Battery System

Abstract

To provide a battery system which allows improvement in heat dissipation via external terminals of battery cells while avoiding contact between a coolant and members around electrodes of the battery cells, and which can facilitate electrical connection between the external terminals of the adjacent battery cells.SOLUTION: A battery system 100 comprises: a plurality of battery cells 1; a plurality of conductive bus bars 2, each having a hollow structure, which connect between external terminals 14 of adjacent ones of the plurality of battery cells 1; a plurality of insulation tubes 5, each having an electrical insulation property, which are provided between the plurality of bus bars 2; and a coolant path 3 which is formed inside the plurality of bus bars 2 and the plurality of insulation tubes 5 so as to circulate an electrical insulative coolant R for cooling the plurality of bus bars 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a battery system. [Background technology]

[0002] Battery packs including multiple battery cells have been known for some time. For example, the battery pack described in claims 1 and 7, FIG. 2, etc. of Patent Document 1 below has multiple battery cells housed in a case. The battery cells are formed in a rectangular parallelepiped shape. The case is filled with hydrofluoroether as an insulating coolant. The battery cells are also arranged so that the electrode side is located at the bottom of the case.

[0003] Also known is a cooling system for a lithium secondary battery that rapidly cools the lithium secondary battery. For example, the cooling system for a lithium secondary battery described in claims 5 and 6 and Figures 1 to 3 of Patent Document 2 below includes a conductive connector fixed to the electrode terminal of the lithium secondary battery, and a refrigerant pipe connected to the connector and through which a refrigerant flows. The conductive connector includes a body, a fixing portion formed on one side of the body and connected and fixed to the electrode terminal, and a connecting portion formed on the other side of the body and to which the refrigerant pipe is connected. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-062023 [Patent Document 2] Special Publication No. 2014-501024 Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional battery pack described in Patent Document 1, the electrodes of multiple battery cells are arranged so that they are located at the bottom of the case, and the electrodes of each battery cell are immersed in the insulating coolant (hydrofluoroether) filled in the case. As a result, there is a risk that unexpected side reactions may occur due to contact between the components around the electrodes of the battery cells and the insulating coolant.

[0006] The conventional cooling system for lithium secondary batteries described in Patent Document 2 can dissipate heat from the electrode terminals of each lithium secondary battery to the refrigerant pipe via the body of a conductive connector. However, the body of the conductive connector is a long, thin rod-shaped member that is connected to a portion of the side surface of the rectangular parallelepiped electrode terminal of each lithium secondary battery and to the lower end of the outer circumferential surface of the refrigerant pipe and extends in the radial direction of the refrigerant pipe, and therefore has a small cross-sectional area, posing a problem in terms of heat dissipation.

[0007] Furthermore, in the conventional cooling system for lithium secondary batteries, the conductive connector does not electrically connect the electrode terminals of adjacent lithium secondary batteries, and the configuration of the bus bar that electrically connects the electrode terminals is unclear. Therefore, depending on the configuration of the fasteners formed on one side of the body of the conductive connector and connected to the electrode terminals of each lithium secondary battery, electrical connection between the electrode terminals of adjacent lithium secondary batteries may be difficult.

[0008] The present disclosure provides a battery system that can improve heat dissipation through the external terminals of the battery cells while avoiding contact between the refrigerant and components around the electrode terminals of the battery cells, and can facilitate electrical connection between the external terminals of adjacent battery cells. [Means for solving the problem]

[0009] One aspect of the present disclosure is a battery system including: a plurality of battery cells; a plurality of conductive bus bars having a hollow structure that connect external terminals of adjacent battery cells of the plurality of battery cells; a plurality of insulating tubes that are provided between the plurality of bus bars and have electrical insulation; and refrigerant passages that are formed inside the plurality of bus bars and inside the plurality of insulating tubes and that circulate an electrically insulating refrigerant that cools the plurality of bus bars. [Effects of the Invention]

[0010] According to the above aspect of the present disclosure, it is possible to provide a battery system that can improve heat dissipation through the external terminals of the battery cells while avoiding contact between the refrigerant and components around the external terminals of the battery cells, and that can facilitate electrical connection between the external terminals of adjacent battery cells. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a partially cutaway side view of a first embodiment of a battery system according to the present disclosure. [Figure 2] FIG. 2 is a partially cutaway plan view of the battery system shown in FIG. [Figure 3] FIG. 2 is a perspective view of one battery cell of the battery system shown in FIG. [Figure 4] FIG. 10 is a partially cutaway side view of a battery system according to a second embodiment of the present disclosure. [Figure 5] FIG. 5 is a partially cutaway plan view of the battery system shown in FIG. [Figure 6] FIG. 5 is a block diagram of the battery system shown in FIG. [Figure 7] FIG. 10 is a partially cutaway side view of a battery system according to a third embodiment of the present disclosure. [Figure 8] FIG. 8 is a block diagram of the battery system shown in FIG. 7. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of a battery system according to the present disclosure will be described with reference to the drawings.

[0013] [Embodiment 1] Fig. 1 is a partially cut-away side view of a first embodiment of a battery system according to the present disclosure. Fig. 2 is a partially cut-away plan view of the battery system 100 shown in Fig. 1. Fig. 3 is a perspective view of one battery cell 1 of the battery system 100 shown in Fig. 1. The cross section of Fig. 1 is taken along line II in Fig. 2, and the cross section of Fig. 2 is taken along line II-II in Fig. 1. Each figure shows an orthogonal coordinate system consisting of an X-axis, a Y-axis, and a Z-axis that are parallel to the thickness, width, and height directions of the flattened rectangular parallelepiped battery cell 1, respectively.

