JP2009211998A - Cooling device for battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling device for a battery pack for cooling the battery pack with an appropriate capacity. <P>SOLUTION: The cooling device 100 includes: a cooling fan device 4 for supplying cooling air to the battery pack 1 formed by arranging a plurality of modules 200, in which a plurality of flat batteries 204 are housed so as to oppose flat surfaces, so that the flat surfaces are opposed and a cooling air passage 200a is formed between the battery modules; and a battery controller 400 having a CPU 401 estimating the height H of the cooling air passage 200a and correcting the cooling capacity of the cooling fan device 4 based on the estimated height H. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a battery pack cooling apparatus.

  There is known an assembled battery in which a plurality of battery modules in which a plurality of flat batteries are stacked are further stacked (Patent Document 1). In this assembled battery, an interval is formed between the battery modules, and cooling air is passed through the assembled battery including the interval to remove heat generated by charging and discharging.

JP2008-10190

  However, when the thickness of the electrode varies depending on the state of charge, there is a problem that the cooling capacity varies because the distance between the battery modules through which the cooling air flows also varies.

  The problem to be solved by the present invention is to provide an assembled battery cooling device capable of cooling the assembled battery with an appropriate capacity.

  This invention solves the said subject by estimating the space | interval of the cooling air flow path between battery modules, and correct | amending cooling capacity according to this estimation result.

  According to the present invention, the assembled battery can be cooled with an appropriate capacity.

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

<< First Embodiment >>
First, an example of the assembled battery of this example will be described.

<Battery assembly>
FIG. 1 is a perspective view showing an example of an assembled battery according to the first embodiment. FIG. 2 is a side view taken along the line II-II in FIG.

  The assembled battery 1 of this example shown in FIG.1 and FIG.2 is a vehicle-mounted battery mounted in vehicles, such as a motor vehicle, For example, the battery module group 20 of 4 rows was arranged in the left-right direction (plane direction) in the lower case 10. FIG. It is placed in a state. The battery module group 20 is configured, for example, by stacking three battery modules 200 in the vertical direction (stacking direction). Note that the parallel number of the battery module group 20 and the number of stacked battery modules 200 can be appropriately changed according to the required output, the required operating time, and the like.

  A restraint plate 30 is provided on the uppermost part of the battery module group 20 of this example, and the battery module group 20 is interposed between the restraint plate 30 and the lower case 10 by fastening the restraint plate 30 to the lower case 10 with bolts 40. Can be fixed. In this example, spacers 50 are provided above and below the through-holes 206 (see FIG. 4) of the battery module 200 into which the bolts 40 are inserted to receive a load and secure a space for cooling air (for example, air) to pass through. Is arranged.

  FIG. 3 is an image view seen from the III direction of FIG.

  In the example shown in FIG. 3, three battery modules 200 are arranged to face each other with a spacer 50 interposed therebetween. That is, the battery modules 200 and 200 adjacent to each other in the stacking direction are arranged with a space corresponding to the thickness of the spacer 50 therebetween. In this example, the space corresponding to the thickness of the spacer 50 is used as a cooling air flow path 200a through which cooling air for cooling each battery module 200 flows.

  In this example, the cooling air is supplied through the cooling air flow path 200a on the first side (left side of FIG. 2) where the positive and negative output terminals 60A and 60B (see FIGS. 5, 7, and 8) of the battery module 200 are provided. For example, it flows from the front side to the second side (the right side in FIG. 2, eg, the back side) opposite to the second side. As will be described later, in this example, both the inlet and outlet of the cooling air are provided on the first side where the output terminals 60A and 60B are provided (see FIG. 10). The wind flows back to the first side. By flowing cooling air and cooling each battery module 200, it is possible to suppress the battery temperature from being lowered and the characteristics such as charging efficiency from being lowered.

  The clearance between the battery modules 200 and 200 adjacent to each other in the stacking direction, that is, the height H of the cooling air flow path 200a is defined by the thickness of the spacer 50 disposed between the battery modules 200 during stacking. The height H of the cooling air flow path 200a is determined in consideration of the layout of the battery module 200, dimensions necessary for functioning as the cooling air passage 200a, and the like.

  Next, an example of a battery module constituting the assembled battery 1 will be described.

