Battery pack

The present disclosure discloses a battery pack suitable for improving cooling efficiency of a cooling duct for battery cells in a battery module by reducing a sealing area between a lower case and an upper case configured to fully surround the battery module. The battery pack according to the present disclosure includes a battery module including battery cells sequentially stacked and a cooling duct located on side of the battery cells; a lower case configured to load the battery module and the cooling duct therein; and an upper case coupled to the lower case so as to cover the battery module and the cooling duct, the upper case having a vent structure on the cooling duct. The vent structure has, on the cooling duct, an inner air passage unit opened at a sidewall of the upper case, and an outer air passage unit inserted into the inner air passage unit.

TECHNICAL FIELD

The present application claims priority to Korean Patent Application No. 10-2015-0085238 filed on Jun. 16, 2015 in the Republic of Korea, the disclosure of which is incorporated herein by reference.

The present disclosure relates to a battery pack suitable for improving cooling effects of an internal structure by flattening sealing surfaces of external structures to sufficiently surround the internal structure by using the external structures.

BACKGROUND ART

Recently, to reduce air pollution caused by exhaust gas of vehicles, the vehicles are being manufactured on the basis of research to ensure driving force by using an internal-combustion engine and/or an electric motor. Thus, the vehicles have evolved in the order of a hybrid vehicle, a plug-in hybrid vehicle, and an electric vehicle. In this case, the hybrid vehicle and the plug-in hybrid vehicle have an internal-combustion engine, an electric vehicle, and a battery pack, and the electric vehicle has an electric motor and a battery pack without an internal-combustion engine. In this case, the hybrid vehicle and the plug-in hybrid vehicle have an internal-combustion engine, an electric motor and a battery pack, and the electric vehicle has an electric motor and a battery pack without an internal-combustion engine.

In addition, the battery pack has also evolved with hybrid vehicles, plug-in hybrid vehicles, and electric vehicles. The battery pack is configured to be capable of being charged by power supplied from the outside of an electric vehicle or power produced in the electric vehicle. The battery pack has cooling ducts and a battery module between a lower case and an upper case. The cooling ducts introduce air from the outside to the inside of the battery pack so as to cool battery cells of the battery module using the air, and continuously discharge from the inside toward the outside of the battery pack.

Here, the cooling ducts are partially exposed to the outside air from an outer wall of the battery pack to suck air from the outside of the battery pack. Also, the upper case is curved according to shapes of the cooling ducts and closely attached to the lower case and the cooling ducts using a sealing member. However, if the cooling duct and the upper case are not matched, the cooling duct and the upper case have an unnecessary space between the cooling duct and the sealing member or between the sealing member and the upper case. The unnecessary space partially discharges the air to be introduced into the battery module via the cooling duct, thereby degrading the cooling performance of the cooling duct.

Accordingly, a shape of the cooling duct installed between the lower case and the upper case greatly affects cooling effects of battery cells per unit time. Many studies have been conducted on the shape of the cooling duct. One example of the studies has been disclosed in Korean Patent Laid-Open Publication No. 10-2012-0122000 (published on Nov. 7, 2012), entitled ‘Battery Pack with Inlet and Outlet Optimization Structure’. The battery pack has a cell module, an inlet duct, and an outlet duct in an outer case, and has an inlet cover and an outlet cover on an upper side of the outer case.

The inlet duct communicates with the inlet cover, and the outlet duct communicates with the outlet cover. Here, the inlet cover and the outlet cover are respectively located on different sides of the outer case. However, in the case of the battery pack, the outside air sequentially passes through the inlet cover, the inlet duct, the battery cells of the cell module, the outlet duct, and the outlet cover, so that battery cells located near the outlet cover may accumulate heat under the influence of hot air that has exchanged heat with other battery cells. The heat accumulation of some of the battery cells deteriorates electrical characteristics of the battery module.

