Energy storage device and water ingress detection method

Abstract

This invention provides a power storage device and a water ingress detection method that can detect water ingress before water comes into contact with the battery pack. [Solution] The energy storage device comprises a battery pack, a lower case having a groove formed on the outside of the mounting surface on which the battery pack is directly or indirectly placed, recessed below the lower end of the battery pack, a first detection wire with a first exposed conductive portion installed inside the groove, a second detection wire with a second exposed conductive portion installed inside the groove at a predetermined distance from the first exposed conductive portion, and an electronic device to which the first detection wire and the second detection wire are connected and to measure the resistance or potential difference between the first detection wire and the second detection wire. The water ingress detection method measures the resistance or potential difference between the first detection wire and the second detection wire, and estimates that water ingress has occurred if the measured resistance or potential difference is less than or equal to a predetermined value.

Description

Technical Field

[0001] The present disclosure relates to a power storage device and a water ingress detection method.

Background Art

[0002] Patent Document 1 discloses a battery pack in which a conduction detection electrode for water ingress detection is disposed on the upper surface of a secondary battery via an insulating sheet, and a conductive sheet for secondary battery expansion detection is disposed at a distance above the conduction detection electrode for water ingress detection.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the battery pack described in Patent Document 1, since the conduction detection electrode for water ingress detection is disposed on the upper surface of the secondary battery, there is a possibility that the secondary battery is in a considerably waterlogged state when the conduction detection electrode detects water ingress.

[0005] In view of the above problems, the present disclosure relates to providing a power storage device and a water ingress detection method capable of detecting water ingress before water splashes on the battery pack.

Means for Solving the Problems

[0006] The energy storage device according to claim 1 comprises a battery pack, a lower case having a mounting surface on which the battery pack is directly or indirectly mounted, and having a groove formed on the outside of the mounting surface that is recessed below the lower end of the battery pack, a first detection wire having a first exposed conductive portion with an exposed conductive portion, wherein the first exposed conductive portion is installed inside the groove, a second detection wire having a second exposed conductive portion with an exposed conductive portion, wherein the second exposed conductive portion is installed inside the groove at a predetermined distance from the first exposed conductive portion, and an electronic device to which the first detection wire and the second detection wire are connected, the electronic device for measuring the resistance or potential difference between the first detection wire and the second detection wire.

[0007] In the energy storage device according to claim 1, since the first exposed conductive portion and the second exposed conductive portion are installed inside a groove that is recessed below the lower end of the battery pack, water ingress can be detected when water that has entered accumulates inside the groove, and water ingress can be detected before water comes into contact with the battery pack.

[0008] The energy storage device according to claim 2 comprises, in claim 1, an upper case which cooperates with the lower case to house the battery pack inside, the lower case having a first flange portion, the upper case having a second flange portion which fits with the first flange portion, and the groove portion which is formed in the first flange portion.

[0009] In the energy storage device according to claim 2, if water enters between the first flange portion and the second flange portion, water ingress can be detected before the water comes into contact with the battery pack.

[0010] The energy storage device according to claim 3 is as described in claim 1 or claim 2, wherein the groove is formed around the entire circumference outside the mounting surface described above, the first detection line and the second detection line are each arranged around the entire circumference of the groove, and a plurality of the first exposed conductive portion and the second exposed conductive portion are each provided.

[0011] The energy storage device according to claim 3 makes it possible to detect water ingress at multiple locations around the mounting surface, thereby suppressing the possibility of missing water ingress detection.

[0012] The energy storage device according to claim 4 is characterized in that, in any one of claims 1 to 3, both the first exposed conductive portion and the second exposed conductive portion are located in the lower part of the interior of the groove. Here, the lower part of the interior of the groove is typically below the midpoint of the groove's depth.

[0013] In the energy storage device according to claim 4, the time from the detection of water intrusion into the lower case to the water reaching the mounting surface can be delayed compared to the case where at least one of the first exposed conductive portion and the second exposed conductive portion is located in the upper part of the inside of the groove.

[0014] The water ingress detection method according to claim 5 measures the resistance or potential difference between a first detection wire, which has a first exposed conductive portion with an exposed conductive portion, and a second detection wire, which has a second exposed conductive portion with an exposed conductive portion, which is positioned at a predetermined distance from the first exposed conductive portion, both located inside a groove formed on the outside of the mounting surface on which the battery pack is directly or indirectly placed in the lower case, and presuming that water has entered the groove if the measured resistance or potential difference is less than or equal to a predetermined value.