《Battery module》
FIG. 4 is a perspective view showing the battery module 200 of the assembled battery of FIG. FIG. 5 is an exploded perspective view of the battery module 200 of FIG.

  The battery module 200 of this example shown in FIGS. 4 and 5 includes a casing 202 that covers the outside, and a plurality of flat batteries 204 that are stacked and held inside the casing 202. The housing 202 has a main body 2022 in which a recess 2022a is formed, and a lid 2024 that seals the recess 2022a of the main body 2022. A flat battery 204 is accommodated in the recess 2022 a of the main body 2022. In the edge portion of the lid body 2024 of this example, a tightening portion 2024a is formed by a tightening process. By tightening the tightening portion 2024a around the edge portion 2022b of the main body 2022 (a dashed-dotted line circle in FIG. 4). The main body 2022 is sealed with a lid 2024 while the flat battery 204 is housed inside.

  The casing 202 protects the low-strength flat battery 204 from external vibrations and shocks, and also plays a role of radiating heat transmitted from the flat battery 204 to the outside of the housing. For example, aluminum having good heat dissipation It is made of metal.

  Next, an example of a flat battery housed in the battery module 200 will be described.

《Flat battery》
6 is a cross-sectional view showing an example of a flat battery 204 housed in the battery module 200 of FIG.

  A flat battery 204 of this example shown in FIG. 6 is a lithium-based, flat plate, and laminated type chargeable / dischargeable thin secondary battery, and includes a battery element 250, an outer case 260, a positive electrode lead (positive electrode terminal) 270, and a negative electrode. A lead (negative electrode terminal) 280 is provided.

  The battery element 250 includes a positive electrode plate having a positive electrode active material layer 251 on a current collector 252 and a negative electrode plate having a negative electrode active material layer 253 on a current collector 252 that holds an electrolyte (not shown). It is formed by stacking via an electrolyte layer 254.

The positive electrode active material layer 251 includes a positive electrode active material, a conductive additive, a binder, and the like. Examples of the positive electrode active material include lithium-transition metal composite oxides such as LiMn ₂ O ₄ . Examples of the conductive assistant include acetylene black, carbon black, graphite, carbon fiber, and carbon nanotube. Examples of the binder include polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), and polyimide.

  The negative electrode active material layer 253 includes a negative electrode active material, a conductive additive, a binder, and the like. Examples of the negative electrode active material include graphite-based carbon material (graphite-based), hard carbon (non-graphitizable carbon material), lithium-transition metal composite oxide, and the like. In this example, it works effectively particularly when a graphite-based carbon material is contained in the negative electrode active material. When the negative electrode plate containing the graphite-based carbon material in the negative electrode active material is provided, the thickness of the electrode is likely to vary depending on the state of charge of the battery 204. As a result, the height H of the cooling air flow path 200a (see the dotted line in FIG. 3) ) Is likely to fluctuate.

  The current collector 252 is, for example, an aluminum foil, a copper foil, a stainless steel foil, a titanium foil, a nickel-aluminum clad material, a copper-aluminum clad material, a stainless steel-aluminum clad material, or a plating material of a combination of these metals. Etc. Among the above materials, a positive electrode current collector 252 is selected as a positive electrode potential, and a negative electrode current collector 252 is selected from a material that is stable at a negative electrode potential. Generally, the positive electrode current collector 252 is made of aluminum. A copper foil is used for the negative electrode current collector 252.

  The separator 254 is made of, for example, polyolefin such as polyethylene or polypropylene, polyamide, polyimide, or the like. The electrolyte held by the separator 254 is a liquid system or a fluid gel polymer system.

The electrolyte (electrolytic solution) contains an organic solvent, a supporting salt, a small amount of a surfactant, and the like. Examples of the organic solvent include cyclic carbonates such as propylene carbonate (PC) and ethylene carbonate (EC), chain carbonates such as dimethyl carbonate, and ethers such as tetrahydrofuran. Examples of the supporting salt include inorganic acid anion salts such as lithium salt (LiPF ₆ ) and organic acid anion salts such as LiCF ₃ SO ₃ . The gel polymer electrolyte includes an electrolytic solution, a host polymer, and the like. As the host polymer, a polymer having no lithium ion conductivity, such as a copolymer of polyvinylidene fluoride and hexafluoropropylene (PVDF-HFP), PAN (polyacrylonitrile (PAN), PMMA (polymethyl methacrylate (PMMA)), Examples thereof include polymers (solid polymer electrolytes) having ion conductivity such as PEO (polyethylene oxide) and PPO (polypropylene oxide).

