenser 72, a first shutoff valve 73, a first expansion valve 74, and a first evaporator 75, arranged in this order in the flow direction of the second refrigerant.

[0036] The battery cooling flow path 80 connects a first branch portion 77 located between the condenser 72 and the first shutoff valve 73 to a first junction portion 78 located between the first evaporator 75 and the compressor 71.

[0037] The battery cooling flow path 80 is provided with a second branching section 83 that branches the battery cooling flow path 80 into an evaporator flow path 81 and a chiller flow path 82, and a second junction section 84 where the evaporator flow path 81 and the chiller flow path 82 join. The chiller flow path 82 includes, from the second branching section 83, a second shutoff valve 85, a second expansion valve 86, and a chiller 42, in this order in the flow direction of the second refrigerant. The evaporator flow path 81 includes, from the second branching section 83, a third shutoff valve 87, a third expansion valve 88, and a second evaporator 17, in this order in the flow direction of the second refrigerant.

[0038] In the heat pump circuit 19, the first shutoff valve 73, the second shutoff valve 85, and the third shutoff valve 87 are on / off controlled by the control unit 14. When there is a demand for cooling the vehicle interior, the control unit 14 controls the first evaporator 75 to the on state by controlling the first shutoff valve 73 to the on state, and when there is no demand for cooling the vehicle interior, the control unit 14 controls the first evaporator 75 to the off state by controlling the first shutoff valve 73 to the off state.

[0039] Furthermore, when the temperature of the laminated cell 21 (hereinafter referred to as the cell temperature) becomes equal to or higher than the cell cooling start temperature (first threshold), the control unit 14 controls the chiller 42 to the on state by turning on the second shutoff valve 85, and when the cell temperature is lower than the cell cooling start temperature, the control unit 14 controls the chiller 42 to the off state by controlling the second shutoff valve 85 to the off state. As a result, when the cell temperature is high, the first refrigerant flowing through the battery cooling circuit 18 is cooled by the chiller 42, improving the cooling capacity of the water jacket 40.

[0040] 5, when the first refrigerant is supplied to the water jacket 40, the battery module 10 in the first section 51 is cooled via the bottom plate 321. At this time, the laminated cell 21 itself that abuts against the bottom plate 321 is cooled well, but the electrode tab 212 of the laminated cell 21 that is separated from the bottom plate 321 is difficult to cool, and there is a risk that the temperature of the electrode tab 212 will exceed a threshold value, causing current limitation of the battery.

[0041] Therefore, when the temperature of the electrode tab 212 of the laminated cell 21 (hereinafter referred to as the tab temperature) becomes equal to or higher than the tab cooling start temperature (second threshold value), the control unit 14 controls the third shutoff valve 87 to the on state, thereby controlling the second evaporator 17 to the on state, and also controls the fan 13 to the on state. On the other hand, when the tab temperature is lower than the tub cooling start temperature, the control unit 14 controls the third shutoff valve 87 to the off state, thereby controlling the second evaporator 17 to the off state, and also controls the fan 13 to the off state.

[0042] In the present disclosure, a fan 13 and a second evaporator 17 are provided inside the battery case 31. When the fan 13 is driven, air circulates between the first compartment 51 and the second compartment 52. The electrode tabs 212 are in contact with the air circulating inside the battery case 31, and therefore dissipate heat from the cell terminals to the second evaporator 17 as the air passes through the second evaporator 17. This allows the electrode tabs 212 of the laminated type cells 21 to be appropriately cooled.

[0043] Two fans 13 are provided inside the battery case 31 in this embodiment; one is provided in the right gap 522 of the second section 52, rearward of the central cross member 334, and the other is provided in the left gap 521 of the second section 52, forward of the central cross member 334. These two fans 13 are arranged so as to blow air in opposite directions in the front-rear direction. The second evaporator 17 may be provided anywhere in the battery case 31 or inside the battery case 31, but in this embodiment, it is arranged adjacent to and rearward of the fan 13 provided in the left gap 521.