[0015] In the water ingress detection method according to claim 5, water ingress is detected when the first exposed conductive portion and the second exposed conductive portion, which are installed inside a groove recessed below the lower end of the battery pack, become conductive through the water that has entered. Therefore, water ingress can be detected before water comes into contact with the battery pack. [Effects of the Invention]

[0016] According to this disclosure, water ingress can be detected before water comes into contact with the battery pack. [Brief explanation of the drawing]

[0017] [Figure 1]It is an exploded perspective view of a power storage device according to a first embodiment of the present disclosure. [Figure 2] It is a sectional view taken along the arrow II-II in FIG. 1. [Figure 3] It is a circuit diagram of an ECU included in the power storage device according to the first embodiment of the present disclosure. [Figure 4] It is a flowchart illustrating the procedure of a water entry detection method according to a second embodiment of the present disclosure.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each figure, members that are the same or corresponding to each other are given the same or similar reference numerals, and duplicate explanations are omitted. Also, the dimensions and ratios in the drawings are exaggerated for the convenience of explanation and may be different from the actual ratios.

[0019] First, referring to FIG. 1, a power storage device 1 according to a first embodiment of the present disclosure will be described. FIG. 1 is an exploded perspective view of the power storage device 1. The power storage device 1 includes a battery pack 10, a lower case 20, an upper case 30, a first detection line 41 (hereinafter referred to as "the first detection line 41"), a second detection line 42 (hereinafter referred to as "the second detection line 42"), and an ECU 50.

[0020] The battery pack 10 typically includes a plurality of power storage cells. The power storage cells can be secondary batteries such as lithium-ion batteries or nickel-metal hydride batteries. The power storage cells may use a liquid electrolyte or a solid electrolyte. In this embodiment, the battery pack 10 formed by integrating a plurality of power storage cells has a rectangular plate-like appearance. The battery pack  10 may be connected to a power storage device (not shown) via a conductive member.

[0021] The lower case 20 cooperates with the upper case 30 to form a space for accommodating the battery pack 10. The lower case 20 is a container disposed below the battery pack 10. The lower case 20 is typically formed of a steel plate or the like, but may be formed of a material other than the steel plate according to the use of the power storage device 1 or the like.

[0022] The lower case 20 has a mounting surface 21 on which the battery pack 10 is placed. The mounting surface 21 typically has a size that encompasses the battery pack 10 and is a rectangle having the same size as the planar shape of the battery pack 10 in the present embodiment, but may be larger than the planar shape of the battery pack 10. The mounting surface 21 is typically flat, but may have protrusions that support the battery pack 10 at multiple points or lines. The battery pack 10 is typically directly placed on the mounting surface 21, but may be indirectly placed via other members such as a waterproof sheet. The mounting surface 21 may be provided with positioning claws (not shown) for determining the planar position of the placed battery pack 10.

[0023] In the present embodiment, the lower case 20 is provided with a lower flange 22 at the outer peripheral portion. The lower flange 22 corresponds to the first flange portion. The lower flange 22 is provided over the entire outer circumference outside the mounting surface 21. A groove portion 23 is formed in the lower flange 22. The groove portion 23 is recessed below the lower end (i.e., the lowermost portion) of the battery pack 10 placed on the mounting surface 21. In the present embodiment, the groove portion 23 is formed over the entire periphery outside the mounting surface 21. In the present embodiment, the groove portion 23 is formed in the lower flange 22 at the boundary with the mounting surface 21, but may be formed in the lower flange 22 at a portion separated outward from the boundary with the mounting surface 21.

[0024] Figure 2 illustrates the cross-sectional shape of the groove 23. Figure 2 is a cross-sectional view taken along the line II-II in Figure 1. The top and bottom of the paper in Figure 2 correspond to the actual top and bottom. In this embodiment, the groove 23 narrows in width as it moves downward and has a curved lower end, but it is not limited to this shape; for example, it may have a shape in which the width remains constant as it moves downward and has a flat lower end. The groove 23 has a pair of opposing wall surfaces 24 formed in the direction of the inside of the lower case 20 and in the direction of the outer circumference. In this embodiment, the pair of wall surfaces 24 are inclined such that the distance between them decreases as they move downward. When the groove 23 is referred to in the following description, please refer to Figure 2 as appropriate.

