Protective elements and battery pack

Abstract

To stabilize a fixing state of a fusing member and block a current path safety and quickly even if the fusing member generates heat over a long time.SOLUTION: A protection element 1 includes: a case 28; a fuse element 2; a fusing member 3 which is connected to at least one surface of the fuse element 2 and fuses the fuse element 2; and a fixing member 8 which is provided on an inner surface of the case 28 and contacts with the fusing member 3 to inhibit swinging of the fusing member 3. The fusing member 3 includes: an insulation substrate 4; and a heating element 5 formed on the insulation substrate 4. The insulation substrate 4 is connected to the fuse element 2 by a joint material 9 which is softened by heat generated by the heating element 5.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present technology relates to a protection element for interrupting a current path and a battery pack using the same.

Background Art

[0002] Many secondary batteries that can be charged and repeatedly used are processed into battery packs and provided to users. Particularly in lithium-ion secondary batteries with high weight energy density, in order to ensure the safety of users and electronic devices, generally, several protection circuits such as overcharge protection and over-discharge protection are built into the battery pack, and it has a function of interrupting the output of the battery pack in a predetermined case.

[0003] In many electronic devices using lithium-ion secondary batteries, the overcharge protection or over-discharge protection operation of the battery pack is performed by turning on / off the output using a FET switch built into the battery pack. However, if the FET switch is short-circuited and damaged for some reason, a lightning surge or the like is applied, a momentary large current flows, or the output voltage abnormally decreases or, conversely, outputs an excessive abnormal voltage due to the life of the battery cell, the battery pack and the electronic device must be protected from accidents such as ignition. Therefore, in any possible abnormal state, a protection element composed of a fuse element having a function of interrupting the current path by an external signal is used to safely interrupt the output of the battery cell.

[0004] As such a protection element for a protection circuit for lithium-ion secondary batteries and the like, a structure is used in which a heating element is provided inside the protection element, and the heating of the heating element melts a soluble conductor on the current path.

[0005] The applications of lithium-ion secondary batteries have been expanding in recent years, with their adoption beginning in applications requiring higher currents, such as power tools like electric screwdrivers, transportation equipment like hybrid cars, electric vehicles, and electric-assist bicycles, and drones. In these applications, particularly during startup, large currents of several tens of amps to over 100 amps may flow. There is a need for protective elements that can handle such high current capacities.

[0006] To realize a protective element that can handle such large currents, a protective element has been proposed that uses a fusible conductor with an increased cross-sectional area, and connects an insulating substrate with a heating element formed on its surface to this fusible conductor.

[0007] Figure 27 is a plan view showing an example of the configuration of a conventional protective element, Figure 28 is a cross-sectional view of the conventional protective element shown in Figure 27 along the line D-D', and Figure 29 is a cross-sectional view of the conventional protective element shown in Figure 27 along the line E-E'. The protective element 100 shown in Figures 27 to 29 comprises a fuse element 101 and a pair of cutting members 102 that melt the fuse element 101.

[0008] Figure 30 shows a cutting member, where (A) is a plan view showing the surface side of the insulating substrate on which the heating element is provided, and (B) is a bottom view showing the back side of the insulating substrate in contact with the fuse element 101. Each cutting member 102 has an insulating substrate 103, a heating element 104 formed on the surface side of the insulating substrate 103, an insulating layer 105 covering the heating element 104, a heating element lead electrode 106 connected to the heating element 104 and superimposed on the heating element 104 via the insulating layer 105, a holding electrode 107 formed on the back surface of the insulating substrate 103 to hold the molten conductor of the fuse element 101 when the fuse element 101 is cut, and a through hole 108 that penetrates the insulating substrate 103 and connects the heating element lead electrode 106 and the holding electrode 107.

[0009] One end of the heating element 104 is connected to the heating element power supply electrode 110. The heating element power supply electrode 110 is connected via castellation to an external connection electrode 110a formed on the back surface of the insulating substrate 103. As shown in Figure 29, the external connection electrode 110a is connected to a third electrode terminal 113 by a bonding material such as solder paste 114. The heating element 104 is then connected to an external circuit equipped with a power supply via the heating element power supply electrode 110, the external connection electrode 110a, and the third electrode terminal 113, and is capable of receiving power from the external circuit.

[0010] The fuse element 101 is connected to first and second electrode terminals 111 and 112, which are connected to an external circuit, by a bonding material such as solder paste 114. The fuse element 101 is also connected to a retaining electrode 107 and an auxiliary electrode 109 formed on the back surface of the insulating substrate 103 by a bonding material such as solder paste 114.

[0011] When the heating element 104 is energized and heated, the fuse element 101 is melted by the heat, and the molten conductor 101a is attracted to the heating element lead electrode 106 side through the through hole 108. As a result, the fuse element 101 is melted between the holding electrode 107 and the auxiliary electrode 109, and the electrical connection between the first electrode terminal 111 and the second electrode terminal 112 is interrupted. [Prior art documents] [Patent Documents]

[0012] [Patent Document 1] Japanese Patent Publication No. 2021-34362 [Overview of the project] [Problems that the invention aims to solve]

[0013] In conventional structures like the protection element 100, when used in protection circuits for high-voltage, high-current applications such as electric vehicles, a fuse element 101 with a wider cross-sectional area and increased volume to accommodate the high current is used. When the protection element 100 is activated, a high voltage is applied to the heating element 104 to melt the fuse element 101, generating a lot of heat and extending the time until melting. As a result, the extended heating time by the heating element 104 causes excess heat to accumulate on the insulating substrate 103. This makes the fixing state of the melting member 102, which is fixed to the front and back surfaces of the fuse element 101 by solder paste 114, prone to instability.

[0014] For example, as shown in Figure 31, if the insulating substrate 103 of the cutting member 102 tilts and the holding electrode 107, which was in surface contact with the front and back surfaces of the fuse element 101, separates from the fuse element 101, the heat from the heating element 104 cannot be transferred to the fuse element 101, preventing the fuse from cutting and potentially resulting in an uncut fuse (Figure 32).

[0015] Therefore, the objective of this technology is to provide a protective element and a battery pack using the same that can stabilize the fixed state of the cutting element and safely and quickly interrupt the current path, even when the cutting element generates heat over a long period of time. [Means for solving the problem]

[0016] To solve the above-mentioned problems, the protective element according to this technology comprises a case, a fuse element, a cutting member connected to at least one surface of the fuse element and melting the fuse element, and a fixing member provided on the inner surface of the case and suppressing the swinging of the cutting member by contacting the cutting member, wherein the cutting member comprises an insulating substrate and a heating element formed on the insulating substrate, and the insulating substrate is connected to the fuse element by a bonding material that softens due to the heat generated by the heating element. The fixing member is provided with an intermediate material at the part that comes into contact with the cutting member. It is something that exists.

[0017] In addition, the battery pack according to the present technology includes one or more battery cells and a protection element connected on the charge / discharge path of the battery cell to cut off the charge / discharge path, and the protection element is the protection element described above.

Advantages of the Invention

[0018] According to the present technology, a fixing member is provided on the inner surface of the case, and the rocking of the fusing member is suppressed by the fixing member coming into contact with the fusing member. Thereby, even when the bonding material softens and the fixing state of the fusing member with respect to the fuse element becomes unstable, the inclination of the insulating substrate can be suppressed. Therefore, the fixing state of the fusing member can be stabilized, the heat of the heating element can be surely transmitted to the fuse element, and the current path can be interrupted safely and promptly.

