Battery pack and fabricating method thereof

Disclosed are a battery pack and a fabricating method which can increase the coupling strength of a bare cell and a circuit accessory and prevent the circuit accessory from being separated from the bare cell due to external forces such as bending, twisting and falling of a battery, by forming a fixing member protruding from the upper part of the bare cell, and coupling the fixing member with a fixing member hole of the circuit accessory formed in advance by injection molding in the type of the fixing member being laid across the fixing member hole. The battery pack includes: a bare cell having a cap plate on the upper part of the bare cell; and a circuit accessory coupled with the upper part of the bare cell, wherein a fixing member is formed to protrude from the outer surface of the cap plate, a fixing member hole corresponding to the fixing member is formed on the circuit accessory, and the fixing member is inserted in and is coupled with the fixing member hole.

CLAIM OF PRIORITY

This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application earlier filled in the Korean Intellectual Property Office on 20 Nov. 2006 and there duly assigned Serial No. 10-2006-0114423.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a battery pack. More specifically, the present invention relates to a battery pack and a fabricating method thereof which can increase a coupling strength between a bare cell and a circuit accessory thus prevent the circuit accessory from being separated from the bare cell due to external forces like bending, twisting and falling of a battery, by forming a fixing member protruding from the upper part of the bare cell, and coupling the fixing member with a fixing member hole of the circuit accessory formed in advance by injection molding in the type of the fixing member being laid across the fixing member hole.

2. Description of the Related Art

Generally, a secondary battery is a battery capable of charging and discharging, differently from a primary battery which is not capable of charging. The secondary battery has been manufactured in the shape of a battery pack and broadly used as power supplies of portable electronic devices like a cellular phone, a notebook computer, a Personal Digital Assistant (PDA) and a camcorder.

Especially, a lithium secondary battery among the secondary batteries has high operating voltage and energy density per unit weight, thus is more suitable for potable electronic devices.

The general battery pack of the lithium secondary battery includes a bare cell capable of charging and discharging, a protection circuit board electrically coupled with the bare cell, the protection circuit board controlling charging and discharging and intercepting a circuit at the time of over charge and over discharge, and a resin molding formed as an external case by a hot melting method of filling hot melt resin in a gap between the bare cell and the protection circuit board to prevent the protection circuit board from being separated from the bare cell, to capably mount the battery pack on an external electronic device. The battery pack includes a separate holder for supporting the resin molding portion to prevent the resin molding portion from being separated from the bare cell by the external forces like bending, twisting and falling tests applied between the bare cell and the protection circuit module.

A conventional battery pack completed by resin molding uses resin of high temperature and high pressure to fill the small gap between the bare cell and the protection circuit board, and the resin of high temperature and high pressure might break down various electronic components of the protection circuit board.

Also, in the conventional battery pack completed by resin molding, an external terminal installed in the protection circuit module and electrically coupling the bare cell with the external electronic device is formed to be pad type in a flat shape. When said an external terminal of the conventional battery pack is coupled with a connection part formed in the external electronic device with surface contact, if an external shock such as falling is given to the battery, the surface contact between the external terminal of the battery pack and the connection part of the external electronic device can be cut off by the external shock. Accordingly, the instability of the electrical connection between the battery pack and the external electronic device becomes a problem.

When the pad-type external terminal of the conventional battery pack is coupled with the connection part of the external electronic device with pushing contacts, when the number of the pushing increases, a coating layer on the surface of the external terminal might peel off or crack. When such cracking of the coating layer of an external terminal of the battery pack gets serious, the electrical flow between the battery pack and the external electronic device might become out of order. Also, because the pad-type external terminal of the battery pack is disposed in the form of being exposed directly to the outside of the batter pack, it might be corroded by moisture in the air as a long period of time elapses.

Accordingly, a connector-type external terminal that is not exposed directly to the outside of the battery pack and is not coupled with the external electronic device with pushing contacts is needed. However, because the connector type external terminal has a complicated shape and a plurality of openings, it is difficult to apply the resin molding method of filling resin between the protection circuit module and the bare cell during the manufacture when the battery pack having a connector type external terminal.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide improved battery pack and improved process for manufacturing packs.

It is another object to provide a battery pack and a fabricating method thereof capable of increasing the coupling strength between a bare cell and a circuit accessory thus preventing the circuit accessory from being separated from the bare cell due to external forces like bending, twisting and falling of a battery, by forming a fixing member protruding from the upper part of the bare cell, and coupling the fixing member with a fixing member hole of the circuit accessory that is formed in advance by injection molding in the type of the fixing member being laid across the fixing member hole.

