JP2007103284A - Lithium ion battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithium ion battery pack highly reliable and able to be efficiently assembled, wherein ultrasonic welding has no effect on a lithium ion battery and a protective circuit board. <P>SOLUTION: In this lithium ion battery pack in which a cell assembly 2 composed of the lithium ion battery 4 and the protective circuit board 5 are fixed by an upper case 1 and a lower case 3, fitting protrusions 111, 121 provided on the right and left sides 11, 12 of the upper case 1 or the lower case are engaged with fitting grooves 311, 312 provided on the right and left sides 31, 32 of the lower case 3 or the upper case, and fitting pawls 131, 141 provided on the end faces of the upper case 1 or the lower case are fitted with and locked to fitting holes 331, 341 provided on the end faces of the lower case 3 or the upper case. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a battery pack in which an assembly cell composed of a lithium ion battery and a protection circuit is fixed by an exterior case.

  In recent years, lithium ion batteries have been used as a power source for portable devices such as mobile phones and digital still cameras due to demands for higher capacity and smaller size. Mobile devices are required to be thin, and accordingly, lithium ion battery packs are also required to be designed to be small and thin.

  An exterior case that protects an assembly cell composed of a lithium ion battery and a protection circuit board is structurally separated into an upper case and a lower case. As a method for fixing the upper case and the lower case, ultrasonic welding is usually used.

  FIG. 4 is an exploded perspective view illustrating a conventional lithium ion battery pack. In the manufacture of the lithium ion battery pack, first, the assembly cell 2 in which the protective circuit board 5 is connected to the lithium ion battery 4 with the tab 6 is inserted into a predetermined position of the lower case 3. Thereafter, the upper case 1 is covered from above, and the fitting protrusions 113 and 123 provided on the right side surface 11 and the left side surface 12 of the upper case 1 are fitted into the fitting protrusions provided on the right side surface 31 and the left side surface 32 of the lower case 3. Ultrasonic welding provided on the rear end face 33 and the front end face 34 of the lower case 3 in the ultrasonic welding grooves 133 and 143 provided on the rear end face 13 and the front end face 14 of the upper case 1. The projections 333 and 343 are fitted and fixed by ultrasonic welding. Finally, the exterior label 7 was wound and fixed completely (see Patent Document 1).

  To reduce the thickness and size of the lithium ion battery pack, it is possible to reduce the clearance between the ultrasonic welding protrusions 333 and 343, the ultrasonic welding grooves 133 and 143, the protective circuit board 5, and the lithium ion battery 4. However, there is a risk that the energy of ultrasonic welding adversely affects the protective circuit board 5 and the lithium ion battery 4. That is, due to the ultrasonic welding energy, a crack or the like enters a connection portion inside the electronic component mounted on the protection circuit board, and the contact or open state is established. Or a crack etc. enter into the solder part which has joined the board and electronic parts, and it will be in a contact or an open state. Alternatively, the safety valve of the lithium ion battery may be opened, or the electrode may be peeled off, causing problems such as liquid leakage or performance degradation.

  FIG. 5 is a cross-sectional view illustrating an ultrasonic welding process of a conventional lithium ion battery pack. The clearance between the ultrasonic welding groove 133 provided on the rear end surface of the upper case and the ultrasonic welding protrusion 333 provided on the rear end surface of the lower case and the protective circuit board 5 is 0 mm or more, and is 0. Since the ultrasonic horn 8 is adjusted to a position that completely covers the ultrasonic wave so that the ultrasonic welding can be completed completely, the ultrasonic horn 8 covers the protective circuit board 5 and the ultrasonic welding is performed. There is a risk that the energy of the above will affect the protection circuit board 5.

JP 2005-1000068 A

  In the conventional lithium ion battery pack, the upper case and the lower case are ultrasonically welded, so the case side thickness is reduced by thinning and miniaturization, and the clearance between the protective circuit board and the lithium ion battery is small. As a result, the energy of ultrasonic welding affects the lithium ion battery and the protection circuit board.

