JP4979422B2 - Current limiting member and battery pack including the current limiting member - Google Patents

Description

  The present invention relates to a current limiting member for limiting the current of a plurality of electric circuits, and the current limiting member, a mobile computer such as a video camera, a notebook personal computer, and a PDA (personal digital assistant), a cellular phone, and an MP3 player. The present invention relates to a battery pack comprising a battery such as a chargeable / dischargeable non-aqueous electrolyte secondary battery used as a power source for portable electronic devices.

  2. Description of the Related Art In recent years, chargeable / dischargeable rectangular parallelepiped nonaqueous electrolyte secondary batteries are mainly used as power sources for portable electric devices such as video cameras, mobile computers, and mobile phones that are rapidly spreading.

  For example, a nonaqueous electrolyte secondary battery such as a lithium ion secondary battery includes an electrode group in which a positive electrode and a negative electrode are wound via a separator, and a nonaqueous electrolyte housed in a case made of aluminum or an aluminum alloy. One side of this battery is provided with a protection circuit board having a protection circuit for controlling battery voltage and current in order to prevent overcharge and overdischarge, and these are housed in a case made of synthetic resin. A battery pack is attached to a portable electrical device. The protective circuit board and the battery are electrically connected by connecting leads.

FIG. 5 is a partially broken plan view showing a battery core 21 of a battery pack used as a power source for a PDA or the like, which is a premise of the present invention.
In the battery core 21, a battery 22 and a battery 23 are connected in parallel.
The batteries 22 and 23 are rectangular parallelepiped, and include a power generation element in which a positive electrode and a negative electrode are wound via a separator, for example, a nonaqueous electrolyte secondary battery such as a lithium ion secondary battery, and the power generation element is made of aluminum. Alternatively, it is housed in an aluminum alloy case. Negative electrodes 22 a and 23 a are provided on one side of each of the batteries 22 and 23. The whole of the batteries 22 and 23 other than the portion where the negative terminals 22a and 23a are provided is the positive electrode (terminal).
In a front view, the one side surface on which the negative electrode terminal 23a of the battery 23 is provided is retracted from the one side surface on which the negative electrode terminal 22a of the battery 22 is provided, that is, the batteries 22 and 23 are arranged side by side. The battery 22 and the battery 23 are connected in a state where a step is provided in a direction crossing the direction.

An insulating tape 24 is attached to each side surface of the batteries 22 and 23. The insulating tape 24 is provided with a projecting hole for projecting the negative terminal 22a, 23a corresponding to the negative terminal 22a, 23a, and the negative terminal 22a, 23a projects from the projecting hole.
The negative terminals 22a and 23a are connected to electrodes of PTC elements 25 and 26 as protective elements via leads 27 and 28, respectively. The PTC elements 25 and 26 are thermal elements that limit the current of the charge / discharge circuit when an excessive current such as a short circuit current flows and when the temperature of the batteries 22 and 23 rises.

The other electrode provided on the back surface of the PTC element 26 is connected to one end of the lead 29. The lead 29 is curved outward and has the other end connected to the lead 30.
The other end of the lead 30 is provided with a board connecting portion 30 a for connecting to the electrode of the protection circuit board 34 disposed on the one side surface of the battery 22. The lead 30 is bent along the step, and is connected to a lead 31 connected to the other electrode provided on the back surface of the PTC element 25 at a flat portion of the bent portion on the protective element 26 side.
An insulating tape 32 is interposed between the lead 27 and the lead 30 on the side of the board connecting portion 30a in order to prevent a short circuit. An insulating tape 33 is interposed between the lead 28, the lead 30 connection side portion of the lead 29, and the lead 30.
A protection circuit for preventing overcharge and overdischarge of the batteries 22 and 23 is mounted on the protection circuit board 34. The other electrode of the protection circuit board 34 is connected to the electrode connection portion 35 a of the lead 35, and the other end portion of the lead 35 is connected to the other side surface of the battery 22.