[0025] The upper case 30 works in cooperation with the lower case 20 to form a space for housing the battery pack 10. The upper case 30 is a container positioned above the battery pack 10. Like the lower case 20, the upper case 30 is typically made of steel plate or the like, but may be made of a material other than steel plate depending on the application of the energy storage device 1. In this embodiment, the upper case 30 is provided with an upper flange 32 on its outer circumference. The upper flange 32 is the part that joins with the lower flange 22 and corresponds to a second flange portion. When the lower flange 22 and the upper flange 32 are butted together facing each other around the entire circumference, a space capable of housing the battery pack 10 is formed between the lower case 20 and the upper case 30.

[0026] The first detection wire 41 is provided to work in cooperation with the second detection wire 42 to detect when water enters the groove 23. The first detection wire 41 has a portion located inside the groove 23. In this embodiment, the first detection wire 41 has a portion located around the entire circumference of the groove 23, which is formed around the entire outer circumference of the mounting surface 21. In this embodiment, the portion of the first detection wire 41 located inside the groove 23 is attached to one wall surface 24 at the lower part of the groove 23, as shown in Figure 2. Here, the lower part of the groove 23 means below half the height of the depth of the groove 23. In this embodiment, the first detection wire 41 is located downward from the upper surface of the lower flange 22 at a position of 1 / 2 to 2 / 3 of the depth of the groove 23. Typically, the first detection wire 41 has a basic configuration in which an insulator such as rubber is present as a covering over an exposed wire. The exposed wire in the first detection wire 41 is the conductive part through which current flows.

[0027] The first detection wire 41 has a first exposed portion 41E in the part located inside the groove 23. The first exposed portion 41E is the part of the wire that is exposed when a detection hole is made in the insulator covering the exposed wire, and corresponds to the first exposed conductive portion. In this embodiment, a plurality of first exposed portions 41E are formed at predetermined intervals in the direction in which the groove 23 extends along the outer circumference of the mounting surface 21 (hereinafter referred to as the "circumferential direction" of the groove 23). The predetermined interval of the first exposed portions 41E should be determined from the viewpoint of being able to detect as quickly as possible if water enters any part of the groove 23. The plurality of first exposed portions 41E are typically formed at a constant interval (i.e., equal intervals), but the distance between adjacent first exposed portions 41E may differ depending on the location. Each first exposed portion 41E should be large enough so that, if water is present outside the first detection wire 41, that water can reach the wire covered by the insulator.

[0028] The second detection wire 42 is provided to work in cooperation with the first detection wire 41 to detect when water has entered the groove 23. The second detection wire 42 is typically constructed in the same way as the first detection wire 41, and is typically insulated from an exposed wire. Like the first detection wire 41, the second detection wire 42 has a portion located inside the groove 23, and in this embodiment, a portion located around the entire circumference of the groove 23 formed on the outside of the mounting surface 21. In this embodiment, the portion of the second detection wire 42 located inside the groove 23 is attached to the wall surface 24 opposite to the wall surface 24 to which the first detection wire 41 is attached, at the bottom of the groove 23. The second detection wire 42 is typically located at the same height as the first detection wire 41, but may be located at a different height.

[0029] The second detection wire 42 has a second exposed portion 42E in the part located inside the groove 23. The second exposed portion 42E is the part of the wire that is exposed when a detection hole is made in the insulator covering the exposed wire, and corresponds to a second exposed conductive portion. The second exposed portion 42E performs the same function as the first exposed portion 41E of the first detection wire 41, and multiple second exposed portions 42E are formed with the same configuration as the first exposed portion 41E. It is preferable that each second exposed portion 42E is positioned as close as possible to each first exposed portion 41E, for example, so that their circumferential positions in the groove 23 are aligned.

[0030] The portions of the first detection wire 41 and the second detection wire 42 that are not located in the groove 23 extend out of the lower case 20 and are connected to the ECU 50. The first detection wire 41 and the second detection wire 42 may also be connected to an energy storage device (not shown). The portions of the first detection wire 41 and the second detection wire 42 other than those located in the groove 23, i.e., the portions that leave the groove 23 and are connected to the ECU 50 or an energy storage device (not shown), are entirely covered with an insulator, and there are no exposed wires.

[0031] The ECU (Electronic Control Unit) 50 is a device controlled using electronic circuits and corresponds to an electronic device. The ECU 50 is connected to a first detection line 41 and a second detection line 42. The ECU 50 measures the resistance or potential difference between the first detection line 41 and the second detection line 42. The ECU 50 estimates that water has entered the inside of the energy storage device 1 when the measured resistance or potential difference falls below a predetermined value. Here, the predetermined value is the potential difference when there is a high probability that the first detection line 41 and the second detection line 42 are conducting, and is, for example, a value close to 0 or a value corresponding to the resistance of water. When the ECU 50 estimates that water has entered the inside of the energy storage device 1, it may, for example, transmit a signal to notify the user. Examples of notifying the user include transmitting an alarm signal to a higher-level control panel (not shown), sending an email containing the notification details to the user via a network, or emitting an alarm sound or light.