According to an aspect of the present invention, there is provided a battery pack, includes: a bare cell having a cap plate on the upper part thereof; and a circuit accessory coupled with the upper part of the bare cell, wherein a fixing member is formed to protrude from the outer surface of the cap plate, a fixing member hole corresponding to the fixing member is formed on the circuit accessory, and the fixing member is inserted in and is coupled with the fixing member hole.

The fixing member may be laid across and is coupled with the inner surface of the fixing member hole and the shape of the perpendicular section of the fixing member may be “T” shape.

The circuit accessory may be disposed on the upper part of the cap plate and is electrically coupled with the bare cell through a lead plate installed on the cap plate.

The circuit accessory may includes: a printed circuit board electrically coupled with the bare cell by the lead plate; an upper cover covering the printed circuit board, including the fixing member hole to couple with the bare cell by the fixing member; and an external terminal installed between the printed circuit board and the cover and electrically coupling the printed circuit board with an external electronic device.

The external terminal may be connector type.

The upper cover may include a principal plane having a shape and a size corresponding to those of the cap plate and a skirt bent and extended from the edge of the principal plane to the direction of the bare cell.

The fixing member hole may include an upper hole and a lower hole formed in a direction from the outer surface of the principal plane to the inside of the cover on a position perpendicularly corresponding to the fixing member, and the diameter of the upper hole is greater than the diameter of the lower hole to form a peripheral flange around stepped surface between the upper hole and the lower hole.

The fixing member may include a head portion being laid across the peripheral flange around stepped surface and a post portion disposed in the lower hole.

The battery pack of the present invention may further comprise a washer installed between the stepped surface and the head portion of the fixing member.

The outer diameter of the washer may be less than or equal to the diameter of the upper hole of the fixing member hole, and the inner diameter of the washer is greater than or equal to the diameter of the lower hole. The washer may be made of a stainless steel.

The diameter of the head portion may be greater than the diameter of the lower hole and is less than or equal to the diameter of the upper hole.

A concave recess whose perpendicular section has a polygonal shape may be formed on the upper surface of the head portion.

The fixing member may be formed integrally on the cap plate.

The cap plate may have a thickness twice to three times of that of the rest area in an area adjoining the area on which the fixing member is formed.

At least one weld hole may be formed on the skirt of the upper cover corresponding to electrical connection plates of the printed circuit board to weld the electrical connection plates formed on the printed circuit board to the lead plates of the bare cell.

The battery pack may further include a label such as a printed sheet adhered to the weld hole of the upper cover and adhered to enclose the side portion of the bare cell including the contact portion of the bare cell and the upper cover.

The lead plate of the bare cell may be inserted in a socket formed in the printed circuit board.

The battery pack of the present invention may include a stopper made of a material selected among rubber, glue and silicon may be installed to seal the fixing member hole.

According to another aspect of the present invention, a fabricating method is provided, which includes: preparing a bare cell on which a fixing member is installed; preparing a circuit accessory on which a fixing member hole corresponding to the fixing member is formed; inserting the fixing member in the fixing member hole, and physically coupling the circuit accessory with the bare cell by a spinning process or a punching process; and electrically coupling the bare cell with the circuit accessory.

The step of preparing a bare cell may include: forming a cap plate having the fixing members in the shape of protruding fixing members on outer surfaces of both side portions in a longitudinal direction of the cap plate on the upper part of the bare cell; and installing lead plates on the cap plate.

The fixing member may be formed by rolling the cap plate or is installed separately on the cap plate.

The protruding height of the fixing member protruded from the outer surface of the cap plate by a rolling process may be ½ to ⅔ of the thickness of the cap plate.

The step of preparing the circuit accessory may include: preparing a printed circuit board having electrical connection plates electrically coupled with the lead plates; preparing an upper cover covering the printed circuit board and including the fixing member hole; and installing an external terminal on the printed circuit board or the upper cover for electrical connection with the printed circuit board.

The step of preparing the upper cover may be to form by extruding a principal plane having a shape and a size corresponding to those of the cap plate and a skirt bent and extended from the edge of the principal plane to the direction of the bare cell; a fixing member hole disposed on the principal plane corresponding to the fixing member; and at least one weld hole on the skirt corresponding to the electrical connection plates of the printed circuit board.

The fixing member hole may include an upper hole and a lower hole formed in a direction from the outer surface of the principal plane to the inside of the upper cover on a position perpendicularly corresponding to the fixing member, and the diameter of the upper hole may be formed to be greater than the diameter of the lower hole to form a peripheral flange around stepped surface between the upper hole and the lower hole.