DISCLOSURE

Technical Problem

The present disclosure is designed to solve the problems of the related art, and therefore the present disclosure is directed to providing a battery pack having a structure suitable for reducing a sealing area between a lower case and an upper case, which are sequentially stacked, and improving cooling efficiency of a cooling duct for battery cells of a battery module between the lower case and the upper case.

Technical Solution

In one aspect of the present disclosure, there is provided a battery pack including a battery module including battery cells sequentially stacked, air flow paths located between the battery cells, and a cooling duct located on side of the battery cells to define an air flow space configured to communicate with the air flow paths, the cooling duct having an air passing hole opened toward an upper portion of the battery module to communicate with the air flow space; a lower case configured to load the battery module and the cooling duct therein; and an upper case coupled to the lower case and configured to cover the battery module and the cooling duct, the upper case having a vent structure on the cooling duct. The vent structure includes an inner air passage unit configured to define an air passage and having a rectangular-tunnel-type window frame configured to communicate with the air passing hole through one side of the air passage and penetrate a sidewall of the upper case through the other side of the air passage, and an outer air passage unit inserted along an inner wall of the window frame, the outer air passage unit having through holes in a front wall located on a front side of the window frame and in a rear wall located on a rear side of the window frame.

According to the present disclosure, the lower case may have an end portion located at the same level along an upper edge thereof, and be closely attached to the upper case through a sealing member along the upper edge of the lower case.

According to the present disclosure, the battery pack further includes battery cartridges interposed between the battery cells. Each of the battery cartridges may include an outer frame; a lower cooling fin and an upper cooling fin fixed to an edge of the outer frame and spaced a predetermined distance apart from each other; and air induction tools located on both sides of the outer frame so as to expose an air flow path between the lower cooling fin and the upper cooling fin to the outside.

According to the present disclosure, the cooling duct opens toward the air induction tools of each of the battery cartridges through the air flow space.

The air passing, hole of the cooling duct may be lower than an uppermost level of the battery module.

In one aspect, the battery module may include a plurality of cooling ducts on both sides thereof, and the air passing holes of the respective cooling ducts may be located at the same level.

In another aspect, the cooling duct may be surrounded by the lower case and the upper case.

In another aspect, two cooling ducts may be located on each of both sides of the battery cells.

According to the present disclosure, at least one vent structure may be located at a sidewall of an edge of a long side of the upper case.

The inner air passage unit may surround the outer air passage unit.

In one aspect, the inner air passage unit may be tightly coupled to an edge of the air passing hole of the cooling duct through a sealing member.

In another aspect, the inner air passage unit may include the rectangular-tunnel-type window frame located at a sidewall of a housing of the upper case, a connection end configured to form a step from a front side to a rear side of the window frame on a lower side of the window frame, a strap-shaped latching protrusion protruding from an inner wall of the window frame along an inner edge of the window frame on the connection end, and a partition wall protruding from the housing toward the cooling duct on an opposite side of the connection end.

According to the present disclosure, the inner air passage unit may have flow-path connection units at an inner end portion of the connection end and an end portion of the partition wall in a lower portion of the housing of the upper case, and the flow-path connection units may be in contact with an edge of the air passing hole of the cooling duct.

The flow-path connection unit may have an inverted V-shaped groove structure at an end portion thereof.

In one aspect, each of the flow-path connection units may have a sealing member in the groove structure and be closely attached to the air passing hole through the sealing member.

Selectively, both sidewalls of the window frame may have fastening pieces protruding from the latching protrusion toward the partition wall at rear end portions thereof.

According to the present disclosure, on one side of the upper case, the outer air passage unit may allow the inflow of air through the front wall and through a downward bottom between the front wall and the rear wall and allow the outflow of air from the rear wall toward the inner air passage unit.

On the other side of the upper case, the outer air passage unit may allow the inflow of air from the inner air passage unit toward the rear wall and allow the outflow of air through the front wall and through the downward bottom between the front wall and the rear wall.

In one aspect, the outer air passage unit may have hooks, which protrude from the rear wall and are coupled to the fastening pieces of the inner air passage unit.