[0014] The battery system 100 of this embodiment includes a plurality of battery cells 1, a plurality of conductive bus bars 2 that connect the external terminals 14 of adjacent battery cells 1 of the plurality of battery cells 1, and a refrigerant passage 3 that circulates an electrically insulating refrigerant R that cools the plurality of bus bars 2. The battery system 100 of this embodiment further includes, for example, a heat exchanger 4 connected to the refrigerant passage 3.

[0015] Although details will be described later, the battery system 100 of this embodiment is most characterized by the following configuration: The refrigerant passage 3 includes a bus bar passage 21 that penetrates each of the multiple bus bars 2, and an insulating passage 51 that is formed inside an electrically insulating insulating tube 5 and connects the bus bar passages 21 of adjacent bus bars 2 of the multiple bus bars 2. Each component of the battery system 100 of this embodiment will be described in detail below.

[0016] The battery cell 1 is, for example, a rectangular lithium-ion secondary battery. The type of battery cell 1 is not limited to a lithium-ion secondary battery, and may be, for example, a lead-acid battery, a nickel-metal hydride battery, or a nickel-cadmium battery. The battery cell 1 includes, for example, a flattened rectangular parallelepiped battery container 10, as shown in FIG. 3.

[0017] The battery container 10 is made of a metal such as an aluminum alloy, and is composed of a battery can 11 in the shape of a rectangular cylinder with a bottom, and a battery lid 12 that seals the opening at the top end of the battery can 11. Although not shown, the interior of the battery container 10 contains an electrode group formed by stacking and winding a strip-shaped positive electrode and a strip-shaped negative electrode with a strip-shaped separator interposed therebetween, a pair of current collector plates connected to the positive electrode and the negative electrode at both ends of the electrode group, an electrical insulating member, an electrolyte, and the like.

[0018] The battery container 10 has a pair of wide side surfaces 10w on both sides in the thickness direction (X-axis direction), a pair of narrow side surfaces 10n on both sides in the width direction (Y-axis direction), a bottom surface 10b at the lower end in the height direction (Z-axis direction), and a top surface 10t at the upper end in the height direction. Of these surfaces of the battery container 10, the wide side surfaces 10w have the largest area. A pair of external terminals 14 are arranged on the top surface 10t of the battery container 10 at both ends in the width direction of the battery container 10 via a pair of insulating members 13, and a split valve 15 and a liquid injection port 16 are provided between the pair of external terminals 14.

[0019] Of the pair of external terminals 14, one external terminal 14 is a positive electrode external terminal 14P connected to the positive electrode via a current collector, and the other external terminal 14 is a negative electrode external terminal 14N connected to the negative electrode via a current collector. The split valve 15 splits when the pressure inside the battery container 10 increases abnormally, ensuring the safety of the battery cell 1. The liquid filling port 16 is used to fill the electrolyte into the battery container 10 and is sealed with a liquid filling tap 17.

[0020] 2, the multiple battery cells 1 are arranged in an alternately inverted manner so that the positive electrode external terminal 14P of one adjacent battery cell 1 and the negative electrode external terminal 14N of the other adjacent battery cell 1 are adjacent in the thickness direction (X-axis direction) of the battery cell 1. Furthermore, the positive electrode external terminal 14P of one adjacent battery cell 1 and the negative electrode external terminal 14N of the other adjacent battery cell 1 are sequentially connected by bus bars 2, thereby connecting the multiple battery cells 1 in series.

[0021] In the plurality of battery cells 1 connected in series, an end bus bar 2E is connected to the positive external terminal 14P of the battery cell 1 at one end in the arrangement direction (X-axis direction) and to the negative external terminal 14N of the battery cell 1 at the other end in the arrangement direction. These end bus bars 2E function as external terminals of a battery group, which is a plurality of battery cells 1 connected in series by a plurality of bus bars 2.

[0022] As described above, the busbar 2 is a hollow, electrically conductive member that connects the external terminals 14 of adjacent battery cells 1 among the multiple battery cells 1. More specifically, the busbar 2 and the end busbar 2E are tubular metal members with good electrical and thermal conductivity. Examples of materials that can be used for the busbar 2 and the end busbar 2E include copper, aluminum, and nickel.

[0023] In this embodiment, the cross-sectional shape of the busbar 2 and the end busbar 2E is, for example, rectangular. The width of the busbar 2 and the end busbar 2E is, for example, approximately equal to the width of the external terminal 14 of the battery cell 1. The busbar 2 and the end busbar 2E are joined to the top surface of the external terminal 14 of the battery cell 1 by, for example, laser welding, and are connected to the external terminal 14.

[0024] The busbar passages 21 are hollow portions provided in the busbar 2 and the end busbar 2E. The busbar passages 21 have openings at one and the other longitudinal ends of the busbar 2 and the end busbar 2E, respectively, and penetrate the busbar 2 and the end busbar 2E. In this embodiment, the cross-sectional shape of the busbar passages 21 is rectangular, similar to the busbar 2 and the end busbar 2E.

[0025] The insulating tube 5 is an electrically insulating tube made of, for example, an electrically insulating resin material. The insulating passage 51 is a hollow portion provided in the insulating tube 5, has openings at one end and the other end of the insulating tube 5, and passes through the insulating tube 5. In this embodiment, the cross-sectional shape of the insulating tube 5 and the insulating passage 51 is rectangular, similar to the cross-sectional shape of the bus bar 2 and the bus bar passage 21.

