JP2010211963A - Power storage apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device capable of efficiently radiating heat of a power storage element with a simple configuration.
A power storage device (1) is in contact with a plurality of power storage elements (21), a case (10) for accommodating a plurality of power storage elements in a sealed state, and an outer surface of the power storage element, and heat from the power storage elements. And an absorbent sheet (23) that absorbs the liquid refrigerant that can be received and evaporated. The absorbent sheet can absorb the refrigerant (40) filled in the case into the absorbent sheet by using a capillary phenomenon.
[Selection] Figure 1

Description

  The present invention relates to a power storage device having a structure that allows heat dissipation of a power storage element.

  In the battery cooling structure described in Patent Document 1, a refrigerant (liquid) is brought into contact with a single cell, and when the single cell generates heat, the single cell is cooled by evaporating the refrigerant. And the vapor | steam of a refrigerant | coolant is liquefied by being cooled with a condenser, and returns to the space in which the cell was accommodated.

  On the other hand, in the collective battery described in Patent Document 2, by disposing a heat insulating member formed of resin between two adjacent unit cells, the heat generated in one unit cell can be reduced. The transmission to the unit cell is suppressed. Moreover, the channel | path (space) for moving the air used for cooling of a cell is formed by forming a groove | channel in a heat insulation member.

JP-A-11-135160 (paragraphs 0043-0045, FIG. 1) JP 2004-362879 (paragraphs 0010, 0013, FIG. 1)

  In the battery cooling structure described in Patent Document 1, since the refrigerant is brought into contact with the entire surface of the unit cell, the amount of refrigerant used increases. In particular, when an expensive refrigerant is used, the cost of the cooling structure is increased.

  On the other hand, in the configuration described in Patent Document 2, the unit cell can efficiently dissipate heat in the passage formed by the groove of the heat insulating member. However, the portion of the heat insulating member where the groove is not formed is in contact with the unit cell, and a space for releasing heat generated in the unit cell is not formed. For this reason, in the area | region where a cell and a heat insulation member are mutually contacting, there exists a possibility that heat dissipation of a cell cannot be performed efficiently.

  Accordingly, an object of the present invention is to provide a power storage device that can efficiently dissipate heat from a power storage element with a simple configuration.

  A power storage device according to the present invention includes a plurality of power storage elements, a case that houses the plurality of power storage elements in a sealed state, and a liquid refrigerant that contacts the outer surface of the power storage element and can evaporate by receiving heat from the power storage element. And an absorbent sheet that has been absorbed.

  Here, the absorption sheet can absorb the refrigerant filled in the case into the absorption sheet by using a capillary phenomenon. The absorbent sheet only needs to have a structure capable of generating capillary action. Specifically, the absorbent sheet can be formed of a porous body. Moreover, if an absorption sheet is formed with a fiber, a capillary phenomenon can be generated in an absorption sheet or it can manufacture at low cost.

  The plurality of power storage elements can be arranged side by side in a predetermined direction with the absorbent sheet and the spacer interposed therebetween. Here, an absorption sheet and a spacer are arranged side by side in a predetermined direction between two power storage elements arranged adjacent to each other. The spacer is in contact with the surface of the absorbent sheet opposite to the contact surface with the power storage element in a predetermined direction. Moreover, the spacer forms a space for moving the vapor of the refrigerant from the absorbent sheet toward the case side on the contact surface with the absorbent sheet. Here, the space can be formed by providing the spacer with a plurality of protrusions extending in a substantially vertical direction.

  In a configuration in which a plurality of power storage elements are arranged in a predetermined direction, the absorbent sheet can be formed in a shape along the outer shape of the power storage element when viewed from the predetermined direction. In addition, it is possible to provide a restraining structure that applies a restraining force for bringing adjacent power storage elements close to each other in a predetermined direction to a plurality of power storage elements. Thereby, an absorption sheet can be closely_contact | adhered to an electrical storage element, the heat which generate | occur | produced in the electrical storage element can be easily transmitted to an absorption sheet, and the refrigerant | coolant in an absorption sheet can be evaporated easily. Here, the restraining force can be generated using a case that houses the power storage element, or a dedicated member for generating the restraining force can be provided.