In another aspect, the outer air passage unit may have sidewalls between the front wall and the rear wall, and each of the sidewalls may protrude from a downward bottom under the front wall and the rear wall. The height of a protruding portion of each of the sidewalls may gradually decrease from the front wall toward the rear wall.

In another aspect, the downward bottom may have through holes.

Advantageous Effects

In a battery pack according to the present disclosure, a sealing member is located at the same level along the entire end portion of a lower case between the lower case and an upper case that are sequentially stacked, so that a sealing area between the lower case and the upper case may be small. Thus, the battery pack has no unnecessary space between the lower case and the sealing member or between the sealing member and the upper case.

The battery pack according to the present disclosure includes cooling ducts and a battery module between the lower case and the upper case and has no unnecessary space between an edge of the lower case and an edge of the upper case, thereby improving cooling efficiency of the cooling ducts included in the battery module.

The battery pack according to the present disclosure includes cooling ducts respectively located on both sides of the battery module between the lower case and the upper case and vent structures configured to respectively communicate with the cooling ducts in the upper case. Thus, the battery pack may rapidly introduce and discharge air into and from a plurality of regions of the upper case by using the vent structures and the cooling ducts, and cool battery cells of the battery module in a short amount of time.

Since the battery pack according to the present disclosure has a small sealing area between the lower case and the upper case and improves cooling efficiency of the cooling ducts for the battery module, an internal pressure between the lower case and the upper case, which is generated due to heat of the battery cells in the battery module, may be appropriately reduced during the driving of the battery module.

MODE FOR DISCLOSURE

In the embodiments described below, a battery cell refers to a lithium secondary battery. Here, the lithium secondary battery is collectively referred to as a secondary battery in which lithium ions act as working ions during charging and discharging to cause an electrochemical reaction between a positive electrode and a negative electrode. However, it should be clear that the present disclosure is not limited to the kind of batteries.

FIG. 1is an exploded perspective view of a battery pack according to an embodiment of the present disclosure.FIG. 2is a perspective view of the battery module ofFIG. 1.FIG. 3is a detailed perspective view of the battery cartridge ofFIG. 2.

Referring toFIGS. 1 to 3, a battery pack120according to the present disclosure includes a lower case5, a battery module50, and an upper case110. The lower case5opens toward the upper case110so as to accommodate the battery module50. In an aspect, the lower case5has an end portion located at the same level along an upper edge thereof.

The battery module50includes battery cartridges20having cooling flow paths and cooling ducts42,44,46, and48configured to introduce air into the cooling flow paths or discharge air from the cooling flow paths. The battery cartridges20are sequentially stacked in the battery module50. Two adjacent ones of the battery cartridges20may accommodate one or two battery cells (refer to C inFIG. 10) therebetween.

The cooling ducts42,44,46, and48are respectively located on the sides of the battery cartridges20. The cooling ducts42,44,46, and48may allow air to flow into the respective cooling flow paths of the battery cartridges20and cool, by the air, the battery cells C accommodated between the battery cartridges20. In an aspect, each of the cooling ducts46and48has a blowing fan (not shown).

When the blowing fan is driven, the blowing fan sucks air from the outside through the cooling ducts42,44so that air may flow into each of the cooling flow paths of the battery cartridges20. The air exchanges heat with the battery cells C accommodated between the battery cartridge20, flows from the cooling flow paths toward the cooling ducts46and48, and is discharged to the outside through the cooling ducts46and48.

The upper case110has an end portion that opens toward the lower case5and located at the same level along a lower edge thereof. The end portion of the upper case110faces the end portion of the lower case5. The upper case110includes vent structures102,104,106, and108in a box-shaped housing70that covers an upper portion of the battery module50.

The vent structures102,104,106, and108are located over the cooling ducts42,44,46, and48on a one-to-one basis. The vent structures102,104,106, and108are configured to guide the inflow of air from the outside to the inside of the upper case110or guide the outflow of air from the inside to the outside of the upper case110.

