Power supply device

Abstract

The present invention provides a power supply device which has enhanced safety.　A power supply device (100) according to the present invention is provided with: a plurality of secondary battery cells (1), each of which is provided with a positive electrode (2) on one end face, the positive electrode having a safety valve; a battery holder which holds the plurality of secondary battery cells (1), each having the positive electrode (2) on one end face, in upright postures so as to be parallel to each other, with the positive electrodes (2) facing vertically downward; and a case (20) that has a bottom surface (22) and a top surface (23) in the internal space in which the battery holder is contained. The battery holder is maintained within the case (20) in such a manner that the positive electrodes (2) of the secondary battery cells (1) are at a distance from the bottom surface (22), thereby forming a first space (SP1) therebetween. Due to the above-described configuration, the first space (SP1) is provided between the bottom surface (22) and the positive electrodes (2) of the secondary battery cells (1) so as to be used as an exhaust space in cases where a gas is discharged from the safety valve, and while enabling the achievement of enhanced safety by holding the positive electrodes (2) at a distance from the bottom surface (22) where water is easily accumulated in cases where the power supply device (100) is flooded or submerged in water.

Description

Technical Field

[0001] The present invention relates to a power supply device.

Background Art

[0002] Power supply devices in which a large number of secondary battery cells are connected in series or in parallel are used as backup power supplies for servers, or as power supply devices for household, commercial, and industrial use in stationary energy storage applications. Furthermore, they are used as power sources for driving vehicles such as hybrid vehicles, electric vehicles, electric carts, and electric scooters, and as power sources for driving assist bicycles and electric tools.

[0003] Such a power supply device attempts to increase the output by connecting a large number of cylindrical secondary battery cells in series. Specifically, as in the power supply device 200 shown in FIG. 7, the cylindrical secondary battery cells 201 are held by a battery holder 210 in a vertical orientation, and the electrodes provided on the end faces of each secondary battery cell 201 are connected by lead plates 204. On the other hand, many of the secondary battery cells 201 have a safety valve provided on the positive electrode side. The safety valve opens when the inside of the secondary battery cell 201 becomes high pressure due to some abnormality, and discharges the internal high-pressure gas to the outside. Therefore, it is necessary to provide a gas duct for discharging gas on the end face (generally the positive electrode side) where the safety valve of the battery cell is provided. As a result, it was necessary to secure space for arranging ducts above and below the power supply device 200.

[0004] On the other hand, as in the power supply device 300 shown in FIG. 8, by holding all the secondary battery cells 301 with the battery holder 310 in a posture where the positive electrode side is on the upper surface, it is possible to secure space for providing a duct only above the secondary battery cells 301, and to reduce the height of the power supply device 300. However, in this configuration, the inventors found through testing that an unintentional short circuit may occur when the power supply device is submerged. Specifically, it was confirmed that in a test of pumping out the salt water after immersing the power supply device in salt water, abnormal heat generation may occur after several hours to several tens of hours due to moisture remaining inside the power supply device.

Prior Art Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2014-102968 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] One of the objectives of the present invention is to provide a power supply device with enhanced safety. Means for solving the problem and effects of the invention.

[0007] To achieve the above objective, a power supply device according to a first embodiment of the present invention comprises a plurality of secondary battery cells each having a positive electrode with a safety valve on one end face, a battery holder that holds a plurality of secondary battery cells, each with a positive electrode on one end face, in an upright, parallel position with the positive electrodes facing vertically downward, and a housing having a floor and a top surface in the internal space housing the battery holder, wherein the battery holder is maintained in a state within the housing such that the positive electrodes of the secondary battery cells are separated from the floor surface to form a first space. With the above configuration, a first space is provided between the positive electrodes of the secondary battery cells and the floor surface, which can be used as an exhaust space when gas is discharged from the safety valve, and further safety can be improved by separating the positive electrodes from the floor surface where moisture tends to accumulate when the power supply device is exposed to submersion or flooding.

[0008] Furthermore, in the power supply device according to the second embodiment of the present invention, in the above configuration, the height of the first space between the floor surface and the positive electrode end face of the secondary battery cell inside the housing is made greater than the distance between the top surface and the other end face of the secondary battery cell. With this configuration, the space for exhausting gas from the safety valve is also used as a space to separate the secondary battery cell from the floor surface, making efficient use of the space inside the housing and enabling a lower profile power supply device.

