Battery pack and substrate module

Abstract

In this battery pack (1) according to one embodiment, a plurality of batteries (5) are connected to each other, and a substrate module (10) is incorporated. The substrate module (10) is configured with a substrate (11), and a battery protection element (12) and a temperature detection element (13) mounted on a front surface (11a) of the substrate, and a rear surface (11b) of the substrate module opposes the batteries (5). The temperature detection element (13) is mounted at the edge of the front surface (11a) of the substrate (11) in the vicinity of a notch (11c). With such a structure, the temperature detection element (13) can detect not only the temperature of the space above the substrate (11), but also the temperature of the batteries (5). (Selected drawing: fig. 1)

Description

Battery Pack and Substrate Module

[0001] The present invention relates to a battery pack in which a plurality of secondary batteries are connected, and a substrate module incorporated in such a battery pack.

[0002] Generally, components and structures for ensuring the safety of the battery are provided in the battery pack. For example, in Patent Document 1, two batteries arranged side by side so that the polarities of the + electrode and the - electrode are opposite are connected in series by welding a conductive plate to the electrode portion on one end face side, and a substrate unit is arranged facing the electrode portion on the other end face side, and a fuse is mounted on the surface facing the battery, and a battery pack in which these batteries and the substrate unit are housed in a case formed of a resin material is disclosed.

[0003] Japanese Patent Application Laid-Open No. 2022-18174

[0004] According to the above prior art, when a current exceeding the assumption flows, the fuse is blown by the heat generated thereby and the circuit is interrupted, so it is considered that the continuous flow of overcurrent can be prevented. However, with the above structure, it is impossible to detect a change in the external temperature (ambient temperature) of the battery, and it is difficult to respond to a high temperature state caused by external factors.

[0005] Therefore, an object of the present invention is to provide a technique for improving the safety of a battery.

[0006] The battery pack of the present disclosure includes a plurality of secondary batteries, a battery protection element that is electrically connected to the secondary batteries and restricts the flow of current under predetermined conditions provided on one surface of the substrate, and a temperature detection element provided at the edge of one surface of the substrate, and a substrate module in which the other surface of the substrate faces the secondary batteries. Further, the substrate module of the present disclosure is a substrate module incorporated in a battery pack in which a plurality of secondary batteries are connected, and includes a battery protection element that restricts the flow of current under predetermined conditions, a temperature detection element that detects temperature, the battery protection element is provided on one surface, the temperature detection element is provided at the edge of one surface, and the other surface faces the secondary batteries, and a substrate that is electrically connected to the secondary batteries.

[0007] Preferably, in the battery pack according to the above-described embodiment, the substrate module has a notch in which a part of its outer periphery is cut inward, and the temperature sensing element is provided near the notch.

[0008] More preferably, in any of the above-described embodiments of the battery pack, the secondary battery is a cylindrical battery, and the substrate module has a dimension in the short direction of the substrate that is smaller than the diameter of the cylindrical battery, and the other surface of the substrate faces the terminal portion of the cylindrical battery.

[0009] Furthermore, in any of the above-described embodiments of the battery pack, the circuit board module either has the battery protection element and the temperature detection element as separate components, or the battery protection element and the temperature detection element are combined into a single component.

[0010] According to the battery pack and circuit board module of this disclosure, the current flow is restricted depending on the situation by the battery protection element, and both the external temperature and the battery temperature are detected by the temperature detection element. This allows for appropriate action to be taken according to the detected temperature, thereby improving the safety of the battery pack. Furthermore, since the battery protection element and temperature detection element are concentrated on one side of the circuit board, fewer wires are required compared to when they are distributed on both sides, thus reducing manufacturing costs. In addition, the circuit board module is easy to install and remove, improving work efficiency.

[0011] This is a perspective view showing the main parts of the battery pack 1 of the first embodiment. This is a diagram showing the assembly process of the battery pack 1 using the circuit board module 10. This is a perspective view showing the main parts of the battery pack 2 of the second embodiment. This is a diagram showing the assembly process of the battery pack 2 using the circuit board module 20.

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings, using as an example a battery pack in which a plurality of cylindrical secondary batteries (hereinafter abbreviated as "batteries") are connected in series. For the sake of convenience of explanation, directions related to the configuration of the embodiment may be indicated as up, down, left, and right, in accordance with the direction on the page in which the drawings are placed.