The height of the lower hole may be shorter than the protruding height of the fixing member to make the fixing member protrude above the stepped surface when the fixing member is inserted in the fixing member hole.

The step of inserting the fixing member in the fixing member hole, and coupling the circuit accessory and the bare cell may include: inserting the fixing members installed in the shape of protruding fixing members on both side portions in a longitudinal direction of the cap plate to protrude above the stepped surface of the fixing member hole of the upper cover; and forming the fixing member to be a head portion laid across the stepped surface and a fixing member portion disposed in the lower hole with the spinning or punching process. The step of coupling the circuit accessory and the bare cell may comprise inserting a washer on the fixing member before spinning or punching the fixing member.

The step of electrically coupling the bare cell and the circuit accessory may be welding the lead plates of the bare cell to the electrical connection plates of the printed circuit board through the weld hole of the upper cover.

The fabricating method of a battery pack of the present invention may further include: covering the fixing member hole with a stopper; and adhering a label to the side portion of the bare cell including the weld hole of the upper cover and the contact portion of the upper cover and the bare cell.

The step of preparing a circuit accessory may include: preparing a printed circuit board having a socket coupled with the lead plate; preparing an upper cover covering the printed circuit board and including the fixing member hole; and installing an external terminal between the printed circuit board and the cover.

The step of electrically coupling the bare cell and the circuit accessory may be inserting the lead plates of the bare cell in the sockets of the printed circuit board.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The aspects and features of the present invention and methods for achieving the aspects and features will be apparent by referring to the embodiments to be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed hereinafter, but can be implemented in diverse forms. The matters defined in the description, such as the detailed construction and elements, are nothing but specific details provided to assist those of ordinary skill in the art in a comprehensive understanding of the invention, and the present invention is only defined within the scope of the appended claims. In the entire description of the present invention, the same drawing reference numerals are used for the same elements across various figures.

Turning now to the drawings,FIGS. 1 through 4collectively,FIG. 1is a perspective diagram illustrating a completed battery pack according to one exemplary embodiment of the present invention,FIG. 2is a perspective diagram illustrating that the battery pack ofFIG. 1is disassembled,FIG. 3is a perspective diagram illustrating a bare cell before a circuit accessory is coupled thereto in the battery pack ofFIG. 2,FIG. 4is a perspective diagram illustrating a circuit accessory with the inside thereof facing upward in the battery pack ofFIG. 2,FIG. 5is a perspective diagram illustrating that a bare cell and a circuit accessory are coupled by covering the bare cell ofFIG. 3with the circuit accessory ofFIG. 4.

Referring toFIGS. 1 and 2, a battery pack400according to an embodiment of the present invention includes a bare cell100having a fixing member180, a circuit accessory200coupled with bare cell100, a lower cover320formed in the lower part of the bare cell100and a label360.

Bare cell100includes an electrode assembly (not shown) having a positive electrode, a negative electrode and a separator interposed between the positive electrode and the negative electrode; a can101receiving the electrode assembly and an electrolyte (not shown); and a cap assembly including a cap plate110closing the opening portion of can101.

Bare cell100includes a positive electrode terminal and a negative electrode terminal to supply charged power in the state of being electrically coupled with circuit accessory200through a positive electrode lead plate150and a negative electrode lead plate160. In the present invention, the positive electrode terminal can be cap plate110itself or a metal plate (not shown) coupled on cap plate110. A negative electrode terminal120is a terminal protruding perpendicularly from cap plate110, and is electrically insulated from cap plate110by an insulator gasket (not shown) interposed therebetween. Naturally, the polarity of cap plate110playing the role of the positive electrode terminal and negative electrode terminal120can be different according to exemplary embodiments.

Positive electrode lead plate150and negative electrode lead plate160electrically coupling bare cell100with circuit accessory200have a shape of “L” approximately, and are made of a conductive material, for example, nickel or nickel alloy. Such a positive electrode lead plate150, as illustrated inFIG. 3, is electrically coupled with the bare cell100, with one side thereof being coupled with cap plate110by a method such as welding.

And, to prevent a short circuit due to unnecessary connection between bare cell100and a printed circuit board210of circuit accessory200, an electrically insulating tape130is installed on the outer surface of the upper part of bare cell100, i.e., on the outer surface of the cap plate110. Electrically insulating tape130is made of an adhesive material in the same size as printed circuit board210of circuit accessory200.