In Patent Document 1, a plurality of secondary batteries are connected by intermediate leads on one short side and a positive lead and a negative lead are connected to the other short side via a bimetal. An invention of a battery pack in which batteries are connected in series and parallel is disclosed.
JP 2004-273221 A

In the battery core 21 of FIG. 5 and the battery pack of Patent Document 1, as described above, a PTC element is connected to the terminal of each battery, a large number of leads are required to connect the PTC element, and complicated wiring is required. It was necessary.
In the battery core 21 of FIG. 5, when the PTC element 26 is arranged on the battery 22 side from the negative electrode terminal 23a, the PTC element 26 is connected to the other electrode of the PTC element 26 within a narrow range along the stepped portion. The lead, the lead connected to the other electrode of the PTC element 25, and the lead for connecting to the protection circuit board must be connected, which makes connection difficult. Therefore, the PTC element 26 is arranged on the opposite side of the battery 22 with respect to the negative electrode terminal 23a, bypassing the leads, the number of leads and insulating tapes is increased, and the arrangement of members is complicated.
Along with this, the number of welding points has increased.

  The present invention has been made in view of such circumstances, and when an excessive current flows through the electrical element or when the temperature of the electrical element rises, the protective elements that limit the current of the electrical element are L-shaped. Or a T-shaped common lead, and the extension of the common lead from the linear base is connected to an electrical protection circuit that controls the battery voltage and current. It is an object of the present invention to provide a current limiting member that can reduce the number and the number of insulating tapes interposed between leads and reduce the number of assembly steps.

  Further, according to the present invention, a notch or a hole is provided on the connection side of the extension part with the electrical protection circuit, so that the extension part is connected to the electrode of the protection circuit board on which the electrical protection circuit is mounted by resistance welding. An object of the present invention is to provide a current limiting member that suppresses the flow of reactive current in the surface direction of the extending portion.

  Further, the present invention is configured such that a common lead of the current limiting member is arranged along the adjacent side surfaces of the two batteries arranged side by side, and the extension portion of the current limiting member is connected to the electrical protection circuit. Therefore, it is possible to reduce the number of leads and the number of insulating tapes interposed between the leads, reduce the number of assembling steps, and reduce the number of welded parts, thereby providing a battery pack with improved reliability. Objective.

  In the present invention, when two batteries are provided side by side with a step, the leads of the current limiting member are arranged along the step portion of the battery, thereby connecting the leads at the step portion. It is an object of the present invention to provide a battery pack that does not need to be routed and does not need to be disposed around a lead, and can be easily wired.

  The current limiting member according to the first aspect of the present invention is an L-shaped or T-shaped protective element that limits the current of the electrical element when an excessive current flows through the electrical element or when the temperature of the electrical element rises. The common lead is connected, and the extended portion of the common lead from the linear base portion is connected to the electrical protection circuit.

  In the present invention, since a plurality of protection elements are connected in advance with a common lead, the number of leads is compared with the case where each protection element is connected to each of the electrical circuits after each protection element is separately arranged in the electric circuit. In addition, the number of insulating tapes interposed between the leads can be reduced, and the number of assembly steps can be reduced.

  The current limiting member according to a second aspect of the present invention is characterized in that, in the first aspect, a notch or a hole is provided on a connection side of the extension portion with the electrical protection circuit.

  In the present invention, since the notch or the hole is provided on the connection portion of the extension portion with the electrical protection circuit, the connection portion of the protection circuit board on which the electrical protection circuit is mounted is connected to connect the extension portion to the electrical protection circuit. In the case of resistance welding with the electrode, when the welding electrode is applied to both sides of the notch or the hole and energized, it is suppressed that the reactive current flows in the surface direction of the extending portion.

  A battery pack according to a third aspect of the present invention has a rectangular parallelepiped shape, and includes two batteries arranged in parallel, the current limiting member of the first or second aspect, and a protection circuit board on which an electrical protection circuit is mounted, The common lead of the current limiting member is disposed along the side surfaces adjacent to both the batteries, and the extension portion is connected to the electrical protection circuit.

In the present invention, since the protection elements that limit the currents of the two batteries are individually connected and integrated in advance with a common lead, the two protection elements are connected in series with the positive terminal or the negative terminal of each battery. In this state, common leads can be arranged along the adjacent side surfaces of both batteries, so that the number of leads can be reduced, and the number of insulating tapes interposed between the leads can be reduced accordingly. it can.
In addition, since both the protection elements are connected to the electrical protection circuit by the extended portion of the common lead, the number of members can be further reduced. Therefore, the cost can be reduced.
And since a member is reduced, an assembly man-hour can also be reduced.
Furthermore, since the number of welded portions is reduced, the reliability is improved.

  According to a fourth aspect of the present invention, there is provided the battery pack according to the third aspect, wherein the two batteries are arranged side by side with a step in a direction crossing the side-by-side direction.

