JP6976762B2 - Battery pack - Google Patents

Description

The present invention relates to a battery pack.

Vehicles such as electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid vehicles (PHEVs) are equipped with, for example, a battery pack as a power source for supplying power necessary for driving a motor as a drive source. The battery pack contains, for example, a plurality of batteries (secondary batteries), and each battery is connected in series and / or in parallel. As the battery housed in the battery pack, for example, a lithium ion battery is used. Lithium-ion batteries have reduced input / output characteristics at low temperatures. Therefore, by installing a large-capacity lithium-ion battery so as not to interfere with the start of the vehicle at low temperatures, the input / output load per capacity is reduced. For example, in Patent Document 1, it is possible to prevent the temperature of the battery from rising, but it has not yet ensured the input / output characteristics of the battery at low temperatures.

Japanese Patent Application No. 2016-163572

As a method of ensuring the input / output characteristics of the battery at low temperature, for example, there is a method of heating the battery itself with a heater. If the heater is arranged so as to be in contact with all the batteries, it is necessary to provide a gap between the batteries, and the energy density with respect to the volume of the battery pack decreases, so there is room for improvement.

An object of the present invention is to provide a battery pack capable of suppressing a decrease in battery output at low temperatures.

In order to achieve the above object, the battery pack according to the present invention includes a housing having thermal conductivity, a plurality of batteries arranged in the internal space of the housing and held in the housing, and the housing. A latent heat storage member that is housed in the body and that directly contacts at least a part of each of the batteries and shifts to a supercooled state below the freezing point, and a supercooling releasing means for releasing the supercooled state of the latent heat storage member. The latent heat storage member has a melting point that changes from a solid phase to a liquid phase at a temperature lower than the temperature corresponding to the upper limit temperature of the operating temperature range of the battery, and is in the supercooled state below the freezing point. And the supercooled state is maintained until the temperature at which the supercooled state is naturally released, and the latent heat storage member is stored in the inner bottom surface of the housing vertically facing the plurality of batteries. However, the latent heat storage member is housed in the liquid phase, leaving the internal space of the housing, and is stored so as to cover at least a part of each of the batteries, and the supercooling releasing means is the battery pack. A start detecting means for detecting the start of the vehicle driven by the above means is provided, and when the start of the vehicle is detected by the start detection means, arbitrary energy is applied to the latent heat storage member to release the supercooled state. When the temperature of the battery is equal to or lower than the temperature corresponding to the freezing point of the latent heat storage member and the outside temperature is equal to or lower than the first threshold temperature at which the battery needs to be heated at the time of starting after the vehicle has stopped. , The supercooled state is released .

Further, in the battery pack, in the overcooling release means, after the vehicle is stopped, the temperature of the battery is equal to or lower than the battery temperature corresponding to the freezing point of the latent heat storage member, and the outside air temperature is the first threshold value. It is preferable to release the overcooling state when the temperature exceeds the temperature and the temperature of the battery is equal to or lower than the temperature obtained by adding the second threshold temperature to the outside air temperature.

According to the battery pack according to the present invention, there is an effect that a decrease in battery output at low temperature can be suppressed.

FIG. 1 is a partial plan view showing a schematic configuration of a battery pack according to an embodiment. FIG. 2 is a cross-sectional view taken along the line AA in FIG. FIG. 3 is a diagram showing an example of the DSC curve of the latent heat storage member according to the embodiment. FIG. 4 is a flowchart showing the operation of releasing the supercooled state of the BMU according to the embodiment. FIG. 5 is a graph showing the temperature drop time of the battery and the ratio of the temperature difference between the battery temperature and the outside air temperature according to the embodiment. FIG. 6 is a partial plan view showing a schematic configuration of a battery pack according to a modified example of the embodiment. FIG. 7 is a cross-sectional view taken along the line BB in FIG.

Hereinafter, the battery pack according to the embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiments shown below. In addition, the components in the embodiments shown below include those that can be easily replaced by those skilled in the art, or those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate.