Brief Description of the Drawings

[0019] [Figure 1] FIG. 1 is a plan view of a protection element to which the present technology is applied. [Figure 2] FIG. 2 is a cross-sectional view taken along line D-D' of the protection element shown in FIG. 1. [Figure 3] FIG. 3 is a cross-sectional view taken along line E-E' of the protection element shown in FIG. 1. [Figure 4] FIG. 4 is a view showing a fusing member, (A) is a plan view showing the front surface of the insulating substrate, and (B) is a bottom view showing the back surface of the insulating substrate. [Figure 5] FIG. 5 is a view showing a state where the fuse element is blown in the protection element, (A) is a plan view showing the front surface of the insulating substrate, and (B) is a plan view showing the back surface side of the insulating substrate and the blown fuse element. [Figure 6] FIG. 6 is a view showing a state where the fuse element is blown in the protection element to which the present technology is applied, (A) is a cross-sectional view taken along line A-A' of the fusing member shown in FIG. 5, and (B) is a cross-sectional view taken along line B-B' of the fusing member shown in FIG. 5. [Figure 7]FIG. 7 is a view showing the upper case and the lower case, (A) is a plan view of the upper case, (B) is a plan view of the lower case, (C) is a cross-sectional view taken along the line F-F' of the upper case shown in (A), and (D) is a cross-sectional view taken along the line G-G' of the lower case shown in (B). [Figure 8] FIG. 8 is a plan view showing the lower case that supports the first to third electrode terminals. [Figure 9] FIG. 9 is a circuit diagram of the protection element to which the present technology is applied. [Figure 10] FIG. 10 is a cross-sectional view showing a state in which the fuse element is blown in the protection element to which the present technology is applied. [Figure 11] FIG. 11 is a cross-sectional view of the fuse element. [Figure 12] FIG. 12 is a circuit diagram showing a configuration example of the battery pack. [Figure 13] FIG. 13 is a view showing the upper case and the lower case of the protection element according to the modification, (A) is a plan view of the upper case, (B) is a plan view of the lower case, (C) is a cross-sectional view taken along the line H-H' of the upper case shown in (A), and (D) is a cross-sectional view taken along the line I-I' of the lower case shown in (B). [Figure 14] FIG. 14 is a cross-sectional view showing a protection element in which a plurality of fixing members made of columnar members are formed on each inner surface side of the upper case and the lower case. [Figure 15] FIG. 15 is a cross-sectional view showing a protection element in which a plurality of fixing members made of columnar members are formed on each inner surface side of the upper case and the lower case. [Figure 16] FIG. 16 is a view showing the upper case and the lower case of the protection element according to the modification, (A) is a plan view of the upper case, (B) is a plan view of the lower case, (C) is a cross-sectional view taken along the line J-J' of the upper case shown in (A), and (D) is a cross-sectional view taken along the line K-K' of the lower case shown in (B). <​​​Figure 18 shows the upper and lower cases of the protective element according to a modified example, where (A) is a plan view of the upper case, (B) is a plan view of the lower case, (C) is an N-N' cross-sectional view of the upper case shown in (A), and (D) is an O-O' cross-sectional view of the lower case shown in (B). [Figure 19] Figure 19 shows the upper and lower cases of the protective element according to a modified example, where (A) is a plan view of the upper case, (B) is a plan view of the lower case, (C) is a P-P' cross-sectional view of the upper case shown in (A), and (D) is a Q-Q' cross-sectional view of the lower case shown in (B). [Figure 20] Figure 20 shows the upper and lower cases of the protective element according to a modified example, where (A) is a plan view of the upper case, (B) is a plan view of the lower case, (C) is an R-R' cross-sectional view of the upper case shown in (A), and (D) is an S-S' cross-sectional view of the lower case shown in (B). [Figure 21] Figure 21 is a cross-sectional view showing a protective element in which a block-shaped member having a support surface facing the main surface of the insulating substrate is provided as a fixing member. [Figure 22] Figure 22 is a cross-sectional view showing a protective element in which a block-shaped member having a support surface facing the main surface of the insulating substrate is provided as a fixing member. [Figure 23] Figure 23 shows the upper and lower cases of the protective element according to a modified example, where (A) is a plan view of the upper case, (B) is a plan view of the lower case, (C) is a T-T' cross-sectional view of the upper case shown in (A), and (D) is a U-U' cross-sectional view of the lower case shown in (B). [Figure 24] Figure 24 shows the upper and lower cases of the protective element according to a modified example, where (A) is a plan view of the upper case, (B) is a plan view of the lower case, (C) is a V-V' cross-sectional view of the upper case shown in (A), and (D) is a W-W' cross-sectional view of the lower case shown in (B). [Figure 25] Figure 25 is a cross-sectional view showing a protective element that serves as a fixing member, provided on the inner surface of the case and having a support piece formed to support the outer edge of the insulating substrate. [Figure 26]Figure 26 is a cross-sectional view showing a protective element that serves as a fixing member, provided on the inner surface of the case and having a support piece formed to support the outer edge of the insulating substrate. [Figure 27] Figure 27 is a plan view of the protective element. [Figure 28] Figure 28 is a cross-sectional view taken along line D-D' of the protective element shown in Figure 27. [Figure 29] Figure 29 is a cross-sectional view of the protective element shown in Figure 27, along the line E-E'. [Figure 30] Figure 30 shows the cutting member of the protective element shown in Figure 27, where (A) is a plan view showing the surface of the insulating substrate and (B) is a bottom view showing the back surface of the insulating substrate. [Figure 31] Figure 31 is a cross-sectional view showing the protective element shown in Figure 27, where the cutting member oscillates, causing the insulating substrate to tilt, and the retaining electrode, which was in surface contact with the front and back surfaces of the fuse element, separates from the fuse element. [Figure 32] Figure 32 is a cross-sectional view showing the state in which a portion of the fuse element remains uncut in the protective device shown in Figure 27. [Modes for carrying out the invention]

[0020] The protective elements and battery packs to which this technology is applied will be described in detail below with reference to the drawings. It should be noted that this technology is not limited to the embodiments described below, and various modifications are possible within the scope of the gist of this technology. Furthermore, the drawings are schematic, and the proportions of dimensions may differ from those of reality. Specific dimensions should be determined by referring to the following explanation. It should also be noted that there may be differences in the relationships and proportions of dimensions between different drawings.

[0021] As shown in Figures 1 to 3, the protective element 1 to which this technology is applied includes a case 28, a fuse element 2, a cutting member 3 connected to at least one surface of the fuse element 2 and melting the fuse element 2, and a fixing member 8 provided on the inner surface of the case 28 and suppressing the swinging of the cutting member 3 by contacting it. Figure 1 is a plan view of the protective element 1, Figure 2 is a cross-sectional view of the protective element 1 shown in Figure 1 along line D-D', and Figure 3 is a cross-sectional view of the protective element 1 shown in Figure 1 along line E-E'.

[0022] Figure 4 shows the cutting member 3, where (A) is a plan view showing the surface 4a of the insulating substrate 4, and (B) is a bottom view showing the back surface 4b of the insulating substrate 4. The cutting member 3 has an insulating substrate 4, a heating element 5 formed on the surface 4a side of the insulating substrate 4, an insulating layer 6 covering the heating element 5, and a heating element lead electrode 7 connected to the heating element 5 and superimposed on the heating element 5 via the insulating layer 6.

[0023] Furthermore, on the back surface 4b of the insulating substrate 4 opposite to the front surface 4a, a retaining electrode 10 is formed to hold the molten conductor 2a of the fuse element 2 when the fuse element 2 melts, and the heat-generating electrode 7 and the retaining electrode 10 are continuous through a through-hole 11 that penetrates from the insulating substrate 4 to the heat-generating electrode 7.

[0024] The fuse element 2 is connected to the retaining electrode 10 by a conductive bonding material such as connecting solder 9, which softens when heated. The fuse element 2 is also connected to first and second electrode terminals 21 and 22, both of which are connected to an external circuit, by a bonding material such as connecting solder 9.

[0025] According to this protective element 1, a fixing member 8 is provided on the inner surface of the case 28, and this fixing member 8 comes into contact with the cutting member 3, thereby suppressing the oscillation of the cutting member 3. As a result, even when the heat generated by the heating element 5 during the fuse element 2 blows causes the connecting solder 9 to soften and the fixing state of the cutting member 3 to the fuse element 2 becomes unstable, the tilting of the insulating substrate 4 is suppressed.

[0026] In other words, with the protection element 1, the retaining electrode 10, which was in surface contact with the fuse element 2, does not separate from the fuse element 2, and the heat from the heating element 5 can be reliably transferred to the fuse element 2. Therefore, even when a large fuse element 2 that can handle a large current is used, and a considerable amount of high heat is generated for a considerable amount of time to melt the fuse element 2, the fixed state of the melting member 3 can be stabilized, and the current path can be safely and quickly interrupted.

[0027] The following describes in detail the configuration of the fusible member 3 of the protective element 1 and the fuse element 2.

