Protection components and protection circuits

Abstract

A protection element comprises a first fuse element and a second fuse element connected in series. The protection element is configured such that when an overcurrent flows through the first fuse element and the second fuse element, the first fuse element is disconnected before the second fuse element.

Description

Technical Field

[0001] The present invention relates to a protection element and a protection circuit, and for example, to a protection element and a protection circuit connected between a secondary battery and a charger in a charge and discharge circuit of the secondary battery.

[0002] This application claims priority based on Tokugan Application No. 2018-220365 filed in Japan on November 26, 2018, the contents of which are cited here. Background Art

[0003] In the past, protection circuits were installed in various mobile devices equipped with secondary batteries, such as mobile phones and portable computers. As a mobile device equipped with a conventional protection circuit, there is, for example, a secondary battery device configured in the following manner: having a power storage device (secondary battery), a plurality of protection circuits, and a first and a second output terminal, wherein the protection circuits each have two fuse elements connected in series, and when an external circuit is connected to the first and the second output terminals, a discharge current supplied from the power storage device to the external circuit and a charge current supplied from the external circuit to the power storage device flow through the two fuse elements connected in series in the plurality of protection circuits (Patent Document 1).

[0004] The secondary battery device is configured as follows: a heater having one end connected to a connection point between fuse elements, the other end of each heater being connected to one end of a rectifier element, the other end of each rectifier element being connected to a switch element, and if the switch element is turned on, current flows to the heater of each protection circuit through the switch element and each rectifier element. In addition, in the secondary battery device, at least two rectifier elements are inserted in the current path connecting the terminals of the heaters of the protection circuits to each other, and even if a voltage difference is generated between the terminals of the heaters of the two protection circuits when a short-circuit current flows and a single fuse element is blown, at least one rectifier element will have a reverse bias. Therefore, current will not flow from the terminal of the heater of one protection circuit to the terminal of the heater of another protection circuit, and residual current caused by this will not be generated.

[0005] In addition, as a conventional protection element, the following protection element has been proposed: a plurality of fuse elements are arranged between a plurality of electrodes as input sources of an energized path, and the current is disconnected by the melting of the fuse elements caused by the heat of the energized heating element. In this protection element, when the specific energized path connected to a specific fuse element among the plurality of fuse elements is energized, other fuse elements are fused before the specific fuse element, and in this way, the fusing time of the plurality of fuse elements is controllable. Furthermore, the protection element is configured in the following manner: the specific electrode connected to the specific fuse element is an electrode that is an input source of an energized path that is definitely energized among the plurality of electrodes, and the distance from each of the plurality of fuse elements to the heating element is different in such a manner that the fusing time of the specific fuse element is longer than the fusing time of the other fuse elements (Patent Document 2).

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2004-193000

[0009] Patent Document 2: Japanese Patent Application Publication No. 2010-165685 Summary of the invention

[0010] Problems to be solved by the invention

[0011] However, in the protection circuit of the above-mentioned Patent Document 1, in order to prevent overcurrent as a whole system, multiple rectifying elements (diodes) corresponding to multiple heaters must be installed, and the device structure is complicated. In addition, there are problems such as poor manufacturability and high manufacturing cost.

[0012] Furthermore, the protection element of the above-mentioned patent document 2 is configured to be able to determine "the fuse element that will definitely blow last" within one protection element, so that at least when there is power flowing through the power path connected to the fuse element, all other fuse elements are blown first, thereby stopping only the heating of the heating resistor. There is no issue of preventing overcurrent and overvoltage in multiple protection circuits connected in parallel, and the prevention of overcurrent and overvoltage is not sufficient.

[0013] Furthermore, in recent years, mobile devices have been further advanced in terms of performance and functionality, and as the charge capacity of secondary batteries has further increased, a highly safe protection circuit that can reliably prevent overcurrent and overvoltage has been required.

[0014] An object of the present invention is to provide a protection element and a protection circuit which can reliably prevent overcurrent and overvoltage and improve safety with a simpler device configuration than before, and which can achieve good manufacturability and cost reduction.

[0015] Methods for solving problems

[0016] In order to achieve the above object, the present invention provides the following solutions.

[0017] [1] A protection element,

[0018] have:

[0019] A first fuse element and a second fuse element connected in series,

[0020] a heater connected between the first fuse element and the second fuse element,

[0021] a first electrode portion connected to the first fuse element on the opposite side of the second fuse element,

[0022] a second electrode portion connected to the second fuse element on the opposite side of the first fuse element, and

[0023] a third electrode portion connected between the first fuse element and the second fuse element and connected in series with the heater,

[0024] The protective circuit is configured such that when an overcurrent flows through the first fuse element and the second fuse element or when an overvoltage is applied to a secondary battery connected to the protective circuit, the first fuse element is disconnected earlier than the second fuse element.

[0025] [2] The protection element according to [1] above,

[0026] The first fuse element has thermal characteristics different from those of the second fuse element.

[0027] The thermal characteristics of the first fuse element and the thermal characteristics of the second fuse element include at least one of thermal resistance and thermal capacitance.

[0028] [3] The protection element according to [2] above,

[0029] The first fuse element and the second fuse element are fuse elements.

[0030] The length of the first fuse element is longer than that of the second fuse element, the cross-sectional area of ​​the first fuse element in the width direction is smaller than that of the second fuse element, and / or the thermal conductivity of the material forming the first fuse element is smaller than that of the material forming the second fuse element.

[0031] [4] The protection element according to any one of [1] to [3] above,

[0032] The first electrode portion has thermal characteristics different from those of the second electrode portion.

[0033] The thermal characteristics of the first electrode portion and the thermal characteristics of the second electrode portion include at least one of thermal resistance and thermal capacitance.

[0034] [5] According to the protection element described in [4] above, the thermal conductivity of the material forming the first electrode portion is smaller than the thermal conductivity of the material forming the second electrode portion.

[0035] [6] The protection element according to any one of [1] to [5] above,

[0036] Further having:

[0037] a first conductive portion for conducting the first electrode portion with an external circuit, and

[0038] a second conductive portion for connecting the second electrode portion to an external circuit,

[0039] The first conductive portion has thermal characteristics different from thermal characteristics of the second conductive portion.

