JP7444587B2 - Protection elements and protection circuits - Google Patents

Description

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 charging/discharging circuit for a secondary battery.

Conventionally, protection circuits have been implemented in various mobile devices equipped with secondary batteries, such as mobile phones and portable computers. A mobile device equipped with a conventional protection circuit includes, for example, a power storage device (secondary battery), a plurality of protection circuits, and first and second output terminals, and the protection circuits are connected in series. When an external circuit is connected to the first and second output terminals, a discharge current is supplied from the power storage device to the external circuit, and a discharge current is supplied from the external circuit to the power storage device. There is a secondary battery device configured such that a charging current supplied to the device flows through two series-connected fuse elements in the plurality of protection circuits (Patent Document 1).

This secondary battery device has a heater whose one end is connected to a connection point between fuse elements, the other end of each heater is connected to one end of a rectifying element, and the other end of each rectifying element is connected to the other end of each heater. , a switch element is connected, and when the switch element becomes conductive, a current flows through the switch element and each rectifying element to the heater of each protection circuit. In addition, in this secondary battery device, at least two rectifying elements are inserted in the middle of the current path that connects the terminals of the heater of the protection circuit, and when a short circuit current flows and one fuse element is blown, Even if a voltage difference occurs between the terminals of the heaters of the two protection circuits, at least one rectifying element is reverse biased. Therefore, no current flows from the heater terminal of one protection circuit to the heater terminal of the other protection circuit, and no residual current is generated thereby.

In addition, as a conventional protection element, a plurality of fuse elements are arranged between a plurality of electrodes that are input to a current-carrying path, and the current is cut off by blowing out the fuse elements due to heat generated by an energized heating element. Proposed. In this protection element, when electricity is applied from a specific current-carrying path to which a specific fuse element is connected among the plurality of fuse elements, the other fuse elements are blown out before the specific fuse element. Furthermore, the blowing time of the plurality of fuse elements is controllable. The specific electrode to which the specific fuse element is connected is the electrode that is the input of the current-carrying path among the plurality of electrodes, and the blowing time of the specific fuse element is the same as that of the other fuses. The distance from each of the plurality of fuse elements to the heating element is configured to be different so that the fuse element has a longer time than the melting time of the element (Patent Document 2).

Japanese Patent Application Publication No. 2004-193000 Japanese Patent Application Publication No. 2010-165685

However, in the protection circuit of Patent Document 1, in order to prevent overcurrent in the entire system, it is necessary to mount a plurality of rectifier elements (diodes) in one-to-one correspondence with a plurality of heaters, resulting in a complicated device configuration. Moreover, there is a problem that the manufacturability is not good and the manufacturing cost is high.

Furthermore, the protection element of Patent Document 2 has a configuration in which a "fuse element that always blows last" can be specified within one protection element, and current is not supplied from at least the current-carrying path to which that fuse element is connected. If there is, all other fuse elements are blown first to stop the heat generation of the heating resistor, which prevents overcurrent and overvoltage in multiple protection circuits connected in parallel. This is not an issue, and it cannot be said to be sufficient to prevent overcurrent and overvoltage.

In addition, in recent years, as mobile devices have become even more sophisticated and functional, the charging capacity of secondary batteries has further increased. A protection circuit is required.

The purpose of the present invention is to improve safety by reliably preventing overcurrent and overvoltage with a simpler device configuration than before, and to provide protection that can achieve good manufacturability and cost reduction. The purpose of the present invention is to provide elements and protection circuits.