[0028] [Cutting member] [Insulating substrate] The cutting member 3 includes an insulating substrate 4. The insulating substrate 4 is formed from an insulating material such as alumina, glass ceramics, mullite, or zirconia. In addition, the insulating substrate 4 may be made from materials used for printed circuit boards, such as glass epoxy substrates or phenolic substrates. A heating element 5 is formed on the surface 4a of the insulating substrate 4.

[0029] In this invention, as shown in Figure 4(A), the surface of the insulating substrate 4 on which the heating element 5 is formed is the front surface 4a, and as shown in Figure 4(B), the surface opposite to the front surface 4a is the back surface 4b. The insulating substrate 4 also has through holes 11 that connect the heating element lead-out electrodes 7 formed on the front surface 4a (described later) and the retaining electrodes 10 formed on the back surface 4b (described later).

[0030] [Heating element] The heating element 5 is a conductive material with relatively high resistance that generates heat when current is passed through it, and is made of materials such as nichrome, W, Mo, Ru, or materials containing these materials. The heating element 5 can be formed by mixing powdered alloys or compositions or compounds of these materials with a resin binder or the like to make a paste, forming a pattern on an insulating substrate 4 using screen printing technology, and then firing it.

[0031] In the protective element 1, two heating elements 5 are formed in parallel on the surface 4a of the insulating substrate 4. One end of each heating element 5 is connected to a heating element power supply electrode 12, and the other end is connected to a heating element electrode 14. The heating element power supply electrode 12 is an electrode that is connected to one end of the heating element 5 and serves as a power supply terminal to the heating element 5, and is continuous with an external connection electrode 12a formed on the back surface 4b of the insulating substrate 4 via castellation. In addition, each heating element 5 is covered with an insulating layer 6, and a heating element lead electrode 7 formed on the insulating layer 6 is superimposed on it.

[0032] The external connection electrode 12a is connected to a third electrode terminal 23 that is connected to an external circuit by a conductive bonding material such as solder 9, which softens when heated by the heat generated by the heating element 5. This connection allows the external circuit to be connected to a power supply and power to the heating element 5. The heating element electrode 14 is connected to a heating element lead electrode 7, which will be described later.

[0033] The heating element power supply electrode 12 and the heating element electrode 14 are each formed by a conductive pattern of Ag, Cu, or the like. Furthermore, it is preferable that the surfaces of the heating element power supply electrode 12 and the heating element electrode 14 are coated with a film such as Ni / Au plating, Ni / Pd plating, or Ni / Pd / Au plating by known methods such as plating. This allows the protective element 1 to prevent oxidation of the heating element power supply electrode 12 and the heating element electrode 14, and to prevent fluctuations in the rating due to an increase in conductivity resistance.

[0034] Furthermore, it is preferable to provide a restricting wall (not shown) on the heating element power supply electrode 12 to prevent the connecting solder 9 connecting the external connection electrode 12a and the third electrode terminal 23 from melting during reflow mounting, etc., and spreading onto the heating element power supply electrode 12 via castellation. The restricting wall can be formed using an insulating material that does not wet to solder, such as glass, solder resist, or insulating adhesive, and can be formed on the heating element power supply electrode 12 by printing or the like. By providing a restricting wall, it is possible to prevent the molten connecting solder 9 from spreading to the heating element power supply electrode 12 and maintain connectivity between the protective element 1 and the external circuit board.

[0035] The insulating layer 6 is provided to protect and insulate the heating element 5, and is made of, for example, a glass layer. The insulating layer 6 is formed to be thin, for example, 10 to 40 μm thick. The insulating layer 6 may also be formed between the surface 4a of the insulating substrate 4 and the heating element 5.

[0036] [Heating element extraction electrode] The heating element lead-out electrode 7 is formed by a conductive pattern of Ag, Cu, etc., similar to the heating element power supply electrode 12 and the heating element electrode 14. Furthermore, it is preferable that the surface of the heating element lead-out electrode 7 is coated with a film such as Ni / Au plating, Ni / Pd plating, or Ni / Pd / Au plating by known methods such as plating.

[0037] The heating element lead electrode 7 is connected at one end to the heating element electrode 14 and is formed on the insulating layer 6, overlapping with the heating element 5 via the insulating layer 6. The heating element lead electrode 7 has a tip portion 7a that extends between the two heating elements 5 in an area where no heating elements 5 are formed, and a base portion 7b that overlaps with the two heating elements 5 and is connected to the heating element electrode 14. When the width direction of the heating element lead electrode 7 is taken perpendicular to the direction of current flow of the heating element 5, the wider portion that overlaps with the two heating elements 5 is the base portion 7b, and the narrower portion that protrudes from the base portion 7b and extends into the area between the two heating elements 5 is the tip portion 7a.

[0038] The heating element lead electrode 7 is provided with a through hole 11 and is electrically and thermally connected to a retaining electrode 10 formed on the back surface 4b of the insulating substrate 4. As a result, the heat from the heating element 5 is transferred to the fuse element 2 via the heating element lead electrode 7, the through hole 11, and the retaining electrode 10, melting the fuse element 2. In addition, the molten conductor 2a of the fuse element 2 is attracted to the through hole 11 and held on the heating element lead electrode 7 (see Figure 5).

[0039] [Holding electrode] On the back surface 4b of the insulating substrate 4, a retaining electrode 10, an auxiliary electrode 15, and an external connecting electrode 12a are formed, which are connected to the fuse element 2 by a connecting material such as connecting solder 9. The retaining electrode 10 is formed in a position opposite the heating element lead electrode 7, which is formed approximately in the center of the surface 4a via the insulating substrate 4. Furthermore, the retaining electrode 10 is continuous with the heating element lead electrode 7 through a through hole 11 that penetrates from the surface of the retaining electrode 10 to the heating element lead electrode 7. As a result, the molten conductor 2a of the molten fuse element 2 is attracted to the heating element lead electrode 7 side through the through hole 11.

[0040] The auxiliary electrode 15, together with the retaining electrode 10, is connected to the fuse element 2 and holds the molten conductor 2a. The auxiliary electrode 15 is formed on both side edges of the insulating substrate 4, with the retaining electrode 10 in between.

[0041] The external connection electrode 12a, the holding electrode 10, and the auxiliary electrode 15 can be formed using known electrode materials such as Ag, Cu, or alloy materials mainly composed of Ag or Cu, by known methods such as screen printing.

[0042] When the fuse element 2 melts, the through-hole 11 attracts the molten conductor 2a of the fuse element 2 through capillary action, reducing the volume of molten conductor 2a held on the holding electrode 10. As a result, even when the amount of melting increases due to the enlargement of the fuse element 2 as a result of the higher rating and higher capacity of the protection element 1, a large amount of molten conductor 2a can be held by the holding electrode 10, the heating element lead electrode 7, and the auxiliary electrode 15, as shown in Figure 6, ensuring that the fuse element 2 is reliably blown.

[0043] The through-hole 11 is formed in a region of the insulating substrate 4 where the heating element 5 is not formed. In the cutting member 3 shown in Figure 4, it is formed in the region between the parallel heating elements 5.

[0044] A conductive layer 24 is formed on the inner surface of the through hole 11. The conductive layer 24 is continuous with the holding electrode 10 and the heating element lead electrode 7. As a result, the holding electrode 10 and the heating element lead electrode 7 are electrically connected via the conductive layer 24. Furthermore, the formation of the conductive layer 24 allows the heat from the heating element 5 to be quickly transferred to the fuse element 2 via the heating element lead electrode 7 and the holding electrode 10.

[0045] Furthermore, the holding electrode 10 supports the fuse element 2, and when the fuse is cut, the molten conductor 2a aggregates. Therefore, the holding electrode 10 and the conductive layer 24 are continuous, making it easier to guide the molten conductor 2a into the through hole 11. In addition, the molten conductor 2a wets and spreads onto the heating element lead-out electrode 7, which is continuous with the conductive layer 24, and is held there (see Figures 5 and 6). As a result, more molten conductor 2a can be attracted and held into the through hole 11 and the heating element lead-out electrode 7, reducing the volume of molten conductor 2a held by the holding electrode 10 and the auxiliary electrode 15, and ensuring reliable cutting.

[0046] The conductive layer 24 can be formed from, for example, copper, silver, gold, iron, nickel, palladium, lead, or tin, or an alloy mainly composed of any of these, and can be formed on the inner surface of the through hole 11 by known methods such as electroplating or printing of conductive paste. Alternatively, the conductive layer 24 may be formed by inserting a plurality of metal wires or an assembly of conductive ribbons into the through hole 11.