  The present invention provides a lithium ion battery pack that can be assembled with high reliability and efficiency without affecting the lithium ion battery and the protection circuit board by ultrasonic welding.

  The battery pack of the present invention is a lithium ion battery pack in which an assembly cell composed of a lithium ion battery and a protection circuit board is fixed by an upper case and a lower case, and is provided for fitting on the left and right side surfaces of the upper case or the lower case. The protrusion and the fitting groove provided on the left and right side surfaces of the lower case or the upper case are fitted, and the fitting claw provided on the end surface of the upper case or the lower case and the end surface of the lower case or the upper case The provided fitting holes are fitted and locked.

  Further, in the battery pack of the present invention, the upper case and the lower case have an opening in a central portion excluding a rectangular outer frame, the assembly cell is arranged in the opening, and the upper case and the lower case The assembly cell can be covered with an exterior label.

  Furthermore, the battery pack of the present invention may have latch claws on the left and right side surfaces of the upper case or the lower case, and may have latch holes on the left and right side surfaces of the lower case or the upper case.

  According to the lithium ion battery pack of the present invention, the upper and lower cases are fixed by being fitted and locked with the fitting grooves and fitting protrusions on the side surfaces of the upper and lower cases and the fitting claws and fitting holes on the end surfaces, Since the welding operation is eliminated, the ultrasonic welding energy can avoid the influence on the lithium ion secondary battery and the protection circuit board. Further, there are no case burrs or the like generated during welding burrs or ultrasonic welding, and the appearance defect rate is reduced. Furthermore, there is no need for ultrasonic welding equipment, and there is an effect that it can be easily assembled.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is an exploded perspective view of a lithium ion battery pack according to the present invention, FIG. 2 is a perspective view illustrating a part of an assembly process of the lithium ion battery pack according to the present invention, and FIG. 3 is a lithium ion according to the present invention. It is sectional drawing of the case side fitting part of a battery pack.

  The production of the lithium ion battery pack will be described. First, an assembly cell 2 in which a protective circuit board 5 is connected by a tab 6 to a lithium ion battery 4 containing a battery element in a can made of an aluminum alloy having a width of 30.0 mm, a height of 48.0 mm, and a thickness of 4.0 mm, for example. Then, it is inserted into a predetermined position of the lower case 3 having an opening formed by injection molding a resin such as PC, PC / ABS having a width of 30.8 mm and a height of 48.8 mm. That is, the protection circuit board 5 is inserted along the rear end surface 33 of the lower case 3, and the assembly cell 2 is inserted along the right side surface 31, the left side surface 32, and the front end surface 34 of the lower case 3.

  After that, as shown in FIG. 2, the width is 30.8 mm made of the same resin as the lower case 3 and the height is 48.8 mm. The fitting protrusions 111 and 121 having a width of 1.0 mm of the provided protrusions are fitted from the rear end face 13 of the upper case 1 to the fitting grooves 311 and 321 provided with a concave cross section along the longitudinal direction of the left and right side surfaces of the lower case 3. It is inserted while being fitted to the front end face 34 of the case 3.

  Next, as shown in FIG. 3, the fitting protrusions 111 and 121 provided on the left and right side surfaces 11 and 12 of the upper case 1 and the fitting grooves 311 and 321 provided on the left and right side surfaces 31 and 32 of the lower case 3 are fitted. The upper case 1 is slid on the lower case 3 in the combined state. When sliding in a state in which the movement in the left-right direction is restricted, a total of three fitting claws provided at the upper part of the rear end face 13 and the lower part of the front end face 14 of the upper case 1, one at the center and one on the right and left, respectively. 131 and 141 are inserted into 0.4 × 1.0 mm fitting holes 331 and 341 provided on the rear end surface 33 and the front end surface 34 of the lower case 3 at positions corresponding to the fitting claws of the upper case, respectively. The movement in the direction is restricted, and the movement in the left and right front-rear direction is restricted and fixed. At that time, the latch claws 112 and 122 provided at the substantially central portions of the left and right side surfaces 11 and 12 of the upper case 1 are 0.42 × 1.02 mm provided at the corresponding positions of the left and right side surfaces 31 and 32 of the lower case 3, respectively. When inserted into the latch holes 312, 322, the movement in the front-rear direction is restricted even near the center of the side surface, and the upper case 1 and the lower case 3 are fixed more reliably.

