TW201601180A - Fuse element - Google Patents

Abstract

Provided is a fuse element which can safely open an electric circuit in response to abnormalities such as water leaks. This fuse element is provided with a fuse element (11) and electrodes (12) which are arranged in proximity to the fuse element (11) and which comprise a metal with an ionization tendency lower than that of the fuse element (11). By this means, if for example water enters between the fuse element (11) and the electrode (12), the electric circuit can be opened safely because the current rating of the fuse element (11) decreases due to the electrolytic corrosion action.

Description

Fuse element

The present invention relates to a fuse element that is blown by Joule heat to open a circuit when a relatively large current is passed.

In recent years, most of mobile phones, notebook computers, and the like have used lithium ion secondary batteries. Lithium-ion secondary batteries have high weight and energy density. Therefore, in order to ensure the safety of users and electronic equipment, several protection circuits such as overcharge protection and over-discharge protection are built into the battery pack, and the battery is installed under certain conditions. The output of the package is occluded. However, when the positive electrode/negative electrode insulation fitting portion of the battery is corroded by water immersion, the pressure inside the battery leaks, and the safety valve does not function properly, resulting in an accident.

There is a patch for detecting the wetted trace with respect to water immersion to issue a warning (see, for example, Patent Document 1), but since it is not intended to limit the use of the battery, there is a possibility that the circuit substrate is immersed in water. Circuit malfunction caused by migration (insulation degradation) or short circuit. Further, the leakage of the electrolyte caused by the abnormality of the battery may cause the same disadvantage as described above.

[Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 11-144695

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2000-162081

The present invention has been made in view of the above circumstances, and an object thereof is to provide a fuse element which can safely open an electric circuit for an abnormality such as water immersion or battery liquid leakage.

In order to solve the above problems, a fuse element according to the present invention includes: a fuse unit; and an electrode formed of a metal disposed close to the fuse unit and having a smaller ionization tendency than the fuse unit.

According to the present invention, when water is immersed between the fuse element and the electrode, the current rating is lowered because the resistance of the fuse element is increased by the galvanic action, so that the circuit can be safely opened.

10‧‧‧Fuse components

11‧‧‧Fuse unit

12‧‧‧ electrodes

21A, 21B, 21C‧‧‧1st to 3rd fuse units

22A, 22B, 22C, 22D‧‧‧1st to 4th electrodes

23A, 23B, 23C, 23D, 23E, 23F‧‧‧1st to 6th separation layers

30‧‧‧Battery pack

30a‧‧‧positive terminal

30b‧‧‧Negative terminal

31~34‧‧‧ battery unit

35‧‧‧Battery stack

36‧‧‧Detection circuit

37‧‧‧Protection components

38‧‧‧ Current control components

40‧‧‧Charge and discharge control circuit

41,42‧‧‧ Current control components

43‧‧‧Control Department

45‧‧‧Charging device

Fig. 1 is a perspective view showing a configuration example of a fuse element.

Figure 2 is a perspective view showing the fuse element before electro-corrosion.

Figure 3 is a perspective view showing the fuse element after electrolytic etching.

Fig. 4 is a perspective view showing a configuration example of a fuse element in which a plurality of fuse units are arranged in parallel.

Fig. 5 is a cross-sectional view showing a configuration example of a fuse element in which a plurality of fuse units are arranged in parallel.

Fig. 6 is a block diagram showing an application example of a circuit for using a fuse element in a battery pack of a lithium ion secondary battery.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings in the following order.

1. Configuration example of fuse element

2. Application examples of fuse components

<1. Configuration Example of Fuse Element>

The fuse element of the present embodiment includes a fuse unit and an electrode which is formed of a metal which is disposed close to the fuse unit and has a smaller ionization tendency than the fuse unit. Since the fuse unit is close to the electrode, the liquid intrudes between the fuse unit and the electrode in the event of an abnormality such as water immersion or battery liquid leakage, and the fuse unit generates electrical corrosion. As a result, the rated current value is lowered by the increase in the resistance, so that the current can be interrupted by the current supplied to the fuse unit, and the circuit can be safely opened.