[0047] Furthermore, the cutting member 3 may have multiple through holes 11. This increases the heat transfer paths of the heating element 5, allowing heat to be transferred to the fuse element 2 more quickly, and also increases the paths for drawing in the molten conductor 2a of the fuse element 2, allowing for the rapid drawing in more molten conductor 2a and thereby reducing the volume of molten conductor 2a at the cutting site.

[0048] [case] Furthermore, the protective element 1 is protected internally by the case 28 covering the fuse element 2 and the cutting member 3. The case 28 can be formed using insulating materials such as various engineering plastics, thermoplastics, ceramics, or glass epoxy substrates. The case 28 houses the fuse element 2 and the cutting member 3 and has sufficient internal space for the molten conductor 2a to expand spherically and aggregate on the heating element lead electrode 7 when the fuse element 2 melts.

[0049] As shown in Figures 2, 3, and 7, the case 28 is formed by combining an upper case 29 and a lower case 30. Figure 7 shows the upper case 29 and the lower case 30, where (A) is a plan view of the upper case 29, (B) is a plan view of the lower case 30, (C) is a cross-sectional view of the upper case 29 shown in (A) along the line F-F', and (D) is a cross-sectional view of the lower case 30 shown in (B) along the line G-G'. The upper case 29 has a fitting recess 31 formed on the lower surface of its side wall. The lower case 30 has a fitting projection 32 formed on the upper surface of its side wall that fits into the fitting recess 31. The upper and lower cases 29 and 30 are combined by the fitting projection 32 fitting into the fitting recess 31 and fixed together with adhesive.

[0050] As shown in Figure 8, the lower case 30 is formed in a substantially rectangular shape and has a side edge portion 30a on which a fitting projection 32 is formed and which supports the first to third electrode terminals 21 to 23, and a hollow portion 30b on which the fusible member 3 connected to the lower surface of the fuse element 2 is located. The side edge portion 30a supports the first to third electrode terminals 21 to 23 on both the inside and outside of the case 28. The hollow portion 30b houses the fusible member 3 connected to the lower surface of the fuse element 2 and has an internal space on which the molten conductor 2a can wet and spread and aggregate on the heating element lead electrode 7.

[0051] The upper case 29 is formed in a substantially rectangular shape, similar to the lower case 30, and is butted and joined with the lower case 30 to cover the fuse element 2 and the fusible cutting member 3 connected to the upper surface of the fuse element 2. The upper case 29 also has an internal space that allows the molten conductor 2a to wet and spread and aggregate on the heating element lead electrode 7.

[0052] [Fixing components] A fixing member 8 is provided on the inner surface of the case 28 to suppress the swinging of the cutting member 3 by contacting it. The fixing member 8 is supported on the inner surface of the case 28 and protrudes to the vicinity of the cutting member 3. The fixing member 8 contacts the cutting member 3 when the fuse element 2 is blown and the heat generated by the heating element 5 causes the connecting solder 9 to soften, making the fixing state of the cutting member 3 to the fuse element 2 unstable. This suppresses the swinging of the cutting member 3, prevents the holding electrode 10, which was in surface contact with the fuse element 2, from separating from the fuse element 2, and ensures that the heat from the heating element 5 is reliably transferred to the fuse element 2.

[0053] As shown in Figure 3, the fuse cutting member 3 has an external connection electrode 12a provided on one side edge of the insulating substrate 4, which is connected to the third electrode terminal 23 by a connecting material such as connecting solder 9. Furthermore, the connecting solder 9 that connects the fuse element 2 and the retaining electrode 10 in a surface contact state softens as the retaining electrode 10 is heated during the fuse cutting process of the fuse element 2. As a result, the insulating substrate 4 may tilt towards the external connection electrode 12a side, causing the retaining electrode 10 and the fuse element 2 to separate, which may result in insufficient heating of the fuse element 2 (see Figure 31).

[0054] The protective element 1 is provided with a fixed member 8 supported on the inner surface of the case 28, and the oscillation of the cutting member 3 can be suppressed by the fixing member 8 coming into contact with the cutting member 3. Therefore, even when a large fuse element 2 that can handle a large current is used, and a considerable amount of high heat is generated for a considerable amount of time to melt the fuse element 2, the fixing state of the cutting member 3 to the fuse element 2 is stabilized, and the fuse element 2 can be sufficiently heated and melted via the holding electrode 10, thereby safely and quickly interrupting the current path.

[0055] The fixing member 8 can be formed using, for example, various engineering plastics, thermoplastics, etc. Alternatively, the fixing member 8 can be a separate component from the case 28 and fixed to the inner surface of the case 28. Or, the fixing member 8 can be integrally molded with the case 28.

[0056] The fixing member 8 can be formed by a columnar member 17, for example, as shown in Figures 2, 3, and 7. The columnar member 17 protrudes from the top surface of the upper case 29 and the bottom surface of the lower case 30, respectively, and contacts the cutting member 3 connected to one surface and the other surface of the fuse element 2, respectively. The tip of the columnar member 17 may be in contact with the cutting member 3 beforehand, or the tip may be positioned close to the cutting member 3 so as to contact it when the cutting member 3 swings. In addition, there may be one or more columnar members 17 that contact each cutting member 3. The size of the contact surface of the columnar member 17 with the cutting member 3 is set according to the contact position of the cutting member 3.

[0057] Furthermore, the area where the fixing member 8 of the cutting member 3 makes contact is preferably a position that does not hinder the aggregation of the molten conductor 2a, such as the corner of the surface 4a of the insulating substrate 4 or on the insulating layer 6. In particular, as shown in Figures 3 and 7, it is preferable that the fixing member 8 is provided so as to contact the side edge of the insulating substrate 4 opposite to the side edge on which the external connection electrode 12a is formed, and in a position facing the external connection electrode 12a. This effectively prevents the insulating substrate 4 from tilting toward the external connection electrode 12a.

[0058] Furthermore, the fixing member 8 may be provided with an intermediate material (not shown) at the portion that contacts the cutting member 3 to provide buffering and prevent adhesion with the cutting member 3. Examples of intermediate materials include, but are not limited to, rubber, elastic resin, nonwoven fabric, nonwoven fabric impregnated with elastic resin, and inorganic fiber materials. The intermediate material can also be attached to the tip of the fixing member 8 with an adhesive. Alternatively, if the intermediate material is itself adhesive, it can be attached by covering the tip of the fixing member 8. By providing an intermediate material, damage such as contact between the fixing member 8 and the cutting member 3 or adhesion can be prevented, and the performance of both the fixing member 8 and the cutting member 3 can be maintained.

[0059] [Formation process of fused / cut members] In this type of fuse cutter 3, the heating element power supply electrode 12 and heating element electrode 14 are formed on the surface 4a of the insulating substrate 4 using known forming methods such as screen printing, followed by the formation of the heating element 5 and the lamination of the insulating layer 6. Next, the heating element lead electrode 7 is formed. The back surface 4b of the insulating substrate 4 is also formed using known forming methods such as screen printing to form the holding electrode 10, the external connection electrode 12a, and the auxiliary electrode 15. After that, through holes 11 are formed with a drill or the like, and the conductive layer 24 is formed by plating or the like to complete the fuse cutter 3. The holding electrode 10 and the auxiliary electrode 15 of the fuse cutter 3 are connected to the fuse element 2 by connecting solder 9. The fuse element 2 to which the fuse cutter 3 is connected is connected by connecting solder 9 to the first and second electrode terminals 21 and 22 supported on the side edge 30a of the lower case 30. In addition, the external connection electrode 12a of the insulating substrate 4 is connected by connecting solder 9 to the third electrode terminal 23 supported on the side edge 30a of the lower case 30.

[0060] [Fuse element clamping configuration] In the protective element 1 shown in Figure 2, a fuse cutter 3 is connected to one side of the fuse element 2 and to the other side opposite to that side, thereby sandwiching the fuse element 2 between multiple fuse cutters 3. Figure 9 is a circuit diagram of the protective element 1. Each fuse cutter 3 connected to one side and the other side of the fuse element 2 has one end of a heating element 5 connected to the fuse element 2 via heating element lead electrodes 7 and holding electrodes 10 formed on each insulating substrate 4. Furthermore, each fuse cutter 3 has a heating element power supply electrode 12 connected to the other end of the heating element 5, which is connected to a third electrode terminal 23 via a connecting material such as solder 9, and is connected via the third electrode terminal 23 to a power supply provided in an external circuit for heating the heating element 5.