[0032] Figure 3 illustrates the internal electronic circuit of the ECU 50. The first detection line 41 is connected to the power supply 51 inside the ECU 50. The second detection line 42 is connected to ground. In this case, if the first detection line 41 and the second detection line 42 are insulated, the potential of the first detection line 41 will be the potential of the power supply 51. On the other hand, if the first detection line 41 and the second detection line 42 are conductive, the potential of the first detection line 41 will be the ground potential. One example of when the first detection line 41 and the second detection line 42 are conductive is when water accumulated inside the groove 23 comes into contact with the first exposed part 41E and the second exposed part 42E, causing the first detection line 41 and the second detection line 42 to come into contact via the water accumulated inside the groove 23. This makes it possible to detect the intrusion of water that contains electrolytes such as rainwater or cooling water and conducts electricity.

[0033] Next, with reference to Figure 4, a water ingress detection method according to a second embodiment of this disclosure will be described. Figure 4 is a flowchart illustrating the procedure of the water ingress detection method. The following description is for the purpose of describing the water ingress detection method in the aforementioned energy storage device 1, and also serves as a description of the operation of the energy storage device 1. When the configuration of the energy storage device 1 is referred to in the following description, please refer to Figures 1 to 3 as appropriate. Note that the water ingress detection method according to the second embodiment of this disclosure is applicable to devices other than the energy storage device 1.

[0034] When water ingress detection is initiated, the ECU 50 determines whether the potential of the first detection line 41 is the potential of the power supply 51 (S1). If there is no water inside the energy storage device 1 and no water inside the groove 23, then normally the first detection line 41 and the second detection line 42 are not conducting through the first exposed part 41E and the second exposed part 42E, and the potential of the first detection line 41 is the potential of the power supply 51. In this embodiment, the potential difference between the first detection line 41 and the second detection line 42 is the potential of the power supply 51.

[0035] If the potential of the first detection line 41 in step S1 is the potential of the power supply 51 (YES in step S1), the ECU 50 determines whether the potential difference between the first detection line 41 and the second detection line 42 is less than or equal to a predetermined value (S2). If there is no water inside the groove 23, the above potential difference usually exceeds the predetermined value. If the potential difference is not less than or equal to the predetermined value (NO in step S2), the process returns to step S2.

[0036] In step S2, when water enters the inside of the energy storage device 1, this water enters the lower part of the lower case 20, i.e., the groove 23. Since the groove 23 is formed outside the mounting surface 21, the water that enters the inside of the energy storage device 1 enters the groove 23 before reaching the battery pack 10. When water enters the inside of the groove 23 and the water level rises inside the groove 23, and the water inside the groove 23 comes into contact with the first exposed part 41E and the second exposed part 42E, the first detection line 41 and the second detection line 42 become conductive through the water inside the groove 23. When the first detection line 41 and the second detection line 42 become conductive, the potential difference between the first detection line 41 and the second detection line 42 decreases. The ECU 50 estimates that water has entered the inside of the energy storage device 1, i.e., water ingress has occurred, if the potential difference between the first detection line 41 and the second detection line 42 is less than or equal to a predetermined value (YES in step S2) (S3).

[0037] In this embodiment, if the ECU 50 estimates that water has entered the battery, it notifies the user (S4). Upon receiving the notification, the user can avoid water contact with the battery pack 10 by inspecting the energy storage device 1 in question. In this embodiment, since the groove 23 is formed around the entire perimeter outside the mounting surface 21, the amount of water that can be held inside the groove 23 can be increased compared to when it is formed only partially. Also, since the first exposed portion 41E and the second exposed portion 42E are located at the bottom of the inside of the groove 23, a time lag can be created between the time the ECU 50 detects a change in potential difference and the time the water accumulating in the groove 23 overflows. This allows the user to have time to inspect the energy storage device 1 after receiving the notification. In this embodiment, even if the potential of the first detection line 41 is not the potential of the power supply 51 in step S1 (NO in step S1), the ECU 50 still notifies the user (S4).

[0038] As described above, according to the first embodiment of the energy storage device 1 and the second embodiment of the water ingress detection method, water ingress can be detected before water comes into contact with the battery pack 10.