[0013] [First Embodiment] Figure 1 is a perspective view showing the main parts of the battery pack 1 of the first embodiment. The battery pack 1 mainly comprises two batteries 5 and a circuit board module 10. Three lead wires 15 to 17, red, white, and black, are connected to the circuit board module 10. For visibility, the red lead wire 15 is lightly shaded in the drawing, and the black lead wire 17 is darkly shaded.

[0014] The two batteries 5 are arranged so that their outer surfaces are in contact with each other, with their terminals facing opposite directions. The circuit board module 10 consists of a circuit board 11 with a cutout in part of its outer edge, and a fuse 12 and a thermistor 13 mounted on one side (hereinafter referred to as the "front surface") 11a of the circuit board 11, which are connected to the upper terminals of the two batteries 5 via a lead plate 14, with the other side (hereinafter referred to as the "back surface") of the circuit board 11 facing the two batteries 5. Although not visible in Figure 1, the lower terminals of the two batteries 5 are also connected to each other via a lead plate.

[0015] Figure 2 shows the assembly process for the battery pack 1 using the circuit board module 10. The structure of the circuit board module 10 will be further explained below in accordance with the work flow.

[0016] Figure 2(A) is a plan view showing the circuit board module 10 as a single unit. The circuit board 11 has a notch 11c on one side in the middle of its longitudinal direction, where a portion of the outer periphery is cut out inward in a roughly U-shape. The maximum dimension of the circuit board 11 in the short direction is smaller than the diameter of the battery 5. Note that the wiring of the conductors on the circuit board 11 is not shown in the figure.

[0017] The thermistor 13 is mounted on the edge of the surface 11a of the substrate 11, near the notch 11c. Specifically, the thermistor 13 is an NTC thermistor, and it feeds back the detected temperature to the connected device. This allows the device to perform appropriate control according to the temperature. The fuse 12 is mounted in the middle of the longitudinal direction of the surface 11a, slightly away from the thermistor 13. The fuse 12 is, for example, a current fuse, and has the characteristic of melting due to the heat generated when an excessive current flows, thereby interrupting the flow of current. In other words, it can be described as a battery protection element that limits the flow of current under predetermined conditions.

[0018] Prior to attaching the circuit board module 10 to the battery 5, as shown in Figure 2(B), two lead plates 14-1 and 14-2 and three lead wires 15-17 are soldered to the surface 11a of the circuit board. The two batteries 5 are then bonded together at a portion of their outer surfaces. Then, as shown in the upper diagram of Figure 2(C), with the back surface 11b of the circuit board facing upwards, lead plate 14-1 is welded to the negative terminal 5-1n of the left battery 5-1, and lead plate 14-2 is welded to the positive terminal 5-2p of the right battery 5-2. Furthermore, as shown in the lower diagram of Figure 2(C), lead plate 18 is welded to the terminals on the opposite sides, namely the positive terminal 5-1p of the left battery 5-1 and the negative terminal 5-2n of the right battery 5-2.

[0019] As a result, the red lead wire 15 is electrically connected to the positive terminal 5-2p of the right battery, and the black lead wire 17 is electrically connected to the negative terminal 5-1n of the left battery. In addition, the white lead wire 16 is connected to the thermistor 13 provided on the wiring path between the black lead wire 17 and the negative terminal 5-1n of the left battery.

[0020] Subsequently, the base portions of the lead plates 14-1 and 14-2 are bent so that, as shown in Figure 2 (D), the surface 11a of the substrate faces upward and the back surface 11b faces the two batteries 5-1 and 5-2 (the same state as shown in Figure 1). Then, insulating plates are attached to cover the entire upper and lower sides of the batteries in this state, and the entire assembly, excluding the three lead wires, is packed with heat-shrink tubing to complete the battery pack 1 shown in Figure 2 (E).

[0021] In other words, in the completed battery pack 1, the thermistor 13 is located approximately directly above the point where the negative terminal 5-1n of the left battery and the positive terminal 5-2p of the right battery are adjacent, as shown in the upper diagram of Figure 2 (D). Also, a recessed space 5s is formed along the outer surfaces of the two batteries 5-1 and 5-2 near the contact point of their outer surfaces. The dashed line VS in the figure represents a virtual surface in contact with the outer surfaces of the two batteries 5-1 and 5-2. In the completed battery pack 1, the outer casing tube is located slightly outside of this virtual surface VS.

[0022] If the substrate were not formed with a notch, the substrate would be interposed between the recessed space and the space above the substrate, separating these spaces. In contrast, in this embodiment, since the substrate 11 has a notch 11c, there is nothing obstructing the space between the recessed space 5s and the space above the substrate 11, and these spaces communicate freely with each other. Therefore, the thermistor 13, which is located on the surface 11a of the substrate 11 near the notch 11c, can not only detect the temperature of the space above the substrate 11 (external temperature), but can also detect the temperature of the battery transmitted from the recessed space 5s more reliably than when the substrate is not formed with a notch.