  On the top surface of the case, a heat radiation fin that protrudes from the outer wall surface of the case toward the outside of the case and contacts the cooling medium supplied from the outside of the power storage device can be provided. Thereby, a case can be cooled via a radiation fin, and the vapor | steam of the refrigerant | coolant which evaporated from the absorption sheet can be liquefied by carrying out heat exchange between cases. That is, the refrigerant vapor can be liquefied and absorbed again by the absorbent sheet.

  In the present invention, when the electricity storage element generates heat due to charging / discharging or the like, the heat in the absorbent sheet can be evaporated by this heat. Then, heat from the power storage element can be absorbed by the heat of vaporization of the refrigerant, and an increase in temperature of the power storage element can be suppressed. Moreover, since the refrigerant | coolant was only absorbed by the absorption sheet, the quantity of a refrigerant | coolant can be reduced.

It is a longitudinal cross-sectional view which shows the internal structure of the battery pack which is Example 1 of this invention. 3 is a cross-sectional view illustrating an internal configuration of a battery pack that is Embodiment 1. FIG. In Example 1, it is a figure explaining the heat dissipation process of a cell. FIG. 6 is a diagram illustrating a partial configuration of a battery module that is a modification of the first embodiment. In another modification of Example 1, it is an external view of a cylindrical cell. It is a side view which shows the structure provided with two or more cylindrical cell.

  Examples of the present invention will be described below.

  A battery pack (power storage device) that is Embodiment 1 of the present invention will be described with reference to FIGS. 1 and 2. Here, FIG. 1 is a longitudinal sectional view showing the internal configuration of the battery pack, and FIG. 2 is a transverse sectional view showing the internal configuration of the battery pack. 1 and 2, an X axis, a Y axis, and a Z axis are axes orthogonal to each other, and the Z axis is an axis corresponding to the vertical direction.

  The battery pack 1 of the present embodiment is mounted on a vehicle, and examples of the vehicle include a hybrid vehicle and an electric vehicle. A hybrid vehicle is a vehicle provided with an internal combustion engine or a fuel cell in addition to the battery pack 1 as a power source for running the vehicle. An electric vehicle is a vehicle that uses only the battery pack 1 as a power source of the vehicle. If the battery pack 1 is used, the kinetic energy generated when the vehicle is braked can be stored as regenerative power, or the power supplied from the outside of the vehicle can be stored.

  The battery pack 1 includes a pack case 10 and a battery module 20 accommodated in the pack case 10. The inside of the pack case 10 is hermetically sealed. Further, on the upper surface of the pack case 10, a plurality of radiating fins 11 protruding toward the outside of the pack case 10 are provided. Each radiation fin 11 extends in the X direction, and the plurality of radiation fins 11 are arranged side by side in the Y direction.

  The air supplied from the fan 50 comes into contact with the radiating fins 11. Specifically, a part of the duct connected to the fan 50 is arranged along the upper surface of the pack case 10, and the radiating fins 11 are located inside the duct. Thereby, the air from the fan 50 can be made to contact the radiation fin 11 efficiently. As the air supplied to the radiating fins 11, for example, air in the passenger compartment can be used. The passenger compartment is a space where passengers get on.

  In the present embodiment, air is brought into contact with the radiating fins 11, but the present invention is not limited to this. That is, as will be described later, it is sufficient that the radiating fins 11 can be cooled. Specifically, a gas having a component other than air or a liquid can be used. Moreover, the shape of the radiation fin 11 is not restricted to the shape demonstrated in the present Example, It can set suitably. That is, it is only necessary to increase the contact area with the air on the outer wall surface of the pack case 10 by forming the radiation fins 11.

