JP4698344B2 - Assembled battery - Google Patents

Description

  The present invention relates to an assembled battery in which a large number of unit cells are connected in series or in parallel, and more particularly to an assembled battery used in a power supply device that mainly drives a motor that drives an automobile.

  An electric vehicle such as an electric vehicle or a hybrid car that is driven by both an internal combustion engine and a motor uses an assembled battery in which a number of unit cells are connected as a power source for supplying electric power to the driving motor.

  The assembled battery used for this type of application has a high output voltage to supply power to a high-power motor. For this reason, many unit cells are connected in series and stored in the holder. For example, an assembled battery mounted on a hybrid car currently on the market has hundreds of unit cells connected in series to increase the output voltage to several hundred volts. In this assembled battery, 5 to 6 unit cells are connected in series to form a battery module, and a large number of battery modules are housed in a holder case.

  An assembled battery mounted on an electric vehicle such as a hybrid car discharges a large current when the vehicle suddenly accelerates, accelerates the motor, and is charged with a large current by a regenerative brake when decelerating or going down a hill. . For this reason, the battery may become very hot. In addition, since the battery is used in a hot environment in summer, the battery temperature becomes even higher. Therefore, it is important for the assembled battery in which a large number of batteries are stored in the holder case to cool each of the built-in batteries efficiently and uniformly. Various adverse effects occur when there is a temperature difference between the batteries to be cooled. For example, a battery with a high temperature deteriorates and the actual charge capacity that can be fully charged is reduced. When batteries having a substantially reduced charge capacity are connected in series and charged and discharged with the same current, overcharge or overdischarge tends to occur. This is because the capacity that can be fully charged and the capacity that can be completely discharged are small. The characteristics of the battery are remarkably deteriorated due to overcharge and overdischarge. For this reason, a battery having a substantially reduced charge capacity deteriorates at an accelerated rate. In particular, when the temperature of the battery becomes high, the deterioration of the battery is further increased. For this reason, it is important for the assembled battery in which a large number of batteries are stored in the holder case to cool all the batteries uniformly so as not to cause temperature unevenness.

Various structures have been developed to achieve this. (See Patent Documents 1 to 5)
JP 11-329518 A JP-A-11-180168 JP 2001-167806 A JP 2001-256940 A JP 2002-141114 A

  In the assembled battery described in Patent Document 1, a plurality of battery modules are arranged in multiple stages on a holder case with a predetermined gap therebetween. In this assembled battery, a plurality of battery modules are arranged in a plurality of stages in a vertical orientation in a horizontal posture, and further arranged in a plurality of rows, and cooling air is forced between each row to cool the battery modules. Yes. In this cooling structure, the cooling efficiency of the battery module on the downstream side is lower than that on the upstream side. In order to eliminate this drawback, a turbulence promoting body such as a dummy battery unit is provided at the uppermost position of the holder case, and the battery module at the upstream position is arranged by disturbing the flow of cooling air introduced into the holder case. Cools efficiently. Further, the holder case is provided with an auxiliary cooling air intake for taking in the cooling air in the middle of the cooling air flow path, so that the battery cooling efficiency on the downstream side is enhanced.

  This assembled battery can improve the cooling effect of the battery module on the downstream side by turbulent flow or cooling air that flows in the middle. However, this structure does not allow all battery modules to be cooled to a uniform temperature. In particular, a large number of battery modules cannot be accommodated in the holder case to reduce the temperature difference between the battery modules.

  In the assembled battery of Patent Documents 2 and 3, a plurality of battery modules are integrated into a rectangular parallelepiped shape and accommodated in an outer case as a battery block. The battery block is disposed so as to be inclined with respect to the bottom surface and the top surface of the outer case. Inside the outer case, a cross-flow type impeller is rotatably disposed along the entire side portion close to the bottom surface of the battery block, and sucked from an intake port provided below the impeller. Cooling air flows into the space above the battery block, passes between the battery modules of the battery block, and cools each battery module. The cooling air is discharged from an exhaust port provided in the lower part of the battery housing case on the far side of the impeller.

