Patent Application
20230318120
The present disclosure relates to a battery pack and a device configured to exhaust gas from the battery pack.
Non-aqueous electrolyte secondary batteries such as lithium-ion batteries may often be used in the form of battery pack, in which a plurality of batteries are electrically connected to each other and enclosed in a case. When an abnormal condition occurs in a battery within the battery pack, it is possible that the battery may generate a large amount of high-temperature flammable gas. If the generated gas is not expelled out of the battery pack appropriately, there may be a risk that the internal pressure of the battery pack increases, resulting in rupture of the battery pack case. Generally, it is required that the battery pack case have a hermetically sealed structure in order to prevent water or dust from entering the inside of the battery pack. However, in cases where an abnormal condition occurs in a battery and consequently the internal pressure of the case increases, it is necessary to expel the gas to outside urgently.
In many cases, abnormal conditions of a battery tend to occur during charge, during which the battery is connected to a charger. For example, PTL 1 discloses a charger that causes a vent hole of a battery pack to open when charging the battery pack.
PTL 1: Japanese Utility Model Unexamined Publication No. H06-064360
In the charger disclosed in PTL 1, however, it is foreseen that the gas exhausted from the battery pack remains in a gap space between the battery pack and the charger, so that the gas from the battery pack will not be exhausted smoothly. Moreover, electrode contacts for charging are present in the gap space between the battery pack and the charger. There is a possibility that when the gas is exhausted violently, contact failure occurs between the contacts. Because the generated gas is flammable, there is a risk of catching fire and causing fire in some cases.
It is an object of the present disclosure to provide a means to smoothly and safely exhaust gas from a battery pack when an abnormal condition occurs in a battery and the internal pressure of a battery pack increases.
According to the present disclosure, a battery pack includes a plurality of batteries, and a case enclosing the plurality of batteries. The case includes: an exhaust hole penetrating the case; a partition wall being in a closed-bottomed tubular shape, the partition wall surrounding the exhaust hole within the case; a sealing member disposed within a tube defined by the partition wall, the sealing member closing the exhaust hole; and a biasing member disposed within the tube defined by the partition wall and biasing the sealing member in a direction toward the exhaust hole. The partition wall includes a vent hole forming a gas exhaust path together with the exhaust hole. The sealing member is configured to move inward when pressed from outside of the case to open the exhaust hole.
According to the present disclosure, a device configured to exhaust gas is adapted for use with a battery pack including a plurality of batteries and a case enclosing the plurality of batteries and including an exhaust hole and a sealing member closing the exhaust hole. The device includes: a pedestal on which the battery pack is to be placed; a gas inlet hole formed in the pedestal at a location overlapping the exhaust hole of the battery pack; a exhaust duct being a vent path formed in the pedestal and communicating with the gas inlet hole, for guiding the gas exhausted from the battery pack to outside of the device; and a pressing part protruding from the gas inlet hole, the pressing part configured to press the sealing member of the battery pack.
The battery pack and the device provided with a gas exhausting function according to the present disclosure make it possible to exhaust gas smoothly and safely from the battery pack when an abnormal condition occurs in a battery therein and the internal pressure of the battery pack increases.
Hereafter, exemplary embodiments of the present disclosure will be described in detail with reference to the drawings. Specific shapes, materials, directions, numerical values, and the like mentioned in the following description are merely illustrative examples for the purposes of facilitating understanding of the present disclosure, and they may be changed or modified to meet the applications of use, purposes, specifications, and the like.
A plurality of batteries 50 are electrically connected to each other to construct a battery module. The battery module has a structure in which, for example, a plurality of battery groups each including a plurality of batteries 50 connected in parallel are connected in series, so as to output a voltage that is suitable for the appliance that uses the battery module. Each of batteries 50 is, for example, a cylindrical battery. Although
Battery 50 is a cylindrical battery including a closed-bottomed cylindrical tubular outer covering can, and a sealing element that closes an opening of the outer covering can. An insulative gasket is provided between the outer covering can and the sealing element. In a cylindrical battery, generally, the sealing element serves as the positive electrode terminal, and the outer covering can serves as the negative electrode terminal. The sealing element is provided with a vent valve for exhausting gas when an abnormal condition occurs in battery 50 and the internal pressure rises. Note that the vent valve may be provided at the bottom of the outer covering can.