[0040] The thermal characteristics of the first conductive portion and the thermal characteristics of the second conductive portion include at least one of thermal resistance and thermal capacitance.

[0041] [7] According to the protection element described in [6] above, the width-direction cross-sectional area of ​​the first conductive portion is smaller than the width-direction cross-sectional area of ​​the second conductive portion, and / or the thermal conductivity of the material forming the first conductive portion is smaller than the thermal conductivity of the material forming the second conductive portion.

[0042] [8] A protection circuit comprising a plurality of protection elements connected in parallel,

[0043] Each protection element constituting the plurality of protection elements has:

[0044] A first fuse element and a second fuse element connected in series,

[0045] a heater connected between the first fuse element and the second fuse element,

[0046] a first electrode portion connected to the first fuse element on the opposite side of the second fuse element,

[0047] a second electrode portion connected to the second fuse element on the opposite side of the first fuse element, and

[0048] a third electrode portion connected between the first fuse element and the second fuse element and connected in series with the heater,

[0049] The plurality of first fuse elements constituting the plurality of protection elements are connected to the same pole,

[0050] The circuit is configured such that when an overcurrent flows through the first fuse element and the second fuse element constituting the plurality of protection elements or an overvoltage is applied to a secondary battery connected to the protection circuit, the first fuse element in the protection element is disconnected earlier than the second fuse element.

[0051] [9] The protection circuit according to [8] above,

[0052] The first fuse element has thermal characteristics different from those of the second fuse element.

[0053] The thermal characteristics of the first fuse element and the thermal characteristics of the second fuse element include at least one of thermal resistance and thermal capacitance.

[0054]

[10] According to the protection circuit described in [9] above, the length of the first fuse element is longer than the length of the second fuse element, the cross-sectional area of ​​the first fuse element in the width direction is smaller than the cross-sectional area of ​​the second fuse element in the width direction, and / or the resistivity of the material forming the first fuse element is greater than the resistivity of the material forming the second fuse element.

[0055]

[11] The protection circuit according to any one of [8] to

[10] above,

[0056] The first electrode portion has thermal characteristics different from thermal characteristics of the second electrode portion.

[0057] The thermal characteristics of the first electrode portion and the thermal characteristics of the second electrode portion include at least one of thermal resistance and thermal capacitance.

[0058]

[12] In the protection circuit described in

[11] above, the thermal conductivity of the material forming the first electrode portion is smaller than the thermal conductivity of the material forming the first electrode portion.

[0059]

[13] The protection circuit according to any one of [8] to

[12] above,

[0060] Each protection element constituting the aforementioned plurality of protection elements further comprises:

[0061] a first conductive portion for conducting the first electrode portion with an external circuit, and

[0062] a second conductive portion for connecting the second electrode portion to an external circuit,

[0063] The first conductive portion has thermal characteristics different from thermal characteristics of the second conductive portion.

[0064] The thermal characteristics of the first conductive portion and the thermal characteristics of the second conductive portion include at least one of thermal resistance and thermal capacitance.

[0065]

[14] According to the protection circuit described in

[13] above, the width-direction cross-sectional area of ​​the first conductive portion is smaller than the width-direction cross-sectional area of ​​the second conductive portion, and / or the thermal conductivity of the material forming the first conductive portion is smaller than the thermal conductivity of the material forming the second conductive portion.

[0066]

[15] The protection circuit according to any one of [8] to

[14] above,

[0067] Further possesses:

[0068] a plurality of first connecting portions disposed between the plurality of first conducting portions and the external circuit, and a plurality of second connecting portions disposed between the plurality of second conducting portions and the external circuit,

[0069] The first connection portions connected to the first conductive portions of the plurality of protection elements have thermal characteristics different from thermal characteristics of the second connection portions connected to the second conductive portions of the protection elements.

[0070] The thermal characteristics of the first connection portion and the thermal characteristics of the second connection portion include at least one of thermal resistance and thermal capacitance.

[0071]

[16] According to the protection circuit described in

[15] above, the length of the aforementioned first connecting part is longer than the length of the aforementioned second connecting part, and / or the cross-sectional area of ​​the aforementioned first connecting part in the width direction is smaller than the cross-sectional area of ​​the aforementioned second connecting part in the width direction.

[0072] Effects of the Invention

[0073] According to the present invention, it is possible to reliably prevent overcurrent and overvoltage and improve safety with a simpler device configuration than before, and it is also possible to achieve good manufacturability and cost reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] [ Figure 1 ] Figure 1 This is a plan view schematically showing the structure of the protection element according to the first embodiment of the present invention.

[0075] [ Figure 2 ] Figure 2 for Figure 1 Cross-sectional view of the protection element at cutting line II-II.

[0076] [ Figure 3 ] Figure 3 This is a plan view schematically showing the structure of a protection element according to a second embodiment of the present invention.

[0077] [ Figure 4 ] Figure 4This is a plan view schematically showing the structure of a protection element according to a third embodiment of the present invention.

[0078] [ Figure 5 ] Figure 5 for Figure 4 Cross-sectional view of the protection element at the cutting line VV.

[0079] [ Figure 6 ] Figure 6 This is a plan view schematically showing the structure of a protection element according to a fourth embodiment of the present invention.

[0080] [ Figure 7 ] Figure 7 This is a plan view schematically showing the structure of a protection element according to a fifth embodiment of the present invention.

[0081] [ Figure 8 ] Figure 8 This is a plan view schematically showing the structure of a protection element according to a sixth embodiment of the present invention.

[0082] [ Fig. 9 ] Fig. 9 for Figure 8 Cross-sectional view of the protection element at the cutting line IX-IX.

[0083] [ Fig.10 ] Fig.10 This is a plan view schematically showing the structure of a protection element according to the seventh embodiment of the present invention.

[0084] [ Fig.11 ] Fig.11 for Fig.10 Cross-sectional view of the protection element at the cutting line XI-XI.

[0085] [ Fig.12 ] Fig.12 This is a plan view schematically showing the structure of a protection circuit according to an eighth embodiment of the present invention.

[0086] [ Fig.13 ] Fig.13 For Fig.12 This circuit diagram explains the operation of the protection circuit, showing the state before the disconnection operation.