In order to achieve the above object, the present invention provides the following means.
[1] 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 a side of the first fuse element opposite to the second fuse element;
a second electrode portion connected to a side of the second fuse element opposite to the first fuse element;
a third electrode part connected between the first fuse element and the second fuse element and connected in series with the heater;
has
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 a protection circuit, the first fuse element A protection element that is configured to be shut off before the
[2] The first fuse element has thermal characteristics different from thermal characteristics of the second fuse element,
The protection element according to [1] above, wherein 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 capacity.
[3] The first fuse element and the second fuse element are fuse elements,
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 is smaller than the cross-sectional area of the second fuse element, and/or , The protection element according to [2] above, wherein the thermal conductivity of the material forming the first fuse element is lower than the thermal conductivity of the material forming the second fuse element.
[4] The first electrode portion has thermal characteristics different from those of the second electrode portion,
The protection element according to any one of [1] to [3] above, wherein 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 heat capacity.
[5] The protection element according to [4] above, wherein the thermal conductivity of the material forming the first electrode part is lower than the thermal conductivity of the material forming the second electrode part.
[6] a first conduction section that connects the first electrode section and an external circuit;
a second conductive part that conducts the second electrode part and an external circuit;
It further has
The first conductive portion has thermal characteristics different from the thermal characteristics of the second conductive portion,
The protection element according to any one of [1] to [5] above, wherein 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 heat capacity.
[7] The cross-sectional area in the width direction of the first conductive part is smaller than the cross-sectional area in the width direction of the second conductive part, and/or the thermal conductivity of the material forming the first conductive part is lower than the second conductive part. The protective element according to [6] above, which has a thermal conductivity lower than that of the material forming the conductive portion.
[8] A protection circuit including a plurality of protection elements connected in parallel,
Each protection element constituting the plurality of protection elements is
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 a side of the first fuse element opposite to the second fuse element;
a second electrode portion connected to a side of the second fuse element opposite to the first fuse element;
a third electrode part connected between the first fuse element and the second fuse element and connected in series with the heater;
has
A plurality of the first fuse elements constituting the plurality of protection elements are connected to the same polarity,
When an overcurrent flows through the first fuse element and the second fuse element constituting each of the plurality of protection elements, or when an overvoltage is applied to a secondary battery connected to a protection circuit, A protection circuit, wherein the first fuse element in the protection element is cut off before the second fuse element.
[9] The first fuse element has thermal characteristics different from those of the second fuse element,
The protection circuit according to [8] above, wherein 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 capacity.
[10] Whether the length of the first fuse element is longer than the length of the second fuse element, or whether 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, and/or the protection circuit according to [9] above, wherein the resistivity of the material forming the first fuse element is greater than the resistivity of the material forming the second fuse element.
[11] The first electrode portion has thermal characteristics different from those of the second electrode portion,
The protection circuit according to any one of [8] to [10], wherein 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 heat capacity.
[12] The protection circuit according to [11] above, wherein the thermal conductivity of the material forming the first electrode part is lower than the thermal conductivity of the material forming the first electrode part.
[13] Each protection element constituting the plurality of protection elements is
a first conduction part that connects the first electrode part and an external circuit;
a second conductive portion that connects the second electrode portion and an external circuit;
It further has
The first conductive portion has thermal characteristics different from the thermal characteristics of the second conductive portion,
The protection circuit according to any one of [8] to [12] above, wherein 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 heat capacity.
[14]
The cross-sectional area in the width direction of the first conductive part is smaller than the cross-sectional area in the width direction of the second conductive part, and/or the thermal conductivity of the material forming the first conductive part is lower than that of the second conductive part. The protection circuit according to [13] above, which has a thermal conductivity lower than the thermal conductivity of the material forming it.
[15] A plurality of first connection portions arranged between the plurality of first conduction portions and the external circuit;
a plurality of second connection portions arranged between the plurality of second conduction portions and the external circuit;
further comprising;
The first connection portion connected to the first conduction portion of each of the plurality of protection elements has thermal characteristics different from the thermal characteristics of the second connection portion connected to the second conduction portion of the protection element. has
The protection circuit according to any one of [8] to [14], wherein 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 heat capacity.
[16] The length of the first connecting portion is longer than the length of the second connecting portion, and/or the cross-sectional area of the first connecting portion is greater than the cross-sectional area of the second connecting portion in the width direction. The protection circuit according to [15] above, wherein the protection circuit is also small.

According to the present invention, it is possible to improve safety by reliably preventing overcurrent and overvoltage with a simpler device configuration than conventional ones, and in addition, it is possible to realize good manufacturability and cost reduction.

FIG. 1 is a plan view schematically showing the configuration of a protection element according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view of the protection element taken along section line II-II in FIG. FIG. 3 is a plan view schematically showing the configuration of a protection element according to a second embodiment of the present invention. FIG. 4 is a plan view schematically showing the configuration of a protection element according to a third embodiment of the present invention. FIG. 5 is a cross-sectional view of the protection element taken along section line VV in FIG. 4. FIG. 6 is a plan view schematically showing the configuration of a protection element according to a fourth embodiment of the present invention. FIG. 7 is a plan view schematically showing the configuration of a protection element according to a fifth embodiment of the present invention. FIG. 8 is a plan view schematically showing the configuration of a protection element according to a sixth embodiment of the present invention. FIG. 9 is a cross-sectional view of the protection element taken along cutting line IX-IX in FIG. 8. FIG. 10 is a plan view schematically showing the configuration of a protection element according to a seventh embodiment of the present invention. FIG. 11 is a cross-sectional view of the protection element taken along section line XI-XI in FIG. FIG. 12 is a plan view schematically showing the configuration of a protection circuit according to an eighth embodiment of the present invention. FIG. 13 is a circuit diagram illustrating the operation of the protection circuit of FIG. 12, and shows the state before the cutoff operation. FIG. 14 is a circuit diagram illustrating the operation of the protection circuit of FIG. 12, and shows the state after the cutoff operation.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a plan view schematically showing the configuration of a protection element according to a first embodiment of the present invention, and FIG. 2 is a sectional view of the protection element taken along cutting line II-II in FIG.
As shown in FIGS. 1 and 2, 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, and a first fuse element 12A and a second fuse element 13A connected in series on the substrate 11. 13A, a first electrode part 15A connected to the opposite side of the first fuse element 12A from the second fuse element 13A, and a first fuse element 12A of the second fuse element 13A. A second electrode portion 16A connected to the opposite side, 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, and the first electrode It has a first conductive portion 18A that conducts between the portion 15A and the external circuit, and a second conductive portion 19A that connects the second electrode portion 16A and the external circuit. This protection element 10 is activated 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 (see FIGS. 13 and 14) connected to the protection circuit. When the first fuse element 12A is opened, the first fuse element 12A is cut off before the second fuse element 13A. The configuration and operation when an overvoltage is applied to the secondary battery connected to the protection circuit will be described later.