  The exterior case 260 is formed in a bag shape by joining the peripheral edges of the sheet-shaped exterior material 262 by heat welding, and is used to accommodate the battery element 250. The exterior material 262 is a polymer-metal composite laminate film having a three-layer structure, and includes a metal layer 264 and a polymer resin layer 266 disposed on both surfaces of the metal layer 264. Examples of the metal layer 264 include metal foils such as aluminum, stainless steel, nickel, and copper. Examples of the polymer resin layer 266 include heat-welding resin films such as polyethylene, polypropylene, modified polyethylene, modified polypropylene, ionomer, and ethylene vinyl acetate. Note that the bonding of the exterior material 262 is not limited to applying heat welding.

  The positive electrode lead 270 and the negative electrode lead 280 are connected to the current collector 252 of the battery element 250 and extend from the inside of the outer case 260 to the outside in order to draw current from the battery element 250.

  Returning to FIG. 4 and FIG. 5, the plurality of flat batteries 204 are electrically connected in series or in parallel with each other's electrode terminals (the positive electrode lead 270 and the negative electrode lead 280 in FIG. 6). (When flat batteries 204 are connected in series, the positive electrode with the highest potential and the negative electrode of the battery with the lowest potential, and when connected in parallel, the positive electrode and the negative electrode of each battery) 202 are connected to positive and negative output terminals 60A and 60B. The positive and negative output terminals 60 </ b> A and 60 </ b> B are led out from the casing 202 in a direction orthogonal to the stacking direction of the battery modules 200 (in the horizontal direction when the stacking direction of the battery modules 200 is up and down).

  FIG. 7 is a front view taken along line VII-VII in FIG. FIG. 8 is a front view of another embodiment corresponding to FIG.

  The stacking direction of each battery module 200 is not particularly limited. For example, as shown in FIG. 7, the lid 2024 of each battery module 200 is the same direction as the stacking direction of each battery module 200 (upper side in FIG. 7). You may arrange so that it may face. Further, for example, as shown in FIG. 8, the lids 2024 of the battery modules 200 may be arranged so as to alternately face the stacking direction of the battery modules 200.

  When the battery modules 200 are stacked in the manner shown in FIG. 7, a plurality of two types of battery modules 200 in which the positive electrode output terminal 60A and the negative electrode output terminal 60B are arranged in reverse are prepared. Then, the output terminals 60A and 60B of the battery modules 200 stacked and adjacent to each other are arranged so as to be reversely arranged, and the conductive bus bar 70 is connected in the arrangement shown in the drawing. As a result, the output terminals 60A and 60B can be connected in series.

  When the battery modules 200 are stacked in the manner shown in FIG. 8, only one type of battery module 200 needs to be prepared. Then, the conductive bus bar 70 is connected in the illustrated arrangement. Thereby, each output terminal 60A and 60B can be connected in series.

  The bus bar 70 is fixed to the output terminals 60A and 60B and used to electrically connect the battery modules 200 to each other.

  Next, an example of the cooling device for the assembled battery 1 will be described.

<Battery cooling device>
FIG. 9 is a block diagram illustrating an example of a cooling device for the assembled battery 1 according to the first embodiment.

  The cooling device 100 for the assembled battery 1 of this example shown in FIG. 9 is mounted and used in a vehicle such as an automobile or a train. In FIG. 9, the number of flat batteries 204 (see FIGS. 5 and 6) collected for each battery module 200 is four, but the number corresponds to the number of stacked battery 204 shown in FIG. This will be explained below. In this example, only three battery modules 200 (see FIGS. 1 and 2) are shown, and cell controllers CC1, CC2, and CC3 (hereinafter also referred to as CCt) are provided for each battery module 200. The case is illustrated.

  Each cell controller CCt receives the output from the battery controller 400 and controls charging / discharging of each flat battery 204 constituting each battery module 200 for each corresponding battery module 200.

  The voltage sensor 500 detects the total voltage Vt of the assembled battery 1 and outputs it to the battery controller 400. The temperature sensor 600 detects the temperature T of the assembled battery 1 and outputs it to the battery controller 400.