[0044] In this embodiment, as shown in Fig. 10, the right fan 13 blows air forward, and the left fan 13 blows air backward. The air blown out from the fan 13 flows forward or backward through the gap around the central cross member 334. Therefore, in the right gap 522, the front of the right fan 13 becomes a positive pressure area and the rear becomes a negative pressure area, whereas in the left gap 521, the front of the left fan 13 becomes a negative pressure area and the rear becomes a positive pressure area. As a result, a pressure distribution is formed in the battery case 31 in the left-right direction, from the positive pressure area of ​​the second compartment 52 to the first compartment 51 (battery module 10) to the negative pressure area of ​​the second compartment 52, and air circulation in the battery case 31 can be smooth.

[0045] That is, as shown by the arrows in Fig. 10, inside the battery case 31, the air sent out from the right fan 13 flows from the front of the right gap 522 (positive pressure area of ​​the right fan 13), through the upper parts (upper gap 15) of the two battery modules 10 located at the front side, to the front of the left gap 521 (negative pressure area of ​​the left fan 13), and is sucked into the left fan 13. Also, the air sent out from the left fan 13 flows from the rear of the left gap 521 (positive pressure area of ​​the left fan 13), through the upper parts (upper gap 15) of the two battery modules 10 located at the rear side, to the rear of the right gap 522 (negative pressure area of ​​the right fan 13), and is sucked into the right fan 13. This allows the upper parts of the laminated type cells 21 (upper parts of the battery modules 10) to be cooled.

[0046] In addition, since the junction box 11 attached to the upper frame 34 is disposed above the two battery modules 10 located on the front side, the junction box 11 is also cooled. In particular, the conductive members of the junction box 11 come into contact with the air circulating through the first compartment 51 and the second compartment 52, so that current limitation due to heat generation of the conductive members can be avoided.

[0047] Also, a portion of the air sent out from the right fan 13 flows from the front of the right gap 522 (positive pressure region of the right fan) through the front gap 523 and the central front gap 524 to the front of the left gap 521 (negative pressure region of the left fan 13) and is sucked into the left fan 13. Also, a portion of the air sent out from the left fan 13 flows through the rear gap 527 and the central rear gap 526 to the rear of the right gap 522 (negative pressure region of the right fan 13) and is sucked into the right fan 13. This enables the electrode tabs 212 of the laminate type cells 21 to be cooled.

[0048] More specifically, the air passing through the air passages of the front gap 523, the central front gap 524, the rear gap 527, and the central rear gap 526 cools the electrode tabs 212 of the laminated cells 21 while traveling through the spaces 25 formed between the electrode tabs 212 of the laminated cells 21 and the busbar covers 23 and extending in the stacking direction, as shown in Fig. 9. In this way, the spaces 25 formed between the electrode tabs 212 of the laminated cells 21 and the busbar covers 23 are connected in the stacking direction, so that the electrode tabs 212 of the laminated cells 21 located in the vicinity of the cross members 333 to 335 can be appropriately cooled.

[0049] In the battery pack 1 configured in this manner, the electrode tab 212 of the laminated cell 21 in the first compartment 51 is in contact with the air circulating inside the battery case 31, so that heat from the electrode tab 212 of the laminated cell 21 can be dissipated through the air to the second evaporator 17. This allows the temperature of the electrode tab 212 to be lowered, suppressing current limitation caused by the temperature of the electrode tab 212 and allowing the battery capacity to be used effectively.

[0050] In addition, the upper part of the laminated cell 21 dissipates heat to the second evaporator 17 via the air, and the lower part of the laminated cell 21 dissipates heat to the water jacket 40 located below the laminated cell 21 in the first section 51, thereby suppressing temperature variations between the upper and lower parts of the laminated cell 21.

[0051] Fig. 12 and Fig. 13 are graphs explaining the cooling control of the battery. Fig. 12 is a timing chart of the battery cooling control when rapid charging is started in a state where the cell temperature is lower than the cell cooling start temperature by a predetermined amount or more, and Fig. 13 is a timing chart of the battery cooling control when rapid charging is started in a state where the cell temperature is close to the cell cooling start temperature.