The substrate 11 is not particularly limited as long as it is made of an insulating material, and includes, for example, substrates used in printed wiring boards such as ceramic substrates and glass epoxy substrates, as well as glass substrates, resin substrates, and insulated metal substrates. etc. can be used. Note that among these, a ceramic substrate, which is an insulating substrate with excellent heat resistance and good thermal conductivity, is suitable.

The first fuse element 12A and the second fuse element 13A are integrally formed in this embodiment, and are connected to the first electrode part 15A and the second electrode part through three conductive supports 21, 22, 23. 16A and the third electrode section 17.
The first fuse element 12A and the second fuse element 13A may be configured as separate members. Further, the shapes of the first fuse element 12A and the second fuse element 13A are flaky, but are not limited to this, and may be rod-shaped.

The first fuse element 12A has thermal characteristics different from those of the second fuse element 13A, and the thermal characteristics of the first fuse element 12A and the thermal characteristics of the second fuse element 13A are at least one of thermal resistance and thermal capacity. Contains. Thermal resistance (K/W) means the ease with which heat is transferred, and the larger the thermal resistance, the more difficult it is to transfer heat (Thermal resistance [K/W] = Length [m] / {Cross-sectional area [m ² ] x Thermal conductivity [W/(m・K)]}). Further, heat capacity (J/K) means the amount of heat required to raise the unit temperature, that is, the ease with which the temperature changes, and the larger the heat capacity, the more difficult the temperature changes. Therefore, for example, (1) the thermal resistance of the first fuse element 12A is greater than the thermal resistance of the second fuse element 13A, or (2) the heat capacity of the first fuse element 12A is greater than the heat capacity of the second fuse element 13A. (3) It is preferable that both of the above (1) and (2) are satisfied.

Specifically, the first fuse element 12A and the second fuse element 13A have, for example, a thin piece shape. In this embodiment, the length of the first fuse element 12A is longer than the length of the second fuse element 13A. In this case, since the thermal resistance of the first fuse element 12A is larger than that of the second fuse element 13A, when an overcurrent flows through the first fuse element 12A and the second fuse element 13A, the first fuse element 12A is cut off before the second fuse element 13A.

As the material constituting the first fuse element 12A and the second fuse element 13A, various low melting point metals conventionally used as fuse materials can be used. Examples of the low melting point metal include SnSb alloy, BiSnPb alloy, BiPbSn alloy, BiPb alloy, BiSn alloy, SnPb alloy, SnAg alloy, PbIn alloy, ZnAl alloy, InSn alloy, PbAgSn alloy, and the like. The materials constituting the first fuse element 12A and the second fuse element 13A are preferably the same, but may be different.

The heater 14 is arranged on the substrate 11 and directly under the third electrode section 17. An insulating layer 24 is arranged between the heater 14 and the third electrode section 17. The heater 14 has one end connected to the heater lead-out electrode part 14A, and the other end connected to the third electrode part 17 via the lead-out electrode part 17A.

The heater 14 is made by applying a resistance paste made of a conductive material such as ruthenium oxide or carbon black, and an inorganic binder such as water glass or an organic binder such as a thermosetting resin, and baking the paste as necessary. formed by. Further, the heater 14 may be formed by using a thin film of ruthenium oxide, carbon black, or the like through printing, plating, vapor deposition, or sputtering processes, or may be formed by pasting or laminating these films.

The first electrode section 15A, the second electrode section 16A, and the third electrode section 17 are electrodes into which the melted first fuse element 12A or second fuse element 13A flows, respectively. The materials constituting the first electrode part 15A, the second electrode part 16A, and the third electrode part 17 are not particularly limited, and have good wettability with the molten first fuse element 12A or second fuse element 13A. Examples include metals. For example, the first electrode portion 15A, the second electrode portion 16A, and the third electrode portion 17 may be made of a simple metal such as copper, or at least the surface thereof may be made of Ag, Ag-Pt, Ag-Pd, Au, or the like. You can use whatever you have. The first electrode section 15A and the second electrode section 16A are connected to a first connection section and a second connection section, which will be described later, via solder sections 25 and 26, respectively. Further, the third electrode portion 17 is connected to a third connection portion (not shown) via a solder portion 27. As with the first electrode part 15A, the second electrode part 16A, and the third electrode part 17, the material constituting the heater lead-out electrode part 14A and the lead-out electrode part 17A may be a single metal such as copper, or a material with at least a surface of Ag, Those formed from Ag--Pt, Ag--Pd, Au, etc. can be used. Further, the heater lead-out electrode portion 14A is connected to a switching element, which will be described later, via a solder portion 27.