[0061] Furthermore, as shown in Figure 10, when the protective element 1 melts the fuse element 2 due to the heat generated by the heating element 5, the heating elements 5 of each melting member 3, 3 connected to both sides of the fuse element 2 generate heat, heating the fuse element 2 from both sides. Therefore, even when the cross-sectional area of ​​the fuse element 2 is increased to accommodate high-current applications, the protective element 1 can quickly heat and melt the fuse element 2.

[0062] Furthermore, the protective element 1 draws the molten conductor 2a from both sides of the fuse element 2 into the through holes 11 formed in each cutting member 3 and holds it with the heating element lead-out electrode 7. Therefore, even when the cross-sectional area of ​​the fuse element 2 is increased to accommodate high-current applications and a large amount of molten conductor 2a is generated, the protective element 1 can draw it in with the multiple cutting members 3 and reliably melt the fuse element 2. In addition, by drawing in the molten conductor 2a with the multiple cutting members 3, the protective element 1 can melt the fuse element 2 more quickly.

[0063] Even when the fuse element 2 uses a coating structure in which the low-melting-point metal constituting the inner layer is covered with a high-melting-point metal, the protective element 1 can quickly fuse the fuse element 2. That is, even when the heating element 5 generates heat, it takes time for the fuse element 2 covered with a high-melting-point metal to heat up to the temperature at which the high-melting-point metal of the outer layer melts. Here, the protective element 1 is equipped with multiple fuse-cutting members 3 and generates heat in each heating element 5 simultaneously, thereby quickly heating the high-melting-point metal of the outer layer to its melting temperature. Therefore, with the protective element 1, the thickness of the high-melting-point metal layer constituting the outer layer can be increased, and rapid fuse-cutting characteristics can be maintained while further increasing the rating.

[0064] Furthermore, as shown in Figure 2, it is preferable that the protective element 1 has a pair of cutting members 3, 3 facing each other and connected to the fuse element 2. This allows the protective element 1 to simultaneously heat the same location on the fuse element 2 from both sides with the pair of cutting members 3, 3 and to draw in the molten conductor 2a, thereby heating and melting the fuse element 2 more quickly.

[0065] Furthermore, it is preferable that the protective element 1 has holding electrodes 10 and auxiliary electrodes 15 formed on each insulating substrate 4 of the pair of cutting members 3, 3 facing each other via the fuse element 2. This ensures that the pair of cutting members 3, 3 are connected symmetrically, which suppresses imbalances in the load applied to the fuse element 2 from the cutting members 3 during reflow mounting or heating of the fuse element 2, thereby improving resistance to deformation of the fuse element 2 and misalignment of the cutting members 3.

[0066] Furthermore, it is preferable to form the heating element 5 on both sides of the through hole 11 in order to heat the holding electrode 10 and the heating element extraction electrode 7, and to aggregate and attract more molten conductor 2a.

[0067] [Fuse Element 2] The fuse element 2 is mounted between the first and second electrode terminals 21 and 22, and melts due to heat generated by the energization of the heating element 5, or due to self-heating (Joule heating) caused by current exceeding the rated current, thereby interrupting the current path between the first electrode terminal 21 and the second electrode terminal 22.

[0068] The fuse element 2 can be any conductive material that melts due to the heat generated by the energization of the heating element 5 or due to an overcurrent condition. For example, in addition to SnAgCu-based Pb-free solder, BiPbSn alloy, BiPb alloy, BiSn alloy, SnPb alloy, PbIn alloy, ZnAl alloy, InSn alloy, PbAgSn alloy, etc. can be used.

[0069] Furthermore, the fuse element 2 may be a structure containing a high-melting-point metal and a low-melting-point metal. For example, as shown in Figure 11, the fuse element 2 is a laminated structure consisting of an inner layer and an outer layer, with a low-melting-point metal layer 26 as the inner layer and a high-melting-point metal layer 27 laminated on the low-melting-point metal layer 26 as the outer layer. The fuse element 2 is connected to the first and second electrode terminals 21, 22, the retaining electrode 10, and the auxiliary electrode 15 via a joining material such as connecting solder 9.

[0070] The low-melting-point metal layer 26 is preferably solder or a metal mainly composed of Sn, and is a material commonly called "Pb-free solder". The melting point of the low-melting-point metal layer 26 does not necessarily need to be higher than the temperature of the reflow oven, and may melt at around 200°C. The high-melting-point metal layer 27 is a metal layer laminated on the surface of the low-melting-point metal layer 26, and is, for example, a metal mainly composed of Ag or Cu, or one of these, and has a high melting point that does not melt even when the connection between the first and second electrode terminals 21, 22, the holding electrode 10 and the auxiliary electrode 15 and the fuse element 2 is performed by reflow.

[0071] Such a fuse element 2 can be formed by depositing a high-melting-point metal layer onto a low-melting-point metal foil using plating technology, or by using other well-known lamination or film formation technologies. The fuse element 2 may have a structure in which the entire surface of the low-melting-point metal layer 26 is covered by the high-melting-point metal layer 27, or it may have a structure in which it is covered except for a pair of opposing sides. The fuse element 2 may be configured with the high-melting-point metal layer 27 as the inner layer and the low-melting-point metal layer 26 as the outer layer, or it may be a multilayer structure of three or more layers in which the low-melting-point metal layer and the high-melting-point metal layer are alternately laminated, or it may be formed in various configurations such as providing an opening in a part of the outer layer to expose a part of the inner layer.

[0072] The fuse element 2 maintains its shape and does not melt even when the reflow temperature exceeds the melting temperature of the low-melting-point metal layer 26, by laminating a high-melting-point metal layer 27 as an outer layer onto a low-melting-point metal layer 26 as an inner layer. Therefore, the connection between the first and second electrode terminals 21, 22, the holding electrode 10, and the auxiliary electrode 15 and the fuse element 2 can be efficiently performed by reflow. Furthermore, fluctuations in the melting characteristics, such as failing to melt at a predetermined temperature or melting below a predetermined temperature due to localized high or low resistance values ​​caused by deformation of the fuse element 2 during reflow, can be prevented. Consequently, the protection element 1 can quickly melt the fuse element 2 in response to a predetermined overcurrent or heat generated by the heating element 5.

[0073] Furthermore, the fuse element 2 will not melt due to self-heating as long as a predetermined rated current is flowing through it. However, if a current higher than the rated value flows through it, it will melt due to self-heating (Joule heating), interrupting the current path between the first and second electrode terminals 21 and 22.

[0074] Furthermore, the fuse element 2 melts when the heating element 5 is energized and generates heat, interrupting the current path between the first and second electrode terminals 21 and 22. At this time, the molten low-melting-point metal layer 26 of the fuse element 2 erodes (solder erosion) the high-melting-point metal layer 27, causing the high-melting-point metal layer 27 to melt at a temperature lower than its melting point. Therefore, the fuse element 2 can be quickly interrupted by utilizing the erosive action of the low-melting-point metal layer 26 on the high-melting-point metal layer 27. In addition, since the fuse element 2 is interrupted by the physical pulling action of the holding electrode 10 and auxiliary electrode 15 on the molten conductor 2a, the current path between the first and second electrode terminals 21 and 22 can be interrupted quickly and reliably (Figures 5 and 9).

[0075] Furthermore, the fuse element 2 may be configured such that the volume of the low-melting-point metal layer 26 is greater than the volume of the high-melting-point metal layer 27. The fuse element 2 is heated by self-heating due to overcurrent or by the heat generated by the heating element 5, causing the low-melting-point metal to melt and corrode the high-melting-point metal, thereby enabling rapid melting and fuse-cutting. Therefore, by forming the fuse element 2 with a volume of low-melting-point metal layer 26 greater than the volume of high-melting-point metal layer 27, this corroding action is promoted, and the connection between the first and second electrode terminals 21 and 22 can be quickly interrupted.

[0076] Furthermore, in a fuse element 2 constructed by laminating a high-melting-point metal layer 27 onto an inner low-melting-point metal layer 26, the melting temperature can be significantly reduced compared to conventional chip fuses made of high-melting-point metals. Therefore, the fuse element 2 can have a larger cross-sectional area and a significantly improved current rating compared to chip fuses of the same size. In addition, it can be made smaller and thinner than conventional chip fuses with the same current rating and has excellent rapid melting properties.