  The battery module 20 has a plurality of single cells (electric storage elements) 21 arranged side by side in the X direction, and a spacer 22 is located between the two single cells 21 arranged adjacent to each other. Yes. As the cell 21, a secondary battery such as a nickel metal hydride battery or a lithium ion battery can be used. In addition, an electric double layer capacitor can be used instead of the secondary battery. The number of single cells 21 constituting the battery module 20 can be set as appropriate based on the output performance that the battery module 20 has.

  The spacer 22 is formed of an insulating material such as resin and has a plurality of protrusions 22a. Each protrusion 22a extends from one end of the spacer 22 toward the other end in the Z direction. The plurality of protrusions 22a are arranged side by side in the Y direction. The tip of each protrusion 22 a is in contact with the absorbent sheet 23, and a space extending in the Z direction is formed between the spacer 22 and the absorbent sheet 23. Moreover, the surface on the opposite side to the surface (YZ plane) in which the some protrusion part 22a was formed among the spacers 22 is comprised by the substantially flat surface, and the side surface (YZ) of the cell 21 is comprised. In contact with a flat surface.

  A positive electrode terminal 21 a and a negative electrode terminal 21 b are provided on the upper surface of the unit cell 21. The unit cell 21 includes a power generation element and a battery case that houses the power generation element. The power generation element is an element that can be charged and discharged, and specifically includes a positive electrode element, a negative electrode element, and an electrolyte positioned between the positive electrode element and the negative electrode element. The positive terminal 21a is electrically connected to the positive element of the power generation element, and the negative terminal 21b is electrically connected to the negative element of the power generation element.

  The positive terminal 21a of each unit cell 21 is electrically connected to the negative terminal 21b of another unit cell 21 arranged adjacent to the unit cell 21 via a bus bar (not shown). And the several cell 21 which comprises the battery module 20 is electrically connected in series.

  Both ends of the battery module 20 in the X direction are in contact with the inner wall surface of the pack case 10. Specifically, in the battery module 20, the unit cell 21 positioned at one end in the X direction is in contact with the pack case 10, and the spacer 22 positioned at the other end in the X direction is in contact with the pack case 10. Yes. The pack case 10 gives the battery module 20 a binding force indicated by an arrow F in FIG. Thereby, the spacer 22 and the absorption sheet 23 are brought into close contact with the two side surfaces (YZ plane) of the unit cell 21, or the spacer 22 and the absorption sheet 23 are brought into close contact with each other.

  In the present embodiment, the pack case 10 is used to apply the restraining force F to the battery module 20. However, the present invention is not limited to this, and the battery module 20 can be provided with the restraining force F. I just need it. For example, a pair of end plates can be disposed at both ends in the X direction of the battery module 20, and these end plates can be connected by rods extending in the X direction. Even with such a structure, the binding force F can be applied to the battery module 20. On the other hand, although the structure which does not give the restraining force F with respect to the battery module 20 may be sufficient, it is preferable that the absorption sheet 23 is made to contact the cell 21 using an adhesive agent etc., for example.

  A safety valve 30 is provided on the side surface of the pack case 10. The safety valve 30 is provided to discharge the gas to the outside of the pack case 10 when gas is generated from the unit cell 21. Here, if the unit cell 21 is overcharged or the like, gas may be generated from the power generation element in the unit cell 21. For this reason, the battery case of the unit cell 21 is provided with a safety valve (not shown) for discharging the gas generated from the power generation element to the outside of the battery case.

  When the internal pressure of the pack case 10 reaches the operating pressure of the safety valve 30 by discharging the gas from the unit cell 21, the safety valve 30 switches from the closed state to the open state. And the gas which passed the safety valve 30 moves along the exhaust duct 31 connected to the outer wall surface of the pack case 10, and is discharged | emitted outside the vehicle.

  As the safety valve 30 or the safety valve provided in the battery case, a destructive type valve or a return type valve can be used. A destructive valve is a valve that changes irreversibly from a closed state to an open state by plastic deformation. The return type valve is a valve that can reversibly change between a closed state and an open state in accordance with a change in the internal pressure of the pack case 10.