[0052] The control unit 14 operates the battery cooling circuit 18 in normal mode in accordance with the start of rapid charging. As shown in FIG. 12, when rapid charging is started and the tub temperature of the laminated cell 21 reaches the tub cooling start temperature, the control unit 14 controls the second evaporator 17 and the fan 13 to the ON state. That is, when the tub temperature of the laminated cell 21 is equal to or higher than the tub cooling start temperature, the control unit 14 controls the third shutoff valve 87 of the heat pump circuit 19 to the ON state, thereby controlling the second evaporator 17 to the ON state and controlling the fan 13 to the ON state. This suppresses the rise in the temperature inside the case and also slows down the rise in the tub temperature, preventing the tub temperature from reaching the tub upper limit temperature.

[0053] Next, when the cell temperature of the laminated cell 21 reaches the cell cooling start temperature, the control unit 14 controls the chiller 42 to the on state (the cooling mode described above). That is, when the cell temperature of the laminated cell 21 is equal to or higher than the cell cooling start temperature, the control unit 14 controls the chiller 42 to the on state by controlling the second shutoff valve 85 of the heat pump circuit 19 to the on state. This reduces the temperature of the first refrigerant (LLC temperature in the figure, hereinafter referred to as the first refrigerant temperature) and suppresses an increase in the cell temperature, preventing the cell temperature from reaching the cell upper limit temperature.

[0054] When quick charging is completed and the tub temperature of the laminated cell 21 falls below the tub cooling start temperature, the control unit 14 controls the second evaporator 17 and the fan 13 to the off state. Next, when the cell temperature of the laminated cell 21 falls below the cell cooling start temperature, the control unit 14 controls the chiller 42 to the off state.

[0055] 13, when rapid charging is started and the cell temperature of the laminated cell 21 reaches the cell cooling start temperature, the control unit 14 controls the chiller 42 to the on state. That is, when the cell temperature of the laminated cell 21 is equal to or higher than the cell cooling start temperature, the control unit 14 controls the chiller 42 to the on state by controlling the second shutoff valve 85 of the heat pump circuit 19 to the on state. This reduces the first refrigerant temperature (LLC temperature in the figure) and suppresses the rise in the cell temperature, preventing the cell temperature from reaching the cell upper limit temperature.

[0056] Next, when the tub temperature of the laminated cell 21 reaches the tub cooling start temperature, the control unit 14 controls the second evaporator 17 and the fan 13 to the ON state. That is, when the tub temperature of the laminated cell 21 is equal to or higher than the tub cooling start temperature, the control unit 14 controls the second evaporator 17 to the ON state by controlling the third shutoff valve 87 of the heat pump circuit 19 to the ON state, and also controls the fan 13 to the ON state. This suppresses the rise in the temperature inside the case and also slows down the rise in the tub temperature, preventing the tub temperature from reaching the tub upper limit temperature.

[0057] When quick charging is completed and the tub temperature of the laminated cell 21 falls below the tub cooling start temperature, the control unit 14 controls the second evaporator 17 and the fan 13 to the off state. Next, when the cell temperature of the laminated cell 21 falls below the cell cooling start temperature, the control unit 14 controls the chiller 42 to the off state.

[0058] In this manner, in the above-described cooling control of the battery, the objects to be monitored for temperature are different: cooling of the laminated cell 21 by the water jacket 40 and cooling of the electrode tab 212 by the air. The control unit 14 controls the battery cooling circuit 18 according to the temperature of the laminated cell 21, so that the ability of the water jacket 40 to cool the laminated cell 21 in the first section 51 changes according to the temperature of the laminated cell 21. On the other hand, the control unit 14 controls the second evaporator 17 and the fan 13 according to the temperature of the electrode tab 212, so that the ability of the air inside the battery case 31 to cool the electrode tab 212 changes according to the temperature of the electrode tab 212. Therefore, compared to a case where the object to be monitored for the operation of the chiller 42 and the object to be monitored for the operation of the second evaporator 17 and the fan 13 are the same object, it is possible to more effectively prevent current limitation due to the temperature of the electrode tab 212 while maintaining the temperature of the laminated cell 21 at an appropriate temperature.