In the present invention, for a battery pack in which two batteries are arranged side by side, two common leads for connecting the protection elements are connected in a state where each protection element is connected in series with the positive electrode terminal or the negative electrode terminal of each battery. It suffices to arrange them along the stepped portions of the individual batteries, and there is no need to connect the leads at the stepped portions, and there is no need to place the leads around, thereby simplifying the wiring.
And since two protection elements can be arrange | positioned adjacently on both sides of a level | step-difference part, compactization is achieved.

  According to the current limiting member of the first invention, when an excessive current flows through the electrical element, or when the temperature of the electrical element rises, the protective elements that limit the current of the electrical element are L-shaped or T-shaped. Since the common lead of the common lead is connected so that the extended portion of the common lead from the linear base is connected to the electric protection circuit, each protection element is arranged in the electric circuit separately. Thereafter, compared to the case where each protection element is connected by leads, the number of leads and the number of insulating tapes interposed between the leads can be reduced, and the number of assembly steps can be reduced.

  According to the current limiting member of the second invention, since the notch or the hole is provided on the connection side of the extension portion with the electrical protection circuit, the extension portion is protected by resistance welding and the protection circuit in which the electrical protection circuit is mounted. When connecting with the electrode of a board | substrate, it is suppressed that a reactive current flows into the surface direction of an extension part.

According to the battery pack of the third invention, the common lead of the current limiting member is arranged along the adjacent side surfaces of the two batteries arranged side by side, and the extension portion is connected to the electrical protection circuit. Therefore, the number of leads and the number of insulating tapes interposed between the leads can be reduced, and the number of assembly steps can also be reduced. Therefore, the cost can be reduced.
And since the number of welding points is reduced, the reliability is improved.

  According to the battery pack of the fourth invention, when two batteries are arranged side by side with a step, the common lead of the current limiting member is arranged along the step portion of the battery. Therefore, it is not necessary to connect the leads at the stepped portion, and it is not necessary to place the leads by detouring, thereby simplifying the wiring.

Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.
Embodiment 1 FIG.
1 is a partially broken perspective view showing a battery core 1 of a battery pack according to Embodiment 1 of the present invention, FIG. 2 is a partially broken plan view showing a battery core 1, and FIG. 3 is a perspective view showing a current limiting member 4. FIG.

The battery core 1 is used as a power source for a PDA or the like, and a battery 2 and a battery 3 as electrical elements are connected in parallel.
The batteries 2 and 3 have a rectangular parallelepiped shape, and a negative electrode formed by applying a negative electrode mixture to a copper current collector and a positive electrode formed by applying a positive electrode mixture to an aluminum current collector are wound through a separator. Nonaqueous electrolyte secondary battery including a rotated flat wound electrode group (not shown) and a nonaqueous electrolyte solution (not shown), specifically, a secondary battery such as a lithium ion secondary battery The power generation element is housed in a case made of aluminum or aluminum alloy.
Negative electrodes 2 a and 3 a are provided on one side of each of the batteries 2 and 3. The entire batteries 2 and 3 other than the portion where the negative terminals 2a and 3a are provided are used as positive electrodes (terminals).
When viewed from the front, the one side surface (hereinafter referred to as a negative electrode protruding surface) where the negative electrode terminal 3a of the battery 3 is provided is retracted from the negative electrode protruding surface where the negative electrode terminal 2a of the battery 2 is provided. That is, the battery 2 and the battery 3 are connected in a state where a step is provided in a direction crossing the direction in which the batteries 2 and 3 are juxtaposed.

An insulating tape 5 is attached to each negative electrode projecting surface of the batteries 2 and 3. The insulating tape 5 is provided with terminal through holes 5a and 5a corresponding to the negative terminals 2a and 3a, and the negative terminals 2a and 3a protrude from the terminal through holes 5a and 5a.
An insulating tape 8 is attached to the battery 3 side of the flat end of the battery 2.

As shown in FIG. 3, in the current limiting member 4, the electrode provided on the front surface of the PTC element 41 and the electrode provided on the back surface of the PTC element 42 are connected by an L-shaped common lead 43. . The other electrode provided on the back surface of the PTC element 41 is connected to the lead 44, and the other electrode provided on the surface of the PTC element 42 is connected to the lead 45.
The PTC elements 41 and 42 are thermal elements that limit the current of the charge / discharge circuit when an excessive current such as a short circuit current flows and when the temperature of the batteries 22 and 23 rises.
The L-shaped bottom side portion of the common lead 43 (extending portion from the linear base portion of the common lead 43) is a substrate connection portion 43a that is connected to an electrode of the protection circuit board 6 described later, and is on the end side. A notch 43b is provided.