The plurality of batteries 50 are accommodated in holder 51 within case 90. Holder 51 fixes the arrangement of batteries 50 and maintains the form of the battery module. In addition, battery pack 10 includes, for example, terminal plates that electrically connect the plurality of batteries 50. The terminal plates include a positive electrode terminal plate electrically connected to the sealing element, which is the positive electrode terminal of each of batteries 50, and a negative electrode terminal plate electrically connected to the outer covering can, which is the negative electrode terminal of each of batteries 50. The terminal plates may be integrated with holder 51.
Case 90 is provided with an external terminal (not shown) electrically connected to each of batteries 50. The external terminal is provided, for example, on case bottom 40 and is used as a terminal for supplying a direct-current voltage when battery pack 10 is built into an appliance that is used with battery pack 10. The external terminal is also used in charging battery pack 10 (batteries 50).
With reference to
As illustrated in
Case bottom 40 is formed with exhaust hole 41, which penetrates case bottom 40. Exhaust hole 41 is, for example, a circular-shaped hole. Partition wall 44 having a closed-bottomed cylindrical tubular shape is formed inside case bottom 40 so as to surround exhaust hole 41 in a direction toward case main body 20. Partition wall 44 accommodates spring (biasing member) 42 and sealing member 43. Spring 42 presses sealing member 43 toward exhaust hole 41. Sealing member 43 has the same shape as exhaust hole 41 when viewed in plan and is slightly larger than exhaust hole 41. Sealing member 43 closes exhaust hole 41. In partition wall 44, vent hole 45 is formed at a location higher than sealing member 43 and upward from exhaust hole 41 of partition wall 44, in a state where sealing member 43 is pressed onto exhaust hole 41.
In case bottom 40, spring 42 biases sealing member 43 so as to close exhaust hole 41 in a normal condition, to prevent gas from being exhausted from case bottom 40.
It is possible to push press member 43 into exhaust hole 41 from outside, against the elastic force of spring 42. Sealing member 43 is pressed beyond the position of vent hole 45, whereby exhaust hole 41 is opened to form a gas exhaust path together with vent hole 45.
Thus, battery pack 10 maintains a hermetically sealed condition in a normal condition, and battery pack 10 is configured to form a gas exhaust means by imparting pressure externally.
The sizes of exhaust hole 41 and vent hole 45 are determined so that the gas exhaust condition will be appropriate. The gas exhaust speed is determined by the pressure in case 90 and the aperture areas of exhaust hole 41 and vent hole 45. Because the gas to be exhausted contains a flammable component, it is necessary to prevent the gas from being ignited when the gas is exhausted from case 90. As a result of research conducted by the present inventors, it has been found that the gas exhaust speed is an important factor in preventing ignition and that the effect of preventing ignition will be high when the gas exhaust speed exceeds a predetermined threshold value. For this reason, it is desirable that the aperture areas of exhaust hole 41 and vent hole 45 be determined so that the gas exhaust speed exceeds the threshold value.
In battery pack 10 according to the present exemplary embodiment, exhaust hole 41 is an opening that receives a pressing part from outside, as will be described later. Therefore, it is possible to suitably adjust the aperture area of vent hole 45. It is possible to set an exhaust speed by setting the exhaust area of vent hole 45 appropriately.
Vent hole 45 may be formed such that a part of partition wall 44 is a mesh structure. The term “mesh structure” means a lattice-shaped or mesh-shaped structure that includes periodically aligned fine line-shaped partitions. Note that each of the gaps between the fine line-shaped partitions serves as an opening for exhaust gas. For example, the width of each of the partitions is set to be smaller than the width of the opening, and the aperture ratio (the total area of the openings) is set to be greater than 50%. In addition, it is preferable that the mesh structure be composed of a metal.
By forming vent hole 45 with a mesh structure, sparks can be trapped easily while smooth gas exhaust performance is provided. When sparks are efficiently trapped by the mesh structure, the effect of preventing ignition is even higher.
Next, with reference to
Pedestal 61 serves as a stand for placing battery pack 10 thereon during charge. Pedestal 61 is provided with gas inlet hole 62. Exhaust duct 64 is provided under pedestal 61. Exhaust duct 64 communicates with gas inlet hole 62, passes through the inside of charger 60, and has an opening to outside.
It is desirable that pedestal 61 be formed in a shape that corresponds to the bottom surface of case bottom 40 of battery pack 10. When pedestal 61 is formed in this way, it is possible to exhaust gas through gas inlet hole 62 without forming a gap between case bottom 40 and pedestal 61 when battery pack 10 is placed thereon.