  The cooling fan device 4 (cooling means) receives a drive signal from the battery controller 400 and supplies cooling air to the assembled battery 1 including the cooling air flow path 200a. The cooling fan device 4 of this example includes a cooling fan 41, a fan motor 42 that drives the cooling fan 41, and a fan drive control unit 43 that controls driving of the fan motor 42.

  In this example, the fan drive control unit 43 includes a PWM conversion circuit, and can adjust the amount of cooling air supplied from the cooling fan 41 to the assembled battery 1 including the cooling air flow path 200a. Note that the target duty ratio to the fan drive control unit 43 is output from the battery controller 400. In this example, the DC voltage of the power supply 44 is converted by PWM (pulse width modulation) control to generate a pulse voltage corresponding to the target duty ratio and apply it to the fan motor 42.

  The battery controller 400 communicates with each cell controller CCt by serial communication via the transmission terminal SD and the reception terminal RD, and controls each cell controller CCt to manage the assembled battery 1. In addition to this, the battery controller 400 also performs a process of correcting the cooling state of the assembled battery 1.

  The battery controller 400 includes a CPU 401 (interval estimation means, correction means) and a memory (RAM) 402. The CPU 401 in this example executes a predetermined process (correction process) based on the charge capacity (SOC: State Of Charge) of the assembled battery 1 calculated based on the total voltage Vt of the assembled battery 1 detected by the voltage sensor 500. To do. Details thereof will be described later.

  Next, an example of mounting the cooling device 100 for the assembled battery 1 will be described.

<Example of mounting an assembled battery cooling device>
FIG. 10 is a diagram showing an example of mounting the assembled battery cooling device according to the first embodiment.

  FIG. 10 shows a case 11 in which the above-described cooling fan device 4 and the assembled battery 1 are accommodated, and this case 11 is mounted behind the rear seat of the vehicle 3. Cooling air can be introduced into the case 11 from the vehicle interior by the cooling fan device 4 and discharged from the case 11 to the outside of the vehicle interior.

  An inlet duct 6 and an outlet duct 7 are connected to the case 11. The inlet duct 6 is a duct that introduces air introduced from the intake opening 8 through the chamber case 5 and the cooling fan device 4 into the case 11. The outlet duct 7 is a duct that guides air introduced into the case 11.

  In the cooling device 100 of this example, when the cooling fan device 4 is operated, the air in the vehicle interior is introduced into the intake opening 8 that opens to the vehicle interior side. The air introduced from the intake opening 8 is introduced into the case 11 via the chamber case 5, the cooling fan 41, and the inlet duct 6. The air introduced into the case 11 cools the assembled battery 1 in the case 11, and is then discharged from the case 11 through the outlet duct 7 through the discharge port 9 that opens to the outside of the passenger compartment.

  Next, the correction process according to this example will be described.

《Correction processing》
FIG. 11 is a flowchart showing the correction process according to the first embodiment.

  In the example shown in FIGS. 9 and 11, first, in step S <b> 1, the temperature sensor 600 detects the assembled battery temperature T of the assembled battery 1 and outputs it to the CPU 401.

  Next, in step S <b> 2, the CPU 401 acquires a predetermined set temperature T <b> 0 of the assembled battery 1 stored in advance in the memory (RAM) 402, and the assembled battery detected by the set temperature T <b> 0 and the temperature sensor 600. The temperature T is compared, and it is determined whether or not the assembled battery temperature T is higher than the set temperature T0.

  If T> T0 in step S2 (Yes in S2), the process proceeds to step S3, and the CPU 401 sends a control signal to start cooling the assembled battery 1 to the cooling fan device 4. The cooling fan device 4 receives the output from the CPU 401 and starts cooling the assembled battery 1.

  The cooling condition at the start of cooling is not particularly limited, but it is desirable to consider the future temperature rise factor of the assembled battery 1. The future temperature rise factor of the assembled battery 1 is, for example, estimating the future charge / discharge amount of the assembled battery 1 according to the current assembled battery temperature T, engine speed, accelerator opening, engine motor torque, etc. Alternatively, it can be estimated by estimating the cooling capacity of the assembled battery 1 according to, for example, the temperature inside the vehicle, the air volume of the air conditioner, and the like. An appropriate fan rotation speed can be set based on the future temperature rise factor of the assembled battery 1 estimated in this way. For example, the fan air volume is estimated such that “assembled battery temperature T−target battery temperature + temperature increase factor− (cooling capacity × fan air volume)” is zero, and the fan speed is set so that the fan air volume becomes the air volume. Set.