[0077] Furthermore, the fuse element 2 can improve resistance to surges (pulse resistance) when an abnormally high voltage is instantaneously applied to the electrical system into which the protection element 1 is incorporated. In other words, the fuse element 2 must not melt even when a current of, for example, 100A flows for several milliseconds. In this regard, since large currents that flow for a very short time flow on the surface of the conductor (skin effect), the fuse element 2, which is provided with a high-melting-point metal layer 27 such as Ag plating with low resistance as an outer layer, can easily conduct the current applied by the surge and prevent melting due to self-heating. Therefore, the fuse element 2 can significantly improve resistance to surges compared to conventional fuses made of solder alloy.

[0078] Furthermore, flux (not shown) may be applied to the fuse element 2 to prevent oxidation and improve wettability during fuse blowing.

[0079] The first and second electrode terminals 21 and 22, which are connected to the ends of the fuse element 2, are conductive terminals and are provided both inside and outside the case 28 of the protective element 1. The first and second electrode terminals 21 and 22 have screw holes 20 at the ends that are led out to the outside of the case 28, and can be connected to connecting electrodes provided in an external circuit by screw fastening or the like.

[0080] Similarly, the third electrode terminal 23, which is connected to the external connection electrode 12a connected to the aforementioned heating element power supply electrode 12, is also provided both inside and outside the case 28 of the protective element 1, and a screw hole 20 is provided at the tip that is led out to the outside of the case 28.

[0081] [Circuit Configuration Example] Such a protective element 1 is used by being incorporated into a circuit in a lithium-ion secondary battery pack 40, for example, as shown in Figure 12. The battery pack 40 has a battery stack 45 consisting of a total of four lithium-ion secondary battery cells 41a to 41d.

[0082] The battery pack 40 includes a battery stack 45, a charge / discharge control circuit 46 that controls the charging and discharging of the battery stack 45, a protection element 1 to which the present invention is applied that shuts off the charge / discharge path when there is an abnormality in the battery stack 45, a detection circuit 47 that detects the voltage of each battery cell 41a to 41d, and a current control element 48 that acts as a switch element that controls the operation of the protection element 1 according to the detection result of the detection circuit 47.

[0083] The battery stack 45 consists of battery cells 41a to 41d connected in series, each requiring control to protect against overcharging and over-discharging. It is detachably connected to the charging device 42 via the positive terminal 40a and negative terminal 40b of the battery pack 40, and a charging voltage is applied from the charging device 42. The battery pack 40, once charged by the charging device 42, can power electronic devices by connecting the positive terminal 40a and negative terminal 40b to these devices.

[0084] The charge / discharge control circuit 46 comprises two current control elements 43a and 43b connected in series in the current path between the battery stack 45 and the charging device 42, and a control unit 44 that controls the operation of these current control elements 43a and 43b. The current control elements 43a and 43b are composed of, for example, field-effect transistors (hereinafter referred to as FETs), and the control unit 44 controls the conduction and interruption of the current path of the battery stack 45 in the charging direction and / or the discharge direction by controlling the gate voltage. The control unit 44 operates by receiving power from the charging device 42, and controls the operation of the current control elements 43a and 43b to interrupt the current path when the battery stack 45 is over-discharged or overcharged, according to the detection result by the detection circuit 47.

[0085] The protection element 1 is connected, for example, to the charge / discharge current path between the battery stack 45 and the charge / discharge control circuit 46, and its operation is controlled by the current control element 48.

[0086] The detection circuit 47 is connected to each battery cell 41a to 41d and detects the voltage value of each battery cell 41a to 41d, supplying each voltage value to the control unit 44 of the charge / discharge control circuit 46. The detection circuit 47 also outputs a control signal to control the current control element 48 when any one of the battery cells 41a to 41d reaches an overcharge voltage or over-discharge voltage.

[0087] The current control element 48 is composed of, for example, an FET, and when the voltage value of the battery cells 41a to 41d exceeds a predetermined over-discharge or overcharge state based on the detection signal output from the detection circuit 47, it activates the protection element 1 to control the charging and discharging current path of the battery stack 45 to be interrupted regardless of the switching operation of the current control elements 43a and 43b.

[0088] The protective element 1 to which the present invention is applied, used in the battery pack 40 having the above configuration, has the circuit configuration shown in Figure 9. Specifically, the protective element 1 has a first electrode terminal 21 connected to the battery stack 45 side and a second electrode terminal 22 connected to the positive electrode terminal 40a side, thereby connecting the fuse element 2 in series on the charge / discharge path of the battery stack 45. In addition, the protective element 1 has a heating element 5 connected to a current control element 48 via a heating element power supply electrode 12 and a third electrode terminal 23, and the heating element 5 is connected to an open end of the battery stack 45. As a result, one end of the heating element 5 is connected to the fuse element 2 and one open end of the battery stack 45 via a heating element lead electrode 7 and a holding electrode 10, and the other end is connected to the current control element 48 and the other open end of the battery stack 45 via a third electrode terminal 23. This forms a power supply path to the heating element 5, whose energization is controlled by the current control element 48.

[0089] [Operation of protective element] The heating element 5 is connected to a current control element 48 formed on the external circuit via a third electrode terminal 23, as the protection element 1 is mounted on the external circuit board. Under normal conditions, the heating element 5 is restricted from energizing and generating heat. When the detection circuit 47 detects an abnormal voltage in any of the battery cells 41a to 41d, it outputs a cutoff signal to the current control element 48. The current control element 48 then controls the current to energize the heating element 5. The heating element 5 starts generating heat as current flows from the battery stack 45.

[0090] The heat from the heating element 5 is transferred to the fuse element 2 via the heating element lead electrode 7, the through hole 11, and the holding electrode 10. It is also transferred from the insulating substrate 4 to the fuse element 2 via the holding electrode 10 and the auxiliary electrode 15, causing the fuse element 2 to melt. The molten conductor 2a of the fuse element 2 condenses on the holding electrode 10, the auxiliary electrode 15, and the heating element lead electrode 7, causing it to melt and break between the holding electrode 10 and the auxiliary electrode 15 (Figures 5, 6, and 10).

[0091] Furthermore, the protective element 1 is formed by incorporating a high-melting-point metal and a low-melting-point metal into the fuse element 2. This allows the low-melting-point metal to melt before the high-melting-point metal, and the fuse element 2 can be melted in a short time by utilizing the corrosive action of the molten low-melting-point metal on the high-melting-point metal.

[0092] When fuse element 2 melts, the charge and discharge path of the battery stack 45 is interrupted between the first and second electrode terminals 21 and 22. Also, when fuse element 2 melts, the heating element 5's power supply path is interrupted, and thus it stops generating heat.

[0093] Here, the protective element 1 has a fixing member 8 on the inner surface of the case 28, and this fixing member 8 contacts the cutting member 3 to suppress the oscillation of the cutting member 3. As a result, even if the connecting solder 9 softens due to the heat generated by the heating element 5 when the fuse element 2 is blown and the fixing state of the cutting member 3 to the fuse element 2 becomes unstable, the tilting of the insulating substrate 4 can be suppressed, and the fuse element 2 can be blown safely and quickly without the holding electrode 10 separating from the fuse element 2.

[0094] Furthermore, even if an overcurrent exceeding the rated value is passed through the fuse element 2, the protection element 1 can shut off the charge and discharge path of the battery pack 40 by melting the fuse element 2 due to self-heating.

[0095] The protective element 1 according to the present invention is not limited to use in lithium-ion secondary battery packs, but can of course be applied to various other applications that require interruption of the current path by an electrical signal.

[0096] [Example 1] Next, a modified example of the fixing member 8 will be described. In the following description, the same reference numerals are used for members identical to the protective element 1 described above, and their details may be omitted. As shown in Figures 13 to 15, the protective element 50 has multiple columnar members 17 formed on the inner surfaces of the upper case 29 and the lower case 30. The protective element 50 has four columnar members 17 on the top surface of the upper case 29, which are erected so as to abut the four corners of the rectangularly formed insulating substrate 4. Similarly, the protective element 50 also has four columnar members 17 on the bottom surface of the lower case 30, which are erected so as to abut the four corners of the rectangularly formed insulating substrate 4.