[0087] [ Fig.14 ] Fig.14 For Fig.12 This circuit diagram explains the operation of the protection circuit, showing the state after the disconnection operation. DETAILED DESCRIPTION

[0088] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0089] [Configuration of protection element]

[0090] Figure 1 This is a plan view schematically showing the structure of the protection element according to the first embodiment of the present invention. Figure 2 for Figure 1 Cross-sectional view of the protection element at cutting line II-II.

[0091] like Figure 1 and Figure 2 As shown, the protection element 10 includes a substrate 11, a first fuse element 12A and a second fuse element 13A connected in series on the substrate 11, a heater 14 connected between the first fuse element 12A and the second fuse element 13A, a first electrode portion 15A connected to the first fuse element 12A on the side opposite to the second fuse element 13A, a second electrode portion 16A connected to the second fuse element 13A on the side opposite to the first fuse element 12A, a third electrode portion 17 connected between the first fuse element 12A and the second fuse element 13A and connected in series with the heater 14, a first conduction portion 18A for conducting the first electrode portion 15A with an external circuit, and a second conduction portion 19A for conducting the second electrode portion 16A with an external circuit. Furthermore, the protection element 10 is configured in the following manner: when an overcurrent flows in the first fuse element 12A and the second fuse element 13A or when a secondary battery (refer to Fig.13 , Fig.14 ) is applied with an overvoltage, the first fuse element 12A is disconnected earlier than the second fuse element 13A. The configuration and operation when an overvoltage is applied to the secondary battery connected to the protection circuit are described below.

[0092] The substrate 11 is not particularly limited as long as it is a substrate of an insulating material. For example, in addition to substrates used in printed wiring boards such as ceramic substrates and glass epoxy substrates, glass substrates, resin substrates, insulating metal substrates, etc. can also be used. It should be noted that, among them, ceramic substrates are preferred as insulating substrates with excellent heat resistance and good thermal conductivity.

[0093] In the present embodiment, the first fuse element 12A and the second fuse element 13A are integrally formed, and are supported by the first electrode portion 15A, the second electrode portion 16A, and the third electrode portion 17 via three conductive support bodies 21 , 22 , and 23 .

[0094] The first fuse element 12A and the second fuse element 13A may be formed of different members. In addition, the first fuse element 12A and the second fuse element 13A are in the shape of a sheet, but the shape is not limited to this, and may be in the shape of a rod.

[0095] The first fuse element 12A has a thermal characteristic different from the thermal characteristic of the second fuse element 13A. The thermal characteristics of the first fuse element 12A and the thermal characteristics of the second fuse element 13A include at least one of thermal resistance and thermal capacitance. Thermal resistance (K / W) means the ease of heat transfer. The greater the thermal resistance, the more difficult it is to transfer heat (thermal resistance [K / W] = length [m] / {cross-sectional area [m 2 ]×thermal conductivity [W / (m·K)]}). In addition, heat capacity (J / K) means the amount of heat required to increase a unit temperature, that is, the ease with which the temperature changes. The greater the heat capacity, the more difficult it is to change the temperature. Therefore, it is preferred that, for example, (1) the thermal resistance of the first fuse element 12A is greater than the thermal resistance of the second fuse element 13A, (2) the heat capacity of the first fuse element 12A is smaller than the heat capacity of the second fuse element 13A, or (3) both of the above (1) and (2) are satisfied.

[0096] Specifically, the first fuse element 12A and the second fuse element 13A have, for example, a sheet shape. In the present embodiment, the length of the first fuse element 12A is longer than the length of the second fuse element 13A. In this case, the thermal resistance of the first fuse element 12A is greater than the thermal resistance of the second fuse element 13A, so when an overcurrent flows through the first fuse element 12A and the second fuse element 13A, the first fuse element 12A is disconnected earlier than the second fuse element 13A.

[0097] The materials constituting the first fuse element 12A and the second fuse element 13A can be various low melting point metals that have been used as fuse materials in the past. Examples of low melting point metals include SnSb alloys, BiSnPb alloys, BiPbSn alloys, BiPb alloys, BiSn alloys, SnPb alloys, SnAg alloys, PbIn alloys, ZnAl alloys, InSn alloys, and PbAgSn alloys. The materials constituting the first fuse element 12A and the second fuse element 13A are preferably the same, but may be different.

[0098] The heater 14 is disposed on the substrate 11 and directly below the third electrode portion 17. An insulating layer 24 is disposed between the heater 14 and the third electrode portion 17. One end of the heater 14 is connected to the heater lead electrode portion 14A, and the other end is connected to the third electrode portion 17 via the routing electrode portion 17A.

[0099] The heater 14 can be formed, for example, by applying a resistor paste containing a conductive material such as ruthenium oxide, carbon black, an inorganic binder such as water glass, or an organic binder such as a thermosetting resin, and firing the paste as needed. In addition, the heater 14 can be formed by forming a thin film of ruthenium oxide, carbon black, etc. through a printing, plating, vapor deposition, or sputtering process, or by pasting or laminating these films.

[0100] The first electrode portion 15A, the second electrode portion 16A, and the third electrode portion 17 are electrodes into which the melted first fuse element 12A or the second fuse element 13A flows. The materials constituting the first electrode portion 15A, the second electrode portion 16A, and the third electrode portion 17 are not particularly limited, and metals having good wettability with the first fuse element 12A or the second fuse element 13A in a molten state can be cited. For example, as the materials constituting the first electrode portion 15A, the second electrode portion 16A, and the third electrode portion 17, a metal single substance such as copper, at least a material formed of Ag, Ag-Pt, Ag-Pd, Au, etc. on the surface can be used. The first electrode portion 15A and the second electrode portion 16A are connected to the first connecting portion and the second connecting portion described later via the solder portions 25 and 26, respectively. In addition, the third electrode portion 17 is connected to the third connecting portion not shown in the figure via the solder portion 27. As materials constituting the heater lead electrode portion 14A and the detour electrode portion 17A, a material having a metal element such as copper and at least a surface formed of Ag, Ag-Pt, Ag-Pd, Au, etc. can be used, similarly to the first electrode portion 15A, the second electrode portion 16A, and the third electrode portion 17. In addition, the heater lead electrode portion 14A is connected to a switching element described later via a solder portion 27.