  The charging efficiency of the assembled battery 1 generally tends to decrease as the assembled battery temperature T increases. When the assembled battery temperature T is equal to or lower than a predetermined set temperature T0 (for example, 35 ° C.) (No in S2), the charging efficiency of the assembled battery 1 follows a gentle change linearly from 100%. In this example, in this case, the process returns to step S1. In contrast, when assembled battery temperature T exceeds set temperature T0 (Yes in S2), the charging efficiency of assembled battery 1 rapidly decreases. Therefore, in this example, the set temperature T0 is set in step S2, and when the assembled battery temperature T exceeds the set temperature T0 (T> T0), the process proceeds to step S3 and cooling of the assembled battery 1 is started. is there.

  After starting the cooling of the assembled battery 1 in step S3, the voltage sensor 500 detects the total voltage Vt of the assembled battery 1 and outputs it to the CPU 401 in step S4.

  Next, in step S <b> 5, the CPU 401 calculates the SOC of the assembled battery 1 based on the total voltage Vt of the assembled battery 1 detected by the voltage sensor 500. It is preferable to calculate the SOC of the assembled battery 1 in consideration of deterioration of the assembled battery 1. For example, a possible output-SOC correlation diagram (not shown) of the assembled battery 1 is stored in the memory (RAM) 402 in advance, and the SOC of the assembled battery 1 considering deterioration of the assembled battery 1 is calculated based on this correlation diagram. Can be calculated.

  Next, in step S6, the CPU 401 estimates the height H (see FIG. 3) of the cooling air flow path 200a based on the SOC of the assembled battery 1 calculated in step S5.

  As described above, in the flat battery 204 (FIGS. 5 and 6), when a graphite-based carbon material is contained in the negative electrode active material of the negative electrode active material layer 253 (see FIG. 6) constituting the negative electrode plate, the flat battery The thickness of the electrode is likely to vary depending on the state of charge of the battery 204. When the electrode thickness varies, the height H of the cooling air flow path 200a varies (see the dotted line in FIG. 3), which causes the cooling state to vary. Therefore, in this example, in step S6, the fluctuation state of the height H of the cooling air flow path 200a generated when the flat battery 204 having the negative electrode plate containing the graphite-based carbon material is used is estimated.

  FIG. 12 is a correlation diagram showing the relationship between the SOC (unit: “%”) of the battery pack 1 and the height H (unit: “mm”) of the cooling air flow path 200a.

  When the assembled battery 1 is completely discharged, the height H of the cooling air flow path 200a indicates the maximum height (point P1). As the assembled battery 1 is fully discharged and the SOC of the assembled battery 1 increases, the height H of the cooling air flow path 200a decreases (point P2). When the height H decreases, the cooling efficiency of each battery module 200 decreases accordingly.

  Note that the SOC of the assembled battery 1 (0% when the discharge is completed) is inversely proportional to the depth of discharge (DOD: Depth of Discharge. 100% when the discharge is completed). Therefore, the horizontal axis of FIG. 12 may be the discharge depth DOD of the assembled battery 1. In this case, in step S5, the discharge depth DOD of the assembled battery 1 is calculated, and in step S6, the height H can be estimated based on the DOD of the assembled battery 1 calculated in step S5.

  Returning to FIG. 11, in step S7, the CPU 401 corrects the fan air volume of the cooling fan device 4 based on the height H of the cooling air flow path 200a estimated in step S6.

  Here, as the height H of the cooling air passage 200a decreases, the cross-sectional area of the cooling air passage 200a decreases. For this reason, even if the cooling air is introduced at a predetermined air volume or air speed, a pressure loss (pressure resistance) ΔP occurs, and the cooling performance cannot be improved.

In general, the pressure loss ΔP is expressed by the following equation, where A is the proportionality constant, and x is the fan air volume (unit: “m ³ / min”) or the wind speed (unit: “m / min”).