Negative electrode lead plate160, as illustrated inFIG. 3, is electrically coupled with a current control unit such as a PTC (Positive Temperature Coefficient) device140whose one side is connected with negative electrode terminal120, and is electrically coupled with bare cell100. PTC device140prevents firing and explosion of the battery by short-circuiting an internal circuit thus prevents further current from flowing when the internal temperature of the battery rises, or the voltage of the battery rises due to over charge. Herein, PTC device140connected to one side of negative electrode lead plate160by a method such as welding is adhered and fixed to the upper part of cap plate110by electrically insulating tape130made of an adhesive material.

Battery pack400according to one exemplary embodiment of the present invention further includes fixing member180formed on the outer surface of cap plate110formed on the upper part of bare cell100.

Fixing members180are installed in the shape of fixing members protruding on both side portions in the longitudinal direction of cap plate110fixing member180is separately installed on the outer surface of cap plate110, or is formed in the structure of protruding to the outer surface by rolling cap plate110. Herein, the fixing member180can be made of the same material as cap plate110made of aluminum or aluminum alloy. The fixing member180fixes circuit accessory200to bare cell100and supports circuit accessory200against external forces to prevent circuit accessory200from being separated from bare cell100. Detailed explanation of the structure and the role of fixing member180will follow.

Referring toFIGS. 2 and 4, circuit accessory200is disposed on the upper part of the bare cell100, i.e., on the upper part of cap plate110, and includes a printed circuit board (PCB)210, an upper cover220and an external terminal216.

PCB210is a panel made of resin, on which a protection circuit (not shown) such as a circuit making the charging state uniform by controlling the charge and discharge of the battery, or a circuit preventing over discharge and over charge is formed. Although not shown in the drawing, circuit devices (not shown) are formed on PCB210to embody a charge-discharge circuit (not shown) and a protection circuit (not shown).

Electrical connection plates are installed on PBC210to electrically couple bare cell100and PCB210of the circuit accessory200. The electrical connection plates include a positive electrode connection plate212and a negative electrode connection plate214. Positive electrode connection plate212and negative electrode connection plate214installed in this manner are formed approximately in the shape of “L” for the electrical connection with the other side of positive electrode lead plate150and the other side of negative electrode lead plate160, respectively. Generally, lead plates150,160and electrical connection plates212,214are coupled by spot welding, respectively.

Upper cover220includes a principal plane222having a shape and a size corresponding to those of cap plate110, and a skirt224bent and extended from the edge of principal plane222to the direction of bare cell100. Such an upper cover covers and protects PCB210.

Upper cover220further includes a fixing member hole227on a position perpendicularly corresponding to fixing member180of bare cell100. Bare cell100and circuit accessory200are coupled by inserting fixing member180in and coupled with the fixing member hole227. The coupling of bare cell100and circuit accessory200will be explained in detail with reference toFIGS. 6 to 9b.

Also, upper cover220includes at least one weld hole226on skirt224corresponding to electrical connection plates212,214coupled with lead plates150,160of bare cell100for the electrical coupling of circuit accessory200including PCB210and bare cell100. Herein, weld hole226may have any shape selected among a circle and a polygon.

Negative electrode lead plate160and negative electrode connection plate214, and positive electrode lead plate150and positive electrode connection plate212can be coupled through weld hole226by resistance welding. Weld hole226is formed as one weld hole on skirt224corresponding negative electrode connection plate214inFIG. 2, and a weld hole is also formed on skirt224corresponding to negative electrode connection plate214in the opposite direction, and therefore serial type resistance welding can be used. And, a weld hole is formed on skirt224on one side corresponding to positive electrode connection plate212and positive electrode lead plate150as well, thus direct type resistance welding can be used. Herein, the reason that only one weld hole for the resistance welding of positive electrode lead plate150and positive electrode connection plate212respectively is that it is difficult to weld through two weld holes because external terminal216is disposed on the position on which positive electrode connection plate212is formed.

External terminal216is installed between PCB210and upper cover220and electrically couples PCB210with an external electronic device (not shown). Herein, external terminal216is formed to be connector type to let the electrical connection part (not shown) formed on the external electronic device (not shown) inserted therein, and can solve the problems of electrical connection (power off), and cracking and corrosion of a coating layer that occur in the existing pad type external terminal. External terminal216is installed on upper cover220that has been previously formed by injection molding, or on PCB210.

And, after bare cell100and circuit accessory200are coupled together, a stopper229for sealing fixing member hole227is installed. Such a stopper forms a part of the exterior of battery pack400. Herein, stopper229is made of any material selected among rubber, gluegun and silicon. Also, stopper229may be made of a polymer material having good adhesive property.