[0059] The method of measuring the temperature is not limited to directly measuring the temperature of the laminated cell 21 or the electrode tab 212 by contacting a temperature sensor with the laminated cell 21 or the electrode tab 212, but the temperatures of the laminated cell 21 or the electrode tab 212 may be estimated from the temperatures of parts that reflect the temperatures of the laminated cell 21 or the electrode tab 212. For example, the temperature of the electrode tab 212 may be estimated from the temperature of the air around the cell terminals. The temperature of the laminated cell 21 may also be estimated from the refrigerant temperature on the outlet side of the water jacket 40.

[0060] [Second embodiment] Next, a battery pack 1A of a second embodiment will be described with reference to Fig. 14 and Fig. 15. In the following, only the differences from the battery pack 1 of the first embodiment will be described. In the drawings, the same components as those of the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted.

[0061] As shown in Fig. 14, the battery pack 1A of the second embodiment includes eight battery modules 10A, a junction box 11, an auxiliary device 12, and a battery case 31 that houses them. The eight battery modules 10A are arranged in two rows in the front-rear direction and four rows in the left-right direction. Note that the number of battery modules 10A can be set arbitrarily as long as it is two or more, and the arrangement is not particularly limited.

[0062] In the battery module 10A, a pair of end plates arranged at both ends in the stacking direction of a cell stack 20A in which a plurality of rectangular cells 21A are stacked are connected by a pair of restraining members 38A arranged laterally, and a positive electrode terminal 21a1 and a negative electrode terminal 21b1 provided on the upper part of the rectangular cell 21A are covered by a bus bar cover 23A. A space 25 through which air passes is connected in the stacking direction between the positive electrode terminal 21a1 and the negative electrode terminal 21b1 and the bus bar cover 23A.

[0063] That is, in the battery module 10A of the second embodiment, a positive electrode terminal 21a1 and a negative electrode terminal 21b1 are provided on the upper part of the prismatic cell 21A. Note that, instead of the prismatic cell 21A, cylindrical cells may be stacked.

[0064] In the battery pack 1A thus configured, when the second evaporator 17 and the fan 13 of the battery case 31 in which the battery module 10A is mounted are driven, as shown by the arrows in Fig. 14, similar to the arrows in Fig. 10 of the first embodiment, the air sent out from the right fan 13 flows from the front of the right gap 522 (positive pressure area of ​​the right fan 13), through the upper parts (upper gap 15) of the four battery modules 10 located on the front side, to the front of the left gap 521 (negative pressure area of ​​the left fan 13), and is sucked into the left fan 13. Also, the air sent out from the left fan 13 flows from the rear of the left gap 521 (positive pressure area of ​​the left fan 13), through the upper parts (upper gap 15) of the four battery modules 10 located on the rear side, to the rear of the right gap 522 (negative pressure area of ​​the right fan 13), and is sucked into the right fan 13. The air passing through the upper gap 15 cools the positive electrode terminal 21a1 and the negative electrode terminal 21b1 of the rectangular cell 21A while flowing through a space 25 formed between the positive electrode terminal 21a1 and the negative electrode terminal 21b1 of the rectangular cell 21A and the bus bar cover 23A and extending in the stacking direction. This allows the upper part of the rectangular cell 21A (the upper part of the battery module 10A) to be cooled, and the positive electrode terminal 21a1 and the negative electrode terminal 21b1 to be cooled.

[0065] In this embodiment as well, a portion of the air sent out by the fan 13 passes through the front gap 523, the central front gap 524, the rear gap 527, and the central rear gap 526. The air passing through the front gap 523, the central front gap 524, the rear gap 527, and the central rear gap 526 cools the side surfaces of the rectangular cells 21A (the side surfaces of the battery module 10A).

[0066] In this manner, also in the battery pack 1A, the positive electrode terminal 21a1 and the negative electrode terminal 21b1 of the prismatic cell 21A in the first compartment 51 are in contact with the air circulating inside the battery case 31, so that the heat of the positive electrode terminal 21a1 and the negative electrode terminal 21b1 of the prismatic cell 21A can be dissipated through the air to the second evaporator 17 in the second compartment 52. This makes it possible to lower the temperatures of the positive electrode terminal 21a1 and the negative electrode terminal 21b1, thereby preventing current limitation due to the temperatures of the positive electrode terminal 21a1 and the negative electrode terminal 21b1, and enabling the battery capacity to be used effectively.