[Formula 1] ΔP = Ax ² (1)
A (proportional constant) in Equation 1 varies depending on the state of the assembled battery 1. Specifically, when the electrode (negative electrode plate) of the flat battery 204 (FIGS. 5 and 6) expands and its thickness increases (see the dotted line in FIG. 3), the height of the cooling air flow path 200a is accordingly increased. H decreases, and as a result, ΔP increases. On the other hand, when the negative electrode plate of the flat battery 204 is not expanded, the thickness of the negative electrode plate does not increase, and accordingly the height H of the cooling air flow path 200a does not decrease, and as a result ΔP does not increase. . In this example, Equation 1 is stored in the memory (RAM) 402 in advance. In addition, a function expressed by the following equation when the height H of the cooling air flow path 200a is y is calculated and stored in the memory (RAM) 402 in advance.

[Expression 2] A = F (y) (2)
That is, in step S7 of this example, first, the height H of the cooling air flow path 200a estimated in step S6 is applied to the function of Equation 2 stored in advance in the memory 402, so that the proportionality constant A (that is, the battery pack 1). State). Next, the pressure loss ΔP is calculated by applying Equation 1 stored in the memory 402 in advance to the calculated proportionality constant A. Next, the fan air volume of the cooling fan device 4 is corrected based on the calculated pressure loss ΔP.

  FIG. 13 is a correlation diagram between the pressure loss ΔP and the fan wind speed x.

  In this example, when the fan wind speed x is necessary when the assembled battery 1 is in a certain charged state, the estimated fan air flow rate of the cooling fan device 4 is 40% when the estimated value of the height H of the cooling air flow path 200a is 2 mm, for example. Thus, when the estimated value of the height H of the cooling air flow path 200a is, for example, 1 mm, the fan air volume of the cooling fan device 4 is corrected so as to be 50%.

  Returning to FIG. 11, next, in step S <b> 8, the CPU 401 sends a signal related to the target duty ratio corresponding to the fan air volume corrected in step S <b> 7 to the fan drive control unit 43 (see FIG. 9) of the cooling fan device 4. Send it out. Upon receiving the output, the fan drive control unit 43 acquires a pulse voltage corresponding to the target duty ratio, applies this to the fan motor 42, and rotates the cooling fan 41 so as to obtain a predetermined air volume.

  In this example, when the fan air volume of the cooling fan device 4 is corrected to 100%, for example, the fan drive control unit 43 may turn on the switching element and apply all of the power supply voltage. When correcting to 50%, the fan drive control unit 43 may halve the ON / OFF time of the switching element and apply half of the power supply voltage. In the case of correcting to 0%, the fan drive control unit 43 may turn off the switching element and stop the application of the power supply voltage.

  If the fan air volume of the cooling fan device 4 is determined based on the temperature T of the assembled battery 1 and the assembled battery 1 is cooled based on the determined fan air volume, the SOC of the assembled battery 1 is high, and the cooling air flow path 200a. When the height H is small, the cooling effect is smaller than the assumed cooling performance. For this reason, the temperature rise of the assembled battery 1 cannot be suppressed. As a result, it cannot be cooled with an appropriate capacity. Moreover, when the SOC of the assembled battery 1 is low and the height H of the cooling air flow path 200a is large, the cooling effect is larger than the assumed cooling performance (the fan air volume is larger than necessary). For this reason, in order not to consume useless power, the rotation and stop of the fan must be repeated, and the rotation of the fan is not stable.

  On the other hand, according to the cooling device 100 of the assembled battery 1 of this example, the fan air volume of the cooling fan device 4 is corrected based on the height H of the cooling air flow path 200a estimated based on the SOC of the assembled battery 1. Then, a signal related to the target duty ratio corresponding to the corrected fan air volume is sent to the fan drive control unit 43 of the cooling fan device 4 to apply an appropriate voltage to the fan motor 42, and thereby an appropriate air volume to the cooling fan 41. Generate cooling air.

  In this example, when the SOC of the assembled battery 1 is high and the height H of the cooling air flow path 200a is small, the assumed cooling performance and the cooling effect coincide. For this reason, the temperature rise of the assembled battery 1 can be suppressed effectively. As a result, it is possible to cool with an appropriate capacity. Further, when the SOC of the assembled battery 1 is low and the height H of the cooling air flow path 200a is large, the assumed cooling performance and the cooling effect are the same as in the case where the height H is small. For this reason, it is not necessary to repeat the rotation and stop of the fan so as not to consume unnecessary power, and the rotation of the fan is stabilized. As a result, the assembled battery 1 can be cooled with an appropriate capacity.