The first conductive portion 18A and the second conductive portion 19A are, for example, through holes, and are formed by filling the inner peripheral surface of a through hole formed in the substrate 11 with a conductor. Examples of the material constituting the first conductive portion 18A and the second conductive portion 19A include silver, copper, tungsten, and alloys thereof. The first conductive portion 18A and the second conductive portion 19A may have a configuration other than a through hole as long as the configuration allows conduction with an external circuit. Furthermore, the protection element 10 may have a configuration that does not include the first conductive portion 18A and the second conductive portion 19A.

FIG. 3 is a plan view schematically showing the configuration of a protection element according to a second embodiment of the present invention. The protection element according to the second 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. Explain the different parts.

As shown in FIG. 3, 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 in the width direction of the first fuse element 12B is smaller than the cross-sectional area in the width direction of the second fuse element 13B, and the thermal resistance of the first fuse element 12B is larger than the thermal resistance of the second fuse element 13B. , when an overcurrent flows through the first fuse element 12B and the second fuse element 13B, or when an overvoltage is applied to the secondary battery connected to the protection circuit, the first fuse element 12B switches to the second fuse element 12B. It is cut off before 13B.

The length of the first fuse element 12B is the same as the length of the second fuse element 13B, but is not limited to this, and even if the length of the first fuse element 12B is longer than the length of the second fuse element 13B. good. Thereby, the thermal resistance of the first fuse element 12B can be made even larger than the thermal resistance of the second fuse element 13B.

FIG. 4 is a plan view schematically showing the configuration of a protection element according to a third embodiment of the present invention, and FIG. 5 is a sectional view of the protection element taken along cutting line VV in FIG. 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.

As shown in FIGS. 4 and 5, in the third embodiment, the thickness of the first fuse element 12C may 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. Also in this configuration, the cross-sectional area in the width direction of the first fuse element 12C is smaller than the cross-sectional area in the width direction of the second fuse element 13C, and the thermal resistance of the first fuse element 12C is larger 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 when an overvoltage is applied to the secondary battery connected to the protection circuit, the first fuse element 12C closes to the second fuse element 12C. It is shut off before element 13C.

The length of the first fuse element 12C is the same as the length of the second fuse element 13C, but is not limited to this, and even if the length of the first fuse element 12C is longer than the length of the second fuse element 13C. good. Further, the width of the first fuse element 12C is the same as the width of the second fuse element 13C, but the width is not limited to this, and the width of the first fuse element 12C may be smaller than the width of the second fuse element 13C. good. Thereby, the thermal resistance of the first fuse element 12C can be made even larger than the thermal resistance of the second fuse element 13C.

FIG. 6 is a plan view schematically showing the configuration 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 configurations of the first and second fuse elements are different.

As shown in FIG. 6, 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 forming the first fuse element 12D may be smaller than the number of fuse elements forming the second fuse element 13D. Also in this configuration, the total cross-sectional area in the width direction of the plurality of fuse elements 12d is smaller than the total cross-sectional area in the width direction of the plurality of fuse elements 13d, and the thermal resistance of the first fuse element 12D is lower than the thermal resistance of the second fuse element 13D. Since the resistance is larger than the resistance, when an overcurrent flows through the first fuse element 12D and the second fuse element 13D, or when an overvoltage is applied to the secondary battery connected to the protection circuit, the first fuse element 12D is cut off before the second fuse element 13D.

The length of the first fuse element 12D is the same as the length of the second fuse element 13D, but is not limited to this, and the length of the first fuse element 12D may be longer than the length of the second fuse element 13D. . Further, 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 is not limited to this. It may be smaller than the width of 13d. Furthermore, the thickness of the first fuse element 12D may be smaller than the thickness of the second fuse element 13D. Thereby, the thermal resistance of the first fuse element 12D can be made even larger than the thermal resistance of the second fuse element 13D.

FIG. 7 is a plan view schematically showing the configuration 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 configurations of the first and second fuse elements are different.

As shown in FIG. 7, in the fifth embodiment, the thermal conductivity of the material forming the first fuse element 12E may be lower than the thermal conductivity of the material forming the second fuse element 13E. Also in this configuration, since the thermal resistance of the first fuse element 12E is larger than the thermal resistance of the second fuse element 13E, when an overcurrent flows through the first fuse element 12E and the second fuse element 13E, or when the protection circuit When an overvoltage is applied to the connected secondary battery, the first fuse element 12E is cut off before the second fuse element 13E.

The length of the first fuse element 12E is the same as the length of the second fuse element 13E, but is not limited to this, and even if the length of the first fuse element 12E is longer than the length of the second fuse element 13E. good. Further, the width of the first fuse element 12E is the same as the width of the second fuse element 13E, but the width is not limited to this, and the width of the first fuse element 12E may be smaller than the width of the second fuse element 13E. good. Furthermore, the thickness of the first fuse element 12E may be smaller than the thickness of the second fuse element 13E. Thereby, the thermal resistance of the first fuse element 12E can be made even larger than the thermal resistance of the second fuse element 13E.