[0101] The first conductive portion 18A and the second conductive portion 19A are, for example, through holes, which are formed by filling the inner peripheral surface of the through hole formed in the substrate 11 with a conductor. As materials constituting the first conductive portion 18A and the second conductive portion 19A, silver, copper, tungsten, or alloys thereof can be cited. The first conductive portion 18A and the second conductive portion 19A can be any configuration as long as they can be connected to an external circuit, and can also be a configuration other than a through hole. In addition, the protection element 10 can also be a configuration without the first conductive portion 18A and the second conductive portion 19A.

[0102] Figure 3 This is a plan view schematically showing the structure of the protection element involved in the second embodiment of the present invention. In the protection element involved in the second embodiment, the structures of the first and second fuse elements are different. Otherwise, it is the same as the protection element involved in the first embodiment, so the description of the repeated parts is omitted, and the different parts are described below.

[0103] like Figure 3 As shown, in the second embodiment, the width of the first fuse element 12B may be smaller than the width of the second fuse element 13B. In this case, the cross-sectional area of ​​the first fuse element 12B in the width direction is smaller than the cross-sectional area of ​​the second fuse element 13B in the width direction, and the thermal resistance of the first fuse element 12B is greater than the thermal resistance of the second fuse element 13B. Therefore, when an overcurrent flows through the first fuse element 12B and the second fuse element 13B or an overvoltage is applied to the secondary battery connected to the protection circuit, the first fuse element 12B is disconnected earlier than the second fuse element 13B.

[0104] The length of the first fuse element 12B is the same as the length of the second fuse element 13B, but this is not the only case, and the length of the first fuse element 12B may be longer than the length of the second fuse element 13B. Thus, the thermal resistance of the first fuse element 12B can be made greater than that of the second fuse element 13B.

[0105] Figure 4 This is a plan view schematically showing the structure of a protection element according to a third embodiment of the present invention. Figure 5 for Figure 4 The protection element according to the third embodiment is the same as the protection element according to the first embodiment except that the configurations of the first and second fuse elements are different.

[0106] like Figure 4 and Figure 5 As shown, in the third embodiment, the thickness of the first fuse element 12C can be smaller than the thickness of the second fuse element 13C. The thickness of the first fuse element 12C is, for example, 0.1 mm, and the thickness of the second fuse element 13C is, for example, 0.2 mm. In this configuration, the cross-sectional area of ​​the first fuse element 12C in the width direction is smaller than the cross-sectional area of ​​the second fuse element 13C in the width direction, and the thermal resistance of the first fuse element 12C is greater than the thermal resistance of the second fuse element 13C. Therefore, when an overcurrent flows through the first fuse element 12C and the second fuse element 13C or an overvoltage is applied to the secondary battery connected to the protection circuit, the first fuse element 12C is disconnected earlier than the second fuse element 13C.

[0107] The length of the first fuse element 12C is the same as the length of the second fuse element 13C, but this is not limited to this case. The length of the first fuse element 12C may be longer than the length of the second fuse element 13C. In addition, the width of the first fuse element 12C is the same as the width of the second fuse element 13C, but this is not limited to this case. The width of the first fuse element 12C may be smaller than the width of the second fuse element 13C. Thus, the thermal resistance of the first fuse element 12C can be further increased than the thermal resistance of the second fuse element 13C.

[0108] Figure 6 This is a plan view schematically showing the structure of a protection element according to a fourth embodiment of the present invention. The protection element according to the fourth embodiment is the same as the protection element according to the first embodiment except that the structures of the first and second fuse elements are different.

[0109] like Figure 6As shown, in the fourth embodiment, the first fuse element 12D has a plurality of fuse elements 12d of the same shape, and the second fuse element 13D has a plurality of fuse elements 13d of the same shape. Furthermore, the number of fuse elements constituting the first fuse element 12D may be less than the number of fuse elements constituting the second fuse element 13D. In this configuration as well, the sum of the cross-sectional areas in the width direction of the plurality of fuse elements 12d is smaller than the sum of the cross-sectional areas in the width direction of the plurality of fuse elements 13d, and the thermal resistance of the first fuse element 12D is greater than the thermal resistance of the second fuse element 13D. Therefore, when an overcurrent flows through the first fuse element 12D and the second fuse element 13D or an overvoltage is applied to the secondary battery connected to the protection circuit, the first fuse element 12D is disconnected earlier than the second fuse element 13D.

[0110] The length of the first fuse element 12D is the same as the length of the second fuse element 13D, but this is not limited to this case. The length of the first fuse element 12D may be longer than the length of the second fuse element 13D. In addition, the width of the fuse element 12d constituting the first fuse element 12D is the same as the width of the fuse element 13d constituting the second fuse element 13D, but this is not limited to this case. The width of the fuse element 12d may be smaller than the width of the fuse element 13d. Furthermore, the thickness of the first fuse element 12D may be smaller than the thickness of the second fuse element 13D. Thus, the thermal resistance of the first fuse element 12D can be further made greater than the thermal resistance of the second fuse element 13D.

[0111] Figure 7 This is a plan view schematically showing the structure of a protection element according to a fifth embodiment of the present invention. The protection element according to the fifth embodiment is the same as the protection element according to the first embodiment except that the structures of the first and second fuse elements are different.

[0112] like Figure 7 As shown, in the fifth embodiment, the thermal conductivity of the material forming the first fuse element 12E can be smaller than the thermal conductivity of the material forming the second fuse element 13E. In this configuration as well, the thermal resistance of the first fuse element 12E is greater than the thermal resistance of the second fuse element 13E, and therefore, when an overcurrent flows through the first fuse element 12E and the second fuse element 13E or an overvoltage is applied to the secondary battery connected to the protection circuit, the first fuse element 12E is disconnected earlier than the second fuse element 13E.

[0113] The length of the first fuse element 12E is the same as the length of the second fuse element 13E, but this is not limited to this case. The length of the first fuse element 12E may be longer than the length of the second fuse element 13E. In addition, the width of the first fuse element 12E is the same as the width of the second fuse element 13E, but this is not limited to this case. The width of the first fuse element 12E may be smaller than the width of the second fuse element 13E. Furthermore, the thickness of the first fuse element 12E may be smaller than the thickness of the second fuse element 13E. Thus, the thermal resistance of the first fuse element 12E can be further increased than the thermal resistance of the second fuse element 13E.