  The absorbent sheet 23 disposed between the unit cell 21 and the spacer 22 is formed into a sheet shape by injection molding a mixture of pulp fibers and a binder. By this injection molding, the limit surface pressure (allowable surface pressure) of the absorbent sheet 23 can be increased, and even if it receives the restraining force F from the unit cell 21 and the spacer 22, it can be made difficult to deform. Further, the absorbent sheet 23 has a size substantially equal to that of the unit cell 21 and the spacer 22 when viewed from the X direction. In addition, the magnitude | size (shape) of the absorption sheet 23 in a YZ plane and the thickness (length of a X direction) of the absorption sheet 23 can be set suitably.

  On the other hand, a liquid refrigerant 40 is accommodated in the pack case 10, and the refrigerant 40 is in contact with the lower part of the battery module 10 as shown in FIG. 1. In other words, the liquid level 40 a of the refrigerant 40 is lower than the upper surface of the battery module 10, and the refrigerant 40 is in contact with each of the unit cell 21, the spacer 22, and the absorbent sheet 23. The refrigerant 40 is an insulating liquid, and for example, perfluorocarbon or fluorine-based inert liquid can be used. Examples of the fluorinated inert liquid include Novec HFE (Hydro Fluoro Ether) manufactured by 3M and Fluorinert.

  The absorbent sheet 23 is composed of fibers and is a porous body. For this reason, the refrigerant 40 is sucked up by the absorption sheet 23 by a capillary phenomenon, and the refrigerant 40 is held in the entire interior of the absorption sheet 23. Here, the amount of the refrigerant 40 may be an amount that allows the refrigerant 40 to be absorbed by the plurality of absorption sheets 23 included in the battery module 20.

  In the battery pack 1 of the present embodiment, when the unit cell 21 generates heat due to charging / discharging or the like, this heat is transmitted to the absorption sheet 23 that is in contact with the unit cell 21 in the heat generation state. Here, as shown in FIG. 3, the refrigerant 40 absorbed by the absorbent sheet 23 evaporates by receiving heat from the unit cells 21. Thus, by evaporating the refrigerant 40, the heat generated in the unit cell 21 can be absorbed as the heat of vaporization of the refrigerant 40, and the temperature rise of the unit cell 21 can be suppressed.

  In the present embodiment, the refrigerant 40 is a liquid that easily evaporates by receiving heat from the unit cell 21, and the boiling point of the refrigerant 40 can be set to a temperature at which the refrigerant 40 is to be evaporated. Based on this set temperature, the specific material of the refrigerant 40 can be determined.

  When the refrigerant 40 in the absorption sheet 23 receives heat from the unit cells 21 and evaporates, the vapor of the refrigerant 40 moves upward along the protrusions 22 a of the spacers 22. As described above, a space S extending in the Z direction is formed between the spacer 22 and the absorbent sheet 23 by the protrusion 22a. For this reason, the vapor of the refrigerant 40 moves upward along the space S. In the lower part of the battery module 20, since the refrigerant 40 is in direct contact with the unit cell 21, the refrigerant 40 is evaporated by receiving heat from the unit cell 21.

  Here, in this embodiment, the protrusion 22a extending in the Z direction is formed on the spacer 22, but this is not restrictive. That is, a space for moving the vapor of the refrigerant 40 upward is required between the spacer 22 and the absorbent sheet 23, and the shape of the protrusion 22a can be set as appropriate. For example, the protrusions 22a can be formed in a cylindrical shape, and these protrusions 22a can be arranged in a matrix in the YZ plane.

  When the vapor of the refrigerant 40 reaches the upper surface of the pack case 10, the heat of the vapor is transmitted to the pack case 10. Thereby, the vapor | steam of the refrigerant | coolant 40 is liquefied according to the fall of temperature. The refrigerant 40 that has become liquid falls toward the bottom surface of the pack case 10 due to the action of gravity, and accumulates on the bottom surface of the pack case 10. In the present embodiment, the air from the fan 50 is supplied to the heat radiating fins 11 provided on the upper surface of the pack case 10 to actively cool the upper surface of the pack case 10. For this reason, the vapor of the refrigerant 40 can be easily liquefied by reaching the upper surface of the pack case 10.