[0023] Next, the battery pack 2 of the second embodiment and the circuit board module 20 incorporated therein will be described. The second embodiment is a variation of the first embodiment. Parts of the configuration of the second embodiment that are common to the first embodiment will not be explained.

[0024] [Second Embodiment] Figure 3 is a perspective view showing the main parts of the battery pack 2 of the second embodiment. The battery pack 2 mainly comprises three batteries 5 and a circuit board module 20. The three batteries 5 are connected via lead plates 28, with the lower terminals of the left and central batteries 5-1 and 5-2 connecting to each other, and the upper terminals of the central and right batteries 5-2 and 5-3 connecting to each other. Note that the lead plates 28 connecting the upper terminals are covered by an insulating plate 29 and are not visible.

[0025] The circuit board module 20 consists of a circuit board 21 and a PTC element 22 and a thermistor 23 mounted on the surface 21a of the circuit board 21, to which white and black lead wires 26 and 27 are connected. The back surface of the circuit board module 20 faces the battery 5 and is connected to the negative terminal of the entire series-connected battery (specifically, the negative terminal of the left battery 5-1) via a lead plate 24. In addition, a red lead wire 25 is connected to the positive terminal of the entire battery (specifically, the positive terminal of the right battery 5-3).

[0026] Figure 4 shows the assembly process for the battery pack 2 using the circuit board module 20. The structure of the circuit board module 20 will be further explained below in accordance with the work flow.

[0027] Figure 4(A) is a plan view showing the circuit board module 20 on its own. The circuit board 21 has a roughly D-shape with a large width in plan view. The dimension of the circuit board 21 in the shorter direction (in other words, the height in the D-shape) is smaller than the diameter of the battery 5.

[0028] The PTC element 22 is mounted approximately in the center of the surface 21a of the substrate 21. The PTC element 22 has the characteristic of increasing its electrical resistance and restricting the current flow when an excessive current flows and reaches a predetermined temperature, and can be described as a battery protection element that limits the flow of current under predetermined conditions. The thermistor 23 is mounted near the corner of the D-shaped edge of the surface 21a.

[0029] Prior to attaching the circuit board module 20 to the battery 5, as shown in Figure 4(B), the lead plate 24 and the two lead wires 26 and 27 are soldered to the surface 21a of the circuit board. Then, as shown in the upper diagram of Figure 4(C), with the back surface 21b of the circuit board facing upwards, the lead plate 24 is welded to the negative terminal 5-1n of the left battery, and the lead plate 28 is welded to the positive terminal 5-2p of the central battery and the negative terminal 5-3n of the right battery. Furthermore, as shown in the lower diagram of Figure 4(C), for the terminals on the opposite side, the lead plate 28 is welded to the positive terminal 5-1p of the left battery and the negative terminal 5-2n of the central battery, and the lead plate 30 is welded to the positive terminal 5-3p of the right battery.

[0030] Next, as shown in Figure 4 (D), an insulating plate 29 is attached so as to cover the entire terminals of the two batteries 5-2 and 5-3 in the center and on the right, which are connected by a lead plate 28. Then, the base portion of the lead plate 24 is bent, and the lead wires 25 are welded to the lead plate 30, so that the surface 21a of the substrate faces upward and the back surface 21b faces part of the battery 5-1 on the left and the battery 5-2 in the center (the same state as shown in Figure 3).

[0031] Then, insulating plates are attached to the entire upper and lower parts of the battery in this state, and the entire assembly, excluding the three lead wires, is packed with heat-shrink tubing to complete the battery pack 2 shown in Figure 4 (E).

[0032] Thus, the substrate 21 forming the substrate module 20 of the second embodiment does not have a notch like the first embodiment described above. However, as shown in Figure 4 (D), when attached to the battery 5, it is positioned inside the virtual plane VS, so a gap is formed between the outer tube, which is located slightly outside the virtual plane VS, and the substrate 21. Through this gap, the recessed space 5s that occurs near the adjacent part of the battery 5 can communicate with the space above the substrate 21. The thermistor 23 is provided at a position near the D-shaped corner on the edge of the substrate 21, and when the substrate module 20 is attached to the battery 5, it is located directly above the recessed space 5s. Therefore, the thermistor 23 can detect not only the temperature of the space above the substrate 11 (external temperature) but also the temperature of the battery transmitted from the recessed space 5s.