[0114] In this way, it is preferred that the first fuse elements 12A to 12E and the second fuse elements 13A to 13E are fuse elements, and the length of the first fuse element 12A is longer than the length of the second fuse element 13A, the cross-sectional area of ​​the first fuse element 12B (12C, 12D) is smaller than the cross-sectional area of ​​the second fuse element 13B (13C, 13D), and / or the thermal conductivity of the material forming the first fuse element 12E is smaller than the thermal conductivity of the material forming the second fuse element 13E. Thus, when overcurrent flows through the first fuse element 12A (12B, 12C, 12D, 12E) and the second fuse element 13A (13B, 13C, 13D, 13E) or when overvoltage is applied to the secondary battery connected to the protection circuit, the first fuse element 12A (12B, 12C, 12D, 12E) is effectively disconnected before the second fuse element 13A (13B, 13C, 13D, 13E), thereby further improving safety with an extremely simple structure.

[0115] Figure 8 This is a plan view schematically showing the structure of a protection element according to a sixth embodiment of the present invention. Fig. 9 for Figure 8 The protection element according to the sixth embodiment is the same as the protection element according to the first embodiment except that the configurations of the first and second electrode portions are different.

[0116] like Figure 8 and Fig. 9As shown, in the sixth embodiment, the first electrode portion 15B has thermal characteristics different from those of the second electrode portion 16B, and the thermal characteristics of the first electrode portion 15B and the thermal characteristics of the second electrode portion 16B may include at least one of thermal resistance and thermal capacitance. For example, preferably (1) the thermal resistance of the first electrode portion 15B is greater than the thermal resistance of the second electrode portion 16B, (2) the thermal capacitance of the first electrode portion 15B is smaller than the thermal capacitance of the second electrode portion 16B, or (3) both of the above (1) to (2) are satisfied. The meaning of the thermal characteristics of the first electrode portion 15B and the second electrode portion 16B is the same as the meaning of the thermal characteristics of the first and second fuse elements described in the first embodiment.

[0117] In this embodiment, the thermal conductivity of the material forming the first electrode portion 15B is smaller than the thermal conductivity of the material forming the second electrode portion 16B. In this case, the thermal resistance of the first electrode portion 15B is greater than the thermal resistance of the second electrode portion 16B. Therefore, when an overcurrent flows through the first fuse element 12A and the second fuse element 13A, the first fuse element 12A is disconnected earlier than the second fuse element 13A, and the safety can be further improved with an extremely simple structure.

[0118] Fig.10 This is a plan view schematically showing the structure of a protection element according to a seventh embodiment of the present invention. Fig.11 for Fig.10 The protection element according to the seventh embodiment is the same as the protection element according to the first embodiment except that the configurations of the first and second conductive portions are different.

[0119] like Fig.10 and Fig.11 As shown, in the sixth embodiment, the first conductive portion 18B has a thermal characteristic different from the thermal characteristic of the second conductive portion 19B, and the thermal characteristic of the first conductive portion 18B and the thermal characteristic of the second conductive portion 19B may include at least one of thermal resistance and thermal capacitance. For example, it is preferred that (1) the thermal resistance of the first conductive portion 18B is greater than the thermal resistance of the second conductive portion 19B, (2) the thermal capacitance of the first conductive portion 18B is smaller than the thermal capacitance of the second conductive portion 19B, or (3) both of the above (1) and (2) are satisfied. The meaning of the thermal characteristics of the first conductive portion 18B and the second conductive portion 19B is the same as the meaning of the thermal characteristics of the first and second fuse elements described in the first embodiment.

[0120] In this embodiment, the width of the first conductive portion 18B is smaller than the width of the second conductive portion 19B. In this case, the cross-sectional area in the width direction of the first conductive portion 18B is smaller than the cross-sectional area in the width direction of the second conductive portion 19B, and the thermal resistance of the first conductive portion 18B is greater than the thermal resistance of the second conductive portion 19A. Therefore, when an overcurrent flows through the first fuse element 12A and the second fuse element 13A, the first fuse element 12A is disconnected earlier than the second fuse element 13A.

[0121] In addition, the thermal conductivity of the material forming the first conductive portion 18B may be smaller than the thermal conductivity of the material forming the second conductive portion 19B. Thus, the thermal resistance of the first conductive portion 18B can be further increased than the thermal resistance of the second conductive portion 19B. When the thermal conductivity of the material forming the first conductive portion 18B is smaller than the thermal conductivity of the material forming the second conductive portion 19B, the width of the first conductive portion 18B is preferably smaller than the width of the second conductive portion 19B, or may be the same as the width of the second conductive portion 19B.

[0122] In this way, by making the width-direction cross-sectional area of ​​the first conductive portion 18B smaller than the width-direction cross-sectional area of ​​the second conductive portion 19B, and / or the thermal conductivity of the material forming the first conductive portion 18B is smaller than the thermal conductivity of the material forming the second conductive portion 19B, when an overcurrent flows through the first fuse element 12A and the second fuse element 13A, the first fuse element 12A is effectively disconnected before the second fuse element 13A, and safety can be further improved using an extremely simple structure.

[0123] [Configuration of protection circuit]

[0124] Fig.12 This is a plan view schematically showing the configuration of a protection circuit according to an eighth embodiment of the present invention. In the eighth embodiment, a case where a protection circuit includes a plurality of protection elements 10 according to the first embodiment is described as an example.

[0125] like Fig.12 As shown, the protection circuit 1 further includes a plurality of protection elements 10, 10, 10 connected in parallel, a plurality of first connection portions 31, 31, 31 arranged between the plurality of first electrode portions 15A, 15A, 15A and the external circuit, and a plurality of second connection portions 32, 32, 32 arranged between the plurality of second electrode portions 16A, 16A, 16A and the external circuit.

[0126] The first connecting portions 31, 31, 31 are connected to the first electrode portions 15A, 15A, 15A via the plurality of solder portions 25, 25, 25, respectively. In addition, the second connecting portions 32, 32, 32 are connected to the second electrode portions 16A, 16A, 16A via the plurality of solder portions 26, 26, 26, respectively. The plurality of first connecting portions 31, 31, 31 and the plurality of second connecting portions 32, 32, 32 are, for example, circuit patterns mounted on a substrate. There is no particular limitation on the material constituting the plurality of first connecting portions 31, 31, 31 and the plurality of second connecting portions 32, 32, 32, and 32, and examples thereof include copper or a copper alloy.