  In the present embodiment, heat radiation from the side surface of the unit cell 21 can be efficiently performed with a simple configuration in which the absorption sheet 23 is brought into contact with the side surface (YZ plane) of the unit cell 21. That is, by using the absorbent sheet 23, the refrigerant 40 can be spread over the entire side surface of the unit cell 21, and the refrigerant 40 can be evaporated over the entire side surface of the unit cell 21. Here, if the protrusion 22a of the spacer 22 is brought into contact with the side surface of the unit cell 21 as in the configuration described in Patent Document 2, the heat dissipation efficiency of the unit cell 21 is reduced in this contact region. In the present embodiment, since the absorbing sheet 23 including the refrigerant 40 is located between the protrusion 22a and the single cell 21, the refrigerant 40 can be evaporated and the temperature increase of the single cell 21 can be suppressed. .

  In the present embodiment, since the absorbent sheet 23 can suck up the refrigerant 40 by capillary action, it is not necessary to bring the entire surface of the unit cell 21 into contact with the refrigerant 40. In other words, unlike the configuration described in Patent Document 1, the liquid level 40 a of the refrigerant 40 does not need to be positioned above the upper surface of the battery module 20. Thereby, while being able to reduce the quantity of the refrigerant | coolant 40, the refrigerant | coolant 40 can be easily filled in the pack case 10. FIG. Here, when an expensive material is used as the refrigerant 40, the cost of the battery pack 1 can be reduced by reducing the amount of the refrigerant 40.

  Furthermore, since the absorbent sheet 23 is composed of pulp fibers, an increase in cost due to the use of the absorbent sheet 23 can be suppressed. Further, by using the absorbent sheet 23 made of pulp fibers, the restraining force F can be applied to the unit cells 21 and the spacers 22 constituting the battery module 20 in a stable state.

  In addition, in the present Example, although the absorption sheet 23 formed with the pulp fiber is pinched | interposed between the cell 21 and the spacer 22, it is not restricted to this. That is, the absorbent sheet 23 only needs to be able to suck up and hold the refrigerant 40 by capillary action, and may be made of a porous body. Specifically, the absorbent sheet 23 can be configured using fibers (natural fibers or chemical fibers) other than pulp fibers.

  Further, in this embodiment, the excess refrigerant 40 that is absorbed by the absorbent sheet 23 is accommodated in the lower part of the pack case 10, but the excess refrigerant 40 may be omitted. In other words, the absorbent sheet 23 may be simply allowed to absorb the refrigerant 40. Even in this case, the refrigerant 40 in the absorption sheet 23 can be evaporated by the heat from the unit cells 21, and the temperature increase of the unit cells 21 can be suppressed. Further, in this embodiment, the absorption sheet 23 is brought into contact with all the unit cells 21 constituting the battery module 20, but it is also possible to simply bring the absorption sheet 23 into contact with at least one unit cell 21.

  Furthermore, in the present embodiment, the absorbent sheet 23 is brought into contact with only one side surface (YZ plane) of the unit cell 21, but this is not restrictive. For example, as shown in FIG. 4, the absorbent sheet 23 can be brought into contact with two side surfaces (YZ plane) of the unit cell 21. Here, FIG. 4 is a diagram showing a part of the configuration of the battery module 20 which is a modification of the present embodiment, and the same reference numerals are used for members having the same functions as the members described in the present embodiment. ing. In the configuration shown in FIG. 4, the absorption sheets 23 are positioned on both sides in the X direction with respect to the spacers 22, and thus the protrusions 22 a are formed on two surfaces (YZ planes) facing these absorption sheets 23. Is formed.