[0067] In addition, the upper part of the rectangular cell 21A dissipates heat to the second evaporator 17 via the air, and the lower part of the rectangular cell 21A dissipates heat to the water jacket 40 located below the rectangular cell 21A in the first section 51, thereby suppressing temperature variation between the upper and lower parts of the rectangular cell 21A.

[0068] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can come up with various modified or revised examples within the scope of the claims, and it is understood that these also naturally belong to the technical scope of the present invention. Furthermore, the components in the above-mentioned embodiments may be arbitrarily combined within the scope of the invention.

[0069] For example, the second evaporator 17 and the fan 13 are not limited to being provided inside the battery case 31, but may be provided in the battery case 31. By providing the fan 13 in the battery case 31, it is possible to take air outside the battery case 31 into the inside. In addition, the number of fans 13 is not limited to two, but may be one, or three or more.

[0070] Furthermore, the water jacket 40 is not limited to being formed by the bottom plate 321 and the cover plate 36, but may be a separate water jacket that is attached externally or may be provided inside the battery case 31.

[0071] This specification describes at least the following items. Note that, in parentheses, components corresponding to those in the above-mentioned embodiment are shown, but the present invention is not limited to these.

[0072] (1) A plurality of cells (laminated type cells 21, rectangular cells 21A) each having a positive electrode terminal (positive electrode tab 21a, positive electrode terminal 21a1) and a negative electrode terminal (negative electrode tab 21b, negative electrode terminal 21b1), A plurality of battery modules (battery modules 10, 10A) in which the plurality of cells are stacked; A battery case (battery case 31) that houses the plurality of battery modules; A water jacket (water jacket 40) that is disposed in or inside the battery case and through which a first refrigerant flows and exchanges heat with the plurality of battery modules; a heat exchanger (second evaporator 17) disposed in or inside the battery case, through which a second refrigerant flows and exchanges heat with the air inside; A battery pack (battery pack 1, 1A) including a fan (fan 13) disposed in or inside the battery case for circulating air therein.

[0073] According to (1), the cell terminals come into contact with the air circulating inside the battery case by the fan, so that the heat of the cell terminals can be dissipated to the heat exchanger when the air passes through the heat exchanger. In addition, the cell body dissipates heat to the water jacket. This allows the temperature of the cell terminals and the temperature of the cells to be lowered, so that the application of current limiting due to the temperature of the cell terminals is suppressed, and the application of current limiting due to the temperature of the cells is also suppressed. This prevents the current limiting of the battery from taking effect, and allows the battery capacity to be appropriately utilized.

[0074] (2) A battery pack according to (1), The water jacket cools the battery modules from below, The battery case includes: a first compartment (first compartment 51) in which the plurality of battery modules are arranged and heat exchange occurs between the plurality of battery modules and the water jacket; a second compartment (second compartment 52) ​​above the water jacket, in which the plurality of battery modules are not arranged; the battery pack having a gap (upper gap 15) provided between the plurality of cells and an inner wall of the battery case, through which air can pass.

[0075] According to (2), air can be circulated properly.

[0076] (3) A battery pack according to (2), The battery case houses a junction box (junction box 11), The junction box is positioned such that air circulated between the first compartment and the second compartment by the fan comes into contact with a conductive member of the junction box.

[0077] According to (3), the air flow inside the battery case also cools the conductive components of the junction box, thereby preventing current limiting during rapid charging, etc.

[0078] (4) A battery pack according to (2), The second section is located outside the first section and on both sides of the first section, The heat exchanger and the fan are disposed in the second compartment.

[0079] According to (4), the heat exchanger and fan are installed in the second compartment, which is used as a collision stroke where the battery module is not located, so that the space within the battery pack can be used more effectively and the increase in the height of the battery pack can be suppressed compared to the case where the fan is installed above the battery module (first compartment).