[Embodiment]
The battery pack according to this embodiment will be described. FIG. 1 is a partial plan view showing a schematic configuration of a battery pack according to an embodiment. FIG. 2 is a cross-sectional view taken along the line AA in FIG. FIG. 3 is a diagram showing an example of the DSC curve of the latent heat storage member according to the embodiment. FIG. 4 is a flowchart showing the operation of releasing the supercooled state of the BMU according to the embodiment. FIG. 5 is a graph showing the temperature drop time of the battery and the ratio of the temperature difference between the battery temperature and the outside air temperature according to the embodiment. Note that FIG. 1 (also in FIG. 6) is a diagram showing a state in which the lid (not shown) of the housing is removed to expose the internal space to the outside. Here, the X direction of FIG. 1 (the same applies to FIGS. 2, 6, and 7) is the width direction of the battery pack in the embodiment shown below. The Y direction is the depth direction of the battery pack in the embodiment shown below, and is a direction orthogonal to the width direction. The Z direction is the vertical direction of the battery pack in the embodiment shown below, and is a direction orthogonal to the width direction and the depth direction.

The battery pack 1A according to the present embodiment is mounted on a vehicle that uses a motor as a drive source, for example, an electric vehicle (EV), a hybrid vehicle (HEV), a plug-in hybrid vehicle (PHEV), or the like, and supplies power to the motor. It is a voltage power supply. As shown in FIGS. 1 and 2, the battery pack 1A includes a housing 2, a plurality of batteries 3, a latent heat storage member 4, and a supercooling release unit 6.

The housing 2 accommodates a plurality of batteries 3, a latent heat storage member 4, and a holding member (not shown). The housing 2 is provided, for example, in a place where the outer surface can come into contact with the outside air taken in from the outside of the vehicle. The housing 2 in the present embodiment is formed in a box shape having an internal space 2a. The housing 2 has thermal conductivity, and is made of, for example, iron (Fe), copper (Cu), aluminum (Al), or the like. The housing 2 closes the internal space 2a with a lid. When the battery pack 1A is required to be waterproof, a waterproof structure is formed between the housing 2 and the lid to seal the internal space 2a.

Each of the plurality of batteries 3 is a secondary battery that can be charged and discharged. The battery 3 of the present embodiment is composed of, for example, a cylindrical lithium ion battery extending in the vertical direction. The plurality of batteries 3 are arranged in the internal space 2a of the housing 2 and are held in the housing 2 by a holding member. The plurality of batteries 3 in the present embodiment are arranged in a staggered or square grid pattern in the internal space 2a of the housing 2 at intervals in the direction orthogonal to the vertical direction (width direction or depth direction). .. The holding member for holding the plurality of batteries 3 in the housing 2 may have any structure and configuration.

The latent heat storage member 4 has heat conductivity and heat storage property, has a larger heat storage amount than the housing 2, and is composed of a latent heat storage material having both sensible heat and latent heat characteristics. The latent heat storage material typically stores heat when the phase changes (melts) from the solid phase to the liquid phase at the melting point (heat storage), and heat when the phase changes (solidifies) from the liquid phase to the solid phase at the freezing point. Has the property of releasing (dissipating heat). The latent heat storage material in the present embodiment shifts to a supercooled state below the freezing point. The supercooled state is a state in which the latent heat storage material maintains the liquid phase without changing from the liquid phase to the solid phase even if it is cooled past the freezing point. The latent heat storage material having such characteristics is also called a so-called supercooled latent heat storage material. The supercooled latent heat storage material is, for example, sodium acetate trihydrate (CH3COONa / 3H2O), nickel nitrate (II) hexahydrate. Japanese products (Ni (NO3) 2.6H2O), sodium thiosulfate pentahydrate (Na2S2O3.5H2O), calcium bromide / supercooled salt (CaBr2.6H2O) and the like can be mentioned, but any of them have the above-mentioned characteristics. However, it is not limited to these.