In this way, 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, or the first fuse element 12A is longer than the second fuse element 13A. The cross-sectional area of the 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 lower than that of the second fuse element 13B (13C, 13D). It is preferable that the thermal conductivity is lower than the thermal conductivity of the material forming the fuse element 13E. As a result, 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 the When overvoltage is applied to the battery, the first fuse element 12A (12B, 12C, 12D, 12E) is reliably cut off before the second fuse element 13A (13B, 13C, 13D, 13E), making it extremely simple. With this configuration, safety can be further improved.

FIG. 8 is a plan view schematically showing the configuration of a protection element according to a sixth embodiment of the present invention, and FIG. 9 is a sectional view of the protection element taken along cutting line IX-IX in FIG. 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 parts are different.

As shown in FIGS. 8 and 9, in the sixth embodiment, the first electrode section 15B has thermal characteristics different from those of the second electrode section 16B, and the thermal characteristics of the first electrode section 15B and The thermal characteristics of the second electrode portion 16B may include at least one of thermal resistance and thermal capacity. For example, (1) the thermal resistance of the first electrode part 15B is greater than the thermal resistance of the second electrode part 16B, or (2) the heat capacity of the first electrode part 15B is smaller than the heat capacity of the second electrode part 16B. or (3) it is preferable that both of the above (1) and (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.

In this embodiment, the thermal conductivity of the material forming the first electrode part 15B is lower than the thermal conductivity of the material forming the second electrode part 16B. In this case, since the thermal resistance of the first electrode section 15B is larger than the thermal resistance of the second electrode section 16B, when an overcurrent flows through the first fuse element 12A and the second fuse element 13A, the first fuse element 12A is cut off before the second fuse element 13A, and safety can be further improved with an extremely simple configuration.

FIG. 10 is a plan view schematically showing the configuration of a protection element according to a seventh embodiment of the present invention, and FIG. 11 is a sectional view of the protection element taken along cutting line XI-XI in 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 parts are different.

As shown in FIGS. 10 and 11, in the sixth embodiment, the first conductive portion 18B has thermal characteristics different from the thermal characteristics of the second conductive portion 19B, and the thermal characteristics of the first conductive portion 18B and the The thermal characteristics of the two conductive portions 19B may include at least one of thermal resistance and heat capacity. For example, (1) the thermal resistance of the first conductive part 18B is greater than the thermal resistance of the second conductive part 19B, or (2) the heat capacity of the first conductive part 18B is smaller than the heat capacity of the second conductive part 19B. or (3) it is preferable that 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.

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. , when an overcurrent flows through the first fuse element 12A and the second fuse element 13A, the first fuse element 12A is cut off before the second fuse element 13A.

Further, the thermal conductivity of the material forming the first conductive portion 18B may be lower than the thermal conductivity of the material forming the second conductive portion 19B. Thereby, the thermal resistance of the first conductive portion 18B can be made even larger than the thermal resistance of the second conductive portion 19B. When the thermal conductivity of the material forming the first conducting part 18B is smaller than the thermal conductivity of the material forming the second conducting part 19B, the width of the first conducting part 18B is smaller than the width of the second conducting part 19B. Although a smaller width is preferable, it may be the same width as the second conductive portion 19B.

In this way, the cross-sectional area in the width direction of the first conductive part 18B is smaller than the cross-sectional area in the width direction of the second conductive part 19B, and/or the thermal conductivity of the material forming the first conductive part 18B is the second. Since the thermal conductivity is lower than that of the material forming the conductive portion 19B, when an overcurrent flows through the first fuse element 12A and the second fuse element 13A, the first fuse element 12A has a higher thermal conductivity than the second fuse element 13A. It is reliably shut off first, and with an extremely simple configuration, safety can be further improved.

[Configuration of protection circuit]
FIG. 12 is a plan view schematically showing the configuration of a protection circuit according to an eighth embodiment of the present invention. The eighth embodiment will be described using an example in which a protection circuit includes a plurality of protection elements 10 of the first embodiment.

As shown in FIG. 12, the protection circuit 1 includes a plurality of protection elements 10, 10, 10 connected in parallel, a plurality of protection elements arranged between a plurality of first electrode parts 15A, 15A, 15A, and an external circuit. and a plurality of second connection parts 32, 32, 32 arranged between the plurality of second electrode parts 16A, 16A, 16A and the external circuit. There is.

The first connecting portions 31, 31, 31 are connected to the first electrode portions 15A, 15A, 15A via a plurality of solder portions 25, 25, 25, respectively. Further, the second connecting portions 32, 32, 32 are connected to the second electrode portions 16A, 16A, 16A via a plurality of solder portions 26, 26, 26, respectively. The plurality of first connection parts 31, 31, 31 and the plurality of second connection parts 32, 32, 32 are, for example, circuit patterns mounted on a board. The material constituting the plurality of first connection parts 31, 31, 31 and the plurality of second connection parts 32, 32, 32 is not particularly limited, and examples thereof include copper or a copper alloy.

The plurality of first fuse elements 12A, 12A, 12A constituting the plurality of protection elements 10, 10, 10 are connected to the same polarity, and the first fuse element configuring each of the plurality of protection elements 10, 10, 10 12A and the second fuse element 13A, the first fuse element 12A in the protection element is cut off before the second fuse element 13A.