[0127] The structure is as follows: a plurality of first fuse elements 12A, 12A, 12A constituting a plurality of protection elements 10, 10, 10 are connected to the same pole, and when an overcurrent flows through the first fuse elements 12A and the second fuse elements 13A constituting the plurality of protection elements 10, 10, 10, the first fuse element 12A in the protection element is disconnected before the second fuse element 13A.

[0128] In addition, in the present embodiment, the first connection portion 31 connected to the first fuse element 12A constituting the plurality of protection elements 10, 10, 10 respectively has a thermal characteristic different from the thermal characteristic of the second connection portion 32 connected to the second fuse element 13A of the protection element 10. Moreover, it is preferred that the thermal characteristic of the first connection portion 31 and the thermal characteristic of the second connection portion 32 include at least one of thermal resistance and thermal capacity. For example, it is preferred that (1) the thermal resistance of the first connection portion 31 is greater than the thermal resistance of the second connection portion 32, (2) the thermal capacity of the first connection portion 31 is smaller than the thermal capacity of the second connection portion 32, or (3) both of the above (1) to (2) are satisfied. The meaning of the thermal characteristics of the first connection portion 31 and the second connection portion 32 is the same as the meaning of the thermal characteristics of the first and second fuse elements described in the above first embodiment.

[0129] In the present embodiment, the widths of the plurality of first connection portions 31, 31, 31 are smaller than the widths of the plurality of second connection portions 32, 32, 32. In this case, the cross-sectional area in the width direction of the first connection portion 31 is smaller than the cross-sectional area in the width direction of the second connection portion 32, and the thermal resistance of the first connection portion 31 is larger than the thermal resistance of the second connection portion 32. Therefore, when an overcurrent flows through the first fuse element 12A and the second fuse element 13A or an overvoltage is applied to the secondary battery connected to the protection circuit, the first fuse element 12A is disconnected earlier than the second fuse element 13A.

[0130] In addition, as described above, the first connection portion 31 is connected to the first electrode portion 15A via the solder portion 25 and the through hole and the through hole. The shape and material of the solder portion 25 may affect the thermal characteristics of the first connection portion 31. Therefore, the thermal characteristics of the first connection portion 31 may include the thermal characteristics of the bonding member such as the solder portion 25. Similarly, the thermal characteristics of the second connection portion 32 may include the thermal characteristics of the bonding member such as the solder portion 26. The meaning of the thermal characteristics of the bonding member is the same as the meaning of the thermal characteristics of the first and second fuse elements described in the first embodiment.

[0131] Fig.13 and Fig.14 For Fig.12 The circuit diagram for explaining the operation of the protection circuit 1 is as follows, Fig.13 The status before disconnection is displayed. Fig.14 The status after disconnection is displayed.

[0132] In the protection circuit 1, if Fig.13 As shown, for example, a plurality of first connection parts 31, 31, 31 are connected to the parallel connection point A via an external circuit, and are connected to the positive electrodes of the secondary batteries 33, 33. In addition, a plurality of second connection parts 32, 32, 32 are connected to the parallel connection point B via an external circuit, and are connected to the positive electrode of the charger 34. The heater 14 connected to the third electrode part 17 is connected to both, for example, the negative electrodes of the secondary batteries 33, 33 and the negative electrode of the charger 34. A switching element 35 such as FET is provided on the downstream side of the plurality of third electrode parts 17. That is, the heater 14 located on the downstream side of the plurality of third electrode parts is connected to the switching element 35 via the heater lead-out electrode part 14A at one end, and is connected to the first fuse element 12A and the second fuse element 13A via the bypass electrode part 17A and the third electrode part 17 at the other end.

[0133] When the secondary batteries 33 and 33 are charged, power is supplied from the charger 34 via the external circuit to the secondary batteries 33 and 33. When the secondary batteries are discharged, power is supplied from the secondary batteries 33 and 33 to the external circuit. In this way, the same power is supplied to both the first fuse element 12A and the second fuse element 13A when the secondary batteries 33 and 33 are charged and discharged.

[0134] When the secondary batteries 33, 33 are charged or discharged, if an overcurrent or overvoltage occurs for some reason, since the thermal resistance of the first connection portion 31 is greater than the thermal resistance of the second connection portion 32, Fig.14As shown, the first fuse element 12A is disconnected before the second fuse element 13A. Since the first fuse element 12A is disconnected before the second fuse element 13A among all the protection elements 10, 10, 10, the circuit on the secondary battery 33 side is separated from the circuit on the charger 34 side. As a result, the current does not flow back through the heater 14, and it is not necessary to provide a rectifying element such as a diode between the plurality of protection elements 10, 10, 10 and the switch element 35.

[0135] In the present embodiment, the lengths of the plurality of first connection parts 31, 31, 31 are the same as the lengths of the plurality of second connection parts 32, 32, 32, but this is not limited to the case, and the lengths of the plurality of first connection parts 31, 31, 31 may be different from the lengths of the plurality of second connection parts 32, 32, 32. Thus, the thermal resistance of the first connection part 31 can be further made greater than the thermal resistance of the second connection part 32.

[0136] In addition, in the present embodiment, the widths of the plurality of first connecting parts 31, 31, 31 are different from the widths of the plurality of second connecting parts 32, 32, 32, but this is not limited to this case. When the widths of the plurality of first connecting parts 31, 31, 31 are the same as the widths of the plurality of second connecting parts 32, 32, 32, 32, the lengths of the plurality of first connecting parts 31, 31, 31 may also be different from the lengths of the plurality of second connecting parts 32, 32, 32.

[0137] In addition, the protection circuit 1 may also include a detection element (not shown) connected to each of the secondary batteries 33, 33 and to the switch element 35. The detection element always monitors whether a high voltage state, particularly an overvoltage, is formed, and outputs a control signal to the switch element 35 when a high voltage state is formed. In this case, the switch element 35 allows the current from the secondary battery 33 to flow through the heater 14 according to the control signal, thereby causing the heater 14 to heat up. As a result, the first fuse element 12A is blown before the second fuse element 13A.