  In this assembled battery, in order to blow cooling air uniformly between the battery modules, the supply side air duct is made narrower toward the downstream side, and the discharge side air duct is made wider on the downstream side. ing. In this structure, even if the battery modules can be stored in a single stage in the outer case and uniformly cooled, the battery modules can be stored in multiple stages in the outer case and not all battery modules can be cooled uniformly. In addition, a long sirocco fan is required to forcibly blow cooling air uniformly to all battery modules. In particular, when the number of battery modules stored in one stage increases, the sirocco fan becomes even longer. Although the sirocco fan has the feature that the operation sound can be made quieter, the structure is more complicated and the manufacturing cost is higher than that of the axial fan, and the efficiency of forced cooling air is low. For this reason, there is a drawback that the power consumption of the motor that drives the sirocco fan is increased.

  Further, the assembled batteries of Patent Documents 4 and 5 were previously developed by the present applicant. In this assembled battery, battery modules in which a plurality of batteries are connected in a rod shape are arranged in parallel and stored in a holder case. Further, a plurality of holder cases are arranged and stored in the outer case. Each holder case has a vent hole for cooling a plurality of battery modules housed therein. The ventilation opening is extended and opened in the direction parallel to the battery module. Furthermore, in order to cool the unit cell of a battery module uniformly, the ventilation hole is small at the end part of the holder case, and is greatly opened at the center part. This assembled battery can uniformly cool the unit cells of the elongated battery module. However, there is a drawback that the cooling efficiency of the battery module is low.

  Furthermore, the assembled battery described in these patent documents has a problem that the cooling of the battery module rapidly decreases when the forced air blowing is stopped. This is because if forced air blowing is stopped, the battery module is not cooled by the air flowing on the surface. In particular, an assembled battery that uniformly cools a large number of battery modules is provided with a battery module in a closed room without air leakage in order to control the flow of forced air to a specific state. The cooling of the battery module is significantly deteriorated in the state where the air blowing is stopped.

  The present invention has been developed for the purpose of solving such drawbacks. An important object of the present invention is to provide an assembled battery that can uniformly cool a plurality of battery modules housed in a holder case and can efficiently cool the battery modules even in a state where forced air blowing is stopped. .

The assembled battery of the present invention has the following configuration in order to achieve the above-described object.
The assembled battery has a plurality of battery modules 1 placed in a horizontal posture and arranged side by side so as to be adjacent to each other in a holder case 2, and cooling air is forced into the holder case 2 from below to above. Then, the cooling air is caused to flow in a direction crossing the battery module 1 to cool the battery module 1. Furthermore, the assembled battery is provided with a partition wall 3 extending vertically in the holder case 2, and a cooling air forced air duct 4 for cooling the battery module 1 is provided inside the partition wall 3. The forced air duct 4 inclines the partition 3 so that the width becomes narrower from the bottom to the top. Further, the holder case 2 is provided with a natural heat radiating duct 5 having an upper width wider than a lower width and an upper opening outside the inclined partition wall 3. In this assembled battery, the battery module 1 is cooled by both the forced air duct 4 and the natural heat radiating duct 5.

  In the assembled battery of the present invention, the battery module 1 has a structure in which a plurality of unit cells 10 are connected in a straight line, and each unit cell 10 has a part for a forced air duct 4 and another part for a natural heat radiating duct. 5 and can be cooled by the forced air duct 4 and the natural heat radiating duct 5.

  In the battery pack of the present invention, the partition wall 3 can be any one of a flat plate, a curved plate, and a stepped plate.

  In the assembled battery of the present invention, the battery module 1 can be housed in the holder case 2 in two or three stages.

  The assembled battery of the present invention is capable of uniformly cooling a plurality of battery modules housed in a holder case, and has an advantage that the battery modules can be efficiently cooled even in a state where forced air blowing is stopped. This is because the battery pack of the present invention is provided with a partition wall extending vertically in a holder case in which a plurality of battery modules are lined up and down, and a forced air duct that cools the battery module with cooling air inside the partition wall Is provided so that the width becomes narrower from the bottom to the top, and on the outside of the inclined partition wall, a natural heat radiating duct having an upper width wider than the lower width and opened upward is provided. This is because the battery module is cooled by both the forced air duct and the natural heat radiating duct. The assembled battery having this structure can forcibly blow the forced air duct and cool the battery module with the cooling air, and can also efficiently cool the battery module by dissipating heat from the natural heat radiating duct even when the forced air blowing is stopped.