Further, in the present embodiment, the first connection portion 31 connected to the first fuse element 12A constituting each of the plurality of protection elements 10, 10, 10 is connected to the second fuse element 13A of the protection element 10. The second connecting portion 32 has thermal characteristics different from those of the second connecting portion 32 . Preferably, the thermal characteristics of the first connecting portion 31 and the thermal characteristics of the second connecting portion 32 include at least one of thermal resistance and heat capacity. For example, (1) the thermal resistance of the first connection part 31 is greater than the thermal resistance of the second connection part 32, or (2) the heat capacity of the first connection part 31 is smaller than the heat capacity of the second connection part 32. or (3) it is preferable that both of the above (1) and (2) are satisfied. The meaning of the thermal characteristics of the first connecting portion 31 and the second connecting portion 32 is the same as the meaning of the thermal characteristics of the first and second fuse elements described in the first embodiment.

In this embodiment, the width of the plurality of first connection parts 31, 31, 31 is smaller than the width of the plurality of second connection parts 32, 32, 32. In this case, the cross-sectional area in the width direction of the first connecting part 31 is smaller than the cross-sectional area in the width direction of the second connecting part 32, and the thermal resistance of the first connecting part 31 is larger than the thermal resistance of the second connecting part 32. , 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 connected to the protection circuit, the first fuse element 12A disconnects from the second fuse element 13A. will be blocked earlier.

As described above, the first connecting portion 31 is connected to the first electrode portion 15A via the solder portion 25 and the through hole or the through hole, and the shape and material of the solder portion 25 may vary. Therefore, the thermal characteristics of the first connecting portion 31 may include the thermal characteristics of the joining member such as the solder portion 25. do. Similarly, the thermal characteristics of the second connecting portion 32 can include the thermal characteristics of a joining member such as the solder portion 26. The meaning of the thermal characteristics of the joining member is the same as the meaning of the thermal characteristics of the first and second fuse elements described in the first embodiment.

13 and 14 are circuit diagrams illustrating the operation of the protection circuit 1 of FIG. 12, with FIG. 13 showing the state before the cutoff operation, and FIG. 14 showing the state after the cutoff operation.

In the protection circuit 1, as shown in FIG. 13, for example, the 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. It is connected. Further, the plurality of second connection parts 32, 32, 32 are connected to the parallel connection point B via an external circuit, and are also connected to the positive electrode of the charger 34. The heater 14 connected to the third electrode section 17 is connected to both the negative electrodes of the secondary batteries 33, 33 and the negative electrode of the charger 34, respectively. A switching element 35 such as an FET is provided downstream of the plurality of third electrode sections 17 . That is, the heater 14 located downstream of the plurality of third electrode sections has one end connected to the switching element 35 via the heater lead-out electrode section 14A, and the other end connected to the lead-out electrode section 17A and the third electrode section 17A. It is connected to the first fuse element 12A and the second fuse element 13A via the three-electrode portion 17.

When charging the secondary batteries 33, 33, power is supplied from the charger 34 to the secondary batteries 33, 33 via an external circuit. Furthermore, when the secondary batteries are discharged, power is supplied from the secondary batteries 33, 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 both when charging and discharging the secondary batteries 33, 33.

If overcurrent or overvoltage occurs for some reason when charging or discharging the secondary batteries 33, 33, the thermal resistance of the first connecting portion 31 is greater than the thermal resistance of the second connecting portion 32, so the As shown, the first fuse element 12A is cut off before the second fuse element 13A. In all of the plurality of protection elements 10, 10, 10, the first fuse element 12A is cut off before the second fuse element 13A, so that the circuit on the secondary battery 33 side and the circuit on the charger 34 side are disconnected. The circuit is separated. This prevents current from flowing backward through the heater 14, and there is no need to provide a rectifying element such as a diode between the plurality of protection elements 10, 10, 10 and the switching element 35.

In this embodiment, the length of the plurality of first connection parts 31, 31, 31 is the same as the length of the plurality of second connection parts 32, 32, 32, but is not limited to this. The lengths of the portions 31, 31, 31 may be different from the lengths of the plurality of second connecting portions 32, 32, 32. Thereby, the thermal resistance of the first connecting portion 31 can be made even larger than the thermal resistance of the second connecting portion 32.

Furthermore, in the present embodiment, the widths of the plurality of first connection parts 31, 31, 31 are different from the widths of the plurality of second connection parts 32, 32, 32, but the width is not limited to this. When the width of the plurality of first connection parts 31, 31, 31 is the same as the width of the plurality of second connection parts 32, 32, 32, the length of the plurality of first connection parts 31, 31, 31 is The length may be different from the length of the plurality of second connecting portions 32, 32, 32.

Further, the protection circuit 1 may include a detection element (not shown) connected to each of the secondary batteries 33 and 33 and to the switching element 35. This detection element constantly monitors whether there is a high voltage state, particularly an overvoltage, and outputs a control signal to the switching element 35 when the high voltage state occurs. In this case, the switching element 35 causes the heater 14 to generate heat by causing the current from the secondary battery 33 to flow through the heater 14 in accordance with the control signal. As a result, the first fuse element 12A is blown out before the second fuse element 13A.