<< Second Embodiment >>
FIG. 14 is a block diagram illustrating an example of a cooling device for the assembled battery 1 according to the second embodiment. FIG. 15 is a perspective view showing a configuration example of one battery module group 20 according to the second embodiment.

  In the cooling device 100a for the assembled battery 1 of this example shown in FIGS. 14 and 15, a strain gauge 800 for detecting the strain (elongation rate or shrinkage rate) of each battery module 200 is arranged for each battery module 200. This point is different from the first embodiment, and other parts are the same as those of the first embodiment.

  The strain gauge 800 of this example detects the strain in the vertical direction (stacking direction) of each battery module 200 and outputs it to the battery controller 400a. Note that the strain gauge 800 may detect strain in the thickness direction of the plurality of flat batteries 204 (see FIGS. 5 and 6) constituting each battery module 20.

  The battery controller 400a of this example includes a CPU 401a (interval estimation means, correction means) and a memory 402a. The CPU 401a of this example executes a predetermined process (correction process) based on the amount of strain in the stacking direction of each battery module 20 detected by the strain gauge 800.

  Next, the correction process according to this example will be described.

《Correction processing》
FIG. 16 is a flowchart showing the correction process of the second embodiment.

  In the example shown in FIG. 16, first, in step S10, the CPU 401a executes steps S1 to S3 in FIG. After starting cooling of the assembled battery 1 in step S10, the strain gauge 800 detects the strain amount of each battery module 200 and outputs it to the CPU 401a in step S20.

  Next, in step S30, the CPU 401a estimates the height H (see FIG. 3) of the cooling air flow path 200a based on the strain amount of each battery module 200 detected by the strain gauge 800.

  As described in the first embodiment, in the flat battery 204 (FIGS. 5 and 6), the negative electrode active material of the negative electrode active material layer 253 (see FIG. 6) constituting the negative electrode plate contains a graphite-based carbon material. In this case, the thickness of the electrode is likely to vary depending on the state of charge of the flat battery 204 (see the dotted line in FIG. 3).

  FIG. 17 is a correlation diagram showing the relationship between the amount of strain (unit: “micro strain”) on the surface of the battery module 200 and the height H (unit: “mm”) of the cooling air flow path 200a.

  When the assembled battery 1 completes discharging, that is, when each flat battery 204 (see FIGS. 4 and 5) constituting each battery module 200 is discharged to a predetermined voltage (for example, discharge end voltage), the surface of the battery module 200 is Distortion is lost (zero distortion). At this time, the height H of the cooling air flow path 200a indicates the maximum height (point P3). As this assembled battery 1 is charged and the SOC of the assembled battery 1 increases, the amount of distortion on the surface of each battery module 200 increases, and the height H of the cooling air flow path 200a decreases accordingly. (P4 point). When the height H decreases, the cooling efficiency of each battery module 200 decreases accordingly.

  Returning to FIG. 16, next, in step S40, the CPU 401a executes steps S7 and S8 of FIG.

  As described above, according to the cooling device 100a of the assembled battery 1 of this example, the fan air volume of the cooling fan device 4 is set based on the height H of the cooling air flow path 200a estimated based on the distortion amount of each battery module 200. A signal relating to the target duty ratio corresponding to the corrected fan air volume is sent to the fan drive control unit 43 of the cooling fan device 4 to apply an appropriate voltage to the fan motor 42, and thus an appropriate voltage is applied to the cooling fan 41. Generates cooling air of the air volume. As a result, as in the case of the first embodiment, the assembled battery 1 can be cooled with an appropriate cooling capacity.

<< Third Embodiment >>
In short, in both the first embodiment and the second embodiment described above, the assembled battery 1 is cooled with an appropriate cooling capacity by correcting the fan air volume (or wind speed) of the cooling fan device 4.

  However, the above-described correction target is the temperature of the cooling air taken in by the cooling fan device 4 or the cooling air supplied from the cooling fan device 4 instead of or together with the fan air volume (or the wind speed) of the cooling fan device 4. It may be temperature.