The latent heat storage member 4 is housed in the housing 2 and is directly thermally connected to at least each battery 3 and the housing 2. Here, the fact that the latent heat storage member 4 is directly thermally connected to each battery 3 and the housing 2 means that the latent heat storage member 4 and each battery 3 and the housing 2 come into contact with each battery 3 and the housing 2. It refers to the case where heat can be directly exchanged with the body 2. The latent heat storage member 4 in the present embodiment has fluidity during the liquid phase and is stored in the inner bottom surface 2b of the housing 2 which faces the plurality of batteries 3 in the vertical direction. The latent heat storage member 4 is housed in the liquid phase, leaving the internal space 2a of the housing 2, and is stored so as to cover at least a part of each battery 3. The latent heat storage member 4 may be filled in the housing 2 so as to completely cover all of the plurality of batteries 3 in a state where the vehicle is not tilted during the liquid phase, or the vehicle may be tilted to the maximum stability. Even if it is tilted to a corner, it may be stored so as to cover all of the plurality of batteries 3 at least partially.

The supercooling release unit 6 is a supercooling release means, and releases the supercooled state of the latent heat storage member 4. The supercooling release unit 6 includes a driver 11, a BMU 12, and an electromagnetic relay (electromagnetic relay) 13.

The driver 11 drives the electromagnetic relay 13 by applying a voltage 15 to the electromagnetic relay 13 based on the control signal 16 from the BMU 12. The driver 11 receives power from the power source 7 and drives the driver 11. The power source 7 is, for example, an auxiliary battery mounted on a vehicle and having a voltage different from that of the battery pack 1A. Auxiliary batteries are typically 12V secondary batteries for supplying power to various accessories in the vehicle. The power supply 7 is connected to the battery pack 1A via, for example, a DC / DC converter (not shown), and the output voltage of the battery pack 1A is stepped down and supplied by the DC / DC converter to be appropriately charged.

The BMU (Battery Management Unit) 12 typically detects the temperature, charging voltage, charging current, etc. of the battery 3 by a temperature sensor, a voltage sensor, a current sensor, etc., and the battery 3 does not become overcharged or overdischarged. As described above, the state of the battery 3 is monitored. The BMU 12 is, for example, a microcomputer, which is driven by receiving power supplied from the power source 7. The BMU 12 in the present embodiment has a function as a battery management means and a function as a vehicle start detection means.

As a battery management means, the BMU 12 detects the temperature of the battery 3 (hereinafter, also referred to as “battery temperature”) based on the temperature sensor signal 14 input from the temperature sensor (not shown), and also has an outside air temperature sensor (not shown). ), The outside air temperature is detected based on the external signal 17. The temperature sensor and the outside air temperature sensor are composed of, for example, a thermistor or the like. The temperature sensor is installed inside or near the battery 3. The outside air temperature sensor is installed in a place where it can come into contact with the outside air taken in from outside the vehicle.

The BMU 12 determines the start and stop of the vehicle based on an external signal 17 input from an MPU (Micro Processing Unit) (not shown) as a start detection means. The MPU controls each part in the vehicle. The external signal 17 is a general term for an outside air temperature sensor signal output from the outside air temperature sensor, a vehicle stop signal, a vehicle start signal, and the like output from the MPU. To start the vehicle, for example, the SMR (System Main Relay) (not shown) mounted on the vehicle is turned on, power can be supplied from the battery pack 1A to the motor, and the vehicle can run according to the operation of the accelerator pedal. Refers to the state. Stopping the vehicle means, for example, a state in which the SMR is turned off, power cannot be supplied from the battery pack 1A to the motor, and the vehicle cannot run immediately. After the vehicle is stopped, the BMU 12 controls the latent heat storage member 4 in the supercooled state to release the supercooled state by applying arbitrary energy according to the battery temperature, the outside air temperature, and whether or not the vehicle is started. .. This arbitrary energy includes, for example, "impact". That is, the BMU 12 transmits a control signal 16 to the driver 11 and drives the electromagnetic relay 13 by the driver 11 to give an impact to the latent heat storage member 4.