[0009] Furthermore, a power supply device according to a third embodiment of the present invention further includes, in any of the above configurations, an insulating thermal conductive layer interposed between the top surface and the other end surface of the secondary battery cell, thereby creating a thermal coupling between the top surface and the other end surface of the secondary battery cell. With this configuration, the other end surface of the secondary battery cell located on the top surface side inside the housing is thermally coupled with the thermal conductive layer, making it possible to efficiently dissipate heat from the secondary battery cell.

[0010] Furthermore, in a fourth embodiment of the present invention, the power supply device has, in any of the above configurations, the thermal conductive layer is formed in a sheet shape. This configuration makes it possible to thermally couple the secondary battery cell to the housing via the thermal conductive layer with a simple configuration.

[0011] Furthermore, in a fifth embodiment of the present invention, the power supply device, in any of the above configurations, has a raised portion on the surface of the housing facing the floor surface, and the raised portion defines the first space. With this configuration, it is possible to easily separate the battery holder from the floor surface inside the housing via the raised portion and form a first space for exhausting gas.

[0012] Furthermore, a power supply device according to a sixth embodiment of the present invention further comprises lead plates fixed to the positive and negative electrodes on one end face of the secondary battery cell, in any of the above configurations. This configuration makes it possible to connect the positive and negative electrodes on one end face of the secondary battery cell, contributing to space saving compared to the conventional configuration in which lead plates are arranged on both end faces of the secondary battery cell.

[0013] Furthermore, in a seventh embodiment of the present invention, the power supply device, in any of the above configurations, has the lead plate made of an etched metal plate. With this configuration, it is possible to connect the positive and negative electrodes from the same end face of the secondary battery cell at low cost using an easily customizable etched lead plate.

[0014] Furthermore, in the eighth embodiment of the present invention, the power supply device, in any of the above configurations, has a battery holder in which storage spaces for individually housing the plurality of secondary battery cells are formed by resin partitions. With this configuration, adjacent secondary battery cells can be individually isolated and insulated, thereby improving safety.

[0015] Furthermore, in a ninth embodiment of the present invention, the power supply device, in any of the above configurations, has a battery holder divided into a plurality of sub-holders, which clamp the plurality of secondary battery cells from their respective end faces, and the intermediate portions of the secondary battery cells are exposed from the battery holder. With this configuration, the heat dissipation can be improved by exposing the intermediate portions of the secondary battery cells.

[0016] Furthermore, in any of the above configurations, the power supply device according to the tenth embodiment of the present invention comprises a cylindrical outer casing for the secondary battery cell. [Brief explanation of the drawing]

[0017] [Figure 1] This is a perspective view showing a power supply device according to one embodiment of the present invention. [Figure 2] Figure 1 is a disassembled perspective view of the power supply unit. [Figure 3] Figure 2 is an exploded perspective view of the battery unit. [Figure 4] Figure 3 is an exploded perspective view of the battery unit, seen from a diagonal downward angle. [Figure 5] Figure 1 is a vertical cross-sectional view of the power supply unit along the VV line. [Figure 6] Figure 5 is an enlarged schematic cross-sectional view of the main components of the power supply unit. [Figure 7] This is a schematic cross-sectional view showing a power supply device related to a comparative example. [Figure 8] This is a schematic cross-sectional view showing a power supply device related to another comparative example. [Modes for carrying out the invention]

[0018] Hereinafter, embodiments of the present invention will be described based on the drawings. However, the embodiments shown below are examples for embodying the technical idea of the present invention, and the present invention is not limited to the following. Also, this specification does not in any way identify the members shown in the claims with the members of the embodiments. In particular, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments are not intended to limit the scope of the present invention only to them without specific description, but are merely illustrative examples. Note that the sizes and positional relationships of the members shown in each drawing may be exaggerated for clarity of explanation. Further, in the following description, the same names and reference numerals indicate the same or similar members, and detailed descriptions will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that a plurality of elements are formed of the same member and one member serves as a plurality of elements, or conversely, the function of one member may be realized by sharing it among a plurality of members.