[0033] As described above, in the battery packs 1 and 2 of the first and second embodiments, the battery protection elements (fuse 12, PTC element 22) provided on the circuit board modules 10 and 20 can limit the flow of current according to the situation, and the temperature detection elements (thermistors 13 and 23) can detect both the rise in battery temperature and the rise in external temperature. Therefore, with battery packs 1 and 2, it is possible to take prompt and appropriate action not only against heat generation from the battery itself but also against dangerous high-temperature conditions caused by external factors such as fire or temperature rise inside the vehicle, thereby further improving the safety of the battery pack.

[0034] Furthermore, in the circuit board modules 10 and 20, the temperature sensing element and the battery protection element are concentrated on one side of the circuit boards 11 and 21. Compared to cases where these elements are distributed and mounted on both sides, less wiring is required, thus reducing manufacturing costs. In addition, because the circuit board modules 10 and 20 have a simple structure, they are easy to install and remove, making it easy to replace components and dispose of them.

[0035] The present invention is not limited to the embodiments described above and can be implemented in various modified forms. In the embodiments described above, the substrate module 10 is incorporated into a battery pack 1 in which two batteries 5 are connected in series, and the substrate module 20 is incorporated into a battery pack 2 in which three batteries 5 are connected in series. However, substrate modules having a similar structure may be incorporated into battery packs with a different number of batteries. However, the substrate module must be incorporated into the negative terminal side of the battery pack, and the shape of the substrate, the wiring of conductors to the substrate, and the mounting position of each element can be changed depending on the number of batteries and their arrangement. Furthermore, it is also possible to incorporate substrate modules having a similar structure into a battery pack in which multiple batteries are connected in parallel.

[0036] In the embodiments described above, a fuse 12 is provided as a battery protection element in the substrate module 10 of the first embodiment, and a PTC element 22 is provided in the substrate module 20 of the second embodiment. However, the fuse 12 in the substrate module 10 may be replaced with a PTC element, or the PTC element 22 in the substrate module 20 may be replaced with a fuse. Furthermore, although the substrate 21 forming the substrate module 20 does not have a notch, a notch like that in the substrate 11 forming the substrate module 10 may be formed in the substrate 21. In that case, the position of the conductor wiring on the substrate 21 can be changed as needed.

[0037] In the embodiment described above, the battery protection element (fuse 12, PTC element 22) and the temperature detection element (thermistors 13, 23) are provided separately on the same surface of the substrate. However, instead of these, a component that combines the roles of both the battery protection element and the temperature detection element (for example, a thermal fuse) may be provided.

[0038] Although the battery packs 1 and 2 in the above-described embodiment are composed of multiple cylindrical secondary batteries, they may be composed of secondary batteries of other shapes (for example, rectangular or flat), and accordingly, if necessary, the shape of the substrate, the wiring of conductors to the substrate, and the mounting position of each element can be changed.

[0039] 1 Battery pack 5 Battery 10 Circuit board module 11 Circuit board 11a Front 11b Back 11c Notch 12 Fuse (Battery protection element) 13 Thermistor (Temperature sensing element) 14 Lead plate 15 Red lead wire 16 White lead wire 17 Black lead wire 18 Lead plate

Claims

1. A battery pack comprising a plurality of secondary batteries and a substrate module electrically connected to the secondary batteries, wherein a battery protection element is provided on one side of the substrate to limit the flow of current under predetermined conditions, a temperature detection element is provided on the edge of the one side, and the other side of the substrate faces the secondary batteries.

2. A battery pack according to claim 1, wherein the substrate module has a notch in which a part of its outer periphery is cut inward, and the temperature sensing element is provided near the notch.

3. A battery pack according to claim 1 or 2, wherein the secondary battery is a cylindrical battery, and the substrate module is characterized in that the dimension of the substrate in the short direction is smaller than the diameter of the cylindrical battery, and the other surface of the substrate faces the terminal portion of the cylindrical battery.

4. The battery pack according to claim 1, characterized in that the circuit board module has the battery protection element and the temperature detection element as separate components, or the battery protection element and the temperature detection element as a single component.

5. A circuit board module incorporated into a battery pack comprising multiple rechargeable batteries connected together, the circuit board comprising: a battery protection element that limits the flow of current under predetermined conditions; a temperature detection element that detects temperature; and a circuit board electrically connected to the rechargeable batteries, wherein the battery protection element is provided on one side, the temperature detection element is provided on the edge of the one side, and the other side faces the rechargeable batteries.

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