The electromagnetic relay 13 typically opens and closes a switch by physically moving a movable iron piece by an electromagnet. The electromagnetic relay 13 in the present embodiment directly or indirectly gives an impact to the latent heat storage member 4 to release the supercooled state. That is, the electromagnetic relay 13 generates vibration by operating the movable iron piece by, for example, an electromagnet, and gives an impact to release the supercooled state to the latent heat storage member 4. As shown in FIG. 2, the electromagnetic relay 13 is embedded in the latent heat storage member 4 and fixed on the inner bottom surface 2b. The electromagnetic relay 13 includes, for example, an electromagnet (not shown), a movable iron piece, a fixed iron piece, a return spring, and the like. When the electromagnet is energized, an attractive force is generated in the iron core and the movable iron piece collides with one of the fixed iron pieces. .. When the electromagnet is no longer energized, the force of the return spring causes the movable iron piece to return to its original state and collide with the other fixed iron piece. The electromagnetic relay 13 vibrates by repeating these operations.

Next, the thermal characteristics of the battery pack 1A according to the present embodiment will be described with reference to FIG. The DSC (Differential scanning calorimetry) curve shown in FIG. 3 shows the heat flow [mW] on the vertical axis and the temperature [° C.] on the horizontal axis. Details of DSC (Differential Scanning Calorimetry) will be omitted.

While the vehicle is running, heat is generated in each battery 3 and the battery temperature rises. The heat generated in each battery 3 is transferred to the latent heat storage member 4 via the outer peripheral surface 3a of each battery 3, and is temporarily stored in the latent heat storage member 4. The heat stored in the latent heat storage member 4 is partially transferred to the inner bottom surface 2b and the inner side surface 2c of the housing 2 in contact with the latent heat storage member 4, and is radiated from the outer surface of the housing 2 to the outside air or the like. Each battery 3 is cooled via the latent heat storage member 4. Further, when the battery temperature rises, the latent heat storage member 4 whose phase has changed to the liquid phase flows due to natural convection, shaking during vehicle running, etc., and the liquid temperature becomes uniform rapidly, and the inner bottom surface of the housing 2 is formed. Since heat is repeatedly transferred to 2b and the inner side surface 2c to promote heat dissipation from the outer surface of the housing 2 to the outside air and the like, the battery 3 can be continuously used at an allowable upper limit temperature of 60 ° C. or less, and the battery 3 can be used continuously. The progress of deterioration can be suppressed.

When a high load is applied to the battery 3 due to sudden acceleration or the like while the vehicle is running and the battery temperature rises sharply, the latent heat storage member 4 undergoes a phase change (melting) from a solid phase to a liquid phase at the melting point and becomes the battery 3. Since the generated heat is absorbed, it is possible to suppress an increase in the battery temperature. The latent heat storage member 4 in the present embodiment has a melting point that changes from a solid phase to a liquid phase at a temperature lower than the temperature corresponding to the upper limit temperature of the operating temperature range of the battery 3. When the battery 3 is a lithium-ion battery, if the battery temperature is in the operating temperature range (for example, -30 ° C to 60 ° C), it is possible to suppress the influence on the battery output and the battery life, but the environment where the upper limit temperature exceeds 60 ° C. Deterioration progresses when used in. The melting point (phase change temperature) of the latent heat storage member 4 is preferably set to a temperature lower than the upper limit temperature of 60 ° C., for example, in the range of 38 ° C. to 50 ° C. Further, the melting point of the latent heat storage member 4 is preferably 38 ° C. to 50 ° C., for example, when the upper limit temperature of the operating temperature range of the battery 3 is 60 ° C. Since the latent heat storage member 4 reaches the endothermic peak at a temperature higher than the melting point (arrow a in the figure), the melting point is before the upper limit temperature of the operating temperature range of the battery 3, so that the battery temperature is within the operating temperature range. It becomes possible to suppress it. The endothermic peak of the latent heat storage member 4 is preferably in the range of, for example, 45 ° C to 60 ° C. Further, the endothermic peak of the latent heat storage member 4 is preferably the upper limit temperature in the operating temperature range of the battery 3.