[0080] (5) A battery pack according to (4), The fans are disposed in the second compartments, The second compartments each include a positive pressure region on the side of the fan where air is exhausted from the fan; a negative pressure region on the side of the fan where the air is introduced into the fan; The positive pressure region of the second compartment on one side and the negative pressure region of the second compartment on the other side face each other across the first compartment, The battery pack, wherein the negative pressure region of the second compartment on one side and the positive pressure region of the second compartment on the other side face each other with the first compartment therebetween.

[0081] According to (5), a pressure distribution is formed in the order of positive pressure region in the second compartment → first compartment (battery module) → negative pressure region in the second compartment, thereby making it possible to more smoothly circulate air inside the battery case.

[0082] (6) A battery pack according to (1), The plurality of battery modules each have a terminal insulating cover (bus bar cover 23, 23A) that covers at least one of the positive electrode terminal and the negative electrode terminal of the cell (electrode tab 212), The battery pack comprises a space (space 25) extending in the stacking direction of the cells between the terminal insulating cover and the cell terminal.

[0083] According to (6), the space around the cell terminal serves as an air passage, so that the cell terminal can be efficiently cooled while being insulated.

[0084] (7) A battery pack according to (2), The second section is located outside the first section and on both sides of the first section, Between adjacent battery modules or between the battery modules and the cross members (front cross member 333, center cross member 334, rear cross member 335), A battery pack in which air passages (front gap 523, central front gap 524, central rear gap 526, rear gap 527) are formed that are perpendicular to the extension direction of the second compartment and connect the second compartment on one side to the second compartment on the other side.

[0085] When there are cell terminals on both sides of a cell, one of the terminals is located on the side closer to the other battery module or the cross member. According to (7), by providing an air passage between adjacent battery modules or between a battery module and the cross member, the cell terminals closer to the other battery module or the cross member can also be cooled more efficiently than when the battery modules are placed in close contact with each other without providing an air passage.

[0086] (8) A battery pack according to any one of (1) to (7), a refrigerant circuit (battery cooling circuit 18) in which the first refrigerant circulates through the water jacket; a heat pump circuit (heat pump circuit 19) through which the second refrigerant circulates through the heat exchanger; a second heat exchanger (chiller 42) capable of exchanging heat between the first refrigerant and the second refrigerant; A battery cooling system (battery cooling system 100) comprising: a control unit (control unit 14) that controls the heat exchanger, the second heat exchanger, and the fan.

[0087] According to (8), the first refrigerant dissipates heat to the heat pump circuit via the second refrigerant in the second heat exchanger, and the air inside the battery case also dissipates heat to the heat exchanger of the heat pump circuit, so that the inside of the battery case can be appropriately cooled by a single heat pump circuit.

[0088] (9) A battery cooling system according to (8), The control unit is When the temperature of the cell is higher than a first threshold (cell cooling start temperature), the second heat exchanger is controlled to an on state; When the terminal temperature of the cell is higher than a second threshold (tab cooling start), the heat exchanger and the fan are controlled to be in an on state. Battery cooling system.

[0089] According to (9), the objects to be monitored for the temperature are different between cooling the cell by the water jacket and cooling the cell terminal by air, and the ability of the water jacket to cool the cell changes according to the cell temperature, while the ability of the air in the battery case to cool the cell terminal changes according to the temperature of the cell terminal. This makes it possible to more effectively suppress current limitation due to the temperature of the cell terminal while maintaining the cell temperature at an appropriate temperature. The temperature measurement method is not limited to directly measuring the cell temperature or the cell terminal temperature by contacting a temperature sensor with the cell or cell terminal, and the cell or cell terminal temperature may be estimated from the temperature of a part that reflects the cell or cell terminal temperature. For example, the cell terminal temperature may be estimated from the temperature of the air around the cell terminal. The cell temperature may also be estimated from the refrigerant temperature on the outlet side of the water jacket.

[0090] (10) The battery cooling system according to (8), The heat pump circuit has a branch portion (second branch portion 83) to a flow path flowing to the heat exchanger, upstream of the flow path flowing to the second heat exchanger. Battery cooling system.