  In particular, this battery pack has a forced air duct that narrows from the bottom to the top, and the forced air duct forcibly blows cooling air from the bottom to the top, so that the upper and lower battery modules are evenly cooled. it can. It is possible to increase the amount of heat exchange with cooling air that is high in temperature but flows at high speed by increasing the flow rate of the upper part where the width is narrower than that of the lower part and increasing the amount of heat exchange due to the flow rate of the cooling air at the upper part. This is because the upper battery module is cooled and the lower battery module is cooled by increasing the amount of heat exchange with cooling air having a low flow rate but low temperature.

  Furthermore, this battery pack uses a structure in which the width of the forced air duct is made narrower at the upper side than the lower side, so that a natural heat radiating duct can be provided between the forced air ducts, so that the space in the holder case is effectively used. It is possible to use both a forced air duct and a natural heat radiating duct. Moreover, the natural heat radiating duct is formed so that the upper width is wider than the lower width, contrary to the forced air duct, so that the upper battery module that tends to have a higher temperature is replaced with the lower battery module. Natural heat can be dissipated more efficiently than battery modules. In other words, the assembled battery of this structure makes good use of the structure that narrows the width of the forced air duct upward, widens the width of the natural heat dissipation duct, and reduces the temperature difference between the upper and lower battery modules. Natural heat dissipation.

  As described above, the battery pack according to the present invention has a unique structure of the forced air duct and the natural heat radiating duct, thereby stopping the forced air blowing while cooling the upper and lower battery modules uniformly with the forced air. Even in the state, it is possible to cool by ideally dissipating natural heat while reducing the temperature difference between the battery modules arranged above and below.

  Furthermore, since the assembled battery of the present invention cools the battery module by dissipating heat with the natural heat radiating duct even in a state where forced air blowing is stopped, in other words, the power required for forced air blowing is reduced while reducing the cooling amount by forced air blowing. It can be ideally cooled while saving running costs and running costs.

  Further, in the assembled battery according to claim 2 of the present invention, the battery module is constituted by a plurality of unit cells, and each unit cell is arranged in a forced air duct and the other part in a natural heat radiating duct. As a result, each unit cell can be efficiently cooled by both the forced air duct and the natural heat radiating duct. In this assembled battery, each unit cell is not cooled by either the forced air duct or the natural heat radiating duct, but is cooled by both the forced air duct and the natural heat radiating duct. That is, in the state where forced cooling air is forced, the portion disposed in the forced air duct is effectively cooled, and in the state where forced air blowing is stopped, the portion disposed in the natural heat radiating duct is efficiently cooled. Each unit cell can be efficiently cooled by both the forced air duct and the natural heat radiating duct.

  Embodiments of the present invention will be described below with reference to the drawings. However, the example shown below illustrates the assembled battery for embodying the technical idea of the present invention, and the present invention does not specify the assembled battery as follows.

  Further, in this specification, in order to facilitate understanding of the scope of claims, numbers corresponding to the members shown in the examples are indicated in the “claims” and “means for solving problems” sections. It is added to the members. However, the members shown in the claims are not limited to the members in the embodiments.

  In the assembled battery shown in FIG. 1, a plurality of holder cases 2 are connected horizontally side by side. The holder case 2 houses a plurality of battery modules 1. The battery module 1 includes a plurality of unit cells 10 connected in series and connected linearly. The plurality of battery modules 1 housed in each holder case 2 are connected to each other in series. However, the battery module in the holder case can be connected in series and in parallel.

  The assembled battery shown in the figure is provided with a cooling air duct 11 for forcibly sending cooling air to the holder case 2 below the holder case 2. The assembled battery is forcibly cooled by the cooling air duct 11 into the holder case 2 and forcibly cools a part of the battery module 1 in the holder case 2, and the other part of the battery module 1. Cool by releasing heat naturally.