[0026] The insulating pipes 5 are arranged between adjacent bus bars 2 in the arrangement direction of the battery cells 1 (X-axis direction), and connect the bus bar passages 21 of those bus bars 2 via insulating passages 51. The insulating pipes 5 also connect, for example, one of the pair of refrigerant outlets 43 of the heat exchanger 4 to the bus bar passage 21 of the bus bar 2 closest to the heat exchanger 4. The insulating pipes 5 also connect, for example, the other of the pair of refrigerant outlets 43 of the heat exchanger 4 to the bus bar passage 21 of the end bus bar 2E closest to the heat exchanger 4.

[0027] The insulating tube 5 connects, for example, one of the pair of refrigerant inlets 41 of the heat exchanger 4 to the bus bar passage 21 of the bus bar 2 that is farthest from the heat exchanger 4. The insulating tube 5 also connects, for example, the other of the pair of refrigerant inlets 41 of the heat exchanger 4 to the bus bar passage 21 of the end bus bar 2E that is farthest from the heat exchanger 4.

[0028] The refrigerant passage 3 is a passage for circulating an electrically insulating refrigerant R that cools the multiple bus bars 2 and the end bus bars 2E. The boiling point of the refrigerant R at atmospheric pressure is, for example, within a range of 0°C to 55°C. As the refrigerant R, for example, a fluorine-based solvent such as hydrofluoroether can be used. The internal pressure of the refrigerant passage 3 can also be reduced to a pressure lower than atmospheric pressure.

[0029] The refrigerant passage 3 is made up of, for example, a plurality of busbar passages 21 for the plurality of busbars 2 and end busbars 2E, and a plurality of insulating passages 51 for the plurality of insulating tubes 5. A refrigerant R that cools the plurality of busbars 2 and end busbars 2E is sealed inside the refrigerant passage 3. The refrigerant passage 3 is connected to, for example, a heat exchanger 4, and circulates the refrigerant R between the heat exchanger 4 and the plurality of busbars 2 and end busbars 2E.

[0030] The refrigerant passage 3 has, for example, a first refrigerant passage 31, a second refrigerant passage 32, and a third refrigerant passage 33. The first refrigerant passage 31 is connected to a refrigerant outlet 43 of the heat exchanger 4 and extends horizontally. The second refrigerant passage 32 extends vertically upward from the first refrigerant passage 31. The third refrigerant passage 33 is connected to the upper end of the second refrigerant passage 32, extends horizontally, and is connected to a refrigerant inlet 41 of the heat exchanger 4.

[0031] For example, the refrigerant R fills the entire first refrigerant passage 31, and has a liquid level below the upper end of the second refrigerant passage 32. Note that the refrigerant R may also fill the first refrigerant passage 31 partially, and have a liquid level within the first refrigerant passage 31.

[0032] The heat exchanger 4 is disposed, for example, above the first refrigerant passage 31 including the bus bar passage 21. The heat exchanger 4 has, for example, a refrigerant inlet 41, a heat dissipation portion 42, and a refrigerant outlet 43.

[0033] 2, the heat exchanger 4 has a pair of refrigerant inlets 41 spaced apart in the width direction (Y-axis direction) of the battery cell 1 at the upper end of the heat dissipation section 42. The heat exchanger 4 also has a pair of refrigerant outlets 43 spaced apart in the width direction of the battery cell 1 at the lower end of the heat dissipation section 42. The pair of refrigerant outlets 43 are connected to the starting ends of the pair of refrigerant passages 3, and the pair of refrigerant inlets 41 are connected to the ending ends of the pair of refrigerant passages 3.

[0034] Heat dissipation unit 42 dissipates heat from refrigerant R to the outside air while passing refrigerant R introduced from refrigerant inlet 41 downward. More specifically, heat dissipation unit 42 has a serpentine flow path 42a that guides refrigerant R downward in the vertical direction while serpentinely moving back and forth along the horizontal direction. Heat dissipation unit 42 also has, for example, a heat sink 42b including a plurality of heat dissipation fins.

[0035] The operation of the battery system 100 of this embodiment will be described below.

[0036] The battery system 100 of this embodiment can supply power from an external generator or the like to a battery group including a plurality of battery cells 1 connected in series by a plurality of bus bars 2, via a pair of end bus bars 2E that function as external terminals of the battery group. This allows the plurality of battery cells 1 in the battery system 100 to be charged.

[0037] Furthermore, the battery system 100 can supply power to an external device such as a motor from the multiple charged battery cells 1 via a pair of end bus bars 2E. In the battery system 100, it is important to uniformly cool each battery cell 1 in order to maintain the temperature of the multiple battery cells 1, which rise due to charging and discharging, within an appropriate temperature range and suppress deterioration of each battery cell 1.

[0038] As described above, the battery system 100 of this embodiment includes a plurality of battery cells 1, a plurality of bus bars 2, a plurality of insulating tubes 5, and a refrigerant passage 3. Each of the plurality of bus bars 2 connects the external terminals 14 of adjacent battery cells 1 of the plurality of battery cells 1 and is a conductive member with a hollow structure. Each of the plurality of insulating tubes 5 is provided between adjacent bus bars 2 of the plurality of bus bars 2 and has electrical insulation properties. The refrigerant passage 3 is formed inside the plurality of bus bars 2 and inside the plurality of insulating tubes 5, and circulates an electrically insulating refrigerant R that cools the plurality of bus bars 2. More specifically, the refrigerant passage 3 includes a bus bar passage 21 that penetrates each of the plurality of bus bars 2 and an insulating passage 51 that is formed inside the electrically insulating insulating tube 5 and connects the bus bar passages 21 of adjacent bus bars 2 of the plurality of bus bars 2.