[0138] In this way, by making the length of the first connecting portion 31 longer than the length of the second connecting portion 32, and / or the cross-sectional area of ​​the first connecting portion 31 in the width direction smaller than the cross-sectional area of ​​the second connecting portion 32 in the width direction, when an overcurrent flows through the first fuse element 12A and the second fuse element 13A or when an overvoltage is applied to the secondary battery 33 connected to the protection circuit 1, the first fuse element 12A is effectively disconnected before the second fuse element 13A, and safety can be further improved using an extremely simple structure.

[0139] In this embodiment, the protection circuit 1 includes the protection element 10 of the first embodiment, but the present invention is not limited to this case and may include the protection elements of the second to seventh embodiments. In this case, the thermal resistance of the first fuse element provided in each protection element may be greater than the thermal resistance of the second fuse element.

[0140] Furthermore, in the present embodiment, in the protection circuit 1, the thermal characteristics of the first connection portion 31 and the thermal characteristics of the second connection portion 32 are different, but the present invention is not limited to this case. When the protection element 10 has the configuration of the first to seventh embodiments, the thermal characteristics of the first connection portion 31 and the thermal characteristics of the second connection portion 32 may be the same. For example, the cross-sectional areas in the width direction of the plurality of first connection portions 31, 31, 31 may be the same as the cross-sectional areas in the width direction of the plurality of second connection portions 32, 32, 32, and further, the thermal conductivity of the plurality of first connection portions 31, 31, 31 and the thermal conductivity of the plurality of second connection portions 32, 32, 32 may be the same.

[0141] As described above, according to the above embodiment, when an overcurrent flows through the first fuse element 12A (12B, 12C, 12D, 12E) and the second fuse element 13A (13B, 13C, 13D, 13E) or when an overvoltage is applied to the secondary battery 33 connected to the protection circuit 1, the first fuse element 12A (12B, 12C, 12D, 12E) is disconnected earlier than the second fuse element 13A (13B, 13C, 13D, 13E), so that the first fuse element 12A (12B, 12C, 12D, 12E) can be used to disconnect the circuit on one side of the first fuse element 12A (12B, 12C, 12D, 12E) and the circuit on the other side. Therefore, when forming a protection circuit having a plurality of protection elements 10 connected in parallel, by connecting a plurality of first fuse elements 12A (12B, 12C, 12D, 12E) constituting the plurality of protection elements 10 to the same pole, overcurrent and overvoltage can be effectively prevented without providing a rectifying element such as a diode. Therefore, the protection element 10 can effectively prevent overcurrent and overvoltage and improve safety with a simpler structure than before, and good manufacturability and cost reduction can be achieved.

[0142] Furthermore, according to the above-described embodiment, in the protection circuit having the plurality of protection elements 10 connected in parallel, the plurality of first fuse elements 12A constituting the plurality of protection elements 10 are connected to the same pole so that when an overcurrent flows through the first fuse elements 12A (12B, 12C, 12D, 12E) and the second fuse elements 13A (13B, 13C, 13D, 13E) constituting the plurality of protection elements 10, or when an overvoltage is applied to the secondary battery 33 connected to the protection circuit 1, The first fuse element 12A (12B, 12C, 12D, 12E) in the protection element is configured to be disconnected earlier than the second fuse element 13A (13B, 13C, 13D, 13E), so that the first fuse element 12A (12B, 12C, 12D, 12E) can be used to disconnect the circuit on one side (e.g., the secondary battery side circuit) and the circuit on the other side (e.g., the charger side circuit) of the first fuse element 12A (12B, 12C, 12D, 12E). Therefore, overcurrent and overvoltage can be effectively prevented without providing a plurality of rectifying elements such as diodes. Therefore, the protection circuit 1 can effectively prevent overcurrent and overvoltage and improve safety with a simpler configuration than before, and can achieve good manufacturability and cost reduction.

[0143] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims.

[0144] For example, in the above-mentioned embodiment, the thermal characteristics of the first and second fuse elements, the first and second electrode parts, the first and second conductive parts or the first and second connecting parts are different from each other, but it is not limited to this case. It is also possible that the conductor resistance values ​​(resistance (Ω)) of the first and second fuse elements, the first and second electrode parts, the first and second conductive parts and / or the first and second connecting parts are different from each other. Utilizing this structure, it is also possible to configure the first fuse element to be disconnected earlier than the second fuse element when an overcurrent flows through the first fuse element and the second fuse element or when an overvoltage is applied to the secondary battery connected to the protection circuit, thereby achieving the same effect as above.

[0145] Explanation of symbols

[0146] 1 Protection circuit

[0147] 10. Protection components

[0148] 11 base plate

[0149] 12A 1st fuse element

[0150] 12B 1st fuse element

[0151] 12C 1st fuse element

[0152] 12D 1st fuse element

[0153] 12d Fuse element

[0154] 12E 1st fuse element

[0155] 13A 2nd fuse element

[0156] 13B 2nd fuse element

[0157] 13C 2nd fuse element

[0158] 13D 2nd fuse element

[0159] 13d Fuse element

[0160] 13E 2nd fuse element

[0161] 14 Heater

[0162] 14A Heater lead electrode

[0163] 15A 1st electrode

[0164] 15B 1st electrode part

[0165] 16A Second electrode part

[0166] 16B Second electrode part

[0167] 17. Electrode section 3

[0168] 17A Circuit electrode

[0169] 18A 1st conduction section

[0170] 18B 1st conduction section

[0171] 19A Second conduction section

[0172] 19B Second conduction section

[0173] 21 Support

[0174] 22 Support

[0175] 23 Support

[0176] 24 Insulation layer

[0177] 25 Soldering Department

[0178] 26 Soldering Department

[0179] 27 Soldering Department

[0180] 31 1st connection

[0181] 32 Second connection

[0182] 33 Secondary battery

[0183] 34 Charger

[0184] 35 Switching element

Claims

1. A protection element, have: A first fuse element and a second fuse element connected in series, a heater connected between the first fuse element and the second fuse element, a first electrode portion connected to the first fuse element on the side opposite to the second fuse element, a second electrode portion connected to the second fuse element on the side opposite to the first fuse element, and a third electrode portion connected between the first fuse element and the second fuse element and connected in series with the heater, The protective circuit is configured such that when an overcurrent flows through the first fuse element and the second fuse element or an overvoltage is applied to a secondary battery connected to the protective circuit, the first fuse element is disconnected before the second fuse element. The first electrode portion has thermal characteristics different from thermal characteristics of the second electrode portion, The thermal characteristics of the first electrode portion and the thermal characteristics of the second electrode portion include at least one of thermal resistance and thermal capacitance.