As shown inFIG. 2, the battery module50has cooling ducts42,44,46, and48that are tightly coupled to both side portions of the battery cartridges20. The cooling ducts42,44,46, and48are located between the lower case5and the battery cartridges20. Each of the cooling ducts42,44,46, and48has an air passing hole35that opens toward the upper case110.

The cooling ducts42,44,46, and48open toward side portions of the battery cartridges20under the air passing holes35. More specifically, the cooling ducts42,44,46, and48have grooves42a,44a,46a, and48athat open toward the side portions of the battery cartridges20under the air passing holes35. The grooves42a,44a,46a, and48ahave respective square edges and are attached to the battery cartridges20through sealing members interposed in the respective square edges.

The grooves42a,44a,46a, and48aprovide spaces for smooth flow of air introduced or discharged through the air passing holes35. The spaces communicate with the air passing holes35. The air passing holes35may be lower than an uppermost level of the battery module50. The air passing holes35of the cooling ducts42,44,46, and48may be located at the same level.

The battery cartridge20includes a lower cooling fin11and an upper cooling fin12as shown inFIG. 3. The lower cooling fin11and the upper cooling fin12are spaced apart from each other and fixed to an outer frame of the battery cartridge20by using an insert injection molding process. The battery cartridge20has air induction tools14,15,17, and18on sides thereof, which are covered by the cooling ducts42,44,46, and48in a lengthwise direction.

The air induction tools14,15,17, and18communicate with grooves42a,44a,46a, and48aof the cooling ducts42,44,46, and48. Each of the air induction tools14,15,17, and18has a slit-type opening in a lengthwise direction of the battery cartridge20. The slit-type opening serves as a passage through which air is introduced from each of the cooling ducts42,44,46, and48and discharged toward each of the cooling ducts42,44,46, and48.

The air induction tools14,15,17, and18expose an air flow path (not shown) located between the lower cooling fin11and the upper cooling fin12of the battery cartridge20to the outside of the battery cartridge20.

FIG. 4is a detailed exploded perspective view of a structure of the upper case ofFIG. 1.FIG. 5is a detailed partial cross-sectional view showing a coupling relationship between the lower case, the upper case, and the cooling duct ofFIG. 1.

Referring toFIGS. 4 and 5, the upper case110has a plurality of vent structures102,104,106, and108. The vent structures102,104,106, and108are located at an edge of a long side of the upper case110. The vent structure102has an inner air passage unit69aand an outer air passage unit95athat may be detachably attached to the inner air passage unit69a. The vent structure104has an inner air passage unit69band an outer air passage unit95bthat may be detachably attached to the inner air passage unit69b.

Similarly, the vent structure106has an inner air passage unit69cand an outer air passage unit95cthat may be detachably attached to the inner air passage unit69c. The vent structure108has an inner air passage unit69dand an outer air passage unit95dthat can be detachably attached to the inner air passage unit69d. The inner air passage unit69ahas a shape and a structure similar to those of the remaining inner air passage units69b.69c, and69d. However, when compared with the remaining inner air passage units69b,69c, and69d, the difference is only in size.

The outer air passage unit95chas a shape and a structure similar to those of the remaining outer air passage units95b,95c, and95d. However, when compared with the remaining outer air passage units95b,95c, and95d, the difference is only in size of the entire structure. Accordingly, for brevity, the vent structure102may be selected to collectively describe the remaining vent structures104,106, and108.

In the vent structure102, the inner air passage unit69aincludes a rectangular-tunnel-type window frame61located at a sidewall of the housing70of the upper case110. The inner air passage unit69aincludes a connection end63configured to form a step from a front side to a rear side of the window frame61on a lower side of the window frame61, a strap-shaped latching protrusion65protruding from an inner wall of the window frame61along an inner edge of the window frame61on the connection end63, and a partition wall68spaced apart from the connection end63and vertically protruding from an upper inner wall of the housing70toward the cooling duct42.