When battery pack 10 is placed, gas inlet hole 62 overlaps exhaust hole 41 of battery pack 10 and introduces the gas exhaust hole 41 from the gas exhaust path of battery pack 10 to guide the gas to exhaust duct 64.
Exhaust duct 64 exhaust the gas introduced from gas inlet hole 62 to the outside of charger 60. In the present exemplary embodiment, opening 66 is provided in a side surface of charger 60. Opening 66 may be provided in either one or both of opposite side surfaces of charger 60.
Pressing part 63 for pressing sealing member 43 of battery pack 10 upward protrudes above the surface of pedestal 61 through gas inlet hole 62 toward battery pack 10. In the present exemplary embodiment, pressing part 63 extends outward from exhaust duct 64 through gas inlet hole 62 and penetrates the surface of pedestal 61. However, the configuration of pressing part 63 is not limited thereto, and gas inlet hole 62 may be provided with pressing part 63 protruding toward battery pack 10.
With the above-described configuration, charger 60 is able to open the gas exhaust path that battery pack 10 has, when battery pack 10 is placed on charger 60, and to exhaust the gas to the outside of charger 60 through the path indicated by the arrows shown in
Exhaust duct 64 may be provided with fire-extinguishing agent 65. Fire-extinguishing agent 65 is preferably disposed close to opening 66. As a result, it is possible to extinguish fire quickly even when the gas catches fire, and it is possible to prevent fire from propagating to the inside of battery pack 10. Possible examples of fire-extinguishing agent 65 include fire-extinguishing agents composed of hydrogen carbonates or phosphate salts.
Exhaust duct 64 may be provided with a mesh-shaped extinguishing structure in opening 66. It is desirable that the mesh structure is composed of a metal. By providing the mesh-shaped extinguishing structure in exhaust duct 64, sparks can be trapped easily while smooth gas exhaust performance is provided. When sparks are efficiently trapped by the mesh structure, the effect of preventing ignition is even higher. Although
With reference to
Normally, the gas exhaust mechanism of battery pack 10 is not actuated when installed in electrical appliance 80. Accordingly, sealing member 43 closes exhaust hole 41, as illustrated in
There may be cases in which an abnormal condition occurs inside battery pack 10 due to a fault of electrical appliance 80 or influences from ambient temperature, resulting in an increase of the internal pressure of battery pack 10. In this case, it is preferable that sealing member 43, which is the gas exhaust mechanism provided in battery pack 10, is pressed upward to be able to exhaust mechanism the gas generated in battery pack 10 outside.
In this case, it is preferable that the pressing part for pressing sealing member 43 upward be configured to be movable such that it is normally accommodated inside electrical appliance 80 but emerges when an abnormal condition of battery pack 10 is detected. The specific structure of this configuration is not particularly limited.
As for abnormal conditions in battery pack 10, it is possible that, for example, the temperature of battery pack 10 is measured with electrical appliance 80, and when the temperature exceeds a predetermined range, it is determined to be an abnormal condition. The temperature of battery pack 10 can be estimated by measuring the temperature of the external surface of the case or other locations. It is also possible to detect an abnormal condition of battery pack 10 by detecting an output voltage or the like of battery pack 10.
Although exemplary embodiment of the present disclosure have been described hereinabove, they are merely illustrative examples and not intended to exclude embodiments other than those described above. For example, although the external appearance of the battery pack is in a rectangular parallelepiped shape, the external appearance is not limited thereto and may be in a circular cylindrical shape. Other shapes are also possible. In addition, although all the side surfaces of the rectangular parallelepiped shape are substantially the same shape, the sizes and shapes of the adjacent surfaces may be different. The proportions of the case lid and the case main body are not limited to those disclosed in the drawings. Furthermore, in the form in which the battery pack is actually used, there may be cases in which protrusions, recesses, handles, terminals, and the like are provided around the battery pack, but these alterations are made within the scope in which they do not affect the operations of the exhaust mechanism described in the present disclosure, and they do not affect the workings of the exhaust mechanism of the present exemplary embodiments.
The battery pack according to the present disclosure is usable as a component for supplying electric power to electronic devices. Examples include battery packs for lap-top computers, battery packs for cleaners, and battery packs for power tools. The battery pack is also applicable to batteries for power assisted bicycles. Applications of use other than those listed herein are also possible as long as they are within the applications of use of battery pack.
The present disclosure is not limited to the foregoing exemplary embodiments and modified examples, but various other modifications and alterations are of course possible within the scope of the claims set forth herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-160760 | Sep 2020 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/028695 | 8/3/2021 | WO |