Fig. 1 is a perspective view showing a configuration example of a fuse element. The fuse element 10 includes an electrode 12A, 12B in which the fuse unit 11 composed of a flat plate and the central portion of the fuse unit 11 face each other. The fuse unit 11 and the electrode 12 are close to each other so that the water can be immersed, and the distance is preferably 0.01 mm to 10 mm. Further, when the distance between the fuse unit 11 and the electrode 12 is small, the electric field intensity is large and the electric erosion effect is increased. Therefore, in order to open the circuit more efficiently, the distance between the electrodes 12 is set to 0.01 to 1 mm. good.

The fuse unit 11 has a predetermined rated current value, and is blown after the current exceeding the rated current value is energized. The fuse unit 11 is preferably made of any one selected from the group consisting of aluminum, iron, nickel, tin, and lead. In the present specification, the term "main component" means 50% by weight or more based on the total mass of the material.

Further, the electrodes 12A, 12B are disposed to face the center portion of the fuse unit 11 in the facing direction. The electrodes 12A, 12B are preferably arranged to cover the entire surface of the central portion of the fuse unit 11 so that the quality of the material eroded by the fuse unit 11 is large.

Further, the electrodes 12A, 12B are preferably made of gold having a smaller ionization tendency than the fuse unit. The genus is composed of any one selected from the group consisting of gold, platinum, silver, copper, and palladium. Thereby, when water intrudes between the fuse unit 11 and the electrode 12, the fuse unit 11 made of a base metal becomes a positive electrode and is ionized (corroded), and the fuse unit 11 is tapered or pinholes are generated, and melting can be performed. The conductor impedance of the wire unit 11 rises, causing the rated current value to decrease.

Further, it is preferable to provide a separation layer between the fuse unit 11 and the electrode 12. Further, the separation layer is preferably made of an insulator such as a mesh or a porous material. Thereby, the direct short circuit between the fuse unit 11 and the electrode 12 can be suppressed, and the retainability of water or electrolyte can be ensured. Further, the separation layer preferably carries an electrolyte such as NaCl. Thereby, the electrical conductivity of the water or electrolyte can be improved and the electrical erosion can be promoted.

Further, a water absorbing or hygroscopic insulator may be disposed between the fuse unit 11 and the electrode 12. Further, an insulator made of a sol, a gel or a solid may be disposed between the fuse unit 11 and the electrode 12, and conductivity may be expressed by water. Further, when the electrolyte composed of the sol or the gel intrudes between the fuse unit 11 and the electrode 12, the galvanic action of the fuse unit 11 can be exerted.

Further, the fuse unit 11 is preferably connected as a positive electrode, and the electrode 12 is preferably connected as a negative electrode. Thereby, the electrolytic corrosion reaction can be promoted, and the rated current value of the fuse unit 11 can be quickly lowered.

That is, the fuse element 10 constitutes a blocking circuit including: a fuse unit 11 which is connected in series as a positive electrode to a direct current power source; and an electrode 12 which is disposed close to the fuse unit 11 and has a tendency to ionize The wire unit 11 is made of a small metal and is connected as a negative electrode. Further, the first terminal and the second terminal for energizing the fuse unit 11 and the third terminal for connecting the electrode 12 as a negative electrode are provided, and the first terminal and the second terminal are connected in series to the energization path of the positive electrode, and the third terminal is provided. The terminals are connected to the negative pole or to ground.

2 and 3 respectively show the stand of the fuse unit before and after the electric erosion. Body map. As shown in FIG. 2, the fuse unit 11 before the electro-corrosion maintains a short shape. When water intrudes between the fuse unit 11 and the electrode 12, as shown in FIG. 3, the fuse unit 11 made of a base metal becomes a positive electrode and is ionized (corroded), and the fuse unit 11 is tapered or pinholes are generated. Therefore, the conductor impedance of the fuse unit 11 rises and the rated current value decreases. The water or the electrolyte between the fuse unit 11 and the electrode 12 sometimes evaporates due to the rise in heat of the conductor, but since the rated current value is lowered, the current can be supplied to the fuse unit 11 by itself. Interrupt, safely open the circuit.