[0019] The power supply device of the present invention is used for various applications such as a backup power supply for servers, a power supply mounted on an electric vehicle such as a hybrid vehicle or an electric vehicle to supply power to a driving motor, a power supply for storing the generated power of natural energy such as solar power generation or wind power generation, or a power supply for storing late-night power. It is particularly suitable for applications that require high power and high current. Hereinafter, as an embodiment of the present invention, a power supply device used as a backup power supply for servers will be described. [Embodiment 1]

[0020] The power supply device 100 according to Embodiment 1 of the present invention is shown in FIGS. 1 to 6. In these figures, FIG. 1 is a perspective view showing the power supply device 100 according to Embodiment 1 of the present invention, FIG. 2 is an exploded perspective view of the power supply device 100 of FIG. 1, FIG. 3 is an exploded perspective view of the battery unit 5 of FIG. 2, FIG. 4 is an exploded perspective view of the battery unit 5 of FIG. 3 as viewed obliquely from below, FIG. 5 is a vertical cross-sectional view of the power supply device 100 taken along the V-V line of FIG. 1, and FIG. 6 is an enlarged schematic cross-sectional view of the main part of the power supply device 100 of FIG. 5, respectively. The power supply device 100 shown in these figures includes a housing 20 and a battery unit 5 housed in the housing 20. (Housing 20)

[0021] As shown in Figures 1 and 2, the housing 20 is a hollow box shape and is made of, for example, a metal case. In the example in Figure 1, it is divided into an upper case 21A and a lower case 21B, and one or more battery units 5 are housed inside. In the example in Figure 2, the upper case 21A has a U-shape in cross-section with the bottom open, and the lower case 21B has a tray shape with the top open, and they are fixed together by screws or the like. The housing 20 also has a top surface 23 and a bottom surface 22 that define the internal space, which are almost flat surfaces. Insulation is also ensured on the inner surfaces of the top surface 23 and the bottom surface 22 by attaching insulating sheets to them as needed. (Battery holder 10)

[0022] As shown in the exploded perspective views of Figures 3 and 4, the battery unit 5 comprises a number of cylindrical secondary battery cells 1, a battery holder 10 that holds them, and a heat conductive layer 30. The battery holder 10 holds the multiple secondary battery cells 1 in an upright position, parallel to each other. This battery holder 10 is divided into two sub-holders, in this case an upper holder 10B and a lower holder 10A, which hold each secondary battery cell 1 from above and below. When held by the battery holder 10, the secondary battery cell 1 has its middle portion exposed from the battery holder 10, as shown in the cross-sectional view of Figure 5, to improve heat dissipation. The upper holder 10B and the lower holder 10A are each made of an insulating material, such as a resin material such as polycarbonate or ABS. In this example, the lower holder 10A forms a storage space 13A that individually houses the multiple secondary battery cells 1 with a partition wall 14. The storage space 13A is formed in a shape that conforms to the shape of the outer casing of the secondary battery cell 1. In this example, the storage space 13A is formed in a cylindrical shape. By individually isolating adjacent secondary battery cells 1 with resin partitions 14 in this way, insulation is enhanced and safety is improved. Furthermore, an opening window 15 is provided on the lower side of the lower holder 10A to expose the positive electrode 2 of the secondary battery cell 1. Each secondary battery cell 1 is connected in series or parallel by lead plates 4 with its positive electrode 2 exposed through the opening window 15.

[0023] The upper holder 10B may be formed in the same way as the lower holder 10A, but it may also have a different shape. In the examples shown in Figures 3 and 4, the upper holder 10B is formed in a plate shape and has a hole formed in it to serve as a storage space 13B into which the end of the secondary battery cell 1 is inserted. By making the storage space 13B thin in this way, a larger area can be secured around the secondary battery cell 1 that is exposed from the battery holder 10, thereby improving heat dissipation performance. (Secondary battery cell 1)

[0024] Each secondary battery cell 1 is a cylindrical secondary battery cell with a cylindrical outer casing. The cylindrical secondary battery cell has electrode surfaces on both end faces. One electrode surface is equipped with a safety valve. The safety valve is a component that opens when the internal pressure of the outer casing rises, releasing the internal gas. While the safety valve is generally provided on the positive electrode 2 side, the present invention does not specify the position of the safety valve on the positive electrode side, but may be placed in other positions, such as the negative electrode side. A cylindrical lithium-ion secondary battery is suitably used for such a secondary battery cell 1. However, the battery pack of the present invention does not limit the secondary battery cells to cylindrical batteries, nor does it limit them to lithium-ion secondary batteries. All rechargeable batteries, such as nickel-metal hydride batteries and nickel-cadmium batteries, can be used as secondary battery cells. (Lead plate 4)

[0025] As shown in Figure 4, a lead plate 4 is fixed to the lower end surface of the secondary battery cell 1. Multiple secondary battery cells 1 are connected in series or parallel via the lead plate 4. The lead plate 4 is made of metal and is welded to the secondary battery cell 1. A lead positioning guide 16 is formed on the outer surface of the battery holder 10, conforming to the outer shape of the lead plate 4, to position the lead plate 4 in a predetermined position. After inserting the secondary battery cell 1 into the storage space 13A of the battery holder 10, the lead plate 4, positioned by the lead positioning guide 16, is fixed to the electrode surface of the secondary battery cell 1 exposed from the battery holder 10 by laser welding, ultrasonic welding, or the like.