In this way, the length of the first connecting part 31 is longer than the length of the second connecting part 32, and/or the widthwise cross-sectional area of the first connecting part 31 is larger than the widthwise cross-sectional area of the second connecting part 32. 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 The element 12A is reliably cut off before the second fuse element 13A, and safety can be further improved with an extremely simple configuration.

In this embodiment, the protection circuit 1 includes the protection element 10 of the first embodiment, but is not limited to this, and may include the protection elements of the second to seventh embodiments. In that case as well, the thermal resistance of the first fuse element provided in each protection element can be made larger than the thermal resistance of the second fuse element.

Further, in the present embodiment, in the protection circuit 1, the thermal characteristics of the first connection portion 31 are different from the thermal characteristics of the second connection portion 32, but the present invention is not limited to this, and the protection element 10 is In this case, the thermal characteristics of the first connecting portion 31 may be the same as the thermal characteristics of the second connecting portion 32. For example, the cross-sectional area in the width direction of the plurality of first connecting parts 31, 31, 31 may be the same as the cross-sectional area in the width direction of the plurality of second connecting parts 32, 32, 32; The thermal conductivity of the connecting parts 31, 31, 31 may be the same as the thermal conductivity of the plurality of second connecting parts 32, 32, 32.

As described above, according to the 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 elements 12A (12B, 12C, 12D, 12E) are activated by the second fuse elements 13A (13B, 13C, 13D, 13E). ), one of the first fuse elements 12A (12B, 12C, 12D, 12E) is It is possible to interrupt the circuit on one side and the circuit on the other side. Therefore, when forming a protection circuit including a plurality of protection elements 10 connected in parallel, the plurality of first fuse elements 12A (12B, 12C, 12D, 12E) constituting the plurality of protection elements 10 are connected to the same polarity. This makes it possible to reliably prevent overcurrent and overvoltage without providing a rectifying element such as a diode. Therefore, it is possible to reliably prevent overcurrent and overvoltage and improve safety with a simpler configuration than the conventional protection element 10, and in addition, it is possible to realize good manufacturability and cost reduction.

Further, according to the above embodiment, in a protection circuit including a plurality of protection elements 10 connected in parallel, a plurality of first fuse elements 12A constituting a plurality of protection elements 10 are connected to the same polarity, and a plurality of When an overcurrent flows through the first fuse element 12A (12B, 12C, 12D, 12E) and the second fuse element 13A (13B, 13C, 13D, 13E) constituting each of the protection elements 10, or when the protection circuit 1 When an overvoltage is applied to the secondary battery 33 connected to Since the first fuse element 12A (12B, 12C, 12D, 12E) is configured to be cut off before the The circuit on the other side (for example, the circuit on the charger side) can be cut off from the circuit on the other side (for example, the circuit on the charger side). Therefore, overcurrent and overvoltage can be reliably prevented without providing multiple rectifying elements such as diodes. Therefore, the protection circuit 1 can have a simpler configuration than the conventional one, and can reliably prevent overcurrent and overvoltage to improve safety, and can also realize good manufacturability and cost reduction.

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 can be made within the scope of the gist of the present invention described within the scope of the claims. is possible.

For example, in the above embodiments, 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 connection parts are different from each other. Not limited. The electrical conductor resistance values (electrical 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 connection parts are different from each other. You can leave it there. Also with this configuration, 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, the first fuse element It can be configured to be cut off before the second fuse element, and thereby the same effect as described above can be achieved.

1 Protection circuit 10 Protection element 11 Substrate 12A First fuse element 12B First fuse element 12C First fuse element 12D First fuse element 12d Fuse element 12E First fuse element 13A Second fuse element 13B Second fuse element 13C Second fuse Element 13D Second fuse element 13d Fuse element 13E Second fuse element 14 Heater 14A Heater lead-out electrode part 15A First electrode part 15B First electrode part 16A Second electrode part 16B Second electrode part 17 Third electrode part 17A Lead-out electrode part 18A First conductive part 18B First conductive part 19A Second conductive part 19B Second conductive part 21 Support 22 Support 23 Support 24 Insulating layer 25 Solder part 26 Solder part 27 Solder part 31 First connection part 32 Second connection Section 33 Secondary battery 34 Charger 35 Switching element

Claims (14)