[0039] With this configuration, the battery system 100 of this embodiment differs from the battery pack described in Patent Document 1 in that the refrigerant R is sealed in the refrigerant passage 3, preventing contact between the refrigerant R and peripheral members of the external terminals 14 of each battery cell 1. Therefore, the battery system 100 of this embodiment can prevent unexpected side reactions from occurring due to contact between the refrigerant R and peripheral members of the external terminals 14 of each battery cell 1. Furthermore, the battery system 100 of this embodiment circulates the refrigerant R through the refrigerant passage 3, thereby reducing the amount of refrigerant R required to cool the multiple battery cells 1 compared to the conventional battery pack, thereby enabling cost reductions for the refrigerant R.

[0040] Furthermore, with the above configuration, the battery system 100 of this embodiment can cool each bus bar 2 using the refrigerant R circulating through the bus bar passage 21 inside each bus bar 2, and can cool the external terminals 14 of each battery cell 1 using each bus bar 2. Furthermore, each bus bar 2 can have a larger bonding area with respect to the external terminals 14 of the battery cell 1 compared to the conductive connectors in the conventional cooling system for a lithium secondary battery described in Patent Document 2. Therefore, the battery system 100 of this embodiment can improve heat dissipation via the external terminals 14 of each battery cell 1 compared to the conventional cooling system.

[0041] Furthermore, in the conventional cooling system, the electrode terminals of the lithium secondary batteries are not directly cooled by refrigerant pipes cooled by a refrigerant, but are indirectly cooled via conductive connectors cooled by the refrigerant pipes. In contrast, in the battery system 100 of the present embodiment, the busbars 2 cooled by the refrigerant R in the busbar passages 21 that penetrate the busbars 2 directly cool the external terminals 14 of the battery cells 1 due to the above-described configuration. Therefore, the battery system 100 of the present embodiment improves heat dissipation via the external terminals 14 of each battery cell 1, suppresses deterioration of each external terminal 14, and extends the service life of the external terminals 14 compared to the conventional cooling system.

[0042] Additionally, in the conventional cooling system, it is necessary to join bus bars to the electrode terminals in addition to the conductive connectors and refrigerant pipes that cool the electrode terminals of the lithium secondary batteries. In contrast, in the battery system 100 of the present embodiment, the above-described configuration allows the refrigerant passage 3, which circulates the refrigerant that cools each bus bar 2, to include bus bar passages 21 that penetrate each bus bar 2. Therefore, the refrigerant passage 3 is formed by the bus bar passages 21 of the multiple bus bars 2 and the insulating passages 51 of the multiple insulating pipes 5, and at the same time, the external terminals 14 of adjacent battery cells 1 of the multiple battery cells 1 can be electrically connected by the bus bars 2. Therefore, the battery system 100 of the present embodiment makes it easier to electrically connect the external terminals 14 of adjacent battery cells 1 than in the conventional cooling system.

[0043] The battery system 100 of this embodiment also includes a heat exchanger 4 connected to the refrigerant passage 3. The heat exchanger 4 has a refrigerant inlet 41, a heat dissipation section 42, and a refrigerant outlet 43. The refrigerant inlet 41 is connected to the end of the refrigerant passage 3. The heat dissipation section 42 dissipates heat from the refrigerant R to the outside air while allowing the refrigerant R introduced from the refrigerant inlet 41 to pass downward. The refrigerant outlet 43 is provided at the lower end of the heat dissipation section 42 and is connected to the start of the refrigerant passage 3.

[0044] With this configuration, in the battery system 100 of this embodiment, the refrigerant R, whose temperature has increased by cooling the battery cells 1 via the multiple bus bars 2, is introduced from the end of the refrigerant passage 3 to the refrigerant inlet 41 of the heat exchanger 4. The refrigerant R introduced into the refrigerant inlet 41 passes downward through the heat dissipation section 42, and its temperature is reduced by dissipating heat into the outside air via the heat dissipation section 42. The refrigerant R whose temperature has been reduced is introduced by gravity from the lower end of the heat dissipation section 42 to the start of the refrigerant passage 3, and cools each battery cell 1 via each bus bar 2. Therefore, the battery system 100 of this embodiment does not require a pump to circulate the refrigerant R through the refrigerant passage 3, making it possible to improve reliability and reduce power consumption.

[0045] Furthermore, in the battery system 100 of this embodiment, the refrigerant passage 3 has a first refrigerant passage 31, a second refrigerant passage 32, and a third refrigerant passage 33. The first refrigerant passage 31 is connected to a refrigerant outlet 43 of the heat exchanger 4 and extends horizontally. The second refrigerant passage 32 extends vertically upward from the first refrigerant passage 31. The third refrigerant passage 33 is connected to the upper end of the second refrigerant passage 32, extends horizontally, and is connected to a refrigerant inlet 41 of the heat exchanger 4.

[0046] With this configuration, the battery system 100 of this embodiment can efficiently cool multiple battery cells 1 simultaneously using the refrigerant R in the first refrigerant passage 31 via the multiple bus bars 2. Furthermore, the refrigerant R whose temperature has risen in the first refrigerant passage 31 moves from the first refrigerant passage 31 to the second refrigerant passage 32 extending vertically upward. This prevents backflow and abnormal temperature rise of the refrigerant R due to bumping of the refrigerant R in the first refrigerant passage 31, and prevents a decrease in the cooling efficiency of the battery cells 1.