[0026] This lead plate 4 connects the positive electrode 2 and the negative electrode of the secondary battery cell 1 on the same end face side, i.e., the lower end face side. Generally, in cylindrical secondary batteries, the positive electrode 2 is positioned at the center of one end face, and the negative electrode is positioned around it. Therefore, by partially bending the lead plate 4 and welding it to protrude towards the positive electrode 2, while welding the periphery of the end face to the other lead plate 4, it becomes possible to connect the positive electrode 2 and the negative electrode on only one side of the secondary battery cell 1. This is advantageous for saving space compared to a configuration where lead plates 204 are welded to both sides of the secondary battery cell 201, as shown in the power supply device 200 in Figure 7, as only one lead plate 4 is needed. Also, since welding is only required on one side, the manufacturing cycle time can be shortened. Such a lead plate 4 is formed, for example, by etching a metal plate. Etched lead plates have the advantage of not requiring a molding die and being able to be made into complex shapes.

[0027] The battery unit 5 may also be equipped with a circuit board. The circuit board is fitted with electronic circuits such as a voltage detection circuit that detects the intermediate potential of a battery assembly in which secondary battery cells 1 are connected in series or parallel, a control circuit that controls charging and discharging, and a safety circuit. The intermediate potential of the multiple secondary battery cells 1 connected in series that constitute the battery assembly is detected from the potential of the lead plate 4 and input to the voltage detection circuit. (Bulk part 17)

[0028] Each secondary battery cell 1 is held by the battery holder 10 such that the positive electrode 2 side, which has a safety valve, faces downward, as shown in the schematic cross-sectional view of Figure 6. Furthermore, a first space SP1 is formed on the lower surface of the battery holder 10, with the lower end surface of the secondary battery cell 1 spaced apart from the floor surface 22 of the housing 20. To form the first space SP1, the battery holder 10 is provided with a riser portion 17 on the surface facing the floor surface 22 of the housing 20, as shown in Figure 4. Multiple riser portions 17 are provided spaced apart along the bottom edge of the battery holder 10. It is preferable that such riser portions 17 are formed integrally with the battery holder 10. However, the riser portion may be provided as a separate component from the battery holder.

[0029] With this configuration, if gas is discharged from the safety valve provided on the positive electrode 2 side of the secondary battery cell 1, it can be used as a gas duct to guide the exhaust gas to the outside of the power supply unit 100. In addition, if the power supply unit 100 is exposed to submersion or flooding, safety can be improved by separating the positive electrode 2 from the floor surface 22 where moisture tends to accumulate. In this way, by providing a gap on the lower end side rather than the upper end side of the secondary battery cell 1, and by holding the secondary battery cell 1 in a position where the positive electrode 2 side faces downward, the gas discharge space can also be used as a space to protect the electrodes from moisture, contributing to the reduction in height of the power supply unit 100. Furthermore, it is preferable that the height of the first space SP1 be greater than the distance D2 between the top surface 23 inside the housing 20 and the upper end surface of the secondary battery cell 1. This further reduces the height of the power supply unit 100. (Thermal conductive layer 30)

[0030] Furthermore, a thermal conductive layer 30 is interposed between the top surface 23 inside the housing 20 and the upper end surface of the secondary battery cell 1. The thermal conductive layer 30 thermally bonds the top surface 23 and the upper end surface of the secondary battery cell 1. This thermal conductive layer 30 is made of a material with excellent thermal conductivity. The thermal conductive layer 30 also has insulating properties, insulating the upper end surface of the secondary battery cell 1, for example, the negative electrode terminal, from the metal housing 20. A silicone resin sheet or the like can be suitably used for such a thermal conductive layer 30. The sheet-like thermal conductive layer 30 can also be attached and fixed to the top surface 23 of the housing 20 with double-sided tape or the like.