  As shown in FIGS. 1 and 2, in the battery core 1, the negative electrode terminal 2 a and the lead 44 are connected to bring the PTC element 41 into close contact with the negative electrode protruding surface of the battery 2, and the common lead 43 extends along the step portion. The PTC element 42 is brought into close contact with the negative electrode projecting surface of the battery 3 and the lead 45 is connected to the negative electrode terminal 3a.

On the surface of the substrate 61 of the protection circuit board 6, positive and negative external output terminals 63, 63, 63 are provided by gold plating for taking out electric power to the outside and conversely taking in electric power from outside for charging. .
A protection circuit 62 for preventing overcharge and overdischarge of the batteries 2 and 3 is mounted on the back surface of the substrate 61.
And the electrode provided in the one end part of the board | substrate 61 and the said board | substrate connection part 43a are connected by resistance welding (spot welding). As described above, since the notch 43b is provided in the board connecting portion 43a, the reactive current is applied in the surface direction of the board connecting portion 43a when the welding electrode is applied to both sides of the notch 43b during resistance welding and energized. Is suppressed from flowing. In addition, in order to acquire the same effect, you may decide to provide a hole instead of the notch 43b.
Further, the other electrode provided at the other end of the substrate 61 is connected to the electrode connecting portion 7 a of the lead 7. The other end of the lead 7 is connected to the other side of the battery 2.
As a result, the protective circuit board 6 is arranged to face the negative electrode projecting surface of the battery 2.

  The battery core 1 configured as described above has a shape that allows the connected batteries 2 and 3 to be fitted therein, and is housed in a synthetic resin case (not shown) that is open on one side. . Then, a cover (not shown) having a frame shape that covers the outer periphery of the flat surfaces of the batteries 2 and 3 and exposes the flat portions of the batteries 2 and 3 other than the outer periphery is covered with a label (see FIG. The battery pack is configured by covering the flat portion and the side surfaces of the batteries 2 and 3 by not shown.

  In the battery core 1 according to the present embodiment, since the PTC elements 41 and 42 are connected in advance by the common lead 43, the PTC elements 41 and 42 are connected in series with the negative terminals 2a and 3a of the batteries 2 and 3. In such a state, it is sufficient to arrange the lead along the stepped portions of the batteries 2 and 3, and the lead arrangement is complicated by bypassing the lead as in the battery core 21 having the conventional stepped portion shown in FIG. In other words, the PTC elements 41 and 42 can be arranged adjacent to each other with a stepped portion interposed between the negative electrode terminals 2a and 3a.

That is, in the battery core 21, the leads 29, 30, 31 and three leads are necessary to connect the PTC elements 25, 26 and the protection circuit board 34, and the insulating tapes 32, 33 are necessary. In the present embodiment, the lead for connecting the PTC elements 41 and 42 and the protection circuit board 6 is only one lead with the common lead 43, and the length thereof is short, so that the space can be saved and the battery core can be saved. Leads to higher energy density. Further, an insulating tape interposed between the leads is not necessary.
Accordingly, the number of members and the number of assembly steps can be reduced, and the cost can be reduced.
Further, since the number of welded portions is reduced, the reliability is improved.

  In the above-described embodiment, the case where the battery 3 is connected to the battery 2 in a state where there is a step is described. However, the present invention is not limited to this, and the negative electrode protruding surfaces of the battery 2 and the battery 3 are provided. The batteries 2 and 3 may be connected in the aligned state, and the current limiting member 4 may be disposed on the negative electrode projecting surface.

Embodiment 2. FIG.
FIG. 4 is a perspective view showing a current limiting member 14 of the battery pack according to Embodiment 2 of the present invention. In the figure, the same parts as those in FIG.

In the current limiting member 14, an electrode provided on the surface of the PTC element 41 and an electrode provided on the back surface of the PTC element 42 are connected by a T-shaped common lead 46. The other electrode provided on the back surface of the PTC element 41 is connected to the lead 44, and the other electrode provided on the surface of the PTC element 42 is connected to the lead 45.
A T-shaped protruding portion of the common lead 46 (a portion extending from the linear base portion of the common lead 46) is a board connecting portion 46a connected to the electrode of the protection circuit board, and a notch 46b is formed on the end side. Is provided.