[0047] Furthermore, in the battery system 100 of this embodiment, the heat exchanger 4 is disposed above the first refrigerant passage 31 of the refrigerant passage 3. With this configuration, the battery system 100 of this embodiment can more efficiently circulate the refrigerant R between the refrigerant passage 3 and the heat exchanger 4 by the action of gravity.

[0048] Furthermore, in the battery system 100 of this embodiment, the boiling point of the refrigerant R at atmospheric pressure is in the range of 0°C to 55°C. With this configuration, at least a portion of the liquid refrigerant R in the refrigerant passage 3 that cools the external terminals 14 of the battery cells 1 via the busbar 2 boils and evaporates. The heat of vaporization of the refrigerant R can further improve the cooling efficiency of the battery cells 1. Furthermore, the battery cells 1 with temperatures higher than the boiling point of the refrigerant R are preferentially cooled, making it possible to make the temperature of the multiple battery cells 1 uniform. Furthermore, by adopting a boiling cooling method using the refrigerant R, the cooling efficiency of the battery cells 1 can be improved compared to air-cooling and water-cooling methods.

[0049] Furthermore, the refrigerant R that has evaporated after cooling the battery cells 1 in the refrigerant passage 3 is cooled in the heat dissipation section 42 and condenses back into liquid. The refrigerant R that has returned to liquid in the heat dissipation section 42 is cooled as it flows downward within the heat dissipation section 42 due to the action of gravity, and is then introduced into the refrigerant passage 3 from the refrigerant outlet 43. This allows the refrigerant R to circulate more efficiently between the refrigerant passage 3 and the heat exchanger 4.

[0050] In the battery system 100 of this embodiment, the refrigerant R is a hydrofluoroether. This allows the boiling point of the refrigerant R at atmospheric pressure to be within a range from 0°C to 55°C, more specifically, approximately 54°C. Furthermore, the electrical insulation required for the refrigerant R can be sufficiently ensured.

[0051] Furthermore, in the battery system 100 of this embodiment, when the internal pressure of the refrigerant passage 3 is lower than atmospheric pressure, the boiling point of the refrigerant R can be further reduced. Therefore, the boiling point of the refrigerant R can be optimized according to the characteristics of the battery cells 1, and the cooling efficiency of the battery cells 1 by the refrigerant R via the bus bars 2 can be further improved.

[0052] As described above, according to this embodiment, it is possible to provide a battery system 100 that can improve heat dissipation through the external terminals 14 of the battery cells 1 while avoiding contact between the refrigerant R and components around the external terminals 14 of the battery cells 1, and that can facilitate electrical connection between the external terminals 14 of adjacent battery cells 1.

[0053] [Embodiment 2] A second embodiment of a battery system according to the present disclosure will be described below with reference to Fig. 4 to Fig. 6. Fig. 4 is a partially cutaway side view of the second embodiment of a battery system according to the present disclosure. Fig. 5 is a partially cutaway plan view of the battery system 100A shown in Fig. 4. Fig. 6 is a block diagram of the battery system 100A shown in Fig. 4.

[0054] The cross section in Fig. 4 is taken along line IV-IV in Fig. 5, and the cross section in Fig. 5 is taken along line VV in Fig. 4. Fig. 4 also shows a cross section of first refrigerant passage 31, second refrigerant passage 32, and third refrigerant passage 33, including bus bar 2A located on the negative side of the Y axis, and omits illustration of these components located on the positive side of the Y axis.

[0055] The battery system 100A of this embodiment differs from the battery system 100 of the first embodiment in the following configuration, for example. The battery system 100A of this embodiment further includes a flow rate sensor 7, a temperature sensor 8, and a control device 9. In the battery system 100A of this embodiment, the refrigerant passage 3A has a circular cross section. The bus bar 2A has a branch portion 22 and is connected to the external terminals 14 of the battery cells 1 via the plate-shaped members 6.

[0056] Furthermore, in the battery system 100A of this embodiment, for example, the first refrigerant passages 31 on both sides in the width direction (Y-axis direction) of the battery cells 1 that make up the refrigerant passage 3A are connected by insulating tubes 5 at the ends opposite the heat exchanger 4 in the arrangement direction (X-axis direction) of the battery cells 1. The other configurations of the battery system 100A of this embodiment are similar to those of the battery system 100 of the first embodiment described above, and therefore similar parts are denoted by the same reference numerals and description thereof will be omitted.

[0057] In the battery system 100A of the present embodiment, as described above, the cross-sectional shape of the refrigerant passage 3A is circular, and therefore the cross-sectional shapes of the bus bar 2A and the insulating tube 5 are also circular, and the shapes of the refrigerant inlet 41 and the refrigerant outlet 43 of the heat exchanger 4 are also circular. The materials of the bus bar 2A and the plate-like member 6 are the same as those of the bus bar 2 and the end bus bar 2E of the first embodiment.

[0058] The busbar 2A has, for example, a T-shape with branch sections 22 that branch off at right angles from the center of a straight pipe section. The branch sections 22 of each busbar 2A are arranged, for example, to face upward, in the direction opposite the external terminals 14 of the battery cells 1. The upper end of each branch section 22 is connected to the lower end of an insulating tube 5 that extends vertically.

[0059] The upper ends of the insulating pipes 5, which are connected to the branch portions 22 of the bus bars 2A and extend vertically, are connected to insulating pipes 5 extending horizontally. The bus bar passages 21 passing through the branch portions 22 of the multiple bus bars 2A and the insulating passages 51 of the multiple insulating pipes 5 form multiple second refrigerant passages 32 extending vertically upward from the first refrigerant passage 31.