When a while has passed after the vehicle is stopped, the latent heat storage member 4 shifts to a supercooled state without phase change (solidification) from the liquid phase to the solid phase even if the temperature drops and reaches the freezing point. The latent heat storage member 4 in the present embodiment preferably has, for example, a freezing point substantially the same as the melting point and is in the range of 38 ° C to 50 ° C. When the latent heat storage member 4 shifts to the supercooled state, the latent heat storage member 4 maintains the supercooled state until the temperature at which the supercooled state is naturally released. In the present embodiment, the temperature at which the supercooled state is naturally released is referred to as a supercooled natural release point. The latent heat storage member 4 sets the supercooling natural release point near the lower limit temperature (for example, −30 ° C.) of the operating temperature range of the battery 3, so that the temperature range from the freezing point to the supercooling natural release point (hereinafter, “excessive”). In the "cooling region"), the supercooled state is maintained, and the supercooled state is released by the supercooling release unit 6 at an arbitrary timing.

The latent heat storage member 4 according to the present embodiment is released from the supercooled state according to the battery temperature and the outside air temperature. For example, when both the battery temperature and the outside air temperature are low at the start of the vehicle, the latent heat storage member 4 can be released from the overcooled state, so that the solidification heat generated in the latent heat storage member 4 can be transferred to the battery 3. , Secure or maintain the output characteristics of the battery 3. If the latent heat storage member 4 is kept in a supercooled state and is warmed by an increase in the battery temperature to reach the melting point, the heat absorption effect due to the phase change may not be obtained. The cooling state is released.

Next, the operation of the supercooling release unit 6 in the battery pack 1A will be described with reference to FIG. The supercooling release unit 6 is assumed to be activated, for example, when the vehicle is started (for example, the ignition is turned on), but the supercooling release unit 6 is not limited to this. For example, it may be automatically started by a timer or started by a remote controller.

In step S11, the BMU 12 determines whether or not the vehicle has stopped in response to the vehicle stop signal received from the MPU. When the BMU 12 receives the vehicle stop signal from the MPU, the BMU 12 determines that the vehicle has stopped and proceeds to step S12. On the other hand, if the vehicle stop signal is not received from the MPU, step S11 is repeated.

In step S12, the BMU 12 determines whether or not the current battery temperature TB is equal to or lower than the battery temperature TL corresponding to the freezing point of the latent heat storage member 4. The battery temperature TB is obtained by the BMU 12 receiving the temperature sensor signal 14. The battery temperature TL is acquired by the BMU 12 from the internal memory, and is the battery temperature when the latent heat storage member 4 reaches the freezing point from a high temperature. As a result of the determination in step S12, if the battery temperature TB is equal to or lower than the battery temperature TL, the process proceeds to step S13. On the other hand, if the battery temperature TB exceeds the battery temperature TL, the process proceeds to step S16.

In step S13, the BMU 12 determines whether or not the outside air temperature is equal to or less than the first threshold temperature TS1. The outside air temperature is obtained by the BMU 12 receiving the external signal 17. The first threshold temperature TS1 is a preset temperature for determining whether or not to heat the battery 3, and is, for example, 10 ° C. The first threshold temperature TS1 is changed according to the type of the battery 3 (positive electrode, negative electrode, etc.). As a result of the determination in step S13, if the outside air temperature is equal to or lower than the first threshold temperature TS1, the process proceeds to step S14. On the other hand, if the outside air temperature exceeds the first threshold temperature TS1, the process proceeds to step S18.

In step S14, the BMU 12 determines whether or not the vehicle has started according to the vehicle start signal received from the MPU. When the BMU 12 receives the vehicle start signal from the MPU, it determines that the vehicle has started and proceeds to step S15. On the other hand, if the vehicle start signal has not been received from the MPU, the process returns to step S12.

In step S15, the BMU 12 releases the supercooled state of the latent heat storage member 4 and ends this process. Since the battery temperature TB of the BMU 12 is sufficiently lowered and it is necessary to transfer heat to the battery 3, the BMU 12 transmits a control signal 16 to the driver 11 and drives the electromagnetic relay 13 by the driver 11 to the latent heat storage member 4. Give a shock. The electromagnetic relay 13 generates vibration by operating a movable iron piece with an electromagnet to give an impact to the latent heat storage member 4.