[0031] The thickness of the thermal conductive layer 30 is the same as, or slightly thicker than, the distance D2 between it and the upper end surface of the secondary battery cell 1. Preferably, the thermal conductive layer 30 is flexible and is pressed between the upper surface of the secondary battery cell 1 and the top surface 23 of the housing 20 to ensure a tight, gap-free fit. This prevents the formation of an air layer that would hinder heat conduction. The thermal conductive layer 30 may be a separate component, such as a sheet, or it may be formed as a layer created by applying, for example, uncured resin or adhesive between the secondary battery cell 1 and the top surface 23 of the housing 20 and then curing it. This reduces the occurrence of gaps.

[0032] By arranging the heat conduction layer 30 on the upper end surface side of the secondary battery cell 1 in this manner, heat transferred to the upper part of the secondary battery cell 1 by thermal convection can be efficiently dissipated. In particular, in conventional power supply devices 100, it is common to arrange a heat sink or the like on the lower end side of the secondary battery cell 1 as shown in Figure 8. Compared to this configuration, the configuration of this embodiment, which dissipates heat that has moved upward, is advantageous in terms of heat transfer. Furthermore, in a configuration in which a heat sink is placed on the lower side of the secondary battery cell 1, water accumulation on the heat sink can cause unintended short circuits. However, as described above, by arranging the heat dissipation mechanism on the upper end surface side of the secondary battery cell 1 and making the lower end side the first space SP1, the risk of contact with water is reduced, which is also advantageous in terms of safety. [Industrial applicability]

[0033] The power supply device according to the present invention can be suitably used as a backup power supply device that can be mounted on the power supply module of a computer server. It can also be appropriately used as a backup power supply device for wireless base stations such as mobile phones, a power supply for energy storage in homes and factories, a power supply for streetlights, an energy storage device combined with solar cells, a backup power supply for traffic lights, or a power supply for plug-in hybrid electric vehicles, hybrid electric vehicles, electric vehicles, etc., that can switch between EV driving mode and HEV driving mode. [Explanation of Symbols]

[0034] 100, 200, 300…power supply 1, 201, 301… Secondary battery cells 2...Positive electrode 4, 204... Lead plate 5…Battery unit 10, 210, 310... Battery holder 10A... Lower holder 10B... Upper holder 13A, 13B... Storage space 14...Bulkhead 15…Open windows 16…Lead positioning guide 17...Bulk part 20…Cabinet 21A…Upper case 21B...Lower case 22... Floor surface 23... Top surface 30…Thermal conductive layer SP1…first space D2…Distance

Claims

1. Multiple secondary battery cells, each having a positive electrode with a safety valve on one end face, A battery holder that holds multiple secondary battery cells, each with a positive electrode on one end face, in an upright, parallel position with the positive electrodes facing vertically downwards, The internal space for housing the battery holder includes a housing having a floor surface and a top surface, A power supply device comprising, The battery holder is maintained inside the housing in a state in which the positive electrode of the secondary battery cell is separated from the floor surface to form a first space. The battery holder has a raised portion located along the edge of the bottom surface facing the floor surface of the housing, A power supply device comprising a first space defined between the raised portions provided on opposing edges.

2. A power supply device according to claim 1, A power supply device wherein, inside the housing, the height of the first space between the floor and the positive electrode end face of the secondary battery cell is greater than the distance between the top surface and the other end face of the secondary battery cell.

3. The power supply device according to claim 2, further, A power supply device comprising an insulating thermal conductive layer interposed between the top surface and the other end surface of the secondary battery cell, which thermally couples the top surface and the other end surface of the secondary battery cell.

4. A power supply device according to claim 3, The aforementioned heat conductive layer is formed in the shape of a sheet in the power supply device.

5. A power supply device according to any one of claims 1 to 4, further, A power supply device comprising lead plates fixed to the positive and negative electrodes on one end face of the aforementioned secondary battery cell.

6. A power supply device according to claim 5, The lead plate is made of an etched metal plate in this power supply device.

7. A power supply device according to any one of claims 1 to 6, The power supply device wherein the battery holder has storage spaces for individually housing the plurality of secondary battery cells, formed by resin partitions.

8. A power supply device according to any one of claims 1 to 7, A power supply device in which the battery holder is divided into a plurality of sub-holders, each holding the plurality of secondary battery cells from their respective end faces, and the intermediate portions of the secondary battery cells are exposed from the battery holder.

9. A power supply device according to any one of claims 1 to 8, The aforementioned secondary battery cell is a power supply device comprising a cylindrical outer casing.

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