[0097] Figure 13 shows the upper case 29 and lower case 30 of the protective element 50, where (A) is a plan view of the upper case 29, (B) is a plan view of the lower case 30, (C) is an H-H' cross-sectional view of the upper case 29 shown in (A), and (D) is an I-I' cross-sectional view of the lower case 30 shown in (B).

[0098] With the protective element 50, the four corners of the insulating substrate 4 are supported by the columnar members 17, so that the swinging of the cutting member 3 can be suppressed at any angle. From the viewpoint of making the mounting positions of the cutting members 3 connected to both sides of the fuse element 2 symmetrical, it is preferable that the columnar members 17 of the upper case 29 and the lower case 30 are formed in positions facing each other. In addition, the above-mentioned intermediate material may be provided on the contact surface of each columnar member 17 with the cutting member 3.

[0099] [Differentiation 2] Next, another modified example of the fixing member 8 will be described. In the following description, the same reference numerals will be used for members identical to the protective element 1 described above, and their details may be omitted. The protective element 60 shown in Figure 16 is provided with a base portion 61 formed on the inner surface side of the case 28 and a fixing member 8 having a plurality of protrusions 62 that project from the base portion 61 toward the insulating substrate 4 side of the cutting member 3 and come into contact with the cutting member 3.

[0100] Figure 16 shows the upper case 29 and lower case 30 of the protective element 60, where (A) is a plan view of the upper case 29, (B) is a plan view of the lower case 30, (C) is a J-J' cross-sectional view of the upper case 29 shown in (A), and (D) is a K-K' cross-sectional view of the lower case 30 shown in (B).

[0101] The base portion 61 is roughly rectangular in shape and is provided on the top surface of the upper case 29 and the bottom surface of the lower case 30. In the protective element 60 shown in Figure 16, the base portion 61 is provided across opposing sides of the upper case 29 and across opposing sides of the lower case 30. This allows for precise positioning of the protrusion 62 provided on the base portion 61.

[0102] Multiple protrusions 62, each made of a columnar member, are formed protruding from each base portion 61. Each protrusion 62 may be formed integrally with the base portion 61, or it may be connected to the base portion 61 by adhesive or the like.

[0103] Furthermore, the protrusions 62 are erected so as to abut against predetermined positions on the cutting member 3. In the protective element 60 shown in Figure 16, four protrusions 62 are erected on each of the upper and lower cases 29 and 30 so as to abut against the four corners of the rectangularly formed insulating substrate 4. The tips of the protrusions 62 may be in contact with the cutting member 3, or they may be positioned close to the cutting member 3 so as to abut when the cutting member 3 swings. The size of the contact surface of the protrusions 62 with the cutting member 3 is set according to the contact position of the cutting member 3. The aforementioned intermediate material may be provided on the contact surface of the protrusions 62 with the cutting member 3.

[0104] The protective element 60 may also have protrusions 62 arranged along the side edge of the insulating substrate 4. In the protective element 60 shown in Figure 17, four base portions 61 are arranged in parallel at positions facing the cutting member 3 on the top surface of the upper case 29 and the bottom surface of the lower case 30, and the protrusions 62 are arranged along the side edge of the insulating substrate 4 where the heating element power supply electrode 12 and heating element electrode 14 are formed.

[0105] Figure 17 shows the upper case 29 and lower case 30 of the protective element 60, where (A) is a plan view of the upper case 29, (B) is a plan view of the lower case 30, (C) is an L-L' cross-sectional view of the upper case 29 shown in (A), and (D) is an M-M' cross-sectional view of the lower case 30 shown in (B).

[0106] Furthermore, in a plan view, the protective element 60 may have a plurality of protrusions 62 evenly arranged on the surface of the base 61. In the protective element 60 shown in Figure 18, the plurality of protrusions 62 facing the insulating substrate 4 of the cutting member 3 are provided close to the cutting member 3 and come into contact with it when the cutting member 3 swings. The area of ​​the plurality of protrusions 62 facing the cutting member 3 is set according to the cutting member 3, but it is preferable to cover the entire surface of the insulating substrate 4. The swing can be suppressed by the cutting member 3 coming into contact with one or more of the protrusions 62. In addition, the swing can be suppressed by the multiple protrusions 62 coming into contact with the cutting member 3, thereby stabilizing the cutting member 3.

[0107] Figure 18 shows the upper case 29 and lower case 30 of the protective element 60, where (A) is a plan view of the upper case 29, (B) is a plan view of the lower case 30, (C) is an N-N' cross-sectional view of the upper case 29 shown in (A), and (D) is an O-O' cross-sectional view of the lower case 30 shown in (B).

[0108] [Difference 3] Next, another modified example of the fixing member 8 will be described. In the following description, the same reference numerals will be used for members identical to the protective element 1 described above, and their details may be omitted. The protective element 70 shown in Figure 19 is provided with a conical member 71 as the fixing member 8. The conical member 71 suppresses oscillation by making point contact with the cutting member 3. By using the conical member 71, even if a sufficient contact area between the cutting member 3 and the fixing member 8 cannot be secured, contact can be made by point contact.

[0109] Figure 19 shows the upper case 29 and lower case 30 of the protective element 70, where (A) is a plan view of the upper case 29, (B) is a plan view of the lower case 30, (C) is a P-P' cross-sectional view of the upper case 29 shown in (A), and (D) is a Q-Q' cross-sectional view of the lower case 30 shown in (B).

[0110] Furthermore, one or more conical members 71 may be provided. Also, as described above, the position in which they are erected may be on the side edge opposite to the side edge on which the external connection electrode 12a of the insulating substrate 4 is formed, and in contact with the position facing the external connection electrode 12a, or they may be in contact with the four corners of the insulating substrate 4, or in contact along the side edge. In addition to the conical members 71, pyramidal members may also be used.

[0111] [Differentiation Example 4] Next, another modified example of the fixing member 8 will be described. In the following description, the same reference numerals will be used for the same components as those of the protective element 1 described above, and their details may be omitted. The protective element 80 shown in Figure 20 is provided with a block-shaped member 82 as the fixing member 8, which has a support surface 81 facing the main surface of the insulating substrate 4.

[0112] The block-shaped members 82 are provided on the top surface of the upper case 29 and the bottom surface of the lower case 30, respectively. As shown in Figures 21 and 22, the support surface 81 facing the insulating substrate 4 of the cutting member 3 is in contact with the heating element lead-out electrode 7 of the cutting member 3. The size of the support surface 81 is set according to the cutting member 3, but it is preferable that it has an area greater than or equal to the area of ​​the insulating substrate 4. The block-shaped members 82 can stably fix the cutting member 3 by the surface contact between the support surface 81 and the cutting member 3.

[0113] Furthermore, the block-shaped member 82 may be provided with its support surface 81 close to the cutting member 3 so that it contacts the cutting member 3 when it swings. By contacting the support surface 81 when the cutting member 3 swings, the block-shaped member 82 can restrict the swing so that it makes surface contact with the support surface 81. In addition, by having the support surface 81 and the cutting member 3 make surface contact, the block-shaped member 82 can stabilize the cutting member 3 even after it makes contact.

[0114] Figure 20 shows the upper case 29 and lower case 30 of the protective element 80, where (A) is a plan view of the upper case 29, (B) is a plan view of the lower case 30, (C) is an R-R' cross-sectional view of the upper case 29 shown in (A), and (D) is an S-S' cross-sectional view of the lower case 30 shown in (B).

[0115] The block-shaped member 82 is not limited to a rectangular parallelepiped cross-section; it can be formed in any shape, such as a trapezoid or cylindrical shape.

[0116] [Difference 5] Next, another modified example of the fixing member 8 will be described. In the following description, the same reference numerals will be used for members identical to the protective element 1 described above, and their details may be omitted. The protective element 90 shown in Figure 23 is provided with a canopy-shaped member 93 as the fixing member 8, which has an edge portion 91 that contacts the outer edge portion of the insulating substrate 4, and a recess 92 surrounded by the edge portion 91 that covers the main surface portion of the insulating substrate 4.