The inner air passage unit69ahas flow-path connection units66at an inner end portion of the connection end63and an end portion of the partition wall68, and the flow-path connection units66are in close contact with edges of the air passing holes35of the cooling duct42. Each of the flow-path connection units66has an inverted ‘U’-shaped groove structure and may have a sealing member in the groove structure. In one aspect, both sidewalls of the window frame61have fastening pieces67protruding from the latching protrusion65toward the partition wall68at rear end portions thereof.

In another aspect, the inner air passage unit69adefines a roughly “”-shaped air passage P1inside the housing70of the upper case110. In the vent structure102, the outer air passage unit95amay be aligned with the inner air passage unit69a. The outer air passage unit95amay couple hooks89, which protrude toward the inner air passage unit69a, to fastening pieces67so that the outer air passage unit95amay be coupled to the inner air passage unit69a.

FIG. 6is a detailed perspective view of a front wall of the outer air passage unit ofFIG. 4.FIG. 7is a detailed plan view of a downward bottom of the outer air passage unit ofFIG. 4.FIG. 8is a detailed perspective view of a rear wall of the outer air passage unit ofFIG. 4.

Referring toFIGS. 6 to 8, the outer air passage unit95ahas a hollow rectangular pillar shape. More specifically, the outer air passage unit95ahas through holes81located at an edge of a lower side of a front wall S1, through holes85located at a downward bottom S2between the front wall S1and a rear wall S3, through holes87located at an edge of an upper side of the rear wall S3, and hooks89protruding from the rear wall S3.

When the outer air passage unit95ais coupled to the inner air passage unit69aas shown inFIG. 5, the front wall S1is exposed to the air outside the inner air passage unit69a, the rear wall S3is located in the inner air passage unit69a, and the downward bottom S2is located toward a lower portion of the inner air passage unit69a.

The outer air passage unit95ahas sidewalls S4between the front wall S1and the rear wall S3. Each of the sidewalls S4protrudes from the downward bottom S2under the front wall S1and the rear wall S3, and the height of a protruding portion of each of the sidewalls S4gradually decreases from the front wall S1toward the rear wall S3. Here, the downward bottom S2and the protruding portions of the sidewalls S4form a space (refer to83inFIG. 6) under the downward bottom S2.

In one aspect, as shown inFIG. 5, the outer air passage unit95adefines a roughly “”-shaped air passage P2between the front wall S1and the rear wall S3. When the outer air passage unit95ais inserted into the inner air passage unit69aas shown inFIG. 5, the air passage P2of the outer air passage unit95acommunicates with the air passage P1of the inner air passage unit69ain the housing70of the upper case110.

FIG. 9is a perspective view of the battery pack ofFIG. 1, andFIG. 10is a partial cross-sectional view of the battery pack, which is taken along cutting lines I-I′ and II-II′ ofFIG. 9.

Referring toFIGS. 9 and 10, in the battery cartridge120, the lower case5is covered by the upper case110. Here, an upper edge of the lower case5is closely attached to a lower edge of the upper case110through a sealing member8. Also, the lower case5and the upper case110fully surround the cooling ducts42,44,46, and48of the battery module (refer to50inFIG. 1).

Referring toFIG. 10, the vent structures102,104,106, and108of the upper case110respectively communicate with the cooling ducts42,44,46, and48of the battery module50, For brevity, when one102of the vent structures102,104,106, and108is selected, an inner air passage unit69aof the vent structure102opens toward the cooling duct42in one direction D1and coupled to the air passing hole35of the cooling duct42, and opens toward a side portion of the housing70of the upper case110in another direction D2that is at a right angle to the one direction D1.

The vent structure102includes the inner air passage unit69a, which forms the air passage (refer to P1inFIG. 5) along an opening direction of the air passing hole35of the cooling duct42and perpendicular to the opening direction, and an outer air passage unit95a, which is inserted along an inner wall of the inner air passage unit69aand hooked to a fastening piece67through a hook89.

The inner air passage unit69ahas the flow-path connection units (refer to66inFIG. 5) at an inner end portion of the connection end63and an end portion of the partition wall68, and the flow-path connection units66are in close contact with edges of the air passing holes35of the cooling duct42. The inner air passage unit69asurrounds the outer air passage unit95a.