  As shown in FIG. 1, an assembled battery in which a plurality of holder cases 2 are connected side by side can control the output voltage by changing the number of holder cases 2 to be connected. This is because the output voltage can be increased by increasing the number of holder cases 2 to be connected and increasing the number of batteries connected in series.

  In the assembled battery of FIG. 1, the cooling air duct 11 provided below the holder case 2 is gradually narrowed toward the flow direction of the cooling air. The cooling air duct 11 can uniformly cool the holder cases 2 by blowing cooling air uniformly.

  As shown in FIGS. 2 to 6, the holder case 2 accommodates a plurality of battery modules 1 in a horizontal posture so as to be adjacent to each other vertically. The battery module 1 has a plurality of unit cells 10 connected in a straight line in series. In the battery module 1, for example, 5 to 6 unit cells 10 are linearly connected. However, the battery module can connect four or less, or seven or more unit cells. The unit cell 10 is a nickel metal hydride battery. However, the unit cell may be another secondary battery such as a lithium ion secondary battery or a nickel cadmium battery. In the illustrated battery module 1, cylindrical batteries are linearly connected to form a columnar shape, but the battery module may be formed in a polygonal column shape such as a square column.

  The holder case 2 shown in the figure stores battery modules 1 in two rows and two stages, and stores four battery modules 1. However, the assembled battery of the present invention does not specify the number of battery modules and the number of stages stored in the holder case as shown in the figure. This is because the holder case can store battery modules in three or more stages, or can store battery modules in three or more rows.

  The holder case 2 shown in the figure has a closed box shape that houses the battery module 1 therein, and forcibly blows cooling air from below to above. The cooling air flows in a direction intersecting the battery module 1 to cool the battery module 1. In order to blow the cooling air in this direction, the holder case 2 has an inlet 6 for the cooling air opened on the bottom plate 2a and an outlet 7 opened on the top plate 2b.

  The holder case 2 is provided with a plurality of partition walls 3 extending vertically inside, and the inside of the partition wall 3 is a forced air duct 4 and the outside is a natural heat radiating duct 5. The forced air duct 4 is a duct that forcibly blows cooling air that cools the battery module 1. The natural heat radiating duct 5 is a duct that cools the battery module 1 by naturally radiating heat without forcibly blowing cooling air.

  The holder case 2 shown in the figure is provided with six partition walls 3 and partitions the inside of the holder case 2 into four forced air ducts 4 and three natural heat radiating ducts 5. Further, in the illustrated holder case 2, two forced air ducts 4 provided in the middle are provided between the opposing partition walls 3, and the outermost forced air duct 4 is disposed between the partition wall 3 and the end plate 2 c of the holder case 2. Between.

  The holder case 2 in FIG. 2 is divided into three parts: an intermediate case 2B and a side case 2A connected to both sides of the intermediate case 2B. The intermediate case 2B and the side case 2A are made of plastic, and the partition wall 3 is integrally formed. The holder case 2 is arranged in a fixed position by sandwiching the battery module 1 from both sides with a partition wall 3. The partition wall 3 is provided with a fitting recess 3 </ b> A along the outer shape of the battery module 1. The intermediate case 2B is provided with two fitting recesses 3A on both side edges of the partition wall 3, and the side case 2A is provided with two fitting recesses 3A on the inner edge. The battery module 1 is guided by the fitting recess 3 </ b> A, is sandwiched between the partition walls 3 of the intermediate case 2 </ b> B and the side case 2 </ b> A, and is held at a fixed position of the holder case 2. The fitting recess 3 </ b> A holds the battery module 1 by bringing the inner peripheral edge into contact with the surface of the battery module 1.

  The partition wall 3 of the holder case 2 is provided so as to be inclined so that the width of the forced air duct 4 becomes narrower from the bottom to the top so as to uniformly cool the upper and lower battery modules 1. The partition wall 3 shown in the figure is a flat plate, and the width of the forced air duct 4 is linearly narrowed from the bottom to the top. However, the partition wall can be a curved plate or a stepped plate.