The current limiting member 14 is arranged on two parallel batteries similar to those in the first embodiment and the battery core 1.
That is, the negative electrode terminal 2 a of the battery 2 and the lead 44 are connected to bring the PTC element 41 into close contact with the negative electrode protruding surface of the battery 2, the common lead 46 is brought into close contact with the stepped portion, and the PTC element 42 is connected to the battery 3. The lead 45 is connected to the negative electrode terminal 3 a of the battery 3 in close contact with the negative electrode protruding surface. The connection is similarly performed when the negative electrode projecting surfaces of the battery 2 and the battery 3 are aligned in a direction crossing the juxtaposed direction.

And the electrode provided in the one end part of the protection circuit board 6 and the said board | substrate connection part 46a are connected by welding. As described above, since the notch 46b is provided in the board connecting portion 46a, it is possible to suppress a reactive current from flowing in the surface direction of the board connecting portion 46a during welding. In order to obtain the same effect, a hole may be provided instead of the notch 46b.
Further, the other electrode provided on the protection circuit board 6 and the other side surface of the battery 2 are connected, and the protection circuit board 6 is arranged to face the negative electrode projecting surface of the battery 2 to constitute a battery core. Will be.

In the battery core according to the present embodiment, since the PTC elements 41 and 42 are connected in advance by the common lead 46, the PTC elements 41 and 42 are connected in series with the negative terminals of the battery 2 and the battery 3. Therefore, it is only necessary to arrange the battery 2 and the battery 3 along the stepped portion, and the arrangement of the leads is simplified. That is, in this battery core, the lead for connecting the PTC elements 41 and 42 and the protection circuit board is only the common lead 46, and the length thereof is short, so that the energy density of the battery core is increased. Further, an insulating tape interposed between the leads is not necessary.
Accordingly, the number of members and the number of assembly steps can be reduced, and the cost can be reduced.
Further, since the number of welded portions is reduced, the reliability is improved.

In the first and second embodiments, the case where the PTC elements 41 and 42 are used as the protective elements has been described. However, the present invention is not limited to this, and a thermal fuse and a bimetal switch may be used. Good.
In the first and second embodiments, the case where the current limiting member 4 or 14 has two PTC elements has been described. However, the present invention is not limited to this.
In the first and second embodiments, the case where the batteries 2 and 3 are non-aqueous electrolyte secondary batteries is described. However, the present invention is not limited to this, and the nickel-hydrogen secondary battery and the nickel- Other batteries such as a cadmium secondary battery may be used.

Further, in the first and second embodiments, the case where the batteries 2 and 3 are connected in parallel has been described, but the present invention is not limited to this and may be connected in series.
Moreover, the electric element in which the current limiting member according to the present invention is arranged is not limited to a battery.

It is a partially broken perspective view which shows the battery core of the battery pack which concerns on Embodiment 1 of this invention. It is a partially broken top view which shows a battery core. It is a perspective view which shows a current limiting member. It is a perspective view which shows the electric current limiting member of the battery pack which concerns on Embodiment 2 of this invention. It is a partially broken top view which shows the battery core of the battery pack used as power supplies, such as PDA, used as the premise of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery core 2, 3 Battery 2a, 3a Negative electrode terminal 4, 14 Current limiting member 41, 42 PTC element 43, 46 Common lead 43a, 46a Board connection part 43b, 46b Notch 44, 45 Lead 5, 8 Insulation tape 6 Protection Circuit board 61 Board 62 Protection circuit 63 External output terminal 7 Lead 7a Electrode connection part

Claims (4)

When an excessive current flows through the electrical element, or when the temperature of the electrical element rises, the protective elements that limit the current of the electrical element are connected with an L-shaped or T-shaped common lead,
A current limiting member, wherein an extension portion of the common lead from a linear base portion is connected to an electric protection circuit.   The current limiting member according to claim 1, wherein a notch or a hole is provided on a connection side of the extension portion with the electrical protection circuit. A rectangular parallelepiped, two batteries arranged side by side,
The current limiting member according to claim 1 or 2,
And a protection circuit board on which an electrical protection circuit is mounted,
The battery pack is characterized in that the common lead of the current limiting member is disposed along the side surfaces adjacent to both the batteries, and the extension portion is connected to the electrical protection circuit.   The battery pack according to claim 3, wherein the two batteries are arranged side by side with a step in a direction intersecting with the direction of arrangement.

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