  For example, when considering the case where two types of cooling air having different temperatures are supplied to the assembled battery 1 with the same air volume (or wind speed), it is compared with a cooling air having a high temperature (hereinafter referred to as “hot air”). Cooling air with lower temperature (hereinafter referred to as “cold air”) has better cooling capacity. Therefore, when a certain cooling capacity is required, the air volume can be reduced with the low temperature wind. That is, in the present invention, the cooling fan device is based on the height H of the cooling air flow path 200a estimated based on the SOC of the assembled battery 1 (first embodiment) or the distortion amount of each battery module 200 (second embodiment). The aspect which correct | amends the temperature of the cooling wind which 4 takes in is also included.

  In order to realize such a mode, for example, on the downstream side of the cooling fan 41 (left side in FIG. 9), a cooler (not shown) such as an evaporator (evaporator) and the temperature of the cooling air taken in by the cooling fan 41 are detected. And a temperature sensor (not shown) that controls the cooling performance of the cooler based on outputs from the battery controllers 400 and 400a.

  Also according to this embodiment, the same effects as those of the first embodiment and the second embodiment described above can be achieved.

FIG. 1 is a perspective view showing an example of an assembled battery according to the first embodiment. FIG. 2 is a side view taken along the line II-II in FIG. FIG. 3 is an image view seen from the III direction of FIG. FIG. 4 is a perspective view showing a battery module of the assembled battery of FIG. FIG. 5 is an exploded perspective view of the battery module of FIG. 6 is a cross-sectional view showing an example of a flat battery housed in the battery module of FIG. FIG. 7 is a front view taken along line VII-VII in FIG. FIG. 8 is a front view of another embodiment corresponding to FIG. FIG. 9 is a block diagram illustrating an example of a battery pack cooling device according to the first embodiment. FIG. 10 is a diagram showing an example of mounting the assembled battery cooling device according to the first embodiment. FIG. 11 is a flowchart showing the correction process according to the first embodiment. FIG. 12 is a correlation diagram showing the relationship between the SOC of the battery pack and the height of the cooling air flow path. FIG. 13 is a correlation diagram between the pressure loss ΔP and the fan wind speed x. FIG. 14 is a block diagram illustrating an example of a battery pack cooling apparatus according to the second embodiment. FIG. 15 is a perspective view showing a configuration example of one battery module group according to the second embodiment. FIG. 16 is a flowchart showing the correction process of the second embodiment. FIG. 17 is a correlation diagram showing the relationship between the amount of strain on the battery module surface and the height of the cooling air flow path.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Battery pack 20 ... Battery module group 200 ... Battery module 200a ... Cooling air flow path 204 ... Flat battery 250 ... Battery element 252 ... Current collector 253 ... Negative electrode active material layer (negative electrode plate)
50 ... Spacers 100, 100a ... Cooling device (battery battery cooling device)
4. Cooling fan device (cooling means)
DESCRIPTION OF SYMBOLS 41 ... Cooling fan 42 ... Fan motor 43 ... Fan drive control part 44 ... Power supply 400, 400a ... Battery controller 401, 401a ... CPU (space | interval estimation means, correction | amendment means)
402, 402a ... Memory 500 ... Voltage sensor 600 ... Temperature sensor 800 ... Strain gauge

Claims (3)

An apparatus for cooling an assembled battery in which a plurality of flat batteries are accommodated so that the flat surfaces are opposed to each other so that a cooling air flow path is formed between the battery modules while the flat surfaces are opposed to each other. There,
Cooling means for supplying cooling air to the assembled battery;
An interval estimating means for estimating an interval of the cooling air flow path;
A battery pack cooling apparatus comprising: a correction unit that corrects a cooling capacity of the cooling unit based on the interval estimated by the interval estimation unit. The battery pack cooling device according to claim 1,
The interval estimating means estimates the interval based on a charge capacity of the assembled battery, and the assembled battery cooling device. The battery pack cooling device according to claim 1,
The said space | interval estimation means estimates the said space | interval based on at least any one of the deformation amount of the lamination direction of the said battery module, and the deformation amount of the thickness direction of the said flat battery, The cooling device of the assembled battery characterized by the above-mentioned.

Images