  The forced air duct 4 has an upper flow velocity that is narrower than that of the lower portion, so that the amount of heat exchange by the flow velocity of the cooling air is increased at the upper portion. The cooling air blown to the forced air duct 4 cools the battery module 1 and gradually increases in temperature. For this reason, the temperature of the cooling air is higher in the state of cooling the upper battery module 1 than in the state of cooling the lower battery module 1. The cooling air having a high temperature reduces the temperature difference with the battery module 1 and reduces the amount of heat exchange. Therefore, in the upper battery module 1, the temperature of the cooling air is increased and the amount of heat exchange caused by the temperature is reduced. In order to eliminate this problem, the width of the forced air duct 4 is narrowed at the top, the flow rate of the cooling air is increased, and the heat exchange amount is increased. That is, the upper battery module 1 increases the heat exchange amount with the cooling air that is high in temperature but flows at high speed, and the lower battery module 1 increases the heat exchange amount with the cooling air that has a low flow rate but low temperature, The upper and lower battery modules 1 are uniformly cooled.

  In the assembled battery of the present invention, a part of the battery module 1 is cooled by the forced air duct 4 and the remaining part is cooled by the natural heat radiating duct 5. The forced air duct 4 cools the battery module 1 in a state where the cooling air is forcedly blown. The natural heat radiating duct 5 cools the battery module 1 not only in a state where forced cooling air is blown but also in a state where forced cooling air is not blown.

  Furthermore, the assembled battery of the present invention is provided with the natural heat radiating duct 5 by skillfully utilizing the structure in which the width of the forced air duct 4 is narrower at the upper side than at the lower side. Moreover, the structure which arrange | positions the battery module 1 in multiple stages up and down has the tendency for the temperature of the battery module 1 of an upper stage to become high. This is because the temperature of the air that cools the upper battery module 1 increases because the air is heated and rises. The assembled battery of the present invention uses the structure in which the width of the forced air duct 4 is narrowed upward, so that the upper battery module 1 efficiently dissipates heat more efficiently than the lower battery.

  In order to realize this, the natural heat radiating duct 5 of the assembled battery shown in the figure has an upper width that is wider than a lower width and opens upward. Since the partition wall 3 is inclined so as to provide a forced air duct 4 that makes the upper width narrower than the lower side, the natural heat radiating duct 5 provided outside the partition wall 3 has an upper width wider than the lower side. Become. This structure cools the upper battery module 1 more efficiently than the lower battery module 1, and effectively prevents the temperature of the upper battery module 1 from increasing. In particular, since the natural heat radiating duct 5 naturally cools the battery module 1 to cool it, the battery module 1 is efficiently cooled while reducing the temperature difference even when the cooling air is not forced to the forced air duct 4. .

  The holder case 2 connects the forced air duct 4 to the cooling air duct 11 through an inlet 6 that opens to the bottom plate 2a. The cooling air blown from the cooling air duct 11 is sent to the forced air duct 4 in the holder case 2 through the inlet. The cooling air passing through the forced air duct 4 cools a part of the battery module 1 and is exhausted to the outside from the discharge port 7 provided on the top plate 2 b of the holder case 2.

  The top plate 2 b of the holder case 2 is provided with an opening 8 that opens above the natural heat radiating duct 5. The opening 8 of the natural heat radiating duct 5 opens substantially the entire upper end of the natural heat radiating duct 5 in order to increase the natural heat radiating.

  The assembled battery in the figure cools each unit cell 10 constituting the battery module 1 by both the forced air duct 4 and the natural heat radiating duct 5. In other words, the unit cell 10 is not cooled by either the forced air duct 4 or the natural heat radiating duct 5. In order to cool each unit cell 10 with both the forced air duct 4 and the natural heat radiating duct 5, the holder case 2 in the figure sandwiches the middle of the outer can of the unit cell 10 with the partition wall 3. In the unit cell 10 in which the partition wall 3 is disposed in the middle of the outer can, the outer can inside the partition wall 3 is disposed in the forced air duct 4 and the outer can outside the partition wall 3 is disposed in the natural heat radiating duct 5. To do.