[0091] According to (10), by providing the branch portion upstream of the second heat exchanger, it is possible to supply the cold second refrigerant to the heat exchanger before heat exchange in the second heat exchanger. [Explanation of symbols]

[0092] 1, 1A battery pack 10, 10A Battery Module 11 Junction Box 13 Fan 14 Control section 15 Upper gap (gap) 17 Second evaporator (heat exchanger) 18 Battery cooling circuit (refrigerant circuit) 19 Heat pump circuit 21 Laminated cell (cell) 21A Square Cell (Cell) 21a Positive electrode tab (positive electrode terminal) 21a1 Positive terminal (positive terminal) 21b Negative tab (negative terminal) 21b1 Negative terminal (negative terminal) 23, 23A Busbar cover (terminal insulation cover) 25 Space 31 Battery case 33 Upper cover (cover) 40 Water Jacket 42 Chiller (second heat exchanger) 51 Section 1 52 Section 2 60 Cover plate (terminal insulation cover) 83 Second branch (branch) 100 Battery Cooling System 212 Electrode tab (cell terminal) 523 Front gap (air passage) 524 Center front gap (air passage) 526 Center rear gap (air passage) 527 Rear gap (air passage)

Claims

1. a plurality of cells having positive and negative terminals; A plurality of battery modules each including a plurality of the cells stacked therein; a battery case that houses the plurality of battery modules; a water jacket disposed in or inside the battery case, through which a first coolant flows and through which the water jacket exchanges heat with the battery modules; a heat exchanger that is disposed in or inside the battery case and through which a second refrigerant flows and exchanges heat with the air inside; a fan disposed in or inside the battery case for circulating air therein.

2. 2. The battery pack according to claim 1, The water jacket cools the battery modules from below, The battery case includes: a first section in which the plurality of battery modules are arranged and heat exchange occurs between the plurality of battery modules and the water jacket; a second section above the water jacket, in which the plurality of battery modules are not disposed; a gap provided between the plurality of cells and an inner wall of the battery case, the gap allowing air to pass through.

3. 3. The battery pack according to claim 2, The battery case houses a junction box, The junction box is positioned such that air circulated between the first compartment and the second compartment by the fan comes into contact with a conductive member of the junction box.

4. 3. The battery pack according to claim 2, The second section is located outside the first section and on both sides of the first section, The heat exchanger and the fan are disposed in the second compartment.

5. 5. The battery pack according to claim 4, The fans are disposed in the second compartments, The second sections each include a positive pressure region on the side of the fan where air is exhausted from the fan; a negative pressure region on the side of the fan where the air is introduced into the fan; The positive pressure region of the second compartment on one side and the negative pressure region of the second compartment on the other side face each other across the first compartment, A battery pack, wherein the negative pressure region of the second compartment on one side and the positive pressure region of the second compartment on the other side face each other with the first compartment in between.

6. 2. The battery pack according to claim 1, The plurality of battery modules each have a terminal insulating cover that covers at least one of the positive terminal and the negative terminal of the cell, a space extending in a stacking direction of the cells is provided between the terminal insulating cover and the cell terminal.

7. 3. The battery pack according to claim 2, The second section is located outside the first section and on both sides of the first section, Between adjacent battery modules or between the battery module and the cross member, The battery pack further comprises an air passage formed perpendicular to the extension direction of the second compartment and connecting the second compartment on one side to the second compartment on the other side.

8. A battery pack according to any one of claims 1 to 7; a refrigerant circuit in which the first refrigerant circulates through the water jacket; a heat pump circuit in which the second refrigerant circulates through the heat exchanger; a second heat exchanger capable of exchanging heat between the first refrigerant and the second refrigerant; a control unit that controls the heat exchanger, the second heat exchanger, and the fan.

9. 9. The battery cooling system of claim 8, The control unit is When the temperature of the cell is higher than a first threshold, the second heat exchanger is controlled to an on state; When the terminal temperature of the cell is higher than a second threshold value, the heat exchanger and the fan are controlled to be in an on state. Battery cooling system.

10. 9. The battery cooling system of claim 8, The heat pump circuit has a branch portion to a flow path flowing to the heat exchanger, upstream of the flow path flowing to the second heat exchanger. Battery cooling system.

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