2. A protection element, comprising: A first fuse element and a second fuse element connected in series, a heater connected between the first fuse element and the second fuse element, a first electrode portion connected to the first fuse element on the side opposite to the second fuse element, a second electrode portion connected to the second fuse element on the side opposite to the first fuse element, and a third electrode portion connected between the first fuse element and the second fuse element and connected in series with the heater, The protective circuit is configured such that when an overcurrent flows through the first fuse element and the second fuse element or an overvoltage is applied to a secondary battery connected to the protective circuit, the first fuse element is disconnected before the second fuse element. Further having: a first conductive portion for conducting the first electrode portion with an external circuit, and a second conductive portion for conducting the second electrode portion with an external circuit, The first conductive portion has a thermal characteristic different from a thermal characteristic of the second conductive portion, The thermal characteristics of the first conductive portion and the thermal characteristics of the second conductive portion include at least one of thermal resistance and thermal capacitance.

3. The protection element according to claim 1 or 2, The first fuse element has a thermal characteristic different from a thermal characteristic of the second fuse element, The thermal characteristics of the first fuse element and the thermal characteristics of the second fuse element include at least one of thermal resistance and thermal capacitance.

4. The protection element according to claim 3, wherein the length of the first fuse element is longer than the length of the second fuse element, the cross-sectional area of ​​the first fuse element in the width direction is smaller than the cross-sectional area of ​​the second fuse element in the width direction, and / or the thermal conductivity of the material forming the first fuse element is smaller than the thermal conductivity of the material forming the second fuse element. 5 . The protection element according to claim 1 , wherein the thermal conductivity of a material forming the first electrode portion is lower than the thermal conductivity of a material forming the second electrode portion. 6 . The protection element according to claim 2 , wherein the widthwise cross-sectional area of ​​the first conductive portion is smaller than the widthwise cross-sectional area of ​​the second conductive portion, and / or the thermal conductivity of a material forming the first conductive portion is smaller than the thermal conductivity of a material forming the second conductive portion.

7. A protection circuit comprising a plurality of protection elements connected in parallel, Each protection element constituting the plurality of protection elements has: A first fuse element and a second fuse element connected in series, a heater connected between the first fuse element and the second fuse element, a first electrode portion connected to the first fuse element on the side opposite to the second fuse element, a second electrode portion connected to the second fuse element on the side opposite to the first fuse element, and a third electrode portion connected between the first fuse element and the second fuse element and connected in series with the heater, The plurality of first fuse elements constituting the plurality of protection elements are connected to the same pole, The invention is configured such that when an overcurrent flows through the first fuse element and the second fuse element respectively constituting the plurality of protection elements or an overvoltage is applied to a secondary battery connected to the protection circuit, the first fuse element in the protection element is disconnected before the second fuse element. The first electrode portion has a thermal characteristic different from a thermal characteristic of the second electrode portion, The thermal characteristics of the first electrode portion and the thermal characteristics of the second electrode portion include at least one of thermal resistance and thermal capacitance.

8. A protection circuit comprising a plurality of protection elements connected in parallel, Each protection element constituting the plurality of protection elements has: A first fuse element and a second fuse element connected in series, a heater connected between the first fuse element and the second fuse element, a first electrode portion connected to the first fuse element on the side opposite to the second fuse element, a second electrode portion connected to the second fuse element on the side opposite to the first fuse element, and a third electrode portion connected between the first fuse element and the second fuse element and connected in series with the heater, The plurality of first fuse elements constituting the plurality of protection elements are connected to the same pole, The invention is configured such that when an overcurrent flows through the first fuse element and the second fuse element respectively constituting the plurality of protection elements or an overvoltage is applied to a secondary battery connected to the protection circuit, the first fuse element in the protection element is disconnected before the second fuse element. Each protection element constituting the plurality of protection elements further comprises: a first conductive portion for conducting the first electrode portion with an external circuit, and a second conductive portion for conducting the second electrode portion with an external circuit, The first conductive portion has a thermal characteristic different from a thermal characteristic of the second conductive portion, The thermal characteristics of the first conductive portion and the thermal characteristics of the second conductive portion include at least one of thermal resistance and thermal capacitance.

9. The protection circuit according to claim 7 or 8, The first fuse element has a thermal characteristic different from a thermal characteristic of the second fuse element, The thermal characteristics of the first fuse element and the thermal characteristics of the second fuse element include at least one of thermal resistance and thermal capacitance.

10. The protection circuit according to claim 9, wherein the length of the first fuse element is longer than the length of the second fuse element, the cross-sectional area of ​​the first fuse element in the width direction is smaller than the cross-sectional area of ​​the second fuse element in the width direction, and / or the thermal conductivity of the material forming the first fuse element is greater than the thermal conductivity of the material forming the second fuse element. 11 . The protection circuit according to claim 7 , wherein the thermal conductivity of the material forming the first electrode portion is smaller than the thermal conductivity of the material forming the first electrode portion.

12. The protection circuit according to claim 8, wherein the widthwise cross-sectional area of ​​the first conductive portion is smaller than the widthwise cross-sectional area of ​​the second conductive portion, and / or the thermal conductivity of a material forming the first conductive portion is smaller than the thermal conductivity of a material forming the second conductive portion.

13. The protection circuit according to claim 7 or 8, Further possesses: a plurality of first connecting portions disposed between the plurality of first electrode portions and an external circuit, and a plurality of second connection portions disposed between the plurality of second electrode portions and an external circuit, the first connection portion connected to the first fuse element constituting each of the plurality of protection elements has a thermal characteristic different from a thermal characteristic of the second connection portion connected to the second fuse element of the protection element, The thermal characteristics of the first connection portion and the thermal characteristics of the second connection portion include at least one of thermal resistance and thermal capacitance. 14 . The protection circuit according to claim 13 , wherein the length of the first connection portion is longer than the length of the second connection portion, and / or the cross-sectional area of ​​the first connection portion in the width direction is smaller than the cross-sectional area of ​​the second connection portion in the width direction.

Images