And, lower cover320is physically attached to the lower part of bare cell100, and such coupling is made by a strip or length of tape330with opposite major surfaces both coated with layers of an adhesive. Such a lower cover320protects against external shock like damage caused when the battery is accidentally dropped. Lower cover320that is attached to tape330serves as an electrical insulator.

Label sheet360encloses the circumferential surface of bare cell100finally, in the state of that upper cover220and lower cover320illustrated inFIG. 5are coupled with the upper part and lower part of bare cell100, respectively. Label360reinforces the coupling force of upper cover220and lower cover320, and reinforces the coupling force of the exteriors of upper cover220, lower cover320and bare cell100. Herein, label360is formed in the shape of covering the weld hole226of upper cover220, contact portion342of upper cover220and bare cell100and a contact portion344of lower cover320and bare cell100illustrated inFIG. 5, and is adhered to the circumferential surface of bare cell100.

Turning now to the drawings,FIGS. 6 through 9bcollectively,FIG. 6is an internal perspective view illustrating the upper part of the battery pack illustrated inFIG. 5,FIG. 7is a cross-sectional diagram of the fixing member ofFIG. 6,FIG. 8ais a cross-sectional diagram of another form of the fixing member illustrated inFIG. 7,FIG. 8bis a cross-sectional diagram of another form of the cap plate illustrated inFIG. 7,FIG. 9ais a perspective diagram illustrating that the fixing member ofFIG. 6is changed by a spinning or punching process,FIG. 9bis a cross-sectional diagram illustrating the fixing member ofFIG. 9a.

When looking into the coupling structure of bare cell100and circuit accessory200formed by coupling the PCB210and upper cover220, firstly, as illustrated inFIG. 6, fixing member180formed in the shape of a protruding fixing member on cap plate110of bare cell100is inserted in fixing member hole227of upper cover220.

Fixing member hole227is formed in a direction from the outer surface of principal plane222to the inside of upper cover220on a position perpendicularly corresponding to fixing member180formed on cap plate110of bare cell100, and includes an upper hole227aand a lower hole227b.

Diameter of upper hole227ais formed to be greater than the diameter of lower hole227bto form a peripheral flange around stepped surface228between upper hole227aand lower hole227b. Also, the height of lower hole227bis shorter than the protruding height of fixing member180to make fixing member180in the shape of a protruding fixing member above stepped surface228when fixing member180is inserted in fixing member hole227. In other word, fixing member180inserted in lower hole227bof fixing member hole227protrudes above stepped surface228.

Fixing members180are formed to protrude on both side portions in the longitudinal direction of cap plate110, and is formed to have a diameter smaller than or identical to that of lower hole227bthus are easily inserted in lower hole227bof fixing member hole227of the upper cover220. Herein, fixing member180in the shape of a fixing member is separately installed on cap plate110, or is formed by rolling cap plate110. The rolling process means making the cap plate be lengthen.

As illustrated inFIG. 7, when the fixing member is formed by rolling a cap plate110having a uniform thickness, the protruding height of fixing member180from the outer surface of cap plate110is formed to be ½ to ⅔ of the thickness of cap plate110which is, for example, 0.4 to 0.8 mm. If the protruding height of fixing member180is less than ½ of the thickness of cap plate110, then the protruding height of fixing member180is too short and thus fixing member180may not protrude sufficiently above stepped surface228separated from the outer surface of cap plate100when bare cell100is covered with upper cover220. Thus it may be difficult to perform a spinning or punching process to make fixing member180laid across stepped surface228of fixing member hole227to fix upper cover220to bare cell100. And, if the protruding height of fixing member180exceeds ⅔ of the thickness of cap plate110, then the thickness of cap plate110on which fixing member180is formed becomes too thin and cap plate110gets weak in terms of the strength. The spinning process means quickly turning things, and the punching process means hitting things hardly.

Fixing member180may be formed in a different shape, as illustrated inFIG. 8a. Referring toFIG. 8a, fixing member180aformed in a shape different from fixing member180ofFIG. 7is formed to have a concave recess in the upper surface. This makes the upper part of fixing member180aeasily spread on and be laid across stepped surface228of fixing member hole227when a spinning or punching process is performed on fixing member180ain the shape of a fixing member to fix circuit accessory200to bare cell100after fixing member180ahaving a concave recess is inserted in lower hole227bof fixing member hole227of upper cover220. That is, fixing member180ahaving a concave recess in the upper part has smaller internal density in the upper part than fixing member180that has no concave recess in the upper part, and thus the force pushing the upper part of fixing member180ais well transmitted to the edge portion of the concave recess during the spinning or punching process. Accordingly, the upper part of fixing member180acan be spread and be laid across stepped surface228of fixing member hole227better than the upper part of fixing member180illustrated inFIG. 7. Herein, the perpendicular section of the concave recess is a polygon, for example, an inverted triangle. However, the shape of polygon is not limited to an inverted triangle. And, the concave recess has only to be formed on the central part of the upper surface of fixing member180.