[0039] In the above description, it is assumed that the lower case 20 has a lower flange 22 and the upper case 30 has an upper flange 32, but the lower flange 22 and upper flange 32 do not have to be provided. In this case, the lower case 20 and upper case 30 may have a known fitting structure. Also, if the lower flange 22 is not provided, the groove 23 may be formed on the inside of the outer edge of the lower case 20 outside the mounting surface 21.

[0040] In the above description, it was assumed that the groove 23 is formed over the entire perimeter of the mounting surface 21. However, it may also be formed partially around the perimeter of the mounting surface 21. If there are multiple grooves 23 partially formed around the perimeter of the mounting surface 21, the first exposed portion 41E and the second exposed portion 42E may be located in all of the multiple grooves 23, or in some of them.

[0041] In the above description, it is assumed that the first detection wire 41 and the second detection wire 42 are installed around the entire circumference of the groove 23 formed around the mounting surface 21, and that the first detection wire 41 has multiple first exposed portions 41E provided at predetermined intervals, and the second detection wire 42 has multiple second exposed portions 42E provided at predetermined intervals. However, the entirety of both or either of the first detection wire 41 and the second detection wire 42 in the portion located inside the groove 23 may be exposed without insulation.

[0042] In the above description, the first exposed portion 41E and the second exposed portion 42E are assumed to be located at the bottom of the groove 23, but at least one of them may be located at the top inside the groove 23. Here, the top of the groove 23 means above half the height of the groove 23's depth, and may be at a position 1 / 3 to 1 / 2 of the groove 23's depth downward from the top surface of the lower flange 22. In this way, the probability of the first exposed portion 41E and the second exposed portion 42E coming into contact with conductive material that has accidentally entered the groove 23 can be reduced, and false detection of water ingress can be suppressed.

[0043] In the above explanation, the water ingress detection method is assumed to have occurred inside the energy storage device 1 when the potential difference between the first detection line 41 and the second detection line 42 is below a predetermined value. Alternatively, it may be assumed that water ingress has occurred inside the energy storage device 1 when the resistance between the first detection line 41 and the second detection line 42 is below a predetermined value. [Explanation of Symbols]

[0044] 1. Energy storage device 10 battery packs 20 Lower Cases 21 Mounting surface 22 Lower flange (first flange section) 23 Groove 30 Upper Case 32 Upper flange (second flange section) 41. First detection line (first detection line) 41E First exposed portion (first exposed conductive portion) 42 Second detection line (second detection line) 42E Second exposed section (second exposed conductive section) 50 ECU (electronic equipment)

Claims

1. Battery pack and A lower case having a mounting surface on which the battery pack is directly or indirectly placed, and a groove formed on the outside of the aforementioned mounting surface that is recessed below the lower end of the battery pack, A first detection wire having a first exposed conductive portion in which a conductive portion is exposed, wherein the first exposed conductive portion is installed inside the groove, A second detection wire having a second exposed conductive portion in which a conductive portion is exposed, wherein the second exposed conductive portion is installed inside the groove at a predetermined distance from the first exposed conductive portion, An electronic device to which the first detection line and the second detection line are connected, the electronic device for measuring the resistance or potential difference between the first detection line and the second detection line, A power storage device equipped with the following features.

2. The upper case, which works in cooperation with the lower case to house the battery pack inside, The lower case has a first flange portion, The upper case has a second flange portion that fits with the first flange portion, The groove is formed in the first flange portion. The energy storage device according to claim 1.

3. The groove portion is formed around the entire perimeter outside the surface described above. The first detection line and the second detection line are each arranged around the entire circumference of the groove. The first exposed conductive portion and the second exposed conductive portion are each provided in multiple quantities. The energy storage device according to claim 1 or claim 2.

4. Both the first exposed conductive portion and the second exposed conductive portion are located in the lower part of the inside of the groove. The energy storage device according to claim 1 or claim 2.

5. The resistance or potential difference between a first detection wire, which has a first exposed conductive portion with an exposed conductive portion, and a second detection wire, which has a second exposed conductive portion with an exposed conductive portion, arranged at a predetermined distance from the first exposed conductive portion, is measured within a groove formed on the outside of the mounting surface on which the battery pack is directly or indirectly mounted in the lower case, recessed below the lower end of the battery pack. If the measured resistance or potential difference is less than or equal to a predetermined value, it is presumed that water has entered the groove. Water ingress detection method.

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