In step S16, the BMU 12 determines whether or not the vehicle has started according to the vehicle start signal received from the MPU. When the vehicle start signal is received from the MPU, it is determined that the vehicle has started, and the process proceeds to step S17. On the other hand, when the vehicle start signal is not received from the MPS, it is determined that the vehicle has not started, and the process returns to step S12.

In step S17, the BMU 12 determines that the supercooled state of the latent heat storage member 4 cannot be released, and ends this process. Since the battery temperature TB has not sufficiently dropped and it is not necessary to transfer heat to the battery 3, the BMU 12 ends without releasing the supercooled state of the latent heat storage member 4.

In step S18, the BMU 12 determines whether or not the battery temperature TB is equal to or lower than the temperature obtained by adding the second threshold temperature TS2 to the outside air temperature. The second threshold temperature TS2 is an allowable temperature of the difference between the battery temperature TB and the outside air temperature. That is, it is preferable to release the supercooled state of the latent heat storage member 4 after the battery temperature TB drops to the same temperature as the outside air temperature, but the battery temperature TB drops to the same temperature as the outside air temperature after the vehicle is stopped. Takes a considerable amount of time. In FIG. 5, one of the vertical axes is the battery temperature [° C.], the other is the rate of temperature difference [%], and the horizontal axis is the time [seconds]. For example, as shown in FIG. 5, when the battery temperature TB immediately after the vehicle is stopped is 60 ° C., it takes about 1800 seconds (about 30 minutes) to drop to the same temperature as the outside air temperature of 25 ° C. Therefore, in the present embodiment, when the battery temperature TB drops to the same temperature as (outside air temperature + second threshold temperature TS2), the supercooled state of the latent heat storage member 4 is released. The second threshold temperature TS2 is, for example, a ratio of the temperature difference between the battery temperature TB (60 ° C. in the illustrated example) and the outside air temperature (25 ° C. in the illustrated example) when the vehicle is stopped is 5% (about 1.75 ° C.). When the ratio of the temperature difference between the battery temperature corresponding to the second threshold temperature TS2 and the outside air temperature is 5%, it takes about 800 seconds for the battery temperature TB to drop to the same temperature as (outside air temperature + second threshold temperature TS2). It will be shortened to (about 13 minutes). If the battery temperature TB exceeds the second threshold temperature TS2 as a result of the determination in step S18, the process returns to step S11. On the other hand, when the battery temperature TB is equal to or lower than the second threshold temperature TS2, the process proceeds to step S15.

As described above, the battery pack 1A according to the present embodiment includes a housing 2 having thermal conductivity and a plurality of batteries 3 arranged in the internal space 2a of the housing 2 and held in the housing 2. , The latent heat storage member 4 that is housed in the housing 2 and is directly connected to each battery 3 or via the heat conductive member 5 and shifts to the supercooled state below the freezing point, and the supercooled state of the latent heat storage member 4. The supercooling release unit 6 is provided. The latent heat storage member 4 has a melting point that changes from a solid phase to a liquid phase at a temperature lower than the temperature corresponding to the upper limit temperature of the operating temperature range of the battery 3, shifts to a supercooled state below the freezing point, and is supercooled. Maintain the supercooled state until the temperature at which the state is naturally released.

According to the battery pack 1A having the above configuration, for example, by releasing the supercooled state of the latent heat storage member 4 by the supercooling release unit 6 when the temperature of the vehicle is low, it is possible to suppress a decrease in the battery output at a low temperature. Further, since the latent heat of the latent heat storage member 4 is transferred to the battery 3 to suppress the decrease in the battery temperature, the decrease in the energy density due to the arrangement of the heaters in the battery pack 1A and the decrease in the fuel efficiency due to the increase in the power consumption are suppressed. It becomes possible.

Further, in the battery pack 1A having the above configuration, when the supercooling release unit 6 detects the start of the vehicle, the latent heat storage member 4 is impacted to release the supercooling state. As a result, by releasing the latent heat storage member 4 from the supercooled state when the vehicle is started, the solidification heat generated in the latent heat storage member 4 can be transferred to the battery 3, and the decrease in the battery output at the time of starting is suppressed. can do.