[0060] That is, the refrigerant passage 3A has a plurality of second refrigerant passages 32 extending in the vertical direction between a first refrigerant passage 31 connected to the refrigerant outlet 43 of the heat exchanger 4 and extending in the horizontal direction, and a third refrigerant passage 33 connected to the refrigerant inlet 41 of the heat exchanger 4 and extending in the horizontal direction.

[0061] The flow rate sensor 7 detects the flow rate of the refrigerant R flowing through the third refrigerant passage 33 of the refrigerant passage 3A. More specifically, the flow rate sensor 7 is attached to the third refrigerant passage 33 between the plurality of second refrigerant passages 32 and the refrigerant inlet 41 of the heat exchanger 4, for example, and detects the flow rate of the vapor of the refrigerant R that evaporates as its temperature increases by cooling the battery cells 1. The flow rate sensor 7 outputs the detected flow rate of the refrigerant R to the control device 9.

[0062] The temperature sensor 8 detects the temperature of at least one of the plurality of battery cells 1. For example, as shown in FIG. 5 , the temperature sensor 8 is attached to the top surface 10t of one battery cell 1 that is arranged in the center of the plurality of battery cells 1 that are arranged in the thickness direction. Note that the temperature sensor 8 may be attached to each battery cell 1. The temperature sensor 8 outputs the detected temperature of the battery cell 1 to the control device 9.

[0063] The control device 9 is configured, for example, by one or more microcontrollers, and controls a battery pack made up of multiple electrically connected battery cells 1. As shown in Fig. 6, the control device 9 has, for example, a boiling detection unit 91, a load limiting unit 92, and a charge / discharge control unit 93. Each of these units of the control device 9 represents a function of the control device 9 that is realized, for example, by the central processing unit (CPU) of the control device 9 executing a program stored in the memory of the control device 9.

[0064] The boiling detection unit 91 detects transition boiling of the refrigerant R based on the flow rate of the refrigerant R detected by the flow rate sensor 7 and the temperature of at least one battery cell 1 detected by the temperature sensor 8. More specifically, the boiling detection unit 91 detects transition boiling of the refrigerant R, for example, when the detected flow rate of the refrigerant R and the temperature of the battery cell 1 satisfy transition boiling conditions stored in advance in memory. Note that the boiling detection unit 91 may detect transition boiling of the refrigerant R using either the detected flow rate of the refrigerant R or the temperature of the battery cell 1.

[0065] When the boiling detection unit 91 detects transition boiling of the refrigerant R, the load limiting unit 92 calculates an upper limit power for limiting the power load of the battery pack including the plurality of battery cells 1. The charge / discharge control unit 93 controls the charge / discharge of the plurality of battery cells 1 based on the upper limit power calculated by the load limiting unit 92.

[0066] The operation of the battery system 100A of this embodiment will be described below.

[0067] In the battery system 100A of this embodiment, the refrigerant passage 3A has a first refrigerant passage 31 that extends horizontally and is connected to a refrigerant outlet 43 of the heat exchanger 4, and a plurality of second refrigerant passages 32 that extend vertically upward from the first refrigerant passage 31. The upper ends of the plurality of second refrigerant passages 32 are connected to third refrigerant passages 33 that are connected to a refrigerant inlet 41 of the heat exchanger 4 and extend horizontally.

[0068] With this configuration, the refrigerant R that boils and vaporizes in the first refrigerant passage 31 can be released into the third refrigerant passage 33 via the multiple second refrigerant passages 32, introduced into the refrigerant inlet 41 of the heat exchanger 4 through the third refrigerant passage 33, and condensed in the heat dissipation section 42 of the heat exchanger 4. Therefore, the battery system 100A of this embodiment can promote the circulation of the refrigerant R in the refrigerant passage 3A and improve heat dissipation via the external terminals 14 of the battery cells 1.

[0069] Furthermore, in the battery system 100A of this embodiment, each bus bar 2A is connected to the external terminal 14 of the battery cell 1 via a plate-shaped member 6. With this configuration, the battery system 100A of this embodiment can easily join the bus bar 2A to the external terminal 14 of the battery cell 1, and can easily electrically connect the external terminals 14 of adjacent battery cells 1.

[0070] The battery system 100A of this embodiment also includes a flow rate sensor 7 that detects the flow rate of the refrigerant R flowing through the third refrigerant passage 33, a temperature sensor 8 that detects the temperature of at least one battery cell 1 among the multiple battery cells 1, and a control device 9 that controls the multiple battery cells 1. The control device 9 includes a boiling detection unit 91, a load limiting unit 92, and a charge / discharge control unit 93. The boiling detection unit 91 detects transition boiling of the refrigerant R based on the flow rate of the refrigerant R detected by the flow rate sensor 7 and the temperature of at least one battery cell 1 detected by the temperature sensor 8. The load limiting unit 92 calculates an upper limit power for limiting the power load of the multiple battery cells 1 when transition boiling of the refrigerant R is detected by the boiling detection unit 91. The charge / discharge control unit 93 controls charging / discharging of the multiple battery cells 1 based on the upper limit power calculated by the load limiting unit 92.

[0071] With this configuration, when the boiling detection unit 91 of the control device 9 detects transition boiling of the refrigerant R, the battery system 100A of this embodiment limits the power load of the multiple battery cells 1, thereby maintaining nucleate boiling of the refrigerant R. Therefore, the battery system 100A of this embodiment can improve heat dissipation through the external terminals 14 of the battery cells 1 due to boiling of the refrigerant R.