In one aspect, the inner air passage unit69adefines the air passage P1on the air passing hole35of the cooling duct42. The outer air passage unit95ais fitted in the window frame (refer to61inFIG. 4) of the inner air passage unit69aand engaged with the latching protrusion (refer to65inFIG. 4) on the connection end63of the window frame61. The hooks89of the outer air passage unit95aare coupled to the fastening pieces67of the inner air passage unit69a, respectively.

Next, a method of manufacturing a battery pack and an operation mechanism of the battery pack according to an embodiment of the present disclosure will be described with reference toFIGS. 1 and 10.

Referring toFIGS. 1 and 10, a lower case5, a battery module50, and an upper case110may be prepared. The lower case5may be formed as a box type and open toward the upper case110. Next, the battery module50may be accommodated in the lower case5and have battery cartridges20, battery cells C, and cooling ducts42,44,46, and48.

The battery cartridges20may be sequentially stacked. The battery cells C may be inserted between two adjacent battery cartridges20. The cooling ducts42,44,46, and48may be located at opposite sidewalls of the battery cartridges20. Subsequently, a sealing member8may be attached to the lower case5along an upper edge of the lower case5. The sealing member8may include bond, silicone, rubber, or urethane.

Thereafter, the upper case110may be closely attached to the sealing member8on the lower case5so as to cover the battery module50. In this case, in the upper case110, inner air passage units69a,69b,69c, and69dof vent structures102,104,106, and108may be coupled to air passing holes35of the cooling ducts42,44,46, and48through flow-path connection units66.

The air passing holes35may be attached to the flow-path connection units66by using a sealing member. Next, the outer air passage units95a,95b,95c, and95dare fitted along inner walls of the inner air passage units69a,69b,69c, and69d, the outer air passage units95a,95b,95c, and95dmay be naturally fitted on the connection ends63of the window frames (refer to61inFIG. 4) of the inner air passage units69a,69b,69c, and69d.

The hooks89of the outer air passage unit95a,95b,95c, and95dmay be hooked to the fastening pieces67of the inner air passage units69a,69b,69c, and69d, respectively. Thus, the lower case5, the battery module50, and the upper case110may constitute the battery pack120.

A cooling mechanism of the battery pack120will now be described. During the driving of a blowing fan (not shown) installed in the cooling duct46, on one side of the upper case110, the outer air passage unit95aof the battery pack120may allow the inflow of air through the through holes81of the front wall (refer to S1inFIG. 6) and through the through holes85of the downward bottom (refer to S2inFIG. 7) between the front wall S and the rear wall (refer to S3inFIG. 7), and allow the outflow of air from the through holes (refer to87inFIG. 8) of the rear wall S3toward the inner air passage unit69aalong flow lines F0and F1.

The outflowed air absorbs heat from the battery cells C while passing through the inside of an air flow path of the battery cartridge20through air induction tools14and15located on one side of each of the battery cartridges20. Thereafter, the outflowed air is discharged through air induction tools17and18located on the other side of each of the battery cartridges20.

In addition, during the driving of the blowing fan of the cooling duct46, on the other side of the upper case110, the outer air passage unit95cof the battery pack120may allow the inflow of air, which is heated while passing through the air flow path of each of the battery cartridges20through the through holes87of the rear wall S3from the air passage unit69c, and allow the outflow of air through the through holes81of the front wall S1and through the through holes85of the downward bottom S2between the front wall S1and the rear wall S3along flow lines F2and F3.

Accordingly, during the driving of the blowing fan of the cooling duct46, the battery pack120may allow air to flow from the outside toward the inside through the outer air passage unit95aand the inner air passage unit69aand pass through the air flow paths of the battery cartridges20. The air, which is heated through the air flow paths, may flow from the inside toward the outside through the inner air passage unit69cand the outer air passage unit95c.

While the present disclosure has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that it is capable of various changes and modifications without departing from the scope of the present disclosure as defined by the following claims.