Further, the fuse element is not limited to the above-described configuration example. For example, a plurality of fuse units may be arranged in parallel, and the electrodes may be disposed between the fuse units. 4 is a perspective view showing a configuration example of a fuse element in which a plurality of fuse units are arranged in parallel, and FIG. 5 is a cross-sectional view showing a configuration example of a fuse element in which a plurality of fuse units are arranged in parallel. As shown in FIG. 5, the fuse element has a first electrode 22A, a first separation layer 23A, a first fuse unit 21A, a second separation layer 23B, a second electrode 22B, and a third separation layer 23C. 2 fuse unit 21B, fourth separation layer 23D, third electrode 22C, fifth separation layer 23E, third fuse unit 21C, sixth separation layer 23F, and fourth electrode 22D.

The first to third fuse units 21A, 21B, and 21C, the first to fourth electrodes 22A, 22B, 22C, and 22D, and the first to sixth separation layers 23A, 23B, 23C, 23D, 23E, and 23F are respectively The fuse unit 11, the electrode 12, and the separation layer described above are the same, and the description thereof is omitted here.

As described above, by juxtaposing the fuse units in plurality, it is possible to increase the rated current and to promote the erosion of the fuse unit when water invades between the fuse unit and the electrode.

<2. Application Example of Fuse Element>

Fig. 6 is a block diagram showing an application example of a circuit for using a fuse element in a battery pack of a lithium ion secondary battery. The fuse element 10 is used, for example, as being assembled in the battery pack 30 as shown in FIG. The battery pack 30 has, for example, a battery stack 35 composed of battery cells 31 to 34 of a total of four lithium ion secondary batteries.

The battery pack 30 includes a battery stack 35, a charge and discharge control circuit 40 that controls charging and discharging of the battery stack 35, a fuse element 10 that blocks an output of the battery stack 35 during an abnormality, and a voltage of each of the battery cells 31 to 34 are detected. Detection circuit 36.

The battery stack 35 is required to be connected in series in order to protect the battery cells 31 to 34 from being overcharged and overdischarged, and is detachably connected to the charging via the positive terminal 30a and the negative terminal 30b of the battery pack 30. The device 45 is applied with a charging voltage from the charging device 45. The electronic device can be operated by connecting the positive terminal 30a and the negative terminal 30b of the battery pack 30 charged by the charging device 45 to an electronic device that operates by the battery.

The charge and discharge control circuit 40 includes two current control elements 41 and 42 connected in series to a current path flowing from the battery stack 35 to the charging device 45, and a control unit 43 that controls the operation of the current control elements 41 and 42. The current control elements 41, 42 are composed of, for example, field effect transistors (hereinafter referred to as FETs), and the control unit 43 controls the gate voltage to control the conduction and the interruption of the current path of the battery stack 35. The control unit 43 operates by receiving power supply from the charging device 45, and controls the operation of the current control elements 41 and 42 so as to interrupt the current path when the battery stack 35 is over-discharged or overcharged in response to the detection result of the detection circuit 36.

The fuse element 10 includes a first terminal and a second terminal for energizing the fuse unit 11, and a third terminal for connecting the electrode 12 as a negative electrode. For example, the first terminal and the second terminal are connected to the battery stack 35 and the charge. The third terminal is connected to the negative electrode side in the charge and discharge current path between the discharge control circuits 40.

The detecting circuit 36 is connected to each of the battery cells 31 to 34 to detect each battery cell. The voltage values of the elements 31 to 34 cause the signal to be output to the current control element 38 when an abnormality occurs, and the charge and discharge current path is blocked by the action of the protection element 37.