  Here, the upper case 1 and the lower case 3 have openings, respectively, so that the thickness of the outer frame when the upper case 1 and the lower case 3 are fitted is the same as the thickness of the lithium ion battery 4. The thickness of the battery pack is suppressed. The assembly cell 2 is fixed by the outer frames of the upper and lower cases 1 and 3, and the assembly cell 2 is formed in the opening so that the side surface of the assembly cell 2 and the outer frames of the upper and lower cases 1 and 3 are located on the same plane. The side of the. Finally, the assembly cell 2 and the upper and lower cases 1 and 3 are covered with the exterior label 7 for the insulation of the product, the exterior display and the case fixation, and are completely fixed.

  Thereby, the lithium ion battery pack with the upper and lower cases fixed can be obtained without using ultrasonic welding. Although the embodiment using the latch claw and the latch hole has been described here, the upper and lower cases are fixed without the latch claw and the latch hole. By providing the latch claw and the latch hole, it can be fixed more securely and firmly.

  Further, the shape of the fitting protrusion, the fitting groove, the fitting claw, the fitting hole, the latch claw, the position and the quantity of the latch hole are examples, and the present invention is not limited thereto.

The disassembled perspective view of the lithium ion battery pack of this invention. The perspective view explaining a part of assembly process of the lithium ion battery pack of this invention. Sectional drawing of the case side fitting part of the lithium ion battery pack of this invention. The disassembled perspective view explaining the conventional lithium ion battery pack. Sectional drawing explaining the ultrasonic welding process of the conventional lithium ion battery pack.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper case 2 Assembly cell 3 Lower case 4 Lithium ion battery 5 Protection circuit board 6 Tab 7 Exterior label 8 Ultrasonic horn 11 (Upper case) Right side surface 12 (Upper case) Left side surface 13 (Upper case) Rear end surface 14 (Upper side) Case) Front end surface 31 (Lower case) Right side surface 32 (Lower case) Left side surface 33 (Lower case) Rear end surface 34 (Lower case) Front end surface 111 (Right side surface) Fitting 112 for projection (Right side surface) Latch claw 113 (Right side) Surface) fitting groove 121 (left side) fitting projection 122 (left side) latch claw 123 (left side) fitting groove 131 (rear end surface) fitting claw 133 (rear end surface) ultrasonic welding groove 141 (front end surface) ) Fitting claw 143 (front end surface) ultrasonic welding groove 311 (right side surface) fitting groove 312 (right side surface) latch hole 313 (right side surface) fitting projection 321 (left side surface) fitting groove 322 (left side surface) Luck Hatch hole 323 (left side) fitting projection 331 (rear end surface) fitting hole 333 (rear end surface) ultrasonic welding projection 341 (front end surface) fitting hole 343 (front end surface) ultrasonic welding projection

Claims (3)

  In a lithium ion battery pack in which an assembly cell composed of a lithium ion battery and a protective circuit board is fixed by an upper case and a lower case, a fitting protrusion provided on the left and right side surfaces of the upper case or the lower case, and the lower case or The fitting grooves provided on the left and right side surfaces of the upper case are fitted, and the fitting claws provided on the end surface of the upper case or the lower case and the fitting holes provided on the end surface of the lower case or the upper case are fitted. A lithium ion battery pack characterized by being locked.   The upper case and the lower case have an opening in a central portion excluding a rectangular outer frame, the assembly cell is arranged in the opening, and the upper case, the lower case, and the assembly cell are covered with an exterior label. The lithium ion battery pack according to claim 1.   3. The lithium ion battery pack according to claim 1, further comprising: latch claws on the left and right side surfaces of the upper case or the lower case, and latch holes on the left and right side surfaces of the lower case or the upper case.

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