Also, a fixing member180billustrated inFIG. 8bcan be formed to protrude from the outer surface of a cap plate110by rolling cap plate110whose thickness is not uniform as a whole, differently from the cap plate illustrated inFIG. 7. That is, in cap plate110, the thickness of the area on which fixing member180bis formed is made to be thicker than that of the other area. This is because the part of the cap plate having a thin thickness can be transformed by the force generated by the rolling process at the time of the rolling process for making the fixing member protruded from the outer surface of the cap plate.

Herein, the thickness of the area of the cap plate110on which the fixing member180bis formed is formed to be between twice and three times of the thickness of the other area of the cap plate110. If the thickness of the area of the cap plate110on which fixing member180bis formed is less than twice of the thickness of the other area of cap plate110, it is not sufficient to prevent the deformation of cap plate110at the time of the rolling of cap plate110. And, if the thickness of the area of cap plate110on which fixing member180bis formed is more than three times of the thickness of the other area of cap plate110, the thickness of cap plate110becomes too thick and it is not easy to perform the rolling process of cap plate110to form fixing member180b.

InFIG. 8b, a concave recess (not shown) whose perpendicular section is an inverted triangle may be formed on the upper surface of fixing member180blike fixing member180aillustrated onFIG. 8a.

Then, fixing member180in the shape of a fixing member protruding above stepped surface228after passing through lower hole227bof fixing member hole227illustrated inFIG. 6is changed to have a T-shaped perpendicular section, i.e., to have the shape of having a head portion182and a post portion184by the spinning or punching process as illustrated inFIGS. 9aand9b.

Head portion182of fixing member180is laid across stepped surface228on the inner surface of fixing member hole227and post portion184is disposed in lower hole227band thereby fixing member180holds upper cover220including fixing member hole227. Herein, the diameter of head portion182is greater than the diameter of lower hole227b, and is less than or equal to the diameter of upper hole227ato be laid across stepped surface228on the inner surface of fixing member hole227.

Such “T” shaped fixing members180are formed on both side portions of the upper part of bare cell100, and couple circuit accessory200including upper cover220with bare cell100, and play the role of a support to prevent circuit accessory200from being separated from bare cell100by the external force. In one exemplary embodiment of the present invention, upper cover220may be firstly coupled with PCB210through the injection molding, and then PCB210is electrically connected with bare cell100; PCB210may be firstly electrically connected with bare cell100, then upper cover220is formed by injection molding.

Turning now to the drawings,FIGS. 10 through 12bcollectively,FIG. 10is a partial perspective diagram illustrating a fixing member inserted in a fixing member hole of an upper cover in a battery pack according to another exemplary embodiment of the present invention,FIG. 11ais a partial perspective diagram illustrating a washer inserted on the fixing member ofFIG. 10,FIG. 11bis a cross-sectional diagram illustrating the fixing member ofFIG. 11a,FIG. 12ais a perspective diagram illustrating the fixing member ofFIG. 11achanged by a spinning or punching process,FIG. 12bis a cross-sectional diagram illustrating the fixing member ofFIG. 12a.

When compared with the battery pack according to one embodiment of the present invention, the battery pack according to another exemplary embodiment of the present invention has the same constitutional elements except that an additional washer is installed on a fixing member inserted in a fixing member hole of an upper cover. Therefore, the same drawing reference numerals will be used for the same elements, and explanation on the same elements will be omitted. Therefore, in the battery pack according to another embodiment of the present invention, explanation will be focused on the washer.

Referring toFIGS. 10 to 11b, the battery pack according to another embodiment of the present invention further includes a washer340inserted on a fixing member180in the shape of a fixing member inserted in a fixing member hole227of an upper cover220.

As illustrated inFIG. 10, the outer diameter of washer340is less than or equal to the diameter of upper hole227aof fixing member hole227and the inner diameter of washer340is greater than or equal to the diameter of the lower hole227b. This is to insert washer340on fixing member180in the shape of a fixing member protruding above stepped surface228after passing lower hole227bof fixing member hole227, as illustrated inFIGS. 11aand11b.