[0072] As described above, according to this embodiment, it is possible to provide a battery system 100A that can improve the heat dissipation performance of the battery cell 1 through the battery cell 1 while avoiding contact between the refrigerant R and the components around the external terminals 14 of the battery cell 1, and that can facilitate electrical connection between the external terminals 14 of adjacent battery cells 1.

[0073] [Embodiment 3] A third embodiment of a battery system according to the present disclosure will be described below with reference to Fig. 7 and Fig. 8. Fig. 7 is a partially cutaway side view of the third embodiment of a battery system according to the present disclosure. Fig. 8 is a block diagram of the battery system 100B shown in Fig. 7.

[0074] The battery system 100B of this embodiment differs from the battery system 100A of the second embodiment in the following configuration, for example. The battery system 100B includes a coolant passage T1 that supplies coolant L to the outer surface of the heat dissipation section 42 of the heat exchanger 4, and a solenoid valve V that opens and closes the coolant passage T1. In addition, the battery system 100B of this embodiment includes a control device 9 that includes a solenoid valve control section 94. The battery system 100B of this embodiment also includes a housing C. The other configurations of the battery system 100B of this embodiment are similar to those of the battery system 100A of the second embodiment, and therefore similar parts are denoted by the same reference numerals and description thereof will be omitted.

[0075] The coolant passage T1 is, for example, a coolant supply pipe connected to a coolant tank T that stores coolant L, and supplies the coolant L from the coolant tank T to the outer surface of the heat dissipation unit 42 of the heat exchanger 4. The coolant passage T1 is, for example, disposed above the heat sink 42b of the heat dissipation unit 42, extends vertically downward from the coolant tank T, and has an opening at its tip located near the heat sink 42b. The coolant L can be, for example, water.

[0076] The solenoid valve V is provided, for example, in the coolant passage T1 between the coolant tank T and the heat exchanger 4. The solenoid valve V includes, for example, a valve element that opens and closes the coolant passage T1, and a drive unit that drives the valve element. The solenoid valve V opens and closes the coolant passage T1 when the drive unit, controlled by the control device 9, drives the valve element.

[0077] The control device 9 has a boiling detection unit 91 and a solenoid valve control unit 94 that opens the solenoid valve V when transition boiling of the refrigerant R is detected by the boiling detection unit 91. Note that the control device 9 may also have a load limiting unit 92 and a charge / discharge control unit 93, and control an assembled battery including a plurality of battery cells 1, similar to the battery system 100A of the second embodiment shown in FIG.

[0078] The housing C houses multiple battery cells 1, multiple bus bars 2A, and refrigerant passages 3A. More specifically, the housing C is shaped like a rectangular parallelepiped and houses multiple insulating tubes 5 and a heat exchanger 4, along with the multiple battery cells 1, multiple bus bars 2A, and refrigerant passages 3A, and includes a thermal insulator. More specifically, the housing C has a thermal insulator bonded to at least one of the inner and outer surfaces of a main body made of metal or resin, for example. The housing C also has an opening C1 that exposes the heat sink 42b of the heat dissipation unit 42 to the outside, for example.

[0079] The operation of the battery system 100B of this embodiment will be described below.

[0080] As described above, the battery system 100B of this embodiment includes the flow sensor 7, the temperature sensor 8, the coolant passage T1, the solenoid valve V, and the control device 9. The flow sensor 7 detects the flow rate of the refrigerant R flowing through the third refrigerant passage 33 of the refrigerant passage 3A. The temperature sensor 8 detects the temperature of at least one battery cell 1 among the multiple battery cells 1. The coolant passage T1 supplies the coolant L to the outer surface of the heat dissipation section 42 of the heat exchanger 4. The solenoid valve V opens and closes the coolant passage T1. The control device 9, which controls the solenoid valve V, includes a boiling detection unit 91 and a solenoid valve control unit 94. The boiling detection unit 91 detects transition boiling of the refrigerant R based on the flow rate of the refrigerant R detected by the flow sensor 7 and the temperature of at least one battery cell 1 detected by the temperature sensor 8. The solenoid valve control unit 94 opens the solenoid valve V when transition boiling of the refrigerant R is detected by the boiling detection unit 91.

[0081] With this configuration, when the boiling detection unit 91 of the control device 9 detects transition boiling of the refrigerant R, the battery system 100B of this embodiment opens the solenoid valve V to supply the coolant L from the coolant passage T1 to the outer surface of the heat dissipation unit 42 of the heat exchanger 4. As a result, the cooling performance of the refrigerant R by the heat dissipation unit 42 is improved, and nucleate boiling of the refrigerant R can be maintained. Therefore, according to the battery system 100B of this embodiment, similar to the battery system 100A of the second embodiment, it is possible to improve heat dissipation via the external terminals 14 of the battery cells 1 due to boiling of the refrigerant R. Furthermore, by using water as the coolant L, it is possible to eliminate the impact of evaporated coolant L on the environment.

[0082] The battery system 100B of this embodiment also includes a housing C. The housing C includes a thermal insulator and houses the multiple battery cells 1, the multiple bus bars 2A, and the refrigerant passages 3A. With this configuration, for example, when the battery system 100B is mounted on a vehicle, even at night when the vehicle is parked and the battery system 100B is idle, it is possible to prevent the temperature of the refrigerant R from dropping too low, thereby preventing lithium deposition in each battery cell 1. It also makes it possible to eliminate the need for warm-up operation of the vehicle.