  In the present embodiment, the spacer 22 and the absorbent sheet 23 are disposed between two unit cells 21 adjacent in the X direction, but the present invention is not limited to this. Specifically, the spacer 22 may be omitted, and only the absorbent sheet 23 may be disposed between two unit cells 21 adjacent in the X direction. In this case, the absorption sheet 23 comes into contact with the side surfaces (YZ plane) of the two unit cells 21. Even with such a configuration, the refrigerant 40 absorbed in the absorbent sheet 23 receives heat from the unit cell 21 and evaporates, whereby the temperature increase of the unit cell 21 can be suppressed.

  In this embodiment, the absorbent sheet 23 is brought into contact with a specific side surface (YZ plane) of the unit cell 21. However, the present invention is not limited to this, and the absorbent sheet 23 is included in the outer surface of the unit cell 21. Any area may be touched. If the absorbent sheet 23 is in contact with the outer surface of the unit cell 21, the heat from the unit cell 21 evaporates the refrigerant 40 absorbed by the absorption sheet 23, and the temperature rise of the unit cell 21 can be suppressed. .

  Here, in this embodiment, the rectangular unit cell 21 is used, but another unit cell 21 such as a cylindrical unit can also be used. When the cylindrical unit cell 21 is used, for example, as shown in FIG. 5, the absorption sheet 23 that has absorbed the refrigerant 40 can be brought into contact with the outer peripheral surface of the unit cell 21.

  And as shown in FIG. 6, while arrange | positioning the cell 21 provided with the absorption sheet 23 along with one direction, the layer of the refrigerant | coolant 40 can be located along the bottom face of the pack case 10. FIG. Here, in FIGS. 5 and 6, the same reference numerals are used for members having the same functions as those described in the present embodiment. Further, the plurality of unit cells 21 can be supported by a support member. As this support member, for example, a pair of support plates (not shown) that support both end sides of each unit cell 21 can be used.

  In the configuration shown in FIG. 6, each absorbent sheet 23 sucks the refrigerant 40 by capillary action, so that the refrigerant 40 can be held in the absorbent sheet 23. Thereby, when the unit cell 21 generates heat, the temperature rise of the unit cell 21 can be suppressed by evaporating the refrigerant 40 in the absorption sheet 23.

DESCRIPTION OF SYMBOLS 1: Battery pack (electric storage apparatus) 10: Pack case 11: Radiation fin 20: Battery module 21: Single battery (electric storage element) 21a: Positive electrode terminal 21b: Negative electrode terminal 22: Spacer 22a: Protruding part 23: Absorbing sheet 30: Safety valve 31: Exhaust duct 40: Refrigerant (liquid) 50: Fan

Claims (8)

A plurality of power storage elements;
A case for housing the plurality of power storage elements in a sealed state;
An absorbent sheet that is in contact with the outer surface of the electricity storage element and absorbs a liquid refrigerant that can be evaporated by receiving heat from the electricity storage element;
A power storage device comprising:   The power storage device according to claim 1, wherein the absorption sheet absorbs the refrigerant filled in the case into the absorption sheet by using a capillary phenomenon.   The power storage device according to claim 2, wherein the absorbent sheet is formed of fibers. The plurality of power storage elements are arranged side by side in a predetermined direction with the absorption sheet and a spacer interposed therebetween,
The spacer is in contact with a surface opposite to the contact surface with the electricity storage element in the predetermined direction of the absorption sheet, and on the contact surface with the absorption sheet, the spacer from the absorption sheet The power storage device according to any one of claims 1 to 3, wherein a space for moving the vapor of the refrigerant toward the case side is formed.   The power storage device according to claim 4, wherein the spacer includes a plurality of protrusions that extend in a substantially vertical direction to form the space.   6. The power storage device according to claim 4, wherein the absorption sheet is formed in a shape along an outer shape of the power storage element when viewed from the predetermined direction.   7. The device according to claim 4, further comprising a constraining structure that applies a constraining force for bringing the power storage elements adjacent in the predetermined direction closer to each other to the plurality of power storage elements. Power storage device. The upper surface of the case has a heat radiating fin that protrudes from the outer wall surface of the case toward the outside of the case and contacts a cooling medium supplied from the outside of the power storage device. The power storage device according to any one of 7.

Images