Fixing member180in the shape of a fixing member on which washer340is inserted is changed to have a “T” shaped perpendicular section, i.e., to have the shape of having a head portion182and a post portion184by a spinning process or a punching process as illustrated inFIGS. 12aand12b. Head portion182of fixing member180is disposed in the structure of being laid across washer340and post portion184is disposed in lower hole227b, and thus fixing member180holds upper cover220including fixing member hole227. Here, the diameter of head portion182is greater than the diameter of lower hole227band less than or equal to the diameter of upper hole227ato be laid across a stepped surface228on the inner surface of fixing member hole227.

Washer340is made of a stainless steel. Accordingly, washer340having strength and is disposed on the coupling portion of the T-shaped fixing member180and the stepped surface228of fixing member hole227, and thereby makes the coupling strength stronger than in a case where the T shaped fixing member180is coupled on stepped surface228of fixing member hole227without a separate support member.

FIG. 13is a perspective diagram illustrating a separated battery pack according to still another exemplary embodiment of the present invention. When compared with the battery pack according to one embodiment of the present invention, the battery pack according to another exemplary embodiment of the present invention has the same constitutional elements except for the structure of the PCB of the circuit accessory. Therefore, the same drawing reference numerals will be used for the same elements, and explanation on the same elements will be omitted. Therefore, in the battery pack according to another embodiment of the present invention, explanation will be focused on the structure of the PCB electrically coupled with the bare cell.

The battery pack is formed by electrically coupling a PCB510of a circuit accessory500with a bare cell100firstly and make an upper cover520cover PCB510to be coupled with the bare cell100.

A circuit accessory500includes PCB510, an external terminal516and upper cover520.

PCB510includes sockets512,514instead of the electrical connection plates installed in the PCB210illustrated inFIG. 2. And, an external terminal516is installed on PCB510. The socket electrically couples PCB and the bare cell100. Specifically, an positive electrode lead plate150installed on bare cell100is electrically coupled by being inserted in the socket512, and a negative electrode lead plate160is electrically coupled by being inserted in the socket514. Sockets512,514may be formed in the shape of a hole or a groove to let lead plates150,160inserted therein. Herein, sockets512,514are installed in a portion of PCB510excluding the area where external terminal516is installed.

As shown above, the battery pack according to still another exemplary embodiment of the present invention electrically can couple bare cell100and PCB510more easily by inserting lead plates150,160in sockets512,514, than the battery pack according to one embodiment of the present invention which welds lead plates150,160to separate electrical connection plates212,214, thus can reduce the manufacturing cost for separate electrical connection plates212,214.

External terminal516can be installed on PCB510or on upper cover520including a principal plane522and a skirt524, as explained above, but is installed on PCB510in another embodiment of the present invention.

As shown above, fixing member180of bare cell100electrically coupled with PCB510is inserted in fixing member hole527of upper cover520. And fixing member180inserted in fixing member hole527is laid across the stepped surface (not shown) formed on the inner surface of fixing member hole527by a spinning or punching process. Accordingly, upper cover520and bare cell100are coupled. Then, fixing member hole527of upper cover520is sealed with a stopper529.

FIG. 14is a flow diagram illustrating a fabricating method of a battery pack according to the present invention.

Referring toFIG. 14, the fabrication method of a battery pack according to an exemplary embodiment of the present invention is as follows.

The battery pack according to the exemplary embodiment of the present invention includes a step of preparing a bare cell having a fixing member installed on the upper part thereof (S710), a step of preparing a circuit accessory having a fixing member hole formed thereon (S720), a step of assembling by physically combing the circuit accessory and the bare cell (S730) and a step of electrically coupling the bare cell and the circuit accessory (S740).

Referring toFIGS. 2 and 3, in the step of preparing a bare cell having a fixing member installed on the upper part thereof (S710), an electrode assembly (not illustrated) and an electrolyte (not shown) are received in the opening portion of a can101, and a fixing member180is installed on the upper part of the bare cell100formed by closing the opening portion of the can101with a cap plate110of the cap assembly.

Fixing members180are formed in the shape of protruding fixing members from the outer surface of both side portions in the longitudinal direction of cap plate110. Fixing members180are formed by rolling cap plate110or are separately installed on cap plate110. The protruding height of fixing member180protruded from outer surface of cap plate110by a rolling process is formed to be ½ to ⅔ of the thickness of cap plate110.

Referring toFIGS. 2 and 4, in the step of preparing a circuit accessory on which a fixing member hole is formed (S720), a PCB210including electrical connection plates212,214to be coupled with lead plates150,160installed on the bare cell is prepared. And, an upper cover220covering PCB210and including fixing member holes227is prepared. And, an external terminal216is installed on PCB210or upper cover220for the electrical connection with PCB210. Herein, external terminal216is installed on upper cover220to electrically couple with PCB210. Such an external terminal part216is formed to be connector type.