Further, in the battery pack 1A having the above configuration, when the supercooling release unit 6 starts after the vehicle is stopped, the battery temperature is equal to or lower than the temperature corresponding to the freezing point of the latent heat storage member 4, and the outside temperature is applied to the battery. The supercooled state is released when the temperature is equal to or less than the first threshold temperature TS1 that requires temperature. Thereby, for example, the supercooled state of the latent heat storage member 4 can be released according to the outside air temperature.

Further, in the battery pack 1A having the above configuration, after the vehicle is stopped, the battery temperature of the battery pack 1A is equal to or lower than the battery temperature corresponding to the freezing point of the latent heat storage member 4, and the outside air temperature is the first threshold temperature TS1. The overcooled state is released when the temperature exceeds the above temperature and is equal to or lower than the temperature obtained by adding the second threshold temperature TS2 to the outside air temperature. Thereby, for example, when the supercooled state of the latent heat storage member 4 is released according to the outside air temperature, it is possible to determine the release of the supercooled state without taking time.

Further, in the battery pack 1A having the above configuration, when the supercooling release unit 6 is started after the vehicle is stopped and the battery temperature is higher than the temperature corresponding to the freezing point of the latent heat storage member 4, the latent heat storage member 4 has a temperature higher than the temperature corresponding to the freezing point of the latent heat storage member 4. Since the supercooled state is not released, it is possible to release the supercooling at an appropriate timing.

Further, the battery pack 1A having the above configuration includes an electromagnetic relay 13 in which the supercooling release unit 6 generates an impact based on the electric power of a different power source 7 in the battery pack 1A mounted on the vehicle. This makes it possible to drive the supercooling release unit 6 with, for example, a low voltage power supply 7 without stepping down the voltage of the battery pack 1A, which is a high voltage power supply.

Further, in the battery pack 1A having the above configuration, since the electromagnetic relay 13 is embedded in the latent heat storage member 4 and fixed on the inner bottom surface 2b, the latent heat storage member 4 can be directly impacted.

[Modification example]
In the above embodiment, the latent heat storage member 4 is directly thermally connected to each battery 3, but the present invention is not limited to this. FIG. 6 is a partial plan view showing a schematic configuration of the battery pack 1B according to the modified example of the embodiment. FIG. 7 is a cross-sectional view taken along the line BB in FIG. As shown in FIGS. 6 and 7, in the battery pack 1B, the latent heat storage member 4 is housed in the housing 2, and is connected to each battery 3 via the heat conductive member 5. The heat conductive member 5 is made of a heat conductive material having higher heat conductivity than the latent heat storage member 4. Examples of the heat conductive material include graphite, a resin containing a heat conductive filler, copper and aluminum which are metal materials having high heat conductivity. The heat conductive member 5 is made of, for example, sheet-shaped graphite. The heat conductive member 5 is thermally connected to at least each battery 3 and the latent heat storage member 4. The heat conductive member 5 is arranged along the arrangement direction of the plurality of batteries 3 and comes into contact with each outer peripheral surface 3a of the plurality of batteries 3. As shown in FIG. 6, the heat conductive member 5 is formed in a wavy shape along the outer peripheral surface 3a of each battery 3 arranged in the width direction when viewed from the vertical direction, and the batteries 3 are adjacent to each other in the depth direction. In the case, it is formed by being sandwiched between adjacent batteries 3. As shown in FIG. 7, the heat conductive member 5 has a contact portion 5a in contact with the outer peripheral surface 3a of the battery 3 and an extension portion 5b extending in the vertical direction from the contact portion 5a. The extension portion 5b is immersed in the latent heat storage member 4. The latent heat storage member 4 is filled on the inner bottom surface 2b of the housing 2 so that the extending portion 5b of the heat conductive member 5 is partially immersed (or buried).

Further, in the above embodiment, the case where the battery 3 is a cylindrical lithium ion battery has been described, but the battery 3 is not limited thereto. For example, it may be a prismatic battery or a battery other than a lithium ion battery.