The protection element 37 is connected, for example, to a charge and discharge current path between the battery stack 35 and the charge and discharge control circuit 40, and its operation is controlled by the current control element 38. The protective element 10 has a circuit structure composed of a fusible conductor and a heating element that is energized by a connection point of the fusible conductor to generate heat by melting the fusible conductor, and the fusible conductor is connected in series to the charge and discharge current path, and the heating element Connected to current control element 38.

The current control element 38, by the detection signal outputted from the detection circuit 36, causes the protection element 37 to operate when the voltage value of the battery cells 31-34 becomes a voltage exceeding a predetermined over-discharge or over-charge state, to control the battery The charge and discharge current path of the stack 35 is interrupted regardless of the switching action of the current control elements 41, 42.

According to the above application example, water intrudes between the fuse unit 11 and the electrode 12 in the event of an abnormality such as water leakage, and the fuse unit 11 is electrically etched. Thereby, since the rated current value is lowered, the current can be automatically blocked by the current supplied to the fuse unit 11, and the circuit can be safely opened.

Further, as long as the circuit can be opened with good efficiency in the above abnormality, and the fuse unit 11 is connected as a positive electrode and the electrode 12 is connected as a negative electrode, the connection target of the third terminal of the fuse element 10 is not particularly limited. For example, it is possible to detect that water intrudes between the fuse unit 11 and the electrode 12 by using the connection target of the third terminal as the detection circuit 36. Further, for example, a primary battery may be used, and the positive electrode side may be connected to the fuse unit 11 and the negative electrode side may be connected to the third terminal. Alternatively, the third terminal can be grounded. Further, since only two metals having different ionization tendencies in principle are immersed in the electrolytic solution, the metal having a large ionization tendency is electrically etched, so that the third terminal can be made to be in an open state.

10‧‧‧Fuse components

11‧‧‧Fuse unit

12A, 12B‧‧ ‧ electrodes

Claims (17)

A fuse element comprising: a fuse unit; and an electrode formed of a metal disposed close to the fuse unit and having a smaller ionization tendency than the fuse unit. The fuse element of claim 1, wherein the fuse unit is selected from any one selected from the group consisting of aluminum, iron, nickel, tin, and lead; and the electrode is selected from the group consisting of gold, platinum, and silver. Any one of copper and palladium is used as a main component. The fuse element according to claim 1 or 2, wherein the fuse unit is formed of a flat plate, and the electrode system and the central portion of the fuse unit face each other. A fuse element according to claim 1 or 2, wherein a separation layer is provided between the fuse unit and the electrode. A fuse element according to claim 3, wherein a separation layer is provided between the fuse unit and the electrode. The fuse element of claim 4, wherein the separation layer is composed of an electrolyte. A fuse element according to claim 5, wherein the separation layer is composed of an electrolyte. The fuse element according to claim 1 or 2, wherein the fuse unit is arranged in parallel, and the electrode is disposed between the fuse units. The fuse element of claim 3, wherein the fuse unit is arranged in parallel, and the electrode is disposed between the fuse units. The fuse element of claim 4, wherein the fuse unit is arranged in parallel, and the electrode is disposed between the fuse units. The fuse element of claim 6, wherein the fuse unit is arranged in parallel, and the electrode is disposed between the fuse units. A fuse element according to claim 1 or 2, wherein the fuse unit is connected as a positive electrode; and the electrode is connected as a negative electrode. The fuse element of claim 3, wherein the fuse unit is connected as a positive electrode; and the electrode is connected as a negative electrode. The fuse element of claim 4, wherein the fuse unit is connected as a positive electrode; and the electrode is connected as a negative electrode. The fuse element of claim 6, wherein the fuse unit is connected as a positive electrode; and the electrode is connected as a negative electrode. A fuse element according to item 8 of the patent application, wherein the fuse unit is positive The electrodes are connected; the electrodes are connected as a negative electrode. A blocking circuit comprising: a fuse unit in which a positive electrode is connected in series to a DC power supply; and an electrode which is formed of a metal disposed close to the fuse unit and having a smaller ionization tendency than the fuse unit, and is connected as a negative electrode.