  The outer can of the unit cell 10 cooled by both the forced air duct 4 and the natural heat radiating duct 5 effectively cools the portion disposed in the forced air duct 4 in a state where the cooling air is forcibly blown. In the state where forced cooling air is stopped, the portion disposed in the natural heat radiating duct 5 is efficiently cooled. This cooling state changes the portion of the outer can that is efficiently cooled when the forced cooling air is blown and when the forced cooling is stopped. The local cooling of the outer can causes a temperature difference in the outer can. However, the excellent heat conduction of the outer can reduces the temperature difference of the outer can. For this reason, even if a part of the unit cell 10 is cooled by the forced air duct 4 and the other part is cooled by the natural heat radiating duct 5, a temperature difference that adversely affects the unit cell 10 does not occur.

  Further, in the assembled battery shown in FIGS. 2 and 6, end plates 12 positioned at both ends of the battery module 1 are fixed to the holder case 2. The end plate 12 is formed of an insulating material such as plastic. The end plate 12 opens electrode windows 15 for exposing the output terminals 14 provided at both ends of the battery module 1. The assembled battery has a bus bar 13 fixed to an output terminal 14 of the battery module 1 exposed from the electrode window 15 of the end plate 12. The bus bar 13 is a metal plate that connects adjacent battery modules 1 in series or in parallel. The bus bar 13 is screwed and fixed to the output terminal 14 of the battery module 1, and is fixed to a fixed position of the end plate 12. The end plate 12 shown in the drawing is integrally formed with insulating ribs 16 disposed between the bus bars 13, and the insulating ribs 16 prevent the adjacent bus bars 13 from contacting each other.

It is a schematic sectional drawing of the assembled battery concerning one Example of this invention. It is a disassembled perspective view of the assembled battery concerning one Example of this invention. It is a perspective view which shows the internal structure of the holder case of the assembled battery shown in FIG. FIG. 4 is a cross-sectional view of the holder case shown in FIG. 3 taken along line AA. It is a BB sectional view of the holder case shown in FIG. It is a bottom perspective view of an assembled battery according to an embodiment of the present invention.

Explanation of symbols

1 ... battery module 2 ... holder case 2A ... side case
2B ... Intermediate case
2a ... Bottom plate
2b ... top plate
2c ... End plate 3 ... Bulkhead 3A ... Insertion recess 4 ... Forced air duct 5 ... Natural heat radiating duct 6 ... Inlet 7 ... Discharge port 8 ... Opening 10 ... Unit cell 11 ... Cooling air duct 12 ... End plate 13 ... Bus bar 14 ... Output terminal 15 ... Electrode window 16 ... Insulating rib

Claims (4)

A plurality of battery modules (1) are placed in a horizontal posture and are arranged side by side so as to be adjacent to each other in the holder case (2). The battery pack is configured to cool the battery module (1) by forcibly blowing air and flowing cooling air in a direction intersecting the battery module (1),
A partition wall (3) extending vertically is provided in the holder case (2), and a forced air duct (4) for cooling air to cool the battery module (1) is provided inside the partition wall (3). The partition wall (3) is inclined so that the width of the duct (4) becomes narrower from the bottom to the top, and the upper width is wider than the lower width outside the inclined partition wall (3). In addition, a natural heat radiating duct (5) with an upper opening is provided,
An assembled battery in which the battery module (1) is cooled by both the forced air duct (4) and the natural heat radiating duct (5).   A battery module (1) connects a plurality of unit cells (10) in a straight line, and each unit cell (10) is partly forced air duct (4) and the other part is natural heat dissipation duct. The assembled battery according to claim 1, wherein the battery pack is disposed in (5) and is cooled by a forced air duct (4) and a natural heat radiating duct (5).   The assembled battery according to claim 1, wherein the partition wall (3) is one of a flat plate, a curved plate, and a stepped plate. The assembled battery according to claim 1, wherein the battery module (1) is housed in two or three stages in the holder case (2).

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