Upper cover220is prepared by extruding a principal plane222having a shape and a size corresponding to those of cap plate110and a skirt224bent and extended from the edge of principal plane222to the direction of bare cell100; disposing a fixing member hole227on principal plane222corresponding to fixing member180; and forming at least one weld hole226on skirt224corresponding to electrical connection plates212,214of PCB210all together.

Fixing member hole227of upper cover220includes an upper hole227aand a lower hole227bformed in a direction from the outer surface of principal plane222to the inside of upper cover220, and the diameter of upper hole227ais formed to be greater than the diameter of lower hole227bto form a stepped surface228between upper hole227aand lower hole227b. And, the height of lower hole227bis formed to be smaller than the protruding height of fixing member180to make the fixing member in the shape of a protruding fixing member above stepped surface228when fixing member180is inserted in fixing member hole227.

Referring toFIGS. 6 to 9b, in the step of physically coupling a circuit accessory and a bare cell (S730), fixing member180in the shape of a fixing member installed in the upper part of bare cell100is inserted to pass through lower hole227bof fixing member hole227of upper cover220and protrude above stepped surface228. And fixing member180is changed to have a head portion laid across stepped surface228and a post portion184disposed in lower hole227bby a spinning or punching process. In another embodiment of this invention, referring toFIGS. 10 to 12b, before fixing member180is transformed by spinning or punching, a washer340is inserted on fixing member180, and then the fixing member is transformed to be a head portion182laid across washer340and a post portion184disposed in lower hole227bby the spinning or punching process. Likewise, bare cell100and circuit accessory200can be fixed and coupled by letting fixing member180of bare cell100be laid across stepped surface228of circuit accessory200or washer340.

And, referring toFIGS. 2 and 5, in the step of electrically coupling a bare cell and a circuit accessory (S740), bare cell100and circuit accessory200are electrically coupled by welding lead plates150,160of the bare cell100and electrical connection plates212,214of PCB210included in circuit accessory200through weld hole226of upper cover220.

And, the battery pack is completed by covering and sealing fixing member hole227of upper cover220with a stopper, and adhering a label360to the side portion of the bare cell100, including weld hole226of upper cover220and contact portion342of upper cover220and bare cell110.

In another embodiment of this invention, referring toFIG. 12, in the step of preparing a circuit accessory (S720), electrical connection plates212,214coupled with lead plates150,160are removed and sockets512,514are formed on PCB510. Bare cell100and PCB510can be electrically coupled by simply inserting lead plates150,160of bare cell100in sockets512,514of PCB510included in circuit accessory500respectively.

External terminal216is electrically connected with cap plate110through positive electrode connection plate212and positive electrode lead plate150. Also, external terminal216is electrically connected with negative electrode terminal120through negative electrode connection plate214, negative electrode lead plate160and current control unit140. Here, the parts electrically connected with cap plate110and negative electrode terminal120in external terminal216are insulated from each other.

As described above, the battery pack and the fabricating method thereof according to the exemplary embodiment of the present invention firmly fixes and couples a circuit accessory on a bare cell and makes the circuit accessory be supported by the bare cell simultaneously and prevents the circuit accessory from being separated from the bare cell by external force like bending, twisting and falling of the battery, by forming a fixing member protruding on the upper part of the bare cell, and coupling the fixing member with a fixing member hole formed on an upper cover previously formed by injection molding in the type of the fixing member being laid across the fixing member hole.

Accordingly, the battery pack and the fabricating method thereof according to the exemplary embodiment of the present invention prevents electronic components from being damaged by resin of high temperature and high pressure when a bare cell and a protection circuit board are coupled by molding resin in a conventional battery pack, and does not need to separately install a holder in order to assure that a resin molding portion formed by resin molding as an external case will be supported by the bare cell. Therefore, increase of the entire fabricating cost due to a separate holder can be prevented.

Also, the battery pack and the fabricating method thereof according to the exemplary embodiment of the present invention prevents power off of electric flow and cracking and corrosion of an external terminal that occur when a conventional battery pack having a flat pad type external terminal is coupled with an external electronic device, by forming a connector-type external terminal for coupling electrically a bare cell, and coupling an upper cover previously formed by injection molding with the bare cell.

The present invention is not limited to a certain desirable embodiment as described above. It should be understood by those of ordinary skill in the art that various replacements, modifications and changes in the form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. Therefore, it is to be appreciated that the above described embodiments are for purposes of illustration only and are not to be construed as limitations of the invention.