[0083] As described above, according to this embodiment, it is possible to provide a battery system 100B that can improve heat dissipation through the external terminals 14 of the battery cells 1 while avoiding contact between the refrigerant R and components around the external terminals 14 of the battery cells 1, and that can facilitate electrical connection between the external terminals 14 of adjacent battery cells 1.

[0084] The above has described in detail an embodiment of the battery system according to the present disclosure using the drawings, but the specific configuration is not limited to this embodiment, and even if there are design changes, etc., within the scope that does not deviate from the gist of the present disclosure, they are included in the present disclosure. [Explanation of symbols]

[0085] 1 battery cell 14 External terminal 2 busbars 2A busbar 2E End busbar (busbar) 21 Busbar passage 3 Refrigerant passage 3A Refrigerant passage 31 First refrigerant passage 32 Second refrigerant passage 33 Third refrigerant passage 4 Heat exchanger 41 Refrigerant inlet 42 Heat dissipation part 43 Refrigerant outlet 5. Insulating tube 51 Insulated Passage 7 Flow Sensor 8 Temperature Sensor 9 Control Device 91 Boiling detection unit 92 Load Limiting Section 93 Charge / discharge control unit 94 Solenoid valve control section 100 Battery System 100A battery system 100B Battery System C chassis R refrigerant T1 coolant passage V solenoid valve

Claims

1. A plurality of battery cells; a plurality of conductive bus bars having hollow structures that connect the external terminals of adjacent battery cells of the plurality of battery cells; a plurality of insulating tubes provided between the plurality of bus bars and having electrical insulation properties; a refrigerant passage formed inside the plurality of bus bars and inside the plurality of insulating pipes, the refrigerant passage circulating an electrically insulating refrigerant for cooling the plurality of bus bars; a heat exchanger connected to the refrigerant passage, the heat exchanger including: a refrigerant inlet connected to an end of the refrigerant passage; a heat radiating section that radiates heat of the refrigerant to outside air while passing the refrigerant introduced from the refrigerant inlet downward; and a refrigerant outlet provided at a lower end of the heat radiating section and connected to a starting end of the refrigerant passage; Equipped with The refrigerant passage includes a first refrigerant passage connected to the refrigerant outlet and extending horizontally, a second refrigerant passage extending vertically upward from the first refrigerant passage, and a third refrigerant passage connected to an upper end of the second refrigerant passage, extending horizontally, and connected to the refrigerant inlet. and moreover, a flow rate sensor for detecting a flow rate of the refrigerant flowing through the third refrigerant passage; a temperature sensor for detecting a temperature of at least one of the plurality of battery cells; a control device that controls the plurality of battery cells; Equipped with The control device a boiling detection unit that detects transition boiling of the refrigerant based on the flow rate of the refrigerant detected by the flow rate sensor and the temperature of the at least one battery cell detected by the temperature sensor; a load limiting unit that calculates an upper limit power for limiting the power load of the plurality of battery cells when transition boiling of the refrigerant is detected by the boiling detection unit; a charge / discharge control unit that controls charging / discharging of the plurality of battery cells based on the upper limit power calculated by the load limiting unit; A battery system comprising:

2. A plurality of battery cells; a plurality of conductive bus bars having hollow structures that connect the external terminals of adjacent battery cells of the plurality of battery cells; a plurality of insulating tubes provided between the plurality of bus bars and having electrical insulation properties; a refrigerant passage formed inside the plurality of bus bars and inside the plurality of insulating pipes, the refrigerant passage circulating an electrically insulating refrigerant for cooling the plurality of bus bars; a heat exchanger connected to the refrigerant passage, the heat exchanger including: a refrigerant inlet connected to an end of the refrigerant passage; a heat radiating section that radiates heat of the refrigerant to outside air while passing the refrigerant introduced from the refrigerant inlet downward; and a refrigerant outlet provided at a lower end of the heat radiating section and connected to a starting end of the refrigerant passage; Equipped with The refrigerant passage includes a first refrigerant passage connected to the refrigerant outlet and extending horizontally, a second refrigerant passage extending vertically upward from the first refrigerant passage, and a third refrigerant passage connected to an upper end of the second refrigerant passage, extending horizontally, and connected to the refrigerant inlet. and moreover, a flow rate sensor for detecting a flow rate of the refrigerant flowing through the third refrigerant passage; a temperature sensor for detecting a temperature of at least one of the plurality of battery cells; a coolant passage for supplying a coolant to an outer surface of the heat radiating portion of the heat exchanger; an electromagnetic valve that opens and closes the coolant passage; a control device for controlling the solenoid valve; Equipped with The control device a boiling detection unit that detects transition boiling of the refrigerant based on the flow rate of the refrigerant detected by the flow rate sensor and the temperature of the at least one battery cell detected by the temperature sensor; a solenoid valve control unit that opens the solenoid valve when transition boiling of the refrigerant is detected by the boiling detection unit; A battery system comprising:

3. 3. The battery system according to claim 1, wherein the heat exchanger is disposed above the first refrigerant passage.

4. 3. The battery system according to claim 1, wherein the boiling point of the refrigerant at atmospheric pressure is in the range of 0°C to 55°C.

5. 3. The battery system according to claim 1, wherein the refrigerant is a hydrofluoroether.

6. 3. The battery system according to claim 1, wherein the internal pressure of the refrigerant passage is lower than atmospheric pressure.

7. 3. The battery system according to claim 1, further comprising a housing containing a heat insulating material and accommodating the plurality of battery cells, the plurality of bus bars, and the coolant passage.

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