[0117] The canopy-shaped member 93 is provided on the top surface of the upper case 29 and the bottom surface of the lower case 30, respectively, and the edge portion 91 of the cutting member 3 facing the insulating substrate 4 is provided in contact with or close to the insulating substrate 4. The edge portion 91 may be formed continuously around the entire circumference where it contacts the insulating substrate 4, or it may be formed intermittently to avoid contact with electrodes, connecting solder, etc. The recess 92 is not limited to a dome shape, but can be formed in any shape such as a rectangular box shape or a cylindrical shape. The canopy-shaped member 93 can suppress the oscillation of the cutting member 3 by having the cutting member 3 contact the edge portion 91. In addition, the canopy-shaped member 93 ensures space above the heating element lead-out electrode 7 within the recess 92, so the aggregation of the molten conductor 2a is not hindered.

[0118] Figure 23 shows the upper case 29 and lower case 30 of the protective element 90, where (A) is a plan view of the upper case 29, (B) is a plan view of the lower case 30, (C) is a T-T' cross-sectional view of the upper case 29 shown in (A), and (D) is a U-U' cross-sectional view of the lower case 30 shown in (B).

[0119] [Modification 6] Next, another modified example of the fixing member 8 will be described. In the following description, the same reference numerals will be used for the same components as the protective element 1 described above, and their details may be omitted. The protective element 96 shown in Figures 24 to 26 is provided on the inner surface of the case 28 as the fixing member 8, and has a support piece 97 that supports the outer edge of the insulating substrate 4.

[0120] The support piece 97 is formed to protrude from the inner surface of the upper case 29 and the inner surface of the lower case 30, respectively, and is provided in contact with the surface 4a of the insulating substrate 4 opposite to the connection surface (back surface 4b) with the fuse element 2. The support piece 97 may be molded integrally with the upper and lower cases 29 and 30, or it may be formed as a separate component and attached to the upper and lower cases 29 and 30.

[0121] Furthermore, the area where the support piece 97 makes contact is preferably a position that does not hinder the aggregation of the molten conductor 2a, such as the corner of the surface 4a of the insulating substrate 4 or on the insulating layer 6. In particular, as shown in Figure 26, it is preferable that the support piece 97 be provided so as to contact the side edge of the insulating substrate 4 opposite to the side edge on which the heating element power supply electrode 12 is formed, and in a position facing the heating element power supply electrode 12. This effectively prevents the insulating substrate 4 from tilting toward the external connection electrode 12a. In addition, the support piece 97 can stably fix the cutting member 3 by making surface contact with the insulating substrate 4.

[0122] Furthermore, the support piece 97 may be provided in close proximity to the surface 4a of the insulating substrate 4 so as to contact the cutting member 3 when it swings. By contacting the insulating substrate 4 when the cutting member 3 swings, the support piece 97 can restrict the swing so that the insulating substrate 4 makes surface contact. In addition, by making surface contact with the insulating substrate 4, the support piece 97 can stabilize the insulating substrate 4 even after contact is made.

[0123] In addition, multiple support pieces 97 may be provided on the upper and lower cases 29 and 30, respectively, to support different side edges of the insulating substrate 4.

[0124] Figure 24 shows the upper case 29 and lower case 30 of the protective element 96, where (A) is a plan view of the upper case 29, (B) is a plan view of the lower case 30, (C) is a V-V' cross-sectional view of the upper case 29 shown in (A), and (D) is a W-W' cross-sectional view of the lower case 30 shown in (B).

[0125] In addition, while the protective elements described above all have the fusible members 3 connected to both sides of the fuse element 2, the protective element to which this technology is applied may have the fusible members 3 connected to only one side of the fuse element 2.

[0126] Furthermore, in all of the above-mentioned protective elements, the back surface 4b of the insulating substrate 4 is used as the connection surface to the fuse element 2, and the front surface 4a is used as the contact surface for the fixing member 8. However, in the protective element to which this technology is applied, the front surface 4a of the insulating substrate 4 may be used as the connection surface to the fuse element 2, and the back surface 4b may be used as the contact surface for the fixing member 8. In this case, the heating element lead electrode 7 is connected to the fuse element 2 by connecting solder 9. [Explanation of symbols]

[0127] 1 Protective element, 2 Fuse element, 2a Molten conductor, 3 Cutting member, 4 Insulating substrate, 4a Front surface, 4b Back surface, 5 Heating element, 6 Insulating layer, 7 Heating element lead electrode, 7a Tip, 7b Base, 8 Fixing member, 9 Connecting solder, 10 Holding electrode, 11 Through hole, 12 Heating element power supply electrode, 12a External connection electrode, 14 Heating element electrode, 15 Auxiliary electrode, 17 Columnar member, 21 First electrode terminal, 22 Second electrode terminal, 23 Third electrode terminal, 24 Conductive layer, 26 Low melting point metal layer, 27 High melting point metal layer, 28 Case, 29 Upper case, 30 Lower case, 30a Side edge, 30b Hollow part, 40 Battery pack, 41 Battery cell, 42 Charging device, 43 Current control element, 44 Control unit, 45 Battery stack, 46 Charge / discharge control circuit, 47 Detection circuit, 48 Current control element, 50 Protection element, 60 Protection element, 61 Base, 62 Protrusion, 70 Protection element, 71 Conical member, 80 Protection element, 81 Support surface, 82 Block-shaped member, 90 Protection element, 91 Edge, 92 Recess, 93 Canopy-shaped member, 96 Protection element, 97 Support piece

Claims

1. The case and, Fuse element and A cutting member connected to at least one side of the fuse element and for melting the fuse element, The above case has a fixing member provided on its inner surface, which contacts the cutting member to suppress the swinging of the cutting member, The above-mentioned fuse-cutting member comprises an insulating substrate and a heating element formed on the insulating substrate, and the insulating substrate is connected to the fuse element by a bonding material that softens due to the heat generated by the heating element. The above-mentioned fixing member has an intermediate material provided at the portion that comes into contact with the above-mentioned cutting member. Protective element.

2. The protective element according to claim 1, wherein the fixing member comprises one or more columnar members.

3. The protective element according to claim 1, wherein the fixing member has a base formed on the inner surface side of the case and a plurality of protrusions that project from the base toward the insulating substrate side of the cutting member.

4. The protective element according to claim 3, wherein the above-mentioned protrusions are evenly arranged on the base surface in a plan view.

5. The protective element according to claim 1, wherein the fixing member comprises one or more conical or pyramidal members.

6. The protective element according to claim 1, wherein the fixing member comprises an edge portion that contacts the outer edge portion of the insulating substrate and a canopy-shaped member that is surrounded by the edge portion and covers the main surface portion of the insulating substrate.

7. The protective element according to claim 1, wherein the fixing member is provided on the inner surface of the case and consists of a support piece that supports the outer edge of the insulating substrate.

8. The case and, Fuse element and A cutting member connected to at least one side of the fuse element and for melting the fuse element, The above case has a fixing member provided on its inner surface, which contacts the cutting member to suppress the swinging of the cutting member, The above-mentioned fuse-cutting member comprises an insulating substrate and a heating element formed on the insulating substrate, and the insulating substrate is connected to the fuse element by a bonding material that softens due to the heat generated by the heating element. The above-mentioned fixing member consists of a block-shaped member having a support surface facing the main surface portion of the insulating substrate. The support surface has an area equal to or greater than that of the insulating substrate. Protective element.

9. The protective element according to claim 8, wherein the fixing member is provided with an intermediate material in the portion that comes into contact with the cutting member.

10. The above-mentioned cutting member is connected to one side and the other side of the fuse element. The protective element according to any one of claims 1 to 9, wherein a plurality of fixing members are provided to suppress the oscillation of each of the fuse cutting members connected to one surface and the other surface of the fuse element.

11. The protective element according to claim 10, wherein the fuse-cutting member is connected to an opposing position via the fuse element.

12. The protective element according to any one of claims 1 to 11, wherein the fixing member is a separate member from the case and is fixed to the inner surface of the case.

13. The protective element according to any one of claims 1 to 11, wherein the fixing member is integrally molded with the case.

14. The protective element according to any one of claims 1 to 13, wherein the fixing member is provided in close proximity to the cutting member.

15. The protective element according to any one of claims 1 to 13, wherein the fixing member is provided in contact with the cutting member.

16. The system comprises one or more battery cells and a protective element connected to the charge / discharge path of the battery cells and blocking the charge / discharge path. The above-mentioned protective element is a battery pack that is the protective element described in any one of claims 1 to 15.

Images