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 a side of the first fuse element opposite to the second fuse element;
a second electrode portion connected to a side of the second fuse element opposite to the first fuse element;
a third electrode part connected between the first fuse element and the second fuse element and connected in series with the heater;
has
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 a protection circuit, the first fuse element It is configured to be blocked before the
The first electrode portion has thermal characteristics different from thermal characteristics of the second electrode portion,
A protection element , wherein the thermal characteristics of the first electrode part and the thermal characteristics of the second electrode part include at least one of thermal resistance and heat capacity . 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 a side of the first fuse element opposite to the second fuse element;
a second electrode portion connected to a side of the second fuse element opposite to the first fuse element;
a third electrode part connected between the first fuse element and the second fuse element and connected in series with the heater;
has
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 a protection circuit, the first fuse element It is configured to be blocked before the
a first conduction part that connects the first electrode part and an external circuit;
a second conductive part that conducts the second electrode part and an external circuit;
It further has
The first conductive portion has thermal characteristics different from the thermal characteristics of the second conductive portion,
The protection element, wherein 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 heat capacity. the first fuse element has thermal characteristics different from thermal characteristics of the second fuse element;
The protection element according to claim 1, wherein 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 capacity. 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 is smaller than the cross-sectional area of the second fuse element, and/or 4. The protection element according to claim 3 , wherein the thermal conductivity of the material forming the first fuse element is lower than the thermal conductivity of the material forming the second fuse element. The protection element according to claim 1 , wherein the thermal conductivity of the material forming the first electrode part is lower than the thermal conductivity of the material forming the second electrode part. The cross-sectional area in the width direction of the first conductive part is smaller than the cross-sectional area in the width direction of the second conductive part, and/or the thermal conductivity of the material forming the first conductive part is lower than that of the second conductive part. 3. The protective element according to claim 2 , which has a thermal conductivity lower than that of the material from which it is formed. A protection circuit comprising a plurality of protection elements connected in parallel,
Each protection element constituting the plurality of protection elements is
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 a side of the first fuse element opposite to the second fuse element;
a second electrode portion connected to a side of the second fuse element opposite to the first fuse element;
a third electrode part connected between the first fuse element and the second fuse element and connected in series with the heater;
has
A plurality of the first fuse elements constituting the plurality of protection elements are connected to the same polarity,
When an overcurrent flows through the first fuse element and the second fuse element constituting each of the plurality of protection elements, or when an overvoltage is applied to a secondary battery connected to a protection circuit, The first fuse element in the protection element is configured to be cut off before the second fuse element,
The first electrode portion has thermal characteristics different from thermal characteristics of the second electrode portion,
A protection circuit , wherein the thermal characteristics of the first electrode part and the thermal characteristics of the second electrode part include at least one of thermal resistance and heat capacity . A protection circuit comprising a plurality of protection elements connected in parallel,
Each protection element constituting the plurality of protection elements is
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 a side of the first fuse element opposite to the second fuse element;
a second electrode portion connected to a side of the second fuse element opposite to the first fuse element;
a third electrode part connected between the first fuse element and the second fuse element and connected in series with the heater;
has
A plurality of the first fuse elements constituting the plurality of protection elements are connected to the same polarity,
When an overcurrent flows through the first fuse element and the second fuse element constituting each of the plurality of protection elements, or when an overvoltage is applied to a secondary battery connected to a protection circuit, The first fuse element in the protection element is configured to be cut off before the second fuse element,
Each protection element constituting the plurality of protection elements is
a first conduction part that connects the first electrode part and an external circuit;
a second conduction part that connects the second electrode part and an external circuit;
It further has
The first conductive portion has thermal characteristics different from the thermal characteristics of the second conductive portion,
The protection circuit, wherein the thermal characteristics of the first conductive part and the thermal characteristics of the second conductive part include at least one of thermal resistance and heat capacity. A protection circuit comprising a plurality of protection elements connected in parallel,
Each protection element constituting the plurality of protection elements is
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 a side of the first fuse element opposite to the second fuse element;
a second electrode portion connected to a side of the second fuse element opposite to the first fuse element;
a third electrode part connected between the first fuse element and the second fuse element and connected in series with the heater;
has
A plurality of the first fuse elements constituting the plurality of protection elements are connected to the same polarity,
When an overcurrent flows through the first fuse element and the second fuse element constituting each of the plurality of protection elements, or when an overvoltage is applied to a secondary battery connected to a protection circuit, The first fuse element in the protection element is configured to be cut off before the second fuse element,
a plurality of first connection parts disposed between the plurality of first electrode parts and an external circuit;
a plurality of second connection parts disposed between the plurality of second electrode parts and an external circuit;
further comprising;
The first connection portion connected to the first fuse element constituting each of the plurality of protection elements has different thermal characteristics from the second connection portion connected to the second fuse element of the protection element. has thermal properties,
The protection circuit, wherein 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 heat capacity. the first fuse element has thermal characteristics different from thermal characteristics of the second fuse element;
The protection circuit according to claim 7 , wherein 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 capacity. 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 is smaller than the cross-sectional area of the second fuse element, and/or 11. The protection circuit according to claim 10 , wherein 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. The protection circuit according to claim 7 , wherein the thermal conductivity of the material forming the first electrode part is lower than the thermal conductivity of the material forming the first electrode part. The cross-sectional area in the width direction of the first conductive part is smaller than the cross-sectional area in the width direction of the second conductive part, and/or the thermal conductivity of the material forming the first conductive part is lower than that of the second conductive part. 9. The protection circuit according to claim 8 , which has a thermal conductivity lower than that of the material from which it is formed. The length of the first connecting portion is longer than the length of the second connecting portion, and/or the cross-sectional area of the first connecting portion is smaller than the cross-sectional area of the second connecting portion. The protection circuit according to claim 9 .

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