Further, in the above embodiment, the electromagnetic relay 13 is embedded in the latent heat storage member 4 and fixed on the inner bottom surface 2b, but the present invention is not limited to this. For example, as shown in FIGS. 1, 2, 6, and 7, they may be arranged so as to be in contact with the outer side surface 2d of the housing 2, or may be arranged in the internal space 2a of the housing 2. May be good.

Further, in the above embodiment, the supercooling release unit 6 gives an impact to the latent heat storage member 4 by the electromagnetic relay 13, but the supercooling release unit 6 is limited to this as long as it can give an impact to the latent heat storage member 4. It is not something that is done. For example, a device using a piezo element that expands and contracts by applying a voltage may give an impact to the latent heat storage member 4 with the mover, or the fan may be impacted by the device that rotates the fan by applying a voltage. The latent heat storage member 4 may be agitated to give an impact. Further, the ultrasonic vibration generator may be arranged so as to be in contact with the outer side surface 2d of the housing 2, and the latent heat storage member 4 may be subjected to ultrasonic vibration by the ultrasonic wave generator. Further, a device that applies a high voltage to generate a spark discharge may give an impact to the latent heat storage member 4 with the spark discharge.

Further, in the above embodiment, the heat conductive member 5 has a configuration in which the extending portion 5b is partially immersed in the latent heat storage member 4, but the present invention is not limited to this. For example, the extension portion 5b may be partially immersed in the latent heat storage member 4, and the vertical end portion of the extension portion 5b may be in contact with the inner bottom surface 2b of the housing 2.

Further, in the above embodiment, the BMU 12 drives the electromagnetic relay 13 by the driver 11, but the BMU 12 may directly drive the electromagnetic relay 13 without going through the driver 11.

Further, in the above embodiment, the case where the battery packs 1A and 1B are applied to the power source mounted on the vehicle has been described, but the present invention is not limited to this, and the power source may be used for electronic devices and the like. ..

1A, 1B Battery pack 2 Housing 2a Internal space 2b Internal bottom surface 2c Internal side surface 2d External side surface 3 Battery 3a Outer surface surface 4 Latent heat storage member 5 Heat conduction member 5a Contact part 6 Supercooling release part 7 Power supply 11 Driver 12 BMU
13 Electromagnetic relay 14 Temperature sensor signal 15 Voltage 16 Control signal 17 External signal TS1 First threshold temperature TS2 Second threshold temperature

Claims (2)

A housing with thermal conductivity and
A plurality of batteries arranged in the internal space of the housing and held in the housing,
A latent heat storage member that is housed in the housing and that directly contacts at least a part of each battery and shifts to a supercooled state below the freezing point.
A supercooling release means for releasing the supercooled state of the latent heat storage member,
Equipped with
The latent heat storage member is
It has a melting point that changes phase from solid phase to liquid phase at a temperature lower than the temperature corresponding to the upper limit temperature of the operating temperature range of the battery.
The supercooled state is maintained below the freezing point until the temperature shifts to the supercooled state and the supercooled state is naturally released.
The latent heat storage member is stored in the inner bottom surface of the housing that faces the plurality of batteries in the vertical direction.
The latent heat storage member is housed in the liquid phase, leaving the internal space of the housing, and is stored so as to cover at least a part of each battery .
The supercooling release means is
A start detection means for detecting the start of a vehicle driven by the battery pack is provided.
When the start of the vehicle is detected by the start detection means, arbitrary energy is applied to the latent heat storage member to release the supercooled state.
When the temperature of the battery is equal to or lower than the temperature corresponding to the freezing point of the latent heat storage member and the outside air temperature is equal to or lower than the first threshold temperature at which the battery needs to be heated at the time of starting after the vehicle has stopped. , Release the supercooled state,
A battery pack that features that. The supercooling release means is
After the vehicle has stopped, the temperature of the battery is equal to or lower than the battery temperature corresponding to the freezing point of the latent heat storage member, the outside air temperature exceeds the first threshold temperature, and the temperature of the battery is the outside air temperature. When the temperature is equal to or lower than the temperature obtained by adding the second threshold temperature to the above, the overcooled state is released.
The battery pack according to claim 1.

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